Análisis Biomecánico Bidimensional

Uno de los objetivos de la biomecánica deportiva es el análisis de la técnica deportiva en 3D. Para ello, se utilizan principalmente sistemas de fotogrametría video basados, en la mayoría de los casos, en el algoritmo conocido como DLT (Direct Linear Transformation). Este procedimiento ha demostrado ser muy preciso y fácil de implementar por lo que ha sido utilizado masivamente en el Análisis Biomecánico. En algunas ocasiones, el tipo de movimiento y los requerimientos del trabajo hacen que el investigador esté interesado exclusivamente en el movimiento en el plano. En estos casos el principal objetivo suele ser el estudio de las variables cinemáticas (posiciones, distancias, velocidades, aceleraciones) solo en dos de las tres dimensiones del espacio. Existen tres situaciones claramente diferenciadas donde es factible aplicar un Análisis Biomecánico Bidimensional: 1) Cuando se analiza la técnica deportiva en movimientos desarrollados principalmente en un plano como un salto de longitud, la carrera, el pedaleo, etc. 2) cuando se investiga sobre deportes cíclicos y 3) cuando se estudia el movimiento en deportes de equipo. A continuación mostraremos estos los tres tipos de Análisis Biomecánico Bidimensional, describiendo en primer lugar la metodología utilizada y a continuación presentando los resultados de algún estudio real ya publicado

The Validity and Reliability of a Procedure for Competition Analysis in Swimming Based on Individual Distance Measurements

In swimming, competition analyses have been frequently performed according to three segments of the nee, equal for all competitors. However, individual distance measurements during start and turn race segments have been scarcely assessed. The aim of the present study was: 1) to verify the validity and reliability of a 2D-DLT based system for competition analysis in swimming and, 2) to compare it with die commonly used technique. Higher values of accuracy (RMSE=0.05 m) and reliability (CV<1%) were obtained 95% Limits of agreement revealed differences no longer than one frame (0.04 s) between the two compared procedures. The results showed that the 2D-DLT procedures ire valid tor competition analysis in swimming and that the differences between 2D-DLT and scaling technique are acceptabl

Biomechanical analysis of the 10km-run in a triathlon world cup event: differences presented by women gold meda

In most of the triathlon races, the 10km-run is critical to win and, just a few seconds, may separate the gold and the silver medal. To our best knowledge, no study has analyzed the biomechanical differences among the first qualified triathletes during a top-level competition. The aims of the present study were: (1) to examine the different responses to the previous cycling between the gold medal and the other participants, and (2) to compare the biomechanical profiles during the 10km-run presented by the top-ranked triathletes. 16 women, participants at Madrid 2008 Triathlon World Cup, were analyzed. The first qualified triathlete (gold medal) showed significant differences (p < 0.05) with the other participants in many of the analyzed variables. A higher stride length, a smaller stride frequency, a higher and more consistent horizontal distance hip- toe cap and a more extended knee angle of the support-leg at toe-off could explain the differences in 10km-run time between gold medal and the other participant

Pixel Features for Self-organizing Map Based Detection of Foreground Objects in Dynamic Environments

Among current foreground detection algorithms for video sequences, methods based on self-organizing maps are obtaining a greater relevance. In this work we propose a probabilistic self-organising map based model, which uses a uniform distribution to represent the foreground. A suitable set of characteristic pixel features is chosen to train the probabilistic model. Our approach has been compared to some competing methods on a test set of benchmark videos, with favorable results.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Super-resolution of 3D Magnetic Resonance Images by Random Shifting and Convolutional Neural Networks

Enhancing resolution is a permanent goal in magnetic resonance (MR) imaging, in order to keep improving diagnostic capability and registration methods. Super-resolution (SR) techniques are applied at the postprocessing stage, and their use and development have progressively increased during the last years. In particular, example-based methods have been mostly proposed in recent state-of-the-art works. In this paper, a combination of a deep-learning SR system and a random shifting technique to improve the quality of MR images is proposed, implemented and tested. The model was compared to four competitors: cubic spline interpolation, non-local means upsampling, low-rank total variation and a three-dimensional convolutional neural network trained with patches of HR brain images (SRCNN3D). The newly proposed method showed better results in Peak Signal-to-Noise Ratio, Structural Similarity index, and Bhattacharyya coefficient. Computation times were at the same level as those of these up-to-date methods. When applied to downsampled MR structural T1 images, the new method also yielded better qualitative results, both in the restored images and in the images of residuals.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

HCFC-22 replacement with drop-in and retrofit HFC refrigerants in a two-stage refrigeration plant for low temperature

[EN] The world community has committed to eliminate the HCFC-22 refrigerant to a series of deadlines according to the agreements taken during the 19th Montreal Protocol meeting in September 2007. This phase-out, which is already in progress in European Countries, has been accelerated in Article 5 countries. Refrigerant manufactures offer different drop-in refrigerants to replace R22 in existing equipment by non-ozone depleting substances in order to be able to make full use of the remaining life of the plants or different retrofit refrigerants, the use of which implies modifications to the existing systems. This work aims to contribute to the understanding of the implications of the process of R22 substitution, either with drop-in or retrofitting processes, by presenting a theoretical and experimental analysis of the performance of R22, of two drop-in fluids (R422A, R417B) and a retrofit refrigerant (R404A), in a two-stage vapour compression plant over a wide range of evaporating temperatures for a fixed condensing temperature of 40 C. In this communication the main energy parameters, such as cooling capacity and COP are analysed and discussed.The authors are indebted to the Spanish Ministry of Education and Science (CTM2008-06468-CO2-02/TECNO) and to the Spanish Ministry of the Environment and Rural and Marine Affairs (200800050084716) for their economic support for the present work.Llopis, R.; Torrella Alcaraz, E.; Cabello, R.; Sanchez, D. (2012). HCFC-22 replacement with drop-in and retrofit HFC refrigerants in a two-stage refrigeration plant for low temperature. International Journal of Refrigeration. 35(4):810-816. https://doi.org/10.1016/j.ijrefrig.2012.01.001S81081635

Bio-Inspired Stereo Vision Calibration for Dynamic Vision Sensors

Many advances have been made in the eld of computer vision. Several recent research trends have focused on mimicking human vision by using a stereo vision system. In multi-camera systems, a calibration process is usually implemented to improve the results accuracy. However, these systems generate a large amount of data to be processed; therefore, a powerful computer is required and, in many cases, this cannot be done in real time. Neuromorphic Engineering attempts to create bio-inspired systems that mimic the information processing that takes place in the human brain. This information is encoded using pulses (or spikes) and the generated systems are much simpler (in computational operations and resources), which allows them to perform similar tasks with much lower power consumption, thus these processes can be developed over specialized hardware with real-time processing. In this work, a bio-inspired stereovision system is presented, where a calibration mechanism for this system is implemented and evaluated using several tests. The result is a novel calibration technique for a neuromorphic stereo vision system, implemented over specialized hardware (FPGA - Field-Programmable Gate Array), which allows obtaining reduced latencies on hardware implementation for stand-alone systems, and working in real time.Ministerio de Economía y Competitividad TEC2016-77785-PMinisterio de Economía y Competitividad TIN2016-80644-

Urban dwelling environments case study: Mexico City

Thesis (M.Arch.A.S.) Massachusetts Institute of Technology. Dept. of Architecture, 1974.Also issued by the M.I.T. Education Research Program: Urban Settlement Design in Developing Countries, Cambridge, Mass. in 1974.Bibliography: p. 180.by Jose Luis Cortes Delgado, Ramiro Marcelo Davila Cabello, Enrique Ignacio Espinosa Fernandez.M.Arch.A.S

Evolución de la longitud de zancada en la prueba de 60 metros vallas

La investigación científica acerca de la longitud de las zancadas en la prueba de vallas altas, tanto en pista cubierta como aire libre, se ha llevado a cabo mediante estudios en dos y tres dimensiones o empleando técnicas similares. Dichos estudios se han desarrollado bien sobre una o dos vallas o analizando el intervalo entre ellas. De este modo, existen referencias sobre la longitud de la zancada en el paso de la segunda valla [3], más frecuentemente sobre la tercera, cuarta o quinta valla [4] y, en ocasiones, analizando la octava o novena valla [2]. En cualquier caso, estos trabajos no han sido realizados sobre todos los deportistas que competían en la serie y, frecuentemente, se han llevado a cabo en condiciones de entrenamiento. Es por ello que el objetivo de la presente investigación fuese conocer cuáles eran los valores en competición a lo largo de toda la prueba en una amplia muestra de atletas, analizando la posible existencia de variaciones en la longitud de zancada entre las vallas

Modificación de mecanismo de extensión de prótesis de rodilla policéntrica

En este proyecto se lleva a cabo la mejora mecánica de una rodilla protésica policéntrica, modelo Total Knee 1900. Uno de los inconvenientes que presenta este modelo es que el mecanismo de ayuda a la extensión está formado por un muelle unido a un cable de acero, que se debe ser sustituido por un técnico ortopeda manualmente si el portador desea variar la velocidad de marcha. El movimiento de extensión de la pierna, que condiciona la velocidad del paso, se produce de forma inercial, similar a un péndulo, con una velocidad máxima (dependiente de su masa y geometría, y en la que interviene, además, la contribución del muelle) que impide al usuario aumentar su ciclo de marcha. Se diseña un mecanismo para sustituir el resorte, mediante el cual sea posible variar la velocidad de marcha según los requerimientos del usuario. El diseño e implementación de este dispositivo, conlleva un análisis y estudio cinemático previo de la pierna ortopédica, implementando un modelo simplificado de cálculo. Una vez obtenidas las velocidades y fuerzas que actúan sobre el mecanismo, se procede a la selección de un actuador eléctrico, que permita variar la fuerza y la velocidad de aplicación de esta, según requisitos. El actuador, somete a tracción el cable de acero presente en la rodilla protésica originalmente, ejerciendo un trabajo similar al muelle, pero con la ventaja de ser regulable. Se diseña todos los elementos necesarios para poder acoplar el actuador seleccionado a la pierna ortopédica, realizando un estudio de esfuerzos para determinar si las piezas propuestas soportan las cargas a las que van a estar solicitadas. Posteriormente, con la finalidad de crear un prototipo, se realiza un proceso de ingeniería inversa, obteniendo un modelo tridimensional de la rodilla.In this project, the mechanical improvement of a polycentric prosthetic knee, model Total Knee 1900, is carried out. One of the drawbacks of this model is that the extension aid mechanism is formed by a spring attached to a steel cable, that it must be replaced, by an orthopedic technician, manually if the wearer wishes to vary the speed. The leg extension movement, which determines the speed of the step, occurs inertially, similar to a double pendulum and has a maximum speed (depending on its mass and geometry). This movement prevents the user from increasing their running cycle and therefore, a mechanism is designed to replace the spring, by means of which it is possible to vary the running speed according to the user's requirements. The design and implementation of this device involves a prior kinematic analysis and study of the orthopedic leg, implementing a simplified calculation model. Once the speeds and forces acting on the mechanism have been obtained, an electric actuator is selected, which allows the force and speed of its application to be varied, according to the requirements. The actuator pulls the steel cable present in the prosthetic knee originally, performing a work similar to the spring, but with the advantage of being adjustable. Next, all the necessary elements are designed to be able to couple the selected actuator to the orthopedic leg, carrying out a stress study to determine if the proposed parts support the loads to which they will be applied. Subsequently, in order to create a prototype, a reverse engineering process is carried out, obtaining a three-dimensional model of the knee