结构 Model (1)
Qt5MVC模式（一）
Qt5MVC模式（⼀）Qt5MVC模式(⼀)：概述上By Xchen 20160627MVC设计模式起源于smalltalk的⼀种与⽤户界⾯设计相关的设计模式。
作⽤：有效的分离数据和⽤户界⾯。
组成：模型model（表⽰数据）、视图view（表⽰⽤户界⾯）、控制controller（定义⽤户在界⾯上的操作）。
interView框架Qt的MVC区别：将视图与控制结合在⼀起，同时添加了代理delegate能够⾃定义数据条⽬item的显⽰与编辑⽅式。
组成：模型model（表⽰数据）、视图view（表⽰⽤户界⾯）、代理delegate（⾃定义数据条⽬item的显⽰与编辑⽅式）。
模型与视图结构：模型与数据通信，并提供接⼝视图从模型中获取数据条⽬索引代理绘制数据条⽬通信⽅式：信号&槽⼯作过程：数据改变时，模型发出信号通知视图；⽤户对界⾯操作时，视图发出信号；代理发出信号告知模型和视图编辑器⽬前的状态；模型model（表⽰数据）抽象基类QAbstractItemModel列表的抽象基类QAbstractListModel、表格的抽象基类QAbstractTableModelQDirModel类是⽂件与⽬录的存储模型QStandardItemModel类QStringListModel类视图view（表⽰⽤户界⾯）抽象基类QAbstractItemViewQListView—QListWidget\QUndoViewQTableView—QTableWidgetQTreeView—QTreeWidgetQColumnViewQHeaderView实际上：QListWidget、QTableWidget、QTreeWidget已经包含数据，是模型与视图集成的类代理delegate（⾃定义数据条⽬item的显⽰与编辑⽅式）抽象基类QAbstractItemDelegateQItemDelegate/QStyleItemDelegate类QItemDelegate 由类QSqlRelationDelegate继承实例⼀：⽂件⽬录浏览器截图：创建过程：1. 声明⼀个QDirModel对象model；2. 分别声明三个视图对象QTreeView、QTableView、QListView；3. 设置视图对象的模型为setModel(model)；4. 设置视图的选择模式setSelectionMode(QAbstractItemView::MultiSelection)；5. 信号槽的连接6. 分隔窗体的设置头⽂件：#include <QApplication>#include <QAbstractItemModel>#include <QAbstractItemView>#include <QItemSelectionModel>#include <QDirModel>#include <QTreeView>#include <QListView>#include <QTableView>#include <QSplitter>QItemSelectionModel类：⽤来设置模型的选择模式的。
结构方程模型lecture129页PPT
模型识别
SEM的产生与发展（续1）
Jöreskog（1966,1967）开发了验证性因子 分析（CFA）
Jöreskog提出卡方检验，用来比较可测变量的观测相 关结构与假定模型所隐含的相关结构，从而否定（或 暂时验证）假设模型，是SEM发展的里程碑
可测变量
潜变量与 可测变量
潜变量与 可测变量
基本假定 变量没有测量误差
潜变量无关
可测变量可以有测量误差 潜变量可以相关
SEM的产生与发展（续4）
1970年代，LISREL的诞生极大地促进了SEM 的研究与应用
1994年，创立了专门的杂志Structural Equation Modeling
SEM的产生与发展（续2）
将Wright的路径分析与Jöreskog的CFA融合 在一起，从而诞生了SEM
SEM 研究可测变量与潜变量之间的关系
以及潜变量之间的关系
路径分析 研究可测变量之间的关系
CAF 研究可测变量与潜变量之间的关系
SEM的产生与发展（续3）
路径分析 CFA SEM
所涉变量
use of confirmatory factor analysis to reduce measurement error by having multiple indicators per latent variable
the attraction of SEM's graphical modeling interface the desirability of testing models overall rather than coefficients
20世纪末，计算科学家和科学哲学家进一步发展 了线性因果关系理论与算法，使得SEM在线性因 果关系建模中的应用在理论、统计以及计算方面 都得以深化和推广
ModelTest1----参考答案-1
2009年12月大学英语四级考试答案详解Part ⅠWritingCreating a Green CampusRecently, with the idea of making and maintaining “a green earth”being the focus of the society, “green campus” has become a more and more popular concept in universities or colleges, which, undoubtedly, will bring us an ever-lasting benefit to both our campus and our society.The concept of “green campus” does not only mean a green environment but also refers to an environmental sense in people’s mind. Campus plays a crucial role in educating the young generation and the consciousness of “green campus” will definitely produce a profound effect on students’ various environmental protection activities after their graduation. What’s more, the young generation is under the burden of severe environmental pollution and there are many problems waiting for them to solve.To make “green campus” come true, firstly, it is necessary to work out effective principles for the development of sustainable and recyclable campus. Secondly, it calls for people’s awareness of the serious pollution around us and actual action to reduce the waste. Last but not least, it is necessary to strengthen the ties between campus and society, so as to ensure that “green campus” can work smoothly with the co-effort of the whole society.Part ⅡReading Comprehension (Skimming and Scanning)篇章结构核心词汇1. aid n. ①帮助，援助②助手v. 帮助，援助【用】financial aid经济援助;merit aid/ Merit-based奖学金;need-based aid助学金或经济资助;foreign aid外援，对外援助;hearing aid助听器;aids and appliances用具，设备【搭】in aid to用来帮助，起……作用;lead one’s aid (to)援助，给予帮助;in aid of作为援助……之【拓】aidance n. 协助，帮助;aidant a. 帮助的;aided a. 辅助的2. project v. ①设计②发射n. 事业，计划，工程【用】Project Hope希望工程;project manager项目经理;project plan项目规划;project budget 项目预算，工程预算【拓】projection n. 突出，发射;projecting a. 突出的3. selective a. 选择性的【用】selective analysis重点分析;selective breeding选择育种，选择性繁殖【拓】select v. 挑选，选拔a. 精选的;selection n. 选择，挑选，选集4. package n. 包裹;套装软件，程序包a. 一揽子的【用】package design包装设计;package agreement一揽子安排，一揽子方案;package holiday(旅行社安排一切的)一揽子旅游;package tour包办旅行(路线、地点、时间和费用等均作统一规定和安排的旅游);package program组装程序【拓】pack n.包装，背包v. 包装，压紧;packaged a. 袋装的;packager n. 打包机5. ranking a. 头等的;n. 等级，地位【用】ranking list排名;ranking method等级法，排序法【拓】rank n. 等级;队列;v. 排列，6. grant v. ①授予②承认;n. ①授予物②拨款【用】grant of a patent授予专利权【搭】take…for granted认为……是理所当然; Granted/Granting that即使……(也)【拓】grants n. 补助金，津贴(grant的复数)7. enrol v. 登记，入学，参军，注册【搭】enrol in选课，参加【拓】enrollment n. 登记，入伍;enrollee n. 入学者，入伍者8. eliminate v. 消除，排除【用】eliminate illiteracy扫盲;eliminate poverty消除贫困;eliminate noise 消除噪声【拓】eliminate 是指把已进入者从中排除;exclude v. 指把想进入者拒之门外9. qualify v. 使具有资格，证明……合格【用】qualifying examination资格考试，初试;qualifying competition预选赛，资格赛【搭】qualify as 取得……资格，作为……合适;qualify for有……的资格，合格【拓】qualified a. 有资格的，合格的10. excel v. 胜过，优于，擅长n. [计算机] 软件名称【搭】to excel in/at (在某方面)胜过(或超过)别人;to excel in music 擅长音乐【拓】excellent a. 极好的，卓越的;excellence n. 优秀11. submit v. 使服从，提交【用】submit oneself to discipline遵守纪律;submit registration提交登记表，提交注册【搭】submit to 服从;submit…to 将……呈交给【拓】submission n. 服从，投降试题详解1.【原题译文】随着越来越多的低收入学生追求高等教育，一些学院__。
统计建模课程复习与练习（1）剖析
统计建模课程复习与练习（1）剖析《统计建模》复习题1.统计建模的主要步骤有哪些？1明确问题 2数据收集 3数据预处理 4模型构建 5模型估计 6模型检验 7结果分析8撰写论文2.试列举至少5个常用的统计数据库？例如，中经网统计数据库。
1国家统计数据库2中国经济网数据中心3 OECD数据库4国研网数据库5国家发改委6世界银行7中国统计年鉴、WIND数据库、BvD数据库3.试列举至少4项国内广泛使用的微观数据库？并简要说明。
1．CHIP数据（中国农村和城市居民家庭收入分配）2．CHNS（中国健康与营养调查）3．CHARLS（中国健康与养老追踪调查）4．CFPS（中国家庭动态调查）5．CHFS（China Health and Fertility Survey ）中国健康与生育调查4.常见的模型估计方法有哪些？试列举之。
最小二乘（OLS）法、极大似然估计、广义矩（GMM）法、分位数回归方法、贝叶斯估计5.在完成统计模型的参数估计后，通常需要进行哪几类检验？试列举之。
定性检验，T检验，f检验，拟合优度检验，预测精度检验6.著名统计学家博克斯（George Box）说过：所有的模型都是错的，但其中有一些模型是有用的！你对这句话如何理解？模型只能是客观世界的一种近似，是现实的简单化或理想化。
有用的模型能抓住并凸显现象中与分析目的最相关的特征，能抓住问题的本质。
7.简述结构方程模型和普通回归模型的区别？结构方程模型，是一种建立、估计和检验多个变量之间的因果关系模型的方法。
模型中既包含有可观测的显变量，也可能包含无法直接观测的潜变量。
普通回归模型属于单方程模型方法，结构方程模型属于联立方程模型方法，回归分析只能处理显性变量，而结构方程模型可以发现潜在变量。
普通回归一般只有一个因变量，而且是单向的，SEM则是可单，可双，普通回归是基础，SEM是后来的发展和完善8.和普通回归模型相比，结构方程模型有哪些优点？1允许回归方程的自变量含有测量误差2可以同时处理多个因变量3.可以在一个模型中同时处理因素的测量和因素之间的结构。
第二节 第1课时 分子结构的测定和多样性 价层电子对互斥模型(学生版)
第二节分子的空间结构第1课时分子结构的测定和多样性价层电子对互斥模型一、分子结构的测定1．分子结构的确定——红外光谱法当一束红外线透过分子时，分子会吸收跟它的某些化学键的振动频率相同的红外线，再记录到图谱上呈现吸收峰。
通过和已有谱图库比对，或通过量子化学计算，可分析出分子中含有何种化学键或官能团的信息。
如乙醇的红外光谱：读谱：该有机物分子中有3种不同的化学键，分别是C—H、O—H、C—O。
2．相对分子质量的确定——质谱法用高能电子流轰击样品分子，使分子失去电子变成带正电荷的分子离子和碎片离子等粒子。
分子离子和碎片离子各自具有不同的相对质量，它们在高压电场加速后，通过狭缝进入磁场得以分离，在记录仪上呈现一系列峰，化学家对这些峰进行系统分析，便可得知样品分子的相对分子质量。
如甲苯分子的质谱图：读谱：相对分子质量＝最大质荷比，甲苯的相对分子质量为92。
1．某有机化合物由碳、氢、氧三种元素组成，其红外光谱图只有C—H、O—H、C—O的振动吸收，该有机物的相对分子质量是60，则该有机物的结构简式是()A．CH3CH2OCH3 B．CH3CH(OH)CH3 C．CH3CH2OH D．CH3COOH2．如图是有机物A的质谱图，则A的相对分子质量是()A．29 B．43 C．57 D．72二、多样的分子空间结构观察下列几种简单的分子的空间结构模型。
(1)填写下表：(2)分析上表，各种分子的空间结构与下列哪些因素有关？①原子数目②键能③键长④键角⑤孤电子对提示①③④⑤(1)所有的三原子分子都是直线形结构()(2)所有的四原子分子都是平面三角形结构()(3)五原子分子的空间结构都是正四面体()(4)正四面体形的键角均为109°28′()(5)SiCl4、SiH4、NH＋4、CH3Cl均为正四面体结构()(6)SF6分子的空间结构为正八面体形()(7)椅式C6H12比船式C6H12稳定()1．四原子分子都是平面三角形或三角锥形吗？提示：2．空间结构相同的分子，其键角完全相同吗？提示：1．下列分子结构为正四面体形的是()①P4②NH3③CCl4④CH4⑤SO2⑥CO2A．①③④⑤B．①③④⑤⑥C．①③④D．④⑤2．(1)硫化氢(H2S)分子中，两个H—S的夹角接近90°，说明H2S分子的空间结构为________。
Model Test 1(一级)
Model Test 1 (一级)Part I. Vocabulary and Grammar. (25′)Section A Multiply Choice. (0.5×30＝15′)1. Bees__________in groups in a hive, and every bee________certain work that helps the other members of the group.A lived...didB live…doingC live…doesD living…doing2. I hope you__________ your stay in Venice next week.A enjoyB are going to enjoyC would enjoyD enjoyed3. The Safe Drinking Water Act requires that manicipal tap water__________for morethan 80 contaminants.A ought to be screenedB be screenedC need be screenedD is to be screened4. _____ the hustle and bustle of the big city, he saved up for years to buy a cottage in the countryside.A. Tiring ofB.Because tired ofC.When tiring ofD.Tired of5. For the first time in her life, she ______ a sense of fulfillment.A.feltB.has feltC.to feelD.has been feeling6. It is the first time that she_____ the moral standards of the community.A. is going to questionB.has questionedC. questionsD.questioned7.It was the second time that he_____ as a counselor at a summer camp.A. workedB.had workedC.could have workedD.must have worked8. The boy listened with amazement until the instructor insisted he_____ it.A. triedB.tryC.must tryD.would try9.Evidence from a recent study suggests that injures______ most likely to occur at social gatherings right after somebody hollers,"Hey everybody, watch this!"A.should beB.beC.areD.were10. It is a legal requirement that you_____ insurance for your car.A. haveB.need to haveC.ought to haveD.must have11. You are unlikely to succeed unless you______ his advice.A.ignoreB. understandC. rememberD. follow12. Smoking in this five-star hotel is_____.A. declinedB. preventedC. prohibitedD. refused13. When will you _____this new policy?A. adoptB. adaptC. addictD. adorn14. industrial expansion was a very sound investment in present-daysociety.A reliableB successfulC strategicD large-scale15. It is apparent that new energy sources will be required to keep up the______societies of the world in the future.A civicB civilianC civilD civilized16. It seems necessary for these newcomers to have some______at this stage for their better understanding of the new subject.A principleB principalC orientationD approach17. He _______ tonight with his horrifying fishing stories.A lived on my nervesB got on my nervesC touched a raw nerveD lost his nerve18. Many American Indians______contact with ghosts, so they disposed of the bodies of dead relatives immediately.A frightenedB scared ofC dazzledD dreaded19. His formula surprised many in the scientific community because it ______ the long-held belief.A contradictedB arguedC denouncedD criticized20. If any of the runners interfere with the others during the competition, the race is automatically declared null and ______.A coaxedB uselessC emptyD void 21．Can you tell us how you_____ the earthquake?A. were survivedB. survivedC. survived inD. survived after22."Are you still homesick? Believe me, you’ll soon_____."A. get it overB. get over itC. recoverD. recover it23. The workers were on strike, _________higher pay and better working conditions.A requiringB persistingC demandingD insisting24. The American historian Schlesinger’s works are notable for their __________insight into the sociological forces that shaped American history.A sharpB deepC keenD acute25. In order to __________ an earlier mistake, little John worked harder than before.A repayB redeemC recoverD regain26. Children __________ have better memories than adults, especially in learningforeign languages.A on averageB on the averageC on an averageD averagely27. Three Days to See____ my interest in knowing more about Helen Keller.A. roseB. aroseC. arousedD. raised28. Not knowing what to reply____ such a question, we kept silent.A. /B. toC. withD. on29. I was sick_____ his way of speaking.A. withB. offC. againstD. of30. I don’t like him; he always pokes his ______into other people’s affairs.A. fingersB. handsC. noseD. FootSection B Fill in the blanks according to the requirements. Write your answerson the answer sheet. (1×10＝10′)1.hero__________ (feminine form)2.heir (feminine form)3. We all look the wise old man. (fill in the blank with an equivalent to “respect highly”)4. The policeman began to take their statements in his book. (fill in the blank with an equivalent to “write ”)5. The letter has not been signed. It is . (the antonym of “signed”)6. His lecture is so monotonous that every one in the hall soon gets . (the antonym of “patient”)Choose from the following phrasal verbs and then fill in each blank with one that fits in the proper form.make for make off make up make up for make out7.Where we ? The school office?8.They are working hard to the lost time.9.The prisoner broke out and .10.He is murmuring. I can hardly what he is saying.Part II. Reading comprehension. (共40分，每个2分)Passage 1Nowadays, a standard for measuring power has changed. These changes foretell a new standard for measuring power. No longer will a nation's political influence be based solely on the strength of its military forces. Of course, military effectiveness will remain a primary measure of power. But political influence is also closely tied to industrial competitiveness. It's often said that without its military the Soviet Union would really be a third-world nation. The new standard of power and influence that is evolving now places more emphasis on the ability of a country to compete effectively in the economic markets of the world.America must recognize this new course of events. Our success in shaping world events over the past 40 years has been the direct result of our ability to adapt technology and to take advantage of the capabilities of our people for the purpose of maintaining peace. Our industrial prowess (工业实力)over most of this period was unchallenged. It is ironic that it is just this prowess that has enabled other countries to prosper and in turn to threaten our industrial leadership.The competitiveness of America's industrial base is an issue bigger than the Department of Defense and is going to require the efforts of the major institutional forces in our society-government, industry, and education. That is not to say that the Defense Department will not be a strong force in the process because we will. But we simply cannot be, nor should we be, looked upon by others as the savior of American industry.31. Now a nation's political influence depends on _________.A. the strength of its military forcesB. its ability to compete in industryC. economic marketsD. both A and B32. The Soviet Union was not listed as a third-world nation just because of_________.A. its powerful military forcesB. its vast landC. its industrial competitivenessD.its contributions to world peace33. The author indicates that ______ is threatening American political power.A. other countriesB. the declining U.S. industrial baseC. a new standard for measuring powerD. less advanced technology34. America succeeded in shaping world events over past 40 years probably because of ___________.A. its ability to adapt technologyB. its ability to take advantage of the capabilities of its peopleC. its ability to compete in the world marketsD. both A and B35. The purpose of writing this article is __________.A. to draw the readers' attention to a new standard for measuring powerB. to demonstrate American political influence in the worldC. to emphasize that efforts must be made to strengthen the declining U.S. industrialbase.D. to show American industrial prowessPassage 2Many people believe the glare from snow causes snow-blindness. Yet, dark glasses or not, they find themselves suffering from headaches and watering eyes, and even snow-blindness, when exposed to several hours of "snow light".The United States Army has now determined that glare from snow does not cause snow-blindness in troops in a snow-covered country. Rather, a man's eyes frequently find nothing to focus on in a broad expanse of barren snow-covered terrain. So his gaze continually shifts and jumps back and forth over the entire landscape in search of something to look at. Finding nothing, hour after hour, the eyes never stop searching and the eyeballs become sore and the eye muscles ache. Nature offsets this irritation by producing more fluid which covers the eyeball. The fluid covers the eyeball in increasing quantity until vision blurs, then is obscured, and the result is total, even though temporary, snow-blindness.Experiments led the Army to a simple method of overcoming this problem. Scouts ahead of a main body of troops are trained to shake snow from evergreen bushes, creating a dotted line as they cross completely snow-covered landscape; Eventhe scouts themselves throw lightweight, dark colored objects ahead on which they too can focus. The men following can then see something. Their gaze is arrested. Their eyes focus on a bush and having found something to see, stop scouring the snow-blanketed landscape. By focusing their attention on one object at a time, the men can cross the snow without becoming hopelessly snow blindness or lost. In this way the problem of crossing a solid white terrain is overcome.36. To prevent headaches, watering eyes and blindness caused by the glare from snow, dark glasses are_____.A.indispensableefulC.ineffectiveD.available37. When the eyes are sore, tears are produced to ________.A.clear the visionB.remedy snow-blindnessC.ease the irritationD.loosen the muscles38. Snow-blindness may be avoided by_______.A.concentrating to the solid white terrainB.searching for something to look at in snow-covered terrainC.providing the eyes with something to focus onD.covering the eyeballs with fluid39.The scouts shake snow from evergreen bushes in order to _______.A.give the men behind something to seeB.beautify the landscapeC.warm themselves in the coldD.prevent the men behind from losing their way40. A suitable title for this passage would be _______.A.snow-blindness and how to overcome itB.nature's cure for snow-blindnessC.soldiers in the snowD.snow visionPassage 3Let children learn to judge their own work. A child learning to talk does not learn by being corrected all the time; if corrected too much, he will stop talking. He notices a thousand times a day the difference between the language he uses and the languages those around him use. Bit by bit, he makes the necessary changes to make his language like other people. In the same way, when children learn to do all the other things they learn to do without being taught-to walk, run, climb, whistle, ride a bicycle. They compare those performances with those of more skilled people, and slowly make the needed changes. But in school we never give a child a chance to find out his own mistakes for himself, let alone correct them. We do it all for him. We actas if we thought that he would never notice a mistake unless it was pointed out to him, or correct it unless he was made to. Soon he becomes dependent on the teacher. Let him do it himself. Let him work out, with the help of other children if he wants it, what this word says, what answer is to that problem, whether this is a good way of saying or doing this or not.If it is a matter of right answers, as it may be in mathematics or science, give him the answer book. Let him correct his own papers. Why should we teachers waste time on such routine work? Our job should be to help the child when he tells us that he can’t find the way to get the right answer. Let’s end this nonsense of grades, exams, marks, Let us throw them all out, and let the children learn what all educated persons must some day learn, how to measure their own understanding, how to know what they know or do not know.Let them get on with this job in the way that seems sensible to them. With our help as school teachers if they ask for it. The idea that there is a body of knowledge to be learnt at school and used for the rest of one’s life is non sense in a world as complicated and rapidly changing as ours. Anxious parents and teachers say, “But suppose they fail to learn something essential they will need to get in the world?” Don’t worry! If it is essential, they will go out into the world and le arn it.41.What does the author think is the best way for children to learn things?A.by copying what other people do.B.by making mistakes and having them corrected.C.by listening to explanations from skilled people.D.by asking a great many questions.42.What does the author think teachers do which they should not do?A.They give children correct answers.B.They point out children’s mistakes to them.C.They allow children to mark their own work.D.They encourage children to mark to copy from one another.43.The passage suggests that learning to speak and learning to ride a bicycle are___.A.not really important skills.B.more important than other skills.C.basically different from learning adult skills.D.basically the same as learning other skills.44.Exams, grades, and marks should be abolished because children’s progress should only be estimated by___.cated persons.B.the children themselves.C.teachers.D.parents.45.The author fears that children will grow up into adults while being___.A.too independent of others.B.too critical of themselves.C.incapable to think for themselves.D.incapable to use basic skills.Passage 4On Thursday afternoon Mrs. Clarke, dressed for going out, took her handbag with her money and her keys in it, pulled the door behind her to lock it and went to the over 60s Club. She always went there on Thursdays. It was a nice outing for an old woman who lived alone.At six o'clock she came home, let herself in and at once smelt cigarette smoke. Cigarette smoke in her house? How? How? Had someone got in? She checked the back door and the windows. All were locked or fastened as usual. There was no sign of forced entry.Over a cup of tea she wondered whether someone might have a key that fitted her front door-"a master key"perhaps. So she stayed at home the following Thursday. Nothing happened. Was anyone watching her movements? On the Thursday after that she went out at her usual time, dressed as usual, but she didn't go to the club. Instead she took a short cut home again, letting herself in through her garden and the back door. She settled down to wait.It was just after four o'clock when the front door bell rang. Mrs. Clarke was making a cup of tea at the time. The bell rang again, and then she heard her letter-box being pushed open. With the kettle of boiling water in her hand, she moved quietly towards the front door. A long piece of wire appeared through the letter-box, and then a hand. The wire turned and caught around the knob on the door-lock. Mrs. Clarke raised the kettle and poured the water over the hand. There was a shout outside, and the skin seemed to drop off the fingers like a glove. The wire fell to the floor, the hand was pulled back, and Mrs. Clarke heard the sound of running feet.46. Mrs. Clarke looked forward to Thursday because_______.A. she worked at a club on the dayB. she visited a club on ThursdayC. she said visitors on ThursdaysD.a special visitor came on Thursday47. If someone had made a forced entry,_______.A. he or she would have needed a master keyB. he or she was still in the houseC. things would have been thrown aboutD.Mrs.Clarke would have found a broken door or window48. On the third Thursday Mrs. Clarke went out_______.A.in an attempt to trick the thiefB.to see if the thief was hanging about outsideC.because she didn't want to miss the club againD.to the club but then changed her mind49. The lock on the front door was one which_______.A.could he opened from inside without a keyB. needed a piece of wire to open itC.couldn't be opened without a keyed a knob instead of a key50. The wire felt to the floor_______.A.because Mrs.Clarke refused to open the doorB.when the man's glove dropped offC.because the man just wanted to get awayD.because it was too hot to holdPart III. Fill in each blank with a word. Write your answers on the answer sheet.（1×15＝15′）Most Americans think that ice cream is as American (1) baseball (2) apple pie. (3) ice cream was known long (4) America was discovered.The Roman emperor Nero may have made a kind (5) ice cream. He hired hundreds (6) men to bring snow and ice (7) the mountains. He used it to make cold drinks. Traveller Marco Polo brought back recipes (8) chilled(9) frozen milk (10) China.Hundreds (11) years later, ice cream reached England. It is said (12) King Charles I enjoyed that treat very much. There is a story (13) bribed his cook to keep the recipe (14) ice cream a royal secret.Today ice cream is known (15) the world. Americans alone eat more than two billion quarts a year.Part IV. Translation. Write your answers on the answer sheet. ( 2×6＋3=15′)1.那是我第一次与雇主发生这么大的纠葛(trouble)。
灰色系统GM(1,1)模型
ε=
1 ε 0 ( k ), ∑ n k =1
2 S2 =
1 ε 0 (k ) − ε ∑ n k =1
(
)
分别为残差的均值、方差。
s2 1. C = 称为均方差比值，对于给定 s1
的 C0 > 0 ,当 C < C0 时，称模型为均方差比合 格模型。 p = p ( ε 0 ( k ) − ε < 0.6745S1 ) 称为小误差概率，对 2. 于给定的 p0 > 0 ,当 p > p0 差概率合格模型。 ，称模型为小误
则 ε0 (k ) △ 1.对于 k ≤ n ，称，k = x ( k ) 为 k 点的模拟相
0
对误差，称 为平均相对误差。 2.称1− ∆ 为平均相对精度，1 − ∆ k 为 k点的模拟 精度。 3.给定α ，当 ∆ < α 且∆ n < α 成立时，称模型 为残差合格模型
,均方差比值为一
计算小误差概率： 0.6745S1 = 4116.80
ε (1) − ε = 18.75, ε ( 3) − ε = 55.25, ε ( 2 ) − ε = 24.75 ε ( 4 ) − ε = 11.75
所以p = p ( ε ( k ) − ε < 0.6745S1 ) = 1>0.95,小误差概率 为一级，故可用
精度检验等级参照表
指标精度 等级
相对误 差α 0.01 0.05 0.10 0.20
关联度
ε0
0.90 0.80 0.70 0.60
均方差比 小误差概 值 C 率 p
0
0
一级 二级 三级 四级
平稳时间序列分析-ARMA模型(1)
即自相关函数中包含了这种所有的“间接”相关。
与之相反，Xt与Xt-k间的偏自相关函数 (partial autocorrelation，简记为PACF)则是消除 了中间变量Xt-1，…，Xt-k+1 带来的间接相关后的 直接相关性，它是在已知序列值Xt-1，…，Xt-k+1 的条件下，Xt与Xt-k间关系的度量。
(3)xt xt1 0.5xt2 t
(4)xt xt1 0.5xt1 t
例3.1平稳序列时序图
(1)xt 0.8xt1 t
(3)xt xt1 0.5xt2 t
例3.1非平稳序列时序图
(2)xt 1.1xt1 t
(4)xt xt1 0.5xt1 t
从时序图上可以看出，（1）（3）模型平稳， （2）（4）模型非平稳。
0
2 X
2
12
在稳定条件下，该方差是一非负的常数，从而有
||<1。
而AR(1)的算子多项式方程：
(z) 1z 0
的根为z=1/ AR(1)稳定，即 || <1，意味着特征根大于1。
2、AR(2)模型平稳条件
xt 1xt1 2 xt2 t
特征根为
1 1
12 42
2
2 1
12 42
xt xt1 t
特征根为 ，平稳条件 1
平稳域为 ; 1
AR(1)模型的平稳性条件也可以如下讨论：
对1阶自回归模型AR(1)
X t X t1 t
方程两边平方再求数学期望，得到Xt的方差：
E(
X
2 t
)
2
E(
X
2 t 1