计算机专业VB类通用外文翻译及文献

Visual Basic language and arithmetic

The United States launched the Microsoft Visual Basic (may be referred to VB, is the latest version of the current VB 2008 Beta2 (VB9 Chinese version.

Visual meaning the visual, visible, referring to the development of operating systems like windows graphical user interface (Graphic User Interface, GUI method, it does not need to prepare a large number code to describe the appearance of the interface elements and location, as long as the pre - The establishment of good drag and drop objects on the screen corresponding to the location.

Basic is actually an abbreviation of the phrase; this phrase is Beginners all-purpose symbolic instruction code, the Chinese meaning "to the initial directive GM symbol code language."

Visual Basic learning, Professional Edition and Enterprise Edition versions to meet the different needs of the development. Study and apply to the ordinary version of the majority of learners and the use of Visual Basic development of the general staff of Windows applications, but; professional version for computer professional development of staff, including the study of functional version of the full content control and Internet development tools such as advanced features ,Enterprise contain not only all the professional version of the content, there are automated tools such as Component Manager, professional programmers to make the development of a powerful group essence of distributed applications.

Visual Basic

Section 1 the summary of Visual Basic

Microsoft Visual Basic,( abbreviate VB as tool the most of application program one of under Windows operating platform. No matter beginner or professional developer, VB has all offered a whole set of tools to them, Development application program that it can

be relaxed and convenient. So VB as most computer first-selected the ABC of programming language of beginner.

" Visual" mean method to adopt visual user of development figure interface (GUI, need and write a large number of code go and describe interface appearance and position of element seldom, Tow and show controlling part that need corresponding position to get screen can help figure design interface, user of figure,; " Basic" means BASIC language, because VB is developed on the basis of already existing BAISC language.

VB is a kind of programming language in common use of Microsoft, It, including VBA of the numerous Windows application software use VB language in Microsoft Excel, Microsoft Accessed., For users to carry on the secondary development; Make web page use more VBScript script language sub collection of VB too at present.

Utilize data of VB visit characteristic user can establish the data base to most data base forms including Microsoft SQL Server and other enterprises data base With the application program of front, and adjustable service end part. Utilize ActiveX(TM technology, VB can use word processor, electronic data list he Windows function that application program offers extremely, Excel of Microsoft,, Word of Microsoft,, Even can use by VB specialty edition or enterprise application program and target that

edition establish directly.

The procedure that users established finally is a real .EXE file , can issue freely .

VB offer study edition, the specialty edition and enterprise edition, use to satisfied with different development demands. Study edition make programming personnel develop Windows and Windows application program of NT very easily. The specialty edition has offered the developing instrument with complete function to programming personnel of the specialty, Include studying all functions of edition in the specialty edition. Enterprise edition allow the professional personnel to establish strong distributed

application program in the form of group. It includes all characteristics of the specialty edition. So can choose different editions according to different needs.

Section 2 integrated development environments

Integrated environment of VB call IDE, made up of a lot of parts , include title board, menu fence, tool fence, controlling part case, And window body window, engineering management device window, attribute window, code window and window body overall arrangement window body overall arrangement, etc. of designing etc.. Have covered all functions, such as design which develops the application program, editting, compiling and debugging, etc..

In VB, the application program calls the project too. When start VB and open a new project for the first time, can see and pursue integrated development environment interface that show.

Visual Basic Integrated development environment

VB come and organize development of application program through project, use project come and manage and form files of application program. One project uses the environment to make up by several window bodies, standard module generally. The system manages project through the project menu, for instance add the window body, quote . System allow turn on and manage a lot of projects besides.

Section 3 Visual Basic language brief introductions

Basic use and do the elementary high-level language that used often most. Its full name is Beginner' s All-purpose Symbolic Instruction Code, abbreviate as BASIC. As its name suggests, Basic one specially for language that beginner design, because it easy to learn easy to know, So the body is popular. Early Basic language to belong to and solve translating type, so can carry out line by line , So it can see the result carried out at once , this is a very convenient design for beginner. But it have concept of structure either, one

that is in procedure maintain and management have as much as other language problems. But back-end Basic correct shortcoming of the above (such as Quick Basic, make it may used for and develop the large-scaler procedure too.

The language is the basic composition, which forms VB procedure. VB has stipulated the form of sentences and function.

Grammar:

The sentence defines incantations [Sentence body]

Sentence define agree with and used in fixed function of sentence, sentence body appoint concrete content or want concrete operation that carry out of sentence. All set of sentence VB language, carry on with VB sentence organic association finish a

certain specific function the procedure. Interface + procedure can solve a certain application problem.

VB application program code window write in" code editing machine" generally. " editing machine of code" is like the word processing software of a piece of height specialization, there are many easies function of writing VB code, Pursue to show [Example Ex-Hello ]In" code editing machine" code that window written.

“Editing machine of code” window

Section 4 develop the application program with Visual Basic

Use VB programming, design appearance of application program first generally, write every target procedure code or other treatment procedure of incident respectively, Work of programming should be light more.

The procedure of establishing the application program is as follows:

Establish application program interface

The interface is the mutual bridge of user and procedure, Generally formed of window body and vision frame of the button, menu, text frameset. with standard WINDOWS interface of application program that VB establish. Require according to function of procedure and user and need of information interchange of procedure, Come to confirm that need those targets , plan the overall arrangement of the interface.

2. Design by each attributes of target in interface

Demand and set up each attribute of target such as appearance, name,, size of targeted. according to interface of planning.

Most attribute person who fetch can set up through the attribute window when design already, Too can set up revising when operating in procedure through programming in procedure code. Have the targets respond programming by procedure code

3. Respond procedure code of programming target

Interface determine appearance of procedure only, design window add codes through" code editing machine" soon after the interface, Realize some make the tasks, such as responding, information processing,etc. after accepting external message, Add code , realize some response, information processing that make after accepting external information task, As editor's window of code pursued shows add codes “code editing machine” wi ndow

4. Keep project

One VB procedure one project, at the time of designing a application program, system will set up one be expanded and called. Project vbp, project all relevant information of project set up this, Keep project keep associated documents of project this

at the same time. For example the window body produced when design interfaces is kept and being expanded and being called. Frm sum. In the window body of foxfire. At the time of opening a project( file, this project relevant files load at the same time.

5. Operate and debugged by procedure

Operate the procedure thoroughpin operate" selecting in the menu, when the mistake appears, VB system can offer information prompt can looked for and get rid

of the mistake thoroughpin debug" within operate" menus too.

6. Can produce by executive program

For make procedure can break away from VB environment, order to become next life through" file"" producing project 1.exe" of menu but executive program (eyeful, Can carry out this after this. In produce, + executive program, and then through install guide bale all associated documents, Can run independently after installation under the environment of windows 9 x/2000 as a software product.

In computer system's any software, is by the every large or small each kind of software constituent constitution, defers to the specific algorithm to realize respectively, the algorithm quality direct decision realizes the software performance fit and unfit quality. Designs the algorithm with any method, what resources designs the algorithm to need, requires how many running time, how many storage space, how to determine an algorithm the quality, when realizes a software, is must give to solve. In computer system's operating system, the language compiling system, the database management system as well as in various computer application system's software, must use each one concrete algorithm to realize. Therefore, the algorithm design and the analysis are the computer science and a technical core question.

The algorithm is the problem-solving step, we may define the algorithm Cheng Jie a determination class question the random one special method. In the computer science, the

algorithm needs to use the computer algorithmic language to describe, the algorithm represents with the computer solves a kind of question precisely, the effective method. The algorithm construction of data = procedure, solves one to assign may calculate or the solvable question, the different person may compile the different procedure, solves the identical problem, here has two problems: First, with computational method close related algorithm question; Second, programming technical question. Between the algorithm and the procedure has the close relationship. The algorithm is a group has the poor rule, they had stipulated solves some specific type question a series of operations, is to the problem solving plan accurate and the complete description. Formulates an algorithm, generally must pass through stages and so on design, confirmation, analysis, code, test, debugging, time. To algorithm study including five aspect contents:① Design algorithm. The algorithm design work is impossible completely the automation, should study the understanding already by the practice to prove that was the useful some basic algorithm design method, these basic design method was not only suitable for the computer science, moreover was suitable for domains and so on electrical engineering, operations research;②Expresses the algorithm. The description algorithm's method has many kinds of forms, for example the natural language and the algorithmic language, have the suitable environment and the characteristic respectively;③Confirms the algorithm. The algorithm confirmed the goal is causes the people to believe firmly that this algorithm can work unmistakably correctly, namely this algorithm has the circularity. The correct algorithm describes with the computer algorithmic language, constitutes the computer program, the computer program moves on the computer, obtains the

algorithm operation result;④ Parsing algorithm. The algorithmic analysis is requires how many computing time and the storage space to an algorithm makes the quota the analysis. The parsing algorithm may forecast that what environment this algorithm does suit in moves effectively, to solves the identical question different algorithm validity to make the comparison;⑤ Confirmation algorithm. With machine language description algorithm whether can calculate effectively, reasonable, must carry on the test to the

procedure, the test order work and makes the space and time distribution map by the debugging to be composed.

But the algorithm has certain characteristic, it includes:①Determinism. Algorithm each kind of operation must have the determination significance, this kind of operation should carry out what kind of movement should not to have the ambiguity, the goal is clear;②Effectiveness. Requests the operation which in the algorithm waits for realizing is basic, each kind of operation can at least completes in the principle by the human with the paper and the pen in the limited time;③ Input. An algorithm has 0 or the many inputs, before the algorithm operation starts gives the algorithm to need the data the starting value, these inputs are from the specific object set;④Output. Does for the algorithm operation result, an algorithm has or many outputs, the output has some kind of specific relational quantity with the input;⑤ Has poor. An algorithm always after carrying out had the poor step operation has terminated, namely this algorithm was may reach.

Satisfies a first four characteristic group of rule not to be able to be called the algorithm, can only be called the computational process, the operating system is a computational process example, the operating system uses for to manage the computer resources, controls the manufacture industry movement, when has not made industry the movement, the computational process does not stop, but is at the waiting status.

The algorithm complexity is the algorithm efficiency measure, when appraises the algorithm performance, the complexity is an important basis. The algorithm complex degree with moves computer resources how many which this algorithm needs related, needs the resources are more, indicated that this algorithm the complexity is higher; Needs the resources are less, indicated that this algorithm the complexity is lower.

The spatial resources, which computer’s resources, operate most importantly, needs the time which and the stored routine and the data need, the algorithm complexity has division time complexity and the spatial complexity.

The algorithm carries out the operation on the computer, needs the data which certain storage space depositing description algorithm the procedure and the algorithm need, the computer completes the operation task to require certain time. The procedure which writes according to the different algorithm places when on the computer operates, needs the time and the space are different, the algorithm complexity is needs the time and the spatial one kind of measure to the algorithm operation. The different computer its operating speed difference is very big, is weighing an algorithm the complexity to note this point.

Regarding question, which assigns willfully, a profitable target which designs,

the complex low algorithm is as far as possible when designs algorithm considered. Moreover, when the question, which assigns already when has many kinds of algorithms, an important criterion which choice complexity low, is when selects algorithm should follow. Therefore, the algorithm complex analysis or selects to the algorithm design has the important guiding sense and the use value.

When discussion algorithm complexity, two questions need to clarify:

(1 An algorithm's complexity expresses with what kind of quantity;

(2 How to calculate one to assign the algorithm the complexity. After finding solves

a question the algorithm, is this algorithm realization, as for whether could find the method which realized, was decided in the algorithm circularity and the computation complexity, whether this question did have the solution algorithm, whether to provide the time resources which and the spatial resources the algorithm needed.

Visual Basic 语言与算法

1991年,美国微软公司推出了Visual Basic(可简称VB,目前的最新版本是VB 2008 Beta2(VB9中文版。

Visual 意即可视的、可见的,指的是开发像windows操作系统的图形用户界面(Graphic User Interface,GUI的方法,它不需要编写大量代码去描述界面元素的外观和位置,只要把预先建立好的对象拖放到屏幕上相应的位置即可。

Basic 实际上是一个短语的缩写,这个短语就是 Beginners all_purpose symbolic instruction code ,其中文意思为“初始者通用符号指令代码语言”。Visual Basic有学

习版、专业版和企业版三种版本,以满足不同的开发需要。学习版适用于普通学习者及大多数使用Visual Basic开发一般Windows应用程序的人员,但是;专业版适用于计算机专业开发人员,包括了学习版的全部内容功能以及Internet控件开发工具之类的高级特性;企业版除包含专业版全部的内容外,还有自动化构件管理器等工具,使得专业编程人员能够开发功能强大的组骨子里分布式应用程序。

Visual Basic

第1节Visual Basic的概述

Microsoft Visual Basic(简称VB是在Windows操作平台下设计应用程序的最速度、最简捷的工具之一。不论是初学者还是专业开发人员,VB都为他们提供了一整套的工具,可以轻松方便的开发应用程序。因此,VB一直被作为大多数电脑初学者

的首选入门编程语言。

“Visual”指的是采用可视化的开发图形用户界面(GUI的方法,一般不需要编写

大量代码去描述界面元素的外观和位置,而只要把需要的控件拖放到屏幕上的相应位置即可方便图形设计图形用户界面;“Basic”指的是 BASIC语言,因为VB是在原有的BAISC语言的基础上发展起来的。

VB是 Microsoft的一种通用程序设计语言,它包括在 Microsoft Excel、Microsoft Access等众多Windows应用软件中的VBA都使用VB语言,以供用户进行二次开发;目前制作网页使用较多的VBScript脚本语言也是VB的子集。

利用VB的数据访问特性用户可以对包括 Microsoft SQL Server和其他企业数据库在内的大部分数据库格式创建数据库和前端应用程序,以及可调整的服务端部

件。利用ActiveX(TM技术,VB可使用 Microsoft Word字处理器、Microsoft Excel 电子数据表极其他Windows应用程序提供的功能,甚至可直接

使用由VB专业版或企业版创建的应用程序和对象。

用户最终创建的程序是一个真正的.EXE文件,可以自由发布。

VB提供了学习版,专业版和企业版,用以满足不同的开发需求。学习版使编程人员很容易地开发Windows和Windows NT的应用程序。专业版为专业编程人员提供了功能完备的开发工具,专业版中包含了学习版的所有功能。企业版允许专业人员以小组的形式来创建强大的分布式应用程序。它包括专业版的所有的特性。所以可以根据不同的需要来选择不同的版本。

第2节集成开发环境

VB的集成环境或称IDE,由多个部分组成,包含了标题栏、菜单栏、工具栏、控件箱,以及窗体设计器窗口、工程管理器窗口、属性窗口、代码窗口和窗体布局窗体布局等。覆盖了开发应用程序的设计、编辑、编译和调试等所有功能。

在VB中,应用程序也称工程。当第一次启动VB并打开一个新工程时,可以看到如图所示的集成开发环境界面。

Visual Basic 集成开发环境

VB通过工程来组织应用程序的开发,使用工程来管理构成应用程序的所有文件。一个工程一般由若干个窗体、标准模块以及应用环境组成。系统通过工程菜单来对工程进行管理,如添加窗体、引用等。系统允许同时打开和管理多个工程。

第3节Visual Basic语言简介

Basic是最常被用来做入门使用的高级语言。它的全名是Beginner’s All-purpose Sumbolic Instruction Code,简称为 BASIC。顾名思义,Basic 就是一种专为初学者设计的语言,因其易学易懂,所以身受欢迎。早期的Basic 语言都是属于解译式

的,因此可以一行一行地执行,所以它可以立刻看到执行的结果,对初学者来说这是很方便的设计。不过它也因此没有结构化的概念,在程序的维护及管理上比起其他语言困难许多。不过在后期的Basic则改正了以上的缺点(如Quick Basic,使得它也可以用来开发较大型的程序。

语言是构成VB程序的基本成分。VB规定了语句格式和功能。

语法:

语句定义符[语句体]

语句定义符用于规定语句的功能,语句体指定语句的具体内容或要执行的具体操作。所有语句的集合就是VB语言,用VB语句进行有机组合完成某个特定功能就是程序。界面+程序就能解决某个应用问题。

VB应用程序代码一般在“代码编辑器”窗口编写。“代码编辑器”像是一个高度专门化的字处理软件,有很多便于编写VB代码的功能,图所示为[例Ex-Hello]在“代码编辑器”窗口编写的代码。

“代码编辑器”窗口

第4节用Visual Basic开发应用程序

使用VB编程,一般先设计应用程序的外观,然后再分别编写各对象事件的程序代码或其他处理程序,编程的工作要轻松多。

创建应用程序的步骤如下:

1.创建应用程序界面

界面是用户和程序交互的桥梁,用VB创建的标准的WINDOWS应用程序的界面一般由窗体和按钮、菜单、文本框的图象框等构成。根据程序的功能要求和用户与程序之间的信息交流的需要,来确定需要那些对象,规划界面的布局。

2.设计界面上各个对象的属性

根据规划的界面要求设置各个对象的属性,比如对象的外貌、名称、颜色、大小等。

大多数属性取值既可以在设计时通过属性窗口来设置,也可以在程序代码中通过编程在程序运行时设置修改。

3.编程对象响应的程序代码

界面仅仅决定了程序的外观,设计完界面后就要通过“代码编辑器”

窗口来添加代码,实现一些在接受外界信息后作出响应、信息处理等任务,添加代码,实现一些在接受外界信息后作出的响应、信息处理等任务,添加代码如图的代码编辑窗口所示

“代码编辑器”窗口

4.保存工程

一个VB程序就是一个工程,在设计一个应用程序时,系统会建立一个扩展名为.vbp的工程文件,工程文件包含了该工程所建立的所有文件的相关信息,保存工程就同时保存了该工程的所有相关文件。比如当设计界面时产生的窗体保存在扩展名为.frm和.frx的窗体文件中。在打开一个工程(文件时,该工程有关的所有文件同时被装载。

5.行和调试程序

通过“运行”菜单中的选项来运行程序,当出现错误时, VB系统可以提供信息提示也可通过“调试”和“运行”菜单来查找和排除错误。

6.生成可执行程序

为了使程序可以脱离VB环境,通过“文件”菜单中的“生成工程1.exe”命令来生成可执行程序(.exe文件,此后即可直接执行该文件。在生成可+执行程序后,再通过安装向导将所有相关文件打包,就可以作为一个软件产品在windows 9x/2000 环境下安装后独立运行

VB的数据库编程方面按其难易程度可分为三类(由易到难;

●使用数据库控制项和绑定控制项

●使用数据库对象变量进行编程

●直接调用ODBC2.0API

在使用VB进行数据库编程时,通常,会首先选择三种基本方法之一来进行数据库应用程序的方案设计, 现在就将以上三种设计方法的适应范围及其优缺点进行一个比较。

1 使用数据库控制项和绑定控制项

1.1优点

它是三种方法中编码量最小的

不必了解CDBC2.0API的细节

允许使用标准的和第三方厂商制订的控制项

简化了错误处理

支持所有的动态集方法及属性

1.2缺点

不能存取快照对象(snapshop对象或表格对象(都属于记录集对象

不能存取数据库集合,比如表定义(TableDefs字段(Fieds,索引

( Indexes及查询定义(QueryDefs

只能存取部分ODBC2.0管理函数

不能进行真正的事务处理

有限的错误诊断功能

1.3应用

对中小规模的数据库表(通常少于一千条记录只进行简章的浏览操作

基本SQL查询所对应的结果集长度有限(通常结果集的记录数小于一百, 这些记录从一个或两个长度有限的表中检索出来

应用程序的数据输入/输出项较少(通常只涉及一个或两个长度有限的表、

并且表中的字段数在10个左右且不具有关系完整性限制

2 使用数据库对象变量进行编程

2.1 优点

可以在程序中存取ODBC2.0的管理函数

可以控制多种记录集类型:Dynaset、Snapshop及Table记录集合对象

可以存取存储过程和查询动作

可以存取数据库集合对象,例如TableDefs、Fields、Indexes及QueryDefs 具有真正的事务处理能力 , 包括启动事务 ( Begintrans 、提交事务(CommitTrans及回滚事务(Rollback

2.2 缺点

比使用数据控制项的方法编码量较大

只能进行间接的错误处理和错误恢复

对每个数据库操作没有细粒度的控制

对结果集和包含结果集的内丰资源的操作受到限制

同直接使用ODBC2.0API函数的方法相比性能较低

2.3 应用

应用程序需要在执行期间动态地建立表、字段及索引.

应用程序涉及同步更新几张表(但在逻辑上保持一致性的复杂事务

应用程序使用结果集而不是Dynaset的窗体(FORMS,例如Snapshots或Tables,这里是设计要考虑的关键

应用程序的表非常大,多于1000条记录

应用程序具有复杂的数据输入/输出项,它涉及许多内部相关的字段并且包括数据库参照完整性或一致性规则

应用程序需要执行一些额外的操作和对结果集的查询后处理, 尤其是需要

很高的数据格式化显示

应用程序需要利用复杂的ODBC管理功能以选择、配置、校验及建立各种数据源

应用程序需要在执行期间“显示”数据库的基本结构

应用程序需要使用复杂的多码索引方式来检索或更新记录

3 直接调用ODBC2.0API

3.1 优点

可以直接参与结果集的开发、管理及规范化

对结果集游标提供了更多的控制,并且提供了更多的游标类型和执行动作

能够确定ODBC驱动程序及SQL的一致性级别

可以更好地控制Windows的执行调度及资源利用

其他方面同其他方法差不多,因此这种方法很可能具有最好的性能

3.2 缺点

较其他两种方法需要大量的代码

代码复杂并且要求程序员具有编制API调用的经验

在网络上Visual Basic运行期间库的错误处理缺乏安全性,因此代码运行期间出现的错误所造成的后果会非常严重

3.3 应用

如果系统环境为客户机/服务器模式下的大规模多用户环境,那么应用程序必须都能够准确地解决可能出现的系统错误和失败

应用程序强调资源使用,这里如何对内存、网络服务器资源进行直接控制是首要的考虑因素

应用程序使用超大规模数据库,例如数据库表可能包含几万或几十万条记录计算机系统中的任何软件,都是由大大小小的各种软件组成部分构成,各自按照特定的算法来实现,算法的好坏直接决定所实现软件性能的优劣。用什么方法来设计算法,所设计算法需要什么样的资源,需要多少运行时间、多少存储空间,如何判定一个算法的好坏,在实现一个软件时,都是必须予以解决的。计算机系统中的操作系统、语

言编译系统、数据库管理系统以及各种各样的计算机应用系统中的软件,都必须用一个个具体的算法来实现。因此,算法设计与分析是计算机科学与技术的一个核心问题。

算法是解题的步骤,我们可以把算法定义成解一确定类问题的任意一种特殊的方法。在计算机科学中,算法要用计算机算法语言描述,算法代表用计算机解一类问题的精确、有效的方法。算法+数据结构=程序,求解一个给定的可计算或可解的问题,不同的人可以编写出不同的程序,来解决同一个问题,这里存在两个问题:一是与计算方法密切相关的算法问题;二是程序设计的技术问题。算法和程序之间存在密切的关系。算法是一组有穷的规则,它们规定了解决某一特定类型问题的一系列运算,是对解题方案的准确与完整的描述。制定一个算法,一般要经过设计、确认、分析、编码、测试、调试、计时等阶段。对算法的学习包括五个方面的内容:①设计算法。算法设计工作是不可能完全自动化的,应学习了解已经被实践证明是有用的一些基本的算法设计方法,这些基本的设计方法不仅适用于计算机科学,而且适用于电气工程、运筹学等领域;②表示算法。描述算法的方法有多种形式,例如自然语言和算法语言,各自有适用的环境和特点;③确认算法。算法确认的目的是使人们确信这一算法能够正确无误地工作,即该算法具有可计算性。正确的算法用计算机算法语言描述,构成计算机程序,

计算机程序在计算机上运行，得到算法运算的结果；④分析算法。算法分析是对一个算法需要多少计算时间和存储空间作定量的分析。分析算法可以预测这一算法适合在什么样的环境中有效地运行，对解决同一问题的不同算法的有效性作出比较；⑤验证算法。用计算机语言描述的算法是否可计算、有效合理，须对程序进行测试，测试程序的工作由调试和作时空分布图组成。而算法具有一定的特性，它包括：①确定性。算法的每一种运算必须有确定的意义，该种运算应执行何种动作应无二义性，目的明确；②能行性。要求算法中有待实现的运算都是基本的，每种运算至少在原理上能由人用纸和笔在有限的时间内完成；③输入。一个算法有 0 个或多个输入，在算法运算开始之前给出算法所需数据的初值，这些输入取自特定的对象集合；④输出。作为算法运算的结果，一个算法产生一个

或多个输出，输出是同输入有某种特定关系的量；⑤有穷性。一个算法总是在执行了有穷步的运算后终止，即该算法是可达的。满足前四个特性的一组规则不能称为算法，只能称为计算过程，操作系统是计算过程的一个例子，操作系统用来管理计算机资源，控制作业的运行，没有作业运行时，计算过程并不停止，而是处于等待状态。算法的复杂性是算法效率的度量，在评价算法性能时，复杂性是一个重要的依据。算法的复杂性的程度与运行该算法所需要的计算机资源的多少有关，所需要的资源越多，表明该算法的复杂性越高；所需要的资源越少，表明该算法的复杂性越低。计算机的资源，最重要的是运算所需的时间和存储程序和数据所需的空间资源，算法的复杂性有时间复杂性和空间复杂性之分。算法在计算机上执行运算，需要一定的存储空间存放描述算法的程序和算法所需的数据，计算机完成运算任务需要一定的时间。根据不同的算法写出的程序放在计算机上运算时，所需要的时间和空间是不同的，算法的复杂性是对算法运算所需时间和空间的一种度量。不同的计算机其运算速度相差很大，在衡量一个算法的复杂性要注意到这一点。对于任意给定的问题，设计出复杂性尽可能低的算法是在设计算法时考虑的一个重要目标。另外，当给定的问题已有多种算法时，选择其中复杂性最低者，是在选用算法时应遵循的一个重要准则。因此，算法的复杂性分析对算法的设计或选用有着重要的指导意义和实用价值。

外文翻译

Load and Ultimate Moment of Prestressed Concrete Action Under Overload-Cracking Load It has been shown that a variation in the external load acting on a prestressed beam results in a change in the location of the pressure line for beams in the elastic range.This is a fundamental principle of prestressed construction.In a normal prestressed beam,this shift in the location of the pressure line continues at a relatively uniform rate,as the external load is increased,to the point where cracks develop in the tension fiber.After the cracking load has been exceeded,the rate of movement in the pressure line decreases as additional load is applied,and a significant increase in the stress in the prestressing tendon and the resultant concrete force begins to take place.This change in the action of the internal moment continues until all movement of the pressure line ceases.The moment caused by loads that are applied thereafter is offset entirely by a corresponding and proportional change in the internal forces,just as in reinforced-concrete construction.This fact,that the load in the elastic range and the plastic range is carried by actions that are fundamentally different,is very significant and renders strength computations essential for all designs in order to ensure that adequate safety factors exist.This is true even though the stresses in the elastic range may conform to a recognized elastic design criterion. It should be noted that the load deflection curve is close to a straight line up to the cracking load and that the curve becomes progressively more curved as the load is increased above the cracking load.The curvature of the load-deflection curve for loads over the cracking load is due to the change in the basic internal resisting moment action that counteracts the applied loads,as described above,as well as to plastic strains that begin to take place in the steel and the concrete when stressed to high levels. In some structures it may be essential that the flexural members remain crack free even under significant overloads.This may be due to the structures’being exposed to exceptionally corrosive atmospheres during their useful life.In designing prestressed members to be used in special structures of this type,it may be necessary to compute the load that causes cracking of the tensile flange,in order to ensure that adequate safety against cracking is provided by the design.The computation of the moment that will cause cracking is also necessary to ensure compliance with some design criteria. Many tests have demonstrated that the load-deflection curves of prestressed beams are approximately linear up to and slightly in excess of the load that causes the first cracks in the tensile flange.(The linearity is a function of the rate at which the load is applied.)For this reason,normal elastic-design relationships can be used in computing the cracking load by simply determining the load that results in a net tensile stress in the tensile flange(prestress minus the effects of the applied loads)that is equal to the tensile strength of the concrete.It is customary to assume that the flexural tensile strength of the concrete is equal to the modulus of rupture of the

英文文献翻译

中等分辨率制备分离的 快速色谱技术 W. Clark Still,* Michael K a h n , and Abhijit Mitra Departm(7nt o/ Chemistry, Columbia Uniuersity,1Veu York, Neu; York 10027 ReceiLied January 26, 1978 我们希望找到一种简单的吸附色谱技术用于有机化合物的常规净化。这种技术是适于传统的有机物大规模制备分离，该技术需使用长柱色谱法。尽管这种技术得到的效果非常好，但是其需要消耗大量的时间，并且由于频带拖尾经常出现低复原率。当分离的样本剂量大于1或者2g时，这些问题显得更加突出。近年来，几种制备系统已经进行了改进，能将分离时间减少到1-3h，并允许各成分的分辨率ΔR f≥（使用薄层色谱分析进行分析）。在这些方法中，在我们的实验室中，媒介压力色谱法1和短柱色谱法2是最成功的。最近，我们发现一种可以将分离速度大幅度提升的技术，可用于反应产物的常规提纯，我们将这种技术称为急骤色谱法。虽然这种技术的分辨率只是中等（ΔR f≥），而且构建这个系统花费非常低，并且能在10-15min内分离重量在的样本。4 急骤色谱法是以空气压力驱动的混合介质压力以及短柱色谱法为基础，专门针对快速分离，介质压力以及短柱色谱已经进行了优化。优化实验是在一组标准条件5下进行的，优化实验使用苯甲醇作为样本，放在一个20mm*5in.的硅胶柱60内，使用Tracor 970紫外检测器监测圆柱的输出。分辨率通过持续时间（r）和峰宽（w,w/2）的比率进行测定的（Figure 1），结果如图2-4所示，图2-4分别放映分辨率随着硅胶颗粒大小、洗脱液流速和样本大小的变化。

外文翻译 - 英文

The smart grid Smart grid is the grid intelligent (electric power), also known as the "grid" 2.0, it is based on the integration, high-speed bidirectional communication network, on the basis of through the use of advanced sensor and measuring technology, advanced equipme nt technology, the advanced control method, and the application of advanced technology of decision support system, realize the power grid reliability, security, economic, efficient, environmental friendly and use the security target, its main features include self-healing, incentives and include user, against attacks, provide meet user requirements of power quality in the 21st century, allow all sorts of different power generation in the form of access, start the electric power market and asset optimizatio n run efficiently. The U.S. department of energy (doe) "the Grid of 2030" : a fully automated power transmission network, able to monitor and control each user and power Grid nodes, guarantee from power plants to end users among all the nodes in the whole process of transmission and distribution of information and energy bi-directional flow. China iot alliance between colleges: smart grid is made up of many parts, can be divided into:intelligent substation, intelligent power distribution network, intelli gent watt-hourmeter,intelligent interactive terminals, intelligent scheduling, smart appliances, intelligent building electricity, smart city power grid, smart power generation system, the new type of energy storage system.Now a part of it to do a simple i ntroduction. European technology BBS: an integration of all users connected to the power grid all the behavior of the power transmission network, to provide sustained and effective economic and security of power. Chinese academy of sciences, institute of electrical: smart grid is including all kinds of power generation equipment, power transmission and distribution network, power equipment and storage equipment, on the basis of the physical power grid will be modern advanced sensor measurement technology, network technology, communication

计算机专业毕业设计说明书外文翻译(中英对照)

Talking about security loopholes Richard S. Kraus reference to the core network security business objective is to protect the sustainability of the system and data security, This two of the main threats come from the worm outbreaks, hacking attacks, denial of service attacks, Trojan horse. Worms, hacker attacks problems and loopholes closely linked to, if there is major security loopholes have emerged, the entire Internet will be faced with a major challenge. While traditional Trojan and little security loopholes, but recently many Trojan are clever use of the IE loophole let you browse the website at unknowingly were on the move. Security loopholes in the definition of a lot, I have here is a popular saying: can be used to stem the "thought" can not do, and are safety-related deficiencies. This shortcoming can be a matter of design, code realization of the problem. Different perspective of security loo phole s In the classification of a specific procedure is safe from the many loopholes in classification. 1. Classification from the user groups: ● Public loopholes in the software category. If the loopholes in Windows, IE loophole, and so on. ● specialized software loophole. If Oracle loopholes, Apach e,

外文翻译

Journal of Industrial Textiles https://www.wendangku.net/doc/b517583107.html,/ Optimization of Parameters for the Production of Needlepunched Nonwoven Geotextiles Amit Rawal, Subhash Anand and Tahir Shah 2008 37: 341Journal of Industrial Textiles DOI: 10.1177/1528083707081594 The online version of this article can be found at: https://www.wendangku.net/doc/b517583107.html,/content/37/4/341 Published by: https://www.wendangku.net/doc/b517583107.html, can be found at:Journal of Industrial TextilesAdditional services and information for https://www.wendangku.net/doc/b517583107.html,/cgi/alertsEmail Alerts: https://www.wendangku.net/doc/b517583107.html,/subscriptionsSubscriptions: https://www.wendangku.net/doc/b517583107.html,/journalsReprints.navReprints: https://www.wendangku.net/doc/b517583107.html,/journalsPermissions.navPermissions: https://www.wendangku.net/doc/b517583107.html,/content/37/4/341.refs.htmlCitations: - Mar 28, 2008Version of Record >>

计算机网络-外文文献-外文翻译-英文文献-新技术的计算机网络

New technique of the computer network Abstract The 21 century is an ages of the information economy, being the computer network technique of representative techniques this ages, will be at very fast speed develop soon in continuously creatively, and will go deep into the people's work, life and study. Therefore, control this technique and then seem to be more to deliver the importance. Now I mainly introduce the new technique of a few networks in actuality live of application. keywords Internet Network System Digital Certificates Grid Storage 1. Foreword Internet turns 36, still a work in progress Thirty-six years after computer scientists at UCLA linked two bulky computers using a 15-foot gray cable, testing a new way for exchanging data over networks, what would ultimately become the Internet remains a work in progress. University researchers are experimenting with ways to increase its capacity and speed. Programmers are trying to imbue Web pages with intelligence. And work is underway to re-engineer the network to reduce Spam (junk mail) and security troubles. All the while threats loom: Critics warn that commercial, legal and political pressures could hinder the types of innovations that made the Internet what it is today. Stephen Crocker and Vinton Cerf were among the graduate students who joined UCLA professor Len Klein rock in an engineering lab on Sept. 2, 1969, as bits of meaningless test data flowed silently between the two computers. By January, three other "nodes" joined the fledgling network.

外文翻译computerprogram英文.doc

Computer Program 1 Introduction Computer Program, set of instructions that directs a computer to perform someprocessing function or combination of functions. For the instructions to be carried out, a computer must execute a program, that is, the computer reads the program, and then follow the steps encoded in the program in a precise order until completion. A program can be executed many different times, with each execution yielding a potentially different result depending upon the options and data that the user gives the computer. Programs fall into two major classes: application programs and operating systems. An application program is one that carries out somefunction directly for a user, such as word processing or game-playing. An operating system is a program that manages the computer and the various resources and devices connected to it, such as RAM,hard drives, monitors, keyboards, printers, and modems,so that they maybe used by other programs. Examples of operating systems are DOS, Windows 95, OS\2, and UNIX. 2 Program Development Software designers create new programs by using special applications programs, often called utility programs or development programs. A programmer uses another type of program called a text editor to write the new program in a special notation called a programming language. With the text editor, the programmer creates a text file, which is an ordered list of instructions, also called the program source file. The individual instructions that make up the program source file are called source code. At this point, a special applications program translates the source code into machine language, or object code— a format that the operating system

计算机专业外文文献翻译6

外文文献翻译（译成中文2000字左右）： As research laboratories become more automated,new problems are arising for laboratory managers.Rarely does a laboratory purchase all of its automation from a single equipment vendor. As a result,managers are forced to spend money training their users on numerous different software packages while purchasing support contracts for each. This suggests a problem of scalability. In the ideal world,managers could use the same software package to control systems of any size; from single instruments such as pipettors or readers to large robotic systems with up to hundreds of instruments. If such a software package existed, managers would only have to train users on one platform and would be able to source software support from a single vendor. If automation software is written to be scalable, it must also be flexible. Having a platform that can control systems of any size is far less valuable if the end user cannot control every device type they need to use. Similarly, if the software cannot connect to the customer’s Laboratory Information Management System (LIMS) database,it is of limited usefulness. The ideal automation software platform must therefore have an open architecture to provide such connectivity. Two strong reasons to automate a laboratory are increased throughput and improved robustness. It does not make sense to purchase high-speed automation if the controlling software does not maximize throughput of the system. The ideal automation software, therefore, would make use of redundant devices in the system to increase throughput. For example, let us assume that a plate-reading step is the slowest task in a given method. It would make that if the system operator connected another identical reader into the system, the controller software should be able to use both readers, cutting the total throughput time of the reading step in half. While resource pooling provides a clear throughput advantage, it can also be used to make the system more robust. For example, if one of the two readers were to experience some sort of error, the controlling software should be smart enough to route all samples to the working reader without taking the entire system offline. Now that one embodiment of an ideal automation control platform has been described let us see how the use of C++ helps achieving this ideal possible. DISCUSSION C++: An Object-Oriented Language Developed in 1983 by BjarneStroustrup of Bell Labs,C++ helped propel the concept of object-oriented programming into the mainstream.The term ‘‘object-oriented programming language’’ is a familiar phrase that has been in use for decades. But what does it mean? And why is it relevant for automation software? Essentially, a language that is object-oriented provides three important programming mechanisms:

外文翻译中文版(完整版)

毕业论文外文文献翻译 毕业设计（论文）题目关于企业内部环境绩效审计的研究翻译题目最高审计机关的环境审计活动 学院会计学院 专业会计学 姓名张军芳 班级09020615 学号09027927 指导教师何瑞雄

最高审计机关的环境审计活动 1最高审计机关越来越多的活跃在环境审计领域。特别是1993-1996年期间，工作组已检测到环境审计活动坚定的数量增长。首先，越来越多的最高审计机关已经活跃在这个领域。其次是积极的最高审计机关，甚至变得更加活跃：他们分配较大部分的审计资源给这类工作，同时出版更多环保审计报告。表1显示了平均数字。然而，这里是机构间差异较大。例如，环境报告的数量变化，每个审计机关从1到36份报告不等。 1996-1999年期间，结果是不那么容易诠释。第一，活跃在环境审计领域的最高审计机关数量并没有太大变化。“活性基团”的组成没有保持相同的：一些最高审计机关进入，而其他最高审计机关离开了团队。环境审计花费的时间量略有增加。二，但是，审计报告数量略有下降，1996年和1999年之间。这些数字可能反映了从量到质的转变。这个信号解释了在过去三年从规律性审计到绩效审计的转变（1994-1996年，20％的规律性审计和44％绩效审计;1997-1999：16％规律性审计和绩效审计54％）。在一般情况下，绩效审计需要更多的资源。我们必须认识到审计的范围可能急剧变化。在将来，再将来开发一些其他方式去测算人们工作量而不是计算通过花费的时间和发表的报告会是很有趣的。 在2000年，有62个响应了最高审计机关并向工作组提供了更详细的关于他们自1997年以来公布的工作信息。在1997-1999年，这62个最高审计机关公布的560个环境审计报告。当然，这些报告反映了一个庞大的身躯，可用于其他机构的经验。环境审计报告的参考书目可在网站上的最高审计机关国际组织的工作组看到。这里这个信息是用来给最高审计机关的审计工作的内容更多一些洞察。 自1997年以来，少数环境审计是规律性审计（560篇报告中有87篇，占16％）。大多数审计绩效审计（560篇报告中有304篇，占54％），或组合的规律性和绩效审计（560篇报告中有169篇，占30％）。如前文所述，绩效审计是一个广泛的概念。在实践中，绩效审计往往集中于环保计划的实施（560篇报告中有264篇，占47％），符合国家环保法律，法规的，由政府部门，部委和/或其他机构的任务给访问（560篇报告中有212篇，占38％）。此外，审计经常被列入政府的环境管理系统（560篇报告中有156篇，占28％）。下面的元素得到了关注审计报告：影响或影响现有的国家环境计划非环保项目对环境的影响;环境政策;由政府遵守国际义务和承诺的10％至20％。许多绩效审计包括以上提到的要素之一。 1本文译自：S. Van Leeuwen.(2004).’’Developments in Environmental Auditing by Supreme Audit Institutions’’ Environmental Management Vol. 33, No. 2, pp. 163–1721

变电站_外文翻译_外文文献_英文文献_变电站的综合概述

英文翻译 A comprehensive overview of substations Along with the economic development and the modern industry developments of quick rising, the design of the power supply system become more and more completely and system. Because the quickly increase electricity of factories, it also increases seriously to the dependable index of the economic condition, power supply in quantity. Therefore they need the higher and more perfect request to the power supply. Whether Design reasonable, not only affect directly the base investment and circulate the expenses with have the metal depletion in colour metal, but also will reflect the dependable in power supply and the safe in many facts. In a word, it is close with the economic performance and the safety of the people. The substation is an importance part of the electric power system, it is consisted of the electric appliances equipments and the Transmission and the Distribution. It obtains the electric power from the electric power system, through its function of transformation and assign, transport and safety. Then transport the power to every place with safe, dependable, and economical. As an important part of power’s transport and control, the transformer substation must change the mode of the traditional design and control, then can adapt to the modern electric power system, the development of modern industry and the of trend of the society life. Electric power industry is one of the foundations of national industry and national economic development to industry, it is a coal, oil, natural gas, hydropower, nuclear power, wind power and other energy conversion into electrical energy of the secondary energy industry, it for the other departments of the national economy fast and stable development of the provision of adequate power, and its level of development is a reflection of the country's economic development an important indicator of the level. As the power in the industry and the importance of the national economy, electricity transmission and distribution of electric energy used in these areas is an indispensable component.。Therefore, power transmission and distribution is critical. Substation is to enable superior power plant power plants or power after adjustments to the lower load of books is an important part of power transmission. Operation of its functions, the capacity of a direct impact on the size of the lower load power, thereby affecting the industrial production and power consumption.Substation system if a link failure, the system will protect the part of action. May result in power outages and so on, to the production and living a great disadvantage. Therefore, the substation in the electric power system for the protection of electricity reliability,