检索结果-南通市图书馆

Iterative Subregion Correction Preconditioners with Adaptive Tolerance for Problems with Geometrically Localized Stiffness

引用

Communications on Applied Mathematics and Computation 2024年第2期6卷 811-836页

作者： Michael Franco Per-Olof Persson Will Pazner department of Mathematics University of CaliforniaBerkeleyBerkeleyCA 94720-3840USA Fariborz Maseeh department of Mathematics and statistics Portland State UniversityPortlandOR 97201USA

We present a class of preconditioners for the linear systems resulting from a finite element or discontinuous Galerkin discretizations of advection-dominated *** preconditioners are designed to treat the case of geometrically localized stiffness,where the convergence rates of iterative methods are degraded in a localized subregion of the *** convergence may be caused by a number of factors,including the mesh size,anisotropy,highly variable coefficients,and more challenging *** approach taken in this work is to correct well-known preconditioners such as the block Jacobi and the block incomplete LU(ILU)with an adaptive inner subregion *** goal of these preconditioners is to reduce the number of costly global iterations by accelerating the convergence in the stiff region by iterating on the less expensive reduced *** tolerance for the inner iteration is adaptively chosen to minimize subregion-local work while guaranteeing global convergence *** present analysis showing that the convergence of these preconditioners,even when combined with an adaptively selected tolerance,is independent of discretization parameters(e.g.,the mesh size and diffusion coefficient)in the *** demonstrate significant performance improvements over black-box preconditioners when applied to several model convection-diffusion ***,we present performance results of several variations of iterative subregion correction preconditioners applied to the Reynolds number 2.25×10^(6)fluid flow over the NACA 0012 airfoil,as well as massively separated flow at 30°angle of attack.

关键词： Subregion correction Nested Krylov Geometrically localized stiffness

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asymptotic Inference in the Random Coefficient Autoregressive Model with Time-functional Variance Noises

引用

Acta Mathematicae Applicatae Sinica 2024年第2期40卷 320-346页

作者： En-wen ZHU Zi-wei DENG Han-jun ZHANG Jun CAO Xiao-hui LIU department of Mathematics and statistics Changsha University of Science and TechnologyChangsha 410114China School of Mathematics and Computational Science Xiangtan UniversityXiangtan 411105China School of statistics and Data Science and Key Laboratory of Data Science in Finance and EconomicsJiangxi University of Finance and EconomicsNanchang 330013China

This paper considers the random coefficient autoregressive model with time-functional variance noises,hereafter the RCA-TFV *** first establish the consistency and asymptotic normality of the conditional least squares estimator for the constant *** semiparametric least squares estimator for the variance of the random coefficient and the nonparametric estimator for the variance function are constructed,and their asymptotic results are reported.A simulation study is presented along with an analysis of real data to assess the performance of our method in finite samples.

关键词： random coefficient autoregressive model time-functional variance conditional least squares semiparametric least squares

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

On the Infinite-Dimensional Modular Lie Superalgebras of O-Type

引用

Algebra Colloquium 2024年第2期31卷 347-360页

作者： Xiaoning Xu Jing Zhao Yucai Su School of Mathematics and statistics Liaoning UniversityShenyang 110036China 不详

The natural filtrations of infinite-dimensional Lie superalgebras of O-type over a field of positive characteristic are proved to be invariant under automorphisms by studying ad-nilpotent *** observe that two Lie superalgebras of O-type are isomorphic if and only if the integers in the definition of these Lie superalgebras are ***,all the Lie superalgebras of O-type are classified in the sense of isomorphism.

关键词： filtration isomorphism classification

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

DYNAMICS FOR A CHEMOTAXIS MODEL WITH GENERAL LOGISTIC DAMPING AND SIGNAL DEPENDENT MOTILITY

引用

Acta Mathematica Scientia 2024年第3期44卷 1046-1063页

作者：涂馨予穆春来邱蜀燕张静 School of Mathematics and statistics Southwest UniversityChongqing400715China department of Applied Mathematics The Hong Kong Polytechnic UniversityHung HomHong KongChina College of Mathematics and statistics Chongqing UniversityChongqing401331China School of Sciences Southwest Petroleum UniversityChengdu610500China

In this paper,we consider the fully parabolic Chemotaxis system with the general logistic source{ut=Δ(γ(v)u)+λu-μu^(k),x∈Ω,t>0,vt=△v+wz,x∈Ω,t>0,wt=-wz,x∈Ω,t>0,zt=△z-z+u,x∈Ω,t>0 whereΩ⊂ℝn(n≥1)is a smooth and bounded domain,λ≥0,μ≥0,κ>1,and the motility function satisfies thatγ(v)∈C3([0,∞)),γ(v)>0,γ′(v)≤0 for all v≥*** the Neumann boundary condition,we obtain the global boundedness of solutions if one of the following conditions holds:(i)λ=μ=0,1≤nλ3;(ii)λ>0,μ>0,combined withκ>1,1≤n≤3 or k>n+2/4,,n>***,we prove that the solution (u, v, w, z) exponentially converges to the constant steady state ((λ/μ)1/k-1,∫Ωv0dx+∫Ωw0dx/|Ω|,0,(λ/μ)1/k-1).

关键词： chemotaxis signal-dependent motility logistic source boundedness asymptotic behavior

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

THE OPTIMAL LARGE TIME BEHAVIOR OF3D QUASILINEAR HYPERBOLIC EQUATIONS WITH NONLINEAR DAMPING

引用

Acta Mathematica Scientia 2024年第3期44卷 1064-1095页

作者：王涵张映辉 School of Mathematics and statistics Guangxi Normal UniversityGuilin541004China

We are concerned with the large-time behavior of 3D quasilinear hyperbolic equations with nonlinear *** main novelty of this paper is ***,we prove the optimal decay rates of the second and third order spatial derivatives of the solution,which are the same as those of the heat equation,and in particular,are faster than ones of previous related ***,for well-chosen initial data,we also show that the lower optimal L^(2) convergence rate of the k(∈[0,3])-order spatial derivatives of the solution is(1+t)^(-(2+2k)/4).Therefore,our decay rates are optimal in this *** proofs are based on the Fourier splitting method,low-frequency and high-frequency decomposition,and delicate energy estimates.

关键词： quasilinear hyperbolic equations large time behavior optimal decay rates

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

引用

Science China Mathematics 2024年第2期67卷 405-430页

作者： Junzhuo Gao Lei Wang Heng Lian School of statistics and Data Science&LPMC Nankai UniversityTianjin 300071China department of Mathematics City University of Hong KongHong KongChina

In this paper, we consider the unified optimal subsampling estimation and inference on the lowdimensional parameter of main interest in the presence of the nuisance parameter for low/high-dimensionalgeneralized linear models (GLMs) with massive data. We first present a general subsampling decorrelated scorefunction to reduce the influence of the less accurate nuisance parameter estimation with the slow convergencerate. The consistency and asymptotic normality of the resultant subsample estimator from a general decorrelatedscore subsampling algorithm are established, and two optimal subsampling probabilities are derived under theA- and L-optimality criteria to downsize the data volume and reduce the computational burden. The proposedoptimal subsampling probabilities provably improve the asymptotic efficiency of the subsampling schemes in thelow-dimensional GLMs and perform better than the uniform subsampling scheme in the high-dimensional GLMs.A two-step algorithm is further proposed to implement, and the asymptotic properties of the correspondingestimators are also given. Simulations show satisfactory performance of the proposed estimators, and twoapplications to census income and Fashion-MNIST datasets also demonstrate its practical applicability.

关键词： A-optimality decorrelated score subsampling high-dimensional inference L-optimality massive data

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Global Solutions to Nonconvex Problems by Evolution of Hamilton-Jacobi PDEs

引用

Communications on Applied Mathematics and Computation 2024年第2期6卷 790-810页

作者： Howard Heaton Samy Wu Fung Stanley Osher Typal Research Typal LLCLos AngelesUSA department of Applied Mathematics and statistics Colorado School of MinesGoldenUSA department Mathematics UCLALos AngelesUSA

Computing tasks may often be posed as optimization *** objective functions for real-world scenarios are often nonconvex and/or ***-of-the-art methods for solving these problems typically only guarantee convergence to local *** work presents Hamilton-Jacobi-based Moreau adaptive descent(HJ-MAD),a zero-order algorithm with guaranteed convergence to global minima,assuming continuity of the objective *** core idea is to compute gradients of the Moreau envelope of the objective(which is"piece-wise convex")with adaptive smoothing *** of the Moreau envelope(i.e.,proximal operators)are approximated via the Hopf-Lax formula for the viscous Hamilton-Jacobi *** numerical examples illustrate global convergence.

关键词： Global optimization Moreau envelope Hamilton-Jacobi Hopf-Lax-Cole-Hopf Proximals Zero-order optimization

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

The Path-Connectivity of Hierarchical Cubic Networks

引用

Acta Mathematicae Applicatae Sinica 2024年

作者： Ruo-xuan LI Rong-xia HAO Zhen HE Young Soo KWON School of Mathematics and statistics Beijing Jiaotong University department of Mathematics Yeungnam University

Let G be a simple connected graph with vertex set V （G）.For S?V （G）,letπG（S） denote the maximum cardinality of internally disjoint S-paths in *** an integer k with k≥2,the k-path-connectivityπk（G） is defined as the minimumπG（S） over all k-subsets S of V （G）.It is proved that deciding whetherπG（S）≥r is NP-complete problem[Graphs Combin.37 （2021） 2521–2533].The hypercube Qn is the famous Cayley graph,which is widely studied in the research of developing multiprocessor *** hierarchical cubic network HCNn is given in[IEEE TPDS 6 （1995） 427–435]which takes Qn as building clusters and emulates the desirable properties very *** this paper,we consider the 3-path-connectivity of HCN_n and prove that π3（HCN_n） = [（3n+2）/4] for n≥2 by constructing multiple internally disjoint *** result improves the 3-tree-connectivity[Discrete ***.322 （2022） 203–209]from trees to paths.

关键词：

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

A Note on P m-Factorizable Topological Groups

引用

Journal of Mathematical Research with Applications 2024年第2期44卷 209-212页

作者： Chunjie MA Liangxue PENG Beijing University of Technology School of Mathematics department of Mathematics statistics and Mechanics

In this paper, we define a new class of P m-factorizable topological groups. A topological group G is called P m-factorizable if, for every continuous function f : G → M to a metrizable space M, one can find a perfect homomorphism π : G → K onto a second-countable topological group K and a continuous function g : K → M such that f = g■π. We show that a topological group G is P m-factorizable if and only if it is P R-factorizable. And we get that if G is a P m-factorizable topological group and K is any compact topological group, then the group G × K is P m-factorizable.

关键词： R-factorizable PR-factorizable m-factorizable Pm-factorizable M-factorizable

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Endomorphism Algebras of Support τ-Tilting Modules

引用

Algebra Colloquium 2024年第2期31卷 333-340页

作者： Yonggang Hu Panyue Zhou Nanqing Ding department of International Economics China Foreign Affairs University Beijing 100037China School of Mathematics and statistics Changsha University of Science and Technology Changsha 410114China 不详

Let A be a finite dimensional k-algebra and T be a supportτ-tilting right *** this note,we give lower and upper bounds for the global dimension of the endomorphism algebra End_(A)(T)under some mild ***,we give some e... 详细信息

关键词： supportτ-tilting module τ-tilting module tilting module global dimension

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：