外文资料
Summary of power flow calculation
Power system is calculated on the trend of steady-state operation of the power system as a basis, it's running under the given conditions and determine the entire system wiring in various parts of the power system running: the voltage of the bus, all components of a mid-stream power, The power loss, and so on. Power system planning in the design and operation of the existing power system in the form of research, we need to calculate the trend of using quantitative analysis of comparative power programme or operation mode is reasonable. Reliability and economy. In addition, the power flow calculation is calculated static and dynamic stability of the foundation of stability. So the trend is calculated on the power system of a very important and very basis of calculation. Power flow calculation also divided into offline and online calculation of two terms, the former mainly used for system planning and design and organization of the operation mode, while the latter is running for the system of regular monitoring and real-time control. The use of electronic digital computer to calculate the trend of the power system from the mid-1950s has already begun. Power flow problems in mathematical calculation is a group of diverse non-linear equations to solve the problem, its solution can not be separated from iteration. Therefore, the flow calculation method, it requires first and foremost a reliable convergence, and give the correct answers. As the power system structure and parameters of some of the features, and with the continuous expansion of the power system, the trend of increasing order of the equation, so the formula is not any mathematical method can guarantee is given the correct answer. This calculation of the power system to become a staff continue to seek new and more reliable way of the important factors.
Use of digital computers in the power flow problems at the beginning, the general adoption of a node admittance matrix-based successive into the law. The principle of this method is relatively simple to compare the volume of digital computer memory, to the 1950s computer manufacturing level and then the power system theoretical level. However, it is convergence of the poor, when the system large-scale change, the sharp rise in the number of iteration in the calculation of convergence are often not the case iteration. This forced the staff to the power system to calculate impedance matrix-based successive into the law. Impedance method to improve the flow of the convergence of computing, the solution of the admittance system can not solve some of the trend, in the 1960s, access to a wide range of applications, has the power system design. Operational and research has made great contribution. At present, there are still
some in the power industry units impedance method to calculate the trend. Impedance of the main shortcomings of the occupation of the computer's memory, each iteration of the large amount of calculation. When the system continue to expand, the more prominent of these shortcomings. 16 K memory of a computer in the use of impedance method can only be calculated at 100 following the system, 32 K memory of the computer can only calculate 150 nodes under the system. In this way, many of the power system in order to use impedance method shall not be first on the trend of the system is the streamlining of work. In order to overcome resistance in memory and speed of the shortcomings of the mid-1960s to the development of the impedance matrix-based Block impedance. This approach to a large-scale system divided into several small regional system, the computer only need to store various parts of the system impedance matrix contact line between them and the resistance, not only substantial savings in memory capacity, but also improve the Computing speed.
Overcome the shortcomings of the impedance of hungry is another way to use Newton - Raphson method. This is the mathematics of nonlinear equations to solve the typical method, a better convergence. In resolving the issue of power flow calculation, is admittance matrix-based, therefore, as long as we can in the iterative process as much as possible to maintain the formula coefficient matrix sparse, and can greatly improve Newton's Law trend of the efficiency of procedures . Since the mid-1960s, Newton's law in the use of the best order of elimination, the Newton in convergence. Memory requirements. Speed all over the impedance, as the late 1960s after the widespread adoption of the excellent way.
Flow calculation flexibility and convenience of the request, the application of digital computers is also a very key issue. In the past for a long time, the power flow calculation relies on the Taiwan exchange. Taiwan simulates the exchange of power systems, computing platforms in the calculation of the trend of the exchange, calculated at any time surveillance systems can run different parts of the state to meet requirements, if they run certain parts of unreasonable, you can make adjustments immediately. In this way, the equivalent of the process on the computing staff lost operating system. Adjustment process is very intuitive, physical concept is very clear. When the use of digital computers to calculate the trend when it lost this visual. To make up for this shortcoming, the trend of the establishment of procedures to the extent possible, in terms of computer calculation in the process of strengthening the process of the computer monitor and control, and to facilitate a variety of modifications and adjustments. Power flow calculation is not a simple calculation, to run it as a form of adjustment may be more precise. In order to get a reasonable run, often need to keep in accordance with the results, modify the original data. In this sense, the trend in the preparation of our program, the ease of use and flexibility must be sufficient attention. Therefore, in addition to the requirements in various ways to modify as much
as possible. Adjustment, we must pay attention to input and output of convenience and flexibility, strengthening human-computer links, so that the calculation of staff to monitor timely and appropriate calculations to control the conduct of calculation .
Power flow calculation is a power system analysis of the most basic terms, the complex power system under normal and failure conditions steady-state running the calculation. The trend is calculated to strike a target in the power system to be running the calculation. That is, voltage and power distribution node, to check whether the components of the system overload. Voltage meets all requirements of the distribution and allocation of power is reasonable and the power loss, and so on. Of the existing power system operations and expansion, the new power system planning and design of the power system for static and transient stability of the trend are calculated as the basis. If the trend of the results available on steady-state power system, or estimate the optimal security, such as the trend of the flow calculation method and the model has a direct impact. The actual power system that the main trend of technology adoption Newton - Raphson method.
In the management of the operation mode, the trend of power grid operation mode is to determine the basic starting point in planning areas, the need for trend analysis verified the reasonableness of the plan in real-time operating environment, dispatchers, provided the trend of End-expected operating conditions in the power grid To check the trend of operational reliability. In the power system dispatching a number of areas related to the trend of grid computing. Electricity network is to determine the trend of running the basic factors, the trend is steady-state power system on the basis and prerequisite .
外文文献： Knowledge of the stepper motor What is a stepper motor： Stepper motor is a kind of electrical pulses into angular displacement of the implementing agency. Popular little lesson: When the driver receives a step pulse signal, it will drive a stepper motor to set the direction of rotation at a fixed angle (and the step angle). You can control the number of pulses to control the angular displacement, so as to achieve accurate positioning purposes; the same time you can control the pulse frequency to control the motor rotation speed and acceleration, to achieve speed control purposes. What kinds of stepper motor sub-： In three stepper motors: permanent magnet (PM), reactive (VR) and hybrid (HB) permanent magnet stepper usually two-phase, torque, and smaller, step angle of 7.5 degrees or the general 15 degrees; reaction step is generally three-phase, can achieve high torque output, step angle of 1.5 degrees is generally, but the noise and vibration are large. 80 countries in Europe and America have been eliminated; hybrid stepper is a mix of permanent magnet and reactive advantages. It consists of two phases and the five-phase: two-phase step angle of 1.8 degrees while the general five-phase step angle of 0.72 degrees generally. The most widely used Stepper Motor. What is to keep the torque (HOLDING TORQUE) How much precision stepper motor? Whether the cumulative： The general accuracy of the stepper motor step angle of 3-5%, and not cumulative.
附录A Lathe fixture design and analysis Ma Feiyue (School of Mechanical Engineering, Hefei, Anhui Hefei 230022, China) Abstract: From the start the main types of lathe fixture, fixture on the flower disc and angle iron clamp lathe was introduced, and on the basis of analysis of a lathe fixture design points. Keywords: lathe fixture; design; points Lathe for machining parts on the rotating surface, such as the outer cylinder, inner cylinder and so on. Parts in the processing, the fixture can be installed in the lathe with rotary machine with main primary uranium movement. However, in order to expand the use of lathe, the work piece can also be installed in the lathe of the pallet, tool mounted on the spindle. THE MAIN TYPES OF LATHE FIXTURE Installed on the lathe spindle on the lathe fixture
at89c52单片机简介 中英文资料对照外文翻译文献综述 A T89C52 Single-chip microprocessor introduction Selection of Single-chip microprocessor 1. Development of Single-chip microprocessor The main component part of Single-chip microprocessor as a result of by such centralize to be living to obtain on the chip，In immediate future middle processor CPU。Storage RAM immediately﹑memoy read ROM﹑Interrupt system、Timer /'s counter along with I/O's rim electric circuit awaits the main microcomputer section，The lumping is living on the chip。Although the Single-chip microprocessor r is only a chip，Yet through makes up and the meritorous service be able to on sees，It had haveed the calculating machine system property，calling it for this reason act as Single-chip microprocessor r minisize calculating machine SCMS and abbreviate the Single-chip microprocessor。 1976Year the Inter corporation put out 8 MCS－48Set Single-chip microprocessor computer，After being living more than 20 years time in development that obtain continuously and wide-ranging application。1980Year that corporation put out high performance MCS －51Set Single-chip microprocessor。This type of Single-chip microprocessor meritorous service capacity、The addressing range wholly than early phase lift somewhat，Use also comparatively far more at the moment。1982Year that corporation put out the taller 16 Single-chip microprocessor MCS of performance once
如何搜索英文文献 【导读】 ①：正式发表的论文一般要进入大型的期刊论文数据库里检索； ②：搜索引擎更适合搜索普通的英文资料和论文检索入口。 一、哪里去搜索 1）图书馆 包括高校的图书馆、科研单位的图书馆、地方图书馆（如：国家图书馆、上海图书馆） 图书馆一般购买了大量的期刊论文数据库，供内部人员免费使用。 有中文为主的万方、维普，有外文的ProQuest、Springer 等。 注1：图书馆一般都提供文献代检服务，不过可能要收取一定费用。 注2：通过IP 代理的方式可以访问图书馆的这些数据库，不过是非法的。 2）利用在线期刊、论文数据库 国内的有： 中国知网：国家科技图书文献中心：万方
数据：或…… 国外的有：ScienceDirect：：：…… 注：当然，除了国外的部分数据库有少量文献可以免费查看全文之外，都是要付费的。 这就需要登录这些数据库的帐号和密码，或者是代理IP。 3）利用搜索引擎 一般来说，英文的用Google 来搜索要好一点，因为它收录了大量国外的网站。 而百度主要针对国内的，如果你的话题是特别中国化的，那么百度也是不错的选择。 由于正式文档一般都采用pdf，要搜索pdf 文档，只需在关键词后，加个filetype:pdf 即可 除了以网页模式之外，还可以在Google 学术里或是百度文档里搜索，二者互为补充。 注：具体参见《搜索引擎常用技巧——英文资料篇》
4）利用免费文献网站 免费和收费是相对的，有些网站是全面免费，有些是部分免费， 而有些是等论文发表过了一定期限后才免费。 HighWire Press：：：更多网站>> 5）向论文作者或网友求助 直接给论文作者发电子邮件，还是有一定机会得到回复的。 另外，有些作者会把自己的论文放在个人网站上。 至于网络求助，可以进入高校的论坛或者一些学术网站。 二、如何确定英文关键词 搜索英文资料的关键，还是要找到准确描述搜索内容的“英文关键词” 大家可以去这儿查： 1）知网翻译助手：（因为是根据论文内容来确定的，词汇或表达都比较准确）2）爱词霸：（金山词霸里有不少专业词典，网上的“百科词典”里的词条也有参考价值）
1. Introduction America is one of the countries that speak English. Because of the special North American culture, developing history and the social environment, American English has formed its certain unique forms and the meaning. Then it turned into American English that has the special features of the United States. American English which sometimes also called United English or U.S English is the form of the English language that used widely in the United States .As the rapid development of American economy, and its steady position and strong power in the world, American English has become more and more widely used. As in 2005, more than two-thirds of English native speakers use various forms of American English. The philologists of the United States had divided the English of the United States into four major types: “America n creating”; “Old words given the new meaning”; “Words that eliminated by English”;“The phonetic foreign phrases and the languages that are not from the English immigrates”[1]. Compared to the other languages, American English is much simple on word spelling, usage and grammar, and it is one of the reasons that American English is so popular in the world. The thesis analyzes the differences between American English and British English. With the main part, it deals with the development of American English, its peculiarities compared to that of British English, its causes and tendency. 2. Analyses the Differences As we English learners, when we learning English in our junior or senior school, we already came across some words that have different spellings, different pronunciations or different expressions, which can be represented by following contrasted words: spellings in "color" vs. "colour"; pronunciations in "sec-re-ta-ry" vs. "sec-re-try";
MCS-51系列单片机 中英文资料对照外文翻译文献综述 Structure and function of the MCS-51 series Structure and function of the MCS-51 series one-chip computer MCS-51 is a name of a piece of one-chip computer series which Intel Company produces. This company introduced 8 top-grade one-chip computers of MCS-51 series in 1980 after introducing 8 one-chip computers of MCS-48 series in 1976. It belong to a lot of kinds this line of one-chip computer the chips have, such as 8051, 8031, 8751, 80C51BH, 80C31BH,etc., their basic composition, basic performance and instruction system are all the same.8051 daily representatives-51 serial one-chip computers. A one-chip computer system is made up of several following parts: (1) One microprocessor of 8 (CPU). ( 2) At slice data memory RAM (128B/256B),it use not depositing not can reading /data that write, such as result not middle of operation, final result and data wanted to show, etc. (3) Procedure memory ROM/EPROM (4KB/8K B ), is used to preserve the
2604130359 CNC Cutting Technology Review Numerical control high speed cutting technology (High Speed Machining, HSM, or High Speed Cutting, HSC), is one of the advanced manufacturing technology to improve the machining efficiency and quality, the study of related technology has become an important research direction of advanced manufacturing technology at home and abroad. China is a big manufacturing country, in the world of industry transfer to accept the front instead of back-end of the transfer, to master the core technology of advanced manufacturing, or in a new round of international industrial structure adjustment, our country manufacturing industry will further behind. Imminent research on the theory and application of advanced technology. 1, high-speed CNC machining meaning High speed cutting theory put forward by the German physicist Carl.J.Salomon in the last century and early thirty's. He concluded by a lot of experiments: in the normal range of cutting speed, cutting speed if the increase, will cause the cutting temperature rise, exacerbating the wear of cutting tool; however, when the cutting speed is increased to a certain value, as long as more than the inflection point, with the increase of the cutting speed, cutting temperature can not rise, but will decline, so as long as the cutting speed is high enough, it can be solved very well in high cutting temperature caused by tool wear is not conducive to the cutting problem, obtained good processing efficiency. With the development of manufacturing industry, this theory is gradually paid more attention to, and attracted a lot of attention, on the basis of this theory has gradually formed the field of high-speed cutting technology of NC, relatively early research on NC High-speed Machining Technology in developed countries, through the theoretical basis of the research, basic research and applied research and development application, at present applications have entered the substantive stage in some areas. The high-speed cutting processing category, generally have the following several kinds of classification methods, one is to see that cutting speed, cutting speed over conventional cutting speed is 5-10 times of high speed cutting. Also has the scholar to spindle speed as the definition of high-speed processing standards, that the spindle speed is higher than that of 8000r\/min for high speed machining. And from the machine tool spindle design point of view, with the product of DN diameter of spindle and spindle speed, if the value of DN to (5~2000) * 105mm.r\/min, is considered to be of high speed machining. In practice, different processing methods, different materials, high speed cutting speed corresponding to different. Is generally believed that the turning speed of (700~7000) m\/min, milling speed reaches m\/min (300~6000), that is in the high-speed cutting. In addition, from the practical considerations, high-speed machining concept not only contains the high speed cutting process, integration and optimization also contains the process of cutting, is a
Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.
中文资料原文 单片机 单片机也被称为微控制器（Microcontroller Unit），常用英文字母的缩写MCU表示单片机，它最早是被用在工业控制领域。单片机由芯片内仅有CPU的专用处理器发展而来。最早的设计理念是通过将大量外围设备和CPU集成在一个芯片中，使计算机系统更小，更容易集成进复杂的而对体积要求严格的控制设备当中。INTEL的Z80是最早按照这种思想设计出的处理器，从此以后，单片机和专用处理器的发展便分道扬镳。 早期的单片机都是8位或4位的。其中最成功的是INTEL的8031，因为简单可靠而性能不错获得了很大的好评。此后在8031上发展出了MCS51系列单片机系统。基于这一系统的单片机系统直到现在还在广泛使用。随着工业控制领域要求的提高，开始出现了16位单片机，但因为性价比不理想并未得到很广泛的应用。90年代后随着消费电子产品大发展，单片机技术得到了巨大提高。随着INTEL i960系列特别是后来的ARM系列的广泛应用，32位单片机迅速取代16位单片机的高端地位，并且进入主流市场。而传统的8位单片机的性能也得到了飞速提高，处理能力比起80年代提高了数百倍。目前，高端的32位单片机主频已经超过300MHz，性能直追90年代中期的专用处理器，而普通的型号出厂价格跌落至1美元，最高端[1]的型号也只有10美元。当代单片机系统已经不再只在裸机环境下开发和使用，大量专用的嵌入式操作系统被广泛应用在全系列的单片机上。而在作为掌上电脑和手机核心处理的高端单片机甚至可以直接使用专用的Windows和Linux操作系统。 单片机比专用处理器更适合应用于嵌入式系统，因此它得到了最多的应用。事实上单片机是世界上数量最多的计算机。现代人类生活中所用的几乎每件电子和机械产品中都会集成有单片机。手机、电话、计算器、家用电器、电子玩具、掌上电脑以及鼠标等电脑配件中都配有1-2部单片机。而个人电脑中也会有为数不少的单片机在工作。汽车上一般配备40多部单片机，复杂的工业控制系统上甚至可能有数百台单片机在同时工作！单片机的数量不仅远超过PC机和其他计算的总和，甚至比人类的数量还要多。 单片机又称单片微控制器,它不是完成某一个逻辑功能的芯片,而是把一个计算机系统集成到一个芯片上。相当于一个微型的计算机，和计算机相比，单片机只缺少了I/O设备。概括的讲：一块芯片就成了一台计算机。它的体积小、质量轻、价格便宜、为学习、应用和开发提供了便利条件。同时，学习使用单片机是了解计算机原理与结构的最佳选择。
A review and analysis of current computer-aided fixture design approaches Iain Boyle, Yiming Rong, David C. Brown Keywords: Computer-aided fixture design Fixture design Fixture planning Fixture verification Setup planning Unit design ABSTRACT A key characteristic of the modern market place is the consumer demand for variety. To respond effectively to this demand, manufacturers need to ensure that their manufacturing practices are sufficiently flexible to allow them to achieve rapid product development. Fixturing, which involves using fixtures to secure work pieces during machining so that they can be transformed into parts that meet required design specifications, is a significant contributing factor towards achieving manufacturing flexibility. To enable flexible fixturing, considerable levels of research effort have been devoted to supporting the process of fixture design through the development of computer-aided fixture design (CAFD) tools and approaches. This paper contains a review of these research efforts. Over seventy-five CAFD tools and approaches are reviewed in terms of the fixture design phases they support and the underlying technology upon which they are based. The primary conclusion of the review is that while significant advances have been made in supporting fixture design, there are primarily two research issues that require further effort. The first of these is that current CAFD research is segmented in nature and there remains a need to provide more cohesive fixture design support. Secondly, a greater focus is required on supporting the detailed design of a fixture’s physical structure. 2010 Elsevier Ltd. All rights reserved. Contents 1. Introduction (2) 2. Fixture design (2) 3. Current CAFD approaches (4) 3.1 Setup planning (4) 3.1.1 Approaches to setup planning (4) 3.2 Fixture planning (4) 3.2.1 Approaches to defining the fixturing requirement (6) 3.2.2 Approaches to non-optimized layout planning (6) 3.2.3 Approaches to layout planning optimization (6) 3.3 Unit design (7) 3.3.1 Approaches to conceptual unit design (7)
文献检索是非常麻烦的事情，一般都是通过各种数据库进行检索，但由于购买的电子数据库基本都只有1997年以后的文献，文献量比较少，而且很多领域属于落后于国外20-30年的研究，一般很难查到，即使能查到出处，但无原文。文献查找是个费时费力的事情，需要细心和耐心，反复查找，以下谈谈个人关于如何利用网络进行文献查找的一些经验。 ①搜索引擎的高级功能 搜索引擎主要https://www.doczj.com/doc/a017727973.html,和https://www.doczj.com/doc/a017727973.html,，https://www.doczj.com/doc/a017727973.html,则仅在检索中文时稍好点，英文很差，用处不大。我们常用的google侧重于网页的检索，Scholar则主要针对学术类文献进行检索，格式主要是pdf，对于论文的引用也会显示，对于知道文献名和作者的情况比较容易直接找到pdf文档，一般这两个搜索引擎要联合使用。 Google的高级检索功能中有几个常用的功能： （1）锁定关键词检索：使用双引号如”停车”，则所有检索结果均包含双引号中的内容，以减少检索结果量； （2）文件类型检索：文件类型主要是.pdf和.doc文档，国外文献大部分以pdf格式发布，使用格式限制可以排除很多不必要的检索结果，如输入：停车filetype:pdf，当然其它google 识别的格式都可使用； （3）指定网址检索：如果发现某个网站有需要的文献，则可以直接指定到该网站检索，以获得需要的资料，如输入：停车site:https://www.doczj.com/doc/a017727973.html,。 Google的详细功能请参照google的高级检索，百度在使用上相同。 ②关键词的使用 检索结果如何，和关键词的使用直接相关，所以，首先要弄清楚在英文中关键词有哪几种表达方式，分别进行检索，而对于文献综述类，可以使用：review、overview、literature review、history、development、trend等和关键词一起检索。 关键词的检索并不是一次就能确定下来的，刚开始选用几个看能否找到，如果找到一些，先初步看看那些文献，对内容有了更深一些的认识后同时也对检索关键词增加了了解，实际上是不断调整检索关键词的过程 ③参考文献的使用 检索到一些文章后，先要看看文献后的参考文献，国外文献一般都会很详细的列出，可根据参考文献相应的进行有目的的检索，如找到指定数据库的期刊，或者检索作者，作者的个人主页一般提供作者本人发表文献的下载（最好的资源），有些还提供作者的E-mal，可直接写信给作者，一般对方都会提供。 另外，利用google的强大功能，对论文题名、期刊和作者进行检索，期刊的检索经常能发现该期刊被那个数据库收录，则可直接到相应的数据库找到，检索作者则最好加关键词、年等信息以缩小检索范围，而且不要用缩写，会忽略很多信息。 如果找到某个期刊历年的电子数据库，虽然网站有自己的检索功能，但最好不要检索之后其它就放弃了，实际上很多文献不一定检索得到，需要有耐心的一期一期的去看（当然实际上这个工作量并不大，国外的期刊一般每期也就10篇左右），但如果错过了需要的文献则损失
（ 本科毕业设计外文文献翻译 学校代码： 10128 学 号： 题 目：Shear wall structural design of high-level framework 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程专业（建筑工程方向） 班 级：土木08-（5）班 指导教师： (副教授)
Shear wall structural design of high-level framework Wu Jicheng Abstract: In this paper the basic concepts of manpower from the frame shear wall structure, analysis of the structural design of the content of the frame shear wall, including the seismic wall shear span ratio design, and a concrete structure in the most commonly used frame shear wall structure the design of points to note. Keywords: concrete; frame shear wall structure; high-rise buildings The wall is a modern high-rise buildings is an important building content, the size of the frame shear wall must comply with building regulations. The principle is that the larger size but the thickness must be smaller geometric features should be presented to the plate, the force is close to cylindrical. The wall shear wall structure is a flat component. Its exposure to the force along the plane level of the role of shear and moment, must also take into account the vertical pressure. Operate under the combined action of bending moments and axial force and shear force by the cantilever deep beam under the action of the force level to look into the bottom mounted on the basis of. Shear wall is divided into a whole wall and the associated shear wall in the actual project, a whole wall for example, such as general housing construction in the gable or fish bone structure film walls and small openings wall. Coupled Shear walls are connected by the coupling beam shear wall. But because the