细胞自动机及其理论研究进展

细胞自动机固有的组成单元的简单性,单元之间作用的局部性和信息处理的高度并行性,并表现出复杂的全局特性等特点使得其广泛应用于物理模型模拟、密码学和内建式自测试等领域。本文简述了细胞自动机的基本概念,研究了细胞自动机的分析理论和细胞自动机的综合理论。     

元胞自动机预测客户群问题的研究

客户资产是企业的核心资产,能否拥有稳定的、高利润的客户群是企业能否获得竞争优势的关键所在,预测客户群就顺理成章地成为企业生存发展的必要战略.文章采用了元胞自动机模型,分析企业中的最佳客户群,为企业赢得最大的利润.     

基于元胞自动机的自旋玻璃离散优化

对无序复杂系统的研究,自旋玻璃一直是科学界最具成功的尝试之一。在对复杂事物的认知上,认为真正的复杂性问题只可能以复杂资源进行趋近。基于自旋玻璃的离散特性,首先论证了可以采用元胞自动机来研究自旋玻璃问题;进一步,通过在对一组铁磁与反铁磁材料的实验中,证实了用元胞自动机来解决自旋玻璃问题的可行性;在与模拟退火算法的比较研究中,表明用元胞自动机这一复杂资源探求自旋玻璃问题更具优越性。     

单元化制造的构造单元研究

研究了单元化制造的单元构造算法,提出了基于ｐ－ｍｅｄｉａｎ算法的具有多条工艺路线约束的优化改进算法;并将Ｃｈｏｏｂｉｎｅｈ算法改造为线性规划算法,降低原算法的求解难度。虽然单元构造的算法多种多样,但大都局限于某些个别指标的优化上,将改进的Ｐ－ｍｅｄｉａｊｎ和Ｃｈｏｏｂｉｎｅｈ算法综合为一个实用的单元构造聚类算法,以此设计的仿真系统适合于快速单元重构的需要,其评价指标对构建单元具有重要的指导意义。     

CDPD系统中逻辑链路控制的研究和实现

蜂窝数字分组数据（ＣＤＰＤ）系统是基于模拟蜂窝电话网的无线分组数据通信系统。针对无线信道的不稳定因素,研究了ＣＤＰＤ系统中的逻辑链路控制协议方案,并以面向对象的思想为基础介绍了该协议在ＵＮＩＸ操作系统上的开发。通过大量的现场实验,验证了该协议在无线信道条件下的有效性     

基于元胞自动机的创新扩散模型综述

元胞自动机（CA）是一种微观仿真模型，通过在微观层面上模拟个体行为和属性，自底向上地构建模型．更符合创新采纳的真实过程．是研究创新扩散的一种重要方法，CA模型应用于创新扩散已有十多年的时间．但至今仍然缺乏一个统一的研究体系．尚未见有相关的总结性文章发表。本文对这些模型进行综述性研究．旨在找出其中的内在联系．给出一个该领域的研究分析框架。首先从介绍CA入手，用一个具体的扩散模型说明了CA各要素的定义；接下来借鉴Mahaian对数学模型的分类方法将CA模型分为基本模型和扩展模型，并分别对这两类模型进行综述性研究；最后对当前研究的优势和不足分别进行了讨论。     

具分布时滞细胞神经网络全局渐近同步

探讨了一类具分布时滞的细胞神经网络的全局渐近同步问题,通过构造合适的Lyapunov-Krasovskii泛函,利用不等式理论,给出了驱动系统与响应系统全局渐近同步的几个充分条件.数值例子证明了所得结论的有效性.     

Effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material: A microstructure-based crystal plasticity finite element analysis

In this paper, the effects of subgrain size and static recrystallization on the mechanical performance of polycrystalline material were investigated using a microstructure-based crystal plasticity finite element(CPFE) model. Firstly, polycrystalline microstructures with different mean subgrain sizes were prepared using simple assumption based on experimental observations, and intermediate microstructures during static recrystallization(SRX) were simulated by a cellular automata model adopting curvature driven grain/subgrain growth mechanism. Then, CPFE method was applied to perform stress analysis of plane strain tension on these virtual microstructures. The results show that the subgrains inside pre-existing grains have an effect on the heterogeneity of the stress distributions. The average stress decreases with increasing the mean subgrain radius. As grain/subgrain grows during SRX, the average stress also decreases. It can be deduced that well-defined and finer subgrain structure may strengthen the polycrystalline material, while grain/subgrain growth during SRX process will degrade the strength.     

Development of in vitro toxicity tests with cultures of freshly isolated rat hepatocytes

Summary Freshly isolated and cultured hepatocytes were analyzed by two-parameter flow cytometry. The combined analysis of DNA and cellular protein content allowed the contribution of ploidy classes and of subpopulations within a ploidy class to be defined. Analysis of hepatocytes during exposure to dimethylsulfoxide (DMSO), phenobarbital (PB), low oxygen tension (5% O₂) or fetal calf serum (FCS), provided insight into the dynamic response of individual ploidy classes as a function of culture time. By analogy with the age-dependent ploidy shifts in vivo, hepatocyte-cultures shift towards adult animals during exposure to DMSO and towards young animals when cultured at low pO₂ (4% O₂). FCS and phenobarbital disturb this constitutive ploidy balance. FCS increased the 2 N cell population, where stem cells probably respond to the proliferative stimuli provided by growth factors in the serum. Phenobarbital affects the liver-specific 4 N hepatocytes, which agrees with effects seen in liver after exposure in vivo. It is suggested that drug-induced pathological alterations in ploidy in hepatocyte cultures could serve as indicators of compounds, such as liver tumor promoters, which interfere with cell differentiation in liver. The heterotypic cell-cell interaction of freshly isolated hepatocytes with isolated, in vitro cultured, rat liver epithelial cells in co-cultures proved to be a valuable concept in toxicity testing: aldrin epoxidase, an enzyme system involved in xenobiotic metabolism, was stabilized for more than two weeks. After exposure to the three chemicals, 2-acetylaminofluoren, procarbazine and cyproterone-acetate, a preferential toxicity for each compound and cell population was established. Thus heterotypic cell cultures can considerably increase the amount of information available from in vitro studies.The final concept, combining monitoring of cellular DNA (ploidy) and protein content in hepatocyte cultures during and after exposure to a given test compound at tissue oxygen tension with the heterotypic cell-cell interaction, would create a more in vivo-like culture system. This would enhance the predictability of hepatocyte cultures and contribute to a more widespread use of the test system and as a result help to reduce the number of whole-animal tests.     

钙及钙调素研究进展(Ⅰ)

解决细胞识别、细胞通讯、细胞代谢的调控、细胞增殖与细胞周期、细胞与抗病以及细胞对外界信号进行的持续反应维持等重大理论与实际问题。文中着重介绍了作为胞内信使的钙离子及其循环的重要意义、作为Ca~(2+)受体的胞内蛋白CaM的广泛性。作者认为CaM在细胞代谢调控中处于中心位置,对Ca~(2+)及其循环、第二信使系统CAMP和肌醇磷脂,甚致CGMP均有调节、协调作用;是调控细胞代谢的综合剂。