检索结果-南通市图书馆

Fixed Subgroups are not Compressed in Direct Products of Surface Groups

在线全文

学校读者我要写书评

暂无评论

Chinese Annals of mathematics,Series B 2024年第5期45卷 703-708页

作者： Qiang ZHANG Jianchun WU Fanling GU School of mathematics and {1. Xi'an Jiaotong University department of {1. Soochow University School of mathematics and {1. Xi'an Jiaotong University School of General Education Guangzhou College of Technology and Business

By constructing counterexamples, the authors show that the fixed subgroups are not compressed in direct products of free and surface groups, and hence negate a conjecture in [Zhang, Q., Ventura, E. and J. Wu, Fixed su... 详细信息

关键词： 20F34 20F65 57M07 Compression Direct product Fixed subgroup Free group Inertia Surface group

The KAM theorem on the modulus of continuity about parameters

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China mathematics 2024年第3期67卷 577-592页

作者： Zhicheng Tong Jiayin Du Yong Li School of mathematics Jilin UniversityChangchun 130012China Institute of mathematics Jilin UniversityChangchun 130012China School of mathematics and {1. Center for Mathematics and Interdisciplinary SciencesNortheast Normal UniversityChangchun 130024China

In this paper,we study the Hamiltonian systems H(y,x,ξ,ε)=〈ω(ξ),y〉+εP(y,x,ξ,ε),where ω and P are continuous about ξ.We prove that persistent invariant tori possess the same frequency as the unperturbed tori,under a certain transversality condition and a weak convexity condition for the frequency mapping ω.As a direct application,we prove a Kolmogorov-Arnold-Moser(KAM) theorem when the perturbation P holds arbitrary Holder continuity with respect to the parameter ξ.The infinite-dimensional case is also *** our knowledge,this is the first approach to the systems with the only continuity in the parameter beyond H?lder's type.

关键词： Hamiltonian systems invariant tori frequency-preserving weak regularity

BIG HANKEL OPERATORS ON HARDY SPACES OF STRONGLY PSEUDOCONVEX DOMAINS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第3期44卷 789-809页

作者：陈伯勇江良英 School of Mathematical Sciences Fudan UniversityShanghai200433China department of {1. and mathematics Shanghai Lixin University of Accounting and FinanceShanghai201209China

In this article,we investigate the(big) Hankel operator H_(f) on the Hardy spaces of bounded strongly pseudoconvex domains Ω in C^(n).We observe that H_(f ) is bounded on H~p(Ω)(1.

详细信息

In this article,we investigate the(big) Hankel operator H_(f) on the Hardy spaces of bounded strongly pseudoconvex domains Ω in C^(n).We observe that H_(f ) is bounded on H~p(Ω)(1.1.≤p≤∞) of bounded strongly pseudoconvex domains.

关键词： Hankel operator Hardy space Bergman space pseudoconvex domain

A Local Macroscopic Conservative(LoMaC)Low Rank Tensor Method with the Discontinuous Galerkin Method for the Vlasov Dynamics

在线全文

学校读者我要写书评

暂无评论

Communications on Applied mathematics and Computation 2024年第1期6卷 550-575页

作者： Wei Guo Jannatul Ferdous Ema Jing-Mei Qiu department of {1. and statistics Texas Tech UniversityLubbockTX70409USA department of Mathematical Sciences University of DelawareNewarkDE19716USA

In this paper,we propose a novel Local Macroscopic Conservative(LoMaC)low rank tensor method with discontinuous Galerkin(DG)discretization for the physical and phase spaces for simulating the Vlasov-Poisson(VP)*** LoMaC property refers to the exact local conservation of macroscopic mass,momentum,and energy at the discrete *** recently developed LoMaC low rank tensor algorithm(arXiv:2207.0051.)simultaneously evolves the macroscopic conservation laws of mass,momentum,and energy using the kinetic flux vector splitting;then the LoMaC property is realized by projecting the low rank kinetic solution onto a subspace that shares the same macroscopic *** paper is a generalization of our previous work,but with DG discretization to take advantage of its compactness and flexibility in handling boundary conditions and its superior accuracy in the long *** algorithm is developed in a similar fashion as that for a finite difference scheme,by observing that the DG method can be viewed equivalently in a nodal *** the nodal DG method,assuming a tensorized computational grid,one will be able to(i)derive differentiation matrices for different nodal points based on a DG upwind discretization of transport terms,and(ii)define a weighted inner product space based on the nodal DG grid *** algorithm can be extended to the high dimensional problems by hierarchical Tucker(HT)decomposition of solution tensors and a corresponding conservative projection *** a similar spirit,the algorithm can be extended to DG methods on nodal points of an unstructured mesh,or to other types of discretization,e.g.,the spectral method in velocity *** numerical results are performed to showcase the efficacy of the method.

关键词： Hierarchical Tucker(HT)decomposition Conservative SVD Energy conservation Discontinuous Galerkin(DG)method

The Complete Classification of Graphs whose Second Largest Eigenvalue of the Eccentricity Matrix is Less Than 1

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

Acta Mathematica Sinica,English Series 2024年第7期40卷 1741-1766页

作者： Jian Feng WANG Xing Yu LEI Shu Chao LI Zoran STANIC School of mathematics and {1. Shandong University of TechnologyZibo255049P.R.China Faculty of mathematics and {1. Central China Normal UniversityWuhan430079P.R.China Faculty of mathematics University of BelgradeStudentski trg 1611000BelgradeSerbia

The eccentricity matrix of a graph is obtained from the distance matrix by keeping the entries that are largest in their row or column,and replacing the remaining entries by *** matrix can be interpreted as an opposite to the adjacency matrix,which is on the contrary obtained from the distance matrix by keeping only the entries equal to *** the paper,we determine graphs having the second largest eigenvalue of eccentricity matrix less than 1.

关键词： Eccentricity matrix eigenvalue diameter principal submatrix forbidden subgraph

Casson hybrid nanofluid flow over a Riga plate for drug deliveryapplications with double diffusion

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2024年第10期33卷 311-320页

作者： Abeer S.Alnahdi Taza Gul department of {1. and statistics Faculty of ScienceImam Mohammad Ibn Saud Islamic University(IMSIU)RiyadhSaudi Arabia department of {1. City University of Science and Information Technology25000PeshawarPakistan DGoST-Directorate General of Science&Technology Khyber PakhtunkhwaPeshawarPakistan

Casson fluid-mediated hybrid nanofluids are more effective at transferring heat than traditional heat transfer fluids in terms of thermal *** exchangers,cooling systems and other thermal management systems are ideal for use with Casson *** control of the flow and release of medication is necessary when using Casson fluids in drug delivery systems because of their unique rheological *** involves the creation of nanoparticles that are loaded with drugs and distributed in Casson fluid-based carriers for targeted *** this study,to create a hybrid nanofluid,both single-walled carbon nanotubes(SWCNTs)and multi-walled carbon nanotubes(MWCNTs)are dispersed in a Casson fluid with Fourier’s and Fick’s laws *** Casson fluid is suitable for various engineering and medical applications due to the enhancement of heat transfer and thermal conductivity by the carbon *** objective is to understand how SWCNTs and MWCNTs impact the flow field by studying the flow behavior of the Casson hybrid nanofluid when it is stretched against a Riga *** Darcy-Forchheimer model is also used to account for the impact of the porous medium near the stretching *** linear and quadratic drag terms are taken into account in this model to accurately predict the flow behavior of the *** addition,the homotopy analysis method is utilized to address the model *** outcomes are discussed and deliberated based on drug delivery *** findings shed valuable light on the flow characteristics of a Casson hybrid nanofluid comprising SWCNTs and *** is observed that the incorporation of carbon nanotubes makes the nanofluid a promising candidate for medical applications due to its improved heat transfer properties.

关键词： carbon nanotubes(CNTs) Riga plate Casson fluid with Fourier’s and Fick’s laws analytical solutions

APPROXIMATELY ARTINIAN （NOETHERIAN） C*-ALGEBRAS

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Scientia 2024年第6期44卷 2485-2497页

作者： Mohammad ROUZBEHANI Massoud AMINI Mohammad B.ASADI School of mathematics Statistics and Computer ScienceCollege of ScienceUniversity of Tehran department of {1. Faculty of Mathematical SciencesTarbiat Modares University School of mathematics Institute for Research in Fundamental Sciences (IPM)

In this article,we introduce and study the class of approximately Artinian（Noetherian） C*-algebras,called AR-algebras（AN-algebras）,which is a simultaneous generalization of Artinian（Noetherian） C*-algebras and *** study properties such as the ideal property and topological dimension zero for *** particular,we show that a faithful AR or AN algebra is strongly purely infinite iff it is purely infinite iff it is weakly purely *** extends the Kirchberg's O∞-absorption theorem,and implies that a weakly purely infinite C*-algebra is Noetherian iff every its ideal has a full projection.

关键词： (weakly) purely infinite 46L05 46L80 Artinian C*-algebra graph C*-algebra ideal property inductive limit Noetherian

Nonlinear Extrapolation Estimates of π

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematicae Applicatae Sinica 2024年第1期40卷 91-108页

作者： Wen-qing Xu Sha-sha Wang Da-chuan Xu Beijing Institute for Scientific and Engineering Computing Beijing University of TechnologyBeijing100124China department of {1. and statistics California State UniversityLong BeachCalifornia90840USA department of {1. and Physics Shijiazhuang Tiedao UniversityShijiazhuang050043China

The classical Archimedean approximation of π uses the semiperimeter or area of regular polygons inscribed in or circumscribed about a unit circle in R~2 and it is well-known that by using linear combinations of these basic estimates,modern extrapolation techniques can greatly speed up the approximation ***,when n vertices are randomly selected on the circle,the semiperimeter and area of the corresponding random inscribed and circumscribing polygons are known to converge to π almost surely as n→∞,and by further applying extrapolation processes,faster convergence rates can also be achieved through similar linear combinations of the semiperimeter and area of these random *** this paper,we further develop nonlinear extrapolation methods for approximating π through certain nonlinear functions of the semiperimeter and area of such *** focus on two types of extrapolation estimates of the forms χ_n=S_n~αA_n~β and Y_n(p)=(αS_n~p+βA_n~p)~(1.p) where α+β=1.p≠0,and Sn and An respectively represents the semiperimeter and area of a random n-gon inscribed in the unit circle in R~2,and Xn may be viewed as the limit of Y_n(p) when p→*** deriving probabilistic asymptotic expansions with carefully controlled error estimates for Xn and Y_n(p),we show that the choice α=4/3,β=-1.3 minimizes the approximation error in both cases,and their distributions are also asymptotically normal.

关键词： Archimedean polygons random polygons approximations ofπ extrapolation processes asymptotic convergence

Bound-Preserving Discontinuous Galerkin Methods with Modified Patankar Time Integrations for Chemical Reacting Flows

在线全文

学校读者我要写书评

暂无评论

Communications on Applied mathematics and Computation 2024年第1期6卷 190-217页

作者： Fangyao Zhu Juntao Huang Yang Yang department of Mathematical Sciences Michigan Technological UniversityHoughtonMI49931USA department of {1. and statistics Texas Tech UniversityLubbockTX79409USA

In this paper,we develop bound-preserving discontinuous Galerkin(DG)methods for chemical reactive *** are several difficulties in constructing suitable numerical *** of all,the density and internal energy are positive,and the mass fraction of each species is between 0 and ***,due to the rapid reaction rate,the system may contain stiff sources,and the strong-stability-preserving explicit Runge-Kutta method may result in limited time-step *** obtain physically relevant numerical approximations,we apply the bound-preserving technique to the DG *** traditional positivity-preserving techniques can successfully yield positive density,internal energy,and mass fractions,they may not enforce the upper bound 1.of the mass *** solve this problem,we need to(i)make sure the numerical fluxes in the equations of the mass fractions are consistent with that in the equation of the density;(ii)choose conservative time integrations,such that the summation of the mass fractions is *** the above two conditions,the positive mass fractions have summation 1.and then,they are all between 0 and *** time discretization,we apply the modified Runge-Kutta/multi-step Patankar methods,which are explicit for the flux while implicit for the *** methods can handle stiff sources with relatively large time steps,preserve the positivity of the target variables,and keep the summation of the mass fractions to be ***,it is not straightforward to combine the bound-preserving DG methods and the Patankar time *** positivity-preserving technique for DG methods requires positive numerical approximations at the cell interfaces,while Patankar methods can keep the positivity of the pre-selected point values of the target *** match the degree of freedom,we use polynomials on rectangular meshes for problems in two space *** evolve in time,we first read the polynomials at the Gaussian ***,suitable slope l

关键词： Compressible Euler equations Chemical reacting flows Bound-preserving Discontinuous Galerkin(DG)method Modified Patankar method