Visualizing the Doppler Effect

The development of Information and Communication Technologies suggests some spectacular changes in the methods used for teaching scientific subjects. Nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. However, when we are trying to explain some complex physical processes, it is better to simplify the problem under study using simplified pictures of the total process by eliminating some elements that make it difficult to understand this process. In this work we focus our attention on the Doppler effect which requires the space-time visualization that is very difficult to obtain using the traditional teaching resources. We have designed digital simulations as a complement of the theoretical explanation in order to help students understand this phenomenon.Comment: 16 pages, 8 figure

Passenger Exposure to Magnetic Fields in Electric Vehicles

In electric vehicles, passengers sit very close to an electric system of significant power, usually for a considerable amount of time. The relatively high currents achieved in these systems and the short distances between the power devices and the passengers mean that the latter could be exposed to relevant magnetic fields. This implies that it becomes necessary to evaluate the electromagnetic environment in the interior of these vehicles before releasing them in the market. Moreover, the hazards of magnetic field exposure must be taken into account when designing electric vehicles and their components. For this purpose, estimation tools based on finite element simulations can prove to be very useful. With appropriate design guidelines, it might be possible to make electric vehicles safe from the electromagnetic radiation point of view

Educational Project for the Teaching of Control of Electric Traction Drives

Electric vehicles constitute a multidisciplinary subject that involves disciplines such as automotive, mechanical, electrical and control engineering. Due to this multidisciplinary technical nature, practical teaching methodologies are of special relevance. Paradoxically, in the past, the training of engineers specializing in this area has lacked the practical component represented by field tests, due to the difficulty of accessing real systems. This paper presents an educational project specifically designed for the teaching and training of engineering students with different backgrounds and experience. The teaching methodology focuses on the topology of electric traction drives and their control. It includes two stages, a simulation computer model and a scaled laboratory workbench that comprises a traction electrical drive coupled to a vehicle emulator. With this equipment, the effectiveness of different traction control strategies can be analyzed from the point of view of energy efficiency, robustness, easiness of implementation and acoustic noise

Effect of response interference on diminution of electrodermal unconditioned response

El propósito de este experimento es investigar si el fenómeno de disminución condicionada de la respuesta incondicionada (RI) es producido por el mecanismo fisiológico de la interferencia, o fusión, entre la respuesta condicionada (RC) y la RI, tal como sugieren las hipótesis de la interferencia de respuesta y de la inhibición de demora. Sesenta estudiantes voluntarios recibieron entrenamiento discriminativo en el que un estímulo condicionado (EC) era reforzado (EC+/EI) y un segundo EC no era reforzado (EC). El intervalo entre el EC y el estímulo incondicionado (EI; ruido blanco aversivo) era de 8 segundos. Fueron analizados únicamente los resultados de los sujetos que exhibieron control discriminativo. Los resultados muestran que ni la amplitud, ni la latencia de la RC precedente afectan a la amplitud de la RI. Puesto que estos resultados no pueden ser explicados por la hipótesis de la interferencia de respuesta ni de la inhibición de demora, se ofrece una explicación alternativa sugiriendo la existencia de una base asociativa del fenómenoThe purpose of this experiment was to study whether the phenomenon called —conditioned diminution of the unconditioned response (UR)— is produced by the physiological mechanism of response interference, or fusion, between the conditioned response (CR) and the UR, as suggested by the response interference and inhibition of delay hypotheses. Sixty volunteer subjects received discrimination training in which a CS was reinforced (CS+/US) and a second CS was not reinforced (CS-). The interval between the CS and unconditioned stimulus (US; aversive white-noise) was 8 seconds. Only the results of subjects exhibiting discriminative control were analyzed. The results show that neither the amplitude, nor the latency of the preceding CR affect the amplitude of the UR. Because these results cannot be explained by the response interference or inhibition of delay hypotheses, an alternative explanation is offered, suggesting the presence of an associative basis of the phenomenonS

Polyolefin Fibres for the Reinforcement of Concrete

Given that concrete has limited tensile strength, it has been necessary to combine its properties with the use of steel bars. This resulted in the arrival of reinforced concrete which was the main solution used in structures in the last century. Partial or even full substitution of steel bars for fibres would not only allow the cost of a structure to be reduced but also provide certain improved properties. Modern fibre‐reinforced concrete (FRC) now permits reduction or substitution of steel bars that has given rise to the commonly named structural FRC. Advances in the plastic industry during the last three decades have allowed the production of macro‐polymer fibres as an alternative to steel fibres due to their chemical stability and lower weights for analogous residual strengths. After 30 years of research and practice, polyolefin‐based macro‐fibres have offered additional advantages such as safe handling, low pump wear and reduction in weight when transported and stored. This chapter provides an overview of the properties and structural capacities of polyolefin fibre‐reinforced concrete (PFRC). Furthermore, the respective codes and test methods are examined. Moreover, the results obtained for structural design and the mechanical properties, found both in the literature and in practice, are supplied and discussed

Facilitación e interferencia del procesamiento automático de la información sobre una tarea de tiempo de reacción ante estímulos amenazantes

The purpose of this experiment was to study if the threat-relevant stimuli receive automatic processing when presented effectively masked in a priming paradigm. The prime consisted of an angry face (A) as threat-relevant stimulus and a face with neutral expression (N) as threat-irrelevant stimulus. The same stimuli (A and N) were used as target (or mask), giving four masking conditions (A/A, N/N, A/N and N/A). Furthermore, the target was considered an imperative stimulus for a reaction time (RT) task. Thirty-two subjects were exposed to 10 trials of each masking conditions with a stimulus-onset asynchrony (SOA) of 34 milliseconds (ms). The same number of subjects received the same trials, but with a SOA of 51 ms, this being an unmasking presentation of the stimulus. The results demonstrate that an effective masking presentation of a threat-relevant stimulus produces either facilitation or interference with the RT task, depending on whether the target (mask) is a threat-relevant or a threat-irrelevant stimulusEl objetivo de este experimento era estudiar si los estímulos amenazantes reciben procesamiento automático cuando son presentados eficazmente enmascarados en un paradigma de priming. El prime consistió en un rostro con expresión amenazante (A) y una cara con expresión neutra como estímulo irrelevante de amenaza (N). Los mismos estímulos fueron utilizados como target (o máscara), dando lugar a cuatro condiciones de enmascaramiento (A/A, N/N, A/N y N/A). Además, el target fue utilizado como un estímulo imperativo para una tarea de tiempo de reacción (TR). Treinta y dos sujetos fueron expuestos a 10 ensayos de cada condición de enmascaramiento con una asincronía del estímulo (SOA) de 34 milisegundos (ms). Otros tantos sujetos recibieron los mismos ensayos, pero con un SOA de 51 ms. Los resultados demuestran que la presentación eficazmente enmascarada de los estímulos amenazantes produce facilitación o interferencia con la tarea de TR, dependiendo de si el target (máscara) consiste en un estímulo relevante o irrelevante de amenazaS