激光相位成像雷达的研究

利用无合作目标漫反射激光相位测距的原理,对关键单元技术进行分析和设计,研制成一种用于自主式车辆视觉导引的激光相位成像雷达的原理样机.     

提高微波功率源性能的一种新型控制系统

本控制系统用于抑制大功率速调管输出微波功率宏脉冲平顶波纹,改善电子直线加速器输出束流的品质.控制方法采用微分线性逼近和矩阵算法对系统的输入和输出进行分析,求出代表系统响应的传输矩阵,从而将复杂的激励一响应计算转化为简单的代数运算.实验结果显示出宏脉冲平项波纹得到了有效抑制,说明采用自适应前馈控制来获得平坦的宏脉冲平顶是切实可行的.     

Crystal structure and magnetic ordering of RNi Si compounds

The element distributions and the magnetic ordering behaviour of compounds RNi₁₀Si₂ (R = Tb, Dy, Ho, Er, Tm) have been studied by neutron powder diffraction down to temperatures of 1.6 K. The compounds crystallize in an ordered variant of the ThMn₁₂ structure type in the tetragonal space group P4/nmm. An ordered 1:1 distribution of Ni and Si on sites 4d and 4e, respectively, corresponds to a modulation vector [0, 0, 1] with respect to the space group I4/mmm of the ThMn₁₂ structure. TbNi₁₀Si₂ orders antiferromagnetically below T _N = 4.5 K with a magnetic propagation vector of [0, 0, 1/2]. The magnetic Tb moments, 8.97(2) /Tb atom at 1.6 K, are aligned along the c-axis. The Ni sites in TbNi₁₀Si₂ do not carry any ordered magnetic moments. The compounds with R = Dy, Ho, Er, and Tm are paramagnetic down to 1.6 K and 3.0 K, respectively. Received 10 July 2002 / Received in final form 12 September 2002 Published online 29 October 2002     

高功率激光驱动器中小尺度自聚焦和噪声模型

 建立了一套线性的近似分析方法，研究高功率激光驱动器中强激光传输的小尺度自聚焦效应和相位噪声对光束传输和光束质量的影响，给出了系统噪声强度、B积分值与光束近场调制对比度之间的定量关系。研究表明,为保证输出光束质量，即近场调制对比度小于给定值，系统内的噪声强度必须符合一定的谱分布。     

AN ALTERNATIVE SPECIFICATION FOR MODELING GROUNDWATER DYNAMICS

This research extends previous work with dynamic models to manage groundwater quality by using the consumptive nitrate use rate instead of the nitrate application rate. The analysis indicates that misspecification results in overestimation of economic benefits, and supra-optimum nitrogen fertilizer application rates and groundwater nitrate stocks at a steady state.     

类铜离子的电子碰撞参数及其规律

用准相对论扭曲波方法系统地计算了Ｂａ、Ｎｄ、Ｇｄ、Ｙｂ、Ａｕ、Ｐｂ类铜离子组态能级之间的电子碰撞激发强度Ω（ｎｌ－ｎｌ），３≤ｎ≤７，４≤ｎ≤７，同时给出了高能极限的碰撞强度和外推到阈值的碰撞强度，用最小二乘样条方法拟合了全能域碰撞强度及热平均速率系数。对于一个激发过程，用１０个参数可以得到碰撞电子在任意能量下的碰撞强度以及任意温度下的速率系数。     

The epitaxial growth of gaas using alkylarsine: Part 2. molecular orbital calculation

Semi-empirical molecular orbital calculations were carried out for the compounds (C₂H₅)₃As, (C₂H₅)₃Ga and RAsH₂ (R = C₂H₅, i-C₃H₇, i-C₄H₉, and t-C₄H₉) by using the CNDO/2-U program, and their capability of β-elimination reaction is compared on the basis of the torsion energy to the transition state, electrostatic interactions and orbital overlapping between the central atom and the β-hydrogen, and bond order of the metal-carbon, and carbon-hydrogen bond. In the comparison of (C₂H₅)₃As with (C₂H₅)₃Ga, we found that the β-elimination of (C₂H₅)₃As could hardly be expected to take place in the thermal decomposition. The capability of β-elimination would be smaller in C₂H₅AsH₂ than that in (C₂H₅)₃As. Moreover when the ethyl group is replaced by a t-butyl group in RAsH₂, the β-elimination reaction appears to become more difficult and a large possibility for a radical process is suggested.     

Reflection of Surface Plasmon Polaritons by a Corner Reflector of Negative Index Materials

A novel type of corner reflector for the reflection of surface plasmon polariton (SPP) is proposed. The reflector consists of two layers of compensatory media whose permittivity and permeability take opposite signs to that of the corresponding layer of the SP waveguide. By rigorously solving Maxwell's equations, the reflected SPP is proved to exist. The transverse wave vector of the reflected SPP is always antiparallel to that of the incident SPP and no phase retardation is introduced.     

Analysis method of the effect of fabrication errors on a planar waveguide demultiplexer

The impact of fabrication errors on a planar waveguide demultiplexer is analyzed based on an analytical method. The explicit expression of the transfer function taking into account phase and amplitude errors is presented in order to analyze the loss and crosstalk of the demultiplexer caused by fabrication errors. A basic requirement for the demultiplexer with a certain crosstalk criterion can be easily obtained. Using an etched diffraction grating demultiplexer as an example, it is shown that the analytical results have a good agreement with results from a numerical method.