Aleksandr N. Guz¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 217-230, 2005, DOI:10.3970/cmes.2005.008.217

Abstract The ultrasonic non-destructive method of determination of stresses in near-the-surface layers of solid bodies is based on the regularities of elastic surface wave propagation in bodies with initial (residual) stresses. Above mentioned regularities are received in the framework of the 3-D linearized theory of waves propagation in bodies with initial (residual) stresses. Computational methods are used for solution of the dispersion equations as applied to problems under consideration. Description of the non-destructive method and information on instruments and devices for measurements are presented. Some examples of non-destructive determination of stresses in near-the-surface layers of materials More >

C. K. Au¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 1-14, 2005, DOI:10.3970/cmes.2005.008.001

Abstract Solving the Eikonal equation is popular due to its potential applications in various areas. Numerical method is the most common approach to solve the equation. This paper presents a geometric approach to solve the equation. Each point in a two dimensional domain with a given velocity field is characterized by the least time from the source. The path of least time is obtained by the Euler equations characterizing the extrema of the variation problem. A geometric representation of the space time function for the source is constructed. The solution to the eikonal equation is obtained More >

George F. Carrier¹, Harry Yeh²

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 113-122, 2005, DOI:10.3970/cmes.2005.010.113

Abstract Sea-bottom displacements associated with seismic events are confined largely to strips of large but finite aspect ratio. We analyze waves that are initiated on such a strip and that propagate across a region of finite depth. We invoke the classical shallow-water-wave theory to obtain rather comprehensive descriptions of the non-dispersive aspects of the waves. The directivity of the energy radiation and the domain of pulse persistence are discussed. More >

J. Bielak¹, O. Ghattas², E.-J. Kim³

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 99-112, 2005, DOI:10.3970/cmes.2005.010.099

Abstract We present a parallel octree-based finite element method for large-scale earthquake ground motion simulation in realistic basins. The octree representation combines the low memory per node and good cache performance of finite difference methods with the spatial adaptivity to local seismic wavelengths characteristic of unstructured finite element methods. Several tests are provided to verify the numerical performance of the method against Green's function solutions for homogeneous and piecewise homogeneous media, both with and without anelastic attenuation. A comparison is also provided against a finite difference code and an unstructured tetrahedral finite element code for a More >

R. MEDINA, M. FALOCI, M.A. MARASSI, AND L.A. MROGINSKI.

BIOCELL, Vol.28, No.1, pp. 13-20, 2004, DOI:10.32604/biocell.2004.28.013

Abstract An efficient clonal propagation procedure for six rice varieties cultivated in Argentina was developed by using shoot tip cultures, and the genetic stability of the micropropagated plants was verified by isozyme analysis. One week old seedlings obtained on MS medium were sectioned and subcultured on MS medium (0.75% agar) supplemented with different combination and concentrations of cytokinins (BAP and KIN) and auxins (2,4-D and NAA). After four weeks of culture, multiple shoots were obtained. The best response was observed on MS supplemented with BAP 5 mg l^-1. Shoot clumps were multiplied in MS liquid medium containing More >

E. Ferretti ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 453-476, 2004, DOI:10.3970/cmes.2004.006.453

Abstract The Cell Method (CM) code with automatic remeshing for crack propagation analysis [Ferretti (2003)] is here used for modeling the pullout test. Particular emphasis is given to the analysis in the Mohr-Coulomb plane, since previous numerical models were not decisive in describing failure mechanism in pullout tests. The interpretations of experimental and analytical studies vary widely, and none of the existing explanations offer a complete description of the progressive failure of the concrete medium [Yener (1994)]. Nor do most existing interpretations appear to be totally compatible with the experimental evidence. Analysis of the failure mechanism… More >

T. Furumura¹, L. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.2, pp. 153-168, 2004, DOI:10.3970/cmes.2004.006.153

Abstract Recent developments of the Earth Simulator, a high-performance parallel computer, has made it possible to realize realistic 3D simulations of seismic wave propagations on a regional scale including higher frequencies. Paralleling this development, the deployment of dense networks of strong ground motion instruments in Japan (K-NET and KiK-net) has now made it possible to directly visualize regional seismic wave propagation during large earthquakes. Our group has developed an efficient parallel finite difference method (FDM) code for modeling the seismic wavefield and a 3D visualization technique, both suitable for implementation on the Earth Simulator. Large-scale 3D… More >

S. Tchouikov¹, T. Nishioka¹, T. Fujimoto¹

CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 191-204, 2004, DOI:10.3970/cmc.2004.001.191

Abstract Phenomena of dynamic crack branching are investigated numerically from a macroscopic point of view. Repetitive branching phenomena, interaction of cracks after bifurcation and their stability, bifurcation into two and three branches were the objectives of this research. For the analysis of dynamic crack branching, recently we developed moving finite element method based on Delaunay automatic triangulation [Nishioka, Furutuka, Tchouikov and Fujimoto (2002)]. In this study this method was extended to be applicable for complicated crack branching phenomena, such as bifurcation of the propagating crack into more than two branches, multiple crack bifurcation and so on. More >

L. G. Zhou¹, L. M. Hsiung², Hanchen Huang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.3, pp. 245-252, 2004, DOI:10.3970/cmes.2004.006.245

Abstract Using molecular dynamics simulations, we study the deformation of polysynthetically twinned (PST) TiAl at room temperature. The simulation cell is pre-strained and thermodynamically relaxed to zero stress, so that no dislocations pre-exist in γ−α₂ interfaces. A uniaxial compression is then applied along one 1/6<112] direction. Our results show that interfacial dislocation pairs nucleate at the γ−α₂ interface under the compression. The glide and agglomeration of these dislocations lead to the nucleation of deformation twins from the interface. Based on our studies, twins may nucleate without pre-existing interfacial dislocations. Further we have monitored the propagation of the More >

C. Luna, P. Sansberro*, L. Mroginski, J. Tarragó

BIOCELL, Vol.27, No.2, pp. 205-212, 2003, DOI:10.32604/biocell.2003.27.205

Abstract Micropropagation of Ilex dumosa var. dumosa R. (“yerba señorita”) from nodal segments containing one axillary bud was investigated. Shoot regeneration from explants of six-year-old plants was readily achieved in ¹/₄ strength Murashige and Skoog medium (¹/₄ MS) plus 30 gr·L^-1 sucrose and supplemented with 4.4 µM BA. Further multiplication and elongation of the regenerated shoots were obtained by subculture in a fresh medium of similar composition with 1.5 gr·L^-1 sucrose. Rooting induction from shoots were achieved in two steps: 1) 7 days in ¹/₄ MS (30 gr·L^-1 sucrose, 0.25 % Phytagel^®) with 7.3 µM IBA and 2) 21 days in More >