精彩无限，尽在智力快车

1．请问哪里的佛像最少？A．南半球B．北半球C．赤道.2．3个人3天用3桶水,9个人9天用几桶水？A．3桶B．9桶C．27桶.3．什么动物的牙齿最好？A．狼B．老虎C．老鼠.4．读完北京大学需要多久？A．一秒钟B．4年C．一辈子.5．关羽为什么比张飞死得早？A．身体虚弱B．奋战沙场C．红颜薄命。     

贝卡的历险日记

担心着．担心着．北风来了,冰雪的脚步近了。一切都像没睡醒的样子．昏昏然紧闭着喉。山冷冻起来了．水凉起来了太阳在地平线下躲起来了．海豹偷偷地从水里钻出来．傻傻的．胖胖的．海洋里．浮冰上．瞧去．一大片一大片满是的．坐着．漂着．打两个滚．踢几块．水．赛几趟泳．捉几回迷藏。     

数学基础课是通向数学主流的门户

2007年．作者翻译T．Needham所写的《可视的复分析》（Visual Complex Analysis．Oxford Univ．Press．2006）一书．以为这是一本很好的教本．值得许多同志花一点时间读一下．译后有一些感想．因此写了一篇较长的译后记．主要思想即认为数学基础课是通向数学主流的门户．译本将由人民邮电出版社出版．现在征得出版社的同意,将这篇译后记发表于此．在发表时又作了一点补充．补写的文字放在方括号内．     

十二省市(辽宁、云南、湖南、乌鲁木齐、昆明、哈尔滨、山西、广西、西宁、河南、嘉兴等、甘肃)填空题集萃

数与式１．计算９３ｘ－７１２ｘ＋２６·３８ｘ＝．２．－１３的倒数是．３．（－６）２＝．４．２０００用科学记数法表示为．５．ａ的３倍与ｂ的一半的和用代数式表示为．６．分解因式ａ２－２ａｂ＋ｂ２－ｃ２＝．７．配上适当的数,使等式ｘ２－ｘ＋１＝（ｘ－）２＋成立．８．３５的相反数是,｜－６｜＝．９．用科学记数法表示：５７００００＝．１０．分解因式：ａ－ａｂ２＝．１１．已知线段ａ＝４ｃｍ,ｂ＝９ｃｍ,则线段ａ、ｂ的比例中项ｃ＝ｃｍ．１２．化简：ａ（ａ－１）２－（ａ＋１）（ａ２－ａ＋１）＝．１３．计算：（ａ…     

小学初中数学衔接研究

第１课　数的运算回顾思考１．甲数与０．５的和是５６则甲数是．２．３１２的４倍是,一个数的３倍是１２则这个数是．３．比数３．２５多３倍的数是,比数ａ多３倍的数是１３,则ａ＝．４．５．２５的２３是,数ｂ的２５是２４５,则ｂ＝．５．比２５多１２％的数是,比数ｘ少４％的数是１．９２,则ｘ＝．解题指导与能力培养例１　计算１．［７３４＋５８×（２３４－１３２０）］－１０２３÷２×３２２．［３．７５－（０．２＋１３）×４．５］÷（８１２＋５．４５）答案１．３４;２．０．１评析　１．混合运算应注意审题,明确运算…     

有理数目标检测题(一)

一、填空１．在数轴上表示的两个数的数总比的数小．２．－２１３的相反数是,倒数是．３．绝对值等于１１的有理数是．４．把－０．３,１,１２,０按从小到大的顺序,用“＜”号连接为．５．如果－３ｘ＝－９,那么ｘ＝．６．如果ｘ＞０,并且－ｘ２＝－４,那么ｘ＝．７．大于－１,而小于４的所有整数的乘积是．８．若ａ与ｂ互为相反数,则ａ３＋ｂ３＝．９．计算（－１）１９９８＋（－１）１９９９＝．１０．近似数：１．７０×１０５有个有效数字,精确到位．二、选择１．下列说法正确的是（　）（Ａ）符号不同的两个数互为相反数（…     

《数学建模》前言

《数学建模》前言［英］Ｊ．Ｄ．ＨｕｔｎｌｅｙＤ．Ｊ．Ｇ．Ｊａｍｅｓ著编译者的话《数学建模》是英国数学教育家Ｊ．Ｄ．亨特利与Ｄ．Ｊ．Ｇ．詹姆斯的著作，１９９０年由牛津大学出版社出版．该书选择了社会生产与生活中具有典型意义的２８个实际问题．通过对这些问题...     

CFO式经典旅游线路

财务经理人经常考虑的问题：成本，现金流．公司治理．与老板的关系．组织结构．与银行的关系．工作流程，资产管理／投资回报．上市公司．Measurement体系，财务理念．价格体系．效率，品质，产品战略．会计信息和ERP系统。而以下旅游线路为CFO量身打造。     

关于Fuzzy度量点式刻画的一点注记

本文中重新定义由一个点式Ｆｕｚｚｙｐ．ｑ．度量ｄ所诱导的Ｆｕｚｚｙｐ．ｑ．度量｛Ｄｒ｜ｒ＞０｝（代替［１］中的相关重域映射族）．在新的定义下，点式Ｆｕｚｚｙｐ．ｑ．（ｐ．）度量与Ｆｕｚｚｙｐ．ｐ．（ｐ．）度量之间有令人满意的──对应关系．     

中国数学会计算数学学会年会征文通知

中国数学会计算数学学会年会拟于１９９９年１０月６—１０日在上海师范大学召开．会议热忱欢迎从事计算数学及其相关领域的科研、教学和工程技术人员参加．请欲参加会议者．于１９９９年４月３０日前将论文中文摘要（１０００字以内．内容包括;１．题目;２．作者;３．工作单位;４．摘要）．及其ＴＥＸ文件（用软件或ＥＭＡＩＬ）,以及回执寄至汤华中．张时珍：（１０００８０）北京２７１９信箱．中科院计算数学与科学工程计算研究所ＥＭＡＩＬＳ：ｔｈｚ＠ｌｓｅｃ．ｃｃ．ａｃ．ｃｎ;ｚｓｚ＠ｌｓｅｃ．ｃｃ．ａｃ．ｃｎ．会议筹备…     

Formulation of linear problems and solution by a universal machine

Using the predicate language for ordered fields a class of problems referred to aslinear problems is defined. This class contains, for example, all systems of linear equations and inequalities, all linear programming problems, all integer programming problems with bounded variables, all linear complementarity problems, the testing of whether sets that are defined by linear inequalities are semilattices, all satisfiability problems in sentenial logic, the rank-computation of matrices, the computation of row-reduced echelon forms of matrices, and all quadratic programming problems with bounded variables. A single, one, algorithm, to which we refer as theUniversal Linear Machine, is described. It solves any instance of any linear problem. The Universal Linear Machine runs in two phases. Given a linear problem, in the first phase a Compiler running on a Turing Machine generates alinear algorithm for the problem. Then, given an instance of the linear problem, in the second phase the linear algorithm solves the particular instance of the linear problem. The linear algorithm is finite, deterministic, loopless and executes only the five ordered field operations — additions, multiplications, subtractions, divisions and comparisons. Conversely, we show that for each linear algorithm there is a linear problem which the linear algorithm solves uniquely. Finally, it is shown that with a linear algorithm for a linear problem, one can solve certain parametric instances of the linear problem.Research was supported in part by the National Science Foundation Grant DMS 92-07409, by the Department of Energy Grant DE-FG03-87-ER-25028, by the United States—Israel Binational Science Foundation Grant 90-00434 and by ONR Grant N00014-92-J1142.Corresponding author.     

A double-stage piecewise recursive filter for real-time applications

This paper examines the basic problem of estimating the state of a system described by a set of dynamical equations. The state estimation is performed by means of optimal filtering techniques in which the state observation is given by a set of nonlinear equations.The basic issue encountered in most engineering problems is the availability of more observable information than the processor can effectively process in real-time, while performing full optimal filtering on all available observable data. To alleviate this deficiency, an algorithm is developed in which the rate of information processing is kept at a high value, while the system statistics are evaluated at a much slower rate.The method utilizes a combination of fast and slow filtering loops, in which the observable data are processed at a high rate during the fast loop, while the system error covariance, gain computations, and all other system statistics are processed at a lower rate in the slow loop. Methods are provided to resolve any incompatibility in the system statistics resulting from this fast-loop/slow-loop processing combination.Applications describing problems pertaining to aircraft navigation are presented. Specifically, applications to aircraft navigation through a satellite network are studied. Appropriate simulation results from the above studies are shown.This work was performed under contract with the Department of the Air Force, Space and Missile Organization (SAMSO), Los Angeles, California, Contract No. F04-701-75-C-0180.The authors are indebted to Dr. C. Johnson, GPS System Engineer, Mr. G. Consolver, GPS Software Manager, and Mr. W. Riley, Communications/Navigation Department, Texas Instruments for their continuous encouragement in the course of this work. Also, they are indebted to Major M. Birnbaum, SAMSO, for his constructive criticism on the conceptual design of this work, and to Mr. A. Bierman, Aerospace Corporation, for kindly providing simulation data of aircraft trajectories. Finally, the authors would like to express their gratitude to Dr. N. Carlson, Intermetrics, for valuable consultation during the progress of this work.Portions of this paper were presented by the senior author at the GSP Conference, Plan 76, IEEE Position, Location, and Navigation Symposium, San Diego, California, 1976.     

基于模糊FNN-ELECTRE法的国有商业银行竞争力评价

随着金融业全方位开放,国有商业银行已成为国家经济命脉的核心,其竞争力强弱关系着国家经济的繁荣与衰退。本文基于模糊FNN-ELECTRE方法建立国有商业银行竞争力评价模型,以因素神经网络理论(FNN)与ELECTRE融合方法为基础,以现有商业银行竞争力评价指标为着眼,把国有商业银行竞争力的评价体系从现实竞争力和潜在竞争力两个因素抽取为一级指标,以规模、质量、业务结构、效率、成长性五个因素设为二级指标。从实证的角度对银行A、银行B、银行C、银行D、银行E五大国有银行进行分析验证,对其属性值进行和谐性与非和谐性检验得出,银行B竞争能力最强,银行E竞争能力最弱,五大国有银行均有改进空间。     

Representation of the solution to a model problem in semiconductor physics

We study a mixed type problem for the Poisson equation arising in the modeling of charge transport in semiconductor devices [V. Romano, 2D simulation of a silicon MESFET with a non-parabolic hydrodynamical model based on the maximum entropy principle, J. Comput. Phys. 176 (2002) 70-92; A.M. Blokhin, R.S. Bushmanov, A.S. Rudometova, V. Romano, Linear asymptotic stability of the equilibrium state for the 2D MEP hydrodynamical model of charge transport in semiconductors, Nonlinear Anal. 65 (2006) 1018-1038]. Unlike well-studied elliptic boundary-value problems in domains with smooth boundaries (see, for example, [O.A. Ladyzhenskaya, N.N. Uralceva, Linear and Quasilinear Elliptic Equations, Nauka, Moscow, 1973; D. Gilbarg, N.S. Trudinger, Elliptic Partial Differential Equations of Second Order, Springer-Verlag, Berlin, 1983]), our problem has two significant features: firstly, the boundary is not a smooth curve and, secondly, the type of boundary conditions is mixed (the Dirichlet condition is satisfied on the one part of the boundary whereas the Neumann condition on the other part). The well-posedness of the problem in Hölder and Sobolev spaces is proved. The representation of the solution to the problem is obtained in an explicit form.     

金融风险在股票市场的传染效应及联动行为分析

近年来金融危机频发并表现出了易传染性,引起了众多学者的高度关注。以动态条件相关模型研究美欧股市与中、日、韩股市间的时变相关性,并结合内生多重结构突变模型划分危机传染阶段,选用溢出指数模型分析股市间的风险溢出特性;随后,定义股市间相互影响的联动模式并构建不同传染阶段的加权有向网络图分析股市间的联动行为。研究表明:美欧股市对中日韩股市有明显的传染效应,被传染的速度和持续时间均不相同;金融传染和风险溢出展现出一定的不一致性,危机期间日股的风险溢出效应强于美股;传染效应在联动网络中表现为联动模式的高聚类性和高联动性,相比欧债危机,次贷危机时期股市间展现出更强的联动行为;日股与美欧股市在两次危机中均表现出最强的联动性,其所受影响也最大。     

Wave parameter identification problem for ocean test structure data,part 2, discrete formulation

This paper deals with the solution of the wave parameter identification problem for ocean test structure data. A discrete formulation is assumed. An ocean test structure is considered, and wave elevation and velocities are assumed to be measured with a number of sensors. Within the frame of linear wave theory, a Fourier series model is chosen for the wave elevation and velocities. Then, the following problem is posed: Find the amplitudes of the various wave components of specified frequency and direction, so that the assumed model of wave elevation and velocities provides the best fit to the measured data. Here, the term best fit is employed in the least-square sense over a given time interval.At each time instant, the wave representation involves four indexes (frequency, direction, instrument, time); hence, four-dimensional arrays are required. This formal difficulty can be avoided by switching to an alternative representation involving only two indexes (frequency-direction, instrument-time); hence, standard vector-matrix notation can be used. Within this frame, optimality conditions are derived for the amplitudes of the assumed wave model.A characteristic of the wave parameter identification problem is that the condition number of the system matrix can be large. Therefore, the numerical solution is not an easy task and special procedures must be employed. Specifically, Gaussian elimination is avoided and advantageous use is made of the Householder transformation, in the light of the least-square nature of the problem and the discretized approach to the problem.Numerical results are presented. The effect of various system parameters (number of frequencies, number of directions, sampling time, number of sensors, and location of sensors) is investigated in connection with global or strong accuracy, local or weak accuracy, integral accuracy, and condition number of the system matrix.From the numerical experiments, it appears that the wave parameter identification problem has a unique solution if the number of directions is smaller than or equal to the number of sensors; it has an infinite number of solutions otherwise. In the case where a unique solution exists, the condition number of the system matrix increases as the size of the system increases, and this has a detrimental effect on the accuracy. However, the accuracy can be improved by proper selection of the sampling time and by proper choice of the number and location of the sensors.Generally speaking, the computations done for the discrete case exhibit better accuracy than the computations done for the continuous case (Ref. 5). This improved accuracy is a direct consequence of having used advantageously the Householder transformation and is obtained at the expense of increased memory requirements and increased CPU time.This work was supported by Exxon Production Research Company, Houston, Texas. This paper is based partly on Refs. 1–4.     

Moment information for probability distributions,without solving the moment problem,II: Main-mass,tails and shape approximation

How much information does a small number of moments carry about the unknown distribution function? Is it possible to explicitly obtain from these moments some useful information, e.g., about the support, the modality, the general shape, or the tails of a distribution, without going into a detailed numerical solution of the moment problem? In this, previous and subsequent papers, clear and easy to implement answers will be given to some questions of this type. First, the question of how to distinguish between the main-mass interval and the tail regions, in the case we know only a number of moments of the target distribution function, will be addressed. The answer to this question is based on a version of the Chebyshev–Stieltjes–Markov inequality, which provides us with upper and lower, moment-based, bounds for the target distribution. Then, exploiting existing asymptotic results in the main-mass region, an explicit, moment-based approximation of the target probability density function is provided. Although the latter cannot be considered, in general, as a satisfactory solution, it can always serve as an initial approximation in any iterative scheme for the numerical solution of the moment problem. Numerical results illustrating all the theoretical statements are also presented.     

On the mechanical and thermomechanical properties of low-density polyethylene/ethylene-α-octene copolymer blends

Blends of low-density polyethylene (LDPE) and ethylene-octene copolymer (EOC) were obtained. The effect of EOC content and absorbed radiation dose on the mechanical and thermomechanical properties of LDPE/EOC blends are investigated. Particular attention is given to a tensile stress-strain analysis and the “form-memory” effect of the blends. With growing LDPE content, the elastic modulus, the yield stress, and the thermorelaxation and residual stresses of the blends increase, but the ultimate elongation at break decreases, which is caused by the higher crystallinity of polyethylene. As a result of radiation-induced cross-linking, the elastic modulus, the yield stress (at a 1% strain), the ultimate yield strength, and the thermorelaxation and residual stresses increase, while the ultimate elongation at break and the melt flow-behavior index decrease, which is confirmed by the growing gel fraction in the blend. __________ Translated from Mekhanika Kompozitnykh Materialov, Vol. 44, No. 2, pp. 279–286, March–April, 2008.     

考虑成本、等待时间和安全水平的分类安检模式研究

近年来,随着民航机场旅客吞吐量快速增加,机场安检部门的工作压力正不断加大,旅客等待时间也正在逐渐增加。针对该问题,引入了分类安检模式。然而,分类安检模式通常需要额外的投资成本,可能会产生较大的财务负担。因此,以成本为目标,综合考虑旅客等待时间和安全水平的要求,研究了分类安检模式和传统安检模式的比较以及最优决策性质等相关问题。首先,考虑安全水平和旅客等待时间的约束,分别为传统安检模式和分类安检模式建立了模型,并分析了其最优运营决策性质。其次,从成本的角度,对两种安检模式做了比较研究。研究结果表明,当旅客数量多、安检犯错容忍度较高或旅客等待敏感时,分类安检模式比传统安检模式表现更优;反之,传统安检模式更优。此外,在分类安检模式中,分配到高风险安检通道的旅客比例存在一个最优值,并且其通常在20%到30%之间取到。最后,通过数值分析验证了分类安检模式的最优服务配置。     

绿色产品定价与市场入侵研究:基于市场权力结构的视角

为研究绿色产品定价与市场入侵问题,针对由两个制造商和一个零售商组成的系统,构建了制造商主导、零售商主导以及供需双方均势等三种权力结构模型,分析了权力结构、消费者绿色偏好等因素对绿色产品定价和市场入侵的影响。研究发现:绿色产品入侵市场存在可行条件,并且绿色产品市场入侵会导致普通产品制造商的利润损失;市场入侵对零售商有利,说明零售商会有动机引入绿色产品;绿色产品入侵市场和市场权力结构均会影响各个企业最优定价策略,其中拥有主导权的企业会选择高价策略;权力结构会影响供需双方的利润分配,以及导致系统利润的损失。