汽车排气系统用高性能钛合金的开发

近年来,钛及钛合金已被应用于发动机气门、汽车悬架弹簧、连杆及排气系统零部件,其应用范围呈增长趋势。研究了具有与工业用纯钛相同的冷加工性,并大幅提高了高温特性的钛合金。描述了新开发钛合金的设计理念及各项特性,对该合金的实用化现状等作了阐述。     

A Hemodynamic Study of the Effect of Neuromuscular Electrical Stimulation on Enhancing Popliteal Venous Flow

Neuromuscular electrical stimulation has been studied to be a method of prophylaxis for deep venous thrombosis by activating the calf muscle pump. However, there is little evidence of the effects of different stimulating parameters on hemodynamics and comfort levels. The objective of this paper is to compare the effects of different stimulating parameters(current amplitude, pulse-width) on hemodynamic alterations of the popliteal vein and the comfort levels in a group of fourteen healthy subjects. Doppler ultrasound detection of peak venous velocity and blood volume were taken from baseline, twelve sequential electrical stimulations and foot dorsiflexion for each subject. A visual analogue scale was used to assess the subjects' pain perception of neuromuscular electrical stimulation. The results showed that peak venous velocity and blood volume augmented as current amplitude and pulse-width increased while pain level also increased. A compromise was reached that parameters consisting of an amplitude of 10 m A and a pulse-width of 500 μs would obtain a high-peak venous velocity and blood flow volume with a relatively comfortable perception. In addition, parameters consisting of an amplitude of 20 m A and a pulse-width of 300 μs were also shown to be a promising choice. However, further studies need to be done to validate and enrich these findings.     

“三脚制动”判断液压制动系统常见故障

液压制动装置是以将踏板力转换成液压能的形式来传递制动力的,其传动机构简单,制动器产生的制动力矩与踏板力呈线性关系。若轮胎与路面的附着力足够,则汽车所受到的制动力也与踏板力呈线性关系。这项性能称为制动踏板感（俗称脚感）,驾驶员由此可以直接感受到汽车制动装置在各种工况下工作是否正常,并运用“三脚制动”（轻踏、快踏和连踏）,凭“脚感”来快速诊断故障。     

我所见到的美国高速公路系统及其机械化施工方法

凡是去过美国并有机会乘坐汽车进行州际旅行的人都会发现,美国高速公路系统规模之庞大,设施之完善,管理之有条不紊,给人留下的印象是很深刻的。我在美两年,曾乘车访问过东部、面部、北部等许多州的大城市,深深体会到,高速公     

大干、苦干,为加速我国铁路电气化而奋斗——全国电气化铁路工作会议首次在马角坝机务段胜利召开

在批修整风运动的推动下,交通部于六月四日至八日在成都铁路局马角坝机务段首次召开了全国电气化铁路工作会议。参加这次会议的有交通部和与电气化铁路有关的铁路局、分局及段的领导同志,有科研部门、机车制造厂的工程技术人员和战斗在电气化铁路第一线的工人。通过这次会议,为进一步加速我国电气化铁路的建设打下了良好基础。     

数字微波通信系统在京九铁路施工中的应用

介绍了京九铁路施工中采用的数字微波通信系统的概况，特殊功能的实现，实测主要指标和使用效果，投资情况，存在的主要问题。     

3种制动试验台比较与常见检测问题的分析

对我国目前机动车制动性能安全技术检验的3种试验台进行了比较，对滚筒制动试验台安全检测中出现的问题进行了分析，并就此提出了相应的解决办法。最后指出平板制动试验台是今后制动性能安全技术检验发展的方向。