Finite element analysis on shape deformation of the macro-structure region during hot-rolling process for gear steel FAS3420H and its modification

The rectangular macro-segregation region in the core of hot-rolled steel bar has a great influence on the heat treatment distortion of an automotive gear steel FAS3420H. In order to understand the distortion process of the segregation region during hot-rolling process, a finite element (FE) analysis of the whole hot-rolling process was carried out by software DEFORM-3D, and a constructed constitutive model was embedded into DEFORM-3D to describe the deformation process. The results show there is an inhomogeneous strain distribution at the cross-section of hot-rolled round bar, which results in uneven distortion of the segregation region in different directions. A square segregation region, which can reduce inhomogeneous distortion of gear in the subsequent heat treatment, is obtained after being rolled by simulation calculation verified through experiment.     

边缘建筑的学校图书馆设计

着知识的“神化”,图书馆的功能从“知识的传播”转向“知识的交流”,并最终异化为一个“仪式性”的产生。本文以此为切入点,对哈尔滨工程大学图书馆的设计过程进行了介绍,方案围绕“仪式性场所”的构建,试图创造一个“神圣”“世俗”与“标志性”混合体,以回应知识-权力关系在今天作为“科学”的话语形式。     

改善60 t EAF-LF-VD-CC流程冶炼齿轮钢FAS3420H洁净度的研究

以抚顺特钢一炼钢厂的生产数据为实践依据,以改善汽车齿轮钢FAS3420H的洁净度为目的。使用扫描电镜分析水口结瘤物和棒材中氧化物夹杂的化学成分,确定了通过减少钢中的B类夹杂物来解决水口结瘤问题的方向。通过优化电弧炉供氧曲线降低钢水氧化性、优化精炼炉渣流动性和碱度提高夹杂物吸附能力等措施,解决了连铸过程水口结瘤问题,同时达到棒材的氧含量平均值为9.2×10^-6,B类夹杂物B细不高于1.0级、B粗不高于0.5级的控制水平。     

An efficient multilevel solution scheme for large scale non-linear systems

We present a new approach for the fast, efficient solution of large systems of non-linear equations arising from the finite element discretization. The proposed non-linear solver builds on the advantages of the popular methods of solution that are currently being employed, while eliminating most of their undesirable features. It combines the well-known BFGS method with the FAS version of the multigrid method, introduced by Brandt,¹ to form a fast, efficient solution method for non-linear problems. We present numerical performance studies that are indicative of the convergence properties as well as the stability of the new method.     

Petri网融合蚁群算法的柔性装配系统调度

为解决柔性装配系统的调度问题,采用分层时延Petri网模型与蚁群优化算法相结合,将柔性装配系统分解成诸多个装配体,每个装配体再分解成多个柔性装配单元,对装配单元分别建模并用蚁群算法对装配方案遍历优化,最后确定装配系统的时延Petri网模型.该方法融合了Petri网和蚁群算法各自的优点,较好地解决了柔性装配系统中的装配建模和装配任务的分配优化问题.实验证明该研究可行有效.     

A heterogeneous space–time full approximation storage multilevel method for molecular dynamics simulations

A heterogeneous space–time full approximation storage (HFAS) multilevel formulation for molecular dynamics simulations is developed. The method consists of a waveform Newton smoothing that produces initial space–time iterates and a coarse model correction. The formulation is coined as heterogeneous since it permits different interatomic potentials to be applied at different physical scales. This results in a flexible framework for physics coupling. Time integration is performed in windows using the implicit Newmark predictor–corrector method that permits larger time integration steps than the explicit method. The size of the time steps is governed by accuracy rather than by stability considerations of the algorithm. We study three different variants of the method: the Picard iteration, constrained dynamics and force splitting. Numerical examples show that FAS based on force splitting provides significant time savings compared to standard explicit methods and alternative implicit space–time schemes. Parallel studies of the Picard iteration on harmonic problems illustrate the time parallelization effect that leads to a superior parallel performance compared to explicit methods. Copyright © 2007 John Wiley & Sons, Ltd.     

谈FAS抗地铁电磁干扰能力和措施

通过对地铁工程中如何在强电磁环境中保证消防设备的正常使用及避免产生新的电磁干扰进行了总结分析,并介绍了可以有效保证FAS系统正常运转的各种措施,以指导实践。     

关于高层建筑消防设计审核若干问题的思考

随着我国经济的快速发展和城市化进程的突飞猛进,各类高层建筑特别是超高层建筑纷纷涌现,对高层建筑的防火、控火、灭火提出了更高要求,如何合理配置建筑物的消防设施和满足安全要求,设计审核是一重要环节。本文将从事消防设计审核工作中遇到的若干问题和相关思考撰写成文,供同行交流参考。     

慈竹化机浆漂白性能研究

对慈竹单段漂白和多段组合漂白性能进行了系统研究,提出了慈竹化机浆漂白至71%以上白度的工艺。研究结果表明,H2O2总用量10%,慈竹化机浆经单段H2O2漂白,白度只能达到64.7%~65.0%;两段H2O2漂白具有较高的漂白效率,漂白浆白度达到66.6%~67.1%;总漂剂用量为12%的三段组合漂白,结束段分别使用H2O2、FAS和Na2S2O4不同漂白方式,FAS漂白效率最优,白度达到72.9%;其次是H2O2漂白,白度为71.9%;以FAS为结束段的漂白,与本色慈竹化机浆相比,抗张指数、耐破指数和撕裂指数分别提高200%~300%、250%~300%和250%~270%。采用碱性Na2SO3化学预浸渍,两段H2O2漂白加一段FAS漂白的三段组合漂白,慈竹化机浆可漂白至71%以上的白度。     

溶胶凝胶法制备TiO2薄膜及其润湿性研究

采用溶胶凝胶法,于金属基片上构筑TiO2薄膜,通过修饰1H,1H,2H,2H-十七氟癸基三甲氧基硅烷后,薄膜显示疏水性.对TiO2凝胶的热稳定性进行分析,结果显示,在450℃及以上的温度进行热处理,有机成分可被全部除掉.对所制备薄膜的物相组成和显微结构进行表征,并考察热处理温度对薄膜表面形貌及润湿性能的影响,结果表明,热处理温度为550℃时,疏水性能最好,达到超疏水性.