Yixian Du^1,2,3,4, De Chen¹, Xiaobo Xiang¹, Qihua Tian¹, Yi Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.1, pp. 53-75, 2013, DOI:10.3970/cmes.2013.094.053

Abstract Topological design of continuum structures usually involves numerical instabilities, such as checkerboards and mesh-dependency, which degenerate the manufacturability, the efficiency and the robustness of the optimal design. This paper will propose a new topology optimization method to suppress numerical instabilities occurred in the topology optimization of continua, according to the principle of error amplifier and feedback control in the control system. The design variables associated with topological design are updated based on the Cellular Automata (CA) theory. A couple of typical numerical examples are used to demonstrate the effectiveness of the proposed method in effectively suppressing numerical instabilities occurred in… More >

Yonghua Zhou¹ , Xun Yang¹ , Chao Mi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.6, pp. 415-437, 2013, DOI:10.3970/cmes.2013.090.415

Abstract High-speed train transportation is organized in a way of globally centralized planning and locally autonomous adjustment with the real-time known positions, speeds and other state information of trains. The hierarchical integration architecture composed of top, middle and bottom levels is proposed based on model predictive control (MPC) for the real-time scheduling and control. The middle-level trajectory configuration and tractive force setpoints play a critical role in fulfilling the top-level scheduling commands and guaranteeing the controllability of bottomlevel train operations. In the middle-level MPC-based train operation planning, the continuous cellular automaton model of train movements is proposed to dynamically configure the… More >

Yonghua Zhou¹, Chao Mi¹, Xun Yang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.6, pp. 533-550, 2012, DOI:10.3970/cmes.2012.086.533

Abstract The cellular automaton (CA) model for traffic flow describes the restrictive vehicle movements using the distance headway (gap) between two adjacent vehicles. However, the autonomous and synergistic behaviors also exist in the vehicle movements. This paper makes an attempt to propose a microscopic traffic simulation model such that the feedback control behavior during the driving process is incorporated into the CA model. The acceleration, speed holding and deceleration are manipulated by the difference between the gap and the braking reference distance the driver perceives, which is generally observed in the realistic traffic. The braking reference distance is related to the… More >

Yonghua Zhou¹, Chao Mi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.1, pp. 1-22, 2012, DOI:10.3970/cmes.2012.083.001

Abstract Cellular automata (CAs), model the dynamics of complex systems as the state update of cells restricted from their own neighbors. This paper regards the tempo-spatial constraints as dummy neighborhoods of cells for train movement, such as scheduled movement authority and speed restriction, equivalent to the maximum displacements during the future certain time steps and each time step, respectively. Under the framework of CA modeling, this paper attempts to propose an improved CA model for moving-block railway network which incorporates the tempo-spatial constraints to capture the restrictive, synergistic and autonomous dynamics. We divide the one-dimensional cell lattice into several segments, called… More >

R. Zakhama^1,2,3, M.M. Abdalla², H. Smaoui^1,3, Z. Gürdal²

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 1-26, 2009, DOI:10.3970/cmes.2009.051.001

Abstract A multigrid accelerated cellular automata algorithm for two and three dimensional continuum topology optimization problems is presented. The topology optimization problem is regularized using the traditional SIMP approach. The analysis rules are derived from the principle of minimum total potential energy, and the design rules are derived based on continuous optimality criteria interpreted as local Kuhn-Tucker conditions. Three versions of the algorithm are implemented; a cellular automata based design algorithm, a baseline multigrid algorithm for analysis acceleration and a full multigrid integrated analysis and design algorithm. It is shown that the multigrid accelerated cellular automata scheme is a powerful tool… More >

Zhenjun Zhu, Chang Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 11-20, 2000, DOI:10.3970/cmes.2000.001.011

Abstract We present results on the development of an anisotropic crystalline etching simulation (ACES) program based on a new continuous Cellular Automata (CA) model, which provides improved spatial resolution and accuracy compared with the conventional and the stochastic CA \mbox{methods}. Implementation of a dynamic CA technique provides increased simulation speed and reduced memory requirement (5x). A first ACES software based on common personal computer platforms has been realized. Simulated results of etching match well with experiments. We have developed a new methodology to obtain the etch-rate diagram of anisotropic etching efficiently using both experimental and numerical techniques. More >

A.Z. Lorbiecka¹, R.Vertnik², H.Gjerkeš¹, G. Manojlovič², B.Senčič², J. Cesar², B.Šarler^1,3

CMC-Computers, Materials & Continua, Vol.8, No.3, pp. 195-208, 2008, DOI:10.3970/cmc.2008.008.195

Abstract A numerical model is developed for the simulation of solidification grain structure formation (equiaxed to columnar and columnar to equiaxed transitions) during the continuous casting process of steel billets. The cellular automata microstructure model is combined with the macroscopic heat transfer model. The cellular automata method is based on the Nastac's definition of neighborhood, Gaussian nucleation rule, and KGT growth model. The heat transfer model is solved by the meshless technique by using local collocation with radial basis functions. The microscopic model parameters have been adjusted with respect to the experimental data for steel 51CrMoV4. Simulations have been carried out… More >

A.Z. Lorbiecka¹, B. Šarler^1,2

CMC-Computers, Materials & Continua, Vol.18, No.1, pp. 69-104, 2010, DOI:10.3970/cmc.2010.018.069

Abstract The aim of this paper is simulation of thermally induced liquid-solid dendritic growth in two dimensions by a coupled deterministic continuum mechanics heat transfer model and a stochastic localized phase change kinetics model that takes into account the undercooling, curvature, kinetic and thermodynamic anisotropy. The stochastic model receives temperature information from the deterministic model and the deterministic model receives the solid fraction information from the stochastic model. The heat transfer model is solved on a regular grid by the standard explicit Finite Difference Method (FDM). The phase-change kinetics model is solved by the classical Cellular Automata (CA) approach and a… More >