期刊文献+
共找到12篇文章
< 1 >
每页显示 20 50 100
High-precision downward continuation of potential fi elds algorithm utilizing adaptive damping coeffi cient of generalized minimal residuals 被引量:1
1
作者 Zhang Zhi-Hou Liao Xiao-Long +6 位作者 Shi Ze-Yu Lowry Anthony R. Yao Yu Lu Run-Qi Fan Xiang-Tai Liu Peng-Fei Zhao Si-Wei 《Applied Geophysics》 SCIE CSCD 2020年第5期672-686,900,共16页
The downward continuation of potential fields is a process of calculating their values in a lower plane based on those of a certain plane.This technology is not only a data processing method for resource exploration b... The downward continuation of potential fields is a process of calculating their values in a lower plane based on those of a certain plane.This technology is not only a data processing method for resource exploration but also plays an extremely important role in military applications.However,the downward continuation of potential fields is a typical linear inverse problem that is ill-posed.Generalized minimal residuals(GMRES)is an eff ective solution to ill-posed inverse problems,but it is unstable under the condition wherein the GMRES is directly applied in the calculation process.Moreover,the long-term behavior of its iterative computation is a disordered,divergent result.Therefore,to obtain stable solutions,GMRES is applied to solve the normal equations of the downward continuation of potential fields;it is also used to prequalify for occasional interruptions in the operation process by adding the damping coefficient,thus strengthening the stability conditions of the equations of residual minimization.Finally,the stable downward continuation of the potential fields method is proposed.As indicated by the theoretical data and the measured testing data,the method proposed in this paper has the advantages of high-precision and excellent stability.Furthermore,compared with the Tikhonov iteration method,the proposed method avoids the need to choose regularization parameters. 展开更多
关键词 Potential fi elds generalized minimal residual method high precision and stable downward continuation
下载PDF
Two-Parameter Block Triangular Splitting Preconditioner for Block Two-by-Two Linear Systems
2
作者 Bo Wu Xingbao Gao 《Communications on Applied Mathematics and Computation》 EI 2023年第4期1601-1615,共15页
This paper proposes a two-parameter block triangular splitting(TPTS)preconditioner for the general block two-by-two linear systems.The eigenvalues of the corresponding preconditioned matrix are proved to cluster aroun... This paper proposes a two-parameter block triangular splitting(TPTS)preconditioner for the general block two-by-two linear systems.The eigenvalues of the corresponding preconditioned matrix are proved to cluster around 0 or 1 under mild conditions.The limited numerical results show that the TPTS preconditioner is more efficient than the classic block-diagonal and block-triangular preconditioners when applied to the flexible generalized minimal residual(FGMRES)method. 展开更多
关键词 Block triangular splitting Block two-by-two linear systems Eigenvalues PRECONDITIONER flexible generalized minimal residual(FGMRES)
下载PDF
CYCLIC CODES OVER THE RING Z(_P^2) OF LENGTH p^e 被引量:3
3
作者 Shi Minjia Zhu Shixin 《Journal of Electronics(China)》 2008年第5期636-640,共5页
The study of cyclic codes over rings has generated a lot of public interest.In this paper,we study cyclic codes and their dual codes over the ring Z P2 of length pe,and find a set of generators for these codes.The ran... The study of cyclic codes over rings has generated a lot of public interest.In this paper,we study cyclic codes and their dual codes over the ring Z P2 of length pe,and find a set of generators for these codes.The ranks and minimal generator sets of these codes are studied as well,which play an important role in decoding and determining the distance distribution of codes. 展开更多
关键词 Cyclic code RANK minimal generator set
下载PDF
THE RANKS OF CYCLIC AND NEGACYCLIC CODES OVER THE FINITE RING R 被引量:9
4
作者 Zhu Shixin Shi Minjia 《Journal of Electronics(China)》 2008年第1期97-101,共5页
The ranks of cyclic and negacyclic codes over the finite chain ring R as well as their minimal generating sets are defined, and then the expression forms we presented by studying the structures of cyclic and negacycli... The ranks of cyclic and negacyclic codes over the finite chain ring R as well as their minimal generating sets are defined, and then the expression forms we presented by studying the structures of cyclic and negacyclic codes over the finite chain ring R. Through the paper, it is assumed that the length of codes n can not be divided by the characteristic of R. 展开更多
关键词 Cyclic code RANK minimal generating set
下载PDF
Jacobian-free Newton-Krylov subspace method with wavelet-based preconditioner for analysis of transient elastohydrodynamic lubrication problems with surface asperities 被引量:1
5
作者 N.M.BUJURKE M.H.KANTLI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第6期881-898,共18页
This paper presents an investigation into the effect of surface asperities on the over-rolling of bearing surfaces in transient elastohydrodynamic lubrication(EHL) line contact. The governing equations are discretized... This paper presents an investigation into the effect of surface asperities on the over-rolling of bearing surfaces in transient elastohydrodynamic lubrication(EHL) line contact. The governing equations are discretized by the finite difference method. The resulting nonlinear system of algebraic equations is solved by the Jacobian-free Newtongeneralized minimal residual(GMRES) from the Krylov subspace method(KSM). The acceleration of the GMRES iteration is accomplished by a wavelet-based preconditioner.The profiles of the lubricant pressure and film thickness are obtained at each time step when the indented surface moves through the contact region. The prediction of pressure as a function of time provides an insight into the understanding of fatigue life of bearings.The analysis confirms the need for the time-dependent approach of EHL problems with surface asperities. This method requires less storage and yields an accurate solution with much coarser grids. It is stable, efficient, allows a larger time step, and covers a wide range of parameters of interest. 展开更多
关键词 transient elastohydrodynamic lubrication(EHL) surface roughness bearing Newton-Krylov method generalized minimal residual(GMRES) wavelet preconditioner
下载PDF
PARALLEL MINIMIZATION ALGORITHMS by GENERALIZED SUBDIFFERENTIABILITY
6
作者 C. Sutti A. Peretti(Istituto di Matematica, Facolta di Economia e Commercio, Universita di Verona, Italy) 《Wuhan University Journal of Natural Sciences》 CAS 1996年第Z1期531-540,共10页
Abstract Recently a, monotone generalized directional derixrative has been introduced for Lipschitz functions. This concept has been applied to represent and optimize nonsmooth functions. The second a.pplication resul... Abstract Recently a, monotone generalized directional derixrative has been introduced for Lipschitz functions. This concept has been applied to represent and optimize nonsmooth functions. The second a.pplication result,ed relevant for parallel computing, by allowing to define minimization algorithms with high degree of inherent parallelism. The paper presents first the theoretical background, namely the notions of monotone generalized directional derivative and monotone generalized subdifferential. Then it defines the tools for the procedures, that is a necessary optimality condition and a steel>est descent direction. Therefore the minimization algorithms are outlined. Successively the used architectures and the performed numerical expertence are described, by listing and commenting the t.ested functions and the obtained results. 展开更多
关键词 PARALLEL MINIMIZATION ALGORITHMS by GENERALIZED SUBDIFFERENTIABILITY
下载PDF
<i>Ab-Initio</i>Self-Consistent Density Functional Theory Description of Rock-Salt Magnesium Selenide (MgSe)
7
作者 Blaise Awola Ayirizia Yuriy Malozovsky +2 位作者 Lashounda Franklin Uttam Bhandari Diola Bagayoko 《Materials Sciences and Applications》 2020年第7期401-414,共14页
We report results on electronic, transport, and bulk properties of rock-salt magnesium selenide (MgSe), from density functional theory (DFT) calculations. We utilized a local density approximation (LDA) potential and ... We report results on electronic, transport, and bulk properties of rock-salt magnesium selenide (MgSe), from density functional theory (DFT) calculations. We utilized a local density approximation (LDA) potential and the linear combination of atomic orbitals formalism (LCAO). We followed the Bagayoko, Zhao, and Williams (BZW) method, as enhanced by Ekuma and Franklin (BZW-EF), to perform a generalized minimization of the energy, down to the actual ground state of the material. We describe the successive, self-consistent calculations, with augmented basis sets, that are needed for this generalized minimization. Due to the generalized minimization, our results have the full, physical content of DFT, as per the second DFT theorem [AIP Advances, 4, 127104 (2014)]. Our calculated, indirect bandgap of 2.49 eV, for a room temperature lattice constant of 5.460 <span style="white-space:nowrap;">&Aring;</span>, agrees with experimental findings. We present the ground-state band structure, the related total and partial densities of states, DOS and PDOS, respectively, and electron and hole effective masses for the material. Our calculated bulk modulus of 63.1 GPa is in excellent agreement with the experimental value of 62.8 ± 1.6 GPa. Our predicted equilibrium lattice constant, at zero temperature, is 5.424 <span style="white-space:nowrap;">&Aring;</span>, with a corresponding indirect bandgap of 2.51 eV. We discuss the reasons for the agreements between our findings and available, corresponding, experimental ones, particularly for the band gap, unlike the previous DFT results obtained with ab-initio LDA or GGA potentials. 展开更多
关键词 Density Functional Theory Generalized Energy Minimization Ground State Band Structure Band Gap Related Properties
下载PDF
Projection Improved SPAI Preconditioner for FGMRES
8
作者 Mingguang Geng Shuli Sun 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE CSCD 2023年第4期1035-1052,共18页
Krylov subspace methods are widely used for solving sparse linear algebraic equations,but they rely heavily on preconditioners,and it is difficult to find an effective preconditioner that is efficient and stable for a... Krylov subspace methods are widely used for solving sparse linear algebraic equations,but they rely heavily on preconditioners,and it is difficult to find an effective preconditioner that is efficient and stable for all problems.In this paper,a novel projection strategy including the orthogonal and the oblique projection is proposed to improve the preconditioner,which can enhance the efficiency and stability of iteration.The proposed strategy can be considered as a minimization process,where the orthogonal projection minimizes the energy norm of error and the oblique projection minimizes the 2-norm of the residual,meanwhile they can be regarded as approaches to correct the approximation by solving low-rank inverse of the matrices.The strategy is a wide-ranging approach and provides a way to transform the constant preconditioner into a variable one.The paper discusses in detail the projection strategy for sparse approximate inverse(SPAI)preconditioner applied to flexible GMRES and conducts the numerical test for problems from different applications.The results show that the proposed projection strategy can significantly improve the solving process,especially for some non-converging and slowly convergence systems. 展开更多
关键词 Generalized minimal residual PRECONDITIONER sparse approximate inverse oblique projection orthogonal projection
原文传递
On Finite Noncommutative Grobner Bases
9
作者 Yatma Diop Djiby Sow 《Algebra Colloquium》 SCIE CSCD 2020年第3期381-388,共8页
It is well known that in the noncommutative polynomial ring in serveral variables Buchberger's algorithm does not always terminate.Thus,it is important to characterize noncommutative ideals that admit a finite Gro... It is well known that in the noncommutative polynomial ring in serveral variables Buchberger's algorithm does not always terminate.Thus,it is important to characterize noncommutative ideals that admit a finite Grobner basis.In this context,Eisenbud,Peeva and Sturmfels defined a mapγfrom the noncommutative polynomial ring k〈X_(1),...,X_(n)〉to the commutative one k[x_(1),...,x_(n)]and proved that any ideal J of k〈X_(1),...,X_(n)〉,written as J=γ^(-1)(L)for some ideal L of k[x_(1),...,x_(n)],amits a finite Grobner basis with respect to a special monomial ordering on k〈X_(1),...,X_(n)〉.In this work,we approach the opposite problem.We prove that under some conditions,any ideal J of k〈X_(1),...,X_(n)〉admitting a finite Grobner basis can be written as J=γ^(-1)(L)for some ideal L of k[x_(1),...,x_(n)]. 展开更多
关键词 natural maps lexicographic extension minimal generators COMMUTATORS
原文传递
Mathematical Programming Solution for the Frictional Contact Multipole BEM 被引量:8
10
作者 于春肖 申光宪 刘德义 《Tsinghua Science and Technology》 SCIE EI CAS 2005年第1期51-56,共6页
This paper presents a new mathematical model for the highly nonlinear problem of frictional con- tact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic con- tact with frict... This paper presents a new mathematical model for the highly nonlinear problem of frictional con- tact. A programming model, multipole boundary element method (BEM), was developed for 3-D elastic con- tact with friction to replace the Monte Carlo method. A numerical example shows that the optimization pro- gramming model for the point-to-surface contact with friction and the fast optimization generalized minimal residual algorithm (GMRES(m)) significantly improve the analysis of such problems relative to the conven- tional BEM. 展开更多
关键词 nonlinear programming generalized minimal residual algorithm (GMRES(m)) point-to-surface contact multipole boundary element method
原文传递
Commutative Rings Whose Zero-divisor Graph Is a Proper Refinement of a Star Graph 被引量:3
11
作者 Qiong LIU Tong Suo WU 《Acta Mathematica Sinica,English Series》 SCIE CSCD 2011年第6期1221-1232,共12页
A graph is called a proper refinement of a star graph if it is a refinement of a star graph, but it is neither a star graph nor a complete graph. For a refinement of a star graph G with center c, let G* be the subgra... A graph is called a proper refinement of a star graph if it is a refinement of a star graph, but it is neither a star graph nor a complete graph. For a refinement of a star graph G with center c, let G* be the subgraph of G induced on the vertex set V(G) / {c or end vertices adjacent to c}. In this paper, we study the isomorphic classification of some finite commutative local rings R by investigating their zero-divisor graphs G=Г(R), which is a proper refinement of a star graph with exactly one center c. We determine all finite commutative local rings R such that G* has at least two connected components. We prove that the diameter of the induced graph G* is two if Z(R)2 ≠{0}, Z(R)3 = {0} and Gc is connected. We determine the structure of R which has two distinct nonadjacent vertices a, fl C Z(R)*/{c} such that the ideal [N(a)N(β)]{0} is generated by only one element of Z(R)*/{c}. We also completely determine the correspondence between commutative rings and finite complete graphs Kn with some end vertices adjacent to a single vertex of Kn. 展开更多
关键词 Commutative rings zero-divisor graph minimal generating set connected component
原文传递
Efficient and Accurate Numerical Methods Using the Accelerated Spectral Deferred Correction for Solving Fractional Differential Equations
12
作者 Xuejuan Chen Zhiping Mao George Em Karniadakis 《Numerical Mathematics(Theory,Methods and Applications)》 SCIE CSCD 2022年第4期876-902,共27页
We develop an efficient and accurate spectral deferred correction(SDC)method for fractional differential equations(FDEs)by extending the algorithm in[14]for classical ordinary differential equations(ODEs).Specifically... We develop an efficient and accurate spectral deferred correction(SDC)method for fractional differential equations(FDEs)by extending the algorithm in[14]for classical ordinary differential equations(ODEs).Specifically,we discretize the resulted Picard integral equation by the SDC method and accelerate the convergence of the SDC iteration by using the generalized minimal residual algorithm(GMRES).We first derive the correction matrix of the SDC method for FDEs and analyze the convergence region of the SDC method.We then present several numerical examples for stiff and non-stiff FDEs including fractional linear and nonlinear ODEs as well as fractional phase field models,demonstrating that the accelerated SDC method is much more efficient than the original SDC method,especially for stiff problems.Furthermore,we resolve the issue of low accuracy arising from the singularity of the solutions by using a geometric mesh,leading to highly accurate solutions compared to uniform mesh solutions at almost the same computational cost.Moreover,for long-time integration of FDEs,using the geometric mesh leads to great computational savings as the total number of degrees of freedom required is relatively small. 展开更多
关键词 Stiff problem generalized minimal residual geometric mesh refinement long time evolution fractional phase field models
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部