计算机专业外文翻译
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微软Visual Studio
计算机专业外文文献及翻译微软Visual Studio 微软 Visual Studio1 微软 Visual Studio Visual 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(inteqrated development environment)，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 Studio2010)，为支持其他语言，如 MPython和 Ruby 等，可通过安装单独的语言服务。
计算机专业外文翻译(中英文)---HTTP和Servlet的基础知识
附录A 译文HTTP和Servlet的基础知识让我们从定义Web应用程序这一章开始。
我们都看到过一般的客户端应用软件，但怎么样才是一个真正的Web应用程序？然而，它可以被定义为一个用于用户接入的运行在服务器上的程序，通过一个简单，一般用途的客户。
今天，最常见的客户端是一种运行在pc机上的网页浏览器或工作站系统，但其他类型的用户正在迅速加入，如无线PDA ，手机，和其他专门设备。
最崇高目标是从你面前的任何类型的设备上获得你所要的信息和服务。
这意味着同样的简单客户端程序必须能够与许多不同的服务器应用通话，以及应用程序必须能够适用于许多不同类型的客户。
为了满足这一需要，必须制定详细的客户端和服务器相互通信的协义。
这正是超文本传输协议（ HTTP ）的目的。
通信模型所确定的HTTP形式的基础，所有的Web应用程序设计。
基本了解HTTP的关键应用，适合发展中国家的限制范围内的协议，无论哪个服务器端技术的使用。
在本章中，我们看一下最重要的细节的HTTP您需要了解作为一个Web 应用程序开发。
另外一个项目：这本书是用JSP作为服务器端技术。
JSP技术是基于Java Servlet技术。
这两种技术有着大量的术语和概念，所以知道一点servlets将帮助你，即使你开发纯JSP的应用。
要真正理解和使用的全部的JSP ，你需要知道一点servlets 。
因此，我们期待在servlet的基本入在最后一章的这一节。
2.1 HTTP请求/响应模型所有扩展HTTP和基于HTTP协议是基于一个非常简单的通信模式。
其工作原理如下：客户端，通常是一个Web浏览器，发出了一个请求资源的服务器，服务器发回的响应相应的资源（或响应的错误信息，如果它不能处理请求出于某种原因）。
A资源是一些事情的数据，如一个简单的HTML文件逐字返回到浏览器或程序，动态生成的响应。
这种简单的模式意味着三个重要的事实你需要了解：HTTP是一种无状态协议。
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）。
计算机科学与技术 外文翻译 英文文献 中英对照
附件1：外文资料翻译译文大容量存储器由于计算机主存储器的易失性和容量的限制, 大多数的计算机都有附加的称为大容量存储系统的存储设备, 包括有磁盘、CD 和磁带。
相对于主存储器，大的容量储存系统的优点是易失性小，容量大，低成本, 并且在许多情况下, 为了归档的需要可以把储存介质从计算机上移开。
术语联机和脱机通常分别用于描述连接于和没有连接于计算机的设备。
联机意味着，设备或信息已经与计算机连接，计算机不需要人的干预，脱机意味着设备或信息与机器相连前需要人的干预，或许需要将这个设备接通电源，或许包含有该信息的介质需要插到某机械装置里。
大量储存器系统的主要缺点是他们典型地需要机械的运动因此需要较多的时间，因为主存储器的所有工作都由电子器件实现。
1. 磁盘今天，我们使用得最多的一种大量存储器是磁盘，在那里有薄的可以旋转的盘片，盘片上有磁介质以储存数据。
盘片的上面和（或）下面安装有读/写磁头，当盘片旋转时，每个磁头都遍历一圈，它被叫作磁道，围绕着磁盘的上下两个表面。
通过重新定位的读/写磁头，不同的同心圆磁道可以被访问。
通常，一个磁盘存储系统由若干个安装在同一根轴上的盘片组成，盘片之间有足够的距离，使得磁头可以在盘片之间滑动。
在一个磁盘中，所有的磁头是一起移动的。
因此，当磁头移动到新的位置时，新的一组磁道可以存取了。
每一组磁道称为一个柱面。
因为一个磁道能包含的信息可能比我们一次操作所需要得多，所以每个磁道划分成若干个弧区，称为扇区，记录在每个扇区上的信息是连续的二进制位串。
传统的磁盘上每个磁道分为同样数目的扇区，而每个扇区也包含同样数目的二进制位。
（所以，盘片中心的储存的二进制位的密度要比靠近盘片边缘的大）。
因此，一个磁盘存储器系统有许多个别的磁区, 每个扇区都可以作为独立的二进制位串存取，盘片表面上的磁道数目和每个磁道上的扇区数目对于不同的磁盘系统可能都不相同。
磁区大小一般是不超过几个KB; 512 个字节或1024 个字节。
计算机专业毕业设计论文外文文献中英文翻译——java对象
1 . Introduction To Objects1.1The progress of abstractionAll programming languages provide abstractions. It can be argued that the complexity of the problems you’re able to solve is directly related to the kind and quality of abstraction。
By “kind” I mean，“What is it that you are abstracting?” Assembly language is a small abstraction of the underlying machine. Many so—called “imperative” languages that followed （such as FORTRAN，BASIC, and C) were abstractions of assembly language。
These languages are big improvements over assembly language，but their primary abstraction still requires you to think in terms of the structure of the computer rather than the structure of the problem you are trying to solve。
The programmer must establish the association between the machine model (in the “solution space，” which is the place where you’re modeling that problem, such as a computer) and the model of the problem that is actually being solved (in the “problem space,” which is the place where the problem exists). The effort required to perform this mapping, and the fact that it is extrinsic to the programming language，produces programs that are difficult to write and expensive to maintain，and as a side effect created the entire “programming methods” industry.The alter native to modeling the machine is to model the problem you’re trying to solve。
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
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-外文翻译
中文翻译：1 什么是 FlashFlash 是一种创作工具，设计人员和开发人员可使用它来创建演示文稿、应用程序和其它允许用户交互的内容。
Flash 可以包含简单的动画、视频内容、复杂演示文稿和应用程序以及介于它们之间的任何内容。
通常，使用 Flash 创作的各个内容单元称为应用程序，即使它们可能只是很简单的动画。
您可以通过添加图片、声音、视频和特殊效果，构建包含丰富媒体的 Flash 应用程序。
Flash 特别适用于创建通过 Internet 提供的内容，因为它的文件非常小。
Flash 是通过广泛使用矢量图形做到这一点的。
与位图图形相比，矢量图形需要的内存和存储空间小很多，因为它们是以数学公式而不是大型数据集来表示的。
位图图形之所以更大，是因为图像中的每个像素都需要一组单独的数据来表示。
要在 Flash 中构建应用程序，可以使用 Flash 绘图工具创建图形，并将其它媒体元素导入 Flash 文档。
接下来，定义如何以及何时使用各个元素来创建设想中的应用程序。
在 Flash 中创作内容时，需要在 Flash 文档文件中工作。
Flash 文档的文件扩展名为 .fla (FLA)。
Flash 文档有四个主要部分：舞台是在回放过程中显示图形、视频、按钮等内容的位置。
时间轴用来通知 Flash 显示图形和其它项目元素的时间，也可以使用时间轴指定舞台上各图形的分层顺序。
位于较高图层中的图形显示在较低图层中的图形的上方。
库面板是 Flash 显示 Flash 文档中的媒体元素列表的位置。
ActionScript代码可用来向文档中的媒体元素添加交互式内容。
例如，可以添加代码以便用户在单击某按钮时显示一幅新图像，还可以使用 ActionScript 向应用程序添加逻辑。
逻辑使应用程序能够根据用户的操作和其它情况采取不同的工作方式。
Flash 包括两个版本的 ActionScript，可满足创作者的不同具体需要。
有关编写 ActionScript 的详细信息，请参阅"帮助"面板中的"学习 Flash 中的 ActionScript 2.0"。
计算机专业外文翻译 9
译文Apache Struts 2“Apache Struts 2 is an elegant, extensible framework for creating enterprise-ready Java web applications. The framework is designed to streamline the full development cycle, from building, to deploying, to maintaining applications over time” -The Apache Software Foundation.4.1简介Struts是Apache的一个应用于Java Web的网络编程的开源框架。
Struts框架的创造者和发起者是McClanahan。
后来在2002年，Struts框架由Apache软件基金会收购和接管。
Struts 提供给程序员一个易于组织基于JSP和Servlet的HTML格式和Java代码的框架。
Struts1几乎能与所有标准的Java技术和Jakarta配置包协同工作。
然而,随着需求的不断增长，Struts1在网络应用程序暴露出来许多问题,所以为了满足需求，导致Strut2推出,Strut2能更好地为开发者提供服务,如 Ajax、高效开发和可扩展性。
4.1.1 Struts 2的起源自从2000年Apache Struts的发起,Struts框架取得了非常大的成功,被大多数标准所接纳,得到了很大的发展,如果不是这样,哪里会有今天java web程序的成绩。
它的历史,告诉我们Struts是怎样组织JSP和/ Servlets，而提供了固定的框架。
Struts融入server-generated HTML与Javascript,客户端验证,也使得开发比较容易和维护。
随着时间推进的和客户对web 需求扩大,网站应用程序取得硕果累累,Struts1太老了，开始在越来越多的网站前端开发者视野中淡去。
【计算机专业文献翻译】信息系统的管理
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.
计算机科学与技术Java垃圾收集器中英文对照外文翻译文献
中英文资料中英文资料外文翻译文献原文：How a garbage collector works of Java LanguageIf you come from a programming language where allocating objects on the heap is expensive, you may naturally assume that Java’s scheme of allocating everything (except primitives) on the heap is also expensive. However, it turns out that the garbage collector can have a significant impact on increasing the speed of object creation. This might sound a bit odd at first—that storage release affects storage allocation—but it’s the way some JVMs work, and it means that allocating storage for heap objects in Java can be nearly as fast as creating storage on the stack in other languages.For example, you can think of the C++ heap as a yard where each stakes out its own piece of turf object. This real estate can become abandoned sometime later and must be reused. In some JVMs, the Java heap is quite different; it’s more like a conveyor belt that moves forwardevery time you allocate a new object. This means that object storage allocation is remarkab ly rapid. The “heap pointer” is simply moved forward into virgin territory, so it’s effectively the same as C++’s stack allocation. (Of course, there’s a little extra overhead for bookkeeping, but it’s nothing like searching for storage.)You might observ e that the heap isn’t in fact a conveyor belt, and if you treat it that way, you’ll start paging memory—moving it on and off disk, so that you can appear to have more memory than you actually do. Paging significantly impacts performance. Eventually, after you create enough objects, you’ll run out of memory. The trick is that the garbage collector steps in, and while it collects the garbage it compacts all the objects in the heap so that you’ve effectively moved the “heap pointer” closer to the beginning of the conveyor belt and farther away from a page fault. The garbage collector rearranges things and makes it possible for the high-speed, infinite-free-heap model to be used while allocating storage.To understand garbage collection in Java, it’s helpful le arn how garbage-collection schemes work in other systems. A simple but slow garbage-collection technique is called reference counting. This means that each object contains a reference counter, and every time a reference is attached to that object, the reference count is increased. Every time a reference goes out of scope or is set to null, the reference count isdecreased. Thus, managing reference counts is a small but constant overhead that happens throughout the lifetime of your program. The garbage collector moves through the entire list of objects, and when it finds one with a reference count of zero it releases that storage (however, reference counting schemes often release an object as soon as the count goes to zero). The one drawback is that if objects circularly refer to each other they can have nonzero reference counts while still being garbage. Locating such self-referential groups requires significant extra work for the garbage collector. Reference counting is commonly used to explain one kind of g arbage collection, but it doesn’t seem to be used in any JVM implementations.In faster schemes, garbage collection is not based on reference counting. Instead, it is based on the idea that any non-dead object must ultimately be traceable back to a reference that lives either on the stack or in static storage. The chain might go through several layers of objects. Thus, if you start in the stack and in the static storage area and walk through all the references, you’ll find all the live objects. For each reference that you find, you must trace into the object that it points to and then follow all the references in that object, tracing into the objects they point to, etc., until you’ve moved through the entire Web that originated with the reference on the stack or in static storage. Each object that you move through must still be alive. Note that there is no problem withdetached self-referential groups—these are simply not found, and are therefore automatically garbage.In the approach described here, the JVM uses an adaptive garbage-collection scheme, and what it does with the live objects that it locates depends on the variant currently being used. One of these variants is stop-and-copy. This means that—for reasons that will become apparent—the program is first stopped (this is not a background collection scheme). Then, each live object is copied from one heap to another, leaving behind all the garbage. In addition, as the objects are copied into the new heap, they are packed end-to-end, thus compacting the new heap (and allowing new storage to simply be reeled off the end as previously described).Of course, when an object is moved from one place to another, all references that point at the object must be changed. The reference that goes from the heap or the static storage area to the object can be changed right away, but there can be other references pointing to this object Initialization & Cleanup that will be encountered later during the “walk.” These are fixed up as they are found (you could imagine a table that maps old addresses to new ones).There are two issues that make these so-called “copy collectors” inefficient. The first is the idea that you have two heaps and you slosh all the memory back and forth between these two separate heaps,maintaining twice as much memory as you actually need. Some JVMs deal with this by allocating the heap in chunks as needed and simply copying from one chunk to another.The second issue is the copying process itself. Once your program becomes stable, it might be generating little or no garbage. Despite that, a copy collector will still copy all the memory from one place to another, which is wasteful. To prevent this, some JVMs detect that no new garbage is being generated and switch to a different scheme (this is the “adaptive” part). This other scheme is called mark-and-sweep, and it’s what earlier versions of Sun’s JVM used all the time. For general use, mark-and-sweep is fairly slow, but when you know you’re generating little or no garbage, it’s fast. Mark-and-sweep follows the same logic of starting from the stack and static storage, and tracing through all the references to find live objects.However, each time it finds a live object, that object is marked by setting a flag in it, but the object isn’t collected yet.Only when the marking process is finished does the sweep occur. During the sweep, the dead objects are released. However, no copying happens, so if the collector chooses to compact a fragmented heap, it does so by shuffling objects around. “Stop-and-copy”refers to the idea that this type of garbage collection is not done in the background; Instead, the program is stopped while the garbage collection occurs. In the Sun literature you’llfind many references to garbage collection as a low-priority background process, but it turns out that the garbage collection was not implemented that way in earlier versions of the Sun JVM. Instead, the Sun garbage collector stopped the program when memory got low. Mark-and-sweep also requires that the program be stopped.As previously mentioned, in the JVM described here memory is allocated in big blocks. If you allocate a large object, it gets its own block. Strict stop-and-copy requires copying every live object from the source heap to a new heap before you can free the old one, which translates to lots of memory. With blocks, the garbage collection can typically copy objects to dead blocks as it collects. Each block has a generation count to keep track of whether it’s alive. In the normal case, only the blocks created since the last garbage collection are compacted; all other blocks get their generation count bumped if they have been referenced from somewhere. This handles the normal case of lots of short-lived temporary objects. Periodically, a full sweep is made—large objects are still not copied (they just get their generation count bumped), and blocks containing small objects are copied and compacted.The JVM monitors the efficiency of garbage collection and if it becomes a waste of time because all objects are long-lived, then it switches to mark-and sweep. Similarly, the JVM keeps track of how successful mark-and-sweep is, and if the heap starts to becomefragmented, it switches back to stop-and-copy. This is where the “adaptive” part comes in, so you end up with a mouthful: “Adaptive generational stop-and-copy mark-and sweep.”There are a number of additional speedups possible in a JVM. An especially important one involves the operation of the loader and what is called a just-in-time (JIT) compiler. A JIT compiler partially or fully converts a program into native machine code so that it doesn’t need to be interpreted by the JVM and thus runs much faster. When a class must be loaded (typically, the first time you want to create an object of that class), the .class file is located, and the byte codes for that class are brought into memory. At this point, one approach is to simply JIT compile all the code, but this has two drawbacks: It takes a little more time, which, compounded throughout the life of the program, can add up; and it increases the size of the executable (byte codes are significantly more compact than expanded JIT code), and this might cause paging, which definitely slows down a program. An alternative approach is lazy evaluation, which means that the code is not JIT compiled until necessary. Thus, code that never gets executed might never be JIT compiled. The Java Hotspot technologies in recent JDKs take a similar approach by increasingly optimizing a piece of code each time it is executed, so the more the code is executed, the faster it gets.译文：Java垃圾收集器的工作方式如果你学下过一种因为在堆里分配对象所以开销过大的编程语言，很自然你可能会假定Java 在堆里为每一样东西（除了primitives）分配内存资源的机制开销也会很大。
计算机专业毕业设计外文翻译--网站建立的五要素
Five essential elements that the website set up Though the network is total to enter overcast appearance currently, but the power head of the business enterprise construction website back anti- increase. A lot of have farseeing of the business enterprise has already used from the network of the convenience is sexy to arrive construction one self’s website of inevitable. At present is the bran acre that burns money, the concept website drops into in succession of day is exactly also the entity business enterprise that has real strength to get involved a network of hour. But, when the business enterprise decision assurance want to do a website of time, but usually commence from nowhere, don't know need to be throw in how much , need to be usher in what talented person. Under the circumstance of this kind of innumerable in heart, general business enterprise usually according to the mode of the business enterprise publicity material, under the suggestion of the network company or IT technical personnel, the construction becomes the business enterprise website that goes through a format. This kind of business enterprise website that goes through a format, also have it five essential elements: The business enterprise introduction, the contact way, the product(service) introduction, message board, forum. The value of this kind of business enterprise website, the equal to per origin electronics version business enterprise publicity volume, turns over while being provided for interested in customer to need. Therefore, a lot of business enterprises think, throw in several 10000 dollars to do a didn't how much person visit of the website have unworthy. BE a network particularly currently at the time that heat fade away, the general business enterprise can't even consider to throw in several hundred top the ten million imitate the large website of the pure concept.So, how make sure the fixed position that the business enterprise constructs a website?The key figures make policy to the website a real realization from the business enterprise, what is the most decisive decision factor? Isn't the network company or the IT technical personnel's level, is not the funds devotion of the business enterprise either how much, is a website whole plan ability. A lot of business enterprise superstition IT techniques, think as long as invite a professional talented person of IT of arrive the high point, can set up a website. The technical personnel of the IT also is much conceited, the condition of the market also anticipates a rising continuously. Quite good, set up a website not difficult. As long as there is funds, time and condition, anyone’s all can be CEO, CFO, the COO etc. Had no more easy but cheap than network life and the business stage up to now from the thou. This also is why will appear so many websites of cause. But, regardless the technique level is much high, it is just means but isn't a purpose. Have no business enterprise need, technique useless.On the other hand, the business enterprise devotion funds also doesn't necessarily can attain result. There has been currently several 100 up under the circumstance of the website of the ten million, how much a new website really not easy cause people an attention. Regardless website the oneself thinks the meaning is how important, people have already no longer believed the tears and battle cry. People get to the Internet, end is for look for real to oneself useful resources. The resources just is a website to exist of unique have a foothold it originally. Resources of how much decision the size of thewebsite value, this is the truth that the network just knows through the rains and winds of this several years. Depended on an advertisement to try to gain an eyeball to own quantity before, click a rate, popularity etc. the concept has already fall into disfavor, take but the generation registered the customer number, visiting again a rate(turn head a rate), the source information quantity with can participate degree etc. standard. Not only is a risk only investment the house concern these, the website constructor and the plan also should even concern these.Five essential elements of the website construction : Purpose, resources, technique, object, result. The purpose is a need, is the initial problem that the website owns and lets design to understand. The purpose have at present of with long-term of, have public of with implicit of, have direct of with indirect of, have main of with from belong to of, is viable with not viable etc. The purpose relates to the aim or the creativity of the website directly. The creativity of the website is the soul place of the website. Have no creative website like have no the hull of soul. The concept of the resources is very extensive, not the simplicity point the amount of information that the oneself can provide. The funds is the most important composition in the resources. The common saying say: See the vegetables have a meal, measuring form dress. To website, this is the key particularly. The network is a pasta, want to crumple what kind be what kind; the network is a bottomless pit again, how much can burn down. Therefore, the network the earnings mode is the website constructor should be clear early of a debt. For the very first time preparation devotion how much, prepare to support a funds annually how much, provide how much human resource, short date profit and loss the balance point and the long-term earnings target etc. Contents-manpower-funds the threes are closely related. All want to weigh the manpower and the funds resources that can adjust a degree while designing each column eyes in the consideration website. Explicit the purpose and resources be a choice immediately after what technique level. BE the static state a page still a dynamic state page for example, whether the adoption database, the beautiful work result has high and low request, the renewal speed rate of speed and the maintenance way JIAN3 FAN2's etc. Will consider the website service object to participate degree in using convenience. Be also the most important finally, is hope the website attain what result, and how attain this result.The main page is the square one of the website design. Many persons also think the website design are a main page design, the main page level high and low representative website level is high and low. Really such to some extent, so the style, the color layout, the column eyes design, writing of the main page expresses the place that etc. becomes a website to produce a controversy most easily. The so-called sees, a wise man sees ,this top has no everyone forever consistently satisfied of opinion, more temperament styles that is a body to design directly now. Along with to website cognitive transformation, the style of the main page is also transformation usually. But, the main page should be understand to tell customer without any error its purpose, this is affirmative. Now a lot of websites is a particularly large website, all in succession outstanding it owns in the top of the main page of resources, browse with the automatic and more recent contents attraction customer. Therefore, these main pages all imply the dynamic state renewal contents of, then belong to a dynamic state web page technique. And, want generally in consideration of the tasteof the customer(object), arrange in the contents up set up with meticulous care, attain the best result by period. The main page design has two kinds of main trends: Pursue beautiful result(static state) of appearance with pursue a contents abundant result(dynamic state), the former in keeping with contents not much of business enterprise website, the latter suits the comprehensive website that the contents enrich. But some function websites, usually chase the most function outstanding in the main page center, if search the engine and large database.The column purpose the assurance is the website inner part structure of key. Usually forum, message board, the concerning us, website navigate, declare, register area etc. the basic column eyes all put in the next in importance position chain to connect into. The news, main function, main contents, the renewal contents hint etc. puts in the refreshing position. The news and renewal are a website to order, it make, is one of the main meanness that the attraction turns head a rate, is also an essential website necessary of. In browse the eyes, the vitality of the website now of body is here.The website contents cent the function and information two major type. Function have: search engine, the database index, stand to order to navigate, electronic commerce, community, submit manuscript, the self-help web page(free and main page), register, network office etc. The information containment all levels writing page, the data database, and the related chain connect etc. The basis website purpose make sure outstanding what contents, and enrichment and the renewal contents of the technique means and form.The customer(object) community also has important influence to the website design. Face an experienced professional of network for example with face general common customer, its technique carries out a way different, to "usage convenience" the comprehension of this phrase, two community is also different.What is the marking of[with] the website planning success? Be click a rate, popularity, register a number, turn head a rate and lead of consent, great ,contents of customer of abundant, use of convenience, operate of smooth, invest the favor of the house? Also being also incompletely. Successful website should be comprehend to set up the station purpose with accuracy, adjust a limited resources of one degree adequately, fittingly usage suitable technique, serve the usage object expediently, attain expectation result in time. Why want to say convenience with in time? Because network the biggest advantage be fast with the convenience, if the website compares other paths to have no forerunner, even can attain the expectation result a mill- also is nonsense.Construct a website not difficult, is the maintenance and the development that sets up the empress website seldom. Regardless how creativity is novel, the website continues to develop to return a root to still depend on a resources exactly, depending on forever an information total amount of lead the one step, otherwise will be very quickly replace by person. Website depended on a creativity to become famous with one action, its creativity drive after person's mimicry, very quickly the example replace by person is all like that.So, website at set up after, how support with the development?1. The persistence is own special features. The special features is the body of the purpose now, the persistence special features is the purpose that the persistence sets up a station. Usually the transformation special features is disaster to website, being equal tore- construct a new website continuously, how much efforts all would the form notbecome a backlog but throw to the winds. And the manpower funds waste very greatly.2. Concentration the most information’s. Must concentrate all related information’s with maximum limit in own realm. Website like gather city, always merchandise the most places can draw on the most persons. Adopt the whole way collections and display the contents that the website enrich under the possible condition, this principle can never be dated.3. Keep a technical forerunner. As long as the condition allow, must have the technique strength to carry on the technique reformation and exaltation to the website. The website beginning sets up a hair building just, need to be continuously perfect with the correction, reform with exaltation. If don't go together with other to keep to even surmount synchronously on the technique, the website is very quick and then will fade out history stage.4. Control the need of the customer. The customer need is the problem that puts in the first to consider. Among them participate is the most important need of customer. The customer can announce a speech, message, put forward animadversion and construct an opinion general to just participate. Whether website satisfies the need of the customer or not, its participating degree is a main marking.5. Consciousness tracked to run before. The magic power of the network is it continuously creative with surmount. The network constructor must track to flow out continuously to run before consciousness now, and reflect it to own website in time in. This will never be what pursue one astonishing, gain notoriety by shocking statement of result, but the inevitable request that maintenance leads a position.In fine, is the website beginning to set up regardless to still develop over a long period of time, five essential elements all from beginning to end carry through among them. Among them decisive be still a resources-funds, talented person, information, andall participants pay the effort and the strenuous effort of.网站建立的五要素尽管目前网络总体进入低迷状态，但企业建设网站的势头却不退反增。
计算机科学与技术Java垃圾收集器中英文对照外文翻译文献
中英文资料中英文资料外文翻译文献原文：How a garbage collector works of Java LanguageIf you come from a programming language where allocating objects on the heap is expensive, you may naturally assume that Java’s scheme of allocating everything (except primitives) on the heap is also expensive. However, it turns out that the garbage collector can have a significant impact on increasing the speed of object creation. This might sound a bit odd at first—that storage release affects storage allocation—but it’s the way some JVMs work, and it means that allocating storage for heap objects in Java can be nearly as fast as creating storage on the stack in other languages.For example, you can think of the C++ heap as a yard where each stakes out its own piece of turf object. This real estate can become abandoned sometime later and must be reused. In some JVMs, the Java heap is quite different; it’s more like a conveyor belt that moves forwardevery time you allocate a new object. This means that object storage allocation is remarkab ly rapid. The “heap pointer” is simply moved forward into virgin territory, so it’s effectively the same as C++’s stack allocation. (Of course, there’s a little extra overhead for bookkeeping, but it’s nothing like searching for storage.)You might observ e that the heap isn’t in fact a conveyor belt, and if you treat it that way, you’ll start paging memory—moving it on and off disk, so that you can appear to have more memory than you actually do. Paging significantly impacts performance. Eventually, after you create enough objects, you’ll run out of memory. The trick is that the garbage collector steps in, and while it collects the garbage it compacts all the objects in the heap so that you’ve effectively moved the “heap pointer” closer to the beginning of the conveyor belt and farther away from a page fault. The garbage collector rearranges things and makes it possible for the high-speed, infinite-free-heap model to be used while allocating storage.To understand garbage collection in Java, it’s helpful le arn how garbage-collection schemes work in other systems. A simple but slow garbage-collection technique is called reference counting. This means that each object contains a reference counter, and every time a reference is attached to that object, the reference count is increased. Every time a reference goes out of scope or is set to null, the reference count isdecreased. Thus, managing reference counts is a small but constant overhead that happens throughout the lifetime of your program. The garbage collector moves through the entire list of objects, and when it finds one with a reference count of zero it releases that storage (however, reference counting schemes often release an object as soon as the count goes to zero). The one drawback is that if objects circularly refer to each other they can have nonzero reference counts while still being garbage. Locating such self-referential groups requires significant extra work for the garbage collector. Reference counting is commonly used to explain one kind of g arbage collection, but it doesn’t seem to be used in any JVM implementations.In faster schemes, garbage collection is not based on reference counting. Instead, it is based on the idea that any non-dead object must ultimately be traceable back to a reference that lives either on the stack or in static storage. The chain might go through several layers of objects. Thus, if you start in the stack and in the static storage area and walk through all the references, you’ll find all the live objects. For each reference that you find, you must trace into the object that it points to and then follow all the references in that object, tracing into the objects they point to, etc., until you’ve moved through the entire Web that originated with the reference on the stack or in static storage. Each object that you move through must still be alive. Note that there is no problem withdetached self-referential groups—these are simply not found, and are therefore automatically garbage.In the approach described here, the JVM uses an adaptive garbage-collection scheme, and what it does with the live objects that it locates depends on the variant currently being used. One of these variants is stop-and-copy. This means that—for reasons that will become apparent—the program is first stopped (this is not a background collection scheme). Then, each live object is copied from one heap to another, leaving behind all the garbage. In addition, as the objects are copied into the new heap, they are packed end-to-end, thus compacting the new heap (and allowing new storage to simply be reeled off the end as previously described).Of course, when an object is moved from one place to another, all references that point at the object must be changed. The reference that goes from the heap or the static storage area to the object can be changed right away, but there can be other references pointing to this object Initialization & Cleanup that will be encountered later during the “walk.” These are fixed up as they are found (you could imagine a table that maps old addresses to new ones).There are two issues that make these so-called “copy collectors” inefficient. The first is the idea that you have two heaps and you slosh all the memory back and forth between these two separate heaps,maintaining twice as much memory as you actually need. Some JVMs deal with this by allocating the heap in chunks as needed and simply copying from one chunk to another.The second issue is the copying process itself. Once your program becomes stable, it might be generating little or no garbage. Despite that, a copy collector will still copy all the memory from one place to another, which is wasteful. To prevent this, some JVMs detect that no new garbage is being generated and switch to a different scheme (this is the “adaptive” part). This other scheme is called mark-and-sweep, and it’s what earlier versions of Sun’s JVM used all the time. For general use, mark-and-sweep is fairly slow, but when you know you’re generating little or no garbage, it’s fast. Mark-and-sweep follows the same logic of starting from the stack and static storage, and tracing through all the references to find live objects.However, each time it finds a live object, that object is marked by setting a flag in it, but the object isn’t collected yet.Only when the marking process is finished does the sweep occur. During the sweep, the dead objects are released. However, no copying happens, so if the collector chooses to compact a fragmented heap, it does so by shuffling objects around. “Stop-and-copy”refers to the idea that this type of garbage collection is not done in the background; Instead, the program is stopped while the garbage collection occurs. In the Sun literature you’llfind many references to garbage collection as a low-priority background process, but it turns out that the garbage collection was not implemented that way in earlier versions of the Sun JVM. Instead, the Sun garbage collector stopped the program when memory got low. Mark-and-sweep also requires that the program be stopped.As previously mentioned, in the JVM described here memory is allocated in big blocks. If you allocate a large object, it gets its own block. Strict stop-and-copy requires copying every live object from the source heap to a new heap before you can free the old one, which translates to lots of memory. With blocks, the garbage collection can typically copy objects to dead blocks as it collects. Each block has a generation count to keep track of whether it’s alive. In the normal case, only the blocks created since the last garbage collection are compacted; all other blocks get their generation count bumped if they have been referenced from somewhere. This handles the normal case of lots of short-lived temporary objects. Periodically, a full sweep is made—large objects are still not copied (they just get their generation count bumped), and blocks containing small objects are copied and compacted.The JVM monitors the efficiency of garbage collection and if it becomes a waste of time because all objects are long-lived, then it switches to mark-and sweep. Similarly, the JVM keeps track of how successful mark-and-sweep is, and if the heap starts to becomefragmented, it switches back to stop-and-copy. This is where the “adaptive” part comes in, so you end up with a mouthful: “Adaptive generational stop-and-copy mark-and sweep.”There are a number of additional speedups possible in a JVM. An especially important one involves the operation of the loader and what is called a just-in-time (JIT) compiler. A JIT compiler partially or fully converts a program into native machine code so that it doesn’t need to be interpreted by the JVM and thus runs much faster. When a class must be loaded (typically, the first time you want to create an object of that class), the .class file is located, and the byte codes for that class are brought into memory. At this point, one approach is to simply JIT compile all the code, but this has two drawbacks: It takes a little more time, which, compounded throughout the life of the program, can add up; and it increases the size of the executable (byte codes are significantly more compact than expanded JIT code), and this might cause paging, which definitely slows down a program. An alternative approach is lazy evaluation, which means that the code is not JIT compiled until necessary. Thus, code that never gets executed might never be JIT compiled. The Java Hotspot technologies in recent JDKs take a similar approach by increasingly optimizing a piece of code each time it is executed, so the more the code is executed, the faster it gets.译文：Java垃圾收集器的工作方式如果你学下过一种因为在堆里分配对象所以开销过大的编程语言，很自然你可能会假定Java 在堆里为每一样东西（除了primitives）分配内存资源的机制开销也会很大。
计算机专业英语翻译
计算机专业英语翻译随着全球化和数字化时代的到来，计算机技术已经成为我们日常生活中不可或缺的一部分。
为了更好地掌握和运用计算机技术，计算机专业英语翻译变得越来越重要。
本文将探讨计算机专业英语翻译的重要性、技能要求和未来发展趋势。
一、计算机专业英语翻译的重要性计算机专业英语翻译是指将英语或其他语言中的计算机专业技术、理论、应用等信息翻译成中文，帮助人们更好地理解和应用这些技术。
随着全球化的推进，许多计算机技术和应用软件都是英文的，因此，计算机专业英语翻译对于掌握和应用这些技术和软件至关重要。
二、技能要求作为计算机专业英语翻译人员，需要具备以下技能：1、语言技能：需要精通英语和中文两种语言，能够准确地进行翻译和表达。
2、技术知识：需要具备计算机技术的基础知识和相关经验，以便更好地理解原文的含义和语境。
3、专业素养：需要具备高度的责任感和专业素养，保证翻译的准确性和质量。
4、跨文化沟通能力：需要了解不同文化背景下的表达方式和习惯，以便更好地传达原文的含义。
三、未来发展趋势随着和机器翻译技术的发展，计算机专业英语翻译将面临更多的挑战和机遇。
未来，计算机专业英语翻译将更加智能化、自动化和个性化。
随着全球化和数字化时代的深入发展，计算机专业英语翻译的需求也将不断增加。
因此，计算机专业英语翻译人员需要不断提高自己的技能和素质，以适应未来的发展需求。
计算机专业英语翻译是连接技术与语言的桥梁，对于推动全球化和数字化时代的发展至关重要。
作为计算机专业英语翻译人员，需要不断提高自己的技能和素质，以提供更高质量的翻译服务。
计算机专业外文翻译随着全球化和科技的发展，计算机科学领域的知识和技能日益重要。
这不仅限于国内，而是全球的趋势。
为了更好地与世界接轨，我们需要从全球视角来提升我们的计算机科学水平。
因此，外文翻译，尤其是计算机专业的外文翻译显得尤为重要。
一、计算机专业外文翻译的重要性1、知识传递：计算机科学是一个快速发展的领域，每天都有新的研究、新的技术和新的应用出现。
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。
【运行】Java编程语言外文翻译英汉互译中英对照
【关键字】运行外文翻译原文及译文学院计算机学院专业计算机科学与技术班级学号姓名指导教师负责教师Java(programming language)Java is a , , , that is specifically designed to have as few implementation dependencies as possible. It is intended to let application developers "write once, run anywhere" (WORA), meaning that code that runs on one platform does not need to be recompiled to run on another. Java applications are typically to () that can run on any (JVM) regardless of . Java is, as of 2012, one of the most popular programming languages in use, particularly for client-server web applications, with a reported 10 million users. Java was originally developed by at (which has since ) and released in 1995 as a core component of Sun Microsystems' . The language derives much of its from and , but it has fewer facilities than either of them.The original and Java , virtual machines, and were developed by Sun from 1991 and first released in 1995. As of May 2007, in compliance with the specifications of the , Sun relicensed most of its Java technologies under the . Others have also developed alternative implementations of these Sun technologies, such as the and .Java is a set of several products and specifications from (which has since merged with ), that together provide a system for developing and deploying it in a computing environment. Java is used in a wide variety of from and on the low end, to and on the high end. While less common, are sometimes used to provide improved and secure functions while browsing the on .Writing in the is the primary way to produce code that will be deployed as . There are, however, byte code available for other languages such as , JavaScript, , and . Several new languages have been designed to run natively on the (JVM), such as , and . borrows heavily from and , but object-oriented features are modeled after and . Javaeliminates certain low-level constructs such as and has a very simple memory model where every object is and all variables of object types are . Memory management is handled through integrated automatic performed by the JVM.An edition of the Java platform is the name for a bundle of related programs from Sun that allow for developing and running programs written in the programming language. The platform is not specific to any one processor or , but rather an execution engine (called a ) and a compiler with a set of libraries that are implemented for various hardware and operating systems so that Java programs can run identically on all of them. The Java platform consists of several programs, each of which provides a portion of its overall capabilities. For example, the Java compiler, which converts Java source code into Java byte code (an intermediate language for the JVM), is provided as part of the (JDK). The (JRE), complementing the JVM with a , converts intermediate byte code into native machine code on the fly. An extensive set of libraries are also part of the Java platform.The essential components in the platform are the Java language compiler, the libraries, and the runtime environment in which Java intermediate byte code "executes" according to the rules laid out in the virtual machine specification.In most modern (), a large body of reusable code is provided to simplify the programmer's job. This code is typically provided as a set of that applications can call at runtime. Because the Java platform is not dependent on any specific operating system, applications cannot rely on any of the pre-existing OS libraries. Instead, the Java platform provides a comprehensive set of its own standard class libraries containing much of the same reusable functions commonly found in modern operating systems. Most of the system library is also written in Java. For instance, library paints the user interface and handles the events itself, eliminating many subtle differences between how different platforms handle even similar components.The Java class libraries serve three purposes within the Java platform.First, like other standard code libraries, the Java libraries provide the programmer a well-known set of functions to perform common tasks, such as maintaining lists of items or performing complex string parsing. Second, the class libraries provide an abstract interface to tasks that would normally depend heavily on the hardware and operating system. Tasks such as network access and file access are often heavily intertwined with the distinctive implementations of each platform. The and java.io libraries implement an abstraction layer in native OS code, then provide a standard interface for the Java applications to perform those tasks. Finally, when some underlying platform does not support all of the features a Java application expects, the class libraries work to gracefully handle the absent components, either by emulation to provide a substitute, or at least by providing a consistent way to check for the presence of a specific feature.The success of Java and its concept has led to other similar efforts, notably the , appearing since 2002, which incorporates many of the successful aspects of Java. .NET in its complete form (Microsoft's implementation) is currently only fully available on Windows platforms, whereas Java is fully available on many platforms. .NET was built from the ground-up to support multiple programming languages, while the Java platform was initially built to support only the Java language, although many other languages have been made for JVM since..NET includes a Java-like language called (formerly named ) that is incompatible with the Java specification, and the associated class library mostly dates to the old JDK 1.1 version of the language. For these reasons, it is more a transitional language to switch from Java to the .NET platform, than a first class .NET language. Visual J# was discontinued with the release of Microsoft Visual Studio 2008. The existing version shipping with will be supported until 2015 as per the product life-cycle strategy.In June and July 1994, after three days of brainstorming with , the Director of Science for Sun, Gosling, Joy, Naughton, , and , the team re-targeted the platform for the . They felt that with the advent ofgraphical like , the Internet was on its way to evolving into the same highly interactive medium that they had envisioned for cable TV. As a prototype, Naughton wrote a small browser, Web Runner (named after the movie ), later renamed .That year, the language was renamed Java after a search revealed that Oak was used by . Although Java 1.0a was available for download in 1994, the first public release of Java was 1.0a2 with the Hot Java browser on May 23, 1995, announced by Gage at the conference. His announcement was accompanied by a surprise announcement by , Executive Vice President of , that Netscape browsers would be including Java support. On January 9, 1996, the Java Soft group was formed by Sun Microsystems to develop the technology.Java编程语言Java是一种通用的，并发的，基于类的并且是面向东西的计算机编程语言，它是为实现尽可能地减少执行的依赖关系而特别设计的。
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计算机专业外文翻译毕业设计英文翻译作者：XXXThe Delphi Programming LanguageThe Delphi development environment is based on an object-oriented extension of thePascal programming language known as Object Pascal. Most modern programming languagessupport object-oriented programming (OOP). OOP languages are based on three fundamentalconcepts: encapsulation (usually implemented with classes), inheritance, and polymorphism(or late binding).1Classes and ObjectsDelphi is based on OOP concepts, and in particular on the definition of new class types.The use of OOP is partially enforced by the visual development environment, because forevery new form defined at design time, Delphi automatically defines a new class. In addition,every component visually placed on a form is an object of a class type available in or added tothe system library.As in most other modern OOP languages (including Java and C#), in Delphi a class-typevariable doesn't provide the storage for the object, but is only a pointer or reference to theobject in memory. Before you use the object, you must allocate memory for it by creating anew instance or by assigning an existing instance to the variable: varObj1, Obj2: TMyClass;begin // assign a newly created objectObj1 := TMyClass.Create; // assign to an existing objectObj2 := ExistingObject;The call to Create invokes a default constructor available for every class, unless the classredefines it (as described later). To declare a new class data type in Delphi, with some localdata fields and some methods, use the following syntax:typeTDate = classMonth, Day, Year: Integer;procedure SetValue (m, d, y: Integer);function LeapYear: Boolean;第 1 页共 13 页毕业设计英文翻译作者：XXXend;2Creating Components DynamicallyTo emphasize the fact that Delphi components aren't much different from other objects(and also to demonstrate the use of the Self keyword), I've written the CreateComps example.This program has a form with no components and a handler for its OnMouseDown event,which I've chosen because it receives as a parameter the position of the mouse click (unlikethe OnClick event). I need this information to create a button component in that position. Hereis the method's code:procedure TForm1.FormMouseDown (Sender: TObject;Button: TMouseButton; Shift: TShiftState; X, Y: Integer);Var Btn: TButton;beginBtn := TButton.Create (Self);Btn.Parent := Self;Btn.Left := X;Btn.Top := Y;Btn.Width := Btn.Width + 50;Btn.Caption := Format ('Button at %d, %d', [X, Y]);end;The effect of this code is to create buttons at mouse-click positions, as you can see in thefollowing figure. In the code, notice in particular the use of the Self keyword as both theparameter of the Create method (to specify the component's owner) and the value of theParent property.（The output of theexample,which creates Button components at run time第 2 页共 13 页毕业设计英文翻译作者：XXX3EncapsulationThe concept of encapsulation is often indicated by the idea of a "black box." You don'tknow about the internals: You only know how to interface with the black box or use itregardless of its internal structure. The "how to use" portion,called the class interface, allowsother parts of a program to access and use the objects of that class. However, when you usethe objects, most of their code is hidden. You seldom know what internal data the object has,and you usually have no way to access the data directly. Of course, you are supposed to usemethods to access the data, which is shielded from unauthorized access. This is theobject-oriented approach to a classical programming concept known as information hiding.However, in Delphi there is the extra level of hiding, through properties,4PrivateProtectedand PublicFor class-based encapsulation, the Delphi language has three access specifiers: private,protected, and public. A fourth, published, controls run-time type information (RTTI) anddesign-time information, but it gives the same programmatic accessibility as public. Here arethe three classic access specifiers:, The private directive denotes fields and methods of a class thatare not accessible outsidethe unit that declares the class., The protected directive is used to indicate methods and fields with limited visibility. Onlythe current class and its inherited classes can access protected elements. More precisely,only the class, subclasses, and any code in the same unit as the class can access protectedmembers。