• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 76
  • 56
  • 20
  • 7
  • 5
  • 4
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 198
  • 59
  • 54
  • 43
  • 35
  • 34
  • 26
  • 23
  • 20
  • 20
  • 20
  • 19
  • 17
  • 16
  • 16
  • 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.
71

Valores de referência e confiabilidade de testes clínicos para avaliação funcional lombopélvica / Reference values and reliability for tests of lumbopelvic functional assessment

Isadora Orlando de Oliveira 16 September 2016 (has links)
Introdução: Força, resistência e atividade muscular são uma área importante de pesquisa e avaliação contribuindo para um melhor entendimento de aspectos musculoesqueléticos de mecanismos de dor e lesão. No entanto, a utilização de testes que avaliem a região lombopélvica ainda é controversa, pois apesar de muitos testes clínicos estarem disponíveis na literatura, ainda não estão estabelecidos quais os mais confiáveis na prática clínica. Objetivos: Estabelecer valores de referência, determinar confiabilidade intra e interexaminador e as medidas de erro de um conjunto de testes clínicos que avaliam a região lombopélvica em indivíduos assintomáticos de diferentes gêneros, faixas etárias e níveis de atividade física. Materiais e Métodos: Para os valores de referência, 152 indivíduos (79 homens, 73 mulheres) estratificados por gênero, faixa etária e nível de atividade física realizaram um conjunto de nove testes clínicos: força isométrica máxima de abdutores, extensores, flexores e rotadores laterais de quadril, resistência nas posições de ponte lateral, ponte frontal, flexores e extensores lombares e atividade muscular da região lombopélvica. Para a confiabilidade, 33 indivíduos foram avaliados por dois examinadores em um intervalo de 3 a 7 dias, onde realizaram aleatoriamente o mesmo conjunto de testes. As medidas de confiabilidade foram avaliadas pelo Coeficiente de Correlação Interclasse (CCI2,1) e as medidas de erro definidas pelo Erro Padrão da Medida (EPM) e pela Mínima Mudança Detectável (MMD). Resultados: Foram observadas diferenças significativas (p<0.05) nos testes clínicos para as variáveis: gênero, faixa etária e nível de atividade física e estabelecidos valores de referência para cada grupo. Todos os testes apresentaram valores de confiabilidade excelente com CCI (IC 95%) maior que 0.8 para as confiabilidades intra e interexaminador; os valores da MMD foram superiores à média do EPM em todos os testes. Conclusão: Os resultados do presente estudo apontam valores de referência que contribuem com o estabelecimento de referências para auxiliar na tomada de decisões clínicas. Além disso, este conjunto de 10 testes apresentou confiabilidade intra e interexaminador bem como valores de EPM e MMD, confirmando a possibilidade de seu uso na prática clínica. / Background: The assessment of the lumbopelvic region is useful for many musculoskeletal dysfunctions. Several clinical tests are commonly used to assess this region, however, reference values for clinical assessments and results concerning method, reliability and error measurements of these tests have not been reported. Objectives: To establish reference values and to determine intra and interrater reliability, standard error of measurement (SEM) and minimum detectable change (MDC) of a set of clinical tests used for assessing the lumbopelvic region in asymptomatic volunteers of different gender, age groups and physical activity levels. Methods: For reference values, 152 subjects (79 men, 73 women) divided by gender, age group and physical activity levels, performed nine clinical tests: Maximum voluntary isometric strength of hip abductors, extensors, flexors and lateral rotators, transversus abdominis(TrA) muscle activity (using a Pressure Biofeedback Unit), prone and side bridges, trunk flexor and extensor endurance tests. To measure reliability, 33 individuals performed the same set of tests, in random order within a week period. Intrarater and interrater analysis were assessed using the Intraclass Correlation Coefficient (ICC) and the error measurements were defined by using the SEM and the MDC. Results: Reference values were established for each group and our results showed significant (p<0.05) differences concerning gender, age group and physical activity levels in clinical tests. In general, strength differences were related to gender and physical activity levels and endurance results could be related to interactions between gender, age group and physical activity levels. All tests presented good reliability indices with an ICC (95%CI) higher than 0.8 for the intrarater and interrater reliability; MDC values were greater than mean of SEM in all tests, confirming its usage for clinical practice assessments. Conclusion: Reference values are necessary to help clinicians in the evaluation of subjects and these results can contribute for clinical practice in providing clinical training targets. Also, this set of tests presented good intra and interrater reliability measures of strength, endurance and TrA muscle activity test as well as SEM and MDC values, confirming its use for assessing the lumbopelvic region.
72

Valores de referência e confiabilidade de testes clínicos para avaliação funcional lombopélvica / Reference values and reliability for tests of lumbopelvic functional assessment

Oliveira, Isadora Orlando de 16 September 2016 (has links)
Introdução: Força, resistência e atividade muscular são uma área importante de pesquisa e avaliação contribuindo para um melhor entendimento de aspectos musculoesqueléticos de mecanismos de dor e lesão. No entanto, a utilização de testes que avaliem a região lombopélvica ainda é controversa, pois apesar de muitos testes clínicos estarem disponíveis na literatura, ainda não estão estabelecidos quais os mais confiáveis na prática clínica. Objetivos: Estabelecer valores de referência, determinar confiabilidade intra e interexaminador e as medidas de erro de um conjunto de testes clínicos que avaliam a região lombopélvica em indivíduos assintomáticos de diferentes gêneros, faixas etárias e níveis de atividade física. Materiais e Métodos: Para os valores de referência, 152 indivíduos (79 homens, 73 mulheres) estratificados por gênero, faixa etária e nível de atividade física realizaram um conjunto de nove testes clínicos: força isométrica máxima de abdutores, extensores, flexores e rotadores laterais de quadril, resistência nas posições de ponte lateral, ponte frontal, flexores e extensores lombares e atividade muscular da região lombopélvica. Para a confiabilidade, 33 indivíduos foram avaliados por dois examinadores em um intervalo de 3 a 7 dias, onde realizaram aleatoriamente o mesmo conjunto de testes. As medidas de confiabilidade foram avaliadas pelo Coeficiente de Correlação Interclasse (CCI2,1) e as medidas de erro definidas pelo Erro Padrão da Medida (EPM) e pela Mínima Mudança Detectável (MMD). Resultados: Foram observadas diferenças significativas (p<0.05) nos testes clínicos para as variáveis: gênero, faixa etária e nível de atividade física e estabelecidos valores de referência para cada grupo. Todos os testes apresentaram valores de confiabilidade excelente com CCI (IC 95%) maior que 0.8 para as confiabilidades intra e interexaminador; os valores da MMD foram superiores à média do EPM em todos os testes. Conclusão: Os resultados do presente estudo apontam valores de referência que contribuem com o estabelecimento de referências para auxiliar na tomada de decisões clínicas. Além disso, este conjunto de 10 testes apresentou confiabilidade intra e interexaminador bem como valores de EPM e MMD, confirmando a possibilidade de seu uso na prática clínica. / Background: The assessment of the lumbopelvic region is useful for many musculoskeletal dysfunctions. Several clinical tests are commonly used to assess this region, however, reference values for clinical assessments and results concerning method, reliability and error measurements of these tests have not been reported. Objectives: To establish reference values and to determine intra and interrater reliability, standard error of measurement (SEM) and minimum detectable change (MDC) of a set of clinical tests used for assessing the lumbopelvic region in asymptomatic volunteers of different gender, age groups and physical activity levels. Methods: For reference values, 152 subjects (79 men, 73 women) divided by gender, age group and physical activity levels, performed nine clinical tests: Maximum voluntary isometric strength of hip abductors, extensors, flexors and lateral rotators, transversus abdominis(TrA) muscle activity (using a Pressure Biofeedback Unit), prone and side bridges, trunk flexor and extensor endurance tests. To measure reliability, 33 individuals performed the same set of tests, in random order within a week period. Intrarater and interrater analysis were assessed using the Intraclass Correlation Coefficient (ICC) and the error measurements were defined by using the SEM and the MDC. Results: Reference values were established for each group and our results showed significant (p<0.05) differences concerning gender, age group and physical activity levels in clinical tests. In general, strength differences were related to gender and physical activity levels and endurance results could be related to interactions between gender, age group and physical activity levels. All tests presented good reliability indices with an ICC (95%CI) higher than 0.8 for the intrarater and interrater reliability; MDC values were greater than mean of SEM in all tests, confirming its usage for clinical practice assessments. Conclusion: Reference values are necessary to help clinicians in the evaluation of subjects and these results can contribute for clinical practice in providing clinical training targets. Also, this set of tests presented good intra and interrater reliability measures of strength, endurance and TrA muscle activity test as well as SEM and MDC values, confirming its use for assessing the lumbopelvic region.
73

Development of a 2-Mode AWD E-REV powertrain and real-time optimization-based control system

Waldner, Jeffrey James 24 October 2011 (has links)
Increasing environmental, economic, and political concerns regarding the consumption of fossil fuels have highlighted the need for more efficient and alternative energy solutions. Hybrid electric vehicles represent a near-term opportunity for reducing liquid fossil fuel consumption and green-house gas emissions in the transportation industry, and as a result, many automotive manufacturers have invested heavily in hybrid vehicle development. The increased complexity of hybrid electric vehicles over standard internal combustion engine-powered vehicles has subsequently placed significant emphasis on development of advanced control methods geared towards efficient energy management. Real-time optimization-based methods represent the current state-of-the-art in terms of hybrid vehicle control and energy management. This thesis summarizes the development of an optimization-based real-time control system – which determines the optimal instantaneous system operating point, including gear, traction split between front rear axles, and engine speed and torque – and its application to an all-wheel drive extended-range electric vehicle that uses a General Motor’s front-wheel drive 2-Mode electronic continuously variable transmission and an additional rear traction motor. The real-time control system was developed and validated using a plant model and preliminarily tested in the vehicle using a four-wheel drive chassis dynamometer. Results of simulation and in-vehicle testing demonstrate engine operation focused on high-efficiency operating regions and minimal use of the rear traction motor. Further testing revealed that a rule-based traction split system may be sufficient to replace the optimization-based traction split determination, and that the limited rear traction motor use was not a function of the motor itself, but rather an inherent result of the selected architecture. / Graduate
74

Analysis of heat dissipation from railway and automotive friction brakes

Voller, Gordon Paul January 2003 (has links)
The thesis presents research into the understanding and improvement of heat dissipation from friction brakes. The investigations involved two brake types, considered to be the most thermally loaded and therefore most challenging; axle mounted high speed railway and commercial vehicle disc brakes. All three modes of heat transfer (conduction, convection and radiation) and airflow characteristics have been analysed experimentally and theoretically in order to increase the understanding of heat dissipation. Despite the very practical aspects of this research, a 'generic heat transfer approach' was applied, enabling wider engineering applications of the results. Experimental analyses conducted on a specially developed Spin Rig allowed measurements of cooling and airflow characteristics for different designs. Methodologies have been developed to determine thermal contact resistance, heat transfer coefficients, emissivity and aerodynamic (pumping) losses. Established values and relationships compared very favourably with theoretical work. Analytical, FE and CFD analyses were employed to further investigate design variations and perform sensitivity studies. Inertia dynamometer route simulations provided disc temperatures for validation of the overall work. Recommendations have been made for optimising heat dissipation, by proposing practically acceptable and economically viable design solutions. A proposed ventilated disc design efficiency ratio allows large, high speed ventilated disc designs, to be efficiently and accurately evaluated and compared, providing a valuable disc design optimisation tool. The determination of the methodologies, parameters and functions defining cooling characteristics, enable heat dissipation to be predicted confidently and accurately for brakes and other engineering assemblies at early design stages.
75

Hand function in children and in persons with neurological disorders : aspects of movement control and evaluation of measurements /

Svensson, Elisabeth, January 2009 (has links)
Diss. (sammanfattning) Umeå : Umeå universitet, 2009. / Härtill 4 uppsatser.
76

Hand function in children and in persons with neurological disorders aspects of movement control and evaluation of measurements /

Svensson, Elisabeth, January 2009 (has links)
Diss. (sammanfattning) Umeå : Univ., 2009.
77

Desempenho e emissões de motor agrícola ciclo diesel utilizando diferentes combustíveis / Performance and emissions for agricultural cycle diesel engine using different fuel's

Perin, Gismael Francisco 25 July 2014 (has links)
The behavior of the agricultural cycle diesel engine when changes the fuel type and operating mode, must be known so that we can identify the best fuel resulting in better performance at lower emissions. However, when using particular type of fuel, with or without blends, the motor parameters such as torque, power and consumption, and emissions of gases changes. Therefore, the aim of this work was to verify the influence of the types of fuels for performance parameters of the agricultural cycle diesel engines and the emissions generated by burning fossil fuels. For this first experiment was conducted to determine the ideal number of repetitions and the warming s time the engine to perform the experiments proposed by objectives. Eighteen repeticions were conducted in 3 groups corresponding to warm times of 20, 60 and 100 minutes. To identify whether there was a significant difference between the warming s time was conducted the analysis of variance and the minimum number of repetitions required was identified by a lower rate of coefficient of variation. The experimental performance of the engine with different fuels was performed using 11 fuel (Diesel S10, S500 diesel, biodiesel and its blends [5%, 10%, 15%, 20%, 50% and 100% concentration of biodiesel in diesel]). Outcome variables were assessed torque, power consumption and time specific consumption. Analysis of variance was performed and, if present difference, the data were subjected to the mean comparison test (Tukey p ≥ 0.05) and linear regression analysis. Emissions of O2, CO2, NO2, NO, CO and HC were analyzed. The fuels used were the same performance experiment with the same blends. The emissions test followed the methodology laid down in the NBR ISO 8174-4:2012, which indicates 8 modes of operation of the engine in three rotations. Analysis of variance was performed and, if present difference, the data were subjected to the mean comparison test (Tukey p � 0.05) and linear regression analysis. The results report that four were the number of repetitions for the test performance and that 20 minutes was the time of warming the engine. Both the type of fuel and the operating mode significantly alter the performance and emissions. There was a reduction of the maximum torque and maximum power and increased consumption and minimum specific consumption with increase of biodiesel in the blend. Emissions of NO2 and O2 increased with higher concentration of biodiesel in the blend. Emissions of CO2, opacity, NO, CO and HC were decreased as increasing the amount of biodiesel in the blend with mineral diesel. In all variables, except O2, there was a reduction in emissions decreased when the load applied in engine. The fuel reduced emissions and maintained performance, compared with commercial diesel fuel was Diesel S10 with 20% biodiesel. / O comportamento dos motores agrícolas ciclo Diesel quando altera-se o tipo de combústivel e o modo de operação, deve ser conhecido para que se possa identificar qual o melhor combustível que resulte em melhor desempenho e menor emissão de poluentes. Entretanto, quando se utiliza determinado tipo de combustível, com ou sem misturas, os parâmetros do motor como torque, potência e consumo, e as emissões de gases se alteram de maneira diferenciada. Portanto, o objetivo deste trabalho foi verificar a influência dos tipos de combustíveis nos parâmetros de desempenho dos motores agrícolas ciclo Diesel e nas emissões de gases gerados pela queima destes combustíveis. Para isto, primeiramente foi realizado um experimento para determinar o número de repetições ideal e o tempo de aquecimento do motor para realizar os experimentos propostos pelos objetivos. Foram realizados 18 repetições separadas em 3 grupos, correspondentes aos tempos de aquecimento de 20, 60 e 100 minutos. Para identificar se houve diferença significativa entre os tempos de aquecimento foi realizado a análise da variância e o número de repetições mínimo necessário foi identificado pelo menor índice de coeficiente de variação. O experimento de desempenho do motor com diferentes combustíveis foi realizado utilizando 11 combustíveis, (Diesel S10, diesel S500, biodiesel e suas misturas [5%, 10%, 15%, 20%, 50% e 100% de concentração de biodiesel no diesel]). As variáveis respostas avaliadas foram torque, potência, consumo horário e consumo específico. Foi realizado a análise da variância e, caso apresentasse diferença, os dados foram submetidos ao teste de comparação de médias (Tukey p� 0,05) e análise de regressão linear. Ainda foram analisadas as emissões de O2, CO2, opacidade, NO2, NO, CO e HC. Os combustíveis utilizados foram os mesmos do experimento de desempenho, com as mesmas misturas. O ensaio de emissões seguiu a metodologia prevista na Norma NBR ISO 8174-4:2012, que indica 8 modos de operação do motor em três rotações. Foi realizado a análise da variância e, caso apresentasse diferença, os dados foram submetidos ao teste de comparação de médias (Tukey p≥ 0,05) e análise de regressão linear. Os resultados informam que quatro foram o número de repetições para o ensaio de desempenho do motor e que 20 minutos foi o tempo de aquecimento do motor. Tanto o tipo de combustível quanto o modo de operação alteraram significativamente o desempenho e as emissões. Houve redução do torque máximo e da potência máxima e aumento do consumo horário e específico mínimo com incremento de biodiesel na mistura. As emissões de NO2 e O2 aumentaram com a maior concentração de biodiesel na mistura. Já as emissões de CO2, opacidade, NO, CO e HC reduziram conforme foi aumentado o teor de biodiesel na mistura com diesel mineral. Em todas as variáveis analisadas, com exceção do O2, ocorreu redução das emissões quando se diminuiu a carga aplicada no motor. O combustível que reduziu as emissões e manteve o desempenho, comparativamente com o diesel comercial, foi o Diesel S10 com 20% de biodiesel.
78

Etude de la découpe de matériau en feuille souple par lame vibrante / Experimental study on cutting flexible sheet material using an oscillating knife

Cosson-Coche, Quentin 06 March 2017 (has links)
De par la grande diversité de tissus existants, tous avec des caractéristiques mécaniques différentes, il n’y a que peu d’études portant sur la découpe de tissus textiles.Cette thèse s’intéresse à la découpe de textile en multi-plis par l’action d’une lame oscillante dans un contexte industriel.Dans cette étude, une machine de découpe industrielle est équipée de différents capteurs afin de pouvoir mesurer l’influence des efforts de coupe sur la qualité des pièces découpées. En utilisant cet équipement, il a été possible de contrôler les efforts de coupe pendant toute la durée d’une coupe rectiligne.Enfin, un modèle physique de ces efforts est proposé en prenant en compte différents paramètres comme la géométrie de la lame, les propriétés du matériau découpé et les différents paramètres de coupe. / Due to the wide variety of fabrics, all with different mechanical characteristics, there are few studies dealing with the question of cutting fabrics.In this thesis, we model the multi-ply cutting process using a reciprocating knife in an industrial context.In this study, a textile cutting machine is instrumented with different sensors, to measure the influence of cutting forces on the quality of the resulting profiles. Using this equipment, cutting forces can be analyzed experimentally while the fabric is being cut along a straight line.Next, a model of the physical phenomena of these forces is proposed, taking different parameters into account such as the geometry of the knife, the properties of the material being cut and the parameters of the cut.
79

The Effect of an Energy Drink on Acute Muscle Strength and Fatigue in Young Males

January 2012 (has links)
abstract: The popularization of energy drink use as a supplement to exercise is steadily increasing, especially among young adult males. However, the effects of energy drinks on muscular performance in young adults have yet to be clearly elucidated. Eight male subjects (mean age: 23.3 &plusmn; 4.3 yrs, height: 181.0 &plusmn; 5.3 cm, fat percent 17.8 &plusmn; 5.2%, and weight 85.3 &plusmn; 12.6 kg) completed this randomized double-blinded cross over study. The purpose of this study was to determine differences in acute muscular strength and endurance and Profile of Mood States (POMS) scores between three treatments (RockStar, sugar-free RockStar, and sugar-free caffeine-free Placebo). It was hypothesized that there would be no significant differences in acute peak torque and endurance of the knee extensors and flexors or on fatigue and vigor subscores from the POMS questionnaire. Each man was tested randomly at least 1 week apart. Diet and time of day were held constant across trials. Peak torque of knee extensors and flexors at 60, 180, 240 degress/second and fatigue index and total work were calculated by performing 50 repetitions at 240 degrees/second. There were no significant differences in peak torque, fatigue index, or total work measures or in subjective measures of fatigue or vigor from the POMS between the treatments. This study indicates that RockStar energy drinks have no acute ergogenic effects in young men performing isokinetic strength or endurance testing. / Dissertation/Thesis / M.S. Exercise and Wellness 2012
80

Komparace měřících senzorů Vernier se zaměřením na lékařství / Comparison of measurement Vernier sensors focused on medicine

WIMMER, Roman January 2017 (has links)
The diploma thesis describes selected Vernier sensors and demonstrates their utilization in schools. The selection of digital tools is focused on medial area. In particular, the thesis deals with the ECG, spirometer, and dynamometer sensors. In the theoretical part, the history of the Vernier company is presented and the Vernier system and its benefits are discussed with special regard to the workflow from preparation phase to the process of measuring which can be used in classrooms. The research part consists of individual measuring experiments utilizing the sensors and their comparison with medical tools.

Page generated in 0.0713 seconds