大学毕业论文英文翻译及原文
毕业论文(设计)外文文献翻译及原文
金融体制、融资约束与投资——来自OECD的实证分析R．SemenovDepartment of Economics，University of Nijmegen，Nijmegen（荷兰内梅亨大学，经济学院）这篇论文考查了OECD的11个国家中现金流量对企业投资的影响.我们发现不同国家之间投资对企业内部可获取资金的敏感性具有显著差异,并且银企之间具有明显的紧密关系的国家的敏感性比银企之间具有公平关系的国家的低.同时，我们发现融资约束与整体金融发展指标不存在关系.我们的结论与资本市场信息和激励问题对企业投资具有重要作用这种观点一致，并且紧密的银企关系会减少这些问题从而增加企业获取外部融资的渠道。
一、引言各个国家的企业在显著不同的金融体制下运行。
金融发展水平的差别(例如，相对GDP的信用额度和相对GDP的相应股票市场的资本化程度），在所有者和管理者关系、企业和债权人的模式中，企业控制的市场活动水平可以很好地被记录.在完美资本市场,对于具有正的净现值投资机会的企业将一直获得资金。
然而，经济理论表明市场摩擦，诸如信息不对称和激励问题会使获得外部资本更加昂贵，并且具有盈利投资机会的企业不一定能够获取所需资本.这表明融资要素，例如内部产生资金数量、新债务和权益的可得性，共同决定了企业的投资决策.现今已经有大量考查外部资金可得性对投资决策的影响的实证资料（可参考，例如Fazzari（1998）、 Hoshi(1991)、 Chapman（1996）、Samuel(1998））.大多数研究结果表明金融变量例如现金流量有助于解释企业的投资水平。
这项研究结果解释表明企业投资受限于外部资金的可得性。
很多模型强调运行正常的金融中介和金融市场有助于改善信息不对称和交易成本，减缓不对称问题,从而促使储蓄资金投着长期和高回报的项目,并且提高资源的有效配置（参看Levine（1997)的评论文章）。
因而我们预期用于更加发达的金融体制的国家的企业将更容易获得外部融资.几位学者已经指出建立企业和金融中介机构可进一步缓解金融市场摩擦。
浙江大学本科毕业论文外文文献翻译
核准通过，归档资料。
未经允许，请勿外传!浙江大学本科毕业论文外文文献翻译The influence of political connections on the firm value of small and medium-sized enterprises in China政治关联在中国对中小型企业价值的影响1摘要中小型企业的价值受很多因素的影响,比如股东、现金流以及政治关联等.这篇文章调查的正是在中国政治关联对中小型企业价值的影响。
通过实验数据来分析政治关联对企业价值效益的影响.结果表明政府关联是关键的因素并且在中国对中小型企业的价值具有负面影响。
2重要内容翻译2。
1引言在商业界,有越来越多关于政治关联的影响的经济研究。
它们发现政治关联能够帮助企业确保有利的规章条件以及成功获得资源，比如能够最终提高企业价值或是提升绩效的银行贷款，这种政治关联的影响在不同的经济条件下呈现不同的效果。
在高腐败和法律制度薄弱的国家，政治关联对企业价值具有决定性因素1的作用.中国由高度集权的计划经济向市场经济转变，政府对市场具有较强的控制作用，而且有大量的上市企业具有政治关联。
中小型企业发展的很迅速，他们已经在全球经济环境中变得越来越重要。
从90年代起, 政治因素对中国的任何规模的企业来说都变得越来越重要,尤其是中小型企业的价值。
和其他的部门相比较，中小型企业只有较小的现金流，不稳定的现金流且高负债率.一方面，中小型企业改变更加灵活；另一方面,中小型企业在由于企业规模以及对银行来说没有可以抵押的资产，在筹资方面较为困难。
企业如何应对微观经济环境和政策去保证正常的企业活动，并且政治关联如何影响企业价值？这篇论文调查政治关联和企业价值之间的联系,并且试图去研究企业是否可以从政治关联中获利提升企业价值。
2.2定义这些中小型企业之所以叫中小型企业，是和管理规模有关。
对这些小企业来说，雇员很少，营业额较低,资金一般由较少的人提供,因此，通常由这些业主直接管理企业。
毕业论文外文翻译(中英文)
译文交通拥堵和城市交通系统的可持续发展摘要:城市化和机动化的快速增长,通常有助于城市交通系统的发展，是经济性，环境性和社会可持续性的体现,但其结果是交通量无情增加，导致交通拥挤。
道路拥挤定价已经提出了很多次，作为一个经济措施缓解城市交通拥挤，但还没有见过在实践中广泛使用，因为道路收费的一些潜在的影响仍然不明。
本文首先回顾可持续运输系统的概念,它应该满足集体经济发展,环境保护和社会正义的目标.然后,根据可持续交通系统的特点，使拥挤收费能够促进经济增长，环境保护和社会正义。
研究结果表明,交通拥堵收费是一个切实有效的方式，可以促进城市交通系统的可持续发展。
一、介绍城市交通是一个在世界各地的大城市迫切关注的话题。
随着中国的城市化和机动化的快速发展,交通拥堵已成为一个越来越严重的问题,造成较大的时间延迟,增加能源消耗和空气污染，减少了道路网络的可靠性．在许多城市,交通挤塞情况被看作是经济发展的障碍.我们可以使用多种方法来解决交通挤塞,包括新的基础设施建设，改善基础设施的维护和操作,并利用现有的基础设施,通过需求管理策略,包括定价机制,更有效地减少运输密度.交通拥堵收费在很久以前就已提出，作为一种有效的措施,来缓解的交通挤塞情况。
交通拥堵收费的原则与目标是通过对选择在高峰拥挤时段的设施的使用实施附加收费,以纾缓拥堵情况．转移非高峰期一些出行路线,远离拥挤的设施或高占用车辆，或完全阻止一些出行,交通拥堵收费计划将在节省时间和降低经营成本的基础上,改善空气中的质量，减少能源消耗和改善过境生产力。
此计划在世界很多国家和地方都有成功的应用。
继在2０世纪70年代初和8０年代中期挪威与新加坡实行收费环,在20０３年2月伦敦金融城推出了面积收费；直至现在,它都是已经开始实施拥挤收费的大都市圈中一个最知名的例子。
然而,交通拥堵收费由于理论和政治的原因未能在实践中广泛使用。
道路收费的一些潜在的影响尚不清楚,和城市发展的拥塞定价可持续性,需要进一步研究。
毕业论文 翻译材料(中英)
原文Sometimes it becomes apparent that previous approaches to a problem haven’t quite worked the way you anticipated.Perhaps you just need to clear away the smoky residue of the past,take a deep breath,and try again with a new attitude and fresh ideas. In golf,it’s known as a“mulligan”;in schoolyard sports,it’s called a “do-over”;and in the computer industry,we say it’s a“reboot.”A reboot is what Microsoft has initiated with its new approach to the mobile phone market.With its clean look,striking fonts,and new organizational paradigms, Microsoft Windows Phone7not only represents a break with the Windows Mobile past but also differentiates itself from other smartphones currently in the market. Windows Phone7devices will be made by several manufacturers and available with a variety of cell providers.For programmers,Windows Phone7is also exciting,for it supports two popular and modern programming platforms:Silverlight and XNA.Silverlight—a spinoff of the client-based Windows Presentation Foundation (WPF)—has already given Web programmers unprecedented power to develop sophisticated user interfaces with a mix of traditional controls,high-quality text, vector graphics,media,animation,and data binding that run on multiple platforms and browsers.Windows Phone7extends Silverlight to mobile devices.XNA—the three letters stand for something like“XNA is Not an Acronym”—is Microsoft’s game platform supporting both2D sprite-based and3D graphics with a traditional game-loop architecture.Although XNA is mostly associated with writing games for the Xbox360console,developers can also use XNA to target the PC itself, as well as Microsoft’s classy audio player,the Zune HD.Either Silverlight or XNA would make good sense as the sole application platform for the Windows Phone7,but programmers have a choice.And this we call“an embarrassment of riches.”Targeting Windows Phone7All programs for Windows Phone7are written managed code.Although the sample programs in this book are written in the C#programming language,it is also possible to write Windows Phone7applications in Visual .The free downloadable Microsoft Visual Studio2010Express for Windows Phone includes XNA Game Studio4.0 and an on-screen phone emulator,and also integrates with Visual Studio2010.You can develop visuals and animations for Silverlight applications using Microsoft Expression Blend.2The Silverlight and XNA platforms for Windows Phone7share some libraries,and you can use some XNA libraries in a Silverlight program and vice versa.But you can’t create a program that mixes visuals from both platforms.Maybe that will be possible in the future,but not now.Before you create a Visual Studio project,you must decide whether your million-dollar idea is a Silverlight program or an XNA program. Generally you’ll choose Silverlight for writing programs you might classify as applications or utilities.These programs are built from a combination of markup and code.The markup is the Extensible Application Markup Language,or XAML andpronounced“zammel.”The XAML mostly defines a layout of user-interface controls and panels.Code-behind files can also perform some initialization and logic,but are generally relegated to handling events from the controls.Silverlight is great for bringing to the Windows Phone the style of Rich Internet Applications(RIA), including media and the Web.Silverlight for Windows Phone is a version of Silverlight3excluding some features not appropriate for the phone,but compensating with some enhancements.XNA is primarily for writing high-performance games.For2D games,you define sprites and backgrounds based around bitmaps;for3D games you define models in3D space. The action of the game,which includes moving graphical objects around the screen and polling for user input,is synchronized by the built-in XNA game loop.The differentiation between Silverlight-based applications and XNA-based games is convenient but not restrictive.You can certainly use Silverlight for writing games and you can even write traditional applications using XNA,although doing so might sometimes be challenging.In particular,Silverlight might be ideal for games that are less graphically oriented,or use vector graphics rather than bitmap graphics,or are paced by user-time rather than clock-time.A Tetris-type program might work quite well in Silverlight.You’ll probably find XNA to be a bit harder to stretch into Silverlight territory,however.Implementing a list box in XNA might be considered“fun”by some programmers but a torture by many others.The first several chapters in this book describe Silverlight and XNA together,and then the book splits into different parts for the two platforms.I suspect that some developers will stick with either Silverlight or XNA exclusively and won’t even bother learning the other environment.I hope that’s not a common attitude.The good news is that Silverlight and XNA are so dissimilar that you can probably bounce back and forth between them without confusion!Microsoft has been positioning Silverlight as the front end or“face”of the cloud, so cloud services and Windows Azure form an important part of Windows Phone7 development.The Windows Phone is“cloud-ready.”Programs are location-aware and have access to maps and other data through Bing and Windows Live.One of the available cloud services is Xbox Live,3which allows XNA-based programs to participate in online multiplayer games,and can also be accessed by Silverlight applications.Programs you write for the Windows Phone7will be sold and deployed through the Windows Phone Marketplace,which provides registration services and certifies that programs meet minimum standards of reliability,efficiency,and good behavior. I’ve characterized Windows Phone7as representing a severe break with the past. If you compare it with past versions of Windows Mobile,that is certainly true.But the support of Silverlight,XNA,and C#are not breaks with the past,but a balance of continuity and innovation.As young as they are,Silverlight and XNA have already proven themselves as powerful and popular platforms.Many skilled programmers are already working with either one framework or the other—probably not so many withboth just yet—and they have expressed their enthusiasm with a wealth of online information and communities.C#has become the favorite language of many programmers (myself included),and developers can use C#to share libraries between their Silverlight and XNA programs as well as programs for environments. The Hardware ChassisDevelopers with experience targeting Windows Mobile devices of the past will find significant changes in Microsoft’s strategy for the Windows Phone7.Microsoft has been extremely proactive in defining the hardware specification,often referred to as a“chassis.”Initial releases of Windows Phone7devices will have one consistent screen size.(A second screen size is expected in the future.)Many other hardware features are guaranteed to exist on each device.The front of the phone consists of a multi-touch display and three hardware buttons generally positioned in a row below the display.From left to right,these buttons are called Back,Start,and Search:•Back Programs can use this button for their own navigation needs,much like the Back button on a Web browser.From the home page of a program,the button causes the program to terminate.•Start This button takes the user to the start screen of the phone;it is otherwise inaccessible to programs running on the phone.4•Search The operating system uses this button to initiate a search feature.The initial releases of Windows Phone7devices have a display size of480×800 pixels.In the future,screens of320×480pixels are also expected.There are no other screen options for Windows Phone7,so obviously these two screen sizes play a very important role in phone development.In theory,it’s usually considered best to write programs that adapt themselves to any screen size,but that’s not always possible,particularly with game development.You will probably find yourself specifically targeting these two screen sizes,even to the extent of having conditional code paths and different XAML files for layout that is size-dependent.I will generally refer to these two sizes as the“large”screen and the “small“screen.The greatest common denominator of the horizontal and vertical dimensions of both screens is160,so you can visualize the two screens as multiples of160-pixel squares:480320480800I’m showing these screens in portrait mode because that’s usually the way smartphones are designed.The screen of the original Zune is240×320pixels;the Zune HD is272×480.Of course,phones can be rotated to put the screen into landscape mode.Some programs might require the phone to be held in a certain orientation;others might be moreadaptable.You have complete control over the extent to which you support orientation.By default,Silverlight applications appear in portrait mode,but you’ll probably want to write your Silverlight applications so they adjust themselves to orientation changes.New events are available specifically for the purpose of detecting orientation change,and some orientation shifts are handled automatically.In contrast,game programmers can usually impose a particular orientation on the user. XNA programs use landscape mode by default,but it’s easy to override that.5In portrait mode,the small screen is half of an old VGA screen(that is,640×480).In landscape mode,the large screen has a dimension sometimes called WVGA (“wide VGA”).In landscape mode,the small screen has an aspect ratio of3:2or 1.5;the large screen has an aspect ratio of5:3or1.66….Neither of these matches the aspect ratio of television,which for standard definition is4:3or1.33…and for high-definition is16:9or1.77….The Zune HD screen has an aspect ratio of 16:9.Like many recent phones and the Zune HD,the Windows Phone7displays will likely use OLED(“organic light emitting diode”)technology,although this isn’t a hardware requirement.OLEDs are different from flat displays of the past in that power consumption is proportional to the light emitted from the display.For example, an OLED display consumes less than half the power of an LCD display of the same size, but only when the screen is mostly black.For an all-white screen,an OLED consumes more than three times the power of an LCD.Because battery life is extremely important on mobile devices,this characteristic of OLED displays implies an aesthetic of mostly black backgrounds with sparse graphics and light-stroked fonts.Regardless,Windows Phone7users can choose between two major color themes:light text on a dark background,or dark text on a light background.Most user input to a Windows Phone7program will come through multi-touch.The screens incorporate capacitance-touch technology,which means that they respond to a human fingertip but not to a stylus or other forms of pressure.Windows Phone7 screens are required to respond to at least four simultaneous touch-points.A hardware keyboard is optional.Keep in mind that phones can be designed in different ways,so when the keyboard is in use,the screen might be in either portrait mode or landscape mode.A Silverlight program that uses keyboard input must respond to orientation changes so that the user can both view the screen and use the keyboard without wondering what idiot designed the program sideways.An on-screen keyboard is also provided,known in Windows circles as the Soft Input Panel or SIP.XNA programs also have access to the hardware keyboard and SIP.译文有时候以前的方法显然无法达到预期效果，这时也许需要告别迷雾茫茫的过去。
毕业论文的外文译文
毕业论文的外文译文Due to the increasing importance of communication and cooperation in today's globalized world, businesses are constantly looking for ways to improve their cross-cultural communication skills. One area where these skills are crucial is in the internationalization of companies, where firms require a deep understanding of the cultural differences in order to be successful. This requires a comprehensive understanding of not only language, but also the cultural norms and values of the target market. In this thesis, we will explore the importance of cross-cultural communication in international businesses and how it can be improved.The primary challenge in cross-cultural communication is the language barrier. While English is the dominant language in international business, many firms find that it's not enough to communicate effectively with their target market. There are cultural differences in the way people use language, as well as differences in nonverbal communication such as body language and facial expressions. For instance, in Japan, it's common to nod and smile even if one does not agree with astatement, whereas in the United States, a lack of disagreement often means agreement. These differences can lead to misunderstandings in business conversations, which can ultimately harm business relationships.In order to overcome these language barriers, companies need to invest in language training for their employees. This training should focus not only on the language itself, but also on the cultural norms and values associated with the language. For example, a Japanese training program might teach students about the concepts of harmony and respect in Japanese culture, and how these values influence the way people communicate with each other. By understanding these cultural norms, employees will be able to communicate more effectively with their Japanese counterparts.Another challenge in cross-cultural communication is understanding the cultural context of business interactions. In some cultures, business is conducted in a more formal manner, with a strong emphasis on hierarchy and protocol. In other cultures, business is more informal and relaxed. Companies need to understand these differences in order to work effectively in international markets.To overcome these context challenges, companies should incorporate cultural training into their employee training programs. Cultural training should focus on the history, customs, and traditions of the target market. It should also address the specific business practices and protocol required for success in that market.In conclusion, cross-cultural communication is a key determinant of success in international businesses. In order to succeed in foreign markets, companies must have a deep understanding of the language, cultural norms, and values of their target market. This requires a comprehensive training program that not only focuses on language skills, but also on the cultural context of business interactions. With the right training and support, companies can improve their cross-cultural communication skills and achieve success in global markets.。
毕业论文英语翻译及原文
=H（ - ）（1）
respectively, the expression can be easily gained as follows
Then, the relation equation between the two baseline vectors is expressedas
There are two steps in the GPS observation data processing course. They are baseline calculationand network adjustment. The baseline vectors in WGS-84 can be firstly got using baseline calculation.Secondly, the baseline vector transformation from WGS-84 to the station orthogonal coordinatesystem can be done with (3). At last, the adjustment of GPS deformatihestation orthogonal coordinate system can be successfully finished.
If the position vector of the station orthogonal coordinate system originP0inWGS-84 isexpressed as = , according to thegeodetic latitude and longitude（ ， ）, theposition vector
毕业论文英文翻译
毕业论文英文翻译Title: The Impact of Artificial Intelligence on Employment Abstract:This paper explores the impact of artificial intelligence (AI) on employment. The rise of AI technologies has sparked concerns about its potential to replace human jobs. Through an analysis of existing literature and case studies, this study investigates the ways in which AI has affected various industries and job sectors. The findings indicate that while AI has the potential to automate certain tasks and reduce the need for human intervention, it also creates new job opportunities and contributes to economic growth. Additionally, the study highlights the importance of retraining and upskilling workers to adapt to the changing job market. Overall, this research contributes to a better understanding of the complex relationship between AI and employment and provides insights into proactive strategies to address the challenges posed by AI. Introduction:Artificial intelligence has emerged as a powerful technology with the potential to transform various aspects of society, including the workforce. The rapid advancement of AI has raised concerns about potential job losses and increased automation. This study aims to explore the impact of AI on employment and identify strategies to mitigate negative effects. By examining existing literature and case studies, this research provides a comprehensive analysis of AI's influence on different industries and job sectors.Literature Review:The literature offers a wide range of perspectives on the impact ofAI on employment. Some studies suggest that AI will lead to significant job losses in sectors such as manufacturing, transportation, and customer service. They argue that AI technologies, such as autonomous vehicles and chatbots, can perform tasks previously done by humans more efficiently and at a lower cost. On the other hand, other studies argue that AI will create new job opportunities and enhance productivity. For example, the healthcare sector benefits from AI technologies by improving diagnosis accuracy and streamlining administrative processes.Case Studies:This study includes several case studies that examine the impact of AI on specific industries. The manufacturing industry, for instance, has experienced both job losses and job creation due to the introduction of AI. While certain tasks have been automated, new roles related to AI maintenance and programming have emerged. Similarly, the retail industry has witnessed the integration of AI technologies, leading to job displacement in traditional retail jobs but also the creation of new positions in data analysis and online customer support.Mitigation Strategies:To address the challenges posed by AI, strategies should focus on retraining and upskilling the workforce to adapt to the changing job market. Governments and organizations should encourage workers to acquire in-demand skills such as data analysis and AI programming. Additionally, collaboration between academia and industry is crucial to ensure that education and training programs remain relevant and effective. Finally, policies that support jobtransition and income support for displaced workers will help minimize the negative impact of AI on employment. Conclusion:The impact of artificial intelligence on employment is a complex and multifaceted issue. While concerns about job losses are valid, it is important to recognize that AI also creates new job opportunities and contributes to economic growth. By implementing proactive strategies, such as retraining and upskilling, societies can better navigate the changes brought about by AI and ensure a future where humans and machines can coexist harmoniously.。
大学毕业论文英文翻译及原文
大学毕业论文英文翻译中文译文计算机网络每个一个世纪都有一种主导地位的技术。
18世纪伴随着工业革命的到来的是大型机械系统的时代；19世纪是蒸汽机的时代，而20世纪的发展历程中，关键的技术是信息收集、处理和分发。
在其他的发展方面，我们还可以看到：遍布全球的电话网络的建立起来了，无线电广播和电视的出现了，计算机工业诞生了，并且以超乎想象的速度在成长；另外通信卫星也发射上天了。
技术的快速发展的一个直接结果是，这些领域正在快速地融合，信息收集、传输、存储和处理之间的差别正在迅速地消失。
对于具有数百个办公室的大型组织来说，尽管这些办公室分布在广阔的地理区域中，但未来期望的情景是，工作人员只要单击一下按钮，就可以查看最远处分部的状态。
随着信息收集、处理和分发能力的不断提高，我们对于更加复杂的信息处理技术的需求也增长得更快。
与其他的工业(比如汽车和航空运输业)相比，计算机工业还是非常年轻，尽管如此，计算机技术却在很短的时间内有了惊人的进展。
在计算机诞生之初的20年间，计算机系统是高度集中化的，通常位于一个很大的房间中。
该房间通常配有玻璃墙，参观的人透过玻璃墙可以欣赏到里边伟大的电子奇迹。
中等规模的公司或者大学可能会有一台或者两台计算机，而大型的研究机构最多也就几十台计算机。
要在20年内生产出大量同样功能但是体积比邮票还小的计算机，在当时的人们看来纯属科学幻想。
计算机和通信的结合对于计算机系统的组织方式产生了深远的影响。
把一台大型的计算机放在一个单独的房间中，然后用户带着他们的处理任务去房间里上机，这种"计算机中心"的概念现在已经完全过时了。
由一台计算机来处理整个组织中所有的计算需求，这种老式的模型已经被新的模型所取代，在新的模型下，由大量独立的，但相互连接起来的计算机来共同完成计算任务。
这些系统称为计算机网络(computer networks)。
如何设计这些网络，并且将这些网络组织起来，这就是本书的主题。
毕业论文英文原文
毕业论文英文原文Graduation Thesis: English Original TextAbstract:This graduation thesis aims to explore the impact of technology on education. It delves into the advantages and disadvantages of integrating technology into the classroom, while also discussing the potential challenges and future prospects. The research provides insights into the evolving role of technology in education and its implications for students, teachers, and educational institutions. Introduction:In recent years, technology has revolutionized various aspects of our lives, including education. The integration of technology in the classroom has become a topic of great interest and debate. This thesis seeks to examine the English original text of my graduation paper, which focuses on the impact of technology on education. By analyzing the benefits and drawbacks of technology in the classroom, this research aims to shed light on the evolving educational landscape.Advantages of Integrating Technology in the Classroom:One of the significant advantages of integrating technology in the classroom is enhanced engagement and interactivity. Technology provides students with interactive learning experiences, making education more enjoyable and effective. For example, educational apps and online platforms offer personalized learning opportunities, catering to individual student needs and learning styles.Furthermore, technology facilitates access to a vast amount of information and resources. The internet allows students to explore various topics beyond the limitations of traditional textbooks. Online databases, e-books, and educational videos provide students with a wealth of knowledge at their fingertips.In addition, technology promotes collaboration and communication among students. Platforms such as video conferencing and online discussion forums enable students to connect with peers from different locations, fostering cultural exchange and global awareness.Disadvantages and Challenges:Despite the numerous advantages, there are also potential disadvantages and challenges associated with integrating technology in the classroom. One of the primary concerns is the digital divide. Not all students have equal access to technology and the internet, leading to inequalities in educational opportunities. This issue must be addressed to ensure equitable access to educational resources for all students.Another challenge is the potential for distractions. With the increasing use of personal devices in the classroom, students may be tempted to engage in non-educational activities, such as social media or gaming. Teachers must find effective strategies to minimize distractions and maintain a focused learning environment.Moreover, the rapid pace of technological advancements poses a challenge for teachers to keep up with the latest tools and techniques. Continuousprofessional development is crucial to ensure educators are equipped with the necessary skills to effectively integrate technology into their teaching practices. Future Prospects:Looking ahead, the future prospects of technology in education are promising. As technology continues to advance, innovative tools and platforms will emerge, providing even more immersive and personalized learning experiences. Artificial intelligence and virtual reality are already being integrated into educational settings, offering new possibilities for interactive learning.Furthermore, the COVID-19 pandemic has accelerated the adoption of technology in education. Online learning platforms and remote teaching have become essential during times of crisis. This experience has highlighted the importance of technology in ensuring continuity of education, even in challenging circumstances.Conclusion:In conclusion, the English original text of my graduation thesis explores the impact of technology on education. It discusses the advantages of integrating technology in the classroom, such as enhanced engagement, access to information, and collaboration. However, it also acknowledges the challenges, including the digital divide and potential distractions. Looking forward, technology holds great potential to transform education and provide students with innovative learning experiences. It is essential for educators and policymakers to navigate these advancements thoughtfully and ensure equalaccess to quality education for all.。
毕业论文英语翻译
毕业论文英语翻译Graduation Thesis- English Translation(700 words)Title: Impact of Social Media on Youth: A Comparative Study of China and the United StatesAbstract:This graduation thesis aims to explore and compare the impact of social media on youth in China and the United States. With the rapid development of technology, social media platforms have become an integral part of the daily lives of young people across the globe. This research focuses on understanding the extent to which social media influences their behavior, mental health, interpersonal relationships, and overall well-being. By conducting a comparative study between China and the United States, this thesis seeks to highlight the cultural differences and similarities in the utilization and effects of social media on youth in the two countries. Through the use of surveys, interviews, and analysis of existing literature, the research findings provide valuable insights to inform policymakers, educators, and parents on how to address the challenges and harness the opportunities presented by social media.Introduction:Social media platforms, such as WeChat, Weibo, Facebook, and Instagram, have become an integral part of daily life for young people around the world. With the increasing prevalence of smartphones, young people have unprecedented access to these platforms. This thesis focuses on understanding the influence ofsocial media on youth, as it has both positive and negative effects. For instance, social media has allowed young people to stay connected with friends, express themselves, and gain access to information. On the other hand, excessive use of social media can lead to mental health issues, cyberbullying, and reduced face-to-face social interaction.Methodology:To achieve the objectives of this thesis, a mixed-methods approach is adopted. A quantitative survey will be conducted among a sample of Chinese and American youth to collect data on their social media usage, behavioral changes, mental health, and relationship dynamics. Additionally, qualitative interviews will be conducted to gain deeper insights into their experiences and perceptions of social media. The analysis of existing studies and literature on social media will complement the primary data collected.Findings:Preliminary analysis suggests that Chinese and American youth have differing patterns of social media use. While Chinese youth tend to use platforms like WeChat and Weibo predominantly for communication, American youth often utilize platforms like Facebook and Instagram for personal expression. Moreover, Chinese youth show a higher inclination towards comparing themselves to others on social media, whereas American youth tend to engage in cyberbullying and online harassment more frequently. Both Chinese and American youth report experiencing anxiety and depression as a result of their social media use, albeit for different reasons.Conclusion:This research provides valuable insights into the impact of social media on the youth population in China and the United States. The comparative analysis highlights the cultural differences in social media usage and effects. The findings suggest the need for targeted interventions and policies to address the challenges posed by social media, such as cyberbullying and mental health issues. Additionally, the research emphasizes the importance of digital literacy education for young people to navigate the complexities of social media in a responsible and informed manner. Keywords: social media, youth, China, United States, comparative study。
毕业论文英文文献翻译
毕业论文英文文献翻译Graduation Thesis: Translation of English LiteratureIntroductionThe process of writing a graduation thesis can be a daunting task, especially when it involves the translation of English literature. Translating literary works requires not only language proficiency but also a deep understanding of the cultural nuances and literary techniques employed by the author. In this article, we will explore the challenges and strategies involved in translating English literature for a graduation thesis.Understanding the Source TextBefore embarking on the translation process, it is crucial to thoroughly understand the source text. This involves a careful reading and analysis of the original work, paying attention to the author's style, tone, and literary devices. By immersing oneself in the source text, the translator gains a deeper understanding of the author's intentions and can effectively convey the essence of the work in the target language.Translating Cultural NuancesOne of the most significant challenges in translating English literature is capturing the cultural nuances embedded in the text. Literature often reflects the social, historical, and cultural context in which it was written. Translating these nuances requires the translator to have a comprehensive knowledge of both the source and target cultures. It is essential to find equivalent expressions, idioms,or metaphors that resonate with the target audience while staying true to the original intent of the author.Maintaining Literary TechniquesEnglish literature is renowned for its rich use of literary techniques such as symbolism, imagery, and wordplay. Translating these techniques poses a considerable challenge as they may not have direct equivalents in the target language. The translator must strive to retain the artistic essence of the original work while adapting it to the linguistic and cultural constraints of the target language. This requires creativity and a keen eye for detail to ensure that the translated work captures the same aesthetic impact as the source text. Adapting to Linguistic DifferencesLanguages differ not only in vocabulary but also in grammatical structures and syntax. Translating English literature into another language often involves adapting the sentence structure and grammar to ensure fluency and coherence in the target language. The translator must strike a delicate balance between staying faithful to the original text and making necessary adjustments to ensure readability and comprehension for the target audience.The Role of the TranslatorA translator of English literature for a graduation thesis is not merely a conduit for transferring words from one language to another. They are responsible for bridging the gap between cultures, enabling readers to experience the essence of the original work in their native language. A successful translator mustpossess a deep appreciation for both the source and target cultures, as well as the literary techniques employed by the author. They must strive to create a translation that captures the spirit of the original work while being accessible and engaging to the target audience.ConclusionTranslating English literature for a graduation thesis is a challenging yet rewarding endeavor. It requires a combination of linguistic proficiency, cultural understanding, and literary sensibility. By carefully analyzing the source text, capturing cultural nuances, maintaining literary techniques, adapting to linguistic differences, and embodying the role of a translator, one can successfully translate English literature for a graduation thesis. Through this process, the translator not only contributes to academic research but also fosters cross-cultural understanding and appreciation for the beauty of literature.。
毕业设计论文翻译（译文+原文）
Hacking tricks toward security on network environments Tzer-Shyong Chen1, Fuh-Gwo Jeng 2, and Yu-Chia Liu 11 Department of Information Management, Tunghai University, Taiwan2 Department of Applied Mathematics, National Chiayi University, TaiwanE-Mail:****************.edu.twAbstractMounting popularity of the Internet has led to the birth of Instant Messaging, an up-and-coming form of Internet communication. Instant Messaging is very popular with businesses and individuals since it has instant communication ability. As a result, Internet security has become a pressing and important topic for discussion. Therefore, in recent years, a lot of attention has been drawn towards Internet security and the various attacks carried out by hackers over the Internet. People today often handle affairs via the Internet. For instance, instead of the conventional letter, they communicate with others by e-mails; they chat with friends through an instant messenger; find information by browsing websites instead of going to the library; perform e-commerce transactions through the Internet, etc. Although the convenience of the Internet makes our life easier, it is also a threat to Internet security. For instance, a business email intercepted during its transmission may let slip business confidentiality; file transfers via instant messengers may also be intercepted, and then implanted with backdoor malwares; conversations via instant messengers could be eavesdropped. Furthermore, ID and password theft may lose us money when using Internet bank service. Attackers on the Internet use hacking tricks to damage systems while users are connected to the Internet. These threats along with possible careless disclosure of business information make Instant Messaging a very unsafe method of communication for businesses. The paper divides hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing or fraud via e-mails. (3) Fake Websites. Keywords:Hacking tricks, Trojan programs, Phishing, Firewall, Intrusion detection system.1. IntroductionIncreasingly more people are using instant messengers such as MSN Messenger, Yahoo! Messenger, ICQ, etc as the media of communication. These instant messengers transmit alphanumeric message as well as permit file sharing. During transfer, a file may be intercepted by a hacker and implanted with backdoor malware. Moreover, the e-mails users receive every day may include Spam, advertisements, and fraudulent mail intended to trick uninformed users. Fake websites too are prevalent. Websites which we often visit could be counterfeited by imitating the interface and the URL of the original, tricking users. The paper classifies hacking tricks into three categories which are explained in the following sections.2. Hacking TricksThe paper divides hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing (3) Fake Websites.2.1 Trojan programs that share files via instant messengerInstant messaging allows file-sharing on a computer [9]. All present popular instant messengers have file sharing abilities, or allow users to have the above functionality by installing patches or plug-ins; this is also a major threat to present information security. These communication softwares also makeit difficult for existing hack prevention methods to prevent and control information security. Therefore, we shall discuss how to control the flow of instant messages and how to identify dangerous user behavior.Hackers use instant communication capability to plant Trojan program into an unsuspected program; the planted program is a kind of remotely controlled hacking tool that can conceal itself and is unauthorized. The Trojan program is unknowingly executed, controlling the infected computer; it can read, delete, move and execute any file on the computer. The advantages of a hacker replacing remotely installed backdoor Trojan programs [1] with instant messengers to access files are:When the victim gets online, the hacker will be informed. Thus, a hacker can track and access the infected computer, and incessantly steal user information.A hacker need not open a new port to perform transmissions; he can perform his operations through the already opened instant messenger port.Even if a computer uses dynamic IP addresses, its screen name doesn’t change.Certain Trojan programs are designed especially for instant messengers. These Trojans can change group settings and share all files on the hard disk of the infected computer. They can also destroy or modify data, causing data disarray. This kind of program allows a hacker access to all files on an infected computer, and thus poses a great threat to users. The Trojan program takes up a large amount of the resources of the computer causing it to become very slow and often crashes without a reason.Trojan programs that access a user computer through an instant messenger are probably harder to detect than classic Trojan horse programs. Although classic Trojan intrudes a computer by opening a listening or outgoing port which is used to connect toa remote computer, a desktop firewall can effectively block such Trojans. Alternatively, since it is very difficult for the server’s firewall to spot intrusion by controlling an instant messenger’s flow, it is extremely susceptible to intrusion.Present Trojan programs have already successfully implemented instant messengers. Some Trojan programs are Backdoor Trojan, AIMVision, and Backdoor. Sparta.C. Backdoor Trojans use ICQ pager to send messages to its writer. AIMVision steals AIM related information stored in the Windows registry, enabling a hacker to setup an AIM user id. Backdoor. Sparta.C uses ICQ to communicate with its writer and opens a port on an infected host and send its IP Address to the hacker, and at the same time attempts to terminate the antivirus program or firewall of the host.2.1.1 Hijacking and ImpersonationThere are various ways through which a hacker can impersonate other users [7]. The most commonly used method is eavesdropping on unsuspecting users to retrieve user accounts, passwords and other user related information.The theft of user account number and related information is a very serious problem in any instant messenger. For instance, a hacker after stealing a user’s information impersonate the user; the user’s contacts not knowing that the user’s account has been hacked believe that the person they’re talking to is the user, and are persuaded to execute certain programs or reveal confidential information. Hence, theft of user identity not only endangers a user but also surrounding users. Guarding against Internet security problems is presently the focus of future research; because without good protection, a computer can be easily attacked, causing major losses.Hackers wishing to obtain user accounts may do so with the help of Trojans designed to steal passwords. If an instant messenger client stores his/her password on his/her computer, then a hacker can send a Trojan program to the unsuspecting user. When the user executes the program, the program shall search for the user’s password and send it to the hacker. There are several ways through which a Trojan program can send messages back to the hacker. The methods include instant messenger, IRC, e-mails, etc.Current four most popular instant messengers are AIM, Yahoo! Messenger, ICQ, and MSN Messenger, none of which encrypts its flow. Therefore, a hackercan use a man-in-the-middle attack to hijack a connection, then impersonate the hijacked user and participate in a chat-session. Although difficult, a hacker can use the man-in-the-middle attack to hijack the connection entirely. For example, a user may receive an offline message that resembles that sent by the server, but this message could have been sent by the hacker. All at once, the user could also get disconnected to the server. Furthermore, hackers may also use a Denial of Service (DoS) tool or other unrelated exploits to break the user’s connection. However, the server keeps the connection open, and does not know that the user has been disconnected; thus allowing the hacker to impersonate the user. Moreover, since the data flow is unencrypted and unauthenticated, a hacker can use man-in-the-middle attacks that are similar to that of ARP fraud to achieve its purpose.2.1.2 Denial of Service (DoS)There are many ways through which a hacker can launch a denial of service (DoS) attack [2] on an instant messenger user. A Partial DoS attack will cause a user end to hang, or use up a large portion of CPU resources causing the system to become unstable.Another commonly seen attack is the flooding of messages to a particular user. Most instant messengers allow the blocking of a particular user to prevent flood attacks. However, a hacker can use tools that allow him to log in using several different identities at the same time, or automatically create a large number of new user ids, thus enabling a flood attack. Once a flood attack begins, even if the user realizes that his/her computer has been infected, the computer will not be able to respond. Thus, the problem cannot be solved by putting a hacker’s user id on the ignore list of your instant messenger.A DoS attack on an instant messenger client is only a common hacking tool. The difficulty of taking precautions against it could turn this hacking tool into dangerous DoS type attacks. Moreover, some hacking tools do not just cause an instant messenger client to hang, but also cause the user end to consume large amount of CPU time, causing the computer to crash.2.1.3 Information DisclosureRetrieving system information through instant messenger users is currently the most commonly used hacking tool [4]. It can effortlessly collect user network information like, current IP, port, etc. IP address retriever is an example. IP address retrievers can be used to many purposes; for instance, a Trojan when integrated with an IP address retriever allows a hacker to receive all information related to the infected computer’s IP address as soon as the infected computer connects to the internet. Therefore, even if the user uses a dynamic IP address, hackers can still retrieve the IP address.IP address retrievers and other similar tools can also be used by hackers to send data and Trojans to unsuspecting users. Hackers may also persuade unsuspecting users to execute files through social engineering or other unrelated exploits. These files when executed search for information on the user’s computer and sends them back to the hacker through the instant messenger network.Different Trojan programs were designed for different instant messaging clients. For example, with a user accounts and password stealing Trojans a hacker can have full control of the account once the user logs out. The hacker can thus perform various tasks like changing the password and sending the Trojan program to all of the user’s contacts.Moreover, Trojans is not the only way through which a hacker can cause information disclosure. Since data sent through instant messengers are unencrypted, hackers can sniff and monitor entire instant messaging transmissions. Suppose an employee of an enterprise sends confidential information of the enterprise through the instant messenger; a hacker monitoring the instant messaging session can retrieve the data sent by the enterprise employee. Thus, we must face up to the severity of the problem.2.2 PhishingThe word “Phishing” first appeared in 1996. It is a variant of ‘fishing’, and formed by replacing the ‘f’ in ‘fishing’ with ‘ph’ from phone. It means tricking users of their money through e-mails.Based on the statistics of the Internet Crime Complaint Center, loss due to internet scam was as high as $1.256 million USD in 2004. The Internet Crime Complaint Center has listed the above Nigerian internet scam as one of the ten major internet scams.Based on the latest report of Anti-Phishing Working Group (APWG) [8], there has been a 28% growth of Phishing scams in the past 4 months, mostly in the US and in Asia. Through social engineering and Trojans, it is very difficult for a common user to detect the infection.To avoid exploitation of your compassion, the following should be noted:(1)When you need to enter confidentialinformation, first make sure that theinformation is entered via an entirely secureand official webpage. There are two ways todetermine the security of the webpage:a.The address displayed on the browserbegins with https://, and not http://. Payattention to if the letter ‘s’ exists.b.There is a security lock sign on the lowerright corner of the webpage, and whenyour mouse points to the sign, a securitycertification sign shall appear.(2)Consider installing a browser security softwarelike SpoofStick which can detect fake websites.(3)If you suspect the received e-mail is a Phishinge-mail, do not open attachments attached to theemail. Opening an unknown attachment couldinstall malicious programs onto your computer.(4)Do not click on links attached to your emails. Itis always safer to visit the website through theofficial link or to first confirm the authenticityof the link. Never follow or click on suspiciouslinks in an e-mail. It is advisable to enter theURL at the address bar of the web browser,and not follow the given link.Generally speaking, Phishing [3] [5] is a method that exploits people’s sympathy in the form of aid-seeking e-mails; the e-mail act as bait. These e-mails usually request their readers to visit a link that seemingly links to some charitable organization’s website; but in truth links the readers to a website that will install a Trojan program into the reader’s computer. Therefore, users should not forward unauthenticated charity mails, or click on unfamiliar links in an e-mail. Sometimes, the link could be a very familiar link or an often frequented website, but still, it would be safer if you’d type in the address yourself so as to avoid being linked to a fraudulent website. Phisher deludes people by using similar e-mails mailed by well-known enterprises or banks; these e-mails often asks users to provide personal information, or result in losing their personal rights; they usually contain a counterfeit URL which links to a website where the users can fillin the required information. People are often trapped by phishing due to inattentionBesides, you must also be careful when using a search engine to search for donations and charitable organizations.2.3 Fake WebsitesFake bank websites stealing account numbers and passwords have become increasingly common with the growth of online financial transactions. Hence, when using online banking, we should take precautions like using a secure encrypted customer’s certificate, surf the net following the correct procedure, etc.There are countless kinds of phishing baits, for instance, messages that say data expired, data invalid, please update data, or identity verification intended to steal account ID and matching password. This typeof online scam is difficult for users to identify. As scam methods become finer, e-mails and forged websites created by the impostor resemble their original, and tremendous losses arise from the illegal transactions.The following are methods commonly used by fake websites. First, the scammers create a similar website homepage; then they send out e-mails withenticing messages to attract visitors. They may also use fake links to link internet surfers to their website. Next, the fake website tricks the visitors into entering their personal information, credit card information or online banking account number and passwords. After obtaining a user’s information, the scammers can use the information to drain the bank accounts, shop online or create fake credit cards and other similar crimes. Usually, there will be a quick search option on these fake websites, luring users to enter their account number and password. When a user enters their account number and password, the website will respond with a message stating that the server is under maintenance. Hence, we must observe the following when using online banking:(1)Observe the correct procedure for entering abanking website. Do not use links resultingfrom searches or links on other websites.(2)Online banking certifications are currently themost effective security safeguard measure. (3)Do not easily trust e-mails, phone calls, andshort messages, etc. that asks for your accountnumber and passwords.Phishers often impost a well-known enterprise while sending their e-mails, by changing the sender’s e-mail address to that of the well known enterprise, in order to gain people’s trust. The ‘From’ column of an e-mail is set by the mail software and can be easily changed by the web administrator. Then, the Phisher creates a fake information input website, and send out e-mails containing a link to this fake website to lure e-mail recipients into visiting his fake website.Most Phishers create imitations of well known enterprises websites to lure users into using their fake websites. Even so, a user can easily notice that the URL of the website they’re entering has no relation to the intended enterprise. Hence, Phishers may use different methods to impersonate enterprises and other people. A commonly used method is hiding the URL. This can easily be done with the help of JavaScript.Another way is to exploit the loopholes in an internet browser, for instance, displaying a fake URL in the browser’s address bar. The security loophole causing the address bar of a browser to display a fake URL is a commonly used trick and has often been used in the past. For example, an e-mail in HTML format may hold the URL of a website of a well-known enterprise, but in reality, the link connects to a fake website.The key to successfully use a URL similar to that of the intended website is to trick the visual senses. For example, the sender’s address could be disguised as that of Nikkei BP, and the link set to http://www.nikeibp.co.jp/ which has one k less than the correct URL which is http://www.nikkeibp.co.jp/. The two URLs look very similar, and the difference barely noticeable. Hence people are easily tricked into clicking the link.Besides the above, there are many more scams that exploit the trickery of visual senses. Therefore, you should not easily trust the given sender’s name and a website’s appearance. Never click on unfamiliar and suspicious URLs on a webpage. Also, never enter personal information into a website without careful scrutiny.3. ConclusionsBusiness strategy is the most effective form of defense and also the easiest to carry out. Therefore, they should be the first line of defense, and not last. First, determine if instant messaging is essential in the business; then weigh its pros and cons. Rules and norms must be set on user ends if it is decided that the business cannot do without instant messaging functionality. The end server should be able to support functions like centralized logging and encryption. If not, then strict rules must be drawn, and carried out by the users. Especially, business discussions must not be done over an instant messenger.The paper categorized hacking tricks into three categories: (1) Trojan programs that share files via instant messenger. (2) Phishing (3) Fake Websites. Hacking tricks when successfully carried out could cause considerable loss and damage to users. The first category of hacking tricks can be divided into three types: (1) Hijacking and Impersonation; (2) Denial of Service; (3) Information Disclosure.Acknowledgement:This work was supported by the National Science Council, Taiwan, under contract No. NSC 95-2221-E-029-024.References[1] B. Schneier, “The trojan horse race,”Communications of ACM, Vol. 42, 1999, pp.128.[2] C. L. Schuba, “Analysis of a denial of serviceattack on TCP,” IEEE Security and PrivacyConference, 1997, pp. 208-223.[3] E. Schultz, “Phishing is becoming moresophisticated,” Computer and Security, Vol.24(3), 2005, pp. 184-185.[4]G. Miklau, D. Suciu, “A formal analysis ofinformation disclosure in data exchange,”International Conference on Management ofData, 2004, pp. 575-586.[5]J. Hoyle, “'Phishing' for trouble,” Journal ofthe American Detal Association, Vol. 134(9),2003, pp. 1182-1182.[6]J. Scambray, S. McClure, G. Kurtz, Hackingexposed: network security secrets and solutions,McGraw-Hill, 2001.[7]T. Tsuji and A. Shimizu, “An impersonationattack on one-time password authenticationprotocol OSPA,” to appear in IEICE Trans.Commun, Vol. E86-B, No.7, 2003.[8]Anti-Phishing Working Group,.[9]/region/tw/enterprise/article/icq_threat.html.有关网络环境安全的黑客技术摘要：现在人们往往通过互联网处理事务。
毕业设计(论文)外文翻译
华南理工大学广州学院本科生毕业设计（论文）翻译外文原文名Agency Cost under the Restriction of Free Cash Flow中文译名自由现金流量的限制下的代理成本学院管理学院专业班级会计学3班学生姓名陈洁玉学生学号200930191100指导教师余勍讲师填写日期2015年5月11日外文原文版出处：译文成绩：指导教师（导师组长）签名：译文：自由现金流量的限制下的代理成本摘要代理成本理论是资本结构理论的一个重要分支。
自由现金流代理成本有显着的影响。
在这两个领域相结合的研究，将有助于建立和扩大理论体系。
代理成本理论基础上，本研究首先分类自由现金流以及统计方法的特点。
此外，投资自由现金流代理成本的存在证明了模型。
自由现金流代理成本理论引入限制，分析表明，它会改变代理成本，进而将影响代理成本和资本结构之间的关系，最后，都会影响到最优资本结构点，以保持平衡。
具体地说，自由现金流增加，相应地，债务比例会降低。
关键词：资本结构，现金流，代理成本，非金钱利益1、介绍代理成本理论，金融契约理论，信号模型和新的啄食顺序理论，新的资本结构理论的主要分支。
财务con-道的理论侧重于限制股东的合同行为，解决股东和债权人之间的冲突。
信令模式和新的啄食顺序理论中心解决投资者和管理者之间的冲突。
这两种类型的冲突是在商业组织中的主要冲突。
代理成本理论认为，如何达到平衡这两种类型的冲突，资本结构是如何形成的，这是比前两次在一定程度上更多的理论更全面。
……Agency Cost under the Restriction of Free Cash FlowAbstractAgency cost theory is an important branch of capital structural theory. Free cash flow has significant impact on agency cost. The combination of research on these two fields would help to build and extend the theoretical system. Based on agency cost theory, the present study firstly categorized the characteristics of free cash flow as well as the statistical methodologies. Furthermore, the existence of investing free cash flow in agency cost was proved by a model. Then free cash flow was introduced into agency cost theory as restriction, the analysis shows that it will change agency cost, in turn, will have an impact on the relationship between agency cost and capital structure, finally, will influence the optimal capital structure point to maintain the equilibrium. Concretely, with the increasing free cash flow, correspondingly, debt proportion will decrease.Keywords:Capital Structure,Free Cash Flow,Agency Cost,Non-Pecuniary Benefit1. IntroductionAgency cost theory, financial contract theory, signaling model and new pecking order theory are the main branches of new capital structure theory. Financial con-tract theory focuses on restricting stockholders’ behavior by contract and solving the conflict between stockholders and creditors. Signaling model and new pecking order theory center on solving the conflict between investors and managers. These two types of conflict are the main conflict in business organizations. Agency cost theory considers how equilibrium is reached in both types of conflict and how capital structure is formed, which is more theory is more comprehensive than the previous two to some degree.……。
毕业论文外文翻译范例
外文原文(一)Savigny and his Anglo-American Disciple s*M. H. HoeflichFriedrich Carl von Savigny, nobleman, law reformer, champion of the revived German professoriate, and founder of the Historical School of jurisprudence, not only helped to revolutionize the study of law and legal institutions in Germany and in other civil law countries, but also exercised a profound influence on many of the most creative jurists and legal scholars in England and the United States. Nevertheless, tracing the influence of an individual is always a difficult task. It is especially difficult as regards Savigny and the approach to law and legal sources propounded by the Historical School. This difficulty arises, in part, because Savigny was not alone in adopting this approach. Hugo, for instance, espoused quite similar ideas in Germany; George Long echoed many of these concepts in England during the 1850s, and, of course, Sir Henry Sumner Maine also espoused many of these same concepts central to historical jurisprudence in England in the 1860s and 1870s. Thus, when one looks at the doctrinal writings of British and American jurists and legal scholars in the period before 1875, it is often impossible to say with any certainty that a particular idea which sounds very much the sort of thing that might, indeed, have been derived from Savigny's works, was, in fact, so derived. It is possible, nevertheless, to trace much of the influence of Savigny and his legal writings in the United States and in Great Britain during this period with some certainty because so great was his fame and so great was the respect accorded to his published work that explicit references to him and to his work abound in the doctrinal writing of this period, as well as in actual law cases in the courts. Thus, Max Gutzwiller, in his classic study Der einfluss Savignys auf die Entwicklung des International privatrechts, was able to show how Savigny's ideas on conflict of laws influenced such English and American scholars as Story, Phillimore, Burge, and Dicey. Similarly, Andreas Schwarz, in his "Einflusse Deutscher Zivilistik im Auslande," briefly sketched Savigny's influence upon John Austin, Frederick Pollock, and James Bryce. In this article I wish to examine Savigny's influence over a broader spectrum and to draw a picture of his general fame and reputation both in Britain and in the United States as the leading Romanist, legal historian, and German legal academic of his day. The picture of this Anglo-American respect accorded to Savigny and the historical school of jurisprudence which emerges from these sources is fascinating. It sheds light not only upon Savigny’s trans-channel, trans-Atlantic fame, but also upon the extraordinarily*M.H.Hoeflich, Savigny and his Anglo-American Disciples, American Journal of Comparative Law, vol.37, No.1, 1989.cosmopolitan outlook of many of the leading American and English jurists of the time. Of course, when one sets out to trace the influence of a particular individual and his work, it is necessary to demonstrate, if possible, precisely how knowledge of the man and his work was transmitted. In the case of Savigny and his work on Roman law and ideas of historical jurisprudence, there were three principal modes of transmission. First, there was the direct influence he exercised through his contacts with American lawyers and scholars. Second, there was the influence he exercised through his books. Third, there was the influence he exerted indirectly through intermediate scholars and their works. Let us examine each mode separately.I.INFLUENCE OF THE TRANSLATED WORKSWhile American and British interest in German legal scholarship was high in the antebellum period, the number of American and English jurists who could read German fluently was relatively low. Even those who borrowed from the Germans, for instance, Joseph Story, most often had to depend upon translations. It is thus quite important that Savigny’s works were amongst the most frequently translated into English, both in the United States and in Great Britain. His most influential early work, the Vom Beruf unserer Zeitfur Rechtsgeschichte und Gestzgebung, was translated into English by Abraham Hayward and published in London in 1831. Two years earlier the first volume of his History of Roman Law in the Middle Ages was translated by Cathcart and published in Edinburgh. In 1830, as well, a French translation was published at Paris. Sir Erskine Perry's translation of Savigny's Treatise on Possession was published in London in 1848. This was followed by Archibald Brown's epitome of the treatise on possession in 1872 and Rattigan's translation of the second volume of the System as Jural Relations or the Law of Persons in 1884. Guthrie published a translation of the seventh volume of the System as Private International Law at Edinburgh in 1869. Indeed, two English translations were even published in the far flung corners of the British Raj. A translation of the first volume of the System was published by William Holloway at Madras in 1867 and the volume on possession was translated by Kelleher and published at Calcutta in 1888. Thus, the determined English-speaking scholar had ample access to Savigny's works throughout the nineteenth century.Equally important for the dissemination of Savigny's ideas were those books and articles published in English that explained and analyzed his works. A number of these must have played an important role in this process. One of the earliest of these is John Reddie's Historical Notices of the Roman law and of the Progress of its Study in Germany, published at Edinburgh in 1826. Reddie was a noted Scots jurist and held the Gottingen J.U.D. The book, significantly, is dedicated to Gustav Hugo. It is of that genre known as an external history of Roman law-not so much a history of substantive Roman legal doctrine but rather a historyof Roman legal institutions and of the study of Roman law from antiquity through the nineteenth century. It is very much a polemic for the study of Roman law and for the Historical School. It imparts to the reader the excitement of Savigny and his followers about the study of law historically and it is clear that no reader of the work could possibly be left unmoved. It is, in short, the first work of public relations in English on behalf of Savigny and his ideas.Having mentioned Reddie's promotion of Savigny and the Historical School, it is important to understand the level of excitement with which things Roman and especially Roman law were greeted during this period. Many of the finest American jurists were attracted-to use Peter Stein's term-to Roman and Civil law, but attracted in a way that, at times, seems to have been more enthusiastic than intellectual. Similarly, Roman and Civil law excited much interest in Great Britain, as illustrated by the distinctly Roman influence to be found in the work of John Austin. The attraction of Roman and Civil law can be illustrated and best understood, perhaps, in the context of the publicity and excitement in the English-speaking world surrounding the discovery of the only complete manuscript of the classical Roman jurist Gaius' Institutes in Italy in 1816 by the ancient historian and German consul at Rome, B.G. Niebuhr. Niebuhr, the greatest ancient historian of his time, turned to Savigny for help with the Gaius manuscript (indeed, it was Savigny who recognized the manuscript for what it was) and, almost immediately, the books and journals-not just law journals by any means-were filled with accounts of the discovery, its importance to legal historical studies, and, of course, what it said. For instance, the second volume of the American Jurist contains a long article on the civil law by the scholarly Boston lawyer and classicist, John Pickering. The first quarter of the article is a gushing account of the discovery and first publication of the Gaius manuscript and a paean to Niebuhr and Savigny for their role in this. Similarly, in an article published in the London Law Magazine in 1829 on the civil law, the author contemptuously refers to a certain professor who continued to tell his students that the text of Gaius' Institutes was lost for all time. What could better show his ignorance of all things legal and literary than to be unaware of Niebuhr's great discovery?Another example of this reaction to the discovery of the Gaius palimpsest is to be found in David Irving's Introduction to the Study of the Civil Law. This volume is also more a history of Roman legal scholarship and sources than a study of substantive Roman law. Its pages are filled with references to Savigny's Geschichte and its approach clearly reflects the influence of the Historical School. Indeed, Irving speaks of Savigny's work as "one of the most remarkable productions of the age." He must have been truly impressed with German scholarship and must also have been able to convince the Faculty of Advocates, forwhom he was librarian, of the worth of German scholarship, for in 1820 the Faculty sent him to Gottingen so that he might study their law libraries. Irving devotes several pages of his elementary textbook on Roman law to the praise of the "remarkable" discovery of the Gaius palimpsest. He traces the discovery of the text by Niebuhr and Savigny in language that would have befitted an adventure tale. He elaborates on the various labors required to produce a new edition of the text and was particularly impressed by the use of a then new chemical process to make the under text of the palimpsest visible. He speaks of the reception of the new text as being greeted with "ardor and exultation" strong words for those who spend their lives amidst the "musty tomes" of the Roman law.This excitement over the Verona Gaius is really rather strange. Much of the substance of the Gaius text was already known to legal historians and civil lawyers from its incorporation into Justinian's Institutes and so, from a substantive legal perspective, the find was not crucial. The Gaius did provide new information on Roman procedural rules and it did also provide additional information for those scholars attempting to reconstruct pre-Justinianic Roman law. Nevertheless, these contributions alone seem hardly able to justify the excitement the discovery caused. Instead, I think that the Verona Gaius discovery simply hit a chord in the literary and legal community much the same as did the discovery of the Rosetta Stone or of Schliemann’s Troy. Here was a monument of a great civilization brought newly to light and able to be read for the first time in millenia. And just as the Rosetta Stone helped to establish the modern discipline of Egyptology and Schliemann's discoveries assured the development of classical archaeology as a modern academic discipline, the discovery of the Verona Gaius added to the attraction Roman law held for scholars and for lawyers, even amongst those who were not Romanists by profession. Ancillary to this, the discovery and publication of the Gaius manuscript also added to the fame of the two principals involved in the discovery, Niebuhr and Savigny. What this meant in the English-speaking world is that even those who could not or did not wish to read Savigny's technical works knew of him as one of the discoverers of the Gaius text. This fame itself may well have helped in spreading Savigny's legal and philosophical ideas, for, I would suggest, the Gaius "connection" may well have disposed people to read other of Savigny's writings, unconnected to the Gaius, because they were already familiar with his name.Another example of an English-speaking promoter of Savigny is Luther Stearns Cushing, a noted Boston lawyer who lectured on Roman law at the Harvard Law School in 1848-49 and again in 1851- 1852.Cushing published his lectures at Boston in 1854 under the title An Introduction to the Study of Roman Law. He devoted a full chapter to a description of the historical school and to the controversy betweenSavigny and Thibaut over codification. While Cushing attempted to portray fairly the arguments of both sides, he left no doubt as to his preference for Savigny's approach:The labors of the historical school have established an entirely new and distinct era in the study of the Roman jurisprudence; and though these writers cannot be said to have thrown their predecessors into the shade, it seems to be generally admitted, that almost every branch of the Roman law has received some important modification at their hands, and that a knowledge of their writings, to some extent, at least, is essentially necessary to its acquisition.译文(一)萨维尼和他的英美信徒们*M·H·豪弗里奇弗雷德里奇·卡尔·冯·萨维尼出身贵族，是一位出色的法律改革家，也是一位倡导重建德国教授协会的拥护者，还是历史法学派的创建人之一。
毕业论文翻译英文原文和译文
毕业论文翻译英文原文和译文Failure Properties of Fractured Rock Masses as AnisotropicHomogenized MediaIntroductionIt is commonly acknowledged that rock masses always display discontinuous surfaces of various sizes and orientations usually referred to as fractures or joints Since the latter have much poorer mechanical characteristics than the rock material they play a decisive role in the overall behavior of rock structureswhose deformation as well as failure patterns are mainly governed by those of the joints It follows that from a geomechanical engineering standpoint design methods of structures involving jointed rock masses must absolutely account for such weakness surfaces in their analysisThe most straightforward way of dealing with this situation is to treat the jointed rock mass as an assemblage of pieces of intact rock material in mutual interaction through the separating joint interfaces Many design-oriented methods relating to this kind of approach have been developed in the past decades among themthe well-known block theory which attempts to identify poten-tially unstable lumps of rock from geometrical and kinematical considerations Goodman and Shi 1985 Warburton 1987 Goodman 1995 One should also quote the widely used distinct element method originating from the works of Cundall and coauthors Cundall and Strack 1979 Cundall 1988 which makes use of an explicit nite-difference numerical scheme for computing the displacements of the blocks considered as rigid or deformable bodies In this context attention is primarily focused on the formulation of realistic models for describing the joint behavior Since the previously mentioned direct approach is becoming highly complex and then numerically untractable as soon as a very large number of blocks is involved it seems advisable to look for alternative methods such as those derived from the concept of homogenization Actually such a concept is already partially conveyed in an empirical fashion by the famous Hoek and Browns criterion Hoek and Brown 1980 Hoek 1983 It stems from the intuitive idea that from a macroscopic point of view a rock mass intersected by a regular network of joint surfaces may be perceived as a homogeneous continuum Furthermore owing to the existence of joint preferential orientations one should expect such a homogenized material to exhibit anisotropic propertiesThe objective of the present paper is to derive a rigorous formulation for the failure criterion of a jointed rock mass as a homogenized medium from the knowledge of the joints and rock material respective criteriaIn the particular situation where twomutually orthogonal joint sets are considered a closed-form expression is obtained giving clear evidence of the related strength anisotropy A comparison is performed on an illustrative example between the results produced by the homogenization methodmaking use of the previously determined criterion and those obtained by means of a computer code based on the distinct element method It is shown that while both methods lead to almost identical results for a densely fractured rock mass a size or scale effect is observed in the case of a limited number of joints The second part of the paper is then devoted to proposing a method which attempts to capture such a scale effect while still taking advantage of a homogenization technique This is achieved by resorting to a micropolar or Cosserat continuum description of the fractured rock mass through the derivation of a generalized macroscopic failure condition expressed in terms of stresses and couple stresses The implementation of this model is nally illustrated on a simple example showing how it may actually account for such a scale effect Problem Statement and Principle of Homogenization ApproachThe problem under consideration is that of a foundation bridge pier or abutment resting upon a fractured bedrock Fig 1 whose bearing capacity needs to be evaluated from the knowledge of the strength capacities of the rock matrix and the joint interfaces The failure condition of the former will be expressed through the classicalMohr-Coulomb condition expressed by means of the cohesion and the friction angle Note that tensile stresses will be counted positive throughout the paperLikewise the joints will be modeled as plane interfaces represented by lines in the gures plane Their strength properties are described by means of a condition involving the stress vector of components στacting at any point of those interfacesAccording to the yield design or limit analysis reasoning the above structure will remain safe under a given vertical load Q force per unit length along the Oz axis if one can exhibit throughout the rock mass a stress distribution which satises the equilibrium equations along with the stress boundary conditionswhile complying with the strength requirement expressed at any point of the structureThis problem amounts to evaluating the ultimate load Q＋ beyond which failure will occur or equivalently within which its stability is ensured Due to the strong heterogeneity of the jointed rock mass insurmountable difculties are likely to arise when trying to implement the above reasoning directly As regards for instance the case where the strength properties of the joints are considerably lower than those of the rock matrix the implementation of a kinematic approach would require the use of failure mechanisms involving velocity jumps across the joints since the latter would constitute preferential zones for the occurrence offailure Indeed such a direct approach which is applied in most classical design methods is becoming rapidly complex as the density of joints increases that is as the typical joint spacing l is becoming small in comparison with a characteristic length of the structure such as the foundation width BIn such a situation the use of an alternative approach based on the idea of homogenization and related concept of macroscopic equivalent continuum for the jointed rock mass may be appropriate for dealing with such a problem More details about this theory applied in the context of reinforced soil and rock mechanics will be found in de Buhan et al 1989 de Buhan and Salenc on 1990 Bernaud et al 1995Macroscopic Failure Condition for Jointed Rock MassThe formulation of the macroscopic failure condition of a jointed rock mass may be obtained from the solution of an auxiliary yield design boundary-value problem attached to a unit representative cell of jointed rock Bekaert and Maghous 1996 Maghous et al1998 It will now be explicitly formulated in the particular situation of two mutually orthogonal sets of joints under plane strain conditions Referring to an orthonormal frame Owhose axes are placed along the joints directions and introducing the following change of stress variablessuch a macroscopic failure condition simply becomeswhere it will be assumed thatA convenient representation of the macroscopic criterion is to draw the strength envelope relating to an oriented facet of the homogenized material whose unit normal n I is inclined by an angle a with respect to the joint direction Denoting by and the normal and shear components of the stress vector acting upon such a facet it is possible to determine for any value of a the set of admissible stresses deduced from conditions 3 expressed in terms of The corresponding domain has been drawn in Fig 2 in the particular case whereTwo comments are worth being made1 The decrease in strength of a rock material due to the presence of joints is clearly illustrated by Fig2 The usual strength envelope corresponding to the rock matrix failure condition is truncated by two orthogonal semilines as soon as condition is fullled2 The macroscopic anisotropy is also quite apparent since for instance the strength envelope drawn in Fig 2 is dependent on the facet orientation a The usual notion of intrinsic curve should therefore be discarded but also the concepts of anisotropic cohesion and friction angle as tentatively introduced by Jaeger 1960 or Mc Lamore and Gray 1967 Nor can such an anisotropy be properly described by means of criteria based on an extension of the classical Mohr-Coulomb condition using the concept of anisotropy tensor Boehler and Sawczuk 1977 Nova 1980 Allirot and Bochler1981Application to Stability of Jointed Rock ExcavationThe closed-form expression 3 obtained for the macroscopic failure condition makes it then possible to perform the failure design of any structure built in such a material such as the excavation shown in Fig 3where h and βdenote the excavation height and the slope angle respectively Since no surcharge is applied to the structure the specic weight γof the constituent material will obviously constitute the sole loading parameter of the systemAssessing the stability of this structure will amount to evaluating the imum possible height h beyond which failure will occur A standard dimensional analysis of this problem shows that this critical height may be put in the formwhere θjoint orientation and K nondimensional factor governing the stability of the excavation Upper-bound estimates of this factor will now be determined by means of the yield design kinematic approach using two kinds of failure mechanisms shown in Fig 4Rotational Failure Mechanism [Fig 4 a ]The rst class of failure mechanisms considered in the analysis is a direct transposition of those usually employed for homogeneous and isotropic soil or rock slopes In such a mechanism a volume of homogenized jointed rock mass is rotating about a point Ω with an angular velocity ωThe curve separating this volume from the rest of the structure whichis kept motionless is a velocity jump line Since it is an arc of the log spiral of angle and focus Ω the velocity discontinuity at any point of this line is inclined at angle wm with respect to the tangent at the same pointThe work done by the external forces and the imum resisting work developed in such a mechanism may be written as see Chen and Liu 1990 Maghous et al 1998where and dimensionless functions and μ1 and μ2 angles specifying the position of the center of rotation ΩSince the kinematic approach of yield design states that a necessary condition for the structure to be stable writesit follows from Eqs 5 and 6 that the best upper-bound estimate derived from this rst class of mechanism is obtained by minimization with respect to μ1 and μ2which may be determined numericallyPiecewise Rigid-Block Failure Mechanism [Fig 4 b ]The second class of failure mechanisms involves two translating blocks of homogenized material It is dened by ve angular parameters In order to avoid any misinterpretation it should be specied that the terminology of block does not refer here to the lumps of rock matrix in the initial structure but merely means that in the framework of the yield design kinematic approach a wedge of homogenized jointed rock mass isgiven a virtual rigid-body motionThe implementation of the upper-bound kinematic approachmaking use of of this second class of failure mechanism leads to the following results where U represents the norm of the velocity of the lower block Hence the following upper-bound estimate for KResults and Comparison with Direct CalculationThe optimal bound has been computed numerically for the following set of parametersThe result obtained from the homogenization approach can then be compared with that derived from a direct calculation using the UDEC computer software Hart et al 1988 Since the latter can handle situations where the position of each individual joint is specied a series of calculations has been performed varying the number n of regularly spaced joints inclined at the same angleθ 10° with the horizontal and intersecting the facing of the excavation as sketched in Fig 5 The corresponding estimates of the stability factor have been plotted against n in the same gure It can be observed that these numerical estimates decrease with the number of intersecting joints down to the estimate produced by the homogenization approach The observed discrepancy between homogenization and direct approaches could be regarded as a size or scale effect which is not included in the classicalhomogenization model A possible way to overcome such a limitation ofthe latter while still taking advantage of the homogenization concept as a computational time-saving alternative for design purposes could be to resort to a description of the fractured rock medium as a Cosserat or micropolar continuum as advocated for instance by Biot 1967 Besdo 1985 Adhikary and Dyskin 1997 and Sulem and Mulhaus 1997 for stratied or block structures The second part of this paper is devoted to applying such a model to describing the failure properties of jointed rock media均质各向异性裂隙岩体的破坏特性概述由于岩体表面的裂隙或节理大小与倾向不同人们通常把岩体看做是非连续的尽管裂隙或节理表现出的力学性质要远远低于岩体本身但是它们在岩体结构性质方面起着重要的作用岩体本身的变形和破坏模式也主要是由这些节理所决定的从地质力学工程角度而言在涉及到节理岩体结构的设计方法中软弱表面是一个很重要的考虑因素解决这种问题最简单的方法就是把岩体看作是许多完整岩块的集合这些岩块之间有很多相交的节理面这种方法在过去的几十年中被设计者们广泛采用其中比较著名的是块体理论该理论试图从几何学和运动学的角度用来判别潜在的不稳定岩块Goodman 石根华 1985Warburton 1987Goodman 1995另外一种广泛使用的方法是特殊单元法它是由Cundall及其合作者Cundall Strack 1979 Cundall 1988提出来的其目的是用来求解显式有限差分数值问题计算刚性块体或柔性块体的位移本文的重点是阐述如何利用公式来描述实际的节理模型既然直接求解的方法很复杂数值分析方法也很难驾驭同时由于涉及到了数目如此之多的块体所以寻求利用均质化的方法是一个明智的选择事实上这个概念早在Hoek-Brown准则Hoek Brown 1980Hoek 1983得出的一个经验公式中就有所涉及它来自于宏观上的一个直觉被一个规则的表面节理网络所分割的岩体可以看做是一个均质的连续体由于节理倾向的不同这样的一个均质材料显示出了各向异性的性质本文的目的就是从节理和岩体各自准则出发推求出一个严格准确的公式来描述作为均匀介质的节理岩体的破坏准则先考查特殊情况从两组相互正交的节理着手得到一个封闭的表达式清楚的证明了强度的各向异性我们进行了一项试验把利用均质化方法得到的结果和以前普遍使用的准则得到的结果以及基于计算机编程的特殊单元法DEM得到的结果进行了对比结果表明对于密集裂隙的岩体结果基本一致对于节理数目较少的岩体存在一个尺寸效应或者称为比例效应本文的第二部分就是在保证均质化方法优点的前提下致力于提出一个新的方法来解决这种尺寸效应基于应力和应力耦合的宏观破坏条件提出利用微极模型或者Cosserat连续模型来描述节理岩体最后将会用一个简单的例子来演示如何应用这个模型来解决比例效应的问题问题的陈述和均质化方法的原理考虑这样一个问题一个基础桥墩或者其邻接处建立在一个有裂隙的岩床上Fig1岩床的承载能力通过岩基和节理交界面的强度估算出来岩基的破坏条件使用传统的莫尔-库伦条件可以用粘聚力C 1和内摩擦角 m 来表示本文中张应力采用正值计算同样用接触平面代替节理图示平面中用直线表示强度特性采用接触面上任意点的应力向量στ表示根据屈服设计或极限分析推断如果沿着应力边界条件岩体应力分布满足平衡方程和结构任意点的强度要求那么在一个给定的竖向荷载Q沿着OZ 轴方向作用下上部结构仍然安全这个问题可以归结为求解破坏发生处的极限承载力Q 或者是多大外力作用下结构能确保稳定由于节理岩体强度的各向异性若试图使用上述直接推求的方法难度就会增大很多比如由于节理强度特性远远低于岩基从运动学角度出发的方法要求考虑到破坏机理这就牵涉到了节理上的速度突跃而节理处将会是首先发生破坏的区域这种应用在大多数传统设计中的直接方法随着节理密度的增加越来越复杂确切地说这是因为相比较结构的长度如基础宽B而言典型节理间距L变得更小加大了问题的难度在这种情况下对节理岩体使用均质化方法和宏观等效连续的相关概念来处理可能就会比较妥当关于这个理论的更多细节在有关于加固岩土力学的文章中可以查到de Buhan等 1989de Buhan Salenc 1990Bernaud等 1995 节理岩体的宏观破坏条件节理岩体的宏观破坏条件公式可以从对节理岩体典型晶胞单元的辅助屈服设计边值问题中得到Bekaert Maghous 1996 Maghous等 1998现在可以精确地表示平面应变条件下两组相互正交节理的特殊情况建立沿节理方向的正交坐标系O 并引入下列应力变量宏观破坏条件可简化为其中假定宏观准则的一种简便表示方法是画出均质材料倾向面上的强度包络线其单位法线n的倾角α为节理的方向分别用σn 和τn 表示这个面上的正应力和切应力用表示条件3推求出一组许可应力σnτn 然后求解出倾角α当α≥ m 时相应的区域表示如图2所示并对此做出两个注解如下1 从图2中可以清楚的看出节理的存在导致了岩体强度的降低通常当时强度包络线和岩基破坏条件相一致其前半部分被两个正交的半条线切去2 宏观各向异性很显著比如图2中的强度包络线决定于方位角α应该抛弃固有曲线和各向异性粘聚力与摩擦角的概念其中后一个概念是由Jaeger1960或Mc Lamore Gray1967所引入的通过莫尔-库伦条件进行扩展利用各向异性张量的方法来描述各向异性也是不妥当的Boehler Sawczuk 1977 Nova 1980Allirot Bochler 1981在节理岩体开挖稳定性中的应用式3的封闭形式是从宏观破坏条件中得到的该式可以用来对此种材料的结构体进行破坏设计如图3所示的开挖h 和β分别表示开挖高度和边坡角由于结构上没有其他荷载材料比重γ就成为系统唯一的加载参数该结构的稳定性评价需要在破坏发生的部位算出最大可能高度 h通过标准量纲分析表明这个临界高度表示为其中θ为节理方位角K 为表示开挖部位稳定性的一个无量纲因子该因子的上界估计值可以分别使用图4所示的两种类型的破坏机制通过屈服设计的运动学方法来确定转动破坏机理 [Fig 4 a ]第一种类型的破坏机制通常把分析对象直接转换为均匀各向同性的岩坡或土坡若采用这种破坏机制各向同性的节理岩体围绕点Ω产生角速度为ω的旋转把静止的部分和运动的部分分开的曲线即为速度突跃线在这条角度为 m 圆心为Ω的滑弧上的任意一点上速度都不是连续的速度方向与该点处的切线成倾角 m在这种破坏机制下外力所做的功和最大抵抗功可以表示为下列形式Chen Liu 1990Maghous 等w e 和w mr为无量纲函数μ1 和μ2 为滑移体的圆心角由于屈服设计状态的动力学方法是结构稳固的一个必要条件故有联立5式和6式取μ1 和μ2 的最小值进行计算可以得到第一种类型破坏机制的最佳上界估计分段刚性块体破坏机理[Fig 4 b ]第二种类型的破坏机制涉及到了两种均匀材料块体的转换由五个角度参数定义为了避免误解应该具体指出块体并不是指代初始状态下的岩基块体在屈服设计运动学方法的框架下它代表的不仅仅这个意思一块均质节理岩体的运动可以近似看做是刚体运动对于第二种类型的破坏机制运用上界运动学方法可以得出以下结果在Fréard 2000 的文中可以找到详细的计算过程其中U 表示下盘块体的速度如图4-b所示因此K上界估计值为计算结果以及与直接计算结果之间的对比经过计算选定最优上界参数值为屈服时有利用UDEC软件Hart等 1988对均质化方法的计算结果和直接计算方法的结果进行对比发现当每一个节理的位置都已知时利用后一种方法就可以求解这个问题当节理间隙很规则且倾角保持在与水平成10 °的方向切割开挖平面时随着节理数n的变化计算出一系列的结果点绘于图5中与n相应的稳定性因子的估计值也在图5中表示出来容易看出随着分割节理数目的降低这些估计值的大小降低到了均质化方法的估计值均质化方法和直接计算法的差异可以看成是由于尺寸效应而引起的而均质化方法并没有尺寸效应的问题为了设计上计算的省时高效克服直接计算法的局限同时要运用均质化的概念考虑对裂隙岩体介质采用一种新的描述方法Cosserat 或者是微极连续Biot 1967 Besdo 1985 Adhikary Dyskin 1997 以及 Sulem Mulhaus 1997 对于分层岩体或者是块体结构都有所描述本文的第二部分就是致力于应用这个模型来描述节理岩体介质的破坏特性安徽理工大学毕业论文1。
毕业设计英文 翻译(原文)
编号：毕业设计(论文)外文翻译（原文）院（系）：桂林电子科技大学专业：电子信息工程学生姓名： xx学号： xxxxxxxxxxxxx 指导教师单位：桂林电子科技大学姓名： xxxx职称： xx2014年x月xx日Timing on and off power supplyusesThe switching power supply products are widely used in industrial automation and control, military equipment, scientific equipment, LED lighting, industrial equipment,communications equipment,electrical equipment,instrumentation, medical equipment, semiconductor cooling and heating, air purifiers, electronic refrigerator, LCD monitor, LED lighting, communications equipment, audio-visual products, security, computer chassis, digital products and equipment and other fields.IntroductionWith the rapid development of power electronics technology, power electronics equipment and people's work, the relationship of life become increasingly close, and electronic equipment without reliable power, into the 1980s, computer power and the full realization of the switching power supply, the first to complete the computer Power new generation to enter the switching power supply in the 1990s have entered into a variety of electronic, electrical devices, program-controlled switchboards, communications, electronic testing equipment power control equipment, power supply, etc. have been widely used in switching power supply, but also to promote the rapid development of the switching power supply technology .Switching power supply is the use of modern power electronics technology to control the ratio of the switching transistor to turn on and off to maintain a stable output voltage power supply, switching power supply is generally controlled by pulse width modulation (PWM) ICs and switching devices (MOSFET, BJT) composition. Switching power supply and linear power compared to both the cost and growth with the increase of output power, but the two different growth rates. A power point, linear power supply costs, but higher than the switching power supply. With the development of power electronics technology and innovation, making the switching power supply technology to continue to innovate, the turning points of this cost is increasingly move to the low output power side, the switching power supply provides a broad space for development.The direction of its development is the high-frequency switching power supply, high frequency switching power supply miniaturization, and switching power supply into a wider range of application areas, especially in high-tech fields, and promote the miniaturization of high-tech products, light of. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.classificationModern switching power supply, there are two: one is the DC switching power supply; the other is the AC switching power supply. Introduces only DC switching power supply and its function is poor power quality of the original eco-power (coarse) - such as mains power or battery power, converted to meet the equipment requirements of high-quality DC voltage (Varitronix) . The core of the DC switching power supply DC / DC converter. DC switching power supply classification is dependent on the classification of DC / DC converter. In other words, the classification of the classification of the DC switching power supply and DC/DC converter is the classification of essentially the same, the DC / DC converter is basically a classification of the DC switching power supply.DC /DC converter between the input and output electrical isolation can be divided into two categories: one is isolated called isolated DC/DC converter; the other is not isolated as non-isolated DC / DC converter.Isolated DC / DC converter can also be classified by the number of active power devices. The single tube of DC / DC converter Forward (Forward), Feedback (Feedback) two. The double-barreled double-barreled DC/ DC converter Forward (Double Transistor Forward Converter), twin-tube feedback (Double Transistor Feedback Converter), Push-Pull (Push the Pull Converter) and half-bridge (Half-Bridge Converter) four. Four DC / DC converter is the full-bridge DC / DC converter (Full-Bridge Converter).Non-isolated DC / DC converter, according to the number of active power devices can be divided into single-tube, double pipe, and four three categories. Single tube to a total of six of the DC / DC converter, step-down (Buck) DC / DC converter, step-up (Boost) DC / DC converters, DC / DC converter, boost buck (Buck Boost) device of Cuk the DC / DC converter, the Zeta DC / DC converter and SEPIC, the DC / DC converter. DC / DC converters, the Buck and Boost type DC / DC converter is the basic buck-boost of Cuk, Zeta, SEPIC, type DC / DC converter is derived from a single tube in this six. The twin-tube cascaded double-barreled boost (buck-boost) DC / DC converter DC / DC converter. Four DC / DC converter is used, the full-bridge DC / DC converter (Full-Bridge Converter).Isolated DC / DC converter input and output electrical isolation is usually transformer to achieve the function of the transformer has a transformer, so conducive to the expansion of the converter output range of applications, but also easy to achieve different voltage output , or a variety of the same voltage output.Power switch voltage and current rating, the converter's output power is usually proportional to the number of switch. The more the number of switch, the greater the output power of the DC / DC converter, four type than the two output power is twice as large,single-tube output power of only four 1/4.A combination of non-isolated converters and isolated converters can be a single converter does not have their own characteristics. Energy transmission points, one-way transmission and two-way transmission of two DC / DC converter. DC / DC converter with bi-directional transmission function, either side of the transmission power from the power of lateral load power from the load-lateral side of the transmission power.DC / DC converter can be divided into self-excited and separately controlled. With the positive feedback signal converter to switch to self-sustaining periodic switching converter, called self-excited converter, such as the the Luo Yeer (Royer,) converter is a typical push-pull self-oscillating converter. Controlled DC / DC converter switching device control signal is generated by specialized external control circuit.the switching power supply.People in the field of switching power supply technology side of the development of power electronic devices, while the development of the switching inverter technology, the two promote each other to promote the switching power supply annual growth rate of more than two digits toward the light, small, thin, low-noise, high reliability, the direction of development of anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, AC / AC DC / AC, such as inverters, DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardization, and has been recognized by the user, but AC / DC modular, its own characteristics make the modular process, encounter more complex technology and manufacturing process. Hereinafter to illustrate the structure and characteristics of the two types of switching power supply.Self-excited: no external signal source can be self-oscillation, completely self-excited to see it as feedback oscillation circuit of a transformer.Separate excitation: entirely dependent on external sustain oscillations, excited used widely in practical applications. According to the excitation signal structure classification; can be divided into pulse-width-modulated and pulse amplitude modulated two pulse width modulated control the width of the signal is frequency, pulse amplitude modulation control signal amplitude between the same effect are the oscillation frequency to maintain within a certain range to achieve the effect of voltage stability. The winding of the transformer can generally be divided into three types, one group is involved in the oscillation of the primary winding, a group of sustained oscillations in the feedback winding, there is a group of load winding. Such as Shanghai is used in household appliances art technological production of switching power supply, 220V AC bridge rectifier, changing to about 300V DC filter added tothe collector of the switch into the transformer for high frequency oscillation, the feedback winding feedback to the base to maintain the circuit oscillating load winding induction signal, the DC voltage by the rectifier, filter, regulator to provide power to the load. Load winding to provide power at the same time, take up the ability to voltage stability, the principle is the voltage output circuit connected to a voltage sampling device to monitor the output voltage changes, and timely feedback to the oscillator circuit to adjust the oscillation frequency, so as to achieve stable voltage purposes, in order to avoid the interference of the circuit, the feedback voltage back to the oscillator circuit with optocoupler isolation.technology developmentsThe high-frequency switching power supply is the direction of its development, high-frequency switching power supply miniaturization, and switching power supply into the broader field of application, especially in high-tech fields, and promote the development and advancement of the switching power supply, an annual more than two-digit growth rate toward the light, small, thin, low noise, high reliability, the direction of the anti-jamming. Switching power supply can be divided into AC / DC and DC / DC two categories, the DC / DC converter is now modular design technology and production processes at home and abroad have already matured and standardized, and has been recognized by the user, but modular AC / DC, because of its own characteristics makes the modular process, encounter more complex technology and manufacturing process. In addition, the development and application of the switching power supply in terms of energy conservation, resource conservation and environmental protection are of great significance.The switching power supply applications in power electronic devices as diodes, IGBT and MOSFET.SCR switching power supply input rectifier circuit and soft start circuit, a small amount of applications, the GTR drive difficult, low switching frequency, gradually replace the IGBT and MOSFET.Direction of development of the switching power supply is a high-frequency, high reliability, low power, low noise, jamming and modular. Small, thin, and the key technology is the high frequency switching power supply light, so foreign major switching power supply manufacturers have committed to synchronize the development of new intelligent components, in particular, is to improve the secondary rectifier loss, and the power of iron Oxygen materials to increase scientific and technological innovation in order to improve the magnetic properties of high frequency and large magnetic flux density (Bs), and capacitor miniaturization is a key technology. SMT technology allows the switching power supply has made considerable progress, the arrangement of the components in the circuit board on bothsides, to ensure that the light of the switching power supply, a small, thin. High-frequency switching power supply is bound to the traditional PWM switching technology innovation, realization of ZVS, ZCS soft-switching technology has become the mainstream technology of the switching power supply, and a substantial increase in the efficiency of the switching power supply. Indicators for high reliability, switching power supply manufacturers in the United States by reducing the operating current, reducing the junction temperature and other measures to reduce the stress of the device, greatly improve the reliability of products.Modularity is the overall trend of switching power supply, distributed power systems can be composed of modular power supply, can be designed to N +1 redundant power system, and the parallel capacity expansion. For this shortcoming of the switching power supply running noise, separate the pursuit of high frequency noise will also increase, while the use of part of the resonant converter circuit technology to achieve high frequency, in theory, but also reduce noise, but some The practical application of the resonant converter technology, there are still technical problems, it is still a lot of work in this field, so that the technology to be practical.Power electronics technology innovation, switching power supply industry has broad prospects for development. To accelerate the pace of development of the switching power supply industry in China, it must take the road of technological innovation, out of joint production and research development path with Chinese characteristics and contribute to the rapid development of China's national economy.Developments and trends of the switching power supply1955 U.S. Royer (Roger) invented the self-oscillating push-pull transistor single-transformer DC-DC converter is the beginning of the high-frequency conversion control circuit 1957 check race Jen, Sen, invented a self-oscillating push-pull dual transformers, 1964, U.S. scientists canceled frequency transformer in series the idea of switching power supply, the power supply to the size and weight of the decline in a fundamental way. 1969 increased due to the pressure of the high-power silicon transistor, diode reverse recovery time shortened and other components to improve, and finally made a 25-kHz switching power supply.At present, the switching power supply to the small, lightweight and high efficiency characteristics are widely used in a variety of computer-oriented terminal equipment, communications equipment, etc. Almost all electronic equipment is indispensable for a rapid development of today's electronic information industry power mode. Bipolar transistor made of 100kHz, 500kHz power MOS-FET made, though already the practical switching power supply is currently available on the market, but its frequency to be further improved. Toimprove the switching frequency, it is necessary to reduce the switching losses, and to reduce the switching losses, the need for high-speed switch components. However, the switching speed will be affected by the distribution of the charge stored in the inductance and capacitance, or diode circuit to produce a surge or noise. This will not only affect the surrounding electronic equipment, but also greatly reduce the reliability of the power supply itself. Which, in order to prevent the switching Kai - closed the voltage surge, RC or LC buffers can be used, and the current surge can be caused by the diode stored charge of amorphous and other core made of magnetic buffer . However, the high frequency more than 1MHz, the resonant circuit to make the switch on the voltage or current through the switch was a sine wave, which can reduce switching losses, but also to control the occurrence of surges. This switch is called the resonant switch. Of this switching power supply is active, you can, in theory, because in this way do not need to greatly improve the switching speed of the switching losses reduced to zero, and the noise is expected to become one of the high-frequency switching power supply The main ways. At present, many countries in the world are committed to several trillion Hz converter utility.the principle of IntroductionThe switching power supply of the process is quite easy to understand, linear power supplies, power transistors operating in the linear mode and linear power, the PWM switching power supply to the power transistor turns on and off state, in both states, on the power transistor V - security product is very small (conduction, low voltage, large current; shutdown, voltage, current) V oltammetric product / power device is power semiconductor devices on the loss.Compared with the linear power supply, the PWM switching power supply more efficient process is achieved by "chopping", that is cut into the amplitude of the input DC voltage equal to the input voltage amplitude of the pulse voltage. The pulse duty cycle is adjusted by the switching power supply controller. Once the input voltage is cut into the AC square wave, its amplitude through the transformer to raise or lower. Number of groups of output voltage can be increased by increasing the number of primary and secondary windings of the transformer. After the last AC waveform after the rectifier filter the DC output voltage.The main purpose of the controller is to maintain the stability of the output voltage, the course of their work is very similar to the linear form of the controller. That is the function blocks of the controller, the voltage reference and error amplifier can be designed the same as the linear regulator. Their difference lies in the error amplifier output (error voltage) in the drive before the power tube to go through a voltage / pulse-width conversion unit.Switching power supply There are two main ways of working: Forward transformand boost transformation. Although they are all part of the layout difference is small, but the course of their work vary greatly, have advantages in specific applications.the circuit schematicThe so-called switching power supply, as the name implies, is a door, a door power through a closed power to stop by, then what is the door, the switching power supply using SCR, some switch, these two component performance is similar, are relying on the base switch control pole (SCR), coupled with the pulse signal to complete the on and off, the pulse signal is half attentive to control the pole voltage increases, the switch or transistor conduction, the filter output voltage of 300V, 220V rectifier conduction, transmitted through the switching transformer secondary through the transformer to the voltage increase or decrease for each circuit work. Oscillation pulse of negative semi-attentive to the power regulator, base, or SCR control voltage lower than the original set voltage power regulator cut-off, 300V power is off, switch the transformer secondary no voltage, then each circuit The required operating voltage, depends on this secondary road rectifier filter capacitor discharge to maintain. Repeat the process until the next pulse cycle is a half weeks when the signal arrival. This switch transformer is called the high-frequency transformer, because the operating frequency is higher than the 50HZ low frequency. Then promote the pulse of the switch or SCR, which requires the oscillator circuit, we know, the transistor has a characteristic, is the base-emitter voltage is 0.65-0.7V is the zoom state, 0.7V These are the saturated hydraulic conductivity state-0.1V-0.3V in the oscillatory state, then the operating point after a good tune, to rely on the deep negative feedback to generate a negative pressure, so that the oscillating tube onset, the frequency of the oscillating tube capacitor charging and discharging of the length of time from the base to determine the oscillation frequency of the output pulse amplitude, and vice versa on the small, which determines the size of the output voltage of the power regulator. Transformer secondary output voltage regulator, usually switching transformer, single around a set of coils, the voltage at its upper end, as the reference voltage after the rectifier filter, then through the optocoupler, this benchmark voltage return to the base of the oscillating tube pole to adjust the level of the oscillation frequency, if the transformer secondary voltage is increased, the sampling coil output voltage increases, the positive feedback voltage obtained through the optocoupler is also increased, this voltage is applied oscillating tube base, so that oscillation frequency is reduced, played a stable secondary output voltage stability, too small do not have to go into detail, nor it is necessary to understand the fine, such a high-power voltage transformer by switching transmission, separated and after the class returned by sampling the voltage from the opto-coupler pass separated after class, so before the mains voltage, and after the classseparation, which is called cold plate, it is safe, transformers before power is independent, which is called switching power supply.the DC / DC conversionDC / DC converter is a fixed DC voltage transformation into a variable DC voltage, also known as the DC chopper. There are two ways of working chopper, one Ts constant pulse width modulation mode, change the ton (General), the second is the frequency modulation, the same ton to change the Ts, (easy to produce interference). Circuit by the following categories:Buck circuit - the step-down chopper, the average output voltage U0 is less than the input voltage Ui, the same polarity.Boost Circuit - step-up chopper, the average output voltage switching power supply schematic U0 is greater than the input voltage Ui, the same polarity.Buck-Boost circuit - buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, the inductance transmission.Cuk circuit - a buck or boost chopper, the output average voltage U0 is greater than or less than the input voltage Ui, the opposite polarity, capacitance transmission.The above-mentioned non-isolated circuit, the isolation circuit forward circuits, feedback circuit, the half-bridge circuit, the full bridge circuit, push-pull circuit. Today's soft-switching technology makes a qualitative leap in the DC / DC the U.S. VICOR company design and manufacture a variety of ECI soft-switching DC / DC converter, the maximum output power 300W, 600W, 800W, etc., the corresponding power density (6.2 , 10,17) W/cm3 efficiency (80-90)%. A the Japanese Nemic Lambda latest using soft-switching technology, high frequency switching power supply module RM Series, its switching frequency (200 to 300) kHz, power density has reached 27W/cm3 with synchronous rectifier (MOSFETs instead of Schottky diodes ), so that the whole circuit efficiency by up to 90%.AC / DC conversionAC / DC conversion will transform AC to DC, the power flow can be bi-directional power flow by the power flow to load known as the "rectification", referred to as "active inverter power flow returned by the load power. AC / DC converter input 50/60Hz AC due must be rectified, filtered, so the volume is relatively large filter capacitor is essential, while experiencing safety standards (such as UL, CCEE, etc.) and EMC Directive restrictions (such as IEC, FCC, CSA) in the AC input side must be added to the EMC filter and use meets the safety standards of the components, thus limiting the miniaturization of the volume of AC / DC power, In addition, due to internal frequency, high voltage, current switching, making the problem difficult to solve EMC also high demands on the internal high-density mountingcircuit design, for the same reason, the high voltage, high current switch makes power supply loss increases, limiting the AC / DC converter modular process, and therefore must be used to power system optimal design method to make it work efficiency to reach a certain level of satisfaction.AC / DC conversion circuit wiring can be divided into half-wave circuit, full-wave circuit. Press the power phase can be divided into single-phase three-phase, multiphase. Can be divided into a quadrant, two quadrant, three quadrants, four-quadrant circuit work quadrant.he selection of the switching power supplySwitching power supply input on the anti-jamming performance, compared to its circuit structure characteristics (multi-level series), the input disturbances, such as surge voltage is difficult to pass on the stability of the output voltage of the technical indicators and linear power have greater advantages, the output voltage stability up to (0.5)%. Switching power supply module as an integrated power electronic devices should be selected。
土木工程毕业论文中英文翻译
外文翻译班级：xxx学号：xxx姓名：xxx一、外文原文：Structural Systems to resist lateral loads Commonly Used structural SystemsWith loads measured in tens of thousands kips, there is little room in the design of high-rise buildings for excessively complex thoughts. Indeed, the better high-rise buildings carry the universal traits of simplicity of thought and clarity of expression.It does not follow that there is no room for grand thoughts. Indeed, it is with such grand thoughts that the new family of high-rise buildings has evolved. Perhaps more important, the new concepts of but a few years ago have become commonplace in today’ s technology.Omitting some concepts that are related strictly to the materials of construction, the most commonly used structural systems used in high-rise buildings can be categorized as follows:1.Moment-resisting frames.2.Braced frames, including eccentrically braced frames.3.Shear walls, including steel plate shear walls.4.Tube-in-tube structures.5.Core-interactive structures.6.Cellular or bundled-tube systems.Particularly with the recent trend toward more complex forms, but in response also to the need for increased stiffness to resist the forces from wind and earthquake, most high-rise buildings have structural systems built up of combinations of frames, braced bents, shear walls, and related systems. Further, for the taller buildings, the majorities are composed of interactive elements in three-dimensional arrays.The method of combining these elements is the very essence of the design process for high-rise buildings. These combinations need evolve in response to environmental, functional, and cost considerations so as to provide efficient structures that provoke the architectural development to new heights. This is not to say that imaginative structural design can create great architecture. To the contrary, many examples of fine architecture have been created with only moderate support from the structural engineer, while only fine structure, not great architecture, can be developed without the genius and the leadership of a talented architect. In any event, the best of both is needed to formulate a truly extraordinary design of a high-rise building.While comprehensive discussions of these seven systems are generally available in the literature, further discussion is warranted here .The essence of the design process is distributed throughout the discussion.Moment-Resisting FramesPerhaps the most commonly used system in low-to medium-rise buildings, the moment-resisting frame, is characterized by linear horizontal and vertical members connected essentially rigidly at their joints. Such frames are used as a stand-alone system or in combination with other systems so as to provide the needed resistance to horizontal loads. In the taller of high-rise buildings, the system is likely to be found inappropriate for a stand-alone system, this because of the difficulty in mobilizing sufficient stiffness under lateral forces.Analysis can be accomplished by STRESS, STRUDL, or a host of other appropriate computer programs; analysis by the so-called portal method of the cantilever method has no place in today’s technology.Because of the intrinsic flexibility of the column/girder intersection, and because preliminary designs should aim to highlight weaknesses of systems, it is not unusual to use center-to-center dimensions for the frame in the preliminary analysis. Of course, in the latter phases of design, a realistic appraisal in-joint deformation is essential.Braced Frame sThe braced frame, intrinsically stiffer than the moment –resisting frame, finds also greater application to higher-rise buildings. The system is characterized by linear horizontal, vertical, and diagonal members, connected simply or rigidly at their joints. It is used commonly inconjunction with other systems for taller buildings and as a stand-alone system in low-to medium-rise buildings.While the use of structural steel in braced frames is common, concrete frames are more likely to be of the larger-scale variety.Of special interest in areas of high seismicity is the use of the eccentric braced frame.Again, analysis can be by STRESS, STRUDL, or any one of a series of two –or three dimensional analysis computer programs. And again, center-to-center dimensions are used commonly in the preliminary analysis. Shear wallsThe shear wall is yet another step forward along a progression of ever-stiffer structural systems. The system is characterized by relatively thin, generally but not always concrete elements that provide both structural strength and separation between building functions.In high-rise buildings, shear wall systems tend to have a relatively high aspect ratio, that is, their height tends to be large compared to their width. Lacking tension in the foundation system, any structural element is limited in its ability to resist overturning moment by the width of the system and by the gravity load supported by the element. Limited to a narrow overturning, One obvious use of the system, which does have the needed width, is in the exterior walls of building, where the requirement for windows is kept small.Structural steel shear walls, generally stiffened against buckling by a concrete overlay, have found application where shear loads are high. The system, intrinsically more economical than steel bracing, is particularly effective in carrying shear loads down through the taller floors in the areas immediately above grade. The system has the further advantage of having high ductility a feature of particular importance in areas of high seismicity.The analysis of shear wall systems is made complex because of the inevitable presence of large openings through these walls. Preliminary analysis can be by truss-analogy, by the finite element method, or by making use of a proprietary computer program designed to consider the interaction, or coupling, of shear walls.Framed or Braced TubesThe concept of the framed or braced or braced tube erupted into the technology with the IBM Building in Pittsburgh, but was followed immediately with the twin 110-story towers of the World Trade Center, New York and a number of other buildings .The system is characterized by three –dimensional frames, braced frames, or shear walls, forming a closed surface more or less cylindrical in nature, but of nearly any plan configuration. Because those columns that resist lateral forces are placed as far as possible from the cancroids of the system, the overall moment of inertia is increased and stiffness is very high.The analysis of tubular structures is done using three-dimensional concepts, or by two- dimensional analogy, where possible, whichever method is used, it must be capable of accounting for the effects of shear lag.The presence of shear lag, detected first in aircraft structures, is a serious limitation in the stiffness of framed tubes. The concept has limited recent applications of framed tubes to the shear of 60 stories. Designers have developed various techniques for reducing the effects of shear lag, most noticeably the use of belt trusses. This system finds application in buildings perhaps 40stories and higher. However, except for possible aesthetic considerations, belt trusses interfere with nearly every building function associated with the outside wall; the trusses are placed often at mechanical floors, mush to the disapproval of the designers of the mechanical systems. Nevertheless, as a cost-effective structural system, the belt truss works well and will likely find continued approval from designers. Numerous studies have sought to optimize the location of these trusses, with the optimum location very dependent on the number of trusses provided. Experience would indicate, however, that the location of these trusses is provided by the optimization of mechanical systems and by aesthetic considerations, as the economics of the structural system is not highly sensitive to belt truss location.Tube-in-Tube StructuresThe tubular framing system mobilizes every column in the exterior wallin resisting over-turning and shearing forces. The term‘tube-in-tube’is largely self-explanatory in that a second ring of columns, the ring surrounding the central service core of the building, is used as an inner framed or braced tube. The purpose of the second tube is to increase resistance to over turning and to increase lateral stiffness. The tubes need not be of the same character; that is, one tube could be framed, while the other could be braced.In considering this system, is important to understand clearly the difference between the shear and the flexural components of deflection, the terms being taken from beam analogy. In a framed tube, the shear component of deflection is associated with the bending deformation of columns and girders , the webs of the framed tube while the flexural component is associated with the axial shortening and lengthening of columns , the flanges of the framed tube. In a braced tube, the shear component of deflection is associated with the axial deformation of diagonals while the flexural component of deflection is associated with the axial shortening and lengthening of columns.Following beam analogy, if plane surfaces remain plane , the floor slabs,then axial stresses in the columns of the outer tube, being farther form the neutral axis, will be substantially larger than the axial stresses in the inner tube. However, in the tube-in-tube design, when optimized, the axial stresses in the inner ring of columns may be as high, or evenhigher, than the axial stresses in the outer ring. This seeming anomaly is associated with differences in the shearing component of stiffness between the two systems. This is easiest to under-stand where the inner tube is conceived as a braced , shear-stiff tube while the outer tube is conceived as a framed , shear-flexible tube.Core Interactive StructuresCore interactive structures are a special case of a tube-in-tube wherein the two tubes are coupled together with some form of three-dimensional space frame. Indeed, the system is used often wherein the shear stiffness of the outer tube is zero. The United States Steel Building, Pittsburgh, illustrates the system very well. Here, the inner tube is a braced frame, the outer tube has no shear stiffness, and the two systems are coupled if they were considered as systems passing in a straight line from the “hat” structure. Note that the exterior columns would be improperly modeled if they were considered as systems passing in a straight line from the “hat” to the foundations; these columns are perhaps 15% stiffer as they follow the elastic curve of the braced core. Note also that the axial forces associated with the lateral forces in the inner columns change from tension to compression over the height of the tube, with the inflection point at about 5/8 of the height of the tube. The outer columns, of course, carry the same axial force under lateral load for the full height of the columns because the columns because the shearstiffness of the system is close to zero.The space structures of outrigger girders or trusses, that connect the inner tube to the outer tube, are located often at several levels in the building. The AT&T headquarters is an example of an astonishing array of interactive elements:1.The structural system is 94 ft wide, 196ft long, and 601ft high.2.Two inner tubes are provided, each 31ft by 40 ft , centered 90 ft apartin the long direction of the building.3.The inner tubes are braced in the short direction, but with zero shearstiffness in the long direction.4.A single outer tube is supplied, which encircles the buildingperimeter.5.The outer tube is a moment-resisting frame, but with zero shearstiffness for the center50ft of each of the long sides.6.A space-truss hat structure is provided at the top of the building.7.A similar space truss is located near the bottom of the building8.The entire assembly is laterally supported at the base on twinsteel-plate tubes, because the shear stiffness of the outer tube goes to zero at the base of the building.Cellular structuresA classic example of a cellular structure is the Sears Tower, Chicago,a bundled tube structure of nine separate tubes. While the Sears Towercontains nine nearly identical tubes, the basic structural system has special application for buildings of irregular shape, as the several tubes need not be similar in plan shape, It is not uncommon that some of the individual tubes one of the strengths and one of the weaknesses of the system.This special weakness of this system, particularly in framed tubes, has to do with the concept of differential column shortening. The shortening of a column under load is given by the expression△=ΣfL/EFor buildings of 12 ft floor-to-floor distances and an average compressive stress of 15 ksi 138MPa, the shortening of a column under load is 15 1212/29,000 or per story. At 50 stories, the column will have shortened to in. 94mm less than its unstressed length. Where one cell of a bundled tube system is, say, 50stories high and an adjacent cell is, say, 100stories high, those columns near the boundary between .the two systems need to have this differential deflection reconciled.Major structural work has been found to be needed at such locations. In at least one building, the Rialto Project, Melbourne, the structural engineer found it necessary to vertically pre-stress the lower height columns so as to reconcile the differential deflections of columns in close proximity with the post-tensioning of the shorter column simulatingthe weight to be added on to adjacent, higher columns.二、原文翻译：抗侧向荷载的结构体系常用的结构体系若已测出荷载量达数千万磅重,那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了;确实,较好的高层建筑普遍具有构思简单、表现明晰的特点;这并不是说没有进行宏观构思的余地;实际上,正是因为有了这种宏观的构思,新奇的高层建筑体系才得以发展,可能更重要的是：几年以前才出现的一些新概念在今天的技术中已经变得平常了;如果忽略一些与建筑材料密切相关的概念不谈,高层建筑里最为常用的结构体系便可分为如下几类：1．抗弯矩框架;2．支撑框架,包括偏心支撑框架;3．剪力墙,包括钢板剪力墙;4．筒中框架;5．筒中筒结构;6．核心交互结构;7．框格体系或束筒体系;特别是由于最近趋向于更复杂的建筑形式,同时也需要增加刚度以抵抗几力和地震力,大多数高层建筑都具有由框架、支撑构架、剪力墙和相关体系相结合而构成的体系;而且,就较高的建筑物而言,大多数都是由交互式构件组成三维陈列;将这些构件结合起来的方法正是高层建筑设计方法的本质;其结合方式需要在考虑环境、功能和费用后再发展,以便提供促使建筑发展达到新高度的有效结构;这并不是说富于想象力的结构设计就能够创造出伟大建筑;正相反,有许多例优美的建筑仅得到结构工程师适当的支持就被创造出来了,然而,如果没有天赋甚厚的建筑师的创造力的指导,那么,得以发展的就只能是好的结构,并非是伟大的建筑;无论如何,要想创造出高层建筑真正非凡的设计,两者都需要最好的;虽然在文献中通常可以见到有关这七种体系的全面性讨论,但是在这里还值得进一步讨论;设计方法的本质贯穿于整个讨论;设计方法的本质贯穿于整个讨论中;抗弯矩框架抗弯矩框架也许是低,中高度的建筑中常用的体系,它具有线性水平构件和垂直构件在接头处基本刚接之特点;这种框架用作独立的体系,或者和其他体系结合起来使用,以便提供所需要水平荷载抵抗力;对于较高的高层建筑,可能会发现该本系不宜作为独立体系,这是因为在侧向力的作用下难以调动足够的刚度;我们可以利用STRESS,STRUDL 或者其他大量合适的计算机程序进行结构分析;所谓的门架法分析或悬臂法分析在当今的技术中无一席之地,由于柱梁节点固有柔性,并且由于初步设计应该力求突出体系的弱点,所以在初析中使用框架的中心距尺寸设计是司空惯的;当然,在设计的后期阶段,实际地评价结点的变形很有必要;支撑框架支撑框架实际上刚度比抗弯矩框架强,在高层建筑中也得到更广泛的应用;这种体系以其结点处铰接或则接的线性水平构件、垂直构件和斜撑构件而具特色,它通常与其他体系共同用于较高的建筑,并且作为一种独立的体系用在低、中高度的建筑中;尤其引人关注的是,在强震区使用偏心支撑框架;此外,可以利用STRESS,STRUDL,或一系列二维或三维计算机分析程序中的任何一种进行结构分析;另外,初步分析中常用中心距尺寸;剪力墙剪力墙在加强结构体系刚性的发展过程中又前进了一步;该体系的特点是具有相当薄的,通常是而不总是混凝土的构件,这种构件既可提供结构强度,又可提供建筑物功能上的分隔;在高层建筑中,剪力墙体系趋向于具有相对大的高宽经,即与宽度相比,其高度偏大;由于基础体系缺少应力,任何一种结构构件抗倾覆弯矩的能力都受到体系的宽度和构件承受的重力荷载的限制;由于剪力墙宽度狭狭窄受限,所以需要以某种方式加以扩大,以便提从所需的抗倾覆能力;在窗户需要量小的建筑物外墙中明显地使用了这种确有所需要宽度的体系;钢结构剪力墙通常由混凝土覆盖层来加强以抵抗失稳,这在剪切荷载大的地方已得到应用;这种体系实际上比钢支撑经济,对于使剪切荷载由位于地面正上方区域内比较高的楼层向下移特别有效;这种体系还具有高延性之优点,这种特性在强震区特别重要;由于这些墙内必然出同一些大孔,使得剪力墙体系分析变得错综复杂;可以通过桁架模似法、有限元法,或者通过利用为考虑剪力墙的交互作用或扭转功能设计的专门计处机程序进行初步分析框架或支撑式筒体结构：框架或支撑式筒体最先应用于IBM公司在Pittsburgh的一幢办公楼,随后立即被应用于纽约双子座的110层世界贸易中心摩天大楼和其他的建筑中;这种系统有以下几个显着的特征：三维结构、支撑式结构、或由剪力墙形成的一个性质上差不多是圆柱体的闭合曲面,但又有任意的平面构成;由于这些抵抗侧向荷载的柱子差不多都被设置在整个系统的中心,所以整体的惯性得到提高,刚度也是很大的;在可能的情况下,通过三维概念的应用、二维的类比,我们可以进行筒体结构的分析;不管应用那种方法,都必须考虑剪力滞后的影响;这种最先在航天器结构中研究的剪力滞后出现后,对筒体结构的刚度是一个很大的限制;这种观念已经影响了筒体结构在60层以上建筑中的应用;设计者已经开发出了很多的技术,用以减小剪力滞后的影响,这其中最有名的是桁架的应用;框架或支撑式筒体在40层或稍高的建筑中找到了自己的用武之地;除了一些美观的考虑外,桁架几乎很少涉及与外墙联系的每个建筑功能,而悬索一般设置在机械的地板上,这就令机械体系设计师们很不赞成;但是,作为一个性价比较好的结构体系,桁架能充分发挥它的性能,所以它会得到设计师们持续的支持;由于其最佳位置正取决于所提供的桁架的数量,因此很多研究已经试图完善这些构件的位置;实验表明：由于这种结构体系的经济性并不十分受桁架位置的影响,所以这些桁架的位置主要取决于机械系统的完善,审美的要求,筒中筒结构：筒体结构系统能使外墙中的柱具有灵活性,用以抵抗颠覆和剪切力;“筒中筒”这个名字顾名思义就是在建筑物的核心承重部分又被包围了第二层的一系列柱子,它们被当作是框架和支撑筒来使用;配置第二层柱的目的是增强抗颠覆能力和增大侧移刚度;这些筒体不是同样的功能,也就是说,有些筒体是结构的,而有些筒体是用来支撑的;在考虑这种筒体时,清楚的认识和区别变形的剪切和弯曲分量是很重要的,这源于对梁的对比分析;在结构筒中,剪切构件的偏角和柱、纵梁例如：结构筒中的网等的弯曲有关,同时,弯曲构件的偏角取决于柱子的轴心压缩和延伸例如：结构筒的边缘等;在支撑筒中,剪切构件的偏角和对角线的轴心变形有关,而弯曲构件的偏角则与柱子的轴心压缩和延伸有关;根据梁的对比分析,如果平面保持原形例如：厚楼板,那么外层筒中柱的轴心压力就会与中心筒柱的轴心压力相差甚远,而且稳定的大于中心筒;但是在筒中筒结构的设计中,当发展到极限时,内部轴心压力会很高的,甚至远远大于外部的柱子;这种反常的现象是由于两种体系中的剪切构件的刚度不同;这很容易去理解,内筒可以看成是一个支撑或者说是剪切刚性的筒,而外筒可以看成是一个结构或者说是剪切弹性的筒;核心交互式结构：核心交互式结构属于两个筒与某些形式的三维空间框架相配合的筒中筒特殊情况;事实上,这种体系常用于那种外筒剪切刚度为零的结构;位于Pittsburgh的美国钢铁大楼证实了这种体系是能很好的工作的;在核心交互式结构中,内筒是一个支撑结构,外筒没有任何剪切刚度,而且两种结构体系能通过一个空间结构或“帽”式结构共同起作用;需要指出的是,如果把外部的柱子看成是一种从“帽”到基础的直线体系,这将是不合适的；根据支撑核心的弹性曲线,这些柱子只发挥了刚度的15%;同样需要指出的是,内柱中与侧向力有关的轴向力沿筒高度由拉力变为压力,同时变化点位于筒高度的约5/8处;当然,外柱也传递相同的轴向力,这种轴向力低于作用在整个柱子高度的侧向荷载,因为这个体系的剪切刚度接近于零;把内外筒相连接的空间结构、悬臂梁或桁架经常遵照一些规范来布置;美国电话电报总局就是一个布置交互式构件的生动例子;1、结构体系长米,宽米,高米;2、布置了两个筒,每个筒的尺寸是米×米,在长方向上有米的间隔;3、在短方向上内筒被支撑起来,但是在长方向上没有剪切刚度;4、环绕着建筑物布置了一个外筒;5、外筒是一个瞬时抵抗结构,但是在每个长方向的中心米都没有剪切刚度;6、在建筑的顶部布置了一个空间桁架构成的“帽式”结构;7、在建筑的底部布置了一个相似的空间桁架结构;8、由于外筒的剪切刚度在建筑的底部接近零,整个建筑基本上由两个钢板筒来支持;框格体系或束筒体系结构：位于美国芝加哥的西尔斯大厦是箱式结构的经典之作,它由九个相互独立的筒组成的一个集中筒;由于西尔斯大厦包括九个几乎垂直的筒,而且筒在平面上无须相似,基本的结构体系在不规则形状的建筑中得到特别的应用;一些单个的筒高于建筑一点或很多是很常见的;事实上,这种体系的重要特征就在于它既有坚固的一面,也有脆弱的一面;这种体系的脆弱,特别是在结构筒中,与柱子的压缩变形有很大的关系,柱子的压缩变形有下式计算：△=ΣfL/E对于那些层高为米左右和平均压力为138MPa的建筑,在荷载作用下每层柱子的压缩变形为1512/29000或毫米;在第50层柱子会压缩94毫米,小于它未受压的长度;这些柱子在50层的时候和100层的时候的变形是不一样的,位于这两种体系之间接近于边缘的那些柱需要使这种不均匀的变形得以调解;主要的结构工作都集中在布置中;在Melbourne的Rialto项目中,结构工程师发现至少有一幢建筑,很有必要垂直预压低高度的柱子,以便使柱不均匀的变形差得以调解,调解的方法近似于后拉伸法,即较短的柱转移重量到较高的邻柱上;。
本科毕业设计(论文)英文翻译模板
本科毕业设计（论文）英文翻译论文标题(中文)学院******姓名***专业*******班级**********大气探测2班学号*************** 大气探测、信处、两个专业填写电子信息工程。
生物医学工程、电子信息科学与技术、雷电防护科学与技术As its name implies, region growing is a procedure that groups pixels or subregions into larger regions based on predefined criteria. The basic approach is to start with a set of “seed ” points and from these grow regions by appending to each seed those gray level or color).be used to assignpixels to regions during the centroid of these clusters can be used as seeds.… … …左右手共面波导的建模与带通滤波器设计速发展之势，而它的出现却是源于上世纪本研究提出了一种新型混合左右手（CPW ）的独特功能。
目前这种有效电长度为0°的新型混合左右手共面波导（CRLH CPW ）谐振器正在兴起，这种谐振器工作在5GHz 时的体积比常规结构的谐振器缩减小49.1%。
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大学毕业论文英文翻译中文译文计算机网络每个一个世纪都有一种主导地位的技术。
18世纪伴随着工业革命的到来的是大型机械系统的时代；19世纪是蒸汽机的时代，而20世纪的发展历程中，关键的技术是信息收集、处理和分发。
在其他的发展方面，我们还可以看到：遍布全球的电话网络的建立起来了，无线电广播和电视的出现了，计算机工业诞生了，并且以超乎想象的速度在成长；另外通信卫星也发射上天了。
技术的快速发展的一个直接结果是，这些领域正在快速地融合，信息收集、传输、存储和处理之间的差别正在迅速地消失。
对于具有数百个办公室的大型组织来说，尽管这些办公室分布在广阔的地理区域中，但未来期望的情景是，工作人员只要单击一下按钮，就可以查看最远处分部的状态。
随着信息收集、处理和分发能力的不断提高，我们对于更加复杂的信息处理技术的需求也增长得更快。
与其他的工业(比如汽车和航空运输业)相比，计算机工业还是非常年轻，尽管如此，计算机技术却在很短的时间内有了惊人的进展。
在计算机诞生之初的20年间，计算机系统是高度集中化的，通常位于一个很大的房间中。
该房间通常配有玻璃墙，参观的人透过玻璃墙可以欣赏到里边伟大的电子奇迹。
中等规模的公司或者大学可能会有一台或者两台计算机，而大型的研究机构最多也就几十台计算机。
要在20年内生产出大量同样功能但是体积比邮票还小的计算机，在当时的人们看来纯属科学幻想。
计算机和通信的结合对于计算机系统的组织方式产生了深远的影响。
把一台大型的计算机放在一个单独的房间中，然后用户带着他们的处理任务去房间里上机，这种"计算机中心"的概念现在已经完全过时了。
由一台计算机来处理整个组织中所有的计算需求，这种老式的模型已经被新的模型所取代，在新的模型下，由大量独立的，但相互连接起来的计算机来共同完成计算任务。
这些系统称为计算机网络(computer networks)。
如何设计这些网络，并且将这些网络组织起来，这就是本书的主题。
在本书中，我们将使用术语"计算机网络"来表示通过同一种技术相互连接起来的一组自主计算机的集合。
如果两台计算机能够交换信息，则称这两台计算机相互连接的(interconnected)。
两台机器之间的连接不一定通过铜线，光纤，微波，红外线和通信卫星也可以用来建立连接。
以后我们将会看到，网络可以有不同的大小，形状和形式。
Internet或者万维网(World Wide Wed)都不是计算机网，可能有很多人对此觉得很奇怪。
到本书的结尾的时候，你就会明白其中的原因。
现在给出一个简单的答案：Internet并不是一个单一的网络，而是一个有许多个网络构成的网络，Web是一个分布式系统，它运行在Internet之上。
在一些文献中，计算机网络和分布式系统(distributed system)这两个概念容易使人混淆。
两者的关键差别在于；在一个分布式系统中，一组独立的计算机展现给用户的是一个统一的整体，就好像是一个系统似的。
通常，对用户来说，分布式系统只有一个模型或范型。
在操作系统之上有一层中间件(middleware)负责实现这个模型。
一个著名的分布式系统的例子是万维网(World Wide Web),在万维网中，所有的一切看起来就好像是一个文档(Web页面)一样。
在计算机网络中，这种统一性，模型以及其中的软件都不存在。
用户看到的是实际的机器。
计算机网络并没有使这些机器看起来是统一的，或者使它们的行为是统一的。
如果这些机器有不同的硬件或者操作系统，那么，这些差异对于用户来说都是完全可见的。
如果有一个用户希望在一台远程机器上运行一个程序，那么他必须登陆到远程机器上，然后在那台机器上运行该程序。
实际上分布式系统是建立在网络之上的软件系统。
正是因为软件的特性，所以分布式系统具有高度的内敛性和透明性。
因此，网络与分布式系统之间的区别更多地在于软件(特别是操作系统)，而不是硬件。
然而，这两个主题之间也有许多重合的地方。
例如，分布式系统和计算机网络都需要移动文件。
不同之处在于是谁来发起移动操作，是系统还是用户?虽然本书的焦点主要是在于网络，但是讨论到的许多话题在分布式系统中也是很重要的。
1.计算机网络的应用在开始讨论技术细节在前，首先值得画一点时间来说明为什么人们对于计算机网络很感兴趣，以及计算机网络可以用来做什么事情。
毕竟，如果没有人对计算机网络感兴趣的话，那就不会建立这么多的计算机网络了。
我们首先讨论针对公司和个人的传统用法，然后再转移到最新的一些发展动向，包括针对移动用户和家庭网络的应用上来。
2.商业应用许多公司都具有相当数量的计算机。
例如，一家公司可能用一些单独的计算机来监视生产过程，记录库存，以及管理工资的发放工作。
最初的时候，这些计算机都是独立工作的，但是后来管理部门决定将这些计算机连接起来，以便将有关整个公司的信息关联起俩，并且可以随时访问这些信息。
将这个公司的情形更加范化一点，这里涉及到的问题是资源共享(resource sharing),其目标是，让每一个人都可以访问所有的程序，设备和特殊的数据，并且做到跟这些资源和用户的物理位置无关。
一个既显然又非常普通的例子是让一个办公室的所有工作人员共同一台打印机。
公司没有必要为每一个工作人员都配备一台个人打印机，而且，一台高性能的网络打印机通常比一大批独立的打印机更加便宜，打印速度更快，而且也容易维护。
然而，比共享物理资源(比如打印机，扫描仪和CD刻录机)更重要的是共享信息。
每一个大型的或中等规模的公司和许多小型的公司都越来越依赖于计算机化的信息。
大多数公司都有顾客记录，库存信息，收到的账单记录，财务报告，缴税信息以及其他更多的在线信息，如果一家银行的所有计算机都不能工作了，那么这家银行可能坚持不到5分钟。
如果一个现代化的生产车间使用了计算机控制的装配线，那么计算机崩溃后也不可能继续工作。
现在即使是很小规模的旅行社，甚至只有三个人规模的律师事务所也与计算机网络有着密切的联系，通过计算机网络，雇员可以即时地访问有关的信息和文档。
对于小公司而言，可能所有的计算机都在一个办公室里，或者位于同一个建筑物内，但是对于大型的公司，计算机和雇员们可能分散在许许多多个办公室中，甚至分散在不同的国家的多个分支机构中，然而，纽约的一个销售员有时需要访问新加坡的产品库存数据库。
换句话说，一个用户离他访问的数据库相隔15000公里，但是他仍然要访问这些数据，就好像这些数据存放在本地一样。
简而言之，计算机网络的这个目标可以定义为：企图打破"地理位置的束缚(tyranny of geography)"。
安装最简单的形式，你可以把一个公司的信息系统想象成：有一个或者句多个数据库，以及许多需要远程访问这些数据库地雇员们组成的。
在这个模型中，数据存储在性能强大的计算机上，称为服务器(server)。
通常这些服务器集中在同一个场所。
并且由系统管理员对它们进行维护。
相反，雇员们的桌子上有一些件的机器，称为客户(client)，通过这些客户，雇员可以访问远程的数据，例如他们可以访问远程的电子表格，(有时候，我们也把客户机器的使用称作"客户"，但是根据上下文环境，你应该可以判断出到底是指机器，还是指机器的用户。
)客户和服务器通过网络连接起来，如图1.1所示,请注意，这里我们只是用一个简单的椭圆形来表示一个网络，而没有表达其中的任何细节，当我们从抽象意义上来表达一个网络的时候，就使用这种形式。
当有需要的时候，我们也会提供更多的细节。
这个结构称为"客户-服务器模型(client-server model)"。
这种模型有很多广泛的应用，它也是许多网络应用的基础。
当客户和服务器位于同一个建筑物内(比如，属于同一个公司)的时候，这种模型是最适用的；当客户和服务器相隔很远的时候，这种模型也是适用的。
例如，当一个人在家里访问一个Web页面的时候，就使用了这种模型；其中，远程地Web服务器就是模型中的服务器。
用户的个人计算机是模型中的客户。
在大多数情况下，一台服务器可以处理许多客户的请求。
如果更加仔细的看一看客户-服务器模型，我们就可以看到，该模型涉及到了两个进程，一个位于客户机器上的，另一个位于服务器上。
其中的通信形式是这样的：客户进程通过网络将一个消息发送给服务器进程。
然后客户进程等待应答消息。
当服务器进程获得了请求消息之后，它执行所请求的工作，或者查到客户所要的数据，然后送回一个应答消息。
3.显示了这些信息。
建立计算机网络的第二个目标是为了满足人的需要，而不是信息或者计算机的要求。
计算机网络可以为雇员们提供一个功能强大的通信媒介(communication medium)。
现在，几乎每一家公司，只要有两台以上的计算机，就会有一个电子邮件(electronic mail E-mail)系统，雇员们利用该系统来进行大量的日常的通信。
实际上，这样带来的一个问题是，每个人每天必须处理大量的E-mail，而且，其中有一些E-mail是没有意义的。
因为公司的老板发现，他们只需点一下按钮就可以将同样的E-mail消息(通常并没有多少实际内容)发送给所有部下。
但是E-mail并不是计算机网络带来的唯一的一种新型的通信形式。
有了网络之后，两个或者多个相距甚远的人可以联合起来写一份报告，这是非常容易做到的。
当一个工作人员修改了一份在线文档的时候，其他的人立即就可以看到文档被改动了，根本不用为一封信而等上几天。
这样的速度使得那些分散在各地的工作组协同工作非常容易，而这在以前是根本不可能的。
另一种计算机辅助通信的形式是视频会议。
利用这项技术，即使雇员们处于相距甚远的不同地点上，他们也可以开会，相互之间看得到，听得到，甚至还可以在一个共享的虚拟黑板上写写画画。
视频会议是一个功能强大的工具。
它消除了以前的差旅开销和路途上所需的时间。
有时候你可能会听到这样的说法，通信和运输在进行一场竞争，不管哪一方赢了，都会淘汰掉另一方。
第三个目标是，越来越多的公司与其它公司进行电子商务活动，特别是跟供应商和客户公司之间的商务活动。
例如，汽车，飞机和计算机的制造商需要从各种不同的供应商购买子系统，然后再将这些部件装配起来。
这些制造商利用计算机网络，就可以根据需要以电子的方式下订单。
这种实时(即根据需要)下订单的能力大大降低了对于大库存量的需求，并且也提高了效率。
第四个目标正在变得越来越重要，那就是通过Internet与客户做各种交易。
航空公司，书店和音乐零售商发现，许多顾客喜欢在家里购买他们的商品或者服务。
因此，许多公司提供了在线查询商品和服务的功能，并且允许在线下订单。
计算机网络的这种用途有望在将来得到进一步的发展。