英文演讲文章（精选6篇）
1.先找5篇跟自己论文最相关的外文文章，花一个月的时间认认真真的看，反复看，要求全部读懂，不懂的地方可以和同学和老师交流一下。一个月以后你已经上路了。
2.如何读标题：不要忽视一篇论文的标题，看完标题以后想想要是让你写你怎么用一句话来表达这个标题，根据标题推测一下作者论文可能是什么内容。有时候一句比较长的标题让你写，你可能还不会表达。下次你写的时候就可以借鉴了
3.如何读摘要：快速浏览一遍，这里主要介绍这篇文章做了些什么。也许初看起来不好理解，看不懂，这时候不要气馁，不管它往下看，等你看完这篇文章的时候也许你都明白了。因为摘要写的很简洁，省略了很多前提和条件，在你第一眼看到摘要而不明白作者意图的时候看不懂是正常的。
4.如何读引言（前言）：当你了解了你的研究领域的一些情况，看引言应该是一件很容易的事情了，都是介绍性的东西，写的应该都差不多，所以看文献多了以后看这部分的内容就很快了，一扫而过。有些老外写得很经典得句子要记下了，下次你写就可以用了。
5.如何读材料及试验：当你文献看多了以后，这部分内容也很简单了，无非就是介绍试验方法，自己怎么做试验的。很快就能把它看完了吧
6.如何看试验结果：看结果这部分一定要结合结果中的图和表看，这样看的快。主要看懂试验的结果，体会作者的表达方法（例如作者用不同的句子结构描述一些数字的结果）。有时看完以后再想想：就这么一点结果，别人居然可以大篇幅的写这么多，要是我可能半页就说完了？
7.如何看分析与讨论：这是一篇文章的重点，也是最花时间的。我一般把前面部分看完以后不急于看分析讨论。我会想要是我做出来这些结果我会怎么来写这部分分析与讨论呢？然后慢慢看作者的分析与讨论，仔细体会作者观点，为我所用。当然有时候别人的观点比较新，分析比较深刻，偶尔看不懂也是情理之中。当你看的多了，你肯定会看的越来越懂，自己的idea越来越多
8.如何看结论：这个时候看结论就一目了然了，作后再反过去看看摘要，其实差不多
9.把下载的论文打印出来，根据与自己课题的相关性分三类，一类要精读，二类要泛读，三类要选择性的读。分别装订在一起
10.看完的文献千万不要丢在一边不管，3－4个月一定要温习一遍，可以根据需要，对比自己的试验结果来看
11.学会记笔记，重要的结论，经典的句子，精巧的试验方案一定要记下来，供参考和学习
12.有些试验方法相同，结论不同的文献，可以批判性的阅读。我想要是你自己做试验多的话，你应该有这个能力判断谁的更对一点。出现试验方法相同，结论不同的原因有下：试验方法描述不详细，可能方法有差别；试验条件不一样；某些作者夸大结果，瞎编数据
韩礼德 (1970, 1973, 1985/1994/2004) 把语言的纯理功能分成三种:概念元功能 (ideational function) 、人际元功能 (interpersonal function) 和语篇元功能 (textual function) 。而韩礼德所说的概念功能包括经验功能和逻辑功能两个部分。经验功能指的是语言对人们在现实世界 (包括内心世界) 中各种经历的表达。换言之, 就是反映客观世界和主观世界中所发生的事, 所牵涉的人和物以及与之有关的时间、地点等环境因素。逻辑功能指的则是语言对两个或两个以上的意义单位之间逻辑关系的表达。 (胡壮麟, 朱永生, 张德禄, 李占子, 2005:74)
经验功能主要是通过“及物性” (transitivity) 和“语态” (voice) 得到体现的。人际功能主要通过语气系统和情态系统来体现, 而情态系统所表达的意义是从说话者的角度对命题的成功性和有效性所做出的判断, 或在命令中要求对方承担的义务和在提议中要表达的个人意愿。
功能语言学认为任何选择都是有意义的。“选择就是意义”是一条广泛应用的原则。形式是意义的体现, 形式不同, 表达的意义就不一样。在英语政治演讲的演讲稿的语篇中, 演讲者因为所要表达的政治观点, 意识形态的需要, 以及其演讲过程中相关的“参加者” (participant) 和“环境成分” (circumstantial element) 的不同, 所以演讲者在撰写政治演讲稿时对其语言要有所选择, 如及物过程类型的选择, 选择不同的及物性情态量值, 语篇衔接方式, 就意味着表达不同的意义, 撰稿者需要反复考虑琢磨怎样措辞怎样组织篇章结构才能使使信息更容易为听众所接受, 从而增加信息被听众认可的机会, 以便更有效地达到其政治目的。不同的英语政治演讲稿因其演讲者的身份, 演讲目的, 演讲的内容的不同, 其语言必有各自不同的特征, 但是其语言使用特征上在某些方面却存在共性, 现在我们以以色列总理伊扎克·拉宾1995年11月4日的最后一次演讲《要和平, 不要暴力!》为语料对其及物性、情态动词、语篇衔接词分别进行分析。《要和平, 不要暴力!》这篇演讲稿出自由高等教育出版社出版的《大学体验英语的综合教程3》 (第二版) 的第八单元的passsge B。
二、政治演讲
通常情况下, “演讲”和“演说”被人们视作同义。所谓的演讲, 是“在特定的时空环境中, 以有声语言和相应的体态语言为手段, 公开向听众传递信息, 表述见解, 阐明事理, 抒发感情, 以期达到感召听众的目的” (李元授、邹昆山2003:4-5) 。
政治演讲是“指人们针对国家内政事务和对外关系, 表明立场、阐明观点、宣传主张的一种演讲” (李元授, 周昆山2003:29) 。政府首脑的竞选演讲、施政演讲、就职演讲, 各级领导宣传大政方针和实施计划的演讲, 以及人们在政治集会上代表一定阶级, 政党或个人发表的演讲等, 都是政治演讲 (ibid:29-300) 。
在具体的演讲活动中, 演讲者以各种身份登场, 带有各种各样的演讲目的, 演讲的内容包罗万象。根据演讲的内容来分, 演讲可以分为政治演讲、学术演讲、生活演讲、法庭演讲、宗教演讲等五种类型 (邵守义1991;49) 。由于篇幅有限, 本文仅以以色列总理伊扎克·拉宾1995年11月4日的最后一次演讲《要和平, 不要暴力》作为英语政治演讲的语料进行分析。
三、伊扎克·拉宾的《要和平, 不要暴力!》英语政治演讲稿的微观语言特征
1、及物性分析
及物性是英语中表现概念功能的一个语义系统, 其作用在于把人们在现实世界的中的所见所闻, 所作所为分成若干种“过程” (process) , 并指明与各种有关的“参加者” (participant) 和“环境成分” (circumstantial element)
及物性包括六种不同的过程: (1) 物质过程 (material process) ; (2) 心理过程 (mental process) ; (3) 关系过程 (relational process) ; (4) 行为过程 (behavioral process) ; (5) 言语过程 (verbal process) 和 (6) 存在过程 (existential process) 。
通过对伊扎克·拉宾的《要和平, 不要暴力!》的英语演讲稿中各小句进行及物性分析, 我们发现六个过程类型出现了五个过程类型, 其中行为过程没有出现, 其他五个过程出现的频率大不相同, 现统计如下:
《要和平, 不要暴力!》英语政治演讲稿的及物性分析
从上面的表格中我们可以看到, 用的最多的过程类型是物质过程 (41, 43.6%) , 其次是关系过程 (28, 29.8%) , 物质过程和关系过程占总的物质过程类型 (69, 73.4%) 。心理过程排第三位 (14, 14.9%) 。第四位是存在过程 (6, 6.4%;) , 最后一位是言语过程 (5, 5.3%) , 行为过程没有用到。在伊扎克·拉宾的《要和平, 不要暴力!》的英语政治演讲稿中, 伊扎克·拉宾对物质过程和关系过程的使用比例相对大于其他过程, 过程类型呈现上述分布比例的原因是因为一篇强有力的演讲稿以客观地陈述事实, 合理的逻辑结构, 或强烈的情感表达为基础的。
将物质过程运用于英语政治演讲中, 尤其象伊扎克·拉宾《要和平, 不要暴力!》的英语政治演讲稿具有说服性的政治演讲, 通过物质过程向听众展示民众及演讲者本人对和平的向往, 对暴力的痛恨。号召鼓动听众起来采取行动。伊扎克·拉宾通过物质过程的使用清楚地阐明自己的目标, 而不至使听众困惑。
2、情态分析:情态量值
Quirk等人 (1985:219) 把情态看作是演讲者对命题的真实性的判断。在客观上, 真实性存在归一性 (polarity) , 非此即彼。Halliday把情态和归一性联系在一起, 认为情态指的是“是”与“非”之间的意义领域, 即肯定和肯定之间的中间区域。既然情态表达的是肯定和否定意义之间的中间区域, 所以演讲者可以在肯定和否定之间通过不同的情态词把他的命题表达的更趋于肯定或否定。不同点情态动词通过其具有的不同的量值可以表达不同的程度的可能性、经常性、义务和意愿。
在任何语篇中情态动词 (如will, should, could, can等) 是实现情态化的方式之一。情态量词大致可分为高、中、低三级。下面表格是情态动词must, need, will, would, shall, should, may, can, be able to的情态量值 (Holliday 1994:362;2004:624) :
在伊扎克·拉宾《要和平, 不要暴力!》的英语政治演讲稿中总共有3个情态动词出现, 分别是will、must, can, 每个情态动词的出现频率如下:
从表中可以看出will作为情态动词出现的频率最高 (7, 63.3%) , 其次是can, must, (3, 27.3%;2, 18.1%;) 。伊扎克·拉宾用限定性情态动词, 且是中量值的情态动词will来表达实现以巴和平进程的概率, 即用情态动词表达可能性, 政治演讲家用情态动词来表达可能性可以看作是运用了礼貌原则中的一种礼貌策略。因为情态表达是肯定和否定之间的中间区域, 所以情态的使用是避免将事情绝对化的一种方式, 从而使听众更愿意接受政治家们所传递的信息, 这样就会增加听众认可信息的机会, 避免听众对其主张或观点挑战和批评, 最终与听众产生情感上的共鸣, 一起为共同的目标而努力。
在《要和平, 不要暴力!》中作者用高量值的限定性情态动词must来说明在现实生活中, 整个以色列人, 所有犹太教民, 许多阿拉伯世界人民, 全世界的人民的为争取和平, 反对暴力和恐怖主义所承担的义务。在英语政治演讲中有较多用高量值的情态词来表达义务的现象, 因为强有力的鼓动力量需要蕴涵于英语政治演讲中。政治演讲者在演讲过程中, 或鼓动, 或宣传, 或批驳, 这都需要引起听众的强烈的共鸣, 需要有强有力的鼓动性和号召性, 需要表达政治演讲家为了实现某个目标承担的责任和义务。比如美国总统通常在其就职演说中表达与其人民的共同的美好希望和英雄梦想, 并展示其雄才大略和施政纲领, 除此之外, 总统们往往要表达为了实现其英雄梦想和远大宏伟的目标自己和全国人民应该承担的责任。
演讲稿作者用can, 说明实现巴以和平进程的潜在性与能力。鉴于从语义上讲, 表潜在性的成分任隶属与情态系统, 韩礼德视其为情态的另一种类型。在英语中, 潜在性可分为三类:非明确主观取向, 由can来体现 (无明确主观取向) ;非明确客观取向, 由be able to来体现;明确客观取向, 由it is possible (for) 来体现 (胡壮麟朱永生, 张德禄, 李占子, 2005:152) 。
在伊扎克·拉宾《要和平, 不要暴力!》的英语政治演讲稿我们可以找到用低量值, possble表示可能性, 如:
1、it will be possible to make peace. (明确客观表可能性)
2、But, more than anything, in the more thanthree years of this Government’s existence, the Israeli people has proven that it is possible (明确客观表可能性) to make peace, that peace opens the door to a better economy and society;that peace is not just a prayer
还出现用动词表达情态意义, 这可用来表达作者本人的主观性, 具有明确主观取向。例如:
1、I have always believed (明确主观) that the majority of the people want peace and are ready totake risks for peace.
2、I believe that there is now a chance for peace, a great chance. (明确主观)
3、衔接连贯分析:词汇衔接
(1) 词汇衔接的定义
Halliday&Hasan合著的《英语的衔接》 (1976) 认为衔接手段大致可分为语法衔接和词汇衔接两种。其中, 词汇衔接 (lexical cohesion) 是指通过词汇语义的选择、组织和聚合, 建立起一定的语义衔接关系, 达到语篇连贯的目的。韩礼德在书中指出词汇衔接即“用词汇复现、近义词、上义词及其他语义关系把篇章中的句子连接起来……语篇的主题是由词汇衔接的贯通而得到实现的” (1976) 。英国另一位应用语言学家Hoey (1991) 认为“词汇衔接是创造篇章织体的主要手段, 篇章的连贯在很大程度上依靠词汇关系的构造而产生, 篇章中的各个句子通过词汇语义关系得以相互联系, 使得对一个句子的解读除了依靠句法手段之外, 还必须依赖同一语篇中词汇项之间的语义关系”
(2) 词汇衔接的方式
黄国文先生 (2001) 在《语篇分析的理论与实践》一书中指出:词汇衔接指“通过词的重复、同义、反义、上下义、整体与部分等关系达到语义连贯”。
通过对《要和平, 不要暴力》演讲稿分析后我们会发现词汇衔接在其篇章中建立一个贯穿篇章的链条, 重复是其最主要的衔接方式。重复是在词汇衔接中最直接的方式是具有同样语义同一形式的词汇在同一语篇中反复出现。它与句法衔接中的重复不同。句法衔接强调同样结构的重复出现.词汇重复是一个单词或词组的重复。
在伊扎克·拉宾《要和平, 不要暴力!》演说中重复词或短语占很大的篇幅。如:peace, 26次;chance, 5次;democracy, 2次, democratic (形容词) 1次;election, 2次;violience3次;I want to 5次, possible to, 2次;more than, 2次;prayer, 2次;aspiration, 2次;partner, 2次;enemy, 2次;do one’s part, 2次;conflict, 2次;pain, 3次;path, 3次;a military man, 2次;here, 5次等等。
以色列列总理伊扎克·拉宾通过对关键词peace的26次重复使用及其他词的重复使用向听众阐明实现和平的重要性和意义, 并且代所有正义的听众表达了其渴望和平, 反对暴力的心声, 从而与听众在情感上产生共鸣, 抓住时机, 最终采取实现和平, 维护和平的行动, 达到通过演讲实现其政治目的。如的两次使用表明以伊扎克拉宾为代表的政治家们已经从事反对暴力, 实现和平神圣事业许多年了。Partner的两次使用表明实现和平需要人加入, 一起奋斗!
同义词与反义词在本篇中也起到了衔接语义的作用。同义词与反义词正确运用, 是修辞的一种手段, 也是篇章衔接的方式之一。在《要和平, 不要暴力》的语篇中也有其他的衔接的方式如同义词和反义词的使用。
同义词:Peace, election, democracy, course, path, road;for peace, want peace, desire peace, support peace, every opening, and every possibility.
反义词:peace和violence;Against violence andfor peace, desire peace and oppose peace, the path of peace and the path of war;
局部与整体词是表示个体和整体的“内包”关系, 是一种实体的“内包”。这种衔接方式在《要和平, 不要暴力!》的倒数第二段, 作为一种衔接方式出现, 如:the Israeli people;To the Jewish people around the world, themany people in the Arab world, the entire world
总结
本文以系统功能语法中的及物性理论为根据对政治演讲这一体裁进行话语分析, 找出了与这一语篇体裁相适应的语言表现形式所体现出的微观特征 (从及物性, 情态化, 语篇的词汇衔接三个方面) 。
通过以伊扎克·拉宾的《要和平, 不要暴力!》的英语演讲稿为语料, 对语篇中的及物性、情态动词、语篇衔接中的词汇衔接进行分析, 我们发现物质过程是使用最多的及物类型其次是关系过程;限定性的中量值的情态动词will的使用频率最高, 来表达一种概率即否定和肯定中间区域的一种可能性, 用高量值的限定性情态动词must来说明在现实生活中, 需承担的一种义务;重复是《要和平, 不要暴力!》的英语政治演讲稿的语篇衔接的最主要的词汇衔接方式。
英语政治演讲稿的特点, 演讲目的, 及特定的听众决定了任何英语政治演讲稿都有其共同的语言特点, 伊扎克·拉宾的《要和平, 不要暴力!》也不例外。伊扎克·拉宾的《要和平, 不要暴力!》演讲稿中表现的语言特征 (及物性、情态化、语篇衔接) 在某种程度上就折射出了所有英语政治演讲稿的特点, 如在英语政治演讲中有较多用高量值的情态词来表达义务的现象。
摘要：本文以系统功能语法中的及物性理论, 情态化, 词汇衔接为根据, 并以以色列总理伊扎克·拉宾的《要和平, 不要暴力!》这篇英文政治演讲稿为语料对政治演讲这一体裁进行话语分析, 找出了与这一语篇体裁相适应的语言表现形式所体现出的微观特征。
关键词：及物性,情态化,词汇衔接,语篇分析,政治演讲
参考文献
[1]《大学体验英语》项目组编:《大学体验英语综合教程3》 (第二版) , 高等教育出版社。
[2]胡瑾、曾蕾:《国际学术交流英语演讲稿语篇模式分析》, 外语教学与研究出版社, 2009年。
[3]胡壮麟、李永生、张德禄、李战子:《系统功能语言学概论》, 北京大学出版社, 2005。
[4]胡壮麟、朱永生、张德禄:《系统功能语法概论》1997年。
[5]李元授、邹昆山:《演讲学》, 华中科技大学出版社, 2003年。
[6]邵守义:《演讲学》, 东北师范大学出版社, 1991。
[7]王立非、李平:《全球化中的英语演讲:挑战与创新》——首届全国英语演讲教学与研究学术研讨会论文集, 外语教学与研究出版社, 2009.。
Over the past 30 years since the beginning of reforms and opening up, remarkable achievements have been made in the field of opera and musical production in China. However, there do remain some issues that can only be handled by furthering reform policies.
First of all, great productions should always be targeted at the market of a country like China with its particular situation and conditions, and should be conducted very, very cautiously so as to create small- and medium-sized operas and musicals with less investment but higher artistic quality while in the meantime keeping on searching for various market-oriented producing modes.
Secondly, in the present age of multiple opera concepts and styles, the mainstream productions should be as such: the script writing with a complex and vivid plot; the music composition with focus on tonality and with cantabile melody and voice as the main means of expression which can be actively assisted by the dramatic expression of the orchestra, making the main part of the singing easily acceptable to the audience；and the majority of singers with their eyes on the market and the audience, taking the theatric nature and appeal of an opera as the major starting point from where the artists should be able to draw the audience to the theatre by creating exquisite plays that can be enjoyed by every single spectator.
Thirdly, the popularity, entertaining nature and urban culture of a musical should be studied with great attention, while investigation should also be undertaken to find out the real interest of ordinary people and the regularities of musical production and marketing. We should also learn from the mature experience of Western musical productions and make the best use of our traditional culture as well, trying our best to integrate all relevant elements such as scripts, music and other artistic means so as to create something that would ″look beautiful, sound great and be enjoyed by all″.
Fourthly, composers and playwrights should have the sense of high morality and quality and should be free from any unhealthy ways of creation such as rashness, superficiality, extravagance and exaggeration, and should fight against such mean behaviours as acting blindly or eagerly for quick success, ignoring the reality, fabricating totally groundlessly, keeping no promises or failing to perform one＇s duty.
Fifthly, more opera and musical producers, managers and business professionals should be trained, as they are the must when Chinese operas and musicals are going to be marketized or to be enjoyed by the audience. Luckily, such metropolises as Shanghai and Beijing have already seen talents of this kind who have had enough experience and lessons as well from their past careers in organising commercial performances of operas and musicals, and who will surely encourage more successors to follow suit.
I believe that both operas and musicals should have great market and great audience in China. As long as playwrights and composers observe the artistic and market rules, work hard to improve their own ability and creativity, and search for more ways of development in the face of the opportunities and challenges, it is then for sure that opera and musical production in China will definitely be anticipating a brighter future in this new century!
The Future Belongs to the Children：Written on the
Occasion of the 25th Anniversary of the Establishment
of the Children and Young Women＇s Choir of China
National Symphony Orchestra
December 21st, 2008. It was the coldest day in Beijing since the winter came. However, the Forbidden City Concert Hall still saw so many people coming to the concert in celebration of the 25th anniversary of the world famous Children and Young Women＇s Choir of the China National Symphony Orchestra.
A big audience filled the concert hall. They came to share the happiness of the children and the entire concert show was so impressive that, to a spectator like me who has enjoyed their shows for several times, each image of their wonderful performance would remain in my mind, so unforgettable and so striking.
The choir was founded in 1983 by Prof. Yang Hongnian, music educator at the Central Conservatory of Music. He and his family have devoted so much to the development of the choir. The past 25 years saw its growth from the birth to today＇s fruitful achievements, with both joys and tears, but always persistent in pursuing their dream.
Shortly before the concert started, Li Lanqing, former Chinese Vice-Premier, sent his message for the choir： ″Developing the choral art to raise the general quality of the youth and enrich the cultural life of the society.″ This is not only an encouragement, but also a real portrait of the choir itself. Yang＇s wife, Prof. Tang Chongqing, the choir＇s artistic director, also a musician, unveiled some untold stories about the choir to the audience at the concert hall. Over the past 25 years, the choir has brought music and love to almost every corner of the world. As early as in 1987, the choir participated in the 3rd International Children＇s Choir Festival in Washington D.C. where they received the Diploma of Highest Appreciation with signature of the former US President Ronald Reagan. This marks the beginning of their world tours of singing as little ambassadors of peace, friendship and love. The choir has given nearly 600 shows for the past twenty years in such countries as Hungary, Austria, Japan, Singapore, Monaco, Italy, Sweden, Russia, Germany, Korea and Canada, as well as the region of Taiwan where they were praised as ″the common pride of the Chinese people on both sides of the Taiwan Strait″. The choir has so far won eight prizes at international contests, including four great prizes at the 44th International Polyphonic Contest ″Guido d＇Arezzo″ in Italy in 1996, the only Special Prize at the Moscow Young Talents Music Festival in honouring the 200th Birthday of Alexander Pushkin and the First Prize ″Golden Tuning Fork″ at the First International Chorus TV Contest in Russia in 1999. Moreover, they visited Monaco and Moscow together with the Chinese delegation for bidding for the 2008 Summer Olympic Games, and in particular, 66 members of the choir sang the Olympic Hymn a cappella at the Opening Ceremony of the 29th Summer Olympiad in Beijing on August 8, 2008, winning great attention from all over the world.
Apart from international chorus festival and concert shows, the choir has also attended numerous charity performances for the Project Hope, the SOS Orphans＇ Village and foreign elderly houses as well as reform centres. These regularly held charity concerts fulfilled the very objective of the choir for ″love and contribution″. The young singers of the group enjoy not only the joy of the music, but also the charms of the music. One member said that ″the choir helps me feel the happiness and sentiment that can never be described in words, and makes me touched in the cleanest and also the most sensitive heart, and this state of being touched helps me understand that I can have something that I believe in, something from the bottom of my heart rather than a particular person or deity or any doctrine or argument.″ The choir is thus filled with love and care just as the teachers love the children and vice versus.
宁静的早晨。
Sing a long song with my toddlers in the car.
与我的小宝贝在车里唱一首悠长的.歌。
Sunset and a beer with my wife.
夕阳，啤酒，爱人。
Runner’s high on a long run.
长跑后的酣畅淋漓。
Cuddling up and watching a DVD with the wife and kids.
蜷在沙发上，与妻子孩子一起看碟。
Walking outside with my son after it rains.
和我的儿子在雨中散步。
My “life” talks with my eldest daughter in the car.
在车里与我的大女儿谈论我的“人生”。
Writing a post for 50,000 people, in my pajamas.
穿着睡裤，写一篇文章，读者50, 000人。
Feeling sick and lying in bed all day without having to call my boss.
感觉不舒服，躺在床上一整天，不用给老板打电话。
Showing my 2-year-old the clear starry sky.
带我那两岁的孩子看布满星星的夜空。
Cheering my kids on in their soccer games.
为孩子们的足球赛加油喝彩。
Time alone with a good book.
独自一人，读一本好书。
Freshly brewed coffee.
喝一杯煮好的咖啡，精神饱满。
My hot veggie soup on a cold day.
寒冷冬日的一碗热蔬菜汤。
Writing before the sun rises.
在太阳升起前写作。
Fresh, cold berries.
新鲜，冰镇的浆果。
A long conversation with a friend.
和好友的一次促膝长谈。
Succumbing to a mid-afternoon nap.
午后禁不住打个小盹。
Playing kickball in the yard with my kids.
和我的孩子在花园里踢球。
The feeling of satisfaction after a workout.
经历考验后的满足感。
Waking up to a clean, uncluttered living room.
醒来发现躺在整洁的卧室里。
Laughing at my 4-year-old son’s wacky sense of humor.
对我四岁儿子独特的幽默感哈哈大笑。
Screaming my head off when my son scores a goal.
为我儿子的进球得分尖叫。
Collapsing after finishing a marathon, exhausted but in love with life.
在跑完马拉松后瘫倒在地，精疲力竭但挚爱着生活。
Spending time with my mom and sisters on a Saturday afternoon, baking sweets.
周六的午后与母亲和姐妹一起度过，烘培甜点。
Letting a warm chocolate chip cookie melt in my mouth with my eyes closed.
闭上眼睛，享受软软的巧克力曲奇在口中融化的感觉。
A long hot shower.
洗一个热水澡。
Walking with the sand between my toes as the sun goes down.
踩在沙滩上，感受沙子在脚趾间的触感，欣赏落日。
Listening to the sound of waves lapping a white sand beach.
听着海浪拍打白色沙滩的声音。
A hug when I need it.
在我需要时,给我一个拥抱。
Dew on the grass in the morning.
数字证书是一种数据文件，用来确定人们的身份和Internet上的电子资产。数字证书可以实现安全而加密的联机通信，并经常用来保护联机事务处理。
定义
随着电子交易的盛行，越来越需要第三方以数字证书的形式进行认证和授权。数字证书由被称为认证机构的可信任的第三方进行签发。认证机构对证书持有者的身份进行确认，并在证书上“签字”，来证明书该证书未曾被伪造或改变。
当某证书被认证机构进行数字化签名后，该证书的持有者就将其作为电子通行证来证明他的身份。持有者可以向要求安全访问的站点、网络或个人出示证书。
证书中的识别信息包括持有者的姓名、电子邮件地址、认机构的名称、序列号，以及证书的生效日期和失效日期。当用户的身份由认证机构确认后，证书就使用持有者的公钥来保护数据。
Web服务器也可以用使用公钥的证书来向用户的浏览器确认站点的真实性。当用户向某一个Web服务器发送机密信息，例如联机事务处理所需要的信用卡号，浏览器就会从服务器的数字证书中取出公钥来确认该服务器的身份。
公钥加密
公钥是公钥加密所使用的一对密钥中的一个，是数字认证的基础。
公钥加密利用一对公钥和私钥来进行加密和解密。这两种密钥都有数值，将该数值用于某种算法中，可将信息置乱，并只有拥有相应解密密钥的用户才能看懂信息。
一个人的公钥被其他人用来对只发给那个人的信息进行加密。当他收到信息时，就使用不被别人所知的相应密钥来对数据进行解密。一个人的公钥可以被分发给其他人，而不使私钥的保密性受到破坏。
数字证书采用公钥体制，即利用一对互相匹配的密钥进行加密、解密。每个用户自己设定一把特定的仅为本人所知的私有密钥（私钥），用它进行解密和签名；同时设定一把公共密钥（公钥）并由本人公开，为一组用户所共享，用于加密和验证签名。当发送一份保密文件时，发送方使用接收方的公钥对数据加密，而接收方则使用自己的私钥解密，这样信息就可以安全无误地到达目的地了。通过数字的手段保证加密过程是一个不可逆过程，即只有用私有密钥才能解密。在公开密钥密码体制中，常用的一种是RSA体制。其数学原理是将一个大数分解成两个质数的乘积，加密和解密用的是两个不同的密钥。即使已知明文、密文和加密密钥（公开密钥），想要推导出解密密钥（私密密钥），在计算上是不可能的。按现在的计算机技术水平，要破解目前采用的1024位RSA密钥，需要上千年的计算时间。公开密钥技术解决了密钥发布的管理问题，商户可以公开其公开密钥，而保留其私有密钥。购物者可以用人人皆知的公开密钥对发送的信息进行加密，安全地传送给商户，然后由商户用自己的私有密钥进行解密。
使用数字证书的Web服务器可以利用私钥，来确保只有它能对由Internet发给它的机密信息进行解密。Web服务器的证书是由自签的CA证书来确认，这种CA证书对发证机构进行标识。包括Microsoft Internet Explorer和Netscape Navigator在内的大多数主要的Web浏览器中，都提前安装了CA证书。
当某一Web服务器向浏览器出示时，CA证书就向用户表明该服务器证书是否可以信任。如果Web服务证书的有效性得到确认，对于采用SSL技术的服务器，该证书的公钥就可用于保护信息。
SSL安全协议使用数字证书为需求私下交流的双方创造一种安全的“通道”。在大多数主要的Web浏览器和商业Web服务器上都使用了SSL技术。
Digital Certificates
Digital certificates are data files used to establish the identity of people and electroic assets on the Internet.They for secure, encrypted online communication and are often used to protect online transactions.Definition
As electronic transactions proliferate, there’s an increasing need for third-party verification and authentication in the form of digital certificates.Digital certificates are issued by a trusted third party known as a certification authority.The CA validates the identiy of a certificate holder and “signs” the certificate to attest that it hasn’t been forged or altered.When a certificate is digitally signed by a CA ,its owner can use it as an electronic passport to prove his identity.It can be presented to Web sites, networks or individuals that require secure access.Identifying information embedded in the certificate includes the holder’s name and e-mail address, the name of the CA，a serial number and any activation or expiration data for the certificate.When a user’s identity is verified by the CA, the certificate uses the holder’s public key to protect data.Public keys are also employed by certificates that a Web server uses to confirm the authenticity of a Website for a user’s browser.When a user wants to send confidential information to a Web server, such as a credit-card number for an online transaction ,the browser will access the public key in the server’s digital certificate to verify its identity.Public-Key Cryptography
NUMERICAL CONTROL
Numerical control(N/C)is a form of programmable automation in which the processing equipment is controlled by means of numbers, letters, and other symbols, The numbers, letters, and symbols are coded in an appropriate format to define a program of instructions for a particular work part or job.When the job changes, the program of instructions is changed.The capability to change the program is what makes N/C suitable for low-and medium-volume production.It is much easier to write programs than to make major alterations of the processing equipment.There are two basic types of numerically controlled machine tools：point—to—point and continuous—path(also called contouring).Point—to—point machines use unsynchronized motors, with the result that the position of the machining head Can be assured only upon completion of a movement, or while only one motor is running.Machines of this type are principally used for straight—line cuts or for drilling or boring.The N/C system consists of the following components：data input, the tape reader with the control unit, feedback devices, and the metal—cutting machine tool or other type of N/C equipment.Data input, also called “man—to—control link”, may be provided to the machine tool manually, or entirely by automatic means.Manual methods when used as the sole source of input data are restricted to a relatively small number of inputs.Examples of manually operated devices are keyboard dials, pushbuttons, switches, or thumbwheel selectors.These are located on a console near the machine.Dials ale analog devices usually connected to a syn-chro-type resolver or potentiometer.In most cases, pushbuttons, switches, and other similar types of selectors are digital input devices.Manual input requires that the operator set the controls for each operation.It is a slow and tedious process and is seldom justified except in elementary machining applications or in special cases.In practically all cases, information is automatically supplied to the control unit and the machine tool by cards, punched tapes, or by magnetic tape.Eight—channel punched paper tape is the most commonly used form of data input for conventional N/C systems.The coded instructions on the tape consist of sections of punched holes called blocks.Each block represents a machine function, a machining operation, or a combination of the two.The entire N/C program on a tape is made up of an accumulation of these successive data blocks.Programs resulting in long tapes all wound on reels like motion-picture film.Programs on relatively short tapes may be continuously repeated by joining the two ends of the tape to form a loop.Once installed, the tape is used again and again without further handling.In this case, the operator simply loads and1
unloads the parts.Punched tapes ale prepared on type writers with special tape—punching attachments or in tape punching units connected directly to a computer system.Tape production is rarely error-free.Errors may be initially caused by the part programmer, in card punching or compilation, or as a result of physical damage to the tape during handling, etc.Several trial runs are often necessary to remove all errors and produce an acceptable working tape.While the data on the tape is fed automatically, the actual programming steps ale done manually.Before the coded tape may be prepared, the programmer, often working with a planner or a process engineer, must select the appropriate N/C machine tool, determine the kind of material to be machined, calculate the speeds and feeds, and decide upon the type of tooling needed.The dimensions on the part print are closely examined to determine a suitable zero reference point from which to start the program.A program manuscript is then written which gives coded numerical instructions describing the sequence of operations that the machine tool is required to follow to cut the part to the drawing specifications.The control unit receives and stores all coded data until a complete block of information has been accumulated.It then interprets the coded instruction and directs the machine tool through the required motions.The function of the control unit may be better understood by comparing it to the action of a dial telephone, where, as each digit is dialed, it is stored.When the entire number has been dialed, the equipment becomes activated and the call is completed.Silicon photo diodes, located in the tape reader head on the control unit, detect light as it passes through the holes in the moving tape.The light beams are converted to electrical energy, which is amplified to further strengthen the signal.The signals are then sent to registers in the control unit, where actuation signals are relayed to the machine tool drives.Some photoelectric devices are capable of reading at rates up to 1000 characters per second.High reading rates are necessary to maintain continuous machine—tool motion；otherwise dwell marks may be generated by the cutter on the part during contouring operations.The reading device must be capable of reading data blocks at a rate faster than the control system can process the data.A feedback device is a safeguard used on some N/C installations to constantly compensate for errors between the commanded position and the actual location of the moving slides of the machine tool.An N/C machine equipped with this kind of a direct feedback checking device has what is known as a closed-loop system.Positioning control is accomplished by a sensor which, during the actual operation, records the position of the slides and relays this information back to the control unit.Signals thus received ale compared to input signals on the tape, and any discrepancy between them is automatically rectified.In an alternative system, called an open—loop system, the machine is positioned solely by stepping motor drives in response to commands by a controllers.There is one basic type of NC motions.Point-to-point or Positional Control In point-to-point control the machine tool elements(tools, table, etc.)are moved to programmed locations and the machining operations performed
after the motions are completed.The path or speed of movement between locations is unimportant;only the coordinates of the end points of the motions are accurately controlled.This type of control is suitable for drill presses and some boring machines, where drilling, tapping, or boring operations must be performed at various locations on the work piece.Straight-Line or Linear Control Straight-Line control systems are able to move the cutting tool parallel to one of the major axes of the machine tool at a controlled rate suitable for machining.It is normally only possible to move in one direction at a time, so angular cuts on the work piece are not possible, consequently, for milling machines, only rectangular configurations can be machined or for lathes only surfaces parallel or perpendicular to the spindle axis can be machined.This type of controlled motion is often referred to as linear control or a half-axis of control.Machines with this form of control are also capable of point-to-point control.The original N/C used the closed—loop system.Of the two systems, closed and open loop, closed loop is more accurate and, as a consequence, is generally more expensive.Initially, open—loop systems were used almost entirely for light-duty applications because of inherent power limitations previously associated with conventional electric stepping motors.Recent advances in the development of electro hydraulic stepping motors have led to increasingly heavier machine load applications.中文译文
数控技术
数控是可编程自动化技术的一种形式,通过数字、字母和其他符号来控制加工设备。数字、字母和符号用适当的格式编码为一个特定工件定义指令程序。当工件改变时,指令程序就改变。这种改变程序的能力使数控适合于中、小批量生产,写一段新程序远比对加工设备做大的改动容易得多。
数控机床有两种基本形式：点位控制和连续控制(也称为轮廓控制)。点位控制机床采用异步电动机,因此,主轴的定位只能通过完成一个运动或一个电动机的转动来实现。这种机床主要用于直线切削或钻孔、镗孔等场合。
数控系统由下列组件组成：数据输入装置,带控制单元的磁带阅读机,反馈装置和切削机床或其他形式的数控设备。
数据输人装置,也称“人机联系装置”,可用人工或全自动方法向机床提供数据。人工方法作为输人数据唯一方法时,只限于少量输入。人工输入装置有键盘,拨号盘,按钮,开关或拨轮选择开关,这些都位于机床附近的一个控制台上。拨号盘通常连到一个同步解析器或电位计的模拟装置上。在大多数情况下,按钮、开关和其他类似的旋钮是数据输入元件。人工输入需要操作者控制每个操作,这是一个既慢又单调的过程,除了简单加工场合或特殊情况,已很少使用。
几乎所有情况下,信息都是通过卡片、穿孔纸带或磁带自动提供给控制单元。在传统的数控系统中,八信道穿孔纸带是最常用的数据输入形式,纸带上的编码指令由一系列称为程序块的穿孔组成。每一个程序块代表一种加工功能、一种操作或两者的组合。纸带上的整个数控程序由这些连续数据单元连接而成。带有程序的长带子像电影胶片一样绕在盘子上,相对较短的带子上的程序可通过将纸带两端连接形成一个循环而连续不断地重复使用。带子一旦安装好,就可反复使用而无需进一步处理。此时,操作者只是简单地上、下工件。穿孔纸带是在带有特制穿孔附件的打字机或直接连到计算机上的纸带穿孔装置上做成的。纸带制造很少不出错,错误可能由编程、卡片穿孔或编码、纸带穿孔时的物理损害等形成。通常,必须要试走几次来排除错误,才能得到一个可用的工作纸带。
虽然纸带上的数据是自动进给的,但实际编程却是手工完成的,在编码纸带做好前,编程者经常要和一个计划人员或工艺工程师一起工作,选择合适的数控机床,决定加工材料,计算切削速度和进给速度,决定所需刀具类型,仔细阅读零件图上尺寸,定下合适的程序开始的零参考点,然后写出程序清单,其上记载有描述加工顺序的编码数控指令,机床按顺序加工工件到图样要求。
控制单元接受和储存编码数据,直至形成一个完整的信息程序块,然后解释数控指令,并引导机床得到所需运动。
为更好理解控制单元的作用,可将它与拨号电话进行比较,即每拨一个数字,就储存一个,当整个数字拨好后,电话就被激活,也就完成了呼叫。
装在控制单元里的纸带阅读机,通过其内的硅光二极管,检测到穿过移动纸带上的孔漏
过的光线,将光束转变成电能,并通过放大来进一步加强信号,然后将信号送到控制单元里的寄存器,由它将动作信号传到机床驱动装置。
有些光电装置能以高达每秒1000个字节的速度阅读,这对保持机床连续动作是必须的,否则,在轮廓加工时,刀具可能在工件上产生划痕。阅读装置必须要能以比控制系统处理数据更快的速度来阅读数据程序块。
反馈装置是用在一些数控设备上的安全装置,它可连续补偿控制位置与机床运动滑台的实际位置之间的误差。装有这种直接反馈检查装置的数控机床有一个闭环系统装置。位置控制通过传感器实现,在实际工作时,记录下滑台的位置,并将这些信息送回控制单元。接受到的信号与纸带输入的信号相比较,它们之间的任何偏差都可得到纠正。
在另一个称为开环的系统中,机床仅由响应控制器命令的步进电动机驱动定位,工件的精度几乎完全取决于丝杠的精度和机床结构的刚度。有几个理由可以说明步进电机是一个自动化申请的非常有用的驱动装置。对于一件事物,它被不连续直流电压脉冲驱使,是来自数传计算机和其他的自动化的非常方便的输出控制系统。当多数是索引或其他的自动化申请所必备者的时候,步进电机对运行一个精确的有角进步也是理想的。因为控制系统不需要监听就提供特定的输出指令而且期待系统适当地反应的公开-环操作造成一个回应环,步进电机是理想的。一些工业的机械手使用高抬腿运步的马乘汽车驾驶员,而且步进电机是有用的在数字受约束的工作母机中。这些申请的大部分是公开-环 ,但是雇用回应环检测受到驱策的成份位置是可能的。环的一个分析者把真实的位置与需要的位置作比较,而且不同是考虑过的错误。那然后驾驶员能发行对步进电机的电脉冲,直到错误被减少对准零位。在这个系统中,没有信息反馈到控制单元的自矫正过程。出现误动作时,控制单元继续发出电脉冲。比如,一台数控铣床的工作台突然过载,阻力矩超过电机转矩时,将没有响应信号送回到控制器。因为,步进电机对载荷变化不敏感,所以许多数控系统设计允许电机停转。然而,尽管有可能损坏机床结构或机械传动系统,也有使用带有特高转矩步进电机的其他系统,此时,电动机有足够能力来应付系统中任何偶然事故。
