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An approximate solution for stochastic Fitzhugh–Nagumo partial differential equations arising in neurobiology models 神经生物学模型中出现的随机 Fitzhugh-Nagumo 偏微分方程的近似解法
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-17 DOI: 10.1002/mma.10471
D. Uma, H. Jafari, S. Raja Balachandar, S. G. Venkatesh, S. Vaidyanathan
In this paper, approximate solutions for stochastic Fitzhugh–Nagumo partial differential equations are obtained using two‐dimensional shifted Legendre polynomial (2DSLP) approximation. The problem's suitability and solvability are confirmed. The convergence analysis for the proposed methodology and the error analysis in the norm are carried out. Using Maple software, an algorithm is created and implemented to arrive at the numerical solution. The solution thus obtained is compared with the exact solution and the solution obtained using the explicit order RK1.5 method.
本文利用二维移位 Legendre 多项式(2DSLP)近似法求得了随机 Fitzhugh-Nagumo 偏微分方程的近似解。证实了问题的适用性和可解性。对提出的方法进行了收敛性分析和规范误差分析。使用 Maple 软件创建并实施了一种算法,以获得数值解。将获得的解与精确解以及使用显式阶 RK1.5 方法获得的解进行了比较。
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引用次数: 0
Similarity and consimilarity of hyper‐dual generalized quaternions 超二元广义四元数的相似性和相通性
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-17 DOI: 10.1002/mma.10488
Yasemin Alagöz, Gözde Özyurt
The aim of this paper is to investigate similarity and consimilarity of hyper‐dual generalized quaternions and their matrices. For this purpose, we give different conjugates according to the generalized quaternionic units . We present ‐consimilarity of hyper‐dual generalized quaternions and their matrices except hyper‐dual ‐quaternions. For the generalization consisting of hyper‐dual coefficients quaternion and split quaternion, we search ‐consimilarity and ‐consimilarity with the help of ‐conjugate and ‐conjugate. We also give ‐coneigenvalues and ‐coneigenvectors of the matrices of these generalizations. In addition, we examine right coneigenvalue problem in generalized quaternion matrices for real and split quaternions. The complex matrix representation obtained through the complex adjoint matrix representation of this generalization is introduced, and its properties are presented. Besides, we give algebraic methods for the concept of right coneigenvalues and coneigenvectors for matrices, which are the generalization of real quaternion and split quaternion.
本文旨在研究超二元广义四元数及其矩阵的相似性和相通性。为此,我们根据广义四元数单位给出了不同的共轭。除了超二元四元数之外,我们还提出了超二元广义四元数及其矩阵的-相似性。对于由超二元系数四元数和分裂四元数组成的广义四元数,我们借助-共轭和-共轭来搜索-相似性和-相似性。我们还给出了这些广义矩阵的-锥特征值和-锥特征向量。此外,我们还研究了实四元数和分裂四元数的广义四元数矩阵的右锥特征值问题。我们介绍了通过这种广义的复邻接矩阵表示而得到的复矩阵表示,并介绍了它的性质。此外,我们还给出了实四元数和分裂四元数广义矩阵的右锥特征值和锥特征向量概念的代数方法。
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引用次数: 0
Uniform exponential stability approximations of semi‐discretization schemes for two hybrid systems 两个混合系统半离散化方案的统一指数稳定性近似值
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-14 DOI: 10.1002/mma.10484
Lu Zhang, Fu Zheng, Sizhe Wang, Zhongjie Han
The uniform exponential stabilities (UESs) of two hybrid control systems comprised of a wave equation and a second‐order ordinary differential equation are investigated in this study. Linear feedback law and local viscosity are considered, as are nonlinear feedback law and internal anti‐damping. The hybrid system is first reduced to a first‐order port‐Hamiltonian system with dynamical boundary conditions, and the resulting system is discretized using the average central‐difference scheme. Second, the UES of the discrete system is obtained without prior knowledge of the exponential stability of the continuous system. The frequency domain characterization of UES for a family of contractive semigroups and the discrete multiplier approach are used to validate the main conclusions. Finally, the Trotter–Kato theorem is used to perform a convergence study on the numerical approximation approach. Most notably, the exponential stability of the continuous system is derived by the convergence of energy and UES, which is a novel approach to studying the exponential stability of some complex systems. Numerical simulation is used to validate the effectiveness of the numerical approximating strategy.
本研究探讨了由波浪方程和二阶常微分方程组成的两个混合控制系统的均匀指数稳定性(UES)。考虑了线性反馈定律和局部粘性,以及非线性反馈定律和内部反阻尼。首先将混合系统简化为具有动态边界条件的一阶端口-哈密尔顿系统,并使用平均中心差分方案对所得到的系统进行离散化。其次,在不预先知道连续系统指数稳定性的情况下,获得离散系统的 UES。利用收缩半群族 UES 的频域特征和离散乘法来验证主要结论。最后,利用 Trotter-Kato 定理对数值逼近方法进行了收敛性研究。最值得注意的是,通过能量和 UES 的收敛性推导出连续系统的指数稳定性,这是研究某些复杂系统指数稳定性的一种新方法。通过数值模拟验证了数值逼近策略的有效性。
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引用次数: 0
A new representation for the solution of the Richards‐type fractional differential equation 理查兹型分数微分方程解法的新表示法
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-13 DOI: 10.1002/mma.10394
Iz‐iddine EL‐Fassi, Juan J. Nieto, Masakazu Onitsuka
Richards in [35] proposed a modification of the logistic model to model growth of biological populations. In this paper, we give a new representation (or characterization) of the solution to the Richards‐type fractional differential equation for , where is a continuously differentiable function on and is a positive real constant. The obtained representation of the solution can be used effectively for computational and analytic purposes. This study improves and generalizes the results obtained on fractional logistic ordinary differential equation.
理查兹在文献[35]中提出了对逻辑模型的修改,以模拟生物种群的增长。在本文中,我们给出了理查兹型分式微分方程解的新表示(或表征),其中 , 为连续可微分函数, 为正实数常数。所获得的解的表示可以有效地用于计算和分析目的。这项研究改进并推广了分式逻辑常微分方程的研究成果。
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引用次数: 0
Clifford‐valued linear canonical wavelet transform and the corresponding uncertainty principles 克利福德值线性小波变换和相应的不确定性原理
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-12 DOI: 10.1002/mma.10468
Shahbaz Rafiq, Mohammad Younus Bhat
The present article establishes a novel transform known as Clifford‐valued linear canonical wavelet transform which is intended to represent ‐dimensional Clifford‐valued signals at various scales, locations, and orientations. The suggested transform is capable of representing signals in the Clifford domain in addition to inheriting the characteristics of the Clifford wavelet transform. In the beginning, we demonstrate the proposed transform by the help of ‐dimensional difference of Gaussian wavelets. We then establish the fundamental properties of the proposed transform like Parseval's formula, inversion formula, and characterization of its range using Clifford linear canonical transform and its convolution. To conclude our work, we derive an analog of Heisenberg's and local uncertainty inequalities for the proposed transform.
本文建立了一种称为克利福德值线性典型小波变换的新型变换,旨在表示不同尺度、位置和方向的-维克利福德值信号。建议的变换除了继承克利福德小波变换的特点外,还能表示克利福德域中的信号。首先,我们借助高斯小波的-维差分来演示所建议的变换。然后,我们利用克利福德线性规范变换及其卷积建立了所提变换的基本特性,如帕斯瓦尔公式、反转公式和范围特征。最后,我们为所提出的变换推导出了海森堡不确定性和局部不确定性不等式。
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引用次数: 0
Pattern dynamics in a water–vegetation model with cross‐diffusion and nonlocal delay 具有交叉扩散和非局部延迟的水-植被模型中的模式动力学
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-12 DOI: 10.1002/mma.10480
Gaihui Guo, Jing You, Khalid Ahmed Abbakar
In semiarid areas, the positive feedback effect of vegetation and soil moisture plays an indispensable role in the water absorption process of plant roots. In addition, vegetation can absorb water through the nonlocal interaction of roots. Therefore, in this article, we consider how the interactions between cross‐diffusion and nonlocal delay affect vegetation growth. Through mathematical analysis, the conditions for the occurrence of the Turing pattern in the water–vegetation model are obtained. Meanwhile, using the multi‐scale analysis method, the amplitude equation near the Turing bifurcation boundary is obtained. By analyzing the stability of the amplitude equation, the conditions for the appearance of Turing patterns such as stripes, hexagons, and mixtures of stripes and hexagons are determined. Some numerical simulations are given to illustrate the analytical results, especially the evolution processes of vegetation patterns depicted under different parameters.
在半干旱地区,植被和土壤水分的正反馈效应在植物根系的吸水过程中发挥着不可或缺的作用。此外,植被还能通过根系的非局部相互作用吸收水分。因此,本文考虑了交叉扩散和非局部延迟之间的相互作用如何影响植被生长。通过数学分析,得到了水-植被模型中图灵模式出现的条件。同时,利用多尺度分析方法,得到了图灵分岔边界附近的振幅方程。通过分析振幅方程的稳定性,确定了条纹、六边形、条纹与六边形混合等图灵图案出现的条件。为说明分析结果,特别是不同参数下植被图案的演变过程,给出了一些数值模拟。
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引用次数: 0
Viscoelasticity, logarithmic stresses, and tensorial transport equations 粘弹性、对数应力和张量传输方程
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-12 DOI: 10.1002/mma.10469
Gennaro Ciampa, Giulio G. Giusteri, Alessio G. Soggiu
We introduce models for viscoelastic materials, both solids and fluids, based on logarithmic stresses to capture the elastic contribution to the material response. The matrix logarithm allows to link the measures of strain, that naturally belong to a multiplicative group of linear transformations, to stresses, that are additive elements of a linear space of tensors. As regards the viscous stresses, we simply assume a Newtonian constitutive law, but the presence of elasticity and plastic relaxation makes the materials non‐Newtonian. Our aim is to discuss the existence of weak solutions for the corresponding systems of partial differential equations in the nonlinear large‐deformation regime. The main difficulties arise in the analysis of the transport equations necessary to describe the evolution of tensorial measures of strain. For the solid model, we only need to consider the equation for the left Cauchy–Green tensor, while for the fluid model, we add an evolution equation for the elastically‐relaxed strain. Due to the tensorial nature of the fields, available techniques cannot be applied to the analysis of such transport equations. To cope with this, we introduce the notion of charted weak solution, based on non‐standard a priori estimates, that lead to a global‐in‐time existence of solutions for the viscoelastic models in the natural functional setting associated with the energy inequality.
我们引入了基于对数应力的粘弹性材料(包括固体和流体)模型,以捕捉材料响应的弹性贡献。矩阵对数允许将自然属于线性变换乘法组的应变测量值与应力联系起来,应力是张量线性空间的加法元素。至于粘性应力,我们只需假设牛顿构成定律,但弹性和塑性松弛的存在使材料成为非牛顿材料。我们的目的是讨论相应的偏微分方程系统在非线性大变形体系中是否存在弱解。主要困难在于分析描述张量应变演变所需的传输方程。对于固体模型,我们只需要考虑左 Cauchy-Green 张量的方程,而对于流体模型,我们还需要考虑弹性松弛应变的演化方程。由于场的张量性质,现有技术无法用于分析此类传输方程。为了解决这个问题,我们引入了基于非标准先验估计的图表弱解概念,从而在与能量不等式相关的自然函数设置中,为粘弹性模型找到了全局时间内存在的解。
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引用次数: 0
Stability analysis and error estimation based on difference spectral approximation for Allen–Cahn equation in a circular domain 基于圆域中艾伦-卡恩方程差分谱近似的稳定性分析和误差估计
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-12 DOI: 10.1002/mma.10481
Zhenlan Pan, Jihui Zheng, Jing An
For the first time, we propose an efficient difference spectral approximation for Allen–Cahn equation in a circular domain. Firstly, we introduce the polar coordinate transformation and derive the equivalent form of Allen–Cahn equation under this coordinate system, as well as the corresponding essential polar condition. Then, by using first‐order Euler and second‐order backward difference methods in the temporal direction, we deduce the first‐order and second‐order semi‐implicit schemes, based on which the first‐order and second‐order fully discrete schemes are established by employing Legendre‐Fourier spectral approximation in the spatial direction. In addition, the energy stability and error estimations for the two types of numerical schemes are theoretically proved. Finally, we provide some numerical examples, the results of which demonstrate the stability and convergence of the algorithm.
我们首次提出了圆域中 Allen-Cahn 方程的高效差分谱近似方法。首先,我们引入极坐标变换,并推导出该坐标系下 Allen-Cahn 方程的等效形式,以及相应的基本极坐标条件。然后,在时间方向上采用一阶欧拉法和二阶后向差分法,推导出一阶和二阶半隐式方案,在此基础上,在空间方向上采用 Legendre-Fourier 光谱近似法,建立了一阶和二阶全离散方案。此外,我们还从理论上证明了这两种数值方案的能量稳定性和误差估计。最后,我们提供了一些数值示例,其结果证明了算法的稳定性和收敛性。
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引用次数: 0
Exponential stability of a class of quaternion‐valued memristor‐based neural network with time‐varying delay via M‐matrix 通过 M 矩阵实现一类基于四元数值忆阻器的时变延迟神经网络的指数稳定性
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-11 DOI: 10.1002/mma.10486
Shengye Wang, Yanchao Shi, Jun Guo
This paper investigates the problems of exponential stability for a class of quaternion‐valued memristor‐based neural networks. By using M‐matrix theory and fixed point theorem, the existence and uniqueness of the equilibrium point of quaternion‐valued neural network are proved, respectively. Then, by combining M‐matrix with exponential stability theory, a non‐factorization method is obtained by using some inequality techniques to give the effective conditions of global exponential stability of quaternion‐valued memristor‐based neural network with time‐varying delay. Finally, numerical examples are given to demonstrate the validity of the derived results.
本文研究了一类基于四元数值忆阻器的神经网络的指数稳定性问题。利用 M 矩阵理论和定点定理,分别证明了四元数值神经网络平衡点的存在性和唯一性。然后,将 M 矩阵与指数稳定性理论相结合,利用一些不等式技术获得了一种非因子化方法,给出了具有时变延迟的基于四元数值忆阻器的神经网络的全局指数稳定性的有效条件。最后,给出了数值示例来证明推导结果的正确性。
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引用次数: 0
Bayesian inversion of a fractional elliptic system derived from seismic exploration 对地震勘探得出的分数椭圆系统进行贝叶斯反演
IF 2.9 3区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2024-09-10 DOI: 10.1002/mma.10474
Yujiao Li
In this paper, we concentrate on the Bayesian inversion of a dispersion‐dominated fractional Helmholtz (DDFH) equation, which has been introduced in studies concerning seismic exploration. To establish the inversion theory, we meticulously examine the DDFH equation. We transform it into a system comprising both fractional‐ and integer‐order elliptic equations, extending the conventional definition of the spectral fractional Laplace operator to accommodate non‐homogeneous boundary conditions. Subsequently, we establish the well‐posedness theory for scenarios involving both small and large wavenumbers. Our proof hinges upon the regularity attributes of select fractional elliptic equations and capitalizes fully on the structural peculiarities of the elliptic system, which distinguish it from classical cases. Thereafter, we focus on the inverse medium scattering problem pertinent to the DDFH equation, framed within the Bayesian statistical framework. We address two scenarios: one devoid of model reduction errors and another characterized by such errors—arising from the implementation of certain absorbing boundary conditions. More precisely, based on the properties of the forward operator, well‐posedness of the posterior measures have been proved in both cases, which provide an opportunity to quantify the uncertainties of this problem.
本文主要研究地震勘探研究中引入的贝叶斯反演分散主导型分数亥姆霍兹(DDFH)方程。为了建立反演理论,我们仔细研究了 DDFH 方程。我们将其转化为一个由分数阶和整数阶椭圆方程组成的系统,扩展了频谱分数拉普拉斯算子的传统定义,以适应非均质边界条件。随后,我们为涉及小波数和大波数的情况建立了良好拟合理论。我们的证明依赖于所选分数椭圆方程的正则属性,并充分利用了椭圆系统的结构特殊性,这使其有别于经典情况。之后,我们将重点放在贝叶斯统计框架内与 DDFH 方程相关的反介质散射问题上。我们讨论了两种情况:一种是没有模型还原误差,另一种是由于实施某些吸收边界条件而产生的模型还原误差。更确切地说,基于前向算子的特性,我们证明了这两种情况下的后验量值的可实现性,这为量化该问题的不确定性提供了机会。
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引用次数: 0
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Mathematical Methods in the Applied Sciences
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