紧抓历史机遇夯实发展基础为实现中铁物资战略目标开好头起好步

1 在复杂多变的经济环境中顽强拼搏,2008年各项工作取得了新的成绩 1.1 生产经营继续较快发展,取得了良好业绩 全年实现营业收入1002亿元,历史性地迈上了千亿元的大台阶,比上年增长26.8%.完成了国资委经营业绩考核指标.     

浅谈二手车及其鉴定评估方法

中国是世界上汽车产销量最大的国家,随着汽车存有量不断攀升、汽车消费文化的提升,汽车消费环境的不断优化,二手车的消费将会成为汽车消费的重要支撑,而在二手车消费的过程中,就需要对二手车的价值进行科学有效的评估。     

Flow-field guided steering control for rigid autonomous ground vehicles in low-speed manoeuvring

ABSTRACT

This paper studies the low-speed manoeuvring problem for autono-mous ground vehicles operating in complex static environments. Making use of the intrinsic property of a fluid to naturally find its way to an outflow destination, a novel guidance method is proposed. In this approach, a reference flow field is calculated numerically through Computational Fluid Dynamics, based on which both the reference path topology and the steering reference to achieve the path are derived in a single process. Steering control considers three constraints: obstacle and boundary avoidance, rigidity of the vehicle, plus the non-holonomic velocity constraints due to the steering system. The influences of the parameters used during the flow field simulation and the control algorithm are discussed through numerical cases. A divergency field is defined to evaluate the quality of the flow field in guiding the vehicle. This is used to identify any problematic branching features of the flow, and control is adapted in the neighbourhood of such branching features to resolve possible ambiguities in the control reference. Results demonstrate the effectiveness of the method in finding smooth and feasible motion paths, even in complex environments.     

Global supply chain and port/terminal: integration and competitiveness

Much has been said of the importance of port and terminal integration in the supply chain. Authors have stressed the importance of agility to the port environment, which involves being proactive along supply chains, facilitation of intermodal integration, as well as organizational integration and partnership between ports and users. Despite the well articulated importance of the issues, little has been offered in terms of conceptualizations and empirical evidence of what really is meant by port/terminal integration in the supply chain, how such integration can be measured and quantified as well as the extent to which different ports/terminals in the world are integrated in the supply chain and competitive performance implications arising thereof. This paper aims to make a contribution in this respect by (i) reviewing the relevant literature on supply chain integration and port integration in the supply chain, (ii) conceptualizing measures for port/terminal integration in the supply chain, (iii) empirically testing the influence of port/terminal integration in the supply chain on port competitiveness and (iv) outlining the significance and value of the study for port operators, shipping lines, transport providers and for further research.     

舵柄与舵杆无键液压套合连接推入量计算

介绍了舵柄与舵杆无键液压套合工艺的优点。对这种工艺的工作原理、受力计算及液压套合推入量计算作了分析并探讨其实用的计算方法和计算公式。     

Experimental study on a model azimuthing podded propulsor in ice

The objective of this study was to investigate the performance of a model azimuthing podded propulsor in ice-covered water. Model tests were carried out with two different depths of cut into the ice (15 and 35 mm), two different ice conditions (presawn and pack ice conditions), and four different azimuthing angles. The depth of cut is the maximum penetration depth of the propeller blade into the ice block. The 0.3-m-diameter model propeller was operated in a continuous ice milling condition. Ice loads were measured by several sensors which were installed in various positions on the model. Six one-axis pancake-style load cells on the top of the model measured the global loads and two six-component dynamometers were installed on the shaft to measure the shaft loads. One six-component dynamometer was attached to the one of the propeller blades inside the hub to measure the blade loads. The pod unit and propeller performance in ice are presented. Ice-related loads, which were obtained when the blade was inside the ice block, are introduced and discussed. During the propeller–ice interaction, a blade can experience the path generated by the previous blade, which is called the shadowing effect. The effects of shadowing, depth of cut, azimuthing angle, and advance coefficient on propulsor performance are presented and discussed.     

Link-16(JTIDS终端)的TDMA体系结构分析

分析Link-16(JTIDS终端)的时隙划分、脉冲传输特点,着重研究舰载和机载Link-16的数据、语音时隙分配结构,就TDMA网络体系的通信模式、类型以及组网方式进行总结并给出常用网络参与组(NPG)的任务功能.     

船舶电站柴油发电机组混合H_2/H_∞调速器的研究

将混合H2/H∞控制理论应用于柴油机调速系统的设计,将柴油机调速系统的性能要求转化为标准混合H2/H∞控制问题.计算机仿真结果表明,利用线性矩阵不等式方法所设计的混合H2/H∞调速器能在考虑模型不确定性的情况下,有效提高系统的动态精确度和抑制扰动的能力,改善船舶电力系统频率的稳定性.     

浅谈新双积分法规下乘用车降油耗方案研究

乘用车燃油经济性是评价车辆性能的重要指标,通常以在一定循环行驶试验工况下,行驶100km所消耗燃油升数(单位为L/100km)作为评价指标。影响乘用车燃油经济性的因素很多,文章以公司某在研SUV为例,通过仿真及转鼓油耗测试手段,在保证车辆驾驶体验体验前提下,研究如何降低整车燃油经济性。