Timing rules for major transportation investments

The timing decision for major transportation investments – when to build – typically is made without an objective approach for considering the economic value of implementation at different times. This paper uses a model of benefit-cost analysis and derives rules for timing major transportation investments. Three sets of conditions are considered, depending on whether annual benefits of an investment are uncertain and whether the objective is to maximize net present value or simply to achieve positive net present value. The timing rules under each set of conditions are stated in three forms: benefit-cost ratio, annual benefits, and implementation time. The paper compares these timing rules analytically, discusses potential applications, and illustrates them with a numerical example. Consequences of incorrectly using the timing rules are also examined with the example. This revised version was published online in June 2006 with corrections to the Cover Date.     

教育部基金管理信息系统的设计与开发

作者介绍了教育部基金管理信息系统的研究与设计方法,阐述了系统的功能和特点,探讨了数据兼容,对时间的处理以及报表打印的关键技术问题.并针对该系统最关键的评审部分提出了进一步的设想,既用基于WEB的知识挖掘的思想,知识挖掘与网络技术相结合来选择各学科领域的专家建立评审专家库     

Dynamic Interaction of Railway Train and Bridges

An analytical method for obtaining the dymanic responses of a train of locomotives moving on bridges is presented. The ratio of dynamic response to maximum static response is called the amplification factor, and its maximum absolute value minus one is called the impact. Each four-axle locomotive is modelled as a rigid body with three degrees of freedom: bounce, pitch and roll, and with a suspension system consisting of springs mounted on wheels. The locomotives are assumed to be connected by frictionless joints to form the train. The bridge is modelled as a three dimensional structure, with the masses lumped at the truss joints. All joints, including the floor beam connections, are assumed to be rigid, except those for the bracing members, which are assumed to be hinged. Vertical displacements are considered as the only dynamic degree of freedom. The mathematical formulation is described briefly, and a numerical example is given. Locomotive and truss member properties, together with stresses in some typical members, are given in the tables. The amplification factors of the responses in some typical bridge members are shown in the figures.     

洪泽湖蒋坝水位站迁址重建的分析与设计

蒋坝水位站是洪泽湖代表水位之一,是淮河流域防汛抗旱调度的重要依据。建于1914年1月,2004年4月迁址重建。分析了蒋坝水位站的代表性;介绍了站址方案的选择和水位观测平台高程的确定。叙述了水位观测平台的结构型式和结构设计,以及施工情况。通过一年的比测,新建的蒋坝水位站达到了设计目的,在2007年淮河大水中发挥了重要作用。     

LTW495C电台问题的解决

LTW495C型电台是无线列调运用的主要设备。该机有时发生“死机”现象，使部分或全部功能丢失，造成通信中断。     

DETECTION OF HPV 16 E_6G ENE IN CERVICAL CANCER TISSUE

ＤＥＴＥＣＴＩＯＮＯＦＨＰＶ１６Ｅ_６ＧＥＮＥＩＮＣＥＲＶＩＣＡＬＣＡＮＣＥＲＴＩＳＳＵＥ￥ＹｕａｎＹｕｈａｎｇ（袁育康）；ＬｉｕＨａｎｘｉｎ（刘汉馨）；ＬｉｕＺｂｅｎｇｒｅｎｇ（刘正风）；ＣｈｕＹｏｎｇｌｉｅ（楚雍烈）（ＤｅｐａｒｔｍｅｎｔｏｆＭｉ?..     

改进重力模型在铁路客运量预测中的应用

对重力模型参数随时间变化的规律进行了研究,用正弦函数描述了重力模型参数的波动规律,改进了原有重力模型将参数标定为常数的缺陷,并通过数据拟合对实例进行了验证,结果表明该模型预测精度较高。     

在线车辆远程监测信号的采集及处理

利用现有GSM移动通信网设计了在线车辆远程监测总体方案，并搭建试验室研究平台分析信号远程传输特性，同时进行了汽车发动机状态信号的远程采集。以所定义的频域修正因子，对远程采集信号进行了有效的修正。研究结果开拓了在线车辆远程监测系统的研究范围。     

ZnOw改善橡胶和轮胎耐磨性能的研究

研究了ZnOw／NR—SBR—BR复合材料的耐磨性能，发现经偶联剂表面处理的ZnOw对提高橡胶材料的耐磨性能有良好的效果。在轮胎胎面胶中加入3份标准配方的氧化锌晶须对轮胎进行改性，结果表明，氧化锌晶须不仅可以改善橡胶和轮胎的耐磨性能，而且可以提高轮胎的高速安全性和耐久性。对复合材料受磨表面和截面的微观形貌进行了研究，分析了氧化锌晶须提高橡胶复合材料耐磨性能的机理，并提出可以用橡胶材料表面分形维数值的大小来判断磨损程度。     

满足国Ⅲ排放标准的摩托车催化剂涂层研究

利用耐久性涂层制备的涂层1号催化剂，在新鲜态及老化态时，对CO、HC、NQ的转化率都优于涂层2号催化剂，特别是老化态催化剂涂层1号的催化转化率分别比涂层2号催化剂高16．8％、8．6％及30％。空燃比对催化剂的转化效率具有很大影响，精确控制的空燃比状况能提高催化剂的转化效率，从而降低催化剂的使用成本。