Making an https://www.wendangku.net/doc/4115632735.html, Web Site Accessible
Scott Mitchell
May 2004
Summary: Take advantage of inheritance in the .NET Framework to extend https://www.wendangku.net/doc/4115632735.html, classes to make them generate https://www.wendangku.net/doc/4115632735.html, code that is fully accessible to people with disabilities. (13 printed pages) Introduction
While the majority of online users are able to browse Web sites using Web browsers with the typical browser settings, users with disabilities commonly use alternative means to access online information. For example, a blind user might use a text-only browser that converts the text into Braille, or reads the text aloud using a screen reader. A person with reduced vision might still use a browser like Microsoft® Internet Explorer, but with a screen magnifier, or with the browser configured to use extra large font sizes. Motor disabilities might preclude a user from using the mouse or keyboard as an input device.
Since people with disabilities typically surf the Web using special devices or non-standard browser configurations, a Web site's overall design and HTML markup greatly impacts the disabled person's user experience. For example, specifying font sizes using absolute measurements—like 10pt—displays the font in that absolute size, and not relative to the text size the user has configured in his browser. Sites that have a Flash or Shockwave interface, and do not provide an alternate, text representation, effectively cut off users with Braille devices or text-to-speech synthesizers. A Web site is said to be accessible if it is designed to transition gracefully to alternate devices.
At this point, you might be thinking, "Why should I bother ensuring my Web site is accessible?" There are two good reasons I can think of:
1.It's Good Business – According to the U.S. Census 2000, 49.7 million Americans have a disability; a June 2000 poll by Harris Interactive shows that 43% of disabled Americans are regular online users, and that users with disabilities spend almost twice as much time online than users without disabilities. Put the results of these two surveys together and you'll find that there are more than 21 million Americans with disabilities who are regularly online. By not taking the time to make your Web site accessible, you are cutting off 21 million potential visitors.
2. It's a Mandate for Government Agencies – In 1998 the United State government passed Section 508 of the Rehabilitation Act, requiring Federal agencies to make their electronic information accessible to individuals with disabilities. This law provides accessibility guidelines for software applications and Web applications, as well as telecommunication products and video products. Not only are Federal agencies required to implement accessibility guidelines, but also private companies that are contracted to work for the Federal government. (A number of countries outside the U.S. also have similar accessibility requirements for government agencies.) Therefore, creating accessible Web applications is required if you work for the government or for a company that provides services to the government.
In this article we will discuss what steps you can take to ensure that your Microsoft? https://www.wendangku.net/doc/4115632735.html, Web site is accessible. We'll take a brief look at the official accessibility guidelines available today, and then focus in on the accessibility guidelines used by the United States government. The article wraps up with a look at how to use inheritance to turn non-accessible https://www.wendangku.net/doc/4115632735.html, Web controls into ones that meet accessibility guidelines.
The WAI, WCAG, and Section 508
There are a number of steps that can be taken to make a Web site more accessible. But what, exactly, are these steps, and how many of them does one site need to employ in order to be considered accessible? The answers to these questions differ based on who you ask, and what level of accessibility they need to provide. An intranet site for a Fortune 500 company would likely require a higher degree of accessibility than an intranet site for a company with only 25 employees.
The WC3's Say on Accessibility
To help formalize this discussion, in 1999 the WC3 officially founded the Web Accessibility Initiative (WAI), a group tasked with improving Web site usability for people with disabilities. The WAI's first act was to publish the Web Content Accessibility Guidelines, or WCAG. The WCAG provides a list of 14 guidelines for accessible Web site design. The guidelines themselves do not spell out actions to take to make a Web site more accessible. Rather, they are high-level statements that provide comment on how to ensure accessibility. For example, guideline 1 is "Provide equivalent alternatives to auditory and visual content." Accompanying each guideline is a set of checkpoints. The checkpoints spell out actions that can be taken to ensure that the accessibility guideline is met. Each checkpoint is given one of the following priority values:
? Priority 1 – a Web developer must satisfy this checkpoint, otherwise one or more groups of users will not be able to access the content.
? Priority 2 – a Web developer should satisfy this checkpoint, otherwise one or more groups of users will find it difficult to access the content.
? Priority 3 –a Web developer may address this checkpoint, otherwise one or more groups of users might have difficulty when accessing the content.
In addition to listing the 14 guidelines and their associated, prioritized checkpoints, the WCAG also
provides a three-level classification scale for Web site accessibility. Sites that implement all Priority 1 checkpoints are rated at conformance level A. Those that implement all Priority 1 and Priority 2 checkpoints are rated Double-A, while those that implement all of the checkpoints are rated Triple-A. The WCAG gives a good set of actions to perform to ensure varying levels of accessibility.
Although a thorough discussion of the WCAG is beyond the scope of this article, listed below are the 14 high-level guidelines of the WCAG. The checkpoints for each guideline, and their associated priority, can be found at the official Web Content Accessibility Guidelines 1.0 specification.
15. Provide equivalent alternatives to auditory and visual content
16. Don't rely on color alone
17. Use markup and style sheets and do so properly
18. Clarify natural language use
19. Create tables that transform gracefully
20. Ensure that pages featuring new technologies transform gracefully
21. Ensure user control of time-sensitive content changes
22. Ensure direct accessibility of embedded user interfaces
23. Design for device-independence
24. Use interim solutions
25. Use W3C technologies and guidelines
26. Provide context and orientation information
27. Provide clear navigation mechanisms
28. Ensure that documents are clear and simple
Microsoft's Accessible https://www.wendangku.net/doc/4115632735.html, Web Controls for https://www.wendangku.net/doc/4115632735.html, 1.x.Many of the WCAG checkpoints and Section 508 rules dictate specific HTML markup that should be used to make a Web site more accessible. For example, checkpoint 5.1 in the WCAG (a Priority 1 checkpoint) and rule (g) in Section 508 requires that
elements properly identify row and column headers. That is, the
element must be used to identify data cells, whereas
must be used to identify headers.When building https://www.wendangku.net/doc/4115632735.html, Web sites, developers rarely have to worry about generating HTML markup. Rather, Web controls are used that emit the proper markup. Unfortunately, many of the https://www.wendangku.net/doc/4115632735.html, Web controls emit markup that violates the accessibility rules outlined by the WCAG and Section 508. Since all Web controls are, fundamentally, classes in the Microsoft® .NET Framework, their functionality can be extended in a number of ways to conform to accessibility guidelines.A prime example of enhancing an existing https://www.wendangku.net/doc/4115632735.html, Web control to meet accessibility guidelines can be seen with the DataGrid Web control. The DataGrid Web control that ships with the .NET Framework does not conform to rule (g) in Section 508 / checkpoint 5.1 in the WCAG. That is, the headers are rendered using
elements instead of
. (To see what I mean, check out this live demo, and do a View/Source in your browser. You'll see that the header row uses
s rather than
s.) However, in June 2003 Microsoft released
an https://www.wendangku.net/doc/4115632735.html, Hotfix Rollup Package that, among other things, includes an improved version of the DataGrid, one that conforms to rule (g) in Section 508.
Note The https://www.wendangku.net/doc/4115632735.html, Hotfix Rollup Package provides other accessibility-related enhancements. For example, it adds an optional AssociatedControlID property to the Label Web control to specify the ID of the Web control the Label is associated with. If this property is provided, the Label is rendered as a
Creating An Adaptive, Accessible DataGrid Web Control
The Web controls provided in the June 2003 Hotfix bring the https://www.wendangku.net/doc/4115632735.html, Web controls up to Section 508 standards. Even with the Hotfix, however, there are still a number of WCAG Priority 1 checkpoints not being met. Fortunately you can easily extend the functionality of existing Web controls to conform to the accessibility guidelines required by your company. This is possible thanks to the power of inheritance. Specifically, we can take a Web control that does not conform to the accessibility standards, and create an extended Web control that does conform to the standards. By using inheritance, we only have to change or add the functionality to make the control conforming to the standards, and do not have to rewrite the base functionality.
WCAG Checkpoint 6.3 reads: "Ensure that pages are usable when scripts, applets, or other programmatic objects are turned off or not supported. If this is not possible, provide equivalent information on an alternative accessible page. For example, ensure that links that trigger scripts work when scripts are turned off or not supported (for example, do not use "javascript:" as the link target)." However, the LinkButton Web control is rendered as a hyperlink with a javascript: link target (...). The problem is that browsers that don't support JavaScript won't be able to postback the Web page by clicking on the LinkButton. This renders sortable DataGrids unsortable in browsers that don't support JavaScript since the column headers are rendered as LinkButtons.
The remainder of this article looks at building a set of adaptive custom DataGrid columns that will display a Button Web control in the header of a sortable DataGrid if it is visited by a browser that doesn't support JavaScript. The Button Web control works for browsers that do not support JavaScript since it renders a tag rather than a hyperlink with a javascript: link target.
Note Section 508 does not require that links not use the javascript: link target. Section 508's sole comment on client-side script can be found in rule (l), which reads: "pages utilize scripting languages to display content, or to create interface elements, the information provided by the script shall be identified with functional text that can be read by assistive technology." What this rule requires is that if content is generated by script, or if a page's behavior is modified via script, that a
Making DataGridColumn Adaptive
The DataGrid Web control is comprised of a number of columns, which are classes that derive from the System.Web.UI.WebControls.DataGridColumn class. https://www.wendangku.net/doc/4115632735.html, ships with five built-in DataGrid column types:
1. BoundColumn
2. ButtonColumn
3. EditCommandColumn
4. HyperLinkColumn
5. TemplateColumn
The base class, DataGridColumn, provides the properties and methods inherent to all DataGrid column types. These include properties like HeaderText, SortExpression, Visible, and others. The DataGridColumn class has two methods that play an important role in creating a DataGrid: ?Initialize() –initializes the DataGridColumn. Called once per column during the DataGrid's databinding process.
?InitializeCell(cell, index, itemType) – called for each cell that is created during for each column during the DataGrid's databinding process. Cell is a TableCell object representing the actual HTML
cell for the cell being initializes; index is the row index of the cell being initialized; itemType is value from the ListItemType enumeration, specifying what type of cell is being added (Item, AlternatingItem, Header, Footer, EditItem, and so on.
The DataGridColumn class is responsible for rendering the header and footer for the column. The derived classes –BoundColumn, ButtonColumn, EditCommandColumn, etc. –are responsible for rendering the DataGrid items.
Note For more information on creating custom DataGrid columns, check out Marcie Robillard's article Creating Custom Columns for the https://www.wendangku.net/doc/4115632735.html, DataGrid.To have our DataGrid adaptively render the header based on whether or not the user's browser supports JavaScript, we need to create a custom DataGrid class that is derived from DataGridColumn. This custom DataGrid column class, named AccessibleDataGridColumn, will need to override the DataGridColumn class's InitializeCell() method, checking to see if the DataGrid is configured for sorting and being visited by a browser that doesn't support JavaScript. If these two conditions are true, then AccessibleDataGridColumn will render a Button in the header as opposed to a LinkButton. The code for this class is shown below:
The overridden InitializeCell() method checks to see if sorting is enabled, if the current browser does not support client-side JavaScript, if the current item being initialized is a header, and if the rendering is not being performed in Microsoft® Visual Studio® .NET's designer. If this check passes, then another check is performed to determine if the column has a HeaderImageUrl value specified. If it does, it renders an ImageButton, setting its AlternateText to the column's HeaderText. If there is no HeaderImageUrl specified, a Button is created and added to the cell.
Note Notice that the check to see whether or not a browser supports JavaScript simply looks up Request.Browser.JavaScript property. This property is set based on the User-Agent string sent by the
browser to the Web server. The adaptive DataGrid will render Buttons in the header for a sortable DataGrid when someone visits with a browser that is known not to support JavaScript, such as Netscape 1.0, or Lynx. If someone visits with Microsoft® Internet Explorer 6.0 it will render the default LinkButtons, even if the visitor has manually turned off JavaScript support.
Using the Accessible DataGrid Column Classes in an https://www.wendangku.net/doc/4115632735.html, Web Page
This article's download includes two Microsoft® Visual Studio® .NET 2003 projects (both Visual Basic .NET projects): the first is a class library that contains the custom DataGrid column classes; the second is an https://www.wendangku.net/doc/4115632735.html, Web application that you can use to test out the adaptive, accessible DataGrid column classes.
To use these custom DataGrid column classes in an https://www.wendangku.net/doc/4115632735.html, Web project you need to first add the compiled assembly of the custom DataGrid column classes to the https://www.wendangku.net/doc/4115632735.html, Web project's /bin folder. (If you are using Visual Studio .NET, the simplest way to do this is to add the assembly to the References folder in the Solution Explorer.) Next, you need to add a @References directive at the top of the https://www.wendangku.net/doc/4115632735.html, Web pages that will utilize these DataGrid columns like so:
Finally, to use the columns, add a DataGrid to the https://www.wendangku.net/doc/4115632735.html, Web page and set the AutoGenerateColumns property to False. In the HTML portion, add the following syntax:
...
That's all there is to it! Figure 3 shows a screenshot of the HTML portion of an https://www.wendangku.net/doc/4115632735.html, Web page that uses the AccessibleBoundColumn and AccessibleButtonColumn DataGrid column classes. Figure 4 shows a screenshot of the design view of that same page.
Figure 3. Using the AccessibleBoundColumn
Figure 4. AccessibleBoundColumn in the designer
Notice that in the Visual Studio .NET Designer the DataGrid with the custom, accessible columns appears just like normal. Too, if you view the page through a browser that supports JavaScript (as Figure 5 shows), the DataGrid will be rendered as it normally is, with LinkButtons in the column headers and ButtonColumn. However, if you visit the page with a browser that doesn't support JavaScript, such as Netscape 1.0, the ButtonColumn and column headers will be rendered as Buttons (see Figure 6).
Figure 5. AccessibleBoundColumn in up-level browser
Figure 6. AccessibleBoundColumn in older browser
Accessibility in https://www.wendangku.net/doc/4115632735.html, Whidbey
The https://www.wendangku.net/doc/4115632735.html, server controls that ship in the next version of https://www.wendangku.net/doc/4115632735.html,, codenamed Whidbey, will automatically generate Section 508-compliant markup by default. Furthermore, these server controls will emit WCAG-compliant markup as well. To top it off, Microsoft® Visual Studio® .NET 2005 will ship with an add-in to automatically check HTML markup for Section 508 and WCAG-compliance. For more information on these exciting additions, check out XHTML and Accessibility in https://www.wendangku.net/doc/4115632735.html, Whidbey, a blog post from Scott Guthrie, co-founder of the https://www.wendangku.net/doc/4115632735.html, team at Microsoft.
For more information about Web site accessibility, be sure to check out Microsoft's Accessibility home page. There's also a Section 508 page as well, with resources on how various Microsoft products meet Section 508 standards.
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当大多数的网络用户使用带有典型设置的浏览器访问网页时，那些没有能力的用户一般利用可选的方法获得网上的信息。例如，盲人可能使用一种可以将文字转换成盲文的文本浏览器，或者用一个屏幕阅读器大声地读出来。一个视力衰竭的人可能仍然在使用诸如Microsoft® Internet Explorer的浏览器，但是要辅助于屏幕放大器，或者设定特别大的显示字体。运动能力丧失的人可能就不能使用鼠标和键盘作为一种输入设备。
Inventory management Inventory Control On the so-called "inventory control", many people will interpret it as a "storage management", which is actually a big distortion. The traditional narrow view, mainly for warehouse inventory control of materials for inventory, data processing, storage, distribution, etc., through the implementation of anti-corrosion, temperature and humidity control means, to make the custody of the physical inventory to maintain optimum purposes. This is just a form of inventory control, or can be defined as the physical inventory control. How, then, from a broad perspective to understand inventory control? Inventory control should be related to the company's financial and operational objectives, in particular operating cash flow by optimizing the entire demand and supply chain management processes (DSCM), a reasonable set of ERP control strategy, and supported by appropriate information processing tools, tools to achieved in ensuring the timely delivery of the premise, as far as possible to reduce inventory levels, reducing inventory and obsolescence, the risk of devaluation. In this sense, the physical inventory control to achieve financial goals is just a means to control the entire inventory or just a necessary part; from the perspective of organizational functions, physical inventory control, warehouse management is mainly the responsibility of The broad inventory control is the demand and supply chain management, and the whole company's responsibility. Why until now many people's understanding of inventory control, limited physical inventory control? The following two reasons can not be ignored: First, our enterprises do not attach importance to inventory control. Especially those who benefit relatively good business, as long as there is money on the few people to consider the problem of inventory turnover. Inventory control is simply interpreted as warehouse management, unless the time to spend money, it may have been to see the inventory problem, and see the results are often very simple procurement to buy more, or did not do warehouse departments . Second, ERP misleading. Invoicing software is simple audacity to call it ERP, companies on their so-called ERP can reduce the number of inventory, inventory control, seems to rely on their small software can get. Even as SAP, BAAN ERP world, the field of
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。
JSP的技术发展历史 作者：Kathy Sierra and Bert Bates 来源：Servlet&JSP Java Server Pages(JSP)是一种基于web的脚本编程技术，类似于网景公司的服务器端Java脚本语言—— server-side JavaScript(SSJS)和微软的Active Server Pages(ASP)。与SSJS和ASP相比，JSP具有更好的可扩展性，并且它不专属于任何一家厂商或某一特定的Web服务器。尽管JSP规范是由Sun 公司制定的，但任何厂商都可以在自己的系统上实现JSP。 在Sun正式发布JSP之后，这种新的Web应用开发技术很快引起了人们的关注。JSP为创建高度动态的Web应用提供了一个独特的开发环境。按照Sun的说法，JSP能够适应市场上包括Apache WebServer、IIS4.0在内的85%的服务器产品。 本文将介绍JSP相关的知识，以及JavaBean的相关内容，当然都是比较粗略的介绍其中的基本内容，仅仅起到抛砖引玉的作用，如果读者需要更详细的信息，请参考相应的JSP的书籍。 1.1 概述 JSP(Java Server Pages)是由Sun Microsystems公司倡导、许多公司参与一起建立的一种动态网页技术标准，其在动态网页的建设中有其强大而特别的功能。JSP与Microsoft的ASP技术非常相似。两者都提供在HTML代码中混合某种程序代码、由语言引擎解释执行程序代码的能力。下面我们简单的对它进行介绍。 JSP页面最终会转换成servlet。因而，从根本上，JSP页面能够执行的任何任务都可以用servlet 来完成。然而，这种底层的等同性并不意味着servlet和JSP页面对于所有的情况都等同适用。问题不在于技术的能力，而是二者在便利性、生产率和可维护性上的不同。毕竟，在特定平台上能够用Java 编程语言完成的事情，同样可以用汇编语言来完成，但是选择哪种语言依旧十分重要。 和单独使用servlet相比，JSP提供下述好处： JSP中HTML的编写与维护更为简单。JSP中可以使用常规的HTML：没有额外的反斜杠，没有额外的双引号，也没有暗含的Java语法。 能够使用标准的网站开发工具。即使是那些对JSP一无所知的HTML工具，我们也可以使用，因为它们会忽略JSP标签。 可以对开发团队进行划分。Java程序员可以致力于动态代码。Web开发人员可以将经理集中在表示层上。对于大型的项目，这种划分极为重要。依据开发团队的大小，及项目的复杂程度，可以对静态HTML和动态内容进行弱分离和强分离。 此处的讨论并不是说人们应该放弃使用servlet而仅仅使用JSP。事实上，几乎所有的项目都会同时用到这两种技术。在某些项目中，更适宜选用servlet，而针对项目中的某些请求，我们可能会在MVC构架下组合使用这两项技术。我们总是希望用适当的工具完成相对应的工作，仅仅是servlet并不一定能够胜任所有工作。 1.2 JSP的由来 Sun公司的JSP技术，使Web页面开发人员可以使用HTML或者XML标识来设计和格式化最终
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.
C++ [1] Gordon Hogenson. C++/Cli The Visual C++ Language For .Net [M]. Wiley India Pvt. Ltd., 2007. [2] Motor Industry Software Reliability Association. MISRA-C: 2004: guidelines for the use of the C language in critical systems.[M]. MIRA, 2008. [3] Jeff Cogswell, John Paul Mueller. C++ All-In-One Desk Reference For Dummies [M]. Wiley publishing.Inc 2009. [4] Stephen R. Davis. C++ for Dummies [M]. wiley publishing.Inc 2008. [5] Harvey Dietel, Paul Deitel. C: How to Program [M]. Pearson Education,Inc 2010. [6] Bruce Eckel. Thinking in C++[M]. Prentice Hall, 2000. [7] Herbert Schildt. C++: a beginner's guide Beginner's Guides[M]. McGraw-Hill Professional, 2003. [8] Mark Lee. C++ Programming for the Absolute Beginner For the Absolute Beginner[M]. Course Technology, 2009. MIS参考文献 [9] Kenneth C. Laudon, Jane P. Laudon . Management Information Systems: Managing the Digital Firm[M]. Publisher Prentice Hall, 2007. [10] Raymond McLeod, George P. Schell. Management information systems[M]. Pearson/Prentice Hall, 2007. [11] James A. O'Brien, George M. Marakas. Management Information Systems[M]. McGraw-Hill/Irwin, 2008.
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,
毕业设计_英语专业论文外文翻译
1. Introduction America is one of the countries that speak English. Because of the special North American culture, developing history and the social environment, American English has formed its certain unique forms and the meaning. Then it turned into American English that has the special features of the United States. American English which sometimes also called United English or U.S English is the form of the English language that used widely in the United States .As the rapid development of American economy, and its steady position and strong power in the world, American English has become more and more widely used. As in 2005, more than two-thirds of English native speakers use various forms of American English. The philologists of the United States had divided the English of the United States into four major types: “America n creating”; “Old words given the new meaning”; “Words that eliminated by English”;“The phonetic foreign phrases and the languages that are not from the English immigrates”[1]. Compared to the other languages, American English is much simple on word spelling, usage and grammar, and it is one of the reasons that American English is so popular in the world. The thesis analyzes the differences between American English and British English. With the main part, it deals with the development of American English, its peculiarities compared to that of British English, its causes and tendency. 2. Analyses the Differences As we English learners, when we learning English in our junior or senior school, we already came across some words that have different spellings, different pronunciations or different expressions, which can be represented by following contrasted words: spellings in "color" vs. "colour"; pronunciations in "sec-re-ta-ry" vs. "sec-re-try";
毕业论文外文文献
毕业论文外文文献 Photography Pen Film director and critic Alexander Astruc's comments in today, wrote a famous: "Following a variety of other arts, especially painting, novel, film is rapidly becoming a tool to express ideas. It swept the market, a mall next to the theater's entertainment products. It is a well preserved image of the times methods. Now is gradually becoming a language, that is, the artist can use it to express themselves through a means of thinking, no matter how abstract this idea, or that it is also used as a kind of artists like prose or fiction a form to express their themes. So, I put this new era for film today called "photo pen" era, that era of writing, the use of the camera …… "Silent film attempts to use symbolic links to all the concept and meaning of the expression. We know, Lenovo exist in the image itself, naturally present in the film development process, there is the role of performance in each posture and expression, present in every word of in; also present in the camera movement, this movement linked to a piece of things, to link people and things …… "Obviously, that is, screenwriter making his own films. Or even say that there is no longer what the movie writer. Because, in such films, the playwright and director, there is nothing between significant
博物馆 外文翻译 外文文献 英文文献
第一篇： 航空博物馆与航空展示公园 巴特罗米耶杰·基谢列夫斯基 飞翔的概念、场所的精神、老机场的建筑---克拉科夫新航空博物馆理性地吸取了这些元素，并将它们整合到一座建筑当中。Rakowice-Czyzyny机场之前的旧飞机修理库为新建筑的平面和高度设定了模数比例。在此基本形态上进一步发展，如同裁切和折叠一架纸飞机，生成了一座巨大的建筑。其三角形机翼是由混凝土制成，却如同风动螺旋桨一样轻盈。这个机翼宽大通透，向各个方向开敞。它们的形态与组织都是依据内部功能来设计的。机翼部分为3个不平衡的平面，使内外景观在不断变化中形成空间的延续性，并且联系了建筑内的视觉焦点和室外的展览区。 新航空展示公园的设计连接了博物馆的8栋建筑和户外展览区，并与历史体验建立联系。从前的视觉轴线与通道得到尊重，旧的道路得到了完善，朝向飞机场和跑道的空间被限定出来。每栋建筑展示了一个主题或是一段飞行史。建筑周围伸展出巨大的平台，为特殊主题的室外展览提供了空间。博物馆容纳了超过150架飞机、引擎、飞行复制品、成套的技术档案和历史图片。这里的特色收藏是飞机起源开始的各种飞行器，如Jatho1903、Grade1909、莱特兄弟1909年的飞机模型和1911年的鸽式单翼机。 The first passage: Museum for aviation and aviation exhibition park Bartiomiej Kislelewski The idea of flying, the spirit of place, the structure of the historic airfield – the new Museum of Aviation in Krakow takes up these references intellectually and synthesizes them into a building. The old hangars of the former airport Rakowice Czyzyny set the modular scale for the footprint and the height of the new building. Developed from this basic shape, as if cut out and folded like a paper airplane, a large structure has been generated, with triangular wings made of concrete and yet as light as a wind-vane propeller. The wings are generously glazed and open in all directions. Their form and arrangement depend on the interior uses. In the floor plans of the wings, the three offset
java毕业论文外文文献翻译
Advantages of Managed Code Microsoft intermediate language shares with Java byte code the idea that it is a low-level language witha simple syntax , which can be very quickly translated intonative machine code. Having this well-defined universal syntax for code has significant advantages. Platform independence First, it means that the same file containing byte code instructions can be placed on any platform; atruntime the final stage of compilation can then be easily accomplished so that the code will run on thatparticular platform. In other words, by compiling to IL we obtain platform independence for .NET, inmuch the same way as compiling to Java byte code gives Java platform independence. Performance improvement IL is actually a bit more ambitious than Java bytecode. IL is always Just-In-Time compiled (known as JIT), whereas Java byte code was ofteninterpreted. One of the disadvantages of Java was that, on execution, the process of translating from Javabyte code to native executable resulted in a loss of performance. Instead of compiling the entire application in one go (which could lead to a slow start-up time), the JITcompiler simply compiles each portion of code as it is called (just-in-time). When code has been compiled.once, the resultant native executable is stored until the application exits, so that it does not need to berecompiled the next time that portion of code is run. Microsoft argues that this process is more efficientthan compiling the entire application code at the start, because of the likelihood that large portions of anyapplication code will not actually be executed in any given run. Using the JIT compiler, such code willnever be compiled.
