The Influence of Anchor Devices on the Performance of Retractable Type Fall Arresters Protecting Against Falls From a Height

Retractable type fall arresters are part of the equipment used for protecting people against falls from a height. They are an intermediate part between full body harness worn by a man and the structural anchor at the worksite. The most important task of retractable type fall arresters is to arrest people’s falls and to reduce their harmful consequences. Information received from users as well as laboratories testing protective equipment indicates that the performance of such equipment is incorrect under specific conditions. The paper is concerned with an analysis of the conditions in which retractable type fall arresters demonstrate intermittent performance and with an explanation of that phenomenon. The results of tests investigating anchor devices and the performance of retractable type fall arresters are presented. External and internal factors contributing to intermittent performance have been determined and guidelines for safer use of these devices have been developed.     

改性植被混凝土基材力学与植生试验研究

为探明羧甲基纤维素钠(CMC)与麦秸秆纤维对植被混凝土基材力学与植生性能的影响,通过直剪试验、植生试验研究了改性后植被混凝土基材(简称改性基材)的抗剪性能与黑麦草生长性能.结果 表明:①改性基材的剪切强度随CMC掺量的增加呈先增后减的变化趋势,0.5％CMC掺量时基材的剪切强度出现峰值,而随纤维掺量的增加改性基材剪切强...     

Pulmonary Functions of Welders in Gas Transmission Pipelines in Iran

This study evaluated the influence of welding on pulmonary functions in welders. Spirometry tests were performed before and after work shift in 91 welders and 25 clerks (control group). We examined forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC ratio and forced expiratory flow 25%-75% (FEF 25–75). Significant differences were found for FVC and FEV1/FVC between welders and the control group in pre- and post-shift measurements (p < .001). In welders, smoking and nonsmoking habit had no significant effects on any pulmonary indices before or after shift. Work experience and fume concentrations also had no significant effects on the majority of spirometric indices (p > .05). Most welders had at least 1 of the respiratory symptoms. Significant differences were found between pre- and post-shift indices (as percentage of predicted values calculated with spirometer) and between the welders engaged in some welding tasks and the control group before work shift. This study documented work-related changes in pulmonary functions in the welders and marked drops in these functions without symptoms in some welders.     

Estimation of Aerobic Capacity and Determination of Its Associated Factors Among Male Workers of Industrial Sector of Iran

Introduction. The aim of this study was to estimate maximal aerobic capacity (V_O2max), to determine its associated factors among workers of industrial sector of Iran and to develop a regression equation for subjects’ V_O2max. Methods. In this study, 500 healthy male workers employed in Shiraz industries participated voluntarily. The subjects’ V_O2max was assessed with the ergocycle test according to the Åstrand protocol. Required data was collected with a questionnaire covering demographic details (i.e., age, job tenure, marital status, education, nature of work, shift work, smoking and weekly exercises). Results. The subject’s mean V_O2max was 2.69 ± 0.263 L/min. The results showed that there was an association between V_O2max and age, BMI, hours of exercise and smoking, but there was no association between V_O2max and height, weight, nature of work and working schedule. On the basis of the results, regression equations were developed to estimate V_O2max. Conclusion. Final regression equation developed in this study may be used to estimate V_O2max reliably without the need to use other laboratory instruments for aerobic measurement.     

环氧丙烷储罐空气泡沫灭火试验研究

环氧丙烷为低沸点水溶性可燃液体,由于其饱和蒸汽压大,灭火困难,此前,国内外未对环氧丙烷进行过大型工程应用灭火试验研究。为研究空气泡沫对环氧丙烷储罐的灭火性能,分别对环氧丙烷进行了0．25m^2油盘探索性试验、1．73m^2油盘泡沫灭火剂选型试验和直径3．5m储罐工程应用灭火试验。试验结果表明,空气泡沫难以扑灭环氧丙烷储罐火灾,在直径3．5m储罐上,虽然采用了灭火性能较好的泡沫液,且使用了较大的供给强度和较长的供给时问,但仍难灭火。在试验基础上,对环氧丙烷储罐的消防要求提出了建议。     

广东省能源消费与经济增长动态关系研究——基于环境库兹涅茨曲线假说

基于库兹涅茨曲线模型,对广东1980-2010年经济增长与能源消费的动态关系进行了实证研究.结果表明,在整个研究期间,广东省人均能源消费与人均经济增长协整关系呈单调正相关,1999年的结构断点使两者的协整关系发生变化,断点分隔的两个时间段内均符合倒“U”型模型,但曲线拐点后移.广东省现处于倒“U”型曲线的左端,EKC理论拐点为23253元（1978年不变价）.广东省应采取积极有效的节能减排政策,引导促进倒“U”型曲线弧度降低,让拐点提前到来.     

大气环境下风电塔筒金属材料的应力腐蚀

塔筒金属材料在大气中的应力腐蚀会导致脆性断裂,从而对产生严重的后果。本文重点论述了应力腐蚀的几种腐蚀机理以及Cl-对应力腐蚀的影响,并介绍了应用较广的慢应力速率试验方法。     

新疆“三十里风区”输电线路复合绝缘子故障分析

复合绝缘子是超高压输电线路中的关键设备之一,确保其可靠运行是维护电网安全的前提。新疆乌鲁木齐至吐鲁番750kV输电线路途径"三十里风区",当地10米高度处最高设计风速为42m/s,这对复合绝缘子的长期运行是一个巨大挑战。强风下的绝缘子伞裙摆动导致其根部材料疲劳,进一步产生微观裂纹,最终导致绝缘子撕裂故障。本文通过气候环境调研,分析了当地气候环境特征;通过故障分析,初步探明乐儿复合绝缘子伞裙撕裂过程;通过风洞实验研究,得到了伞裙在流体中的动态现象。通过以上分析,对于这项特殊微气候环境下的外绝缘典型故障,本研究探明强风下伞裙动态过程,并在伞裙故障产生原因方面进行一定探索,为最终解决该问题提供了有力的技术参考。     

静电放电测试标准解析

设备在遭遇不同程度的静电放电时,其自身的安全性和可靠性面临着巨大的考验。GB/T 17626.2-2006、GJB 1389A-2005和RTCA/DO-160F均描述了静电放电试验项目。比较分析这三个标准对该项目在试验目的、适用对象等方面的差异,可以发现这三个标准的考核要求和试验方法也不尽相同。GB/T 17626.2-2006是一项基础性标准,适用于各种电子设备;GJB 1389A-2005主要针对垂直起吊、空中加油系统以及军械分系统,考核其在装卸、运输和垂直补给过程中的安全性和可靠性;RTCA/DO-160F主要考核的是民航空运设备在经受静电脉冲后执行预期功能的能力。     

盐雾腐蚀及其试验中需要注意的几个问题分析

本文介绍了产品进行盐雾腐蚀试验的必要性,对中性盐雾试验、醋酸盐雾试验、铜盐加速醋酸盐雾试验、交变盐雾试验分别进行了描述。重点介绍了盐雾试验中需要注意的几个问题:试样预处理、试样的放置、盐溶液pH值及试验温度,并探讨了一些对应的预防措施。