遮掩式低回波金属支架的设计

本文推出了一种具有固定遮掩屏的低ＲＣＳ金属支架系统；介绍了其主要特点及设计方法；计算了该支架了多种数学模型的散射截面分布；试验研究了优化支架模型的散射特性。本文的计算及试验结果对于设计制做产用回波金属目标支架具有重要的参照价值。     

Development of Bi(Pb)-2223/Ag pancake-shaped and solenoidal coils

High temperature superconducting (HTSC) multifilamentary (MT) Bi(Pb)-2223/Ag tapes with reproducible critical current density of between 15000 and 20000 A/cm² at 77 K in self field have been achieved using the standard flat-rolling method as the intermediate deformation between sintering periods. Long lengths of Bi(Pb)-2223/Ag MT tapes up to 43 m prepared by the conventional method of powder-in-tube (PIT) have been successfully produced on a laboratory scale. Several coils have been fabricated from sections of the long length tape, using the co-wound wind-and-react (W&R) procedure for the pancake-shaped and the singly-wound W&R as well as R&W procedure for the solenoidal coils. A novel W&R solenoidal coil (reaching ~973 ampere-turns) wound on an alumina ceramic tube generates a DC field of ~19 mT at 77 K and has been fabricated together with five pancake-shaped coils, each generating an average of ~5 mT at 77 K. These are destined for magnet construction with a possible combined calculated field of ~0.04 T at 77 K (with liquid nitrogen as a coolant)     

Growth of CeO_2, Y_2O_3 Buffer Layers for YBCO Coated Conductor

~~Growth of CeO_2, Y_2O_3 Buffer Layers for YBCO Coated Conductor     

用步进电机实现连续变焦距光学镜头的变焦控制

根据望远镜的工作原理，对变焦距光学镜头的变焦运动进行了定性分析，并且根据理想光学系统的物像关系式推导出该镜头运动镜组的运动方程。该连续变焦控制的实验装置包括步进电机，电机驱动器以及控制平台，其控制程序用VisualC 编写。实验表明，该方法能方便地实现连续变焦距光学镜头的变焦控制。     

浅谈移动通信基站天线系统设计

对基站天线的基本原理、天线选型、天线参数设置、天线安装等方面进行了描述，对天线下倾角、分集距离等进行了重点讨论。     

基于片上DC-DC的CMOS光接收机前置放大器

利用CSMC 0.6μm CMOS工艺,设计了基于片上DC-DC转换器的光接收机前置放大器。电路采用可调跨阻放大器与片上DC-DC结构,有效地克服了单端跨阻放大器易受电源波动的干扰,并解决了高灵敏度与低失真相互矛盾的问题。模拟结果表明,输入动态范围为83 dB(峰-峰值=0.2μA~3 mA),等效输入电流噪声为1.2 pA/Hz(155 MHz),可稳定工作在155 Mb/s速率上;在5 V电源电压下,功耗为95 mW。     

Time-domain measurements with the Hewlett-Packard network analyzerHP 8510 using the matrix pencil method

The generalized pencil of function (GPOF) method, also known as the matrix pencil method, is used to improve the resolution of HP 8510B network analyzer data in the time domain. This method provides for much higher resolution than the Fourier techniques. A comparison of the two methods is given for the example of the Beatty standard. The examples show that a parametric technique such as the GPOF can provide accurate and reliable results with a high degree of resolution even when the fast Fourier transform (FFT)-based technique fails     

基础下早期人防工程处理的实践与探索

地下早期人防工程的处理是当前城市建设中经常遇到的问题。鲁南商城工程地上六层 ,地下一层 ,场区地下有一组早期人防工程 ,距地面 7 0m ,距拟建工程基底不足 2 0m ,影响了工程建设。设计人员通过对早期人防工程的加固处理 ,并在拟建工程设计中运用补偿基础理论 ,消除了地下早期人防工程的不良影响 ,使工程建设顺利进行。该工程实例对同类问题的解决具有实际意义。     

一种高速浮点加法器的设计实现

浮点加法器是协处理器的核心运算部件，是实现浮点指令各种运算的基础，其设计优化是提高浮点运算速度和精度的关键途径。文章从浮点加法器算法和电路实现的角度给出设计方法，并且提出动态与静态结合设计进位链的方案以及前导O预测面积与速度的折衷方法。动态与静态结合设计进位链的方法有效地降低了功耗，提高了速度，改善了性能。目前已经嵌入协处理器的设计中，并且流片测试成功。     

Gamma-Ray-Induced Multi-Effect on Properties of Chalcogenide Glasses

Gamma-ray irradiations induced various alterations in sulfur- and selenium-based chalcogenide glasses. The absorbed dose was in the range of 0.01–3.6 MGy. The glasses exhibit prominent sensitivity to γ-ray irradiation, characterized by changes in some of the physical properties of the glasses, e.g., optical transmission, optical band gap, density, and thermal expansion coefficient. The effects on glass structure and microscopic morphology were also studied by Raman spectra and scanning electron microscopic observations.