lecture 6'- Design Theory for Relational Database-part 3 (Chapter 3)
工业设计专业英语Lesson 6 Italian design
精心整理Lesson6ItaliandesignTwentieth-centuryItaliandesignisonlyonefacetofthecultural,political,socialandeconomic storyofmodernItaly.Thestylish,mass-producedpiecesoffurniture,decorativehouseholdgoods ,electricalappliances,officeequipment,carsand,latterly,designerclothesandaccessories （thathaveearnedItalysuchakeypositionintheworldofcontemporarymaterialculture ）are,（inessence ）,amirrorof （thatcountry ’sbidformodernityandofitsstruggle,（ （例如，不像日本通过数年的仔细模仿来学习设计课程。
从一开始，意大利就决定找到一种独特的方式将艺术与工业结合起来。
Itowesthisachievementtoanumberoffactors,amongthemthesupportofsuchpowerfulandfar-sight edindustrialpatronsastheOlivetticompany;Italy’sdeep -seatedneedtoallydesignwiththedra matictransformationsinitspoliticalscene(andthesustaineddebateabouttheideologicalmeani ngindesignwhichthisbroughtwithit);thespecialnatureofItalianindustrialization,whichhasrespectedcrafttraditionswhileimplementingnewsystemsofmassproduction;andthecreativegen iusesofthesmallclusterofItalianarchitect-designerswhosenameshavebecomesynonymouswitht heconceptofmodernItaliandesign.意大利能取得这么大的成就有几个因素,其中例如Olivetti这样强大而富有远见的工业赞助公司的支持;意大利有很深的根基可以将设计与政治背景的戏剧性变化联合起来,(这将带来持续不变的关于设计观念的争论)意大利工业化的特殊性质是尊重传统手工业同时实施大批量生产的新系统.一大群富有创造力的天才意大利建筑设计师,他们的名字变成了现代意大利设计的代名词.“——“and “““”然而,计”更专业,更全面地理解这一定义的是批评家UmbertoEco,他在书中首次写道”一致性设计“.通过对比另外两种设计形式可以很好理解这一定义,他称为”匿名性设计”和”无意识性”设计,分别列举咖啡机和农具.Eco定义的”一致性设计”与另外两种设计相比,他说:”设计的目的是用明确的物品表达设计师的理念”他列举了汽车设计师巴蒂斯塔.皮尼法瑞德工作来说明这一现象. Ecoplacestheemphasisfirmlyontheself-consciousintentionsofthe“author”or“designer”. Histhesisisderivedfromtheso-called“auteur”theory,evolvedwithinthecontextoffilmcriti cism,whichdistinguishesbetweentheself-conscious“highculture"filmandthemorespontaneou s“massculture”filmwhichexpresses,unselfconsciously,thevaluesandaspirationsofmasssocietyasawhole.TheevolutioninItalyof（aself-conscious“highculture”designmovement）,whichcoexistsalongsidedesignwithinthemorebanalproductionandconsumpti onofgoods,iswhathasearnedItalyitsspecialplacewithintheworldofcontemporarymaterialcult ure.Inevitably,however,“identified”,“anonymous”and“non-conscious”typesofdesignh avenotevolvedcompletelyindependentlyofeachother,andtherearemanyoverlapsbetweenthem. 坚决地将重点放在“设计师”和“作者”的自我意识意图上，他的观点来自于所谓的“电影导演”理论，在电影批评理论之内演化，它把自我意识的“深厚文化”的电影与自发的“大众文化”的电（）uralpowerwithinthemodernindustrializedworld.Assuch,whilemodernItaliandesignoweditsori ginstospecificallyItalianconditions,anddisplayedvisualtraitsthathavebeendescribedaspa rticularly“Italian”incharacter(Italy’srichartisticheritageisfrequentlymentionedint hiscontext),itseffectsweregreateroutsideItaly.Itsspecialrolewastoprovideanationalimag ewithinthecontextofinternationaltradeandculture.ThusmostmodernItaliandesignwas(except intheveryearlystagesofitsevolution)“designforexport”,andassuchitsinfluenceonthegrea terpartofItaliansocietywas,andis,minimal.Fromtheearly1960sonwardsitsimpactwasfeltmost stronglyinthewealthyquartersofLondon,Paris,NewYorkandTokyo.Thus,whiletheproductionofItaliandesignisinextricablylinkedtotheeconomic,socialandculturalcontextofmodernItaly,i tsconsumptionisnot.然而，Eco忽视的没有指出的是，还有一些其他的特征也区别于这种意大利的特殊设计与广义上的设计。
Invited Lecture
8.4 ER-schemes
9 Conclusions and further research
We have introduced the use of translation schemes into database design theory. We have shown how they capture disparate notions such as information preservation and dependency preservation in a uniform way. We have shown how they relate to normal form theory and have stated what we think to be the Fundamental Problem of Database Design. Several resulting research problems have been explicitly stated in the paper. We have shown that the Embedded Implicational Dependencies are all needed, when we deal with stepwise re nements of database schemes speci ed by Functional and Inclusion Dependencies. As the material presented grew slowly while teaching database theory, its foundational and didactic merits should not be underestimated. Over the years our students of the advanced database theory course con rmed our view that traditional database design lacks coherence and that this approach makes many issues accessible to deeper understanding. Our approach via dependency preserving translation{re nements can be extended to a full edged design theory for Entity{Relationship design or, equivalently, for database schemes in ER-normal form, cf. MR92]. It is also the appropriate framework to compare transformations of ER-schemes and to address the Fundamental Problem of ER{Database Design. Translation schemes can also be used to deal with views and view updates, as views are special cases of translation schemes. The theory of complementary views from BS81] can be rephrased elegantly in this framework. It is connected with the notion of translation schemes invariant under a relation and implicit denability, Kol90]. Order invariant translation schemes play an important role in descriptive complexity theory, Daw93] and Mak94]. The theory of independent complementary views of KU84] exhibits some severe limitations on the applicability of BS81]. In spite of these limitations it seems worthwhile to explore the connection between independent views and transformation invariant for certain relations further. The latter two applications are currently being developed by the authors and their students and will be included in the full paper.
Lesson 6 On The Case Study Method Of Research And Teaching In Design
Simple, Powerful and free
Of course, the legal profession was fortunate in this respect, because there already existed an infrastructure by which cases were written to explain and interpret the principles used to reach legal judgment.
ENGLISH FOR INDUSTRIAL DESIGN
Simple, Powerful and free
Christopher Langdell changed that way of teaching when he arrived at Harvard Law School. He believed that, at its root, the art of practicing law involved understanding core principles and being able to apply those principles in different situations. Christopher Columbus Langdell (May 22, 1826 – July 6, 1906) was an American jurist and legal academic who was Dean of Harvard Law School from 1870 to 1895.
ENGLISH FOR INDUSTRIAL DESIGN
Simple, Powerful and free
学术综合英语1-5课课文及翻译
Presenting a speech（做演讲)Of all human creations，language may be the most remarkable。
Through language we share experience，formulate values，exchange ideas, transmit knowledge，and sustain culture。
Indeed，language is vital to think itself。
Contrary to popular belief]，language ｜does not simply mirror reality but also helps to create our sense of reality ［by giving meaning to events］。
在人类所有的创造中，语言也许是影响最为深远的.我们用语言来分享经验，传递价值观,交流思想，传播知识,传承文化。
事实上，对语言本身的思考也是至关重要的。
和通常所认为的不同的是，语言并不只是简单地反映现实，语言在具体描述事件的时候也在帮助我们建立对现实的感知。
——语序的调整。
Good speakers have respect for language and know how it works。
Words are the tools of a speaker’s craft。
They have special uses, just like the tools of any other profession。
As a speaker，you should be aware of the meaning of words and know how to use language accurately，clearly，vividly，and appropriately。
科技英语翻译1
► 2）通顺易懂 ► 译文的语言符合译语语法结构及表达习惯，容易为读者所理解和接受。
► A. When a person sees, smells, hears or touches something, then he is perceiving.
2. Cramped(狭窄的) conditions means that passengers’ legs cannot move around freely.
空间狭窄，旅客的两腿就不能自由活动。
3. All bodies are known to possess weight and occupy space.
忠实、通顺（普遍观点）
► 科技英语文章特点：(well-knit structure;tight logic;various styles)结构严谨，逻辑严密，文体多样
1. 科技翻译的标准：准确规范，通顺易懂，简洁明晰 1）准确规范
所谓准确，就是忠实地，不折不扣地传达原文的全部信息内容。 所谓规范，就是译文要符合所涉及的科学技或某个专业领域的专业语言表
实验结果等，而不是介绍这是这些结果，理论或现象是由谁发 明或发现的。
► In this section, a process description and a simplified process flowsheet are given for each DR process to illustrate the types of equipment used and to describe the flow of materials through the plant. The discussion does not mention all the variations of the flowsheet which may exist or the current status of particular plants. In the majority of the DR processes described in this section, natural gas is reformed in a catalyst bed with steam or gaseous reduction products from the reduction reactor. Partial oxidation processes which gasify liquid hydrocarbons, heavy residuals and coal are also discussed. The reformer and partial oxidation gasifier are interchangeable for several of the DR processes.
高教版新编研究生英语综合教程Unit 6 教参
Text AWord Study1.(1) dedicated (2) with a vengeance (3) agony (4) specialized (5) to the fullest (6) addiction (7) barely (8) navigate (9) amazing (10) slip away2.hospice; disease; patient; doctor; nurse; drug; medicine; ALS …Cloze1-5 B D A C D6-10 A B C D B11-15 C A C D A16-20 B C D B ATranslation:1.能够在家中逝去是人们选择临终关怀的主要原因之一。
但是病人和他们的家属起初并没有认识到这一点。
坎贝尔说: “很多人把临终关怀视为放弃治疗并且向疾病屈服。
”这正是为什么对于家人来说做出选择临终关怀这个决定有如此艰难的原因。
然而，一旦他们做了这个决定，大多数病人和家人很快就会理解其中的意义所在，即一支由社工、健康师（助理）、牧师和护士组成的专业人士通力合作为病人和家属提供身体上、感情上和精神上的支持与帮助。
2. America’s first hospice was founded in 1974, and the idea spread rapidly. Half of all Americans will now use hospice care at some point in their lives, and around 75% of deaths in American hospitals occur after an explicit decision not to intervene. In Europe, too, there has been a revolution in attitudes to care for people who are nearing the end of life, and in people’s willingness to broach the subject. Yet for all its successes, the hospice movement faces challenges that will far outstrip the resources now dedicated to palliative care, even in the richest countries. Hospices are generally associated with cancer, where after a certain stage life expectancy is short and fairly predictable. But treating people as “either temporarily i mmortal or dying”is the current habit.An important category of people, already huge in the rich world and soon to grow in developing countries, consists of elderly people who will never be well, but have no idea when they will die. There is no single answer: hospitals, nursing homes and family care will all play a role. Looking after the old is bound to be complicated; elderly people with several diseases can all too easily find themselves bounced from family doctor to health adviser to specialists in one field after another. But depending on their medical and political culture, different countries are tackling the problem in different ways.不必太过悲伤：记一位临终关怀护士的生活帮助即将离世的患者度过最后的时光会是怎样的感受呢？让我们借助吉尔·坎贝尔的所见经历这一切吧。
rfic-lecture6
2005-6
Institute of Microelectronics
VCO
z
Ring oscillator:
2005-6
Institute of Microelectronics
VCO
z
Due to its relative poor phase noise performance, ring oscillator is rarely used in RF systems.
– Frequency synthesis for wireless communications—reduce phase noise – Clock recovery for data communications—reduce timing jitter – Clock generation and distribution for microprocessors—reduce skew
2005-6
Institute of Microelectronics
LC Oscillator Topologies (Cont’d)
z
Current-steered LC oscillators: Complementary VCO
– Combining the NMOS and PMOS cross-coupled
z
Barkehausen’s criteria for oscillation:
2005-6
Institute of Microelectronics
Oscillators
z An
oscillator is a closed loop system with positive feedback z Two types of oscillators for PLLs
The Theory of Relativity and Its Implications
The Theory of Relativity and ItsImplicationsWhen we talk about the most significant scientific breakthroughs in history, one cannot leave out the theory of relativity. German physicist, Albert Einstein first published his theory of relativity in 1905 and further developed it in 1915, which completely transformed our understanding of space, time, matter, and energy. The theory of relativity is not just a scientific concept; its implications are far-reaching and have altered our perspectives on the universe, technology, and society.Relativity fundamentally demolished the classical understanding of physics. The previous paradigm of physics rested on Newton's laws of motion, which were believed to be absolute, independent of time, space, and the observer. Yet, Einstein argued that these laws are not fundamental and absolute but are only valid in a particular reference frame. He introduced two types of relativity.The first is the special relativity theory, which deals with objects moving at a constant speed relative to each other. It states that all physical laws are the same for all observers moving uniformly relative to one another. The speed of light, which is considered the most fundamental constant in the universe, plays a critical role in this theory. According to Einstein, nothing can travel faster than light, and the speed of light is constant, independent of the speed of the observer. This has profound implications for our understanding of time, space, mass, and energy.The second is the general relativity theory, which deals with objects under acceleration or in a gravitational field. According to this theory, gravity is not a force but is the result of the mass of one object curving the fabric of spacetime, causing other objects to move towards it. General relativity has revolutionized our scientific understanding of the universe. It predicted black holes, gravitational waves, and the big bang itself.The theory of relativity has been tested and verified repeatedly by experiments for over a century, from the bending of light during a solar eclipse to the atomic clocks on GPS satellites continually adjusted for faster time at higher altitude. Our understanding of the universe, from the behavior of galaxies to the fundamental nature of subatomic particles, depends on the theory of relativity.In addition to breakthroughs in the fields of astrophysics and quantum mechanics, the theory of relativity has had a remarkable impact on technology. GPS, for example, relies on the precise measurements of time and position differences for accurate navigation. The clocks on GPS satellites need to be continuously adjusted because time dilation occurs due to differences in the strength of the gravitational field. These adjustments are necessary to keep the GPS system working correctly. This is just one example of how the theory of relativity has transformed our daily lives.But perhaps the most significant implication of the theory of relativity is the transformation of our understanding of space and time. In classical physics, space and time were considered two separate entities, and time was believed to be absolute and universal. Einstein's theory of relativity, however, demonstrates that space and time are intertwined and that the flow of time depends on the observer's relative motion and proximity to gravity. This has profound implications for our social and cultural understanding of time.The theory of relativity went beyond reshaping our physical understanding of the universe; it also has deep implications for philosophy and human thought. The theory of relativity poses the question of the nature of reality, the nature of existence, and the limits of human understanding. The theory suggests that our perceptions of reality are shaped by our sensory experiences, and that the experience of time and space is subjective.In conclusion, the theory of relativity remains one of the most fascinating and profound scientific theories in history, with implications that extend far beyond the realm of physics. It has radically transformed our understanding of space, time, matter, and energy, revolutionized modern physics and technology, and challenged our fundamental beliefs about human existence. Einstein's theory of relativity remains an essentialscientific and philosophical work that will continue to inspire and provoke inquiry for generations to come.。
托福TPO1-30听力中Lecture部分的每个Lecture文章主旨大意和中心思想
childhood amnesia,rate of forgetting
中 parenting behaviors of birds
中
different types of residential architectures in the United States
中
the state of Florida,farmers moved south,great citric industry in Florida,the impact of landscapes on temperature
How you can successfully call attention to the service or
product you want to sell
DNA,chromosomes
MBWA--managing by wandering around
难 Opera,the golden age in French literature
Animal communication systems,human language
How whales became ocean dwellers
中 Where american food ingredients originally come from
nutrient cycle,the carbon cycle,the Phosphorus cycle
Lec 4 Art history
Lec 1 Art history
Lec 2 Environmental Science Lec 3 History Lec 4 Biology Lec 1 Astronomy Lec 2 Art history Lec 3 European history Lec 4 Biology
theory of relativity(相对论)
2013-9-13
Great ahievements of Albert Einstein
• In 1922, Einstein was awarded the 1921 Nobel Prize in Physics • In 1936, Einstein was awarded the Franklin Institute 's Franklin Medal • In 1999 Albert Einstein was named the Person of the Century
2013-9-13
• On Einstein introduced these new concept, most physicists, including relativity transformation between the founder of lorentz, feel hard to accept.
2013-9-13
• The old way of thinking of the obstacle, make this a new physical theory until generation only after for broad physicists are familiar with
2013-9-13
• The brief introduction of Albert Einstein • Great ahievements of Albert Einstein • The best well known achievement:Specia l relativity and General relativity • The members of our team
Lecture_PLL6
9
W. Rhee, Institute of Microelectronics, Tsinghua University
Synthesizer Design Trade-Offs
fBW ≈
ICP RKv 2π N
→
High N affects phase noise, spur, and settling time!!
4
W. Rhee, Institute of Microelectronics, Tsinghua University
Outline
• Introduction – Overview of frequency synthesis – Design trade-offs in PLL-based synthesizers • Fractional-N Frequency Synthesis – Basic concept – Spur reduction methods • ΔΣ Fractional-N Frequency Synthesizer Design – System design aspects – Circuit design aspects • Experimental Results • Fractional-N PLL for Various Applications • Future Challenges
20
W. Rhee, Institute of Microelectronics, Tsinghua University
Outline
• Introduction – Overview of frequency synthesis – Design trade-offs in PLL-based synthesizers • Fractional-N Frequency Synthesis – Basic concept – Spur reduction methods • ΔΣ Fractional-N Frequency Synthesizer Design – System design aspects – Circuit design aspects • Experimental Results • Fractional-N PLL for Various Applications • Future Challenges
Lecture 6
Stability, Asymptotic Stability, Instability
Lyapunov Theorem on Asymptotic Stability • Theorem 1: Consider a system described by
! = f ( x, t ), f (0, t ) = 0 " t x
Adaptive Control Applications
Example: Roll Dynamics
(Model Reference Adaptive Control)
• Uncertain Roll dynamics:
&= Lp p + Lδδail p
– p is roll rate, – δail is aileron position – Lp , Lδail are unknown damping, aileron effectiveness
B - = b0 , B + = B / b0
B+ = 1, B- = B
Conditions
• Two causality conditions:
deg Ac ³ 2 deg A - 1 deg Am - deg Bm ³ deg A - deg B = d0
• Compatibility conditions:
Ax + By = C
Diophantine Equation
• How to guarantee a solutions in polynomial case?
– A and B must be relatively prime!!
• Solving the Diophantine Equation
工业设计专业英语Lesson-6--Italian--design讲解学习
Lesson 6 Italian designTwentieth - century Italian design is only one facet of the cultural, political, social and economic story of modern Italy. The stylish, mass -produced pieces of furniture, decorative household goods, electrical appliances, office equipment, cars and, latterly, designer clothes and accessories （that have earned Italy such a key position in the world of contemporary material culture）are, （in essence）, a mirror of （that country’s bid for modernity and of its struggle, （through this century）, to establish itself as one of the modern industrial nations.二十世纪意大利设计仅仅是现代意大利文化、政治、社会和经济发展的一个方面。
具有现代风格的、批量生产的家具、具有装饰风格的家用物品、电器、办公设备、汽车和后来的设计师服装以及附属品为意大利设计在当代物质文化中赢得主要地位。
从实质上讲，通过本世纪的奋斗，（意大利设计师）作为这个国家要求和奋斗现代化的一面镜子，反映了意大利将确定成为现代工业国家的历程。
In achieving this ambition Italy has evolved a unique approach towards the practice, the aesthetic and the theory of design which depends, （only minimally）, upon models borrowed from elsewhere. As one of Italy’s leading critics and theorists of design, Gillo Dorfles, explained in 1986:“Here we have experienced the development of our own objects industrially made to native Italian design and therefore more original and more imaginative than those of other industrialized countries.Unlike Japan, for instance, which learned its lessons about design through years of careful imitation”. Italy was, from the outset, more determined to discover a new formula for its particular marriage between art and industry。
电动力学第六章相对论基础SpecialTheoryofrelativity
1907年迈克耳逊因创制精密光学仪器而获得诺贝尔物理学 奖
§6.2 狭义相对论的基本原理 洛仑兹变换
Fundamental Principles of The Special Theory of Relativity
Lorentz Transformation
一 基本原理（两个公理）
1 相对性原理（relativity principle）
r ct , S 2 0
(3) 若两个事件的空间距离超过了光波在时间t所传播的距 离，此时
r ct , S 2 0 ;
为了说明问题的方便，把三种间隔用一个三维时空图形表 示出来，事件用一个三维时空点P来表示。
ct
·P
45o
o
y
P点在 xy 面上的投影表示事件发生的
x
地点，P点的垂直坐标表示事件发生 的时刻 t 乘以c 。
意义：两事件的间隔与参照系的选择无关，是一个 不变量。它是光速不变原理的数学表示形式。
例：在系静止光源S发光，经M反
射后到S接收，设相对沿x轴正向
运动，计算时间和间隔。
l0
l0
t 2l0 / c
S
S vt
s2 c2 t2 t12 [ x2 x12 y2 y12 z2 z12 ] 4l02
t
1
v2 c2
静止坐标系测出的 时间，称为该物理 过程的固有时
在上看到物体以速度v运动。t> ，表示运动物体上发生的自然 过程比起静止物体的同样过程延缓了。物体运动速度越大，所观察 到的它的内部物理过程进行得越缓慢。这就是时间延缓效应。这种 效应是时空的基本属性引起的，与钟的具体结构无关。
时间的延缓
二 间隔不变性
1、事件
relativity
相对论英语:（Theory of relativity）是关于时空和引力的理论，主要由爱因斯坦 创立，依其研究对象的不同可分为狭义相对论和广义相对论。
相对论和量子力学的提出给物理学带来了革命性的变化，它们共同奠定了近代物理学的基础。
相对论极大的改变了人类对宇宙和自然的“常识性”观念，提出了“同时的相对性”、“四维时空”、“弯曲时空”等全新的概念。
不过近年来，人们对于物理理论的分类有了一种新的认识——以其理论是否是决定论的来划分经典与非经典的物理学，即“非经典的＝量子的”。
在这个意义下，相对论仍然是一种经典的理论。
狭义与广义相对论的分野 ：传统上，在爱因斯坦刚刚提出相对论的初期，人们以所讨论的问题是否涉及非惯性参考系来作为狭义与广义相对论分类的标志。
随着相对论理论的发展，这种分类方法越来越显出其缺点——参考系是跟观察者有关的，以这样一个相对的物理对象来划分物理理论，被认为较不能反映问题的本质。
目前一般认为，狭义与广义相对论的区别在于所讨论的问题是否涉及引力（弯曲时空），即狭义相对论只涉及那些没有引力作用或者引力作用可以忽略的问题，而广义相对论则是讨论有引力作用时的物理学的。
用相对论的语言来说，就是狭义相对论的背景时空是平直的，即四维平凡流型配以闵氏度规，其曲率张量为零，又称闵可夫斯基时空即‘闵氏时空’；而广义相对论的背景时空则是弯曲的，其曲率张量不为零。
狭义相对论 ：爱因斯坦 在他1905年的论文《论动体的电动力学》中介绍了其狭义相对论。
狭义相对论建立在如下的两个基本公设上：·狭义相对性原理（狭义协变性原理）：一切的惯性参考系都是平权的，即物理规律的形式在任何的惯性参考系中是相同的。
这意味着物理规律对于一位静止在实验室里的观察者和一个相对于实验室高速匀速运动着的电子是相同的。
·光速不变原理 ：真空中的光速在任何参考系下是恒定不变的,这用几何语言可以表为光子在时空中的世界线总是类光的。
Lecture6
《高等量子力学》第6讲8）Casimir 效应基态能（真空能、零点能）有无观测效应？考虑量子电磁场的能量。
电磁场是各种频率k ω（能量k ω ）的简谐振动的集合，空间单位体积内电磁场的总能量是33012(2)2k n d k E n ωπ∞=⎛⎫=+ ⎪⎝⎭∑⎰ ， 其中k ck ω=，k 是波数，n 是能量为k ω 的光子的数目，2是独立偏振的方向。
真空是无激发的态，0n =，真空能量33(2)k d kE ωπ=⎰ 为无穷大。
一般计算时将它作为激发的本底扣除掉。
问题是它本身是否有可观测效应？设在电磁场中放入两块平行的板，面积为2, L L 足够大，距离为a L <<。
边界条件使得在a 方向的波数受到限制，z n k aπ=，在横方向由于L 很大，无限制。
于是在两板之间的体积2L a 内的真空能量为()222()2n d kE a L c π==⎰， 用到02222z z ndk dk a πππ∞∞-∞==∑⎰⎰。
放入两块平行板前后真空能量的变化为()220200()()()2n d k E a E a E a L c dn π∞=⎛∆=-=- ⎝∑⎰⎰这个变化使得两板之间每单位面积上的力 21()()E a F a L a∂∆=-∂。
注意()E a 与0()E a 都是发散的（真空分散），但()E a ∆是有限的。
经过计算（见一般量子力学教科书，例如苏汝铿和张永德的书），有24()240c F a a π=- 。
这个插入平行板后由于真空能量的变化（涨落）导致的吸引力以及与a 的关系于1958年被实验观测到。
这是真空能量的变化导致的可观测效应。
9）Heisenberg 绘景中的力学量时间演化忽略下标H ，由Heisenberg 绘景中的运动方程，有ˆˆ11ˆˆˆˆˆˆ, , , ,da da a H i a a H i a dt i dt i ωω+++⎡⎤⎡⎤==-==⎣⎦⎣⎦ 解为 ˆˆˆˆ()(0), ()(0),i ti t at a e at a e ωω-++== 注意： ˆˆˆˆ()()(0)(0)at a t a a ++= 使得粒子数表象的基矢n 与时间无关。
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先用A C 先用 后用B C 后用
先用C D 先用 后用DE C 后用 在用CE A 在用
该全a行元组r3是R‘的元组 因此r3在R中。 而该r3=t正是ti连接结果。
出现全a行， 出现全 行 为无损分解! 为无损分解
1.4 Chase检测有效性分析二 不出现全 行) 检测有效性分析二( 检测有效性分析二 不出现全a行
Three important things to remember:
The natural join is associative结合律 and commutative交换律.
⊆包含？ ⊆ As a consequence, πS1(R) ⊳⊲πS2(R) ⊳⊲πSk(R) =R when the FD’s in F hold for R if and only if: every tuple in the join is also in R. The chase test for a lossless join It is just an organized way to see whether a tuple t in πS1(R) ⊳⊲πS2(R) ⊳⊲πSk(R) can
1.3 Chase检测有效性分析一 出现全 行) 检测有效性分析一( 检测有效性分析一 出现全a行
例18-5: R(ABCDE), F: A C,B C,C D,DE C,CE A ρ={R1(AD),R2(AB),R3(BE),R4(CDE),R5(AE)} 是无损分解? A B C D E Ai R1 a1 b12 b13 a4 b15 R2 a1 a2 b23 b24 b25 R3 b31 a2 b33 b34 a5 R4 b41 b42 a3 a4 a5 R5 a1 b52 b53 b54 a5 R1 R2 R3 R4 R5 R1 R2 R3 R4 R5 A a1 a1 b31 b41 a1 A a1 a1 a1 a1 a1 B b12 a2 a2 b42 b52 B b12 a2 a2 b42 b52 C b13 b13 b13 a3 b13 C a3 a3 a3 a3 a3 D a4 b24 b34 a4 b54 D a4 a4 a4 a4 a4 E b15 b25 a5 a5 a5 E b15 b25 a5 a5 a5
３ Multivalued Dependencies (MVD)
Multivalued Dependencies(MVD) is an assertion that two attributes or sets of attributes are independent of one another Every FD implies a corresponding MVD (Later, we will see why.) However, there are some situations involving independence of attributes sets that cannot be explained as FD’s
重新连接时，新关系中一定包含了元组: (a,b,c,d), 但它不在R’中！
2 无损、且保持函数依赖的分解 无损、
2.1 极小函数依赖集 min 极小函数依赖集F
(最小基本集)
定义 函数依赖仅有 X (1)右部属性‘精简’: 单属性 无X A 使F-{X (2)函数依赖‘精简’: 无冗余 (3)左部属性‘精简’: 左部属性数少
应用举例
例10-9 (无损且保持依赖的到3NF的分解)
算法10.6-2(保持依赖分解为 保持依赖分解为3NF) 算法 保持依赖分解为
1.步 步
2.步 步
3.步 依赖的到3NF的分解 的分解) 例10-9(无损、且保持依赖的到 无损 的分解
ZS,PCS为两侯选键 为两侯选键
DABASE SYSTEMS
(Computer Science 2008, Classes 1-6)
Lecture 6:
(Chapter 3)
Design Theory for Relational Database
(Part 3)
-Design of RDB Schemas (2)
Lecturer: Lingqiu Zeng
1 Chase检测方式的有效性
1.1 The Chase Test for Lossless Join （复习）
If we project R onto the relations of decomposition, then we can recover R by taking the natural join of all the relations? namely πS1(R) ⊳⊲πS2(R) ⊳⊲πSk(R) =R ?
A relation R1 of multivalued dependency
There exist redundancy in its relation.
4 Fourth Normal Form(4NF)
4.1 Definition
The redundancy in Example 3.28 caused by MVD’s can be eliminated if we use dependencies in a new decomposition algorithm for relations A MVD A1A2An B1B2Bm for a relation R is nontrivial if
3.10
Explanation
Explanation: the MVD in the relation of example 3.28
假设的 3.10
3.10
3.10
不存在任何函数依赖关系
3.2 Definition of MVD
.
A’s B’s
说法2
对Ａ’s每一个值对应的一组元组
说法1
C’s=R-A’s-B’s
R1 R2 R3 A a a2 a3 A a a a3 B b b b3 B b b b3 C c1 c c C c1 c c D d1 d2 d D d1 d1 d
R的一个实例 的一个实例:R’:设 的一个实例 设 不同d 产生t1 元组r1, 产生 的R元组 且使 不同 元组 且使d1不同 产生t2 元组r2 产生 的R元组 元组 产生t3 元组r3 产生 的R元组 元组 产生t4 元组r4 不同于a和 产生 的R元组 且使 元组 且使a3,b3不同于 和b 不同于
到3NF的保持依赖的分解
算法10.6-2 (任何模式R都可保持依赖地分解为一组3NF.) 定理10.6-1 (算法10.6-2产生一个保持依赖的到3NF的分解)
到3NF的无损且保持依赖的分解
算法10.6-3
定理10.6-2 (算法10.6-3产生一个无损且保持依赖的到3NF的分解)
(算法 算法10.6-2+任一后选键 任一后选键) 算法 任一后选键
3.10
3.10 3.28
Another example of MVD:
R1(课程C, 教师T, 参考书B)
It is in BCNF.
教师T, 参考书B
It two MVD’s:
课程C 课程C
It can be represented with the following relation of MVD
---Chase检验不成立时一定不是无损连接！ 检验不成立时一定不是无损连接！ 检验不成立时一定不是无损连接
图例说明： 图例说明 设t=(a,b,c,d)， ， 由t1=(a,b),t2=(b,g), t3=(c,d)连接而成， 下说明t不在R中？
例 3.24: R(A,B,C,D) FD: B AD, 划分为:R1(A,B),R2 (B,C), R3(C,D) ，均无非平凡函数依赖！
A, A单属性 单属性 A}与F等价 与 等价
等价, 无X A 使F-{X A}U{Z A}与 F等价 Z⊂X 与 等价 ⊂
定理10.2-2 (任何函数依赖集都与一最小函数依赖集等价) 证明(构造性证明) 存在但不一定唯一!
定理10.2-2的构造性证明 的构造性证明 定理
2.2 到3NF的分解 的分解
假设:R(A1,A2, …,An),F 分解为ρ={R1,R2,…,Rn} Ri(Ui) i=1,2,…,n
A1 A2 … Aj … An R1 R2 … Rk … Rk … … Mij
Aj∈Ui ∈ 否则
一般判别方法
正确写出左图18-7是关键 反复使用F中函数依赖对判定矩阵进行变换 ρ是无损分解⇔出现全a行 (证略,图例分析1，图例分析2) 例18-5(对应算法步骤介绍)
Go to example 3.32
Example 3.28: A relation schema of MVD
Go to example 3.30 Go to 4.1 4NF Go to example 3.29
.
3.28
p.118 two paragraphs (example 3.33… 3.10 Fig.3.29….)
be proved, using the FD’s in F, also to be a tuple in R. »反包含？
Any tuple t in R is surely in πS1(R) ⊳⊲πS2(R) ⊳⊲πSk(R)
1.2 无损分解的判别方法 (复习)
(The chase test for a lossless join, please also see Example 3.22)
说法3 说法
A’s t a1 v a1 u a1
B’s b1 b1 b2
Others c1 c2 c2