基于灰色小波神经网络的船舶交通流预测研究

船舶交通流预测的准确性和可靠性已成为制约港口经济科学发展的瓶颈因素。文章综合利用小波变换的局部化性质与神经网络的自学习能力,并引入灰色模型以反映船舶交通流的发展趋势,使得小波神经网络在灰色模型预测结果的基础上结合船舶交通流的影响因素再预测,构成基于灰色小波神经网络的船舶交通流组合预测模型。实验结果表明,灰色小波神经网络的预测精度高于BP神经网络与小波神经网络,提高了整个预测系统的精度及其鲁棒性。     

H∞ Robust Fault-Tolerant Controller Design for an Autonomous Underwater Vehicle＇s Navigation Control System

In order to improve the security and reliability for autonomous underwater vehicle (AUV) navigation, an H_∞ robust fault-tolerant controller was designed after analyzing variations in state-feedback gain. Operating conditions and the design method were then analyzed so that the control problem could be expressed as a mathematical optimization problem. This permitted the use of linear matrix inequalities (LMI) to solve for the H_∞ controller for the system. When considering different actuator failures, these conditions were then also mathematically expressed, allowing the H_∞ robust controller to solve for these events and thus be fault-tolerant. Finally, simulation results showed that the H_∞ robust fault-tolerant controller could provide precise AUV navigation control with strong robustness.     

船用柴油机排气后处理技术进展

随着航运业的不断发展,船用柴油机排放污染物也已成为日趋严重的污染源。本文综述了船用柴油机排气中NOx、SOx．颗粒物、HC和COx等的后处理方法和技术,重点介绍NOx和SOx的净化技术．最后展望了船用柴油机排气控制技术的发展方向。     

城市轨道交通钢轨伤损分析

随着上海市轨道交通运营年限的不断增加,钢轨伤损已经成为影响线路安全性的一个重要因素.根据上海轨道交通1号线的钢轨损伤情况,对引起钢轨伤损的原因和伤损的数量进行统计分析.结果发现:上行和下行线路的伤损种类与分布大致相同;引起钢轨伤损的三个主要原因分别是焊接、轮轨作用以及钢轨的材质;钢轨裂纹主要发生在曲线地段.针对性地提出了关于减轻钢轨伤损的对策措施.     

养护方式对宁波通途路综合管廊混凝土抗裂性能的影响

为提高综合管廊混凝土的抗裂性能,开展椭圆环法及实体模型试验,对胶砂或混凝土初始开裂时间、裂缝宽度、总开裂面积进行统计与分析,以研究减缩剂养护、混凝土养护剂养护和土工布养护3种养护方式对综合管廊混凝土抗裂性能的影响。由试验结果得出： 1）减缩剂养护使混凝土初始开裂时间相比土工布养护推迟了约6.65%,裂缝宽度降低了约70.67%; 养护剂养护下混凝土初始开裂时间相比土工布养护提前了约0.77%,裂缝宽度增加了约11.20%。2）减缩剂养护使平板总开裂面积相对于土工布养护减少了46.97%;养护剂养护使平板总开裂面积相对于土工布养护增加了约7.15%。研究表明: 减缩剂养护可以明显改善综合管廊混凝土的抗裂性能,而当混凝土养护剂养护方法不当时对提高混凝土抗裂性能的效果不明显。     

我是传奇

正保时捷919 Hybrid性能之强可以肆意叱诧耐力赛场,攻城掠地,好不风光。开着它是一种什么样的感觉,保时捷运动赛车部门给了evo杂志一个极其宝贵的机会保时捷把这台919 Hybrid LMP1当做70周年纪念庆典的一部分就已经佐证了这台勒芒系列赛车拥有超越历史的特质:技术上大胆进取;功能性上极为稳定;最重要的,它令人发指地快。Veni, Vidi, Vici,我来,我见,我征服,919在各种厮杀角力之后一次又一次站在了耐力赛领奖台的顶端,它的成绩之好恐     

A study of polygonal wheel wear through a field test programme

High magnitude impact loads caused by polygonal wear of the wheels have been associated with in-service failures of structural components of high-speed railways, although the mechanisms leading to wheels’ polygonalisation is not yet fully understood. In this study, a long-term field test programme is undertaken and the data are analysed to gain better understanding of the growth in polygonal wear, and its characteristics and correlation with the axle box acceleration. The field measurements on a high-speed railway involved monitoring of wheels profiles between successive re-profiling of the wheels so as to identify the rate of growth of wear in addition to the axle box acceleration. The data suggested rapid growth in wheel wear, which could be characterised by polygonal wear of nearly 18th and 19th harmonic order. It is further shown that the magnitude of axle box acceleration increased considerably with increasing wear magnitude of the wheel.     

填石路堤压实方法的评价

介绍填石路堤的几种压实方法、施工工艺、质量检测方法及研究情况,并提出了目前研究中存在的问题及其解决的初步方法。     

努力改进我国铁路集装箱货物运到期限

经过近一个世纪的发展,集装箱运输凭借其明显的优势成为未来货物运输的发展方向,而利用集装箱开展内陆运输尤其是国际货物联运,已成为发达国家铁路发展的一个重要趋势,我国铁路也不例外.特别是进入90年代以来,我国铁路集装箱运输有了较快发展,然而与国外铁路以及国内同行业相比较为滞后,铁路集装箱运输质量还很低,尤其是铁路集装箱运到期限水平较低,仍存在不少问题,迫切需要解决.     

基于霍尔位置传感器的永磁同步电机方波启动问题研究

针对基于霍尔位置传感器的永磁同步电机启动不稳定的情况,本文提出了永磁同步电机180°方波电流启动,高速后切换到正弦波电流方法。以STM32F103为核心主控芯片,搭建硬件系统和软件算法,实验结果表明本控制策略能够实现满载启动和加速过程,电机运行平稳。