A microwave Gaussian-beam launcher with an active aperture-blockageto control the spot-size of the beam

A method of controlling the spot-size of a focused microwave Gaussian-beam using an active aperture-blockage is described. The Gaussian-beam launcher consists of an open-ended scalar-horn with a dielectric hyperhemisphere at its aperture. Also included is an AgI-pellet at the aperture-center with a provision to heat it with an external dc source. The scalar-horn plus the dielectric lens launch a Gaussian-beam; and, the AgI pellet when heated, becomes a superionic conductor offering an aperture-blockage. This results in a variation of the spot-size of the emergent-beam. Theoretical results and experimental data are furnished and compared     

微电子电路PC机辅助教育系统

文章介绍法中两国合作开发的微电子电路计算机辅助教育系统中的两部分，重点陈述其中的辅助测试虚拟仪器和专用实验芯片，期望对电子测试领域的教育工作者和科技工作者有所启发。     

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     

主动阻尼控制中的扩展加速度输出反馈法

正位置反馈(PPF)是一种能够显著提高结构模态阻尼的控制策略，但是这种策略在原理和应用中具有一定的局限性。本文在指出了传统的PPF控制器的优缺点基础上，提出一种扩展的加速度输出反馈控制方法AOEF，同时给出了最优AOEF控制器的设计计算方法。仿真计算和实验表明，在传感器／作动器同相的情况下，采用这种控制器的闭环系统具有无条件的稳定性，在非同相的情况下也能达到优良的控制性能。     

FBOLES—outline of a frequency-based on-line expert system approach for fault diagnoses in nuclear power plants

The basic concept of a novel frequency-based on-line expert system (FBOLES) approach for on-line fault diagnoses in nuclear power plants has been presented previously. This paper reports further progress, and includes how to express the uncertainties of expert opinion in knowledge-bases and propagate then in inferences, and how to deal with imperfect knowledge-bases. It also describes the main elements of FBOLES and outlines how the system works under complex conditions including the dynamic behavior of signals during accidents, multiple failures, and on-line changes of plant operation mode. Its ability to diagnose root causes of accidents has been tested using the main steam and feedwater condensate systems of a full-scale, three-loop, 950 MW nuclear power plant simulated by the Tsinghua simulator. So far the results seem good.     

^125I,^131I诱发小鼠精子畸形发生率比较

本文选用 ICR 雄性小鼠,经腹腔分别注射不同剂量的~(125)I 及~(131)I,观察并比较它们对小鼠精子畸形发生率的影响及染毒后睾丸中放射性活度的变化。实验结果表明:(1)~(125)I 染毒后4—5周,0、185、370和555 kBq 各组精子畸形发生率分别为9.00‰、9.57‰、11.6‰及13.9‰;~(131)I 染毒后4—5周,上述各组精子畸形发生率分别为8.50‰、12.5‰、14.7‰和15.5‰;在相同注入量下,~(125)I 与~(131)I 诱发小鼠精子畸形发生率的差异各组均不显著(X~2检验,p>0.05)。(2)~(125)I、~(131)I 染毒后2h 至7天内,两者在睾丸中的放射性活度及变化规律相似,即在染毒后2h 达最高值,每克睾丸中~(125)I 和~(131)I 的放射性活度分别占初始注入量(370 kBq)的0.72％和0.50％,然后迅速下降,至一周时,仅分别占初始注入量的0.035％和0.011％。     

中小企业创业资源的形成机制研究

创业资源是创业的基础,创业过程的规律性和市场配置资源的基础作用影响和决定中小企业创业资源的内在功能和形成方式。对中小企业资源的形成机制进行了分析探讨,并分析了它们之间的内在关系。     

坐标旋转法的收敛性,误差估计及扩展

本文通过推广正规序列的定义,得到一个不等式,由此证明了统一计算初等函数数值的坐标旋转法的收敛性,作了误差估计,并拓广了所计算的函数范围,成为快速计算所有初等函数的统一算法．     

压缩弯曲小半径中频弯管工艺的研究

在分析了感应加热小半径弯管形变机理的基础上，提出了压缩弯曲的成型工艺，研制出了小半径中频弯管设备，并进行了大量的工艺实验和实验研究，取得了满意的结果。     

A circuit model for the class E resonant DC-DC converter regulatedat a fixed switching frequency

An averaging circuit model is developed for the class E resonant DC-DC converter regulated at a fixed switching frequency. The regulation is achieved by use of an auxiliary switch. The model is obtained based on the circuit analysis using the Fourier series expansion. Steady-state and small-signal dynamic analysis is presented, which reveals that the DC output is well controlled by the control angle of the auxiliary switch and that there exists a right-half-plane zero in the control-to-output transfer function. The analysis results are verified by the experiments