Michael Yu Wang¹, Xiaoming Wang²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 373-396, 2004, DOI:10.3970/cmes.2004.006.373

Abstract This paper addresses the problem of structural shape and topology optimization. A level set method is adopted as an alternative approach to the popular homogenization based methods. The paper focuses on four areas of discussion: (1) The level-set model of the structure’s shape is characterized as a region and global representation; the shape boundary is embedded in a higher-dimensional scalar function as its “iso-surface.” Changes of the shape and topology are governed by a partial differential equation (PDE). (2) The velocity vector of the Hamilton-Jacobi PDE is shown to be naturally related to the shape derivative from the classical shape… More >

Dongwoo Sheen¹, Sangwon Seo², Jinwoo Cho³

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.1, pp. 21-30, 2003, DOI:10.3970/cmes.2003.004.021

Abstract The reconstructing optimal microstructures of given homogenized coefficients of steady diffusion equation is studied. In the reconstruction, the governing equation of level set function is approximated by adding viscosity term and the numerical procedure for the evolution of the level set function for the solution is examined. The numerical experiments of reconstruction are obtained by applying a finite element method with locally fitted mesh. More >

S. Oukach^1,2,3, H. Hamdi², M. El Ganaoui⁴, B. Pateyron¹

FDMP-Fluid Dynamics & Materials Processing, Vol.8, No.2, pp. 173-196, 2012, DOI:10.3970/fdmp.2012.008.173

Abstract The splat formation is one of the basic processes in thermal spray coatings. The performance of these coatings is strongly related to the process of spreading and solidification of molten droplets. The aim of the present paper is to simulate the fluid flow, heat transfer and phase-change that occur when a micrometric molten droplet impacts onto a rigid substrate and to examine the effect of the substrate conditions, such as initial temperature and material on the solidification time and spreading process. The effect of thermal contact resistance is also investigated. The simulation model used is based on the Navier-Stokes equations… More >

Xiaofeng Yang¹, Ashley J. James^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.3, No.1, pp. 65-96, 2007, DOI:10.3970/fdmp.2007.003.065

Abstract An arbitrary Lagrangian-Eulerian (ALE) method for interfacial flows with insoluble surfactants is presented. The interface is captured using a coupled level set and volume of fluid method, which takes advantage of the strengths of both the level set method and the volume of fluid method. By directly tracking the surfactant mass, the method conserves surfactant mass, and prevents surfactant from diffusing off the interface. Interfacial area is also tracked. To accurately approximate the interfacial area, the fluid interface is reconstructed using piece-wise parabolas. The surfactant concentration, which determines the local surface tension through an equation of state, is then computed… More >

Cosmina S. Hogea¹, Bruce T. Murray¹, James A. Sethian^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 109-130, 2005, DOI:10.3970/fdmp.2005.001.109

Abstract A computational framework for simulating growth and transport in biological materials based on continuum models is proposed. The advantages of the finite difference methodology employed are generality and relative simplicity of implementation. The Cartesian mesh/level set method developed here provides a computational tool for the investigation of a host of transport-based tissue/tumor growth models, that are posed as free or moving boundary problems and may exhibit complicated boundary evolution including topological changes. The methodology is tested here on a widely studied "incompressible flow" type tumor growth model with a numerical implementation in two dimensions; comparisons with results obtained from a… More >

Edwin Jim ´enez¹, Mark Sussman², Mitsuhiro Ohta³

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.2, pp. 97-108, 2005, DOI:10.3970/fdmp.2005.001.097

Abstract The aim of this paper is to utilize a numerical model to compute bubble motion in quiescent Newtonian and viscoelastic liquids. For our numerical method, we use a coupled level set and volume-of-fluid method with a second order treatment for the jump conditions related to surface tension. We investigate axisymmetric gas-liquid systems with large density and viscosity ratios as well as buoyancy-driven flows with complex changes in topology. We present comparisons to previous computational results as well as experimental results. More >

Chen Shen^1,*, Youping Chen¹, Bing Chen¹, Jingming Xie¹

CMC-Computers, Materials & Continua, Vol.61, No.1, pp. 379-397, 2019, DOI:10.32604/cmc.2019.04883

Abstract Continuous material processing operations like printing and textiles manufacturing are conducted under highly variable conditions due to changes in the environment and/or in the materials being processed. As such, the processing parameters require robust real-time adjustment appropriate to the conditions of a nonlinear system. This paper addresses this issue by presenting a hybrid feedforward-feedback nonlinear model predictive controller for continuous material processing operations. The adaptive feedback control strategy of the controller augments the standard feedforward control to ensure improved robustness and compensation for environmental disturbances and/or parameter uncertainties. Thus, the controller can reduce the need for manual adjustments. The controller… More >

Junjia Chen¹, Wei Lu^1,2,*, Yuileong Yeung¹, Yingjie Xue¹, Xianjin Liu¹, Cong Lin^1,3, Yue Zhang⁴

CMC-Computers, Materials & Continua, Vol.55, No.2, pp. 201-211, 2018, DOI:10.3970/cmc.2018.01781

Abstract In recent years, binary image steganography has developed so rapidly that the research of binary image steganalysis becomes more important for information security. In most state-of-the-art binary image steganographic schemes, they always find out the flippable pixels to minimize the embedding distortions. For this reason, the stego images generated by the previous schemes maintain visual quality and it is hard for steganalyzer to capture the embedding trace in spacial domain. However, the distortion maps can be calculated for cover and stego images and the difference between them is significant. In this paper, a novel binary image steganalytic scheme is proposed,… More >

A.J. Shaw¹ and P.D. Gosling^1,2

CMC-Computers, Materials & Continua, Vol.18, No.3, pp. 237-270, 2010, DOI:10.3970/cmc.2010.018.237

Abstract This article has no abstract. More >

Heng-Cheng Lin¹, Chieh Kung², Rong-Sheng Chen¹, Gin-Tiao Liang¹

CMC-Computers, Materials & Continua, Vol.3, No.2, pp. 55-64, 2006, DOI:10.3970/cmc.2006.003.055

Abstract Wafer level chip scale package (WLCSP) has been recognized providing clear advantages over traditional wire-bond package in relaxing the need of underfill while offering high density of I/O interconnects. Without the underfill, the solder joint reliability becomes more critical. Adding to the reliability concerns is the safety demand trend toward "green'' products on which unleaded material, e.g. lead-free solders, is required. The requirement of lead-free solders on the packages results in a higher reflow temperature profile in the package manufacturing process, in turn, complicating the reliability issue. This paper presents an optimization study, considering the fatigue reliability, for a wafer… More >