基于dsPIC的转差频率矢量控制在电梯控制中的应用

介绍了一款结合单片机控制特点和数字信号处理器（DSP）高速运算优点的新型芯片——dsPIC30F6010。阐述了异步电动机转差频率矢量控制策略，给出了dsPIC30F6010在电梯变频调速系统中的应用实例，并对系统进行了仿真。     

Oxidation kinetics and high temperature in-situ observation of the oxidation behaviour of NbSi_2 at 1023 K

Pest oxidation has been known for a long time in refractory transition-metal disilicides such as NbSi2 and MoSi2[1―4]. However, the origin of pesting reaction of these materials is still under debate. Although the pesting phenomenon in NbSi2 has been reported in several works[5―7], a direct study of the mechanism is scarce at the moment. Compared to NbSi2, pesting in MoSi2 has received relatively extensive attention. Mckamey et al.[8] showed fragmentation near 773K occurred easily in as…     

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.     

滑模施工技术在仓筒结构中的应用

结合工程实例,介绍了仓中仓库壁滑模施工中的滑升装置及组装、滑升程序,以及在施工过程中混凝土的控制措施.     

棒形悬垂复合绝缘子芯棒脆断的原因及预防对策

通过对500kV棒形复合绝缘子高压端芯棒脆断事故发生原因的分析,指出其主要原因为绝缘子串电压分布严重不均匀及均压环设计、安装不规范而引起导线端电场畸变,加速了硅橡胶护套的电蚀穿孔所致.提出了将原下垂式线夹更换为上扛式防电晕线夹,作导线挂点“八”字型改造,在复合绝缘子导线侧加挂玻璃绝缘子;采用非标准长度的复合绝缘子与玻璃绝缘子组合成串等对策,以改善复合绝缘子的电场分布,降低导线端所承受的电压,消除畸变电场,预防芯棒脆断.实践表明,改进效果良好.     

Choking Phenomena of Gas‐Powder Flows at Sonic Velocity

Choking phenomena of gas‐powder flows in a horizontal constant cross‐section duct are experimentally studied using three kinds of powders: Al₂O₃, hollow Al₂O₃ (H‐alumina) and Al, with different physical properties such as densities, specific heat capacities and thermal conductivities. The relationship between the mass flowrate and inlet stagnant pressures is analysed and the apparent sonic velocity (ASV) of gas‐powder flows is defined. The influences of physical properties of powders on the ASV are obtained by the comparison between the experimental results of different powders. Two characteristic parameters, the effective specific heat capacity (ESHC) of solid phase and the effective isentropic exponent (EIE) of the mixture, are defined to describe the choking phenomena. The ESHC is not only measured through experiment but also calculated by numerical method. The calculated results are well consistent with the measured ones. As a preliminary application test for choking phenomena ‐ in order to uniform the pulverized coal injection (PCI) into a blast furnace ‐, a model PCI system with two branch pipes was set up and tests were carried out to verify the choking effect. The test results show that, during choking, the PC flow rates in the branch pipes can be well equalized no matter how much the downstream conditions differ from each other.     

TiC/Ti(C,N)/TiN复合涂层在滑移区的高温微动磨损特性

采用化学气相沉积（CVD）技术，在1Cr13不锈钢基体上制备TiC／Ti（C，N）／TiN复合涂层，研究了该涂层从室温（25℃）到400℃的微动磨损特性，并与无涂层的1Cr13不锈钢基材比较。结果表明：在滑移区．温度对1Cr13不锈钢微动磨损影响较显著；随着温度上升1Cr13不锈钢摩擦系数减少，磨损体积下降；而温度对TiC／Ti（C，N）／TiN复合涂层磨损体积影响不大．且磨损量均很小．TiC/Ti（C，N）／TiN涂层表现出比1Cr13不锈钢优异的抗微动磨损性能。但当该涂层被磨去后，产生的硬质磨屑形成磨粒磨损，反而对基体造成更大的损伤。     

小型CPL用高性能烧结毛细芯的研制

采用粉浆浇注工艺和氢气还原烧结工艺研制小型CPL用烧结镍毛细芯，通过优选粉浆液固比、添加剂的种类与数量、浆料pH值等参数制备了符合设计要求的烧结毛细芯。测试了毛细芯孔径、孔隙分布特征、孔径分布、孔隙度、渗透率等性能参数，分析了烧结气氛、温度、时间对毛细芯性能的影响。试验结果表明，研制的毛细芯孔隙度在68％以上，孔隙尺寸约4μm，渗透系数在10^-12～10^-13m^2之间。     

有关粘性棉问题探讨

探讨粘性棉在纺纱加工过程中对生产效率、断头和产品质量的影响,及解决粘性棉问题所采取的相应措施。     

关于球罐球片包装架的结构分析

球片包装架是球罐产品包装及运输过程中必需的结构件，然而在实际使用过程中，包装架系列过于安全。从而产生材料消耗较大、铁路运输成本升高等因素。用力学方法，通过对包装架进行合理的受力分析和计算，并以此为理论根据，本着安全、合理及高效的原则，可以降低包装架主体构件——承重梁(槽钢)型号，或增加包装架承重量的方式，对球片包装架构件进行重新设计，从而可以节省材料,增加效益。