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  • Open Access

    ARTICLE

    On the Multigrid Method Based on Finite Difference Approximate Inverses

    Christos K. Filelis-Papadopoulos1, George A. Gravvanis1

    CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.3, pp. 233-253, 2013, DOI:10.3970/cmes.2013.090.232

    Abstract During the last decades, multigrid methods have been extensively used in order to solve large scale linear systems derived from the discretization of partial differential equations using the finite difference method. Approximate Inverses in conjunction with Richardon’s iterative method could be used as smoothers in the multigrid method. Thus, a new class of smoothers based on approximate inverses could be derived. Effectiveness of explicit approximate inverses relies in the fact that they are close approximants to the inverse of the coefficient matrix and are fast to compute in parallel. Furthermore, the class of finite difference More >

  • Open Access

    ARTICLE

    Human umbilical artery smooth muscle exhibits a 2-apb- sensitive capacitative contractile response evoked by vasoactive substances and exprsses mrnas for stim, orai and trpc channelsa

    ANA ROCÍO ROLDÁN PALOMO1, PEDRO MARTÍN1, ALEJANDRO REBOLLEDO1*, NICOLÁS ENRIQUE1, LUIS E. FLORES2, VERÓNICA MILESI1

    BIOCELL, Vol.36, No.2, pp. 73-81, 2012, DOI:10.32604/biocell.2012.36.073

    Abstract After depletion of intracellular Ca2+ stores the capacitative response triggers an extracellular Ca2+ influx through store-operated channels (SOCs) which refills these stores. Our objective was to explore if human umbilical artery smooth muscle presented this response and if it was involved in the mechanism of serotonin- and histamine-induced contractions. Intracellular Ca2+ depletion by a Ca2+-free extracellular solution followed by Ca2+ readdition produced a contraction in artery rings which was inhibited by the blocker of Orai and TRPC channels 2-aminoethoxydiphenyl borate (2-APB), suggesting a capacitative response. In presence of 2-APB the magnitude of a second paired contraction by serotonin… More >

  • Open Access

    ARTICLE

    Dynamic Lung Modeling and Tumor Tracking Using Deformable Image Registration and Geometric Smoothing

    Yongjie Zhang, Yiming Jing, Xinghua Liang, Guoliang Xu, Lei Dong

    Molecular & Cellular Biomechanics, Vol.9, No.3, pp. 213-226, 2012, DOI:10.3970/mcb.2012.009.213

    Abstract A greyscale-based fully automatic deformable image registration algorithm, based on an optical flow method together with geometric smoothing, is developed for dynamic lung modeling and tumor tracking. In our computational processing pipeline, the input data is a set of 4D CT images with 10 phases. The triangle mesh of the lung model is directly extracted from the more stable exhale phase (Phase 5). In addition, we represent the lung surface model in 3D volumetric format by applying a signed distance function and then generate tetrahedral meshes. Our registration algorithm works for both triangle and tetrahedral… More >

  • Open Access

    ARTICLE

    Elasto-Damage Modeling of Biopolymer Molecules Response

    F. Maceri1, M. Marino1, G. Vairo1

    CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.5, pp. 461-482, 2012, DOI:10.3970/cmes.2012.087.461

    Abstract The mechanical behavior of biopolymer mo -le -cu -les is herein addressed and a novel predictive model for their elasto-damage response is proposed. Both entropic and energetic elastic mechanisms are accounted for, and coupled by consistent equilibrium conditions. Moreover, through non-smooth mechanics arguments, molecular damage is modeled accounting for failure due to both mechanical and non-mechanical damage sources. The model is applied to collagen molecules and an excellent agreement with available experimental tests and atomistic computations is shown. The proposed predictive theory can be usefully integrated in hierarchical models of biological structures towards a multiscale More >

  • Open Access

    ARTICLE

    On the Modeling of Surface Tension and its Applications by the Generalized Interpolation Material Point Method

    L. Chen1 J. H. Lee1, C.-f. Chen1

    CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.3, pp. 199-224, 2012, DOI:10.3970/cmes.2012.086.199

    Abstract This paper presents a numerical procedure to model surface tension using the Generalized Interpolation Material Point (GIMP) method which employs a background mesh in solving the equations of motion. The force due to surface tension is formulated at the mesh grid points by using the continuum surface force (CSF) model and then added to the equations of motion at each grid point. In GIMP, we use the grid mass as the color function in CSF and apply a moving average smoothing scheme to the grid mass to improve the accuracy in calculating the surface interface. More >

  • Open Access

    ARTICLE

    POOL BOILING CHF FOR PENTANE, HEXANE, METHANOL, FC-72, FC-87, AND R113 ON A SMOOTH HORIZONTAL SURFACE

    Cheng-Kang Guan, James F. Klausner*, Renwei Mei

    Frontiers in Heat and Mass Transfer, Vol.2, No.4, pp. 1-6, 2011, DOI:10.5098/hmt.v2.4.3002

    Abstract Pool boiling critical heat flux (CHF) has been measured for pentane, hexane, methanol, FC-72, FC-87, and R113 on a 25.4 mm diameter smooth brass horizontal surface at five different reduced pressures ranging from 0.01to 0.24. The CHF data are compared with various established CHF models as well as the new mechanistic CHF lift-off model recently proposed by the authors. The dependence of CHF on pressure is examined, and it is found that the lift-off model gives a reasonably good prediction of changes in CHF with step changes in the reduced pressure. The R113 and FC-72 More >

  • Open Access

    ARTICLE

    Apigenin inhibits cell migration through MAPK pathways in human bladder smooth muscle cells

    QINGXIN LIU , XIANGGUI CHEN, GUOLIN YANG1 , XUEWEN MIN3 , AND MAOXIAN DENG1,*

    BIOCELL, Vol.35, No.3, pp. 71-80, 2011, DOI:10.32604/biocell.2011.35.071

    Abstract Apigenin, a nonmutagenic flavonoid, has been shown to possess free radical scavenging activities, anticarcinogenic properties, antioxidant and anti-inflammatory effects. Recently, apigenin was reported to cause gastric relaxation in murine. To assess possible effects of apigenin on migration of bladder smooth muscle (SM) cell, we isolated SM cells from peri-cancer tissue of human bladder and established a cell model that was capable to overexpress transiently MEKK1 (MEK kinase 1). Results showed that overexpression of active human MEKK1 by adenoviruses infection induced migration of human bladder smooth muscle (hBSM) cells and phosphorylation of MAPKs, ERK, JNK and More >

  • Open Access

    ARTICLE

    Effect of cold storage, heat, smoke and charcoal on breaking seed dormancy of Arctostaphylos pungens HBK (Ericaceae)

    Jurado E1, M Márquez-Linares2, J Flores3

    Phyton-International Journal of Experimental Botany, Vol.80, pp. 101-105, 2011, DOI:10.32604/phyton.2011.80.101

    Abstract We evaluated the effect of cold storage and fire-related cues on seed germination of Arctostaphylos pungens HBK (Mexican Manzanita), a common shrub in poorly managed pine-oak forests in Durango, Mexico. Because this shrub has a high density in previously burnt forests, we investigated the effect that high temperatures, smoke and charcoal might have on seed germination of this species. Seeds were collected fresh from the shrubs. The highest germination was 30% for seeds that had been cold stored, heat shocked, past through smoke and watered with diluted charcoal. More >

  • Open Access

    ABSTRACT

    Application of the Gradient Smoothing Technique to the Natural Neighbour Galerkin Method for the Couple-Stress Elasticity

    K. Wang, S.J. Zhou, Z.F. Nie

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 115-116, 2011, DOI:10.3970/icces.2011.018.115

    Abstract The natural neighbour Galerkin method is tailored to solve boundary value problems of the couple-stress elasticity to model the size dependent behaviour of materials. This method is based on the displacement-based Galerkin approach, and the calculation of the global stiffness matrix is performed using gradient smoothing technique combined with the non-Sibsonian partition of unity approximation scheme. This method possesses the following properties: the complex C1-continuous approximation scheme is avoided without using either Lagrange multipliers or penalty parameters; no domain integrals involved in the assembly of the global stiffness matrix; and the imposition of essential boundary More >

  • Open Access

    ABSTRACT

    A three dimensional efficient Galerkin mshfree formulation for large deformation analysis of soil slope failure

    Dongdong Wang, Zhuoya Li, Youcai Wu

    The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 107-108, 2011, DOI:10.3970/icces.2011.017.107

    Abstract Meshfree methods have experienced substantially fundamental development and various applications. One distinguished advantage for meshfree methods is that they can relieve the mesh tangling burden of FEM and are more suitable for finite deformation analysis. In this work a three dimensional updated Lagrangian Galerkin meshfree formulation with improved computational efficiency is presented to analyze the failure of soil slopes. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is obtained as… More >

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