In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different composition...In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different compositions Ag-10CdO, Ag-7.6SnO2-2.3ln2O3 and Ag-10ZnO were prepared by internal oxidation process under identical processing conditions. These materials were tested for electrical conductivity, hardness, and erosion loss. Performing an accelerated test on the actual contactor assessed the electrical performance, involving erosion loss and temperature rise of the processed materials. The arc-eroded surface was characterized under scanning electron microscope. The study of the eroded surfaces of contacts indicates that the thermal stability of metal oxides depends on nature of silver-metal oxide interface and their mode of erosion. An attempt is made to correlate the surface features of the eroded contacts with the thermal stability of metal oxides.展开更多
The radial force is a critical factor to determine the sealing performance of radial lip seals.The effects of radial force produced by garter spring and interference on the static contact properties and sealing perfor...The radial force is a critical factor to determine the sealing performance of radial lip seals.The effects of radial force produced by garter spring and interference on the static contact properties and sealing performance of a radial lip seal are investigated by numerical simulations and experiments.Finite-element analysis and mixed elastohydrodynamic lubrication simulation are used.Radial force,contact width,temperature in the sealing zone,the reverse pumping rate and friction torque are measured.A critical value of interference for a cost-effectively designed radial lip seal is found.Spring force is required to compensate the decrease of the radial force because of the interference and used as a possible way to obtain intelligent control of sealing performance.The quantitative results gotten in this study could provide guide for the seal design and improvement.展开更多
基于重庆市2008年第17周~2011年第52周手足口病分年龄组的数据,分析了重庆市手足口病的季节性模式及各年龄所占比例,应用催化模型、时间序列易感者-感染者-康复者（time series susceptible infected recovered,TSIR）模型分别估计了重...基于重庆市2008年第17周~2011年第52周手足口病分年龄组的数据,分析了重庆市手足口病的季节性模式及各年龄所占比例,应用催化模型、时间序列易感者-感染者-康复者（time series susceptible infected recovered,TSIR）模型分别估计了重庆市手足口病不同年龄的感染力及随时间变化的人群接触率,研究了重庆市手足口病感染的高风险年龄以及手足口病接触率的季节性.结果表明,重庆市手足口病的发病呈现春季和冬季的两个高峰：5~6月大高峰,11~12月小高峰;患者主要集中在5岁以下儿童,2岁儿童患病的最多;不同年龄组手足口病的感染力不同：3~4岁年龄组感染力最高,因此3~4岁儿童被手足口病传染的风险最大;在成人中感染力在35~39岁较高;人群接触率呈现季节性：寒暑假期间接触率增加.展开更多
The wear rate between the rotors of a hypotrochoidal gear pump is characterized.Using the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated...The wear rate between the rotors of a hypotrochoidal gear pump is characterized.Using the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated through the calculation of the Hertzian contact stress.Based on the above results and the sliding velocity between the rotors,a genetic algorithm (GA) was used as an optimization technique forminimizing the wear rate proportional factor (WRPF).The result shows that the wear rate or the WRPF can be reduced considerably,e.g.approximately 12.8%,throughout the optimization using GA.展开更多
文摘In the present work investigations have been made to see the role of metal oxides on the performance of the silver metal oxides electrical contact materials. Silver metal oxide materials of three different compositions Ag-10CdO, Ag-7.6SnO2-2.3ln2O3 and Ag-10ZnO were prepared by internal oxidation process under identical processing conditions. These materials were tested for electrical conductivity, hardness, and erosion loss. Performing an accelerated test on the actual contactor assessed the electrical performance, involving erosion loss and temperature rise of the processed materials. The arc-eroded surface was characterized under scanning electron microscope. The study of the eroded surfaces of contacts indicates that the thermal stability of metal oxides depends on nature of silver-metal oxide interface and their mode of erosion. An attempt is made to correlate the surface features of the eroded contacts with the thermal stability of metal oxides.
基金supported by the National Natural Science Foundation of China(Grant No.51175283)the National Science and Technology Major Project of China(Grant No.2013ZX04010021)the Ph.D Programs Foundation of Ministry of Education of China(Grant No.20130002110006)
文摘The radial force is a critical factor to determine the sealing performance of radial lip seals.The effects of radial force produced by garter spring and interference on the static contact properties and sealing performance of a radial lip seal are investigated by numerical simulations and experiments.Finite-element analysis and mixed elastohydrodynamic lubrication simulation are used.Radial force,contact width,temperature in the sealing zone,the reverse pumping rate and friction torque are measured.A critical value of interference for a cost-effectively designed radial lip seal is found.Spring force is required to compensate the decrease of the radial force because of the interference and used as a possible way to obtain intelligent control of sealing performance.The quantitative results gotten in this study could provide guide for the seal design and improvement.
文摘基于重庆市2008年第17周~2011年第52周手足口病分年龄组的数据,分析了重庆市手足口病的季节性模式及各年龄所占比例,应用催化模型、时间序列易感者-感染者-康复者（time series susceptible infected recovered,TSIR）模型分别估计了重庆市手足口病不同年龄的感染力及随时间变化的人群接触率,研究了重庆市手足口病感染的高风险年龄以及手足口病接触率的季节性.结果表明,重庆市手足口病的发病呈现春季和冬季的两个高峰：5~6月大高峰,11~12月小高峰;患者主要集中在5岁以下儿童,2岁儿童患病的最多;不同年龄组手足口病的感染力不同：3~4岁年龄组感染力最高,因此3~4岁儿童被手足口病传染的风险最大;在成人中感染力在35~39岁较高;人群接触率呈现季节性：寒暑假期间接触率增加.
基金supported by Changwon National University in 2010,Korea
文摘The wear rate between the rotors of a hypotrochoidal gear pump is characterized.Using the knowledge of shape design on the rotors,the contact stresses without hydrodynamic effect between the rotor teeth were evaluated through the calculation of the Hertzian contact stress.Based on the above results and the sliding velocity between the rotors,a genetic algorithm (GA) was used as an optimization technique forminimizing the wear rate proportional factor (WRPF).The result shows that the wear rate or the WRPF can be reduced considerably,e.g.approximately 12.8%,throughout the optimization using GA.
