基于数学建模要求下先进的提拉法控制系统研制

提出了在开发一种先进的直拉法晶体生长控制系统中占据重要地位的设备及工艺特征的下位机模型;分析所采集到的实验数据,揭示出控制中的重要问题,由此开发了一种新的控制结构;该模型是建立在常规控制结构和提出新的控制结构性能对比的基础上。     

热电制冷红外探测器氧化铍瓷冷板和散热板导热系数的测量

氧化铍恣导热系数是表征热电制冷红外探测器半导体制冷器部件冷板和散热板导热能力的关键参数。本文论述了氧化瓷导热系数的测量原理和方法，推导了计算公式，分析了影响测量的关键因素并提出了相应措施，对样品制作和装配工艺提出了要求。最后，给出了样品实例测并得出结论。     

Gallium Nitride Room Temperature α Particle Detectors

Gallium Nitride （GaN） room temperature α particle detectors are fabricated and characterized, whose device structure is Schottky diode. The current-voltage （I- V） measurements reveal that the reverse breakdown voltage of the detectors is more than 200 V owing to the consummate fabrication processes, and that the Schottky barrier and ideal factor of the detectors are 0.64 eV and 1.02, respectively, calculated from the thermionic transmission model. ^241Am α particles pulse height spectra from the GaN detectors biased at -8 V is obviously one Gauss peak located at channel 44 with the full width at half maximum （FWHM） of 15.87 in channel. One of the main reasons for the relatively wider FWHM is that the air between the detectors and isotope could widen the spectrum.     

电子系统封装器件的传热研究

开发了一个电子系统封装(SIP)典型器件的传热模型,用数值方法模拟了器件的热传递过程和温度分布状况,探讨了各种设计参数和物性参数对温度场的影响。计算结果表明:当t = 1 400 s,以LCP为基板时SIP器件传热过程达到稳定态,基板导热系数和对流换热系数是影响器件散热速率的关键参数,此外还计算了对于不同的环境对流换热系数和不同基板材料,不使芯片产生热失效所允许的输入功率耗散密度。这为研究高密度电子封装器件的热特性,进一步改善器件的热性能提供了理论依据。     

均匀自由流动的非牛顿流体中连续表面上的磁流体动力学流动和热传递

分析在平行自由流动的非牛顿黏弹性导电流体中,连续平展表面移动时的稳态流和热传递特性,该流动处于横向均匀磁场作用下.以二阶流体构建它的本构方程,得到了速度分布和温度断面图的数值结果.讨论了诸如黏弹性参数、磁场参数和Prandtl数等不同物理参数对诸种动量和热传递特性的影响,并给出相关图示.     

Piecewise analysis of oblique vibro-impacting systems

A great number of studies have shown the complex nonlinear dynamics of mechanical systems with repeated normal impacts. An oblique frictional impact introduces even more complicated dynamics such as stick-slip motions to those systems. Hence, the dynamics of oblique vibro-impacting systems with possible sliding motion is an open problem. Based on a hybrid analysis of vibro-impact dynamics, kinematics and complementary conditions, a piecewise analysis method is developed in the paper to describe the sliding motion during an oblique impact. Thereby, a parametrically excited planar pendulum between two parallel rigid walls is studied as an illustrative example. The example, together with the corresponding numerical results, shows that the sliding impacts occur in such a system with a set of properly selected parameters. The project supported by the National Natural Science Foundation of China (59905010) and by the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education, China     

脉冲激光加热薄膜微尺度热传递研究进展

短脉冲激光显微微加工因其具有制作高精度微结构的能力和其在现代微制作技术中的应用,微尺度薄膜热传递的研究受到极大关注,近年来对薄膜结构高频加热的研究迅猛发展。本文对十年来薄膜微尺度热传递的相关研究进展做了简要评述。     

Modelling of Phase Change Heat Transfer System for Micro-channel and Chaos Simulation

The dynamic properties for the micro-channel phase change heat transfer system are studied by theoretical method combined with experiment. Liquid-vapour interface dynamic systems are obtained by introducing disjoining pressure produced by three phase molecular interactions and Lie algebra analysis. Experiments for 0.6 mm×2 mm rectangular micro-channel are carried out to obtain the pressure time serials. Power spectrum density analysis for these serials shows that the system is in chaotic state if the frequency is above 7.39 Hz. The result indicates that the high heat transfer performance of the micro channel phase change system may relate to the characteristics of chaos, The chaos attractor is drawn by the simulation of the obtained differential dynamic system under the conditions of our experiment.     

微系统封装热问题探讨

电子机械系统微型化就是把不同功能的各种元器件封装到紧密空间, 目的在于分析有关封装设计负载下降的方案. 采用计算机程序配置发生器生成系统的热传递路径的几何构造和平面基板上热分布作为样本的方法,把这些构造的温度解决方案压缩进入快速估计公式中,使封装设计能够自由地进行相关的热传递分析. 通过涉及到几何学方面复杂的传热路径的系统热传递分析,快速完成每个设计改变. 结果表明系统微型化热设计,就是系统构造和整个向周围环境热损耗之间的耦合,就是热通过自然对流和辐射,从系统外壳上的一个区域向周围扩散. 最后得出结论,外壳材料热传导性跨越的参数领域,以及系统的性能长度为系统级热传递领域,对系统的构造敏感.性能长度对塑料封装系统而言约为1cm,对陶瓷及合金封装约为3~10cm,在铜或铝金属包层系统为10~40 cm.     

热传递对异面腔四频差动激光陀螺温度漂移补偿的影响

为了减小四频激光陀螺零漂的温度敏感性,对数学补偿模型和安装结构热设计进行了研究。通过高低温实验研究了四频激光陀螺零漂与温度的关系。第一次采用普通铜支架将四频激光陀螺固定在屏蔽盒内,由于两放电支路的温度变化不对称,温度变化率是数学补偿模型的显著项。第二次设计了专用铜支架,使两放电支路的温度对称地变化,因而温度变化率在数学补偿模型中的重要性大大降低。改进支架之后,补偿后的零漂残差从0.018 Hz降低到0.01 Hz,即便采用温度多项式补偿模型也能达到0.012 Hz。这些结果表明:在设计四频激光陀螺系统时,安装结构热设计能够提高数学模型补偿的效果,温度补偿是提高四频激光陀螺的精度的有效方法,在-40~60℃温度范围内补偿后的百秒标准差达到0.013/（（）h）。