检索结果-南通市图书馆

Lipschitz continuity of best approximations and Chebyshev centers

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第3期43卷 185-188页

作者： LI Chong 1 and WANG Xinghua 2.1. Center for Mathematical Sciences, zhejiang university, hangzhou 31002., China 2. D{2. of mathematics, hangzhou university, hangzhou 31002., China Center for Mathematical Sciences Zhejiang University Hangzhou China Department of mathematics Hangzhou University Hangzhou China

The Lipschitz continuity results are given for best approximations and Chebyshev centers. Consequently, the open problem presented by Septycki and Vleck is solved completely.

关键词： best approximation Chebyshev center uniform convexity.

Perturbations of the radical of nest algebras

在线全文

学校读者我要写书评

暂无评论

Chinese Science Bulletin 1998年第7期43卷 556-560页

作者： LU Fangyan 1 and LU Shijie 2.1. Department of mathematics, Suzhou {2., Suzhou 2.5006, China 2. Department of mathematics, zhejiang university, hangzhou 31002., China Department of mathematics Suzhou University Suzhou China Department of mathematics Zhejiang University Hangzhou China

Let R N and K-N be the radical ideal and the compact operator ideal of nest algebra T(N) respectively. It is proved thatR-N+K-N=span{T∈T(N)∶TT(N)NCT}=span{T∈T(N): #σ′(ST)≤1, S∈T(N)}.

关键词： nest algebras radical perturbation.

Online uniform machine covering with the known largest size

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第11期17卷 1271-1278页

作者： Cao Shunjuan1,2.and Tan Zhiyi1,3(1. Department of mathematics, {2., hangzhou 31002., China 2. Department of mathematics, zhejiang Forestry university, hangzhou 311300, China 3. State Key Laboratory of CAD & CG, {2., hangzhou 31002., China) Department of mathematics Zhejiang University Hangzhou 310027 China Department of mathematics Zhejiang Forestry University Hangzhou 311300 China State Key Laboratory of CAD & CG Zhejiang University Hangzhou 310027 China

This paper investigates the semi-online scheduling problem with the known largest size on two uniform machines. The objective is to maximize the minimum machine completion time. Both lower bounds and algorithms are given. Algorithms are optimal for the majority values of s≥1, where s is the speed ratio of the two machines. The largest gap between the competitive ratio and the lower bound is about 0.064. Moreover, the overall competitive ratio 2.matches the overall lower bound.

关键词： scheduling and covering uniform machine design and analysis of algorithm online competitive ratio

Planar cubic hybrid hyperbolic polynomial curve and its shape classification

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2004年第1期14卷 42-47页

作者： WANG Guozhao 1,2. * and YANG Qinmin 1,2. (1. Institute of Computer Graphics and Image Processing, 2. Department of mathematics, {2., hangzhou 31002., China) zhejiang Univ Inst Comp Graph & Image Proc Hangzhou 310027 Peoples R China zhejiang Univ Dept Math Hangzhou 310027 Peoples R China

The planar cubic hybrid hyperbolic polynomial curves and cubic H Bézier curves are presented. The conditions leading to inflection points and singularities (cusps and loops) are investigated and the shape of these curves is classified. The conclusions enable us to detect inflection points and singularities and get an idea of how to preserve the fair shape when designing such curves.

关键词： hybrid hyperbolic polynomial curve H-Bézier curve shape classification inflection points singularities

Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets

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 2007年第11期50卷 1537-1551页

作者： Li-feng XI~(1+) Huo-jun RUAN~2.1 Institute of mathematics,zhejiang Wanli {2.,Ningbo 315100,China 2.Department of mathematics,zhejiang university,hangzhou 31002.,China Institute of mathematics Zhejiang Wanli University Ningbo 315100 China Department of mathematics Zhejiang University Hangzhou 310027 China

This paper investigates the Lipschitz equivalence of generalized {1,3,5}-{1,4,5} self-similar sets D=(r_1D)∪(r_2.+(1+r_1-r_2.r_3)/2.∪(r_3D+1+r_3) and E=(r_1E)∪(r_2.+1-r_2. r_3)∪(r_3E+1-r_3),and proves that D and E... 详细信息

关键词： self-similar set overlap Lipschitz equivalence graph-directed construction ergodicity martingale

Electro-mechanical response of functionally graded beams with imperfectly integrated surface piezoelectric layers

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2006年第5期49卷 513-525页

作者： YAN Wei1 & CHEN Weiqiu1,2.1. Department of Civil Engineering, zhejiang university, {2., China 2. State Key Lab of CAD & CG, zhejiang university, {2., China 1. Department of Civil Engineering Zhejiang University Hangzhou 310027 China 2. State Key Lab of CAD & CG Zhejiang University Hangzhou 310027 China

The time-dependent behavior of a simply-supported functionally graded beam bonded with piezoelectric sensors and actuators is studied using the state-space method. The creep behavior of bonding adhesives between piezoelectric layers and beam is characterized by a Kelvin-Voigt viscoelastic model, which is practical in a high temperature circumstance. Both the host elastic functionally graded beam and the piezoelectric layers are orthotropic and in a state of plane stress, with the former being inhomogeneous along the thickness direction. A laminate model is employed to approximate the host beam. Moreover, the coupling effect between the elastic deformation and electric field in piezoelectric layers is considered. Results indicate that the viscoelastic property of interfacial adhesives has a significant effect on the function of bonded actuators and sensors with time elapsing.

关键词： functionally graded beam piezoelectric layers Kelvin-Voigt model state-space method

Constrained Bézier curves' best multi-degree reduction in the L2.norm

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2005年第9期15卷 843-850页

作者： ZHANG Renjiang 1,2.** and WANG Guojin1(1. Institute of Computer Images and Graphics, zhejiang university, hangzhou 31002., China 2. China Institute of Metrology, {2., hangzhou 310034, China) Institute of Computer Images and Graphics Zhejiang University Hangzhou 310027 China. State Key Laboratory of CAD&CG Zhejiang University Hangzhou 310027 China. China Institute of Metrology Zhejiang Hangzhou 310034 China

In computer aided geometric design, the degree reduction of the parameter curve is a key technique in data exchange and data compression. The various existing methods of degree reduction cannot decide whether the degree reduction curve satisfying the given tolerance exists beforehand, cannot give approximation of the best multi-degree reduction, or cannot provide explicit expression and error formula of the degree reduction curve. In this paper, we propose an entirely new method, which can hurdle the above flaws completely. For a given Bézier curve of degree n, we can easily decide whether a Bézier reduction curve of degree m exists, which has equal derivatives with the given curve up to （r-1）-th and （s-1）-th orders （r,s≤m） respectively at the endpoints, so the approximating error is less than the given tolerance ε in the L2.norm. If the curve exists, the explicit expression can be given.

关键词： computer aided design Bézier curve degree reduction L2.norm tolerance.

Ordinal scheduling problem and its asymptotically optimal algorithms on parallel machine system

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 in China(Series F) 2004年第2期47卷 161-169页

作者： TAN Zhiyi1,2.& HE Yong1 1. Department of mathematics, {2., hangzhou 31002., China (email: tanzy@math.zju. *** heyong@math.zju.***) 2. State Key Laboratory of CAD & CG, {2., hangzhou 31002., China 1. Department of mathematics Zhejiang University 310027 Hangzhou China 2. State Key Laboratory of CAD & CG Zhejiang University 310027 Hangzhou China

Focusing on the ordinal scheduling problem on a parallel machine system, we discuss the background of ordinal scheduling and the motivation of ordinal algorithms. In addition, for the ordinal scheduling problem on identical parallel machines with the objective to maximize the minimum machine load, we then give two asymptotically optimal algorithm classes which have worst-case ratios very close to the upper bound of the problem for any given m. These results greatly improve the results proposed by He Yong and Tan Zhiyi in 2.02.

关键词： scheduling design and analysis of algorithm worst-case ratio.

Interpolating triangular meshes by Loop subdivision scheme

在线全文

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2010年第9期53卷 1765-1773页

作者： DENG ChongYang1* & WANG GuoZhao2.1Institute of Applied mathematics and Engineering Computations,hangzhou Dianzi {2.,hangzhou 310018,China 2.epartment of mathematics,zhejiang university,hangzhou 31002.,China 1. Institute of Applied mathematics and Engineering Computations Hangzhou Dianzi University Hangzhou 310018 China2. Department of Mathematics Zhejiang University Hangzhou 310027 China

Using the limit point formula of the Loop subdivision scheme,we propose a very simple and efficient method for constructing interpolation surface of triangular meshes by Loop subdivision *** excellent properties of the method are:(1) Locality:the perturbation of a given vertex only influences the surface shape near this vertex.(2. Efficiency:the locations of new points can be computed with explicit formulae.(3) Easiness in implementation:only the geometric rule of the first step should be modified.(4) Freedom:for each edge,there is one degree of freedom to adjust the shape of the interpolation surface.(5) Easiness in generalization:it is easy to generalize our method to other approximation subdivision schemes with explicit formulae to compute limit point.

关键词： computer aided geometric design subdivision surface approximating subdivision scheme Loop surface surface interpolating