In the process of numerical control machining simulation,the workpiece surface is usually described with the uniform triangular mesh model.To alleviate the contradiction between the simulation speed and accuracy in th...In the process of numerical control machining simulation,the workpiece surface is usually described with the uniform triangular mesh model.To alleviate the contradiction between the simulation speed and accuracy in this model,two improved methods,i.e.,the local refinement triangular mesh modeling method and the adaptive triangular mesh modeling method were presented.The simulation results show that when the final shape of the workpiece is known and its mathematic representation is simple,the local refinement triangular mesh modeling method is preferred;when the final shape of the workpiece is unknown and its mathematic description is complicated,the adaptive triangular mesh modeling method is more suitable.The experimental results show that both methods are more targeted and practical and can meet the requirements of real-time and precision in simulation.展开更多
A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum （-0.2 nPa） in the ioni...A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum （-0.2 nPa） in the ionization region is obtained by using multiple ultrahigh vacuum pumps. Compared with similar instruments built previously by others~ the H2, CH4 background in the ionization region can be reduced by about two orders of magnitude, and other residual gases in the ionization region can be reduced by about an order of magnitude. Therefore, the signal-to-noise ratio for the temperature programmed desorption （TPD） and time of flight （TOF） spectra is substantially enhanced, making experimental studies of pho- tocatalytic processes on surfaces much easier. In this work, we describe the new apparatus in detail and present some preliminary studies on the photo-induced oxygen vacancy defects on TiO2（110） at 266 nm by using the TPD and TOF methods. Preliminary results suggest that the apparatus is a powerful tool for studying kinetics and mechanism of photochemical processes.展开更多
Virtual reality system has low cost and high efficiency advantages by many virtual reality research units and individuals. Virtual reality technology will be used in the machining process, and can demonstrate the mach...Virtual reality system has low cost and high efficiency advantages by many virtual reality research units and individuals. Virtual reality technology will be used in the machining process, and can demonstrate the machining process, discussed the processing scheme, to improve the quality of products. At the same time, the combination of modem education technology and virtual reality technology in the teaching, establishment of virtual machine and virtual machining simulation environment, that can improve the quality of teaching.展开更多
The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model ...The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model to study the operating performance of the induction motor system.This model consists of non-linear time varying electromagnetic field equations,mechanical wave equations of sucker rods and non-linear coupling equation of reducer and four-bar linkage.The equations are numerically solved by combining time-step finite element method(TS-FEM),finite difference method(FDM),a linear dimension reduction method and the Newton-Raphson method.Simulation results,which are validated by experiments,reveal the influence of the fluctuating potential load on magnetic field distributions,stator and rotor currents,the input power and the power factor.The model and simulation results provide theoretical and technical supports for subsequent researches on model simplification and energy saving technologies.展开更多
We consider the relevance of computer hardware and simulations not only to science and technology but also to social life. Evolutionary processes are part of all we know, from the physical and inanimate world to the s...We consider the relevance of computer hardware and simulations not only to science and technology but also to social life. Evolutionary processes are part of all we know, from the physical and inanimate world to the simplest or most complex biological system. Evolution is manifested by land mark discoveries which deeply affect our social life. Demographic pressure, demand for improved living standards and devastation of the natural environment pose new and complex challenges. We believe that the implementation of new computational models based on the latest scientific methodology can provide a reasonable chance of overcoming today's social problems. To ensure this goal, however, we need a change of mindset, placing findings obtained from modern science above traditional concepts and beliefs. In particular, the type of modeling used with success in computational sciences must be extended to allow simulations of novel models for social life.展开更多
基金Project(60772089) supported by the National Natural Science Foundation of ChinaProject(20080440939) supported by the China Postdoctoral Science Foundation
文摘In the process of numerical control machining simulation,the workpiece surface is usually described with the uniform triangular mesh model.To alleviate the contradiction between the simulation speed and accuracy in this model,two improved methods,i.e.,the local refinement triangular mesh modeling method and the adaptive triangular mesh modeling method were presented.The simulation results show that when the final shape of the workpiece is known and its mathematic representation is simple,the local refinement triangular mesh modeling method is preferred;when the final shape of the workpiece is unknown and its mathematic description is complicated,the adaptive triangular mesh modeling method is more suitable.The experimental results show that both methods are more targeted and practical and can meet the requirements of real-time and precision in simulation.
文摘A surface photocatalysis-TPD apparatus devoted to studying kinetics and mechanism of pho- tocatalytic processes with various signal crystal surfaces has been constructed. Extremely high vacuum （-0.2 nPa） in the ionization region is obtained by using multiple ultrahigh vacuum pumps. Compared with similar instruments built previously by others~ the H2, CH4 background in the ionization region can be reduced by about two orders of magnitude, and other residual gases in the ionization region can be reduced by about an order of magnitude. Therefore, the signal-to-noise ratio for the temperature programmed desorption （TPD） and time of flight （TOF） spectra is substantially enhanced, making experimental studies of pho- tocatalytic processes on surfaces much easier. In this work, we describe the new apparatus in detail and present some preliminary studies on the photo-induced oxygen vacancy defects on TiO2（110） at 266 nm by using the TPD and TOF methods. Preliminary results suggest that the apparatus is a powerful tool for studying kinetics and mechanism of photochemical processes.
文摘Virtual reality system has low cost and high efficiency advantages by many virtual reality research units and individuals. Virtual reality technology will be used in the machining process, and can demonstrate the machining process, discussed the processing scheme, to improve the quality of products. At the same time, the combination of modem education technology and virtual reality technology in the teaching, establishment of virtual machine and virtual machining simulation environment, that can improve the quality of teaching.
基金supported by the National Natural Science Foundation of China(Grant No.51307050)
文摘The induction motor system with fluctuating potential loads is a non-linear complex electro-mechanical system.With beam pumping motors as an example,this paper proposes a multiple factor non-linear mathematical model to study the operating performance of the induction motor system.This model consists of non-linear time varying electromagnetic field equations,mechanical wave equations of sucker rods and non-linear coupling equation of reducer and four-bar linkage.The equations are numerically solved by combining time-step finite element method(TS-FEM),finite difference method(FDM),a linear dimension reduction method and the Newton-Raphson method.Simulation results,which are validated by experiments,reveal the influence of the fluctuating potential load on magnetic field distributions,stator and rotor currents,the input power and the power factor.The model and simulation results provide theoretical and technical supports for subsequent researches on model simplification and energy saving technologies.
文摘We consider the relevance of computer hardware and simulations not only to science and technology but also to social life. Evolutionary processes are part of all we know, from the physical and inanimate world to the simplest or most complex biological system. Evolution is manifested by land mark discoveries which deeply affect our social life. Demographic pressure, demand for improved living standards and devastation of the natural environment pose new and complex challenges. We believe that the implementation of new computational models based on the latest scientific methodology can provide a reasonable chance of overcoming today's social problems. To ensure this goal, however, we need a change of mindset, placing findings obtained from modern science above traditional concepts and beliefs. In particular, the type of modeling used with success in computational sciences must be extended to allow simulations of novel models for social life.
