scholarly journals A Cellular Automaton Model for Pedestrians’ Movements Influenced by Gaseous Hazardous Material Spreading

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
J. Makmul
Keyword(s):  
Cellular Automaton ◽  
Numerical Experiments ◽  
Eikonal Equation ◽  
Arrival Time ◽  
Source Term ◽  
State Transition ◽  
Hazardous Material ◽  
Advection Diffusion ◽  
Moore Neighborhood ◽  
Ca Model

A cellular automaton (CA) model is proposed to simulate the egress of pedestrians while gaseous hazardous material is spreading. The advection-diffusion with source term is used to describe the propagation of gaseous hazardous material. It is incorporated into the CA model. The navigation field in our model is determined by the solution of the Eikonal equation. The state transition of a pedestrian relies on the arrival time of cells in the Moore neighborhood. Numerical experiments are investigated in a room with multiple exits, and their results are shown.

scholarly journals A Social Force Model for Pedestrians’ Movements Affected by Smoke Spreading

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
J. Makmul
Keyword(s):  
Numerical Experiments ◽  
Eikonal Equation ◽  
Source Term ◽  
Force Model ◽  
Social Force ◽  
Social Force Model ◽  
Advection Diffusion ◽  
Smoke Density ◽  
Negative Gradient

A social force (SF) model is proposed to simulate the egress of pedestrians while smoke is spreading. The advection-diffusion with source term is used to describe the propagation of smoke. It is incorporated into the SF model. The navigation field in our model is determined by the negative gradient of the solution of the Eikonal equation. It depends on the pedestrian and smoke density. Numerical experiments are performed in a room with multiple exits, and their results are shown.

scholarly journals A Cellular Automaton Model for a Pedestrian Flow Problem

2021 ◽  
Author(s):  
Jiri Felcman ◽  
Petr Kubera
Keyword(s):  
Cellular Automaton ◽  
Eikonal Equation ◽  
Flow Model ◽  
Time Discretization ◽  
Implicit Time ◽  
Two Dimensional ◽  
Pedestrian Flow ◽  
Finite Set ◽  
Ca Model ◽  
Volume Method

The evacuation phenomena in the two dimensional pedestrian flow model are simulated. The intended direction of the escape of pedestrians in panic situations is governed by the Eikonal equation of the pedestrian flow model. A new two-dimensional Cellular Automaton (CA) model is proposed for the simulation of the pedestrian flow. The solution of the Eikonal equation is used to define the probability matrix whose elements express the  probability of a pedestrian moving  in finite set of directions. The novelty of this paper lies in the construction of the density dependent probability matrix. The relevant evacuation scenarios are numerically solved. Predictions of the evacuation behavior of pedestrians, for various room geometries with multiple exists, are demonstrated. The mathematical model is numerically justified by comparison of CA approach with the Finite Volume Method for the space discretization and Discontinuous Galerkin Method for the implicit time discretization of pedestrian flow model.

scholarly journals Oscillating behaviour of the spectrum for a plasmonic problem in a domain with a rounded corner

2018 ◽  
Vol 52 (4) ◽  
pp. 1285-1313 ◽  
Author(s):  
Lucas Chesnel ◽  
Xavier Claeys ◽  
Sergei A. Nazarov
Keyword(s):  
Asymptotic Expansion ◽  
Eigenvalue Problem ◽  
Recent Work ◽  
Present Article ◽  
Error Estimates ◽  
Numerical Experiments ◽  
Source Term ◽  
Oscillatory Behaviour ◽  
Time Harmonic ◽  
Rounded Corner

We investigate the eigenvalue problem −div(σ∇u) = λu (P) in a 2D domain Ω divided into two regions Ω±. We are interested in situations where σ takes positive values on Ω+ and negative ones on Ω−. Such problems appear in time harmonic electromagnetics in the modeling of plasmonic technologies. In a recent work [L. Chesnel, X. Claeys and S.A. Nazarov, Asymp. Anal. 88 (2014) 43–74], we highlighted an unusual instability phenomenon for the source term problem associated with (P): for certain configurations, when the interface between the subdomains Ω± presents a rounded corner, the solution may depend critically on the value of the rounding parameter. In the present article, we explain this property studying the eigenvalue problem (P). We provide an asymptotic expansion of the eigenvalues and prove error estimates. We establish an oscillatory behaviour of the eigenvalues as the rounding parameter of the corner tends to zero. We end the paper illustrating this phenomenon with numerical experiments.

scholarly journals Cellular Automaton Modeling of Phase Transformation of U-Nb Alloys during Solidification and Consequent Cooling Process

2019 ◽  
Vol 38 (2019) ◽  
pp. 567-575 ◽  
Author(s):  
Qingfu Tang ◽  
Dong Chen ◽  
Bin Su ◽  
Xiaopeng Zhang ◽  
Hongzhang Deng ◽  
...  
Keyword(s):  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Optical Microscope ◽  
Phase Precipitation ◽  
Cooling Process ◽  
Dendrite Morphology ◽  
Ca Model ◽  
Measuring Experiment ◽  
Kinetics Of ◽  
Cast Microstructure

AbstractThe microstructure evolution of U-Nb alloys during solidification and consequent cooling process was simulated using a cellular automaton (CA) model. By using this model, ϒ phase precipitation and monotectoid decomposition were simulated, and dendrite morphology of ϒ phase, Nb microsegregation and kinetics of monotectoid decomposition were obtained. To validate the model, an ingot of U-5.5Nb (wt.%) was produced and temperature measuring experiment was carried out. As-cast microstructure at different position taken from the ingot was investigated by using optical microscope and SEM. The effect of cooling rate on ϒ phase precipitation and monotectoid decomposition of U-Nb alloys was also studied. The simulated results were compared with the experimental results and the capability of the model for quantitatively predicting the microstructure evolution of U-Nb alloys during solidification and consequent cooling process was assessed.

A Cellular Automaton Model and its Application on Emotional Infections

2014 ◽  
Author(s):  
Zhao Liu ◽  
Huan Zhang ◽  
Taide Tan ◽  
Changxiong Qin ◽  
Jing Fan
Keyword(s):  
Theoretical Analysis ◽  
Organizational Behavior ◽  
Cellular Automaton ◽  
Positive Emotion ◽  
Positive Emotions ◽  
Emotional Contagion ◽  
Cellular Automaton Model ◽  
Reaction Process ◽  
Probabilistic Theory ◽  
Ca Model

Emotional contagion has been a focus problem in the current fields of psychology and organizational behavior. Based on the theoretical analysis of the emotional contagion mechanisms and probabilistic theory, a cellular automaton (CA) model has been proposed to simulate the process of emotional contagion. And with the help of this CA model, we study the gross features of employees’ positive emotions in the evolution of emotional contagion and explore the effects of employees’ ability to transport emotion susceptibility and intimacy on the reaction process. The results indicate that employees’ ability to transport positive emotion susceptibility and intimacy are positive related to the emotional contagion between employees.

scholarly journals Characterization of the Evolution of Nonlinear Uniform Cellular Automata in the Light of Deviant States

2011 ◽  
Vol 2011 ◽  
pp. 1-16 ◽  
Author(s):  
Pabitra Pal Choudhury ◽  
Sudhakar Sahoo ◽  
Mithun Chakraborty
Keyword(s):  
Cellular Automata ◽  
Cellular Automaton ◽  
Boolean Functions ◽  
State Transition ◽  
The State ◽  
Transition Diagram ◽  
One Dimensional ◽  
State Transition Diagram ◽  
Linear Rule

Dynamics of a nonlinear cellular automaton (CA) is, in general asymmetric, irregular, and unpredictable as opposed to that of a linear CA, which is highly systematic and tractable, primarily due to the presence of a matrix handle. In this paper, we present a novel technique of studying the properties of the State Transition Diagram of a nonlinear uniform one-dimensional cellular automaton in terms of its deviation from a suggested linear model. We have considered mainly elementary cellular automata with neighborhood of size three, and, in order to facilitate our analysis, we have classified the Boolean functions of three variables on the basis of number and position(s) of bit mismatch with linear rules. The concept of deviant and nondeviant states is introduced, and hence an algorithm is proposed for deducing the State Transition Diagram of a nonlinear CA rule from that of its nearest linear rule. A parameter called the proportion of deviant states is introduced, and its dependence on the length of the CA is studied for a particular class of nonlinear rules.

A cellular automaton simulation of W–Ni alloy solidification in laser solid forming process

2017 ◽  
Vol 02 (04) ◽  
pp. 1750016
Author(s):  
Haiou Yang ◽  
Lei Wei ◽  
Xin Lin
Keyword(s):  
Cellular Automaton ◽  
Laser Remelting ◽  
Dimensional Model ◽  
Forming Process ◽  
Microstructure Simulation ◽  
Melt Pool ◽  
Laser Solid Forming ◽  
Ni Alloy ◽  
Ca Model ◽  
Metallurgy Process

An alloy cellular automaton (CA) model is developed for the microstructure simulation in directional solidification and laser solid forming (LSF) process. The CA model's capture rule was modified by a limited neighbor solid fraction (LNSF) method. A multiscale two-dimensional model is presented for simulating laser remelting process, which is the same as LSF without the addition of metallic powders into melt pool. The metallurgy process in melt pool was simulated, including temperature distribution, pool shape and solidification of microstructure. The microstructure evolution of tungsten–nickel alloy (W–Ni) during LSF is also simulated by present CA model.

A NEW CELLULAR AUTOMATON MODEL FOR TRAFFIC FLOW WITH DIFFERENT PROBABILITY FOR DRIVERS

2007 ◽  
Vol 18 (05) ◽  
pp. 773-782 ◽  
Author(s):  
H. B. ZHU ◽  
H. X. GE ◽  
S. Q. DAI
Keyword(s):  
Cellular Automaton ◽  
Traffic Flow ◽  
Metastable State ◽  
Maximum Flow ◽  
Traffic Model ◽  
Fundamental Diagram ◽  
Density Dependent ◽  
Spontaneous Formation ◽  
Traffic Jams ◽  
Ca Model

Based on the Nagel–Schreckenberg (NaSch) model of traffic flow, a new cellular automaton (CA) traffic model is proposed to simulate microscopic traffic flow. The probability p is a variable which contains a randomly selected term for each individual driver and a density-dependent term which is the same for all drivers. When the rational probability p is obtained, the larger value of maximum flow which is close to the observed data can be reached compared with that obtained from the NaSch model. The fundamental diagram obtained by simulation shows the ability of this modified CA model to capture the essential features of traffic flow, e.g., the spontaneous formation of traffic jams and appearance of the metastable state. These indicate that the presented model is more reasonable and realistic.

Cellular Automaton Simulation of Microstructure Evolution for Friction Stir Blind Riveting

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Avik Samanta ◽  
Ninggang Shen ◽  
Haipeng Ji ◽  
Weiming Wang ◽  
Jingjing Li ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Cellular Automaton ◽  
Microstructure Evolution ◽  
Numerical Approach ◽  
Dislocation Dynamics ◽  
Grain Structure ◽  
Workpiece Material ◽  
Friction Stir ◽  
Ca Model

Friction stir blind riveting (FSBR) process offers the ability to create highly efficient joints for lightweight metal alloys. During the process, a distinctive gradient microstructure can be generated for the work material near the rivet hole surface due to high-gradient plastic deformation and friction. In this work, discontinuous dynamic recrystallization (dDRX) is found to be the major recrystallization mechanism of aluminum alloy 6111 undergoing FSBR. A cellular automaton (CA) model is developed for the first time to simulate the evolution of microstructure of workpiece material during the dynamic FSBR process by incorporating main microstructure evolution mechanisms, including dislocation dynamics during severe plastic deformation, dynamic recovery, dDRX, and subsequent grain growth. Complex thermomechanical loading conditions during FSBR are obtained using a mesh-free Lagrangian particle-based smooth particle hydrodynamics (SPH) method, and are applied in the CA model to predict the microstructure evolution near the rivet hole. The simulation results in grain structure agree well with the experiments, which indicates that the important characteristics of microstructure evolution during the FSBR process are well captured by the CA model. This study presents a novel numerical approach to model and simulate microstructure evolution undergoing severe plastic deformation processes.

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