Journal of Computational and Applied Mathematics最新文献_第3页

Mixtures of common factor analyzers using the restricted multivariate skew-t distribution for clustering high-dimensional data with missing values 使用限制多变量偏t分布的共因子分析混合聚类具有缺失值的高维数据

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-11 DOI: 10.1016/j.cam.2025.116708

Wan-Lun Wang , Luis M. Castro , Shi-Xiu Yu , Tsung-I Lin

{"title":"Mixtures of common factor analyzers using the restricted multivariate skew-t distribution for clustering high-dimensional data with missing values","authors":"Wan-Lun Wang , Luis M. Castro , Shi-Xiu Yu , Tsung-I Lin","doi":"10.1016/j.cam.2025.116708","DOIUrl":"10.1016/j.cam.2025.116708","url":null,"abstract":"<div><div>Mixtures of common restricted skew-<span><math><mi>t</mi></math></span> factor analyzers (MCrstFA) have emerged as a parsimonious and practical approach for the model-based clustering of high-dimensional data with asymmetric features and outlying observations in one or more heterogeneous populations. However, missing data has become a ubiquitous problem that frequently adds complexity to the analyses for practitioners. Most existing tools are not adaptable to data with missing values, which is a significant reason for this complexity. This paper proposes an extension of the MCrstFA framework that allows the analyst to parsimoniously model data with missing values, skewness, heavy tails, and multimodality simultaneously. Under the missing at random (MAR) mechanism for nonresponses, a computationally feasible expectation conditional maximization either (ECME) algorithm is developed for computing maximum likelihood (ML) estimates of model parameters. The estimation procedure enables the automatic imputation of missing values and the prediction of unobserved factor scores. To assess the precision of the ML estimators, an information matrix-based approach is employed to approximate the asymptotic covariance matrix of the estimators. Numerical results obtained from the analysis of simulated and real datasets illustrate the effectiveness of the proposed methodology.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"471 ","pages":"Article 116708"},"PeriodicalIF":2.1,"publicationDate":"2025-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144084447","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}

引用次数: 0

Stable iterative refinement for solving linear systems with inaccurate computation 求解计算不准确的线性系统的稳定迭代细化

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-09 DOI: 10.1016/j.cam.2025.116746

Chai Wah Wu, Mark S. Squillante, Vassilis Kalantzis, Lior Horesh

引用次数: 0

Existence results for generalized 2D fractional partial integro-differential equations 广义二维分数阶偏积分-微分方程的存在性结果

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-09 DOI: 10.1016/j.cam.2025.116705

Maryam Moghaddamfar , Manochehr Kazemi , Reza Ezzati

引用次数: 0

Derivative-free projection CG-based algorithm with restart strategy for solving convex-constrained nonlinear monotone equations and its application to logistic regression 求解凸约束非线性单调方程的无导数投影算法及其在逻辑回归中的应用

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-08 DOI: 10.1016/j.cam.2025.116676

Auwal Bala Abubakar , Abdulkarim Hassan Ibrahim , Yuming Feng

引用次数: 0

Optimality conditions for a class of nonsmooth semidefinite bilevel optimization problems via convexifications applied to bilevel supply chain under uncertainty 一类基于凸化的非光滑半定双层优化问题的最优性条件，应用于不确定双层供应链

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-06 DOI: 10.1016/j.cam.2025.116734

Youness El-Yahyaoui , Mohsine Jennane , El Mostafa Kalmoun , Lahoussine Lafhim

引用次数: 0

HTL-WASI preconditioner for finite element discretization of complex ADR equation and its application 复杂ADR方程有限元离散化的html - wasi预条件及其应用

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-04 DOI: 10.1016/j.cam.2025.116726

Ronghua Yang , Junxian Wang , Shi Shu

{"title":"HTL-WASI preconditioner for finite element discretization of complex ADR equation and its application","authors":"Ronghua Yang , Junxian Wang , Shi Shu","doi":"10.1016/j.cam.2025.116726","DOIUrl":"10.1016/j.cam.2025.116726","url":null,"abstract":"<div><div>The convection diffusion reaction (ADR) equation is widely used in engineering applications. In this paper, we focus on a complex ADR equation arising from Helmholtz equation with impedance boundary conditions, prove the coerceiveness and boundedness of the sesquilinear functional and discuss the fast solver of the discretization. Firstly, we design a Weighted Additive Schwarz with Impedance (WASI) preconditioner, in order to overcome the dependence of the WASI preconditioner on the number of subdomains and the overlapping width, an ideal coarse space is designed. Although it can be proved that the corresponding hybrid two-level preconditioner is the exact inverse of the ADR coefficient matrix, the dimension of this coarse space is too big. In order to overcome this deficiency, a smaller dimensional coarse space was constructed by introducing local generalized eigenvalue problems (GEP) on each subdomain, and the descent rate of the corresponding two-level preconditioned GMRES method was rigorously analyzed which does not depend on mesh size, overlapping width, wave number <span><math><mi>k</mi></math></span>, and the absorption parameter. Since the size of the coarse space is sensitive to <span><math><mi>k</mi></math></span> and the GEP on each subdomain needs to be solved, the computational cost is too high. Therefore, we design an iterative method based on an economical two-level preconditioner, and establish a heuristic convergence theory that is supported by numerical results. Numerical experiments show the robustness of GMRES with the corresponding economical two-level preconditioner(HTLE-WASI-GMRES). Finally, for the Helmholtz finite element discretization, by using the Shifted Laplace technique and ADR equation, we design a novel fast solver combining with HTLE-WASI-GMRES for ADR equation. Numerical experiments have demonstrated the effectiveness of the algorithm.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116726"},"PeriodicalIF":2.1,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906767","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}

引用次数: 0

An algorithm for the estimation of the segmental Lebesgue constant 一种估计分段勒贝格常数的算法

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-04 DOI: 10.1016/j.cam.2025.116745

Ludovico Bruni Bruno , Giacomo Elefante

引用次数: 0

Multiscale method for image denoising using nonlinear diffusion process: Local denoising and spectral multiscale basis functions 非线性扩散过程图像去噪的多尺度方法：局部去噪和谱多尺度基函数

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-04 DOI: 10.1016/j.cam.2025.116733

Maria Vasilyeva , Aleksei Krasnikov , Kelum Gajamannage , Mehrube Mehrubeoglu

{"title":"Multiscale method for image denoising using nonlinear diffusion process: Local denoising and spectral multiscale basis functions","authors":"Maria Vasilyeva , Aleksei Krasnikov , Kelum Gajamannage , Mehrube Mehrubeoglu","doi":"10.1016/j.cam.2025.116733","DOIUrl":"10.1016/j.cam.2025.116733","url":null,"abstract":"<div><div>We consider image denoising using a nonlinear diffusion process, where we solve unsteady partial differential equations with nonlinear coefficients. The noised image is given as an initial condition, and nonlinear coefficients are used to preserve the main image features. In this paper, we present a multiscale method for the resulting nonlinear parabolic equation in order to construct an efficient solver. To both filter out noise and preserve essential image features during the denoising process, we utilize a time-dependent nonlinear diffusion model. Here, the noised image is fed as an initial condition and the denoised image is stimulated with given parameters. We numerically implement this model by constructing a discrete system for a given image resolution using a finite volume method and employing an implicit time approximation scheme to avoid time-step restriction. However, the resulting discrete system size is proportional to the number of pixels which leads to computationally expensive numerical algorithms for high-resolution images. In order to reduce the size of the system and construct efficient computational algorithms, we construct a coarse-resolution representation of the system. We incorporate local noise reduction in the coarsening process to construct an efficient algorithm with fewer denoising iterations. We propose a computational approach with two main ingredients: (1) performing local image denoising in each local domain of basis support; and (2) constructing multiscale basis functions to construct a coarse resolution representation by a Galerkin coupling. We present numerical results for several classic and high-resolution image datasets to demonstrate the effectiveness of the proposed multiscale approach with local denoising and local multiscale representation.</div></div>","PeriodicalId":50226,"journal":{"name":"Journal of Computational and Applied Mathematics","volume":"470 ","pages":"Article 116733"},"PeriodicalIF":2.1,"publicationDate":"2025-05-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143906768","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}

引用次数: 0

Well-balanced POD-based reduced-order models for finite volume approximation of hyperbolic balance laws 双曲平衡律有限体积逼近的基于良好平衡pod的降阶模型

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-04 DOI: 10.1016/j.cam.2025.116735

I. Gómez-Bueno , E.D. Fernández-Nieto , S. Rubino

引用次数: 0

Bayesian credible regions for two-parameter exponential distributions under type-II censoring ii型滤波下双参数指数分布的贝叶斯可信区域

IF 2.1 2区数学

Journal of Computational and Applied Mathematics Pub Date : 2025-05-03 DOI: 10.1016/j.cam.2025.116721

A. Saadati Nik , A. Asgharzadeh , A.J. Fernández

引用次数: 0