Congestion tolling in the bottleneck model with heterogeneous values of time

When analysing the effects of transport policies it is important to adequately control for heterogeneity: previous studies note that ignoring heterogeneity biases the estimated welfare effects of tolling. This paper examines the effects of tolling, in a bottleneck model, with a continuously distributed value of time. With homogeneous users, first-best public tolling has no effect on prices. With heterogeneity it does: low values of time lose, and high values of time gain. The average congestion externality decreases with the heterogeneity in the value of time. Consequently, the welfare gain of first-best tolling also decreases. The more heterogeneous the value of time is, the lower the relative efficiency of a public pay-lane. This finding contrasts with the previous literature. Earlier studies, using static flow congestion, conclude that the relative efficiency increases with this type of heterogeneity. With more heterogeneity in the value of time, the relative efficiency of a private pay-lane is also lower, while that of a public time-invariant toll is higher. Our results suggest that the welfare gains of different tolling schemes are affected differently by heterogeneity. Further, the impact of heterogeneity on the effects of a policy also depends on the type of congestion considered.     

双向DC-DC变换器软开关技术研究

本文分析了移相全桥ZVS变换技术的工作原理,给出了谐振电感的选取条件,采用双向DC-DC变换的移相控制策略对设计电路进行了仿真,仿真结果验证了理论分析的正确性.     

The implications of MARPOL Annex V on the management of ports and coastal communities

Abstract

The passage of the Marine Plastics Pollution Research and Control Act of 1987 (MPPRCA), which codified Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL), has encompassed every commercial and recreational shipping and boating facility in the United States. As a group, these ports, harbors, and marinas form a significant, although proportionately small, portion of the coastline of the country. More important, the economic benefits derived from the complex shoreside infrastructures required for international ocean trade, commercial and recreational fishing, and pleasure boating indicate just how critical it is for these facilities to be in conformance with effective and prudent coastal zone and environmental management practices.     

基于卡尔曼滤波算法的电机转速精确估计

从无刷直流电机入手建立数学模型，利用卡尔曼Kalman（EKF）滤波原理算法，对无刷直流电机的转速进行精确估计，然后在Matlab环境下仿真，验证卡尔曼滤波算法对电机转速估计的精确性。     

地铁车辆辅助逆变电源分析研究

分析直接逆变方式、斩波降压逆变方式、两重斩波降压逆变方式地铁车辆辅助逆变电源的电路结构方案。结合北京"复八线"地铁车辆进口辅助逆变电源的技术条件,介绍DC750V国产化地铁车辆辅助逆变电源的研制方案和主要技术特点。给出方案的试验波形。     

阿斯顿马丁V12 Vantage RS

被无数人称作“花花公子之车”的阿斯顿马丁，尽管有失偏颇，但也从一个侧面说明了。只有极具品味的男人才配拥有它。它阿斯顿马丁V12 Vantage RS出现在我们面前时，赞美无需强迫……     

新型城市轨道车辆雨刮器的研制

利用微处理机控制技术的无刷直流电机,设计的"双机双臂"式新型雨刮器,可克服传统雨刮器的较大尺寸四连杆机构安装复杂、运行异响、高速时漂浮、归位不当、维护不便等缺点.     

具有宽电压调节范围的谐振型变流器

针对传统的变流器中输出电压一般总是低于交流输入电压的状况，提出了一种新型串联谐振直流环节变流器。该变流器在取消直流大电感，并为开关器件提供零电流开关条件的同时，还可以实现变流器输出电压在交流输入电压以上或以下的较宽范围内任意调节，而不受输入电压大小的限制。介绍了电路的工作原理，给出了升压及降压时两组有代表性的试验波形。     

基于Matlab／Simulink汽车驾驶员电动座椅控制系统的仿真设计

以汽车驾驶员电动座椅的水平调节为例,利用Matlab／Simuulink对具有自动调节功能的直流伺服位置控制系统的动态特性进行计算和仿真,从而确定该系统控制器的最佳控制参数的匹配。     

直流牵引系统保护试验原理和方法

介绍了电流上升率和电流增量2种保护的原理,以广州地铁一号线使用的3UB61保护装置为例,详细叙述了2种保护进行试验的原理和方法。实践证明,在对这2种保护的校验中,将原先的定性分析上升到定量分析的试验方法具有重要实际意义。