Pyrex玻璃的湿法刻蚀研究

对Pyrex 7740玻璃的湿法刻蚀工艺进行了研究。实验中采用了几种不同的材料(光刻胶、Cr／Au、TiW／Au)作为刻蚀玻璃的掩膜，通过实验发现TiW／Au掩膜相对目前比较常用的Cr／Au掩膜有很多优点，如减少了玻璃的横向腐蚀，增加了深宽比，刻蚀图形边缘更加平滑等。还研究了腐蚀液成分配比对刻蚀结果的影响，发现刻蚀速率随HF浓度的增加而增加，且在HF浓度一定时，加入少量HNO3可以明显提高刻蚀速率。本文的实验结果对一些MEMS器件特别是微流体器件的制作有一定参考作用。     

基于ARM技术的服装舒适性检测系统的设计

设计一种基于嵌入式ARM处理器的便携式服装压力、温湿度检测系统。系统采用ARM9处理器S3C2410A为主控芯片,利用FlexiForce压力传感器、DHT90温湿度传感器为分布式测试元件,以SD卡作为存储介质对采集的数据进行离线保存,并借助LabVIEW开发的仪器面板将测量结果保存并以直观的形式显示出来。测试实验结果表明服装舒适性检测系统测试准确,工作可靠,可以为服装舒适性的客观评定提供科学依据。     

Picosecond dynamics of optical gain switching in vertical cavityemitting lasers

It is demonstrated that optically gain switched GaAs vertical lasers (VSELs) with short cavity lengths can generate pulses as short as 4 ps, with delays as short as 20 ps. A model of the large-signal response of VSELs to short optical input pulses is presented. The results demonstrate that the critical parameter of determining VSEL response time is the cavity length. A numerical solution to the rate equations is used to calculate the output pulsewidth and delay, given a specific cavity design and set of input conditions. Calculated results are compared to experimental data. Output pulse dependencies on input pulsewidth and power are examined for different cavity designs. The results of the calculations are used to generate design curves for future devices     

黄海平流雾对8~12 μm波段红外辐射衰减的实验研究

为了研究新一代舰载红外探测系统在海雾条件下的探测能力,以黄海海雾为实验环境,以非制冷型红外热像仪为探测器,分别在不同强度的海雾中以不同性质的红外辐射源为探测对象进行了成像实验,并结合红外辐射在海雾中的衰减模型进行了量化研究。衰减模型可分为物理模型和经验模型两大类,分别对其在不同强度海雾下的衰减曲线进行了对比分析,并根据实测结果进行了拟合分析,结果表明:在轻雾条件下,实际观测的结果几乎与物理模型一致;在较浓海雾条件下,以经验模型计算的结果与观测结果相差较小;而在特浓海雾条件下,以经验模型计算的结果较接近于实际观测。     

CDMA网络规划的线性建模方法

该文提出了CDMA网络规划的线性建模方法。该方法用线性方程组对 CDMA系统进行建模,并可用迭代的方法求解,该文同时给出了模型的仿真结果,仿真结果表明,该方法具有较高的准确性,完全可以用于对实际网络的规划,同时,该方法便于用计算机实现,可以作为规划软件的算法模型。     

Radiation from an open-ended waveguide with beam equalizer--A spectral domain analysis

A septum and an impedance matching post are used as a beam equalizer in an open-ended waveguide feed for reflectors used in satellite communications systems. The performance of this design over a frequency band is evaluated using a spectral domain approach. The computed radiation patterns in theE- andH-planes, as well as the results for the impedance match are presented.     

卫星信道下低速扩频信号的快速同步

提出一种适合于卫星信道下低速扩频信号的快速同步方案。在高速时钟的驱动下,利用抽头数远小于扩频码长的匹配滤波器实现扩频信号的快速捕获;扩频码同步后先利用部分相关值对大载波频差进行初步估计,估计范围可接近符号率;然后再利用全相关值对剩余小频差进行精确的估计;最后利用锁相环实现载波的跟踪。计算结果和仿真结果表明,该方案是切实可行的。     

基于激光诱导荧光光谱的塑料分类鉴别

为了实现 废弃塑料的快速分类识别,利用激光诱导荧光(LIF)光谱技术对不同材质塑料进行分类和鉴 别,通过搭建LIF测量系统,使用发射波长为266nm的ND:YAG固体激 光器作为光源,Ocean Maya2000 Pro光谱仪 作为荧光检测装置,探测了9种塑料荧光光谱。对获得的荧光光谱进行均值化处理和平滑处 理,消除数据 误差、减低光谱噪声。然后根据欧式距离对9种塑料样品光谱特征值进行聚类分析,结果显 示,同元素构成 的塑料聚类效果较好,其中5种塑料只含C、H元素为一类,剩余4种多元素塑料归为另一 大类,此外荧 光峰数目、位置、强度可作为塑料种类鉴定的依据。实验结果表明,LIF光谱技术可应用于识 别不同塑料样品的材质,为塑料制品的快速识别分类提供一种新的方法。     

C-band field effect transistor amplifiers

The basic elements used are Schottky-barrier field-effect transistors. These transistors, called MESFETs for metal-semiconductor field-effect transistors, have exhibited stable power gain to frequencies as high as 12 GHz. The results of this program thus far are given, including the circuit analysis, design parameters, and test results on a C-band demonstration amplifier.     

任意曲线形状介质栅漏波天线辐射特性的改进微扰法分析

本文是对作者前一工作(1990)的补充和发展,文中用改进的微扰法分析了任意曲线形状介质栅漏波天线的辐射特性。所得数据和用场匹配方法得到的精确值进行了比较。结果表明,本文方法在保持相同精度的情况下,极大地简化了求解过程;并据此系统地研究了周期槽形状对介质栅漏波天线辐射特性的影响。文中给出的曲线可供设计介质栅天线时参考。     

Hadamard扩谱及CDMA的研究

在MATLAB平台上,对直接序列扩频系统进行仿真分析.系统采用Hadamard序列作为扩频码,对系统在平坦衰落和瑞利衰落信道环境下的误码率进行分析,讨论了扩频、解扩过程.此外,还仿真比较了不同用户数和不同扩频码的系统,为分析设计直扩系统提供依据.仿真结果表明,本实验系统可在SNR为-1.6dB的传输条件下得到10-3量级的误码率,Hadamard序列可用作扩频序列,系统可用作检验各种正交码组的正交性.     

Design and Optimization of ESPAR Antennas via Impedance Measurements and a Genetic Algorithm [Antenna Designer's Notebook]

A method for the design of electronically steerable passive array radiator (ESPAR) antennas is proposed herein, based on impedance-matrix measurements and a genetic algorithm. The proposed technique is best suited for cases where commercial elements are used as building blocks for ESPAR development, since in such cases the conventional numerically based techniques used in the literature may not be applicable. An emulated ESPAR design and respective results are presented. They demonstrate the applicability and performance of the proposed technique, as well as its consistency with results derived from a commercially available electromagnetic simulator.     

Loss minimization in scalar-controlled induction motor drives withsearch controllers

Loss minimization in scalar-controlled induction motor drives (IMD) with search controllers (SC) is investigated. The problems arising when the input power is used as the controlled variable are described. It is proved that better results are achieved if the stator current is used as the controlled variable     

A Comparison of the Focusing Properties of a Fresnel Zone Plate With a Doubly-Hyperbolic Lens for Application in a Free-Space, Focused-Beam Measurement System

A Fresnel zone plate is designed to perform the function of a doubly-hyperbolic lens. The focusing characteristics of the zone plate and the lens are compared using both measured data and body-of-revolution finite-difference time-domain simulations. The results from this comparison are used to evaluate the use of zone plates as focusing elements in a free-space, focused-beam measurement system. A set of two zone plates is used to perform measurements of the material properties of a dielectric sheet, and the results are compared to the results from a standard system which uses two doubly-hyperbolic lenses.      

Bulk silicon technology for complementary MESFETs

A technology for fabrication of complementary silicon MESFETs on bulk silicon substrates has been developed. The technology is similar to CMOS technology, and utilises n-silicon substrates. P-wells are used for the n-channel devices. Device isolation was achieved by trench etching. The silicides of Er and Pt were used as gate Schottky contacts. P- and n-channel characteristics are presented together with subthreshold behaviour and preliminary results regarding radiation hardness. Also, results from two-dimensional simulations of the devices are presented.<>     

Modeling and Analyses of Vias in Multilayered Boards with the Aid of Look-Up Tables

Vias passing through multilayered boards are studied by using microwave network theory and antenna theory. By means of suitable electromagnetic simulations, the propagation parameters of vias are computed accurately. The results are then organized into a form of a look-up table so that some interpolation algorithm could be used. Compared with the direct numerical simulation, this kind of process could save much time and space resource, and its results are fairly good as shown in this paper. It has already been used in a CAD software.     

激光能量及重复频率对土壤等离子体特性的影响

利用波长为1064 nm的Nd∶YAG脉冲激光器作光源,以高分辨率、宽光谱段的中阶梯光栅光谱仪和增强型电荷耦合器件(ICCD)作为谱线分离与探测器件,测量并分析了激光能量及重复频率对土壤中铅元素激光诱导击穿光谱特性的影响。实验结果表明,随着激光脉冲能量(在25~105 mJ范围内)增加,谱线强度呈线性增加,随后谱线强度随脉冲能量(105~165 mJ)的变化呈非线性关系。信背比随激光能量的增加而增大,但激光能量超过60 mJ后基本上不变。激光重复频率为1 Hz时,谱线强度最大,而谱线强度的相对标准偏差则在重复频率为7 Hz时最小。     

基于短时谱分析的语音增强改进算法

介绍了基本的语音增强短时谱分析算法的原理.基于经典的谱减算法进行改进,引入了先验信噪比估计,以及时间回归平均法对噪声进行更新,以及一系列后处理改进方法,提高了降噪效果.在保持语音可懂度的基础上,增强了噪声衰减量.主、客观实验结果表明,针对汽车噪声一类的平稳噪声,算法效果出色;而对于街道、人声一类非稳态噪声,该算法性能优...     

反射式液晶器件振幅调制特性的研究

研究了反射式液晶器件(RLCOS)的振幅调制特性.采用2×2的琼斯矩阵计算仿真,从理论上分析了它的振幅调制特性.实验采用He Ne激光为光源,将反射式液晶器件显示器作为液晶空间光调制器,用计算机和相关的电路系统驱动控制,并用CCD采样数据,测试了1024×768反射式液晶器件显示器的振幅调制特性.与未改形光束剖面相比,在特定的入射、出射偏振光配制下,可以用反射式液晶器件显示器来做振幅调制器.     

Radiation losses of tapered dielectric waveguides: a finitedifference analysis with ridge waveguide applications

The finite-difference third-order simplified wave equation method is used to study the radiation losses of optical waveguides with step (abrupt) and parabolic tapers, including the radiation losses of the tapered ridge waveguides used as electro-optic phase modulators for tuning the frequencies of infrared lasers. The radiation losses of the parabolic taper given by Burns et al. is found to be under 5%. The results of a step taper are compared with Marcuse's; and found to be in good agreement. The numerical results are also compared with those from the coupled wave equations used by Sporloder and Unger