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Canard cycle, relaxation oscillation and cross-diffusion induced pattern formation in a slow–fast ecological system with weak Allee effect 具有弱阿利效应的慢-快生态系统中的卡纳周期、弛豫振荡和交叉扩散诱导的模式形成
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108360
Jiawen Jia , Dongpo Hu , Ranjit Kumar Upadhyay , Zhaowen Zheng , Ningning Zhu , Ming Liu
In this paper, we consider a Holling type IV functional response that describes a situation in which the predator’s per capita rate of predation decreases at sufficiently high prey density. Meanwhile it can be transformed into a Holling type II functional response in the limiting sense where predator’s attack rate increases at a decreasing rate with prey density until it becomes satiated. To explore the different dynamics of these two functional responses, we consider the slow–fast dynamic behavior of predator–prey system with Holling type IV and II functional responses, respectively, and make some simple comparisons of the dynamics of the system with these two functional responses. Specifically speaking, in the nonspatial case, firstly, the system with Holling type II functional response does not undergo a higher-codimension Hopf bifurcation. Then, the system with Holling type IV is extensively proved the existence of canard cycles and relaxation oscillations by using a range of analytical methods such as geometric singular perturbation technique, normal form of the slow–fast system, and the way in–way out function. In the spatial case, the temporal systems are extended to reaction–diffusion predator–prey systems. For the reaction–diffusion system with Holling IV, the different types of traveling wave are observed. Moreover, for the reaction–diffusion predator–prey system with Holling II, it is demonstrated that Turing instability occurs, which induces spatial heterogeneity patterns. Finally, the comparisons of the above dynamics of Holling Type IV and II functional responses in the non-spatial and spatial cases, respectively, are presented. From these comparisons, different Holling functional responses may be adopted for species at different stages or states, which is more conducive to maintaining species diversity and coexistence.
在本文中,我们考虑了霍林 IV 型功能响应,它描述了这样一种情况:当猎物密度足够高时,捕食者的人均捕食率会下降。同时,它也可以转化为限制意义上的霍林 II 型功能响应,即捕食者的攻击率随猎物密度的增加而递减,直至饱和。为了探索这两种功能响应的不同动力学特性,我们分别考虑了具有霍林 IV 型和 II 型功能响应的捕食者-猎物系统的慢-快动力学行为,并对具有这两种功能响应的系统的动力学特性进行了一些简单的比较。具体来说,在非空间情况下,首先,具有霍林 II 型功能响应的系统不会发生高维霍普夫分岔。然后,利用几何奇异扰动技术、慢-快系统的正态形式和进-退函数等一系列分析方法,广泛证明了霍林第四型系统存在卡纳循环和弛豫振荡。在空间情况下,时间系统被扩展为反应扩散捕食者-猎物系统。对于具有霍林 IV 的反应扩散系统,可以观察到不同类型的行波。此外,对于霍林 II 的反应扩散捕食者-猎物系统,证明了图灵不稳定性的发生,从而诱发了空间异质性模式。最后,分别对上述非空间和空间情况下霍林 IV 型和 II 型功能响应的动力学进行了比较。从这些比较中可以看出,处于不同阶段或状态的物种可能会采用不同的霍林功能响应,这更有利于维持物种的多样性和共存性。
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引用次数: 0
Two fast finite difference methods for a class of variable-coefficient fractional diffusion equations with time delay 一类有时间延迟的可变系数分数扩散方程的两种快速有限差分法
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108358
Xue Zhang , Xian-Ming Gu , Yong-Liang Zhao
This paper introduces the fast Crank–Nicolson (CN) and compact difference schemes for solving the one- and two-dimensional fractional diffusion equations with time delay. The CN method is employed for temporal discretization, while the fractional centered difference (FCD) formula discretizes the Riesz space derivative. Additionally, a novel fourth-order scheme is developed using compact difference operators to improve accuracy. The convergence and stability of these schemes are rigorously proven. The discretized systems combining Toeplitz-like structures can be effectively solved by Krylov subspace solvers with suitable preconditioners. Each time level of these methods requires a computational complexity of O(plogp) per iteration and a memory of O(p), where p represents the total number of grid points in space. Numerical examples are given to illustrate both the theoretical results and the computational efficiency of the fast algorithm.
本文介绍了用于求解有时间延迟的一维和二维分数扩散方程的快速 Crank-Nicolson(CN)和紧凑差分方案。CN 方法用于时间离散化,而分数中心差分 (FCD) 公式则用于离散化 Riesz 空间导数。此外,还利用紧凑差分算子开发了一种新的四阶方案,以提高精度。这些方案的收敛性和稳定性得到了严格证明。结合了类似托普利兹结构的离散化系统可以通过克雷洛夫子空间求解器和合适的预处理器有效求解。这些方法的每个时间级每次迭代所需的计算复杂度为 O(plogp),内存为 O(p),其中 p 代表空间中网格点的总数。本文给出了数值示例,以说明快速算法的理论结果和计算效率。
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引用次数: 0
SIR models with vital dynamics, reinfection, and randomness to investigate the spread of infectious diseases 具有生命动力学、再感染和随机性的 SIR 模型,用于研究传染病的传播
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108359
Javier López-de-la-Cruz , Alexandre N. Oliveira-Sousa
We investigate SIR models with vital dynamics, reinfection, and randomness at the transmission coefficient and recruitment rate. Initially, we conduct an extensive analysis of the autonomous scenario, covering aspects such as local and global well-posedness, the existence and internal structure of attractors, and the presence of gradient dynamics. Subsequently, we explore the implications of small nonautonomous random perturbations, establishing the continuity of attractors and ensuring their topological structural stability. Additionally, we study scenarios in which both the transmission coefficient and the recruitment rate exhibit time-dependent or random behavior. For each scenario, we establish the existence of attractors and delineate conditions that determine whether the disease is eradicated or reaches an endemic state. Finally, we depict numerical simulations to illustrate the theoretical results.
我们研究了具有生命动力学、再感染以及传播系数和招募率随机性的 SIR 模型。首先,我们对自主情景进行了广泛的分析,包括局部和全局的良好假设、吸引子的存在和内部结构以及梯度动力学的存在等方面。随后,我们探讨了小的非自主随机扰动的影响,确定了吸引子的连续性,并确保其拓扑结构的稳定性。此外,我们还研究了传输系数和招募率都表现出时间依赖性或随机行为的情况。对于每种情况,我们都确定了吸引子的存在,并划定了决定疾病是否根除或达到流行状态的条件。最后,我们通过数值模拟来说明理论结果。
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引用次数: 0
Designing a switching law for Mittag-Leffler stability in nonlinear singular fractional-order systems and its applications in synchronization 为非线性奇异分数阶系统的 Mittag-Leffler 稳定性设计开关定律及其在同步中的应用
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108352
Duong Thi Hong , Do Duc Thuan , Nguyen Truong Thanh
In this work, the stability and synchronization issue of switched singular continuous-time fractional-order systems with nonlinear perturbation are examined. Using the fixed-point principle and S-procedure lemma, a sufficient condition for the existence and uniqueness of the solution to the switched singular fractional-order system is first stated. Next, using the Lyapunov functional method in combination with some techniques related to singular systems and fractional calculus, a switching rule for regularity, impulse-free, and Mittag-Leffler stability is developed based on the formation of a partition of the stability state regions in convex cones. For synchronizing switched fractional singular dynamical systems, we propose a state feedback controller that ensures regularity, impulse-free, and Mittag-Leffler stable in the error closed-loop system. Finally, the ease of use and computational convenience of our proposed methods are illustrated by two numerical examples and a practical example about DC motor controlling an inverted pendulum accompanied by simulation results.
本文研究了具有非线性扰动的切换奇异连续时间分数阶系统的稳定性和同步性问题。首先,利用定点原理和 S 过程两难定理,提出了开关奇异分数阶系统解存在性和唯一性的充分条件。接着,利用 Lyapunov 函数方法,结合奇异系统和分数微积分的一些相关技术,在形成凸锥形稳定状态区域分割的基础上,提出了正则性、无脉冲和 Mittag-Leffler 稳定性的切换规则。针对同步开关分数奇异动力学系统,我们提出了一种状态反馈控制器,可确保误差闭环系统的正则性、无脉冲和 Mittag-Leffler 稳定性。最后,我们通过两个数值示例和一个关于直流电机控制倒立摆的实际示例以及仿真结果,说明了我们提出的方法的易用性和计算便利性。
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引用次数: 0
A comprehensive taxonomy of cellular automata 细胞自动机综合分类法
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108362
Michiel Rollier , Kallil M.C. Zielinski , Aisling J. Daly , Odemir M. Bruno , Jan M. Baetens
Cellular automata (CAs) are fully-discrete dynamical models that have received much attention due to the fact that their relatively simple setup can nonetheless express highly complex phenomena. Despite the model’s theoretical maturity and abundant computational power, the current lack of a complete survey on the ‘taxonomy’ of various families of CAs impedes efficient and interdisciplinary progress. This review paper mitigates that deficiency; it provides a methodical overview of five important CA ‘families’: asynchronous, stochastic, multi-state, extended-neighbourhood, and non-uniform CAs. These five CA families are subsequently presented from four angles. First, a rigorous mathematical definition is given. Second, we map prominent variations within each CA family, as such highlighting mathematical equivalences with types from other families. Third, we discuss the genotype and phenotype of these CA types by means of mathematical tools, indicating when established tools break down. Fourth, we conclude each section with a brief overview of applications related to information theory and mathematical modelling.
细胞自动机(CA)是一种完全离散的动力学模型,由于其相对简单的设置却能表达高度复杂的现象,因而受到广泛关注。尽管该模型理论成熟、计算能力强大,但目前缺乏对各种细胞自动机族 "分类 "的完整调查,这阻碍了高效的跨学科研究进展。这篇综述论文弥补了这一不足;它有条不紊地概述了五个重要的 CA "族":异步 CA、随机 CA、多状态 CA、扩展邻域 CA 和非均匀 CA。随后从四个角度介绍了这五个 CA 系列。首先,给出严格的数学定义。其次,我们绘制了每个 CA 族中的突出变体,从而突出了与其他族类型的数学等价性。第三,我们通过数学工具讨论这些 CA 类型的基因型和表型,并指出既定工具何时失效。第四,我们在每一节的最后简要概述了与信息论和数学建模相关的应用。
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引用次数: 0
Variable gain intermittent stabilization and synchronization for delayed chaotic Lur’e systems 延迟混沌鲁尔系统的可变增益间歇稳定和同步化
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-21 DOI: 10.1016/j.cnsns.2024.108353
Yili Wang , Wu-Hua Chen , Xiaomei Lu
In this paper, a variable gain intermittent control strategy for stabilization and synchronization of chaotic Lur’e systems with time-varying delay is proposed. In contrast to the conventional constant gain intermittent control strategies, the proposed intermittent control strategy allows the control gain to vary with the operation duration of the intermittent controller. The construction of variable control gains is based on a partition scheme on the time-varying working intervals. In order to align with the structure of the variable intermittent control gain function, a pair of partition-dependent piecewise Lyapunov functions are introduced. Two distinct Razumikhin-type analysis techniques, one for the working intervals and the other for the resting intervals, are employed to derive novel criteria for intermittent stabilization and synchronization. The desired intermittent control/synchronization gain functions can be obtained by solving a convex minimization problem, which is capable of minimizing the control width under specified constraints on the gain norm. The numerical results demonstrate that, in comparison with the conventional constant gain strategies, the proposed variable gain intermittent control strategy is capable of efficiently reducing the intermittent control rate.
本文提出了一种可变增益间歇控制策略,用于稳定和同步具有时变延迟的混沌 Lur'e 系统。与传统的恒定增益间歇控制策略不同,本文提出的间歇控制策略允许控制增益随间歇控制器的运行时间而变化。可变控制增益的构建基于时变工作间隔的分区方案。为了与可变间歇控制增益函数的结构保持一致,引入了一对依赖于分区的片断 Lyapunov 函数。采用两种不同的拉祖米欣型分析技术,一种针对工作区间,另一种针对静止区间,从而推导出间歇稳定和同步的新标准。所需的间歇控制/同步增益函数可通过求解凸最小化问题获得,该问题能够在增益规范的特定约束条件下使控制宽度最小化。数值结果表明,与传统的恒定增益策略相比,所提出的可变增益间歇控制策略能够有效降低间歇控制率。
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引用次数: 0
Convergence and superconvergence analysis for a mass conservative, energy stable and linearized BDF2 scheme of the Poisson–Nernst–Planck equations 泊松-纳斯特-普朗克方程的质量保守、能量稳定和线性化 BDF2 方案的收敛性和超收敛性分析
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-17 DOI: 10.1016/j.cnsns.2024.108351
Minghao Li , Dongyang Shi , Zhenzhen Li
In this paper, we consider a linearized BDF2 finite element scheme for the Poisson–Nernst–Planck (PNP) equations. By employing a novel approach, we rigorously derive unconditional optimal error estimates of the numerical solutions in the l(L2) and l(H1) norms, as well as superconvergent results. The key of the convergence and superconvergence analysis lies in deriving the stability of the finite element solutions in some stronger norms. The advantage of this approach is that there is no need to introduce a corresponding time discrete system, so it is more concise than the error split technique in previous literatures. Finally, we carry out two numerical examples to confirm the theoretical findings.
在本文中,我们考虑了泊松-恩斯特-普朗克(PNP)方程的线性化 BDF2 有限元方案。通过采用一种新方法,我们严格推导出数值解在 l∞(L2) 和 l∞(H1) 规范下的无条件最优误差估计以及超收敛结果。收敛和超收敛分析的关键在于推导出有限元解在某些更强规范下的稳定性。这种方法的优点是无需引入相应的时间离散系统,因此比以往文献中的误差分割技术更为简洁。最后,我们通过两个数值实例来证实理论结论。
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引用次数: 0
Minimal cover of high-dimensional chaotic attractors by embedded recurrent patterns 嵌入式循环模式对高维混沌吸引子的最小覆盖
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-16 DOI: 10.1016/j.cnsns.2024.108345
Daniel L. Crane, Ruslan L. Davidchack, Alexander N. Gorban

We propose a general method for constructing a minimal cover of high-dimensional chaotic attractors by embedded unstable recurrent patterns. By minimal cover we mean a subset of available patterns such that the approximation of chaotic dynamics by a minimal cover with a predefined proximity threshold is as good as the approximation by the full available set. The proximity measure, based on the concept of a directed Hausdorff distance, can be chosen with considerable freedom and adapted to the properties of a given chaotic system. In the context of a spatiotemporally chaotic attractor of the Kuramoto–Sivashinsky system on a periodic domain, we demonstrate that the minimal cover can be faithfully constructed even when the proximity measure is defined within a subspace of dimension much smaller than the dimension of space containing the attractor. We discuss how the minimal cover can be used to provide a reduced description of the attractor structure and the dynamics on it.

我们提出了一种通过嵌入式不稳定循环模式构建高维混沌吸引子最小覆盖的通用方法。我们所说的最小覆盖是指可用模式的一个子集,其混沌动力学的近似程度与可用全集的近似程度相当。近似度量基于有向豪斯多夫距离的概念,可以根据给定混沌系统的特性自由选择。我们以周期域上的 Kuramoto-Sivashinsky 系统时空混沌吸引子为背景,证明了即使邻近度量定义在维度远小于包含吸引子的空间维度的子空间内,也能忠实地构建最小覆盖。我们还讨论了如何利用极小盖对吸引子结构及其上的动力学进行简化描述。
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引用次数: 0
A fractional time-stepping method for unsteady thermal convection in non-Newtonian fluids 非牛顿流体中的非稳态热对流的分数时间步进方法
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-16 DOI: 10.1016/j.cnsns.2024.108350
Mofdi El-Amrani , Anouar Obbadi , Mohammed Seaid , Driss Yakoubi

We propose a fractional-step method for the numerical solution of unsteady thermal convection in non-Newtonian fluids with temperature-dependent physical parameters. The proposed method is based on a viscosity-splitting approach, and it consists of four uncoupled steps where the convection and diffusion terms of both velocity and temperature solutions are uncoupled while a viscosity term is kept in the correction step at all times. This fractional-step method maintains the same boundary conditions imposed in the original problem for the corrected velocity solution, and it eliminates all inconsistencies related to boundary conditions for the treatment of the pressure solution. In addition, the method is unconditionally stable, and it allows the temperature to be transported by a non-divergence-free velocity field. In this case, we introduce a methodology to handle the subtle temperature convection term in the error analysis and establish full first-order error estimates for the velocity and the temperature solutions and 1/2-order estimates for the pressure solution in their appropriate norms. Three numerical examples are presented to demonstrate the theoretical results and examine the performance of the proposed method for solving unsteady thermal convection in non-Newtonian fluids. The computational results obtained for the considered examples confirm the convergence, accuracy, and applicability of the proposed time fractional-step method for unsteady thermal convection in non-Newtonian fluids.

我们提出了一种分步法,用于数值求解物理参数随温度变化的非牛顿流体中的非稳态热对流。提出的方法基于粘度分步法,由四个非耦合步骤组成,其中速度解和温度解中的对流项和扩散项都是非耦合的,而校正步骤中始终保持一个粘度项。这种分步法对修正后的速度解保持了与原始问题相同的边界条件,并消除了处理压力解时与边界条件有关的所有不一致之处。此外,该方法是无条件稳定的,并且允许温度通过无发散速度场传输。在这种情况下,我们引入了一种方法来处理误差分析中微妙的温度对流项,并为速度解和温度解建立了完整的一阶误差估计,为压力解建立了适当规范下的 1/2 阶估计。本文给出了三个数值示例来证明理论结果,并检验了所提方法在求解非牛顿流体中的非稳态热对流时的性能。计算结果证实了所提出的时间分步法在非牛顿流体非稳态热对流中的收敛性、准确性和适用性。
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引用次数: 0
A stabilizer free weak Galerkin method with implicit θ-schemes for fourth order parabolic problems 四阶抛物问题的无稳定子弱 Galerkin 方法与隐式 θ 方案
IF 3.4 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-16 DOI: 10.1016/j.cnsns.2024.108349
Shanshan Gu, Fuchang Huo, Huifang Zhou

In this study, we solve the fourth-order parabolic problem by combining the implicit θ-schemes in time for θ[12,1] with the stabilizer free weak Galerkin (SFWG) method. The semi-discrete and full-discrete numerical schemes are proposed. And specifically, the full-discrete scheme is a first-order backward Euler scheme when θ=1, and a second-order Crank–Nicolson scheme for θ=12. Then, we determine the optimal convergence orders of the error in the H2 and L2 norms after analyzing the well-posedness of the schemes. The theoretical findings are validated by numerical experiments.

在本研究中,我们将θ∈[12,1] 时的隐式θ方案与无稳定器弱伽勒金(SFWG)方法相结合,求解了四阶抛物线问题。提出了半离散和全离散数值方案。具体来说,当θ=1 时,全离散方案是一阶后退欧拉方案;当θ=12 时,全离散方案是二阶 Crank-Nicolson 方案。然后,我们在分析了方案的拟合优度后,确定了 H2 和 L2 规范下误差的最佳收敛阶数。数值实验验证了理论结论。
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引用次数: 0
期刊
Communications in Nonlinear Science and Numerical Simulation
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