简谐移动荷载下轨道结构响应研究

为了分析简谐移动荷载所导致的粘弹性地基上无限长轨道的振动传播现象,在随荷载移动的动态坐标系下联立轨道的横向振动微分方程,引入边界条件得到瞬态响应的解析表达式,分析梁在不同激振频率和运行速度作用下的轨道结构瞬态反应。结果表明:轨道结构存在临界速度。如果荷载运行速度小于最小临界速度,那么振动只在移动荷载处出现。如果荷载运行速度处于非零最小临界速度附近,轨道结构运动剧烈。如果荷载速度超过最小临界速度时,振动则可以波及整个结构。     

基于现场试验的水文地质参数计算可视化程序设计与应用

水文地质参数的计算工作一直是工程地质和水文地质界工程师们所关注的重点问题之一,传统的计算方法比较繁琐、费时,国内外目前也没有比较全面的水文地质求参软件,因此,本文利用Visual Basic语言研究开发了一款基于现场试验的水文地质参数计算的新型软件SHP,通过数据库调用Excel文件录入数据,利用最小二乘法原理拟合直线。实现了手动配线和自动配线两种方法求参。通过南京市玄武湖隧道工程实例的校验,结果表明,该软件实用性强、计算精度较高、人机交互简单,满足工程需要。     

Substrate Stimulated Orientation for Pure Aluminum

Oriented materials are of great importance, but their formation is rarely described. Here, nine Al/Al₂O₃ systems were designed to identify the dominant factors. Electron back-scattered diffraction indicates that the new Al crystal(s) with one or multiple orientation(s) can be stimulated by one single-crystal Al₂O₃ substrates. Synchrotron radiation diffraction shows that the preferred orientation(s) is/are determined based on the initial stage of the liquid–solid transition. The nonpreferred orientation can be suppressed through competition.

     

The Influence of Hydrogen Concentration in an Ar–H2 Mixture on the Electrical Properties of Solid Oxide Fuel Cells

Powder Metallurgy and Metal Ceramics - Fuel cells are today among the most efficient and environmentally friendly devices for the production of electricity. They are developing rapidly and are...     

沥青加注池的设计和制作

沥青混凝土拌和成套设备目前在高等级公路领域应用非常广泛,由于生产厂家通常不配置相应的沥青加注池,给沥青的灌装造成不便。根据工程实际需求,自行设计制作出与J4000型沥青拌和设备配套使用的沥青加注池,实际使用效果良好,沥青灌装效率高。介绍沥青加注池的主要组成及各组成部分的设计过程。     

混合的记忆

<正>春节少不了同学聚会,而今年恰是我的母校——百年名校雅礼中学的新建教学楼落成后的第一个春节。在大家漫不经心的回忆里,仍旧是斑驳的红砖房与房子后面的那个院子。席间,有人感叹,真是找不到那旧时的影子了。我知道改变一个建筑行为的最终目的大概是将一个平衡改变为另一个平衡。日子的飞奔也大抵是与遗忘成正比的,当多年后的今天,我们能掏出时间来回忆往事,是我们的日子总算开始慢了下来的证据。因为新教学楼大部分是自己的手笔,带着对孩     

Removal of Lissamine Red From Wastewater Using Waste Materials

Feasibility of a waste material, flyash, as a material for purification of wastewater containing Lissamine Red has been studied. Effects of time and concentration, temperature and pH on the removal of the dye have been studied. Lower concentrations favour the uptake of dye from water and the maximum removal was observed at a dye concentration of 20 mgL m 1 , 30°C, pH of 7 and adsorbent particle size of 53 µm. Dynamics of the uptake was studied using Lagergren's equation. The mass transfer coefficient was found to be 0.05 cmmin m 1 at a concentration of 20 mgL m 1 , 30°C and 53 µm particle size.     

廊坊市南水北调配套水厂以上输水管道工程土工试验指标分析

本文主要阐述了廊坊市南水北调配套水厂以上输水管道工程土工试验指标,并对其进行了详细地分析。     

上海三菱电梯智能制造技术应用点滴

1 装备制造业发展形势 制造业是国民经济的物质基础、国家安全的重要保障、国民经济高速增长的发动机及国家竞争力的主要体现。回顾世界制造业的发展历史,在19世纪末初步形成的制造业,主要生产方式是机械化加上电气化的批量生产。20世纪上半叶,以机械技术和机电自动化技术为基础的制造业的生产得到空前发展,以大批量生产为主的机械制造业成为制造活动的主体。近30年来,     

Collapse analysis of real RC spatial structures using known failure schemes of ferro‐cement shell models

Large‐span reinforced concrete (RC) shells collapses that occurred in the last decade caused many death toll as well as significant losses to national economies. The most famous cases were the collapse of the aqua park cover in Moscow on February 2004 and the 2E terminal roof destruction at Charles de Gaulle Airport near Paris on May 2004. Following the publications of the appropriate commissions that have studied the reasons of these events, the influence of concrete creep and changes in the shell geometry on buckling of RC thin‐walled shells was not properly considered in the design. This study is focused on buckling of such shells, taking into account geometrical and physical nonlinear behaviour of compressed concrete. Other important reasons of concrete shells collapse are also analysed. The study is based on available experimental and theoretical investigations of ferro‐cement shells' models previously performed by the first author. The results of these investigations, obtained for small‐scale ferro‐cement models of thin‐walled shallow RC shells, are discussed. Behaviour of the tested models is compared with that of the above‐mentioned real shells and similar structures, which also collapsed. The critical buckling loads for the shells are obtained. It is shown that these loads are lower than the actual ones; thus, the shells buckling was unavoidable. To prevent brittle shell failure, they should be designed using other dominant failure modes that appear before the buckling. Possible failure schemes of real RC shells can be predicted using dominant failure modes obtained by laboratory testing of scaled models. Copyright © 2012 John Wiley & Sons, Ltd.