Yan Wang, Yining Yang, Nian Wang, Hong Li, Yang Liu
{"title":"Two-grid mixed finite element method combined with the BDF2-θ for a two-dimensional nonlinear fractional pseudo-hyperbolic wave equation","authors":"Yan Wang, Yining Yang, Nian Wang, Hong Li, Yang Liu","doi":"10.1016/j.rinam.2024.100530","DOIUrl":"10.1016/j.rinam.2024.100530","url":null,"abstract":"<div><div>In this article, a fast two-grid mixed finite element (T-GMFE) algorithm based on a time second-order discrete scheme with parameter <span><math><mi>θ</mi></math></span> is considered to numerically solve a class of two-dimensional nonlinear fractional pseudo-hyperbolic wave models. The weighted and shifted Grünwald difference (WSGD) formula is used to approximate the fractional time derivative at time <span><math><msub><mrow><mi>t</mi></mrow><mrow><mi>n</mi><mo>−</mo><mi>θ</mi></mrow></msub></math></span>, and the spatial direction is approximated by a two-grid <span><math><msup><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span>-Galerkin MFE method. The error estimates in both <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span> and <span><math><msup><mrow><mi>H</mi></mrow><mrow><mn>1</mn></mrow></msup></math></span>-norm for the fully discrete T-GMFE system are proved. Further, a modified T-GMFE scheme is proposed and the optimal error results are provided. Finally, computing results show the presented T-GMFE method can save computing time and improve the computational efficiency.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100530"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A new error analysis for finite element methods for elliptic Neumann boundary control problems with pointwise control constraints","authors":"Susanne C. Brenner, Li-Yeng Sung","doi":"10.1016/j.rinam.2025.100544","DOIUrl":"10.1016/j.rinam.2025.100544","url":null,"abstract":"<div><div>We present a new error analysis for finite element methods for a linear-quadratic elliptic optimal control problem with Neumann boundary control and pointwise control constraints. It can be applied to standard finite element methods when the coefficients in the elliptic operator are smooth and also to multiscale finite element methods when the coefficients are rough.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100544"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fully decoupled SAV Fourier-spectral scheme for the Cahn–Hilliard–Hele–Shaw system","authors":"Linhui Zhang , Hongen Jia , Hongbin Wang","doi":"10.1016/j.rinam.2024.100534","DOIUrl":"10.1016/j.rinam.2024.100534","url":null,"abstract":"<div><div>In this paper, we construct first- and second-order fully discrete schemes for the Cahn–Hilliard–Hele–Shaw system based on the Fourier-spectral method for spatial discretization. For temporal discretization, we combine two efficient approaches, including the scalar auxiliary variable (SAV) method for linearizing nonlinear potentials and the zero-energy-contribution method (ZEC) for decoupling nonlinear couplings. These schemes are linear, fully decoupled, and unconditionally energy stable, requiring only the solution of a sequence of elliptic equations with constant coefficients at each time step. The rigorous proof of the error analysis for the first-order scheme is shown. In addition, several numerical examples are presented to demonstrate the stability, accuracy, and efficiency of the proposed scheme.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100534"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Structured backward errors for block three-by-three saddle point systems with Hermitian and sparsity block matrices","authors":"Bing Tan, Wei Ma","doi":"10.1016/j.rinam.2025.100546","DOIUrl":"10.1016/j.rinam.2025.100546","url":null,"abstract":"<div><div>In this paper, we explore the structured backward errors for a class of block three-by-three saddle point systems with Hermitian and sparsity block matrices. We derive an explicit formula for the structured backward errors under the assumption that the inherent matrix structure and sparsity pattern are maintained in the associated perturbation. Moreover, the optimal backward perturbation matrix for achieving structured backward error is constructed. Our analysis further explores the structured backward error when the sparsity structure is not preserved. Numerical experiments show that the computable formulas of structured backward errors are useful for testing the stability of practical algorithms.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100546"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143474560","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"PINN based on multi-scale strategy for solving Navier–Stokes equation","authors":"Shirong Li , Shaoyong Lai","doi":"10.1016/j.rinam.2024.100526","DOIUrl":"10.1016/j.rinam.2024.100526","url":null,"abstract":"<div><div>Neural networks combined with automatic differentiation technology provide a fundamental framework for the numerical solution of partial differential equations. This framework constitutes a loss function driven by both data and physical models, significantly enhancing generalization capabilities. Combining the framework and the idea of multi-scale methods in traditional numerical methods, such as domain decomposition and collocation self-adaption, we construct a method of the Physics-Informed Neural Networks (PINNs) based on multi-scale strategy to solve Navier–Stokes equations, and the results are more effective than XPINNs and SAPINNs. The computational efficiency of the proposed method is verified by solving two-dimensional and three-dimensional Navier–Stokes equations.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100526"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fully discrete P02−P1 mixed elements for optimal control with parabolic equations and low regularity","authors":"Yuelong Tang, Yuchun Hua, Yujun Zheng, Chao Wu","doi":"10.1016/j.rinam.2025.100551","DOIUrl":"10.1016/j.rinam.2025.100551","url":null,"abstract":"<div><div>This paper studies a novel fully discrete mixed method for optimal control problems (OCPs) with parabolic equations and low regularity. The backward difference scheme and <span><math><mrow><msubsup><mrow><mi>P</mi></mrow><mrow><mn>0</mn></mrow><mrow><mn>2</mn></mrow></msubsup><mo>−</mo><msub><mrow><mi>P</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> mixed finite elements (MFEs) are used for temporal and spatial discretization of state and adjoint state, respectively. Error estimates of all variables are derived through the introduction of specific auxiliary variables and the application of suitable regularity assumptions. The theoretical analysis is validated by two numerical examples.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100551"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143487236","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Woojin Cho , Kookjin Lee , Noseong Park , Donsub Rim , Gerrit Welper
{"title":"FastLRNR and Sparse Physics Informed Backpropagation","authors":"Woojin Cho , Kookjin Lee , Noseong Park , Donsub Rim , Gerrit Welper","doi":"10.1016/j.rinam.2025.100547","DOIUrl":"10.1016/j.rinam.2025.100547","url":null,"abstract":"<div><div>We introduce <u>S</u>parse <u>P</u>hysics <u>In</u>formed Back<u>prop</u>agation (SPInProp), a new class of methods for accelerating backpropagation for a specialized neural network architecture called Low Rank Neural Representation (LRNR). The approach exploits the low rank structure within LRNR and constructs a reduced neural network approximation that is much smaller in size. We call the smaller network FastLRNR. We show that backpropagation of FastLRNR can be substituted for that of LRNR, enabling a significant reduction in complexity. We apply SPInProp to a physics informed neural networks framework and demonstrate how the solution of parametrized partial differential equations is accelerated.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100547"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Existence of multiple weak solutions to a weighted quasilinear elliptic equation","authors":"Khaled Kefi","doi":"10.1016/j.rinam.2024.100536","DOIUrl":"10.1016/j.rinam.2024.100536","url":null,"abstract":"<div><div>In this study, we explore the existence of solutions to certain quasilinear degenerate elliptic equations that involve Hardy singular coefficients. Using variational techniques and critical point theorems, we establish new criteria for the existence of at least three weak solutions, under the assumption that the nonlinearity meets appropriate conditions.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100536"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143098469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The numerical solution of an Abel integral equation by the optimal quadrature formula","authors":"Abdullo Hayotov , Samandar Babaev , Bobomurod Boytillayev","doi":"10.1016/j.rinam.2025.100542","DOIUrl":"10.1016/j.rinam.2025.100542","url":null,"abstract":"<div><div>In this study, a novel and efficient approach utilizing optimal quadrature formulas is introduced to derive approximate solutions for generalizing Abel’s integral equations. The method, characterized by high accuracy and simplicity, involves constructing optimal quadrature formulas in the sense of Sard and providing error estimates within the Hilbert space of differentiable functions. The squared norm of the error functional for the quadrature formula in the space <span><math><mrow><msubsup><mrow><mi>W</mi></mrow><mrow><mn>2</mn></mrow><mrow><mrow><mo>(</mo><mn>2</mn><mo>.</mo><mn>1</mn><mo>)</mo></mrow></mrow></msubsup><mrow><mo>(</mo><mn>0</mn><mo>,</mo><mi>t</mi><mo>)</mo></mrow></mrow></math></span> is computed. To minimize this error, a system of linear equations regarding the formula’s coefficients is derived, leading to a unique solution. Then the explicit expressions for these optimal coefficients are obtained. The validity of the approach is demonstrated by solving several integral equations, with approximation errors presented in the corresponding tables.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100542"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143149999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Two step inertial Tseng method for solving monotone variational inclusion problem","authors":"Lehlogonolo Mokaba , Hammed Anuoluwapo Abass , Abubakar Adamu","doi":"10.1016/j.rinam.2025.100545","DOIUrl":"10.1016/j.rinam.2025.100545","url":null,"abstract":"<div><div>In this paper, we examine the monotone variational inclusion problem with a maximal monotone operator and a Lipschitz continuous monotone operator. We propose two different iterative algorithms for solving the monotone variational inclusion problem, utilizing a new self-adaptive step size and a two-step inertial technique. Under the assumption that the solution set of the monotone variational inclusion problem is nonempty, we prove weak and strong convergence theorems concerning the sequences generated by our proposed algorithms. The convergence is guaranteed under some mild assumptions. Some numerical experiments are presented to demonstrate the performance of our iterative algorithms in comparison with recent results in the literature.</div></div>","PeriodicalId":36918,"journal":{"name":"Results in Applied Mathematics","volume":"25 ","pages":"Article 100545"},"PeriodicalIF":1.4,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143150012","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}