机车车辆动力学试验线况识别的方法

在机车车辆动力学性能试验中 ,必须考察评价被试车在各种不同的速度、线况下的动力学性能 ,为此在动力学试验中必须采集线路状况。对目前采用的各种线况采集方法进行了分析比较 ,指出了它们的优缺点 ,并对它们的使用范围提出了建议     

Wave climate evolution in the Bay of Biscay over two decades

As a background, a review of long term evolution of wave climate in the North Atlantic is discussed. Most studies show that interannual evolutions in wave heights may be related to climatic factors, such as the North Atlantic Oscillation Index for example.Data of a waverider, consisting of a time series of 20 years in the Bay of Biscay (off Biscarosse, France), are analysed. Based on these data obtained from 1980, wave heights tend to decrease over the period. Also, interannual evolutions exist, particularly in the wave period. The fact that the annual wave periods at Biscarosse are found to vary more significantly than the annual wave heights led us to assume that it is an indirect effect of the evolution in the location of generating storms relative to the buoy. The relationships between wave parameters and climatic factors such as the North Atlantic Oscillation Index and the Garonne discharge have been derived: they show that the NAO index is negatively correlated with the river discharge and positively correlated with the wave period. This result is in agreement with the general climate scheme associated with NAO cycle proposed by Kushnir et al. [Kushnir, Y., Cardone, V.J., Cane, M., 1995. Link between Atlantic climate variability of surface wave height and sea level pressure. Proc. Fourth Int. Workshop on Wave Incasting and forecasting, Banff, AB, Canada, 59–64.]: NAO+ shifts storm tracks northward and dry weather are encountered in the southern part of Europe (conversely NAO− brings storm tracks and rainfall closer). Concerning wave heights, the lack of dependence on NAO index may be associated with compensation effects between wind intensity and storm tracks: wave energy is partly dissipated while reaching the Bay of Biscay in case of severe but distant storms (NAO+), which is not the case for storms generated nearer to the buoy and associated with moderate westerly winds (NOA−). However, the reason of the decrease in wave heights is not clear.     

改进的灰色模型在港口吞吐量预测中的应用

用提高原始数据列光滑度的方法来提高灰色预测模型(GM模型)的精度。利用函数a-xm(a>1,m>1)对原始离散数据列｛x(0)(k)｝进行变换,原始数据列变成a-[x(0)(k)]m ,很大程度上提高了预测精度。将这种方法应用于港口吞吐量的预测,结果比传统灰色预测方法精度高很多,对正确做出港口发展战略、统筹安排、正确决策以及减少损失有重大意义。     

智能型列车总线ARCNET通信网卡的研究

分析了ＡＲＣＮＥＴ网络协议及其特点，介绍了列车总线智能型ＡＲＣＮＥＴ通信网卡的硬件设计，给出了网卡的通信软件流程图。试验结果表明：该网卡能够减少主机的开销，并具有实时性好、可靠性高等优点。     

新型多模式高速无线多媒体数传技术的研究

为解决铁路高速无线数传的安全与可靠性,研制和试用对数据、话音、图像多业务信息适配、汇接与同传的软硬平台。采用非线性码MM高密度密钥,实现"加密与纠错兼容一体化",达到破译复杂度为O(2104),纠错能力为检4纠3,正确解密概率达0 999999988,数据信息传输速率高达3Mbps～22Mbps时传输误码率优于10-10,重传率为0。为实现多模式无线数传,研制出多速率、多路、多媒体复用器,具有低速异步及高、低速同步与多速率数传功能,同步时间小于1s,开机同步可靠率达99%,设有动态图像、数据、话音、文本等四路通道,具有自适应多模式信息组合数据通道,使数字系统可实现同一平台多作业信息复用传输。数传网络接口可支持OS/2与Windows两种操作系统相互平滑转换,开发出多点互联控制软件,实现局部网随机接入。设计出"线状"、"链状"、"面状"、"点 面混合"及"树状"五种信息网型,满足铁路运输信息化及应用多媒体数据2km～120km的传输需求。     

内河智能交通系统研究

内河航运在运输成本、环保、可持续发展等方面优势突出,而内河航运管理相对滞后。提出内河智能交通系统的概念,阐明内河智能交通系统的3个关键技术:船舶定位、无线数据通信、电子河图显示与信息系统,并对我国发展内河智能交通系统提出建议。     

USB点对点通信技术在机车数据转储中的应用

介绍了基于单片机控制的USB数据转储器的工作原理,重点阐述了USB接口部分电路设计及软件设计。在DF4D型机车上的运用表明,系统设计合理,运行可靠,能满足现场大量数据快速转储的需要。     

GML3.0及其在空间数据建模中的研究

GML的提出为解决空间数据共享提供了一个契机。地理标记语言GML(Geography Markup language)是由OGC开发的一套基于XML的数据编码规则,主要用于地理信息的建模、存储和传输。本文首先简要介绍了GML3．0新增的内容、功能以及基本的数据模型。然后以构建旅游地理信息系统的空间模型为例,论述了GML空间数据建模的步骤。     

Determinants of modal choice in freight transport

In the next few years, exciting developments in the field of freight transport are likely to occur. The Channel Tunnel will be perceived as giving railways much greater distance of operation, compared to the current train ferry to/from Great Britain. The further development of swap-body technology will allow easier modal transfer and the creation, in 1992, of a single market in Europe will transform the pattern of trade. All of these are likely to have significant impacts on modal choice, and hence modal split, in freight transport. Reappraisal by many firms of the modes of transport used is likely but will it result in a net transfer of freight from road to rail and, if so, to what extent? To answer such questions, an accurate and reliable method of predicting modal split is required. Research in the past has concentrated on the development of modal split models based on generalised costs. These fail to explain adequately the prevalence of road freight in the UK. From surveys of freight managers within industry, it is clear that models to date rely too heavily on the economic cost factor and too little on behavioural factors (Jeffs 1985). This paper derives from a recent study of freight transport modal choice from the standpoint of the transport decision-maker within the firm. It attempts to shed light on the actual parameters which should be incorporated into a modal split model. Many variables appear to exert an influence on modal choice decision-making process. However, it is possible to categorise them into six main groups, namely: customer-requirements; product-characteristics; company structure/organisation; government interventions; available transport facilities; and perceptions of the decision-maker him/herself. It is the interactions and inter-relationships between these which ultimately determine freight modal split. This study has shown that the relationship between the outcome of the transport decision process and the values of particular determinants of modal split is not straight-forward, due to the complexity and variety of interactions involved. Perhaps one of the main reasons for researchers' failure hitherto to develop a successful modal-split model has been the preoccupation with techniques that rely on the development of common metric (e.g. generalised cost), which has led to the exclusion of some important explanatory variables along quite different dimensions. Another important issue concerns the appropriate level of aggregation. In order not to reduce the explanatory power of the key variables, it is important to work at a disaggregate level, although this does make substantial demands on data. The use of factor analysis enables both the aggregation of information without loss of behavioural reality and the specification of variables in terms of a common metric. In conclusion, freight transport has usually been examined within too narrow a framework. It must be placed firmly within the context of the total industrial process. The demand for freight transport is directly influenced by the level, composition and geographical distribution of production and consumption activities. Freight flows are complex and so it is highly unlikely that a universal mode-choice model can ever be developed. Future research should, therefore, be directed towards developing partial models in response to specific needs of those involved in decision-taking in the freight sector.     

GPRS在工业监控中的应用

基于移动通信和Internet的蓬勃发展，使用了GPRS和Internet技术以实现工业监控系统的广域信息智能化。GPRS技术提高了工业监控系统的开放性、可视性、分散性、移动性、数据／图像高速传输，以及铁路专用网、无线通信网络和Internet之间的互联互通等，本文在对GPRS进行介绍的同时，讨论了其在工业监控中的应用前景以及具体的实现方案。实验结果显示，本方案切实可行。