双符号等长代换系统的序列熵

系统称为null的,如果对任意序列,它的序列熵为零.双符号等长代换及其对应的代换极小系统可分成三类:有限的、离散的和连续的.容易看出离散的代换极小系统是null的,Goodman证明了连续的代换极小系统不是null的.本文将完全刻画所有的双符号等长代换极小系统的序列墒.     

代换序列研究概况

代换序列的研究可追溯到Thue在1906年的工作,在这一工作中,他引入了一个由代换生成的序列(现称为Thue-Morse序列),研究了它的组合性质,给出了若干非重复序列的例子.大半个世纪以来,人们在各个不同的领域的研究中,从各个不同的角度一再地引入该序列并且不断地加以推广,从而引起了对一般的代换序列的研究.在六十和七十年代,这种研究主要集中在与动力系统和自动机理论的联系及其应用上.八十年代以来,人们相继发     

Fengenbaum映射的搓揉序列与特征集

设f为Feigenbaum映射,亦即函数方程fp(λx)=λf(x)满足一定条件的单峰解．f的搓揉序列为0-1无限序列,f的特征集是临界点轨迹的闭包．本文研究f的性质进而证明．f的搓揉序列是某代换在符号空间中的不动点,f在特征集上的限制是某代换子移位的一个因子．     

两个符号的等长代换子系统的混沌性态

本文研究了由两个符号的等长代换生成的子系统的混沌性态．通过分类研究,我们得到：（1）非奇异代换系统不是Li－Yorke混沌的,作为特例,Morse极小系统不是混沌的;（2）奇异代换子系统都是Li－Yorke混沌的．     

通过由代换序列生成的一维链的绝缘性

本文建立了平面波ｅ＾－ｉｋｘ通过势ｕＮ（ｘ）＝ＮΣｎ＝１ｖｎδ（ｘ－ｘｎ），Ｎ→＋∞时系统的透射振幅和反射振幅的递推公式；给出系统为绝缘体的充要条件；最后，找出了判断由代换序列生成的一类一维链系统为绝缘体的方法。     

基于列随机矩阵的逐次差分代换与正半定型的机械化判定

本文选择列随机平均矩阵T_n作为基本代换矩阵,建立了基于T_n的逐次差分代换方法.获得了R_+~n上正半定型,不定型判定的充要条件.并进一步证明了:正定型的差分代换集序列正向终止.根据这些结果编写的Maple程序TSDS3,能够自动证明代数型不等式,对不成立的不等式总能输出反例.该程序虽可能不停机,但大量的应用实例证实了该方法的实用性.     

差分代换矩阵与多项式的非负性判定

主要分析了差分代换矩阵的基本性质,证明了存在有限个差分代换矩阵的乘积可以将单位点$(1,0,\cdots,0)$变换到指定的非负(本原)整点.利用这一结果可以导出${R^n_+}$上判定半正定型的充要条件.根据此充要条件建立的算法(TSDS)可能不停机,针对不停机的情况,再给出一些判定半正定型的充分条件.     

均值代换和不等式的证明

设ｘ≥ 0 ,ｙ≥ 0 .作为算术平均———几何平均不等式Ａ ≥Ｇ的应用 ,我们把代换Ａ =ｘ ｙ2Ｇ =ｘｙ叫做均值代换 .在这样的代换下有 :ｘ ｙ =2Ａ ,ｘｙ=Ｇ2 ,(ｘ -ｙ) 2 =4Ａ2 - 4Ｇ2 =4(Ａ Ｇ) (Ａ-Ｇ)ｘ2 ｙ2 =4Ａ2 - 2Ｇ2 =2 (2Ａ2 -Ｇ2 )ｘ3 ｙ3=8Ａ3- 6ＡＧ2 =2Ａ(4Ａ2 - 3Ｇ2 )……由于ｍａｘ(ｘ ,ｙ)≥Ａ≥Ｇ≥ｍｉｎ(ｘ ,ｙ) ≥ 0 ,因此应用均值代换法证不等式特别利于放缩 ,能起化难为易的作用 ,收事半功倍的效果 .例 1　 (美国纽约 ,1 975 )证明 ,对任意正数ａ≠ｂ之算术平均值Ａ=ａ ｂ2 与几何平均值Ｂ=ａｂ ,有Ｂ <(ａ-ｂ) …     

一道反常积分题的多种解法

分别运用有理函数积分法、倒代换以及三角代换三种方法,计算反常积分∫0+∞1/(1+x)(1+x2.)dx     

在SAS系统方差分析过程中作统计代换

本文介绍了ＳＡＳ系统中方差分析过程的四种统计代换方法，即增殖率代换、反正弦角度代换、平方根代换及对数代换，并以实例示明ＳＡＳ程序中的具体代换方法。这些方法在ＳＡＳ系统中是颇具实用价值的     

Inverse nodal problem for p–laplacian dirac system

In this study, we solve an inverse nodal problem for p‐Laplacian Dirac system with boundary conditions depending on spectral parameter. Asymptotic formulas of eigenvalues, nodal points and nodal lengths are obtained by using modified Prüfer substitution. The key step is to apply modified Prüfer substitution to derive a detailed asymptotic estimate for eigenvalues. Furthermore, we have shown that the functions r(x) and q(x) in Dirac system can be established uniquely by using nodal parameters with the method used by Wang et al. Obtained results are more general than the classical Dirac system. Copyright © 2016 John Wiley & Sons, Ltd.     

Incentive and production decisions for remanufacturing operations

We consider a manufacturer producing original products using virgin materials and remanufactured products using returns from the market where the amount of returns depend on the incentive offered by the manufacturer. We determine the optimal value of this incentive and the optimal production quantities in a stochastic demand setting with partial substitution. We analyze 3 different models in centralized and decentralized settings where the collection process of the returns is managed by a collection agency in the decentralized setting. We also analyze contracts to coordinate the decentralized systems and determine the optimal contract parameters. Finally, we present our computational study to observe the effect of different parameters on the system performance.     

Substitution systems and the three versions of distributional chaos

There are three types of distributional chaos, namely DC1, DC2 and DC3. In this paper we present two constant-length substitution systems, one is DC2 but not DC1, and the other is DC3 but not DC2. (In this paper, chaos means existence of an uncountable scrambled set of the corresponding type while the existing examples deal with single pairs of points only.)     

Limit theorems for random processes with random time substitution

In this paper we prove a theorem on sufficient conditions for the convergence in the Skorokhod space D[0, 1] of a sequence of random processes with random time substitution. We obtain almost sure versions of this theorem.     

带有共振的二阶哈密顿系统非平凡解的存在性

本文研究二阶哈密顿系统的非平凡解问题.假设系统中的非线性项V′是渐近线性的.利用变分法,通过系统对应泛函的小扰动的临界点来建立系统的Palais-Smale序列,进而说明该序列的有界性.与一般做法不同的是,本文对V′不限定Landesman-Lazer条件.     

Invertible substitutions and Sturmian sequences

It is known on the one hand that a Sturmian sequence can be generated geometrically by the intersections of a straight line with the unit grid in the plane, and on the other hand that fixed points of invertible substitutions are Sturmian. We give a new characterization of invertible substitutions, which allows to determine the straight line which generates the fixed point of a given invertible substitution.     

Evaluation of inventory policies with unidirectional substitutions

We propose evaluation approaches to multi-item base-stock inventory policies where unidirectional substitutions are allowed. The problems in the paper are in the context of spare parts management and we identify two substitution cases: substitution upon demand arrivals and substitution upon order deliveries. This leads us to three unidirectional substitution policies, for each of which we develop Markovian models. As the number of part types increases, computational effort required to solve the Markovian models increases rapidly. To reduce computation burden, an approximation approach based on the decomposition of multi-dimensional state transition is used for systems with two or more spare part types. Numerical studies show unidirectional substitution improves various system performance measures such as the average inventory level, the average backlogged demand, and the fill rate. The proposed decomposition approach reduces the computation required to compute the performance measures and the approximation errors seems to be quite small.     

外部市场存在替代产品的VMI系统研究

供应商管理用户库存(VMI)作为一种有效的补货机制,能对购买渠道的需求信息做出积极正确的反应.现在对VMI的研究往往集中于单个零售商和单个供应商组成的系统,不考虑VMI系统受市场上其他零售商或供应商的影响.假设市场上多个零售商出售相互之间可替代的产品,某个零售商与其供应商之间应用VMI系统.我们的研究主要有两方面:1)VMI系统是否有助于零售商和供应商组成的供应链在差异产品市场上获得更大的收益;2)供应商和零售商如何决策是否应用VMI系统。