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Global stability of a delay HCV dynamics model with cellular proliferation 具有细胞增殖的延迟HCV动力学模型的全局稳定性
Q3 Mathematics Pub Date : 2022-09-10 DOI: 10.5206/mase/14918
Alexis Nangue, Armel Willy Fokam Tacteu, Ayouba Guedlai
In this work, we propose and investigate a delay cell population model of hepatitis C virus (HCV) infection with cellular proliferation, absorption effect and a nonlinear incidence function. First of all, after having shown the existence of the local solutions of our model, we show the existence of the global solutions and positivity. Moreover, we determine the uninfected equilibrium point and the basic reproduction rate R0, which is a threshold number in mathematical epidemiology. After showing the existence and uniqueness of the infected equilibrium point, we proceed to the study of the local and global stability of this equilibrium. We show that if  R0 < 1, the uninfected equilibrium point is globally asymptotically stable, which means that the disease will disappear and if  R0 > 1, we have a unique infected equilibrium that is globally asymptotically stable under some conditions. Finally, we perform some numerical simulations to illustrate the obtained theoretical results.
在这项工作中,我们提出并研究了一个具有细胞增殖、吸收效应和非线性发病函数的丙型肝炎病毒(HCV)感染的延迟细胞群模型。首先,在展示了我们模型的局部解的存在性之后,我们展示了全局解和正性的存在性。此外,我们确定了未感染的平衡点和基本繁殖率R0,这是数学流行病学中的阈值。在证明了受感染平衡点的存在性和唯一性之后,我们开始研究该平衡点的局部和全局稳定性。我们证明,如果R0<1,未感染的平衡点是全局渐近稳定的,这意味着疾病将消失;如果R0>1,我们有一个唯一的感染平衡点,在某些条件下是全局渐进稳定的。最后,我们进行了一些数值模拟来说明所获得的理论结果。
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引用次数: 1
Macroscopic Analysis Of The Viscous-Diffusive Traffic Flow Model 粘性扩散交通流模型的宏观分析
Q3 Mathematics Pub Date : 2022-07-09 DOI: 10.5206/mase/14626
Gabriel Obed Fosu, A. Adu-Sackey, J. Ackora-Prah
Second-order macroscopic traffic models are characterized by a continuity equation and an acceleration equation. Convection, anticipation, relaxation, diffusion, and viscosity are the predominant features of the different classes of the acceleration equation. As a unique approach, this paper presents a new macro-model that accounts for all these dynamic speed quantities. This is done to determine the collective role of these traffic quantities in macroscopic modeling. The proposed model is solved numerically to explain some phenomena of a multilane traffic flow.  It also includes a linear stability analysis. Furthermore, the evolution of speed and density wave profiles are presented under the perturbation of some parameters.
二阶宏观交通模型由连续性方程和加速度方程表征。对流、预期、松弛、扩散和粘性是不同类别加速度方程的主要特征。作为一种独特的方法,本文提出了一种新的宏观模型,该模型考虑了所有这些动态速度量。这样做是为了确定这些交通量在宏观建模中的集体作用。对所提出的模型进行了数值求解,以解释多车道交通流的一些现象。它还包括线性稳定性分析。此外,还给出了在某些参数扰动下速度和密度波剖面的演化过程。
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引用次数: 0
A mathematical model of quorum quenching in biofilm colonies and its potential role as an adjuvant for antibiotic treatment 生物膜菌落群体猝灭的数学模型及其作为抗生素治疗辅助剂的潜在作用
Q3 Mathematics Pub Date : 2022-06-16 DOI: 10.5206/mase/14612
M. Ghasemi, Viktoria Freingruber, C. Kuttler, H. Eberl
We extend a previously presented mesoscopic (i.e. colony scale) mathematical model of the reaction of bacterial biofilms to antibiotics. In that earlier model, exposure to antibiotics evokes two responses: inactivation as the antibiotics kill the bacteria, and inducing a quorum sensing based stress response mechanism upon exposure to small sublethal dosages. To this model we add now quorum quenching as an adjuvant to antibiotic therapy. Quorum quenchers are modeled like enzymes that degrade the quorum sensing signal concentration. The resulting model is a quasilinear system of seven reaction-diffusion equations for the dependent variables volume fractions of upregulated (protected), downregulated (unprotected) and inert (inactive) biomass [particulate substances], and for concentrations of a growth promoting nutrient, antibiotics, quorum sensing signal, and quorum quenchers [dissolved substances]. The biomass fractions are subject to two nonlinear diffusion effects: (i) degeneracy, as in the porous medium equation, where biomass vanishes, and (ii) a super-diffusion singularity where as it attains its theoretically possible maximum. We study this model in numerical simulations. Our simulations suggest that for maximum efficacy quorum quenchers should be applied early on before quorum sensing induction in the biofilm can take place, and that an antibiotic strategy that by itself might not be successful can be notably improved upon if paired with quorum quenchers as an adjuvant. 
我们扩展了先前提出的细菌生物膜对抗生素反应的介观(即菌落尺度)数学模型。在早期的模型中,暴露于抗生素会引起两种反应:抗生素杀死细菌时的失活,以及暴露于小剂量亚致死剂量时诱导基于群体感应的应激反应机制。在这个模型中,我们现在添加quorum淬火作为抗生素治疗的辅助剂。群体猝灭器的模型类似于降低群体感应信号浓度的酶。由此产生的模型是一个由七个反应扩散方程组成的拟线性系统,这些方程是关于上调(受保护)、下调(不受保护)和惰性(不活跃)生物质[颗粒物质]的因变量体积分数,以及促进生长的营养物、抗生素、群体感应信号和群体猝灭剂[溶解物质]的浓度。生物质组分受到两种非线性扩散效应的影响:(i)简并,如在多孔介质方程中,生物质消失;(ii)超扩散奇点,当它达到理论上可能的最大值时。我们对该模型进行了数值模拟研究。我们的模拟表明,为了获得最大的效果,群体猝灭剂应该在生物膜中群体感应诱导发生之前尽早应用,并且如果将群体猝灭剂作为佐剂配对,则抗生素策略本身可能不成功,可以显着改善。
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引用次数: 0
Global Analysis of a generalized viral infection temporal model with cell-to-cell transmission and absorption effect under therapy 治疗下具有细胞间传播和吸收效应的广义病毒感染时间模型的全局分析
Q3 Mathematics Pub Date : 2022-05-15 DOI: 10.5206/mase/14663
Alexis Nangue, Paulin Tiomo Lemofouet, Simon Ndouvatama, Kengne Emmanuel
In virus dynamics, when a cell is infected, the number of virions outside the cells is reduced by one: this phenomenon is known as absorption effect. Most mathematical in vivo models neglect this phenomenon. Virus-to-cell infection and direct cell-to-cell transmission are two fundamental modes whereby viruses can be propagated and transmitted.  In this work, we propose a new virus dynamics model, which incorporates both modes and takes into account the absorption effect and treatment. First we show mathematically and biologically the well-posedness of our model preceded by the result on the existence and the uniqueness of the solutions. Also, an explicit formula for the basic reproduction number R0 of the model is determined. By analyzing the characteristic equations we establish the local stability of the uninfected equilibrium and the infected equilibrium in terms of R0. The global behavior of the model is investigated by constructing an appropriate Lyapunov functional for uninfected equilibrium and by applying a geometric approach to the study of the infected equilibrium. Numerical simulations are carried out, to confirm the obtained theoretical result in a particular case.
在病毒动力学中,当一个细胞被感染时,细胞外的病毒粒子数量减少一个:这种现象被称为吸收效应。大多数体内数学模型都忽略了这一现象。病毒-细胞感染和直接细胞-细胞传播是病毒繁殖和传播的两种基本方式。在这项工作中,我们提出了一个新的病毒动力学模型,它结合了这两种模式,并考虑了吸收效应和治疗。首先,我们从数学和生物学上证明了模型的适定性,然后给出了解的存在性和唯一性。并给出了模型基本再现数R0的显式公式。通过对特征方程的分析,建立了以R0表示的未感染平衡点和感染平衡点的局部稳定性。通过构造一个适当的Lyapunov泛函来研究模型的全局行为,并应用几何方法来研究感染平衡。通过数值模拟验证了所得到的理论结果。
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引用次数: 1
Modeling road surface potholes within the macroscopic flow framework 在宏观流动框架下对路面凹坑进行建模
Q3 Mathematics Pub Date : 2022-05-15 DOI: 10.5206/mase/14625
Gabriel Obed Fosu, J. Opong, B. E. Owusu, S. Naandam
The continual wearing of road surfaces results to crack and holes called potholes. These road surface irregularities often elongate travel time. In this paper, a second-order macroscopic traffic model is therefore proposed to account for these road surface irregularities that affect the smooth flow of vehicular traffic. Though potholes do vary in shape and size, for simplicity the paper assumes that all potholes have conic resemblances. The impact of different sized potholes on driving is experimented using fundamental diagrams. Besides, the width of these holes, driver reaction time amid these irregularities also determine the intensity of the flow rate and vehicular speed. Moreover, a local cluster analysis is performed to determine the effect of a small disturbance on flow. The results revealed that the magnitude of amplification on a road surface with larger cracks is not as severe as roads with smaller size holes, except at minimal and jam density where all amplifications quickly fade out.
路面的持续磨损导致裂缝和洞称为坑洞。这些凹凸不平的路面常常延长旅行时间。因此,本文提出了一个二阶宏观交通模型来解释这些影响车辆交通顺畅的路面不规则性。虽然坑洞的形状和大小各不相同,但为了简单起见,本文假设所有坑洞都具有圆锥相似性。用基本图试验了不同大小的坑穴对行车的影响。此外,这些孔洞的宽度和驾驶员在这些不规则情况下的反应时间也决定了流量的强度和车辆的速度。此外,还进行了局部聚类分析,以确定小扰动对流动的影响。结果表明,裂缝较大的路面上的放大幅度不如孔洞较小的路面严重,但在最小和堵塞密度下,所有放大都迅速消退。
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引用次数: 1
HOW DOES THE LATENCY PERIOD IMPACT THE MODELING OF COVID-19 TRANSMISSION DYNAMICS? 潜伏期如何影响COVID-19传播动力学建模?
Q3 Mathematics Pub Date : 2022-03-30 Epub Date: 2022-02-20 DOI: 10.5206/mase/14537
Ben Patterson, Jin Wang

We introduce two mathematical models based on systems of differential equations to investigate the relationship between the latency period and the transmission dynamics of COVID-19. We analyze the equilibrium and stability properties of these models, and perform an asymptotic study in terms of small and large latency periods. We fit the models to the COVID-19 data in the U.S. state of Tennessee. Our numerical results demonstrate the impact of the latency period on the dynamical behaviors of the solutions, on the value of the basic reproduction numbers, and on the accuracy of the model predictions.

我们引入两个基于微分方程组的数学模型,研究潜伏期与COVID-19传播动态之间的关系。我们分析了这些模型的平衡和稳定性,并在小潜伏期和大潜伏期方面进行了渐近研究。我们将这些模型与美国田纳西州的COVID-19数据拟合。我们的数值结果证明了潜伏期对解的动力学行为、对基本再现数的值以及对模型预测精度的影响。
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引用次数: 3
Dynamics of discrete predator- prey system with fear effect and density dependent birth rate of the prey species 具有恐惧效应的离散捕食-食饵系统动力学和密度依赖的食饵物种出生率
Q3 Mathematics Pub Date : 2022-02-06 DOI: 10.5206/mase/14496
D. Mukherjee
This paper analyses a discrete predator-prey system with fear effect and density dependent birth rate of the prey species. The fixed points of the system are determined and their stability is examined. The criterion for Neimark-Sacker bifurcation and flip bifurcation is developed. The chaotic orbit at an unstable fixed point can be stabilized by applying the state feedback control method. Numerically, we illustrate our analytical findings and observe the complex behaviour of the system that leads to stable state to chaotic one.
本文分析了一个具有恐惧效应和密度依赖的离散捕食系统。确定了系统的不动点,并对其稳定性进行了检验。建立了Neimark-Sacker分岔和翻转分岔的判据。应用状态反馈控制方法可以稳定不稳定不动点的混沌轨道。从数字上讲,我们说明了我们的分析结果,并观察了系统的复杂行为,该行为导致稳定状态变为混沌状态。
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引用次数: 0
Dynamics of a stoichiometric producer-grazer model with maturation delay 具有成熟延迟的化学计量生产者-食草动物模型的动力学
Q3 Mathematics Pub Date : 2022-02-06 DOI: 10.5206/mase/14332
Hua Zhang, Hao Wang, Ben Niu
Ecological stoichiometry provides a multi-scale approach to study macroscopic phenomena via microscopic lens. A stoichiometric producer-grazer model with maturation delay is proposed and studied in this paper. The interaction between stoichiometry and delay is novel and leads to more interesting insights beyond classical delay-driven periodic solutions. For example, the period doubling route to chaos can occur as the minimal phosphorous:carbon ratio in producer decreases. Mathematically, we establish the conditions for the existence and stability of positive equilibria, and study the occurrence of Hopf bifurcation at positive equilibria. Analytic results show that delay can change the number and stability of positive equilibria through transcritical bifurcation, saddle-node bifurcation and Hopf bifurcation, and it further determines the grazer's extinction. Our model with a small delay behaves like LKE model in terms of light intensity, and Rosenzweig's paradox of enrichment exists in a suitable light intensity. We plot bifurcation diagrams and show rich dynamics driven by delay, light intensity, phosphorous availability, and conversion efficiency, including that a large delay can drive the grazer to go extinct in an intermediate light intensity that is favorable for the survival of the grazer when there is no delay; a limit cycle can appear, then disappear as the delay increases; given the same initial condition, solutions with different delay values can tend to different attractors.
生态化学计量提供了一种通过微观透镜研究宏观现象的多尺度方法。本文提出并研究了一个具有成熟延迟的化学计量生产者-食草动物模型。化学计量和延迟之间的相互作用是新颖的,并在经典延迟驱动的周期解之外带来了更有趣的见解。例如,当生产者中的最小磷碳比降低时,可能会出现周期加倍的混沌途径。在数学上,我们建立了正平衡存在和稳定的条件,并研究了正平衡下Hopf分岔的发生。分析结果表明,时滞可以通过跨临界分岔、鞍节点分岔和Hopf分岔改变正平衡的个数和稳定性,并进一步决定了掠器的灭绝。我们的小延迟模型在光强方面与LKE模型类似,在适当的光强下存在Rosenzweig富集悖论。我们绘制了分叉图,显示了由延迟、光强、磷有效性和转化效率驱动的丰富动力学,包括大的延迟可以在中等光强下驱动食草动物灭绝,这有利于食草动物在没有延迟的情况下生存;极限循环可能出现,然后随着延迟的增加而消失;给定相同的初始条件,具有不同延迟值的解可以趋向于不同的吸引子。
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引用次数: 0
Application of ant colony optimization metaheuristic on set covering problems 蚁群优化元启发式算法在集覆盖问题中的应用
Q3 Mathematics Pub Date : 2022-01-20 DOI: 10.5206/mase/14018
C. A. Buhat, Jerson Ken Villamin, G. Cuaresma
Ant Colony Optimization (ACO) metaheuristic is a multi-agent system in which the behaviour of each ant is inspired by the foraging behaviour of real ants to solve optimization problem. Set Covering Problems (SCP), on the other hand, deal with maximizing the coverage of every subset while the weight nodes used must be minimized. In this paper, ACO was adapted and used to solve a case of Set Covering Problem. The adapted ACO for solving the SCP was implemented as a computer program using SciLab 5.4.1. The problem of determining the optimal location of Wi-Fi Access Points using the 802.11n protocol in the UP Los Banos Math Building was solved using this metaheuristic. Results show that in order to have 100% coverage of the MB, 7 access points are required. Methodology of the study can be adapted and results of the study can be used by decision makers on related optimization problems.
蚁群优化(ACO)元启发式是一个多智能体系统,其中每个蚂蚁的行为都受到真实蚂蚁觅食行为的启发,以解决优化问题。另一方面,集覆盖问题(SCP)处理的是最大化每个子集的覆盖,而使用的权重节点必须最小化。本文将ACO方法应用于一个集覆盖问题的求解。使用SciLab 5.4.1将用于解决SCP的自适应ACO实现为计算机程序。使用这种元启发式方法解决了在UP Los Banos数学大楼中使用802.11n协议确定Wi-Fi接入点的最佳位置的问题。结果显示,为了实现MB的100%覆盖,需要7个接入点。研究方法可以进行调整,决策者可以将研究结果用于相关的优化问题。
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引用次数: 0
On approximating initial data in some linear evolutionary equations involving fraction Laplacian 关于部分拉普拉斯算子线性演化方程中初始数据的逼近
Q3 Mathematics Pub Date : 2022-01-19 DOI: 10.5206/mase/13511
R. Karki
We study an inverse problem of recovering the intial datum in a one-dimensional linear equation with Dirichlet boundary conditions when finitely many values (samples) of the solution at a suitably fixed space loaction and suitably chosen finitely many later time instances are known. More specifically, we do this. We consider a one-dimentional linear evolutionary equation invliing a Dirichlet fractional Laplacian and the unknown intial datum f that is assumed to be in a suitable subset of a Sovolev space. Then we investigate how to construct a sequence of future times and choose n so that from n samples taken at a suitably fixed space location and the first n terms of the time sequence we can constrcut an approximation to f with the desired accuracy. 
我们研究了一个具有Dirichlet边界条件的一维线性方程的初始数据恢复逆问题,当已知在适当固定的空间位置上的解的有限多个值(样本)和适当选择的有限多稍后的时间实例时。更具体地说,我们这样做。我们考虑了一个一维线性进化方程,该方程包含Dirichlet分数拉普拉斯算子和未知的初始数据f,假设初始数据f在Sovolev空间的合适子集中。然后,我们研究如何构建未来时间序列,并选择n,以便从在适当固定的空间位置采集的n个样本和时间序列的前n项中,我们可以构造出具有所需精度的f的近似值。
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引用次数: 0
期刊
Mathematics in applied sciences and engineering
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