Yuan Chen¹, Liangtao Duan¹, Weize Sun^{2, *}, Jingxin Xu³

CMC-Computers, Materials & Continua, Vol.62, No.2, pp. 849-859, 2020, DOI:10.32604/cmc.2020.07115

Abstract In this paper, we address the frequency estimator for 2-dimensional (2-D) complex sinusoids in the presence of white Gaussian noise. With the use of the sinc function model of the discrete Fourier transform (DFT) coefficients on the input data, a fast and accurate frequency estimator is devised, where only the DFT coefficient with the highest magnitude and its four neighbors are required. Variance analysis is also included to investigate the accuracy of the proposed algorithm. Simulation results are conducted to demonstrate the superiority of the developed scheme, in terms of the estimation performance and computational complexity. More >

Gang Xu^{1, *}, Ran Ling¹, Lishan Deng¹, Qing Wu¹, Weiyin Ma²

CMC-Computers, Materials & Continua, Vol.62, No.1, pp. 309-319, 2020, DOI:10.32604/cmc.2020.06509

Abstract In this paper, we propose a novel image interpolation method by using Gaussian-Sinc automatic interpolators with partition of unity property. A comprehensive comparison is made with classical image interpolation methods, such as the bicubic interpolation, Lanczos interpolation, cubic Schaum interpolation, cubic B-spline interpolation and cubic Moms interpolation. The experimental results show the effectiveness of the improved image interpolation method via some image quality metrics such as PSNR and SSIM. More >

Mohd. Ahmed^1,*, Mohamed Hechmi El Ouni¹, Devinder Singh², Nabil Ben Kahla¹

CMES-Computer Modeling in Engineering & Sciences, Vol.121, No.2, pp. 687-786, 2019, DOI:10.32604/cmes.2019.06886

Abstract The paper presents a parametric study on interpolation techniques based postprocessed error estimation in finite element elastic analysis by varying important parameters of recovery, interpolation scheme and type of patch construction. The quality of error estimation with recovery parameters is compared in terms of local and global effectivity of error estimation, rate of error convergence, and adaptively refined meshes. A mesh free moving least square interpolation technique with proven reliability and effectivity is introduced for improving the recovery of finite element solution errors. The post-processed finite element solutions of elastic problems are presented for performance study under different parameters of… More >

J. Sladek¹, V. Sladek, Ch.Zhang²

Structural Durability & Health Monitoring, Vol.1, No.2, pp. 131-144, 2005, DOI:10.3970/sdhm.2005.001.131

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed for crack analysis in two-dimensional (2-d), anisotropic and linear elastic solids with continuously varying material properties. Both quasi-static and transient elastodynamic problems are considered. For time-dependent problems, the Laplace-transform technique is utilized. A unit step function is used as the test function in the local weak-form. It is leading to local boundary integral equations (LBIEs) involving only a domain-integral in the case of transient dynamic problems. The analyzed domain is divided into small subdomains with a circular shape. The moving least-squares (MLS) method is adopted for approximating the physical… More >

S. G. Bardenhagen^1,2, E. M. Kober³

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.6, pp. 477-496, 2004, DOI:10.3970/cmes.2004.005.477

Abstract The Material Point Method (MPM) discrete solution procedure for computational solid mechanics is generalized using a variational form and a Petrov–Galerkin discretization scheme, resulting in a family of methods named the Generalized Interpolation Material Point(GIMP) methods. The generalizationpermits identification with aspects of other point or node based discrete solution techniques which do not use a body–fixed grid, i.e. the “meshless methods”. Similarities are noted and some practical advantages relative to some of these methods are identified. Examples are used to demonstrate and explain numerical artifact noise which can be expected inMPM calculations. Thisnoiseresultsin non-physical local variations at the material points,… More >

G. C. Bourantas¹, E. D. Skouras^2,3, V. C. Loukopoulos⁴, G. C. Nikiforidis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 187-212, 2010, DOI:10.3970/cmes.2010.064.187

Abstract Meshfree point collocation method (MPCM) is developed, solving the velocity-vorticity formulation of Navier-Stokes equations, for two-dimensional, steady state incompressible viscous flow problems in the presence of heat transfer. Particular emphasis is placed on the application of the velocity-correction method, ensuring the continuity equation. The Gaussian Radial Basis Functions (GRBF) interpolation is employed to construct the shape functions in conjunction with the framework of the point collocation method. The cases of forced, natural and mixed convection in a 2D rectangular enclosure are examined. The accuracy and the stability of the proposed scheme are demonstrated through three representative, well known and established… More >

Yongzheng Ma, Hong Zheng

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 7-8, 2011, DOI:10.3970/icces.2011.019.007

Abstract The traditional Discontinuous Deformation Analysis (DDA) method, like other Discrete Element Methods, is created to model the discrete block system. The extended DDA method based on meshless interpolations means utilizing meshless interpolations, usually the Moving Least-Squares interpolations, to present block displacement field. In the new extensions here, the effects of earthquake, excavation and bolt reinforcement on the assemblages of large blocks are modeled: for modeling earthquake, the initial acceleration value from earthquake at certain DDA time step can be interpolated from the earthquake acceleration vs. time curve; the modeling of excavation is by reversing in-situ stresses at excavation internal boundaries… More >

N. Mai-Duy¹, T. Tran-Cong¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.3, pp. 127-132, 2007, DOI:10.3970/icces.2007.003.127

Abstract This lecture presents an overview of the Integral Collocation formulation for numerically solving partial differential equations (PDEs). However, due to space limitation, the paper only describes the latest development, namely schemes based only on one-dimensional (1D) integrated interpolation even in multi-dimensional problems. The proposed technique is examined with Chebyshev polynomials and radial basis functions (RBFs). The latter can be used in both regular and irregular domains. For both basis functions, the accuracy and convergence rates of the new technique are better than those of the differential formulation. More >

Chein-Shan Liu¹, Yung-Wei Chen², Jiang-Ren Chang²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.2, pp. 93-100, 2007, DOI:10.3970/icces.2007.003.093

Abstract A new collocation method is developed here to solve the elliptic boundary value problems with singularities. Specifically, we consider the Motz problem as a test of the performance of the new method, which is found accurate and effective. More >

V. Sladek¹, J. Sladek¹, M. Tanaka²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 69-84, 2005, DOI:10.3970/cmes.2005.007.069

Abstract An efficient numerical method is proposed for 2-d potential problems in anisotropic media with continuously variable material coefficients. The method is based on the local integral equations (utilizing a fundamental solution) and meshfree approximation of field variable. A lot of numerical experiments are carried out in order to study the numerical stability, accuracy, convergence and efficiency of several approaches utilizing various interpolations. More >