不同风速下侧向散射激光雷达的回波信号分析

对不同风速条件下,CCD侧向散射激光雷达的回波信号进行了分析.根据Mie散射原理及侧向散射激光雷达工作原理,确定了大气气溶胶浓度与激光雷达侧向散射光强的相关性;进一步考虑气溶胶浓度与风速的关联,利用实验装置获取了激光雷达侧向散射光强与风速的关系,分析了不同风速条件下侧向散射激光雷达的回波信号.在轴流风机以及自然风两种条件下进行对比实验发现,当风速范围在1~4.5 m/s时,侧向散射光强随风速的增加而增加;当风速范围在4.5~6.0 m/s时,光强随风速的增加较少.对实验结果归一化处理,得到风速范围在1~4.5 m/s时,风速每增加1 m/s,侧向散射光强在轴流风机及自然风的实验条件下分别增加了3.7%和3.9%;风速范围在4.5~6.0 m/s时,风速每增加1 m/s,侧向散射光强分别减少了3.1%和3.8%,在自然风况的各个风向上都基本符合这一变化趋势.     

基于同伦方法反演非饱和土中镉离子传输参数

依据实验室土柱实验结果，引入同伦方法对镉离子在不同非饱和土样中的传输参数进行了反演计算，得到了相应的反演结果．     

Perturbation finite volume method for convective-diffusion integral equation

A perturbation finite volume (PFV) method for the convective-diffusion integral equation is developed in this paper. The PFV scheme is an upwind and mixed scheme using any higher-order interpolation and second-order integration approximations, with the least nodes similar to the standard three-point schemes, that is, the number of the nodes needed is equal to unity plus the face-number of the control volume. For instance, in the two-dimensional (2-D) case, only four nodes for the triangle grids and five nodes for the Cartesian grids are utilized, respectively. The PFV scheme is applied on a number of 1-D linear and nonlinear problems, 2-D and 3-D flow model equations. Comparing with other standard three-point schemes, the PFV scheme has much smaller numerical diffusion than the first-order upwind scheme (UDS). Its numerical accuracies are also higher than the second-order central scheme (CDS), the power-law scheme (PLS) and QUICK scheme. The project supported by the National Natural Science Foundation of China (10272106, 10372106)     

化学气相沉积金刚石薄膜成核机理研究

本文综述了在化学气相沉积（Ｃｈｅｍｉｃａｌ Ｖａｐｏｒ Ｄｅｐｏｓｉｔｉｏｎ,ＣＶＤ）金刚石薄膜过程中非金刚石衬底表面金刚石成核机理研究进展。主要讨论了衬底表面缺陷诱导金刚石成核模型,指出最大原子团的存在决定了金刚石成核是否能够在衬底表面发生;分析了金刚石在非金刚石衬底成核时的过渡层问题,提出了过渡层存在机理;对于在等离子体ＣＶＤ中的偏压增强金刚石成核效应,提出的负偏压离子流增强成核模型和正偏压电     

等离子体CVD金刚石薄膜衬底正偏压增强成核效应机理研究

衬底正偏压增强成核效应是最近等离子体ＣＶＤ金刚石薄膜中光滑衬底表面金刚石的成核研究发现的，它对于增强和控制金刚石在非金刚石衬底光滑表面的成核行为具有重要的意义。基于已经得到的实验结果。本文分析了衬底正偏压作用于成核过程的机理，提出了这种效应的电子流密度模型，并且给出了正偏压增强效应与沉积参数的关系，描述了正偏压处于过渡和饱和区时的成核状态，合理地解释了所谓“正偏压阻止成核”现象，本模型的结果与已经     

A KINETIC MODEL FOR THE INITIAL GROWTH OF DIAMOND FILMS

Based on a surface reaction mechanism for diamond deposition from the gas phase, a kinetic model is developed to describe diamond nucleation sites and the initial stage of diamond growth in chemical vapor deposition. The timein dependent solutions to the rate equations, which describe the steady-state growth of diamond films, is obtained analytically for the case of small ratio of car bon flux to atomic hydrogen flux. The time-dependent solutions obtained by nume rical methods for large ratio of carbon to atomic hydrogen flux describe the nucleation and initial gorwth stage of diamond films. This model suggests some general predictions for diamond nucleation and growth and can be used to explain several important experimental phenomena observed by others.     

室温下用脉冲激光沉积E-BN薄膜

 在利用等离子体增强脉冲激光沉积系统沉积立方氮化硼（cBN）薄膜时，发现了氮化硼（BN）材料的E-BN相，并利用扫描电镜和红外吸收光谱及X射线衍射技术对薄膜样品进行了分析，得到了制备较高质量E-BN薄膜的一些热力学参数及时间参数，验证了现有的E-BN结构的形成理论。     

CVD金刚石薄膜生长中的偏压增强成核效应

实现金刚石薄膜的异质外延是目前ＣＶＤ金刚石薄膜制研究的主要奋斗目标，而直流负偏压增强金刚石成核法被认为是达到这一目标的有效途径。文章简要评述了微波等离子体ＣＶＤ制备金刚石薄膜中的直流负偏压增强成核法，以及由此而发展的直流正偏压增强成核法和叠加交流成分的直流负偏压增强成核法，介绍了它们在异质外延金刚石薄膜中的应用。     

Mo衬底生长金刚石薄膜表面晶形研究

 用HFCVD方法在Mo衬底上进行了金刚石薄膜生长研究，观察到在不同的反应压强条件下，金刚石薄膜晶粒的三种形貌，并且讨论了反应条件对晶粒形貌的影响以及菜花状大晶粒的构成机理。     

热丝CVD方法生长金刚石薄膜中石墨成份控制

 在用热丝CVD方法生长金刚石薄膜中，研究了生长条件对制备膜中石墨和非晶碳成份的影响，发现较高的碳源浓度或较低的衬底温度会使制备膜中非金刚石相碳成份增加。