基于PIC16C72单片机的线性V／F转换器设计

电压到频率的变化是过程控制、智能仪表和通信中的常用技术。电压／频率转换电路(简称V／F可用作精密电压／频率转换器、数／模转换器．模／数转换器、长时间积分器、线性频率调制或解调以及其他功能电路；具有良好的精度、线性度、积分输入特性与抗干扰性能，易于远距离传送，能提供其他类型转换器无法达到的性能。利用PIC16C72单片机既可以测量电压又可以输出频率，所以无须外部附加复杂的硬件电路就可以方便地实现电压到频率的变换。     

基于集成化设计的高性能双级型功率因数校正AC／DC变流器——分析、设计及电路实验

目前，具有功率因数校正的AC／DC变流器可以分为两大类：一类是单级变流器，变流器中AC／DC及DC／DC变换共用一个功率开关，因此，只需要一个控制回路。此类变流器通常工作在电流不连续模式下，其优点是电路结构简单、成本低、可靠性高。另一类则是级联结构的双级型变流器，它由前端AC／DC变换器（包括PFC电路）和后端DC／DC变换器级联而成，它适合于大功率负载的使用。此类变流器的一个突出的优点体现在前端和后端变换器可以独立地进行优化设计以取得各自优良的工作特性。本论文系统及深入地分析了单级型与双级型功率因数校正AC／DC变流器的’性能特征，并指出各自存在的优点及不足之处；在此基础上，结合软开关技术的特点，提出了一种基于集成化设计的双级型功率因数校正AC／DC开关变流器电路，它通过使变流器中被两次处理的功率比例最小化，以及通过重新构建现有单／双级电路拓扑与优化利用单／双级型电路两者之间固有关系等措施，来获得变流器的高功率因数及高工作效率；研究内容包括：优化的功率系统结构，功率主电路拓扑，控制技术等，文中最后给出了电路的实验参数及关键工作波形。     

基本DC／DC变换器拓扑及其变换

本文简要地介绍了基本DC／DC变换器的基本结构及基本原理，并以buck电路为基础，变换组合出各种变换器电路。     

一种改善MC68HC908GP32单片机A/D转换性能的方法

以改善MC68HC908GP32的A／D转换性能为目的，给出了一个主要由MC68HC908GP52和ADS7815构造的电路，描述了电路的结构、工作原理，说明了A／D转换性能改善的结果。     

铂电阻多点测温控温设计

在生物芯片反应仪中采用铂电阻测温时．设计了精密低温度漂移电流源来转换电阻信号为电压信号。信号调理电路采用减法电路，串行A／DTLC1543对三路信号采集．电路简洁，准确度高．控制可靠。     

基于PDIUSBD12的USB格式通信

USB(Universal Serial Bus)，通用串行总线，是COMPAQ，INTEL，MICROSOFT，NEC等几家公司联合推出的一种快速双向、并可以进行热插拔的接口。基于USB1．1规范，接口最高传输速度可迭12Mb／s，是数据、语音静态图像传输的理想选择，在USB1．1基础上，可方便的加入硬件电路，使数码照相机、手机、PDA的以USB格式与电脑通信，下载或保存重要的数据实现信息最优化。     

AT89C2051单片机与8155的接口设计

本文介绍了AT89C2051单片机与可编程I／O接口芯片8155的接口设计，给出了接口电路和程序清单。     

C波段大功率T／R组件设计

本文介绍了一种相控阵用c波段大功率T／R组件的设计实现方法。通过分析整机技术要求,借助微波CAD辅助设计软件,采用固态功率放大器,并针对各功能部件选取合适的电路形式,设计并制作完成C波段大功率T／R组件样品,并给出了测试结果。     

织物漂白和消毒用复配物

长期以来，人们一直用各种化合物水溶液对织物进行漂白和／或消毒。这些化合物通常以次氯酸或次氯酸根离子的形式存在于水溶液中，具体情况视水溶液pH值的大小而定。     

更柔软、更接近、更快速

有弹性的电路板今天的电路通常都制作在易碎的半导体或玻璃上,但是下一代电路也许将像橡胶那样富有弹性。美国伊利诺伊大学的科学家将只有人类头发直径1／500的硅电路印刷在了有弹性的塑料上,能像手风琴一样任意拉伸或者压缩。预计在5年内,这种弹性电路板将被用于制造电极,这种电极能直接安放在人类大脑内,对癫痫患者的大脑活动进行研究。     

集成电路知识产权相关问题的探讨

文章主要分析了集成电路产业知识产权的现状以及集成电路知识产权的保护形式、类型和特点;探讨了获得集成电路布图设计专有权的条件、具体权利、权利限制以及侵权的问题,提出集成电路行业加强知识产权保护的几项具体建议。     

变压器出口短路后电气试验的探讨

在大短路电流作用下,机械损伤的基本形式是变压器绕组变形,它们发展的典型方式是变形引起局部放电,匝、层间短路,整段主绝缘放电或完全击穿导致主绝缘破坏。因此,变压器出口短路后的检测试验一项必要的关系到运行安全的重要工作。     

模糊Petri网在电子商务领域应用研究

在模糊Petri网的与规则和或规则基础之上,对模糊Petri网的产生式规则进行了细分,得出4种不同类型的规则。针对电子商务中电子支付安全问题,建立模糊Petri网模型,并结合实例对模型进行实验验证,为研究电子商务安全问题提供了一种新的思路和方法。     

A matrix generalization of heaviside's expansion theorem

Starting with the energy and dissipation functions of the general n mesh linear bilateral network and using the operational methods of the Laplacian transformation, a solution is obtained for the Lagrangian equations of the system subject to initial boundary conditions. The equations take a particularly simple and general form if matrix notation is used.It is noted that the general case bears a close resemblance to the simple, one mesh, series circuit when the scalar factors which appear in this circuit are generalized to matrix form.     

Aspects and the overlap function

It is intuitively clear that putting the cart before the horse is not the same as putting the horse before the cart. It is equally clear that a history of philosophy is different from a philosophy of history. Yet there is no logical relationship, like the AND/OR/NOT functions, which would enable manipulation of these permuted, non-commutative, relationships. In this paper we present a system for automatic handling of ordered sets, states based on these sets, and of differing points of view regarding a Universe of Discourse. We call what we are dealing with aspects and we represent them by means of a new logical function called the Overlap function.     

基于TPS雷达电路板测试软件系统架构与实现

雷达含有多块不同种类的电路板,包括电源、发射、接收、信号、终端、监控等。由于雷达任务的紧迫性,这些电路板在发生故障时,对雷达系统影响非常大。随着电子设备的日益复杂化,越来越需要形成一个自动的对雷达电路板进行测试的系统,即自动测试系统(Automatic Test System)。本文分析了雷达板级测试软件的功能要求,提出了基于测试程序集(TPS)的自动测试系统软件架构及实现方法。该软件已成功应用于多个雷达板级自动测试台。     

Automatic construction of information queries

The methods of information queries building in the SDI systems on the basis of the user's publications are presented in this paper. In most cases the users of the SDI system are scientists whose work is marked by publications resulting from the research they do. It was found that the users' publications may constitute input data for information queries building.The examination of the possible compatibility between the user's information queries and his publications consisted of determining the similarity between of a set of keywords indexed from the information query and a set of keywords indexed from the user's publications.Two methods of information query constructions determined by logical operators AND, OR, NOT and a set of weighted keywords are described.     

Data dropout compensation for networked control systems under a new parallel-triggering approach

The logical AND/OR combination of two trigger conditions leads to a class of event triggering approach called parallel-triggering that is not sufficiently considered in conception and application. This paper first proposes the relative-absolute parallel-triggering for both the continuous-time and the discrete-time paradigms. In the continuous-time paradigm, a weighted switching parallel-triggering (SPT) is studied that outperforms the existing discrete-time periodic parallel-triggering (PPT) approach. The next point of this paper is the issue of considering the data dropout effect. In this regard, the maximum number of sequential data dropouts is estimated for both parallel-triggering paradigms. The weighted matrix of the trigger condition, as a degree of freedom, can be beneficial for the feasibility of linear matrix inequality (LMI) in the stability analysis. A square root transformation is applied to change the coordinate and analyze the weighted trigger condition. Finally, by using some numerical simulation, our results are evaluated.     

Design of CMOS Mixer with Complementary Transconductance

<正>A current bleeding CMOS mixer with complementary transconductance stage is presented in this paper.The conversion gain of the mixer is increased and the flick noise of the mixer is reduced by inserting the PMOS to form current bleeding circuit in Gilbert mixer.The circuit is designed through SMIC 0.18um CMOS process,the LO frequency is 1.571GHz,RF frequency is 1.575GHz,simulation results show the conversion gain of the mixer is 18.5 dB,SSB NF is about 9.59dB,and third-order input intercept point(IIP3) is-4.6dBm.The mixer consumes 7.8 mA at 1.8 V power supply and the size of the whole layout is 0.73mm×0.68 mm.     

Covariant formulation of Faraday's law

A manifestly Lorentz covariant form of Faraday's law is presented. This leads to a general expression of the electromotive force induced in a circuit moving in an arbitrary manner, including deformations, as determined by an observer in uniform motion in the given reference frame. This quantity is a Lorentz scalar, but it depends on the state of motion of the observer. It is also shown that only changes in the geometrical curve matter for the determination of the electromotive force, and not the actual motion of the circuit along the curve.