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Sharp upper bounds for the adjacency and the signless Laplacian spectral radius of graphs 被引量:1
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作者 WU Xian-zhang LIU Jian-ping 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2019年第1期100-112,共13页
Let G be a simple graph with n vertices and m edges. In this paper, we present some new upper bounds for the adjacency and the signless Laplacian spectral radius of graphs in which every pair of adjacent vertices has ... Let G be a simple graph with n vertices and m edges. In this paper, we present some new upper bounds for the adjacency and the signless Laplacian spectral radius of graphs in which every pair of adjacent vertices has at least one common adjacent vertex. Our results improve some known upper bounds. The main tool we use here is the Lagrange identity. 展开更多
关键词 graph SPECTRAL RADIUS signless LAPLACIAN SPECTRAL RADIUS upper BOUND
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THE MAXIMUM AND MINIMUM DEGREES OF RANDOM BIPARTITE MULTIGRAPHS 被引量:1
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作者 陈爱莲 张福基 李皓 《Acta Mathematica Scientia》 SCIE CSCD 2011年第3期1155-1166,共12页
In this paper the authors generalize the classic random bipartite graph model, and define a model of the random bipartite multigraphs as follows:let m = m(n) be a positive integer-valued function on n and ζ(n,m;{... In this paper the authors generalize the classic random bipartite graph model, and define a model of the random bipartite multigraphs as follows:let m = m(n) be a positive integer-valued function on n and ζ(n,m;{pk}) the probability space consisting of all the labeled bipartite multigraphs with two vertex sets A ={a_1,a_2,...,a_n} and B = {b_1,b_2,...,b_m}, in which the numbers t_(ai),b_j of the edges between any two vertices a_i∈A and b_j∈ B are identically distributed independent random variables with distribution P{t_(ai),b_j=k}=pk,k=0,1,2,...,where pk ≥0 and ∞Σk=0 pk=1. They obtain that X_(c,d,A), the number of vertices in A with degree between c and d of G_(n,m)∈ζ(n, m;{pk}) has asymptotically Poisson distribution, and answer the following two questions about the space ζ(n,m;{pk}) with {pk} having geometric distribution, binomial distribution and Poisson distribution, respectively. Under which condition for {pk} can there be a function D(n) such that almost every random multigraph G_(n,m)∈ζ(n,m;{pk}) has maximum degree D(n)in A? under which condition for {pk} has almost every multigraph G(n,m)∈ζ(n,m;{pk}) a unique vertex of maximum degree in A? 展开更多
关键词 maximum degree minimum degree degree distribution random bipartite multigraphs
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Permanence and Globally Asymptotic Stability of Cooperative System Incorporating Harvesting 被引量:1
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作者 Fengying Wei Cuiying Li 《Advances in Pure Mathematics》 2013年第7期627-632,共6页
The stability of a kind of cooperative models incorporating harvesting is considered in this paper. By analyzing the characteristic roots of the models and constructing suitable Lyapunov functions, we prove that nonne... The stability of a kind of cooperative models incorporating harvesting is considered in this paper. By analyzing the characteristic roots of the models and constructing suitable Lyapunov functions, we prove that nonnegative equilibrium points of the models are globally asymptotically stable. Further, the corresponding nonautonomous cooperative models have a unique asymptotically periodic solution, which is uniformly asymptotically stable. An example is given to illustrate the effectiveness of our results. 展开更多
关键词 COOPERATIVE System EQUILIBRIUM Stability ASYMPTOTICALLY PERIODIC Solution
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Effects of Solid Matrix and Porosity of Porous Medium on Heat Transfer of Marangoni Boundary Layer Flow Saturated with Power-Law Nanofluids
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作者 陈晖 肖天丽 +1 位作者 陈嘉阳 沈明 《Chinese Physics Letters》 SCIE CAS CSCD 2016年第10期80-84,共5页
The effect of the solid matrix and porosity of the porous medium are first introduced to the study of power-law nanofluids, and the Marangoni boundary layer flow with heat generation is investigated. Two cases of soli... The effect of the solid matrix and porosity of the porous medium are first introduced to the study of power-law nanofluids, and the Marangoni boundary layer flow with heat generation is investigated. Two cases of solid matrix of porous medium including glass balls and aluminum foam are considered. The governing partial differential equations are simplified by dimensionless variables and similarity transformations, and are solved numerically by using a shooting method with the fourth-fifth-order Runge-Kutta integration technique. It is indicated that the increase of the porosity leads to the enhancement of heat transfer in the surface of the Marangoni boundary layer flow. 展开更多
关键词 of is as Effects of Solid Matrix and Porosity of Porous Medium on Heat Transfer of Marangoni Boundary Layer Flow Saturated with Power-Law Nanofluids in with on
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The primitive matrices of sandwich semigroups of generalized circulant Boolean matrices
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作者 LIU Jian-ping CHEN Jin-song 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2013年第3期311-320,共10页
Let Gn(C) be the sandwich semigroup of generalized circulant Boolean matrices with the sandwich matrix C and Gc(Jr~) the set of all primitive matrices in Gn(C). In this paper, some necessary and sufficient condi... Let Gn(C) be the sandwich semigroup of generalized circulant Boolean matrices with the sandwich matrix C and Gc(Jr~) the set of all primitive matrices in Gn(C). In this paper, some necessary and sufficient conditions for A in the semigroup Gn(C) to be primitive are given. We also show that Gc(Jn) is a subsemigroup of Gn(C). 展开更多
关键词 generalized circulant Boolean matrix sandwich semigroup primitive matrix.
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A DFT Study on the Adsorption of CO_2 Molecules on CaO(001) Surface at Different Coverages 被引量:4
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作者 CHEN Hong ZHANG Yong-Fan +3 位作者 LI Yi HUANG Shu-Ping QI Jia-Yuan LIU Rong 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 2019年第1期17-24,1,共9页
The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structu... The CO_2 adsorption on CaO(001) surface at different coverages from 1/9 monolayer(ML) to 1 ML has been investigated using density functional theory calculations. With the analysis of the most stable adsorption structures at different coverages, the mechanism of CaO(001)surface carbonating into CaCO_3 has been explored. At low coverages(≤1/3 ML), CO_2 molecule prefers sitting in parallel pattern on the CaO(001) surface, while the structure of the CaO(001)surface remains unchanged. At medium coverage(4/9 ~ 2/3 ML), the repulsive interactions between oxygen atoms of CO_2 become stronger, and the calcium carbonation structure appears on the CaO(001) surface. At high coverage( ≥ 7/9 ML), the structure of the CaO(001) surface is deeply damaged, and a few CO_2 molecules have penetrated into the surface and bound to the O atom of the second layer(sub-surface), eventually forming the layered structure of CaCO_3.Additionally, herein has discussed the simulation of HREELS and thermodynamical stability of these structures at different coverages. 展开更多
关键词 carbon dioxide CaO(001)surface DFT DIFFERENT coverages
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Generalized Drazin spectrum of operator matrices 被引量:4
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作者 ZHANG Shi-fang ZHONG Huai-jie LIN Li-qiong 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2014年第2期162-170,共9页
Let A ∈ B(X) and B ∈ B(Y), Me be an operator on Banach space X + Y given by Mc =(A C 0 B)A generalized Drazin spectrum defined by σgD(T) = {λ∈C : T-λI is not generalized Drazin invertible} is considere... Let A ∈ B(X) and B ∈ B(Y), Me be an operator on Banach space X + Y given by Mc =(A C 0 B)A generalized Drazin spectrum defined by σgD(T) = {λ∈C : T-λI is not generalized Drazin invertible} is considered in this paper. It is shown that 展开更多
关键词 operator matrices generalized Drazin spectrum filling-in-hole problem.
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The atom-bond connectivity index of chemical bicyclic graphs 被引量:4
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作者 CHEN Jin-song GUO Xiao-feng 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2012年第2期243-252,共10页
The atom-bond connectivity(ABC) index provides a good model for the stability of linear and branched alkanes as well as the strain energy of cycloalkanes,which is defined as ABC(G) =∑ uv∈E(G) √d u+dv-2 dudv,... The atom-bond connectivity(ABC) index provides a good model for the stability of linear and branched alkanes as well as the strain energy of cycloalkanes,which is defined as ABC(G) =∑ uv∈E(G) √d u+dv-2 dudv,where du denotes the degree of a vertex u in G.A chemical graph is a graph in which no vertex has degree greater than 4.In this paper,we obtain the sharp upper and lower bounds on ABC index of chemical bicyclic graphs. 展开更多
关键词 atom-bond connectivity index chemical bicyclic graph bound.
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REMARKS ON BRUALDI'S THEOREM FOR SPECTRUM INCLUSION REGION OF AN IRREDUCIBLE MATRIX 被引量:1
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作者 陈神灿 《Acta Mathematica Scientia》 SCIE CSCD 2005年第1期112-118,共7页
This paper obtains a necessary and sufficient condition for an irreducible complex matrix whose comparison matrix is a singular M-matrix to be singular. This is used to establish a necessary and sufficient condition f... This paper obtains a necessary and sufficient condition for an irreducible complex matrix whose comparison matrix is a singular M-matrix to be singular. This is used to establish a necessary and sufficient condition for a boundary point of Brualdi’s inclusion region of the eigenvalues of an irreducible complex matrix to be an eigenvalue. 展开更多
关键词 M-MATRIX irreducible circuit α-diagonal dominant matrix spectrum inclusion region
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Joint Noise Reduction and lp-Norm Minimization for Enhancing Time Delay Estimation in Colored Noise 被引量:1
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作者 Jingxian Tu Youshen Xia 《Journal of Computer and Communications》 2016年第3期46-53,共8页
Time delay estimation (TDE) is an important issue in signal processing. Conventional TDE algorithms are usually efficient under white noise environments. In this paper, a joint noise reduction and -norm minimization m... Time delay estimation (TDE) is an important issue in signal processing. Conventional TDE algorithms are usually efficient under white noise environments. In this paper, a joint noise reduction and -norm minimization method is presented to enhance TDE in colored noise. An improved subspace method for colored noise reduction is first performed. Then the time delay is estimated by using an -norm minimization method. Because the clean speech signal form the noisy signal is well extracted by noise reduction and the -norm minimization method is robust, the TDE accuracy can be enhanced. Experiment results confirm that the proposed joint estimation method obtains more accurate TDE than several conventional algorithms in colored noise, especially in the case of low signal-to-noise ratio.   展开更多
关键词 Time Delay Estimation Speech Enhancement Noise Reduction SUBSPACE
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Time-Machine Solutions of Einstein's Equations with Electromagnetic Field
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作者 沈明 孙庆有 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第1期69-71,共3页
In this paper we investigate the time-machine problem in the electromagnetic field. Based on a metric which is a more general form of Ori's, we solve the Einstein's equations with the energy-momentum tensors for ele... In this paper we investigate the time-machine problem in the electromagnetic field. Based on a metric which is a more general form of Ori's, we solve the Einstein's equations with the energy-momentum tensors for electromagnetic field, and construct the time-machine solutions, which solve the time machine problem in electromagnetic field. 展开更多
关键词 time-machine solutions closed timelike curves Einstein's equations energy-momentum tensor electromagnetic field energy conditions
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ON GLOBAL BEHAVIOR OF WEAK SOLUTIONS OF COMPRESSIBLE FLOWS OF NEMATIC LIQUID CRYSTALS
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作者 王伟伟 《Acta Mathematica Scientia》 SCIE CSCD 2015年第3期650-672,共23页
In this article, we investigate the global behavior of weak solutions of a simplified Ericksen-Leslie system for compressible flows of nematic liquid crystals in time in a bounded three-dimension domain-arbitrary forc... In this article, we investigate the global behavior of weak solutions of a simplified Ericksen-Leslie system for compressible flows of nematic liquid crystals in time in a bounded three-dimension domain-arbitrary forces. By adapting the arguments for the compressible Navier-Stokes equations, and carefully analyzing the direction field of liquid crystals in the equations of angular momentum, we show the existence of bounded absorbing sets, global bounded trajectories, and global attractors to weak solutions of compressible flows of nematic liquid crystals with the adiabatic constant γ〉5/3. 展开更多
关键词 Liquid crystals weak solutions bounded absorbing set bounded trajectories ATTRACTOR
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Bounds of the Estrada index of graphs
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作者 LIU Jian-ping LIU Bo-lian 《Applied Mathematics(A Journal of Chinese Universities)》 SCIE CSCD 2010年第3期325-330,共6页
Let G be a graph of order n and let λ1, λ2,...,λn be its eigenvalues. The Estrada index[2] of G is defined as EE = EE(G) =∑i=1^n e^λi.In this paper, new bounds for EE are established, as well as some relations ... Let G be a graph of order n and let λ1, λ2,...,λn be its eigenvalues. The Estrada index[2] of G is defined as EE = EE(G) =∑i=1^n e^λi.In this paper, new bounds for EE are established, as well as some relations between EE and graph energy E. 展开更多
关键词 Graph spectrum Estrada index BOUND energy (of graph).
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OMP-BASED MULTI-BAND SIGNAL RECONSTRUCTION FOR ECOLOGICAL SOUNDS RECOGNITION
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作者 Ouyang Zhen Li Ying 《Journal of Electronics(China)》 2014年第1期50-60,共11页
The paper proposes a new method of multi-band signal reconstruction based on Orthogonal Matching Pursuit(OMP),which aims to develop a robust Ecological Sounds Recognition(ESR)system.Firstly,the OMP is employed to spar... The paper proposes a new method of multi-band signal reconstruction based on Orthogonal Matching Pursuit(OMP),which aims to develop a robust Ecological Sounds Recognition(ESR)system.Firstly,the OMP is employed to sparsely decompose the original signal,thus the high correlation components are retained to reconstruct in the first stage.Then,according to the frequency distribution of both foreground sound and background noise,the signal can be compensated by the residual components in the second stage.Via the two-stage reconstruction,high non-stationary noises are effectively reduced,and the reconstruction precision of foreground sound is improved.At recognition stage,we employ deep belief networks to model the composite feature sets extracted from reconstructed signal.The experimental results show that the proposed approach achieved superior recognition performance on 60 classes of ecological sounds in different environments under different Signal-to-Noise Ratio(SNR),compared with the existing method. 展开更多
关键词 Ecological Sounds Recognition(ESR) Multi-band reconstruction Orthogonal Matching Pursuit(OMP) Sparse decomposition Deep belief networks
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One Direction Rough Law Generation and Its Security Transmission
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作者 张凌 陈国龙 《Journal of Donghua University(English Edition)》 EI CAS 2010年第2期209-212,共4页
By using function one direction S-rough sets (function one direction singular rough sets), the concept of one direction rough law is proposed, where one direction rough law is the law pair { w(x)-, w(x) - } comp... By using function one direction S-rough sets (function one direction singular rough sets), the concept of one direction rough law is proposed, where one direction rough law is the law pair { w(x)-, w(x) - } composed by w(x)- and w(x)-, ffthe attribute set {a_ , a-} of function one direction S-rough sets changes, then one direction rough law { w(x)_, w(x)- } will change, too. By employing ellipse curves, the concept of one direction rough law security is presented, the security theorem of one direction rough law is proposed and the applications are given. One direction rough law security, which is generated by the intersection and penetration between function one direction S-rough sets and ellipse curves, is a new applied research direction of function S-rough sets. 展开更多
关键词 one direction rough law elliptic curve security transmission security theorem APPLICATIONS
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Belief and Knowledge Reasoning
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作者 宁正元 赖贤伟 +1 位作者 胡山立 王秀丽 《Journal of Donghua University(English Edition)》 EI CAS 2010年第2期254-257,共4页
Alternating-time Temporal Epistemic Logic (ATEL) which is an important kind of multi-agent cooperation logics only takes knowledge into account,but does not deal with belief of agents. By introducing three kinds of be... Alternating-time Temporal Epistemic Logic (ATEL) which is an important kind of multi-agent cooperation logics only takes knowledge into account,but does not deal with belief of agents. By introducing three kinds of belief operators into ATEL,a new multi-agent cooperation logic named ATBKL (Alternating-time Temporal Belief and Knowledge Logic) was developed. A model checking algorithm was proposed. It is proved that the model checking complexity of ATBKL is the same as that of ATEL,i.e.,the presented logic is better for further study of multi-agent systems. 展开更多
关键词 multi-agent cooperation logic BELIEF KNOWLEDGE
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Benchmarking Algorithms for Gene Set Scoring of Single-cell ATAC-seq Data
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作者 Xi Wang Qiwei Lian +3 位作者 Haoyu Dong Shuo Xu Yaru Su Xiaohui Wu 《Genomics, Proteomics & Bioinformatics》 SCIE CAS CSCD 2024年第2期27-42,共16页
Gene set scoring(GSS)has been routinely conducted for gene expression analysis of bulk or single-cell RNA sequencing(RNA-seq)data,which helps to decipher single-cell heterogeneity and cell type-specific variability by... Gene set scoring(GSS)has been routinely conducted for gene expression analysis of bulk or single-cell RNA sequencing(RNA-seq)data,which helps to decipher single-cell heterogeneity and cell type-specific variability by incorporating prior knowledge from functional gene sets.Single-cell assay for transposase accessible chromatin using sequencing(scATAC-seq)is a powerful technique for interrogating single-cell chromatin-based gene regulation,and genes or gene sets with dynamic regulatory potentials can be regarded as cell type-specific markers as if in single-cell RNA-seq(scRNA-seq).However,there are few GSS tools specifically designed for scATAC-seq,and the applicability and performance of RNA-seq GSS tools on scATAC-seq data remain to be investigated.Here,we systematically benchmarked ten GSS tools,including four bulk RNA-seq tools,five scRNA-seq tools,and one scATAC-seq method.First,using matched scATAC-seq and scRNA-seq datasets,we found that the performance of GSS tools on scATAC-seq data was comparable to that on scRNA-seq,suggesting their applicability to scATAC-seq.Then,the performance of different GSS tools was extensively evaluated using up to ten scATAC-seq datasets.Moreover,we evaluated the impact of gene activity conversion,dropout imputation,and gene set collections on the results of GSS.Results show that dropout imputation can significantly promote the performance of almost all GSS tools,while the impact of gene activity conversion methods or gene set collections on GSS performance is more dependent on GSS tools or datasets.Finally,we provided practical guidelines for choosing appropriate preprocessing methods and GSS tools in different application scenarios. 展开更多
关键词 Single-cell ATAC-seq Gene set scoring Pathway analysis Single-cell RNA-seq BENCHMARK
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Positive Periodic Solutions of a Class of Non-autonomous Single Species Population Model with Delays and Feedback Control 被引量:5
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作者 Feng De CHEN Xiao Xin CHEN +1 位作者 Jin De CAO An Ping CHEN 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2005年第6期1319-1336,共18页
With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, several verifiable criteria are established for the global existence of positive periodic solutions of a class of non-autonomou... With the help of a continuation theorem based on Gaines and Mawhin's coincidence degree, several verifiable criteria are established for the global existence of positive periodic solutions of a class of non-autonomous single species population model with delays (both state-dependent delays and continuous delays) and feedback control. After that, by constructing a suitable Lyapunov functional, sufficient conditions which guarantee the existence of a unique globally asymptotic stable positive periodic solution of a kind of nonlinear feedback control ecosystem are obtained. Our results extend and improve the existing results, and have further applications in population dynamics. 展开更多
关键词 Positive periodic solutions DELAYS Coincidence degree Single species model
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Browder Spectra and Essential Spectra of Operator Matrices 被引量:5
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作者 Yun Nan ZHANG Huai Jie ZHONG Li Qiong LIN 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2008年第6期947-954,共8页
Let Mc = ( A0CB ) be a 2 × 2 upper triangular operator matrix acting on the Banach space X × Y. We prove that σr(A) ∪ σr( B)= σr (Mc) ∪ W ,where W is the union of certain of the holes in σr(Mc... Let Mc = ( A0CB ) be a 2 × 2 upper triangular operator matrix acting on the Banach space X × Y. We prove that σr(A) ∪ σr( B)= σr (Mc) ∪ W ,where W is the union of certain of the holes in σr(Mc) which happen to be subsets of σr(A) ∩ σr(B), and σr(A), σr(B), σr(Mc) can be equal to the Browder or essential spectra of A, B, Mc, respectively. We also show that the above result isn't true for the Kato spectrum, left (right) essential spectrum and left (right) spectrum. 展开更多
关键词 Banach space operator matrices Browder spectra essential spectra
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DECAY ESTIMATES FOR ISENTROPIC COMPRESSIBLE MAGNETOHYDRODYNAMIC EQUATIONS IN BOUNDED DOMAIN 被引量:4
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作者 Mohamed Ahmed Abdallah 江飞 谭忠 《Acta Mathematica Scientia》 SCIE CSCD 2012年第6期2211-2220,共10页
In this paper, under the hypothesis that y is upper bounded, we construct a Lyapunov functional for the multidimensional isentropic compressible magnetohydrodynamic equations and show that the weak solutions decay exp... In this paper, under the hypothesis that y is upper bounded, we construct a Lyapunov functional for the multidimensional isentropic compressible magnetohydrodynamic equations and show that the weak solutions decay exponentially to the equilibrium state in L2 norm. Our result verifies that the method of Daoyuan Fang, Ruizhao Zi and Ting Zhang I1] can be adapted to magnetohydrodynamic equations. 展开更多
关键词 Navier-Stokes equations weak solution decay estimates magnetohydrody-namic
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