Monotone methods for a discrete boundary problem

This paper is motivated by recent interests in space discrete Nagumo equations and is concerned with the existence of solutions of a nonlinear discrete boundary value problem. Monotone methods are used to derive the existence theorems. These methods, as is well known, provide constructive schemes for calculating the solutions.     

网络环境下思想政治教育探讨

本文阐述了网络的主要特点以及网络环境下思想政治教育工作目前存在的主要问题,并在文后给出了网络环境下思想政治教育工作的对策。     

Monotone and numerical-analytic methods for differential equations

The method of lower and upper solutions combined with monotone iterative techniques is used for ordinary differential equations with integral boundary conditions showing the existence of extremal solutions. Some existence results are also formulated using the numerical-analytic method. Sufficient conditions for existence are given.     

On the existence,uniqueness and nature of Carathéodory and Filippov solutions for bimodal piecewise affine dynamical systems

In this paper, we deal with the well-posedness (in the sense of existence and uniqueness of solutions) and nature of solutions for discontinuous bimodal piecewise affine systems in a differential inclusion setting. First, we show that the conditions guaranteeing uniqueness of Filippov solutions in the context of general differential inclusions are quite restrictive when applied to bimodal piecewise affine systems. Later, we present a set of necessary and sufficient conditions for uniqueness of Filippov solutions for bimodal piecewise affine systems. We also study the so-called Zeno behavior (possibility of infinitely many switchings within a finite time interval) for Filippov solutions.     

A polyhedral approach to solving multicriterion combinatorial optimization problems over sets of polyarrangements

Multicriterion discrete optimization problems over feasible combinatorial sets of polyarrangements are considered. Structural properties of feasible domains and different types of efficient solutions are investigated. Based on the ideas of Euclidean combinatorial optimization and the major criterion method, a polyhedral approach to the solution of the problems is developed and substantiated. Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 118-126, May-June 2009.     

Running focus groups with elderly and disabled elderly participants

This paper is based on a study to determine the information needs of elderly, disabled elderly people, and of their carers, in the UK. Four focus groups were run with a total of 20 participants to identify major themes and aid in the creation of a questionnaire for a national survey. This paper does not describe the findings of the focus groups but reports on the lessons learned from running them, in the light of the increasing importance of such methods. A number of difficulties arose, most associated with age-related declines in sensory, perceptual, cognitive and communication abilities. These difficulties are described, together with the steps that need to be taken to eliminate, or at least ameliorate, them, so that this powerful method of collecting information can be used fruitfully on elderly and disabled elderly people.     

Resonant soliton and complexiton solutions for (3+1)-dimensional Boiti–Leon–Manna–Pempinelli equation

In this letter, the linear superposition principle is used to discuss the $(3+1)$-dimensional Boiti–Leon–Manna–Pempinelli equation with bilinear derivatives. As a result, we obtain new resonant soliton and complexiton solutions by discussing two different cases involved the parameters. These solutions are a class of $N$-wave solutions of linear combinations of exponential traveling waves.     

Distributions of the potential and electric field of an electrode elliptic array used in tumor electrotherapy: Analytical and numerical solutions

To estimate the potential and electric field generated by any electrode array is very useful in effective tumor destruction. At present, an electrode array that takes into account the ellipsoidal geometry of the solid tumors has not been proposed. We present both analytical and numerical solutions for the potential and electric field in a solid tumor established by an electrode array with elliptic shape which may be used in vitro, in vivo and in clinical studies for cancer treatment with electrotherapy. These analytical and numerical solutions are obtained using multipole expansion and the finite difference method. Distributions of potential and electric field magnitudes are computed in function of the eccentricity of an elliptical array and compared with those obtained with a circular array of electrode. Maximum difference and Root Means Square Error are used to compare the distributions of the potential and electric field in leading-order and first-order correction and between the analytical and numerical solutions. The results show a good agreement between these distributions in both orders and the analytical and numerical solutions. It was concluded that the mathematical approach presented in this study is a tool for a rapid design of electrode elliptical arrays in order to induce the maximum destruction of the tumor. Moreover, it is shown that, for all values of eccentricity, there is a good correspondence between the distributions of the potential and the electric field for leading-order and first-order correction and for both the analytical and numerical solutions.     

具有不确定参数多目标决策的一类鲁棒有效解

针对具有区间型不确定参数多目标决策问题,探讨了决策人在决策的最优性与决策后果 的不确定性之间的权衡,从而制定决策的方法,提出了鲁棒有效解及ε-鲁棒有效解的概念,并研究 了其最优性条件.     

Exact wave solutions for a (3+1)-dimensional generalized B-type Kadomtsev–Petviashvili equation

In this work, we investigate a (3+1)-dimensional generalized B-type Kadomtsev–Petviashvili equation. Based on the simplified Hirota bilinear method, we first construct its soliton solutions. Meanwhile, we correct the formula of N-soliton solution for this equation. On the basis of these solitons we further calculate its lump solutions, periodic waves. Meanwhile, rogue waves as well as interaction solutions of this equation are also obtained by a direct algebraic method. Some figures are given to display the behavior of these solutions.     

Suboptimal and optimal order policies for fixed and varying replenishment interval with declining market

One of the supply chain risks for hi-tech products is the result of rapid technological innovation; it results in a significant decline in the selling price and demand after the initial launch period. Hi-tech products include computers and communication consumer's products. From a practical standpoint, a more realistic replenishment policy is needed to consider the impact of risks; especially when some portions of shortages are lost. In this paper, suboptimal and optimal order policies with partial backordering are developed for a buyer when the component cost, the selling price, and the demand rate decline at a continuous rate. Two mathematical models are derived and discussed: one model has the suboptimal solution with the fixed replenishment interval and a simpler computational process; the other one has the optimal solution with the varying replenishment interval and a more complicated computational process. The second model results in more profit. Numerical examples are provided to illustrate the two replenishment models. Sensitivity analysis is carried out to investigate the relationship between the parameters and the net profit.     

A method for discrete stochastic MADM problems based on the ideal and nadir solutions

Many real life decision making problems can be modeled as discrete stochastic multi-attribute decision making (MADM) problems. A novel method for discrete stochastic MADM problems is developed based on the ideal and nadir solutions as in the classical TOPSIS method. In a stochastic MADM problem, the evaluations of the alternatives with respect to the different attributes are represented by discrete stochastic variables. According to stochastic dominance rules, the probability distributions of the ideal and nadir variates, both are discrete stochastic variables, are defined and determined for a set of discrete stochastic variables. A metric is proposed to measure the distance between two discrete stochastic variables. The ideal solution is a vector of ideal variates and the nadir solution is a vector of nadir variates for the multiple attributes. As in the classical TOPSIS method, the relative closeness of an alternative is determined by its distances from the ideal and nadir solutions. The rankings of the alternatives are determined using the relative closeness. Examples are presented to illustrate the effectiveness of the proposed method. Through the examples, several significant advantages of the proposed method over some existing methods are discussed.     

Periodic and solitary wave solutions of the attractive and repulsive nonlinear Schrödinger equation

By means of symbolic computation, the first integral method is presented to obtain novel exact solutions of the nonlinear evolution equation. The obtained results include periodic and solitary wave solutions. The power of this manageable method is confirmed and the availability of symbolic computation is demonstrated.     

The structure factor of dense two-dimensional polymer solutions

According to the generalized Porod law the intramolecular structure factor F(q) of compact objects with surface dimension ds scales as F(q)/N≈1/(R(N)q)^2d−ds in the intermediate range of the wave vector q with d being the dimension of the embedding space, N the mass of the objects and R(N)∼N1/d their typical size. By means of molecular-dynamics simulations of a bead-spring model with chain lengths up to N=2048 it is shown that dense self-avoiding polymers in strictly two dimensions (d=2) adopt compact configurations of surface dimension ds=5/4. In agreement with the generalized Porod law the Kratky representation of F(q) thus reveals a nonmonotonous behavior with q²F(q)∼1/(N1/2q)^3/4. Using a similar data analysis we argue briefly that melts of non-concatenated rings in three dimensions become marginally compact with ds=d=3, i.e. q²F(q)∼N⁰/q, for asymptotically long chains.     

A Non-Incremental Finite Element Procedure for the Analysis of Large Deformation of Plates and Shells in Mechanical System Applications

In this investigation, a non-incremental solution procedure for the finite rotationand large deformation analysis of plates is presented. The method, whichis based on the absolute nodal coordinate formulation, leads to plateelements capable of representing exact rigid body motion. In thismethod, continuity conditions on all the displacement gradients areimposed. Therefore, non-smoothness of the plate mid-surface at the nodalpoints is avoided. Unlike other existing finite element formulationsthat lead to a highly nonlinear inertial forces for three-dimensionalelements, the proposed formulation leads to a constant mass matrix, andas a result, the centrifugal and Coriolis inertia forces are identicallyequal to zero. Furthermore, the method relaxes some of the assumptionsused in the classical and Mindlin plate models and automatically satisfiesthe objectivity requirements. By using a generalcontinuum mechanics approach, a relatively simple expression for theelastic forces is obtained. Generalization of the formulation to thecase of shell elements is discussed. As examples of the implementationof the proposed method, two different plate elements are presented; oneplate element does not guarantee the continuity of the displacementgradients between the nodal points, while the other plate elementguarantees this continuity. Numerical results are presented in order todemonstrate the use of the proposed method in the large rotation anddeformation analysis of plates and shells. The numerical results, whichare compared with the results obtained using existing incrementalprocedures, show that the solution obtained using the proposed methodsatisfies the principle of work and energy. These results are obtainedusing explicit numerical integration method. Potential applications ofthe proposed method include high-speed metal forming, vehiclecrashworthiness, rotor blades, and tires.     

Variable-coefficient auxiliary equation method for exact solutions of non-linear evolution equations

In this paper, a variable-coefficient auxiliary equation method is proposed to seek more general exact solutions of non-linear evolution equations. Being concise and straightforward, this method is applied to the Kawahara equation, Sawada–Kotera equation and (2+1)-dimensional Korteweg–de Vries equations. As a result, many new and more general exact solutions are obtained including Jacobi elliptic, hyperbolic and trigonometric function solutions. It is shown that the proposed method provides a straightforward and effective method for non-linear evolution equations in mathematical physics.     

An efficient procedure for finding best compromise solutions to the multi-objective assignment problem

In this paper, we consider the problem of determining a best compromise solution for the multi-objective assignment problem. Such a solution minimizes a scalarizing function, such as the weighted Tchebychev norm or reference point achievement functions. To solve this problem, we resort to a ranking (or k-best) algorithm which enumerates feasible solutions according to an appropriate weighted sum until a condition, ensuring that an optimal solution has been found, is met. The ranking algorithm is based on a branch and bound scheme. We study how to implement efficiently this procedure by considering different algorithmic variants within the procedure: choice of the weighted sum, branching and bounding schemes. We present an experimental analysis that enables us to point out the best variants, and we provide experimental results showing the remarkable efficiency of the procedure, even for large size instances.     

一种OSA/Parlay鉴权接口的安全性研究

本文讨论了基于TSM架构的OSA/Parlay框架,分析了TSM的OSA/Parlay框架中的鉴权安全性,结合现有的两种常用TSM安全分析模型的优点,提出了新的TSM正规模型,并用CoProVe对其进行追踪分析,发现了TSM协议安全上的不足,最后,提出了相应的解决方法。     

The Jacobi elliptic function method and its application for two component BKP hierarchy equations

The periodic wave solutions for the two component BKP hierarchy are obtained by using of Jacobi elliptic function method, in the limit cases, the multiple soliton solutions are also obtained. The properties of some periodic and soliton solution for this system are shown by some figures.     

Asymptotic behavior of positive solutions of sublinear differential equations of Emden-Fowler type

This paper is concerned with asymptotic analysis of positive solutions of the second-order nonlinear differential equation

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