Hamiltonian[k,k+1]-因子

本文考虑n/2-临界图中Hamiltonian[k,k+1]-因子的存在性。Hamiltonian[k,k+1]-因子是指包含Hamiltonian圈的[k,k+1]-因子;给定阶数为n的简单图G,若δ(G)≥n/2而δ(G\e)相似文献   

Smarandache函数在两数列上的下界估计

设S(n)是Smarandache函数,其中n是一正整数.讨论Smarandache函数S(n)在数列F((2k),1)=F(n,1)=n2n+1(n=2k)与数列G(2n,1)=(2n)2n+1上的下界估计.基于初等方法证明了:当偶数n≥6时,有S(F((2k),1))=S(F(n,1))≥6×2n+1;当n≥4时,有S(G(2n,1))≥6×2n+1.     

退化(K_1,K_2)拟正则映射的充分条件

研究了退化弱(k1,k2)拟正则映射的正则性.利用H lder不等式、Sobolev空间的空间分析方法,以及内插定理等工具,给出了退化弱(k1,k2)拟正则映射事实上为退化(k1,k2)拟正则映射的一个充分条件,其结果对非退化情形也成立.     

退化（k1，k2）拟正则映射的充分条件

研究了退化弱（k1,k2）拟正则映射的正则性．利用Holder不等式、Sobolev空间的空间分析方法,以及内插定理等工具,给出了退化弱（k1,k2）拟正则映射事实上为退化（k1,k2）拟正则映射的一个充分条件,其结果对非退化情形也成立．     

典型群PSU（3，q2）与2—（v,k,1）设计

讨论自同构群是酉群PSU（3,q2)(q=2^l)的区－本原的2-(v,k,1)设计,首先证明了它必是点－本原的,然后确定了这种类型的设计,即它只能为2－（q3 1,q 1,1)设计。     

由平面方向决定的新型行列式

设F是一个域.任给F中的一对元素(k1,k2),给出了(k1,k2)-型行列式的定义.我们指出通常的行列式恰是(1,-1)-型.研究了这些(k1,k2)-行列式的性质,指出和通常行列式的相同和不同之处.刻画了一些特殊的(r,-r)-型,(r,0)-型和(r,r)-型行列式的性质.     

一类（k＋1）-色有向图的本原指数

本文定义了一类具有(k+1)-色(k+1)-圈的有向图D(A),得到了它本原的充要条件,并给出了它的本原指数.     

(G~(k+1)/G~k)展开法以及KdV方程的行波解（英文）

本文中,(G(k+1)/G(k))展开法被首次提出,其中k为非负整数,并且G=G(ξ)满足k+2阶常系数齐次线性微分方程(LODE),同时给出表达式(G(k+1)/G(k))的解析公式,并由此得到非线性发展方程的双曲函数解、有理函数解及三角函数周期解,最后给出一个利用(G(k+1)/G(k))展开法求解KdV方程的实例.     

四面体的k号心及其性质

本文拟用解析法 ,建立四面体的 k号心的概念 ,并研究它的性质 .定义 1　在空间任取一点 P,以 P为原点建立空间直角坐标系 ,设四面体 A1A2 A3 A4的顶点 Ai 的坐标为 (xi,yi,zi) (i=1,2 ,3,4 ) ,对非零实数 k,令x′=1k 4i=1xi,y′=1k 4i=1yi,z′=1k 4i=1zi,则点 Q(x′,y′,z′)称为四面体 A1A2 A3 A4关于点 P的 k号心 .显然 ,四面体关于点 P的 4号心就是四面体的重心 .定理 1　设四面体 A1A2 A3 A4关于点 P的 k号心为 Q,其重心为 G.则 Q,G,P三点共线 ,且 G分有向线段 QP所成的比为 (4 - k) / k.证　应用同一法 .在有向线段 QP…     

J_(*,k)~(2~k+2~(k-1))的结构

本文通过构造上协边环MO*的一组生成元决定了J*,k2k+2k-1．     

Two-dimensional modelling of the river Rhine

The system for operational water level forecast and prediction of (fortunately not daily) pollutant transport for the river Rhine is in daily use. This model is based on the Saint-Venant or one-dimensional shallow water equations.The model is augmented by additional terms and equations to model the effect of dead zones and the transport of soluble components.The next step is to move towards two-dimensional models. An important problem that arises is that the domain of the fluid is not fixed by the given data, but depends on the water level and is therefore part of the solution of the model. Even worse, depending on the topography of the river bed, even the topology of the fluid domain may change, as islands may appear at low water and get flooded at high water situations.     

A plethora of three-dimensional periodic travelling gravity-capillary water waves with multipulse transverse profiles

This article presents a rigorous existence theory for three-dimensional gravity-capillary water waves which are uniformly translating and periodic in one spatial direction x and have the profile of a uni- or multipulse solitary wave in the other z. The waves are detected using a combination of Hamiltonian spatial dynamics and homoclinic Lyapunov-Schmidt theory. The hydrodynamic problem is formulated as an infinite-dimensional Hamiltonian system in which z is the timelike variable, and a family of points P_k,k+1, k = 1,2,... in its two-dimensional parameter space is identified at which a Hamiltonian 0²0² resonance takes place (the zero eigenspace and generalised eigenspace are respectively two and four dimensional). The point P_k,k+1 is precisely that at which a pair of two-dimensional periodic linear travelling waves with frequency ratio k:k+1 simultaneously exist (Wilton ripples). A reduction principle is applied to demonstrate that the problem is locally equivalent to a four-dimensional Hamiltonian system near P_k,k+1. It is shown that a Hamiltonian real semisimple 1:1 resonance, where two geometrically double real eigenvalues exist, arises along a critical curve R_k,k+1 emanating from P_k,k+1. Unipulse transverse homoclinic solutions to the reduced Hamiltonian system at points of R_k,k+1 near P_k,k+1 are found by a scaling and perturbation argument, and the homoclinic Lyapunov-Schmidt method is applied to construct an infinite family of multipulse homoclinic solutions which resemble multiple copies of the unipulse solutions.     

Pm‖Cmax问题的算法AKK的一个改进的最坏情况性能比

本文考虑的是平行机排序问题Pm‖Cmax.对此问题Knuth和Kleitman给出了一个近似算法AKK,Graham证明了此算法的最坏情况性能比不大于1＋1-1/m/1＋｜k/m｜,而且当k≡0（modm）时这个界是紧的.在本文中我们给出了此算法的一个改进的最坏情况性能比： 1＋max{1-1/m/1＋k1＋1/m,1-1/m-k2/1＋k1},其中k1和k2为非负整数且k1m＋k2=k.本文证明了当k2≠0时,它好于Graham的结果,同时我们给出了两个实例说明这个界是紧的.     

Operational scheduling of refined product pipeline with dual purpose depots

Pipelines are one of the most economic and safe ways to transport oil derivatives to depots near the local markets. This is so, especially when there is a need for carrying a huge amount of petroleum products to long distance points. A pipeline may connect several refineries and depots where the connected points are able to inject products or receive them, or both (dual purpose depots). The main point of pipeline scheduling is to identify an optimal sequence of batches that satisfy demand with minimum costs. This paper presents an MILP continuous formulation for pipeline scheduling. The proposed model results in the reduction of problem size with respect to available models, and increases the accuracy. Computational results and data are reported.     

A decisional procedure for water resources planning taking into account water quality constraints

This paper describes an approach for water resources planning taking into account both quantity and quality aspects. A decisional procedure is proposed which consists of two phases. In the first phase, the water resources sharing problem is dealt with, taking into account the demands of the various water users and the requirement of a minimum flow in any section of the river. In the second phase, the problem of fulfilling water quality standards is considered. This may require to reformulate the water resources sharing problem in order to increase the water flow in the river.     

Optimal control with a quadratic criterion in distributed gas-transport systems

On the basis of the method of generalized Lagrange multipliers we obtain optimality conditions in the problem of tracking a given variation in regime of a distributed pipeline gas transport system with an integral quadratic quality criterion. We propose a method and an algorithm for finding optimal controlling actions. We present the results of computation of optimal controls in a homogeneous pipeline. Translated fromDinamicheskie Sistemy, Vol. 11, 1992.     

On Perturbed Discrete Boundary Value Problems

In this paper, we study nonlinear discrete boundary value problems of the form x ( t +1)= A ( t ) x ( t )+ h ( t )+ k f ( t , x ( t ), k ) subject to Bx (0)+ Dx ( J )= u + k g ( x (0), x ( J ), k ) where k is a "small" parameter. Our main concern is the case of resonance, that is, the situation where the associated linear homogeneous boundary value problem x ( t +1)= A ( t ) x ( t ), Bx (0)+ Dx ( J )=0 admits nontrivial solutions. We establish conditions for the solvability of the nonlinear boundary value problem when k is "small". We also establish qualitative properties of these solutions.     

n阶时滞差分方程的边值问题

本文研究ｎ阶时滞差分方程的边值问题：ｘ（ｋ＋ｎ）＝ｆ（ｋ，ｘｋ（），ｘ（ｋ），ｘ（ｋ＋１），…，ｘ（ｋ＋ｎ－１）），ｋ∈ＩＴ，ｘ（ｍ）＝φ（ｍ），ｍ∈Ｉ－ｒ，ｘ（１）＝ａ１，ｘ（２）＝ａ２，…，ｘ（ｎ－２）＝ａｎ－２，ｘ（Ｔ）＝Ａ，｛得到了解的存在性和唯一性的结果．     

平面图的Alcuin数

广义渡河问题是一类重要的组合优化问题,它是经典的狼-羊-卷心菜游戏的推广。冲突图是一个图,这个图的任意两个点所代表的物品不相容时(例如,狼和羊代表的物品不相容),则在这两个点之间连结一条边。渡河覆盖问题的目的是确定冲突图全部点所代表的物品从河的一岸安全地摆渡到河的对岸时所需船的最小容量,而冲突图的Alcuin数定义这个最小容量。本文讨论了平面图的Alcuin数, 给出了该类图Alcuin数的完全刻画。