In situ study on dendrite growth of metallic alloy by a synchrotron radiation imaging technology

This study was trying to observe the real-time dendrite growth of Sn-Bi and Sn-Pb binary alloys by a synchrotron radiation imaging technology.The imaging system includes an intense and high brightness synchrotron radiation source,a high-resolution and fast-readout charge coupled device camera,an alloy sample and a Bridgman solidification system.The imaging experiments were done at Beijing Synchrotron Radiation Facility with an updated synchrotron radiation imaging technique,diffraction-enhanced imaging,whic...     

Modeling radiative properties of nanoscale patterned wafers

Temperature nonuniformity in rapid thermal processing of wafers is a critical problem facing the semiconductor industry. One cause of the problem is the nonuniform absorption of thermal radiation in patterned wafers where the optical properties vary across the wafer surface. This paper presents a parametric study of the radiative properties of patterned wafers, considering the effect of temperature, wavelength, and polarization. The finite-difference time-domain (FDTD) method is employed to examine the effe...     

Experimental study on high viscosity fluid micro-droplet jetting system

Fluid dispensing is a method by which fluid materials(such as epoxy,adhesive,and encapsulant) are delivered in a controlled manner in electronics packaging.Fluid jetting,derived from inkjet technology,is a noncontact,data-driven fluid dispensing technology.But ideal fluid materials for packaging are usually high viscous,which is difficult to realize by traditional inkjet technology.In this paper,a mechanical micro-droplet jetting system for high viscosity fluid was proposed.It consists of dispensing valve,m...     

Dimensional synthesis of a 3-DOF parallel manipulator based on dimensionally homogeneous Jacobian matrix

A study of dimensional synthesis of a 3-DOF parallel manipulator with coupling of translation and rotation is carried out.The architecture of the manipulator is composed of a moving platform attached to a fixed base through three identical PRS(prismatic-revolute-spherical) serial limbs,whose unique topology leads to the physical unit inconsistency of the conventional Jacobian matrix and the emergence of the parasitic motion.Then this paper introduces a kinetostatic performance index of the manipulator based...     

Fold-Hopf bifurcation in a simplified four-neuron BAM (bidirectional associative memory) neural network with two delays

The bidirectional associative memory (BAM) neural network with four neurons and two delays is considered in the present paper.A linear stability analysis for the trivial equilibrium is firstly employed to provide a possible critical point at which a zero and a pair of pure imaginary eigenvalues occur in the corresponding characteristic equation.A fold-Hopf bifurcation is proved to happen at this critical point by the nonlinear analysis.The coupling strength and the delay are considered as bifurcation parame...     

Experimental study of CT test on the failure of acrylate spray-applied waterproof layer in the groundwater environment

In this study the computerized tomography (CT) was first used to quantitatively analyze the failure of acrylate spray-applied waterproof membrane in the groundwater environment. The results of the CT tests show that it is feasible to use the CT to quantitatively analyze the failure of the waterproof membrane and the CT method has the advantages of speediness and accuracy that can eliminate the fussy operation process in routine tests. The main conclusions summarized from the study are as follows. First, the...     

基于TMS320F240DSP的开关型磁阻电动机调速控制技术

开关型词组电动机调速系统（Switched Reluctance Drive,简称SRD）是80年代中期发展起来的新型交流调速系统，它融新的电动机结构——开关型磁阻电动机（简称SR电动机）与现代电力电子技术，控制技术为一体，兼有异步电动机变频调速系统和直流电动机调速系统的优点，已成为当代电气传动的热门课题之一。     

基于MSM7512B的远程无线通信系统的设计与实现

介绍了一种利用单片FSK Modem芯片实现单片机与PC机的远程无线通信技术，分析了系统组成及接口设计，并介绍了通信软件的设计。     

闪光灯泵浦Nd3+:GGG激光特性研究

用闪光灯泵浦掺钕钆镓石榴石(Nd^3 ：GGG)激光晶体，研究了脉冲宽度0．5ms、1ms、1．5ms和2ms的放电泵浦下激光输出，实验获得了1．92J的最大激光能量．     

氮化硅/石墨激光合金化涂层的组织结构与性能研究

为获得金属表面特别是高副接触金属表面含自润滑特性且具有高硬度耐磨特性的功能材料 ,研究了 45 # 钢表面激光合金化氮化硅 /石墨复合涂层的工艺方法、组织特征、界面形态及其形成机制 ,利用光学显微镜、扫描电镜和X射线能谱对所形成合金化层的元素分布和含量进行了分析 ,并对试样硬度进行了测定。结果表明 ,合金化层中元素Fe ,Co ,Si,C分布均匀 ;C含量达到了 15 6 9%,大部分以石墨的形式存在 ,具有一定的自润滑性能 ;但在形成合金化层的温度条件下 ,氮化硅分解严重 ;合金化层硬度提高的主要原因是Si Fe ,Co Fe固溶体的强化作用及高碳马氏体的生成和高硬度碳化物的存在。