冗余驱动盾构机推进系统机液耦合模型及载荷特性分析

针对某型盾构机推进系统分别建立了考虑冗余驱动的机械系统动力学模型和单组液压系统的简化液压模型,在此基础上建立了盾构机整个推进系统的机液耦合模型,给出基于外载-减压阀阀口开度关系的系统状态判定方法。在MATLAB/Simulink环境下进行数值建模与仿真,分析极端工况下各组推进缸的载荷特性。结果表明,该方法能够有效评价推进系统状态,并可为盾构机异质岩土掘进时驱动力分配的控制提供依据。

Public Attitudes Towards Policy Instruments for Congestion Mitigation in Shanghai

Congestion causes many externalities for the society, including time delays, excessive fuel consumption, air pollution, noise and safety concerns. In Shanghai, various policy options have been explored, piloted or applied; however, not all of them may be understood and accepted by the public. A survey was conducted to investigate people＇s attitudes towards several policy options. The main findings reveal that Shanghai residents are resistant to certain policies, such as congestion charges, higher parking charges in congested areas and car restrictions. Instead, they favor public transport provisions. The paper suggests that there is a case for promoting public transport and more efficient trips when the car ownership is still low, and for investing in a policy of educating the public on the ＇true＇ costs and causes of congestion before embarking on ,an intensive policy of congestion charges or restrictions.