路段人行横道二次过街感应式信号控制算法设计

在现有感应控制二次过街系统中,道路两边以及安全岛按钮控制多为分开控制,没有相互协调,行人在安全岛等待时间过长易导致违章过街等问题。在一次过街感应控制算法基础上,结合二次过街相关理论、机动车与行人延误机理以及行人过街信号配时理论,提出"人行绿波"协调思路,对路段二次过街感应控制算法进行设计,并应用Vissim软件进行仿真验证,结果显示设计感应控制算法能有效地降低行人和机动车延误。     

集装箱班轮公司航次运力销售过程优化模型

基于种群演变和共生理论,采用Cobb-Douglas生产函数描述航运市场整体需求,从顾客的购买行为出发,以收益最大作为集装箱班轮公司的经营目标,以基于时间序列的运力与运价作为决策变量,构建了集装箱班轮公司航次运力销售过程优化模型。运用Taylor公式与最小二乘法等代数变换手段将非线性规划问题转化为线性规划问题,对关键参数进行了标定与敏感性分析,并利用MATLAB软件进行仿真验证。仿真结果表明:当单个集装箱班轮公司的运力为104 TEU时,采用常规的销售策略,集装箱班轮公司可售出的运力为7 534~9 966TEU,获得收益为1 233 158~12 915 936USD,采用提出的优化模型,可售出的运力为9 915TEU,获得收益为15 111 975USD,收益至少提高17%;当2个集装箱班轮公司的运力均为104 TEU时,采用提出的优化模型,2个集装箱班轮公司可售出的运力分别为9 920、9 947TEU,获得收益分别为14 241 771、9 737 528USD,达到纳什均衡;当3个集装箱班轮公司的运力均为104 TEU时,采用提出的优化模型,3个集装箱班轮公司可售出的运力分别为8 289、5 526、6 034TEU,获得收益分别为6 755 755、6 119 906、4 377 758USD,达到纳什均衡。可见提出的模型可描述多个集装箱班轮公司运力销售情况,且表现出显著的优化效果。     

Investigation into the development of a bus electrical cooling fan system

Manufacturers of commercial vehicles are facing a substantial increase of heat release into their cooling systems. The main sources for this increase are more stringent emissions leading to new combustion technologies and the increased power of these engines. The total increase in the cooling requirement may be up to 20% over the current level. At the same time, the noise levels must be decreased, and fuel economy has to improve. This forces manufacturers to consider new concepts and optimize the efficiency of the cooling system. A bus engine cooling fan system is one of the main means of vehicular fuel efficiency reduction. This is becoming a major factor in city noise, and the necessity of electromagnetic technical development is very great. This study features a highly effective BLDC motor for engine cooling fans with high effectiveness and low noise, which is most suitable for fan blade technical development and cooling fan performance evaluation technical development.     

Requirement-based testing of an automotive ECU considering the behavior of the vehicle

HILS (Hardware In the Loop Simulation) and RBT (Requirement-Based Testing) are widely used to evaluate the performance and reliability of automotive ECUs (Electronic Control Units). The HILS method is used to predict the behavior of ECU-installed vehicles and to evaluate the performance of ECU controllers. RBT evaluates whether the embedded system satisfies the pre-defined requirements. In this study, the behavior of a vehicle is regarded as a system requirement, and an embedded system test procedure that evaluates the system requirement is proposed. In particular, a new method is introduced, which integrates HILS with RBT. Using the proposed method, the behavior of an articulated vehicle equipped with an AWS (All Wheel Steering) ECU is evaluated with RBT software.     

Application study on a control strategy for a hybrid electric public bus

This paper first describes the control strategy used in a hybrid electric public bus and then proposes a torque-balancing control strategy. Simulations were performed using the designed control strategies, and the results were analyzed under different conditions. The torque-balancing control strategy was improved on the basis of the efficiency-first ideas of the hybrid system. Finally, experiments were performed to verify that the efficiency-first and torque-balancing control strategy (EFCS) is both feasible and reliable. The simulation results showed that, compared with a conventional public bus, the hybrid electric bus could save approximately 27.3 percent on fuel consumption using the EFCS control strategy in a public bus in China, while under the Wuhan urban driving cycle.     

Torque control of engine clutch to improve the driving quality of hybrid electric vehicles

As a powertrain for hybrid electric vehicles (HEVs), the automatic transmission (AT) is not only convenient for the driver but also reduces hybridization costs because the existing production line is used to produce the AT. However, it has low fuel economy due to the torque converter. To overcome this disadvantage, this paper studies HEVs equipped an AT without a torque converter. In this case, additional torque control is needed to prevent the driving quality from deteriorating. This paper suggests three different torque control methods and develops a simulator for an HEV that can simulate the dynamic behaviors of the HEV when the engine clutch is engaged. The HEV drive train is modeled with AMESim, and a controller model is developed with MATLAB/Simulink. A co-simulation environment is established. By using the developed HEV simulator, simulations are conducted to analyze the dynamic behaviors of the HEV according to the control methods.     

Model development and experimental research on an air spring with auxiliary reservoir

This paper focuses on the dynamic stiffness and overall equivalent damping of an air spring connected to an orifice and an auxiliary reservoir, with respect to the displacement excitation frequency, orifice area, and auxiliary reservoir volume. A theoretical model of this air spring with its auxiliary reservoir is derived by utilizing the energy conservation equation, gas state equation, and orifice flow rate equation. Simulation results from the presented model reveal that, when the air spring is subject to harmonic displacement excitation, its dynamic stiffness increases with an increase in excitation frequency and decrease in orifice area. Smaller orifice areas and lower excitation frequencies result in higher overall equivalent damping. A validation experiment is also implemented. When compared with experimental results, simulations show consistent varying trends of the dynamic stiffness and overall equivalent damping. The model developed here can correctly describe the behavior of the air spring with auxiliary reservoir, indicating that it is reasonable and feasible.     

路难走还是走路难?

基于目前步行交通在国内城市面临的困境,首先从步行行为分析、影响因素以及步行速度、步行环境等方面阐述了对步行交通的基本认识.然后从城市规划与交通规划的角度,剖析了步行交通系统严重匮乏的表面症结与深层次问题,指出以往的城市与交通规划理念以及城市土地开发设计,严重破坏了城市原有机理与步行空间.最后强调在以人为本和节约资源的前...     

通过形状差异修正模式方法进行的损伤识别试验(英文)

An experimental program was undertaken to test the feasibility to detect the occurrence of structural damage using a modified mode shape difference technique. The vibration response of a steel beam fixed at one end and hinged at the other was obtained for the intact and damage conditions. Modal analysis was performed to extract the frequencies and mode shapes. The method shows a good potential in detection of occurrence and location of damage.