一种C波段宽带二维扫描固态有源相控阵天线设计与实现

基于机载合成孔径雷达系统的具体应用,给出一种C波段宽带二维扫描固态有源相控阵天线的设计与实现方案. 该天线辐射阵面采用双层矩形微带贴片,由宽带偶极子激励. 通过增加金属隔墙和金属接地螺钉的加载来降低天线单元间互耦,实现了宽带二维相控扫描. 测试结果表明,辐射单元阵中驻波带宽(VSWR<1.6) 达到800 MHz(相对带宽约15%).     

量热和热分析在生物大分子体系研究中的应用

讨论了差示扫描量热法(DSC)和等温滴定量热法(ITC)用于生物大分子体系研究所得到的一些实验结果。内容包括了沙冬青抗冻蛋白热滞活性的测定、胶束解体浓度的确定二个方面内容。所有研究结果都给出了有关生物大分子变化的明确信息和确切结论。     

Parallel Spectral-Domain Optical Coherence Tomography for Non-Scattering Object Imaging

The parallel spectral-domain optical coherence tomography(PSDOCT) is described for high-speed optical coherence tomography(OCT) without lateral scanning. In this setup, the self-elimination of auto-correlation(AC) interference algorithm was used for eradicating the AC interference and ghost images. However, when performed in free space OCT, this algorithm still generated a weak DC component. The algorithm was improved by adding the background intensity part to compensate for the mutual interference between object and reference arms. The results demonstrate that the DC component can be eradicated. Compared with conventional OCT and complex Fourier-domain optical coherence tomography, the advantages of PSDOCT with the improved algorithm in free space are that it has no moving parts to generate consecutive phase shift, the structure of the object can be reconstructed immediately and automatically, and the speed is approximately 16 times faster than those of the other two in the same case.     

光泵磁共振实验评述

对光磁共振实验的主要内容进行了系统的评述，包括实验中水平方向的磁场、光抽运信号的变化、光泵磁共振信号观察时光抽运信号混杂出现和谐波共振的情况、gF因数的测量方法，以及用光磁共振和光抽运信号测地磁场的方法。     

自制扫描隧道显微镜探针尖的比较研究

探针对扫描隧道显微镜成像起至关重要的作用。本文分别对电化学腐蚀法自制的钨丝探针和剪切法制得的铂铱探针进行扫描光栅图像比较分析。结果表明,相比铂铱探针,钨丝探针虽然制备繁琐,反应条件不易控制,但是尖锐轴对称形的钨丝探针扫描样品形貌更加细微,用作扫描隧道显微镜探针时扫描成像质量高。该研究为扫描隧道显微镜探针的选用提供了依据。     

车载卫星天线扫描与跟踪系统设计

首先从车载天线接收系统总体设计方案进行阐述,给出了相应的系统框图,进而在论述中规划了车栽卫星天线接收主控系统的硬件设计模块．接着研究分析了此次硬件设计中使用到的接口：SPI、TWI、USART,完成了MEGA64主控模块的硬件设计,并给出系统板的原理图,最后,给出了车载卫星天线扫描跟踪算法设计．     

Eponyms,Inventions and Devisers: A Contest

ABSTRACT

In the summer of 1998, the University of North Carolina at Chapel Hill conducted a pilot project for electronic reserves using Contec North America's ‘C3’ e-reserve system. This paper discusses how the pilot project was implemented, including equipment required for the system, types of materials placed on reserve, and problems encountered and solved. It also examines the areas that will determine the future of e-reserves at UNC-CH, copyright management, web access, and the incorporation of multi-media and online articles.     

Kent State University's Electronic Reserves Experience

ABSTRACT

In late 1996, Kent State University Libraries began to research electronic reserves software in order to conduct a pilot project. The software chosen was ERes 2.0, developed at Santa Clara University by Philip Kesten and Slaven Zivkovic. This article describes how and why ERes was chosen and how the system was adapted for use at Kent State University. The integration with the OPAC and full-text databases, as well as the pitfalls encountered during the pilot project is detailed. Also described is the experience of learning to scan print documents efficiently.     

激光扫描器扫描成像问题分析

激光扫描器广泛应用于激光电视、在线检验和条码识别等领域。激光扫描器的方式多采用转镜-振镜方式,但由于转镜-振镜扫描系统存在一些固有的缺陷,会产生扫描非线性和非对称性,引起显示图象的畸变。本文将以40面转镜-振镜系统为例,即采用40面体转镜作为反射镜来获得行扫描,来分析多面体转镜系统的扫描成像问题。     

Managers' Information Seeking Behavior--A Study of Environmental Scanning

首先介绍企业经理人信息查寻行为--环境扫描的概念及其作用,继而从扫描关注的信息焦点、信息源的选择使用、扫描的模式、扫描的影响因素等方面对环境扫描理论进行详细的论述,并提出环境扫描的信息查寻行为模型。