Cyclic strength of parts with overlapping zones formed by roller burnishing

The authors study residual stresses in and cyclic strength of shaft with overlapping zones formed during roller burnishing. The most significant decrease in fatigue strength is shown to occur in the presence of an overlapping zone with the areas arising due to a lowered roller burnishing pressure in the second pass. __________ Translated from Problemy Prochnosti, No. 3, pp. 144–148, May–June, 2006.     

Cross-Border Migration of Hong Kong Residents Under the 'One Country, Two Systems' Policy

Hong Kong is known as a migrant city because its population was sourced from mainland China, and because there has always been outflows of people to overseas countries, especially from the mid-1980s to mid-1990s. Emigration to mainland China has become a significant recent trend. This article discusses this phenomenon in the theoretical contexts of migration and trans-border residential development. It contends that the trend will intensify more quickly than other cross-border movements because the two systems are separated by a political border within one country, and because there are common cultural ties and rapid economic integration.     

Short beam three point bend tests in syntactic foams. Part I: Microscopic characterization of the failure zones

Scanning Electron Microscopic (SEM) studies were carried out on the failure surface of syntactic foam material tested in a short beam three point bend test (SBT) by employing 21 × 15 × 3 mm³ dimension bearing specimens. The syntactic foams were fabricated using glass microballoons in epoxy binder. The failure of the tensile, compression, and shear dominated regions were studied by SEM at different magnifications. The tensile region had characteristic features, such as partial debonding of the microballoons from the matrix and cracking of glass microballoons, apart from matrix cracking and some river pattern features. The compression side was characterized by crushing and collapsing of microballoons, resulting in accumulation of debris with no apparent river pattern for matrix‐rich regions. The midway positions of the SBT failed surface comprised of deformation bands in the matrix and occasional debonding of microballoons. The morphology recorded in the tensile and compression regions corroborated well with the results obtained on these foam samples in those specimens that were subjected to pure uniaxial tension and compression, respectively. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 673–679, 2005     

巨厚砂岩顶板“三带”范围的数值模拟与界定

为定量划分采空区上覆巨厚砂岩顶板的"三带"范围,根据数值模拟的应力与位移结果,提出"三带"的界定准则:将上覆岩层中主应力都为拉应力的区域定为冒落带;将只有一个主应力为拉应力的岩层高度定为裂隙带的上限。采用FLAC3D软件对开采过程中的顶板运动规律进行了数值模拟,模拟结果与实际观测结果一致。表明此界定准则可为地质条件相似矿区的顶板"三带"分布提供借鉴。     

Effects of T5 heat treatment on extrusion welds in AZ80 hollow profile

AZ80 hollow profile was produced by porthole-die extrusion. The mechanical behavior and microstructure characteristic of extrusion welds in AZ80 hollow profile during different T5 heat treatments were investigated. Five kinds of morphologies of β-Mg₁₇Al₁₂ were observed in turn in weld regions under various temperatures. Extrusion weld is not weakest region in AZ80 hollow profile in terms of hardness, the peak hardness of weld regions is roughly equal to the weld-free regions at different aging temperatures, which is attributed to similar volume fraction, morphology, and size of β-Mg₁₇Al₁₂ precipitate in weld regions and weld-free regions. The precipitate-free zones (PFZs) usually form near the welds interface in aging process, and the hardness of PFZs is usually lower than those of weld regions and weld-free regions. Aging at 200°C for 24?h is suitable heat treatment system for AZ80 hollow profile, which can achieve excellent mechanical property and simultaneously reduce the width of PFZs.     

黄河流域实施水功能区限制纳污红线管理的整体构想与初步实践

水功能区限制纳污红线管理是实行最严格水资源管理制度的核心内涵之一。黄河流域水安全问题是中国水安全问题的缩影,探索构建行之有效且具有黄河流域特色的纳污红线管理制度体系和工作格局,对于提高黄河流域水安全保障能力意义重大。针对黄河流域的水资源质量状况,探索建立流域与区域相结合、水利与环保相联合的黄河水资源保护管理体系,构建流域水功能区划及水资源保护规划体系,依法强化以入河排污口为重点的水功能区管理,积极探索水生态系统保护与修复,加强水质监测网络体系建设等一系列措施,为黄河流域实施纳污红线管理提供了良好的工作基础和能力支撑,并在此基础上阐述了黄河流域实施纳污红线管理的整体构想与初步实践。     

地震勘探技术在解释地质异常体的应用分析

地震勘探技术在控制煤层赋存形态方面有高于其它物探方法的优势,尤其在准确圈定小窑采空区、岩浆岩侵蚀、煤层露头、火烧区及冲刷带、陷落柱等地质异常体方面已取得了很好的效果,对煤矿产业的生产和建设都起到了举足轻重的作用。本文通过河北、新疆和山西等地煤矿采区三维地震勘探实例介绍了如何根据地震时间剖面表现的不同特征来确定和解释各种煤层地质异常体,并取得了良好的地质成果。     

ZDM软件在灌区渠道改建设计中的应用

ZDM软件广泛应用于水利水电设计行业,尤其是对灌区渠道、河道整治、供水管道、堤防加固等长线路工程的设计,可明显提高工作效率。介绍该软件在灌区渠道改造设计中的应用,重点为图纸绘制、图纸打印和工程量计算等工作。     

大跨悬索桥索梁锚固区疲劳养护概率优化方法

合理的桥梁养护规划应在养护费用与失效风险之间找到一个合理的平衡.将养护费用分为检测费用,维修费用与失效费用,将线弹性断裂力学、结构可靠度理论、全寿命成本分析法结合起来,提出了基于全寿命周期成本的焊接构件疲劳养护概率优化的方法.考虑了检测概率、养护决策者的维修意愿、维修措施概率和失效概率等多种因素,把桥梁养护优化问题变为在焊接结构或构件满足在生命周期内最小允许可靠度的基础下,养护总费用最小的问题,并提出了简化计算方法.以青草背长江大桥索梁锚固区的关键疲劳细节养护为例,研究了主要参数对最优检测时刻的影响,研究结果表明,考虑了失效成本后,最优疲劳养护时刻提前,折现率对养护费用影响明显.当车辆荷载逐年增加时,索梁锚固区在设计基准期内疲劳破坏风险增大,应引起足够的重视.