基于收敛方差跟踪的水下目标运动分析

水下目标的被动跟踪由于隐蔽性好, 有着很强的需求背景。本文提出了基于收敛方差跟踪的水下目标运动分析算法, 由于采用方位频率Kalman滤波, 可以得到速度渐近无偏估计, 利用速度估计值对目标位置初值进行线性估计, 进而估计目标运动状态, 采用该方法可以有效消除直接应用伪线性Kalman滤波算法引起的初值偏差, 仿真结果表明, 该方法对目标运动要素具有良好的估计性能。

X-滤波和ε-滤波LMS算法性能分析

研究了 X-滤波和ε-滤波 L MS算法的性能 ,给出了它们的均值收敛和方差收敛条件 ,提出了 X-滤波和ε-滤波L MS算法具有二次稳定性的充分条件 .仿真结果表明 ,这两种 L MS算法对被控对象的估计误差具有不敏感的特性 .

Adaptive genetic algorithm with the criterion of premature convergence

To counter the defect of traditional genetic algorithms, an improved adaptivegenetic algorithm with the criterion of premature convergence is provided. The occurrence ofpremature convergence is forecasted using colony entropy and colony variance. When prematureconvergence occurs, new individuals are generated in proper scale randomly based on superiorindividuals in the colony. We use these new individuals to replace some individuals in the oldcolony. The updated individuals account for 30 percent - 40 percent of all individuals and the sizeof scale is related to the distribution of the extreme value of the target function. Simulationtests show that there is much improvement in the speed of convergence and the probability of globalconvergence.

Convergence on Finite Difference Solution for Semilinear Wave Equation in One Space Variable

In this paper,the convergence and stability of the ’Leap-frog’ finite difference scheme for the semilinear wave equation are proved by using of the bounded extensive method under more generalized condition for the nonlinear term. The more complex standard a priori estimates are avoided so that the theoretical results are complemented for the scheme which was presented by Perring and Skyrne (1962).

Second-order difference scheme for a nonlinear model of wood drying process

A numerical simulation for a model of wood drying process is considered. The model is given by a couple of nonlinear differential equations. One is a nonlinear parabolic equation and the other one is a nonlinear ordinary equation. A difference scheme is derived by the method of reduction of order. First, a new variable is introduced and the original problem is rewritten into a system of the first-order differential equations. Secondly, a difference scheme is constructed for the later problem. The solvability, stability and convergence of the difference scheme are proved by the energy method. The convergence order of the difference scheme is secondorder both in time and in space. A prior error estimate is put forward. The new variable is put aside to reduce the computational cost. A numerical example testifies the theoretical result.

A second-order convergent and linearized difference schemefor the initial-boundary value problemof the Korteweg-de Vries equation

To numerically solve the initial-boundary value problem of the Korteweg-de Vries equation,an equivalent coupled system of nonlinear equations is obtained by the method of reduction of order.Then,a difference scheme is constructed for the system.The new variable introduced can be separated from the difference scheme to obtain another difference scheme containing only the original variable.The energy method is applied to the theoretical analysis of the difference scheme.Results show that the difference scheme is uniquely solvable and satisfies the energy conservation law corresponding to the original problem.Moreover,the difference scheme converges when the step ratio satisfies a constraint condition,and the temporal and spatial convergence orders are both two.Numerical examples verify the convergence order and the invariant of the difference scheme.Furthermore,the step ratio constraint is unnecessary for the convergence of the difference scheme.Compared with a known two-level nonlinear difference scheme,the proposed difference scheme has more advantages in numerical calculation.

Moving collocation methods for time fractional differential equations and simulation of blowup

A moving collocation method is proposed and implemented to solve time fractional differential equations. The method is derived by writing the fractional differential equation into a form of time difference equation. The method is stable and has a third-order convergence in space and first-order convergence in time for either linear or nonlinear equations. In addition, the method is used to simulate the blowup in the nonlinear equations.

GLOBAL SUPERCONVERGENCE ANALYSIS OF WILSON ELEMENT FOR SOBOLEV AND VISCOELASTICITY TYPE EQUATIONS

In this paper the Wilson nonconforming finite element is employed to solve Sobolev and viscoelasticity type equations. By means of post-processing technique, global superconvergence estimates are obtained for quasi-uniform rectangular meshes. Finally, an error correction scheme is presented.

ESTIMATION ON SEMIVARYING COEFFICIENT MODELS WITH DIFFERENT DEGREES OF SMOOTHNESS

Semivarying coefficient models are frequently used in statistical models.In this paper,under the condition that the coefficient functions possess different degrees of smoothness,a two-stepmethod is proposed.In the case,one-step method for the smoother coefficient functions cannot beoptimal.This drawback can be repaired by using the two-step estimation procedure.The asymptoticmean-squared error for the two-step procedure is obtained and is shown to achieve the optimal rate ofconvergence.A few simulation studies are conducted to evaluate the proposed estimation methods.

Some recent advances on vertex centered finite volume element methods for elliptic equations

In this paper, we report our recent advances on vertex centered finite volume element methods （FVEMs） for second order partial differential equations （PDEs）. We begin with a brief review on linear and quadratic finite volume schemes. Then we present our recent advances on finite volume schemes of arbitrary order. For each scheme, we first explain its construction and then perform its error analysis under both HI and L2 norms along with study of superconvergence properties.

NONCONFORMING FINITE ELEMENT METHOD FOR NONLINEAR PARABOLIC EQUATIONS

A nonconforming finite element method for the nonlinear parabolic equations is studied inthis paper.The convergence analysis is presented and the optimal error estimate in L^2(‖·‖_h)norm isobtained through Ritz projection technique,where ‖·‖_h is a norm over the finite element space.

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.