从时频分布到连续子波变换

本文从时频分布的物理概念出发，首先指出了各种时频分析方法的内在联系和差别，然后着重从连续子波变换在信号分析中的物理意义来讨论它的数学表示和特有性质，并和短时傅里叶变换作了比较。接着对连续子波变换在时间尺度平面上的离散化的概念作了扼要描述。最后，基于文中叙述的物理概念，对子波变换的应用和进展作了简要评述。     

IP技术在SOC中的地位及应用

本文主要介绍了IP技术的概念，并且对其在SOC的地位作了详细的说明，最后对IP在SOC中的应用作了简要的介绍。     

影响无线市话来话接通率的因素

阐述了无线市话来话接通率的概念，对常见影响因素作了具体分析。     

图文电视技术简介

文章对国内外图文电视的发展状况和有关技术概念作了详细的解释。对图文电视解码器的原理，作了比较详细的分析。     

视频点播的系统分析和关键技术

介绍了视频点播的概念，分析了视频点播的系统结构，并对一些技术问题作了初步的探讨。     

视频音频非线性编辑系统技术分析

对视音频非线性编辑系统所涉及的一些概念作了一定分析，对一些技术指标，存在的问题及发展趋势作了介绍，力求使大家对视音频非线性编辑系统有一个全面正确的认识。     

激光束的相干合成技术

本文可实现激光束相干合成的一些有用的技术作了总结，对由Ｓｃｈｕｓｔｅｒ等人 掾联ＭＯＰＡ系统进行成对共线光束合成的功率定标模型作了分析，最后，对与位相控制概念有关的作了讨论。     

雷达工作灵敏度的讨论

雷达接收机接收微弱信号的能力常用临界灵敏度来定义，是十分成熟的概念。在某型号工程的研制过程中，对雷达接收处理灵敏度的使用概念上有一些新的认识，本文加以总结后，引进了雷达切线灵敏度和工作灵敏度的概念，并对相应的测试方法作了实验研究。     

可靠性仿真技术

本文简要介绍了可靠性仿真概念，基本方法和技术难点，并对其应用前景作了初步探讨。     

MPEG-21多媒体框架标准前瞻

本文介绍了MPEG－21多媒体框架标准的产生背景，目的及其构成，对于其中关键概念作了解释，并对MPEG－21的数字项作了进一步阐述，最后讲述了MPEG－21发展中必须解决的关键问题。     

高功率因素整流器技术综述

由三菱电机开发研制的MELVEC矢量控制变频调速系统的装置中，采用了具有PWM高功率因数整流的控制技术，并且使用了IGBT、GTO、IGCT等功率器件。提高了功率因数，已被广泛地应用在钢铁（冶金）行业中。本文简要说明其电路构成的原理，重点介绍和分析了高功率因数的控制技术、控制系统的设计理念，并简述了装置中高次谐波的问题。     

Voltage-source charge-pump power-factor-correction AC/DC converters

Voltage-source charge-pump power-factor-correction (VS-CPPFC) AC/DC power converters are proposed in this paper. The PFC converter using the CP concept is first derived. The unity power factor condition is derived and analyzed. The clamping technique is used to satisfy the unity power factor condition. Based on the steady-state analysis, design considerations for the CPPFC stage are discussed. A family of VS-CPPFC topologies is also presented. The proposed VS-CPPFC AC/DC power converter was implemented and tested. The experimental results show that 83.5% efficiency and 0.996 power factor can be achieved for a half-bridge CPPFC AC/DC converter with 250-W and 12-V output,     

Power factor enhancement of induction machines by means ofsolid-state excitation

A novel concept for power factor correction of induction machines is introduced that employs an auxiliary three-phase stator winding together with a pulse-width-modulated (PWM) inverter to supply excitation power to the machine. When the PWM inverter is modeled as an equivalent capacitor, it is shown that two values of capacitance will yield unity power factor at a given operating condition. The effect of machine parameters on the critical value of capacitance is examined. A control algorithm to ensure unity power factor at the terminals of the main stator windings is presented, and its satisfactory operation is verified by means of a detailed analog computer simulation     

微波无线能量传输的空间匹配理论

微波无线能量传输,即采用微波为载体形式,将能量无线传输到负载端。微波无线能量传输中效率和功率是衡量传输系统的重要指标。目前,仍然缺乏微波无线能量传输系统整体效率的设计方法。文章提出了微波无线能量传输系统的空间匹配理论,即场匹配、功率匹配和阻抗匹配。根据这一理论设计的传输系统,其传输-转换效率得到显著提高。     

A new UPS topology employing a PFC boost rectifier cascadedhigh-frequency tri-port converter

A new uninterruptible power supply (UPS) topology using the high-frequency tri-port UPS technique is proposed which presents the advantages of no-break power, low cost, input unity power factor, high power density, and high power conversion efficiency. Through the proposed circuit configuration, charging concept, and control strategy, the battery management is easily obtained by controlling the output voltage of the power-factor-correction (PFC) converter, which results in no additional power device being required for charging. The implementing circuit of the charging method is submitted to perform the two-stage charging, constant current charging, and constant voltage charging. The proposed technologies can be applied to the switching power supply with built-in UPS function featuring a low-cost solution for computer equipment, Finally, an experimental AC online UPS is built to verify the proposed concept, analysis, and control strategy     

An improved charge pump power factor correction electronic ballast

An improved charge pump power factor correction (CPPFC) electronic ballast using the charge pump concept is proposed in this paper. Circuit derivation, principle of operation, and the conditions for achieving unity power factor are discussed. The proposed electronic ballast is implemented and tested with two 40 W fluorescent lamps. It is shown that 84% of overall efficiency and 1.6 of crest factor can be achieved with 200-V line input voltage. The measured line input current harmonics satisfy IEC 1000-3-2 Class C requirements. The lamp power variation range is automatically limited within ±15% for ±10% line input voltage variation without feedback control     

高增益、大功率、一体化固态T／R组件设计

本文介绍了高增益、大功率、一体化固态T／R组件的设计思想。在给定组件指标及可选功率管范围的条件下,合理的放大器级数设定及增益分配是组件实现的前提;从AC220V到组件所需的多路直流电源的转换,采用PFCSepic单相功率因数校正可以有效控制组件对系统配电的影响;BUCK型SCRC变换器开关管零电压、零电流开启、关断,以及良好的电磁兼容设计和有效的屏蔽处理是系统稳定工作的保证;合理的水道设计,解决了组件的散热问题,提高了可靠性。结构与电讯设计的融合,实现了减小组件体积、重量的目的。文中给出了组件电讯指标的实测结果,可作为其它相关工程设计参考。     

An online no-break with power factor correction and output voltage stabilization

The aim of this paper is to introduce a dc-dc converter that can be used in an online uninterruptible power supply (UPS). The proposed converter provides uninterrupted, reliable power and voltage regulation for critical loads, as well as power factor correction in supply systems. Operating principles, theoretical analysis, and control strategy are described. Digital simulation and experimental results are included, supporting the validity of the concept.     

Photovoltaic Power Conditioning System With Line Connection

A photovoltaic (PV) power conditioning system (PCS) with line connection is proposed. Using the power slope versus voltage of the PV array, the maximum power point tracking (MPPT) controller that produces a smooth transition to the maximum power point is proposed. The dc current of the PV array is estimated without using a dc current sensor. A current controller is suggested to provide power to the line with an almost-unity power factor that is derived using the feedback linearization concept. The disturbance of the line voltage is detected using a fast sensing technique. All control functions are implemented in software with a single-chip microcontroller. Experimental results obtained on a 2-kW prototype show high performance such as an almost-unity power factor, a power efficiency of 94%, and a total harmonic distortion (THD) of 3.6%.     

背腔式槽阵的谱域法

本文运用谱域法和传输线概念建立背腔式槽阵的本征方程，在窄槽情况下，与文［３］的本征方程相同。导出天线基本参数如功率传输系数，输入电压驻波比。品质因素，辐射场以及方向性系数的表达式，并以功率传输系数为例进行了数值计算。