计算机系外文翻译---历史的计算

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外文翻译--计算机

外文翻译--计算机

外文原文computerThe modern world of high technology could not have come about except for the development of the computer. Different types and sizes of computers find uses throughout society in the storage and handling of data, from secret governmental files to banking transactions to private household accounts. Computers have opened up a new era in manufacturing through the techniques of automation, and they have enhanced modern communication systems. They are essential tools in almost every field of research and applied technology, from constructing models of the universe to producing tomorrow’s weather reports, and technique use has in itself opened up new areas of conjecture. Database services and computer networks make available a great variety of information sources. The same advanced techniques also make the invasions of privacy and restricted information sources possible, and computer crime has become one of the many risks that society must face if it is to enjoy the benefits of modern technology.A computer is an electronic device that can receive a set of instructions, or program, and then carry out this program by performing calculations on numerical data or by compiling and correlating other forms of information. The type of computers are mainly inclusive of Microcomputer, Minicomputer, Mainframe Computer and Supercomputer, etc. Microminiaturization , the effort to compress more circuit elements into smaller and smaller chip space is becoming the major trend in computer development. Besides, researchers are trying to develop more powerful and more advanced computers.Any customers all pass the operate system to use the calculator, not direct carry on the operation to the hardware of the calculators. The operate system is a bridge that communicates the customer and calculator. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks and provide a software platform. The choice of operating systems determines to a great extent of the applications. Therefore OS is very important.The operate system is in the charge of Computer resource control program to execute system software. Say in a specific way,the OS is the most basic in the calculator software system, also constituting the part most importantly, it is responsible for the management and controls the calculator system in all hardware resources and the software resources, can make of various resources matched with mutually, moderating to work with one accord, full develop its function, exaltation the efficiency of the system, still take the interface function of the customer and the calculator system at the same time, use the calculator to provide the convenience for the customer. The operate system is a huge management control procedure, including 5 management functions mostly: Progress and processing the machine manage, the homework manage, saving management, equipments management, document management. Divide the line from the function, the tiny machine operate system can is divided into the single mission operate system, single many mission operate systems of customer and many mission operate systems of multi-user of single customer. At present there are several kinds of OS on the computer which are DOS, OS/2, UNIX, XENIX, LINUX, Window2000, Netware etc.In order for a computer to perform the required task, it must be given instructions in a language that it understands. However, the computer’s own binary based language, or machine language, is difficult for humans to use. Therefore, people devised an assembly language to shorten and simplify the process. In order to make a computer more friendly to use, programmers invented high level languages, such as COBOL, FORTRAN, ASSEMBLER, PASCAL, C++, etc, which made the computers easier to use. For the time being, HTML and XML are very useful languages as well.The database is often used to describe a collection of related data that is organized into an integrated, sophisticated structure that provides different people with varied access to the same data. A database management system is an extremely complex set of software programs that controls the organization, storage and retrieval of data in a database. A successful DBMS is often characterized with the four principal features: (1)Data Security and Integrity; (2)Interactive query; (3)Interactive data Entry and Updating; (4)Data Independence. The intelligent databases are becoming more popular in that they canprovide more validation. The researches on new types of database systems are underway.计算机倘若不是伴随着计算机的发展,现代世界的高端技术不可能出现。

计算机专业外文文献及翻译

计算机专业外文文献及翻译

微软Visual Studio1微软Visual StudioVisual Studio 是微软公司推出的开发环境,Visual Studio可以用来创建Windows平台下的Windows应用程序和网络应用程序,也可以用来创建网络服务、智能设备应用程序和Office 插件。

Visual Studio是一个来自微软的集成开发环境IDE,它可以用来开发由微软视窗,视窗手机,Windows CE、.NET框架、.NET精简框架和微软的Silverlight支持的控制台和图形用户界面的应用程序以及Windows窗体应用程序,网站,Web应用程序和网络服务中的本地代码连同托管代码。

Visual Studio包含一个由智能感知和代码重构支持的代码编辑器。

集成的调试工作既作为一个源代码级调试器又可以作为一台机器级调试器。

其他内置工具包括一个窗体设计的GUI应用程序,网页设计师,类设计师,数据库架构设计师。

它有几乎各个层面的插件增强功能,包括增加对支持源代码控制系统(如Subversion和Visual SourceSafe)并添加新的工具集设计和可视化编辑器,如特定于域的语言或用于其他方面的软件开发生命周期的工具(例如Team Foundation Server的客户端:团队资源管理器)。

Visual Studio支持不同的编程语言的服务方式的语言,它允许代码编辑器和调试器(在不同程度上)支持几乎所有的编程语言,提供了一个语言特定服务的存在。

内置的语言中包括C/C + +中(通过Visual C++),(通过Visual ),C#中(通过Visual C#)和F#(作为Visual Studio 2010),为支持其他语言,如M,Python,和Ruby等,可通过安装单独的语言服务。

它也支持的XML/XSLT,HTML/XHTML,JavaScript和CSS.为特定用户提供服务的Visual Studio也是存在的:微软Visual Basic,Visual J#、Visual C#和Visual C++。

计算机专业外文翻译--c 的起源一个小的历史

计算机专业外文翻译--c  的起源一个小的历史

外文原文The Origins of C++: A Little HistoryComputer technology has evolved at an amazing rate over the past few decades. Today a notebook computer can compute faster and store more information than the mainframe computers of the 1960s. Computer languages have evolved, too. The changes may not be as dramatic, but they are important. Bigger, more powerful computers spawn bigger, more complex programs, which, in turn, raise new problems in program management and maintenance.In the 1970s, languages such as C and Pascal helped usher in an era of structured programming,a philosophy that brought some order and discipline to a field badly in need of these qualities. Besides providing the tools for structured programming, C also produced compact,fast-running programs, along with the ability to address hardware matters, such as managing communication ports and disk drives. These gifts helped make C the dominant programming language in the 1980s. Meanwhile, the 1980s witnessed the growth of a new programming paradigm: object-oriented programming, or OOP, as embodied in languages such as SmallTalk and C++. Let’s examine these C and OOP a bit more closely.The Mechanics of Creating a ProgramSuppose you’ve written a C++ program. How do you get it running? The exact steps depend on your computer environment and the particular C++ compiler you use, but they should resemble the following steps:1. Use a text editor of some sort to write the program and save it in a file. This file constitutes the source code for your program.2. Compile the source code. This means running a program that translates the source code to the internal language, called machine language, used by the host computer. The file containing the translated program is the object code for your program.3. Link the object code with additional code. For example, C++ programs normally use libraries. A C++ library contains object code for a collection of computer routines, called functions, to perform tasks such as displaying information onscreen or calculating the square root of a number. Linking combines your object code with object code for the functions you use and with some standard startup code to produce a runtime version of your program. The file containing this final product is called the executable code.CAsyncSocketA CAsyncSocket object represents a Windows Socket — an endpoint of network communication. Class CAsyncSocket encapsulates the Windows Sockets API, providing an object-oriented abstraction for programmers who want to use Windows Sockets in conjunction with MFC.This class is based on the assumption that you understand network communications. You are responsible for handling blocking, byte-order differences, and conversions between Unicode and multibyte character set (MBCS) strings. If you want a more convenient interface that manages these issues for you, see class CSocket.To use a CAsyncSocket object, call its constructor, then call the Create function to create the underlying socket handle (type SOCKET), except on accepted sockets. For a server socket call the Listen member function, and for a client socket call the Connect member function. The server socket should call the Accept function upon receiving a connection request. Use the remaining CAsyncSocket functions to carry out communications between sockets. Upon completion, destroy the CAsyncSocket object if it was created on the heap; the destructor automatically calls the Close function.CsocketClass CSocket derives from CAsyncSocket and inherits its encapsulation of the Windows Sockets API. A CSocket object represents a higher level of abstraction of the Windows Sockets API than that of a CAsyncSocket object. CSocket works with classes CSocketFile and CArchive to manage the sending and receiving of data.A CSocket object also provides blocking, which is essential to the synchronous operation of CArchive. Blocking functions, such as Receive, Send, ReceiveFrom, SendTo, and Accept (all inherited from CAsyncSocket), do not return a WSAEWOULDBLOCK error in CSocket. Instead, these functions wait until the operation completes. Additionally, the original call will terminate with the error WSAEINTR if CancelBlockingCall is called while one of these functions is blocking.To use a CSocket object, call the constructor, then call Create to create the underlying SOCKET handle (type SOCKET). The default parameters of Create create a stream socket, but if you are not using the socket with a CArchive object, you can specify a parameter to create a datagram socket instead, or bind to a specific port to create a server socket. Connect to a client socket using Connect on the client side and Accept on the server side. Then create a CSocketFile object and associate it to the CSocket object in the CSocketFile constructor. Next, create a CArchive object for sending and one for receiving data (as needed), then associate them with the CSocketFile object in the CArchive constructor. When communications are complete, destroy the CArchive, CSocketFile, and CSocket objects.CSocketFileA CSocketFile object is a CFile object used for sending and receiving data across a network via Windows Sockets. You can attach the CSocketFile object to a CSocket object for this purpose. You also can — and usually do — attach the CSocketFile object to a CArchive object to simplify sending and receiving data using MFC serialization.To serialize (send) data, you insert it into the archive, which calls CSocketFile member functions to write data to the CSocket object. To deserialize (receive) data, you extract from the archive. This causes the archive to call CSocketFile member functions to read data from the CSocket object.Tip Besides using CSocketFile as described here, you can use it as a stand-alone file object, just as you can with CFile, its base class. You can also use CSocketFile with any archive-based MFC serialization functions. Because CSocketFile does not support all of CFile’s functionality, some default MFC serialize functions are not compatible with CSocketFile. This is particularly true of the CEditView class. You should not try to serialize CEditView data through a CArchive object attached to a CSocketFile object using CEditView::SerializeRaw; use CEditView::Serialize instead. The SerializeRaw function expects the file object to have functions, such as Seek, that CSocketFile does not have.Using the MFC Source FilesThe Microsoft Foundation Class Library (MFC) supplies full source code. Header files (.H) are in the MFC\Include directory; implementation files (.Cpp) are in the MFC\Src directory.Note The MFC\Src directory contains a makefile you can use with NMake to build MFC library versions, including a browse version. A browse version of MFC is useful for tracing through the calling structure of MFC itself. The file Readme.Txt in that directory explains how to use this makefile.This family of articles explains the conventions that MFC uses to comment the various parts of each class, what these comments mean, and what you should expect to find in each section. ClassWizard and AppWizard use similar conventions for the classes they create for you, and you will probably find these conventions useful for your own code.You might be familiar with the public, protected, and private C++ keywords. When looking at the MFC header files, you'll find that each class may have several of each of these. For example, public member variables and functions might be under more than one public keyword. This is because MFC separates member variables and functions based on their use, not by the type of access allowed. MFC uses private sparingly — even items considered implementation details are generally protected and many times are public. Although access to the implementation details is discouraged, MFC leaves the decision to you.中文译文c++的起源:一个小的历史过去的几十年计算机技术以惊人的速度得到发展。

计算机科学与技术专业外文翻译--数据库

计算机科学与技术专业外文翻译--数据库

外文原文:Database1.1Database conceptThe database concept has evolved since the 1960s to ease increasing difficulties in designing, building, and maintaining complex information systems (typically with many concurrent end-users, and with a large amount of diverse data). It has evolved together with database management systems which enable the effective handling of databases. Though the terms database and DBMS define different entities, they are inseparable: a database's properties are determined by its supporting DBMS and vice-versa. The Oxford English dictionary cites[citation needed] a 1962 technical report as the first to use the term "data-base." With the progress in technology in the areas of processors, computer memory, computer storage and computer networks, the sizes, capabilities, and performance of databases and their respective DBMSs have grown in orders of magnitudes. For decades it has been unlikely that a complex information system can be built effectively without a proper database supported by a DBMS. The utilization of databases is now spread to such a wide degree that virtually every technology and product relies on databases and DBMSs for its development and commercialization, or even may have such embedded in it. Also, organizations and companies, from small to large, heavily depend on databases for their operations.No widely accepted exact definition exists for DBMS. However, a system needs to provide considerable functionality to qualify as a DBMS. Accordingly its supported data collection needs to meet respective usability requirements (broadly defined by the requirements below) to qualify as a database. Thus, a database and its supporting DBMS are defined here by a set of general requirements listed below. Virtually all existing mature DBMS products meet these requirements to a great extent, while less mature either meet them or converge to meet them.1.2Evolution of database and DBMS technologyThe introduction of the term database coincided with the availability of direct-access storage (disks and drums) from the mid-1960s onwards. The term represented a contrast with the tape-based systems of the past, allowing shared interactive use rather than daily batch processing.In the earliest database systems, efficiency was perhaps the primary concern, but it was already recognized that there were other important objectives. One of the key aims was to make the data independent of the logic of application programs, so that the same data could be made available to different applications.The first generation of database systems were navigational,[2] applications typically accessed data by following pointers from one record to another. The two main data models at this time were the hierarchical model, epitomized by IBM's IMS system, and the Codasyl model (Network model), implemented in a number ofproducts such as IDMS.The Relational model, first proposed in 1970 by Edgar F. Codd, departed from this tradition by insisting that applications should search for data by content, rather than by following links. This was considered necessary to allow the content of the database to evolve without constant rewriting of applications. Relational systems placed heavy demands on processing resources, and it was not until the mid 1980s that computing hardware became powerful enough to allow them to be widely deployed. By the early 1990s, however, relational systems were dominant for all large-scale data processing applications, and they remain dominant today (2012) except in niche areas. The dominant database language is the standard SQL for the Relational model, which has influenced database languages also for other data models.Because the relational model emphasizes search rather than navigation, it does not make relationships between different entities explicit in the form of pointers, but represents them rather using primary keys and foreign keys. While this is a good basis for a query language, it is less well suited as a modeling language. For this reason a different model, the Entity-relationship model which emerged shortly later (1976), gained popularity for database design.In the period since the 1970s database technology has kept pace with the increasing resources becoming available from the computing platform: notably the rapid increase in the capacity and speed (and reduction in price) of disk storage, and the increasing capacity of main memory. This has enabled ever larger databases and higher throughputs to be achieved.The rigidity of the relational model, in which all data is held in tables with a fixed structure of rows and columns, has increasingly been seen as a limitation when handling information that is richer or more varied in structure than the traditional 'ledger-book' data of corporate information systems: for example, document databases, engineering databases, multimedia databases, or databases used in the molecular sciences. Various attempts have been made to address this problem, many of them gathering under banners such as post-relational or NoSQL. Two developments of note are the Object database and the XML database. The vendors of relational databases have fought off competition from these newer models by extending the capabilities of their own products to support a wider variety of data types.1.3General-purpose DBMSA DBMS has evolved into a complex software system and its development typically requires thousands of person-years of development effort.[citation needed] Some general-purpose DBMSs, like Oracle, Microsoft SQL Server, and IBM DB2, have been undergoing upgrades for thirty years or more. General-purpose DBMSs aim to satisfy as many applications as possible, which typically makes them even more complex than special-purpose databases. However, the fact that they can be used "off the shelf", as well as their amortized cost over many applications and instances, makes them an attractive alternative (Vsone-time development) whenever they meet an application's requirements.Though attractive in many cases, a general-purpose DBMS is not always the optimal solution: When certain applications are pervasive with many operating instances, each with many users, a general-purpose DBMS may introduce unnecessary overhead and too large "footprint" (too large amount of unnecessary, unutilized software code). Such applications usually justify dedicated development.Typical examples are email systems, though they need to possess certain DBMS properties: email systems are built in a way that optimizes email messages handling and managing, and do not need significant portions of a general-purpose DBMS functionality.1.4Database machines and appliancesIn the 1970s and 1980s attempts were made to build database systems with integrated hardware and software. The underlying philosophy was that such integration would provide higher performance at lower cost. Examples were IBM System/38, the early offering of Teradata, and the Britton Lee, Inc. database machine. Another approach to hardware support for database management was ICL's CAFS accelerator, a hardware disk controller with programmable search capabilities. In the long term these efforts were generally unsuccessful because specialized database machines could not keep pace with the rapid development and progress of general-purpose computers. Thus most database systems nowadays are software systems running on general-purpose hardware, using general-purpose computer data storage. However this idea is still pursued for certain applications by some companies like Netezza and Oracle (Exadata).1.5Database researchDatabase research has been an active and diverse area, with many specializations, carried out since the early days of dealing with the database concept in the 1960s. It has strong ties with database technology and DBMS products. Database research has taken place at research and development groups of companies (e.g., notably at IBM Research, who contributed technologies and ideas virtually to any DBMS existing today), research institutes, and Academia. Research has been done both through Theory and Prototypes. The interaction between research and database related product development has been very productive to the database area, and many related key concepts and technologies emerged from it. Notable are the Relational and the Entity-relationship models, the Atomic transaction concept and related Concurrency control techniques, Query languages and Query optimization methods, RAID, and more. Research has provided deep insight to virtually all aspects of databases, though not always has been pragmatic, effective (and cannot and should not always be: research is exploratory in nature, and not always leads to accepted or useful ideas). Ultimately market forces and real needs determine the selection of problem solutions and related technologies, also among those proposed by research. However, occasionally, not the best and most elegant solution wins (e.g., SQL). Along their history DBMSs and respective databases, to a great extent, have been the outcome of such research, while real product requirements and challenges triggered database research directions and sub-areas.The database research area has several notable dedicated academic journals (e.g., ACM Transactions on Database Systems-TODS, Data and Knowledge Engineering-DKE, and more) and annual conferences (e.g., ACM SIGMOD, ACM PODS, VLDB, IEEE ICDE, and more), as well as an active and quite heterogeneous (subject-wise) research community all over the world.1.6Database architectureDatabase architecture (to be distinguished from DBMS architecture; see below) may be viewed, to some extent, as an extension of Data modeling. It is used to conveniently answer requirements of different end-users from a same database, as well as for other benefits. For example, a financial department of a company needs the payment details of all employees as part of the company's expenses, but not other many details about employees, that are the interest of the human resources department. Thus different departments need different views of the company's database, that both include the employees' payments, possibly in a different level of detail (and presented in different visual forms). To meet such requirement effectively database architecture consists of three levels: external, conceptual and internal. Clearly separating the three levels was a major feature of the relational database model implementations that dominate 21st century databases.[13]The external level defines how each end-user type understands the organization of its respective relevant data in the database, i.e., the different needed end-user views.A single database can have any number of views at the external level.The conceptual level unifies the various external views into a coherent whole, global view.[13] It provides the common-denominator of all the external views. It comprises all the end-user needed generic data, i.e., all the data from which any view may be derived/computed. It is provided in the simplest possible way of such generic data, and comprises the back-bone of the database. It is out of the scope of the various database end-users, and serves database application developers and defined by database administrators that build the database.The Internal level (or Physical level) is as a matter of fact part of the database implementation inside a DBMS (see Implementation section below). It is concerned with cost, performance, scalability and other operational matters. It deals with storage layout of the conceptual level, provides supporting storage-structures like indexes, to enhance performance, and occasionally stores data of individual views (materialized views), computed from generic data, if performance justification exists for such redundancy. It balances all the external views' performance requirements, possibly conflicting, in attempt to optimize the overall database usage by all its end-uses according to the database goals and priorities.All the three levels are maintained and updated according to changing needs by database administrators who often also participate in the database design.The above three-level database architecture also relates to and being motivated by the concept of data independence which has been described for long time as a desired database property and was one of the major initial driving forces of the Relational model. In the context of the above architecture it means that changes made at a certain level do not affect definitions and software developed with higher level interfaces, and are being incorporated at the higher level automatically. For example, changes in the internal level do not affect application programs written using conceptual level interfaces, which saves substantial change work that would be needed otherwise.In summary, the conceptual is a level of indirection between internal and external. On one hand it provides a common view of the database, independent of different external view structures, and on the other hand it is uncomplicated by details of how the data is stored or managed (internal level). In principle every level, and even every external view, can be presented by a different data model. In practice usually a given DBMS uses the same data model for both the external and the conceptual levels (e.g., relational model). The internal level, which is hidden inside the DBMS and depends on its implementation (see Implementation section below), requires a different levelof detail and uses its own data structure types, typically different in nature from the structures of the external and conceptual levels which are exposed to DBMS users (e.g., the data models above): While the external and conceptual levels are focused on and serve DBMS users, the concern of the internal level is effective implementation details.中文译文:数据库1.1 数据库的概念数据库的概念已经演变自1960年以来,以缓解日益困难,在设计,建设,维护复杂的信息系统(通常与许多并发的最终用户,并用大量不同的数据)。

计算机专业外文资料翻译----微机发展简史

计算机专业外文资料翻译----微机发展简史

附录外文文献及翻译Progress in computersThe first stored program computers began to work around 1950. The one we built in Cambridge, the EDSAC was first used in the summer of 1949.These early experimental computers were built by people like myself with varying backgrounds. We all had extensive experience in electronic engineering and were confident that that experience would standus in good stead. This proved true, although we had some new things to learn. The most important of these was that transients must be treated correctly; what would cause a harmless flash on the screen of a television set could lead to a serious error in a computer.As far as computing circuits were concerned, we found ourselves with an embarrass de riches. For example, we could use vacuum tube diodes for gates as we did in the EDSAC or pentodes with control signals on both grids, a system widely used elsewhere. This sort of choice persisted and the term famillogic came into use. Those who have worked in the computer field will remember TTL, ECL and CMOS. Of these, CMOS has now become dominant.In those early years, the IEE was still dominated by power engineering and we had to fight a number of major battles in order to get radio engineering along with the rapidly developing subject of electronics. dubbed in the IEE light current electrical engineering. properlyrecognized as an activity in its own right. I remember that we had some difficulty in organizing a co nference because the power engineers‟ ways of doing things were not our ways. A minor source of irritation was that all IEE published papers were expected to start with a lengthy statement of earlier practice, something difficult to do when there was no earlier practiceConsolidation in the 1960sBy the late 50s or early 1960s, the heroic pioneering stage was over and the computer field was starting up in real earnest. The number of computers in the world had increased and they were much more reliable than the very early ones . To those years we can ascribe the first steps in high level languages and the first operating systems. Experimental time-sharing was beginning, and ultimately computer graphics was to come along.Above all, transistors began to replace vacuum tubes. This change presented a formidable challenge to the engineers of the day. They had to forget what they knew about circuits and start again. It can only be said that they measured up superbly well to the challenge and that the change could not have gone more smoothly.Soon it was found possible to put more than one transistor on the same bit of silicon, and this was the beginning of integrated circuits. As time went on, a sufficient level of integration was reached for one chip to accommodate enough transistors for a small number of gates or flip flops. This led to a range of chips known as the 7400 series. The gates and flip flops were independent of one another and each had its own pins. They could be connected by off-chip wiring to make a computer or anything else.These chips made a new kind of computer possible. It was called a minicomputer. It was something less that a mainframe, but still very powerful, and much more affordable. Instead of having one expensive mainframe for the whole organization, a business or a university was able to have a minicomputer for each major department.Before long minicomputers began to spread and become more powerful. The world was hungry for computing power and it had been very frustrating for industry not to be able to supply it on the scalerequired and at a reasonable cost. Minicomputers transformed the situation.The fall in the cost of computing did not start with the minicomputer; it had always been that way. This was what I meant when I referred in my abstract to inflation in the computer industry …going the other way‟. As time goes on people get more for their money, not less.Research in Computer Hardware.The time that I am describing was a wonderful one for research in computer hardware. The user of the 7400 series could work at the gate and flip-flop level and yet the overall level of integration was sufficient to give a degree of reliability far above that of discreet transistors. The researcher, in a university orelsewhere, could build any digital device that a fertile imagination could conjure up. In the Computer Laboratory we built the Cambridge CAP, a full-scaleminicomputer with fancy capability logic.The 7400 series was still going strong in the mid 1970s and was used for the Cambridge Ring, a pioneering wide-band local area network. Publication of the design study for the Ring came just before the announcement of the Ethernet. Until these two systems appeared, users had mostly been content with teletype-based local area networks. Rings need high reliability because, as the pulses go repeatedly round the ring, they must be continually amplified and regenerated. It was the high reliability provided by the 7400 series of chips that gave us the courage needed to embark on the project for the Cambridge Ring.The RISC Movement and Its AftermathEarly computers had simple instruction sets. As time went on designers of commercially available machines added additional features which they thought would improve performance. Few comparative measureme nts were done and on the whole the choice of features depended upon the designer‟s intuition.In 1980, the RISC movement that was to change all this broke on the world. The movement opened with a paper by Patterson and ditzy entitled The Case for the Reduced Instructions Set Computer.Apart from leading to a striking acronym, this title conveys little of the insights into instruction set design which went with the RISC movement, in particular the way it facilitated pipelining, a system whereby several instructions may be in different stages of execution within the processor at the same time. Pipelining was not new, but it was new for small computersThe RISC movement benefited greatly from methods which had recently become available for estimating the performance to be expected from a computer design without actually implementing it. I refer to the use of a powerful existing computer to simulate the new design. By the use of simulation, RISC advocates were able to predict with some confidence that a good RISC design would be able to out-perform the best conventional computers using the same circuit technology. This prediction was ultimately born out in practice.Simulation made rapid progress and soon came into universal use by computer designers. In consequence, computer design has become more of a science and less of an art. Today, designers expect to have a roomful of, computers available to do their simulations, not just one. They refer to such a roomful by the attractive name of computer farm.The x86 Instruction SetLittle is now heard of pre-RISC instruction sets with one major exception, namely that of the Intel 8086 and its progeny, collectively referred to as x86. This has become the dominant instruction set and the RISC instruction sets that originally had a considerable measure of success are having to put up a hard fight for survival.This dominance of x86 disappoints people like myself who come from the research wings. both academic and industrial. of the computer field. No doubt, business considerations have a lot to do with the survival of x86, but there are other reasons as well. However much we research oriented people would liketo think otherwise. high level languages have not yet eliminated the use of machine code altogether. We need to keep reminding ourselves that there is much to be said for strict binary compatibility with previous usage when that can be attained. Nevertheless, things might have been different if Intel‟s major attempt to produce a good RISC chip had been more successful. I am referring to the i860 (not the i960, which was something different). In many ways the i860 was an excellent chip, but its software interface did not fit it to be used in aworkstation.There is an interesting sting in the tail of this apparently easy triumph of the x86 instruction set. It proved impossible to match the steadily increasing speed of RISC processors by direct implementation ofthe x86 instruction set as had been done in the past. Instead, designers took a leaf out of the RISC book; although it is not obvious, on the surface, a modern x86 processor chip contains hidden within it a RISC-style processor with its own internal RISC coding. The incoming x86 code is, after suitable massaging, converted into this internal code and handed over to the RISC processor where the critical execution is performed. In this summing up of the RISC movement, I rely heavily on the latest edition of Hennessy and Patterson‟s books on computer design as my supporting authority; see in particular Computer Architecture, third edition, 2003, pp 146, 151-4, 157-8.The IA-64 instruction set.Some time ago, Intel and Hewlett-Packard introduced the IA-64 instruction set. This was primarily intended to meet a generally recognized need for a 64 bit address space. In this, it followed the lead of the designers of the MIPS R4000 and Alpha. However one would have thought that Intel would have stressed compatibility with the x86; the puzzle is that they did the exact opposite.Moreover, built into the design of IA-64 is a feature known as predication which makes it incompatible in a major way with all other instruction sets. In particular, it needs 6 extra bits with each instruction. This upsets the traditional balance between instruction word length and information content, and it changes significantly the brief of the compiler writer.In spite of having an entirely new instruction set, Intel made the puzzling claim that chips based on IA-64 would be compatible with earlier x86 chips. It was hard to see exactly what was meant.Chips for the latest IA-64 processor, namely, the Itanium, appear to have special hardware for compatibility. Even so, x86 code runs very slowly.Because of the above complications, implementation of IA-64 requires a larger chip than is required for more conventional instruction sets. This in turn implies a higher cost. Such at any rate, is the received wisdom, and, as a general principle, it was repeated as such by Gordon Moore when he visited Cambridge recently to open the Betty and Gordon Moore Library. I have, however, heard it said that the matter appears differently from within Intel. This I do not understand. But I am very ready to admit that I am completely out of my depth as regards the economics of the semiconductor industry.Shortage of ElectronsAlthough shortage of electrons has not so far appeared as an obvious limitation, in the long term it may become so. Perhaps this is where the exploitation of non-conventional CMOS will lead us. However, some interesting work has been done. notably by HuronAmend and his team working in the Cavendish Laboratory. on the direct development of structures in which a single electron more or less makes the difference between a zero and a one. However very little progress has been made towards practical devices that could lead to the construction of a computer. Even with exceptionally good luck, many tens of years must inevitably elapse before a working computer based on single electron effects can be contemplated.微机发展简史第一台存储程序的计算开始出现于1950前后,它就是1949年夏天在剑桥大学,我们创造的延迟存储自动电子计算机(EDSAC)。

计算机专业中英文翻译(外文翻译、文献翻译)

计算机专业中英文翻译(外文翻译、文献翻译)

英文参考文献及翻译Linux - Operating system of cybertimesThough for a lot of people , regard Linux as the main operating system to make up huge work station group, finish special effects of " Titanic " make , already can be regarded as and show talent fully. But for Linux, this only numerous news one of. Recently, the manufacturers concerned have announced that support the news of Linux to increase day by day, users' enthusiasm to Linux runs high unprecedentedly too. Then, Linux only have operating system not free more than on earth on 7 year this piece what glamour, get the favors of such numerous important software and hardware manufacturers as the masses of users and Orac le , Informix , HP , Sybase , Corel , Intel , Netscape , Dell ,etc. , OK?1.The background of Linux and characteristicLinux is a kind of " free (Free ) software ": What is called free,mean users can obtain the procedure and source code freely , and can use them freely , including revise or copy etc.. It is a result of cybertimes, numerous technical staff finish its research and development together through Inte rnet, countless user is it test and except fault , can add user expansion function that oneself make conveniently to participate in. As the most outstanding one in free software, Linux has characteristic of the following:(1)Totally follow POSLX standard, expand the network operatingsystem of supporting all AT&T and BSD Unix characteristic. Because of inheritting Unix outstanding design philosophy , and there are clean , stalwart , high-efficient and steady kernels, their all key codes are finished by Li nus Torvalds and other outstanding programmers, without any Unix code of AT&T or Berkeley, so Linu x is not Unix, but Linux and Unix are totally compatible.(2)Real many tasks, multi-user's system, the built-in networksupports, can be with such seamless links as NetWare , Windows NT , OS/2 , Unix ,etc.. Network in various kinds of Unix it tests to be fastest in comparing and assess efficiency. Support such many kinds of files systems as FAT16 , FAT32 , NTFS , Ex t2FS , ISO9600 ,etc. at the same time .(3) Can operate it in many kinds of hardwares platform , including such processors as Alpha , SunSparc , PowerPC , MIPS ,etc., to various kinds of new-type peripheral hardwares, can from distribute on global numerous programmer there getting support rapidly too.(4) To that the hardware requires lower, can obtain very good performance on more low-grade machine , what deserves particular mention is Linux outstanding stability , permitted " year " count often its running times.2.Main application of Linux At present,Now, the application of Linux mainly includes:(1) Internet/Intranet: This is one that Linux was used most at present, it can offer and include Web server , all such Inter net services as Ftp server , Gopher server , SMTP/POP3 mail server , Proxy/Cache server , DNS server ,etc.. Linux kernel supports IPalias , PPP and IPtunneling, these functions can be used for setting up fictitious host computer , fictitious service , VPN (fictitious special-purpose network ) ,etc.. Operating Apache Web server on Linux mainly, the occupation rate of market in 1998 is 49%, far exceeds the sum of such several big companies as Microsoft , Netscape ,etc..(2) Because Linux has outstanding networking ability , it can be usedin calculating distributedly large-scaly, for instance cartoon making , scientific caculation , database and file server ,etc..(3) As realization that is can under low platform fullness of Unix that operate , apply at all levels teaching and research work of universities and colleges extensively, if Mexico government announce middle and primary schools in the whole country dispose Linux and offer Internet service for student already.(4) Tabletop and handling official business appliedly. Application number of people of in this respect at present not so good as Windows of Microsoft far also, reason its lie in Lin ux quantity , desk-top of application software not so good as Windows application far not merely,because the characteristic of the freedom software makes it not almost have advertisement that support (though the function of Star Office is not second to MS Office at the same time, but there are actually few people knowing).3.Can Linux become a kind of major operating system?In the face of the pressure of coming from users that is strengthened day by day, more and more commercial companies transplant its application to Linux platform, comparatively important incident was as follows, in 1998 ①Compaq and HP determine to put forward user of requirement truss up Linux at their servers , IBM and Dell promise to offer customized Linux system to user too. ②Lotus announce, Notes the next edition include one special-purpose edition in Linux. ③Corel Company transplants its famous WordPerfect to on Linux, and free issue. Corel also plans to move the other figure pattern process products to Linux platform completely.④Main database producer: Sybase , Informix , Oracle , CA , IBM have already been transplanted one's own database products to on Linux, or has finished Beta edition, among them Oracle and Informix also offer technical support to their products.4.The gratifying one is, some farsighted domestic corporations have begun to try hard to change this kind of current situation already. Stone Co. not long ago is it invest a huge sum of money to claim , regard Linux as platform develop a Internet/Intranet solution, regard this as the core and launch Stone's system integration business , plan to set up nationwide Linux technical support organization at the same time , take the lead to promote the freedom software application and development in China. In addition domestic computer Company , person who win of China , devoted to Linux relevant software and hardware application of system popularize too. Is it to intensification that Linux know , will have more and more enterprises accede to the ranks that Linux will be used with domestic every enterprise to believe, more software will be planted in Linux platform. Meanwhile, the domestic university should regard Linux as the original version and upgrade already existing Unix content of courses , start with analysing the source code and revising the kernel and train a large number of senior Linux talents, improve our country's own operating system. Having only really grasped the operating system, the software industry of our country could be got rid of and aped sedulously at present, the passive state led by the nose byothers, create conditions for revitalizing the software industry of our country fundamentally.中文翻译Linux—网络时代的操作系统虽然对许多人来说,以Linux作为主要的操作系统组成庞大的工作站群,完成了《泰坦尼克号》的特技制作,已经算是出尽了风头。

计算机外文翻译(完整)

计算机外文翻译(完整)

计算机外⽂翻译(完整)毕业设计(论⽂)外⽂资料翻译专业:计算机科学与技术姓名:王成明学号:06120186外⽂出处:The History of the Internet附件: 1.外⽂原⽂ 2.外⽂资料翻译译⽂;附件1:外⽂原⽂The History of the InternetThe Beginning - ARPAnetThe Internet started as a project by the US government. The object of the project was to create a means of communications between long distance points, in the event of a nation wide emergency or, more specifically, nuclear war. The project was called ARPAnet, and it is what the Internet started as. Funded specifically for military communication, the engineers responsible for ARPANet had no idea of the possibilities of an "Internet."By definition, an 'Internet' is four or more computers connected by a network.ARPAnet achieved its network by using a protocol called TCP/IP. The basics around this protocol was that if information sent over a network failed to get through on one route, it would find another route to work with, as well as establishing a means for one computer to "talk" to another computer, regardless of whether it was a PC or a Macintosh.By the 80's ARPAnet, just years away from becoming the more well known Internet, had 200 computers. The Defense Department, satisfied with ARPAnets results, decided to fully adopt it into service, and connected many military computers and resources into the network. ARPAnet then had 562 computers on its network. By the year 1984, it had over 1000 computers on its network.In 1986 ARPAnet (supposedly) shut down, but only the organization shut down, and the existing networks still existed between the more than 1000 computers. It shut down due to a failied link up with NSF, who wanted to connect its 5 countywide super computers into ARPAnet.With the funding of NSF, new high speed lines were successfully installed at line speeds of 56k (a normal modem nowadays) through telephone lines in 1988. By that time, there were 28,174 computers on the (by then decided) Internet. In 1989 there were 80,000 computers on it. By 1989, there were290,000.Another network was built to support the incredible number of people joining. It was constructed in 1992.Today - The InternetToday, the Internet has become one of the most important technological advancements in the history of humanity. Everyone wants to get 'on line' to experience the wealth of information of the Internet. Millions of people now use the Internet, and it's predicted that by the year 2003 every single person on the planet will have Internet access. The Internet has truly become a way of life in our time and era, and is evolving so quickly its hard to determine where it will go next, as computer and network technology improve every day.HOW IT WORKS:It's a standard thing. People using the Internet. Shopping, playing games,conversing in virtual Internet environments.The Internet is not a 'thing' itself. The Internet cannot just "crash." It functions the same way as the telephone system, only there is no Internet company that runs the Internet.The Internet is a collection of millioins of computers that are all connected to each other, or have the means to connect to each other. The Internet is just like an office network, only it has millions of computers connected to it.The main thing about how the Internet works is communication. How does a computer in Houston know how to access data on a computer in Tokyo to view a webpage?Internet communication, communication among computers connected to the Internet, is based on a language. This language is called TCP/IP. TCP/IP establishes a language for a computer to access and transmit data over the Internet system.But TCP/IP assumes that there is a physical connecetion between onecomputer and another. This is not usually the case. There would have to be a network wire that went to every computer connected to the Internet, but that would make the Internet impossible to access.The physical connection that is requireed is established by way of modems,phonelines, and other modem cable connections (like cable modems or DSL). Modems on computers read and transmit data over established lines,which could be phonelines or data lines. The actual hard core connections are established among computers called routers.A router is a computer that serves as a traffic controller for information.To explain this better, let's look at how a standard computer might viewa webpage.1. The user's computer dials into an Internet Service Provider (ISP). The ISP might in turn be connected to another ISP, or a straight connection into the Internet backbone.2. The user launches a web browser like Netscape or Internet Explorer and types in an internet location to go to.3. Here's where the tricky part comes in. First, the computer sends data about it's data request to a router. A router is a very high speed powerful computer running special software. The collection of routers in the world make what is called a "backbone," on which all the data on the Internet is transferred. The backbone presently operates at a speed of several gigabytes per-second. Such a speed compared to a normal modem is like comparing the heat of the sun to the heat of an ice-cube.Routers handle data that is going back and forth. A router puts small chunks of data into packages called packets, which function similarly to envelopes. So, when the request for the webpage goes through, it uses TCP/IP protocols to tell the router what to do with the data, where it's going, and overall where the user wants to go.4. The router sends these packets to other routers, eventually leadingto the target computer. It's like whisper down the lane (only the information remains intact).5. When the information reaches the target web server, the webserver then begins to send the web page back. A webserver is the computer where the webpage is stored that is running a program that handles requests for the webpage and sends the webpage to whoever wants to see it.6. The webpage is put in packets, sent through routers, and arrive at the users computer where the user can view the webpage once it is assembled.The packets which contain the data also contain special information that lets routers and other computers know how to reassemble the data in the right order.With millions of web pages, and millions of users, using the Internet is not always easy for a beginning user, especially for someone who is not entirely comfortale with using computers. Below you can find tips tricks and help on how to use main services of the Internet.Before you access webpages, you must have a web browser to actually be able to view the webpages. Most Internet Access Providers provide you with a web browser in the software they usually give to customers; you. The fact that you are viewing this page means that you have a web browser. The top two use browsers are Netscape Communicator and Microsoft Internet Explorer. Netscape can be found at /doc/bedc387343323968011c9268.html and MSIE can be found at /doc/bedc387343323968011c9268.html /ie.The fact that you're reading this right now means that you have a web browser.Next you must be familiar with actually using webpages. A webpage is a collection of hyperlinks, images, text, forms, menus, and multimedia. To "navigate" a webpage, simply click the links it provides or follow it's own instructions (like if it has a form you need to use, it will probably instruct you how to use it). Basically, everything about a webpage is made to be self-explanetory. That is the nature of a webpage, to be easily navigatable."Oh no! a 404 error! 'Cannot find web page?'" is a common remark made by new web-users.Sometimes websites have errors. But an error on a website is not the user's fault, of course.A 404 error means that the page you tried to go to does not exist. This could be because the site is still being constructed and the page hasn't been created yet, or because the site author made a typo in the page. There's nothing much to do about a 404 error except for e-mailing the site administrator (of the page you wanted to go to) an telling him/her about the error.A Javascript error is the result of a programming error in the Javascript code of a website. Not all websites utilize Javascript, but many do. Javascript is different from Java, and most browsers now support Javascript. If you are using an old version of a web browser (Netscape 3.0 for example), you might get Javascript errors because sites utilize Javascript versions that your browser does not support. So, you can try getting a newer version of your web browser.E-mail stands for Electronic Mail, and that's what it is. E-mail enables people to send letters, and even files and pictures to each other.To use e-mail, you must have an e-mail client, which is just like a personal post office, since it retrieves and stores e-mail. Secondly, you must have an e-mail account. Most Internet Service Providers provide free e-mail account(s) for free. Some services offer free e-mail, like Hotmail, and Geocities.After configuring your e-mail client with your POP3 and SMTP server address (your e-mail provider will give you that information), you are ready to receive mail.An attachment is a file sent in a letter. If someone sends you an attachment and you don't know who it is, don't run the file, ever. It could be a virus or some other kind of nasty programs. You can't get a virus justby reading e-mail, you'll have to physically execute some form of program for a virus to strike.A signature is a feature of many e-mail programs. A signature is added to the end of every e-mail you send out. You can put a text graphic, your business information, anything you want.Imagine that a computer on the Internet is an island in the sea. The sea is filled with millions of islands. This is the Internet. Imagine an island communicates with other island by sending ships to other islands and receiving ships. The island has ports to accept and send out ships.A computer on the Internet has access nodes called ports. A port is just a symbolic object that allows the computer to operate on a network (or the Internet). This method is similar to the island/ocean symbolism above.Telnet refers to accessing ports on a server directly with a text connection. Almost every kind of Internet function, like accessing web pages,"chatting," and e-mailing is done over a Telnet connection.Telnetting requires a Telnet client. A telnet program comes with the Windows system, so Windows users can access telnet by typing in "telnet" (without the "'s) in the run dialog. Linux has it built into the command line; telnet. A popular telnet program for Macintosh is NCSA telnet.Any server software (web page daemon, chat daemon) can be accessed via telnet, although they are not usually meant to be accessed in such a manner. For instance, it is possible to connect directly to a mail server and check your mail by interfacing with the e-mail server software, but it's easier to use an e-mail client (of course).There are millions of WebPages that come from all over the world, yet how will you know what the address of a page you want is?Search engines save the day. A search engine is a very large website that allows you to search it's own database of websites. For instance, if you wanted to find a website on dogs, you'd search for "dog" or "dogs" or "dog information." Here are a few search-engines.1. Altavista (/doc/bedc387343323968011c9268.html ) - Web spider & Indexed2. Yahoo (/doc/bedc387343323968011c9268.html ) - Web spider & Indexed Collection3. Excite (/doc/bedc387343323968011c9268.html ) - Web spider & Indexed4. Lycos (/doc/bedc387343323968011c9268.html ) - Web spider & Indexed5. Metasearch (/doc/bedc387343323968011c9268.html ) - Multiple searchA web spider is a program used by search engines that goes from page to page, following any link it can possibly find. This means that a search engine can literally map out as much of the Internet as it's own time and speed allows for.An indexed collection uses hand-added links. For instance, on Yahoo's site. You can click on Computers & the Internet. Then you can click on Hardware. Then you can click on Modems, etc., and along the way through sections, there are sites available which relate to what section you're in.Metasearch searches many search engines at the same time, finding the top choices from about 10 search engines, making searching a lot more effective.Once you are able to use search engines, you can effectively find the pages you want.With the arrival of networking and multi user systems, security has always been on the mind of system developers and system operators. Since the dawn of AT&T and its phone network, hackers have been known by many, hackers who find ways all the time of breaking into systems. It used to not be that big of a problem, since networking was limited to big corporate companies or government computers who could afford the necessary computer security.The biggest problem now-a-days is personal information. Why should you be careful while making purchases via a website? Let's look at how the internet works, quickly.The user is transferring credit card information to a webpage. Looks safe, right? Not necessarily. As the user submits the information, it is being streamed through a series of computers that make up the Internet backbone.The information is in little chunks, in packages called packets. Here's the problem: While the information is being transferred through this big backbone, what is preventing a "hacker" from intercepting this data stream at one of the backbone points?Big-brother is not watching you if you access a web site, but users should be aware of potential threats while transmitting private information. There are methods of enforcing security, like password protection, an most importantly, encryption.Encryption means scrambling data into a code that can only be unscrambled on the "other end." Browser's like Netscape Communicator and Internet Explorer feature encryption support for making on-line transfers. Some encryptions work better than others. The most advanced encryption system is called DES (Data Encryption Standard), and it was adopted by the US Defense Department because it was deemed so difficult to 'crack' that they considered it a security risk if it would fall into another countries hands.A DES uses a single key of information to unlock an entire document. The problem is, there are 75 trillion possible keys to use, so it is a highly difficult system to break. One document was cracked and decoded, but it was a combined effort of14,000 computers networked over the Internet that took a while to do it, so most hackers don't have that many resources available.附件2:外⽂资料翻译译⽂Internet的历史起源——ARPAnetInternet是被美国政府作为⼀项⼯程进⾏开发的。

计算机系外文翻译--历史的计算

计算机系外文翻译--历史的计算

毕业设计(论文)外文资料翻译系别计算机信息与技术系专业计算机科学与技术班级姓名学号外文出处附件 1. 原文; 2. 译文2012年3月History of computingMain article: History of computing hardwareThe first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.Limited-function early computersThe Jacquard loom, on display at the Museum of Science and Industry in Manchester, England, was one of the first programmable devices.The history of the modern computer begins with two separate technologies, automated calculation and programmability, but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. A few devices are worth mentioning though, like some mechanical aids to computing, which were very successful and survived for centuries until the advent of the electronic calculator, like the Sumerian abacus, designed around 2500 BC of which a descendant won a speed competition against a modern desk calculating machine in Japan in 1946, the slide rules, invented in the 1620s, which were carried on five Apollo space missions, including to the moon and arguably the astrolabe and the Antikythera mechanism, an ancient astronomical computer built by the Greeks around 80 BC. The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.Around the end of the 10th century, the French monk Gerbert d'Aurillac brought back from Spain the drawings of a machine invented by the Moors that answered either Yes or No to the questions it was asked. Again in the 13th century, the monks Albertus Magnus and Roger Bacon built talking androids without any further development.In 1642, the Renaissance saw the invention of the mechanical calculator, a device that could perform all four arithmetic operations without relying on human intelligence. The mechanical calculator was at the root of the development ofcomputers in two separate ways. Initially, it was in trying to develop more powerful and more flexible calculators that the computer was first theorized by Charles Babbage and then developed. Secondly, development of a low-cost electronic calculator, successor to the mechanical calculator, resulted in the development by Intel of the first commercially available microprocessor integrated circuit.First general-purpose computersIn 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of punched paper cards as a template which allowed his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer, his analytical engine. Limited finances and Babbage's inability to resist tinkering with the design meant that the device was never completed ; nevertheless his son, Henry Babbage, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906. This machine was given to the Science museum in South Kensington in 1910.In the late 1880s, Herman Hollerith invented the recording of data on a machine-readable medium. Earlier uses of machine-readable media had been for control, not data. "After some initial trials with paper tape, he settled on punched cards ..." To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith's company, which later became the core of IBM. By the end of the 19th century a number of ideas and technologies, that would later prove useful in the realization of practical computers, had begun to appear: Boolean algebra, the vacuum tube (thermionic valve), punched cards and tape, and the teleprinter.During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digitalcomputers.Alan Turing is widely regarded as the father of modern computer science. In 1936 Turing provided an influential formalisation of the concept of the algorithm and computation with the Turing machine, providing a blueprint for the electronic digital computer. Of his role in the creation of the modern computer, Time magazine in naming Turing one of the 100 most influential people of the 20th century, states: "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine".EDSAC was one of the first computers to implement the stored-program (von Neumann) architecture.Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging.The Atanasoff–Berry Computer (ABC) was the world's first electronic digital computer, albeit not programmable. Atanasoff is considered to be one of the fathers of the computer.Conceived in 1937 by Iowa State College physics professor John Atanasoff, and built with the assistance of graduate student Clifford Berry, the machine was not programmable, being designed only to solve systems of linear equations. The computer did employ parallel computation. A 1973 court ruling in a patent dispute found that the patent for the 1946 ENIAC computer derived from the Atanasoff–Berry Computer.The first program-controlled computer was invented by Konrad Zuse, who built the Z3, an electromechanical computing machine, in 1941. The first programmable electronic computer was the Colossus, built in 1943 by Tommy Flowers.George Stibitz is internationally recognized as a father of the modern digital computer. While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the "Model K" (for "kitchen table", on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability.A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult.Notable achievements include. Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.The non-programmable Atanasoff–Berry Computer (commenced in 1937, completed in 1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory. The use of regenerative memory allowed it to be much more compact than its peers (being approximately the size of a large desk or workbench), since intermediate results could be stored and then fed back into the same set of computation elements.The secret British Colossus computers (1943), which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.The U.S. Army's Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.Stored-program architectureReplica of the Small-Scale Experimental Machine (SSEM), the world's first stored-program computer, at the Museum of Science and Industry in Manchester, EnglandSeveral developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the "stored-program architecture" or von Neumann architecture. This design was first formally described by John von Neumann in the paper First Draft of a Report on the EDV AC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture commenced around this time, the first of which was completed in 1948 at the University of Manchester in England, the Manchester Small-Scale Experimental Machine (SSEM or "Baby"). The Electronic Delay Storage Automatic Calculator(EDSAC), completed a year after the SSEM at Cambridge University, was the first practical, non-experimental implementation of the stored-program design and was put to use immediately for research work at the university. Shortly thereafter, the machine originally described by von Neumann's paper—EDV AC—was completed but did not see full-time use for an additional two years.Nearly all modern computers implement some form of the stored-program architecture, making it the single trait by which the word "computer" is now defined. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture.Beginning in the 1950s, Soviet scientists Sergei Sobolev and Nikolay Brusentsov conducted research on ternary computers, devices that operated on a base three numbering system of ?1, 0, and 1 rather than the conventional binary numbering system upon which most computers are based. They designed the Setun, a functional ternary computer, at Moscow State University. The device was put into limited production in the Soviet Union, but supplanted by the more common binary architecture.Semiconductors and microprocessorsComputers using vacuum tubes as their electronic elements were in use throughout the 1950s, but by the 1960s had been largely replaced by semiconductor transistor-based machines, which were smaller, faster, cheaper to produce, required less power, and were more reliable. The first transistorised computer was demonstrated at the University of Manchester in 1953. In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. By the late 1970s, many products such as video recorders contained dedicated computers called microcontrollers, and they started to appear as a replacement to mechanical controls in domestic appliances such as washing machines. The 1980s witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household.Modern smartphones are fully programmable computers in their own right, and as of 2009 may well be the most common form of such computers in existenc.历史的计算主要文章:计算机硬件的历史在第一次使用“计算机”这个词被记录在1613年,指的是对一个人进行了计算,或计算,与词的意思相同,直到继续20世纪中期。

【计算机专业文献翻译】信息系统的管理

【计算机专业文献翻译】信息系统的管理
基本上每一台计算机都能连接到网络中,一台计算机要么是客户端,要么就是服务器。服务器更具强大和区别性,因为它存储了网络中其他机器需要使用的数据。个人计算机的客户端在需要数据的时候随时都可以访问服务器。网络中既是服务器又是客户端的计算机称作点对点网络。
传播媒体必须经过仔细选择,平衡每个媒体的优点和缺点,这个选择决定网络的速度。改变一个已经安装好的网络媒体通常非常昂贵。最实用的传播媒体是电缆,光纤,广播,光,红外线。
本科生毕业设计(论文)外文资料译文
(2009届)
论文题目
基于Javamail的邮件收发系统
学生姓名
学号
专业
计算机科学与技术
班级
指导教师
职称
讲师、副教授
填表日期
2008年 12月 10 日
信息科学与工程学院教务科制
外文资料翻译(译文不少于2000汉字)
1.所译外文资料:信息系统的管理Managing Information Systems
数据共享是网络的重要应用之一。网络可以共享交易数据,搜索和查询数据,信息,公告板,日历,团队和个人信息数据,备份等。在交易的时候,连接一个公司的电脑的中央数据库包括现有库存信息和出售的数据信息。如果数据被储存在一个中央数据库中,搜查结果便可从中获取。电子邮件的发送已经成为同事之间最常用的信息共享的方式之一。
自从信号在空中传输后,广播,光以及红外线作为传播媒体已经不需要电缆。
传输能力,即一个传播媒体一次性传输的数据量,在不同的媒体中,材料不同,安装时付出的劳动不同,传输的能力有很大的区别。传播媒体有时候被合并,代替远地域之间的高速传播媒体,速度虽慢,但是成本低,在一幢大楼中进行信息传播。
连接设备包括网络连接卡NICS,或者在计算机和网络间进行传输和信号传递的局域网LAN卡。其他常用的设备连接不同的网络,特别是当一个网络使用不用的传输媒体的时候。使用一个对很多用户都开放的系统很重要,比如windows/NT,Office2000,Novell,UNIX.

计算机类毕业外文翻译---系统开发阶段

计算机类毕业外文翻译---系统开发阶段

计算机类毕业外文翻译The Phase to Develop the systemWith the society's development, the personal relationship is day by day intense. How enhances the personal relationship, reduces the management cost, the enhancement service level and pensonal competitive ability, is every one superintendent most matter of concern. More and more superintendents thought the implementation computer scientific style management solves this question.Management information systems (MIS), are information systems, typically computer based, that are used within an organization. World net described an information system as‖ a system consisting of the network of all communication channels used with an organization‖.Generally speaking, MIS involved the following parts:1 Conduct a Preliminary Investigation(1)What is the objective of the first phase of the SDLC?Attention: SDLC means Systems Development Life Cycle.The objectives of phase 1, preliminary investigation, are to conduct a preliminary analysis, propose alternative solutions, describe the costs and benefits of each solution, and submit a preliminary plan with recommendations. The problems are briefly identified and a few solutions are suggested. This phase is often called a feasibility study.(2)Conduct the preliminary analysisIn this step, you need to find out what the organization’s objectives are and to explore the nature and scope of the problems under study.Determine the organization’s objectives: Even if a problem pertains to only a small segment of the organization, you cannot study it in isolation. You need to find out what the overall objectives of the organization are and how groups and departments with in the organization interact. Then you need to examine the problem in that context.Determine the nature and scope of the problems: you may already have a sense of the nature and scope of a problem. However, with a fuller understanding of the goals of the organization, you can now take a closer look at the specifics. Is too much time being wasted on paperwork? On waiting for materials? On nonessential tasks? How pervasive is the problem within the organization? Outside of it? What people are most affected? And so on. Your reading and your interviews should give you a sense of the character of the problem.(3)Propose alternative solutionsIn delving into the organization’s objectives and the specific problems, you may have already discovered some solutions. Other possible solutions may be generated by interviewing people inside the organization, clients or customers, suppliers, and consultants and by studying what competitors are doing. With this data, you then have three choices. You can leave the system as is, improve it, or develop a new system.Leave the system as is: often, especially with paper-based or no technological systems, the problem really isn’t bad enough to justify the measures and expenditures required to get rid of it.Improve the system: sometimes changing a few key elements in the system upgrading to a new computer or new software, or doing a bit of employee retraining, for example will do the trick. Modifications might be introduced over several months, if the problem is no serious.Develop a new system: if the existing system is truly harmful to the organization, radical changes may be warranted. A new system would not mean just tinkering around the edges or introducing some new piece of hardware or software. It could mean changes in every part and at every level.(4)Describe costs and benefitsWhichever of the three alternatives is chose, it will have costs and benefits. In this step, you need to indicate what these are.The changes or absence of changes will have a price tag, of course, and you need to indicate what it is. Greater costs may result in greater benefits, which, in turn, may offer savings. The benefits may be both tangible—such as costly savings –and intangible—such as worker satisfaction. A process may be speeded up, streamlined through the elimination of unnecessary steps, or combined with other processes. Input errors or redundant output may be reduced. Systems and subsystems may be better integrated. Users may be happier with the system. Customers or suppliers may interact more efficiently with the system. Security may be improved. Costs may be cut.(5)Submit a preliminary planNow you need to wrap up all your findings in a written report, submitted to the executives(probably top managers) who are in a position to decide in which direction to proceed—make no changes, change a little, or change a lot—and how much money to allow the project. You should describe the potential solutions, costs, and benefits and indicate your recommendations. If management approves the feasibility study, then the systems analysis phase can begin.2 Do a Detailed Analysis of the System(1)What tools are used in the second phase of the SDLC to analyze data?The objectives of phase 2, systems analysis, are to gather data, analyze the data, and write a report. The present system is studied in depth, and new requirements are specified. Systems analysis describes what a system is already doing and what it should do to meet the needs of users. Systems design—the next phase—specifies how the system will accommodate the objective.In this second phase of the SDLC, you will follow the course prescribed by management on the basis of your phase/feasibility report. We are assuming what you have been directed to perform phase 2—to do a careful analysis of the existing system, in order to understand how the new system you propose would differ. This analysis will also consider how people’s positions and tasks will have to change if the new system is put into effect. In general, it involves a detailed study of: The information needs of the organization and all users;The actives, resources, and products or any present information systems;The information systems capabilities required to need the established information needs and user needs.(2)Gather dataIn gathering data, systems analysts use a handful of tools. Most of them not tem ply technical. They include written documents, interviews, questionnaires, observation, and sampling.Written documents: a great deal of what you need is probably available in the form of written documents, and so on. Documents are a good place to start because they tell you how things are or are supposed to be. These tools will also provide leads on people and areas to pursuer further.Interviews: interviews with managers, workers, clients, suppliers, and competitors will also give you insights. Interviews may be structured or unstructured.Questionnaires: questionnaires are useful for getting information for large groups of people when you can’t get around to interviewing everyone. Questionnaires may also yield more information if respondents can be anonymous. In addition, this tool is convenient, is inexpensive, and yields a lot of data. However, people may not return their forms, results can be ambiguous, and with anonymous questionnaires you’ll have no opportunity to follow up.Observation: no doubt you’ve sat in a coffee shop or on a park bench and just alone ―a person is watching‖. This can be a tool for analysis, too. Through observation you can see how people interact with one another and how paper moves through an organization. Observation can be non-participant or participant. If you are a non-participant observer, and people knew they are a participant observer, you may gain more insights by experiencing the conflicts and responsibilities of the people you are working with.(3)Analyze the dataOnce the data is gathered, you need to come to grips with it and analyze it. Many analytical tools, or modeling tools, are available. Modeling tools enables a systems analyst to present graphic representations of a system. Examples are CASE tools,data flow diagrams, systems flow charts, connectivity diagrams, grid charts, decision tables, and object-oriented analysis.For example, in analyzing the current system and preparing data flow diagrams, the systems analyst must also prepare a data dictionary, which is then used and expanded during all remaining phases of the SDLC. A data dictionary defines all the elements that make up the data flow. Among other things, it records what each data element is by name, how long it is, are where it is used, as well as any numerical values assigned to it. This information is usually entered into a data dictionary software program.The Phase: Design the System(4)At the conclusions of the third phase of the SDLC, what should have been created?The objectives of phase 3, systems design, are to do a preliminary design and then a detail and to write a report. In this third phase of the SDLC, you will essentially create a rough draft and then a detail draft of the proposed information system.(5)Do a preliminary designA preliminary design describes the general foundational capabilities of proposed information system. It reviews the system requirements and then considers major components of the system. Usually several alternative systems are considered, and the costs and the benefits of each are evaluated.Some tools that may be used in the preliminary design an the detail design are following:CASE tools: they are software programs that automate various activities of the SDLC in several phases. This screen is from one of their banking system tools. It shows a model for an A TM transaction. The purchaser of the CASE tool would enter details relative to the particular situation. This technology is intended to speed up to the process of developing systems and to improve the quality of the resulting systems.Project management software: it consists of programs used to plan, schedule, a control the people, costs, and resources required to complete a project on time.3 A detail designA detail design describes how a proposed information system will deliver the general capabilities in the preliminary design. The detail design usually considers the following parts of the system, in this order: output requirements, and system controls and backup.(1) Output requirements: the first thing to determine is what you want the system to produce. In this first step, the systems analyst determines what media the appearance or format of the output, such as headings, columns, and menus.(2) Input requirements: once you know the output, you can determine the inputs, here, too, you must define the type of input, such as keyboard or source data entry. You must determine in what form data will be input and how it will be checked for accuracy. You also need to figure out what volume of data the system can be allowed to take in.(3) Storage requirements: using the data dictionary as a quite, you need to define the files and databases in the information system. How will the files be organized? What kind of storage devices will be used? How will they interface with other storage devices inside and outside of the organization? What will be the volume of database activity?(4) Processing and networking requirements, what kind of computer or computers will be used to handle the processing? What kind of operating system and applications software will be used? Will the computer or computers be tied to others in a network? Exactly what operations will be performed on the input data to achieve the desired output information? What kinds of user interface are desired?(5) System controls backup: finally, you need to think about matters of security, privacy, and data accuracy. You need to prevent unauthorized users from breaking into the system, for example, and snooping in private files. You need to devise auditing procedures and to set up specifications for testing the new system. Finally, you need to institute automatic ways of backing up information and storing it else where in case the system fails or is destroyed.4 Develop/Acquire the System(1)What general tasks do systems analysts perform in the fourth phase of the SDLC?Systems development/acquisition, the systems analysts or others in the organization acquire the software, acquire thehardware, and then test the system. This phase begins once management has accepted the report containing the design and has‖green lighted‖the way to development. Depending on the size of the project, this phase will probably involve substantial expenditures of money and time. However, at the end you should have a workable system.(2)Acquire softwareDuring the design stage, the systems analyst may have had to address what is called the ―make-or-buy‖ decision; if not, that decision certainly cannot be avoided now. In the make-or-buy decision, you decide whether you have to create a program –have it custom-written—or buy it. Sometimes programmers decide they can buy an existing software package and modify it rather than write it from scratch.If you decide to create a new program, then the question is whether to use the organization’s own staff programmers or to hair outside contract programmers. Whichever way you go, the task could take months.(3)Acquire hardwareOnce the software has been chosen, the hardware to run it must be acquired or upgraded. It’s possible you will not need to obtain any new hardware. It’s also possible that the new hardware will cost millions of dollars and involve many items: models, and many other devices. The organization may prefer to lease rather than buy some equipment, especially since chip capability was traditionally doubled about every 18 months.(4)Test the systemWith the software and hardware acquired, you can now start testing the system in two stages: first unit testing and then system testing. If CASE tools have been used throughout the SDLC, testing is minimized because any automatically generated program code is more likely to be error free.5 Implement the System(1)What tasks are typically performed in the fifth phase of the SDLC?Whether the new information system involves a few handheld computers, and elaborate telecommunications network, or expensive mainframes, phase 5,systems implementation, with involve some close coordination to make the system not just workable but successful, and people are tainted to use it.6 Maintain the System(1)What two tools are often used in the maintenance phase of the SDLC?Phase 6, systems maintain, adjusts and improves the system by having system audits and periodic evaluations and by making changes based on new conditions.Even with the conversion accomplished and the users trained, the system won’t just run itself. There is a sixth-and never-ending –phase in which the information system must—monitored to ensure that it is effective. Maintenance includes not only keeping the machinery running but also updating and upgrading the system to keep pace with new products, services, customers, government regulations, and other requirements.附件二英汉翻译系统开发阶段随着社会的发展,个人关系管理在日常生活中起的左右显而易见,怎样增强个人管理管理能力,减少管理成本,加强服务水平和个人的竞争力是困扰每一个主管的重要问题之一。

计算机专业外文翻译

计算机专业外文翻译

PADE APPROXIMATION BY RATIONAL FUNCTION 129We can apply this formula to get the polynomial approximation directly for a given function f (x), without having to resort to the Lagrange or Newtonpolynomial. Given a function, the degree of the approximate polynomial, and the left/right boundary points of the interval, the above MATLAB routine ―cheby()‖ uses this formula to make the Chebyshev polynomial approximation.The following example illustrates that this formula gives the same approximate polynomial function as could be obtained by applying the Newton polynomial with the Chebyshev nodes.Example 3.1. Approximation by Chebyshev Polynomial. Consider the problem of finding the second-degree (N = 2) polynomial to approximate the function 2()1/(18)f x x =+. We make the following program ―do_cheby.m ‖, which uses the MATLAB routine ―cheby()‖ for this job and uses Lagrange/Newton polynomial with the Chebyshev nodes to do the same job. Readers can run this programto check if the results are the same.3.4 PADE APPROXIMATION BY RATIONAL FUNCTIONPade approximation tries to approximate a function f (x) around a point xo by a rational function00,00020012002012()()()()()()1()()()M M N N M M N N Q x x p x x D x x q q x x q x x q x x d x x d x x x x --=-+-+--+-+-+- ++=+d (3.4.1)where 00(2)0()0(),'(),(),,()M N f x f x f x f x + are known.How do we find such a rational function? We write the Taylor series expansion of f (x) up to degree M + N at x = xo as130 INTERPOLATION AND CURVE FITTING(2)0()00000020*******()()()()()'()()()()2()!()()()(3.4.2)M N M NM N M N M N f x f x f x T x x f x f x x x x x x x M N a a x x a x x a x x +++++≈-=+-+-++-+=+-+-++-Assuming 0x =0for simplicity, we get the coefficients of ()()N M D x andQ x such that()()0()M M N N Q x T x D x +-=011011()(1)()01M N N N M N N N N N a a x a x d x d x q q x q x d x d x++++++++-+++=+++ 01101()(1)()M N N N M N N N a a x a x d x d x q q x q x ++++++++=+++ (3.4.3) by solving the following equations:0010112110221122111212112212000M M M M N N M M M M M N N M M M M N N M N M N M N M N a q a a d q a a d a d q a a d a d a d q a a d a d a d a a d a d a d a a d a d a d ---+--+++-++++=⎧⎪+=⎪⎪+=⎪⎪⎪⎨⎪=⎪+=⎪⎪⎪⎪=⎩ ++++++++++++(3.4.4a )(3.4.4b ) Here, we must first solve Eq. (3.4.4b) for N d d d ,,,21 and then substitute di ‘s into Eq. (3.4.4a) to obtain M q q q ,,,10The MATLAB routine ―padeap()‖ implements this scheme to find the coefficient vectors of the numerator/denominator polynomial )(/)(x D x Q N M of thePade approximation for a given function f (x). Note the following things:ž The derivatives (2)()000'(),(),,()M N f x f x f x + up to order (M + N ) arecomputed numerically by using the routine ―difapx()‖, that will be introduced in Section 5.3.ž In order to compute the values of the Pade approximate function, we substitute 0x x - for x in ,()M N p x which has been obtained with the assumptionthat 0x =0.PADE APPROXIMATION BY RATIONAL FUNCTION 131Example 3.2. Pade Approximation for ()x f x e = . Let‘s find the Padeapproximation3,232()()/()p x Q x D x = for ()x f x e = around 0x =0. We make theMATLAB program ―do_pade.m ‖, which uses the routine ―padeap()‖ for this job and uses it again with no output argument to see the graphic results asdepicted in Fig. 3.6.To confirm and support this result from the analytical point of view and to help the readers understand the internal mechanism, we perform the hand-calculation 132INTERPOLATION AND CURVE FITTINGFigure 3.6 Pade approximation and Taylor series expansion for f(x) = ex (Example3.2.).procedure. First, we write the Taylor series expansion at x = 0 up to degree M + N = 5 for the given function ()x f x e = as()230()11()1!23!K M N k y k f x T x x x x x k +===++++∑ (E3.2.1)whose coefficients are0123111,1,,,26a a a a ==== (E3.2.2) We put this into Eq. (3.4.4b) with M = 3,N = 2 and solve it for di ‘s to get2212431223211211221()10,02/51/61/21/24,/201/241/61/120D x d x d x a a d a d a a d a d d d d d a =++++=++=--⎡⎤⎡⎤⎡⎤⎡⎤⎡⎤==⎢⎥⎢⎥⎢⎥⎢⎥⎢⎥-⎣⎦⎣⎦⎣⎦⎣⎦⎣⎦ (E3.2.3)Substituting this to Eq. (3.4.4a) yields001101221102332112111(2/5)3/51/21(2/5)1(1/20)3/201/6(1/2)(2/5)1(1/20)1/60q a q a a d q a a d a d q a a d a d ===+=+⨯-==++=+⨯-+⨯==++=+⨯-+⨯= (E3.2.4) INTERPOLATION BY CUBIC SPLINE 133 With these coefficients, we write the Pade approximate function as2333,222322()1(3/5)(3/20)(1/60)()()1(2/5)(1/20)(1/3)31220820Q x x x x p x D x x xx x x x x +++===+-++++-+ (E3.2.5)3.5 INTERPOLATION BY CUBIC SPLINEIf we use the Lagrange/Newton polynomial to interpolate a given set of N + 1 data points, the polynomial is usually of degree N and so has N − 1 local extrema (maxima/minima). Thus, it will show a wild swing/oscillation (called ‗polynomial wiggle‘), particularly near the ends of the whole interval as the number of data points increases and so the degree of the polynomial gets higher, as illustrated in Fig. 3.2. Then, how about a piecewise-linear approach, like assigning the individual approximate polynomial to every subinterval between data points? How about just a linear interpolation —that is, connecting the data points by a straight line? It is so simple, but too short of smoothness. Even with thesecond-degree polynomial, the piecewise-quadratic curve is not smooth enough to please our eyes, since the second-order derivatives of quadratic polynomials for ad jacent subintervals can‘t be made to conform with each other. In reallife, there are many cases where the continuity of second-order derivatives isdesirable. For example, it is very important to ensure the smoothness up to order 2 for interpolation needed in CAD (computer-aided design)/CAM (computer-aided manufacturing), computer graphic, and robot path/trajectory planning. That‘s why we often resort to the piecewise-cubic curve constructed by the individual thirddegree polynomials assigned to each subinterval, which is called the cubic splineinterpolation. (A spline is a kind of template that architects use to draw a smooth curve between two points.)For a given set of data points {(,),0:}k k x y k N =, the cubic spline s(x)consists of N cubic polynomial ()k s x ‘s assigned to each subinterval satisfying the following constraints (S0)–(S4).(S0)32,3,2,1,01()()()()(),[,],0:k k k k k k k k k k s x s x S x x S x x S x x S x x x k N +==-+-+-+∈=for (S1),0()0:k k k k s x S y k N ===,for(S2)1,0()(),1:1k k k k k k s x s x S y k N -≡===-for(S3)1,1'()'(),1:1k k k k k s x s x S k N -≡==-for(S4)1,2''()''()2,1:1k k k k k s x s x S k N -≡==-forThese constraints (S1)–(S4) amount to a set of N + 1 + 3(N − 1) = 4N − 2linear equations having 4N coefficients of the N cubic polynomials,0,1,2,3{,,,,0:1}k k k k S S S S k N =-134 INTERPOLATION AND CURVE FITTINGTable 3.4 Boundary Conditions for a Cubic Splineas their unknowns. Two additional equations necessary for the equations to besolvable are supposed to come from the boundary conditions for the first/secondorder derivatives at the end points (x 0, y 0) and (xN, yN ) as listed in Table 3.4.Now, noting from (S1) that ,0k k S y =, we will arrange the constraints (S2)–(S4)and eliminate Sk,1, Sk,3‘s to set up a set of equations with respect to the N + 1 unknowns ,2{,0:}k S k N =. In order to do so, we denote each interval width by 1k k k h x x +=- and substitute (S0) into (S4) to write1,3,2111,2,31,2,2''()62''()21()3k k k k k k k k k k k k s x S h S s x S S h S S +++++=+≡==- (3.5.1a)1,31,21,21()3k k k k S h S S ---=- (3.5.1b) We substitute these equations into (S2) with k + 1 in place of k321,31,21,11,0132,3,2,11()()()()k k k k k k k k k k k k k k k k k k k k k s x S x x S x x S x x S y S h S h S h y y ++++++=-+-+-+≡+++≡to eliminate ,3k S ‘s and rewrite it as11,2,2,2,1()3k k k k k k k k k kh y y S S S h S dy h ++--++== 1,2,2,1(2)33k k k k k h S S S dy +++= (3.5.2a ) 1,21,21,11(2)33k k k k k h S S S dy ----++= (3.5.2b ) We also substitute Eq. (3.5.1b) into (S3)211,311,211,1,1'()3k k k k k k k k s x S h S h S S ------=++≡INTERPOLATION BY CUBIC SPLINE 135to write,11,11,21,211,21,21,2()2()k k k k k k k k k k S S h S S h S h S S --------=-+=+ (3.5.3)In order to use this for eliminating Sk,1 from Eq. (3.5.2), we subtract (3.5.2b) from (3.5.2a) to write1,2,21,21,2,11,11(2)(2)3(2)3()k k k k k k k k k k h S S h S S S S dy dy +----+-++-=-and then substitute Eq. (3.5.3) into this to write1,2,21,21,21,21,2111,21,21,21(2)(2)3()3()()3()k k k k k k k k k k k k k k k k k k k k h S S h S S h S S dy dy h S h h S h S dy dy +--------+-+-+++=-+++=- (3.5.4)for k = 1 : N − 1 Since these are N − 1 equations with respect to N + 1 unknowns ,2{,0:}k S k N =, we need two more equations from the boundary conditions to be given aslisted in Table 3.4.How do we convert the boundary condition into equations? In the case where the first-order derivatives on the two boundary points are given as (i) in Table 3.4, we write Eq. (3.5.2a) for k = 0 as01,20,20,1000,201,200,1(2)33,233h S S S dy h S h S dy S ++=+=- (3.5.5a )We also write Eq. (3.5.2b) for k = N as1,21,21,11(2)33N N N N N h S S S dy ----++=and substitute (3.5.3)(k = N ) into this to write01,20,20,10(2)33h S S S dy ++=1,21,21,11,21,2111,21,2,11(2)33(2)323()N N N N N N N N N N N N N N h S S S h S S dy h S h S S dy ----------++-+=+=- (3.5.5b)Equations (3.5.5a) and (3.5.5b) are two additional equations that we need to solve Eq. (3.5.4) and that‘s it. In the case where the second -order derivatives on the two boundary points are given as (ii) in Table 3.4, 0,2S and ,2N S are directly known from the boundary conditions as0,200''()/2S s x =,,2''()/2N N N S s x = (3.5.6) 136 INTERPOLATION AND CURVE FITTINGand, subsequently, we have just N − 1 unknowns. In the case where the secondorderderivatives on the two boundary points are given as (iii) in Table 3.4we can instantly convert these into two equations with respect to S 0,2 and SN,2 as Finally, we combine the two equations (3.5.5a) and (3.5.5b) with Eq. (3.5.4) to write it in the matrix –vector form as0,200,1001,21000111,2122211,2,11113()203()2()003()2()3()02N N N N N N N N N N N N S dy S h h S dy dy h h h h S dy dy h h h h S S dy h h -----------⎡⎤⎡⎤⎡⎤⎢⎥⎢⎥⎢⎥-+⎢⎥⎢⎥⎢⎥⎢⎥⎢⎥⎢⎥=⎢⎥⎢⎥⎢⎥-+⎢⎥⎢⎥⎢⎥⎢⎥⎢⎥⎢⎥-⎣⎦⎣⎦⎣⎦(3.5.8) After solving this system of equation for {Sk,2, k = 0 : N }, we substitute theminto (S1), (3.5.2), and (3.5.1) to get the other coefficients of the cubic spline asThe MATLAB routine ―cspline()‖ constructs Eq.(3.5.8), solves it to get the cubic spline coefficients for given x, y coordinates of the data points and the boundary conditions, uses the mkpp() routine to get the piecewise polynomialexpression, and then uses the ppval() routine to obtain the value(s) of the piecewise polynomial function for xi —that is, the interpolation over xi. The type ofthe boundary condition is supposed to be specified by the third input argument KC. In the case where the boundary condition is given as (i)/(ii) in Table 3.4,the input argument KC should be set to 1/2 and the fourth and fifth input arguments must be the first/second derivatives at the end points. In the case wherethe boundary condition is given as extrapolated like (iii) in Table 3.4, the input argument KC should be set to 3 and the fourth and fifth input arguments do not need to be fed.INTERPOLATION BY CUBIC SPLINE 137(cf) See Problem 1.11 for the usages of the MATLAB routines mkpp() and ppval(). Example 3.3. Cubic Spline. Consider the problem of finding the cubic spline interpolation for the N + 1 = 4 data pointssubject to the boundary condition(E3.3.2)With the subinterval widths on the x-axis and the first divided differences as138INTERPOLATION AND CURVE FITTINGwe write Eq. (3.5.8) as0,200,11,2102,2213,23,113()210033()141063()014163()00123S dy S S dy dy S dy dy S S dy --⎡⎤⎡⎤⎡⎤⎡⎤⎢⎥⎢⎥⎢⎥⎢⎥-⎢⎥⎢⎥⎢⎥⎢⎥==⎢⎥⎢⎥-⎢⎥⎢⎥-⎢⎥⎢⎥⎢⎥⎢⎥-⎣⎦⎣⎦⎣⎦⎣⎦ (E3.3.4)Then we solve this equation to get and substitute this into Eq. (3.5.9) to obtain0,01,02,000,102,20,211,112,21,222,123,21,21,20,20,301,21,21,313,22,30,1,4( 3.3.6)(2)2( 3.3.7)3(2)2( 3.3.7)3(2)2( 3.3.7)32( 3.3.8)32( 3.3.8)3S S S E h S dy S S E a h S dy S S E b h S dy S S E c S S S E a h S S S E b h S S ====-+==-+==-+=-==-==--=2,222( 3.3.8)3S E c h =Figure 3.7 Cubic splines for Example 3.3.Finally, we can write the cubic spline equations collectively from (S0) asWe make and run the program ―do_csplines.m‖, which uses the routine―cspline()‖ to compute the cubic spline coefficientsand obtain the value(s) of the cubicspline function for i x(i.e., theinterpolation over xi) and then plots the result as depicted in Fig. 3.7. We also compare this result with that obtained by using the MATLAB built-in function―spline(x,y,xi)‖, which works with the boundary condition of type (i) for the second input argument given as [dy0 y dyN], and with the boundary conditionof type (iii) for the same lengths of x and y.3.6 HERMITE INTERPOLATING POLYNOMIALIn some cases, we need to find the polynomial function that not only passes through the given points, but also has the specified derivatives at every data point. We call such a polynomial the Hermite interpolating polynomial or the osculating polynomial.140 INTERPOLATION AND CURVE FITTINGFor simplicity, we consider a third-order polynomialmatching just two points and having the specified first derivativesat the points. We can obtain the four coefficients by solvingAs an alternative, we approximate the specified derivatives at the data points by their differencesand find the Lagrange/Newton polynomial matching the four pointsThe MATLAB routine ―hermit()‖ constructs Eq. (3.6.2) and solves it to getthe Hermite interpolating polynomial coefficients for a single interval given the two end points and the derivatives at them as the input arguments. The next routine ―hermits()‖ uses ―hermit()‖ to get the Hermite coefficients for a setof multiple subintervals.Example 3.4. Hermite Interpolating Polynomial. Consider the problem of finding the polynomial interpolation for the N + 1 = 4 data pointsTWO-DI MENSIONAL INTERPOLATION 141subject to the conditionsFor this problem, we only have to type the following statements in the MATLAB command window.3.7 TWO-DIMENSIONAL INTERPOLATIONIn this section we deal with only the simplest way of two-dimensional interpolation—that is, a generalization of piecewise linear interpolation calledFigure 3.8 A two-dimensional interpolation using Zi = interp2() on the grid points [Xi,Yi] generated by the meshgrid() command.142 INTERPOLATION AND CURVE FITTINGthe bilinear interpolation. The bilinear interpolation for a point (x, y ) on the rectangularsub-region having and as its left-upper/right-lower corner points is described by the following formula.11111,1111,11,11,11(,)(,)(,)1{()()()()()()()()()()},,n n n n n n n n m n m n m m n n m n m n m n m n m n m n m m n ny y y y z x y z x y z x y y y y y x x y y z x x y y x x y y z x x y y z x x y y z x x x y y y -----------------=+--=----+--+--+--≤≤≤≤for (3.7.2)This formula is cast into the MATLAB routine ―intrp2()‖, which is so named in order to distinguish it from the MATLAB built-in routine ―interp2()‖. Note that in reference to Fig. 3.8, the given values of data at grid points (x(m),y(n)) and the interpolated values for intermediate points (xi(m),yi(n)) are stored in Z(n,m) and Zi(n,m), respectively.CURVE FITTING 143Example 3.5. Two-Dimensional Bilinear Interpolation. We consider interpolating the sample values of a functionfor the 5 × 5 grid over the 21 × 21 grid on the domainWe make the MATLA B program ―do_interp2.m‖, which uses the routine―intrp2()‖ to do this job, compares its function with that of the MATLABbuilt-in routine ―interp2()‖, and computes a kind of relative error to estimatehow close the interpolated values are to the original values. The graphic resultsof running this program are depicted in Fig. 3.9, which shows that we obtaineda reasonable approximation with the error of 2.6% from less than 1/16 of the original data. It is implied that the sampling may be a simple data compression method, as long as the interpolated data are little impaired.3.8 CURVE FITTINGWhen many sample data pairs {(xk, yk), k = 0 : M} are available, we often need to grasp the relationship between the two variables or to describe the trend of the(a) True function (b) The function over (c) Bilinear interpolation Figure 3.9 Two-dimensional interpolation (Example 3.5).144 INTERPOLATION AND CURVE FITTINGsample grid data, hopefully in a form of function y = f (x). But, as mentioned in Remark 3.1,the polynomial approach meets with the polynomial wiggle and/or Runge phenomenon,which makes it not attractive for approximation purpose. Although thecubic spline approach may be a roundabout toward the smoothness as explainedin Section 3.5, it has too many parameters and so does not seem to be an efficient way of describing the relationship or the trend, since every subintervalneeds four coefficients. What other choices do we have? Noting that many dataare susceptible to some error, we don‘t ha ve to try to find a function passing exactly through every point. Instead of pursuing the exact matching at every data point, we look for an approximate function (not necessarily a polynomial) that describes the data points as a whole with the smallest error in some sense, whichis called the curve fitting.As a reasonable means, we consider the least-squares (LS) approach to minimizing the sum of squared errors, where the error is described by the verticaldistance to the curve from the data points. We will look over various types of fitting functions in this section.3.8.1 Straight Line Fit: A Polynomial Function of First DegreeIf there is some theoretical basis on which we believe the relationship betweenthe two variables to bewe should set up the following system of equations from the collection of many experimental data:Noting that this apparently corresponds to the overdetermined case mentionedin Section 2.1.3, we resort to the least-squares (LS) solution (2.1.10)which minimizes the objective functionCURVE FITTING 145Sometimes we have the information about the error bounds of the data, and it is reasonable to differentiate the data by weighing more/less each one according toits accuracy/reliability. This policy can be implemented by the weighted leastsquares (WLS) solutionwhich minimizes the weighted objective functionIf the weighting matrix is, then we can write the WLS solution (3.8.5) aswhereOne may use the MATLAB built-in routine ―lscov(A,y,V)‖ to obtain thisWLS solution.3.8.2 Polynomial Curve Fit: A Polynomial Function of Higher DegreeIf there is no reason to limit the degree of fitting polynomial to one, then we may increase the degree of fitting polynomial to, say, N in expectation of decreasing the error. Still, we can use Eq. (3.8.4) or (3.8.6), but with different definitions of A and θ asThe MATLAB routine ―polyfits()‖ performs the WLS or LS scheme tofind the coefficients of a polynomial fitting a given set of data points, depending on whether or not a vector (r) having the diagonal elements of the weighting matrix W is given as the fourth or fifth input argument. Note that in the case of a diagonal weighting matrix W, the WLS solution conforms to the LS solution with each row of the information matrix A and the data vector y multiplied by the corresponding element of the weighting matrix W. Let us see the following examples for its usage:146 INTERPOLATION AND CURVE FITTINGExample 3.6. Polynomial Curve Fit by LS (Least Squares). Suppose we havein two columns and we must fit these data into polynomials of degree 1, 3, 5, and 7.We make the MATLAB program ―do_polyfit.m‖, which uses the routine―polyfits()‖ to do this job and plot the results together with the given dataCURVE FITTING 147Figure 3.10 Polynomial curve fitting by the LS (Least-Squares) method.points as depicted in Fig. 3.10. We can observe the polynomial wiggle that the oscillation of the fitting curve between the data points becomes more pronounced with higher degree.Example 3.7. Curve Fitting by WLS (Weighted Least Squares). Most experimental data have some absolute and/or relative error bounds that are not uniform forall data. If we know the error bounds for each data, we may give each data a weight inversely proportional to the size of its error bound when extracting valuable information from the data. The WLS solution (3.8.7) enables us to reflect sucha weighting strategy on estimating data trends. Consider the following two cases. (a) Suppose there are two gauges A and B with the same function, but different absolute error bounds ±0.2 and ±1.0, respectively. We used themto get the input-output data pair (xm,ym) as{(1, 0.0831), (3, 0.9290), (5, 2.4932), (7, 4.9292), (9, 7.9605)} from gauge A {(2, 0.9536), (4, 2.4836), (6, 3.4173), (8, 6.3903), (10, 10.2443)} from gauge B Let the fitting function be a second-degree polynomial function148 INTERPOLATION AND CURVE FITTING(a) Fitting to a polynomial (b) Fitting toFigure 3.11 LS curve fitting and WLS curve fitting for Example 3.7.To find the parameters a2, a1, and a0, we write the MATLAB program―do_wlse1.m‖, which uses the routine ―polyfits()‖ twice, once without weighting coefficients and once with weighting coefficients. The resultsare depicted in Fig. 3.11a, which shows that the WLS curve fitting triesto be closer to the data points with smaller error bound, while the LScurve fitting weights all data points equally, which may result in larger deviations from data points with small error bounds.(b) Suppose we use one gauge that has relative error bound ±40[%] for measuring the output y for the input values x = [1, 3, 5, . . . , 19] and sothe size of error bound of each output data is proportional to the magnitudeof the output. We used it to get the input–output data pair (xm,ym) as{(1, 4.7334), (3, 2.1873), (5, 3.0067), (7, 1.4273), (9, 1.7787)(11, 1.2301), (13, 1.6052), (15, 1.5353), (17, 1.3985), (19, 2.0211)}Let the fitting function be an exponential functiony = axb (E3.7.2)To find the parameters a and b, we make the MATLAB program―do_wlse2.m‖, which uses the routine ―curve_fit()‖ without the weighting coefficients one time and with the weighting coefficients another time.The results depicted in Fig. 3.11b shows that the WLS curve fitting tries toget closer to the data points with smaller |y|, while the LS curve fitting pays equal respect to all data points, which may result in larger deviation fromdata points with small |y|. Note that the MATLAB routine ―curve_fit()‖appears in Problem 3.11, which implements all of the schemes listed inTable 3.5 with the LS/WLS solution.CURVE FITTING 149(cf) Note that the objective of the WLS scheme is to put greater emphasis on more reliable data.插值与拟合我们能够运用这个公式直接得到给定函数f(x)的近似多项式估计,没有必要采取拉格朗日或牛顿多项式。

计算机专业外文翻译---Visual Basic 语言与算法

计算机专业外文翻译---Visual Basic 语言与算法

Visual Basic language and arithmeticThe United States launched the Microsoft Visual Basic (may be referred to VB), is the latest version of the current VB 2008 Beta2 (VB9) Chinese version.Visual meaning the visual, visible, referring to the development of operating systems like windows graphical user interface (Graphic User Interface, GUI) method, it does not need to prepare a large number code to describe the appearance of the interface elements and location, as long as the pre - The establishment of good drag and drop objects on the screen corresponding to the location.Basic is actually an abbreviation of the phrase; this phrase is Beginners all-purpose symbolic instruction code, the Chinese meaning "to the initial directive GM symbol code language."Visual Basic learning, Professional Edition and Enterprise Edition versions to meet the different needs of the development. Study and apply to the ordinary version of the majority of learners and the use of Visual Basic development of the general staff of Windows applications, but; professional version for computer professional development of staff, including the study of functional version of the full content control and Internet development tools such as advanced features ,Enterprise contain not only all the professional version of the content, there are automated tools such as Component Manager, professional programmers to make the development of a powerful group essence of distributed applications.Visual BasicSection 1 the summary of Visual BasicMicrosoft Visual Basic,( abbreviate VB )as tool the most of application program one of under Windows operating platform. No matter beginner or professional developer, VB has all offered a whole set of tools to them, Development application program that it can be relaxed and convenient. So VB as most computer first-selected the ABC of programming language of beginner." Visual" mean method to adopt visual user of development figure interface (GUI), need and write a large number of code go and describe interface appearance and position of element seldom, Tow and show controlling part that need corresponding position to get screen can help figure design interface, user of figure,; " Basic" means BASIC language, because VB is developed on the basis of already existing BAISC language.VB is a kind of programming language in common use of Microsoft, It, including VBA of the numerous Windows application software use VB language in Microsoft Excel, Microsoft Accessed., For users to carry on the secondary development; Make web page use more VBScript script language sub collection of VB too at present.Utilize data of VB visit characteristic user can establish the data base to most data base forms including Microsoft SQL Server and other enterprises data base With the application program of front, and adjustable service end part. Utilize ActiveX(TM) technology, VB can use word processor, electronic data list he Windows function that application program offers extremely, Excel of Microsoft,, Word of Microsoft,, Even can use by VB specialty edition or enterprise application program and target thatedition establish directly.The procedure that users established finally is a real .EXE file , can issue freely .VB offer study edition, the specialty edition and enterprise edition, use to satisfied with different development demands. Study edition make programming personnel develop Windows and Windows application program of NT very easily. The specialty edition has offered the developing instrument with complete function to programming personnel of the specialty, Include studying all functions of edition in the specialty edition. Enterprise edition allow the professional personnel to establish strong distributed application program in the form of group. It includes all characteristics of the specialty edition. So can choose different editions according to different needs.Section 2 integrated development environmentsIntegrated environment of VB call IDE, made up of a lot of parts , include title board, menu fence, tool fence, controlling part case, And window body window, engineering management device window, attribute window, code window and window body overall arrangement window body overall arrangement, etc. of designing etc.. Have covered all functions, such as design which develops the application program, editting, compiling and debugging, etc..In VB, the application program calls the project too. When start VB and open a new project for the first time, can see and pursue integrated development environment interface that show.Visual Basic Integrated development environmentVB come and organize development of application program through project, use project come and manage and form files of application program. One project uses the environment to make up by several window bodies, standard module generally. The system manages project through the project menu, for instance add the window body, quote . System allow turn on and manage a lot of projects besides.Section 3 Visual Basic language brief introductionsBasic use and do the elementary high-level language that used often most. Its full name is Beginner' s All-purpose Symbolic Instruction Code, abbreviate as BASIC. As its name suggests, Basic one specially for language that beginner design, because it easy to learn easy to know, So the body is popular. Early Basic language to belong to and solve translating type, so can carry out line by line , So it can see the result carried out at once , this is a very convenient design for beginner. But it have concept of structure either, one that is in procedure maintain and management have as much as other language problems. But back-end Basic correct shortcoming of the above (such as Quick Basic), make it may used for and develop the large-scaler procedure too.The language is the basic composition, which forms VB procedure. VB has stipulated the form of sentences and function.Grammar:The sentence defines incantations [Sentence body]Sentence define agree with and used in fixed function of sentence, sentence body appoint concrete content or want concrete operation that carry out of sentence. All set of sentence VB language, carry on with VB sentence organic association finish acertain specific function the procedure. Interface + procedure can solve a certain application problem.VB application program code window write in" code editing machine" generally. " editing machine of code" is like the word processing software of a piece of height specialization, there are many easies function of writing VB code, Pursue to show [Example Ex-Hello ]In" code editing machine" code that window written.“Editing machine of code” windowSection 4 develop the application program with Visual BasicUse VB programming, design appearance of application program first generally, write every target procedure code or other treatment procedure of incident respectively, Work of programming should be light more.The procedure of establishing the application program is as follows:Establish application program interfaceThe interface is the mutual bridge of user and procedure, Generally formed of window body and vision frame of the button, menu, text frameset. with standard WINDOWS interface of application program that VB establish. Require according to function of procedure and user and need of information interchange of procedure, Come to confirm that need those targets , plan the overall arrangement of the interface.2. Design by each attributes of target in interfaceDemand and set up each attribute of target such as appearance, name,, size of targeted. according to interface of planning.Most attribute person who fetch can set up through the attribute window when design already, Too can set up revising when operating in procedure through programming in procedure code. Have the targets respond programming by procedure code3. Respond procedure code of programming targetInterface determine appearance of procedure only, design window add codes through" code editing machine" soon after the interface, Realize some make the tasks, such as responding, information processing,etc. after accepting external message, Add code , realize some response, information processing that make after accepting external information task, As editor's window of code pursued shows add codes “code editing machine” wi ndow4. Keep projectOne VB procedure one project, at the time of designing a application program, system will set up one be expanded and called. Project file of vbp, project file include all relevant information of file that project set up this, Keep project keep associated documents of project this at the same time. For example the window body produced when design interfaces is kept and being expanded and being called. Frm sum. In the window body of foxfire. At the time of opening a project( file), this project relevant files load at the same time.5. Operate and debugged by procedureOperate the procedure thoroughpin operate" selecting in the menu, when the mistake appears, VB system can offer information prompt can looked for and get ridof the mistake thoroughpin debug" within operate" menus too.6. Can produce by executive programFor make procedure can break away from VB environment, order to become next life through" file"" producing project 1.exe" of menu but executive program (eyeful), Can carry out this file directly after this. In produce, + executive program, and then through install guide bale all associated documents, Can run independently after installation under the environment of windows 9 x/2000 as a software product.In computer system's any software, is by the every large or small each kind of software constituent constitution, defers to the specific algorithm to realize respectively, the algorithm quality direct decision realizes the software performance fit and unfit quality. Designs the algorithm with any method, what resources designs the algorithm to need, requires how many running time, how many storage space, how to determine an algorithm the quality, when realizes a software, is must give to solve. In computer system's operating system, the language compiling system, the database management system as well as in various computer application system's software, must use each one concrete algorithm to realize. Therefore, the algorithm design and the analysis are the computer science and a technical core question.The algorithm is the problem-solving step, we may define the algorithm Cheng Jie a determination class question the random one special method. In the computer science, the algorithm needs to use the computer algorithmic language to describe, the algorithm represents with the computer solves a kind of question precisely, the effective method. The algorithm construction of data = procedure, solves one to assign may calculate or the solvable question, the different person may compile the different procedure, solves the identical problem, here has two problems: First, with computational method close related algorithm question; Second, programming technical question. Between the algorithm and the procedure has the close relationship. The algorithm is a group has the poor rule, they had stipulated solves some specific type question a series of operations, is to the problem solving plan accurate and the complete description. Formulates an algorithm, generally must pass through stages and so on design, confirmation, analysis, code, test, debugging, time. To algorithm study including five aspect contents:① Design algorithm. The algorithm design work is impossible completely the automation, should study the understanding already by the practice to prove that was the useful some basic algorithm design method, these basic design method was not only suitable for the computer science, moreover was suitable for domains and so on electrical engineering, operations research;②Expresses the algorithm. The description algorithm's method has many kinds of forms, for example the natural language and the algorithmic language, have the suitable environment and the characteristic respectively;③Confirms the algorithm. The algorithm confirmed the goal is causes the people to believe firmly that this algorithm can work unmistakably correctly, namely this algorithm has the circularity. The correct algorithm describes with the computer algorithmic language, constitutes the computer program, the computer program moves on the computer, obtains thealgorithm operation result;④ Parsing algorithm. The algorithmic analysis is requires how many computing time and the storage space to an algorithm makes the quota the analysis. The parsing algorithm may forecast that what environment this algorithm does suit in moves effectively, to solves the identical question different algorithm validity to make the comparison;⑤ Confirmation algorithm. With machine language description algorithm whether can calculate effectively, reasonable, must carry on the test to the procedure, the test order work and makes the space and time distribution map by the debugging to be composed.But the algorithm has certain characteristic, it includes:①Determinism. Algorithm each kind of operation must have the determination significance, this kind of operation should carry out what kind of movement should not to have the ambiguity, the goal is clear;②Effectiveness. Requests the operation which in the algorithm waits for realizing is basic, each kind of operation can at least completes in the principle by the human with the paper and the pen in the limited time;③ Input. An algorithm has 0 or the many inputs, before the algorithm operation starts gives the algorithm to need the data the starting value, these inputs are from the specific object set;④Output. Does for the algorithm operation result, an algorithm has or many outputs, the output has some kind of specific relational quantity with the input;⑤ Has poor. An algorithm always after carrying out had the poor step operation has terminated, namely this algorithm was may reach.Satisfies a first four characteristic group of rule not to be able to be called the algorithm, can only be called the computational process, the operating system is a computational process example, the operating system uses for to manage the computer resources, controls the manufacture industry movement, when has not made industry the movement, the computational process does not stop, but is at the waiting status.The algorithm complexity is the algorithm efficiency measure, when appraises the algorithm performance, the complexity is an important basis. The algorithm complex degree with moves computer resources how many which this algorithm needs related, needs the resources are more, indicated that this algorithm the complexity is higher; Needs the resources are less, indicated that this algorithm the complexity is lower.The spatial resources, which computer’s resources, operate most importantly, needs the time which and the stored routine and the data need, the algorithm complexity has division time complexity and the spatial complexity.The algorithm carries out the operation on the computer, needs the data which certain storage space depositing description algorithm the procedure and the algorithm need, the computer completes the operation task to require certain time. The procedure which writes according to the different algorithm places when on the computer operates, needs the time and the space are different, the algorithm complexity is needs the time and the spatial one kind of measure to the algorithm operation. The different computer its operating speed difference is very big, is weighing an algorithm the complexity to note this point.Regarding question, which assigns willfully, a profitable target which designs,the complex low algorithm is as far as possible when designs algorithm considered. Moreover, when the question, which assigns already when has many kinds of algorithms, an important criterion which choice complexity low, is when selects algorithm should follow. Therefore, the algorithm complex analysis or selects to the algorithm design has the important guiding sense and the use value.When discussion algorithm complexity, two questions need to clarify:(1) An algorithm's complexity expresses with what kind of quantity;(2) How to calculate one to assign the algorithm the complexity. After finding solves a question the algorithm, is this algorithm realization, as for whether could find the method which realized, was decided in the algorithm circularity and the computation complexity, whether this question did have the solution algorithm, whether to provide the time resources which and the spatial resources the algorithm needed.Visual Basic 语言与算法1991年,美国微软公司推出了Visual Basic(可简称VB),目前的最新版本是VB 2008 Beta2(VB9)中文版。

计算机系统外文翻译

计算机系统外文翻译

外文文献翻译院系机电与自动化学院专业班级电气0801 姓名原文出处 IEEE的论文评分指导教师20 12 年 2 月 18 日大多数计算机系统嵌入在今天使用其他设备,包括电话、钟表、电器、车辆和基础设施。

嵌入式系统通常很少有要求长度和记忆和程序可能需要简单但不寻常的输入/输出系统。

例如,大多数嵌入式系统中缺乏键盘,屏幕磁盘,打印机,或其他可辨认的I / O设备一台个人电脑。

他们可能控制电机、继电器或母线电压、读到的开关、可变电阻或其他电子设备与通用CPU、微控制器没有地址总线或数据总线,因为他们整合与非挥发性内存为主的公绵羊在同一芯片CPU。

因为他们需要更少的针、芯片可以放置在一个更小的、廉价的包裹记忆和其他外围设备集成在一个芯片上,作为一个单元测试的成本的增加的芯片,但是经常导致净成本降低了嵌入式系统作为一个整体。

(即使CPU,它的成本还集成外设略多于成本是一个CPU +外部外设,几乎没有芯片通常允许一个小、更便宜,降低电路板的劳动要求的电路板组装和测试)。

单片机是一个单一集成电路,通常与以下特点:中央处理器——从小、简单到复杂的32 - 4比特处理器或64位处理器输入/输出接口,如串行端口(UARTs)其他系列通信接口就像我²C、串行外设接口和控制器局域网系统互连外设(如定时器和监督来存储数据存储器,可擦可编程只读存储器,EEPROM或者闪存程序存储器——通常一个时钟生成器的石英晶体振荡器的时机,谐振器或RC电路包括类比数位转换器许多。

这种整合的数量大幅度降低芯片和数量的接线、PCB空间生产需要用分开的等价系统芯片和证明了是在嵌入式系统中非常流行,因为他们的介绍在1970年代。

单片机结构可以从许多不同的供应商在那么多品种,每个指令集建筑可以理所当然地应属于他们自己的一个范畴。

最首要的是8051,Z80和手臂的衍生物。

[引用需要]单片机(MCU或者µC)是计算机system-on-a-chip功能。

从古至今的计算方法

从古至今的计算方法

从古至今的计算方法英文回答:Early History of Computation.The earliest forms of computation date back to ancient times, when people used simple tools to perform basic calculations. The abacus, a device consisting of beads strung on rods, was invented by the Babylonians around 2700 BCE. It was used for arithmetic calculations, including addition, subtraction, multiplication, and division.Around the same time, the Egyptians developed the hieroglyphic numeral system, which used symbols to represent numbers. This system was later adopted by the Greeks and Romans, who used it for mathematical calculations.Medieval Era.During the Middle Ages, Arab mathematicians made significant contributions to the development of computation. They introduced the concept of zero and developed new algorithms for solving mathematical problems. The astrolabe, an instrument used for astronomical calculations, was also invented during this time.In Europe, the abacus remained the primary tool for computation until the 13th century, when the Hindu-Arabic numeral system was introduced. This system, which is still used today, made it easier to perform complex calculations.Renaissance and Enlightenment.The Renaissance and Enlightenment periods saw further advancements in computation. The invention of the printing press in the 15th century made it possible to mass-produce mathematical tables and other aids for computation.During the 17th century, scientists such as René Descartes and Pierre de Fermat developed analytic geometry, which provided a new way to solve geometric problems. Thisled to the development of calculus, which is essential for advanced mathematics and science.19th Century and Beyond.The 19th century witnessed the development of mechanical calculators, such as the difference engine and the analytical engine, which were designed by Charles Babbage. These devices could perform complex calculations automatically.In the early 20th century, the invention of the electronic computer revolutionized computation. Electronic computers are much faster and more powerful than mechanical calculators, and they can be used for a wide range of tasks, from scientific research to business applications.Modern Era.The development of personal computers in the 1970s and 1980s made it possible for individuals to have access to powerful computing capabilities in their homes and offices.The internet, which was developed in the 1990s, has made it possible to share data and collaborate on projects from anywhere in the world.Today, computation is an essential part of modern society. It is used in everything from financial transactions to scientific research to entertainment. The development of computation has made it possible to solve complex problems and achieve new heights of human achievement.中文回答:计算方法的演变。

计算机外文翻译---J2ME和JAVA领域

计算机外文翻译---J2ME和JAVA领域

毕业设计(论文)外文资料翻译系:计算机系专业:计算机科学与技术姓名:学号:外文出处:JAVA 2 Micro Edition and the World(用外文写)of JAVA[EB/OL].[2012-02-28].http:///view/7e71db9c51e79b8968022609.html附件: 1.外文资料翻译译文;2.外文原文。

附件1:外文资料翻译译文J2ME和JAVA领域1.介绍20世纪70年代以来随着计算机革命的开始,对计算机先进软件的需求大大增加,从而可以充分利用功能日益增强的精密的计算机的处理数据的能力。

C编程语言逐渐成为支柱,使程序员开发软件像计算机运行一样流畅。

80年代以来,程序员又目睹了编程语言领域的又一次变革的高潮。

C语言的编程能力已经不能满足计算机的技术发展的需要。

这问题并不是新问题。

它造成了一代又一代的编程语言的新老更替。

问题是,它使得程序设计过于复杂,从而使计算机软件的设计,编写和开发落后于硬件的发展。

就是这个时候,两种基于设计概念的编程语言Simula 67和Smalltalk(从上世纪60年代末)带来了接近编程语言未来前景的循序渐进的步骤。

这期间,当面向对象编程(OOP),与它一种新的编程语言,所谓的C++在程序员中掀起了一场风暴。

1979年,Bjarne Stroustrup的在新泽西州的贝尔实验室增强了C 语言,使其具有面向对象的特点即所谓的C++语言 (++是C编程语言增强的承载符号)。

C++是一个真正的提高的C编程语言,它开始是一种前置语言,该计划最初是一种编译工具。

St roustrup建立类的概念(借用了Simula 67和Smalltalk中的概念),由类则可以创建实例对象。

一个类包含数据成员和定义对象数据和功能的成员函数。

他还介绍了继承的概念,使一类继承其他一个或多个类的部分或全部数据成员或成员函数,职能由一个或多个其他类别-所有这些概念就是面向对象的编程。

计算机外文翻译---计算机引论

计算机外文翻译---计算机引论

计算机外文翻译---计算机引论计算机外文翻译计算机引论在当今数字化的时代,计算机已经成为了我们生活中不可或缺的一部分。

从日常的通信交流到复杂的科学研究,从娱乐休闲到工业生产,计算机的身影无处不在。

那么,究竟什么是计算机?它又是如何发展演变而来的呢?计算机,简单来说,是一种能够按照预先设定的程序,对数据进行存储、处理和输出的电子设备。

它的核心功能包括数据处理、信息存储和通信等。

计算机的发展可以追溯到古代。

早期人类使用算筹、算盘等工具进行简单的计算。

然而,这些工具的功能非常有限,只能处理一些基本的数学运算。

直到 19 世纪,查尔斯·巴贝奇提出了差分机和分析机的概念,这被认为是现代计算机的先驱。

虽然巴贝奇的设计在当时由于技术限制未能完全实现,但他的思想为后来计算机的发展奠定了基础。

进入 20 世纪,电子技术的飞速发展为计算机的诞生创造了条件。

1946 年,世界上第一台通用电子计算机 ENIAC 问世。

ENIAC 体积庞大,使用了大量的电子管,但它的出现标志着计算机时代的正式开启。

随着技术的不断进步,计算机经历了多次变革。

从使用电子管到晶体管,再到集成电路和大规模集成电路,计算机的体积越来越小,性能却越来越强大。

如今,计算机已经发展出了多种类型,包括个人计算机(PC)、服务器、超级计算机等。

个人计算机通常用于日常办公、学习和娱乐;服务器则为企业和互联网提供数据存储和处理服务;超级计算机则用于进行大规模的科学计算和模拟,如天气预报、药物研发等。

计算机的硬件是其运行的基础。

硬件主要包括中央处理器(CPU)、内存、硬盘、显卡、主板等组件。

CPU 是计算机的“大脑”,负责执行计算和控制任务;内存用于暂时存储正在运行的程序和数据;硬盘则用于长期存储各种信息;显卡负责处理图像和视频相关的任务;主板则将各个组件连接在一起,实现它们之间的通信。

软件则是计算机的“灵魂”。

软件包括系统软件和应用软件。

系统软件如操作系统,负责管理计算机的硬件资源和提供基本的服务;应用软件则是为了满足用户的特定需求而开发的,如办公软件、游戏、图形设计软件等。

计算机专业外文文献翻译

计算机专业外文文献翻译

毕业设计(论文)外文文献翻译(本科学生用)题目:Plc based control system for the music fountain 学生姓名:_ ___学号:060108011117 学部(系): 信息学部专业年级: _06自动化(1)班_指导教师: ___职称或学位:助教__20 年月日外文文献翻译(译成中文1000字左右):【主要阅读文献不少于5篇,译文后附注文献信息,包括:作者、书名(或论文题目)、出版社(或刊物名称)、出版时间(或刊号)、页码。

提供所译外文资料附件(印刷类含封面、封底、目录、翻译部分的复印件等,网站类的请附网址及原文】英文节选原文:Central Processing Unit (CPU) is the brain of a PLC controller. CPU itself is usually one of the microcontrollers. Aforetime these were 8-bit microcontrollers such as 8051, and now these are 16-and 32-bit microcontrollers. Unspoken rule is that you’ll find mostly Hitachi and Fujicu microcontrollers in PLC controllers by Japanese makers, Siemens in European controllers, and Motorola microcontrollers in American ones. CPU also takes care of communication, interconnectedness among other parts of PLC controllers, program execution, memory operation, overseeing input and setting up of an output. PLC controllers have complex routines for memory checkup in order to ensure that PLC memory was not damaged (memory checkup is done for safety reasons).Generally speaking, CPU unit makes a great number of check-ups of the PLC controller itself so eventual errors would be discovered early. You can simply look at any PLC controller and see that there are several indicators in the form. of light diodes for error signalization.System memory (today mostly implemented in FLASH technology) is used by a PLC for a process control system. Aside form. this operating system it also contains a user program translated forma ladder diagram to a binary form. FLASH memory contents can be changed only in case where user program is being changed. PLC controllers were used earlier instead of PLASH memory and have had EPROM memory instead of FLASH memory which had to be erased with UV lamp and programmed on programmers. With the use of FLASH technology this process was greatly shortened. Reprogramming a program memory is done through a serial cable in a program for application development.User memory is divided into blocks having special functions. Some parts of a memory are used for storing input and output status. The real status of an input is stored either as “1”or as “0”in a specific memory bit/ each input or output has one corresponding bit in memory. Other parts of memory are used to store variable contents for variables used in used program. For example, time value, or counter value would be stored in this part of the memory.PLC controller can be reprogrammed through a computer (usual way), but also through manual programmers (consoles). This practically means that each PLC controller can programmed through a computer if you have the software needed for programming. Today’s transmission computers are ideal for reprogramming a PLC controller in factory itself. This is of great importance to industry. Once the system is corrected, it is also important to read the right program into a PLC again. It is also good to check from time to time whether program in a PLC has not changed. This helps to avoid hazardous situations in factory rooms (some automakers have established communication networks which regularly check programs in PLC controllers to ensure execution only of good programs). Almost every program for programming a PLC controller possesses various useful options such as: forced switching on and off of the system input/outputs (I/O lines),program follow up in real time as well as documenting a diagram. This documenting is necessary to understand and define failures and malfunctions. Programmer can add remarks, names of input or output devices, and comments that can be useful when finding errors, or with system maintenance. Adding comments and remarks enables any technician (and not just a person who developed the system) to understand a ladder diagram right away. Comments and remarks can even quote precisely part numbers if replacements would be needed. This would speed up a repair of any problems that come up due to bad parts. The old way was such that a person who developed a system had protection on the program, so nobody aside from this person could understand how it was done. Correctly documented ladder diagram allows any technician to understand thoroughly how system functions.Electrical supply is used in bringing electrical energy to central processing unit. Most PLC controllers work either at 24 VDC or 220 VAC. On some PLC controllers you’ll find electrical supply as a separate module. Those are usually bigger PLC controllers, while small and medium series already contain the supply module. User has to determine how much current to take from I/O module to ensure that electrical supply provides appropriate amount of current. Different types of modules use different amounts of electrical current. This electrical supply is usually not used to start external input or output. User has to provide separate supplies in starting PLC controller inputs because then you can ensure so called “pure” supply for the PLC controller. With pure supply we mean supply where industrial environment can not affect it damagingly. Some of the smaller PLC controllers supply their inputs with voltage from a small supply source already incorporated into a PLC.中文翻译:从结构上分,PLC分为固定式和组合式(模块式)两种。

计算机专业外语translation

计算机专业外语translation

A Comparative Study of English-Chinese translationZHAO 2010.5.26u英语n结构紧凑n竹节句法n形合n and, but, if, or, when, who u中文n结构松散n流水句法n意合u一位IT 的科研人员的讲话:“Within about 18 months, more than half of allInternet access will be done by non-PC devices. Ah, that’s a growth from like zero of two years ago or even less than that, ah, to 50% in what will amount to about 3 plus years.”译文:在大约一年半的时间里,对Internet的访问中有一半以上将不是通过PC机进行的。

这种增长将从两年或更短的时间前差不多是零,在大概3年多的时间里上升到50%。

u英语的语序和中文有很大的差别。

尽管可能每个单词你都懂,但是你却听不懂。

u从培养英语的语感做起。

当前影响阅读的主要问题(1)词汇与语法、句法知识的脱节(2)片面追求单词的数量,忽视了单词的多义性(3)不重视句子成分的分析和掌握单词的搭配使用“Put the line where cursor is at topof the display.”“英译中”的原则u“英译中”的最高标准:信、达、雅n“信”,即尊重原文。

n“达”,即译文通达。

n“雅”,即文雅,翻译中最高的要求。

(1) 忠实于原文u 忠实于原文的内容形式。

u “英译中”是一个再创作过程n 不要拘泥于原文的语言形式n 应在正确理解原文内容的基础上,按照中文的语言习惯和表达方式用精练的、优美的语言表达出来n 切忌按英文语句平铺、堆积倒装\u 科技文章与文学作品的翻译是有差别的n 前者强调的是准确性(2)翻译出来的东西要自己明白,也要使别人明白。

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毕业设计(论文)外文资料翻译系别计算机信息与技术系专业计算机科学与技术班级姓名学号外文出处附件 1. 原文; 2. 译文2012年3月History of computingMain article: History of computing hardwareThe first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.Limited-function early computersThe Jacquard loom, on display at the Museum of Science and Industry in Manchester, England, was one of the first programmable devices.The history of the modern computer begins with two separate technologies, automated calculation and programmability, but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. A few devices are worth mentioning though, like some mechanical aids to computing, which were very successful and survived for centuries until the advent of the electronic calculator, like the Sumerian abacus, designed around 2500 BC of which a descendant won a speed competition against a modern desk calculating machine in Japan in 1946, the slide rules, invented in the 1620s, which were carried on five Apollo space missions, including to the moon and arguably the astrolabe and the Antikythera mechanism, an ancient astronomical computer built by the Greeks around 80 BC. The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when. This is the essence of programmability.First general-purpose computersDuring the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers.Alan Turing is widely regarded as the father of modern computer science. In 1936 Turing provided an influential formalisation of the concept of the algorithm andcomputation with the Turing machine, providing a blueprint for the electronic digital computer. Of his role in the creation of the modern computer, Time magazine in naming Turing one of the 100 most influential people of the 20th century, states: "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine".EDSAC was one of the first computers to implement the stored-program (von Neumann) architecture.Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging.The first program-controlled computer was invented by Konrad Zuse, who built the Z3, an electromechanical computing machine, in 1941. The first programmable electronic computer was the Colossus, built in 1943 by Tommy Flowers.George Stibitz is internationally recognized as a father of the modern digital computer. While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the "Model K" (for "kitchen table", on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability.A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult. Notable achievements include. Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.The non-programmable Atanasoff–Berry Computer (commenced in 1937, completed in 1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory. The use of regenerative memory allowed it to be much more compact than its peers (being approximately the size of a large desk or workbench), since intermediate results could be stored and then fed back into the same set of computation elements.The secret British Colossus computers (1943), which had limitedprogrammability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.The U.S. Army's Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.Stored-program architectureSemiconductors and microprocessorsComputers using vacuum tubes as their electronic elements were in use throughout the 1950s, but by the 1960s had been largely replaced by semiconductor transistor-based machines, which were smaller, faster, cheaper to produce, required less power, and were more reliable. The first transistorised computer was demonstrated at the University of Manchester in 1953. In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. By the late 1970s, many products such as video recorders contained dedicated computers called microcontrollers, and they started to appear as a replacement to mechanical controls in domestic appliances such as washing machines. The 1980s witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household.Modern smartphones are fully programmable computers in their own right, and as of 2009 may well be the most common form of such computers in existenc.历史的计算主要文章:计算机硬件的历史在第一次使用“计算机”这个词被记录在1613年,指的是对一个人进行了计算,或计算,与词的意思相同,直到继续20世纪中期。

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