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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, Hangzhou 310058, china 2. Imaging {2. 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.

Model test of the tunnel subjected to high water pressure in Jinping Second Cascade Hydropower Station,china

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Science china(Technological Sciences) 2011年第S1期54卷 192-198页

作者： WANG JianXiu 1,2.FENG Bo 2.HU LiSheng 2.TIAN PuZhuo 2.SUI DongChang 2.TANG YiQun 1,2.&YANG Ping 1,2.1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,{2. 2.0092.china 2.department of Geotechnical Engineering,tongji university,{2. 2.0092.china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

In the area with high groundwater pressure,grout curtain is often adopted to reduce the water pressure on tunnel lining.A series of model tests for the diversion tunnel of the Jinping Second Cascade Hydropower Station,china,is designed to study the effect of grout *** impact of the thickness of grout curtain,permeability of grout curtain,internal water pressure and drainage inflow on the distribution of water pressure are *** results indicates that under un-drained condition,water pressure is equal to hydrostatic one no matter grout curtain is selected or not,water pressure under drained condition is far less than that of un-drained condition,drainage in tunnel can reduce tunnel water pressure *** same inflow,both increasing of thickness and decrease of hydraulic conductivity of grout curtain can reduce water pressure *** the same water pressure,the smaller inflow of grout curtain,the less volume of water to be *** impact of hydraulic conductivity of grout curtain is more obvious than that of *** increasing of internal water pressure,the water pressure of grout curtain increases too,and the water pressure increases nearly *** proposed thickness of grout curtain for the diversion tunnels is 16 m.

关键词： tunnel grout curtain water pressure model test

Macro-micromechanical approaches for non-coaxiality of coarse grained soils

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中国科学：技术科学英文版 2011年第S1期54卷 147-153页

作者： QIAN JianGu 1,2.HUANG MaoSong 1,2.& SUN HaiZhong 1,2.1 Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education,tongji university,{2. 2.0092.china 2.department of Geotechnical Engineering,tongji university,{2. 2.0092.china 1. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji University Shanghai 200092 China2. Department of Geotechnical Engineering Tongji University Shanghai 200092 China

For coarse grained soils,their principal stress directions may change when the water level of embankment dam varies *** this loading case,the principal directions of stress and strain rate will become *** an effort to model non-coaxial behavior,a modified three-dimensional non-coaxial model is developed in the context of vertex yield(tangent plasticity) *** Element Method(PFC) incorporating user-defined interparticle contact models is also employed to gain an insight into microscopic mechanism of *** analysis focuses on non-coaxial behaviors under simple shear *** has been shown that the proposed non-coaxial model gives good predictions for non-coaxiality with reference to microscopic observations while the classical coaxial model fails to simulate the non-coaxial *** general,non-coaxiality as a result of the rotation of principal stress,is large at a small shear strain,and inclined to become negligible with increasing shear *** coarse grained soils,their non-coaxiality tends to largely depend on the initial normal pressure,where a larger degree of non-coaxiality can be observed at a higher pressure.

关键词： coarse grained soils non-coaxiality particle flow code simple shear

Simultaneously inducing synthesis of semiconductor selenium multi-armed nanorods and nanobars through bio-membrane bi-templates

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Science china Chemistry 2004年第6期47卷 507-511页

作者： LI Li1, WU Qingsheng1 DING Yaping2.& LI Ping3 1. department of Chemistry, tongji {2., shanghai 2.0092. china 2. department of Chemistry, shanghai {2., shanghai 2.0436, china 3. department of Food, Anhui Agricultural {2., Hefei 2.0036, china 1. department of Chemistry Tongji University 200092 Shanghai China 2. department of Chemistry Shanghai University 200436 Shanghai China 3. department of Food Anhui Agricultural University 230036 Hefei China

Multi-armed nanorods and nanobars of semiconductor selenium were simultane- ously synthesized in the light of biomineralization process through bio-membrane bi-templates of rush at room temperature. The multi-armed nanorods are 60 nm in diameter and 1.5 μm in length; the nanobars are 150 nm in diameter and 1000—1100 nm in length. The XRD pattern indicates that these nanocrystals were crystallized in the hexagonal structure with lattice constants a = 0.437 nm, c = 0.495 nm. The possible formation mechanism was investigated.

关键词： selenium, multi-armed nanorods, nanobars, bio-membrane, bi-templates.

Two-dimensional thermoelasticity solution for functionally graded thick beams

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Science china(Physics,Mechanics & Astronomy) 2006年第4期49卷 451-460页

作者： Lü Chaofeng1, CHEN Weiqiu1 & ZHONG Zheng2.1. department of Civil Engineering, Zhejiang university, Hangzhou 31002.,{2. 2. Key Laboratory of Solid Mechanics of Ministry of Education, School of Aerospace Engineering and Ap- plied Mechanics, tongji university, shanghai 2.0092.{2. department of Civil Engineering Zhejiang University Hangzhou 310027 China Key Laboratory of Solid Mechanics of Ministry of Education School of Aerospace Engineering Applied Mechanics Tongji University Shanghai 200092 China

Two-dimensional thermoelasticity analysis of functionally graded thick beams is presented using the state space method coupled with the technique of differential quadrature. Material properties vary continuously and smoothly through the beam thickness, leading to variable coefficients in the state equation derived from the elasticity equations. Approximate laminate model is employed to translate the state equation into the one with constant coefficients in each layer. To avoid numerical instability, joint coupling matrices are introduced according to the continuity conditions at interfaces in the approximate model. The differential quadrature procedure is applied to discretizing the beam in the axial direction to make easy the treatment of arbitrary end conditions. A simply-supported beam with exponentially varying material properties is considered to validate the present method. Numerical examples are performed to investigate the influences of relative parameters.

关键词： state equation differential quadrature approximate laminate model joint coupling matrices thermal stresses.

Multiresolution Terrian Model in GIS

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测绘学报 2002年第Z1期31卷 92-98页

作者： ZHANG Jin 1,TONG Xiao hua 2.(1. department of Surveying and Mapping, Taiyuan university of Technology, Taiyuan 03002.,{2. 2. department of Surveying and Geo informatics, tongji university, shanghai 2.0092.{2.) department of Surveying and Mapping Taiyuan University of Technology Taiyuan 030024 department of Surveying and Geo-informatics Tongji University 上海 200092

DEM, which becomes a major component of geographic information processing in earth and engineering sciences, has been studied in the GIS literature for a long time. We use DEM to represent the terrain in GIS. The more data are available, the better representations of a terrain can be built. But not all tasks in the framework of a given application necessarily require the same accuracy, and even a single task may need different levels of accuracy in different areas of the domain. Multiresolution models, such as LOD, offer the possibility of representing and analyzing a terrain at a range of different levels of detail. In this paper, some key issues in multiresolution DEM model are studied. Three main models are focused on Hierarchical TIN(HTIN), multiresolution terrain model based Delaunay and Hierarchical Dynamic Simplification. The advantages and disadvantages of these methods are analyzed. The technology of tile to tile edge match is studied to maintain the consistency between adjacent edges and tile edges in HTIN model. And the Hypergraph based Objected oriented Model(HOOM) is presented to divide and code spatial area and describe the terrain feature in adding and deleting points based on Delaunay rule retriangulating. The conclusions have been drawn in the end.

关键词： DEM multiresolution LOD GIS

THE INDUCED REPRESENTATION OF C^＊-GROUPOID DYNAMIC SYSTEMS

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Chinese Annals of Mathematics,Series B 1996年第1期17卷 103-114页

作者： FANG XIAOCHUN(department of Mathematics, tongji {2., shanghai 2.002., china.) tongji UNIV DEPT MATHSHANGHAI 200029PEOPLES R CHINA

Let G be a second countable locally compact groupoid with Haar system {λu}, H be a closed subgroupoid containing Go with Haar system {λuH}. *** introduced the C*-Groupoid dynamic system (G, A, α) and its reduced crossed product Cr.d(G, A) in [2., where A is a C*-algebra, α is the homomorphism G→Aut(A). In this paper the author introduces the C*-groupoid dynamic systems (H, A, α|H) and (H\G2. A, α) induced by (G, A, α) and proves that C~*red(H, A) and C~*red(H\G2. A) are strongly Morita equivalent. Moreover the induced representation from C~*red(H, A) to C~*red(G, A) is got.

关键词： C~*-groupoid dynamic system Induced representation Haar system

Schwarz-Pick estimates for positive real part holomorphic functions on unit ball and polydisc

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Science china Mathematics 2010年第4期53卷 1017-1024页

作者： LIU Yang 1,& CHEN ZhiHua 2.1 department of Mathematics,Zhejiang Normal university,Jinhua 32.004,{2. 2.department of Mathematics,tongji university,shanghai 2.0092.{2. 1. department of Mathematics Zhejiang Normal University Jinhua 321004 China2. Department of Mathematics Tongji University Shanghai 200092 China

We give higher order derivatives Schwarz-Pick estimates for all positive real part holomorphic functions on Bn and D n,and generalize early work on Schwarz-Pick estimate of higher order derivatives for holomorphic fun... 详细信息

关键词： Schwarz-Pick estimate holomorphic function Taylor expansion

p-th moment exponential stability of stochastic differential equations with impulse effect

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Science china(Information Sciences) 2011年第8期54卷 1702-1711页

作者： SHEN LiJuan 1,2.& SUN JiTao 11 department of Mathematics, tongji {2.,shanghai 2.0092.china 2.department of Mathematics,Luoyang Normal {2., Luoyang 47102.,china 1. department of Mathematics Tongji University Shanghai 200092 China2. Department of Mathematics Luoyang Normal University Luoyang 471022 China

The p-th moment exponential stability of stochastic differential equations with impulse effect is *** employing the method of vector Lyapunov functions,some sufficient conditions for the p-th moment exponential stability are *** addition,the usual restriction of the growth rate of Lyapunov function is replaced by the condition of the drift and diffusion coefficients to study the p-th moment exponential *** examples are also discussed to illustrate the effectiremess of the results obtained.

关键词： stochastic differential equations impulse p-th moment exponential stability vector Lyapunov functions