第二相颗粒对多晶材料晶粒生长影响的元胞自动机(CA)模拟

采用Moore型邻域定义的元胞自动机模型模拟研究第二相颗粒对多晶材料晶粒生长的影响.结果表明:第二相颗粒的体积分数及尺寸对基体晶粒组织特征的影响很大;第二相颗粒含量增加可以提高晶粒尺寸分布的均匀性,而颗粒尺寸增大则导致晶粒尺寸分布的均匀性降低.通过对模拟数据的回归分析获得极限晶粒尺寸(D)与颗粒尺寸(d)和颗粒含量(f)之间的关系;不同的颗粒尺寸(d)对应不同的拟合指数(n).     

基于时间自动机的Ad hoc网络入侵检测

该文提出一种基于时间自动机分布式合作的入侵检测算法。首先,将整个网络分为子区域,每一区域随机选出簇头担任监视节点,负责本区域的入侵检测。其次,按照路由协议构筑节点正常行为和入侵行为的时间自动机,监视节点收集其邻居节点的行为信息,利用时间自动机分析节点的行为,识别入侵者。该算法不需要事先进行数据训练并能够实时检测入侵行为。最后,通过模拟实验证实了算法的有效性。     

Cellular automaton modeling on the corrosion/oxidation mechanism of steel in liquid metal environment

Corrosion and oxidation of structure material in liquid lead alloys, which have been strongly associated with the nuclear industry, are specific but important areas of corrosion in liquid environments. In high temperature liquid metal environment, the corrosion rate of stainless steels is controlled by the solid diffusion of iron along grain boundaries in the oxide layer and a duplex oxide layer is formed with the inner layer growing by infiltration of corrosive solution along oxide micropores and the outer layer growing by the diffusion of metal ions. To interpret the role of diffusion and reaction process in the process of oxidation, a cellular automaton model, which combines the surface growth and internal oxidation, was created to explain the oxidation mechanism of steels in high temperature corrosive liquid metal environment. In this model, three main processes, which include the corrosion of the substrate, the diffusion of iron species across the oxide layer and precipitation of iron on the oxide layer, are simulated. The diffusion process is simulated by random walk model. Mapping between present model and experimental data has been created. The gross features concerning the evolution of the involved process were explored.     

Computing with random quantum dot repulsion

Quantum dot cellular automata (QCA) show great promise for fast computation with larger integration density and lower power consumption. Unfortunately, previous research has shown that QCA are likely to be extremely sensitive to placement error. During an investigation into placement sensitivity, it was discovered that completely random quantum dot structures have the ability to compute simple binary functions. In this paper, we further explore the random structures in an idealized way, looking for higher-order functions; an example of one-bit full adder is shown in the paper. Moreover, a new structure, the semi-random structure, is introduced to alleviate some, but not all, difficulties in connecting disparate random structures; the difficulties arise from the fact that inputs and outputs to and from a purely random structure may not reside at the edges of the structure. In the semi-random structure, the inputs and outputs are localized to the edges. It is demonstrated that semi-random structures, like random structures, can almost assuredly compute simple Boolean functions.     

Moore Automata for the Supervisory Control of Robotic Manufacturing Workcells

The potential of flexible-manufacturing workcells (FMCs) to produce a family of parts in many possible orders of operations and choices of different machines is advantageous. Despite intensive research on the theoretical control of discrete-event systems (DESs), however, current techniques can still only be used for the supervisory control of simple cells. In this paper, a novel modeling and control synthesis technique is presented for FMCs that allow part-routing flexibility. Our proposed methodology combines Extended Moore Automata (EMA) and Controlled-Automata theories to synthesize supervisors for such FMCs.     

声格固体模型地震波场模拟

ＰｅｔｅｒＭｏｒａ为模拟复杂介质中的纵波，提出了声格固体模型，即在格子Ｂｏｌｔｚｍａｎ模型基础上引入变速粒子而建立的细胞自动机模型，从而为利用这种方法模拟地震波场奠定了理论基础。文中简要介绍了Ｐｅｔｅｒ Ｍｏｒａ的声格固体模型的基本理论框架及差分算法，同时还介绿了黄联捷的插值算法。     

Diagnosis of Active Systems by Automata-Based Reasoning Techniques

This paper presents a method for the diagnosis of active systems, these being a class of distributed asynchronous discrete-event systems, such as digital networks, communication networks, and power transmission protection systems. Formally, an active system is viewed as a network of communicating automata, where each automaton describes the behavior of a system component. The diagnostic method encompasses four steps, namely system modeling, reconstruction planning, behavior reconstruction, and diagnosis generation. System modeling formally defines the structure and behavior of system components, as well as the topology of the active system. Based on optimization criteria, reconstruction planning breaks down the problem of system behavior reconstruction into a hierarchical decomposition. Behavior reconstruction yields an intensional representation of all the dynamic behaviors that are consistent with the available system observation. Eventually, diagnosis generation extracts diagnostic information from the reconstructed behaviors. The diagnostic method is applied to a case study in the power transmission network domain. Unlike other proposals, our approach both deals with asynchronous events and does not require any global diagnoser to be built off-line. The method, which is substantiated by an ongoing implementation, is scalable, incremental, and amenable to parallelism, so that real size problems can be handled.     

Numerical simulation of typical contact situations of brake friction materials

In the paper, a model typical for contact situations of automotive brakes is established based on the method of movable cellular automata. The processes taking place at local contacts in an automotive brake system are analysed. Based on microscopic and micro-analytical observations, the following contact situations were simulated: (i) a couple of ferritic steel against pearlitic steel, both covered by an oxide layer mixed with graphite nanoparticles and (ii) the same situation but without oxide layers. The results of calculated mean coefficients of friction of the oxide-on-oxide contact correspond well to expected values for a real braking system, whereas steel-on-steel contact are twice as high. This allows one to make some conclusions; for example, oxide formation will take place more quickly than friction layer elimination, and finally this is responsible for the stabilisation of the coefficient of friction.     

Pixelated structures as a compositional medium

This paper illustrates the use of pixelated structures as a compositional medium. In this medium, compositions are constructed from parts that are very simple. Methods to generate a design vocabulary from these parts, and establish relationships between parts to construct compositions are brought together in the framework of formal languages. Finally, examples of compositions developed in this medium are presented.     

环上线性有限自动机的可逆性的一些结果

本文证明了有单位元的有限交换环R上任何延迟t步(弱)可逆线性有限自动机皆有延迟t步线性(弱)逆的充分必要条件是环R满足条件: x(Ax=0→bx=0)→y(b=yA)我们还证明了对任何有单有限交换环R,R上输入、输出维数相同的延迟t步(弱)可逆线性有限自动机具有延迟t步线性(弱)逆.