The Open City and the e[ad] School of Architecture and Design

Located in Ritoque on central Chile's Pacific coast, Open City is a unique community established in the 1970s by faculty members from the nearby e[ad] school of architecture at the Pontifical Catholic University of Valparaíso. Here Professor David Jolly Monge , a founding member of the Open City, and Guest-Editors Christian Hermansen Cordua and Michael Hensel describe how the construction of structures on the site offer the collective community and students alike ongoing opportunities for ‘thinking, research and experimentation’.     

QTZ250塔吊增加独立自由高度的研究

在建筑施工中常因施工现场狭小、施工现场外存在较高的已建建筑物或其它障碍物以及土方基坑开挖深度和群塔施工的影响,使塔吊独立自由高度常常不能满足要求.针对这种情况,以实际工程为例,对塔吊增加独立自由高度进行了详细分析和计算,并提出了相关建议,在类似情况下亦具有参考作用.     

基于高通量测序技术分析恩施州淡豆豉的细菌多样性

以恩施州不同产地5 种细菌型淡豆豉作为实验对象,利用Illumina PE250高通量测序技术,对5 种淡豆豉的细菌群落结构及多样性进行研究。结果表明：5 种恩施州豆豉的微生物组成多样,共鉴定出17 门、24 纲、43 目、78 科、152 属以及93 种。其中核心优势细菌门为厚壁菌门（Firmicutes）,其次为变形菌门（Proteobacteria）、蓝细菌门（Cyanobacteria）和放线菌门（Actinobacteria）,优势菌属为芽孢杆菌属（Bacillus）的嗜热淀粉芽孢杆菌（Bacillus thermoamylovorans）和史密斯芽孢杆菌（Bacillus smithii）。各样品间,优势菌属相同,但相对丰度差异较大,其余次要菌属的种类和相对丰度均存在较大差异,显示出恩施淡豆豉菌群结构的多样性。     

基PXA250的嵌入式Linux系统

分析了Linux在嵌入式系统开发中的优势和PXA250的主要特征,介绍了基于PXA250的硬件平台上移植Linux的关键技术和实现过程,包括建立开发环境、Linux引导、中断处理、设备驱动以及文件系统。基于PXA250的硬件平台同Linux操作系统配合,提供了一个速度快、体积小、功耗低且应用程序接口丰富的平台,它在未来的移动计算和通讯终端领域有较好的应用前景。     

250m超高钢筋混凝土烟囱套入式爆破拆除的数值模拟

研究250 m 高钢筋混凝土烟囱在狭窄环境下进行套入式爆破拆除的可行性。运用 LS-DYNA 软件分别模拟无风载荷作用和有风载荷作用下烟囱的倒塌过程。使用 ALE 多物质流动和流固耦合算法模拟风载荷的作用;采用共节点分离式钢筋混凝土模型,并对混凝土单元和钢筋单元进行受力分析。研究表明在爆破切口形成后,钢筋对上半段混凝土的有效支撑时间在0.5 s 左右,且风速 V =10 m/ s 时为爆破拆除的临界环境,进而证实了在狭窄环境条件下超高烟囱套入式爆破拆除具有可行性。     

SINAMICS G120/PM250再生回馈型变频器在游梁式抽油机上的应用

本文主要介绍了西门子新一代再生能量回馈型变频器G120-PM250功率模块在游梁式抽油机上的成功应用,实现了游梁式抽油机运行时再生回馈电能的高效运行,达到了节能降耗和提高混油产量之目的。     

ASSISTED CRACK GROWTH IN MARAGING STEEL WELDS BY GASEOUS HYDROGEN

Abstract— The effects of environmental hydrogen content on fatigue crack growth rates (FCGRs) in T-250 maraging steel plates and laser welds were investigated. The influence of ageing treatments on fatigue characteristics of the alloy was also studied. Experimental results revealed that the accelerated FCGRs in the presence of hydrogen were always associated with changes in fracture modes that appear in compact-tension specimens. Even for overaged specimens with excellent resistance to gaseous hydrogen embrittlement, such an acceleration of crack growth in hydrogen could not be avoided. The crack path of underaged specimens in hydrogen was found mainly along prior austenite boundaries for steel plates and along coarse columnar boundaries for welds. In gaseous hydrogen, peak-aged welds exhibited intergranular and quasi-cleavage mixed fracture modes, compared to mainly quasi-clevage for similar aged steel plates. Hence, the enhancement of crack growth in hydrogen was more pronounced for the welds. Overaged welds showed higher FCGRs than the same aged steel plates only in hydrogen and for Δ K values greater than 20MPa√m.     

KYZ—250/550型直流架线电机车脉冲调速器的设计与应用

煤矿电机车运输是煤炭生产的重要环节 ,目前大多数煤矿电机车的调速器仍使用原始的调速方法 ,缺点多 ,效率低 ,难以满足快速发展的煤炭生产的需要。KYZ— 2 5 0 5 5 0型直流架线式电机车调速器就避免了以上弊病。文章讨论KYZ— 2 5 0 5 5 0型直流架线电机车脉冲调速器在煤矿运输中所体现的优势及特点。     

2014 年度ENR 国际承包商250 强探析

由美国《工程新闻记录》评选的国际承包商250 强榜单是反映全球工程承包市场发展趋势的权威指南。根据2014 年度ENR 国际承包商250 强的统计数据,从收入规模、盈亏水平、地区分布及行业领域等多个角度对过去一年国际承包企业的海外市场表现进行分析,并对国际承包市场的波动特征和热点问题进行了剖析。针对中国内地企业在榜单中的表现进行了详细的解读,同时对近5 年中国内地企业的表现进行了比较研究,并对近5 年国际承包商10 强的变化进行了总结。通过对国际承包市场及规模企业的基础数据进行深度分析,为研判国际工程承包市场的变化趋势,服务中国内地企业开拓海外市场提供信息支撑和决策支持。     

Microstructure and Hardness of T250 Maraging Steel in Heat Affected Zone

 Electron beam (EB) welding was used in T250 maraging steel, microstructures of both base material and heat affected zone (HAZ) were investigated by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and microhardness was tested. The results showed that during EB welding, the HAZ of T250 maraging steel exhibited a continuous gradient structure. The microstructure of the entire HAZ, from fusion line, could be divided into four zones: fusion zone, overheated zone, transition zone, and hardened zone. The microhardness showed a distinct regularity in each area. The softest region was the fusion zone, whereas the hardest was the hardened zone. In the overheated zone, the hardness increased as the grain size decreased. Furthermore, in the transition zone, the hardness level dropped noticeably. The peak temperature during the thermal cycle had a great influence on the formation of reverted austenite and dissolution of the precipitated particles, which contributed a lot to the microstructure and hardness of this material.