基于自由空间光的可调谐DPSK信号解调器

提出了一种基于自由空间差分延时干涉的可快速调谐的DPSK信号解调器.实现了10Gb/s以及40 Gb/s NRZ-DPSK信号的解调,误码率小于10-9.实验结果证明该解调器适用于10Gb/s及更高比特速率NRZ-DPSK信号的解调,调谐时间可达μs,调谐范围从2.5 Gb/s到40 Gb/s.与波导型马赫-曾德尔型差分延迟干涉解调器相比,能实现快速调谐,可用于克服因信号抖动导致的时钟失步等问题.     

A conceptual framework for cooperation in hinterland development between neighbouring seaport authorities

The hinterland of a port is probably the most important aspect in the competition between gateway ports. This paper, starting with a literature overview, shows how the port authority can extend its hinterland with the aim of increasing its attractiveness and, eventually, its throughput. To achieve this, it can be advantageous to cooperate with adjacent port authorities. Together, through cooperation, economies of scale can be realised that facilitate a modal shift away from road to a more efficient and more sustainable transport. This would reduce the cost of transport to/from the hinterland region from/to these ports consequently increasing the attractiveness and the market share of the cooperating ports for this region. The paper describes a conceptual method to identify and quantify the opportunities for cooperation in the hinterland. The framework starts, after some basic transport economic concepts, from (theoretically available) hinterland data to locate regions that are at the edge of the contested hinterland of a port region and results in a methodology that can be used to generate a quantified list of regions where cooperation will make a difference. Using this methodology, port authorities (PAs), of any region where hinterland data are available, can list, together with their neighbours, the regions where to prioritise their efforts.     

Estimating heterogeneity of car travelers on mode shifting behavior based on discrete choice models

In order to understand the mode shift behavior of car travelers and relieve traffic congestion, a Stated Preference survey has been conducted in the city of Ji'nan in China to analyze bus choice behavior and the heterogeneity of car travelers. Several discrete choice models, including multinomial logit, mixed logit and latent class model (LCM) are developed based on these survey data. A comparative analysis indicates that the LCM has the highest precision and is more suitable to analyze the heterogeneity of car travelers. The LCM divides car travelers into three classes. Different classes have different sets of influencing factors in the model. Policy recommendations are also proposed for those classes to promote bus shift from car travelers based on the model results. Finally, sensitivity analysis on parking fees and fuel cost is carried out on the LCMs under different bus service levels. Car travelers have different sensitivities to the influencing factors. The conclusions indicate that the LCM can reflect the heterogeneity and preferences of car travelers and can be used to understand how to shift the behavior of car travelers and make more effective traffic policy.     

广州地铁车站自动排班系统

为了提高地铁车站排班效率和排班质量,广州地铁公司研发了车务信息管理平台(TNS),实现地铁车站通过计算机自动排班。文章介绍广州地铁车站自动排班系统架构、自动排班原则和系统实现形式。     

基于模糊故障树的列控风险发生频率研究

引入模糊数,采用基于模糊故障树的计算方法对列控风险发生频率等级进行计算。该方法首先采用故障树对需要进行发生频率等级评估的列控风险进行描述,对于有统计数据信息的基本事件的发生频率采用精确值表示,对于没有统计数据信息的基本事件的发生频率采用模糊数表示;之后采用模糊算子对顶事件的发生频率进行计算,得到顶事件的模糊数;然后采用重心法对顶事件的模糊数进行去模糊化,得到顶事件的发生频率精确值;最后依据风险发生频率等级表确定风险的发生频率等级。以道岔中风险为例进行计算,计算结果验证了基于模糊故障树计算方法的有效性。     

Inland transportation system planning by life-cycle impact assessment: a case study. 2nd report: single comparison index

A model to estimate and compare the ecological impact and economic feasibility of a land transportation system (trucks) and a marine transportation system (cargo ships) was developed and presented in a previous report.¹ Three different comparison indices—environmental, economic, and customer service—were used to evaluate and compare their ecological impacts and determine their economic superiority. In this article, a single comparison index is proposed and assessed for the two transportation systems. The estimates were made for nine different routes in Japan. A simple mathematical model of the whole methodology is given. The sensitivity of the weighting factors used in the comparison method was analyzed. The social cost saving in monetary terms through a modal shift is also presented. Received: February 15, 2001 / Accepted: September 19, 2001     

船舶动力装置双层隔振系统的优化设计

中间筏体为弹性体的双层隔振技术（浮筏）,已经大量地应用在船舶动力装置的减振降噪中。本文首先指出了振级级落差可以用频响函数来表达,从而进一步讨论了以振级差为目标的优化方法,该优化方法的核心是频响函数的灵敏度。给出的实例表明,该优化方法很有发展潜力。     

BP神经网络在健康监测基准模型损伤识别中的应用

本文针对ASCE提出的健康监测基准问题的结构模型,分析了基于固有频率的结构损伤识别方法,使用MATLAB软件模拟不同的结构损伤情况,根据得到的固有频率构造BP神经网络输入参数并进行相应的训练,通过神经网络对结构损伤分步分层次的进行诊断。通过数值分析结果说明这种方法可以取得较好结果,也进一步说明神经网络技术是进行结构损伤识别有效方法。     

汽车自动变速分层协调换挡控制

将汽车自动变速控制策略分成上层与下层两部分,进行自动变速分层协调控制。下层为最佳动力性和最佳经济性的基本换挡控制,上层决策层对识别的驾驶意图、车辆工况和道路环境信息进行占优分析和优先级设定,决策出车辆当前状态下性能最优的控制目标,并对下层基本换挡控制策略进行修正和调整。分析结果表明:采用分层协调控制策略的车辆在爬坡和过弯道工况时比独立控制换挡次数分别减少了4次和2次,在变速箱油温升高时比独立控制能及时降低挡位,低附着路面起步时挡位比独立控制高。采用分层协调控制策略可有效降低跳挡频率,减小换挡部件磨损,提高车辆通过性、行驶平顺性和安全性。     

基于深度分层图的虚拟视点合成方法的研究

提出了一种基于深度图分层的虚拟视点合成算法,该方法先采用均值漂移聚类算法将深度图进行分割处理,使得深度图中的对象块有同一深度值,然后对视频信息以及处理后的深度信息进行3D图像转换,再对图像中的空洞进行填充处理,完成了虚拟视点合成。实验结果表明,与通过MVC编码后合成的虚拟视点相比,该方案改进了合成图中对象边缘的质量问题。