Yunpeng Ma¹, Lifeng Wang^{1, *}, Mingxu Yi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 89-108, 2017, DOI:10.3970/cmes.2017.113.086

Abstract In this paper, an analytical time domain formulation based on Ffowcs Williams-Hawkings (FW-H) equation is derived for the prediction of the acoustic velocity field generated by moving bodies. This provides the imposition of the Neumann boundary condition on a rigid scattering surface. In order to calculate the scattering sound pressure of the duct, a thin-body boundary element method (BEM) has been proposed. The radiate sound pressure is calculated using the acoustic analogy FW-H equation. The scattering effect of the duct wall on the propagation of the sound wave is presented using the thin-body BEM. Computational More >

K. Abe¹, H. Fujii¹, S. Yoshimura¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 71-87, 2017, DOI:10.3970/cmes.2017.113.068

Abstract Microscopic traffic simulations are useful for solving various traffic- related problems, e.g. traffic jams and accidents, local and global environmental and energy problems, maintaining mobility in aging societies, and evacuation plan- ning for natural as well as man-made disasters. The origin-destination (OD) matrix is often used as the input to represent traffic demands into traffic simulators. In this study, we propose an indirect method for estimating the OD matrix using a traffic simulator as an internal model. The proposed method is designed to output results that are consistent with the input of the simulator. The More >

Li Bin^1,2,3, Fang Hongyuan^1,2,3,*, He Wei⁴, Sun Bin¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 57-69, 2017, DOI:10.3970/cmes.2017.113.054

Abstract The cutter head will be stuck when the shield machine pass through the area existing anchor left by foundation construction of surrounding high-rise building. Subsurface excavation method is an efficient way to remove the existed anchor. In this paper, a three-dimensional finite element model is developed to study stability of cross-channel excavation. The time-spatial effects of arch crown settlement, intrados uplift and side wall horizontal convergence are analyzed according to different excavation size, lining thickness and lining order. The results show that the excavation size is the main factor to control the deformation of the More >

Subhankar Sen¹, Sanjay Mittal^{2, *}

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 35-55, 2017, DOI:10.3970/cmes.2017.113.033

Abstract The evolution of far wake of stationary elliptic cylinders with angle of attack is investigated for the unsteady flow at Re = 200 using a stabilized finite- element method. The Reynolds number, Re, is based on the major axis of cylinder and free-stream speed. Cylinder aspect ratios, AR considered are 0.2, 0.5 and 0.8 while the angle of attack, α varies from 0◦ to 90◦. With increasing α, the Karman or primary shedding frequency of each cylinder decreases monotonically while the primary wavelength and time-averaged as well as r.m.s. drag increase monoton- ically. The time-averaged… More >

Rongxing Duan¹, Yanni Lin¹, Longfei Hu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 17-34, 2017, DOI:10.3970/cmes.2017.113.015

Abstract Fault tolerant technology has greatly improved the reliability of modern systems on one hand and makes their failure mechanisms more complex on the other. The characteristics of dynamics of failure, diversity of distribution and epistemic uncertainty always exist in these systems, which increase the challenges in the reliability assessment of these systems significantly. This paper presents a novel reliability analysis framework for complex systems within which the failure rates of components are expressed in interval numbers. Specifically, it uses a dynamic fault tree (DFT) to model the dynamic fault behaviors and copes with the epistemic More >

A. Takahashi¹, T. Shibata², K. Motoyama³, K. Misaji⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.1, pp. 1-15, 2017, DOI:10.3970/cmes.2017.113.001

Abstract A method for reducing the damage to a structure caused by an earthquake namely, using laminated rubber for seismic isolation is proposed, and the vibration characteristics of the rubber (which minimizes the seismic response of the structure during an earthquake) is optimized. A method called “Equivalent Linear System using Restoring Force Model of Power Function Type” (PFT-ELS) is applied to nonlinear vibration analysis of the rubber. In that analysis, a building with 15 layers of the laminated rubber is modeled. The seismic response of the building is analyzed, and the usefulness of the laminated rubber More >

Dylan Conway¹, Daniele Mortari²

CMES-Computer Modeling in Engineering & Sciences, Vol.111, No.2, pp. 147-169, 2016, DOI:10.3970/cmes.2016.111.147

Abstract This paper presents a new method to estimate position from line-ofsight measurements to known targets when attitude is known. The algorithm has two stages. The first produces a closed-form unbiased estimate for position that does not account for the measurement error covariance. The second stage is iterative and produces an estimate of position that explicitly accounts for the measurement error covariance and the coupling between measurement error and sensor-to-target distance. The algorithm gives an accurate estimate of both position and the corresponding position error covariance and has a low computational cost. The computational complexity is O(n) More >

Jui-Hsiang Kao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 59-73, 2016, DOI:10.3970/cmes.2016.112.059

Abstract In this paper, a step approach method in the time domain is developed to calculate the radiated waves from an arbitrary obstacle pulsating with multiple frequencies. The computing scheme is based on the Boundary Integral Equation and derived in the time domain; thus, the time-harmonic Neumann boundary condition can be imposed. By the present method, the values of the initial conditions are set to zero, and the approach process is carried forward in a loop from the first time step to the last. At each time step, the radiated pressure on each element is updated. More >

Wei Wei^1,2, Qingsheng Yang^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 33-58, 2016, DOI:10.3970/cmes.2016.112.033

Abstract Chemo-mechanical coupling behavior of materials is a transformation process between mechanical and chemical energy. In this paper, based on the coupled chemo-mechanical constitutive equations and governing equations during isothermal process, the equivalent integral forms of chemo-mechanical coupling governing equations and corresponding finite element procedure are obtained by using Hamilton's principle. An isoparametric plane element for chemo-mechanical coupling is associated into ABAQUS finite element package through user element subroutine UEL. The numerical examples exhibit that the ionic concentration variation can cause mechanical deformation and mechanical action can produce redistribution of ionic concentration for hydrogels. It is More >

Yaping Zhang¹, Qifeng Fan², Leiting Dong^2,3, Satya N. Atluri⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.112, No.1, pp. 1-32, 2016, DOI:10.3970/cmes.2016.112.001

Abstract Similar to the very vast prior literature on analyzing laminated composite structures, "higher-order" and "layer-wise higher-order" plate and shell theories for functionally-graded (FG) materials and structures are also widely popularized in the literature of the past two decades. However, such higher-order theories involve (1) postulating very complex assumptions for plate/shell kinematics in the thickness direction, (2) defining generalized variables of displacements, strains, and stresses, and (3) developing very complex governing equilibrium, compatibility, and constitutive equations in terms of newly-defined generalized kinematic and generalized kinetic variables. Their industrial applications are thus hindered by their inherent complexity,… More >