基于阈值判决的无线传感器网络混沌信号重构

考虑在传感器网络中重构混沌信号的问题.各传感器同时观测一个混沌信号.由于带宽受限,各传感器量化观测信号并将量化后的数据发送到融合中心,该中心使用无先导卡尔曼滤波算法重构观测的混沌信号.为了节省能量,只有观测信号信噪比高于某个阈值的传感器被选中并发送数据.定义代价函数关联重构性能和能量消耗,分析并仿真了代价函数和阈值之间的关系.结果表明在某些情况下部分传感器发送数据更合理.

Abstract：

The problem of reconstructing chaotic signals in wireless sensor networks is considered.All sensors observe a common chaotic signal.Because of the limited bandwidth,the observations are quantized and the quantized data are sent to a fusion center.The fusion center reconstructs the chaotic signals by using the unscented Kalman filtering(UKF)algorithm.To save energy,only the sensors for which the SNR of the observation is higher than a threshold are chosen for transmission.A cost function is defined to relate the reconstruction performance and the energy consumption.The relationship between the cost function and the threshold is analyzed and simulated.The results show that under certain conditions,it is more reasonable that only a portion of the sensors transmit data.     

正则Markov链的收敛与逼近

研究Markov链中概率转移函数的收敛性,用算子半群的方法证明了正则概率转移函数的收敛与其对应的预解函数的收敛等价,并给出了概率转移函数收敛的q-矩阵条件.

Abstract：

This paper discusses the convergence and approximation in Markov chains by employing operator semigroup method.It is showed that if the Markov chains are regular,then the convergence of a sequence of transition functions is equivalent to the convergence of the corresponding resolvent functions.Furthermore,a condition on qmatrices such that their corresponding Q-functions converge is also obtained.     

一个新非自治超混沌四维二次系统及其电路实现

在三维二次混沌系统的基础上增加一个含控制信号的状态变量,组成一个新的非自治超混沌四维二次系统.该系统的基本动力学特性的变化主要依赖于控制信号频率的改变.通过系统的Lyapunov指数谱、分岔图及数值仿真表明,在不同的频率参数下,该系统能够体现周期、拟周期、混沌、超混沌的动力学特性.最后设计了一个模拟电路,进一步验证了其特性.

Abstract：

Based on the three-dimensional quadratic chaos system, this paper constructs a new four-dimensional quadratic non-autonomous hyperchaos system by adding a state variable with the controlling signal.The change in the basic dynamics characters of this system is mainly realized by varying the frequency of the controlling signal. The different chaos dynamics characters of this system such as periodicity, quasi periodicity, chaos and hyperchaos at different frequencies is shown by Lyapunov spectrum , bifurcation diagram and numerical simulation. The results of the experiment are further shown to be consistent with the numerical simulation by designing an analog electronic circuit.     

相依结构熵及联合熵的分解

把Copula函数引入熵理论,并定义了相依结构熵来度量随机变量之间的相依结构,计论了二维随机向量在单调变换下相依结构熵的不变性并推广到多维的情形.

Abstract：

The copula functions are employed to study the entropy theory and a conception of dependence structure entropy is defined for measuring the dependence structure of random variables.The joint entropy is divided into the dependence structure entropy and the marginal entropy,which is useful of investigating the dependence structure of random variables.In addition,the invariability of dependence structure entro-py of bivariate variables under monotonous transforming is discussed and extended to muhivariable cases.     

判别一类不变凸函数的充分条件

利用微分几何的分析工具,给出了判别一类不变凸函数的充分条件.如果一个可微函数在г-凸集上的г-Hf矩阵是(正定)半正定的,则函数是(严格)不变凸函数.特别地,若函数没有临界点,则函数是局部严格不变凸的.

Abstract：

With the help of differential geometrical tools,a sufficient condition is given to determine the invexity of differentiable functions．A differentiable function is(strictly)invex function if its г-Hf is positive(definite)semidefinite in a г-convex set.Particularly,a function with no critical points is a locally strictly invex function.     

利用周期边界函数对弦振动方程混沌化

给出了用周期边界函数对一阶线性双曲方程混沌化的结果,利用迭代函数混沌特性的结论对该结果进行了严格的证明,并进一步对满足简单条件的初始函数做了数值模拟,模拟结果与理论结论相吻合.     

关于预不变拟凸函数的一些特征

给出了预不变拟凸函数的必要条件,并利用该必要务件证明了严格预不变拟凸函数的等价条件,最后给出了中间点预不变拟凸函数的充分必要条件.

Abstract：

Some characterizations about prequasiinvex functions are obtained.Firstly,a necessary condition about prequasiinvex functions is established.Secondly,a necessary and sufficient condition of strictly prequasiinvex func-tions is provided by making use of the necessary condition.Finally,a necessary and sufficient condition is estab-lished about intermediate-point prequasiinvex functions.     

一类非线性三阶时滞系统的全局渐近稳定性分析

针对一类非线性三阶时滞系统构造出了一个合理的Lyapunov函数,去除了要求lyapunov函数趋于无穷大这个较强的条件约束,只要求系统正半轨线有界,所得的全局渐近稳定性的充分性结果改进了相关文献的结论.最后给出了例子及仿真说明充分条件的有效性.

Abstract：

In this paper,we construct a better Lyapunov function for the nonlinear third order delay system by onlysupposing that the positive half orbit of the system is bounded.The original strong condition is removed,which demands that the Lyapunov function must trend to infinity.The results have improved the conclusions of relevant literatures.At last,examples are given and simulation is made to show the effectiveness of the sufficient conditions.     

水生生态系统中有竞争和捕食效应的一类简单食物网模型的稳定性分析

提出了水生生态系统中有竞争和捕食的一类简单食物网模型.首先讨论了平衡点的存在条件,利用Hurwitz判据分析了局部渐近稳定性;通过构造Lyapunov函数得到了系统全局渐近稳定的条件,并具体解释了其生物含义.从以上讨论中得到了控制3类物种存活、灭绝或共存的4个阈值.生物分析表明,水草和鱼在控制富营养化问题中起着极其重要的作用.

Abstract：

In this paper, a simple food web model with competition and predation in aquatic ecosystems is proposed.The existence conditions of equilibria are discussed and the local asymptotic stability is analyzed.By means of Lya-punov functions, the global asymptotic stability of the model is obtained.Four thresholds, which indicate the coex-istence, survival or extinction of 3 species, are obtained from the above discussions.Bio-analysis shows that aquatic weeds and fish play an important role in the control of eutrophication.     

Bernstein-Kantorovich算子的迭代布尔和在L∞[0,1]中的逼近性质

利用光滑模讨论了Bernstein-Kantorovich算子的迭代布尔和(×)rKn对L∞[0,1]中函数逼近的等价定理.

Abstract：

Using moduli of smoothness, the equivalent theorems on approximation by the iterated Boolean sums(×)rKn of Bernstein-Kantorovich operators Kn for functions which are defined in the space L∞ [0, 1] are studied.