Cellular automaton model of crowd evacuation inspired by slime mould

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 biological laboratory experiments.     

On Incentives and Updating in Agent Based Models

This paper introduces the concept of incentive based asynchronous updating in which the order of updating is determined by incentives. Previously, asynchronous updating has been shown to yield greater stability than synchromous updating for a variety of dynamical systems. However, in those models the order of updating is random. When incentives determine the ordering, the dynamics and end states change. For a conformity model on a two dimensional cellular automata, incentive based asynchronous updating yields greater linear disparity. Fot the game of life, it results in much greater sensitivity to initial conditions.     

The effect of different motion types in simple discrete particle systems with quantitative stigmergy

Discrete particle systems with quantitative stigmergy (ant systems, and particle based simulations of slime mould) are relevant to computational biology and are used as an alternative means to approximate solutions of intractable optimisation problems. The current range of such particle systems exhibits complex behaviour, and particular systems are therefore studied mainly empirically. In contrast, less complex systems, such as cellular automata are better understood and are more amenable to mathematical analysis. To create a bridge between the well-understood area of cellular automata on the one hand and the less understood area of particle systems with quantitative stigmergy on the other hand, this paper proposes to study strongly simplified versions of such particle systems. Eight different motion types are described and evaluated with respect to global system behaviour. The results are analytical as well as empirical. One result is that simple discrete particle systems with quantitative stigmergy permit the derivation of analytical results such as the convergence to a dynamic equilibrium. Another result is that even extreme simplification leaves room for an extraordinary rich spectrum of different motion types, each with its own particular effect on global system behaviour such as particle flow an persistence of particle corridors.     

基于二维元胞自动机的双向触发并行加密模型*

根据二维触发元胞自动机的特性,提出了一种二维元胞自动机双触发并行加//解密模型。仿真实验表明:与一维耦合触发元胞自动机相比,二维元胞自动机双触发并行加密模型在适度减慢加/解密速度的情况下,大大提高了密钥空间,具有极高的时间换空间的效率,很好地提高了健壮性和实用性。     

一种基于博弈论的疏散出口选择模型

针对紧急情况下人员疏散行为的特点,提出一种基于博弈论的疏散模型。模型考虑了疏散过程中疏散者之间的相互影响,每个逃生者根据其他逃生者的策略进行最优决策,逃生者的策略为纳什均衡下的策略。给出纳什均衡的求解方法,通过实例模拟验证其合理性。模型采用基于元胞自动机的仿真技术对人员疏散过程进行仿真,通过仿真表明模型能有效模拟多出口条件下人员应急疏散特性。     

Cellular Automata Simulations of Traffic: A Model for the City of Geneva

This paper proposes a micro-simulation based on a simple cellular automata model to analyze and describe the traffic of cars in the city of Geneva. We consider a road network containing the most important roads in the city center and its suburbs. As many as 1066 street junctions are considered, for a total network length of about 4000 km. Our simulation reproduces the rush hour period, based on real data involving around 85000 vehicles. The main properties we study concern the average travel time and its fluctuation of various routes, as a function of the departure time. Finally we briefly discuss the computer implementation of our model and its performance on a parallel computer.     

基于微分博弈的无线传感器网络恶意程序传播模型

恶意程序传播是无线传感器网络WSNs(Wireless Sensor Networks)面临的一项重要安全问题,传统的研究大多从入侵检测方法的角度阻止恶意程序的传播,很少考虑攻防博弈策略对恶意程序传播过程的影响。从博弈论的角度对攻防双方的博弈策略进行分析,建立了WSNs的攻防博弈模型及恶意程序传播模型,并将博弈均衡策略与传播模型耦合起来,得到了博弈参数与传播模型的稳态感染比例之间的关系。研究结果显示:当合法节点被感染恶意程序时的损失大于其检测到恶意程序时的收益时,能有效抑制WSNs中恶意程序的传播。此外,通信半径的增加、节点的移动行为能加速恶意程序的传播。研究结果对抑制WSNs中的恶意程序传播具有理论指导作用。     

技术创新扩散的元胞自动机仿真

首先通过对Bass模型进行参数估计,建立了基于元胞自动机的技术创新扩散模型,然后基于仿真软件Agentsheets设计和实现了仿真,最后以中国互联网络技术扩散为对象进行了实证研究,并将CA模型、Bass模型和实际数据进行了对比分析,对未来的网民数扩散的趋势进行了预测。该元胞自动机模型将网民数扩散的过程直观展示出来,仿真结果符合实际情况。     

一种基于OpenGL的三维元胞自动机模型

本文以Visual C＋＋为编译平台,运用OpenGL图形函数库建立了一种三维元胞自动机模型。该模型具备了经典元胞自动机的基本特征,因此可以根据需要进行扩展。文中运用该模型进行了简化的枝晶生长模拟,并与二维的模拟结果进行比较,验证了该模型的正确性。     

Ergodic Quantum Computing

We propose a (theoretical) model for quantum computation where the result can be read out from the time average of the Hamiltonian dynamics of a 2-dimensional crystal on a cylinder.The Hamiltonian is a spatially local interaction among Wigner–Seitz cells containing six qubits. The quantum circuit that is simulated is specified by the initialization of program qubits. As in Margolus Hamiltonian cellular automaton (implementing classical circuits), a propagating wave in a clock register controls asynchronously the application of the gates. However, in our approach all required initializations are basis states. After a while the synchronizing wave is essentially spread around the whole crystal. The circuit is designed such that the result is available with probability about 1/4 despite of the completely undefined computation step. This model reduces quantum computing to preparing basis states for some qubits, waiting, and measuring in the computational basis. Even though it may be unlikely to find our specific Hamiltonian in real solids, it is possible that also more natural interactions allow ergodic quantum computing.PACS:03.67.Lx     

人工生命研究综述

详细综述了人工生命的产生、发展，回顾了有关人工生命科学的重要国际会议，着重介绍了人工生命研究的重要思想以及人工生命的研究领域，并阐述了人工生命的应用发展情况，特别在智能优化计算与仿真领域等的重要应用．人工生命的研究有助于揭示生命的本质，探索生命的起源，为生物学研究提供新的途径，具有重要的科学意义．     

人工生命

人工生命是一类具有生命特征，以自适应、自组织为主要特征的一类复杂系统，其研究成果可广泛用于生物学及计算机科学等许多工程领域。文中介绍了人工生命的产生背景、定义、研究内容、研究方法、理论基础、研究意义及与人工智能等相关学科的区别，以便全面深入地理解它。     

基于元胞自动机扩展模型的图的最短路径算法

利用元胞自动机在元胞空间上的并行特性,采用元胞动态邻居,时间段自适应调整的方法,构造出一种新的基于元胞自动机扩展模型的最短路径搜索算法,即通过简单规则的元胞状态演化,得到带权图的最短路径;该方法经过优化,能够达到Dijkstra算法的时间效率;并且为基于元胞自动机扩展模型解决图的问题的提供了新的思路。     

双目标推动下群体行为的元胞自动机模拟

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。     

基于元胞自动机的洪泽湖洪水蔓延模型研究

分析了元胞自动机的基本原理和构成,利用元胞自动机原理建立了洪泽湖洪水蔓延模型。模型以栅格空间数据结构作为基础,采用二维元胞自动机模型,确定了元胞空间和元胞状态,建立了洪泽湖洪水蔓延的规则,并根据规则以9邻域方式进行元胞状态的更新。选择性地测试了洪水蔓延模型的计算结果,模型计算数据与实际数据的比较表明,二维元胞自动机模型能够更为简单、快速地模拟洪泽湖洪水的蔓延。     

基于元胞自动机的网络舆论激励模型

为了研究网络舆论的传播过程及发展趋势,建立了一个基于元胞自动机的网络舆论激励模型,用于模拟网络舆论形成过程中个体发表言论数的变化以及个体观点的变化。在模型中,将网络空间的个体抽象为以情感描述的元胞,用情感倾向度和情感倾向度门限来确定元胞发表言论的状态,用情感激励来描述元胞的移动规则。同时,该模型考虑了个体数量增减和社会突发事件对网络舆论传播的影响,从而更能准确地模拟网络现实事件。     

基于GPU的元胞自动机熔岩流动模拟

为解决基于元胞自动机进行熔岩流动模拟的计算效率问题,提出一种应用在元胞自动机上的GPU并行计算方法。将元胞自动机中每一个方形网格映射到GPU的一个逻辑计算单元上,通过并行计算,提高模拟的效率,解决传统串行计算方法的不足,使模拟达到实时性。模拟结果表明,在元胞自动机的物理模型理论基础上,用GPU并行计算进行加速,在模拟效果和时间效率上均取得了良好的效果。