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  • Open Access


    Interval Uncertain Optimization of Vehicle Suspension for Ride Comfort

    C. Jiang1,2, S. Yu1, H.C. Xie1, B.C. Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 443-467, 2014, DOI:10.3970/cmes.2014.098.443

    Abstract Based on the interval analysis method, this paper proposes an uncertain optimization model for the ride comfort in vehicles and achieves the optimal design of vehicle ride comfort under the condition of complicated uncertainty. The spring stiffness and shock absorber damping of suspension is regarded as the design parameters, while the root mean square (RMS) of the vehicle body acceleration is treated as the design objective and the corresponding constraints are composed of suspension stiffness, natural frequency and RMS of suspension dynamic deflection. Moreover, the uncertainties of key parameters, such as sprung mass, tire stiffness, vehicle speed and road roughness,… More >

  • Open Access


    A New Multi-objective Reliability-based Robust Design Optimization Method

    Zichun Yang1,2, Maolin Peng1,3,4, Yueyun Cao1, Lei Zhang1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 409-442, 2014, DOI:10.3970/cmes.2014.098.409

    Abstract A new multi-objective reliability-based robust design optimization (M ORBRDO) model is proposed which integrats the multi-objective robustness, the reliability sensitivity robustness and the six sigma robustness design idea. The pure-quadratic polynomial functions are adopted to fit the performance objective functions (POF) and the ultimate limited state functions (ULSF) of the structure. Based on the ULSF and the checking point method, the equations of the first order reliability index are calculated. The mapping transformation method is employed when the non-normal distribution variables are included. According to the POF and the Taylor series expansion method, the equations of mean value and standard… More >

  • Open Access


    Disclosing the Complexity of Nonlinear Ship Rolling and Duffing Oscillators by a Signum Function

    Chein-Shan Liu1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.4, pp. 375-407, 2014, DOI:10.3970/cmes.2014.098.375

    Abstract In this paper we study the nonlinear dynamical system x·=f(x,t) from a newly developed theory, viewing the time-varying function of sign(||f||2||x||2− 2(f·x)2) = −sign(cos 2θ) as a key factor, where θ is the intersection angle between x and f. It together with sign(cos θ) can reveal the complexity of nonlinear Duffing oscillator and a quadratic ship rolling oscillator. The barcode is formed by plotting sign(||f||2||x||2− 2(f·x)2) with respect to time. We analyze the barcode to point out the bifurcation of subharmonic motions and the range of chaos in the parameter space. The bifurcation diagram obtained by plotting the percentage… More >

  • Open Access


    Hybrid Simulation and Observation of Human Vertebral Endplate Morphology

    É. Budyn1, A. Bilagi2, V. Subramanian3, A.A. Espinoza Orías4, N. Inoue4

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 341-374, 2014, DOI:10.32604/cmes.2014.098.341

    Abstract Focal damage such as cartilaginous defects, erosions, micro-fractures, Schmorl nodes and thinning in the human vertebral endplate are thought to contribute to intervertebral disc degeneration by compromising the nutrition transport between the vertebral bone marrow and the disc nucleus pulposus. However, microfractures in the endplate are currently not detectable by conventional clinical radiographic methods. Nonetheless high quality visualisation of the human endplate is possible by means of advanced light microscopy and appropriate staining. The objective of this study focuses on efficient and inexpensive multi-scale protocols to prepare the surfaces of human endplate specimens for morphometric characterisations at the tissue and… More >

  • Open Access


    Variable Viscosity and Density Biofilm Simulations using an Immersed Boundary Method, Part I: Numerical Scheme and Convergence Results

    Jason F. Hammond1, Elizabeth J. Stewart2, John G. Younger3, Michael J.Solomon2, David M. Bortz4,5

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 295-340, 2014, DOI:10.32604/cmes.2014.098.295

    Abstract The overall goal of this work is to develop a numerical simulation which correctly describes a bacterial biofilm fluid-structure interaction and separation process. In this, the first of a two-part effort, we fully develop a convergent scheme and provide numerical evidence for the method order as well as a full 3D separation simulation. We use an immersed boundary-based method (IBM) to model and simulate a biofilm with density and viscosity values different from than that of the surrounding fluid. The simulation also includes breakable springs connecting the bacteria in the biofilm which allows the inclusion of erosion and detachment into… More >

  • Open Access


    Activation Pattern of Nuclear Factor-kB in Skin after Mechanical Stretch – a Multiscale Modeling Approach

    V.B.Shim 1, K. Mithraratne 1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 279-294, 2014, DOI:10.32604/cmes.2014.098.279

    Abstract The activation of NF-kB is an important precursor in developing melanoma. However the role of mechanical stimulation in the NF-kB activation has not been studied. We used a multiscale computational modeling approach to investigate the role of mechanical stimulation and the skin tissue internal structures in the activation of NF-kB. Our model is made up of three levels – 1) the macro level where a FE model of the Zygomaticus major muscle was developed; 2) the meso level where a micro FE model of the skin block using a sample from human cadaver was developed; 3) the cell level where… More >

  • Open Access


    A Computational Modeling Framework for Heat Transfer Processes in Laser-Induced Dermal Tissue Removal

    T.I. Zohdi1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 261-277, 2014, DOI:10.32604/cmes.2014.098.261

    Abstract A widespread use of lasers is for the ablation of biological tissue, in particular for dermal applications involving the removal of cancerous tissue, skin spots, aged skin and wrinkles. For a laser to ablate tissue, the power intensity must be sufficiently high to induce vaporization/burning of the target material. However, if performed improperly, the process can cause excessive microscale thermal injuries to surrounding healthy tissue. This motivates the present work, which attempts to develop and assemble simple models for the primary heat transfer mechanisms that occur during the process. First, in order to qualitatively understand the system, the terms that… More >

  • Open Access


    Molecular Dynamics Simulations of Ions Diffusion in Carbon Nanotubes Embedded in Cell Membrane

    Qing Song Tu1, Michelle Lee2, Samuel Zhang2, Shaofan Li1

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.3, pp. 247-259, 2014, DOI:10.32604/cmes.2014.098.247

    Abstract In this paper, we present molecular dynamics simulations of diffusion of Na+, K+, and Cl- ions through the single-walled carbon nanotubes(SWCNTs) that are embedded into the membrane of cells in aqueous solutions. A simplified atomic cell model that considers bilayer membranes is employed to study the transportation of ions inside CNTs. The simulated results indicate that the diffusion properties of ions and selectivity of CNT with respect to ions are affected by biological complexity of the cell membrane. We have found that the ion diffusion only occurs in the CNTs with chirality higher than (8, 8), which is bigger than… More >

  • Open Access


    Design Evaluation of a Particle Bombardment System Used to Deliver Substances into Cells

    Eduardo M. B. Campello1,2, Tarek I. Zohdi3

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.2, pp. 221-245, 2014, DOI:10.3970/cmes.2014.098.221

    Abstract This work deals with the bombardment of a stream of particles possessing varying mean particle size, velocity and aspect ratio into a cell that has fixed (known) compliance characteristics. The particles are intended to penetrate the cell membrane causing zero or minimum damage and deliver foreign substances (which are attached to their surfaces) to the interior of the cell. We adopt a particle-based (discrete element method) computational model that has been recently developed by the authors to describe both the incoming stream of particles and the cell membrane. By means of parametric numerical simulations, treating the stream’s mean particle size,… More >

  • Open Access


    Geometrical Modeling of Cell Division and Cell Remodeling Based on Voronoi Tessellation Method

    Liqiang Lin1, Xianqiao Wang2, Xiaowei Zeng1,3

    CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.2, pp. 203-220, 2014, DOI:10.3970/cmes.2014.098.203

    Abstract The Voronoi tessellation is employed to describe cellular patterns and to simulate cell division and cell remodeling in epithelial tissue. First, Halton sequence is utilized to generate the random generators of Voronoi cell points. The centroidal Voronoi cell center is obtained by probabilistic Lloyd's method and polygonal structure of cell distribution is modeled. Based on the polygonal shape of cells, the instantaneous mechanism of cell division is applied to simulate the cell proliferation and remodeling. Four kinds of single-cell division algorithms are designed with the consideration of cleavage angle. From these simulations, we find that cell topological structure varies case… More >

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