具有饱和传染率、免疫接种和垂直传染的SIR传染病模型的稳定性

研究了一类具有饱和传染率、免疫接种和垂直传染的SIR传染病模型,确定了疾病的基本再生数,得出当疾病的基本再生数小于1时,无病平衡点是全局指数渐近稳定的,当疾病基本再生数大于1时.地方病平衡点是全局渐近稳定的,讨论了其生物意义.     

具有饱和传染率、免疫接种和垂直传染的SIR传染病模型的稳定性北大核心

研究了一类具有饱和传染率、免疫接种和垂直传染的SIR传染病模型,确定了疾病的基本再生数,得出当疾病的基本再生数小于1时,无病平衡点是全局指数渐近稳定的,当疾病基本再生数大于1时.地方病平衡点是全局渐近稳定的,讨论了其生物意义.     

西藏自治区包虫病传播的数学建模及动力学分析

该文通过对包虫病传播机理以及西藏地区包虫病流行现状的研究,构建了一类符合西藏地区实际情况的包虫病动力学模型.利用Lyapunov函数对模型平衡点进行了稳定性分析,证明了无病平衡点和地方病平衡点的全局稳定性.并用收集到的数据,依据模型对基本再生数R₀和包虫病流行情况进行了估计和模拟,结果表明构建的模型符合当地实际传播情况,具有一定的合理性.最后针对归置流浪犬和宣传教育两种防治措施给出了合理的建议.     

一类具有治疗的禽流感模型分析

考虑医疗机构容纳病人的有限性和治疗药物的有限性,建立和研究了一类具有治疗的禽流感传播的数学模型.给出了与禽类系统和人类系统对应的基本再生数的表达式;证明了当病人数量在治疗能力范围内时,禽类系统的基本再生数的大小决定了禽流感是否在禽类和人类中传播;当病人数量超出治疗能力范围时,禽类系统和人类系统对应的两个再生数的大小共同决定禽流感是否在禽类系统和人类系统中传播.     

具有饱和治疗的禽流感动力学模型的研究

提出了一类带有治疗的禽流感动力学模型,用来分析禽流感从禽类向人类传播的过程.由于治疗禽流感的药物十分有限,提出一个带有饱和治疗的模型.通过讨论得知当禽流感疫情已经发生时,通过控制染病的禽类就可抑制禽流感在人类的传播.     

抗病毒治疗对HIV传播的基本再生数的影响

艾滋病是严重危害人类健康的传染病,抗病毒治疗是防治艾滋病的一种公共卫生策略。基于2005—2009年国家免费抗病毒治疗数据和中国艾滋病联合防治评估报告数据,利用一个离散数学模型研究了不同的抗病毒治疗覆盖率和治疗效果对于基本再生数的影响。结果表明,抗病毒治疗后由于感染者体内病毒载量的减少而导致的传染性降低的多少是影响我国艾滋病流行的关键因素。     

具有接种免疫和联合治疗的HIV传染病模型动力学性态研究

建立了对HIV同时进行接种免疫和联合治疗的传染病模型并对其动力学性态进行了分析.当基本再生数R0＜1时,系统存在两个地方病平衡点且无病平衡点局部渐近稳定;当R0＞1时,系统存在唯一的地方病平衡点.进一步构造Lyapunov函数证明了无病平衡点的全局渐近稳定性.通过数值模拟发现系统会发生Hopf分支,当R0＜1时,系统存...     

具有免疫接种且总人口规模变化的SIR传染病模型的稳定性

讨论一类具有预防免疫接种且有效接触率依赖于总人口的SIR传染病模型,给出了决定疾病灭绝和持续生存的基本再生数σ的表达式,在一定条件下证明了疾病消除平衡点的全局稳定性,得到了唯一地方病平衡点的存在性和局部渐近稳定性条件.最后研究了具有双线性传染率和标准传染率的两个具体模型,并证明了当σ>1时该模型地方病平衡点的全局渐近稳定性.     

具有治疗和Beddington-DeAngelis发生率的时滞肺结核传染病模型研究

建立了一类具有疾病治疗和Beddington-DeAngelis发生率的时滞肺结核传染病模型,给出了基本再生数R₀的表达式.当R₀<1时,无病平衡点是全局渐近稳定的,而当R₀>1时,地方病平衡点是全局渐近稳定的.数值模拟演示了所得的理论结果的有效性,研究发现考虑肺结核快速发展阶段的潜伏期时滞及在此期间的发病率能够更好地模拟肺结核病的动力学行为,提高肺结核病的治愈率可以更好的预防和控制肺结核病的传播.     

具有饱和发生率和免疫响应的病毒感染模型的稳定性分析

提出了具有饱和发生率和免疫响应的病毒感染数学模型,得到了基本再生数R_0的表达式.当R_01时,证明了无病平衡点是全局渐近稳定的;当R_01时,得到了免疫耗竭平衡点和持续带毒平衡点局部渐近稳定的条件.     

艾滋病防治资源投入的效果分析

基于GOALS模型的基本思想,建立了效果分析模型,并针对两种不同的资金分配方案,模拟了两种方案对2006—2010年某地艾滋病流行的影响,并对模拟结果进行了分析.     

Immunization and Max–Min Optimal Control

A model of a term structure of interest rates is conceived in which disturbances are unknown and bounded. Arbitrage opportunities are ruled out by imposing suitable constraints to the disturbances. This sets the stage for casting a well-known immunization problem as a max-min optimal control problem. Dynamic programming is then used to obtain the analytical solution to such a problem. In this manner, a well-known immunization policy is proved to be optimal in a dynamic setting.     

动态经济学数学建模及稳定化控制分析

通过考虑需求函数和供给函数受到不连续因素的影响以及引进切换型的控制策略,建立由右端不连续微分方程刻画的非线性价格调整模型.利用微分包含理论和Lyapunov稳定性方法分析不连续价格调整模型的有限时间稳定化控制问题,并给出数值模拟实例进行验证说明.最后,结合动态经济学数学建模提出数学建模教学改革的几点建议.     

A Finite Field Framework for Modeling,Analysis and Control of Finite State Automata

In this paper, we address the modeling, analysis and control of finite state automata, which represent a standard class of discrete event systems. As opposed to graph theoretical methods, we consider an algebraic framework that resides on the finite field &lt;formula form="inline"&gt;${\Op F}_2$&lt;/formula&gt; which is defined on a set of two elements with the operations addition and multiplication, both carried out modulo 2. The key characteristic of the model is its functional completeness in the sense that it is capable of describing most of the finite state automata in use, including non-deterministic and partially defined automata. Starting from a graphical representation of an automaton and applying techniques from Boolean algebra, we derive the transition relation of our finite field model. For cases in which the transition relation is linear, we develop means for treating the main issues in the analysis of the cyclic behavior of automata. This involves the computation of the elementary divisor polynomials of the system dynamics, and the periods of these polynomials, which are shown to completely determine the cyclic structure of the state space of the underlying linear system. Dealing with non-autonomous linear systems with inputs, we use the notion of feedback in order to specify a desired cyclic behavior of the automaton in the closed loop. The computation of an appropriate state feedback is achieved by introducing an image domain and adopting the well-established polynomial matrix method to linear discrete systems over the finite field &lt;formula form="inline"&gt;${\Op F}_2$&lt;/formula&gt;. Examples illustrate the main steps of our method.     

Modeling Optimal Effective Bandwidth of Page-Mode Memory for Stream-Oriented Computations

Memory system performance models have traditionally assumed that individual modules are insensitive to the sequence cf access requests. For current memory components, this assumption is not correct. Furthermore, performance models generally assume a stochastic sequence of reference. For stream-oriented computations, such models of reference are not suitable. This paper derives the optimal effective memory bandwidth achieved by stream-oriented computations at a single module of such memory components.     

Modeling Formation and Removal of Limescale in Water Treatment Systems

Doklady Mathematics - Modeling the processes of formation and removal of limescale formed in water treatment systems is considered to develop closed-loop technologies. Solid deposits that form over...     

Recursive Methods in Modeling and Control of Modular Robotic Systems

This paper addresses the dynamical modeling and control of reconfigurable modular robots. The modular actuators (brushless DC motors with Harmonic Drive gears) for the robots under consideration are connected by rigid links. This way the robot can be assembled in different configurations by rearranging these components. For dynamical modeling the Projection Equation in Subsystem representation is used, taking advantage of its modular structure. Due to the lack of position sensors at the gearbox output shaft, deflections caused by the elasticities in the gears can not be compensated by the PD motor joint controller. Therefore, a correction of the motor trajectory is needed, which can be calculated as part of a flatness based feed-forward control using the exact model of the robot. With the recursive approach proposed in this paper the concept of reconfigurability is retained. For validation a redundant articulated robot arm with seven joints is regarded and results are presented. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Micromechanical Modeling of Woven Fiber Composites for the Construction of Effective Anisotropic Polyconvex Energies

In computer simulations where constitutive equations are considered polyconvex energies can preferably be used because the existence of minimizers is then automatically guaranteed. In this work we investigate the capability to simulate woven fiber composites using polyconvex energies. A virtual experiment of the microstructure of the considered composite is performed and the results are used for the specification of an effective macroscopic anisotropic polyconvex model. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)