云南省珠心算教师培训班在普洱市举办

正2014年2月11日,云南省珠算心算协会在普洱市举办2014年度珠心算教师培训班,来自全省8个州市45名珠心算骨干教师参加了为期三天的培训。中国珠算心算协会秘书长王研玲出席开班仪式。     

2003年中国数学奥林匹克(CMO)在长沙举行

由中国数学会主办的 2 0 0 3年中国数学奥林匹克 (第 1 8届全国中学生数学冬令营 )于 2 0 0 3年1月 1 3日至 1 8日在湖南长沙举行 .本届冬令营的承办单位是长沙一中 ,这是第二次在中学举办ＣＭＯ ,第一次是去年在上海中学 .著名数学家陈省身教授、中国数学奥林匹克委员会主席王元院士都为本次活动题词 .来自内地、香港、澳门以及俄罗斯的共 36支代表队的 1 5 7名营员参加了活动 .经过两场比赛(每场 4个半小时、做 3道题 ) ,广东省代表队取得团体总分第一名 ,荣获“陈省身杯” .方家聪等 1 9名同学取得金牌 ,张凌人等 45名同学取得银牌 ,王蓉…     

提高45分钟数学课堂教学效率的实践与认识

当前,数学教育界对课堂教学中如何贯彻素质教育思想的问题正在进行各种讨论,素质一词反映在数学课堂中,应当包括数学素质和综合素质两个方面.学生的数学知识大多来自于课堂,学生的数学素质、学习数学的能力以及思维的品质更是在课堂的教学过程中逐步形成的,因此,扎扎实实地搞好数学课堂教学,切实提高数学课堂教学质量,使学生在数学课堂以外不再需要大量时间来学习数学,正是提高45分钟数学课堂教学效率的最佳体现.……     

何愿平：攻防兼备

何愿平喜欢踢足球。以前他喜欢踢前锋,现在却喜欢上了后卫。时光荏苒,何的职场定位也随他的球风而转,从最初的投资高手,转做攻防兼备的CFO。     

黑龙江省北安市杨家乡教委举办全乡数学教师珠算技术鉴定培训班

杨家乡教委,为了适应当代世界性教育思潮—素质教育的需要,提高全乡教师珠算技能素质,于1998年2月17日—2月23日,在乡中学电教室举办珠算技术鉴定培训班。 参加本次培训班的学员是来自全乡各小学幼儿园的数学教师、教导主任等,共45人。17日上午8点30分在电教室举行开班式。参加开班式的领导,有乡教委主任岳金才同志、副主任陈尔明、数学研究员陈玉尊等人。还特邀中珠协理事省珠协副秘书长、业务部     

珠算等级证书与实习推荐挂钩着眼于提高学生综合素质——访上海市南湖职业学校校长张云生

春雨淅沥,新芽吐青。穿过绿树婆娑的道路,登楼,采访上海市南湖职业学校校长张云生。上海市第三届"星光计划"中职技能大赛已降下帷幕。南湖职校138名学生参加28个项目的比赛,获得13项团体第一名,1项团体第二名,3项团体第三名,参赛学生获得45项个人全能一等奖,23项个人全能二等奖,37项个人全能三等奖,138名参赛学生     

北京交通大学理学院数学系

<正> 北京交通大学数学系始建于1986年,现有教师60余名,其中教授15名(含博士生导师8名),兼 职教授两名(含中国科学院院士一名),副教授30名,具有博士学位的教师30余名。     

有关两个三位数相乘的巧算

一、前两位相同、尾和10的巧算:前两位平方加前两位连上个位乘积例1458×452=452+45连上8×2=2025+45连上16=207,016例2826×824=822+82连上6×4=6724+82连上24=680,624     

绍兴文理学院数学系

<正> 绍兴文理学院数学系创建于1977年,现有数学与应用数学、信息与计算科学二个本科专业,其中数学与应用数学专业为校首批重点专业。计算数学为浙江省重点扶植学科,基础数学和应用数学为校级重点学科。本系拥有一支高素质、结构优化的教师队伍,现有教授8名,副教授22名,博士学位获得者5名,在读博士2名,硕士14名,有省、市级学科     

一道排列组合题的错解辨析

题目　要从8名男医生和7名女医生中选5人组成一个医疗小组.如果小组中至少要有男女医生各2名,有多少种不同的选法?这道题常见的解法是分类:一类男医生取2名,女医生取3名有Ｃ28Ｃ37种选法;另一类男医生取3名,女医生取2名有Ｃ38Ｃ27种选法.由加法原理共有Ｃ28Ｃ37 Ｃ38Ｃ27=2156种选法.这种解法无可非议,但学生提出下列解法:先取男、女医生各2名,有Ｃ28Ｃ27种取法,再从剩下的11名医生中取1名有Ｃ111种取法,由乘法原理,共有Ｃ28Ｃ37Ｃ111=6468种选法.上述解法为什么不对?错在哪里?辨析　把具体问题抽象化,用ａ1,ａ2,…,ａ8与ｂ1,ｂ2,…,ｂ7分别…     

Perturbation theory for the ground singlet state of the Heisenberg spin 1/2 antiferromagnetic chain

The Heisenberg spin 1/2 antiferromagnetic chain is considered. We use the perturbation theory where a collection of noninteracting clusters (chains with a small number of spins) is regarded as an unperturbed system and the interaction between clusters is regarded as a perturbation. The advantage of the perturbation theory is that it results in the proper thermodynamic limit. Expressions for corrections to the energy of the ground state of the chain are obtained up to the fourth order inclusive. The numerical results calculated for the infinite chain with the help of clusters containing 2, 4, 6, or 8 spins show good agreement with the exact value known from the Bethe ansatz. Bibliography: 9 titles. Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 224, 1995, pp. 14–35. Translated by I. V. Abarenkov.     

Integrated risk management for an electricity producer

Electricity suppliers face two sources of risk: uncertainty of spot prices and uncertainty of production costs. Uncertainty in selling the output is usually “solved” by signing forwards and the two sources of risk are dealt with separately. However, managing the integrated risk optimally is the direction we will suggest. We intend to analyse the problem a power producer is confronted to upon acting in a market where spot and forward agreements are available. Since forwards allow to sell production in advance at a given price but do not hedge against cost volatility, the total risk can be reduced by selling also in the spot market. The analysis is further detailed to encompass the spread option inherent in electricity production. We find a benchmark value for forwards to sign and the optimal spot/forward combinations. The analysis is carried out by accounting for market figures for input and output variables in the German market EEX.     

关于高等数学中极限思想的研究

本文针对在工科高等数学的教学中 ,学生对极限这一重要概念难以把握和理解的现象 ,提出了分三个层次并从哲学的角度来理解这一思想 ,为学生最终解决这一难点提供了一种有效的方法 .     

The non-Markovian approach to the valuation and hedging of European contingent claims on power with scaling spikes

We present and further develop a new approach to modeling power prices with spikes proposed earlier by the author. In contrast to other approaches, we model power prices with spikes as a non-Markovian stochastic process that allows for modeling spikes directly as self-reversing jumps. We show how this approach can be used to value European contingent claims on power with spikes as well as to value and dynamically hedge European contingent claims on forwards on power for power with spikes in a practically important special case of the scaling probability distribution for the magnitude of spikes.     

Approximation algorithm for the problem of partitioning a sequence into clusters

We consider the problem of partitioning a finite sequence of Euclidean points into a given number of clusters (subsequences) using the criterion of the minimal sum (over all clusters) of intercluster sums of squared distances from the elements of the clusters to their centers. It is assumed that the center of one of the desired clusters is at the origin, while the center of each of the other clusters is unknown and determined as the mean value over all elements in this cluster. Additionally, the partition obeys two structural constraints on the indices of sequence elements contained in the clusters with unknown centers: (1) the concatenation of the indices of elements in these clusters is an increasing sequence, and (2) the difference between an index and the preceding one is bounded above and below by prescribed constants. It is shown that this problem is strongly NP-hard. A 2-approximation algorithm is constructed that is polynomial-time for a fixed number of clusters.     

A Push Forward Construction and the Comprehensive Factorization for Internal Crossed Modules

In a semi-abelian category, we give a categorical construction of the push forward of an internal pre-crossed module, generalizing the pushout of a short exact sequence in abelian categories. The main properties of the push forward are discussed. A simplified version is given for action accessible categories, providing examples in the categories of rings and Lie algebras. We show that push forwards can be used to obtain the crossed module version of the comprehensive factorization for internal groupoids.     

A Simple Cluster Model for the Liquid–Glass Transition

Using the classical distribution-function approach to simple liquids, we estimate the orientational interaction between clusters consisting of a particle and its nearest neighbors. We show that there are density and temperature ranges where the interaction changes sign as a function of the cluster radius. On this basis, the corresponding model of interacting cubic and icosahedral clusters (of the type of a spin glass model) is proposed and solved in the replica-symmetric approximation. We show that the glass order parameter grows continuously on cooling and the replica-symmetry-breaking temperature can be identified with the glass transition temperature. We also show that on cooling a system of particles with a Lennard-Jones interaction, cubic clusters freeze first. The transition temperature for icosahedral clusters is somewhat lower; therefore, the cubic structure of the short-range order is more likely in a Lennard-Jones glass near transition.     

On the definition of singular bilinear forms and singular linear operators

We analyze various definitions of the concepts of a singular operator and a singular bilinear form and propose the most suitable ones. We also study the simplest properties of these objects.Published in Ukrainskii Matematicheskii Zhurnal, Vol. 45, No. 8, pp. 1084–1089, August, 1993.     

On the Evolution of Large Clusters in the Becker-D?ring Model

Summary. We consider the Becker-D?ring equations for large times. It is well-known [2] that if the total density of monomers exceeds a critical value, the excess density is contained in larger and larger clusters as time proceeds. We rigorously derive for general coefficients that the evolution of these large clusters is described by a nonlocal transport equation, which is for specific coefficients the classical coarsening model by Lifshitz, Slyozov, and Wagner (LSW). Our proof exploits the estimate of the energy and the energy dissipation rate given by the Lyapunov functional for the Becker-D?ring equations. We also provide a detailed asymptotic expansion of the higher-order dynamics.     

Resonance expansions of propagators in the presence of potential barriers

We show that the Schrödinger propagator can be expanded in terms of resonances at energy levels at which a barrier separates the interaction region from infinity. The expansions hold for all times with errors small in the semi-classical parameter. As a byproduct we obtain a result on the approximation of clusters of resonant states by clusters of eigenfunctions of a self-adjoint reference operator.