Dynamic model building and simulation for mechanical main body of lunar lander

Focused on the dynamics problems of a lunar lander during landing process, the whole process was analysed in detail, and the linear elastic model of the moon soil was established by means of experiments-analogic method. Combining the way of elastic impact with the way of velocity replacement, the dynamics model of damping free vibration dynamics model with 3-degree of freedom(DOF) for lunar lander is obtained according to the vibration mechanics elementary theory. Based on Lagrange equations and the energy principle, the damping free vibration differential equations for the lunar lander with 3-DOF are derived and the equations are solved in simulation ways by means of ADAMS software. The conclusions obtained can be used for the design and manufacture of lunar lander.     

坚持科学发展观,努力创建和谐公司

第一点我想要说的是，发展是硬道理。综合性工程咨询公司是在我国政治经济体制改革的大潮中应运而生的，是在计划经济向市场经济过渡时期，为适应政府投资决策科学化民主化而成立的，经过二十年的风风雨雨，她已经成长为活跃于从中央到地方的一支很有影响的中介力量，为推动我国投资决策的科学化民主化作出了人所共知的贡献。但随着我国投资体制改革的进一步深入，各类中介机构的迅速崛起和市场竞争的日趋激烈，综合性工程咨询机构向何处去，引起同行们的关注。本人的认识是：发展是硬道理。不管遇到什么艰难险阻，只要聚精会神地谋发羼，综合性工程咨询机构就能经受住改革阵痛的考验，就会前途无限。     

Influence of ultra-fine fly ash on hydration shrinkage of cement paste

1INTRODUCTION Hydrationshrinkageisalsoknownaschemicalshrinkage[1].Thesolidvolumeincreasesafterce menthydrating,buttheabsolutevolumeofcementwatersystemreduces.Usuallythetotalamountofvolumeshrinkageofcementwatersystemis7%9%[1,2].Withthedevelopmentofthetechno logyofcementandconcrete,concretewithhighstrengthandhighperformanceisthedevelopingtendencynow.However,nowadays,comparedwithordinaryconcrete,thehydrationshrinkageofhighperformancecementconcreteincreasesobvi ouslybecauseoftheaccelerationof…     

Strain rate sensitivity of tensile properties in high Nb containing TiAl alloys

The effect of strain rate on the yield strength of high Nb containing TiAl alloy was studied. The results show that the strain rate sensitivity varies with the test temperature, and the yield strength is not sensitive to the strain rate at room temperature but significantly sensitive to the strain rate at high temperature. An increase of the strain rate or a decrease of the temperature results in an obvious change of fracture mode. It is found that the strain rate sensitivity of this alloy varying with temperature is due to the dislocation climb generated at high temperature.     

Thermoelectric properties of p-type （Bi0.15Sb0.85）2Tes-PbTe graded thermoelectric materials with different barriers

The p-type （Bi0.15Sb0.85）2Te3 and PbTe are typical thermoelectric materials used for low and middle temperature range and functional graded materials （FGM） is an inevitable way to widen the working temperature range. Here two segments graded thermoelectric materials （GTM） consisting of （Bi0.15Sb0.85）2Te3, PbTe and different barriers were fabricated by the common hot pressure method. Metals Fe, Mg and Ni were used as barriers between the two segments. The diffusion of different barriers between the barriers and bases were analyzed by electron microprobe analysis （EMA）. The phase and crystal structures were determined by X-ray diffraction analysis （XRD）. The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction. The results show that the compositional diffusion occurs when there is no barrier at the interface of the two segments, and the diffusion of Pb is most obvious; as the barrier material, the diffusion of metals Fe, Mg and Ni between different bases is not very obvious, and the thermoelectric properties of GTM is much better than that of the original segment.     

锂离子电池正极材料LiMn2O4的制备技术及其研究进展

尖晶石LiMn2O4是最有希望替代LiCoO2的新一代锂离子电池的正极材料。本文对锂离子电池的工作原理和3种正极材料作了简要介绍。综述了近年来LiMn2O4制备技术的研究进展,并对其今后的发展进行了展望。     

Evaluating Acceleration Ability of Electrons of SiO_2 and ZnS in ZnS∶Er Electroluminescence

SinceCoeyandSun[1]discoveredtheinterstitial compoundSm2Fe17Nx,ithasattractedmanyresearch ers′attention.Asakindofpermanentmagneticmate rial,Sm2Fe17Nxexhibitsfairlyhighsaturationmagneti zation(1.54T)[2],highanisotropyfield(14T)under roomtemperatureandhighC…     

变刚度弓网系统主动控制研究

以变刚度时变弓网系统模型为研究对象,应用最优控制策略,分别采用控制力作用于框架和弓头两种方式,对弓网间接触力进行主动控制,仿真结果表明,采用受电弓主动控制能够抑制弓网间接触力的波动,提高受流质量,当主动控制力直接作用于框架时控制效果更好。     

长期贮存后导爆管的性能检测与分析

塑料导爆管的长期贮存试验对于导爆管的实际使用性能具有重要的指导意义,同时对于导爆管产品有关标准的完善能提供重要的依据.文章针对贮存时间超过24年的一组导爆管产品做了外观、传爆可靠性、拉伸强度等性能检测,并对检测结果与现有的普通导爆管进行了分析和对比,证明了导爆管在正常条件下长期贮存后安全稳定,性能可靠.     

理论模型在高质量、无缺陷铸坯生产中的应用

尽管连续铸钢技术已经在全世界广泛、成功地应用，然而通过现存所选择的工艺和设计参数来生产高质量产品还有一些障碍。近年来，通过冶金工作者的不断努力，取得了一些突破性成就。