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Geochemical characteristics and tectonic implications of HP-UHP eclogites and blueschists in southwestern Tianshan, china

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Progress in Natural Science:Materials International 2006年第6期16卷 624-632页

作者： AI Yongliang, ZHANG Lifei, LI Xuping and QU Junfeng (MOE Key Laboratory of Orogenic Belt and Crust Evolution, school of Earth and Space Sciences, peking university, beijing 100871, china school of Geosciences and Resources, china university of Geosciences, beijing 100083, china) MOE Key Laboratory of Orogenic Belt and Crust Evolution School of Earth and Space Sciences Peking University Beijing 100871 China school of Geosciences and Resources China University of Geosciences Beijing 100083 China

Four rock assemblages in correspondence with two different tectonic settings have been recognized in the NEE-SWW extending HP-UHP metamorphic belt in southwestern Tianshan, northwest china. Eclogite assemblage EC1 is geochemically akin to alkaline within-plate oceanic island basalt (OIB). EC2 shows affinity to enriched mid-oceanic ridge basalt (EMORB). Rare earth element (REE) and other immobile trace element characteristics of blueschist assemblage BS1 resemble those of normal mid-oceanic ridge basalt (NMORB). These three assemblages are likely formed on a seamount setting, and the prevalent presence of carbonate minerals and om-phacite quartzite stripes/gobbets suggests ancient pelagic sediments including marls are probably developed upon the basaltic seamount. Whereas the geochemical characteristics of BS2 assemblage are of volcanic arc basalt-type. The seamount with the pelagic sediments on it is brought into the subduction zone, and volcanic arc basalts formed on the active continental margin and trench sediments are eroded and enwrapped in the subducting mass, they are altogether subjected to high to ultrahigh pressure metamorphism and subsequent exhumation towards surface. The HP-UHP metamorphic belt is thus interpreted as a subduct ion-accretionary complex formed by tectonic juxtaposition and imbrication of seamount, seafloor, trench and volcanic arc sequences during oceanic crust subduction.

关键词： southwestern Tianshan HP-UHP metamorphic belt snbduction-accretion complex trace element geochemistry.

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NUMERICAL APPLICATION OF THE RECURSION METHOD TO THE ELECTRONIC STRUCTURE OF C60

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原子与分子物理学报 1997年第3期 25-29页

作者： Lu Jing Zhang LiyuanDepartment of physics, peking university, beijing 100871, P.R.china

采用Ｒｅｃｕｒｓｉｏｎ方法计算了Ｃ６０分子的能态密度，所得的能隙、能级的简并度及顺序与ＬＤＡ方法或者解析方法得到的结果吻合。

关键词： C60 电子结构

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Recent HERMES Results on DVCS from Proton and Nuclear Targets

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原子核物理评论 2009年第S1期26卷 124-128页

作者： YE Hong-xue,MAO Ya-jun (school of physics and State Key Laboratory of Nuclear physics and Technology,peking university,beijing 100871,china) school of physics and State Key Laboratory of Nuclear physics and Technology Peking UniversityBeijing 100871China

Spin structure is one of the fundamental subjects in the study of nucleon structure. Recently it is found that Generalized Parton Distributions(GPDs) are related to the total angular momentum carried by partons,which offers a possible solution to the spin puzzle in the first time. We get access to certain GPDs by looking at the azimuthal angle asymmetries attributed to the interference between Deeply Virtual Compton Scattering(DVCS) and Bethe-Heilter processes in HERMES experiment. By measuring the asymmetry with respect to transverse target polarization from proton target,a model-dependent constraint on Ju vs Jd is obtained. Another worldwide unique channel is nuclear DVCS. The preliminary results on asymmetries with respect to beam spin and beam charge are reported.

关键词： GPDs DVCS TTSA nuclear DVCS

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Effects of diffusion time and diffusion gradient strength on the mean diffusivity of water molecules in healthy human brain

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Progress in Natural Science:Materials International 2006年第7期16卷 706-711页

作者： GAO Song, WANG Xiaoying and BAO Shanglian ( Laboratory of Medical physics & Engineering, peking university, beijing 100871, china Department of Radiology, The First Affiliated Hospital of peking university, beijing 100034, china) peking Univ Lab Med Phys & Engn Beijing 100871 Peoples R China peking Univ Affiliated Hosp 1 Dept Radiol Beijing 100034 Peoples R China

Diffusion time and diffusion gradient strength are two important parameters of pulsed gradient spin echo (PGSE) that is the most commonly used method in diffusion-weighted magnetic resonance imaging. However, the effects of the diffusion time on the mean diffusivity (MD) in previous studies are controversial. In this study, a new experimental protocol was designed to evaluate the effects of the two parameters on the results of PGSE. It was found that MD decreased significantly with the increased diffusion time or increased diffusion gradient strength, which cannot be explained by the previous theories. Through theoretical analysis, we found the flaw in the pulsed gradient spin echo (PGSE) method, which is the explanation for the controversial results of diffusion time obtained by oth- ers.

关键词： diffusion time diffusion gradient strength diffusion-weighted imaging diffusion tensor imaging mean diffusivity.

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Categories and characteristics of urban villages by GIS-based analysis:A case study of the Shenzhen Special Economic Zone

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Science china(Technological Sciences) 2010年第S1期53卷 150-157页

作者： TONG De1,FENG ChangChun2,LI GuiCai1 & CHEN Peng1,2 1S henzhen Graduate school,peking university,Shenzhen 518055,china 2College of Urban and Environmental Science,peking university,beijing 100871,china Shenzhen Graduate school Peking University Shenzhen China College of Urban and Environmental Science Peking University Beijing China

Studies on the characteristics of urban villages have attracted much interest in urban ***,how to advance the development of further theoretical analysis and quantitative methodologies,especially in the era that GIS and digital-urban technologies develop rapidly and provide precious resources on spatial issues,has always been a heated debate and *** this paper,a mathematical model based on spatial analysis is introduced to deal with the categorization and characterization of urban villages.A total of 89 urban villages in the Shenzhen Special Economic Zone(SEZ)are used in this case *** ArcGIS tools on buffer analysis,distance and density calculation,and socio-economic and spatial attributes conjunction,urban villages’31 spatial variables in 4 aspects—social,economic,locational,and physical—are extracted,and 6 principal factors are concluded by principal components analysis to indicate the spatial characteristic of urban *** on the 6 principal factors,6 types of urban villages,including rapidly sprawling,large,rapidly industrializing periphery,overcrowded,intensively mobile and economically backward,are divided through the Hierarchical Clustering ***,the spatial features and formation mechanisms of each type of urban villages are ***,the advantages and the shortcomings of the methodology for this specific application are also ***,several guidelines on urban village management and renewal are provided based on the result of type *** outcome of the paper depends on the informational and technological support from the development of digital-city management,and is able to in turn provide basis on monitoring and improving urban villages which can further digital urban framework.

关键词： urban villages GIS-based analysis principal component hierarchical cluster the Shenzhen Special Economic Zone (SEZ)

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Paleoceanographic evolution recorded in the northern South china Sea since 4 Ma

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Science china Earth Sciences 2005年第12期48卷 2166-2173页

作者： HUANG Baoqi1,2, JIAN Zhimin2 & WANG Pinxian2 1. school of Earth and Space Sciences, peking university, beijing 100871, china 2. Laboratory of Marine Geology, Tongji university, Shanghai 200092, china school of Earth and Space Sciences Peking University Beijing China Laboratory of Marine Geology Tongji University Shanghai China

Upper water structure over the last 4 million years in the northern South china Sea (SCS) was reconstructed by sea surface temperature (SST) and primary productivity estimated by changes in the abundance of planktonic foraminifer, planktonic foraminifer transfer function, and the accumulation rate of benthic foraminifera. Results of SST and primary productivity show that SST gradually decreased since 4 Ma, but differential seasonal temperature and primary productivity increased in steps mainly at about 3.1, 2.7, 2.1, 1.6, 0.9 and 0.5 Ma. Comparison with tectonics and orbital variations indicates that phased rising of the Tibet since 3.6 Ma, closing of Panama and Indonesian seaways, and orbital changes were responsible for the changes of upper water structure in the SCS, respectively.

关键词： northern South china Sea, upper water structure, Late Pliocene, planktonic foraminifer, ODP 1146.

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Two Parameter Smooth Martingales on the Wiener Space

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Acta Mathematica Sinica,English Series 1997年第2期13卷 239-246页

作者： Liang Zongxia (school of Mathematical Science,peking university,beijing 100871,china) school of Mathematical Science Peking University 100871 Beijing China

We prove that two parameter smooth continuous martingales have ∞-modification and establish a Doob’s inequality in terms of(p,r)-capacity for two parameter smooth martingales.

关键词： Two parameter smooth martingales ∞-modifications Doob’s inequality (p,r)-capacity

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Convergence for Imaginary Time Step evolution in the Fermi and Dirac seas

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Science china(physics,Mechanics & Astronomy) 2010年第2期53卷 327-330页

作者： LI FangQiong1,ZHANG Ying2 & MENG Jie2,3,4 1Guizhou university for Nationalities,Guiyang 550025,china 2State Key Lab Nucl. Phys. & Tech.,school of physics,peking university,beijing 100871,china 3school of physics and Nuclear Energy Engineering,Beihang university,beijing 100191,china 4Department of physics,university of Stellenbosch,Stellenbosch,South Africa Guizhou university for Nationalities Guiyang China (GRID:grid.443382.a) (ISNI:***) peking university State Key Lab Nucl. Phys. &amp Tech. School of Physics Beijing China (GRID:grid.11135.37) (ISNI:***) peking university State Key Lab Nucl. Phys. &amp Tech. School of Physics Beijing China (GRID:grid.11135.37) (ISNI:***) Beihang university School of Physics and Nuclear Energy Engineering Beijing China (GRID:grid.64939.31) (ISNI:***) university of Stellenbosch Department of Physics Stellenbosch South Africa (GRID:grid.11956.3a) (ISNI:***)

The convergence for the Imaginary Time Step (ITS) evolution with time step is investigated by performing the ITS evolution for the Schrdinger-like equation and the charge-conjugate Schrdinger-like equation deduced from Dirac equation for the single proton levels of 12C in both the Fermi and Dirac seas. For the guaranteed convergence of the ITS evolution to the "exact" results,the time step should be smaller than a "critical" time step Δtc for a given single-particle level. The "critical" time step Δtc is more sensitive to the quantum numbers |κ| than to the energy of the single-particle level. For the single-particle levels with the same κ,their "critical" time steps are in the same order. For the single-particle levels with similar energy,a relatively small (large) "critical" time step for larger (smaller) |κ| is needed. These conclusions can be used in the future self-consistent calculation to optimize the evolution procedure.

关键词： Dirac equation Schrdinger-like equation Imaginary Time Step method convergence

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PDMS prism-glass optical coupling for surface plasmon resonance sensors based on MEMS technology

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Science china(Information Sciences) 2010年第10期53卷 2144-2158页

作者： GENG ZhaoXin 1,2 , LI Qing 3 , WANG Wei 1 & LI ZhiHong 1 1 Institute of Microelectronics, peking university, beijing 100871, china 2 school of Information engineering, Minzu university of china, beijing 100081, china 3 school of Sciences, Changchun university of Science and Technology, Changchun 130000, china Institute of Microelectronics Peking University school of Information engineering Minzu University of China school of Sciences Changchun University of Science and Technology

A miniaturized surface plasmon resonance (SPR) chip has been developed for biomedical and chem-ical analysis with low cost and high performance. The techniques of bulk silicon micromachining and polymer replication were used to fabricate the Kretschmann SPR sensor composed of a Polydimethylsiloxane (PDMS) prism, a coupling glass and microchannels. The plasmon properties of thin metal films were investigated theoret-ically based on Fresnel analysis, with optical boundary conditions pertaining to the surface plasmon resonance at the gold/water and gold/air interfaces. The theoretical results show that difference in the refractive index (RI) between the PDMS prism and the coupling glass layer affect the precision of the SPR angle and the SPR curve. Meanwhile, the period of the interference fringe attaching on the SPR curve increases with an increase in wavelength and a decrease in the refractive index of the coupling glass layer. The gold thickness of 50 nm is required while employing a fixed incident wavelength of 650 nm, to achieve optimum SPR excitation conditions and the sensor sensitivity. The characteristics of this SPR sensor were evaluated in the angular interrogation mode of employing the incident wavelength of 650 nm in air and water media, respectively. The obtained SPR angles were approximately consistent with the theoretical ones.

关键词： surface plasmon resolance polymer microfluidic PDMS

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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 Department of Mathematics Tsing Hua University Hsinchu China LMAM School of Mathematical Sciences Peking University 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.

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