The effect of skin characteristics on the environmental behavior of die cast AZ91 magnesium alloy

The skin characteristics of die cast AZ91 magnesium alloys and their consequent environmental behavior were evaluated in correlation with die cast wall thickness. The metallurgical examination of the skins was carried out using scanning electron microscopy (SEM), SPX-surface analyses with ESCALAB 250 apparatus, and X-ray diffraction analysis. The corrosion behavior of the skins was evaluated by immersion tests and by potentiodynamic polarization measurements in 3.5% NaCl solution saturated with Mg (OH)₂ at room temperature. The results show that the corrosion resistance of die cast specimens with relatively greater thickness was improved compared to the corrosion resistance of thin wall specimens. This was explained in light of the obtained skin characteristics, mainly in terms of aluminum content, β phase (Mg₁₇Al₁₂) quantity and morphology, and level of porosity.     

现场总线技术在选矿自动控制系统中的应用

在冶金行业选矿干选工艺的自动控制中,将PROFIBUS现场总线技术应用于现场控制级和过程监控级,实现PC与PLC间、PLC与PLC间以及CPU与远程I/O间的总线通信.该控制系统已成功应用于武钢集团程潮选矿厂干选工艺的自动化改造中,运行可靠,效益显著.     

光纤传感器在土木工程中的应用与发展综述

介绍土木工程领域中各类光纤传感器,对其工作原理、优缺点以及发展前景进行评述。     

Preparation of inorganic–organic pillared montmorillonite using ultrasonic treatment

Montmorillonite (Mt) is a clay mineral with expandable layer structure. Mesoporous pillared montmorillonite can be prepared by introducing gallery templates, such as simple metal cations, quaternary ammonium cations, long chain amines, and hydroxyed inorganic metal ions. In this paper, inorganic–organic pillared montmorillonite intercalated by aluminium and alkyl ammonium chloridize (HDTMA–Cl) was successfully prepared by ultrasonic treatment, and the physicochemical properties of the materials were systematically characterized by XRD, FT-IR, SEM and TEM techniques. The d₀₀₁ basal spacings and microstructures of Mt–Al–HDTMA were characterized by XRD. The function group, crystal surface morphology, structural and chemical analysis of Mt–Al–HDTMA were measured by FT-IR, SEM, TEM and EDX. The results indicated that ultrasonic method might accelerate the diffusion of the intercalating species, which enhanced the textural properties and the morphologies. The results also suggested that aluminium and HDTMA–Cl reagent entered the interlayer of Mt, and that the crystal structure of the final Mt was preserved.     

基于物联网的人性化智能家居系统研究

针对智能家居系统特点及需求,建立基于物联网的人性化智能家居系统架构模型,研发中转器、壁式智能控制终端、基于Android的智能控制终端,最后搭建整个基于物联网的人性化智能家居系统,进行远程控制及现场控制测试。该系统性能稳定、性价比高、舒适安全、实用性及可操作性强,可个性化情景模式控制,易于安装、维护及扩展。     

变批量车间调度文化进化算法研究及应用

针对JIT环境下柔性生产的要求,多品种小批量生产使车间调度规划更加困难,许多生产调度优化问题属于NP-hard问题,其求解通常采用智能启发式算法。文化进化算法基于文化算法、文化进化思想及超群进化思想,通过上层文化空间的经验知识指导下层个体进化搜索的方向及步长,通过模拟人类社会文化进化的机制实现文化空间的进化与更新,最后将算法应用到变批量Flowshop问题的求解,用Matlab编程仿真测试,结果表明用此算法进行批量分割,解决生产调度优化问题是可行的,而且其搜索性能优于AGA算法。     

无线以太网通信系统在风电场的应用

目前风电场内的监控系统是通过在风电机组间铺设光缆,机舱内安装工业以太网交换机的方式将机组运行数据上传到SCADA上位机来实现的。为了适应海上风电场的建设,文章介绍一种能在风电机组内进行快速布置、灵活组网的无线局域网技术的应用,并重点探讨了机组偏航导致天线间相对位置变化带来的天线方向图的不均匀问题和风电机组桨叶运转对无线信号的动态阻挡形成衍射效应导致的多径衰落问题及解决途径。     

Comparing the Slack-Variable Mixture Model With Other Alternatives

There have been many linear regression models proposed to analyze mixture experiments including the Scheffé model, the slack-variable model, and the Kronecker model. The use of the slack-variable model is somewhat controversial within the mixture experiment research community. However, in situations that the slack-variable ingredient is used to fill in the formulation and the remaining ingredients have constraints such that they can be chosen independently of one another, the slack-variable model is extremely popular by practitioners mainly due to the ease of interpretation. In this article, we advocate that for some mixture experiments the slack-variable model has appealing properties including numerical stability and better prediction accuracy when model-term selection is performed. We also explain how the effects of the slack-variable model components should be interpreted and how easy it is for practitioners to understand the components effects. We also investigate how to choose the slack-variable component, what transformation should be used to reduce collinearity, and under what circumstances the slack-variable model should be preferred. Both simulation and practical examples are provided to support the conclusions.     

钢铝压-胶复合连接接头力学行为与失效机理研究

在钢铝压印连接界面之间加入胶粘剂,能有效提高接头性能,但接头的力学行为与失效机理非常复杂.以双相高强钢板DP590和铝合金板6061-T6为连接材料,对钢铝压-胶复合连接接头的力学行为和失效机理进行了有限元模拟和试验研究.基于ABAQUS有限元分析软件,采用GTN(Gurson tvergaard needleman)...     

飞机APU涡轮导向叶片高温防护涂层失效模式分析

利用扫描电镜(SEM)、能谱分析仪(EDS)等分析了国内某型在役APU涡轮导向叶片的结构特征与热防护机理,研究了叶片失效件中高温防护涂层的厚度变化与失效模式。结果表明:飞机APU导向叶片中存在渗铝涂层+MCrAlY涂层与单一渗铝涂层2种不同的涂层结构;APU导向叶片失效件的MCrAlY涂层厚度从叶片尾缘—叶盆—前缘区域呈先增大后减小的趋势;受叶片构型影响,叶片尾缘区域涂层的氧化程度较严重,而叶盆区域越靠近前缘的位置涂层氧化损伤程度越低,但叶片前缘区域由于受CMAS腐蚀与高温氧化的耦合作用使得该区域涂层损伤最为严重。