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991.
高速铁路常用供电方式接地回流研究 总被引:1,自引:0,他引:1
分析了在高速铁路常用的供电方式下,即带回流线的直接供电方式和AT供电方式下的接地回流情况,通过对2种供电方式下牵引网的等效电路建模、计算,得到钢轨电流和地中电流分布系数的近似计算公式,并对回流情况进行了分析。 相似文献
992.
Phase change analysis of an underwater glider propelled by the ocean's thermal energy 总被引:1,自引:0,他引:1
KONG Qiao-ling MA Jie 《船舶与海洋工程学报》2007,6(4):37-43
The phase change characteristic of the power source of an underwater glider propelled by the ocean's thermal energy is the key factor in glider attitude control. A numerical model has been established based on the enthalpy method to analyze the phase change heat transfer process under convective boundary conditions. Phase change is not an isothermal process, but one that occurs at a range of temperature. The total melting time of the material is very sensitive to the surrounding temperature. When the temperature of the surroundings decreases 8 degrees, the total melting time increases 1.8 times. But variations in surrounding temperature have little effect on the initial temperature of phase change, and the slope of the temperature time history curve remains the same. However, the temperature at which phase change is completed decreases significantly. Our research shows that the phase change process is also affected by container size, boundary conditions, and the power source's cross sectional area. Materials stored in 3 cylindrical containers with a diameter of 38ram needed the shortest phase change time. Our conclusions should be helpful in effective design of underwater glider power systems. 相似文献
993.
数据挖掘技术在经济中的应用是信息决策、经济管理等领域的前沿研究方向之一。企业决策离不开销售预测,传统的预测系统已远远不能满足要求。针对传统预测系统存在的问题,本文简要概述了数据挖掘的基本理论和方法,介绍了数据挖掘在企业中的重要性和基本步骤,并设计了面向销售预测的数据挖掘一般结构框架。 相似文献
994.
简要介绍离子化检测技术的发展过程和装备情况,重点介绍了代表当前离子化技术水平的闭合漂移管IMS技术原理、特点和发展趋势。 相似文献
995.
996.
Proshanto K. Mukherjee 《WMU Journal of Maritime Affairs》2007,6(2):147-166
Within the comprehensive body of law encompassed by the International Convention on Safety of Life at Sea, 1974 (SOLAS), there
are two regimes that are topical and outstanding in the current maritime milieu. These are the international safety management
and the international ship and port facility regimes, both characterized by two codes serving as the centre of gravity of
each, namely, the ISM Code and the ISPS Code, respectively. In this article the concept of the code as a legal instrument
is perused following which a critical legal analysis is carried out of the two above-mentioned Codes, including their backgrounds,
the evolutionary process culminating into the regimes and their interrelationships. Several anomalies and inadequacies in
the two regimes are identified but in the final analysis it is concluded that both instruments are salutary additions to the
body of convention law generated by the International Maritime Organization (IMO). They will undoubtedly influence the continuing
development of international law in the field of maritime safety and security. 相似文献
997.
998.
沈阳市是我国东北地区中心城市.其城市快速轨道交通近期规划5条线182km.远期规划11条线400km。目前开工建设的沈阳市地铁1号线一期工程是沈阳市地铁1号线工程城区段.线路西起沈阳经济技术开发区张士站.沿开发大道(沧海路)向北过沈新路,沿太湖街北行.然后右转沿沈大路、建设大路走行,过铁西广场后转向云蜂北街、 相似文献
999.
Junbo Jia 《Journal of Marine Science and Technology》2007,12(1):43-57
To reduce the area on deck occupied by each car and the labour and time required for lashing and unlashing cars, it has been
proposed by the author that in some conditions, cars on decks could be transported without lashing. To evaluate cargo securing
based on this “lashing-free” concept, computational code was developed to calculate the vehicle–deck interactions for various
ship motions. The code was structured by incorporating a vehicle model into a piece of ship motion calculation code. A series
of time-domain simulations were conducted to evaluate vehicle securing. It was found that for a target ship consisting of
a 6000-unit Ro-Ro vessel, vehicle securing is mainly influenced by the ship's rolling motions and is highly dependent on the
wave height and loading conditions. It was suggested from the analysis that vehicles could be secured without being lashed
in a large area of the ship in specific weather conditions and on some routes with less adverse sea states. However, it is
still suggested that conventional lashing holes should be constructed on the deck because in severe sea states the cars will
still need to be lashed. The limitations of the current investigations are also presented.
The relevant research work was carried out at the Division of Ship Design and Engineering, Department of Shipping and Marine
Technology, Chalmers University of Technology. 相似文献
1000.
1问题的提出啃轨是门吊使用中常见故障,主要由于门吊在运行中车轮偏斜运行,车轮边缘与走行钢轨之间产生严重摩擦。我公司大部分货场都使用20T门吊,由于架设比较早,使用时间较长,在运行过程中多台门吊出现大小车不同程度的啃轨现象,车轮边缘和钢轨间严重磨损,这些导致小车运行机构的运行阻力增大、电动机功率额外损耗、传动部件受力增加,时间长将导致车轮磨损超限报废,如果不及时进行更换,严重的将危及安全,影 相似文献