Simulation of Dynamic Recrystallization Using Cellular Automaton Method
Institute of Scientific and Technical Information of China (English)
XIAO Hong; XIE Hong-biao; YAN Yan-hong; Jun YANAGIMOTO
2004-01-01
A new modeling approach that couples fundamental metallurgical principles of dynamical recrystallization with the cellular automaton method was developed to simulate the microstructural evolution linking with the plastic flow behavior during thermomechanical processing. The driving force for the nucleation and growth of dynamically recrystallized grain is the volume free energy due to the stored dislocation density of a deformation matrix. The growth terminates the impingement. The model is capable of simulating kinetics, microstructure and texture evolution during recrystallization. The predictions of microstructural evolution agree with the experimental results.
Cellular Automaton Simulation of Evacuation Process in Story
Institute of Scientific and Technical Information of China (English)
MA Chang-Qun; ZHENG Rong-Sen; GAO Chun-Yuan; QIU Bing; DENG Min-Yi; KONC Ling-Jiang; LIU Mu-Ren
2008-01-01
Computer simulations on the evacuation process in a story are launched with cellular automaton in this article. The story is composed of five rooms and one corridor. Influence of various parameters on the evacuation process is investigated. It shows that the width of the door of rooms has little influence but the width of the corridor and themaximum velocity of the pedestrian have great influence on the time for evacuation. The relation between evacuation time and the width of corridor is found as tc ∝ W-.0.84. It is also found that appropriate shape of the room is helpful to evacuation.
Institute of Scientific and Technical Information of China (English)
ZHANG Lin; ZHANG Cai-bei
2006-01-01
Two-dimensional cellular automaton(CA) simulations of phase transformations of binary alloys during solidification were reported. The modelling incorporates local concentration and heat changes into a nucleation or growth function, which is utilized by the automaton in a probabilistic fashion. These simulations may provide an efficient method of discovering how the physical processes involved in solidification processes dynamically progress and how they interact with each other during solidification. The simulated results show that the final morphology during solidification is related with the cooling conditions. The established model can be used to evaluate the phase transformation of binary alloys during solidification.
Simulation of plant communities with a cellular automaton
Energy Technology Data Exchange (ETDEWEB)
Gassmann, F. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1999-08-01
With a modelling approach based on cellular automata, five observed types of plant development can be simulated. In addition, the proposed model shows a strong tendency towards the formation of patches and a high degree of dynamical and structural instability leading to limits of predictability for the asymptotic solution chosen by the system among several possible metastable patterns (multistability). Further, external fluctuations can be shown to have advantages for certain plant types. The presented model unifies the fundamental dichotomy in vegetation dynamics between determinism (understood as predictability) and disorder (chance effects) by showing the outcome of both classical theories as special cases. (author) 2 figs., 4 refs.
Simulation of Magnesium Alloy AZ91D Microstructure Using Modified Cellular Automaton Method
Institute of Scientific and Technical Information of China (English)
HUO Liang; LI Bin; SHI Yufeng; XU Qingyan; HAN Zhiqiang; LIU Baicheng
2009-01-01
A two-dimensional modified cellular automaton model was developed to simulate the solidification process of magnesium alloy, The stochastic nucleation, solute redistribution, and growth anisotropy effects were taken into account in the present model. The model was used to simulate the grain size of magnesium alloy AZ91D for various cooling rates during the solidification process. To quantitatively validate the current model, metallographic expedments were carded out on specimens obtained from sand mold AZ91D step castings. The metallographic results agree well with the prediction results. The current model can be used to accurately predict the grain sizes of cast AZ91D magnesium alloy.
Cellular Automaton Simulation For Volume Changes Of Solidifying Nodular Cast Iron
Directory of Open Access Journals (Sweden)
Burbelko A.
2015-09-01
Full Text Available Volume changes of the binary Fe-C alloy with nodular graphite were forecast by means of the Cellular Automaton Finite Differences (CA-FD model of solidification. Simulations were performed in 2D space for differing carbon content. Dependences of phase density on temperature were considered in the computations; additionally density of the liquid phase and austenite were deemed as a function of carbon concentration. Changes of the specific volume were forecast on the base of the phase volume fractions and changes of phase density. Density of modeled material was calculated as weighted average of densities of each phase.
Simulation of emotional contagion using modified SIR model: A cellular automaton approach
Fu, Libi; Song, Weiguo; Lv, Wei; Lo, Siuming
2014-07-01
Emotion plays an important role in the decision-making of individuals in some emergency situations. The contagion of emotion may induce either normal or abnormal consolidated crowd behavior. This paper aims to simulate the dynamics of emotional contagion among crowds by modifying the epidemiological SIR model to a cellular automaton approach. This new cellular automaton model, entitled the “CA-SIRS model”, captures the dynamic process ‘susceptible-infected-recovered-susceptible', which is based on SIRS contagion in epidemiological theory. Moreover, in this new model, the process is integrated with individual movement. The simulation results of this model show that multiple waves and dynamical stability around a mean value will appear during emotion spreading. It was found that the proportion of initial infected individuals had little influence on the final stable proportion of infected population in a given system, and that infection frequency increased with an increase in the average crowd density. Our results further suggest that individual movement accelerates the spread speed of emotion and increases the stable proportion of infected population. Furthermore, decreasing the duration of an infection and the probability of reinfection can markedly reduce the number of infected individuals. It is hoped that this study will be helpful in crowd management and evacuation organization.
Mesoscale simulation of discontinuous dynamic recrystallization using the cellular automaton method
Institute of Scientific and Technical Information of China (English)
Baojun YU; Xiaojun GUAN; Lijun WANG; Qingkai ZENG; Qianqian LIU; Yu CAO
2011-01-01
A dynamic recrystallization (DRX) cellular automaton (CA) model that can mark the microstructure with DRX circle was developed.The effects of initial grain size on the stress-strain curve,mean grain size and DRX fraction were mainly investigated,and the simulated results were compared with those obtained from previous researches.The results show that the shape of the stress-strain curve is sensitive,while the stress and mean grain size at the steady state are insensitive to the initial grain size.The transition from a multiple-peak stress-strain curve to a single-peak one can be explained by variations in DRX circle fraction,and the initial grain size to make this transition is between 70 and 80 μm.
Cellular automaton for chimera states
García-Morales, Vladimir
2016-01-01
A minimalistic model for chimera states is presented. The model is a cellular automaton (CA) which depends on only one adjustable parameter, the range of the nonlocal coupling, and is built from elementary cellular automata and the majority (voting) rule. This suggests the universality of chimera-like behavior from a new point of view: Already simple CA rules based on the majority rule exhibit this behavior. After a short transient, we find chimera states for arbitrary initial conditions, the...
Institute of Scientific and Technical Information of China (English)
2012-01-01
A cellular automaton （CA）-finite element （FE） model and a phase field （PF）-FE model were used to simulate equiaxed dendritic growth during the solidification of hexagonal metals. In the CA-FE model, the conservation equations of mass and energy were solved in order to calculate the temperature field, solute concentration, and the dendritic growth morphology. CA-FE simulation results showed reasonable agreement with the previously reported experimental data on secondary dendrite arm spacing （SDAS） vs cooling rate. In the PF model, a PF variable was used to distinguish solid and liquid phases similar to the conventional PF models for solidification of pure materials. Another PF variable was considered to determine the evolution of solute concentration. Validation of both models was performed by comparing the simulation results with the analytical model developed by Lipton-Glicksman-Kurz （LGK）, showing quantitatively good agreement in the tip growth velocity at a given melt undercooling. Application to magnesium alloy AZ91 （approximated with the binary Mg-8.9 wt% AI） illustrates the difficulty of modeling dendrite growth in hexagonal systems using CA-FE regarding mesh-induced anisotropy and a better performance of PF-FE in modeling multiple arbitrarily-oriented dendrites growth.
Simulation of Microstructure during Laser Rapid Forming Solidification Based on Cellular Automaton
Directory of Open Access Journals (Sweden)
Zhi-jian Wang
2014-01-01
Full Text Available The grain microstructure of molten pool during the solidification of TC4 titanium alloy in the single point laser cladding was investigated based on the CAFE model which is the cellular automaton (CA coupled with the finite element (FE method. The correct temperature field is the prerequisite for simulating the grain microstructure during the solidification of the molten pool. The model solves the energy equation by the FE method to simulate the temperature distribution in the molten pool of the single point laser cladding. Based on the temperature field, the solidification microstructure of the molten pool is also simulated with the CAFE method. The results show that the maximum temperature in the molten pool increases with the laser power and the scanning rate. The laser power has a larger influence on the temperature distribution of the molten pool than the scanning rate. During the solidification of the molten pool, the heat at the bottom of the molten pool transfers faster than that at the top of the molten pool. The grains rapidly grow into the molten pool, and then the columnar crystals are formed. This study has a very important significance for improving the quality of the structure parts manufactured through the laser cladding forming.
Akbari, Mostafa; Asadi, Parviz; Besharati Givi, MohammadKazem; Zolghadr, Parisa
2016-03-01
To predict the grain size and microstructure evolution during friction stir welding (FSW) of AZ91 magnesium alloy, a finite element model (FEM) is developed based on the combination of a cellular automaton model and the Kocks - Mecking and Laasraoui-Jonas models. First, according to the flow stress curves and using the Kocks - Mecking model, the hardening and recovery parameters and the strain rate sensitivity were calculated. Next, an FEM model was established in Deform-3D software to simulate the FSW of AZ91 magnesium alloy. The results of the FEM model are used in microstructure evolution models to predict the grain size and microstructure of the weld zone. There is a good agreement between the simulated and experimental microstructures, and the proposed model can simulate the dynamic recrystallization (DRX) process during FSW of AZ91 alloy. Moreover, microstructural properties of different points in the SZ as well as the effect of the w/v parameter on the grain size and microstructure are considered.
Cellular automaton for chimera states
García-Morales, Vladimir
2016-04-01
A minimalistic model for chimera states is presented. The model is a cellular automaton (CA) which depends on only one adjustable parameter, the range of the nonlocal coupling, and is built from elementary cellular automata and the majority (voting) rule. This suggests the universality of chimera-like behavior from a new point of view: Already simple CA rules based on the majority rule exhibit this behavior. After a short transient, we find chimera states for arbitrary initial conditions, the system spontaneously splitting into stable domains separated by static boundaries, some synchronously oscillating and the others incoherent. When the coupling range is local, nontrivial coherent structures with different periodicities are formed.
A Modified Sensitive Driving Cellular Automaton Model
Institute of Scientific and Technical Information of China (English)
GE Hong-Xia; DAI Shi-Qiang; DONG Li-Yun; LEI Li
2005-01-01
A modified cellular automaton model for traffic flow on highway is proposed with a novel concept about the variable security gap. The concept is first introduced into the original Nagel-Schreckenberg model, which is called the non-sensitive driving cellular automaton model. And then it is incorporated with a sensitive driving NaSch model,in which the randomization brake is arranged before the deterministic deceleration. A parameter related to the variable security gap is determined through simulation. Comparison of the simulation results indicates that the variable security gap has different influence on the two models. The fundamental diagram obtained by simulation with the modified sensitive driving NaSch model shows that the maximumflow are in good agreement with the observed data, indicating that the presented model is more reasonable and realistic.
Recurrence time statistics of landslide events simulated by a cellular automaton model
Piegari, Ester; Di Maio, Rosa; Avella, Adolfo
2014-05-01
The recurrence time statistics of a cellular automaton modelling landslide events is analyzed by performing a numerical analysis in the parameter space and estimating Fano factor behaviors. The model is an extended version of the OFC model, which is a paradigm for SOC in non-conserved systems, but it works differently from the original OFC model as a finite value of the driving rate is applied. By driving the system to instability with different rates, the model exhibits a smooth transition from a correlated to an uncorrelated regime as the effect of a change in predominant mechanisms to propagate instability. If the rate at which instability is approached is small, chain processes dominate the landslide dynamics, and power laws govern probability distributions. However, the power-law regime typical of SOC-like systems is found in a range of return intervals that becomes shorter and shorter by increasing the values of the driving rates. Indeed, if the rates at which instability is approached are large, domino processes are no longer active in propagating instability, and large events simply occur because a large number of cells simultaneously reach instability. Such a gradual loss of the effectiveness of the chain propagation mechanism causes the system gradually enter to an uncorrelated regime where recurrence time distributions are characterized by Weibull behaviors. Simulation results are qualitatively compared with those from a recent analysis performed by Witt et al.(Earth Surf. Process. Landforms, 35, 1138, 2010) for the first complete databases of landslide occurrences over a period as large as fifty years. From the comparison with the extensive landslide data set, the numerical analysis suggests that statistics of such landslide data seem to be described by a crossover region between a correlated regime and an uncorrelated regime, where recurrence time distributions are characterized by power-law and Weibull behaviors for short and long return times
Indian Academy of Sciences (India)
M R Varma; R Sasikumar; S G K Pillai; P K Nair
2001-06-01
A two-dimensional diffusion based model is developed to describe transformation of austenite into ferrite and pearlite under continuous cooling conditions. The nucleation of ferrite is assumed to occur over grain boundaries and the nucleation of pearlite is assumed to be taking place all over the grain and at growing ferrite–austenite interfaces, when the composition and temperature conditions are favourable. A cellular automaton algorithm, with transformation rules based on this model is used for the growth of ferrite and pearlite. Model predicted results for continuous cooling transformations are verified by comparing the model predicted microstructure features with the experimental measurements for two sets of plain carbon steels of different composition and austenite grain size. Using the model, it is possible to generate results like undercooling to start ferrite and pearlite transformations, which are difficult to obtain experimentally.
Energy Technology Data Exchange (ETDEWEB)
Marx, V.; Gottstein, G. [RWTH Aachen (Germany). Inst. fuer Metallkunde und Metallphysik
1998-12-31
A 3D model has been developed to simulate both primary static recrystallization and recovery of cold worked aluminum alloys. The model is based on a modified cellular automaton approach and incorporates the influence of crystallographic texture and microstructure in respect to both mechanisms mentioned above. The model takes into account oriented nucleation using an approach developed by Nes for aluminum alloys. The subsequent growth of the nuclei depends on the local stored energy of the deformed matrix (i.e. the driving pressure) and the misorientation between a growing nucleus and its surrounding matrix (i.e. the grain boundary mobility). This approach allows to model preferred growth of grains that exhibit maximum growth rate orientation relationship, e.g. for aluminum alloys a 40{degree}<111> relationship with the surrounding matrix. The model simulates kinetics, microstructure and texture development during heat treatment, discrete in time and space.
Cellular automatons applied to gas dynamic problems
Long, Lyle N.; Coopersmith, Robert M.; Mclachlan, B. G.
1987-01-01
This paper compares the results of a relatively new computational fluid dynamics method, cellular automatons, with experimental data and analytical results. This technique has been shown to qualitatively predict fluidlike behavior; however, there have been few published comparisons with experiment or other theories. Comparisons are made for a one-dimensional supersonic piston problem, Stokes first problem, and the flow past a normal flat plate. These comparisons are used to assess the ability of the method to accurately model fluid dynamic behavior and to point out its limitations. Reasonable results were obtained for all three test cases, but the fundamental limitations of cellular automatons are numerous. It may be misleading, at this time, to say that cellular automatons are a computationally efficient technique. Other methods, based on continuum or kinetic theory, would also be very efficient if as little of the physics were included.
A cellular automaton evacuation model based on mobile robot's behaviors
Institute of Scientific and Technical Information of China (English)
WENG WenGuo; YUAN HongYong; FAN WeiCheng
2007-01-01
The research of evacuation in some emergencies, e.g. fire, is of great benefit to reducing the injuries of persons. In this paper, a cellular automaton evacuation model based on mobile robot's behaviors is presented. Each person is treated as an intelligent mobile robot, and motor schemas, including move-to-goal, avoid-obstacle, swirl-obstacle and nervous-motion, drive persons to interact with their environment. The motor schemas are combined with cellular automaton theory, and an evacuation model is built. Evacuation simulation of persons with different move velocities shows that the presented model can predict accurately the evacuation phenomena in some emergencies.
Jin, Cheng-Jie; Wang, Wei; Jiang, Rui
2016-08-01
The proper setting of traffic signals at signalized intersections is one of the most important tasks in traffic control and management. This paper has evaluated the four-phase traffic signal plans at a four-leg intersection via cellular automaton simulations. Each leg consists of three lanes, an exclusive left-turn lane, a through lane, and a through/right-turn lane. For a comparison, we also evaluate the two-phase signal plan. The diagram of the intersection states in the space of inflow rate versus turning ratio has been presented, which exhibits four regions: In region I/II/III, congestion will propagate upstream and laterally and result in queue spillover with both signal plans/two-phase signal plan/four-phase signal plan, respectively. Therefore, neither signal plan works in region I, and only the four-phase signal plan/two-phase signal plan works in region II/III. In region IV, both signal plans work, but two-phase signal plan performs better in terms of average delays of vehicles. Finally, we study the diagram of the intersection states and average delays in the asymmetrical configurations.
A cellular automaton model adapted to sandboxes to simulate the transport of solutes
Lora, Boris; Donado, Leonardo; Castro, Eduardo; Bayuelo, Alfredo
2016-04-01
The increasingly use of groundwater sources for human consumption and the growth of the levels of these hydric sources contamination make imperative to reach a deeper understanding how the contaminants are transported by the water, in particular through a heterogeneous porous medium. Accordingly, the present research aims to design a model, which simulates the transport of solutes through a heterogeneous porous medium, using cellular automata. Cellular automata (CA) are a class of spatially (pixels) and temporally discrete mathematical systems characterized by local interaction (neighborhoods). The pixel size and the CA neighborhood were determined in order to reproduce accurately the solute behavior (Ilachinski, 2001). For the design and corresponding validation of the CA model were developed different conservative tracer tests using a sandbox packed heterogeneously with a coarse sand (size # 20 grain diameter 0,85 to 0,6 mm) and clay. We use Uranine and a saline solution with NaCl as a tracer which were measured taking snapshots each 20 seconds. A calibration curve (pixel intensity Vs Concentration) was used to obtain concentration maps. The sandbox was constructed of acrylic (caliber 0,8 cms) with 70 x 45 x 4 cms of dimensions. The "sandbox" had a grid of 35 transversal holes with a diameter of 4 mm each and an uniform separation from one to another of 10 cms. To validate the CA-model it was used a metric consisting in rating the number of correctly predicted pixels over the total per image throughout the entire test run. The CA-model shows that calibrations of pixels and neighborhoods allow reaching results over the 60 % of correctly predictions usually. This makes possible to think that the application of the CA- model could be useful in further researches regarding the transport of contaminants in hydrogeology.
Multidimensional traveling waves in the Allen–Cahn cellular automaton
International Nuclear Information System (INIS)
Ultradiscretization is a limiting procedure transforming a given difference equation into a cellular automaton. The cellular automaton constructed by this procedure preserves the essential properties of the original equation, such as the structure of exact solutions for integrable equations. In this article, a cellular automaton analog of the multidimensional Allen–Cahn equation which is not an integrable system is constructed by the ultradiscretization. Moreover, the traveling wave solutions for the resulting cellular automaton are given. The shape, behavior and stability of the solutions in ultradiscrete systems are similar to those in continuous systems. (paper)
Energy Technology Data Exchange (ETDEWEB)
Merdan, Ziya [Dept. of Physics, Kirikkale Univ. (Turkey); Bayirli, Mehmet [Dept. of Physics, Balikesir Univ. (Turkey); Ozturk, Mustafa Kemal [Dept. of Mineral Analysis and Technology, MTA, Ankara (Turkey)
2010-08-15
The fractals are obtained by using the model of diffusion-limited aggregation (DLA) for the lattice with L = 80, 120, and 160. The values of the fractal dimensions are compared with the results of former studies. As increasing the linear dimensions they are in good agreement with those. The fractals obtained by using the model of DLA are simulated on the Creutz cellular automaton by using a two-bit demon. The values computed for the critical temperature and the static critical exponents within the framework of the finite-size scaling theory are in agreement with the results of other simulations and theoretical values. (orig.)
A Computation in a Cellular Automaton Collider Rule 110
Martinez, Genaro J; McIntosh, Harold V
2016-01-01
A cellular automaton collider is a finite state machine build of rings of one-dimensional cellular automata. We show how a computation can be performed on the collider by exploiting interactions between gliders (particles, localisations). The constructions proposed are based on universality of elementary cellular automaton rule 110, cyclic tag systems, supercolliders, and computing on rings.
A Modified Cellular Automaton Model for Traffic Flow
Institute of Scientific and Technical Information of China (English)
葛红霞; 董力耘; 雷丽; 戴世强
2004-01-01
A modified cellular automaton model for traffic flow was proposed. A novel concept about the changeable security gap was introduced and a parameter related to the variable security gap was determined. The fundamental diagram obtained by simulation shows that the maximum flow more approaches to the observed data than that of the NaSch model, indicating that the presented model is more reasonable and realistic.
Fire Spread Model for Old Towns Based on Cellular Automaton
Institute of Scientific and Technical Information of China (English)
GAO Nan; WENG Wenguo; MA Wei; NI Shunjiang; HUANG Quanyi; YUAN Hongyong
2008-01-01
Old towns like Lijiang have enormous historic,artistic,and architectural value.The buildings in such old towns are usually made of highly combustible materials,such as wood and grass.If a fire breaks out,it will spread to multiple buildings,so fire spreading and controlling in old towns need to be studied.This paper presents a fire spread model for old towns based on cellular automaton.The cellular automaton rules were set according to historical fire data in empirical formulas.The model also considered the effects of climate.The simulation results were visualized in a geography information system.An example of a fire spread in Lijiang was investigated with the results showing that this model provides a realistic tool for predicting fire spread in old towns.Fire brigades can use this tool to predict when and how a fire spreads to minimize the losses.
The Algorithm of Continuous Optimization Based on the Modified Cellular Automaton
Directory of Open Access Journals (Sweden)
Oleg Evsutin
2016-08-01
Full Text Available This article is devoted to the application of the cellular automata mathematical apparatus to the problem of continuous optimization. The cellular automaton with an objective function is introduced as a new modification of the classic cellular automaton. The algorithm of continuous optimization, which is based on dynamics of the cellular automaton having the property of geometric symmetry, is obtained. The results of the simulation experiments with the obtained algorithm on standard test functions are provided, and a comparison between the analogs is shown.
Mathematical model for flood routing based on cellular automaton
Directory of Open Access Journals (Sweden)
Xin CAI
2014-04-01
Full Text Available Increasing frequency and severity of flooding have caused tremendous damage in China, requiring more essential countermeasures to alleviate the damage. In this study, the dynamic simulation property of a cellular automaton was used to make further progress in flood routing. In consideration of terrain’s influence on flood routing, we regarded the terrain elevation as an auxiliary attribute of a two-dimensional cellular automaton in path selection for flood routing and developed a mathematical model based on a cellular automaton. A numerical case of propagation of an outburst flood in an area of the lower Yangtze River was analyzed with both the fixed-step and variable-step models. The results show that the flood does not spread simultaneously in all directions, but flows into the lower place first, and that the submerged area grows quickly at the beginning, but slowly later on. The final submerged areas obtained from the two different models are consistent, and the flood volume balance test shows that the flood volume meets the requirement of the total volume balance. The analysis of the case shows that the proposed model can be a valuable tool for flood routing.
A New Cellular Automaton Model for Traffic Flow
Institute of Scientific and Technical Information of China (English)
YongtaoHU
1999-01-01
Establishment of effective traffic models to reveal fundamental traffic characteristics is an essential requirement in the design,planning and operation of transportation systems .In 1992 Nagel and Schreckenberg presented a cellular automaton model describing traffic flow of N cars on a single lane and applied it in the famous project TRANSIMS on transportation simulation.In this paper,the author proposes a new model for the same problem and gives a comparison of simulation results with the former ones.The comparison shows that the new model works better under the condition of high traffic density.
A cellular automaton model for a bridge traffic bottleneck
Institute of Scientific and Technical Information of China (English)
Shifa Xiao; Lingjiang Kong; Muren Liu
2005-01-01
A cellular automaton (CA) model is proposed in this paper to analyze a bridge traffic bottleneck. The simulation results with this model show that there are several phase transitions in the traffic average density, velocity and flow for each lane under a periodic boundary condition. An unstable phase in the traffic average density and velocity for the upstream and downstream lanes of the bridge is shown in a range of initial traffic densities. The critical points of the phase transitions and the phenomenon of the unstable phase found in the simulation are also explained with the mean-field theory.
Energy Technology Data Exchange (ETDEWEB)
Saiz, A. [Department of Applied Mathematics, Polytechnic University of Valencia, ETSGE School, Camino de Vera s/n, 46022 Valencia (Spain); Urchueguia, J.F. [Department of Applied Physics, Polytechnic University of Valencia, ETSII School, Camino de Vera s/n, 46022 Valencia (Spain); Martos, J. [Superior Technical School of Engineering, Department of Electronic Engineering, University of Valencia, Vicente Andres Estelles s/n, Burjassot 46100, Valencia (Spain)
2010-09-15
A discrete model characterizing heat and fluid flow in connection with thermal fluxes in a building is described and tested against experiment in this contribution. The model, based on a cellular automaton approach, relies on a set of a few quite simple rules and parameters in order to simulate the dynamic evolution of temperatures and energy flows in any water or brine based thermal energy distribution network in a building or system. Using an easy-to-record input, such as the instantaneous electrical power demand of the heating or cooling system, our model predicts time varying temperatures in characteristic spots and the related enthalpy flows whose simulation usually requires heavy computational tools and detailed knowledge of the network elements. As a particular example, we have applied our model to simulate an existing fan coil based hydronic heating system driven by a geothermal heat pump. When compared to the experimental temperature and thermal energy records, the outcome of the model coincides. (author)
A Realistic Cellular Automaton Model for Synchronized Traffic Flow
Institute of Scientific and Technical Information of China (English)
ZHAO Bo-Han; HU Mao-Bin; JIANG Rui; WU Qing-Song
2009-01-01
A cellular automaton model is proposed to consider the anticipation effect in drivers' behavior. It is shown that the anticipation effect can be one of the origins of synchronized traffic flow. With anticipation effect, the congested traffic flow simulated by the model exhibits the features of synchronized flow. The spatiotemporal patterns induced by an on-ramp are also consistent with the three-phaee traffic theory. Since the origin of synchronized flow is still controversial, our work can shed some light on the mechanism of synchronized flow.
Ito equations out of domino cellular automaton with efficiency parameters
Czechowski, Zbigniew
2011-01-01
Ito equations are derived for simple stochastic cellular automaton with parameters and compared with results obtained from the histogram method. Good agreement for various parameters supports wide applicability of the Ito equation as a macroscopic model.
A Programmable Hardware Cellular Automaton: Example of Data Flow Transformation
Samuel Charbouillot; Annie Pérez; Daniele Fronte
2008-01-01
We present an IP-core called PHCA which stands for programmable hardware cellular automaton. PHCA is a hardware implementation of a general purpose cellular automaton (CA) entirely programmable. The heart of this structure is a PE array with reconfigurable side links allowing the implementation of a 2D CA or a 1D CA. As an illustration of a PHCA program, we present the implementation of a symmetric cryptography algorithm called ISEA for Ising spin encryption algorithm. Indeed ISEA is based on...
International Nuclear Information System (INIS)
This paper reports on work in developing a cellular automaton (CA) model coupling with a topology deformation technique to simulate the microstructural evolution of 30Cr2Ni4MoV rotor steel during the high-temperature austenitizing and dynamic recrystallization (DRX). The state transition rules for simulating the normal grain growth was established based on the curvature-driven mechanism, thermodynamic driving mechanism and established based on the curvature-driven mechanism, thermodynamic driving mechanism and the lowest energy principle. To describe the compression effect on the topology of grain deformation more accurately, the update topology deformation model was proposed in which a cellular coordinate system and a material coordinate system were established separately. The cellular coordinate system remains unchangeable, but the material coordinate system and the corresponding grain boundary shape will change with deformation in the update topology deformation model. The effects of a wide range of thermomechanical parameters (e.g., temperature and strain rate) on the DRX kinetics and mean grain size were investigated. It was found that increasing the temperature and/or decreasing the strain rate can reduce the incubation period, and decreasing the temperature and/or increasing the strain rate can refine the DRX grain size. The simulation results are validated by comparing the experimental results.
A THREE-DIMENSIONAL CELLULAR AUTOMATON SIMULATION FOR DENDRITIC GROWTH%枝晶生长的三维元胞自动机模拟
Institute of Scientific and Technical Information of China (English)
江鸿翔; 赵九洲
2011-01-01
Perhaps dendrite is the most observed solidification microstructure of many metallic materials. The dendritic morphologies show a dominating effect on the performance of casting products. A lot of work has been carried out to investigate the formation mechanism of dendritic microstructure. It is found that the development of dendritic microstructures is a complicated process controlled by the interplay of many factors such as thermal and solute transfer, capillary etc. Cellular automaton (CA) can simulate the solidification process with a high computational efficiency, thus, attracts great attentions. In recent years, progress has been made on the two dimensional CA models for the solidification microstructure formation. But up to date researches on three dimensional CA model are very limited. A combined cellular automaton-finite difference (CA-FD) model for the three dimensional simulation of dendritic growth was developed in this paper. Simulations were performed to investigate the dendritic growth in an undercooled Al-Cu alloy as well as in a directionally solidified Al-Cu alloy. The numerical results showed clearly the development of the free dendrite in the under-cooled melt and the microstructure evolution in the directionally solidified alloy and agreed well with the theoretical predictions and the experimental results.%通过将元胞自动机和有限差分方法相耦合,建立了立方体系金属和合金枝晶生长的三维模型.应用该模型,模拟了Al-Cu合金过冷熔体中自由枝晶的生长和定向凝固条件下Al-Cu合金凝固组织演变过程.模拟结果清楚展现了过冷熔体中自由枝晶的生长过程和定向凝固过程中枝晶的形成与淹没,与理论预测和实验结果相吻合,表明所发展的模型能够较准确地描述立方体系金属和合金的凝固组织演变过程.
Gosálvez, M. A.; Ferrando, N.; Fedoryshyn, Y.; Leuthold, J.; McPeak, K. M.
2016-04-01
We combine experiments and simulations to study the acceleration of anisotropic etching of crystalline silicon at the mask-substrate interface, as a function of the coordination number of the substrate atoms located at the junction between obtuse-angled {1 1 1} facets and the mask layer. Atomistic simulations based on the use of the continuous cellular automaton (CCA) conclude that the interface atoms react faster with the etchant, thus initiating a step flow process that results in increased etch rates for the obtuse facets. By generating a wide range of complex cavities on high-index silicon wafers with a single-side, single-step etching, the comparison of the experimental and simulated results strongly indicates that the CCA method is suitable for accurately describing not only the development of micron-scaled structures but also, for the first time, the formation of submicron shapes. The study also describes the acceleration of obtuse facets formed through double-side etching, obtaining results in good agreement with previous experiments.
Quantum field as a quantum cellular automaton: The Dirac free evolution in one dimension
Energy Technology Data Exchange (ETDEWEB)
Bisio, Alessandro; D’Ariano, Giacomo Mauro; Tosini, Alessandro, E-mail: alessandro.tosini@unipv.it
2015-03-15
We present a quantum cellular automaton model in one space-dimension which has the Dirac equation as emergent. This model, a discrete-time and causal unitary evolution of a lattice of quantum systems, is derived from the assumptions of homogeneity, parity and time-reversal invariance. The comparison between the automaton and the Dirac evolutions is rigorously set as a discrimination problem between unitary channels. We derive an exact lower bound for the probability of error in the discrimination as an explicit function of the mass, the number and the momentum of the particles, and the duration of the evolution. Computing this bound with experimentally achievable values, we see that in that regime the QCA model cannot be discriminated from the usual Dirac evolution. Finally, we show that the evolution of one-particle states with narrow-band in momentum can be efficiently simulated by a dispersive differential equation for any regime. This analysis allows for a comparison with the dynamics of wave-packets as it is described by the usual Dirac equation. This paper is a first step in exploring the idea that quantum field theory could be grounded on a more fundamental quantum cellular automaton model and that physical dynamics could emerge from quantum information processing. In this framework, the discretization is a central ingredient and not only a tool for performing non-perturbative calculation as in lattice gauge theory. The automaton model, endowed with a precise notion of local observables and a full probabilistic interpretation, could lead to a coherent unification of a hypothetical discrete Planck scale with the usual Fermi scale of high-energy physics. - Highlights: • The free Dirac field in one space dimension as a quantum cellular automaton. • Large scale limit of the automaton and the emergence of the Dirac equation. • Dispersive differential equation for the evolution of smooth states on the automaton. • Optimal discrimination between the
International Nuclear Information System (INIS)
The cellular automaton (CA) method coupling fundamental metallurgical principles was used to simulate the initial microstructure and dynamic recrystallization (DRX) of 30Cr2Ni4MoV rotor steel. For the initial microstructure generation, reasonable transformation rules were established based on the thermodynamic mechanism, the activation energy and the curvature-driven mechanism. For the purposes of obtaining the material constants which were used in the CA model for DRX, including initial grain size, nucleation rate, softening parameter and activation energy, the hot deformation characteristics of 30Cr2Ni4MoV rotor steel were investigated by uniaxial hot compression tests on Gleeble-3500 machine. The effect of a wide range of thermomechanical processing parameters (temperature and strain rate) on the nucleation rate, the percentage of DRX and the final grain size were investigated. By comparison of the flow stress–strain curves and the metallographs, it was shown that the CA model coupling fundamental metallurgical principles can accurately simulate the microstructural evolution and the plastic flow behavior for 30Cr2Ni4MoV rotor steel at various deformation parameters
Coarse-grained cellular automaton for traffic systems
Krawczyk, Malgorzata J
2012-01-01
A coarse-grained cellular automaton is proposed to simulate traffic systems. There, cells represent road sections. A cell can be in two states: jammed or passable. Numerical calculations are performed for a piece of square lattice with open boundary conditions, for the same piece with some cells removed and for a map of a small city. The results indicate the presence of a phase transition in the parameter space, between two macroscopic phases: passable and jammed. The results are supplemented by exact calculations of the stationary probabilities of states for the related Kripke structure constructed for the traffic system. There, the symmetry-based reduction of the state space allows to partially reduce the computational limitations of the numerical method.
Metastable Congested States in Multisegment Traffic Cellular Automaton
Nishimura, Yutaka; Cheon, Taksu; Seba, Petr
2005-01-01
We investigate a simple multisegment cellular automaton model of traffic flow. With the introduction of segment-dependent deceleration probability, metastable congested states in the intermediate density region emerge, and the initial state dependence of the flow is observed. The essential feature of three-phased structure empirically found in real-world traffic flow is reproduced without elaborate assumptions.
EVOLUTION COMPLEXITY OF THEELEMENTARY CELLULAR AUTOMATON OF RULE 22
Institute of Scientific and Technical Information of China (English)
WangYi; JiangZhisong
2002-01-01
Cellular automata are the discrete dynamical systems of simple construction but with complex and varied behaviors. In this paper, the elementary cellular automaton of rule 22 is studied by the tools of formal language theory and symbolic dynamics. Its temporal evolution orbits are coarse-grained into evolution sequences and the evolution languages are defined. It is proved that for every n≥2 its width n evolution language is not regular.
Dirac Quantum Cellular Automaton from Split-step Quantum Walk
Mallick, Arindam
2015-01-01
Simulations of one quantum system by an other has an implications in realization of quantum machine that can imitate any quantum systems and solve problems that are not accessible to classical computers. One of the approach to engineer quantum simulations is to discretize the space-time degree of freedom in quantum dynamics and define the quantum cellular automata (QCA), a local unitary update rule on a lattice. Different models of QCA are constructed using different set of conditions which are not uniquely defined. The form of the operators in these model are not always in implementable configuration on an other system. Here, starting from a split-step discrete-time quantum walk (DTQW) which are uniquely defined for experimental implementation, we recover the Dirac quantum cellular automaton (DQCA). This will bridge the connection between Dirac equation(DE)-DQCA-DTQW and eliminate the explicit use of invariance, symmetries and limiting range of parameter to establish the connections. For a combination of par...
Cellular automaton-based position sensitive detector equalization
Energy Technology Data Exchange (ETDEWEB)
Ferrando, Nestor [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)], E-mail: nesferjo@upvnet.upv.es; Herrero, V.; Cerda, J.; Lerche, C.W.; Colom, R.J.; Gadea, R.; Martinez, J.D.; Monzo, J.M.; Mateo, F.; Sebastia, A.; Benlloch, J.M. [Grupo de Diseno de Sistemas Digitales, Instituto de Aplicaciones de las Tecnologias de la Informacion y de las Comunicaciones Avanzadas, Universidad Politecnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)
2009-06-01
Indirect position detectors based on scintillator crystals lack of spacial uniformity in their response. This happens due to crystal inhomogeneities and gain differences among the photomultiplier anodes. In order to solve this, PESIC, an integrated front-end for multianode photomultiplier based nuclear imaging devices was created. One of its main features is the digitally programmable gain adjustment for every photomultiplier output. On another front, cellular automata have been proved to be a useful method for dynamic system modeling. In this paper, a cellular automaton which emulates the behavior of the scintillator crystal, the photomultiplier and the front-end is introduced. Thanks to this model, an automatic energy-based calibration of the detector can be done by configuring the cellular automaton with experimental data and making it evolve up to an stable state. This can be useful as a precalibration method of the detector.
Investigating CTL mediated killing with a 3D cellular automaton.
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Frederik Graw
2009-08-01
Full Text Available Cytotoxic T lymphocytes (CTLs are important immune effectors against intra-cellular pathogens. These cells search for infected cells and kill them. Recently developed experimental methods in combination with mathematical models allow for the quantification of the efficacy of CTL killing in vivo and, hence, for the estimation of parameters that characterize the effect of CTL killing on the target cell populations. It is not known how these population-level parameters relate to single-cell properties. To address this question, we developed a three-dimensional cellular automaton model of the region of the spleen where CTL killing takes place. The cellular automaton model describes the movement of different cell populations and their interactions. Cell movement patterns in our cellular automaton model agree with observations from two-photon microscopy. We find that, despite the strong spatial nature of the kinetics in our cellular automaton model, the killing of target cells by CTLs can be described by a term which is linear in the target cell frequency and saturates with respect to the CTL levels. Further, we find that the parameters describing CTL killing on the population level are most strongly impacted by the time a CTL needs to kill a target cell. This suggests that the killing of target cells, rather than their localization, is the limiting step in CTL killing dynamics given reasonable frequencies of CTL. Our analysis identifies additional experimental directions which are of particular importance to interpret estimates of killing rates and could advance our quantitative understanding of CTL killing.
Three-level description of the domino cellular automaton
Czechowski, Zbigniew
2010-01-01
Inspired by the approach of kinetic theory of gases, a three-level description (microscopic, mesoscopic and macroscopic) of cellular automaton is presented. To provide an analytical treatment a simple domino cellular automaton with avalanches was constructed. Formulas concerning exact relations for density, clusters, avalanches and other parameters in an equilibrium state were derived. It appears that some relations are approximately valid for deviations from the equilibrium, so the adequate Ito equation could be constructed. The equation provides the time evolution description of some variable on the macroscopic level. The results also suggest a motive for applying of the procedure of construction of the Ito equation (from time series data) to natural time series.
A Programmable Hardware Cellular Automaton: Example of Data Flow Transformation
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Samuel Charbouillot
2008-01-01
Full Text Available We present an IP-core called PHCA which stands for programmable hardware cellular automaton. PHCA is a hardware implementation of a general purpose cellular automaton (CA entirely programmable. The heart of this structure is a PE array with reconfigurable side links allowing the implementation of a 2D CA or a 1D CA. As an illustration of a PHCA program, we present the implementation of a symmetric cryptography algorithm called ISEA for Ising spin encryption algorithm. Indeed ISEA is based on a 2D Ising spin lattice presenting random series of disordered spin configurations. The main idea of ISEA is to use this disorder to encrypt data. Efficiency of ISEA and PHCA implementation results are given.
Cellular automaton model of mass transport with chemical reactions
International Nuclear Information System (INIS)
The transport and chemical reactions of solutes are modelled as a cellular automaton in which molecules of different species perform a random walk on a regular lattice and react according to a local probabilistic rule. The model describes advection and diffusion in a simple way, and as no restriction is placed on the number of particles at a lattice site, it is also able to describe a wide variety of chemical reactions. Assuming molecular chaos and a smooth density function, we obtain the standard reaction-transport equations in the continuum limit. Simulations on one-and two-dimensional lattices show that the discrete model can be used to approximate the solutions of the continuum equations. We discuss discrepancies which arise from correlations between molecules and how these discrepancies disappear as the continuum limit is approached. Of particular interest are simulations displaying long-time behaviour which depends on long-wavelength statistical fluctuations not accounted for by the standard equations. The model is applied to the reactions a + b ↔ c and a + b → c with homogeneous and inhomogeneous initial conditions as well as to systems subject to autocatalytic reactions and displaying spontaneous formation of spatial concentration patterns. (author) 9 figs., 34 refs
Modeling Recrystallization of Austenite for C-Mn Steels during Hot Deformation by Cellular Automaton
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
By using a cellular automaton method, microstructure evolution of recrystallization in austenite during hot deformation was simulated for C-Mn steels. A model takes into account the influence of deformation temperature, strain, and strain rate on the dynamic recrystallization fraction, and the effect of the keeping time on the static recrystallization fraction based on a hot deformation test on a Gleeble-1500 simulator. In addition, the size changing of γ grains during continuous hot deformation was simulated by applying the model.
Directory of Open Access Journals (Sweden)
Wang Kuangfei
2010-02-01
Full Text Available The microstructural evolution of Ti-45 at.%Al alloy during directional solidification was simulated by applying a solute diffusion controlled solidification model. The obtained results have shown that under high thermal gradients the stable primary spacing can be adjusted via branching or competitive growth. For dendritic structures formed under a high thermal gradient, the secondary dendrite arms are developed not very well in many cases due to the branching mechanism under a constrained dendritic growth condition. Furthermore, it has been observed that, with increasing pulling velocity, there exists a cell/dendrite transition region consisting of cells and dendrites, which varies with the thermal gradient in a contradicting way, i.e. increase of the thermal gradient leading to the decrease of the range of the transition region. The simulations agree reasonably well with experiment results.
Lu, Lili; Ren, Gang; Wang, Wei; Chan, Ching-Yao; Wang, Jian
2016-10-01
At unsignalized crosswalks, interactions between pedestrians and vehicles often lead to traffic safety hazards due to absence of traffic control and unclear right-of-ways. To address this safety problem, there is a need to understand the interaction behaviors of pedestrians and vehicles that are complicated by a variety of traffic and roadway attributes. The prime objective of this study is to establish a reliable simulation model to represent the vehicle yielding and pedestrian crossing behaviors at unsignalized crosswalks in a realistic way. The model is calibrated with detailed behavioral data collected and extracted from field observations. The capability of the calibrated model in predicting the pedestrian-interaction events as well as estimating the driver yielding rate and pedestrian delay are also tested and demonstrated. Meanwhile, the traffic dynamics in the vicinity of the crosswalk can be meaningfully represented with simulation results based on the model. Moreover, with the definitions of the vehicle-pedestrian conflicts, the proposed model is capable to evaluate the pedestrian safety. Thereby, the simulation model has the potential to serve as a useful tool for assessing safety performance and traffic operations at existing facilities. Furthermore, the model can enable the evaluation of policy effectiveness and the selection of engineering treatments at unsignalized crosswalks to improve safety and efficiency of pedestrian crossing.
Cellular automaton model considering headway-distance effect
Institute of Scientific and Technical Information of China (English)
Hu Shou-Xin; Gao Kun; Wang Bing-Hong; Lu Yu-Feng
2008-01-01
This paper presents a cellular automaton model for single-lane traffic flow.On the basis of the Nagel-Schreckenberg (NS) model,it further considers the effect of headway-distance between two successive cars on the randomization of the latter one.In numerical simulations,this model shows the following characteristics.(1) With a simple structure,this model succeeds in reproducing the hysteresis effect,which is absent in the NS model.(2) Compared with the slow-tostart models,this model exhibits a local fundamental diagram which is more consistent to empirical observations.(3)This model has much higher efficiency in dissolving congestions compared with the so-called NS model with velocitydependent randomization (VDR model).(4) This model is more robust when facing traffic obstructions.It can resist much longer shock times and has much shorter relaxation times on the other hand.To summarize,compared with the existing models,this model is quite simple in structure,but has good characteristics.
A Modified Cellular Automaton Approach for Mixed Bicycle Traffic Flow Modeling
Xiaonian Shan; Zhibin Li; Xiaohong Chen; Jianhong Ye
2015-01-01
Several previous studies have used the Cellular Automaton (CA) for the modeling of bicycle traffic flow. However, previous CA models have several limitations, resulting in differences between the simulated and the observed traffic flow features. The primary objective of this study is to propose a modified CA model for simulating the characteristics of mixed bicycle traffic flow. Field data were collected on physically separated bicycle path in Shanghai, China, and were used to calibrate the C...
Modeling of solidification grain structure for Ti-45%Al alloy ingot by cellular automaton
Institute of Scientific and Technical Information of China (English)
WU Shi-ping; LIU Dong-rong; GUO Jing-jie; FU Heng-zhi
2005-01-01
A cellular automaton model for simulating grain structure formation during solidification processes of Ti45%Al(mole fraction) alloy ingot was developed, based on finite differential method for macroscopic modeling of heat transfer and a cellular automaton technique for microscopic modeling of nucleation, growth, solute redistribution and solute diffusion. The relation between the growth velocity of a dendrite tip and the local undercooling,which consists of constitutional, thermal, curvature and attachment kinetics undercooling is calculated according to the Kurz-Giovanola-Trivedi model. The effect of solidification contraction is taken into consideration. The influence of process variables upon the resultant grain structures was investigated. Special moving allocation technique was designed to minimize the computation time and memory size associated with a large number of cells. The predicted grain structures are in good agreement with the experimental results.
An Extended Cellular Automaton Model for Train Traffic Flow on the Dedicated Passenger Lines
Directory of Open Access Journals (Sweden)
Wenbo Zhao
2014-01-01
Full Text Available As one of the key components for the railway transportation system, the Train Operation Diagram can be greatly influenced by many extrinsic and intrinsic factors. Therefore, the railway train flow has shown the strong nonlinear characteristics, which makes it quite difficult to take further relative studies. Fortunately, the cellular automaton model has its own advantages in solving nonlinear problems and traffic flow simulation. Considering the mixed features of multispeed running trains on the passenger dedicated lines, this paper presents a new train model under the moving block system with different types of trains running with the cellular automaton idea. By analyzing such key factors as the maintenance skylight, the proportion of the multispeed running trains, and the distance between adjacent stations and departure intervals, the corresponding running rules for the cellular automaton model are reestablished herewith. By means of this CA model, the program of train running system is designed to analyze the potential impact on railway carrying capacity by various factors; the model can also be implemented to simulate the actual train running process and to draw the train operation diagram by computers. Basically the theory can be applied to organize the train operation on the dedicated passenger lines.
Infinity computations in cellular automaton forest-fire model
Iudin, D. I.; Sergeyev, Ya. D.; Hayakawa, M.
2015-03-01
Recently a number of traditional models related to the percolation theory has been considered by means of a new computational methodology that does not use Cantor's ideas and describes infinite and infinitesimal numbers in accordance with the principle 'The whole is greater than the part' (Euclid's Common Notion 5). Here we apply the new arithmetic to a cellular automaton forest-fire model which is connected with the percolation methodology and in some sense combines the dynamic and the static percolation problems and under certain conditions exhibits critical fluctuations. It is well known that there exist two versions of the model: real forest-fire model where fire catches adjacent trees in the forest in the step by step manner and simplified version with instantaneous combustion. Using new approach we observe that in both situations we deal with the same model but with different time resolution. We show that depending on the "microscope" we use the same cellular automaton forest-fire model reveals either instantaneous forest combustion or step by step firing. By means of the new approach it was also observed that as far as we choose an infinitesimal tree growing rate and infinitesimal ratio between the ignition probability and the growth probability we determine the measure or extent of the system size infinity that provides the criticality of the system dynamics. Correspondent inequalities for grosspowers are derived.
Motor Schema-Based Cellular Automaton Model for Pedestrian Dynamics
Weng, Wenguo; Hasemi, Yuji; Fan, Weicheng
A new cellular automaton model for pedestrian dynamics based on motor schema is presented. Each pedestrian is treated as an intelligent mobile robot, and motor schemas including move-to-goal, avoid-away and avoid-around drive pedestrians to interact with their environment. We investigate the phenomenon of many pedestrians with different move velocities escaping from a room. The results show that the pedestrian with high velocity have predominance in competitive evacuation, if we only consider repulsion from or avoiding around other pedestrians, and interaction with each other leads to disordered evacuation, i.e., decreased evacuation efficiency. Extensions of the model using learning algorithms for controlling pedestrians, i.e., reinforcement learning, neural network and genetic algorithms, etc. are noted.
Bialecki, Mariusz
2010-01-01
Inspired by extremely simplified view of the earthquakes we propose the stochastic domino cellular automaton model exhibiting avalanches. From elementary combinatorial arguments we derive a set of nonlinear equations describing the automaton. Exact relations between the average parameters of the model are presented. Depending on imposed triggering, the model reproduces both exponential and inverse power statistics of clusters.
Driver’s Awareness and Lane Changing Maneuver in Traffic Flow based on Cellular Automaton Model
Kohei Arai; Steven Ray Sentinuwo
2015-01-01
Effect of driver’s awareness (e.g., to estimate the speed and arrival time of another vehicle) on the lane changing maneuver is discussed. “Scope awareness” is defined as the visibility which is required for the driver to make a visual perception about road condition and the speed of vehicle that appears in the target lane for lane changing in the road. Cellular automaton based simulation model is created and applied to simulation studies for driver awareness behavior. This study clarifies re...
CATALAN NUMBERS, DYCK LANGUAGE AND TIME SERIES OF ELEMENTARY CELLULAR AUTOMATON OF RULE 56
Institute of Scientific and Technical Information of China (English)
QIN Dakang; XIE Huimin
2005-01-01
A new approach to study the evolution complexity of cellular automata is proposed and explained thoroughly by an example of elementary cellular automaton of rule 56. Using the tools of distinct excluded blocks, computational search and symbolic dynamics, the mathematical structure underlying the time series generated from the elementary cellular automaton of rule 56 is analyzed and its complexity is determined, in which the Dyck language and Catalan numbers emerge naturally.
Bit-Vectorized GPU Implementation of a Stochastic Cellular Automaton Model for Surface Growth
Kelling, Jeffrey; Gemming, Sibylle
2016-01-01
Stochastic surface growth models aid in studying properties of universality classes like the Kardar--Paris--Zhang class. High precision results obtained from large scale computational studies can be transferred to many physical systems. Many properties, such as roughening and some two-time functions can be studied using stochastic cellular automaton (SCA) variants of stochastic models. Here we present a highly efficient SCA implementation of a surface growth model capable of simulating billions of lattice sites on a single GPU. We also provide insight into cases requiring arbitrary random probabilities which are not accessible through bit-vectorization.
The cellular automaton track finder at high track multiplicities
Energy Technology Data Exchange (ETDEWEB)
Akishina, Valentina; Zyzak, Maksym [Goethe Univ. Frankfurt am Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany); JINR Joint Institute for Nuclear Research, Dubna (Russian Federation); Kisel, Ivan; Kulakov, Igor [Goethe Univ. Frankfurt am Main (Germany); Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, Darmstadt (Germany)
2013-07-01
The CBM experiment at FAIR is being designed to study heavy-ion collisions at extremely high interaction rates. The event selection has to be done online, therefore fast and efficient reconstruction algorithms are required. The Cellular Automaton (CA) track finder is fast and robust and thereby is used both for the online and offline track reconstruction in CBM. Since the CBM beam will have no bunch structure, but continuous, the reconstruction of time slices rather than events is needed. Measurements in this case will be 4D (x,y,z,t). In order to study the worst case scenario with no time measurment taken into account a number of minimum bias events (up to 100) was grouped into one, which was treated by the track finder as one event. The study has showed that CA track finder is stable with respect to track multiplicity: the efficiency of the algorithm decreases only by 4% for 100 minimum bias events in one group. The speed of the algorithm behaves as a second order polynomial with the number of track.
An implementation of cellular automaton model for single-line train working diagram
Institute of Scientific and Technical Information of China (English)
Hua Wei; Liu Jun
2006-01-01
According to the railway transportation system's characteristics,a new cellular automaton model for the singleline railway system is presented in this paper.Based on this model,several simulations were done to imitate the train operation under three working diagrams.From a different angle the results show how the organization of train operation impacts on the railway carrying capacity.By using the non-parallel train working diagram the influence of fast-train on slow-train is found to be the strongest.Many slow-trains have to wait in-between neighbouring stations to let the fast-train(s) pass through first.So the slow-train will advance like a wave propagating from the departure station to the arrival station.This also resembles the situation of a highway jammed traffic flow.Furthermore,the nonuniformity of travel times between the sections also greatly limits the railway carrying capacity.After converting the nonuniform sections into the sections with uniform travel times while the total travel time is kept unchanged,all three carrying capacities are improved greatly as shown by simulation.It also shows that the cellular automaton model is an effective and feasible way to investigate the railway transDortation system.
Yao Xiao; Jing Shi
2015-01-01
This paper aimed to analyze the influence of drivers’ behavior of phone use while driving on traffic flow, including both traffic efficiency and traffic safety. An improved cellular automaton model was proposed to simulate traffic flow with distracted drivers based on the Nagel-Schreckenberg model. The driving characters of drivers using a phone were first discussed and a value representing the probability to use a phone while driving was put into the CA model. Simulation results showed that ...
Mobile Robot Motion Using Cellular Automaton Model to Avoid Transient Obstacles
Directory of Open Access Journals (Sweden)
Kohei Arai
2013-10-01
Full Text Available The obstacle avoidance is currently treated by methods that fall into two broad categories: global and local approach. This paper considers the obstacles whose velocity and direction cannot be easily predicted. Such obstacle is called transient obstacle. To avoid such kind of obstacle, we introduce a local path planning method for a robotics by using cellular automaton approach. The cellular automaton was combined with Dijkstra shortest path algorithm as global path planning to obtain a path for mobile robot to be able to avoid transient obstacle along the path. Using the proposed method, a scene in a typical corridor has been created. Moreover, this paper also evaluated two kinds of obstacle avoidance motion. First, the robot uses the “stop and go” method, which is the robot decreases its speed while encounter a transient obstacle. The second one is detour method, in which the robot makes a detour motion to avoid a transient obstacle. To coupe the drawbacks of local path planning, this paper also propose the enhancement of detour method. The simulation results show that in dynamic environment with transient obstacles, the “stop and go” method produces minimal collision with shortest-distance path. While, using the detour method generates minimal collision with time-minimal navigation path.
Institute of Scientific and Technical Information of China (English)
ZHU Ming-fang; CAO Wei-sheng; CHEN Shuang-lin; XIE Fan-you; HONG Chunpyo; CHANG Y. Austin
2006-01-01
A modified cellular automaton (MCA) model has been extended to the ternary alloy system by coupling thermodynamic and phase equilibrium calculation engine PanEngine. In the present model the dendrite growth is driven by the difference between the local equilibrium liquidus temperature and local actual temperature, incorporating the effect of curvature. The local equilibrium liquidus temperature is calculated with PanEngine according to the local liquid concentrations of two solutes, which are determined by numerically solving the species transport equation in the domain. Model validation was carried out through the comparison of the simulated values to the prediction of the Scheil model for solute profiles in the primary dendrites. The simulated data with zero solid diffusivity and limited liquid diffusivity were increasingly close to the Scheil profiles as the solidification rate decreased. The simulated microstructure and microsegregation in an Al-Cu-Mg ternary alloy were compared with those obtained experimentally.
Driver’s Awareness and Lane Changing Maneuver in Traffic Flow based on Cellular Automaton Model
Directory of Open Access Journals (Sweden)
Kohei Arai
2015-08-01
Full Text Available Effect of driver’s awareness (e.g., to estimate the speed and arrival time of another vehicle on the lane changing maneuver is discussed. “Scope awareness” is defined as the visibility which is required for the driver to make a visual perception about road condition and the speed of vehicle that appears in the target lane for lane changing in the road. Cellular automaton based simulation model is created and applied to simulation studies for driver awareness behavior. This study clarifies relations between the lane changing behavior and the scope awareness parameter that reflects driver behavior. Simulation results show that the proposed model is valid for investigation of the important features of lane changing maneuver.
Institute of Scientific and Technical Information of China (English)
何红弟; 董力耘; 戴世强
2006-01-01
Traffic flows controlled by traffic light strategies were investigated via a cellular automaton model with anticipation, which is suitable for describing urban traffic. Three kinds of strategies, i.e., synchronized, green-wave and random switching lights, were designed, simulated and compared with each other. It is shown that the green-wave strategy is only valid at lower density and there is not an effective way with the three strategies to improve the efficiency of traffic flow at high density.
Jiao, Yang
2011-01-01
Understanding tumor invasion and metastasis is of crucial importance for both fundamental cancer research and clinical practice. In vitro experiments have established that the invasive growth of malignant tumors is characterized by the dendritic invasive branches composed of chains of tumor cells emanating from the primary tumor mass. The preponderance of previous tumor simulations focused on non-invasive (or proliferative) growth. The formation of the invasive cell chains and their interactions with the primary tumor mass and host microenvironment are not well understood. Here, we present a novel cellular automaton (CA) model that enables one to efficiently simulate invasive tumor growth in a heterogeneous host microenvironment. By taking into account a variety of microscopic-scale tumor-host interactions, including the short-range mechanical interactions between tumor cells and tumor stroma, degradation of extracellular matrix by the invasive cells and oxygen/nutrient gradient driven cell motions, our CA mo...
Micro-macroscopic coupling in the cellular automaton model of solidification
Directory of Open Access Journals (Sweden)
Vinicius Bertolazzi Biscuola
2010-12-01
Full Text Available A cellular automaton (CA model to predict the formation of grain macrostructure during solidification has been implemented and the coupling between the microscopic and the macroscopic submodels has been investigated. The microscopic submodel simulates the nucleation and growth of grains, whereas the macroscopic solves the heat conduction equation. The directional solidification of an Al-7 wt. (% Si alloy was simulated, enabling the calculation of the temperature and solid fraction profiles. The calculated temperature was used to obtain the solid fraction profile by an application of Scheil equation. This solid fraction disagrees with that calculated in the micro-macro coupling of the model, although this coupling is completely based on Scheil equation. Careful examination of the discrepancies shows that it is a result of the undercoolings for nucleation and growth of grains and also of the interpolations of enthalpy change and temperature from the finite volume mesh to the CA cell mesh.
Steady state speed distribution analysis for a combined cellular automaton traffic model
Institute of Scientific and Technical Information of China (English)
Wang Jun-Feng; Chen Gui-Sheng; Liu Jin
2008-01-01
Cellular Automaton (CA) baaed traffic flow models have been extensively studied due to their effectiveness and simplicity in recent years. This paper develops a discrete time Markov chain (DTMC) analytical framework for a Nagel-Schreckenberg and Fukui-Ishibashi combined CA model (W2H traffic flow model) from microscopic point of view to capture the macroscopic steady state speed distributions. The inter-vehicle spacing Markov chain and the steady state speed Markov chain are proved to be irreducible and ergodie. The theoretical speed probability distributions depending on the traffic density and stochastic delay probability are in good accordance with numerical simulations. The derived fundamental diagram of the average speed from theoretical speed distributions is equivalent to the results in the previous work.
A traffic flow cellular automaton model to considering drivers' learning and forgetting behaviour
Institute of Scientific and Technical Information of China (English)
Ding Jian-Xun; Huang Hai-Jun; Tian Qiong
2011-01-01
It is known that the commonly used NaSch cellular automaton (CA) model and its modifications can help explain the internal causes of the macro phenomena of traffic flow. However, the randomization probability of vehicle velocity used in these models is assumed to be an exogenous constant or a conditional constant, which cannot reflect the learning and forgetting behaviour of drivers with historical experiences. This paper further modifies the NaSch model by enabling the randomization probability to be adjusted on the bases of drivers' memory. The Markov properties of this modified model are discussed. Analytical and simulation results show that the traffic fundamental diagrams can be indeed improved when considering drivers' intelligent behaviour. Some new features of traffic are revealed by differently combining the model parameters representing learning and forgetting behaviour.
An improved cellular automaton model considering the effect of traffic lights and driving behaviour
He, Hong-Di; Lu, Wei-Zhen; Dong, Li-Yun
2011-04-01
This paper proposes an improved cellular automaton model to describe the urban traffic flow with the consideration of traffic light and driving behaviour effects. Based on the model, the characteristics of the urban traffic flow on a single-lane road are investigated under three different control strategies, i.e., the synchronized, the green wave and the random strategies. The fundamental diagrams and time-space patterns of the traffic flows are provided for these strategies respectively. It finds that the dynamical transition to the congested flow appears when the vehicle density is higher than a critical level. The saturated flow is less dependent on the cycle time and the strategies of the traffic light control, while the critical vehicle density varies with the cycle time and the strategies. Simulated results indicate that the green wave strategy is proven to be the most effective one among the above three control strategies.
CATS: a cellular automaton for tracking in silicon for the HERA-B vertex detector
International Nuclear Information System (INIS)
The new track reconstruction program CATS developed for the Vertex Detector System of the HERA-B experiment at DESY is presented. It employs a cellular automaton for track searching and the Kalman filter for track fitting. This results in a very fast algorithm that combines highly efficient track recognition with accurate and reliable track parameter estimation. To reduce the computational cost of the fit an optimized numerical implementation of the Kalman filter is used. Alternative approaches to the track reconstruction in the VDS are also discussed. Since 1999, after extensive tests on simulated data, CATS has been employed to reconstruct experimental data collected in HERA-B. Results regarding tracking performance, the accuracy of track parameter estimates and CPU time consumption are presented
CATS a cellular automaton for tracking in silicon for the HERA-B vertex detector
Abt, I; Kisel, I; Masciocchi, S
2002-01-01
The new track reconstruction program CATS developed for the Vertex Detector System of the HERA-B experiment at DESY is presented. It employs a cellular automaton for track searching and the Kalman filter for track fitting. This results in a very fast algorithm that combines highly efficient track recognition with accurate and reliable track parameter estimation. To reduce the computational cost of the fit an optimized numerical implementation of the Kalman filter is used. Alternative approaches to the track reconstruction in the VDS are also discussed. Since 1999, after extensive tests on simulated data, CATS has been employed to reconstruct experimental data collected in HERA-B. Results regarding tracking performance, the accuracy of track parameter estimates and CPU time consumption are presented.
An improved cellular automaton model considering the effect of traffic lights and driving behaviour
Institute of Scientific and Technical Information of China (English)
He Hong-Di; Lu Wei-Zhen; Dong Li-Yun
2011-01-01
This paper proposes an improved cellular automaton model to describe the urban traffic flow with the consideration of traffic light and driving behaviour effects. Based on the model, the characteristics of the urban traffic flow on a singlelane road are investigated under three different control strategies, i.e., the synchronized, the green wave and the random strategies. The fundamental diagrams and time-space patterns of the traffic flows are provided for these strategies respectively. It finds that the dynamical transition to the congested flow appears when the vehicle density is higher than a critical level. The saturated flow is less dependent on the cycle time and the strategies of the traffic light control,while the critical vehicle density varies with the cycle time and the strategies. Simulated results indicate that the green wave strategy is proven to be the most effective one among the above three control strategies.
A Modified Cellular Automaton Approach for Mixed Bicycle Traffic Flow Modeling
Directory of Open Access Journals (Sweden)
Xiaonian Shan
2015-01-01
Full Text Available Several previous studies have used the Cellular Automaton (CA for the modeling of bicycle traffic flow. However, previous CA models have several limitations, resulting in differences between the simulated and the observed traffic flow features. The primary objective of this study is to propose a modified CA model for simulating the characteristics of mixed bicycle traffic flow. Field data were collected on physically separated bicycle path in Shanghai, China, and were used to calibrate the CA model using the genetic algorithm. Traffic flow features between simulations of several CA models and field observations were compared. The results showed that our modified CA model produced more accurate simulation for the fundamental diagram and the passing events in mixed bicycle traffic flow. Based on our model, the bicycle traffic flow features, including the fundamental diagram, the number of passing events, and the number of lane changes, were analyzed. We also analyzed the traffic flow features with different traffic densities, traffic components on different travel lanes. Results of the study can provide important information for understanding and simulating the operations of mixed bicycle traffic flow.
Swallowing a cellular automaton pill: predicting drug release from a matrix tablet
Buchla, Ezra; Najera, Aisha; Radunskaya, Ami
2012-01-01
Matrix tablets are drug delivery devices designed to release a drug in a controlled manner over an extended period of time. We develop a cellular automaton (CA) model for the dissolution and release of a water-soluble drug and excipient from a matrix tablet of water-insoluble polymer. Cells of the CA are occupied by drug, excipient, water or polymer and the CA updating rules simulate the dissolution of drug and excipient and the subsequent diffusion of the dissolved substances. In addition we simulate the possible fracture of brittle drug and excipient powders during the tablet compression and the melting of the polymer during a possible thermal curing process. Different stirring mechanisms that facilitate the transport of dissolved drug in the fluid in which the tablet is immersed are modeled in the water cells adjacent to the boundary of the tablet. We find that our simulations can reproduce experimental drug release profiles. Our simulation tool can be used to streamline the formulation and production of s...
Mendonça, J. Ricardo G.
2016-07-01
We investigate the inactive-active phase transition in an array of additive (exclusive-or) cellular automata (CA) under noise. The model is closely related with the Domany-Kinzel (DK) probabilistic cellular automaton (PCA), for which there are rigorous as well as numerical estimates on the transition probabilities. Here, we characterize the critical behavior of the noisy additive cellular automaton by mean field analysis and finite-size scaling and show that its phase transition belongs to the directed percolation universality class of critical behavior. As a by-product of our analysis, we argue that the critical behavior of the noisy elementary CA 90 and 102 (in Wolfram’s enumeration scheme) must be the same. We also perform an empirical investigation of the mean field equations to assess their quality and find that away from the critical point (but not necessarily very far away) the mean field approximations provide a reasonably good description of the dynamics of the PCA.
Cellular Automaton Model for Simulating Station-front Turning-back%基于元胞自动机的列车站前折返仿真模型
Institute of Scientific and Technical Information of China (English)
徐瑞华; 石俊刚
2011-01-01
With an accurate description of urban rail transit station-front turning-back process, this paper establishes two cellular automaton models for two typical station-front turning-back modes,there are station-front single-line turning-back mode and station-front double-line turning-back mode. In order to simulate train turning-back accurately, the models set cell updated rules for different rail parts, besides that line identification .direction identification and signal identification are formulated to solve several problems,such as lane changing,steering and paths confliction preventing. Using computer programming to simulate the trainoperation process with the models proposed, analyzing speed-location and time-location diagrams of train operating,we find that the simulation results are exactly the same as the actual train turn-back processes,at the same time comparing the results of turning-back capacity worked out by simulating methods with the traditional graphic method,the error is only 2.4% ,it shows that the simulating models proposed can accurately simulate train turning-back operating process,it can be applied to train turning-back simulation.%在对城市轨道交通中列车站前折返过程准确描述的基础上,建立了2种典型站前折返模式的元胞自动机模型,即站前单渡线折返仿真模型和站前双渡线折返仿真模型.为准确模拟列车的折返过程,模型设定了列车在不同轨道部分的元胞更新规则,在此基础上还添加了线路标识、方向标识和信号标识等来实现列车的换道、转向和防止进路冲突等问题.采用计算机编程,运用已建立的模型来模拟列车的运行过程,对列车运行过程的速度-位置图和时间-位置图的分析发现,模型的模拟结果与实际列车的折返过程完全相同,同时采用仿真方法计算的折返站折返能力与传统图解法计算的结果误差仅为2.4％,由此说明所建立的模型能够准确模拟实际列
Cellular automaton model of crowd evacuation inspired by slime mould
Kalogeiton, V. S.; Papadopoulos, D. P.; Georgilas, I. P.; Sirakoulis, G. Ch.; Adamatzky, A. I.
2015-04-01
In all the living organisms, the self-preservation behaviour is almost universal. Even the most simple of living organisms, like slime mould, is typically under intense selective pressure to evolve a response to ensure their evolution and safety in the best possible way. On the other hand, evacuation of a place can be easily characterized as one of the most stressful situations for the individuals taking part on it. Taking inspiration from the slime mould behaviour, we are introducing a computational bio-inspired model crowd evacuation model. Cellular Automata (CA) were selected as a fully parallel advanced computation tool able to mimic the Physarum's behaviour. In particular, the proposed CA model takes into account while mimicking the Physarum foraging process, the food diffusion, the organism's growth, the creation of tubes for each organism, the selection of optimum tube for each human in correspondence to the crowd evacuation under study and finally, the movement of all humans at each time step towards near exit. To test the model's efficiency and robustness, several simulation scenarios were proposed both in virtual and real-life indoor environments (namely, the first floor of office building B of the Department of Electrical and Computer Engineering of Democritus University of Thrace). The proposed model is further evaluated in a purely quantitative way by comparing the simulation results with the corresponding ones from the bibliography taken by real data. The examined fundamental diagrams of velocity-density and flow-density are found in full agreement with many of the already published corresponding results proving the adequacy, the fitness and the resulting dynamics of the model. Finally, several real Physarum experiments were conducted in an archetype of the aforementioned real-life environment proving at last that the proposed model succeeded in reproducing sufficiently the Physarum's recorded behaviour derived from observation of the aforementioned
A self-modifying cellular automaton model of historical urbanization in the San Francisco Bay area
Clarke, K.C.; Hoppen, S.; Gaydos, L.
1997-01-01
In this paper we describe a cellular automaton (CA) simulation model developed to predict urban growth as part of a project for estimating the regional and broader impact of urbanization on the San Francisco Bay area's climate. The rules of the model are more complex than those of a typical CA and involve the use of multiple data sources, including topography, road networks, and existing settlement distributions, and their modification over time. In addition, the control parameters of the model are allowed to self-modify: that is, the CA adapts itself to the circumstances it generates, in particular, during periods of rapid growth or stagnation. In addition, the model was written to allow the accumulation of probabilistic estimates based on Monte Carlo methods. Calibration of the model has been accomplished by the use of historical maps to compare model predictions of urbanization, based solely upon the distribution in year 1900, with observed data for years 1940, 1954, 1962, 1974, and 1990. The complexity of this model has made calibration a particularly demanding step. Lessons learned about the methods, measures, and strategies developed to calibrate the model may be of use in other environmental modeling contexts. With the calibration complete, the model is being used to generate a set of future scenarios for the San Francisco Bay area along with their probabilities based on the Monte Carlo version of the model. Animated dynamic mapping of the simulations will be used to allow visualization of the impact of future urban growth.
Large-scale parallel lattice Boltzmann-cellular automaton model of two-dimensional dendritic growth
Jelinek, Bohumir; Eshraghi, Mohsen; Felicelli, Sergio; Peters, John F.
2014-03-01
An extremely scalable lattice Boltzmann (LB)-cellular automaton (CA) model for simulations of two-dimensional (2D) dendritic solidification under forced convection is presented. The model incorporates effects of phase change, solute diffusion, melt convection, and heat transport. The LB model represents the diffusion, convection, and heat transfer phenomena. The dendrite growth is driven by a difference between actual and equilibrium liquid composition at the solid-liquid interface. The CA technique is deployed to track the new interface cells. The computer program was parallelized using the Message Passing Interface (MPI) technique. Parallel scaling of the algorithm was studied and major scalability bottlenecks were identified. Efficiency loss attributable to the high memory bandwidth requirement of the algorithm was observed when using multiple cores per processor. Parallel writing of the output variables of interest was implemented in the binary Hierarchical Data Format 5 (HDF5) to improve the output performance, and to simplify visualization. Calculations were carried out in single precision arithmetic without significant loss in accuracy, resulting in 50% reduction of memory and computational time requirements. The presented solidification model shows a very good scalability up to centimeter size domains, including more than ten million of dendrites. Catalogue identifier: AEQZ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEQZ_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, UK Licensing provisions: Standard CPC license, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 29,767 No. of bytes in distributed program, including test data, etc.: 3131,367 Distribution format: tar.gz Programming language: Fortran 90. Computer: Linux PC and clusters. Operating system: Linux. Has the code been vectorized or parallelized?: Yes. Program is parallelized using MPI
Institute of Scientific and Technical Information of China (English)
LI Jun-chao; XIE Zhi-yuan; LI Song-pu; ZANG Yan-yan
2016-01-01
The dynamic recrystallization (DRX) process of hot compressed aluminium alloy 7050 was predicted using cellular automaton (CA) combined with topology deformation. The hot deformatation characteristics of aluminium alloy 7050 were investigated by hot uniaxial compression tests in order to obtain the material parameters used in the CA model. The influences of process parameters (strain, strain rate and temperature) on the fraction of DRX and the average recrystallization grain (R-grain) size were investigated and discussed. It is found that larger stain, higher temperature and lower strain rate (less than 0.1 s–1) are beneficial to the increasing fraction of DRX. And the deformation temperature affects the mean R-grain size much more greatly than other parameters. It is also noted that there is a critical strain for the occurrence of DRX which is related to strain rate and temperature. In addition, it is shown that the CA model with topology deformation is able to simulate the microstructural evolution and the flow behavior of aluminium alloy 7050 material under various deformation conditions.
Cellular automaton models for traffic flow considering opposite driving of an emergency vehicle
Zhao, Han-Tao; Li, Jing-Ru; Nie, Cen
2015-12-01
Aiming at two-lane road, this paper establishes three models to analyze the opposite-overtaking rules of emergency vehicle based on cellular automaton (CCA) model. Based on the simulation of mixed traffic flow for multi-density conditions, the density-speed diagrams have been obtained consequently. According to the analysis, when the traffic density of the opposite lane is low, the opposite driving behavior of emergency vehicle can improve the average speed effectively. At the same time, if the cocurrent lane is in high-density traffic, the traffic in the opposite lane will be disturbed, but the vehicles in the cocurrent lane will not be affected. The paper has further discussed the influence of different emergency vehicle driving behaviors on traffic. The results reveal that as the traffic of the opposite lane is in a low-density range, if emergency vehicle operates overtaking behavior precisely, the greater the density of the cocurrent lane is, the more obviously the speed improve. Meanwhile large random fluctuation of overtaking times will occur. While the risky lane change behavior displays different traffic characteristics, that is when the same direction lane is in high density, the speed increases slightly and the lane change number is changed regularly.
2D photonic crystal complete band gap search using a cyclic cellular automaton refination
González-García, R.; Castañón, G.; Hernández-Figueroa, H. E.
2014-11-01
We present a refination method based on a cyclic cellular automaton (CCA) that simulates a crystallization-like process, aided with a heuristic evolutionary method called differential evolution (DE) used to perform an ordered search of full photonic band gaps (FPBGs) in a 2D photonic crystal (PC). The solution is proposed as a combinatorial optimization of the elements in a binary array. These elements represent the existence or absence of a dielectric material surrounded by air, thus representing a general geometry whose search space is defined by the number of elements in such array. A block-iterative frequency-domain method was used to compute the FPBGs on a PC, when present. DE has proved to be useful in combinatorial problems and we also present an implementation feature that takes advantage of the periodic nature of PCs to enhance the convergence of this algorithm. Finally, we used this methodology to find a PC structure with a 19% bandgap-to-midgap ratio without requiring previous information of suboptimal configurations and we made a statistical study of how it is affected by disorder in the borders of the structure compared with a previous work that uses a genetic algorithm.
Cellular Automaton Model for Immunology of Tumor Growth
Voitikova, M
1998-01-01
The stochastic discrete space-time model of an immune response on tumor spreading in a two-dimensional square lattice has been developed. The immunity-tumor interactions are described at the cellular level and then transferred into the setting of cellular automata (CA). The multistate CA model for system, in which all statesoflattice sites, composing of both immune and tumor cells populations, are the functions of the states of the 12 nearest neighbors. The CA model incorporates the essential featuresof the immunity-tumor system. Three regimes of neoplastic evolution including metastatic tumor growth and screen effect by inactive immune cells surrounding a tumor have been predicted.
Modeling of aluminum-silicon irregular eutectic growth by cellular automaton model
Directory of Open Access Journals (Sweden)
Rui Chen
2016-03-01
Full Text Available Due to the extensive application of Al-Si alloys in the automotive and aerospace industries as structural components, an understanding of their microstructural formation, such as dendrite and (Al+Si eutectic, is of great importance to control the desirable microstructure, so as to modify the performance of castings. Since previous major themes of microstructural simulation are dendrite and regular eutectic growth, few efforts have been paid to simulate the irregular eutectic growth. Therefore, a multiphase cellular automaton (CA model is developed and applied to simulate the time-dependent Al-Si irregular eutectic growth. Prior to model establishment, related experiments were carried out to investigate the influence of cooling rate and Sr modification on the growth of eutectic Si. This CA model incorporates several aspects, including growth algorithms and nucleation criterion, to achieve the competitive and cooperative growth mechanism for nonfaceted-faceted Al-Si irregular eutectic. The growth kinetics considers thermal undercooling, constitutional undercooling, and curvature undercooling, as well as the anisotropic characteristic of eutectic Si growth. The capturing rule takes into account the effects of modification on the silicon growth behaviors. The simulated results indicate that for unmodified alloy, the higher eutectic undercooling results in the higher eutectic growth velocity, and a more refined eutectic microstructure as well as narrower eutectic lamellar spacing. For modified alloy, the eutectic silicon tends to be obvious fibrous morphology and the morphology of eutectic Si is determined by both chemical modifier and cooling rate. The predicted microstructure of Al-7Si alloy under different solidification conditions shows that this proposed model can successfully reproduce both dendrite and eutectic microstructures.
Knowledge Discovery in Database: Induction Graph and Cellular Automaton
Baghdad Atmani; Bouziane Beldjilali
2012-01-01
In this article we present the general architecture of a cellular machine, which makes it possible to reduce the size of induction graphs, and to optimize automatically the generation of symbolic rules. Our objective is to propose a tool for detecting and eliminating non relevant variables from the database. The goal, after acquisition by machine learning from a set of data, is to reduce the complexity of storage, thus to decrease the computing time. The objective of this work is to experimen...
Theory of multicolor lattice gas - A cellular automaton Poisson solver
Chen, H.; Matthaeus, W. H.; Klein, L. W.
1990-01-01
The present class of models for cellular automata involving a quiescent hydrodynamic lattice gas with multiple-valued passive labels termed 'colors', the lattice collisions change individual particle colors while preserving net color. The rigorous proofs of the multicolor lattice gases' essential features are rendered more tractable by an equivalent subparticle representation in which the color is represented by underlying two-state 'spins'. Schemes for the introduction of Dirichlet and Neumann boundary conditions are described, and two illustrative numerical test cases are used to verify the theory. The lattice gas model is equivalent to a Poisson equation solution.
Directory of Open Access Journals (Sweden)
Yao Xiao
2015-01-01
Full Text Available This paper aimed to analyze the influence of drivers’ behavior of phone use while driving on traffic flow, including both traffic efficiency and traffic safety. An improved cellular automaton model was proposed to simulate traffic flow with distracted drivers based on the Nagel-Schreckenberg model. The driving characters of drivers using a phone were first discussed and a value representing the probability to use a phone while driving was put into the CA model. Simulation results showed that traffic flow rate was significantly reduced if some drivers used a phone compared to no phone use. The flow rate and velocity decreased as the proportion of drivers using a phone increased. While, under low density, the risk of traffic decreased first and then increased as the distracted drivers increased, the distracted behavior of drivers, like using a phone, could reduce the flow rate by 5 percent according to the simulation.
Modeling dynamics of HIV infected cells using stochastic cellular automaton
Precharattana, Monamorn; Triampo, Wannapong
2014-08-01
Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. Several cellular automata (CA) models have been introduced to gain insights into the dynamics of the disease progression but none of them has taken into account effects of certain immune cells such as the dendritic cells (DCs) and the CD8+ T lymphocytes (CD8+ T cells). In this work, we present a CA model, which incorporates effects of the HIV specific immune response focusing on the cell-mediated immunities, and investigate the interaction between the host immune response and the HIV infected cells in the lymph nodes. The aim of our work is to propose a model more realistic than the one in Precharattana et al. (2010) [10], by incorporating roles of the DCs, the CD4+ T cells, and the CD8+ T cells into the model so that it would reproduce the HIV infection dynamics during the primary phase of HIV infection.
A Cellular Automaton Model for Heterogeneous and Incosistent Driver Behavior in Urban Traffic
Institute of Scientific and Technical Information of China (English)
LIUMing-Zhe; ZHAO Shi-Bo; WANG Rui-Li
2012-01-01
In this paper a cellular automaton model is proposed to describe driver behavior at a single-lane urban roundabout. Driver behavior has been considered as heterogeneous and inconsistent. Most traffic papers in the literature just discussed heterogeneous driver behavior, to our best knowledge. Two truncated Caussian distributions are used to model heterogeneous and inconsistent driver behavior, respectively. The physical meanings of two truncated distributions are indicated. This method may help enhance a better understanding of driver behavior at roundabout traffic, and even possibly provide references for roundabout design and management.
A Cellular Automaton Model for Heterogeneous and Incosistent Driver Behavior in Urban Traffic
Liu, Ming-Zhe; Zhao, Shi-Bo; Wang, Rui-Li
2012-11-01
In this paper a cellular automaton model is proposed to describe driver behavior at a single-lane urban roundabout. Driver behavior has been considered as heterogeneous and inconsistent. Most traffic papers in the literature just discussed heterogeneous driver behavior, to our best knowledge. Two truncated Gaussian distributions are used to model heterogeneous and inconsistent driver behavior, respectively. The physical meanings of two truncated distributions are indicated. This method may help enhance a better understanding of driver behavior at roundabout traffic, and even possibly provide references for roundabout design and management.
Kerner, Boris S.; Klenov, Sergey L.; Hermanns, Gerhard; Schreckenberg, Michael
2013-09-01
Based on simulations with cellular automaton (CA) traffic flow models, a generic physical feature of the three-phase models studied in the paper is disclosed. The generic feature is a discontinuous character of driver over-acceleration caused by a combination of two qualitatively different mechanisms of over-acceleration: (i) Over-acceleration through lane changing to a faster lane, (ii) over-acceleration occurring in car-following without lane changing. Based on this generic feature a new three-phase CA traffic flow model is developed. This CA model explains the set of the fundamental empirical features of traffic breakdown in real heterogeneous traffic flow consisting of passenger vehicles and trucks. The model simulates also quantitative traffic pattern characteristics as measured in real heterogeneous flow.
Kizilirmak, Ganimet Mülazımoğlu
2015-12-01
The four-dimensional Ising model is simulated on the Creutz cellular automaton (CCA) near the infinite-lattice critical temperature for the lattice with the linear dimension 4 ⩽ L ⩽ 22. The temperature dependence of Binder parameter ( g L) are analyzed for the lattice with the linear dimension 4 ⩽ L ⩽ 22. In this study conducted highly detailed, two different types of behavior were determined as a result of varying linear lattice dimension. The infinite lattice critical temperatures are obtained to be T c = 6.6845 ± 0.0005 in interval 4 ⩽ L ⩽ 12 and T c = 6.6807 ± 0.0024 in interval 14 ⩽ L ⩽ 22. The finite and infinite lattice critical exponents for the order parameter, the magnetic susceptibility and the specific heat are computed from the results of simulations by using finite-size scaling relations. Critical linear lattice size have been identified as L = 14.
Traffic paradox on a road segment based on a cellular automaton: Impact of lane-changing behavior
Feng, Shumin; Li, Jinyang; Ding, Ning; Nie, Cen
2015-06-01
The traffic paradox "faster is slower" does not always apply. To study when and where it is valid, a simulation for a real road segment is performed using a novel cellular automaton. This simulation is used to analyze the change in global traffic flow status during free lane-changing behavior under general urban traffic conditions. The impact of lane-changing behavior is quantified into two aspects, time and space, and are described by average delay and transitable flow, respectively. Then surfaces are obtained, which adopt the arriving probability of vehicles and the green ratio as dual independent variables. Thus by the comparison of two surfaces, free lane-changing and straight proceeding, the horizontal projection of the intersecting lines is solved. Finally, the range of occurrence and reasons for the paradox are analyzed.
Institute of Scientific and Technical Information of China (English)
梁龙; 焦阳
2015-01-01
肿瘤的侵袭和转移行为，常常是导致病人的死亡的原因。而人们对这些由复杂的肿瘤-宿主以及肿瘤细胞与细胞之间相互作用而产生的群体性行为知之甚少。对这一过程了解的加深，需要多学科间的合作。在本篇文章中，作者将简要回顾肿瘤物理领域的一种新手段，即近年来由作者参与的通过元胞自动机(CA)模型来研究微环境促进的实体瘤侵袭性生长的研究，该模型整合了一系列微观的肿瘤宿主相互作用，包含了肿瘤细胞对细胞外基质的降解，肿瘤细胞趋向养分的迁移，肿瘤生长导致的局部组织压力累积以及该压力对局部的肿瘤-宿主界面稳定性的影响，并且，肿瘤生长时细胞间的粘连也被明确地考虑进来。该元胞自动机模型能成功地重现出一系列的标志性的肿瘤侵袭行为，这有力地表明出该模型的有效性和预测能力。这一模型，如果能与临床数据结合，理论上能够拓展从医学数据中得到的现有结论，帮助设计新的实验，检验假说，并且在实验难以检测到的情形下，预测肿瘤的行为，协助癌症的早期诊断和预后，并针对不同病人，提出最优的个体化医疗方案。%Emergence of invasive and metastatic behavior in malignant tumors can often lead to fatal outcomes for patients. The collective malignant tumor behavior resulting from the complex tumor-host interactions and the interactions between the tumor cells are currently poorly understood. Progress towards such an understanding necessarily requires an interdis-ciplinary and collaborative effort. In this paper, we review a state-of-art simulation technique, i.e., a cellular automaton (CA) model which has been developed by the authors over the past few years to investigate microenvironment-enhanced invasive growth of avascular solid tumors. This CA model incorporates a variety of microscopic-scale tumor-host in
An Option Pricing Model Based on Cellular Automaton%基于元胞自动机的期权定价模型
Institute of Scientific and Technical Information of China (English)
李捷
2011-01-01
Option pricing is one of the most difficult problems in financial research. The key to the problem is how to simulate the randomness of the underlying asset price. This paper designs and implements an option pricing model based on the cellular automaton, which treats market participants as the cells in the cellular automaton. The model uses cellular automaton rules to simulate the interactions between traders and the changes of underlying asset prices. The paper compares the output data of the model with the calculation results of the Black-Scholes model, tests the normality of the model＇s output data, and finds that the option pricing model based on the cellular automaton is not only feasible, but also more effective than the Black-Scholes model.%针对期权定价难于模拟基础资产价格波动随机性的问题，设计了基于元胞自动机的期权定价模型．该模型将市场参与者看作一个个的元胞，使用元胞规则来模拟金融市场中交易者之间的交互行为。从而在总体上模拟出基础资产价格的变化．比较了模型产出的数据和Black-Scholes模型的计算结果，检验了模型产出数据的正态性，发现基于元胞自动机的期权定价模型不仅具有可行性，而且比Black-Scholes模型更有效．
Reprint of Infinity computations in cellular automaton forest-fire model
Iudin, D. I.; Sergeyev, Ya. D.; Hayakawa, M.
2015-04-01
Recently a number of traditional models related to the percolation theory has been considered by means of a new computational methodology that does not use Cantor's ideas and describes infinite and infinitesimal numbers in accordance with the principle 'The whole is greater than the part' (Euclid's Common Notion 5). Here we apply the new arithmetic to a cellular automaton forest-fire model which is connected with the percolation methodology and in some sense combines the dynamic and the static percolation problems and under certain conditions exhibits critical fluctuations. It is well known that there exist two versions of the model: real forest-fire model where fire catches adjacent trees in the forest in the step by step manner and simplified version with instantaneous combustion. Using new approach we observe that in both situations we deal with the same model but with different time resolution. We show that depending on the "microscope" we use the same cellular automaton forest-fire model reveals either instantaneous forest combustion or step by step firing. By means of the new approach it was also observed that as far as we choose an infinitesimal tree growing rate and infinitesimal ratio between the ignition probability and the growth probability we determine the measure or extent of the system size infinity that provides the criticality of the system dynamics. Correspondent inequalities for grosspowers are derived.
Maerivoet, S; Immers, B; De Moor, B; Maerivoet, Sven; Logghe, Steven; Immers, Ben; Moor, Bart De
2005-01-01
In this paper, we describe a relation between a microscopic traffic cellular automaton (TCA) model (i.e., the stochastic TCA model of Nagel and Schreckenberg) and the macroscopic first-order hydrodynamic model of Lighthill, Whitham, and Richards (LWR). The innovative aspect of our approach, is that we explicitly derive the LWR's fundamental diagram directly from the STCA's rule set, by assuming a stationarity condition that converts the STCA's rules into a set of linear inequalities. In turn, these constraints define the shape of the fundamental diagram, which is then specified to the LWR model. Application of our methodology to a simulation case study, allows us to compare the tempo-spatial behavior of both models. Our results indicate that, in the presence of noise, the capacity flows in the derived fundamental diagram are overestimations of those of the STCA model. Directly specifying the STCA's capacity flows to the LWR fundamental diagram, effectively remedies most of the mismatches between both approach...
A Cellular Automaton Model for Tumor Dormancy: Emergence of a Proliferative Switch
Chen, Duyu; Torquato, Salvatore
2014-01-01
Malignant cancers that lead to fatal outcomes for patients may remain dormant for very long periods of time. Although individual mechanisms such as cellular dormancy, angiogenic dormancy and immunosurveillance have been proposed, a comprehensive understanding of cancer dormancy and the "switch" from a dormant to a proliferative state still needs to be strengthened from both a basic and clinical point of view. Computational modeling enables one to explore a variety of scenarios for possible but realistic microscopic dormancy mechanisms and their predicted outcomes. The aim of this paper is to devise such a predictive computational model of dormancy with an emergent "switch" behavior. Specifically, we generalize a previous cellular automaton (CA) model for proliferative growth of solid tumor that now incorporates a variety of cell-level tumor-host interactions and different mechanisms for tumor dormancy, for example the effects of the immune system. Our new CA rules induce a natural "competition" between the tu...
2D cellular automaton model for the evolution of active region coronal plasmas
Fuentes, Marcelo López
2016-01-01
We study a 2D cellular automaton (CA) model for the evolution of coronal loop plasmas. The model is based on the idea that coronal loops are made of elementary magnetic strands that are tangled and stressed by the displacement of their footpoints by photospheric motions. The magnetic stress accumulated between neighbor strands is released in sudden reconnection events or nanoflares that heat the plasma. We combine the CA model with the Enthalpy Based Thermal Evolution of Loops (EBTEL) model to compute the response of the plasma to the heating events. Using the known response of the XRT telescope on board Hinode we also obtain synthetic data. The model obeys easy to understand scaling laws relating the output (nanoflare energy, temperature, density, intensity) to the input parameters (field strength, strand length, critical misalignment angle). The nanoflares have a power-law distribution with a universal slope of -2.5, independent of the input parameters. The repetition frequency of nanoflares, expressed in t...
Transition between immune and disease states in a cellular automaton model of clonal immune response
Bezzi, M; Ruffo, S; Seiden, P E; Bezzi, Michele; Celada, Franco; Ruffo, Stefano; Seiden, Philip E.
1997-01-01
In this paper we extend the Celada-Seiden (CS) model of the humoral immune response to include infectious virus and cytotoxic T lymphocytes (cellular response). The response of the system to virus involves a competition between the ability of the virus to kill the host cells and the host's ability to eliminate the virus. We find two basins of attraction in the dynamics of this system, one is identified with disease and the other with the immune state. There is also an oscillating state that exists on the border of these two stable states. Fluctuations in the population of virus or antibody can end the oscillation and drive the system into one of the stable states. The introduction of mechanisms of cross-regulation between the two responses can bias the system towards one of them. We also study a mean field model, based on coupled maps, to investigate virus-like infections. This simple model reproduces the attractors for average populations observed in the cellular automaton. All the dynamical behavior connect...
Institute of Scientific and Technical Information of China (English)
张俊娜; 范海菊
2012-01-01
In this paper, a new approach is proposed to solve urgent evacuation in fire disaster by combining artificial potential field with cellular automata model. First, aiming at the evacuated individual in fire, a micro-model is established using potential field in which factors influencing human behavior are quantified. Second, several cellular-mobile rules are constructed based on ihe above model to describe the next step of walking path. Finally, the evacuation system is simulated by VC+ + developing environment to represent the entire dynamic process, and then collects the data about two cases: whether to open e-mergency exits and whether lo conduct personnel persuasion. Simulation results show this system can describe the evacuation process accurately, which can provide us with detailed guidance.%基于元胞自动机模型对公众场合火灾中人员疏散进行研究,通过对火灾中疏散个体微观建模,结合人工势场将影响人行为的火、门和障碍物等各种因素量化,构建出元胞的移动规则,从而确定元胞下一时间步长的移动路径.仿真结果显示,该系统能够较真实地模拟人员疏散过程.
ONE-DIMENSIONAL CELLULAR AUTOMATON MODEL OF TRAFFIC FLOW BASED ON CAR-FOLLOWING IDEA
Institute of Scientific and Technical Information of China (English)
董力耘; 薛郁; 戴世强
2002-01-01
An improved one-dimensional CA (Cellular Automaton) traffic model was proposed to describe the highway traffic under the periodic boundary conditions. This model was based on the idea of the car-following model, which claims that the motion of a vehicle at one time step depends on both its headway and the synchronous motion of the front vehicle,thus including indirectly the influence of its sub-neighboring vehicle. In addition, the socalled safety distance was introduced to consider the deceleration behavior of vehicles and the stochastic factor was taken into account by introducing the deceleration probability.Meanwhile, the conditional deceleration in the model gives a better description of the phenomena observed on highways. It is found that there exists the metastability and hysteresis effect of traffic flow in the neighborhood of critical density under different initial conditions.Since this model gives a reasonable depiction of the motion of a single vehicle, it is easy to be extended to the case of traffic flow under the control of traffic lights in cities.
Stable oscillations of a predator-prey probabilistic cellular automaton: a mean-field approach
Energy Technology Data Exchange (ETDEWEB)
Tome, Tania; Carvalho, Kelly C de [Instituto de FIsica, Universidade de Sao Paulo, Caixa Postal 66318, 05315-970 Sao Paulo (Brazil)
2007-10-26
We analyze a probabilistic cellular automaton describing the dynamics of coexistence of a predator-prey system. The individuals of each species are localized over the sites of a lattice and the local stochastic updating rules are inspired by the processes of the Lotka-Volterra model. Two levels of mean-field approximations are set up. The simple approximation is equivalent to an extended patch model, a simple metapopulation model with patches colonized by prey, patches colonized by predators and empty patches. This approximation is capable of describing the limited available space for species occupancy. The pair approximation is moreover able to describe two types of coexistence of prey and predators: one where population densities are constant in time and another displaying self-sustained time oscillations of the population densities. The oscillations are associated with limit cycles and arise through a Hopf bifurcation. They are stable against changes in the initial conditions and, in this sense, they differ from the Lotka-Volterra cycles which depend on initial conditions. In this respect, the present model is biologically more realistic than the Lotka-Volterra model.
CellLab-CTS 2015: continuous-time stochastic cellular automaton modeling using Landlab
Tucker, Gregory E.; Hobley, Daniel E. J.; Hutton, Eric; Gasparini, Nicole M.; Istanbulluoglu, Erkan; Adams, Jordan M.; Siddartha Nudurupati, Sai
2016-02-01
CellLab-CTS 2015 is a Python-language software library for creating two-dimensional, continuous-time stochastic (CTS) cellular automaton models. The model domain consists of a set of grid nodes, with each node assigned an integer state code that represents its condition or composition. Adjacent pairs of nodes may undergo transitions to different states, according to a user-defined average transition rate. A model is created by writing a Python code that defines the possible states, the transitions, and the rates of those transitions. The code instantiates, initializes, and runs one of four object classes that represent different types of CTS models. CellLab-CTS provides the option of using either square or hexagonal grid cells. The software provides the ability to treat particular grid-node states as moving particles, and to track their position over time. Grid nodes may also be assigned user-defined properties, which the user can update after each transition through the use of a callback function. As a component of the Landlab modeling framework, CellLab-CTS models take advantage of a suite of Landlab's tools and capabilities, such as support for standardized input and output.
A nanoflare based cellular automaton model and the observed properties of the coronal plasma
Fuentes, Marcelo López
2016-01-01
We use the cellular automaton model described in L\\'opez Fuentes \\& Klimchuk (2015, ApJ, 799, 128) to study the evolution of coronal loop plasmas. The model, based on the idea of a critical misalignment angle in tangled magnetic fields, produces nanoflares of varying frequency with respect to the plasma cooling time. We compare the results of the model with active region (AR) observations obtained with the Hinode/XRT and SDO/AIA instruments. The comparison is based on the statistical properties of synthetic and observed loop lightcurves. Our results show that the model reproduces the main observational characteristics of the evolution of the plasma in AR coronal loops. The typical intensity fluctuations have an amplitude of 10 to 15\\% both for the model and the observations. The sign of the skewness of the intensity distributions indicates the presence of cooling plasma in the loops. We also study the emission measure (EM) distribution predicted by the model and obtain slopes in log(EM) versus log(T) betw...
Institute of Scientific and Technical Information of China (English)
A.Yu. SMOLIN; E.V. SHILKO; S.V. ASTAFUROV; I.S. KONOVALENKO; S.P. BUYAKOVA; S.G. PSAKHIE
2015-01-01
Two classes of composite materials are considered: classical metaleceramic composites with reinforcing hard inclusions as well as hard ceramics matrix with soft gel inclusions. Movable cellular automaton method is used for modeling the mechanical behaviors of such different heterogeneous materials. The method is based on particle approach and may be considered as a kind of discrete element method. The main feature of the method is the use of many-body forces of inter-element interaction within the formalism of simply deformable element approximation. It was shown that the strength of reinforcing particles and the width of particle-binder interphase boundaries had determining influence on the service characteristics of metaleceramic composite. In particular, the increasing of strength of carbide inclusions may lead to significant increase in the strength and ultimate strain of composite material. On the example of porous zirconia ceramics it was shown that the change in the mechanical properties of pore surface leads to the corresponding change in effective elastic modulus and strength limit of the ceramic sample. The less is the pore size, the more is this effect. The increase in the elastic properties of pore surface of ceramics may reduce its fracture energy.
Directory of Open Access Journals (Sweden)
S. G. Psakhie
2013-04-01
Full Text Available An approach to multiscale description of deformation and fracture of brittle porous materials on the basis of movable cellular automaton method was proposed. The material characterized by pore size distribution function having two maxima was considered. The core of the proposed approach consists in finding the automaton effective response function by means of direct numerical simulation of representative volume of the porous material. A hierarchical two-scale model of mechanical behavior of ceramics under compression and shear loading was developed. Zirconia based ceramics with pore size greater than the average grain size was considered. At the first scale of the model only small pores (corresponding to the first maximum of the pore size distribution function were taking into account explicitly (by removing automata from the initial structure. The representative volume and effective elastic properties of the porous material at this scale were evaluated. At the second scale of the model, big pores were taking into account explicitly, the parameters of the matrix corresponded to the ones determined at the first scale. Simulation results showed that the proposed multiscale model allows qualitatively and quantitatively correct describing of deformation and fracture of brittle material with hierarchical porous structure.
Institute of Scientific and Technical Information of China (English)
张琴; 张友静; 张滔
2012-01-01
This paper presents an improved Case-Based Reasoning based Cellular Automata model (CBR-CA) in modeling multiple land covers changes. Currently, various research communities have tried to build and apply mathematic models with CBR or CA as systemic method to study concerning specific geo-scientific problems. However.original CBR-CA model has problems in modeling numerous class changes,especially in modeling land cover changes with large region and long time. In this paper,an improved CBR-CA is designed to calculate conversion probabilities for computing multiple land cover. Firstly, the macro transition probability of each class is added to the objective function, which can express the characteristic of multiple class changes. Then, considering the time weight, which can reflect the space-time changes of land cover, the final probability function is derived by both. In addition, due to variation of land cover types and their spatial relationships in complex geography changes, Monte Carlo is made use of deciding the final transition classes. This model has been applied to simulate the land cover changes of the source of the Yellow River in 1995,2000 and 2006,and has been applied to predict this region in 2012 and 2018 by building the historical case-based database with the land cover data in 1977 and 1985. The simulated and actual patterns are basic consistent in amounts,accounting for 0.002% ,0.012% and 0.005% of the total error,respectively, the space accuracies totally beyond 70%. The result indicates that this model can simulate and predict the land cover changes which are with multiple classes and with long time.%对基于案例推理的元胞自动机模型(CBR-CA)进行改进,将各类别的宏观转移概率添加到目标函数中,体现各类别的转变特征,并增加时间权重来确定转移概率,实现时间尺度上的模拟；由于土地覆盖变化的多样性和空间结构的复杂性,利用Monte Carlo(M-C)法确定土地覆盖的最终转换
Institute of Scientific and Technical Information of China (English)
Jiang Rui; Jin Wen-Long; Wu Qing-Song
2008-01-01
Recently, a number of efforts are underway to investigate inter-vehicle communications (IVC). This paper studies the instantaneous information propagation behaviours based on IVC in three different traffic situations (free flow,synchronized flow and stop-and-go waves) in a cellular automaton model. It is shown that different behaviours appear in stop-and-go waves from those in free flow and synchronized flow. While the distribution of Multi-hop Communication Distance (MhCD) is either exponential or uniform in free flow and synchronized flow, the distribution of MhCD is either exponential or with a single peak in stop-and-go waves.
考虑驾驶愤怒的元胞自动机交通流模型%Cellular Automaton Model for Urban Traffic Flow Considering Driving Anger
Institute of Scientific and Technical Information of China (English)
郑华荣; 吴超仲; 马晓凤
2013-01-01
Driving behaviors of the angry drivers are quite different from those of the normal drivers.Because of these behavioral differences,driving speed,driving track etc.can be influenced,resulting in a different state of the road traffic flow.This paper re-defined the typical cellular automaton updating rules in mainly three aspects,i.e.,speed,lane change conditions as well as the safe distance and established the periodic boundary two-lane cellular automata traffic flow model considering the characteristics of angry driving behaviors based on NaSch cellular automaton traffic flow model.Both the model constructed and the classical NaSch traffic flow model were simulated in MATLAB and the comparison show that the variance in speed caused by driving anger had the most significant impact on traffic flow.The research can provide as the guidance on establishing models for cellular automaton traffic flow with consideration of driving anger and studying the influence of it to the urban traffic flow; the influence on traffic flow of other driver concerned factors,e.g.,driving fatigue,driving distraction need further research following this method.%驾驶员在愤怒时的驾驶行为表现与正常驾驶时存在较大的差异,这些行为差异会影响车辆的运行速度、运行轨迹等,进而对道路交通流产生影响.文中在NaSch元胞自动机交通流模型的基础上,考虑愤怒驾驶行为的特点,从运行速度、换道条件和安全距离3个方面重新确定元胞更新规则,构建考虑驾驶愤怒情绪的周期边界条件下双车道元胞自动机交通流模型.在MATLAB环境下,对所建模型与普通NaSch交通流模型进行对比仿真分析.结果表明,驾驶愤怒所引起的行驶速度变化对交通流影响明显.
Modeling Hydraulic Failure Process Using Elasto-Plastic Cellular Automaton%水压致裂过程的弹塑性细胞自动机模拟
Institute of Scientific and Technical Information of China (English)
潘鹏志; 冯夏庭; 吴红晓; 孙峰; 周辉
2011-01-01
A self-developed numerical tool, i.e.an elasto-plastic cellular automaton (EPCA) was used to simulate the hydraulic fracturing process of rocks.The modeling method of hydraulic fracturing process of heterogeneous rocks with cellular automaton was developed.With the increase of fluid load, fluid will go into the new cracks.The new fluid seepage boundaries will be formed and the tensile stress induced by fluid will be applied on the crack boundaries.In this process, the mechanical properties and boundary conditions will be updated dynamically.The cellular automaton, which is based on the localization theory,makes this operation more conveniently.With this method, the failure process of wellbore rock specimen under hydraulic pressure was simulated, by considering different heterogeneity and different inner radius of the wellbore.It is concluded that, in hydraulic fracturing process, the critical fluid pressure, crack propagation and final failure patterns etc.are greatly influenced by the heterogeneity of the rock, the boundary geometry etc.%利用自行研发的弹塑性细胞自动机模型和模拟系统,建立了非均质岩石水压致裂过程的细胞自动机模拟方法.该方法能够反映流体在水力梯度作用下进入新生微裂隙、形成新的流体渗流边界而对该边界产生张拉效应,并引起微裂隙的进一步扩展、贯通,最终形成宏观裂纹的过程,可以方便地进行水压致裂过程中边界条件和水力参数的动态更新.同时,研究了不同均质度和井筒内径对水压致裂行为的影响.结果表明,随着井筒内径增加,极限水压力降低,而破裂模式基本相似,模拟结果与典型实验现象吻合较好.
Institute of Scientific and Technical Information of China (English)
N. Sefero(g)lu; B. Kutlu
2007-01-01
The critical behaviour of the three-dimensional Blume-Emery-Grifiiths (BEG) model is investigated at D / J = 0, -0.25 and -1 in the range of-1 ≤ K/J ≤ 0 for J = 100. The simulations are carried out on a simple cubic lattice using the heating algorithm improved from the Creutz cellular automaton (CCA) under periodic boundary conditions. The universality of the model are obtained for re-entrant and double re-entrant phase transitions which occur at certain D/J and K/J parameters, with J and K representing the nearest-neighbour bilinear and biquadratic interactions, and D being the single-ion anisotropy parameter. The values of static critical exponents β, γand v are estimated within the framework of the finite-size scaling theory. The results are compatible with the universal Ising critical behaviour for all continuous phase transitions in these ranges.
Institute of Scientific and Technical Information of China (English)
江欣国; 夏亮
2016-01-01
为研究强制换道及冲突点分布对高速公路临时瓶颈交通流的影响,在NS(NaSch)模型和STCA (symmetric two-lane cellular automata)模型的基础上,引入强制换道规则,根据瓶颈口上游驾驶员心理状态的变化,建立高速公路瓶颈交通流模型.在开口边界条件下,针对不同的安全换道概率、强制换道概率、冲突点距离和冲突区间长度参数,模拟得到瓶颈交通流量和换道频率与车辆到达率的关系.仿真结果表明,安全换道行为对系统流量影响小;强制换道行为是降低瓶颈系统最大流量的主要因素,当安全换道概率为0.5时,强制换道概率从0.0增加至0.1,最大流量下降了17％;冲突点距离的增加缓解了交通拥堵程度,当冲突点距离从1 cell增加至4 cell时,临界车辆到达率上升了4％;冲突区间长度对交通事故风险的影响较大,最大强制换道频率随冲突区间长度的增加而增加.
Properties of a Finite Stochastic Cellular Automaton Toy Model of Earthquakes
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Białecki Mariusz
2015-08-01
Full Text Available Finite version of Random Domino Automaton - a recently proposed toy model of earthquakes - is investigated in detail. Respective set of equations describing stationary state of the FRDA is derived and compared with infinite case. It is shown that for a system of large size, these equations are coincident with RDA equations. We demonstrate a non-existence of exact equations for size N ≥ 5 and propose appropriate approximations, the quality of which is studied in examples obtained within the framework of Markov chains.
22号初等元胞自动机的演化复杂性%EVOLUTION COMPLEXITY OF THE ELEMENTARY CELLULAR AUTOMATON OF RULE 22
Institute of Scientific and Technical Information of China (English)
王益; 江志松
2002-01-01
Cellular automata are the discrete dynamical systems of simple construction but with complex and varied behaviors.In this paper,the elementary cellular automaton of rule 22 is studied by the tools of formal language theory and symbolic dynamics.Its temporal evolution orbits are coarse-grained into evolution sequences and the evolution languages are defined.It is proved that for every n≥2 its width n-evolution language is not regular.
Effect of Driver Scope Awareness in the Lane Changing Maneuvers Using Cellular Automaton Model
Directory of Open Access Journals (Sweden)
Kohei Arai
2013-07-01
Full Text Available This paper investigated the effect of drivers’ visibility and their perception (e.g., to estimate the speed and arrival time of another vehicle on the lane changing maneuver. The term of scope awareness was used to describe the visibility required by the driver to make a perception about road condition and the speed of vehicle that exist in that road. A computer simulation model was conducted to show this driver awareness behavior. This studying attempt to precisely catching the lane changing behavior and illustrate the scope awareness parameter that reflects driver behavior. This paper proposes a simple cellular automata model for studying driver visibility effects of lane changing maneuver and driver perception of estimated speed. Different values of scope awareness were examined to capture its effect on the traffic flow. Simulation results show the ability of this model to capture the important features of lane changing maneuver and revealed the appearance of the short-thin solid line jam and the wide solid line jam in the traffic flow as the consequences of lane changing maneuver.
Lateral Drift Behavior Analysis in Mixed Bicycle Traffic: A Cellular Automaton Model Approach
Directory of Open Access Journals (Sweden)
Xue Feng
2016-01-01
Full Text Available Bicycle movements are always associated with lateral drifts. However, the impacts of lateral drift behavior, as well as variable lateral clearance maintaining behavior due to the variation of drift intensity, on mixed bicycle flow are not clear. This paper establishes a new cellular automata model to study typical characteristics of mixed bicycle traffic induced by lateral drift and its accompanying behavior. Based on derived positive correlation between passing speed and drift speed through survey, the occurrence probability of lateral drift and the degree of maintained lateral clearance are both introduced in accordance with the variance of passing speed. Then, in whole density region, firm conformity between simulation results and actual survey data is reached, which has seldom been achieved in previous studies. It is further verified that speed distortions in intermediate and high density region induced by assumption of constant lateral clearance requirements can be revised by introducing its variability characteristics. In addition, two contrastive impacts of lateral drift behavior are observed. That is, it causes speed fluctuation in low density while alleviating the speed fluctuation in relatively high density. These results are expected to be helpful to improve the simulation performance of mixed bicycle flow as well as depict more realistic vehicle-bicycle conflicts and so on.
International Nuclear Information System (INIS)
A virtual front tracking modified cellular automaton (CA) method is applied to simulate solid phase transformation with a specific crystallographic preferred orientation in a TA15 alloy, to eliminate the dependence of the traditional CA method on space meshing. Simulation results demonstrate the capabilities of the new model in growth anisotropy modeling at large space and time scales, as well as quantitative analysis and description of the precipitated new phase morphology relates to the solute diffusion space by comparison with the diagonal modeling method and rotation of cell sites technique. The isothermal phase transformation kinetics is analysed, which exhibits the desired agreement with the prediction result of the Johnson–Mehl–Avrami analytical equation, thereby a time–temperature-transformation curve is predicted. The crystallography characteristics are consistent with electron backscattered diffraction analysis data. Using the established model, microstructure evolution during the isothermal heat treatment of the TA15 alloy is simulated so that the microstructure heredity with thermal cycling is vividly reflected. (paper)
Matsubara, Takashi; Torikai, Hiroyuki
2016-04-01
Modeling and implementation approaches for the reproduction of input-output relationships in biological nervous tissues contribute to the development of engineering and clinical applications. However, because of high nonlinearity, the traditional modeling and implementation approaches encounter difficulties in terms of generalization ability (i.e., performance when reproducing an unknown data set) and computational resources (i.e., computation time and circuit elements). To overcome these difficulties, asynchronous cellular automaton-based neuron (ACAN) models, which are described as special kinds of cellular automata that can be implemented as small asynchronous sequential logic circuits have been proposed. This paper presents a novel type of such ACAN and a theoretical analysis of its excitability. This paper also presents a novel network of such neurons, which can mimic input-output relationships of biological and nonlinear ordinary differential equation model neural networks. Numerical analyses confirm that the presented network has a higher generalization ability than other major modeling and implementation approaches. In addition, Field-Programmable Gate Array-implementations confirm that the presented network requires lower computational resources.
Martín Del Rey, A.; Rodríguez Sánchez, G.
2015-03-01
The study of the reversibility of elementary cellular automata with rule number 150 over the finite state set 𝔽p and endowed with periodic boundary conditions is done. The dynamic of such discrete dynamical systems is characterized by means of characteristic circulant matrices, and their analysis allows us to state that the reversibility depends on the number of cells of the cellular space and to explicitly compute the corresponding inverse cellular automata.
Tian, Junfang; Ma, Shoufeng; Zhu, Chenqiang; Jiang, Rui; Ding, YaoXian
2015-01-01
This paper proposes an improved cellular automaton traffic flow model based on the brake light model, which takes into account that the desired time gap of vehicles is remarkably larger than one second. Although the hypothetical steady state of vehicles in the deterministic limit corresponds to a unique relationship between speeds and gaps in the proposed model, the traffic states of vehicles dynamically span a two-dimensional region in the plane of speed versus gap, due to the various randomizations. It is shown that the model is able to well reproduce (i) the free flow, synchronized flow, jam as well as the transitions among the three phases; (ii) the evolution features of disturbances and the spatiotemporal patterns in a car-following platoon; (iii) the empirical time series of traffic speed obtained from NGSIM data. Therefore, we argue that a model can potentially reproduce the empirical and experimental features of traffic flow, provided that the traffic states are able to dynamically span a 2D speed-gap...
Tucker, G. E.; Hobley, D. E. J.; Hutton, E.; Gasparini, N. M.; Istanbulluoglu, E.; Adams, J. M.; Nudurupati, S. S.
2015-11-01
CellLab-CTS 2015 is a Python-language software library for creating two-dimensional, continuous-time stochastic (CTS) cellular automaton models. The model domain consists of a set of grid nodes, with each node assigned an integer state-code that represents its condition or composition. Adjacent pairs of nodes may undergo transitions to different states, according to a user-defined average transition rate. A model is created by writing a Python code that defines the possible states, the transitions, and the rates of those transitions. The code instantiates, initializes, and runs one of four object classes that represent different types of CTS model. CellLab-CTS provides the option of using either square or hexagonal grid cells. The software provides the ability to treat particular grid-node states as moving particles, and to track their position over time. Grid nodes may also be assigned user-defined properties, which the user can update after each transition through the use of a callback function. As a component of the Landlab modeling framework, CellLab-CTS models take advantage of a suite of Landlab's tools and capabilities, such as support for standardized input and output.
Effect of Driver Scope Awareness in the Lane Changing Maneuvers Using Cellular Automaton Model
Kohei Arai; Steven Ray Sentinuwo
2013-01-01
This paper investigated the effect of drivers’ visibility and their perception (e.g., to estimate the speed and arrival time of another vehicle) on the lane changing maneuver. The term of scope awareness was used to describe the visibility required by the driver to make a perception about road condition and the speed of vehicle that exist in that road. A computer simulation model was conducted to show this driver awareness behavior. This studying attempt to precisely catching the lane changin...
Institute of Scientific and Technical Information of China (English)
王益; Morita Kenichi
2006-01-01
Symbolic dynamics of cellular automata is introduced by coarse-graining the temporal evolution orbits. Evolution languages are defined. By using the theory of formal languages and automata, the complexity of evolution languages of the elementary cellular automaton of rule 146 is studied and it is proved that its width 1-evolution language is regular, but for every n ≥ 2 its width n-evolution language is not context-free but context-sensitive. Also, the same results hold for the equivalent (under conjugation) elementary cellular automaton of rule 182.
Directory of Open Access Journals (Sweden)
Matthew W Johnston
Full Text Available The Indo-pacific panther grouper (Chromileptes altiveli is a predatory fish species and popular imported aquarium fish in the United States which has been recently documented residing in western Atlantic waters. To date, the most successful marine invasive species in the Atlantic is the lionfish (Pterois volitans/miles, which, as for the panther grouper, is assumed to have been introduced to the wild through aquarium releases. However, unlike lionfish, the panther grouper is not yet thought to have an established breeding population in the Atlantic. Using a proven modeling technique developed to track the lionfish invasion, presented is the first known estimation of the potential spread of panther grouper in the Atlantic. The employed cellular automaton-based computer model examines the life history of the subject species including fecundity, mortality, and reproductive potential and combines this with habitat preferences and physical oceanic parameters to forecast the distribution and periodicity of spread of this potential new invasive species. Simulations were examined for origination points within one degree of capture locations of panther grouper from the United States Geological Survey Nonindigenous Aquatic Species Database to eliminate introduction location bias, and two detailed case studies were scrutinized. The model indicates three primary locations where settlement is likely given the inputs and limits of the model; Jupiter Florida/Vero Beach, the Cape Hatteras Tropical Limit/Myrtle Beach South Carolina, and Florida Keys/Ten Thousand Islands locations. Of these locations, Jupiter Florida/Vero Beach has the highest settlement rate in the model and is indicated as the area in which the panther grouper is most likely to become established. This insight is valuable if attempts are to be made to halt this potential marine invasive species.
Johnston, Matthew W; Purkis, Sam J
2013-01-01
The Indo-pacific panther grouper (Chromileptes altiveli) is a predatory fish species and popular imported aquarium fish in the United States which has been recently documented residing in western Atlantic waters. To date, the most successful marine invasive species in the Atlantic is the lionfish (Pterois volitans/miles), which, as for the panther grouper, is assumed to have been introduced to the wild through aquarium releases. However, unlike lionfish, the panther grouper is not yet thought to have an established breeding population in the Atlantic. Using a proven modeling technique developed to track the lionfish invasion, presented is the first known estimation of the potential spread of panther grouper in the Atlantic. The employed cellular automaton-based computer model examines the life history of the subject species including fecundity, mortality, and reproductive potential and combines this with habitat preferences and physical oceanic parameters to forecast the distribution and periodicity of spread of this potential new invasive species. Simulations were examined for origination points within one degree of capture locations of panther grouper from the United States Geological Survey Nonindigenous Aquatic Species Database to eliminate introduction location bias, and two detailed case studies were scrutinized. The model indicates three primary locations where settlement is likely given the inputs and limits of the model; Jupiter Florida/Vero Beach, the Cape Hatteras Tropical Limit/Myrtle Beach South Carolina, and Florida Keys/Ten Thousand Islands locations. Of these locations, Jupiter Florida/Vero Beach has the highest settlement rate in the model and is indicated as the area in which the panther grouper is most likely to become established. This insight is valuable if attempts are to be made to halt this potential marine invasive species. PMID:24009726
Berkovich, Simon
2015-04-01
The undamental advantage of a Cellular automaton construction foris that it can be viewed as an undetectable absolute frame o reference, in accordance with Lorentz-Poincare's interpretation.. The cellular automaton model for physical poblems comes upon two basic hurdles: (1) How to find the Elemental Rule that, and how to get non-locality from local transformations. Both problems are resolved considering the transfomation rule of mutual distributed synchronization Actually any information proessing device starts with a clocking system. and it turns out that ``All physical phenomena are different aspects of the high-level description of distributed mutual synchronization in a network of digital clocks''. Non-locality comes from two hugely different time-scales of signaling.. The universe is acombinines information and matter processes, These fast spreading diffusion wave solutions create the mechanism of the Holographic Universe. And thirdly Disengaged from synchronization, circular counters can perform memory functions by retaining phases of their oscillations, an idea of Von Neumann'. Thus, the suggested model generates the necessary constructs for the physical world as an Internet of Things. Life emerges due to the specifics of macromolecules that serve as communication means, with the holographic memory...
Institute of Scientific and Technical Information of China (English)
WANG Kuang-fei; LI Bang-sheng; MI Guo-fa; GUO Jing-jie; FU Heng-zhi
2008-01-01
Solute diffusion controlled solidification model was used to simulate the initial stage cellular to dendrite transition of Ti44AI alloys during directional solidification at different velocities. The simulation results show that during this process, a mixed structure composed of cells and dendrites was observed, where secondary dendrites are absent at facing surface with parallel closely spaced dendrites, which agrees with the previous experimental observa-tion. The dendrite spacings are larger than cellular spacings at a given rate, and the columnar grain spacing sharply increases to a maximum as solidification advance to coexistence zone. In addition, simulation also revealed that decreasing the numbers of the seed causes the trend of unstable dendrite transition to increase. Finally, the main influence factors affecting cell/dendrite transition were analyzed, which could be the change of growth rates resulting in slight fluctuations of liquid composition occurred at growth front. The simulation results are in reasonable agreement with the results of previous theoretical models and experimental observation at low cooling rates.
Al-Husari, Maymona; Murdoch, Craig; Webb, Steven D
2014-10-01
Some tumours are known to exhibit an extracellular pH that is more acidic than the intracellular, creating a 'reversed pH gradient' across the cell membrane and this has been shown to affect their invasive and metastatic potential. Tumour hypoxia also plays an important role in tumour development and has been directly linked to both tumour morphology and aggressiveness. In this paper, we present a hybrid mathematical model of intracellular pH regulation that examines the effect of oxygen and pH on tumour growth and morphology. In particular, we investigate the impact of pH regulatory mechanisms on the cellular pH gradient and tumour morphology. Analysis of the model shows that: low activity of the Na+/H+ exchanger or a high rate of anaerobic glycolysis can give rise to a "fingering" tumour morphology; and a high activity of the lactate/H+ symporter can result in a reversed transmembrane pH gradient across a large portion of the tumour mass. Also, the reversed pH gradient is spatially heterogeneous within the tumour, with a normal pH gradient observed within an intermediate growth layer within the spheroid. We also include a fractal dimension analysis of the simulated tumour contours, in which we compare the fractal dimensions of the simulated tumour surfaces with those found experimentally via photomicrographs.
基于元胞自动机理论的协同设计任务调度模型%Collaboration Design Tasks Scheduling Model Based on Cellular Automaton
Institute of Scientific and Technical Information of China (English)
徐鸿翔; 吴晶华; 张向华
2011-01-01
分析了设计任务调度的特点,提出了基于元胞自动机理论的调度模型。对元胞自动机任务调度模型进行了数学描述,对设计任务调度的策略进行了分析,建立了元胞自动机目标调度模型,通过具体算例对所提出的模型进行了验证,表明元胞自动机模型可以有效地进行任务调度的优化。%The characteristic of design tasks scheduling was analyzed,and a collaborative tasks scheduling model based on Cellular Automaton（CA） was put forward.Firstly,mathematics description was done for design tasks scheduling model based on Cellular Automaton.Secondly,the strategy for design tasks scheduling was analyzed.And so,the scheduling target model was established.Finally,a simulation experiment was carried out by using the proposed algorithm.The convergent velocity would be fast and the ability to optimize would be better.
A two-lane cellular automaton traffic flow model with the influence of driver, vehicle and road
Zhao, Han-Tao; Nie, Cen; Li, Jing-Ru; Wei, Yu-Ao
2016-07-01
On the basis of one-lane comfortable driving model, this paper established a two-lane traffic cellular automata model, which improves the slow randomization effected by brake light. Considering the driver psychological characteristics and mixed traffic, we studied the lateral influence between vehicles on adjacent lanes. Through computer simulation, the space-time diagram and the fundamental figure under different conditions are obtained. The study found that aggressive driver makes a slight congestion in low-density traffic and improves the capacity of high-density traffic, when the density exceeds 20pcu/km the more aggressive drivers the greater the flow, when the density below 40pcu/km driver character makes an effect, the more cautious driver, the lower the flow. The ratio of big cars has the same effect as the ratio of aggressive drivers. Brake lights have the greatest impact on traffic flow and when the density exceeds 10pcu/km the traffic flow fluctuates. Under periodic boundary conditions, the disturbance of road length on traffic is minimal. The lateral influence only play a limited role in the medium-density conditions, and only affect the average speed of traffic at low density.
Institute of Scientific and Technical Information of China (English)
丁建勋; 黄海军; 唐铁桥
2009-01-01
Few cellular automaton models of traffic have taken the relationship between the randomization probability of velocity and the specific value of current velocity into account. On the basis of Nagel-Schreckenberg model, this paper presents a modified cellular automaton model in which the randomization probability evolves with the driver' s remembering to historic experience and with the traffic condition around. Numerical simulation results show that the proposed model can reveal the influence of driver's remembering on the traffic and generate higher average velocity and flux.%在NS模型的基础上,利用司机的记忆效应和当前交通环境动态地调整随机慢化概率,从而得到一个改进的交通流元胞自动机模型,数值实验表明,该模型可以很好地刻画司机记忆效应对交通流的影响,记忆效应的引入可以提高平均速度和流量.
Directory of Open Access Journals (Sweden)
M. Ignatieva
1994-06-01
Full Text Available Over the last thirty years the long range goal of the research project of the Speech Statistics (Sp.St. international group is to develop and implement in computer simulation psycholinguistically realistic model of language behavior. This model, named the linguistic automaton /LA/, is a complex of hardware, software lingware /linguistic means of support/ and CALL-ware. The Sp.St. group was developing many programs to model different aspects of natural language /NL/ processing by man. The multilevel and multilingual LA-architecture integrates in a flexible way these programs and provides a control strategy capable of adapting itself to the requirements of a particular task. It permits a modular implementation of LA, making the modification of existing processes and the integration of new capacities in the LA-system easier.
Directory of Open Access Journals (Sweden)
Mondry Adrian
2004-08-01
Full Text Available Abstract Background Many arrhythmias are triggered by abnormal electrical activity at the ionic channel and cell level, and then evolve spatio-temporally within the heart. To understand arrhythmias better and to diagnose them more precisely by their ECG waveforms, a whole-heart model is required to explore the association between the massively parallel activities at the channel/cell level and the integrative electrophysiological phenomena at organ level. Methods We have developed a method to build large-scale electrophysiological models by using extended cellular automata, and to run such models on a cluster of shared memory machines. We describe here the method, including the extension of a language-based cellular automaton to implement quantitative computing, the building of a whole-heart model with Visible Human Project data, the parallelization of the model on a cluster of shared memory computers with OpenMP and MPI hybrid programming, and a simulation algorithm that links cellular activity with the ECG. Results We demonstrate that electrical activities at channel, cell, and organ levels can be traced and captured conveniently in our extended cellular automaton system. Examples of some ECG waveforms simulated with a 2-D slice are given to support the ECG simulation algorithm. A performance evaluation of the 3-D model on a four-node cluster is also given. Conclusions Quantitative multicellular modeling with extended cellular automata is a highly efficient and widely applicable method to weave experimental data at different levels into computational models. This process can be used to investigate complex and collective biological activities that can be described neither by their governing differentiation equations nor by discrete parallel computation. Transparent cluster computing is a convenient and effective method to make time-consuming simulation feasible. Arrhythmias, as a typical case, can be effectively simulated with the methods
基于元胞自动机带有干预机制的传染病模型%A cellular automaton model with medical intervention for epidemic propagation
Institute of Scientific and Technical Information of China (English)
关超; 彭云; 袁文燕
2011-01-01
Based on the classical SEIR ( susceptible, exposed, infections, and recovered) model, a cellular automaton (CA) model with medical intervention is proposed to simulate epidemic propagation. The model describes the outbreak of infectious diseases dynamically at different time steps. The newly constructed rules of neighborhood can not only reflect the regional characteristics of epidemic propagation, but also indicate flow characteristics. The CA model can reflect the characteristics of spread, such as periodic and fade-type transmission and the peak value of outbreak. The effects of medical intervention and vaccination strategy have been studied. The proposed model can serve as a quantitative basis for future medical intervention.%在经典SEIR模型的基础上,提出了基于元胞自动机带有干预机制的传染病模型,模拟了在医疗干预下传染病的传播过程,动态刻画了不同时间段疾病的爆发情况,体现了传染病区域性传播的特性以及流动性传染的特点.不同传染病各自传播的特征如周期性传播、消退型传播、爆发等,均能在模拟中体现出来,符合传染病传播的规律.仿真结果表明医疗干预和疫苗等医疗措施对传染病传播起到一定的抑制作用,量化了医疗干预的效果,为采取合理的预防及干预手段提供了量化依据.
Gopalakrishnan, Manoj; Forsten-Williams, Kimberly; Tauber, Uwe C.
2003-01-01
The binding of basic fibroblast growth factor (FGF-2) to its cell surface receptor (CSR) and subsequent signal transduction is known to be enhanced by Heparan Sulfate Proteoglycans (HSPGs). HSPGs bind FGF-2 with low affinity and likely impact CSR-mediated signaling via stabilization of FGF-2-CSR complexes via association with both the ligand and the receptor. What is unknown is whether HSPG associates with CSR in the absence of FGF-2. In this paper, we determine conditions by which pre-associ...
Harun, R.
2013-05-01
This research provides an opportunity of collaboration between urban planners and modellers by providing a clear theoretical foundations on the two most widely used urban land use models, and assessing the effectiveness of applying the models in urban planning context. Understanding urban land cover change is an essential element for sustainable urban development as it affects ecological functioning in urban ecosystem. Rapid urbanization due to growing inclination of people to settle in urban areas has increased the complexities in predicting that at what shape and size cities will grow. The dynamic changes in the spatial pattern of urban landscapes has exposed the policy makers and environmental scientists to great challenge. But geographic science has grown in symmetry to the advancements in computer science. Models and tools are developed to support urban planning by analyzing the causes and consequences of land use changes and project the future. Of all the different types of land use models available in recent days, it has been found by researchers that the most frequently used models are Cellular Automaton (CA) and Artificial Neural Networks (ANN) models. But studies have demonstrated that the existing land use models have not been able to meet the needs of planners and policy makers. There are two primary causes identified behind this prologue. First, there is inadequate understanding of the fundamental theories and application of the models in urban planning context i.e., there is a gap in communication between modellers and urban planners. Second, the existing models exclude many key drivers in the process of simplification of the complex urban system that guide urban spatial pattern. Thus the models end up being effective in assessing the impacts of certain land use policies, but cannot contribute in new policy formulation. This paper is an attempt to increase the knowledge base of planners on the most frequently used land use model and also assess the
Finite Random Domino Automaton
Bialecki, Mariusz
2012-01-01
Finite version of Random Domino Automaton (FRDA) - recently proposed a toy model of earthquakes - is investigated. Respective set of equations describing stationary state of the FRDA is derived and compared with infinite case. It is shown that for the system of big size, these equations are coincident with RDA equations. We demonstrate a non-existence of exact equations for size N bigger then 4 and propose appropriate approximations, the quality of which is studied in examples obtained within Markov chains framework. We derive several exact formulas describing properties of the automaton, including time aspects. In particular, a way to achieve a quasi-periodic like behaviour of RDA is presented. Thus, based on the same microscopic rule - which produces exponential and inverse-power like distributions - we extend applicability of the model to quasi-periodic phenomena.
On reversibility of cellular automata with periodic boundary conditions
Energy Technology Data Exchange (ETDEWEB)
Nobe, Atsushi [Graduate School of Engineering Science, Osaka University, Machikaneyama-cho 1-3, Toyonaka, Osaka 560-8531 (Japan); Yura, Fumitaka [Imai Quantum Computing and Information Project, ERATO, JST, Daini Hongo White Bldg 201, 5-28-3 Hongo, Bunkyo, Tokyo 113-0033 (Japan)
2004-06-04
Reversibility of one-dimensional cellular automata with periodic boundary conditions is discussed. It is shown that there exist exactly 16 reversible elementary cellular automaton rules for infinitely many cell sizes by means of a correspondence between elementary cellular automaton and the de Bruijn graph. In addition, a sufficient condition for reversibility of three-valued and two-neighbour cellular automaton is given.
Directory of Open Access Journals (Sweden)
Chen Shijia
2013-11-01
Full Text Available Dans le domaine du soudage, les propriétés finales du cordon sont fortement liées à la structure de grains développée au cours des procédés de fusion / resolidification. La maîtrise des propriétés de l'assemblage final passe ainsi par une amélioration de la connaissance de sa structure de ce domaine. Dans cet objectif, un modèle couplé Automates Cellulaires – Eléments Finis est proposé pour simuler le développement, en volume, de cette structure, dans le cadre du soudage TIG. Ce modèle est appliqué au soudage d'acier Duplex 2202 et l'évolution de la structure de grains selon les paramètres procédés est discutée. In the welding area, the final properties of the weld bead are mainly induced by the grain structure developed during the melting and solidification steps. The mastery of the properties of the joining will be achieved with a better knowledge of the developed grain structure. A 3D coupled Cellular Automaton – Finite Element model is proposed in order to simulate the grains development in TIG process. This model is applied to the welding of a duplex stainless steel grade. The grain structure evolution is discussed for the various process parameters.
Cellular Dynamic Simulator: An Event Driven Molecular Simulation Environment for Cellular Physiology
Byrne, Michael J.; Waxham, M. Neal; Kubota, Yoshihisa
2010-01-01
In this paper, we present the Cellular Dynamic Simulator (CDS) for simulating diffusion and chemical reactions within crowded molecular environments. CDS is based on a novel event driven algorithm specifically designed for precise calculation of the timing of collisions, reactions and other events for each individual molecule in the environment. Generic mesh based compartments allow the creation / importation of very simple or detailed cellular structures that exist in a 3D environment. Multi...
Cellular Dynamic Simulator: An Event Driven Molecular Simulation Environment for Cellular Physiology
Byrne, Michael J.; Waxham, M. Neal; Kubota, Yoshihisa
2010-01-01
In this paper, we present the Cellular Dynamic Simulator (CDS) for simulating diffusion and chemical reactions within crowded molecular environments. CDS is based on a novel event driven algorithm specifically designed for precise calculation of the timing of collisions, reactions and other events for each individual molecule in the environment. Generic mesh based compartments allow the creation / importation of very simple or detailed cellular structures that exist in a 3D environment. Multiple levels of compartments and static obstacles can be used to create a dense environment to mimic cellular boundaries and the intracellular space. The CDS algorithm takes into account volume exclusion and molecular crowding that may impact signaling cascades in small sub-cellular compartments such as dendritic spines. With the CDS, we can simulate simple enzyme reactions; aggregation, channel transport, as well as highly complicated chemical reaction networks of both freely diffusing and membrane bound multi-protein complexes. Components of the CDS are generally defined such that the simulator can be applied to a wide range of environments in terms of scale and level of detail. Through an initialization GUI, a simple simulation environment can be created and populated within minutes yet is powerful enough to design complex 3D cellular architecture. The initialization tool allows visual confirmation of the environment construction prior to execution by the simulator. This paper describes the CDS algorithm, design implementation, and provides an overview of the types of features available and the utility of those features are highlighted in demonstrations. PMID:20361275
Two Phase Flow Simulation Using Cellular Automata
International Nuclear Information System (INIS)
The classical mathematical treatment of two-phase flows is based on the average of the conservation equations for each phase.In this work, a complementary approach to the modeling of these systems based on statistical population balances of aut omata sets is presented.Automata are entities defined by mathematical states that change following iterative rules representing interactions with the neighborhood.A model of automata for two-phase flow simulation is presented.This model consists of fie lds of virtual spheres that change their volumes and move around a certain environment.The model is more general than the classical cellular automata in two respects: the grid of cellular automata is dismissed in favor of a trajectory generator, and the rules of interaction involve parameters representing the actual physical interactions between phases.Automata simulation was used to study unsolved two-phase flow problems involving high heat flux rates. One system described in this work consists of a vertical channel with saturated water at normal pressure heated from the lower surface.The heater causes water to boil and starts the bubble production.We used cellular automata to describe two-phase flows and the interaction with the heater.General rule s for such cellular automata representing bubbles moving in stagnant liquid were used, with special attention to correct modeling of different mechanisms of heat transfer.The results of the model were compared to previous experiments and correlations finding good agreement.One of the most important findings is the confirmation of Kutateladze's idea about a close relation between the start of critical heat flux and a change in the flow's topology.This was analyzed using a control volume located in the upper surface of the heater.A strong decrease in the interfacial surface just before the CHF start was encountered.The automata describe quite well some characteristic parameters such as the shape of the local void fraction in the
Malarz, Krzysztof; Kułakowski, Krzysztof
2014-01-01
The problem `human and work' in a model working group is investigated by means of cellular automata technique. Attitude of members of a group towards work is measured by indicator of loyalty to the group (the number of underloaded agents who carry out their tasks), and lack of loyalty (the number of overloaded agents, who give their tasks to other agents). Initially, all agents realize scheduled tasks one-by-one. Agents with the number of scheduled tasks larger than a given threshold change their strategy to `overloaded' one and start avoiding completing tasks by passing them to their colleagues. Optionally, in some conditions, we allow agents to return to `underloaded' state; hence the rule is hysteretic. Results are presented on an influence of i) the density of tasks, ii) the threshold number of tasks assigned to the agents' forcing him/her for strategy change on the system efficiency. We show that a `black' scenario of the system stacking in a jammed phase (with all agents being in overloaded state and ha...
Motzkin numbers out of Random Domino Automaton
Białecki, Mariusz
2011-01-01
Motzkin numbers are derived from a special case of Random Domino Automaton - recently proposed toy model of earthquakes. An exact solution of the set of equations describing stationary state of Random Domino Automaton in "inverse-power" case is presented. A link with Motzkin numbers allows to present explicit form of asymptotic behaviour of the automaton.
The cellular automaton interpretation of quantum mechanics
't Hooft, Gerard
2016-01-01
This book presents the deterministic view of quantum mechanics developed by Nobel Laureate Gerard 't Hooft. Dissatisfied with the uncomfortable gaps in the way conventional quantum mechanics meshes with the classical world, 't Hooft has revived the old hidden variable ideas, but now in a much more systematic way than usual. In this, quantum mechanics is viewed as a tool rather than a theory. The book presents examples of models that are classical in essence, but can be analysed by the use of quantum techniques, and argues that even the Standard Model, together with gravitational interactions, might be viewed as a quantum mechanical approach to analysing a system that could be classical at its core. He shows how this approach, even though it is based on hidden variables, can be plausibly reconciled with Bell's theorem, and how the usual objections voiced against the idea of ‘superdeterminism' can be overcome, at least in principle. This framework elegantly explains - and automatically cures - the problems of...
Simulated Annealing for Location Area Planning in Cellular networks
Prajapati, N. B.; R. R. Agravat; Hasan, M I
2010-01-01
LA planning in cellular network is useful for minimizing location management cost in GSM network. In fact, size of LA can be optimized to create a balance between the LA update rate and expected paging rate within LA. To get optimal result for LA planning in cellular network simulated annealing algorithm is used. Simulated annealing give optimal results in acceptable run-time.
Simulated Annealing for Location Area Planning in Cellular networks
Directory of Open Access Journals (Sweden)
N. B. Prajapati
2010-03-01
Full Text Available LA planning in cellular network is useful for minimizing location management cost in GSM network. Infact, size of LA can be optimized to create a balance between the LA update rate and expected pagingrate within LA. To get optimal result for LA planning in cellular network simulated annealing algorithmis used. Simulated annealing give optimal results in acceptable run-time.
Process Expression of Security Automaton
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Security is an essential aspect for mobile systems. Usually, mobile system modeling and its security policies specification are realized in different techniques. So when constructed a mobile system using formal methods it is difficult to verify if the system comply with any given security policies. A method was introduced to express security automata which specifying enforceable security policies as processes in an extended π-calculus. In this extended π-calculus, an exception termination process was introduced, called bad. Any input which violating a security automaton will correspond to a step of transformation of the process that specifying the security automaton to exception termination process. Our method shows that any security automata which specifying enforceable security policies would decide a process in the extended π-calculus.
Cellular Automata Simulations - Tools and Techniques
Fuks, Henryk
2010-01-01
We presented an overview of basic issues associated with CA simulations, concentrating on selected problems which, in the mind of the author, deserve closer attention. We also demonstrated how HCELL can be used to perform some typical CA simulation tasks. Obviously, many important topics have been omitted. In particular, the issue of dimensionality of space has not been addressed, and yet many important CA models require 2D, 3D, and higher dimensional lattices. Some collective phenomena in CA...
Simulating Complex Systems by Cellular Automata
Kroc, Jiri; Hoekstra, Alfons G
2010-01-01
Deeply rooted in fundamental research in Mathematics and Computer Science, Cellular Automata (CA) are recognized as an intuitive modeling paradigm for Complex Systems. Already very basic CA, with extremely simple micro dynamics such as the Game of Life, show an almost endless display of complex emergent behavior. Conversely, CA can also be designed to produce a desired emergent behavior, using either theoretical methodologies or evolutionary techniques. Meanwhile, beyond the original realm of applications - Physics, Computer Science, and Mathematics – CA have also become work horses in very different disciplines such as epidemiology, immunology, sociology, and finance. In this context of fast and impressive progress, spurred further by the enormous attraction these topics have on students, this book emerges as a welcome overview of the field for its practitioners, as well as a good starting point for detailed study on the graduate and post-graduate level. The book contains three parts, two major parts on th...
Simulation of earthquakes with cellular automata
Directory of Open Access Journals (Sweden)
P. G. Akishin
1998-01-01
Full Text Available The relation between cellular automata (CA models of earthquakes and the Burridge–Knopoff (BK model is studied. It is shown that the CA proposed by P. Bak and C. Tang,although they have rather realistic power spectra, do not correspond to the BK model. We present a modification of the CA which establishes the correspondence with the BK model.An analytical method of studying the evolution of the BK-like CA is proposed. By this method a functional quadratic in stress release, which can be regarded as an analog of the event energy, is constructed. The distribution of seismic events with respect to this “energy” shows rather realistic behavior, even in two dimensions. Special attention is paid to two-dimensional automata; the physical restrictions on compression and shear stiffnesses are imposed.
Probing Cellular Dynamics with Mesoscopic Simulations
DEFF Research Database (Denmark)
Shillcock, Julian C.
2010-01-01
. But these models struggle to represent processes that are localized in space and time or involve the transport of material through a crowded environment. A novel class of mesoscopic simulation techniques are now able to span length and time scales from nanometers to microns for hundreds of microseconds, and may......-based simulation techniques cannot capture such a broad range. Consequently, at long length scales, models have often been of the Mass Action variety, in which molecular constituents are represented by density fields that vary continuously in space and time, rather than involving discrete molecules...
DEFF Research Database (Denmark)
Weyland, Mathias; Fellermann, Harold; Hadorn, Maik;
2013-01-01
In this paper, we propose the MATCHIT Automaton (MA), a theoretical framework that shows how to improve the yield of the synthesis of chemical polymer reactions. This is achieved by separating sub-steps of the path of syn- thesis into compartments. We use chemical containers (chemtainers) to carry...... the substances through a sequence of compartments. We describe the MA in mathematical terms and show how it can be configured automatically in order to synthesize a branched target polymer given as input. We discuss how the MA models compartmentalized structures found in cells, such as the endoplasmatic...
Simulation of Power Control and Diversity of Cellular CDMA
Institute of Scientific and Technical Information of China (English)
RomanPichna; QiangWang; 等
1995-01-01
This paper presents a software package developed by the authors for the simulation of a cellular code division multiple access(CDMA)system.In the simulated system,a number of fac-tors are taken into account including time-correlated fading and shadowing,delays in power control and diversity ,errors in power control commands,soft hand-off,base station diversity,and pilots and diversity transmissions,contributions to the interference.
Reversible quantum cellular automata
Schumacher, B
2004-01-01
We define quantum cellular automata as infinite quantum lattice systems with discrete time dynamics, such that the time step commutes with lattice translations and has strictly finite propagation speed. In contrast to earlier definitions this allows us to give an explicit characterization of all local rules generating such automata. The same local rules also generate the global time step for automata with periodic boundary conditions. Our main structure theorem asserts that any quantum cellular automaton is structurally reversible, i.e., that it can be obtained by applying two blockwise unitary operations in a generalized Margolus partitioning scheme. This implies that, in contrast to the classical case, the inverse of a nearest neighbor quantum cellular automaton is again a nearest neighbor automaton. We present several construction methods for quantum cellular automata, based on unitaries commuting with their translates, on the quantization of (arbitrary) reversible classical cellular automata, on quantum c...
Mosquito population dynamics from cellular automata-based simulation
Syafarina, Inna; Sadikin, Rifki; Nuraini, Nuning
2016-02-01
In this paper we present an innovative model for simulating mosquito-vector population dynamics. The simulation consist of two stages: demography and dispersal dynamics. For demography simulation, we follow the existing model for modeling a mosquito life cycles. Moreover, we use cellular automata-based model for simulating dispersal of the vector. In simulation, each individual vector is able to move to other grid based on a random walk. Our model is also capable to represent immunity factor for each grid. We simulate the model to evaluate its correctness. Based on the simulations, we can conclude that our model is correct. However, our model need to be improved to find a realistic parameters to match real data.
Multi Car Elevator Control by using Learning Automaton
Shiraishi, Kazuaki; Hamagami, Tomoki; Hirata, Hironori
We study an adaptive control technique for multi car elevators (MCEs) by adopting learning automatons (LAs.) The MCE is a high performance and a near-future elevator system with multi shafts and multi cars. A strong point of the system is that realizing a large carrying capacity in small shaft area. However, since the operation is too complicated, realizing an efficient MCE control is difficult for top-down approaches. For example, “bunching up together" is one of the typical phenomenon in a simple traffic environment like the MCE. Furthermore, an adapting to varying environment in configuration requirement is a serious issue in a real elevator service. In order to resolve these issues, having an autonomous behavior is required to the control system of each car in MCE system, so that the learning automaton, as the solutions for this requirement, is supposed to be appropriate for the simple traffic control. First, we assign a stochastic automaton (SA) to each car control system. Then, each SA varies its stochastic behavior distributions for adapting to environment in which its policy is evaluated with each passenger waiting times. That is LA which learns the environment autonomously. Using the LA based control technique, the MCE operation efficiency is evaluated through simulation experiments. Results show the technique enables reducing waiting times efficiently, and we confirm the system can adapt to the dynamic environment.
Simulation of Quantum Mechanics Using Reactive Programming
Boussinot, Frédéric
2011-01-01
We implement in a reactive programming framework a simulation of three aspects of quantum mechanics: self-interference, state superposition, and entanglement. The simulation basically consists in a cellular automaton embedded in a synchronous environment which defines global discrete instants and broadcast events. The implementation shows how a simulation of fundamental aspects of quantum mechanics can be obtained from the synchronous parallel combination of a small number of elementary compo...
Simulation of root forms using cellular automata model
Energy Technology Data Exchange (ETDEWEB)
Winarno, Nanang, E-mail: nanang-winarno@upi.edu; Prima, Eka Cahya [International Program on Science Education, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudi no 229, Bandung40154 (Indonesia); Afifah, Ratih Mega Ayu [Department of Physics Education, Post Graduate School, Universitas Pendidikan Indonesia, Jl. Dr. Setiabudi no 229, Bandung40154 (Indonesia)
2016-02-08
This research aims to produce a simulation program for root forms using cellular automata model. Stephen Wolfram in his book entitled “A New Kind of Science” discusses the formation rules based on the statistical analysis. In accordance with Stephen Wolfram’s investigation, the research will develop a basic idea of computer program using Delphi 7 programming language. To best of our knowledge, there is no previous research developing a simulation describing root forms using the cellular automata model compared to the natural root form with the presence of stone addition as the disturbance. The result shows that (1) the simulation used four rules comparing results of the program towards the natural photographs and each rule had shown different root forms; (2) the stone disturbances prevent the root growth and the multiplication of root forms had been successfully modeled. Therefore, this research had added some stones, which have size of 120 cells placed randomly in the soil. Like in nature, stones cannot be penetrated by plant roots. The result showed that it is very likely to further develop the program of simulating root forms by 50 variations.
A hybrid parallel framework for the cellular Potts model simulations
Energy Technology Data Exchange (ETDEWEB)
Jiang, Yi [Los Alamos National Laboratory; He, Kejing [SOUTH CHINA UNIV; Dong, Shoubin [SOUTH CHINA UNIV
2009-01-01
The Cellular Potts Model (CPM) has been widely used for biological simulations. However, most current implementations are either sequential or approximated, which can't be used for large scale complex 3D simulation. In this paper we present a hybrid parallel framework for CPM simulations. The time-consuming POE solving, cell division, and cell reaction operation are distributed to clusters using the Message Passing Interface (MPI). The Monte Carlo lattice update is parallelized on shared-memory SMP system using OpenMP. Because the Monte Carlo lattice update is much faster than the POE solving and SMP systems are more and more common, this hybrid approach achieves good performance and high accuracy at the same time. Based on the parallel Cellular Potts Model, we studied the avascular tumor growth using a multiscale model. The application and performance analysis show that the hybrid parallel framework is quite efficient. The hybrid parallel CPM can be used for the large scale simulation ({approx}10{sup 8} sites) of complex collective behavior of numerous cells ({approx}10{sup 6}).
Simulation of root forms using cellular automata model
International Nuclear Information System (INIS)
This research aims to produce a simulation program for root forms using cellular automata model. Stephen Wolfram in his book entitled “A New Kind of Science” discusses the formation rules based on the statistical analysis. In accordance with Stephen Wolfram’s investigation, the research will develop a basic idea of computer program using Delphi 7 programming language. To best of our knowledge, there is no previous research developing a simulation describing root forms using the cellular automata model compared to the natural root form with the presence of stone addition as the disturbance. The result shows that (1) the simulation used four rules comparing results of the program towards the natural photographs and each rule had shown different root forms; (2) the stone disturbances prevent the root growth and the multiplication of root forms had been successfully modeled. Therefore, this research had added some stones, which have size of 120 cells placed randomly in the soil. Like in nature, stones cannot be penetrated by plant roots. The result showed that it is very likely to further develop the program of simulating root forms by 50 variations
Institute of Scientific and Technical Information of China (English)
杨奕; 施帮利; 徐鹏
2011-01-01
在一维元胞自动机交通流SDNS模型的基础上,建立了基于选择性随机减速的元胞自动机模型（Select-CA模型）.驾驶员可根据与前车的间距变化选择不同的随机减速方式,并定义了不同随机减速方式的选择条件.通过计算机数值模拟发现,当减速方式可变时,模型模拟得到的交通流流量较大,且流量、速度和车辆比例与随机减速概率密切相关.与SDNS模型相比,Select-CA模型减少了车流的阻塞现象,提高了道路的通行能力.%Based on the SDNS cellular automata（CA） traffic model,an improved single-lane traffic CA model with consideration of selectivity random deceleration is proposed.The model considers the vehicles adopting different random deceleration rules under the mutative traffic condition and introduces the rules of deceleration probability change.Numerical simulations show a complicated evolution process of traffic flow.Different values of deceleration probability have different effects on the mixed traffic flow.In the evolution process,the traffic flow is higher in the new model than in the SDNS model,indicating that the stop status of the whole traffic flow has been improved.
Modeling and simulation for train control system using cellular automata
Institute of Scientific and Technical Information of China (English)
LI; KePing; GAO; ZiYou; YANG; LiXing
2007-01-01
Train control system plays a key role in railway traffic. Its function is to manage and control the train movement on railway networks. In our previous works, based on the cellular automata (CA) model, we proposed several models and algorithms for simulating the train movement under different control system conditions. However, these models are only suitable for some simple traffic conditions. Some basic factors, which are important for train movement, are not considered. In this paper, we extend these models and algorithms and give a unified formula. Using the proposed method, we analyze and discuss the space-time diagram of railway traffic flow and the trajectories of the train movement. The numerical simulation and analytical results demonstrate that the unified CA model is an effective tool for simulating the train control system.
Study and Simulation of Traffic Behavior in Cellular Network
Madhup, D. K.; Shrestha, C. L.; Sharma, R. K.
2007-07-01
Cellular radio systems accommodate a large number of users with a limited radio spectrum. The concept of trunking allows a large number of users to share the relatively small number of channels in a cell by providing access to each user, on demand, from a pool of available channels. Traffic engineering deals with provisioning of communication circuits in a given area for a number of subscribers with a required grade of service. Traffic in any cell depends upon the number of users, the average request rate and average call duration. Certain number of channels is required for the required GOS. To design an optimum capacity cellular system, traffic behavior on that system is important. The number of channel required can be estimated by using Erlang formula and Erlang table. Erlang table is not always useful to calculate the probability of blocking in various complex scenarios such as channel borrowing strategies. When the total number of channel available in a given cell are divided to serve partly for newly generated calls and partly for handover calls, and if they use dynamic channel assignment strategies like channel borrowing, then the probability of blocking can't be calculated from Erlang table. Simulation model of the behavior help us to determine the blocking and the channel utilization while using various channel assignment strategies. The title "Study and Simulation of Traffic Behavior in Cellular Network" entail the study of the blocking probability of traffic in cellular network for static channel assignment strategies and dynamic channel borrowing strategies through MATLAB programming language and graphic user interface (GUI). The result shows that the dynamic scheme can perform better than static maximizing the overall utilization of the circuits and minimizing the overall blocking.
Cellular automata simulation of traffic including cars and bicycles
Vasic, Jelena; Ruskin, Heather J.
2012-04-01
As 'greening' of all aspects of human activity becomes mainstream, transportation science is also increasingly focused around sustainability. Modal co-existence between motorised and non-motorised traffic on urban networks is, in this context, of particular interest for traffic flow modelling. The main modelling problems here are posed by the heterogeneity of vehicles, including size and dynamics, and by the complex interactions at intersections. Herein we address these with a novel technique, based on one-dimensional cellular automata components, for modelling network infrastructure and its occupancy by vehicles. We use this modelling approach, together with a corresponding vehicle behaviour model, to simulate combined car and bicycle traffic for two elemental scenarios-examples of components that would be used in the building of an arbitrary network. Results of simulations performed on these scenarios, (i) a stretch of road and (ii) an intersection causing conflict between cars and bicycles sharing a lane, are presented and analysed.
Institute of Scientific and Technical Information of China (English)
魏雷; 林鑫; 王猛; 黄卫东
2012-01-01
本文基于MeshTV界面重构算法,发展了二元合金凝固自由枝晶生长的元胞自动机（cellular automaton,CA）模型.通过采用MeshTV界面重构算法,在细化的界面元胞内重构出了固液界面的位置.在此基础上,发展了一种同时适合描述纯物质与合金凝固界面生长的动力学模型.与非界面重构的CA模型相比,本文所发展的模型可以在较大的网格尺寸下实现模型的收敛,同时网格各向异性不明显,且能够反映界面能各向异性参数ε对自由枝晶生长的影响.在ε=0.02时,通过与描述自由枝晶生长的LGK理论模型相比较,发现计算的枝晶尖端速度与LGK理论模型的预测符合较好,而计算的枝晶尖端半径比LGK理论预测值大于约20%.%In this paper, cellular automata （CA） model for free dendritic growth of alloy is presented, in which the interface cell is refined by MeshTV interface reconstruction algorithm. In the present CA model, the growth kinetic for both pure material and alloy is used. The effect of interfacial energy anisotropy parameter e is validated in the CA model. The dendrite tip growth velocity and tip radius are compared with those of the LGK theoretical model, when e = 0.02.
Computer simulation of aeolian bedforms
Institute of Scientific and Technical Information of China (English)
苗天德; 慕青松; 武生智
2001-01-01
A discrete model is set up using the cellular automaton method and applied to simulate the formation and evolution of aeolian bedforms. The calculated bedforms resemble the actual shape of natural sand ripples and dunes.This reveals that the sand movement is a typical nonlinear dynamical process, and that the nesting configuration of sand ripples, dunes and draas are a self-organized system with a fractal characteristic, and evotves simultaneously at various scales in the sand-airflow.
Cellular automata simulation of medication-induced autoimmune diseases
Stauffer, Dietrich; Proykova, Ana
2004-01-01
We implement the cellular automata model proposed by Stauffer and Weisbuch in 1992 to describe the response of the immune system to antigens in the presence of medications. The model contains two thresholds, θ1 and θ2, suggested by de Boer, Segel, and Perelson to present the minimum field needed to stimulate the proliferation of the receptors and to suppress it, respectively. The influence of the drug is mimicked by increasing the second threshold, thus enhancing the immune response. If this increase is too strong, the immune response is triggered in the whole immune repertoire, causing it to attack the own body. This effect is seen in our simulations to depend both on the ratio of the thresholds and on their absolute values.
APRON: A Cellular Processor Array Simulation and Hardware Design Tool
Directory of Open Access Journals (Sweden)
David R. W. Barr
2009-01-01
Full Text Available We present a software environment for the efficient simulation of cellular processor arrays (CPAs. This software (APRON is used to explore algorithms that are designed for massively parallel fine-grained processor arrays, topographic multilayer neural networks, vision chips with SIMD processor arrays, and related architectures. The software uses a highly optimised core combined with a flexible compiler to provide the user with tools for the design of new processor array hardware architectures and the emulation of existing devices. We present performance benchmarks for the software processor array implemented on standard commodity microprocessors. APRON can be configured to use additional processing hardware if necessary and can be used as a complete graphical user interface and development environment for new or existing CPA systems, allowing more users to develop algorithms for CPA systems.
Institute of Scientific and Technical Information of China (English)
张剑; 董力耘
2011-01-01
提出描述交通灯控制下城市道路交通流动力学演化过程的元胞自动机模型,其中交通灯对于路段上车辆的影响是全局的,驾驶员可根据交通灯的状态及时调整驾驶行为,同时还考虑前方车辆的预期运动.该模型中车辆的运动更加平滑,符合实际交通现象.应用模型中的驾驶策略,可以有效地减少怠速和速度骤减的状态,从而减少机动车的尾气排放.%A cellular automaton model is proposed to depict dynamical evolution of urban traffic flow under control of traffic lights on a single-lane road. It is assumed that traffic lights have global influence on vehicles, and drivers adjust their behaviors timely according to the states of traffic light. Furthermore, anticipation effect is taken into account to predict the movement of vehicles in the presence of traffic lights. Therefore vehicles can move forward more smoothly. This is in agreement with the actual situation. It is expected that using the proposed strategy in driving can help reduce vehicle idling and abrupt deceleration and lead to less emission of exhausted gas.
Simulating the Immune Response on a Distributed Parallel Computer
Castiglione, F.; Bernaschi, M.; Succi, S.
The application of ideas and methods of statistical mechanics to problems of biological relevance is one of the most promising frontiers of theoretical and computational mathematical physics.1,2 Among others, the computer simulation of the immune system dynamics stands out as one of the prominent candidates for this type of investigations. In the recent years immunological research has been drawing increasing benefits from the resort to advanced mathematical modeling on modern computers.3,4 Among others, Cellular Automata (CA), i.e., fully discrete dynamical systems evolving according to boolean laws, appear to be extremely well suited to computer simulation of biological systems.5 A prominent example of immunological CA is represented by the Celada-Seiden automaton, that has proven capable of providing several new insights into the dynamics of the immune system response. To date, the Celada-Seiden automaton was not in a position to exploit the impressive advances of computer technology, and notably parallel processing, simply because no parallel version of this automaton had been developed yet. In this paper we fill this gap and describe a parallel version of the Celada-Seiden cellular automaton aimed at simulating the dynamic response of the immune system. Details on the parallel implementation as well as performance data on the IBM SP2 parallel platform are presented and commented on.
About Strongly Universal Cellular Automata
Directory of Open Access Journals (Sweden)
Maurice Margenstern
2013-09-01
Full Text Available In this paper, we construct a strongly universal cellular automaton on the line with 11 states and the standard neighbourhood. We embed this construction into several tilings of the hyperbolic plane and of the hyperbolic 3D space giving rise to strongly universal cellular automata with 10 states.
Direct Simulation of a Solidification Benchmark Experiment
Carozzani, Tommy; Gandin, Charles-André; Digonnet, Hugues; Bellet, Michel; Zaidat, Kader; Fautrelle, Yves
2013-01-01
International audience A solidification benchmark experiment is simulated using a three-dimensional cellular automaton-finite element solidification model. The experiment consists of a rectangular cavity containing a Sn-3 wt pct Pb alloy. The alloy is first melted and then solidified in the cavity. A dense array of thermocouples permits monitoring of temperatures in the cavity and in the heat exchangers surrounding the cavity. After solidification, the grain structure is revealed by metall...
Wang, Zhijun; Wang, Jincheng; Li, Junjie; Yang, Gencang; Zhou, Yaohe
2011-10-01
Using a quantitative phase-field model, a systematic investigation of cellular growth in directional solidification is carried out with emphasis on the selection of cellular tip undercooling, tip radius, and cellular spacing. Previous analytical models of cellular growth are evaluated according to the phase-field simulation results. The results show that cellular tip undercooling and tip radius not only depend on the pulling velocity and thermal gradient, but also depend on the cellular interaction related to the cellular spacing. The cellular interaction results in a finite stable range of cellular spacing. The lower limit is determined by the submerging mechanism while the upper limit comes from the tip splitting instability corresponding to the absence of the cellular growth solution, both of which can be obtained from phase-field simulation. Further discussions on the phase-field results also present an analytical method to predict the lower limit. Phase-field simulations on cell elimination between cells with equal spacing validate the finite range of cellular spacing and give deep insight into the cellular doublon and oscillatory instability between cell elimination and tip splitting.
Cellular automata modelling of phase-change memories
Institute of Scientific and Technical Information of China (English)
Wanhua Yu; David Wright
2008-01-01
A novel approach to modelling phase-transition processes in phase change materials used for optical and electrical data storage applications is presented. The model is based on a cellular automaton (CA) approach to predict crystallization behaviour that is linked to thermal and electrical simulations to enable the study of the data writing and erasing processes. The CA approach is shown to be able to predict the evolution of the microstructure during the rapid heating and cooling cycles pertinent to data storage technology, and maps crystallization behaviour on the nanoscale. A simple example based on possible future nonvolatile phase-change random access solid-state memory is presented.
Car Deceleration Considering Its Own Velocity in Cellular Automata Model
Institute of Scientific and Technical Information of China (English)
LI Ke-Ping
2006-01-01
In this paper, we propose a new cellular automaton model, which is based on NaSch traffic model. In our method, when a car has a larger velocity, if the gap between the car and its leading car is not enough large, it will decrease. The aim is that the following car has a buffer space to decrease its velocity at the next time, and then avoid to decelerate too high. The simulation results show that using our model, the car deceleration is realistic, and is closer to thefield measure than that of NaSch model.
Toward an automaton Constraint for Local Search
Directory of Open Access Journals (Sweden)
Jun He
2009-10-01
Full Text Available We explore the idea of using finite automata to implement new constraints for local search (this is already a successful technique in constraint-based global search. We show how it is possible to maintain incrementally the violations of a constraint and its decision variables from an automaton that describes a ground checker for that constraint. We establish the practicality of our approach idea on real-life personnel rostering problems, and show that it is competitive with the approach of [Pralong, 2007].
Numerical simulation of Mach reflection of cellular detonations
Li, J.; Lee, J. H. S.
2016-09-01
The Mach reflection of cellular detonation waves on a wedge is investigated numerically in an attempt to elucidate the effect of cellular instabilities on Mach reflection, the dependence of self-similarity on the thickness of a detonation wave, and the initial development of the Mach stem near the wedge apex. A two-step chain-branching reaction model is used to give a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. A sufficiently large distance of travel of the Mach stem is computed to observe the asymptotic behavior in the far field. Depending on the scale at which the Mach reflection process occurs, it is found that the Mach reflection of a cellular detonation behaves essentially in the same way as a planar ZND detonation wave. The cellular instabilities, however, cause the triple-point trajectory to fluctuate. The fluctuations are due to interactions of the triple point of the Mach stem with the transverse waves of cellular instabilities. In the vicinity of the wedge apex, the Mach reflection is found to be self-similar and corresponds to that of a shock wave of the same strength, since the Mach stem is highly overdriven initially. In the far field, the triple-point trajectory approaches a straight line, indicating that the Mach reflection becomes self-similar asymptotically. The distance of the approach to self-similarity is found to decrease rapidly with decreasing thickness of the detonation front.
Numerical simulation of Mach reflection of cellular detonations
Li, J.; Lee, J. H. S.
2016-07-01
The Mach reflection of cellular detonation waves on a wedge is investigated numerically in an attempt to elucidate the effect of cellular instabilities on Mach reflection, the dependence of self-similarity on the thickness of a detonation wave, and the initial development of the Mach stem near the wedge apex. A two-step chain-branching reaction model is used to give a thermally neutral induction zone followed by a chemical reaction zone for the detonation wave. A sufficiently large distance of travel of the Mach stem is computed to observe the asymptotic behavior in the far field. Depending on the scale at which the Mach reflection process occurs, it is found that the Mach reflection of a cellular detonation behaves essentially in the same way as a planar ZND detonation wave. The cellular instabilities, however, cause the triple-point trajectory to fluctuate. The fluctuations are due to interactions of the triple point of the Mach stem with the transverse waves of cellular instabilities. In the vicinity of the wedge apex, the Mach reflection is found to be self-similar and corresponds to that of a shock wave of the same strength, since the Mach stem is highly overdriven initially. In the far field, the triple-point trajectory approaches a straight line, indicating that the Mach reflection becomes self-similar asymptotically. The distance of the approach to self-similarity is found to decrease rapidly with decreasing thickness of the detonation front.
NUMERICAL SIMULATION OF CELLULAR/DENDRITIC PRIMARY SPACING
Institute of Scientific and Technical Information of China (English)
W．Q．Zhang; L．Xiao
2004-01-01
A numerical model has been established to calculate the primary spacing of cellular or dendritic structure with fluid flow considered. The computing results show that the primary spacing depends on the growing velocity, the temperature gradient on the interface and fluid flow. There is a critical growing velocity for the cell-dendrite transition, which has a relationship with the temperature gradient: Rcr=(3-4)×10-9GT. Fluid flow leads to an increase of the primary spacing for dendritic growth but a decrease for cellular growth,resulting in an instability on the interface.
Simulating Quantitative Cellular Responses Using Asynchronous Threshold Boolean Network Ensembles
With increasing knowledge about the potential mechanisms underlying cellular functions, it is becoming feasible to predict the response of biological systems to genetic and environmental perturbations. Due to the lack of homogeneity in living tissues it is difficult to estimate t...
Cellular and Porous Materials Thermal Properties Simulation and Prediction
Öchsner, Andreas; de Lemos, Marcelo J S
2008-01-01
Providing the reader with a solid understanding of the fundamentals as well as an awareness of recent advances in properties and applications of cellular and porous materials, this handbook and ready reference covers all important analytical and numerical methods for characterizing and predicting thermal properties. In so doing it directly addresses the special characteristics of foam-like and hole-riddled materials, combining theoretical and experimental aspects for characterization purposes.
Accelerating cellular automata simulations using AVX and CUDA
Szkoda, Sebastian; Tykierko, Mateusz
2012-01-01
We investigated various methods of parallelization of the Frish-Hasslacher-Pomeau (FHP) cellular automata algorithm for modeling fluid flow. These methods include SSE, AVX, and POSIX Threads for central processing units (CPUs) and CUDA for graphics processing units (GPUs). We present implementation details of the FHP algorithm based on AVX/SSE and CUDA technologies. We found that (a) using AVX or SSE is necessary to fully utilize the potential of modern CPUs; (b) CPUs and GPUs are comparable in terms of computational and economic efficiency only if the CPU code uses AVX or SSE instructions; (c) AVX does not offer any substantial improvement relative to SSE.
Cellular automata for traffic flow simulation with safety embedded notions
Larraga, M. E.; Alvarez-Icaza, L.
2007-01-01
In this paper a cellular automata model for one-lane traffic flow is presented. A new set of rules is proposed to better capture driver reactions to traffic that are intended to preserve safety on the highway. As a result, drivers behavior is derived from an analysis that determines the most appropriate action for a vehicle based on the distance from the vehicle ahead of it and the velocities of the two neighbor vehicles. The model preserves simplicity of CA rules and at the same time makes t...
Recursive definition of global cellular-automata mappings
DEFF Research Database (Denmark)
Feldberg, Rasmus; Knudsen, Carsten; Rasmussen, Steen
1994-01-01
A method for a recursive definition of global cellular-automata mappings is presented. The method is based on a graphical representation of global cellular-automata mappings. For a given cellular-automaton rule the recursive algorithm defines the change of the global cellular-automaton mapping...... as the number of lattice sites is incremented. A proof of lattice size invariance of global cellular-automata mappings is derived from an approximation to the exact recursive definition. The recursive definitions are applied to calculate the fractal dimension of the set of reachable states and of the set...
The Research of Image Encryption Algorithm Based on Chaos Cellular Automata
Shuiping Zhang; Huijune Luo
2012-01-01
The Research presents an image encryption algorithm which bases on chaotic cellular automata. This algorithm makes use of features that extreme sensitivity of chaotic system to initial conditions, the cellular automaton with a high degree of parallel processing. The encryption algorithm uses two-dimensional chaotic system to Encrypt image, Then establish a cellular automaton model on the initial encrypted image. Encryption key of this algorithm is made up of the initial value by the two-dimen...
Simulation Modeling by Classification of Problems: A Case of Cellular Manufacturing
Afiqah, K. N.; Mahayuddin, Z. R.
2016-02-01
Cellular manufacturing provides good solution approach to manufacturing area by applying Group Technology concept. The evolution of cellular manufacturing can enhance performance of the cell and to increase the quality of the product manufactured but it triggers other problem. Generally, this paper highlights factors and problems which emerge commonly in cellular manufacturing. The aim of the research is to develop a thorough understanding of common problems in cellular manufacturing. A part from that, in order to find a solution to the problems exist using simulation technique, this classification framework is very useful to be adapted during model building. Biology evolution tool was used in the research in order to classify the problems emerge. The result reveals 22 problems and 25 factors using cladistic technique. In this research, the expected result is the cladogram established based on the problems in cellular manufacturing gathered.
Combining cellular automata and Monte Carlo algorithm to simulate three-dimensional grain growth
Institute of Scientific and Technical Information of China (English)
WANG Wei; CHEN Ju-hua; GUO Pei-quan; ZHAO Ping
2006-01-01
A 3-D simulation of grain growth was conducted by utilizing cellular automata (CA) and Monte Carlo (MC) algorithm. In the simulating procedure, the three-dimensional space is divided into a large number of 2-D isometric planes. Then, each of the planes is divided into identical square cells. Finally, the cellular automata and Monte Carlo algorithm are combined together to simulate the grain growth. Through an evolutionary simulation, the recrystallized microstructure, the grain growth rate and the grain size distribution are acceptably predicted. The simulation routine can be used to simulate the real physical-metallurgy processes and to predict quantitative dynamic information of the evolution of microstructure. Further more, the method is also useful for optimization of materials properties by controlling the microstructure evolution.
Application of cellular automata approach for cloud simulation and rendering
Energy Technology Data Exchange (ETDEWEB)
Christopher Immanuel, W. [Department of Physics, Vel Tech High Tech Dr. Rangarajan Dr. Sakunthala Engineering College, Tamil Nadu, Chennai 600 062 (India); Paul Mary Deborrah, S. [Research Department of Physics, The American College, Tamil Nadu, Madurai 625 002 (India); Samuel Selvaraj, R. [Research Department of Physics, Presidency College, Tamil Nadu, Chennai 600 005 (India)
2014-03-15
Current techniques for creating clouds in games and other real time applications produce static, homogenous clouds. These clouds, while viable for real time applications, do not exhibit an organic feel that clouds in nature exhibit. These clouds, when viewed over a time period, were able to deform their initial shape and move in a more organic and dynamic way. With cloud shape technology we should be able in the future to extend to create even more cloud shapes in real time with more forces. Clouds are an essential part of any computer model of a landscape or an animation of an outdoor scene. A realistic animation of clouds is also important for creating scenes for flight simulators, movies, games, and other. Our goal was to create a realistic animation of clouds.
Application of cellular automata approach for cloud simulation and rendering
Christopher Immanuel, W.; Paul Mary Deborrah, S.; Samuel Selvaraj, R.
2014-03-01
Current techniques for creating clouds in games and other real time applications produce static, homogenous clouds. These clouds, while viable for real time applications, do not exhibit an organic feel that clouds in nature exhibit. These clouds, when viewed over a time period, were able to deform their initial shape and move in a more organic and dynamic way. With cloud shape technology we should be able in the future to extend to create even more cloud shapes in real time with more forces. Clouds are an essential part of any computer model of a landscape or an animation of an outdoor scene. A realistic animation of clouds is also important for creating scenes for flight simulators, movies, games, and other. Our goal was to create a realistic animation of clouds.
Macromolecular Chain at a Cellular Surface: a Computer Simulation Model
Xie, Jun; Pandey, Ras
2001-06-01
Computer simulations are performed to study conformation and dynamics of relatively large chain macromolecule at the surface of a model cell membrane - a preliminary attempt to ultimately realistic model for protein on a cell membrane. We use a discrete lattice of size Lx × L × L. The chain molecule of length Lc is modelled by consecutive nodes connected by bonds on the trail of a random walk with appropriate constraints such as excluded volume, energy dependent configurational bias, etc. Monte Carlo method is used to move chains via segmental dynamics, i.e., end-move, kink-jump, crank-shaft, reptation, etc. Membrane substrate is designed by an ensemble of short chains on a flat surface. Large chain molecule is then driven toward the membrane by a field. We plan to examine the dynamics of chain macromolecule, spread of its density, and its conformation.
Experimental investigations and numerical simulations of notch effect in cellular plastic materials
Marsavina, L.; Linul, E.; Voiconi, T.; Negru, R.
2016-04-01
Cellular plastics are light weight structures with many applications in civil, aeronautical, automotive and mechanical engineering. Properties of cellular materials depend on the properties of the solid material, on the shape and dimensions of the cellular structure and on the relative density of the cellular material. Most of cellular plastic materials are crushing in compression and have a brittle behavior in tension. The effect of notches represents an important issue in such materials, taking into account that for packing applications for example, notches/holes should be introduced in the cellular material. This paper investigates the effect of notches in compression for three different densities 100, 145 and 300 kg/m3 polyurethane (PUR) foams. Experimental investigations were performed on rectangular blocks of 100×100×25 mm with 16, 28 and 40 mm central holes. The mechanism of damage was monitored with an IR camera FLIR A40M. Purpose of the numerical simulations was to calibrate a material model, based on compression test for un-notched specimens using the CRUSHABLE FOAM models implemented in ABAQUS SIMULIA. Then the material models were used to simulate the experimental tests on notched blocks. Good agreement was obtained for the load - displacement curves obtained experimentally and from simulation. Also the plastic deformation patterns observed experimentally by IR thermograpghy were obtained numerically using the CRUSHABLE FOAM material model.
Institute of Scientific and Technical Information of China (English)
LI; Xia(黎夏); YEH; Gar-On(叶嘉安)
2002-01-01
This paper discusses the issues about the correlation of spatial variables during spatial decisionmaking using multicriteria evaluation (MCE) and cellular automata (CA). The correlation of spatial variables can cause the malfunction of MCE. In urban simulation, spatial factors often exhibit a high degree of correlation which is considered as an undesirable property for MCE. This study uses principal components analysis (PCA) to remove data redundancy among a large set of spatial variables and determine 'ideal points' for land development. PCA is integrated with cellular automata and geographical information systems (GIS) for the simulation of idealized urban forms for planning purposes.
Directory of Open Access Journals (Sweden)
Paulo Rangel Rios
2009-06-01
Full Text Available Microstructural evolution in three dimensions of nucleation and growth transformations is simulated by means of cellular automata (CA. In the simulation, nuclei are located in space according to a heterogeneous Poisson point processes. The simulation is compared with exact analytical solution recently obtained by Rios and Villa supposing that the intensity is a harmonic function of the spatial coordinate. The simulated data gives very good agreement with the analytical solution provided that the correct shape factor for the growing CA grains is used. This good agreement is auspicious because the analytical expressions were derived and thus are exact only if the shape of the growing regions is spherical.
Institute of Scientific and Technical Information of China (English)
LI Xin-zhong; GUO Jing-jie; SU Yan-qing; WU Shi-ping; FU Heng-zhi
2005-01-01
A phase-field model whose free energy of the solidification system derived from the Calphad thermodynamic modeling of phase diagram was used to simulate formation of cellular dendrites and fine cellular structures of Ti56Al44 alloy during directional solidification at high growth velocities. The liquid-solid phase transition of L→β was chosen. The dynamics of breakdown of initially planar interfaces into cellular dendrites and fine cellular structures were shown firstly at two growth velocities. Then the unidirectional free growths of two initial nucleations evolving to fine cellular dendrites were investigated. The tip splitting phenomenon is observed and the negative temperature gradient in the liquid represents its supercooling directional solidification. The simulation results show the realistic evolution of interfaces and microstructures and they agree with experimental one.
A cellular automata model for simulating fed-batch penicillin fermentation process
Institute of Scientific and Technical Information of China (English)
Yu Naigong; Ruan Xiaogang
2006-01-01
A cellular automata model to simulate penicillin fed-batch fermentation process(CAPFM)was established in this study,based on a morphologically structured dynamic penicillin production model,that is in turn based on the growth mechanism of penicillin producing microorganisms and the characteristics of penicillin fed-batch fermentation.CAPFM uses the three-dimensional cellular automata as a growth space,and a Moore-type neighborhood as the cellular neighborhood.The transition roles of CAPFM are designed based on mechanical and structural kinetic models of penicillin batch-fed fermentation processes.Every cell of CAPFM represents a single or specific number of penicillin producing microorganisms,and has various state.The simulation experimental results show that CAPFM replicates the evolutionary behavior of penicillin batch-fed fermentation processes described by the structured penicillin production kinetic model accordingly.
Blázquez, J.S.; Conde, C. F.; Conde, A.
2011-01-01
Cellular automata simulations have been performed to simulate the crystallization process under a limited growth approximation. This approximation resembles several characteristics exhibited by nanocrystalline microstructures and nanocrystallization kinetics. Avrami exponent decreases from a value n = 4 indicating interface controlled growth and constant nucleation rate to a value n ~ 1 indicating absence of growth. A continuous change of the growth contribution to the Avrami exponent from ze...
A federation of simulations based on cellular automata in cyber-physical systems
Directory of Open Access Journals (Sweden)
Hoang Van Tran
2016-02-01
Full Text Available In cyber-physical system (CPS, cooperation between a variety of computational and physical elements usually poses difficulties to current modelling and simulation tools. Although much research has proposed to address those challenges, most solutions do not completely cover uncertain interactions in CPS. In this paper, we present a new approach to federate simulations for CPS. A federation is a combination of, and coordination between simulations upon a standard of communication. In addition, a mixed simulation is defined as several parallel simulations federated in a common time progress. Such simulations run on the models of physical systems, which are built based on cellular automata theory. The experimental results are performed on a federation of three simulations of forest fire spread, river pollution diffusion and wireless sensor network. The obtained results can be utilized to observe and predict the behaviours of physical systems in their interactions.
Automaton based detection of affected cells in three dimensional biological system
Dundas, Jitesh
2011-01-01
The aim of this research review is to propose the logic and search mechanism for the development of an artificially intelligent automaton (AIA) that can find affected cells in a 3-dimensional biological system. Research on the possible application of such automatons to detect and control cancer cells in the human body are greatly focused MRI and PET scans finds the affected regions at the tissue level even as we can find the affected regions at the cellular level using the framework. The AIA may be designed to ensure optimum utilization as they record and might control the presence of affected cells in a human body. The proposed models and techniques can be generalized and used in any application where cells are injured or affected by some disease or accident. The best method to import AIA into the body without surgery or injection is to insert small pill like automata, carrying material viz drugs or leukocytes that is needed to correct the infection. In this process, the AIA can be compared to nano pills to ...
A coarse-grained model for the simulations of biomolecular interactions in cellular environments
Energy Technology Data Exchange (ETDEWEB)
Xie, Zhong-Ru; Chen, Jiawen; Wu, Yinghao, E-mail: yinghao.wu@einstein.yu.edu [Department of Systems and Computational Biology, Albert Einstein College of Medicine of Yeshiva University, 1300 Morris Park Avenue, Bronx, New York 10461 (United States)
2014-02-07
The interactions of bio-molecules constitute the key steps of cellular functions. However, in vivo binding properties differ significantly from their in vitro measurements due to the heterogeneity of cellular environments. Here we introduce a coarse-grained model based on rigid-body representation to study how factors such as cellular crowding and membrane confinement affect molecular binding. The macroscopic parameters such as the equilibrium constant and the kinetic rate constant are calibrated by adjusting the microscopic coefficients used in the numerical simulations. By changing these model parameters that are experimentally approachable, we are able to study the kinetic and thermodynamic properties of molecular binding, as well as the effects caused by specific cellular environments. We investigate the volumetric effects of crowded intracellular space on bio-molecular diffusion and diffusion-limited reactions. Furthermore, the binding constants of membrane proteins are currently difficult to measure. We provide quantitative estimations about how the binding of membrane proteins deviates from soluble proteins under different degrees of membrane confinements. The simulation results provide biological insights to the functions of membrane receptors on cell surfaces. Overall, our studies establish a connection between the details of molecular interactions and the heterogeneity of cellular environments.
Idealized Mesoscale Model Simulations of Open Cellular Convection Over the Sea
DEFF Research Database (Denmark)
Vincent, Claire Louise; Hahmann, Andrea N.; Kelly, Mark C.
2012-01-01
The atmospheric conditions during an observed case of open cellular convection over the North Sea were simulated using the Weather Research and Forecasting (WRF) numerical model. Wind, temperature and water vapour mixing ratio profiles from the WRF simulation were used to initialize an idealized...... version of the model, which excluded the effects of topography, surface inhomogeneities and large-scale weather forcing. Cells with an average diameter of 17.4 km developed. Simulations both with and without a capping inversion were made, and the cell-scale kinetic energy budget was calculated for each...
[Evaluation of Cellular Effects Caused by Lunar Regolith Simulant Including Fine Particles].
Horie, Masanori; Miki, Takeo; Honma, Yoshiyuki; Aoki, Shigeru; Morimoto, Yasuo
2015-06-01
The National Aeronautics and Space Administration has announced a plan to establish a manned colony on the surface of the moon, and our country, Japan, has declared its participation. The surface of the moon is covered with soil called lunar regolith, which includes fine particles. It is possible that humans will inhale lunar regolith if it is brought into the spaceship. Therefore, an evaluation of the pulmonary effects caused by lunar regolith is important for exploration of the moon. In the present study, we examine the cellular effects of lunar regolith simulant, whose components are similar to those of lunar regolith. We focused on the chemical component and particle size in particular. The regolith simulant was fractionated to effects of fine regolith simulant whose primary particle size is 5.10 μm. These regolith simulants were applied to human lung carcinoma A549 cells at concentrations of 0.1 and 1.0 mg/ml. Cytotoxicity, oxidative stress and immune response were examined after 24 h exposure. Cell membrane damage, mitochondrial dysfunction and induction of Interleukin-8 (IL-8) were observed at the concentration of 1.0 mg/ml. The cellular effects of the regolith simulant at the concentration of 0.1 mg/ml were small, as compared with crystalline silica as a positive control. Secretion of IL-1β and tumor necrosis factor-α (TNF-α) was observed at the concentration of 1.0 mg/ml, but induction of gene expression was not observed at 24 h after exposure. Induction of cellular oxidative stress was small. Although the cellular effects tended to be stronger in the effects of lunar regolith simulant such as cell membrane damage, induction of oxidative stress and proinflammatory effect.
Accountability Analysis of Electronic Commerce Protocols by Finite Automaton Model
Institute of Scientific and Technical Information of China (English)
Xie Xiao-yao; Zhang Huan-guo
2004-01-01
The accountability of electronic commerce protocols is an important aspect to insures security of electronic transaction. This paper proposes to use Finite Automaton (FA) model as a new kind of framework to analyze the trans action protocols in the application of electronic commerce.
Cryptanalysis on a finite automaton public key cryptosystem
Institute of Scientific and Technical Information of China (English)
戴大为; 吴逵; 张焕国
1996-01-01
An attack algorithm is proposed on a finite automaton public key cryptosystem.It is proved that this attack can break FAPKCO in polynomial time.The basic idea can be used in principle to attack other FAPKCs.Therefore,while designing an FAPKC,it must be taken into account whether it is secure or not under this kind of attack.
Oku, Makito; Aihara, Kazuyuki
2010-11-01
A modularly-structured neural network model is considered. Each module, which we call a ‘cell’, consists of two parts: a Hopfield neural network model and a multilayered perceptron. An array of such cells is used to simulate the Rule 110 cellular automaton with high accuracy even when all the units of neural networks are replaced by stochastic binary ones. We also find that noise not only degrades but also facilitates computation if the outputs of multilayered perceptrons are below the threshold required to update the states of the cells, which is a stochastic resonance in computation.
Statistical analysis of cellular detonation dynamics from numerical simulations: one-step chemistry
Sharpe, G. J.; Radulescu, M. I.
2011-10-01
In this paper, two methods are developed for statistically analysing the nonlinear cellular dynamics from numerical simulations of gaseous detonations, one use of which is the systematic determination of detonation cell sizes from such simulations. Both these methods rely on signed vorticity records in which the individual families of transverse waves are captured independently. The first method involves an automated extraction of the main triple-point tracks from the vorticity records, allowing statistical analysis of the spacings between neighbouring tracks. The second method uses the autocorrelation function to spectrally analyse the vorticity records. These methods are then employed for a preliminary analysis of the cellular dynamics of the standard, idealized one-step chemistry model. Evidence is found for 'cell size doubling' bifurcations in the one-step model as the cellular dynamics become more irregular (e.g. as the activation is increased). It is also shown that the statistical models converge slowly due to systematic 'shot-to-shot' variation in the cellular dynamics for fixed parameters with different initial perturbations. Instead, it appears that a range of equally probable cell sizes can be obtained for given parameters.
Simulating three-dimensional hydrodynamics on a cellular-automata machine
Adler, C; Margolus, N H; Rothman, D H; Adler, Christopher; Boghosian, Bruce M; Margolus, Norman; Rothman, Daniel H
1995-01-01
We demonstrate how three-dimensional fluid flow simulations can be carried out on the Cellular Automata Machine 8 (CAM-8), a special-purpose computer for cellular-automata computations. The principal algorithmic innovation is the use of a lattice-gas model with a 16-bit collision operator that is specially adapted to the machine architecture. It is shown how the collision rules can be optimized to obtain a low viscosity of the fluid. Predictions of the viscosity based on a Boltzmann approximation agree well with measurements of the viscosity made on CAM-8. Several test simulations of flows in simple geometries -- channels, pipes, and a cubic array of spheres -- are carried out. Measurements of average flux in these geometries compare well with theoretical predictions.
Strayer, D L; Johnston, W A
2001-11-01
Dual-task studies assessed the effects of cellular-phone conversations on performance of a simulated driving task. Performance was not disrupted by listening to radio broadcasts or listening to a book on tape. Nor was it disrupted by a continuous shadowing task using a handheld phone, ruling out, in this case, dual-task interpretations associated with holding the phone, listening, or speaking, However significant interference was observed in a word-generation variant of the shadowing task, and this deficit increased with the difficulty of driving. Moreover unconstrained conversations using either a handheld or a hands-free cell phone resulted in a twofold increase in the failure to detect simulated traffic signals and slower reactions to those signals that were detected. We suggest that cellular-phone use disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving. PMID:11760132
Mao, Jian; Guo, Ruohai; Yan, Li-Tang
2014-07-01
Clarifying the mechanisms of cellular interactions of graphene family nanomaterials is an urgent issue to the development of guidelines for safer biomedical applications and to the evaluation of health and environment impacts. By combining large-scale computer simulations, theoretical analysis, and experimental discussions, here we present a systematic study on the interactions of graphene nanosheets having various oxidization degrees with a model lipid bilayer membrane. In the mesoscopic simulations, we investigate the detailed translocation pathways of these materials across a 56 × 56 nm(2) membrane patch which allows us to fully consider the role of membrane perturbation during this process. A phase diagram regarding the transmembrane translocation mechanisms of graphene nanosheets is thereby obtained in the space of oxidization degree and particle size. Then, we propose a theoretical approach to analyze the effects of various initial equilibrium states of graphene nanosheets with membrane on their following cellular uptake process. Finally, we demonstrate that the simulation and theoretical results reproduce some important experimental findings towards the mechanisms of cytotoxicity and antibacterial activity of graphene materials. These results not only provide new insight into the cellular internalization mechanism of graphene-based nanomaterials but also offer fundamental understanding on their physicochemical properties which can be precisely tailored for safer biomedical and environment applications.
Modeling Mixed Traffic Flow at Crosswalks in Micro-Simulations Using Cellular Automata
Institute of Scientific and Technical Information of China (English)
DUAN Houli; ZHANG Yi
2007-01-01
The cellular automata (CA) micro-simulation model was used to describe the behavior of the mixed traffic flows at crosswalks where the pedestrians compete with the vehicles to cross the roadway. The focus of this paper is the behavior of pedestrians and the influence of pedestrians' behavior on the vehicle flow, pedestrian flows, and the vehicle waiting time. The proportion of pedestrians who do not obey traffic laws, the group effect, and expected waiting time of pedestrians, regarded as the most important pedestrian characteristics, are taken into consideration in the analysis. Simulation results show the ability of the microsimulation to capture the most important features of mixed traffic flow.
Czechowski, Zbigniew
2015-07-01
On the basis of simple cellular automaton, the microscopic mechanisms, which can be responsible for elongation of tails of cluster size distributions, were analyzed. It was shown that only the appropriate forms of rebound function can lead to inverse power tails if densities of the grid are small or moderate. For big densities, correlations between clusters become significant and lead to elongation of tails and flattening of the distribution to a straight line in log-log scale. The microscopic mechanism, given by the rebound function, included in simple 1D RDA can be projected on the geometric mechanism, which favours larger clusters in 2D RDA.
Directory of Open Access Journals (Sweden)
Ramoni Marco F
2007-05-01
Full Text Available Abstract Background Reverse engineering cellular networks is currently one of the most challenging problems in systems biology. Dynamic Bayesian networks (DBNs seem to be particularly suitable for inferring relationships between cellular variables from the analysis of time series measurements of mRNA or protein concentrations. As evaluating inference results on a real dataset is controversial, the use of simulated data has been proposed. However, DBN approaches that use continuous variables, thus avoiding the information loss associated with discretization, have not yet been extensively assessed, and most of the proposed approaches have dealt with linear Gaussian models. Results We propose a generalization of dynamic Gaussian networks to accommodate nonlinear dependencies between variables. As a benchmark dataset to test the new approach, we used data from a mathematical model of cell cycle control in budding yeast that realistically reproduces the complexity of a cellular system. We evaluated the ability of the networks to describe the dynamics of cellular systems and their precision in reconstructing the true underlying causal relationships between variables. We also tested the robustness of the results by analyzing the effect of noise on the data, and the impact of a different sampling time. Conclusion The results confirmed that DBNs with Gaussian models can be effectively exploited for a first level analysis of data from complex cellular systems. The inferred models are parsimonious and have a satisfying goodness of fit. Furthermore, the networks not only offer a phenomenological description of the dynamics of cellular systems, but are also able to suggest hypotheses concerning the causal interactions between variables. The proposed nonlinear generalization of Gaussian models yielded models characterized by a slightly lower goodness of fit than the linear model, but a better ability to recover the true underlying connections between
Cellular automata model based on GIS and urban sprawl dynamics simulation
Mu, Fengyun; Zhang, Zengxiang
2005-10-01
The simulation of land use change process needs the support of Geographical Information System (GIS) and other relative technologies. While the present commercial GIS lack capabilities of distribution, prediction, and simulation of spatial-temporal data. Cellular automata (CA) provide dynamically modeling "from bottom-to-top" framework and posses the capability of modeling spatial-temporal evolvement process of a complicated geographical system, which is composed of a fourfold: cells, states, neighbors and rules. The simplicity and flexibility make CA have the ability to simulate a variety of behaviors of complex systems. One of the most potentially useful applications of cellular automata from the point of view of spatial planning is their use in simulations of urban sprawl at local and regional level. The paper firstly introduces the principles and characters of the cellular automata, and then discusses three methods of the integration of CA and GIS. The paper analyses from a practical point of view the factors that effect urban activities in the science of spatial decision-making. The status of using CA to dynamic simulates of urban expansion at home and abroad is analyzed. Finally, the problems and tendencies that exist in the application of CA model are detailed discussed, such as the quality of the data that the CA needs, the self-organization of the CA roots in the mutual function among the elements of the system, the partition of the space scale, the time calibration of the CA and the integration of the CA with other modular such as artificial nerve net modular and population modular etc.
Simulation of annealing process effect on texture evolution of deep-drawing sheet St15
Institute of Scientific and Technical Information of China (English)
Jinghong Sun; Yazheng Liu; Leyu Zhou
2005-01-01
A two-dimensional cellular automaton method was used to simulate grain growth during the recrystallization annealing of deep-drawing sheet Stl5, taking the simulated result of recrystallization and the experimental result of the annealing texture of deepdrawing sheet St15 as the initial condition and reference. By means of computer simulation, the microstructures and textures of different periods of grain growth were predicted. It is achieved that the grain size, shape and texture become stable after the grain growth at a constant temperature of 700℃ for 10 h, and the advantaged texture components { 111 } and { 111 } are dominant.
Dendritic grain growth simulation in weld pool of nickel base alloy
Institute of Scientific and Technical Information of China (English)
Zhan Xiaohong; Wei Yanhong; Ma Rui; Dong Zhibo
2008-01-01
Dendritic grain growth at the edge of the weld pool is simulated using a stochastic numerical model of cellular automaton algorithm. The grain growth model is established based upon the balance of solute in the solid/liquid interface of the dendrite tip. Considering the complicated nucleation condition and competitive growth, the dendrite morphologies of different nucleation condition are simulated. The simulated results reproduced the dendrite grain evolution process at the edge of the weld pool. It is indicated that the nucleation condition is an important factor influencing the grain morphologies especially the morphologies of secondary and tertiary arms.
Pavlou, L.; Georgoudas, I. G.; Sirakoulis, G. Ch.; Scordilis, E. M.; Andreadis, I.
This paper presents an extensive simulation tool based on a Cellular Automata (CA) system that models fundamental seismic characteristics of a region. The CA-based dynamic model consists of cells-charges and it is used for the simulation of the earthquake process. The simulation tool has remarkably accelerated the response of the model by incorporating principles of the High Performance Computing (HPC). Extensive programming features of parallel computing have been applied, thus improving its processing effectiveness. The tool implements an enhanced (or hyper-) 2-dimensional version of the proposed CA model. Regional characteristics that depend on the seismic background of the area under study are assigned to the model with the application of a user-friendly software environment. The model is evaluated with real data that correspond to a circular region around Skyros Island, Greece, for different time periods, as for example one of 45 years (1901-1945). The enhanced 2-dimensional version of the model incorporates all principal characteristics of the 2-dimensional one, also including groups of CA cells that interact with others, located to a considerable distance in an attempt to simulate long-range interaction. The advanced simulation tool has been thoroughly evaluated. Several measurements have been made for different critical states, as well as for various cascade (earthquake) sizes, cell activities and different neighbourhood sizes. Simulation results qualitatively approach the Gutenberg-Richter (GR) scaling law and reveal fundamental characteristics of the system.
A Vector-based Cellular Automata Model for Simulating Urban Land Use Change
Institute of Scientific and Technical Information of China (English)
LU Yi; CAO Min; ZHANG Lei
2015-01-01
Cellular Automata (CA) is widely used for the simulation of land use changes.This study applied a vector-based CA model to simulate land use change in order to minimize or eliminate the scale sensitivity in traditional raster-based CA model.The cells of vector-based CA model are presented according to the shapes and attributes of geographic entities,and the transition rules of vector-based CA model are improved by taking spatial variables of the study area into consideration.The vector-based CA model is applied to simulate land use changes in downtown of Qidong City,Jiangsu Province,China and its validation is confirmed by the methods of visual assessment and spatial accuracy.The simulation result of vector-based CA model reveals that nearly 75％ of newly increased urban cells are located in the northwest and southwest parts of the study area from 2002 to 2007,which is in consistent with real land use map.In addition,the simulation results of the vector-based and raster-based CA models are compared to real land use data and their spatial accuracies are found to be 84.0％ and 81.9％,respectively.In conclusion,results from this study indicate that the vector-based CA model is a practical and applicable method for the simulation of urbanization processes.
A Multitarget Land Use Change Simulation Model Based on Cellular Automata and Its Application
Directory of Open Access Journals (Sweden)
Jun Yang
2014-01-01
Full Text Available Based on the analysis of the existing land use change simulation model, combined with macroland use change driving factors and microlocal land use competition, and through the application of Python language integrated technical approaches such as CA, GIS, AHP, and Markov, a multitarget land use change simulation model based on cellular automata(CA is established. This model was applied to conduct scenario simulation of land use/cover change of the Jinzhou New District, based on 1:10000 map scale land use, planning, topography, statistics, and other data collected in the year of 1988, 2003, and 2012. The simulation results indicate the following: (1 this model can simulate the mutual transformation of multiple land use types in a relatively satisfactory way; it takes land use system as a whole and simultaneously takes the land use demand in the macrolevel and the land use suitability in the local scale into account; and (2 the simulation accuracy of the model reaches 72%, presenting higher creditability. The model is capable of providing auxiliary decision-making support for coastal regions with the analysis of the land use change driving mechanism, prediction of land use change tendencies, and establishment of land resource sustainable utilization policies.
Institute of Scientific and Technical Information of China (English)
Jia Ning; Ma Shou-Feng; Zhong Shi-Quan
2012-01-01
Previous studies suggest that there are three different jam phases in the cellular automata automaton model with a slow-to-start rule under open boundaries.In the present paper,the dynamics of each free-flow-jam phase transition is studied.By analysing the microscopic behaviour of the traffic flow,we obtain analytical results on the phase transition dynamics.Our results can describe the detailed time evolution of the system during phase transition,while they provide good approximation for the numerical simulation data.These findings can perfectly explain the microscopic mechanism and details of the boundary-triggered phase transition dynamics.
Hickmott, Curtis W.
Cellular core tooling is a new technology which has the capability to manufacture complex integrated monolithic composite structures. This novel tooling method utilizes thermoplastic cellular cores as inner tooling. The semi-rigid nature of the cellular cores makes them convenient for lay-up, and under autoclave temperature and pressure they soften and expand providing uniform compaction on all surfaces including internal features such as ribs and spar tubes. This process has the capability of developing fully optimized aerospace structures by reducing or eliminating assembly using fasteners or bonded joints. The technology is studied in the context of evaluating its capabilities, advantages, and limitations in developing high quality structures. The complex nature of these parts has led to development of a model using the Finite Element Analysis (FEA) software Abaqus and the plug-in COMPRO Common Component Architecture (CCA) provided by Convergent Manufacturing Technologies. This model utilizes a "virtual autoclave" technique to simulate temperature profiles, resin flow paths, and ultimately deformation from residual stress. A model has been developed simulating the temperature profile during curing of composite parts made with the cellular core technology. While modeling of composites has been performed in the past, this project will look to take this existing knowledge and apply it to this new manufacturing method capable of building more complex parts and develop a model designed specifically for building large, complex components with a high degree of accuracy. The model development has been carried out in conjunction with experimental validation. A double box beam structure was chosen for analysis to determine the effects of the technology on internal ribs and joints. Double box beams were manufactured and sectioned into T-joints for characterization. Mechanical behavior of T-joints was performed using the T-joint pull-off test and compared to traditional
Genetic algorithms for determining the parameters of cellular automata in urban simulation
Institute of Scientific and Technical Information of China (English)
LI; Xia; YANG; QingSheng; LIU; XiaoPing
2007-01-01
This paper demonstrates that cellular automata (CA) can be a useful tool for analyzing the process of many geographical phenomena. There are many studies on using CA to simulate the evolution of cites. Urban dynamics is determined by many spatial variables. The contribution of each spatial variable to the simulation is quantified by its parameter or weight. Calibration procedures are usually required for obtaining a suitable set of parameters so that the realistic urban forms can be simulated. Each parameter has a unique role in controlling urban morphology in the simulation. In this paper, these parameters for urban simulation are determined by using empirical data. Genetic algorithms are used to search for the optimal combination of these parameters. There are spatial variations for urban dynamics in a large region. Distinct sets of parameters can be used to represent the unique features of urban dynamics for various subregions. A further experiment is to evaluate each set of parameters based on the theories of compact cities. It is considered that the better set of parameters can be identified according to the utility function in terms of compact development. This set of parameters can be cloned to other regions to improve overall urban morphology. The original parameters can be also modified to produce more compact urban forms for planning purposes. This approach can provide a useful exploratory tool for testing various planning scenarios for urban development.
Chen, Qingcai; Shi, Jianghong; Liu, Xiaowei; Wu, Wei; Liu, Bo; Zhang, Hui
2013-03-01
A cellular automata model (CA model) was used to simulate the soil column leaching process of estrogens during the processes of migration and transformation. The results of the simulated leaching experiment showed that the first-order degradation rates of 17α-ethynylestradiol (EE2), 17β-estradiol (E2) and estrone (E1) were 0.131 h- 1 for E2, 0.099 h- 1 for E1 and 0.064 h- 1 for EE2 in the EE2 and E2 leaching process, and the first-order sorption rates were 5.94 h- 1 for E2, 5.63 h- 1 for EE2, 3.125 h- 1 for E1. Their sorption rates were positively correlated with the n-octanol/water partition coefficients. When the diffusion rate was low, its impact on the simulation results was insignificant. The increase in sorption and degradation rates caused the decrease in the total estrogens that leached. In addition, increasing the sorption rate could delay the emerging time of the maximum concentration of estrogen that leached, whereas increasing the degradation rate could shorten the emerging time of the maximum concentration of estrogen that leached. The comparison made between the experimental data and the simulation results of the CA model and the HYDRUS-1D software showed that the establishment of one-component and multi-component CA models could simulate EE2 and E2 soil column leaching processes, and the CA models achieve an intuitive, dynamic, and visual simulation.
Stone, John E.; Hallock, Michael J.; Phillips, James C.; Peterson, Joseph R.; Luthey-Schulten, Zaida; Schulten, Klaus
2016-01-01
Many of the continuing scientific advances achieved through computational biology are predicated on the availability of ongoing increases in computational power required for detailed simulation and analysis of cellular processes on biologically-relevant timescales. A critical challenge facing the development of future exascale supercomputer systems is the development of new computing hardware and associated scientific applications that dramatically improve upon the energy efficiency of existing solutions, while providing increased simulation, analysis, and visualization performance. Mobile computing platforms have recently become powerful enough to support interactive molecular visualization tasks that were previously only possible on laptops and workstations, creating future opportunities for their convenient use for meetings, remote collaboration, and as head mounted displays for immersive stereoscopic viewing. We describe early experiences adapting several biomolecular simulation and analysis applications for emerging heterogeneous computing platforms that combine power-efficient system-on-chip multi-core CPUs with high-performance massively parallel GPUs. We present low-cost power monitoring instrumentation that provides sufficient temporal resolution to evaluate the power consumption of individual CPU algorithms and GPU kernels. We compare the performance and energy efficiency of scientific applications running on emerging platforms with results obtained on traditional platforms, identify hardware and algorithmic performance bottlenecks that affect the usability of these platforms, and describe avenues for improving both the hardware and applications in pursuit of the needs of molecular modeling tasks on mobile devices and future exascale computers.
Institute of Scientific and Technical Information of China (English)
吴义虎; 李意芬; 喻伟; 喻丹
2014-01-01
The behavior of the driver was considered as the rule of the driver change of lanes,and the new rule of the changes of lanes with the combination between the driver behavior and the coincidental traffic was put forward,then a improved cellular automa-ton model was put forward,the model was proposed to describe the characteristics of co-incidental traffic j ams.By the proposed model,the velocity of traffic flow and the length of vehicle lines by coincidental traffic j ams was simulated,and the results of the simula-tion was proposed.%以元胞自动机模型为基础，在传统的车辆换道规则上，引入驾驶人行为因素，根据不同区域交通流特点和驾驶行为特点，给出了不同的车辆换道规则，建立了一种适用于城市道路偶发性拥堵交通流行为分析的元胞自动机改进模型。并利用该模型，模拟分析了偶发性拥堵发生时不同车流密度的车辆排队和平均车速情况。
Energy Technology Data Exchange (ETDEWEB)
Beznosyuk, S.A. [Department of Physical Chemistry, Altai State University, 61, Lenin Av., 656049, Barnaul (Russian Federation)], E-mail: bsa1953@mail.ru; Lerh, Y.V.; Zhukovsky, T.M.; Zhukovsky, M.S. [Department of Physical Chemistry, Altai State University, 61, Lenin Av., 656049, Barnaul (Russian Federation)
2007-09-15
Computer simulation of self-assembly growth of fractal nanodendrites is suggested by using a new model of multi-directed cellular automatic device. The novelty is that in a framework of the multiparticle diffusion limited aggregation (DLA) model, atoms stick to the growing cluster according to specific kinematics multi-directional contact bonds. The aggregation is limited by initial concentration of particles confined inside definite nano-sized enclosures. Self-organizing process results in the formation of fractal dendrite nanostructures. From results of computer experiments, some equations for cluster fractal dimension D, depending on the initial concentration C of diffusing particles in 2d and 3d space enclosures, are deduced. Correlations between cluster fractal dimension D and number of aggregated particles N are found also.
Modeling and Simulation for Urban Rail Traffic Problem Based on Cellular Automata
Institute of Scientific and Technical Information of China (English)
许琰; 曹成铉; 李明华; 罗金龙
2012-01-01
Based on the Nagel-Schreckenberg model, we propose a new cellular automata model to simulate the urban rail traffic flow under moving block system and present a new minimum instantaneous distance formula under pure moving block. We also analyze the characteristics of the urban rail traffic flow under the influence of train density, station dwell times, the length of train, and the train velocity. Train delays can be decreased effectively through flexible departure intervals according to the preceding train type before its departure. The results demonstrate that a suitable adjustment of the current train velocity based on the following train velocity can greatly shorten the minimum departure intervals and then increase the capacity of rail transit.
Electroacoustic simulation and experiment on a miniature loudspeaker for cellular phones
Huang, Jin H.; Her, Hong-Ching; Shiah, Y. C.; Shin, Shaw-Jyh
2008-02-01
The performance of a miniature loudspeaker used in computer, communication, and consumer electronics products is an integrated function with coupled magnetic, electrical, mechanical, and acoustical fields. Through the finite element method, optimal design parameters to enhance the performance of a miniature loudspeaker are obtained. The sound pressure response of the miniature loudspeaker is simulated by using an equivalent circuit method. Its electrical driver, mechanical motion, and acoustical radiation are analogized by their equivalent elements individually. For the present work, such an analysis is carried out for a miniature loudspeaker manufactured in the cellular phone industry. All speaker parameters in the analysis are experimentally measured. Sound pressure responses are experimentally taken by PULSE Electroacoustics in an anechoic chamber. The equivalent-circuit analysis show fairly good agreement with the experimental results.
Stability of Cellular Automata Trajectories Revisited: Branching Walks and Lyapunov Profiles
Baetens, Jan M.; Gravner, Janko
2016-10-01
We study non-equilibrium defect accumulation dynamics on a cellular automaton trajectory: a branching walk process in which a defect creates a successor on any neighborhood site whose update it affects. On an infinite lattice, defects accumulate at different exponential rates in different directions, giving rise to the Lyapunov profile. This profile quantifies instability of a cellular automaton evolution and is connected to the theory of large deviations. We rigorously and empirically study Lyapunov profiles generated from random initial states. We also introduce explicit and computationally feasible variational methods to compute the Lyapunov profiles for periodic configurations, thus developing an analog of Floquet theory for cellular automata.
Simulating debris flows through a hexagonal cellular automata model: SCIDDICA S3–hex
Directory of Open Access Journals (Sweden)
D. D’Ambrosio
2003-01-01
Full Text Available Cellular Automata (CA represent a formal frame for dynamical systems, which evolve on the base of local interactions. Some types of landslide, such as debris flows, match well this requirement. The latest hexagonal release (S3–hex of the deterministic model SCIDDICA, specifically developed for simulating debris flows, is described. For CA simulation purposes, landslides can be viewed as a dynamical system, subdivided into elementary parts, whose state evolves exclusively as a consequence of local interactions within a spatial and temporal discretum. Space is the world of the CA, here constituted by hexagonal cells. The attributes of each cell ("substates" describe physical characteristics. For computational reasons, the natural phenomenon is "decomposed" into a number of elementary processes, whose proper composition makes up the "transition function" of the CA. By simultaneously applying this function to all the cells, the evolution of the phenomenon can be simulated in terms of modifications of the substates. SCIDDICA S3–hex exhibits a great flexibility in modelling debris flows. With respect to the previous releases of the model, the mechanism of progressive erosion of the soil cover has been added to the transition function. Considered substates are: altitude; thickness and energy of landslide debris; depth of erodable soil cover; debris outflows. Considered elementary processes are: mobilisation triggering and effect (T1, debris outflows (I1, update of landslide debris thickness and energy (I2, and energy loss (T2. Simulations of real debris flows, occurred in Campania (Southern Italy in May 1998 (Sarno and December 1999 (San Martino V.C. and Cervinara, have been performed for model calibration purposes; some examples of analysis are briefly described. Possible applications of the method are: risk mapping, also based on a statistical approach; evaluating the effects of mitigation actions (e.g. stream deviations, topographic
High resolution simulations of energy absorption in dynamically loaded cellular structures
Winter, R. E.; Cotton, M.; Harris, E. J.; Eakins, D. E.; McShane, G.
2016-04-01
Cellular materials have potential application as absorbers of energy generated by high velocity impact. CTH, a Sandia National Laboratories Code which allows very severe strains to be simulated, has been used to perform very high resolution simulations showing the dynamic crushing of a series of two-dimensional, stainless steel metal structures with varying architectures. The structures are positioned to provide a cushion between a solid stainless steel flyer plate with velocities ranging from 300 to 900 m/s, and an initially stationary stainless steel target. Each of the alternative architectures under consideration was formed by an array of identical cells each of which had a constant volume and a constant density. The resolution of the simulations was maximised by choosing a configuration in which one-dimensional conditions persisted for the full period over which the specimen densified, a condition which is most readily met by impacting high density specimens at high velocity. It was found that the total plastic flow and, therefore, the irreversible energy dissipated in the fully densified energy absorbing cell, increase (a) as the structure becomes more rodlike and less platelike and (b) as the impact velocity increases. Sequential CTH images of the deformation processes show that the flow of the cell material may be broadly divided into macroscopic flow perpendicular to the compression direction and jetting-type processes (microkinetic flow) which tend to predominate in rod and rodlike configurations and also tend to play an increasing role at increased strain rates. A very simple analysis of a configuration in which a solid flyer impacts a solid target provides a baseline against which to compare and explain features seen in the simulations. The work provides a basis for the development of energy absorbing structures for application in the 200-1000 m/s impact regime.
Speech intelligibility measure for vocal control of an automaton
Naranjo, Michel; Tsirigotis, Georgios
1998-07-01
The acceleration of investigations in Speech Recognition allows to augur, in the next future, a wide establishment of Vocal Control Systems in the production units. The communication between a human and a machine necessitates technical devices that emit, or are submitted to important noise perturbations. The vocal interface introduces a new control problem of a deterministic automaton using uncertain information. The purpose is to place exactly the automaton in a final state, ordered by voice, from an unknown initial state. The whole Speech Processing procedure, presented in this paper, has for input the temporal speech signal of a word and for output a recognised word labelled with an intelligibility index given by the recognition quality. In the first part, we present the essential psychoacoustic concepts for the automatic calculation of the loudness of a speech signal. The architecture of a Time Delay Neural Network is presented in second part where we also give the results of the recognition. The theory of the fuzzy subset, in third part, allows to extract at the same time a recognised word and its intelligibility index. In the fourth part, an Anticipatory System models the control of a Sequential Machine. A prediction phase and an updating one appear which involve data coming from the information system. A Bayesian decision strategy is used and the criterion is a weighted sum of criteria defined from information, minimum path functions and speech intelligibility measure.
Liu, D. R.; Mangelinck-Noël, N.; Gandin, Ch-A.; Zimmermann, G.; Sturz, L.; Nguyen Thi, H.; Billia, B.
2016-03-01
A two-dimensional multi-scale cellular automaton - finite element (CAFE) model is used to simulate grain structure evolution and microsegregation formation during solidification of refined Al-7wt%Si alloys under microgravity. The CAFE simulations are first qualitatively compared with the benchmark experimental data under microgravity. Qualitative agreement is obtained for the position of columnar to equiaxed transition (CET) and the CET transition mode (sharp or progressive). Further comparisons of the distributions of grain elongation factor and equivalent diameter are conducted and reveal a fair quantitative agreement.
Cellular Automata Model for Elastic Solid Material
Institute of Scientific and Technical Information of China (English)
DONG Yin-Feng; ZHANG Guang-Cai; XU Ai-Guo; GAN Yan-Biao
2013-01-01
The Cellular Automaton (CA) modeling and simulation of solid dynamics is a long-standing difficult problem.In this paper we present a new two-dimensional CA model for solid dynamics.In this model the solid body is represented by a set of white and black particles alternatively positioned in the x-and y-directions.The force acting on each particle is represented by the linear summation of relative displacements of the nearest-neighboring particles.The key technique in this new model is the construction of eight coefficient matrices.Theoretical and numerical analyses show that the present model can be mathematically described by a conservative system.So,it works for elastic material.In the continuum limit the CA model recovers the well-known Navier equation.The coefficient matrices are related to the shear module and Poisson ratio of the material body.Compared with previous CA model for solid body,this model realizes the natural coupling of deformations in the x-and y-directions.Consequently,the wave phenomena related to the Poisson ratio effects are successfully recovered.This work advances significantly the CA modeling and simulation in the field of computational solid dynamics.
Symbolic Computation Using Cellular Automata-Based Hyperdimensional Computing.
Yilmaz, Ozgur
2015-12-01
This letter introduces a novel framework of reservoir computing that is capable of both connectionist machine intelligence and symbolic computation. A cellular automaton is used as the reservoir of dynamical systems. Input is randomly projected onto the initial conditions of automaton cells, and nonlinear computation is performed on the input via application of a rule in the automaton for a period of time. The evolution of the automaton creates a space-time volume of the automaton state space, and it is used as the reservoir. The proposed framework is shown to be capable of long-term memory, and it requires orders of magnitude less computation compared to echo state networks. As the focus of the letter, we suggest that binary reservoir feature vectors can be combined using Boolean operations as in hyperdimensional computing, paving a direct way for concept building and symbolic processing. To demonstrate the capability of the proposed system, we make analogies directly on image data by asking, What is the automobile of air?
An archived multi-objective simulated annealing for a dynamic cellular manufacturing system
Shirazi, Hossein; Kia, Reza; Javadian, Nikbakhsh; Tavakkoli-Moghaddam, Reza
2014-05-01
To design a group layout of a cellular manufacturing system (CMS) in a dynamic environment, a multi-objective mixed-integer non-linear programming model is developed. The model integrates cell formation, group layout and production planning (PP) as three interrelated decisions involved in the design of a CMS. This paper provides an extensive coverage of important manufacturing features used in the design of CMSs and enhances the flexibility of an existing model in handling the fluctuations of part demands more economically by adding machine depot and PP decisions. Two conflicting objectives to be minimized are the total costs and the imbalance of workload among cells. As the considered objectives in this model are in conflict with each other, an archived multi-objective simulated annealing (AMOSA) algorithm is designed to find Pareto-optimal solutions. Matrix-based solution representation, a heuristic procedure generating an initial and feasible solution and efficient mutation operators are the advantages of the designed AMOSA. To demonstrate the efficiency of the proposed algorithm, the performance of AMOSA is compared with an exact algorithm (i.e., ∈-constraint method) solved by the GAMS software and a well-known evolutionary algorithm, namely NSGA-II for some randomly generated problems based on some comparison metrics. The obtained results show that the designed AMOSA can obtain satisfactory solutions for the multi-objective model.
Modeling and Simulation of Polarization in Internet Group Opinions Based on Cellular Automata
Directory of Open Access Journals (Sweden)
Yaofeng Zhang
2015-01-01
Full Text Available Hot events on Internet always attract many people who usually form one or several opinion camps through discussion. For the problem of polarization in Internet group opinions, we propose a new model based on Cellular Automata by considering neighbors, opinion leaders, and external influences. Simulation results show the following: (1 It is easy to form the polarization for both continuous opinions and discrete opinions when we only consider neighbors influence, and continuous opinions are more effective in speeding the polarization of group. (2 Coevolution mechanism takes more time to make the system stable, and the global coupling mechanism leads the system to consensus. (3 Opinion leaders play an important role in the development of consensus in Internet group opinions. However, both taking the opinion leaders as zealots and taking some randomly selected individuals as zealots are not conductive to the consensus. (4 Double opinion leaders with consistent opinions will accelerate the formation of group consensus, but the opposite opinions will lead to group polarization. (5 Only small external influences can change the evolutionary direction of Internet group opinions.
Directory of Open Access Journals (Sweden)
Kenneth Mubea
2014-01-01
Full Text Available This research explores urban growth based scenarios for the city of Nairobi using a cellular automata urban growth model (UGM. African cities have experienced rapid urbanization over the last decade due to increased population growth and high economic activities. We used multi-temporal Landsat imageries for 1976, 1986, 2000 and 2010 to investigate urban land-use changes in Nairobi. Our UGM used data from urban land-use of 1986 and 2010, road data, slope data and exclusion layer. Monte-Carlo technique was used for model calibration and Multi Resolution Validation (MRV technique for validation. Simulation of urban land-use was done up to the year 2030 when Kenya plans to attain Vision 2030. Three scenarios were explored in the urban modelling process; unmanaged growth with no restriction on environmental areas, managed growth with moderate protection, and a managed growth with maximum protection on forest, agricultural areas, and urban green. Thus alternative scenario development using UGM is useful for planning purposes so as to ensure sustainable development is achieved. UGM provides quantitative, visual, spatial and temporal information which aid policy and decision makers can make informed decisions.
Bergemann, Claudia; Elter, Patrick; Lange, Regina; Weißmann, Volker; Hansmann, Harald; Klinkenberg, Ernst-Dieter; Nebe, Barbara
2015-01-01
Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D) implants showed difficulties arising from impaired cellular proliferation and differentiation in the core region of these scaffolds with increasing scaffold volume in vitro. Therefore, we developed an in vitro perfusion cell culture module, which allows the analysis of cells in the interior of scaffolds under different medium flow rates. For each flow rate the cell viability was measured and compared with results from computer simulations that predict the local oxygen supply and shear stress inside the scaffold based on the finite element method. We found that the local cell viability correlates with the local oxygen concentration and the local shear stress. On the one hand the oxygen supply of the cells in the core becomes optimal with a higher perfusion flow. On the other hand shear stress caused by high flow rates impedes cell vitality, especially at the surface of the scaffold. Our results demonstrate that both parameters must be considered to derive an optimal nutrient flow rate. PMID:26539216
Directory of Open Access Journals (Sweden)
Claudia Bergemann
2015-01-01
Full Text Available Studies on bone cell ingrowth into synthetic, porous three-dimensional (3D implants showed difficulties arising from impaired cellular proliferation and differentiation in the core region of these scaffolds with increasing scaffold volume in vitro. Therefore, we developed an in vitro perfusion cell culture module, which allows the analysis of cells in the interior of scaffolds under different medium flow rates. For each flow rate the cell viability was measured and compared with results from computer simulations that predict the local oxygen supply and shear stress inside the scaffold based on the finite element method. We found that the local cell viability correlates with the local oxygen concentration and the local shear stress. On the one hand the oxygen supply of the cells in the core becomes optimal with a higher perfusion flow. On the other hand shear stress caused by high flow rates impedes cell vitality, especially at the surface of the scaffold. Our results demonstrate that both parameters must be considered to derive an optimal nutrient flow rate.
Ballarini, F.; Alloni, D.; Facoetti, A.; Mairani, A.; Nano, R.; Ottolenghi, A.
Astronauts in space are continuously exposed to low doses of ionizing radiation from Galactic Cosmic Rays During the last ten years the effects of low radiation doses have been widely re-discussed following a large number of observations on the so-called non targeted effects in particular bystander effects The latter consist of induction of cytogenetic damage in cells not directly traversed by radiation most likely as a response to molecular messengers released by directly irradiated cells Bystander effects which are observed both for lethal endpoints e g clonogenic inactivation and apoptosis and for non-lethal ones e g mutations and neoplastic transformation tend to show non-linear dose responses This might have significant consequences in terms of low-dose risk which is generally calculated on the basis of the Linear No Threshold hypothesis Although the mechanisms underlying bystander effects are still largely unknown it is now clear that two types of cellular communication i e via gap junctions and or release of molecular messengers into the extracellular environment play a fundamental role Theoretical models and simulation codes can be of help in elucidating such mechanisms In the present paper we will review different available modelling approaches including one that is being developed at the University of Pavia The focus will be on the different assumptions adopted by the various authors and on the implications of such assumptions in terms of non-targeted radiobiological damage and more generally low-dose
Game of Life Cellular Automata
Adamatzky, Andrew
2010-01-01
In the late 1960s, British mathematician John Conway invented a virtual mathematical machine that operates on a two-dimensional array of square cell. Each cell takes two states, live and dead. The cells' states are updated simultaneously and in discrete time. A dead cell comes to life if it has exactly three live neighbours. A live cell remains alive if two or three of its neighbours are alive, otherwise the cell dies. Conway's Game of Life became the most programmed solitary game and the most known cellular automaton. The book brings together results of forty years of study into computational
A derives grid-based model for simulation of pedestrian flow
Institute of Scientific and Technical Information of China (English)
Min-jie CHEN; Günter B(A)RWOLFF; Hartmut SCHWANDT
2009-01-01
We present a derived grid-based model for the simulation of pedestrian flow. Interactions among pedestrians are considered as the result of forces within a certain neighbourhood. Unlike the social force model, the forces here, as in Newtonian physics, are proportional to the inverse of the square of the distance. Despite the notion of neighbourhood and the underlying grid, this model differs from the existing cellular automaton (CA) models in that the pedestrians are treated as individuals. Bresenham's algorithm for line rastering is applied in the step calculation.
双目标推动下群体行为的元胞自动机模拟%Cellular automata simulation of group behavior driven by dual-targets
Institute of Scientific and Technical Information of China (English)
姚灿中; 杨建梅
2012-01-01
采用元胞自动机对自推动粒子改进模型进行模拟,在此基础上分别探讨无目标与双目标群体行为的演化特征.无目标条件下群体行为的元胞模拟结果显示低密度环境下大部分个体处于动态均衡,高密度环境下大部分个体处于静态均衡,中等密度下两种均衡均存在.基于双目标吸引力的群体行为模拟结果显示当智能体的理性程度较低时系统演化能够产生一定的集聚效应,处于吸引源以外的智能体与吸引源保持一定距离并呈湍流式运动,而当智能体具备小概率全局理性判断能力时,群体行为的演化结果为大部分智能体都聚集在吸引源附近.%This paper improves the self-propelled particle models by cellular automaton; through this model, the evolution characteristic of group behaviors is further studied in the conditions of non-target and dual-targets. The group behaviors simulation under the non-target condition shows that most individuals reach the dynamic equilibrium in low-density environment, most individuals are in static equilibrium in high-density environment, and both the static and the dynamic equilibrium exist in medium-density environment. The simulation results of group behaviors based on dual-targets attractiveness model show that when the agent's rational level is low, the system evolution can produce the concentration effect to a certain extent, and the agents outside the attracted source region maintain a certain distance with the source and the movement is turbulent. When the agents have the small probability of global rationality, the evolution results of group behaviors show that most agents gather in the vicinity of the attractive source.
Yang, Qing-Sheng; Qiao, Ji-Gang; Ai, Bin
2013-09-01
Taking the Dongguan City with rapid urbanization as a case, and selecting landscape ecological security level as evaluation criterion, the urbanization cellular number of 1 km x 1 km ecological security cells was obtained, and imbedded into the transition rules of cellular automata (CA) as the restraint term to control urban development, establish ecological security urban CA, and simulate ecological security urban development pattern. The results showed the integrated landscape ecological security index of the City decreased from 0.497 in 1998 to 0.395 in 2005, indicating that the ecological security at landscape scale was decreased. The CA-simulated integrated ecological security index of the City in 2005 was increased from the measured 0.395 to 0.479, showing that the simulated urban landscape ecological pressure from human became lesser, ecological security became better, and integrated landscape ecological security became higher. CA could be used as an effective tool in researching urban ecological security.
Incorporating scale invariance into the cellular associative neural network
Burles, Nathan; O'Keefe, Simon; Austin, James
2014-01-01
This paper describes an improvement to the Cellular Associative Neural Network, an architecture based on the distributed model of a cellular automaton, allowing it to perform scale invariant pattern matching. The use of tensor products and superposition of patterns allows the system to recall patterns at multiple resolutions simultaneously. Our experimental results show that the architecture is capable of scale invariant pattern matching, but that further investigation is needed to reduce the...
Renormalization group and continuum limit of quantum cellular automata
Energy Technology Data Exchange (ETDEWEB)
Zimboras, Zoltan [Quantum Information Theory Group, ISI, Torino (Italy)
2012-07-01
We develop a renormalization group formalism for quantum cellular automata (reminiscent of the algebraic renormalization group of Buchholz and Verch). Using this formalism, we can define the continuum limit for certain automata. As a particular example, we show that the continuum limit of the so-called ''Glider Clifford cellular automaton'' is the 1+1 dimensional relativistic QFT of free Majorana fermions.
Directory of Open Access Journals (Sweden)
Paulo Rangel Rios
2006-06-01
Full Text Available The effect of non-random nuclei location and the efficiency of microstructural descriptors in assessing such a situation are studied. Cellular automata simulation of recrystallization in two dimensions is carried out to simulate microstrutural evolution for nuclei distribution ranging from a periodic arrangement to clusters of nuclei. The simulation results are compared in detail with microstrutural descriptors normally used to follow transformation evolution. It is shown that the contiguity is particularly relevant to detect microstructural deviations from randomness. This work focuses on recrystallization but its results are applicable to any nucleation and growth transformation.
Chen Shijia; Guillemot Gildas; Gandin Charles-André
2013-01-01
Dans le domaine du soudage, les propriétés finales du cordon sont fortement liées à la structure de grains développée au cours des procédés de fusion / resolidification. La maîtrise des propriétés de l'assemblage final passe ainsi par une amélioration de la connaissance de sa structure de ce domaine. Dans cet objectif, un modèle couplé Automates Cellulaires – Eléments Finis est proposé pour simuler le développement, en volume, de cette structure, dans le cadre du soudage TIG. Ce modèle est ap...
Genetic Algorithm Calibration of Probabilistic Cellular Automata for Modeling Mining Permit Activity
Louis, S.J.; Raines, G.L.
2003-01-01
We use a genetic algorithm to calibrate a spatially and temporally resolved cellular automata to model mining activity on public land in Idaho and western Montana. The genetic algorithm searches through a space of transition rule parameters of a two dimensional cellular automata model to find rule parameters that fit observed mining activity data. Previous work by one of the authors in calibrating the cellular automaton took weeks - the genetic algorithm takes a day and produces rules leading to about the same (or better) fit to observed data. These preliminary results indicate that genetic algorithms are a viable tool in calibrating cellular automata for this application. Experience gained during the calibration of this cellular automata suggests that mineral resource information is a critical factor in the quality of the results. With automated calibration, further refinements of how the mineral-resource information is provided to the cellular automaton will probably improve our model.
Jokar Arsanjani, J.; Helbich, M.; Kainz, W.; Boloorani, A.
2013-01-01
This research analyses the suburban expansion in the metropolitan area of Tehran, Iran. A hybrid model consisting of logistic regression model, Markov chain (MC), and cellular automata (CA) was designed to improve the performance of the standard logistic regression model. Environmental and socio-eco
Directory of Open Access Journals (Sweden)
Castañeda-Camacho Josefina
2015-03-01
Full Text Available The smart antenna technology has received increasing interest due to its capability for improving the performance of wireless radio systems. In this work, we studied the throughput maximization in a digital cellular system when a smart antenna array is implemented. We focus, in the study of the downlink of a 3G cellular system and consider a packet data direct-sequence code division, multiple access (DS-CDMA. Our methodology is based on the Monte Carlo simulation technique, and it is used to show that it is possible to obtain a significant increment in the throughput of the system due to the switched beam smart antenna array. From our results we conclude that it is feasible to consider the application of this technology in 4G environments.
Using synchronization to improve the forecasting of large relaxations in a cellular-automaton model
DEFF Research Database (Denmark)
González, Á.; Gómez, J.B.; Vázquez-Prada, M.;
2004-01-01
phenomena. In the new strategy, copies (clones) of the original system (the master) are defined, and they are driven using rules that tend to synchronize them with the master dynamics. The observation of definite patterns in the state of the clones is the signal for connecting an alarm in the original...
Lorentz symmetry for 3d Quantum Cellular Automata
Bisio, Alessandro; Perinotti, Paolo
2015-01-01
We introduce a definition of Lorentz transformations in the framework of quantum cellular automata. Our definition does not require space-time, and retains the usual interpretation in the emergent one. The definition is group theoretical, with flatness of space-time corresponding to Abelianity of the cellular automaton group. We consider the covariance in the case of the Weyl automaton. The notion of particle as Poincar\\'e irreducible representation survives at all scales. The interpolation of the Lorentz symmetry from the discrete to the continuum scale occurs through a nonlinear representation. We also discuss the connection of the nonlinear Lorentz transformations with the Poincar\\'e and k-Poincar\\'e Hopf algebra, the emerging non-commutative space-time, and the deformed Heisenberg commutation relations.
Signal Waveform Detection with Statistical Automaton for Internet and Web Service Streaming
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Kuo-Kun Tseng
2014-01-01
Full Text Available In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.
Signal waveform detection with statistical automaton for internet and web service streaming.
Tseng, Kuo-Kun; Ji, Yuzhu; Liu, Yiming; Huang, Nai-Lun; Zeng, Fufu; Lin, Fang-Ying
2014-01-01
In recent years, many approaches have been suggested for Internet and web streaming detection. In this paper, we propose an approach to signal waveform detection for Internet and web streaming, with novel statistical automatons. The system records network connections over a period of time to form a signal waveform and compute suspicious characteristics of the waveform. Network streaming according to these selected waveform features by our newly designed Aho-Corasick (AC) automatons can be classified. We developed two versions, that is, basic AC and advanced AC-histogram waveform automata, and conducted comprehensive experimentation. The results confirm that our approach is feasible and suitable for deployment.
Efficient Uplink Modeling for Dynamic System-Level Simulations of Cellular and Mobile Networks
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Lobinger Andreas
2010-01-01
Full Text Available A novel theoretical framework for uplink simulations is proposed. It allows investigations which have to cover a very long (real- time and which at the same time require a certain level of accuracy in terms of radio resource management, quality of service, and mobility. This is of particular importance for simulations of self-organizing networks. For this purpose, conventional system level simulators are not suitable due to slow simulation speeds far beyond real-time. Simpler, snapshot-based tools are lacking the aforementioned accuracy. The runtime improvements are achieved by deriving abstract theoretical models for the MAC layer behavior. The focus in this work is long term evolution, and the most important uplink effects such as fluctuating interference, power control, power limitation, adaptive transmission bandwidth, and control channel limitations are considered. Limitations of the abstract models will be discussed as well. Exemplary results are given at the end to demonstrate the capability of the derived framework.
Energy Technology Data Exchange (ETDEWEB)
Meireles, Sincler P. de; Santos, Adriano M.; Grynberg, Suely Epsztein, E-mail: spm@cdtn.b, E-mail: amsantos@cdtn.b, E-mail: seg@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Nunes, Maria Eugenia S., E-mail: mariaeugenia@iceb.ufop.b [Universidade Federal de Ouro Preto (UFOP), MG (Brazil)
2011-07-01
During recent years, there has been a shift from an approach focused entirely on DNA as the main target of ionizing radiation to a vision that considers complex signaling pathways in cells and among cells within tissues. Several newly recognized responses were classified as the so-called non-target responses in which the biological effects are not directly related to the amount of energy deposited in the DNA of cells that were traversed by radiation. In 1992 the bystander effect was described referring to a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. In this work, we have developed a mathematical model via cellular automata, to quantify cell death induced by the bystander effect. The model is based on experiments with irradiated cells conditioned medium which suggests that irradiated cells secrete molecules in the medium that are capable of damaging other cells. The computational model consists of two-dimensional cellular automata which is able to simulate the transmission of bystander signals via extrinsic route and via Gap junctions. The model has been validated by experimental results in the literature. The time evolution of the effect and the dose-response curves were obtained in good accordance to them. Simulations were conducted for different values of bystander and irradiated cell densities with constant dose. From this work, we have obtained a relationship between cell density and effect. (author)
International Nuclear Information System (INIS)
During recent years, there has been a shift from an approach focused entirely on DNA as the main target of ionizing radiation to a vision that considers complex signaling pathways in cells and among cells within tissues. Several newly recognized responses were classified as the so-called non-target responses in which the biological effects are not directly related to the amount of energy deposited in the DNA of cells that were traversed by radiation. In 1992 the bystander effect was described referring to a series of responses such as death, chromosomal instability or other abnormalities that occur in non-irradiated cells that came into contact with irradiated cells or medium from irradiated cells. In this work, we have developed a mathematical model via cellular automata, to quantify cell death induced by the bystander effect. The model is based on experiments with irradiated cells conditioned medium which suggests that irradiated cells secrete molecules in the medium that are capable of damaging other cells. The computational model consists of two-dimensional cellular automata which is able to simulate the transmission of bystander signals via extrinsic route and via Gap junctions. The model has been validated by experimental results in the literature. The time evolution of the effect and the dose-response curves were obtained in good accordance to them. Simulations were conducted for different values of bystander and irradiated cell densities with constant dose. From this work, we have obtained a relationship between cell density and effect. (author)
Chiu, Brian; Z-M Wan, Jim; Abley, Doris; Akabutu, John
2005-05-01
Recent studies have demonstrated that stem cells derived from adult hematopoietic tissues are capable of trans-differentiation into non-hematopoietic cells, and that the culture in microgravity ( μg) may modulate the proliferation and differentiation. We investigated the application of μg to human umbilical cord blood stem cells (CBSC) in the induction of vascular endothelial phenotype expression and cellular proliferation. CD34+ mononuclear cells were isolated from waste human umbilical cord blood samples and cultured in simulated μg for 14 days. The cells were seeded in rotary wall vessels (RWV) with or without microcarrier beads (MCB) and vascular endothelial growth factor was added during culture. Controls consisted of culture in 1 G. The cell cultures in RWV were examined by inverted microscopy. Cell counts, endothelial cell and leukocyte markers performed by flow-cytometry and FACS scan were assayed at days 1, 4, 7 and at the termination of the experiments. Culture in RWV revealed significantly increased cellular proliferation with three-dimensional (3D) tissue-like aggregates. At day 4, CD34+ cells cultured in RWV bioreactor without MCB developed vascular tubular assemblies and exhibited endothelial phenotypic markers. These data suggest that CD34+ human umbilical cord blood progenitors are capable of trans-differentiation into vascular endothelial cell phenotype and assemble into 3D tissue structures. Culture of CBSC in simulated μg may be potentially beneficial in the fields of stem cell biology and somatic cell therapy.
Directory of Open Access Journals (Sweden)
Dr.E.N.Ganesh
2010-08-01
Full Text Available Quantum cellular automata (QCA is a new technology in the nanometer scale and has been considered as one of the alternative to CMOS technology. QCA have a large potential in the development of circuits with high space density and low heat dissipation and allow the development of faster computers with lower power consumption. This paper discusses the design and construction of simple two bit arithmetic logic unit , four bit shifter and carry save in multiplier circuits. The advantage of this type of ALU is to construct functional unit all around the input lines and thereby reducing circuit complexity. Four bit shifter are constructed using serial AND and OR QCA circuits. QCA multiplier designed and constructed here has advantage of carry save in by delaying one clock cycle and no of bits can also be increased by adding the full adder stages. These circuits are the building block of nanoprocessors and provide us to understand the nanodevices of the future.
A tunable cancer cell filter using magnetic beads: cellular and fluid dynamic simulations
Gusenbauer, Markus; Bance, Simon; Exl, Lukas; Reichel, Franz; Oezelt, Harald; Schrefl, Thomas
2011-01-01
In the field of biomedicine magnetic beads are used for drug delivery and to treat hyperthermia. Here we propose to use self-organized bead structures to isolate circulating tumor cells using lab-on-chip technologies. Typically blood flows past microposts functionalized with antibodies for circulating tumor cells. Creating these microposts with interacting magnetic beads makes it possible to tune the geometry in size, position and shape. We develop a simulation tool that combines micromagnetics, discrete particle dynamics and fluid dynamics, in order to design micropost arrays made of interacting beads. For the simulation of blood flow we use the Lattice-Boltzmann method with immersed elastic blood cell models. Parallelization distributes large fluid and particle dynamic simulations over available resources to reduce overall calculation time.
Simulation of the dynamics in the magnetotail current sheet
Ojeda, Arian; Calzadilla, Alexander; Savio, Siomel; Alazo, Katy
2013-01-01
The dynamics in the magnetosphere current sheet was simulated following transformations to the rectangular NxM array of cells (cellular automaton) originally proposed by Koselov and Koselova (2002). The magnetosphere part of the modeling system was organized as a rectangular arrangement of cells with a stored energy, a local redistribution of the energy will exist when a value threshold is exceeded in one of the cells. We assume that the threshold value in each cell depends on external control parameter which influences the long boundaries of the rectangular array (40x80). The model dynamics controlled by the z-component of the interplanetary magnetic field (Bz) as well as analogies between the model transient processes and the observed substorm auroral activations are discussed. The Bz correspond to temporary windows of the solar wind for a group of magnetic clouds and plasmoids. The model simulates organized patterns in the energy distribution. The function of distribution of probability (or PDF) of the siz...
Jankovic, D.
2005-01-01
Numerical modeling of moisture flow, drying shrinkage and crack phenomena in cement microstructure, by coupling a Lattice Gas Automaton and a Lattice Fracture Model, highlighted the importance of a shrinkage coefficient (sh) as the most significant parameter for achieving realistic numerical result
The Research of Image Encryption Algorithm Based on Chaos Cellular Automata
Directory of Open Access Journals (Sweden)
Shuiping Zhang
2012-02-01
Full Text Available The Research presents an image encryption algorithm which bases on chaotic cellular automata. This algorithm makes use of features that extreme sensitivity of chaotic system to initial conditions, the cellular automaton with a high degree of parallel processing. The encryption algorithm uses two-dimensional chaotic system to Encrypt image, Then establish a cellular automaton model on the initial encrypted image. Encryption key of this algorithm is made up of the initial value by the two-dimensional chaotic systems, parameters, two-dimensional cellular automata local evolution rules f and iterations n. Experimental results shows that the algorithm has features that high efficiency, better security, sensitivity to the key and so on.
Estimation of cellular manufacturing cost components using simulation and activity-based costing
Directory of Open Access Journals (Sweden)
Paul Savory
2010-06-01
Full Text Available It can be difficult estimating all of the cost components that are attributed to a machined part. This problem is more pronounced when a factory uses group technology manufacturing cells as opposed to a functional or process layout of a job shop. This paper describes how activity-based costing (ABC concepts can be integrated into a discrete-event simulation model of a U-shaped manufacturing cell producing a part family with four members. The simulation model generates detailed Bills of Activity for each part type and includes specific information about the cost drivers and cost pools. The enhanced model output can be used for cost estimation and analysis, manufacturing cell design, part scheduling and other manufacturing decision processes that involve economic considerations. Although the scope of this effort is restricted to a small scale manufacturing cell, the costing concepts have general applicability to manufacturing operations at all levels.
Judge, Valentine; Antoni, Jean-Philippe
2015-01-01
National audience Nowadays land use evolution study has become a major stake in urban planning. The main focus is to understand the way in which land use evolves across time and to understand processes that take place. This understanding would allow to plan urban developments based on a knowledge as complete as possible covering as many fields as possible (i.e. urban planning, politics, sociology, etc.). Simulation tools can be used to merge and display different points of view and stakes ...
The Universe as Automaton From Simplicity and Symmetry to Complexity
Mainzer, Klaus
2012-01-01
This booklet is an essay at the interface of philosophy and complexity research, trying to inspire the reader with new ideas and new conceptual developments of cellular automata. Going beyond the numerical experiments of Steven Wolfram, it is argued that cellular automata must be considered complex dynamical systems in their own right, requiring appropriate analytical models in order to find precise answers and predictions in the universe of cellular automata. Indeed, eventually we have to ask whether cellular automata can be considered models of the real world and, conversely, whether there are limits to our modern approach of attributing the world, and the universe for that matter, essentially a digital reality.
SAR Simulation with Magneto Chiral Effects for Human Head Radiated from Cellular Phones
Torres-Silva, H.
2008-09-01
A numerical method for a microwave signal emitted by a cellular phone, propagating in a magneto-chiral media, characterized by an extended Born-Fedorov formalism, is presented. It is shown that the use of a cell model, combined with a real model of the human head, derived from the magnetic resonance of images allows a good determination of the near fields induced in the head when the brain chirality and the battery magnetic field are considered together. The results on a 2-Dim human head model show the evolution of the specific absorption rate, (SAR coefficient) and the spatial peak specific absorption rate which are sensitives to the magneto-chiral factor, which is important in the brain layer. For GSM/PCN phones, extremely low frequency real pulsed magnetic fields (in the order of 10 to 60 milligauss) are added to the model through the whole of the user's head. The more important conclusion of our work is that the head absorption is bigger than the results for a classical model without the magneto chiral effect. Hot spots are produced due to the combination of microwave and the magnetic field produced by the phone's operation. The FDTD method was used to compute the SARs inside the MRI based head models consisting of various tissues for 1.8 GHz. As a result, we found that in the head model having more than four kinds of tissue, the localized peak SAR reaches maximum inside the head for over five tissues including skin, bone, blood and brain cells.
Feliciani, Claudio; Nishinari, Katsuhiro
2016-06-01
In this article we present an improved version of the Cellular Automata floor field model making use of a sub-mesh system to increase the maximum density allowed during simulation and reproduce phenomena observed in dense crowds. In order to calibrate the model's parameters and to validate it we used data obtained from an empirical observation of bidirectional pedestrian flow. A good agreement was found between numerical simulation and experimental data and, in particular, the double outflow peak observed during the formation of deadlocks could be reproduced in numerical simulations, thus allowing the analysis of deadlock formation and dissolution. Finally, we used the developed high density model to compute the flow-ratio dependent fundamental diagram of bidirectional flow, demonstrating the instability of balanced flow and predicting the bidirectional flow behavior at very high densities. The model we presented here can be used to prevent dense crowd accidents in the future and to investigate the dynamics of the accidents which already occurred in the past. Additionally, fields such as granular and active matter physics may benefit from the developed framework to study different collective phenomena.
Directory of Open Access Journals (Sweden)
Jun Yang
2013-01-01
Full Text Available Spatiotemporal simulation of tourist town growth is important for research on land use/cover change under the influence of urbanization. Many scholars have shown great interest in the unique pattern of driving urban development with tourism development. Based on the cellular automata (CA model, we simulated and predicted the spatiotemporal growth of Sanpo town in Hebei Province, using the tourism urbanization growth model. Results showed that (1 average annual growth rate of the entire region was 1.5 Ha2 per year from 2005 to 2010, 4 Ha2 per year from 2010 to 2015, and 2.5 Ha2 per year from 2015 to 2020; (2 urban growth rate increased yearly, with regional differences, and had a high degree of correlation with the Euclidean distance of town center, traffic route, attractions, and other factors; (3 Gougezhuang, an important village center in the west of the town, demonstrated traffic advantages and increased growth rate since 2010; (4 Magezhuang village has the largest population in the region, so economic advantages have driven the development of rural urbanization. It showed that CA had high reliability in simulating the spatiotemporal evolution of tourist town, which assists the study of spatiotemporal growth under urbanization and rational protection of tourism resources.
Cell-centred model for the simulation of curved cellular monolayers
Mosaffa, Payman; Asadipour, Nina; Millán, Daniel; Rodríguez-Ferran, Antonio; J Muñoz, Jose
2015-12-01
This paper presents a cell-centred model for the simulation of planar and curved multicellular soft tissues. We propose a computational model that includes stress relaxation due to cell reorganisation (intercellular connectivity changes) and cytoskeleton remodelling (intracellular changes). Cells are represented by their cell centres, and their mechanical interaction is modelled through active non-linear elastic laws with a dynamically changing resting length. Special attention is paid to the handling of connectivity changes between cells, and the relaxation that the tissues exhibit under these topological changes. Cell-cell connectivity is computed by resorting to a Delaunay triangulation, which is combined with a mapping technique in order to obtain triangulations on curved manifolds. Our numerical results show that even a linear elastic cell-cell interaction model may induce a global non-linear response due to the reorganisation of the cell connectivity. This plastic-like behaviour is combined with a non-linear rheological law where the resting length depends on the elastic strain, mimicking the global visco-elastic response of tissues. The model is applied to simulate the elongation of planar and curved monolayers.
Directory of Open Access Journals (Sweden)
Ángel Monteagudo
Full Text Available Cancer can be viewed as an emergent behavior in terms of complex system theory and artificial life, Cellular Automata (CA being the tool most used for studying and characterizing the emergent behavior. Different approaches with CA models were used to model cancer growth. The use of the abstract model of acquired cancer hallmarks permits the direct modeling at cellular level, where a cellular automaton defines the mitotic and apoptotic behavior of cells, and allows for an analysis of different dynamics of the cellular system depending on the presence of the different hallmarks. A CA model based on the presence of hallmarks in the cells, which includes a simulation of the behavior of Cancer Stem Cells (CSC and their implications for the resultant growth behavior of the multicellular system, was employed. This modeling of cancer growth, in the avascular phase, was employed to analyze the effect of cancer treatments in a cancer stem cell context. The model clearly explains why, after treatment against non-stem cancer cells, the regrowth capability of CSCs generates a faster regrowth of tumor behavior, and also shows that a continuous low-intensity treatment does not favor CSC proliferation and differentiation, thereby allowing an unproblematic control of future tumor regrowth. The analysis performed indicates that, contrary to the current attempts at CSC control, trying to make CSC proliferation more difficult is an important point to consider, especially in the immediate period after a standard treatment for controlling non-stem cancer cell proliferation.
Fluctuation in option pricing using cellular automata based market models
Gao, Yuying; Beni, Gerardo
2005-05-01
A new agent-based Cellular Automaton (CA) computational algorithm for option pricing is proposed. CAs have been extensively used in modeling complex dynamical systems but not in modeling option prices. Compared with traditional tools, which rely on guessing volatilities to calculate option prices, the CA model is directly addressing market mechanisms and simulates price fluctuation from aggregation of actions made by interacting individual market makers in a large population. This paper explores whether CA models can provide reasonable good answers to pricing European options. The Black-Scholes model and the Binomial Tree model are used for comparison. Comparison reveals that CA models perform reasonably well in pricing options, reproducing overall characteristics of random walk based model, while at the same time providing plausible results for the 'fat-tail' phenomenon observed in many markets. We also show that the binomial tree model can be obtained from a CA rule. Thus, CA models are suitable tools to generalize the standard theories of option pricing.
Coordination and Emergence in the Cellular Automated Fashion Game
Cao, Zhigang; Qu, Xinglong; Yang, Mingmin; Yang, Xiaoguang
2012-01-01
We investigate a heterogeneous cellular automaton, where there are two types of agents, conformists and rebels. Each agent has to choose between two actions, 0 and 1. A conformist likes to choose an action that most of her neighbors choose, while in contrast a rebel wants to be different with most of her neighbors. Theoretically, this model is equivalent to the matching pennies game on regular networks. We study the dynamical process by assuming that each agent takes a myopic updating rule. An uniform updating probability is also introduced for each agent to study the whole spectrum from synchronous updating to asynchronous updating. Our model characterizes the phenomenon of fashion very well and has a great potential in the study of the finance and stock markets. A large number of simulations show that in most case agents can reach extraordinarily high degree of coordination. This process is also quite fast and steady. Considering that these dynamics are really simple, agents are selfish, myopic, and have ve...
Calculation of impulse responses with a cellular automata algorithm
Barjau, Ana
2001-05-01
The air columns in musical instruments usually have a predominant dimension and thus are very often modeled as 1D systems where uniparametric waves propagate. Different algorithms can be found in the literature to simulate this propagation. The more widely used are finite difference schemes and delay lines. A finite difference scheme (FD) is a numerical integration of a differential formulation (the wave equation), while delay lines (DL) use analytical exact solutions of the wave equation over finite lengths. A new and different approach is that of a cellular automaton (CA) scheme. The underlying philosophy is opposite those of FD and DL, as the starting point is not the wave equation. In a CA approach, the phenomenon to be studied is reduced to a few simple physical laws that are applied to a set of cells representing the physical system (in the present case, the propagation medium). In this paper, a CA will be proposed to obtain the impulse response of different bore geometries. The results will be compared to those obtained with other algorithms.
Simulation of nanoparticle based enhancement of cellular electroporation for biomedical applications
Qiu, Hao; Joshi, Ravindra P.; Pradhan, Aswini
2014-11-01
Introduction of nanoparticles can modify electrical properties such as the permittivity and conductivity of a medium. This model based study focuses on such modulated changes of an extracellular medium from the standpoint of enhancing electroporation to achieve more efficient delivery into biological cells. A finite element, time-dependent axisymmetric bio-model, coupled with the Smoluchowski equation, has been used to evaluate the transmembrane potentials and evolution of pore densities. Our simulation results show that a relatively small fraction of gold nanoparticles in the extracellular medium effectively enhances the transmembrane potentials, leads to much higher pore densities, and shifts the pore distribution towards larger radii. This collectively bodes well for enhancing drug delivery or gene transfection in cells.
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
This paper presents a development of the extended Cellular Automata (CA), based on relational databases(RDB), to model dynamic interactions among spatial objects. The integration of Geographical Information System (GIS)and CA has the great advantage of simulating geographical processes. But standard CA has some restrictions in cellularshape and neighbourhood and neighbour rules, which restrict the CA's ability to simulate complex, real world environ-ments. This paper discusses a cell's spatial relation based on the spatial object's geometrical and non-geometrical characteris-tics, and extends the cell' s neighbour definition, and considers that the cell' s neighbour lies in the forms of not only spa-tial adjacency but also attribute correlation. This paper then puts forward that spatial relations between two different cellscan be divided into three types, including spatial adjacency, neighbourhood and complicated separation. Based on tradition-al ideas, it is impossible to settle CA's restrictions completely. RDB-based CA is an academic experiment, in whichsome fields are designed to describe the essential information needed to define and select a cell's neighbour. The cultureinnovation diffusion system has multiple forms of space diffusion and inherited characteristics that the RDB-based CA iscapable of simulating more effectively. Finally this paper details a successful case study on the diffusion of fashion weartrends. Compared to the original CA, the RDB-based CA is a more natural and efficient representation of human knowl-edge over space, and is an effective tool in simulating complex systems that have multiple forms of spatial diffusion.
Asymptotic Behavior of Excitable Cellular Automata
Durrett, R; Durrett, Richard; Griffeath, David
1993-01-01
Abstract: We study two families of excitable cellular automata known as the Greenberg-Hastings Model (GHM) and the Cyclic Cellular Automaton (CCA). Each family consists of local deterministic oscillating lattice dynamics, with parallel discrete-time updating, parametrized by the range of interaction, the "shape" of its neighbor set, threshold value for contact updating, and number of possible states per site. GHM and CCA are mathematically tractable prototypes for the spatially distributed periodic wave activity of so-called excitable media observed in diverse disciplines of experimental science. Earlier work by Fisch, Gravner, and Griffeath studied the ergodic behavior of these excitable cellular automata on Z^2, and identified two distinct (but closely-related) elaborate phase portraits as the parameters vary. In particular, they noted the emergence of asymptotic phase diagrams (and Euclidean dynamics) in a well-defined threshold-range scaling limit. In this study we present several rigorous results and som...
Stochastic simulation of radium-223 dichloride therapy at the sub-cellular level.
Gholami, Y; Zhu, X; Fulton, R; Meikle, S; El-Fakhri, G; Kuncic, Z
2015-08-01
Radium-223 dichloride ((223)Ra) is an alpha particle emitter and a natural bone-seeking radionuclide that is currently used for treating osteoblastic bone metastases associated with prostate cancer. The stochastic nature of alpha emission, hits and energy deposition poses some challenges for estimating radiation damage. In this paper we investigate the distribution of hits to cells by multiple alpha particles corresponding to a typical clinically delivered dose using a Monte Carlo model to simulate the stochastic effects. The number of hits and dose deposition were recorded in the cytoplasm and nucleus of each cell. Alpha particle tracks were also visualized. We found that the stochastic variation in dose deposited in cell nuclei ([Formula: see text]40%) can be attributed in part to the variation in LET with pathlength. We also found that [Formula: see text]18% of cell nuclei receive less than one sigma below the average dose per cell ([Formula: see text]15.4 Gy). One possible implication of this is that the efficacy of cell kill in alpha particle therapy need not rely solely on ionization clustering on DNA but possibly also on indirect DNA damage through the production of free radicals and ensuing intracellular signaling. PMID:26216391
Institute of Scientific and Technical Information of China (English)
ZHU Jinsong; HE Likun
2012-01-01
Abstract In order to accurately simulate the diffusion of chloride ion in the existing concrete bridge and acquire the precise chloride ion concentration at given time,a cellular automata (CA)-based model is proposed.The process of chloride ion diffusion is analyzed by the CA-based method and a nonlinear solution of the Fick's second law is obtained.Considering the impact of various factors such as stress states,temporal and spatial variability of diffusion parameters and water-cement ratio on the process of chloride ion diffusion,the model of chloride ion diffusion under multi-factor coupling actions is presented.A chloride ion penetrating experiment reported in the literature is used to prove the effectiveness and reasonability of the present method,and a T-type beam is taken as an illustrative example to analyze the process of chloride ion diffusion in practical application.The results indicate that CA-based method can simulate the diffusion of chloride ion in the concrete structures with acceptable precision.
Computer simulation of tumour growth and cellular phase distribution prior to radiotherapy
International Nuclear Information System (INIS)
Full text: A study into the optimal fractionation and schedule in combined chemo-radiotherapy for head and neck cancer has imposed the development of a computer model of tumour growth. The model is based on biological parameters, and characterises tumour growth and eventual tumour regression when chemo-radiotherapy is used. Tumour growth starting from a single stem cell is modelled using the Monte Carlo method. The type of the cell function, their relative proportions on mitosis, their proliferative capacity, the duration of the four phases of the cell cycle, the mean cell cycle time, and the cell loss due to natural causes are the main parameters of the basic model. A Gaussian distribution function operates in establishing the cell cycle time, with a mean value of 26 hours, while the cell type is sampled from a uniform distribution. With the established model, the sensitivity of the developed tumour's cell population to the stem, proliferative and non proliferative ratio at mitosis was assessed. The present model accurately reflects the exponential distribution of cells along the cell cycle (70% cells in G1 phase, 15% in S, 10% in G2, 5% in M) of a developed tumour as described in the literature. The proportion of stem, finitely proliferating and resting cells during tumour growth is maintained within their biological limits (2% stem. 23% finitely proliferating, 75% nonproliferating cells). The ratio (R=3) between the time necessary to develop a clinically detectable tumour (109 cells) and the time to grow to its lethal size (1012 cells) is in accordance with the biological data when tumour volume is compared for the two periods (30 doublings and 10 doublings respectively). Computer simulation can illustrate the biological growth of a tumour and the cell distribution along the cell cycle. These distributions may than be used in the assessment of tumour response to radiotherapy and to specific chemotherapeutic agents. Copyright (2001) Australasian College of
Jankovic, D.
2005-01-01
Numerical modeling of moisture flow, drying shrinkage and crack phenomena in cement microstructure, by coupling a Lattice Gas Automaton and a Lattice Fracture Model, highlighted the importance of a shrinkage coefficient (sh) as the most significant parameter for achieving realistic numerical results. Therefore, experiments on drying of cement paste samples were conducted in an Environmental Scanning Electron Microscope to find shrinkage coefficient relating shrinkage deformations and moistur...
Liu, Yaolin; Kong, Xuesong; Liu, Yanfang; Chen, Yiyun
2013-01-01
Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS) and cellular automata (CA). The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans.
Directory of Open Access Journals (Sweden)
Yaolin Liu
Full Text Available Rapid urbanization in China has triggered the conversion of land from rural to urban use, particularly the conversion of rural settlements to town land. This conversion is the result of the joint effects of the geographic environment and agents involving the government, investors, and farmers. To understand the dynamic interaction dominated by agents and to predict the future landscape of town expansion, a small town land-planning model is proposed based on the integration of multi-agent systems (MAS and cellular automata (CA. The MAS-CA model links the decision-making behaviors of agents with the neighbor effect of CA. The interaction rules are projected by analyzing the preference conflicts among agents. To better illustrate the effects of the geographic environment, neighborhood, and agent behavior, a comparative analysis between the CA and MAS-CA models in three different towns is presented, revealing interesting patterns in terms of quantity, spatial characteristics, and the coordinating process. The simulation of rural settlements conversion to town land through modeling agent decision and human-environment interaction is very useful for understanding the mechanisms of rural-urban land-use change in developing countries. This process can assist town planners in formulating appropriate development plans.
International Nuclear Information System (INIS)
This paper introduces a design methodology in the context of finding new and innovative design principles by means of optimization techniques. In this method cellular automata (CA) and simulated annealing (SA) were combined and used for solving the optimization problem. This method contains two principles that are neighboring concept from CA and accepting each displacement basis on decreasing of objective function and Boltzman distribution from SA that plays role of transition rule. Proposed method was used for solving fuel management optimization problem in VVER-1000 Russian reactor. Since the fuel management problem contains a huge amount of calculation for finding the best configuration for fuel assemblies in reactor core this method has been introduced for reducing the volume of calculation. In this study reducing of power peaking factor inside the reactor core of Bushehr NPP is considered as the objective function. The proposed optimization method is compared with Hopfield neural network procedure that was used for solving this problem and has been shown that the result, velocity and qualification of new method are comparable with that. Besides, the result is the optimum configuration, which is in agreement with the pattern proposed by the designer.
Indian Academy of Sciences (India)
KAMAL DEEP; PARDEEP K SINGH
2016-09-01
In this paper, an integrated mathematical model of multi-period cell formation and part operation tradeoff in a dynamic cellular manufacturing system is proposed in consideration with multiple part process route. This paper puts emphasize on the production flexibility (production/subcontracting part operation) to satisfy the product demand requirement in different period segments of planning horizon considering production capacity shortage and/or sudden machine breakdown. The proposed model simultaneously generates machine cells and part families and selects the optimum process route instead of the user specifying predetermined routes. Conventional optimization method for the optimal cell formation problem requires substantial amount of time and memory space. Hence a simulated annealing based genetic algorithm is proposed to explore the solution regions efficiently and to expedite the solution search space. To evaluate the computability of the proposed algorithm, different problem scenarios are adopted from literature. The results approve the effectiveness of theproposed approach in designing the manufacturing cell and minimization of the overall cost, considering various manufacturing aspects such as production volume, multiple process route, production capacity, machine duplication, system reconfiguration, material handling and subcontracting part operation.
Continuous limit of a crowd motion and herding model: Analysis and numerical simulations
Pietschmann, Jan-Frederik
2011-11-01
In this paper we study the continuum limit of a cellular automaton model used for simulating human crowds with herding behaviour. We derive a system of non-linear partial differential equations resembling the Keller-Segel model for chemotaxis, however with a non-monotone interaction. The latter has interesting consequences on the behaviour of the model\\'s solutions, which we highlight in its analysis. In particular we study the possibility of stationary states, the formation of clusters and explore their connection to congestion. We also introduce an efficient numerical simulation approach based on an appropriate hybrid discontinuous Galerkin method, which in particular allows flexible treatment of complicated geometries. Extensive numerical studies also provide a better understanding of the strengths and shortcomings of the herding model, in particular we examine trapping effects of crowds behind nonconvex obstacles. © American Institute of Mathematical Sciences.
Cellular automata in image processing and geometry
Adamatzky, Andrew; Sun, Xianfang
2014-01-01
The book presents findings, views and ideas on what exact problems of image processing, pattern recognition and generation can be efficiently solved by cellular automata architectures. This volume provides a convenient collection in this area, in which publications are otherwise widely scattered throughout the literature. The topics covered include image compression and resizing; skeletonization, erosion and dilation; convex hull computation, edge detection and segmentation; forgery detection and content based retrieval; and pattern generation. The book advances the theory of image processing, pattern recognition and generation as well as the design of efficient algorithms and hardware for parallel image processing and analysis. It is aimed at computer scientists, software programmers, electronic engineers, mathematicians and physicists, and at everyone who studies or develops cellular automaton algorithms and tools for image processing and analysis, or develops novel architectures and implementations of mass...
SELF-ORGANIZED CRITICALITY AND CELLULAR AUTOMATA
Energy Technology Data Exchange (ETDEWEB)
CREUTZ,M.
2007-01-01
Cellular automata provide a fascinating class of dynamical systems based on very simple rules of evolution yet capable of displaying highly complex behavior. These include simplified models for many phenomena seen in nature. Among other things, they provide insight into self-organized criticality, wherein dissipative systems naturally drive themselves to a critical state with important phenomena occurring over a wide range of length and the scales. This article begins with an overview of self-organized criticality. This is followed by a discussion of a few examples of simple cellular automaton systems, some of which may exhibit critical behavior. Finally, some of the fascinating exact mathematical properties of the Bak-Tang-Wiesenfeld sand-pile model [1] are discussed.
Liu, L.; Liu, Y.; Wang, X.; Yu, D.; Liu, K.; Huang, H.; Hu, G.
2015-03-01
Flash floods have occurred frequently in the urban areas of southern China. An effective process-oriented urban flood inundation model is urgently needed for urban storm-water and emergency management. This study develops an efficient and flexible cellular automaton (CA) model to simulate storm-water runoff and the flood inundation process during extreme storm events. The process of infiltration, inlets discharge and flow dynamics can be simulated with little preprocessing on commonly available basic urban geographic data. In this model, a set of gravitational diverging rules are implemented to govern the water flow in a rectangular template of three cells by three cells of a raster layer. The model is calibrated by one storm event and validated by another in a small urban catchment in Guangzhou of southern China. The depth of accumulated water at the catchment outlet is interpreted from street-monitoring closed-circuit television (CCTV) videos and verified by on-site survey. A good level of agreement between the simulated process and the reality is reached for both storm events. The model reproduces the changing extent and depth of flooded areas at the catchment outlet with an accuracy of 4 cm in water depth. Comparisons with a physically based 2-D model (FloodMap) show that the model is capable of effectively simulating flow dynamics. The high computational efficiency of the CA model can meet the needs of city emergency management.
Saad, Ali; Gandin, Charles-André; Bellet, Michel; Shevchenko, Natalia; Eckert, Sven
2015-11-01
Freckles are common defects in industrial casting. They result from thermosolutal convection due to buoyancy forces generated from density variations in the liquid. The present paper proposes a numerical analysis for the formation of channel segregation using the three-dimensional (3D) cellular automaton (CA)—finite element (FE) model. The model integrates kinetics laws for the nucleation and growth of a microstructure with the solution of the conservation equations for the casting, while introducing an intermediate modeling scale for a direct representation of the envelope of the dendritic grains. Directional solidification of a cuboid cell is studied. Its geometry, the alloy chosen as well as the process parameters are inspired from experimental observations recently reported in the literature. Snapshots of the convective pattern, the solute distribution, and the morphology of the growth front are qualitatively compared. Similitudes are found when considering the coupled 3D CAFE simulations. Limitations of the model to reach direct simulation of the experiments are discussed.
Tree Automaton Based Algorithms for Sub-Typing and inDOM Relations in XQuery
Institute of Scientific and Technical Information of China (English)
XIE Rong-chuan; XIE Xuan-yang
2004-01-01
Proposed by W3C(World Wide Web Consortium),XQuery is a descriptive query language for XML structured data or documents.The specification of XQuery gives functional description of XQuery's typing system, but doestn't provide methods to judge the Sub-typing and inDOM relations in language compiling.In this paper, both of the two important relations:Sub-typing and inDOM, are described and analyzed.After some definitions of Tree Automaton, the judgment algorithms of these two relations are proposed.
3D similar pattern generation of snow crystals with cellular automata%基于元胞自动化模型的三维雪花晶体近似模式的产生
Institute of Scientific and Technical Information of China (English)
李芳佳; 高尚策; 唐政; 石井雅博; 山下和也
2009-01-01
Computer simulation of snow crystal growing process has been done for many years. Cellular automaton is a computing model which is made from lattice cells and simple rules. Though it is a very simple model, it gives good results when used to imitate complex processes such as the life phenomenon, crystal growth and the turbulent flow. In this paper, a cellular model for 3Dimensional snow crystallization was proposed by extending the traditional 2-Dimensional cellular model. Simulation results indicated that the proposed model can accurately simulate most 3-Dimensional snow erystaUization processes.%关于雪花生长过程的计算机模拟已经受到了广泛关注.其中,元胞自动化模型是一种基于网格和简单规则的计算方法.尽管这是一种简单的模型,但其在模拟复杂过程(比如:生命现象,晶体生长和湍流)时往往能取得较好的结果.提出了一种由传统的二维模型扩展而来的三维雪花晶体生长方法.计算机模拟结果显示提出的方法能够更精确地模拟出三维雪花的晶体化过程.
Microscopic simulation of multi-lane traffic under dynamic tolling and information feedback
Institute of Scientific and Technical Information of China (English)
LIU Tian-liang; HUANG Hai-jun; TIAN Li-jun
2009-01-01
To investigate drivers' lane-changing behavior under different information feedback strategies, a microscopic traffic simulation based on the cellular automaton model was made on the typical freeway with a regular lane and a high-occupancy one. A new dynamic tolling scheme in terms of the real-time traffic condition on the high-occupancy lane was further designed to enhance the whole freeway's flow throughput. The results show that the mean velocity feedback strategy is generally more efficient than the travel time feedback strategy in correctly guiding drivers' lane choice behavior. Specifically, the toll level, lane-changing rate and freeway's throughput and congestion coefficient induced by the travel time feedback strategy oscillate with larger amplitude and longer period. In addition, the dynamic tolling scheme can make the high-occupancy lane less congested and maximize the freeway's throughput when the regular-lane inflow rate is larger than 0.45.
A cellular automata model of Ebola virus dynamics
Burkhead, Emily; Hawkins, Jane
2015-11-01
We construct a stochastic cellular automaton (SCA) model for the spread of the Ebola virus (EBOV). We make substantial modifications to an existing SCA model used for HIV, introduced by others and studied by the authors. We give a rigorous analysis of the similarities between models due to the spread of virus and the typical immune response to it, and the differences which reflect the drastically different timing of the course of EBOV. We demonstrate output from the model and compare it with clinical data.
Endy, Drew; Brent, Roger
2001-01-01
Representations of cellular processes that can be used to compute their future behaviour would be of general scientific and practical value. But past attempts to construct such representations have been disappointing. This is now changing. Increases in biological understanding combined with advances in computational methods and in computer power make it possible to foresee construction of useful and predictive simulations of cellular processes.
Cellular automata-based tunnel fire simulation%基于元胞自动机的井巷火灾仿真
Institute of Scientific and Technical Information of China (English)
李翠平; 胡磊; 侯定勇; 张佳
2013-01-01
提出了一种基于元胞自动机的井巷火灾可视化仿真方法。在矿井巷道可视化的基础上，通过对火灾元胞进行表征，综合考虑可燃物类型与投放密度、井巷通风、井巷坡度等因素对井巷火源引燃效果的影响及双扩散作用、井巷通风、浮力作用和节流作用等因素对火灾烟气蔓延效果的影响，采用概率函数进行元胞自动机建模，构建了表达元胞温度的井巷火源燃烧模型和表达元胞浓度的井巷火灾烟气蔓延模型。基于火源元胞燃烧演化规则和烟气元胞蔓延演化规则，通过可视化手段展示了井巷火灾火源燃烧和有害气体浓度的时空发展变化。同时以矿山实际数据进行检验，说明了基于元胞自动机的井巷火灾仿真的可行性与有效性。%This article introduces a mine fire visualization simulation method based on cellular automata. On the basis of mine tunnel visualization, a tunnel fire combustion model for expressing cellular temperature and a tunnel fire smoke spread model for expressing cellular concentration were built by fire cell characterization. In these models the influence of fuel type and input density, ventilation and roadway slope on mine fire ignition and the effect of double diffusion, ventilation, buoyancy and throttling on fire smoke spread were taken into account, and a probability function was used for cellular automata modelling. Then according to the fire cellular combustion evolution rules and smoke cellular spreading evolution rules, the spatial changes of tunnel fire burning and harmful gas concentration were demonstrated through visualization means. Actual data from a mine proves the feasibility and effectiveness of tunnel fire simulation based on cellular automata.
Finite Automaton Based Strategy for Automated Trust Negotiation%基于有穷自动机的自动信任协商策略
Institute of Scientific and Technical Information of China (English)
李健利; 刘博; 邓潇
2013-01-01
自动信任协商通过协商策略协调协商双方间访问控制策略、信任证的交互披露以逐步建立信任.现有的访问控制策略规则的理论表示缺乏直观性,在分析和构造策略算法时带来不便.本文将有穷自动机形式化定义与自动信任协商相结合,提出一套基于有穷自动机的信任协商定义体系,并构造有穷自动机状态转换图对相应的访问控制策略进行图形化表示,便于分析和构造协商策略.针对积极策略缺乏安全性和谨慎策略缺乏高效性的问题,提出了基于有穷自动机的协商策略,该策略在谨慎策略的基础上加入记忆链结构,以减少协商双方交互次数,提高协商效率.经证明,该策略具备完备性和安全性,并通过仿真实验证明相对于谨慎策略,该策略具备高效性.%Automated Trust Negotiation is used to gradually establish the trust between strangers by negotiation strategies that coordinate the strangers to iterative disclosure of access control policies and credentials.The theory expression of access control policies'rules lack of the property of directviewing,it goes against to analyze and construct the strategy's algorithm.Through the combination of formal definition of finite automaton with trust negotiation,a new definition system of negotiation based on finite automaton was proposed,and the finite automaton transition diagrams were constructed to represent corresponding access control policies equivalently by graphs,it was propitious to analyze and construct strategies.For problems which the eager strategy lacked security and the prudent strategy lacked high efficiency,a finite automaton based strategy was proposed,which was added to a structure called memory chain on the basis of prudent strategy so as to reduce the frequency of the communication and improve the negotiating efficiency.The strategy was proved to be provided with completeness and safety,and compared with the prudent strategy
A Continuous-Action Learning Automaton for Stochastic Optimization%一种用于随机优化的连续动作学习自动机
Institute of Scientific and Technical Information of China (English)
刘晓
2015-01-01
Learning automaton( LA) is a stochastic optimization technique where the goal of the automaton is to choose the optimal action out of a set of allowable actions.In most of the existing LA,the action set is finite.Hence,for continuous parameter learning problems,the action space needs to be discretized and the accuracy of the solutions depends on the level of discretization.A new continuous-action learning au-tomaton( CALA) is proposed in this paper.The action set of the automaton is a variable interval,actions are selected according to a uniform distribution over this interval.The two endpoints of the interval are up-dated by using a recently best action which is determined in a manner similar to the simulated annealing scheme.Simulation results are given to show the advantages of the proposed algorithm over three of the existing CALA algorithms for optimization a noise-corrupted,multi-modal function.%学习自动机（ LA）是一种随机优化技术，其中自动机的目标是从一个允许的动作集里选择最优的动作。现有LA的动作集大多都是有限集，因此对于连续参数学习问题，需要将动作空间离散化，并且解的精度取决于离散化的颗粒度。提出一种新的连续动作学习自动机（ CALA），其动作集为一个可变区间，并依照均匀分布选择输出动作。算法通过一种类似提高拟退火的方式确定一个“最新且最好”的动作，并根据该动作对区间的两个端点进行更新。通过优化一个被噪声污损的多模态函数的仿真实验，演示了新算法相对于三种现有的CALA算法的优越性。
Visualization of Patterns and Self-organization of Cellular Automata in Urban Traffic Situations
Zhou, Lei; Brian, Schwartz
2001-06-01
The use of cellular automaton (CA) techniques is very good at modeling complex or nonlinear systems. In dynamic system within the context of discrete mathematical steps for CA simulations, simple local rules produce complex global rules. The simplicity of CA rules enables us to model and investigate more realistic models for the behavior traffic in two-dimensional flow systems. Our numerical solution presents self-organization behavior, which is called grid-lock for urban city street traffic and a phase transitions in the fundamental flow rate vs. density diagrams. We present calculations, which demonstrate the effects of micro CA rules and traffic parameters on the macro properties of traffic flow and behavior. We modified the stochastic parameter p, which is constant in the original CA rules, to a variable depending on the state of the vehicles. This structure of path dependence on history for traffic properties is in many cases analogous to solutions obtained for interactive magnetic systems. Using 3D ray tracer software, we are able to render the visualization of patterns of grid-lock into a 3D virtual urban environment.
Dauphin, C.; Vilmer, N.; Anastasiadis, A.
2007-06-01
Context: We study the acceleration and radiation of electrons and ions interacting with multiple small-scale dissipation regions resulting from the magnetic energy release process. Aims: We aim to calculate the distribution functions of the kinetic energy of the particles and the X-ray spectra and γ-ray fluxes produced by the accelerated particles. Methods: The evolution of the magnetic energy released in an active region is mimicked by a cellular automaton model based on the concept of self-organized criticality. Each burst of magnetic energy release is associated with a reconnecting current sheet (RCS) in which the particles are accelerated by a direct electric field. Results: We calculate the energy gain of the particles (ions and electrons) for three different magnetic configurations of the RCS after their interactions with a given number of RCS. We finally compare our results with existing observations. Conclusions: The results of our simulation can reproduce several properties of the observations such as variable electron and ion energy contents and γ-ray line ratio. Even if very flat X-ray spectra have been reported in a few events, the X-ray spectra produced in this model are too flat when compared to most X-ray observations.
Quantum dot spin cellular automata for realizing a quantum processor
International Nuclear Information System (INIS)
We show how single quantum dots, each hosting a singlet–triplet qubit, can be placed in arrays to build a spin quantum cellular automaton. A fast (∼10 ns) deterministic coherent singlet–triplet filtering, as opposed to current incoherent tunneling/slow-adiabatic based quantum gates (operation time ∼300 ns), can be employed to produce a two-qubit gate through capacitive (electrostatic) couplings that can operate over significant distances. This is the coherent version of the widely discussed charge and nano-magnet cellular automata, and would increase speed, reduce dissipation, and perform quantum computation while interfacing smoothly with its classical counterpart. This combines the best of two worlds—the coherence of spin pairs known from quantum technologies, and the strength and range of electrostatic couplings from the charge-based classical cellular automata. Significantly our system has zero electric dipole moment during the whole operation process, thereby increasing its charge dephasing time. (paper)
Directory of Open Access Journals (Sweden)
M. Thirumaran
2016-04-01
Full Text Available Incorporating changes into the logics of composed services dynamically and successfully is a challenge for sustaining a business’ image and profit in the society, especially when the change is expected to be made immediately at low cost. In this paper, we address this challenge by proposing a change impact analysis framework for long term composed services (LCS which: (i enables the business people to implement the changes by themselves through their analysts, (ii reduces cost and time by eliminating the dependence on IT developers once the application services are developed and delivered, (iii ensures effective incorporation of the changes made by using standard methodologies for evaluation – finite state automaton for verifying the runtime compatibilities and change evaluation and probabilistic cellular automaton for impact analysis and prediction. Through the evaluated probability measures and effective incident matching, the knowledge gained by the analyst over his service logics and the efficiency of incorporating changes are increased.
Javaheri Javid, Mohammad Ali; Blackwell, Tim; Zimmer, Robert; Majid al-Rifaie, Mohammad
2016-04-01
Shannon entropy fails to discriminate structurally different patterns in two-dimensional images. We have adapted information gain measure and Kolmogorov complexity to overcome the shortcomings of entropy as a measure of image structure. The measures are customised to robustly quantify the complexity of images resulting from multi-state cellular automata (CA). Experiments with a two-dimensional multi-state cellular automaton demonstrate that these measures are able to predict some of the structural characteristics, symmetry and orientation of CA generated patterns.
Institute of Scientific and Technical Information of China (English)
He Gong; Yubo Fan; Ming Zhang
2008-01-01
The objective of this paper is to identify the effects of mechanical disuse and basic multi-cellular unit (BMU) activation threshold on the form of trabecular bone during menopause. A bone adaptation model with mechanical-biological factors at BMU level was integrated with finite element analysis to simulate the changes of trabecular bone structure during menopause. Mechanical disuse and changes in the BMU activation threshold were applied to the model for the period from 4 years before to 4 years after menopause.The changes in bone volume fraction, trabecular thickness and fractal dimension of the trabecular structures were used to quantify the changes of trabecular bone in three different cases associated with mechanical disuse and BMU activation threshold. It was found that the changes in the simulated bone volume fraction were highly correlated and consistent with clinical data, and that the trabecular thickness reduced signi-ficantly during menopause and was highly linearly correlated with the bone volume fraction, and that the change trend of fractal dimension of the simulated trabecular structure was in correspondence with clinical observations. The numerical simulation in this paper may help to better understand the relationship between the bone morphology and the mecha- nical, as well as biological environment; and can provide a quantitative computational model and methodology for the numerical simulation of the bone structural morphological changes caused by the mechanical environment, and/or the biological environment.
Simulation of pedestrian evacuation based on an improved dynamic parameter model
Institute of Scientific and Technical Information of China (English)
Zhu Nuo; Jia Bin; Shao Chun-Fu; Yue Hao
2012-01-01
An improved dynamic parameter model is presented based on cellular automata.The dynamic parameters,including direction parameter,empty parameter,and cognition parameter,are formulated to simplify tactically the process of making decisions for pedestrians.The improved model reflects the judgement of pedestrians on surrounding conditions and the action of choosing or decision.According to the two-dimensional cellular automaton Moore neighborhood we establish the pedestrian moving rule,and carry out corresponding simulations of pedestrian evacuation.The improved model considers the impact of pedestrian density near exits on the evacuation process.Simulated and experimental results demonstrate that the improvement makes sense due to the fact that except for the spatial distance to exits,people also choose an exit according to the pedestrian density around exits.The impact factors α,β,and γ are introduced to describe transition payoff,and their optimal values are determined through simulation.Moreover,the effects of pedestrian distribution,pedestrian density,and the width of exits on the evacuation time are discussed.The optimal exit layout,i.e.,the optimal position and width,is offered.The comparison between the simulated results obtained with the improved model and that from a previous model and experiments indicates that the improved model can reproduce experimental results well.Thus,it has great significance for further study,and important instructional meaning for pedestrian evacuation so as to reduce the number of casualties.
de la Cruz, Roberto; Spill, Fabian; Alarcón, Tomás
2016-01-01
We propose a modelling framework to analyse the stochastic behaviour of heterogeneous, multi-scale cellular populations. We illustrate our methodology with a particular example in which we study a population with an oxygen-regulated proliferation rate. Our formulation is based on an age-dependent stochastic process. Cells within the population are characterised by their age. The age-dependent (oxygen-regulated) birth rate is given by a stochastic model of oxygen-dependent cell cycle progression. We then formulate an age-dependent birth-and-death process, which dictates the time evolution of the cell population. The population is under a feedback loop which controls its steady state size: cells consume oxygen which in turns fuels cell proliferation. We show that our stochastic model of cell cycle progression allows for heterogeneity within the cell population induced by stochastic effects. Such heterogeneous behaviour is reflected in variations in the proliferation rate. Within this set-up, we have established...
Codd, E F
1968-01-01
Cellular Automata presents the fundamental principles of homogeneous cellular systems. This book discusses the possibility of biochemical computers with self-reproducing capability.Organized into eight chapters, this book begins with an overview of some theorems dealing with conditions under which universal computation and construction can be exhibited in cellular spaces. This text then presents a design for a machine embedded in a cellular space or a machine that can compute all computable functions and construct a replica of itself in any accessible and sufficiently large region of t
Qiu, Menglong; Wang, Qi; Li, Fangbai; Chen, Junjian; Yang, Guoyi; Liu, Liming
2016-01-01
A customized logistic-based cellular automata (CA) model was developed to simulate changes in heavy metal contamination (HMC) in farmland soils of Dongguan, a manufacturing center in Southern China, and to discover the relationship between HMC and related explanatory variables (continuous and categorical). The model was calibrated through the simulation and validation of HMC in 2012. Thereafter, the model was implemented for the scenario simulation of development alternatives for HMC in 2022. The HMC in 2002 and 2012 was determined through soil tests and cokriging. Continuous variables were divided into two groups by odds ratios. Positive variables (odds ratios >1) included the Nemerow synthetic pollution index in 2002, linear drainage density, distance from the city center, distance from the railway, slope, and secondary industrial output per unit of land. Negative variables (odds ratios polluting enterprises, distance from the town center, soil pH, and distance from bodies of water. Categorical variables, including soil type, parent material type, organic content grade, and land use type, also significantly influenced HMC according to Wald statistics. The relative operating characteristic and kappa coefficients were 0.91 and 0.64, respectively, which proved the validity and accuracy of the model. The scenario simulation shows that the government should not only implement stricter environmental regulation but also strengthen the remediation of the current polluted area to effectively mitigate HMC.
Simulation of Forest Fire Spreading Based on Geographic Cellular Automata%林火蔓延地理元胞自动机仿真模拟
Institute of Scientific and Technical Information of China (English)
湛玉剑; 张帅; 张磊; 刘学军
2013-01-01
On the basis of geographical cellular automata, a forest fire spread simulation model which applied in the complex diversity of tree species is proposed for the complexity of the impact of forest fire spread factors in this paper. Meanwhile ,GIS technology, which is convenient to CA forest fire spread model for its ability to handle and analysis raster data and other abilities, is used to design and achieve a dynamic simulation of the spread model in this paper. Simulation results show that the model can simulate forest fire spread of different environments, and is suitable for simulation analyzing forest fire spread under the combined effects of various factors ,and also can provide technical support for prediction analysis of fire spread,estimating fire shape,burned area and the rate of spread and optimizing fire suppression decision-making.%针对林火蔓延影响因子的复杂性,在地理元胞自动机的基础上,提出一种应用于具有复杂树种多样性的林火蔓延模拟模型,同时借助GIS技术实现了蔓延模型的动态模拟.实验结果表明,模型可以模拟不同环境下的林火蔓延,适用于仿真分析多种因素综合作用下的林火蔓延,能够为预测分析火势蔓延趋势,估算火场形状、过火面积、蔓延速度以及优化灭火决策等提供技术支持.
International Nuclear Information System (INIS)
14 MeV neutrons are used to irradiate human melanoma cells in order to study survival curves at low dose and low dose rate. We have simulated with the MCNP code, transport of neutrons through the experimental setup to evaluate the contamination of the primary beam by gamma and electrons, for the feasibility of our experiments. We have shown a rapid decrease of the survival curve in the first cGy followed by a plateau for doses up to 30 cGy; after we observed an exponential decrease. This results are observed for the first time, for neutrons at low dose rate (5 cGy/h). In parallel with this experimental point, we have developed a simulation code which permitted the study of neutrons interactions with the cellular medium for individual cells defined as in our experimental conditions. We show that most of the energy is deposited by protons from neutron interactions with external medium, and by heavy ions for interactions into the cell. On the other hand the code gives a good order of magnitude of the dose rate, compared to the experimental values given by silicon diodes. The first results show that we can, using a theory based on induced repair of cells, give an interpretation of the observed experimental plateau. We can give an estimation of the radial distribution of dose for the tracks of charged ions, we show the possibility of calculate interaction cross sections with cellular organelles. Such a work gives interesting perspectives for the future in radiobiology, radiotherapy or radioprotection. (author)
Kuentz, M
2003-01-01
A two-dimensional lattice gas automaton (LGA) is used for simulating concentration-dependent diffusion in a microscopically random heterogeneous structure. The heterogeneous medium is initialized at a low density rho sub 0 and then submitted to a steep concentration gradient by continuous injection of particles at a concentration rho sub 1 >rho sub 0 from a one-dimensional source to model spreading of a density front. Whereas the nonlinear diffusion equation generally used to describe concentration-dependent diffusion processes predicts a scaling law of the type phi = xt sup - sup 1 sup / sup 2 in one dimension, the spreading process is shown to deviate from the expected t sup 1 sup / sup 2 scaling. The time exponent is found to be larger than 1/2, i.e. diffusion of the density front is enhanced with respect to standard Fickian diffusion. It is also established that the anomalous time exponent decreases as time elapses: anomalous spreading is thus not a timescaling process. We demonstrate that occurrence of a...
APFA: Asynchronous Parallel Finite Automaton for Deep Packet Inspection in Cloud Computing
Li, Yang; Li, Zheng; Yu, Nenghai; Ma, Ke
Security in cloud computing is getting more and more important recently. Besides passive defense such as encryption, it is necessary to implement real-time active monitoring, detection and defense in the cloud. According to the published researches, DPI (deep packet inspection) is the most effective technology to realize active inspection and defense. However, most recent works of DPI aim at space reduction but could not meet the demands of high speed and stability in the cloud. So, it is important to improve regular methods of DPI, making it more suitable for cloud computing. In this paper, an asynchronous parallel finite automaton named APFA is proposed, by introducing the asynchronous parallelization and the heuristically forecast mechanism, which significantly decreases the time consumed in matching while still keeps reducing the memory required. What is more, APFA is immune to the overlapping problem so that the stability is also enhanced. The evaluation results show that APFA achieves higher stability, better performance on time and memory. In short, APFA is more suitable for cloud computing.
Directory of Open Access Journals (Sweden)
Divya Selvaraj
2014-01-01
Full Text Available Packet content scanning is one of the crucial threats to network security and network monitoring applications. In monitoring applications, payload of packets in a network is matched against the set of patterns in order to detect attacks like worms, viruses, and protocol definitions. During network transfer, incoming and outgoing packets are monitored in depth to inspect the packet payload. In this paper, the regular expressions that are basically string patterns are analyzed for packet payloads in detecting worms. Then the grouping scheme for regular expression matching is rewritten using Deterministic Finite Automaton (DFA. DFA achieves better processing speed during regular expression matching. DFA requires more memory space for each state. In order to reduce memory utilization, decompression technique is used. Delayed Dictionary Compression (DDC is applied for achieving better speeds in the communication links. DDC achieves decoding latency during compression of payload packets in the network. Experimental results show that the proposed approach provides better time consumption and memory utilization during detection of Internet worm attacks.
Microstructure simulation of rapidly solidified ASP30 high-speed steel particles by gas atomization
Ma, Jie; Wang, Bo; Yang, Zhi-liang; Wu, Guang-xin; Zhang, Jie-yu; Zhao, Shun-li
2016-03-01
In this study, the microstructure evolution of rapidly solidified ASP30 high-speed steel particles was predicted using a simulation method based on the cellular automaton-finite element (CAFE) model. The dendritic growth kinetics, in view of the characteristics of ASP30 steel, were calculated and combined with macro heat transfer calculations by user-defined functions (UDFs) to simulate the microstructure of gas-atomized particles. The relationship among particle diameter, undercooling, and the convection heat transfer coefficient was also investigated to provide cooling conditions for simulations. The simulated results indicated that a columnar grain microstructure was observed in small particles, whereas an equiaxed microstructure was observed in large particles. In addition, the morphologies and microstructures of gas-atomized ASP30 steel particles were also investigated experimentally using scanning electron microscopy (SEM). The experimental results showed that four major types of microstructures were formed: dendritic, equiaxed, mixed, and multi-droplet microstructures. The simulated results and the available experimental data are in good agreement.
Institute of Scientific and Technical Information of China (English)
陈守东; 陈敬超; 吕连灏
2012-01-01
The width of columnar grain zone in as cast strips is mainly determined by the length of columnar grains at nip point. Coupling temperature field, concentration field and micro growth, the simulation of the solidification structure on the solidification process of pure aluminum in water-cooled steel mould of twin-roll continuous casting was presented by CA-FE method in Procast. The model was built according to Cellular Automaton model and the locally functioned law of grain growth was established. By this model, the solidification of the single-phase pure aluminum was simulation and studied on the grain scale. By use of this model,the effects of process parameters on the solidification structure were studied. The calculation results fit the experimental ones well, and then the validity and the applicability of the model were tested.%鉴于双辊薄带连铸等轴晶区半固态铸轧组织对产品性能的重要性,应用Procast软件中的CA-FE方法对工业纯铝在水冷钢辊连续铸轧中的凝固过程进行了模拟,建立了宏观温度场、浓度场和微观生长过程耦合的凝固组织模拟模型.以CA(Cellular Automaton)模型为基础,建立了晶粒生长过程的局部演变规则,在晶粒尺度上模拟了其凝固过程.应用建立的微观组织模型,研究了工艺参数对凝固组织的影响.模拟结果与实验结果基本吻合,检验了模型的正确性与适用条件.
基于元胞自动机的海上溢油扩散模拟%Simulation of marine oil spill diffusion based on cellular automata
Institute of Scientific and Technical Information of China (English)
2015-01-01
利用逻辑回归算法和决策树C5.0算法分别获取溢油扩散的转换规则，并构建了基于逻辑回归的CA模型和决策树CA模型。这两个模型仅需要设置起始影像、影响因子和权重等少数的变量，便可以方便地模拟出溢油的动态变化情况。把逻辑回归CA模型和决策树CA模型应用到DeepSpill项目的海上溢油模拟实验，结果表明逻辑回归CA模型的模拟总精度达到96.4%，Kappa系数达0.893，而决策树CA模型的模拟结果更为理想，其精度和kappa系数分别提高了0.2%和0.006。利用元胞自动机能够很好地模拟并预测出海上溢油的动态变化，可以满足对溢油快速响应的要求。%Cellular automata (CA) is an effective tool for simulating geographical process. In this paper, logistic regression and decision tree algorithm (C5.0) are introduced to obtain transition rules, which are used to build logistic regression CA model and decision-tree CA model. These two models are very convenient because they only need a few variables, such as starting image, impact factors and weights. And the simulation results of oil spill can be obtained. The logistic regression CA model and decision-tree CA model are applied to simulate the movement of oil spill in Deep Spill projects. Experiment re-sults showed that the overall accuracy and Kappa coefficient of simulation results in logistic regression CA were 96.4%and 0.893.Better results could be obtained using decision-tree CA model. Its overall accuracy and kappa coefficients increased by 0.2%and 0.006. Our experiment results showed that the CA models could simulate the dynamic changes of the oil spill and meet the requirements for rapid response of governments.
Institute of Scientific and Technical Information of China (English)
杨周
1996-01-01
Cellular phones, used in automobiles, airliners, and passenger trains, are basically low-power radiotelephones. Calls go through radio transmitters that are located within small geographical units called cells. Because each cell’s signals are too weak to interfere with those of other cells operating on the same fre-
Robust tracking by cellular automata and neural networks with nonlocal weights
Ososkov, Gennadii A.
1995-04-01
A modified rotor model of the Hopfield neural networks (HNN) is proposed for finding tracks in multiwire proportional chambers. That requires us to apply both raw data prefiltering by cellular automaton and HNN weights furnishing by a special robust multiplier. Then this model is developed to be applicable for a more general type of data and detectors. As an example, data processing of ionospheric measurements are considered. For handling tracks detected by high pressure drift chambers with their up-down ambiguity a modification of deformable templates method is proposed. A new concept of controlled HNN is proposed for solving the so-called track-match problem.
Threshold-Range Scaling of Excitable Cellular Automata
Fisch, R; Griffeath, D; Fisch, Robert; Gravner, Janko; Griffeath, David
1993-01-01
Each cell of a two-dimensional lattice is painted one of k colors, arranged in a "color wheel." The colors advance (0 to k-1 mod k) either automatically or by contact with at least a threshold number of successor colors in a prescribed local neighborhood. Discrete-time parallel systems of this sort in which color 0 updates by contact and the rest update automatically are called Greenberg-Hastings (GH) rules. A system in which all colors update by contact is called a cyclic cellular automaton (CCA). Started from appropriate initial conditions these models generate periodic traveling waves. Started from random configurations the same rules exhibit complex self-organization, typically characterized by nucleation of locally periodic "ram's horns" or spirals. Corresponding random processes give rise to a variety of "forest fire" equilibria that display large-scale stochastic wave fronts. This article describes a framework, theoretically based, but relying on extensive interactive computer graphics experimentation,...
A new small-world network created by Cellular Automata
Ruan, Yuhong; Li, Anwei
2016-08-01
In this paper, we generate small-world networks by the Cellular Automaton based on starting with one-dimensional regular networks. Besides the common properties of small-world networks with small average shortest path length and large clustering coefficient, the small-world networks generated in this way have other properties: (i) The edges which are cut in the regular network can be controlled that whether the edges are reconnected or not, and (ii) the number of the edges of the small-world network model equals the number of the edges of the original regular network. In other words, the average degree of the small-world network model equals to the average degree of the original regular network.
Directory of Open Access Journals (Sweden)
Xu Qingyan
2012-02-01
Full Text Available Directional solidified turbine blades of Ni-based superalloy are widely used as key parts of the gas turbine engines. The mechanical properties of the blade are greatly influenced by the final microstructure and the grain orientation determined directly by the grain selector geometry of the casting. In this paper, mathematical models were proposed for three dimensional simulation of the grain growth and microstructure evolution in directional solidification of turbine blade casting. Ray-tracing method was applied to calculate the temperature variation of the blade. Based on the thermo model of heat transfer, the competitive grain growth within the starter block and the spiral of the grain selector, the grain growth in the blade and the microstructure evolution were simulated via a modified Cellular Automaton method. Validation experiments were carried out, and the measured results were compared quantitatively with the predicted results. The simulated cooling curves and microstructures corresponded well with the experimental results. The proposed models could be used to predict the grain morphology and the competitive grain evolution during directional solidification.
Modeling evolution and immune system by cellular automata
Energy Technology Data Exchange (ETDEWEB)
Bezzi, M. [Scuola Internazionale Superiore di Studi Avanzati, Trieste (Italy); Istituto Nazionale di Fisica della Materia, Florence (Italy)
2001-07-01
In this review the behavior of two different biological systems is investigated using cellular automata. Starting from this spatially extended approach it is also tried, in some cases, to reduce the complexity of the system introducing mean-field approximation, and solving (or trying to solve) these simplified systems. It is discussed the biological meaning of the results, the comparison with experimental data (if available) and the different features between spatially extended and mean-field versions. The biological systems considered in this review are the following: Darwinian evolution in simple ecosystems and immune system response. In the first section the main features of molecular evolution are introduced, giving a short survey of genetics for physicists and discussing some models for prebiotic systems and simple ecosystems. It is also introduced a cellular automaton model for studying a set of evolving individuals in a general fitness landscape, considering also the effects of co-evolution. In particular the process of species formation (speciation) is described in sect. 5. The second part deals with immune system modeling. The biological features of immune response are discussed, as well as it is introduced the concept of shape space and of idiotypic network. More detailed reviews which deal with immune system models (mainly focused on idiotypic network models) can be found. Other themes here discussed: the applications of CA to immune system modeling, two complex cellular automata for humoral and cellular immune response. Finally, it is discussed the biological data and the general conclusions are drawn in the last section.
Modeling evolution and immune system by cellular automata
International Nuclear Information System (INIS)
In this review the behavior of two different biological systems is investigated using cellular automata. Starting from this spatially extended approach it is also tried, in some cases, to reduce the complexity of the system introducing mean-field approximation, and solving (or trying to solve) these simplified systems. It is discussed the biological meaning of the results, the comparison with experimental data (if available) and the different features between spatially extended and mean-field versions. The biological systems considered in this review are the following: Darwinian evolution in simple ecosystems and immune system response. In the first section the main features of molecular evolution are introduced, giving a short survey of genetics for physicists and discussing some models for prebiotic systems and simple ecosystems. It is also introduced a cellular automaton model for studying a set of evolving individuals in a general fitness landscape, considering also the effects of co-evolution. In particular the process of species formation (speciation) is described in sect. 5. The second part deals with immune system modeling. The biological features of immune response are discussed, as well as it is introduced the concept of shape space and of idiotypic network. More detailed reviews which deal with immune system models (mainly focused on idiotypic network models) can be found. Other themes here discussed: the applications of CA to immune system modeling, two complex cellular automata for humoral and cellular immune response. Finally, it is discussed the biological data and the general conclusions are drawn in the last section
Progresses in the Analysis of Stochastic 2D Cellular Automata: a Study of Asynchronous 2D Minority
Regnault, Damien; Thierry, Éric
2007-01-01
Cellular automata are often used to model systems in physics, social sciences, biology that are inherently asynchronous. Over the past 20 years, studies have demonstrated that the behavior of cellular automata drastically changed under asynchronous updates. Still, the few mathematical analyses of asynchronism focus on one-dimensional probabilistic cellular automata, either on single examples or on specific classes. As for other classic dynamical systems in physics, extending known methods from one- to two-dimensional systems is a long lasting challenging problem. In this paper, we address the problem of analysing an apparently simple 2D asynchronous cellular automaton: 2D Minority where each cell, when fired, updates to the minority state of its neighborhood. Our experiments reveal that in spite of its simplicity, the minority rule exhibits a quite complex response to asynchronism. By focusing on the fully asynchronous regime, we are however able to describe completely the asymptotic behavior of this dynamics...
MIMO Communication for Cellular Networks
Huang, Howard; Venkatesan, Sivarama
2012-01-01
As the theoretical foundations of multiple-antenna techniques evolve and as these multiple-input multiple-output (MIMO) techniques become essential for providing high data rates in wireless systems, there is a growing need to understand the performance limits of MIMO in practical networks. To address this need, MIMO Communication for Cellular Networks presents a systematic description of MIMO technology classes and a framework for MIMO system design that takes into account the essential physical-layer features of practical cellular networks. In contrast to works that focus on the theoretical performance of abstract MIMO channels, MIMO Communication for Cellular Networks emphasizes the practical performance of realistic MIMO systems. A unified set of system simulation results highlights relative performance gains of different MIMO techniques and provides insights into how best to use multiple antennas in cellular networks under various conditions. MIMO Communication for Cellular Networks describes single-user,...
Directory of Open Access Journals (Sweden)
Hang Zhang
2014-02-01
Full Text Available The rapid development of numerical modeling techniques has led to more accurate results in modeling metal solidification processes. In this study, the cellular automaton-finite difference (CA-FD method was used to simulate the directional solidification (DS process of single crystal (SX superalloy blade samples. Experiments were carried out to validate the simulation results. Meanwhile, an intelligent model based on fuzzy control theory was built to optimize the complicate DS process. Several key parameters, such as mushy zone width and temperature difference at the cast-mold interface, were recognized as the input variables. The input variables were functioned with the multivariable fuzzy rule to get the output adjustment of withdrawal rate (v (a key technological parameter. The multivariable fuzzy rule was built, based on the structure feature of casting, such as the relationship between section area, and the delay time of the temperature change response by changing v, and the professional experience of the operator as well. Then, the fuzzy controlling model coupled with CA-FD method could be used to optimize v in real-time during the manufacturing process. The optimized process was proven to be more flexible and adaptive for a steady and stray-grain free DS process.
The simulation and analysis of small group effect in crowd evacuation
You, Lei; Hu, Jun; Gu, Musong; Fan, Wenjie; Zhang, Hong
2016-10-01
A crowd usually tends to move in small groups during evacuation. Small group has a large proportion in crowd evacuation, and small group effect affects crowd evacuation significantly. In this work, we propose a novel methodology for calculating movement profit based on cellular automaton model. Specifically, this methodology calculates the movement profit for a target at the next moment by comprehensively combining distance profit, density profit, and average velocity profit. In particular, this paper defines three types of small-group formation with totally six different forms of small group in terms of the size, and sets the corresponding movement velocity. At last, we simulate the evacuation process of small groups, and discuss the relationship among evacuation time, average movement velocity, and pedestrian density, and analyze the efficiency of small group evacuation in terms of evacuation strategies. As the simulation results demonstrated, the evacuation efficiency of different types of small groups is greatly different, and the same type of small groups with different forms is also different.
A Novel Seven Input Majority Gate in Quantum-dot Cellular Automata
Directory of Open Access Journals (Sweden)
Keivan Navi
2012-01-01
Full Text Available A Quantum Cellular Automaton (QCA is a nanotechnology which is an attractive alternative for transistor based technologies in the near future. A new seven input majority gate in quantum dot cellular automata is proposed in this paper. The basic elements in QCA are majority and inverter gates, therefore using a majority gate with more inputs in QCA circuit will cause reduction in cell count, latency and complexity. Furthermore, by using the proposed seven input majority gate we can design four inputs AND gate and OR gate in only two clock phases. By applying these kinds of gates QCA circuits could be simplified and optimized. In order to prove the functionality of the proposed device, QCADesigner tool and some physical proofs are utilized.
Molecular dynamics simulation of ribosome jam
Matsumoto, Shigenori
2011-09-01
We propose a coarse-grained molecular dynamics model of ribosome molecules to study the dependence of translation process on environmental parameters. We found the model exhibits traffic jam property, which is consistent with an ASEP model. We estimated the influence of the temperature and concentration of molecules on the hopping probability used in the ASEP model. Our model can also treat environmental effects on the translation process that cannot be explained by such cellular automaton models. © 2010 Elsevier B.V. All rights reserved.
Institute of Scientific and Technical Information of China (English)
张浩
2015-01-01
针对车辆自组织网络（VANET）中由于相邻车辆会造成信号失真导致节点的高度移动性影响传输可靠性的问题，提出一种基于学习自动机建立虚拟退避算法的VANET介质访问算法。首先，借助于计数器共享的虚拟退避算法为每个节点分配一个计数器；然后，利用学习自动机确定指定节点序列号的最佳值；最后，使用RTS／CTS机制来奖惩每个节点以实现VBA介质访问。使用NS-2和MOVE进行的仿真实验验证了所提算法的有效性及可靠性，仿真结果表明，所提算法不仅改善了介质访问性能，而且节能效果明显，执行效果明显优于DCF和VBA等传统方案。%Adjacent vehicles will cause signal distortion in vehicular ad hoc networks (VANETs),which results in the transmission reliability being impacted by high mobility of nodes.Aiming at this problem,we propose a VANET medium access algorithm,it is based on setting up the virtual backoff algorithm (VBA)with learning automaton.First,the VBA by means of counter sharing allocates for every node a counter each.Then,it makes use of learning automaton to determine the optimum value of the specified node’s series number.Finally,it uses RTS/CTS mechanism to reward or punish each node to realise the medium access of VBA.The effectiveness and reliability of the proposed algorithm are verified by simulation experiment using NS-2 and MOVE.Simulation results show that the proposed algorithm improves the performance of medium access,and the energy saving effect is evident as well,its implementation effect is clearly better than traditional schemes of DCF and VBA.
Institute of Scientific and Technical Information of China (English)
匡文慧
2011-01-01
Dynamic urban expansion simulation at regional scale is one of the important research methodologies in Land Use/Cover Change (LUCC) and global environmental change influenced by urbanization. However, previous studies indicate that the single urban expansion simulation for future scenarios at local scale cannot meet the requirements for characterizing and interpreting the interactive mechanisms of regional urbanization and global environmental change. This study constructed a regional Dynamic Urban Expansion Model (Reg-DUEM) suitable for different scenarios by integrating the Artificial Neural Network (ANN) and Cellular Automaton (CA) model. Firstly we analyzed the temporal and spatial characteristics of urban expansion and acquired a prior knowledge rules using land use/cover change datasets of Beijing-Tianjin-Tangshan metropolitan area. The future urban expansion under different scenarios is then simulated based on a baseline model, economic models, policy models and the structural adjustment model. The results indicate that Reg-DUEM has good reliability for a non-linear expansion simulation at regional scale influenced by macro-policies. The simulating results show that future urban expansion patterns from different scenarios of the metropolitan area have the tremendous spatio-temporal differences. Future urban expansion will shift quickly from Beijing metropolis to the periphery of Tianjin and Tangshan city along coastal belt.
Efficient coarse simulation of a growing avascular tumor
Kavousanakis, Michail E.; Liu, Ping; Boudouvis, Andreas G.; Lowengrub, John; Kevrekidis, Ioannis G.
2013-01-01
The subject of this work is the development and implementation of algorithms which accelerate the simulation of early stage tumor growth models. Among the different computational approaches used for the simulation of tumor progression, discrete stochastic models (e.g., cellular automata) have been widely used to describe processes occurring at the cell and subcell scales (e.g., cell-cell interactions and signaling processes). To describe macroscopic characteristics (e.g., morphology) of growing tumors, large numbers of interacting cells must be simulated. However, the high computational demands of stochastic models make the simulation of large-scale systems impractical. Alternatively, continuum models, which can describe behavior at the tumor scale, often rely on phenomenological assumptions in place of rigorous upscaling of microscopic models. This limits their predictive power. In this work, we circumvent the derivation of closed macroscopic equations for the growing cancer cell populations; instead, we construct, based on the so-called “equation-free” framework, a computational superstructure, which wraps around the individual-based cell-level simulator and accelerates the computations required for the study of the long-time behavior of systems involving many interacting cells. The microscopic model, e.g., a cellular automaton, which simulates the evolution of cancer cell populations, is executed for relatively short time intervals, at the end of which coarse-scale information is obtained. These coarse variables evolve on slower time scales than each individual cell in the population, enabling the application of forward projection schemes, which extrapolate their values at later times. This technique is referred to as coarse projective integration. Increasing the ratio of projection times to microscopic simulator execution times enhances the computational savings. Crucial accuracy issues arising for growing tumors with radial symmetry are addressed by
Ngada, N M
2015-01-01
The complexity and cost of building and running high-power electrical systems make the use of simulations unavoidable. The simulations available today provide great understanding about how systems really operate. This paper helps the reader to gain an insight into simulation in the field of power converters for particle accelerators. Starting with the definition and basic principles of simulation, two simulation types, as well as their leading tools, are presented: analog and numerical simulations. Some practical applications of each simulation type are also considered. The final conclusion then summarizes the main important items to keep in mind before opting for a simulation tool or before performing a simulation.
Directory of Open Access Journals (Sweden)
Si-feng Gao
2015-03-01
Full Text Available The mechanism of stray grain formation at the platform of turbine blade simulator and the effect of withdrawal rate (V on the stray grain phenomenon have been investigated using a macro-scale ProCAST coupled with a 3D Cellular Automaton Finite Element (CAFE model. The results indicate that the stray grains nucleate at the edges of platform at V =150 μm·s-1 and 200 μm·s-1. Using ProCAST computer simulation software, it was proven that the stray grain formation is significantly dependent on the undercooling and the temperature field distribution in the platform. The macroscopic curvature of the liquidus isotherm becomes markedly concave with an increase in the withdrawal rate. The probability of stray grain formation at the edges of platform can be increased by increasing the withdrawal rate in the range of 70 μm·s-1 to 200 μm·s-1.
Institute of Scientific and Technical Information of China (English)
于群; 曹娜; 郭剑波
2011-01-01
将元胞自动机理论应用到电力系统大停电机理研究中,提出并建立了用元胞自动机来模拟电网故障演化的电网故障元胞自动机模型,定义了电网故障元胞自动机模型中元胞、元胞空间、规则和邻居等的构成方法。利用电网故障元胞自动机模型,仿真研究了电网故障的传播演化过程,并对电网故障的自组织临界性（SOC）进行了验证。%By applying the theory of cellular automata in the evolutionary mechanism of the power system blackout,a model for simulating power failure with cellular automata is presented.The model defines the composing method of cells,cellular space,rules,neighbors,etc.The spread and evolution of power failure is investigated using proposed model and the self-organized criticality（SOC） of the power grid failure is verified. This work is supported by State Administration of Work Safety Project（No.10-052） and State Grid Corporation of China.
Numerical Simulation of Dendritic Growth of Continuously Cast High Carbon Steel
Wang, Weiling; Luo, Sen; Zhu, Miaoyong
2015-01-01
Considering the influence of the latent heat released during the solidification of high carbon liquid steel, a cellular automaton (CA) model coupled with the heat transfer was developed to investigate the growth of equiaxed dendrites which is controlled by the solute diffusion during the continuous casting process. Additionally, the growth of columnar dendrites and primary dendrite arm spacings were predicted and measured. The results show that the CA model is able to describe the growth behavior of equiaxed dendrites, especially at 5 K to 7 K melt undercoolings, and the approach adjusting the cooling medium temperature is reliable to keep the undercooling condition stable for equiaxed dendrites although its hysteresis is reinforced as the pre-set undercooling increases. With the increase of the melt undercooling, the growth of equiaxed dendrites becomes faster, and the thickness of dendritic arms increases slightly, however, the thickness of the diffusion layer in front of dendritic tips keeps constant. The growth of thin and tiny columnar dendrites will be confined due to the competition and absorbed by neighboring strong columnar dendrites, giving rise to the coarsening of columnar dendrites, which is observed both from the experimental observation and the numerical simulation. With the decrease of the cooling intensity, columnar dendrites get sparser, primary dendrite arm spacings increase, and secondary dendritic arms become undeveloped.
Cellular: Toward personal communications
Heffernan, Stuart
1991-09-01
The cellular industry is one of the fastest growing segment of the telecommunications industry. With an estimated penetration rate of 20 percent in the near future, cellular is becoming an ubiquitous telecommunications service in the U.S. In this paper we will examine the major advancements in the cellular industry: customer equipment, cellular networks, engineering tools, customer support, and nationwide seamless service.
Obade, P.; Koedam, N.; Soetaert, K.E.R.; Neukermans, G.; Bogaert, J.; Nyssen, E.; van Nedervelde, F.; Berger, U.; Dahdouh-Guebas, F.
2009-01-01
Mangrove forests are ecologically and economically important and frequently dominating protected coastal areas in the tropics and subtropics at suitable intertidal zones and are often subjected to disturbances that disrupt the structure of an ecosystem, that change resource availability and that cre
Matthew W. Johnston; Sam J Purkis
2013-01-01
The Indo-pacific panther grouper (Chromileptes altiveli) is a predatory fish species and popular imported aquarium fish in the United States which has been recently documented residing in western Atlantic waters. To date, the most successful marine invasive species in the Atlantic is the lionfish (Pterois volitans/miles), which, as for the panther grouper, is assumed to have been introduced to the wild through aquarium releases. However, unlike lionfish, the panther grouper is not yet thought...
Energy Technology Data Exchange (ETDEWEB)
Rojas C, E. L.; Avila, O., E-mail: leticia.rojas@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)
2012-10-15
In this work the simulation codes Monte Carlo, Penelope and MCNPX were used to calculate the doses by unit of accumulated activity S(N-N) in water spherical cells models of different radius exposed to mono-energetics electrons coming from punctual sources located in the center of the cellular nucleus. The studied cellular radii were: r{sub n}1=3 r{sub c}1=6; r{sub n}2=5 and r{sub c}2=10; r{sub n}3=9 and r{sub c}3=10 {mu}m; being r{sub n} and r{sub c} the nuclear and cellular radius, respectively. The following initial energies of the electrons were considered: 1, 5, 10, 50, 100, 500, 700 and 1000 keV. Additionally values S(N-N) were calculated for spherical cells of r= 3 {mu}m r{sub c}= 6 {mu}m due to the electrons coming from sources of {sup 111}In, {sup 177}Lu, {sup 99m}Tc, {sup 188}Re and {sup 186}Re. The obtained values are compared with those calculated by the MIRD Committee internationally accepted. The percentage differences between the values reported by this Committee and those calculated by Monte Carlo simulation are inside the interval that is considered valid for this dosimetry type. A major concordance was found among the values calculated by Monte Carlo simulation that among those calculated by MIRD and those obtained by simulation. Considering validated the use of both codes for similar applications, the values S(N-N) and S(N-C y) were obtained of prostate cancer real cells models of the PC3 line. The results were compared among them. The values of S(N-N) obtained with Penelope for the PC3 cells for the electron emissions of {sup 111}In, {sup 177}Lu, {sup 99m}Tc, {sup 188}Re and {sup 186}Re are: 3.19e{sup {sub {sup 4}}}, 3.24e{sup -4}, 1.37e{sup -4}, 1.11e{sup -4} and 1.91e{sup -4} Gy/Bq-s, respectively. Also the obtained results for S(N-C y) are: 2.95e{sup -6}, 3.17e{sup -5}, 2.09e{sup -6}, 1.41e{sup -5}, 1.86e{sup -5} Gy/Bq-s. (Author)
Ander, M; Beltrao, P; Di Ventura, B; Ferkinghoff-Borg, J; Foglierini, M; Kaplan, A; Lemerle, C; Tomás-Oliveira, I; Serrano, L
2004-06-01
SmartCell has been developed to be a general framework for modelling and simulation of diffusion-reaction networks in a whole-cell context. It supports localisation and diffusion by using a mesoscopic stochastic reaction model. The SmartCell package can handle any cell geometry, considers different cell compartments, allows localisation of species, supports DNA transcription and translation, membrane diffusion and multistep reactions, as well as cell growth. Moreover, different temporal and spatial constraints can be applied to the model. A GUI interface that facilitates model making is also available. In this work we discuss limitations and advantages arising from the approach used in SmartCell and determine the impact of localisation on the behaviour of simple well-defined networks, previously analysed with differential equations. Our results show that this factor might play an important role in the response of networks and cannot be neglected in cell simulations.
Experimental and Numerical Simulations of the Solidification Process in Continuous Casting of Slab
Directory of Open Access Journals (Sweden)
Liang Bai
2016-03-01
Full Text Available Thermal simulation equipment (TSE was recently developed to simulate the solidification process in the industrial continuous casting of slab. The grain growth, solid-liquid interface movement, and columnar-to-equiaxed transition (CET in the continuous casting process can be reproduced using this equipment. The current study is focused on the effects of different cooling rates and superheat conditions on the grain growth in the solidification process of chromium-saving ferritic stainless steel (B425. The temperature distribution and microstructure evolution are simulated by a Cellular Automaton-Finite Element (CAFE model. The experimental results demonstrate that the temperature gradient and the grain growth rate of the sample can be effectively controlled by the equipment. It is observed from optical micrographs of the microstructure that the average equiaxed grain ratio increases when the superheat temperature decreases. The average equiaxed grain ratio is approximately 26% and 42% under superheat conditions of 40 °C and 30 °C, respectively, and no apparent columnar grain generation in the samples occurs under superheat conditions of 10 °C and 20 °C, as the result of a large thermal resistance at the copper-sample interface and low superheat inside the sample. A lower cooling rate results in a higher equiaxed crystal ratio in the sample. As the cooling rate decreases, the equiaxed crystal ratio becomes 14%, 23%, and 42%. Comparing the simulation results with the experimental observations, a reasonable qualitative agreement is achieved for the chilled layer thickness, grain morphology, and CET in the sample. Thus, the CAFE model in the current study can accurately predict the grain growth under different superheating and cooling rate conditions.
Stylized Facts Generated Through Cellular Automata Models. Case of Study: The Game of Life
Coronel-Brizio, H F; Rodriguez-Achach, M E; Stevens-Ramirez, G A
2007-01-01
In the present work, a geometrical method to generate a two dimensional random walk by means of a bidimensional Cellular Automaton is presented. We illustrate it by means of Conway's Game of Life with periodical borders, with a large lattice of 3000 x 3000 cells. The obtained random walk is of character anomalous, and its projection to a one dimensional random walk is analyzed, showing that it presents some statistical properties similar to the so-called stylized facts observed in financial time series. We consider that the procedure presented here is important not only because of its simplicity, but also because it could help us to understand and shed light on the stylized facts formation mechanism.
Directory of Open Access Journals (Sweden)
M. Górny
2012-12-01
Full Text Available The mathematical model of the globular eutectic solidification in 2D was designed. Proposed model is based on the Cellular AutomatonFinite Differences (CA-FD calculation method. Model has been used for studies of the primary austenite and of globular eutectic grainsgrowth during the ductile iron solidification in the thin wall casting. Model takes into account, among other things, non-uniformtemperature distribution in the casting wall cross-section, kinetics of the austenite and graphite grains nucleation, and non-equilibriumnature of the interphase boundary migration. Calculation of eutectic saturation influence (Sc = 0.9 - 1.1 on microstructure (austenite and graphite fraction, density of austenite and graphite grains and temperature curves in 2 mm wall ductile iron casting has been done.
Two-material optimization of plate armour for blast mitigation using hybrid cellular automata
Goetz, J.; Tan, H.; Renaud, J.; Tovar, A.
2012-08-01
With the increased use of improvised explosive devices in regions at war, the threat to military and civilian life has risen. Cabin penetration and gross acceleration are the primary threats in an explosive event. Cabin penetration crushes occupants, damaging the lower body. Acceleration causes death at high magnitudes. This investigation develops a process of designing armour that simultaneously mitigates cabin penetration and acceleration. The hybrid cellular automaton (HCA) method of topology optimization has proven efficient and robust in problems involving large, plastic deformations such as crash impact. Here HCA is extended to the design of armour under blast loading. The ability to distribute two metallic phases, as opposed to one material and void, is also added. The blast wave energy transforms on impact into internal energy (IE) inside the solid medium. Maximum attenuation occurs with maximized IE. The resulting structures show HCA's potential for designing blast mitigating armour structures.
McCoy, Sophie J; Allesina, Stefano; Pfister, Catherine A
2016-03-16
Historical ecological datasets from a coastal marine community of crustose coralline algae (CCA) enabled the documentation of ecological changes in this community over 30 years in the Northeast Pacific. Data on competitive interactions obtained from field surveys showed concordance between the 1980s and 2013, yet also revealed a reduction in how strongly species interact. Here, we extend these empirical findings with a cellular automaton model to forecast ecological dynamics. Our model suggests the emergence of a new dominant competitor in a global change scenario, with a reduced role of herbivory pressure, or trophic control, in regulating competition among CCA. Ocean acidification, due to its energetic demands, may now instead play this role in mediating competitive interactions and thereby promote species diversity within this guild. PMID:26936244
Cellular Cell Bifurcation of Cylindrical Detonations
Institute of Scientific and Technical Information of China (English)
HAN Gui-Lai; JIANG Zong-Lin; WANG Chun; ZHANG Fan
2008-01-01
Cellular cell pattern evolution of cylindrically-diverging detonations is numerically simulated successfully by solving two-dimensional Euler equations implemented with an improved two-step chemical kinetic model. From the simulation, three cell bifurcation modes are observed during the evolution and referred to as concave front focusing, kinked and wrinkled wave front instability, and self-merging of cellular cells. Numerical research demonstrates that the wave front expansion resulted from detonation front diverging plays a major role in the cellular cell bifurcation, which can disturb the nonlinearly self-sustained mechanism of detonations and finally lead to cell bifurcations.
A Proliferation of Air Pollution Simulation System base on Cellular Automata%基于元胞自动机的污染气体扩散模拟系统
Institute of Scientific and Technical Information of China (English)
秦弋丰; 杨雨诚; 谢育武; 李俚; 吴皆强
2015-01-01
元胞自动机模型( Cellular Automation Model, CA模型)是一种用于模拟离散动力系统内部的各独立单元间因为强烈非线性作用而引发的系统自组织演化过程的建模方式,规则的局部性和时空离散化是CA模型的主要特征.本系统基于当今城市最为严重的空气污染问题展开研究,主要通过在地图上确定污染源位置,并录入污染源数据,通过元胞自动机原理,模拟在有风和无风状态下污染气体元胞的运动状况,从微观到宏观,系统地描述污染气体的运动状况.%Cellular Automation Model(CA) is a modeling method used to simulate the internal unit between discrete dynamic system that caused the evolution of a self-organization in system because of nonlinear function. Temporal discretization and local rule is it main feature. We developed this system according to the one of the most serious problems of our city in these days which is air pollution. By pain point the source of pollution on the map and input the pollution data, through the principle of the Cellular automata, stimulated the movement of pollution gas cell under condition of both windy calm. Describe the motion of the pollution gas from micro to macro.
Stochastic Nature in Cellular Processes
Institute of Scientific and Technical Information of China (English)
刘波; 刘圣君; 王祺; 晏世伟; 耿轶钊; SAKATA Fumihiko; GAO Xing-Fa
2011-01-01
The importance of stochasticity in cellular processes is increasingly recognized in both theoretical and experimental studies. General features of stochasticity in gene regulation and expression are briefly reviewed in this article, which include the main experimental phenomena, classification, quantization and regulation of noises. The correlation and transmission of noise in cascade networks are analyzed further and the stochastic simulation methods that can capture effects of intrinsic and extrinsic noise are described.
DEFF Research Database (Denmark)
Gould, Derek A; Chalmers, Nicholas; Johnson, Sheena J;
2012-01-01
Recognition of the many limitations of traditional apprenticeship training is driving new approaches to learning medical procedural skills. Among simulation technologies and methods available today, computer-based systems are topical and bring the benefits of automated, repeatable, and reliable...... performance assessments. Human factors research is central to simulator model development that is relevant to real-world imaging-guided interventional tasks and to the credentialing programs in which it would be used....
Wituszynska, Weronika; Slesak, Ireneusz; Vanderauwera, Sandy; Szechynska-Hebda, Magdalena; Kornas, Andrzej; Van Der Kelen, Katrien; Mühlenbock, Per; Karpinska, Barbara; Mackowski, Sebastian; Van Breusegem, Frank; Karpinski, Stanislaw
2013-04-01
There is growing evidence that for a comprehensive insight into the function of plant genes, it is crucial to assess their functionalities under a wide range of conditions. In this study, we examined the role of lesion simulating disease1 (LSD1), enhanced disease susceptibility1 (EDS1), and phytoalexin deficient4 (PAD4) in the regulation of photosynthesis, water use efficiency, reactive oxygen species/hormonal homeostasis, and seed yield in Arabidopsis (Arabidopsis thaliana) grown in the laboratory and in the field. We demonstrate that the LSD1 null mutant (lsd1), which is known to exhibit a runaway cell death in nonpermissive conditions, proves to be more tolerant to combined drought and high-light stress than the wild type. Moreover, depending on growing conditions, it shows variations in water use efficiency, salicylic acid and hydrogen peroxide concentrations, photosystem II maximum efficiency, and transcription profiles. However, despite these changes, lsd1 demonstrates similar seed yield under all tested conditions. All of these traits depend on EDS1 and PAD4. The differences in the pathways prevailing in the lsd1 in various growing environments are manifested by the significantly smaller number of transcripts deregulated in the field compared with the laboratory, with only 43 commonly regulated genes. Our data indicate that LSD1, EDS1, and PAD4 participate in the regulation of various molecular and physiological processes that influence Arabidopsis fitness. On the basis of these results, we emphasize that the function of such important regulators as LSD1, EDS1, and PAD4 should be studied not only under stable laboratory conditions, but also in the environment abounding in multiple stresses.
Institute of Scientific and Technical Information of China (English)
寇勇刚; 吴桐水; 朱金福
2011-01-01
In order to research the role of airlines service innovation in the competition of the aviation market, the competition model of aviation service innovation is built up with cellular automata. Taken one of Shenzhen Airlinees' Shenzhen to Beijing flight in 2008 as an example, satisfied result have acquired by repeated experiments of simulation to the innovational cabin service evolution during the competition. The research conclusion shows that there are three factors which include the initial data of cellular automata,the service fitness and the sales promotion,all of the three effect the evolutional mutation period and make it into positive trend. Meanwhile, the role of the three factors become decreasing while the parameter of them gradually increasing.%为研究航空公司服务创新在市场竞争中的作用,基于元胞自动机设计了航空服务创新竞争模型.以深航2008年在深圳-北京航线上推出服务创新为例,经过重复试验较好地模拟了在该航线上进行服务创新取得成功的竞争演化过程.研究结果表明:初始接受服务创新的元胞数量、服务匹配度和品牌宣传效应度三个影响因素都对演化的突变周期起正向影响作用,且三个因素对突变周期的正向作用随着取值的增大而逐渐减弱.
Institute of Scientific and Technical Information of China (English)
陈晨; 陈建桥
2011-01-01
According to the theory of cellular automata ( CA), the urban traffic flows at 4 intersections were investigated and a set of discrete equations were proposed to describe the traffic dynamics. The effect of two signal control strategies, i.e., synchronous timing control and actuated control, on traffic flow were discussed. Simulation results show that ( 1 ) the effect of signal control strategies is related to the density of traffic flow; (2) and there exists a certain range of actuated control parameters in which the efficiency of traffic flow can be optimized. Therefore, in order to ensure the efficiency of traffic flow, one the proper signal control strategy should be chosen for different global densities of traffic flow.%采用细胞自动机方法(Cellular Automata:CA)模拟含4个路口的城市道路交通流状态,并通过离散方程描述车辆的运动过程.研究了信号灯控制策略(同步定时控制及感应控制)对交通流状态的影响.数值模拟结果表明,信号灯对交通流的影响与道路中车辆密度有关,同时,感应控制参数的选取存在一合理的取值范围,可优化交通流通行效率.因此,为保证交通流的通行效率,应针对不同的车辆密度,选取适当的信号灯控制方式.
The Universe as a Cellular System
Aragón-Calvo, Miguel A
2014-01-01
Cellular systems are observed everywhere in nature, from crystal domains in metals, soap froth and cucumber cells to the network of cosmological voids. Surprisingly, despite their disparate scale and origin all cellular systems follow certain scaling laws relating their geometry, topology and dynamics. Using a cosmological N-body simulation we found that the Cosmic Web, the largest known cellular system, follows the same scaling relations seen elsewhere in nature. Our results extend the validity of scaling relations in cellular systems by over 30 orders of magnitude in scale with respect to previous studies. The dynamics of cellular systems can be used to interpret local observations such as the local velocity anomaly as the result of a collapsing void in our cosmic backyard. Moreover, scaling relations depend on the curvature of space, providing an independent measure of geometry.
Ross, Sheldon
2006-01-01
Ross's Simulation, Fourth Edition introduces aspiring and practicing actuaries, engineers, computer scientists and others to the practical aspects of constructing computerized simulation studies to analyze and interpret real phenomena. Readers learn to apply results of these analyses to problems in a wide variety of fields to obtain effective, accurate solutions and make predictions about future outcomes. This text explains how a computer can be used to generate random numbers, and how to use these random numbers to generate the behavior of a stochastic model over time. It presents the statist
International Nuclear Information System (INIS)
Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc
Energy Technology Data Exchange (ETDEWEB)
Roentzsch, L.
2007-07-01
Single-crystalline nanostructures often exhibit gradients of surface (and/or interface) curvature that emerge from fabrication and growth processes or from thermal fluctuations. Thus, the system-inherent capillary force can initiate morphological transformations during further processing steps or during operation at elevated temperature. Therefore and because of the ongoing miniaturization of functional structures which causes a general rise in surface-to-volume ratios, solid-state capillary phenomena will become increasingly important: On the one hand diffusion-mediated capillary processes can be of practical use in view of non-conventional nanostructure fabrication methods based on self-organization mechanisms, on the other hand they can destroy the integrity of nanostructures which can go along with the failure of functionality. Additionally, capillarity-induced shape transformations are effected and can thereby be controlled by applied fields and forces (guided or driven evolution). With these prospects and challenges at hand, formation and shape transformation of single-crystalline nanostructures due to the system-inherent capillary force in combination with external fields or forces are investigated in the frame of this dissertation by means of atomistic computer simulations. For the exploration (search, description, and prediction) of reaction pathways of nanostructure shape transformations, kinetic Monte Carlo (KMC) simulations are the method of choice. Since the employed KMC code is founded on a cellular automaton principle, the spatio-temporal development of lattice-based N-particle systems (N up to several million) can be followed for time spans of several orders of magnitude, while considering local phenomena due to atomic-scale effects like diffusion, nucleation, dissociation, or ballistic displacements. In this work, the main emphasis is put on nanostructures which have a cylindrical geometry, for example, nanowires (NWs), nanorods, nanotubes etc
Institute of Scientific and Technical Information of China (English)
覃松; 邓敏艺; 孔令江
2011-01-01
In order to study the influences of margin financing, as well as how to relieve the impact of short selling system,modeling theory and method using cellular automata are applied to establish a single stock automata model. In this paper,simulations of trading volume and price fluctuation before and after the introduction of margin financing business are carried out. Simulation results show that the release of new margin financing can increase trading volume and stabalize trading price more easily,and it may help to increase the fluctuation of the trading price. The advices about relieving the impact of short selling system are helpful to financial supervision departments in maintaining market stability.%为研究融资融券推出对股票市场带来的影响以及如何减少融券卖空对市场的冲击,建立基于元胞自动机的股票市场模型,对融资融券推出前后的股票交易量和价格波动进行计算机仿真.仿真结果表明,融资融券的推出既可能增加股票市场的交易量,有利于市场内在价格稳定机制形成,也可能对价格助涨助跌,增大市场的波动.本文还针对融券卖空的潜在风险提出规避建议,这对相关金融部门保障市场稳定运行具有一定借鉴意义.
Energy Technology Data Exchange (ETDEWEB)
Ahmad, S. [University of Kashmir, Srinagar (India); Bhaduri, P.P. [Variable Energy Cyclotron Centre, Kolkata (India); Jahan, H. [Aligarh Muslim University, Aligarh (India); Senger, A. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Adak, R.; Samanta, S. [Bose Institute, Kolkata (India); Prakash, A. [Banaras Hindu University, Varanasi (India); Dey, K. [Gauhati University, Guwahati (India); Lebedev, A. [Institute für Kernphysik, Goethe Universität Frankfurt, Frankfurt (Germany); Kryshen, E. [Petersburg Nuclear Physics Institute (PNPI) NRC Kurchatov Institute, Gatchina (Russian Federation); Chattopadhyay, S., E-mail: sub@vecc.gov.in [Variable Energy Cyclotron Centre, Kolkata (India); Senger, P. [GSI Helmholtzzentrum fur Schwerionenforschung GmbH, Darmstadt (Germany); Bhattacharjee, B. [Gauhati University, Guwahati (India); Ghosh, S.K.; Raha, S. [Bose Institute, Kolkata (India); Irfan, M.; Ahmad, N. [Aligarh Muslim University, Aligarh (India); Farooq, M. [University of Kashmir, Srinagar (India); Singh, B. [Banaras Hindu University, Varanasi (India)
2015-03-01
A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)
International Nuclear Information System (INIS)
A muon detection system (MUCH) based on a novel concept using a segmented and instrumented absorber has been designed for high-energy heavy-ion collision experiments. The system consists of 6 hadron absorber blocks and 6 tracking detector triplets. Behind each absorber block a detector triplet is located which measures the tracks of charged particles traversing the absorber. The performance of such a system has been simulated for the CBM experiment at FAIR (Germany) that is scheduled to start taking data in heavy ion collisions in the beam energy range of 6–45 A GeV from 2019. The muon detection system is mounted downstream to a Silicon Tracking System (STS) that is located in a large aperture dipole magnet which provides momentum information of the charged particle tracks. The reconstructed tracks from the STS are to be matched to the hits measured by the muon detector triplets behind the absorber segments. This method allows the identification of muon tracks over a broad range of momenta including tracks of soft muons which do not pass through all the absorber layers. Pairs of oppositely charged muons identified by MUCH could therefore be combined to measure the invariant masses in a wide range starting from low mass vector mesons (LMVM) up to charmonia. The properties of the absorber (material, thickness, position) and of the tracking chambers (granularity, geometry) have been varied in simulations of heavy-ion collision events generated with the UrQMD generator and propagated through the setup using the GEANT3, the particle transport code. The tracks are reconstructed by a Cellular Automaton algorithm followed by a Kalman Filter. The simulations demonstrate that low mass vector mesons and charmonia can be clearly identified in central Au+Au collisions at beam energies provided by the international Facility for Antiproton and Ion Research (FAIR)
Heterogeneous cellular networks
Hu, Rose Qingyang
2013-01-01
A timely publication providing coverage of radio resource management, mobility management and standardization in heterogeneous cellular networks The topic of heterogeneous cellular networks has gained momentum in industry and the research community, attracting the attention of standardization bodies such as 3GPP LTE and IEEE 802.16j, whose objectives are looking into increasing the capacity and coverage of the cellular networks. This book focuses on recent progresses, covering the related topics including scenarios of heterogeneous network deployment, interference management i
Extraction of text content from PDF documents based on automaton theory%基于自动机理论的PDF文本内容抽取
Institute of Scientific and Technical Information of China (English)
王晓娟; 谭建龙; 刘燕兵; 刘金刚
2012-01-01
现有的从PDF文档抽取文本内容的方法(如PDFBox类库采用的方法)处理速度较低,无法满足高速网络中内容分析的需求,也不能对网络中部分到达的PDF数据包进行流式的处理.为此,提出了基于自动机理论的PDF文本内容抽取方法.该方法通过建立具有层次的关键字自动机,可以快速地抽取完整PDF文档和不完整PDF文档中的文本内容.在中文和英文PDF文档数据集下的实验结果表明,基于自动机理论的PDF文本内容抽取方法耗时仅为PDFBox方法的17％ ～37％.%The existing methods of extracting text content from a PDF file, such as the one adopted by the PDFBox library, are not efficient enough to handle the high-speed network traffic. Moreover, these methods cannot extract the contents streamingly from partial PDF packets in transfer. This paper proposed a new method based on automaton theory. The method adopted a hierarchical keyword Deterministic Finite Automaton (DFA) to extract information from complete or incomplete PDF files. The experimental results show that the response time of the proposed method is about 17% - 37% of the algorithm used by PDFBox when processing PDF files in Chinese or English.
Nanostructured cellular networks.
Moriarty, P; Taylor, M D R; Brust, M
2002-12-01
Au nanocrystals spin-coated onto silicon from toluene form cellular networks. A quantitative statistical crystallography analysis shows that intercellular correlations drive the networks far from statistical equilibrium. Spin-coating from hexane does not produce cellular structure, yet a strong correlation is retained in the positions of nanocrystal aggregates. Mechanisms based on Marangoni convection alone cannot account for the variety of patterns observed, and we argue that spinodal decomposition plays an important role in foam formation.
Cellular Cardiomyoplasty: Clinical Application
Chachques, J. (J.); Acar, C; J. Herreros; Trainini, J. (Jorge); Prosper, F.; D’Attellis, N. (N.); Fabiani, J. N.; Carpentier, A
2004-01-01
Myocardial regeneration can be induced with the implantation of a variety of myogenic and angiogenic cell types. More than 150 patients have been treated with cellular cardiomyoplasty worldwide, 18 patients have been treated by our group. Cellular cardiomyoplasty seems to reduce the size and fibrosis of infarct scars, limit postischemic remodelling, and restore regional myocardial contractility. Techniques for skeletal myoblasts culture and ex vivo expansion using auto...
Cellular automata modelling of SEIRS
Institute of Scientific and Technical Information of China (English)
Liu Quan-Xing; Jin Zhen
2005-01-01
In this paper the SEIRS epidemic spread is analysed, and a two-dimensional probability cellular automata model for SEIRS is presented. Each cellular automation cell represents a part of the population that may be found in one of five states of individuals: susceptible, exposed (or latency), infected, immunized (or recovered) and death. Here studied are the effects of two cases on the epidemic spread. i.e. the effects of non-segregation and segregation on the latency and the infected of population. The conclusion is reached that the epidemic will persist in the case of non-segregation but it will decrease in the case of segregation. The proposed model can serve as a basis for the development of algorithms to simulate real epidemics based on real data. Last we find the density series of the exposed and the infected will fluctuate near a positive equilibrium point, when the constant for the immunized is less than its corresponding constant τ0. Our theoretical results are verified by numerical simulations.
Benchmark study between FIDAP and a cellular automata code
Akau, R. L.; Stockman, H. W.
A fluid flow benchmark exercise was conducted to compare results between a cellular automata code and FIDAP. Cellular automata codes are free from gridding constraints, and are generally used to model slow (Reynolds number approximately 1) flows around complex solid obstacles. However, the accuracy of cellular automata codes at higher Reynolds numbers, where inertial terms are significant, is not well-documented. In order to validate the cellular automata code, two fluids problems were investigated. For both problems, flow was assumed to be laminar, two-dimensional, isothermal, incompressible and periodic. Results showed that the cellular automata code simulated the overall behavior of the flow field.
Cellular automata modeling of pedestrian's crossing dynamics
Institute of Scientific and Technical Information of China (English)
张晋; 王慧; 李平
2004-01-01
Cellular automata modeling techniques and the characteristics of mixed traffic flow were used to derive the 2-dimensional model presented here for simulation of pedestrian's crossing dynamics.A conception of "stop point" is introduced to deal with traffic obstacles and resolve conflicts among pedestrians or between pedestrians and the other vehicles on the crosswalk.The model can be easily extended,is very efficient for simulation of pedestrian's crossing dynamics,can be integrated into traffic simulation software,and has been proved feasible by simulation experiments.
基于元胞自动机模型的开采沉陷模拟%Simulation of Coal Mining Subsidence Based on the Model of Cellular Automata
Institute of Scientific and Technical Information of China (English)
陈秋计
2013-01-01
The simulation of mining subsidence plays an important role in mining environmental management and ecological restoration. Based on the GIS platform, the mining subsidence theory and geographical Cellular Automata (CA) are combined with each other, and then the mining subsidence cellular space is constructed by using the development tool of object-oriented method with the help of software of VS2010. The mining subsidence frame structure of CA model and realization method is discussed, and the mining subsidence simulation object relation graph is constructed. The evolution model of CA for mining subsidence is established based on the research result. Finally, the prototype system of mining subsidence CA is developed by taking a coal mine in Shanxi Province as an example. Based on the coal seam condition and mining method of the study area, the evolution of mining subsidence in the future is simulated usi ng the prototype system in order to provide the basis for land reclamation and ecological restoration. The results show that object-oriented method is good for the analysis and exploitation of mining subsidence simulation system, and mining subsidence simulation based on GIS and CA, which is facilitated to the development of the system and has good compatibility, is able to show more spatiotemporal information, facilitating data management. In space division, the CA model could organically integrate into traditional method, and is able to accurately predict the future of surface subsidence damage, providing the basis for the treatment for subsidence area. Since mining subsidence relates to many subjects, there are many works need to be down in the future for further perfecting evolution model, exploring the evolution process of system in three-dimensional space, and enhancing the reality and practicability of simulation.%开采沉陷模拟对矿区的环境治理和生态恢复具有重要意义.本文将开采沉陷理论与地理元胞自动
城市交通拥堵的经济学分析和元胞自动机模拟%Economic Analysis of Urban Traffic Congestion and Cellular Automata Simulation
Institute of Scientific and Technical Information of China (English)
李捷; 朱明皓
2011-01-01
分析了城市道路系统的公共性和外部性.使用均衡分析的方法对城市交通拥堵进行了经济学分析,认为当城市道路的使用者超过一定数量时,道路交通的外部性凸显出来,由于这种外部性,道路交通系统总数处于过度使用的状态.最后使用元胞自动机对城市交通拥堵现象进行了模拟,发现为了改善城市交通堵塞,虽然需要增加交通供给,但是更为重要的是如何优化车流使得现有的交通供给得到充分的利用.%This paper discusses the economic characteristics of urban road traffic system, analyzes the public and external nature of the urban road system. Using the method of equilibrium analysis, the paper gives an economic analysis of urban traffic congestion and finds that the urban road traffic system shows externality when the number of road users reach a certain threshold. Because of this externality, the urban road traffic system is constantly in the state of excessive use. Finally, the article uses cellular automata to simulate the urban traffic congestion phenomenon and finds that, to improve urban traffic congestion, necessary as it is to increase the supply of urban road traffic system, what is more important is to figure out how to optimize traffic flow to make existing supply fully utilized.
Institute of Scientific and Technical Information of China (English)
刘天卓; 孙伟然; 杨靖
2011-01-01
在企业所面临的不同类型的危机中，产品质量危机所占的比重最大。本文从群体行为的角度研究企业产品质量危机的形成机理，利用元胞自动机的定性模拟理论和方法，建立消费者对产品的购买行为的演化模型，通过基于不同的从众系数和演化规则的演化，揭示群体从众行为与企业危机公关与企业产品质量危机的形成之间的关系，并在此基础上提出了基于消费者信任修复理论的管理思路，对现代企业的危机管理有一定的借鉴与指导意义。%In modem society, exigencies happen frequently, and if not handled properly in the incident, the influence that does not digest and relieve the crisis will result in formation. In the different types of crisis the corporation faced, the most proportion is product quality crisis. We research the formation mechanism of enterprise manufacture crisis from the point of group behaviour, utilize the theory and method of qualitative simulation of cellular automata, build the buying behaviour evolution model of customers, by the evolution based different conformity ratio and evolution rule, reveal the relationship between the group behaviour and business crisis public relation and enterprise production crisis, and based on that we propose management thread based on the consumer confidence restore model, which can guide the crisis management for companies.
Institute of Scientific and Technical Information of China (English)
冒玉婷; 邓建华
2015-01-01
An improved cellular automata model considering demand space is proposed to simulate bidirectional pedestrian flow based on NS model . New model incorporates a social distance to describe territorial effects between pedestrians and to avoid the conflicts in advance . In order to display the attraction between synthetic pedestrians , this model also considered the vision field that allows a pedestrian to collect information from cells in front of him/her and also to get the weighted demand parameter .Through Matlab simulation ,the velocity‐density diagram is obtained .Comparing the result with social model and Weidmann diagram ,we can see that new model can avoid the conflicts in advance effectively and the overall average speed has increased . Besides ,the presented model can reproduce Weidmann within the range of 0~5 p/m2 .%在NS模型的基础上提出考虑需求空间的双向行人交通流仿真模型。新模型采用需求空间来描述行人之间一定区域内的相互影响，提前避免冲突的发生。为更好地描述同向行人之间的吸引力，模型还考虑视野邻域以收集行人视野范围内的交通信息从而得到加权社会参数值。通过M atlab对改进的模型进行仿真，将仿真实验所得的流密图与Weidmann基本图和社会力模型比较，结果表明：新模型有效地提前避免冲突，行人流整体速度有所提高；行人密度在0～5 p／m2区间变化时能够再现Weidmann基本图。
Institute of Scientific and Technical Information of China (English)
马世发; 艾彬; 赵克飞
2014-01-01
Geography simulation model such as Cellular Automata (CA) is one of the most important tools for simulating and early warning the urban growth. The CA model can simulate urban sprawling accurately only when suitable conversion rules for every cell are achieved. Hence, the core of CA is to derive the conversion rules, and many researchers have been interested in discovering the rules. However, the conversion rules of tradi-tional CA are mainly derived from historic samples, in which both changed samples and unchanged ones are con-sidered for function fitting to retrieve parameters simultaneously. In this approach, it is assumed that if the urban sprawling occurred, samples were labeled as 1; otherwise, samples were accordingly labeled as 0. However, it will result in over fitting for the unchanged samples, because those samples with labels of 0 may have the potenti-ality to transform in future, especially for those located at the rural-urban fringe. Therefore, we proposed a gradi-ent CA for simulating urban sprawling. In this model, whether or not urban growth would occur was determined by the developing probability instead of its developed or undeveloped status. Accordingly, the unchanged sam-ples were set to the values ranging from 0 to 1. And in this research, the developing potentiality was estimated ac-cording to present planning maps. Compared with traditional CA, the gradient CA could avoid the over fitting problem for the unchanged samples to a certain degree. Moreover, the fitting objective was distinguished from traditional CA for its ability in retrieving conversion rules. In addition, particle swarm optimization algorithm was used to obtain the parameters of spatial indices. Finally, Guangzhou City, which locates in the Pearl River Delta of China, was chosen as the study area for model implementation and validation. In this case study, the spa-tial developing potentiality was allocated referring to the major function zone (MFZ) planning, because MFZ is
Energy Technology Data Exchange (ETDEWEB)
Cirioni, L.; Patau, J.P.; Nepveu, F. [Universite Paul Sabatier, 31 - Toulouse (France)
1998-04-01
A Monte Carlo code is developed to study the action of particles in Boron Neutron Capture Therapy (BNCT). Our aim is to calculate the probability of dissipating a lethal dose in cell nuclei. Cytoplasmic and nuclear membranes are considered as non-concentric ellipsoids. All geometrical parameters may be adjusted to fit actual configurations. The reactions {sup 10}B(n,{gamma} {alpha}){sup 7}Li and {sup 14}N(n,p) {sup 14}C create heavy ions which slow clown losing their energy. Their trajectories can be simulated taking into account path length straggling. The contribution of each reaction to the deposited dose in different cellular compartments can be studied and analysed for any distribution of {sup 10}B. (authors)
Modeling cellular deformations using the level set formalism
Directory of Open Access Journals (Sweden)
Yang Liu
2008-07-01
Full Text Available Abstract Background Many cellular processes involve substantial shape changes. Traditional simulations of these cell shape changes require that grids and boundaries be moved as the cell's shape evolves. Here we demonstrate that accurate cell shape changes can be recreated using level set methods (LSM, in which the cellular shape is defined implicitly, thereby eschewing the need for updating boundaries. Results We obtain a viscoelastic model of Dictyostelium cells using micropipette aspiration and show how this viscoelastic model can be incorporated into LSM simulations to recreate the observed protrusion of cells into the micropipette faithfully. We also demonstrate the use of our techniques by simulating the cell shape changes elicited by the chemotactic response to an external chemoattractant gradient. Conclusion Our results provide a simple but effective means of incorporating cellular deformations into mathematical simulations of cell signaling. Such methods will be useful for simulating important cellular events such as chemotaxis and cytokinesis.
Epigenetics and Cellular Metabolism
Xu, Wenyi; Wang, Fengzhong; Yu, Zhongsheng; Xin, Fengjiao
2016-01-01
Living eukaryotic systems evolve delicate cellular mechanisms for responding to various environmental signals. Among them, epigenetic machinery (DNA methylation, histone modifications, microRNAs, etc.) is the hub in transducing external stimuli into transcriptional response. Emerging evidence reveals the concept that epigenetic signatures are essential for the proper maintenance of cellular metabolism. On the other hand, the metabolite, a main environmental input, can also influence the processing of epigenetic memory. Here, we summarize the recent research progress in the epigenetic regulation of cellular metabolism and discuss how the dysfunction of epigenetic machineries influences the development of metabolic disorders such as diabetes and obesity; then, we focus on discussing the notion that manipulating metabolites, the fuel of cell metabolism, can function as a strategy for interfering epigenetic machinery and its related disease progression as well. PMID:27695375
Architected Cellular Materials
Schaedler, Tobias A.; Carter, William B.
2016-07-01
Additive manufacturing enables fabrication of materials with intricate cellular architecture, whereby progress in 3D printing techniques is increasing the possible configurations of voids and solids ad infinitum. Examples are microlattices with graded porosity and truss structures optimized for specific loading conditions. The cellular architecture determines the mechanical properties and density of these materials and can influence a wide range of other properties, e.g., acoustic, thermal, and biological properties. By combining optimized cellular architectures with high-performance metals and ceramics, several lightweight materials that exhibit strength and stiffness previously unachievable at low densities were recently demonstrated. This review introduces the field of architected materials; summarizes the most common fabrication methods, with an emphasis on additive manufacturing; and discusses recent progress in the development of architected materials. The review also discusses important applications, including lightweight structures, energy absorption, metamaterials, thermal management, and bioscaffolds.
Epigenetics and Cellular Metabolism
Xu, Wenyi; Wang, Fengzhong; Yu, Zhongsheng; Xin, Fengjiao
2016-01-01
Living eukaryotic systems evolve delicate cellular mechanisms for responding to various environmental signals. Among them, epigenetic machinery (DNA methylation, histone modifications, microRNAs, etc.) is the hub in transducing external stimuli into transcriptional response. Emerging evidence reveals the concept that epigenetic signatures are essential for the proper maintenance of cellular metabolism. On the other hand, the metabolite, a main environmental input, can also influence the processing of epigenetic memory. Here, we summarize the recent research progress in the epigenetic regulation of cellular metabolism and discuss how the dysfunction of epigenetic machineries influences the development of metabolic disorders such as diabetes and obesity; then, we focus on discussing the notion that manipulating metabolites, the fuel of cell metabolism, can function as a strategy for interfering epigenetic machinery and its related disease progression as well.
Cellular Response to Irradiation
Institute of Scientific and Technical Information of China (English)
LIU Bo; YAN Shi-Wei
2011-01-01
To explore the nonlinear activities of the cellular signaling system composed of one transcriptional arm and one protein-interaction arm, we use an irradiation-response module to study the dynamics of stochastic interactions.It is shown that the oscillatory behavior could be described in a unified way when the radiation-derived signal and noise are incorporated.
Claman, Henry N.
1973-01-01
Discusses the nature of the immune response and traces many of the discoveries that have led to the present state of knowledge in immunology. The new cellular immunology is directing its efforts toward improving health by proper manipulation of the immune mechanisms of the body. (JR)
Institute of Scientific and Technical Information of China (English)
寇勇刚; 吴桐水; 柳青
2011-01-01
为研究民航运输产业的竞争演化,考虑航空公司的资源竞争力、职能竞争力、核心竞争力及动态核心能力四层次竞争力等因素,建立了元胞自动机模型.以中美两国民航运输产业的竞争演化为例,对主导元胞(航空公司)和支持元胞(机场)的协同发展及其盈利状况进行了模拟研究.研究结果表明,美国民航业放松航空管制后因航空公司动态核心能力不强,行业整体盈利状况不佳；我国民航业半放松管制后,盈利状况也不容乐观.然而,提高航空公司的动态核心能力既可以避免美国民航业发展中经营惨淡的局面,同时又能促进我国民航业的快速发展.%In order to research the competition evolution of the aviation industry, built the cellular automata model with consideration of resource, function, core competence and dynamic core competence of airlines four competition factors. Took competition evolution of the civil aviation industry in China and USA for examples, simulated the coordinated development and profit status of the major cells (airlines) and supportive cells (airports). The result indicates the industry profit status of USA are not good after the deregulation because airlines do not have enough dynamic core competence, the industry profit status of China also are not good after the half-deregulation. However, improving the dynamic core competence of airlines could prevent the civil aviation industry from the loss of USA development example, meanwhile, could promote rapidly development of our country's civil aviation industry, too.
Energy Technology Data Exchange (ETDEWEB)
Rojas C, E. L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Santos C, C. L. [Universidad Autonoma del Estado de Mexico, Paseo Tollocan y Jesus Carranza, Toluca 50120, Estado de Mexico (Mexico)], e-mail: leticia.rojas@inin.gob.mx
2009-10-15
The {sup 188}Re is a radionuclide of radiation gamma emitter, useful in obtaining of gamma-graphic images, but it is also emitter of beta radiations and Auger electrons. A bio-molecule directed to a specific receptor of a cancer cell labeled with a emitter radionuclide of beta particles and Auger electrons, as the {sup 188}Re-Tat-Bombesin, it has the potential to be used in radiotherapy of molecular targets for its capacity to penetrate to cellular nucleus. In this system, the radiation dose is distributed in way located at microscopic levels in sub cellular specific places, where Auger emissions contributes of significant way in absorbed dose. The cellular dosimetry is realized in most of cases, using analytic or semi analytical methods, for example the cellular MIRD methodology. However, it is required to complement these calculations simulating the electrons transport and considering experimental bio kinetics data. Therefore, in this work preliminary results are presented of dosimetric calculation to sub cellular level for {sup 188}Re-Tat-Bombesin by Monte Carlo simulation, using the 2008 version of PENELOPE: PENEASY code. The spatial distribution of absorbed dose in membrane, cytoplasm and nucleus, was calculated with geometry of a cell of 10 {mu}m of diameter, a nucleus of 2 {mu}m of ratio and membrane of 0.2 {mu}m of thickness, considering elementary constitution for each cellular compartment proposal in literature. The total number of disintegrations at sub cellular level was evaluated integrating the activity in function of time starting from experimental bio kinetics data in mamma cancer cells MDA-MB231. The preliminary results show that 46.4% of total disintegrations for unit of captured activity by cell occurs in nucleus, 38.4% in membrane and 15.2% in cytoplasm. The due absorbed dose to Auger electrons for 1 Bq of {sup 188}Re located in cellular membrane were respectively of 1.32E-1 and 1.43E-1 Gy in cytoplasm and nucleus. (Author)
Khan, Muhammad Sadiq Ali; Yousuf, Sidrah
2016-03-01
Cardiac Electrical Activity is commonly distributed into three dimensions of Cardiac Tissue (Myocardium) and evolves with duration of time. The indicator of heart diseases can occur randomly at any time of a day. Heart rate, conduction and each electrical activity during cardiac cycle should be monitor non-invasively for the assessment of "Action Potential" (regular) and "Arrhythmia" (irregular) rhythms. Many heart diseases can easily be examined through Automata model like Cellular Automata concepts. This paper deals with the different states of cardiac rhythms using cellular automata with the comparison of neural network also provides fast and highly effective stimulation for the contraction of cardiac muscles on the Atria in the result of genesis of electrical spark or wave. The specific formulated model named as "States of automaton Proposed Model for CEA (Cardiac Electrical Activity)" by using Cellular Automata Methodology is commonly shows the three states of cardiac tissues conduction phenomena (i) Resting (Relax and Excitable state), (ii) ARP (Excited but Absolutely refractory Phase i.e. Excited but not able to excite neighboring cells) (iii) RRP (Excited but Relatively Refractory Phase i.e. Excited and able to excite neighboring cells). The result indicates most efficient modeling with few burden of computation and it is Action Potential during the pumping of blood in cardiac cycle. PMID:27087101
Molecular and Cellular Signaling
Beckerman, Martin
2005-01-01
A small number of signaling pathways, no more than a dozen or so, form a control layer that is responsible for all signaling in and between cells of the human body. The signaling proteins belonging to the control layer determine what kinds of cells are made during development and how they function during adult life. Malfunctions in the proteins belonging to the control layer are responsible for a host of human diseases ranging from neurological disorders to cancers. Most drugs target components in the control layer, and difficulties in drug design are intimately related to the architecture of the control layer. Molecular and Cellular Signaling provides an introduction to molecular and cellular signaling in biological systems with an emphasis on the underlying physical principles. The text is aimed at upper-level undergraduates, graduate students and individuals in medicine and pharmacology interested in broadening their understanding of how cells regulate and coordinate their core activities and how diseases ...
Alleviate Cellular Congestion Through Opportunistic Trough Filling
Directory of Open Access Journals (Sweden)
Yichuan Wang
2014-04-01
Full Text Available The demand for cellular data service has been skyrocketing since the debut of data-intensive smart phones and touchpads. However, not all data are created equal. Many popular applications on mobile devices, such as email synchronization and social network updates, are delay tolerant. In addition, cellular load varies significantly in both large and small time scales. To alleviate network congestion and improve network performance, we present a set of opportunistic trough filling schemes that leverage the time-variation of network congestion and delay-tolerance of certain traffic in this paper. We consider average delay, deadline, and clearance time as the performance metrics. Simulation results show promising performance improvement over the standard schemes. The work shed lights on addressing the pressing issue of cellular overload.
Overby, Darryl R.; Alenghat, Francis J.; Montoya-Zavala, Martín; Bei, HuCheng; Oh, Philmo; Karavitis, John; Ingber, Donald E.
2004-01-01
This paper focuses on the development of magnetic cellular switches to enable magnetic control of intracellular functions in living mammalian cells, including receptor signal transduction and gene transcription. Our approach takes advantage of the mechanosensitivity of adenosine 3′,5′-monophosphate (cAMP) induction and downstream transcription controlled by the cAMP regulatory element (CRE) to engineer gene constructs that optically report gene expression in living cells. We activate transcri...
Cellular therapy in Tuberculosis
Directory of Open Access Journals (Sweden)
Shreemanta K. Parida
2015-03-01
Full Text Available Cellular therapy now offer promise of potential adjunct therapeutic options for treatment of drug-resistant tuberculosis (TB. We review here the role of Mesenchymal stromal cells, (MSCs, as well as other immune effector cells in the therapy of infectious diseases with a focus on TB. MSCs represent a population of tissue-resident non-hematopoietic adult progenitor cells which home into injured tissues increase the proliferative potential of broncho-alveolar stem cells and restore lung epithelium. MSCs have been shown to be immune-modulatory and anti-inflammatory mediated via cell-cell contacts as well as soluble factors. We discuss the functional profile of MSCs and their potential use for adjunct cellular therapy of multi-drug resistant TB, with the aim of limiting tissue damage, and to convert unproductive inflammatory responses into effective anti-pathogen directed immune responses. Adjunct cellular therapy could potentially offer salvage therapy options for patients with drug-resistant TB, increase clinically relevant anti-M.tuberculosis directed immune responses and possibly shorten the duration of anti-TB therapy.
Environment Aware Cellular Networks
Ghazzai, Hakim
2015-02-01
The unprecedented rise of mobile user demand over the years have led to an enormous growth of the energy consumption of wireless networks as well as the greenhouse gas emissions which are estimated currently to be around 70 million tons per year. This significant growth of energy consumption impels network companies to pay huge bills which represent around half of their operating expenditures. Therefore, many service providers, including mobile operators, are looking for new and modern green solutions to help reduce their expenses as well as the level of their CO2 emissions. Base stations are the most power greedy element in cellular networks: they drain around 80% of the total network energy consumption even during low traffic periods. Thus, there is a growing need to develop more energy-efficient techniques to enhance the green performance of future 4G/5G cellular networks. Due to the problem of traffic load fluctuations in cellular networks during different periods of the day and between different areas (shopping or business districts and residential areas), the base station sleeping strategy has been one of the main popular research topics in green communications. In this presentation, we present several practical green techniques that provide significant gains for mobile operators. Indeed, combined with the base station sleeping strategy, these techniques achieve not only a minimization of the fossil fuel consumption but also an enhancement of mobile operator profits. We start with an optimized cell planning method that considers varying spatial and temporal user densities. We then use the optimal transport theory in order to define the cell boundaries such that the network total transmit power is reduced. Afterwards, we exploit the features of the modern electrical grid, the smart grid, as a new tool of power management for cellular networks and we optimize the energy procurement from multiple energy retailers characterized by different prices and pollutant
Barrio-Parra, Fernando; Rodríguez-Santalla, Inmaculada
2016-08-01
Coastal dunes are sedimentary environments characterized by their high dynamism. Their evolution is determined by sedimentary exchanges between the beach-dune subsystems and the dune dynamics itself. Knowledge about these exchanges is important to prioritize management and conservation strategies of these environments. The aim of this work is the inclusion of the aeolian transport rates obtained using a calibrated cellular automaton to estimate the beach-dune sediment exchange rates in a real active dune field at El Fangar Spit (Ebro Delta, Spain). The dune dynamics model is able to estimate average aeolian sediment fluxes. These are used in combination with the observed net sediment budget to obtain a quantitative characterization of the sediment exchange interactions. The methods produce a substantial improvement in the understanding of coastal sedimentary systems that could have major implications in areas where the management and conservation of dune fields are of concern.
Wang, Weiling; Luo, Sen; Zhu, Miaoyong
2016-03-01
To improve the computational efficiency of the three-dimensional (3D) cellular-automaton-finite-volume-method (CA-FVM) model for describing the dendritic growth of alloy, the block-correction technique (BCT) and the parallel computation approach are introduced. Accordingly, a serial of investigations on the efficiency of the optimized codes in dealing with the designed cases for the melt flow and the heat transfer problems is carried out. Moreover, the accuracy of the present codes is evaluated by the comparisons between the solution to the melt flow and the heat transfer problems and the results from analytical equations and the commercial software. Additionally, the capability of the present CA model is evaluated by comparing the steady growth parameters of the equiaxed dendritic tip and the morphology and the secondary dendrite arm spacing (SDAS) of columnar dendrites with the LGK analytical model and the experimental results of the unidirectional solidification of high-carbon steels. The results show that with the introduction of the 3D BCT, the iteration process of the serial tri-diagonal matrix algorithm (TDMA) code changes from the fluctuation type to the smooth one, and thus, the computational cost is reduced significantly. Moreover, the parallel Jacobi code with one two-dimensional (2D) iteration in 3D BCT is proved to be the most efficient one among the codes compiled in the present work, and therefore, accordingly it is employed to simulate the 3D dendritic growth of alloys. The calculated velocity distribution and temperature variation agree well with the results from the analytical equations and the commercial software. The predicted steady tip velocities agree with the LGK analytical model as the undercooling is 6 K to 7 K. Moreover, the predicted columnar dendritic morphology and SDAS of high-carbon Fe-C alloys during the unidirectional solidification agree with the experimental results.
Mobile Node Localization in Cellular Networks
Directory of Open Access Journals (Sweden)
Yasir Malik
2012-01-01
Full Text Available Location information is the major component in location based applications. This information is used in different safety and service oriented applications to provide users with services according to their Geolocation. There are many approaches to locate mobile nodes in indoor and outdoor environments. In thispaper, we are interested in outdoor localization particularly in cellular networks of mobile nodes andpresented a localization method based on cell and user location information. Our localization method is based on hello message delay (sending and receiving time and coordinate information of Base Transceiver Station (BTSs. To validate our method across cellular network, we implemented and simulated our method in two scenarios i.e. maintaining database of base stations in centralize and distributed system. Simulation results show the effectiveness of our approach and its implementation applicability in telecommunication systems.
Institute of Scientific and Technical Information of China (English)
李锰; 杨峰
2011-01-01
A 2-D cellular automata fault model with 81×81 cells was constructed to test its seismicity performance. In a series of tests 4 kinds of fault strength heterogeneity and 6 different strength geometrical distributions were taken. With the model simulation we analyzed how the fault structure heterogeneity affects macroscopic fault failure behavior and generated seismic sequence type. The results show that with increasing degree of heterogeneity the macroscopic deformation and fracture process present from brittle to plastic behavior, and produce 3 different types of seismic sequence, I.e. , main shock type, foreshock-main shock-aftershock type and swarm type. In the same time, with increasing fault strength heterogeneity the fracture size distribution more regularly follows the G-R relation. Besides, temporarily the events occur in a certain random process, that is, small events appear randomly, medium size events occur in clusters and large ones emerge quasi-periodically. The event clustering and quasi-periodic occurrences become less significant with the fault heterogeneity increasing. It is also found that the randomness of structural geometric variation may affect characteristics of seismic sequences, but the difference in randomness becomes weaker as degree of heterogeneity increases.%基于断层强度分布的非均匀性,构建了由81×81个细胞单元组成的4种不同匀质度及其各自6种不同随机构型共计24个非均匀二维单断层模型样本,并通过设计的细胞自动机模拟程序,在保持其它模拟参数不变的条件下对它们进行了模拟试验.研究结果表明,随着断层结构非匀质度的增加,其宏观变形破坏行为由相对脆性向塑性变化；地震序列类型依次表现出主震型、前震-主震-余震型和震群型；震级分布表现出非均匀性依次减小；地震发生在时间上表现为一种确定性的随机过程,即小震随机、中强地震丛集和大震准周期的特点.此
Engineering Cellular Metabolism
DEFF Research Database (Denmark)
Nielsen, Jens; Keasling, Jay
2016-01-01
of metabolic engineering and will discuss how new technologies can enable metabolic engineering to be scaled up to the industrial level, either by cutting off the lines of control for endogenous metabolism or by infiltrating the system with disruptive, heterologous pathways that overcome cellular regulation.......Metabolic engineering is the science of rewiring the metabolism of cells to enhance production of native metabolites or to endow cells with the ability to produce new products. The potential applications of such efforts are wide ranging, including the generation of fuels, chemicals, foods, feeds...
Institute of Scientific and Technical Information of China (English)
王冬; 苗宗成; 王向轲; 曹晖
2013-01-01
The polymer crystallization process and mechanism were studied by computer simulation method. It is benefit to understand the crystallization kinetics by comparing the simulated results with the experimental results. Based on a nonconserved spatiotemporal Ginzburg-Landau equation TDGL model, a novel three dimensional phase field model was established by combining the cellular automaton method with the general phase field model. For simulating the real three dimensional polymer crystallization process, the cellular automaton method was modified by the different steric structures and discretization methods. The different steric structures or discretization methods are related to the lattice parameters of syndiotactic polypropylene single crystals and the crystal growth faces of polymer single crystals. It was suggested that the novel method is a way of building bridges between the diffusion equation and polymer characterization. Moreover, the diffusion equations are discretized according to the diffusion coefficient of every lattice site in various crystal growth faces,and the shape of lattice is selected based on the real proportion of the unit cell dimensions. Especially, the other physics parameters of syndiotactic polypropylene also were introduced into the phase field model. The spatio-temporal growth of syndiotactic polypropylene single crystals during isothermal crystallization was simulated by the novel three dimensional phase field model. Three dimensional numerical calculations are performed to elucidate the faceted single crystal growth including square, rectangular, lozenge-shaped, and hexagonal single crystals. The corresponding three dimensional results were illustrated by the MatLab. Our simulated patterns are in good agreement with the experimental morphologies, and the physical origin of polymer single crystal growth is discussed.%利用元胞自动机方法与相场模型的结合建立新型三维模拟相场模型.同时,为模拟真实的、三
Synchronization, TIGoRS, and Information Flow in Complex Systems: Dispositional Cellular Automata.
Sulis, William H
2016-04-01
Synchronization has a long history in physics where it refers to the phase matching of two identical oscillators. This notion has been extensively studied in physics as well as in biology, where it has been applied to such widely varying phenomena as the flashing of fireflies and firing of neurons in the brain. Human behavior, however, may be recurrent but it is not oscillatory even though many physiological systems do exhibit oscillatory tendencies. Moreover, much of human behaviour is collaborative and cooperative, where the individual behaviours may be distinct yet contemporaneous (if not simultaneous) and taken collectively express some functionality. In the context of behaviour, the important aspect is the repeated co-occurrence in time of behaviours that facilitate the propagation of information or of functionality, regardless of whether or not these behaviours are similar or identical. An example of this weaker notion of synchronization is transient induced global response synchronization (TIGoRS). Previous work has shown that TIGoRS is a ubiquitous phenomenon among complex systems, enabling them to stably parse environmental transients into salient units to which they stably respond. This leads to the notion of Sulis machines, which emergently generate a primitive linguistic structure through their dynamics. This article reviews the notion of TIGoRS and its expression in several complex systems models including tempered neural networks, driven cellular automata and cocktail party automata. The emergent linguistics of Sulis machines are discussed. A new class of complex systems model, the dispositional cellular automaton is introduced. A new metric for TIGoRS, the excess synchronization, is introduced and applied to the study of TIGoRS in dispositional cellular automata. It is shown that these automata exhibit a nonlinear synchronization response to certain perturbing transients.
Synchronization, TIGoRS, and Information Flow in Complex Systems: Dispositional Cellular Automata.
Sulis, William H
2016-04-01
Synchronization has a long history in physics where it refers to the phase matching of two identical oscillators. This notion has been extensively studied in physics as well as in biology, where it has been applied to such widely varying phenomena as the flashing of fireflies and firing of neurons in the brain. Human behavior, however, may be recurrent but it is not oscillatory even though many physiological systems do exhibit oscillatory tendencies. Moreover, much of human behaviour is collaborative and cooperative, where the individual behaviours may be distinct yet contemporaneous (if not simultaneous) and taken collectively express some functionality. In the context of behaviour, the important aspect is the repeated co-occurrence in time of behaviours that facilitate the propagation of information or of functionality, regardless of whether or not these behaviours are similar or identical. An example of this weaker notion of synchronization is transient induced global response synchronization (TIGoRS). Previous work has shown that TIGoRS is a ubiquitous phenomenon among complex systems, enabling them to stably parse environmental transients into salient units to which they stably respond. This leads to the notion of Sulis machines, which emergently generate a primitive linguistic structure through their dynamics. This article reviews the notion of TIGoRS and its expression in several complex systems models including tempered neural networks, driven cellular automata and cocktail party automata. The emergent linguistics of Sulis machines are discussed. A new class of complex systems model, the dispositional cellular automaton is introduced. A new metric for TIGoRS, the excess synchronization, is introduced and applied to the study of TIGoRS in dispositional cellular automata. It is shown that these automata exhibit a nonlinear synchronization response to certain perturbing transients. PMID:27033136
Harper, Jason C.
The generation of new three-dimensional (3D) matrices that enable integration of biomolecular components and whole cells into device architectures, without adversely altering their morphology or activity, continues to be an expanding and challenging field of research. This research is driven by the promise that encapsulated biomolecules and cells can significantly impact areas as diverse as biocatalysis, controlled delivery of therapeutics, environmental and industrial process monitoring, early warning of warfare agents, bioelectronics, photonics, smart prosthetics, advanced physiological sensors, portable medical diagnostic devices, and tissue/organ replacement. This work focuses on the development of a fundamental understanding of the biochemical and nanomaterial mechanisms that govern the cell directed assembly and integration process. It was shown that this integration process relies on the ability of cells to actively develop a pH gradient in response to evaporation induced osmotic stress, which catalyzes silica condensation within a thin 3D volume surrounding the cells, creating a functional bio/nano interface. The mechanism responsible for introducing functional foreign membrane-bound proteins via proteoliposome addition to the silica-lipid-cell matrix was also determined. Utilizing this new understanding, 3D cellular immobilization capabilities were extended using sol-gel matrices endowed with glycerol, trehalose, and media components. The effects of these additives, and the metabolic phase of encapsulated S. cerivisiase cells, on long-term viability and the rate of inducible gene expression was studied. This enabled the entrapment of cells within a novel microfluidic platform capable of simultaneous colorimetric, fluorescent, and electrochemical detection of a single analyte, significantly improving confidence in the biosensor output. As a complementary approach, multiphoton protein lithography was utilized to engineer 3D protein matrices in which to
Bao, Yi; Chen, Ming
2011-01-01
Modern radio communication is faced with a problem about how to distribute restricted frequency to users in a certain space. Since our task is to minimize the number of repeaters, a natural idea is enlarging coverage area. However, coverage has restrictions. First, service area has to be divided economically as repeater's coverage is limited. In this paper, our fundamental method is to adopt seamless cellular network division. Second, underlying physics content in frequency distribution problem is interference between two close frequencies. Consequently, we choose a proper frequency width of 0.1MHz and a relevantly reliable setting to apply one frequency several times. We make a few general assumptions to simplify real situation. For instance, immobile users yield to homogenous distribution; repeaters can receive and transmit information in any given frequency in duplex operation; coverage is mainly decided by antenna height. Two models are built up to solve 1000 users and 10000 users situations respectively....
Institute of Scientific and Technical Information of China (English)
卢鹏; 岳彩荣; 冯水琴; 任健; 岑纲; 禄鑫
2011-01-01
选取林地面积减少较为严重的滇西北香格里拉县为例,对研究区的土地利用变化驱动机制进行了分析,并集合GIS技术,尝试运用元胞自动机理论构建Loit模型对研究区的土地利用空间格局进行了模拟和预测.模拟的Kappa指数为0.79,表明CA模型在土地利用/覆盖变化的预测方面有巨大优势.%A study was conducted to analyze the land-use change-driven mechanism of forest land in Shangri-La County, northwest Yunnan Province, where the forest land area decreased more seriously. The spatial pattern of land use in the study area was simulated and predicted by CIS technology and the Logit Model obtained from the cellular automata theory. The kappa index of the simulation was 0. 79, indicating that the cellular automata model has more advantages in the simulation of Land use/cover change.
Cyber Physical Systems: A New Approach to Power Electronics Simulation, Control and Testing
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CELANOVIC, N. L.
2012-02-01
Full Text Available This paper presents a Cyber Physical Systems approach to power electronics simulation, control and testing. We present a new framework based on generalized hybrid automaton and application specific ultra-low latency high-speed processor architecture that enables high fidelity real-time power electronics model computation. To illustrate the performance of this approach we experimentally demonstrate two extremely computationally demanding power electronics applications: real-time emulation for Hardware-in-the-Loop (HIL testing, and hybrid system observers for fault detection and isolation.
Never-ageing cellular senescence
Ogrunc, Müge; d’Adda di Fagagna, Fabrizio
2011-01-01
Cellular senescence was historically discovered as a form of cellular ageing of in vitro cultured cells. It has been under the spotlight following the evidence of oncogene-induced senescence in vivo and its role as a potent tumour suppressor mechanism. Presently, a PubMed search using keywords ‘cellular senescence and cancer’ reveals 8398 number of references (by April 2011) showing that while our knowledge of senescence keeps expanding, the complexity of the phenomenon keeps us – researchers...
Yim, Youngbin
2003-01-01
Cellular probe technology is one of several potentially promising technologies for obtaining accurate travel time information. In 1996, the Federal Communications Commission (FCC) mandated E911 requirements that cellular location be provided when 911 emergency calls come in to emergency management authorities. The E911 requirements allow 50 -300 meters from the emergency call location, depending on the type of cellular phone technology used and whether handset-based or network-based solutions...
Realistic Simulation of Rice Plant
Institute of Scientific and Technical Information of China (English)
DING Wei-long; ZHANG Yu-ping; ZHANG Qian-yuan; ZHU De-feng; CHEN Qi
2011-01-01
The existing research results of virtual modeling of rice plant,however,is far from perfect compared to that of other crops due to its complex structure and growth process.Techniques to visually simulate the architecture of rice plant and its growth process are presented based on the analysis of the morphological characteristics at different stages.Firstly,the simulations of geometrical shape,the bending status and the structural distortion of rice leaves are conducted.Then,by using an improved model for bending deformation,the curved patterns of panicle axis and various types of panicle branches are generated,and the spatial shape of rice panicle is therefore created.Parametric L-system is employed to generate its topological structures,and finite-state automaton is adopted to describe the development of geometrical structures.Finally,the computer visualization of three-dimensional morphologies of rice plant at both organ and individual levels is achieved.The experimental results showed that the proposed methods of modeling the three-dimensional shapes of organs and simulating the growth of rice plant are feasible and effective,and the generated three-dimensional images are realistic.
Cellular bioluminescence imaging.
Welsh, David K; Noguchi, Takako
2012-08-01
Bioluminescence imaging of live cells has recently been recognized as an important alternative to fluorescence imaging. Fluorescent probes are much brighter than bioluminescent probes (luciferase enzymes) and, therefore, provide much better spatial and temporal resolution and much better contrast for delineating cell structure. However, with bioluminescence imaging there is virtually no background or toxicity. As a result, bioluminescence can be superior to fluorescence for detecting and quantifying molecules and their interactions in living cells, particularly in long-term studies. Structurally diverse luciferases from beetle and marine species have been used for a wide variety of applications, including tracking cells in vivo, detecting protein-protein interactions, measuring levels of calcium and other signaling molecules, detecting protease activity, and reporting circadian clock gene expression. Such applications can be optimized by the use of brighter and variously colored luciferases, brighter microscope optics, and ultrasensitive, low-noise cameras. This article presents a review of how bioluminescence differs from fluorescence, its applications to cellular imaging, and available probes, optics, and detectors. It also gives practical suggestions for optimal bioluminescence imaging of single cells.
Knowledge discovery for geographical cellular automata
Institute of Scientific and Technical Information of China (English)
LI Xia; Anthony Gar-On Yeh
2005-01-01
This paper proposes a new method for geographical simulation by applying data mining techniques to cellular automata. CA has strong capabilities in simulating complex systems. The core of CA is how to define transition rules. There are no good methods for defining these transition rules. They are usually defined by using heuristic methods and thus subject to uncertainties. Mathematical equations are used to represent transition rules implicitly and have limitations in capturing complex relationships. This paper demonstrates that the explicit transition rules of CA can be automatically reconstructed through the rule induction procedure of data mining. The proposed method can reduce the influences of individual knowledge and preferences in defining transition rules and generate more reliable simulation results. It can efficiently discover knowledge from a vast volume of spatial data.
Modeling cellular deformations using the level set formalism
Yang Liu; Effler Janet C; Kutscher Brett L; Sullivan Sarah E; Robinson Douglas N; Iglesias Pablo A
2008-01-01
Abstract Background Many cellular processes involve substantial shape changes. Traditional simulations of these cell shape changes require that grids and boundaries be moved as the cell's shape evolves. Here we demonstrate that accurate cell shape changes can be recreated using level set methods (LSM), in which the cellular shape is defined implicitly, thereby eschewing the need for updating boundaries. Results We obtain a viscoelastic model of Dictyostelium cells using micropipette aspiratio...
Interference cancellation technique under imperfect synchronization in cellular systems
Institute of Scientific and Technical Information of China (English)
WANG; Xin; WU; Zhuo
2009-01-01
In this paper, an asynchronous cooperative cellular system applied with space-time block coding(STBC)is investigated. A signal detector is proposed based on parallel interference cancellation(PIC), to cancel the inter-symbol interference(ISI)caused by the imperfect synchronization. Simulation results show that the proposed PIC detector can effectively suppress the ISI, but there is still a comparatively high error floor, due to the co-channel interference(CCI)of the cellular system.
Optimizing Cellular Networks Enabled with Renewal Energy via Strategic Learning.
Directory of Open Access Journals (Sweden)
Insoo Sohn
Full Text Available An important issue in the cellular industry is the rising energy cost and carbon footprint due to the rapid expansion of the cellular infrastructure. Greening cellular networks has thus attracted attention. Among the promising green cellular network techniques, the renewable energy-powered cellular network has drawn increasing attention as a critical element towards reducing carbon emissions due to massive energy consumption in the base stations deployed in cellular networks. Game theory is a branch of mathematics that is used to evaluate and optimize systems with multiple players with conflicting objectives and has been successfully used to solve various problems in cellular networks. In this paper, we model the green energy utilization and power consumption optimization problem of a green cellular network as a pilot power selection strategic game and propose a novel distributed algorithm based on a strategic learning method. The simulation results indicate that the proposed algorithm achieves correlated equilibrium of the pilot power selection game, resulting in optimum green energy utilization and power consumption reduction.
Optimizing Cellular Networks Enabled with Renewal Energy via Strategic Learning.
Sohn, Insoo; Liu, Huaping; Ansari, Nirwan
2015-01-01
An important issue in the cellular industry is the rising energy cost and carbon footprint due to the rapid expansion of the cellular infrastructure. Greening cellular networks has thus attracted attention. Among the promising green cellular network techniques, the renewable energy-powered cellular network has drawn increasing attention as a critical element towards reducing carbon emissions due to massive energy consumption in the base stations deployed in cellular networks. Game theory is a branch of mathematics that is used to evaluate and optimize systems with multiple players with conflicting objectives and has been successfully used to solve various problems in cellular networks. In this paper, we model the green energy utilization and power consumption optimization problem of a green cellular network as a pilot power selection strategic game and propose a novel distributed algorithm based on a strategic learning method. The simulation results indicate that the proposed algorithm achieves correlated equilibrium of the pilot power selection game, resulting in optimum green energy utilization and power consumption reduction. PMID:26167934
基于土壤侵蚀的元胞自动机转换规则框架%The Transition Rule Frame for Cellular Automata based on Soil Erosion
Institute of Scientific and Technical Information of China (English)
赵京
2014-01-01
The erosion process of the Loess Plateau can be regarded as the computation of a huge comles system, cellular automaton is a theoretical model which couldreact the comlexphenomenonverywel due to the charataristc of itsnonlinearness than the other traditional model in the are a of soilerosion forecast.Inthispaper,we use the theory of cel ularautomata to disscuss the process of soilerosionon the micro-scale,we for cuson the dynamicbalance of water and soil in each cel to built a transition rule frame of erosion cel ular automata, single flow direction algorithm cal ed D8(Deterministic eight-node) appoint the outflow direction and use the multi-agent proguammable modeling environment cal ed NelLogo to simulate the transition rule, the com-putaionofthecel ularautomatonshowsgoodresult.%黄土高原的土壤侵蚀过程可以被看做是一种地形演变的复杂系统。元胞自动机是一种能够很好的体现这样复杂现象的理论模型，因其非线性的特点使得其在土壤侵蚀的预测方面相比其他模型能够有一定的优势。本文利用元胞自动机的思想对于在降雨条件下的土壤侵蚀过程进行探究。利用每个单位元胞内的水量平衡和泥沙平衡构建元胞之间各参数的转换规则，利用D8流向算法计算水流方向。综合得出一种基于水量平衡与泥沙平衡的土壤侵蚀元胞自动机转换规则框架，并利用netlogo建模环境来实现模型，得出了较好的模拟结果。
An efficient Cellular Potts Model algorithm that forbids cell fragmentation
Durand, Marc; Guesnet, Etienne
2016-11-01
The Cellular Potts Model (CPM) is a lattice based modeling technique which is widely used for simulating cellular patterns such as foams or biological tissues. Despite its realism and generality, the standard Monte Carlo algorithm used in the scientific literature to evolve this model preserves connectivity of cells on a limited range of simulation temperature only. We present a new algorithm in which cell fragmentation is forbidden for all simulation temperatures. This allows to significantly enhance realism of the simulated patterns. It also increases the computational efficiency compared with the standard CPM algorithm even at same simulation temperature, thanks to the time spared in not doing unrealistic moves. Moreover, our algorithm restores the detailed balance equation, ensuring that the long-term stage is independent of the chosen acceptance rate and chosen path in the temperature space.
Station Model for Rail Transit System Using Cellular Automata
Institute of Scientific and Technical Information of China (English)
XUN Jing; NING Bin; LI Ke-Ping
2009-01-01
In this paper, we propose a new cellular automata model to simulate the railway traffic at station.Based on NaSch model, the proposed station model is composed of the main track and the siding track.Two different schemes for trains passing through station are considered.One is the scheme of "pass by the main track, start and stop by the siding track".The other is the scheme of "two tracks play the same role".We simulate the train movement using the proposed model and analyze the traffic flow at station.The simulation results demonstrate that the proposed cellular automata model can be successfully used for the simulations of railway traffic.Some characteristic behaviors of railway traffic flow can be reproduced.Moreover, the simulation values of the minimum headway are close to the theoretical values.This result demonstrates the dependability and availability of the proposed model.
ProtNet: a tool for stochastic simulations of protein interaction networks dynamics
Bernaschi, Massimo; Castiglione, Filippo; Ferranti, Alessandra; Gavrila, Caius; Tinti, Michele; Cesareni, Gianni
2007-01-01
we have compared the dynamics of complex formation in a two and a three dimensional lattice model. Conclusion ProtNet is a cellular automaton model, where each protein molecule or complex is explicitly represented and where simple interaction rules are applied to populations of discrete particles. This tool can be used to simulate the dynamics of protein interactions in the cell. PMID:17430571
Single spin measurement using cellular automata techniques
Perez-Delgado, C A; Cory, D G; Mosca, M; Cappellaro, Paola; Cory, David G.; Mosca, Michele; Perez-Delgado, Carlos A.
2006-01-01
We propose an approach for single spin measurement. Our method uses techniques from the theory of quantum cellular automata to correlate a large amount of ancillary spins to the one to be measured. It has the distinct advantage of being efficient, and to a certain extent fault-tolerant. Under ideal conditions, it requires the application of only order of cube root of N steps (each requiring a constant number of rf pulses) to create a system of N correlated spins. It is also fairly robust against pulse errors, imperfect initial polarization of the ancilla spin system, and does not rely on entanglement. We study the scalability of our scheme through numerical simulation.
Institute of Scientific and Technical Information of China (English)
秦大康; 江志松
2008-01-01
使用禁止字理论、计算机搜索和符号动力学的方法对7号初等元胞自动机生成的时间序列从形式语言的角度进行复杂性分析,确定了禁止字集及其Chomsky层次,确定了演化语言的一个精简的Chomsky层次,并由此得到了时间序列的完整描述.
基于一维人工细胞自动机的肿瘤生长模型研究%A TUMOR GROWTH MODEL DESIGNED WITH A ONE DIMENSIONAL CELLULAR AUTOMATON
Institute of Scientific and Technical Information of China (English)
阮晓刚; 胡日查
2003-01-01
通过对Gompertz肿瘤生长理论模型的研究和分析,设计了一种基于一维人工细胞自动机的肿瘤生长模型(TGM1dCA).在连续Gompertz模型基础上,论文导出了Gompertz模型的离散差分形式.运用离散Gompertz模型,论文设计出了体现肿瘤生长动态的人工细胞自动机状态随机演化规则.论文对TGM1dCA细胞自动机进行了理论分析和仿真实验,理论分析和仿真实验结果表明,TGM1dCA细胞自动机与Gompertz模型和临床实验数据具有良好的一致性.
Individual-based lattice model for spatial spread of epidemics
Directory of Open Access Journals (Sweden)
Henryk Fuks
2001-01-01
Full Text Available We present a lattice gas cellular automaton (LGCA to study spatial and temporal dynamics of an epidemic of SIR (susceptible-infected-removed type. The automaton is fully discrete, i.e., space, time and number of individuals are discrete variables. The automaton can be applied to study spread of epidemics in both human and animal populations. We investigate effects of spatial inhomogeneities in initial distribution of infected and vaccinated populations on the dynamics of epidemic of SIR type. We discuss vaccination strategies which differ only in spatial distribution of vaccinated individuals. Also, we derive an approximate, mean-field type description of the automaton, and discuss differences between the mean-field dynamics and the results ofLGCA simulation.
Cellular systems biology profiling applied to cellular models of disease.
Giuliano, Kenneth A; Premkumar, Daniel R; Strock, Christopher J; Johnston, Patricia; Taylor, Lansing
2009-11-01
Building cellular models of disease based on the approach of Cellular Systems Biology (CSB) has the potential to improve the process of creating drugs as part of the continuum from early drug discovery through drug development and clinical trials and diagnostics. This paper focuses on the application of CSB to early drug discovery. We discuss the integration of protein-protein interaction biosensors with other multiplexed, functional biomarkers as an example in using CSB to optimize the identification of quality lead series compounds.
Institute of Scientific and Technical Information of China (English)
H. Demirel; A. (O)zkan; B. Kutlu
2008-01-01
The Blume-Capel model in the presence of external magnetic field H has been simulated using a cellular automaton algorithm improved from the Creutz cellular automaton in three-dimension lattice. The field critical exponent δ is estimated using the power law relations and the finite size scaling functions for the magnetization and the susceptibility in the range -0.1≤h=H/J≤0. The estimated value of the field critical exponent δ is in good agreement with the universal value (δ=5) in three dimensions. The simulations are carried out on a simple cubic lattice under periodic boundary conditions.
Dynamic Channel Allocation in Sectored Cellular Systems
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
It is known that dynamic channel assignment(DCA) strategy outperforms the fixed channel assignment(FCA) strategy in omni-directional antenna cellular systems. One of the most important methods used in DCA was channel borrowing. But with the emergence of cell sectorization and spatial division multiple access(SDMA) which are used to increase the capacity of cellular systems, the channel assignment faces a series of new problems. In this paper, a dynamic channel allocation scheme based on sectored cellular systems is proposed. By introducing intra-cell channel borrowing (borrowing channels from neighboring sectors) and inter-cell channel borrowing (borrowing channels from neighboring cells) methods, previous DCA strategies, including compact pattern based channel borrowing(CPCB) and greedy based dynamic channel assignment(GDCA) schemes proposed by the author, are improved significantly. The computer simulation shows that either intra-cell borrowing scheme or inter-cell borrowing scheme is efficient enough to uniform and non-uniform traffic service distributions.
Actual problems of cellular cardiomyoplasty
Directory of Open Access Journals (Sweden)
Bulat Kaupov
2010-04-01
Full Text Available The paper provides review of cellular technologies used incardiology, describes types of cellular preparations depending onsources of cells and types of compounding cells. The generalmechanisms of therapies with stem cells applications are described.Use of cellular preparations for treatment of cardiovascular diseasesand is improvement of the forecast at patients with heartinsufficiency of various genesis is considered as alternative topractice with organ transplantations. Efforts of biotechnologicallaboratories are directed on search of optimum population of cellsfor application in cardiology and studying of mechanisms andfactors regulating function of cardiac stem cells.
Combinatorial approaches to evaluate nanodiamond uptake and induced cellular fate
Eldawud, Reem; Reitzig, Manuela; Opitz, Jörg; Rojansakul, Yon; Jiang, Wenjuan; Nangia, Shikha; Zoica Dinu, Cerasela
2016-02-01
Nanodiamonds (NDs) are an emerging class of engineered nanomaterials that hold great promise for the next generation of bionanotechnological products to be used for drug and gene delivery, or for bio-imaging and biosensing. Previous studies have shown that upon their cellular uptake, NDs exhibit high biocompatibility in various in vitro and in vivo set-ups. Herein we hypothesized that the increased NDs biocompatibility is a result of minimum membrane perturbations and their reduced ability to induce disruption or damage during cellular translocation. Using multi-scale combinatorial approaches that simulate ND-membrane interactions, we correlated NDs real-time cellular uptake and kinetics with the ND-induced membrane fluctuations to derive energy requirements for the uptake to occur. Our discrete and real-time analyses showed that the majority of NDs internalization occurs within 2 h of cellular exposure, however, with no effects on cellular viability, proliferation or cellular behavior. Furthermore, our simulation analyses using coarse-grained models identified key changes in the energy profile, membrane deformation and recovery time, all functions of the average ND or ND-based agglomerate size. Understanding the mechanisms responsible for ND-cell membrane interactions could possibly advance their implementation in various biomedical applications.
Cellular mechanisms during vascular development
Blum, Yannick
2012-01-01
The vascular system is an essential organ in vertebrate animals and provides the organism with enough oxygen and nutrients. It is composed of an interconnected network of blood vessels, which form using a number of different morphogenetic mechanisms. Angiogenesis describes the formation of new blood vessels from preexisting vessels. A number of molecular pathways have been shown to be essential during angiogenesis. However, cellular architecture of blood vessels as well as cellular mechanisms...
Mathematical Modeling of Cellular Metabolism.
Berndt, Nikolaus; Holzhütter, Hermann-Georg
2016-01-01
Cellular metabolism basically consists of the conversion of chemical compounds taken up from the extracellular environment into energy (conserved in energy-rich bonds of organic phosphates) and a wide array of organic molecules serving as catalysts (enzymes), information carriers (nucleic acids), and building blocks for cellular structures such as membranes or ribosomes. Metabolic modeling aims at the construction of mathematical representations of the cellular metabolism that can be used to calculate the concentration of cellular molecules and the rates of their mutual chemical interconversion in response to varying external conditions as, for example, hormonal stimuli or supply of essential nutrients. Based on such calculations, it is possible to quantify complex cellular functions as cellular growth, detoxification of drugs and xenobiotic compounds or synthesis of exported molecules. Depending on the specific questions to metabolism addressed, the methodological expertise of the researcher, and available experimental information, different conceptual frameworks have been established, allowing the usage of computational methods to condense experimental information from various layers of organization into (self-) consistent models. Here, we briefly outline the main conceptual frameworks that are currently exploited in metabolism research.
Membrane potential mediates the cellular binding of nanoparticles
Shin, Edwin H.; Li, Ye; Kumar, Umesh; Sureka, Hursh V.; Zhang, Xianren; Payne, Christine K.
2013-06-01
The use of nanoparticles for cellular therapeutic or sensing applications requires nanoparticles to bind, or adhere, to the cell surface. While nanoparticle parameters such as size, shape, charge, and composition are important factors in cellular binding, the cell itself must also be considered. All cells have an electrical potential across the plasma membrane driven by an ion gradient. Under standard conditions the ion gradient will result in a -10 to -100 mV potential across the membrane with a net negative charge on the cytosolic face. Using a combination of flow cytometry and fluorescence microscopy experiments and dissipative particle dynamics simulations, we have found that a decrease in membrane potential leads to decreased cellular binding of anionic nanoparticles. The decreased cellular binding of anionic nanoparticles is a general phenomenon, independent of depolarization method, nanoparticle composition, and cell type. Increased membrane potential reverses this trend resulting in increased binding of anionic nanoparticles. The cellular binding of cationic nanoparticles is minimally affected by membrane potential due to the interaction of cationic nanoparticles with cell surface proteins. The influence of membrane potential on the cellular binding of nanoparticles is especially important when considering the use of nanoparticles in the treatment or detection of diseases, such as cancer, in which the membrane potential is decreased.The use of nanoparticles for cellular therapeutic or sensing applications requires nanoparticles to bind, or adhere, to the cell surface. While nanoparticle parameters such as size, shape, charge, and composition are important factors in cellular binding, the cell itself must also be considered. All cells have an electrical potential across the plasma membrane driven by an ion gradient. Under standard conditions the ion gradient will result in a -10 to -100 mV potential across the membrane with a net negative charge on the
Hierarchical Cellular Structures in High-Capacity Cellular Communication Systems
Jain, R K; Agrawal, N K
2011-01-01
In the prevailing cellular environment, it is important to provide the resources for the fluctuating traffic demand exactly in the place and at the time where and when they are needed. In this paper, we explored the ability of hierarchical cellular structures with inter layer reuse to increase the capacity of mobile communication network by applying total frequency hopping (T-FH) and adaptive frequency allocation (AFA) as a strategy to reuse the macro and micro cell resources without frequency planning in indoor pico cells [11]. The practical aspects for designing macro- micro cellular overlays in the existing big urban areas are also explained [4]. Femto cells are inducted in macro / micro / pico cells hierarchical structure to achieve the required QoS cost effectively.
Institute of Scientific and Technical Information of China (English)
李锰; 杨峰
2011-01-01
For the purpose of investigating conditions of earthquake pregnancy,a heterogeneous 2-D single fault model with 81×81 cells is set up. By using cellular automata models and changing the model heterogeneity and correlation parameters respectively,we compute and get different synthetic event catalogues for analyzing general seismic activity and intensity distribution properties. The computation results show that different heterogeneous structures produce different seismic sequence types and G-R relation,so the heterogeneity is an important influencing factor on seismicity. Nevertheless ,both the coefficients of stress redistribution and local friction loss can also influence seimicity to some extent. It is possibly helpful for further understandings of earthquake process complexity.%基于细胞自动机模型,构建了由81×81个细胞单元组成非均匀二维单断层介质样本,研究了断层结构细观非均匀性以及相关模型参数变化对模拟输出结果和强度分布特征的影响.研究结果表明:结构非均匀性是影响地震活动性的控制性参量,随着非均匀程度的增强,地震事件数量增多,震级分布变得越来越均匀,破裂演化模式由相对“脆性”向“塑性”变化；介质结构的初始条件和应力加载的随机性对地震活动演化过程基本不产生影响,此外,应力降分配系数减小使b值主体线性段向大震级延伸；随着局部摩擦损耗系数增大,模拟地震事件的数量有所增加,大震级事件数量和震级衰减增强,b值主体线性区间变窄,使断层的变形破坏方式由相对“脆性”向“塑性”变化.这些对理解孕震过程的复杂性是有帮助的.
Half-Cell Law of Regular Cellular Detonations
Institute of Scientific and Technical Information of China (English)
WANG Chun; JIANG Zong-Lin; GAO Yun-Liang
2008-01-01
Numerical simulations illustrate the half-cell law of regular cellular detonations propagating in confined space,i.e., the number of cells always maintains an integral multiple of half cell. The cells adapt themselves larger or smaller to the size of the unconfined space by maintaining the cell scale larger or smaller than the original cells of detonation.
Cellular automata modeling of cooperative eutectic growth
Directory of Open Access Journals (Sweden)
E. Olejnik
2010-01-01
Full Text Available The model and results of the 2D simulation of the cooperative growth of two phases in the lamellar eutectic are presented. The pro-posed model takes into account heat transfer, components diffusion and nonstationary concentration distribution in the liquid and solid phases, non-equlibrium nature of the phase transformation and kinetics of the growth, influence of the surface energy and interface curva-ture on the conditions of the thermodynamic equilibrium. For the determination of the phase interface shape the Cellular Automata tech-nique (CA was used. For the calculation of temperature and concentration distribution the numerical solution of the Fourier equation was used. The partial differential equations were solved by Finite Differences Method (FDM. The spatial position and cell sizes of CA lattice and FDM mesh are equal.Proposed model can predict the steady state growth with a constant interlamellar spacing in the regular plate eutectic, as well as some transient processes that bring to the changes of that parameters. Obtained simulation data show the solid-liquid interface changes result in the termination of lamella and enlargement of interlamellar spacing. Another simulation results illustrate a pocket formation in the center of one phase that forestalls nucleation (or intergrowth of the new lamellae of another phase. The data of the solidification study of the transparent material (CBr4 – 8,4% C2Cl6 obtained in the thin layer demonstrate the qualita-tive agreement of the simulation.
Parallelizing the Cellular Potts Model on graphics processing units
Tapia, José Juan; D'Souza, Roshan M.
2011-04-01
The Cellular Potts Model (CPM) is a lattice based modeling technique used for simulating cellular structures in computational biology. The computational complexity of the model means that current serial implementations restrict the size of simulation to a level well below biological relevance. Parallelization on computing clusters enables scaling the size of the simulation but marginally addresses computational speed due to the limited memory bandwidth between nodes. In this paper we present new data-parallel algorithms and data structures for simulating the Cellular Potts Model on graphics processing units. Our implementations handle most terms in the Hamiltonian, including cell-cell adhesion constraint, cell volume constraint, cell surface area constraint, and cell haptotaxis. We use fine level checkerboards with lock mechanisms using atomic operations to enable consistent updates while maintaining a high level of parallelism. A new data-parallel memory allocation algorithm has been developed to handle cell division. Tests show that our implementation enables simulations of >10 cells with lattice sizes of up to 256 3 on a single graphics card. Benchmarks show that our implementation runs ˜80× faster than serial implementations, and ˜5× faster than previous parallel implementations on computing clusters consisting of 25 nodes. The wide availability and economy of graphics cards mean that our techniques will enable simulation of realistically sized models at a fraction of the time and cost of previous implementations and are expected to greatly broaden the scope of CPM applications.
Continuum representations of cellular solids
Energy Technology Data Exchange (ETDEWEB)
Neilsen, M.K.
1993-09-01
Cellular materials consist of interconnected struts or plates which form cells. The struts or plates are constructed from a variety of metals, polymers, ceramics and wood products. Cellular materials are often used in impact limiters for shipping containers to protect the contents from accidental impact events. These materials exhibit a variety of complex behavior when subjected to crushing loads. This research focuses on the development of continuum representations of cellular solids that can be used in the finite element analysis of shipping container accidents. A significant portion of this work is the development of a new methodology to relate localized deformations to appropriate constitutive descriptions. This methodology provides the insight needed to select constitutive descriptions for cellular solids that capture the localized deformations that are observed experimentally. Constitutive relations are developed for two different cellular materials, aluminum honeycomb and polyurethane foam. These constitutive relations are based on plasticity and continuum damage theories. Plasticity is used to describe the permanent deformation exhibited by both aluminum honeycomb and polyurethane foam. Continuum damage is needed to capture the change in elastic parameters due to cracking of the polyurethane cell wall materials. The new constitutive description of polyurethane foam is implemented in both static and dynamic finite element codes, and analytical and numerical predictions are compared with available experimental data.
Prognosis of Different Cellular Generations
Directory of Open Access Journals (Sweden)
Preetish Ranjan
2013-04-01
Full Text Available Technological advancement in mobile telephony from 1G to 3G, 4G and 5G has a very axiomatic fact that made an entire world a global village. The cellular system employs a different design approach and technology that most commercial radio and television system use. In the cellular system, the service area is divided into cells and a transmitter is designed to serve an individual cell. The system seeks to make efficient use of available channels by using low-power transmitters to allow frequency reuse at a smaller distance. Maximizing the number of times each channel can be reused in a given geographical area is the key to an efficient cellular system design. During the past three decades, the world has seen significant changes in telecommunications industry. There have been some remarkable aspects to the rapid growth in wireless communications, as seen by the large expansion in mobile systems. This paper focuses on “Past, Present & Future of Cellular Telephony” and some light has been thrown upon the technologies of the cellular systems, namely 1G, 2G, 2.5G, 3G and future generations like 4G and 5G systems as well.
Aging, cellular senescence, and cancer.
Campisi, Judith
2013-01-01
For most species, aging promotes a host of degenerative pathologies that are characterized by debilitating losses of tissue or cellular function. However, especially among vertebrates, aging also promotes hyperplastic pathologies, the most deadly of which is cancer. In contrast to the loss of function that characterizes degenerating cells and tissues, malignant (cancerous) cells must acquire new (albeit aberrant) functions that allow them to develop into a lethal tumor. This review discusses the idea that, despite seemingly opposite characteristics, the degenerative and hyperplastic pathologies of aging are at least partly linked by a common biological phenomenon: a cellular stress response known as cellular senescence. The senescence response is widely recognized as a potent tumor suppressive mechanism. However, recent evidence strengthens the idea that it also drives both degenerative and hyperplastic pathologies, most likely by promoting chronic inflammation. Thus, the senescence response may be the result of antagonistically pleiotropic gene action. PMID:23140366
Institute of Scientific and Technical Information of China (English)
李锰; 杨峰; 胡伟华
2011-01-01
为解释实际观测资料震源破裂过程与自相似(分形)模型的不一致性,本文基于观测结果,构建了由81×81个细胞单元组成二维非均匀断层模型,并通过设计的细胞自动机模拟程序进行了模拟试验.研究结果表明:断层结构非均匀性是影响孕震过程特征的重要因素,而且地震强度分布并非简单的自相似.随着断层非匀质性增加,破裂过程出现由相对的脆性破坏向塑性破坏特征变化的趋势.利用细胞自动机不仅能较好地解释震级-频度关系中的大、小震级段低头现象,而且也可解释大震级事件具有相对恒定的应力降,得到了与实际观测研究相一致的结果.%In the paper, three kinds of heterogeneous faults with 81 ×81 cells are set up using celluar automata models and simulated for explaining the inconsistency between the observations and fractal-based model. The results show that the G-R relations behave not in simple self-similarity but multi-fractal, and with the increasing of heterogeneity the fracture process tends to turn from brittle to plastic behaviors. At the same time, using the models can explain not only the curvature at smaller and larger magnitudes in G-R relation but also the relatively constant stress drop for larger magnitude earthquake events.Fault structural heterogeneity plays a important role in earthquake preparation process.The results from computer simulation are consistent with observations from detailed seismicity studies.
Evolving Transport Networks With Cellular Automata Models Inspired by Slime Mould.
Tsompanas, Michail-Antisthenis I; Sirakoulis, Georgios Ch; Adamatzky, Andrew I
2015-09-01
Man-made transport networks and their design are closely related to the shortest path problem and considered amongst the most debated problems of computational intelligence. Apart from using conventional or bio-inspired computer algorithms, many researchers tried to solve this kind of problem using biological computing substrates, gas-discharge solvers, prototypes of a mobile droplet, and hot ice computers. In this aspect, another example of biological computer is the plasmodium of acellular slime mould Physarum polycephalum (P. polycephalum), which is a large single cell visible by an unaided eye and has been proven as a reliable living substrate for implementing biological computing devices for computational geometry, graph-theoretical problems, and optimization and imitation of transport networks. Although P. polycephalum is easy to experiment with, computing devices built with the living slime mould are extremely slow; it takes slime mould days to execute a computation. Consequently, mapping key computing mechanisms of the slime mould onto silicon would allow us to produce efficient bio-inspired computing devices to tackle with hard to solve computational intelligence problems like the aforementioned. Toward this direction, a cellular automaton (CA)-based, Physarum-inspired, network designing model is proposed. This novel CA-based model is inspired by the propagating strategy, the formation of tubular networks, and the computing abilities of the plasmodium of P. polycephalum. The results delivered by the CA model demonstrate a good match with several previously published results of experimental laboratory studies on imitation of man-made transport networks with P. polycephalum. Consequently, the proposed CA model can be used as a virtual, easy-to-access, and biomimicking laboratory emulator that will economize large time periods needed for biological experiments while producing networks almost identical to the tubular networks of the real-slime mould. PMID
Adaptive stochastic cellular automata: Applications
Qian, S.; Lee, Y. C.; Jones, R. D.; Barnes, C. W.; Flake, G. W.; O'Rourke, M. K.; Lee, K.; Chen, H. H.; Sun, G. Z.; Zhang, Y. Q.; Chen, D.; Giles, C. L.
1990-09-01
The stochastic learning cellular automata model has been applied to the problem of controlling unstable systems. Two example unstable systems studied are controlled by an adaptive stochastic cellular automata algorithm with an adaptive critic. The reinforcement learning algorithm and the architecture of the stochastic CA controller are presented. Learning to balance a single pole is discussed in detail. Balancing an inverted double pendulum highlights the power of the stochastic CA approach. The stochastic CA model is compared to conventional adaptive control and artificial neural network approaches.
Cellular senescence in aging primates.
Herbig, Utz; Ferreira, Mark; Condel, Laura; Carey, Dee; Sedivy, John M
2006-03-01
The aging of organisms is characterized by a gradual functional decline of all organ systems. Mammalian somatic cells in culture display a limited proliferative life span, at the end of which they undergo an irreversible cell cycle arrest known as replicative senescence. Whether cellular senescence contributes to organismal aging has been controversial. We investigated telomere dysfunction, a recently discovered biomarker of cellular senescence, and found that the number of senescent fibroblasts increases exponentially in the skin of aging baboons, reaching >15% of all cells in very old individuals. In addition, the same cells contain activated ataxia-telangiectasia mutated kinase and heterochromatinized nuclei, confirming their senescent status. PMID:16456035
Repaglinide at a cellular level
DEFF Research Database (Denmark)
Krogsgaard Thomsen, M; Bokvist, K; Høy, M;
2002-01-01
To investigate the hormonal and cellular selectivity of the prandial glucose regulators, we have undertaken a series of experiments, in which we characterised the effects of repaglinide and nateglinide on ATP-sensitive potassium ion (KATP) channel activity, membrane potential and exocytosis in ra...
Analysis of cellular manufacturing systems
Heragu, Sunderesh; Meng, Gang; Zijm, Henk; Ommeren, van Jan-Kees
2001-01-01
In this paper, we present an open queuing network modeling approach to estimate performance measures of a cellular manufacturing layout. It is assumed a layout and production data for a planning period of specified length are available. The production data takes into account, processing and handli
Cellular uptake of metallated cobalamins
DEFF Research Database (Denmark)
Tran, MQT; Stürup, Stefan; Lambert, Ian H.;
2016-01-01
Cellular uptake of vitamin B12-cisplatin conjugates was estimated via detection of their metal constituents (Co, Pt, and Re) by inductively coupled plasma mass spectrometry (ICP-MS). Vitamin B12 (cyano-cob(iii)alamin) and aquo-cob(iii)alamin [Cbl-OH2](+), which differ in the β-axial ligands (CN(-...
Modeling the topological organization of cellular processes.
Giavitto, Jean-Louis; Michel, Olivier
2003-07-01
The cell as a dynamical system presents the characteristics of having a dynamical structure. That is, the exact phase space of the system cannot be fixed before the evolution and integrative cell models must state the evolution of the structure jointly with the evolution of the cell state. This kind of dynamical systems is very challenging to model and simulate. New programming concepts must be developed to ease their modeling and simulation. In this context, the goal of the MGS project is to develop an experimental programming language dedicated to the simulation of this kind of systems. MGS proposes a unified view on several computational mechanisms (CHAM, Lindenmayer systems, Paun systems, cellular automata) enabling the specification of spatially localized computations on heterogeneous entities. The evolution of a dynamical structure is handled through the concept of transformation which relies on the topological organization of the system components. An example based on the modeling of spatially distributed biochemical networks is used to illustrate how these notions can be used to model the spatial and temporal organization of intracellular processes. PMID:12915272
Modeling chemical systems using cellular automata a textbook and laboratory manual
Kier, Lemont B; Cheng, Chao-Kun
2006-01-01
Provides a practical introduction to an exciting modeling paradigm for complex systems. This book discusses the nature of scientific inquiry using models and simulations, and describes the nature of cellular automata models. It gives descriptions of how cellular automata models can be used in the study of a variety of phenomena.
Cellular Automata Models for Diffusion of Innovations
Fuks, H; Fuks, Henryk; Boccara, Nino
1997-01-01
We propose a probabilistic cellular automata model for the spread of innovations, rumors, news, etc. in a social system. The local rule used in the model is outertotalistic, and the range of interaction can vary. When the range R of the rule increases, the takeover time for innovation increases and converges toward its mean-field value, which is almost inversely proportional to R when R is large. Exact solutions for R=1 and $R=\\infty$ (mean-field) are presented, as well as simulation results for other values of R. The average local density is found to converge to a certain stationary value, which allows us to obtain a semi-phenomenological solution valid in the vicinity of the fixed point n=1 (for large t).
Traffic jam dynamics in stochastic cellular automata
Energy Technology Data Exchange (ETDEWEB)
Nagel, K. [Los Alamos National Lab., NM (United States)]|[Santa Fe Inst., NM (United States); Schreckenberg, M. [Univ. Duisburg (Germany)
1995-09-01
Simple models for particles hopping on a grid (cellular automata) are used to simulate (single lane) traffic flow. Despite their simplicity, these models are astonishingly realistic in reproducing start-stop-waves and realistic fundamental diagrams. One can use these models to investigate traffic phenomena near maximum flow. A so-called phase transition at average maximum flow is visible in the life-times of jams. The resulting dynamic picture is consistent with recent fluid-dynamical results by Kuehne/Kerner/Konhaeuser, and with Treiterer`s hysteresis description. This places CA models between car-following models and fluid-dynamical models for traffic flow. CA models are tested in projects in Los Alamos (USA) and in NRW (Germany) for large scale microsimulations of network traffic.
Institute of Scientific and Technical Information of China (English)
赵明娟; 邓志成; 赵龙志
2015-01-01
基于元胞自动机法，结合 Moore 型邻居定义和晶粒生长理论，建立了增强相颗粒 SiC 对镁合金激光熔注中表层316L不锈钢晶粒生长的影响模型，模型考虑了晶界迁移率和晶界能等因素，实现了不同增强相颗粒体积分数和颗粒尺寸对晶粒生长影响的计算机模拟.结果表明，所建立的模型能较好的模拟晶粒生长过程，所得晶粒生长指数为0．42；增强相颗粒体积分数含量越高，晶粒生长越慢，晶粒尺寸越小；增强相颗粒尺寸越小，晶粒生长的越慢，晶粒尺寸越小，组织越均匀.%Based on the cellular automaton method,the definition of Moore neighbor type and the grain growth theory,a model of simulation for the grain growth process was established,which simulated the influence of the SiC reinforcement particles and 316L stainless steel reinforced the surface of magnesium alloy by laser melt inj ection.Many factors such as grain boundary mobility and grain boundary energy were considered in the mod-el.Simulated the influence of different volume fraction and size of reinforcement particles on the grain growth process were obtained.The results show that:the grain growth process can be simulated very well by the meth-od,the grain growth index can be obtained as 0.42;the higher volume fraction of the particles,the slower the speed of the grain growth,the smaller grain size;the smaller the particles size is,the slower the grain grows, the smaller grain size and the microstructure is more uniform.
Cellular solidification of transparent monotectics
Kaulker, W. F.
1986-01-01
Understanding how liquid phase particles are engulfed or pushed during freezing of a monotectic is addressed. The additional complication is that the solid-liquid interface is nonplanar due to constitutional undercooling. Some evidence of particle pushing where the particles are the liquid phase of the montectic was already observed. Cellular freezing of the succinonitrile-glycerol system also occurred. Only a few compositions were tested at that time. The starting materials were not especially pure so that cellular interface observed was likely due to the presence of unkown impurities, the major portion of which was water. Topics addressed include: the effort of modeling the particle pushing process using the computer, establishing an apparatus for the determination of phase diagrams, and the measurement of the temperature gradients with a specimen which will solidify on the temperature gradient microscope stage.
Reversibly assembled cellular composite materials.
Cheung, Kenneth C; Gershenfeld, Neil
2013-09-13
We introduce composite materials made by reversibly assembling a three-dimensional lattice of mass-produced carbon fiber-reinforced polymer composite parts with integrated mechanical interlocking connections. The resulting cellular composite materials can respond as an elastic solid with an extremely large measured modulus for an ultralight material (12.3 megapascals at a density of 7.2 milligrams per cubic centimeter). These materials offer a hierarchical decomposition in modeling, with bulk properties that can be predicted from component measurements and deformation modes that can be determined by the placement of part types. Because site locations are locally constrained, structures can be produced in a relative assembly process that merges desirable features of fiber composites, cellular materials, and additive manufacturing.
Error performance analysis in downlink cellular networks with interference management
Afify, Laila H.
2015-05-01
Modeling aggregate network interference in cellular networks has recently gained immense attention both in academia and industry. While stochastic geometry based models have succeeded to account for the cellular network geometry, they mostly abstract many important wireless communication system aspects (e.g., modulation techniques, signal recovery techniques). Recently, a novel stochastic geometry model, based on the Equivalent-in-Distribution (EiD) approach, succeeded to capture the aforementioned communication system aspects and extend the analysis to averaged error performance, however, on the expense of increasing the modeling complexity. Inspired by the EiD approach, the analysis developed in [1] takes into consideration the key system parameters, while providing a simple tractable analysis. In this paper, we extend this framework to study the effect of different interference management techniques in downlink cellular network. The accuracy of the proposed analysis is verified via Monte Carlo simulations.
The brittleness model of complex system based on cellular automata
Institute of Scientific and Technical Information of China (English)
LIN De-ming; JIN Hong-zhang; LI Qi; WU Hong-mei
2004-01-01
Now the research on the complex system is a hot spot. Brittleness is one of the basic characteristics of a complex system. In a complex system, after one of subsystems is struck to be collapsed, the whole system will collapse. Meanwhile, cellular automata is a discrete dynamic system. When the rule is given, the cellular automata could be defined. Then it can imitate the complex action. Cellular automata is used to simulate the brittleness action in this study. Entropy was used to analyze the action and get the rule. Then,three normal brittleness models were given. The result shows that the brittleness of complex system is existent and in addition some important behavior mode of complex system brittleness has been achieved.
Analysis of cellular manufacturing systems
Heragu, Sunderesh; Meng, Gang; Zijm, Henk; Ommeren, van, J.C.
2001-01-01
In this paper, we present an open queuing network modeling approach to estimate performance measures of a cellular manufacturing layout. It is assumed a layout and production data for a planning period of specified length are available. The production data takes into account, processing and handling set-up times as well as transfer and process batch size information of multiple products that flow through the system. It is assumed that two sets of discrete material handling devices are used fo...
Identification of Nonstationary Cellular Automata
Institute of Scientific and Technical Information of China (English)
AndrewI.Adamatzky
1992-01-01
The principal feature of nonstationary cellular automata(NCA) is that a local transitiol rule of each cell is changed at each time step depending on neighborhood configuration at previous time step.The identification problem for NCA is extraction of local transition rules and the establishment of mechanism for changing these rules using sequence of NCA configurations.We present serial and parallel algorithms for identification of NCA.
Schrum, Jason P.; Zhu, Ting F.; SZOSTAK, JACK W.
2010-01-01
Understanding the origin of cellular life on Earth requires the discovery of plausible pathways for the transition from complex prebiotic chemistry to simple biology, defined as the emergence of chemical assemblies capable of Darwinian evolution. We have proposed that a simple primitive cell, or protocell, would consist of two key components: a protocell membrane that defines a spatially localized compartment, and an informational polymer that allows for the replication and inheritance of fun...
CELLULAR FETAL MICROCHIMERISM IN PREECLAMPSIA
Gammill, Hilary S; Aydelotte, Tessa M.; Guthrie, Katherine A.; Nkwopara, Evangelyn C.; Nelson, J. Lee
2013-01-01
Previous studies have shown elevated concentrations of free fetal deoxyribonucleic acid and erythroblasts in maternal circulation in preeclampsia compared with normal pregnancy. Pluripotent and immunocompetent fetal cells also transfer to the maternal circulation during pregnancy, but whether concentrations of fetal mononuclear cells also differed in preeclampsia was unknown. We sought to quantify cellular fetal microchimerism in maternal circulation in women with preeclampsia and healthy con...
Cellular reactions to patterned biointerfaces
Schulte, Vera Antonie
2012-01-01
The subject of this thesis is to study cellular reactions to topographically, mechanically and biochemically tunable polymeric biomaterials. Different aspects of in vitro cell-biomaterial interactions were systematically studied with the murine fibroblast cell line NIH L929 and primary human dermal fibroblasts (HDFs). Besides a general cytocompatibility assessment of the applied materials and the quantification of cell adhesion per se, cell morphological changes (e.g. cell spreading) and intr...
CELLULAR INTERACTIONS MEDIATED BY GLYCONECTIDS
Popescu, O.; Sumanovski, L. T.; I. Checiu; Elisabeta Popescu; G. N. Misevic
1999-01-01
Cellular interactions involve many types of cell surface molecules and operate via homophilic and/or heterophilic protein-protein and protein-carbohydrate binding. Our investigations in different model-systems (marine invertebrates and mammals) have provided direct evidence that a novel class of primordial proteoglycans, named by us gliconectins, can mediate cell adhesion via a new alternative molecular mechanism of polyvalent carbohydrate-carbohydrate binding. Biochemical characterization of...
A cellular automata evacuation model considering friction and repulsion
Institute of Scientific and Technical Information of China (English)
SONG Weiguo; YU Yanfei; FAN Weicheng; Zhang Heping
2005-01-01
There exist interactions among pedestrians and between pedestrian and environment in evacuation. These interactions include attraction, repulsion and friction that play key roles in human evacuation behaviors, speed and efficiency. Most former evacuation models focus on the attraction force, while repulsion and friction are not well modeled. As a kind of multi-particle self-driven model, the social force model introduced in recent years can represent those three forces but with low simulation efficiency because it is a continuous model with complex rules. Discrete models such as the cellular automata model and the lattice gas model have simple rules and high simulation efficiency, but are not quite suitable for interactions' simulation. In this paper, a new cellular automata model based on traditional models is introduced in which repulsion and friction are modeled quantitatively. It is indicated that the model can simulate some basic behaviors, e.g.arching and the "faster-is-slower" phenomenon, in evacuation as multi-particle self-driven models, but with high efficiency as the normal cellular automata model and the lattice gas model.
Progress of cellular dedifferentiation research
Institute of Scientific and Technical Information of China (English)
LIU Hu-xian; HU Da-hai; JIA Chi-yu; FU Xiao-bing
2006-01-01
Differentiation, the stepwise specialization of cells, and transdifferentiation, the apparent switching of one cell type into another, capture much of the stem cell spotlight. But dedifferentiation, the developmental reversal of a cell before it reinvents itself, is an important process too. In multicellular organisms, cellular dedifferentiation is the major process underlying totipotency, regeneration and formation of new stem cell lineages. In humans,dedifferentiation is often associated with carcinogenesis.The study of cellular dedifferentiation in animals,particularly early events related to cell fate-switch and determination, is limited by the lack of a suitable,convenient experimental system. The classic example of dedifferentiation is limb and tail regeneration in urodele amphibians, such as salamanders. Recently, several investigators have shown that certain mammalian cell types can be induced to dedifferentiate to progenitor cells when stimulated with the appropriate signals or materials. These discoveries open the possibility that researchers might enhance the endogenous regenerative capacity of mammals by inducing cellular dedifferentiation in vivo.
The insect cellular immune response
Institute of Scientific and Technical Information of China (English)
Michael R. Strand
2008-01-01
The innate immune system of insects is divided into humoral defenses that include the production of soluble effector molecules and cellular defenses like phagocytosis and encapsulation that are mediated by hemocytes. This review summarizes current understanding of the cellular immune response. Insects produce several terminally differentiated types of hemocytes that are distinguished by morphology, molecular and antigenic markers, and function. The differentiated hemocytes that circulate in larval or nymphal stage insects arise from two sources: progenitor cells produced during embryogenesis and mesodermally derived hematopoietic organs. Regulation of hematopoiesis and hemocyte differentiation also involves several different signaling pathways. Phagocytosis and encapsulation require that hemocytes first recognize a given target as foreign followed by activation of downstream signaling and effector responses. A number of humoral and cellular receptors have been identified that recognize different microbes and multicellular parasites. In turn, activation of these receptors stimulates a number of signaling pathways that regulate different hemocyte functions. Recent studies also identify hemocytes as important sources of a number of humoral effector molecules required for killing different foreign invaders.
Cellular communications a comprehensive and practical guide
Tripathi, Nishith
2014-01-01
Even as newer cellular technologies and standards emerge, many of the fundamental principles and the components of the cellular network remain the same. Presenting a simple yet comprehensive view of cellular communications technologies, Cellular Communications provides an end-to-end perspective of cellular operations, ranging from physical layer details to call set-up and from the radio network to the core network. This self-contained source forpractitioners and students represents a comprehensive survey of the fundamentals of cellular communications and the landscape of commercially deployed
Integration of Neural Networks and Cellular Automata for Urban Planning
Institute of Scientific and Technical Information of China (English)
Anthony Gar-on Yeh; LI Xia
2004-01-01
This paper presents a new type of cellular automata (CA) model for the simulation of alternative land development using neural networks for urban planning. CA models can be regarded as a planning tool because they can generate alternative urban growth. Alternative development patterns can be formed by using different sets of parameter values in CA simulation. A critical issue is how to define parameter values for realistic and idealized simulation. This paper demonstrates that neural networks can simplify CA models but generate more plausible results. The simulation is based on a simple three-layer network with an output neuron to generate conversion probability. No transition rules are required for the simulation. Parameter values are automatically obtained from the training of network by using satellite remote sensing data. Original training data can be assessed and modified according to planning objectives. Alternative urban patterns can be easily formulated by using the modified training data sets rather than changing the model.
Krbalek, M
2003-01-01
We present a cellular automaton simulating the behaviour of public bus transport in several Mexican cities. The headway statistics obtained from the model is compared to the measured time intervals between subsequent bus arrivals to a given bus stop and to a spacing distribution resulting from a random matrix theory. (letter to the editor)
Gordienko, Yuriy G
2015-01-01
The cellular automaton model is used to simulate diffusion and aggregation with dissociation of point particles in 2D. A continuous phase transition is found that separates creation of compact aggregates and fractal ones. The transition is the function of pair-interaction energy ($E_b$), type of neighborhood and temperature $T$. Manifestations of the transition in real physical systems are discussed.
Optimal flux patterns in cellular metabolic networks
Energy Technology Data Exchange (ETDEWEB)
Almaas, E
2007-01-20
The availability of whole-cell level metabolic networks of high quality has made it possible to develop a predictive understanding of bacterial metabolism. Using the optimization framework of flux balance analysis, I investigate metabolic response and activity patterns to variations in the availability of nutrient and chemical factors such as oxygen and ammonia by simulating 30,000 random cellular environments. The distribution of reaction fluxes is heavy-tailed for the bacteria H. pylori and E. coli, and the eukaryote S. cerevisiae. While the majority of flux balance investigations have relied on implementations of the simplex method, it is necessary to use interior-point optimization algorithms to adequately characterize the full range of activity patterns on metabolic networks. The interior-point activity pattern is bimodal for E. coli and S. cerevisiae, suggesting that most metabolic reaction are either in frequent use or are rarely active. The trimodal activity pattern of H. pylori indicates that a group of its metabolic reactions (20%) are active in approximately half of the simulated environments. Constructing the high-flux backbone of the network for every environment, there is a clear trend that the more frequently a reaction is active, the more likely it is a part of the backbone. Finally, I briefly discuss the predicted activity patterns of the central-carbon metabolic pathways for the sample of random environments.
Cellular host responses to gliomas.
Directory of Open Access Journals (Sweden)
Joseph Najbauer
Full Text Available BACKGROUND: Glioblastoma multiforme (GBM is the most aggressive type of malignant primary brain tumors in adults. Molecular and genetic analysis has advanced our understanding of glioma biology, however mapping the cellular composition of the tumor microenvironment is crucial for understanding the pathology of this dreaded brain cancer. In this study we identified major cell populations attracted by glioma using orthotopic rodent models of human glioma xenografts. Marker-specific, anatomical and morphological analyses revealed a robust influx of host cells into the main tumor bed and tumor satellites. METHODOLOGY/PRINCIPAL FINDINGS: Human glioma cell lines and glioma spheroid orthotopic implants were used in rodents. In both models, the xenografts recruited large numbers of host nestin-expressing cells, which formed a 'network' with glioma. The host nestin-expressing cells appeared to originate in the subventricular zone ipsilateral to the tumor, and were clearly distinguishable from pericytes that expressed smooth muscle actin. These distinct cell populations established close physical contact in a 'pair-wise' manner and migrated together to the deeper layers of tumor satellites and gave rise to tumor vasculature. The GBM biopsy xenografts displayed two different phenotypes: (a low-generation tumors (first in vivo passage in rats were highly invasive and non-angiogenic, and host nestin-positive cells that infiltrated into these tumors displayed astrocytic or elongated bipolar morphology; (b high-generation xenografts (fifth passage had pronounced cellularity, were angiogenic with 'glomerulus-like' microvascular proliferations that contained host nestin-positive cells. Stromal cell-derived factor-1 and its receptor CXCR4 were highly expressed in and around glioma xenografts, suggesting their role in glioma progression and invasion. CONCLUSIONS/SIGNIFICANCE: Our data demonstrate a robust migration of nestin-expressing host cells to glioma, which
Gao, Xin; Narteau, Clément; Rozier, Olivier
2016-03-01
Unlike ripples, there are only few numerical studies on grain size segregation at the scale of dunes in aeolian environments. Here we use a cellular automaton model to analyze vertical sorting in granular mixtures under steady unidirectional flow conditions. We investigate the feedbacks between dune growth and the segregation mechanisms by varying the size of coarse grains and their proportion within the bed. We systematically observe the development of a horizontal layer of coarse grains at the top of which sorted bed forms may grow by amalgamation. The formation of such an armor layer controls the overall sediment transport and availability. The emergence of dunes and the transition from barchan to transverse dune fields depend only on the grain size distribution of the initial sediment layer. As confirmed by observation, this result indicates that armor layers should be present in most arid deserts, where they are likely to control dune morphodynamics.
Estimation in Cellular Radio Systems
Blom, Jonas; Gunnarsson, Fredrik; Gustafsson, Fredrik
1999-01-01
The problem to track time-varying parameters in cellular radio systems is studied, and the focus is on estimation based only on the signals that are readily available. Previous work have demonstrated very good performance, but were relying on analog measurement that are not available. Most of the information is lost due to quantization and sampling at a rate that might be as low as 2 Hz (GSM case). For that matter a maximum likelihood estimator have been designed and exemplified in the case o...
Cellular immune responses to HIV
McMichael, Andrew J.; Rowland-Jones, Sarah L.
2001-04-01
The cellular immune response to the human immunodeficiency virus, mediated by T lymphocytes, seems strong but fails to control the infection completely. In most virus infections, T cells either eliminate the virus or suppress it indefinitely as a harmless, persisting infection. But the human immunodeficiency virus undermines this control by infecting key immune cells, thereby impairing the response of both the infected CD4+ T cells and the uninfected CD8+ T cells. The failure of the latter to function efficiently facilitates the escape of virus from immune control and the collapse of the whole immune system.
Cellular automata a parallel model
Mazoyer, J
1999-01-01
Cellular automata can be viewed both as computational models and modelling systems of real processes. This volume emphasises the first aspect. In articles written by leading researchers, sophisticated massive parallel algorithms (firing squad, life, Fischer's primes recognition) are treated. Their computational power and the specific complexity classes they determine are surveyed, while some recent results in relation to chaos from a new dynamic systems point of view are also presented. Audience: This book will be of interest to specialists of theoretical computer science and the parallelism challenge.
Protein accounting in the cellular economy
Vázquez-Laslop, Nora; Mankin, Alexander S.
2014-01-01
Knowing the copy number of cellular proteins is critical for understanding cell physiology. By being able to measure the absolute synthesis rates of the majority of cellular proteins, Li et al. (2014) gain insights into key aspects of translation regulation and fundamental principles of cellular strategies to adjust protein synthesis according to the needs. PMID:24766801
Cellular uptake of metallated cobalamins.
Tran, Mai Thanh Quynh; Stürup, Stefan; Lambert, Ian Henry; Gammelgaard, Bente; Furger, Evelyne; Alberto, Roger
2016-03-01
Cellular uptake of vitamin B12-cisplatin conjugates was estimated via detection of their metal constituents (Co, Pt, and Re) by inductively coupled plasma mass spectrometry (ICP-MS). Vitamin B12 (cyano-cob(iii)alamin) and aquo-cob(iii)alamin [Cbl-OH2](+), which differ in the β-axial ligands (CN(-) and H2O, respectively), were included as control samples. The results indicated that B12 derivatives delivered cisplatin to both cellular cytosol and nuclei with an efficiency of one third compared to the uptake of free cisplatin cis-[Pt(II)Cl2(NH3)2]. In addition, uptake of charged B12 derivatives including [Cbl-OH2](+), [{Co}-CN-{cis-PtCl(NH3)2}](+), [{Re}-{Co}-CN-{cis-PtCl(NH3)2}](+), and [{Co}-CN-{trans-Pt(Cyt)(NH3)2}](2+) (Cyt = cytarabin) was high compared to neutral B12, which implied the existence of an additional internalization pathway for charged B12 vitamin analogs. The affinities of the charged B12 derivatives to the B12 transporters HC, IF and TC were similar to that of native vitamin B12. PMID:26739575
Cellular Therapy for Heart Failure.
Psaltis, Peter J; Schwarz, Nisha; Toledo-Flores, Deborah; Nicholls, Stephen J
2016-01-01
The pathogenesis of cardiomyopathy and heart failure (HF) is underpinned by complex changes at subcellular, cellular and extracellular levels in the ventricular myocardium. For all of the gains that conventional treatments for HF have brought to mortality and morbidity, they do not adequately address the loss of cardiomyocyte numbers in the remodeling ventricle. Originally conceived to address this problem, cellular transplantation for HF has already gone through several stages of evolution over the past two decades. Various cell types and delivery routes have been implemented to positive effect in preclinical models of ischemic and nonischemic cardiomyopathy, with pleiotropic benefits observed in terms of myocardial remodeling, systolic and diastolic performance, perfusion, fibrosis, inflammation, metabolism and electrophysiology. To a large extent, these salubrious effects are now attributed to the indirect, paracrine capacity of transplanted stem cells to facilitate endogenous cardiac repair processes. Promising results have also followed in early phase human studies, although these have been relatively modest and somewhat inconsistent. This review details the preclinical and clinical evidence currently available regarding the use of pluripotent stem cells and adult-derived progenitor cells for cardiomyopathy and HF. It outlines the important lessons that have been learned to this point in time, and balances the promise of this exciting field against the key challenges and questions that still need to be addressed at all levels of research, to ensure that cell therapy realizes its full potential by adding to the armamentarium of HF management. PMID:27280304
Cellular functions of the microprocessor.
Macias, Sara; Cordiner, Ross A; Cáceres, Javier F
2013-08-01
The microprocessor is a complex comprising the RNase III enzyme Drosha and the double-stranded RNA-binding protein DGCR8 (DiGeorge syndrome critical region 8 gene) that catalyses the nuclear step of miRNA (microRNA) biogenesis. DGCR8 recognizes the RNA substrate, whereas Drosha functions as an endonuclease. Recent global analyses of microprocessor and Dicer proteins have suggested novel functions for these components independent of their role in miRNA biogenesis. A HITS-CLIP (high-throughput sequencing of RNA isolated by cross-linking immunoprecipitation) experiment designed to identify novel substrates of the microprocessor revealed that this complex binds and regulates a large variety of cellular RNAs. The microprocessor-mediated cleavage of several classes of RNAs not only regulates transcript levels, but also modulates alternative splicing events, independently of miRNA function. Importantly, DGCR8 can also associate with other nucleases, suggesting the existence of alternative DGCR8 complexes that may regulate the fate of a subset of cellular RNAs. The aim of the present review is to provide an overview of the diverse functional roles of the microprocessor.
Universal map for cellular automata
Energy Technology Data Exchange (ETDEWEB)
García-Morales, V., E-mail: vmorales@ph.tum.de [Institute for Advanced Study – Technische Universität München, Lichtenbergstr. 2a, D-85748 Garching (Germany)
2012-08-20
A universal map is derived for all deterministic 1D cellular automata (CAs) containing no freely adjustable parameters and valid for any alphabet size and any neighborhood range (including non-symmetrical neighborhoods). The map can be extended to an arbitrary number of dimensions and topologies and to arbitrary order in time. Specific CA maps for the famous Conway's Game of Life and Wolfram's 256 elementary CAs are given. An induction method for CAs, based in the universal map, allows mathematical expressions for the orbits of a wide variety of elementary CAs to be systematically derived. -- Highlights: ► A universal map is derived for all deterministic 1D cellular automata (CA). ► The map is generalized to 2D for Von Neumann, Moore and hexagonal neighborhoods. ► A map for all Wolfram's 256 elementary CAs is derived. ► A map for Conway's “Game of Life” is obtained.
Melanoma screening with cellular phones.
Directory of Open Access Journals (Sweden)
Cesare Massone
Full Text Available BACKGROUND: Mobile teledermatology has recently been shown to be suitable for teledermatology despite limitations in image definition in preliminary studies. The unique aspect of mobile teledermatology is that this system represents a filtering or triage system, allowing a sensitive approach for the management of patients with emergent skin diseases. METHODOLOGY/PRINCIPAL FINDINGS: In this study we investigated the feasibility of teleconsultation using a new generation of cellular phones in pigmented skin lesions. 18 patients were selected consecutively in the Pigmented Skin Lesions Clinic of the Department of Dermatology, Medical University of Graz, Graz (Austria. Clinical and dermoscopic images were acquired using a Sony Ericsson with a built-in two-megapixel camera. Two teleconsultants reviewed the images on a specific web application (http://www.dermahandy.net/default.asp where images had been uploaded in JPEG format. Compared to the face-to-face diagnoses, the two teleconsultants obtained a score of correct telediagnoses of 89% and of 91.5% reporting the clinical and dermoscopic images, respectively. CONCLUSIONS/SIGNIFICANCE: The present work is the first study performing mobile teledermoscopy using cellular phones. Mobile teledermatology has the potential to become an easy applicable tool for everyone and a new approach for enhanced self-monitoring for skin cancer screening in the spirit of the eHealth program of the European Commission Information for Society and Media.
Public Evacuation Process Modeling and Simulatiaon Based on Cellular Automata
Directory of Open Access Journals (Sweden)
Zhikun Wang
2013-11-01
Full Text Available Considering attraction of the nearest exit, repulsive force of the fire, barrier and its display style, effect of fire exit location on escape time in fire hazard, a mathematical model of evacuation process model was build based on cellular automatic theory. The program was developed by JavaScript. The influencing factors of evacuation were obtained through the simulation model by inputting crew size, creating initial positions of crew and fire seat stochastically. The experimental results show that the evacuation simulation model with authenticity and validity, which has guiding significance for people evacuation and public escape system design.
Modeling integrated cellular machinery using hybrid Petri-Boolean networks.
Directory of Open Access Journals (Sweden)
Natalie Berestovsky
Full Text Available The behavior and phenotypic changes of cells are governed by a cellular circuitry that represents a set of biochemical reactions. Based on biological functions, this circuitry is divided into three types of networks, each encoding for a major biological process: signal transduction, transcription regulation, and metabolism. This division has generally enabled taming computational complexity dealing with the entire system, allowed for using modeling techniques that are specific to each of the components, and achieved separation of the different time scales at which reactions in each of the three networks occur. Nonetheless, with this division comes loss of information and power needed to elucidate certain cellular phenomena. Within the cell, these three types of networks work in tandem, and each produces signals and/or substances that are used by the others to process information and operate normally. Therefore, computational techniques for modeling integrated cellular machinery are needed. In this work, we propose an integrated hybrid model (IHM that combines Petri nets and Boolean networks to model integrated cellular networks. Coupled with a stochastic simulation mechanism, the model simulates the dynamics of the integrated network, and can be perturbed to generate testable hypotheses. Our model is qualitative and is mostly built upon knowledge from the literature and requires fine-tuning of very few parameters. We validated our model on two systems: the transcriptional regulation of glucose metabolism in human cells, and cellular osmoregulation in S. cerevisiae. The model produced results that are in very good agreement with experimental data, and produces valid hypotheses. The abstract nature of our model and the ease of its construction makes it a very good candidate for modeling integrated networks from qualitative data. The results it produces can guide the practitioner to zoom into components and interconnections and investigate them
Makovetskiy, S D
2008-01-01
We report some qualitatively new features of emergence, competition and dynamical stabilization of dissipative rotating spiral waves (RSWs) in the cellular-automaton model of laser-like excitable media proposed in arXiv:cond-mat/0410460v2 ; arXiv:cond-mat/0602345 . Part of the observed features are caused by unusual mechanism of excitation vorticity when the RSW's core get into the surface layer of an active medium. Instead of the well known scenario of RSW collapse, which takes place after collision of RSW's core with absorbing boundary, we observed complicated transformations of the core leading to regeneration (nonlinear "reflection" from the boundary) of the RSW or even to birth of several new RSWs in the surface layer. Computer experiments on bottlenecked evolution of such the RSW-ensembles (vortex matter) are reported and a possible explanation of real experiments on spin-lattice relaxation in dilute paramagnets is proposed on the basis of an analysis of the RSWs dynamics. Chimera states in RSW-ensemble...
Time scale of diffusion in molecular and cellular biology
Holcman, D.; Schuss, Z.
2014-05-01
Diffusion is the driver of critical biological processes in cellular and molecular biology. The diverse temporal scales of cellular function are determined by vastly diverse spatial scales in most biophysical processes. The latter are due, among others, to small binding sites inside or on the cell membrane or to narrow passages between large cellular compartments. The great disparity in scales is at the root of the difficulty in quantifying cell function from molecular dynamics and from simulations. The coarse-grained time scale of cellular function is determined from molecular diffusion by the mean first passage time of molecular Brownian motion to a small targets or through narrow passages. The narrow escape theory (NET) concerns this issue. The NET is ubiquitous in molecular and cellular biology and is manifested, among others, in chemical reactions, in the calculation of the effective diffusion coefficient of receptors diffusing on a neuronal cell membrane strewn with obstacles, in the quantification of the early steps of viral trafficking, in the regulation of diffusion between the mother and daughter cells during cell division, and many other cases. Brownian trajectories can represent the motion of a molecule, a protein, an ion in solution, a receptor in a cell or on its membrane, and many other biochemical processes. The small target can represent a binding site or an ionic channel, a hidden active site embedded in a complex protein structure, a receptor for a neurotransmitter on the membrane of a neuron, and so on. The mean time to attach to a receptor or activator determines diffusion fluxes that are key regulators of cell function. This review describes physical models of various subcellular microdomains, in which the NET coarse-grains the molecular scale to a higher cellular-level, thus clarifying the role of cell geometry in determining subcellular function.
Cellular Delivery of RNA Nanoparticles.
Parlea, Lorena; Puri, Anu; Kasprzak, Wojciech; Bindewald, Eckart; Zakrevsky, Paul; Satterwhite, Emily; Joseph, Kenya; Afonin, Kirill A; Shapiro, Bruce A
2016-09-12
RNA nanostructures can be programmed to exhibit defined sizes, shapes and stoichiometries from naturally occurring or de novo designed RNA motifs. These constructs can be used as scaffolds to attach functional moieties, such as ligand binding motifs or gene expression regulators, for nanobiology applications. This review is focused on four areas of importance to RNA nanotechnology: the types of RNAs of particular interest for nanobiology, the assembly of RNA nanoconstructs, the challenges of cellular delivery of RNAs in vivo, and the delivery carriers that aid in the matter. The available strategies for the design of nucleic acid nanostructures, as well as for formulation of their carriers, make RNA nanotechnology an important tool in both basic research and applied biomedical science. PMID:27509068
Discrete geodesics and cellular automata
Arrighi, Pablo
2015-01-01
This paper proposes a dynamical notion of discrete geodesics, understood as straightest trajectories in discretized curved spacetime. The notion is generic, as it is formulated in terms of a general deviation function, but readily specializes to metric spaces such as discretized pseudo-riemannian manifolds. It is effective: an algorithm for computing these geodesics naturally follows, which allows numerical validation---as shown by computing the perihelion shift of a Mercury-like planet. It is consistent, in the continuum limit, with the standard notion of timelike geodesics in a pseudo-riemannian manifold. Whether the algorithm fits within the framework of cellular automata is discussed at length. KEYWORDS: Discrete connection, parallel transport, general relativity, Regge calculus.
Cellular compartmentalization of secondary metabolism
Directory of Open Access Journals (Sweden)
H. Corby eKistler
2015-02-01
Full Text Available Fungal secondary metabolism is often considered apart from the essential housekeeping functions of the cell. However, there are clear links between fundamental cellular metabolism and the biochemical pathways leading to secondary metabolite synthesis. Besides utilizing key biochemical precursors shared with the most essential processes of the cell (e.g. amino acids, acetyl CoA, NADPH, enzymes for secondary metabolite synthesis are compartmentalized at conserved subcellular sites that position pathway enzymes to use these common biochemical precursors. Co-compartmentalization of secondary metabolism pathway enzymes also may function to channel precursors, promote pathway efficiency and sequester pathway intermediates and products from the rest of the cell. In this review we discuss the compartmentalization of three well-studied fungal secondary metabolite biosynthetic pathways for penicillin G, aflatoxin and deoxynivalenol, and summarize evidence used to infer subcellular localization. We also discuss how these metabolites potentially are trafficked within the cell and may be exported.
Thermomechanical characterisation of cellular rubber
Seibert, H.; Scheffer, T.; Diebels, S.
2016-09-01
This contribution discusses an experimental possibility to characterise a cellular rubber in terms of the influence of multiaxiality, rate dependency under environmental temperature and its behaviour under hydrostatic pressure. In this context, a mixed open and closed cell rubber based on an ethylene propylene diene monomer is investigated exemplarily. The present article intends to give a general idea of the characterisation method and the considerable effects of this special type of material. The main focus lies on the experimental procedure and the used testing devices in combination with the analysis methods such as true three-dimensional digital image correlation. The structural compressibility is taken into account by an approach for a material model using the Theory of Porous Media with additional temperature dependence.
Novel Materials for Cellular Nanosensors
DEFF Research Database (Denmark)
Sasso, Luigi
modifications for electrochemical nanosensors for the detection of analytes released from cells. Two type of materials were investigated, each pertaining to the two different aspects of such devices: peptide nanostructures were studied for the creation of cellular sensing substrates that mimic in vivo surfaces......' functionalization with biomolecules, metal nanoparticles and chemical functional groups such as thiols, showing the versatility and flexibility of this material's applications. A technique for the patterning of these nanostructures using soft lithography was also developed and tested for suitable cell sensing....... An in vivo investigation also gave evidence of how the peptide nanowires can be used as surface modification in implantable electrodes for neurological measurements. Conducting polymers were utilized in electrode modifications for electrochemical sensor surfaces. Both chemical and electrochemical deposition...
Gateway Deployment optimization in Cellular Wi-Fi Mesh Networks
Directory of Open Access Journals (Sweden)
Rajesh Prasad
2006-07-01
Full Text Available With the standardization of IEEE 802.11, there has been an explosive growth of wireless local area networks (WLAN. Recently, this cost effective technology is being developed aggressively for establishing metro-scale “cellular Wi-Fi” network to support seamless Internet access in the urban area. We envision a large scale WLAN system in the future where Access Points (APs will be scattered over an entire city enabling people to use their mobile devices ubiquitously. The problem addressed in this paper involves finding the minimum number of gateways and their optimal placement so as to minimize the network installation costs while maintaining reliability, flexibility and an acceptable grade of service. The problem is modeled taking a network graph, where the nodes represents either the Access Points of IEEE 802.11 or wired backbone gateways. In this paper, we present two methods (1 an innovative approach using integer linear programming (ILP for gateway selection in the cellular Wi-Fi network, and (2 a completely new heuristic (OPEN/CLOSE to solve the gateway selection problem. In the ILP model, we developed a set of linear inequalities based on various constraints. The ILP model is solved by using lp-solve, a simplex-based software for linear and integer programming problems. The second approach is an OPEN/CLOSE heuristic, tailored for cellular Wi-Fi, which arrives at a sub-optimal solution. Java programming language is used for simulation in OPEN/CLOSE heuristic. Extensive simulations are carried out for performance evaluation. Simulation results show that the proposed approaches can effectively identify a set of gateways at optimal locations in a cellular Wi-Fi network, resulting in an overall cost reduction of up to 50%. The technique presented in this paper is generalized and can be used for gateway selection for other networks as well.
Return of the Quantum Cellular Automata: Episode VI
Carr, Lincoln D.; Hillberry, Logan E.; Rall, Patrick; Halpern, Nicole Yunger; Bao, Ning; Montangero, Simone
2016-05-01
There are now over 150 quantum simulators or analog quantum computers worldwide. Although exploring quantum phase transitions, many-body localization, and the generalized Gibbs ensemble are exciting and worthwhile endeavors, there are totally untapped directions we have not yet pursued. One of these is quantum cellular automata. In the past a principal goal of quantum cellular automata was to reproduce continuum single particle quantum physics such as the Schrodinger or Dirac equation from simple rule sets. Now that we begin to really understand entanglement and many-body quantum physics at a deeper level, quantum cellular automata present new possibilities. We explore several time evolution schemes on simple spin chains leading to high degrees of quantum complexity and nontrivial quantum dynamics. We explain how the 256 known classical elementary cellular automata reduce to just a few exciting quantum cases. Our analysis tools include mutual information based complex networks as well as more familiar quantifiers like sound speed and diffusion rate. Funded by NSF and AFOSR.
Analytical Modeling of Uplink Cellular Networks
Novlan, Thomas D; Andrews, Jeffrey G
2012-01-01
Cellular uplink analysis has typically been undertaken by either a simple approach that lumps all interference into a single deterministic or random parameter in a Wyner-type model, or via complex system level simulations that often do not provide insight into why various trends are observed. This paper proposes a novel middle way that is both accurate and also results in easy-to-evaluate integral expressions based on the Laplace transform of the interference. We assume mobiles and base stations are randomly placed in the network with each mobile pairing up to its closest base station. The model requires two important changes compared to related recent work on the downlink. First, dependence is introduced between the user and base station point processes to make sure each base station serves a single mobile in the given resource block. Second, per-mobile power control is included, which further couples the locations of the mobiles and their receiving base stations. Nevertheless, we succeed in deriving the cov...
Myokit: A simple interface to cardiac cellular electrophysiology.
Clerx, Michael; Collins, Pieter; de Lange, Enno; Volders, Paul G A
2016-01-01
Myokit is a new powerful and versatile software tool for modeling and simulation of cardiac cellular electrophysiology. Myokit consists of an easy-to-read modeling language, a graphical user interface, single and multi-cell simulation engines and a library of advanced analysis tools accessible through a Python interface. Models can be loaded from Myokit's native file format or imported from CellML. Model export is provided to C, MATLAB, CellML, CUDA and OpenCL. Patch-clamp data can be imported and used to estimate model parameters. In this paper, we review existing tools to simulate the cardiac cellular action potential to find that current tools do not cater specifically to model development and that there is a gap between easy-to-use but limited software and powerful tools that require strong programming skills from their users. We then describe Myokit's capabilities, focusing on its model description language, simulation engines and import/export facilities in detail. Using three examples, we show how Myokit can be used for clinically relevant investigations, multi-model testing and parameter estimation in Markov models, all with minimal programming effort from the user. This way, Myokit bridges a gap between performance, versatility and user-friendliness.
Myokit: A simple interface to cardiac cellular electrophysiology.
Clerx, Michael; Collins, Pieter; de Lange, Enno; Volders, Paul G A
2016-01-01
Myokit is a new powerful and versatile software tool for modeling and simulation of cardiac cellular electrophysiology. Myokit consists of an easy-to-read modeling language, a graphical user interface, single and multi-cell simulation engines and a library of advanced analysis tools accessible through a Python interface. Models can be loaded from Myokit's native file format or imported from CellML. Model export is provided to C, MATLAB, CellML, CUDA and OpenCL. Patch-clamp data can be imported and used to estimate model parameters. In this paper, we review existing tools to simulate the cardiac cellular action potential to find that current tools do not cater specifically to model development and that there is a gap between easy-to-use but limited software and powerful tools that require strong programming skills from their users. We then describe Myokit's capabilities, focusing on its model description language, simulation engines and import/export facilities in detail. Using three examples, we show how Myokit can be used for clinically relevant investigations, multi-model testing and parameter estimation in Markov models, all with minimal programming effort from the user. This way, Myokit bridges a gap between performance, versatility and user-friendliness. PMID:26721671
Wang, Weiling; Luo, Sen; Zhu, Miaoyong
2016-03-01
In the second part (Part II) of the present simulation work, the three-dimensional (3D) dendritic growth of Fe-0.82wtpctC alloy is investigated with the 3D CA-FVM cellular automaton-finite volume method model developed in Part I. The influences of the melt undercooling, the interfacial anisotropy, and the forced flow on the equiaxed dendritic growth, especially the formation of secondary arms, are discussed. The comparisons of equiaxed dendritic growth in 3D and two-dimensional (2D) are also carried out. Finally, the columnar dendritic growth under different cooling conditions is investigated including the morphology and the secondary dendrite arm spacing (SDAS). The results show that the high undercooling can promote the formation of secondary arms as the anisotropy parameter is 0.04. With the increase of the anisotropy parameter, the secondary arms first reduce and then well develop again; meanwhile the tertiary arms are gradually developed. However, the secondary arms vanish at the undercooling of 5 K as the anisotropy parameter increases to 0.04. With the introduction of the forced flow with the inlet velocity of 0.001 m/s along the x axis, the secondary arms at the left (upstream) arm become more developed. However, they become slightly less developed with the forced flow intensifying. Secondary arms at the left side (upstream) of the perpendicular arms and in the y-z symmetrical plane become more and more developed as the inlet velocity increases. The competition of the secondary arms at the right side (downstream) of the perpendicular arms and at the right (downstream) arm becomes significant as the undercooling increases from 10 to 15 K. The solute-enriched envelope in 2D is much thicker than in the 3D case, so that the dendritic growth in 2D is influenced more by the melt flow and the undercooling; moreover, the secondary arms in 2D are hard to form even at the undercooling of 15 K and with the forced convection in the present article. Meanwhile, the
恶劣天气环境下的交通流数值模拟%Numerical Simulation of Traffic Flow in Inclement Weather Condition
Institute of Scientific and Technical Information of China (English)
祝会兵
2014-01-01
Based on the NaSch model of traffic flow, a modified cellular automaton traffic model is proposed. The model is attempted to reflect the characteristics of discreetness found in vehicle drivers under rain or snow weather condition. In the modeling process, the special driving condition of wet, slippery road and poor visibility are taken into account. The fundamental diagrams of traffic flow are obtained based on the numerical simulation, in which different percentage of discreet drivers is sampled. It is found that the percentile value of discreet drivers has effect on the traffic flow. By presenting the spatial-temporal profiles, the nonlinear properties of traffic flow in the inclement weather condition are analyzed thoroughly. It can be noted that traffic jams occur more frequently in rainy or snowy weather. It is in agreement with the actual traffic characteristics, so the presented model can also partly describe the microscopic characteristics of traffic flow in the inclement environment. The results demonstrate that the driver behavior has significant effect on the occurrence of traffic congestion.%基于 NaSch 模型提出了一个改进的元胞自动机交通流模型，旨在反映雨雪天气时道路湿滑能见度差的情况下司机驾驶车辆更加谨慎的特点。考虑谨慎司机的不同比例，通过数值模拟得到了一组基本图，发现含有不同比例的谨慎司机对交通流产生不同程度的影响。并通过车辆的时空演化图，从微观的角度对恶劣天气时交通流的非线性特性进行了细致的分析，揭示了在雨雪等恶劣环境下更容易出现交通拥堵的机理，与实际交通特征相吻合。因此模型能够部分地反映恶劣天气时交通流的微观特性，同时也证明了司机的驾驶行为对交通拥堵的形成确实具有重要的影响。
Cellular phones: are they detrimental?
Salama, Osama E; Abou El Naga, Randa M
2004-01-01
The issue of possible health effects of cellular phones is very much alive in the public's mind where the rapid increase in the number of the users of cell phones in the last decade has increased the exposure of people to the electromagnetic fields (EMFs). Health consequences of long term use of mobile phones are not known in detail but available data indicates the development of non specific annoying symptoms on acute exposure to mobile phone radiations. In an attempt to determine the prevalence of such cell phones associated health manifestations and the factors affecting their occurrence, a cross sectional study was conducted in five randomly selected faculties of Alexandria University. Where, 300 individuals including teaching staff, students and literate employee were equally allocated and randomly selected among the five faculties. Data about mobile phone's users and their medical history, their pattern of mobile usage and the possible deleterious health manifestations associated with cellular phone use was collected. The results revealed 68% prevalence of mobile phone usage, nearly three quarters of them (72.5%) were complainers of the health manifestations. They suffered from headache (43%), earache (38.3%), sense of fatigue (31.6%), sleep disturbance (29.5%), concentration difficulty (28.5%) and face burning sensation (19.2%). Both univariate and multivariate analysis were consistent in their findings. Symptomatic users were found to have significantly higher frequency of calls/day, longer call duration and longer total duration of mobile phone usage/day than non symptomatic users. For headache both call duration and frequency of calls/day were the significant predicting factors for its occurrence (chi2 = 18.208, p = 0.0001). For earache, in addition to call duration, the longer period of owning the mobile phone were significant predictors (chi2 = 16.996, p = 0.0002). Sense of fatigue was significantly affected by both call duration and age of the user
Institute of Scientific and Technical Information of China (English)
董力耘; 陈立; 段晓茵
2015-01-01
It is of fundamental importance to investigate the evacuation process from a room with obstacles. The typical case is the evacuation of students from a classroom. Based on evacuation experiments from a classroom, the essential features of evacuee are concluded. In the original floor field model, the dynamic floor field is introduced in order to reflect the interaction among pedestrians. A pedestrian may follow the virtual trace of another one in front. The static floor field does not consider the influence of pedestrians. In this paper, the original dynamic floor field is ignored. These desks and chairs are treated as impassable and passable static obstacles, respectively. The static and passible obstacles, such as chairs, lead to the delay of movement of pedestrians. Furthermore, pedestrians are regarded as movable obstacles. The effect of static obstacles on floor field does not change with time. However, the effect of movable obstacles on floor field is dynamic. Therefore, the whole floor field is updated dynamically according to the movement of crowd. Pedestrians may try to find another uncongested path or exit when they find the crowd in front. It provides a better description of the influence of downstream congestions on upstream crowd. The cellular automaton model based on the dynamic floor field is used to investigate the evacuation process in the case of four layouts and three exit widths. The spatial distributions of evacuation time in different conditions and also the average and maximum evacuation times are obtained. Numerical simulations reproduce the evacuation process observed in the experiment quite well. The evacuation time depends on arrangement of these desks and the exit width. For a given layout, the smaller exit leads to longer evacuation time. It is found that the evacuation time does not decrease monotonically with increasing the number of aisles, which depends on the width of aisle as well. When the aisle is not wide enough, the conflict of
Radiation, nitric oxide and cellular death
International Nuclear Information System (INIS)
The mechanisms of radiation induced cellular death constitute an objective of research ever since the first biological effects of radiation were first observed. The explosion of information produced in the last 20 years calls for a careful analysis due to the apparent contradictory data related to the cellular system studied and the range of doses used. This review focuses on the role of the active oxygen species, in particular the nitric oxides, in its relevance as potential mediator of radiation induced cellular death
Autophagy and mitophagy in cellular damage control
Directory of Open Access Journals (Sweden)
Jianhua Zhang
2013-01-01
Full Text Available Autophagy and mitophagy are important cellular processes that are responsible for breaking down cellular contents, preserving energy and safeguarding against accumulation of damaged and aggregated biomolecules. This graphic review gives a broad summary of autophagy and discusses examples where autophagy is important in controlling protein degradation. In addition we highlight how autophagy and mitophagy are involved in the cellular responses to reactive species and mitochondrial dysfunction. The key signaling pathways for mitophagy are described in the context of bioenergetic dysfunction.
Optimized Cellular Core for Rotorcraft Project
National Aeronautics and Space Administration — Patz Materials and Technologies proposes to develop a unique structural cellular core material to improve mechanical performance, reduce platform weight and lower...