电力机车电度表分段计量计费系统

基于目前电力机车车载电量计量装置无法实现自动分段计量的现实。设计一种新型电力机车分段计量系统,以单片机为核心,在车载监控记录装置定位的基础上,将GPS和GSM技术相结合来实现提高列车的组合定位精度,从而比较准确地确定列车运行的位置,实现电量分区段计量,并通过GS M网络将列车运行状态数据实时发送到地面服务器。本系统把GPS模块、GSM模块以及单片机系统集成到一起,通过TAX箱转接出列车监控参数,综合分析三者定位数据,以实现最小误差融合算法,提高系统定位精度。该系统具有通用性,通过修改地图数据可适用于不同机车车型和不同运行线路,以实现电力机车电量全自动分段计量、记录、传输。     

进口淬火钢轨的性能及应用研究

针对20世纪90年代中期我国进口并铺设使用的日本、法国、奥地利及俄罗斯淬火钢轨,进行性能和应用状况分析,研究钢轨出现滚动接触疲劳缺陷的原因,提出解决措施。研究结果表明,日本、法国、奥地利的钢轨淬火工艺为离线欠速淬火工艺,仅对轨头进行加热和冷却处理,从而得到较高的强度和硬度。这种钢轨虽然在小半经曲线上表现出较高的抗磨耗性能,但在直线段上当通过总重达到4～5亿t.km时,钢轨踏面会出现隐伤、斜裂纹、剥离掉块等较严重的滚动接触疲劳缺陷;俄罗斯的钢轨淬火工艺为淬火+回火工艺,钢轨全断面经过加热和冷却处理,虽硬度和强度略低,但因其不同的廓面形状和较好的轮轨匹配关系,使得滚动接触疲劳伤损较轻;进口淬火钢轨出现的斜裂纹一般形成在轨距角处,与行车方向大致成40°～50°角并向行车方向发展。疲劳裂纹是由材料的棘齿形滞回效应引起的,并在高的接触应力下扩展。因此定期打磨钢轨和使用新廓面钢轨是解决滚动接触疲劳问题的有效方法。     

汽车发动机无分电器微机控制点火系统

无分电器微机控制点火系统是当今汽油机采用的一种先进点火装置，其特点是控制精度高，控制范围广，能适应发动机各种工况控制的需要。介绍了这种点火系统的基本结构和工作原理，并对其主要组成部件的特点和功能进行了论述。     

Estimating link travel time functions for heterogeneous traffic flows on freeways

Oversized vehicles, such as trucks, significantly contribute to traffic delays on freeways. Heterogeneous traffic populations, that is, those consisting of multiple vehicles types, can exhibit more complicated travel behaviors in the operating speed and performance, depending on the traffic volume as well as the proportions of vehicle types. In order to estimate the component travel time functions for heterogeneous traffic flows on a freeway, this study develops a microscopic traffic‐simulation based four‐step method. A piecewise continuous function is proposed for each vehicle type and its parameters are estimated using the traffic data generated by a microscopic traffic simulation model. The illustrated experiments based on VISSIM model indicate that (i) in addition to traffic volume, traffic composition has significant influence on the travel time of vehicles and (ii) the respective estimations for travel time of heterogeneous flows could greatly improve their estimation accuracy. Copyright © 2016 John Wiley & Sons, Ltd.     

Underwater digital terrain model with GPS-aided high-resolution profile-scan sonar images

The whole procedures of underwater digital terrain model (DTM) were presented by building with the global positioning system (GPS) aided high-resolution profile-scan sonar images. The algorithm regards the digital image scanned in a cycle as the raw data. First the label rings are detected with the improved Hough transform (HT) method and followed by curve-fitting for accurate location; then the most probable window for each ping is detected with weighted neighborhood gray-level co-occurrence matrix; and finally the DTM is built by integrating the GPS data with sonar data for 3D visualization. The case of an underwater trench for immersed tube road tunnel is illustrated.     

干线铁路沿线规划控制技术要求——以北京市为例

为实现干线铁路与沿线城市区域的协调发展,以北京市为例,分析干线铁路沿线规划的实施情况及面临的挑战,提出规划控制的原则与思路。综合国内外相关标准规范,提取干线铁路沿线规划控制应考虑的安全、噪声、振动、绿化、核磁辐射等因素及规划控制的指标要求。在此基础上,统筹铁路与城市发展需求,提出由干线铁路沿线隔离带和规划控制区,以及起始线、防护线和规划控制线组成的"两区三线"规划控制方法。阐述干线铁路沿线空间功能划分、城市分区、控制指标以及规划控制技术要求。最后,分析在规划控制方法影响下的用地敏感性并提出实施对策建议。     

柴油机径向式微粒捕集器过滤效率和压降特性的研究

根据泡沫陶瓷过滤体过滤孔道的特征,假设泡沫陶瓷过滤体由若干圆柱状纤维捕集单元组成,建立了捕集效率和压降的数学模型.利用该模型对某径向式微粒捕集器过滤体上微粒粒径分布、过滤效率和压降特性进行了预测.结果表明,该模型模拟结果与试验数据较好吻合.     

D30燃料在载货汽车上的应用研究

在SXQ4181G载货汽车上开展了燃用D30(二甲醚与柴油质量分数比3∶7)燃料的动力性、燃料经济性和排放特性的试验研究。针对D30燃料的特性,改造了原车燃料供给系统和优化了喷油泵及喷油器参数后,进行了发动机台架试验和整车道路试验。结果表明,燃用D30燃料的动力性与原柴油机相当,经热值修正后的当量燃料消耗率有所改善;NOx排放下降(低转速时尤其明显);HC排放有所降低,CO排放没有明显变化,烟度在全转速范围内大幅度下降。     

侧向排烟城市道路隧道的水幕阻烟隔热性能研究

为探究侧向排烟城市道路隧道的水幕阻烟隔热作用,并为隧道的水幕设计和消防疏散提供参考,使用FDS软件对水幕模型进行数值模拟计算。在8 MW的火灾规模下,研究隧道顶部2个喷头和4个喷头2种布置方式,0.08、0.1、0.25、0.4 MPa 4种水喷头工作压力、侧向排烟量大小、排烟口间距和数量等主要因素对隧道水幕阻烟隔热性能的影响,分析比较烟气扩散范围、温度及能见度的变化规律,评估隧道疏散救援环境。结果表明： 水幕系统能抑制隧道内烟气的扩散,阻止隧道温度过快上涨,并能改善隧道内的能见度; 水幕系统在排烟量增加、排烟口间距减小、排烟口数量增加的情况下,阻烟隔热性能更明显; 水幕系统对隧道内能见度的改善作用只维持于火灾发生的前中期,后期效果将减弱,因此消防救援工作应在火灾发生的前中期开展。     

Examining the theoretical–empirical inconsistency on stationarity of shipping freight rate

As market price, shipping freight rates should in theory be stationary, but most empirical tests have found them to be non-stationary. To examine the causes of this theoretical–empirical inconsistency, we investigate the sensitivities of the stationarity of shipping freight rates from two perspectives: sample length and sample window. Longer samples are found not sufficient to make them stationary. Instead, sample windows separated by structural breaks are tested as stationary. Moreover, freight rates are found to have entered into a new phase since the 2008 financial crisis. This study contributes to the literature on the stationarity of shipping freight rates by providing an explanation for the theoretical–empirical inconsistency.