Failure analysis of aluminum cable steel reinforced (ACSR) conductor of the transmission line crossing the Paraná River

The failure of the conductor of the 460 kV overhead transmission line located along the crossing of the Paraná River was investigated. As a result of this failure, a blackout took place in the southern states of Brazil in January of 2002, reaching approximately 67 million inhabitants. Investigation of the external aluminium layer of the ACSR conductor near the fracture showed typical static deformation marks and dynamic fretting wear tangential marks, both associated with the presence of Al₂O₃ debris. Additionally, encrusted silicon particles were observed on the external surface of the strands. The internal Al layer showed elliptical deformation marks also associated with Al₂O₃ debris. Both Al₂O₃ and Si particles are efficient abrasive material, which associated with slight relative motion of metallic surfaces (clamp/strand and strand/strand) can promote fretting wear. Two types of fracture surface of the Al strands were identified: 45° and quasi-normal surfaces, the former being the predominant type. Delamination and particle detachment were the mechanisms of superficial degradation observed on the Al strands, indicating that the rupture of the strands occurred under a gross slip fretting regime induced by sub-conductor oscillation. Inspection of the internal surface of as-cast Al–10%Si spacer clamps revealed different stages of intense circumferential wear caused by the preferential cracking and particle detachment of the eutectic constituent of the as-cast microstructure. This intense wear reduces the clamping contact pressure, which allows higher displacement amplitude and leads to the critical fretting regime. Finally, a few suggestions are discussed to minimise the occurrence of future failures.     

Effects of modeling means on properties of monitoring models of spot welding quality

Analyzing and modeling the relation between monitoring information during welding and quality information of the joints is the foundation of monitoring resistance spot welding quality. According to the means of modeling, the known models can be divided into three large categories: single linear regression models, multiple linear regression models and multiple non-linear models. By modeling the relations between dynamic resistance information and welding quality parameters with different means, this paper analyzes effects of modeling means on performances of monitoring models of resistance spot welding quality. From the test results, the following conclusions can be drawn: By comparison with two other kinds of models, artificial neural network (ANN) model can describe non-linear and high coupling relationship between monitoring information and quality information more reasonably, improve performance of monitoring model remarkably, and make the estimated values of welding quality parameters more accurate and reliable.     

蓝疆号起重铺管船托管架拖挂结构的质量及进度控制

蓝疆号起重铺管船是一艘集起重、管道铺设于一身的多功能新型船舶,在铺管作业系统中,设有一连接船体与托管架的独立结构——拖挂结构。介绍这个由特厚高强钢板组焊而成的结构在制造过程和现场施工中的质量控制及进度控制,供从事工程管理人员参考。     

矿渣浆降失水剂GJ-1的应用

针对矿渣浆水灰比较大、固相含量相对较少、自由水比较多、失水量较大的特点，用实验的方法优选出了降失水剂GJ－1。实验和现场应用表明，GJ－1具有许多优点：（1）用量少，降失水效果显著；（2）配伍性良好，GJ－1的加入不影响激活剂、助剂、分散剂以及其它添加剂的作用效果；（3）耐温性良好，耐碱性比较好；（4）具有润湿、润滑作用，有利于泵送；（5）有一定的缓凝作用；（6）提高矿渣石的高温高压强度，GJ－1加量在0．6％以上时能将矿渣石的高温高压强度提高3－4MPa；（7）增粘不明显；（8）具有一定的悬浮能力；（9）强化矿渣浆的直角稠化，加入GJ－1的矿渣浆可以应用于防窝固井技术，能够解决长封固段井的固井难题和低密度矿渣浆的沉降稳定性问题，保证施工安全，提高固井质量。     

发展我国制革企业刍议

中国已入世 ,制革业将拥有无限机遇 ,但制革厂还现存一些亟待解决的问题。解析了制革厂的技术创新、经营管理等方面的问题。     

提高集聚纺纱效率的可行性研究

本文主要讨论了精梳工序和普梳工序对集聚纺纱线质量和加工效率影响的测试结果。     

MODELING OF WATER DYNAMICS AND POLLUTANT SPREADING IN THE LUOMAHU RESERVOIR FOR WATER TRANSFER FORM SOUTH TO NORTH OF CHINA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＷａｔｅｒＴｒａｎｓｆｅｒＦｒｏｍＳｏｕｔｈＴｏＮｏｒｔｈＰｒｏｊｅｃｔ(ＷＴＦＳＴＮＰ)ｉｓａｇｒｅａｔｄｅｃｉｓｉｏｎｔｏｓｏｌｖｅｔｈｅｐｒｏｂｌｅｍｏｆｗａｔｅｒｓｈｏｒｔａｇｅｉｎｔｈｅｎｏｒｔｈａｎｄｃｅｎｔｒａｌｐａｒｔｓｏｆＣｈｉ ｎａ .Ｔｈｉｓｐｒｏｊｅｃｔ ,ｉｎｃｌｕｄｉｎｇＥａｓｔ ,Ｃｅｎｔｒａｌ ａｎｄＷｅｓｔ Ｌｉｎｅ ,ｗｉｌｌｄｒａｗｗａｔｅｒｆｒｏｍｔｈｅＹａｎｇｔｚｅＲｉｖｅｒｔｏｔｈｅｎｏｒｔｈａｎｄｃｅｎｔｅｒｏｆＣｈｉｎａｓｏｔｈａ…     

0.89dtex细旦涤纶短纤维工艺优化探讨

介绍了纺制 0 89dtex× 3 8mm细旦涤纶短纤维的工艺技术特点 ,着重讨论了熔体温度、纺丝速度、冷却条件等工艺对原丝性能及产品质量的影响     

钻机柴油机的动向和190系列柴油机的发展

本文概括介绍了国内外钻机柴油机发展的水平及动向,比较了国内钻机柴油机与国外钻机柴油机在发展上的差距。重点介绍了作为国产钻机主要动力的190系列柴油机的发展状况及最新技术在该机型上的应用。     

变长线扫描选择性激光烧结快速成型工艺的质量和效率优势分析

本文分析变长线扫描选择性激光烧结快速成型工艺对点扫描工艺的质量和效率优势.对二者光学系统结构作分析对比,对焦斑和线束上的功率密度作计算对比.变长线扫描系统采用的扫描方式和聚焦元件使线束宽度小且恒定,线束功率密度与点扫描焦斑的相当.变长线扫描选择性激光烧结快速成型工艺的质量优势是明显的,效率比点扫描工艺提高一倍左右.