Numerical Modeling of Dendrite Growth in AI Alloys

Dendritic grains are the most often observed microstructure in metals and alloys. In the past decade, more and more attention has been paid to the modeling and simulation of dendritic microstructures.This paper describes a modified diffusion-limited aggregation model to simulate the complex shape of the dendrite grains during metal solidification. The fractal model was used to simulate equiaxed dendrite growth.The fractal dimensions of simulated AI alloy structures range from 1,63-1.88 which compares well with the experimentally-measured fractal dimension of 1.85; therefore, the model accurately predicts not only the dendritic structure morphology, but also the fractal dimension of the dendrite structure formed during solidification,     

运用稀浆封层修复水泥混凝土路面

稀浆封层是近年来国内外普遍应用的一种低投资、高效率的道路维修养护技术，稀浆封层在路面结构体系中，只能作为表面保护层和磨耗层及防水层，而不起承重性的结构作用。因此，不管是沥青混凝土路面还是水泥混凝土路面，均可应用稀浆封层进行表面处置。     

A New Self-assembly Metal CMG Discriminator by Multi-exposure LiGA Like Process and Sacrificial Layer Process

The counter-meshing gears （CMG） discriminator is a mechanically coded lock, which is used to prevent the occurrence of High Consequence Events. This paper advanced a new kind of self-assembly metal CMG discriminator based on multi-exposure LiGA like process and sacrificial layer process. The new CMG discriminator has the following characters except low cost： 1） it has only discrimination teeth sections; 2） the thickness of each gear layer exceeds one hundred micrometers; 3） it is axially driven by a separate dectronic magnetic micromotor directly; 4） its CMG is made of metal and is batch fabricated in the assembled state; 5） it is prevented from rotating in the opposite direction by pawl/ratchet wheel mechanism; 6） it has simpler structure. This device has better strength and reliability in abnormal environment compared to the existing surface micro machining （SMM） discriminator.     

经典居商住楼结构转换层施工

结构转换层施工是框架剪力墙结构施工的难点。本文通过经典居商住楼监理，对结构转换层的施工规律进行了研究。     

直线法结合有限差分法计算多层多导体传输线电容和电感矩阵

本文首次将直线法和有限差分法结合起来,用于计算多层介质多导体传输线的电容和电感矩阵.通过在纯介质区域使用直线法,导体所在区域使用有限差分法分别进行求解,充分发挥两种方法各自的优越性.数值结果表明:方法是有效的,且计算时间与介质层的厚度无关.     

百年教育管理思想回顾

20世纪以来教育管理理论主要有四种。这些理论的产生和发展与当时世界经济的发展有着直接的关系。教育管理的理论在不断解决自身问题的同时，也不断创造新的理论，进一步激发人们对教育管理的深层思考，进而推动教育管理理论的不断发展。     

对金属切削毛刺的试验分析

讨论了在切削加工中塑流层的形成及切削毛刺的生成机理，在采用直角自由刨削加工方式中。结合前角γ０、进给量ｆ及切削速度ν等因素的变化，通过试验的方法对毛刺的影响进行了探讨。