Analysis of calibration results from cup and propeller anemometers. Influence on wind turbine Annual Energy Production (AEP) calculations

The calibration coefficients of several models of cup and propeller anemometers were analysed. The analysis was based on a series of laboratory calibrations between January 2003 and August 2007. Mean and standard deviation values of calibration coefficients from the anemometers studied were included. Two calibration procedures were used and compared. In the first, recommended by the Measuring network of Wind Energy Institutes (MEASNET), 13 measurement points were taken over a wind speed range of 4 to 16  m  s−1. In the second procedure, 9 measurement points were taken over a wider speed range of 4 to 23  m  s−1. Results indicated no significant differences between the two calibration procedures applied to the same anemometer in terms of measured wind speed and wind turbines' Annual Energy Production (AEP). The influence of the cup anemometers' design on the calibration coefficients was also analysed. The results revealed that the slope of the calibration curve, if based on the rotation frequency and not the anemometer's output frequency, seemed to depend on the cup center rotation radius.

Automatic expert system based on images for accuracy crop row detection in maize fields

This paper proposes an automatic expert system for accuracy crop row detection in maize fields based on images acquired from a vision system. Different applications in maize, particularly those based on site specific treatments, require the identification of the crop rows. The vision system is designed with a defined geometry and installed onboard a mobile agricultural vehicle, i.e. submitted to vibrations, gyros or uncontrolled movements. Crop rows can be estimated by applying geometrical parameters under image perspective projection. Because of the above undesired effects, most often, the estimation results inaccurate as compared to the real crop rows. The proposed expert system exploits the human knowledge which is mapped into two modules based on image processing techniques. The first one is intended for separating green plants (crops and weeds) from the rest (soil, stones and others). The second one is based on the system geometry where the expected crop lines are mapped onto the image and then a correction is applied through the well-tested and robust Theil–Sen estimator in order to adjust them to the real ones. Its performance is favorably compared against the classical Pearson product–moment correlation coefficient.

Automatic design of Ant Colony Optimization for permutation problems

In this study, we present a framework based on ant colony optimization (ACO) for tackling combinatorial problems. ACO algorithms have been applied to many diferent problems, focusing on algorithmic variants that obtain high-quality solutions. Usually, the implementations are re-done for various problem even if they maintain the same details of the ACO algorithm. However, our goal is to generate a sustainable framework for applications on permutation problems. We concentrate on understanding the behavior of pheromone trails and specific methods that can be combined. Eventually, we will propose an automatic offline configuration tool to build an efective algorithm. ---RESUMEN---En este trabajo vamos a presentar un framework basado en la familia de algoritmos ant colony optimization (ACO), los cuales están dise~nados para enfrentarse a problemas combinacionales. Los algoritmos ACO han sido aplicados a diversos problemas, centrándose los investigadores en diversas variantes que obtienen buenas soluciones. Normalmente, las implementaciones se tienen que rehacer, inclusos si se mantienen los mismos detalles para los algoritmos ACO. Sin embargo, nuestro objetivo es generar un framework sostenible para aplicaciones sobre problemas de permutaciones. Nos centraremos en comprender el comportamiento de la sendas de feromonas y ciertos métodos con los que pueden ser combinados. Finalmente, propondremos una herramienta para la configuraron automática offline para construir algoritmos eficientes.

Application of Improved Direct Calibration for Hyperspectral image processing: Detecting peanut traces in wheat flour.

NIR Hyperspectral imaging (1000-2500 nm) combined with IDC allowed the detection of peanut traces down to adulteration percentages 0.01% Contrary to PLSR, IDC does not require a calibration set, but uses both expert and experimental information and suitable for quantification of an interest compound in complex matrices. The obtained results shows the feasibility of using HSI systems for the detection of peanut traces in conjunction with chemical procedures, such as RT-PCR and ELISA

Calibration of calculation models of wooden guardrails with Operational Modal Analysis

This study analyses the differences between two calculation models for guardrails on building sites that use wooden boards and tubular steel posts. Wood was considered an isotropic material in one model and an orthotropic material in a second model. The elastic constants of the wood were obtained with ultrasound. Frequencies and vibration modes were obtained for both models through linear analysis using the finite element method. The two models were experimentally calibrated through operational modal analysis. The results obtained show that for the three types of wood under analysis, the model which considered them as an orthotropic material fitted the experimental results better than the model which considered them as an isotropic material.

Automatic quantification of matrix cracking and fiber rotation by X-ray computed tomography in shear-deformed carbon fiber-reinforced laminates

The deformation and damage mechanisms of carbon fiber-reinforced epoxy laminates deformed in shear were studied by means of X-ray computed tomography. In particular, the evolution of matrix cracking, interply delamination and fiber rotation was ascertained as a function of the applied strain. In order to provide quantitative information, an algorithm was developed to automatically determine the crack density and the fiber orientation from the tomograms. The investigation provided new insights about the complex interaction between the different damage mechanisms (i.e. matrix cracking and interply delamination) as a function of the applied strain, ply thickness and ply location within the laminate as well as quantitative data about the evolution of matrix cracking and fiber rotation during deformation

Optical in situ calibration of Sb to grow disordered GaInP by MOVPE

Reflectance anisotropy spectroscopy (RAS) was employed to determine the optimal specific molar flow of Sb needed to grow GaInP with a given order parameter by MOVPE. The RAS signature of GaInP surfaces exposed to different Sb/P molar flow ratios were recorded, and the RAS peak at 3.02 eV provided a feature that was sensitive to the amount of Sb on the surface. The range of Sb/P ratios over which Sb acts as a surfactant was determined using the RA intensity of this peak, and different GaInP layers were grown using different Sb/P ratios. The order parameter of the resulting layers was measured by PL at 20 K. This procedure may be extensible to the calibration of surfactant-mediated growth of other materials exhibiting characteristic RAS signatures.

Comportamiento hidrológico de cuencas de media montaña españolas: efectos de los procesos de acumulación / fusión de nieve en terrenos permeables sobre la infiltración y régimen de caudales Alto Tajo

La infiltración de agua en el suelo y la recarga profunda del agua subterránea contenida en los acuíferos es un proceso lento en relación con otros fenómenos hidrológicos. La redacción de esta tesis ha pretendido contribuir al estudio de la influencia que el almacenamiento de la precipitación sólida en forma de manto de nieve y su eventual fusión puedan tener sobre dicho proceso en áreas de media montaña (1.000 – 2.000 m.) en las que con gran frecuencia se sitúan las cabeceras de los ríos peninsulares. Para ello se ha partido del análisis de las diferentes variables intervinientes durante un determinado periodo temporal y sobre un espacio geográfico concreto, por lo que su metodología es de naturaleza empírica. La extensión del periodo (2002/03 a 2010/11) ha venido condicionada por la disponibilidad de los valores de algunas de sus principales variables, como han sido el equivalente en agua de la nieve acumulada y los caudales procedentes de su fusión. Éstos se han obtenido como resultado de la aplicación del modelo ASTER, desarrollado en el programa de Evaluación de los Recursos Hídricos procedentes de la Innivación (ERHIN), calibrado – entre otros- con datos de precipitaciones, temperatura y caudales provenientes a su vez del Sistema Automático de Información Hidrológica (SAIH). Ambos programas fueron implantados por la Administración en las diferentes Confederaciones Hidrográficas y en determinados Organismos de cuenca actuales, en cuyo desarrollo participó el autor de esta tesis. En cuanto a la zona de estudio se ha procedido a su elección considerando las posibles áreas de media montaña en las que la presencia de la nieve fuera hidrológicamente significativa y estuvieran constituidas litológicamente por afloramientos permeables que no impidieran la infiltración en el terreno y la formación de acuíferos de cierta relevancia. El interés se centró discrecionalmente en la cuenca del Tajo, tanto por el carácter estratégico de la misma -como suministradora en la actualidad de excedentes a otras cuencas deficitarias- como por el valor representativo de sus condiciones climáticas y orográficas en relación con otras cuencas hidrográficas peninsulares. Para ello se partió de las cabeceras de ríos identificadas por el programa ERHIN por su interés nivológico para la implantación del modelo ASTER y de las Masas de Agua Subterráneas MASb (antes Unidades Hidrogeológicas UUHH) definidas en los planes hidrológicos. La intersección en el territorio de ambos criterios condujo, finalmente, a la zona del Alto Tajo, en la que se cumplen ambos requisitos. El tramo quedó concretado en el comprendido entre las cabeceras de los ríos Tajo y Guadiela y la cola de los embalses de Entrepeñas y Buendía respectivamente, puntos de cierre para la calibración llevada a cabo en la modelización ASTER. Gran parte de éste discurre, en su parte alta, sobre rocas carbonatadas (calizas y dolomías del Jurásico y Cretácico), relacionados con las MASb de Tajuña-Montes Universales, Molina de Aragón y Sigüenza-Maranchón. Los valores diarios de las reservas de agua en forma de nieve, evapotranspiración y caudales procedentes de la fusión se han obtenido a partir de los resultados del mencionado modelo, procediéndose al cálculo de la infiltración por balance hídrico durante el periodo de estudio considerado, teniendo en cuenta los valores de precipitación, evapotranspiración y aportaciones de caudales. Esto ha requerido el estudio previo de las condiciones hidrogeológicas de la zona seleccionada con objeto de conocer las posibles interconexiones subterráneas que pudieran alterar los saldos entre las variables intervinientes anteriormente citadas. Para ello se ha llevado a cabo la recopilación y análisis de la información hidrogeológica correspondiente a la documentación de los planes hidrológicos del Tajo (Plan Hidrológico de la cuenca del Tajo RD 1664/1998 y el actual Plan Hidrológico de la parte española de la Demarcación Hidrográfica del Tajo RD 270/2014) y de los estudios previos realizados por el organismo de cuenca y el Instituto Geológico y Minero de España (lGME) fundamentalmente. En relación con la MASb Tajuña-Montes Universales -cuya extensión supera la zona seleccionada- dichos estudios consideran su estructura geológica y distribución litológica, con intercalaciones impermeables que actúan como barreras, dividiendo a éstas en Subunidades e identificando las zonas de drenaje de sus respectivos acuíferos. También se ha considerado la documentación y estudios previos del Plan Hidrológico Nacional sobre las Unidades Hidrogeológicas compartidas entre ámbitos geográficos de diferentes planes hidrológicos. Se concluye que las divisorias hidrográficas de las cabeceras son sensiblemente coincidentes o abarcan las Subunidades Montes Universales meridionales, Priego, Cifuentes, Zaorejas, u Montes Universales septentrionales, que drenan hacia el Tajo/Guadiela (bien directamente, bien a través de afluentes como el Gallo, Ablanquejo, Cabrillas, Cuervo…), MASb Molina de Aragón, que drena al Tajo a través del río Gallo y MASb Sigüenza—Maranchón, que drena su parte correspondiente hacia el Tajo a través del Ablanquejo. Se descartan – salvo la pequeña salvedad del manantial de Cifuentes- las conexiones hidrogeológicas con otras MASb o Subunidades por lo que las cabeceras del Tajo y del Guadiela pueden considerarse como un Sistema independiente donde las precipitaciones no evaporadas escurren superficialmente o se infiltran y descargan hacia los embalses de Entrepeñas y Buendía. La cuantificación diaria y acumulada de los balances hídricos ha permitido calcular la evolución aproximada de las reservas de agua subterránea desde la fecha inicial. Originalmente los balances se realizaron de forma separada en las cabeceras del Tajo y del Guadiela, cuyos valores acumulados manifestaron una tendencia creciente en la primera y decreciente en la segunda. Dicha situación se equilibra cuando el balance se practica conjuntamente en ambas, apreciándose en la variación del volumen de agua subterránea una evolución acorde hidrológicamente con los ciclos de verano/invierno y periodos de sequía, manteniéndose sus valores medios a largo/medio plazo, poniendo en evidencia la existencia de interconexiones subterráneas entre ambas cuencas. El balance conjunto, agregando la cabecera del Tajuña (que también comparte los materiales permeables de la MASb Tajuña-Montes Universales) no reveló la existencia de nuevas interrelaciones hidrogeológicas que influyeran en los balances hídricos realizados Tajo/Guadiela, confirmando las conclusiones de los estudios hidrogeológicos anteriormente analizados. Se ha procedido a confrontar y validar los resultados obtenidos de la evolución de las reservas de agua subterránea mediante los siguientes procedimientos alternativos: - Cálculo de los parámetros de desagüe de la curva de agotamiento correspondiente al volumen de agua subterránea drenante hacia el Tajo/Guadiela. Éste se ha realizado a partir de las aportaciones mensuales entrantes en los embalses de Entrepeñas y Buendía durante los meses de junio, julio, agosto y septiembre, cuyos valores responden al perfil típico de descargas de un acuífero. A partir de éstos se ha determinado el volumen drenante correspondiente al primero de junio de cada año de la serie histórica considerada. - Determinación del caudal base por el método Wallingford y deducción de los volúmenes drenantes. Estimación de las recarga anuales - Cuantificación de la recarga anual por el método Sanz, Menéndez Pidal de Navascués y Távara. Se obtuvieron valores de recarga muy aproximados entre los calculados por los dos últimos procedimientos citados. Respecto a las reservas de agua subterránea almacenadas siguen una evolución semejante en todos los casos, lo que ha permitido considerar válidos los resultados conseguidos mediante balance hídrico. Confirmada su solidez, se han buscado correlaciones simples entre el volumen de las reservas subterráneas (como indicador estimativo del efecto de la infiltración) y los volúmenes procedentes de la fusión. La conclusión es que estos últimos no tienen un efecto determinante a escala anual sobre la infiltración,recarga y variación de los volúmenes de agua subterránea, frente al peso de otras variables (precipitación y evapotranspiración). No obstante se ha encontrado una buena correlación múltiple entre la recarga estimada y la precipitación eficaz (precipitación menos evapotranspiración) y fusión, que ha permitido cuantificar la contribución de esta última. Posteriormente se ha recurrido a la selección de los episodios más intensos de acumulación /fusión en las cabeceras del Tajo y Guadiela. Y se procedió a la comparación entre los resultados obtenidos por aplicación del modelo de simulación en los mismos periodos (normalmente de varios días de duración) con datos reales y con datos ficticios de temperatura que anularan o disminuyeran la presencia de nieve, apreciándose una gran sensibilidad del efecto de la temperatura sobre la evapotranspiración y estableciéndose nuevamente correlaciones lineales entre los volúmenes de fusión y el incremento de reservas subterráneas. Las mismas confirman el efecto “favorecedor” de la acumulación de agua en forma de nieve y su posterior licuación, sobre sobre la infiltración de agua en el suelo y almacenamiento subterráneo. Finalmente se establecieron varios escenarios climáticos (+1ºC; +3ºC; +1ºC y – 10% precipitación; y 3ºC – 10% precipitación) compatibles con las previsiones del IPCC para mediados y finales del presente siglo, determinándose mediante simulación ASTER los correspondientes valores de fusión. La correlación establecida a escala anual ha permitido evaluar el efecto de la disminución del volumen de fusión - en los diferentes escenarios – sobre la recarga, pronosticando un descenso de los caudales de estiaje y la desaparición del “efecto nieve” sobre la infiltración y recarga con un aumento de 3ºC de temperatura. Teniendo en cuenta las condiciones de representatividad de la zona elegida, resulta verosímil la extensión de las anteriores conclusiones a otras cabeceras fluviales enclavadas en áreas de media montaña situadas entre 1000 a 2000m y sus efectos aguas abajo.Water infiltration into the soil and groundwater recharge deep water in aquifers is slow relative to other hydrological phenomena. The wording of this thesis aims to contribute to the study of the influence that the storage of solid precipitation as snow cover and its eventual melting may have on this process in mid-mountain areas (1000 - 2,000 m) where very often the headwaters of the peninsular rivers are located. For this party analysis of the different variables involved has over a given time period and a particular geographical area, so that their methodology is empirical in nature. The extension of the period (2002/03 to 2010/11) has been conditioned by the availability of the values of some of its key variables, as were the water equivalent of the snow and flows from melting. These have been obtained as a result of the application of ASTER model, developed in the program Evaluation of Water Resources from the Innivation (ERHIN), calibrated - among others data of rainfall, temperature and flow from turn System Automatic Hydrological Information (SAIH). Both programs were implemented by the Administration in the different Water Boards and to undertakings for current basin, in which the author participated development of this thesis. As for the study area has proceeded at its option considering the possible areas of midmountain in the presence of snow outside hydrological meaningful and they were lithology consisting of permeable outcrops that did not prevent infiltration into the ground and forming aquifers of some significance. We were interested discretion in the Tagus basin, therefore the strategic nature of it, as currently supplying surplus to other basins deficit- as the representative value of its climate and terrain conditions in relation to other peninsular river basins . To do this we started from the headwaters identified by the ERHIN program for its implementation snow interest to the ASTER model and Ground Water Bodies MASb (before UUHH Hydrogeological Units) defined in hydrological plans. The intersection in the territory of both criteria led eventually to the Alto Tajo, in which both requirements are met. The section was finalized in the period between the headwaters of the Tagus and Guadiela rivers and reservoirs end Entrepeñas and Buendia respectively checking points for calibration performed in ASTER modeling. Much of it runs on carbonate rocks (limestones and dolomites of Jurassic and Cretaceous) related MASb of Tajuña -Montes Universal, Molina de Aragón and Sigüenza-Maranchón. The daily values of water reserves in the form of snow, evapotranspiration and flow from melting were obtained from the results of this model, proceeding to the calculation of infiltration water balance during the study period considered, taking into account values of precipitation, evapotranspiration and input flow. This has required the prior examination of the hydrogeological conditions of your required in order to know the possible underground interconnections that could alter the balance between the intervening variables aforementioned area. For this we have carried out the collection and analysis of hydrogeological information relevant documentation Tagus river management plans (Hydrological Plan Tajo Basin RD 1664/1998 and the current Hydrological Plan of the Spanish part of the River Basin Tagus RD 270/2014) and previous studies by the basin organization and the Geological Survey of Spain (IGME) mainly. Regarding the MASb Tajuña- Montes Universal - whose length exceeds the area selected - these studies consider its geological structure and lithology distribution with waterproof collations that act as barriers, dividing it into subunits and identifying areas draining their respective aquifers. It has also considered the documentation and previous studies of the National Hydrological Plan on shared among different geographical areas management plans Hydrogeological Units. We conclude that river dividing the headers are substantially coincident or covering Subunits southern Universal Montes, Priego Cifuentes, Zaorejas and northern Universal Mounts, which drain into the Tagus / Guadiela (either directly or through tributaries such as Gallo, Ablanquejo , whitecaps , Raven ...), MASb Molina de Aragón which drains through the Tajo del Gallo and MASb Sigüenza- Maranchón river that drains into the Tagus using the Ablanquejo . Discarded - except the small exception of spring Cifuentes -hydrogeological connections with other MASb or Subunits so the headwaters of the Tagus and Guadiela be considered as a separate system, where rainfall not evaporated runs on surface or infiltrates and eventually discharged into reservoirs Entrepeñas and Buendia. The daily and cumulative quantification of water balances allowed us to compute the approximate evolution of groundwater reserves from its initial date. Initially balances were performed separately in the headwaters of the Tagus and Guadiela, whose cumulative values showed an increasing trend in the first and decreasing in the second. This situation is balanced when the balance is practiced together in both , appreciating the change in volume of groundwater hydrological evolution commensurate with the cycles of summer / winter and drought periods , keeping their average long / medium term values and putting in shows the existence of underground interconnections between the two basins. The overall balance, adding header Tajuña (which also shares the permeable materials MASb Tajuña -Montes Universal ) did not reveal the existence of new hydrogeological interrelationships that influenced water balances made Tajo / Guadiela, confirming the findings of the hydrogeological studies previously analyzed. We proceeded to confront and validate the results of the evolution of groundwater reserves by the following alternative procedures: - Calculate the parameters drain depletion curve corresponding to the volume of groundwater draining into the Tajo / Guadiela. This has been made from monthly inflows in the reservoirs of Entrepeñas and Buendia during the months of June, July, August and September, whose values match the typical profile of an aquifer discharges. From these has been determined for the first of June each year of the time series considered drainage volume - Determination of base flow by Wallingford method and deduction of drainage volumes. Estimate of annual recharge - Quantification of the annual recharge by the method Sanz Menéndez Pidal of Navascués and Távara. Very approximate values recharge between calculated for the last two mentioned methods were obtained. Concerning groundwater reserves stored follow a similar pattern in all cases, allowing consider valid the results achieved through water balance. Confirmed its robustness, simple correlations were sought between the volume of groundwater reserves (as estimated indicator of the effect of infiltration) and volumes from the melting. The conclusion is that the latter do not have a decisive effect on the annual scale infiltration, recharge and variation in volumes of groundwater, against the weight of other variables (precipitation and evapotranspiration). However found a good multiple correlation between the estimated recharge and effective precipitation (precipitation minus evapotranspiration) and fusion, which allowed quantify the contribution of the latter. Subsequently it has resorted to the selection of the most intense episodes of accumulation / melting in the headwaters of the Tagus and Guadiela. And we proceeded to the comparison between the results obtained by application of the simulation model in the same periods (usually several days) with real data and fictitious temperature data to annul or decrease the presence of snow, appreciating a great sensitivity of the effect of temperature on evapotranspiration and establishing linear correlations between the volumes of melting and increased groundwater reserves again. They confirm the “flattering " effect of water accumulation as snow and subsequent liquefaction of the infiltration of water into the soil and underground storage. Finally various climate scenarios (+1ºC; +3ºC; +1ºC y – 10% precipitation; y 3ºC – 10% precipitation) were established consistent with IPCC projections for mid - to late - century, determined through simulation ASTER corresponding values of melting. The correlation established on an annual scale has allowed to evaluate the effect of decreasing the volume of melt - in different scenarios - on recharge, predicting a decline in low flows and the disappearance of "snow effect" on infiltration and recharge with an increase of 3°C temperature. Given the conditions of representativeness of the chosen area, plausible extension of the above findings to other landlocked headwaters in mid-mountain areas located between 1000 to 2000m and its downstream effects.

Novel educational assessment for building structures: Automatic evaluation of on-line graphics

This article presents a new automatic evaluation for on-line graphics, its application and the numerous advantages achieved applying this developed correcting method. The software application developed by the Innovation in Education Group “E4”, from the Technical University of Madrid, is oriented for the online self-assessment of the graphic drawings that students carry out as continuous training. The adaptation to the European Higher Educational Area is an important opportunity to research about the possibilities of on-line education assessment. In this way, a new software tool has been developed for continuous self-testing by undergraduates. Using this software it is possible to evaluate the graphical answer of the students. Thus, the drawings made on-line by students are automatically corrected according to the geometry (straight lines, sloping lines or second order curves) and by sizes (depending on the specific values which define the graphics).

Impact of automatic meetering infrastructure on multiutility business models

In the last decade energy utility sector has undergone major changes in terms of liberalization, increased competition, efforts in improving energy efficiency, and in new technological solution such as smart meter and grid operations. There are new information technology solutions (e.g. Advanced Metering Infrastructure /AMI ) on the horizon that will not only introduce new technical and organizational concepts, but have a very strong potential to radically change modus operandi of utility companies. Coordinated, multi-utility programs can help accelerate the development and market success of new high-efficiency technologies. These programs provide opportunities for researchers to develop new high-efficiency equipment for manufacturers to sell this new equipment with utility help, for utilities to increase the amount of energy they save from incentive programs, and for consumers to benefit from lower utility bills and a cleaner environment (as energy is reduced, pollutants produced at power plants decline).

A tool for the automatic analysis of single events effects on electronic circuits

Nowadays integrated circuit reliability is challenged by both variability and working conditions. Environmental radiation has become a major issue when ensuring the circuit correct behavior. The required radiation and later analysis performed to the circuit boards is both fund and time expensive. The lack of tools which support pre-manufacturing radiation hardness analysis hinders circuit designers tasks. This paper describes an extensively customizable simulation tool for the characterization of radiation effects on electronic systems. The proposed tool can produce an in depth analysis of a complete circuit in almost any kind of radiation environment in affordable computation times.

Automatic fault detection on BIPV systems without solar irradiation data

BIPV systems are small PV generation units spread out over the territory, and whose characteristics are very diverse. This makes difficult a cost-effective procedure for monitoring, fault detection, performance analyses, operation and maintenance. As a result, many problems affecting BIPV systems go undetected. In order to carry out effective automatic fault detection procedures, we need a performance indicator that is reliable and that can be applied on many PV systems at a very low cost. The existing approaches for analyzing the performance of PV systems are often based on the Performance Ratio (PR), whose accuracy depends on good solar irradiation data, which in turn can be very difficult to obtain or cost-prohibitive for the BIPV owner. We present an alternative fault detection procedure based on a performance indicator that can be constructed on the sole basis of the energy production data measured at the BIPV systems. This procedure does not require the input of operating conditions data, such as solar irradiation, air temperature, or wind speed. The performance indicator, called Performance to Peers (P2P), is constructed from spatial and temporal correlations between the energy output of neighboring and similar PV systems. This method was developed from the analysis of the energy production data of approximately 10,000 BIPV systems located in Europe. The results of our procedure are illustrated on the hourly, daily and monthly data monitored during one year at one BIPV system located in the South of Belgium. Our results confirm that it is possible to carry out automatic fault detection procedures without solar irradiation data. P2P proves to be more stable than PR most of the time, and thus constitutes a more reliable performance indicator for fault detection procedures. We also discuss the main limitations of this novel methodology, and we suggest several future lines of research that seem promising to improve on these procedures.

Joint 4-D variational stereo reconstruction and camera calibration refinement for oceanic sea state measurements

Validating modern oceanographic theories using models produced through stereo computer vision principles has recently emerged. Space-time (4-D) models of the ocean surface may be generated by stacking a series of 3-D reconstructions independently generated for each time instant or, in a more robust manner, by simultaneously processing several snapshots coherently in a true ?4-D reconstruction.? However, the accuracy of these computer-vision-generated models is subject to the estimations of camera parameters, which may be corrupted under the influence of natural factors such as wind and vibrations. Therefore, removing the unpredictable errors of the camera parameters is necessary for an accurate reconstruction. In this paper, we propose a novel algorithm that can jointly perform a 4-D reconstruction as well as correct the camera parameter errors introduced by external factors. The technique is founded upon variational optimization methods to benefit from their numerous advantages: continuity of the estimated surface in space and time, robustness, and accuracy. The performance of the proposed algorithm is tested using synthetic data produced through computer graphics techniques, based on which the errors of the camera parameters arising from natural factors can be simulated.

Automatic physical activity pattern recognition and meal intake modelling in type 1 diabetes for their inclusion in artificial pancreas systems

La diabetes comprende un conjunto de enfermedades metabólicas que se caracterizan por concentraciones de glucosa en sangre anormalmente altas. En el caso de la diabetes tipo 1 (T1D, por sus siglas en inglés), esta situación es debida a una ausencia total de secreción endógena de insulina, lo que impide a la mayoría de tejidos usar la glucosa. En tales circunstancias, se hace necesario el suministro exógeno de insulina para preservar la vida del paciente; no obstante, siempre con la precaución de evitar caídas agudas de la glucemia por debajo de los niveles recomendados de seguridad. Además de la administración de insulina, las ingestas y la actividad física son factores fundamentales que influyen en la homeostasis de la glucosa. En consecuencia, una gestión apropiada de la T1D debería incorporar estos dos fenómenos fisiológicos, en base a una identificación y un modelado apropiado de los mismos y de sus sorrespondientes efectos en el balance glucosa-insulina. En particular, los sistemas de páncreas artificial –ideados para llevar a cabo un control automático de los niveles de glucemia del paciente– podrían beneficiarse de la integración de esta clase de información. La primera parte de esta tesis doctoral cubre la caracterización del efecto agudo de la actividad física en los perfiles de glucosa. Con este objetivo se ha llevado a cabo una revisión sistemática de la literatura y meta-análisis que determinen las respuestas ante varias modalidades de ejercicio para pacientes con T1D, abordando esta caracterización mediante unas magnitudes que cuantifican las tasas de cambio en la glucemia a lo largo del tiempo. Por otro lado, una identificación fiable de los periodos con actividad física es un requisito imprescindible para poder proveer de esa información a los sistemas de páncreas artificial en condiciones libres y ambulatorias. Por esta razón, la segunda parte de esta tesis está enfocada a la propuesta y evaluación de un sistema automático diseñado para reconocer periodos de actividad física, clasificando su nivel de intensidad (ligera, moderada o vigorosa); así como, en el caso de periodos vigorosos, identificando también la modalidad de ejercicio (aeróbica, mixta o de fuerza). En este sentido, ambos aspectos tienen una influencia específica en el mecanismo metabólico que suministra la energía para llevar a cabo el ejercicio y, por tanto, en las respuestas glucémicas en T1D. En este trabajo se aplican varias combinaciones de técnicas de aprendizaje máquina y reconocimiento de patrones sobre la fusión multimodal de señales de acelerometría y ritmo cardíaco, las cuales describen tanto aspectos mecánicos del movimiento como la respuesta fisiológica del sistema cardiovascular ante el ejercicio. Después del reconocimiento de patrones se incorpora también un módulo de filtrado temporal para sacar partido a la considerable coherencia temporal presente en los datos, una redundancia que se origina en el hecho de que en la práctica, las tendencias en cuanto a actividad física suelen mantenerse estables a lo largo de cierto tiempo, sin fluctuaciones rápidas y repetitivas. El tercer bloque de esta tesis doctoral aborda el tema de las ingestas en el ámbito de la T1D. En concreto, se propone una serie de modelos compartimentales y se evalúan éstos en función de su capacidad para describir matemáticamente el efecto remoto de las concetraciones plasmáticas de insulina exógena sobre las tasas de eleiminación de la glucosa atribuible a la ingesta; un aspecto hasta ahora no incorporado en los principales modelos de paciente para T1D existentes en la literatura. Los datos aquí utilizados se obtuvieron gracias a un experimento realizado por el Institute of Metabolic Science (Universidad de Cambridge, Reino Unido) con 16 pacientes jóvenes. En el experimento, de tipo ‘clamp’ con objetivo variable, se replicaron los perfiles individuales de glucosa, según lo observado durante una visita preliminar tras la ingesta de una cena con o bien alta carga glucémica, o bien baja. Los seis modelos mecanísticos evaluados constaban de: a) submodelos de doble compartimento para las masas de trazadores de glucosa, b) un submodelo de único compartimento para reflejar el efecto remoto de la insulina, c) dos tipos de activación de este mismo efecto remoto (bien lineal, bien con un punto de corte), y d) diversas condiciones iniciales. ABSTRACT Diabetes encompasses a series of metabolic diseases characterized by abnormally high blood glucose concentrations. In the case of type 1 diabetes (T1D), this situation is caused by a total absence of endogenous insulin secretion, which impedes the use of glucose by most tissues. In these circumstances, exogenous insulin supplies are necessary to maintain patient’s life; although caution is always needed to avoid acute decays in glycaemia below safe levels. In addition to insulin administrations, meal intakes and physical activity are fundamental factors influencing glucose homoeostasis. Consequently, a successful management of T1D should incorporate these two physiological phenomena, based on an appropriate identification and modelling of these events and their corresponding effect on the glucose-insulin balance. In particular, artificial pancreas systems –designed to perform an automated control of patient’s glycaemia levels– may benefit from the integration of this type of information. The first part of this PhD thesis covers the characterization of the acute effect of physical activity on glucose profiles. With this aim, a systematic review of literature and metaanalyses are conduced to determine responses to various exercise modalities in patients with T1D, assessed via rates-of-change magnitudes to quantify temporal variations in glycaemia. On the other hand, a reliable identification of physical activity periods is an essential prerequisite to feed artificial pancreas systems with information concerning exercise in ambulatory, free-living conditions. For this reason, the second part of this thesis focuses on the proposal and evaluation of an automatic system devised to recognize physical activity, classifying its intensity level (light, moderate or vigorous) and for vigorous periods, identifying also its exercise modality (aerobic, mixed or resistance); since both aspects have a distinctive influence on the predominant metabolic pathway involved in fuelling exercise, and therefore, in the glycaemic responses in T1D. Various combinations of machine learning and pattern recognition techniques are applied on the fusion of multi-modal signal sources, namely: accelerometry and heart rate measurements, which describe both mechanical aspects of movement and the physiological response of the cardiovascular system to exercise. An additional temporal filtering module is incorporated after recognition in order to exploit the considerable temporal coherence (i.e. redundancy) present in data, which stems from the fact that in practice, physical activity trends are often maintained stable along time, instead of fluctuating rapid and repeatedly. The third block of this PhD thesis addresses meal intakes in the context of T1D. In particular, a number of compartmental models are proposed and compared in terms of their ability to describe mathematically the remote effect of exogenous plasma insulin concentrations on the disposal rates of meal-attributable glucose, an aspect which had not yet been incorporated to the prevailing T1D patient models in literature. Data were acquired in an experiment conduced at the Institute of Metabolic Science (University of Cambridge, UK) on 16 young patients. A variable-target glucose clamp replicated their individual glucose profiles, observed during a preliminary visit after ingesting either a high glycaemic-load or a low glycaemic-load evening meal. The six mechanistic models under evaluation here comprised: a) two-compartmental submodels for glucose tracer masses, b) a single-compartmental submodel for insulin’s remote effect, c) two types of activations for this remote effect (either linear or with a ‘cut-off’ point), and d) diverse forms of initial conditions.

Architecture to Support Automatic Grading Processes in Programming Teaching

La calificación automática de tareas de programación es un tema importante dentro del campo de la innovación educativa que se enfoca en mejorar las habilidades de programación de los estudiantes y en optimizar el tiempo que el profesorado dedica a ello. Uno de los principales problemas vigentes está relacionado con la diversidad de criterios para calificar las tareas de programación. El presente trabajo propone e implementa una arquitectura, basada en el concepto de orquestación de servicios, para soportar varios procesos de calificación automática de tareas de programación. Esto es obtenido a través de las características de modularidad, extensibilidad y flexibilidad que la arquitectura provee al proceso de calificación. La arquitectura define como pieza clave un elemento llamado Grading-submodule, el mismo que provee un servicio de evaluación del código fuente considerando un criterio de calificación. La implementación se ha llevado a cabo sobre la herramienta Virtual Programming Lab; y los resultados demuestran la factibilidad de realización, y la utilidad tanto para el profesorado como para los estudiantes.