Foram medidas as perdas de ernergia de íons 14N e 16O em sólidos (Si,Ti,V,Cu,Zn, Zr e Pd) na faixa de energias de 1 MeV/uma. A técnica utilizada constitui-se na medida de energia de projéteis espalhados a 25° por um alvo delgado de Au, antes e depois de atravessar a folha do element freador. Os resultados experimentais são comparados com as previsões semi-empíricas de Northcliffe & Schilling (N&S), Ziegler e uma nova versão de N&S feita por Hubert e colaboradores, sendo observada uma razoável concordância entre os valores medidos e as curvas semi-empíricas. / Energy loss has been measured 14N and 16O at energies of 1 MeV/amu to 4 MeV/amu in Si, Ti, V, Cu, Zn, Zr and Pd foils. The technique consists in the measurement of the energies of ions scattered through 25 ° by a goldfoil before and after passing through the stopping foil. Our data compared to the semiempirical tabulations of Northcliffe and Schilling (N&S), Ziegler and new version of N&S by Hubert et al.. The predictions of these semiempirical compilations are in reasonable agreement with our experimental data.

Considerando o nível de competitividade do mercado automobilístico atual, a satisfação do cliente tem se tornado uma vantagem competitiva a ser considerada, devido ao aumento da expectativa dos clientes em relação à percepção da qualidade. Neste aspecto, uma das maiores dificuldades existentes no projeto de sistemas de freio reside no fato de transformar informações e/ou opiniões subjetivas em informações e/ou dados objetivos, tais como parâmetros de projeto. O presente trabalho investiga a análise objetiva do conforto de frenagem de automóveis de passeio, estabelecendo indicadores que auxiliem e/ou complementem as análises subjetivas normalmente utilizadas pela empresa, para um estudo de caso envolvendo a mudança de material de atrito da pastilha do freio a disco de um automóvel de passeio. Foram utilizados para a análise objetiva, programas de simulação computacional para analisar o desempenho do sistema de freio com relação aos indicadores estabelecidos. Os dados obtidos através desta simulação foram comparados, tanto com os resultados da avaliação subjetiva, quanto aos resultados de medições experimentais do veículo analisado, buscando analisar a correlação dos resultados. Ao final do trabalho, da comparação realizada entre a avaliação subjetiva e a avaliação objetiva observou-se uma melhoria no conforto de frenagem aos usuários, apesar de ser imperceptível na avaliação subjetiva. Esta ferramenta será muito importante no estabelecimento da curva de conforto de frenagem ótima para os novos desenvolvimentos de sistemas de freio eletrohidráulicos, denominados “brake-by-wire" (BBW). / Considering today’s competitive automotive market, the customer satisfaction has become a competitive advantage to be considered, due to the customer expectation increasing regarding the quality perception. In this aspect, one of biggest existing difficulties in the brake system design is to transform subjective information and/or opinions into objective information and/or data, such as design parameters. The present study investigates the objective analysis of the brake pedal feeling for passenger cars, establishing index that can support and/or complement the subjective analysis, usually used by our company, for a study case involving the friction material change of passenger car’s caliper brake pad. The computational simulation program has been used for the objective analysis, to analyze the brake system performance based on established index. The obtained data through this simulation was compared with the subjective evaluation results as much as with experimental measurements results of the analyzed vehicle, analyzing the correlation of results. To the end of this study, based on the comparison between subjective evaluation and objective evaluation, it observed a brake comfort improvement for drivers, instead of this characteristic would be imperceptive in subjective evaluation. This tool will be very important in the optimum comfort curve establishment for the new developments of electro-hydraulic brake systems, called "brake-by-wire" (BBW).

The limitations of current simulation packages in addressing the true longitudinal behaviour of railway bogie dynamics during braking/traction has prompted the development of a Rail Bogie Dynamics (RBD) program in this thesis. The RBD program offers novel features for the calculation of the speed profile as a function of the brake torque as well as explicitly determining wheelset angular velocity. With such capability, the speed profile is no longer treated as an input calculated as a priori as required by most of the current simulation systems. The RBD program has been developed using a formulation that includes the wheelset pitch degree of freedom explicitly with a coordinate reference system that is fixed in space and time. The formulation has made the simulation of the bogie dynamics during braking/traction possible in a natural way using the brake/traction torque as the input and the resulting speed profile as the output without any need for working out the speed profile as a priori. Consequently, severe dynamics during braking such as the wheelset skid and the onset of wheel climb derailment can be modelled and critical parameters investigated using the RBD program. The RBD program has been validated, where possible, through a series of simulations using a commercial software package (VAMPIRE). For cases which cannot be simulated by VAMPIRE such as the wheelset skid, a novel experimental program has been designed and commissioned in the Heavy Testing Laboratory of the Central Queensland University as reported in this thesis. One of the possible applications of the RBD program in examining the effect of asymmetric brake shoe force in bogies equipped with one-side push brake shoe arrangement is illustrated in this thesis. It is believed that the model and RBD program will have significant benefit in understanding the true longitudinal behaviour of wagons in suburban passenger trains that operate under braking/ traction torques for most of their travel. Similar studies will also be useful to freight train wagon dynamics during entry and exit of speed restriction zones and tight curves.

<p>This report is the result of a master thesis at the Department of Mechanical Engineering, Division of Industrial and Economical Development, at Linköping University of Technology. The project was carried out on behalf of Fanerami AB, Mjölby and includes 20 weeks of full time schedule work.</p><p>Cabinets with vertical mounted roller shutters all share the same problem, namely weight balancing. A roller shutter has an equilibrium area where the sum of the different forces acting on the shutter equals zero. As the shutter leaves that area it will pick up speed as it falls towards the bottom. When the shutter hits the bottom of the cabinet there is a potential risk of getting fingers caught and in this project a solution to prevent this from happening was to be presented.</p><p>In this project, three concepts have been generated with the following different purposes:</p><p>•In concept 1 the risk of getting any fingers caught when the shutter closes was to be eliminated in an efficient and inexpensive way.</p><p>•In concept 2 the roller shutter had to be balanced at all time providing the possibility to keep the cabinet open in any position.</p><p>•The last and most challenging task was to create a remote controlled TV cabinet. The shutters were mounted horizontally and were to be opened simply by pushing the bottom either on the remote transmitter unit or the cabinet.</p><p>The first concept uses a small oil damper, often seen in kitchen cabinets and drawers. The roller shutter applies pressure on the damper via a lever that transforms the shutter motion along a certain path to a smaller motion in the direction of the damper. By doing so, a smaller damper with higher pressure can be used. Dampers are available with several different pressures and can be mounted in five different positions; therefore the concept can be adjusted to fit almost any cabinet.</p><p>Concept 2 consists of a thin cord winded around a wheel. The wheel is equipped with a spring that tightens when the cord is pulled in. The spring produces an equal and opposite force that holds the shutter in balance. As the wheel is mounted in the upper front of the cabinet, underneath the shutter, it will almost be invisible. The concept is easy to adjust to most cabinets by simply attach the shutter at different levels. In that way the spring will be tightened to equal the weight of the shutter.</p><p>The design of the TV cabinet has been a working progress throughout the whole project. A couple of prototypes were produced before the final concept. The mechanical solution is based on two pinion rackets placed one on each side of a rotating pinion powered by a motor through a planetary gearbox. To control the cabinet Electronic Solutions AB developed an electronic system that made it possible to open and close the shutters with a remote control or a switch on the cabinet.</p>

No description available.

All electric machines have two mechanical operations, motoring and braking. The nature of braking can be regenerative, where the kinetic energy of the rotor is converted into electricity and sent back to the power source or non-regenerative, where the source supplies electric power to provide braking. This thesis investigates several critical issues related to regenerative braking in both DC and AC electric machines, including the determination of boundaries in the torque-speed plane defining the regenerative braking capability region and the evaluation of operating points within that capability region that result in maximum regenerative braking recharge current. Electric machines are used in the powertrains of electric and hybrid-electric vehicles to provide motoring or braking torque in response to the driver's request and power management logic. Since such vehicles carry a limited amount of electrical energy on-board their energy storage systems (such as a battery pack), it is important to conserve as much electrical energy as possible in order to increase the range of travel. Therefore, the concept of regenerative braking is of importance for such vehicles since operating in this mode during a braking event sends power back to the energy storage system thereby replenishing its energy level. Since the electric machine assists the mechanical friction braking system of the vehicle, it results in reduced wear on components within the mechanical friction brake system. As both mechanical friction braking and electric machine braking are used to provide the requested vehicle braking torque, braking strategies which relate to splitting of the braking command between the two braking mechanisms are discussed. The reduction in energy consumption of a test vehicle along different driving schedules while using different braking strategies is also studied.

Hybrid electric vehicle technology has become a preferred method for the automotive industry to reduce environmental impact and fuel consumption of their vehicles. Hybrid electric vehicles accomplish these reductions through the use of multiple propulsion systems, namely an electric motor and internal combustion engine, which allow the elimination of idling, operation of the internal combustion engine in a more efficient manner and the use of regenerative braking. However, the added cost of the hybrid electric system has hindered the sales of these vehicles. A more cost effective design of an electro-hydraulic braking system is presented. The system electro-mechanically controlled the boost force created by the brake booster independently of the driver braking force and with adequate time response. The system allowed for the blending of the mechanical and regenerative braking torques in a manner transparent to the driver and allowed for regenerative braking to be conducted efficiently. A systematic design process was followed, with emphasis placed on demonstrating conceptual design feasibility and preliminary design functionality using virtual and physical prototyping. The virtual and physical prototypes were then used in combination as a powerful tool to validate and develop the system. The role of prototyping in the design process is presented and discussed. Through the experiences gained by the author during the design process, it is recommended that students create physical prototypes to enhance their educational experience. These experiences are evident throughout the thesis presented.

Hybrid electric vehicle technology has become a preferred method for the automotive industry to reduce environmental impact and fuel consumption of their vehicles. Hybrid electric vehicles accomplish these reductions through the use of multiple propulsion systems, namely an electric motor and internal combustion engine, which allow the elimination of idling, operation of the internal combustion engine in a more efficient manner and the use of regenerative braking. However, the added cost of the hybrid electric system has hindered the sales of these vehicles. A more cost effective design of an electro-hydraulic braking system is presented. The system electro-mechanically controlled the boost force created by the brake booster independently of the driver braking force and with adequate time response. The system allowed for the blending of the mechanical and regenerative braking torques in a manner transparent to the driver and allowed for regenerative braking to be conducted efficiently. A systematic design process was followed, with emphasis placed on demonstrating conceptual design feasibility and preliminary design functionality using virtual and physical prototyping. The virtual and physical prototypes were then used in combination as a powerful tool to validate and develop the system. The role of prototyping in the design process is presented and discussed. Through the experiences gained by the author during the design process, it is recommended that students create physical prototypes to enhance their educational experience. These experiences are evident throughout the thesis presented.

No description available.

This report is the result of a master thesis at the Department of Mechanical Engineering, Division of Industrial and Economical Development, at Linköping University of Technology. The project was carried out on behalf of Fanerami AB, Mjölby and includes 20 weeks of full time schedule work. Cabinets with vertical mounted roller shutters all share the same problem, namely weight balancing. A roller shutter has an equilibrium area where the sum of the different forces acting on the shutter equals zero. As the shutter leaves that area it will pick up speed as it falls towards the bottom. When the shutter hits the bottom of the cabinet there is a potential risk of getting fingers caught and in this project a solution to prevent this from happening was to be presented. In this project, three concepts have been generated with the following different purposes: •In concept 1 the risk of getting any fingers caught when the shutter closes was to be eliminated in an efficient and inexpensive way. •In concept 2 the roller shutter had to be balanced at all time providing the possibility to keep the cabinet open in any position. •The last and most challenging task was to create a remote controlled TV cabinet. The shutters were mounted horizontally and were to be opened simply by pushing the bottom either on the remote transmitter unit or the cabinet. The first concept uses a small oil damper, often seen in kitchen cabinets and drawers. The roller shutter applies pressure on the damper via a lever that transforms the shutter motion along a certain path to a smaller motion in the direction of the damper. By doing so, a smaller damper with higher pressure can be used. Dampers are available with several different pressures and can be mounted in five different positions; therefore the concept can be adjusted to fit almost any cabinet. Concept 2 consists of a thin cord winded around a wheel. The wheel is equipped with a spring that tightens when the cord is pulled in. The spring produces an equal and opposite force that holds the shutter in balance. As the wheel is mounted in the upper front of the cabinet, underneath the shutter, it will almost be invisible. The concept is easy to adjust to most cabinets by simply attach the shutter at different levels. In that way the spring will be tightened to equal the weight of the shutter. The design of the TV cabinet has been a working progress throughout the whole project. A couple of prototypes were produced before the final concept. The mechanical solution is based on two pinion rackets placed one on each side of a rotating pinion powered by a motor through a planetary gearbox. To control the cabinet Electronic Solutions AB developed an electronic system that made it possible to open and close the shutters with a remote control or a switch on the cabinet.