检索结果-南通市图书馆

STRUCTURED CONDITION NUMBERS FOR THE TIKHONOV REGULARIZATION OF DISCRETE ILL-POSED PROBLEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2017年第2期35卷 169-186页

作者： LingshengMeng bing zheng School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China

The possibly most popular regularization method for solving the least squares problem rain ‖Ax - b‖2 with a highly ill-conditioned or rank deficient coefficient matrix A is the x Tikhonov regularization method. In this paper we present the explicit expressions of the normwise, mixed and componentwise condition numbers for the Tikhonov regularization when A has linear structures. The structured condition numbers in the special cases of nonlinear structure i.e. Vandermonde and Cauchy matrices are also considered. Some comparisons between structured condition numbers and unstructured condition numbers are made by numerical experiments. In addition, we also derive the normwise, mixed and componentwise condition numbers for the Tikhonov regularization when the coefficient matrix, regularization matrix and right-hand side vector are all perturbed, which generalize the results obtained by Chu et al. [Numer. Linear Algebra Appl., 18 （2011）, 87-103].

关键词： Tikhonov regularization Discrete ill-posed problem Structured least squaresproblem Structured condition number.

Estimation of the Misclassification Error for Multicategory Support Vector Machine Classification

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 2008年第3期24卷 511-528页

作者： bing zheng LI Department of Mathematics Zhejiang University Hangzhou 310028 P. R. China

The purpose of this paper is to provide an error analysis for the multicategory support vector machine （MSVM） classificaton problems. We establish the uniform convergency approach for MSVMs and estimate the misclassification error. The main difficulty we overcome here is to bound the offset vector. As a result, we confirm that the MSVM classification algorithm with polynomial kernels is always efficient when the degree of the kernel polynomial is large enough. Finally the rate of convergence and examples are given to demonstrate the main results.

关键词： multicategory support vector machine classifier misclassification error reproducing kernel Hilbert space approximation error

Tensor Product of Massey Products

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2006年第1期22卷 13-22页

作者： Qi bing zheng Department of Mathematics Nankai University Tianjin 300071 P. R. China

In this paper, we interpret Massey products in terms of realizations （twitsting cochains） of certain differential graded coalgebras with values in differential graded algebras. In the case where the target algebra is the cobar construction of a differential graded commutative Hopf algebra, we construct the tensor product of realizations and show that the tensor product is strictly associative, and commutative up to homotopy.

关键词： Realization Hopf algebra

THE GENERALIZED LOCAL HERMITIAN AND SKEW-HERMITIAN SPLITTING ITERATION METHODS FOR THE NON-HERMITIAN GENERALIZED SADDLE POINT PROBLEMS

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

Journal of Computational Mathematics 2014年第3期32卷 312-331页

作者： Hongtao Fan bing zheng School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China

For large and sparse saddle point problems, Zhu studied a class of generalized local Hermitian and skew-Hermitian splitting iteration methods for non-Hermitian saddle point problem [M.-Z. Zhu, Appl. Math. Comput. 218 （2012） 8816-8824 ]. In this paper, we further investigate the generalized local Hermitian and skew-Hermitian splitting （GLHSS） iteration methods for solving non-Hermitian generalized saddle point problems. With different choices of the parameter matrices, we derive conditions for guaranteeing the con- vergence of these iterative methods. Numerical experiments are presented to illustrate the effectiveness of our GLHSS iteration methods as well as the preconditioners.

关键词： Generalized saddle point problems Hermitian and skew-Hermitian matrixsplitting Iteration method Convergence.

Aggregated morphodynamic modelling of tidal inlets and estuaries

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

Water Science and Engineering 2020年第1期13卷 1-13页

作者： zheng bing Wang Ian Townend Marcel Stive Faculty of Civil Engineering and Geosciences Delft University of TechnologyDelft 2600 GAthe Netherlands College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Unit of Marine and Coastal Systems DeltaresDelft 2600 MHthe Netherlands School of Ocean and Earth Sciences University of SouthamptonSouthampton SO143ZHUK

Aggregation is used to represent the real world in a model at an appropriate level of *** used the convection-diffusion equation to examine the implications of aggregation progressing from a three-dimensional(3D)spatial description to a model representing a system as a single box that exchanges sediment with the adjacent *** highlight how all models depend on some forms of parametric closure,which need to be chosen to suit the scale of aggregation adopted in the *** such models are therefore aggregated and make use of some empirical relationships to deal with sub-scale *** such appropriately aggregated model,the model for the aggregated scale morphological interaction between tidal basin and adjacent coast(ASMITA),is examined in more detail and used to illustrate the insight that this level of aggregation can bring to a problem by considering how tidal inlets and estuaries are impacted by sea level rise.

关键词： Tidal inlet and estuary Morphodynamic modelling Aggregation Temporal and spatial scales Sea level rise Sediment transport

Exploratory study of logistics service quality scale based on online shopping malls

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第6期8卷 926-931页

作者： FENG Yi-xiong zheng bing TAN Jian-rong State Key Lab. of CAD ＆ CG Zhejiang University Hangzhou 310027 China College of Economics ＆ Management Dalian University Dalian 116622 China

Online shopping has already become the new mode that a lot of customers try to adopt. At the same time, the online shopping could not be successfully completed without logistics service. Logistics service quality (LSQ) has significant impact on revenue and profitability. This paper presents the issue from the perspective of the customer, and explores the initial factors of LSQ based on the online shopping through in-depth interview and the Delphi method. The survey uses a standard 7-point Likert-type scale to measure the LSQ. Empirical research results are shown in detail to confirm seven LSQ dimensions with Chinese characteristics, including timeliness quality, personal contact quality, order quality, order discrepancy handling, order condition and convenience. Statistical analyses of the investigation were conducted to test the reliability and validity of the LSQ evaluation model.

关键词： Online shopping Logistics service Logistics service quality (LSQ) Dimensions of LSQ

Development and Extension of An Aggregated Scale Model: Part 1–Background to ASMITA

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2016年第4期30卷 483-504页

作者： Ian TOWNEND zheng bing WANG Marcel STIVE Zeng ZHOU University of Southampton Southampton S0171B JUK TU Delfl Delft 2600.44The Netherlands Deltares Delft 2600 MHThe Netherlands Jiangsu Key Laboratory of Coast Ocean Resources Development and Environment Security Hohai UniversityNanjing 210098China

Whilst much attention has been given to models that describe wave, tide and sediment transport processes in sufficient detail to determine the local changes in bed level over a relatively detailed representation of the bathymetry, far less attention has been given to models that consider the problem at a much larger scale （e.g. that of geomorphological elements such as a tidal fiat and tidal channel）. Such aggregated or lumped models tend not to represent the processes in detail but rather capture the behaviour at the scale of interest. One such model developed using the concept of an equilibrium concentration is the Aggregated Scale Morphological Interaction between Tidal basin and Adjacent coast （ASMITA）. In this paper we provide some new insights into the concepts of equilibrium, and horizontal and vertical exchange that are key components of this modelling approach. In a companion paper, we summarise a range of developments that have been undertaken to extend the original model concept, to illustrate the flexibility and power of the conceptual framework. However, adding detail progressively moves the model in the direction of the more detailed process-based models and we give some consideration to the boundary between the two.

关键词： estuary tidal inlet morphology tides waves sediment transport

ON CONTRACTION AND SEMI-CONTRACTION FACTORS OF GSOR METHOD FOR AUGMENTED LINEAR SYSTEMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2010年第6期28卷 901-912页

作者： Fang Chen Yao-Lin Jiang bing zheng Department of Mathematical Sciences Xi'an Jiaotong University Xi'an 710049 China School of Science Xi'an University of Post and Telecommunications Xi'an 710121 China Department of Mathematical Sciences Xi ' an Jiaotong University Xi ' an 710049 China School of Mathematics and Statistics Lanzhou University Lanzhou 730000 China

The generalized successive overrelaxation （GSOR） method was presented and studied by Bai, Parlett and Wang [Numer. Math. 102（2005）, pp.1-38] for solving the augmented system of linear equations, and the optimal iteration parameters and the corresponding optimal convergence factor were exactly obtained. In this paper, we further estimate the contraction and the semi-contraction factors of the GSOR method. The motivation of the study is that the convergence speed of an iteration method is actually decided by the contraction factor but not by the spectral radius in finite-step iteration computations. For the nonsingular augmented linear system, under some restrictions we obtain the contraction domain of the parameters involved, which guarantees that the contraction factor of the GSOR method is less than one. For the singular but consistent augmented linear system, we also obtain the semi-contraction domain of the parameters in a similar fashion. Finally, we use two numerical examples to verify the theoretical results and the effectiveness of the GSOR method.

关键词： Contraction and semi-contraction factors, Augmented linear system, GSOR method Convergence.

Development and Extension of An Aggregated Scale Model:Part 2-Extensions to ASMITA

在线全文

学校读者我要写书评

暂无评论

China Ocean Engineering 2016年第5期30卷 651-670页

作者： Ian TOWNEND zheng bing WANG Marcel STIVE Zeng ZHOU University of Southampton Southampton S0171B JUK TU Delft Delft 2600 AAThe Netherlands Deltares Delft 2600 MHThe Netherlands Jiangsu Key Laboratory of Coast Ocean Resources Development and Environment Security Hohai UniversityNanjing 210098China

Whilst much attention has been given to models that describe wave, tide and sediment transport processes in sufficient detail to determine the local changes in bed level over a relatively detailed representation of the bathymetry, far less attention has been given to models that consider the problem at a much larger scale （e.g. that of geomorphological elements such as a tidal flat and tidal channel）. Such aggregated or lumped models tend not to represent the processes in detail but rather capture the behaviour at the scale of interest. One such model developed using the concept of an equilibrium concentration is the Aggregated Scale Morphological Interaction between Tidal basin and Adjacent coast （ASMITA）. In a companion paper （Part 1）, we detail the original model and provide some new insights into the concepts of equilibrium, and horizontal and vertical exchange that are key components of this modelling approach. In this paper, we summarise a range of developments that have been undertaken to extend the original model concept, to illustrate the flexibility and power of the conceptual framework. However, adding detail progressively moves the model in the direction of the more detailed process-based models and we give some consideration to the boundary between the two.

关键词： estuary tidal inlet morphology tides waves sediment transport