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A Liouville-type theorem for 3D stationary Navier–Stokes equations 三维平稳Navier-Stokes方程的liouville型定理
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1016/j.rinam.2025.100679
Zixuan Shen , Deyi Ma
In this paper, we establish a Liouville-type theorem for smooth solutions of the stationary Navier–Stokes equations under a growth condition on the Lebesgue norms. Based on this condition, we prove a lemma analogous to the Poincaré-type inequality in the curl sense, which serves as a key tool in proving our main result.
在Lebesgue范数的增长条件下,我们建立了平稳Navier-Stokes方程光滑解的liouville型定理。在此基础上,我们证明了旋度意义上的一个类似于poincar型不等式的引理,它是证明我们的主要结果的关键工具。
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引用次数: 0
A numerical framework based on piecewise Chebyshev cardinal functions for fractional integro-differential equations 基于分段切比雪夫基数函数的分数阶积分微分方程数值框架
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1016/j.rinam.2025.100682
S. Mansoori Aref , M.H. Heydari , M. Bayram
In this study, we develop an operational matrix technique to address a set of fractional nonlinear integro-differential equations with the Caputo–Hadamard derivative. We utilize a family of the piecewise Chebyshev cardinal functions as basis functions in this regard. Some formulas are introduced for calculating the classical and Hadamard fractional integrals of these functions. In the established strategy, the fractional expression is approximated utilizing these piecewise functions. By employing the aforementioned operational matrices and leveraging the cardinal property of the basis functions, we solve an algebraic system to obtain the solution. Convergence is both analytically demonstrated and confirmed through numerical experiments. Additionally, we compare the results obtained using this method with those derived from the hat functions method.
在这项研究中,我们发展了一种运算矩阵技术来解决一组分数阶非线性积分微分方程的Caputo-Hadamard导数。在这方面,我们利用一组分段切比雪夫基数函数作为基函数。介绍了这些函数的经典积分和阿达玛分数积分的计算公式。在所建立的策略中,分数表达式是利用这些分段函数逼近的。利用上述运算矩阵,利用基函数的基数性质,对一个代数系统进行求解。收敛性得到了解析论证和数值实验的证实。此外,我们还将用这种方法得到的结果与帽函数方法得到的结果进行了比较。
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引用次数: 0
Screening effects in Gaussian random fields under generalized spectral conditions 广义谱条件下高斯随机场的筛选效应
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1016/j.rinam.2025.100681
Mohammad Meysami , Ali Lotfi
The screening effect is a central idea in spatial prediction: once nearby observations are used, distant ones add little. While Stein’s classical results explain this effect under strong spectral conditions, many models used in practice fall outside those assumptions. In this paper, we extend Stein’s theory to a broader class of Gaussian random fields. We replace strict regular variation by more flexible O-regular variation, resolve the critical borderline case where the spectral exponent equals the dimension, and derive explicit convergence rates for prediction error. Our analysis also shows that screening is robust to mild nonstationarity and anisotropy, and it applies to irregular sampling designs such as Delone sets. To illustrate these results, we provide examples with Matérn, generalized Cauchy, and anisotropic models, along with numerical experiments confirming the theory. These findings clarify when local kriging can safely replace global prediction, and they provide a solid foundation for scalable methods such as covariance tapering and Vecchia approximations.
筛选效应是空间预测的核心思想:一旦使用了近距离的观测结果,远距离的观测结果就没有什么帮助了。虽然斯坦的经典结果在强光谱条件下解释了这种效应,但在实践中使用的许多模型都超出了这些假设。在本文中,我们将Stein的理论推广到更广泛的高斯随机场。我们用更灵活的o规则变化代替严格的规则变化,解决了谱指数等于维数的临界边界情况,并推导出预测误差的显式收敛率。我们的分析还表明,筛选对轻度非平稳性和各向异性具有鲁棒性,并且适用于不规则采样设计,如Delone集。为了说明这些结果,我们提供了mat、广义柯西和各向异性模型的例子,以及证实该理论的数值实验。这些发现阐明了局部克里格何时可以安全地取代全局预测,并为协方差渐缩和维奇亚近似等可扩展方法提供了坚实的基础。
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引用次数: 0
Optimal second order covariant derivatives on associated bundles — Application to color image restoration 关联束的最优二阶协变导数。在彩色图像恢复中的应用
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1016/j.rinam.2025.100680
Thomas Batard
This paper deals with the application of a geometric setting widely employed in theoretical physics, namely the fiber bundles, to color image restoration. The key idea of this approach is to model an image as a function on a principal bundle satisfying an equivariance property with respect to the action of a Lie group acting on its pixel values, and which can model the lighting changes in a scene. In this context, a natural tool for the differentiation of an image is by means of a covariant derivative. In previous works, optimal covariant derivatives have been constructed as solutions of a variational model consisting of the minimization of the L2 norm of the covariant derivative of the image, and applied to various tasks in color image restoration through the extension of the Total Variation regularizer to vector bundles. The aim of this paper is to extend these works by constructing optimal second order covariant derivatives as solutions of the minimization of the norm of the second order covariant derivative of the image. Experiments on deblurring and super-resolution corroborate the relevance of the proposed model for color image restoration. More generally, this paper validates the use of the geometric setting of fiber bundles in imaging sciences.
本文讨论了理论物理中广泛使用的几何设置,即光纤束在彩色图像恢复中的应用。这种方法的关键思想是将图像建模为一个主束上的函数,该函数满足李群作用于其像素值的等方差属性,并且可以模拟场景中的照明变化。在这种情况下,对图像进行微分的自然工具是借助协变导数。在以前的工作中,最优协变导数已被构造为由图像协变导数的L2范数的最小化组成的变分模型的解,并通过将总变分正则器扩展到向量束,将其应用于彩色图像恢复的各种任务。本文的目的是通过构造最优二阶协变导数作为图像二阶协变导数范数最小化的解来扩展这些工作。去模糊和超分辨率实验验证了该模型在彩色图像恢复中的适用性。更一般地说,本文验证了纤维束几何设置在成像科学中的应用。
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引用次数: 0
A quantum graph FFT with applications to partial differential equations on networks 量子图FFT及其在网络偏微分方程中的应用
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2026-01-06 DOI: 10.1016/j.rinam.2025.100670
Robert Carlson
The Fast Fourier Transform is extended to functions on finite graphs whose edges are identified with intervals of finite length. Spectral and pseudospectral methods are developed to solve a wide variety of time dependent partial differential equations on domains which are modeled as networks of one dimensional segments joined at nodes.
将快速傅里叶变换推广到有限图上的函数,这些图的边用有限长区间标识。谱和伪谱方法用于求解各种时域相关的偏微分方程,这些偏微分方程被建模为在节点处连接的一维段网络。
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引用次数: 0
A hybrid numerical method for multi-domain wave propagation problems 多域波传播问题的混合数值方法
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2025-12-17 DOI: 10.1016/j.rinam.2025.100678
Zihui Yan , Xiangran Zheng , Wenzhen Qu , Sheng-Dong Zhao
This study introduces a hybrid numerical methodology designed to address multi-domain wave propagation problems. The temporal discretization is achieved using the Houbolt scheme, a finite-difference-based approach known for its robust stability in time-dependent simulations. Spatially, the computational domain is partitioned into subdomains via a domain decomposition strategy, with continuity and equilibrium constraints imposed along the interfaces to ensure physical fidelity. Within each subdomain, the meshless generalized finite difference method (GFDM) is employed, thereby avoiding the complexity of mesh generation. Through the integration of Taylor series expansion and moving least squares (MLS) approximation, explicit formulations of partial derivatives are constructed. Numerical experiments confirm that the proposed hybrid method provides high accuracy and stability in simulating multi-domain wave propagation phenomena.
本文介绍了一种混合数值方法,旨在解决多域波传播问题。时间离散化是使用Houbolt方案实现的,这是一种基于有限差分的方法,以其在依赖时间的模拟中的鲁棒稳定性而闻名。在空间上,通过域分解策略将计算域划分为子域,并沿界面施加连续性和平衡约束以确保物理保真度。在每个子域中采用无网格广义有限差分法(GFDM),避免了网格生成的复杂性。通过泰勒级数展开和移动最小二乘逼近的积分,构造了偏导数的显式表达式。数值实验结果表明,该方法在模拟多域波传播现象时具有较高的精度和稳定性。
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引用次数: 0
A hybrid MPWENO scheme with enhanced accuracy and robustness for the compressible Euler equations 一种提高精度和鲁棒性的混合MPWENO可压缩欧拉方程解
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2025-12-17 DOI: 10.1016/j.rinam.2025.100674
Yalin Tang , Mingjun Li , Shujiang Tang
In this study, we develop a hybrid high-order monotonicity-preserving Weighted Essentially Non-Oscillatory (MPWENO) finite difference discretization for the compressible Euler equations. The key innovation of this scheme lies in optimizing the numerical flux through the mixed smooth indicator to reduce the numerical oscillations caused by scheme conversion, and adjusting the reference value to modify the MP limiter, thereby enabling the scheme to achieve the required numerical accuracy while maintaining monotonicity. The novelty of this work lies in systematically adjusting the numerical fluxes by using the mixed smooth indicator to distinguish between discontinuities and extrema and improving the accuracy of the reference value to change the MP limiter, which is different from other MP schemes. The proposed method improves the accuracy at the extreme points, exhibits outstanding robustness and excellent resolution, making it particularly suitable for solving complex problems in compressible Euler equations. Moreover, it is easy to implement and applicable to multi-dimensional problems, with significant practical advantages. Numerical results show that this method has high accuracy, strong robustness, and high resolution. These findings highlight the effectiveness and reliability of this method in handling complex compressible flow simulations.
本文研究了可压缩欧拉方程的混合高阶保持单调性加权本质非振荡有限差分离散方法。该方案的关键创新之处在于通过混合光滑指示器优化数值通量,以减少方案转换引起的数值振荡,并通过调整参考值来修改MP限幅器,从而使方案在保持单调性的同时达到所需的数值精度。本工作的新颖之处在于,不同于其他多普勒方案,利用混合光滑指示器区分不连续点和极值点,系统地调整数值通量,提高参考值的精度,从而改变多普勒限制器。该方法提高了极值点的精度,具有较强的鲁棒性和较好的分辨率,特别适用于求解可压缩欧拉方程中的复杂问题。该方法易于实现,适用于多维问题,具有显著的实用优势。数值结果表明,该方法精度高、鲁棒性强、分辨率高。这些发现突出了该方法在处理复杂可压缩流动模拟中的有效性和可靠性。
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引用次数: 0
General conservative sixth- and eighth-order compact finite difference schemes for the N-coupled Schrödinger-Boussinesq equations n -耦合Schrödinger-Boussinesq方程的一般保守六阶和八阶紧致有限差分格式
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2025-12-06 DOI: 10.1016/j.rinam.2025.100677
Jiadong Qiu , Xiang Liu , Feng Liao
In this paper, general conservative sixth- and eighth-order compact finite difference schemes are presented to solve the N-coupled nonlinear Schrödinger-Boussinesq equations numerically. The existence of the difference solution is proved by fixed-point theorem. By utilizing the discrete energy methods, the proposed difference schemes are proved to be unconditionally convergent at the order O(τ2+h8) with mesh-size h and time step τ in the discrete L-norm. By using the Yoshida’s composition method, we improve the scheme (3.1)-(3.3) with a group of given time-step increments repeatedly and then obtain a temporal fourth-order difference scheme. Numerical experiments confirm the theoretical results and verify the accuracy and efficiency of our method.
本文给出了n -耦合非线性Schrödinger-Boussinesq方程的一般保守六阶和八阶紧致有限差分格式。用不动点定理证明了差分解的存在性。利用离散能量法,证明了所提差分格式在离散L∞范数下,网格大小为h,时间步长为τ,在O(τ2+h8)阶上无条件收敛。利用Yoshida的复合方法,我们用一组给定的时间步长增量重复改进式(3.1)-(3.3),得到一个时间四阶差分格式。数值实验验证了理论结果,验证了方法的准确性和有效性。
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引用次数: 0
A parameterized Schur complement preconditioner for linear system arising from additive HQ image restoration 加性HQ图像恢复线性系统的参数化Schur补预条件
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2025-11-01 DOI: 10.1016/j.rinam.2025.100667
Peipei Zhao , Pengyu Zhang
Image restoration is to estimate the clean image from the recorded image, it is a highly ill-posed inverse problem. Regularization method is an important approach for solving such problem, which can usually be achieved by minimizing a cost function consisting of a data-fidelity term and a regularization term. In this paper, we consider the additive half-quadratic (HQ) regularized method for image restoration problem, and utilize the Newton method to solve the resulting minimization problem. At each Newton iteration step, a system of linear equations with symmetric positive definite coefficient matrix arises. In order to solve the linear system efficiently, we design a parameterized approximation matrix of the Schur complement inverse matrix, and construct a block preconditioner with parameter correspondingly, according to the block triangular factorization of coefficient matrix and the form of its Schur complement, then the preconditioned conjugate gradient (PCG) method is applied to solve the linear system of equations. Spectral analyses of the preconditioned matrix are also given, numerical experimental results demonstrate the effectiveness of the proposed parameterized preconditioner for solving linear system arising from additive HQ image restoration problem.
图像恢复就是从记录的图像中估计出干净的图像,是一个高度不适定的逆问题。正则化方法是解决这类问题的重要方法,通常可以通过最小化由数据保真度项和正则化项组成的代价函数来实现。本文考虑了图像恢复问题的加性半二次正则化方法,并利用牛顿法求解得到的最小化问题。在牛顿迭代的每一步,都会产生一个具有对称正定系数矩阵的线性方程组。为了有效求解线性方程组,根据系数矩阵的分块三角分解及其Schur补的形式,设计了Schur补逆矩阵的参数化近似矩阵,构造了相应的带参数的分块预调节器,然后应用预条件共轭梯度(PCG)法求解线性方程组。对预条件矩阵进行了光谱分析,数值实验结果表明,所提出的参数化预条件对于线性系统的加性HQ图像恢复问题是有效的。
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引用次数: 0
Lanczos algorithm explained in statistics 统计学解释Lanczos算法
IF 1.3 Q2 MATHEMATICS, APPLIED Pub Date : 2025-11-01 DOI: 10.1016/j.rinam.2025.100666
Qiang Niu , Mianmian Chen , Jinheng Wu
The Lanczos algorithm is a well-known three-term recurrence that can be used to generate an orthogonal basis for a Krylov subspace derived by a symmetric matrix. In the paper, we present a statistical interpretation of the entries of the tridiagonal matrix generated by the Lanczos process with a diagonal matrix X and an initial vector e. We show that the entries on the main diagonal line can be interpreted as weighted mean and the entries on the super-diagonal line can be understood as weighted sum of variance. Besides, a recurrence for producing the entries on the off-diagonal entries of the tridiagonal matrix is discovered, which leads to a new implementation of the Lanczos process. Finally, numerical examples are provided to investigate the preservation of orthogonality and efficiency in data fitting.
Lanczos算法是一种著名的三项递归算法,可以用来生成由对称矩阵导出的Krylov子空间的正交基。本文用一个对角矩阵X和一个初始向量e对Lanczos过程生成的三对角矩阵的条目进行了统计解释。我们证明主对角线上的条目可以解释为加权均值,超对角线上的条目可以理解为加权方差和。此外,还发现了在三对角矩阵的非对角项上产生项的递归式,从而给出了Lanczos过程的一种新的实现方法。最后,给出了数值算例来研究数据拟合中保持正交性和效率的问题。
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引用次数: 0
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Results in Applied Mathematics
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