第一篇:畢業設計外文翻譯
外文原文
Overview of JSp Technology
Benefits of JSp
JSp pages are translated into servlets.So, fundamentally, any task JSp pages can perform could also be accomplished by servlets.However, this underlying equivalence does not mean that servlets and JSp pages are equally appropriate in all scenarios.The issue is not the power of the technology, it is the convenience, productivity, and maintainability of one or the other.After all, anything you can do on a particular computer platform in the Java programming language you could also do in assembly language.But it still matters which you choose.JSp provides the following benefits over servlets alone:
?It is easier to write and maintain the HTML.Your static code is ordinary HTML: no extra backslashes, no double quotes, and no lurking Java syntax.?You can use standard Web-site development tools.Even HTML tools that know nothing about JSp can be used because they simply ignore the JSp tags.?You can divide up your development team.The Java programmers can work on the dynamic code.The Web developers can concentrate on the presentation layer.On large projects, this division is very important.Depending on the size of your team and the complexity of your project, you can enforce a weaker or stronger separation between the static HTML and the dynamic content.Now, this discussion is not to say that you should stop using servlets and use only JSp instead.By no means.Almost all projects will use both.For some requests in your project, you will use servlets.For others, you will use JSp.For still others, you will combine them with the MVC architecture.You want the appropriate tool for the job, and servlets, by themselves, do not complete your toolkit.Advantages of JSp Over Competing Technologies
A number of years ago, Marty was invited to attend a small 20-person industry roundtable discussion on software technology.Sitting in the seat next to Marty was James Gosling, inventor of the Java programming language.Sitting several seats away was a high-level manager from a very large software company in Redmond, Washington.During the discussion, the moderator brought up the subject of Jini, which at that time was a new Java technology.The moderator asked the manager what he thought of it, and the manager responded that it was too early to tell, but that it seemed to be an excellent idea.He went on to say that they would keep an eye on it, and if it seemed to be catching on, they would follow his company's usual “embrace and extend” strategy.At this point, Gosling lightheartedly interjected “You mean disgrace and distend.”
Now, the grievance that Gosling was airing was that he felt that this company would take technology from other companies and suborn it for their own purposes.But guess what? The shoe is on the other foot here.The Java community did not invent the idea of designing pages as a mixture of static HTML and dynamic code marked with special tags.For example, ColdFusion did it years earlier.Even ASp(a product from the very software company of the aforementioned manager)popularized this approach before JSp came along and decided to jump on the bandwagon.In fact, JSp not only adopted the general idea, it even used many of the same special tags as ASp did.So, the question becomes: why use JSp instead of one of these other technologies? Our first response is that we are not arguing that everyone should.Several of those other technologies are quite good and are reasonable options in some situations.In other situations, however, JSp is clearly better.Here are a few of the reasons.Versus.NET and Active Server pages(ASp)
.NET is well-designed technology from Microsoft.ASp.NET is the part that directly competes with servlets and JSp.The advantages of JSp are twofold.First, JSp is portable to multiple operating systems and Web servers;you aren't locked into deploying on Windows and IIS.Although the core.NET platform runs on a few non-Windows platforms, the ASp part does not.You cannot expect to deploy serious ASp.NET applications on multiple servers and operating systems.For some applications, this difference does not matter.For others, it matters greatly.Second, for some applications the choice of the underlying language matters greatly.For example, although.NET's C# language is very well designed and is similar to Java, fewer programmers are familiar with either the core C# syntax or the many auxiliary libraries.In addition, many developers still use the original version of ASp.With this version, JSp has a clear advantage for the dynamic code.With JSp, the dynamic part is written in Java, not VBScript or another ASp-specific language, so JSp is more powerful and better suited to complex applications that require reusable components.You could make the same argument when comparing JSp to the previous version of ColdFusion;with JSp you can use Java for the “real code” and are not tied to a particular server product.However, the current release of ColdFusion is within the context of a J2EE server, allowing developers to easily mix ColdFusion and servlet/JSp code.Versus pHp
pHp(a recursive acronym for “pHp: Hypertext preprocessor”)is a free, open-source, HTML-embedded scripting language that is somewhat similar to both ASp and JSp.One advantage of JSp is that the dynamic part is written in Java, which already has an extensive ApI for networking, database access, distributed objects, and the like, whereas pHp requires learning an entirely new, less widely used language.A second advantage is that JSp is much more widely supported by tool and server vendors than is pHp.Versus pure Servlets
JSp doesn't provide any capabilities that couldn't, in principle, be accomplished with servlets.In fact, JSp documents are automatically translated into servlets behind the scenes.But it is more convenient to write(and to modify!)regular HTML than to use a zillion println statements to generate the HTML.plus, by separating the presentation from the content, you can put different people on different tasks: your Web page design experts can build the HTML by using familiar tools and either leave places for your servlet programmers to insert the dynamic content or invoke the dynamic content indirectly by means of XML tags.Does this mean that you can just learn JSp and forget about servlets? Absolutely not!JSp developers need to know servlets for four reasons:
1.JSp pages get translated into servlets.You can't understand how JSp works without understanding servlets.2.JSp consists of static HTML, special-purpose JSp tags, and Java code.What kind of Java code? Servlet code!You can't write that code if you don't understand servlet programming.3.Some tasks are better accomplished by servlets than by JSp.JSp is good at generating pages that consist of large sections of fairly well structured HTML or other character data.Servlets are better for generating binary data, building pages with highly variable structure, and performing tasks(such as redirection)that involve little or no output.4.Some tasks are better accomplished by a combination of servlets and JSp than by either servlets or JSp alone.Versus JavaScript
JavaScript, which is completely distinct from the Java programming language, is normally used to dynamically generate HTML on the client, building parts of the Web page as the browser loads the document.This is a useful capability and does not normally overlap with the capabilities of JSp(which runs only on the server).JSp pages still include SCRIpT tags for JavaScript, just as normal HTML pages do.In fact, JSp can even be used to dynamically generate the JavaScript that will be sent to the client.So, JavaScript is not a competing technology;it is a complementary one.It is also possible to use JavaScript on the server, most notably on Sun ONE(formerly iplanet), IIS, and BroadVision servers.However, Java is more powerful, flexible, reliable, and portable.Versus WebMacro or Velocity
JSp is by no means perfect.Many people have pointed out features that could be improved.This is a good thing, and one of the advantages of JSp is that the specification is controlled by a community that draws from many different companies.So, the technology can incorporate improvements in successive releases.However, some groups have developed alternative Java-based technologies to try to address these deficiencies.This, in our judgment, is a mistake.Using a third-party tool like Apache Struts that augments JSp and servlet technology is a good idea when that tool adds sufficient benefit to compensate for the additional complexity.But using a nonstandard tool that tries to replace JSp is a bad idea.When choosing a technology, you need to weigh many factors: standardization, portability, integration, industry support, and technical features.The arguments for JSp alternatives have focused almost exclusively on the technical features part.But portability, standardization, and integration are also very important.For example, the servlet and JSp specifications define a standard directory structure for Web applications and provide standard files(.war files)for deploying Web applications.All JSp-compatible servers must support these standards.Filters can be set up to apply to any number of servlets or JSp pages, but not to nonstandard resources.The same goes for Web application security settings.Besides, the tremendous industry support for JSp and servlet technology results in improvements that mitigate many of the criticisms of JSp.For example, the JSp Standard Tag Library and the JSp 2.0 expression language address two of the most well-founded criticisms: the lack of good iteration constructs and the difficulty of accessing dynamic results without using either explicit Java code or verbose jsp:useBean elements.10.4 Misconceptions About JSp
Forgetting JSp Is Server-Side Technology
Here are some typical questions Marty has received(most of them repeatedly).?Our server is running JDK 1.4.So, how do I put a Swing component in a JSp page?
?How do I put an image into a JSp page? I do not know the proper Java I/O commands to read image files.?Since Tomcat does not support JavaScript, how do I make images that are highlighted when the user moves the mouse over them?
?Our clients use older browsers that do not understand JSp.What should we do?
?When our clients use “View Source” in a browser, how can I prevent them from seeing the JSp tags?
All of these questions are based upon the assumption that browsers know something about the server-side process.But they do not.Thus:
?For putting applets with Swing components into Web pages, what matters is the browser's Java version—the server's version is irrelevant.If the browser supports the Java 2 platform, you use the normal AppLET(or Java plug-in)tag and would do so even if you were using non-Java technology on the server.?You do not need Java I/O to read image files;you just put the image in the directory for Web resources(i.e., two levels up from WEB-INF/classes)and output a normal IMG tag.?You create images that change under the mouse by using client-side JavaScript, referenced with the SCRIpT tag;this does not change just because the server is using JSp.?Browsers do not “support” JSp at all—they merely see the output of the JSp page.So, make sure your JSp outputs HTML compatible with the browser, just as you would do with static HTML pages.?And, of course you need not do anything to prevent clients from seeing JSp tags;those tags are processed on the server and are not part of the output that is sent to the client.Confusing Translation Time with Request Time
A JSp page is converted into a servlet.The servlet is compiled, loaded into the server's memory, initialized, and executed.But which step happens when? To answer that question, remember two points:
?The JSp page is translated into a servlet and compiled only the first time it is accessed after having been modified.?Loading into memory, initialization, and execution follow the normal rules for servlets.Table 1 gives some common scenarios and tells whether or not each step occurs in that scenario.The most frequently misunderstood entries are highlighted.When referring to the table, note that servlets resulting from JSp pages use the _jspService method(called for both GET and pOST requests), not doGet or dopost.Also, for initialization, they use the jspInit method, not the init method.Table 1.JSp Operations in Various Scenarios
JSp page translated into servletServlet compiledServlet loaded into server's memoryjspInit called_jspService called
page first written
Request 1YesYesYesYesYes
Request 2NoNoNoNoYes
Server restarted
Request 3NoNoYesYesYes
Request 4NoNoNoNoYes
page modified
Request 5YesYesYesYesYes
Request 6NoNoNoNoYes
中文翻譯
JSp技術概述
一、JSp的好處
JSp頁面最終會轉換成servler。因而,從根本上,JSp頁面能夠執行的任何任務都可以用servler來完成。然而,這種底層的等同性并不意味著servler和JSp頁面對于所有的情況都等同適用。問題不在于技術的能力,而是二者在便利性、生產率和可維護性上的不同。畢竟,在特定平臺上能夠用Java編程語言完成的事情,同樣可以用匯編語言來完成,但是選擇哪種語言依舊十分重要。
和單獨使用servler相比,JSp提供下述好處:
?JSp中HTML的編寫與維護更為簡單。JSp中可以使用常規的HTML:沒有額外的反斜杠,沒有額外的雙引號,也沒有暗含的Java語法。
?能夠使用標準的網站開發工具。即使對那些對JSp一無所知的HTML工具,我們也可以使用,因為它們會忽略JSp標簽(JSp tags)。
?可以對開發團隊進行劃分。Java程序員可以致力于動態代碼。Web開發人員可以將經理集中在表示層(presentation layer)上。對于大型的項目,這種劃分極為重要。依據開發團隊的大小,及項目的復雜程度,可以對靜態HTML和動態內容進行弱分離(weaker separation)和強分離(stronger separation)。
在此,這個討論并不是讓您停止使用servlets,只使用JSp。幾乎所有的項目都會同時用到這兩種技術。針對項目中的某些請求,您可能會在MVC構架下組合使用這兩項技術。我們總是希望用適當的工具完成相對應的工作,僅僅是servlet并不能填滿您的工具箱。
二、JSp相對于競爭技術的優勢
許多年前,Marty受到邀請,參加一個有關軟件技術的小型(20個人)研討會.做在Marty旁邊的人是James Gosling---Java編程語言的發明者。隔幾個位置,是來自華盛頓一家大型軟件公司的高級經理。在討論過程中,研討會的主席提出了Jini的議題,這在當時是一項新的Java技術.主席向該經理詢問他的想法.他繼續說,他們會持續關注這項技術,如果這項技術變得流行起來,他們會遵循公司的“接受并擴充(embrace and extend)”的策略.此時, Gosling隨意地插話說“你的意思其實就是不接受且不擴充(disgrace and distend)。”
在此, Gosling的抱怨顯示出,他感到這個公司會從其他公司那里拿走技術,用于他們自己的目的.但你猜這次怎么樣?這次鞋子穿在了另一只腳上。Java社團沒有發明這一思想----將頁面設計成由靜態HTML和用特殊標簽標記的動態代碼混合組成.。ColdFusion多年前就已經這樣做了。甚至ASp(來自于前述經理所在公司的一項產品)都在JSp出現之前推廣了這種方式。實際上,JSp不只采用了這種通用概念,它甚至使用許多和ASp相同的特殊標簽。
因此,問題變成:為什么使用JSp,而不使用其他技術呢?我們的第一反應是我們不是在爭論所有的人應該做什么。其他這些技術中,有一些也很不錯,在某些情況下也的確是合情合理的選擇.然而,在其他情形中,JSp明顯要更好一些。下面給出幾個理由。
與.NET和Active Server pages(ASp)相比
.NET是Microsoft精心設計的一項技術。ASp.NET是與servlets和JSp直接競爭的技術。JSp的優勢體現在兩個方面。
首先,JSp可以移植到多種操作系統和Web服務器,您不必僅僅局限于部署在Windows 和IIS上盡管核心.NET平臺可以在好幾種非Windows平臺上運行,但ASp這一部分不可以。您不能期望可以將重要的ASp.NET應用部署到多種服務器和操作系統。對于某些應用,這種差異沒有什么影響。但有些應用,這種差異卻非常重要。
其次,對于某些應用,底層語言的選擇至關重要。例如,盡管.NET的C#語言設計優良,且和Java類似,但熟悉核心C#語法和眾多工具庫的程序員很少。此外,許多開發者依舊使用最初版本的ASp。相對于這個版本,JSp在動態代碼方面擁有明顯的優勢。使用JSp,動態部分是用Java編寫的,而非VBScript過其他ASp專有的語言,因此JSp更為強勁,更適合于要求組件重用的復雜應用。
當將JSp與之前版本的ColdFusion對比時,您可能會得到相同的結論。應用JSp,您可以使用Java編寫“真正的代碼”,不必依賴于特定的服務器產品。然而,當前版本的ColdFusion滿足J2EE服務器的環境,允許開發者容易的混合使用ColdFusion和Servlet/JSp代碼。
與pHp相比
pHp(“pHp:Hypertext preprocessor”的遞歸字母縮寫詞)是免費的、開放源代碼的、HTML嵌入其中的腳本語言,與ASp和JSp都有某種程度的類似。JSp的一項優勢是動態部分用Java編寫,而Java已經在聯網、數據庫訪問、分布式對象等方面擁有廣泛的ApI,而pHp需要學習全新的、應用相對廣泛的語言。JSp的第二項優勢是,和pHp相比,JSp擁有極為廣泛的工具和服務器提供商的支持。
與純Servlet相比
原則上,JSp并沒有提供Servlet不能完成的功能。實際上,JSp文檔在后臺被自動轉換成Servlet。但是編寫(和修改)常規的HTML,要比無數println語句生成HTML要方便得多。另外,通過將表示與內容分離,可以為不同的人分配不同的任務:網頁設計人員使用熟悉的工具構建HTML,要么為Servlet程序員留出空間插入動態內容,要么通過XML標簽間接調用動態內容。
這是否表示您只可以學習JSp,將Servlet丟到一邊呢?當然不是!由于以下4種原因,JSp開發人員需要了解Servlet:
(1)JSp頁面會轉換成Servlet。不了解Servlet就無法知道JSp如何工作。
(2)JSp由靜態HTML、專用的JSp標簽和Java代碼組成。哪種類型的Java代碼呢?當然是Servlet代碼!如果不了解Servlet編程,那么就無法編寫這種代碼。
(3)一些任務用Servlet完成比用JSp來完成要好。JSp擅長生成由大量組織有序的結構化HTML或其他字符數據組成的頁面。Servlet擅長生成二進制數據,構建結構多樣的頁面,以及執行輸出很少或者沒有輸出的任務(比如重定向)。
(4)有些任務更適合于組合使用Servlet和JSp來完成,而非單獨使用Servlet或JSp。
與JavaScript相比
JavaScript和Java編程語言完全是兩碼事,前者一般用于在客戶端動態生成HTML,在瀏覽器載入文檔時構建網頁的部分內容。這是一項有用的功能,一般與JSp的功能(只在服務器端運行)并不發生重疊。和常規HTML頁面一樣,JSp頁面依舊可以包括用于JavaScript的SCRIpT標簽。實際上,JSp甚至能夠用來動態生成發送到客戶端的JavaScript。因此,JavaScript不是一項競爭技術,它是一項補充技術。
JavaScript也可以用在服務器端,最因人注意的是SUN ONE(以前的iplanet)、IIS和BroadVision服務器。然而,Java更為強大靈活、可靠且可移植。
與WebMacro和Velocity相比
JSp決非完美。許多人都曾指出過JSp中能夠改進的功能。這是一件好事,JSp的優勢之一是該規范由許多不同公司組成的社團控制。因此,在后續版本中,這項技術能夠得到協調的改進。
但是,一些組織已經開發出了基于Java的替代技術,試圖彌補這些不足。據我們的判斷,這樣做是錯誤的。使用擴充JSp和Servlet技術的第三方工具,如Apache Structs,是一種很好的思路,只要該工具帶來的好處能夠補償工具帶來的額外復雜性。但是,試圖使用非標準的工具代替JSp則不理想。在選擇一項技術時,需要權衡許多方面的因素:標準化、可移植性、集成性、行業支持和技術特性。對于JSp替代技術的爭論幾乎只是集中在技術特性上,而可移植性、標準化和集成性也十分重要。例如,Servlet和JSp規范為Web應用定義了一個標準的目錄結構,并提供用于部署Web應用的標準文件(.war文件)。所有JSp兼容的服務器必須支持這些標準。我們可以建立過濾器作用到任意樹木的Servlet和JSp頁面上,但不能用于非標準資源。Web應用安全設置也同樣如此。
此外,業界對JSp和Servlet技術的巨大支持使得這兩項技術都有了巨大的進步,從而減輕了對JSp的許多批評。例如,JSp標準標簽庫和JSp 2.0表達式語言解決了兩種最廣泛的批評:缺乏良好的迭代結構;不使用顯式的Java代碼或冗長的jsp:useBean元素難以訪問動態結果。
三、對JSp的誤解
忘記JSp技術是服務器端技術
下面是Marty收到的一些典型問題(大部分問題不止一次的出現)。
?我們的服務器正在運行JDK1.4。我如何將Swing組件用到JSp頁面中呢?
?我如何將圖像放到JSp頁面中?我不知道讀取圖像文件應該使用哪些Java I/O命令。
?Tomcat不支持JavaScript,當用戶在圖像上移動鼠標時,我如何使圖像突出顯示呢?
?我們的客戶使用不理解JSp的舊瀏覽器。我應該怎么做?
?當我們的客戶在瀏覽器中使用“View Source”(查看源代碼)時,如何阻止他們看到JSp標簽?
所有這些問題都基于瀏覽器對服務器端的過程在有所了解的假定之上。但事實上瀏覽器并不了解服務器端的過程。因此:
?如果要將使用Swing組件的applet放到網頁中,重要的是瀏覽器的Java版本,和服務器的Java版本無關。如果瀏覽器支持Java 2平臺,您可以使用正常的AppLET(或Java插件)標簽,即使在服務器上使用了非Java技術也須如此。
?您不需要Java I/O來讀取圖像文件,您只需將圖像放在存儲Web資源的目錄中(即WEB-INF/classes向上兩級的目錄),并輸出一個正常的IMG標簽。
?您應該用SCRIpT標簽,使用客戶端JavaScript創建在鼠標下會更改的圖像,這不會由于服務器使用JSp而改變。
?瀏覽器根本不“支持”JSp----它們看到的只是JSp頁面的輸出。因此,如同對待靜態HTML頁面一樣,只需確保JSp輸出的HTML與瀏覽器兼容。
?當然,您不需要采取什么措施來阻止客戶看到JSp標簽,這些標簽在服務器上進行處理,發送給客戶的輸出中并不出現。
混淆轉換期間和請求期間
JSp頁面需要轉換成servlet。Servlet在編譯后,載入到服務器的內容中,初始化并執行。但是每一步發生在什么時候呢?要回答這個問題,要記住以下兩點:
?JSp頁面僅在修改后第一次被訪問時,才會被轉換成servlet并進行編譯;
?載入到內存中、初始化和執行遵循servlet的一般規則。
表1列出一些常見的情形,講述在該種情況下每一步是否發生。最常被誤解的項已經突出標示出來。在參考該表時,要注意,由JSp頁面生成的servlet使用_jspService方法(GET和pOST請求都調用該函數),不是doGet或dopost方法。同樣,對于初始化,它們使用jspInit方法,而非init方法。
表1 各種情況下的JSp操作
將JSp 頁面轉換成servlet編譯Servlet 將Servlet 載入到服務器內存中調用jspInit 調用_jspService
頁面初次創建
請求 1有有有有有
請求 2無無無無有
服務器重啟后
請求3無無有有有
請求 4無無無無有
頁面修改后
請求 5有有有有有
請求 6無無無無有
第二篇:畢業設計冷凝器外文翻譯
吉林化工學院本科畢業設計(論文)外文翻譯
氨制冷系統的節能設計,改造和蒸發式冷凝器的控制
阿卜杜勒穆罕默德和凱利,工業評估中心,代頓大學
摘要
氨制冷系統通常提供了許多節能商機,因為他們的大動力消耗,運行時間長的和動態的操作。氨制冷系統的能源使用高度依賴于冷凝頭的壓力,而這是一個函數的蒸發式冷凝器容量和控制功能。本文研究系統能源利用中聚光能力和冷凝器的控制之間的關系。它首先開發方法來確定冷凝器的性能,然后以仿真模型模擬壓縮機和冷凝器風扇的能源利用。,它使用工程基本面和經驗兩個數據,準確地捕捉壓縮機,冷凝器和環境濕球溫度之間的協同效應。節約能源是三種情況:安裝在冷凝器風機變頻驅動器,采用濕球控制方法戰略和提高聚光性能。以說明氣候的影響,這些模擬是兩個不同的ASHRAE氣候區,邁阿密,佛羅里達州和執行明尼阿波利斯,明尼蘇達州,這是炎熱和寒冷的氣候分別。結果表明,提高表現不佳的冷凝器的性能是最經濟有效的節能測量。但是節約能源從冷凝器安裝變頻驅動器球迷和利用濕球的方法策略取決于環境氣候條件,與位置無關。接下來,內部收益率的計算方法來安裝額外的聚光能力超越在為相同的兩個ASHRAE氣候區新建筑應用的標準做法。結果表明,安裝兩次基線聚光能力,內部收益率超過20 %。綜上所述,本文提出的設計,改造的綜合方法在氨制冷系統蒸發式冷凝器的控制權。節約能源衍生通過使用這種方法可以顯著提高氨的能量效率制冷系統。
介紹
約7.5 %的總生產能耗用于食品加工行業,其中約21%的能量是電能(二零零六年環評)。在這些設備中,氨制冷系統是最大的能源消耗部分。制冷與冷卻工藝所用電量是食品加工行業(二零零六年EIA)的用電量的27%。制冷系統使用的能量是高度依賴于冷凝壓力,而這又是冷凝器容量和控制性能。因此,提高聚光能力和控制可導致顯著的節能效果。
本文首先確定使用的數據從實際的聚光性能制冷控制系統。然后是開發仿真模型來計算每年的能源使用所研究的壓縮機和冷凝器風扇。該仿真模型,用來計算節能三
吉林化工學院本科畢業設計(論文)外文翻譯
個節能措施(ECMS):在冷凝器風扇安裝變頻器,采用濕球的方法策略,提高聚光性能。以說明氣候的影響,這些仿真用于執行邁阿密,佛羅里達州和明尼蘇達州明尼阿波利斯,這是炎熱和寒冷的氣候分別。文章最后決定回報的安裝額外的容量超出標準規范的內部收益率在新的建筑應用。
系統說明
分析系統是一個兩階段的氨制冷系統具有兩個低壓側壓縮機和兩個高級壓縮機。所有的壓縮機是螺桿式與滑閥控制和熱虹吸油冷卻。一種蒸發式冷凝器以恒定的速度從系統散發熱量。對于本文的其余部分,術語系統將參考冷凝器風扇和壓縮機。從冷凝器泵的能源使用小,并且不評價了本文。關鍵系統參數,包括電動機電流,氨的壓力和溫度從制冷控制系統獲得。氨性數據的計算使用參考流體熱力學和輸運性質數據(NIST,2010)也被稱為REFPROP。圖中顯示了制冷系統的替補的示意圖。
圖1。電路圖制冷系統的pH值圖上
計算排熱到冷凝器
冷凝壓力是決定系統能源利用的一個關鍵變量。為了準確地計算冷凝壓力,冷凝器性能必須確定。在第一步驟中確定冷凝器性能是計算從壓縮機排出到總熱量冷凝器。在系統中的能量平衡顯示了總的熱拒絕了冷凝器是由低和高級壓縮機加兩個設置在制冷(QREF0)低和高級壓縮機兩者的壓縮或軸功率(WS)的熱量。
QCond.actual = Σ QrefLS +Σ QrefHS +Σ WSLS +Σ WsHS(1)
吉林化工學院本科畢業設計(論文)外文翻譯
所有的熱拒絕從低溫壓縮機減去熱虹吸拒絕的低級壓縮機油冷卻(TSOC,LS)將被轉移到高壓側制度。因此,由高溫壓縮機提供(TRprovided,HS)的制冷是:
ΣTRprovided,HS = Σ QrefLS +Σ QrefHS +Σ WLS
吉林化工學院本科畢業設計(論文)外文翻譯
量可以使用等式4和來自控制系統的百分之制冷容量,計算如下:
QREF = Qrrated ? %容量
(5)
壓縮熱由高溫級壓縮機(WsHS)生產
來自控制系統的數據而獲得的每個壓縮機的電機電流。至相關電機電流軸功率(WS),電機電流和輸入之間的關系權力必須得到發展。這種關系中,可以從點測量開發電機電流和輸入功率在整個壓縮機的工作范圍。通過使用的壓縮機(?m)的兩個銘牌效率和f(A),軸功率或等價每個壓縮機的壓縮熱量可以計算為:
WsHS = F(A)* ?m
(6)
熱虹吸油冷卻(TSOC)
考慮了兩階段的低溫循環在圖1中表示的氨制冷系統。在狀態1LS,氨進入壓縮機作為飽和蒸汽和離開壓縮機的過熱蒸汽在狀態2LS。路徑1LSmref.LS ?(h2a.LSh4.LS)(8)
通常,制造商報告的體積流量的空氣速率,標稱容量,并且熱抑制因子(HRF)。體積流量是用于使用計算的質量流率空氣的密度在標準條件。該HRF,這既是外部空氣濕球溫度計的功能溫度(TWB)和飽和冷凝溫度(Tcond),用于確定在額定容量冷凝器對于一個給定TWB和Tcond為(Manske,Reindl和2001年克萊因):
額定電容容量=標稱容量/ HRF(TWB,Tcond)(10)
等式9b和10可以適用于制造商的規格為蒸發冷凝器,以確定對于一個給定的濕球Tcond和效力之間的關系范圍。有效性被發現是線性相關的Tcond為: effM = E0
吉林化工學院本科畢業設計(論文)外文翻譯
由于蒸發式冷凝器的運行期間的實際容量已計算的,實際效果可以適合于在等式11的形式的線。測量效力與從所研究的系統Tcond數據被繪制時,無論是蒸發式冷凝器,風機和水泵是在圖3滿負荷生產。額定制造商從式(11)效果也繪制在同一張圖來比較的有效性上一個新的蒸發式冷凝器,以其中一個已經服役了幾年。圖3表示該蒸發式冷凝器性能已劣化隨著時間的推移。實際容量比制造商的額定容量少約40%。此信息可以被用作用于模擬程序的校準參數。例如,在圖3中,冷凝器容量為一個新的冷凝器將約為1.69倍,目前的實際能力。
圖3。實際和制造商有效性的蒸發式冷凝器
模擬年能源消耗
每年的能量使用的制冷系統的是壓縮機和冷凝器的總和風機能耗。冷凝壓力是必須正確地計算一個關鍵的變量正確模擬壓縮機和冷凝器風扇的能源使用。以下步驟概述一方法計算壓縮機功率,冷凝壓力和冷凝器風扇電源。
計算壓縮機輸入功率
一個給定的壓縮機在一定范圍抽吸的額定軸功率(bhprated)和冷凝溫度可以從制造商處獲得。此數據可以被嵌入到一個二階多項式方程的交互項來確定額定滿載
吉林化工學院本科畢業設計(論文)外文翻譯
軸功率在給定的吸氣和冷凝溫度(Manske 2000),如:
bhprated = P0 + P1 ? Tcond + P2 ? TSUC + P11 ? Tcond 2 + P22 ? TSUC 2 + P12 ? Tcond ? TSUC(12)
在該制冷系統中的壓縮機,像許多制冷系統中,在操作堿/修剪方式,表示過去壓縮機接通的每個階段是修剪壓縮機。式(4),它類似于公式12中,示出的滿負荷容量壓縮機吸入的函數和冷凝溫度下,該壓縮機運行。知道制冷負荷(參考負載)和堿的量被操作(Σ TRBase),則該部分的容量修剪壓縮機的壓縮機定階段(FCTrim)可以計算如下:
FCTrim =(參考負載6789
吉林化工學院本科畢業設計(論文)外文翻譯
紅色=壓縮機的能耗,藍=冷凝器風扇能源,綠色=節能,廣場=投資回報率,VFD =常數變速冷凝器風扇,所需時間約=利用濕球的方法和策略PERFOR =提高聚光性能。
在新建筑應用安裝額外的電容容量
冷凝器是因為結構支撐,管道和控制成本來安裝。因此,這是很少的成本效益來安裝額外的冷凝器為唯一目的能量效率。然而,在新建筑中安裝額外的冷凝器容量可以成本效益。近似的安裝成本與變頻驅動和濕球的做法冷凝器控制是指在公式23。增量成本(元)= 17 ·增容(MBH)+ 12,000(23)
在添加額外的冷凝器時收益率(IRR)內部收益率圖9顯示容量時,冷凝器的壽命是20年,能源漲價率是3 %。內部收益率計算用于安裝的50 %的額外容量,100%,150 %和200 %,比7000 MBH基線能力。在這兩個位置,內部收益率超過20%加倍聚光能力。因此,增加聚光能力似乎是一個非常有吸引力的選項的新建筑。
圖9。返回的安裝額外的電容容量內部收益率
紅色=增量成本,綠色=每年節約能源成本,回報廣場=內部收益率
小結與討論
本文開發了一種方法,利用數據來校準聚光性能制冷控制系統。此校準冷凝器性能的仿真中使用模型計算所研究的能源使用的系統。該仿真模型是然后用來計算節能三的ECM :在冷凝器風扇安裝變頻器,采用濕球的方法策略,提高聚光性能的兩個不同的ASHRAE氣候區。
重要的結果是:
1.制冷系統的總功耗是強烈依賴于冷凝器大小,性能和控制。
2.對于現有系統,提高了蒸發式冷凝器性能可能是最成本效益的節能措施。目視檢
吉林化工學院本科畢業設計(論文)外文翻譯
[4] Manske,K.A.,Reindl酒店,D.T.和克萊因2001年S.A.公司。在工業“蒸發式冷凝器的控制制冷系統制冷24 “國際雜志: 676-691。
[5]米切爾,J.W.博朗,J.E.,1998。“設計,分析和空間調節設備的控制和
系統”。威斯康星大學麥迪遜分校。
[6] 標準與技術,2010年全國學院,參考流體熱力學和運輸屬性數(REFPROP)8.0版 [7] 國家可再生能源實驗室,2005年,“用戶手冊TMY3s ”,http://rredc.nrel.gov/solar/old_data/nsrdb/1991-2005/tmy3/ [8] Stoecker,威爾伯特,1998年,工業制冷手冊。麥格勞13-
第三篇:畢業設計三相異步電動機外文翻譯
中文翻譯
異步電動機具有結構簡單、運行可靠、價格低、維護方便等一系列的優點,因此,異步電動機被廣泛應用在電力拖動系統中。尤其是隨著電力電子技術的發展和交流調速技術的日益成熟,使得異步電動機在調速性能方面大大提高。目前,異步電動機的電力拖動已被廣泛地應用在各個工業電氣自動化領域中。就三相異步電動機的機械特性出發,主要簡述電動機的啟動,制動、調速等技術問題。三相異步電動機的機械特性文
三相異步電動機的機械特性是指電動機的轉速n與電磁轉矩Tem之間的關系。由于轉速n與轉差率S有一定的對應關系,所以機械特性也常用Tem=f(s)的形式表示。三相異步電動機的電磁轉矩表達式有三種形式,即物理表達式、參數表達式和實用表達式。物理表達式反映了異步電動機電磁轉矩產生的物理本質,說明了電磁轉矩是由主磁通和轉子有功電流相互作用而產生的。參數表達式反映了電磁轉矩與電源參數及電動機參數之間的關系,利用該式可以方便地分析參數變化對電磁轉矩的影響和對各種人為特性的影響。實用表達式簡單、便于記憶,是工程計算中常采用的形式。
電動機的最大轉矩和啟動轉矩是反映電動機的過載能力和啟動性能的兩個重要指標,最大轉矩和啟動轉矩越大,則電動機的過載能力越強,啟動性能越好。
三相異步電動機的機械特性是一條非線性曲線,一般情況下,以最大轉矩(或臨界轉差率)為分界點,其線性段為穩定運行區,而非線性段為不穩定運行區。固有機械特性的線性段屬于硬特性,額定工作點的轉速略低于同步轉速。人為機械特性曲線的形狀可用參數表達式分析得出,分析時關鍵要抓住最大轉矩、臨界轉差率及啟動轉矩這三個量隨參數的變化規律。三相異步電動機的啟動
小容量的三相異步電動機可以采用直接啟動,容量較大的籠型電動機可以采用降壓啟動。降壓啟動分為定子串接電阻或電抗降壓啟動、Y-D降壓啟動和自耦變壓器降壓啟動。定子串電阻或電機降壓啟動時,啟動電流隨電壓一次方關系減小,而啟動轉矩隨電壓的平方關系減小,它適用于輕載啟動。Y-D降壓啟動只適用于正常運行時為三角形聯結的電動機,其啟動電流和啟動轉矩均降為直接啟動時的1/3,它也適用于輕載啟動。自耦變壓器降壓啟動時,啟動電流和啟動轉矩均降為直接啟動時的l/k2(k為自耦變壓器的變比),適合帶較大的負載啟動。
繞線轉子異步電動機可采用轉子串接電阻或頻敏變阻器啟動,其啟動轉矩大、啟動電流小,適用于中、大型異步電動機的重載啟動。
軟啟動器是一種集電機軟啟動、軟停車、輕載節能和多種保護功能于一體的新型電動機控制裝置,國外稱為Soft Starter。它的主要構成是串接于電源與被控電動機之間的三相反并聯晶閘管及其電子控制電路。運用串接于電源與被控電動機之間的軟啟動器,以不同的方法,控制其內部晶閘管的導通角,使電動機輸入電壓從零以預設函數關系逐漸上升,直至啟動結束,賦予電動機全電壓,即為軟啟動。在軟啟動過程中,電動機啟動轉矩逐漸增加,轉速也逐漸增加。軟啟動器實際上是個調壓器,用于電動機啟動時,輸出只改變電壓并沒有改變頻率。
三相異步電動機的調速
三相異步電動機的調速方法有變極調速、變頻調速和變轉差率調速。其中變轉差率調速包括繞線轉子異步電動機的轉子串接電阻調速、串級調速和降壓調速。
變極調速是通過改變定子繞組接線方式來改變電機極數,從而實現電機轉速的變化。變極調速為有級調速,變極調速時的定子繞組聯結方式有三種:Y-YY、順串Y-反串Y、D-YY。其中Y-YY聯結方式屬于恒轉矩調速方式,另外兩種屬于恒功率調速方式。變極調速時,應同時對調定子兩相接線,這樣才能保證調速后電動機的轉向不變。
變頻調速是現代交流調速技術的主要方向,它可實現無級調速,適用于恒轉矩和恒功率負載。
繞線轉子電動機的轉子串接電阻調速方法簡單,易于實現,但調速是有級的,不平滑,且低速時特性軟,轉速穩定性差,同時轉子銅損耗大,電動機的效率低。串級調速克服了轉子串接電阻調速的缺點,但設備要復雜得多。
異步電動機的降壓調速主要用于風機類負載的場合,或高轉差率的電動機上,同時應采用速度負反饋的閉環控制系統。
把電壓和頻率固定不變的工頻交流電變換為電壓或頻率可變的交流電的裝置稱作“變頻器”。為了產生可變的電壓和頻率,該設備首先要把電源的交流電變換為直流電(DC),這個過程叫整流。再把直流電(DC)變換為交流電(AC),這個過程叫逆變,把直流電變換為交流電的裝置叫逆變器(inverter)。對于逆變為頻率可調、電壓可調的逆變器我們稱為變頻器。變頻器輸出的波形是模擬正弦波,主要用在三相異步動機的調速,又叫變頻調速器。附錄 二
外文原文
Asynchronous motor has a simple structure, reliable operation, low price, convenient maintenance and a series of advantages, therefore, asynchronous motor is widely used in electric drive system.Especially with the development of power electronic technology and AC drive technology becomes more mature, greatly improve the speed performance makes the asynchronous motor.At present, electric drive asynchronous motor has been widely used in various industrial electrical automation.The mechanical properties of three-phase asynchronous motor starting, the main motor starting, braking, speed control technology.The mechanical properties of 1 three-phase asynchronous motor Mechanical characteristics of three-phase asynchronous motor is refers to the relationship between the speed of the motor electromagnetic torque of N and Tem.Due to the speed of N and slip S have a certain relationship, so the mechanical properties are also commonly used Tem = f(s)representation.Electromagnetic torque expression of three-phase asynchronous motor has three forms, namely physical expression, parameters and practical expression.Physical expressions reflect the physical nature of electromagnetic torque of asynchronous motor, the electromagnetic torque is generated by the main flux and rotor active current interaction.Parameter expression reflects the relationship between parameters of electromagnetic torque and power supply parameters and motor, the expression can be used to influence easily analyze the influence of parameter variation on the electromagnetic torque and all kinds of human characteristics.Practical expressions in a simple, easy to remember, is often used in engineering calculation in the form of.The maximum torque of motor and torque are two important indexes reflecting the overload capacity of the motor and starting performance, maximum torque and start torque motor overload capacity is bigger, stronger, better starting performance.The mechanical characteristic of three-phase asynchronous motor is a nonlinear curve, under normal circumstances, with the maximal torque(or critical slip)as a cutoff point, the linear segment for the stable operation region, while the nonlinear section is not stable operating region.Hard characteristic is linear segment inherent mechanical properties, the nominal operating point speed slightly lower than the synchronous speed.Shape parameters available expressions man-made mechanical characteristic curve analysis, analysis the key to grasp the maximum torque, starting torque variation of critical slip and the three with the parameters of.2 three-phase asynchronous motor starting Three-phase asynchronous motor with small capacity can be used to directly start, cage motor with large capacity can adopt step-down start.Step-down start into stator resistance or reactance step-down start, Y-D step-down start and autotransformer start.The stator resistance or motor step-down start, starting current voltage relations with a reduced, and the starting torque with the square of the voltage is reduced, it is suitable for the starting load.Only applicable to motor start to normal operation for the triangle connection Y-D buck, the starting current and starting torque is reduced to direct startup 1/3, which is also suitable for the starting load.Autotransformer start, starting current and starting torque is reduced to direct startup l/k2(k is the self coupling transformer), suitable for large load starting.The wound rotor asynchronous motor with rotor series resistance or frequency sensitive rheostat starting, the starting torque, small starting current, suitable for heavy load starting, large asynchronous motor.The soft starter is a novel control device for motor motor soft start, soft stop, light load energy saving and various protecting functions in one, called Soft Starter.The main structure is connected in series between the power supply and the controlled motor three-phase inverse parallel thyristor and its electronic control circuit.Through the series of soft starter is connected between the power supply and the controlled motor, in different ways, its internal control thyristor conduction angle, so that the motor input voltage from zero to a preset function gradually rise, until the end of the motor start, give full voltage, namely soft start.In the soft start-up process, starting torque motor speed increases gradually, gradually increasing.The soft starter is actually a regulator, for when the motor is started, the output voltage does not change the frequency change.3 speed of three-phase asynchronous motor Control method of the three-phase asynchronous motor with variable speed, variable speed and variable slip speed.The variable slip ratio control includes a rotor winding rotor asynchronous motor series resistance speed control, cascade control and blood pressure control.Variable speed is by changing the stator winding connection mode to change the pole number, so as to realize the change of motor speed.Variable speed is speed-regulation, variable stator winding connection speed of three kinds: Y-YY, Y-, D-YY and Y run.The Y-YY connection is constant torque speed control mode, another two species belong to the constant power control mode.Variable pole speed, should also be on the stator two-phase wiring, so that we can guarantee the speed regulation motor steering.Variable frequency speed control is the main direction of modern AC speed regulation technology, it can realize stepless speed regulation, suitable for constant torque and constant power load.Wound rotor rotor motor series resistance speed control method is simple, easy to implement, but speed is not smooth, level, and low speed characteristics of soft, speed stability is poor, and the rotor copper loss, motor efficiency is low.Cascade speed control to overcome the rotor series resistance speed disadvantage, but the equipment is much more complex.Step-down speed asynchronous motor for fan load, or high slip motor, closed-loop control system should be accompanied by negative feedback of speed.The industrial frequency alternating current voltage and frequency of fixed to variable voltage or frequency of the alternating current.
第四篇:交通畢業設計外文及翻譯
Synchro在交通控制與設計中的應用
在城市的較小的區域內,可以對區域內的所有交叉口進行控制;在城市較大的區域,可以對區域進行分區分級控制。分區的結果往往使面控制成為一個由幾條線控制組成的分級集中控制系統,這時,可認為各線控制是面控制中的一個單元;有時分區的結果是成為一個點,線,面控制的綜合性分級控制系統。現在對城市道路進行區域協調控制就是將其劃分為多級多個信號控制子區,對信號子區進行協調控制,優化管理控制信號子區,然后對整個道路進行區域協調控制,達到整個城市道路優化的目的。
把城市道路劃分為多個信號控制子區,也就是進行城市道路干線交叉口交通信號協調控制,把城市劃分為多個主路控制,再把主路上各個交叉口進行聯動控制,同時,對單個交叉口信號控制優化的同時需要考慮主路上下游各個交叉口的聯動控制。主路上的各個交叉口按照設計的信號配時方案進行運行,使車輛進入城市主干道交叉口時,不至經常遇到紅燈,稱為城市主干道交叉口信號協調控制,稱為“綠波”信號控制。
城市單點交叉口作為城市交通網絡中的重要組成部分,作為城市道路交通問題的關鍵點。對城市單點交叉口,評價標準的參考指標:交叉口的通行能力、進口道的飽和度、道路交叉口進口道停車延誤、交叉口進口道停車次數、進口道排隊長度和汽車的油耗等。交叉口定時信號控制配時方法在不斷的改進之中,國內外大部分學者認為從不同的評價指標出發,可以采用不同的種優化算法尋求其它更合理的配時方法。
平面交叉口按交通管制方式可以分為全無控制交叉口、主路優先控制交叉口、信號燈控制交叉口、環形交叉口等幾種類型。主路優先控制交叉口,是在次路上設停車讓行或減速讓行標志,指令次路車輛必須停車或減速讓主路車輛優先通行的一種交通管制方式。
交叉口是道路網中通行能力的“瓶頸”和交通事故的“黑點”。國內外城市中的交通堵塞主要發上在交叉口,造成車輛中斷,事故增多,延誤嚴重。如日本大城市中的機動車在城市中心的旅行時間約三分之一花在平面交叉口上。同時,交叉口也是交通事故的主要發生源。美國交通事故約有一半發生在交叉口;原聯邦德國道路上的交通事故約有百分之三十六發上在交叉口,城市中的交通事故約有百分之六十到百分之八十發生在交叉口及其附近。因此,交叉口這個交通事故“多發源”問題不能不引起人們的高度關注。怎樣對城市交叉口實施科學管理就是本
節要討論的問題。實施管制的方式取決于交叉口的幾何特征和交通狀況目的是為了保障交叉口的交通安全和和充分發揮交叉口的通行能力。本節主要以十字交叉口為主,討論全無控制交叉口和主路優先控制交叉口,同時簡要介紹現代環形交叉口的基本要點。
單個交叉口的控制策略會對其上游及下游道路交叉口的車流量產生很大的影響,上游和下游交叉口距離越近交通流量越大的情況下,影響會越大。交通信號“點控制”就是把單獨的交叉口拿出來進行單獨的分析,對其進行單獨的信號優化和道路控制策略,而不考慮該交叉口對其上下游交叉口的影響。城市道路交通信號區域協調控制的就是研究在一個城市道路子區內,對各個道路交叉口進行的信號周期時長、交叉口的綠信比以及路口間的相位差進行優化,以減小交叉口的停車延誤、提高城市路網的通行能力的交通區域信號協調控制方法。隨著城市道路區域信號協調控制理論的發展,研究者發現,可以把一個較大的城市的道路交通區域路網看成一個大的整體,對其進行交通信號協調控制及優化,由于道路路網及機動車流量的復雜性,但是對其優化結果對其通行能力的提高不是很理想。因此,從20世紀70年代,許多研究者開始嘗試將龐大、復雜繁瑣的道路路網按照一定的原則和方法模型進行劃分,劃分成若干個信號控制子區,然后再對信號控制子區域內進行協調信號控制,用以提高城市里整個道路路網的協調控制效果。
目前,城市道路交通擁堵問題己經成為全國乃至全世界都普遍關注問題。城市道路及交叉口作為城市交通道路的基本服務設施,主要包括道路交叉口與路段,其服務性能的良好運行直接影響到城市交通的正常運轉。
城市道路交叉口是道路系統的重要組成部分,城市道路通過交叉口這個節點把各條道路互相連接構成城市的道路路網,來協調交叉口各個進口方向上的車流量需要;同時在城市道路網絡中各種各樣的交通流(機動車,非機動車,行人)在此相互交叉通過、分流轉向,可見交叉口是城市道路網絡最為重要的位置。但交叉口也是交通堵塞和交通事故的多發地點。城市道路運輸機動車的效率、道路安全度、交叉口通行能力、道路的服務水平對環境和能源的影響基本上取決于城市道路交叉口的通行能力。
在對城市道路交叉口中控制和優化中最為常見的是信號控制,在信號控制中單點信號交叉口是城市道路控制與優化的基礎。對城市道路交叉口進行科學合理的信號控制與優化,是提高城市交叉口的交通安全和通行能力、減少交叉口停車
延誤的有效措施,可以緩解城市擁堵的交通問題。
對城市道路交叉口信號進行控制優化的方法模型進行說明,介紹了交通信號燈控制的基本方法,熟悉介紹交通信號管理軟件synchro的相關功能和仿真情況,以synchro為工具進行城市道路區域的協調控制,對城市道路區域協調控制模型進行介紹!以呼和浩特城市道路為例,通過對呼和浩特道路現狀交通的分析調查,運用交通管理軟件synchro進行仿真,通過對仿真結果的分析結合呼和浩特現在的道路狀況,得到現狀道路所存在的交通問題,通過對問題的分析,提出相應的優化方案,然后運用synchro對優化后的交通情況進行仿真,對比評價仿真結果,提出優化方案。對城市交通信號問題進行優化,挺高城市交通道路的通行能力!完善城市交通的基礎設施!
本論文通過對城市道路交叉口交通信號的控制的說明,介紹了交通信號燈控制的基本方法,引出了城市道路交通信號區域控制,通過對城市交通信號區域控制的介紹,提出了對城市道路交通信號區域進行分級控制優化的方法模型。
本論文通過對交通信號仿真優化軟件synchro6.0各個功能的介紹,軟件優化模型及各評價指標的計算方法與模型的相關介紹。基于呼和浩特市新城區,以新城區新華大街為主干道進行城市道路主干道交通信號控制與優化仿真。通過對新華大街與錫林郭勒北路,新華大街與迎賓北路,新華大街與呼倫貝爾北路各個交叉口交通信號配時方案,道路屬性,交通量等進行調查,通過對調查數據進行處理研究,運用交通信號控制仿真軟件synchro6.0進行交通現狀的仿真,然后再對新華大街主干道信號配時方案進行優化,對優化結果進行仿真,進行評價然后進行優化前后的仿真對比。說明道路主干道控制優化的優點。由于本次設計時間較短,加上本人在這方面的學習研究還有待提高,所以本論文只能簡單地介紹相關的設計方法和模型,對于更加復雜交錯的交叉口還有待進一步的學習和研究。
總體來說,Synchro系統對信號交叉口的配時方案及優化程序主要針對交叉口信號周期時長、相位方案和交叉口綠信比等進行總體綜合優化。該系統能充分考慮到該區域道路的各項性質(交叉口范圍內的公交站點、公共交通的影響,交叉口范圍內的路邊停車、自行車和行人等各種外在因素對交叉口通行能力和服務水平的影響,其適用能力強,是一種專業針對信號交叉口使用較為簡便的信號控制優化配時軟件。
道路交叉口停車計算與交叉口延誤的計算方法相同。在交叉口進口道產生停
車延誤的車輛數與排隊車輛數相同,如上圖中的Q。同時Synchro系統認為10s以內延誤的車輛沒有完全停車,對這些車輛,Synchro通過計算每個車輛每次在進口道延誤的時間,對延誤在10s以內的車輛按照定好的相應比例確定停車數。
由于新華大街各個交叉口相距很近,使得交叉口與交叉口之間的車容量較小,而且各個交叉口之間的信號燈周期時長不同,不能進行關聯管理,亦使得新華大街不能進行綠波交通控制。對各個交叉口信號周期進行優化后,可以顯著提高交叉口的服務水平,且可以對新華大街主干道進行聯動控制,大大的減小了新華大街主干道上的延誤
在這段時間里,我通過對交通信號管理與仿真軟件 synchro的不斷熟悉與運用,逐漸深入的了解到了交叉口交通信號對城市道路交通的重要性!交通信號對于緩解現在各個城市道路擁擠的重要性,在這段時間里,我通過對呼和浩特新城區新華大街主干道道路情況和各個交叉口的交通情況的調查與統計,發現可以運用交通信號管理軟件synchro對各個交叉口進行優化仿真,可以使新華大街主干道進行“線控制“,進而提高新華大街主干道各個交叉口的通行能力。
Synchro in traffic control and the design application
In city of smaller area, within the area can be controlled all the intersection;In the city of large region, can region partition of hierarchical control.The division of the results often make level control into one by the few line of control the grading of centralized control system, at this moment, you may think that makes the control is the surface control a unit;Sometimes the division of the results is to become a point, line, face the comprehensive control of hierarchical control system.Now on the city road for regional coordination control is dividing the multilevel more signal control branch area, the son of signal area for coordinated control, optimizing the management control signal branch area, and then to the road for regional coordination control to achieve the purpose of the whole city road optimization.The urban road is divided into more signal control branch area, also is the city road junction lines to the traffic signal coordination control, the city is divided into more massive control, and each intersection on running for linkage control, at the same time, to a single intersection signal control optimization and at the same time to consider all the linkage of the massive upstream and downstream intersection control.Each intersection running according to design signal timing formula for operation, make the vehicle into the city intersection, not often meet with red light, called city intersection signal coordination control, known as the ”green wave“ signal control.City single point as a city intersection traffic network in the important part of urban road traffic problems as the key point.City intersection of single point, evaluation standard reference index: crossing capacity, the import of saturation, the way the intersections, intersection delay import way parking import stops, import way way queue length and the car fuel consumption, etc.Timing signal intersection control timing method in continuous improvement in, most scholars think both at home and abroad from different evaluation index set out, can adopt different kinds of optimization algorithm for other, more reasonable timing method.According to the plane intersection traffic control way without control can be divided into the intersection, massive priority control signal intersection control, intersection, ring intersection of several types.Massive priority intersection control, is on the way in time set the right-of-way or slow down the right-of-way parking sign, instruction time road vehicles must stop or slow down to the right-of-way vehicles running a traffic control method.Intersection of road network traffic capacity is in the ”bottleneck“ and traffic accidents ”black spots“.The traffic jam main cities at home and abroad to the hair in the intersection, causing traffic disruption, more accidents, delay serious.Such as Japan cities in motor vehicle in the city center of about a third of the travel time spent on plane intersection.At the same time, the intersection of the traffic accident is the main sources.The United States about half the traffic accident happened in the intersection;The federal Germany on the road traffic accident about thirty-six percent to the hair in the intersection, city in the traffic accident happened about sixty percent to eighty percent in the intersection and its nearby.Therefore, the intersection traffic accident ”was“ not aroused people's concern.How to carry out the scientific management of city intersection of this section is to talk
about the problem.Implementation of the control mode depends on the geometrical characteristics of the intersection and traffic conditions the purpose is to ensure the intersection of traffic safety and and give full play to the crossing capacity.This section mainly intersections is given priority to, to discuss all to no control intersection and massive priority intersection control, and briefly introduced the basic points of modern ring intersection.The single intersection control strategy of the upstream and downstream will road intersection traffic produce very big effect, intersection upstream and downstream the closer the greater the traffic flow, the greater the effect will be.The traffic signal ”point control" is to separate out the intersection of the separate analysis, and carry on the single signal optimization and road control strategy, and don't consider the intersection of the upstream and downstream the influence of the intersection.The urban road traffic signal control is the study of the regional coordination in a city way way zone, to each road intersections of signal period of how long, how intersection green than and between the letter at phase difference is optimized, to minimize the intersection delay parking, improve the urban road network capacity traffic signal control method coordination area.Along with the urban road area signal coordination control the development of the theory, the researchers found that, can be to a larger city road traffic area network as a great whole, the traffic signal coordination control and optimization, as a result of road network and the complexity of the flow of motor vehicles, but for the optimization results to the travel of the ability is not very ideal.Therefore, since the 1970 s, many researchers began to try to be huge, complex tedious road network according to certain principles and methods model division, divided into several signal control branch area, and then again to signal control subdomain coordinate signal control, to improve the way of city road network coordination control effect.At present, the urban road traffic congestion problem has been become the attention and to the world.City road and intersection traffic as a city of basic services, mainly including road intersection and sections, the service performance in good operating directly affect the normal operation of city traffic.City road crossing the road system is an important component of the urban road through the intersection nodes to the various factors of city road connect each other of road network, to coordinate each intersection on the direction of imported cars need;At the same time in the city road network all kinds of traffic flow(motor vehicle, the motor vehicle, pedestrians)in the cross each other through the shunt turned, visible intersection of city road network is the most important position.But the intersection is traffic and traffic accidents of the multiple sites.City road transport vehicle efficiency, road safety degree, intersection traffic capacity, the service level of the road to the environment and the influence of the energy basically depends on the urban road crossing capacity.In the urban road intersections control and optimization of the most common is the signal of control, signal control of a single point signal intersection control and optimization of city road is based.City road intersection of scientific reasonable signal control and optimization, is to improve the city traffic safety and the intersection traffic capacity, reduce the effective measures to stop intersection delay, can ease congestion
第五篇:建筑學本科畢業設計外文翻譯
本科畢業設計外文翻譯 題目: 德黑蘭城市發展
學 院: 專 業: 學 號: 學生姓名: 指導教師:
城市建設學院 建筑學
日 期: 二零一一年六月
First Chapter:Development of the city of Tehran
Ali Madanipour 武漢科技大學本科畢業設計外文翻譯
Tehran :the making of a metropolis,First Chapter:Development of the city of Tehran,Ali Madanipour,ISBN:0471957798,Press: New York John Wiley,1998,page five to page eleven。
第一章:德黑蘭市的發展
阿里.馬丹妮普爾
德黑蘭:一個大都市的建造,第一章:德黑蘭市的發展,阿里.馬丹妮普爾,書號:0471957798,紐約John Wiley出版社,1998,第五頁到第十一頁。
德黑蘭市的發展
全市已長成了一定的規模性和復雜性,以這樣的程度,空間管理需要另外的手段來處理城市組織和不斷發展的復雜性,并為城市總體規劃做準備。
第二次世界大戰后,在盟軍占領國家的期間,有一個時期的民主化,在冷戰時開始的政治緊張局勢之后,它們互相斗爭對石油的控制權。這個時期已經結束于1953年,結果 武漢科技大學本科畢業設計外文翻譯
是由政變產生了伊朗王,那個后來擔任了25年的行政君主的人。隨著高出生率和農村向城市遷移,德黑蘭和其他大城市增長加劇甚至比以前更快地。到1956年,德黑蘭的人口上升到150萬,到了1966至300萬,1976至450萬,其規模也從1934年46平方公里到1976年的250平方公里。
從石油行業的收入增長創造的盈余資源,需要流通和經濟的吸收。50年代中期,特別是在工業化的驅動下德黑蘭許多大城市有了新工作。20世紀60年代的土地改革釋放了大量來自農業的農村人口,這是不能吸收的指數人口增長。這種新的勞動力被吸引到城市:到新的產業,到似乎始終蓬勃發展建筑界,去服務不斷增長公共部門和官僚機構。德黑蘭的角色是國家的行政,經濟,文化中心,它堅定而鞏固地通往外面的世界。德黑蘭戰后的城市擴張,是在管制、私營部門的推動,投機性的發展下進行的。房屋一直供不應求,并有大量可用的富余勞動力和資本,因此在德黑蘭建筑行業蓬勃發展,土地和財產的價格不斷上漲。這個城市成長為一個在某種意義上道路對外脫節的,城鎮和鄉村一體化的,郊區不斷增長的新的定居點。這加強了社會的孤立性,破壞了郊區的花園和綠地,并使城市管理者的感到無能為力。1962年一位副市長在德黑蘭表示:“建筑物和居民點已經滿足人們所想要的無論何處何種樣子”,創造了一個“事實上城鎮相互連接的方式不當”的城市(Nafisi, 1964,第426頁)。有許多事情迫切需要做,但市政府并沒有法律上或經濟上有能力處理這進程。
1966年市政法第一次規定了城規最高委員會的法律體制和土地利用規劃公司的綜合計劃。還有他一系列法律,以支持德黑蘭市的新的法律和體制安排,使住房和其他管理工作在城市中發展起來。最重要的一步是策劃的德黑蘭綜合計劃于1968年被批準。它是由一個伊朗規劃師Fereydun Ghaffari領導下的美國的Victor Gruen和伊朗的Aziz Farmanfarmaian所共同產生的(Ardalan,1986)。該計劃確定的城市的問題是:城市密度過高特別是城市中心、主要道路沿線商業活動的膨脹、污染、不完善的基礎設施,貧困地區廣泛的失業和低收入群體不斷地遷移到德黑蘭。解決的辦法是城市自然社會和經濟結構的轉型。(Farmanfarmaian and Gruen, 1968).不過該提案大多主張形態上的變化,試圖強調一個現代化的理念,強加這個復雜的都市的秩序。設想這個城市的未來可向西形成一個線性多中心的形式,減少密度和市中心的擠塞情況。全市將形成10個地區,其他各區由綠化帶隔開,每個地區約50萬居民,并設置擁有高樓的商業及工業中心。各個地區(mantagheh)將分為若干區域(nahyeh)和社區(mahalleh)。每個區域人口約1.5到3萬,有一所中學和商業中心以及其他必要設施。每個社區有大約5000居民,有一所小學和一個當地的商業中心。這些地區和區域將有相連的交通運輸網絡,包括高速公路,捷運路線及巴士路線。過境路線的站點會迅速發展為活動度高居住密度高的節點。重建及改善計劃中將有60萬人離開中心地區(Farmanfarmaian and Gruen, 1968).。
幾乎所有這些措施可以追溯到那個擁有時尚規劃理念的時代,這主要是受英國新城鎮的影響。在Victor Gruen的《我們城市的心臟》(1965)書中,曾設想未來的中心大 武漢科技大學本科畢業設計外文翻譯
都市會由10個城市包圍,每個國家都有它自己的中心。這很像Ebenezer Howard’s(1960年,第142頁)提到的,那個四周被園林城市群包圍著的中心城市:“社會的城市”。在德黑蘭的規劃中,這一概念的直譯版被使用。另一個在英國新城鎮被使用的概念,比如Redditch和 Runcorn,是把公共交通路線作為城市的骨架的重要性,其停車點是它的重點服務中心。使用鄰里中心和小學來限制鄰里單元人口,這被廣泛應用于這些新市鎮,這是一個曾在20世紀20年代在美國發展的想法(Mumford, 1954)。這些思想依然存在,但是,主要是在紙面上。該計劃已執行,已在美國城市規劃中有根深蒂固的想法,包括了用高速公路網的不斷延伸去連接城市的脫節部分;在不同地區的社會管理和物理性質的基礎上進行區劃;引進容積率的控制發展的密度。
在20世紀70年代進行的其他主要規劃工作包括Shahrak Gharb的局部發展新城鎮,以及Shahestan依照英國顧問Llewelyn–Davies提出的規劃新的城市行政中心,雖然這被當做正在上升的革命浪潮后來從未實施過。
革命和后革命時期可分為三個階段:革命(1979-1988年),重建(1989-1996年)和改革(1997-2004),每個都展示了德黑蘭城市規劃中不同的做法。
德黑蘭和其他城市經過兩年大量實證,1979年有代表性的是一個革命的到來推翻了伊朗君主,由議會共和制和神父統治的不穩定結合所取代。其原因可以追溯到在國王的發展模式導致了許多沖突,現代與傳統,經濟發展與政治發展,全球市場力量和地方資產階級力量,外國勢力和民族主義,腐敗和自滿中堅分子與不滿的群眾。像1906年的革命一樣,許多隱藏意見的累積使1979的革命成為可能。在第一次革命,維新已占了上風,而在第二次,傳統主義者贏得了領導。然而,無論革命的態度還是他們掌握政權之后的一系列重大問題,包括城市發展都顯示出現代化的偏好。從這個意義上講,該國的這兩個爆炸革命事件可以被看作是在動蕩中逐步轉型所作的努力(Madanipour,1998,2003)。革命是在與伊拉克長期戰爭(1980-1988)之后,其間停止了經濟的發展。在城市發展方面的投資減少,而農村地區和省城受到革命政府的青睞,同時遏制從農村向城市遷移并與大城市公平對待。在此期間主要規劃干預是對白天城市中心的私家車活動的限制。同時,戰爭和新政府的免費或低費用的設施,吸引了更多的人承諾向首都城市移民,到1986年人口達600萬。從20世紀50年代城市人口的增長速度已開始減慢,而直到80年代中期首都的增長都更快,但是它的增長率也開始下降(Khatam, 1993)。在革命和戰爭后,正常化和重建時期開始了,其中大部分持續到上世紀90年代。這期間見證了德黑蘭城市規劃的若干努力。但是沒有一個有效的框架來管理劇烈的城市發展。綜合計劃在革命后遭到攻擊,因為它被認為無法適應變化。1998年,市長批評它主要是形態上的發展規劃、植根于前政權的政治框架、并沒有足夠重視實際操作問題(Dehaghani,1995)。
綜合計劃的25年壽命在1991年結束。一個伊朗顧問公司(A-Tech)受委托于1985年籌備1986-1996期間的規劃。經過多次延遲,在1993年,該計劃最終被城市規劃高級理事會批準。該計劃還注重增長的管理和線性空間戰略,利用了城市區域,次區域,地 武漢科技大學本科畢業設計外文翻譯
區,小區和鄰里尺度。它促進保護、權力下放、多中心發展,有五個衛星新市鎮,并發展住宅增加城市密度。該協會建議,城市在5個亞區中被劃分成22個區,每個區都擁有自己的服務中心(Shahrdari-e Tehran, 2004)。
1993年的計劃不受市政當局歡迎,不同意它的估價和優先次序,認為它不現實、昂貴、無法實施。1996-2001年期間市政當局自己做了一個戰略規劃,它被認為是德黑蘭市政的第一個規劃或是德黑蘭80。它強調對一個城市提出戰略和政策來實現他們的第一個規劃,而不是以介紹土地利用規劃為目標。它把城市的主要問題確定為能提供服務的資源短缺、城市發展模式和速度、環境污染、缺乏有效的公共交通工具、效率低下和官僚主義。然后市政府對城市的未來遠景概述了六個主要特征:一個清潔的城市,建設便于運動的城市公園和綠化帶,新的文化和體育設施,改革發展的城市組織,以及對城市空間的改善,包括土地利用和保護的全面和詳細的計劃的編制規劃(Shahrdari-e Tehran, 1996)。
全市實施了1968年的計劃中提出的一部分建議,諸如增加南方的綠色開放空間,或是興建高速公路網;開放城市的大部分地區使之得到新的發展以緩解全城的運作。繼承1993年計劃的意見,市政府放寬容積率限制,并允許熱鬧地帶有更高的密度。然而,這并非基于規劃的考慮,主要是為了使市政當局的財政獨立。這在發展產業區廣受歡迎,但受到公民的爭議。開發者可以通過向市政府繳納罰款建立更高的建筑物,而不必考慮對周圍環境的影響,這個政策俗稱“密度銷售”。該城市的面貌,特別是在其北部地區,是在短期內改變的,其中包括中通過寬闊的街道和高速公路連接高樓大廈。在較貧窮的南部,一個大型的重建項目Navab穿過密集而破舊的建筑物建造高速公路,建立龐大的上層建筑的各個方面。這個城市的行政邊界擴大了兩次,一次向外,一次向西,涵蓋了700平方公里的22個區市。
這個時期的重建爭議隨著民主的改革而產生,它重新啟動了城市市議會的選舉,這首先造成了市長和市政府關系的制度混亂。該會于2001年公布了自己的城市構想作為德黑蘭憲章,這總結了大會上安理會成員、非政府組織和市政專家之間原則上同意的問題。該憲章主要采納了可持續性和民主性原則,被用于開發自然和處理環境、交通、社會、文化、經濟問題、城市管理戰略、區域性城市,國家和國際角色。
Development of the city of Tehran The city had grown in size and complexity to such an extent thatits spatial managementneeded additional tools, which resulted in the growing complexity of municipalorganization, and in the preparation of a comprehensive plan for the city.After the Second World War, during which the Allied forces occupied the country, there was a period of democratization, followed by political tensions of the start of the cold war, 武漢科技大學本科畢業設計外文翻譯
and struggles over the control of oil.This period was ended in 1953 by a coup detat that returned the Shah to power, who then acted as an executive monarch for the next 25 years.With high birth rates and an intensification of rural–urban migration, Tehran— and other large cities—grew even faster than before.By 1956, Tehran’s population rose to 1.5 million, by 1966 to 3 million, and by 1976 to 4.5 million;its size grew from 46 km2 in 1934 to 250 km2 in 1976(Kariman, 1976;Vezarat-e Barnameh va Budgeh, 1987).Revenues from the oil industry rose, creating surplus resources that needed to be circulated and absorbed in the economy.An industrialization drive from the mid-1950s created many new jobs in big cities, particularly in Tehran.The land reforms of the 1960s released large numbers of rural population from agriculture, which was not able to absorb the exponential demographic growth.This new labour force was attracted to cities: to the new industries, to the construction sector which seemed to be always booming, to services and the constantly growing public sector bureaucracy.Tehran’s role as the administrative, economic, and cultural centre of the country, and its gateway to the outside world, was firmly consolidated.Urban expansion in postwar Tehran was based on under-regulated, private-sector driven, speculative development.Demand for housing always exceeded supply, and a surplus of labor and capital was always available;hence the flourishing construction industry and the rising prices of land and property in Tehran.The city grew in a disjointed manner in all directions along the outgoing roads, integrating the surrounding towns and villages, and growing new suburban settlements.This intensified social segregation, destroyed suburban gardens and green spaces, and left the city managers feeling powerless.A deputy mayor of the city in 1962 commented that in Tehran, ‘‘the buildings and settlements have been developed by whomever has wanted in whatever way and wherever they have wanted’’, creating a city that was ‘‘in fact a number of towns connected to each other in an inappropriate way’’(Nafisi, 1964, p.426).There was a feeling that something urgently needed to be done, but the municipality was not legally or financially capable of dealing with this process.The 1966 Municipality Act provided, for the first time, a legal framework for the formation of the Urban Planning High Council and for the establishment of land-use planning in the form of comprehensive plans.A series of other laws followed, underpinning new legal and institutional arrangements for the Tehran municipality, allowing the Ministry of Housing and others to work together in managing the growth of the city.The most important step taken in planning was the approval of the Tehran Comprehensive Plan in 1968.It was produced by a consortium of Aziz Farmanfarmaian Associates of Iran and Victor Gruen Associates of the 武漢科技大學本科畢業設計外文翻譯
United States, under the direction of Fereydun Ghaffari, an Iranian city planner(Ardalan, 1986).The plan identified the city’s problems as high density, especially in the city centre;expansion of commercial activities along the main roads;pollution;inefficient infrastructure;widespread unemployment in the poorer areas, and the continuous migration of low-income groups to Tehran.The solution was to be found in the transformation of the city’s physical, social and economic fabric(Farmanfarmaian and Gruen, 1968).The proposals were, nevertheless, mostly advocating physical change, attempting, in a modernist spirit, to impose a new order onto this complex metropolis.The future of the city was envisaged to be growing westward in a linear polycentric form, reducing the density and congestion of the city centre.The city would be formed of 10 large urban districts, separated from each other by green belts,each with about 500,000 inhabitants, a commercial and an industrial centre with high-rise buildings.Each district(mantagheh)would be subdivided into a number of areas(nahyeh)and neighborhoods(mahalleh).An area, with a population of about 15–30,000, would have a high school and a commercial centre and other necessary facilities.A neighborhood, with its 5000 inhabitants, would have a primary school and a local commercial centre.These districts and areas would be linked by a transportation network, which included motorways, a rapid transit route and a bus route.The stops on the rapid transit route would be developed as the nodes for concentration of activities with a high residential density.A number of redevelopment and improvement schemes in the existing urban areas would relocate 600,000 people out of the central areas(Farmanfarmaian and Gruen, 1968).Almost all these measures can be traced to the fashionable planning ideas of the time, which were largely influenced by the British New Towns.In his book, The Heart of Our Cities, Victor Gruen(1965)had envisaged the metropolis of tomorrow as a central city surrounded by 10 additional cities,each with its own centre.This resembled Ebenezer Howard’s(1960, p.142)‘‘social cities’’, in which a central city was surrounded by a cluster of garden cities.In Tehran’s plan, a linear version of this concept was used.Another linear concept, which was used in the British New Towns of the time such as Redditch and Runcorn, was the importance of public transport routes as the town’s spine, with its stopping points serving as its foci.The use of neighborhood units of limited population, focused on a neighborhood centre and a primary school, was widely used in these New Towns, an idea that had been developed in the 1920s in the United States(Mumford, 1954).These ideas remained, however, largely on paper.Some of the plan’s ideas that were implemented, which were rooted in American city planning, included a network of freeways to connect the disjointed 武漢科技大學本科畢業設計外文翻譯
parts of the sprawling metropolis;zoning as the basis for managing the social and physical character of different areas;and the introduction of Floor Area Ratios for controlling development densities.Other major planning exercises, undertaken in the 1970s, included the partial development of a New Town, Shahrak Gharb, and the planning of a new administrative centre for the city—Shahestan—by the British consultants Llewelyn–Davies, although there was never time to implement the latter, as the tides of revolution were rising.Planning through policy development: reconstruction after the revolution and war The revolutionary and post-revolutionary period can be divided into three phases: revolution(1979–1988), reconstruction(1989–1996), and reform(1997–2004), each demonstrating different approaches to urban planning in Tehran.After two years of mass demonstrations in Tehran and other cities, the year 1979 was marked by the advent of a revolution that toppled the monarchy in Iran, to be replaced by a state which uneasily combined the rule of the clergy with parliamentary republicanism.Its causes can be traced in the shortcomings of the Shah’s model of development, which led to clashes between modernization and traditions, between economic development and political underdevelopment, between global market forces and local bourgeoisie, between foreign influence and nationalism, between a corrupt and complacent elite and discontented masses.Like the revolution of 1906, a coalition of many shades of opinion made the revolution of 1979 possible.In the first revolution, the modernizers had the upper hand, while in the second the traditionalists won the leadership.However, the attitudes of both revolutions—and the regimes that followed them—to a number of major issues, including urban development, show a preference for modernization.In this sense, both revolutions can be seen as explosive episodes in the country’s troubled efforts at progressive transformation(Madanipour, 1998, 2003).The revolution was followed by a long war(1980–1988)with Iraq, which halted economic development.Investment in urban development dwindled, while rural areas and provincial towns were favoured by the revolutionary government, both to curb rural–urban migration and to strike a balance with large cities.The key planning intervention in this period was to impose daytime restrictions on the movement of private cars in the city centre.Meanwhile, the war and the promise of free or low-cost facilities by the new government attracted more migrants to the capital city, its population reaching 6 million by 1986.The rate of population growth in the city had started to slow down from the 1950s, while the metropolitan region was growing faster until the mid-1980s, when its growth rate also started to decline(Khatam, 1993).After the revolution and war, a period of normalization and reconstruction started, which 武漢科技大學本科畢業設計外文翻譯
lasted for most of the 1990s.This period witnessed a number of efforts at urban planning in Tehran.Once again, urban development had intensified without an effective framework to manage it.The comprehensive plan came under attack after the revolution, as it was considered unable to cope with change.In 1998, the Mayor criticized it for being mainly a physical development plan, for being rooted in the political framework of the previous regime, and for not paying enough attention to the problems of implementation(Dehaghani, 1995).The comprehensive plan’s 25-year lifespan came to an end in 1991.A firm of Iranian consultants(A-Tech)was commissioned in 1985 to prepare a plan for the period of 1986–1996.After much delay, it was only in 1993 that the plan was finally approved by the Urban Planning High Council.This plan also focused on growth management and a linear spatial strategy, using the scales of urban region, subregion, district, area and neighbourhood.It promoted conservation, decentralization, polycentric development, development of five satellite new towns, and increasing residential densities in the city.It proposed that the city be divided into 22 districts within five sub-regions, each with its own service centre(Shahrdari-e Tehran, 2004).The 1993 plan was not welcomed by the municipality, which disagreed with its assessments and priorities, finding it unrealistic, expensive, and impossible to implement.The municipality produced its own strategic plan for the period 1996–2001, known as Tehran Municipalty’s First Plan, or Tehran 80.Rather than introducing a land-use plan as its goal, this was the first plan for the city that emphasized a set of strategies and propose d policies to achieve them.It identified the city’s main problems as shortage of resources to deliver its services;the pace and pattern of urban growth;environmental pollution;the absence of effective public transport, and inefficient bureaucracy.The municipality’s vision for the future of the city was then outlined to have six major characteristics: a clean city, ease of movement in the city, the creation of parks and green spaces, the development of new cultural and sports facilities, reform of the municipal organization, and planning for the improvement of urban space, including preparation of comprehensive and detailed plans for land use and conservation(Shahrdari-e Tehran, 1996).The municipality implemented part of the proposals, such as increasing the amount of green open spaces in the south, or constructing new parts of the motorway network, which was proposed by the 1968 plan;opening large parts of the city to new development, and easing movement across the city.Following the advice of the 1993 plan, the municipality relaxed FAR limits and allowed higher densities through bonus zoning.This, however, was not based on planning considerations, but was mainly to bring financial autonomy to the municipality.This proved to be popular with the development industry, but controversial with citizens.Developers could build taller buildings by paying fines to the municipality, in a 武漢科技大學本科畢業設計外文翻譯
policy popularly known as ‘‘selling density’’, without having to show their impacts on the surrounding environment.The face of the city, particularly in its northern parts, was transformed in a short period, consisting of medium to high-rise buildings connected through wide streets and motorways.In the poorer south, a major redevelopment project, Navab, cut a motorway through the dense and decayed fabric, building gigantic superstructures on each side.The city’s administrative boundaries were expanded twice, once outward and then westward, to encompass 22 district municipalities in 700 km2.This controversial period of reconstruction was followed by a period of democratic reform, which re-launched an elected city council for the city, which at first caused institutional confusion about its relationship with the mayor and the municipality.The council published its own vision of the city as Tehran Charter in 2001, which was the summary of the principles agreed between council members, non-governmental organizations, and urban experts at a congress about the subject.The Charter adopted sustainability and democracy as its key principles, which were used to develop strategies for natural and built environments, transport, social, cultural and economic issues, urban management, and the city’s regional, national and international roles.