Oscillation in a Variable Delay Logistic Difference Equation

Consider the nonautonomous delay logistic equation △yn=pnyn（1-yn-ln/k）,n≥0, where {Pn}n≥0 is a sequence of nonnegative real numbers, {In}n≥0 is a sequence of positive integers satisfying n→∞lim（n-ln）=∞, and k is a positive constant. Only solutions which are positive for n ≥ 0 are considered. We obtain a new sufficient for all positive solutions of （1） to oscillate about k which contains the corresponding result in [2] when i = 1.

Nonlinear delay difference equations for housing dynamics assuming heterogeneous backward-looking expectations

China＇s first interest rate hike during the last decade, aiming to cool down the seemingly overheated real estate market, had aroused more caution on housing market. This paper aims to analyze the housing price dynamics after an unanticipated economic shock, which was believed to have similar properties with the backward-looking expecta- tion models. The analysis of the housing price dynamics is based on the cobweb model with a simple user cost affected demand and a stock-flow supply assumption. Several nth- order delay rational difference equations are set up to illustrate the properties of housing dynamics phenomena, such as the equilibrium or oscillations, overshoot or undershoot and convergent or divergent, for a kind of heterogeneous backward-looking expectation models. The results show that demand elasticity is less than supply elasticity is not a necessary condition for the occurrence of oscillation. The housing price dynamics will vary substantially with the heterogeneous backward-looking expectation assumption and some other endogenous factors.

CONVERGENCE OF SOLUTIONS FOR A CLASS OF DIFFERENCE EQUATIONS WITH VARIABLE DELAY

In this paper, we study the convergence of solutions for a class of difference equations with variable delay and give some results about the solutions of the equations converge to a constant. Our results generalize the conclusions obtained in .

Convergence of Linear Multistep Methods and One-Leg Methods for Index-2 Differential-Algebraic Equations with a Variable Delay

Linear multistep methods and one-leg methods are applied to a class of index-2 nonlinear differential-algebraic equations with a variable delay.The corresponding convergence results are obtained and successfully confirmed by some numerical examples.The results obtained in this work extend the corresponding ones in literature.

Stability and convergence of the variable directions difference scheme for one nonlinear two-dimensional model

The system of two-dimensional nonlinear partial differential equations is considered. This system describes the vein formation in meristematic tissues of young leaves. Variable directions difference scheme is constructed and investigated. Absolute stability regarding space and time steps of scheme is shown. The convergence statement for the constructed scheme is proved. Rate of convergence is given. Various numerical experiments are carried out and results of some of them are considered in this paper. Comparison of numerical experiments with the results of the theoretical investigation is given too.

Compact Difference Method for Time-Fractional Neutral Delay Nonlinear Fourth-Order Equation

In this paper, we present a compact finite difference method for a class of fourth-order nonlinear neutral delay sub-diffusion equations in two-dimensional space. The fourth-order problem is first transformed into a second-order system by a reduced-order method. Next by using compact operator to approximate the second order space derivatives and L2-1σ formula to approximate the time fractional derivative, the difference scheme which is fourth order in space and second order in time is obtained. Then, the existence and uniqueness of solution, the convergence rate of and the stability of the scheme are proved. Finally, numerical results are given to verify the accuracy and validity of the scheme.

ONE-PARAMETER FINITE DIFFERENCE METHODS AND THEIR ACCELERATED SCHEMES FOR SPACE-FRACTIONAL SINE-GORDON EQUATIONS WITH DISTRIBUTED DELAY

This paper deals with numerical methods for solving one-dimensional(1D)and twodimensional(2D)initial-boundary value problems(IBVPs)of space-fractional sine-Gordon equations(SGEs)with distributed delay.For 1D problems,we construct a kind of oneparameter finite difference(OPFD)method.It is shown that,under a suitable condition,the proposed method is convergent with second order accuracy both in time and space.In implementation,the preconditioned conjugate gradient(PCG)method with the Strang circulant preconditioner is carried out to improve the computational efficiency of the OPFD method.For 2D problems,we develop another kind of OPFD method.For such a method,two classes of accelerated schemes are suggested,one is alternative direction implicit(ADI)scheme and the other is ADI-PCG scheme.In particular,we prove that ADI scheme can arrive at second-order accuracy in time and space.With some numerical experiments,the computational effectiveness and accuracy of the methods are further verified.Moreover,for the suggested methods,a numerical comparison in computational efficiency is presented.

ECONOMICAL DIFFERENCE SCHEME FOR ONE MULTI-DIMENSIONAL NONLINEAR SYSTEM

The multi-dimensional system of nonlinear partial differential equations is considered. In two-dimensional case, this system describes process of vein formation in higher plants. Variable directions finite difference scheme is constructed. The stability and convergence of that scheme are studied. Numerical experiments are carried out. The appropriate graphical illustrations and tables are given.

A STOCHASTIC ALGORITHM FOR FAULT INVERSE PROBLEMS IN ELASTIC HALF SPACE WITH PROOF OF CONVERGENCE

A general stochastic algorithm for solving mixed linear and nonlinear problems was introduced in[11].We show in this paper how it can be used to solve the fault inverse problem,where a planar fault in elastic half-space and a slip on that fault have to be reconstructed from noisy surface displacement measurements.With the parameter giving the plane containing the fault denoted by m and the regularization parameter for the linear part of the inverse problem denoted by C,both modeled as random variables,we derive a formula for the posterior marginal of m.Modeling C as a random variable allows to sweep through a wide range of possible values which was shown to be superior to selecting a fixed value[11].We prove that this posterior marginal of m is convergent as the number of measurement points and the dimension of the space for discretizing slips increase.Simply put,our proof only assumes that the regularized discrete error functional for processing measurements relates to an order 1 quadrature rule and that the union of the finite-dimensional spaces for discretizing slips is dense.Our proof relies on trace class operator theory to show that an adequate sequence of determinants is uniformly bounded.We also explain how our proof can be extended to a whole class of inverse problems,as long as some basic requirements are met.Finally,we show numerical simulations that illustrate the numerical convergence of our algorithm.

OSCILLATION OF SOLUTIONS FOR A CLASS OF UNBOUNDED DELAY DIFFERENTIAL EQUATIONS

In this paper we present infinite-integral conditions for the oscillation of a class of unbounded delay differential equations.

变分数阶扩散方程的新隐式差分法

针对变分数阶扩散方程,提出新隐式差分法.首先,对二阶空间导数和Riemann-Liouville型变时间分数阶导数算子进行离散化处理,将变分数阶扩散方程转化为代数方程组求解;然后,借助Fourier级数技术给出了新隐式差分法的收敛性分析;最后,通过数值算例检验该方法,计算结果表明了新隐式差分法的可行性和有效性.

变系数时间-空间分数阶对流-扩散方程的数值算法比较

文章分别采用显式差分格式、隐式差分格式和Crank-Nicholson格式,数值求解变系数时间-空间分数阶对流-扩散方程,并从局部截断误差、稳定性和计算量3个方面对数值算法进行了比较分析,通过数值算例验证了分析结果。

变系数分数阶反应-扩散方程的数值解法

考虑了变系数分数阶反应-扩散方程,将一阶的时间偏导数和二阶的空间偏导数分别用Caputo分数阶导数和Riemann-Liouville分数阶导数替换,利用L1算法和G算法对方程的变系数分数阶导数进行适当的离散,给出了该方程的一种计算有效的隐式差分格式,并证明了这个差分格式是无条件稳定和无条件收敛的,且具有o(τ+h)收敛阶.最后用数值例子说明差分格式是有效的.

一类变系数微分方程差分格式的收敛性(英文)

本文首先对一类变系数微分方程建立有限差分格式.然后利用矩阵的特征值和范数理论,讨论该格式解的收敛性和唯一性.通过数值算例,说明该格式既有效又便于模拟.并且文中所用方法还能用于高阶微分方程和某些非线性微分方程问题的研究.

一类八阶变系数微分方程的数值方法(英文)

本文首先对一类八阶变系数微分方程建立了有限差分格式,并将该格式表示成矩阵的形式.然后,利用矩阵特征值和范数的理论,证明该格式解的收敛性和唯一性.借助数值算例说明该格式既有效、又便于模拟.另外,文中所用方法还能用于应用中的某些非线性微分方程问题的研究.

一类变系数常微分方程的一个显式差分格式

有限差分法广泛应用于微分方程数值求解中。本文对于一类变系数常微分方程的边值问题建立了一个显式差分格式,它的截断误差阶为O(h2),证明了该格式存在唯一解,且在L∞范数意义下是无条件收敛和稳定的。

非线性变阶空间-时间分数阶对流-扩散方程的全隐式有限差分格式

针对非线性变阶空间-时间分数阶对流-扩散方程的初边值问题,提出一种全隐式有限差分格式.首先,分别对Riemann-Liouville型变时间分数阶导数算子和Riemann-Liouville型变空间分数阶导数算子和广义Riesz分数阶导数算子进行离散化处理;然后,通过离散的能量方法证明全隐式有限差分格式的稳定性和收敛性,并验证其收敛阶为O(τ+h);最后,通过数值算例检验该方法.试验结果表明:全隐式有限差分格式求解非线性变阶空间-时间分数阶对流-扩散方程初边值问题是可行和有效的.

基于多项式预处理的特殊双变量矩阵方程异类约束解算法

针对共轭梯度法求解双变量矩阵方程异类约束解收敛速度较慢的问题,引入多项式预处理技术,构造了一个预处理矩阵,从而改变了系数矩阵奇异值的分布,使奇异值的比值趋于1,达到提高收敛速度的目的。针对特殊一类双变量矩阵方程异类约束解的求解问题,构造了多项式预处理共轭梯度法,证明了该算法是收敛性的,且具有Q-线性收敛速度。数值实验结果表明,本算法比共轭梯度法收敛速度更快,迭代时间更短。

非线性变阶分数阶扩散方程的全隐差分格式

对于变阶的非线性分数阶扩散方程,提出了一种全隐的差分格式。然后,通过离散的能量方法证明了所提出的格式是无条件稳定的,其收敛阶为O(τ+h)。通过数值试验表明,全隐的差分格式是有效的和可靠的。

解双边空间分数阶对流扩散方程的二阶隐式有限差分法

给出一类解变系数双边空间分数阶对流扩散方程的隐式有限差分格式,并证明这类格式当分数阶导数α∈[17(1/2)-1/2,2]时无条件稳定且由此得出收敛阶为O(Δt+h2)。最后给出数值算例验证。