Chein-Shan Liu^1,2

CMC-Computers, Materials & Continua, Vol.5, No.2, pp. 151-160, 2007, DOI:10.3970/cmc.2007.005.151

Abstract An accurate magnetization requires that both the reversible and irreversible components be modeled. The classical Landau-Lifshitz model deals with only the irreversible component of magnetization. We first subject the Landau-Lifshitz equation to an AC external field by performing a computation through the closed-form solution and the resulting hysteresis loop is displayed to show its deficiency. Then we modify the Landau-Lifshitz model into a new one by including a reversible part and an irreversible part accompanying with the switching criteria between these two states. With the new solutions we display the influence of parameters on the hysteresis loops of magnetic materials… More >

L. Godinho A. ¹, A. Tadeu¹, P. Amado Mendes¹

CMC-Computers, Materials & Continua, Vol.5, No.2, pp. 117-128, 2007, DOI:10.3970/cmc.2007.005.117

Abstract This paper presents a strategy for using the Method of Fundamental Solutions (MFS) to model the propagation of elastic waves around thin structures, like empty cracks or thin rigid screens, located in a homogeneous elastic medium. The authors make use of a simple approach for modeling these propagation conditions using the MFS together with decomposition of the domain into distinct regions. This approach makes it possible to avoid the undetermined system of equations that arises from imposing boundary conditions at both sides of a thin structure. The numerical implementation of the MFS is performed in the frequency domain, making use… More >

Jian Xu^1,2,*, Zhihao Jiang¹, Andi Wang¹, Chen Wang¹, Fucai Zhou¹

CMC-Computers, Materials & Continua, Vol.57, No.3, pp. 589-602, 2018, DOI:10.32604/cmc.2018.03820

Abstract With the development of cloud storage, the problem of efficiently checking and proving data integrity needs more consideration. Therefore, much of growing interest has been pursed in the context of the integrity verification of cloud storage. Provable data possession (PDP) and Proofs of retrievablity (POR) are two kinds of important scheme which can guarantee the data integrity in the cloud storage environments. The main difference between them is that POR schemes store a redundant encoding of the client data on the server so as to she has the ability of retrievablity while PDP does not have. Unfortunately, most of POR… More >

Daofu Gong^1,2, Yan Chen^1,2, Haoyu Lu^1,*, Zhenyu Li³, Yibing Han¹

CMC-Computers, Materials & Continua, Vol.57, No.2, pp. 243-260, 2018, DOI:10.32604/cmc.2018.03781

Abstract To detect and recover random tampering areas, a combined-decision-based self-embedding watermarking scheme is proposed herein. In this scheme, the image is first partitioned into 2×2 size blocks. Next, the high 5 bits of a block’s average value is embedded into its offset block. The tampering type of block is detected by comparing the watermarks of its pre-offset and post-offset blocks. The theoretical analysis and experiments demonstrate that the proposed scheme not only has a lower ratio of false detection but also better performance with regard to avoiding random tampering. More >

Yanbin Wang^1,2, Deli Gao¹, Jun Fang¹

CMC-Computers, Materials & Continua, Vol.48, No.1, pp. 25-42, 2015, DOI:10.3970/cmc.2015.048.025

Abstract In this paper, the buckling and collapse analysis of offshore pipeline under combined tension, bending moment, and external pressure has been presented with theoretical analysis and FE (finite element) simulation method respectively. Based on the model initially proposed by Kyriakides, a 2-D theoretical model has been further developed. To verify the correctness and accuracy of the model proposed in this paper, numerical simulations have been conducted with 3-D FE model using ABAQUS software. Good consistency has been shown between the calculation results which validate the availability of the theoretical analysis. On this basis, the influence of load path, material properties,… More >

P.G. Santos¹, J. Carbajo², L. Godinho³, J. Ramis²

CMC-Computers, Materials & Continua, Vol.43, No.2, pp. 109-136, 2014, DOI:10.3970/cmc.2014.043.109

Abstract The study of periodic structures, namely sonic crystals, for sound attenuation purposes has been a topic of intense research in the last years. Some efficient methods are available in literature to solve the problem of sound propagation in the presence of this kind of structures such as those based in the Multiple Scattering Theory (MST) or the Finite Element Method (FEM). In this paper a solution based on the Method of Fundamental Solutions (MFS) which presents advantages, namely in computational discretization and calculation costs, is presented. The proposed formulation considers the presence of elastic ring shaped scatterers, correctly accounting for… More >

Shiv Narayan¹, R M Jha¹

CMC-Computers, Materials & Continua, Vol.37, No.2, pp. 97-108, 2013, DOI:10.3970/cmc.2013.037.097

Abstract A novel metamaterial based FSS (frequency selective surfaces) structure is presented in this paper for wideband airborne radome applications. The proposed metamaterial-FSS structure consists of three layers, where a DPS (double positive sign) layer is sandwiched between a MNG (μ-negative) and ENG (ε- negative) layer, exhibits very good bandpass characteristics inside the operational band along with excellent roll-off characteristics outside the band. The EM performance analysis of the proposed structure has been carried out using transmission line transfer matrix (TLTM) method, which shows excellent bandpass characteristics over a wide frequency range. The transmission efficiency is over 95% both at normal… More >

Liviu Marin¹

CMC-Computers, Materials & Continua, Vol.17, No.3, pp. 233-274, 2010, DOI:10.3970/cmc.2010.017.233

Abstract We investigate two algorithms involving the relaxation of either the given boundary temperatures (Dirichlet data) or the prescribed normal heat fluxes (Neumann data) on the over-specified boundary in the case of the iterative algorithm of Kozlov91 applied to Cauchy problems for two-dimensional steady-state anisotropic heat conduction (the Laplace-Beltrami equation). The two mixed, well-posed and direct problems corresponding to every iteration of the numerical procedure are solved using the method of fundamental solutions (MFS), in conjunction with the Tikhonov regularization method. For each direct problem considered, the optimal value of the regularization parameter is chosen according to the generalized cross-validation (GCV)… More >

LiviuMarin ¹

CMC-Computers, Materials & Continua, Vol.12, No.1, pp. 71-100, 2009, DOI:10.3970/cmc.2009.012.071

Abstract In this paper, the alternating iterative algorithm originally proposed by Kozlov, Maz'ya and Fomin (1991) is numerically implemented for the Cauchy problem in anisotropic heat conduction using a meshless method. Every iteration of the numerical procedure consists of two mixed, well-posed and direct problems which are solved using the method of fundamental solutions (MFS), in conjunction with the Tikhonov regularization method. For each direct problem considered, the optimal value of the regularization parameter is chosen according to the generalized cross-validation (GCV) criterion. An efficient regularizing stopping criterion which ceases the iterative procedure at the point where the accumulation of noise… More >

Liviu Marin¹, Andreas Karageorghis²

CMC-Computers, Materials & Continua, Vol.10, No.3, pp. 259-294, 2009, DOI:10.3970/cmc.2009.010.259

Abstract We study the stable numerical identification of an unknown portion of the boundary on which a given boundary condition is provided and additional Cauchy data are given on the remaining known portion of the boundary of a two-dimensional domain for problems governed by either the Helmholtz or the modified Helmholtz equation. This inverse geometric problem is solved using the method of fundamental solutions (MFS) in conjunction with the Tikhonov regularization method. The optimal value for the regularization parameter is chosen according to Hansen's L-curve criterion. The stability, convergence, accuracy and efficiency of the proposed method are investigated by considering several… More >