Nonlinearity is an important characteristic in electrostatic suspension system (ESS). This paper concludes the nonlinear parts in ESS, which generally result from the relationships between rotor displacement and capac...Nonlinearity is an important characteristic in electrostatic suspension system (ESS). This paper concludes the nonlinear parts in ESS, which generally result from the relationships between rotor displacement and capacitance, rotor displacement and electrostatic force, and control voltage and electrostatic force. In terms of the nonlinearities, a new control method with modified internal model control (IMC) was proposed to analyze the ESS, deduce the transfer function of the modified IMC controller in ESS, and simulate this new application in ESS. Comparing with proportional integral derivative (PID) control, IMC has only a parameter, and has better performance. As a result, IMC solves nonlinearity error well in ESS with only one uncertain parameter, and performs well when the rotor has large displacement.展开更多
New open manufacturing environments have been proposed aiming at realizing more flexible distributed manufacturing paradigms,which can deal with not only dynamic changes in volume and variety of products,but also chan...New open manufacturing environments have been proposed aiming at realizing more flexible distributed manufacturing paradigms,which can deal with not only dynamic changes in volume and variety of products,but also changes of machining equipments,dispersals of processing locations,and also with unscheduled disruptions.This research is to develop an integrated process planning and scheduling system,which is suited to this open,dynamic,distributed manufacturing environment.Multi-agent system(MAS)approaches are used for integration of manufacturing processing planning and scheduling in an open distributed manufacturing environment,in which process planning can be adjusted dynamically and manufacturing resources can increase/decrease according to the requirements.One kind of multi-level dynamic negotiated approaches to process planning and scheduling is presented for the integration of manufacturing process planning and scheduling.展开更多
The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics(CFD)approach.The first applied model is a one-equation SGS model for large eddy ...The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics(CFD)approach.The first applied model is a one-equation SGS model for large eddy simulation(LES)and the second one is the SST-SAS hybrid RANS-LES.These models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface(h/B)distances at two Reynolds numbers namely,2960 and 4740 based on the jet exit velocity(U_e)and the hydraulic diameter(2B).The predictions are compared with the experimental data in the literature and also the results from RANS k-εmodel.Comparisons show that both models can produce relatively good results.However,one-equation model(OEM)produced more accurate results especially at impingement region at lower jet-to-surface distances.In terms of heat transfer,the OEM also predicted better at different jet-to-surface spacings.It is also observed that both models show similar performance at higher h/B ratios.展开更多
According to the China Statistical Yearbook divided eight consumption expenditure, I set food, clothing, housing and household equipment and services as residents basic living expenses, of China＇ s rural pension repl...According to the China Statistical Yearbook divided eight consumption expenditure, I set food, clothing, housing and household equipment and services as residents basic living expenses, of China＇ s rural pension replacement rate level of demand is calculated. The financial revenue scale autoregressive model predicted 2010-2020, the scale of fiscal revenue, with Pratt ＆ Whitney type total pension should be of basic pension and substitution rate level of demand for pension accounts for fiscal revenue proportion of the international experience of fiscal income of 5% were measured and evaluated. The current basic pension in the short term to improve the life of the rural elderly has an important role, but the long-term need to continue to increase, should optimize the structure of fiscal expenditure.展开更多
For human assistance device, the particular properties are usually focused on high precision, compliant interaction, large torque generation and compactness of the mechanical system. To realize the high performance of...For human assistance device, the particular properties are usually focused on high precision, compliant interaction, large torque generation and compactness of the mechanical system. To realize the high performance of lower extremity augmentation device, in this paper, we introduce a novel control methodology for compact elastic module. Based on the previous work, the elastic module consists of two parts, i.e., the proximal interaction module and the distal control module. To improve the compactness of the exoskeleton, we only employ the distal control module to achieve both purposes of precision force control and human intention recognition with physical human-machine interaction. In addition, a novel control methodology, so-called high precision data-driven force control with disturbance observer is adopted in this paper. To assess our proposed control methodology, we compare our novel force control with several other control methodologies on the lower extremity augmentation single leg exoskeleton system. The experiment shows a satisfying result and promising application feasibility of the proposed control methodology.展开更多
A two dimensional model of the transient natural convection in a freezer is studied numerically by finite volume approach.The temperatures of the freezer outside surfaces and the evaporator vary in specified manners,w...A two dimensional model of the transient natural convection in a freezer is studied numerically by finite volume approach.The temperatures of the freezer outside surfaces and the evaporator vary in specified manners,which were taken from an experimental work.The fluid in the freezer is of the Bousinnesq type and the flow is assumed laminar,The transient heat conduction in the insulating layers and the temperature and velocity fields of the fluid are solved conjugately.The radiation heat transfer between the freezer inner surfaces is taken into account by using the additional source term method.The distributions of the local Nusselt number along the upper and lower surfaces of the evaporator and their average values in the period of periodically unsteady operation are calculated.Comparisons are made between the results with and without consideration of inner surface radiative heat transfer.It is found that the radiative heat transfer between the inner surfaces has a profound effect on the evaporator heat transfer characteristics.展开更多
基金Weaponry Advanced FundItem of China(No51409030101JW03)
文摘Nonlinearity is an important characteristic in electrostatic suspension system (ESS). This paper concludes the nonlinear parts in ESS, which generally result from the relationships between rotor displacement and capacitance, rotor displacement and electrostatic force, and control voltage and electrostatic force. In terms of the nonlinearities, a new control method with modified internal model control (IMC) was proposed to analyze the ESS, deduce the transfer function of the modified IMC controller in ESS, and simulate this new application in ESS. Comparing with proportional integral derivative (PID) control, IMC has only a parameter, and has better performance. As a result, IMC solves nonlinearity error well in ESS with only one uncertain parameter, and performs well when the rotor has large displacement.
基金International Cooperative Research Project of China(No.2006DFA73180)
文摘New open manufacturing environments have been proposed aiming at realizing more flexible distributed manufacturing paradigms,which can deal with not only dynamic changes in volume and variety of products,but also changes of machining equipments,dispersals of processing locations,and also with unscheduled disruptions.This research is to develop an integrated process planning and scheduling system,which is suited to this open,dynamic,distributed manufacturing environment.Multi-agent system(MAS)approaches are used for integration of manufacturing processing planning and scheduling in an open distributed manufacturing environment,in which process planning can be adjusted dynamically and manufacturing resources can increase/decrease according to the requirements.One kind of multi-level dynamic negotiated approaches to process planning and scheduling is presented for the integration of manufacturing process planning and scheduling.
文摘The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics(CFD)approach.The first applied model is a one-equation SGS model for large eddy simulation(LES)and the second one is the SST-SAS hybrid RANS-LES.These models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface(h/B)distances at two Reynolds numbers namely,2960 and 4740 based on the jet exit velocity(U_e)and the hydraulic diameter(2B).The predictions are compared with the experimental data in the literature and also the results from RANS k-εmodel.Comparisons show that both models can produce relatively good results.However,one-equation model(OEM)produced more accurate results especially at impingement region at lower jet-to-surface distances.In terms of heat transfer,the OEM also predicted better at different jet-to-surface spacings.It is also observed that both models show similar performance at higher h/B ratios.
文摘According to the China Statistical Yearbook divided eight consumption expenditure, I set food, clothing, housing and household equipment and services as residents basic living expenses, of China＇ s rural pension replacement rate level of demand is calculated. The financial revenue scale autoregressive model predicted 2010-2020, the scale of fiscal revenue, with Pratt ＆ Whitney type total pension should be of basic pension and substitution rate level of demand for pension accounts for fiscal revenue proportion of the international experience of fiscal income of 5% were measured and evaluated. The current basic pension in the short term to improve the life of the rural elderly has an important role, but the long-term need to continue to increase, should optimize the structure of fiscal expenditure.
基金Part of this work was supported by the National Science Foundation of China under Grant No. 51521003.
文摘For human assistance device, the particular properties are usually focused on high precision, compliant interaction, large torque generation and compactness of the mechanical system. To realize the high performance of lower extremity augmentation device, in this paper, we introduce a novel control methodology for compact elastic module. Based on the previous work, the elastic module consists of two parts, i.e., the proximal interaction module and the distal control module. To improve the compactness of the exoskeleton, we only employ the distal control module to achieve both purposes of precision force control and human intention recognition with physical human-machine interaction. In addition, a novel control methodology, so-called high precision data-driven force control with disturbance observer is adopted in this paper. To assess our proposed control methodology, we compare our novel force control with several other control methodologies on the lower extremity augmentation single leg exoskeleton system. The experiment shows a satisfying result and promising application feasibility of the proposed control methodology.
基金the National Natural Science Foundation of China
文摘A two dimensional model of the transient natural convection in a freezer is studied numerically by finite volume approach.The temperatures of the freezer outside surfaces and the evaporator vary in specified manners,which were taken from an experimental work.The fluid in the freezer is of the Bousinnesq type and the flow is assumed laminar,The transient heat conduction in the insulating layers and the temperature and velocity fields of the fluid are solved conjugately.The radiation heat transfer between the freezer inner surfaces is taken into account by using the additional source term method.The distributions of the local Nusselt number along the upper and lower surfaces of the evaporator and their average values in the period of periodically unsteady operation are calculated.Comparisons are made between the results with and without consideration of inner surface radiative heat transfer.It is found that the radiative heat transfer between the inner surfaces has a profound effect on the evaporator heat transfer characteristics.
