一种输出可调智能开关稳压电源设计

设计了一种输出可调智能开关稳压电源.该系统由场效应管组成DC-DC推挽拓扑电路,采用AT89S52单片机控制DA芯片调整开关电源控制芯片SG3525输出脉宽,实现PWM控制输出电压.系统测试和运行结果表明,该稳压电源具有在一定范围内可调,结构简单,工作可靠的特点,是一种较为理想的实用化电源.     

经纬仪伺服系统功率开关电源及控制系统设计

针对经纬仪伺服系统的直流电动机的特性设计了采用脉宽调制（PWM）控制芯片和集成功率模块（IPM）的功率开关电源，主电路拓扑为全桥变换电路，功率转换器件采用集成功率模块，简化了设计，同时还有输出短路、过流、过温以及欠压保护功能，大大提高其工作可靠性，并对控制电路和保护电路进行丁设计，其输出电压连续可调。可满足不同规格的直流力矩电动机电压要求l最后通过实验验证了系统设计的有效性。     

基于DSP的开关电源的设计与实现

采用数字信号处理器设计了一种开关电源.介绍了开关电源的构成及其控制方式;描述了TMS320LF2A-07的结构特点及其在开关电源控制电路中的主要功能与实现;介绍了基于DSP的PWM型开关电源的硬件结构和软件设计流程.     

基于DSP的PWM型开关电源的设计

本文介绍了基于DSP的PWM型开关电源的原理以及设计方法,以DSP芯片TMS320F2810产生SPWM波形为例阐述了开关电源中PWM波形的实现方法。仿真结果表明,基于DSP的开关电源具有稳定快、失真小、负载对系统影响小的特点。     

TOPSwitch-FX系列单片开关电源的快速设计法

介绍TOPSwitch-FX系列单片开关电源的快速设计方法及应用实例,给出4种快速选择曲线.通过这些曲线,可快速选择TOPSwitch-FX芯片、估算电源效率和芯片功耗.文中还给出2个应用实例.对于宽范围输入情况,给出一些典型参考值.文尾提出一些设计注意事项和提高开关电源性能指标的方针.     

单端反激式开关电源中变压器的设计

变压器是开关电源中的核心元器件,它的性能好坏对整个开关电源的设计能否成功至关重要.根据设计实例,详细介绍了反激式变压器设计的一般步骤和注意事项.设计的脉冲变压器工作在CCM(连续电流模式)方式下,应用在八路输出的开关电源电路中,工作时性能稳定.     

开关电源环路控制设计

开关电源采用闭环反馈控制来达到线性负载调节和改善动态响应的目的，使输出电压稳定，因此环路控制的地位在开关电源设计中非常重要。本文的目的是为设计者提供环路反馈控制的方法，文章从环路控制的基本概念和理论开始，一步一步地详细介绍了相关的设计过程，利用Mathcad软件进行了增益和相位裕量的分析，以及它们对系统的影响。最后结合实际参数，给出了实验调试数据，验证了理论结果的正确性。     

基于UC3842的多输出开关电源设计

本文阐述了一种基于UC3842 PWM控制器的新型多路输出反激式开关电源电路的设计.该设计详细给出了变压器、漏感消除电路、启动电路以及电压电流反馈电路的设计过程.实验结果表明该电源性能优良.作为电机控制的电源模块,具有很高的应用价值.     

基于数字触发器的电源设计

介绍了一种以51系列单片机为核心,以晶闸管为开关器件,输出电压连续可调的直流电源的硬件结构和软件流程。该系统目前已应用在某高校船舶电站模拟实验室,运行效果良好。     

基于GPIB的高精度开关电源测试系统设计

针对自动化测试要求,介绍了一种高精度开关电源测试系统的设计方案,详细阐述了硬件电路的设计,采用GPIB控制技术,可以进行纹波自动测量,能实现电子负载值任意调节,从而可以非常方便地测试出不同电子负载下的电源静、动态性能.并结合硬件系统的设计,给出了系统的软件设计流程.实际运行结果表明,该系统具有扩充性强、操作方便的优点,有较高的实用价值和广阔的应用前景.     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

一个扩展的CCS

诉微分算子ＣＣＳ（Ｃａｌｃｌｕｓ ｏｆ Ｃｏｍｍｕｎｉ－ｃａｔｉｎｇ Ｓｙｓｔｅｍｓ）是由英国爱丁堡大学计算机科学系的ＲｏｂｉｎＭｉｌｎｅｒ首先提出的。ＣＣＳ是一个在数学上完整的理论算子系统,可以作为计算机通讯系统的基本理论模型。我们先简要说明一个ＣＣＳ的内容。我们所作的工作是在理论上扩充地的ＣＣＳ,使得我们的ＣＣＳ更为一般化。在我们的观战看来,ＲｏｂｉｎＭｉｂｅｒ的ＣＣＳ只不过是我们的ＣＣＳ的一     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

An Analysis of the Criteria for Evaluating Adequate Theories of Computation

This paper deals with the question: What are the criteria that an adequate theory of computation has to meet? (1) Smith’s answer: it has to meet the empirical criterion (i.e. doing justice to computational practice), the conceptual criterion (i.e. explaining all the underlying concepts) and the cognitive criterion (i.e. providing solid grounds for computationalism). (2) Piccinini’s answer: it has to meet the objectivity criterion (i.e. identifying computation as a matter of fact), the explanation criterion (i.e. explaining the computer’s behaviour), the right things compute criterion, the miscomputation criterion (i.e. accounting for malfunctions), the taxonomy criterion (i.e. distinguishing between different classes of computers) and the empirical criterion. (3) Von Neumann’s answer: it has to meet the precision and reliability of computers criterion, the single error criterion (i.e. addressing the impacts of errors) and the distinction between analogue and digital computers criterion. (4) “Everything” computes answer: it has to meet the implementation theory criterion by properly explaining the notion of implementation.     

FTDSS：高容错分布式共享存储机制

Computerized data has become critical to the survival of an enterprise. Company must have a strategy for recovering their data should data lose. RAID is a popular mechanism to offer good fault-tolerance. But RAID can notwork well when one more disks fail. In this paper, we present an efficient Network-based high High-Tolerance Dis-tributed Shared Storage mechanism called FTDSS. FTDSS makes use of disk space of node in Network to build alarge pubhc shared storage space. Users can read/write their file from/to the public storage space from node of net-work. Physically File is stored in each node in form of data fragment or XOR verify fragment. Because of redundant XOR fragments, file is available even when two more nodes fail. FTDSS realize distant redundant srorage. At last,this paper use experiment to prove that FTDSS can offer high. fault-tolerance and advanced performance.     

一种面向查询的多文档摘要方法

面向查询的多文档摘要技术有两个难点 第一,为了保证摘要与查询密切相关,容易造成摘要内容重复,不够全面;第二,原始查询难以完整描述查询意图,需进行查询扩展,而现有查询扩展方法多依赖于外部语义资源。针对以上问题,该文提出一种面向查询的多文档摘要方法,利用主题分析技术识别出当前主题下的子主题,综合考虑句子所在的子主题与查询的相关度以及子主题的重要度两方面因素来选择摘要句,并根据词语在子主题之间的共现信息,在不使用任何外部知识的情况下,进行查询扩展。在DUC2006评测语料上的实验结果表明,与Baseline系统相比,该系统取得了更高的ROUGE评价值,基于子主题的查询扩展方法则进一步提高了摘要的质量。     

Existential foundations of the composition paradigm

The theses of existonness, compoundness, and polyadness are proved. The consistency of these theses with the reversibility principle is founded. Existential foundations of the composition paradigm are constructed. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 2, pp. 3–12, March–April 2008.     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Autonomous programmable DNA nanorobotic devices using DNAzymes

A major challenge in nanoscience is the design of synthetic molecular devices that run autonomously (that is, without externally mediated changes per work-cycle) and are programmable (that is, their behavior can be modified without complete redesign of the device). DNA-based synthetic molecular devices have the advantage of being relatively simple to design and engineer, due to the predictable secondary structure of DNA nanostructures and the well-established biochemistry used to manipulate DNA nanostructures. However, ideally we would like to minimize the use of protein enzymes in the design of a DNA-based synthetic molecular device. We present the design of a class of DNA-based molecular devices using DNAzyme. These DNAzyme-based devices are autonomous, programmable, and further require no protein enzymes. The basic principle involved is inspired by a simple but ingenious molecular device due to Tian et al. [Y. Tian, Y. He, Y. Chen, P. Yin, C. Mao, A DNAzyme that walks processively and autonomously along a one-dimensional track, Angew. Chem. Intl. Ed. 44 (2005) 4355–4358] that used DNAzyme to traverse on a DNA nanostructure, but was not programmable in the sense defined above (it did not execute computations).     

A method of defuzzification based on the approach of areas' ratio

The new method of defuzzification of output parameters from the base of fuzzy rules for a Mamdani fuzzy controller is given in the paper. The peculiarity of the method is the usage of the universal equation for the area computation of the geometric shapes. During the realization of fuzzy inference linguistic terms, the structure changes from the triangular into a trapezoidal shape. That is why the universal equation is used. The method is limited and can be used only for the triangular and trapezoidal membership functions. Gaussian functions can also be used while modifying the proposed method. Traditional defuzzification models such as Middle of Maxima − MoM, First of Maxima − FoM, Last of Maxima − LoM, First of Suppport − FoS, Last of Support − LoS, Middle of Support − MoS, Center of Sums − CoS, Model of Height − MoH have a number of systematic errors: curse of dimensionality, partition of unity condition and absence of additivity. The above-mentioned methods can be seen as Center of Gravity − CoG, which has the same errors. These errors lead to the fact that accuracy of fuzzy systems decreases, because during the training root mean square error increases. One of the reasons that provokes the errors is that some of the activated fuzzy rules are excluded from the fuzzy inference. It is also possible to increase the accuracy of the fuzzy system through properties of continuity. The proposed method guarantees fulfilling of the property of continuity, as the intersection point of the adjustment linguistic terms equals 0.5 when a parametrized membership function is used. The causes of errors and a way to delete them are reviewed in the paper. The proposed method excludes errors which are inherent to the traditional and non- traditional models of defuzzification. Comparative analysis of the proposed method of defuzzification with traditional and non-traditional models shows its effectiveness.