对铁路客运专线耐久性混凝土电通量试验方法的探讨

电通量试验是评价混凝土耐久性的重要试验之一。介绍电通量试验相关技术,并基于客运专线工程实际,着重探讨电通量试验技术中存在的若干不足和适用范围,对同类工程试验工作具有一定指导意义。     

Hepatic CT image query based on threshold-based classification scheme with gabor features

Hepatic computed tomography(CT) images with Gabor function were analyzed.Then a threshold-based classification scheme was proposed using Gabor features and proceeded with the retrieval of the hepatic CT images.In our experiments, a batch of hepatic CT images containing several types of CT findings was used and compared with the Zhao's image classification scheme, support vector machines(SVM) scheme and threshold-based scheme.     

A HOS-based blind signal extraction method for chaotic MIMO systems

A novel method to extract multiple input and multiple output （MIMO） chaotic signals was proposed using the blind neural algorithm after transmitting in nonideal channel. The MIMO scheme with different chaotic signal generators was presented. In order to separate the chaotic source signals only by using the sensor signals at receivers, a blind neural extraction algorithm based on higher-order statistic （HOS） technique was used to recover the primary chaotic signals. Simulation results show that the proposed approach has good performance in separating the primary chaotic signals even under nonideal channel.     

Feasibility of localizing in vivo micro-devices with electromagnetic methods

In order to measure the location of medical micro-devices in the gastrointestinal tract, electromagnetic methods were developed considering the magnetic permeability of human bodies. Two varieties of electromagnetic localization methods have been implemented： one uses direct current（DC） to generate the electromagnetic field, and the other uses alternating current （AC）. The two varieties of the localization principle were analyzed and relevant experiments were made. The experiments show that the alternating electromagnetic method acquires higher accuracy, higher stability and wider measurement range.     

Reflections on energy issues in China

Energy, which has a bearing on both economic and national security, is of importance and a major constraining factor to the economic and social development of China. The article analyses the current worldenergy status and development trend from the perspectives of resources, production and consumption and in thecontext of its implications on the environment and economic and social development, and explores opportunitiesand challenges for China's energy development. With a focus on the strategy of energy development in China,the author proposes a new energy development approach with Chinese characteristics whose main elementsare: energy-saving, high-efficiency, diversified development, environment protection, technology guidance andinternational cooperation. In other words, China is striving to build a reliable energy production, circulationand consumption system that is efficient, technologically advanced, low polluting and ecologically friendly. Along-term development strategy with priority on energy conservation, efficient utilization of primary energyand advanced electricity system is expounded in the paper. The author also describes the prospect of energytechnology development and stresses the implementation of energy strategy by further improving energy policyand related mechanisms, strengthening macro-management and the essential role of the market in resourceallocation so as to ensure the economic and social development of China through reliable energy supply.     

数字地铁信息资源集成研究

从地铁信息化建设的实际出发,提出了融合BIM(建筑信息模型)、GIS(地理信息系统)、SVG(可扩展矢量图)和其他业务数据的数字地铁信息资源集成模型。给出了数字地铁信息资源集成模型的数据构成和应用架构。通过上海轨道交通智慧车站的试点验证了模型的可行性。     

复杂运行环境下高速轮轨最佳撒砂增黏策略试验

在车轮-钢轨高速接触疲劳试验机上开展水、油和树叶等污染下的高速低黏着和增黏试验,通过最高速度200km·h-1的对滚试验,测得不同第三介质条件下的轮轨黏着-蠕滑特性曲线,研究增黏砂粒径和撒砂量对增黏效果的影响。结果表明:喷撒增黏砂可有效恢复各种污染下的轮轨黏着水平,使200km·h-1下轮轨黏着系数保持在0.18以上,低速下更高;增黏砂粒径在0.4~1.0mm范围内增大或撒砂量在40~100g·min-1范围内增加时,增黏效果均稍稍增强,综合考虑确定试验机的最佳撒砂量为40g·min-1、最佳粒径为0.85~1.0mm;考虑试验机与现场轮轨系统的尺寸差异、运行时复杂气流所致砂粒损失及适当冗余度等因素,建议现场最佳撒砂量为115~175g·min-1、最佳粒径为1.0~2.0mm;喷撒增黏砂会造成车轮接触表面的麻坑损伤,也是造成现场车轮踏面常见麻坑损伤的根本原因。     

霍尔油位传感器的应用设计

目前,油位传感器普遍采用铍青铜电刷加厚膜电阻形式,作为一类技术成熟的油位传感器,有着无可比拟的价格和技术优势,虽在行业中占据主导地位,但这种传感器也有难以克服的缺陷,在正常通电状态下一般很难达到预期的设计寿命。随着油价上涨,劣质汽油流入市场,汽油中硫磷等腐蚀性物质对厚膜电阻腐蚀严重;耐乙醇汽油的丁晴橡胶浮子在生产过程中残留有硫元素,溶解在汽油中会腐蚀厚膜电阻,这两方面是导致油位传感器使用寿命降低的关键因素。     

旧混凝土板再生集料用于水稳基层的工程特性

将旧水泥混凝土道板现场加工为再生集料,用于改造道路的稳定基层,能够达到节约能源、节省资源、循环利用的目的。但由于旧有水泥砂浆的影响,再生集料的性能指标离散性较大。通过在室内采取球磨手段进行再生集料表面松散砂浆的再处理,根据集料基本特性、水泥稳定再生集料强度及其路用性能的试验比较,获取其加工前后的性能改善效果。结果显示:再生集料抗压破碎能力有明显提高,吸水率有较大降低,能更好地满足我国现行规范稳定基层的集料及混合料的性能指标要求。     

铁路正交异性桥面上承钢桁梁典型病害分析及加固方法研究

以铁路32 m正交异性板桥面上承钢桁梁为研究对象,对典型裂纹病害进行分类描述。利用ANSYS软件,采用板壳单元,建立空间有限元模型,开展正常条件及极端条件下力学行为分析,按照设计规范计算得到开裂位置处局部点疲劳应力幅。通过考察各典型连接细节的构造特点及受力行为,结合数值模拟结果,对各典型病害的开裂原因进行分析。针对各类病害具体特征,参考国内外钢桥病害整治方案,对正交异性板桥面上承钢桁梁进行加固改造。结果表明:焊接缺陷、面外变形及支座脱空是该类桥梁出现裂缝病害的主要原因;通过高强螺栓拼接角钢增加连接细节局部刚度可有效提高结构疲劳强度,达到结构加固改造目标。