从健康系统工程看口腔影像学大数据研究伦理

口腔健康被世界卫生组织(WHO)列为人体健康10大标准之一,口腔中微生物及其代谢产物已被证明与人体多种系统性疾病相关.随着口腔影像学、宏基因组学、宏转录组学和蛋白质组学等信息技术的快速发展,使得从基于大数据的健康系统论开展口腔疾病和健康研究变得可行,各种医学伦理问题也相应而生.鉴于我国健康大数据研究现状,文章针对口腔影像学大数据研究,提出知情同意,健全法律法规,分级伦理审查的建议,其核心是明晰数据所有权,以保护患者权益为核心,同时引导和规范临床科研的创新与探索,提高伦理委员会工作效率.     

人体下肢系统着陆瞬间数学模型的建立与解析

人体的肢体运动是多关节复杂运动,呈现多环节链状系统特性,人体着陆瞬间冲击是复杂物理作用过程,而人体又是一粘弹性体,对着陆瞬间冲击存在一系列动态响应;针对系统非线性特征,利用主导关节分解理论,分别建立人体下肢多关节运动状态的联合数学模型;基于哈密顿体系对人体下肢运动耦合问题数学模型进行解析;运用ANSYS软件对人体着陆瞬间下肢系统进行仿真求解,以期为剖析下肢复合运动机理提供理论依据.     

具有体液免疫和细胞免疫的反应扩散HIV病毒模型

本文基于HIV病毒在人体内的动态变化过程和人体的两类免疫机制,提出了一种具有体液免疫和细胞免疫的反应扩散HIV病毒模型.利用比较原理和极值原理证明了该模型非负解的存在性及有界性.通过定义不同患病阶段下两个关键阈值,并利用李亚普诺夫理论分析了无病平衡点和两类患病平衡点的全局动力学行为.最后,利用数值实例子验证了理论结果正确性.     

带有时滞中性技术进步资产投资系统的积累率的辨识

对一类带有时滞的中性技术进步的资产投资系统,运用积分方程和泛函分析理论,讨论了此非线性资产投资系统的积累率的辨识问题.利用Banach空间理论,得到了辨识问题解的存在唯一性.     

一类带小时滞的非线性快慢系统的渐近解

研究了一类带小时滞的非线性快慢系统的初始值问题,在一定假设条件下,利用奇异摄动理论和校正函数法构造了该问题的形式渐近解,并利用微分不等式理论证明了渐近解的一致有效性.最后进行了算例分析,结果显示时滞能对快慢系统产生重要影响,并表明所述摄动方法是一个行之有效的近似解析方法.从而,可以利用得到的渐近解对系统的动力学行为进行更深层次地分析与研究.     

基于模糊理论的闭环供应链定价决策研究

考虑一个单周期二级模糊闭环供应链系统.模糊性存在于制造过程、再制造过程、需求过程和回收过程.利用模糊理论和博弈论理论等知识,分别在集中式和分散式决策方式下给出了制造商和零售商的最优定价决策,以及分散决策方式下的系统协调策略,并且利用数值算例对所得结果进行了分析.     

带有分段常数变量的Lorenz系统的稳定性和分支

本文研究一类带有分段常数变量的Lorenz系统的稳定性和分支行为.首先通过计算转化得到Lorenz系统对应的差分系统,利用线性稳定性理论讨论平衡点局部渐近稳定的充要条件.其次选择差分系统三个参数的一个参数为分支参数,利用分支理论研究平衡点处产生Neimark-Sacker分支不变闭曲线的充要条件,并使用分支理论给出判断分支不变闭曲线的稳定性的阈值.最后数值模拟验证了理论分析的正确性.     

延迟积分-微分方程的敏感度和Hopf分岔分析

本文考虑了一类延迟积分-微分方程的Hopf分岔分析.利用敏感性方程,确定了一个合适的Hopf参数.基于Hopf分岔理论得到,当系统存在Hopf分岔时系统参数必须满足的条件.为了得到Hopf参数的精确值,进一步讨论了延迟积分-微分方程的离散形式,利用Newton迭代法,得到了参数的逼近值.最后,数值仿真说明了我们的理论的有效性.     

几何批量需求下库存系统稳态分析

研究了几何批量需求下库存系统模型.假设顾客到达的时间间隔、顾客接受服务的时间、系统补货的时间以及系统中服务员休假的时间均服从指数分布,其中库存为空时服务员开始多重休假.利用拟生灭过程和矩阵几何解理论得到了系统的稳态分布,在此基础上进一步分析了性能指标以及成本函数.最后,利用遗传算法对系统参数进行了敏感性分析.结果可以为实际库存管理提供理论依据.     

一类离散生态经济系统稳定性与分支研究

本文研究了一个离散生态经济模型的稳定性和分支问题.利用离散奇异系统理论,中心流形定理及Neimark-Sacker分支理论,得到了系统关于不动点的稳定性和Neimark-Sacker分支的有关结果,并与相应的连续模型进行对比分析.推广了文献[5]的结果.     

两类两种群动力学方程的稳定性分析

本文研究两种群动力学方程平衡点的稳定性.讨论两个捕食者-食饵-领地模型,模型用1微分方程描述,模型2用积分微分方程描述.得出平衡点稳定的条件.所得结果指出可实现总体的种群稳定而不管局部的绝灭.     

Bifurcation of a three molecular saturated reaction with impulsive input

Although impulsive differential equations have become a widely concerned subject and a lot of models with impulsive effect have been studied in recent years, biochemical reaction models with impulsive input are rarely studied. In this paper, we consider an irreversible three molecular reaction model with impulsive input. By using the Floquet theorem and the method for the small parameter of impulsive differential equations, we obtain sufficient conditions for asymptotical stability and global stability of the given system. The existence of a positive periodic solution is also studied by the bifurcation theory. Further, we also show that our given conditions are right by numerical simulations.     

关于趋化性的O-S型方程定态解的稳定性

本文利用由线性逼近得到稳定性的相关理论,通过对平衡点进行稳定性分析,讨论了一类趋化性方程常定态的稳定性.文中给出了相应的稳定性判别准则,并将这些结果应用于一些重要的生物模型.     

Global stability analysis of epidemiological models based on Volterra–Lyapunov stable matrices

In this paper, we study the global dynamics of a class of mathematical epidemiological models formulated by systems of differential equations. These models involve both human population and environmental component(s) and constitute high-dimensional nonlinear autonomous systems, for which the global asymptotic stability of the endemic equilibria has been a major challenge in analyzing the dynamics. By incorporating the theory of Volterra–Lyapunov stable matrices into the classical method of Lyapunov functions, we present an approach for global stability analysis and obtain new results on some three- and four-dimensional model systems. In addition, we conduct numerical simulation to verify the analytical results.     

General criteria for asymptotic and exponential stabilities of neural network models with unbounded delays

For a family of differential equations with infinite delay, we give sufficient conditions for the global asymptotic, and global exponential stability of an equilibrium point. This family includes most of the delayed models of neural networks of Cohen-Grossberg type, with both bounded and unbounded distributed delay, for which general asymptotic and exponential stability criteria are derived. As illustrations, the results are applied to several concrete models studied in the literature, and a comparison of results is given.     

加权微分建模的初步研究

加权建模是必要的,微分建模是重要的,把二者结合起来,进行加权微分建模既必要也重要.给出了常用模型的微分建模结果,讨论了加权建模中的计算和权重选择问题,探讨了加权微分建模的思路和方法,并结合典型数据验证了该方法的有效性和稳定性.象加权建模一样,加权微分建模的精度、实用价值等,是和权重确定得合理与否紧密相联;应先进行模拟,以与近期实际值或典型样本相差最小的参数所对应的模型为准.     

Geometric approach to global asymptotic stability for the SEIRS models in epidemiology

In this paper, we present a more general criterion for the global asymptotic stability of equilibria for nonlinear autonomous differential equations based on the geometric criterion developed by Li and Muldowney. By applying this criterion, we obtain some results for the global asymptotic stability of SEIRS models with constant recruitment and varying total population size. Based on these results, we give a complete affirmative answer to Liu–Hethcote–Levin conjecture. Furthermore, an affirmative answer to Li–Graef–Wang–Karsai’s problem for SEIR model with permanent immunity and varying total population size is given.     

Stability analysis of mathematical models for nonlinear growth kinetics of breast cancer stem cells

Cancer stem cells are responsible for tumor survival and resurgence and are thus essential in developing novel therapeutic strategies against cancer. Mathematical models can help understand cancer stem and differentiated cell interaction in tumor growth, thus having the potential to help in designing experiments to develop novel therapeutic strategies against cancer. In this paper, by using theory of functional and ordinary differential equations, we study the existence and stability of nonlinear growth kinetics of breast cancer stem cells. First, we provide a sufficient condition for the existence and uniqueness of the solution for nonlinear growth kinetics of breast cancer stem cells. Then we study the uniform asymptotic stability of the zero solution. By using linearization techniques, we also provide a criteria for uniform asymptotic stability of a nontrivial steady‐state solution with and without time delays. We present a theorem from complex analysis that gives certain conditions that allow for this criteria to be satisfied. Next, we apply these theorems to a special case of the system of functional differential equations that has been used to model nonlinear growth kinetics of breast cancer stem cells. The theoretical results are further justified by numerical testing examples. Consistent with the theories, our numerical examples show that the time delays can disrupt the stability. All the results can be easily extended to study more general cell lineage models. Copyright © 2017 John Wiley & Sons, Ltd.     

Global dynamics of Nicholson-type delay systems with applications

Models of marine protected areas and B-cell chronic lymphocytic leukemia dynamics that belong to the Nicholson-type delay differential systems are proposed. To study the global stability of the Nicholson-type models we construct an exponentially stable linear system such that its solution is a solution of the nonlinear model. Explicit conditions of the existence of positive global solutions, lower and upper estimations of solutions, and the existence and uniqueness of a positive equilibrium were obtained. New results, obtained for the global stability and instability of equilibria solutions, extend known results for the scalar Nicholson models. The conditions for the stability test are quite practical, and the methods developed are applicable to the modeling of a broad spectrum of biological processes. To illustrate our finding, we study the dynamics of the fish populations in Marine Protected Areas.     

Delay equations with fluctuating delay related to the regenerative chatter II: analysis of reduced bifurcation equation

In this article, we study the reduced bifurcation equations of the nonlinear delay differential equations with periodic delays, which models the machine tool chatter with continuously modulated spindle speed to determine the periodic solutions and analyze the tool motion. Analytical results show both modest increase of stability and existence of periodic solutions close to the new stability boundary.