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Lipschitz continuity of best approximations and Chebyshev centers

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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,{2., China 2. {3. of Mathematics, hangzhou university, hangzhou 3.002., 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.

Shape blending of artistic brushstroke represented by disk B-spline curves

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Progress in Natural Science:Materials International 2007年第12期17卷 1501-1507页

作者： Cheng Min1,2.and Wang Guojin1(1. department of Mathematics, zhejiang university,{2., China 2. department of Mathematics, zhejiang university of Technology, hangzhou 3.003.0} China) department of Mathematics Zhejiang University Hangzhou 310027 China 2. department of Mathematics Zhejiang University of Technology Hangzhou 310032 China

This paper presents an algorithm for automatically generating in-between frames of two artistic brushstrokes. The basic idea of the algorithm is to represent the two key frames of artistic brushstrokes in disk B-spline curves, and then make blending of their geometric intrinsic variables. Given two key frames of artistic brushstrokes, the skeleton curves can be obtained by certain skeleton-based techniques. After disk B-spline representation of the key frames is generated, interpolation of the intrinsic variables of the initial and the target disk B-spline curves is carried out. Examples show that this method can efficiently create in-between frames of artistic brushstrokes.

关键词： computer aided calligraphy shape blending brushstroke disk B-spline curve skeleton.

Characteristics of fMRI BOLD signal and its neurophysiological mechanism

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Progress in Natural Science:Materials International 2007年第6期17卷 630-638页

作者： Zhao Xiaohu1,2. Wu Yigen3.and Guo Shengli3.1. College of Life sciences, zhejiang university, {2. 3.0058, China 2. Imaging {3. of Tongji Hospital of Tongji university, Shanghai 2.0065, China 3. College of Mathematics and Physics, Nanjing university of Information Science and Technology, Nanjing 2.0044, China) College of Life sciences Zhejiang University Hangzhou 310058 China Imaging department Tongji Hospital Tongji University Shanghai 200065 China College of Mathematics and Physics Nanjing University of Information Science and Technology Nanjing 210044 China

The functional magnetic resonance imaging (fMRI) based on blood oxygen level dependent (BOLD) contrast has emerged as one of the most potent noninvasive tools for mapping brain function and has been widely used to explore physiological, pathological changes and mental activity in the brain. Exploring the nature and property of BOLD signal has recently attracted more attentions. Despite that great progress has been made in investigation of the characteristics and neurophysiological basis, the exact nature of BOLD signal remains unclear. In this paper we discuss the characteristics of BOLD signals, the nonlinear BOLD response to external stimuli and the relation between BOLD signals and neural electrophysiological recordings. Furthermore, we develop our new opinions regarding nonlinear BOLD response and make some perspectives on future study.

关键词： functional magnetic resonance imaging blood oxygen level dependent nonlinear response neural electrophysiological activity.

Low temperature albitization in Caino-Mesozoic reservoir sandstones from North Tarim, and a discussion on the fluid origin

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Chinese Science Bulletin 1999年第S2期44卷 35-37页

作者： YE Ying~1, HU Shouxi~2.and SUN Jinggui~2.1. department of {3. {2.,{3., hangzhou 3.0027, China 2. department of earth sciences, Nanjing university, Nanjing 2.0008, China department of earth {2. Zhejiang University Hangzhou 310027 China department of earth {2. Nanjing University Nanjing 210008 China

CAJNOZOIC and Mesozoic in North Tarim are predominantly a set of terrestrial detrital formations. In thereservoir sandstones in the area, albite is one of the widely developed authigenic mineral. Micro-structural evidence shows that diagenetic albite occurs as euhedral crystals in the pore, and replaces feldsparand other detritus along cleavage and micro-crack. EPMA analyzing found that some of the alteration product has a chemical composition between purealbite and the replaced detrital feldspar. For example, composition of replaced alkali feldspar is betweenmicrocline and albite, and content of altered plagioclase decreases continuously. This has been regardedas direct evidence for fluid replacement, for feldspar crystallized from solution or magma is usually withfixed chemical composition. Taking alkali feldspar as an example, although Kf and Ab forming completeisomorphous admixture in high temperature, they exsolved out as two relative pure phases while temperature decreases.

关键词： low temperature albitization sandstones fluid origin North Tarim.

Experimental remolding on the caprock's 3. strain field of the Indosinian-Yanshanian epoch in Tongling deposit concentrating area

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Science China earth sciences 2005年第7期48卷 863-874页

作者： DENG Jun1,HUANG Dinghua2.WANG Qingfei1,WAN Li1,SUN Zhongshi3.YANG Liqiang1 & GAO Bangfei1 1. State Key Laboratory of Geological Processes and Mineral Resources,China university of Geosciences,Beijing 100083.China 2. Faculty of {2. sciences,China university of Geosciences,Wuhan 43.074,China 3. department of {2. sciences,Jilin university,Changchun 13.061,China State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences Beijing 100083 China Faculty of earth sciences China University of Geosciences Wuhan 430074 China department of earth {2. Jilin University Changchun 130061 China

Based on field observations and rheology analysis, we perform one analogue experiment and remold the 3. structural frame of Tongling deposit concentrating area firstly. Then we disassemble and dialyze the 3. structures of the model using the methods of "slicing" and "stripping". A series of sliced planes vertical to the fold hinges show similar landscapes of that in the drill hole profiles. Meanwhile, layer stripping analysis indicates that the deformation features of each layer in the model are qualitatively analogical to those obtained from field observations. Through contrasting the 3. structure between the experimental model and the field phenomena, we verify the following 3. deformation features of the caprock in this area: (1) the Tongling area mainly consists of three series of NE S-typed fold groups; (2. in the uniform stress field, the incoherent folds universally develop in different positions, along different axes as well as in different strata; (3. the faults propagate upward which are mostly inter-bedded detachment faults, while the fold amplitudes decrease while going deeper; and (4) the folds and cleavages are highly developed in the Silurian System indicating that the deformation effect of the Indosin-ian-Yanshanian structural layer terminates at this layer, which suggests that the Silurian System is the crucial layer for the inversion between brittle and plastic deformation domains and the underlying strata are subject to the control of another deformation system with distinct properties.

关键词： Tongling deposit concentrating area Indosinian-Yanshanian epoch 3. structural frame of the caprock analogue experiment slicing and stripping analysis structural model.

The Lanshantou Kyanite-bearing Eclogite with Coesite Inclusions in the Sulu Ultrahigh-Pressure Metamorphic Belt and Its PTt Path

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Acta Geologica Sinica(English Edition) 2001年第4期75卷 409-420页

作者： HU Shouxi, SUN Jinggui, LING Hongfei, YE Ying, Fang Changquan and ZHAO Yiying department of earth {2., Nanjing {3., Nanjing 2.0008, Jiangsu department of earth {2., zhejiang university, hangzhou 3.0027, zhejiang department of earth {2. Zhejiang University Hangzhou 310027 Zhejiang [?]3.u Shouxi Born in 192. graduated from zhejiang university in 1952 now professor of geoscience at Nanjing university. His main research interests are mineral deposits and petrology. E-mail: hushouxi@***.

Coesite inclusions are found in kyanite from the Lanshantou eclogite in the Sulu ultrahigh-pressure (UHP) metamorphic belt. This discovery extends the stable region of kyanite to over 2.4 GPa. As an important UHP metamorphic belt in China, the Sulu eclogite belt is the product of A-subduction induced by strong compression of the Yellow Sea terrane to the Jiaodong-northereastern Jiangsu terrane during the interaction of the Eurasian plate and Palaeo-Pacific plate in the Indosinian. It stretches about 3.0 km and contains over 1000 eclogite bodies. Most eclogites in this belt belong to Groups B and C in the classification of Coleman et al., and commonly contain kyanite, while the Lanshantou eclogite belongs to Group A and contains coesite. The MgO, CaO and FeO contents in garnet and pyroxene show regular variation from the core to the rim, which reveals the PTt paths of progressive metamorphism during the Early Mesozoic (2.0-2.0 Ma) and retrogressive metamorphism during the Late Mesozoic and Cenozoic exhumation.

关键词： coesite-bearing kyanite eclogite ultrahigh-pressure (UHP) metamorphic belt PTt path of subduction and exhumation

The role of aerial algae in the formation of the landscape of the Yunnan Stone Forest,Yunnan Province, China

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Science China earth sciences 2004年第9期47卷 846-864页

作者： TIAN Youping1,3. ZHANG Jie2. SONG Linhua1 & BAO Haosheng2.1. Institute of Geographic sciences and Natural Resources Research, Chinese Academy of sciences, Beijing 100101, China 2. {2. of Geography, Nanjing {3., Nanjing 2.0093. China 3. School of earth sciences and Resources, China {3. of Geosciences, Beijing 100083. China Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China department of Geography Nanjing University Nanjing 210093 China School of earth sciences and Resources China University of Geosciences Beijing 100083 China

Aerial algae on the surface of carbonate rocks at the Stone Forest, Shilin County, Yunnan Province, China, and their bioerosion were investigated in the field and studied in the laboratory in detail. Through the observation, identification and statistics of more than one hun- dred algal samples and rock samples with the optical microscopes (stereomicroscope, biological microscope) and the scanning electronic microscope (SEM), the relationships between erosional forms on the surface of the Stone Forest and algae and/or algal communities and the genetic mechanism for the formation of erosional forms were analyzed. It is suggested that aerial algae play an active role in bioerosive processes that may affect the formation of karst erosional forms. These effects include both direct and indirect ones. The direct effect is the initiative control (algal shape-controlling role) of algae on the formation of karst forms of various scales, mostly mi- cro-scale (3.) and minor-scale (10-3.10-1m) erosional forms. The algal shape-controlling roles can be divided into the algal individual shape-controlling role and the algal community shape-controlling role. The former mostly controls the formation of micro-scale erosional forms, while the latter mostly controls the formation of micro-scale and smaller minor-scale erosional forms. The indirect effect refers to the promoting role of algae in the formation of karst forms, which may affect the formation of karst forms of all types and scales. The bioerosion of algae accelerates the weathering process of the whole Stone Forest karst landforms.

关键词： aerial algae, bioerosion, the Stone Forest, Yunnan Province, China.

Structural phase transition in nanostructured γ-Fe_2._3

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Chinese Science Bulletin 1997年第11期42卷 894-897页

作者： YE Xisheng, SHA Jian, SONG Hongqin, JIAO Zhengkuan, LU Guanglie, PENG Zifei and ZHANG Lide1. department of Physics, zhejiang university,{2., China 2. Central Laboratory, {3. university, {3. 3.002., China 3. Institute of Solid State Physics, Chinese Academy of sciences, Hefei 2.003., China department of Physics Zhejiang IJniversity Hangzhou China Central laboratory Hangzhou University Harigzhou China Institute of Solid State Physics Chinese Academy of Sciences Hefei China

DUE to their specific physical,chemical and mechanical properties and large application proba-bility in many fields,nanostructured materials have been developing very fast in the recent *** stability is an important property of the *** interesting resultshave been obtained in the study of the thermal stability of nanostructured materials.

关键词： nanostructured γ-Fe2.3 differential thermal analysis (DTA) XRD microstructlire structural phase transition.

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

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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