Optimization of resistance spot brazing process parameters in AHSS and AISI 304 stainless steel joint using filler metal

The aim of this research study was to determine optimal resistance spot brazing parameters for joining between AHSS and AISI 304 stainless steel by using filler metal. The key parameters investigated in this study consist of the brazing current, electrode pressure and brazing time. The Taguchi method was applied to the design of experiments. Signal-to-Noise ratio was introduced in the study to identify optimal levels from the process where input parameters yield increased shear strength. Brazing was thus implemented with 5,000A brazing current, 0.70 MPa electrode pressure, and 1.50s brazing time. The maximum shear strength obtained was 54.31 N·mm⁻² in accordance with input parameter settings. In addition, Cu-rich phase and Ag_0.4Fe_0.6 intermetallic phases were found at the interface zone.     

村民自治对农村社会稳定的双面效应

村民自治对农村社会稳定起着正面效应;异化的村民自治对农村社会稳定起着负面效应。鉴于此,为在农村社会发展中实现农村社会稳定,就要不断强化其正面效应,弱化其负面效应。     

虚拟现实技术在消防训练中的应用

在对虚拟现实训练系统分类论述的基础上,探讨了虚拟现实技术在消防训练中的应用及优势,阐述了该领域在国内外的研究现状和发展前景,并指出了有待进一步研究的问题。     

新型防火板材包覆保护钢结构方法探讨

新型防火板材是钢结构防火技术新的发展方向,结合钢结构防火保护技术的发展与现状,对GF防火板（1100℃级轻质无石棉硅酸钙防火板）、高温耐火胶粘剂以及用GF防火板保护钢结构的方法进行了深入的研究,并与目前大量使用的钢结构防火涂料作对比,探讨了新型防火板材在技术性能和工程施工方面的优势。     

海警部队海上反恐斗争面临的形势及对策

近年来,国际海上恐怖活动日益增多,公安海警部队海上反恐斗争形势严峻。为此,部队必须适应海上恐怖活动的特点,完善反恐工作机制,制定有效的反恐策略,切实提高海上反恐作战能力,以维护国家海洋权益及海上安全。     

钢结构防火材料应用问题及对策探讨

介绍了钢结构防火涂料的分类及特性,分析了钢结构建筑在火灾中的特点,探讨了钢结构防火涂料在技术和应用方面存在的问题,提出了钢结构建筑防火涂料施工时应注意的事项等对策。     

917低磁钢与铝合金爆炸焊接复合实验研究

采用异种金属爆炸焊接复合技术 ,研制了 91 7低磁钢与LF5、LF2 1、LF1 1等铝合金的爆炸焊接复合板 ,并对该铝—钢复合板力学性能进行了实验研究 ,对复合界面进行了金相分析 .实验结果表明 ,该铝—钢复合板复合界面物理结合良好 ,其抗剪和抗弯强度满足实船使用要求     

深圳星河世纪结构方案优选

高楼结构设计,包含结构方案选定、构件内力计算、杆件和节点构造措施等三 部分内容。工程实践经验表明,高楼结构设计能否做到安全、经济、合理,关键在于选定的结 构方案是否恰当。围绕结构方案优化这一主题,探讨了以深圳星河世纪A栋办公楼为例, 就其有关的安全、经济、合理各方面进行系统的阐述,以供同类建筑在确定结构方案时参考。     

Modeling and solution for the ship stowage planning problem of coils in the steel industry

We consider a ship stowage planning problem where steel coils with known destination ports are to be loaded onto a ship. The coils are to be stowed on the ship in rows. Due to their heavy weight and cylindrical shape, coils can be stowed in at most two levels. Different from stowage problems in previous studies, in this problem there are no fixed positions on the ship for the coils due to their different sizes. At a destination port, if a coil to be unloaded is not at a top position, those blocking it need to be shuffled. In addition, the stability of ship has to be maintained after unloading at each destination port. The objective for the stowage planning problem is to minimize a combination of ship instability throughout the entire voyage, the shuffles needed for unloading at the destination ports, and the dispersion of coils to be unloaded at the same destination port. We formulate the problem as a novel mixed integer linear programming model. Several valid inequalities are derived to help reducing solution time. A tabu search (TS) algorithm is developed for the problem with the initial solution generated using a construction heuristic. To evaluate the proposed TS algorithm, numerical experiments are carried out on problem instances of three different scales by comparing it with a model‐based decomposition heuristic, the classic TS algorithm, the particle swarm optimization algorithm, and the manual method used in practice. The results show that for small problems, the proposed algorithm can generate optimal solutions. For medium and large practical problems, the proposed algorithm outperforms other methods. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 564–581, 2015     

Optimization of process parameters of the activated tungsten inert gas welding for aspect ratio of UNS S32205 duplex stainless steel welds

The activated TIG (ATIG) welding process mainly focuses on increasing the depth of penetration and the reduction in the width of weld bead has not been paid much attention. The shape of a weld in terms of its width-to-depth ratio known as aspect ratio has a marked influence on its solidification cracking tendency. The major influencing ATIG welding parameters, such as electrode gap, travel speed, current and voltage, that aid in controlling the aspect ratio of DSS joints, must be optimized to obtain desirable aspect ratio for DSS joints. Hence in this study, the above parameters of ATIG welding for aspect ratio of ASTM/UNS S32205 DSS welds are optimized by using Taguchi orthogonal array (OA) experimental design and other statistical tools such as Analysis of Variance (ANOVA) and Pooled ANOVA techniques. The optimum process parameters are found to be 1 mm electrode gap, 130 mm/min travel speed, 140 A current and 12 V voltage. The aspect ratio and the ferrite content for the DSS joints fabricated using the optimized ATIG parameters are found to be well within the acceptable range and there is no macroscopically evident solidification cracking.