https://uvadoc.uva.es/handle/10324/1338 Dpto. Ingeniería Agrícola y Forestal - Artículos de revista 2026-04-11T23:16:42Z https://uvadoc.uva.es/handle/10324/83993 Photovoltaic power plants require module inspections to detect failures, thereby avoiding safety issues and optimizing overall operation. Luminescence imaging acquisition offers a viable solution for photovoltaic inspections, providing valuable information about module performance. This article presents a novel technique termed passive electroluminescence and photoluminescence, capable of producing luminescence images under daylight conditions by using sunlight or string current as excitation sources for photoluminescence and electroluminescence modulation, respectively. To achieve this modulation, an electronic board has been developed, which connects within a photovoltaic string and allows for measurements during the normal operation of the plant. The study focuses on analysing two strategies: synchronous and asynchronous lock-in approaches. While the synchronous method requires coordination between the camera and the electronic board, the asynchronous method operates independently of such synchronization. Although both strategies have been successfully validated, results indicate that the asynchronous strategy is faster and simpler to implement, whereas the synchronous approach may yield slightly higher quality results. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/83917 The estimation of series resistance in photovoltaic (PV) cells is a crucial parameter that significantly influences their efficiency and overall performance. This study proposes a novel methodology to predict the slope of the current–voltage (Ⅰ–Ⅴ) curve of a PV cell in the first quadrant, where this slope (the electrical conductance) is directly associated with the series resistance of the cell. By leveraging artificial intelligence techniques, a convolutional neural network model has been developed to estimate this slope from electroluminescence (EL) images of the cells. The model was trained on a dataset consisting of EL images of PV cells with artificially induced defects, together with the corresponding slope values derived from the cells' Ⅰ–Ⅴ curves. Furthermore, this work presents a second model that combines the slope information and EL images to improve the prediction of the maximum power point (MPP) of a PV cell, surpassing previous approaches that rely solely on EL imagery. Both models demonstrated low error rates across multiple evaluation metrics, evidencing their accuracy and robustness. Additionally, comparative analysis with other machine learning methods highlights the competitive performance of the proposed approaches. These contributions provide promising tools for enhancing the assessment and diagnosis of PV cell efficiency and reliability, potentially leading to improved performance and increased longevity of photovoltaic systems. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/83754 This manuscript introduces two Adaptive Neuro-Fuzzy Inference Systems developed to predict the energy output of Photovoltaic cells. These models are trained using Electroluminescence imagery of the cells for input data along their Current–Voltage curves, which offer insights output power of cells. The input characteristics of the cells are quantified based on pixel distribution and classified into three distinct categories: Black, White, and Gray values. The second model enhances this representation by incorporating an additional fuzzy categorization input, derived from a Mamdani Classifier Fuzzy Logic Model. By combining the rule-based interpretability of Fuzzy Logic with the adaptive learning capabilities of Artificial Neural Networks, the Adaptive Neuro-Fuzzy Inference System (ANFIS) emerges as an alternative to Convolutional Neural Networks (CNNs). This approach contributes to Explainable Artificial Intelligence by addressing one of the major limitations of CNNs—the lack of symbolic knowledge representation, while maintaining robust learning performance. Comparative analysis with other Machine Learning techniques demonstrates the enhanced performance provided by ANFIS models, achieving a Mean Absolute Error (MAE) of 0.053 and a Mean Squared Error (MSE) of 0.007. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/83311 Overripening of grapes, due to global warming, can result in unbalanced wines with higher alcohol content, lower acidity and an altered sensory profile. Pre-fermentative treatment of the must with a glucose oxidase- catalase enzyme system immobilized in silica‑calcium-alginate hydrogel capsules degraded up to 17.3% of the glucose in the must in 48 h to obtain wines with 1.0–1.3% vol (v/v) lower alcoholic strength. Most of the gluconic acid produced by glucose oxidation was retained in the capsules, resulting in a mild reduction in the pH, thereby avoiding a strong acidification of the must. The remainder of the gluconic acid present in the must was largely degraded during the fermentation process using a selected strain of the yeast Schizosaccharomyces pombe (S. pombe). Both the enzymatic treatment of the must with the capsules and the use of S. pombe, either in unique inoculation or in sequential inoculation with a Saccharomyces cerevisiae (S. cerevisiae), led to balanced wines with a unique chemical profile. The combination of these two strategies, pre-fermentative and fermentative, presents an innovative and promising approach, not investigated so far, to counteracting the adverse effects of rising temperatures due to global warming. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/83091 This paper presents the design, construction, and calibration of a modular low-cost 3D printer based on open-source technologies, developed as part of an academic research project. The printer utilises fused filament fabrication (FFF) and is built using locally available materials and components, including a T-slot aluminium frame, NEMA 23 stepper motors, and an Arduino Mega 2560 with RAMPS 1.4 control board. The system integrates Marlin firmware and CURA slicing software, enabling autonomous operation via an LCD panel and encoder interface. A detailed methodology is provided for mechanical assembly, electronic integration, firmware configuration, and calibration procedures. Special attention is given to the challenges encountered during the initial testing phase, including filament feeding issues, thermal inconsistencies, and mechanical misalignments. Solutions such as replacing inadequate components (e.g., fibreglass bushings with PTFE), adjusting spring tension, and refining firmware parameters are discussed. The results demonstrate successful printing of complex geometries after iterative calibration, validating the printer’s performance and replicability. This work contributes to the democratisation of additive manufacturing by offering a replicable, open-source solution for educational and prototyping purposes. The findings are relevant to machine design, automation, and robotics communities seeking practical insights into low-cost fabrication systems. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82998 Intensive farming causes an important amount of greenhouse gas emissions. This scenario can be significantly reduced by the implementation of renewable technologies and transforming farms from energy consumers to energy providers. In the particular case of livestock production, biogas and solar energy reduce greenhouse gas emissions and the energy demand of the installations. However, the implementation of these technologies requires solutions adapted to local scenarios, such as connectivity to the energy grids. In this work, a biogas/biomethane production system, energetically covered with hybrid solar panels is proposed as a solution for isolated areas where biodegradable substrates (manure) are abundant. Thus, the electrical and thermal requirements of the digester are supplied by solar panels, reducing the biogas self-consumption and the energy inputs from the electrical grid. Hybrid solar panels also provide sufficient energy for operation of an upgrading system to obtain biomethane of fuel vehicle quality, increasing the energy self-sufficiency of the agricultural activities. This solution has been simulated in five different climatic regions corresponding to areas of intense pig farming activity. The results demonstrate the sustainable bioenergy production in isolated farms with limited connection to the energy grid and organic matter availability. Furthermore, the economic study showed that the proposed technology is competitive compared to other technologies in the energy sector. 2023-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82674 The transportation sector is a significant contributor to global greenhouse gas emissions, demanding the adoption of low-carbon technologies. This study focuses on the economic assessment of two types of hybrid electric vehicles as taxis in Brazil, exploring their potential to ease electric vehicle adoption and contribute to decarbonizing the transportation sector. Environmental life cycle cost, net present value, and total cost of ownership were calculated for hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs), as taxis and private cars, fuelled by different fuels, in single-fuel and dual-fuel modes. It also compares the Brazilian scenario with Spain and the United Kingdom to examine their economic benefits, considering factors such as purchase costs, operating expenses, and government incentives. Results show that taxis outperform private cars in return on investment, with Spain performing best due to its lower discount rate. Brazil ranked between Spain and the United Kingdom in ELCC and TCO but was the least favourable in NPV. Overall, the research highlights that taxis are identified as a practical short-term alternative for introducing electric vehicles in Brazil, proving to be more economically favourable than private vehicles. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82666 The indoor cultivation of Matricaria chamomilla represents a promising strategy for optimizing medicinal plant production. This research evaluated the effects of LED spectral composition on the morphological and biochemical development of chamomile in an aeroponic system. Three light treatments were applied: Red predominant + Far-red + Blue (Rh + FR + B), Blue predominant + Red + Far-red (Bh + R + FR), and Red + Blue (R + B), with a photosynthetic photon flux density (PPFD) of 255.96 ± 5.8 µmol m−2 s−1. Seedlings were germinated under controlled conditions and later transferred to an aeroponic system with mist irrigation. The treatment Bh + R + FR significantly enhanced flowering, increasing flower and bud production, floral head diameter, and petal length. In contrast, R + B promoted higher chlorophyll accumulation and nitrogen balance index, favoring greater leaf expansion, particularly in pinna length. Although anthocyanin and flavonoid concentrations increased over time in all treatments, their accumulation was not significantly affected by spectral composition. These findings highlight that optimizing chamomile flower production requires a higher proportion of blue light, while a balanced red-to-blue ratio is more effective for maximizing leaf development. This study provides new insights into spectral optimization for controlled M. chamomilla cultivation, supporting its application in the medicinal and aromatic plant industry. 2026-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/82072 The Brazilian electricity matrix is around 80% renewable, and it has registered continuous growth in the expansion of biogas and photovoltaic (PV) systems. The main current Brazilian incentive program for the distributed generation of renewable energy, through a single net metering tariff, that is, a generation compensation system in credits to the consumer who owns the generating unit, does not seem to be effective to promote the expected growth of the biogas. Thus, the objective of this paper was to evaluate quantitatively and qualitatively a set of significant externalities for both sources to contribute to a more realistic energy planning. The externalities quantitatively evaluated for these two renewable sources were: avoided emissions, employment and income, biofertilizers for biogas and use as a constructive element for PV systems. A significant result was that the economic value of the externalities of biogas can exceed those of PV systems for the rural producer by more than 11 times, for society by 1.7 times. It is concluded that, due to the value of biogas externalities being much higher economically than those of PV systems, Brazilian public policies for energy planning should prioritize biogas over solar photovoltaic energy systems. 2024-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81642 This study aims to describe pre-reproductive movements of Luciobarbus bocagei and Pseudochondrostoma duriense in a regulated canyon-stretch of the Tormes River (Spain), with high environmental variability, semipermeable barriers, and fishway retrofitting actions. The main objectives were to identify peak migration dates and environmental drivers, test ensemble-learning techniques to model fish migration and propose adaptive management measures. To achieve this, fish movements were 5-year monitored in a stepped fishway and Survival Analysis and Random Forest techniques were used for data analysis and modelling. Results showed that migration occurred in May–July, a wider period than the one previously reported in the literature. Movements were triggered by the increase in water temperature and photoperiod, and were strongly affected by the hydraulic river scenario (water levels and discharge) at the semipermeable barriers. Random Forest was able to include the effect of each barrier and predict accurately timing and number of migrants, classifying and ranking the importance of variables. Moreover, developed models allowed to assess fishway retrofitting actions and to predict positive effects in fish number under new, scheduled and variable environmental flow scenarios. Long-term monitoring together with ensemble-learning methods can allow the definition of cost-effective adaptive management strategies to ensure endemic fish conservation. 2022-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81597 Restoring the longitudinal connectivity of rivers is one of the main objectives of environmental European directives and policies. Fish passes or fishways are one of the most common actions for its restoration. Despite the great number of fish passes constructed during the last two decades to comply with these policies, few of them have been assessed and their suitability for fish movements is unknown. There are different options to assess fish passes, but time and economic costs frequently limit their application. Coarse fishway assessment methods (CFAMs) are an easy, fast and economic alternative for this purpose. This study aims to display the potential of CFAMs to evaluate a large number of fishways, to show the actual status of fishways in an Iberian representative river basin, and to diagnose their suitability and problems. For this, the Spanish Duero River Authority promoted the assessment of 64 stepped fishways in the Duero River basin (Spain) using the AEPS methodology. The results were analyzed considering the four stages that a fish must overcome in a fishway (attraction, entry, passage and exit), the fishway type and the construction period. Among others, results show that 50% of the assessed fishways allow the free movement of fish. However, this percentage could have been greater applying an adequate monitoring program for the fishway design and construction. Furthermore, the diagnosis by stages of the AEPS methodology allowed to identify the attraction and passage as the most problematic stages and also helped to define specific retrofitting solutions for each fishway. The study concludes that the application of CFAM during fishway design, construction and first operation stages can increase their effectiveness and, thus, the number of fish passes that contribute to the restoration of the longitudinal connectivity of rivers. 2020-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81580 The objective of this study is to make a comparison between two 3D CFD platforms: OpenFOAM (free and open-source CFD software) and FLOW-3D (closed source commercial CFD software), focusing on vertical slot fishways, one of the most widespread solutions to facilitate the fish migration through transversal obstacles in rivers. Considering previous comparative studies, our initial hypothesis is that both OpenFOAMs' multiphase solver and FLOW-3D provide good comparable results. In this study, in contrast to previous comparative studies, turbulence was addressed using LES approach and the volume of fluid method was used to model the multiphase interface (air-water). Mesh independency was assessed through LES IQ index and the numerical models' accuracies were evaluated comparing representative hydraulic variables (velocity, its components, and turbulence kinetic energy) with ADV experimental data and discussing results in previous studies. Both platform codes reproduced the scenario under study, concurred with experimental data and offered a superior performance on flow structure velocity simulation than turbulent kinetic energy. Results validate the use of the free and open platform OpenFOAM as a viable alternative to commercial ones in the domain of fishway design and assessment. While OpenFOAM provides a reliable free alternative, FLOW-3D has a faster setup and makes the simulating experience apt for beginners. 2022-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81575 Global stocks of freshwater fish have been on the decline for decades, driven in part by the obstruction of their migration routes by anthropogenic barriers. To mitigate such impacts, fishways have been developed to facilitate bidirectional fish migration. These structures are affected by the hydrological variability of rivers, which can cause changes in the up and downstream boundary conditions of fishways, leading to non-uniform hydraulic performance. Current methodologies in fishway design and analysis often assume uniform performance, most commonly relying on 1D approximations of the water level distribution. In this study we highlight the necessity of considering non-uniform performance. We provide an in-depth analysis methodology for non-uniform conditions, demonstrating the necessity of 3D models to correctly characterize non-uniformity and leveraging the synergy between 1D and 3D models. For this VOF method together with two turbulence modelling technics, RANS Standard k-ε and LES Smagorinsky models, are analyzed using OpenFOAM CFD platform. 2018-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81571 Vertical slot fishways (VSFs) are hydraulic structures which allow fish to swim around obstacles in rivers. These structures are subject to variations in discharge of either hydrological or operational origin, which result in non-uniform water depth profiles, i.e. differences in the water drops across the slots (ΔH) and mean depths (h0) across the pools. Although non-uniform conditions are present in most VSFs, they are rarely considered in the design and evaluation of fishways. The aim of this work is to provide an introductory analysis of how non-uniform water depth profiles affect the hydrodynamics within the pools of VSFs. This study shows that flow patterns are controlled by changes in ΔH and h0 in addition to slope and other geometrical alterations, as previously suggested. Non-uniformity alters the flow structure in pools and the spatial distributions of hydrodynamic variables. Consequently, critical thresholds of hydrodynamic variables for fish may be reached in VSFs designed with recommended slopes when operating under non-uniform conditions. 2019-02-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81559 Today, there is a trend in enology promoting a return to the use of old natural materials for the manufacture of storage and maturation wine tanks. One of the most sought-after characteristics of these materials is their permeability to oxygen from the atmosphere to improve wines without this being a harmful process. The reference performance in wine aging is, without doubt, the oak barrel for its ability to oxidize wines in a controlled way, thus improving them. It would be possible to mature wines in containers in which the use of wood is not obligatory, as opposed to aging in oak barrels or foudres. This work presents the results of oxygen permeation analysis under test conditions typical of a tank containing wine, using materials, such as concrete and granite. The oxygen permeability of the materials tested was very diverse, typical of natural materials. The results showed that earthenware presents an excessive permeability, not only to atmospheric oxygen, but also to liquids and needs treatment before being used in liquid containers. Claystone and concrete can be impermeable to liquids, but maintain permeability to atmospheric oxygen—making them candidates for use in permeable tanks for wine maturation. Finally, granite has some very interesting characteristics, though thickness control is required when calculating the desired oxygen transmission rate. 2021-01-01T00:00:00Z https://uvadoc.uva.es/handle/10324/81557 American and French oak are woods commonly used in cooperage to make barrels. This study analyzed 250 French oak staves to determine the relationship between ellagitannin content and oxygen consumption capacity, as well as the importance of wood grain and its oxygen transfer rate. The study found that castalagin is the most abundant ellagitannin, followed by vescalagin in 37 % of the staves and roburin E in 46 % of them. This allows for the creation of ellagitannin content profiles. It was observed that vescalagin and castalagin occupied the top positions in 7 % of the samples. Additionally, the woods with the highest oxygen consumption capacity were found to have castalagin or vescalagin as the main ellagitannins. Samples with castalagin and roburin E as the main ellagitannins had the lowest consumption capacity. Seven percent of the samples had a castalagin and roburin D profile, which was found to be intermediate. 2025-01-01T00:00:00Z