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  • Analysis of Naval Ship Evacuation Using Stochastic Simulation Models and Experimental Data Sets
  • Abstract The study of emergency evacuation in public spaces, buildings and large ships may present parallel characteristic in terms of complexity of the layout but there are also significant differences that can hindering passengers to reach muster stations or the lifeboats. There are many hazards on a ship that can cause an emergency evacuation, the most severe result in loss of lives. Providing safe and effective evacuation of passengers from ships in an emergency situation becomes critical. Recently, computer simulation has become an indispensable technology in various fields, among them, the evacuation models that recently evolved incorporating human behavioral factors. In…
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  • Numerical Study on Rock Breaking Mechanism of Supercritical CO2 Jet Based on Smoothed Particle Hydrodynamics
  • Abstract Supercritical carbon dioxide (Sc-CO2) jet rock breaking is a nonlinear impact dynamics problem involving many factors. Considering the complexity of the physical properties of the Sc-CO2 jet and the mesh distortion problem in dealing with large deformation problems using the finite element method, the smoothed particle hydrodynamics (SPH) method is used to simulate and analyze the rock breaking process by Sc-CO2 jet based on the derivation of the jet velocity-density evolution mathematical model. The results indicate that there exisits an optimal rock breaking temperature by Sc-CO2. The volume and length of the rock fracture increase with the rising of the…
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  • Multiresolution Isogeometric Topology Optimisation Using Moving Morphable Voids
  • Abstract A general and new explicit isogeometric topology optimisation approach with moving morphable voids (MMV) is proposed. In this approach, a novel multiresolution scheme with two distinct discretisation levels is developed to obtain high-resolution designs with a relatively low computational cost. Ersatz material model based on Greville abscissae collocation scheme is utilised to represent both the Young’s modulus of the material and the density field. Two benchmark examples are tested to illustrate the effectiveness of the proposed method. Numerical results show that high-resolution designs can be obtained with relatively low computational cost, and the optimisation can be significantly improved without introducing…
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  • Integral Transform Method for a Porous Slider with Magnetic Field and Velocity Slip
  • Abstract Current research is about the injection of a viscous fluid in the presence of a transverse uniform magnetic field to reduce the sliding drag. There is a slip-on both the slider and the ground in the two cases, for example, a long porous slider and a circular porous slider. By utilizing similarity transformation Navier-Stokes equations are converted into coupled equations which are tackled by Integral Transform Method. Solutions are obtained for different values of Reynolds numbers, velocity slip, and magnetic field. We found that surface slip and Reynolds number has a substantial influence on the lift and drag of long…
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  • Dimensionless Variation of Seepage in Porous Media with Cracks Stimulated by Low-Frequency Vibration
  • Abstract Pulse excitation or vibration stimulation was imposed on the low permeable formation with cracks to enhance the production or injection capacity. During that process, a coupling of wave-induced flow and initial flow in dual-porous media was involved. Researchers had done much work on the rule of wave propagation in fractured porous media, whereas attentions on the variation law of flow in developing low permeable formation with cracks under vibration stimulation were not paid. In this study, the effect of low-frequency vibration on the seepage in dual-porous media was examined for the application of wave stimulation technology in developing reservoirs with…
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  • A Lane Detection Method Based on Semantic Segmentation
  • Abstract This paper proposes a novel method of lane detection, which adopts VGG16 as the basis of convolutional neural network to extract lane line features by cavity convolution, wherein the lane lines are divided into dotted lines and solid lines. Expanding the field of experience through hollow convolution, the full connection layer of the network is discarded, the last largest pooling layer of the VGG16 network is removed, and the processing of the last three convolution layers is replaced by hole convolution. At the same time, CNN adopts the encoder and decoder structure mode, and uses the index function of the…
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  •   Views:162       Downloads:156        Download PDF
  • An Equivalent Strain Based Multi-Scale Damage Model of Concrete
  • Abstract A multi-scale damage model of concrete is proposed based on the concept of energy equivalent strain for generic two- or three-dimensional applications. Continuum damage mechanics serves as the framework to describe the basic damage variables, namely the tensile and compressive damage. The homogenized Helmholtz free energy is introduced as the bridge to link the micro-cell and macroscopic material. The crack propagation in micro-cells is modeled, and the Helmholtz free energy in the cracked micro-structure is calculated and employed to extract the damage evolution functions in the macroscopic material. Based on the damage energy release rates and damage consistent condition, the…
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  • Multi-Scale Damage Model for Quasi-Brittle Composite Materials
  • Abstract In the present paper, a hierarchical multi-scale method is developed for the nonlinear analysis of composite materials undergoing heterogeneity and damage. Starting from the homogenization theory, the energy equivalence between scales is developed. Then accompanied with the energy based damage model, the multi-scale damage evolutions are resolved by homogenizing the energy scalar over the meso-cell. The macroscopic behaviors described by the multi-scale damage evolutions represent the mesoscopic heterogeneity and damage of the composites. A rather simple structure made from particle reinforced composite materials is developed as a numerical example. The agreement between the fullscale simulating results and the multi-scale simulating…
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  • A Unified Dimensionless Parameter for Finite Element Mesh for Beams Resting on Elastic Foundation
  • Abstract Discretising a structure into elements is a key step in finite element (FE) analysis. The discretised geometry used to formulate an FE model can greatly affect accuracy and validity. This paper presents a unified dimensionless parameter to generate a mesh of cubic FEs for the analysis of very long beams resting on an elastic foundation. A uniform beam resting on elastic foundation with various values of flexural stiffness and elastic supporting coefficients subject to static load and moving load is used to illustrate the application of the proposed parameter. The numerical results show that (a) Even if the values of…
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  • On the Simulation of Fragmentation During the Process of Ceramic Tile Impacted by Blunt Projectile with SPH Method in LS-DYNA
  • Abstract Ceramics are extensively used in protective structures which are often subjected to projectile impacts. During an impact process of a ceramic target by a projectile, fragmentation occurs in both the target and the projectile. It is challenging to simulate such events and predict residual mass and velocity of the projectile. In this work, we attempt to use smoothed particle hydrodynamics (SPH) in LS-DYNA to reproduce fragmentation of the target and the projectile and predict residual mass and velocity of the projectile during a projectile impact of a ceramic target. SPH models for an alumina ceramic tile impacted by a blunt…
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  •   Views:175       Downloads:203        Download PDF
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