浅谈公路桥头跳车产生原因及防治措施

分析了引起桥头跳车现象的原因,并针对这些原因提出了桥头跳车的防治措施,以合理缩小造价和缩短施工工期,有效避免桥头跳车病害的产生,保证行车舒适与安全。     

工作转速下转轴碰磨振动的诊断处理

发生在某电厂1台300MW汽轮机低压转子轴承上的突发性振动．经过测试分析．诊断为工作转速下的转轴碰磨振动。通过揭低压缸检查找到了转轴碰磨振动的原因．并进行了初步分析和处理。     

Electrochemical analysis of zincate treatments for Al and Al alloy films

Electrochemical behavior of Al and Al alloy films in zincate solution was investigated to elucidate the effect of the zincate pretreatment for electroless NiP deposition, which is used for under bump metallization for LSI interconnects. The immersion potential for AlCu and AlSiCu, immediately reached to constant, which was almost equal potential to zinc reference electrode. The corrosion current for the AlCu and AlSiCu films was larger than that of the Al and AlSi films in the zincate solution. It was also confirmed that the deposited Zn at the surface of AlCu and AlSiCu films possessed smaller grain size and larger amount of nucleation, resulted in the formation of flat NiP films.     

反求工程中基于属性邻接图的凸块特征提取

反求工程（RE）中组合特征提取有利于提高建模精度及捕捉原始设计意图,但目前对于组合特征的研究还不够深入。为了从点云数据中直接提取凸块类组合特征,提出了一种反求工程中基于属性邻接图的凸块特征提取方法。首先使用基于属性邻接图的方法识别出凸块特征;接着提取凸块特征基本参数并判断识别出凸块特征的类型。实例结果表明,该方法能直接、高效地从点云数据中提取出不同类型凸块特征。     

UBM凸点互连结构信号完整性分析

建立了凸点下金属层(under bump metallization,UBM)和凸点互连结构仿真分析模型,基于HFSS软件对其高频条件下的信号完整性进行了研究.得到了UBM凸点互连结构表面电场强度分布,分析了UBM各层厚度及不同材料组合变化对UBM凸点互连结构信号完整性的影响.结果表明,不同信号频率下电场强度在凸点及UBM各层表面分布不均匀,越接近UBM顶端电场强度越大;随信号频率的提高,UBM凸点互连结构的回波损耗增大而插入损耗减小;随镍层厚度、铜层厚度和钛层厚度的增加插入损耗减小;采用Ti-Wu-Au组合UBM凸点互连结构的信号完整性最好,Ti-Cu-Ni组合次之,而Cr-Ni-Au组合最差.     

长壁孤岛工作面冲击失稳能量释放激增机制研究

煤矿开采中跳采形成的孤岛工作面由于容易产生应力集中,来压强度高,极容易发生冲击地压。基于唐山矿孤岛工作面的地质条件和周期来压步距的监测结果,通过数值分析的方法,研究孤岛工作面煤岩体能量释放的动态特征,揭示工作面前方能量释放激增机制,对比普通工作面和孤岛工作面能量场的区别,介绍冲击地压预警防治措施。数值模拟结果显示,长壁孤岛工作面回采时随着直接顶的随采随冒,采空区悬空面积的不断增大,使得老顶积聚大量的弹性能。若老顶发生周期性垮落,弹性能将瞬间释放,此时工作面和顺槽巷道极易冲击失稳。由研究结果可知,孤岛工作面周期来压时顶底板和煤层的能量激增可做为判断冲击失稳的前兆信息之一。因此,微震监测等手段可以根据此结论预测潜在的矿山动力灾害。针对老顶周期性断裂时积聚能量的突然释放规律,运用强制放顶、超前卸压孔、开切卸压槽和卸压爆破、煤层注水等技术可以提前释放煤层内积聚的弹性能,达到良好的冲击地压防治效果。     

波箔径向空气轴承起飞转速试验研究

基于微小型涡喷发动机超高速转子系统的需要,建立了波箔径向空气轴承试验台。对一系列不同结构参数的波箔径向空气轴承进行试验研究,提出了一种起飞转速的测定方法,总结轴承载荷、波箔凸起宽度、平箔厚度对起飞转速的影响,明确了起飞转速与停车接触转速之间的关系。     

大型建筑施工设备防碰撞预警程序的开发研究

文章结合建筑施工设备防碰撞预警的现实需要, 以施工设备的定位、数据的采集及施工设备的运动预判为基础,对施工设备预警程序的开发做了一定的研究。     

断层冲击地压发生机制及声发射特性

文中研究了断层冲击地压的发生机制,讨论了影响断层冲击地压发生的因素,研究了岩石不连续面破坏过程中的声发射规律,提出了采用声发射率预报断层冲击地压的可行性。     

2D-ball simulations on stiffness influences for coal bump

Coal bump is a dynamic process, thus it is necessary to reveal the process validly. 2D-ball code is an efficient approach developed by the authors based on the basic DEM rationale proposed by Cundall. Numerical simulations show that the coal bump experiences a process of energy accumulation, sudden release of energy and energy decrease. The stiffness of coal particles has a great influence on the coal bump morphosis and particle velocity. Generally, the larger the stiffness of particles, the longer the shooting off period and the larger the bump velocity. This is in agreement with the results of laboratory experiment and in-situ studies. However, the stiffness of particles has an influence on the quantity value energy and no influence on the releasing energy pattern of the coal bump. Supported by the National Natural Science Fundation of China (50534080, 50674063); Taishan Scholar Engineering Construction Fund of Shandong Province of China(J06N04)