排序方式: 共有238条查询结果,搜索用时 31 毫秒
51.
Mehdi Dehghan Mehrdad Lakestani 《Numerical Methods for Partial Differential Equations》2007,23(6):1277-1289
Problems for parabolic partial differential equations with nonlocal boundary conditions have been studied in many articles, but boundary value problems for hyperbolic partial differential equations have so far remained nearly uninvestigated. In this article a numerical technique is presented for the solution of a nonclassical problem for the one‐dimensional wave equation. This method uses the cubic B‐spline scaling functions. Some numerical results are reported to support our study. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
52.
53.
In this article, we introduce two new asynchronous multisplitting methods for solving the system of weakly nonlinear equations
Ax = G(x) in which A is an n × n real matrix and G(x) = (g
1(x), g
2(x), . . . , g
n
(x))
T
is a P-bounded mapping. First, by generalized accelerated overrelaxation (GAOR) technique, we introduce the asynchronous parallel
multisplitting GAOR method (including the synchronous parallel multisplitting AOR method as a special case) for solving the
system of weakly nonlinear equations. Second, asynchronous parallel multisplitting method based on symmetric successive overrelaxation
(SSOR) multisplitting is introduced, which is called asynchronous parallel multisplitting SSOR method. Then under suitable
conditions, we establish the convergence of the two introduced methods. The given results contain synchronous multisplitting
iterations as a special case. 相似文献
54.
Akbar Mohebbi Mehdi Dehghan 《Numerical Methods for Partial Differential Equations》2008,24(5):1222-1235
In this article, we introduce a high‐order accurate method for solving one‐space dimensional linear hyperbolic equation. We apply a compact finite difference approximation of fourth order for discretizing spatial derivative of linear hyperbolic equation and collocation method for the time component. The main property of this method additional to its high‐order accuracy due to the fourth order discretization of spatial derivative, is its unconditionally stability. In this technique the solution is approximated by a polynomial at each grid point that its coefficients are determined by solving a linear system of equations. Numerical results show that the compact finite difference approximation of fourth order and collocation method produce a very efficient method for solving the one‐space‐dimensional linear hyperbolic equation. We compare the numerical results of this paper with numerical results of (Mohanty, 3 .© 2008 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 2008 相似文献
55.
Parabolic partial differential equations with overspecified data play a crucial role in applied mathematics and engineering, as they appear in various engineering models. In this work, the radial basis functions method is used for finding an unknown parameter p(t) in the inverse linear parabolic partial differential equation ut = uxx + p(t)u + φ, in [0,1] × (0,T], where u is unknown while the initial condition and boundary conditions are given. Also an additional condition ∫01k(x)u(x,t)dx = E(t), 0 ≤ t ≤ T, for known functions E(t), k(x), is given as the integral overspecification over the spatial domain. The main approach is using the radial basis functions method. In this technique the exact solution is found without any mesh generation on the domain of the problem. We also discuss on the case that the overspecified condition is in the form ∫0s(t) u(x,t)dx = E(t), 0 < t ≤ T, 0 < s(t) < 1, where s and E are known functions. Some illustrative examples are presented to show efficiency of the proposed method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
56.
Mehdi Tatari Mehdi Dehghan Mohsen Razzaghi 《Numerical Methods for Partial Differential Equations》2008,24(3):911-923
We present a numerical method for the solution of heat equation with sufficiently smooth initial condition, using fundamental solutions of heat equation in terms of singularities. In this work various aspects of this method such as efficiency, stability, and convergency are given and a comparison with some well‐known finite difference methods will be obtained. Numerical results are reported to support the superiority of the developed method. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008 相似文献
57.
Mehdi Dehghan Jalil Manafian Heris Abbas Saadatmandi 《Mathematical Methods in the Applied Sciences》2010,33(11):1384-1398
In this work, the homotopy perturbation method (HPM), the variational iteration method (VIM) and the Adomian decomposition method (ADM) are applied to solve the Fitzhugh–Nagumo equation. Numerical solutions obtained by these methods when compared with the exact solutions reveal that the obtained solutions produce high accurate results. The results show that the HPM, the VIM and the ADM are of high accuracy and are efficient for solving the Fitzhugh–Nagumo equation. Also the results demonstrate that the introduced methods are powerful tools for solving the nonlinear partial differential equations. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
58.
The investigation of flower scent represents an important field of modern biological research which is directed towards special theories of biological recognition. The headspace solid phase microextraction coupled with gas chromatography-mass spectrometry was used to identify the volatile components of Carum copticum (C. copticum) cultivated in Iran. The compounds were identified according to their retention indices and mass spectra (EI, 70 eV). The effects of different parameters, such as the desorption time, the extraction temperature, the sample mass, the addition of salt, the pre-equilibration time and the extraction time, on the extraction efficiency were investigated. The optimized conditions were: the desorption time, 2 min; the extraction temperature, 58 degrees Celsius; the sample mass, 1.000 g in 4.0 mL 2.0 M NaCl solution; the pre-equilibration time, 25 min; the extraction time, 20 min. Finally, ten components were identified in the volatile components of C. copticum. The major components of C. copticum were thymol (68.2%), gamma-terpinene (13.9%), p-cymene (11.6%), myrcene (1.0%) and beta-pinene (0.6%). Precision of the proposed method is good and %RSD less than 14 was obtained. 相似文献
59.
In this work we will consider He's variational iteration method for solving second-order initial value problems. We will discuss the use of this approach for solving several important partial differential equations. This method is based on the use of Lagrange multipliers for identification of optimal value of a parameter in a functional. This procedure is a powerful tool for solving the large amount of problems. Using the variational iteration method, it is possible to find the exact solution or an approximate solution of the problem. This technique provides a sequence of functions which converges to the exact solution of the problem. Our emphasis will be on the convergence of the variational iteration method. In the current paper this scheme will be investigated in details and efficiency of the approach will be shown by applying the procedure on several interesting and important models. 相似文献
60.
Our aim in this paper is to investigate the global asymptotic stability of all positive solutions of the higher order nonlinear difference equationwhere B, C and α, β, γ are positive, k {1, 2, 3, … }, and the initial conditions x−2k+1, … , x−1, x0 are positive real numbers. We show that the unique positive equilibrium of the equation is globally asymptotically stable and has some basins that depend on certain conditions posed on the coefficients. Our concentration is on invariant intervals, the character of semicycles, and the boundedness of the above mentioned equation. Our final comments are about informative examples. 相似文献