In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed a...In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.展开更多
A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full...A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full load, and the changing value of each parameter with front wheel fluctuation to build a front suspension model for optimization analysis based on the multi-body dynamic (MD) theory. The original suspension is optimized with this model, and the variation law of each parameter with front wheel fluctuation is obtained. The results of a case study demonstrate that the front wheel orientation parameters of the optimized vehicle are reasonable under typical conditions and the variation of each parameter is in an ideal range with the wheel fluctuating within 40 mm. In addition, the driving performance is improved greatly in the road test and practical use.展开更多
The development of GPS （global positioning system） receiver now can be integrated on a smartphone. GPS receiver on smartphones has been developed for location-based applications. Smartphones are very suitable to be ...The development of GPS （global positioning system） receiver now can be integrated on a smartphone. GPS receiver on smartphones has been developed for location-based applications. Smartphones are very suitable to be used as an experimental tool, because smartphones are usually equipped with various types of sensors. This paper proposes a model observation vehicle speed on a road section based on the GPS data on the smartphone. Observations made by calculating the speed of the speed of vehicles moving through the data transfer at the GPS location of the smartphone, the data are then sent periodically to the server and server processing and storage of vehicle speed data. After tested with test reliability indicators use RMSE, observations with model observations speed, speed based on GPS data on a smartphone are relevant when compared with the speed directly from the vehicle＇s speedometer with the difference between the value of the difference of speed that is 3.1785 km/h.展开更多
The use of AVL （automatic vehicle locator） systems has increased considerably. By using an AVL system, it is possible to know vehicle positions at the dispatch center, which allows the use of several applications, s...The use of AVL （automatic vehicle locator） systems has increased considerably. By using an AVL system, it is possible to know vehicle positions at the dispatch center, which allows the use of several applications, such as safety and security, logistics, and emergency response. High communication and data storage costs, however, lead to a low position update rate with the AVL products available, causing poor track representation, and making the route determined by the vehicle in urban areas almost illegible. This paper proposes a new approach by using intelligent techniques to choose the best position update moment to improve track representations. The principle underlying these techniques is based on vehicle status analysis （speed, direction and timing）, which tries to determine when a position update is required, in order to better represent the path that a vehicle has traced, thus avoiding excessive communication and data storage. Therefore, the better the correspondence between the traced track and the real track followed by the vehicle, the greater the added value offered by system applications. This enhancement to the representation of the track allows the creation of new applications in the realm of AVL systems, particularly for situations where accuracy plays an important role.展开更多
基金The Soft Science Research Project of Ministry of Housing and Urban-Rural Development of China (No. 2008-k5-14)
文摘In order to provide important parameters for schedule designing, decision-making bases for transit operation management and references for passengers traveling by bus, bus transit travel time reliability is analyzed and evaluated based on automatic vehicle location （AVL） data. Based on the statistical analysis of the bus transit travel time, six indices including the coefficient of variance, the width of travel time distribution, the mean commercial speed, the congestion frequency, the planning time index and the buffer time index are proposed. Moreover, a framework for evaluating bus transit travel time reliability is constructed. Finally, a case study on a certain bus route in Suzhou is conducted. Results show that the proposed evaluation index system is simple and intuitive, and it can effectively reflect the efficiency and stability of bus operations. And a distinguishing feature of bus transit travel time reliability is the temporal pattern. It varies across different time periods.
文摘A uniform optimization object function for front wheel orientation parameters of a vehicle is reported, which includes the tolerances of practical values and set values of front wheel orientation parameters under full load, and the changing value of each parameter with front wheel fluctuation to build a front suspension model for optimization analysis based on the multi-body dynamic (MD) theory. The original suspension is optimized with this model, and the variation law of each parameter with front wheel fluctuation is obtained. The results of a case study demonstrate that the front wheel orientation parameters of the optimized vehicle are reasonable under typical conditions and the variation of each parameter is in an ideal range with the wheel fluctuating within 40 mm. In addition, the driving performance is improved greatly in the road test and practical use.
文摘The development of GPS （global positioning system） receiver now can be integrated on a smartphone. GPS receiver on smartphones has been developed for location-based applications. Smartphones are very suitable to be used as an experimental tool, because smartphones are usually equipped with various types of sensors. This paper proposes a model observation vehicle speed on a road section based on the GPS data on the smartphone. Observations made by calculating the speed of the speed of vehicles moving through the data transfer at the GPS location of the smartphone, the data are then sent periodically to the server and server processing and storage of vehicle speed data. After tested with test reliability indicators use RMSE, observations with model observations speed, speed based on GPS data on a smartphone are relevant when compared with the speed directly from the vehicle＇s speedometer with the difference between the value of the difference of speed that is 3.1785 km/h.
文摘The use of AVL （automatic vehicle locator） systems has increased considerably. By using an AVL system, it is possible to know vehicle positions at the dispatch center, which allows the use of several applications, such as safety and security, logistics, and emergency response. High communication and data storage costs, however, lead to a low position update rate with the AVL products available, causing poor track representation, and making the route determined by the vehicle in urban areas almost illegible. This paper proposes a new approach by using intelligent techniques to choose the best position update moment to improve track representations. The principle underlying these techniques is based on vehicle status analysis （speed, direction and timing）, which tries to determine when a position update is required, in order to better represent the path that a vehicle has traced, thus avoiding excessive communication and data storage. Therefore, the better the correspondence between the traced track and the real track followed by the vehicle, the greater the added value offered by system applications. This enhancement to the representation of the track allows the creation of new applications in the realm of AVL systems, particularly for situations where accuracy plays an important role.
