Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is ...Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.展开更多
The exploitation of competent electrocatalysts is a key issue of the broad application of many promising electrochemical processes,including the hydrogen evolution reaction(HER),the oxygen evolution reaction(OER),the ...The exploitation of competent electrocatalysts is a key issue of the broad application of many promising electrochemical processes,including the hydrogen evolution reaction(HER),the oxygen evolution reaction(OER),the oxygen reduction reaction(ORR),the CO_(2) reduction reaction(CO_(2)RR)and the nitrogen reduction reaction(NRR).The traditional searches for good electrocatalysts rely on the trial-and-error approaches,which are typically tedious and inefficient.In the past decades,some fundamental principles,activity descriptors and catalytic mechanisms have been established to accelerate the discovery of advanced electrocatalysts.Hence,it is time to summarize these theory-related research advances that unravel the structure-performance relationships and enables predictive ability in electrocatalysis studies.In this review,we summarize some basic aspects of catalytic theories that are commonly used in the design of electrocatalysts(e.g.,Sabatier principle,d-band theory,adsorption-energy scaling relation,activity descriptors)and their relevance.Then,we briefly introduced the fundamental mechanisms and central challenges of HER,OER,ORR,CO_(2)RR and NRR electrocatalysts,and highlight the theory-based efforts used to address the challenges facing these electrocatalysis processes.Finally,we propose the key challenges and opportunities of theory-driven electrocatalysis on their future.展开更多
In this work, by means of a new more general ansatz and the symbolic computation system Maple, we extend the Riccati equation rational expansion method [Chaos, Solitons ＆ Fractals 25 （2005） 1019] to uniformly const...In this work, by means of a new more general ansatz and the symbolic computation system Maple, we extend the Riccati equation rational expansion method [Chaos, Solitons ＆ Fractals 25 （2005） 1019] to uniformly construct a series of stochastic nontravelling wave solutions for nonlinear stochastic evolution equation. To illustrate the effectiveness of our method, we take the stochastic mKdV equation as an example, and successfully construct some new and more general solutions including a series of rational formal nontraveling wave and coefficient functions＇ soliton-like solution.s and trigonometric-like function solutions. The method can also be applied to solve other nonlinear stochastic evolution equation or equations.展开更多
The homogenization of a class of degenerate quasilinear parabolic equations is studied. The Ap weight theory and the classical compensated compactness method are incorporated to obtain the homogenized equation.
In this paper we propose an algorithm based on the BFGS Quasi-Newton method to solve a linear program. The choice of this method is justified by its theoretical efficiency, the ease to determine a descent direction an...In this paper we propose an algorithm based on the BFGS Quasi-Newton method to solve a linear program. The choice of this method is justified by its theoretical efficiency, the ease to determine a descent direction and its fast convergence towards an optimal solution. Our proposed method is compared with Newton＇s method for linear program named lpnew, widely used as an optimization algorithm for classification problems.展开更多
We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniquen...We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniqueness and nonnegativeness of solutions when the principal operator is monotone and the nonlinearity is nonincreasing. Our operator is of the most general form containing all previous ones and we also weaken assumptions on the operator and the nonlinearity to get the above results. Moreover, we do not impose the restricted condition on p(x) and the uniform monotonicity of the operator to show the existence of three distinct solutions.展开更多
The global robust output regulation problem of the output feedback systems has been extensively studied under various assumptions of the complexity and uncertainty. All these approaches boil down to a stabilization pr...The global robust output regulation problem of the output feedback systems has been extensively studied under various assumptions of the complexity and uncertainty. All these approaches boil down to a stabilization problem of a so-called augmented extended system. This paper will describe an alternative approach which converts the original problem into a stabilization problem of a so-called extended augmented system. As the extended augmented system is somewhat simpler than the augmented extended system, this alternative approach is also simpler than the first approach.展开更多
基金Project(51375029)supported by the National Natural Science Foundation of ChinaProject(20091102120038)supported by Specialized Research Fund for Doctoral Program of Higher Education of China
文摘Variable pump driving variable motor(VPDVM) is the future development trend of the hydraulic transmission of an unmanned ground vehicle(UGV).VPDVM is a dual-input single-output nonlinear system with coupling,which is difficult to control.High pressure automatic variables bang-bang(HABB) was proposed to achieve the desired motor speed.First,the VPDVM nonlinear mathematic model was introduced,then linearized by feedback linearization theory,and the zero-dynamic stability was proved.The HABB control algorithm was proposed for VPDVM,in which the variable motor was controlled by high pressure automatic variables(HA) and the variable pump was controlled by bang-bang.Finally,simulation of VPDVM controlled by HABB was developed.Simulation results demonstrate the HABB can implement the desired motor speed rapidly and has strong robustness against the variations of desired motor speed,load and pump speed.
文摘The exploitation of competent electrocatalysts is a key issue of the broad application of many promising electrochemical processes,including the hydrogen evolution reaction(HER),the oxygen evolution reaction(OER),the oxygen reduction reaction(ORR),the CO_(2) reduction reaction(CO_(2)RR)and the nitrogen reduction reaction(NRR).The traditional searches for good electrocatalysts rely on the trial-and-error approaches,which are typically tedious and inefficient.In the past decades,some fundamental principles,activity descriptors and catalytic mechanisms have been established to accelerate the discovery of advanced electrocatalysts.Hence,it is time to summarize these theory-related research advances that unravel the structure-performance relationships and enables predictive ability in electrocatalysis studies.In this review,we summarize some basic aspects of catalytic theories that are commonly used in the design of electrocatalysts(e.g.,Sabatier principle,d-band theory,adsorption-energy scaling relation,activity descriptors)and their relevance.Then,we briefly introduced the fundamental mechanisms and central challenges of HER,OER,ORR,CO_(2)RR and NRR electrocatalysts,and highlight the theory-based efforts used to address the challenges facing these electrocatalysis processes.Finally,we propose the key challenges and opportunities of theory-driven electrocatalysis on their future.
基金The author would like to thank the referees very much for their careful reading of the manuscript and many valuable suggestions.
文摘In this work, by means of a new more general ansatz and the symbolic computation system Maple, we extend the Riccati equation rational expansion method [Chaos, Solitons ＆ Fractals 25 （2005） 1019] to uniformly construct a series of stochastic nontravelling wave solutions for nonlinear stochastic evolution equation. To illustrate the effectiveness of our method, we take the stochastic mKdV equation as an example, and successfully construct some new and more general solutions including a series of rational formal nontraveling wave and coefficient functions＇ soliton-like solution.s and trigonometric-like function solutions. The method can also be applied to solve other nonlinear stochastic evolution equation or equations.
基金the Foundations of Returned Overseas Chinese Education Ministry and the Key Teachers Foundation of Chongqing University.
文摘The homogenization of a class of degenerate quasilinear parabolic equations is studied. The Ap weight theory and the classical compensated compactness method are incorporated to obtain the homogenized equation.
文摘In this paper we propose an algorithm based on the BFGS Quasi-Newton method to solve a linear program. The choice of this method is justified by its theoretical efficiency, the ease to determine a descent direction and its fast convergence towards an optimal solution. Our proposed method is compared with Newton＇s method for linear program named lpnew, widely used as an optimization algorithm for classification problems.
基金supported by the National Research Foundation of Korea Grant Funded by the Korea Government (Grant No. NRF-2015R1D1A3A01019789)
文摘We show the existence and multiplicity of solutions to degenerate p(x)-Laplace equations with Leray-Lions type operators using direct methods and critical point theories in Calculus of Variations and prove the uniqueness and nonnegativeness of solutions when the principal operator is monotone and the nonlinearity is nonincreasing. Our operator is of the most general form containing all previous ones and we also weaken assumptions on the operator and the nonlinearity to get the above results. Moreover, we do not impose the restricted condition on p(x) and the uniform monotonicity of the operator to show the existence of three distinct solutions.
基金The work described in this paper was supported in part by a grant from the Research Grants Council of the Hong Kong Special Administration Region （Project No. CUHK412305） and in part by National Natural Science Foundations of China under grant No. 60374038.
文摘The global robust output regulation problem of the output feedback systems has been extensively studied under various assumptions of the complexity and uncertainty. All these approaches boil down to a stabilization problem of a so-called augmented extended system. This paper will describe an alternative approach which converts the original problem into a stabilization problem of a so-called extended augmented system. As the extended augmented system is somewhat simpler than the augmented extended system, this alternative approach is also simpler than the first approach.
