具有毒素和捕获作用的两种群竞争系统的稳定性分析

研究一类两种群无差别捕获的具有毒素作用的竞争系统.首先得到了系统存在唯一正平衡点的充分性条件;其次,通过构造适当的Lyapunov函数得到了保证该系统边界平衡点全局稳定的充分性条件;最后,在前人的基础之上得到了系统正平衡点全局渐近稳定的充分性条件,所得结果补充和完善了T.K.Kar和K.S.Chaudhuri的相应结果.     

非自治的具有阶段结构和时滞的捕食系统的动力学行为

本文研究了一个非自治的具有阶段结构和时滞的捕食-食饵模型.利用比较原理获得了系统持久性的条件,在假设系统为周期系统的条件下通过构造Liapunov函数证明了正周期解的存在唯一性和全局渐近稳定性.     

基于条件失效率的串和并联系统的失效率刻画

由于条件失效率有很好的直观意义且易获得,用它们去刻画相关部件组成的串或并联的系统失效率是一条有效的新途径.但并联系统失效率的表示过于复杂.由此,新定义过程失效率向量,但仍基于条件失效率,从另一方面描述并联系统的整个失效状况,并用Basu定义二维失效率说明其应用.最后,将以上两种刻画方式统一为系统过程失效率函数.     

具脉冲和时滞影响的非线性抛物系统边值问题的振动结果

研究一类具非线性扩散项的脉冲时滞抛物偏微分系统解的振动性,借助Green公式、垂直相加法和脉冲时滞微分不等式,获得了该类系统在Robin边值条件下振动的充分性条件.所得结果充分反映了脉冲和时滞在系统振动中的影响作用.     

准对称流的混沌和共振流线

采用计算Melnikov函数的方法 ,研究了描述qth(q=3或 6 )准对称流流体粒子运动的动力系统 .文中在分析未扰动系统轨道解析表示的基础上 ,深入考察了扰动系统的分岔情况 .结果表明 ,扰动系统在一定条件下能够分支出混沌和共振流线 .     

具有扩散和时滞的捕食系统的持续生存

本文研究具有一般功能性反应和时滞的周期捕食系统的持续生存和周期解,得到了系统永久持续生存的充要条件.在此条件下系统存在正的ω周期解,改进了一些已知结果.     

连续时间系统的随机能观测性和缺初值估计

本文对连续时间线性随机系统给出了判别随机能观测的充分必要条件.如果系统退化为确定性系统,这个条件就成为判别系统完全能观测的条件.当系统随机能观测时,本文还讨论了未知初值统计特性时的状态和初值的估计问题。     

具有投放率和时滞的非自治扩散捕食-食饵模型的持久性和周期解

研究了一类具有投放率和时滞的具Beddington-DeAngelis类功能反应的非自治扩散捕食-食饵系统.证明了此系统在一定条件下是持久的,得到了系统存在唯一的全局渐近稳定的正周期解的充分条件.     

带有非线性收获和妊娠时滞的微分代数捕食者-食饵系统的稳定性及Hopf分支

本文研究了一类同时带有非线性食饵收获和捕食者妊娠时滞的微分代数捕食者-食饵系统的稳定性及Hopf分支问题.利用了分支理论和稳定性理论,以捕食者妊娠时滞作为系统的分支参数,获得了所提出的新系统在正平衡点处系统稳定性的相关判据条件和Hopf分支的产生条件.推广了一般带有线性收获和时滞的微分代数捕食者-食饵系统的结论.     

关于磁导率和介电常数重构的唯一性

本论文考虑Helmholtz系统下分片常数性质的磁导率和介电常数的重构.首先,我们将卡尔德隆等式推广到Helmholtz系统下,然后通过对一次测量数据限制适当的条件,可以证明重构具有唯一性.这在现有文献中是全新的.     

具有临界和非临界人为故障的人-机系统解的存在唯一性及半离散化

研究了具有临界和非临界人为故障率,且修复时间任意分布的可修复的人-机系统模型.利用初等方法将系统转换为8维Banach空间下的Volterra积分方程,得到系统非负解存在且唯一.并讨论了系统解的逼近.     

Unwanted noise and vibration control using finite element analysis and artificial intelligence

A mechatronic approach integrating both passive and active controllers is presented in this study to deal with unwanted noise and vibration produced in an automobile wiper system operation. Wiper system is a flexible structure with high order, nonlinear model that is considered as a multi objective control problem since there is a conflict between its functionality quality in wiping and generated unwanted noise and vibration. A passive control technique using multi body system (MBS) model and finite element analysis (FEA) is introduced to identify the potential of the effectiveness of the physical parameters of wiper blade to give appropriate range to reduce the unwanted noise and vibration in the system. While, the significant contribution of active controller is to deal with uncertainties exerted to system within wiper operation. In passive control stage, natural frequencies of a uni-blade automobile wiper are determined using modal testing. Later, a 3-dimensional model of a wiper blade assembly is developed in multi body system design to investigate the good validation test and agreement of the physical behavior of the system in experiment with finite element analysis. Parametric modification via complex eigenvalue is adopted to predict instability of the wiper blade. In active control level, experimental data collected from the wiper system during its operation. A system identification model named nonlinear auto regressive exogenous Elman neural network (NARXENN) is developed for implying the active controller. A bi-level adaptive-fuzzy controller is brought in whose parameters are tuned simultaneously by a multi objective genetic algorithm (MOGA) to deal with the conflict interests in wiper control problem.     

Strategic defense and attack for series and parallel reliability systems

A system of independent components is defended by a strategic defender and attacked by a strategic attacker. The reliability of each component depends on how strongly it is defended and attacked, and on the intensity of the contest. In a series system, the attacker benefits from a substitution effect since attacker benefits flow from attacking any of the components, while the defender needs to defend all components. Even for a series system, when the attacker is sufficiently disadvantaged with high attack inefficiencies, and the intensity of the contest is sufficiently high, the defender earns maximum utility and the attacker earns zero utility. The results for the defender (attacker) in a parallel system are equivalent to the results for the attacker (defender) in a series system. Hence, the defender benefits from the substitution effect in parallel systems. With budget constraints the ratio of the investments for each component, and the contest success function for each component, are the same as without budget constraints when replacing the system values for the defender and attacker with their respective budget constraints.     

Central limit theorem and chaoticity

This paper studies the relations between stochastic properties and chaotic properties of a dynamical system satisfying the central limit theorem. For such a system, it is proved that every nonempty open set in its defining space contains a point with positive lower density of its return time set and that the system is syndetically sensitive, provided that it is strongly topologically ergodic. Moreover, it is shown that the system admits many chaotic properties if its domain is restricted to a tree.     

具有多重严重故障和非严重故障和修复功能的系统的可靠性分析

该文研究一个具有多重严重故障和非严重故障和修复功能的系统的可靠性问题. 在泛函分析理论的框架下,将系统方程组写成一个 Banach 空间中的抽象初值问题,利用算子半群方法,研究了该系统的适定性、稳态解的存在性以及稳定性.表明: 在系统模型的假定下,所研究的系统是适定的,存在非负动态解和稳态解, 特别在范数意义下动态解收敛到稳态解.从而由系统稳态解得到的系统指标是可靠的.     

A Random Shock Model with Mixed Effect,Including Competing Soft and Sudden Failures,and Dependence

A system is considered, which is subject to external and possibly fatal shocks, with dependence between the fatality of a shock and the system age. Apart from these shocks, the system suffers from competing soft and sudden failures, where soft failures refer to the reaching of a given threshold for the degradation level, and sudden failures to accidental failures, characterized by a failure rate. A non-fatal shock increases both degradation level and failure rate of a random amount, with possible dependence between the two increments. The system reliability is calculated by four different methods. Conditions under which the system lifetime is New Better than Used are proposed. The influence of various parameters of the shocks environment on the system lifetime is studied.     

一个新混沌系统及错位投影同步通讯方案

提出了一个新的混沌系统,该系统含有五个参数,每个状态方程均含有非线性乘积项.通过理论推导,数值仿真,Lyapunov指数、Lyapunov维数、分岔图研究其基本的动力学特性,并分析了改变参数时系统的动力学行为的变化.本文研究了该系统的错位投影同步,设计了非线性控制器,实现了两个初值不同的新系统的错位投影同步.另外,将该系统及错位投影同步方法应用到保密通信中,基于改进的混沌掩盖通讯原理,在发送端使用新系统信号对信息信号进行加密及传送,最后在同步后的接收端不失真地恢复出有用信号.数值仿真表明所设计的新的混沌系统具有复杂的动力学特性,适用于保密通讯.     

矩阵系统的稳定与条件稳定

一个矩阵对应一种状态变换 .一系列的矩阵构成矩阵序列系统 .任一微小的扰动都会破坏伪逆的精确性 ,即状态的最后结果 .本文证明 :若矩阵系统是广义各态历经的 ,则系统是稳定的 ;若矩阵系统是普真的 ,则系统是条件稳定的 .     

Proofs and surfaces

A formal sequent system dealing with Menelaus' configurations is introduced in this paper. The axiomatic sequents of the system stem from 2-cycles of Δ-complexes. The Euclidean and projective interpretations of the sequents are defined and a soundness result is proved. This system is decidable and its provable sequents deliver incidence results. A cyclic operad structure tied to this system is presented by generators and relations.     

Analysis of the reliability and the maintenance cost for finite life cycle systems subject to degradation and shocks

This paper deals with a deteriorating system subject to two different causes of failure: internal continuous degradation and sudden shocks. The degradation process is modelled using a gamma process. It is assumed that the system fails when the deterioration level reaches a critical threshold. Furthermore, sudden shocks arrive at the system at random times following a non-homogeneous Poisson process. When a sudden shock takes place, the system fails. To control the system reliability, a condition-based maintenance is applied. Under this maintenance policy, availability measures of the system are obtained. It is shown that these measures fulfil Markov renewal equations. A recursive method is developed to compute these measures. Furthermore, the maintenance cost of this system is analysed. Traditionally, the maintenance cost is analysed assuming an infinite time span. However, most systems have a finite life cycle and the application of the asymptotic approach is questionable. In this paper, the maintenance cost is analysed considering a finite life cycle. A recursive method, which combines numerical integration and Monte Carlo simulation, is developed to obtain the expected cost rate in the finite life cycle and its associated standard deviation.