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 implementation of an efficient similarity-based adaptive window algorithm for real-time stereo matching

International audienceThe stereo matching is one of the most widely used algorithms in real-time image processing applications such as positioning systems for mobile robots, three-dimensional building mapping and both recognition, detection and three-dimensional reconstruction of objects. In area-based algorithms, the similarity between one pixel of the left image and one pixel of the right image is measured using a correlation index computed on vicinities of these pixels called correlation windows. In order to preserve edges, small windows need to be used. On the other hand, for homogeneous areas, large windows are required. Due to only local information is used, matching between primitives is difficult. In this article, FPGA implementing of an efficient similarity-based adaptive window algorithm for dense disparity maps estimation in real-time is described. In order to evaluate the proposed algorithm behavior, the developed FPGA architecture was simulated via ModelSim-Altera 6.6c using different synthetic stereo pairs and different sizes for correlation window. In addition, the FPGA architecture was implemented in an FPGA Cyclone IIEP2C35F672C6 embedded in an Altera development board DE2. The disparity maps are computed at a rate of 76 frames per second for stereo pairs of 1280×1024 pixel resolution and a maximum expected disparity equal to 15. The developed FPGA architecture offers better results with respect to the most of real-time area-based stereo matching algorithms reported in the literature, allows increasing the processing speed up to 93,061,120 pixels per second and enables it to be implemented in the majority of the medium-gamma FPGA devices

An FPGA 2D-convolution unit based on the CAPH language

International audienceConvolution is an important operation in image processing applications, such as edge detection, sharpening , adding blurring and so on. Convolving video streams in real-time is a challenging task for PC systems, however, FPGA devices can successfully be used in these tasks. In this article, the design and implementation of a reconfigurable FPGA architecture for 2D-convolution filtering is described. The filtered frames are calculated at a rate of 103 frames per second for images up to 1200×720 pixel resolution. By using a shift-based arithmetic and circular buffers, the developed FPGA architecture allows to reduce the hardware resources consumption up to 98% compared to the conventional convolution implementations , provides high speed processing and enables to manage large number of different convolution kernels. On the other hand, by using the CAPH language it is possible to reduce the design time up to 75% compared to the plain VHDL design. Furthermore, to maintain high flexibility in concordance with the input video, the developed hardware allows to configure the resolution of the input images with values of 3 × Y up to 1200 × Y , and allows scalability for different sizes of convolution kernels of simple and systematic form. Finally , the developed FPGA architecture for the proposed method was implemented and validated in an FPGA Cyclone II EP2C35F672C6 embedded in an Altera development board DE2

Numerical Study of a Solar Cell to Achieve the Highest InGaN Power Conversion Efficiency for the Whole In-Content Range

A solar cell structure with a graded bandgap absorber layer based on InGaN has been proposed to overcome early predicted efficiency. Technological issues such as carrier concentration in the p- and n-type are based on the data available in the literature. The influence of carrier concentration-dependent mobility on the absorber layer has been studied, obtaining considerable improvements in efficiency and photocurrent density. Efficiency over the tandem solar cell theoretical limit has been reached. A current density of 52.95 mA/cm2, with an efficiency of over 85%, is determined for a PiN structure with an InGaN step-graded bandgap absorption layer and 65.44% of power conversion efficiency for the same structure considering piezoelectric polarization of fully-strained layers and interfaces with electron and hole surface recombination velocities of 10−3 cm/s

Optical Method for Estimating the Chlorophyll Contents in Plant Leaves

This work introduces a new vision-based approach for estimating chlorophyll contents in a plant leaf using reflectance and transmittance as base parameters. Images of the top and underside of the leaf are captured. To estimate the base parameters (reflectance/transmittance), a novel optical arrangement is proposed. The chlorophyll content is then estimated by using linear regression where the inputs are the reflectance and transmittance of the leaf. Performance of the proposed method for chlorophyll content estimation was compared with a spectrophotometer and a Soil Plant Analysis Development (SPAD) meter. Chlorophyll content estimation was realized for Lactuca sativa L., Azadirachta indica, Canavalia ensiforme, and Lycopersicon esculentum. Experimental results showed that—in terms of accuracy and processing speed—the proposed algorithm outperformed many of the previous vision-based approach methods that have used SPAD as a reference device. On the other hand, the accuracy reached is 91% for crops such as Azadirachta indica, where the chlorophyll value was obtained using the spectrophotometer. Additionally, it was possible to achieve an estimation of the chlorophyll content in the leaf every 200 ms with a low-cost camera and a simple optical arrangement. This non-destructive method increased accuracy in the chlorophyll content estimation by using an optical arrangement that yielded both the reflectance and transmittance information, while the required hardware is cheap

Lamb Behaviors Analysis Using a Predictive CNN Model and a Single Camera

Object tracking is the process of estimating in time N the location of one or more moving element through an agent (camera, sensor, or other perceptive device). An important application in object tracking is the analysis of animal behavior to estimate their health. Traditionally, experts in the field have performed this task. However, this approach requires a high level of knowledge in the area and sufficient employees to ensure monitoring quality. Another alternative is the application of sensors (inertial and thermal), which provides precise information to the user, such as location and temperature, among other data. Nevertheless, this type of analysis results in high infrastructure costs and constant maintenance. Another option to overcome these problems is to analyze an RGB image to obtain information from animal tracking. This alternative eliminates the reliance on experts and different sensors, yet it adds the challenge of interpreting image ambiguity correctly. Taking into consideration the aforementioned, this article proposes a methodology to analyze lamb behavior from an approach based on a predictive model and deep learning, using a single RGB camera. This method consists of two stages. First, an architecture for lamb tracking was designed and implemented using CNN. Second, a predictive model was designed for the recognition of animal behavior. The results obtained in this research indicate that the proposed methodology is feasible and promising. In this sense, according to the experimental results on the used dataset, the accuracy was 99.85% for detecting lamb activities with YOLOV4, and for the proposed predictive model, a mean accuracy was 83.52% for detecting abnormal states. These results suggest that the proposed methodology can be useful in precision agriculture in order to take preventive actions and to diagnose possible diseases or health problems