155 research outputs found
Modelos de elementos finitos de componentes de autobuses fabricados en materiales compuestos
La creciente preocupación por la seguridad en el transporte de pasajeros, ha hecho que las estructuras de los autobuses y autocares se vean sometidas a solicitaciones cada vez más exigentes, sobre todo ante condiciones de vuelco cuyos requerimientos vienen determinados por el Reglamento 66 de ginebra. Es por eso que en esta ponencia se pretende presentar una alternativa de pilares de estructura con materiales compuestos para el uso de los mismos como método reductor de masa de los vehículos. Para ello se presentan ensayos a flexión de pilares y modelos de cálculos validados con dichos ensayos
Passive Safety of Children Carriages on Busses
The safe mobility of young children traveling with carriages in public transportation vehicles is a problem that has not yet been satisfactorily resolved. The lack of national and international standards in this area in the past led to the development of a research developed jointly by the Universitat Politécnica Valencia and the Universidad Politécnica Madrid (Spain). This book chapter shows the results of a research program developed to evaluate the dynamic behavior of occupied children carriages (ChC) during typical driving maneuvering—sudden braking, acceleration and cornering—and in case of low-g accidents reproducing frontal impacts resembling real traffic events (deceleration 2 g, ΔV 20 km/h). In the dynamic trials, three ChC-restraint prototypes and a typical wheelchair (WhCh) back-restraint system combined with two representatives of up-to-date ChC models in misuse and correct use configurations were tested. The results demonstrated the need for preventing children injuries as a consequence of low-g accidents.A Code of Good Practice was proposed jointly with the use of a new ChC-restraint system considering R 107–06 series of amendments. The new design improves the latest revision of regulation R107 regarding the use of back-restraint systems for the transport of WhCh and ChC passengers traveling on busses
Experimental protocol to assess the tourism vehicles accessibility based on heart rate and access time measurements
[EN] The objective of the Project is to define an experimental protocol for the accessibility assessment of the transport vehicles, by analysing the evolution of the effort and time variables consumed by a target group –Persons of Reduced Mobility (PMRs). This protocol consisted in tests of accessibility on a sample of 6 passenger cars (class M1) by 8 elderly people carrying a heart rate monitor, and whose access manoeuvres were recorded by video cameras. Based on the Hilloskorpi et al. [1] model and by developing a method of truncation of the heart rate (HR) tests records - eliminating the component of the work biologically needed by the organism to keep its basal metabolic rate from the work each person performed – it was possible to evaluate how much energy each individual invested in each access manoeuver. Immediately after each test, and after the whole round of vehicles, each participant was surveyed for a subjective assessment of the difficulty of accessing to the cars. According to each of the above results, the HR objective measurements and the subjective opinion about the ease of access experienced by each individual, the vehicles were ranked by order of accessibility to the front and rear seats. The result of both rankings showed the orders of the similar vehicles, the potential of the method and a fair closeness between its results and the subjective, but real and unequivocal, judgments of the participants.This article is based on the Project "Desarrollo de un protocolo experimental de evaluación
de la accesibilidad a los vehículos turismo en base a mediciones de frecuencia cardíaca y
tiempo de acceso", October 2015 in Madrid, Spain.Alcalá Fazio, E.; Alvarez Fernández, N. (2016). Experimental protocol to assess the tourism vehicles accessibility based on heart rate and access time measurements. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 2511-2518. https://doi.org/10.4995/CIT2016.2016.3501OCS2511251
Córdoba taurina : apuntes biográficos de matadores, banderilleros, picadores, puntilleros, maletas, ganaderos, propietarios de plazas, empresarios, aficionados, revisteros y escritores taurinos antig..uos y modernos
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2011Del texto se deduce impreso con posterioridad a 189
Optimización de las superestructuras de autobuses y autocares sometidos al vuelco lateral
En la presente tesis, como en todo proceso de optimization, se ha llevado a cabo un análisis previo de los factores determinantes del problema. Para ello, en primer lugar, se ha puesto a punto un proceso teórico-experimental de verificación de la resistencia de las superestructuras de autobuses y autocares sometidas a vuelco lateral. A partir de la definición de dicho proceso, se ha utilizado el mismo para obtener determinados criterios de diseño que permitan mejorar la relación resistencia/peso de cada estructura. Por último, en base a la experiencia adquirida en la elaboración del proceso de verificación, se han planteado posibles enmiendas y aclaraciones que debieran reflejarse en el Reglamento 66. Este desarrollo ha permitido extraer conclusiones relativas a cada uno de los tres aspectos mencionados: proceso de verificación, criterios de diseño y posibles enmiendas, o rectificaciones, aplicables al Rgt
Diseño y desarrollo experimental de sistemas y dispositivos electrónicos para el apoyo a la criopreservación mediante equilibrio termodinámico de órganos
Mediante el presente proyecto se desarrollan sistemas de apoyo a la criopreservación de órganos de mus musculus a partir de la técnica equilibrium vitrification aplicada a diferentes tejidos desde un acercamiento experimental.
La tarea en cuestión comporta el diseño y cálculo de una serie de sistemas electrónicos, térmicos, hidráulicos y químicos, extendiéndose por numerosas ramas de la ingeniería y las ciencias. Para ello, se establece como objetivo principal la perfusión con crioprotector de corazón y encéfalo de ratón y la supervivencia del órgano hasta este instante de perfusión. La técnica de vitrificación por equilibrio requiere, en concreto, el seguimiento de unas curvas de concentración de crioprotector y de temperatura para una serie de instantes de tiempo, y esto se hubo de aplicar a ambos órganos.
Se realizaron pues tres experimentos (con diversos ensayos para cada uno de ellos) para la correcta criopreservación de los tejidos, a saber: la supervivencia ex-vivo del corazón en un medio artificial mediante sistemas térmicos, electrónicos e hidráulicos, la perfusión del corazón aislado siguiendo las curvas propias de la técnica, y la perfusión del encéfalo o tejido nervioso central, no aislado, siguiendo las anteriores curvas. Esto se consigue con sistemas hidráulicos, electrónicos, químicos y térmicos.
A lo largo de la fase experimental se comprobó la mejora de la supervivencia de los órganos aislados (corazones) gracias al ajuste de los parámetros tales como el caudal y presión de perfusión, obedeciendo las condiciones de contorno impuestas por los propios sistemas biológicos. Se obtuvo igualmente una mejora en la perfusión y en la retención de agente crioprotector conforme se mejoraba la supervivencia de dichos órganos. En lo referente a corazón, se alcanzaron los valores de concentración deseados y marcados por las curvas de vitrificación de equilibrio, así como la temperatura a la cual se alcanzaban los valores deseados. En el caso del encéfalo, se obtuvieron valores menores a los del corazón dada la estructura tisular y el comportamiento de los elementos hidrosolubles con la pared celular del tejido nervioso.Through the present project, the development of support systems for murine organ cryopreservation using the equilibrium vitrification technique applied to different tissues is presented. This involves an experimental approach to the problem.
The task comprises the design and calculation of several electronic, thermal, hydraulic and chemical systems. For this matter, the main objective was established: whole organ perfusion with cryoprotectant, for both murine heart and encephala, and the survival of said organ up to the initiation of perfusion. The equilibrium vitrification technique requires, specifically, following certain concentration and temperature curves for given instants in time, and this had to be applied to both organs.
Hence three experiments took place (with several repetitions for each one of them) to correctly cryopreserve the tissues: ex-vivo survival of the murine heart in an artificial environment thanks to electronic, thermal and hydraulic systems following the previously stated curves, and the correct perfusion of central nerve system or encephala, in-vivo, following the curves, which requires chemical, hydraulic, electronic and thermal systems and their control.
Throughout the experimental phase it was proven the survival of the isolated heart provided the correct adjustment of flow and pressure parameters, subject to the conditions imposed by the biological systems. Likewise, it was observed an improvement in the perfusion and retention of the cryoprotecting agent according to the improvement of organ survival up to this phase. Regarding to the heart, the desired ACP values were reached as given by the concentration curves for equilibrium vitrification, as well as the temperatures reached within the time specifications. Regarding encephala, lower values were reached due to the tissue structure and behavior of hydrosoluble reactants given the nervous tissue wall structure.Universidad de Sevilla. Grado en Electrónica, Robótica y Mecatrónic
THEORETICAL-EXPERIMENTAL ASSESMENT OF BRAKING SISTEMS FOR INCLINED LIFTS ACCORDING TO EN 81:22-2014
[EN] The inclined lifts, in case of emergency braking, can experience high longitudinal decelerations that can lead to passengers’ collisions with lift walls and interior elements. In 2014 the CEN/TC10 WG1 published the part 22 of the norm series 81 with regard to the construction elements and installation of electrical lifts with inclined trajectory. This norm stablishes, amongst other requirements, the maximum and minimum deceleration levels in both longitudinal and vertical directions. Both requirements, in opposite senses and the definition of the braking system, do not cause design difficulties in case of high slopes, but in case of lifts with the slope under a certain level they can be needed, to guarantee the fulfilment of the norm, elements that allow and additional relative displacement between the braking system and the cabin. To define the performances and the optimal behaviour of these systems it has been defined a simulation model of the dynamical behaviour of the lift under the conditions of the norm tests. Additionally, in this work it is presented a calculation methodology to define the cabin allowable weight corridor, for each braking effort made by each safety gear model, and the simulations have been validated with the results of tests with different braking efforts, weights and lift slopes. The present work has been performed in cooperation with Thyssen Krupp Elevadores with the aim of improving the knowledge of the brake dynamics of inclined lifts.Valles Fernandez, B.; Martin López, AL.; Alcalá, E. (2016). THEORETICAL-EXPERIMENTAL ASSESMENT OF BRAKING SISTEMS FOR INCLINED LIFTS ACCORDING TO EN 81:22-2014. En XII Congreso de ingeniería del transporte. 7, 8 y 9 de Junio, Valencia (España). Editorial Universitat Politècnica de València. 2538-2548. https://doi.org/10.4995/CIT2016.2016.2173OCS2538254
Metodología para la medida de la energía consumida en las maniobras de acceso y salida de turismos empleando el sistema de captura de movimiento Kinect
El proyecto que se describe en este artículo pretende desarrollar una metodología que permita medir el gasto energético cuando una persona entra y sale de un vehículo. Para la captura de las maniobras que realiza la persona se emplea la especificación más reciente del sistema de captura de movimiento Kinect. La medida del gasto energético se plantea como una forma de evaluar la accesibilidad a las plazas de un vehículo y está especialmente orientado a personas mayores y personas con movilidad reducida en general. En primer lugar se evalúa la capacidad del sistema de captura de movimiento Kinect en lo referente a precisión en el seguimiento de las diferentes articulaciones del cuerpo que incorpora el modelo tanto en escenarios despejados como en presencia de obstáculos visuales. A continuación, su capacidad para captar las maniobras que se realizan para entrar al habitáculo y subsanar los problemas que plantea el trabajar con un habitáculo de dimensiones más o menos reducidas y con elementos de morfologías diversas como los asientos y el salpicadero. En paralelo, se trabaja en una metodología que permita obtener información sobre el gasto energético de una persona a la hora de realizar las maniobras de acceso y salida que se capturen. La unión de la valoración energética del movimiento y de la captura del mismo con la fiabilidad necesaria debe confluir en la metodología para valorar energéticamente la accesibilidad de un turismo
Theoretical-experimental assessment of braking systems for inclined lifts according to EN 81:22-2014
The inclined lifts, in case of emergency braking, can experience high longitudinal decelerations that can lead to passengers’ collisions with lift walls and interior elements. In 2014 the CEN/TC10 WG1 published the part 22 of the norm series 81 with regard to the construction elements and installation of electrical lifts with inclined trajectory. This norm stablishes, amongst other requirements, the maximum and minimum deceleration levels in both longitudinal and vertical directions. Both requirements, in opposite senses and the definition of the braking system, do not cause design difficulties in case of high slopes, but in case of lifts with the slope under a certain level they can be needed, to guarantee the fulfilment of the norm, elements that allow and additional relative displacement between the braking system and the cabin. To define the performances and the optimal behaviour of these systems it has been defined a simulation model of the dynamical behaviour of the lift under the conditions of the norm tests. Additionally, in this work it is presented a calculation methodology to define the cabin allowable weight corridor, for each braking effort made by each safety gear model, and the simulations have been validated with the results of tests with different braking efforts, weights and lift slopes. The present work has been performed in cooperation with Thyssen Krupp Elevadores with the aim of improving the knowledge of the brake dynamics of inclined lifts
Coherent carrier dynamics in semiconductor superlattices
We investigate the coherent dynamics of carriers in semiconductor
superlattices driven by ac-dc electric fields. We solve numerically the
time-dependent effective-mass equation for the envelope function. We find that
carriers undergo Rabi oscillations when the driving frequency is close to the
separation between minibands.Comment: REVTEX (6 pages) and 3 figures (PostScript). Accepted in Physics
Letters
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