This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of gua...This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of guaranteeing,under some proper non-restrictive initial conditions,the protection constraints control raised by the distance-to-go(moving authority)curve and automatic train protection in practice.A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains.The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability,no adaptations of unknown parameters,function approximation of unknown nonlinearities,and attenuation of external disturbances in the proposed control strategies.Finally,rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.展开更多
The constraints and the operations play an important role in database generalization.They guide and govern database generalization.The constraints are translation of the required conditions that should take into accou...The constraints and the operations play an important role in database generalization.They guide and govern database generalization.The constraints are translation of the required conditions that should take into account not only the objects and relationships among objects but also spatial data schema (classification and aggregation hierarchy) associated with the final existing database.The operations perform the actions of generalization in support of data reduction in the database.The constraints in database generalization are still lack of research.There is still the lack of frameworks to express the constraints and the operations on the basis of object_oriented data structure in database generalization.This paper focuses on the frameworks for generalization operations and constraints on the basis of object_oriented data structure in database generalization.The constraints as the attributes of the object and the operations as the methods of the object can be encapsulated in classes.They have the inheritance and polymorphism property.So the framework of the constraints and the operations which are based on object_oriented data structure can be easily understood and implemented.The constraint and the operations based on object_oriented database are proposed based on object_oriented database.The frameworks for generalization operations,constraints and relations among objects based on object_oriented data structure in database generalization are designed.The categorical database generalization is concentrated on in this paper.展开更多
This paper reviews existing approaches to the airport gate assignment problem （AGAP） and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize t...This paper reviews existing approaches to the airport gate assignment problem （AGAP） and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize the dispersion of gate idle time periods （to get robust optimization） while ensuring appropriate matching between the size of each aircraft and its assigned gate type and avoiding the potential hazard caused by gate apron operational conflict. Genetic algorithm is adopted to solve the problem, An illustrative example is given to show the effectiveness and efficiency of the algorithm. The algorithm performance is further demonstrated using data of a terminal from Beijing Capital International Airport （PEK）.展开更多
This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and man...This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and management of constraints.To protect the constraints,they should be buffered with time buffers,which protecting the system’s output from disruptions and fluctuations.Despite the importance of time buffers,the approaches to identifying the size of the time buffer in literature are very empirical.In this paper,a queuing-theory based method is applied to calculate the time buffer sizes.It provides a mathematically exact expression for the coefficient of variation of waiting time for Markov queues.It then applies the concept of isomorphism to approximate the variance of customer waiting time in a general queue.Simulation experiments are conducted to verify the accuracy of approximation.展开更多
The Nesterov accelerated dynamical approach serves as an essential tool for addressing convex optimization problems with accelerated convergence rates.Most previous studies in this field have primarily concentrated on...The Nesterov accelerated dynamical approach serves as an essential tool for addressing convex optimization problems with accelerated convergence rates.Most previous studies in this field have primarily concentrated on unconstrained smooth con-vex optimization problems.In this paper,on the basis of primal-dual dynamical approach,Nesterov accelerated dynamical approach,projection operator and directional gradient,we present two accelerated primal-dual projection neurodynamic approaches with time scaling to address convex optimization problems with smooth and nonsmooth objective functions subject to linear and set constraints,which consist of a second-order ODE(ordinary differential equation)or differential conclusion system for the primal variables and a first-order ODE for the dual vari-ables.By satisfying specific conditions for time scaling,we demonstrate that the proposed approaches have a faster conver-gence rate.This only requires assuming convexity of the objective function.We validate the effectiveness of our proposed two accel-erated primal-dual projection neurodynamic approaches through numerical experiments.展开更多
“双碳”背景下,异质能源的耦合加剧迫使综合能源系统(integrated energy system, IES)拓扑朝着更复杂、更灵活的方向不断演变。然而,现有优化调度方法对非欧网络拓扑知识及其异质潮流约束考虑不足。针对这一问题,提出一种基于图强化学...“双碳”背景下,异质能源的耦合加剧迫使综合能源系统(integrated energy system, IES)拓扑朝着更复杂、更灵活的方向不断演变。然而,现有优化调度方法对非欧网络拓扑知识及其异质潮流约束考虑不足。针对这一问题,提出一种基于图强化学习的综合能源系统优化调度方法。首先,基于图理论在保证节点多样状态的情况下,将异质能源网络拓扑转换为网络图模型。其次,通过建立基于真实图映射的状态-动作-奖励的框架,利用图强化学习的方法学习图模型的非欧拓扑信息,将异质潮流知识加入系统节点运行状态,从而实现IES的安全优化调度。最后,利用某工业园区的真实数据进行仿真验证,所提方法相对于传统方法有效缓解了节点电压越限的问题。结果表明,所提方法能够在考虑IES真实拓扑运行状态信息和异质潮流安全的情况下实现IES的优化调度。展开更多
Superconvergence and recovery a posteriori error estimates of the finite element ap- proximation for general convex optimal control problems are investigated in this paper. We obtain the superconvergence properties of...Superconvergence and recovery a posteriori error estimates of the finite element ap- proximation for general convex optimal control problems are investigated in this paper. We obtain the superconvergence properties of finite element solutions, and by using the superconvergence results we get recovery a posteriori error estimates which are asymptotically exact under some regularity conditions. Some numerical examples are provided to verify the theoretical results.展开更多
基金supported jointly by the National Natural Science Foundation of China(61703033,61790573)Beijing Natural Science Foundation(4192046)+1 种基金Fundamental Research Funds for Central Universities(2018JBZ002)State Key Laboratory of Rail Traffic Control and Safety(RCS2018ZT013),Beijing Jiaotong University
文摘This paper addresses the control design for automatic train operation of high-speed trains with protection constraints.A new resilient nonlinear gain-based feedback control approach is proposed,which is capable of guaranteeing,under some proper non-restrictive initial conditions,the protection constraints control raised by the distance-to-go(moving authority)curve and automatic train protection in practice.A new hyperbolic tangent function-based model is presented to mimic the whole operation process of high-speed trains.The proposed feedback control methods are easily implementable and computationally inexpensive because the presence of only two feedback gains guarantee satisfactory tracking performance and closed-loop stability,no adaptations of unknown parameters,function approximation of unknown nonlinearities,and attenuation of external disturbances in the proposed control strategies.Finally,rigorous proofs and comparative simulation results are given to demonstrate the effectiveness of the proposed approaches.
文摘The constraints and the operations play an important role in database generalization.They guide and govern database generalization.The constraints are translation of the required conditions that should take into account not only the objects and relationships among objects but also spatial data schema (classification and aggregation hierarchy) associated with the final existing database.The operations perform the actions of generalization in support of data reduction in the database.The constraints in database generalization are still lack of research.There is still the lack of frameworks to express the constraints and the operations on the basis of object_oriented data structure in database generalization.This paper focuses on the frameworks for generalization operations and constraints on the basis of object_oriented data structure in database generalization.The constraints as the attributes of the object and the operations as the methods of the object can be encapsulated in classes.They have the inheritance and polymorphism property.So the framework of the constraints and the operations which are based on object_oriented data structure can be easily understood and implemented.The constraint and the operations based on object_oriented database are proposed based on object_oriented database.The frameworks for generalization operations,constraints and relations among objects based on object_oriented data structure in database generalization are designed.The categorical database generalization is concentrated on in this paper.
文摘This paper reviews existing approaches to the airport gate assignment problem （AGAP） and presents an optimization model for the problem considering operational safety constraints. The main objective is to minimize the dispersion of gate idle time periods （to get robust optimization） while ensuring appropriate matching between the size of each aircraft and its assigned gate type and avoiding the potential hazard caused by gate apron operational conflict. Genetic algorithm is adopted to solve the problem, An illustrative example is given to show the effectiveness and efficiency of the algorithm. The algorithm performance is further demonstrated using data of a terminal from Beijing Capital International Airport （PEK）.
文摘This paper uses quantitative methods to estimate the size of the time buffer in lean operations controlled by the Theory of Constraints(TOC).The main focus of the operations system of TOC is the identification and management of constraints.To protect the constraints,they should be buffered with time buffers,which protecting the system’s output from disruptions and fluctuations.Despite the importance of time buffers,the approaches to identifying the size of the time buffer in literature are very empirical.In this paper,a queuing-theory based method is applied to calculate the time buffer sizes.It provides a mathematically exact expression for the coefficient of variation of waiting time for Markov queues.It then applies the concept of isomorphism to approximate the variance of customer waiting time in a general queue.Simulation experiments are conducted to verify the accuracy of approximation.
基金supported by the National Natural Science Foundation of China(62176218,62176027)the Fundamental Research Funds for the Central Universities(XDJK2020TY003)the Funds for Chongqing Talent Plan(cstc2024ycjh-bgzxm0082)。
文摘The Nesterov accelerated dynamical approach serves as an essential tool for addressing convex optimization problems with accelerated convergence rates.Most previous studies in this field have primarily concentrated on unconstrained smooth con-vex optimization problems.In this paper,on the basis of primal-dual dynamical approach,Nesterov accelerated dynamical approach,projection operator and directional gradient,we present two accelerated primal-dual projection neurodynamic approaches with time scaling to address convex optimization problems with smooth and nonsmooth objective functions subject to linear and set constraints,which consist of a second-order ODE(ordinary differential equation)or differential conclusion system for the primal variables and a first-order ODE for the dual vari-ables.By satisfying specific conditions for time scaling,we demonstrate that the proposed approaches have a faster conver-gence rate.This only requires assuming convexity of the objective function.We validate the effectiveness of our proposed two accel-erated primal-dual projection neurodynamic approaches through numerical experiments.
文摘“双碳”背景下,异质能源的耦合加剧迫使综合能源系统(integrated energy system, IES)拓扑朝着更复杂、更灵活的方向不断演变。然而,现有优化调度方法对非欧网络拓扑知识及其异质潮流约束考虑不足。针对这一问题,提出一种基于图强化学习的综合能源系统优化调度方法。首先,基于图理论在保证节点多样状态的情况下,将异质能源网络拓扑转换为网络图模型。其次,通过建立基于真实图映射的状态-动作-奖励的框架,利用图强化学习的方法学习图模型的非欧拓扑信息,将异质潮流知识加入系统节点运行状态,从而实现IES的安全优化调度。最后,利用某工业园区的真实数据进行仿真验证,所提方法相对于传统方法有效缓解了节点电压越限的问题。结果表明,所提方法能够在考虑IES真实拓扑运行状态信息和异质潮流安全的情况下实现IES的优化调度。
基金supported by Guangdong Provincial"Zhujiang Scholar Award Project"National Science Foundation of China 10671163+2 种基金the National Basic Research Program under the Grant 2005CB321703Scientific Research Fund of Hunan Provincial Education Department 06A069Guangxi Natural Science Foundation 0575029
文摘Superconvergence and recovery a posteriori error estimates of the finite element ap- proximation for general convex optimal control problems are investigated in this paper. We obtain the superconvergence properties of finite element solutions, and by using the superconvergence results we get recovery a posteriori error estimates which are asymptotically exact under some regularity conditions. Some numerical examples are provided to verify the theoretical results.
