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  • Open Access

    ARTICLE

    Two-Layer Passive/Active Anisotropic FSI Models with Fiber Orientation: MRI-Based Patient-Specific Modeling of Right Ventricular Response to Pulmonary Valve Insertion Surgery

    Dalin Tang*, Chun Yang, Tal Geva‡,§, Pedro J. del Nido

    Molecular & Cellular Biomechanics, Vol.4, No.3, pp. 159-176, 2007, DOI:10.3970/mcb.2007.004.159

    Abstract A single-layer isotropic patient-specific right/left ventricle and patch (RV/LV/Patch) combination model with fluid-structure interactions (FSI) was introduced in our previous papers to evaluate and optimize human pulmonary valve replacement/insertion (PVR) surgical procedure and patch design. In this paper, an active anisotropic model with two-layer structure for ventricle wall and tissue fiber orientation was introduced to improve previous isotropic model for more accurate assessment of RV function and potential application in PVR surgery and patch design. A material-stiffening approach was used to model active heart contraction. The computational models were used to conduct ``virtual (computational)'' surgeries More >

  • Open Access

    ARTICLE

    Structural Analysis of the Right Rear Lug of American Airlines Flight 587*

    I.S. Raju1, E.H. Glaessgen1, B.H. Mason1, T. Krishnamurthy1, C.G. Davila1

    CMES-Computer Modeling in Engineering & Sciences, Vol.22, No.1, pp. 1-30, 2007, DOI:10.3970/cmes.2007.022.001

    Abstract A detailed finite element analysis of the right rear lug of the American Airlines Flight 587 - Airbus A300-600R was performed as part of the National Transportation Safety Board's failure investigation of the accident that occurred on November 12, 2001. The loads experienced by the right rear lug were evaluated using global models of the vertical tail, local models near the right rear lug, and a global-local analysis procedure. The right rear lug was analyzed using two modeling approaches. In the first approach, solid-shell type modeling was used, and in the second approach, layered-shell type… More >

  • Open Access

    ARTICLE

    Weight Function Shape Parameter Optimization in Meshless Methods for Non-uniform Grids

    J. Perko1, B. Šarler2

    CMES-Computer Modeling in Engineering & Sciences, Vol.19, No.1, pp. 55-68, 2007, DOI:10.3970/cmes.2007.019.055

    Abstract This work introduces a procedure for automated determination of weight function free parameters in moving least squares (MLS) based meshless methods for non-uniform grids. The meshless method used in present work is Diffuse Approximate Method (DAM). The DAM is structured in 2D with the one or two parameter Gaussian weigh function, 6 polynomial basis and 9 noded domain of influence. The procedure consists of three main elements. The first is definition of the reference quality function which measures the difference between the MLS approximation on non-uniform and hypothetic uniform node arrangements. The second is the… More >

  • Open Access

    ARTICLE

    Weight Optimization of Skeletal Structures with Multi-Point Simulated Annealing

    L. Lamberti1,2, C. Pappalettere1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.3, pp. 183-222, 2007, DOI:10.3970/cmes.2007.018.183

    Abstract This paper presents a novel optimization algorithm for minimizing weight of skeletal structures. The algorithm--denoted as MPISA (Multi Point Improved Simulated Annealing)--utilizes a multi-level simulated annealing scheme where different candidate designs are compared simultaneously. This is done in purpose to increase computational efficiency and to minimize the number of exact structural analyses.
    MPISA is tested in three complicated design problems of skeletal structures: (i) sizing optimization of a planar bar truss under five independent loading conditions including 200 design variables; (ii) sizing-configuration optimization of a cantilevered bar truss including 81 design variables; (iii) sizing-configuration optimization More >

  • Open Access

    ARTICLE

    Spectral Element Approach for Inverse Models of 3D Layered Pavement

    Chun-Ying. Wu1, R. Al-Khoury2, C. Kasbergen2, Xue-Yan. Liu2, A. Scarpas2

    CMES-Computer Modeling in Engineering & Sciences, Vol.17, No.3, pp. 163-172, 2007, DOI:10.3970/cmes.2007.017.163

    Abstract 3D spectral element method in the article is presented to predict the pavement layer modules using field measurement of Falling Weight Deflectometer (FWD). To improve the computational efficiency of the layer-condition assessment, one type of spectral element is proposed to develop the dynamic analysis of 3D multi-layered system subjected to an impulsive load. Each layer in structure is simulated as two-noded layer spectral element or one-noded spectral element in frequency domain. In order to identify the parameters of layered structures, a nonlinear optimization method called Powell hybrid algorithm is employed. The optimization procedure is performed More >

  • Open Access

    ARTICLE

    Prediction of Springback in Straight Flanging using Finite Element Method

    S. K. Panthi1,2, N. Ramakrishnan2, K. K. Pathak2, J. S. Chouhan3

    CMC-Computers, Materials & Continua, Vol.6, No.1, pp. 13-20, 2007, DOI:10.3970/cmc.2007.006.013

    Abstract One of the important features of flanging process is elastic recovery during unloading leading to springback. The elastic recovery is associated with various tool and material parameters. It is difficult to analytically predict the elastic recovery accurately owing to the complex material deformation behavior. In this investigation, a commercially available Finite Element software is used for elasto-plastic analysis of flanging process. The springback is studied varying geometrical, material and friction parameters. The results of the simulation are validated with a few published experimental results. More >

  • Open Access

    ARTICLE

    How to Achieve Kronecker Delta Condition in Moving Least Squares Approximation along the Essential Boundary

    Jin Yeon Cho1

    CMC-Computers, Materials & Continua, Vol.5, No.2, pp. 99-116, 2007, DOI:10.3970/cmc.2007.005.099

    Abstract A novel way is proposed to fulfill Kronecker delta condition in moving least squares (MLS) approximation along the essential boundary. In the proposed scheme, the original MLS weight is modified to boundary interpolatable (BI) weight based on the observation that the support of weight function is exactly the same as the support of MLS nodal shape function. The BI weight is zero along the boundary edges except the edges containing the nodal point associated with the concerned weight. In order to construct the BI weight from the original weight, concept of edge distance function is… More >

  • Open Access

    ARTICLE

    Influence of a high carbohydrate diet on the functional activity of 5-HT1B/1D receptors on human peripheral blood lymphocytes during intense military training

    Mounir Chennaoui, Catherine Drogou, Charles-Yannick Guezennec, Danielle Gomez-Merino

    European Cytokine Network, Vol.17, No.1, pp. 67-74, 2006

    Abstract The present study was undertaken to examine the effect of a high carbohydrate diet on the functional activity of 5-HT1B/1D receptors in human peripheral blood lymphocytes, and on serum cortisol and plasma cytokine responses during intense military training. Thirty two male soldiers (mean age: 21 ± 2 years) were randomly assigned to two groups and received either 3200 kcal/24 h [13440 kJ; habitual diet group (HD)] or 4200 kcal/24 h [17640 kJ, high carbohydrate diet group (HCD)] by adding 1000 kcal (4200 kJ) of fruit jelly to the HD. They took part in a three-week training… More >

  • Open Access

    ARTICLE

    Association of the IL6-174(G/C) polymorphism with C-reactive protein concentration after weight loss in obese men

    Carita Eklund1, Arja Nenonen2,3,4, Katriina Kukkonen-Harjula3, Patrik Borg3, Mikael Fogelholm3,5, Seppo Laine6, Heini Huhtala7, Terho Lehtimäki4, Mikko Hurme1,8

    European Cytokine Network, Vol.17, No.2, pp. 131-135, 2006

    Abstract Elevated plasma concentration of C-reactive protein has emerged as an important predictor of future cardiovascular diseases and metabolic abnormalities in apparently healthy individuals. Obese individuals tend to have elevated C-reactive protein concentrations. Weight loss induces a change in this protein, and single nucleotide polymorphisms in regulating genes might affect this change, since C-reactive protein concentration is known to be approximately 40-50% heritable. Our aim was to study the association between the IL6 -174(G/C), IL1B +3954(C/T) and CRP +1059(G/C) single nucleotide polymorphisms, and CRP concentrations in obese men during a weight reduction program. We genotyped 72… More >

  • Open Access

    ARTICLE

    Genetic polymorphisms for vascular endothelial growth factor in perinatal complications

    Ilona Bányász1, Géza Bokodi1, Barna Vásárhelyi2, András Treszl1, László Derzbach1, András Szabó1, Tivadar Tulassay1,2,3, Ádám Vannay3

    European Cytokine Network, Vol.17, No.4, pp. 266-270, 2006, DOI:10.1684/ecn.2006.0041

    Abstract Low birth weight (LBW) infants have increased susceptibility to perinatal complications. An immature and impaired vascular system may possibly participate in these complications. There is evidence that supports the notion that vascular endothelial growth factor (VEGF), which is an essential regulator of embryonic angiogenesis, plays a central role in the pathogenesis of perinatal complications. We aimed to test whether functional genetic polymorphisms of VEGF are associated with the risk of preterm birth or perinatal morbidity. We enrolled 128 LBW infants (≤ 1500 grams). VEGF T-460C, VEGF C-2578A and VEGF G+405C polymorphisms were determined by real-time… More >

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