Browsing by Author "Phuong, Nguyen Duc"

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Citation Count: Phuong, Nguyen Duc;...et.al. (2022). "Fractional evolution equation with Cauchy data in spaces", Boundary Value Problems, No.100, pp.1-22.
Fractional evolution equation with Cauchy data in spaces
(2022) Phuong, Nguyen Duc; Baleanu, Dumitru; Agarwal, Ravi P.; Long, Le Dinh; 56389
In this paper, we consider the Cauchy problem for fractional evolution equations with the Caputo derivative. This problem is not well posed in the sense of Hadamard. There have been many results on this problem when data is noisy in L2 and Hs . However, there have not been any papers dealing with this problem with observed data in Lp with p = 2. We study three cases of source functions: homogeneous case, inhomogeneous case, and nonlinear case. For all of them, we use a truncation method to give an approximate solution to the problem. Under different assumptions on the smoothness of the exact solution, we get error estimates between the regularized solution and the exact solution in Lp. To our knowledge, Lp evaluations for the inverse problem are very limited. This work generalizes some recent results on this problem
Citation Count: Phuong, Nguyen Duc...et al. (2020). "Fractional order continuity of a time semi-linear fractional diffusion-wave system", Alexandria Engineering Journal, Vol. 59, No. 6, pp. 4959-4968.
Fractional order continuity of a time semi-linear fractional diffusion-wave system
(2020) Phuong, Nguyen Duc; Hoan, Luu Vu Cam; Karapınar, Erdal; Singh, Jagdev; Binh, Ho Duy; Can, Nguyen Huu; 19184
In this work, we consider the time-fractional diffusion equations depend on fractional orders. In more detail, we study on the initial value problems for the time semi-linear fractional diffusion-wave system and discussion about continuity with respect to the fractional derivative order. We find the answer to the question: When the fractional orders get closer, are the corresponding solutions close? To answer this question, we present some depth theories on PDEs and fractional calculus. In addition, we add an example numerical to verify the proposed theory. © 2020
Citation Count: Triet, Nguyen Anh...et al. (2021). "Recovering the initial value for a system of nonlocal diffusion equations with random noise on the measurements", Mathematical Methods in the Applied Sciences, Vol. 44, No. 6, pp. 5188-5209.
Recovering the initial value for a system of nonlocal diffusion equations with random noise on the measurements
(2021) Triet, Nguyen Anh; Binh, Tran Thanh; Phuong, Nguyen Duc; Baleanu, Dumitru; Can, Nguyen Huu; 56389
In this work, we study the final value problem for a system of parabolic diffusion equations. In which, the final value functions are derived from a random model. This problem is severely ill-posed in the sense of Hadamard. By nonparametric estimation and truncation methods, we offer a new regularized solution. We also investigate an estimate of the error and a convergence rate between a mild solution and its regularized solutions. Finally, some numerical experiments are constructed to confirm the efficiency of the proposed method.
Citation Count: Phuong, Nguyen Duc;...et.al. (2022). "Regularization of the Inverse Problem for Time Fractional Pseudo-parabolic Equation with Non-local in Time Conditions", Acta Mathematica Sinica, English Series, Vol.38, No.12, pp.2199-2219.
Regularization of the Inverse Problem for Time Fractional Pseudo-parabolic Equation with Non-local in Time Conditions
(2022) Phuong, Nguyen Duc; Long, Le Dinh; Nguyen, Anh Tuan; Baleanu, Dumitru; 56389
This paper is devoted to identifying an unknown source for a time-fractional diffusion equation in a general bounded domain. First, we prove the problem is non-well posed and the stability of the source function. Second, by using the Modified Fractional Landweber method, we present regularization solutions and show the convergence rate between regularization solutions and sought solution are given under a priori and a posteriori choice rules of the regularization parameter, respectively. Finally, we present an illustrative numerical example to test the results of our theory.
Citation Count: Nguyen Duc Phuong; Nguyen Huy Tuan...et al. (2019). "Regularized solution for nonlinear elliptic equations with random discrete data", Mathematical Methods in the Applied Sciences, Vol. 42, No. 18, pp. 6829-6848.
Regularized solution for nonlinear elliptic equations with random discrete data
(Wiley, 2019) Phuong, Nguyen Duc; Tuan, Nguyen Huy; Baleanu, Dumitru; Luc, Nguyen Hoang; 56389
The aim of this paper is to study the Cauchy problem of determining a solution of nonlinear elliptic equations with random discrete data. A study showing that this problem is severely ill posed in the sense of Hadamard, ie, the solution does not depend continuously on the initial data. It is therefore necessary to regularize the in-stable solution of the problem. First, we use the trigonometric of nonparametric regression associated with the truncation method in order to offer the regularized solution. Then, under some presumption on the true solution, we give errors estimates and convergence rate in L-2-norm. A numerical example is also constructed to illustrate the main results.
Citation Count: Phuong, Nguyen Duc;...et.al. (2023). "Terminal Value Problem For Stochastic Fractional Equation Within An Operator With Exponential Kernel", Fractals, Vol.31, No.4.
Terminal Value Problem For Stochastic Fractional Equation Within An Operator With Exponential Kernel
(2023) Phuong, Nguyen Duc; Hoan, Luu Vu Cam; Baleanu, Dumitru; Nguyen, Anh Tuan; 56389
In this paper, we investigate a terminal value problem for stochastic fractional diffusion equations with Caputo-Fabrizio derivative. The stochastic noise we consider here is the white noise taken value in the Hilbert space W. The main contribution is to investigate the well-posedness and ill-posedness of such problem in two distinct cases of the smoothness of the Hilbert scale space Wν (see Assumption 3.1), which is a subspace of W. When Wν is smooth enough, i.e. the parameter ν is sufficiently large, our problem is well-posed and it has a unique solution in the space of Hölder continuous functions. In contract, in the different case when ν is smaller, our problem is ill-posed; therefore, we construct a regularization result.