Persona: Hernández del Olmo, Félix
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0000-0002-0567-9572
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Hernández del Olmo
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Félix
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Publicación An Adaptive, Comprehensive Application to Support Home-Based Visual Training for Children With Low Vision(IEEE, 2019) Matas, Yolanda; Santos, Carlos; Hernández del Olmo, Félix; Gaudioso Vázquez, ElenaLow vision is a visual impairment that cannot be improved by standard vision aids such as glasses. Therefore, to improve their visual skills, people affected by low vision usually follow a visual training program planned and supervised by an expert in this eld. Visual training is especially suitable for children because of their plasticity for learning. However, due to a lack of specialists, training sessions are usually less frequent than optimal. Thus, home-based visual training has emerged as a solution to this problem because it can be undertaken by experts and families together. We implemented the Visual Stimulation on the Internet (EVIN) application, which provides comprehensive visual training tasks through games. It also provides reports on children's performance in these visual training tasks. Although EVIN has shown its usefulness in previous works, two main solutions are needed: (i) a support setup to help experts and families work together to address, among other things, the large variety of exercises and different congurations that can be prescribed and (ii) a rigorous experimental design to compare children trained with EVIN and those trained with traditional materials. To face these challenges, we present an adaptive version of EVIN that provides a new design tool that allows experts to plan visual training tasks through templates in advance. In addition, we developed new metrics and reports to achieve a more accurate assessment of a child's improvement. Among other results, it allowed us to develop an reliable experiment to evaluate signicant improvements in children trained with EVIN.Publicación Tackling the start-up of a reinforcement learning agent for the control of wastewater treatment plants(Elsevier, 2018) Hernández del Olmo, Félix; Gaudioso Vázquez, Elena; Dormido Canto, Raquel; Duro Carralero, NatividadReinforcement learning problems involve learning by doing. Therefore, a reinforcement learning agent will have to fail sometimes (while doing) in order to learn. Nevertheless, even with this starting error, introduced at least during the non-optimal learning stage, reinforcement learning can be affordable in some domains like the control of a wastewater treatment plant. However, in wastewater treatment plants, trying to solve the day-to-day problems, plant operators will usually not risk to leave their plant in the hands of an inexperienced and untrained reinforcement learning agent. In fact, it is somewhat obvious that plant operators will require firstly to check that the agent has been trained and that it works as it should at their particular plant. In this paper, we present a solution to this problem by giving a previous instruction to the reinforcement learning agent before we let it act on the plant. In fact, this previous instruction is the key point of the paper. In addition, this instruction is given effortlessly by the plant operator. As we will see, this solution does not just solve the starting up problem of leaving the plant in the hands of an untrained agent, but it also improves the future performance of the agent.Publicación Machine Learning Weather Soft-Sensor for Advanced Control ofWastewater Treatment Plants(MDPI, 2019) Hernández del Olmo, Félix; Gaudioso Vázquez, Elena; Duro Carralero, Natividad; Dormido Canto, RaquelControl of wastewater treatment plants (WWTPs) is challenging not only because of their high nonlinearity but also because of important external perturbations. One the most relevant of these perturbations is weather. In fact, different weather conditions imply different inflow rates and substance (e.g., N-ammonia, which is among the most important) concentrations. Therefore, weather has traditionally been an important signal that operators take into account to tune WWTP control systems. This signal cannot be directly measured with traditional physical sensors. Nevertheless, machine learning-based soft-sensors can be used to predict non-observable measures by means of available data. In this paper, we present novel research about a new soft-sensor that predicts the current weather signal. This weather prediction differs from traditional weather forecasting since this soft-sensor predicts the weather conditions as an operator does when controling the WWTP. This prediction uses a model based on past WWTP influent states measured by only a few physical and widely applied sensors. The results are encouraging, as we obtained a good accuracy level for a relevant and very useful signal when applied to advanced WWTP control systems.Publicación Automatic assignment of reviewers in an online peer assessment task based on social interactions(Wiley Online Library, 2019) Anaya, Antonio R.; Luque Gallego, Manuel; Letón Molina, Emilio; Hernández del Olmo, FélixOnline peer assessment tasks are very popular and have unique characteristics that improve learning and encourage social interactions in a distance education environment. Unfortunately, social factors have usually been ignored in the process of selecting reviewers for online peer assessment tasks. We hypothesise that this fact could have some influence on the lack of engagement and participation by some learners. For this reason, we propose an approach in which social network analysis techniques, expert criteria, and Bayesian reasoning are applied to select reviewers with the objective of increasing participation in peer review tasks. The approach is divided into two elements. On the one hand, we have developed an influence diagram template that structures a set of proposed social network analysis variables in accordance with expert criteria. This influence diagram template can be easily updated for any course simply by eliciting a minimal set of parameters. On the other hand, we have instantiated the proposed influence diagram template to produce an influence diagram network to quantify the quality of reviewer assignment for an online peer assessment task. In an online experiment, we verified that the consideration of social factors can increase participation in a peer assessment task.