COMPARACIÓN DEL GRADIENTE DE TEMPERATURA EN ESPACIOS CÚBICOS CONTROLADOS CON CELDA PELTIER EN FUNCIÓN A DOS AISLANTES TÉRMICOS. (COMPARISON OF THE TEMPERATURE GRADIENT IN CUBIC SPACES CONTROLLED WITH PELTIER CELL ACCORDING TO TWO THERMAL INSULATORS.)

ResumenEste trabajo estudia el gradiente de temperatura en espacios cúbicos de dimensiones pequeñas utilizando dispositivos de enfriamiento peltier. Se demuestra que el material, el volumen, potencia y temperatura exterior afecta la eficiencia de un elemento termoeléctrico.  Los materiales seleccionados en la construcción de los espacios cúbicos cuentan con baja conductividad térmica, a fin de evitar que la temperatura exterior afecte a la medición. Se tomaron periódicamente valores de temperatura en espacios cúbicos. El banco de prueba consiste en microcontrolador, disipadores de calor en lado frio y caliente y módulos peltier. Se realizó la comparación de los valores que obtienen en cada volumen. Se determina el uso de mayor cantidad de celdas peltier, optimizando el tiempo de enfriamiento y la potencia necesaria que se requiera. Según las ecuaciones que se obtienen el comportamiento del enfriamiento en espacios cúbicos es semejante, la eficiencia que se presenta en enfriamiento a espacios es reflejada en material, volumen, potencia de enfriamiento y temperatura externa. Palabras Claves: Peltier, Modelado, temperatura, Gradiente, Optoelectrónica.AbstractThis paper studies the temperature gradient in cubic spaces of small dimensions using peltier cooling devices. The dependency of the material, volume, power and external temperature was studied, which it affects the efficiency of a thermoelectric element. The materials selected for the cubic spaces elaboration were chosen with low thermal conductivity, since this avoid the room temperature affecting the measurement. The internal temperature of the cubic spaces was taken at periodic    intervals to observe its behavior. The characterization was carried out using a microcontroller, heat sinks on cold and hot sides, and peltier modules. The temperature was compared between each volume used to obtain an optimization as a function of peltiers cells, in a minimal time of set point of cooling temperature and the power required. The equiation obtain in According to the equations that are obtained the behavior of movement in cubic spaces is similar, the efficiency that is presented in space limitations is reflected in material, volume, cooling power and external temperature.Keywords: Peltier, Modeling, Temperature, Gradient, Optoelectronics

CARACTERIZACIÓN DE UN INCLINÓMETRO ÓPTICO PARA DESPLAZAMIENTO VERTICAL DE ESTRUCTURAS CIVILES (CHARACTERIZATION OF AN OPTICAL INCLINOMETER FOR VERTICAL DISPLACEMENT OF CIVIL STRUCTURES)

ResumenEn este artículo, se presenta un sensor de inclinación de fibra óptica basado en la modulación de intensidad, la cual se relaciona experimentalmente en función de pérdidas provocadas por macrocurvaturas en una fibra multimodo. El inclinómetro utiliza un engrane-cremallera, que cuando el eje principal del mecanismo sufre una inclinación, se modifica la trayectoria de la luz debido al cambio de curvatura en la fibra óptica. Para la caracterización del sensor se empleó una fuente de luz y un medidor de intensidad para pruebas de laboratorio. Se observó en la configuración experimental propuesta, que a mayor ángulo de inclinación mayor pérdida de intensidad óptica experimenta. Los resultados experimentales mostraron que el inclinómetro proporcionaba un rango de medición de 0 ° a 10° con una sensibilidad de 0.232 nW/°.Palabras Claves: Fibra multimodo, inclinómetro, macrocurvatura. AbstractIn this article, an optical fiber inclination sensor based on intensity modulation is presented, which is experimentally related to losses caused by macrocurvatures in a multimode fiber. The inclinometer uses a gear-rack, which when the main axis of the mechanism suffers an inclination, the light path is modified due to the change in curvature in the optical fiber. For the characterization of the sensor, a light source and an intensity meter were used for laboratory tests. It was observed in the proposed experimental configuration, that the greater the inclination angle the greater the loss of optical intensity it experiences. Experimental results showed that the inclinometer provided a measuring range of 0 ° to 10 ° with a sensitivity of 0.232 nW/°.Keywords: Inclinometer, macro-curvature, multimode fiber

FPGA-based smart camera for accurate chlorophyll estimations

International audienceIn this work, a new chlorophyll estimation approach based on the reflectance/trans-mittance from the leaf being analyzed is proposed. First, top/underside images from the leaf under analysis are captured, then, the base parameters (reflectance/trans-mittance) are extracted. Finally, a double-variable linear regression model estimates the chlorophyll content. In order to estimate the base parameters, a novel optical arrangement is presented. On the other hand, in order to provide a portable device, suitable for chlorophyll estimation under large scale food crops, we have implemented our optical arrangement and our algorithmic formulation inside an FPGA-based smart camera fabric. Experimental results demonstrated that the proposed approach outperforms (in terms of accuracy and processing speed) most previous vision-based approaches, reaching more than 97% accuracy and delivering fast chlorophyll estimations (near 5ms per estimation)

Robust sensor fault estimation for descriptor-LPV systems with unmeasurable gain scheduling functions: Application to an anaerobic bioreactor

This paper addresses the design of a state estimation and sensor fault detection, isolation and fault estimation observer for descriptor-linear parameter varying (D-LPV) systems. In contrast to where the scheduling functions depend on some measurable time varying state, the proposed method considers the scheduling function depending on an unmeasurable state vector. In order to isolate, detect and estimate sensor faults, an augmented system is constructed by considering faults to be auxiliary state vectors. An unknown input LPV observer is designed to estimate simultaneously system states and faults. Sufficient conditions to guarantee stability and robustness against the uncertainty provided by the unmeasurable scheduling functions and the influence of disturbances are synthesized via a linear matrix inequality (LMI) formulation by considering H∞ and Lyapunov approaches. The performances of the proposed method are illustrated through the application to an anaerobic bioreactor model

An FPGA Correlation-Edge Distance approach for disparity map

International audience—This paper describes an FPGA Correlation-Edge Distance approach for real time disparity map generation in stereo-vision. The proposed method calculates the disparity map for the input and disparity map for Edge Distance images of a stereopair. In both cases the approximation algorithm of disparity map SAD (Sum of Absolute Differences) is used. The final disparity map is determined from the previously generated maps, considering a homogeneity parameter defined for each point in the scene. Due to low complexity when implementing stereo-vision algorithms in FPGA devices, the proposed method was implemented in a Cyclone II EP2C35F672C6 FPGA assembled in an Altera DE2 breadboard. The developed module can process stereo-pairs of 1280×1024 pixel resolution at a rate of 75 frames/s and produces 8-bit dense disparity maps within a range of disparities up to 63 pixels. The presented architecture provides a significant improvement in regions with uniformed texture over correlation based stereo-vision algorithms in the reported literature and an accelerated processing rate