2024-03-28T22:16:24Zhttp://uvadoc.uva.es/oai/requestoai:uvadoc.uva.es:10324/151552021-06-23T13:27:17Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Libstable: Fast, Parallel and High-Precision Computation of -Stable Distributions in C/C++ and MATLAB
Royuela del Val, Javier
Simmross Wattenberg, Federico Jesús
Alberola López, Carlos
Alpha-stable distributions
Numerical calculation
Parallel processing
-stable distributions are a wide family of probability distributions used in many
elds where probabilistic approaches are taken. However, the lack of closed analytical
expressions is a major drawback for their application. Currently, several tools have been
developed to numerically evaluate their density and distribution functions or estimate
their parameters, but available solutions either do not reach su cient precision on their
evaluations or are too slow for several practical purposes. Moreover, they do not take full
advantage of the parallel processing capabilities of current multi-core machines. Other solutions
work only on a subset of the -stable parameter space. In this paper we present a
C/C++ library and a MATLAB front-end that allows fully parallelized, fast and high precision
evaluation of density, distribution and quantile functions (PDF, CDF and CDF1
respectively), random variable generation and parameter estimation of -stable distributions
in their whole parameter space. The library provided can be easily integrated on
third party developments.
2015-12-21T11:19:58Z
2015-12-21T11:19:58Z
2015
info:eu-repo/semantics/article
Journal of Statistical Software
http://uvadoc.uva.es/handle/10324/15155
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
oai:uvadoc.uva.es:10324/151542021-06-28T11:17:19Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Non-Rigid Groupwise Registration for Motion Estimation and Compensation in Compressed Sensing Reconstruc- tion of Breath-Hold Cardiac Cine MRI
Royuela del Val, Javier
Cordero Grande, Lucilio
Simmross Wattenberg, Federico Jesús
Martín Fernández, Marcos Antonio
Alberola López, Carlos
dynamic MRI reconstruction, compressive sensing, groupwise registration
Purpose: Compressed sensing methods with motion estimation and compensation techniques
have been proposed for the reconstruction of accelerated dynamic MRI. However, artifacts that
naturally arise in compressed sensing reconstruction procedures hinder the estimation of motion
from reconstructed images, especially at high acceleration factors. This work introduces a robust
groupwise non-rigid motion estimation technique applied to the compressed sensing reconstruction
of dynamic cardiac cine MRI sequences.
Theory and Methods: A spatio-temporal regularized, groupwise, non-rigid registration method
based on a B-splines deformation model and a least squares metric is used to estimate and to
compensate the movement of the heart in breath-hold cine acquisitions and to obtain a quasi-static
sequence with highly sparse representation in temporally transformed domains.
Results: Short axis in vivo datasets are used for validation, both original multi-coil as well as
DICOM data. Fully sampled data were retrospectively undersampled with various acceleration
factors and reconstructions were compared with the two well-known methods k-t FOCUSS and
MASTeR. The proposed method achieves higher signal to error ratio and structure similarity index
for medium to high acceleration factors.
Conclusions: Reconstruction methods based on groupwise registration show higher quality recon-
structions for cardiac cine images than the pairwise counterparts tested.
2015-12-21T11:11:52Z
2015-12-21T11:11:52Z
2015
info:eu-repo/semantics/article
Magnetic Resonance in Medicine (aceptado para su publicación)
http://uvadoc.uva.es/handle/10324/15154
spa
http://onlinelibrary.wiley.com/doi/10.1002/mrm.25733/pdf
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
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oai:uvadoc.uva.es:10324/151562021-06-23T13:27:18Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Multi-Oriented Windowed Harmonic Phase Reconstruction for Robust Cardiac Strain Imaging
Cordero Grande, Lucilio
Royuela del Val, Javier
Sanz Estébanez, Santiago Rodrigo
Martín Fernández, Marcos Antonio
Alberola López, Carlos
Tagged Magnetic Resonance Imaging
Harmonic Phase Reconstruction
Artifacts
Strain Tensor
Windowed Fourier Transform
The purpose of this work is to develop a method for direct estimation of
the cardiac strain tensor by extending the harmonic phase reconstruction on
tagged magnetic resonance images to obtain more precise and robust measurements.
The extension relies on the reconstruction of the local phase of
the image by means of the windowed Fourier transform and the acquisition of
an overdetermined set of stripe orientations in order to avoid the phase interferences
from structures outside the myocardium and the instabilities arising
from the application of a gradient operator. Results have shown that increasing
the number of acquired orientations provides a signi cant improvement
in the reproducibility of the strain measurements and that the acquisition of
an extended set of orientations also improves the reproducibility when compared
with acquiring repeated samples from a smaller set of orientations.
Additionally, biases in local phase estimation when using the original harmonic
phase formulation are greatly diminished by the one here proposed.
The ideas here presented allow the design of new methods for motion sensitive
magnetic resonance imaging, which could simultaneously improve the
resolution, robustness and accuracy of motion estimates.
2015-12-21T11:25:58Z
2015-12-21T11:25:58Z
2015
info:eu-repo/semantics/article
https://doi.org/doi:10.1016/j.media.2015.12.001
Medical Image Analysis (en prensa)
http://uvadoc.uva.es/handle/10324/15156
spa
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
oai:uvadoc.uva.es:10324/151572021-06-23T13:27:20Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Multi-Stencil Streamline Fast Marching: a general 3D Framework to determine Myocardial Thickness and Transmurality in Late Enhancement Images
Merino Caviedes, Susana
Cordero Grande, Lucilio
Revilla Orodea, Ana
Sevilla Ruiz, María Teresa
Pérez García, María Teresa
Martín Fernández, Marcos Antonio
Alberola López, Carlos
Perfusion imaging
heart
quantification and estimation
myocardial viability
transmurality
fast marching
We propose a fully three-dimensional methodology
for the computation of myocardial non-viable tissue transmurality
in contrast enhanced magnetic resonance images. The outcome
is a continuous map defined within the myocardium where not
only current state-of-the-art measures of transmurality can be
calculated, but also information on the location of non-viable
tissue is preserved. The computation is done by means of a
partial differential equation framework we have called Multi-
Stencil Streamline Fast Marching (MSSFM). Using it, the myocardial
and scarred tissue thickness is simultaneously computed.
Experimental results show that the proposed 3D method allows
for the computation of transmurality in myocardial regions where
current 2D methods are not able to as conceived, and it also
provides more robust and accurate results in situations where the
assumptions on which current 2D methods are based —i.e., there
is a visible endocardial contour and its corresponding epicardial
points lie on the same slice—, are not met.
2015-12-21T11:35:50Z
2015-12-21T11:35:50Z
2014
info:eu-repo/semantics/article
https://doi.org/10.1109/TMI.2013.2276765
IEEE Transactions on Medical Imaging, Vol. 33, No. 1, pp. 23-37, Enero 2014.
http://uvadoc.uva.es/handle/10324/15157
spa
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
oai:uvadoc.uva.es:10324/151672021-06-23T13:27:22Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Anisotropic Diffusion Filter with Memory based on Speckle Statistics for Ultrasound Images
Ramos Llordén, Gabriel
Vegas Sánchez-Ferrero, Gonzalo
Martín Fernández, Marcos Antonio
Alberola López, Carlos
Aja Fernández, Santiago
Ultrasound Imaging
Speckle Filter
Anisotropic Diffusion
Memory Equations
Volterra Equations
Ultrasound imaging exhibits considerable difficulties for medical visual inspection and for the development of automatic
analysis methods due to speckle, which negatively affects the perception of tissue boundaries and the performance of automatic
segmentation methods. With the aim of alleviating the effect of speckle, many filtering techniques are usually considered as a
preprocessing step prior to automatic analysis methods or visual inspection. Most of the state-of-the-art filters try to reduce the
speckle effect without considering its relevance for the characterization of tissue nature. However, the speckle phenomenon is the
inherent response of echo signals in tissues and can provide important features for clinical purposes. This loss of information
is even magnified due to the iterative process of some speckle filters, e.g., diffusion filters, which tend to produce over-filtering
because of the progressive loss of relevant information for diagnostic purposes during the diffusion process. In this work, we
propose an anisotropic diffusion filter with a probabilistic-driven memory mechanism to overcome the over-filtering problem by
following a tissue selective philosophy. Specifically, we formulate the memory mechanism as a delay differential equation for
the diffusion tensor whose behavior depends on the statistics of the tissues, by accelerating the diffusion process in meaningless
regions and including the memory effect in regions where relevant details should be preserved. Results both in synthetic and real
US images support the inclusion of the probabilistic memory mechanism for maintaining clinical relevant structures, which are
removed by the state-of-the-art filters.
2015-12-21T13:01:21Z
2015-12-21T13:01:21Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1109/TIP.2014.2371244
IEEE Trans. on Image Processing, Vol. 24, No. 1, Enero 2015
http://uvadoc.uva.es/handle/10324/15167
spa
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
oai:uvadoc.uva.es:10324/213722021-06-23T13:27:38Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Coming down to Earth: Helping teachers use 3D virtual worlds in across-spaces learning situations
Muñoz Cristóbal, Juan Alberto
Prieto, Luis P.
Asensio Pérez, Juan Ignacio
Martínez Monés, Alejandra
Jorrín Abellán, Iván Manuel
Dimitriadis Damoulis, Ioannis
Realidad virtual
Google Earth
Producción Científica
Different approaches have explored how to provide seamless learning across multiple ICT-enabled physical and virtual spaces, including three-dimensional virtual worlds (3DVW). However, these approaches present limitations that may reduce their acceptance in authentic educational practice: The difficulties of authoring and sharing teacher-created designs across different 3DVW platforms, or the lack of integration of 3DVWs with existing technologies in the classroom ecosystem (e.g., widespread web-based learning platforms such as Moodle, or mobile augmented reality applications). Focusing on a specific kind of 3DVW (virtual globes, such as Google Earth, used like 3DVWs), we propose a system that enables teachers to deploy across-spaces learning situations, which can be authored with a plethora of existing learning design tools, that involve different common web-based learning platforms, mobile AR applications and multiple kinds of virtual globes. A prototype of the architecture has been developed to evaluate this novel approach. The mixed-methods evaluation performed comprised both a feature analysis and a study where a teacher deployed an authentic across-spaces learning situation including Google Earth used as a 3DVW. Such evaluation shows that the system enables teachers deploy learning situations over different technological ecosystems composed by physical and web spaces, as well as by 3DVWs.
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14)
2016-11-30T13:44:01Z
2016-11-30T13:44:01Z
2015
info:eu-repo/semantics/article
Muñoz-Cristóbal, J. A., Prieto, L. P., Asensio-Pérez, J. I., Martínez-Monés, A., Jorrín-Abellán, I. M., & Dimitriadis, Y. (2015). Coming down to Earth: Helping teachers use 3D virtual worlds in across-spaces learning situations. Journal of Educational Technology & Society, 18(1), p. 13-26
1436-4522
http://uvadoc.uva.es/handle/10324/21372
13
1
26
Journal of Educational Technology & Society
18
spa
http://www.ifets.info/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
International Forum of Educational Technology and Society
oai:uvadoc.uva.es:10324/215122021-06-23T13:27:49Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Aprendizaje ubicuo: un proceso formativo en educación física en el medio natural
Ubiquitous learning: a learning process in Physical Education in the Natural Environment
Gallego Lema, Vanesa
Muñoz Cristóbal, Juan Alberto
Arribas Cubero, Higinio Francisco
Rubia Avi, Bartolomé
Tecnología educativa
Docentes-Formación
Educación física
Producción Científica
Este artículo presenta un proceso formativo de aprendizaje ubicuo con apoyo tecnológico, desarrollado en el área de Educación Física en el Medio Natural (EFMN). La investigación ha permitido analizar cómo repercute el aprendizaje ubicuo en la enseñanza/aprendizaje en el Grado de Educación Primaria en Educación Física, apoyándose en estudios de caso. Entre otros resultados, el aprendizaje ubicuo ha favorecido que el alumnado y el profesor hayan interactuado en el proceso desde distintos espacios y momentos, uniendo los ámbitos formales e informales, así como aportando un beneficio en los distintos elementos del currículum oficial. De esta manera, el alumnado ha incrementado su competencia digital, junto con una mejor adquisición de los contenidos de la asignatura, superando las distintas problemáticas que han emergido durante el proceso. Las conclusiones señalan que las herramientas tecnológicas han apoyado el currículum de EFMN, favoreciendo un proceso formativo ubicuo. Describimos la experiencia formativa realizada en la asignatura durante el curso 2012-2013, junto con su implementación tecnológica.
In this paper we present a technologysupported ubiquitous learning process, developed in the area of Physical Education in the Natural Environment. The research conducted allowed us to analyze how ubiquitous learning impacted on the teaching / learning process in a university degree on Primary Education with a major in Physical Education, using a case study method.
Among other findings, the research results suggest that ubiquitous learning encouraged students and teacher to interact in the learning process from different places and times, linking formal and informal settings, as well as providing a benefit in different elements of the official curriculum. In this way, students increased its digital competence and they achieved a better understanding of the contents of the subject, overcoming problems that emerged during the process. The conclusions we reached point out that technological tools supported the EFMN curriculum, causing an ubiquitous training process. In this paper, we describe the educational experience carried out in the subject during the 20122013 academic year, as well as the technological implementation performed.
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14)
Ministerio de Economía, Industria y Competitividad (TIN201453199C32R)
2016-12-09T19:38:02Z
2016-12-09T19:38:02Z
2016
info:eu-repo/semantics/article
https://doi.org/10.17398/1695288X. 15.1.59
RELATEC: Revista Latinoamericana de Tecnología Educativa, 2016, vol. 15, nº 1, p. 59-73
1695-288X
http://uvadoc.uva.es/handle/10324/21512
59
1
73
RELATEC: Revista Latinoamericana de Tecnología Educativa
15
spa
http://relatec.unex.es
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Universidad de Extremadura
oai:uvadoc.uva.es:10324/215292021-09-10T09:32:09Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Assessment of Time and Frequency Domain Entropies to Detect Sleep Apnoea in Heart Rate Variability Recordings from Men and Women
Gutiérrez Tobal, Gonzalo César
Álvarez González, Daniel
Gómez Pilar, Javier
Campo Matias, Félix del
Hornero Sánchez, Roberto
sleep apnoea
Producción Científica
Heart rate variability (HRV) provides useful information about heart dynamics
both under healthy and pathological conditions. Entropy measures have shown their utility
to characterize these dynamics. In this paper, we assess the ability of spectral entropy (SE)
and multiscale entropy (MsE) to characterize the sleep apnoea-hypopnea syndrome (SAHS)
in HRV recordings from 188 subjects. Additionally, we evaluate eventual differences in
these analyses depending on the gender. We found that the SE computed from the very low
frequency band and the low frequency band showed ability to characterize SAHS regardless
the gender; and that MsE features may be able to distinguish gender specificities. SE and
MsE showed complementarity to detect SAHS, since several features from both analyses
were automatically selected by the forward-selection backward-elimination algorithm.
Finally, SAHS was modelled through logistic regression (LR) by using optimum sets of
selected features. Modelling SAHS by genders reached significant higher performance than
doing it in a jointly way. The highest diagnostic ability was reached by modelling SAHS in
women. The LR classifier achieved 85.2% accuracy (Acc) and 0.951 area under the ROC
curve (AROC). LR for men reached 77.6% Acc and 0.895 AROC, whereas LR for the whole set reached 72.3% Acc and 0.885 AROC. Our results show the usefulness of the SE and MsE
analyses of HRV to detect SAHS, as well as suggest that, when using HRV, SAHS may be
more accurately modelled if data are separated by gender.
Ministerio de Economía, Industria y Competitividad (TEC2011-22987)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA059U13)
2016-12-12T12:35:40Z
2016-12-12T12:35:40Z
2015
info:eu-repo/semantics/article
https://doi.org/10.3390/e17010123
Entropy 2015, 17, p. 123-141
ISSN 1099-4300
http://uvadoc.uva.es/handle/10324/21529
17
Entropy
eng
www.mdpi.com/journal/entropy
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
MDPI
oai:uvadoc.uva.es:10324/215552021-06-23T13:27:51Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Neural Network Reorganization Analysis During an Auditory Oddball Task in Schizophrenia Using Wavelet Entropy
Gómez Pilar, Javier
Poza Crespo, Jesús
Bachiller Matarranz, Alejandro
Gómez Peña, Carlos
Molina Rodríguez, Vicente
Hornero Sánchez, Roberto
wavelet entropy
Producción Científica
The aim of the present study was to characterize the neural network
reorganization during a cognitive task in schizophrenia (SCH) by means of wavelet
entropy (WE). Previous studies suggest that the cognitive impairment in patients with SCH
could be related to the disrupted integrative functions of neural circuits. Nevertheless,
further characterization of this effect is needed, especially in the time-frequency domain.
This characterization is sensitive to fast neuronal dynamics and their synchronization that
may be an important component of distributed neuronal interactions; especially in light of
the disconnection hypothesis for SCH and its electrophysiological correlates. In this work,
the irregularity dynamics elicited by an auditory oddball paradigm were analyzed through
synchronized-averaging (SA) and single-trial (ST) analyses. They provide complementary
information on the spatial patterns involved in the neural network reorganization. Our
results from 20 healthy controls and 20 SCH patients showed a WE decrease from baseline
to response both in controls and SCH subjects. These changes were significantly more pronounced for healthy controls after ST analysis, mainly in central and frontopolar areas.
On the other hand, SA analysis showed more widespread spatial differences than ST
results. These findings suggest that the activation response is weakly phase-locked to
stimulus onset in SCH and related to the default mode and salience networks. Furthermore,
the less pronounced changes in WE from baseline to response for SCH patients suggest an
impaired ability to reorganize neural dynamics during an oddball task.
Ministerio de Economía, Industria y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA059U13)
Fondo de Investigaciones Sanitarias del Instituto de Salud Carlos III” (FIS PI1102303)
Gerencia Regional de Salud de Castilla y León” (GRS 613/A/11; GRS 932/A/14)
2016-12-13T07:40:34Z
2016-12-13T07:40:34Z
2015
info:eu-repo/semantics/article
https://doi.org/10.3390/e17085241
Entropy 2015, 17, p. 5241-5256
1099-4300
http://uvadoc.uva.es/handle/10324/21555
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
MDPI
oai:uvadoc.uva.es:10324/215592021-06-23T13:27:29Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
MEG Analysis of Neural Interactions in Attention-Deficit/Hyperactivity Disorder
Khadmaoui, Amine
Gómez Peña, Carlos
Poza Crespo, Jesús
Bachiller Matarranz, Alejandro
Fernández, Alberto
Quintero, Javier
Hornero Sánchez, Roberto
Neural Interactions
Producción Científica
The aim of the present study was to explore the interchannel relationships of resting-state brain activity in patients with attentiondeficit/hyperactivity disorder (ADHD), one of the most common mental disorders that develop in children. Magnetoencephalographic (MEG) signals were recorded using a 148-channel whole-head magnetometer in 13 patients with ADHD (range: 8–12 years) and 14 control subjects (range: 8–13 years).Three complementary measures (coherence, phase-locking value, and Euclidean distance) were calculated in the conventionalMEG frequency bands: delta, theta, alpha, beta, and gamma. Our results showed that the interactions among MEG channels are higher for ADHD patients than for control subjects in all frequency bands. Statistically significant differences were observed for short-distance values within right-anterior and central regions, especially at delta, beta,
and gamma-frequency bands (𝑝 < 0.05; Mann-Whitney 𝑈 test with false discovery rate correction). These frequency bands also showed statistically significant differences in long-distance interactions, mainly among anterior and central regions, as well as among anterior, central, and other areas. These differences might reflect alterations during brain development in children with ADHD. Our results support the role of frontal abnormalities in ADHD pathophysiology, which may reflect a delay in cortical maturation in the frontal cortex.
Ministerio de Economía, Industria y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA059U13
2016-12-13T08:14:38Z
2016-12-13T08:14:38Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1155/2016/8450241
Computational Intelligence and Neuroscience, Volume 2016, Article ID 8450241, 10 pages
1687-5265
http://uvadoc.uva.es/handle/10324/21559
eng
https://www.hindawi.com/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Hindawi Publishing Corporation
oai:uvadoc.uva.es:10324/215902021-09-10T09:32:39Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Diagnosis of pediatric obstructive sleep apnea: Preliminary findingsusing automatic analysis of airflow and oximetry recordings obtainedat patients’ home
Gutiérrez Tobal, Gonzalo César
Alonso Álvarez, María Luz
Álvarez González, Daniel
Campo Matias, Félix del
Terán Santos, Joaquín
Hornero Sánchez, Roberto
Pediatric obstructive sleep apnea
Producción Científica
The obstructive sleep apnea syndrome (OSAS) greatly affects both the health and the quality of life of chil-dren. Therefore, an early diagnosis is crucial to avoid their severe consequences. However, the standarddiagnostic test (polysomnography, PSG) is time-demanding, complex, and costly. We aim at assessinga new methodology for the pediatric OSAS diagnosis to reduce these drawbacks. Airflow (AF) and oxy-gen saturation (SpO2) at-home recordings from 50 children were automatically processed. Informationfrom the spectrum of AF was evaluated, as well as combined with 3% oxygen desaturation index (ODI3)through a logistic regression model. A bootstrap methodology was conducted to validate the results.OSAS significantly increased the spectral content of AF at two abnormal frequency bands below (BW1)and above (BW2) the normal respiratory range. These novel bands are consistent with the occurrenceof apneic events and the posterior respiratory overexertion, respectively. The spectral information fromBW1 and BW2 showed complementarity both between them and with ODI3. A logistic regression modelbuilt with 3 AF spectral features (2 from BW1 and 1 from BW2) and ODI3 achieved (mean and 95% confi-dence interval): 85.9% sensitivity [64.5–98.7]; 87.4% specificity [70.2–98.6]; 86.3% accuracy [74.9–95.4];0.947 area under the receiver-operating characteristics curve [0.826–1]; 88.4% positive predictive value[72.3–98.5]; and 85.8% negative predictive value [65.8–98.5]. The combination of the spectral informationfrom two novel AF bands with the ODI3 from SpO2is useful for the diagnosis of OSAS in children.
Ministerio de Economía y Competitividad (project TEC2011-22987)
Junta de Castilla y León (project VA059U13)
2016-12-13T12:32:40Z
2016-12-13T12:32:40Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1016/j.bspc.2015.02.014
Biomedical Signal Processing and Control 18 (2015) 401–407
1746-8094
http://uvadoc.uva.es/handle/10324/21590
eng
http://www.sciencedirect.com
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/215912021-06-23T13:27:39Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
MEG analysis of neural dynamics in attention-deficit/hyperactivity disorder with fuzzy entropy
Monge, Jesús
Gómez Peña, Carlos
Poza Crespo, Jesús
Fernández, Alberto
Quintero, Javier
Hornero Sánchez, Roberto
Attention-deficit/hyperactivitydisorder
Producción Científica
The aim of this study was to analyze the neural dynamics in attention-deficit/hyperactivity disorder (ADHD). For this purpose, magnetoencephalographic (MEG) background activity was analyzed using fuzzy entropy (FuzzyEn), an entropy measure that quantifies signal irregularity, in 13 ADHD patients and 14 control children. Additionally, relative power (RP) was computed in conventional frequency bands (delta, theta, alpha, beta and gamma). FuzzyEn results showed that MEG activity was more regular in ADHD patients than in controls. Moreover, we found an increase of power in delta band and a decrease in the remaining frequency bands. Statistically significant differences (p-values <0.05; nonparametric permutation test for multiple comparisons) were detected for FuzzyEn in the posterior and left temporal regions, and for RP in the posterior, anterior and left temporal regions. Our results support the hypothesis that ADHD involves widespread functional brain abnormalities, affecting more areas than fronto-striatal circuits, such as the left temporal and posterior regions.
Ministerio de Economía y Competitividad (project TEC2011-22987)
Junta de Castilla y León (project BIO/VA38/14 and project VA059U13)
2016-12-13T12:39:07Z
2016-12-13T12:39:07Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1016/j.medengphy.2015.02.006
Medical Engineering and Physics 37 (2015) 416–423
1350-4533
http://uvadoc.uva.es/handle/10324/21591
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/215932021-06-23T13:27:24Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Auditory P3a and P3b neural generators in schizophrenia: An adaptive sLORETA P300 localization approach
Bachiller Matarranz, Alejandro
Romero, Sergio
Molina Rodríguez, Vicente
Alonso, Joan F.
Mañanas, Miguel A.
Poza Crespo, Jesús
Hornero Sánchez, Roberto
Schizophrenia
Producción Científica
The present study investigates the neural substrates underlying cognitive processing in schizophrenia (Sz) patients. To this end, an auditory 3-stimulus oddball paradigm was used to identify P3a and P3b components, elicited by rare-distractor and rare-target tones, respectively. Event-related potentials (ERP) were recorded from 31 Sz patients and 38 healthy controls. The P3a and P3b brain-source generators were identified by timeaveraging
of low-resolution brain electromagnetic tomography (LORETA) current density images. In contrast with the commonly used fixed window of interest (WOI), we proposed to apply an adaptive WOI, which takes into account subjects' P300 latency variability. Our results showed different P3a and P3b source activation patterns in both groups. P3b sources included frontal, parietal and limbic lobes,whereas P3a response generators were localized over bilateral frontal and superior temporal regions. These areas have been related to the discrimination of auditory stimulus and to the inhibition (P3a) or the initiation (P3b) of motor response in a
cognitive task. In addition, differences in source localization between Sz and control groups were observed. Sz patients showed lower P3b source activity in bilateral frontal structures and the cingulate. P3a generators were less widespread for Sz patients than for controls in right superior, medial and middle frontal gyrus. Our findings suggest that target and distractor processing involves distinct attentional subsystems, both being altered in Sz. Hence, the study of neuroelectric brain information can provide further insights to understand cognitive
processes and underlying mechanisms in Sz.
Ministerio de Economía y Competitividad (projects TEC2014-53196-R, DPI2011-22680 and DPI2014-59049-R),
Junta de Castilla y León (VA059U13)
Instituto de Salud Carlos III’, ISCIII (FIS PI1102303)
Gerencia Regional de Salud de Castilla y León (GRS 613/A/11; GRS 932/A/14)
2016-12-13T12:45:30Z
2016-12-13T12:45:30Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1016/j.schres.2015.09.028
Schizophrenia Research, 2015, vol. 169, p. 318–325
0920-9964
http://uvadoc.uva.es/handle/10324/21593
eng
http://www.sciencedirect.com/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/215942021-09-10T09:33:45Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Regularity analysis of nocturnal oximetry recordings to assist in the diagnosis of sleep apnoea syndrome
Marcos, J. Víctor
Hornero Sánchez, Roberto
Nabney, Ian T.
Álvarez González, Daniel
Gutiérrez Tobal, Gonzalo César
Campo Matias, Félix del
Oxygen saturation
Producción Científica
The relationship between sleep apnoea–hypopnoea syndrome (SAHS) severity and the regularity of noctur- nal oxygen saturation (SaO 2 ) recordings was analysed. Three different methods were proposed to quantify regularity: approximate entropy (AEn), sample entropy (SEn) and kernel entropy (KEn). A total of 240 sub- jects suspected of suffering from SAHS took part in the study. They were randomly divided into a training set (96 subjects) and a test set (144 subjects) for the adjustment and assessment of the proposed methods, respectively. According to the measurements provided by AEn, SEn and KEn, higher irregularity of oximetry signals is associated with SAHS-positive patients. Receiver operating characteristic (ROC) and Pearson corre- lation analyses showed that KEn was the most reliable predictor of SAHS. It provided an area under the ROC curve of 0.91 in two-class classification of subjects as SAHS-negative or SAHS-positive. Moreover, KEn mea- surements from oximetry data exhibited a linear dependence on the apnoea–hypopnoea index, as shown by a correlation coefficient of 0.87. Therefore, these measurements could be used for the development of simplified diagnostic techniques in order to reduce the demand for polysomnographies. Furthermore, KEn represents a convincing alternative to AEn and SEn for the diagnostic analysis of noisy biomedical signals.
Junta de Castilla y León (project VA059U13)
Ministerio de Economía y Competitividad (project TEC 2011–22987)
2016-12-13T12:52:04Z
2016-12-13T12:52:04Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1016/j.medengphy.2015.11.010
Medical Engineering and Physics 38 (2016) 216–224
1350-4533
http://uvadoc.uva.es/handle/10324/21594
eng
http://www.elsevier.com/locate/medengphy
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/216792021-09-10T09:34:12Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Utility of AdaBoost to Detect Sleep Apnea-Hypopnea Syndrome From Single-Channel Airflow
Gutiérrez Tobal, Gonzalo César
Álvarez González, Daniel
Campo Matias, Félix del
Hornero Sánchez, Roberto
AdaBoost
Producción Científica
The purpose of this study is to evaluate the usefulness of the boosting algorithm AdaBoost (AB) in the context of the sleep apnea-hypopnea syndrome (SAHS) diagnosis. Methods: We characterize SAHS in single-channel airflow (AF) signals from 317 subjects by the extraction of spectral and non-linear features. Relevancy and redundancy analyses are conducted through the fast correlation-based filter (FCBF) to derive the optimum set of features among them. These are used to feed classifiers based on linear discriminant analysis (LDA) and classification and regression trees (CART). LDA and CART models are sequentially obtained through AB, which combines their performances to reach higher diagnostic ability than each of them separately. Results: Our AB-LDA and AB-CART approaches showed high diagnostic performance when determining SAHS and its severity. The assessment of different apnea-hypopnea index cutoffs using an independent test set derived into high accuracy: 86.5% (5 events/h), 86.5% (10 events/h), 81.0% (15 events/h), and 83.3% (30 events/h). These results widely outperformed those from logistic regression and a conventional event-detection algorithm applied to the same database. Conclusion: Our results suggest that AB applied to data from single-channel AF can be useful to determine SAHS and its severity. Significance: SAHS detection might be simplified through the only use of single-channel AF data.
Ministerio de Economía y Competitividad (project TEC2011-22987)
Junta de Castilla y León (project VA059U13)
2016-12-14T06:45:22Z
2016-12-14T06:45:22Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1109/TBME.2015.2467188
IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING, VOL. 63, NO. 3, MARCH 2016
0018-9294
http://uvadoc.uva.es/handle/10324/21679
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Institute of Electrical and Electronics Engineers (IEEE)
oai:uvadoc.uva.es:10324/216802021-06-23T13:27:34Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Characterization of EEG patterns in brain-injured subjects and controls after a Snoezelen® intervention
Gómez Peña, Carlos
Poza Crespo, Jesús
Gutiérrez, María T.
Prada, Esther
Mendoza, Nuria
Hornero Sánchez, Roberto
Brain-injury
Producción Científica
Background and objective. The aim of this study was to assess the changes induced in electroencephalographic (EEG) activity by a Snoezelen® intervention on individuals with brain-injury and control subjects. Methods: EEG activity was recorded preceding and following a Snoezelen® session in 18 people with cerebral palsy (CP), 18 subjects who have sustained traumatic brain-injury (TBI) and 18 controls. EEG data were analyzed by means of spectral and nonlinear measures: median frequency (MF), individual alpha frequency (IAF), sample entropy (SampEn) and Lempel-Ziv complexity (LZC). Results: Our results showed decreased values for MF, IAF, SampEn and LZC as a consequence of the therapy. The main changes between pre-stimulation and post-stimulation conditions were found in occipital and parietal brain areas. Additionally, these changes are more widespread in controls than in brain-injured subjects, which can be due to cognitive deficits in TBI and CP groups. Conclusions: Our findings support the notion that Snoezelen® therapy affects central nervous system, inducing a slowing of oscillatory activity, as well as a decrease of EEG complexity and irregularity. These alterations seem to be related with higher levels of relaxation of the participants.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (VA059U13 y BIO/VA08/15)
2016-12-14T06:57:05Z
2016-12-14T06:57:05Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1016/j.cmpb.2016.08.008
Computer methods and programs in biomedicine 136 ( 2016 ) 1–9
0169-2607
http://uvadoc.uva.es/handle/10324/21680
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/216812021-06-23T13:27:40Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Effect of infusion tests on the dynamical properties of intracranial pressure in hydrocephalus
García Gadañón, María
Poza Crespo, Jesús
Bachiller Matarranz, Alejandro
Santamarta Gómez, David
Hornero Sánchez, Roberto
Hydrocephalus
Producción Científica
Hydrocephalus comprises a number of conditions
characterised by clinical symptoms, dilated ventricles and anomalous cerebrospinal fluid
(CSF) dynamics. Infusion tests (ITs) are usually performed to study CSF circulation and in
the preoperatory evaluation of patients with hydrocephalus. The study of intracranial pressure
(ICP) signals recorded during ITs could be useful to gain insight into the underlying
pathophysiology of this condition and to further support treatment decisions. In this study,
two wavelet parameters, wavelet turbulence (WT) and wavelet entropy (WE), were analysed
in order to characterise the variability, irregularity and similarity in spectral content of ICP
signals in hydrocephalus.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (project VA059U13)
2016-12-14T07:10:17Z
2016-12-14T07:10:17Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1016/j.cmpb.2016.06.007
computer methods and programs in biomedicine 134 ( 2016 ) 225–235
0169-2607
http://uvadoc.uva.es/handle/10324/21681
eng
http://www.sciencedirect.com
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/216822021-09-10T09:33:11Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Neurofeedback training with a motor imagery-based BCI: neurocognitive improvements and EEG changes in the elderly
Gómez Pilar, Javier
Corralejo Palacios, Rebeca
Nicolás Alonso, Luis Fernando
Álvarez González, Daniel
Hornero Sánchez, Roberto
Brain Computer Interface (BCI)
Producción Científica
Neurofeedback training (NFT) has shown to be promising and useful to rehabilitate cognitive functions. Recently, brain-computer interfaces (BCIs) were used to restore brain plasticity by inducing brain activity with a NFT. In our study, we hypothesized that a NFT with a motor imagery-based BCI (MI-BCI) could enhance cognitive functions related to aging effects. To assess the effectiveness of our MI-BCI application, 63 subjects (older than 60 years) were recruited. This novel application was used by 31 subjects (NFT group). Their Luria neuropsychological test scores were compared with the remaining 32 subjects, who did not perform NFT (control group). Electroencephalogram (EEG) changes measured by relative power (RP) endorsed cognitive potential findings under study: visuospatial, oral language, memory, intellectual and attention functions. Three frequency bands were selected to assess cognitive changes: 12, 18, and 21 Hz (bandwidth 3 Hz). Significant increases (p<0.01) in the RP of these frequency bands were found. Moreover, results from cognitive tests showed significant improvements (p<0.01) in four cognitive functions after performing five NFT sessions: visuospatial, oral language, memory, and intellectual. This established evidence in the association between NFT performed by a MI-BCI and enhanced cognitive performance. Therefore, it could be a novel approach to help elderly people.
Ministerio de Economía y Competitividad (TEC2014-53196)
Junta de Castilla y León (VA059U13)
2016-12-14T07:27:22Z
2016-12-14T07:27:22Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1007/s11517-016-1454-4
Medical and Biological Engineering and Computing (2016) 54:1655–1666
0140-0118
http://uvadoc.uva.es/handle/10324/21682
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Springer Verlag
oai:uvadoc.uva.es:10324/216832021-09-10T09:33:28Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Positive airway pressure and electrical stimulation methods for obstructive sleep apnea treatment: a patent review (2005-2014)
Álvarez González, Daniel
Gutiérrez Tobal, Gonzalo César
Campo Matias, Félix del
Hornero Sánchez, Roberto
Airflow limitation
Producción Científica
Introduction. Obstructive sleep apnea-hypopnea syndrome (OSAHS) is a major health problem with significant negative effects on the health and quality of life. Continuous positive airway pressure (CPAP) is currently the primary treatment option and it is considered the most effective therapy for OSAHS. Nevertheless, comfort issues due to improper fit to patient’s changing needs and breathing gas leakage limit the patient’s adherence to treatment.
Areas covered. The present patent review describes recent innovations in the treatment of OSAHS related to optimization of the positive pressure delivered to the patient, methods and systems for continuous self-adjusting pressure during inspiration and expiration phases, and techniques for electrical stimulation of nerves and muscles responsible for the airway patency.
Expert opinion. In the last years, CPAP-related inventions have mainly focused on obtaining an optimal self-adjusting pressure according to patient’s needs. Despite intensive research carried out, treatment compliance is still a major issue. Hypoglossal electrical nerve stimulation could be an effective secondary treatment option when CPAP primary therapy fails. Several patents have been granted focused on selective stimulation techniques and parameter optimization of the stimulating pulse waveform. Nevertheless, there remain important issues to address, like effectiveness and adverse events due to improper stimulation.
Ministerio de Economía y Competitividad (TEC2011-22987)
Junta de Castilla y León (VA059U13)
2016-12-14T07:43:22Z
2016-12-14T07:43:22Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1517/13543776.2015.1054094
Expert Opinion on Therapeutic Patents, 2015, vol. 25:9,p. 971-989
1354-3776
http://uvadoc.uva.es/handle/10324/21683
eng
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Taylor & Francis
oai:uvadoc.uva.es:10324/217142021-09-10T09:33:59Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Statistical and Nonlinear Analysis of Oximetry from Respiratory Polygraphy to Assist in the Diagnosis of Sleep Apnea in Children
Álvarez González, Daniel
Gutiérrez Tobal, Gonzalo César
Alonso Álvarez, María Luz
Terán Santos, Joaquín
Campo Matias, Félix del
Hornero Sánchez, Roberto
Sleep Apnea in Children
Producción Científica
Obstructive Sleep Apnea-Hypopnea Syndrome
(OSAHS) is a sleep related breathing disorder that has
important consequences in the health and development of
infants and young children. To enhance the early detection of
OSAHS, we propose a methodology based on automated
analysis of nocturnal blood oxygen saturation (SpO2) from
respiratory polygraphy (RP) at home. A database composed of
50 SpO2 recordings was analyzed. Three signal processing
stages were carried out: (i) feature extraction, where statistical
features and nonlinear measures were computed and combined
with conventional oximetric indexes, (ii) feature selection using
genetic algorithms (GAs), and (iii) feature classification through
logistic regression (LR). Leave-one-out cross-validation (loo-cv)
was applied to assess diagnostic performance. The proposed
method reached 80.8% sensitivity, 79.2% specificity, 80.0%
accuracy and 0.93 area under the ROC curve (AROC), which
improved the performance of single conventional indexes. Our
results suggest that automated analysis of SpO2 recordings from
at-home RP provides essential and complementary information
to assist in OSAHS diagnosis in children.
Ministerio de Economía y Competitividad (TEC2011-22987)
Fundación General CSIC (Proyecto Cero 2011 sobre Envejecimiento)
Obra social de la Caixa y CSIC
Junta de Castilla y León (VA059U13)
2016-12-14T12:04:19Z
2016-12-14T12:04:19Z
2014
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2014.6943972
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014, v. 2014, p. 1860-3
1557-170X
http://uvadoc.uva.es/handle/10324/21714
2014
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217152021-09-10T09:32:55Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Exploring the Spectral Information of Airflow Recordings to Help in Pediatric Obstructive Sleep Apnea-Hypopnea Syndrome Diagnosis
Gutiérrez Tobal, Gonzalo César
Álvarez González, Daniel
Alonso Álvarez, María Luz
Terán Santos, Joaquín
Campo Matias, Félix del
Hornero Sánchez, Roberto
Sleep Apnea-Hypopnea Syndrome Diagnosis
Producción Científica
This work aims at studying the usefulness of
the spectral information contained in airflow (AF) recordings
in the context of Obstructive Sleep Apnea-Hypopnea
Syndrome (OSAHS) in children. To achieve this goal, we
defined two spectral bands of interest related to the
occurrence of apneas and hypopneas. We characterized these
bands by extracting six common spectral features from each
one. Two out of the 12 features reached higher diagnostic
ability than the 3% oxygen desaturation index (ODI3), a
clinical parameter commonly used as screener for OSAHS.
Additionally, the stepwise logistic regression (SLR) featureselection
algorithm showed that the information contained in
the two bands was complementary, both between them and
with ODI3. Finally, the logistic regression method involving
spectral features from the two bands, as well as ODI3,
achieved high diagnostic performance after a bootstrap
validation procedure (84.6±9.6 sensitivity, 87.2±9.1
specificity, 85.8±5.2 accuracy, and 0.969±0.03 area under
ROC curve). These results suggest that the spectral
information from AF is helpful to detect OSAHS in children
Ministerio de Economía y Competitividad (TEC2011-22987)
Junta de Castilla y León (VA059U13)
2016-12-14T12:12:26Z
2016-12-14T12:12:26Z
2014
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2014.6944079
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2014, v. 2014, p. 2298-301
1557-170X)
http://uvadoc.uva.es/handle/10324/21715
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217182021-09-10T09:32:24Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Automated Analysis of Nocturnal Oximetry as Screening Tool for Childhood Obstructive Sleep Apnea-Hypopnea Syndrome
Álvarez González, Daniel
Kheirandish Gozal, Leila
Gutiérrez Tobal, Gonzalo César
Hornero Sánchez, Roberto
Sleep Apnea-Hypopnea Syndrome
Producción Científica
Childhood obstructive sleep apnea-hypopnea
syndrome (OSAHS) is a highly prevalent condition that
negatively affects health, performance and quality of life of
infants and young children. Early detection and treatment
improves neuropsychological and cognitive deficits linked with
the disease. The aim of this study was to assess the performance
of automated analysis of blood oxygen saturation (SpO2)
recordings as a screening tool for OSAHS. As an initial step,
statistical, spectral and nonlinear features were estimated to
compose an initial feature set. Then, fast correlation-based
filter (FCBF) was applied to search for the optimum subset.
Finally, the discrimination power (OSAHS negative vs. OSAHS
positive) of three pattern recognition algorithms was assessed:
linear discriminant analysis (LDA), quadratic discriminant
analysis (QDA) and logistic regression (LR). Three clinical cutoff
points commonly used in the literature for positive diagnosis
of the disease were applied: apnea-hypopnea index (AHI) of 1,
3 and 5 events per hour (e/h). Our methodology reached 88.6%
accuracy (71.4% sensitivity and 100.0% specificity, 100.0%
positive predictive value, and 84.0% negative predictive value)
in an independent test set using QDA for a clinical cut-off point
of 5 e/h. These results suggest that SpO2 nocturnal recordings
may be used to develop a reliable and efficient screening tool
for childhood OSAHS
Junta de Castilla y León (project VA059U13)
2016-12-14T12:18:33Z
2016-12-14T12:18:33Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2015.7318973
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2015, , p. 2800-3
1557-170X
http://uvadoc.uva.es/handle/10324/21718
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217192021-06-23T13:27:37Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Analysis and Classification of Oximetry Recordings to Predict Obstructive Sleep Apnea Severity in Children
Gutiérrez Tobal, Gonzalo César
Kheirandish Gozal, Leila
Álvarez González, Daniel
Crespo Senado, Andrea
Philby, Mona F.
Meelad, Mohammadi
Campo Matias, Félix del
Gozal, David
Hornero Sánchez, Roberto
Sleep Apnea severity in Children
Producción Científica
Current study is focused around the potential use
of oximetry to determine the obstructive sleep apnea-hypopnea
syndrome (OSAHS) severity in children. Single-channel SpO2
recordings from 176 children were divided into three severity
groups according to the apnea-hypopnea index (AHI): AHI<1
events per hour (e/h), 1≤AHI<5 e/h, and AHI ≥5 e/h. Spectral
analysis was conducted to define and characterize a frequency
band of interest in SpO2. Then we combined the spectral data
with the 3% oxygen desaturation index (ODI3) by means of a
multi-layer perceptron (MLP) neural network, in order to
classify children into one of the three OSAHS severity groups.
Following our MLP multiclass approach, a diagnostic protocol
with capability to reduce the need of polysomnography tests by
46% could be derived. Moreover, our proposal can be also
evaluated, in a binary classification task for two common AHI
diagnostic cutoffs (AHI = 1 e/h and AHI= 5 e/h). High
diagnostic ability was reached in both cases (84.7% and 85.8%
accuracy, respectively) outperforming the clinical variable
ODI3 as well as other measures reported in recent studies.
These results suggest that the information contained in SpO2
could be helpful in pediatric OSAHS severity detection.
Junta de Castilla y León (project VA059U13)
2016-12-14T12:34:22Z
2016-12-14T12:34:22Z
2015
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2015.7319404
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2015, p. 4540-3
1557-170X
http://uvadoc.uva.es/handle/10324/21719
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217222021-06-23T13:27:44Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Analysis of Spontaneous EEG Activity in Alzheimer’s Disease Using Cross-Sample Entropy and Graph Theory
Gómez Peña, Carlos
Poza Crespo, Jesús
Gómez Pilar, Javier
Bachiller Matarranz, Alejandro
Juan Cruz, Celia
Tola Arribas, Miguel Ángel
Carreres Rodríguez, Alicia
Cano, Mónica
Hornero Sánchez, Roberto
Entropy
Producción Científica
The aim of this pilot study was to analyze
spontaneous electroencephalography (EEG) activity in
Alzheimer’s disease (AD) by means of Cross-Sample Entropy
(Cross-SampEn) and two local measures derived from graph
theory: clustering coefficient (CC) and characteristic path
length (PL). Five minutes of EEG activity were recorded from
37 patients with dementia due to AD and 29 elderly controls.
Our results showed that Cross-SampEn values were lower in
the AD group than in the control one for all the interactions
among EEG channels. This finding indicates that EEG activity
in AD is characterized by a lower statistical dissimilarity
among channels. Significant differences were found mainly for
fronto-central interactions (p < 0.01, permutation test).
Additionally, the application of graph theory measures
revealed diverse neural network changes, i.e. lower CC and
higher PL values in AD group, leading to a less efficient brain
organization. This study suggests the usefulness of our
approach to provide further insights into the underlying brain
dynamics associated with AD.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (proyecto VA037U16 y BIO/VA08/15)
2016-12-14T12:43:00Z
2016-12-14T12:43:00Z
2016
info:eu-repo/semantics/article
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2016, p. 2830 - 2833
1557-170X
http://uvadoc.uva.es/handle/10324/21722
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217252021-06-23T13:27:27Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Novel Measure of the Weigh Distribution Balance on the Brain Network: Graph Complexity Applied to Schizophrenia
Gómez Pilar, Javier
Bachiller Matarranz, Alejandro
Núñez Novo, Pablo
Poza Crespo, Jesús
Gómez Peña, Carlos
Lubeiro Juárez, Alba
Molina Rodríguez, Vicente
Hornero Sánchez, Roberto
Schizophrenia
Producción Científica
The aim of this study was to assess brain complexity dynamics in schizophrenia (SCH) patients during an auditory oddball task. For that task, we applied a novel graph measure based on the balance of the node weighs distribution. Previous studies applied complexity parameters that were strongly dependent on network topology. This fact could bias the results besides being necessary correction techniques as surrogating process. In the present study, we applied a novel graph complexity measure from the information theory: Shannon Graph Complexity (SGC). Complexity patterns form electroencephalographic recordings of 20 healthy controls and 20 SCH patients during an auditory oddball task were analyzed. Results showed a significantly more pronounced decrease of SGC for controls than for SCH patients during the cognitive task. These findings suggest an important change in the brain configuration towards more balanced networks, mainly in the connections related to long-range interactions. Since these changes are significantly more pronounced in controls, it implies a deficit in the neural network reorganization in SCH patients. In addition, SGC showed a suitable discrimination ability using a leave-one-out cross-validation: 0.725 accuracy and 0.752 area under receiver operating characteristics curve. The novel complexity measure proposed in this study demonstrated to be independent of network topology and, therefore, it complements traditional graph measures to characterize brain networks.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (VA059U13)
2016-12-14T12:52:14Z
2016-12-14T12:52:14Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2016.7590798
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2016, p. 700 - 703
1557-170X
http://uvadoc.uva.es/handle/10324/21725
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217262021-06-23T13:27:47Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Analysis of Magnetoencephalography Signals from Alzheimer’s Disease Patients Using Granger Causality
Juan Cruz, Celia
Gómez Peña, Carlos
Poza Crespo, Jesús
Fernández, Alberto
Hornero Sánchez, Roberto
Alzheimer, Enfermedad de
Producción Científica
The aim of this study was to analyze resting-state
magnetoencephalography (MEG) activity in Alzheimer’s
disease (AD) by means of Granger Causality (GC), an effective
connectivity measure that provides an estimation of the
information flow between brain regions. For this task, five
minutes of MEG recordings were acquired with a 148-channel
whole-head magnetometer from 36 AD patients and 26 healthy
controls. Abnormalities in AD connectivity were found in the
five typical frequency bands: delta (δ, 1-4 Hz), theta (θ, 4-8 Hz),
alpha (α, 8-13 Hz), beta (β, 13-30 Hz), and gamma (γ, 30-65
Hz). Noteworthy increments in delta band and decrements in
beta and gamma bands revealed disrupted connections in AD
brain activity. Our analyses suggest that GC may be useful to
characterize the brain impairment in AD.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (VA059U13 y BIO/VA08/15)
2016-12-14T12:59:10Z
2016-12-14T12:59:10Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2016.7590804
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2016, p. 724 - 727
1557-170X
http://uvadoc.uva.es/handle/10324/21726
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/217442021-06-23T13:27:32Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Analysis of the Non-stationarity of Neural Activity during an Auditory Oddball Task in Schizophrenia
Núñez Novo, Pablo
Poza Crespo, Jesús
Gómez Pilar, Javier
Bachiller Matarranz, Alejandro
Gómez Peña, Carlos
Lubeiro Juárez, Alba
Molina Rodríguez, Vicente
Hornero Sánchez, Roberto
Schizophrenia
Producción Científica
The aim of this study was to characterize brain
dynamics during an auditory oddball task. For this purpose, a
measure of the non-stationarity of a given time-frequency
representation (TFR) was applied to electroencephalographic
(EEG) signals. EEG activity was acquired from 20
schizophrenic (SCH) patients and 20 healthy controls while
they underwent a three-stimulus auditory oddball task. The
Degree of Stationarity (DS), a measure of the non-stationarity
of the TFR, was computed using the continuous wavelet
transform. DS was calculated for both the baseline [-300 0] ms
and active task [150 550] ms windows of a P300 auditory
oddball task. Results showed a statistically significant increase
(p<0.05) in non-stationarity for controls during the cognitive
task in the central region, while less widespread statistically
significant differences were obtained for SCH patients,
especially in the beta-2 and gamma bands. Our findings
support the relevance of DS as a means to study cerebral
processing in SCH. Furthermore, the lack of statistically
significant changes in DS for SCH patients suggests an
abnormal reorganization of neural dynamics during an oddball
task.
Ministerio de Economía y Competitividad (TEC2014-53196-R)
Junta de Castilla y León (VA059U13)
2016-12-15T06:54:56Z
2016-12-15T06:54:56Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1109/EMBC.2016.7591537
Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Annual Conference, 2016, p. 3724 - 3727
1557-170X
http://uvadoc.uva.es/handle/10324/21744
eng
http://ieeexplore.ieee.org/servlet/opac?punumber=1000269
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IEEE Conference Publications
oai:uvadoc.uva.es:10324/239282021-06-23T13:27:52Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Nitrogen-carbon graphite-like semiconductor synthesized from uric acid
Dante, Roberto C.
Chamorro Posada, Pedro
Vázquez Cabo, José
Rubiños López, Óscar
Sánchez Arévalo, Francisco Manuel
Huerta, Lázaro
Martín Ramos, Pablo
Lartundo Rojas, Luis
Ávila Vega, Carlos Fabián
Rivera Tapia, Edgar David
Fajardo Pruna, Cristian
Ávila Vega, Álvaro J.
Solorza Feria, Omar
A new carbon-nitrogen organic semiconductor has been synthesized by pyrolysis of uric acid. This layered carbon-nitrogen material contains imidazole-, pyridine (naphthyridine)- and graphitic-like nitrogen, as evinced by infrared and X-ray photoelectron spectroscopies. Quantum chemistry calculations support that it would consist of a 2D polymeric material held together by hydrogen bonds. Layers are stacked with an interplanar distance between 3.30 and 3.36 Å, as in graphite and coke. Terahertz spectroscopy shows a behavior similar to that of amorphous carbons, such as coke, with non-interacting layers. This material features substantial differences from polymeric carbon nitride, with some characteristics closer to those of nitrogen-doped graphene, in spite of its higher nitrogen content. The direct optical band gap, dependent on the polycondensation temperature, ranges from 2.10 to 2.32 eV. Although in general the degree of crystallinity is low, the material synthesized at 600 °C is composed of globular hollow particles, in which spots with a certain degree of crystallinity can be found.
Junta de Castilla y León Grant VA089U16
2017-06-23T15:40:30Z
2017-06-23T15:40:30Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1016/j.carbon.2017.05.098
Carbon, Septiembre 2017, vol. 121, 368–379
http://uvadoc.uva.es/handle/10324/23928
Nitrogen-carbon graphite-like semiconductor synthesized from uric acid
eng
http://www.sciencedirect.com/science/article/pii/S000862231730564X
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/restrictedAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/239292021-06-23T13:27:54Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Characterization of Microring Filters for Differential Group Delay Applications
Doménech, David
Chamorro Posada, Pedro
Fraile Peláez, Francisco Javier
Erro, María José
Tainta, S.
Muriel, Miguel
Baños, Rocío
Bolten, J.
Kleinjans, H.
Producción Científica
The longitudinal offset technique permits to improve the accuracy of the coupling coefficients of integrated directional couplers and provides designs that can be easily implemented with current fabrication tolerances. In this paper, we address the additional degree of freedom offered by this technology in order to tailor the differential group delay in coupled-resonator optical filters. We present the characterization of several devices exploiting this feature and we discuss their potential applications.
Junta de Castilla y León Regional Grant VA089U16
2017-06-23T15:48:03Z
2017-06-23T15:48:03Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1109/JLT.2017.2707478
Journal of Lightwave Technology, julio 2017, vol. 35, p. 2943 - 2947
http://uvadoc.uva.es/handle/10324/23929
Characterization of Microring Filters for Differential Group Delay Applications
spa
http://ieeexplore.ieee.org/document/7932853/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/restrictedAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
IEEE
application/pdf
IEEE
oai:uvadoc.uva.es:10324/239302021-06-23T13:27:55Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A simple method for estimating the fractal dimension from digital images: The compression dimension
Chamorro Posada, Pedro
Producción Científica
The fractal structure of real world objects is often analyzed using digital images. In this context, the compression fractal dimension is put forward. It provides a simple method for the direct estimation of the dimension of fractals stored as digital image files. The computational scheme can be implemented using readily available free software. Its simplicity also makes it very interesting for introductory elaborations of basic concepts of fractal geometry, complexity, and information theory. A test of the computational scheme using limited-quality images of well-defined fractal sets obtained from the Internet and free software has been performed. Also, a systematic evaluation of the proposed method using computer generated images of the Weierstrass cosine function shows an accuracy comparable to those of the methods most commonly used to estimate the dimension of fractal data sequences applied to the same test problem.
Junta de Castilla y León Regional Grant VA089U16
2017-06-23T16:04:15Z
2017-06-23T16:04:15Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1016/j.chaos.2016.08.002
Chaos, Solitons & Fractals, octubre 2016, vol. 91, p. 562-572
http://uvadoc.uva.es/handle/10324/23930
spa
http://www.sciencedirect.com/science/article/pii/S0960077916302399
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/restrictedAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/248392021-06-23T13:28:04Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Towards teaching as design: Exploring the interplay between full-lifecycle learning design tooling and Teacher Professional Development
Asensio Pérez, Juan Ignacio
Dimitriadis Damoulis, Ioannis
Pozzi, Francesca
Hernández Leo, Davinia
Prieto, Luis P.
Persico, Donatella
Villagrá Sobrino, Sara Lorena
Aprendizaje
Entornos de aprendizaje
Producción Científica
Recent research suggests that training teachers as learning designers helps promote technology enhanced educational innovations. However, little attention has been paid so far to the interplay between the effectiveness of Teacher Professional Development (TPD) instructional models promoting the role of teachers as designers and the capabilities (and pitfalls) of the heterogeneous landscape of available Learning Design (LD) tooling employed to support such TPD. This paper describes a mixed method study that explores the use of a novel Integrated Learning Design Environment (ILDE) for supporting a TPD program on Information and Communication Technologies (ICT) and Collaborative Learning (CL). 36 Adult Education (AE) and Higher Education (HE) in-service teachers, with little experience on both CL and ICT integration, participated in a study encompassing training workshops and follow-up fulllifecycle learning design processes (from initial conceptualization to implementation with a total of 176 students). The findings from our interpretive study showcase the benefits (and required effort) derived from the use of an integrated platform that guides teachers along the main phases of the learning design process, and that automates certain technological setup tasks needed for the classroom enactment. The study also highlights the need for adaptation of the TPD instructional model to the learning curve associated to the LD tooling, and explores its impact on the attitude of teachers towards future adoption of LD practices.
Ministerio de Economía, Industria y Competitividad (Projects TIN2011-28308-C03-02, TIN2014-53199-C3-2-R, TIN2014- 53199-C3-3-R, MDM-2015-0502)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14 and VA082U16)
European Union (project 531262-LLP-2012-ES-KA3-KA3MP)
2017-07-31T09:06:06Z
2017-07-31T09:06:06Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1016/j.compedu.2017.06.011
Asensio-Pérez, J. I., Dimitriadis, Y., Pozzi, F., Hernández-Leo, D., Prieto, L. P., Persico, D., & Villagrá-Sobrino, S. L. Towards teaching as design: Exploring the interplay between full-lifecycle learning design tooling and Teacher Professional Development. Computers & Education. 114:92-116, 2017.
http://uvadoc.uva.es/handle/10324/24839
eng
http://www.sciencedirect.com/science/article/pii/S0360131517301471
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/248402021-06-23T13:28:06Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Using virtual learning environments in bricolage mode for orchestrating learning situations across physical and virtual spaces
Muñoz Cristóbal, Juan Alberto
Gallego Lema, Vanesa
Arribas Cubero, Higinio Francisco
Martínez Monés, Alejandra
Asensio Pérez, Juan Ignacio
Aprendizaje
Entornos de aprendizaje
Realidad virtual
Producción Científica
Teachers usually implement their pedagogical ideas in Virtual Learning Environments (VLEs) in a continuous refinement approach also known as “bricolage”. Recently, different proposals have enabled the ubiquitous access to VLEs, thus extending the bricolage mode of operation to other learning spaces. However, such proposals tend to present several limitations for teachers to orchestrate learning situations conducted across different physical and virtual spaces. This paper presents an evaluation study that involved the across-spaces usage of Moodle in bricolage mode and learning buckets (configurable containers of learning artifacts) in multiple learning situations spanning five months in a course on Physical Education in the Natural Environment for pre-service teachers. The study followed a responsive evaluation model, in which we conducted an anticipatory data reduction using an existing orchestration framework (called “5 + 3 aspects”) for structuring data gathering and analysis. The results showed that learning buckets helped the teachers in the multiple aspects of orchestration, overcoming the limitations of alternative approaches in some specific orchestration aspects: helping the involved teachers to connect different physical and physical spaces, while supporting technologies and activities of their everyday practice, and transferring part of the orchestration load from teachers to students. The results also suggested lines of future improvement, including the awareness of outdoor activities.
Ministerio de Economía, Industria y Competitividad (Project TIN2011-28308-C03-02 and TIN2014-53199-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14 and VA082U16)
2017-07-31T09:17:23Z
2017-07-31T09:17:23Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1016/j.compedu.2017.03.004
Muñoz-Cristóbal, J.A., Gallego-Lema, V., Arribas-Cubero, H.F., Martínez-Monés, A., Asensio-Pérez, J.I. Using virtual learning environments in bricolage mode for orchestrating learning situations across physical and virtual spaces. Computers & Education. 109:233-252, 2017.
http://uvadoc.uva.es/handle/10324/24840
eng
http://www.sciencedirect.com/science/article/pii/S0360131517300520
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/248412021-06-23T13:28:07Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Learning Buckets: Helping Teachers Introduce Flexibility in the Management of Learning Artifacts Across Spaces
Muñoz Cristóbal, Juan Alberto
Asensio Pérez, Juan Ignacio
Martínez Monés, Alejandra
Prieto, Luis P.
Jorrín Abellán, Iván Manuel
Dimitriadis Damoulis, Ioannis
Realidad virtual
Educación
Computación ubicua
Producción Científica
echnology offers rich opportunities for learning across different physical and virtual spaces. However, most of current across-spaces proposals are either highly teacher-centered, inflexible in the students’ self-management of learning artifacts during the enactment, or allow the teacher little/no control of such students’ management of artifacts. Moreover, these proposals tend to be disconnected from the practices and tools that are usual in the classroom. How can we achieve a middle ground between keeping the teacher in control of across-spaces situations and, at the same time, providing students with a degree of flexibility to manage learning artifacts? Aiming to address such challenge we propose the notion of learning bucket, and the Bucket-Server, a system implementing such notion. A learning bucket is a container of learning artifacts which are generated and/or accessed across-spaces by the students during the enactment, according to constraints configured by teachers at design time. The responsive evaluation conducted, based on a feature analysis and a pilot study with experts, suggests that learning buckets can help evolve from teacher- to student-centered approaches, while maintaining the teacher in control of students’ actions. The evaluation also indicates that the Bucket-Server surpasses the support provided by alternative proposals to across-spaces learning.
Ministerio de Economía, Industria y Competitividad (Project TIN2014- 53199-C3-2- R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA277U14)
2017-07-31T09:45:36Z
2017-07-31T09:45:36Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1109/TLT.2017.2693150
Muñoz-Cristóbal, J.A., Asensio-Pérez, J.I., Martínez-Monés, A., Prieto-Santos, L.P., Jorrín-Abellán, I.M., Dimitriadis, Y. Learning Buckets: Helping Teachers Introduce Flexibility in the Management of Learning Artifacts Across Spaces. IEEE Transactions on Learning Technologies. In press. , 2017.
http://uvadoc.uva.es/handle/10324/24841
eng
http://ieeexplore.ieee.org/document/7896594/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Institute of Electrical and Electronics Engineers (IEEE)
oai:uvadoc.uva.es:10324/248422021-10-18T11:46:17Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Monitoring for awareness and reflection in ubiquitous learning environments
Muñoz Cristóbal, Juan Alberto
Rodríguez Triana, María Jesús
Gallego Lema, Vanesa
Arribas Cubero, Higinio Francisco
Asensio Pérez, Juan Ignacio
Martínez Monés, Alejandra
Realidad virtual
Aprendizaje ubicuo
Producción Científica
Despite the educational affordances that ubiquitous learning has shown, it is still hampered by several orchestration difficulties. One of these difficulties is that teachers lose awareness of what the students perform across the multiple technologies and spaces involved. Monitoring can help in such awareness, and it has been highly explored in face-to-face and blended learning. Nevertheless, in ubiquitous learning environments monitoring has been usually limited to activities taking place in a specific type of space (e.g., outdoors). In this paper we propose a monitoring system for ubiquitous learning, which was evaluated in three authentic studies, supporting the participants in the affordable monitoring of learning situations involving web, augmented-physical, and 3D virtual world spaces. The work carried out also helped identify a set of guidelines, which are expected to be useful for researchers and technology developers aiming to provide participants’ support in ubiquitous learning environments.
2017-07-31T09:59:58Z
2017-07-31T09:59:58Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1080/10447318.2017.1331536
Muñoz-Cristóbal, J.A., Rodríguez-Triana, M.J., Gallego-Lema, V., Arribas-Cubero, H.F., Asensio-Pérez, J.I., Martínez-Monés, A. Monitoring for awareness and reflection in ubiquitous learning environments. International Journal of Human-Computer Interaction. In press., 2017
http://uvadoc.uva.es/handle/10324/24842
eng
http://www.tandfonline.com/doi/abs/10.1080/10447318.2017.1331536
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Taylor & Francis
oai:uvadoc.uva.es:10324/249022021-06-23T13:28:10Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Enriching the Web of Data with educational information using We-Share
Ruiz Calleja, Adolfo
Asensio Pérez, Juan Ignacio
Vega Gorgojo, Guillermo
Gómez Sánchez, Eduardo
Bote Lorenzo, Miguel Luis
Alario Hoyos, Carlos
Web social
Tecnología educativa
TIC
Herramientas educaticas
Producción Científica
This paper presents We-Share, a social annotation application that enables educators to publish and retrieve information about educational ICT tools. As a distinctive characteristic, We-Share provides educators data about educational tools already available on the Web of Data while allowing them to enrich such data with their experience using technology in the classroom. We-Share evaluation entails an empirical study where 23 educators enriched tool descriptions available on the Web of Data out of their own experience. The results suggest that experiential annotations published by educators using We-Share improve the satisfaction and confidence of other educators when discovering and selecting ICT tools. Further, most educators found We-Share an easy-to-use application suitable to share and retrieve information about educational ICT tools.
2017-08-18T08:17:33Z
2017-08-18T08:17:33Z
2017
info:eu-repo/semantics/article
http://dx.doi.org/10.19173/irrodl.v18i1.2633
Ruiz-Calleja, A., Asensio-Pérez, J.I., Vega-Gorgojo, G., Gómez-Sánchez, E., Bote-Lorenzo, M.L., Alario-Hoyos, C. Enriching the Web of Data with educational information using We-Share. The International Review of Research in Open and Distributed Learning. 18(1):247-265, February 2017
1492-3831
http://uvadoc.uva.es/handle/10324/24902
International Review of Research in Open and Distributed Learning
eng
http://www.irrodl.org/index.php/irrodl/article/view/2633/4025
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Athabasca University Press
oai:uvadoc.uva.es:10324/249032021-06-23T13:27:56Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Supporting Collaborative Design Activity in a Multi-User Digital Design Ecology
Martínez Maldonado, Roberto
Goodyear, Peter
Carvalho, Lucila
Thompson, Kate
Hernández Leo, Davinia
Dimitriadis Damoulis, Ioannis
Prieto Santos, Luis Pablo
Wardak, Dewa
Aprendizaje
Diseño digital
Producción Científica
Across a broad range of design professions, there has been extensive research on design practices and considerable progress in creating new computer-based systems that support design work. Our research is focused on educational/instructional design for students' learning. In this sub-field, progress has been more limited. In particular, neither research nor systems development have paid much attention to the fact that design is becoming a more collaborative endeavor. This paper reports the latest research outcomes from R&D in the Educational Design Studio (EDS), a facility developed iteratively over four years to support and understand collaborative, real-time, co-present design work. The EDS serves to (i) enhance our scientific understanding of design processes and design cognition and (ii) provide insights into how designers' work can be improved through appropriate technological support. In the study presented here, we introduced a complex, multi-user, digital design tool into the existing ecology of tools and resources available in the EDS. We analysed the activity of four pairs of ‘teacher-designers’ during a design task. We identified different behaviors - in reconfiguring the task, the working methods and toolset usage. Our data provide new insights about the affordances of different digital and analogue design surfaces used in the Studio.
2017-08-18T08:32:57Z
2017-08-18T08:32:57Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1016/j.chb.2017.01.055
Martínez-Maldonado, R., Goodyear, P., Carvalho, L., Thompson, K., Hernández-Leo, D., Dimitriadis, Y., Prieto-Santos, L.P., Wardak, D. Supporting Collaborative Design Activity in a Multi-User Digital Design Ecology. Computers in Human Behavior. 71:327-342, February 2017.
http://uvadoc.uva.es/handle/10324/24903
Computers in Human Behavior.
eng
http://www.sciencedirect.com/science/article/pii/S0747563217300675
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/249042021-06-23T13:27:59Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
La orientación en el medio natural: aprendizaje ubicuo mediante el uso de tecnología
A orientação no ambiente natural: aprendizagem ubíqua através do uso de tecnologia
Orienteering in the natural environment: ubiquitous learning through the use of technology
Gallego Lema, Vanesa
Muñoz Cristóbal, Juan Alberto
Arribas Cubero, Higinio Francisco
Rubia Avi, Bartolomé
Educación superior
Tecnología educativa
Producción Científica
Nuevos estudios emergen en el área de Educación Física, evidenciando que
la tecnología puede potenciar el proceso educativo. Este artículo muestra un proceso
formativo de los contenidos de orientación como actividad física en el medio natural con
apoyo tecnológico. La investigación permitió analizar, siguiendo una metodología de
estudio de caso con 65 estudiantes universitarios y un docente, cómo el aprendizaje ubicuo
a través del uso de herramientas tecnológicas (Realidad Aumentada, geolocalización,
etc.), apoyó el aprendizaje de la orientación en el medio natural. Entre otros resultados,
el aprendizaje ubicuo estimuló el proceso de aprendizaje en distintos espacios físicos
y virtuales, mejoró la adquisición de contenidos de orientación, la competencia digital,
un aprendizaje en distintos momentos, etc. Aparte de estas potencialidades, también se
identificaron problemáticas durante el proceso, como la tensión de que la tecnología no
eclipsara el contacto con el medio natural, la ausencia de red, y otras.
New studies on Physical Education are appearing, showing that technology can
enhance the educational process. This article describes a technology-supported learning
process on orienteering as a physical activity in the natural environment. By using a case
study with 65 university students and one teacher, the research allowed us to analyze
how ubiquitous learning, through the use of technological tools (Augmented Reality,
geolocation, etc.) supported learning of orienteering in the natural environment. Among
other findings, ubiquitous learning stimulated the learning process in different physical and
virtual spaces, better acquisition of orienteering contents, digital competence, and learning
at different times. Apart from these potentialities, some difficulties also emerged during
the process, such as concerns about the dangers of technology overshadowing students’
connections with the natural environment, lack of internet coverage, and others
2017-08-18T08:52:41Z
2017-08-18T08:52:41Z
2017
info:eu-repo/semantics/article
Gallego-Lema, V., Muñoz-Cristóbal, J.A., Arribas-Cubero, H.F., Rubia-Avi, B. Orienteering in the natural environment: Ubiquitous learning through the use of technology. Movimento (ESEFID/UFRGS). 23(2):755-770, 2017
1982-8918
http://uvadoc.uva.es/handle/10324/24904
Movimento
spa
http://www.seer.ufrgs.br/Movimento
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Universidade Federal do Rio Grande do Sul, Brasil
oai:uvadoc.uva.es:10324/249062021-06-23T13:28:02Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Recursos tecnológicos para el aula de Educación Física en el Medio Natural
Gallego Lema, Vanesa
Muñoz Cristóbal, Juan Alberto
Arribas Cubero, Higinio Francisco
Rubia Avi, Bartolomé
Educación física
TICs
Producción Científica
En el artículo presentamos diferentes herramientas tecnológicas utilizadas como recurso en el desarrollo de actividades físicas en el medio natural. Para ello, ofrecemos una descripción, las limitaciones encontradas así como el uso didáctico de aplicaciones basadas en Realidad Aumentada, Geoposición, Redes Sociales y otras.
2017-08-18T09:03:54Z
2017-08-18T09:03:54Z
2017
info:eu-repo/semantics/article
Gallego-Lema, V., Muñoz-Cristóbal, J.A., Arribas-Cubero, H.F., Rubia-Avi, B. Recursos tecnológicos para el aula de Educación Física en el Medio Natural. Revista Tándem: Didáctica de la Educación Física. In press. , 2017.
2014-4768
http://uvadoc.uva.es/handle/10324/24906
spa
http://tandem.grao.com/revistas/tandem
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Editorial Graó
oai:uvadoc.uva.es:10324/249132021-06-23T13:28:03Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Exploring Teachers Perceptions on Modeling Effort Demanded by CSCL Designs with Explicit Artifact Flow Support
Bordiés López, Osmel
Dimitriadis Damoulis, Ioannis
Nuevas tecnologías
Aprendizaje colaborativo
Producción Científica
Artifact flow represents an important aspect of teaching/learning processes, especially in CSCL situations in which complex relationships may be found. However, explicit modeling of CSCL processes with artifact flow may increase the cognitive load and associated effort of the teachers-designers and therefore decrease the efficiency of the design process. The empirical study, reported in this paper and grounded on mixed methods, provides evidence of the effort overload when teachers are involved in designing CSCL situations in a controlled environment. The results of the study illustrate the problem through the subjective perception of the participating teachers, complemented with objective parameters, such as time consumed, errors committed, uncertainty and objective complexity metrics.
Ministerio de Economía, Industria y Competitividad (Project Project TIN2014-53199-C3- 2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14)
Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA082U16)
2017-08-18T10:51:27Z
2017-08-18T10:51:27Z
2016
info:eu-repo/semantics/article
https://doi.org/10.3217/jucs-022-10-1398
Bordiés-López, O., Dimitriadis, Y. Exploring Teachers Perceptions on Modeling Effort Demanded by CSCL Designs with Explicit Artifact Flow Support. Journal of Universal Computer Science. 22(10):1398-1417, October 2016.
http://uvadoc.uva.es/handle/10324/24913
eng
http://www.jucs.org/jucs_22_10/exploring_teachers_perceptions_on
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Graz University of Technology, Institut für Informationssysteme und Computer Medien (IICM)
oai:uvadoc.uva.es:10324/259152021-06-23T13:28:11Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Security Assessment of the Spanish Contactless Identity Card
Rodríguez, Ricardo J.
García Escartín, Juan Carlos
Sanchez Ballabriga, Víctor
The theft of personal information to assume the identity of a person is a common threat.
Individual criminals, terrorists, or crime rings normally do it to commit fraud or other felonies.
Recently, the Spanish identity card, which provides enough information to hire on-line products such as mortgages or loans, was updated to incorporate a Near Field Communication (NFC) chip as electronic passports do. This contactless interface brings a new attack vector for these criminals, who might take advantage of the RFID communication to secretly steal personal information. In this paper, we assess the security of contactless Spanish identity card against identity theft. In particular, we evaluated the resistance of one of the contactless access protocol against brute-force attacks and found that no defenses were incorporated. We suggest how to avoid brute-force attacks. Furthermore, we also analyzed the pseudo-random number generator within the card, which passed all performed tests with good results.
MINECO CyCriSec (TIN2014-58457-R).
University of Zaragoza and Centro Universitario de la Defensa UZCUD2016-TEC-06.
Project TEC2015-69665-R (MINECO/FEDER, UE).
2017-09-25T16:53:01Z
2017-09-25T16:53:01Z
2017
info:eu-repo/semantics/article
http://dx.doi.org/10.1049/iet-ifs.2017.0299
http://dx.doi.org/10.1049/iet-ifs.2017.0299
http://uvadoc.uva.es/handle/10324/25915
eng
info:eu-repo/semantics/restrictedAccess
Institution of Engineering and Technology
application/pdf
IET
oai:uvadoc.uva.es:10324/259632021-06-23T13:28:14Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Helmholtz solitons in diffusive Kerr-type media
Sánchez Curto, Julio
Chamorro Posada, Pedro
Nonlinear interfaces separating two diffusive Kerr-type media exhibit dual switching between total internal reflection and transmission. This property is found within a weakly nonlocal regime when both a nonparaxial treatment of the problem and a full two-dimensional model for carrier diffusion are assumed. The theoretical model is shown to predict an effective cubic-quintic nonlinearity with competing terms that produces such property. The validity of the analysis is contrasted with a full set of numerical simulations.
2017-09-28T09:19:47Z
2017-09-28T09:19:47Z
2016
info:eu-repo/semantics/article
Phys. Rev. A 93, 033826 (2016)
http://uvadoc.uva.es/handle/10324/25963
eng
info:eu-repo/semantics/openAccess
application/pdf
American Physical Society
oai:uvadoc.uva.es:10324/313742021-07-06T08:34:16Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Optimized Diffusion-Weighting Gradient Waveform Design (ODGD) formulation for motion compensation and concomitant gradient nulling
Peña Nogales, Óscar
Zhang, Yuxin
Wang, Xiaoke
Luis García, Rodrigo de
Aja Fernández, Santiago
H. Holmes, James
Hernando, Diego
Diffusion-weighted imaging (DWI)
diffusion-weighting gradient waveforms
optimization
motion compensation
concomitant gradient (CG)-nulling
Producción Científica
Purpose: To present a novel Optimized Diffusion-weighting Gradient waveform Design (ODGD) method for the design of minimum echo time (TE), bulk motion-compensated, and concomitant gradient (CG)-nulling waveforms for diffusion MRI.
Methods: ODGD motion-compensated waveforms were designed for various moment-nullings Mn (n=0,1,2), for a range of b-values, and spatial resolutions, both without (ODGD-Mn) and with CG-nulling (ODGD-Mn-CG). Phantom and in-vivo (brain and liver) experiments were conducted with various ODGD waveforms to compare motion robustness, signal-to-noise ratio (SNR), and apparent diffusion coefficient (ADC) maps with state-of-the-art waveforms.
Results:ODGD-Mn and ODGD-Mn-CG waveforms reduced the TE of state-of-the-art waveforms. This TE reduction resulted in significantly higher SNR (P < 0.05) in both phantom and in-vivo experiments. ODGD-M1 improved the SNR of BIPOLAR (42.8+-5.3 versus 32.9+-3.3) in the brain, and ODGD-M2 the SNR of motion-compensated (MOCO) and Convex Optimized Diffusion Encoding-M2 (CODE-M2) (12.3+-3.6 versus 9.7+-2.9 and 10.2+-3.4, respectively) in the liver. Further, ODGD-M2 also showed excellent motion robustness in the liver. ODGD-M2-CG waveforms reduced the CG-related dephasing effects of non CG-nulling waveforms in phantom and in-vivo experiments, resulting in accurate ADC maps.
Conclusions: ODGD waveforms enable motion-robust diffusion MRI with reduced TEs, increased SNR, and reduced ADC bias compared to state-of-the-art waveforms in theoretical results, simulations, phantoms and in-vivo experiments.
TEC2013-44194-P
VA069U16
2018-09-03T17:31:52Z
2018-09-03T17:31:52Z
2018
info:eu-repo/semantics/article
https://doi.org/10.1002/mrm.27462
Magn. Reson. Med 2018;00:1-15
http://uvadoc.uva.es/handle/10324/31374
eng
info:eu-repo/semantics/openAccess
application/pdf
Wiley
oai:uvadoc.uva.es:10324/313812021-06-23T13:28:16Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Vortical Features for Myocardial Rotation Assessment in Hypertrophic Cardiomyopathy using Cardiac Tagged Magnetic Resonance
Sanz Estébanez, Santiago Rodrigo
Cordero Grande, Lucilio
Sevilla Ruiz, María Teresa
Revilla Orodea, Ana
Luis García, Rodrigo de
Martín Fernández, Marcos Antonio
Alberola López, Carlos
Left ventricular rotational motion is a feature of normal and diseased cardiac function. However, classical torsion and twist measures rely on the definition of a rotational axis which may not exist. This paper re- views global and local rotation descriptors of myocardial motion and introduces new curl-based (vortical) features built from tensorial magnitudes, intended to provide better comprehension about fibrotic tissue characteristics mechanical properties. Fifty-six cardiomyopathy patients and twenty-two healthy volun- teers have been studied using tagged magnetic resonance by means of harmonic phase analysis. Rotation descriptors are built, with no assumption about a regular geometrical model, from different approaches. The extracted vortical features have been tested by means of a sequential cardiomyopathy classification procedure; they have proven useful for the regional characterization of the left ventricular function by showing great separability not only between pathologic and healthy patients but also, and specifically, between heterogeneous phenotypes within cardiomyopathies.
2018-09-03T20:02:51Z
2018-09-03T20:02:51Z
2018
info:eu-repo/semantics/article
Medical Image Analysis, Julio 2018
http://uvadoc.uva.es/handle/10324/31381
spa
Attribution 4.0 International
info:eu-repo/semantics/restrictedAccess
http://creativecommons.org/licenses/by/4.0/
application/pdf
oai:uvadoc.uva.es:10324/313822021-06-23T13:28:17Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Robust Estimation of the Apparent Diffusion Coefficient Invariant to Acquisition Noise and Physiological Motion
Sanz Estébanez, Santiago Rodrigo
Pieciak, Tomasz
Alberola López, Carlos
Aja Fernández, Santiago
Purpose: In this work we have proposed a methodology for the estimation of the apparent diffusion coeffcient in the body from multiple breath hold diffusion weighted images, which is robust to two preeminent confounding factors: noise and motion during acquisition.
Methods: We have extended a method for the joint groupwise multimodal registration and apparent diffusion coefficient estimation, previously proposed by the authors, in order to correct the bias that arises from the non-Gaussianity of the data and the registration procedure.
Results: Results show that the proposed methodology provides a statistically signi ficant improvement both in robustness for displacement elds calculation and in terms of accuracy for the apparent diffusion coefficient estimation as compared with traditional sequential approaches. Reproducibility has also been measured on real data in terms of the distribution of apparent diffusion coefficient differences obtained from different b-values subsets.
Conclusions: Our proposal has shown to be able to effectively correct the estimation bias by introducing additional computationally light procedures to the original method, thus providing robust apparent diffusion coefficient maps in the liver and allowing an accurate and reproducible analysis of the tissue.
2018-09-03T20:08:58Z
2018-09-03T20:08:58Z
2018
info:eu-repo/semantics/article
Magnetic Resonance Imaging, Julio 2018
http://uvadoc.uva.es/handle/10324/31382
spa
Attribution 4.0 International
info:eu-repo/semantics/restrictedAccess
http://creativecommons.org/licenses/by/4.0/
application/pdf
oai:uvadoc.uva.es:10324/314132021-06-24T10:25:59Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Orchestrating learning analytics (OrLA): Supporting inter-stakeholder communication about adoption of learning analytics at the classroom level
Prieto, Luis P.
Rodríguez Triana, María Jesús
Martínez Maldonado, Roberto
Dimitriadis Damoulis, Ioannis
Gašević, Dragan
Aprendizaje
Aula
Producción Científica
Despite the recent surge of interest in learning analytics (LA), their adoption in everyday
classroom practice is still slow. Knowledge gaps and lack of inter-stakeholder communication
(particularly with educational practitioners) have been posited as critical factors for previous
LA adoption failures. Yet, what issues should researchers, practitioners and other actors
communicate about, when considering the adoption of an LA innovation in a particular
context? We reviewed and synthesised existing literature on four focus areas related to LA,
their adoption, implications for practice, and more general factors that have emerged as crucial
when studying everyday classroom adoption of technologies (i.e., classroom orchestration).
This synthesis resulted in two conversational frameworks and an inter-stakeholder
communication tool. These can be used to guide and support conversations and decisionmaking about the adoption of LA innovations. We illustrate their usefulness with examples of use in ongoing LA adoption processes in Australia, Spain and Estonia.
Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA082U16)
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199-C3-2-R and TIN2017-85179-C3-2-R),
Ministerio de Educación, Cultura y Deporte (PRX17/00410)
2018-09-06T07:59:01Z
2018-09-06T07:59:01Z
2018
info:eu-repo/semantics/article
Australasian Journal of Educational Technology (accepted, july 2018)
1449-5554
http://uvadoc.uva.es/handle/10324/31413
eng
https://ajet.org.au/index.php/AJET/index
info:eu-repo/grantAgreement/EC/H2020/669074
info:eu-repo/grantAgreement/EC/H2020/731685
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Australasian Society for Computers in Learning in Tertiary Education
oai:uvadoc.uva.es:10324/314142021-06-23T13:28:23Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Exploring teachers’ needs and the existing barriers to the adoption of Learning Design methods and tools: a literature survey
Dagnino, Francesca Maria
Dimitriadis Damoulis, Ioannis
Rubia Avi, Bartolomé
Pozzi, Francesca
Asensio Pérez, Juan Ignacio
Tecnología de aprendizaje
Diseño de aprendizaje
Producción Científica
Learning Design (LD) is oriented to support teachers in designing their teaching with the aim to
provide a sound pedagogical background and to make effective use of resources and technologies. In spite of the significant number of LD approaches and tools proposed so far, their adoption is still very limited and this represents an unsolved challenge in the field of LD. This paper presents a systematic review of the literature about learning design tools, tackling the issue of adoption from two points of view: teachers’ needs in relation to LD tools and methods and possible barriers to their adoption. The review includes only research papers where teachers’ behaviours and opinions are directly explored and not purely theoretical papers. The search included five main academic databases in Technology Enhanced Learning (TEL) plus a search on Google about project reports; the resulting corpus included 423 papers: 26 of these, plus 3 reports were included in the final list for the analysis. The review provides a systematic overview of the knowledge developed in the LD field, focusing on a set of research gaps that need further exploration in the future.
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199-C3-2-R and TIN2017- 85179-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
European Commission (Proyect 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2018-09-06T08:28:49Z
2018-09-06T08:28:49Z
2018
info:eu-repo/semantics/article
British Journal of Educational Technology (accepted, july 2018)
0007-1013
http://uvadoc.uva.es/handle/10324/31414
eng
https://onlinelibrary.wiley.com/journal/14678535
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Wiley
oai:uvadoc.uva.es:10324/314162021-06-23T13:28:30Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
An approach to build in situ models for the prediction of the decrease of academic engagement indicators in Massive Open Online Courses
Bote Lorenzo, Miguel Luis
Gómez Sánchez, Eduardo
MOOC
Aprendizaje automático
Producción Científica
The early detection of learners who are expected to disengage with typical MOOC tasks such as watching lecture videos or submitting assignments is necessary to enable timely interventions aimed at preventing it. This can be done by predicting the decrease of academic engagement indicators that can be derived for di_erent MOOC tasks and computed for each learner. A posteriori prediction models can yield a good performance but cannot be built using the information that is available in an ongoing course at the moment the predictions are required. This paper proposes an approach to build in situ prediction models using such information. Models were derived following both approaches and employed to predict the decrease of three indicators that quantify the engagement of learners with the main tasks typically proposed in a MOOC: watching lectures, solving _nger exercises, and submitting assignments. The results show that in situ models yielded a good performance for the prediction of all engagement indicators, thus showing the feasibility of the proposed approach. This performance was very similar to that of a posteriori models, which have the clear disadvantage that they cannot be used to make predictions in an ongoing course based on its data.
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199-C3-2-R (AEI, FEDER), TIN2017-85179-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA277U14)
European Commission (Proyect 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2018-09-06T08:47:44Z
2018-09-06T08:47:44Z
2018
info:eu-repo/semantics/article
Journal of Universal Computer Science (accepted 2018)
0948-695X
http://uvadoc.uva.es/handle/10324/31416
eng
http://www.jucs.org/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Graz University of Technology, Institut für Informationssysteme und Computer Medien
oai:uvadoc.uva.es:10324/314192021-06-23T13:28:35Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Supporting Teachers in the Design and Implementation of Group Formation Policies in MOOCs: A Case Study
Sanz Martínez, María Luisa
Er, Erkan
Dimitriadis Damoulis, Ioannis
Martínez Monés, Alejandra
Bote Lorenzo, Miguel Luis
MOOC
Aprendizaje colaborativo
Producción Científica
Collaborative learning strategies, which can promote student learning and achievement, have rarely been incorporated into pedagogies of MOOCs. Such strategies, when implemented properly, can boost the quality of MOOC pedagogy. Nonetheless, the use of collaborative groups in MOOCs is scarce due to several yet critical contextual factors (e.g., massiveness, and variable levels of engagement) that hamper the group formation process.
Therefore, there is a need for supporting MOOC teachers in the design and implementation of group formation policies when implementing collaborative strategies. This paper presents a study where two instruments were used to explore solutions to this need: a guide to support teachers during the planning of the group formation, and a technological tool to help them implement the collaborative groups designed and to monitor them. According to the results of the study, the design guide made the teachers aware of the contextual factors to consider when forming the collaborative groups, and allowed teachers inform some configuration parameters of the activity (e.g., duration and assessment type) and the group formation (e.g., criteria and parameters needed to build the groups). The technological tool was successfully incorporated into the MOOC platform. Lessons learned from the findings of the study are shared and their potential to inform the design guide is discussed.
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199- C3-2-R and TIN2017-85179-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
European Commission (Proyect 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2018-09-06T09:13:50Z
2018-09-06T09:13:50Z
2018
info:eu-repo/semantics/article
Journal of Universal Computer Science (accepted 2018)
http://uvadoc.uva.es/handle/10324/31419
eng
http://www.jucs.org/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Graz University of Technology, Institut für Informationssysteme und Computer Medien
oai:uvadoc.uva.es:10324/314202024-02-02T09:24:00Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A self-scalable distributed network simulation environment based on cloud computing
Serrano Iglesias, Sergio
Gómez Sánchez, Eduardo
Bote Lorenzo, Miguel Luis
Asensio Pérez, Juan Ignacio
Rodríguez Cayetano, Manuel
Simulación por ordenador
Aplicación informática en la nube
Producción Científica
While parameter sweep simulations can help undergraduate students and researchers to understand computer networks, their usage in the academia is hindered by the significant computational load they convey. This paper proposes DNSE3, a service oriented computer network simulator that, deployed in a cloud computing infrastructure, leverages its elasticity and pay-per-use features to compute parameter sweeps. The performance and cost of using this application is evaluated in several experiments applying different scalability policies, with results that meet the demands of users in educational institutions. Additionally, the usability of the application has been measured following industry standards with real students, yielding a very satisfactory user experience.
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199-C3-2-R and TIN2017-85179-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
2018-09-06T09:28:30Z
2018-09-06T09:28:30Z
2018
info:eu-repo/semantics/article
https://doi.org/10.1007/s10586-018-2816-5
Cluster Computing, 2018 (in press)
1386-7857
http://uvadoc.uva.es/handle/10324/31420
eng
https://link.springer.com/article/10.1007/s10586-018-2816-5
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Springer Verlag
oai:uvadoc.uva.es:10324/314212021-06-23T13:28:32Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Clover Quiz: a trivia game powered by DBpedia
Vega Gorgojo, Guillermo
DBpedia
Aplicación móvil
Producción Científica
DBpedia is a large-scale and multilingual knowledge base generated by extracting structured data from Wikipedia. There have been several attempts to use DBpedia to generate questions for trivia games, but these initiatives have not succeeded to produce large, varied, and entertaining question sets. Moreover, latency is too high for an interactive game if questions are created by submitting live queries to the public DBpedia endpoint. These limitations are addressed in Clover Quiz, a turn-based multiplayer trivia game for Android devices with more than 200K multiple choice questions (in English and Spanish) about different domains generated out of DBpedia. Questions are created off-line through a data extraction pipeline and a versatile template-based mechanism. A back-end server manages the question set and the associated images, while a mobile app has been developed and released in Google Play. The game is available free of charge and has been downloaded by more than 5K users since the game was released in March 2017. Players have answered more than 614K questions and the overall rating of the game is 4.3 out of 5.0. Therefore, Clover Quiz demonstrates the advantages of semantic technologies for collecting data and automating the generation of multiple choice questions in a scalable way.
Ministerio de Economía, Industria y Competitividad (Projects TIN2017-85179-C3-2-R and RESET TIN2014-53199-C3-2-
2018-09-06T09:40:43Z
2018-09-06T09:40:43Z
2018
info:eu-repo/semantics/article
Semantic Web, 2018
http://uvadoc.uva.es/handle/10324/31421
eng
http://www.semantic-web-journal.net/content/clover-quiz-trivia-game-powered-dbpedia-0
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
IOS Press
oai:uvadoc.uva.es:10324/314232021-06-23T13:28:24Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Online machine learning algorithms to predict link quality in community wireless mesh networks
Bote Lorenzo, Miguel Luis
Gómez Sánchez, Eduardo
Mediavilla Pastor, Carlos
Asensio Pérez, Juan Ignacio
Aprendizaje automático
Producción Científica
Accurate link quality predictions are key in community wireless mesh networks (CWMNs) to improve the performance of routing protocols. Unlike other techniques, online machine learning algorithms can be used to build link quality predictors that are adaptive without requiring a predeployment effort. However, the use of these algorithms to make link quality predictions in a CWMN has not been previously explored. This paper analyses the performance of 4 well-known online machine learning algorithms for link quality prediction in a CWMN in terms of accuracy and computational load. Based on this study, a new hybrid online algorithm for link quality prediction is proposed. The evaluation of the proposed algorithm using data from a real large scale CWMN shows that it can achieve a high accuracy while generating a low computational load.
Ministerio de Economía, Industria y Competitividad (Project TIN2014-53199-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
2018-09-06T10:27:45Z
2018-09-06T10:27:45Z
2018
info:eu-repo/semantics/article
https://doi.org/10.1016/j.comnet.2018.01.005
Computer Networks Volume 132, 2018, Pages 68-80
1389-1286
http://uvadoc.uva.es/handle/10324/31423
eng
https://www.sciencedirect.com/science/article/pii/S1389128618300069
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/314242021-06-23T13:28:25Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Game of Blazons: Helping teachers conduct learning situations that integrate web tools and multiple types of augmented reality
Muñoz Cristóbal, Juan Alberto
Gallego Lema, Vanesa
Arribas Cubero, Higinio Francisco
Asensio Pérez, Juan Ignacio
Martínez Monés, Alejandra
Tecnologías de aprendizaje
Realidad virtual
Producción Científica
Several studies have explored how to help teachers carry out learning situations involving Augmented Reality (AR), a technology that has shown different affordances for learning. However, these proposals tend to rely on specific types of AR, focus on particular types of spaces, and are generally disconnected from other technologies widely used in education, such as VLEs or Web 2.0 tools. These constraints limit the possible range of activities that can be conducted and their integration into the existing classroom practice. GLUEPS-AR is a system that can help overcome these limitations, aiding teachers in the creation and enactment of learning situations that may combine multiple types of AR with other common web tools. This paper presents an evaluation study conducted on Game of Blazons, a learning situation carried out by two university teachers using GLUEPS-AR, and framed within two days of outdoor activities in a village in Spain. The evaluation showed that GLUEPS-AR provided an affordable support to the participant teachers to integrate several activities that made use of multiple types of AR, common web tools and augmented paper, into a unique learning situation.
Ministerio de Economía, Industria y Competitividad (Projects TIN2011-28308-C03-02 and TIN2014-53199-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
2018-09-06T10:40:56Z
2018-09-06T10:40:56Z
2018
info:eu-repo/semantics/article
http://dx.doi.org/10.1109/TLT.2018.2808491
IEEE Transactions on Learning Technologies, 2018 (in press)
http://uvadoc.uva.es/handle/10324/31424
eng
https://ieeexplore.ieee.org/document/8300658/
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Institute of Electrical and Electronics Engineers (IEEE)
oai:uvadoc.uva.es:10324/314252021-06-23T13:28:37Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
4FAD: A framework for mapping the evolution of artefacts in the learning design process
Muñoz Cristóbal, Juan Alberto
Hernández Leo, Davinia
Carvalho, Lucila
Martínez Maldonado, Roberto
Thompson, Kate
Wardak, Dewa
Goodyear, Peter
Educación
Aprendizaje automático
Producción Científica
A number of researchers have explored the role and nature of design in education, proposing a diverse array of life cycle models. Design plays subtly different roles in each of these models. The learning design research community is shifting its attention from the representation of pedagogical plans to considering design as an ongoing process. As a result, the study of the artefacts generated and used by educational designers is also changing: from a focus on the final designed artefact (the product of the design process) to the many artefacts generated and used by designers at different stages of the design process (e.g., sketches, reflections, drawings, or pictures). However, there is still a dearth of studies exploring the evolution of such artefacts throughout the learning design life cycle. A deeper understanding of these evolutionary processes is needed – to help smooth the transitions between stages in the life cycle. In this paper, we introduce the four-dimensional framework for artefacts in design (4FAD) to generate understanding and facilitate the mapping of the evolution of learning design artefacts. We illustrate the value of the framework by applying it in the analysis of an authentic design case.
Ministerio de Economía, Industria y Competitividad (Projects TIN2011-28308-C03-02, TIN2014-53199-C3-2-R, TIN2014-53199-C3-3-R, TIN2017-85179-C3-2-R, TIN2017-85179-C3-3-R, MDM-2015-0502)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
European Commission (Proyect 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2018-09-06T10:50:38Z
2018-09-06T10:50:38Z
2018
info:eu-repo/semantics/article
https://doi.org/10.14742/ajet.3706
Australasian Journal of Educational Technology, 34(2), 2018
http://uvadoc.uva.es/handle/10324/31425
eng
https://ajet.org.au/index.php/AJET/article/view/3706
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Australasian Society for Computers in Learning in Tertiary Education
oai:uvadoc.uva.es:10324/314262021-06-23T13:28:34Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Analytics for learning design: A layered framework and tools
Hernández Leo, Davinia
Martínez Maldonado, Roberto
Pardo, Abelardo
Muñoz Cristóbal, Juan Alberto
Rodríguez Triana, María Jesús
Aprendizaje
Producción Científica
The field of learning design studies how to support teachers in devising suitable activities for their students to learn. The field of learning analytics explores how data about students' interactions can be used to increase the understanding of learning experiences. Despite its clear synergy, there is only limited and fragmented work exploring the active role that data analytics can play in supporting design for learning. This paper builds on previous research to propose a framework (analytics layers for learning design) that articulates three layers of data analytics—learning analytics, design analytics and community analytics—to support informed decision‐making in learning design. Additionally, a set of tools and experiences are described to illustrate how the different data analytics perspectives proposed by the framework can support learning design processes.
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199-C3-2-R, TIN2014-53199-C3-3-R, TIN2017-85179-C3-2-R, TIN2017-85179-C3-3-R, MDM-2015- 0502)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA082U16)
European Commission (Proyect 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2018-09-06T11:11:00Z
2018-09-06T11:11:00Z
2018
info:eu-repo/semantics/article
https://doi.org/10.1111/bjet.12645
British Journal of Educational Technology, 2018 (in press)
0007-1013
http://uvadoc.uva.es/handle/10324/31426
eng
https://onlinelibrary.wiley.com/doi/abs/10.1111/bjet.12645
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Wiley
oai:uvadoc.uva.es:10324/314272021-06-23T13:28:27Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
An Integrated Environment for Learning Design
Hernández Leo, Davinia
Asensio Pérez, Juan Ignacio
Derntl, Michael
Pozzi, Francesca
Chacón, Jonathan
Prieto, Luis P.
Persico, Donatella
Aprendizaje automático
Tecnologías educativas
Producción Científica
Learning design tools aim at supporting practitioners in their task of creating more innovative and effective computer-supported learning situations. Despite there being a myriad of proposed tools, their use presents challenges that recent studies link with practitioners' varied pedagogical approaches and context restrictions, as well as with barriers to practical application derived from the fact that most tools only cover limited functionality and do not support cooperation between practitioners. In this paper we investigate whether it is possible to provide a flexible community system that supports multiple learning design tasks. We propose an Integrated Learning Design Environment (ILDE), which is a networked system integrating collaboration functions, design editors and middleware that enables deployment of the designed learning situations into Virtual Learning Environments. We describe the iterative user-centered process adopted in the design of ILDE as well as its architecture. The architecture is implemented to show its feasibility and that it is capable of providing the targeted functionality. We also present the results of its use in training workshops with 148 practitioners from five different institutions in vocational training, higher and adult education. Some of the learning designs were deployed in VLEs and enacted with students in real learning situations.
2018-09-06T11:23:32Z
2018-09-06T11:23:32Z
2018
info:eu-repo/semantics/article
https://doi.org/10.3389/fict.2018.00009
Frontiers in ICT, 5:9, 2018
http://uvadoc.uva.es/handle/10324/31427
eng
https://www.frontiersin.org/articles/10.3389/fict.2018.00009/full
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Frontiers Media
oai:uvadoc.uva.es:10324/314282021-06-23T13:28:28Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Uso de la colaboración y la gamificación en MOOC: un análisis exploratorio
García Sastre, Sara
Idrissi-Ghlimi Cao, Miriam
Ortega Arranz, Alejandro
Gómez Sánchez, Eduardo
Cursos online
Gamificación
Producción Científica
Los cursos online masivos y abiertos (MOOC: Massive Open Online Courses) presentan un gran potencial para permitir el acceso a la educación superior a cualquier estudiante de manera gratuita y que tenga la posibilidad de acceder a Internet. Sin embargo, su modelo de enseñanza es habitualmente criticado, y múltiples investigadores defienden la aplicación de pedagogías activas para tratar de alcanzar un mejor aprendizaje, como ya es frecuente en el aula presencial. Las diferencias de contexto en estos cursos, como la heterogeneidad de perfiles, la escala o el asincronismo se argumentan con frecuencia como limitadores. Este artículo presenta la exploración de veinte cursos masivos, en diferentes idiomas, en distintas plataformas y en diversos dominios de conocimiento, con el objetivo de analizar en detalle el uso del aprendizaje colaborativo y de la gamificación en los mencionados cursos. Las evidencias encontradas permiten concluir que, a pesar de que hay una preocupación por fomentar la interacción social, no existe una intención pedagógica en ella; y además, si se produce el aprendizaje colaborativo es de manera espontánea, no buscada como el eje central del proceso en el diseño instruccional. Por otro lado, la gamificación sí está presente como elemento motivador, pero está dirigida fundamentalmente a premiar acciones individuales de los estudiantes, no los logros colectivos. También se observa que las distintas plataformas MOOC frecuentan ser complementadas con otras herramientas para tratar de apoyar la interacción de los participantes y la gamificación
Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA082U16)
Ministerio de Economía, Industria y Competitividad (Projects TIN2014-53199- C3-2-R y TIN2017-85179-C3-2-R)
2018-09-06T11:38:43Z
2018-09-06T11:38:43Z
2018
info:eu-repo/semantics/article
http://dx.doi.org/10.5944/ried.21.2.20410
RIED: Revista Latinoamericana de Educación a Distancia, 2018, 21(2):263-283
http://uvadoc.uva.es/handle/10324/31428
spa
http://revistas.uned.es/index.php/ried/article/view/20410
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Asociación Iberoamericana de Educación Superior a Distancia (AIESAD)
oai:uvadoc.uva.es:10324/314352021-06-23T13:28:30Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Supporting Online Collaborative Design for Teacher Professional Development
Marín Juarros, V.I.
Asensio Pérez, Juan Ignacio
Hernández Leo, Davinia
Villagrá Sobrino, Sara Lorena
García Sastre, Sara
Tecnologías de aprendizaje
Diseño colaborativo
Producción Científica
This paper describes a study on online collaborative design in the context of teacher
professional development. 25 teachers from different Spanish universities and disciplines
participated in the study. The aim was to understand how to support teachers in
interuniversity teams to collaborate fully online along the learning design process of a
discipline-based situation that integrates ICT, a problem scarcely tackled in the literature. The
described interpretive study, using mixed methods, explores the support to online co-design
provided by a novel ICT community platform named ILDE (Integrated Learning Design
Environment). Lessons drawn from the results can contribute to the improvement of online
collaborative design processes in the context of teacher professional development.
2018-09-07T07:25:10Z
2018-09-07T07:25:10Z
2018
info:eu-repo/semantics/article
Technology, Pedagogy and Education, 2018 (in press)
1475-939X
http://uvadoc.uva.es/handle/10324/31435
eng
https://www.tandfonline.com/toc/rtpe20/current
Attribution-NonCommercial-NoDerivatives 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
application/pdf
Taylor & Francis
oai:uvadoc.uva.es:10324/334872021-06-23T13:28:38Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
PID controller based on a self-adaptive neural network to ensure qos bandwidth requirements in passive optical networks
Merayo Álvarez, Noemí
Juárez Estévez, David
Aguado Manzano, Juan Carlos
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Red neuronal (NN)
Red óptica pasiva (PON)
Neural network (NN)
Passive optical network (PON)
Producción Científica
In this paper, a proportional-integral-derivative (PID) controller integrated with a neural network (NN) is proposed to ensure quality of service (QoS) bandwidth requirements in passive optical networks (PONs). To the best of our knowledge, this is the first time an approach that implements a NN to tune a PID to deal with QoS in PONs is used. In contrast to other tuning techniques such as Ziegler-Nichols or genetic algorithms (GA), our proposal allows a real-time adjustment of the tuning parameters according to the network conditions. Thus, the new algorithm provides an online control of the tuning process unlike the ZN and GA techniques, whose tuning parameters are calculated offline. The algorithm, called neural network service level PID (NNSPID), guarantees minimum bandwidth levels to users depending on their service level agreement, and it is compared with a tuning technique based on genetic algorithms (GASPID). The simulation study demonstrates that NN-SPID continuously adapts the tuning parameters, achieving lower fluctuations than GA-SPID in the allocation process. As a consequence, it provides a more stable response than GA-SPID since it needs to launch the GA to obtain new tuning values. Furthermore, NN-SPID guarantees the minimum bandwidth levels faster than GA-SPID. Finally, NN-SPID is more robust than GA-SPID under real-time changes of the guaranteed bandwidth levels, as GA-SPID shows high fluctuations in the allocated bandwidth, especially just after any change is made.
Ministerio de Ciencia e Innovación (Projects TEC2014-53071-C3-2-P and TEC2015-71932-REDT)
2018-12-17T12:29:02Z
2018-12-17T12:29:02Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1364/JOCN.9.000433
IEEE/OSA Journal of Optical Communications and Networking, 2017, Volume 9, Issue 5, pp. 433 - 445
1943-0639
http://uvadoc.uva.es/handle/10324/33487
eng
https://ieeexplore.ieee.org/document/7926828
info:eu-repo/semantics/openAccess
© 2017 Optical Society of America
application/pdf
Institute of Electrical and Electronics Engineers (IEEE)
oai:uvadoc.uva.es:10324/334892022-06-28T11:40:36Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Fair bandwidth allocation algorithm for PONS based on network utility maximization
Merayo Álvarez, Noemí
Pavón Marino, Pablo
Aguado Manzano, Juan Carlos
Durán Barroso, Ramón José
Burrull i Mestres, Francesc
Bueno Delgado, María Victoria
Asignación dinámica de ancho de banda (DBA)
Red óptica pasiva (PON)
Dynamic bandwidth allocation (DBA)
Passive optical network (PON)
Producción Científica
Network utility maximization (NUM) models have been successfully applied to address multiple resource- allocation problems in communication networks. This paper explores, for the first time to our knowledge, their application to modeling the bandwidth-allocation problem in passive optical networks (PONs) and long-reach PONs. Using the NUM model, we propose the FEx-DBA (fair excess-dynamic bandwidth allocation) algorithm, a new DBA scheme to allow a fair and efficient allocation of the upstream channel capacity. The NUM framework provides the mathematical support to formally define the fairness concept in the resource allocation and the guidelines to devise FEx-DBA. A simulation study is conducted, whereby FEx-DBA is compared to a state-of-the-art proposal. We show that FEx-DBA (i) provides bandwidth guarantees to the users according to the service level agreement (SLA) contracted and fairly distributes the excess bandwidths among them; (ii) has a stable response and fast convergence when traffic or SLAs change, avoiding the oscillations appearing in other proposals; (iii) improves average delay and jitter measures; and (iv) only depends on a reduced set of parameters, which can be easily tuned.
Ministerio de Ciencia e Innovación (Projects TEC2014-53071-C3-2-P and TEC2015-71932-REDT)
2018-12-17T12:37:46Z
2018-12-17T12:37:46Z
2017
info:eu-repo/semantics/article
https://doi.org/10.1364/JOCN.9.000075
IEEE/OSA Journal of Optical Communications and Networking, 2017, Volume 9 , Issue 1, pp. 75 - 86
1943-0639
http://uvadoc.uva.es/handle/10324/33489
eng
https://ieeexplore.ieee.org/document/7830276
info:eu-repo/semantics/openAccess
© 2017 Optical Society of America
application/pdf
Institute of Electrical and Electronics Engineers (IEEE)
oai:uvadoc.uva.es:10324/334902021-06-23T13:28:42Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Experimental assessment of a cognitive mechanism to reduce the impact of outdated TEDs in optical networks
Durán Barroso, Ramón José
Fernández, Natalia
Siracusa, Domenico
Francescon, Antonio
Miguel Jiménez, Ignacio de
Rodríguez, Ignacio
Aguado Manzano, Juan Carlos
Salvadori, Elio
Lorenzo Toledo, Rubén Mateo
Redes ópticas
Optical networks
Producción Científica
We have recently proposed and demonstrated, by means of simulation, the benefits of a simple yet effective cognitive technique to enhance stateless Path Computation Element algorithms with the aim of reducing the connection blocking probability when relying on a potentially non-up-to-date traffic engineering database. In this paper, we employ that technique, called elapsed time matrix (ETM), in the framework of the CHRON (Cognitive Heterogeneous Reconfigurable Optical Network) architecture and, more importantly, validate and analyze its performance in an emulation environment (rather than in a simulation environment) supporting impairment-aware lightpath establishment. Not only dynamic lightpath establishment on demand has been studied, but also restoration processes when facing optical link failures. Emulation results demonstrate that ETM reduces the blocking probability when establishing lightpaths on demand, and increases the percentage of successful restorations in case of optical link failure. Moreover, the use of that technique has little impact on lightpath setup time and lightpath restoration time, respectively.
Ministerio de Ciencia e Innovación (Projects TEC2010-21178-C02-02 and TEC2014-53071-C3-2-P)
European Community’s Seventh Framework Programme [FP7/2007-2013] CHRON project (Cognitive Heterogeneous Reconfigurable Optical Network) under grant agreement no 258644
2018-12-17T12:50:18Z
2018-12-17T12:50:18Z
2016
info:eu-repo/semantics/article
https://doi.org/10.1007/s11107-015-0562-7
Photonic Network Communications, 2016, Volume 31, Issue 2, pp. 259–271
1572-8188
http://uvadoc.uva.es/handle/10324/33490
eng
https://link.springer.com/article/10.1007/s11107-015-0562-7
info:eu-repo/grantAgreement/EC/FP7/258644
info:eu-repo/semantics/openAccess
application/pdf
Springer
oai:uvadoc.uva.es:10324/335602022-04-25T07:40:06Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A Genetic Algorithm for VNF Provisioning in NFV-Enabled Cloud/MEC RAN Architectures
Ruiz Pérez, Lidia
Durán Barroso, Ramón José
Miguel Jiménez, Ignacio de
Khodashenas, Pouria S.
Pedreno Manresa, José Juan
Merayo Álvarez, Noemí
Aguado Manzano, Juan Carlos
Pavón Marino, Pablo
Siddiqui, Shuaib
Mata, Javier
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Redes ópticas
Optical networks
Producción Científica
5G technologies promise to bring new network and service capacities and are expected to introduce significant architectural and service deployment transformations. The Cloud-Radio Access Networks (C-RAN) architecture, enabled by the combination of Software Defined Networking (SDN), Network Function Virtualization (NFV) and Mobile Edge Computing (MEC) technologies, play a key role in the development of 5G. In this context, this paper addresses the problems of Virtual Network Functions (VNF) provisioning (VNF-placement and service chain allocation) in a 5G network. In order to solve that problem, we propose a genetic algorithm that, considering both computing resources and optical network capacity, minimizes both the service blocking rate and CPU usage. In addition, we present an algorithm extension that adds a learning stage and evaluate the algorithm performance benefits in those scenarios where VNF allocations can be reconfigured. Results reveal and quantify the advantages of reconfiguring the VNF mapping depending on the current demands. Our methods outperform previous proposals in the literature, reducing the service blocking ratio while saving energy by reducing the number of active core CPUs.
Ministerio de Economía, Industria y Competitividad (projects TEC2014-53071-C3-2-P, TEC2017-84423-C3-1-P and TEC2015-71932-REDT)
Ministerio de Educación, Cultura y Deporte (projects BES-2015-074514 and FPU14/04227)
2018-12-19T10:49:30Z
2018-12-19T10:49:30Z
2018
info:eu-repo/semantics/article
https://doi.org/10.3390/app8122614
Applied Sciences, 2018, vol. 8, n. 12, 2614
2076-3417
http://uvadoc.uva.es/handle/10324/33560
eng
https://www.mdpi.com/2076-3417/8/12/2614
info:eu-repo/grantAgreement/EC/H2020/761727
Attribution 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
application/pdf
MDPI
oai:uvadoc.uva.es:10324/335622021-06-23T13:28:45Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Artificial intelligence (AI) methods in optical networks: A comprehensive survey
Mata, Javier
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Merayo Álvarez, Noemí
Kumar Singh, Sandeep
Jukan, Admela
Chamania, Mohit
Red óptica
Inteligencia artificial
Optical network
Artificial intelligence
Producción Científica
Artificial intelligence (AI) is an extensive scientific discipline which enables computer systems to solve problems by emulating complex biological processes such as learning, reasoning and self-correction. This paper presents a comprehensive review of the application of AI techniques for improving performance of optical communication systems and networks. The use of AI-based techniques is first studied in applications related to optical transmission, ranging from the characterization and operation of network components to performance monitoring, mitigation of nonlinearities, and quality of transmission estimation. Then, applications related to optical network control and management are also reviewed, including topics like optical network planning and operation in both transport and access networks. Finally, the paper also presents a summary of opportunities and challenges in optical networking where AI is expected to play a key role in the near future.
Ministerio de Economía, Industria y Competitividad (Project EC2014-53071-C3-2-P, TEC2015-71932-REDT)
2018-12-19T11:04:00Z
2018-12-19T11:04:00Z
2018
info:eu-repo/semantics/article
https://doi.org/10.1016/j.osn.2017.12.006
Optical Switching and Networking, 2018, Volume 28, Pages 43-57
http://uvadoc.uva.es/handle/10324/33562
eng
https://www.sciencedirect.com/science/article/pii/S157342771730231X
Attribution 4.0 International
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/386282021-06-23T13:28:46Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Understanding student behavior and perceptions toward earning badges in a gamified MOOC
Ortega Arranz, Alejandro
Er, Erkan
Martínez Monés, Alejandra
Bote Lorenzo, Miguel Luis
Asensio Pérez, Juan Ignacio
Muñoz Cristóbal, Juan Alberto
Gamification
MOOC
Producción Científica
Despite the advantages of MOOCs, such as the open and free access to education, these courses are criticized for students’ lack of motivation and their high dropout rates. Gamification is a technique used to increase student motivation and engagement in small-scale educational contexts. However, the effects of gamification on student engagement have been scarcely explored in MOOC environments, and the findings so far are inconsistent. To address this gap, this research work examines the students’ behavior toward earning badges and how it relates to their engagement in a gamified MOOC. According to the results, the behaviors toward badges of the active students were generally positive and significantly correlated with other variables measuring their engagement (e.g., pageviews, submitted tasks, forum posts), although this positive behavior seems to decrease throughout the course. Additionally, students that reported high motivation by badges at the end of the course showed a higher engagement level than those that were not appealed by badges.
European Regional Development Fund, under project grants TIN2014-53199-C3-2-R and TIN2017-85179-C3-2-R
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. Project VA082U16 and VA257P18)
European Commission, under project grant 588438-EPP-1-2017-1-EL-EPPKA2-KA.
2019-10-17T11:14:46Z
2019-10-17T11:14:46Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
https://doi.org/10.1007/s10209-019-00677-8
Universal Access in the Information Society, 2019, Issue 3
1615-5289
http://uvadoc.uva.es/handle/10324/38628
533
3
549
Universal Access in the Information Society
18
1615-5297
eng
https://www.springerprofessional.de/en/understanding-student-behavior-and-perceptions-toward-earning-ba/16971112
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Springer
application/pdf
Springer Verlag
oai:uvadoc.uva.es:10324/386312021-06-23T13:28:48Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Aligning learning design and learning analytics through instructor involvement: a MOOC case study
Er, Erkan
Gómez Sánchez, Eduardo
Dimitriadis Damoulis, Ioannis
Bote Lorenzo, Miguel Luis
Asensio Pérez, Juan Ignacio
Álvarez Álvarez, Susana
MOOC
Learning design
Producción Científica
This paper presents the findings of a mixed-methods research that explored the potentials emerging from aligning learning design (LD) and learning analytics (LA) during the design of a predictive analytics solution and from involving the instructors in the design process. The context was a past massive open online course, where the learner data and the instructors were accessible for posterior analysis and additional data collection. Through a close collaboration with the instructors, the details of the prediction task were identified, such as the target variable to predict and the practical constraints to consider. Two predictive models were built: LD-specific model (with features based on the LD and pedagogical intentions), and a generic model (with cumulative features, not informed by the LD). Although the LD-specific predictive model did not outperform the generic one, some LD-driven features were powerful. The quantity and the power of such features were associated with the degree to which the students acted as guided by the LD and pedagogical intentions. The leading instructor’s opinion about the importance of the learning activities in the LD was compared with the results of the feature importance analysis. This comparison helped identify the problems in the LD. The implications for improving the LD are discussed.
Ministerio de Ciencia e Innovación (Proyect grants TIN2017-85179-C3-2-R and TIN2014-53199-C3-2-R)
Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. Project VA257P18)
European Commission under project grant 588438-EPP-1-2017-1-EL-EPPKA2-KA
European Union’s Horizon 2020 under the Marie Sklodowska-Curie grant agreement 793317
2019-10-17T11:31:59Z
2019-10-17T11:31:59Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
https://doi.org/10.1080/10494820.2019.1610455
Interactive Learning Environments Volume 27, 2019 - Issue 5-6: The new potentials for Intelligent Tutoring with learning analytics
1049-4820
http://uvadoc.uva.es/handle/10324/38631
685
5-6
698
Interactive Learning Environments
27
1744-5191
eng
https://www.tandfonline.com/doi/abs/10.1080/10494820.2019.1610455?journalCode=nile20
info:eu-repo/grantAgreement/EC/H2020/793317
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Taylor & Francis
application/pdf
Taylor & Francis
oai:uvadoc.uva.es:10324/386482021-06-23T13:28:49Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
To reward and beyond: Analyzing the effect of reward-basedstrategies in a MOOC
Ortega Arranz, Alejandro
Bote Lorenzo, Miguel Luis
Asensio Pérez, Juan Ignacio
Martínez Monés, Alejandra
Gómez Sánchez, Eduardo
Dimitriadis Damoulis, Ioannis
Gamification
Gamificación
MOOC (Massive Open Online Course)
CEMA (Curso En Línea Masivo y Abierto)
Engagement
Compromiso
Retention
Retención
Between-subjects design
Diseño entre sujetos
Producción Científica
Despite the benefits of MOOCs (e.g., open access to education offered by prestigious universities), the low level of student engagement remains as an important issue causing massive dropouts in such courses. The use of reward-based gamification strategies is one approach to promote student engagement and prevent dropout. However, there is a lack of solid empirical studies analyzing the effects of rewards in MOOC environments. This paper reports a between-subjects design study conducted in a MOOC to analyze the effects of badges and redeemable rewards on student retention and engagement. Results show that the implemented reward strategies had not significant effect on student retention and behavioral engagement measured through the number of pageviews, task submissions, and student activity time. However, it was found that learners able to earn badges and redeemable rewards participated more in gamified tasks than those learners in the control group. Additionally, results reveal that the participants in the redeemable reward condition requested and earned earlier the rewards than those participants in the badge condition. The potential implications of these findings in the instructional design of future gamified MOOCs are also discussed.
Ministerio de Ciencia, Innovación y Universidades (projects TIN2017-85179-C3-2-R / TIN2014-53199-C3-2-R)
Junta de Castilla y León (project VA257P18)
European Commission (project 588438-EPP-1-2017-1-EL- EPPKA2-KA)
2019-10-21T08:53:22Z
2019-10-21T08:53:22Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
https://doi.org/10.1016/j.compedu.2019.103639
Computers & Education, 2019, vol. 142. 14 p.
0360-1315
http://uvadoc.uva.es/handle/10324/38648
eng
https://www.sciencedirect.com/science/article/pii/S0360131519301927
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/386492021-06-23T13:28:49Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Creating collaborative groups in a MOOC: a homogeneous engagement grouping approach
Sanz Martínez, María Luisa
Er, Erkan
Martínez Monés, Alejandra
Dimitriadis Damoulis, Ioannis
Bote Lorenzo, Miguel Luis
Automatic group formation
Formación automática de grupos
MOOC (Massive Open Online Course)
CEMA (Curso En Línea Masivo y Abierto)
Collaborative learning
Aprendizaje colaborativo
Engagement
Compromiso
Homogeneous grouping
Agrupamiento homogéneo
Producción Científica
Collaborative learning can improve the pedagogical effectiveness of MOOCs. Group formation, an essential step in the design of collaborative learning activities, can be challenging in MOOCs given the scale and the wide variety in such contexts. We discuss the need for considering the behaviours of the students in the course to form groups in MOOC contexts, and propose a grouping approach that employs homogeneity in terms of students’ engagement in the course. Two grouping strategies with different degrees of homogeneity are derived from this approach, and their impact to form successful groups is examined in a real MOOC context. The grouping criteria were established using student activity logs (e.g. page-views). The role of the timing of grouping was also examined by carrying out the intervention once in the first and once in the second half of the course. The results indicate that in both interventions, the groups formed with a greater degree of homogeneity had higher rates of task-completion and peer interactions, Additionally, students from these groups reported higher levels of satisfaction with their group experiences. On the other hand, a consistent improvement of all indicators was observed in the second intervention, since student engagement becomes more stable later in the course.
Agencia Estatal de Investigación Española - Fondo Europeo de Desarrollo Regional (grants TIN2017-85179-C3-2-R / TIN2014-53199-C3-2-R
Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (grant VA257P18)
Comisión Europea (grant 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2019-10-21T09:12:00Z
2019-10-21T09:12:00Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
https://doi.org/10.1080/0144929X.2019.1571109
Journal Behaviour & Information Technology, 2019, vol. 38, n. 1. p. 1107-1121
0144-929X
http://uvadoc.uva.es/handle/10324/38649
eng
https://www.tandfonline.com/doi/full/10.1080/0144929X.2019.1571109
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Informa UK Limited
application/pdf
Taylor & Francis Group
oai:uvadoc.uva.es:10324/386552021-06-23T13:28:51Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Generating actionable predictions regarding MOOC learners’ engagement in peer reviews
Er, Erkan
Gómez Sánchez, Eduardo
Bote Lorenzo, Miguel Luis
Dimitriadis Damoulis, Ioannis
Asensio Pérez, Juan Ignacio
Engagement prediction
Predicción del compromiso
MOOC (Massive Open Online Course)
CEMA (Curso En Línea Masivo y Abierto)
Peer review
Revisión por pares
In situ learning
Aprendizaje in situ
Producción Científica
Peer review is one approach to facilitate formative feedback exchange in MOOCs; however, it is often undermined by low participation. To support effective implementation of peer reviews in MOOCs, this research work proposes several predictive models to accurately classify learners according to their expected engagement levels in an upcoming peer-review activity, which offers various pedagogical utilities (e.g. improving peer reviews and collaborative learning activities). Two approaches were used for training the models: in situ learning (in which an engagement indicator available at the time of the predictions is used as a proxy label to train a model within the same course) and transfer across courses (in which a model is trained using labels obtained from past course data). These techniques allowed producing predictions that are actionable by the instructor while the course still continues, which is not possible with post-hoc approaches requiring the use of true labels. According to the results, both transfer across courses and in situ learning approaches have produced predictions that were actionable yet as accurate as those obtained with cross validation, suggesting that they deserve further attention to create impact in MOOCs with real-world interventions. Potential pedagogical uses of the predictions were illustrated with several examples.
European Union’s Horizon 2020 research and innovation programme (Marie Sklodowska-Curie grant 793317)
Ministerio de Ciencia, Innovación y Universidades (projects TIN2017-85179-C3-2-R / TIN2014-53199-C3-2-R)
Junta de Castilla y León (grant VA257P18)
Comisión Europea (grant 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2019-10-21T10:20:44Z
2019-10-21T10:20:44Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
https://doi.org/10.1080/0144929X.2019.1669222
Behaviour & Information Technology, in press, 2019
1362-3001
http://uvadoc.uva.es/handle/10324/38655
eng
https://www.tandfonline.com/doi/full/10.1080/0144929X.2019.1669222
info:eu-repo/grantAgreement/EC/H2020/793317
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Informa UK Limited
application/pdf
Taylor & Francis Group
oai:uvadoc.uva.es:10324/386602021-06-23T13:28:52Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Towards the Enactment of Learning Situations Connecting Formal and Non-Formal Learning in SLEs
Serrano Iglesias, Sergio
Bote Lorenzo, Miguel Luis
Gómez Sánchez, Eduardo
Asensio Pérez, Juan Ignacio
Vega Gorgojo, Guillermo
Smart Learning Environments
Entornos Inteligentes de Aprendizaje
Formal learning
Aprendizaje formal
Non-formal learning
Aprendizaje no formal
Producción Científica
Smart Learning Environments hold promise of adapting learning processes to the individual context of students and connecting formal with non-formal learning. To do so, SLEs need to know the current context of the students, regardless of the physical or virtual space where learning takes place. This paper presents an architecture that assists in the deployment and enactment of learning situations across-spaces, able to sense and react to changes in the students’ context in order to adapt the learning process.
ICSLE 2019: International Conference on Smart Learning Environments
Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (projects TIN2014-53199-C3-2-R / TIN2017-85179-C3-2-R)
Comisión Europea (project 588438-EPP-1-2017-1-EL-EPPKA2-KA)
2019-10-21T10:44:58Z
2019-10-21T10:44:58Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/draft
https://doi.org/10.1007/978-981-13-6908-7_27
Chang M. et al. (eds) Foundations and Trends in Smart Learning. Lecture Notes in Educational Technology. Proceedings of 2019 International Conference on Smart Learning Environments, Springer, Singapore, pp 187-190
2196-4971
http://uvadoc.uva.es/handle/10324/38660
eng
https://link.springer.com/chapter/10.1007/978-981-13-6908-7_27
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Springer Nature
application/pdf
Springer Link
oai:uvadoc.uva.es:10324/386642021-06-23T13:28:53Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Reflexiones para la introducción de Colaboración y Gamificación en MOOC
García Sastre, Sara
Ortega Arranz, Alejandro
Gómez Sánchez, Eduardo
Villagrá Sobrino, Sara Lorena
CEMA (Curso En Línea Masivo y Abierto)
MOOC (Massive Open Online Course)
Gamificación
Gamification
Colaboración
Collaboration
Formación
Formation
Enseñanza Universitaria
Higher Education
Producción Científica
Los MOOC (Massive Open Online Courses) siguen irrumpiendo en contextos universitarios de manera significativa. De forma mayoritaria, estos cursos se ofrecen como formación y aprendizaje de acceso universal, propiciando nuevos desafíos en la enseñanza y en sus planteamientos pedagógicos. A pesar de los beneficios de los MOOC en Educación Superior (p.ej. acceso gratuito y ubicuo a la educación), este tipo de cursos son frecuentemente criticados por su modelo de enseñanza centrado en el contenido. De este modo, la aplicación de pedagogías activas se presenta como una posible estrategia para intentar cambiar ese modelo y fomentar la participación de los estudiantes y mejorar las tasas de abandono. Así, el presente trabajo estudia los posibles beneficios de la gamificación y la colaboración para fomentar y motivar la participación de los estudiantes en los MOOC. Para ello, se ha optado por una metodología de investigación enfocada al diseño denominada Design-Based Research (DBR) con la intención de mostrar las evidencias de innovaciones pedagógicas que se han realizado en los diseños de tres MOOC llevados a cabo por la Universidad de Valladolid (España). Los resultados obtenidos en este proceso muestran el potencial de estas técnicas de colaboración y gamificación en MOOC considerando durante el diseño y/o rediseño algunos aspectos importantes para obtener los beneficios deseados.
Junta de Castilla y León - Fondo Europeo de Desarrollo Regional (project VA257P18)
Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (projects TIN2014-53199-C3-2-R / TIN2017-85179-C3-2-R)
Comisión Europea (project 88438-EPP-1-2017-1-EL-EPPKA2-KA)
2019-10-21T13:16:15Z
2019-10-21T13:16:15Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.17398/1695-288X.18.1.163
RELATEC: Revista Latinoamericana de Tecnología Educativa, 2019, vol. 18, n. 1. p. 163-174
1695-288X
http://uvadoc.uva.es/handle/10324/38664
spa
https://relatec.unex.es/article/view/3381
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2019 Universidad de Extremadura
application/pdf
Universidad de Extremadura
oai:uvadoc.uva.es:10324/427902021-06-23T13:28:54Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
An Experimental SDN Proposal over Legacy GPONs to Allow Real-Time Service and Residential Network Reconfiguration
Merayo Álvarez, Noemí
Pintos, David de
Aguado Manzano, Juan Carlos
Durán Barroso, Ramón José
Miguel Jiménez, Ignacio de
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Redes ópticas pasivas
passive optical networks
3325 Tecnología de las Telecomunicaciones
Producción Científica
In this paper we propose an experimental SDN (Software Defined Networking) solution over legacy GPON (Gigabit Passive Optical Network) equipment that allow a control of the network configuration and its services. On the one hand, the proposal permits to move certain global bandwidth and service configuration policies outside the GPON so that they can be managed centrally by an SDN controller. In legacy PONs the real-time bandwidth allocation process is made inside the network infrastructure cycle by cycle between the OLT (Optical Line Terminal) and the ONTs (Optical Network Terminals) so the network performance could be adversely affected due to the latency between the SDN controller and the PON. In contrast, the control of some global DBA strategies by SDN techniques could lead to better network and management configuration and therefore our proposal is able to dynamically adjust these policies according to the real-time Quality of Service (QoS) requirements of residential users. On the other hand, the designed SDN proposal permits network subscribers to control the performance of their residential homes. In this way, they can set constraints and dynamically customize the bandwidth of their connected devices in a very transparent and efficient way.
Junta de Castilla y León (Project VA085G19)
Ministerio de Economía, Industria y Competitividad (Project TEC2017-84423-C3-1-P)
INTERREG V-A España-Portugal (POCTEP) program (0677_DISRUPTIVE_2_E)
2020-10-07T06:52:30Z
2020-10-07T06:52:30Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/draft
https://doi.org/10.1109/ICTON51198.2020.9203432
2020 22nd International Conference on Transparent Optical Networks (ICTON). Bari, Italy, 2020
http://uvadoc.uva.es/handle/10324/42790
1
4
eng
https://ieeexplore.ieee.org/document/9203432
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2020 IEEE
application/pdf
IEEE
oai:uvadoc.uva.es:10324/479622021-08-23T20:47:43Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
On the first order dynamics of subphonon lifetime transient stimulated Brillouin scattering
Chamorro Posada, Pedro
Bengoechea de la Llera, J.
Brillouin scattering
Dispersión de Brillouin
Nonlinear optics
Óptica no lineal
Producción Científica
In this work, we address the phonon dynamics in the stimulated Brillouin scattering process. There exists a wide consensus on the fact that the slowly varying approximation for the acoustic field cannot be invoked in the transient subphonon regime. We present an analysis where we set the precise limits of validity of this approximation. Our study shows that the resonant behavior of the Stokes interaction permits, in general, a first order treatment of this process in the theoretical analysis of current practical applications. An improved-accuracy first order model is also put forward. Numerical calculations are used to support our conclusions.
Junta de Castilla y León (project VA296P18)
2021-08-23T07:30:05Z
2021-08-23T07:30:05Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.yofte.2021.102592
Optical Fiber Technology, 2021, vol. 65, 102592
1068-5200
https://uvadoc.uva.es/handle/10324/47962
eng
https://www.sciencedirect.com/science/article/pii/S1068520021001413?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/480342021-08-24T20:48:11Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Experimental validation of an SDN residential network management proposal over a GPON testbed
Merayo Álvarez, Noemí
Pintos Lumbreras, David de
Aguado Manzano, Juan Carlos
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Software defined networking
Redes definidas por software
GPONs
Experimental validation
Validación experimental
Producción Científica
We propose, and experimentally demonstrate, an SDN (Software Defined Networking) new management solution for legacy GPONs (Gigabit Passive Optical Networks), which allows users to dynamically control their residential networks by means of a management application. In this way, users can customize the allocation of resources (and set constraints, if desired) to connected devices in their residential network, fast and efficiently. This real-time customization enables new business models for network operators and service providers. As a proof of concept and to validate the management solution, we demonstrate, in a testbed environment, the operation of a dynamic network scenario where an operator has a business model in which users have a contracted basic bandwidth, but they are allowed to increase it temporarily when using highly demanding services.
Junta de Castilla y León (grant VA085G19)
Ministerio de Ciencia, Innovación y Universidades (grants (TEC2017-84423-C3-1-P and RED2018-102585-T)
Programa INTERREG V-A España-Portugal (grant 0677_DISRUPTIVE_2_E)
2021-08-24T09:50:34Z
2021-08-24T09:50:34Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.osn.2021.100631
Optical Switching and Networking, 2021, vol. 42, 100631
1573-4277
https://uvadoc.uva.es/handle/10324/48034
eng
https://www.sciencedirect.com/science/article/pii/S157342772100028X?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/481682021-08-29T18:31:23Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A clinically viable vendor-independent and device-agnostic solution for accelerated cardiac MRI reconstruction
Martín González, Elena
Moya Sáez, Elisa
Menchón Lara, Rosa María
Royuela del Val, Javier
Palencia de Lara, César
Rodríguez Cayetano, Manuel
Simmross Wattenberg, Federico Jesús
Alberola López, Carlos
Magnetic resonance imaging
Imagen por resonancia magnética
Graphics processing unit
Unidad de procesamiento gráfico
OpenCLIPER
Producción Científica
Background and objective: Recent research has reported methods that reconstruct cardiac MR images acquired with acceleration factors as high as 15 in Cartesian coordinates. However, the computational cost of these techniques is quite high, taking about 40 min of CPU time in a typical current machine. This delay between acquisition and final result can completely rule out the use of MRI in clinical environments in favor of other techniques, such as CT. In spite of this, reconstruction methods reported elsewhere can be parallelized to a high degree, a fact that makes them suitable for GPU-type computing devices. This paper contributes a vendor-independent, device-agnostic implementation of such a method to reconstruct 2D motion-compensated, compressed-sensing MRI sequences in clinically viable times. Methods: By leveraging our OpenCLIPER framework, the proposed system works in any computing device (CPU, GPU, DSP, FPGA, etc.), as long as an OpenCL implementation is available, and development is significantly simplified versus a pure OpenCL implementation. In OpenCLIPER, the problem is partitioned in independent black boxes which may be connected as needed, while device initialization and maintenance is handled automatically. Parallel implementations of both a groupwise FFD-based registration method, as well as a multicoil extension of the NESTA algorithm have been carried out as processes of OpenCLIPER. Our platform also includes significant development and debugging aids. HIP code and precompiled libraries can be integrated seamlessly as well since OpenCLIPER makes data objects shareable between OpenCL and HIP. This also opens an opportunity to include CUDA source code (via HIP) in prospective developments. Results: The proposed solution can reconstruct a whole 12–14 slice CINE volume acquired in 19–32 coils and 20 phases, with an acceleration factor of ranging 4–8, in a few seconds, with results comparable to another popular platform (BART). If motion compensation is included, reconstruction time is in the order of one minute. Conclusions: We have obtained clinically-viable times in GPUs from different vendors, with delays in some platforms that do not have correspondence with its price in the market. We also contribute a parallel groupwise registration subsystem for motion estimation/compensation and a parallel multicoil NESTA subsystem for -norm problem solving.
Ministerio de Economía, Industria y Competitividad (grant TEC2017-82408-R)
Asociación Española Contra el Cáncer (grant PRDVL19001MOYA)
2021-08-27T11:05:47Z
2021-08-27T11:05:47Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.cmpb.2021.106143
Computer Methods and Programs in Biomedicine, 2021, vol. 207, 106143
0169-2607
https://uvadoc.uva.es/handle/10324/48168
eng
https://www.sciencedirect.com/science/article/pii/S0169260721002182?via%3Dihub
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/484432021-09-19T18:32:35Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Estimation of nitrogen content in cucumber plant (Cucumis sativus L.) leaves using hyperspectral imaging data with neural network and partial least squares regressions
Sabzi, Sajad
Pourdarbani, Razieh
Rohban, Mohammad H.
García Mateos, Ginés
Arribas Sánchez, Juan Ignacio
Hyperspectral imaging
Imágenes hiperespectrales
Image processing
Procesamiento de imágenes
Nitrogen
Nitrógeno
Plants
Plantas
Producción Científica
In recent years, farmers have often mistakenly resorted to overuse of chemical fertilizers to increase crop yield. However, excessive consumption of fertilizers might lead to severe food poisoning. If nutritional deficiencies are detected early, it can help farmers to design better fertigation practices before the problem becomes unsolvable. The aim of this study is to predict the amount of nitrogen (N) content in cucumber (Cucumis sativus L., var. Super Arshiya-F1) plant leaves using hyperspectral imaging (HSI) techniques and three different regression methods: a hybrid artificial neural networks-particle swarm optimization (ANN-PSO); partial least squares regression (PLSR); and unidimensional deep learning convolutional neural networks (CNN). Cucumber plant seeds were planted in 20 different pots. After growing the plants, pots were categorized and three levels of nitrogen overdose were applied to each category: 30%, 60% and 90% excesses, called N30%, N60%, N90%, respectively. HSI images of plant leaves were captured before and after the application of nitrogen excess. A prediction regression model was developed for each individual category. Results showed that mean regression coefficients (R) for ANN-PSO were inside 0.937–0.965, PLSR 0.975–0.997, and CNN 0.965–0.985 ranges, test set. We conclude that regression models have a remarkable ability to accurately predict the amount of nitrogen content in cucumber plants from hyperspectral leaf images in a non-destructive way, being PLSR slightly ahead of CNN and ANN-PSO methods.
Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (grants RTI2018-098958-B-I00 and RTI2018-098156-B-C53)
2021-09-01T09:04:25Z
2021-09-01T09:04:25Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
https://doi.org/10.1016/j.chemolab.2021.104404
Chemometrics and Intelligent Laboratory Systems, 2021, vol. 217, 104404
0169-7439
https://uvadoc.uva.es/handle/10324/48443
eng
https://www.sciencedirect.com/science/article/pii/S0169743921001726?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/484502021-09-19T18:32:37Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A deep learning approach for synthetic MRI based on two routine sequences and training with synthetic data
Moya Sáez, Elisa
Peña Nogales, Óscar
Luis García, Rodrigo de
Alberola López, Carlos
Parametric Maps
Mapas paramétricos
Magnetic resonance imaging
Imagen por resonancia magnética
Producción Científica
Background and Objective: Synthetic magnetic resonance imaging (MRI) is a low cost procedure that serves as a bridge between qualitative and quantitative MRI. However, the proposed methods require very specific sequences or private protocols which have scarcely found integration in clinical scanners. We propose a learning-based approach to compute T1, T2, and PD parametric maps from only a pair of T1- and T2-weighted images customarily acquired in the clinical routine.
Methods: Our approach is based on a convolutional neural network (CNN) trained with synthetic data; specifically, a synthetic dataset with 120 volumes was constructed from the anatomical brain model of the BrainWeb tool and served as the training set. The CNN learns an end-to-end mapping function to transform the input T1- and T2-weighted images to their underlying T1, T2, and PD parametric maps. Then, conventional weighted images unseen by the network are analytically synthesized from the parametric maps. The network can be fine tuned with a small database of actual weighted images and maps for better performance.
Results:This approach is able to accurately compute parametric maps from synthetic brain data achieving normalized squared error values predominantly below 1%. It also yields realistic parametric maps from actual MR brain acquisitions with T1, T2, and PD values in the range of the literature and with correlation values above 0.95 compared to the T1 and T2 maps obtained from relaxometry sequences. Further, the synthesized weighted images are visually realistic; the mean square error values are always below 9% and the structural similarity index is usually above 0.90. Network fine tuning with actual maps improves performance, while training exclusively with a small database of actual maps shows a performance degradation.
Conclusions:These results show that our approach is able to provide realistic parametric maps and weighted images out of a CNN that (a) is trained with a synthetic dataset and (b) needs only two inputs, which are in turn obtained from a common full-brain acquisition that takes less than 8 minutes of scan time. Although a fine tuning with actual maps improves performance, synthetic data is crucial to reach acceptable performance levels. Hence, we show the utility of our approach for both quantitative MRI in clinical viable times and for the synthesis of additional weighted images to those actually acquired.
Ministerio de Ciencia, Innovación y Universidades (grants TEC2017-82408-R and RTI2018-094569-B-I00)
2021-09-01T10:05:03Z
2021-09-01T10:05:03Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
https://doi.org/10.1016/j.cmpb.2021.106371
Computer Methods and Programs in Biomedicine, 2021, vol. 210, 106371
0169-2607
https://uvadoc.uva.es/handle/10324/48450
eng
https://www.sciencedirect.com/science/article/pii/S0169260721004454?via%3Dihub
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/485852022-07-18T09:32:59Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Machine learning in medical emergencies: a systematic review and analysis
Robles Mendo, Inés
Marques, Gonçalo
Torre Díez, Isabel de la
López-Coronado Sánchez-Fortún, Miguel
Martín Rodríguez, Francisco
Machine learning
Health emergencies
Emergency medicine
Mobile applications
32 Ciencias Médicas
33 Ciencias Tecnológicas
Producción Científica
Despite the increasing demand for artifcial intelligence research in medicine, the functionalities of his methods in health emergency
remain unclear. Therefore, the authors have conducted this systematic review and a global overview study which aims to identify,
analyse, and evaluate the research available on diferent platforms, and its implementations in healthcare emergencies. The methodology
applied for the identifcation and selection of the scientifc studies and the diferent applications consist of two methods. On the one
hand, the PRISMA methodology was carried out in Google Scholar, IEEE Xplore, PubMed ScienceDirect, and Scopus. On the other
hand, a review of commercial applications found in the best-known commercial platforms (Android and iOS). A total of 20 studies
were included in this review. Most of the included studies were of clinical decisions (n=4, 20%) or medical services or emergency
services (n=4, 20%). Only 2 were focused on m-health (n=2, 10%). On the other hand, 12 apps were chosen for full testing on dif ferent devices. These apps dealt with pre-hospital medical care (n=3, 25%) or clinical decision support (n=3, 25%). In total, half
of these apps are based on machine learning based on natural language processing. Machine learning is increasingly applicable to
healthcare and ofers solutions to improve the efciency and quality of healthcare. With the emergence of mobile health devices and
applications that can use data and assess a patient's real-time health, machine learning is a growing trend in the healthcare industry.
Comisión Europea y Ministerio de Industria, Energía y Turismo (under project AAL-20125036 named BWetake Care: ICTbased)
2021-09-03T12:16:59Z
2021-09-03T12:16:59Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1007/s10916-021-01762-3
Journal of Medical Systems, 2021, vol. 45, n. 10
0148-5598
https://uvadoc.uva.es/handle/10324/48585
10
Journal of Medical Systems
45
1573-689X
eng
https://link.springer.com/article/10.1007/s10916-021-01762-3
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
application/pdf
Springer
oai:uvadoc.uva.es:10324/486772021-09-19T18:32:39Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Nondestructive estimation of three apple fruit properties at various ripening levels with optimal Vis-NIR spectral wavelength regression data
Pourdarbani, Razieh
Sabzi, Sajad
Arribas Sánchez, Juan Ignacio
Acidity
Acidez
Artificial neural networks
Redes neuronales artificiales
Physicochemical properties
Propiedades físico-químicas
Producción Científica
Nondestructive estimation of fruit properties during their ripening stages ensures the best value for producers and vendors. Among common quality measurement methods, spectroscopy is popular and enables physicochemical properties to be nondestructively estimated. The current study aims to nondestructively predict tissue firmness (kgf/cm), acidity (pH level) and starch content index (%) in apples (Malus M. pumila) samples (Fuji var.) at various ripening stages using visible/near infrared (Vis-NIR) spectral data in 400–1000 nm wavelength range. Results show that non-linear regression done by an artificial neural network-cultural algorithm (ANN-CA) was able to properly estimate the investigated fruit properties. Moreover, the performance of the proposed method was evaluated for Vis-NIR data based on optimal NIR wavelength values selected by a genetic optimization tool.
Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (project RTI2018-098958-B-I00)
2021-09-17T06:44:16Z
2021-09-17T06:44:16Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.heliyon.2021.e07942
Heliyon, 2021, vol. 7, n. 9, e07942
2405-8440
https://uvadoc.uva.es/handle/10324/48677
eng
https://www.sciencedirect.com/science/article/pii/S2405844021020454?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/486782022-01-25T21:47:19Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Optimization of acrylic-styrene latex-based biofilms as a platform for biological indoor air treatment
González Martín, Javier
Cantera Ruiz de Pellón, Sara
Lebrero Fernández, Raquel
Muñoz Torre, Raúl
Biofiltration
Biofiltración
Indoor air quality
Calidad del aire interior
Latex-based biofilms
Biofilms de latex
Producción Científica
Biotechnologies have emerged as a promising solution for indoor air purification with the potential to overcome the inherent limitations of indoor air treatment. These limitations include the low concentrations and variability of pollutants and mass-transfer problems caused by pollutant hydrophobicity. A new latex-based biocoating was herein optimized for the abatement of the volatile organic compounds (VOCs) toluene, trichloroethylene, n-hexane, and α-pinene using acclimated activated sludge dominated by members of the phylum Patescibacteria. The influence of the water content, the presence of water absorbing compounds, the latex pretreatment, the biomass concentration, and the pollutant load was tested on VOC removal efficiency (RE) by varying the formulation of the mixtures. Overall, hexane and trichloroethylene removal was low (<30%), while high REs (>90%) were consistently recorded for toluene and pinene. The assays demonstrated the benefits of operating at high water content in the biocoating, either by including mineral medium or water absorbing compounds in the latex-biomass mixtures. The performance of the latex-based biocoating was likely limited by VOC mass-transfer rather than by biomass concentration in the biocoating. The latex-based biocoating supported a superior toluene and pinene removal than biomass in suspension when VOC loading rate was increased by a factor of 4.
Ministerio de Ciencia, Innovación y Universidades (project RTI2018-0-096441-B-I00]
Junta de Castilla y León (grant CLU 2017-09)
2021-09-17T07:12:41Z
2021-09-17T07:12:41Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.chemosphere.2021.132182
Chemosphere, 2021, vol. 287, n. 3, 132182
0045-6535
https://uvadoc.uva.es/handle/10324/48678
eng
https://www.sciencedirect.com/science/article/pii/S0045653521026540?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/488482021-09-29T20:59:00Zcom_10324_48853com_10324_954com_10324_894com_10324_1191com_10324_931col_10324_48854col_10324_1379
An experimental openflow proposal over legacy GPONs to allow real-time service reconfiguration policies
Merayo Álvarez, Noemí
Pintos, David de
Aguado Manzano, Juan Carlos
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Software defined networking
Redes definidas por software
GPONs
Reconfiguration policies
Políticas de reconfiguración
Experimental validation
Validación experimental
Producción Científica
The integration of Software Defined Networking (SDN) technologies in Passive Optical Networks (PONs) would provide great advantages to Internet Service Providers (ISPs) and Network Operators, since they can optimize the network operation and reduce its complexity. However, some tasks regarding online service and network configuration strategies are difficult to move to external SDN-controllers since they are time-critical operations. However, the control of some of these policies by SDN techniques could lead to better network and management configuration in a centralized and automatic way. As a consequence, we propose and experimentally test the integration of an OpenFlow approach over legacy Gigabit Passive Optical Networks (GPONs), which allows moving some global service configuration policies to an external SDN controller implementing an SDN management layer that adjust these strategies according to dynamic Quality of Service (QoS) requirements of services in residential users. The viability and efficiency of our approach are demonstrated using a GPON testbed and proposing a new business scenario for ISPs and Network Operators.
Ministerio de Ciencia, Innovación y Universidades (projects TEC2017-84423-C3-1-P and RTC2019-007043-7)
Junta de Castilla y León (project VA085G19)
Unión Europea a través del programa INTERREG V-A España-Portugal (project 0677_DISRUPTIVE_2_E)
2021-09-29T12:31:29Z
2021-09-29T12:31:29Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/app11030903
Applied Sciences, 2021, vol. 11, n. 3, 903
2076-3417
https://uvadoc.uva.es/handle/10324/48848
eng
https://www.mdpi.com/2076-3417/11/3/903
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 MDPI
application/pdf
MDPI
oai:uvadoc.uva.es:10324/488522022-04-25T07:33:07Zcom_10324_48853com_10324_954com_10324_894com_10324_1191com_10324_931col_10324_48854col_10324_1379
A testbed and a simulation laboratory for training engineering students in optical access network technologies
Merayo Álvarez, Noemí
Aguado Manzano, Juan Carlos
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Engineering curriculum
Ingeniería - Programas de estudios
Experimental learning
Aprendizaje experimental
Laboratory
Laboratorio
Optical communications
Comunicación óptica
Producción Científica
Engineering profiles focused on next-generation optical networks are gaining immense importance due to new emerging services and the amount of data expected in future network scenarios. In fact, not only are optical access networks leading to a major revolution in the network industry, but passive optical networks are the most widely deployed access networks worldwide today. This should be a strong incentive for universities to train their students in these innovative and recent technologies. In this vein, we propose the deployment of an optical communication laboratory with on-site experimental sessions in which students work with commercial equipment and realistic working environments. These working environments are necessary to train professionals in the area of optical networks. However, due to the high cost of the optical communications equipment, it is not possible to have a working place for each group and we combine these experimental sessions with some simulation sessions to complete the training. We present the design of this lab and a qualitative and quantitative study aimed at analyzing students’ experiences, the skills they have acquired, and the potential impact on their future careers. This study shows that students have a very positive perception of the lab, emphasizing that working with real equipment helps them improve technical skills and assimilate theoretical knowledge. They also point out they would like a higher number of subjects in their degrees to employ this type of lab. Finally, students perceive these sessions as very useful for their professional future.
Unión Europea a través del programa INTERREG V-A España-Portugal (project 0677_DISRUPTIVE_2_E)
Junta de Castilla y León (grant VA085G19)
Ministerio de Ciencia, Innovación y Universidades (grants TEC2017-84423-C3-1-P and RED2018-102585-T)
2021-09-29T12:56:22Z
2021-09-29T12:56:22Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1002/cae.22429
Computer Applications in Engineering Education, 2021, vol. 29, n. 6. p. 1892-1910
1099-0542
https://uvadoc.uva.es/handle/10324/48852
eng
https://onlinelibrary.wiley.com/doi/10.1002/cae.22429
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 Wiley
application/pdf
Wiley
oai:uvadoc.uva.es:10324/489722022-01-25T21:47:24Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Supervised contrastive learning over prototype-label embeddings for network intrusion detection
López Martín, Manuel
Sánchez Esguevillas, Antonio Javier
Arribas Sánchez, Juan Ignacio
Carro Martínez, Belén
Label embedding
Incrustación de etiquetas
Contrastive learning
Aprendizaje contrastivo
Network intrusion detection
Detección de intrusos en red
Producción Científica
Contrastive learning makes it possible to establish similarities between samples by comparing their distances in an intermediate representation space (embedding space) and using loss functions designed to attract/repel similar/dissimilar samples. The distance comparison is based exclusively on the sample features. We propose a novel contrastive learning scheme by including the labels in the same embedding space as the features and performing the distance comparison between features and labels in this shared embedding space. Following this idea, the sample features should be close to its ground-truth (positive) label and away from the other labels (negative labels). This scheme allows to implement a supervised classification based on contrastive learning. Each embedded label will assume the role of a class prototype in embedding space, with sample features that share the label gathering around it. The aim is to separate the label prototypes while minimizing the distance between each prototype and its same-class samples. A novel set of loss functions is proposed with this objective. Loss minimization will drive the allocation of sample features and labels in embedding space. Loss functions and their associated training and prediction architectures are analyzed in detail, along with different strategies for label separation. The proposed scheme drastically reduces the number of pair-wise comparisons, thus improving model performance. In order to further reduce the number of pair-wise comparisons, this initial scheme is extended by replacing the set of negative labels by its best single representative: either the negative label nearest to the sample features or the centroid of the cluster of negative labels. This idea creates a new subset of models which are analyzed in detail.
The outputs of the proposed models are the distances (in embedding space) between each sample and the label prototypes. These distances can be used to perform classification (minimum distance label), features dimensionality reduction (using the distances and the embeddings instead of the original features) and data visualization (with 2 or 3D embeddings).
Although the proposed models are generic, their application and performance evaluation is done here for network intrusion detection, characterized by noisy and unbalanced labels and a challenging classification of the various types of attacks. Empirical results of the model applied to intrusion detection are presented in detail for two well-known intrusion detection datasets, and a thorough set of classification and clustering performance evaluation metrics are included.
Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación - Fondo Europeo de Desarrollo Regional (grant RTI2018-098958-B-I00)
2021-10-08T11:54:48Z
2021-10-08T11:54:48Z
2022
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.inffus.2021.09.014
Information Fusion, 2022, vol. 79, p. 200-228
1566-2535
https://uvadoc.uva.es/handle/10324/48972
eng
https://www.sciencedirect.com/science/article/pii/S1566253521001913?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/490502021-11-23T13:35:31Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Optimal approximation to unitary quantum operators with linear optics
García Escartín, Juan Carlos
Gimeno, Vicent
Moyano Fernández, Julio José
Optical implementations of quantum evolutions
Quantum optics
Toponogov’s Theorem
33 Ciencias Tecnológicas
12 Matemáticas
22 Física
Producción Científica
Linear optical systems acting on photon number states produce many interesting evolutions, but cannot give all the allowed quantum operations on the input state. Using
Toponogov’s theorem from differential geometry, we propose an iterative method
that, for any arbitrary quantum operator U acting on n photons in m modes, returns an
operator Ũ which can be implemented with linear optics. The approximation method
is locally optimal and converges. The resulting operator Ũ can be translated into an
experimental optical setup using previous results.
Ministerio de Ciencia e Innovación- FEDER (grants PID2020-119418GB-I00 and PID2020-115930GA-I00)
Junta de Castilla y León (project VA296P18)
Universitat Jaume I (project UJI-B2018- 35 and grant UJI-B2018-10)
Ministerio de Asuntos Económicos y Transformación Digital (grant MTM2017-84851-C2-2)
Ministerios de Ciencia e Innovación y de Universidades (grant PGC2018-096446-B-C22)
2021-10-13T11:59:46Z
2021-10-13T11:59:46Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1007/s11128-021-03254-2
Quantum Information Processing, 2021, vol. 20, n. 9, n art. 314, p. 1-18
1570-0755
https://uvadoc.uva.es/handle/10324/49050
9
Quantum Information Processing
20
1573-1332
eng
https://www.springerprofessional.de/en/optimal-approximation-to-unitary-quantum-operators-with-linear-o/19685008
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 The Authors
application/pdf
Springer
oai:uvadoc.uva.es:10324/497622021-12-05T19:30:52Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Solar light-driven reduction of crystal violet by a composite of g-C3N4, β-Ag2Se, γ-Fe2O3 and graphite
Dante, Roberto C.
Martín Ramos, Pablo
Chamorro Posada, Pedro
Rutto, Dario
Vázquez Cabo, José
Dante, Denisse G.
Barberis, Riccardo
Rubiños López, Óscar
In this work, a new g-C3N4-based Z-scheme with γ-Fe2O3 and β-Ag2Se both n-type semiconductors, and graphite to favor electron exchange is presented. The composite material was studied by XRD, FTIR, UV-Vis, TEM, XPS, TGA, DSC and TOF-SIMS, and the ability of this photocatalytic system to act as a photo-reductant was assessed using crystal violet (CV+) dye. Solar light driven photo-reduction of CV+ in the presence of tri-sodium citrate evidenced a synergistic enhancement of the activity of the composite toward reduction, with ∼20 times higher conversion rates per unit of surface area than those of g-C3N4. Photo-oxidation experiments under Xe lamp irradiation in the presence of H2O2 also showed that the AgFeCN composite featured a higher activity (∼8×) than g-C3N4. This Z-scheme may deserve further study as a photo-reductant to obtain hydrogen or hydrogenated compounds. Moreover, the use of CV+ may represent a facile procedure that can aid in the selection of new photocatalysts to be used in hydrogen production.
2021-11-06T18:15:13Z
2021-11-06T18:15:13Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
https://doi.org/10.1080/1536383X.2020.1713762
Fullerenes, Nanotubes and Carbon Nanostructures, 2020, vol. 28 , p. 533-540.
1536-383X
https://uvadoc.uva.es/handle/10324/49762
533
7
540
Fullerenes, Nanotubes and Carbon Nanostructures
28
1536-4046
spa
https://www.tandfonline.com/doi/abs/10.1080/1536383X.2020.1713762?journalCode=lfnn20
info:eu-repo/semantics/openAccess
application/pdf
Taylor & Francis
oai:uvadoc.uva.es:10324/509482022-01-25T21:47:28Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Brain-computer interface channel selection optimization using meta-heuristics and evolutionary algorithms
Martínez Cagigal, Víctor
Santamaría Vázquez, Eduardo
Hornero Sánchez, Roberto
Brain-computer interfaces
Interfaces cerebro-computadora
Evolutionary algorithms
Algoritmos evolutivos
Producción Científica
Many brain–computer interface (BCI) studies overlook the channel optimization due to its inherent complexity. However, a careful channel selection increases the performance and users’ comfort while reducing the cost of the system. Evolutionary meta-heuristics, which have demonstrated their usefulness in solving complex problems, have not been fully exploited yet in this context. The purpose of the study is two-fold: (1) to propose a novel algorithm to find an optimal channel set for each user and compare it with other existing meta-heuristics; and (2) to establish guidelines for adapting these optimization strategies to this framework. A total of 3 single-objective (GA, BDE, BPSO) and 4 multi-objective (NSGA-II, BMOPSO, SPEA2, PEAIL) existing algorithms have been adapted and tested with 3 public databases: ‘BCI competition III–dataset II’, ‘Center Speller’ and ‘RSVP Speller’. Dual-Front Sorting Algorithm (DFGA), a novel multi-objective discrete method especially designed to the BCI framework, is proposed as well. Results showed that all meta-heuristics outperformed the full set and the common 8-channel set for P300-based BCIs. DFGA showed a significant improvement of accuracy of 3.9% over the latter using also 8 channels; and obtained similar accuracies using a mean of 4.66 channels. A topographic analysis also reinforced the need to customize a channel set for each user. Thus, the proposed method computes an optimal set of solutions with different number of channels, allowing the user to select the most appropriate distribution for the next BCI sessions.
Ministerio de Ciencia, Innovación y Universidades (project RTC2019-007350-1)
Comisión Europea (project 0702_MIGRAINEE_2_E)
2021-12-15T09:10:03Z
2021-12-15T09:10:03Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.asoc.2021.108176
Applied Soft Computing, 2021, vol. 115, 108176
1568-4946
https://uvadoc.uva.es/handle/10324/50948
eng
https://www.sciencedirect.com/science/article/pii/S1568494621010292?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/517782022-01-31T21:46:42Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Robust asynchronous control of ERP-Based brain-Computer interfaces using deep learning
Santamaría Vázquez, Eduardo
Martínez Cagigal, Víctor
Pérez Velasco, Sergio
Marcos Martínez, Diego
Hornero Sánchez, Roberto
Brain-computer interfaces
Interfaces cerebro-computadora
Deep learning
Aprendizaje inteligente
Producción Científica
Background and Objective. Brain-computer interfaces (BCI) based on event-related potentials (ERP) are a promising technology for alternative and augmented communication in an assistive context. However, most approaches to date are synchronous, requiring the intervention of a supervisor when the user wishes to turn his attention away from the BCI system. In order to bring these BCIs into real-life applications, a robust asynchronous control of the system is required through monitoring of user attention. Despite the great importance of this limitation, which prevents the deployment of these systems outside the laboratory, it is often overlooked in research articles. This study was aimed to propose a novel method to solve this problem, taking advantage of deep learning for the first time in this context to overcome the limitations of previous strategies based on hand-crafted features. Methods. The proposed method, based on EEG-Inception, a novel deep convolutional neural network, divides the problem in 2 stages to achieve the asynchronous control: (i) the model detects user’s control state, and (ii) decodes the command only if the user is attending to the stimuli. Additionally, we used transfer learning to reduce the calibration time, even exploring a calibration-less approach. Results. Our method was evaluated with 22 healthy subjects, analyzing the impact of the calibration time and number of stimulation sequences on the system’s performance. For the control state detection stage, we report average accuracies above 91% using only 1 sequence of stimulation and 30 calibration trials, reaching a maximum of 96.95% with 15 sequences. Moreover, our calibration-less approach also achieved suitable results, with a maximum accuracy of 89.36%, showing the benefits of transfer learning. As for the overall asynchronous system, which includes both stages, the maximum information transfer rate was 35.54 bpm, a suitable value for high-speed communication. Conclusions. The proposed strategy achieved higher performance with less calibration trials and stimulation sequences than former approaches, representing a promising step forward that paves the way for more practical applications of ERP-based spellers.
Ministerio de Ciencia, Innovación y Universidades - Agencia Estatal de Investigación (grants PID2020-115468RB-I00 and RTC2019-007350-1)
Comisión Europea - Fondo Europeo de Desarrollo Regional (cooperation programme Interreg V-A Spain-Portugal POCTEP 2014–2020)
2022-01-31T09:36:58Z
2022-01-31T09:36:58Z
2022
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.cmpb.2022.106623
Computer Methods and Programs in Biomedicine, 2022, vol. 215, 106623
0169-2607
https://uvadoc.uva.es/handle/10324/51778
eng
https://www.sciencedirect.com/science/article/pii/S0169260722000086?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/517792022-01-31T21:46:45Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Moment-based representation of the diffusion inside the brain from reduced DMRI acquisitions: Generalized AMURA
Aja Fernández, Santiago
Pieciak, Tomasz
Martín Martín, Carmen
Planchuelo Gómez, Álvaro
Luis García, Rodrigo de
Tristán Vega, Antonio
Diffusion MRI
Difusión MRI
Anisotropic diffusion
Difusión anisotrópica
Producción Científica
AMURA (Apparent Measures Using Reduced Acquisitions) was originally proposed as a method to infer micro-structural information from single-shell acquisitions in diffusion MRI. It reduces the number of samples needed and the computational complexity of the estimation of diffusion properties of tissues by assuming the diffusion anisotropy is roughly independent on the b-value. This simplification allows the computation of simplified expressions and makes it compatible with standard acquisition protocols commonly used even in clinical practice. The present work proposes an extension of AMURA that allows the calculation of general moments of the diffusion signals that can be applied to describe the diffusion process with higher accuracy. We provide simplified expressions to analytically compute a set of scalar indices as moments of arbitrary orders over either the whole 3-D space, particular directions, or particular planes. The existing metrics previously proposed for AMURA (RTOP, RTPP and RTAP) are now special cases of this generalization. An extensive set of experiments is performed on public data and a clinical clase acquired with a standard type acquisition. The new metrics provide additional information about the diffusion processes inside the brain.
Ministerio de Ciencia, Innovación y Universidades (grant RTI2018-094569-B-I00)
Polish National Agency for Academic Exchange (grant PN/BEK/2019/1/00421)
Ministry of Science and Higher Education of Poland (scholarship 692/STYP/13/2018)
Junta de Castilla y León - Fondo Social Europeo (ID: 376062)
2022-01-31T09:57:02Z
2022-01-31T09:57:02Z
2022
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.media.2022.102356
Medical Image Analysis, 2022, vol. 77, 102356
1361-8415
https://uvadoc.uva.es/handle/10324/51779
eng
https://www.sciencedirect.com/science/article/pii/S1361841522000093?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/521062022-09-30T10:48:03Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Anisotropy measure from three diffusion-encoding gradient directions
Aja Fernández, Santiago
París l Bandrés, Guillem Lluis
Martín Martín, Carmen
Jones, Derek K.
Tristán Vega, Antonio
Anisotropy
Anisotropía
Brain
Cerebro
Producción Científica
We propose a method that can provide information about the anisotropy and orientation of diffusion in the brain from only 3 orthogonal gradient directions without imposing additional assumptions. The method is based on the Diffusion Anisotropy (DiA) that measures the distance from a diffusion signal to its isotropic equivalent. The original formulation based on a Spherical Harmonics basis allows to go down to only 3 orthogonal directions in order to estimate the measure. In addition, an alternative simplification and a color-coding representation are also proposed. Acquisitions from a publicly available database are used to test the viability of the proposal. The DiA succeeded in providing anisotropy information from the white matter using only 3 diffusion-encoding directions. The price to pay for such reduced acquisition is an increment in the variability of the data and a subestimation of the metric on those tracts not aligned with the acquired directions. Nevertheless, the calculation of anisotropy information from DMRI is feasible using fewer than 6 gradient directions by using DiA. The method is totally compatible with existing acquisition protocols, and it may provide complementary information about orientation in fast diffusion acquisitions.
Ministerio de Ciencia e Innovación (grant RTI2018-094569-B-I00)
Wellcome Trust Investigator Award (award 096646/Z/11/Z)
Wellcome Trust Strategic Award (award 104943/Z/14/Z)
2022-02-21T09:17:23Z
2022-02-21T09:17:23Z
2022
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.mri.2022.01.014
Magnetic Resonance Imaging, 2022, vol. 88. p. 38-43
0730-725X
https://uvadoc.uva.es/handle/10324/52106
eng
https://www.sciencedirect.com/science/article/pii/S0730725X22000145?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/523182022-03-09T21:49:47Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Weed Classification for Site-Specific Weed Management Using an Automated Stereo Computer-Vision Machine-Learning System in Rice Fields
Dadashzadeh, Mojtaba
Abbaspour Gilandeh, Yousef
Mesri Gundoshmian, Tarahom
Sabzi, Sajad
Hernández Hernández, José Luis
Hernández Hernández, Mario
Arribas Sánchez, Juan Ignacio
Sustainable agriculture
Agricultura sostenible
Eco-friendly techniques
Técnicas ecológicas
Producción Científica
Site-specific weed management and selective application of herbicides as eco-friendly techniques are still challenging tasks to perform, especially for densely cultivated crops, such as rice. This study is aimed at developing a stereo vision system for distinguishing between rice plants and weeds and further discriminating two types of weeds in a rice field by using artificial neural networks (ANNs) and two metaheuristic algorithms. For this purpose, stereo videos were recorded across the rice field and different channels were extracted and decomposed into the constituent frames. Next, upon pre-processing and segmentation of the frames, green plants were extracted out of the background. For accurate discrimination of the rice and weeds, a total of 302 color, shape, and texture features were identified. Two metaheuristic algorithms, namely particle swarm optimization (PSO) and the bee algorithm (BA), were used to optimize the neural network for selecting the most effective features and classifying different types of weeds, respectively. Comparing the proposed classification method with the K-nearest neighbors (KNN) classifier, it was found that the proposed ANN-BA classifier reached accuracies of 88.74% and 87.96% for right and left channels, respectively, over the test set. Taking into account either the arithmetic or the geometric means as the basis, the accuracies were increased up to 92.02% and 90.7%, respectively, over the test set. On the other hand, the KNN suffered from more cases of misclassification, as compared to the proposed ANN-BA classifier, generating an overall accuracy of 76.62% and 85.59% for the classification of the right and left channel data, respectively, and 85.84% and 84.07% for the arithmetic and geometric mean values, respectively.
2022-03-09T09:05:33Z
2022-03-09T09:05:33Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/plants9050559
Plants, 2020, vol. 9, n. 5, 559
2223-7747
https://uvadoc.uva.es/handle/10324/52318
eng
https://www.mdpi.com/2223-7747/9/5/559/htm
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2020 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/523642022-07-18T09:32:59Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Myoelectric gaming in the rehabilitation of patients with C7 spinal cord injury
Rosa Steinz, Ramón de la
Carrera, Albano
Alonso Alonso, Alonso
Peñasco Martín, Benito
Gil Agudo, Angel
Abril Domingo, Evaristo José
Spinal cord injury
Rehabilitation
Electromyography
Myoelectric control
Biofeedback
33 Ciencias Tecnológicas
32 Ciencias Médicas
Producción Científica
This paper analyses the role of myoelectric games in the rehabilitation of paraplegic patients. The University of Valladolid neuromuscular training system, UVa-NTS platform, which allows the myoelectric command of computer applications, has been introduced in rehabilitation sessions of a group of paraplegic patients. The experiments took place both at the University of Valladolid and at the National Hospital for Paraplegics of Toledo in Spain. A homogeneous population of five patients with a C7 spinal cord injury was compared with a group of control subjects. The myoelectric control was performed with the flexor carpi radialis and the extensor carpi radialis muscles. The myoelectric routines were timed and the game scores measured. Notwithstanding the reduced mobility of the patients, they achieved fast adaptation and better timings than the control subjects in the first experiment (p < 0.001), although this difference was reduced in further experiments. Both patients and control subjects played satisfactorily with the Myo-Pong game. However, the improvement in the scores was better for the control subjects between sessions (p = 0.009) when compared with the patients (p = 0.978). The results show that patients and control subjects were able to perform and reached similar scores. However, patients’ improvement in further rehabilitation sessions was lesser than when compared with the control subjects.
2022-03-10T09:11:38Z
2022-03-10T09:11:38Z
2019
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/app9091912
Applied Sciences, 2019, vol. 9, n. 9, p.1912.
2076-3417
https://uvadoc.uva.es/handle/10324/52364
1912
9
Applied Sciences
9
2076-3417
eng
https://www.mdpi.com/2076-3417/9/9/1912
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2019 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/524502022-03-15T21:47:37Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
MAFC: Multi-Agent Fog Computing Model for Healthcare Critical Tasks Management
Awad Mutlag, Ammar
Abd Ghani, Mohd Khanapi
Mohammed, Mazin Abed
Maashi, Mashael S.
Mohd, Othman
Mostafa, Salama
Abdulkareem, Karrar Hameed
Marques, Gonçalo
Torre Díez, Isabel de la
Fog computing
Computación en niebla
Producción Científica
In healthcare applications, numerous sensors and devices produce massive amounts of data which are the focus of critical tasks. Their management at the edge of the network can be done by Fog computing implementation. However, Fog Nodes suffer from lake of resources That could limit the time needed for final outcome/analytics. Fog Nodes could perform just a small number of tasks. A difficult decision concerns which tasks will perform locally by Fog Nodes. Each node should select such tasks carefully based on the current contextual information, for example, tasks’ priority, resource load, and resource availability. We suggest in this paper a Multi-Agent Fog Computing model for healthcare critical tasks management. The main role of the multi-agent system is mapping between three decision tables to optimize scheduling the critical tasks by assigning tasks with their priority, load in the network, and network resource availability. The first step is to decide whether a critical task can be processed locally; otherwise, the second step involves the sophisticated selection of the most suitable neighbor Fog Node to allocate it. If no Fog Node is capable of processing the task throughout the network, it is then sent to the Cloud facing the highest latency. We test the proposed scheme thoroughly, demonstrating its applicability and optimality at the edge of the network using iFogSim simulator and UTeM clinic data.
2022-03-15T09:36:13Z
2022-03-15T09:36:13Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/s20071853
Sensors, 2020, vol. 20, n. 7, 1853
1424-8220
https://uvadoc.uva.es/handle/10324/52450
eng
https://www.mdpi.com/1424-8220/20/7/1853
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/525132022-04-19T20:48:06Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
From urea to melamine cyanurate: Study of a class of thermal condensation routes for the preparation of graphitic carbon nitride
Chamorro Posada, Pedro
Dante, Roberto C.
Vázquez Cabo, José
Dante, Denisse G.
Martín Ramos, Pablo
Rubiños López, Óscar
Sánchez Arévalo, Francisco M.
Carbon nitride
Nitruro de carbono
Luminescence properties
Propiedades luminiscentes
Melamine cyanurate
Cianurato de melamina
Producción Científica
This work presents a survey of the intermediates in the well-known thermal synthesis of graphitic carbon nitride from urea. The analysis of the crystalline phases depicts a successive transformation of the precursor into different substances previously used as starting reactants, whereby melamine cyanurate arises as the ultimate precursor of a class of thermal condensation routes to obtain graphitic carbon nitride. The study of the optical properties of the synthesized materials evidences the simultaneous production of an amorphous phase with a significant presence of melon oligomers. These results are also supported by the further characterization of the materials performed using THz-TDS, FT-IR, HRTEM, and XPS techniques, and by theoretical studies conducted using semi-empirical quantum chemistry methods.
Junta de Castilla y León (grant VA296P18)
Ministerio de Ciencia, Innovación y Universidades (grant PID2020-320 119418GB-I00)
2022-03-16T13:06:58Z
2022-03-16T13:06:58Z
2022
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.jssc.2022.123071
Journal of Solid State Chemistry, 2022, vol. 310, 123071
0022-4596
https://uvadoc.uva.es/handle/10324/52513
eng
https://www.sciencedirect.com/science/article/pii/S0022459622001955?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2022 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/525292022-07-18T09:33:00Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A systematic review of mHealth apps evaluations for cardiac issues
Villarreal, Vladimir
Castillo Sánchez, Gema Anabel
Hamrioui, Sofiane
Berbey Álvarez, Aránzazu
Torre Díez, Isabel de la
Lorenz, Pascal
Hypertension solution
Cardiac applications
Heart rate monitoring
Mobile health development
Wearables technologies
33 Ciencias Tecnológicas
32 Ciencias Médicas
Producción Científica
Currently, with the widespread penetration of mobile devices with Internet access, including the smartphones, they can allow specific and/or complementary activities in the health field as well as in other commercial sectors. To verify the impact of the studies about medical scientific publications relatives to cardiac mobile applications (app). This review corresponds to information in scientific journals of high impact. The intention of this review is respond to the follow question: How these research works have evaluated the performance of health mobile applications, with a special interest in cardiac issues? This review of these searches corresponds to an analysis by 4 categories, which are: Assessment of the wearables—Body Care, Use of sensors in the applications, app in health, Health Care—Comparisons of review app and app specialized commercial/clinical use. Only 6% of the app are associated with a medical professional, 15% is published by a professional medical society and 63% according to the opinions of the user. It provides evidence of how some apps have been evaluated, and in some cases the effectiveness of the estimated accuracy is not in line with the real situation. In Panama, a platform has been presented that permit the integration of health applications for patient follow-up. AmI-HEALTH has been developed to provide a mechanism for self-management of hypertensive patient data, by re-cording elements such as blood pressure (systolic, diastolic and pulse). In this point is very important to remember to the near relation between the Cardiac Issues and the hypertension condition. This makes us reflect on the true implications that bring us closer to these technological innovations. Today, our world is so changing and globalized.
Secretaría Nacional de Ciencia, Tecnología e Innovación (SENACYT) and development by Technological University of Panama (Project ITE15-001)
2022-03-17T09:01:38Z
2022-03-17T09:01:38Z
2018
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/proceedings2190481
Proceedings, 2018, vol. 2, n. 19, p. 481
2504-3900
https://uvadoc.uva.es/handle/10324/52529
481
19
Proceedings
2
eng
https://www.mdpi.com/2504-3900/2/19/481
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2018 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/526032022-03-23T21:53:27Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Internet of things and enhanced living environments: measuring and mapping air quality using cyber-physical systems and mobile computing technologies
Marques, Gonçalo
Miranda, Nuno
Bhoi, Akash Kumar
Garcia Zapirain, Begonya
Hamrioui, Sofiane
Torre Díez, Isabel de la
Air quality
Aire - Calidad
Mobile computing
Computación móvil
Producción Científica
This paper presents a real-time air quality monitoring system based on Internet of Things. Air quality is particularly relevant for enhanced living environments and well-being. The Environmental Protection Agency and the World Health Organization have acknowledged the material impact of air quality on public health and defined standards and policies to regulate and improve air quality. However, there is a significant need for cost-effective methods to monitor and control air quality which provide modularity, scalability, portability, easy installation and configuration features, and mobile computing technologies integration. The proposed method allows the measuring and mapping of air quality levels considering the spatial-temporal information. This system incorporates a cyber-physical system for data collection and mobile computing software for data consulting. Moreover, this method provides a cost-effective and efficient solution for air quality supervision and can be installed in vehicles to monitor air quality while travelling. The results obtained confirm the implementation of the system and present a relevant contribution to enhanced living environments in smart cities. This supervision solution provides real-time identification of unhealthy behaviours and supports the planning of possible interventions to increase air quality.
Ministerio de Industria, Energía y Turismo - Unión Europea (project AAL-20125036)
2022-03-23T10:31:46Z
2022-03-23T10:31:46Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/s20030720
Sensors, 2020, vol. 20, n. 3, 720
1424-8220
https://uvadoc.uva.es/handle/10324/52603
eng
https://www.mdpi.com/1424-8220/20/3/720
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/526202022-03-24T21:47:52Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A computer vision system for the automatic classification of five varieties of tree leaf images
Sabzi, Sajad
Pourdarbani, Razieh
Arribas Sánchez, Juan Ignacio
Computer vision
Visión artificial
Neural networks
Redes neuronales
Precision agriculture
Agricultura de precisión
Producción Científica
A computer vision system for automatic recognition and classification of five varieties of plant leaves under controlled laboratory imaging conditions, comprising: 1–Cydonia oblonga (quince), 2–Eucalyptus camaldulensis dehn (river red gum), 3–Malus pumila (apple), 4–Pistacia atlantica (mt. Atlas mastic tree) and 5–Prunus armeniaca (apricot), is proposed. 516 tree leaves images were taken and 285 features computed from each object including shape features, color features, texture features based on the gray level co-occurrence matrix, texture descriptors based on histogram and moment invariants. Seven discriminant features were selected and input for classification purposes using three classifiers: hybrid artificial neural network–ant bee colony (ANN–ABC), hybrid artificial neural network–biogeography based optimization (ANN–BBO) and Fisher linear discriminant analysis (LDA). Mean correct classification rates (CCR), resulted in 94.04%, 89.23%, and 93.99%, for hybrid ANN–ABC; hybrid ANN–BBO; and LDA classifiers, respectively. Best classifier mean area under curve (AUC), mean sensitivity, and mean specificity, were computed for the five tree varieties under study, resulting in: 1–Cydonia oblonga (quince) 0.991 (ANN–ABC), 95.89% (ANN–ABC), 95.91% (ANN–ABC); 2–Eucalyptus camaldulensis dehn (river red gum) 1.00 (LDA), 100% (LDA), 100% (LDA); 3–Malus pumila (apple) 0.996 (LDA), 96.63% (LDA), 94.99% (LDA); 4–Pistacia atlantica (mt. Atlas mastic tree) 0.979 (LDA), 91.71% (LDA), 82.57% (LDA); and 5–Prunus armeniaca (apricot) 0.994 (LDA), 88.67% (LDA), 94.65% (LDA), respectively.
Unión Europea (project 585596-EPP-1-2017-1-DE-EPPKA2-CBHE-JP)
2022-03-24T09:09:31Z
2022-03-24T09:09:31Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/computers9010006
Computers, 2020, vol. 9, n. 1, 6
2073-431X
https://uvadoc.uva.es/handle/10324/52620
eng
https://www.mdpi.com/2073-431X/9/1/6
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/526282022-03-24T21:47:55Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
A computer vision system based on majority-voting ensemble neural network for the automatic classification of three chickpea varieties
Pourdarbani, Razieh
Sabzi, Sajad
Kalantari, Davood
Hernández Hernández, José Luis
Arribas Sánchez, Juan Ignacio
Chickpeas
Garbanzos
Computer vision
Visión artificial
Image processing
Procesamiento de imágenes
Producción Científica
Since different varieties of crops have specific applications, it is therefore important to properly identify each cultivar, in order to avoid fake varieties being sold as genuine, i.e., fraud. Despite that properly trained human experts might accurately identify and classify crop varieties, computer vision systems are needed since conditions such as fatigue, reproducibility, and so on, can influence the expert’s judgment and assessment. Chickpea (Cicer arietinum L.) is an important legume at the world-level and has several varieties. Three chickpea varieties with a rather similar visual appearance were studied here: Adel, Arman, and Azad chickpeas. The purpose of this paper is to present a computer vision system for the automatic classification of those chickpea varieties. First, segmentation was performed using an Hue Saturation Intensity (HSI) color space threshold. Next, color and textural (from the gray level co-occurrence matrix, GLCM) properties (features) were extracted from the chickpea sample images. Then, using the hybrid artificial neural network-cultural algorithm (ANN-CA), the sub-optimal combination of the five most effective properties (mean of the RGB color space components, mean of the HSI color space components, entropy of GLCM matrix at 90°, standard deviation of GLCM matrix at 0°, and mean third component in YCbCr color space) were selected as discriminant features. Finally, an ANN-PSO/ACO/HS majority voting (MV) ensemble methodology merging three different classifier outputs, namely the hybrid artificial neural network-particle swarm optimization (ANN-PSO), hybrid artificial neural network-ant colony optimization (ANN-ACO), and hybrid artificial neural network-harmonic search (ANN-HS), was used. Results showed that the ensemble ANN-PSO/ACO/HS-MV classifier approach reached an average classification accuracy of 99.10 ± 0.75% over the test set, after averaging 1000 random iterations.
Unión Europea (project 585596-EPP-1-2017-1-DE-EPPKA2-CBHE-JP)
2022-03-24T10:17:52Z
2022-03-24T10:17:52Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.3390/foods9020113
Foods, 2020, vol. 9, n. 2, 113
2304-8158
https://uvadoc.uva.es/handle/10324/52628
eng
https://www.mdpi.com/2304-8158/9/2/113
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2020 The Authors
application/pdf
MDPI
oai:uvadoc.uva.es:10324/528212022-08-24T09:01:11Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Routing, modulation and spectrum assignment algorithm using multi-path routing and best-fit
Ruiz Pérez, Lidia
Durán Barroso, Ramón José
Miguel Jiménez, Ignacio de
Merayo Álvarez, Noemí
Aguado Manzano, Juan Carlos
Abril Domingo, Evaristo José
Optical networks
Redes ópticas
Producción Científica
Elastic Optical Networks (EONs) are a promising optical technology to deal with the ever-increasing traffic and the vast number of connected devices of the next generation of the Internet, associated to paradigms like the Internet of Things (IoT), the Tactile Internet or the Industry 4.0, to name just a few. In this kind of optical network, each optical circuit or lightpath is provisioned by means of superchannels of variable bandwidth. In this manner, only the necessary bandwidth to accommodate the demand is allocated, improving the spectrum usage. When establishing a connection, the EON control layer determines the modulation format to be used and allocates a portion of the spectrum in a sequence of fibers from the source to the destination node providing the user-demanded bandwidth. This is known as the routing, modulation level and spectrum assignment (RMSA) problem. In this work, we firstly review the most important contributions in that area, and then, we propose a novel RMSA algorithm, multi-path best-fit (MP-BF), which uses a split spectrum multi-path strategy together with a spectrum assignment technique (best-fit), and which jointly exploit the flexibility of EONs. A simulation study has been conducted comparing the performance of EONs when using MP-BF with other proposals from the literature. The results of this study show that, by using MP-BF, the network can increase its performance in terms of lightpath request blocking ratio and supported traffic load, without affecting the energy per bit or the computation time required to find a solution.
2022-04-19T07:02:22Z
2022-04-19T07:02:22Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1109/ACCESS.2021.3101998
IEEE Access, 2021, vol. 9. p. 111633-111650
2169-3536
https://uvadoc.uva.es/handle/10324/52821
eng
https://ieeexplore.ieee.org/document/9503371
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2021 IEEE Xplore
application/pdf
IEEE Xplore
oai:uvadoc.uva.es:10324/528222022-04-19T20:48:17Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Experimental validation of an SDN residential network management proposal over a GPON testbed
Merayo Álvarez, Noemí
Pintos, David de
Aguado Manzano, Juan Carlos
Miguel Jiménez, Ignacio de
Durán Barroso, Ramón José
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Optical networks
Redes ópticas
Software defined networking
Redes definidas por software
Producción Científica
We propose, and experimentally demonstrate, an SDN (Software Defined Networking) new management solution for legacy GPONs (Gigabit Passive Optical Networks), which allows users to dynamically control their residential networks by means of a management application. In this way, users can customize the allocation of resources (and set constraints, if desired) to connected devices in their residential network, fast and efficiently. This real-time customization enables new business models for network operators and service providers. As a proof of concept and to validate the management solution, we demonstrate, in a testbed environment, the operation of a dynamic network scenario where an operator has a business model in which users have a contracted basic bandwidth, but they are allowed to increase it temporarily when using highly demanding services.
Junta de Castilla y León (project VA085G19)
Ministerio de Ciencia, Innovación y Universidades (projects TEC2017-84423-C3-1-P and RED2018-102585-T)
INTERREG V-A España-Portugal (POCTEP) program (project 0677_DISRUPTIVE_2_E).
2022-04-19T07:17:52Z
2022-04-19T07:17:52Z
2021
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.osn.2021.100631
Optical Switching and Networking, 2021, vol. 42, 100631
1573-4277
https://uvadoc.uva.es/handle/10324/52822
eng
https://www.sciencedirect.com/science/article/pii/S157342772100028X?via%3Dihub
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2021 The Authors
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/528242022-04-19T20:48:22Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Designing an efficient clustering strategy for combined Fog-to-Cloud scenarios
Asensio, Adrián
Masip-Bruin, Xavi
Durán Barroso, Ramón José
Miguel Jiménez, Ignacio de
Ren, Guang-Jie
Daijavad, Shahrokh
Jukan, Admela
Machine learning
Aprendizaje automático
Producción Científica
The evolution of the Internet of Things (IoT) is imposing many distinct challenges, particularly to guarantee both wide and global systems communication, and to ensure an optimal execution of services. To that end, IoT services must make the most out of both cloud and fog computing (turning into combined fog–cloud scenarios), which indeed requires novel and efficient resource management procedures to handle such diversity of resources in a coordinated way. Most of the related works that can be found in the literature focus on resource mapping for service-specific execution in fog–cloud; however, those works assume a control and management architecture already deployed. Interestingly, few works propose algorithms to set that control architecture, necessary to execute the services and effectively implement services and resource mapping. This paper addresses that challenge by solving the problem of optimal clustering of devices located at the edge of the network offering their resources to support fog computing while defining the control and management role of each of them in the architecture, in order to ensure access to management functions in combined fog–cloud scenarios. In particular, we set out the Fog–Cloud Clustering (FCC) problem as an optimization problem, which is based on multi-objective optimization, including realistic, novel and stringent constraints; e.g., to improve the architecture’s robustness by means of a device acting as a backup in the cluster. We model the FCC problem as a Mixed Integer Linear Programming (MILP) formulation, for which a lower and an upper bound on the number of required clusters is derived. We also propose a machine learning-based heuristic that provides scalable and near-optimal solutions in realistic scenarios in which, due to the high number of connected devices, solving the MILP formulation is not viable. By means of a simulation study, we demonstrate the effectiveness of the algorithms comparing its results with those of MILP formulation.
Spanish Thematic Networks (contracts RED2018-102585-T and TEC2015-71932-REDT)
Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (projects RTI2018-094532-B-I00 and TEC2017-84423-C3-1-P)
INTERREG V-A España-Portugal (POCTEP) program (project 0677_DISRUPTIVE_2_E).
2022-04-19T08:02:33Z
2022-04-19T08:02:33Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1016/j.future.2020.03.056
Future Generation Computer Systems, 2020, vol. 109, p. 392-406
0167-739X
https://uvadoc.uva.es/handle/10324/52824
eng
https://www.sciencedirect.com/science/article/pii/S0167739X19329541?via%3Dihub
info:eu-repo/grantAgreement/EC/H2020/730929
Attribution-NonCommercial-NoDerivatives 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by-nc-nd/4.0/
© 2020 Elsevier
application/pdf
Elsevier
oai:uvadoc.uva.es:10324/528252022-04-19T20:48:25Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
Genetic algorithm for holistic VNF-mapping and virtual topology design
Ruiz Pérez, Lidia
Durán Barroso, Ramón José
Miguel Jiménez, Ignacio de
Merayo Álvarez, Noemí
Aguado Manzano, Juan Carlos
Rosa Steinz, Ramón de la
Fernández Reguero, Patricia
Lorenzo Toledo, Rubén Mateo
Abril Domingo, Evaristo José
Optical networks
Redes ópticas
Producción Científica
Next generation of Internet of Things (IoT) services imposes stringent requirements to the future networks that current ones cannot fulfill. 5G is a technology born to give response to those requirements. However, the deployment of 5G is also accompanied by profound architectural changes in the network, including the introduction of technologies like multi-access edge computing (MEC), software defined networking (SDN), and network function virtualization (NFV). In particular, NFV poses diverse challenges like virtual network function (VNF) placement and chaining, also called VNF-mapping. In this paper, we present an algorithm that solves VNF-placement and chaining in a metro WDM optical network equipped with MEC resources. Therefore, it solves the VNF-mapping in conjunction with the virtual topology design of the underlying optical backhaul network. Moreover, a version of the method providing protection against node failures is also presented. A simulation study is presented to show the importance of designing the three problems jointly, in contrast to other proposals of the literature that do not take the design of the underlying network into consideration when solving that problem. Furthermore, this paper also shows the advantages of using collaboration between MEC nodes to solve the VNF-mapping problem and the advantage of using shared protection schemes. The new algorithm outperforms other proposals in terms of both service blocking ratio, and number of active CPUs (thus reducing energy consumption). Finally, the impact of deploying different physical topologies for the optical backhaul network is also presented.
Ministerio de Economía, Industria y Competitividad (grant TEC2017-84423-C3-1-P)
Ministerio de Industria, Comercio y Turismo (grant BES 2015-074514)
Spanish Thematic Network (contract RED2018-102585-T)
INTERREG V-A España-Portugal (POCTEP) program (project 0677_DISRUPTIVE_2_E)
2022-04-19T08:26:25Z
2022-04-19T08:26:25Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1109/ACCESS.2020.2982018
IEEE Access, 2020, vol. 8. p. 55893 - 55904
2169-3536
https://uvadoc.uva.es/handle/10324/52825
eng
https://ieeexplore.ieee.org/document/9042229
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 IEEE Xplore
application/pdf
IEEE Xplore
oai:uvadoc.uva.es:10324/528402022-04-20T23:59:31Zcom_10324_1191com_10324_931com_10324_894col_10324_1379
NFV and SDN-based differentiated traffic treatment for residential networks
Flores Moyano, Ricardo
Fernández Cambronero, David
Merayo Álvarez, Noemí
Lentisco, Carlos M.
Cárdenas, Andrés
Residential networks
Redes residenciales
Producción Científica
Residential networks play a critical role in assuring that services or applications such as tele-work, tele-education, medical care, entertainment, home automation, among others, have the required resources to obtain an optimal performance. Although current residential gateways try to meet the Quality of Service (QoS) demands, the traditional networking paradigm does not have the appropriate mechanisms to address the heterogeneous and dynamic nature of the services running at home. In this context, a feasible solution consists of leveraging the flexibility and adaptability of the Software Defined Networking (SDN) and Network Functions Virtualization (NFV) paradigms to provide a differentiated traffic treatment intended to improve the QoS support of residential networks. The proposal takes advantage of the Service Function Chaining (SFC) concept intrinsic to NFV as well as the capacity of an SDN-based residential gateway to differentiate the traffic of a certain application. Thus, an association between an SFC and the differentiated traffic is stablished to apply a specific treatment. Besides, a comprehensive architecture composed of the software defined residential network (SDRN), the software defined access network (SDOAN) and the NFV-compliant ISP's edge cloud infrastructure is envisioned. This architecture would allow dramatically improving the life cycle management of the residential network from a centralized point which follows a user-centric approach.
Ministerio de Ciencia, Innovación y Universidades (grants TEC2015-67834-R, TEC2017-84423-C3-1-P, RED2018-102585-T and 0677_DISRUPTIVE_2_E)
2022-04-20T06:56:37Z
2022-04-20T06:56:37Z
2020
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
https://doi.org/10.1109/ACCESS.2020.2974504
IEEE Access, 2020, vol. 8. p. 34038 - 34055
2169-3536
https://uvadoc.uva.es/handle/10324/52840
eng
https://ieeexplore.ieee.org/document/9000891
Atribución 4.0 Internacional
info:eu-repo/semantics/openAccess
http://creativecommons.org/licenses/by/4.0/
© 2020 IEEE Xplore
application/pdf
IEEE Xplore
oai_dc///col_10324_1379/100