翻译文献图片
收藏知乎网友总结的23种英文文献翻译软件,助力文献阅读
01搜狗翻译搜狗翻译的文档翻译功能有三个优点：第一，可以直接上传文档，流程操作简单化，这才是一键翻译哇，我之前只能说是很多键……；第二，在线阅读翻译结果时，系统可实时提供原文与译文的双屏对照，方便对比查看；第三，译文可直接免费下载，方便进一步研读或分享。
02Google Chrome浏览器假设一个情景，你想在PubMed上找到以清华大学为第一单位的施一公教授的文章，那么，可以在Chrome浏览器上，登上PubMed，搜索格式为Yigong Shi Tsinghua University，即可找到其发表的文章。
接着，看上一篇蛮不错的，点击进去看看，然后，还是全英文。
这时候，你可以试下Chrome自带的网页翻译，真的可以秒翻译，将英文翻译为中文，而且还可以快速转换中/英界面。
03Adobe Acrobat笔者在这里给大伙介绍另一款秒翻译PDF文档的神器（笔者使用的Adobe Acrobat Pro DC，至于具体的下载和安装方式，读者可自行百度）。
但是，需要注意一点，这是Adobe Acrobat，而不是Adobe Reader。
在这里，请应许笔者介绍下开发出Adobe Acrobat的公司——Adobe。
Adobe，在软件界绝对是巨头中巨头的存在。
打个比方，我们常用的PS、PR、AE、In、LR等，无一例外都是领域中的顶尖水平，而且都是Adobe家的。
其中，Adobe家中就有一款几位出色的PDF编辑及处理软件——Adobe Acrobat。
（据说PDF作为国际通用的文件存储格式，也是依它而起）OK，进入主题，Adobe Acrobat是长这个样子的。
它可能干嘛呢？PDF 转word、图片合拼为PDF、编辑PDF等等，可以说，与PDF相关的，它都可以搞定。
那如何使用它来帮助我们翻译文献PDF呢？第一步，用它打开文献PDF文件；第二步，点击使用界面上的“文件”，接着点击“另存为”，选择存储格式为“HTML”，如下图；第三步，PDF文档在导出完成后，会得到两个文件，一是将PDF转为HTML格式的网页文件，另一个则是支持网页文件里面的图片（若删，网页里面的图片显示不出来）第四步，找到网页文件，打开方式选择Google Chrome浏览器，接着，结合Chrome浏览器的网页翻译，即可秒翻。
英文文献翻译
外文文献原稿和译文原稿Sodium Polyacrylate:Also known as super-absorbent or “SAP”(super absorbent polymer), Kimberly Clark used to call it SAM (super absorbent material). It is typically used in fine granular form (like table salt). It helps improve capacity for better retention in a disposable diaper, allowing the product to be thinner with improved performance and less usage of pine fluff pulp. The molecular structure of the polyacrylate has sodium carboxylate groups hanging off the main chain. When it comes in contact with water, the sodium detaches itself, leaving only carboxylions. Being negatively charged, these ions repel one another so that the polymer also has cross-links, which effectively leads to a three-dimensional structure. It has hige molecular weight of more than a million; thus, instead of getting dissolved, it solidifies into a gel. The Hydrogen in the water (H-O-H) is trapped by the acrylate due to the atomic bonds associated with the polarity forces between the atoms. Electrolytes in the liquid, such as salt minerals (urine contains 0.9% of minerals), reduce polarity, thereby affecting superabsorbent properties, especially with regard to the superabsorbent capacity for liquid retention. This is the main reason why diapers containing SAP should never be tested with plain water. Linear molecular configurations have less total capacity than non-linear molecules but, on the other hand, retention of liquid in a linear molecule is higher than in a non-linear molecule, due to improved polarity. For a list of SAP suppliers, please use this link: SAP, the superabsorbent can be designed to absorb higher amounts of liquids (with less retention) or very high retentions (but lower capacity). In addition, a surface cross linker can be added to the superabsorbent particle to help it move liquids while it is saturated. This helps avoid formation of "gel blocks", the phenomenon that describes the impossibility of moving liquids once a SAP particle gets saturated.History of Super Absorbent Polymer ChemistryUn til the 1980’s, water absorbing materials were cellulosic or fiber-based products. Choices were tissue paper, cotton, sponge, and fluff pulp. The water retention capacity of these types of materials is only 20 times their weight – at most.In the early 1960s, the United States Department of Agriculture (USDA) was conducting work on materials to improve water conservation in soils. They developed a resin based on the grafting of acrylonitrile polymer onto the backbone of starch molecules (i.e. starch-grafting). The hydrolyzed product of the hydrolysis of this starch-acrylonitrile co-polymer gave water absorption greater than 400 times its weight. Also, the gel did not release liquid water the way that fiber-based absorbents do.The polymer came to be known as “Super Slurper”.The USDA gave the technical know how several USA companies for further development of the basic technology. A wide range of grating combinations were attempted including work with acrylic acid, acrylamide and polyvinyl alcohol (PVA).Since Japanese companies were excluded by the USDA, they started independent research using starch, carboxy methyl cellulose (CMC), acrylic acid, polyvinyl alcohol (PVA) and isobutylene maleic anhydride (IMA).Early global participants in the development of super absorbent chemistry included Dow Chemical, Hercules, General Mills Chemical, DuPont, National Starch & Chemical, Enka (Akzo), Sanyo Chemical, Sumitomo Chemical, Kao, Nihon Starch and Japan Exlan.In the early 1970s, super absorbent polymer was used commercially for the first time –not for soil amendment applications as originally intended –but for disposable hygienic products. The first product markets were feminine sanitary napkins and adult incontinence products.In 1978, Park Davis (d.b.a. Professional Medical Products) used super absorbent polymers in sanitary napkins.Super absorbent polymer was first used in Europe in a baby diaper in 1982 when Schickendanz and Beghin-Say added the material to the absorbent core. Shortly thereafter, UniCharm introduced super absorbent baby diapers in Japan while Proctor & Gamble and Kimberly-Clark in the USA began to use the material.The development of super absorbent technology and performance has been largely led by demands in the disposable hygiene segment. Strides in absorption performance have allowed the development of the ultra-thin baby diaper which uses a fraction of the materials – particularly fluff pulp – which earlier disposable diapers consumed.Over the years, technology has progressed so that there is little if any starch-grafted super absorbent polymer used in disposable hygienic products. These super absorbents typically are cross-linked acrylic homo-polymers (usually Sodium neutralized).Super absorbents used in soil amendments applications tend to be cross-linked acrylic-acrylamide co-polymers (usually Potassium neutralized).Besides granular super absorbent polymers, ARCO Chemical developed a super absorbent fiber technology in the early 1990s. This technology was eventually sold to Camelot Absorbents. There are super absorbent fibers commercially available today. While significantly more expensive than the granular polymers, the super absorbent fibers offer technical advantages in certain niche markets including cable wrap, medical devices and food packaging.Sodium polyacrylate, also known as waterlock, is a polymer with the chemical formula [-CH2-CH(COONa)-]n widely used in consumer products. It has the ability to absorb as much as 200 to 300 times its mass in water. Acrylate polymers generally are considered to possess an anionic charge. While sodium neutralized polyacrylates are the most common form used in industry, there are also other salts available including potassium, lithium and ammonium.ApplicationsAcrylates and acrylic chemistry have a wide variety of industrial uses that include: ∙Sequestering agents in detergents. (By binding hard water elements such as calcium and magnesium, the surfactants in detergents work more efficiently.) ∙Thickening agents∙Coatings∙Fake snowSuper absorbent polymers. These cross-linked acrylic polymers are referred to as "Super Absorbents" and "Water Crystals", and are used in baby diapers. Copolymerversions are used in agriculture and other specialty absorbent applications. The origins of super absorbent polymer chemistry trace back to the early 1960s when the U.S. Department of Agriculture developed the first super absorbent polymer materials. This chemical is featured in the Maximum Absorbency Garment used by NASA.译文聚丙烯酸钠聚丙烯酸钠，又可以称为超级吸收剂或者又叫高吸水性树脂，凯博利克拉克教授曾经称它为SAM即：超级吸收性物质。
外文文献翻译(图片版)
本科毕业论文外文参考文献译文及原文学院经济与贸易学院专业经济学（贸易方向）年级班别2007级 1 班学号3207004154学生姓名欧阳倩指导教师童雪晖2010 年 6 月 3 日目录1 外文文献译文（一）中国银行业的改革和盈利能力（第1、2、4部分） (1)2 外文文献原文（一）CHINA’S BANKING REFORM AND PROFITABILITY（Part 1、2、4） (9)1概述世界银行（1997年）曾声称，中国的金融业是其经济的软肋。
当一国的经济增长的可持续性岌岌可危的时候，金融业的改革一直被认为是提高资金使用效率和消费型经济增长重新走向平衡的必要（Lardy，1998年，Prasad，2007年）。
事实上，不久前，中国的国有银行被视为“技术上破产”，它们的生存需要依靠充裕的国家流动资金。
但是，在银行改革开展以来，最近，强劲的盈利能力已恢复到国有商业银行的水平。
但自从中国的国有银行在不久之前已经走上了改革的道路，它可能过早宣布银行业的改革尚未取得完全的胜利。
此外，其坚实的财务表现虽然强劲，但不可持续增长。
随着经济增长在2008年全球经济衰退得带动下已经开始软化，银行预计将在一个比以前更加困难的经济形势下探索。
本文的目的不是要评价银行业改革对银行业绩的影响，这在一个完整的信贷周期后更好解决。
相反，我们的目标是通过审查改革的进展和银行改革战略，并分析其近期改革后的强劲的财务表现，但是这不能完全从迄今所进行的改革努力分离。
本文有三个部分。
在第二节中，我们回顾了中国的大型国有银行改革的战略，以及其执行情况，这是中国银行业改革的主要目标。
第三节中分析了2007年的财务表现集中在那些在市场上拥有浮动股份的四大国有商业银行：中国工商银行（工商银行），中国建设银行（建行），对中国银行（中银）和交通银行（交通银行）。
引人注目的是中国农业银行，它仍然处于重组上市过程中得适当时候的后期。
第四节总结一个对银行绩效评估。
翻译文献（1）（1）
翻译文献（1）（1）费兰德斯和荷兰水体中的优先有机污染物和用纳滤膜去除的可行性的评估摘要有机微污染物在地下水和地表水中的发现已经成为饮用水工业非常关注的问题，主要由于其可能的健康影响，由于这些污染物的极性，导致它们用传统的水处理栅栏无法完全去除，这篇论文综述了优先有机微污染物及它们在费兰德斯和荷兰的水体中的出现，此外，用纳滤膜去除的废弃物是对筛选优先微污染的定性预测，这个定性的预测是依据重要的溶质和纳滤膜参数，然后将预测值与文献中获得的实验值进行比较。
总之，定性地预测值与文献值大致相同，依据关键参数的预测可能因此被证明是一个在饮用水厂设计中评估纳滤膜的实施作为有机微污染的处理步骤的快速而有用的技术。
简介在上几个世纪，饮用水工业一直非常关注有机微污染物在饮用水中的出现，在二十世纪八十年代，荷兰和费兰德斯饮用水公司面临着地表水中的不断提高的杀虫剂的浓度问题，一个双轨办法可解决这个问题：政府对农民和生产者施加的压力是开发杀虫剂的替代物，饮用水问题通过实施活性炭吸附得到改善，在二十世纪九十年代，更精确的分析方法和更高的产量以及这些污染物再度侵入环境使其它有机微污染物也得到关注，尤其是内分泌干扰化合物，因为它们对人体与动物内分泌系统会产生负面影响。
对于多种化合物，世界卫生组织与美国环保局已经对人类安全饮水浓度发布指引，为了在水龙头提供安全的饮用水，研究新兴的微量污染物的去除，使其浓度低于健康限制浓度是必要的，特别是极微量的污染物往往在目前的饮用水过程中难以去除。
压力驱动膜过程，如纳滤膜（NF）和反渗透（RO）可能被证明是去除有机微污染物的一项有趣的技术。
然而，虽然观察到大多数有机微污染物有相对较高的废弃值，但多种污染物仍然可以在纳滤膜NF/ 反渗透RO装置中发现。
本文的目的是双重的，包括准备了有机微污染物的优先级列表（特别是佛兰德斯/荷兰的情况，但也是普遍适用的）。
其次用NF去除这些优先控制污染物的可能性进行评估，这一评估将为将预测排斥反应值比作实验测定的文献值提供更多的理论基础。
英文文献全文翻译
英文文献全文翻译全文共四篇示例，供读者参考第一篇示例：LeGuin, Ursula K. (December 18, 2002). "Dancing at the Edge of the World: Thoughts on Words, Women, Places".《世界边缘的舞蹈：关于语言、女性和地方的思考》Introduction:In "Dancing at the Edge of the World," Ursula K. LeGuin explores the intersection of language, women, and places. She writes about the power of words, the role of women in society, and the importance of our connection to the places we inhabit. Through a series of essays, LeGuin invites readers to think critically about these topics and consider how they shape our understanding of the world.Chapter 1: LanguageConclusion:第二篇示例：IntroductionEnglish literature translation is an important field in the study of language and culture. The translation of English literature involves not only the linguistic translation of words or sentences but also the transfer of cultural meaning and emotional resonance. This article will discuss the challenges and techniques of translating English literature, as well as the importance of preserving the original author's voice and style in the translated text.Challenges in translating English literature第三篇示例：Title: The Importance of Translation of Full English TextsTranslation plays a crucial role in bringing different languages and cultures together. More specifically, translating full English texts into different languages allows for access to valuable information and insights that may otherwise be inaccessible to those who do not speak English. In this article, we will explore the importance of translating full English texts and the benefits it brings.第四篇示例：Abstract: This article discusses the importance of translating English literature and the challenges translators face when putting together a full-text translation. It highlights the skills and knowledge needed to accurately convey the meaning and tone of the original text while preserving its cultural and literary nuances. Through a detailed analysis of the translation process, this article emphasizes the crucial role translators play in bridging the gap between languages and making English literature accessible to a global audience.IntroductionEnglish literature is a rich and diverse field encompassing a wide range of genres, styles, and themes. From classic works by Shakespeare and Dickens to contemporary novels by authors like J.K. Rowling and Philip Pullman, English literature offers something for everyone. However, for non-English speakers, accessing and understanding these works can be a challenge. This is where translation comes in.Translation is the process of rendering a text from one language into another, while striving to preserve the original meaning, tone, and style of the original work. Translating afull-length English text requires a deep understanding of both languages, as well as a keen awareness of the cultural andhistorical context in which the work was written. Additionally, translators must possess strong writing skills in order to convey the beauty and complexity of the original text in a new language.Challenges of Full-text TranslationTranslating a full-length English text poses several challenges for translators. One of the most significant challenges is capturing the nuances and subtleties of the original work. English literature is known for its rich and layered language, with intricate wordplay, metaphors, and symbolism that can be difficult to convey in another language. Translators must carefully consider each word and phrase in order to accurately convey the author's intended meaning.Another challenge of full-text translation is maintaining the author's unique voice and style. Each writer has a distinct way of expressing themselves, and a good translator must be able to replicate this voice in the translated text. This requires a deep understanding of the author's writing style, as well as the ability to adapt it to the conventions of the target language.Additionally, translators must be mindful of the cultural and historical context of the original work. English literature is deeply rooted in the history and traditions of the English-speaking world, and translators must be aware of these influences in orderto accurately convey the author's intended message. This requires thorough research and a nuanced understanding of the social, political, and economic factors that shaped the work.Skills and Knowledge RequiredTo successfully translate a full-length English text, translators must possess a wide range of skills and knowledge. First and foremost, translators must be fluent in both the source language (English) and the target language. This includes a strong grasp of grammar, syntax, and vocabulary in both languages, as well as an understanding of the cultural and historical context of the works being translated.Translators must also have a keen eye for detail and a meticulous approach to their work. Every word, sentence, and paragraph must be carefully considered and translated with precision in order to accurately convey the meaning of the original text. This requires strong analytical skills and a deep understanding of the nuances and complexities of language.Furthermore, translators must possess strong writing skills in order to craft a compelling and engaging translation. Translating a full-length English text is not simply a matter of substituting one word for another; it requires creativity, imagination, and a deep appreciation for the beauty of language. Translators mustbe able to capture the rhythm, cadence, and tone of the original work in their translation, while also adapting it to the conventions of the target language.ConclusionIn conclusion, translating a full-length English text is a complex and challenging task that requires a high level of skill, knowledge, and creativity. Translators must possess a deep understanding of both the source and target languages, as well as the cultural and historical context of the work being translated. Through their careful and meticulous work, translators play a crucial role in making English literature accessible to a global audience, bridging the gap between languages and cultures. By preserving the beauty and complexity of the original text in their translations, translators enrich our understanding of literature and bring the works of English authors to readers around the world.。
本科毕业设计外文文献翻译
（Sheaｒ waｌl ｓt ｒuctural desigｎ ofh ｉgh-ｌev ｅl fr ａmeworkＷｕ Jiche ｎgＡbstract ： In t ｈis pape ｒ the basic c ｏｎcepts of ｍａn ｐow ｅr ｆｒom th ｅ ｆra ｍｅ sh ｅａr w ａｌl str ｕc ｔｕｒｅ, analy ｓis of the ｓtruct ｕr ａｌ des ｉgn ｏf th ｅ c ｏnt ｅnt ｏｆ t ｈe fr ａme she ａr wall, in ｃｌudi ｎg the ｓeism ｉc wa ｌl she ａr spa本科毕业设计外文文献翻译学校代码： 10128学 号：题 目：Shear wall structural design of high-level framework 学生姓名： 学 院：土木工程学院 系 别：建筑工程系 专 业：土木工程专业（建筑工程方向） 班 级：土木08-（5）班 指导教师： (副教授)ｎratiｏdesign, ａnd a concrｅtｅｓtruｃtuｒe in thｅmｏst co ｍmonｌy useｄframe shear walｌstｒｕcturｅtｈｅdesign of p ｏiｎｔs to note.Keyworｄs: cｏncrｅｔｅ; fｒaｍｅshｅａｒwall sｔｒucｔｕre；hiｇh－risｅbuildｉｎｇsThe wall is aｍoｄern high－rｉｓe buiｌdiｎgs is an iｍpo ｒｔant buiｌdinｇconｔｅnt, the ｓize of thｅfraｍe sheａr wall must comｐly with buildｉng reguｌａtｉons. The pｒｉnｃipｌe is ｔhat the largeｒsｉzｅbｕt the thｉｃknessｍuｓt ｂｅsmaller gｅoｍetric featｕrｅｓshoｕlｄｂe ｐｒeｓented ｔo the pｌatｅ,ｔｈe forｃe is close to cylｉndrｉcal.Ｔhe waｌl sｈｅar wa ｌl strｕｃｔure ｉs a flaｔcomｐonent. Itｓeｘposure to tｈe force aｌoｎg ｔhe ｐlane leｖｅl of theｒole ofｓｈear and momｅｎt, must also take ｉｎtｏａccounｔthe veｒｔical preｓsure.Opeｒate unｄer thｅcomｂiｎed actｉｏn oｆbenｄing momeｎts and axial force aｎｄsheａr forcｅbｙthe caｎtilｅｖｅr deep beａm uｎder ｔｈe acｔion of the force leveｌｔo lｏo ｋinto ｔｈe bottom mouｎted on ｔhe basｉs of. Sheaｒｗaｌl ｉｓdiｖidｅｄinｔo a whole walｌand ｔheａssoｃiated ｓｈeａr wall in thｅactual project,a wholｅwａlｌfor ｅxａmpl ｅ, suｃh as ｇenｅraｌhｏusiｎｇｃonstｒuction in tｈe gablｅｏr fish bｏne strｕcture ｆｉlｍwａｌls ａnd small opｅningｓwall.Cｏupled Sｈeａr ｗalls are ｃonnｅcted bｙｔhｅcｏupｌing ｂeam shｅａr wall.Buｔｂecause tｈeｇｅnerａlｃｏupling beaｍstｉｆfness is less thaｎｔhe wall stiｆfnｅsｓof the lｉmbs，ｓｏ. Wａlｌliｍb aｌonｅis obviｏus.The ｃｅntral beam of tｈeｉnflｅｃtion pｏｉnｔtｏpay aｔtenｔiｏｎto tｈeｗaｌl pressｕre thａn the limiｔs of the lｉmb axis. Will forｍa shortｗiｄe beａms，widｅcolｕmn wａll liｍｂｓhear wａll ｏpｅnings toｏlarge ｃomｐonｅnt aｔbothｅn ｄs ｗith jｕst the domain of vａｒiabｌe crosｓ－ｓecｔｉon ro ｄin ｔhe intｅrｎａｌforcｅｓｕnder tｈｅaｃtioｎof maｎy Ｗalｌlｉmb iｎflｅcｔion point Ｔhｅｒeｆoｒe, ｔhe cａｌcula ｔions ａｎd consｔruction sｈouldAccordinｇtｏappｒoxiｍａｔe tｈe framｅstｒucｔure to ｃonsideｒ.Tｈe desｉｇｎof ｓhｅａr walls ｓhoulｄbe based on the cｈａractｅrisｔics ｏf ａvａｒｉｅty oｆwall itseｌｆ,ａnd dｉfferｅnｔmeｃhanical ch ａrａcteｒisｔｉcｓand requireｍents,wall oｆthｅinternａｌforceｄistrｉbutｉon and failurｅmoｄｅs ｏf sｐecific and cｏmprehensive ｃonｓideration of the design rｅinｆorcemｅnt aｎd stｒuctural measｕres. Ｆrame sｈear wall ｓｔrｕctuｒe deｓiｇn is to cｏｎsider the ｓtructｕre of the oｖerall ａnａｌysis for ｂoｔh dｉrecｔｉｏｎsｏｆthｅhｏrｉzontal and vｅrtiｃalｅfｆects. Oｂtain thｅinternal force ｉs reｑuirｅd in ａccｏrdancｅｗｉｔｈtｈe bias or paｒtｉal ｐull normal sｅcｔｉon forｃｅｃaｌculatiｏn.The waｌl strｕcture oｆtheｆｒame sｈear ｗall ｓｔructural dｅsign of ｔhe coｎtent frame hｉgh-rise buildings, in ｔhe actual ｐrｏjeｃｔiｎｔhｅuse of thｅｍoｓt seisｍic ｗａlls have suffiｃient quantitｉeｓto meｅt ｔheｌｉmitsｏf the lａyer displacement, the loｃation iｓｒelａtiｖely flexiblｅ. Seiｓmic wａll for cｏntinuous layout，ｆulｌ-length ｔhroｕgh．Should bｅdesigned to avoid the waｌl mutaｔioｎs ｉn limb ｌｅｎgth and alignment is noｔuｐａnd down the ｈolｅ. The samｅtｉme．Tｈe inｓide of ｔhe hole marginｓcｏlｕｍｎshｏｕld not ｂｅｌｅssｔhan３00mm ｉｎordｅｒtｏguaraｎteｅtheｌengtｈof the colｕｍn ａs the edgｅof tｈe coｍponent and constｒａiｎt eｄgｅcｏｍponeｎts．Thｅbi-direc ｔiｏnal laｔerａl forｃe ｒesiｓting strucｔurａl fｏrm of verticａl aｎｄhorｉzontaｌwalｌcoｎnected.Eａｃh ｏｔhｅr as ｔhe ａffiｎiｔｙof the shｅar wall. Ｆor ｏnｅ, two seismic frａme sｈe ａr ｗalｌｓ,ｅｖen beam highｒatio ｓhould noｔgreateｒthan 5 aｎd a height of nｏt less thaｎ400mm.Midline colｕmnａnd beａmｓ,wall ｍｉdline shouｌdｎoｔbe greaｔer tha ｎthe ｃoｌｕmｎwidｔｈof1/4，ｉn ordｅr ｔｏreｄuce thｅtoｒsional eｆfect of the sｅiｓmｉｃacｔion ｏnｔｈｅｃolｕmn．Oｔhｅrwｉsｅcan be taken tｏstrengthｅn theｓtirruprａｔｉo iｎｔhe cｏlｕmn tｏmake ｕp.If thｅshear wａｌl sheａｒsｐａn ｔhａnｔhe ｂig twｏ. Ｅveｎthe beａｍcro ｓs-heｉｇht ratiｏgreateｒthan 2.5, ｔhen tｈe design presｓｕｒe ｏf thｅｃｕt shoulｄnoｔmａkｅａｂig 0.2. Howevｅｒ, ｉf the sheａｒwallｓheａr sｐａｎｒatiｏof ｌess than two couｐlinｇｂeａms sｐan of ｌeｓs than ２．5, then the shear coｍｐres ｓiｏn rａｔiｏis noｔgreaｔer thａn 0.15. Thｅｏther haｎｄ，ｔhe bｏttom oｆthe fraｍe ｓhｅar walｌstructure ｔo enhａnce tｈｅdｅsign sｈould ｎoｔbe leｓs thaｎ２０0mmａnd noｔlesｓthaｎstorey 1/１6，othｅｒｐaｒtｓｓhｏulｄnot be lｅss than 160mm ａnd ｎｏt ｌｅss thaｎｓtoｒey １/20. Arounｄthe wall of the frame ｓhｅar ｗall strucｔure sｈｏulｄbe set ｔo the beａm or dark bｅamａnd the sｉｄe columｎｔｏform a borｄｅr. Ｈoｒizｏntａl ｄｉｓtrｉbuｔioｎoｆsｈear waｌls cａn from the sheａr effect，tｈｉs design wｈen ｂuilｄｉng higｈｅr longeｒor fｒaｍｅｓtructｕre reinfoｒcｅment shｏuld be aｐprｏpｒiatelｙincｒeａｓed, ｅspｅcｉａlｌy in the sｅnｓitivｅｐarts of the beam pｏsition ｏr teｍperaｔuｒe, stiffnｅsｓchａnge is besｔappｒopriatｅly increased, ｔｈeｎcｏnsidｅration sｈoulｄbe ｇｉveｎｔo the wａlｌvertｉcaｌreiｎforｃemeｎt,becaｕse ｉt is mａinly fｒom the bｅnding efｆecｔ, aｎｄtake in ｓome ｍｕlti-ｓtorｅｙshｅａｒｗａll structuｒereinforcｅｄreｉnｆorceｍent rate -likｅlｅsｓconｓtｒained edgｅｏｆｔhｅcomｐonent or components reinforｃemeｎt of thｅedge ｃomｐｏnent.Referｅnces: [1 sad Hａyaｓhi,He Yaming. Ｏn the shorｔshｅar ｗall ｈigh-riｓe bｕilｄinｇｄesign ［J]．Kｅｙｕaｎ, 2008, (O2).高层框架剪力墙结构设计吴继成摘要: 本文从框架剪力墙结构设计的基本概念人手, 分析了框架剪力墙的构造设计内容, 包括抗震墙、剪跨比等的设计, 并出混凝土结构中最常用的框架剪力墙结构设计的注意要点。
外文参考文献(带中文翻译)
外文资料原文涂敏之会计学 8051208076Title:Future of SME finance（c）Background – the environment for SME finance has changedFuture economic recovery will depend on the possibility of Crafts, Trades and SMEs to exploit their potential for growth and employment creation.SMEs make a major contribution to growth and employment in the EU and are at the heart of the Lisbon Strategy, whose main objective is to turn Europe into the most competitive and dynamic knowledge-based economy in the world. However, the ability of SMEs to grow depends highly on their potential to invest in restructuring, innovation and qualification. All of these investments need capital and therefore access to finance.Against this background the consistently repeated complaint of SMEs about their problems regarding access to finance is a highly relevant constraint that endangers the economic recovery of Europe.Changes in the finance sector influence the behavior of credit institutes towards Crafts, Trades and SMEs. Recent and ongoing developments in the banking sector add to the concerns of SMEs and will further endanger their access to finance. The main changes in the banking sector which influence SME finance are:•Globalization and internationalization have increased the competition and the profit orientation in the sector;•worsening of the economic situations in some institutes (burst of the ITC bubble, insolvencies) strengthen the focus on profitability further;•Mergers and restructuring created larger structures and many local branches, which had direct and personalized contacts with small enterprises, were closed;•up-coming implementation of new capital adequacy rules (Basel II) will also change SME business of the credit sector and will increase its administrative costs;•Stricter interpretation of State-Aide Rules by the European Commission eliminates the support of banks by public guarantees; many of the effected banks are very active in SME finance.All these changes result in a higher sensitivity for risks and profits in the financesector.The changes in the finance sector affect the accessibility of SMEs to finance.Higher risk awareness in the credit sector, a stronger focus on profitability and the ongoing restructuring in the finance sector change the framework for SME finance and influence the accessibility of SMEs to finance. The most important changes are: •In order to make the higher risk awareness operational, the credit sector introduces new rating systems and instruments for credit scoring;•Risk assessment of SMEs by banks will force the enterprises to present more and better quality information on their businesses;•Banks will try to pass through their additional costs for implementing and running the new capital regulations (Basel II) to their business clients;•due to the increase of competition on interest rates, the bank sector demands more and higher fees for its services (administration of accounts, payments systems, etc.), which are not only additional costs for SMEs but also limit their liquidity;•Small enterprises will lose their personal relationship with decision-makers in local branches –the credit application process will become more formal and anonymous and will probably lose longer;•the credit sector will lose more and more i ts “public function” to provide access to finance for a wide range of economic actors, which it has in a number of countries, in order to support and facilitate economic growth; the profitability of lending becomes the main focus of private credit institutions.All of these developments will make access to finance for SMEs even more difficult and / or will increase the cost of external finance. Business start-ups and SMEs, which want to enter new markets, may especially suffer from shortages regarding finance. A European Code of Conduct between Banks and SMEs would have allowed at least more transparency in the relations between Banks and SMEs and UEAPME regrets that the bank sector was not able to agree on such a commitment.Towards an encompassing policy approach to improve the access of Crafts, Trades and SMEs to financeAll analyses show that credits and loans will stay the main source of finance for the SME sector in Europe. Access to finance was always a main concern for SMEs, but the recent developments in the finance sector worsen the situation even more.Shortage of finance is already a relevant factor, which hinders economic recovery in Europe. Many SMEs are not able to finance their needs for investment.Therefore, UEAPME expects the new European Commission and the new European Parliament to strengthen their efforts to improve the framework conditions for SME finance. Europe’s Crafts, Trades and SMEs ask for an encompassing policy approach, which includes not only the conditions for SMEs’ access to l ending, but will also strengthen their capacity for internal finance and their access to external risk capital.From UEAPME’s point of view such an encompassing approach should be based on three guiding principles:•Risk-sharing between private investors, financial institutes, SMEs and public sector;•Increase of transparency of SMEs towards their external investors and lenders;•improving the regulatory environment for SME finance.Based on these principles and against the background of the changing environment for SME finance, UEAPME proposes policy measures in the following areas:1. New Capital Requirement Directive: SME friendly implementation of Basel IIDue to intensive lobbying activities, UEAPME, together with other Business Associations in Europe, has achieved some improvements in favour of SMEs regarding the new Basel Agreement on regulatory capital (Basel II). The final agreement from the Basel Committee contains a much more realistic approach toward the real risk situation of SME lending for the finance market and will allow the necessary room for adaptations, which respect the different regional traditions and institutional structures.However, the new regulatory system will influence the relations between Banks and SMEs and it will depend very much on the way it will be implemented into European law, whether Basel II becomes burdensome for SMEs and if it will reduce access to finance for them.The new Capital Accord form the Basel Committee gives the financial market authorities and herewith the European Institutions, a lot of flexibility. In about 70 areas they have room to adapt the Accord to their specific needs when implementing itinto EU law. Some of them will have important effects on the costs and the accessibility of finance for SMEs.UEAPME expects therefore from the new European Commission and the new European Parliament:•The implementation of the new Capital Requirement Directive will be costly for the Finance Sector (up to 30 Billion Euro till 2006) and its clients will have to pay for it. Therefore, the implementation – especially for smaller banks, which are often very active in SME finance –has to be carried out with as little administrative burdensome as possible (reporting obligations, statistics, etc.).•The European Regulators must recognize traditional instruments for collaterals (guarantees, etc.) as far as possible.•The European Commission and later the Member States should take over the recommendations from the European Parliament with regard to granularity, access to retail portfolio, maturity, partial use, adaptation of thresholds, etc., which will ease the burden on SME finance.2. SMEs need transparent rating proceduresDue to higher risk awareness of the finance sector and the needs of Basel II, many SMEs will be confronted for the first time with internal rating procedures or credit scoring systems by their banks. The bank will require more and better quality information from their clients and will assess them in a new way. Both up-coming developments are already causing increasing uncertainty amongst SMEs.In order to reduce this uncertainty and to allow SMEs to understand the principles of the new risk assessment, UEAPME demands transparent rating procedures –rating procedures may not become a “Black Box” for SMEs: •The bank should communicate the relevant criteria affecting the rating of SMEs.•The bank should inform SMEs about its assessment in order to allow SMEs to improve.The negotiations on a European Code of Conduct between Banks and SMEs , which would have included a self-commitment for transparent rating procedures by Banks, failed. Therefore, UEAPME expects from the new European Commission and the new European Parliament support for:•binding rules in the framework of the new Capital Adequacy Directive,which ensure the transparency of rating procedures and credit scoring systems for SMEs;•Elaboration of national Codes of Conduct in order to improve the relations between Banks and SMEs and to support the adaptation of SMEs to the new financial environment.3. SMEs need an extension of credit guarantee systems with a special focus on Micro-LendingBusiness start-ups, the transfer of businesses and innovative fast growth SMEs also depended in the past very often on public support to get access to finance. Increasing risk awareness by banks and the stricter interpretation of State Aid Rules will further increase the need for public support.Already now, there are credit guarantee schemes in many countries on the limit of their capacity and too many investment projects cannot be realized by SMEs.Experiences show that Public money, spent for supporting credit guarantees systems, is a very efficient instrument and has a much higher multiplying effect than other instruments. One Euro form the European Investment Funds can stimulate 30 Euro investments in SMEs (for venture capital funds the relation is only 1:2).Therefore, UEAPME expects the new European Commission and the new European Parliament to support:•The extension of funds for national credit guarantees schemes in the framework of the new Multi-Annual Programmed for Enterprises;•The development of new instruments for securitizations of SME portfolios;•The recognition of existing and well functioning credit guarantees schemes as collateral;•More flexibility within the European Instruments, because of national differences in the situation of SME finance;•The development of credit guarantees schemes in the new Member States;•The development of an SBIC-like scheme in the Member States to close the equity gap (0.2 – 2.5 Mio Euro, according to the expert meeting on PACE on April 27 in Luxemburg).•the development of a financial support scheme to encourage the internalizations of SMEs (currently there is no scheme available at EU level: termination of JOP, fading out of JEV).4. SMEs need company and income taxation systems, whichstrengthen their capacity for self-financingMany EU Member States have company and income taxation systems with negative incentives to build-up capital within the company by re-investing their profits. This is especially true for companies, which have to pay income taxes. Already in the past tax-regimes was one of the reasons for the higher dependence of Europe’s SMEs on bank lending. In future, the result of rating w ill also depend on the amount of capital in the company; the high dependence on lending will influence the access to lending. This is a vicious cycle, which has to be broken.Even though company and income taxation falls under the competence of Member States, UEAPME asks the new European Commission and the new European Parliament to publicly support tax-reforms, which will strengthen the capacity of Crafts, Trades and SME for self-financing. Thereby, a special focus on non-corporate companies is needed.5. Risk Capital – equity financingExternal equity financing does not have a real tradition in the SME sector. On the one hand, small enterprises and family business in general have traditionally not been very open towards external equity financing and are not used to informing transparently about their business.On the other hand, many investors of venture capital and similar forms of equity finance are very reluctant regarding investing their funds in smaller companies, which is more costly than investing bigger amounts in larger companies. Furthermore it is much more difficult to set out of such investments in smaller companies.Even though equity financing will never become the main source of financing for SMEs, it is an important instrument for highly innovative start-ups and fast growing companies and it has therefore to be further developed. UEAPME sees three pillars for such an approach where policy support is needed:Availability of venture capital•The Member States should review their taxation systems in order to create incentives to invest private money in all forms of venture capital.•Guarantee instruments for equity financing should be further developed.Improve the conditions for investing venture capital into SMEs•The development of secondary markets for venture capital investments in SMEs should be supported.•Accounting Standards for SMEs should be revised in order to easetransparent exchange of information between investor and owner-manager.Owner-managers must become more aware about the need for transparency towards investors•SME owners will have to realise that in future access to external finance (venture capital or lending) will depend much more on a transparent and open exchange of information about the situation and the perspectives of their companies.•In order to fulfil the new needs for transparency, SMEs will have to use new information instruments (business plans, financial reporting, etc.) and new management instruments (risk-management, financial management, etc.).外文资料翻译涂敏之会计学 8051208076题目：未来的中小企业融资背景：中小企业融资已经改变未来的经济复苏将取决于能否工艺品，贸易和中小企业利用其潜在的增长和创造就业。
道路与桥梁工程中英文对照外文翻译文献
中英文对照外文翻译(文档含英文原文和中文翻译)Bridge research in EuropeA brief outline is given of the development of the European Union, together with the research platform in Europe. The special case of post-tensioned bridges in the UK is discussed. In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio: relating to the identification of voids in post-tensioned concrete bridges using digital impulse radar.IntroductionThe challenge in any research arena is to harness the findings of different research groups to identify a coherent mass of data, which enables research and practice to be better focused. A particular challenge exists with respect to Europe where language barriers are inevitably very significant. The European Community was formed in the 1960s based upon a political will within continental Europe to avoid the European civil wars, which developed into World War 2 from 1939 to 1945. The strong political motivation formed the original community of which Britain was not a member. Many of the continental countries saw Britain’s interest as being purelyeconomic. The 1970s saw Britain joining what was then the European Economic Community (EEC) and the 1990s has seen the widening of the community to a European Union, EU, with certain political goals together with the objective of a common European currency.Notwithstanding these financial and political developments, civil engineering and bridge engineering in particular have found great difficulty in forming any kind of common thread. Indeed the educational systems for University training are quite different between Britain and the European continental countries. The formation of the EU funding schemes —e.g. Socrates, Brite Euram and other programs have helped significantly. The Socrates scheme is based upon the exchange of students between Universities in different member states. The Brite Euram scheme has involved technical research grants given to consortia of academics and industrial partners within a number of the states— a Brite Euram bid would normally be led by an industrialist.In terms of dissemination of knowledge, two quite different strands appear to have emerged. The UK and the USA have concentrated primarily upon disseminating basic research in refereed journal publications: ASCE, ICE and other journals. Whereas the continental Europeans have frequently disseminated basic research at conferences where the circulation of the proceedings is restricted.Additionally, language barriers have proved to be very difficult to break down. In countries where English is a strong second language there has been enthusiastic participation in international conferences based within continental Europe —e.g. Germany, Italy, Belgium, The Netherlands and Switzerland. However, countries where English is not a strong second language have been hesitant participants }—e.g. France.European researchExamples of research relating to bridges in Europe can be divided into three types of structure:Masonry arch bridgesBritain has the largest stock of masonry arch bridges. In certain regions of the UK up to 60% of the road bridges are historic stone masonry arch bridges originally constructed for horse drawn traffic. This is less common in other parts of Europe as many of these bridges were destroyed during World War 2.Concrete bridgesA large stock of concrete bridges was constructed during the 1950s, 1960s and 1970s. At the time, these structures were seen as maintenance free. Europe also has a large number of post-tensioned concrete bridges with steel tendon ducts preventing radar inspection. This is a particular problem in France and the UK.Steel bridgesSteel bridges went out of fashion in the UK due to their need for maintenance as perceived in the 1960s and 1970s. However, they have been used for long span and rail bridges, and they are now returning to fashion for motorway widening schemes in the UK.Research activity in EuropeIt gives an indication certain areas of expertise and work being undertaken in Europe, but is by no means exhaustive.In order to illustrate the type of European research being undertaken, an example is given from the University of Edinburgh portfolio. The example relates to the identification of voids in post-tensioned concrete bridges, using digital impulse radar.Post-tensioned concrete rail bridge analysisOve Arup and Partners carried out an inspection and assessment of the superstructure of a 160 m long post-tensioned, segmental railway bridge in Manchester to determine its load-carrying capacity prior to a transfer of ownership, for use in the Metrolink light rail system..Particular attention was paid to the integrity of its post-tensioned steel elements. Physical inspection, non-destructive radar testing and other exploratory methods were used to investigate for possible weaknesses in the bridge.Since the sudden collapse of Ynys-y-Gwas Bridge in Wales, UK in 1985, there has been concern about the long-term integrity of segmental, post-tensioned concrete bridges which may b e prone to ‘brittle’ failure without warning. The corrosion protection of the post-tensioned steel cables, where they pass through joints between the segments, has been identified as a major factor affecting the long-term durability and consequent strength of this type of bridge. The identification of voids in grouted tendon ducts at vulnerable positions is recognized as an important step in the detection of such corrosion.Description of bridgeGeneral arrangementBesses o’ th’ Barn Bridge is a 160 m long, three span, segmental, post-tensionedconcrete railway bridge built in 1969. The main span of 90 m crosses over both the M62 motorway and A665 Bury to Prestwick Road. Minimum headroom is 5.18 m from the A665 and the M62 is cleared by approx 12.5 m.The superstructure consists of a central hollow trapezoidal concrete box section 6.7 m high and 4 m wide. The majority of the south and central spans are constructed using 1.27 m long pre-cast concrete trapezoidal box units, post-tensioned together. This box section supports the in site concrete transverse cantilever slabs at bottom flange level, which carry the rail tracks and ballast.The center and south span sections are of post-tensioned construction. These post-tensioned sections have five types of pre-stressing:1. Longitudinal tendons in grouted ducts within the top and bottom flanges.2. Longitudinal internal draped tendons located alongside the webs. These are deflected at internal diaphragm positions and are encased in in site concrete.3. Longitudinal macalloy bars in the transverse cantilever slabs in the central span .4. Vertical macalloy bars in the 229 mm wide webs to enhance shear capacity.5. Transverse macalloy bars through the bottom flange to support the transverse cantilever slabs.Segmental constructionThe pre-cast segmental system of construction used for the south and center span sections was an alternative method proposed by the contractor. Current thinking suggests that such a form of construction can lead to ‘brittle’ failure of the ent ire structure without warning due to corrosion of tendons across a construction joint，The original design concept had been for in site concrete construction.Inspection and assessmentInspectionInspection work was undertaken in a number of phases and was linked with the testing required for the structure. The initial inspections recorded a number of visible problems including:Defective waterproofing on the exposed surface of the top flange.Water trapped in the internal space of the hollow box with depths up to 300 mm.Various drainage problems at joints and abutments.Longitudinal cracking of the exposed soffit of the central span.Longitudinal cracking on sides of the top flange of the pre-stressed sections.Widespread sapling on some in site concrete surfaces with exposed rusting reinforcement.AssessmentThe subject of an earlier paper, the objectives of the assessment were:Estimate the present load-carrying capacity.Identify any structural deficiencies in the original design.Determine reasons for existing problems identified by the inspection.Conclusion to the inspection and assessmentFollowing the inspection and the analytical assessment one major element of doubt still existed. This concerned the condition of the embedded pre-stressing wires, strands, cables or bars. For the purpose of structural analysis these elements、had been assumed to be sound. However, due to the very high forces involved,、a risk to the structure, caused by corrosion to these primary elements, was identified.The initial recommendations which completed the first phase of the assessment were:1. Carry out detailed material testing to determine the condition of hidden structural elements, in particularthe grouted post-tensioned steel cables.2. Conduct concrete durability tests.3. Undertake repairs to defective waterproofing and surface defects in concrete.Testing proceduresNon-destructi v e radar testingDuring the first phase investigation at a joint between pre-cast deck segments the observation of a void in a post-tensioned cable duct gave rise to serious concern about corrosion and the integrity of the pre-stress. However, the extent of this problem was extremely difficult to determine. The bridge contains 93 joints with an average of 24 cables passing through each joint, i.e. there were approx. 2200 positions where investigations could be carried out. A typical section through such a joint is that the 24 draped tendons within the spine did not give rise to concern because these were protected by in site concrete poured without joints after the cables had been stressed.As it was clearly impractical to consider physically exposing all tendon/joint intersections, radar was used to investigate a large numbers of tendons and hence locate duct voids within a modest timescale. It was fortunate that the corrugated steel ducts around the tendons were discontinuous through the joints which allowed theradar to detect the tendons and voids. The problem, however, was still highly complex due to the high density of other steel elements which could interfere with the radar signals and the fact that the area of interest was at most 102 mm wide and embedded between 150 mm and 800 mm deep in thick concrete slabs.Trial radar investigations.Three companies were invited to visit the bridge and conduct a trial investigation. One company decided not to proceed. The remaining two were given 2 weeks to mobilize, test and report. Their results were then compared with physical explorations.To make the comparisons, observation holes were drilled vertically downwards into the ducts at a selection of 10 locations which included several where voids were predicted and several where the ducts were predicted to be fully grouted. A 25-mm diameter hole was required in order to facilitate use of the chosen horoscope. The results from the University of Edinburgh yielded an accuracy of around 60%.Main radar sur v ey, horoscope verification of v oids.Having completed a radar survey of the total structure, a baroscopic was then used to investigate all predicted voids and in more than 60% of cases this gave a clear confirmation of the radar findings. In several other cases some evidence of honeycombing in the in site stitch concrete above the duct was found.When viewing voids through the baroscopic, however, it proved impossible to determine their actual size or how far they extended along the tendon ducts although they only appeared to occupy less than the top 25% of the duct diameter. Most of these voids, in fact, were smaller than the diameter of the flexible baroscopic being used (approximately 9 mm) and were seen between the horizontal top surface of the grout and the curved upper limit of the duct. In a very few cases the tops of the pre-stressing strands were visible above the grout but no sign of any trapped water was seen. It was not possible, using the baroscopic, to see whether those cables were corroded.Digital radar testingThe test method involved exciting the joints using radio frequency radar antenna: 1 GHz, 900 MHz and 500 MHz. The highest frequency gives the highest resolution but has shallow depth penetration in the concrete. The lowest frequency gives the greatest depth penetration but yields lower resolution.The data collected on the radar sweeps were recorded on a GSSI SIR System 10.This system involves radar pulsing and recording. The data from the antenna is transformed from an analogue signal to a digital signal using a 16-bit analogue digital converter giving a very high resolution for subsequent data processing. The data is displayed on site on a high-resolution color monitor. Following visual inspection it is then stored digitally on a 2.3-gigabyte tape for subsequent analysis and signal processing. The tape first of all records a ‘header’ noting the digital radar settings together with the trace number prior to recording the actual data. When the data is played back, one is able to clearly identify all the relevant settings —making for accurate and reliable data reproduction.At particular locations along the traces, the trace was marked using a marker switch on the recording unit or the antenna.All the digital records were subsequently downloaded at the University’s NDT laboratory on to a micro-computer.（The raw data prior to processing consumed 35 megabytes of digital data.）Post-processing was undertaken using sophisticated signal processing software. Techniques available for the analysis include changing the color transform and changing the scales from linear to a skewed distribution in order to highlight、突出certain features. Also, the color transforms could be changed to highlight phase changes. In addition to these color transform facilities, sophisticated horizontal and vertical filtering procedures are available. Using a large screen monitor it is possible to display in split screens the raw data and the transformed processed data. Thus one is able to get an accurate indication of the processing which has taken place. The computer screen displays the time domain calibrations of the reflected signals on the vertical axis.A further facility of the software was the ability to display the individual radar pulses as time domain wiggle plots. This was a particularly valuable feature when looking at individual records in the vicinity of the tendons.Interpretation of findingsA full analysis of findings is given elsewhere, Essentially the digitized radar plots were transformed to color line scans and where double phase shifts were identified in the joints, then voiding was diagnosed.Conclusions1. An outline of the bridge research platform in Europe is given.2. The use of impulse radar has contributed considerably to the level of confidence in the assessment of the Besses o’ th’ Barn Rail Bridge.3. The radar investigations revealed extensive voiding within the post-tensioned cable ducts. However, no sign of corrosion on the stressing wires had been found except for the very first investigation.欧洲桥梁研究欧洲联盟共同的研究平台诞生于欧洲联盟。
文献翻译模板
2016届本科毕业设计（论文）文献翻译题目宋体三号字，加粗学院宋体四号字专业宋体四号字班级宋体四号字学号宋体四号字姓名宋体四号字指导教师宋体四号字开题日期宋体四号字文献一：（宋体五号）英文题目(居中，Times New Roman字体，三号加粗)正文（英文不少于10000印刷符号，Times New Roman字体，五号，首行缩进2.5字符，单倍行距，两边对齐）翻译一：（宋体五号，另起一页）中文题目(居中，黑体，三号加粗)正文（中文不少于2000字，宋体，五号，单倍行距，首行缩进2字符）文献二：（宋体五号，另起一页）英文题目(居中，Times New Roman字体，三号加粗)正文（英文不少于10000印刷符号，Times New Roman字体，五号，首行缩进2.5字符，单倍行距，两边对齐）翻译二：（宋体五号，另起一页）中文题目(居中，黑体，三号加粗)正文（中文不少于2000字，宋体，五号，单倍行距，首行缩进2字符）（请参照下面模板）文献一：Research on Spillover Effect of Foreign Direct Investment1. IntroductionIn recent decades, economists have begun to identify technical progress, or more generally, knowledge creation, as the major determinant of economic growth. Until the 1970s, the analysis of economic growth was typically based on neoclassical models that explain growth with the accumulation of labor, capital, and other production factors with diminishing returns to scale. In these models, the economy converges to steady state equilibrium where the level of per capita income is determined by savings and investment, depreciation, and population growth, but where there is no permanent income growth. Any observed income growth per capita occurs because the economy is still converging towards its steady state, or because it is in transition from one steady state to another.The policies needed to achieve growth and development in the framework of these models is therefore straightforward: increases in savings and investments and reductions in the population growth rate, shift the economy to a higher steady state income level. From the view of developing countries, however, these policies are difficult to implement. Low income and development levels are not only consequences, but also causes of low savings and high population growth rates. The importance of technical progress was also recognized in the neoclassical growth models, but the determinants of the level of technology were not discussed in detail; instead, technology was seen as an exogenous factor. Yet, it was clear that convergence in income percapita levels could not occur unless technologies converged as well.From the 1980s and onwards, growth research has therefore increasingly focused on understanding and ontogenetic technical progress. Modern growth theory is largely built on models with constant or increasing returns to reproducible factors as a result of the accumulation of knowledge. Knowledge is, to some extent, a public good, and R&D, education, training, and other investments in knowledge creation may generate externalities that prevent diminishing returns to scale for labor and physical capital. Taking this into account, the economy may experience positive long-run growth instead of the neoclassical steady state where per capita incomes remain unchanged. Depending on the economic starting point, technical progress and growth can be based on creation of entirely new knowledge, or adaptation and transfer of existing foreign technology.Along with international trade, the most important vehicle for international technology transfer is foreign direct investment (FDI). It is well known that multinational corporations (MNCs) undertake a major part of the world’s private R&D efforts and production, own and control most of the world’s advanced technology. When a MNC sets up a forei gn affiliate, the affiliate receives some amount of the proprietary technology that constitutes the parent’s firm specific advantage and allows it to compete successfully with local firms that have superior knowledge of local markets, consumer preferences, and business practices. This leads to a geographical diffusion of technology, but not necessarily to any formal transfer of technology beyond the boundaries of the MNCs; the establishment of a foreign affiliate is, almost per definition, a decision to internalize the use of core technology.However, MNC technology may still leak to the surrounding economy through external effects or spillovers that raise the level of human capital in the host country and createproductivity increases in local firms. In many cases, the effects operate through forward and backward linkages, as MNCs provide training and technical assistance to their local suppliers, subcontractors, and customers. The labor market is another important channel for spillovers, as almost all MNCs train operatives and managers who may subsequently take employment in local firms or establish entirely new companies.It is therefore not surprising that attitudes towards inward FDI have changed considerably over the last couple of decades, as most countries have liberalized their policies to attract all kinds of foreign investment. Numerous governments have even introduced various forms of investment incentives to encourage foreign MNCs to invest in their jurisdiction. However, productivity and technology spillovers are not automatic consequences of FDI. Instead, FDI and human capital interact in a complex manner, where FDI inflows create a potential for spillovers of knowledge to the local labor force, at the same time as the host country’s level of human capital determines how much FDI it can attract and whether local firms are able to absorb the potential spillover benefits.2. Foreign Direct Investment and SpilloversThe earliest discussions of spillovers in the literature on foreign direct investment date back to the 1960s. The first author who systematically introduced spillovers (or external effects) among the possible consequences of FDI was MacDougall (1960), who analyzed the general welfare effects of foreign investment. The common aim of the studies was to identify the various costs and benefits of FDI.Productivity externalities were discussed together with several other indirect effects that influence the welfare assessment, such as those arising from the impact of FDI on government revenue, tax policies, terms of trade, and the balance of payments. The fact that spillovers included in the discussion was generally motivated by empirical evidence from case studies rather than by comprehensive theoretical arguments.Yet, the early analyses made clear that multinationals may improve locatives efficiency by entering into industries with high entry barriers and reducing monopolistic distortions, and induce higher technical efficiency if the increased competitive pressure or some demonstration effect spurs local firms to more efficient use of existing resources. They also proposed that the presence may lead to increases in the rate of technology transfer and diffusion. More specifically, case studies showed that foreign MNCs may:(1) Contribute to efficiency by breaking supply bottlenecks (but that the effect may become less important as the technology of the host country advances);(2) Introduce new know-how by demonstrating new technologies and training workers who later take employment in local firms;(3) Either break down monopolies and stimulate competition and efficiency or create a more monopolistic industry structure, depending on the strength and responses of the local firms;(4) Transfer techniques for inventory and quality control and standardization to their local suppliers and distribution channels;Although this diverse list gives some clues about the broad range of various spillover effects, it says little about how common or how important they are in general. Similar complaints can be made about the evidence on spillovers gauged from the numerous case studies discussing various aspects of FDI in different countries and industries. These studies often contain valuable circumstantial evidence of spillovers, but often fail to show how significant the spillover effectsare and whether the results can be generalized.For instance, many analyses of the linkages between MNCs and their local suppliers and subcontractors have documented learning and technology transfers that may make up a basis for productivity spillovers or market access spillovers. However, these studies seldom reveal whether the MNCs are able to extract all the benefits that the new technologies or information generate among their supplier firms. Hence, there is no clear proof of spillovers, but it is reasonable to assume that spillovers are positively related to the extent of linkages.Similarly, there are many works on the relation between MNCs entry and presence and market structure in host countries, and this is closely related to the possible effects of FDI on competition in the local markets. There are also case studies of demonstration effects, technology diffusion, and labor training in foreign MNCs. However, although these studies provide much detailed information about the various channels for spillovers, they say little about the overall significance of such spillovers.The statistical studies of spillovers, by contrast, may reveal the overall impact of foreign presence on the productivity of local firms, but they are generally not able to say much about how the effects come about. These studies typically estimate production functions for locally owned firms, and include the foreign share of the industry as one of the explanatory variables. They then test whether foreign presence has a significant positive impact on local productivity once other firm and industry characteristics have been accounted.Research conclude that domestic firms exhibited higher productivity in sectors with a larger foreign share, but argue that it may be wrong to conclude that spillovers have taken place if MNC affiliates systematically locate in the more productive sectors. In addition, they are also able to perform some more detailed tests of regional differences in spillovers. Examining the geographical dispersion of foreign investment, they suggest that the positive impact of FDI accrue mainly to the domestic firms located close to the MNC affiliates. However, effects seem to vary between industries.The results on the presence of spillovers seem to be mixed; recent studies suggest that there should be a systematic pattern where various host industry and host country characteristics influence the incidence of spillovers. For instance, the foreign affiliate’s levels of tech nology or technology imports seem to influence the amount of spillovers to local firms. The technology imports of MNC affiliates, in turn, have been shown to vary systematically with host country characteristics. These imports seem larger in countries and industries where the educational level of the local labor force is higher, where local competition is tougher, and where the host country imposes fewer formal requirements on the affiliates’ operations.Some recent studies have also addressed the apparent contradictions between the earlier statistical spillover studies, with the hypothesis that the host country’s level of technical development or human capital may matter as a starting point.In fact, in some cases, large foreign presence may even be a sign of a weak local industry, where local firms have not been able to absorb any productivity spillovers at all and have therefore been forced to yield market shares to the foreign MNCs.3. FDI Spillover and Human Capital DevelopmentThe transfer of technology from MNC parents to its affiliates and other host country firms is not only mbodied in machinery, equipment, patent rights, and expatriate managers and technicians,but is also realized rough the training of local employees. This training affects most levels of employees, from simple manufacturing operatives through supervisors to technically advanced professionals and top-level managers. While most recipients of training are employed in the MNCs own affiliates, the beneficiaries also include employees among the MNCs suppliers, subcontractors, and customers.Types of training ranged from on-the-job training to seminars and more formal schooling to overseas education, perhaps at the parent company, depending on the skills needed. The various skills gained through the elation with the foreign MNCs may spill over directly when the MNCs do not charge the full value of the training provided to local firms or over time, as the employees move to other firms or set up their own businesses.While the role of MNCs in primary and secondary education is marginal, there is increasingly clear evidence hat FDI may have a noticeable impact on tertiary education in their host countries. The most important effect is perhaps on the demand side. MNCs provide attractive employment opportunities to highly skilled graduates in natural sciences, engineering, and business sciences, which may be an incentive for gifted students to complete tertiary training, and MNCs demand skilled labor, which may encourage governments to invest in higher education.Many studies undertaken in developing countries have emphasized the spillovers of management skills. There is evidence of training and capacity development in technical areas, although the number of detailed studies appears smaller.While training activities in manufacturing often aim to facilitate the introduction of new technologies that are embodied in machinery and equipments, the training in service sectors is more directly focused on strengthening skills and know-how embodied in employees. This means that training and human capital development are often more important in service industries. Furthermore, many services are not tradable across international borders, which mean that service MNCs to a great extent are forced to reproduce home country technologies in their foreign affiliates. As a consequence, service companies are often forced to invest more in training, and the gap between affiliate and parent company wages tends, therefore, to be smaller than that in manufacturing.4. ConclusionThis paper has noted that the interaction of FDI and spillovers is complex and highly non-linear, and that several different outcomes are possible. FDI inflows create a potential for spillovers of knowledge to the local labor force, at the same time as the host country’s level of human capital determines how much FDI it can attract and whether local firms are able to absorb the potential spillover benefits. Hence, it is possible that host economies with relatively high levels of human capital may be able to attract large amounts of technology intensive foreign MNCs that contribute significantly to the further development of labor skills. At the same time, economies with weaker initial conditions are likely to experience smaller inflows of FDI, and those foreign firms that enter are likely to use simpler technologies that contribute only marginally to local learning and skill development.翻译一：外商直接投资溢出效应研究1.引言在最近几十年中，经济学家们已开始确定技术进步，或更普遍认为知识创造，作为经济增长原动力的一个重要决定因素，直到20世纪70年代，分析经济增长运用典型的新古典主义模型来解释经济增长的积累，劳动力、资本等生产要素与收益递减的规模。
翻译论文英文参考文献
翻译论文英文参考文献1. 乔海清. 《翻译新论》. 北京：北京语言学院出版社. 1993.2. 邵志洪. 《翻译理论、实践与评析》. 上海：华东理工大学出版社, 2021.3. 邵志洪. 《英汉语研究与对比》. 上海：华东理工大学出版社, 1997.4. 申丹. 《文学文体学与小说翻译》. 北京：北京大学出版社. 1995.5. 申小龙. 《语言的文化阐释》. 上海：知识出版社, 1992.6. 申小龙. 《汉语句型研究》. 海口：海南人民出版社, 1989.7. 申小龙. 《汉语与中国文化》. 上海：复旦大学出版社, 2021.8. 申小龙. 《文化语言学》. 南昌：江西教育出版社, 1993.9. 申雨平编. 《西方翻译理论精选》. 北京：外语教学与研究出版社. 2002.10. 沈少华. 《英语趣味修辞格》. 北京：语文出版社, 1999.11. 思果. 《译道探微》. 北京：中国对外翻译出版公司. 2002.12. 孙全洲. 《现代汉语学习词典》. 上海：上海外语教育出版社, 1996.13. 孙晓丽. 《广告英语与实例》. 北京：中国广播电视出版社, 1995.14. 孙致礼. 《1949-1966：我国英美文学翻译概论》. 南京：译林出版社. 1996.15. 谭载喜. 《翻译学》. 武汉：湖北教育出版社. 2000.16. 谭载喜. 《新编奈达论翻译》. 北京：中国对外翻译出版公司. 1999.17. 倜西、董乐山等编. 《英汉翻译手册》. 北京：商务印书馆国际有限公司. 2002.1. 王德春. 《语言学通论》. 南京：江苏教育出版社, 1990.2. 王逢鑫. 《英汉比较语义学》. 北京：外文出版社, 2001.3. 王还主编. 《汉英对比论文集》. 北京：北京语言学院出版社. 1993.4. 王季思. 《中国十大古典喜剧集》. 上海：上海文艺出版社, 1982.5. 王克非. 《翻译文化史论》. 上海：上海外语教育出版社. 1997.6. 王令坤主编. 《英汉翻译技巧》. 上海：上海交通大学出版社. 1998.7. 王希杰. 《汉语修辞学》. 北京：北京出版社, 1983.8. 王希杰. 《修辞学导论》. 杭州：浙江教育出版社, 2000.9. 王佐良、丁往道. 《英语文体学引论》. 北京：外语教学与研究出版社, 1990.10. 王佐良. 《翻译：思考与试笔》. 北京：外语教学与研究出版社, 1989.11. 魏志成. 《英汉语比较导论》. 上海：上海外语教育出版社. 2021.12. 魏志成. 《英汉语比较导论》. 上海：上海外语教育出版社. 2021.13. 翁显良. 《意态由来画不成?》北京：中国对外翻译出版公司, 1983.1. 陈保亚 20 世纪中国语言学方法论济南：山东教育出版社，19992. 丁言仁英语语言学纲要上海：上海外语出版社，20013. 费尔迪南德索绪尔普通语言学教程长沙：湖南教育出版社，20014. 冯翠华英语修辞大全北京：商务印书馆，19965. 桂诗春，宁春言主编语言学方法论北京：外语教学与研究出版社，19986. 桂诗春应用语言学长沙：湖南教育出版社，19987. 何兆熊新编语用学概要上海：上海外语教育出版社，20008. 何自然语用学与英语学习上海：上海外语教育出版社，19979. 侯维瑞英语语体上海：上海外语教育出版社，198810. 胡壮麟语言学教程修订版北京：北京大学出版社，200111. 黄国文语篇与语言的功能北京：外语教学与研究出版社，200212. 黄国文语篇分析概要长沙：湖南教育出版社，1988感谢您的阅读，祝您生活愉快。
外文文献翻译封面格式及要求(模版)
毕业论文外文文献翻译院年级专业：2009级XXXXXXXXXXX 姓 名：学 号：附 件：备注：(注意：备注页这一整页的内容都不需要打印，看懂了即可）1.从所引用的与毕业设计（论文）内容相近的外文文献中选择一篇或一部分进行翻译(不少于3000实词)；2。
外文文献翻译的装订分两部分，第一部分为外文文献；第二部分为该外文文献的中文翻译，两部分之间用分页符隔开.也就是说，第一外文文献部分结束后，使用分页符，另起一页开始翻译。
3。
格式方面，外文文献的格式，除了字体统一使用Times new roman 之外，其他所有都跟中文论文的格式一样.中文翻译的格式,跟中文论文的格式一样。
(注意:备注页这一整页的内容都不需要打印，看懂了即可，定稿后,请删除本页.）范文如下:注意,下面内容每一部份均已用分页符分开了，如果用本模板,请将每一模块单独删除,直接套用到每一模板里面，不要将全部内容一次性删除。
【Abstract】This paper has a systematic analysis on outside Marco—environment of herbal tea beverage industry and major competitors of brands inside the herbal tea market。
Based onthe theoretic framework, this paper takes WONG LO KAT and JIA DUO BAO herbal tea as an example, and researches the strategy on brand positioning and relevant marketing mix of it. Through analysis on the prevention sense of WONG LO KAT herbal tea, it was positioned the beverage that can prevent excessive internal heat in body, a new category divided from the beverage market。
外文文献翻译
外文文献翻译Finance companies originate subprime automobile loans using a network of franchises and car dealers. They may fund this lending with traditional debt or equity, but in the 1990s many of these companies also began to issue asset-backed securities. In a typical automobile securitization, an originator pools several thousand automobile loans and sells these to a special-purpose entity such as a trust. The special-purpose entity, in turn, issues securities backed by a beneficial interest in the receivables from the loans in the pool. Typically, the originator continues to service the loans for a fee. Depending on credit enhancements, asset quality, servicer strength, and other variables, these securities are assigned a credit rating and can be traded in capital markets.It is possible that the automobile loans that underly asset-backed securities are not representative of all loans made by finance companies. For example, some lenders may choose to "cherry pick" by securitizing only their relatively less desirable loans. We believe this potential source of selection bias is of limited practical importance because several of the largest finance companies represented in our sample have adopted explicit policies of securitizing all or nearly all of the loans they originate. Unfortunately, data comparing the characteristics of on- and off- balance sheet automobile loan portfolios are not publicly available.Each issuer of publicly-traded automobile loan-backed securities submits periodic reports to the SEC documenting the performance of the underlying collateral pool. Using these data and other sources, Moody's publishes New Issue Reports describing each collateral pool and Pool Performance Reportsthat track the performance of pools over time. Among the variables included in a typical New Issue Report are the initial weighted average interest rate (termed weighted average coupon, or WAC), the weighted average maturity, and the age of loans in a pool, as well as the initial number of loans and asset balance for the pool. Variables available on a monthly frequency from Pool Performance Reports include the principal balance on loans outstanding, delinquency rates, dollars charged-off, and dollars prepaid for active pools.We have compiled sufficient data from Moody's New Issue and PoolPerformance reports to construct a sample of 3,595 pool-month observations on 124 loan pools from 13 different issuers.A total of 3.3 million automobile loans were held in these pools. Table 1 reports summary statistics for our sample of loan pools. Figure 1 provides information on pool issue dates, pool sizes, and WACs. Although some of the pools in our sample were issued during 1994, 1995, and 1996, performance data for most pools are only available after 1996.The fundamental unit of analysis for examining default and prepayment risk is the individual loan. The aggregate competing risks model described in Section 3 requires information on the number of loans that default and prepay in each month in the life of a pool. Because these data are not directly reported by Moody's, we must infer them from available accounting data. To accomplish this, we first calculate the average remaining balance for active loans in a pool by using information on the pool's average loan size, weighted average coupon, and maturity in a standard amortization formula. We then estimate the number of prepaid loans by dividing the reported dollars of principalprepaid in a month by the estimated average remaining loan principal balance for that month.Estimating the number of loans that default in a month requires that we make an assumption about the relationship between charge-offs and loan defaults. We assume that when a loan defaults, sixty percent of its remaining principal is charged off. The number of loans that default is estimated by dividing the reported dollars charged off in a month by the estimated principal balance scaled to reflect the charge-off assumption. The sixty percent charge-off rule represents what we take to be a reasonable approximation of standard practice based on discussions with industry participants. Unfortunately, the detailed accounting data needed to either validate or generalize this simple rule are not publicly available. To the extent that our sixty percent charge-off assumption is too high (respectively, too low) we will under (over) predict default probabilities. Nonetheless, our conclusions about the economic drivers of default and prepayment risk should be robust to reasonable departures from this assumption.财务公司发起的次级汽车贷款，使用网络的专营权和汽车经销商。
翻译的英文文献.pdf
Journal of Hazardous Materials 273 (2014) 136–145Contents lists available at ScienceDirectJournal of Hazardous Materialsj o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / j h a z m a tEnvironment-oriented low-cost porous mullite ceramic membrane supports fabricated from coal gangue and bauxiteQikai Lüa ,b ,c, Xinfa Dong c , Zhiwen Zhua ,b, Yingchao Donga ,b ,∗a Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, PR ChinabNingbo Urban Environment Observation and Research Station-NUEORS, Chinese Academy of Sciences, Ningbo, PRChina cSchool of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, PR Chinah i g h l i g h t s• Coal gangue was recycled to fabricate low-cost porous mullite membrane supports. • A unique volume-expansion occurred due to a mullitization-crystal-growth process. • A porous structure consists of glassy particles and embedded mullite crystals.a r t i c l e i n f oArticle history:Received 23 December 2013Received in revised form 20 February 2014 Accepted 19 March 2014Available online 27 March 2014Keywords:Coal gangueWaste recyclingCeramic membranePorous mulliteMechanical strengtha b s t r a c tPorous mullite ceramic supports for filtration membrane were successfully fabricated via recycling of coal gangueand bauxite at sintering temperatures from 1100 to 1500 ◦C with corn starch as pore-forming agent. The dynamic sintering behaviors, phase evolution, shrinkage, porosity and pore size, gas permeation flux, microstructure and mechanical property were systematically studied. A unique volume-expansion stage was observed at increasedtemperatures from 1276 to 1481 ◦C caused by a mullitization-crystal-growth process. During this stage, openporosity increases and pore size distribu-tions broaden, which result in a maximum of nitrogen gas flux at 1400 ◦C.The X-ray diffraction results reveal that secondary mullitization took place from 1100 ◦C and the major phase ismullite with a con-tent of ∼84.7 wt.% at 1400 ◦C. SEM images show that the as-fabricated mullite supports have a porous microstructure composed of sintered glassy particles embedded with inter-locked mullite crystals, which grew gradually with increasing temperature from rod-like into blocky-like morphologies. To obtain mul-lite membrane supports with sufficient porosity and acceptable mechanical strength, the relationship between porosity and mechanical strength was investigated, which was fitted using a parabolic equation.© 2014 Elsevier B.V. All rights reserved.1. IntroductionCoal gangue, an industrial solid waste, is one of the by-products during coal mining. The production ratio of coal gangue varies from ∼10% to 15% of raw coal, which mainly depends on mining and geo-logical conditions [1,2]. Currently most of waste coal gangue is piled on land, which can cause serious environmental impacts, especially the atmospheric pollution caused from spontaneous combustion and water pollution from leaching and release of heavy metal ions∗ Corresponding author at: Institute of Urban Environment (IUE) Chinese Academy of Sciences (CAS), Inorganic Membrane & Environmental Materials, 1799, Jimei Road, Xiamen, Fujian Province 361021, PR China. Tel.: +86 592 6190790; fax: +86 592 6190790.E-mail address: ycdong@ (Y. Dong)./10.1016/j.jhazmat.2014.03.026 0304-3894/© 2014 Elsevier B.V. All rights reserved.[3–5]. Therefore, the comprehensive utilization of coal gangue is quite necessary. Many approaches on reusing of coal gangue have been reported so far. Most of coal gangue after processing is used for traditional construction materials, such as cement [6] and brick [7]. The coal gangue with high content of carbon is mixed with other types of coal for mine-mouth power generation, which has indi-cated its techno-economic feasibility of mine-mouth power plants [8]. In general, the major mineralogical phase composition of coal gangue is quartz and feldspar [9,10], with main chemical compo-sition of SiO 2 , Al 2 O 3 , Fe 2 O 3 and some other minor oxide such as K 2 O and TiO 2 . Compared with other industrial wastes and minerals such as coal fly ash, kaolin, andalusite and sillimanite, particularly, the content of SiO 2 in coal gangue is generally as high as ∼70%, so it can be considered as a potential low-cost silicon source in industry. There are some studies on the fabrication of glasses and ceramics by reusing of coal gangue. Yang et al. prepared a CaO –Al 2 O 3 –SiO 2Q. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145 137glass ceramic from coal gangue [11], and -SiC/Al 2 O 3 ceramics have been fabricated from kaolinite gangue and anthracite by Han et al. [12].Porous ceramic separation membranes have been widely studied for energy and environmental applications due to its unique advantages especially such as high thermal, chemical and mechanical stability, environment friendliness and low energy-consumption [13]. However, because porous ceramic separation membranes require a much higher cost than polymeric counter-parts, their applications have been limited in some traditional industry such as food, beverage and pharmaceutical. Also, limited types of membrane materials (such as Al 2 O 3 , ZrO 2 , TiO 2 and their composite oxides) hinder their further applications [14–16]. With increased needs of some environmental separation applications such as strong acidic/alkaline media separation, massive waste liq-uid pre-treatment and low-cost catalysis-separation supports, it is of great importance to develop low-cost fabrication and application techniques for ceramic membranes.Among ceramic membrane materials, porous mullite (from 3Al 2 O 3 ·2SiO 2 to 2Al 2 O 3 ·SiO 2 ) has been attracting more and more attentions as membrane supports because of its unique advan-tages such as good chemical durability, low thermal expansion coefficient, good mechanical property and abundant Si- and Al-sources [17]. In order to further reduce cost, many researchers have been devoted to fabrication of porous mullite using various cheap raw materials such as fly ash [18,19], kaolin [20–23], andalusite [24] and sillimanite [25–27]. However, to the best of our knowl-edge, there are few reports on recycling of industrial solid waste coal gangue in fabrication of porous mullite ceramic membrane, which is an important route to decrease membrane processing cost. This method will be expected to be an effective way to reuse coal gangue not only to give a new and facile insight for solving its envi-ronment problems but also to endow a possibility of high-valued recycling.In this study, in order to recycle coal gangue, porous mullite ceramic membrane supports were fabricated using coal gangue and bauxite. The properties of porous mullite ceramic membrane supports were characterized and discussed, including dynamic sintering behaviors, phase evolution, shrinkage, porosity and pore size, gas permeation flux, microstructure and mechani-cal property. Corn starch powder was added as pore-forming agent to produce sufficient porosity with acceptable mechanical property.2. Experimental procedures2.1. Sample preparationIndustrial coal gangue (after 800 ◦C calcination, Xiamen, Fujian Province, China) and calcined bauxite (after 1200 ◦C calcination, Gongyi, Henan Province, China) powders were used as the mate-rials for the preparation of porous mullite membrane supports. Commercial corn starch ((C 6 H 10 O 5 )n , Beijing Gusong Economic and Trade Co., Ltd., China,D 50 = 16.84 m) was used as pore-forming agent.Based on the composition of 3:2 mullite (3Al 2 O 3 ·2SiO 2 ), a batch of coal gangue and bauxite powders was weighed and then wet-mixed using zirconia-ball-milling at a constant rotation speed of 500 rpm for10 h at room temperature, and subsequently dried at 90 ◦C for 1 day. On one hand, the powder mixture was mixed with organic binder PVA-1750 (5 wt.% solution) in an alumina mortar, and then uniaxially pressed into pellets (∼1.0 g each sample) with diameter of 20 mm at 190 MPa to obtain the green samples with-out pore-forming agent. On the other hand, the powder mixture was mixed with organic binder PVA-1750 (5 wt.% solution) andvarious contents of corn starch in an alumina mortar, and then uni-axially pressed into pellets (∼1.0 g each sample) with diameter of 20 mm at 190 MPa to obtain the green samples with pore-forming agent. Afterwards, the green pellets were placed in a muffle furnace (KSL-1700X, Hefei Kejing Materials Technology Co. Ltd., China) andsintered at temperatures from 1100 to 1500 ◦C for 2 h. The heatingrates were 1 ◦ C up to 450 ◦ C, 2 ◦ C up to 600 ◦ C, and 3 ◦C up to finaltemperature. A holding time of 0.5 h was carried out at 450 and 600 ◦C to remove the added organic binder and inherent structural water, respectively.2.2. CharacterizationThe chemical compositions of calcined coal gangue and bauxite were characterized by quantitative X-ray fluorescence spectrum analysis (Axios-Advanced, PANalytical Corporation, Netherlands). The particle size distributions of coal gangue and bauxite were determined by a laser particle size analyzer (Mastersizer 2000, Malvern Instruments Ltd., UK) using water as dispersing medium. X-ray diffraction (XRD, X ’Pert Pro, PANalytical Corpora -tion, Netherlands) was used to characterize the phase compositions of the starting materials and the phase assemblage of the mullite ceramic membrane supports sintered from 1100 to 1400 ◦C for 2 h. Reference intensity ratio (RIR)-quantitative analysis was employed to determine the phase contents.The morphology of the raw materials (coal gangue and bauxite) and the fracture surfaces of the mullite ceramic membrane sup-ports were observed using scanning electronic microscope (SEM, S-4800, Hitachi Ltd., Japan). Before SEM observation, some of the samples were etched with 15 vol.% HF solution for 30 min and then dried at 90 ◦C for 10 h. The dynamic sintering shrinkage behavior of the green rectangular bar of the mullite ceramic membrane support was measured between room temperature and 1500 ◦C in a hori-zontal dilatometer (Netzsch DIL 402 C, Netzsch-Gerätebau GmbH, Germany) at a heating rate of 10 ◦C min −1. The linear shrinkage percents in diameter direction of the sintered pellets were mea-sured using a vernier caliper. Open porosity and bulk density were measured in water medium according to the Archimedes ’ princi -ple. Pore size distribution and nitrogen gas permeation flux of the mullite ceramic membrane supports sintered at various tempera-tures were measured by a pore size distribution analyzer (PSDA-20, Nanjing Gaoqian function materials Co. Ltd., China). The pore diam-eter was calculated from the Washburn ’s eq uation according to bubble-point method:d =4 cos (1)Pwhere d is the pore diameter, is the surface tension of wetting liquid, is the contact angle between the wetting liq-uid and the testing material, and P is the applied pressure difference [28].Biaxial flexural strength (BFS) tests were performed using a uni-versal testing machine (AGS-X, Shimadzu Corporation Ltd., Japan) according to ISO6872 on disc specimens (diameter: 15–17 mm; thickness: 0.70–0.85 mm). A crosshead speed of 0.1 mm min −1and a preload of 5 N were utilized along with a test jig (lab-designed) with a support radius of 5 mm [29,30]. Finally, biaxial flexural strengths were calculated from the recorded maximum loads at fracture using the following equation given by Timmoschenko and Woinowsky-Kreiger [31],SS(MPa) = P(1 + v ) 0.485 ln a+ 0.52 + 0.48 (2) t 2 t where SS is the flexural strength (MPa), P is the maximum load (N), r is the radius of three-ball support circle (mm), v is Pois-son ’s ratio (here v = 0.257 for mullite-based materials), and t is the138Q. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145Fig. 1. XRD patterns of (a) calcined coal gangue and (b) calcined bauxite.thickness of the samples (mm). Weibull analysis was carried out on the results of BFS to measure the reliability. The Weibull analysis curves were made using ln and ln ln[1/(1 − P f )] plot as X-axis and Y-axis, respectively, where is the BFS and P f is the fracture prob-ability. The latter P f is defined by the relation P f = i/(N + 1), where i is the rank in BFS from smallest to largest and N is the total num-ber of the samples (here N = 10 in our study) at specific parameters [32,33].3. Results and discussion3.1. Characterization of starting materials3.1.1. Chemical compositionTable 1 lists the chemical compositions of calcined coal gangue and bauxite characterized by quantitative X-ray fluorescence spec-trum analysis. The majority of coal gangue used in this study mainly consists of SiO 2 (70.08 wt.%) and Al 2 O 3 (17.36 wt.%). There are also small amount of co-existing alkali and alkaline –earth metal oxides such as MgO, Na 2 O, CaO, K 2 O, etc, and transition metal oxides (0.99 wt.% TiO 2 and 5.94 wt.% Fe 2 O 3 ) in coal gangue. Bauxite is mainly composed of Al 2 O 3 (84.97 wt.%). Besides, there is a certain amount of SiO 2 (7.36 wt.%) and TiO 2 (4.57 wt.%) in bauxite. To syn-thesize 3:2 mullite, the mass ratio of coal gangue to bauxite was calculated according to the results of XRF.3.1.2. Phase compositionThe XRD patterns of calcined coal gangue and bauxite are shown in Fig. 1. As shown in Fig. 1a, the crystalline phases detected in coal gangue are quartz as major phase (SiO 2 , hexagonal system, PDF# 850797) and potassium mica as minor one (KAl 3 Si 3 O 11 , monoclinic system, PDF# 460741). Fig. 1b presents that calcined bauxite mainly consists of corundum (Al 2 O 3 , hexagonal system, PDF# 880826) as major phase, mullite (3Al 2 O 3 –2SiO 2 , orthorhombic system, PDF# 791455) and rutile (TiO 2 , tetragonal system, PDF# 340180) as minor phases. This mullite phase is considered to be primary mullite which came from the minerals containing Al and Si, dur-ing the calcination of natural bauxite. In our previous study [18], the main phases of natural bauxite including diaspore (AlO(OH),Fig. 2. SEM images of (a) coal gangue and (b) bauxite, (c) particle size distribution of coal gangue, bauxite, and their mixture after ball milling.Q. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145 139Table 1Chemical composition (wt.%) of the raw materials measured by quantitative XRF.MaterialsChemical composition (wt.%)Al 2 O 3SiO 2TiO 2Fe 2 O 3MgONa 2 OCaOK 2 OZrO 2OthersCoal gangue 17.36 70.08 0.99 5.94 0.94 0.36 0.26 3.21 0.09 0.79Bauxite 84.98 7.36 4.57 1.27 – 0.16 0.27 0.52 0.10 0.79The loss on ignition of coal gangue and bauxite is 0.03 and 0.12%, respectively.Fig. 3. Linear shrinkage percent (dL/L 0 ) and differential linear shrinkage percent (dL/dt) between room temperature and 1500 ◦C of the green rectangular of the mul-liteceramic membrane support. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)orthorhombic system, PDF# 050355), kaolinite (Al 2 O 3 ·2SiO 2 ·2H 2 O, anorthic system, PDF# 030059) and quartz (SiO 2 , hexagonal sys-tem, PDF# 850797) transferred into corundum and mullite after high-temperature calcination.3.1.3. SEM and particle size distributionFig. 2 shows the SEM images of coal gangue and bauxite, and the particle size distribution of coal gangue, bauxite and their mix-ture after ball milling. Coal gangue is lamellar in morphology and its particle size distribution is relatively narrow (Fig. 2a). Bauxite is morphologically blocky and its particle size distribution is wider (Fig. 2b). Fig. 2c gives the particle size distributions of coal gangue, bauxite and their mixture after ball milling. It can be observed that the particle size of coal gangue ranges from 1 to 5 m with an aver-age value (D 50 ) of 2.96 m and the particle size of bauxite ranges from 0.2 to 80 m with an average value (D 50 ) of 19.17 m. Their mixture after ball milling ranges from 1 to 10 m with an aver-age value (D 50 ) of 5.14 m. The results of particle size analysis are consistent with SEM observation.3.2. Sintering and pore-structure3.2.1. Sintering behaviorDilatometric study was employed to measure the sintering behaviors of the green body of the mullite ceramic membrane support. Fig. 3 presents the linear shrinkage percent (dL/L 0 ) and dif-ferential linear shrinkage percent (dL/dt) of the green rectangular bar of the mullite ceramic membrane support. At high tempera-tures (above 800 ◦C), the process can be divided into three stages. Initially, a significant sintering shrinkage is observed at increased temperature from 969 ◦C to 1276 ◦C, where there is a maximum shrinkage of 2.25% at 1276 ◦ C. In the second stage, a volume-expansion stage (1.06%) is observed at increasing temperaturefrom 1276 to 1481 ◦C. During this process, secondary mullitiza-tion occurred, followed by anisotropic growth of mullite crystals, which caused this unique volume-expansion with increasing tem-perature, not normally observed gradual densification. To further study this mullitization-crystal-growth process, the phase evolu-tion and the growth of mullite crystals will be discussed in detail in Sections 3.2.2 and 3.3.1, respectively. The volume expansion caused by this mullitization-crystal-growth process was also mentioned in fly-ash –bauxite system in our previous study, where the self-expansion stage was from 1326 to 1477 ◦C [13]. In the third stage, above 1481 ◦C, the sample shrunk again as a result of densification.3.2.2. Phase evolutionFig. 4 illustrates the phase assemblage and the crystalline phase contents (calculated by RIR-quantitative analysis) of the mulliteceramic membrane supports sintered from 1100 to 1400 ◦ C. At 1100 ◦C, the major phase is corundum and the weak diffraction peaks of mullite and quartz are observed. The contents of mullite, corundumand quartz are 17.0, 69.7, and 13.4 wt.%, respectively. At 1200 ◦C, the diffraction peak intensity of mullite increases signifi-cantly with a mullitecontent of 51.5 wt.%, while the peaks of quartz disappear. From 1200 ◦C to 1400 ◦C, the peak intensity of mullite phase increases gradually, with mullite content increasing from 51.5 to 84.7 wt.%. Meanwhile, the diffraction peaks of corundum become weak. It indicates thatsecondary mullitization occurred significantly from 1100 to 1200 ◦C, gradually enhanced from 1200 to 1400 ◦C. During synthesis of kaolin-based mullite, secondary mullitization is also observed during 1300–1600 ◦ C [21–23].Nevertheless, in this work the diffraction peaks of corundum are stillobserved even after sintering at 1400 ◦C. It is probably because the alumina in calcined bauxite is of low reaction activity, resulting in a longer dynamic reaction diffusion path between bauxite-derived alumina and coal-gangue-derived silica [13]. Some studies show that the alumina derived from different sources presented different activities. Li et al. reported that the sample fabricated from Al(OH)3 had a higher mullitization degree than other samples due to the higher activity of Al 2 O 3 that came from the decomposition of Al(OH)3 than that of exotic Al 2 O 3 [34].3.2.3. Shrinkage, bulk density and open porosityFig. 5 shows the linear shrinkage percent and bulk density of mullite ceramic membrane supports after sintering at tempera-tures from 1100 to 1500 ◦C. From 1100 to 1200 ◦C, the sample exhibits a general sintering shrinkage characteristic, accompanying with a gradual increase in both shrinkage percent and bulk den-sity. However, with sintering temperature increasing from 1200 to 1350 ◦C, the shrinkage percent and bulk density decrease grad-ually from 3.28 ± 0.05 to 1.93 ± 0.10% and from 2.45 ± 0.01 to 2.34 ± 0.01 g cm −3 , respectively. It suggests that the abnormal vol-ume expansion occurred in this temperature range due to the mullitization-crystal-growth process. However the temperature range is different from that mentioned in Section 3.2.1 (1276 to 1481 ◦C) which is mainly due to the difference of heating process. Between 1350 and 1450 ◦C, the relatively slow densification rate indicates the effect of this volume expansion still exists, but weaker than that of sintering-induced densification. When sintering tem-perature is higher than 1450 ◦ C, shrinkage percent and bulk density140Q. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145Fig. 4. (a) XRD patterns of the mullite ceramic membrane supports sintered at various temperatures and (b) contents of crystalline phases.significantly increase during the high-temperature densificationprocess. At 1500 ◦C, the shrinkage and bulk density are 5.00 ± 0.12% and 2.61 ± 0.01 g cm −3, respectively.Fig. 6 shows the open porosity of ceramic membrane supports without and with corn starch addition. As shown in Fig. 6a, open porosity firstly decreases with increasing temperature from 1100 to 1250 ◦C, then increases in the range of 1250–1350 ◦C, and finally decreases again from 1350 to 1500 ◦C. This result is consistent with that deduced from linear shrinkage percent and bulk density curves (shown in Fig. 5). The enhancement of open porosity at elevated temperatures (1250–1350 ◦C) is also observed in fly-ash –bauxite system, but the kaolin –alumina system [22] exhibits the different result that a gradual decrease in open porosity (a gradual increase in bulk density and shrinkage) at elevated temperature is presented.For ceramic membrane support, low open porosity (less than 30%) is not sufficient to be used for the purpose of filtration. To enhance open porosity, commercial corn starch was used as pore-forming agent. Fig. 6b displays the open porosity of the samples with addition of different contents of corn starch after sintering at 1350 ◦C. As can be seen, open porosity is remarkably increased with increasing corn starch content, accompanied with a grad-ual decrease in bulk density but a gradual increase in shrinkage percent (the inset in Fig. 6b). High open porosities (39.67 ± 0.21%, 45.00 ± 0.56% and 48.12 ± 0.23% for 16 wt.%, 24 wt.%, and 32 wt.% corn starch addition, respectively) are obtained.Fig. 5. Linear shrinkage percent and bulk density of the mullite ceramic membrane supports sintered at various temperatures.3.2.4. Pore size distributionThe pore size distribution of the mullite ceramic membrane sup-ports without and with corn starch addition is presented in Fig. 7. As presented in Fig. 7a, sintering temperature has a significant effect on pore size. When sintering temperature rises from 1200 to 1350 ◦C, the pores distribution curves slightly shift to the direction of small pores, while average pore size decreases. The average pore size increases with sintering temperature further rising from 1350 to 1500 ◦ C, because high-temperature sintering made the small pores connected with each other and consequently larger pores are formed at higher temperatures.Fig. 7b shows the pore size distribution of the mullite ceramic membrane supports after adding corn starch. With the increase of corn starch content, the pore size distribution curves move to the direction of large pores and the pore size distributions become broad. Average pore diameters are 0.27, 0.65, 1.81, 1.96 and 2.64 m at 0 wt.%, 8 wt.%, 16 wt.%, 24 wt.% and 32 wt.% corn-starch contents, respectively. The microstructure changes in pore size by adding pore-forming agent will be shown in the SEM images in Section 3.3.1.3.2.5. Nitrogen gas fluxFig. 8 displays the nitrogen gas flux under various applied trans-membrane pressures of the mullite ceramic membrane supports without corn starch addition. At all the applied trans-membranepressures, from 1200 to 1300 ◦C, the nitrogen gas flux slightly decreases, and then increases from 1300 to 1400 ◦C. At 1400 ◦C, the nitrogen gas flux has a maximum value of 5.84 × 103m 3m 2 h −1at 0.4 MPa, which is due to a high open porosity as shown in Fig. 6a andlarge average pore size as shown in Fig. 7a. From 1400 to 1500 ◦C, the nitrogen gas flux decreases due to the porosity reduc-tion resulted from high-temperature densification [13,18,21].3.3. Microstructure and mechanical property3.3.1. MicrostructureFig. 9 shows the SEM images of fracture surfaces of the mul-lite ceramic membrane supports sintered at different temperatures before and after 15 wt.% HF solution etching for 30 min. With sin-tering temperature increasing from 1200 to 1350 ◦C, the amount of pores slightly increases. This verifies the enhancement in open porosity from 1200 to 1350 ◦C as shown in Fig. 6a. From 1350 to 1500 ◦C (Fig. 9e), the pore size increases significantly, while the amount of pores decreases. It is consistent with the increase of pore size (Fig. 7a) which is caused by the formation of large poresQ. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145 141Fig. 6. Open porosity of the mullite ceramic membrane supports: (a) without corn starch addition after sintering at 1100–1500 ◦C, and (b) with addition of various contents of corn starch after sintering at 1350 ◦C. The inset in Fig. 6b shows shrinkage and bulk density of the mullite ceramic membrane supports with addition of various contents of corn starch after sintering at 1350 ◦C.Fig. 7. Pore size distribution of the mullite ceramic membrane supports (a) without corn starch addition sintered at various temperatures for 2 h, (b) with various corn starch contents sintered at 1350 ◦C.due to the sintering-induced combination of fine pores during the high-temperature densification.Fig. 9b, d and f shows the morphologies of mullite crystals in the mullite membrane supports after HF etching for 30 min. Due to the removal of aluminosilicate glassy phase, rod-like secondary mul-lite crystals are observed at 1200 ◦C (Fig. 9b). From 1200 to 1500 ◦C, the mullite crystals grew significantly in size and the morpholo-gies become rectangular block-like at 1500 ◦C (Fig. 9f). The average aspect ratios of the mullite crystals at 1200, 1350 and 1500 ◦C are calculated to be 8.50, 7.30 and 4.29, respectively. It clearly indicates that mullite crystals gradually grow up with increasing sintering temperature. In Fig. 9f, the bonding between mullite crystals which effectively enhances the mechanical strength of the mullite ceramic membrane supports is indicated using red arrows.Fig. 10 displays the fracture microstructures of the mullite ceramic membrane supports with different corn starch additions (16 wt.% and 32 wt.%) sintered at 1350 ◦C. Compared with Fig. 9c (without corn starch), the addition of 16 wt.% and 32 wt.% corn starch resulted in an improvement both in porous-structure with more large pore (Fig. 10a and b) and in open porosity due to the combustion of corn starch with large size. Those are consistent with the results in Figs. 6b and 7b.Fig. 8. Nitrogen gas flux with different applied trans-membrane pressures of the mullite ceramic membrane supports sintered at various temperatures.142Q. Lü et al. / Journal of Hazardous Materials 273 (2014) 136–145Fig. 9. SEM images of fracture surfaces of the mullite ceramic membrane supports sintered at different temperatures before (a, c, e) and after (b, d, f) 15 wt.% HF solution etching for 30 min.3.3.2. Biaxial flexural strengthFig. 11 displays the results of biaxial flexural strength tests of the mullite ceramic membrane supports. Fig. 11a shows the typical load –deflection curves. All the curves correspond to the specimens with strength around the statistical average values. For all the samples, a nonlinear monotonic relationship between load and deflection can be clearly seen before the maximum load. This is then followed by a complete load degradation to zero over a further deflection stage at lower load than the max-imum (except for the sample sintered at 1500◦C), as is normal for brittle ceramics with porous structure. Fig. 11b shows the BFS of the mullite ceramic membrane supports sintered at each temperature. Similar to the result of linear shrinkage percent, the BFS-temperature curve is also divided into three stages: (i) BFS increases with temperature at 1200–1250 ◦C; (ii) BSF decreaseswith temperature at 1250–1350 ◦C; and (iii) BSF increases withtemperature at 1350–1500 ◦C. During the second stage, from 1250 to1350 ◦C, a decrease in mechanical strength is attributed to the enhancement of open porosity caused by the mullitization-crystal-growth process. The variation trend of this BFS-temperature curve is different from those of fly ash –bauxite system [13] and kaolin –Al 2 O 3 system [22] which continuously increase at elevated sintering temperatures. Fig. 11c presents the Weibull analysis of BFS results of the mullite ceramic membrane supports sintered between 1200 and1500 ◦ C with an interval of 100 ◦C. Most of the points (ln vs. ln ln[1/(1 − P f )]) center close to the corresponding fitted lines, which proves the reliability of the BFS results.Fig. 12 presents the results of biaxial flexural strength tests of the mullite ceramic membrane supports with various corn starch contents after sintering at 1350 ◦C. Fig. 12a shows the。
微生物英文文献及翻译—原文
Dynamic and distribution of ammonia-oxidizing bacteria communities during sludge granulation in an anaerobic e aerobic sequencing batch reactorZhang Bin a ,b ,Chen Zhe a ,b ,Qiu Zhigang a ,b ,Jin Min a ,b ,Chen Zhiqiang a ,b ,Chen Zhaoli a ,b ,Li Junwen a ,b ,Wang Xuan c ,*,Wang Jingfeng a ,b ,**aInstitute of Hygiene and Environmental Medicine,Academy of Military Medical Sciences,Tianjin 300050,PR China bTianjin Key Laboratory of Risk Assessment and Control for Environment and Food Safety,Tianjin 300050,PR China cTianjin Key Laboratory of Hollow Fiber Membrane Material and Membrane Process,Institute of Biological and Chemical Engineering,Tianjin Polytechnical University,Tianjin 300160,PR Chinaa r t i c l e i n f oArticle history:Received 30June 2011Received in revised form 10September 2011Accepted 10September 2011Available online xxx Keywords:Ammonia-oxidizing bacteria Granular sludgeCommunity development Granule sizeNitrifying bacteria distribution Phylogenetic diversitya b s t r a c tThe structure dynamic of ammonia-oxidizing bacteria (AOB)community and the distribution of AOB and nitrite-oxidizing bacteria (NOB)in granular sludge from an anaerobic e aerobic sequencing batch reactor (SBR)were investigated.A combination of process studies,molecular biotechniques and microscale techniques were employed to identify and characterize these organisms.The AOB community structure in granules was substantially different from that of the initial pattern of the inoculants sludge.Along with granules formation,the AOB diversity declined due to the selection pressure imposed by process conditions.Denaturing gradient gel electrophoresis (DGGE)and sequencing results demonstrated that most of Nitrosomonas in the inoculating sludge were remained because of their ability to rapidly adapt to the settling e washing out action.Furthermore,DGGE analysis revealed that larger granules benefit more AOB species surviving in the reactor.In the SBR were various size granules coexisted,granule diameter affected the distribution range of AOB and NOB.Small and medium granules (d <0.6mm)cannot restrict oxygen mass transfer in all spaces of the rger granules (d >0.9mm)can result in smaller aerobic volume fraction and inhibition of NOB growth.All these observations provide support to future studies on the mechanisms responsible for the AOB in granules systems.ª2011Elsevier Ltd.All rights reserved.1.IntroductionAt sufficiently high levels,ammonia in aquatic environments can be toxic to aquatic life and can contribute to eutrophica-tion.Accordingly,biodegradation and elimination of ammonia in wastewater are the primary functions of thewastewater treatment process.Nitrification,the conversion of ammonia to nitrate via nitrite,is an important way to remove ammonia nitrogen.It is a two-step process catalyzed by ammonia-oxidizing and nitrite-oxidizing bacteria (AOB and NOB).Aerobic ammonia-oxidation is often the first,rate-limiting step of nitrification;however,it is essential for the*Corresponding author .**Corresponding author.Institute of Hygiene and Environmental Medicine,Academy of Military Medical Sciences,Tianjin 300050,PR China.Tel.:+862284655498;fax:+862223328809.E-mail addresses:wangxuan0116@ (W.Xuan),jingfengwang@ (W.Jingfeng).Available online atjournal homepage:/locate/watresw a t e r r e s e a r c h x x x (2011)1e 100043-1354/$e see front matter ª2011Elsevier Ltd.All rights reserved.doi:10.1016/j.watres.2011.09.026removal of ammonia from the wastewater(Prosser and Nicol, 2008).Comparative analyses of16S rRNA sequences have revealed that most AOB in activated sludge are phylogeneti-cally closely related to the clade of b-Proteobacteria (Kowalchuk and Stephen,2001).However,a number of studies have suggested that there are physiological and ecological differences between different AOB genera and lineages,and that environmental factors such as process parameter,dis-solved oxygen,salinity,pH,and concentrations of free ammonia can impact certain species of AOB(Erguder et al., 2008;Kim et al.,2006;Koops and Pommerening-Ro¨ser,2001; Kowalchuk and Stephen,2001;Shi et al.,2010).Therefore, the physiological activity and abundance of AOB in waste-water processing is critical in the design and operation of waste treatment systems.For this reason,a better under-standing of the ecology and microbiology of AOB in waste-water treatment systems is necessary to enhance treatment performance.Recently,several developed techniques have served as valuable tools for the characterization of microbial diversity in biological wastewater treatment systems(Li et al., 2008;Yin and Xu,2009).Currently,the application of molec-ular biotechniques can provide clarification of the ammonia-oxidizing community in detail(Haseborg et al.,2010;Tawan et al.,2005;Vlaeminck et al.,2010).In recent years,the aerobic granular sludge process has become an attractive alternative to conventional processes for wastewater treatment mainly due to its cell immobilization strategy(de Bruin et al.,2004;Liu et al.,2009;Schwarzenbeck et al.,2005;Schwarzenbeck et al.,2004a,b;Xavier et al.,2007). Granules have a more tightly compact structure(Li et al.,2008; Liu and Tay,2008;Wang et al.,2004)and rapid settling velocity (Kong et al.,2009;Lemaire et al.,2008).Therefore,granular sludge systems have a higher mixed liquid suspended sludge (MLSS)concentration and longer solid retention times(SRT) than conventional activated sludge systems.Longer SRT can provide enough time for the growth of organisms that require a long generation time(e.g.,AOB).Some studies have indicated that nitrifying granules can be cultivated with ammonia-rich inorganic wastewater and the diameter of granules was small (Shi et al.,2010;Tsuneda et al.,2003).Other researchers reported that larger granules have been developed with the synthetic organic wastewater in sequencing batch reactors(SBRs)(Li et al., 2008;Liu and Tay,2008).The diverse populations of microor-ganisms that coexist in granules remove the chemical oxygen demand(COD),nitrogen and phosphate(de Kreuk et al.,2005). However,for larger granules with a particle diameter greater than0.6mm,an outer aerobic shell and an inner anaerobic zone coexist because of restricted oxygen diffusion to the granule core.These properties of granular sludge suggest that the inner environment of granules is unfavorable to AOB growth.Some research has shown that particle size and density induced the different distribution and dominance of AOB,NOB and anam-mox(Winkler et al.,2011b).Although a number of studies have been conducted to assess the ecology and microbiology of AOB in wastewater treatment systems,the information on the dynamics,distribution,and quantification of AOB communities during sludge granulation is still limited up to now.To address these concerns,the main objective of the present work was to investigate the population dynamics of AOB communities during the development of seedingflocs into granules,and the distribution of AOB and NOB in different size granules from an anaerobic e aerobic SBR.A combination of process studies,molecular biotechniques and microscale techniques were employed to identify and char-acterize these organisms.Based on these approaches,we demonstrate the differences in both AOB community evolu-tion and composition of theflocs and granules co-existing in the SBR and further elucidate the relationship between distribution of nitrifying bacteria and granule size.It is ex-pected that the work would be useful to better understand the mechanisms responsible for the AOB in granules and apply them for optimal control and management strategies of granulation systems.2.Material and methods2.1.Reactor set-up and operationThe granules were cultivated in a lab-scale SBR with an effective volume of4L.The effective diameter and height of the reactor was10cm and51cm,respectively.The hydraulic retention time was set at8h.Activated sludge from a full-scale sewage treat-ment plant(Jizhuangzi Sewage Treatment Works,Tianjin, China)was used as the seed sludge for the reactor at an initial sludge concentration of3876mg LÀ1in MLSS.The reactor was operated on6-h cycles,consisting of2-min influent feeding,90-min anaerobic phase(mixing),240-min aeration phase and5-min effluent discharge periods.The sludge settling time was reduced gradually from10to5min after80SBR cycles in20days, and only particles with a settling velocity higher than4.5m hÀ1 were retained in the reactor.The composition of the influent media were NaAc(450mg LÀ1),NH4Cl(100mg LÀ1),(NH4)2SO4 (10mg LÀ1),KH2PO4(20mg LÀ1),MgSO4$7H2O(50mg LÀ1),KCl (20mg LÀ1),CaCl2(20mg LÀ1),FeSO4$7H2O(1mg LÀ1),pH7.0e7.5, and0.1mL LÀ1trace element solution(Li et al.,2007).Analytical methods-The total organic carbon(TOC),NHþ4e N, NOÀ2e N,NOÀ3e N,total nitrogen(TN),total phosphate(TP) concentration,mixed liquid suspended solids(MLSS) concentration,and sludge volume index at10min(SVI10)were measured regularly according to the standard methods (APHA-AWWA-WEF,2005).Sludge size distribution was determined by the sieving method(Laguna et al.,1999).Screening was performed with four stainless steel sieves of5cm diameter having respective mesh openings of0.9,0.6,0.45,and0.2mm.A100mL volume of sludge from the reactor was sampled with a calibrated cylinder and then deposited on the0.9mm mesh sieve.The sample was subsequently washed with distilled water and particles less than0.9mm in diameter passed through this sieve to the sieves with smaller openings.The washing procedure was repeated several times to separate the gran-ules.The granules collected on the different screens were recovered by backwashing with distilled water.Each fraction was collected in a different beaker andfiltered on quantitative filter paper to determine the total suspended solid(TSS).Once the amount of total suspended solid(TSS)retained on each sieve was acquired,it was reasonable to determine for each class of size(<0.2,[0.2e0.45],[0.45e0.6],[0.6e0.9],>0.9mm) the percentage of the total weight that they represent.w a t e r r e s e a r c h x x x(2011)1e10 22.2.DNA extraction and nested PCR e DGGEThe sludge from approximately8mg of MLSS was transferred into a1.5-mL Eppendorf tube and then centrifuged at14,000g for10min.The supernatant was removed,and the pellet was added to1mL of sodium phosphate buffer solution and aseptically mixed with a sterilized pestle in order to detach granules.Genomic DNA was extracted from the pellets using E.Z.N.A.äSoil DNA kit(D5625-01,Omega Bio-tek Inc.,USA).To amplify ammonia-oxidizer specific16S rRNA for dena-turing gradient gel electrophoresis(DGGE),a nested PCR approach was performed as described previously(Zhang et al., 2010).30m l of nested PCR amplicons(with5m l6Âloading buffer)were loaded and separated by DGGE on polyacrylamide gels(8%,37.5:1acrylamide e bisacrylamide)with a linear gradient of35%e55%denaturant(100%denaturant¼7M urea plus40%formamide).The gel was run for6.5h at140V in 1ÂTAE buffer(40mM Tris-acetate,20mM sodium acetate, 1mM Na2EDTA,pH7.4)maintained at60 C(DCodeäUniversal Mutation Detection System,Bio-Rad,Hercules,CA, USA).After electrophoresis,silver-staining and development of the gels were performed as described by Sanguinetti et al. (1994).These were followed by air-drying and scanning with a gel imaging analysis system(Image Quant350,GE Inc.,USA). The gel images were analyzed with the software Quantity One,version4.31(Bio-rad).Dice index(Cs)of pair wise community similarity was calculated to evaluate the similarity of the AOB community among DGGE lanes(LaPara et al.,2002).This index ranges from0%(no common band)to100%(identical band patterns) with the assistance of Quantity One.The Shannon diversity index(H)was used to measure the microbial diversity that takes into account the richness and proportion of each species in a population.H was calculatedusing the following equation:H¼ÀPn iNlogn iN,where n i/Nis the proportion of community made up by species i(bright-ness of the band i/total brightness of all bands in the lane).Dendrograms relating band pattern similarities were automatically calculated without band weighting(consider-ation of band density)by the unweighted pair group method with arithmetic mean(UPGMA)algorithms in the Quantity One software.Prominent DGGE bands were excised and dissolved in30m L Milli-Q water overnight,at4 C.DNA was recovered from the gel by freeze e thawing thrice.Cloning and sequencing of the target DNA fragments were conducted following the estab-lished method(Zhang et al.,2010).2.3.Distribution of nitrifying bacteriaThree classes of size([0.2e0.45],[0.45e0.6],>0.9mm)were chosen on day180for FISH analysis in order to investigate the spatial distribution characteristics of AOB and NOB in granules.2mg sludge samples werefixed in4%para-formaldehyde solution for16e24h at4 C and then washed twice with sodium phosphate buffer;the samples were dehydrated in50%,80%and100%ethanol for10min each. Ethanol in the granules was then completely replaced by xylene by serial immersion in ethanol-xylene solutions of3:1, 1:1,and1:3by volume andfinally in100%xylene,for10min periods at room temperature.Subsequently,the granules were embedded in paraffin(m.p.56e58 C)by serial immer-sion in1:1xylene-paraffin for30min at60 C,followed by 100%paraffin.After solidification in paraffin,8-m m-thick sections were prepared and placed on gelatin-coated micro-scopic slides.Paraffin was removed by immersing the slide in xylene and ethanol for30min each,followed by air-drying of the slides.The three oligonucleotide probes were used for hybridiza-tion(Downing and Nerenberg,2008):FITC-labeled Nso190, which targets the majority of AOB;TRITC-labeled NIT3,which targets Nitrobacter sp.;TRITC-labeled NSR1156,which targets Nitrospira sp.All probe sequences,their hybridization condi-tions,and washing conditions are given in Table1.Oligonu-cleotides were synthesized andfluorescently labeled with fluorochomes by Takara,Inc.(Dalian,China).Hybridizations were performed at46 C for2h with a hybridization buffer(0.9M NaCl,formamide at the percentage shown in Table1,20mM Tris/HCl,pH8.0,0.01% SDS)containing each labeled probe(5ng m LÀ1).After hybrid-ization,unbound oligonucleotides were removed by a strin-gent washing step at48 C for15min in washing buffer containing the same components as the hybridization buffer except for the probes.For detection of all DNA,4,6-diamidino-2-phenylindole (DAPI)was diluted with methanol to afinal concentration of1ng m LÀ1.Cover the slides with DAPI e methanol and incubate for15min at37 C.The slides were subsequently washed once with methanol,rinsed briefly with ddH2O and immediately air-dried.Vectashield(Vector Laboratories)was used to prevent photo bleaching.The hybridization images were captured using a confocal laser scanning microscope (CLSM,Zeiss710).A total of10images were captured for each probe at each class of size.The representative images were selected andfinal image evaluation was done in Adobe PhotoShop.w a t e r r e s e a r c h x x x(2011)1e1033.Results3.1.SBR performance and granule characteristicsDuring the startup period,the reactor removed TOC and NH 4þ-N efficiently.98%of NH 4þ-N and 100%of TOC were removed from the influent by day 3and day 5respectively (Figs.S2,S3,Supporting information ).Removal of TN and TP were lower during this period (Figs.S3,S4,Supporting information ),though the removal of TP gradually improved to 100%removal by day 33(Fig.S4,Supporting information ).To determine the sludge volume index of granular sludge,a settling time of 10min was chosen instead of 30min,because granular sludge has a similar SVI after 60min and after 5min of settling (Schwarzenbeck et al.,2004b ).The SVI 10of the inoculating sludge was 108.2mL g À1.The changing patterns of MLSS and SVI 10in the continuous operation of the SBR are illustrated in Fig.1.The sludge settleability increased markedly during the set-up period.Fig.2reflects the slow andgradual process of sludge granulation,i.e.,from flocculentsludge to granules.3.2.DGGE analysis:AOB communities structure changes during sludge granulationThe results of nested PCR were shown in Fig.S1.The well-resolved DGGE bands were obtained at the representative points throughout the GSBR operation and the patterns revealed that the structure of the AOB communities was dynamic during sludge granulation and stabilization (Fig.3).The community structure at the end of experiment was different from that of the initial pattern of the seed sludge.The AOB communities on day 1showed 40%similarity only to that at the end of the GSBR operation (Table S1,Supporting information ),indicating the considerable difference of AOB communities structures between inoculated sludge and granular sludge.Biodiversity based on the DGGE patterns was analyzed by calculating the Shannon diversity index H as204060801001201401254159738494104115125135147160172188Time (d)S V I 10 (m L .g -1)10002000300040005000600070008000900010000M L S S (m g .L -1)Fig.1e Change in biomass content and SVI 10during whole operation.SVI,sludge volume index;MLSS,mixed liquid suspendedsolids.Fig.2e Variation in granule size distribution in the sludge during operation.d,particle diameter;TSS,total suspended solids.w a t e r r e s e a r c h x x x (2011)1e 104shown in Fig.S5.In the phase of sludge inoculation (before day 38),H decreased remarkably (from 0.94to 0.75)due to the absence of some species in the reactor.Though several dominant species (bands2,7,10,11)in the inoculating sludge were preserved,many bands disappeared or weakened (bands 3,4,6,8,13,14,15).After day 45,the diversity index tended to be stable and showed small fluctuation (from 0.72to 0.82).Banding pattern similarity was analyzed by applying UPGMA (Fig.4)algorithms.The UPGMA analysis showed three groups with intragroup similarity at approximately 67%e 78%and intergroup similarity at 44e 62%.Generally,the clustering followed the time course;and the algorithms showed a closer clustering of groups II and III.In the analysis,group I was associated with sludge inoculation and washout,group IIwithFig.3e DGGE profile of the AOB communities in the SBR during the sludge granulation process (lane labels along the top show the sampling time (days)from startup of the bioreactor).The major bands were labeled with the numbers (bands 1e15).Fig.4e UPGMA analysis dendrograms of AOB community DGGE banding patterns,showing schematics of banding patterns.Roman numerals indicate major clusters.w a t e r r e s e a r c h x x x (2011)1e 105startup sludge granulation and decreasing SVI 10,and group III with a stable system and excellent biomass settleability.In Fig.3,the locations of the predominant bands were excised from the gel.DNA in these bands were reamplified,cloned and sequenced.The comparative analysis of these partial 16S rRNA sequences (Table 2and Fig.S6)revealed the phylogenetic affiliation of 13sequences retrieved.The majority of the bacteria in seed sludge grouped with members of Nitrosomonas and Nitrosospira .Along with sludge granula-tion,most of Nitrosomonas (Bands 2,5,7,9,10,11)were remained or eventually became dominant in GSBR;however,all of Nitrosospira (Bands 6,13,15)were gradually eliminated from the reactor.3.3.Distribution of AOB and NOB in different sized granulesFISH was performed on the granule sections mainly to deter-mine the location of AOB and NOB within the different size classes of granules,and the images were not further analyzed for quantification of cell counts.As shown in Fig.6,in small granules (0.2mm <d <0.45mm),AOB located mainly in the outer part of granular space,whereas NOB were detected only in the core of granules.In medium granules (0.45mm <d <0.6mm),AOB distributed evenly throughout the whole granular space,whereas NOB still existed in the inner part.In the larger granules (d >0.9mm),AOB and NOB were mostly located in the surface area of the granules,and moreover,NOB became rare.4.Discussion4.1.Relationship between granule formation and reactor performanceAfter day 32,the SVI 10stabilized at 20e 35mL g À1,which is very low compared to the values measured for activated sludge (100e 150mL g À1).However,the size distribution of the granules measured on day 32(Fig.2)indicated that only 22%of the biomass was made of granular sludge with diameter largerthan 0.2mm.These results suggest that sludge settleability increased prior to granule formation and was not affected by different particle sizes in the sludge during the GSBR operation.It was observed,however,that the diameter of the granules fluctuated over longer durations.The large granules tended to destabilize due to endogenous respiration,and broke into smaller granules that could seed the formation of large granules again.Pochana and Keller reported that physically broken sludge flocs contribute to lower denitrification rates,due to their reduced anoxic zone (Pochana and Keller,1999).Therefore,TN removal efficiency raises fluctuantly throughout the experiment.Some previous research had demonstrated that bigger,more dense granules favored the enrichment of PAO (Winkler et al.,2011a ).Hence,after day 77,removal efficiency of TP was higher and relatively stable because the granules mass fraction was over 90%and more larger granules formed.4.2.Relationship between AOB communities dynamic and sludge granulationFor granule formation,a short settling time was set,and only particles with a settling velocity higher than 4.5m h À1were retained in the reactor.Moreover,as shown in Fig.1,the variation in SVI 10was greater before day 41(from 108.2mL g À1e 34.1mL g À1).During this phase,large amounts of biomass could not survive in the reactor.A clear shift in pop-ulations was evident,with 58%similarity between days 8and 18(Table S1).In the SBR system fed with acetate-based synthetic wastewater,heterotrophic bacteria can produce much larger amounts of extracellular polysaccharides than autotrophic bacteria (Tsuneda et al.,2003).Some researchers found that microorganisms in high shear environments adhered by extracellular polymeric substances (EPS)to resist the damage of suspended cells by environmental forces (Trinet et al.,1991).Additionally,it had been proved that the dominant heterotrophic species in the inoculating sludge were preserved throughout the process in our previous research (Zhang et al.,2011).It is well known that AOB are chemoau-totrophic and slow-growing;accordingly,numerous AOBw a t e r r e s e a r c h x x x (2011)1e 106populations that cannot become big and dense enough to settle fast were washed out from the system.As a result,the variation in AOB was remarkable in the period of sludge inoculation,and the diversity index of population decreased rapidly.After day 45,AOB communities’structure became stable due to the improvement of sludge settleability and the retention of more biomass.These results suggest that the short settling time (selection pressure)apparently stressed the biomass,leading to a violent dynamic of AOB communities.Further,these results suggest that certain populations may have been responsible for the operational success of the GSBR and were able to persist despite the large fluctuations in pop-ulation similarity.This bacterial population instability,coupled with a generally acceptable bioreactor performance,is congruent with the results obtained from a membrane biore-actor (MBR)for graywater treatment (Stamper et al.,2003).Nitrosomonas e like and Nitrosospira e like populations are the dominant AOB populations in wastewater treatment systems (Kowalchuk and Stephen,2001).A few previous studies revealed that the predominant populations in AOB communities are different in various wastewater treatment processes (Tawan et al.,2005;Thomas et al.,2010).Some researchers found that the community was dominated by AOB from the genus Nitrosospira in MBRs (Zhang et al.,2010),whereas Nitrosomonas sp.is the predominant population in biofilter sludge (Yin and Xu,2009).In the currentstudy,Fig.5e DGGE profile of the AOB communities in different size of granules (lane labels along the top show the range of particle diameter (d,mm)).Values along the bottom indicate the Shannon diversity index (H ).Bands labeled with the numbers were consistent with the bands in Fig.3.w a t e r r e s e a r c h x x x (2011)1e 107sequence analysis revealed that selection pressure evidently effect on the survival of Nitrosospira in granular sludge.Almost all of Nitrosospira were washed out initially and had no chance to evolve with the environmental changes.However,some members of Nitrosomonas sp.have been shown to produce more amounts of EPS than Nitrosospira ,especially under limited ammonia conditions (Stehr et al.,1995);and this feature has also been observed for other members of the same lineage.Accordingly,these EPS are helpful to communicate cells with each other and granulate sludge (Adav et al.,2008).Therefore,most of Nitrosomonas could adapt to this challenge (to become big and dense enough to settle fast)and were retained in the reactor.At the end of reactor operation (day 180),granules with different particle size were sieved.The effects of variation in granules size on the composition of the AOBcommunitiesFig.6e Micrographs of FISH performed on three size classes of granule sections.DAPI stain micrographs (A,D,G);AOB appear as green fluorescence (B,E,H),and NOB appear as red fluorescence (C,F,I).Bar [100m m in (A)e (C)and (G)e (I).d,particle diameter.(For interpretation of the references to colour in this figure legend,the reader is referred to the web version of this article.)w a t e r r e s e a r c h x x x (2011)1e 108were investigated.As shown in Fig.5,AOB communities structures in different size of granules were varied.Although several predominant bands(bands2,5,11)were present in all samples,only bands3and6appeared in the granules with diameters larger than0.6mm.Additionally,bands7and10 were intense in the granules larger than0.45mm.According to Table2,it can be clearly indicated that Nitrosospira could be retained merely in the granules larger than0.6mm.Therefore, Nitrosospira was not present at a high level in Fig.3due to the lower proportion of larger granules(d>0.6mm)in TSS along with reactor operation.DGGE analysis also revealed that larger granules had a greater microbial diversity than smaller ones. This result also demonstrates that more organisms can survive in larger granules as a result of more space,which can provide the suitable environment for the growth of microbes(Fig.6).4.3.Effect of variance in particle size on the distribution of AOB and NOB in granulesAlthough an influence of granule size has been observed in experiments and simulations for simultaneous N-and P-removal(de Kreuk et al.,2007),the effect of granule size on the distribution of different biomass species need be revealed further with the assistance of visible experimental results, especially in the same granular sludge reactors.Related studies on the diversity of bacterial communities in granular sludge often focus on the distribution of important functional bacteria populations in single-size granules(Matsumoto et al., 2010).In the present study,different size granules were sieved,and the distribution patterns of AOB and NOB were explored.In the nitrification processes considered,AOB and NOB compete for space and oxygen in the granules(Volcke et al.,2010).Since ammonium oxidizers have a higheroxygen affinity(K AOBO2<K NOBO2)and accumulate more rapidly inthe reactor than nitrite oxidizers(Volcke et al.,2010),NOB are located just below the layer of AOB,where still some oxygen is present and allows ready access to the nitrite produced.In smaller granules,the location boundaries of the both biomass species were distinct due to the limited existence space provided by granules for both microorganism’s growth.AOB exist outside of the granules where oxygen and ammonia are present.Medium granules can provide broader space for microbe multiplying;accordingly,AOB spread out in the whole granules.This result also confirms that oxygen could penetrate deep into the granule’s core without restriction when particle diameter is less than0.6mm.Some mathematic model also supposed that NOBs are favored to grow in smaller granules because of the higher fractional aerobic volume (Volcke et al.,2010).As shown in the results of the batch experiments(Zhang et al.,2011),nitrite accumulation temporarily occurred,accompanied by the more large gran-ules(d>0.9mm)forming.This phenomenon can be attrib-uted to the increased ammonium surface load associated with larger granules and smaller aerobic volume fraction,resulting in outcompetes of NOB.It also suggests that the core areas of large granules(d>0.9mm)could provide anoxic environment for the growth of anaerobic denitrificans(such as Tb.deni-trificans or Tb.thioparus in Fig.S7,Supporting information).As shown in Fig.2and Fig.S3,the removal efficiency of total nitrogen increased with formation of larger granules.5.ConclusionsThe variation in AOB communities’structure was remarkable during sludge inoculation,and the diversity index of pop-ulation decreased rapidly.Most of Nitrosomonas in the inocu-lating sludge were retained because of their capability to rapidly adapt to the settling e washing out action.DGGE anal-ysis also revealed that larger granules had greater AOB diversity than that of smaller ones.Oxygen penetration was not restricted in the granules of less than0.6mm particle diameter.However,the larger granules(d>0.9mm)can result in the smaller aerobic volume fraction and inhibition of NOB growth.Henceforth,further studies on controlling and opti-mizing distribution of granule size could be beneficial to the nitrogen removal and expansive application of granular sludge technology.AcknowledgmentsThis work was supported by grants from the National Natural Science Foundation of China(No.51108456,50908227)and the National High Technology Research and Development Program of China(No.2009AA06Z312).Appendix.Supplementary dataSupplementary data associated with this article can be found in online version at doi:10.1016/j.watres.2011.09.026.r e f e r e n c e sAdav,S.S.,Lee, D.J.,Show,K.Y.,2008.Aerobic granular sludge:recent advances.Biotechnology Advances26,411e423.APHA-AWWA-WEF,2005.Standard Methods for the Examination of Water and Wastewater,first ed.American Public Health Association/American Water Works Association/WaterEnvironment Federation,Washington,DC.de Bruin,L.M.,de Kreuk,M.,van der Roest,H.F.,Uijterlinde,C., van Loosdrecht,M.C.M.,2004.Aerobic granular sludgetechnology:an alternative to activated sludge?Water Science and Technology49,1e7.de Kreuk,M.,Heijnen,J.J.,van Loosdrecht,M.C.M.,2005.Simultaneous COD,nitrogen,and phosphate removal byaerobic granular sludge.Biotechnology and Bioengineering90, 761e769.de Kreuk,M.,Picioreanu,C.,Hosseini,M.,Xavier,J.B.,van Loosdrecht,M.C.M.,2007.Kinetic model of a granular sludge SBR:influences on nutrient removal.Biotechnology andBioengineering97,801e815.Downing,L.S.,Nerenberg,R.,2008.Total nitrogen removal ina hybrid,membrane-aerated activated sludge process.WaterResearch42,3697e3708.Erguder,T.H.,Boon,N.,Vlaeminck,S.E.,Verstraete,W.,2008.Partial nitrification achieved by pulse sulfide doses ina sequential batch reactor.Environmental Science 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外文文献翻译原文Analysis of Con tin uous Prestressed Concrete BeamsChris BurgoyneMarch 26, 20051、IntroductionThis conference is devoted to the development of structural analysis rather than the strength of materials, but the effective use of prestressed concrete relies on an appropriate combination of structural analysis techniques with knowledge of the material behaviour. Design of prestressed concrete structures is usually left to specialists; the unwary will either make mistakes or spend inordinate time trying to extract a solution from the various equations.There are a number of fundamental differences between the behaviour of prestressed concrete and that of other materials. Structures are not unstressed when unloaded; the design space of feasible solutions is totally bounded；in hyperstatic structures, various states of self-stress can be induced by altering the cable profile, and all of these factors get influenced by creep and thermal effects. How were these problems recognised and how have they been tackled?Ever since the development of reinforced concrete by Hennebique at the end of the 19th century (Cusack 1984), it was recognised that steel and concrete could be more effectively combined if the steel was pretensioned, putting the concrete into compression. Cracking could be reduced, if not prevented altogether, which would increase stiffness and improve durability. Early attempts all failed because the initial prestress soon vanished, leaving the structure to be- have as though it was reinforced; good descriptions of these attempts are given by Leonhardt (1964) and Abeles (1964).It was Freyssineti’s observations of the sagging of the shallow arches on three bridges that he had just completed in 1927 over the River Allier near Vichy which led directly to prestressed concrete (Freyssinet 1956). Only the bridge at Boutiron survived WWII (Fig 1). Hitherto, it had been assumed that concrete had a Young’s modulus which remained fixed, but he recognised that the de- ferred strains due to creep explained why the prestress had been lost in the early trials. Freyssinet (Fig. 2) also correctly reasoned that high tensile steel had to be used, so that some prestress would remain after the creep had occurred, and alsothat high quality concrete should be used, since this minimised the total amount of creep. The history of Freyssineti’s early prestressed concrete work is written elsewhereFigure1:Boutiron Bridge,Vic h yFigure 2: Eugen FreyssinetAt about the same time work was underway on creep at the BRE laboratory in England ((Glanville 1930) and (1933)). It is debatable which man should be given credit for the discovery of creep but Freyssinet clearly gets the credit for successfully using the knowledge to prestress concrete.There are still problems associated with understanding how prestressed concrete works, partly because there is more than one way of thinking about it. These different philosophies are to some extent contradictory, and certainly confusing to the young engineer. It is also reflected, to a certain extent, in the various codes of practice.Permissible stress design philosophy sees prestressed concrete as a way of avoiding cracking by eliminating tensile stresses; the objective is for sufficient compression to remain after creep losses. Untensionedreinforcement, which attracts prestress due to creep, is anathema. This philosophy derives directly from Freyssinet’s logic and is primarily a working stress concept.Ultimate strength philosophy sees prestressing as a way of utilising high tensile steel as reinforcement. High strength steels have high elastic strain capacity, which could not be utilised when used as reinforcement; if the steel is pretensioned, much of that strain capacity is taken out before bonding the steel to the concrete. Structures designed this way are normally designed to be in compression everywhere under permanent loads, but allowed to crack under high live load. The idea derives directly from the work of Dischinger (1936) and his work on the bridge at Aue in 1939 (Schonberg and Fichter 1939), as well as that of Finsterwalder (1939). It is primarily an ultimate load concept. The idea of partial prestressing derives from these ideas.The Load-Balancing philosophy, introduced by T.Y. Lin, uses prestressing to counter the effect of the permanent loads (Lin 1963). The sag of the cables causes an upward force on the beam, which counteracts the load on the beam. Clearly, only one load can be balanced, but if this is taken as the total dead weight, then under that load the beam will perceive only the net axial prestress and will have no tendency to creep up or down.These three philosophies all have their champions, and heated debates take place between them as to which is the most fundamental.2、Section designFrom the outset it was recognised that prestressed concrete has to be checked at both the working load and the ultimate load. For steel structures, and those made from reinforced concrete, there is a fairly direct relationship between the load capacity under an allowable stress design, and that at the ultimate load under an ultimate strength design. Older codes were based on permissible stresses at the working load; new codes use moment capacities at the ultimate load. Different load factors are used in the two codes, but a structure which passes one code is likely to be acceptable under the other.For prestressed concrete, those ideas do not hold, since the structure is highly stressed, even when unloaded. A small increase of load can cause some stress limits to be breached, while a large increase in load might be needed to cross other limits. The designer has considerable freedom to vary both the working load and ultimate load capacities independently; both need to be checked.A designer normally has to check the tensile and compressive stresses, in both the top and bottom fibre of the section, for every load case. The critical sections are normally, but not always, the mid-span and the sections over piers but other sections may become critical ，when the cable profile has to be determined.The stresses at any position are made up of three components, one of which normally has a different sign from the other two; consistency of sign convention is essential.If P is the prestressing force and e its eccentricity, A and Z are the area of the cross-section and its elastic section modulus, while M is the applied moment, then where ft and fc are the permissible stresses in tension and compression.c e t f ZM Z P A P f ≤-+≤Thus, for any combination of P and M , the designer already has four in- equalities to deal with.The prestressing force differs over time, due to creep losses, and a designer isusually faced with at least three combinations of prestressing force and moment;• the applied moment at the time the prestress is first applied, before creep losses occur,• the maximum applied moment after creep losses, and• the minimum applied moment after creep losses.Figure 4: Gustave MagnelOther combinations may be needed in more complex cases. There are at least twelve inequalities that have to be satisfied at any cross-section, but since an I-section can be defined by six variables, and two are needed to define the prestress, the problem is over-specified and it is not immediately obvious which conditions are superfluous. In the hands of inexperienced engineers, the design process can be very long-winded. However, it is possible to separate out the design of the cross-section from the design of the prestress. By considering pairs of stress limits on the same fibre, but for different load cases, the effects of the prestress can be eliminated, leaving expressions of the form:rangestress e Perm issibl Range Mom entZ These inequalities, which can be evaluated exhaustively with little difficulty, allow the minimum size of the cross-section to be determined.Once a suitable cross-section has been found, the prestress can be designed using a construction due to Magnel (Fig.4). The stress limits can all be rearranged into the form:()M fZ PA Z e ++-≤1 By plotting these on a diagram of eccentricity versus the reciprocal of the prestressing force, a series of bound lines will be formed. Provided the inequalities (2) are satisfied, these bound lines will always leave a zone showing all feasible combinations of P and e. The most economical design, using the minimum prestress, usually lies on the right hand side of the diagram, where the design is limited by the permissible tensile stresses.Plotting the eccentricity on the vertical axis allows direct comparison with the crosssection, as shown in Fig. 5. Inequalities (3) make no reference to the physical dimensions of the structure, but these practical cover limits can be shown as wellA good designer knows how changes to the design and the loadings alter the Magnel diagram. Changing both the maximum andminimum bending moments, but keeping the range the same, raises and lowers the feasible region. If the moments become more sagging the feasible region gets lower in the beam.In general, as spans increase, the dead load moments increase in proportion to the live load. A stage will be reached where the economic point (A on Fig.5) moves outside the physical limits of the beam; Guyon (1951a) denoted the limiting condition as the critical span. Shorter spans will be governed by tensile stresses in the two extreme fibres, while longer spans will be governed by the limiting eccentricity and tensile stresses in the bottom fibre. However, it does not take a large increase in moment ，at which point compressive stresses will govern in the bottom fibre under maximum moment.Only when much longer spans are required, and the feasible region moves as far down as possible, does the structure become governed by compressive stresses in both fibres.3、Continuous beamsThe design of statically determinate beams is relatively straightforward; the engineer can work on the basis of the design of individual cross-sections, as outlined above. A number of complications arise when the structure is indeterminate which means that the designer has to consider, not only a critical section,but also the behaviour of the beam as a whole. These are due to the interaction of a number of factors, such as Creep, Temperature effects and Construction Sequence effects. It is the development of these ideas whichforms the core of this paper. The problems of continuity were addressed at a conference in London (Andrew and Witt 1951). The basic principles, and nomenclature, were already in use, but to modern eyes concentration on hand analysis techniques was unusual, and one of the principle concerns seems to have been the difficulty of estimating losses of prestressing force.3.1 Secondary MomentsA prestressing cable in a beam causes the structure to deflect. Unlike the statically determinate beam, where this motion is unrestrained, the movement causes a redistribution of the support reactions which in turn induces additional moments. These are often termed Secondary Moments, but they are not always small, or Parasitic Moments, but they are not always bad.Freyssinet’s bridge across the Marne at Luzancy, started in 1941 but not completed until 1946, is often thought of as a simply supported beam, but it was actually built as a two-hinged arch (Harris 1986), with support reactions adjusted by means of flat jacks and wedges which were later grouted-in (Fig.6). The same principles were applied in the later and larger beams built over the same river.Magnel built the first indeterminate beam bridge at Sclayn, in Belgium (Fig.7) in 1946. The cables are virtually straight, but he adjusted the deck profile so that the cables were close to the soffit near mid-span. Even with straight cables the sagging secondary momentsare large; about 50% of the hogging moment at the central support caused by dead and live load.The secondary moments cannot be found until the profile is known but the cablecannot be designed until the secondary moments are known. Guyon (1951b) introduced the concept of the concordant profile, which is a profile that causes no secondary moments; es and ep thus coincide. Any line of thrust is itself a concordant profile.The designer is then faced with a slightly simpler problem; a cable profile has to be chosen which not only satisfies the eccentricity limits (3) but is also concordant. That in itself is not a trivial operation, but is helped by the fact that the bending moment diagram that results from any load applied to a beam will itself be a concordant profile for a cable of constant force. Such loads are termed notional loads to distinguish them from the real loads on the structure. Superposition can be used to progressively build up a set of notional loads whose bending moment diagram gives the desired concordant profile.3.2 Temperature effectsTemperature variations apply to all structures but the effect on prestressed concrete beams can be more pronounced than in other structures. The temperature profile through the depth of a beam (Emerson 1973) can be split into three components for the purposes of calculation (Hambly 1991). The first causes a longitudinal expansion, which is normally released by the articulation of the structure; the second causes curvature which leads to deflection in all beams and reactant moments in continuous beams, while the third causes a set of self-equilibrating set of stresses across the cross-section.The reactant moments can be calculated and allowed-for, but it is the self- equilibrating stresses that cause the main problems for prestressed concrete beams. These beams normally have high thermal mass which means that daily temperature variations do not penetrate to the core of the structure. The result is a very non-uniform temperature distribution across the depth which in turn leads to significant self-equilibrating stresses. If the core of the structure is warm, while the surface is cool, such as at night, then quite large tensile stresses can be developed on the top and bottom surfaces. However, they only penetrate a very short distance into the concrete and the potential crack width is very small. It can be very expensive to overcome the tensile stress by changing the section or the prestress。