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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Návrh webové aplikace pro místenkový rezervační systém / Design and implementation of the seat tickets reservation system

Sedláček, Tomáš January 2013 (has links)
The topic of this master thesis is the design and development of the seat ticket reservation web application. Developed application should be useful for organizers of various cultural and sport events and should help them to manage ticket reservations agenda. Application should be useful for visitors of these events too. Visitors will be able to easily choose the preferred seats and complete the reservation within the application. The evaluation of existing tools designated for seat reservations management is the important part of this master thesis. According to the previous evaluation, the author's own experience and consultations with several organizers of public events, functionality requirements of the web application are specified. The acting roles are also defined and the most important use cases are stated for them. Web application of the seat reservation system is programmed using the latest web technologies such as PHP, Javascript, CSS3 and is based on the Nette PHP framework. The resulting web application is publicly accessible at http://demo.e mistenka.cz.
42

Car seat design and human-body modelling for rear impact whiplash mitigation

Himmetoglu, Selcuk January 2008 (has links)
Whiplash is a neck injury caused by the sudden differential movement between the head and torso. Whiplash injuries are most commonly reported as a consequence of rear impacts in car accidents. They are regarded as minor injuries, but can still lead to long-term disablement and discomfort in the neck. Whiplash injuries can be mitigated by better car seat designs. For this purpose, head restraint geometry must be improved first, and then the dynamic performance of the whole seat must be assessed at all crash seventies. A biofidelic human-body model is a key requirement in designing whiplash mitigating car seats. This thesis presents the development of a 50th percentile male multi-body human model and several energy absorbing car seat designs. The human-body model is specifically designed for rear impact and validated using the responses of seven volunteers from Japanese Automobile Research Institute (JARI) sled tests, which were performed at an impact speed of 8 kph with a rigid seat and without head restraint and seat belt. A generic multi-body car seat model is also developed to implement various seatback and recliner properties, anti-whiplash devices (A WDs) and head restraints. Using the same driving posture and the rigid seat in the JARI sled tests as the basic configuration, several anti-whiplash seats are designed to allow different types of motion for the seatback and seat-pan. The major findings of this research are: -The human-body model simulates the effects of muscle contraction and its overall response is superior in comparison to the currently used models and dummies. -A criterion called the S-shape index (SSI) is developed based on the intervertebral angles of the upper and lower cervical spine. -The car seat design concepts are able to control and use crash energy effectively with the aid of anti-whiplash devices for a wide range of crash seventies. -In order to reduce whiplash injury risk, this study advocates energy absorbing car seats which can also provide head restraint contact as early as possible.
43

Influência da temperatura, velocidade e força no desgaste e no coeficiente de atrito de materiais para válvulas e sedes de válvulas de motores flex-fuel. / Effect temperature, frequency and load in the wear and coefficient of friction for valves and valve seats materials of flex-fuel engines.

Zuleta Durango, Deisson Alexander 29 September 2016 (has links)
Na maioria dos equipamentos mecânicos há movimento relativo entre componentes, e como resultado desse deslizamento relativo, as forças de atrito na superfície geram deformação plástica e/ou remoção de massa (ou volume) do material. Nos motores de combustão interna a geração da potência é realizada pela transformação da energia química em calor por meio da combustão do combustível com o ar, gerando o movimento alternativo de mecanismos (pistões, biela, virabrequim). Já no caso dos motores flex-fuel, o etanol como combustível aumenta a potência, levando a maiores carregamentos termomecânicos e, consequentemente, tribológicos nos seus componentes. Um dos sistemas do motor mais afetado pela mudança no combustível é o par válvula-sede, motivo pelo qual é necessário investigar os mecanismos de desgaste, os efeitos dos parâmetros de operação no comportamento frente ao atrito, e escolher apropriadamente pares deslizantes de materiais que apresentem baixas perdas de massa (taxas de desgaste) e coeficientes de atrito. Ensaios do tipo reciprocating tinham sido empregados para realizar estudos tribológicos de materiais de válvulas e com tratamentos superficiais. As condições de ensaio mais representativas são de operação do motor. Portanto, a seleção de parâmetros como carga, velocidade e temperatura não é fácil: para alguns equipamentos de teste, as variáveis não são independentes. Além disso, devido à complexidade do sistema tribológico, a interação entre as variáveis afeta os resultados. O objetivo deste trabalho de pesquisa foi dividido em duas frentes. A primeira, analisar isoladamente o efeito da temperatura, força normal e velocidade no coeficiente de atrito e no desgaste. O tribômetro SRV-4 do tipo reciprocating foi usado com uma esfera de aço AISI 52100 e distintos materiais de disco (aços e ligas intermetálicas sinterizadas de Nb). A segunda parte consistiu na caracterização dos mecanismos de desgaste de válvulas e sedes de motores distintos, após diferentes tipos de ensaios (dinamômetro e campo em veiculo). O coeficiente de atrito (?) e a perda de massa foram medidos para determinar o desempenho tribológico dos sistemas estudados. Além disso, as superfícies das marcas de desgaste tanto no disco quanto na esfera, assim como das válvulas e sedes foram analisadas por microscopia óptica (MO), microscopia eletrônica de varredura (MEV) com espectroscopia de energia dispersiva de raios-X (EDS) e espectroscopia Raman. Para as distintas ligas intermetálicas de Nb ensaiadas com esfera de aço AISI 52100, encontrou-se que os mecanismos de desgaste nas superfícies após uma análise de MEV-EDS foram particularmente abrasão, adesão e oxidação. Já no caso dos motores que foram avaliados, muitos dos danos observados estavam presentes em ambas as válvulas e sedes de admissão e escape; no entanto, a oxidação ocorreu apenas nas válvulas de escape, provavelmente produzido pela alta temperatura durante a operação do motor. / In most of the mechanical assemblies there is relative motion between components, and as a result of this relative sliding action, frictional forces on the sliding surface result in removal or displacement of mass (or volume) of the material. The power generation of internal combustion engines comes from chemical energy transformation into heat through air fuel combustion with further expansion of gases generating the reciprocating movement of power cell (pistons, rod and crankshaft). For flex fuel engines, the ethanol increases power, leading to higher thermo-mechanical forces and consequently higher friction between its components. The valve/valve seat pair is one of the most affected system due to this change, leading to the need of more accurate analysis of its wear mechanisms, its operating parameters effects and his behavior regarding the friction so making possible to choose properly materials with lower mass loss (wear rate) and coefficient of friction. Reciprocating tests had been used to tribological studies of valve materials with surface treatment purpose. The most important test boundary conditions are the engine operating conditions. Therefore, the load, speed and temperature parameters definition is not easy since for some test equipment those variables are not independent. Besides due to tribological system complexity the variable interaction affects its results. The present research goal was divided in two groups. The first one analyzes the normal force, frequency and temperature effect on friction coefficient and wear, independently of each other. It was used a SRV-4 reciprocating tribometer with a sphere (AISI 52100 steel) against several disc materials (steel and sintered intermetallic alloys of Nb). The second one consisted in the characterization of wear mechanisms of valve/valve seat from different engines that were submitted to different test (engine dynamometer test bench and vehicle). The coefficient of friction (?) and mass loss were measured in order to define the studied systems tribological performance. Besides the both disc and sphere wear scars such as valve/valve seat were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy of X-ray (EDS) and Raman spectroscopy. For the tested intermetallic alloys of Nb with AISI 52100 sphere it was found the following wear mechanisms after SEM-EDS analyses: abrasion, adhesion and oxidation. In the case of the evaluated engines, several damages were observed in both intake and exhaust valves/valve seats; however, the oxidation occurred only on exhaust valves, probably due to high operating temperature.
44

Influência da temperatura, velocidade e força no desgaste e no coeficiente de atrito de materiais para válvulas e sedes de válvulas de motores flex-fuel. / Effect temperature, frequency and load in the wear and coefficient of friction for valves and valve seats materials of flex-fuel engines.

Deisson Alexander Zuleta Durango 29 September 2016 (has links)
Na maioria dos equipamentos mecânicos há movimento relativo entre componentes, e como resultado desse deslizamento relativo, as forças de atrito na superfície geram deformação plástica e/ou remoção de massa (ou volume) do material. Nos motores de combustão interna a geração da potência é realizada pela transformação da energia química em calor por meio da combustão do combustível com o ar, gerando o movimento alternativo de mecanismos (pistões, biela, virabrequim). Já no caso dos motores flex-fuel, o etanol como combustível aumenta a potência, levando a maiores carregamentos termomecânicos e, consequentemente, tribológicos nos seus componentes. Um dos sistemas do motor mais afetado pela mudança no combustível é o par válvula-sede, motivo pelo qual é necessário investigar os mecanismos de desgaste, os efeitos dos parâmetros de operação no comportamento frente ao atrito, e escolher apropriadamente pares deslizantes de materiais que apresentem baixas perdas de massa (taxas de desgaste) e coeficientes de atrito. Ensaios do tipo reciprocating tinham sido empregados para realizar estudos tribológicos de materiais de válvulas e com tratamentos superficiais. As condições de ensaio mais representativas são de operação do motor. Portanto, a seleção de parâmetros como carga, velocidade e temperatura não é fácil: para alguns equipamentos de teste, as variáveis não são independentes. Além disso, devido à complexidade do sistema tribológico, a interação entre as variáveis afeta os resultados. O objetivo deste trabalho de pesquisa foi dividido em duas frentes. A primeira, analisar isoladamente o efeito da temperatura, força normal e velocidade no coeficiente de atrito e no desgaste. O tribômetro SRV-4 do tipo reciprocating foi usado com uma esfera de aço AISI 52100 e distintos materiais de disco (aços e ligas intermetálicas sinterizadas de Nb). A segunda parte consistiu na caracterização dos mecanismos de desgaste de válvulas e sedes de motores distintos, após diferentes tipos de ensaios (dinamômetro e campo em veiculo). O coeficiente de atrito (?) e a perda de massa foram medidos para determinar o desempenho tribológico dos sistemas estudados. Além disso, as superfícies das marcas de desgaste tanto no disco quanto na esfera, assim como das válvulas e sedes foram analisadas por microscopia óptica (MO), microscopia eletrônica de varredura (MEV) com espectroscopia de energia dispersiva de raios-X (EDS) e espectroscopia Raman. Para as distintas ligas intermetálicas de Nb ensaiadas com esfera de aço AISI 52100, encontrou-se que os mecanismos de desgaste nas superfícies após uma análise de MEV-EDS foram particularmente abrasão, adesão e oxidação. Já no caso dos motores que foram avaliados, muitos dos danos observados estavam presentes em ambas as válvulas e sedes de admissão e escape; no entanto, a oxidação ocorreu apenas nas válvulas de escape, provavelmente produzido pela alta temperatura durante a operação do motor. / In most of the mechanical assemblies there is relative motion between components, and as a result of this relative sliding action, frictional forces on the sliding surface result in removal or displacement of mass (or volume) of the material. The power generation of internal combustion engines comes from chemical energy transformation into heat through air fuel combustion with further expansion of gases generating the reciprocating movement of power cell (pistons, rod and crankshaft). For flex fuel engines, the ethanol increases power, leading to higher thermo-mechanical forces and consequently higher friction between its components. The valve/valve seat pair is one of the most affected system due to this change, leading to the need of more accurate analysis of its wear mechanisms, its operating parameters effects and his behavior regarding the friction so making possible to choose properly materials with lower mass loss (wear rate) and coefficient of friction. Reciprocating tests had been used to tribological studies of valve materials with surface treatment purpose. The most important test boundary conditions are the engine operating conditions. Therefore, the load, speed and temperature parameters definition is not easy since for some test equipment those variables are not independent. Besides due to tribological system complexity the variable interaction affects its results. The present research goal was divided in two groups. The first one analyzes the normal force, frequency and temperature effect on friction coefficient and wear, independently of each other. It was used a SRV-4 reciprocating tribometer with a sphere (AISI 52100 steel) against several disc materials (steel and sintered intermetallic alloys of Nb). The second one consisted in the characterization of wear mechanisms of valve/valve seat from different engines that were submitted to different test (engine dynamometer test bench and vehicle). The coefficient of friction (?) and mass loss were measured in order to define the studied systems tribological performance. Besides the both disc and sphere wear scars such as valve/valve seat were analyzed using optical microscopy (OM), scanning electron microscopy (SEM) with energy dispersive spectroscopy of X-ray (EDS) and Raman spectroscopy. For the tested intermetallic alloys of Nb with AISI 52100 sphere it was found the following wear mechanisms after SEM-EDS analyses: abrasion, adhesion and oxidation. In the case of the evaluated engines, several damages were observed in both intake and exhaust valves/valve seats; however, the oxidation occurred only on exhaust valves, probably due to high operating temperature.
45

Méthode d'évaluation des systèmes de retenue des enfants dans un environnement automobile / Child restraint systems assessment methodology in an automotive context

Le Tellier, Bérenger 11 April 2017 (has links)
Suite à l’évolution de la réglementation relative aux dispositifs de retenue pour enfants en juillet 2013, une campagne d’évaluation expérimentale a permis de constater que la situation des plus jeunes impliqués dans un choc latéral était particulièrement critique. Pour y remédier, une méthodologie originale a été développée dans le but de dimensionner les matériaux d’absorption d’énergie « idéaux » à intégrer aux sièges-auto au niveau des zones d’impact de la tête, de l’épaule et du bassin. Une étude paramétrique basée sur ce concept a alors consisté à piloter la retenue de ces trois segments corporels dans le but de minimiser, soit les critères réglementaires (mannequins Q0 et Q1), soit les critères biomécaniques (modèle hybride Q0-6WOC). Les recommandations issues de cette étude ont ensuite été appliquées à un dispositif de retenue existant afin de l’optimiser en choc latéral. Après avoir vérifié que les valeurs d’accélération linéaire résultante de la tête et de HPC étaient bien inférieures aux seuils imposés par la réglementation, un modèle par Eléments Finis (EF) du siège-auto optimisé a été développé puis validé en situation dynamique. Finalement, après couplage de ce modèle EF du dispositif de retenue optimisé avec le modèle hybride Q0-6WOC, il a été montré que les résultats de simulation numérique en choc latéral étaient deux fois plus faibles que ceux obtenus avec le dispositif de retenue de référence. / Following changes in Child Restraint System (CRS) regulation in July 2013, an experimental CRS evaluation campaign has been conducted. Then, it has been noticed that the situation amongst the youngest involved in side impact was particularly critical. An original methodology has been therefore developed in order to define the “best” energy absorption materials to use in child seats for head, shoulder and pelvis areas. A parametric study in which the restraint of each body segments was independently piloted has then been conducted. The aim was to minimize either regulatory criteria of Q0 and Q1 dummies, or biomechanical criteria based on Q0-6WOC hybrid model. Those recommendations have thereafter been applied to improve an existing child restraint system under side impact. First, it has been checked that resultant linear acceleration of the head and HPC criteria were below regulation limits. Second, Finite Element (FE) model of the optimized car seat has been created and validated in several dynamical steps. Third, both reference child restraint system and optimized child seat has been evaluated in side impact with Q0-6WOC hybrid model. Finally, it has been showed that technical changes helped to cut in half the biomechanical results.
46

[en] ERGONOMIC AND KINESIOLOGIC EVALUATION ON LOW BACK CONSTRAINTS IN SITTING POSITION DURING LONG DISTANCE FLIGHTS / [pt] AVALIAÇÃO ERGONÔMICA E CINESIOLÓGICA DOS CONSTRANGIMENTOS MÚSCULO ESQUELÉTICOS DA REGIÃO SACRO LOMBAR NA POSTURA SENTADA EM VIAGENS AÉREAS LONGAS

MARIANA HUET DE SALVO SOUZA 28 June 2004 (has links)
[pt] A imobilidade na postura sentada reclinada e as limitações no espaço da poltrona de viagens aéreas longas, somadas aos efeitos da pressão do peso do corpo sobre os tecidos levam o passageiro a uma acomodação na busca de conforto. Os constrangimentos músculo-esqueléticos conseqüentes podem provocar dores e desconforto nos usuários. Para estudar as causas dos constrangimentos foram vistos os dados sobre a postura humana, com ênfase na região sacro-lombar, assim como indicações de ergonomistas sobre cadeiras e as prioridades da aviação comercial. Os métodos usados na observação foram a revisão bibliográfica em autores de ergonomia, anatomia, cinesiologia. A assessoria de informante qualificado em interiores de aviões juntou-se à consulta a revistas especializadas na área da aviação comercial. Os resultados obtidos através da análise dos dados do questionário (n=115) confirmam o desconforto sentido pelos passageiros de viagens aéreas longas em regiões como pescoço (64,3 por cento), lombo-sacra (48,7 por cento) e pés (59,1 por cento). Inadequações como a largura do assento (58,3 por cento), o espaço para as pernas (50,4 por cento), o apoio do pescoço (47,8 por cento), e o apoio lombar (37,4 por cento) foram apontadas por estes usuários. As conclusões confirmam a hipótese O espaço limitado das poltronas aéreas e as conseqüentes posições assumidas pelos passageiros durante viagens aéreas longas acarretam constrangimentos posturais músculo-esqueléticos, e trazem como conseqüência desconforto e dores no pescoço, região lombar e pés, dormência e dores irradiadas nos usuários. As recomendações foram em relação à ergonomia da postura sentada para o apoio lombar, assento e posições de membros inferiores. Desdobramentos sugeridos foram a observação de passageiros durante a viagem, estudos sobre o sistema circulatório dos membros inferiores, constrangimentos posturais na região cervical e posterior da pelve. / [en] The lack of mobility in reclined sitting posture, the space limitations in seats in long distance flights along with the relief of pressure lead the passenger to scoop his hip forwards or to twist it. Consequent muscular and skeletal postural constraints may cause discomfort and pain on users. Searching for the reasons of constraints, human posture studies, ergonomics recommendations on chairs and aicraft priorities were seen. The study methods employed were a literature review on Ergonomics, Anatomies and Kinesiologists, aircraft interiors qualified informant and aircraft interiors specialized revues. A questionnaire was submitted to long flight passengers to search for body discomfort and inadequacies on seats. Data analysis (n=115) showed discomfort on neck region (63,3 percent), feet (59,1 percent) and low back (48,7 percent). Inadequacies on seats design such as width (58,3 percent), room for legs (50,4 percent), neck support (47,8 percent) and lumbar support (37,4 percent) were pointed by passengers. The hypothesis Lack of room in aircraft seats and the positions assumed during long distance flights cause postural constraints that lead to discomfort and pain on neck, low back and feet, numbness and irradiation on users was confirmed. Recommendations on lumbar support possibilities, height of seat and lower limbs positions were made. Suggestions like further observation of flying passengers, circulatory system and postural constraints on cervical and pelvic region were proposed.
47

Optimalizace sacího potrubí zážehového motoru / Optimalization of Intake Manifold for SI Engine

Foral, Martin January 2009 (has links)
The work deals with design solutions to the intake manifold modern contemporary internal combustion engines. Then describes the types of flow and structural design of ports, including the intake of their basic properties. The thesis also compare the results of the analysis and design optimization based on simulation of flow inlet port and measure the actual inlet port.
48

Návrh zařízení pro testování a měření ovládacích sil automobilových sedadel / Design of equipment for testing and measurement control forces car seats

Vincenc, Josef January 2013 (has links)
The Master’s thesis deals with development of universal equipment for testing and measurement operating forces of car seats. It describes tests applied on car seats and shows a few examples of equipment for testing. The design part of the thesis deals with development of multipurpose testing equipment using of Modular Function Deployment™ approach. The design of the equipment is done in 5 steps according to mentioned approach. The final part of the thesis includes a risk analysis of the new device and conclusion.
49

Převislé mandáty. Problematické specifikum německého volebního systému / Overhang seats. A controversial particularity of the German electoral system

Jágr, Jan January 2011 (has links)
The objective of the thesis is a detailed analysis of overhang seats, the peculiarity of the German electoral system. The theoretical part of this thesis focuses on research of the electoral systems and their political consequences. The second chapter devoted to the German electoral system explains his mechanical functioning and discuses his influence on the degree of proportionality and the party system. The analytical part tries to clear the phenomenon of overhang seats, his origins by means of testing presented variables using the electoral results data from 1990 - 2009. The current electoral reform is also discussed.
50

Investigation of Pediatric Seat Belt Fit on Belt-Positioning Booster Seats (BPBs) and the Implications for Belt Interaction and Dynamic Outcomes during Motor Vehicle Crashes

Baker, Gretchen Hess 12 September 2022 (has links)
No description available.

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