This paper investigates the dynamical behaviour of network traffic flow. Assume that trip rates may be influenced by the level of service on the network and travellers are willing to take a faster route. A discrete dy...This paper investigates the dynamical behaviour of network traffic flow. Assume that trip rates may be influenced by the level of service on the network and travellers are willing to take a faster route. A discrete dynamical model for the day-to-day adjustment process of route choice is presented. The model is then applied to a simple network for analysing the day-to-day behaviours of network flow. It finds that equilibrium is arrived if network flow consists of travellers not very sensitive to the differences of travel cost. Oscillations and chaos of network traffic flow are also found when travellers are sensitive to the travel cost and travel demand in a simple network.展开更多
Efficiently solving the user equilibrium traffic assignment problem with elastic demand(UE-TAPED)for transportation networks is a critical problem for transportation studies.Most existing UE-TAPED algorithms are desig...Efficiently solving the user equilibrium traffic assignment problem with elastic demand(UE-TAPED)for transportation networks is a critical problem for transportation studies.Most existing UE-TAPED algorithms are designed using a sequential computing scheme,which cannot take advantage of advanced parallel computing power.Therefore,this study focuses on model decomposition and parallelization,proposing an origin-based formulation for UE-TAPED and proving an equivalent reformulation of the original problem.Furthermore,the alternative direction method of multipliers(ADMM)is employed to decompose the original problem into independent link-based subproblems,which can solve large-scale problems with small storage space.In addition,to enhance the efficiency of our algorithm,the parallel computing technology with optimal parallel computing schedule is implemented to solve the link-based subproblems.Numerical experiments are performed to validate the computation efficiency of the proposed parallel algorithm.展开更多
This paper proposes the Trasfugen method for traffic assignment aimed at solving the user equilibrium problem.To this end,the method makes use of a genetic algorithm.A fuzzy system is proposed for controlling the muta...This paper proposes the Trasfugen method for traffic assignment aimed at solving the user equilibrium problem.To this end,the method makes use of a genetic algorithm.A fuzzy system is proposed for controlling the mutation and crossover rates of the genetic algorithm,and the corrective strategy is exploited for handling the equilibrium problem constraints.In the model,an approximation algorithm is proposed for obtaining the paths between the origin–destination pairs in the demand matrix.Unlike the traditional deterministic algorithm that has exponential time complexity,this approximation algorithm has polynomial time complexity and is executed much faster.Afterward,the Trasfugen method is applied to the urban network of Tehran metropolitan and the efficiency is investigated.Upon comparing the results obtained from the proposed model with those obtained from the conventional traffic assignment method,namely,the Frank–Wolfe method;it is shown that the proposed algorithm,while acting worse during the initial iterations,achieves better results in the subsequent iterations.Moreover,it prevents the occurrence of local optimal points as well as early/premature convergence,thus producing better results than the Frank–Wolfe algorithm.展开更多
针对CABO(Concurrent Architectures are Better Than One)网络体系结构下虚拟网内部路由协议可定制的特点设计了流量分配路由算法,对于运营带宽敏感业务的虚拟网络采用路由算法解决流量分配问题,提出一种新的指定路由机制,利用改进的...针对CABO(Concurrent Architectures are Better Than One)网络体系结构下虚拟网内部路由协议可定制的特点设计了流量分配路由算法,对于运营带宽敏感业务的虚拟网络采用路由算法解决流量分配问题,提出一种新的指定路由机制,利用改进的多商品流问题作为流量分配路由算法,以流量均衡、收益最大为分配目标;仿真实验结果表明,采用基于指定路由的流量分配路由机制较传统负载均衡路由算法获得的链路利用率更高、网络性能(丢包率、延迟)更好,并可接受更多的业务请求接入.展开更多
文摘This paper investigates the dynamical behaviour of network traffic flow. Assume that trip rates may be influenced by the level of service on the network and travellers are willing to take a faster route. A discrete dynamical model for the day-to-day adjustment process of route choice is presented. The model is then applied to a simple network for analysing the day-to-day behaviours of network flow. It finds that equilibrium is arrived if network flow consists of travellers not very sensitive to the differences of travel cost. Oscillations and chaos of network traffic flow are also found when travellers are sensitive to the travel cost and travel demand in a simple network.
基金supported by the National Natural Science Foundation of China(Nos.52302391,5202375,and 52131203)the Natural Science Foundation of Jiangsu Province,China(No.BK20210247)the Fundamental Research Funds for the Central Universities,China(No.2242022R40025).
文摘Efficiently solving the user equilibrium traffic assignment problem with elastic demand(UE-TAPED)for transportation networks is a critical problem for transportation studies.Most existing UE-TAPED algorithms are designed using a sequential computing scheme,which cannot take advantage of advanced parallel computing power.Therefore,this study focuses on model decomposition and parallelization,proposing an origin-based formulation for UE-TAPED and proving an equivalent reformulation of the original problem.Furthermore,the alternative direction method of multipliers(ADMM)is employed to decompose the original problem into independent link-based subproblems,which can solve large-scale problems with small storage space.In addition,to enhance the efficiency of our algorithm,the parallel computing technology with optimal parallel computing schedule is implemented to solve the link-based subproblems.Numerical experiments are performed to validate the computation efficiency of the proposed parallel algorithm.
文摘This paper proposes the Trasfugen method for traffic assignment aimed at solving the user equilibrium problem.To this end,the method makes use of a genetic algorithm.A fuzzy system is proposed for controlling the mutation and crossover rates of the genetic algorithm,and the corrective strategy is exploited for handling the equilibrium problem constraints.In the model,an approximation algorithm is proposed for obtaining the paths between the origin–destination pairs in the demand matrix.Unlike the traditional deterministic algorithm that has exponential time complexity,this approximation algorithm has polynomial time complexity and is executed much faster.Afterward,the Trasfugen method is applied to the urban network of Tehran metropolitan and the efficiency is investigated.Upon comparing the results obtained from the proposed model with those obtained from the conventional traffic assignment method,namely,the Frank–Wolfe method;it is shown that the proposed algorithm,while acting worse during the initial iterations,achieves better results in the subsequent iterations.Moreover,it prevents the occurrence of local optimal points as well as early/premature convergence,thus producing better results than the Frank–Wolfe algorithm.
文摘针对CABO(Concurrent Architectures are Better Than One)网络体系结构下虚拟网内部路由协议可定制的特点设计了流量分配路由算法,对于运营带宽敏感业务的虚拟网络采用路由算法解决流量分配问题,提出一种新的指定路由机制,利用改进的多商品流问题作为流量分配路由算法,以流量均衡、收益最大为分配目标;仿真实验结果表明,采用基于指定路由的流量分配路由机制较传统负载均衡路由算法获得的链路利用率更高、网络性能(丢包率、延迟)更好,并可接受更多的业务请求接入.
