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Factors associated with lower gait speed among the elderly living in a developing country: a cross-sectional population-based study

Busch, Telma de Almeida; Duarte, Yeda Aparecida; Nunes, Daniella Pires; Lebrao, Maria Lucia; Naslavsky, Michel Satya; Rodrigues, Anelise dos Santos; Amaro Jr, Edson
Fonte: BMC Publicador: BMC
Tipo: Artigo de Revista Científica
EN
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Abstract Background Among community-dwelling older adults, mean values for gait speed vary substantially depending not only on the population studied, but also on the methodology used. Despite the large number of studies published in developed countries, there are few population-based studies in developing countries with socioeconomic inequality and different health conditions, and this is the first study with a representative sample of population. To explore this, the association of lower gait speed with sociodemographic, anthropometric factors, mental status and physical health was incorporated participants’ weight (main weight) in the analysis of population of community-dwelling older adults living in a developing country. Methods This was a cross-sectional population based on a sample of 1112 older adults aged 60 years and over from Health, Wellbeing and Aging Study cohort 2010. Usual gait speed (s) to walk 3 meters was stratified by sex and height into quartiles. Multiple regression analysis was performed to investigate the independent effect of each factor associated with a slower usual gait speed. Results The average walking speed of the elderly was 0.81 m/s – 0.78 m/s among women and 0.86 m/s among men. In the final model...

"Estudo comparativo de aços rápidos AISI M3:2 produzidos por diferentes processos de fabricação" ; COMPARATIVE STUDY OF AISI M3:2 HIGH SPEED STEEL PRODUCED THROUGH DIFFERENT TECHNIQUES OF MANUFACTURING

Araujo Filho, Oscar Olimpio de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/06/2006 PT
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Neste trabalho aços rápidos ao molibdênio AISI M3:2 obtidos por diferentes processos de fabricação, submetidos ao mesmo procedimento de tratamento térmico, foram avaliados no que concerne às propriedades mecânicas de resistência à ruptura transversal e dureza. Os materiais em questão constaram dos aços rápidos comerciais Sinter 23 obtido por metalurgia do pó, o aço rápido VWM3C obtido pelo processo convencional e o aço rápido M3:2 obtido por uma técnica de metalurgia do pó que consiste de compactação uniaxial a frio de pós atomizados a água com e sem a adição de uma pequena quantidade de carbono na forma de grafite (0,3% em massa) e sinterização a vácuo com fase líquida. Esses aços rápidos foram avaliados através da comparação de suas propriedades. O aço rápido M3:2 foi sinterizado a vácuo podendo vir a se constituir numa alternativa economicamente mais viável do que o aço rápido MP Sinter 23 obtido por uma técnica de sinterização por compactação isostática a quente e com propriedades similares ao aço rápido processado pela rota convencional. A caracterização do aço rápido sinterizado a vácuo consistiu de medidas de densidades do compactado e após a sinterização. A sinterização produziu uma microestrutura aceitável e densidades próximas da densidade teórica desse aço rápido. A resistência à ruptura transversal foi avaliada através de ensaios de flexão em três pontos e a dureza através de medidas de dureza Rockwell C e Vickers. Os aços rápidos foram avaliados no que tange à microestrutura por uma técnica de microscopia eletrônica de varredura (MEV). Estabeleceu-se assim uma relação entre a microestrutura e a resistência à ruptura transversal desses aços após o tratamento térmico. Uma técnica de difração de raios X foi utilizada para a determinação das fases presentes e detecção da austenita retida. A contribuíção desse trabalho consiste na avaliação da relação microestrutura / propriedades mecânicas desses aços rápidos bem como na viabilização do aço rápido sinterizado a vácuo.; In this work AISI M3:2 high speed steels obtained through different techniques of manufacturing...

Contribuição ao estudo de aerogeradores de velocidade e passo variáveis com gerador duplamente alimentado e sistema de controle difuso; Contribution to the study of fuzzy control applied to variable-speed variable-pitch wind generators with double-fed induction generator

Amêndola, Cesar Augusto Moreira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 05/10/2007 PT
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A captação eficaz da energia eólica ocorre por meio de turbinas de três pás com ângulo de passo e velocidade de rotação ajustáveis, sendo o ajuste do ângulo de passo utilizado para limitar a captação de energia na ocorrência de ventos muito fortes e o ajuste da velocidade de rotação utilizado para maximizar a captação da energia cinética dos ventos fracos. Neste regime de operação, o gerador deve converter a energia mecânica de entrada, caracterizada por velocidade de rotação e conjugado variáveis, em energia elétrica de saída nos padrões da rede elétrica a que estão conectados, caracterizada por tensão de valor eficaz e freqüência constantes. No presente trabalho, a conversão eletromecânica de energia é realizada por um gerador de indução duplamente alimentado, excitado pelos enrolamentos rotóricos por meio de um conversor eletrônico. O comportamento estocástico dos ventos e as não linearidades significativas da turbina eólica e do gerador motivaram a utilização de controladores difusos, elaborados de acordo com a seguinte metodologia: a base de regras foi estabelecida a partir dos princípios físicos e da dinâmica desejada para o sistema em malha fechada; as funções de pertinência de entrada foram distribuídas de maneira a garantir uma maior sensibilidade nas regiões próximas ao valor de referência; a distribuição das funções de pertinência de saída proporciona um aumento significativo da intensidade da ação de controle conforme a saída do sistema se afaste do valor de referência; e...

Capacidade e relação fluxo-velocidade em autoestradas e rodovias de pista dupla paulistas; Capacity and speed-flow relationship for freeways and multilane highways in the state of São Paulo

Andrade, Gustavo Riente de
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 07/05/2012 PT
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Neste trabalho, calibra-se um modelo que descreva a relação fluxo-velocidade em autoestradas e rodovias de pista dupla, considerando as recomendações tecidas pelos autores envolvidos na elaboração do modelo do Highway Capacity Manual - HCM 2010. Para tanto, foi utilizada uma amostra de 788.122 observações, coletadas por 25 estações em quatro rodovias paulistas: SP-348, SP-021, SP-280 e SP 270. A análise dos dados mostrou que, conforme preconizado pelo HCM 2010, existe um intervalo de fluxos no qual a velocidade se mantém constante, o que corresponde à velocidade de fluxo livre. Em seguida, verificou-se que a classificação do HCM 2010, entre autoestradas e rodovias de pista dupla, não se mostra adequada para a amostra estudada, tendo sido indicada a divisão entre rodovias urbanas e rurais. Para esses grupos, foram propostos valores representativos para a capacidade e calibrada a relação fluxo-velocidade. A comparação entre os dois conjuntos de curvas produzidos mostrou que a velocidade média da corrente de tráfego nas rodovias urbanas apresenta uma queda mais precoce e acentuada do que a observada em rodovias rurais. Além disso...

Relação entre a força propulsora e a velocidade nos quatro estilos competitivos da natação; Relationship between the propulsive force and speed in the four competitive strokes in swimming

Santos Junior, Joel Moraes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 29/01/2013 PT
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Embora muitos estudos tenham investigado a contribuição da força propulsora na velocidade de nadadores, a maioria das pesquisas se restringiu ao estilo crawl e no nado como um todo. Sendo assim, o objetivo do presente estudo foi mensurar e comparar a força propulsora e o desempenho de velocidade nos quatro estilos competitivos e verificar a relação entre elas durante o nado completo, o nado somente de pernas e o nado somente de braços em nadadores competitivos. Participaram do estudo 37 nadadores do sexo masculino com experiência competitiva de no mínimo dois anos, com idade entre 15 e 19 anos. A amostra foi dividida pelos estilos borboleta (n=9), costas (n=7), peito (n=9) e crawl (n=12). Foram medida as variáveis de força propulsora (VFP) no nado atado (NA) nas seguintes situações; força propulsora máxima de nado em 10 segundos (FPM10), força propulsora máxima de pernas em 10 segundos (FPMp), força propulsora máxima de braços em 10 segundos (FPMb), força propulsora máxima de nado em 25 segundos (FPM25) força propulsora média de nado em 25 segundos (FPm25). Também foi mensurada a velocidade nas metragens de 15 e 50 metros (V15 e V50). Cada nadador realizou os testes de força e velocidade nos principais estilos de competição. Os resultados demonstraram correlações entre as VFP com a velocidade para os quatro estilos competitivos no nado completo (entre r=0...

Coeficiente de atrito no ensaio do anel: estudo do efeito da velocidade de deformação, grau de deformação e aderência de material à superfície da ferramenta.; Friction coefficient at compression ring test: study of effect of conformation speed, height reduction and the adhesion of material at tool surface.

Soares, Enio Yamamotu Ferreira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 28/03/2013 PT
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O ensaio do anel consiste na compressão de uma amostra em formato de anel com as proporções 6:3:2 (diâmetro externo; diâmetro interno; altura) que foi deformada em sua altura. Neste trabalho realizaram-se ensaios de compressão de anel para três ordens de grandeza de velocidades de deformação: 3,00; 0,30; 0,03 mm/s, e dois graus de redução na altura: 20% e 50%. Os ensaios foram realizados em duas condições, uma na qual os ensaios sucessivos foram realizados na mesma posição da ferramenta sem polimento da mesma e outra na qual entre ensaios consecutivos, as ferramentas foram polidas recuperando sua condição superficial inicial. Para cada condição ensaiada sobre superfície polida foram realizadas 10 réplicas. Para ensaios sobre superfície sem polimento intermediário foram realizadas 10 compressões de anéis consecutivas. As ferramentas foram fabricadas de aço ferramenta e os corpos de prova, anéis, em aço SAE 1020 nas dimensões 18 x 9 x 6 mm (raio externo, raio interno e altura). Nas observações das superfícies de trabalho bem como das microestruturas foi utilizado microscópio óptico e microscópio eletrônico de varredura. Para os ensaios com polimento das ferramentas entre ensaios observou-se que: a) A elevação da redução de altura não resultou na variação do coeficiente de atrito para as três velocidades estudadas. b) Para 50% de deformação a elevação da velocidade resultou numa pequena...

Blood lactate response and critical speed in swimmers aged 10-12 years of different standards

Denadai, B. S.; Greco, C. C.; Teixeira, M.
Fonte: E & Fn Spon Publicador: E & Fn Spon
Tipo: Artigo de Revista Científica Formato: 779-784
ENG
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It has previously been shown that measurement of the critical speed is a non-invasive method of estimating the blood lactate response during exercise. However, its validity in children has yet to be demonstrated. The aims of this study were: (1) to verify if the critical speed determined in accordance with the protocol of Wakayoshi et al. is a non-invasive means of estimating the swimming speed equivalent to a blood lactate concentration of 4 mmol . l(-1) in children aged 10-12 years; and (2) to establish whether standard of performance has an effect on its determination. Sixteen swimmers were divided into two groups: beginners and trained. They initially completed a protocol for determination of speed equivalent to a blood lactate concentration of 4 mmol . l(-1). Later, during training sessions, maximum efforts were swum over distances of 50, 100 and 200 m for the calculation of the critical speed. The speeds equivalent to a blood lactate concentration of 4 mmol . l(-1) (beginners = 0.82 +/- 0.09 m . s(-1), trained = 1.19 +/- 0.11 m . s(-1); mean +/- s) were significantly faster than the critical speeds (beginners = 0.78 +/- 0.25 m . s(-1), trained = 1.08 +/- 0.04 m . s(-1)) in both groups. There was a high correlation between speed at a blood lactate concentration of 4 mmol . l(-1) and the critical speed for the beginners (r = 0.96...

Driver’s perceptions about the effects of speed regulation systems in the driving task

Ferreira, Ana Luísa Barradas Vicente
Fonte: Repositório Comum de Portugal Publicador: Repositório Comum de Portugal
Tipo: Dissertação de Mestrado
Publicado em //2012 ENG
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Speed regulation systems like the cruise control (CC) and the speed limiter (SL) are becoming a standard feature in vehicles nowadays. However, these systems add a certain level of automation to the driving task and so they have the potential to change the way people drive. In order to understand the potential that these systems have in terms of road safety, it is crucial to understand how drivers percept the effects of the systems during the driving task. Then, the aim of the present research was to identify driver’s perceptions about the effects of speed regulation systems, more specifically the cruise control and the speed limiter, in the driving task and, to accomplish this goal, a questionnaire was applied. The main findings were that females are more prone to keep speeds equal to the road speed limit, and that when using both, cruise control and speed limiter, drivers are more available to comply with road speed limits. It was also found that the CC has a bigger impact than the SL when it comes to engaging into secondary tasks while driving.

Usual gait speed assessment in middle-aged and elderly Brazilian subjects

Novaes,Rômulo D.; Miranda,Aline S.; Dourado,Victor Z.
Fonte: Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia Publicador: Associação Brasileira de Pesquisa e Pós-Graduação em Fisioterapia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2011 EN
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OBJECTIVES: To evaluate the usual gait speed of asymptomatic adult and elderly Brazilians with a 10-meter walk test and to compare the results with foreign reference values. METHODS: Seventy-nine asymptomatic volunteers >40 years old of both genders were assessed. After anamnesis, anthropometry and the application of a habitual physical activity questionnaire, the volunteers were submitted to a 10-meter walk test at usual speed by means of which gait speed, the number of steps and length of stride were calculated. RESULTS: Except for age, all study variables were significantly lower in women. Subjects >70 years old presented a significantly lower gait speed than subjects between 40 and 49 years old and between 50 and 59 in both men (1.09±0.18 m/s, 1.35±0.11 m/s and 1.34±0.22 m/s, respectively) and women (1.02±0,10 m/s, 1.27±0.20 m/s and 1.27±0,15 m/s), respectively). Gait speed showed moderate correlations with age (r=-0.41, p<0.001) and height (r=0.35, p=0.001). After multiple regression analysis, age and gender were selected as relevant attributes of gait speed in that they explained 24.6% of this variable. The gait speed values in this study were significantly lower than foreign reference values (p<0.05). CONCLUSIONS: The gait speed presented age-related decline and values significantly lower than those described for foreign populations. This finding indicates the need for comprehensive investigation of gait speed reference values for the Brazilian population.

Association between Blood Lead and Walking Speed in the National Health and Nutrition Examination Survey (NHANES 1999–2002)

Ji, John S.; Elbaz, Alexis; Weisskopf, Marc G.
Fonte: National Institute of Environmental Health Sciences Publicador: National Institute of Environmental Health Sciences
Tipo: Artigo de Revista Científica
EN_US
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Background: Walking speed is a simple and reliable measure of motor function that is negatively associated with adverse health events in older people, including falls, disability, hospital admissions, and mortality. Lead has adverse affects on human health, particularly on the vascular and neurological systems. Objective: We explored the hypothesis that lead is associated with slower walking speed. Methods: We used U.S. National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999–2002. The time to walk 20 ft (walking speed) was measured among 1,795 men and 1,798 women ≥ 50 years of age. The association between walking speed and quintiles of blood lead concentration was estimated separately in men and women using linear regression models adjusted for age, education, ethnicity, alcohol use, smoking status, height, and waist circumference. Results: Mean blood lead concentrations and walking speeds were 2.17 μg/dL and 3.31 ft/sec in women, and 3.18 μg/dL and 3.47 ft/sec in men, respectively. Among women, walking speed decreased with increasing quintiles of blood lead, resulting in an estimated mean value that was 0.11 ft/sec slower (95% CI: –0.19, –0.04; p-trend = 0.005) for women with blood lead concentrations in the highest versus lowest quintile. In contrast...

Regional Impacts of High Speed Rail in China : Baseline Report for a Case Study of Yunfu in Guangdong Province

Jin, Ying; Bullock, Richard; Fang, Wanli
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
EN_US
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This paper contains an initial reconnaissance of the situation in Yunfu, prior to the NanGuang project construction. It provides a brief overview of the trajectory of economic development in Yunfu from an economy that was dominated by primary industries to that by secondary industries. The development of local transport infrastructure is reviewed, as is the more detailed structure of local industries, with special emphasis on dominant industrial sectors and the planned industrial parks. The experience of high speed rail development impact elsewhere was drawn upon to reflect on the possible regional economic outcomes that might emerge following the opening of the Nanning-Guangzhou high speed rail. The structure of and the approach to a before and after monitoring study is considered. The remainder of the paper is divided into six parts. Part two gives a brief overview of the economic development in Yunfu municipality since its establishment in 1994. Part three describes local transport links and infrastructure. Part four provides a description of the internal structure of local industries...

Inspection time and general speed of processing

Gregory, T.; Burns, N.
Fonte: Pergamon-Elsevier Science Ltd Publicador: Pergamon-Elsevier Science Ltd
Tipo: Artigo de Revista Científica
Publicado em //2003 EN
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Recent research suggests that the relationship between inspection time (IT) and psychometric intelligence arises because IT is a measure of general speed of processing (Gs). However, hierarchical models of intelligence propose several distinct speed of processing factors; this study examines IT in relation to these multiple speed factors. Participants (N=102) completed tests of speed of processing yielding 18 measures. Factor analysis revealed a second order general speed factor (Gs) and four group factors: perceptual speed, visualisation speed, decision time and movement time. IT correlated with a visualisation speed factor (r=0.36) and with a perceptual speed factor (r=0.28). However, the correlation between IT and perceptual speed was near-zero when the correlation with visualisation speed was partialled out. These findings are consistent with the notion that IT is a measure of Gs but suggest that IT most directly measures speed of visualisation processes. These results are also congruent with research on the psychophysics of IT.; http://www.elsevier.com/wps/find/journaldescription.cws_home/603/description#description; Tess A. O’Connor and Nicholas R. Burns

Impacts of Lower Speed Limits in South Australia

Woolley, J.; Dyson, C.; Taylor, M.; Zito, R.; Stazic, B.
Fonte: International Association of Traffic and Safety Sciences Publicador: International Association of Traffic and Safety Sciences
Tipo: Artigo de Revista Científica
Publicado em //2002 EN
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Australia has recently undergone a change of urban speed limits in most of its jurisdictions. The political and social shift in attitudes required for this change is significant in a country that has a strong reliance on the use of the private motor vehicle. At present five states and one territory have lowered the speed limit in urban areas from 60km/h to 50km/h. Of the remaining two states and territories, one has already implemented lower speed limits (40km/h) in small areas within cities. In the majority of cases, the only criterion for judging the success of such schemes is an observed reduction in both speeds and crash numbers.  This paper reports on a more holistic assessment of such schemes taking into account factors in addition to speed and crashes including: traffic volume displacement, physical road network characteristics, environmental factors, community ownership and acceptance, enforcement effort and impact on travel times. The research work has included the analysis of extensive traffic data, community surveys and focus groups, the collection of environmental and travel time data from an instrumented probe vehicle and the computer modelling of road networks. The work reported is based on over 10 years of working with a 40km/h lower urban speed limit area in South Australia. The paper expands the notion of using speed and crash outcomes as the only criteria for measuring the success of lower speed limit schemes.; J. E. Wooley...

Rural speed and crash risk

Kloeden, C.; McLean, A.
Fonte: Road Safety Research Publicador: Road Safety Research
Tipo: Conference paper
Publicado em //2001 EN
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36.43%
The relationship between free travelling speed and the risk of involvement in a casualty crash in 80 km/h or greater speed limit zones in rural South Australia was quantified using a case control study design. The crashes involving the 83 case passenger vehicles were investigated at the scene by the Road Accident Research Unit and reconstructed using the latest computer aided crash reconstruction techniques. The 830 control passenger vehicles were matched to the cases by location, direction of travel, time of day, and day of week and their speeds were measured with a laser speed gun. It was found that the risk of involvement in a casualty crash increased more than exponentially with increasing free travelling speed above the mean traffic speed and that travelling speeds below the mean traffic speed were associated with a lower risk of being involved in a casualty crash. The effect of hypothetical speed reductions on all of the 167 crashes investigated indicated large potential safety benefits from even small reductions in rural travelling speeds.; C.N. Kloeden and A.J. McLean

Travelling speed and the risk of crash involvement

Kloeden, C.; McLean, J.; Moore, V.; Ponte, G.
Fonte: Federal Office of Road Safety, Transport and Communiations Publicador: Federal Office of Road Safety, Transport and Communiations
Tipo: Relatório
Publicado em //1997 EN
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The relationship between free travelling speed and the risk of involvement in a casualty crash in a 60 km/h speed limit zone was quantified using a case control study design. The 151 case vehicles were passenger cars involved in crashes in the Adelaide metropolitan area which were investigated at the scene by the NHMRC Road Accident Research Unit and reconstructed using the latest computer aided crash reconstruction techniques. The 604 control vehicles were passenger cars matched to the cases by location, direction of travel, time of day, and day of week and their speeds were measured with a laser speed gun. It was found that the risk of involvement in a casualty crash doubled with each 5 km/h increase in free travelling speed above 60 km/h. Hypothetical speed reductions applied to the case vehicles indicated large potential safety benefits from even small reductions in travelling speed, particularly on arterial roads.; Kloeden CN, McLean AJ, Moore VM and Ponte G

Predicting walking METs and energy expenditure from speed or accelerometry

Brooks, A.; Gunn, S.; Withers, R.; Gore, C.; Plummer, J.
Fonte: Lippincott Williams & Wilkins Publicador: Lippincott Williams & Wilkins
Tipo: Artigo de Revista Científica
Publicado em //2005 EN
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36.44%
PURPOSE: a) Compare the predictive potential of speed and CSA(hip) (Computer Science Applications accelerometer positioned on the hip) for level terrain walking METs (1 MET = VO2 of 3.5 mL.kg(-1).min(-1)) and energy expenditure (kcal.min(-1)); b) cross-validate previously published CSA(hip)- and speed-based MET and energy expenditure prediction equations; c) measure self-paced walking speed, exercise intensity (METs) and energy expenditure in the middle aged population. METHODS: Seventy-two 35- to 45-yr-old volunteers walked around a level, paved quadrangle at what they perceived to be a moderate pace. Oxygen consumption was measured using the criterion Douglas bag technique. Speed, CSA(hip), heart rate, and Borg rating of perceived exertion were also monitored. RESULTS: Speed explained 10% more variance of walking METs than CSA(hip). Speed and mass explained 8% more variance of walking energy expenditure (kcal.min) than CSA(hip) and mass. The best previously published regression equations predict our walking METs and energy expenditures within 95% prediction limits of +/- 0.7 METs and +/- 1.0 kcal.min(-1), respectively. Women paced themselves at a significantly higher mean speed (5.5 km.h(-1)) and intensity (4.1 METs) than their male counterparts (5.2 km.h(-1) and 3.8 METs). Both genders expended approximately 0.75 kcal.kg(-1) for every kilometer of level terrain walked. CONCLUSION: Speed-based MET and energy expenditure predictions during level terrain walking were more accurate than those utilizing CSA(hip).; http://www.ncbi.nlm.nih.gov/pubmed/16015141; Brooks...

Simulation of rural travel times to quantify the impact of lower speed limits

Dutschke, J.; Woolley, J.
Fonte: RTA New South Wales; USB Publicador: RTA New South Wales; USB
Tipo: Conference paper
Publicado em //2009 EN
Relevância na Pesquisa
36.5%
The number and severity of rural road crashes has been shown to decrease with reduced traveling speed. One method of reducing the traveling speed on rural roads is to reduce the speed limit of those roads. Despite the considerable road safety benefits resulting from reduced speed limits, public opposition to the change exists. One of the main concerns of the public is the increase in travel times associated with a reduction in speed limit. In South Australia the default rural speed is 100kph, however many undivided rural roads in the state are signposted at 110kph. This study quantifies this increase in travel time on an arbitrary rural road in South Australia if the signposted speed limit was replaced with the defult speed limit of 100kph. A Markov model of travel time on an undivided rural road is developed. The model includes factors such as vehicle speed distributions, passing lanes, traffic congestion, and speed advisory signs. Real data collected on South Australian rural roads that have had a similar reduction in speed limit are used to define the distribution of speeds of vehicles before and after the change in speed limit. The model shows that an increase in travel time is expected, however this increase is less than is first predicted by considering only the allowed speed limit.; http://www.rsconference.com/RoadSafety/detail/978; J. K. Dutschke...

Recursive ray acoustics for three-dimensional sound-speed profiles

Polnicky, F. Wynn
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado Formato: 101 p.
EN_US
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Approved for public release; distribution is unlimited; A comparison of a simple recursive ray acoustics algorithm versus a ray acoustics algorithms based on solving a system of first-order ordinary differential equations was conducted. the recursive ray acoustics (RRA) was found to be accurate and relatively fast. The RRA algorithm is capable of handling sound speed as a function of all three spatial coordinates, and this capability was demonstrated. Two separate methods of representing a sound-speed profile (SSP) based on data points were examined: Akima cubic spline and spatial Fourier series (SFS). The SFS representation encountered difficulties in accurately modeling SSPs. Various techniques were applied to improve the SFS sound-speed representation. While accurate sound-speed fits eventually achieved, difficulties remained in the SFS modeling of first and second-order derivatives of the sound-speed data. The RRA algorithm was tested using the SFS sound-speed representation and found to be significantly inaccurate. A demonstration was conducted of the ability of the SFS sound-speed representation to incorporate randomness in the SSP.; http://archive.org/details/recursiverayacou00poln; Lieutenant, Canadian Navy

Effect of Gait Speed on Gait Rhythmicity in Parkinson's Disease: Variability of Stride Time and Swing Time Respond Differently

Frenkel-Toledo, Silvi; Giladi, Nir; Peretz, Chava; Gruendlinger, Leor; Herman, Talia Nunes; Hausdorff, Jeffrey M.
Fonte: BioMed Central Publicador: BioMed Central
Tipo: Artigo de Revista Científica
EN_US
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36.44%
Background: The ability to maintain a steady gait rhythm is impaired in patients with Parkinson's disease (PD). This aspect of locomotor dyscontrol, which likely reflects impaired automaticity in PD, can be quantified by measuring the stride-to-stride variability of gait timing. Previous work has shown an increase in both the variability of the stride time and swing time in PD, but the origins of these changes are not fully understood. Patients with PD also generally walk with a reduced gait speed, a potential confounder of the observed changes in variability. The purpose of the present study was to examine the relationship between walking speed and gait variability. Methods: Stride time variability and swing time variability were measured in 36 patients with PD (Hoehn and Yahr stage 2–2.5) and 30 healthy controls who walked on a treadmill at four different speeds: 1) Comfortable walking speed (CWS), 2) 80% of CWS 3) 90% of CWS, and 4) 110% of CWS. In addition, we studied the effects of walking slowly on level ground, both with and without a walker. Results: Consistent with previous findings, increased variability of stride time and swing time was observed in the patients with PD in CWS, compared to controls. In both groups, there was a small but significant association between treadmill gait speed and stride time variability such that higher speeds were associated with lower (better) values of stride time variability (p = 0.0002). In contrast...

Analyzing the United States Department of Transportation’s implementation strategy for high speed rail: Three case studies

Robinson, Ryan
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
EN_US
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High-speed rail (HSR) has become a major contributor to the transportation sector with a strong push by the Obama Administration and the Department of Transportation to implement high-speed rail in the United States. High-speed rail is a costly transportation alternative that has the potential displace some car and airport travel while increase energy security and environmental sustainability. This thesis will examine the United States high-speed rail implementation strategy by comparing it to the implementation strategies of France, Japan, and Germany in a multiple case study under four main criteria of success: economic profitability, reliability, safety, and ridership. Analysis will conclude with lessons to be taken away from the case studies and applied to the United States strategy. It is important to understand that this project has not been established to create a comprehensive implementation plan for high-speed rail in the United States; rather, this project is intended to observe the depth and quality of the current United States implementation strategy and make additional recommendations by comparing it with France, Japan, and Germany.