通法不“宜”,以“巧”制胜

<正>数学解题中,有些选择、填空题,使用通法解答常常繁杂冗长,难以凑效,不适宜,但巧做,能使思路新颖,方法精巧,步骤简洁,表达干净利落,往往起到删繁就简,变难为易之功效.既赢得了时间,又保存了精力,优化了思维     

Poisson Stable Solutions for Stochastic Differential Equations with Lévy Noise

In this paper,we use a unified framework to study Poisson stable(including stationary,periodic,quasi-periodic,almost periodic,almost automorphic,Birkhoff recurrent,almost recurrent in the sense of Bebutov,Levitan almost periodic,pseudo-periodic,pseudo-recurrent and Poisson stable)solutions for semilinear stochastic differential equations driven by infinite dimensional L′evy noise with large jumps.Under suitable conditions on drift,diffusion and jump coefficients,we prove that there exist solutions which inherit the Poisson stability of coefficients.Further we show that these solutions are globally asymptotically stable in square-mean sense.Finally,we illustrate our theoretical results by several examples.     

璀璨的鄂东名校——湖北省浠水实验高中掠影

浠水县实验高中坐落在环境优美的县城东北风景秀丽的凤栖山上。这里区位优良,交通便捷,东邻闻一多纪念馆,南望京九铁路和沪蓉高速公路,西邻大广北高速公路。登高俯瞰,浠河水色、熊湖新貌、一多馆景,让人赏心悦目,新华正街一派繁荣景象尽收眼底。学校历史底蕴丰厚,王羲之曾至此泼墨挥毫,苏东坡题笔凤栖石墨迹尚存,现代大儒徐复观先生曾托忠魂于此,汤佩松院士为生物园题写园名。校内绿树成荫,花香四季,道路蜿蜒,     

会长张弘力在中国珠算心算协会第八届会员大会上的讲话

刚才,大家推选我为中国珠算心算协会第八届理事会会长,我感到十分荣幸,感谢财政部党组和各位理事对我的信任。与此同时,也深感责任重大,珠算心算对我而言,是陌生的全新的领域,担任这一领域如此重要的职务,既是莫大的荣誉,也是巨大的挑战,我将珍惜这一荣誉,竭尽全力,与各位理事、各位会员一道,并在你们的支持和帮助下,去迎接挑战。     

会长张弘力在中国珠算心算协会第八届会员大会上的讲话（2014年7月20日）

刚才,大家推选我为中国珠算心算协会第八届理事会会长,我感到十分荣幸,感谢财政部党组和各位理事对我的信任。与此同时,也深感责任重大,珠算心算对我而言,是陌生的全新的领域,担任这一领域如此重要的职务,既是莫大的荣誉,也是巨大的挑战,我将珍惜这一荣誉,竭尽全力,与各位理事、各位会员一道,并在你们的支持和帮助下,去迎接挑战。     

每次进步一点点,奇迹就会发生

香港海洋公园里有一条大鲸鱼,虽然重达8600 kg,却不但能跃出水面6.6m,还能向游客表演各种杂技.面对这条创造奇迹的鲸鱼,有人向训练师请教训练的秘诀.训练师说,在最初开始训练时,我们会先把绳子放在水面之下,使鲸鱼不得不从绳子上方通过,每通过一次,鲸鱼就能得到奖励.渐渐地,我们会把绳子提高,只不过每次提高的幅度都很小,大约只有2 cm,这样鲸鱼不需花费多大的力气就有可能跃过去,并获得奖励.于是,这条常常受到奖励的鲸鱼,便很乐意地接受下一次训练.随着时间的推移,鲸鱼跃过的高度逐渐上升,最后竟然达到了6.6m.     

PROPERTIES OF SOME SETS OF SEQUENCES DEFINED BY A MODULUS FUNCTION

In this article, the author introduces the generalized difference paranormed sequence spaces c （△v^m, f, p, q, s）, c0 （△v^m, f, p, q, s）, and l∞ （△v^m, f, p, q, s） defined over a seminormed sequence space （X, q）. The author also studies their properties like completeness, solidity, symmetricitv, etc.     

2010年名校自主招生数学试题赏析

2010年高校自主招生数学试题总的来说,除五校联考（清华大学,上海交大,中国科技大学,南京大学,西安交大）试题较难之外,其他几所名校,如：北京大学,复旦大学,浙江大学,南开大学数学特长班等校试题难度比较适中．下面,我们对今年各名校自主招生试题作一归纳并选出部分试题作一赏析．     

封面人物介绍

余锦银男,湖北省黄石市有突出贡献专家,省教育厅教研培训专家组成员,湖北阳关教育研究院专家,省优秀数学教师,省、市优质课比赛双冠军,省优秀主讲专家,全国教科研先进个人,中国数学会会员.已在     

1和0

正1和0是一对非常要好的朋友。有一天,吃过晚饭,1和0相约到河边散步。他们手拉手,一边走,一边聊,来到一座独木桥前。忽然,两个人的嗓门都大了起来,他们吵架了!1说:"我们认识那么多年了,怎么说,我也比你大,当然是我先过河!"0马上表示反对:"排队的时候,我总是排在你前面,当然是我先过河!"1听了,非常不服气:"我肚子里有货色,你却肚子空空,什么都     

Milnor方图中的w-凝聚性

整环R称为ω-凝聚整环,是指R的每个有限型理想是有限表现型的.本文证明了ω-凝聚整环是v-凝聚整环,且若(RDTF,M)是Milnor方图,则在Ⅰ型情形,R是ω-凝聚整环当且仅当D和T都是ω-整环,且T_M是赋值环;对于Ⅱ-型情形,R是ω-凝聚整环当且仅当D是域,[F:D]<∞,M是R的有限型理想,T是ω-凝聚整环,且R_M是凝聚整环.     

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At present, in degradation tests, product failure is generally defined as degradation of performance below or above a specified critical value (that is called single point degradation). Although this definition is simple and practical, it is not reasonable enough and degradation failure of the product can not be completely described. In this paper, a single point degradation model is improved, and an interval degeneration model is proposed. We discuss the interval degradation model when the degradation path is liner, and obtain life distribution functions for all kinds of linear interval degradation model. Numerical integration and Monte Carlo simulation methods are used to analyze and compare the life distribution of the interval degradation model and the single point degradation model, and the relationship between the interval degradation and the single point degradation is revealed. Finally, an real data example is analysis to show that interval egradation is more reasonable and effective in practice.     

沪深股市收益的相关性

以概率作为相关度量指标,分整体相关性和尾部相关性对沪深两市收益进行考察。整体相关性采用概率方法中的变化协调形成的相关性作为度量,结果表明沪深两市收益在整体上具有一定的正相关性。对于尾部相关性,先用t分布分别拟事两市收益底分布,然后用蒙特卡洛模拟确定尾部的最优门限,进而求得尾部相关性,结果显示当市场剧烈波动时两市收益具有正的相关性,且比整体相关性强,尤其在暴跌的时候,两市具有很强的正相关性。     

油田注水系统拓扑布局优化的混合遗传算法

以投资最小为目标函数,建立了注水系统拓扑布局优化数学模型.根据模型特点,将优化问题分为两层,分别采用遗传算法和非线性优化方法进行求解.并对遗传算法的操作过程进行了改进,调整了适应函数,改进了交叉和变异操作,结合了模拟退火算法,在操作过程中使约束条件得到满足,减少了不可行解的产生,使遗传算法的优化性能得到了提高.优化算例说明了该方法的有效性.     

An Improved Branch & Bound Method for the Uncapacitated Competitive Location Problem

In this paper, the problem of locating new facilities in a competitive environment is considered. The problem is formulated as the firm expected profit maximization and a set of nodes is selected in a graph representing the geographical zone. Profit depends on fixed and deterministic location costs and, since customers are independent decision-makers, on the expected market share. The problem is an instance of nonlinear integer programming, because the objective function is concave and submodular. Due to this complexity a branch & bound method is developed for solving small size problems (that is, when the number of nodes is less than 50), while a heuristic is necessary for larger problems. The branch & bound is called data-correcting method, while the approximate solutions are obtained using the heuristic-concentration method.     

Compromise solutions and estimation of the noninferior set

A general framework is presented in which the relation of the set of noninferior points and the set of compromise solutions is studied. It is shown that the set of compromise solutions is dense in the set of noninferior points and that each compromise solution is properly noninferior. Also, under convexity of the criteria space, a characterization of the properly noninferior points in terms of the compromise solutions is presented. In this characterization, the compromise solutions depend continuously on the weights. Use of the maximum norm is studied also. It is shown that a subset of these max-norm solutions, obtained by taking certain limits of compromise solutions, is dense and contained in the closure of the set of noninferior points.     

两类带有确定潜伏期的SEIS传染病模型的分析

通过研究两类带有确定潜伏期的SEIS传染病模型,发现对种群的常数输入和指数输入会使疾病的传播过程产生本质的差异．对于带有常数输入的情形,找到了地方病平衡点存在及局部渐近稳定的阈值,证明了地方病平衡点存在时一定局部渐近稳定,并且疾病一致持续存在．对于带有指数输入的情形,发现地方病平衡点当潜伏期充分小时是局部渐近稳定的,当潜伏期充分大时是不稳定的．     

Chaotic synchronization with filter based on wavelet transformation

A kind of chaotic synchronization method is presented in the paper. In the transmitter, part signals are transformed by wavelet and the detail information is removed. In the receiver, the component with low frequency is reconstructed and discrete feedback is used, we show that synchronization of two identical structure chaotic systems is attained. The effect of feedback on chaotic synchronization is discussed. Using the synchronous method, the transmitting signal is transported in compressible way, system resource is saved, the component with high frequency is filtered and the effect of disturbance on synchronization is reduced. The synchronization method is illustrated by numerical simulation experiment.     

Banach空间有界线性算子强连续双半群

本文在Ｂａｎａｃｈ空间上研究单参数有界线性算子族－强连续双半群。     

基于韧性度的低轨卫星通信网络抗毁性度量及优化

低轨卫星通信网络的抗毁性是描述网络安全可靠的有效工具,在网络体系结构设计和路由策略等领域得到了广泛的应用。根据低轨卫星通信网络中卫星在轨道平面内移动,需要不断进行切换的特点,从建立抗毁性测度模型以及网络抗毁性优化两个角度来评估和提高网络抗毁性,提出一种基于韧性度的低轨卫星通信网络抗毁性度量方法。通过对移动模型以及切换模型的结构分析,对每种结构以一定概率出现的低轨卫星通信网络,应用韧性度函数,求得网络在某个时刻及某一段时间段内的抗毁性,并针对切换模型的不足之处进行优化,用赋权韧性度来体现优化的效果,得到了优化后的网络抗毁性。以铱星系统为应用实例进行仿真,结果表明:任意时刻网络的抗毁性跟拓扑结构的韧性度值有关,并且是一种线性关系,即随着韧性度的增加,其抗毁性也增加。通过对铱星通信系统切换模型的优化,网络的抗毁性与平均抗毁性都得到了提升,说明本文所构建模型的有效性和实用性。