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  • Open Access

    ARTICLE

    A Dynamical Approach to the Spatio-temporal Features of the Portevin-Le Chatelier Effect

    G.Ananthakrishna1

    CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.3, pp. 233-240, 2005, DOI:10.3970/cmes.2005.007.233

    Abstract We show that the extended Ananthakrishna's model exhibits all the features of the Portevin - Le Chatelier effect including the three types of bands. The model reproduces the recently observed crossover from a low dimensional chaotic state at low and medium strain rates to a high dimensional power law state of stress drops at high strain rates. The dynamics of crossover is elucidated through a study of the Lyapunov spectrum. More >

  • Open Access

    ARTICLE

    Systolic Modeling of the Left Ventricle as a Mechatronic System: Determination of Myocardial Fiber's Sarcomere Contractile Characteristics and New Performance Indices

    Dhanjoo N. Ghista1,2, Liang Zhong2, Leok P.Chua2, Eddie Y-K Ng2, Soo T.Lim3, Ru S. Tan3, TerranceS-J Chua3

    Molecular & Cellular Biomechanics, Vol.2, No.4, pp. 217-234, 2005, DOI:10.3970/mcb.2005.002.217

    Abstract Background: In this paper, the left ventricle (LV) is modeled as a cylinder with myocardial fibers located helically within its wall. A fiber is modeled into myocardial structural units (MSUs); the core entity of each MSU is the sarcomeric contractile element. The relationship between the sarcomere unit's contractile force and shortening velocity is expressed in terms of the LV model's wall stress and deformation, and hence in terms of the monitored LV pressure and volume. Then, the LV systolic performance is investigated in terms of a mechatronic (excitation-contraction) model of the sarcomere unit located within the… More >

  • Open Access

    ARTICLE

    Advances in Computational Methods for Multibody System Dynamics

    R.L. Huston1, C.-Q. Liu2

    CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 143-152, 2005, DOI:10.3970/cmes.2005.010.143

    Abstract This paper presents a summary of recent developments in computational methods for multibody dynamics analyses. The developments are presented within the context of an automated numerical analysis. The intent of the paper is to provide a basis for the easy development of computational algorithms. The principal concepts discussed are: differentiation algorithms, partial velocities and partial angular velocities, generalized speeds, Euler parameters, Kane's equations, orthogonal complement arrays, lower body arrays and accuracy testing functions. More >

  • Open Access

    ARTICLE

    Thermal Communication between Two Vertical Systems of Free and Forced Convection via Heat Conduction across a Separating Wall

    M. Mosaad2, A. Ben-Nakhi2, M. H. Al-Hajeri2

    FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.4, pp. 301-314, 2005, DOI:10.3970/fdmp.2005.001.301

    Abstract This work deals with the problem of thermal interaction between two fluid media at two different bulk temperatures and separated by a vertical plate. The problem is analyzed by taking into account the heat conduction across the separating plate. The flow configuration considered is one in which the two vertical boundary layers of free and forced convection developed on plate sides are in parallel flow. The dimensionless parameters governing the thermal interaction mechanisms are analytically deduced. The obtained results are presented in graphs to demonstrate the heat transfer characteristics of investigated phenomenon. The work reports More >

  • Open Access

    ARTICLE

    Numerical Analysis of Parameters in a Laminated Beam Model by Radial Basis Functions

    Y. C. Hon1, L. Ling2, K. M. Liew3

    CMC-Computers, Materials & Continua, Vol.2, No.1, pp. 39-50, 2005, DOI:10.3970/cmc.2005.002.039

    Abstract In this paper we investigate a thermal driven Micro-Electrical-Mechanical system which was originally designed for inkjet printer to precisely deliver small ink droplets onto paper. In the model, a tiny free-ended beam of metal bends and projects ink onto paper. The model is solved by using the recently developed radial basis functions method. We establish the accuracy of the proposed approach by comparing the numerical results with reported experimental data. Numerical simulations indicate that a light (low composite mass) beam is more stable as it does not oscillate much. A soft (low rigidity) beam results More >

  • Open Access

    ARTICLE

    Karyotype description of Pomacea patula catemacensis (Caenogastropoda, Ampullariidae), with an assessment of the taxonomic status of Pomacea patula

    MARÍA ESTHER DIUPOTEX-CHONG1, NÉSTOR J. CAZZANIGA2, ALEJANDRA HERNÁNDEZ-SANTOYO3, JOSÉ MIGUEL BETANCOURT-RULE4

    BIOCELL, Vol.28, No.3, pp. 279-285, 2004, DOI:10.32604/biocell.2004.28.279

    Abstract Mitotic chromosomes of the freshwater snail Pomacea patula catemacensis (Baker 1922) were analyzed on gill tissue of specimens from the type locality (Lake Catemaco, Mexico). The diploid number of chromosomes is 2n = 26, including nine metacentric and four submetacentric pairs; therefore, the fundamental number is FN = 52. No sex chromosomes could be identified. The same chromosome number and morphology were already reported for P. flagellata, i.e., the other species of the genus living in Mexico. The basic haploid number for family Ampullariidae was reported to be n° =°14 in the literature; so, its reduction to More >

  • Open Access

    ARTICLE

    System Optimization for the Development of Ultrasensitive Electronic Biosensors Using Carbon Nanotube Nanoelectrode Arrays

    Jessica E. Koehne, Jun Li1, Alan M. Cassell, Hua Chen, Qi Ye, Jie Han, M. Meyyappan

    Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 69-80, 2004, DOI:10.3970/mcb.2004.001.069

    Abstract Vertically aligned multi-walled carbon nanotubes (MWCNTs) have been reported in fabricating nanoelectrode arrays. Further studies on optimizing this system for the development of ultrasensitive DNA sensors are reported here. The mechanical stability of the as-grown MWCNT array can be improved by polymer coating or SiO2 encapsulation. The latter method provides excellent electronic and ionic insulation to the sidewall of MWCNTs and the underlying metal layer, which is investigated with electrochemical impedance spectroscopy. The insulation ensures well-defined nanoelectrode behavior. A method is developed for selectively functionalizing biomolecules at the open end of MWCNTs while keeping the SiO2 More >

  • Open Access

    ARTICLE

    Flaw tolerant bulk and surface nanostructures of biological systems

    Huajian Gao1,1, Baohua Ji1,1, Markus J. Buehler1,1, Haimin Yao1,1

    Molecular & Cellular Biomechanics, Vol.1, No.1, pp. 37-52, 2004, DOI:10.3970/mcb.2004.001.037

    Abstract Bone-like biological materials have achieved superior mechanical properties through hierarchical composite structures of mineral and protein. Gecko and many insects have evolved hierarchical surface structures to achieve extraordinary adhesion capabilities. We show that the nanometer scale plays a key role in allowing these biological systems to achieve their superior properties. We suggest that the principle of flaw tolerance may have had an overarching influence on the evolution of the bulk nanostructure of bone-like materials and the surface nanostructure of gecko-like animal species. We demonstrate that the nanoscale sizes allow the mineral nanoparticles in bone to More >

  • Open Access

    ARTICLE

    Atomic-level Stress Calculation and Continuum-Molecular System Equivalence

    Shengping Shen1, S. N. Atluri1

    CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 91-104, 2004, DOI:10.3970/cmes.2004.006.091

    Abstract An atomistic level stress tensor is defined with physical clarity, based on the SPH method. This stress tensor rigorously satisfies the conservation of linear momentum, and is appropriate for both homogeneous and inhomogeneous deformations. The formulation is easier to implement than other stress tensors that have been widely used in atomistic analysis, and is validated by numerical examples. The present formulation is very robust and accurate, and will play an important role in the multiscale simulation, and in molecular dynamics. An equivalent continuum is also defined for the molecular dynamics system, based on the developed More >

  • Open Access

    ARTICLE

    Micropropagation of Ilex dumosa (Aquifoliaceae) from nodal segments in a tissue culture system

    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 >

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