一种单相开关电源输入电流谐波抑制方法的研究

根据2000年制订的新IEC1000-3-2电磁兼容标准规定,对单相开关电源全桥整流器加LC滤波器的简单经济无源功率因数校正电路进行了新的分析和设计.建立无量纲归化电路进行仿真分析,结果表明,适当的滤波电感值设计可以取得高功率因数和满足新电磁兼容标准A类和D类电流谐波限制规定,尤其是在300W以下A类电力电子设备可以采用小而经济LC滤波器.分析和计算结果通过计算机仿真和实验验证.     

用8098单片机HSI,HSO组成数字触发器

介绍采用８０９８单片机中的高速输入器ＨＳＩ和高速输出器ＨＳＯ组成晶闸管三相桥式全控整流电路的数字触发器。直接由并行口输出６个互差６０°的双窄脉冲，利用８０９８单片机内部Ａ／Ｄ直接采样移相控制信号，从而构成了一个仅有一片８０９８单片机的开环控制系统。若将数字控制器的输出作为移相控制信号，则可方便地构成仅用一片单片机的闭环数字控制系统     

投入产出模型在部门间产品价格变动中的应用

利用投入产出模型建立价格变动方程，并由此给出一个或若干部门产品价格、固定资产折旧及新创造价值变动，对其他部门产品价格产生影响的计算公式     

模型参数分布未知的贝叶斯预测

本文介绍了线性贝叶斯方法，并将其应用于贝叶斯动态线性模型，得到了模型参数分布未知情况下模型的修正递推及预测算法，从而拓宽了贝叶斯动态线性模型的适用范围。     

The effect of a dielectric cover on the input impedance of rectangular microstrip antennas

The effect of the thickness and relative permittivity of a dielectric cover on a rectangular microstrip antenna is analyzed. The method is based upon the integral equation formulation. The input impedance of the rectangular microstrip antenna is calculated as a function of the thickness and relative permittivity of a dielectric cover, after solving the integral equations by Galerkin's method. Computed results for the input impedance are presented and some are compared with the available experimental data. It is shown from the computed results that the resonant frequency and input impedance are sensitive to variations of the cover parameters. Because of the limited bandwidth presented by the rectangular microstrip antenna, the effect of the dielectric cover has to be carefully taken into account in the design of the antenna. Fan Zhibo: born in March 1963, Ph. D. Current research interest is in microwave and antennas     

用VB将UCDOS6.0的普通码输入法移到中文Windows95中

论述从ＵＣＤＯＳ６．０的输入法中提取普通码码表文件、经过运行相应的转换程序转换成中文Ｗｉｎｄｏｗｓ９５输入法的码表文件，再将其编译成中文ｗｉｎｄｏｗｓ９５的普通码汉字输入法，进一步扩大了ｗｉｎｄｏｗｓ９５的功能。     

乳状液的热力学特征及其它

本文较详尽地介绍了乳状液的稳定性理论、乳状液类型的测定、变型、去乳化等基本特征。     

浅谈英语教学中目的语非言语表达知识的导入

非言语表达是语言构成中的重要部分,它的得体运用,可以提高交际效果。鉴于外语教学中重视目的语中的言语表达忽视非言语表达的现状,本文探讨了非言语表达在外语学习中的重要意义,并提出一些实际可行的手段。     

基于观测器的时滞依赖鲁棒无源控制

研究一类带有参数不确定性和时变时滞的不确定线性系统的鲁棒无源控制问题。针对标称系统,利用线性矩阵不等式给出其时滞依赖无源性条件;讨论当系统的系数矩阵出现参数不确定时,存在基于观测器的控制器使得闭环系统是强鲁棒稳定且严格无源的时滞依赖性充分条件。构造出期望的观测器和控制器。数值算例说明结论的有效性。     

Feedforward and feedback optimal control for linear time-varying systems with persistent disturbances

1 .INTRODUCTIONIn nature ,there are various external disturbancesaffecting the performances of systems . Many con-trol problemsinvolve designing a controller capableof stabilizing a given linear system while mini mi-zing the worst-case response to some additive dis-turbances . This problemis relevant to disturbancerejection and cancellation. One application area ofinterest is flight control through wind shear ,where disturbances arise from a modal for windshear based on harmonic oscillati…