lecture7

第7讲Burke定理和排队网络Eytan Modiano麻省理工学院Burke定理• M/M/1队列有一个可以使队列结合为网络过程极大简化的有趣性质，即到达率为λ的输出M/M/1队列是一个速率λ为的泊松过程 –这是定理的一部分，符合可逆性• 马尔科夫链具有如下性质 A– P[将来|现在，过去] = P[将来|现在]现在状态，将来状态和过去状态的条件概率是独立的P[将来|现在，过去] = P[将来|现在]=> P[Xn =j |Xn+1=i, Xn+2=i2,...] = P[Xn=j | Xn+1=i] = P*ijBurke定理（续）• 定态下，时间反转的状态序列也是马尔科夫链，可以简单的表示为p i P*ij = p j P ji (例如，M/M/1 (p n)λ=(p n+1)µ)• 如果P*ij = Pij，那么马尔科夫链是可逆的–正向的转移概率和逆向概率相同–如果可逆，时间反转的状态序列与正向序列在统计上是不可区分的 • 如果p i P ij=p j P ji ，链是可逆的• 所有的产生/消失过程是可逆的–必须满足细致平衡方程Burke定理的含义• 由于正向时间的到达形成一个泊松过程，逆向时间的离开也形成一个泊松过程• 因为逆向过程在统计上与正向过程相同，（正向）离开过程是泊松的• 同理，一个（正向）离开留下的状态（系统中的分组）与过去的离开无关–逆向过程中，状态与将来的到达无关队列网络• M/M/1队列的输出过程是一个与输入有相同速率λ的泊松过程• 第二个队列是M/M/1吗?独立近似(Kleinrock)• 假设各个队列之间的服务时间是独立的–不是现实的假设：分组的服务时间由它的长度决定，但是长度在分组之间是不变的• X p=沿着链路p的分组到达速率• 令λij=链路(i,j)的分组到达速率的• µij=链路(i,j)上的服务速率Kleinrock近似• 假设所有的队列都相当于独立的M/M/1队列• N = 网络中的平均分组数量, T =网络中的平均分组延迟• 近似并不适用于所有情况，但在预测的准确性不很重要的情况下很有用–相对性能，但不是实际的性能因素–例如拓扑设计慢车效应• 慢车效应引起的聚束举例–长分组在每个节点处需要长的服务–短分组赶上长分组• 与我们在道路上经历的现象相似–慢车的后面有许多赶上他的快车跟随Jackson网络• 独立的外部泊松到达• 独立的指数服务时间–相同的工作在不用的队列里有独立的服务时间• 分组的独立路由的概率到达节点j–当一个分组离开节点i，它以Pij–分组以1=−∑j P ij的概率离开系统–分组可以在网络内部循环• 节点i处的到达速率,–可以解此方整组得到各个单独的λi–节点i处的服务速率 = µiJackson网络（续）• 用户被快速处理(µ >> λ)=• 用户以概率(1-P)离开–用于以P的概率返回队列–λ== r + Pλ==> λ== r/(1-P)• 当P大的时候，每个外部到达都跟随以一个内部到达脉冲 –队列的到达不是泊松分布Jackson定理• 我们定义系统的状态为：是节点i处的用户数其中，ni• Jackson定理:• 即，在定态时节点i (n i)的状态与其他所有节点的状态无关(在给定的时间)–独立M/M/1队列–结果出人意料：每个节点的到达既不是泊松分布，也不是独立的–与Kleinrock独立近似相类似–可逆性外生的输出是独立的和泊松的整个系统的状态与过去的外生离开无关举例λ1 = ?λ2 = ?P(n1,n2) = ?。

英国文学史及作品选读课程教课设计（第7 讲）2017-2018 学年第二学期讲课时间讲课对象15-17 级各专业选修生Chapter 5 The Rise of the Novel讲课主题(John Bunyan; Daniel Defoe)1 Help the students know some information aboutJohn Bunyan.th2 Help the students know some information about the 18 century literature.教课目标3 Help the students have a good understanding ofDaniel Defoe.与要求4 Make sure the students have a better understanding Robinsonof Crusoe Hamlet1 John Bunyan2 Enlightenment3 Sentimentalism教课重、4 Daniel Defoe难点5 Robinson Crusoe主要教课Lecture; Discussion; Multi-media方法教课内容的组织与设计Detailed Teaching Points & Procedure1 John Bunyan (1628-1688)1.1 Bunyan ’ s life●John was of humble origin, a son of a tinsmith in the village of Elstow, near Bedford,where he was born. His life covered the period of the great crisis in the puritan struggle for the survival of their various versions of extreme Protestant faith ,and himself was of Baptist sympathies .He took part in the Civil War. After the Restoration of Charles II, the Puritans underwent sever persecution and he himself was imprisoned twice for hispreaching, once for twelve years. It was during his second and shorter term that hewrote Part I of his masterpiece— The Pilgrim s Progress’.●He had little schooling. The great reputation of the Pilgrim s’Progress arises from thedepth of his experience, the spaciousness of his imagination, and the courage,honesty and nobility of his personality, all of which raise the book far above its narrow sectarian basis. He was fed by a rich, but in some ways primitive culture. The main source of this was the English Bible: there is also an element of popular secularculture—romances and the allegorizing tradition of the village sermon.1.2 Bunyan ’ s works1)The Pilgri m’s Progress《天路历程》2)The Life and Death of Mr. Badman 《恶人先生的生与死》3) The Holy War《圣战》●The Pilgrim s’Progress is a prose allegory (a story in verse or prose with doublemeanings: a surface meaning and an undersurface meaning) depicting the pilgrimageof a human soul in search of salvation. It has two parts. The first part deals withChristian ’pilgrimages to the Celestial City, through which he realized his ownsalvation. The second part deals with his wife and children ’salvation through their pilgrimage.●In the book, Christian, the hero represents everyman. He flees the terrible city ofDestruction and sets off on his pilgrimage. In the course of it he passes through theSlough of Despond, the Interpreter House,’ the House Beautiful, the Valley ofHumiliation, the Valley of the Shadow, Vanity Fair, Doubting Castle, the DelectableMountains and the country of Beulah, and finally arrives at the Celestial City. On the way he meets various characters, including Mr. Worldly Wiseman, Faithful, GiantDespair, the fiend Apollyon, and many others. In the second part his wife andchildren make their pilgrimage accompanied by Mercy. They are helped and escorted by Great–Heart who destroys Giant Despair and other monsters. Eventually they,too, arrive at the Celestial City.●Though The Pilgrim s’Progress has generally been read and appreciated as religiousbook, it also gives a faithful picture of the English society in Bunyan ’ s age, added here and therewith bitter satires upon the English ruling classes.◆ In the sense of religion it is a Protestant study which highly praises the doctrine ofProtestantism —salvation. So it appeals to Christians of every name, and toMohammedans and Buddhists in precisely the same way that it appeals toChristians. As for Puritan fathers it gave them religious instruction. All classes ofmen read the story because they found in it a true personal experience told withstrength, interest, humor, in a word, with all the qualities that such a story shouldpossess.◆From the story we can see that Bunyan gives us not only a symbolic picture ofLondon at the time of the Restoration but also a comprehensive satirical pictureof the English society and the legal procedurein England in Bunyan ’ s day.●When reading the book, such questions can be asked:◆Why Christian wants to leave the terrible city of Destruction?◆Who directs him the way to Heaven?◆What is an Evangelist?◆Which part of the book is the most famous one?◆What does “Vanity Fair ” mean?◆For what reasons did Christian and Faithful arise the anger of the people at Vanity◆What kind of symbolic meaning have you got through reading the chapter?th2 The Rise of the novel in the 18 centuryth2.1The historical background of the 18 century●At home:◆With the establishment of constitutional monarchy in England, the authoritativepower fell into the hands of parliament, which leads to a speedy development ofthe English society.◆In economy, the industrial revolution force its way into England. Enclosure of land,which was legalized, swept on an unexampled scale over the whole country.Consequently, the landlord, the capitalist and the like were enriched withenormous profits, while thousands of peasants were expropriated off the land.◆In politics, there appeared two hostile parties: the liberal Whigs and Tories. Besides,there was a third party –Jacobins, the supporter of James Ⅱ, aiming to bring the◆With the development of the society, both in economy and politics, social lifewas never as it had been before.●Abroad◆The development of English capitalism was also witnessed in the rapidly increasingcolonial expansion. Victories of wars increased the lands of British Empire and itscommercial expansion is everywhere throughout the world.◆Then there came the outbreak of American Revolution in 1776, and the FrenchRevolution in 1789, which with Liberty, Equality and Fraternity as its watchwords,awoke the oppressed people as well as the poor, and inspired them to strive foran ideal society. Thus, there arose the Enlightenment both in England and in otherthlands in Western Europe in the 18 century.Enlightenment is a progressive intellectual movement, the expression of struggleof the progressive bourgeoisie against feudalism. The Enlighteners fought againstclass inequality, stagnation, prejudice and other survivals of feudalism. Theywelcome religious intolerance, fiercely attack the church power, called on thedevelopment of science and technology and freedom of politics and academicthinking, having the greatest esteem for reason which they believed, should be theonly basis of one ’ s thinking and action. The people who greatly exerted influence upon the enlightenment are John Locke, Newton (in England) Voltaire, Rousseau, Montesquieu (in France).2.2 Literature of the periodIt is difficult to summarize the literature of this age, or to group such. Generally speaking, the literature of this century may be divided into three periods according to the development of the Enlightenment from its early stage to its eventual crisis.●The first period (1700—1745)◆This period covers the first 4 decades, and it is characterized by neo-classicism andits fine expression is in poetry and then in prose— periodicals.◆The representatives are Joseph Addition, Richard Steel, and Pope.◆The poetry of this period is chiefly a literature of wit, concerned with civilization,with man in his social relationships and consequently it is critical and in somedegree moral and satirical. The major form of poetry is heroic couplet.th◆ The first two decades of the 18 c. saw that English periodicals were mushrooming.The growth of which promoted the development of English literature, esp. thenovel.◆In the field of Periodicals, Daniel Defoe edited and published the first Englishperiodical “ the Review ” in17131704. —◆A few years later there came Addition and Steel, whose masterly editorship of tattler ”and “ the Spectator ” made-knownthemaswelltwo essayists and coauthors.●The second period (1740 -1750’s’s) —the original of realistic novelThe second period refers to the year from 1740’ tos 1750’ s,which saw the earlygrowth of realistic novels. The novelists in this period are chiefly Daniel Defoe, Swift,Samuel Richardson, Henry Fielding, Tobias Smollett and their successorsin the lastdecades of the century, such as Lawrence Sterne and Oliver Goldsmith.●The third period◆The 3rd runs through the rest decades of the century, in which the decline of thegreat enlightenment brought about sentimentalism (Thomas Gray, OliverGoldsmith, Laurence Sterne, Samuel Richardson) and pre-romanticism (WilliamBlake and Robert Burns) as protests against the social reality of the day.◆Sentimentalism is a trend of thought beginning at the second half of 18 th century,during the age of Enlightenment in England. It gains its name from an Englishauthor Sterne ’“As Sentimental Journey” .It carefully depicts person ’moodsand their miserable life so as to arouse readers ’sympathy, reflecting the disdaintowards the actual world and deep sympathy to the ordinary people. The authorsusually like to use death, dark, loneliness, etc, as their subject. Their works arealways melancholy, obscure, and full of pessimism.Characteristics of Sentimentalismare: 1) Appeal to emotion, sentiment, not reason.They believe in sentiment because they think that man’ sgood heartedness orgoodness does not result in man’ sconscious activity, but is also of born. Theybelieve that influence of art lies in cultivating the man’ s emotions firs say, they want to use their works to move readers emotion’so as to let themsympathize with the hero, and at the same the time to make them feel they are inthe same boat with the hero. This basically changes the trend(tone) of theliterature. Before almost all the works, poetry, novels or essays are ironical, satiricand mood. So they emphasize on the function of sentiment. They try to givedetailed description of characters inner’ actions and sufferings so as to arousereaders’ sympathy2)Heroes. in sentimentalists’e usuallyworksarcommon people,or the oppressed. 3) Sentimentalists usually like to idealize village or thecountryside. (Tendency of returning to the past, they like to praise patriarchalismand medievalism as their idealization. This means their dissatisfaction anddiscontent with the society they lived then. 4) Sentimentalists often turn todescribe nature. Perhaps you can find that nature and death are the themes ofsome of sentimentalists.The artistic value of sentimentalism is: 1) Pave the way for romanticism (descriptionabout nature, and the strong and exaggerated expression of emotion. 2)Sympathize with the common people and criticize the rich and the system.2.3 Daniel Defoe (1661-1731)●Defoe’s life and works◆ Personal Life : A jack-at-all trades, a Writer, a Journalist and a pamphleteer. Heknew prison life.◆His works:1) Verses:Hymn to the Pillory《立枷颂》The True Boren English man 《真实英国人》2) Prose Works:The Tour through the Whole Island of Great Britain 《不列颠全岛纪游》Captain Singleton 《辛格尔顿船长》Duncan Campbell《聋哑卜人坎贝尔传》Memoirs of a Cavalier《一个骑士的回想录》Colonel Jack,《杰克上校》Moll Flanders 《摩尔·弗兰德斯》Journal of the Plague Year《大疫年日志》Robinson Crusoe●Robinson Crusoe(Discuss the questions in theSelected Readings)◆The story of Robinson Crusoe:▼Robinson Crusoe is based on the experience of Alexander Selkirk, a sailor who marooned by his captain on the Island Juan Fernandez off the coast of Chile.▼Robinson Crusoe is a mariner who takes to the sea despite parental warnings. He suffers a number of misfortunes at the hands of Barbary pirates and the elements.Finally Crusoe is shipwrecked off South America. With salvaging needful thingsfrom the ship, Crusoe manages to survive in the island and come to terms with hisown spiritual listlessness. He stays in the island 28 years, two months andnineteen days. - Aided with his enterprising behaviour, Crusoe adapts into his alienenvironment. After several lone years he sees a strange footprint in the sand-his horrified discovery leads to encounter with savages and their prisoners,one of whom manages to escape. Crusoe meets later the frightened native andchristens his Man Friday. Finally they are rescued by an English ship boundto England.▼To depict him as a hero struggling against nature and human fate, through the characterization of his hero, Defoe seemed to fill him with his indomitable willand hand and eulogize creative labor, physical or mental, an illusion to theglorification of the bourgeois creativity when it was a rising and more energeticclass in the initial struggle of his historical development. At the early stage, thehero is an individual laborer, and then became a master, until at last a colonizer.From this character, Defoe really created an image of an enterprisingEnglishman of the 18th century. While creating this hero, Defoe just had himgone through various phases of human civilization, creating a visual picture thatmanifests how human history has developed from the primitive to the feudal andththen to the capitalistic in the 18 century.◆Theme of this story:▼This story tells us the hero ’s truggle against nature and human fate with his indomitable will and hand, through which the author eulogies creative labor, bothphysical and mental, an illusion to the glorification of the bourgeois creativitywhen it was a rising and more energetic class in its initial struggle of his historicaldevelopment. From an individual laborer to a master and colonists,Crusoe seems to have gone through various phases of human civilization, creating a visual picture to manifest how man ’ s history has developed fromprimitive to the feudal, and then to the capitalistic one in the eighteenth century.▼The novel can be read in different ways. Most simply it is a story of sea adventures. Besides, it is a story as an artistic projection of colonial expansion.Furthermore, it is a song of“the dignity of labor ”. It also expresses a desire togo back to a more economic and basic life style. (P128-129)▼By depicting Ordeals at Sea the novel conveys the idea of the ambivalence ofMastery, the necessity of repentance and the importance of self-awareness.◆The image of Robinson Crusoe▼He was one of the representatives of the rising bourgeois, who had made courageous exploration for getting new land and new resources for their foreignmarkets as well as for materials and wealth. Robinson Crusoe made severaladventures, but never satisfied and content with his temporal conditions. So inhis last adventure on the sea he was cast on an uninhabited island for 28 years.He is an enterprising Englishman.▼ He is a laborer and a typical colonizer exploiter, explorer as well as a foreign trader. Before Friday’ s appearance, he did everything himselftobuild a shelter—for rain and cold, to hunt and dry raisins for his store, to make a pot, baskets andto make a canoe. From this sense, we should say Robinson is down to down alaborer, a hard-working, industrious, intelligent man with some puritan belief.After Friday’ s appearance, Robinson immediately becamemasterthe of Friday.(The first thing he taught Friday was“ master” and let Friday do everythboth of them.) From Robinson’ s activity, we can assert that in him reflects sometypical traits of primitive accumulation.▼He is vigorous, alert and resourceful while fighting with his surrounding: the natural environment and the barbaric tribes. No matter what he is his image isnot a static one but developed from a laborer and a typical enterprisingbourgeoisie to mediocre person with a narrow-minded personality.◆Writing style:Simple, straightforward. The plot is very simple and the characterization is nottotally satisfactory.◆Significance of Robinson Crusoe▼The charm of this story mainly lies in its intense reality, in the succession of thought, feelings and incidents that every reader finds true in life.▼It is an interesting picaresque novel about an 18th-century English adventurer who is a true empire-builder, a colonizer as well as a foreign trader. When he isleft alone on the uninhabited island, he is realistically depicted as a manstruggling against nature and a man who finally creates some civilization in aseemingly primitive environment through his incessant efforts and toil.▼He resembles the rising bourgeoisie at the earliest stage of development, has the courage and will to face hardships and adversities, and also has the ingenuityand determination to preserve himself and improve on his livelihood by fightingagainst nature. He is most practical and exact, always religious and at the sametime mindful of his own profit.▼In this novel, both physical and mental labour is glorified. The detailed description of the steps taken by the hero to provide for himself shelter, foot,clothing and the other simple comforts of life, are managed with great skill bythe author—not treated with exaggeration or romantic colourings but narratedin simple, straightforward style. This adds to realistic effects of the story. Herelies the permanent glamour of the book.ⅦReflection Questions and AssignmentsReflection questions1 Through Crusoe ’ s experiences on that uninhabited island, what can we draw fromit?2 You know Crusoe at last built his own kingdom (a colony) totally by his ownefforts, through whose efforts this colony, in fact, is developed from anuninhabited island into a prosperous one. Why did Defoe write so?3 Does Defoe only want to display what happened on that island after that sailorRobinson was marooned himself or does Defoe still has something in his mind inorder to establish or put something more on the image and concept ofimperialism and colonialism.4 Whatever Defoe did, the real effect of the novel did exert great impetus on thebuilding of the image and concept of imperialism and colonialism. Why?Assignments1 Read the excerpt ofGulliver ’sTravels.2 Read the excerpt ofTom JonesⅦReflection Questions and AssignmentsReflection questions1 Through Crusoe ’ s experiences on that uninhabited island, what can we draw from it?2 You know Crusoe at last built his own kingdom (a colony) totally by his ownefforts, through whose efforts this colony, in fact, is developed from anuninhabited island into a prosperous one. Why did Defoe write so?3 Does Defoe only want to display what happened on that island after that sailor作业部署Robinson was marooned himself or does Defoe still has something in his mind inorder to establish or put something more on the image and concept ofimperialism and colonialism.4 Whatever Defoe did, the real effect of the novel did exert great impetus on thebuilding of the image and concept of imperialism and colonialism. Why?Assignments1 Read the excerpt ofGulliver ’sTravels.2 Read the excerpt ofTom Jones主要参照资料备注。

第七讲 载流子的漂移和扩散（续）9月16，2001内容：1.漂移2.扩散3.传输时间阅读作业del Alamo Ch. 4，§4.2-4.4主要问题●在电场中，载流子如何移动？漂移速度主要由什么决定？●能带图如何表示一个电场的存在？●浓度梯度如何影响载流子？●平均起来，一个载流子通过漂移或扩散从半导体的一个区域移动另一个区域要花多长时间？⒈ 漂移存在电场时载流子发生移动：□ 漂移速度－电场：ε－加在电子上的电场力：q ε−－碰撞间的加速度：ceq m ε∗−－在时间ce τ获得的速度：drift cee ce q m ετυ∗=−或 drift ee υµε=− e µ电子迁移率[2/cm V s ]迁移率表明载流子响应ε的容易程度。

drift e e υµε=−drift h h υµε=−迁移率取决于掺杂水平以及是多数载流子还是少数载流子类型。

Si 在300K 时：●在低的N时：由声子散射所限制●在高的N时：由离化杂质散射所限制□ 速度饱和隐含的假定：准平衡，也就是说，散射率不太受平衡的影响。

drift drift thυευυ:=只在对高的ε：载流子从ε许多能量→光子发射显著增强→散射率1/ε:→漂移速度饱和sat υ;对Si 在300K 时，710/sat cm s υ;漂移速度与电场的关系由下式很好的表示： 1drift satµευµευ=+m 速度饱和时所要求的电场： satsat υεµ=在现代器件中速度饱和是至关重要的：如果2500/cm V s µ=，4210/sat V cm ε=（1m µ上2V ）因为µ取决于掺杂，sat ε也取决于掺杂。

□ 粒子流和电流密度粒子流#粒子通过单位的表面（与流动方向正交）每单位时间[21cm s −−]电流密度电荷通过单位的表面（与流动方向正交）每单位时间[21cm s −−]e e J qF =−e e e n dt F n dt υυ==那么e e J qn υ=− h hJ qn υ=−漂移电流（低电场）e e J q n µε=h h J q n µε=总的为：()e h J q n p εµµε=+电导率[()1cm −Ω]：()e h q n p σµµ=+电阻率[cm Ω]：()1e h q n p ρµµ=+检查符号：()1e h q n p ρµµ=+ρ强烈的依赖于掺杂经常被硅片供应商用来表明衬底的掺杂水平 -对n 型：1n e D q N ρµ; -对p 型：1p h A q N ρµ;Si 在300K 时：漂移电流（高电场）：esat esatJ qn υ= hsat hsatJ qn υ=得到更大电流的唯一方法是增加载流子浓度。