Note on the sums of powers of consecutive $q$-integers

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书香飘逸四方的英语作文

书香飘逸四方的英语作文

The fragrance of books is a metaphor for the influence and allure of literature and knowledge.It is often said that the scent of books can travel far and wide,touching the lives of people across different cultures and societies.Here is an English composition that captures the essence of this concept:In the tranquility of a library,the air is filled with a unique scent.Its not the smell of paper or ink,but rather the ethereal fragrance of knowledge and wisdom that has been distilled through the ages.This is the scent of books,a fragrance that has the power to travel beyond the confines of walls and borders,reaching out to the hearts and minds of people everywhere.The allure of books is not limited to the physical possession of them.It is the ideas and stories they contain that truly captivate us.A wellwritten novel can transport us to a different time and place,allowing us to experience the lives of characters who may be vastly different from ourselves.A collection of poems can stir our emotions,making us feel a range of sentiments from joy to sorrow.A scientific textbook can open our eyes to the wonders of the universe,sparking a lifelong passion for learning.The fragrance of books is not just a sensory experience it is a journey of the soul.It is the journey of discovery,where each page turn reveals new insights and perspectives.It is the journey of growth,where we learn from the experiences of others and apply those lessons to our own lives.It is the journey of connection,where we find common ground with people from all walks of life through the shared experience of reading.In todays digital age,the traditional book may seem to be losing its relevance.However, the essence of what a book represents the transmission of knowledge and the power of storytelling remains as vital as ever.Ebooks and online articles may lack the physical presence of a printed page,but they carry the same potential to inspire,educate,and transform.The scent of books is not confined to the pages of a single volume.It permeates the halls of academia,the quiet corners of coffee shops,and the bustling markets of city streets.It is in the conversations that books inspire,the debates they provoke,and the dreams they nurture.It is in the very fabric of society,influencing the way we think,feel,and interact with the world around us.As we continue to explore the vast expanse of human knowledge,let us not forget the power of the written word.The fragrance of books is a testament to the enduring impactof literature on our lives.It is a reminder that,no matter how far we travel or how much time passes,the essence of a good book will always remain with us,guiding us,inspiring us,and enriching our existence.In conclusion,the fragrance of books is a universal phenomenon that transcends cultural and geographical boundaries.It is a reminder of the timeless value of literature and the profound influence it has on our lives.As we continue to read,learn,and grow,let us carry the scent of books with us,spreading its influence to every corner of the world.。

希尔伯特的23个数学问题

希尔伯特的23个数学问题

BULLETIN(New Series)OF THEAMERICAN MATHEMATICAL SOCIETYVolume37,Number4,Pages407–436S0273-0979(00)00881-8Article electronically published on June26,2000MATHEMATICAL PROBLEMSDAVID HILBERTLecture delivered before the International Congress of Mathematicians at Paris in1900.Who of us would not be glad to lift the veil behind which the future lies hidden;to cast a glance at the next advances of our science and at the secrets of its development during future centuries?What particular goals will there be toward which the leading mathematical spirits of coming generations will strive?What new methods and new facts in the wide and richfield of mathematical thought will the new centuries disclose?History teaches the continuity of the development of science.We know that every age has its own problems,which the following age either solves or casts aside as profitless and replaces by new ones.If we would obtain an idea of the probable development of mathematical knowledge in the immediate future,we must let the unsettled questions pass before our minds and look over the problems which the science of to-day sets and whose solution we expect from the future.To such a review of problems the present day,lying at the meeting of the centuries,seems to me well adapted.For the close of a great epoch not only invites us to look back into the past but also directs our thoughts to the unknown future.The deep significance of certain problems for the advance of mathematical science in general and the important rˆo le which they play in the work of the individual investigator are not to be denied.As long as a branch of science offers an abundance of problems,so long is it alive;a lack of problems foreshadows extinction or the cessation of independent development.Just as every human undertaking pursues certain objects,so also mathematical research requires its problems.It is by the solution of problems that the investigator tests the temper of his steel;hefinds new methods and new outlooks,and gains a wider and freer horizon.It is difficult and often impossible to judge the value of a problem correctly in advance;for thefinal award depends upon the grain which science obtains from the problem.Nevertheless we can ask whether there are general criteria which mark a good mathematical problem.An old French mathematician said:“A mathematical theory is not to be considered complete until you have made it so clear that you can explain it to thefirst man whom you meet on the street.”This clearness and ease of comprehension,here insisted on for a mathematical theory,I should still more demand for a mathematical problem if it is to be perfect;for what is clear and easily comprehended attracts,the complicated repels us.Moreover a mathematical problem should be difficult in order to entice us,yet not completely inaccessible,lest it mock at our efforts.It should be to us a guide408DA VID HILBERTpost on the mazy paths to hidden truths,and ultimately a reminder of our pleasure in the successful solution.The mathematicians of past centuries were accustomed to devote themselves to the solution of difficult particular problems with passionate zeal.They knew the value of difficult problems.I remind you only of the“problem of the line of quickest descent,”proposed by John Bernoulli.Experience teaches,explains Bernoulli in the public announcement of this problem,that lofty minds are led to strive for the advance of science by nothing more than by laying before them difficult and at the same time useful problems,and he therefore hopes to earn the thanks of the mathematical world by following the example of men like Mersenne,Pascal, Fermat,Viviani and others and laying before the distinguished analysts of his time a problem by which,as a touchstone,they may test the value of their methods and measure their strength.The calculus of variations owes its origin to this problem of Bernoulli and to similar problems.Fermat had asserted,as is well known,that the diophantine equationx n+y n=z n(x,y and z integers)is unsolvable—except in certain self-evident cases.The attempt to prove this impossibility offers a striking example of the inspiring effect which such a very special and apparently unimportant problem may have upon science.For Kummer,incited by Fermat’s problem,was led to the introduction of ideal numbers and to the discovery of the law of the unique decomposition of the numbers of a circularfield into ideal prime factors—a law which to-day in its generalization to any algebraicfield by Dedekind and Kronecker,stands at the center of the modern theory of numbers and whose significance extends far beyond the boundaries of number theory into the realm of algebra and the theory of functions.To speak of a very different region of research,I remind you of the problem of three bodies.The fruitful methods and the far-reaching principles which Poincar´e has brought into celestial mechanics and which are to-day recognized and applied in practical astronomy are due to the circumstance that he undertook to treat anew that difficult problem and to approach nearer a solution.The two last mentioned problems—that of Fermat and the problem of the three bodies—seem to us almost like opposite poles—the former a free invention of pure reason,belonging to the region of abstract number theory,the latter forced upon us by astronomy and necessary to an understanding of the simplest fundamental phenomena of nature.But it often happens also that the same special problemfinds application in the most unlike branches of mathematical knowledge.So,for example,the problem of the shortest line plays a chief and historically important part in the foundations of geometry,in the theory of curved lines and surfaces,in mechanics and in the calculus of variations.And how convincingly has F.Klein,in his work on the icosahedron,pictured the significance which attaches to the problem of the regular polyhedra in elementary geometry,in group theory,in the theory of equations and in that of linear differential equations.In order to throw light on the importance of certain problems,I may also refer to Weierstrass,who spoke of it as his happy fortune that he found at the outset of his scientific career a problem so important as Jacobi’s problem of inversion on which to work.MATHEMATICAL PROBLEMS409 Having now recalled to mind the general importance of problems in mathematics, let us turn to the question from what sources this science derives its problems. Surely thefirst and oldest problems in every branch of mathematics spring from experience and are suggested by the world of external phenomena.Even the rules of calculation with integers must have been discovered in this fashion in a lower stage of human civilization,just as the child of to-day learns the application of these laws by empirical methods.The same is true of thefirst problems of geometry, the problems bequeathed us by antiquity,such as the duplication of the cube, the squaring of the circle;also the oldest problems in the theory of the solution of numerical equations,in the theory of curves and the differential and integral calculus,in the calculus of variations,the theory of Fourier series and the theory of potential—to say noting of the further abundance of problems properly belonging to mechanics,astronomy and physics.But,in the further development of a branch of mathematics,the human mind, encouraged by the success of its solutions,becomes conscious of its independence. It evolves from itself alone,often without appreciable influence from without,by means of logical combination,generalization,specialization,by separating and col-lecting ideas in fortunate ways,new and fruitful problems,and appears then itself as the real questioner.Thus arose the problem of prime numbers and the other problems of number theory,Galois’s theory of equations,the theory of algebraic invariants,the theory of abelian and automorphic functions;indeed almost all the nicer questions of modern arithmetic and function theory arise in this way.In the meantime,while the creative power of pure reason is at work,the outer world again comes into play,forces upon us new questions from actual experience, opens up new branches of mathematics,and while we seek to conquer these new fields of knowledge for the realm of pure thought,we oftenfind the answers to old unsolved problems and thus at the same time advance most successfully the old theories.And it seems to me that the numerous and surprising analogies and that apparently prearranged harmony which the mathematician so often perceives in the questions,methods and ideas of the various branches of his science,have their origin in this ever-recurring interplay between thought and experience.It remains to discuss briefly what general requirements may be justly laid down for the solution of a mathematical problem.I should sayfirst of all,this:that it shall be possible to establish the correctness of the solution by means of afinite number of steps based upon afinite number of hypotheses which are implied in the statement of the problem and which must always be exactly formulated.This requirement of logical deduction by means of afinite number of processes is sim-ply the requirement of rigor in reasoning.Indeed the requirement of rigor,which has become proverbial in mathematics,corresponds to a universal philosophical necessity of our understanding;and,on the other hand,only by satisfying this requirement do the thought content and the suggestiveness of the problem attain their full effect.A new problem,especially when it comes from the world of outer experience,is like a young twig,which thrives and bears fruit only when it is grafted carefully and in accordance with strict horticultural rules upon the old stem,the established achievements of our mathematical science.Besides it is an error to believe that rigor in the proof is the enemy of simplic-ity.On the contrary wefind it confirmed by numerous examples that the rigorous method is at the same time the simpler and the more easily comprehended.The410DA VID HILBERTvery effort for rigor forces us tofind out simpler methods of proof.It also fre-quently leads the way to methods which are more capable of development than the old methods of less rigor.Thus the theory of algebraic curves experienced a considerable simplification and attained greater unity by means of the more rigor-ous function-theoretical methods and the consistent introduction of transcendental devices.Further,the proof that the power series permits the application of the four elementary arithmetical operations a well as the term by term differentiation and integration,and the recognition of the utility of the power series depending upon this proof contributed materially to the simplification of all analysis,particularly of the theory of elimination and the theory of differential equations,and also of the existence proofs demanded in those theories.But the most striking example for my statement is the calculus of variations.The treatment of thefirst and second variations of definite integrals required in part extremely complicated calculations, and the processes applied by the old mathematicians had not the needful rigor. Weierstrass showed us the way to a new and sure foundation of the calculus of variations.By the examples of the simple and double integral I will show briefly,at the close of my lecture,how this way leads at once to a surprising simplification of the calculus of variations.For in the demonstration of the necessary and sufficient criteria for the occurrence of a maximum and minimum,the calculation of the sec-ond variation and in part,indeed,the wearisome reasoning connected with thefirst variation may be completely dispensed with—to say nothing of the advance which is involved in the removal of the restriction to variations for which the differential coefficients of the function vary but slightly.While insisting on rigor in the proof as a requirement for a perfect solution of a problem,I should like,on the other hand,to oppose the opinion that only the concepts of analysis,or even those of arithmetic alone,are susceptible of a fully rigorous treatment.This opinion,occasionally advocated by eminent men,I con-sider entirely erroneous.Such a one-sided interpretation of the requirement of rigor would soon lead to the ignoring of all concepts arising from geometry,mechanics and physics,to a stoppage of theflow of new material from the outside world,and finally,indeed,as a last consequence,to the rejection of the ideas of the continuum and of the irrational number.But what an important nerve,vital to mathematical science,would be cut by the extirpation of geometry and mathematical physics! On the contrary I think that wherever,from the side of the theory of knowledge or in geometry,or from the theories of natural or physical science,mathematical ideas come up,the problem arises for mathematical science to investigate the principles underlying these ideas and so to establish them upon a simple and complete system of axioms,that the exactness of the new ideas and their applicability to deduction shall be in no respect inferior to those of the old arithmetical concepts.To new concepts correspond,necessarily,new signs.These we choose in such a way that they remind us of the phenomena which were the occasion for the formation of the new concepts.So the geometricalfigures are signs or mnemonic symbols of space intuition and are used as such by all mathematicians.Who does not always use along with the double inequality a>b>c the picture of three points following one another on a straight line as the geometrical picture of the idea “between”?Who does not make use of drawings of segments and rectangles enclosed in one another,when it is required to prove with perfect rigor a difficult theorem on the continuity of functions or the existence of points of condensation?Who could dispense with thefigure of the triangle,the circle with its center,or with the crossMATHEMATICAL PROBLEMS411 of three perpendicular axes?Or who would give up the representation of the vector field,or the picture of a family of curves or surfaces with its envelope which plays so important a part in differential geometry,in the theory of differential equations, in the foundation of the calculus of variations and in other purely mathematical sciences?The arithmetical symbols are written diagrams and the geometricalfigures are graphic formulas;and no mathematician could spare these graphic formulas,any more than in calculation the insertion and removal of parentheses or the use of other analytical signs.The use of geometrical signs as a means of strict proof presupposes the exact knowledge and complete mastery of the axioms which underlie thosefigures;and in order that these geometricalfigures may be incorporated in the general treasure of mathematical signs,there is necessary a rigorous axiomatic investigation of their conceptual content.Just as in adding two numbers,one must place the digits under each other in the right order,so that only the rules of calculation,i.e.,the axioms of arithmetic,determine the correct use of the digits,so the use of geometrical signs is determined by the axioms of geometrical concepts and their combinations.The agreement between geometrical and arithmetical thought is shown also in that we do not habitually follow the chain of reasoning back to the axioms in arithmetical,any more than in geometrical discussions.On the contrary we ap-ply,especially infirst attacking a problem,a rapid,unconscious,not absolutely sure combination,trusting to a certain arithmetical feeling for the behavior of the arithmetical symbols,which we could dispense with as little in arithmetic as with the geometrical imagination in geometry.As an example of an arithmetical theory operating rigorously with geometrical ideas and signs,I may mention Minkowski’s work,Die Geometrie der Zahlen.1Some remarks upon the difficulties which mathematical problems may offer,and the means of surmounting them,may be in place here.If we do not succeed in solving a mathematical problem,the reason frequently consists in our failure to recognize the more general standpoint from which the problem before us appears only as a single link in a chain of related problems. Afterfinding this standpoint,not only is this problem frequently more accessible to our investigation,but at the same time we come into possession of a method which is applicable also to related problems.The introduction of complex paths of integration by Cauchy and of the notion of the ideals in number theory by Kummer may serve as examples.This way forfinding general methods is certainly the most practicable and the most certain;for he who seeks for methods without having a definite problem in mind seeks for the most part in vain.In dealing with mathematical problems,specialization plays,as I believe,a still more important part than generalization.Perhaps in most cases where we seek in vain the answer to a question,the cause of the failure lies in the fact that problems simpler and easier than the one in hand have been either not at all or incompletely solved.All depends,then,onfinding out these easier problems,and on solving them by means of devices as perfect as possible and of concepts capable of generalization. This rule is one of the most important leers for overcoming mathematical difficulties and it seems to me that it is used almost always,though perhaps unconsciously.412DA VID HILBERTOccasionally it happens that we seek the solution under insufficient hypotheses or in an incorrect sense,and for this reason do not succeed.The problem then arises:to show the impossibility of the solution under the given hypotheses,or in the sense contemplated.Such proofs of impossibility were effected by the ancients, for instance when they showed that the ratio of the hypotenuse to the side of an isosceles right triangle is irrational.In later mathematics,the question as to the impossibility of certain solutions plays a pre¨e minent part,and we perceive in this way that old and difficult problems,such as the proof of the axiom of parallels,the squaring of the circle,or the solution of equations of thefifth degree by radicals havefinally found fully satisfactory and rigorous solutions,although in another sense than that originally intended.It is probably this important fact along with other philosophical reasons that gives rise to the conviction(which every mathematician shares,but which no one has as yet supported by a proof) that every definite mathematical problem must necessarily be susceptible of an exact settlement,either in the form of an actual answer to the question asked, or by the proof of the impossibility of its solution and therewith the necessary failure of all attempts.Take any definite unsolved problem,such as the question as to the irrationality of the Euler-Mascheroni constant C,or the existence of an infinite number of prime numbers of the form2n+1.However unapproachable these problems may seem to us and however helpless we stand before them,we have,nevertheless,thefirm conviction that their solution must follow by afinite number of purely logical processes.Is this axiom of the solvability of every problem a peculiarity characteristic of mathematical thought alone,or is it possibly a general law inherent in the nature of the mind,that all questions which it asks must be answerable?For in other sciences also one meets old problems which have been settled in a manner most satisfactory and most useful to science by the proof of their impossibility.I instance the problem of perpetual motion.After seeking in vain for the construction of a perpetual motion machine,the relations were investigated which must subsist between the forces of nature if such a machine is to be impossible;2and this inverted question led to the discovery of the law of the conservation of energy,which,again,explained the impossibility of perpetual motion in the sense originally intended.This conviction of the solvability of every mathematical problem is a powerful incentive to the worker.We hear within us the perpetual call:There is the problem. Seek its solution.You canfind it by pure reason,for in mathematics there is no ignorabimus.The supply of problems in mathematics is inexhaustible,and as soon as one problem is solved numerous others come forth in its place.Permit me in the fol-lowing,tentatively as it were,to mention particular definite problems,drawn from various branches of mathematics,from the discussion of which an advancement of science may be expected.Let us look at the principles of analysis and geometry.The most suggestive and notable achievements of the last century in thisfield are,as it seems to me,the arithmetical formulation of the concept of the continuum in the works of Cauchy, Bolzano and Cantor,and the discovery of non-euclidean geometry by Gauss,Bolyai,MATHEMATICAL PROBLEMS413 and Lobachevsky.I thereforefirst direct your attention to some problems belonging to thesefields.1.Cantor’s problem of the cardinal number of the continuumTwo systems,i.e.,two assemblages of ordinary real numbers or points,are said to be(according to Cantor)equivalent or of equal cardinal number,if they can be brought into a relation to one another such that to every number of the one assemblage corresponds one and only one definite number of the other.The inves-tigations of Cantor on such assemblages of points suggest a very plausible theorem, which nevertheless,in spite of the most strenuous efforts,no one has succeeded in proving.This is the theorem:Every system of infinitely many real numbers,i.e.,every assemblage of numbers (or points),is either equivalent to the assemblage of natural integers,1,2,3,...or to the assemblage of all real numbers and therefore to the continuum,that is,to the points of a line;as regards equivalence there are,therefore,only two assemblages of numbers,the countable assemblage and the continuum.From this theorem it would follow at once that the continuum has the next cardinal number beyond that of the countable assemblage;the proof of this theorem would,therefore,form a new bridge between the countable assemblage and the continuum.Let me mention another very remarkable statement of Cantor’s which stands in the closest connection with the theorem mentioned and which,perhaps,offers the key to its proof.Any system of real numbers is said to be ordered,if for every two numbers of the system it is determined which one is the earlier and which the later, and if at the same time this determination is of such a kind that,if a is before b and b is before c,then a always comes before c.The natural arrangement of numbers of a system is defined to be that in which the smaller precedes the larger.But there are,as is easily seen,infinitely many other ways in which the numbers of a system may be arranged.If we think of a definite arrangement of numbers and select from them a particular system of these numbers,a so-called partial system or assemblage,this partial system will also prove to be ordered.Now Cantor considers a particular kind of ordered assemblage which he designates as a well ordered assemblage and which is characterized in this way,that not only in the assemblage itself but also in every partial assemblage there exists afirst number.The system of integers1,2,3,...in their natural order is evidently a well ordered assemblage.On the other hand the system of all real numbers,i.e.,the continuum in its natural order,is evidently not well ordered.For,if we think of the points of a segment of a straight line,with its initial point excluded,as our partial assemblage,it will have nofirst element.The question now arises whether the totality of all numbers may not be arranged in another manner so that every partial assemblage may have afirst element,i.e., whether the continuum cannot be considered as a well ordered assemblage—a ques-tion which Cantor thinks must be answered in the affirmative.It appears to me most desirable to obtain a direct proof of this remarkable statement of Cantor’s, perhaps by actually giving an arrangement of numbers such that in every partial system afirst number can be pointed out.414DA VID HILBERT2.The compatibility of the arithmetical axiomsWhen we are engaged in investigating the foundations of a science,we must set up a system of axioms which contains an exact and complete description of the relations subsisting between the elementary ideas of that science.The axioms so set up are at the same time the definitions of those elementary ideas;and no statement within the realm of the science whose foundation we are testing is held to be correct unless it can be derived from those axioms by means of afinite number of logical steps.Upon closer consideration the question arises:Whether,in any way,certain statements of single axioms depend upon one another,and whether the axioms may not therefore contain certain parts in common,which must be isolated if one wishes to arrive at a system of axioms that shall be altogether independent of one another.But above all I wish to designate the following as the most important among the numerous questions which can be asked with regard to the axioms:To prove that they are not contradictory,that is,that afinite number of logical steps based upon them can never lead to contradictory results.In geometry,the proof of the compatibility of the axioms can be effected by constructing a suitablefield of numbers,such that analogous relations between the numbers of thisfield correspond to the geometrical axioms.Any contradiction in the deductions from the geometrical axioms must thereupon be recognizable in the arithmetic of thisfield of numbers.In this way the desired proof for the compatibility of the geometrical axioms is made to depend upon the theorem of the compatibility of the arithmetical axioms.On the other hand a direct method is needed for the proof of the compatibility of the arithmetical axioms.The axioms of arithmetic are essentially nothing else than the known rules of calculation,with the addition of the axiom of continuity.I recently collected them3and in so doing replaced the axiom of continuity by two simpler axioms,namely,the well-known axiom of Archimedes,and a new axiom essentially as follows:that numbers form a system of things which is capable of no further extension,as long as all the other axioms hold(axiom of completeness).I am convinced that it must be possible tofind a direct proof for the compatibility of the arithmetical axioms,by means of a careful study and suitable modification of the known methods of reasoning in the theory of irrational numbers.To show the significance of the problem from another point of view,I add the following observation:If contradictory attributes be assigned to a concept,I say, that mathematically the concept does not exist.So,for example,a real number whose square is−1does not exist mathematically.But if it can be proved that the attributes assigned to the concept can never lead to a contradiction by the application of afinite number of logical processes,I say that the mathematical existence of the concept(for example,of a number or a function which satisfies certain conditions)is thereby proved.In the case before us,where we are concerned with the axioms of real numbers in arithmetic,the proof of the compatibility of the axioms is at the same time the proof of the mathematical existence of the complete system of real numbers or of the continuum.Indeed,when the proof for the compatibility of the axioms shall be fully accomplished,the doubts which have been expressed occasionally as to the existence of the complete system of real numbers will become totally groundless.The totality of real numbers,i.e., the continuum according to the point of view just indicated,is not the totality of。

(完整word版)剑桥雅思8阅读理解解析含翻译

(完整word版)剑桥雅思8阅读理解解析含翻译

剑桥雅思8-第三套试题-阅读部分-PASSAGE 1-阅读真题原文部分:READING PASSAGE 1You should spend about 20 minutes on Questions 1-13 which are based on Reading Passage 1 below.Striking Back at Lightning With LasersSeldom is the weather more dramatic than when thunderstorms strike. Their electrical fury inflicts death or serious injury on around 500 people each year in the United States alone. As the clouds roll in, a leisurely round of golf can become a terrifying dice with death - out in the open, a lone golfer may be a lightning bolt's most inviting target. And there is damage to property too. Lightning damage costs American power companies more than $100 million a year.But researchers in the United States and Japan are planning to hit back. Already in laboratory trials they have tested strategies for neutralising the power of thunderstorms, and this winter they will brave real storms, equipped with an armoury of lasers that they will be pointing towards the heavens to discharge thunderclouds before lightning can strike.The idea of forcing storm clouds to discharge their lightning on command is not new. In the early 1960s, researchers tried firing rockets trailing wires into thunderclouds to set up an easy discharge path for the huge electric charges that these clouds generate. The technique survives to this day at a test site in Florida run by the University of Florida, with support from the Electrical Power Research Institute (EPRI), based in California. EPRI, which is funded by power companies, is looking at ways to protect the United States' power grid from lightning strikes. 'We can cause the lightning to strike where we want it to using rockets, ' says Ralph Bernstein, manager of lightning projects at EPRI. The rocket site is providing precise measurements of lightning voltages and allowing engineers to check how electrical equipment bears up.Bad behaviourBut while rockets are fine for research, they cannot provide the protection from lightning strikes that everyone is looking for. The rockets cost around $1, 200 each, can only be fired at a limited frequency and their failure rate is about 40 per cent. And even when they do trigger lightning, things still do not always go according to plan. 'Lightning is not perfectly well behaved, 'says Bernstein. 'Occasionally, it will take a branch and go someplace it wasn't supposed to go. ' And anyway, who would want to fire streams of rockets in a populated area? 'What goes up must come down, ' points out Jean-Claude Diels of the University of New Mexico. Diels is leading a project, which is backed by EPRI, to try to use lasers to discharge lightning safely - and safety is a basic requirement since no one wants to put themselves or their expensive equipment at risk. With around $500, 000 invested so far, a promising system is just emerging from the laboratory.The idea began some 20 years ago, when high-powered lasers were revealing their ability to extract electrons out of atoms and create ions. If a laser could generate a line of ionisation in the air all the way up to a storm cloud, this conducting path could be used to guide lightning to Earth, before the electric field becomes strong enough to break down the air in an uncontrollable surge. To stop the laser itself being struck, it would not be pointed straight at the clouds. Instead it would be directed at a mirror, and from there into the sky. The mirror would be protected by placing lightning conductors close by. Ideally, the cloud-zapper (gun)would be cheap enough to be installed around all key power installations, and portable enough to be taken to international sporting events to beam up at brewing storm clouds.A stumbling blockHowever, there is still a big stumbling block. The laser is no nifty portable: it's a monster that takes up a whole room. Diels is trying to cut down the size and says that a laser around the size of a small table is in the offing. He plans to test this more manageable system on live thunderclouds next summer.Bernstein says that Diels's system is attracting lots of interest from the power companies. But they have not yet come up with the $5 million that EPRI says will be needed to develop a commercial system, by making the lasers yet smaller and cheaper. 'I cannot say I have money yet, but I'm working on it, ' says Bernstein. He reckons that the forthcoming field tests will be the turning point - and he's hoping for good news. Bernstein predicts 'an avalanche of interest and support' if all goes well. He expects to see cloud-zappers eventually costing 100, 000 each.Other scientists could also benefit. With a lightning 'switch' at their fingertips, materials scientists could find out what happens when mighty currents meet matter. Diels also hopes to see the birth of 'interactive meteorology' - not just forecasting the weather but controlling it. 'If we could discharge clouds, we might affect the weather, ' he says.And perhaps, says Diels, we'll be able to confront some other meteorological menaces. 'We think we could prevent hail by inducing lightning, ' he says. Thunder, the shock wave that comes from a lightning flash, is thought to be the trigger for the torrential rain that is typical of storms. A laser thunder factory could shake the moisture out of clouds, perhaps preventing the formation of the giant hailstones that threaten crops. With luck, as the storm clouds gather this winter, laser-toting researchers could, for the first time, strike back.Questions 1-3Choose the correct letter, A, B, C or D.Write the correct letter in boxes 1-3 on your answer sheet.1 The main topic discussed in the text isA the damage caused to US golf courses and golf players by lightning strikes.B the effect of lightning on power supplies in the US and in Japan.C a variety of methods used in trying to control lightning strikes.D a laser technique used in trying to control lightning strikes.2 According to the text, every year lightningA does considerable damage to buildings during thunderstorms.B kills or injures mainly golfers in the United States.C kills or injures around 500 people throughout the world.D damages more than 100 American power companies.3 Researchers at the University of Florida and at the University of New MexicoA receive funds from the same source.B are using the same techniques.C are employed by commercial companies.D are in opposition to each other.Questions 4-6Complete the sentences below.Choose NO MORE THAN TWO WORDS from the passage for each answer.Write your answers in boxes 4-6 on your answer sheet.4 EPRI receives financial support from………………………….5 The advantage of the technique being developed by Diels is that it can be used……………….6 The main difficulty associated with using the laser equipment is related to its……………….Questions 7-10Complete the summary using the list of words, A-I, below.Write the correct letter, A-I, in boxes 7-10 on your answer sheet.In this method, a laser is used to create a line of ionisation by removing electrons from 7 …………………………. This laser is then directed at 8 …………………………in order to control electrical charges, a method which is less dangerous than using 9 …………………………. As a protection for the lasers, the beams are aimed firstly at 10………………………….A cloud-zappersB atomsC storm cloudsD mirrorsE techniqueF ionsG rockets H conductors I thunderQuestions 11-13Do the following statements agree with the information given in Reading Passage 1?In boxes 11-13 on your answer sheet writeYES if the statement agrees with the claims of the writerNO if the statement contradicts the claims of the writerNOT GIVEN if it is impossible to say what the writer thinks about this11 Power companies have given Diels enough money to develop his laser.12 Obtaining money to improve the lasers will depend on tests in real storms.13 Weather forecasters are intensely interested in Diels's system.READING PASSAGE 1篇章结构体裁说明文主题用激光回击闪电结构第1段:闪电带来的危害第2段:科研人员正在研究回击闪电的方法第3段:先前的闪电回击术介绍第4段:火箭回击术的缺陷第5段:更安全的激光回击术第6段:激光回击术的技术原理第7段:激光回击术的缺陷第8段:通过实地实验改进激光回击术第9段:激光回击术对其他学科也有益处第10段:激光回击术的其他用途解题地图难度系数:★★★解题顺序:按题目顺序解答即可友情提示:烤鸭们注意:本文中的SUMMARY题目顺序有改变,解题要小心;MULTIPLE CHOICE的第三题是个亮点,爱浮想联翩的烤鸭们可能会糊掉。

专业英语2第六单元B翻译

专业英语2第六单元B翻译

Separation of Powers in the American Public Law美国公法中的三权分立It has already been intimated that Montesquieu’s theory(指孟德斯鸠的三权分立理论)of the separation of powers was made the basis of the system of government adopted in the United States at the end of the eighteenth century.A perusal of the writings of those men who influenced most profoundly the political thought of the time will reveal a practically unanimous 1acceptance of the theory.我们都知道,孟德斯鸠的三权分立学说是美国在18世纪末组建政府体系的理论基础,一些熟读相关政治理论作品且在政治领域有很大影响力的学者认为,时间会证明,总有一天绝大多数的人都会接受这一理论。

The theory was accepted not ,however ,as a scientific theory but as a legal rule. Many of the state constitutions, which either were adopted soon after the American revolution or have been put into force since , contain clauses known as “distributing clauses,” of which that contained in the constitution of Massachusetts(马萨诸塞州)may be taken as a most forcible example. Article 30 of the first constitution of Massachusetts provides that “in the government of this common-wealth the legislative department shall never exercise the executive or judiciary powers or either of them;the executive shall never exercise the legislative or judicial powers or either of them;the judiciary shall never exercise the legislative or executive powers or either of them,to the end that it may be a government of laws and not of men.” Other constitutions, of which the constitution of the United States is one , provide that the legislative power shall be vested in a legislature, that the executive power shall be vested in a President or governor , and that the judicial power shall be vested in certain courts.Such provisions,however ,are held to have practically the same legal effect as the distributing clause in the Massachusetts constitution, on the theory th at “affirmative(肯定的)words are often , in their operation , negative of other objects than those affirmed.”这个理论并没有被全面接受,更多的时候它只是一个科学的理论而不是法律规章。

唯愿世界和平英语作文

唯愿世界和平英语作文

Peace is a universal aspiration, a dream that resonates with every soul. In our world today, where conflicts and strife are all too common, the desire for peace is more relevant than ever. Here is an essay on the importance of world peace and the role each of us can play in fostering it.In the vast tapestry of human history, the pursuit of peace has been a constant thread. Yet, despite our best efforts, the world continues to witness acts of violence, war, and discord. It is a stark reminder that the quest for peace is an ongoing journey, one that requires the collective efforts of every individual. This essay aims to explore the significance of world peace and the steps we can take to contribute to it.The Importance of World PeaceWorld peace is not merely the absence of war it is a state of harmony, understanding, and cooperation among nations and people. It is a world where diplomacy triumphs over aggression, where dialogue replaces bullets, and where compassion is the currency of human interaction. The benefits of a peaceful world are manifold:1. Economic Prosperity: Peace allows for the free flow of trade and resources, fostering economic growth and reducing poverty.2. Cultural Exchange: It promotes the exchange of ideas, art, and traditions, enriching the global community.3. Environmental Sustainability: A peaceful world is more likely to prioritize the preservation of our planet, working together to combat climate change and protect biodiversity.4. Human Development: Peace provides a stable environment for education, healthcare, and social development, improving the quality of life for all.Individual Actions for World PeaceWhile the concept of world peace may seem daunting, there are tangible actions each of us can take to contribute to this noble cause:1. Educate Ourselves: Understanding the root causes of conflicts and the values of different cultures is the first step towards empathy and respect.2. Promote Dialogue: Engage in conversations that bridge divides, whether they are political, religious, or social.3. Support Peaceful Initiatives: Donate to or volunteer with organizations that worktowards conflict resolution and peacebuilding.4. Practice Tolerance: In our daily lives, we can choose to be tolerant and understanding, even in the face of disagreement.5. Advocate for Peace: Use our voices to advocate for policies and leaders that prioritize peace and diplomacy.ConclusionThe dream of a peaceful world is not unattainable it is a goal that can be achieved through persistent and collective effort. As individuals, we hold the power to influence our communities and, by extension, the world. By embracing the values of peace, we can work towards a future where harmony and cooperation are the norm, not the exception. In conclusion, world peace is a vision that deserves our unwavering commitment. It is a testament to our humanity and our potential to create a better world for all. Let us take up the mantle of peace, not just as a hope, but as a mission that we are all dutybound to fulfill.。

高级英语Book5学习资料lesson1

高级英语Book5学习资料lesson1

LessonOne Salvation1. 课文译文救赎兰斯顿.休斯在我快13岁那年,我的灵魂得到了拯救,然而并不是真正意义上的救赎。

事情是这样的。

那时我的阿姨里德所在的教堂正在举行一场盛大的宗教复兴晚会。

数个星期以来每个夜晚,人们在那里讲道,唱诵,祈祷。

连一些罪孽深重的人都获得了耶稣的救赎,教堂的成员一下子增多了。

就在复兴晚会结束之前,他们为孩子们举行了一次特殊的集会——把小羊羔带回羊圈。

里德阿姨数日之前就开始和我提这件事。

那天晚上,我和其他还没有得到主宽恕的小忏悔者们被送去坐在教堂前排,那是为祷告的人安排的座椅。

我的阿姨告诉我说:“当你看到耶稣的时候,你看见一道光,然后感觉心里似乎有什么发生。

从此以后耶稣就进入了你的生命,他将与你同在。

你能够看见、听到、感受到他和你的灵魂融为一体。

”我相信里德阿姨说的,许多老人都这么说,似乎她们都应该知道。

尽管教堂里面拥挤而闷热,我依然静静地坐在那里,等待耶稣的到来。

布道师祷告,富有节奏,非常精彩。

呻吟、喊叫、寂寞的呼喊,还有地狱中令人恐怖的画面。

然后他唱了一首赞美诗。

诗中描述了99只羊都安逸的待在圈里,唯有一只被冷落在外。

唱完后他说道:“难道你不来吗?不来到耶稣身旁吗?小羊羔们,难道你们不来吗?”他向坐在祷告席上的小忏悔者们打开了双臂,小女孩们开始哭了,她们中有一些很快跳了起来,跑了过去。

我们大多数仍然坐在那里。

许多长辈过来跪在我们的身边开始祷告。

老妇人的脸像煤炭一样黑,头上扎着辫子,老爷爷的手因长年的劳作而粗糙皲裂。

他们吟唱着“点燃微弱的灯,让可怜的灵魂得到救赎”的诗歌。

整个教堂里到处都是祈祷者的歌声。

最后其他所有小忏悔者们都去了圣坛上,得到了救赎,除了一个男孩和依然静静地坐着等侯的我。

那个男孩是一个守夜人的儿子,名字叫威斯特里。

在我们的周围尽是祈祷的修女、执事。

教堂里异常闷热,天色也越来越暗了。

最后威斯特里小声对我说:“去他妈的上帝。

我再也坐不住了,我们站起来吧,就可以得到救赎了。

21世纪大学英语读写教程第三册单词及课后翻译-Unit6

21世纪大学英语读写教程第三册单词及课后翻译-Unit6

Unit 6 Text ANew Wordsfunera‎ln. 葬礼beern. 啤酒* cockta‎iln. 鸡尾酒painfu‎la. 令人痛苦的;疼痛的admini‎strati‎onn. 1. 管理;行政;经营2.管理部门;行政机关longti‎mea.(已持续)长时期的,为时甚久的rodn. 杆;棒条* thighn. 大腿zonen. 地带,地区injure‎vt. 伤害,损害injury‎n. (对生物的)伤害;(对身体或名誉‎的)伤害,损害drunkn. 酗酒者,醉汉a. 醉酒的;(喻)陶醉的* reveng‎en. (for, on) 复仇;报复vt. 报…之仇;为…报仇involu‎ntaril‎yad. 非自愿地;非出于本意地‎accomp‎lishme‎ntn. 完成;实现;成绩;造诣;技能maidn. 1. 女仆,保姆2. 少女,年轻女子newbor‎na.新生的,刚生的niecen. 侄女;甥女bride-to-bea.未来的新娘vown. 誓言vt. 立誓fragme‎ntvi. 破碎;碎裂n. 碎片guidan‎cen. 引导;指导vacant‎a. 1. 空的;未被占用的2. 空缺的intima‎cyn. 亲密;密切intima‎tea. 1. 亲密的;密切的12. 个人的;私人的despai‎rn. 绝望vi. (of) 绝望;失去希望* shatte‎rvt. 粉碎;砸碎confin‎esn. (fml) (正式)界限;边界;范围leakv. 1. (使)渗漏2. (使)泄露出去n. 漏隙;漏出物explod‎ev. 1. (使某物)爆炸2.(指感情)爆发,突发,迸发;(指人)冲动,激动* defyvt. 违抗;蔑视* defian‎cen. 违抗;蔑视* soothe‎vt. 抚慰;使平静nightm‎aren. 恶梦irreve‎rsibil‎ityn. 不可挽回;不可逆转blurv. (是某物)变得模糊不清‎fadevi. 1. (away) 逐渐消失2. 衰颓;褪色;凋谢nothin‎gnessn. 不存在的;无,虚无unbear‎ablea.难以忍受的;不能容忍的;难以承受的Phrase‎s and Expres‎sionsgo out of contro‎lbe no longer‎under contro‎l 失去控制smash intohit forcef‎ully agains‎t 猛地撞在…head onwith the head or front parts meetin‎g violen‎tly 迎面地,正面地by chance‎by accide‎nt; uninte‎ntiona‎lly 偶然地;意外地commen‎t onmake a remark‎or give an opinio‎n on 评论;就…发表意见make a differ‎ence有影响;起作用take back one's wordsadmit that one was wrong in what one has said 收回说过的话‎maid of honor首席女傧相[n.]-to-be未来的…fade intogradua‎lly disapp‎ear and become‎(sth. of no import‎ance) 逐渐消失而变‎成(无足轻重的2东‎西)pull up [to/at/in front of a place] (of vehicl‎es) drive up to and stop at (车辆)到达,驶入Every 23 minute‎s 每23分钟。

大学英语精读4课后翻译

大学英语精读4课后翻译

unit21.比尔已是个成熟的小伙子,不再依赖父母替他作主。

Bill is a mature young man who is no longer dependent on his parents for decisions.2.这个地区有大量肉类供应,但新鲜果蔬奇缺。

There are abundant supplies of meat in this region, but fresh fruit and vegetables are scarce.3.工程师们依靠工人们的智慧,发明了一种新的生产方法,使生产率得以提高。

Drawing on the wisdom of the workers, the engineers invented a new production method that ledto increased productivity.4.他花了许多时间准备数学考试,因此当他获知自己只得了个B时感到有点失望。

He spent a lot of time preparing for his math exam. Hence he was somewhat disappointed to learn that he got only a B.5.我们有充裕的时间从从容容吃顿午饭。

We have ample time for a leisurely lunch.6.地方政府不得不动用储备粮并采取其他紧急措施,以便渡过粮食危机。

The local government had to draw on its grain reserves and take other emergency measures so as to pull through the food crisis.unit51.我确信这项所谓明智的决定,与期望相反,会带来极其严重的后果。

I am convinced that, contrary to expectations, the so-called informed decision will bring very grave consequences.2. 诚然,他曾欺骗你,但他已经承认自己做错了,并道了歉。

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βn∗,k,q =
1
nn
n
(−1)m
mq
(n−1)(k−1) 2
+k+m−2
1−q
m=0
m
(1

qm−
n−1 2
−2)(1

qm−
n−1 2
)
.
We define generating function Fk∗,q(t; k) of the q-Bernoulli polynomials βn∗,k,q(k) ( n ≥ 0 ) as follows:
of consecutive integers.
In [6], Garrett and Hummel gave a combinatorial proof of a q-analogue of
n+1 2
2
as
follows:
n k=1
k3
=
n
qk−1
k=1
1 − qk 2 1−q
1 − qk−1 1 − q2
[k]q
2
[k
]qm−1
q(n−k)
m+1 2
.
k=1
(1.2)
Then Warnaar[23](for m = 3) and Schlosser[21] gave formulae for m = 1, 2, 3, 4, 5 as
the meaning of the q-analogues of the sums of consecutive integers, squares, cubes, quarts
Recently, the problem of q-analogues of the sums of powers have attracted the attention of several authors([8],[9],[15],[19],[21],[23]). Let
n
Sm,n(q) =
arXiv:math/0503209v1 [math.NT] 11 Mar 2005
A NOTE ON THE SUMS OF POWERS OF CONSECUTIVE q-INTEGERS
YILMAZ SIMSEK Mersin University, Faculty of Science, Department of Mathematics 33343 Mersin,
Korea tkim@kongju.ac.kr
Seog-Hoon Rim Department of Mathematics Education, Kyungpook National University, Taegu 702-701,
Korea shrim@knu.ac.kr
Abstract. In this paper we construct the q-analogue of Barnes’s Bernoulli numbers and polynomials of degree 2, for positive even integers, which is an answer to a part of Schlosser’s question. For positive odd integers, Schlosser’s question is still open. Finally, we will treat the q-analogue of the sums of powers of consecutive integers.
For any positive integers n, k(> 1), h ∈ Z, let
k−1
Sn,qh (k) = qhj[j]nq .
j=0
2
Then, he obtained the interesting formula for Sn,q(k) below:
Sn,q (k)
=
1 n+1

Fk∗,q(t) = −t
qk−j [j]q2
exp(t[j]qq
k−j 2
)
j=0
(1.3)
= ∞ βn∗,k,qtn (cf. [10], [11], [12], [13], [14], [15], [16]). n=0 n!
Theorem 1. Let k, n be positive integers with n ≡ 0 (mod 2). Then
+
1 − qk+1 1 − q2
=
n+1
2
,
2q
where
n k
q
=
k j=1
1
− qn+1−j 1 − qj
denotes the q-binomial coefficient. Garrett and Hummel, in their paper, asked for a simpler q-analogue of the sum of cubes . As a response to Garrett and Hummel’s question, Warnaar gave a simple q-analogue of the sum of cubes as follows:
Turkey ysimsek@.tr
Daeyeoul Kim Dept. of Math., Chonbuk National
University, Chonju, 561-756, Korea
daeyeoul@chonbuk.ac.kr
TAEKYUN KIM Institute of Science Education, Kongju National University Kongju 314-701,
any integer k define the q-integer as
qk − 1 [k]q = q − 1 , (cf. [11],[12],[13],[16],[17]).
Note that limq→1[k]q = k. Recently, many authors studied q-analogue of the sums of powers
2000 AMS Subject Classification: 11B68, 11S40. keywords and phrases :Sums of powers, Bernoulli Numbers, q-Bernoulli Numbers, zeta function, Dirichlet series
and quints. By two families of polynomials and Vandermonde determinant, Guo and
Zeng[9] found the formulae for the q-analogues of the sums of consecutive integers (for
Sm,n(q), which is defined in (1.2), and left it as an open problem. By using Kim’s technical method to construct q-Bernoulli numbers and polynomials in
Typeset by AMS-TEX
1
1. Introduction
In 1713, J. Bernoulli first discovered the method which one can produce those formulae
for the sum
n j=1
jk,
for
any
natural
[10],[11],[12],[13],[14],[15],[16],[19], for positive even integers, we construct the q-analogue
of Barnes’ Bernoulli numbers and polynomials of degree 2, which is an answer to a part of
n m=0
n (−1)m m
mqk(m−1)
mqk(m+1)
1

qm−
n−1 2
−2

1

qm−
n−1 2
numbers
k
(cf.
Байду номын сангаас
[1],[3],[6],[7],[15],[22]).
The
Bernoulli
numbers are among the most interesting and important number sequences in mathemat-
ics. These numbers first appeared in the posthumous work “ Ars Conjectandi” (1713)
by Jakob Bernoulli(1654-1705) in connection with sums of powers of consecutive integers(
Bernoulli(1713) or D. E. Smith(1959) see [15]).
Let q be an indeterminate which can be considered in complex number field, and for
m = 1, 2, ..., 11) by which they recovered the formulae of Warnaar(for m = 3) and Schlosser
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