A. Cruz-Estrada^1,2, E. Ruiz-Sánchez², I.L. Medina Baizabal¹, E. Balam-Uc¹ and M. Gamboa-Angulo^1,*

Phyton-International Journal of Experimental Botany, Vol.88, No.2, pp. 161-170, 2019, DOI:10.32604/phyton.2019.05809

Abstract The development of plant-derived products to control Bemisia tabaci Genn. (Hemiptera: Aleyrodidae) is an urgent need for production of horticultural crops. Plant extracts and essential oils of several species of the genus Eugenia (Myrtaceae) have shown insecticidal activity. In southern Mexico, leaf extracts from Eugenia winzerlingii showed nematicidal effect but its insecticidal properties have not been explored. Therefore, the objective of this study was to evaluate the insecticidal effect of aqueous and organic extracts from E. winzerlingii leaves on B. tabaci egg, nymph and adult stages, and else to explore its nursery propagation. Then, extracts of this species were obtained… More >

A. Frangi¹, L. Ghezzi, P. Faure-Ragani²

CMES-Computer Modeling in Engineering & Sciences, Vol.15, No.1, pp. 41-48, 2006, DOI:10.3970/cmes.2006.015.041

Abstract Three dimensional magneto-mechanical problems at low frequency are addressed by means of a coupled fast Boundary Element - Finite Element approach with total scalar potential and focusing especially on the issue of global force calculation on movable ferromagnetic parts. The differentiation of co-energy in this framework and the use of Maxwell tensor are critically discussed and the intrinsic links are put in evidence. Three examples of academic and industrial applications are employed for validation. More >

R. Springhetti¹, G. Novati¹, M. Margonari²

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.1, pp. 67-80, 2006, DOI:10.3970/cmes.2006.013.067

Abstract With reference to potential and elastostatic problems, a BEM-FEM coupling procedure, based on the symmetric Galerkin version of the BEM, is developed; the continuity conditions at the interface of the BE and FE subdomains are enforced in weak form; the global linear system is characterized by a symmetric coefficient matrix. The procedure is numerically tested with reference first to 2D potential problems and successively to 3D elastoplastic problems (with plastic strains confined to the FE subdomain). More >

J.T. Verbis¹, S.V. Tsinopoulos², D. Polyzos²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 803-814, 2002, DOI:10.3970/cmes.2002.003.803

Abstract In the present work the iterative effective medium approximation (IEMA) is appropriately used for wave dispersion and attenuation predictions in fiber-reinforced composites that microscopically exhibit a non-uniform fiber distribution. Two types of composites with such irregular topology of fibers are considered. The first contains a regular distribution of clusters of fibers embedded in a composite matrix with uniformly distributed fibers, and the second a uniform distribution of matrix-rich inclusions embedded in a fiber-rich regular composite medium. The resulting from the application of the IEMA scattering problems are solved numerically by means of a two dimensional boundary element method. The obtained… More >

G.D. Hatzigeorgiou¹, D.E. Beskos¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 791-802, 2002, DOI:10.3970/cmes.2002.003.791

Abstract This paper presents a general boundary element methodology for the dynamic analysis of three-dimensional inelastic solids and structures. Inelasticity is simulated with the aid of the continuum damage theory. The elastostatic fundamental solution is employed in the integral formulation of the problem and this creates in addition to the surface integrals, volume integrals due to inertia and inelasticity. Thus an interior discretization in addition to the usual surface discretization is necessary. Isoparametric linear quadrilateral elements are used for the surface discretization and isoparametric linear hexahedra for the interior discretization. Advanced numerical integration techniques for singular and nearly singular integrals are… More >

Z. D. Han¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.6, pp. 699-716, 2002, DOI:10.3970/cmes.2002.003.699

Abstract As shown in an earlier work, the FEM-BEM alternating method is an efficient and accurate method for fracture analysis. In the present paper, a further improvement is formulated and implemented for the analyses of three-dimensional arbitrary surface cracks by modeling the cracks in a local finite-sized subdomain using the symmetric Galerkin boundary element method (SGBEM). The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and… More >

A. Aimi¹, M. Diligenti¹, S. Panizzi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.2, pp. 185-220, 2010, DOI:10.3970/cmes.2010.058.185

Abstract In this paper we consider 2D wave propagation Neumann exterior problems reformulated in terms of a hypersingular boundary integral equation with retarded potential. Starting from a natural energy identity satisfied by the solution of the differential problem, the related integral equation is set in a suitable space-time weak form. Then, a theoretical analysis of the introduced formulation is proposed, pointing out the novelties with respect to existing literature results. At last, various numerical simulations will be presented and discussed, showing accuracy and stability of the space-time Galerkin boundary element method applied to the energetic weak problem. More >

Jinyou Xiao, Wenjing Ye

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 101-102, 2011, DOI:10.3970/icces.2011.018.101

Abstract Traditional boundary element methods (BEMs) suffer from densely populated system matrices. In recent years, acceleration techniques like the wavelet BEM (WBEM) have been developed which reduce the complexity considerably. In WBEM, one uses appropriate wavelet bases for the discretization, yielding numerically sparse matrices which result in extremely fast matrix-vector multiplications. However, in conventional WBEM the wavelets are constructed by uniform refinement of parametrically described patches. Such approaches have difficulties in dealing with practical problems with complicated geometries because patch-wise surface parameterization is generally not available. To avoid this limitation, Tausch proposed a method in [1] to construct wavelets directly on… More >

H.B. Chen

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.4, pp. 105-106, 2011, DOI:10.3970/icces.2011.020.105

Abstract The calculation of field values and their derivatives near the domain boundary through the boundary element method (BEM) will meet the nearly singularity problem, i.e. the boundary layer effect problem. The tangential derivatives of field values on the boundary often meet an obvious deduction of calculation accuracy. An effective algorithm was proposed by Chen et al. [1,2] to treat these two problems in the same time in elastic BEM and it was recently extended to calculate the second derivative values in potential problem [3]. This algorithm is based on the regularized formulations and is now called the regularized indirect algorithm.… More >

Ju E Yang, Qiya Hu, Dehao Yu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.3, pp. 71-72, 2011, DOI:10.3970/icces.2011.016.071

Abstract In this paper, based on the natural boundary reduction method advanced bu Feng and Yu, we are concerned with a domain decomposition method with nonmatching grids for a certain nonlinear interface problem in unbounded domains. We first discuss a new coupling of finite element and boundary element by adding an auxiliary circle. Then we use a dual basis multipier on the interface to provide the numerical analysis with nonmatching grids. Finally, we give some numerical examples further to confirm our theoretical results. More >