外文翻译1

译文（一）THE ACCOUNTING REVIEWV ol. 83, No. 3 2008pp. 823–853市场参与者的杜邦分析的使用马克•t•Soliman华盛顿大学文摘:杜邦分析,一种常见的财务报表分析，依靠于净营业资产收益率的两个乘法组件:利润率和资产周转率。

这两个会计比率衡量不同的构造。

因此,有不同的属性。

之前的研究已经发现,资产周转率的变化是未来收益的变化正相关。

本文全面探讨了杜邦组件和沿着三个维度有助于文学。

首先,本文有助于财务报表分析文献,发现在这个会计信息信号实际上是增量学习会计信号在先前的研究在预测未来收益。

其次,它有助于文学在股票市场上使用的会计信息通过检查眼前和未来的股本回报投资者应对这些组件。

最后,它增加了分析师的文献处理会计信息的再次测试直接和延迟反应的分析师通过同期预测修正以及未来预测错误。

一致的跨市场加入者的两组,结果表明是有用的信息就是明证杜邦组件和股票收益之间的联系以及维度分析师预测。

然而,我发现预测未来预测错误和异常返回信息处理表明似乎没有完成。

平均水平,分析表明杜邦组件代表增量和可行的操作特征信息的公司。

关键词:财务报表分析、杜邦分析、市场回报、分析师预估。

数据可用性:在这项研究中使用的数据是公开的来源显示的文本。

在本文中,我分析杜邦分析中包含的信息是否与股市回报相关和分析师预测。

之前的研究文档组件从杜邦分析,分解的净营业资产收益率为利润率和资产周转率,有解释力对未来盈利能力的变化。

本文增加了文献综合研究投资者和分析师反应杜邦组件三个维度。

首先,它复制先前记录的预测能力和检查是否健壮和增量其他预测已经考虑在文学的存在。

其次,它探讨了使用这些组件的股市投资者通过观察同生和未来收益。

在同时代的长窗协会和短时期限信息测试,结果显示积极联系杜邦组件和股本回报率。

但小未来异常返回交易策略显示的信息可能不完整的处理。

最后,检查当前预测修正由卖方分析师和未来的预测错误。

外文翻译一：Excerptwords to more and more complex phrases. Children learn to listen and to talk long before they learn to read and write. The same sequence should be followed in classroom teaching. Extra difficulty would be created if one would try to develop English reading and writing skills before children can speak the language. In order to be able to speak the language, students need to know some vocabulary first. In this paper I will focus on how to teach vocabulary that enables students to construct a rich vocabulary bank. Guiding methods are introduced and sample activities are provided.II. Main Part1. The Importance of Teaching Vocabulary1.1. Vocabulary Development in the Primary GradesThe findings of the “National Reading Panel” indicate that vocab ulary instruction does lead to gains in comprehension, but that methods must be appropriate to the age and ability of the reader. Using both indirect and direct teaching methods to build students’ oral and reading vocabularies should be a part of a balanced reading program. Indirect methods would include read-alouds, shared reading and writing experiences, and independent reading. Direct teaching of vocabulary should respond to the needs of the students and should actively engage them in the process(National Reading Panel, 2000).All word learning tasks are not equal in difficulty. A child may understand the concept behind a word, but not know the word itself. For example, the word cease represents a known concept to most children; however, a young child has probably not heard this word used for stop.Learning a new word that represents a known concept is not as difficult as learning a new word that represents a new concept. Teachers in the primary grades introduce many new concepts, and direct instruction is necessary to build up the understanding of these concepts and the vocabulary words that represent them.When teaching vocabulary words that represent known concepts, the emphasis should always be on the context in which the word appears. Discussing the meaning2of the word from the context of the reading selection together with supplying a definition of the word will help to build meaning for students. If students are to acquire this word as part of their vocabulary, then they must be given repeated exposure of the word in a variety of contexts. They must also have opportunities to practise using the word in conversation and/or writing.By the time children enter second grade, they are likely to know between 2,000 and 5,000 vocabulary words. This amazing growth continues throughout the elementary years, as most children gain 3,000 - 4,000 new vocabulary words each year that they can read and understand ( Teaching Reading in the 21st Century, 2001). By encouraging independent reading and providing both indirect and direct instruction in vocabulary, students can be helped to develop the vocabulary knowledge they will need for effective comprehension.1.2. Educators View on Teaching Vocabulary"Teaching one word at a time out of context is the worst way of teaching vocabulary, with rapid forgetting almost guaranteed," asserts Frank Smith, author of "The Book of Learning and Forgetting" (1998), recently published by Teachers College Press. According to Smith, people assimilate new vocabulary words from context the first time they read them, "provided that the gist of the material being read is both interesting and comprehensible. Within five more encounters, the word and its conventional meaning are usually firmly established in the mind of the reader."Other educators who share this view add that when reading material isn't instantly interesting or comprehensible, it's the teacher's job to build context by activating students' prior knowledge of the topic. With regard to vocabulary, that means having students identify difficult words themselves and pool their knowledge to get the meaning. Ann Marie Longo, director of the Boys Town Reading Center, argues that teens can't use context effectively when their vocabularies are limited. Limited vocabulary is the most common problem among weak readers she's worked with. Longo begins with indirect instruction in words and their meanings and then provides high-interest opportunities to use the words. Vocabularyexpert Isabel Beck of the University of Pittsburgh embraces both approaches. For her, there are3four ways to learn vocabulary: wide reading, hearing unfamiliar words in speech, direct instruction in words and "gimmicks" to boost students' interest.Beck suggests teachers incorporate difficult words into their classroom routines and encourage students to look for the words in reading outside class. Longo agrees that students need to put new words to use in writing and conversation as well as reading. "For vocabulary instruction to increase comprehension," says Longo, "you have to see those words over and over again" ( When Adolescents Can´t Read: Methods and Materials that Work, 1999).1.3. Memory and Storage SystemsUnderstanding how our memory works might help us create more effective ways to teach vocabulary. Research in the area, cited by Gairns and Redman (1986) offers us some insights into this process. It seems that learning new items involve storing them first in our short-term memory, and afterwards in long-term memory. We do not control this process consciously but there seem to be some important clues to consider. First, retention in short-term memory is not effective if the number of chunks of information exceeds seven. Therefore, this suggests that in a given class we should not aim at teaching more than this number. However, our long-term memory can hold any amount of information.Research also suggests that our “mental lexicon” is highly organised and efficient, and that semantic related items are stored together. Word frequency is another factor that affects storage, as the most frequently used items are easier to retrieve. We can use this information to attempt to facilitate the learning process, by grouping items of vocabulary in semantic fields, such as topics (e.g. types of fruit). Oxford (1990) suggests memory strategies to aid learning, and these can be divided into creating mental linkages (grouping, associating, placing new words into a context), applying images and sounds (using imagery, semantic mapping, using keywords and representing sounds in memory), reviewing in a structured way and employing action (physical response or sensation, using mechanical techniques). The techniques just mentioned can be used to greater advantage if we can diagnose learning style preferences (visual, aural, kinesthetic, tactile) and make students aware of different memory strategies.4Meaningful tasks, however, seem to offer the best answer to vocabulary learning, as they rely on students’ experiences and reality to facilitate learning. More meaningful tasks also require learners to analyse and process language more deeply, which should help them retain information in long-term memory. Forgetting seems to be an inevitable process, unless learners regularly use items they have learnt. Therefore, recycling is vital, and ideally it should happen one or two days after the initial input. After that, weekly or monthly tests can check on previously taught items. The way students store the items learned can also contribute to their success or failure in retrieving them when needed. Most learners simply list the items learnt in chronological order, indicating meaning with translation. This system is far from helpful, as items arede-contextualised, encouraging students to over generalise their usage. It does not allow for additions and refinements nor does it indicate pronunciation. Teachers can encourage learners to use other methods, using topics and categories to organise a notebook, binder or index cards. Meaning should be stored using English as much as possible. Diagrams and word trees can also be used within this topic/categories organisation. The class as a whole can keep a vocabulary box with cards, which can be used for revision/recycling regularly.1.4. Why Vocabulary is ImportantTeachers may wonder why it is important to teach vocabulary. Well, there is a very clear answer to that question, namely that vocabulary is critical to reading success for three reasons, which I will explain now briefly. First of all, comprehension improves when you know what the words mean. Since comprehension is the ultimate goal of reading, you cannot overestimate the importance of vocabulary development. Secondly, words are the currency of communication. A robust vocabulary improves all areas of communication which are listening, speaking, reading and writing. Last but no least, when children and adolescents improve their vocabulary, their academic and social confidence and competence improve, too.In turn, a deficit in vocabulary knowledge causes comprehension problems, and comprehension problems prevent people from improving their vocabulary knowledge on their own. Intensive vocabulary instruction can be effective in turning this situation around. What is required, though, is a clear and deliberate focus on facilitating students’ creation of meaning ful contexts for the word meanings they are learning,5and a frequent and consistent emphasis on helping them make connections to what they already know.1.5. Levels of Word Knowledge“Word knowledge” refers to how well you know the meaning of a word. Research shows that there are three kinds of word knowledge. Firstly, there is a lack of word knowledge where the meaning is completely unfamiliar. Secondly, there is acquired word knowledge where the basic meaning is recognized after some thought. And last, there is established word knowledge where the meaning is easily, rapidly and automatically recognized (Beck, McKeown, and Omanson, 1987). Words from the third category are already established in the personal vocabulary bank and are the words you would use in conversation and writing. Though it’s enough for students to have a surface understanding of some words in a selection, for most words students must have this same established level of knowledge if they are to understand what they are reading (Nagy, Herman, and Anderson, 1985).2. Teaching Vocabulary2.1. Which Words Should be TaughtWhen making instructional decisions as to which words to teach, it is helpful to have a framework for decision-making in this area. Knowing what words to teach is the first step in providing effective vocabulary practice. Graves and Prenn, for instance, classify the words that should be devided into three types, each requiring a higher investment of teacher and learner time for instruction. With words that are already in the student's oral vocabulary, the students need only to identify the written symbol for such a word. When the word is one for which the student has acquired no concept and it appears frequently in the context, the teacher must take time to develop the concept through instruction. When the word is in the student's listening vocabulary, it may be taught though writing experiences and activities. Focus should be on helping students become independent learners; they should be encouraged to become actively involved in selecting words.6I will shortly mention a practical guide that helps teachers to remember the types of words that they should teach explicitly. First of all, there are Type A Words.These words belong to academic language and thecontent areas.Academic language describes the language of schooling,words used across disciplines like genre and glossary. Content area words are specific to the discipline, words like organization in social studies and organism in science. Then there are Type B Words which arethe basics.There are hundreds of high-frequency words. The basics make up a large percentage of students´ reading and writing. Students must be able to read words like the, is, and, are, been and because.The so-called Type C Words are connectors and act as signal words. There may be some overlap with the basic words. Students need to understand the signals for cause and effect relationships, sequence and other important indicators of how text is organized. In Type D Words the D standsfor difficult- words with multiple meanings are a challenge for all students and may be especially so for learners of the English language.When considering words with multiple meanings teachers should also pay attention to the consonant-vowel-consonant words children encounter when first learning to read - for example words like jam and ham.These words have accessible meanings if you think of something you may eat with eggs in the morning (ham) or of the sweet, sticky stuff on toast (jam). But jam also describes a music playing session. So learning to decode should not be meaning-free, but should provide a good opportunity for teaching the meanings of words including multiple ones. This kind of experience with words improves comprehension.At last there are also Type X Words which are the extras. These are the words that will not be encountered frequently but in a certain story or context they are important for decoding meaning. A good example of this type of word is spindle in “Sleeping Beauty.” It is important to the fairy tale, but it is not a very high-utility word. I just tell kids what words like this mean without any special teaching.2.1.1. Basic Functional VocabularyIn order to understand, speak, read and write a language, the students must acquire the basic functional vocabulary. New words are carefully selected, gradually introduced, and graded to make language learning smooth and easy. The following77 of 27 pages - scroll topInformation on this eBookTitleThe Teaching of Vocabulary in the Primary School Foreign Language ClassroomAuthorDaniela PohlYear2003Pages27Archive No.V34883ISBN (eBook)978-3-638-34971-0ISBN (Book)978-3-640-44099-3DOI10.3239/9783638349710File size224 KBLanguageEnglishTagsTeachingVocabularyPrimarySchoolForeignLanguageClassroom翻译部分：国外小学词汇教学（The Teaching of Vocabulary in the Primary School Foreign Language Classroom）摘要：很多词语都变得越来越复杂，拥有很多的词组。

Parsimony versus precision: framing, agenda setting, and priming
The three models we focus on in this issue—framing, agenda setting, and priming—have received significant scholarly attention since they were introduced. Agenda setting refers to the idea that there is a strong correlation between the emphasis that mass media place on certain issues (e.g., based on relative placement or amount of coverage) and the importance attributed to these issues by mass audiences (McCombs & Shaw, 1972). As defined in the political communication literature, Priming refers to‘changes in the standards that people use to make political evaluations’(Iyengar & Kinder, 1987, p. 63). Priming occurs when news content suggests to news audiences that they ought to use specific issues as benchmarks for evaluating the performance of leaders and governments. It is often understood as an extension of agenda setting.

因为学校对毕业论文中的外文翻译并无规定，为统一起见,特做以下要求：1、每篇字数为1500字左右，共两篇；2、每篇由两部分组成:译文+原文.3 附件中是一篇范本，具体字号、字体已标注。

外文翻译（包含原文)(宋体四号加粗）外文翻译一（宋体四号加粗）作者：(宋体小四号加粗）Kim Mee Hyun Director, Policy Research & Development Team，Korean Film Council（小四号）出处：(宋体小四号加粗)Korean Cinema from Origins to Renaissance(P358～P340) 韩国电影的发展及前景（标题：宋体四号加粗）1996～现在数量上的增长(正文:宋体小四）在过去的十年间，韩国电影经历了难以置信的增长。

上个世纪60年代，韩国电影迅速崛起，然而很快便陷入停滞状态,直到90年代以后，韩国电影又重新进入繁盛时期。

在这个时期，韩国电影在数量上并没有大幅的增长，但多部电影的观影人数达到了上千万人次。

1996年，韩国本土电影的市场占有量只有23.1%。

但是到了1998年，市场占有量增长到35。

8%，到2001年更是达到了50%。

虽然从1996年开始，韩国电影一直处在不断上升的过程中，但是直到1999年姜帝圭导演的《生死谍变》的成功才诞生了韩国电影的又一个高峰。

虽然《生死谍变》创造了韩国电影史上的最高电影票房纪录，但是1999年以后最高票房纪录几乎每年都会被刷新。

当人们都在津津乐道所谓的“韩国大片”时，2000年朴赞郁导演的《共同警备区JSA》和2001年郭暻泽导演的《朋友》均成功刷新了韩国电影最高票房纪录.2003年康佑硕导演的《实尾岛》和2004年姜帝圭导演的又一部力作《太极旗飘扬》开创了观影人数上千万人次的时代。

姜帝圭和康佑硕导演在韩国电影票房史上扮演了十分重要的角色。

从1993年的《特警冤家》到2003年的《实尾岛》，康佑硕导演了多部成功的电影。

2.3.2 公制,标准尺寸图梯形齿廓标准同步皮带由聚氨酯与钢或芳纶抗拉元件制成。

符号T代表梯形齿廓标准带。

WHM公司与国内GmbH公司和德国的Hanover公司合作，在1995年前后联合开发了这种同步带。

MULCO团体在德国以Synchroflex为品牌名发行这种同步带，之后又在欧洲发行。

在1997年这种带被标准化了，其标准为DIN772。

这些带遍布世界各地，并可作为成型的环形带，无尽的连接带和开口带使用。

具有梯形齿廓和公制标准尺寸，AT同步带是T型同步带的一个发展。

它们由由聚氨酯与钢或芳纶抗拉元件制成。

与T型同步带先比，AT型同步带有更宽的齿形截面和更强的抗拉构件。

AT型同步带一个特殊的特点是带齿齿隙紧靠带轮槽底座。

德国的MULCO和Hanover公司开发了这种类型的同步带，并在1980年左右以Synchroflex为品牌发行了这种带。

这些带遍布世界各地，并可作为成型的环形带，无尽的连接带和开口带使用。

这些带ISO 13050 标准用符号H表示，也被称为HTD同步带。

HTD代表大扭矩驱动。

这种同步带是由氯丁橡胶与玻璃纤维抗拉元件和聚酰胺纤维织物制成，并由在1973年引领美国市场的Gates公司开发。

曲齿的几何形状是圆形，较大的齿高显然增加了齿承载能力和抗牙跳能力。

这种带在世界各地都可以看到，许多制造商都参与它的生产。

它们也用聚氨酯，任选与钢丝帘线或芳纶抗拉元件制造。

用户可以从无尽的成型带，开口带和连续挤压环形带中选择使用。

这些带ISO 13050 标准用符号R表示，也被称为RPP同步带。

RPP代表橡胶抛物线。

1985年意大利的公司开发了这种双抛物线齿廓的同步带，他们是由氯丁橡胶与玻璃纤维抗拉元件和聚酰胺纤维织物制成。

这种类型的同步带主要发行在欧洲南部，许多制造商都参与它们的生产。

它们也用聚氨酯，任选钢丝帘线或芳纶抗拉元件制造。

用户可以从无尽的成型带，开口带和连续挤压环形带中选择使用。

这些带ISO 13050 标准用符号S表示，也被称为STD同步带。

外文翻译原文“Translation”Translation is the process of converting written text or speech from one language to another. It is a complex task that requires not only fluent proficiency in both languages, but also a deep understanding of the cultural nuances and linguistic intricacies of each language.Translation has been practiced for centuries and has played a crucial role in facilitating communication and fostering cultural exchange between different societies. It allows people who speak different languages to communicate and interact with each other, breaking down barriers and expanding possibilities.There are various types of translation, including literary translation, technical translation, legal translation, and medical translation, among others. Each type requires specific knowledge and skills to accurately convey the meaning and intent of the original text.In addition to linguistic accuracy, a good translator should also strive to capture the style, tone, and nuances of the original text. This involves understanding the cultural and historical context of the text, as well as the intended audience. Often, a translator needs to make decisions about how to adapt the text to the target language while still preserving its essence.Translation can be a challenging and time-consuming process, especially when dealing with complex or specialized subjects. Translators often need to conduct thorough research to ensure accuracy and maintain the integrity of the original text.With the advancement of technology, machine translation has become increasingly popular in recent years. However, while machine translation can provide quick and convenient translations, it often lacks the accuracy and nuance that human translators can offer. Human translators are able to understand the subtleties of language and idiomatic expressions that are often lost in machine translations. Therefore, it is important to rely on human translators, especially for important or sensitive documents.In conclusion, translation is a vital tool in facilitating communication and promoting cultural understanding. It requires not only language proficiency but also a deep understanding of cultural nuances. While machine translation can offer convenience, human translators are essential for accurate and nuanced translations.。

(完整版)PLC中英文资料外文翻译(1)编辑整理：尊敬的读者朋友们：这里是精品文档编辑中心，本文档内容是由我和我的同事精心编辑整理后发布的，发布之前我们对文中内容进行仔细校对，但是难免会有疏漏的地方，但是任然希望（(完整版)PLC中英文资料外文翻译(1)）的内容能够给您的工作和学习带来便利。

同时也真诚的希望收到您的建议和反馈，这将是我们进步的源泉，前进的动力。

本文可编辑可修改，如果觉得对您有帮助请收藏以便随时查阅，最后祝您生活愉快业绩进步，以下为(完整版)PLC中英文资料外文翻译(1)的全部内容。

（完整版）PLC中英文资料外文翻译(1)编辑整理：张嬗雒老师尊敬的读者朋友们：这里是精品文档编辑中心，本文档内容是由我和我的同事精心编辑整理后发布到文库，发布之前我们对文中内容进行仔细校对,但是难免会有疏漏的地方，但是我们任然希望 (完整版)PLC中英文资料外文翻译（1）这篇文档能够给您的工作和学习带来便利。

同时我们也真诚的希望收到您的建议和反馈到下面的留言区，这将是我们进步的源泉，前进的动力。

本文可编辑可修改，如果觉得对您有帮助请下载收藏以便随时查阅，最后祝您生活愉快业绩进步，以下为〈(完整版)PLC中英文资料外文翻译(1)> 这篇文档的全部内容。

可编程控制器技术讨论与未来发展摘自《可编程控制器技术讨论与未来发展》数字媒体系 08165110 多衡随着时代的发展,当今的技术也日趋完善、竞争愈演愈烈；单靠人工的操作已不能满足于目前的制造业前景,也无法保证更高质量的要求和高新技术企业的形象。

人们在生产实践中看到，自动化给人们带来了极大的便利和产品质量上的保证,同时也减轻了人员的劳动强度,减少了人员上的编制.在许多复杂的生产过程中难以实现的目标控制、整体优化、最佳决策等，熟练的操作工、技术人员或专家、管理者却能够容易判断和操作,可以获得满意的效果。

人工智能的研究目标正是利用计算机来实现、模拟这些智能行为,通过人脑与计算机协调工作,以人机结合的模式，为解决十分复杂的问题寻找最佳的途径我们在各种场合看到了继电器连接的控制,那已经是时代的过去，如今的继电器只能作为低端的基层控制模块或者简单的设备中使用到；而PLC的出现也成为了划时代的主题，通过极其稳定的硬件穿插灵活的软件控制,使得自动化走向了新的高潮。

南京邮电大学毕业设计(论文)外文资料翻译学院(系)：经济与管理学院专业：学生姓名：班级学号：外文出处：Journal of Occupational Psychology,1977, Vol.50附件：1.外文资料翻译译文；2.外文原文附件：1.外文资料翻译译文重新评估工作满意度和工作生活质量——詹姆斯.C.泰勒有用的工作满意度的措施在评估工作的特点以及改善工作生活质量中是有问题的。

根据民意调查和组织调查显示，多年以来，虽然在高和稳定的工作满意度水平下，雇员的挫折感和异化迹象却一直在增加。

经过更密切的检查，这似是而非的调查导致的结论是：无论再严谨的工作满意度调查及测量，得到的只是修改工作和减少员工的挫折感方面的没必要的信息。

根据以往的经验以及对工作生活质量的研究表明，为了克服这个缺陷，在测量工作满意度的时候，雇员本身需要更多地参与测量。

工作满意度已经成为一个模糊不清的尴尬概念。

许多代表着工业人文主义利益的社会科学调查员都对工作满意度十分有兴趣，他们建议要去关注和改善人与职位的关系，提高工作满意度。

从20世纪30年代开始，这种关注已经从制造业扩展到服务和文职部门。

然而，我们可以断言，大部分对工作满意度的研究都无法仅通过对工作及工作本身的研究。

历史上曾经有过对工作满意度的研究，这或许可以支持或者攻击现状，这种趋势还将继续下去。

尴尬的是，在对美国雇员的工作满意度的继续调查研究中，用极高的百分比来衡量他们工作的满意程度，而在同一时间内降低对工人的承诺，雇员所表达的通过增加缺勤率（特别是部分周缺勤），罢工（因其他原因除了工资）而拒绝谈判达成的合同以及破坏产品的比率显然变得更大。

雇员异化的这些问题已经提起公众的注意，但是如果公众关注继续增长，为什么雇员安静的绝望与工作越来越被看作是与压力之间的和解，这些事实和精心准备将使对工作满意度的严格调查成为必然。

前言本文的目的是在不减少抽样误差和防范反应的情况下，使用更精密的统计测试，在不同的模式下对满意度数据进行界定和衡量。

注：红色字体表示语句不明白的地方，请求学姐帮忙。

聚亚烷基二醇的化学结构和它们在含水环境中的好氧生物降解性之间的关系简要：使用一组聚合流体，其中包括聚乙二醇、聚丙二烯（PPG）、不同EO/PO 比率的环氧乙烷（EO）的无规共聚物和环氧丙烷（PO），对聚亚烷基醇（PAG）的化学结构和它们的生物降解性之间的关系进行研究以及用PAG的醚和酰基部分封端。

被测试的PAG中有一个均分子量范围在350-3600Da，它们的差异是由其聚合物主链的直链（二醇型）或支链（三元醇型）分子。

PAG的最终生物降解能力是根据ISO14593（CO2顶空试验）用非预曝光（如在OECD310试验）和预曝光（改编）接种物来确定。

带有PPG结构和二元醇或三元醇的EO/PO共聚物，均分子量不超过1000沓的PAG，被认为是易于生物降解的。

他们的最终生物降解可超过60％的限制（根据OECD310测试标准）。

具有共聚结构并且MW值在1000-3600之间的PAG不易生物降解，但它们可以被看做是那些固有的最终降解物。

在PAG结构中EO含量的增长和末端羟基的酰化与羧酸基团有利地影响了他们的生物降解性。

含末端醚基团封端的PAG似乎是耐生物降解的。

关键词生物降解、聚亚烷基二醇、PAG、PPG、封顶PAG、ISO14593。

引言：术语中的聚亚烷基二醇-PAG，以及在相关文献中的PAG，例如，聚乙二醇，聚醚和聚（烯化氧）中使用的PAG术语都是带有环氧化物结构烯化氧聚合得到的化合物。

PAG主要是通过使用乙烯和丙烯的氧化物合成的，不常使用丁二醇和更高的烯烃氧化物。

PAG类化合物（不同的分子量，性能和应用）最常用的包括氧化乙烯或丙烯均聚物氧化物以及乙烯和丙烯氧化物的无规或嵌段共聚物。

PAG的分子结构不仅取决于种类和亚烷基氧化物的比例，而且还取决于用于聚合反应的引发剂分子的类型（单-，二-或多官能分子具有2个以上活泼氢原子）。

引发剂影响PAG分子的末端羟基基团和聚合物链的类型，其可以是线性的（单醇及二醇型）或支链的（多元醇的数类型）。

一曲人性美的田园牧歌———《边城》之美摘要: 沈从文以乡下人的主体视角审视城乡对峙的现状, 热情讴歌了湘西人民的人性美, 描绘了一个瑰丽而温馨的边城世界, 展现出一个诗意的自然环境: 精致柔美而宁静, 远离都市的喧嚣与浮华。

从而提出了他的人与自然和谐共存, 本于自然, 回归自然的哲学。

关键词: 人性美; 田园牧歌; 桃源仙境《边城》是沈从文的代表作, 也是中国现代文学史上优秀的中篇小说之一, 被人们誉为中国现代文学牧歌传说中的顶峰一颗千古不磨的珠玉。

20世纪20年代初, “京派”文人作家群的首席小说家、“乡下人”，沈从文, 从湘西地区的灵山秀水中走出, 以其30年复杂的人生阅历为基础, 通过老船夫、翠翠等人物形象的描绘, 对人类生命与人性的释放形式及其原因进行了探究、认知与感慨, 热情讴歌了湘西人民的人性美。

可以说, 《边城》是沈从文理想人生的缩影, 是一首作家写给故乡的赞美诗, 是作者远离边城而作于都市的梦, 是一曲优美动人的湘西人性美的颂歌。

施蛰存说: “从文处于苗汉杂居的湘西, 他最熟悉的是这一地区的风土人情。

非但熟悉, 而且热爱”。

在沈从文童年记忆中, 存储着一幅理想世界中美丽湘西地域风俗画: 那里的男人豪爽仗义, 刚健顽强; 那里的女人纯朴善良, 热情厚道。

他们重承诺, 守信义, 敢爱敢恨, 对爱情忠贞不渝。

这些普通的山民村妇、痴男怨女和他们的动人故事与美好人性, 便成了沈从文永远的生命崇拜图腾。

由此, 沈从文怀着探究人生“生命的形式”, 抨击否定虚伪人性, 赞美宣示美好人性的初衷, 创作了《边城》。

“有一小溪, 溪边有座白色小塔, 塔下住了一户单独的人家。

这人家只一个老人, 一个女孩子, 一只黄狗。

小溪流下去, 绕山岨流, 约三里便汇入茶峒的大河。

人若过溪越小山走去, 则只一里路就到了茶峒城边。

溪流如弓, 山路如弦, 故远近有了小小差异。

小溪宽约二十丈, 河床为大片石头作成。

静静的水即或深到一篙不能落底, 却依然清澈透明, 河中游鱼来去皆可以计数。

文献出处 : Humble M . The study of ex press log i stics netw ork opt imizat ion [ J ] . Operations R esearch Perspect ives, 2016, 6 (3):106 -115 .原文The st udy of ex press log ist ics netw ork optim izationHumble MA bst ractEx press indust ry as an important part of m odern log ist ics indust ry to become one of the fast est g row ing indust ries in recent y ears. The rapid development of ex press indust ry lead to a lot of capit al inflow ex press delivery m arket, thus express companies, t here are many sizes for g rab market resources,the com petit ion bet w een ent erprises is becoming more and fiercer.Ex cessive com petit ion caused a lot of w ast e of resources, reduce the ut ilizat ion of resources, and increase the cost of log i stics.In order to solve t hese problems need to int eg ra te the expres s industry resources, increase the concent rat ion of indust ry level.A nd C ourier companies merg ers and reorg anization is the int eg ration betw een the express industry resources,ex press delivery indust ry compet it iveness effect ive w a y. Express log i stics net w ork in t he ex press indust ry i s reg arded as ex press the l ifeblood of ent erprises, of w hich the end of the service net w ork (hereinaft er referred to as end nodes), the dist ribution cent er,the urban reg ional hub ( hereinaft er referred to as the reg ional hub) and the num ber of spatial lay out direct ly det ermines the operation m ode of delivery a nd quality of operat ions. Therefore, under the merg er rest ruct uring ent erprises express log i stics net w ork optim ization int eg ration to ex press the development of the ent erprise aft er the m erg er and reorg anizat ion play s a decisive role.Key w ords:M erg ers and reorg a nization;Netw ork opt imizat ion int eg ra t ion; End node;Dist ribution center1 Int roductionLog is t ics net w ork t heory is the inevit able out come of the development of log ist ics manag ement research Gum constantly, is a st andardized, sy st emat ic and scientific research important w a y of m odern log ist ics, i t ex panded the log i stics netw ork operations research new tra in of t houg ht, provides a t heoretical basis for the log i st ics netw ork opt im izat ion. DJ B ow ers ( 2007 ) put forw ard the theory of supply chain log istics int eg ra tion,and based on log istics, w a rehouse locat ion,t ransport ation cost, invent ory cost, e t c , int eg ra t ing advanced the t heory of int eg rationa rchitect ure. M S R am m . ( 2009 ) int eg ra ted log i stics net w ork i s a c losed loop int eg rated forw ard/re verse log i stics net w ork,including production/re covery,m ix ed distribution,custom e rs, collect ing and processing cent er, etc., first used to det ermine the m ix ed integ er linear prog ram m ing model for log i stics netw ork int eg ration, and t hen in uncertain scenarios using the mix ed integ er l inear prog ram ming model, the model can avoid suboptimal result s caused by separat ion and continuous. M a ria B oiler mud ( 2013 ) in a nonlinear integ er model to solve the dy namic integ ra ted forw ard and reverse dist ribution netw ork desig n model double H st andards to minim ize t ransport cost s a nd tim e; Int eg ra t ed log i st ics netw ork facilit y locat ion problem to improve the efficiency of forw ard and reverse log istics,mainly i s the det erm ination of three ty pes of facilit ies, w arehouse ( log i stics), collection cent ers ( reverse log i stics) and mix ed facilities ( forw ard and reverse log ist ics).2Ex press log ist ics net w ork1 S ummary of log i st ics netw orkDonald j . B ow er and David i ts loss in the book of the process of log i st ics m anag ement, supply chain int eg rat ion point s out t hat the w hole log i stics netw ork desig n has a direct impact on the log i st ics efficiency, to provide cust omer service capabilit ies and cost mainly by num ber of log i stics facilities,the influence of the pract ical fact ors such as scale;Essential part of netw ork la y out desig n i s to det erm ine the num ber of every k ind of facilit ies,locat ion and job,et c.; In the constantly chang ing compet it ive environment,the ty pes of product s,cust omer dema nd chang es a t the mom ent,so perfecting the infrast ructure net w ork to adapt to the chang e of supply and demand i s very import ant.R onald h. B a l loon ( 2010 ) arg ues that the essence of the net w ork st ruct ure problem i s to det ermine from to the cust omer's net w ork st ructure,including the facilit y ty pe, num ber, locat ion and each facilit y betw een the determ inat ion of amount of product s and cust om ers; In his book "log istics manag ement", l ist s the data needed for log i stics netw ork int eg rat ion, and put forw ard the evaluation and the evaluat ion of ent erprise log istics net w ork in the g eneral audit criteria. L og i st ics net w ork has the follow ing charact eristics: log i stics net w ork has the charact eristics of hig h efficiency. The g oal of log i stics netw ork is the low est cost for a shorter t ime w ould be delivered g oods in g ood condition of t he demand s ide, the max imum com bination of log i stics and inform a tion flow,cash flow to achieve "zero invent ory, a short period of t ime,no interm i tt ent t ransmission" i s the ideal state.The openness of the log i s t ics i s net w ork. Openness i sthe foundat ion of log i stics nodes can be t hroug h the public netw ork, a ll nodes connect ed directly or indirectly. L og i stics netw ork openness enables each node and ot her nodes ex chang e information quickly,processing business. Pilot log i s t ics netw ork inform a t ion.W idespread use of mechanizat ion and aut omat ion equipment can g reatly improve the level of inform a tion of log i stics netw ork, but the collection,manag ement,analy sis and m ining equipm e nt in the process of log i stics informat ion i s more import ant.The informat ion in the log istics net w ork t hroug hout the log istics activit y a lw a y s , to the operat ion of log ist ics netw ork as a w hole have the funct ion of the g uidance and int eg ra tion.Log ist ics net w ork has the s ize advant ag e . S cale i s the important a ims of log i st ics net w ork. Dispersion formed in the fie ld of log i stics, log i stics netw ork nodes and the charact eristic of manag ement, w i l l hig hlig ht i ts scale advant ag e . Throug h la rg e-scale joint operation of log istics nodes can fully improve the effic iency of the w hole operat ion of the log i st ics net w ork, reduce the cost of the overall operation,reliance on a sing le node of log i stics netw ork is a l so s ig nificant ly reduced; C an't w ork normally even if t here i s a node, ot her nodes can quickly m ak e up for i t, resist risk abilit y.2 The charact erist ics of the ex press log ist ics netw orkEx press log i st ics netw ork m a inly includes t hree part s, main t ransport netw orks,and distribution net w orks, from end off. Every part of the netw ork composit ion and the exercise of the funct ions of each are not identical. B ackbone t ransport net w ork i s ma inly betw een reg ional hub and reg ional hub and dist ribut ion center of the net w ork, i t i s ma inly long dist ance transportation, mainly by car and a i r t ransport w a y. Distribut ion net w ork is mainly bet w een dist ribut ion center and end node netw ork, g oods dist ribut ion t hroug h the distribution cent ers, arrived a t the end of the subordinat e branches. From end off net w ork composed of cust omers and end node, i t i s the first l ink i s the final l ink of express delivery business, is a lso an im port ant part of the cust omer experience.The different met hods of delivery of g oods produced tw o ty pes of net w orks: shaft ty pe and the ent ire company g eneral form ula ex press log i stics netw ork. A m ong t hem, the major st ructure of the radiation i s the hub of part ition netw ork charact erist ics, in each partit ion can have one or more of the hub, the hub node can not only send and receive the g oods w i t hin the reg ion but a l so can connect ot her areas of the hub node, t ransit and sorting is a l so i ts funct ion. In the ax i s of t he ty pe express log i stics netw ork, transport of g oods need to transport to the hub node, t hroug h sortingt ransit hub node before handing out again. Fully connect ed netw ork i s any node is ex chang ed bet w een, should have the shipping l ine directly connect ed. The connect ed net w ork can realize g oods direct ty pe dist ribution bet w een any nodes on the net w ork,but t his w a y of dist ribut ion w i l l be an additional shipping cost. B ecause of the dispersed dist ribution and sm a l l feat ures express C ourier companies i s the main dist ribution object,so ax ia l radial express m ore t han log ist ics net w ork a l l over a long w i th the netw ork helps to improve log ist ics resources int eg ra t ion, log istics resource ut ilizat ion,to reduce log i st ics cost,shaft f ty pe ex press log i stics netw ork more in l ine w i th the act ual sit uation of delivery operat ion.3The com p osition of ex press log i s t ics netw ork3 .1 Delivery terminal net w orkDelivery a t the end of the node is the beg inning of the express log i stics netw ork point and end point,its main function i s to Posting and expresses m a i l delivery.End point s a re m a inly distributed in express business covered a rea, i t i s a hub betw een cust omers and express log istics net w ork, i t i s the m ost closely relat ionship w ith the cust omer.2 Ex press t ransit cent erFedEx t ransit node is mainly to ex press log istics net w ork of ex press dist ribution and transport. In the ex press indust ry g enerally call forw a r ding nodes distribution center.Dist ribution cent er is t hat i t i s import ant to ex press the import ance of sorting and dist ributing node,a l t houg h it i s not eng ag ed in com m o dit y concret e product ion,but i t carried from ot her outlet s to express according to the act ual sit uation of t heir concent rat ion,distribution and t ransport,so as to realize ex press process from scatt ered to cent ralized and decent ralized. La r g e ex p ress t ransit cent er a l s o know n as the reg ional hub, i s mainly responsible for an area of ex press distribution processing w ork. R eg ional hub locat ion and capacit y of the ent ire net w ork t ransit t ime and produce a g reat impact on the t ransport capacit y. Ex press delivery reg ional hub of the dist ribution cent er,unified handling aft er i t s focus to send to other reg i onal hub or sent to the affilia t e dist ribut ion cent ers.FedExt ransit cent er location,quantit y,and the det erminat ion of posit ion,usually to com prehensively consider the g oods cat eg ory, quant it y,flow,traffic condit ions,g eog r aphical location,t imeliness, urban planning and policy, a nd other t ransit cent er connect ing relat ions, operat ion efficiency and ot her fact ors.3 Ex press log i stics operation netw orkEx press operation of the net w ork i s m a inly composed of backbone t ransport netw ork, distribution netw ork and term inal to send t hree part s. A mong t hem , the backbone t ransport net w ork i s m a inly composed of reg ional hub and distribut ion cent er,dist ribut ion netw ork mainly distribution cent er and end node; from end off the net w ork by t he end of branches and cust omer focus point.U sually express log i st ics net w ork, the net w ork backbone netw ork st ruct ure for shaft ty pe netw ork, most ly adopt m ore hub shaft radial net w ork; From dist ribution net w ork and end off net w ork mainly based on the principle of reg ional scope of radiation distance and w i th the m ethod of part ition manag em ent. The ex press log istics net w ork is t he core part of the backbone transport net w ork; it is t he a ssurance of delivery tim eliness.B ackbone net w ork process i s conducted w i thin the ent erprise, the opt imizat ion of the backbone net w ork mainly from the perspect ive of the cost or e xpense. From end off netw ork because of c lose cont act w i th cust omers, i s express ent erprise and cust omer direct int eraction betw een the nodes, not only consider the cost on i ts optim izat ion int eg ra tion problems, should t hink more cust om ers w i th bet ter service ex perience for the m a in purpose, pay a ttention to the m ining of cust omer dem and information, optim ized and int eg rat ed send l ink.Delivery of the ent ire process is as follow s : w hen the c l ient needs to send a , can t hroug h the phone, the w ebsit e of C ourier company or to t he end node, send a request, a fter receiving member w i l l charg e customers express according to the s i t uat ion; R eceipt a t the end of the class member t ake the ex press m a i l delivery to the end node, w i l l ex press, document s and other inform a tion w i th the st aff of the t erm inal branch t ransfer processing , t hus completes a w a rehousing operat ions; Outlet s w arehouse controller according to the local dist ribut ion cent er a t the end of the t ransit fl ig hts w i l l express mail sent to the local dist ribut ion centers, i t i s called the sender homew ork; Express mail a rrived a t the dist ribut ion cent er, sorting , a l l ex press direct ion as conditions aft er sorting to a rrang e transportation a fter a brief st orag e ( depending on the sit uation on the mode of t ransport at ion to choose tra ins, cars, planes, et c.).A ft er the ex press arrival a t the reg ional hub of the c i ty, according to express the dest inat ion address ag a in point s to the dist ribut ion cent er, and t hen, t hroug h the dist ribution net w ork to send the g oods to the t erminal outlet s;译文快递物流网络优化研究Humble M摘要快递业作为现代物流业的重要组成部分成为最近几年发展最快的行业之一。

发酵剂在传统土耳其饮料boze中的应用摘要：Bose 系列饮料是由玉米、大米以及面粉用明串珠菌属、肠膜明串珠亚种、L. oenos、乳酸菌coryniformis、以及酿酒酵母和葡萄汁酵母发酵而来的。

这些乳酸菌和酵母分开或者混合接种到bosa 饮料中并在30℃发酵。

在发酵期间，PH、酸度以及菌种数量是有待确定的。

发酵结束后会做一些感官评价来确定最佳发酵参数。

酿酒酵母加肠膜明串珠亚种加L.confusus是bosa系列产品的最佳发酵剂。

boza生产总值成分和流变特性的测定使用这种最佳的组合是确定的。

本文主要介绍通过使用发酵剂来改善传统土耳其饮料（boza）的潜力。

关键词：boza、乳酸菌、酵母、谷物、发酵、感官评价1.引言Boza 是一种高粘度的经过发酵的传统土耳其饮料，他的制作原料是谷物如玉米、大米和小麦粉。

boza是由原料被混合乳酸菌和酵母经过自然发酵生产出来的。

发酵过程中微生物之间的相互作用不确定,导致产品的质量和稳定性的变化。

所以很有必要使用发酵剂来避免这种传统发酵产品的质量不稳定性。

使用发酵剂优化产品已经成功运用于一些发酵产品比如奶酪、泡菜、酸乳酪和啤酒中。

也有一些关于发酵剂的发展对其他谷物发酵食品（如加里）的研究。

尽管boza的微生物系列已经被报道出来，却没有有关boza饮料的发酵剂改善的研究。

本研究的主要目的是选择适当的发酵剂并使用感官评价组合以产生boza特征属性受控条件下没有质量的变化。

另外一个目的是测定boza 的总成分和流变性质并采用最佳的培养条件生产产品。

2.材料和方法生产boza系列的原材料是一些来自当地市场的玉米、大米、面粉以及白砂糖。

其他物料是一些化学分析试剂、8种乳酸菌和2种酵母菌。

3方法3.1 boza 麦芽汁的制备制备Boza使用玉米、小麦和大米面粉混合在2:1:1的比率，在其中加入一升的水并将其煮沸。

在连续搅拌的条件下让其沸腾20分钟左右，然后让其冷却，若有必要可以加一些水进行稀释。

本科毕业设计(论文) 外文翻译（附外文原文）系 ( 院 )：资源与环境工程系课题名称：英文翻译专业(方向)：环境工程班级：2004-1班学生：3040106119指导教师：刘辉利副教授日期：2008年4月20使用褐煤（一种低成本吸附剂）从酸性矿物废水中去除和回收金属离子a. 美国, 大学公园, PA 16802, 宾夕法尼亚州立大学, 能源部和Geo 环境工程学.b. 印度第80号邮箱, Mahatma Gandhi ・Marg, Lucknow 226001, 工业毒素学研究中心, 环境化学分部,于2006 年5月6 日网上获得，2006 年4月24 日接受，2006 年3月19 日;校正，2006 年2月15 日接收。

摘要酸性矿物废水(AMD), 是一个长期的重大环境问题，起因于钢硫铁矿的微生物在水和空气氧化作用, 买得起包含毒性金属离子的一种酸性解答。

这项研究的主要宗旨是通过使用褐煤（一种低成本吸附剂）从酸性矿水(AMD)中去除和回收金属离子。

褐煤已被用于酸性矿水排水AMD 的处理。

经研究其能吸附亚铁, 铁, 锰、锌和钙在multi-component 含水系统中。

研究通过在不同的酸碱度里进行以找出最适宜的酸碱度。

模拟工业条件进行酸性矿物废水处理, 所有研究被进行通过单一的并且设定多专栏流动模式。

空的床接触时间(EBCT) 模型被使用为了使吸附剂用量减到最小。

金属离子的回收并且吸附剂的再生成功地达到了使用0.1 M 硝酸不用分解塔器。

关键词:吸附; 重金属; 吸附; 褐煤; 酸性矿物废水处理; 固体废料再利用; 亚铁; 铁; 锰。

文章概述1. 介绍2. 材料和方法2.1. 化学制品、材料和设备3. 吸附步骤3.1. 酸碱度最佳化3.2. 固定床研究3.2.1 单一栏3.2.2 多栏4. 结果和讨论4.1. ZPC 和渗析特征4.2 酸碱度的影响4.3. Multi-component 固定吸附床4.3.1 褐煤使用率4.4. 吸附机制4.5. 解吸附作用研究5. 结论1. 介绍酸性矿物废水(AMD) 是一个严重的环境问题起因于硫化物矿物风化, 譬如硫铁矿(FeS2) 和它的同素异形体矿物(α-FeS) 。

文献出处 : Humble M . The study of ex press log i stics netw ork optimization [ J ] . Operations R esearch Perspectives, 2016 , 6 ( 3) : 106 -115 .原文The study of ex press log istics netw ork optim izationHumble MA bstractEx press industry as an important part of m odern log istics industry to become one of the fastest g row ing industries in recent y ears. The rapid development of ex press industry lead to a lot of capital inflow ex press delivery m arket, thus express companies, there are many sizes for g rab market resources, the com petition betw een enterprises is becoming more and fiercer. Ex cessive com petition caused a lot of w aste of resources, reduce the utilization of resources, and increase the cost of log i stics. In order to solve these problems need to integ ra te the express industry resources, increase the concentration of industry level. A nd C ourier companies merg ers and reorg anization is the integ ration betw een the express industry resources, ex press delivery industry competitiveness effective w a y. Express log i stics netw ork in the ex press industry i s reg arded as ex press the l ifeblood of enterprises, of w hich the end of the service netw ork (hereinafter referred to as end nodes), the distribution center, the urban reg ional hub ( hereinafter referred to as the reg ional hub) and the num ber of spatial lay out directly determines the operation m ode of delivery a nd quality of operations. Therefore, under the merg er restructuring enterprises express log i stics netw ork optim ization integ ration to ex press the development of the enterprise after the m erg er and reorg anization play s a decisive role.Key w ords: M erg ers and reorg anization; Netw ork optimization integ ra tion; End node; Distribution center1 IntroductionLog is tics netw ork theory is the inevitable outcome of the development of log istics manag ement research Gum constantly, is a standardized, sy stematic and scientific research important w a y of m odern log istics, i t ex panded the log i stics netw ork operations research new tra in of thoug ht, provides a theoretical basis for the log i stics netw ork optim ization. DJ B ow ers ( 2007 ) put forw ard the theory of supply chain log istics integ ra tion, and based on log istics, w a rehouse location, transportation cost, inventory cost, e tc , integ ra ting advanced the theory of integ rationa rchitecture. M S R am m . ( 2009 ) integ ra ted log i stics netw ork i s a c losed loop integ rated forw ard/re verse log i stics netw ork, including production/re covery, m ix ed distribution, custom ers, collecting and processing center, etc., first used to determine the m ix ed integ er linear prog ram m ing model for log i stics netw ork integ ration, and then in uncertain scenarios using the mix ed integ er l inear prog ram ming model, the model can avoid suboptimal results caused by separation and continuous. M a ria B oiler mud ( 2013 ) in a nonlinear integ er model to solve the dy namic integ ra ted forw ard and reverse distribution netw ork desig n model double H standards to minim ize transport costs a nd tim e; Integ ra ted log i stics netw ork facility location problem to improve the efficiency of forw ard and reverse log istics, mainly i s the determ ination of three ty pes of facilities, w arehouse ( log i stics), collection centers ( reverse log i stics) and mix ed facilities ( forw ard and reverse log istics).2Ex press log istics netw ork2.1 1 S ummary of log i stics netw orkDonald j . B ow er and David i ts loss in the book of the process of log i stics m anag ement, supply chain integ ration points out that the w hole log i stics netw ork desig n has a direct impact on the log i stics efficiency, to provide customer service capabilities and cost mainly by num ber of log i stics facilities, the influence of the practical factors such as scale; Essential part of netw ork la y out desig n i s to determ ine the num ber of every k ind of facilities, location and job, etc.; In the constantly chang ing competitive environment, the ty pes of products, customer dema nd chang es a t the mom ent, so perfecting the infrastructure netw ork to adapt to the chang e of supply and demand i s very important. R onald h. B a l loon ( 2010 ) arg ues that the essence of the netw ork structure problem i s to determine from to the customer's netw ork structure, including the facility ty pe, num ber, location and each facility betw een the determ ination of amount of products and custom ers; In his book "log istics manag ement", l ists the data needed for log i stics netw ork integ ration, and put forw ard the evaluation and the evaluation of enterprise log istics netw ork in the g eneral audit criteria. L og i stics netw ork has the follow ing characteristics: log i stics netw ork has the characteristics of hig h efficiency. The g oal of log i stics netw ork is the low est cost for a shorter time w ould be delivered g oods in g ood condition of the demand s ide, the max imum com bination of log i stics and inform a tion flow, cash flow to achieve "zero inventory, a short period of time, no interm i ttent transmission" i s the ideal state. The openness of the log i s tics i s netw ork. Openness i sthe foundation of log i stics nodes can be throug h the public netw ork, a ll nodes connected directly or indirectly. L og i stics netw ork openness enables each node and other nodes ex chang e information quickly, processing business. Pilot log i s tics netw ork inform a tion.W idespread use of mechanization and automation equipment can g reatly improve the level of inform a tion of log i stics netw ork, but the collection, manag ement, analy sis and m ining equipm ent in the process of log i stics information i s more important. The information in the log istics netw ork throug hout the log istics activity a lw a y s , to the operation of log istics netw ork as a w hole have the function of the g uidance and integ ra tion. Log istics netw ork has the s ize advantag e . S cale i s the important a ims of log i stics netw ork. Dispersion formed in the fie ld of log i stics, log i stics netw ork nodes and the characteristic of manag ement, w i l l hig hlig ht i ts scale advantag e . Throug h la rg e-scale joint operation of log istics nodes can fully improve the effic iency of the w hole operation of the log i stics netw ork, reduce the cost of the overall operation, reliance on a sing le node of log i stics netw ork is a l so s ig nificantly reduced; C an't w ork normally even if there i s a node, other nodes can quickly m ak e up for i t, resist risk ability.2.2 2 The characteristics of the ex press log istics netw orkEx press log i stics netw ork m a inly includes three parts, main transport netw orks, and distribution netw orks, from end off. Every part of the netw ork composition and the exercise of the functions of each are not identical. B ackbone transport netw ork i s ma inly betw een reg ional hub and reg ional hub and distribution center of the netw ork, i t i s ma inly long distance transportation, mainly by car and a i r transport w a y. Distribution netw ork is mainly betw een distribution center and end node netw ork, g oods distribution throug h the distribution centers, arrived a t the end of the subordinate branches. From end off netw ork composed of customers and end node, i t i s the first l ink i s the final l ink of express delivery business, is a lso an im portant part of the customer experience.The different methods of delivery of g oods produced tw o ty pes of netw orks: shaft ty pe and the entire company g eneral form ula ex press log i stics netw ork. A m ong them, the major structure of the radiation i s the hub of partition netw ork characteristics, in each partition can have one or more of the hub, the hub node can not only send and receive the g oods w i thin the reg ion but a l so can connect other areas of the hub node, transit and sorting is a l so i ts function. In the ax i s of the ty pe express log i stics netw ork, transport of g oods need to transport to the hub node, throug h sortingtransit hub node before handing out again. Fully connected netw ork i s any node is ex chang ed betw een, should have the shipping l ine directly connected. The connected netw ork can realize g oods direct ty pe distribution betw een any nodes on the netw ork, but this w a y of distribution w i l l be an additional shipping cost. B ecause of the dispersed distribution and sm a l l features express C ourier companies i s the main distribution object, so ax ia l radial express m ore than log istics netw ork a l l over a long w i th the netw ork helps to improve log istics resources integ ra tion, log istics resource utilization, to reduce log i stics cost, shaft f ty pe ex press log i stics netw ork more in l ine w i th the actual situation of delivery operation.3The com position of ex press log i s tics netw ork3 .1 Delivery terminal netw orkDelivery a t the end of the node is the beg inning of the express log i stics netw ork point and end point, its main function i s to Posting and expresses m a i l delivery. End points a re m a inly distributed in express business covered a rea, i t i s a hub betw een customers and express log istics netw ork, i t i s the m ost closely relationship w ith the customer.3.2 2 Ex press transit centerFedEx transit node is mainly to ex press log istics netw ork of ex press distribution and transport. In the ex press industry g enerally call forw a rding nodes distribution center. Distribution center is that i t i s important to ex press the importance of sorting and distributing node, a lthoug h it i s not eng ag ed in com m odity concrete production, but i t carried from other outlets to express according to the actual situation of their concentration, distribution and transport, so as to realize ex press process from scattered to centralized and decentralized. La rg e ex press transit center a l s o know n as the reg ional hub, i s mainly responsible for an area of ex press distribution processing w ork. R eg ional hub location and capacity of the entire netw ork transit time and produce a g reat impact on the transport capacity. Ex press delivery reg ional hub of the distribution center, unified handling after i t s focus to send to other reg ional hub or sent to the affilia te distribution centers. FedEx transit center location, quantity, and the determination of position, usually to com prehensively consider the g oods categ ory, quantity, flow, traffic conditions, g eog raphical location, timeliness, urban planning and policy, a nd other transit center connecting relations, operation efficiency and other factors.3.3 3 Ex press log i stics operation netw orkEx press operation of the netw ork i s m a inly composed of backbone transport netw ork, distribution netw ork and term inal to send three parts. A mong them , the backbone transport netw ork i s m a inly composed of reg ional hub and distribution center, distribution netw ork mainly distribution center and end node; from end off the netw ork by the end of branches and customer focus point. U sually express log i stics netw ork, the netw ork backbone netw ork structure for shaft ty pe netw ork, mostly adopt m ore hub shaft radial netw ork; From distribution netw ork and end off netw ork mainly based on the principle of reg ional scope of radiation distance and w i th the m ethod of partition manag em ent. The ex press log istics netw ork is the core part of the backbone transport netw ork; it is the assurance of delivery tim eliness. B ackbone netw ork process i s conducted w i thin the enterprise, the optimization of the backbone netw ork mainly from the perspective of the cost or expense. From end off netw ork because of c lose contact w i th customers, i s express enterprise and customer direct interaction betw een the nodes, not only consider the cost on i ts optim ization integ ra tion problems, should think more custom ers w i th better service ex perience for the m a in purpose, pay a ttention to the m ining of customer dem and information, optim ized and integ rated send l ink.Delivery of the entire process is as follow s : w hen the c l ient needs to send a , can throug h the phone, the w ebsite of C ourier company or to the end node, send a request, a fter receiving member w i l l charg e customers express according to the s i tuation; R eceipt a t the end of the class member take the ex press m a i l delivery to the end node, w i l l ex press, documents and other inform a tion w i th the staff of the term inal branch transfer processing , thus completes a w a rehousing operations; Outlets w arehouse controller according to the local distribution center a t the end of the transit fl ig hts w i l l express mail sent to the local distribution centers, i t i s called the sender homew ork; Express mail a rrived a t the distribution center, sorting , a l l ex press direction as conditions after sorting to a rrang e transportation a fter a brief storag e ( depending on the situation on the mode of transportation to choose tra ins, cars, planes, etc.).A fter the ex press arrival a t the reg ional hub of the c i ty, according to express the destination address ag a in points to the distribution center, and then, throug h the distribution netw ork to send the g oods to the terminal outlets;译文快递物流网络优化研究Humble M摘要快递业作为现代物流业的重要组成部分成为最近几年发展最快的行业之一。

外文文献翻译（附原文）外文译文一：产业集群的竞争优势——以中国大连软件工业园为例Weilin Zhao,Chihiro Watanabe，Charla-Griffy-Brown[J]. Marketing Science,2009(2):123-125.摘要：本文本着为促进工业的发展的初衷探讨了中国软件公园的竞争优势。

产业集群深植于当地的制度系统，因此拥有特殊的竞争优势。

根据波特的“钻石”模型、SWOT模型的测试结果对中国大连软件园的案例进行了定性的分析。

产业集群是包括一系列在指定地理上集聚的公司，它扎根于当地政府、行业和学术的当地制度系统，以此获得大量的资源，从而获得产业经济发展的竞争优势。

为了成功驾驭中国经济范式从批量生产到开发新产品的转换，持续加强产业集群的竞争优势,促进工业和区域的经济发展是非常有必要的。

关键词：竞争优势；产业集群；当地制度系统；大连软件工业园；中国；科技园区；创新；区域发展产业集群产业集群是波特[1]也推而广之的一个经济发展的前沿概念。

作为一个在全球经济战略公认的专家,他指出了产业集群在促进区域经济发展中的作用。

他写道：集群的概念,“或出现在特定的地理位置与产业相关联的公司、供应商和机构，已成为了公司和政府思考和评估当地竞争优势和制定公共决策的一种新的要素。

但是，他至今也没有对产业集群做出准确的定义。

最近根据德瑞克、泰克拉[2]和李维[3]检查的关于产业集群和识别为“地理浓度的行业优势的文献取得了进展”。

“地理集中”定义了产业集群的一个关键而鲜明的基本性质。

产业由地区上特定的众多公司集聚而成,他们通常有共同市场、,有着共同的供应商,交易对象,教育机构和其它像知识及信息一样无形的东西，同样地,他们也面临相似的机会和威胁。

在全球产业集群有许多种发展模式。

比如美国加州的硅谷和马萨诸塞州的128鲁特都是知名的产业集群。

前者以微电子、生物技术、和风险资本市场而闻名,而后者则是以软件、计算机和通讯硬件享誉天下[4]。

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。

外文原文：Rolling Contact BearingsThe concern of a machine designer with ball and roller bearings is five fold as follows:(a) life in relation to load; (b) stiffness, i. e. deflections under load; (c) friction;(d) wear; (e) noise. For moderate loads and speeds the correct selection of a standard bearing on the basis of load rating will become important where loads are high, although this is usually of less magnitude than that of the shafts or other components associated with the bearing. Where speeds are high special cooling arrangements become necessary which may increase frictional drag. Wear is primarily associated with the introduction of contaminants, and sealing arrangements must be chosen with regard to the hostility of the environment.Because the high quality and low price of ball and roller bearings depends on quantity production, the task of the machine designer becomes one of selection rather than design. Rolling-contact bearings are generally made with steel which is through-hardened to about 900 HV, although in many mechanisms special races are not provided and the interacting surfaces are hardened to about 600 HV. It is not surprising that, owing to the high stresses involved, a predominant form of failure should be metal fatigue, and a good deal of work is based on accepted values of life and it is general practice in the bearing industry to define the load capacity of the bearing as that value below which 90 per cent of a batch will exceed a life of one million revolutions.Notwithstanding the fact that responsibility for the basic design of ball and roller bearings rests with the bearing manufacturer, the machine designer must form a correct appreciation of the duty to be performed by the bearing and be concerned not only with bearing selection but with the conditions for correct installation.The fit of the bearing races onto the shaft or onto the housings is of critical importance because of their combined effect on the internal clearance of the bearing as well as preserving the desired degree of interference fit. Inadequate interference can induce serious trouble from fretting corrosion. The inner race is frequently located axially by abutting against a shoulder. A radius at this point is essential for the avoidance of stress concentration and ball races are provided with a radius or chamfer to allow space for this.Where life is not the determining factor in design, it is usual to determine maximum loading by the amount to which a bearing will deflect under load. Thus the concept of “static load-carrying capacity” is understood to mean the load that can be applied to a bearing, which is either stationary or subject to slight swiveling motions, without impairing its running qualities for subsequent rotational motion. This has been determined by practical experience as the load which when applied to a bearing results in a total deformation of the rolling-element diameter. This would correspond to a permanent deformation of 0.0025 mm for a ball 25 mm in diameter.The successful functioning of many bearings depends upon providing them with adequate protection against their environment, and in some circumstances the environment must be protected from lubricants or products of deterioration of the bearing design. Moreover, seals which are applied to moving parts for any purpose are of interest to tribologists because they are components of bearing systems and can only be designed satisfactorily on the basis of the appropriate bearing theory.Notwithstanding their importance, the amount of research effort that has been devoted to the understanding of the behavior of seals has been small when compared with that devoted to other aspects of bearing technology.LathesLathes are widely used in industry to produce all kinds of machined parts. Some are general purpose machines, and others are used to perform highly specialized operations.Engine LathesEngine lathes, of course, are general-purpose machine used in production and maintenance shop all over the world. Sizes range from small bench models to huge heavy duty pieces of equipment. Many of the larger lathes come equipped with attachments not commonly found in the ordinary shop, such as automatic stops for the carriage.Tracer or Duplicating LathesThe tracer or duplicating lathe is designed to produce irregularly shaped parts automatically. The basic operation of this lathe is as fallows. A template of either a flat or three-dimensional shape is placed in a holder. A guide or pointer then moves alongthis shape and its movement controls that of the cutting tool. The duplication may include a square or tapered shoulder, grooves, tapers, and contours. Work such as motor shafts, spindles, pistons, rods, car axles, turbine shafts, and a variety of other objects can be turned using this type of lathe.Turret LathesWhen machining a complex workpiece on a general-purpose lathe, a great deal of time is spent changing and adjusting the several tools that are needed to complete the work. One of the first adaptations of the engine lathe which made it more suitable to mass production was the addition of multi-tool turret in place of the tailstock. Although most turrets have six stations, some have as many as eight.High-production turret lathes are very complicated machines with a wide variety of power accessories. The principal feature of all turret lathes, however, is that the tools can perform a consecutive serials of operations in proper sequence. Once the tools have been set and adjusted, little skill is required to run out duplicate parts.Automatic Screw MachinesScrew machines are similar in construction to turret lathes, except that their heads are designed to hold and feed long bars of stock. Otherwise, there is little different between them. Both are designed for multiple tooling, and both have adaptations for identical work. Originally, the turret lathe was designed as a chucking lathe for machining small castings, forgings, and irregularly shaped workpieces.The first screw machines were designed to feed bar stock and wire used in making small screw parts. Today, however, the turret lathe is frequently used with a collet attachment, and the automatic screw machine can be equipped with a chuck to hold castings.The single-spindle automatic screw machine, as its name implies, machines work on only one bar of stock at a time. A bar 16 to 20 feet long is fed through the headstock spindle and is held firmly by a collect. The machining operations are done by cutting tools mounted on the turret and on the cross slide. When the machine is in operation, the spindle and the stock are rotated at selected speeds for different operations. If required, rapid reversal of spindle direction is also possible.In the single-spindle automatic screw machine, a specific length of stock is automatically fed through the spindle to a machining area. At this point, the turret andcross slide move into position and automatically perform whatever operations are required. After the machined piece is cut off, stock is again fed into the machining area and the entire cycle is repeated.Multiple-spindle automatic screw machines have from four to eight spindles located around a spindle carrier. Long bars of stock, supported at the rear of the machine, pass through these hollow spindles and are gripped by collets. With the single spindle machine, the turret indexes around the spindle. When one tool on the turret is working, the others are not. With a multiple spindle machine, however, the spindle itself indexes. Thus the bars of stock are carried to the various end working and side working tools. Each tool operates in only one position, but all tools operate simultaneously. Therefore, four to eight workpieces can be machined at the same time.Vertical Turret LathesA vertical turret lathe is basically a turret lathe that has been stood on its headstock end. It is designed to perform a variety of turning operations. It consists of a turret, a revolving table, and a side head with a square turret for holding additional tools. Operations performed by any of the tools mounted on the turret or side head can be controlled through the use of stops.Machining CentersMany of today’s more sophisticated lathes are called machining centers since they are capable of performing, in addition to the normal turning operations, certain milling and drilling operations. Basically, a machining center can be thought of as being a combination turret lathe and milling machine. Additional features are sometimes included by manufacturers to increase the versatility of their machines.Numerical ControlOne of the most fundamental concepts in the area of advanced manufacturing technologies is numerical control (NC). Prior to the advent of NC, all machine tools were manually operated and controlled .Among the many limitations associated with manual control machine tools, perhaps none is more prominent than the limitation of operator skills. With manual control, the quality of the product is directly related to and limited to the skills of the operator. Numerical control represents the first majorstep away from human control of machine tools.Numerical control means the control of machine tools and other manufacturing systems through the use of prerecorded, written symbolic instructions. Rather than operating a machine tool, an NC technician writes a program that issues operational instructions to the machine tool. For a machine tool to be numerically controlled, it must be interfaced with a device for accepting and decoding the programmed instructions, known as a reader.Numerical control was developed to overcome the limitation of human operators, and it has done so. Numerical control machines are more accurate than manually operated machines, they can produce parts more uniformly, they are faster, and the long-run tooling costs are lower. The development of NC led to the development of several other innovations in manufacturing technology:1.Electrical discharge machining.ser cutting.3.Electron beam welding.Numerical control has also made machine tools more versatile than their manually operated predecessors. An NC machine tool can automatically produce a wide variety of parts, each involving an assortment of widely varied and complex machining processes. Numerical control has allowed manufacturers to undertake the production of products that would not have been feasible from an economic perspective using manually controlled machine tools and processes.Like so many advanced technologies, NC was born in the laboratories of the Massachusetts Institute of Technology. The concept of NC was developed in the early 1950s with funding provided by the U. S. Air force. In its earliest stages, NC machines were able to make straight cuts efficiently and effectively.However, curved paths were a problem because the machine tool had to be programmed to undertake a series of horizontal and vertical steps to produce a curve. The shorter is the straight lines making up the steps, the smoother is the curve. Each line segment in the steps had to be calculated.This problem led to the development in 1959 of the Automatically Programmed Tools (APT) language. This is a special programming language for NC that uses statements similar to English language to define the part geometry, describe the cutting tool configuration, and specify the necessary motions. The development of the APT language was a major step forward in the further development of NC technology.The original NC systems were vastly different from those used today. The machines had hardwired logic circuits. The instructional programs were written on punched paper, which was later to be replaced by magnetic plastic tape. A tape reader was used to interpret the instructions written on the tape for the machine. Together, all of this represented a giant step forward in the control of machine tools. However, there were a number of problems with NC at this point in its development.A major problem was the fragility of the punched paper tape medium. It was common for the paper tape containing the programmed instructions to break or tear during a machining process. This problem was exacerbated by the fact that each successive time a part was produced on a machine tool, the paper tape carrying the programmed instructions had to be rerun through the reader. If it was necessary to produce 100 copies of a given part, it was also necessary to run the paper tape through the reader 100 separate times. Fragile paper tapes simply could not withstand the rigors of a shop floor environment and this kind of repeated use.This led to the development of a special magnetic plastic tape. Whereas the paper tape carried the programmed instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of holes punched in the tape, the plastic tape carried the instructions as a series of magnetic dots. The plastic tape was much stronger than the paper taps, which solved the problem of frequent tearing and breakage. However, it still left two other problems.The most important of these was that it was difficult or impossible to change the instructions entered on the tape. To make even the most minor adjustments in a program of instructions, it was necessary to interrupt machining operations and make a new tape .It was also still necessary to run the tape through the reader as many times as there were parts to be produced. Fortunately, computer technology became a reality and soon solved the problems of NC associated with punched paper and plastic tape.The development of a concept known as direct numerical control (DNC) solved the paper and plastic tape problems associated with numerical control by simply eliminating tape as the medium for carrying the programmed instructions. In direct numerical control .machine tools are tied, via a data transmission link, to a host computer. Programs for operating the machine tools are stored in the host computer and fed to the machine tool as needed via the data transmission linkage. Direct numerical control represented a major step forward over punched tape and plastic tape. However, it is subject to the same limitations as all technologies that depend on a hostcomputer. When the lost computer goes down, the machine tools also experience downtime. This problem led to the development of computer numerical control.The development of the microprocessor allowed for the development of programmable logic controllers (PLCs) and microcomputers. These two technologies allowed for the development of computer numerical control (CNC).With CNC, each machine tool has a PLC or a microcomputer that serves the same purpose. This allows programs to be input and stored at each individual machine tool. It also allows programs to be developed off-line and downloaded at the individual machine tool. CNC solved the problems associated with downtime of the host computer, but it introduced another known as data management. The same program might be loaded on ten different microcomputers with no communication among them. This problem is in the process of being solved by local area networks that connect microcomputers for better data manageme中文译文：滚动轴承对于球轴承和滚子轴承，一个机器设计人员应该考虑下面五个方面：（a）寿命与载荷的关系；（b）刚度，也就是在载荷作用下的变形；（c）摩擦；（d）磨损；（e）噪声。