Environmental assessment of low speed policies for motor vehicle mobility in city centres

streets in local residential areas in large cities, real traffic tests for pollutant emissions and fuel consumption have been carried out in Madrid city centre. Emission concentration and car activity were simultaneously measured by a Portable Emissions Measurement System. Real life tests carried out at different times and on different days were performed with a turbo-diesel engine light vehicle equipped with an oxidizer catalyst and using different driving styles with a previously trained driver. The results show that by reducing the speed limit from 50 km h-1 to 30 km h-1, using a normal driving style, the time taken for a given trip does not increase, but fuel consumption and NOx, CO and PM emissions are clearly reduced. Therefore, the main conclusion of this work is that reducing the speed limit in some narrow streets in residential and commercial areas or in a city not only increases pedestrian safety, but also contributes to reducing the environmental impact of motor vehicles and reducing fuel consumption. In addition, there is also a reduction in the greenhouse gas emissions resulting from the combustion of the fuel.

Physical data acquisition and PWM signal generation using a microcontroller allowing control for DC motor rotation speed

El objetivo de este proyecto es diseñar un sistema capaz de controlar la velocidad de rotación de un motor DC en función del valor de temperatura obtenido de un sensor. Para ello se generará con un microcontrolador una señal PWM, cuyo ciclo de trabajo estará en función de la temperatura medida. En lo que respecta a la fase de diseño, hay dos partes claramente diferenciadas, relativas al hardware y al software. En cuanto al diseño del hardware puede hacerse a su vez una división en dos partes. En primer lugar, hubo que diseñar la circuitería necesaria para adaptar los niveles de tensión entregados por el sensor de temperatura a los niveles requeridos por ADC, requerido para digitalizar la información para su posterior procesamiento por parte del microcontrolador. Por tanto hubo que diseñar capaz de corregir el offset y la pendiente de la función tensión-temperatura del sensor, a fin de adaptarlo al rango de tensión requerido por el ADC. Por otro lado, hubo que diseñar el circuito encargado de controlar la velocidad de rotación del motor. Este circuito estará basado en un transistor MOSFET en conmutación, controlado mediante una señal PWM como se mencionó anteriormente. De esta manera, al variar el ciclo de trabajo de la señal PWM, variará de manera proporcional la tensión que cae en el motor, y por tanto su velocidad de rotación. En cuanto al diseño del software, se programó el microcontrolador para que generase una señal PWM en uno de sus pines en función del valor entregado por el ADC, a cuya entrada está conectada la tensión obtenida del circuito creado para adaptar la tensión generada por el sensor. Así mismo, se utiliza el microcontrolador para representar el valor de temperatura obtenido en una pantalla LCD. Para este proyecto se eligió una placa de desarrollo mbed, que incluye el microcontrolador integrado, debido a que facilita la tarea del prototipado. Posteriormente se procedió a la integración de ambas partes, y testeado del sistema para comprobar su correcto funcionamiento. Puesto que el resultado depende de la temperatura medida, fue necesario simular variaciones en ésta, para así comprobar los resultados obtenidos a distintas temperaturas. Para este propósito se empleó una bomba de aire caliente. Una vez comprobado el funcionamiento, como último paso se diseñó la placa de circuito impreso. Como conclusión, se consiguió desarrollar un sistema con un nivel de exactitud y precisión aceptable, en base a las limitaciones del sistema. SUMMARY: It is obvious that day by day people’s daily life depends more on technology and science. Tasks tend to be done automatically, making them simpler and as a result, user life is more comfortable. Every single task that can be controlled has an electronic system behind. In this project, a control system based on a microcontroller was designed for a fan, allowing it to go faster when temperature rises or slowing down as the environment gets colder. For this purpose, a microcontroller was programmed to generate a signal, to control the rotation speed of the fan depending on the data acquired from a temperature sensor. After testing the whole design developed in the laboratory, the next step taken was to build a prototype, which allows future improvements in the system that are discussed in the corresponding section of the thesis.

Mapping wide row crops with video sequences acquired from a tractor moving at treatment speed

This paper presents a mapping method for wide row crop fields. The resulting map shows the crop rows and weeds present in the inter-row spacing. Because field videos are acquired with a camera mounted on top of an agricultural vehicle, a method for image sequence stabilization was needed and consequently designed and developed. The proposed stabilization method uses the centers of some crop rows in the image sequence as features to be tracked, which compensates for the lateral movement (sway) of the camera and leaves the pitch unchanged. A region of interest is selected using the tracked features, and an inverse perspective technique transforms the selected region into a bird’s-eye view that is centered on the image and that enables map generation. The algorithm developed has been tested on several video sequences of different fields recorded at different times and under different lighting conditions, with good initial results. Indeed, lateral displacements of up to 66% of the inter-row spacing were suppressed through the stabilization process, and crop rows in the resulting maps appear straight

Influence of local wind speed and direction on wind power dynamics - Application to offshore very short-term forecasting

Wind power time series usually show complex dynamics mainly due to non-linearities related to the wind physics and the power transformation process in wind farms. This article provides an approach to the incorporation of observed local variables (wind speed and direction) to model some of these effects by means of statistical models. To this end, a benchmarking between two different families of varying-coefficient models (regime-switching and conditional parametric models) is carried out. The case of the offshore wind farm of Horns Rev in Denmark has been considered. The analysis is focused on one-step ahead forecasting and a time series resolution of 10 min. It has been found that the local wind direction contributes to model some features of the prevailing winds, such as the impact of the wind direction on the wind variability, whereas the non-linearities related to the power transformation process can be introduced by considering the local wind speed. In both cases, conditional parametric models showed a better performance than the one achieved by the regime-switching strategy. The results attained reinforce the idea that each explanatory variable allows the modelling of different underlying effects in the dynamics of wind power time series.

Applications for wireless sensor networks : tracking with binary proximity sensors

El interés cada vez mayor por las redes de sensores inalámbricos pueden ser entendido simplemente pensando en lo que esencialmente son: un gran número de pequeños nodos sensores autoalimentados que recogen información o detectan eventos especiales y se comunican de manera inalámbrica, con el objetivo final de entregar sus datos procesados a una estación base. Los nodos sensores están densamente desplegados dentro del área de interés, se pueden desplegar al azar y tienen capacidad de cooperación. Por lo general, estos dispositivos son pequeños y de bajo costo, de modo que pueden ser producidos y desplegados en gran numero aunque sus recursos en términos de energía, memoria, velocidad de cálculo y ancho de banda están enormemente limitados. Detección, tratamiento y comunicación son tres elementos clave cuya combinación en un pequeño dispositivo permite lograr un gran número de aplicaciones. Las redes de sensores proporcionan oportunidades sin fin, pero al mismo tiempo plantean retos formidables, tales como lograr el máximo rendimiento de una energía que es escasa y por lo general un recurso no renovable. Sin embargo, los recientes avances en la integración a gran escala, integrado de hardware de computación, comunicaciones, y en general, la convergencia de la informática y las comunicaciones, están haciendo de esta tecnología emergente una realidad. Del mismo modo, los avances en la nanotecnología están empezando a hacer que todo gire entorno a las redes de pequeños sensores y actuadores distribuidos. Hay diferentes tipos de sensores tales como sensores de presión, acelerómetros, cámaras, sensores térmicos o un simple micrófono. Supervisan las condiciones presentes en diferentes lugares tales como la temperatura, humedad, el movimiento, la luminosidad, presión, composición del suelo, los niveles de ruido, la presencia o ausencia de ciertos tipos de objetos, los niveles de tensión mecánica sobre objetos adheridos y las características momentáneas tales como la velocidad , la dirección y el tamaño de un objeto, etc. Se comprobara el estado de las Redes Inalámbricas de Sensores y se revisaran los protocolos más famosos. Así mismo, se examinara la identificación por radiofrecuencia (RFID) ya que se está convirtiendo en algo actual y su presencia importante. La RFID tiene un papel crucial que desempeñar en el futuro en el mundo de los negocios y los individuos por igual. El impacto mundial que ha tenido la identificación sin cables está ejerciendo fuertes presiones en la tecnología RFID, los servicios de investigación y desarrollo, desarrollo de normas, el cumplimiento de la seguridad y la privacidad y muchos más. Su potencial económico se ha demostrado en algunos países mientras que otros están simplemente en etapas de planificación o en etapas piloto, pero aun tiene que afianzarse o desarrollarse a través de la modernización de los modelos de negocio y aplicaciones para poder tener un mayor impacto en la sociedad. Las posibles aplicaciones de redes de sensores son de interés para la mayoría de campos. La monitorización ambiental, la guerra, la educación infantil, la vigilancia, la micro-cirugía y la agricultura son solo unos pocos ejemplos de los muchísimos campos en los que tienen cabida las redes mencionadas anteriormente. Estados Unidos de América es probablemente el país que más ha investigado en esta área por lo que veremos muchas soluciones propuestas provenientes de ese país. Universidades como Berkeley, UCLA (Universidad de California, Los Ángeles) Harvard y empresas como Intel lideran dichas investigaciones. Pero no solo EE.UU. usa e investiga las redes de sensores inalámbricos. La Universidad de Southampton, por ejemplo, está desarrollando una tecnología para monitorear el comportamiento de los glaciares mediante redes de sensores que contribuyen a la investigación fundamental en glaciología y de las redes de sensores inalámbricos. Así mismo, Coalesenses GmbH (Alemania) y Zurich ETH están trabajando en diversas aplicaciones para redes de sensores inalámbricos en numerosas áreas. Una solución española será la elegida para ser examinada más a fondo por ser innovadora, adaptable y polivalente. Este estudio del sensor se ha centrado principalmente en aplicaciones de tráfico, pero no se puede olvidar la lista de más de 50 aplicaciones diferentes que ha sido publicada por la firma creadora de este sensor específico. En la actualidad hay muchas tecnologías de vigilancia de vehículos, incluidos los sensores de bucle, cámaras de video, sensores de imagen, sensores infrarrojos, radares de microondas, GPS, etc. El rendimiento es aceptable, pero no suficiente, debido a su limitada cobertura y caros costos de implementación y mantenimiento, especialmente este ultimo. Tienen defectos tales como: línea de visión, baja exactitud, dependen mucho del ambiente y del clima, no se puede realizar trabajos de mantenimiento sin interrumpir las mediciones, la noche puede condicionar muchos de ellos, tienen altos costos de instalación y mantenimiento, etc. Por consiguiente, en las aplicaciones reales de circulación, los datos recibidos son insuficientes o malos en términos de tiempo real debido al escaso número de detectores y su costo. Con el aumento de vehículos en las redes viales urbanas las tecnologías de detección de vehículos se enfrentan a nuevas exigencias. Las redes de sensores inalámbricos son actualmente una de las tecnologías más avanzadas y una revolución en la detección de información remota y en las aplicaciones de recogida. Las perspectivas de aplicación en el sistema inteligente de transporte son muy amplias. Con este fin se ha desarrollado un programa de localización de objetivos y recuento utilizando una red de sensores binarios. Esto permite que el sensor necesite mucha menos energía durante la transmisión de información y que los dispositivos sean más independientes con el fin de tener un mejor control de tráfico. La aplicación se centra en la eficacia de la colaboración de los sensores en el seguimiento más que en los protocolos de comunicación utilizados por los nodos sensores. Las operaciones de salida y retorno en las vacaciones son un buen ejemplo de por qué es necesario llevar la cuenta de los coches en las carreteras. Para ello se ha desarrollado una simulación en Matlab con el objetivo localizar objetivos y contarlos con una red de sensores binarios. Dicho programa se podría implementar en el sensor que Libelium, la empresa creadora del sensor que se examinara concienzudamente, ha desarrollado. Esto permitiría que el aparato necesitase mucha menos energía durante la transmisión de información y los dispositivos sean más independientes. Los prometedores resultados obtenidos indican que los sensores de proximidad binarios pueden formar la base de una arquitectura robusta para la vigilancia de áreas amplias y para el seguimiento de objetivos. Cuando el movimiento de dichos objetivos es suficientemente suave, no tiene cambios bruscos de trayectoria, el algoritmo ClusterTrack proporciona un rendimiento excelente en términos de identificación y seguimiento de trayectorias los objetos designados como blancos. Este algoritmo podría, por supuesto, ser utilizado para numerosas aplicaciones y se podría seguir esta línea de trabajo para futuras investigaciones. No es sorprendente que las redes de sensores de binarios de proximidad hayan atraído mucha atención últimamente ya que, a pesar de la información mínima de un sensor de proximidad binario proporciona, las redes de este tipo pueden realizar un seguimiento de todo tipo de objetivos con la precisión suficiente. Abstract The increasing interest in wireless sensor networks can be promptly understood simply by thinking about what they essentially are: a large number of small sensing self-powered nodes which gather information or detect special events and communicate in a wireless fashion, with the end goal of handing their processed data to a base station. The sensor nodes are densely deployed inside the phenomenon, they deploy random and have cooperative capabilities. Usually these devices are small and inexpensive, so that they can be produced and deployed in large numbers, and so their resources in terms of energy, memory, computational speed and bandwidth are severely constrained. Sensing, processing and communication are three key elements whose combination in one tiny device gives rise to a vast number of applications. Sensor networks provide endless opportunities, but at the same time pose formidable challenges, such as the fact that energy is a scarce and usually non-renewable resource. However, recent advances in low power Very Large Scale Integration, embedded computing, communication hardware, and in general, the convergence of computing and communications, are making this emerging technology a reality. Likewise, advances in nanotechnology and Micro Electro-Mechanical Systems are pushing toward networks of tiny distributed sensors and actuators. There are different sensors such as pressure, accelerometer, camera, thermal, and microphone. They monitor conditions at different locations, such as temperature, humidity, vehicular movement, lightning condition, pressure, soil makeup, noise levels, the presence or absence of certain kinds of objects, mechanical stress levels on attached objects, the current characteristics such as speed, direction and size of an object, etc. The state of Wireless Sensor Networks will be checked and the most famous protocols reviewed. As Radio Frequency Identification (RFID) is becoming extremely present and important nowadays, it will be examined as well. RFID has a crucial role to play in business and for individuals alike going forward. The impact of ‘wireless’ identification is exerting strong pressures in RFID technology and services research and development, standards development, security compliance and privacy, and many more. The economic value is proven in some countries while others are just on the verge of planning or in pilot stages, but the wider spread of usage has yet to take hold or unfold through the modernisation of business models and applications. Possible applications of sensor networks are of interest to the most diverse fields. Environmental monitoring, warfare, child education, surveillance, micro-surgery, and agriculture are only a few examples. Some real hardware applications in the United States of America will be checked as it is probably the country that has investigated most in this area. Universities like Berkeley, UCLA (University of California, Los Angeles) Harvard and enterprises such as Intel are leading those investigations. But not just USA has been using and investigating wireless sensor networks. University of Southampton e.g. is to develop technology to monitor glacier behaviour using sensor networks contributing to fundamental research in glaciology and wireless sensor networks. Coalesenses GmbH (Germany) and ETH Zurich are working in applying wireless sensor networks in many different areas too. A Spanish solution will be the one examined more thoroughly for being innovative, adaptable and multipurpose. This study of the sensor has been focused mainly to traffic applications but it cannot be forgotten the more than 50 different application compilation that has been published by this specific sensor’s firm. Currently there are many vehicle surveillance technologies including loop sensors, video cameras, image sensors, infrared sensors, microwave radar, GPS, etc. The performance is acceptable but not sufficient because of their limited coverage and expensive costs of implementation and maintenance, specially the last one. They have defects such as: line-ofsight, low exactness, depending on environment and weather, cannot perform no-stop work whether daytime or night, high costs for installation and maintenance, etc. Consequently, in actual traffic applications the received data is insufficient or bad in terms of real-time owed to detector quantity and cost. With the increase of vehicle in urban road networks, the vehicle detection technologies are confronted with new requirements. Wireless sensor network is the state of the art technology and a revolution in remote information sensing and collection applications. It has broad prospect of application in intelligent transportation system. An application for target tracking and counting using a network of binary sensors has been developed. This would allow the appliance to spend much less energy when transmitting information and to make more independent devices in order to have a better traffic control. The application is focused on the efficacy of collaborative tracking rather than on the communication protocols used by the sensor nodes. Holiday crowds are a good case in which it is necessary to keep count of the cars on the roads. To this end a Matlab simulation has been produced for target tracking and counting using a network of binary sensors that e.g. could be implemented in Libelium’s solution. Libelium is the enterprise that has developed the sensor that will be deeply examined. This would allow the appliance to spend much less energy when transmitting information and to make more independent devices. The promising results obtained indicate that binary proximity sensors can form the basis for a robust architecture for wide area surveillance and tracking. When the target paths are smooth enough ClusterTrack particle filter algorithm gives excellent performance in terms of identifying and tracking different target trajectories. This algorithm could, of course, be used for different applications and that could be done in future researches. It is not surprising that binary proximity sensor networks have attracted a lot of attention lately. Despite the minimal information a binary proximity sensor provides, networks of these sensing modalities can track all kinds of different targets classes accurate enough.

Effect of endurance, speed and strength training on skin temperature measured by infrared thermography = Efecto del entrenamiento de resistencia, velocidad y fuerza en la temperatura de la piel a través de la termografía infrarroja

La termografía infrarroja (TI) es una técnica no invasiva y de bajo coste que permite, con el simple acto de tomar una fotografía, el registro sin contacto de la energía que irradia el cuerpo humano (Akimov & Son’kin, 2011, Merla et al., 2005, Ng et al., 2009, Costello et al., 2012, Hildebrandt et al., 2010). Esta técnica comenzó a utilizarse en el ámbito médico en los años 60, pero debido a los malos resultados como herramienta diagnóstica y la falta de protocolos estandarizados (Head & Elliot, 2002), ésta se dejó de utilizar en detrimento de otras técnicas más precisas a nivel diagnóstico. No obstante, las mejoras tecnológicas de la TI en los últimos años han hecho posible un resurgimiento de la misma (Jiang et al., 2005, Vainer et al., 2005, Cheng et al., 2009, Spalding et al., 2011, Skala et al., 2012), abriendo el camino a nuevas aplicaciones no sólo centradas en el uso diagnóstico. Entre las nuevas aplicaciones, destacamos las que se desarrollan en el ámbito de la actividad física y el deporte, donde recientemente se ha demostrado que los nuevos avances con imágenes de alta resolución pueden proporcionar información muy interesante sobre el complejo sistema de termorregulación humana (Hildebrandt et al., 2010). Entre las nuevas aplicaciones destacan: la cuantificación de la asimilación de la carga de trabajo físico (Čoh & Širok, 2007), la valoración de la condición física (Chudecka et al., 2010, 2012, Akimov et al., 2009, 2011, Merla et al., 2010), la prevención y seguimiento de lesiones (Hildebrandt et al., 2010, 2012, Badža et al., 2012, Gómez Carmona, 2012) e incluso la detección de agujetas (Al-Nakhli et al., 2012). Bajo estas circunstancias, se acusa cada vez más la necesidad de ampliar el conocimiento sobre los factores que influyen en la aplicación de la TI en los seres humanos, así como la descripción de la respuesta de la temperatura de la piel (TP) en condiciones normales, y bajo la influencia de los diferentes tipos de ejercicio. Por consiguiente, este estudio presenta en una primera parte una revisión bibliográfica sobre los factores que afectan al uso de la TI en los seres humanos y una propuesta de clasificación de los mismos. Hemos analizado la fiabilidad del software Termotracker, así como su reproducibilidad de la temperatura de la piel en sujetos jóvenes, sanos y con normopeso. Finalmente, se analizó la respuesta térmica de la piel antes de un entrenamiento de resistencia, velocidad y fuerza, inmediatamente después y durante un período de recuperación de 8 horas. En cuanto a la revisión bibliográfica, hemos propuesto una clasificación para organizar los factores en tres grupos principales: los factores ambientales, individuales y técnicos. El análisis y descripción de estas influencias deben representar la base de nuevas investigaciones con el fin de utilizar la TI en las mejores condiciones. En cuanto a la reproducibilidad, los resultados mostraron valores excelentes para imágenes consecutivas, aunque la reproducibilidad de la TP disminuyó ligeramente con imágenes separadas por 24 horas, sobre todo en las zonas con valores más fríos (es decir, zonas distales y articulaciones). Las asimetrías térmicas (que normalmente se utilizan para seguir la evolución de zonas sobrecargadas o lesionadas) también mostraron excelentes resultados pero, en este caso, con mejores valores para las articulaciones y el zonas centrales (es decir, rodillas, tobillos, dorsales y pectorales) que las Zonas de Interés (ZDI) con valores medios más calientes (como los muslos e isquiotibiales). Los resultados de fiabilidad del software Termotracker fueron excelentes en todas las condiciones y parámetros. En el caso del estudio sobre los efectos de los entrenamientos de la velocidad resistencia y fuerza en la TP, los resultados muestran respuestas específicas según el tipo de entrenamiento, zona de interés, el momento de la evaluación y la función de las zonas analizadas. Los resultados mostraron que la mayoría de las ZDI musculares se mantuvieron significativamente más calientes 8 horas después del entrenamiento, lo que indica que el efecto del ejercicio sobre la TP perdura por lo menos 8 horas en la mayoría de zonas analizadas. La TI podría ser útil para cuantificar la asimilación y recuperación física después de una carga física de trabajo. Estos resultados podrían ser muy útiles para entender mejor el complejo sistema de termorregulación humano, y por lo tanto, para utilizar la TI de una manera más objetiva, precisa y profesional con visos a mejorar las nuevas aplicaciones termográficas en el sector de la actividad física y el deporte Infrared Thermography (IRT) is a safe, non-invasive and low-cost technique that allows the rapid and non-contact recording of the irradiated energy released from the body (Akimov & Son’kin, 2011; Merla et al., 2005; Ng et al., 2009; Costello et al., 2012; Hildebrandt et al., 2010). It has been used since the early 1960’s, but due to poor results as diagnostic tool and a lack of methodological standards and quality assurance (Head et al., 2002), it was rejected from the medical field. Nevertheless, the technological improvements of IRT in the last years have made possible a resurgence of this technique (Jiang et al., 2005; Vainer et al., 2005; Cheng et al., 2009; Spalding et al., 2011; Skala et al., 2012), paving the way to new applications not only focused on the diagnose usages. Among the new applications, we highlighted those in physical activity and sport fields, where it has been recently proven that a high resolution thermal images can provide us with interesting information about the complex thermoregulation system of the body (Hildebrandt et al., 2010), information than can be used as: training workload quantification (Čoh & Širok, 2007), fitness and performance conditions (Chudecka et al., 2010, 2012; Akimov et al., 2009, 2011; Merla et al., 2010; Arfaoui et al., 2012), prevention and monitoring of injuries (Hildebrandt et al., 2010, 2012; Badža et al., 2012, Gómez Carmona, 2012) and even detection of Delayed Onset Muscle Soreness – DOMS- (Al-Nakhli et al., 2012). Under this context, there is a relevant necessity to broaden the knowledge about factors influencing the application of IRT on humans, and to better explore and describe the thermal response of Skin Temperature (Tsk) in normal conditions, and under the influence of different types of exercise. Consequently, this study presents a literature review about factors affecting the application of IRT on human beings and a classification proposal about them. We analysed the reliability of the software Termotracker®, and also its reproducibility of Tsk on young, healthy and normal weight subjects. Finally, we examined the Tsk thermal response before an endurance, speed and strength training, immediately after and during an 8-hour recovery period. Concerning the literature review, we proposed a classification to organise the factors into three main groups: environmental, individual and technical factors. Thus, better exploring and describing these influence factors should represent the basis of further investigations in order to use IRT in the best and optimal conditions to improve its accuracy and results. Regarding the reproducibility results, the outcomes showed excellent values for consecutive images, but the reproducibility of Tsk slightly decreased with time, above all in the colder Regions of Interest (ROI) (i.e. distal and joint areas). The side-to-side differences (ΔT) (normally used to follow the evolution of some injured or overloaded ROI) also showed highly accurate results, but in this case with better values for joints and central ROI (i.e. Knee, Ankles, Dorsal and Pectoral) than the hottest muscle ROI (as Thigh or Hamstrings). The reliability results of the IRT software Termotracker® were excellent in all conditions and parameters. In the part of the study about the effects on Tsk of aerobic, speed and strength training, the results of Tsk demonstrated specific responses depending on the type of training, ROI, moment of the assessment and the function of the considered ROI. The results showed that most of muscular ROI maintained warmer significant Tsk 8 hours after the training, indicating that the effect of exercise on Tsk last at least 8 hours in most of ROI, as well as IRT could help to quantify the recovery status of the athlete as workload assimilation indicator. Those results could be very useful to better understand the complex skin thermoregulation behaviour, and therefore, to use IRT in a more objective, accurate and professional way to improve the new IRT applications for the physical activity and sport sector.

Advances in the analysis of short span railway bridges for high-speed lines

The physical model based on moving constant loads is widely used for the analysis of railway bridges. Nevertheless, the moving loads model is not well suited for the study of short bridges (L⩽20–25 m) since the results it produces (displacements and accelerations) are much greater than those obtained from more sophisticated ones. In this paper two factors are analysed which are believed to have an influence in the dynamic behaviour of short bridges. These two factors are not accounted for by the moving loads model and are the following: the distribution of the loads due to the presence of the sleepers and ballast layer, and the train–bridge interaction. In order to decide on their influence several numerical simulations have been performed. The results are presented and discussed herein.

Efficient computation of the pressures developed during high-speed train passing events

The paper resumes the results obtained applying various implementations of the direct boundary element method (BEM) to the solution of the Laplace Equation governing the potential flow problem during everyday service manoeuvres of high-speed trains. In particular the results of train passing events at three different speed combinations are presented. Some recommendations are given in order to reduce calculation times which as is demonstrated can be cut down to not exceed reasonable limits even when using nowadays office PCs. Thus the method is shown to be a very valuable tool for the design engineer.

High-Speed Rail Versus Air Transportation: Case Study of Madrid–Barcelona, Spain.

Travel time savings, better quality of the supplied services, greater comfort for the users, and improved accessibility are the main factors of success of High Speed Rail(HSR)links. This paper presents the results from a revealed and stated preference survey conducted to both HSR and air transport users in the Madrid Barcelona corridor. The data gathered from the stated preference survey was used to calibrate a modal choice model aiming at explaining competition between HSR and air transportation in the corridor. From the model, the authors obtain that prices and service frequency are the most important variables to compete with the other mode. In addition, they found that check-in and security controls at the airport are a crucial variable for the users in their modal choice. Other policies, such as the improvement of parking facilities at the train stations, play a secondary role.

Efficiency and spatial equity impacts of high-speed rail extensions in urban areas

Urban areas benefit from significant improvements in accessibility when a new high speed rail (HSR) project is built. These improvements, which are due mainly to a rise in efficiency, produce locational advantagesand increase the attractiveness of these cities, thereby possibly enhancing their competitivenessand economic growth. However, there may be equity issues at stake, as the main accessibility benefits are primarily concentrated in urban areas with a HSR station, whereas other locations obtain only limited benefits. HSR extensions may contribute to an increase in spatial imbalance and lead to more polarized patterns of spatial development. Procedures for assessing the spatial impacts of HSR must therefore follow a twofold approach which addresses issues of both efficiency and equity. This analysis can be made by jointly assessing both the magnitude and distribution of the accessibility improvements deriving from a HSR project. This paper describes an assessment methodology for HSR projects which follows this twofold approach. The procedure uses spatial impact analysis techniques and is based on the computation of accessibility indicators, supported by a Geographical Information System (GIS). Efficiency impacts are assessed in terms of the improvements in accessibility resulting from the HSR project, with a focus on major urban areas; and spatial equity implications are derived from changes in the distribution of accessibility values among these urban agglomerations.

Dynamic response of underpasses for high-speed train lines

Underpasses are common in modern railway lines. Wildlife corridors and drainage conduits often fall into this category of partially buried structures. Their dynamic behavior has received far less attention than that of other structures such as bridges, but their large number makes their study an interesting challenge from the viewpoint of safety and cost savings. Here, we present a complete study of a culvert, including on-site measurements and numerical modeling. The studied structure belongs to the high-speed railway line linking Segovia and Valladolid in Spain. The line was opened to traffic in 2004. On-site measurements were performed for the structure by recording the dynamic response at selected points of the structure during the passage of high-speed trains at speeds ranging between 200 and 300 km/h. The measurements provide not only reference values suitable for model fitting, but also a good insight into the main features of the dynamic behavior of this structure. Finite element techniques were used to model the dynamic behavior of the structure and its key features. Special attention is paid to vertical accelerations, the values of which should be limited to avoid track instability according to Eurocode. This study furthers our understanding of the dynamic response of railway underpasses to train loads.

Use of STATCOM in wind farms with fixed-speed generators for grid code compliance

The increasing penetration of wind energy into power systems has pushed grid operators to set new requirements for this kind of generating plants in order to keep acceptable and reliable operation of the system. In addition to the low voltage ride through capability, wind farms are required to participate in voltage support, stability enhancement and power quality improvement. This paper presents a solution for wind farms with fixed-speed generators based on the use of STATCOM with braking resistor and additional series impedances, with an adequate control strategy. The focus is put on guaranteeing the grid code compliance when the wind farm faces an extensive series of grid disturbances.

Comparison of dynamic effects of high-speed traffic load on ballasted track using a simplified two-dimensional and full three-dimensional model.

The vertical dynamic actions transmitted by railway vehicles to the ballasted track infrastructure is evaluated taking into account models with different degree of detail. In particular, we have studied this matter from a two-dimensional (2D) finite element model to a fully coupled three-dimensional (3D) multi-body finite element model. The vehicle and track are coupled via a non-linear Hertz contact mechanism. The method of Lagrange multipliers is used for the contact constraint enforcement between wheel and rail. Distributed elevation irregularities are generated based on power spectral density (PSD) distributions which are taken into account for the interaction. The numerical simulations are performed in the time domain, using a direct integration method for solving the transient problem due to the contact nonlinearities. The results obtained include contact forces, forces transmitted to the infrastructure (sleeper) by railpads and envelopes of relevant results for several track irregularities and speed ranges. The main contribution of this work is to identify and discuss coincidences and differences between discrete 2D models and continuum 3D models, as wheel as assessing the validity of evaluating the dynamic loading on the track with simplified 2D models

The Dynamics of High-Speed Railway Bridges: A Review of Design Issues and New Research for Lateral Dynamics

The dynamic effects of high-speed trains on viaducts are important issues for the design of the structures, as well as for the consideration of safe running conditions for the trains. In this work we start by reviewing the relevance of some basic design aspects. The significance of impact factor envelopes for moving loads is considered first. Resonance which may be achieved for high-speed trains requires dynamic analysis, for which some key aspects are discussed. The relevance of performing a longitudinal distribution of axle loads, the number of modes taken in analysis, and the consideration of vehicle-structure interaction are discussed with representative examples. The lateral dynamic effects of running trains on bridges is of importance for laterally compliant viaducts, such as some very tall structures erected in new high-speed lines. The relevance of this study is mainly for the safety of the traffic, considering both internal actions such as the hunting motion as well as external actions such as wind or earthquakes [1]. These studies require three-dimensional dynamic coupled vehicle-bridge models, and consideration of wheel to rail contact, a phenomenon which is complex and costly to model in detail. We describe here a fully nonlinear coupled model, described in absolute coordinates and incorporated into a commercial finite element framework [2]. The wheel-rail contact has been considered using a FastSim algorithm which provides a compromise between accuracy and computational cost, and captures the main nonlinear response of the contact interface. Two applications are presented, firstly to a vehicle subject to a strong wind gust traversing a bridge, showing the relevance of the nonlinear wheel-rail contact model as well as the dynamic interaction between bridge and vehicle. The second application is to a real HS viaduct with a long continuous deck and tall piers and high lateral compliance [3]. The results show the safety of the traffic as well as the importance of considering features such as track alignment irregularities.

Training-induced changes in drag-flick technique in female field hockey players

The penalty corner is one of the most important goal plays in field hockey. The drag-flick is used less by women than men in a penalty corner. The aim of this study was to describe training-induced changes in the drag-flick technique in female field hockey players. Four female players participated in the study. The VICON optoelectronic system (Oxford Metrics, Oxford, UK) measured the kinematic parameters of the drag-flick with six cameras sampling at 250 Hz, prior to and after training. Fifteen shots were captured for each subject. A Wilcoxon test assessed the differences between pre-training and post-training parameters. Two players received specific training twice a week for 8 weeks; the other two players did not train. The proposed drills improved the position of the stick at the beginning of the shot (p<0.05), the total distance of the shot (p<0.05)and the rotation radius at ball release (p<0.01). It was noted that all players had lost speed of the previous run. Further studies should include a larger sample, in order to provide more information on field hockey performance.