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Non-orthogonal interpolation on closed interval and convergence 闭区间上的非正交插值及其收敛性
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-14 DOI: 10.1016/j.cam.2026.117454
Guo Qiu Wang , Wei Liang
Building upon the concept of discretely orthogonal bases, this paper develops a generalized interpolation framework, with the classical Lagrange interpolation method serving as a special case. Specifically, for an arbitrary number of specific non-equidistant interpolation nodes, this paper constructs corresponding discretely orthogonal polynomial bases, whose associated orthogonal matrices coincide with the well-known Discrete Cosine Transforms (DCTs). Using these polynomial bases, we show that when interpolation nodes are chosen as extended Chebyshev nodes, the interpolation of continuous functions converge in the square-integrable sense. Furthermore, we prove that the resulting interpolation functions based on extended Chebyshev nodes exhibit uniform convergence in the Hölder continuity class. These results not only provide a rigorous theoretical foundation for polynomial-based signal representation in digital conditioning of sensors, but also suggest a viable candidate for spectral-type approach for numerical schemes for partial differential equations (PDEs).
本文在离散正交基概念的基础上,以经典拉格朗日插值方法为特例,提出了一种广义插值框架。具体地说,对于任意数目的特定的非等距插值节点,本文构造了相应的离散正交多项式基,其所关联的正交矩阵符合众所周知的离散余弦变换(dct)。利用这些多项式基,我们证明了当插值节点选择为扩展Chebyshev节点时,连续函数的插值收敛于平方可积意义。进一步证明了基于扩展Chebyshev节点的插值函数在Hölder连续类中具有一致收敛性。这些结果不仅为传感器数字调理中基于多项式的信号表示提供了严格的理论基础,而且为偏微分方程(PDEs)数值格式的谱型方法提供了可行的候选方法。
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引用次数: 0
Bifurcation, chaotic behaviour, multistability and sensitivity analysis: Exact and numerical analysis of nonlinear dispersive wave equation 分岔、混沌行为、多稳定性和灵敏度分析:非线性色散波动方程的精确和数值分析
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-10 DOI: 10.1016/j.cam.2026.117418
Dean Chou , Ifrah Iqbal , Yasser Alrashedi , Theyab Alrashdi , Hamood Ur Rehman
In this research, we examine the equal-width equation, a basic model for one-dimensional wave propagation in nonlinear fluid dynamics. Using the Kudryashov method, we obtain explicit soliton solutions that reflect the equation’s inherent nonlinear nature, modeling different hydrodynamic phenomena like shallow water waves and internal solitons. The solutions are graphically represented using three-dimensional (3D), contour, density, and two-dimensional (2D) plots to gain further insight into wave evolution. To confirm the analytical solutions, we apply the differential transform method (DTM) for numerical simulations, allowing for comparative analysis between theoretical solitons and their discrete approximations. In addition, stability and modulation instability analyses are conducted to determine the robustness of these wave structures under small perturbations, important for understanding turbulence and energy dissipation in fluids. Furthermore, we perform a bifurcation analysis through the building of phase portraits and vector fields, uncovering complex dynamical behaviors like periodic and chaotic motion in nonlinear fluid systems. In order to expand our investigation, we add a periodic perturbation to investigate chaotic wave interactions, represented through phase space trajectories and time series plots. The perturbed system presents a perturbation with elements of intensity δ and frequency ϕ, enabling us to study how small periodic perturbations influence the dynamical behavior and stability of the nonlinear wave solutions. Finally, we investigate multistability and carry out sensitivity analysis, evaluating how initial conditions affect solution trajectories in a fluid system. Our results are helping toward a deeper understanding of nonlinear wave mechanics and their repercussions in fluid physics. This work addresses the lack of a unified framework by combining exact soliton solutions, numerical validation, and nonlinear dynamical analysis for the equal-width equation.
本文研究了非线性流体力学中一维波传播的基本模型——等宽方程。利用Kudryashov方法,我们得到了反映方程固有非线性性质的显式孤子解,模拟了不同的水动力现象,如浅水波浪和内部孤子。解决方案使用三维(3D)、轮廓、密度和二维(2D)图进行图形表示,以进一步了解波浪演变。为了证实解析解,我们应用微分变换方法(DTM)进行数值模拟,允许在理论孤子与其离散近似之间进行比较分析。此外,还进行了稳定性和调制不稳定性分析,以确定这些波结构在小扰动下的鲁棒性,这对理解流体中的湍流和能量耗散很重要。此外,我们通过建立相画像和矢量场进行分岔分析,揭示了非线性流体系统的复杂动力学行为,如周期运动和混沌运动。为了扩大我们的研究,我们添加了一个周期扰动来研究混沌波的相互作用,通过相空间轨迹和时间序列图来表示。扰动系统呈现出具有强度δ和频率φ元素的扰动,使我们能够研究小的周期性扰动如何影响非线性波解的动力学行为和稳定性。最后,我们研究了多稳定性并进行了灵敏度分析,以评估初始条件如何影响流体系统中的溶液轨迹。我们的结果有助于更深入地理解非线性波动力学及其在流体物理中的影响。这项工作通过结合精确孤子解、数值验证和等宽方程的非线性动力学分析来解决缺乏统一框架的问题。
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引用次数: 0
A C-FISTA-type proximal point algorithm for strongly quasiconvex pseudomonotone equilibrium problems 强拟凸伪单调平衡问题的c - fista型近点算法
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-24 DOI: 10.1016/j.cam.2026.117504
Grace Nnennaya Ogwo , Chinedu Izuchukwu , Yekini Shehu
This paper presents a C-FISTA-type proximal point algorithm for solving strongly quasiconvex pseudomonotone equilibrium problems. Our proposed method consists of two momentum terms, a correction term, and the proximal point algorithm. We establish the convergence of our proposed method under standard assumptions. Furthermore, we obtain the sublinear and linear convergence rates of our proposed method. Finally, we present a numerical test for solving equilibrium problems to illustrate the effectiveness and versatility of our proposed method.
提出一种求解强拟凸伪单调平衡问题的c - fista型近点算法。该方法由两个动量项、一个修正项和近点算法组成。在标准假设条件下,证明了所提方法的收敛性。进一步,我们得到了该方法的次线性收敛速率和线性收敛速率。最后,我们给出了一个求解平衡问题的数值测试,以说明我们提出的方法的有效性和通用性。
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引用次数: 0
Two block product-type preconditioners for double saddle point problems 双鞍点问题双块产品型预调节器
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-22 DOI: 10.1016/j.cam.2026.117476
Na-Na Wang , Ji-Cheng Li
In this paper, a class of product-type (PT) preconditioners for generalized saddle point problems recently proposed in [N. Wang, J. Li, A class of preconditioners based on symmetric-triangular decomposition and matrix splitting for generalized saddle point problems, IMA J. Numer. Anal., (2023) 43, 2998–3025] are extended to solve the double saddle point problems arising from the modeling of liquid crystal directors. By combining augmented Lagrangian (AL) technique, two specific block PT preconditioners are developed, which are applied appropriately with the efficient conjugate gradient (CG) and conjugate residual (CR) methods although neither the preconditioners nor the double saddle point systems are symmetric positive definite (SPD). This is the biggest advantage and novelty of the proposed preconditioners. The proposed preconditioned CG (PCG) and preconditioned CR (PCR) methods actually belong to the categories of nonstandard inner product CG and nonstandard inner product CR methods, respectively. Moreover, the PCG and PCR algorithms and their convergence theorems are given. Theoretical and experimental analysis shows that the spectra of the preconditioned matrices are contained within real and positive intervals which are very sharp if the involved parameters are chosen appropriately. In addition, the practically useful values for parameters are easy to obtain. Numerical experiments are presented to illustrate the rapidity, effectiveness and numerical stability of the proposed preconditioners and show the advantages of the proposed preconditioners over the existing state-of-the-art preconditioners for double saddle point problems.
本文利用文献[N]中提出的一类广义鞍点问题的积型预调节器。王俊,李俊,一类基于对称三角分解和矩阵分裂的广义鞍点问题预条件,数学学报。分析的。[j],(2023) 43, 2998-3025],用于解决液晶定向器建模中出现的双鞍点问题。结合增广拉格朗日(AL)技术,开发了两种特定的块PT预条件,并将其与有效共轭梯度(CG)和共轭残差(CR)方法相结合,尽管预条件和双鞍点系统都不是对称正定的(SPD)。这是所提出的预调节器的最大优点和新颖之处。所提出的预条件CG (PCG)和预条件CR (PCR)方法实际上分别属于非标准内积CG和非标准内积CR方法的范畴。并给出了PCG和PCR算法及其收敛定理。理论和实验分析表明,如果选取适当的参数,预条件矩阵的谱包含在实区间和正区间内,且谱非常清晰。此外,实际有用的参数值很容易获得。通过数值实验验证了所提预调节器的快速性、有效性和数值稳定性,并证明了所提预调节器相对于现有双鞍点问题预调节器的优越性。
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引用次数: 0
A centered Newton method for nonlinear complementarity problem 非线性互补问题的中心牛顿法
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-26 DOI: 10.1016/j.cam.2026.117473
F. Arenas , R. Pérez , M. Gonzalez-Lima , C.A. Arias
In this paper we present a centered Newton type algorithm for solving the nonlinear complementarity problem by a reformulation of the problem as a nonlinear system of equations with nonnegativity constraints. The proposed algorithm considers centered Newton directions projected over the feasible set in order to maintain iterate feasibility. We present theoretical and numerical results for the proposal.
本文通过将非线性互补问题重新表述为具有非负性约束的非线性方程组,给出了求解非线性互补问题的中心牛顿型算法。该算法考虑了在可行集上投影的中心牛顿方向,以保持迭代的可行性。我们给出了该建议的理论和数值结果。
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引用次数: 0
Characterizations of solution sets of nonsmooth mathematical programming problems 非光滑数学规划问题解集的刻画
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-10 DOI: 10.1016/j.cam.2026.117422
Shashi Kant Mishra , Dheerendra Singh
In this paper, we consider a nonsmooth mathematical programming problem and establish the characterization of solution sets. We also give a normal cone condition for nonsmooth mathematical programming problems to obtain optimality conditions using Lagrange multipliers and tangential subdifferentials. We also provide some examples in support of our results.
本文研究了一类非光滑数学规划问题,建立了解集的刻画。利用拉格朗日乘子和切向次微分,给出了非光滑数学规划问题的正锥条件,得到了最优性条件。我们还提供了一些例子来支持我们的结果。
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引用次数: 0
Regularization via generalized operational matrices: Theory and applications in machine learning classification 广义运算矩阵的正则化:机器学习分类的理论与应用
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-19 DOI: 10.1016/j.cam.2026.117459
Saba Asgarzadeh , M.R. Eslahchi
In this research, we introduce new classes of regularization matrices constructed using generalized operational matrices of the Caputo fractional derivative. Experimental results confirm the performance and effectiveness of the proposed method. In another part of this study, the obtained matrices are applied to classification tasks in machine learning. The results demonstrate improved classification accuracy and more effective data representation.
在本研究中,我们引入了用Caputo分数阶导数的广义运算矩阵构造的一类新的正则化矩阵。实验结果验证了该方法的性能和有效性。在本研究的另一部分中,将得到的矩阵应用于机器学习中的分类任务。结果表明,该方法提高了分类精度和数据表示效率。
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引用次数: 0
A positivity-preserving subspace method based on neural networks for solving diffusion equations in the weak form 基于神经网络的保正子空间方法求解弱形式扩散方程
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-12 DOI: 10.1016/j.cam.2026.117406
Pengyuan Liu , Zhaodong Xu , Zhiqiang Sheng
In this paper, we propose a positivity-preserving subspace method, termed PSNNW, which is based on neural networks formulated in the weak form for solving diffusion equations. The method employs a monotonic positivity-preserving nonlinear functions to transform the original equations into mathematically equivalent forms. The numerical solution of the transformed equation is subsequently computed using a subspace neural network method in the weak form designed for nonlinear problems. In this method, neural networks are employed to train and generate basis functions, which are then incorporated into iterative schemes, such as Picard iteration, to solve the problem within the Galerkin framework. Owing to the positivity-preserving transformation, the numerical solution of the original equation is guaranteed to remain positive. Numerical experiments demonstrate that the proposed method yields nonnegative solutions with high accuracy, confirming its simplicity and effectiveness in preserving positivity.
本文提出了一种基于弱形式神经网络的保正子空间方法PSNNW,用于求解扩散方程。该方法采用单调保正非线性函数将原方程转化为数学等价形式。然后利用针对非线性问题设计的弱形式的子空间神经网络方法计算变换后方程的数值解。该方法利用神经网络训练和生成基函数,并将基函数结合到Picard迭代等迭代方案中,在Galerkin框架内求解问题。由于进行了保正变换,保证了原方程的数值解为正。数值实验表明,该方法得到的非负解精度高,证明了该方法的简单性和保正性的有效性。
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引用次数: 0
Bound-preserving adaptive time-stepping methods with energy stability for simulating compressible gas flow in poroelastic media 具有能量稳定性的保界自适应时步法模拟孔隙弹性介质中可压缩气体流动
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-28 DOI: 10.1016/j.cam.2026.117552
Huangxin Chen , Yuxiang Chen , Jisheng Kou , Shuyu Sun
In this paper, we present an efficient numerical method to address a thermodynamically consistent gas flow model in porous media involving compressible gas and deformable rock. The accurate modeling of gas flow in porous media often poses significant challenges due to their inherent nonlinearity, the coupling between gas and rock dynamics, and the need to preserve physical principles such as mass conservation, energy dissipation and molar density boundedness. The system is further complicated by the need to balance computational efficiency with the accuracy and stability of the numerical scheme. To tackle these challenges, we adopt a stabilization approach that is able to preserve the original energy dissipation while achieving linear energy-stable numerical schemes. We also prove the convergence of the adopted linear iterative method. At each time step, the stabilization parameter is adaptively updated using a simple and explicit formula to ensure compliance with the original energy dissipation law. The proposed method uses adaptive time stepping to improve computational efficiency while maintaining solution accuracy and boundedness. The adaptive time step size is calculated explicitly at each iteration, ensuring stability and allowing for efficient handling of highly dynamic scenarios. A mixed finite element method combined with an upwind scheme is employed as spatial discretization to ensure mass conservation and stability. Finally, we conduct a series of numerical experiments to validate the performance and robustness of the proposed numerical method.
在本文中,我们提出了一种有效的数值方法来处理涉及可压缩气体和可变形岩石的多孔介质中热力学一致的气体流动模型。由于多孔介质固有的非线性、气体和岩石动力学之间的耦合以及需要保持质量守恒、能量耗散和摩尔密度有界等物理原理,对多孔介质中气体流动的精确建模常常面临重大挑战。由于需要平衡计算效率与数值格式的准确性和稳定性,系统进一步复杂化。为了应对这些挑战,我们采用了一种稳定方法,能够在保持原始能量耗散的同时实现线性能量稳定的数值格式。并证明了所采用的线性迭代方法的收敛性。在每个时间步长,采用简单明了的公式自适应地更新稳定化参数,以保证符合原能量耗散规律。该方法采用自适应时间步进,在保证求解精度和有界性的同时提高了计算效率。自适应时间步长是在每次迭代中明确计算的,确保了稳定性,并允许有效地处理高度动态的场景。采用混合有限元法结合迎风方案进行空间离散,以保证质量守恒和稳定性。最后,我们进行了一系列的数值实验来验证所提出的数值方法的性能和鲁棒性。
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引用次数: 0
A new C1-continuous variational integration scheme for mechanical systems subjected to acceleration-dependent forces 一个新的c1 -连续变分积分方案的机械系统受到加速度相关的力
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-10-01 Epub Date: 2026-02-24 DOI: 10.1016/j.cam.2026.117509
Ping Zhou , Songhan Zhang , Hui Ren , Zheng Chen , Wei Fan
The C1-continuity of calculated state curves is crucial for engineering problems subject to acceleration-dependent forces, such as hydrodynamic loads and control forces. Conventional variational integration schemes with prominent energy and momentum preserving properties are favored to calculate the dynamics of mechanical systems, however, can sometimes lose their efficacy due to a lack of continuity. In this work, a novel C1-continuous variational integration scheme is developed within a simple and general construction framework, ensuring the continuity of the generalized coordinates and their first derivative at the discrete-time points. This scheme is constructed by approximating generalized coordinates and velocities using Hermite polynomials within a certain time span with the action integral computed numerically. This framework greatly simplifies the derivation and implementation by avoiding the summation of discrete node variations, and it is also suitable for constructing other variational schemes based on Lagrangian polynomials of various orders. The algorithmic characteristics, including stability, dissipation, period elongation, and convergence order, are theoretically analyzed. The momentum-preserving and nearly energy-preserving properties are numerically demonstrated. Moreover, practical engineering problems subject to acceleration-dependent forces are investigated, which have well confirmed the feasibility of the proposed C1-continuous variational scheme in practical dynamic analyses.
计算状态曲线的c1 -连续性对于受加速度相关力(如流体动力载荷和控制力)影响的工程问题至关重要。传统的变分积分方案具有突出的能量和动量保持特性,有利于计算机械系统的动力学,但有时会由于缺乏连续性而失去其有效性。本文提出了一种新颖的c1 -连续变分积分方案,该方案在一个简单和通用的构造框架内,保证了广义坐标及其一阶导数在离散时间点上的连续性。该方案是在一定时间范围内用Hermite多项式逼近广义坐标和速度,并通过数值计算得到作用积分来构造的。该框架避免了离散节点变化的求和,大大简化了推导和实现,也适用于构造其他基于不同阶次拉格朗日多项式的变分格式。从理论上分析了算法的稳定性、耗散、周期延长和收敛顺序等特性。数值证明了其保持动量和几乎保持能量的性质。此外,研究了受加速度相关力影响的实际工程问题,很好地证实了c1 -连续变分格式在实际动力分析中的可行性。
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引用次数: 0
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Journal of Computational and Applied Mathematics
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