George A. Gravvanis¹, Christos K. Filelis-Papadopoulos¹, Paschalis I.Matskanidis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.4, pp. 323-345, 2014, DOI:10.3970/cmes.2014.100.323

Abstract Since the introduction of the Algebraic MultiGrid algorithm (AMG) over twenty years ago, significant progress has been made in improving the coarsening and the convergence behavior of the method. In this paper, an AMG method is introduced that utilizes a new generic approximate inverse algorithm as a smoother in conjunction with common coarsening techniques, such as classical Ruge-Stüben coarsening, CLJP and PMIS coarsening. The proposed approximate inverse scheme, namely Generic Approximate Banded Inverse (GenAbI), is a banded approximate inverse based on Incomplete LU factorization with zero fill–in (ILU(0)). The new class of Generic Approximate Banded… More >

Yidong Bao^1,2, Dongmei Wu^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.4, pp. 277-294, 2014, DOI:10.3970/cmes.2014.100.277

Abstract Aiming at the shortcomings of mass-spring model, this paper, on the basis of preliminary studies, established a new viscoelastic soft tissue model based on meshless structure. The model is consisted of a large quantity of filled spheres, with every three spheres being connected by a spring and a Kelvin structure, which can further enhance the real-time virtual simulation operability while ensure the viscoelasticity of basic model. The stress relaxation and creep equation of the model can be derived from formula derivation. Through setting different parameters to the filled spheres, this model, with certain universal property, More >

T.A. Elgohary^1,2, L. Dong³, J.L. Junkins^2,4, S.N. Atluri^1,4

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.3, pp. 249-275, 2014, DOI:10.3970/cmes.2014.100.249

Abstract In this study, we consider Initial Value Problems (IVPs) for strongly nonlinear dynamical systems, and study numerical methods to analyze short as well as long-term responses. Dynamical systems characterized by a system of second-order nonlinear ordinary differential equations (ODEs) are recast into a system of nonlinear first order ODEs in mixed variables of positions as well as velocities. For each discrete-time interval Radial Basis Functions (RBFs) are assumed as trial functions for the mixed variables in the time domain. A simple collocation method is developed in the time-domain, with Legendre-Gauss-Lobatto nodes as RBF source points… More >

T.A. Elgohary¹, L. Dong², J.L. Junkins³, S.N. Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.1, pp. 59-84, 2014, DOI:10.3970/cmes.2014.100.059

Abstract In this study, we consider ill-posed time-domain inverse problems for dynamical systems with various boundary conditions and unknown controllers. Dynamical systems characterized by a system of second-order nonlinear ordinary differential equations (ODEs) are recast into a system of nonlinear first order ODEs in mixed variables. Radial Basis Functions (RBFs) are assumed as trial functions for the mixed variables in the time domain. A simple collocation method is developed in the time-domain, with Legendre-Gauss-Lobatto nodes as RBF source points as well as collocation points. The duffing optimal control problem with various prescribed initial and final conditions,… More >

S,erson L. Gonzaga de Oliveira¹, Jéssica Renata Nogueira¹, João Manuel R. S. Tavares²

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.1, pp. 31-57, 2014, DOI:10.3970/cmes.2014.100.031

Abstract Triangulations and tetrahedrizations are important geometrical discretization procedures applied to several areas, such as the reconstruction of surfaces and data visualization. Delaunay and Voronoi tessellations are discretization structures of domains with desirable geometrical properties. In this work, a systematic review of algorithms with linear-time behaviour to generate 2D/3D Delaunay and/or Voronoi tessellations is presented. More >

Yan Shen¹, Hong Zhang^1,2,3, Hui Xu¹, Tong Bai¹, Ping Yu¹

FDMP-Fluid Dynamics & Materials Processing, Vol.10, No.1, pp. 63-81, 2014, DOI:10.3970/fdmp.2014.010.063

Abstract Single-unit and multi-unit models of porous media (metal felts) have been used to investigate thermal fluid-structure interaction phenomena in a liquid sodium system. Micro-scale aspects have been studied via numerical simulations. The permeability of metal felts has been measured experimentally to verify the reliability of the models used. This integrated approach has allowed a proper evaluation of the interdependencies among phenomena on different scales (including relevant information on skeleton deformation and pressure drop as a function of different parameters). Pressure drop generally increases with velocity and heat flux for both laminar and turbulent flows. The 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 More >

M. Chang^1,2,3, Y. C. Chou^1,2, P. T. Lin^1,2, J. L. Gabayno^2,4

CMC-Computers, Materials & Continua, Vol.42, No.2, pp. 125-140, 2014, DOI:10.3970/cmc.2014.042.125

Abstract Automated optical inspection systems installed in production lines help ensure high throughput by speeding up inspection of defects that are otherwise difficult to detect using the naked eye. However, depending on the size and surface properties of the products such as micro-cracks on touchscreen panels glass cover, the detection speed and accuracy are limited by the imaging module and lighting technique. Therefore the current inspection methods are still delegated to a few qualified personnel whose limited capacity has been a huge tradeoff for high volume production. In this study, an automated optical technology for in-line… More >

Chein-Shan Liu¹

CMC-Computers, Materials & Continua, Vol.39, No.2, pp. 153-178, 2014, DOI:10.3970/cmc.2014.039.153

Abstract For the numerical solution of an ill-posed positive linear system we combine the methods from invariant manifold theory and sliding mode control theory, developing an affine nonlinear dynamical system with a positive control force and with the residual vector as being a gain vector. This system is proven asymptotically stable to the zero residual vector by using an argument from the Lyapunov stability theory. We find that the system fast tends to the sliding surface and then moves with a sliding mode, such that the resultant sliding mode control algorithm (SMCA) is robust against large More >

Pereira JR¹, AE Duarte², JB Pitombeira³, MAP da Silva², NE de M Beltrão¹, LM Barros²

Phyton-International Journal of Experimental Botany, Vol.82, pp. 275-279, 2013, DOI:10.32604/phyton.2013.82.275

Abstract An experiment was conducted in dryland conditions of the Brazilian Northeast to determine the number of viable weed seeds (seedbank) in an upland cotton crop, and its distribution in the soil profile, before and after using various herbicide treatments. A randomized block design in a split-plot block scheme with 6 replications was used, where the main plots were constituted by a factorial (13 treatments and 2 sampling soil depths), and the subplots by 2 sampling dates. The seedbank was determined by germination of the recovered weed seeds obtained from different soil depths. The highest number More >