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Search Results: 1 - 10 of 104229 matches for " Tailei Zhang "
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Global stability for delay SIR epidemic model with vertical transmission  [PDF]
Junli Liu, Tailei Zhang
Open Journal of Applied Sciences (OJAppS) , 2012, DOI: 10.4236/ojapps.2012.24B001
Abstract: A SIR epidemic model with delay, saturated contact rate and vertical transmission is considered. The basic reproduction number is calculated. It is shown that this number characterizes the disease transmission dynamics: if, there only exists the disease-free equilibrium which is globally asymptotically stable; if, there is a unique endemic equilibrium and the disease persists, sufficient cond- itions are obtained for the global asymptotic stability of the endemic equilibrium.
Stochastically Perturbed Epidemic Model with Time Delays
Tailei Zhang
Discrete Dynamics in Nature and Society , 2012, DOI: 10.1155/2012/454073
Stochastically Perturbed Epidemic Model with Time Delays
Tailei Zhang
Discrete Dynamics in Nature and Society , 2012, DOI: 10.1155/2012/454073
Abstract: We investigate a stochastic epidemic model with time delays. By using Liapunov functionals, we obtain stability conditions for the stochastic stability of endemic equilibrium. 1. Introduction In [1], Zhen et al. introduced a deterministic SIRS model where is the number of susceptible population, is the number of infective members and is the number of recovered members. is the rate at which population is recruited, is the death rate for classes , , and , is the disease-induced death rate, is the transmission rate, is the recovery rate, and is the loss of immunity rate. Equation (1.1) represents an SIRS model with epidemics spreading via a vector, whose incubation time period is a distributed parameter over the interval . is the limit superior of incubation time periods in the vector population. The is usually nonnegative and continuous and is the distribution function of incubation time periods among the vectors and . To be more general, the following model is formulated: The positive constants , , and represent the death rates of susceptibles, infectives, and recovered, respectively. It is natural biologically to assume that . If , model (1.2) was considered in [2–5]. For and fixed delay, the global asymptotic stability of (1.2) was considered in [6]. The basic reproduction number for (1.2) is If , the system (1.2) has just one disease-free equilibrium ; otherwise, if , the disease-free equilibrium is still present, but there is also a unique positive endemic equilibrium , given by , , . 2. Stability Analysis of the Atochastic Delay Model Since environmental fluctuations have great influence on all aspects of real life, then it is natural to study how these fluctuations affect the epidemiological model (1.2). We assume that stochastic perturbations are of white noise type and that they are proportional to the distances of from , respectively. Then the system (1.2) will be reduced to the following form: Here, ,?? , and are constants, and represents a three-dimensional standard Wiener processes. This system has the same equilibria as system (1.2). We assume that ; we discuss the stability of the endemic equilibrium of (2.1). The stochastic system (2.1) can be centered at its endemic equilibrium by the changes of variables , , . By this way, we obtain In order to investigate the stability of endemic equilibrium of system (2.1), we study the stability of the trivial solution of system (2.2). First, consider the stochastic functional differential equation Let be the probability space, the family of -algebra, , the space of -adapted functions , , , the??
Extinction in Nonautonomous Discrete Lotka-Volterra Competitive System with Pure Delays and Feedback Controls
Ling Zhang,Zhidong Teng,Tailei Zhang,Shujing Gao
Discrete Dynamics in Nature and Society , 2009, DOI: 10.1155/2009/656549
Abstract: The paper discusses a nonautonomous discrete time Lotka-Volterra competitive system with pure delays and feedback controls. New sufficient conditions for which a part of the -species is driven to extinction are established by using the method of multiple discrete Lyapunov functionals.
Existence of Positive Periodic Solutions of a Prey-Predator System with Several Delays

Xu Wenxiong,Zhang Tailei,Xu Zongben,

数学物理学报(A辑) , 2008,
Abstract: A kind of non-autonomous prey-predator system with Holling II response function and several delays is studied. By the coincidence degree theory, the authors construct a set of sufficient conditions to prove the existence of global positive periodic solution. Some known results are improved.
An Efficient and Concise Algorithm for Convex Quadratic Programming and Its Application to Markowitz’s Portfolio Selection Model  [PDF]
Zhongzhen Zhang, Huayu Zhang
Technology and Investment (TI) , 2011, DOI: 10.4236/ti.2011.24024
Abstract: This paper presents a pivoting-based method for solving convex quadratic programming and then shows how to use it together with a parameter technique to solve mean-variance portfolio selection problems.
Investigation and Analysis of Sexual Harassment in Corporate Workplace of China  [PDF]
Xiaobing Zhang, Zewei Zhang
Sociology Mind (SM) , 2012, DOI: 10.4236/sm.2012.23038
Abstract: At present, sexual harassment in domestic workplace has a high probability of occurrence, which causes more and more attention. In this paper, the form of sexual harassment in workplace, and how to solve the sexual harassment were investigated and analyzed through questionnaires; and countermeasures and management suggestions were put forward from three aspects of corporate, employees and family.
Chaos Control in a Discrete Ecological System  [PDF]
Limin Zhang, Chaofeng Zhang
International Journal of Modern Nonlinear Theory and Application (IJMNTA) , 2012, DOI: 10.4236/ijmnta.2012.13011
Abstract: In research [1], the authors investigate the dynamic behaviors of a discrete ecological system. The period-double bifurcations and chaos are found in the system. But no strategy is proposed to control the chaos. It is well known that chaos control is the first step of utilizing chaos. In this paper, a controller is designed to stabilize the chaotic orbits and enable them to be an ideal target one. After that, numerical simulations are presented to show the correctness of theoretical analysis.
Crystallization and Characterization of a New Fluorescent Molecule Based on Schiff Base  [PDF]
Dehua Zhang, Xiaoyan Zhang
Journal of Crystallization Process and Technology (JCPT) , 2013, DOI: 10.4236/jcpt.2013.31004

In this analysis, the single crystal of schiff base has been synthesized and the purity of material has been increased by repeated recrystallization process. Single crystal was grown by adopting the method growing in a slow evaporation solution using ethanol as solvent at room temperature. A new fluorescent molecule based on Schiff base has been synthesised and its binding properties investigated by fluorescence spectroscopy to show that it can selectively bind Cu2+ with fluorescence quenching.

Mathematical Reasoning of Economic Intervening Principle Based on “Yin Yang Wu Xing” Theory in Traditional Chinese Economics (I)  [PDF]
Ziqing Zhang, Yingshan Zhang
Modern Economy (ME) , 2013, DOI: 10.4236/me.2013.42016

By using mathematical reasoning, this paper demonstrates the economic intervening principle: “Virtual disease is to fill his mother but real disease is to rush down his son” and “ Strong inhibition of the same time, support the weak” based on “Yin Yang Wu Xing” Theory in Traditional Chinese Economics (TCE). We defined generalized relations and generalized reasoning, introduced the concept of steady multilateral systems with two non-compatibility relations, and discussed its energy properties. Later based on the intervening principle of TCE and treated the economic society as a steady multilateral system, it has been proved that the intervening principle above is true. The kernel of this paper is the existence and reasoning of the non-compatibility relations in steady multilateral systems, and it accords with the oriental thinking model.

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