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Smoothness for the collision local times of bifractional Brownian motions

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science China Mathematics 2011年第9期54卷 1859-1873页

作者： SHEN GuangJun 1,2,& YAN LiTan 3.1 Department of Mathematics,east China university of science and {3.,shanghai 20023.,China 2 Department of Mathematics,Anhui Normal university,Wuhu 241000,China 3.Department of Mathematics,Donghua university,shanghai 201620,China 1. Department of Mathematics East China University of Science and Technology Shanghai 200237 China2. Department of Mathematics Anhui Normal University Wuhu 241000 China3. Department of Mathematics Donghua University Shanghai 201620 China

Let B^Hi,Ki ={ Bt^Hi,Ki, t ≥ 0}, i= 1, 2 be two independent bifractional Brownian motions with respective indices Hi ∈ （0, 1） and K∈ E （0, 1]. One of the main motivations of this paper is to investigate f0^Tδ（Bs^H1 ,K1 - the smoothness of the collision local time, introduced by Jiang and Wang in 2009, IT = f0^T δ（Bs^H1,K1）ds, T 〉 0, where 6 denotes the Dirac delta function. By an elementary method, we show that iT is smooth in the sense of the Meyer-Watanabe if and only if min{H-1K1, H2K2} 〈-1/3.

关键词： bifractional Brownian motion collision local time intersection local time chaos expansion

Fractal Structure of the Core Loss Spectrum of Co-based Amorphous Soft Magnetic Alloy with Constant Permeability

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International Journal of Minerals,Metallurgy and Materials 1999年第1期13卷 54-56页

作者： Yiping Chen (Applied science school, university of science and technology Beijing, Beijing 100083. China) Applied science school University of Science and Technology Beijing Beijing 100083 China

In order to check the traditional core loss formula, the core loss spectrum P(f) of Co-based amorphous soft magnetic alloy with constant permeability has been studied. It is found that within a high frequency range from 10 kHz to 200 kHz and at Bm = 0. 1 T,the P(f) has the fractal structure P (f) = Po, and with the increasing of induced anisotropy energy Ku, the fractal dimension Dfrises, thus the total power loss at high frequency increases and the frequency characteristic of P(f) becomes worse.

关键词： amorphous soft magnetic alloy constant permeability core loss fractal

Ferroelectric properties of Bi_(3.4)Ho_(0.6)Ti_3._(12) thin films prepared by sol-gel method

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science China(Technological sciences) 2008年第9期51卷 1439-1444页

作者： FU ChengJu1, HUANG ZhiXiong1, LI Jie2 & GUO DongYun3.1 school of Materials science and technology, Wuhan {3. of technology, Wuhan 43.070, China 2.school of Mechanical Engineering, Chongqing {3. of science and technology, Chongqing 400050, China 3.Department of Physics, Wuhan {3., Wuhan 43.072, China school of Materials science and technology Wuhan University of Technology Wuhan 430070 China school of Mechanical Engineering Chongqing University of Science and Technology Chongqing 400050 China Department of Physics Wuhan University Wuhan 430072 China

We have prepared the Ho-substituted bismuth titanate (Bi3.4Ho0.6Ti3.12, BHT) thin films on Pt/Ti/SiO2/Si substrates using sol-gel method. The crystal structure and morphology of the films were characterized using X-ray diffraction and atomic force microscopy. The BHT film shows a single phase of Bi-layered Aurivillius structure and dense microstructure. The 2Pr and 2Ec of the 600-nm-thick BHT film were 3..4 μC/cm2 and 3.6.1 kV/cm, respectively at applied electric field 500 kV/cm. The dielectric constant and dielectric loss are about 3.0 and 0.015 at a frequency of 1 MHz, respectively. The Pr value decreased to 93. of its pre-fatigue values after 4.46×109 switching cycles at 1 MHz frenquency, and the BHT film shows good in-sulating behavior according to the test of leakage current.

关键词： Bi3.4Ho0.6Ti3.12 thin film sol-gel method ferroelectric property fatigue dielectric constant

An adaptive version of ghost-cell immersed boundary method for incompressible flows with complex stationary and moving boundaries

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science China(Physics,Mechanics & Astronomy) 2010年第5期53卷 923-932页

作者： WANG Liang1 & WU ChuiJie2,3.1 school of science,PLA university of science and technology,Nanjing 211101,China 2 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian university of technology,Dalian 116024,China 3.school of Aeronautics and Astronautics,Dalian university of technology,Dalian 116024,China 1. school of science PLA University of Science and Technology Nanjing 211101 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. School of Aeronautics and Astronautics Dalian University of Technology Dalian 116024 China

An adaptive version of immersed boundary method for simulating flows with complex stationary and moving boundaries is *** method employs a ghost-cell methodology which allows for a sharp representation of the immersed *** simplify the implementation of the methodology,a volume-of-fluid method is introduced to identify the immersed *** addition,the domain is spatially discretized using a tree-based discretization which is relatively simple to implement a fully flexible adaptive refinement ***,the methodology is validated by comparing it with numerical and experimental results on three cases:(1) the flow passing a circular cylinder at Re=40 and Re=100,(2) a periodic oscillation of a circular cylinder in fluid at rest and(3. the self-propelled fish-like swimming at Re=6400.

关键词： adaptive mesh refinement ghost-cell immersed boundary method moving boundaries

Analysis for twinning and slip in face-centered cubic crystals under axisymmetric co-deformation

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science China(Technological sciences) 2006年第5期49卷 521-536页

作者： CHEN Zhiyong1,2, CAI Hongnian1, ZHANG Xinming2, WANG Fuchi1 & TAN Chengwen1,3.1. school of Material science and Engineering, Beijing Institute of technology, Beijing 100081, China 2. school of Material science and Engineering, Central South university, Changsha 410083. China 3. school of Material science and Engineering, Beijing university of Aeronautics and Astronautics, Beijing 100083. China 1. school of Material science and Engineering Beijing Institute of Technology Beijing 100081 China 2. school of Material science and Engineering Central South University Changsha 410083 China 3. school of Material science and Engineering Beijing University of Aeronautics and Astronautics Beijing 100083 China

The maximum work principle of Bishop-Hill was developed to analyze the axisymmetric co-deformation in face-centered cubic crystals (f.c.c.) for twinning on {111} 112 and slip on {111} 110 systems. The influence of ξ , the ratio of critical re- solved shear stress for twinning to slip, on the yield stress states and corresponding active slip or/and twinning systems for orientations in the standard stereographic triangle of cubic crystal was investigated systematically. The Taylor factors and the anisotropy of yield strength for three important orientations [100], [110] and [111] in orientation space were analyzed. It is found that the yield strength asymmetry for the case of axisymmetric de- formation of tension and compression can be explained based on the microscopic theory of crystal plasticity. The concept of orientation factor for twinning ability was proposed and the deformation mechanism map in the orientation space was established for the case of axisymmetric deformation. The deformation texture formation and development of f.c.c. crystals with low stacking fault energy for axisymmetric tension can be explained qualita- tively on the basis of analyzed results.

关键词： twinning slip face-centered cubic crystals axisymmetric co-deformation Bishop-Hill maximum work principle yield strength anisotropy

Nonsmooth Equations of K-T Systems for a Constrained Minimax Problem

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Journal of Systems Engineering and Electronics 2003年第2期14卷 31-35页

作者： Gao Yan school of Management, university of shanghai for {3. and technology, shanghai 200093. P. R. China school of Management University of Shanghai for Science and Technology Shanghai 200093 P. R. China

Using K-T optimality condition of nonsmooth optimization, we establish two equivalent systems of the nonsmooth equations for the constrained minimax problem directly. Then generalized Newton methods are applied to solve these systems of the nonsmooth equations. Thus a new approach to solving the constrained minimax problem is developed.

关键词： Optimization Minimax problems Nonsmooth equations Generalized Newton methods.

Algorithm for Computation of Unstructured Real Stability Radius and Its Applications

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 245-250页

作者： Xiaodan Zhang Lequan Min(Applied science school, university of science and technology Beijing, Beijing 100083. China) Applied science school University of Science and Technology Beijing Beijing 100083 China

An algorithm for the computation of the unstructured real stability radius of high dimensional linearsystem is presented. Using the accurate formula of the real stability radius of 2-dimensional system linear systemchecks the algorithm. The result shows that the algorithm is reliable and efficient. As applications, the unstructuredreal stability radii of 2-dimensional Chua's circuit and 3.dimensional piecewise-linear system are calculated, thedynamical orbits of the corresponding perturbed systems are simulated.

关键词： lincar systems stability robustness parameter perturbation computational methods

Spatial continuity incorporated multi-attribute fuzzy clustering algorithm for blood vessels segmentation

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science China(Information sciences) 2010年第4期53卷 752-759页

作者： HAO JuTao1*, ZHAO JingJing2 & LI MingLu3.1school of Optical-Electrical and Computer Engineering, university of shanghai for {3. and technology, shanghai 200093. China 2Department of Electrical Engineering, shanghai university of Electric Power, shanghai 200090, China 3.epartment of Computer {3. and Engineering, shanghai Jiaotong university, shanghai 2.02.0, China 1. school of Optical-Electrical and Computer Engineering University of Shanghai for Science and Technology Shanghai 200093 China2. Department of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 China3. Department of Computer Science and Engineering Shanghai Jiaotong University Shanghai 200240 China

A three-dimensional representation of vasculature can be extremely important in image-guided neurosurgery, pre-surgical planning. In this paper, a spatial continuity incorporated multi-attribute fuzzy clustering algorithm (MAFCM S) is proposed to segment entire blood vessels from TOF MRA images. This clustering method takes both the intensity information and the geometrical information into account, while most of the cur- rent clustering methods only deal with the former. In this method, a new dissimilarity measure, which integrates the intensity and the geometry shape dissimilarity, is introduced. Because of the presence of the geometrical information, the new measure is able to differentiate the pixels with similar intensity values within different geometrical shape structures. Experimental results show that the new algorithm can get better segmentation.

关键词： fuzzy c-means clustering scale space analysis spatial continuity blood vessel segmentation multi-attribute fuzzy clustering

Nonclassical Plane-crystallographic Groups and Their Applications IV

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International Journal of Minerals,Metallurgy and Materials 1998年第4期12卷 228-232页

作者： Lequan Min Xaodan zhang(Applied science school, school,{3. of science and technology Beijing, Beijing 100083.China) Applied science school University of Science and Technology Beijing Beijing 100083 China

Eight kinds of nonclasslcal periodic lattices with locally 8-fold rotational symmetries are *** can be described via nonclassical Planc-crystallographic groups. The periodic lattices may be interpreted bythe projections on the plane of the corresponding unit cells consisting of embedding polyhedrons, respectively. TheFourier-transform patterns of the Periodic lattices have striking approximate'8-fold rotational symmetries', some ofwhich are similar to those displaying in the electrton-diffraction patterns of so-called quasicrystals.

关键词： nonclasslcal crystallographic groups locoally 8-fold symmetry Fourier-transform patterns, quasicrystals