Lecture05 第1章 1.4_2014done

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Lecture 05 ADM - Cash and Receivables-1 现金及应收账款

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CASH
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Limitations of internal control
• Cost vs. Benefit – Cost of establishing procedure should not exceed expected benefit
• Human element – Fatigue, carelessness, indifference
The role of internal audit is to provide independent assurance that an organisation's risk management, governance and internal control processes are operating effectively. Internal Audit teams duty is to provide an unbiased and objective view. ... In sum, internal auditors help organisations to succeed.
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Principles of internal control (Continued) 5. Independent internal verification
➢ Checking procedures to ensure segregation of duties ➢ Monitoring by supervisors ➢ Rotation of duties ➢ Verification by internal auditor
3. Physical, mechanical and electronic controls

2014年10月自考《英语一》讲义 Unit 05_(含课文、生词表、课后练习及答案)

Unit 5 Music and LeisureA FAMOUS QUOTEWithout music, life would be a mistake.——Friedrich Nietzsche音乐是生命的支柱。

——弗里德里希·尼采Friedrich Nietzsche （1844-1900）, German-Swiss philosopher and writer, one of the most influential of modern thinkers.He wrote critical texts on religion, morality, contemporary cult philosophy and science.弗里德里希·威廉·尼采（Friedrich Wilhelm Nietzsche，1844～1900）德国-瑞士哲学家、作家，同时最有影响力的现代思想家之一。

他写的批评主题学说涉及到宗教信仰、道德品行、当代文化、哲学和科学等领Speaking ActivityMaking an AppointmentSample DialogueRead the following conversation.Pay attention to how the speakers make an appointment.Cindy:Dr.Peterson's office.How can I help you?David: I'd like to make an appointment.Would Dr.Peterson be able to see me at 9:30 tomorrow Cindy: I'm sorry, but he hasn't got any openings until 11:00, unless there's a cancellation David: Would 1:00 in the afternoon be convenient?Cindy: Yes, he's free then.May I have your name?David: Yes, it's David Lain.Cindy: Have you seen Dr.Peterson before?David: Yes, I had a physical examination last year.Cindy: Right.I've scheduled you in for 1:00 o'clock.David: Thank you.Guided PracticeDirections: Work with your partner and make up a situation in which you invite your partner dinner.You may use the following tips to help you.Are you available on …？Can we meet on …?Is…convenient for you?What about …？Yes, … is fine.Sorry, I'm afraid I can't…Text ANew Words1、universal adj.done by or involving all the people in the world or in a particular group 界的；共同的2、define v.to say or explain what the meaning of a word or phrase is 解释（词语的含义）；给定义3、melody n.a tune, especially the main tune in a piece of music written for several instru or voices 旋律；曲调；（尤指）主旋律4、beat v.to make, or cause something to make, a regular sound or movement（使）规律作响，作运动5、tune n.a series of musical notes that are sung or played in a particular order to form a piece of music 曲调；曲子6、personal adj.your own; not belonging to or connected with anyone else 个人的；私人的7、definition n.what an idea, etc.means 定义8、vary v.to be different from each other in size, shape, etc.（大小、形状等）相异，不同，有9、bucket n.an open container with a handle, used for carrying or holding liquids, sand, et （有提梁的）桶10、shudder v.to shake because you are cold or frightened, or because of a strong feeling 发打颤，战栗11、variety n.several different sorts of the same thing 不同种类，多种式样12、genre n.a particular type or style of literature, art, film or music that you can recog because of its special features 体裁，类型13、perspective n.the ability to think about problems and decisions in a reasonable way wit exaggerating their importance 客观判断力；权衡轻重的能力14、icebreaker n.a thing that you do or say, like game or a joke to make people feel less nervous when whey first meet 消除隔阂的行动，活跃气氛的话15、option n.something that you can choose to have or do; the freedom to choose what you do 择的事物；选择16、evoke v.to bring a feeling, a memory or an image into your mind 引起，唤起（感情、记忆或象）17、soothe v.to make somebody who is anxious, upset, etc.feel calmer 安慰；抚慰；劝慰18、unwind v.to stop worrying or thinking about problems and start to relax 放松；轻松19、comfort v.to make somebody who is worried or unhappy feel better by being kind and sympathetic towards them 安慰；抚慰；宽慰n.a person or thing that helps you when you are suffering, worried or unhappy 令人感到安慰的（或事物）20、motivate v.to make somebody want to do something, especially something that involves ha work and effort 推动…甘愿苦干；激励；激发21、pump v.（of a liquid）to flow in a particular direction as if it is being forced by a p （液体）涌出：涌流；奔流22、productive adj.doing or achieving a lot 有效益的；富有成效的23、creativity n.the ability to use your imagination to produce new ideas, make things, etc 力24、aspect n.a particular part or feature of a situation, an idea, a problem, etc.; a way i which it may be considered 方面；层面25、instrument n.an object used for producing musical sounds, for example a piano or a drum26、imagination n.the ability to create pictures in your mind; the part of your mind that d this 想象力；想象27、crave v.to have a very strong desire for something 渴望；热望28、addiction n.the condition of being addicted to something 瘾；入迷；嗜好29、cope v.to deal successfully with something difficult （成功地）对付，处理30、tension n.a situation in which people do not trust each other, or feel unfriendly towar each other, and which may cause them to attack each other 紧张局势（或关系、状况）31、inspiration n.the process that takes place when somebody sees or hears something that c them to have exciting new ideas or makes them want to create something, especially in art, musi literature 灵感32、unlock v.to undo the lock of a door, window, etc., using a key（用钥匙）开…的锁Phrases and Expressions1、relate to to be able to understand and have sympathy with somebody/something 产生共鸣；领了解；认同2、in hand used to say an undertaking is being dealt with 正在处理中Text APre-reading Questions1.Do you enjoy listening to music? What kind of music do you like best?2.Do you agree that music is a universal language?Music as a Universal LanguageThe importance of music in our lives cannot be defined with words.It is the air we breathe the thoughts we think.It is the melodies that beat to the tune of our hearts.It is the universa language that we can all understand and relate to, even when our personal definitions vary.①Mu is a very valuable tool throughout the world.I am not a musician.I couldn't carry a tune in a big old bucket, yet I still sing along wit favorite song.②I shudder at the thought of life without music.Music is a very important part o world and without it I don't know how I would have come as far as I have.③Music is variety.Because there are many different styles and genres of music, there is some for everyone.Although we may not always like every type of music on the market, the variety mak music universal.Music is the voice we long for when we can't find words to speak.Many people will agree tha there are songs that were written just for them.④Songs can sometimes say things better than we could have said them .They can express our emotions though we didn't really know we felt that way.Music can put things into perspective.⑤Music is a great icebreaker.There are a lot of topics to be discussed when it comes to musi If you are talking about music, dead silence isn't an option.Playing music in the background at parties will help calm your guests.Music sets the mood and makes things happier.Music speaks to our emotions.It evokes memories.It can remind us of happy times.It can help relate to experiences.It can bring a smile to our face or tears to our eyes.Music is a link to soul.Music soothes, and relaxes us.Music is a great way to unwind.It helps us feel better when w blue.⑦It comforts us when we are lonely, yet it makes us realize that we aren't alone.Music motivates us.Listening to music can prepare us for many possibilities.It gets our blo pumping and points us in the right direction.Music can make us feel more productive.It prepares for the task in hand.Music gives us a means of creativity.There are many aspects to music, such as playing an instrument, writing the words, or even dancing.If we use music to help us create, our imaginati has no limits.I need music like the flowers need rain.I crave it like a child craves candy.It is a health addiction and a pleasant way of coping with the many tensions of life.Music is as important to breathing and food.It is my escape, my comfort, and my inspiration.Music is the key that unlock soul.Key Sentences1、It is the universal language that we can all understand and relate to, even when our per definitions vary.即使我们个人对音乐的定义各不相同，它也是我们都能理解和产生共鸣的通用语言。

Lecture05多元时间序列分析方法

第五章多元时间序列分析方法
第一节协整检验第二节误差修正模型第三节向量自回归模型(VAR) 第四节格兰杰因果检验
协整检验
第一节协整检验
一、协整概念与定义
在经济运行中，虽然一组时间序列变量都是随机游走，但它们的某个线性组合却可能是平稳的，在这种情况下，我们称这两个变量是平稳的，既存在协整关系。
其基本思想是，如果两个(或两个以上)的时间序列变量是非平稳的，但它们的某种线性组合却表现出乎稳性，则这些变量之间存在长期稳定关系，即协整关系。根据以上叙述，我们将给出协整这一重要概念。一般而言，协整是指两个或两个以上同阶单整的非平稳时间序列的组合是平稳时间序列，则这些变量之间的关系的就是协整的。
向量自回归模型(VAR)
三、向量自回归模型(VAR)的估计
应用Eviews软件，创建VAR对应选择 Quick/Estimate VAR，或选择Objects/new object/VAR，也可以在命令窗口直接键入VAR。
向量自回归模型(VAR)
四、脉冲响应函数与预测方差分解
从结构性上看，VAR模型的F检验不能揭示某个给定变量的变化对系统内其它变量产生的影响是正向还是负向的，以及这个变量的变化在系统内会产生多长时间的影响。然而，这些信息可以通过考察VAR模型中的脉冲响应（Impulse Response )和方差分解（Variance Decompositions）得到。
协整检验
（一）E-G两步法
E-G两步法，具体分为以下两个步骤：
第一步是应用OLS估计下列方程
yt a xt ut
这一模型称为协整回归，称为协整参数，并得到相应的残差序列：
第二步检验序uˆt列的yt 平(a稳ˆ 性ˆx。t )

2014年10月自考《英语一》讲义 Unit 05_(含课文、生词表、课后练习及答案)

Unit 5 Music and LeisureA FAMOUS QUOTEWithout music, life would be a mistake.——Friedrich Nietzsche音乐是生命的支柱。

简明英语测试教程Lecture 05

N) technology O) victims
精品PPT
4.3 Matching
4.4 Information transfer
4.5 Ordering tasks
4.6 Fill-in and Cloze
4.6.1 Fill-in 4.6.2 Gap-filling
(1. to 2 affect/influence 3. Others 4. each/them
From Integrated course Book 2, Unit 1)
精品PPT
Today, I went to the ________ and bought some milk and eggs. I knew it was going to rain, but I forgot to take my ________, and ended up getting wet on the way ________.
……
A) acting B) assuming C) comprehensive D) cooperative E) entire F)
especially G) forward H) images I) information J) offers K) projects
L) respectively M) role
2 ___
C. because it was one he and Richard had learnt at school 3 ___
D. Peter looked outside
4 ___
E. He recognized the tune
5 ___
F. and it seemed deserted

lecture05

EE 338L CMOS Analog Integrated Circuit DesignLecture 5, Single-Stage Amplifiers (2)Calculations of Small Signal Input and Output ImpedancesHow to calculate input and output impedances (or admittances) of an amplifier? In the following sections, we assume that the amplifier is a voltage amplifier, whose input and output are both voltages. But we can easily extend the principles to any other types of amplifiers, such as current amplifiers (input and output are both currents), transimpedance amplifiers (input: current, output: voltage), and transconductance amplifiers (input: voltage, output: current).1. Input impedanceMethod A:i) Apply tst v at the input (* seenote below), draw the smallsignal diagram.ii) Calculate )(tst tst v f i =.iii) The input impedance isgiven by tsttst in i vz =, and the inputadmittance is tsttst in v iy =.Method B:i) Apply tst i at the input, draw thesmall signal diagram. ii) Calculate )(tst tst i f v =.iii) The input impedance isgiven by tsttst in i vz =, and the inputadmittance is tsttst in v iy =.* Note: If the amplifier requires an output termination, we should terminate the output accordingly. The load condition may affect the input impedance.iv tst2. Output impedanceMethod A:i) Set 0=in v , or if the input is a signal current, set 0=in i (** see note below).ii) Apply tst v at the output, draw the small signal diagram. iii) Calculate )(tst tst v f i =.iv) The output impedance is given by tsttst out i vz =, and the output admittanceis tsttst out v iy =.Method B:i) Set 0=in v , or if the input is a current, set 0=in i (** see note below).ii) Apply tst i at the output, draw the small signal diagram.iii) Calculate )(tst tst i f v =.iv) The output impedance is given by tsttst out i vz =, and the output admittanceis tsttst out v iy =** Note: If the amplifier requires some input termination, we should terminate the input accordingly. The input termination may affect the output impedance.Example : Calculate the output impedance of the following circuit, assuming both M1 and M2 work in saturation region. The small signal parameters of M1 and M2 are shown in the following table.Transconductance Bulk transconductance Drain-sourceconductanceM1 g m1 g mb1 g ds1 M2 g m2 g mb2 g ds2Note: As g mb is not 0, we take bulk (or body) effect into consideration. As g ds is not 0, we also consider channel length modulation effect.v tsttstSolution:(1) Set v in =0, and draw the small signal digram.(2) Apply i tst at the output. The small signal diagram is shown in Fig. 1.v intstFig. 1.Note that v gs1=0, and v bs1=0, thus the two voltage controlled current sources inFig. 1 are actually 0 (see Fig. 1). We redraw Fig. 1 as Fig. 2.tstFig. 2(3) For Fig. 2, according to KCL,tst i i i i i =++=2322211Thusv V1112ds tst ds s g i g i v ==Note that, v g2=v b2=0, thus22222222221)()(s m s m s g m gs m v g v g v v g v g i −=−=−== (3)22222222223)()(s mb s mb s b mb bs mb v g v g v v g v g i −=−=−== (4)and)()(222222222s tst ds s d ds ds ds v v g v v g v g i −=−== (5)Eq. (3)+Eq. (4)+Eq. (5), and combine with Eq. (1), we arrive at,tsts mb ds m tst ds s mb s tst ds s m i v g g g v g v g v v g v g i i i =++−=−−+−=++22222222222232221)()( (6)From Eq. (6) we can write,222221ds tsts ds mb m tst g i v g g g v +⎟⎟⎠⎞⎜⎜⎝⎛++=Substitute Eq. (2) into Eq. (7),tst ds ds ds ds mb m ds tst ds tst ds mb m tst i g g g g g g g i g i g g g v ⎟⎟⎠⎞⎜⎜⎝⎛+++=+⎟⎟⎠⎞⎜⎜⎝⎛++=21212221222111 (8) Thus,21212211ds ds ds ds mb m tst tst out g g g g g g i v r +++==(9a)Note that 111ds ds g r =, 221ds ds g r =, and m mb g g η=, Eq. (9a) can be re-written as, 21222122221212212122]1)1([]1)[()1()(ds ds ds m ds ds ds mb m ds ds ds ds m ds ds ds ds mb m tst tstout r r r g r r r g g r r r r g r r r r g g i v r +++=+++=+++=+++==ηη (9b)v V 122122212122)()(ds ds ds mb m ds ds ds ds mb m out r A r r g g r r r r g g r =+≈+++=where2222)(ds mb m r g g A +=Example : 1) Assuming 0=λ, and 0=γ, what is the input impedance of the amplifier? 2) if 0≠λ, and 0≠γ, please repeat 1). Note that V B is a DC bias voltage.Solution:1) As 0=λ, and 0=γ, we have 0=ds g and 0=mb g . Draw the small signal diagram, and apply v tst at the input.g =0iFig. 1From Fig. 1, we have,tst m tst m s g m gs m d tst v g v g v v g v g i i =−−=−−=−=−=)0()(Thus,V DD v inm tst tst in g i v r 1==2) As 0≠λ, and 0≠γ, we have 0≠ds g and 0≠mb g .Draw the small signal diagram as Fig. 2, and apply v tst at the input. According to KCL,)(232221i i i i tst ++−=(1)gs =-g m v tsti 23=g mb v bs =-g i 22=g ds v dsFig. 2From Fig. 2, we can write tst m tst m s g m gs m v g v g v v g v g i −=−=−==)0()(21 (2))()(22tst out ds s d ds ds ds v v g v v g v g i −=−== (3) tst mb tst mb s b mb bs mb v g v g v v g v g i −=−=−==)0()(23 (4)D tst out R i v =(5)Substitute Eqs. (2)-(5) into Eq. (1), we havetst D ds tst ds mb m out ds tst ds mb m tst i R g v g g g v g v g g g i −++=−++=)()( (6a) Simplify Eq. (6) as tst ds mb m tst D ds v g g g i R g )()1(++=+(6b)Thusdsmb m D ds tst tstin g g g R g i v r +++==1Source Followers (Common Drain Amplifiers)(b)Input terminal: gate; output terminal: source.Note that, not all process technologies allow the source and the bulk of NMOS transistors to be connected together. The above schematics only show the concept.Large signal behavior Input/Output Voltage(V)Vout(d)VinVout(b)Input Voltage(V)(V DD=3.3V, W/L=8(6/0.9), R S=5K, I B=120u)When V in<V T, M1 is off, and Vout is 0.When V in>V T, M1 turns on in saturation. As V in increases further, V out follows Vin with a difference of V GS.When V in increases to a certain voltage (exceeding V DD), M1 enters triode region, the output voltage flattens out and clips at V DD.Small signal analysisWe only perform small signal analysis for the schematic above. The small signal diagram is shown in the right side.Note that, 2322211i i i i ++=(1)and SoutR v i =1 (2) )()(21out in m s g m gs m v v g v v g v g i −=−== (3) out ds out ds ds ds v g v g v g i −=−==)0(22(4)out mb out mb s b mb bs mb v g v g v v g v g i −=−=−==)0()(23 (5) Substitute Eqs. (2)-(5) into Eq. (1), and after some simplification, we obtain, out ds mb m in m Soutv g g g v g R v )(++−= (6)ThusSds mb m minout v R g g g g v v A 1+++==(7)Example . For the amplifier shown below (left side), assuming, 0≠λ, and 0≠γ.1) What is the small signal voltage gain inout v v vA =?2) What is the small signal output resistance out r ?outsSmall signal diagramFig. 1, Original schematic and small signal diagram for calculating small signalvoltage gain1) What is the small signal voltage gain inoutv v v A =? Solution:The small signal diagram is drawn in the right side in Fig. 1 above. According to KCL, we have 0232221=++i i i (1a) where )()(21out in m s g m gs m v v g v v g v g i −=−== (1b) out ds out ds s d ds ds ds v g v g v v g v g i −=−=−==)0()(22 (1c)out mb out mb s b mb bs mb v g v g v v g v g i −=−=−==)0()(23 (1d)Combine Eqs. (1a)-(1d), we have dsmb m min out g g g g v v ++= (2)2) What is the small signal output resistance out r ? Solution:Following the steps to calculate output resistance. (i) Set v in = 0.(ii) Apply v tst at the output, and draw the small signal diagram as shown below.Fig. 2, Small signal diagram for calculating output resistance(iii) According to KCL, we have0232221=+++tst i i i i (3) where tst m tst m s g m gs m v g v g v v g v g i −=−=−==)0()(21 (4a) tst ds out ds s d ds ds ds v g v g v v g v g i −=−=−==)0()(22 (4b)tst mb out mb s b mb bs mb v g v g v v g v g i −=−=−==)0()(23 (4c)Substitute Eqs. (4a)-(4c) into Eq. (3)tst ds mb m tst v g g g i i i i )()(232221++=++−= (5)(iii) Thus dsmb m tst tst out g g g i v r ++==1Example . For the amplifier shown below, assuming, 0≠λ, and 0≠γ.1) What is the small signal voltage gain inout v v vA =,2) What is the small signal output resistance out r ?V outFig. 1, Original schematic and small signal diagram for calculating small signalvoltage gain1) What is the small signal voltage gain inoutv v v A =? Solution:The small signal diagram is drawn in the right side in Fig. 1 above. Since there is no body effect , according to KCL, we have 02221=+i i (1a)where )()(21out in m s g m gs m v v g v v g v g i −=−== (1b)out ds out ds s d ds ds ds v g v g v v g v g i −=−=−==)0()(22 (1c)Combine Eqs. (1a)-(1c), we have dsm min out g g g v v += (2)2) What is the small signal output resistance out r ? Solution:Following the steps to calculate output resistance. (i) Set v in = 0.(ii) Apply v tst at the output, and draw the small signal diagram as shown below.i 21=g m v i 22=g v =-g v Fig. 2, Small signal diagram for calculating output resistance(iii) According to KCL, we have02221=++tst i i i (3) where tst m tst m s g m gs m v g v g v v g v g i −=−=−==)()(021 (4a)tst ds out ds s d ds ds ds v g v g v v g v g i −=−=−==)()(022(4b) Substitute Eqs. (4a)-(4b) into Eq. (3)tst ds m tst v g g i i i )()(+=+−=2221 (5)(iii) Thus dsm tst tst out g g i v r +==1Common Gate AmplifiersV DDv inFig. 1, Common-gate stage with direct coupling at inputIn a common-gate amplifier, the input signal is applied to the source terminal, as is shown in Fig.1. It senses the input at the source and generate the output at the drain. The gate is connected to a dc voltage to establish proper operating conditions. Note that the bias current of M1 flows through the input signal source.Large signal behaviorFig. 2 Large signal behaviorWhen V in >V B -V T , M1 is off, and Vout is V DD .As V in decreases, so does Vout, M1 is in saturation until()T B D T in B ox n DD V V R V V V LW C V −=−−−2121)(µ (1)After that, M1 is driven into the triode region.Small signal analysisDraw the small-signal diagram below when the transistor works in saturation, assuming 0=λ and 0≠γ,i 22=g mb v bs =-g i 21=g m v gs =-g m v inFig. 3 Small signal diagram to calculate the voltage gainWe can have,in D mb m D in mb in m out v R g g R v g v g v ⋅⋅+=⋅−−−=)()( (1)Thus,)()(η+⋅⋅=⋅+==1D m D mb m inout v R g R g g v vA (2)Example : What is the input impedance of the common gate amplifier discussed above (assuming 0=λ, and 0≠γ)?Solution : To obtain the impedance seen at the source, we use the following equivalent circuit:i 21=g m v gs =-g m v tsti 22=g mb v bs =-gFig. 4 Small signal diagram to calculate the input impedanceAccording to KCL, we have,)(2221i i i tst +−=(1)From Fig. 1, we have tst m tst m s g m gs m v g v g v v g v g i −=−=−==)()(021 (2)tst mb tst mb s b mb bs mb v g v g v v g v g i −=−=−==)()(022 (3)Substitute Eqs. (2)-(3) into Eq. (1), we havetst mb m tst mb m tst v g g v g g i )()(+=+= (4a) Simplify Eq. (4a), we have tst mb m tst v g g i )(+=(4b)Thus mbm tst tst in g g i v r +==1Example: What is the voltage gain of the following amplifier (assuming 0=λ, and 0=γ)?VFig. 1, Original schematic and small signal diagram for calculating small signalvoltage gainSolution:According to KCL, we have, 1121i i =(1)From Fig. 1, we haves m gs m v g v g i 22221−== (2))(in s m sg m v v g v g i −==11122 (3)Substitute Eqs. (2)-(3) into Eq. (1), we have in m m m s v g g g v 211+=(4)ThusD m m m m in D s m in out v R g g gg v R v g v v A 21212+===(5)。

专八满分听力Mini-lecture（1-4）

Mini-lecture 1Cultural UnderstandingLike learning a language，developing cultural understanding occurs step by step over time.Here are five stages of cultural understanding veduchina.Stage one：No understanding.一involves no awareness of the new culture：know nobody and few(1)Stage two：Sup erficial understanding.--awareness of (2) aspects of the foreign culture and stereotypes veduchina--stereotytres are(3)Stage three：Growing understanding and possible(4)--awareness of more subtle，less visible traits in foreign culture--unnecessarily bring acceptance veduchina.For anyone，the home culture is(5)Stage four：Greater(6)————understanding.一still(7) have little empathy veduchina一the(8) level is higherStage five：True empathy，and cultural (9)————.—to live in the foreign culture：the amount of time depends Oil(10)Mini-lecture 2 British Educational System1.Primary and secondary educationin Britain1)Children at the age of(1)________go to primary school.2)Students attend secondaryschool until age sixteen.3)Students enter higher education at age eighteen.2.Higher education in Britain1) In England and Wales：—Application for universities：through the UCCA；一Courses：“course”refers to a(2)_______ program，structured with a fixed program of classes；—Classes：a.classes are offered in the UK on a(3)________basis veduchina；b.more emphasi s i s placed on(4)________study；c.students write more essays and take fewer objective tests；d.classes often take the following forms：(5)______，tutorials，seminars.2) In Scotland：—A variety of tertiary level options are available：a.The colleges of further education provide vocational and (6)____education；b.Central institutions don’t directly validate degrees,but many have close ties to(7) .c.Teachers colleges veduchina；d.The standard university degree is a four—year(8)__________；parison between the US and the UK higher education1)Grading：一In the UK，(9)__________are the most common form of study assessment—The US professors grade less strictly than the UK professors veduchina2)Course levels：—Basic courses are not(10)____________at UK universities.Mini-lecture 3 Mass Media in AmericaMass media specifi cally refer to those publications and programs that attempt to serve most or all of the people in a given market.Three groups of mass media in America are briefly introduced.I. N ewspapersA.Reading newspaper is different from watching TV.—for one thing1.detailed(1)_______ of news items2.substantial treatment of news events3.interesting and stimulating opinions4.analysis over important events at home and abroac—for anotheras for the reading places, no(2)_______B.Newspapers are still a big business.—fact one: the large circulation of a number of important newspapers—fact two: the great (3)_______ of newspapers availableII. MagazinesA.great varietyB.wide range of topi csC.different target readers:the well-educated,well-informed,and(4)_____ peopleD.the top three:(5)_______ TV Guide and The Conde Nast SelectIII. Radio and TelevisionA.Radio:a first-class entertainment medium for most Americans一The future of the radio is still(6)___________B.Television--become popular after the invention of(7)_____ and videotape recorders—profound impact on society1.the socialization effect2.a(8)_________ a molder of new of new cultural trends and a molder of attitudes towards these new trends3.revolutionized the marketing of goods4.the enormous cultural impact of TV violent programs5.the impact of TV on(9)_______________To sum up，the mass media in Ameri ca has，to a great extent，changed and will still keep on changing Americans’(10)_________Mini-lecture 4 Government in Britain and the USThe focus of this lecture is different government systems in Britain and the US.Government in Britain:1. National government:the center of government in Britain iS Parliament.一Location of parliament:(1)__________.—Parliament includes the House of Common，the House of lords and the monarch.—the passage of bills:firstly brought to the House of Commons for discussion，then the house of Lords，finally(2)_________2. Local government in Britain，also known as(3)_________一make small laws,only applied in local area—got payment from(4)from national government--elected by people within each town,city or country areaGovernment in the US:1.The federal government—(5)________is the central law-making body in the US.1)the House of Representatives2)the Senate: the higher but less (6)________of the two houses of Congress.—The President has the power of (7)________a bill.—The Supreme Court: the final Court of Appeal in the US.2.The state government—Each state has its own written(8)________—The highest elected official of each state is the Governor.3.The local government—No law of local government can be(9)________with the United Constitution.To sum up，the government in each country is a (n) (10)________of its historicaland modern factors.参考答案：Mini-lecture1 (1)basi c facts (2)negative (3)offensive (4)conflict (5)much better(6)intellectual (7)emotionally (8)comfort (9)respect (10)the individualCulture understanding文化差异Today I will focus on the i ssue of culture understanding. With increasing globalization, the world becomes really small nowadays. As a member of the global, we get more chances to contact foreign cultures. And what if we want to understand foreign culture very well, what should we do? What kinds of process will we experience before we achieve that goal. The answer is not very difficult to imagine. Just like learning a language, developing culture understanding occurs steps by steps over time. Development of culture consciousness is a process that starts the stage no understanding and moves, in the best case, to the stage of true empathy移情作用,[心]神入and culture respect. So an order to make it a clearer explanation about the process, the five stages of culture understanding is presented here.Stage 1 no und erstanding This level involves no awareness of new culture. The point is quite easy to see. For a person who has few chances to get contact with other cultures, a new one sometimes might as well be like something from an unknown planet in outer space. The person does not know anyone from the culture, and has encountered few, if any, basi c facts about the culture; so naturally, the person certainly has no way to understand that culture at all.Stage 2 superficial understanding This level involves awareness of very superficial aspects of foreign culture, frequentl y negative aspects. At this stage of culture awareness, the person knows a few basic facts of new culture. These facts stand out and often serve as the basis of stereotypes 陈规,老套. However, the stereotypes are offensive because they imply that al l people from a certain culture have the same characteristi cs. At this stage of culture awareness, when stereotypes are keenly felt, the person is highly ethnocentric种族[民族]中心主义的,种族[民族, 集团]优越感的that means the person is just focused on his or her own culture as the norm of what is right and comparing the new culture with the better culture back home. Stage 3 growing und erstanding and possible conflict In this stage the learner begins to be aware of more subtle sometimes less visible traits in the foreign culture. I will give you an example here to illustrate this point. A student learned that a given culture focuses on family far more getting things accomplished. As a result, he or she begin to appreciate the huge importance of family value in this culture, so we can see thi s understanding helps the person to see why things operate the w ay they do. But such awareness doesn’t al ways bring acceptance. In this stage the person is still ethnocentri c home culture-oriented, comparing that culture that i s new to his/her old home culture and usually feel his/her home culture is much better. I think some of you, as English majors, may have the exactly same experiences when you come to be familiar with your foreign t eachers or friends. You do appreciate some of their cultures but you just can’t accept them from the bottom of your heart.Stage 4 great intellectual culture und erstanding At this stage the learner begins to comprehend intellectually the peopl e in the foreign culture yet they are still a little emotional empathy. The person can not feel what it is like to be a member of that culture, the learner thus starts to see things intellectually through the eye of culture bearers at the least part of the time, but they just can’t really feel the same way the members of foreign culture feel. The learner begins to shed ethnocentrism a little bi t and starts to understand new culture more deeply. The person knows why thing are done in the way they are done and accept these things with less irritation. So you can see now the learner obviously comprehend the briefs and actions of people in the culture, the comfort level is higher, and the person does not complain the extensively about the culture differences. That makes a big sense in the process of culture understanding.Stage 5 true empathy and culture resp ect This level is the highest one of culture awareness. To attain this level, the learner must actually live in the foreign culture for some time. As for how long the learner must live in such a culture so that they can reach stage five. The amount of time is variable, greatly depending on the individual. At the fifth stage, unlike the previous stages the learner does not just see things intellectually from the viewpoint of the culture some or most of the time, instead he/she actually feel the part of culture, respects the culture fully and emphasizes emotionally with those who have lived all their life in that culture. By doing so, the person, in real sense, achieves a true culture understanding.In summary, today’s lecture is centered on the stages and growth of culture consciousness. Altogether there are five. 1 no understanding means one does not know anyone from that culture knows few, if any, facts. 2 superficial understanding means one knows some superficial facts and stereotypes. 3 growing understanding and possible conflict means one is aware of moresubtle traits but may experience culture conflicts probably believes one’s own culture is superior. 4 great inte llectual culture understanding means one understands the culture intellectually but not emotionally. 5 true empathy and culture respect means one understands the culture both intellectually and emotionally, can feel what the people in the culture feel. Hope the lecture will be helpful in your nurturing of your culture awareness. Thanks for your patience.Mini-lecture2(1)five (2)degree (3)modular (4)independent/self-directed (5)lectures (6)technical(7)local businesses (8)Honors degree (9)written examinations (10) commonBritish Educational SystemToday I’ll talk about the British educational system, including the primary and secondary education and the higher education in Britain. Meanwhile, I’ll try to make a comparison between the US an d the UK higher education.First, I’ll briefly introduce the primary and secondary education in Britain. In England and Wales, students study in primary schools from age five until eleven. They attend secondary school until age sixteen. Before graduating, students usually take seven comprehensive exams, called the General Certificate of Secondary Education (GCSE) exams. After passing the GCSE exams, students choose to study two to four subjects intensely for the GCE Advanced Level exams, called "A levels." At eighteen, they enter higher education to focus on a parti cular subject, called a "course."Now let’s move on to the higher education in Britain. First I’ll talk about the general practi ces in England and Wales, and then the general practices in Scotland.In England and Wales, prospective university students apply for places through the Universities Central Council on Admissions (UCCA). Students do not apply directly to the universities themselves. Successful candidates are admitted directly into a specific degree "course." A degree course normally takes three or four years to complete. At most universities students study only one major subject. Each course i s structured with a fixed program of classes for the entire three years. Increasingly, universities in the United Kingdom are offering classes on a modular(课程教学)以单元为基础的basis, whi ch allows students to broaden their studies creating a more interdisciplinary program. This modularization, however, has not replaced the traditional British degree course with the American concept of credit accumulation. In addition, there is generally a sharp distinction between the arts and sciences and there is seldom any cross-over between the two.At a British university, more emphasis i s placed on independent, self-directed study than in the United States. Required texts and definite reading assignments are less common. More typi cally, an extensive reading list covering all topi cs to be discussed is di stributed at the start of the course to be used for independent research. British students typically consult a large number of sources from the library rather than intensively studying a few books purchased by everyone taking a course. In addition, students are required to write more essays and take fewer objective tests than at U.S. institutions. Classes often take the following forms: lectures, which are sometimes completely optional; tutorials, in whi ch a small number of students meet with the lecturer; and seminars, larger discussion classes often based upon seminar essays. Unlike the U.S. system of regular testing in a course, British students sit for final examinations that cover the full year's work and determine the grades for the class. With the growth of modularization, however, there has al so been an increase in the number and variety of modules offered on a semester basi s.In Scotland, there are a variety of tertiary第三的,第三位的level options available for students, the most important of whi ch are the colleges of further education, the central institutions, teachers colleges and the universities. The colleges of further education provide vocational and technical education, and enroll more students than all other tertiary institutions combined. Central institutions provide courses leading to the Higher National Diploma (HND), bachelor's degrees and some specialized master's degrees. These institutions do not have the authority to directly validate degrees and tend to offer a narrower range of subjects than the universities. Many have close ties to local businesses, offering cooperative work experiences that provide students a period of practical training.Scottish universities are quite di stinct from their British counterparts. In fact, they more closely resemble European or American universities. The standard Scottish university degree is a four-year Honors degree (BA Hons). Students are rarelyadmitted directly to a degree "course." Usually they are admitted to a faculty or simply admitted to the university as a whole. Scottish university students begin with a broad-based program during the first year and choose a specialization专门[业]化after the second or even the third year. Students may also elect to complete a three-year Ordinary degree. This i s a broad-based degree that (unlike in England) does not represent a "failed" Honors degree.Next, let’s compare the US and the UK highe r education from two aspects,]namely, grading and course levels.First, about the Grading. In the UK, assessment methods vary by institution and tend to reflect the UK teaching method and style. Written examinations, whi ch are held at the end of a year or, in some cases, in the final undergraduate year only, are the most common form of study assessment. There i s no official method of equating British and American educational qualifications. The educational systems are very different and attempts to compare them must be done on a strictly provisional basis. Many U.S. institutions have already developed systems of assessing their study abroad students or equating British grades to U.S. grades.Professors at UK institutions grade more stri ctly than their counterparts in the United States. As a result, American students studying in the UK often perceive that they have performed poorly in their classes, when they have not. Grades are given as percentages rather than letter grades. Forty percent is the minimum passing grade and high percentages are rarely awarded. A grade of seventy percent or higher is considered "with distinction."In general, percentages increase from forty rather than decrease from 100 percent, as they do in the United States.Second, about the Course Levels. A typi cal British course load will vary from 3 to 6 modules or classes per term. Most students take 4 to 5 modules per term. The number of hours in class per week will vary by institution. Students should note that general education or basi c courses are not as common at UK universities because they have already been covered at the GCSE level. Many faculties assume that a student has a basi c understanding of the concepts that will be addressed in the course. For this reason, it is common for third-year American students to take first-year and second-year courses at a UK university.With thi s, we’re coming to the end of today’s lecture. Next time, we’ll talk about university degrees.Mini-lecture3 (1)coverage (2) limitation/confinement (3) variety(4)public—conscious(5) Reader’s Digest (6) promising/bright (7)portable cameras (8) transmitter (9) religion (10)lifeMass Media in America美国媒体Good morning, everyone,today my topic i s mass media in America. By media, we refer to the variety of means by which technology transmits information and entertainment to us. Thus, in its broadest sense, the term media includes newspaper, television, movies, radio, books, and magazines. Mass media specifi cally refer to those publications and programs that attempt to serve most or all of the people in a given market. Here I would like to introduce the mass media in America by dividing them into three groups: newspaper; magazines; radio and television.First, let’s have a look at newspapers. For a long time, newspapers have been the chief means by whi ch people get themselves informed. While television has replaced newspapers as the primary source of news for most Americans, and while computer network is increasingly becoming a faster and easier way of obtaining news for many Americans, newspapers still remain as one of the most powerful means of communications in the United States. For one thing, reading newspapers i s different from watching TV. It gives detailed coverage报道范围of news items, and tends to provide substantial treatment of news events. And, sometimes it offers interesting and stimulating opinions as well as analysis over important events at home and abroad. For another, unlike watching TV, reading newspapers does not require one to be confined to his sitting-room. He can do it virtually anywhere he likes: in his car, at the breakfast table, sitting in the sun, waiting at the subway station, and believe it or not, in the restroom. So, for these and many other reasons, newspapers in the United States are still a big bus iness. And, this is borne out by two facts: (1) the large circulation of a number of important newspapers such as USA Today《今日美国》and The Wall Street Journal《华尔街日报》; (2) the great variety of newspapers available in the United States, big and small, local and national, special and general, radical and conservative, and so on. The top 3 daily newspapers in the United States are: Wall Street Journal, USA Today and New York Times《纽约时报》.Second, we’ll move to magazines. According to a statisti cal record in 1990, there were over 12,205 magazines being published in the United States. More than 4,000 of them appear monthly, and over 1,300 are published each week. They cover all topics and interests, from art and architecture to sports, from aviation航空学,飞机制造业and gardening to computers and book reviews, from fashion design and cooking to homemaking. Quite a few have international editors, are translated into other languages, or have “daughter” editions in foreign countries. Among the many internationals are National Geographic《国家地理》杂志, Reader’s Digest《读者文摘》杂志,Cosmopolitan《大都会》,Vogue《时尚》杂志,Time《时代》,Newsweek 《新闻周刊》, Scientific American and Psychology Today. The weekly newsmagazines —the best known are Time, Newsweek, and U.S. News & World Report《美国新闻与世界报道》—serve as a type of national press. Unlike newspapers, however, weekly newsmagazines tend to give extensive coverage and provide detailed, and sometimes in-depth, analysis. Also unlike newspapers, whi ch usually have the lowest common denominator in their appeal to the general reading public, weekly newsmagazines normally target at the well-educated, well-informed, and public-conscious people of the society. Many weekly newsmagazines also have considerable international impact, particularly Time and Newsweek. The top three magazines in America are: (1) Reader’s Digest; (2) TV Guide《电视导读》; (3) The Conde Nast Select.Third, I’ll say something about radio and television. In more than two generations, the two powerful mass media transformed much of American life.Radio, emerging at the same period when the Great Depression pervaded蔓延, 在…中盛行in America, provided free entertainment in the comforts of the home. Families that could no longer afford to go out for entertainment gathered together in their living rooms to escape reality by laughing, fantasizing梦想,幻想and dreaming of happier times. From then on, radio became a first-class entertainment medium for most Ameri cans. Up until now, in view of the popularity of radio programs in the United States, the future of radio as a form of medium continues to look bright.Then, with the rapid development of science and technology, TV came into being in 1920s. It primarily serves as a medium of entertainment, and then also has a big role to play as a news broadcasting agency. Networks began experimenting with news at locally owned stations as early as January 1940. But, early-day television news could not begin to compare with radio news. Only after the invention of portable cameras and videotape recorders had television been made a much more credible news medium because viewers saw pictures of the news events on the day they occurred. Consequently, access to news is made much easier, and the general public is getting better informed.Gradually, television’s impact on American society has been more and more profound. It has changed the life-styles of most Americans and become a major influence on American culture. It can be seen from 5 aspects.First and foremost is the socialization effect. Many studies have shown that TV’s dominance as household activi ty often reduces the level of communi cation among family members and, as a result, much of the culture being distributed to youngsters today in the United States comes from the tube rather than the family.Secondly, television programming has played an important role in shaping and reflecting for the masses the cultural changes that have been occurring in American Society. TV functions both as a transmitter传送[递]者of new cultural trends and as a molder造型者,模塑者of new attitudes towards these new trends.Thirdly, television has revolutionized the marketing of goods in the Ameri can economy. With TV marketing, people become vulnerable to the products, or in other words, to the commercials.Fourthly, the cultural impact of violent TV programs has been quite enormous. Needless to say, the question of violence on TV has been around nearly as long as the medium. Many critics claim that TV violence increases violence in American society.Fifthly, the impact of TV on religion has al so been an issue of great concern to many Americans. So far now, it is still an issue full of di sputes.To sum up, the mass media in Ameri ca includes so many different forms, and each of them plays a vital role in American people’s life not only in the past, but also at present and in the future. To know much about America, one must have a good knowledge about its mass media.Mini-lecture4 (1)Westminster (2)signed (3)Councils (4)local taxes (5)Congress (6)powerful(7)veto (8)Constitution (9)in di sagreement (10)embodimentGovernment in Britain and the US英美政府Today we will focus on the Government in Britain and the United States. Let’s have a look at them one after the other.Government in Britain can be divided into National government and Local government.The center of government in Britain is Parliament, which makes all the important laws for the country about crimes and punishment, taxation课税, etc. Parliament i s made up of the House of Commons, the House of Lords and the monarch. The Houses of Parliament are in Westminster in London and sometimes “Westminster” itself i s used to mean Parliament.The House of commons, or the Commons, is the lower but more powerful of the two Houses. It has 650 elected members, called Members of Parliament or MPs, each representing people in a parti cular area or constituency(议员所代表的)(全体)选民;选(举)区. The House of Lords上议院, or the Lords, is the higher but less powerful of the two Houses. It has over 1,000 members, none of whom is elected. These members include: people who have titles like Lord or Viscount子爵whi ch have been passed down to them on the death of their father; people who are given titles as a reward for their long servi ce in public life, but whose children do not inherit their title; and some important leaders of the Church of England, such as Archbishops and Bishops.The government brings bills to the House of Commons下议院, whi ch are discussed by MPs. The bills then go to the House of Lords to be di scussed. The House of Lords can suggest changes to a bill, but does not have the power to reject it. When bills come back to the Commons, MPs vote on them and if they are passed they are signed by the monarch and become Acts of Parliament.At present England, Scotland, Wales, and Northern Ireland are all governed by Parliament in Westminster. In Northern Ireland the political parties are different but their MPs still go to the House of Commons. In Scotland there is a lot of di scussion about whether Scotland should have some separate or partly separate form of government. The same is true in Wales. The Local government in Britain, also known as Councils, can make small laws, that i s bylaws, whi ch only apply in their area, but these are usually about small, local matters. For instance, they may be about fines that will be made for people who park in certain streets.Councils are paid for by local taxes and also by an amount of money given to them each year by the national government. Their main job is the organizing and providing of local services, e.g. hospitals, schools, libraries, public transport, street-cleaning, etc. They are also responsible for setting the amount of local tax that people must pay and for collecting thi s tax.Local councils are elected by people within each town, city, or county area. The people who are elected, known as councilors, usually represent one of the national political parties, but are often elected because of their policies on local issues rather than the national policies of their party.Now let’s move to the topi c of Government in the US. All levels of government in the US, including federal, state, and local, are elected by the people of the country.First, we’ll talk about the federal government. The constitution of the US specifi cally limits the power of the federal, or national, government mainly to defense, foreign affairs, printing money, controlling trade and relations between the states, and protecting human rights. The federal government is made up of the Congress , the President, and the Supreme Court. Congress, the central law-making body in the US, i s made up of the House of Representatives and the Senate. The House of Representatives is the lower but more important of the two houses of Congress. It has 435 members, called Representatives or Congressmen. The number of Representatives for each state depends on the size of the population of the state, with each state having at least one Representative. The Senate i s the higher but less powerful of the two houses of Congress. It has 100 members, called Senators, elected by their state. Each state has two Senators. Congress decides whether a BILL becomes law. If the Senate and the House of Representatives both agree to a bill, the President i s asked to agree. The President can veto the bill, but Congress can still make it a law if 2/3 of the members of each house agree to it.Second, we’ll learn something about the state government. The state government has the greatest influence in people’s daily lives. Each state has its own written Constitution, and among the states there are sometimes great differences in law on matters such as property, crime, health and education. The highest elected official of each state is the Governor. Each state also has one。

lecture05哈工大软件学院c++教学课件

© 版权所有哈尔滨工业大学（威海）软件学院
The C++IBM research Programming Language
© 版权所有哈尔滨工业大学（威海）软件学院
… digit1 digit2 digit4 digit5
= = = =
number number number number
/ % % %
10000; 10000 / 1000; 10000 % 1000 % 100 / 10; 10000 % 1000 % 100 % 10;
for statement examples Vary control variable from 1 to 100 in increments of 1 for ( int i = 1; i <= 100; i++ ) Vary control variable from 100 to 1 in increments of -1 for ( int i = 100; i >= 1; i-- ) Vary control variable from 7 to 77 in steps of 7 for ( int i = 7; i <= 77; i += 7 )
The C++IBM research Programming Language
C++程序设计
© 版权所有哈尔滨工业大学（威海）软件学院
The C++IBM research Programming Language
上节课内容回顾
1. if、if…else、while 2. 计数器控制的循环和标记控制的循环 3. 确定ATM系统中类的属性

ccer05研究生数理经济学讲义2

Lecture Notes 1 & 2Optimizing TheoryChapter 1 Unconstrained OptimizationTheorem 1.1 Suppose :n f R R → is differentiable and n x R ∈ is a local maximizer or local minimizer of f , then ()0f x ∇=.Theorem 1.2 Suppose :n f R R →is twice continuously differentiable and (')0f x ∇=.1. If 'x is a local maximizer, then matrix 2(')D f x is negative semi-definite.2. If 2(')D f x is negative definite, then x’ is a local maximizer.Theorem 1.3 Suppose function :n f R R → is concave. If (')0f x ∇=, then x’ is a global maximizer of f .Theorem 1.4 (Envelope Theorem) Consider unconstrained optimization problem:n x RMax ∈(,)f x a , where m a R ∈ is the vector of parameters. The function (,)f x a is continuous and differentiable. Suppose the solution point is **()x x a =. Denote ()((),)V a f x a a =. Then we must have*()(,)()j j V a f x a x x a a a ∂∂==∂∂ , 1,,j m =".Chapter 2 Constrained optimization2.1 The general structureThe variables of the problem will be considered to be in the form of a vector in n R . In addition to this vector, x , we have:a. a feasible set K. Only x K ∈ is to be taken into account in the problem.b. A continuous objective function, ()f x , whose value for x K ∈ is to be optimized.Thus we can state a typical maximizing problem in formal terms asFind *x K ∈ such that *()()f x f x ≥, for all x K ∈.If such an *x exists, the problem has a weak global maximum-weak because itsatisfies the weak inequality, global because the inequality is satisfied for all x K ∈. A global optimum should not be confused with an unconstrained optimum. The latter implies that n K R =. We would have a strong maximum if we could find *x such that *()()f x f x >, for all x K ∈.A weak optimum is equivalent to a non-unique optimum point since any x satisfying *()()f x f x = is also an optimum point. A strong global optimum implies a unique optimum.If we reverse the inequalities we obtain a minimum, weak or strong as the case may be. A minimum for ()f x implies a maximum for [-()f x ]. The value *x is often called simply the solution of the optimum problem. To avoid confusion with other claimants for the same name in many economic models, we shall usually call it the optimal solution or optimum point.Most calculus techniques cannot solve the problem as set out above, but can only solve a problem of the following kind:Find *x K ∈ such that *()()f x f x ≥, for all ()x N K ∈∩,where N is a neighborhood of *x .Such a point is a weak local maximum. We can have a weak or strong local maximum, and weak, or strong local minimum.It is obvious that a global optimum must also be a local optimum. Nevertheless, a local optimum is not necessarily global. Our interest is primarily in the global optimum. Thus, we are interested in conditions on the structure of the problem that will guarantee that a local optimum is also global. If such conditions are not satisfied, we need to adopt ad hoc procedures to locate the global optimum.2.2 Constraints and the Feasible SetThe feasible set, over which the variables are permitted to range, may be defined in any suitable way. In the case of discrete variables, the feasible set may even be described by enumeration. Typically, however, the feasible set will be defined by equalities or inequalities involving relationships between the variables.The boundaries of the feasible set are crucial in optimizing problems. In all our discussions of optimizing, it will be assumed that the constraints are such that as to give a closed feasible set. Otherwise the problem is usually without a solution. This is normally guaranteed by ensuring that there are no strict inequalities in any of the constrains and that the constraints are continuous.When there are several constraints, given a feasible point x ’, we say that a particular constraint is effective at x ’ if x ’ gives an equality in the constraint, ineffective at x ’ if it gives an inequality. Note that a constraint may be “effective” in a common sense meaning without being effective this technical sense.2.3 The General Optimizing ProblemThe Standard format:Max ()f x , n x R ∈, s.t. (1) ()0,i g x ≤ 1,...,i m =; (2) 0k x ≥, {1,...,}k S n ∈⊂. Function ()f x is the objective function; x is the variable vector of the problem. The constraints (1) are the functional constraints, the constraints (2) are the direct constraints. The functions are assumed to be continuous.It is convenient to have all the inequalities in the same direction in the same direction in a standard form. Obviously 00f f ≥⇔−≤.The functional constraints can always be put in inequality form by noting that 00&0f f f =⇔≤−≤. For a very important case of the general problem, all the constraints are equalities and it is then easier to drop the inequality form.The direct constraints will always be written in the nonnegative form. The inequalities in both the functional and direct constraints are assumed always to be weak inequalities to ensure that the feasible set is closed.An optimum problem need not have a solution in general. However, we do have a guarantee that the problem is worth pursuing in a large class of cases:Theorem 2.1 (Weierstrass): A continuous function defined over a nonempty closed bounded set attains a maximum and a minimum at least once over the set.Since we usually take the objective function to be continuous and the feasible set to be closed, the boundedness of the feasible set is the only condition that is not ensured. Nevertheless, Weierstrass theorem gives sufficient but not necessary conditions to the existence of a solution of an optimum problem.2.4 The General Solution PrincipleAn optimal point must be in the feasible set but may be either an interior point or a boundary point. If it is an interior point, it has a neighborhood of feasible points and must be an optimum relative to those neighborhood points. Such a point must satisfy the ordinary calculus conditions for an unconstrained optimum. A boundary point has a neighborhood that includes infeasible points as well as feasible ones, and it is not possible to say that such a point must be optimal relative to its neighborhood. A boundary optimal point need not be critical point of f .f x are Proposition 2.2 The solution to the general optimum problem, where ()f x for x over some closed feasible set K will, if it exists, be some differentiable, Max()f x, or (b) a boundary point of K (or both). point x’ which is: (a) a critical point of ()In principle, an optimum problem can be solved by finding the critical points of ()f x along the boundary, finally choosing the f x, then computing the values of ()f x is not differentiablef x. If ()point giving the maximum or minimum of ()everywhere, the points at which it is not differentiable will need to be examined in addition to the critical and boundary points.2.5 Conditions for a Global optimumSince we are usually interested in a global optimum and since many techniques discover only local optima, conditions which guarantee that a local optimum is also a global optimum are of great value. The particular conditions set out below are of special importance because they are satisfied by most typical optimum problems in economicsf x Proposition 2.3 For problem concerned with optimizing a continuous function ()f x over a closed feasible set K, every local optimum is also a global optimum if: (a) () is a concave function for a maximum, or convex function for a minimum; and (b) K is a convex set.f x is strictly concave over a convex feasible set the global Proposition 2.4 If ()optimum is unique.Chapter 3 Classical Calculus Methods3.1 IntroductionClassical calculus methods deal with problem with the following properties:a). The objective and indirect constraint functions possess suitable continuityproperties. Usually they will be taken to be of class 2C.b). The functional constraints are equalities.c). There are no direct (non-negativity) constraints on the variablesThe standard form of the problem will be written asMax ()f x , s.t. ()0,i g x = i =1,…,m (m<n )Since the constraints are all effective at all times, the feasible set K contains only boundary points, so interior optima are ruled out. Unless the constraints are all linear, K will not necessarily be a convex set.If the appropriate Jacobean is nonsingular, we can express n-m of the variables in terms of the remaining m (from the implicit function theorem). Hence, we can reduce the problem to one of the unconstrained optimization of a function of only n-m variables. However, explicit solution of the constraint equations is possible only in a few cases, if these are nonlinear.3.2 The Lagrangean FunctionLet us examine the properties of a function 1(,)()()mi i i L x f x g x λλ==−∑, wherethe λ’s are arbitrary variables. The function (,)L x λ is called the Lagrangean function, and the λ’s are Lagrange multipliers.If we take the derivatives of (,)L x λ with respect to the λ’s, we have (,)/()0i i L x g x λλ∂∂=−= for x K ∈. Hence if (,)L x λhas a critical point at ','x λ, then 'x K ∈. Also for x K ∈, (,)L x λ=()f x . It can be shown that if x ’ maximizes f(x) over K, there is some 'λ such that (','x λ) is a critical point of (',')L x λ. The results hold for a minimum as well as a maximum.To use the Lagrange technique, we set up the Lagrangean and then find its critical point(s). The partial derivatives of (,)L x λ with respect to λ’s are simply the constraint functions and equating them to zero merely ensures that x K ∈. It is the partial derivatives with respect to the x ’s that play the major solution role. If these are equated to zero, we obtain n equations of:1mi j i j i f g λ==∑, (1,...,)j n = We can write it as f G λ∇=, where []ij G g = and []i λλ=3.3 Interpretation of the Lagrange MultipliersConsider a standard classical optimizing problem, solved by the Lagrangean technique to give solution values ','x λ. Let the i th constraint be of the form ()i i g x b =. Initially suppose 0i b =. We wish to examine the result of a small relaxation of thisconstraint.Denote the optimal value of the objective function by V’. Now a small relaxation in the i th constraint will permit small changes in the optimal values of the variables, but we assume the optimum conditions remain satisfied so that the new position reached as a result of this relaxation is also optimal. The effect on the optimal value of the objective function will be given by '(')j j i j i x V f x b x b ∂∂∂=∂∂∂∑ (1)From the constraints we have 0(')1k j j j i x k i g x k i x b ∂≠⎧∂=⎨=∂∂⎩∑ (2)If we multiple the k th equation in (2) by 'k λ, and sum over k , we obtain''(')k j ki k j j i x g x x b λλ∂∂=∂∂∑∑ With (1), we have''(')[i j i j V f x b x λ∂∂=+−∂∂∑(')]k j k kj i x g x x b λ∂∂∂∂∑='i λ Thus 'k λ corresponds to the marginal rate of change of the optimal value of the objective function with respect to a small relaxation of the i th constraint, other constraints being unchanged. In typical economic applications, the constraints might be resource limitations and the objective function is index of some social welfare. The optimal Lagrange multipliers would then correspond to the marginal social valuation of the resources.Proposition 3.1 (Envelope theorem) Let (,)f x r and (,)i g x r for i =1,…,m be continuously differentiable functions of the n+k variables. Consider the following optimizing problem:x Max (,)f x r , s.t. (,)0,i g x r = i =1,…,m (n x R ∈, m<n, k r R ∈)Denote the solution of the problem as *()x r , and **()((),)f r f x r r =. Suppose *()x r and the associated Lagrange multipliers 1,...,m λλ are continuously differentiablefunctions of r and the rank of the *[()]ij g x is m . Then**()(,)h hf r L x r r r ∂∂=∂∂ for h=1,…,k ,where 1(,)(,)(,)mi i i L x r f x r g x r λ==−∑.Example : Consider a utility maximization problem: xMax ()u x , s.t. p x w ⋅= Denote the solution of the problem by *(,)x p w , and *(,)((,))v p w u x p w ≡. Function (,)v p w is known as the indirect utility function . By the envelope theorem, we have**(,)(,)(,)i i v p w p w x p w p λ∂=−⋅∂, and *(,)(,)v p w p w wλ∂=∂. Hence we have*/(,)/i v p x p w v w∂∂=−∂∂. This result is known as Roy’s Identity .Chapter 4 Advanced Optimizing Theory4.1 IntroductionThe classical method, assumes both equality in the functional constraints and the absence of direct constraints on the variables. Although this method is widely employed in economic analysis, the fact is that most economic problems have implicit, if not explicit, properties that do not entirely fit the classical case. Nonnegative constraints on at least some variables are usually implicit, and the functional constraints may be more accurately described by inequalities than equalities. Consider the following problem of a consumer.Max 12(1)(1)u x x =++, s.t. 1241x x +=If we solve the problem, using traditional methods, we obtain the optimal values for x as *(1/4,2)x =−, with the optimal level of utility, *9/4u =. Direct calculation shows, however, that (0,1) is optimal, given the nonnegative condition.4.2 Nonnegative VariablesThe most straightforward extension of the classical calculus method is to the case in which some or all of the variables are subject to direct constraints. Consider thisMax f(x) s.t. ()0i g x =, (1,...,i m =), 0x ≥. (3)We can define the function (,)L x λ in the usual way. Three situations are possible. a). (,)L x λ has a regular local maximum at a critical point **(,)x λ, with *0x >, andthe problem satisfies the strong global optimum conditions.b). (,)L x λ has a regular local maximum at a critical point, with *0x >, but the strong global optimal conditions are not satisfied.c). (,)L x λ does not have a critical point with *0x >, which is also a local maximum.The first case is presumed to occur in traditional economic analysis. In the third case, the global optimum must be at a point at which some non-negativity constraint is operative. In the second case it might be at such a point, and will usually need to check.Still with problem (3), consider the properties of (,)L x λ and ()f x at a point x K ∈ at which 0k x = for at least one k . Since the functional constraints 0i g = are still equalities, the maxima of (,)L x λ and ()f x , x K ∈ still occur at the same point *x . Also we still have /0i L λ∂∂=, but what about the first order conditions /0j L x ∂∂=? In general, they might not all be satisfied.Define (){{1,...,}|0}i S x i n x =∈=. If ()j S x ∉, small variations in j x are possible in both positive and negative directions, so that x cannot be optimal unless /0j L x ∂∂=. If ()j S x ∈, small variations in j x are possible in the positive directiononly, so that x cannot be optimal if /0j L x ∂∂>. But small variations are not possible inthe negative direction, so we cannot rule out /0j L x ∂∂< asnon-optimal.Proposition 4.1 The optimal point *x of the problem (1) satisfies the following conditions: 1) ***1(,)0m i j i j i j L x f g x λλ=∂=−≤∂∑, and ****(,)0j j L x x x λ∂⋅=∂, 1,...,j n =. 2) ***(,)()0i iL x g x λλ∂=−=∂Example Let us return to the earlier example, which shall be stated asMax 12(1)(1)u x x =++, s.t. 1241x x +=; 12,0x x ≥The first order derivatives are 12/14L x x λ∂∂=+−, 21/1L x x λ∂∂=+−, and12/41L x x λ∂∂=+−. We already know that there is no critical point of L with 12,0x x >. Now we try putting 1x , then 2x to zero, given the budget constraints. At (0,1), we have21/110L x x λλ∂∂=+−=−=, whichgives 1λ=. 12/14L x x λ∂∂=+−= -2. U =2At (1/4,0), we have12/14140L x x λλ∂∂=+−=−=, which gives 1/4λ=. 21/11L x x λ∂∂=+−=>0, So (1/4, 0) is not an optimal point.There is no universal rule for determining which variables, when put to zero, are likely to lead to an optimal solution. In principle, we may have to try putting one variable at a time to zero, then two at a time, three at a time, and so on, and then compare the results of all cases that satisfy the optimal conditions.In economic analysis, however, we are usually interested in what happens to the optimal conditions when we do have a solution on the nonnegative boundary, and to this we have the answer. Furthermore, boundary problems of this kind in economic frequently occur as the result of a movement to the boundary from an interior point as some parameter is changed, so that the zero variables are specified for us.4.3 Inequality ConstraintsWe now consider the general optimum problem, with the two restrictions of the classical calculus method removed:Max ()f x s.t. ()0i g x ≤, (1,...,i m =), 0x ≥. (4)The problem can be converted into the case discussed in the preceding section by adding slack variables i z to give the i th constraint as ()0i i g x z +=, 0i z ≥.There are now n+m variables in the problem, an n -vector of x variables and an m -vector of z variables, with non-negativity constraints on all. We form the Lagrangean1(,,)()(())m i i i i L x z f x g x z λλ==−+∑=11()()m mii i i i i f x g x z λλ==−−∑∑ The optimal conditions with respect to j x are as before. The optimal conditionswith respect to i z are ***(,)0i i L x z λλ∂=−≤∂, and 0i i z λ=. These conditions impose no direct constraints on x , Their content is entirely represented by the equivalent statement()0i g x ≤, (1,...,i m =), 0λ≥, and 1()0miii g x λ==∑. Thus if we form the Lagrangean, ignoring the inequalities in the functional constraints, as 1(,)()()mi i i L x f x g x λλ==−∑, adding the non-negativity constraint 0λ≥,all points which are optimal for z in (,,)L x z λ satisfy (,,)L x z λ(,)L x λ=. Consider (,)()i iL x g x λλ∂=−∂. From the constraints we have ()0i g x ≤, and from the optimal conditions with respect to z in (,,)L x z λ, we have 0λ≥ and ()0i i g x λ⋅=. These together imply (,)0iL x λλ∂≥∂ and (,)0i i L x λλλ∂⋅=∂. The above conditions can be recognized as the conditions for a minimum of (,)L x λ with respect to λ, given the non-negativity constraint 0λ≥.How does it come about that, although we are seeking a maximum for ()f x subject to the constraints, and although we were able to treat (,)L x λ as having a maximum with respect to x in the strict classical case, we now seek a minimum with respect to λ of the expression that is analogous to the strict classical Lagrangean?First, we note that, in the strict classical case, if (,)L x λ is neutral with respect to changes in λ over the feasible set, we would have regarded (,)L x λ as having a minimum with respect to λ just as well as having a maximum.Second, we note that at any optimal point of (,)L x λ, whatever a maximum or a minimum with respect to λ, we have (,)L x λ()f x =. Whether a maximum or a minimum is involved, with respect to λ, is related to the constraints but not to the objective function.Third, consider an effect of a small variation in λ from its optimal value *λ. If*λ>0, then **(,)L x λ isunchanged. If *λ=0, we may have *()0i g x <. Because of the nonnegative constraint on λ, the only permissible variation is to some small positive value. In this case, the term ()i i g x λ− in the expression of **(,)L x λ will take on apositive value and we will have *(,')L x λ>**(,)L x λ. Thus, the optimal point gives a minimum of (,)L x λ. The minimum property will only be apparent when at least one constraint is ineffective.Proposition 4.2 (Kuhn-Tucker Conditions) The optimal point *x of the problem (4) satisfies the following conditions: (1) ***1(,)0m i j i j i j L x f g x λλ=∂=−≤∂∑; ****(,)0j jL x x x λ∂⋅=∂, 1,...,j n =. (2) *()0i g x ≤, and *0λ≥; **()0i i g x λ⋅=.If the problem is one of minimizing, the direction of the inequalities in (1) is reversed. If we are not trying to discover whether a certain point is optimal or not, but are merely interested in the properties of a point already known to be optimal, conditions (2) state that we can ignore ineffective constraints at the optimum.We have noted that (,)L x λ, a function of two sets of variables, has a maximum with respect to x and minimum with respect to λ at the optimum. A point which gives a maximum of a function with respect to some variables, and minimum with respect to others, is called a saddle point, a term descriptive of the shape of the function in three dimensions.4.5 Existence of Optimal SolutionsConsider the Lagrangean written in the form 1(,)()()mi i i L x f x g x λλ==−∑, with theconstraints 0,0,x λ≥≥()0i g x ≤. We see that (,)L x λ is a concave function of x if ()f x is concave and each ()i g x is convex. Considering the sets over which ,x λ are confined, since λ is defined on a convex set and the set {|()0}i x g x ≤ is convex when ()i g x is convex, the feasible set is the intersection of convex sets and is convex.We still need the sets to be compact. The nature of the constraint inequalities ensures that they are closed, so it remains to consider boundedness. Since we seek a minimum for λ, and it is bounded below by the non-negativity constraint, we can impose an arbitrary upper bound so large it does not affect the optimal solution. The feasible set for x presents the difficulties. We cannot avoid adding the special assumption that thefeasible set is bounded.Thus if ()f x is concave, every ()i g x is convex and the feasible sets is bounded, the Lagrangean satisfies the conditions of Theorem 4.4, so that is possesses a saddle point and the general optimizing problem possesses a solution. Furthermore, the conditions for a global optimum are satisfied by the same convexity-concavity conditions. Thus we haveTheorem 4.5 The general maximum problem ()Maxf x s.t. ()0i g x ≤, (1,...,i m =), 0x ≥. Always possesses a solution if:a). ()f x is concave and every ()i g x is convex;b). the feasible set {|()0,1,...,;0}i K x g x i n x =≤=≥ is bounded and nonempty.Under these conditions the Lagrangean 1(,)()()mi i i L x f x g x λλ==−∑ possesses asaddle point **,x λ, where *x is optimal in the maximum problem and *0λ≥. Furthermore, the values **,x λ satisfy the Kuhn-Tucker conditions, which are then sufficient for a global optimum. If ()f x is strictly concave, the point *x is unique.Homework:1. If 221122()2f x x bx x x =++, what values of b give: a). a local maximum of f(x), s.t. 121x x += ?b). a local minimum for f(x), s.t. 121x x += ?2. The welfare function for a two-good, two-person economy is 112a a W u u −=. Theindividual utility functions are 111121b b u x x −=, 121222c c u x x −=, where ij x is the amount of thei th good consumed by the j th individual.If the total amounts of the two goods are fixed, what is the optimum allocation between the two individuals? (Assume ,,]0,1[a b c ∈)3. Discuss the nature of the optimum solution for different values of a in the problem:Max 221210(2)(2)x x −−−− s.t. 22121x x +≤, 12x x a +≤, 120,0x x ≥≥.。

Lecture_05-I

of the deviation variable h’
4
Analysis of Single Loop Systems
PID Controllers
An
example
e(t) = hs(t)-h(t)
Defining an error signal due to the use of negative feedback
p ' (t )
TimeDomain
S-Domain
10
Analysis of Single Loop Systems
PID Controllers
P-control:
11
Analysis of Single Loop Systems
PID Controllers
P-control:
Modern
The lower PB, the faster (and less stable) control.
15
Analysis of Single Loop Systems
PID Controllers
The Percent Proportional Band
From Practical perspective:
Level Sensor
12
Analysis of Single Loop Systems
PID Controllers: P-control:
13
Analysis of Single Loop Systems
PID Controllers
In
the sens of proportional gain Kc
The higher gain, the faster (less stable) control. The lower gain, the slower (more stable) control.

Lecture05-造船生产计划准备工作

编制施工要领的目的
Ì 贯彻落实建造方针，达到预订的综合目贯彻落实建造方针，
收到预期的经济效益。标，收到预期的经济效益。 Ì 将各专业和各阶段的施工工艺，技术要将各专业和各阶段的施工工艺，求和作业顺序、求和作业顺序、作业方法等详细地加以系统的综合和协调。系统的综合和协调。 Ì 指导生产设计，施工要领的内容要反映指导生产设计，到各专业生产设计的图表和技术文件中。到各专业生产设计的图表和技术文件中。 Ì 指导生产和管理。指导生产和管理。
生产设计准备
辛国栋 gdxin@
主要内容
Ì 分段划分 Ì 施工要领的编制 Ì 生产设计计划准备
生产设计准备定义
Ì 生产设计准备是在开展生产设计之前，生产设计准备是在开展生产设计之前，
从全厂性、全船性、从全厂性、全船性、综合性的角度对设生产和管理等工作进行技术技术和计、生产和管理等工作进行技术和计划方面的前期沟通和协调。方面的前期沟通和协调。
r 它主要由船厂生产负荷计划、各阶段负荷计它主要由船厂生产负荷计划、
划和分阶段负荷计划三部分组成。划和分阶段负荷计划三部分组成。
船厂生产负荷计划船厂生产负荷计划生产
Ì 含义及作用
r
产品配置
预测潜在合同客户主生产计划 ( MPS ) 粗能力计划 ( RCCP ) 可行？物料需求计划 ( MRP ) 能力需求计划 ( CRP ) 可行？执行物料计划 ( 加工、采购 ) 执行能力计划 (投入/产出控制)
Ì 将1、2年内每个月的各种船舶曲线的年内每个月的各种船舶S曲线的、年内每个月的各种船舶
负荷值叠加，可以得出、年内各月工负荷值叠加，可以得出1、2年内各月工厂主要车间的负荷分布累计图。厂主要车间的负荷分布累计图。

RM lecture 05 handout

11
Zero or Spot rates
A zero rate (or spot rate), for maturity T is the rate of interest earned on an investment that provides a payoff only at time T A chart of spot rates against maturity is called the yield curve or term-structure of interest rates Term structure animation /freecharts/yieldcurve.php
– Eurodollar futures and swaps are used to extend the LIBOR yield curve beyond one year – The overnight indexed swap rate is increasingly being used instead of LIBOR as the risk-free rate
Measuring Interest Rates
The compounding frequency used for an interest rate is the unit of measurement
The difference between semi-annual and annual compounding is analogous to the difference between miles and kilometers E.g. a $100 investment can yield $105 (100 principal + $5 interest) in multiple ways

Lecture_05

从问题到程序
9
复杂关系，如： 3≤x≤5 时 z 取值 2，否则取值 1。可以用关系表达式和条件表达式描述：
z = (x >= 3 ? (x <= 5 ? 2 : 1) : 1);

有了关系表达式和条件表达式，足以描述任何可能的复杂条件。但写出的描述可能比较复杂，不太直观逻辑运算符专门用于基于简单的逻辑构造复杂的逻辑关系。用逻辑运算符可直接描述
只能写出平铺直叙的直线型程序。这种程序从头开始执
行，一个个语句执行到最后
不能区分情况，不能用简单方式描述重复的类似动作

例如，要写一个函数，返回两参数中的较大值：
double dmax (double, double) 需要：
比较数据大小（判断）根据判断结果决定做什么（分情况处理）

函数 dmax 的定义：
double dmax (double x, double y) { return x > y ? x : y; }

例：z = dmax(2, 3);
注意它的计算过程
条件表达式

从问题到程序
8
符号函数 sign对应的C函数： double sign (double x) { return x > 0 ? 1 : (x == 0 ? 0 : -1); }

这里假定了a不为0，处理a为0的情况也不困难（加判断）
连续 if 条件判断

从问题到程序
22
前例中出现了连续的条件判断：
成立时做某些操作不成立时判断下一条件

这种情况下的建议书写形式（清晰，又不会退格太多）： if (...) { ... ... } else if (...) { ... ... } ... ... else { ... ... }

华中科技大学费剑平高级微观经济学课程讲义 Lecture05

Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 1Lecture 05 Optimization and Firms IV: Cost FunctionThe cost function c(w, y)= wx (w, y) measures the minimum cost of producing a givenlevel of output for some fixed factor prices. As such it summarizes information about the technological choices available to the firms. It turns out that the behavior of the cost function can tell us a lot about the nature of the firm’s technology.If we have the economic data we can recover things like the demand function for factors of production for the firm just by taking derivatives of costs functions with respect to prices.These cost functions in general will have a particular shape, namely they will be concave. This is equivalent to just thinking about the value of information. This is equivalent to saying that the ability to make decisions when we know the realization of a random variable is more valuable than having to make our decision based simply on the distribution from which that random variable is chosen. And that observation is equivalent to saying that these cost functions must be concave in prices regardless of the shape of the underlying technology or isoquant.The objective here is to get you to learn how to describe the technology of a firm. The most common way in intermediate course is production function. In this lecture, we will discuss some economically relevant aspects of a firm’ technology.1. Total cost ,average cost and marginal cost.We will graph cost as a function of output and hold the factor prices constant. It is understood that factor prices are included but they will not be changing. Let’s start with asimple case. Suppose that the only factor of production that is variable is labor and that there is a fixed cost. First, let’s draw a graph for the isoquants. See figure 1.wL+ fixed costKTotal costFCLqFigure 1Figure 2In the short run we will fix the amount of capital. The only way the firm can vary theamount of output it produces is to vary the labor that it hires. Under some reasonableconditions such as constant return to scale (to both variable and fixed factors), the isoquantswill be getting further apart. In other words, each time I have to hire more and more labor toproduce one more unit of output while holding K fixed. If I produce no output at all, I stillhave to pay the cost associated with the fixed amount of capital. As I start producing someoutput, my cost increases. (My total cost in this case is wages times the amount of labor plusthe fixed cost). Initially, my cost increases slowly but later I have to hire more and more laborto produce an additional unit of output, so my cost increases at an increasing rate as shown infigure 2.We can now define two notions: total cost and average cost. Total cost is shown infigure 2. Average cost is total cost divided by the units of output produced, or TC/q. In1Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 2terms of figure 2, average cost is the slope of the ray from the origin to the total cost curve.This would be the slope of the diagonal lines in Figure 2. When output is close to zero,average cost is really big (the slope is really steep). If my total cost is $10,000 and I produceone unit of output, my average cost is $10,000. If I only produce 1/2 unit of output, my average cost is $20,000, assuming the variable cost of ½ unit and 1 unit are the same. Asoutput increases, the slope decreases until it reaches a minimum. Beyond that minimum,average cost starts to rise again. So, my average cost curve might be expected to have somekind of a U-shape (see figure 3).Marginal cost. Marginal cost is the cost of producing one more unit of output. Marginalcost is the derivative of total cost with respect to output (q). As output increases, the slope ofmarginal cost gets steeper. Since capital is fixed (say capital is the amount of machines Ihave), the only way I can increase my output is by hiring more unit of labor. However, themore people I hire to work with the same number of machines, the less additional output Iwill be getting from each additional unit of labor. Eventually, I will run into some capacitylimitation and my output will be very difficult to increase.MCACTotal cost for the small factoryTotal cost for the large factoryqFigure 3Figure 4The marginal cost curve goes through the minimum of the average cost curve (see figure 3)because the minimum average cost is where the average cost is tangent to total cost (seefigure 2), and the slope of the tangent to total cost is marginal cost.For the intuition, think about bowling scores. You know that if you score less than youraverage, then you lower your average and if you score more than your average, then you raiseyou average. If your average stays the same, it must be because your score on the last gamewas the same as your average.Long run total cost and short run total cost. In the long run I can choose the amount ofthe fixed input, capital in this case. For example, I can choose between a small factory and alarge one. In terms of the graph, the total cost curve of a small factory will have a lower levelof fixed cost than the large factory. However, the total cost curve of the small factory willrise faster than the total cost curve of the larger factory (see figure 4).Which factory would I rather have? It would depend on how much I want to produce. IfI want to produce any amount up to where the short run total cost curves intersect, I wouldrather have the smaller factory because it produces it more cheaply. On the other hand, if Iwant to produce a large amount of output, then I want to have the larger factory because itproduces that level of output at a lower cost. If these two factories are my only alternatives,in the long run my total cost curve would look like the thick line in figure 4.If we have more alternatives in terms of size of factories (each alternative has a differenttotal cost curve), in the long run the cost of any particular level of output is going to be thecost associated with the cheapest means of producing that level of output. The long run totalcost curve will be the lower bound of all the short run total cost curves (see figure 5).2Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 3SRTCSRTC (1) SRTC LRTCAC (1)AC (3) AC (2)LRACqq11Figure 5Figure 6The LRTC curve is just the lower ‘envelope’ of all the SRTC curves. The LRTC curvedoes not have to start at the origin if there are fixed costs. For any particular set of fixedfactors, short run total cost is the minimum total cost over all of the factors that are variable.Long run total cost for a given level of output is the minimum of short run total cost overfixed factors of production given the level of output. And this is equal to the minimum (overfixed factors) of the minimum (over variable factors) of total cost given q.The question is in what order we are doing the minimization. We turned this into atwo-stage problem. My costs depend not only on the level of output but also on how much ofthe variable factors I hire and how much of the fixed factors I hire. We are defining short runcost as what you get when you minimize over the variable factors. And we are defining longrun cost as what you get when you minimize the short run cost over the fixed factor. What weend up with is a long run total cost obtained by minimizing costs over both fixed and variablefactors. The order of the minimization does not matter.Long run average cost and short run average cost. Figure 6 shows the average costcurves corresponding to the total cost curves in figure 5.short-run total cost=STC=wv xv (w, y, xf ) + wf x fshort-run average cost=SAC=c(w, y, xf ) / yshort-run average variable cost=SAVC=wv xv (w, y, xf ) / yshort-run average fixed cost=SAFC=wf x f / yshort-run marginal cost=SMC=∂c(w, y, x f ) / ∂ylong-run average cost=LAC=c(w, y) / ∂ylong-run marginal cost=LMC=∂c(w, y) / ∂yTo derive the long run and short run average cost curves, suppose we choose a certain level of output, say q1. At output level q1, long run total cost was obtained by choosing the minimum of all ways of producing q1. Output level q1 was produced at lowest cost by factory 1. At q1, the average total costs are the same in the short run and the long run. If factory 1 produces at any level of output different from q1, short run total costs are higher than long run total costs, and hence short run average costs are higher than long run average costs.We can repeat this analysis with factories 2 and 3. So the long run average cost curve is the envelope of the short run average cost curves, in the same way that my long run cost curve is the envelope of the short run total cost curves. Also, long run and short run average costs will be the same for the output level for which the particular factory is the least costly at producing the given level of output.3Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 4Note that the place where the SRAC curves and the LRAC curve are tangent is notnecessarily the minimum of each SRAC curve. When the LRAC curve is declining thetangency point occurs before the minimum of the SRAC curve and where the LRAC curve isincreasing, the tangency point occurs beyond the minimum of the SRAC curve. The onlypoint where the tangency point occurs at the minimum of a SRAC curve is at the minimum ofthe LRAC curve.This may sound confusing because we are saying that to produce a level of output q1, the best plant to use is plant 1. However, q1 is not the best level of output for that particular plant. Plant 1 could produce a higher level of output at a lower average cost. But if we want toproduce at that higher level of output, plant 1 would not be the best plant to use.We are not interested in the level of output that a plant produces most cheaply for itself.Instead, we are interested in how well that plant produces a particular level of output, relativeto other plants.If I want to produce 100 units of output and plant 1 produces the 100 units of output atthe lowest cost, I do not care if plant 1 can produce 110 units at a lower average cost. What Icare about is which plant produces 100 units in the cheapest way.A baseball analogy: I am interested in putting the best second baseman at second base.The fact that he may be a better third baseman does not interest me if I have a guy who playsthird base still better than he. The fact that you do third base best does not interest me if youhappen to be the best second base player I have and if I have a guy who can play third basebetter than you can.To summarize, what is important to you is not running a plant at its minimum averagecost. What is important to you is deciding what level of output you want to produce anddeciding how to produce that level of output in the cheapest way.How do we decide what level of output I want to produce? Suppose I can sell myoutput at price p per unit of output. If I sell q units, my revenue is pq. My profit is my revenueminus my cost. Graphically, my profit is the vertical difference between the revenue line andthe total cost curve (it does not matter if it is short run total cost or long run total cost) (seefigure 7).$TC Revenue (pq)LRMC LRACNegative profitsPPositive profitsqq*q*Figure 7Figure 8If I want to maximize my profit, I have to choose the point where the curves are thefurthest apart, that is, where the slopes are the same. Since the slope of the revenue line is theprice of output, and the slope of the total cost curve is marginal cost, I maximize my profitwhere price equals marginal cost (where output = q* in figure 7). If I produce less than that,price is greater than marginal cost and I can make more money by producing more. If Iproduce at a point where marginal cost is greater than price, then I can make more money byproducing less.4Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 5In figure 8, I maximize my profit if I produce at the level of output where the LRMC is equal to the price (at q*).So, I want to produce a level of output q*, and I want to produce it in the cheapest way. The factory associated with the SRAC curve in figure 8 is the factory that produces q* in the cheapest way. In this case, q* is at a point beyond the minimum for that factory.2．Examples:1). The short-run Cobb-Douglas cost functions. min w1x1 + w2 x2 s.t. x2 = k and y = x1a x12−a1−a⇒ SAC = w1( y / k) a + w2k / y1−aSMC=w1( y / k) a / a Proposition 1: Constant returns to scale. If the production function exhibits constant returns to scale, the cost function may be written as c(w, y)= y c(w,1).Proof: let x* be a cheapest way to produce one unit of output at prices w. Notice that yx* is feasible to produce y since the technology is constant returns to scale. Suppose it does not minimize cost; instead let x′ be the cost-minimizing bundle to produce y at w so wx′/y<wyx*/y. Then x′/y can produce 1 since the technology is constant returns to scale.Proposition 2: Marginal costs equal average costs at the point of minimum average costs.Proof: Let y* denote the point of minimum average cost, then to the left of y* averagecosts are declining so that for y≤y* d (c( y) / y) / dy ≤ 0 which implies c′( y) ≤ c( y) / y ∀y ≤ y * . A similar analysis shows that c′( y) ≥ c( y) / y ∀y ≥ y * .Proposition 3:limy→0cv( y) y= cv′ (0)2). CD cost curves1c( y) = Ky a+b1− a −bAC( y) = Ky a+bMC( y) = c′( y) =K1−a −by a+ba+bProposition 4: The long- and short run (average) cost curves are tangent.3. Factor prices and cost functionsProperties of the cost function (1) Non-decreasing in prices. If w′≥w, then c(w′, y) ≥c(w, y). (2) Homogeneous of degree 1 in w. c(tw, y)= t c(w, y) for t>0. (3) Concave in w. c(tw + (1− t)w′, y) ≥ tc(w, y) + (1− t)c(w′, y) ∀0 ≤ t ≤ 1(4) Continuous in w. c(w, y) is continuous as a function of w for w ? 0. (5) Shephard’s lemma. (the derivative property.) Let xi(w, y)be the firm’s conditional factor demand for input i. Then if the cost function is differentiable at (w, y), and wi>0 for i=1, …, n,5Microeconomic Theory: Lecturer. J. Ping FeiLecture 05- 6then xi (w, y) = ∂c(w, y) / ∂wi i = 1,L, n . Proof: Construct g(w)= c(w, y)−wx*, since is thecheapest way to produce y, ∂g(w)/∂wi=0. We can also prove it by the definition of c(w, y)= wx(w, y) or directly by the envelopetheorem. The concavity of the cost function is also a nice geometrical argument.4. The envelope theorem for constrained optimizationdM (a) = ∂L(x, a)da∂ax= x(a )=∂g ∂ax=x(a)−λ∂h ∂aApplications: Shephard’s lemma⇒∂c(w, ∂wiy)=xixi = xi ( w, y )=xi (w,y),marginal cost L = w1x1 + w2 x2 − λ[ f (x1, x2 ) − y] ∂c(w1, w2 , y) / ∂y = λ5. Comparative statics using the cost function1) The cost function is nondecreasing in factor prices⇔ Factor demand x(w,y) is nonnegative. 2) The cost function is homogeneous of degree 1 in w ⇔ x(w,y) is homogeneous of degree 0. 3) The cost function is concave in w has the following implications.a) the cross-price effects are symmetric. b) the own-price effects are nonpositive. c) dwdx≤06。

lecture 05 一致性假设检验

weighted least squares estimator (WLS). 因此，该式的OLS估计量被称为加权最小二乘估计量（WLS）
FGLS估计
• 如果h(x)不知道，应该怎么办？
• 下面的方法不是去猜，而是去估计一个函
数。
uˆi2 0 1x1 2 x2 ...k xk vi
• 这种方法的一个好处，预测值不能保证为正。
)
xi
2
x
2
如果有异方差呢？
• 上面的推导变为：
var(ˆ1)
xi x 2 var(ui ( xi x 2 )2
)
xi
2
x
2
• 看下面这个式子
xi x 2 var(ui ) ( xi x 2 )2
xi x 2uˆi2 ( xi x 2 )2
• 经过严格的证明，还真可以。
多元回归的情况
刻画，其中hi =h(x) 只依赖于可观测特征x • 把原方程的左右两边分别除以 h(x)：
yi h(x)
0
1 h(x)
1
x1 h(x)
...k
xk h(x)
ui h(x)
• 上面方程的残差：
var(ui*) var(
ui ) var(ui ) 2
h(x) h(x)
y* i
* 0
x* 1 i1
趋于零，故ˆ1的概率极限即1。
plimˆ1
1
n1 n1
xi1 x1 ui xi1 x1 2
1.
7
一个更弱的假定
• 要获得估计量的无偏性，我们假定零条件期望 – E(u|x1, x2,…,xk) = 0
• 而要获得估计量的一致性，我们可以使用更弱的假定：零期望和零相关性假定。

05_classes

Accessors
• • The getRadius() function is an example of an accessor It returns the value of something the class knows about By having a function to do this instead of a public member variable, we maintain control of the classes data We have the option to add other things to the function, or even completely redesign the class so the radius is stored
•
Access Control
Access Control
• • We cannot access the m_radius member of the class because it is private The compiler should have given you an error message explaining this Get used to reading the compiler's error messages very carefully!
Sphere Example
• This lecture we will be concerned with a single example: a class describing a sphere We are going to create a project in the IDE containing multiple files, to show how thisere Example

大学英语5E教程第一册Unit 1

5. He is about to embark on a new business venture. 他将要开始新的商业冒险活动。 Your own sentence: 制造商们马上要生产一种新产品。
The makers ____a_r_e_a_b_o_u_t_t_o___ launch a new product.
Joe turned around, pulled up his pant legs and shouted, “You tell me, Professor! You tell me!”
. Back
Next
A. Match the verbs (1–8) in the text to their meanings (a–h).
. Back
Next
C. Rearrange the following sentences according to the sequence of the story.
a. Joe pulled up his pant legs. b. The students were asked to identify each bird by looking at its legs. c. Joe stayed up all night studying for the test. d. Joe crumpled up his exam paper, and threw it onto the desk. e. The professor asked Joe his name.
1. memorize 2. stuff 3. announce 4. identify 5. reach 6. recover 7. cover 8. crumple

新编英语语法教程第05讲练习参考答案

Lecture 5EX.5A1. my father has a car2. the bull has horns3. the prisoners escaped4. her parents consented5. somebody released the prisoner .6. somebody assassinated the president7. a letter from the general /the general sent a letter8. the crowed felt sympathy9. a college for women10. a summer day, a day in summer11. the earth has a(rough)surface12. the absence lasted ten days13. a doctoral degree, a doctorate14. the bird made the nest15. the committee made a report16. a story told by the girl /the girl told a story17. the volcano erupted18. the victim had courage /the victim was courageous19. somebody punished the boy20. the critics received the play in a hostile mannerEX.5B1.The comedian performed, and he wads well received by a huge audience.这位喜剧演员的演出很受广大观众的欢迎。

2.She was thankful, for her litter girl had quickly recovered.她的小女孩很快康复，为此她非常感激。

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反映静电场本身的性质
思考题：在证明Gauss定理中，要求静电力必须与 r 2 成反比，那么在环路定理的证明中是否也要求静电力必须与 r 2 成反比？不一定! 如线性弹簧振子 f kr
静电场的环路定理: 在静电场中，电场强度沿任意闭合路径的环流恒为零。结论：静电场力是保守力，静电场是保守场。

A q0 Edr
ra P
q q0 q q1 q1 q2 q2 n n r 4 0 Pn rQn rP1 rQ1 rP 2 rQ 2
qq0 1 1 dr qo ( ) 4 0r 2 4 0 rP rQ rP q
电场强度沿某一方向的分量
（1）试证明等势面较密集的地方场强大，较稀疏的地方场强小。（2）两张 U 取值不同的等势面图上各处的场强大小可以比较吗？为什么？注意：上面的这些结论可以推广应用到军用等高线地图, 大气等压图等。
El
dU dl
电势沿该方向的变化率的负值
El
电场的法向 (n )分量
l ABC ADC
ADC
A
又 q0 E dl q0 E dl （静电场力做功与路径无关）

A q0 E dl 0
ABC
即静电场力移动电荷沿任一闭和路径所作的功为零。
A q0 E dl 0
q0 0

E dl 0
q 0 u 0 r u r u最小 q 0 u 0 r u r u最大
对称性以q为球心的同一球面上的点电势相等
2、电势叠加原理若场源为q1 、q2 qn的点电荷系，其场强满足叠加原理 E E1 E2 ....... En 场强电势
dU dU En E El dn dl
E
dl
b
El
E
dl
b
dU n E dn
等势面上各点的电势相等，则有
dU 0 d
dU 注意：是电势空间变化率的最大值，负号表示电场 dn 强度的方向与 n 的方向相反，是由高电势指向低电势。
E 0
等势面上任一点场强的切向分量为零。
Wa q0 E dl
a
电势能—焦耳（Ｊ）
1eV 1 .602 10 19 J
定义电势差：电场中a.b两点的电势之差（电压） b U ab U a U b E dl E dl E dl
a b
O

3. 电势零点可以任意选取，选择零点原则：场弱、变化不太剧烈；为什么？思考题: 1. 点电荷的势能零点是否可以选在电荷上？ 2. 无限大平面板的势能零点能否选在无穷远处？
势能零点可选在离平板有限距离的任意位置

P
X
dl 40 r
U P dU
40
2R
Z
方法二
其中则
Q
rb
r
Q
dr dl

cos dl dr
dA q0 Edr
P
r dr
E
q
q0
在电场中把试探电荷从P移至Q电场力所做的功 Q Q APQ F dl q0 E dl P P Q Q Q q0 E1 dl E2 dl En dl P P P
结论：即电场强度等于电势梯度的负值。
求电场强度E 的三种方法
利用电场强度叠加原理利用高斯定理利用电势与电场强度的微分关系
例利用场强与电势梯度的关系，计算均匀带电细圆环轴线上一点的场强。解 : u u ( x)
1 4 0 q R x
2 2
七电偶极层
设想一厚度均匀的曲面薄壳，两面带有符号相反的面电荷 e——电偶极层
2. 由点电荷电势公式，利用电势叠加原理计算
讨论:
1. 电势与场强一样是一个描述场本身性质的物理量，与试探电荷无关，是标量，电势叠加是标量叠加； 2. 电势
例1、求均匀带电圆环轴线上的电势分布。已知：R、q 解:方法一微元法
Y
dl
R

r
x
UP
：表示
P
点与无穷处电势差；
dU
dq 40 r
rQ
P到q1的距离
Q到q1的距离
力的做功与路径无关 ——保守力
每项均与路径无关，只与位置有关
Thu Sep 18 2014 14:47:18 GMT+0800
3. 任意有限大的带电体产生的电场可以将带电体无限分割成微元，每一个微元均为一点电荷 ——点电荷组结论：在任何电场中移动试探电荷时，电场力所做的功除了与电场本身有关外，只与试探电荷的大小及其起点、终点有关，与移动电荷所走过的路径无关静电场力做功与路径无关等价于静电场力沿任意闭合回路做功恒等于零.
R

q
40 r 2 q 40 R
dr
U
r

q 40 r
2
dr
r
在R处场强不连续，电势连续
0 dU E dl E cos dl
cos 0

+

a
正交

q 40 r
（2）等势面较密集的地方场强大，较稀疏的地方场强小。如何证明？
（3）电场线指向电势降落的方向。 dU E dl
a
，实际上是注意：电势能属于q0和电场构成的整个系统场源电荷和电荷 q0之间的相互作用能。
U ab
b
a
E dl
a、b两点的电势差等于将单位正电荷从a点移到b时，电场力所做的功。
将电荷q从ab电场力的功
五、电势的计算
1、点电荷电场中的电势如图 P点的场强为 E

Aab Wa Wb q0 E dl q0 (U a U b )
一般
所以
U U ( x, y , z )
Ex U ， x Ey U ， y
x
Ez
y
U z
z
E U
U ˆ U ˆ U ˆ i U j k z x y

U
U dU
(dU 0)
n
U ˆ ˆ ( U iˆ U ˆ j k) E E x iˆ E y ˆ j Ez k
Wa
Wb
b a
则ab电场力的功 Aab q0

E dl Wa Wb
若选取 b点为电势能零点
a
Wb 0
b Wa q0 E dl
结论：试验电荷qo在空间某处的电势能，在数值上就等于将qo从该处移至势能的零点电场力所作的功。
b Wa Wb q0 E dl
E在dl 方向上的分量El
U
El
n
dU El dl
结论：电场中任意一点的场强沿某方向的分量，等于这一点的电势沿该方向变化率的负值。课后思考题：
U dU
(dU 0)
U
El
n
E
dl
b
a

E
dl
b
E cos dl dU
El dl dU
高斯定理环路定理
静电场的两个基本性质：有源保守场
哪些力具有做功与路径无关这种性质？弹性力重力引力静电力保守力引入弹性势能引入重力势能引入引力势能引入静电势能可引入势函数
三、电势能
保守力的功=相应势能的减少所以静电力的功=静电势能增量的负值 a点电势能 b点电势能
b
a
试验电荷q0 处于
二、环路定理
q0沿任一闭合路径 ABCDA 一周电场力所作的功 A q0 E dl q0 E dl q0 E dl
l ABC CDA
C
E
D B
E dl E dl CDA ADC A q0 E dl q0 E dl q0 E dl
E1 dl E2 dl ....... En dl
P P P
P
P
1. 根据已知的场强分布，按定义计算
U P E dl P
U 1 U 2 ...... U n U i
i 1
n
点电荷系中某场点的电势等于各点电荷单独存在时在该点电势的代数和
dU dl dU dn
U dU
(dU 0)
U
El
n
dU n E dn
结论：电场中任一点电场强度，等于该点电势沿等势面法线方向变化率的负值。切向分量
E dU d

U
U dU
a

(dU 0)
n
a

En
又E与n 反平行 , 即 E En n
R
六等势面和电势梯度
rR
rR
1. 等势面等势面 : 静电场中电势相等的点组成的曲面规定：相邻等势面之间电势差相等。等势面的性质:
U E dl
P
0
R
O
rR
U E dl E dl
r R
P
（1）等势面与电场线处处正交
0
点电荷系的电势连续带电体的电势电势计算的两种方法：

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