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Divergence-free and curl-free moving least squares approximations 无散度和无旋度的移动最小二乘近似
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-01-03 DOI: 10.1016/j.cam.2026.117338
Davoud Mirzaei , Vahid Mohammadi
This paper presents a vector-valued moving least squares (MLS) approximation for reconstructing vector fields that are divergence-free or curl-free. The proposed method constructs analytically divergence-free or curl-free shape functions by applying appropriate differential operators to a stream (potential) function approximated using the MLS method. The procedure involves solving a sparse linear least squares problem, for which the Conjugate Gradient Least Squares (CGLS) algorithm is employed to reduce computational costs compared to the direct solvers. The approach relies solely on a set of scattered nodes in the computational domain and requires no background triangulation. We provide error bounds for the approximation and support the theoretical bounds with numerical experiments. Additionally, we demonstrate the application of the divergence-free MLS approximation to the numerical solution of Darcy’s flow equations.
本文提出了一种用于重建无散度或无旋度矢量场的向量值移动最小二乘近似。该方法通过对使用MLS方法近似的流(势)函数应用适当的微分算子来构造解析无散度或无旋流的形状函数。该过程涉及求解一个稀疏线性最小二乘问题,与直接求解相比,该问题采用了共轭梯度最小二乘(CGLS)算法来减少计算成本。该方法仅依赖于计算域中的一组分散节点,不需要背景三角剖分。我们给出了近似的误差范围,并用数值实验支持了理论范围。此外,我们还演示了无散度MLS近似在达西流动方程数值解中的应用。
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引用次数: 0
A Galerkin least-squares finite element method within deep neural networks for efficient simulation of generalized Newtonian flows in porous media 基于深度神经网络的Galerkin最小二乘有限元方法有效模拟多孔介质中广义牛顿流体流动
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-01-02 DOI: 10.1016/j.cam.2025.117331
Hsueh-Chen Lee , Hyesuk Lee
This study presents an integrated approach that combines the Galerkin least-squares (GLS) finite element method with deep neural networks (DNNs) to efficiently simulate generalized Newtonian flows of power-law fluids in porous media. The GLS method is employed to solve the two-dimensional nonlinear Brinkman equations, incorporating stabilization terms to address finite element space incompatibility by treating velocity, pressure, and stress as independent variables. Picard linearization and weak formulation ensure numerical stability and convergence, with the method achieving theoretical convergence rates in the L2-norm using low-order basis functions. To improve computational efficiency, a surrogate model based on DNNs is developed and validated for accuracy. The DNN is trained on GLS-generated data with a train/validation/test protocol, early stopping, and L2 regularization, thus ensuring an efficient accelerator for parameter studies requiring multiple simulations. By combining the numerical accuracy of the GLS method with the computational efficiency of DNNs, this hybrid approach enables rapid and scalable simulations of linearized Brinkman flows. The methodology is applied to pore-scale flow problems, demonstrating the DNN’s capability to replicate GLS solutions with low residual errors and significantly reduced computational costs. This study highlights the synergy between finite element methods and machine learning, offering a scalable and efficient solution for modeling complex fluid dynamics in porous media.
本文提出了一种将Galerkin最小二乘(GLS)有限元方法与深度神经网络(dnn)相结合的综合方法,以有效地模拟多孔介质中幂律流体的广义牛顿流动。采用GLS方法求解二维非线性Brinkman方程,以速度、压力和应力为自变量,引入稳定项解决有限元空间不相容问题。Picard线性化和弱公式保证了数值的稳定性和收敛性,该方法使用低阶基函数在l2范数上实现了理论收敛速率。为了提高计算效率,开发了基于深度神经网络的代理模型,并对其准确性进行了验证。DNN通过训练/验证/测试协议、早期停止和L2正则化在gls生成的数据上进行训练,从而确保了需要多次模拟的参数研究的高效加速器。通过将GLS方法的数值精度与dnn的计算效率相结合,这种混合方法能够快速和可扩展地模拟线性化Brinkman流。该方法应用于孔隙尺度流动问题,证明了DNN能够以低残余误差和显著降低计算成本的方式复制GLS解决方案。该研究强调了有限元方法和机器学习之间的协同作用,为多孔介质中复杂流体动力学的建模提供了可扩展和有效的解决方案。
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引用次数: 0
A C0 nonsymmetric interior penalty method for fourth order variational inequality 四阶变分不等式的C0非对称内罚方法
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2026-01-02 DOI: 10.1016/j.cam.2025.117334
Yanhua Mei , Jintao Cui , Yi Zhang , Fuzheng Gao
In this paper, we study a C0 nonsymmetric interior penalty method for the displacement obstacle problem of Kirchhoff plates on two and three dimensional general polygonal/polyhedral domains. We derive the error in an H2-like energy norm that converges in O(hα), where α is the index of elliptic regularity. Numerical experiments are performed to illustrate the theoretical results.
本文研究了二维和三维一般多边形/多面体区域上Kirchhoff板位移障碍问题的C0非对称内罚方法。我们导出了在O(hα)中收敛的类h2能量范数的误差,其中α是椭圆正则性的指标。数值实验验证了理论结果。
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引用次数: 0
Global polynomial synchronization of neutral-type Cohen-Grossberg neural networks with proportional delays and its application to image encryption 具有比例延迟的中性型Cohen-Grossberg神经网络的全局多项式同步及其在图像加密中的应用
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-31 DOI: 10.1016/j.cam.2025.117330
Wenyue Zheng, Liqun Zhou, Mou Zou
This paper investigates the global polynomial synchronization (GPS) problem of neutral-type Cohen-Grossberg neural networks (NTCGNNs) with proportional delays (PDs). First, a feedback controller is designed and a Lyapunov functional (LF) is constructed by introducing polynomial functions. We establish a delay-dependent GPS criterion. Second, building upon the feedback control framework, by introducing polynomial functions, we design an adaptive controller and construct a LF, resulting in a GPS criterion that does not require additional verification conditions. Introducing polynomial functions simultaneously in the controller and LF enables the determination of GPS without constraints, which is a key innovation of this paper. Finally, the theoretical results are validated through two numerical examples, and the synchronization control scheme is successfully applied to image encryption.
研究了具有比例延迟的中性型Cohen-Grossberg神经网络(ntcgnn)的全局多项式同步问题。首先设计了反馈控制器,并引入多项式函数构造了Lyapunov泛函(LF)。建立了时延相关的GPS准则。其次,在反馈控制框架的基础上,通过引入多项式函数,我们设计了一个自适应控制器并构造了一个LF,从而得到一个不需要额外验证条件的GPS准则。在控制器和LF中同时引入多项式函数,使得GPS的确定不受约束,这是本文的关键创新。最后,通过两个数值算例验证了理论结果,并将同步控制方案成功应用于图像加密。
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引用次数: 0
A parallel-implementable superlinearly-convergent OSWR method for delay-reaction-diffusion equations 延迟-反应-扩散方程的超线性收敛OSWR方法
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-31 DOI: 10.1016/j.cam.2025.117314
Xiaoyuan Xu , Chengjian Zhang
Overlapping Schwarz waveform relaxation (OSWR) methods are a class of highly effective numerical methods for solving evolution problems. Nevertheless, for the delay evolution problems, so far no superlinearly-convergent OSWR method has been presented. To make up for this deficiency, in the present paper, we suggest a parallel-implementable OSWR method for solving delay reaction-diffusion equations and prove that this method is superlinearly convergent. The provided numerical experiments further verify the superlinear convergence of the presented OSWR method and its comparability with the existing serial OSWR methods in computational efficiency.
重叠施瓦茨波形松弛法(OSWR)是一类求解演化问题的高效数值方法。然而,对于延迟演化问题,目前还没有超线性收敛的OSWR方法。为了弥补这一不足,本文提出了一种可并行实现的求解延迟反应扩散方程的OSWR方法,并证明了该方法是超线性收敛的。数值实验进一步验证了该方法的超线性收敛性,以及与现有串行OSWR方法在计算效率上的可比性。
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引用次数: 0
Sparse hyperparametric Itakura-Saito nonnegative matrix factorization via bi-level optimization 基于双水平优化的稀疏超参数Itakura-Saito非负矩阵分解
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-30 DOI: 10.1016/j.cam.2025.117316
Laura Selicato , Flavia Esposito , Andersen Ang , Nicoletta Del Buono , Rafał Zdunek
The selection of penalty hyperparameters is a critical aspect in Nonnegative Matrix Factorization (NMF), since these values control the trade-off between reconstruction accuracy and adherence to desired constraints. In this work, we focus on an NMF problem involving the Itakura-Saito (IS) divergence, which is particularly effective for extracting low spectral density components from spectrograms of mixed signals, and benefits from the introduction of sparsity constraints. We propose a new algorithm called SHINBO, which introduces a bi-level optimization framework to automatically and adaptively tune the row-dependent penalty hyperparameters, enhancing the ability of IS-NMF to isolate sparse, periodic signals in noisy environments. Experimental results demonstrate that SHINBO achieves accurate spectral decompositions and demonstrates superior performance in both synthetic and real-world applications. In the latter case, SHINBO is particularly useful for noninvasive vibration-based fault detection in rolling bearings, where the desired signal components often reside in high-frequency subbands but are obscured by stronger, spectrally broader noise. By addressing the critical issue of hyperparameter selection, SHINBO improves the state-of-the-art in signal recovery for complex, noise-dominated environments.
惩罚超参数的选择是非负矩阵分解(NMF)中的一个关键方面,因为这些值控制着重构精度和遵守期望约束之间的权衡。在这项工作中,我们专注于涉及Itakura-Saito (IS)散度的NMF问题,该问题对于从混合信号的频谱图中提取低谱密度分量特别有效,并受益于稀疏性约束的引入。我们提出了一种名为SHINBO的新算法,该算法引入了一个双级优化框架来自动自适应地调整行相关惩罚超参数,增强了IS-NMF在噪声环境中隔离稀疏周期性信号的能力。实验结果表明,SHINBO实现了精确的光谱分解,在合成和实际应用中都表现出优异的性能。在后一种情况下,SHINBO对于滚动轴承中基于非侵入性振动的故障检测特别有用,其中所需的信号成分通常位于高频子带中,但被更强、频谱更宽的噪声所掩盖。通过解决超参数选择的关键问题,SHINBO提高了复杂、噪声主导环境中信号恢复的最先进水平。
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引用次数: 0
A parametric family of polynomial wavelets for signal and image processing 用于信号和图像处理的参数多项式小波族
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-30 DOI: 10.1016/j.cam.2025.117317
Mariantonia Cotronei , Woula Themistoclakis , Marc Van Barel
This paper investigates the potential applications of a parametric family of polynomial wavelets that has been recently introduced starting from de la Vallée Poussin (VP) interpolation at Chebyshev nodes. Unlike classical wavelets, which are constructed on the real line, these VP wavelets are defined on a bounded interval, offering the advantage of handling boundaries naturally while maintaining computational efficiency. In addition, the structure of these wavelets enables the use of fast algorithms for decomposition and reconstruction. Furthermore, the flexibility offered by a free parameter allows a better control of localized singularities, such as edges in images. On the basis of previous theoretical foundations, we show the effectiveness of the VP wavelets for basic signal denoising and image compression, emphasizing their potential for more advanced signal and image processing tasks.
本文从Chebyshev节点的de la vall Poussin (VP)插值开始,研究了最近引入的参数多项式小波族的潜在应用。与在实线上构造的经典小波不同,这些VP小波是在有界区间上定义的,在保持计算效率的同时,提供了自然处理边界的优势。此外,这些小波的结构允许使用快速算法进行分解和重建。此外,自由参数提供的灵活性允许更好地控制局部奇点,例如图像中的边缘。在先前理论基础的基础上,我们展示了VP小波在基本信号去噪和图像压缩方面的有效性,强调了它们在更高级的信号和图像处理任务中的潜力。
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引用次数: 0
A linear programming framework and an improved backtracking strategy for multiple-gradient descent 多梯度下降的一种线性规划框架和改进的回溯策略
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-30 DOI: 10.1016/j.cam.2025.117324
Francesco Della Santa
This work introduces a method to compute descent directions common to two or more differentiable functions defined over a shared unconstrained domain. Building on this, an alternative Multiple-Gradient Descent procedure for Multi-Objective Optimization problems is proposed. The core of the approach consists of solving a relatively cheap Linear Programming (LP) problem, where the objective and constraints are constructed from the gradients of the functions involved. In particular, the LP formulation is designed such that, when a common descent direction does not exist, it still yields a direction that is perpendicular to all objectives’ gradients, if such a direction is available. Additionally, a tailored backtracking strategy is presented, enhancing the performance of Multiple-Gradient Descent methods, especially when paired with the proposed LP-based direction computation, by improving the exploration of the Pareto set and front. Theoretical analysis and experiments on standard benchmark problems are provided to evaluate the effectiveness of the proposed techniques.
本文介绍了一种计算在共享无约束域上定义的两个或多个可微函数的公共下降方向的方法。在此基础上,提出了一种多目标优化问题的多梯度下降算法。该方法的核心是解决一个相对便宜的线性规划(LP)问题,其中目标和约束是由所涉及的函数的梯度构造的。特别地,LP公式被设计成,当不存在一个共同的下降方向时,它仍然产生一个垂直于所有目标梯度的方向,如果这个方向是可用的。此外,提出了一种定制的回溯策略,通过改进对Pareto集和前沿的探索,提高了多重梯度下降方法的性能,特别是与所提出的基于lp的方向计算相结合时。对标准基准问题进行了理论分析和实验,以评估所提出技术的有效性。
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引用次数: 0
A regularization strategy for the backward problem for the fractional diffusion-wave equation with singular perturbation 具有奇异摄动的分数阶扩散-波动方程反向问题的正则化策略
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-30 DOI: 10.1016/j.cam.2025.117329
Jin Wen, Meng-Yao Zhou
This paper investigates the problem of simultaneously determining the initial value and initial velocity for the fractional diffusion-wave equation with singular perturbation, through the supplementary measurement data at two fixed time points. The paper derives the uniqueness of the solution to inverse problem by using the analytical and asymptotic characteristics of the Mittag-Leffler function, provided that the distance of these two time points is sufficiently small. In light of the problem’s ill-posedness, we adopt a boundary collocation method to solve this inverse problem, and use the Tikhonov regularization method combined with the GCV strategy. To demonstrate the efficiency and accuracy of our proposed method, we present several numerical examples in one-dimensional and two-dimensional cases.
本文利用两个固定时间点的补充测量数据,研究了具有奇异摄动的分数阶扩散-波动方程的初值和初速的同时确定问题。在两个时间点的距离足够小的条件下,利用Mittag-Leffler函数的解析性和渐近性,导出了逆问题解的唯一性。针对问题的病态性,采用边界搭配法求解该逆问题,并结合GCV策略使用Tikhonov正则化方法。为了证明该方法的有效性和准确性,我们给出了一维和二维情况下的几个数值算例。
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引用次数: 0
Weak galerkin methods for the Brinkman equations Brinkman方程的弱伽辽金方法
IF 2.6 2区 数学 Q1 MATHEMATICS, APPLIED Pub Date : 2025-12-29 DOI: 10.1016/j.cam.2025.117326
Chunmei Wang , Shangyou Zhang
This paper introduces a novel weak Galerkin (WG) finite element method for the numerical solution of the Brinkman equations. The Brinkman model, which seamlessly integrates characteristics of both the Stokes and Darcy equations, is employed to describe fluid flow in multiphysics contexts, particularly within heterogeneous porous media exhibiting spatially variable permeability. The proposed WG method offers a unified and robust approach capable of accurately capturing both Stokes- and Darcy-dominated regimes. A discrete inf-sup condition is established, and optimal-order error estimates are rigorously proven for the WG finite element solutions. Furthermore, a series of numerical experiments is performed to corroborate the theoretical analysis, demonstrating the method’s accuracy and stability in addressing the complexities inherent in the Brinkman equations.
本文介绍了一种求解Brinkman方程的弱Galerkin (WG)有限元方法。Brinkman模型无缝地整合了Stokes和Darcy方程的特征,用于描述多物理场环境下的流体流动,特别是在具有空间可变渗透率的非均质多孔介质中。所提出的WG方法提供了一种统一且健壮的方法,能够准确地捕获Stokes和darcy主导的政权。建立了离散耦合条件,并严格证明了WG有限元解的最优阶误差估计。此外,通过一系列数值实验验证了理论分析,证明了该方法在解决Brinkman方程固有复杂性方面的准确性和稳定性。
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引用次数: 0
期刊
Journal of Computational and Applied Mathematics
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