非煤系构造连通型瓦斯隧道超前地质预报技术

穿越非煤系地层的隧道中的瓦斯的不可预见性很大,非煤系构造连通型瓦斯隧道是穿越非煤系地层的典型代表,现阶段对这类隧道还没有系统的超前地质预报技术,给施工安全造成了很大的威胁。为了准确预报非煤系构造连通型瓦斯隧道中的瓦斯运移途径,避免安全事故的发生,通过对现有超前地质预报技术包括地质法和物探法在非煤系构造连通型瓦斯隧道中适用性的分析,构建非煤系构造连通型瓦斯隧道的综合超前地质预报体系,并通过在肖家梁铁路隧道施工中成功应用,说明提出的超前地质预报技术是可行的。     

金融IC卡在轨道交通领域的应用研究

介绍了非接触式金融IC卡在城市轨道交通中的应用前景,分析了该应用方案的系统总体结构、交易流程、资金清算及安全体系等。分析表明,经过各相关单位相关应用系统的协调建设,可以实现非接触式金融IC卡在城市轨道交通中的应用。并根据具体案例,介绍了城市轨道交通应用金融IC卡时相关系统的主要改造内容。     

渝黔铁路瓦斯突出隧道安全施工管理实践

结合渝黔铁路天坪隧道横洞瓦斯突出工区施工特点,介绍瓦斯突出隧道施工安全管理的组织措施、技术措施及管理措施,并对瓦斯突出隧道通风、施工供电及设备、安全避险六大系统、防突技术措施、瓦斯监测及应急救援等进行研究,实践证明各项管理措施安全可靠,为类似铁路瓦斯突出隧道安全施工管理提供参考。     

基于单分类算法OSVM船用燃气轮机状态评估

针对船舶综合监控系统中存储有海量设备正常运行时的数据没有得到充分利用，此外设备退化时的故障数据难以获取，无法训练传统的多分类退化检测模型，提出利用单分类算法OSVM来建立模型,从而实现退化检测，在该过程中只需用正常样本数据来训练模型，并在一个经过实船数据验证过的模拟器产生的数据集上进行了实验。结果显示，只需要400个正常样本就可训练出准确的退化检测模型，该模型在精确度，召回率，特异性，正确率，AUC五个指标都有很好表现，此外，该退化检测模型有很好的扩展性，也可被用于其他机械设备的状态评估中。     

Real-world gaseous and particle emissions of a Bi-fuel gasoline/CNG Euro 6 passenger car

The objective of the present study is the assessment of the environmental impact of a bivalent (bi-fuel) vehicle, running either on gasoline or compressed natural gas (CNG). To that aim, a Euro 6 passenger car was tested under various real-world driving conditions. In order to cover the full range of conventional powertrains currently in the market, the tests were also repeated on a Euro 6 diesel passenger car. Both cars were driven in two routes, the first complying with the regulation limits and the second going beyond them. Carbon monoxide (CO), nitrogen oxides (NO_x) and particle number (PN) emissions were recorded using a Portable Emissions Measurement System (PEMS). Apart from the aggregated emission levels, in g/km, the exact emission location along the route was also assessed. Natural gas proved beneficial for CO and PN emissions, the level of which always remained below the respective legislation limits. On the other hand, under the dynamic driving conditions with gasoline, the relevant limits were exceeded. Cold start, occurring at the beginning of the urban part, and motorway driving were identified as major contributors to total emissions, especially in gasoline mode. However, the application of natural gas was associated with a penalty in NO_x emissions, which were significantly increased as compared to gasoline. Local peaks within the urban part were identified in CNG mode. In any case, the diesel vehicle was by far the highest NO_x emitter.     

铁路建设项目竣工结算方法探索——以某铁路工程竣工结算为例

2004年以来,全国掀起了一轮铁路建设的高潮,一条条高速铁路和客运专线相继建成开通,已建成开通运营的项目,有的正在办理工程竣工结算工作。笔者了解到,因为没有明确的方法与指导,多数项目竣工结算工作开展艰难。此文依据现行铁路投资管理模式、铁路建设工程承发包合同规定,论述铁路建设项目竣工结算的方法及组卷要求,供相关从业人员参考使用。     

后背门气弹簧设计探析

本文首先论述了压缩式气弹簧的结构以及工作原理。以后背门气弹簧布置为例,详细阐述了气弹簧的布置型式;安装点的位置和最大开启角度的确定;有效行程和最小支撑力的计算。     

发动机渗漏气体及其检测

气缸压力降低是造成车辆行驶无力，油耗增加的主要原因。为了准确地测出故障部位，可在测量完气缸压力后，针对压力低的气缸，采取简易的就车检查方法进行确诊。根椐气缸漏气量（率）检测仪结构与工作原理，文章介绍了采用压缩空气检查发动机渗漏部位、检测方法和检测参数标准；同时以曲轴箱窜气为例，进行发动机渗漏气体的检测。通过检测结果再对其使用、维修和配件质量等情况进行具体的分析和判断，找出故障根源予以修复。     

Lengthscales of motions that control air–water gas transfer in grid-stirred turbulence

The relationship between the gas transfer velocity and turbulent lengthscales is investigated experimentally in a grid-stirred turbulent flow. The horizontal velocity field at the water surface is measured using particle image velocimetry (PIV). The gas transfer velocity for oxygen is obtained through reaeration experiments. In addition, the gas transfer process by surface-renewal eddies is visualized using laser-induced fluorescence (LIF) technique, in which carbon dioxide is used as the tracer gas. The definition of the Taylor microscale holds that the root-mean-square (RMS) of the surface divergence is expressed by the square root of the turbulent kinetic energy divided by the Taylor microscale. Experimentally obtained data support this scaling. They show the gas transfer velocity to be proportional to the square root of the RMS of the surface divergence. These experimental results imply that the Taylor microscale is an important parameter for gas transfer velocity at the air–water interface. These relations indicate that a nondimensional gas transfer velocity is proportional to the − 1/4 power of a turbulent-macroscale Reynolds number, which is similar to a small-eddy model, assuming that turbulent eddies with the Kolmogorov scale control the gas transfer process. However, this Reynolds number dependence does not necessarily mean the superiority of turbulent eddies with the Kolmogorov scale in the gas transfer. The LIF visualizations in horizontal and vertical planes close to the air–water interface indicate that the horizontal CO₂-concentration field has a fine spatial pattern, which resembles that of the surface divergence field, and that surface-renewal motions observed in the vertical plane have a larger lengthscale than the Kolmogorov scale. We infer from both PIV and LIF results that the Taylor microscale is an important lengthscale for air–water gas transfer.     

N2O／C2H5OH单喷嘴燃气发生器研究

本文以引射器高温引射工质使用需求为背景,提出一种以一氧化二氮/酒精为工质的燃气发生器燃烧方案,并设计、加工了单喷嘴燃气发生器,进行了热试车试验,结果表明:燃烧方案可行,燃气发生器喷嘴设计合理,具有分级启动能力,可在较宽的流量范围内稳定工作。