在常规错误下具有一个储备部件的冗余系统的稳定性分析

以在常规错误下具有一个储备部件的冗余系统为例,利用半群理论对系统算子的谱点分布进行分析,根据算子半群的稳定性原理,得出了该系统解的渐进稳定性的证明.     

趋旋性微生物在幂律流体饱和水平多孔层中的热-生物对流稳定性分析

基于趋旋性微生物和幂律流体模型,研究了在含有非Newton流体饱和多孔介质中生物对流的线性稳定性问题.利用Galerkin数值方法求解了该系统的控制方程,得到生物Rayleigh数的数值解,讨论了非Newton流体的幂律指数对生物对流稳定性在假塑性流体和膨胀性流体间的变化规律.研究结果表明,随着幂律流体的速度增大,幂律指数对生物对流稳定性的影响会发生变化,并且这种变化会受到热Rayleigh数和生物Lewis数的影响.另外,微生物趋旋性特征越明显,生物对流系统就越不稳定,而适当增大非Newton流体的幂律指数则有利于系统的稳定性.     

模糊仿生间接自适应控制用于逼近误差的估计

针对一类不确定非线性系统,提出将生物个体对外界环境的适应对策引入到间接模糊自适应控制方法.方法的特点是将生物个体的主动自适应性与模糊控制相结合,将反应生物特性能力的结构单位生态位作为模糊规则后件.在仿生模糊系统的基础上,利用Lyapunov综合方法形成状态反馈仿生自适应控制算法,关键问题是重构误差有界,得到的系统具有良好逼近性.仿生控制律有两部分构成,一部分是等效控制,另一部分是边界控制,边界参数自适应律被用于这个边界控制,根据稳定性理论,证明闭环系统的全局稳定性.最后对倒立摆系统进行了仿真,结果证明了该方法的有效性和可行性.     

常规故障具预警功能的两相同部件并联冗余可修复系统

研究了常规故障具预警功能的两相同部件并联冗余可修复系统.通过选取状态空间和定义系统算子,将模型方程转化成为了抽象Cauchy问题.然后利用算子半群理论证明了系统解的存在唯一性与指数稳定性.另外,得到结论:当风险系数λc趋于无穷大时,这种系统逼近于一种具有mild解的模型系统.     

基于烟花进化人工鱼群算法和多重分形的属性选择方法在空气质量预测中应用

日益严重的空气污染,严重影响日常生产生活.因此,亟需对空气质量进行预测.为了实现高效、科学的预测,需准确地选择出空气质量数据集中的关键影响因素,故提出了基于烟花进化人工鱼群算法和多重分形的属性选择方法,并应用于空气质量预测中.首先,采用混沌初始化方式生成初始种群,对人工鱼群算法进行离散化改进,并引入烟花进化机制,提出烟花进化人工鱼群算法(FEAFSA),提高算法的搜索效率;其次,融合FEAFSA和多重分形维数(MFD),对空气质量数据集进行属性选择,约简冗余、不相关属性,保留空气质量关键属性;最后,在8个UCI数据集上的实验结果表明,相较于其他属性选择方法,其能有效剔除冗余因素,性能更优,同时表明其有效性、稳定性和显著性.在进行性能测试之后,将其应用于北京、上海和广州地区的空气质量等级和指数预测中,取得了良好的预测效果.     

复杂生态系统的模糊数学模型

生态系统是一个复杂的大系统，很多重要的生态学理论问题都是以生态位(niche)和生物群落概念为基础的。本文将生态位和群落抽象出来，看作是一个耗散结构。建立生态系统中基本概念的量化算子，利用系统模糊分析理论给出具有明确生物意义的生态位和群落的Fuzzy数学模型。并以此讨论生态系统中其他相关概念的数学模型、群落的水平和垂直格局及物种间在资源、斑块、时间三维模糊集上的互惠，共处和竞争关系。初步构建起复杂生态大系统的数学理论框架。     

两比例失效率元件组成串联系统元件冗余与系统冗余的随机比较

针对两个比例失效率元件组成的串联系统,在热冗余的情形下,讨论了串联系统的元件冗余与系统冗余两种方案,并基于随机序的方法,对普通随机序、失效率序、反失效率序建立了元件冗余优于系统冗余的随机比较理论.     

具有生态位构建作用的种群进化动力学模型及其应用研究

依据进化动力学的理论与方法,系统探讨了生态位构建的机理与模式．通过建立生态位构建的空间模式及其适合度计算公式和具有生态位构建作用的单种群与两种群的进化动力学模型,并对其种群进化动态、种间竞争共存机制进行的理论与数值模拟分析,揭示了生物与环境资源的协同进化关系．结果表明:种群动态受其主要生态因子及资源含量的正反馈作用．生态位构建作用通过对种群适宜度的影响而产生进化响应．单种群动力系统存在种群大小的阈值效应;在两竞争种群动力系统中,生态位构建可以导致进化动力系统的多个竞争结果,从而为解释种间竞争与稳定共存提供了一种新的理论机制．     

金融机构的稳定性

用系统的观点分析金融稳定性问题,先简介了金融系统的有关概念,比较了金融稳定性和生态学稳定性概念以及金融生态环境与金融系统稳定性的关系,讨论了与金融稳定性有关的问题,论证了金融机构确定模型和随机模型以及具有下临界点L的金融机构模型的稳定性,构建并论述了金融群落、金融群落层级结构系统的稳定性.     

具有内部构造安全保障体系的冗余机器系统的稳定性及可靠性分析

对具有内部构造安全保障体系的冗余机器系统的渐近稳定性先进行了证明.再对系统解的可靠性作了初步的研究证明.即瞬态可靠性大于等于其牢固可靠性。     

基于改进DEA——以复相关系数为基准的滞后期的我国产业结构演化效率评价

为了评价我国的产业结构演化效率,本文构建了我国产业结构演化评价指标体系。针对传统DEA方法的局限性,文中引入以复相关系数为基准的滞后期,解决了产业结构演化评价中投入和产出之间的滞后性问题,建立更加有效的DEA改进模型,对我国产业结构演化效率进行评价。结论表明,各产业技术效率大部分时间大于规模效率,而且投入要素出现不同程度的冗余情况,近年来,第一、二产业固定资产投资和就业人员冗余程度有减轻的趋势,第二产业能源和水资源消耗较大,同时第三产业各要素冗余程度均有所加深。针对这一现象,本文提出了相关对策建议。     

Optimal sensor placement for spatial lattice structure based on three-dimensional redundancy elimination model

Spatial lattice structures are widely applied in engineering fields attributed to their superiorities in weight and reasonable stress. It is essential to select the best sensor placement layout for structural health monitoring and safety purposes, yet it is neither realistic nor efficient to place sensors in every location possible on the structure. To meet the strong requirements for optimal sensor placement in spatial lattice structure, this paper aims to investigate a combined objective function based on effective independence method and three dimensional redundancy elimination model to balance between optimal sensor placement performance and elimination in redundancy. To eliminate redundant information and resource waste caused by the clustered sensor distribution, the three-dimensional redundancy elimination model is constructed with the consideration of nearer nodes and overall sensor distribution ranges in three-dimensional cases. In addition, the combined function is constructed by giving the two component functions equal significance using weighting factors and normalization, and solved by genetic algorithm. Finally, the proposed method for spatial lattice structure is supported by three numerical examples including a simple lattice structure, a ground spatial truss structure and a space docking modular in space solar power satellite.     

Minimal covering problem and redundancy reduction in databases

One of the main problems in efficient organization of a database system is minimization of the redundancy of information. In this paper, we enumerate the causes of redundancy and reduce the problem of redundancy minimization to the minimum covering problem. This requires inclusion in the database management system of a module for aggregation of data elements into larger constructs — segments, records, files. The module can be software or hardware implemented. Regardless of its implementation, the module has the structure of a 0–1 matrix, which can be transformed by the standard methods of block matrices. A compression algorithm is proposed, which reduces the redundancy introduced by the designer or by the users in single and multiuser queries.Translated from Vychislitel'naya i Prikladnaya Matematika, No. 64, pp. 141–144, 1988.     

Organizational implications of systems thinking: Multidimensional modular design

Despite a well recognized systemic principle that parts of an organization are interdependent and the nature of their interaction defines the behavior of the whole, we have stubbornly held to the illusion that each function is more or less self-contained and can be treated independently. For a majority of managers the unidimensional mode of organization based on structurally defined tasks, segmentation and hierarchical coordination of functions seems to be the only acceptable way of organizing the work. A predominant management culture continues to value narrow specialization very dearly and considers any forms of redundancy in the organizational structure as wasteful and inefficient. However, the ability to adapt requires some forms of flexibility and responsiveness, which in turn demands that some degree of redundancy be built into the system.The required level of interaction and flexibility in an organization can be achieved by creating a modular structure embedded in a multidimensional scheme. The resulting mode of organization is capable of redesigning its structure and redefining its functions, so that it can exhibit different behaviors and produce different outcomes in the same or different environments.     

Redundancy of Fusion Frames in Hilbert Spaces

Upon improving and extending the concept of redundancy of frames, we introduce the notion of redundancy of fusion frames, which is concerned with the properties of lower and upper redundancies. These properties are achieved by considering the minimum and maximum values of the redundancy function which is defined from the unit sphere of the Hilbert space into the positive real numbers. In addition, we study the relationship between redundancy of frames (fusion frames) and dual frames (dual fusion frames). Moreover, we indicate some results about excess of fusion frames. We state the relationship between redundancy of local frames and fusion frames in a particular case. Furthermore, some examples are also given.     

On redundancy in multi criteria decision making

The concept of redundancy is accepted in Operations Research and Information Theory. In Linear Programming, a constraint is said to be redundant if the feasible decision space is identical with or without the constraint. In Information Theory, redundancy is used as a measure of the stability against noise in transmission. Analogies with Multi Criteria Decision Making (MCDM) are indicated and it is argued that the redundancy concept should be used as a regular feature in conditioning and analysis of Multi Criteria Programs. Properties of a proposed conflict-based characterisation are stated and some existence results are derived. Redundancy is here intended for interactive methods, when the efficient set is progressively explored. A new redundancy test for the linear case is formulated from the framework. A probabilistic method based on correlation is proposed and tested for the non-linear case. Finally, some general guidelines are given concerning the redundancy problem.     

Interpretation of redundancy analysis: Rotated vs. unrotated solutions

Some properties of redundancy analysis are summarized and suggestions for normalization are given. The relations between redundancy analysis and principal component analysis and, to a lesser extent, canonical analysis, are reasons for considering rotation techniques on the primary solution. An example from practice is given in which redundancy analysis is a useful technique, but where rotation of its results is desired in order to simplify the interpretation.     

A quantitative notion of redundancy for finite frames

The objective of this paper is to improve the customary definition of redundancy by providing quantitative measures in its place, which we coin upper and lower redundancies, that match better with an intuitive understanding of redundancy for finite frames in a Hilbert space. This motivates a carefully chosen list of desired properties for upper and lower redundancies. The means to achieve these properties is to consider the maximum and minimum of a redundancy function, which is interesting in itself. The redundancy function is defined on the sphere of the Hilbert space and measures the concentration of frame vectors around each point. A complete characterization of functions on the sphere which coincide with a redundancy function for some frame is given. The upper and lower redundancies obtained from this function are then shown to satisfy all of the intuitively desirable properties. In addition, the range of values they assume is characterized.     

Symmetry in complex networks

We consider the size and structure of the automorphism groups of a variety of empirical ‘real-world’ networks and find that, in contrast to classical random graph models, many real-world networks are richly symmetric. We construct a practical network automorphism group decomposition, relate automorphism group structure to network topology and discuss generic forms of symmetry and their origin in real-world networks. We also comment on how symmetry can affect network redundancy and robustness.     

A note on the reliability of redundant systems

This paper attempts to study the effect of the order of redundancy of a system on its instantaneous failure rate, and its life expectancy. Closed form solutions are presented for types of systems which are commonly met with in engineering practice. Both subsystem redundancy and component redundancy are investigated and the latter is shown to be, in general, superior.