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Weight hierarchies of linear codes satisfying the Near-Chain condition

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Progress in Natural Science:Materials International 2005年第9期15卷 784-792页

作者： LIU Zihui1** and CHEN Wende2(1. school of mathematical sciences, peking university, beijing 100871, china 2. Laboratory of Systems and Control and Key State Laboratory of Information Security, Institute of Systems Science, Academy of Mathematics and Systems Science, Chinese Academy of sciences, beijing 100080, china) school of mathematical sciences Peking University Beijing 100871 China. Laboratory of Systems and Control and Key State Laboratory of Information Security Institute of Systems Science Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

The weight hierarchies of a linear [n,k;q] code C satisfying the Near-Chain condition are studied, almost all the weight hierarchies of such code are determined.

关键词： weight hierarchy Near-Chain condition difference sequence linear code.

Two applications of generalized Carleson measures to meromorphic Besov-type spaces

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Chinese Science Bulletin 1998年第15期43卷 1260-1264页

作者： TAN Haiou 1 and XIAO Jie 2 1. Department of Mathematics, Wuyi university, Jiangmen 529020, china 2. school of mathematical sciences, peking university, beijing 100871, china Department of Mathematics Wuyi University Jiangmen China school of mathematical sciences Peking University Beijing China

The generalized Carleson measures are used to characterize the meromorphic Besov_type spaces and to explore some inclusions between these spaces.

关键词： generalized Carleson measures meromorphic Besov_type spaces.

Combinatorial rigidity of unicritical maps

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Science china Mathematics 2010年第3期53卷 831-848页

作者： PENG WenJuan 1, & TAN Lei 2 1 school of mathematical sciences, peking university, beijing 100871, china 2 Departement de Mathematiques, Universited’Angers, Angers 49045, France 1. school of mathematical sciences Peking University Beijing 100871 China2. Departement de Mathématiques Université d’Angers Angers 49045 France

In this paper, we combine the KSS nest constructed by Kozlovski, Shen and van Strien, and the analytic method proposed by Avila, Kahn, Lyubich and Shen to prove the combinatorial rigidity of unicritical maps.

关键词： combinatorial rigidity unicritical maps KSS nest

Pole assignment in descriptor periodic systems

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Science china Mathematics 2005年第10期48卷 1309-1332页

作者： FAN Hung-Yuan~1 LIN Wen-Wei~1 & XU Shufang~2 1. Department of Mathematics,Tsing Hua university,Hsinchu 30043,china 2. LMAM,school of mathematical sciences,peking university,beijing 100871,china 1. Department of Mathematics Tsing Hua University 30043 Hsinchu China 2. LMAM School of Mathematical Sciences Peking University 100871 Beijing China

In this paper a pole assignment problem is considered for the descriptor linear discrete-time periodic systems, which is using the periodic proportional-derivative feedback to modify a given system such that the closed loop system has a specified selfconjugate set of eigenvalues. It is shown that the complete reachability of an open loop periodic system is equivalent to the possibility of assigning an arbitrary set of the eigenvalues to the system by choosing the suitable periodic proportional-derivative feedback.A computational approach is also proposed to solve the problem, which uses the reliable numerical techniques based on the orthogonal transformations. Numerical examples are presented to illustrate the effectiveness of the proposed approach.

关键词： descriptor linear periodic system, pole assignment, proportional and derivative feedback, numerical method, periodic Schur decomposition.

A counter example for nilpotent groups

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Science china Mathematics 2010年第11期53卷 3041-3048页

作者： LIU HeGuo1, ZHANG JiPing2 & LIAO Jun2 1Department of Mathematics, Hubei university, Wuhan 430062, china 2school of mathematical sciences, peking university, beijing 100871, china 1. Department of Mathematics Hubei University Wuhan 430062 China2. School of Mathematical Sciences Peking University Beijing 100871 China

Let R be a ring with 1, I be a nilpotent subring of R (there exists a natural number n, such that In = 0), and I be generated by {xj |j ∈ J} as ring. Write U = 1 + I, and it is a nilpotent group with class ≤ n - 1. Let G be the subgroup of U which is generated by {1 + xj|j ∈ J}. The group constructed in this paper indicates that the nilpotency class of G can be less than that of U.

关键词： nilpotency class nilpotent group nilpotent ring Lie ring

Conformal isoparametric hypersurfaces with two distinct conformal principal curvatures in conformal space

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Science china Mathematics 2010年第4期53卷 953-965页

作者： NIE ChangXiong 1,2,LI TongZhu 3,HE YiJun 4 & WU ChuanXi 5 1 Faculty of Mathematics and Computer sciences,Hubei university,Wuhan 430062,china 2 school of mathematical sciences,peking university,beijing 100871,china 3 Faculty of sciences,beijing Institute of Technology,beijing 100081,china 4 school of mathematical sciences,Shanxi university,Taiyuan 030006,china 5 Institute of Mathematics,Hubei university,Wuhan 430062,china 1. Faculty of Mathematics and Computer sciences Hubei University Wuhan 430062 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. Faculty of Sciences Beijing Institute of Technology Beijing 100081 China4. School of Mathematical Sciences Shanxi University Taiyuan 030006 China5. Institute of Mathematics Hubei University Wuhan 430062 China

The conformal geometry of regular hypersurfaces in the conformal space is *** classify all the conformal isoparametric hypersurfaces with two distinct conformal principal curvatures in the conformal space up to confor... 详细信息

关键词： Lorentz conformal geometry conformal invariants conformal isoparametric hypersurfaces

Perfect reconstruction image modulation based on BEMD and quaternionic analytic signals

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Science china(Information sciences) 2011年第12期54卷 2622-2634页

作者： QIAO LiHong 1 , NIU KaiFu 2 , WANG Ning 2 & PENG LiZhong 2 1 College of Information Science and Engineering, Henan university of Technology, Zhengzhou 450001, china 2 school of mathematical sciences, peking university, beijing 100871, china 1. College of Information Science and Engineering Henan University of Technology Zhengzhou 450001 China2. School of Mathematical Sciences Peking University Beijing 100871 China

Image modulation represents image by meaningful characters such as image instantaneous amplitude and instantaneous frequency. A perfect reconstruction image modulation method is proposed. In detail, the bidimensional empirical mode decomposition (BEMD) is first improved to adaptively decompose image into monocomponents. Then by the quaternionic analytic method, suitable analytic signals is acquired. A new polar form is further proposed to modulate images, then seven characters are derived including instantaneous amplitude and instantaneous frequencies. We demonstrate the techniques on both synthetic and natural images, depict the needle program of the estimated frequencies and obtain the reconstructions that are the same with the original images. The applications in image segmentation and separation establish the validity of characterizing images of this type as sums of locally narrow band modulated components.

关键词： perfect reconstruction image modulation AM-FM representation BEMD quaternionic analytic signals

On notions of harmonicity for non-symmetric Dirichlet form

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Science china Mathematics 2010年第6期53卷 1407-1420页

作者： MA ZhiMing1, ZHU RongChan1, & ZHU XiangChan2 1Institute of Applied Mathematics, Academy of Mathematics and Systems Science, Chinese Academy of sciences, beijing 100190, china 2school of mathematical sciences, peking university, beijing 100871, china 1. Institute of Applied Mathematics Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100190 China2. School of Mathematical Sciences Peking University Beijing 100871 China

In this paper, we extend the equivalence of the analytic and probabilistic notions of harmonicity in the context of Hunt processes associated with non-symmetric Dirichlet forms on locally compact separable metric spaces. Extensions to the processes associated with semi-Dirichlet forms and nearly symmetric right processes on Lusin spaces including infinite dimensional spaces are mentioned at the end of this paper.

关键词： harmonic functions uniformly integrable martingale SPV integrable non-symmetric Dirichlet forms non-symmetric Beurling-Deny decomposition Hunt processes

The effects of shock wave and quasi-traveling wave in the mechanical impact test

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Science china(Technological sciences) 2010年第9期53卷 2535-2541页

作者： WU Mei1,5,SUN ZhongFeng2,ZHANG LuMei3,CHEN Yong1 & JI LinHong4 1 Institute of High Energy Physics,Chinese Academy of sciences,beijing 100049,china 2 school of mathematical sciences,peking university,beijing 100871,china 3 High school of Central university for Nationalities,beijing 100081,china 4 Institute of Mechanical Design,Department of Precision Instruments and Mechanology,Tsinghua university,beijing 100084,china 5 Academy of Opto-electronics,Chinese Academy of sciences,beijing 100190,china 1. Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China5. Academy of Opto-electronics Chinese Academy of Sciences Beijing 100190 China2. School of Mathematical Sciences Peking University Beijing 100871 China3. High School of Central University for Nationalities Beijing 100081 China4. Institute of Mechanical Design Department of Precision Instruments and Mechanology Tsinghua University Beijing 100084 China

It is well-known that the numerical value is always larger than the measured value,amounting to many times,if we calculate the stress of the specimen in the impulse test using the NASTRAN and ANSYS (N-A) *** believe that the impact induces shock wave or quasi-traveling wave in the specimen,which can qualitatively explain the discrepancy of the two *** order to verify it,the Lax-Friedrichs (L-F) scheme is taken to simulate the transmission of shock wave and quasi-traveling wave in *** results show that the action area of the stress wave is small and the action time is very short,so the resulting stress and actual work are not *** addition,the distribution of the impact values obtained by the numerical simulation is in accordance with the trend of the measured impact values.

关键词： aerospace environment test shock wave quasi-traveling wave