The objective of the paper is to develop a new algorithm for numerical solution of dynamic elastic-plastic strain hardening/softening problems. The gradient dependent model is adopted in the numerical model to overcom...The objective of the paper is to develop a new algorithm for numerical solution of dynamic elastic-plastic strain hardening/softening problems. The gradient dependent model is adopted in the numerical model to overcome the result mesh-sensitivity problem in the dynamic strain softening or strain localization analysis. The equations for the dynamic elastic-plastic problems are derived in terms of the parametric variational principle, which is valid for associated, non-associated and strain softening plastic constitutive models in the finite element analysis. The precise integration method, which has been widely used for discretization in time domain of the linear problems, is introduced for the solution of dynamic nonlinear equations. The new algorithm proposed is based on the combination of the parametric quadratic programming method and the precise integration method and has all the advantages in both of the algorithms. Results of numerical examples demonstrate not only the validity, but also the advantages of the algorithm proposed for the numerical solution of nonlinear dynamic problems.展开更多
The elastic-plastic contact problem with rolling friction of wheel-rail is solved using the FE parametric quadratic programming method. Thus, the complex elastic-plastic contact problem can be calculated with high acc...The elastic-plastic contact problem with rolling friction of wheel-rail is solved using the FE parametric quadratic programming method. Thus, the complex elastic-plastic contact problem can be calculated with high accuracy and efficiency, while the Hertz＇s hypothesis and the elastic semi-space assumption are avoided. Based on the ‘one-point＇ contact calculation of wheel-rail, the computational model of ‘two-point＇ contact are established and calculated when the wheel flange is close to the rail. In the case of ‘two-point＇ contact, the changing laws of wheelrail contact are introduced and contact forces in various load cases are carefully analyzed. The main reason of wheel flange wear and rail side wear is found. Lubrication computational model of the wheel flange is constructed. Comparing with the result without lubrication, the contact force between wheel flange and rail decreases, which is beneficial for reducing the wear of wheel-rail.展开更多
This paper analyzes the problem of the design of envelopes for high-rise isolated residential buildings. The phenomenon of envelope creation appears in the early stages of the architectural design. Variables that infl...This paper analyzes the problem of the design of envelopes for high-rise isolated residential buildings. The phenomenon of envelope creation appears in the early stages of the architectural design. Variables that influence the final shape and size of such envelopes are then identified. This paper presents the state-of-the-art tools for the current solutions at the commercial and academic/scientific level. The variables identified in this research are the client＇s needs, the urban code and architectural practice, and their specific components for the final creation of a new decision support system tool based on the building information modeling （BIM） software platform, to facilitate the work in the project development and drawing production stages. This tool generates several options for building envelopes according to the parameters required by the city Zoning Planning Commission. These options then lead to deliver reliable data and a geometry that can be analyzed in a timely fashion by the engineers, builders, architects, government, and clients in the early stages of the building＇s design. The results show that use of specific information and communication technologies （ICT） tools in the early stages of a building design helps reduce the working time, increases confidence in the generated solution, and contributes to the exploration of alternatives in a short period of time.展开更多
The improvement of energy efficiency has played an important role in the global low-carbon economy and the sustainable development process.There are many methodologies for estimating energy efficiency in academia.This...The improvement of energy efficiency has played an important role in the global low-carbon economy and the sustainable development process.There are many methodologies for estimating energy efficiency in academia.This article introduces four frontier methods for energy efficiency evaluation:nonparametric data envelopment analysis(DEA),parametric linear programming,stochastic frontier analysis(SFA),and the meta-frontier approach.The advantages and disadvantages of these methods are discussed.Finally,suggestions for model selection in energy efficiency measurement are offered.展开更多
文摘The objective of the paper is to develop a new algorithm for numerical solution of dynamic elastic-plastic strain hardening/softening problems. The gradient dependent model is adopted in the numerical model to overcome the result mesh-sensitivity problem in the dynamic strain softening or strain localization analysis. The equations for the dynamic elastic-plastic problems are derived in terms of the parametric variational principle, which is valid for associated, non-associated and strain softening plastic constitutive models in the finite element analysis. The precise integration method, which has been widely used for discretization in time domain of the linear problems, is introduced for the solution of dynamic nonlinear equations. The new algorithm proposed is based on the combination of the parametric quadratic programming method and the precise integration method and has all the advantages in both of the algorithms. Results of numerical examples demonstrate not only the validity, but also the advantages of the algorithm proposed for the numerical solution of nonlinear dynamic problems.
基金supported by the National Natural Science Foundation of China(Nos.50605003 and 50875218)China Postdoctoral Science Foundation.
文摘The elastic-plastic contact problem with rolling friction of wheel-rail is solved using the FE parametric quadratic programming method. Thus, the complex elastic-plastic contact problem can be calculated with high accuracy and efficiency, while the Hertz＇s hypothesis and the elastic semi-space assumption are avoided. Based on the ‘one-point＇ contact calculation of wheel-rail, the computational model of ‘two-point＇ contact are established and calculated when the wheel flange is close to the rail. In the case of ‘two-point＇ contact, the changing laws of wheelrail contact are introduced and contact forces in various load cases are carefully analyzed. The main reason of wheel flange wear and rail side wear is found. Lubrication computational model of the wheel flange is constructed. Comparing with the result without lubrication, the contact force between wheel flange and rail decreases, which is beneficial for reducing the wear of wheel-rail.
文摘This paper analyzes the problem of the design of envelopes for high-rise isolated residential buildings. The phenomenon of envelope creation appears in the early stages of the architectural design. Variables that influence the final shape and size of such envelopes are then identified. This paper presents the state-of-the-art tools for the current solutions at the commercial and academic/scientific level. The variables identified in this research are the client＇s needs, the urban code and architectural practice, and their specific components for the final creation of a new decision support system tool based on the building information modeling （BIM） software platform, to facilitate the work in the project development and drawing production stages. This tool generates several options for building envelopes according to the parameters required by the city Zoning Planning Commission. These options then lead to deliver reliable data and a geometry that can be analyzed in a timely fashion by the engineers, builders, architects, government, and clients in the early stages of the building＇s design. The results show that use of specific information and communication technologies （ICT） tools in the early stages of a building design helps reduce the working time, increases confidence in the generated solution, and contributes to the exploration of alternatives in a short period of time.
基金financial support provided by the National Natural Science Foundation of China (Grant Nos.41461118 & 91746112)the National Social Science Foundation of China (Grant No.15ZDA054)
文摘The improvement of energy efficiency has played an important role in the global low-carbon economy and the sustainable development process.There are many methodologies for estimating energy efficiency in academia.This article introduces four frontier methods for energy efficiency evaluation:nonparametric data envelopment analysis(DEA),parametric linear programming,stochastic frontier analysis(SFA),and the meta-frontier approach.The advantages and disadvantages of these methods are discussed.Finally,suggestions for model selection in energy efficiency measurement are offered.
