With the development of vehicle gearbox to high-power-density and high-speed, how to predict and optimize the dynamic characteristics of vehicle gearbox becomes increasingly prominent. Aiming at the vehicle gearbox, t...With the development of vehicle gearbox to high-power-density and high-speed, how to predict and optimize the dynamic characteristics of vehicle gearbox becomes increasingly prominent. Aiming at the vehicle gearbox, this paper comprehensively and deeply studies the dynamic characteristics under the multi-boundary conditions. The generation mechanism of the multi-source excitations triggering the gearbox vibration is analyzed firstly. The vibration transfer path of the gearbox is explored. Secondly, the engine excitation, the gear meshing excitation and the bearing support load are numerically calculated. According to the finite element method,a fluid-solid coupling finite element model of the gearbox body is established to predict the gearbox dynamic responses based on the Galerkin method and the Hamiltonian variational principle. Finally, the effects of the excitation condition, oil height and reinforcement forms on the vibration responses of the gearbox body are thoroughly studied by simulation. The analysis indicates that it not only helps to modify and improve the method of forecasting the gearbox dynamic response, and also provides the theoretical and technical guidance for the gearbox design and optimization.展开更多
This paper explores the dynamic nature of the transformation of public housing regimes in urban China since the abolishment of the urban welfare housing system in the late 1990s. We summarize the latest progress in th...This paper explores the dynamic nature of the transformation of public housing regimes in urban China since the abolishment of the urban welfare housing system in the late 1990s. We summarize the latest progress in the development of public housing in post- reform China and investigate the driving forces behind these developments. A close examination of the public rental housing program in Shanghai helps to show that the recent revival of public housing in Chinese cities is mostly driven by the desire for economic growth. We conclude that the state provision of housing could be a short-run state remedy to alleviate economic imbalance and social inequality. However, in the long run China needs to seek more effective solutions to solve the low-income population＇s housing affordability problems.展开更多
基金the National Natural Science Foundation of China(Nos.51505402 and 51405410)the Education and Scientific Research Projects of Young and Middle-Aged Teachers in Fujian Province in 2014(No.JA14245)
文摘With the development of vehicle gearbox to high-power-density and high-speed, how to predict and optimize the dynamic characteristics of vehicle gearbox becomes increasingly prominent. Aiming at the vehicle gearbox, this paper comprehensively and deeply studies the dynamic characteristics under the multi-boundary conditions. The generation mechanism of the multi-source excitations triggering the gearbox vibration is analyzed firstly. The vibration transfer path of the gearbox is explored. Secondly, the engine excitation, the gear meshing excitation and the bearing support load are numerically calculated. According to the finite element method,a fluid-solid coupling finite element model of the gearbox body is established to predict the gearbox dynamic responses based on the Galerkin method and the Hamiltonian variational principle. Finally, the effects of the excitation condition, oil height and reinforcement forms on the vibration responses of the gearbox body are thoroughly studied by simulation. The analysis indicates that it not only helps to modify and improve the method of forecasting the gearbox dynamic response, and also provides the theoretical and technical guidance for the gearbox design and optimization.
基金The research is supported by funding from the National Science Foundation of China （Grant Nos. NSF7161101095 NSF71573166 NSF71173045） and the Key Social Science Project of Ministry of Education of China （13JZD009）.
文摘This paper explores the dynamic nature of the transformation of public housing regimes in urban China since the abolishment of the urban welfare housing system in the late 1990s. We summarize the latest progress in the development of public housing in post- reform China and investigate the driving forces behind these developments. A close examination of the public rental housing program in Shanghai helps to show that the recent revival of public housing in Chinese cities is mostly driven by the desire for economic growth. We conclude that the state provision of housing could be a short-run state remedy to alleviate economic imbalance and social inequality. However, in the long run China needs to seek more effective solutions to solve the low-income population＇s housing affordability problems.
