The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway reg...The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway regularity of two stages 6： 00--7：00 and 7： 00--9：00 is comparatively analyzed, and it is found that both the traffic conditions and the passenger demand affect headway regularity. A bus arrival model, which assumes that the dwell time of a bus is linear in headway, is built to probe the effect of scheduled headway, and the model is simulated by Matlab. The simulation results reveal that the departure intervals and fluctuations affect headway regularity. Longer intervals and less fluctuation mean higher regularity of headway. And, the fluctuation has a more obvious influence on headway regularity than the interval. Controlling the fluctuations of scheduled headway can effectively raise the regularity of headway and improve the level of public transport service.展开更多
Compared with front engine vehicle, the windward side’s flow field in cooling model of rear engine bus is complicated and it can’t be calculated by means of 1D model. For this problem, this paper has used Star-CCM t...Compared with front engine vehicle, the windward side’s flow field in cooling model of rear engine bus is complicated and it can’t be calculated by means of 1D model. For this problem, this paper has used Star-CCM to build a 3D simulation model of cooling system, engine compartment and complete vehicle. Then, it had a 1D/3D coupling calculation on cooling system with Kuli software. It could be helpful in the optimization design of the flow field of rear engine compartment and optimization match of cooling system.展开更多
To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines...To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines the variable lane with the bus priority pre-signal,and realizes the left-turning bus priority without causing great impact on other vehicles.To validate the effectiveness of the method,the VBAL scheme was compared with the single left-turn lane scheme(SLTL)and the double left-turn lane scheme(DLTL).On this basis,the delay change calculation model of left-turning buses and through vehicles were established by the cumulative curve graphic method.The influence of vehicle proportion and green split on the model was studied through sensitivity analysis.The results show that VBAL can reduce the delay of left-turning bus and the increase of through vehicle delay to the greatest extent.Finally,the scheme was applied to a real-world intersection,and the results demonstrate the effectiveness and advantage of the VBAL scheme.展开更多
In high-frequency bus services,maintaining the service regularity is a critical issue.The service regularity is directly related to the excessive waiting times(EWT) of passengers at bus stops.In a regular service,the ...In high-frequency bus services,maintaining the service regularity is a critical issue.The service regularity is directly related to the excessive waiting times(EWT) of passengers at bus stops.In a regular service,the EWT is minimized resulting in even headways between consecutive buses of the same line.In this study,we propose the combined use of rescheduling and bus holding to improve passengers’ excessive waiting times.We model the dynamic rescheduling and bus holding problem as an integer nonlinear program(INLP) and we prove its NP-hardness.Our model considers the constraints of the original timetable e an issue that is usually neglected from most dynamic control methods.Given the NP-hardness of our mathematical program,we introduce a problem-specific heuristic to explore efficiently the solution space.The convergence rate of the proposed heuristic is tested against other solution methods,including simulated annealing with linear cooling,hill climbing and branch and bound with multi-start sequential quadratic programming.In addition,simulations with the use of actual operational data from a major bus operator in Asia Pacific demonstrate an up to 35% potential EWT improvement for a minor increase of 6% to the travel times of onboard passengers.展开更多
Multi-objective optimization of urban bus network can help improve operation efficiency of the transit system and develop strategies for reducing urban traffic congestion in China. The work used cumulative prospect th...Multi-objective optimization of urban bus network can help improve operation efficiency of the transit system and develop strategies for reducing urban traffic congestion in China. The work used cumulative prospect theory, currently the most influential model for decision under uncertainty,to optimize urban bus network. To achieve the research objective, the work developed the theoretical framework of urban bus network optimization, including optimization principle, optimization objectives and constraints. Furthermore, optimization objectives could comprehensively reflect expectations of passengers and bus companies from the dimension of time, space and value. It is more scientific and reasonable compared with only one stakeholder or dimension alone in the previous studies. In addition,the technique for order preference by similarity to ideal solution(TOPSIS) was used to determine the positive and negative ideal alternative. The correlations between the optimization alternatives and the ideal alternatives were estimated by grey relational analysis simultaneously. The cumulative prospect theory(CPT) was used to determine the best alternative by comparing comprehensive prospect value of every alternative, accurately describing decision-making behavior compared with expected utility theory in actual life. Finally, Case of Xi'an showed that the method can better adjust the bus network,and the optimization solution is more reasonable to meet the actual needs.展开更多
Mass Customization and global economic collaboration drives the product development and management beyond internal enterprise to cover the whole product value chain. To meet such requirement, a strategy approach focus...Mass Customization and global economic collaboration drives the product development and management beyond internal enterprise to cover the whole product value chain. To meet such requirement, a strategy approach focusing on data organization for product lifecycle management was promoted. The approach takes product platform as the base, view engine and rule-based access as data access mechanism, and integration and collaboration bus as a enabler to allow participants involved in product lifecycle to get convenient, WEB-based access to the internal and external content, applications, and services.展开更多
基金The National Basic Research Program of China(973 Program)(No.2012CB725402)the National Natural Science Foundation of China(No.50978057)Program of Scientific Innovation Research of College Graduate in Jiangsu Province(No.CXLX12_0108)
文摘The common phenomenon of uneven headway in bus service is explored based on the automatic vehicle location （AVL） data of Route 2 in Yichun City of Jiangxi province from 6：00 to 9：00 in the morning. The headway regularity of two stages 6： 00--7：00 and 7： 00--9：00 is comparatively analyzed, and it is found that both the traffic conditions and the passenger demand affect headway regularity. A bus arrival model, which assumes that the dwell time of a bus is linear in headway, is built to probe the effect of scheduled headway, and the model is simulated by Matlab. The simulation results reveal that the departure intervals and fluctuations affect headway regularity. Longer intervals and less fluctuation mean higher regularity of headway. And, the fluctuation has a more obvious influence on headway regularity than the interval. Controlling the fluctuations of scheduled headway can effectively raise the regularity of headway and improve the level of public transport service.
文摘Compared with front engine vehicle, the windward side’s flow field in cooling model of rear engine bus is complicated and it can’t be calculated by means of 1D model. For this problem, this paper has used Star-CCM to build a 3D simulation model of cooling system, engine compartment and complete vehicle. Then, it had a 1D/3D coupling calculation on cooling system with Kuli software. It could be helpful in the optimization design of the flow field of rear engine compartment and optimization match of cooling system.
基金National Key R&D Program of China(No.2019YFB1600501)Scientific and Technological Developing Project of Jilin Province(No.20190201107JC).
文摘To reduce the delay of left-turning buses and improve the traffic efficiency at signalized intersections,a novel variable bus approach lane(VBAL)control method based on bus pre-signals is proposed.This method combines the variable lane with the bus priority pre-signal,and realizes the left-turning bus priority without causing great impact on other vehicles.To validate the effectiveness of the method,the VBAL scheme was compared with the single left-turn lane scheme(SLTL)and the double left-turn lane scheme(DLTL).On this basis,the delay change calculation model of left-turning buses and through vehicles were established by the cumulative curve graphic method.The influence of vehicle proportion and green split on the model was studied through sensitivity analysis.The results show that VBAL can reduce the delay of left-turning bus and the increase of through vehicle delay to the greatest extent.Finally,the scheme was applied to a real-world intersection,and the results demonstrate the effectiveness and advantage of the VBAL scheme.
文摘In high-frequency bus services,maintaining the service regularity is a critical issue.The service regularity is directly related to the excessive waiting times(EWT) of passengers at bus stops.In a regular service,the EWT is minimized resulting in even headways between consecutive buses of the same line.In this study,we propose the combined use of rescheduling and bus holding to improve passengers’ excessive waiting times.We model the dynamic rescheduling and bus holding problem as an integer nonlinear program(INLP) and we prove its NP-hardness.Our model considers the constraints of the original timetable e an issue that is usually neglected from most dynamic control methods.Given the NP-hardness of our mathematical program,we introduce a problem-specific heuristic to explore efficiently the solution space.The convergence rate of the proposed heuristic is tested against other solution methods,including simulated annealing with linear cooling,hill climbing and branch and bound with multi-start sequential quadratic programming.In addition,simulations with the use of actual operational data from a major bus operator in Asia Pacific demonstrate an up to 35% potential EWT improvement for a minor increase of 6% to the travel times of onboard passengers.
基金supported by China’s National Key Basic Research Program under Grant No.2012CB725400China’s National Natural Science Fund Key Research Program under Grant No.51338003+2 种基金Key Cultivating Plan of Xi’an University of Architecture and Technology for Discipline Construction under Grant No.XK201213Talents Training Fund Program of Xi’an University of Architecture and Technology for Cultivating Discipline Construction under Grant No.XK201101Youth Talent Fund of Xi’an University of Architecture and Technology under Grant No.DB01138
文摘Multi-objective optimization of urban bus network can help improve operation efficiency of the transit system and develop strategies for reducing urban traffic congestion in China. The work used cumulative prospect theory, currently the most influential model for decision under uncertainty,to optimize urban bus network. To achieve the research objective, the work developed the theoretical framework of urban bus network optimization, including optimization principle, optimization objectives and constraints. Furthermore, optimization objectives could comprehensively reflect expectations of passengers and bus companies from the dimension of time, space and value. It is more scientific and reasonable compared with only one stakeholder or dimension alone in the previous studies. In addition,the technique for order preference by similarity to ideal solution(TOPSIS) was used to determine the positive and negative ideal alternative. The correlations between the optimization alternatives and the ideal alternatives were estimated by grey relational analysis simultaneously. The cumulative prospect theory(CPT) was used to determine the best alternative by comparing comprehensive prospect value of every alternative, accurately describing decision-making behavior compared with expected utility theory in actual life. Finally, Case of Xi'an showed that the method can better adjust the bus network,and the optimization solution is more reasonable to meet the actual needs.
文摘Mass Customization and global economic collaboration drives the product development and management beyond internal enterprise to cover the whole product value chain. To meet such requirement, a strategy approach focusing on data organization for product lifecycle management was promoted. The approach takes product platform as the base, view engine and rule-based access as data access mechanism, and integration and collaboration bus as a enabler to allow participants involved in product lifecycle to get convenient, WEB-based access to the internal and external content, applications, and services.
