In P.M. Wognum and I.F.C. Smith (Eds.), Knowledge Based Systems, Special Issue on Models an
计算机组成原理-白中英-第5版共55页
24、勇气很有理由被当作人类德性之 首，因 为这种 德性保 证了所 有其余 的德性 。--温 斯顿． 丘吉尔 。 25、梯子的梯阶从来不是用来搁脚的 ，它只 是让人 们的脚 放上一 段时间 ，以便 让别一 只脚能 够再往 上登。
谢谢你的阅读
❖ 知识就是财富 ❖ 丰富你的人生
71、既然我已经踏上这条道路，那么，任何东西都不应妨碍我沿着这条路走下去。——康德 72、家庭成为快乐的种子在外也不致成为障碍物但在旅行之际却是夜间的伴侣。——西塞罗 73、坚持意志伟大的事业需要始终不渝的精神。——伏尔泰 74、路漫漫其修道远，吾将上下而求索。——屈原 75、内外相应，言行相称。——韩非
49编号博士研究生英语精读-翻译及原文（中科院）
第1课知识的悖论The Paradox of KnowledgeThe greatest achievement of humankind in its long evolution from ancient hominoid ancestors to its present status is the acquisition and accumulation of a vast body of knowledge about itself, the world, and the universe. The products of this knowledge are all those things that, in the aggregate, we call "civilization," including language, science, literature, art, all the physical mechanisms, instruments, and structures we use, and the physical infrastructures on which society relies. Most of us assume that in modern society knowledge of all kinds is continually increasing and the aggregation of new information into the corpus of our social or collective knowledge is steadily reducing the area of ignorance about ourselves, the world, and the universe. But continuing reminders of the numerous areas of our present ignorance invite a critical analysis of this assumption.In the popular view, intellectual evolution is similar to, although much more rapid than, somatic evolution. Biological evolution is often described by the statement that "ontogeny recapitulates phylogeny"--meaning that the individual embryo, in its development from a fertilized ovum into a human baby, passes through successive stages in which it resembles ancestral forms of the human species. The popular view is that humankind has progressed from a state of innocent ignorance, comparable to that of an infant, and gradually has acquired more and more knowledge, much as a child learns in passing through the several grades of the educational system. Implicit in this view is an assumption that phylogeny resembles ontogeny, so that there will ultimately be a stage in which the accumulation of knowledge is essentially complete, at least in specific fields, as if society had graduated with all the advanced degrees that signify mastery of important subjects.Such views have, in fact, been expressed by some eminent scientists. In 1894 the great American physicist Albert Michelson said in a talk at the University of Chicago:While it is never safe to affirm that the future of Physical Science has no marvels in store even more astonishing than those of the past, it seems probable that most of the grand underlying principles have been firmly established and that further advances are to be sought chiefly in the rigorous application of these principles to all the phenomena which come under our notice .... The future truths of Physical Science ate to be looked for in the sixth place of decimals.In the century since Michelson's talk, scientists have discovered much more than the refinement of measurements in the sixth decimal place, and none is willing to make a similar statement today. However, many still cling to the notion that such astate of knowledge remains a possibility to be attained sooner or later. Stephen Hawking, the great English scientist, in his immensely popular book A Brief History of Time (1988), concludes with the speculation that we may "discover a complete theory" that "would be the ultimate triumph of human reason--for then we would know the mind of God." Paul Davies, an Australian physicist, echoes that view by suggesting that the human mind may be able to grasp some of the secrets encompassed by the title of his book The Mind of God (1992). Other contemporary scientists write of "theories of everything," meaning theories that explain all observable physical phenomena, and Nobel Laureate Steven Weinberg, one of the founders of the current standard model of physical theory, writes of his Dreams of a Final Theory (1992).Despite the eminence and obvious yearning of these and many other contemporary scientists, there is nothing in the history of science to suggest that any addition of data or theories to the body of scientific knowledge will ever provide answers to all questions in any field. On the contrary, the history of science indicates that increasing knowledge brings awareness of new areas of ignorance and of new questions to be answered.Astronomy is the most ancient of the sciences, and its development is a model of other fields of knowledge. People have been observing the stars and other celestial bodies since the dawn of recorded history. As early as 3000 B.C. the Babylonians recognized a number of the constellations. In the sixth century B.C., Pythagoras proposed the notion of a spherical Earth and of a universe with objects in it chat moved in accordance with natural laws. Later Greek philosophers taught that the sky was a hollow globe surrounding the Earth, that it was supported on an axis running through the Earth, and chat stars were inlaid on its inner surface, which rotated westward daily. In the second century A.D., Ptolemy propounded a theory of a geocentric (Earth-centered) universe in which the sun, planets, and stars moved in circular orbits of cycles and epicycles around the Earth, although the Earth was not at the precise center of these orbits. While somewhat awkward, the Ptolemaic system could produce reasonably reliable predictions of planetary positions, which were, however, good for only a few years and which developed substantial discrepancies from actual observations over a long period of time. Nevertheless, since there was no evidence then apparent to astronomers that the Earth itself moves, the Ptolemaic system remained unchallenged for more than 13 centuries.In the sixteenth century Nocolaus Copernicus, who is said to have mastered all the knowledge of his day in mathematics, astronomy, medicine, and theology, became dissatisfied with the Ptolemaic system. He found that a heliocentric system was bothmathematically possible and aesthetically more pleasing, and wrote a full exposition of his hypothesis, which was not published until 1543, shortly after his death. Early in the seventeenth century, Johannes Kepler became imperial mathematician of the Holy Roman Empire upon the death of Tycho Brahe, and he acquired a collection of meticulous naked-eye observations of the positions of celestial bodies chat had been made by Brahe. On the basis of these data, Kepler calculated that both Ptolemy and Copernicus were in error in assuming chat planets traveled in circular orbits, and in 1609 he published a book demonstrating mathematically chat the planets travel around the sun in elliptical orbits. Kepler's laws of planetary motion are still regarded as basically valid.In the first decade of the seventeenth century Galileo Galilei learned of the invention of the telescope and began to build such instruments, becoming the first person to use a telescope for astronomical observations, and thus discovering craters on the moon, phases of Venus, and the satellites of Jupiter. His observations convinced him of the validity of the Copernican system and resulted in the well-known conflict between Galileo and church authorities. In January 1642 Galileo died, and in December of chat year Isaac Newton was born. Modern science derives largely from the work of these two men.Newton's contributions to science are numerous. He laid the foundations for modem physical optics, formulated the basic laws of motion and the law of universal gravitation, and devised the infinitesimal calculus. Newton's laws of motion and gravitation are still used for calculations of such matters as trajectories of spacecraft and satellites and orbits of planets. In 1846, relying on such calculations as a guide to observation, astronomers discovered the planet Neptune.While calculations based on Newton's laws are accurate, they are dismayingly complex when three or more bodies are involved. In 1915, Einstein announced his theory of general relativity, which led to a set of differential equations for planetary orbits identical to those based on Newtonian calculations, except for those relating to the planet Mercury. The elliptical orbit of Mercury rotates through the years, but so slowly that the change of position is less than one minute of arc each century. The equations of general relativity precisely accounted for this precession; Newtonian equations did not.Einstein's equations also explained the red shift in the light from distant stars and the deflection of starlight as it passed near the sun. However, Einstein assumed chat the universe was static, and, in order to permit a meaningful solution to the equations of relativity, in 1917 he added another term, called a "cosmological constant," to the equations. Although the existence and significance of a cosmological constant is stillbeing debated, Einstein later declared chat this was a major mistake, as Edwin Hubble established in the 1920s chat the universe is expanding and galaxies are receding from one another at a speed proportionate to their distance.Another important development in astronomy grew out of Newton's experimentation in optics, beginning with his demonstration chat sunlight could be broken up by a prism into a spectrum of different colors, which led to the science of spectroscopy. In the twentieth century, spectroscopy was applied to astronomy to gun information about the chemical and physical condition of celestial bodies chat was not disclosed by visual observation. In the 1920s, precise photographic photometry was introduced to astronomy and quantitative spectrochemical analysis became common. Also during the 1920s, scientists like Heisenberg, de Broglie, Schrodinger, and Dirac developed quantum mechanics, a branch of physics dealing with subatomic particles of matter and quanta of energy. Astronomers began to recognize that the properties of celestial bodies, including planets, could be well understood only in terms of physics, and the field began to be referred to as "astrophysics."These developments created an explosive expansion in our knowledge of astronomy. During the first five thousand years or more of observing the heavens, observation was confined to the narrow band of visible light. In the last half of this century astronomical observations have been made across the spectrum of electromagnetic radiation, including radio waves, infrared, ultraviolet, X-rays, and gamma rays, and from satellites beyond the atmosphere. It is no exaggeration to say chat since the end of World War II more astronomical data have been gathered than during all of the thousands of years of preceding human history.However, despite all improvements in instrumentation, increasing sophistication of analysis and calculation augmented by the massive power of computers, and the huge aggregation of data, or knowledge, we still cannot predict future movements of planets and other elements of even the solar system with a high degree of certainty. Ivars Peterson, a highly trained science writer and an editor of Science News, writes in his book Newton's Clock (1993) that a surprisingly subtle chaos pervades the solar system. He states:In one way or another the problem of the solar system's stability has fascinated and tormented asrtonomers and mathematicians for more than 200 years. Somewhat to the embarrassment of contemporary experts, it remains one of the most perplexing, unsolved issues in celestial mechanics. Each step toward resolving this and related questions has only exposed additional uncertainties and even deeper mysteries.Similar problems pervade astronomy. The two major theories of cosmology,general relativity and quantum mechanics, cannot be stated in the same mathematical language, and thus are inconsistent with one another, as the Ptolemaic and Copernican theories were in the sixteenth century, although both contemporary theories continue to be used, but for different calculations. Oxford mathematician Roger Penrose, in The Emperors New Mind (1989), contends that this inconsistency requires a change in quantum theory to provide a new theory he calls "correct quantum gravity."Furthermore, the observations astronomers make with new technologies disclose a total mass in the universe that is less than about 10 percent of the total mass that mathematical calculations require the universe to contain on the basis of its observed rate of expansion. If the universe contains no more mass than we have been able to observe directly, then according to all current theories it should have expanded in the past, and be expanding now, much more rapidly than the rate actually observed. It is therefore believed that 90 percent or more of the mass in the universe is some sort of "dark matter" that has not yet been observed and the nature of which is unknown. Current theories favor either WIMPs (weakly interacting massive particles) or MACHOs (massive compact halo objects). Other similar mysteries abound and increase in number as our ability to observe improves.The progress of biological and life sciences has been similar to that of the physical sciences, except that it has occurred several centuries later. The theory of biological evolution first came to the attention of scientists with the publication of Darwin's Origin of Species in 1859. But Darwin lacked any explanation of the causes of variation and inheritance of characteristics. These were provided by Gregor Mendel, who laid the mathematical foundation of genetics with the publication of papers in 1865 and 1866.Medicine, according to Lewis Thomas, is the youngest science, having become truly scientific only in the 1930s. Recent and ongoing research has created uncertainty about even such basic concepts as when and how life begins and when death occurs, and we are spending billions in an attempt to learn how much it may be possible to know about human genetics. Modern medicine has demonstrably improved both our life expectancies and our health, and further improvements continue to be made as research progresses. But new questions arise even more rapidly than our research resources grow, as the host of problems related to the Human Genome Project illustrates.From even such an abbreviated and incomplete survey of science as this, it appears that increasing knowledge does not result in a commensurate decrease in ignorance, but, on the contrary, exposes new lacunae in our comprehension and confronts us with unforeseen questions disclosing areas of ignorance of which wewere not previously aware.Thus the concept of science as an expanding body of knowledge that will eventually encompass or dispel all significant areas of ignorance is an illusion. Scientists and philosophers are now observing that it is naive to regard science as a process that begins with observations that are organized into theories and are then subsequently tested by experiments. The late Karl Popper, a leading philosopher of science, wrote in The Growth of Scientific Knowledge (1960) chat science starts from problems, not from observations, and chat every worthwhile new theory raises new problems. Thus there is no danger that science will come to an end because it has completed its task, clanks to the "infinity of our ignorance."At least since Thomas Kuhn published The Structure of Scientific Revolutions (1962), it has been generally recognized that observations are the result of theories (called paradigms by Kuhn and other philosophers), for without theories of relevance and irrelevance there would be no basis for determining what observations to make. Since no one can know everything, to be fully informed on any subject (a claim sometimes made by those in authority) is simply to reach a judgment that additional data are not important enough to be worth the trouble of securing or considering.To carry the analysis another step, it must be recognized that theories are the result of questions and questions are the product of perceived ignorance. Thus it is chat ignorance gives rise to inquiry chat produces knowledge, which, in turn, discloses new areas of ignorance. This is the paradox of knowledge: As knowledge increases so does ignorance, and ignorance may increase more than its related knowledge.My own metaphor to illustrate the relationship of knowledge and ignorance is based on a line from Matthew Arnold: "For we are here as on a darkling plain...." The dark chat surrounds us, chat, indeed, envelops our world, is ignorance. Knowledge is the illumination shed by whatever candles (or more technologically advanced light sources) we can provide. As we light more and more figurative candles, the area of illumination enlarges; but the area beyond illumination increases geometrically. We know chat there is much we don't know; but we cannot know how much there is chat we don't know. Thus knowledge is finite, but ignorance is infinite, and the finite cannot ever encompass the infinite.This is a revised version of an article originally published in COSMOS 1994. Copyright 1995 by Lee Loevinger.Lee Loevinger is a Washington lawyer and former assistant attorney general of the United States who writes frequently for scientific c publications. He hasparticipated for many years as a member, co-chair, or liaison with the National Conference of Lawyers and Scientists, and he is a founder and former chair of the Science and Technology Section of the American Bar Association. Office address: Hogan and Hartson, 555 Thirteenth St. NW, Washington, DC 20004.人类从古类人猿进化到当前的状态这个长久的进化过程中的最大成就是有关于人类自身、世界以及宇宙众多知识的获得和积聚。
HKU Syllabus
Evans, D. S., A. Hagiu and R. Schmalensee, 2006, Invisible Engines: How Software Platforms Drive Innovation and Transform Industries, Cambridge, MA: The MIT Press. (hereafter referred to as “IE book”)PDF of book accessible from MIT Press website at:/catalog/item/default.asp?ttype=2&tid=11447(I obviously don’t mind if you also decide to buy it!/Invisible-Engines-Platforms-Innovation-Industries/dp/0262550687/ref=sr_1_1?ie=UTF8&s=books&qid=1243847610&sr=8-1 )Session 1: Network effects introductionMy slides should be enough to give you a solid background on network effects and some important applicationsIf you are curious about the first early papers in economics on network effects (direct), the following article provides a good survey (note it was written in 1994, long before the “two-sided market economics” took off):Katz, Michael, and Carl Shapiro, “Systems Competition and Network Effects.” Journal of Economic Perspectives 8 (Spring 1994): 93–115.Chapter 3 in the IE book also contains some background on network effects and economies of scale, especially on how they apply to software platforms and related industries.Another reference book on network effects and the information economy:Shapiro, Carl, and Hal Varian. Information Rules. Cambridge, MA, Harvard Business School Press, 1998.Session 2: Two-Sided Pricing Principles and Videogames case studyGeneral principles on two-sided pricing (technical economics papers):∙Armstrong, M., 2006, "Competition in Two-Sided Markets," Rand Journal of Economics, 37(3), 669-691.∙Hagiu, A. “Two-Sided Platforms: Product Variety and Pricing Structures,” Journal of Economics and Management Strategy, Vol 18(4), 2009. Available at: /ahagiu/Two%20Sided%20Platform%20Pricing%20JEMS%20accepted%2003072009.pdf∙Parker G. and Van Alstyne M. (2005) ``Two-Sided Network Effects: A Theory of Information Product Design,” Management Science, Vol. 51, No. 10.∙Rochet, J.-C., and J. Tirole (2003) “Platform Competition in Two-Sided Markets,”Journal of the European Economic Association, Vol. 1 (4), 990-1029.Chapters 5 (videogames) and 10 in the IE book contain in-depth analyses of pricing strategies by videogames platforms, comparison between videogames and PCs and general principles of two-sided pricing (especially as they apply to software platforms)If you are very interested in videogames, the entire detailed story of Microsoft’s entry (including their unsuccessful efforts to replicate the PC model) is covered in:Takahashi, Dean Opening the Xbox. Roseville, Calif.: Prima Publishing, 2002.Session 3: Bundling and commitmentSome references on bundling:∙Chapter 11 in the IE book for discussion of bundling issues relevant to software platforms ∙George J. Stigler, “United States v. Loew’s Inc.: A Note on Block Booking,” Supreme Court Review 152 (1963): 152–157. This article is referred to in the chapter above: it aims to explain why movie studios sell bundles of movies to theaters.∙Bakos, Yannis, and Erik Brynjolfsson. “Bundling Information Goods: Pricing, Profits, and Efficiency.” Management Science 45 (December 1999): 1613–1630 ∙Schmalensee, Richard. “Commodity Bundling by Single-Product Monopolies.” Journal of Law and Economics 25, no. 1 (April 1982): 67–71.Commitment in two-sided markets:∙Hagiu, A., 2006 "Pricing and Commitment by Two-Sided Platforms," Rand Journal of Economics, 37 (3), 720-737.Earlier version available at: /ahagiu/pricing%20and%20commitment%20by%20two-sided%20platforms%20revised%204%20Rand%20format%202222006.pdf(I strongly recommend the slides used in class instead of this paper: the model in theslides is more intuitive and closer to applications…)Session 4: MSP dynamicsCritical mass:∙Evans, D.S. and R. Schmalensee (2009) “Failure To Launch: Critical Mass in Platform Businesses,” working paper available at:/sol3/papers.cfm?abstract_id=1353502Divide and Conquer:∙Jullien, B. (2008) “Competing in Network Industries: Divide and Conquer,” working paper, IDEI Toulouse, available at: http://idei.fr/doc/by/jullien/julliendc0701.pdf∙Caillaud, B. and B. Jullien, 2003, “Chicken and Egg: Competition Among Intermediation Service Providers,” Rand Journal of Economics, 34(2), 309-328.Staging Two-Sided Platforms:∙Eisenmann, T. and A. Hagiu (2007) “Staging Two-Sided Platforms,” HBS note 808-004.∙Eisenmann, T. and A. Hagiu (2007) “A Staged Solution to the Catch-22,” Forethought column, Harvard Business Review, 25-26, November.Session 5: MSP governanceAkerlof, G. (1970) “The Market for Lemons: Quality Uncertainty and the Market Mechanism,”The Quarterly Journal of Economics, 84(3), pp. 488-500.Boudreau, K. and A. Hagiu (2009) “Platform Rules: Multi-Sided Platforms As Regulators,” inAnnabelle Gawer (ed), Platforms, Markets and Innovation, Cheltenham, UK and Northampton,MA, US: Edward Elgar, 2009.Chapter available in article format at: /sol3/papers.cfm?abstract_id=1269966Hagiu, A. (2009) “Quality vs. Quantity and Exclusion by Two-Sided Platforms,” Harvard Business School working paper. Available at:/ahagiu/Quality%20vs.%20quantity%20and%20exclusion%20by%20TSPs%2004062009.pdfSession 6Hagiu, A. and B. Jullien (2008) “Why Do Intermediaries Divert Search?”, Harvard BusinessSchool working paper 08-010. Available at:/ahagiu/Hagiu%20Jullien%20revision%2004202010.pdfLizzeri, A. (1999) “Information Revelation and Certification Intermediaries,” Rand Journal of Economics, Vol. 30(2), pp. 214-231.Baye, M. R. and J. Morgan (2001) “Information Gatekeepers on the Internet and the Competitiveness of Homogeneous Product Markets,” American Economic Review, Vol. 91(3),pp. 454-474.Session 7IE book, chapter 9, in particular pages 256-259.Note on Multi-Sided Platforms – HBS noteHagiu, A. (2007) "Merchant or Two-Sided Platform?" Review of Network Economics, Vol. 6(2),115-133. Available at: /ahagiu/Merchants%20vs%20Two-Sided%20Platforms%20for%20RNE%2006302007%20final.pdfSession 8: IP intermediariesTwo economic articles on related topics (only if you are really curious/interested in the economics of IP)Farrell, J. and C. Shapiro (2008) “How Strong Are Weak Patents,” American Economic Review, 98:4, 1347–1369Schmalensee, R. (2009) ”Standard-Setting, Innovation Specialists and Competition Policy,” /sol3/papers.cfm?abstract_id=1219784Session 10: What makes two-sided markets special?On open vs. closed two-sided platforms and social efficiency:/sol3/papers.cfm?abstract_id=980755Some background on Net Neutrality debate: /wiki/Network_neutralityOn “animal strategies” in TSM:/ahagiu/EA%20animal%20strategies%20in%20TSM%2007232008.p dfOn strategic spinoffs:/ahagiu/20090726%20-%20Exclusivity%20and%20Control.pdf。
自然语言处理
自然语言处理2002．11．09中国科学院计算技术研究所1.综述.1.1. 绪论.1.1.1.背景,目标.1.1.1.1. 研究自然语言的动力1．语言是思维的裁体，是人际交流的重要工具。
在人类历史上以语言文字形式记载和流传的知识占到知识总量的80％以上。
就计算机的应用而言，据统计用于数学计算的仅占10％，用于过程控制的不到5％，其余85％左右都是用于语言文字的信息处理。
在这样的社会需求下，自然语言理解作为语言信息处理技术的一个高层次的重要方向，一直是人工智能界所关注的核心课题之一。
2．由于创造和使用自然语言是人类高度智能的表现，因此对自然语言理解的研究也有助于揭开人类智能的奥秘，深化我们对语言能力和思维本质的认识。
.1.1.1.2. 什么是计算语言学计算语言学（Computational Linguistics）指的是这样一门学科，它通过建立形式化的数学模型，来分析、处理自然语言，并在计算机上用程序来实现分析和处理的过程，从而达到以机器来模拟人的部分乃至全部语言能力的目的。
计算语言学（Computational Linguistics）有时也叫计量语言学（Quantitative Linguistics）, 数理语言学（Mathematical Linguistics）, 自然语言理解（Natural Language Understanding）, 自然语言处理（Natural Language Processing）, 人类语言技术（Human Language Technology）。
.1.1.1.3. 图灵测验在人工智能界，或者语言信息处理领域中，人们普遍认为可以采用著名的1950年描述的图灵试验(Turing Test )来判断计算机是否“理解”了某种自然语言。
.1.1.1.3.1.Turing模仿游戏(Imitation Game)●场景：男性被试、女性被试、观察者，3者在3个不同的房间，房间号分别为X, Y, O●规则：观察者用电传打字机与被试们通信，男性被试欺骗观察者、女性被试帮助观察者。
中英文在线翻译
中英文在线翻译The three flows of a supply chain 供应链的三种“流”Supply chain management (SCM) is concerned with the integration, coordination and control of the flow of material, information and finances in supply chains.供应链管理（SCM）涉及到对供应链中材料流、信息流和资金流所进行的整合、协调和控制。
SCM can be divided into three main flows:❝The product flow or materials flow includes moving goods from supplier to consumer as well as dealing with customer service needs.❝The information flow includes order information and delivery status.❝The financial flow includes payments schedules, credit terms and additional arrangements.SCM分为三个主要的流：❝产品流或材料流包括包括商品从供应商向客户的移动，也包括处理客户的服务需求。
❝信息流包括订单信息及交付状况。
❝金流包括付款时间安排表，赊账条款以及追加安排❝The Bullwhip Effect“牛鞭效应”❝The bullwhip effect (or whiplash effect) is an observed phenomenon in forecast-driven distribution channels. It refers to a trend of larger and larger swings in inventory in response to changes in demand. The concept first appeared in Jay Forrester's Industrial Dynamics (1961) and thus it is also known as the Forrester effect.Since the oscillating demand upstream a supply chain is reminiscent of a cracking whip, it became known as the bullwhip effect.❝“牛鞭效应”或“鞭抽效应”是在预测驱动型流通渠道中的一种已观察到的现象。
英文文献及翻译
word文档 可自由复制编辑 ABSTRACT An impact crusher with a rotor and one or more impact members interconnected to form an adjustable impact member system，a first impact member being mounted pivotally around a first horizontal axis by way of at least one drive means，on the second horizontal axis of which a further impact member，pivotal by way of at least one drive means，is provided，in which context the horizontal axis pivotally supporting the impact member is provided in the region of that end of the first impact member which is remote from the horizontal axis and the second impact member comprises one or more levers. IMPACT CRUSHER FIELD OF THE INVENTION Our present invention relates to an impact crusher of the type in which a rotor is Provided with crushing elements which cooperate with impact members which cooperate to form a crushing gap and to an impact member assembly suitable for use with such a rotor. Moro Particularly the invention relates to an impact crusher comprising a rotor and two or more impact members interconnected to form an adjustable impact member system，a first impact member being mounted pivotally around a first horizontal axis by way of at least one drive means，and having a second horizontal axis on which a second impact member，pivotal by way of at least one drive means，15 provided. BACKGROUND OF THE INVENTION An impact crusher for crushing material of various consistencies is known for example from DE 23 31 729 Al in which the impact plates are interconnected in articulated manner to form a coherent composite pivotal impact member，each of the interconnected impact plates deriving adjustable support individually from the housing. The impact plates may have impact surfaces which are at angles to one another or arc stepped along the path of the material as it 15 entrained from the inlet side of the machine. The principles of such machines have also been developed in the Chemical Engineers Handbook，Perry and Chilton，5th edition，McGraw Hill Book Company， New York，1973，at Chapters，pages 19 ff. This known impact crusher，just like impact other crushers of the same genus，suffers from the substantial drawback that the upper impact member，provided downstream of the machine inlet yields outwardly due to foreign objects which cannot be crushed entering the machine，so that the crushing gap between the rotor and the lower impact member is decreased to such an extent，due to the upper impact member pivoting outwardly，that a risk arises of foreign objects getting wedged between the rotor and the impact member,leading to possible damage to the rotor and/or the impact member，so that the continued operability of the installation can no longer be ensured. OBJECTS OF THE INVENTION It is the principal object of the present invention to provide an improved impact crusher such that the damage which can be caused by the entry of a noncrushable foreign object can be minimized. Another object of the invention is to provide an improved impact crusher which is free from the drawbacks of earlier devices or apparatuses of this type and particularly the drawbacks mentioned above. Still another object of this invention is to provide improved impact assembly for a rotor-type crusher or breaker whereby drawbacks which could have resulted in down time can be avoided. SUMMARY OF THE INVENTION These objects are attained，in accordance with the invention in an impact crusher of the type in which a rotor and two or more impact members are provided along the path of the crusher members of the rotor to form an adjustable impact assembly. A first impact member is pivotally mounted at a first word文档 可自由复制编辑
Prospect-了解国内外科技产出的最新动态
（中国基础研究的份额只占总R&D6%，远低于发达国家的20%等）/statistics/seind08
/
1995–2005 （20年的后10年， 美国，日本增长平缓，亚洲成2倍增长，其中根据最新汤姆森路透报道 中国SCI自然科学论文跃入 前5位。但是引用仍然有待进一步发展空间）while Asia's output doubled (figure O-18 ). China moved to fifth place in total article output, and a number of other Asian economies, including South Korea, Singapore, and Taiwan, registered steep publications increases, suggesting improving basic scientific infrastructure. But a broad citation measure (citations received adjusted for the volume of articles available for citation) indicates a more measured pace of increasing article quality for many Asian locations.
人力资源（教育）与知识密集性经济的对应关系 Human capital development responds to incentives of the knowledge-intensive economy
In international comparison, the United States has a larger proportion of the working-age population with a higher education degree (39%) than most other countries (figure O45 ). Only the Russian Federation (55%), Israel (45%), and Canada (45%) have higher percentages for this indicator 资料显示知识密集性经济 的发展与高等教育关系密切。 如美国等在职人口中受高等 教育比例较高（39%）， 苏 联（55%），以色列（45 ％）， 加拿大（45％）
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
In: P.M. Wognum and I.F.C. Smith (Eds.), Knowledge Based Systems, Special Issue on Models and Techniquesfor Reuse of Designs 1996
Redesign and reuse in compositional knowledge-based systemsFrances M T Brazier, Pieter H G van Langen, Jan Treur and Niek J E WijngaardsArtificial Intelligence Group, Department of Mathematics and Computer Science,Vrije Universiteit Amsterdam, De Boelelaan 1081a, 1081 HV Amsterdam, The NetherlandsEmail: {frances, langen, treur, niek}@cs.vu.nl
This paper introduces a task model for redesign of compositional knowledge-based systems based on a generictask model of design. A generic task model of design provides an abstract description of a design task and ageneric structure which can be refined for design tasks in specific domains of application. A generic task modelof design, shown to incorporate redesign, is presented and refined to a task model for redesign of compositionalknowledge-based systems. The applicability of this task model will be illustrated for the redesign of a diagnosticknowledge-based system.
Keywords: design, redesign, reuse, knowledge-based systems, compositional architectures, generic taskmodels
INTRODUCTIONKnowledge of alternative (models of) systems and system components is often the basis forredesign of an existing system; for example, a software system or hardware system. Thisholds in particular for the redesign of compositional knowledge-based systems. Existing taskmodels, varying from generic to more specific, instantiated or non-instantiated, are candidatecomponents for replacement, refinement, specialisation or instantiation of components of anexisting knowledge-based system. Such components are also often used during initial design.Redesign is, in essence, an inherent part of most design processes: new requirements or newdomain knowledge often influence design processes. Design is a complex task, in whichextensive knowledge of the domain of application is essential. The domain knowledge fordesign is broad: it includes not only knowledge of characteristics of the design object domainand knowledge of existing (partial) design object descriptions and sets of requirements, butalso knowledge of design strategies to guide the design process. As design necessarily entails(re)use of such design knowledge, a thorough analysis of a design process is of importancefor understanding the extent to which existing design domain knowledge can be effectivelyemployed and how.2Frances M T Brazier, Pieter H G van Langen, Jan Treur, and Niek J E WijngaardsIn principle, design is a process in which, given existing design object descriptions and a setof requirements (and their qualifications), an object is designed on the basis of knowledge ofthe design object domain and knowledge of design strategies. Qualifications of requirementsdenote preferences between (sets of) requirements, indicating the importance of (sets of)requirements for the design process. Some requirements may be qualified as hard, others assoft, for example. During a design process, individual requirements may be (temporarily)translated (by deductive or heuristic reasoning) to a set of more specific requirements.Fulfilment of the specific requirements implies the fulfilment of the more broadly specifiedrequirements from which they were derived. Reasoning about requirements is also needed tomanage conflicting requirements, and to determine which requirements should be imposed(and which should be retracted) at a given point in the design process1.
A generic task model of design, in which reasoning about requirements and theirqualifications and reasoning about design object descriptions are distinguished, has beenproposed by Brazier, Langen, Ruttkay, and Treur2. This model is based on a logical analysisof design processes3 and on analyses of existing applications4,5. It provides not only anabstract description of a design process comparable to a design model6 or a design theory7,but also a generic structure which can be refined for specific design tasks in differentdomains of application. Refinement of the generic task model of design, by specialisation andinstantiation, involves the specification of knowledge about applicable requirements and theirqualifications, about the design object domain, and about design strategies.
Reuse of task models is essential to a compositional approach to system design. It provides abasis for reuse at more specific levels: reuse of more specific task models and reuse ofspecific (instantiated and non-instantiated) components designed to perform specificsubtasks. A description of this process for the design of an elevator configuration, based onthe documentation provided by Yost8, can be found in Brazier, Langen, Treur, Wijngaards,and Willems9. Notions similar to our notion of generic task model10 can be found inliterature, such as generic tasks11,12 and interpretation models13.