Background： Accelerometers have been suggested to provide additional information during the 6-min walk test which may be useful in evaluating changes in functional exercise capacity. The aim of the study was to ident...Background： Accelerometers have been suggested to provide additional information during the 6-min walk test which may be useful in evaluating changes in functional exercise capacity. The aim of the study was to identify whether the additional information measured by the My Wellness Key^TM（MWK） accelerometer during a treadmill 6-min walk test（t-6MWT） was related to currently used outcome measures.Methods： Fifteen participants（9 males, 6 females） performed a self-paced t-6MWT. Respiratory gas analysis and walking distance were measured whilst wearing the MWK.Results： A significant correlation was established between activity counts and 6-min walk distance（6MWD）（r=-0.847, p 〈 0.001） yet not 6-min walk work（6MWW）（r=-0.337, p=0.220）. Energy expenditure estimated by the MWK was strongly correlated to 6MWW（r=0.938, p 〈 0.001）but not 6MWD（r=0.477, p=0.072）. The MWK significantly underestimated energy expenditure（36.73, CI=33.9-39.7 kcal） compared to gas analysis（54.35, CI=46.2-61.4 kcal） demonstrating poor agreement between the two analyses（Bias=-17.61 kcal, Limits of agreement=-37.4,t2.2 kcal）. Measurement of time spent undertaking light, moderate, and vigorous physical activity was not significantly different（ p 〉 0.05）between the MWK and gas analysis.Conclusion： Estimated energy expenditure provided by the MWK was strongly correlated to 6MWW; however, MWK underestimated energy expenditure as measured by gas analysis. The MWK may provide outcome data that supplement those currently provided by the 6MWD for functional capacity assessment during the t-6MWT.展开更多
The TFR（Tampered Failure Rate） model was proposed by Bhattacharyya and Soejoeti（1989） for step-stress accelerated life tests, On step-stress completely accelerated test occasions, the paper gives a method of estim...The TFR（Tampered Failure Rate） model was proposed by Bhattacharyya and Soejoeti（1989） for step-stress accelerated life tests, On step-stress completely accelerated test occasions, the paper gives a method of estimating parameters under a normal stress.展开更多
The precise hydraulic valve is widely used in various industrial fields like aircraft, automobile and general machinery. Linear actuator is the most important device for driving the precise hydraulic valve. The reliab...The precise hydraulic valve is widely used in various industrial fields like aircraft, automobile and general machinery. Linear actuator is the most important device for driving the precise hydraulic valve. The reliable operation of linear actuator has effects on the overall hydraulic system. The performance of linear actuator relies on frequency response and step response according to arbitrary input signal. In this paper, the analysis for the components of linear actuator is performed to satisfy the reliable operation and response characteristics through the reliability analysis, and also deducted the design equations to realize the reliable operation and fast response characteristics of voice coil type linear actuator for servo valve operation through the empirical knowledge of experts and electromagnetic theories. The design equations are suggested to determine the values of design parameters of linear actuator as like bobbin size, length of yoke and plunger and turn number of coil, and calculated the life test time of linear actuator for verification of reliability of the prototype. In addition, for reducing the life test time, the acceleration model of linear actuator is proposed and the acceleration factor is calculated considering the field operating conditions. And then, the achieved design values are verified through accelerated life test and performance tests using some prototypes of linear actuators adapted in servo valve.展开更多
文摘Background： Accelerometers have been suggested to provide additional information during the 6-min walk test which may be useful in evaluating changes in functional exercise capacity. The aim of the study was to identify whether the additional information measured by the My Wellness Key^TM（MWK） accelerometer during a treadmill 6-min walk test（t-6MWT） was related to currently used outcome measures.Methods： Fifteen participants（9 males, 6 females） performed a self-paced t-6MWT. Respiratory gas analysis and walking distance were measured whilst wearing the MWK.Results： A significant correlation was established between activity counts and 6-min walk distance（6MWD）（r=-0.847, p 〈 0.001） yet not 6-min walk work（6MWW）（r=-0.337, p=0.220）. Energy expenditure estimated by the MWK was strongly correlated to 6MWW（r=0.938, p 〈 0.001）but not 6MWD（r=0.477, p=0.072）. The MWK significantly underestimated energy expenditure（36.73, CI=33.9-39.7 kcal） compared to gas analysis（54.35, CI=46.2-61.4 kcal） demonstrating poor agreement between the two analyses（Bias=-17.61 kcal, Limits of agreement=-37.4,t2.2 kcal）. Measurement of time spent undertaking light, moderate, and vigorous physical activity was not significantly different（ p 〉 0.05）between the MWK and gas analysis.Conclusion： Estimated energy expenditure provided by the MWK was strongly correlated to 6MWW; however, MWK underestimated energy expenditure as measured by gas analysis. The MWK may provide outcome data that supplement those currently provided by the 6MWD for functional capacity assessment during the t-6MWT.
文摘The TFR（Tampered Failure Rate） model was proposed by Bhattacharyya and Soejoeti（1989） for step-stress accelerated life tests, On step-stress completely accelerated test occasions, the paper gives a method of estimating parameters under a normal stress.
文摘The precise hydraulic valve is widely used in various industrial fields like aircraft, automobile and general machinery. Linear actuator is the most important device for driving the precise hydraulic valve. The reliable operation of linear actuator has effects on the overall hydraulic system. The performance of linear actuator relies on frequency response and step response according to arbitrary input signal. In this paper, the analysis for the components of linear actuator is performed to satisfy the reliable operation and response characteristics through the reliability analysis, and also deducted the design equations to realize the reliable operation and fast response characteristics of voice coil type linear actuator for servo valve operation through the empirical knowledge of experts and electromagnetic theories. The design equations are suggested to determine the values of design parameters of linear actuator as like bobbin size, length of yoke and plunger and turn number of coil, and calculated the life test time of linear actuator for verification of reliability of the prototype. In addition, for reducing the life test time, the acceleration model of linear actuator is proposed and the acceleration factor is calculated considering the field operating conditions. And then, the achieved design values are verified through accelerated life test and performance tests using some prototypes of linear actuators adapted in servo valve.
