Pub Date : 2026-08-01Epub Date: 2026-01-28DOI: 10.1016/j.matcom.2026.01.029
Walid Remili , Samad Noeiaghdam
This paper introduces a high-order numerical method for the solution of nonlinear Volterra–Hammerstein integral equations (NVHIEs) with smooth and weakly singular kernels, based on the collocation approach. The proposed method employs a collocation scheme with shifted Chebyshev polynomials (SCPs), combined with an appropriate variable transformation, to reduce the integral equation to a nonlinear algebraic system. We rigorously analyze the convergence properties of the collocation method, establishing its theoretical validity and proving a specific convergence rate of , which highlights the rigor and efficiency of the approach. To ensure reliable error control and stability, we integrate the CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library, providing a unified framework that identifies numerical instabilities (self-validation, mathematical, branching, and intrinsic) while also determining the optimal step size, optimal approximation, and optimal error. Several numerical examples are presented and compared with existing methods to illustrate the enhanced efficiency and accuracy of our approach.
本文介绍了一种基于配点法求解光滑弱奇异核非线性Volterra-Hammerstein积分方程的高阶数值方法。该方法采用平移切比雪夫多项式(SCPs)搭配方案,结合适当的变量变换,将积分方程简化为非线性代数系统。我们严格分析了该方法的收敛性,建立了该方法的理论有效性,并证明了其特定的收敛速度为0 (N3/4−m),从而突出了该方法的严谨性和有效性。为了确保可靠的误差控制和稳定性,我们集成了CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs)方法和CADNA(精度控制和数值应用调试)库,提供了一个统一的框架,可以识别数值不稳定性(自我验证、数学、分支和内在),同时确定最佳步长、最佳近似和最佳误差。给出了几个数值算例,并与现有方法进行了比较,以说明本文方法提高了效率和精度。
{"title":"Shifted Chebyshev collocation with CESTAC-CADNA-based instability detection for nonlinear Volterra–Hammerstein integral equations","authors":"Walid Remili , Samad Noeiaghdam","doi":"10.1016/j.matcom.2026.01.029","DOIUrl":"10.1016/j.matcom.2026.01.029","url":null,"abstract":"<div><div>This paper introduces a high-order numerical method for the solution of nonlinear Volterra–Hammerstein integral equations (NVHIEs) with smooth and weakly singular kernels, based on the collocation approach. The proposed method employs a collocation scheme with shifted Chebyshev polynomials (SCPs), combined with an appropriate variable transformation, to reduce the integral equation to a nonlinear algebraic system. We rigorously analyze the convergence properties of the collocation method, establishing its theoretical validity and proving a specific convergence rate of <span><math><mrow><mi>O</mi><mrow><mo>(</mo><msup><mrow><mi>N</mi></mrow><mrow><mn>3</mn><mo>/</mo><mn>4</mn><mo>−</mo><mi>m</mi></mrow></msup><mo>)</mo></mrow></mrow></math></span>, which highlights the rigor and efficiency of the approach. To ensure reliable error control and stability, we integrate the CESTAC (Contrôle et Estimation Stochastique des Arrondis de Calculs) method and the CADNA (Control of Accuracy and Debugging for Numerical Applications) library, providing a unified framework that identifies numerical instabilities (self-validation, mathematical, branching, and intrinsic) while also determining the optimal step size, optimal approximation, and optimal error. Several numerical examples are presented and compared with existing methods to illustrate the enhanced efficiency and accuracy of our approach.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 60-77"},"PeriodicalIF":4.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-08-01Epub Date: 2026-01-24DOI: 10.1016/j.matcom.2026.01.027
Vikash Sharma, Vineet Kumar Singh
In this manuscript, we investigate various properties of the Generalized time fractional derivative (GTFD). We establish several regularity results and derive bounds in specific spaces like that characterize the behavior of the GTFD operator. Furthermore, we propose an efficient hybrid computational approximation to approximate the GTFD of order , applicable to smooth and non-smooth solutions. This approximation is based on a Newton interpolation polynomial of arbitrary finite degree. The role of scale and weight functions in influencing the local truncation error and convergence order is thoroughly analyzed, with numerical experiments providing validation of these theoretical insights. The proposed approximation is further utilized to construct a computational scheme for solving the general time fractional diffusion equation (GTFDE), for which we rigorously establish uniqueness and convergence, while stability is proven specifically for linear interpolation. Numerical examples are utilized to verify that our scheme is more efficient compared to the existing schemes (Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013). Without loss of generality, numerical results are presented for linear and quadratic interpolation, confirming the approximation’s accuracy and consistency with theoretical predictions.
本文研究了广义时间分数阶导数(GTFD)的各种性质。我们建立了几个正则性结果,并在C1,W1,1等特定空间中推导了表征GTFD算子行为的界。此外,我们提出了一种有效的混合计算近似来近似阶α∈(0,1)的GTFD,适用于光滑和非光滑解。这种近似是基于任意有限次的牛顿插值多项式。深入分析了尺度函数和权函数对局部截断误差和收敛阶的影响,并通过数值实验验证了这些理论见解。进一步利用所提出的近似构造了求解一般时间分数扩散方程(GTFDE)的计算格式,并严格建立了该格式的唯一性和收敛性,同时证明了该格式在线性插值下的稳定性。数值算例验证了我们的方案比现有方案更高效(Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013)。在不丧失一般性的情况下,给出了线性和二次插值的数值结果,证实了近似的准确性和与理论预测的一致性。
{"title":"Approximation of generalized time fractional derivatives: Error analysis via scale and weight functions","authors":"Vikash Sharma, Vineet Kumar Singh","doi":"10.1016/j.matcom.2026.01.027","DOIUrl":"10.1016/j.matcom.2026.01.027","url":null,"abstract":"<div><div>In this manuscript, we investigate various properties of the Generalized time fractional derivative (GTFD). We establish several regularity results and derive bounds in specific spaces like <span><math><mrow><msup><mrow><mi>C</mi></mrow><mrow><mn>1</mn></mrow></msup><mo>,</mo><msup><mrow><mi>W</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>1</mn></mrow></msup></mrow></math></span> that characterize the behavior of the GTFD operator. Furthermore, we propose an efficient hybrid computational approximation to approximate the GTFD of order <span><math><mrow><mi>α</mi><mo>∈</mo><mrow><mo>(</mo><mn>0</mn><mo>,</mo><mn>1</mn><mo>)</mo></mrow></mrow></math></span>, applicable to smooth and non-smooth solutions. This approximation is based on a Newton interpolation polynomial of arbitrary finite degree. The role of scale and weight functions in influencing the local truncation error and convergence order is thoroughly analyzed, with numerical experiments providing validation of these theoretical insights. The proposed approximation is further utilized to construct a computational scheme for solving the general time fractional diffusion equation (GTFDE), for which we rigorously establish uniqueness and convergence, while stability is proven specifically for linear interpolation. Numerical examples are utilized to verify that our scheme is more efficient compared to the existing schemes (Stynes et al., 2017, Z. wang, 2025 and Xu et al., 2013). Without loss of generality, numerical results are presented for linear and quadratic interpolation, confirming the approximation’s accuracy and consistency with theoretical predictions.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 1-24"},"PeriodicalIF":4.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-08-01Epub Date: 2026-01-23DOI: 10.1016/j.matcom.2026.01.028
Xiaoquan Kong , Ruizhi Yang
This study focuses on the Lymantria dispar-Great tit ecosystem, constructing a Filippov model with double Allee effects and proposing an integrated control strategy based on two thresholds for both pest density and natural enemy abundance. Through stability analysis of equilibria and sliding mode dynamics, the study reveals the existence of multiple sliding segments and pseudo-equilibria in the system, which can induce rich sliding bifurcation behaviors. Further investigation uncovers complex dynamical patterns under different threshold conditions, including sliding bifurcations as well as local and global bifurcations. Partial Rank Correlation Coefficient based global sensitivity analysis identifies key parameters influencing the system dynamics. The research demonstrates that appropriate setting of these two thresholds is crucial for achieving sustainable control of Lymantria dispar, while the synergistic effect of biological control and natural enemy release is essential for maintaining ecological balance.
本文以Lymantria - great tit生态系统为研究对象,构建了具有双Allee效应的Filippov模型,提出了基于害虫密度和天敌丰度两个阈值的综合防治策略。通过平衡态和滑模动力学稳定性分析,揭示了系统中存在多个滑动段和伪平衡态,从而引发丰富的滑动分岔行为。进一步的研究揭示了不同阈值条件下复杂的动力学模式,包括滑动分岔以及局部和全局分岔。基于偏秩相关系数的全局敏感性分析识别出影响系统动力学的关键参数。研究表明,合理设置这两个阈值对于实现野毒的可持续控制至关重要,而生物防治与天敌释放的协同效应对于维持生态平衡至关重要。
{"title":"Dynamics analysis of a Filippov Lymantria dispar-Great tit model with double Allee effects and two-thresholds control","authors":"Xiaoquan Kong , Ruizhi Yang","doi":"10.1016/j.matcom.2026.01.028","DOIUrl":"10.1016/j.matcom.2026.01.028","url":null,"abstract":"<div><div>This study focuses on the Lymantria dispar-Great tit ecosystem, constructing a Filippov model with double Allee effects and proposing an integrated control strategy based on two thresholds for both pest density and natural enemy abundance. Through stability analysis of equilibria and sliding mode dynamics, the study reveals the existence of multiple sliding segments and pseudo-equilibria in the system, which can induce rich sliding bifurcation behaviors. Further investigation uncovers complex dynamical patterns under different threshold conditions, including sliding bifurcations as well as local and global bifurcations. Partial Rank Correlation Coefficient based global sensitivity analysis identifies key parameters influencing the system dynamics. The research demonstrates that appropriate setting of these two thresholds is crucial for achieving sustainable control of Lymantria dispar, while the synergistic effect of biological control and natural enemy release is essential for maintaining ecological balance.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 25-43"},"PeriodicalIF":4.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146057484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-08-01Epub Date: 2026-01-16DOI: 10.1016/j.matcom.2026.01.010
Amine Mebarki, Moussa Labbadi, Mohamed Zerrougui
Modern robotic applications demand precise trajectory tracking, which is particularly challenging due to the nonlinear dynamics, model uncertainties, and external disturbances inherent in robotic manipulators. Robust control strategies, such as Sliding Mode Control (SMC), have proven effective in addressing these challenges. Advanced variants, including finite-time and fixed-time SMC, offer the added advantage of ensuring stabilization within a predefined time frame. This paper proposes various strategies for the Franka robot, ensuring global fixed-time convergence of the closed-loop system with a singularity-free design and the settling time estimation is independent of initial conditions. A non-singular terminal sliding surface is utilized to achieve precise trajectory tracking, enhanced robustness to external disturbances, and simplified implementation. The effectiveness of the proposed methods is validated through realistic simulations of the Franka robot.
{"title":"Robust non-singular fixed-time sliding mode control for robot manipulators: Franka robot arm","authors":"Amine Mebarki, Moussa Labbadi, Mohamed Zerrougui","doi":"10.1016/j.matcom.2026.01.010","DOIUrl":"10.1016/j.matcom.2026.01.010","url":null,"abstract":"<div><div>Modern robotic applications demand precise trajectory tracking, which is particularly challenging due to the nonlinear dynamics, model uncertainties, and external disturbances inherent in robotic manipulators. Robust control strategies, such as Sliding Mode Control (SMC), have proven effective in addressing these challenges. Advanced variants, including finite-time and fixed-time SMC, offer the added advantage of ensuring stabilization within a predefined time frame. This paper proposes various strategies for the Franka robot, ensuring global fixed-time convergence of the closed-loop system with a singularity-free design and the settling time estimation is independent of initial conditions. A non-singular terminal sliding surface is utilized to achieve precise trajectory tracking, enhanced robustness to external disturbances, and simplified implementation. The effectiveness of the proposed methods is validated through realistic simulations of the Franka robot.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"246 ","pages":"Pages 44-59"},"PeriodicalIF":4.4,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146081413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-10DOI: 10.1016/j.matcom.2026.01.007
Jinyuan Zhang , Yuechao Ma
This article focuses on the pinning synchronization issue for Takagi–Sugeno (T–S) fuzzy complex dynamical networks (CDNs) under critical-data-targeted denial-of-service (DoS) attacks. Firstly, a novel critical-data-targeted DoS attack method is considered for the attacker to enhance the destructiveness of the attack against various nodes. Contrasting with most existing DoS attack models, this attack scheme can selectively attack critical data, allowing the attacker to cause relatively large damage to system performance. Secondly, we establish a new pinning synchronization control model for T–S fuzzy CDNs with random coupling delays. It can describe the actual world more accurately compared with the general model of CDNs. And the issue of asynchronous premise variables is solved. Furthermore, a new secure synchronization criterion is presented by leveraging the appropriate Lyapunov–Krasovskii function to realize the performance of the system against critical-data-targeted DoS attacks. Finally, three examples are offered to confirm the efficacy of the suggested results.
{"title":"Secure synchronization of T–S fuzzy complex dynamical networks under critical-data-targeted DoS attacks","authors":"Jinyuan Zhang , Yuechao Ma","doi":"10.1016/j.matcom.2026.01.007","DOIUrl":"10.1016/j.matcom.2026.01.007","url":null,"abstract":"<div><div>This article focuses on the pinning synchronization issue for Takagi–Sugeno (T–S) fuzzy complex dynamical networks (CDNs) under critical-data-targeted denial-of-service (DoS) attacks. Firstly, a novel critical-data-targeted DoS attack method is considered for the attacker to enhance the destructiveness of the attack against various nodes. Contrasting with most existing DoS attack models, this attack scheme can selectively attack critical data, allowing the attacker to cause relatively large damage to system performance. Secondly, we establish a new pinning synchronization control model for T–S fuzzy CDNs with random coupling delays. It can describe the actual world more accurately compared with the general model of CDNs. And the issue of asynchronous premise variables is solved. Furthermore, a new secure synchronization criterion is presented by leveraging the appropriate Lyapunov–Krasovskii function to realize the <span><math><msub><mrow><mi>H</mi></mrow><mrow><mi>∞</mi></mrow></msub></math></span> performance of the system against critical-data-targeted DoS attacks. Finally, three examples are offered to confirm the efficacy of the suggested results.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 95-113"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145980217","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-17DOI: 10.1016/j.matcom.2026.01.015
B. Takacs
In this paper, nonstandard multistep methods are considered. It is shown that under some (sufficient and necessary) conditions, these methods attain the same order as their standard counterpart — to prove this statement, a nonstandard version of Taylor’s series is constructed. The preservation of some qualitative properties (boundedness, the linear combination of the components, and a property similar to monotonicity) is also proven for all step sizes. The methods are applied to a one-dimensional equation and a system of equations, in which the numerical experiments confirm the theoretical results.
{"title":"An insight on some properties of high order nonstandard linear multistep methods","authors":"B. Takacs","doi":"10.1016/j.matcom.2026.01.015","DOIUrl":"10.1016/j.matcom.2026.01.015","url":null,"abstract":"<div><div>In this paper, nonstandard multistep methods are considered. It is shown that under some (sufficient and necessary) conditions, these methods attain the same order as their standard counterpart — to prove this statement, a nonstandard version of Taylor’s series is constructed. The preservation of some qualitative properties (boundedness, the linear combination of the components, and a property similar to monotonicity) is also proven for all step sizes. The methods are applied to a one-dimensional equation and a system of equations, in which the numerical experiments confirm the theoretical results.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 337-365"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-06DOI: 10.1016/j.matcom.2026.01.003
Hiroyuki Sato , Yuya Yamakawa , Kensuke Aihara
For optimization problems on Riemannian manifolds, many types of globally convergent algorithms have been proposed, and they are often equipped with the Riemannian version of the Armijo line search for global convergence. Such existing methods need to compute the value of a retraction mapping regarding the search direction several times at each iteration; this may result in high computational costs, particularly if computing the value of the retraction is expensive. To address this issue, this study focuses on embedded Riemannian submanifolds of the Euclidean spaces and proposes a novel Riemannian line search that achieves lower computational cost by incorporating a new strategy that computes the retraction only when inevitable. A class of Riemannian optimization algorithms, including the steepest descent and Newton methods, with the new line search strategy is proposed and proved to be globally convergent. Furthermore, numerical experiments on solving optimization problems on several types of embedded Riemannian submanifolds illustrate that the proposed methods are superior to the standard Riemannian Armijo line search-based methods.
{"title":"Modified Armijo line search in optimization on Riemannian submanifolds with reduced computational cost","authors":"Hiroyuki Sato , Yuya Yamakawa , Kensuke Aihara","doi":"10.1016/j.matcom.2026.01.003","DOIUrl":"10.1016/j.matcom.2026.01.003","url":null,"abstract":"<div><div>For optimization problems on Riemannian manifolds, many types of globally convergent algorithms have been proposed, and they are often equipped with the Riemannian version of the Armijo line search for global convergence. Such existing methods need to compute the value of a retraction mapping regarding the search direction several times at each iteration; this may result in high computational costs, particularly if computing the value of the retraction is expensive. To address this issue, this study focuses on embedded Riemannian submanifolds of the Euclidean spaces and proposes a novel Riemannian line search that achieves lower computational cost by incorporating a new strategy that computes the retraction only when inevitable. A class of Riemannian optimization algorithms, including the steepest descent and Newton methods, with the new line search strategy is proposed and proved to be globally convergent. Furthermore, numerical experiments on solving optimization problems on several types of embedded Riemannian submanifolds illustrate that the proposed methods are superior to the standard Riemannian Armijo line search-based methods.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 260-274"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038828","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-16DOI: 10.1016/j.matcom.2026.01.017
Hongli Yang , Xianyang Zeng , Hao Yu
For Maxwell’s equations for isotropic homogeneous media in a cubic domain, there have been few methods that can solve almost all problems under various boundary conditions in source field since the boundary conditions and the sources are diverse, by now. Fortunately, in this paper, we succeeded in giving a unified class of methods (called S-ERKN methods) that solve problems under a wide range of boundary conditions in source field. At first, we gave a detailed study on the spatial discretization to have a so-called semi-discrete system. Here we concluded that the boundary conditions had an unsurprising impact on the differentiation matrix (denoted as in this paper) but had an unexpected effect on the perturbation term (denoted as in this paper) of the semi-discrete system. Secondly, we chose the ERKN (Extended Runge–Kutta Nystrom) methods as the temporal solver to improve the temporal order which is normally limited to 2 in many traditional numerical solutions. To make the S-ERKN method (obtained by the spatial and temporal discretization shown above) easy to code at low cost, we studied the fast calculation of the matrix vector product , which is the basic computational unit of the method. In this paper, we also performed the divergence analysis of the methods. The numerical experiments illuminate that the method can be explicit, highly accurate, divergence-free in numerical terms, and of good long-term behavior.
{"title":"S-ERKN methods solving Maxwell’s equations in source field under wide range of boundary conditions","authors":"Hongli Yang , Xianyang Zeng , Hao Yu","doi":"10.1016/j.matcom.2026.01.017","DOIUrl":"10.1016/j.matcom.2026.01.017","url":null,"abstract":"<div><div>For Maxwell’s equations for isotropic homogeneous media in a cubic domain, there have been few methods that can solve almost all problems under various boundary conditions in source field since the boundary conditions and the sources are diverse, by now. Fortunately, in this paper, we succeeded in giving a unified class of methods (called S-ERKN methods) that solve problems under a wide range of boundary conditions in source field. At first, we gave a detailed study on the spatial discretization to have a so-called semi-discrete system. Here we concluded that the boundary conditions had an unsurprising impact on the differentiation matrix (denoted as <span><math><msub><mrow><mi>L</mi></mrow><mrow><mi>U</mi></mrow></msub></math></span> in this paper) but had an unexpected effect on the perturbation term (denoted as <span><math><msub><mrow><mover><mrow><mi>F</mi></mrow><mrow><mo>̃</mo></mrow></mover></mrow><mrow><mi>U</mi></mrow></msub></math></span> in this paper) of the semi-discrete system. Secondly, we chose the ERKN (Extended Runge–Kutta Nystrom) methods as the temporal solver to improve the temporal order which is normally limited to 2 in many traditional numerical solutions. To make the S-ERKN method (obtained by the spatial and temporal discretization shown above) easy to code at low cost, we studied the fast calculation of the matrix vector product <span><math><mrow><msub><mrow><mi>L</mi></mrow><mrow><mi>U</mi></mrow></msub><mi>V</mi></mrow></math></span>, which is the basic computational unit of the method. In this paper, we also performed the divergence analysis of the methods. The numerical experiments illuminate that the method can be explicit, highly accurate, divergence-free in numerical terms, and of good long-term behavior.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 143-175"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146038827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we propose and analyze a finite element coupled multiscale finite element method (FEM-MsFEM) for an interface-coupled parabolic problem. The problem involves a coefficient with multiscale characteristics in one region and in the other region without such feature. Our algorithm consists of two main steps: first, solving for the multiscale basis functions in the multiscale region via parallel computation; and second, decoupling the interface-coupled parabolic problem using a data-passing partitioned scheme. This approach allows for the problem to be solved on relatively coarse grids, thereby reducing computational costs. Under suitable assumptions for the multiscale coefficient, we establish the unconditional stability and provide error estimates for the algorithm. The effectiveness of our method is demonstrated through several numerical experiments.
{"title":"FEM-MsFEM for an interface-coupled parabolic problem","authors":"Jiaping Yu , Wenhan Zhang , Ren Zhao , Haibiao Zheng","doi":"10.1016/j.matcom.2026.01.023","DOIUrl":"10.1016/j.matcom.2026.01.023","url":null,"abstract":"<div><div>In this paper, we propose and analyze a finite element coupled multiscale finite element method (FEM-MsFEM) for an interface-coupled parabolic problem. The problem involves a coefficient with multiscale characteristics in one region and in the other region without such feature. Our algorithm consists of two main steps: first, solving for the multiscale basis functions in the multiscale region via parallel computation; and second, decoupling the interface-coupled parabolic problem using a data-passing partitioned scheme. This approach allows for the problem to be solved on relatively coarse grids, thereby reducing computational costs. Under suitable assumptions for the multiscale coefficient, we establish the unconditional stability and provide error estimates for the algorithm. The effectiveness of our method is demonstrated through several numerical experiments.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 409-427"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-07-01Epub Date: 2026-01-12DOI: 10.1016/j.matcom.2026.01.009
Saleh Mobayen , Alireza Izadbakhsh
In modern industrial automation, the deployment of multiple robotic manipulators for cooperative operations has become increasingly common, offering enhanced system flexibility and responsiveness. However, as the number of manipulators increases, the system dynamics become substantially more nonlinear and complex, giving rise to unmodeled dynamics and various sources of uncertainty. Moreover, external disturbances can further degrade control performance, while the lack of a comprehensive sensing infrastructure may result in incomplete state information. To address these challenges, this study proposes a robust, model-independent control framework based on function approximation techniques. The methodology leverages linear differential equations with unknown coefficients to capture the aggregated system uncertainties under the assumption that such uncertainties can be effectively described using this structure. The approximation capability of the proposed model is then justified via the Stone-Weierstrass theorem, establishing the role of linear differential equations as universal approximators. Notably, the control strategy does not require velocity measurements, thereby simplifying its practical implementation. Stability analysis based on Lyapunov’s direct method ensures that tracking errors remain uniformly ultimately bounded. The controller is validated within a dual-arm cooperative manipulation scenario involving a rigid object, and its performance is benchmarked against three contemporary approximation-based control methods. Simulation results confirm the efficacy and robustness of the proposed approach.
{"title":"Cooperative and robust object manipulation by multiple robots via linear estimated state feedback","authors":"Saleh Mobayen , Alireza Izadbakhsh","doi":"10.1016/j.matcom.2026.01.009","DOIUrl":"10.1016/j.matcom.2026.01.009","url":null,"abstract":"<div><div>In modern industrial automation, the deployment of multiple robotic manipulators for cooperative operations has become increasingly common, offering enhanced system flexibility and responsiveness. However, as the number of manipulators increases, the system dynamics become substantially more nonlinear and complex, giving rise to unmodeled dynamics and various sources of uncertainty. Moreover, external disturbances can further degrade control performance, while the lack of a comprehensive sensing infrastructure may result in incomplete state information. To address these challenges, this study proposes a robust, model-independent control framework based on function approximation techniques. The methodology leverages linear differential equations with unknown coefficients to capture the aggregated system uncertainties under the assumption that such uncertainties can be effectively described using this structure. The approximation capability of the proposed model is then justified via the Stone-Weierstrass theorem, establishing the role of linear differential equations as universal approximators. Notably, the control strategy does not require velocity measurements, thereby simplifying its practical implementation. Stability analysis based on Lyapunov’s direct method ensures that tracking errors remain uniformly ultimately bounded. The controller is validated within a dual-arm cooperative manipulation scenario involving a rigid object, and its performance is benchmarked against three contemporary approximation-based control methods. Simulation results confirm the efficacy and robustness of the proposed approach.</div></div>","PeriodicalId":49856,"journal":{"name":"Mathematics and Computers in Simulation","volume":"245 ","pages":"Pages 384-408"},"PeriodicalIF":4.4,"publicationDate":"2026-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146078787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}