Surkay D. Akbarov^1,2,3, Mugan S. Guliev⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.39, No.2, pp. 155-178, 2009, DOI:10.3970/cmes.2009.039.155

Abstract The axisymmetric longitudinal wave propagation in a finite pre-strained compound (composite) cylinder is investigated within the scope of a piecewise homogeneous body model utilizing three-dimensional linearized theory wave propagation in an initially stressed body. The materials of the inner and outer cylinder are assumed to be compressible. The elasticity relations for those are given through the harmonic potential. The algorithm for constructing of the computer programmes and obtaining numerical results is discussed. The numerical results regarding the influences of the initial strains in the inner and outer cylinders on the wave dispersion are presented and More >

M.A.Arafin¹, J.A.Szpunar²

CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 125-140, 2009, DOI:10.3970/cmc.2009.014.125

Abstract A novel microstructure, texture and grain boundary character based model has been proposed to simulate the intergranular crack propagation behavior in textured polycrystalline materials. The model utilizes the Voronoi algorithm and Monte Carlo simulations to construct the microstructure with desired grain shape factor, takes the texture description of the materials to assign the orientations of the grains, evaluates the grain boundary character based on the misorientation angle - axis calculated from the orientations of the neighboring grains, and takes into account the inclination of grain boundaries with respect to the external stress direction. Markov Chain More >

Hsien-Chie Cheng¹, Yu-Chen Hsu², Wen-Hwa Chen²

CMC-Computers, Materials & Continua, Vol.11, No.2, pp. 127-146, 2009, DOI:10.3970/cmc.2009.011.127

Abstract Due to the limitation of fabrication technologies nowadays, structural or atomistic defects are often perceived in carbon nanotubes (CNTs) during the manufacturing process. The main goal of the study aims at providing a systematic investigation of the effects of atomistic defects on the nanomechanical properties and fracture behaviors of single-walled CNTs (SWCNTs) using molecular dynamics (MD) simulation. Furthermore, the correlation between local stress distribution and fracture evolution is studied. Key parameters and factors under investigation include the number, type (namely the vacancy and Stone-Wales defects), location and distribution of defects. Results show that the nanomechanical More >

Torroba MC, HA Paccapelo, L Aguilera, J Mazzola

Phyton-International Journal of Experimental Botany, Vol.77, pp. 93-102, 2008, DOI:10.32604/phyton.2008.77.093

Abstract An optimized methodology for improving regeneration of maize plants by direct organogenesis was evaluated. Our objective was to embarobtain genetically homogeneous plants through in vitro methods to regenerate clumps of multiple shoots from shoot tips at high frequency. Cultures were initiated from shoot tips of experimental lines of maize on a Murashige & Skoog (MS) medium supplemented with 2 mg/l benziladenine. Two experimental forage maize lines were used, in which two frequencies of subcultures were evaluated, namely line L. 850 (every 15 or 30 days) and line L.769 (every 30 days). It was observed that the More >

Giménez¹ C, E de García², O Haddad³

Phyton-International Journal of Experimental Botany, Vol.77, pp. 65-79, 2008, DOI:10.32604/phyton.2008.77.065

Abstract Evaluation of clonal micropropagation and phenotype stability of elite somaclones are critical steps for development of new varieties. In the present work somaclon variant CIEN BTA-03 (resistant to Black Sigatoka), obtained through in vitro process from cultivar Williams (susceptible to Black Sigatoka), was micropropagated via apical shoot culture for five multiplication cycles in 0.5 mg/l of benzyl-aminopurine (BA). To verify the genetic stability of the progeny of this elite material, random amplified polymorphic DNA (RAPD) markers were used. A total of 5,292 monomorphic bands were obtained from the amplification of fifty six DNA samples (extracted from More >

A. Brasiliano¹, W.R. Souza², G.N. Doz³, J.L.V. Brito⁴

Structural Durability & Health Monitoring, Vol.4, No.2, pp. 53-66, 2008, DOI:10.3970/sdhm.2008.004.053

Abstract It can be observed that usually, during structures useful life they are submitted to deterioration processes that, depending on the intensity, may affect their performance and load capacity and, as a result, their safety. In this case, it is necessary to accomplish an inspection in order to evaluate the conditions of the structure and to locate and quantify the intensity of the damage. Another important point is to study the behavior of brittle material beams with cracks, as an attempt of understanding the rupture mechanism and crack propagation phenomenon. In this paper, the Residual Error More >

D. I. Fotiadis¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.2, pp. 85-92, 2008, DOI:10.3970/icces.2008.005.085

Abstract Quantitative ultrasound has attracted significant interest in the evaluation of bone fracture healing. Animal and clinical studies have demonstrated that the propagation velocity across fractured bones can be used as an indicator of healing. Researchers have recently employed computational methods for modeling wave propagation in bones aiming to gain insight into the underlying mechanisms of wave propagation and to further enhance the monitoring capabilities of ultrasound. In this paper we review the computational studies of ultrasound wave propagation in intact and healing bones. More >

R. Martin¹, D. Komatitsch^1,2, S. D. Gedney³

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.3, pp. 274-304, 2008, DOI:10.3970/cmes.2008.037.274

Abstract In the context of the numerical simulation of seismic wave propagation, the perfectly matched layer (PML) absorbing boundary condition has proven to be efficient to absorb surface waves as well as body waves with non grazing incidence. But unfortunately the classical discrete PML generates spurious modes traveling and growing along the absorbing layers in the case of waves impinging the boundary at grazing incidence. This is significant in the case of thin mesh slices, or in the case of sources located close to the absorbing boundaries or receivers located at large offset. In previous work… More >

Jianping Wei¹, Xianyue Su^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.1, pp. 65-84, 2008, DOI:10.3970/cmes.2008.037.065

Abstract The steady-state response of the wave propagation in a magneto-electro-elastic square column (MEESC) was studied. Some new characteristics were discovered: the guided waves are classified in the forms of the Quasi-P, Quasi-SV and Quasi-SH waves and ordered by the standing wave number, and the three type guided waves are corresponding to the extension, twist and shear modes of the body vibration; the induced electric and magnetic fields can be aroused by the propagating stress wave. We proposed a self-adjoint method, by which the guided-wave restriction condition was derived. After finding the corresponding orthogonal sets, the More >

Shueei-Muh Lin^1,3, Sen-Yung Lee², Cheng-Chuan Tsai², Chien-Wi Chen²,Wen-Rong Wang³, Jenn-Fa Lee³

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.1, pp. 33-54, 2008, DOI:10.3970/cmes.2008.034.033

Abstract The conventional theories for circulation of arteries are emphasized on fluid behavior or some simplified models for experimental utility. In this study, a new mathematical theory is proposed to describe the wave propagation through the elastic tube filled with viscous and incompressible fluid. The radial, longitudinal and flexural vibrations of a tube wall are introduced simultaneously. Meanwhile, the linearlized momentum and continuity equations of tube flow field are expressed in the integral form. Based on these considerations, three wave modes are obtained simultaneously. These wave modes are the flexural, Young and Lamb modes, respectively. The… More >