A designação de estruturas próprias de sistemas dinâmicos com retroação completa de estados ou saídas foi objeto de estudo de muitos pesquisadores durante a segunda metade do século XX. Os trabalhos mais relevantes sobre o tema foram revisados e serviram como base para a elaboração da metodologia apresentada neste trabalho. Que consiste na designação de estruturas próprias desejadas para um sistema linear em malha aberta com a modificação de parâmetros do sistema através da pseudo retroação de saídas devidamente definidas. O método foi aplicado na coxinização de um veículo de passeio. No qual os modos de vibrar de modelos lineares com 7 e 8 graus de liberdade do veículo foram adequados com o intuito de reduzir as acelerações verticais de chassi, características do fenômeno shake de motor e câmbio (faixa de frequência entre 7 e 25 Hz). Para tanto, reduziu-se a participação do grau de liberdade vertical de chassi nos modos com grande participação dos graus de liberdade de motor e massa não suspensa. Os resultados obtidos com a aplicação da metodologia na coxinização foram valores de rigidezes, amortecimentos e características de coxins hidráulicos que resultam na redução significativa da aceleração vertical de chassi, que implica em uma melhora perceptível para o consumidor na qualidade do conforto do veículo. / Eigenstructure assignment using full state or output feedback control had been object of study of many researchers during the second half of XX century. The most important works about eigenstructure assignment were reviewed, specially some applications within aerospace industry, that was the responsible for developing all the theory concerning pole and eigenvector placement. The review of the related theory was also based on the pioneering and most expressive works and were base for the methodology developed and described in this work. Which consists basically on the assignment of some desired eigensctructure of open loop linear systems modifying some parameters of the systems by means pseudo feedback of some outputs into inputs specifically defined. This methodology was applied to a 8 DOF vehicle model, a case of study, in order to adequate the system modes changing engine mounts parameters to improve the vehicle ride comfort, mainly eigenstructures about powertrain shake range frequencies.

Today, Sport Utility Vehicles are marketed as both on-road and off-road vehicles. This results in a compromise when designing the suspension of the vehicle. If the suspension characteristics are fixed, the vehicle cannot have good handling capabilities on highways and good ride comfort over rough terrain. The rollover propensity of this type of vehicle compared to normal cars is high because it has a combination of a high centre of gravity and a softer suspension. The 4 State Semi-active Suspension System (4S4) that can switch between two discrete spring characteristics as well as two discrete damper characteristics, has been proven to overcome this compromise. The soft suspension setting (soft spring and low damping) is used for ride comfort, while the hard suspension setting (stiff spring and high damping) is used for handling. The following question arises: when is which setting most appropriate? The two main contributing factors are the terrain profile and the driver’s actions. Ride comfort is primarily dependant on the terrain that the vehicle is travelling over. If the terrain can be identified, certain driving styles can be expected for that specific environment. The terrains range from rough and uncomfortable to smooth with high speed manoeuvring. Terrain classification methods are proposed and tested with measured data from the test vehicle on known terrain types. Good results were obtained from the terrain classification methods. Five terrain types were accurately identified from over an hour’s worth of vehicle testing. Handling manoeuvres happen unexpectedly, often to avoid an accident. To improve the handling and therefore safety of the vehicle, the 4S4 can be switched to the hard suspension setting, which results in a reduced body roll angle. This decision should be made quickly with the occupants’ safety as the priority. Methods were investigated that will determine when to switch the suspension to the handling mode based on the kinematics of the vehicle. The switching strategies proposed in this study have the potential, with a little refinement, to make the ride versus handling decision correctly. Copyright 2007, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Bester, R 2007, The ride comfort versus handling decision for off-road vehicles, MEng dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-10252007-111611 / > / Dissertation (MEng (Mechanical Engineering))--University of Pretoria, 2007. / Mechanical and Aeronautical Engineering / unrestricted

Diplomová práce se zabývá analýzou a výpočtem optimalizační úlohy z praxe. Jedná se o optimalizaci nočních linek vnitrostátní přepravy na území ČR. Cílem je nalezení řešení, které zefektivní organizaci těchto linek a usnadní práci lidí s nimi spojenou. Celý výpočet úlohy je inspirován okružním problémem s doručením a vyzvednutím (?Pickup and Delivery Problem?). Na výpočet problému jsou použity dva modely: model založený na hledání optimálního více produktového toku a model spočívající na výběru tras. Modely jsou založeny na rozdílných přístupech. Díky oběma modelům je možné si uvědomit, že na jednu optimalizační úlohu lze pohlížet z více stran a z obdržených výsledků si pak vytvořit ucelenější pohled na problém.

This Master’s thesis is focused on the suspension of the front wheel, more accurately for specific part, upright. It describes the basic requirements for construction, distribution of uprights, their method of production and types of materials used. It briefly mentions topology optimization and its two optimization methods. Also deals with vehicle dynamics for driving conditions – standing vehicle, braking and cornering. In the practical part, the work is focused on determining the load effects on the upright during the aforementioned driving conditions using MBS software. At the end of the work, FEM stress and deformation analyses are performed for loading on the wheel side and on the suspension side, which are then compared and evaluated.

Diploma thesis Selected measurements of the motion of bicycles – braking and ridein the curve analyses problematic manoeuvres of bicycle riders according to the most typical accidents including bikes. There will be given statistics of bikers´ participation on accident amount that happened within last few years. The measurements of bicycles moving around bands of specific radiuses as a situation of most bicycle accidents will be described in the next part of this thesis. There will be also specified the values of average bicycle speeds when driving in curves with various radiuses according to types of bicycles, sex and experiences of the riders and will be an output of this thesis. Further on there will be measurements of braking in the direct line on various surfaces with different types of bikes and different brakes used.

The diploma thesis focuses especially on a design of a way for evaluating roughness in road profile, which affects driving characteristics of a car and a ride. In the theoretical part of the thesis are mentioned the most used methods and tools for road roughness analysis in the world. For the purposes of this thesis an experimental measuring were undertaken in order to obtain data for the own design of a road profile analysing system.

Orientador: André Luiz Andreoli / Resumo: Nos últimos anos, questões relacionadas ao meio ambiente, principalmente, ao uso de combustíveis fósseis e à emissão de gases poluentes na atmosfera, ganharam grande destaque internacional. Com os avanços da comunidade científica e o aumento no preço do petróleo no começo da década de 1970, o uso de fontes renováveis, não poluentes e limpas teve grande investimento por parte de diversos países. Nesse contexto, a geração eólica vem se destacando como uma das mais promissoras, especialmente devido a sua viabilidade econômica e ao seu rápido desenvolvimento tecnológico. Entre as diferentes topologias utilizadas nos sistemas de geração eólica, destaca-se a configuração elaborada para operação em velocidade variável, que emprega o gerador de indução duplamente alimentado (DFIG), associado ao conversor eletrônico back-to-back para controle de sua operação. Como principais vantagens da utilização do DFIG, destacam-se sua maior eficiência na conversão de energia, menor estresse mecânico do rotor, controle independente de potência ativa e reativa limitada a valores típicos de 30% da potência nominal. Por outro, sabe-se que, durante a ocorrência de um distúrbio, as correntes do rotor podem atingir altas magnitudes e causar danos ao conversor. Além disso, sobretensões no capacitor do elo CC ocorrem devido à perda de capacidade de transferência de energia do conversor do lado da rede. Entretanto, os aerogeradores podem ser requisitados a permanecerem em funcionamento mesmo durante uma fa... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In the last years, issues related to the environment, especially the use of fossil fuels and the emission of polluting gases into the atmosphere, have gained great international prominence. With the advances of scientific community and the increase of the oil price in the beginning of the 1970s, the use of renewable, non-polluting and clean sources had a great investment by several countries. In this context, wind generation has stood out as one of the most promising, especially due to its economic viability and its fast technological development. Among the different topologies used in wind generation systems, the configuration developed for operation at variable speed is highlighted, which employs the doubly-fed induction generator (DFIG) associated with back-to-back electronic converter to control its operation. The main advantages of using DFIG include its greater efficiency in energy conversion, less mechanical rotor stress, independent control of active and reactive power limited to typical values of 30% of the rated power. On the other hand, it is known that, during the occurrence of a disturbance, such as an electrical fault, the rotor currents can reach high magnitudes in order to damage the rotor side converter. In addition, overvoltages in the DC link capacitor occur due to the loss of power transfer capacity on grid side converter. However, wind turbines may be required to main in operation even during a fault, in addition to contributing the restoration of voltage... (Complete abstract click electronic access below) / Mestre

The purpose of this study is to provide a historiographical and musical analysis examining the jazz ride cymbal pattern, from its inception on woodblock, small accessory cymbals, hand cymbal mechanisms and brushes through what becomes known as the modern-day ride cymbal pattern. This research examines a wide array of drummers and bandleaders, with the objective of identifying the earliest recordings of this important addition to jazz drumming, and popular music history while analyzing the ride cymbal pattern's evolution through definitive recordings. The study begins with the earliest known recordings that clearly display the pattern as it is played on any of the instruments mentioned above. The research concludes with the jam sessions of the early 1940s at Minton's Playhouse, where the pioneer of bebop drumming, Kenny Clarke, experimented with altering the pattern. At this point, the pattern reach its final level of maturity and has since experienced no subsequent major modification. The historical and geographical analysis uses relevant literature from the field of jazz history in order to interpret and evaluate the impact of the the overall trajectory of the music and players. By surveying newspaper and magazine articles, archival interviews, and photographic sources, combined with audio and film analysis, it is clear that drummers navigated a path to the maturation of the pattern.

As new requirements for grid connected generators were implemented, the requirements for evaluating the Fault Ride Through capabilities of the generators became stricter. When refurbishing a power unit, proof that the power unit meet the requirements must be submitted to the authorities. Performing simulations of the Fault Ride Through of a production unit is an extensive process and requires advanced simulation models and tools. Therefore, the need for a simplified tool for estimating the Fault Ride Through capability arose, which is what the project produced. Also, knowledge of which production module characteristics (such as the generator parameters, transformer and excitation system) have the largest effect on the Fault Ride Through time, would also be beneficial. Through the creation of Simulink simulation models of two hydropower stations and a sensitivity analysis of station parameters, the relative effect of the parameters on the Fault Ride Through time is estimated and implemented into a time independent Fault Ride Through time estimation tool, based on the Equal Area criterion. The purpose of the time-independent Fault Ride Through time estimation tool is to provide an insight into the approximate transient stability of the hydropower station and which parameters affect the performance the most. Simulations show that the transient reactance of the generator, the generator inertia, the transient time constant and the transformer inductance have the largest effect on the Fault Ride Through capability. The results show that a simplified tool cannot estimate the Fault Ride Through as accurately as a time-domain simulation model can.

A growing body of international research on urban transport shows that women from all over the world are experiencing safety issues within today’s transport systems. Furthermore, these reports shed light on and discuss how gender bias within the transport sector contributes to this problem. To design future mobility services that everyone will use and enjoy, it is thus important to understand women’s travel needs and to involve a diverse group of users in the development process. With a vision of shaping mobility for a sustainable future NationalElectric Vehicles Sweden (NEVS) is developing a mobility solution consisting of connected, autonomous, and electrified vehicles designed and optimized for shared mobility within city environments. To address this issue in NEVS service this thesis applied an exploitative research approach to examining factors that affect women’s willingness to share rides with others(potential strangers) in a context where there is no driver physically present. The methodology, inspired by the ’Design Thinking’ framework consisted of two main phases:(I) Problem definition and (II) Concept development. To understand women’s safety issues within today’s transport system and frame the design challenge an extensive literature study covering the topics of women’s safety in public transport, technology acceptance, trust, and human-centered design was conducted. To further define user needs and encourage the end-users to take an active role in co-designing solutions for themselves two focus group workshops were held. The initial research and the results from the workshops further formed the basis for the subsequent Concept Development phase. A need for control over the shared travel situation revealed by the participants’ great demand for information led this phase to examine passengers' needs in relation to an In-Vehicle Information System (IVIS). Two prototypes were developed and further tested together with users to evaluate the proposed solutions. The results showed that the anthropomorphic system features used to create a more human-like interaction had a positive impact on the participants’ overall user experience and their perceived safety during a ’shared ride’ scenario. Having a female voice communicating system information made the participants feel less nervous, more comfortable, and more secure compared to when the same information was communicated solely by a visual interface. Other factors that had a major impact on the user experience in general and the perceived security were perceived Ease of Use (PEOU) and freedom of choice. The results showed how not understanding how to interact with the vehicle’s physical features had a negative impact on perceived safety while freedom of choice such as being able to book a specific seat in the vehicle is indicated to have a positive impact on people’s willingness to share their journey with a stranger.