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Petrogenesis of Songshugou dunite body in the Qinling orogenic belt, Central china: Constraints from geochemistry and melt inclusions

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Science china Earth Sciences 2005年第8期48卷 1146-1157页

作者： SU Li1,2, SONG Shuguang3.& ZHOU Dingwu1 1. key laboratory of Continental Dynamics of the Ministry of Education, Department of Geology, Northwestern university, Xi’an 710069, {3. 2. The Geological lab Center, {3. university of Geosciences (beijing), beijing 100083. {3. 3. key laboratory of Orogenic Belts of the Ministry of Education, Department of Geology, peking university, {13., {3. key laboratory of Continental Dynamics of the Ministry of Education Department of Geology Northwestern University Xi’an China The Geological lab Center China University of Geosciences (Beijing)Beijing China key laboratory of Orogenic Belts of the Ministry of Education Department of Geology Peking University Beijing China

The Songshugou dunite body, which occupies an area of about 20 km2, is the largest ultramafic massif in the eastern Qinling orogenic belt, Central china. The major compo-nent of this body is dunitic rocks including mylonitic dunite and coarse-grained dunite; they oc-cupy about 95 vol% of the total body. Petrography, mineral composition, major and trace ele-ments and primitive melt inclusions have been investigated in this paper; all revealed that this dunite body is the product of melt-rock interaction by porous percolation flow. In comparison with dunite sills or veins in harzburgite from the basal part of Oman ophiolite, this dunite body is characterized by lower contents of Al2O3. CaO and HREE but higher content of highly incom-patible elements and Zr and Hf. The LREE enriched patterns and primitive mantle normalized spidergrams of trace elements are also different from the Oman dunite. Combining with melt in-clusions observed in olivines, we conclude that this dunite body is the product of large- scale porous percolation flow of high-MgO melts within depleted mantle peridotites. The high-MgO magma, in essence, was most probably produced at the hot head of an upwelling mantle plume. The occurrence of the Songshugou dunite body is closely associated with the activity of mantle super-plume in Neo-Proterozoic era in the Yangtze Craton.

关键词： Songshugou dunite body, geochemistry, melt inclusion, mantle plume, Qinling orogenic belt.

X-ray flares of γ-ray bursts: Quakes of solid quark stars?

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Science china(Physics,Mechanics & Astronomy) 2009年第2期52卷 315-320页

作者： XU RenXin1 & LIANG EnWei2 1 school of Physics and state key {3.oratory of nuclear Physics and technology, peking university, beijing 100871, china 2 Department of Physics, Guangxi university, Nanning 53.004, china school of Physics and state key {3.oratory of nuclear Physics and technology Peking University Beijing China Department of Physics Guangxi University Nanning China

A star-quake model is proposed to understand X-ray flares of both long and short γ-ray bursts (GRBs) in a solid quark star regime. Two kinds of central engines for GRBs are available if pulsar-like stars are actually (solid) quark stars, i.e., the SNE-type GRBs and the SGR-type GRBs. It is found that a quark star could be solidified about 103.to 106 s later after its birth if the critical temperature of phase transi- tion is a few Metga-electron-volts, and then a new source of free energy (i.e., elastic and gravitational ones, rather than rotational or magnetic energy) could be possible to power GRB X-ray flares.

关键词： γ-rays bursts: X-rays neutron stars elementary particles

A novel endorectal RF coil for high resolution MRI and spectroscopy of the prostate

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Progress in Natural Science:Materials International 2005年第5期15卷 472-476页

作者： ZHANG Hongjie 1,2, SONG Xiaoyu1, WANG Xiaoying3. XU Pingfang1 and BAO Shanglian1*(1. beijing key laboratory of Medical Physics & Engineering, {3., beijing 100871, china 2. Navy General Hospital, beijing 10003., china 3. {3. First Hospital, beijing 10003., china) beijing key lab. of Med. Phys. and Eng. Peking Univ. Beijing 100871 China Navy General Hospital Beijing 100037 China peking Univ. First Hospital Beijing 100034 China

The diagnosis of prostate diseases by magnetic resonance imaging (MRI) in vivo is sometimes difficult for the lower signal to noise ratio (SNR). To increase the SNR of the prostate image, we designed a RF coil that can be inserted into rectum and was named endorectal coil. The properties of RF coil were evaluated using a network analyzer. Moreover the images and spectroscopy of a special phantom were acquired and the results were compared to those of the commercial TORSO coil (G.E. Medical Systems, USA). Our coil gave a significantly higher SNR at the region of interest (ROI). The achieved high local SNR and resulting high spatial resolution would add more anatomic and biochemical information to the diagnosis of prostate diseases.

关键词： MRI RF coil endorectal coil.

Positioning localities from spatial assertions based on Voronoi neighboring

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Science china(Technological Sciences) 2010年第S1期53卷 143-149页

作者： GONG YongXi 1,2,3.LI GuiCai 1,LIU Yu 2 & YANG Jian 1 1 Shenzhen key lab of Recycling Economy,peking university Shenzhen Graduate {3.,Shenzhen 518055,china 2Institute of Remote Sensing and Geographical Information Systems,peking university,beijing 100871,china 3.ollege of Urban and Environmental Science,peking university,beijing 100871,china Shenzhen key lab of Recycling Economy Peking University Shenzhen Graduate School Shenzhen China Institute of Remote Sensing and Geographical Information Systems Peking University Beijing China College of Urban and Environmental Science Peking University Beijing China

With the rapid development of Internet,much spatial information contained in non-structured or semi-structured documents is available on the World Wide *** such documents,localities are always textually described using spatial relationships and named places,instead of numerical ***,extracting positional information from locality descriptions is an important *** this paper,we bridge two aspects of locality descriptions,namely generating locality descriptions and positioning localities,and provide a method to compute probability density according to the selection probability of a reference object to describe the position of the target *** operation on uncertainty field is used to deal with locality description involving multiple reference *** metrics are introduced to measure the results of positioning *** choose the mixed selection probability function based on Euclidean distance and Voronoi stolen-area to compute probability density ***,we use three cases to demonstrate the proposed methods.

关键词： geographic information science positioning locality Voronoi neighboring probability density function

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 {3. lab Nucl. Phys. & Tech.,school of Physics,peking university,beijing 100871,china 3.5} 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 state key lab Nucl. Phys. & Tech. School of Physics Peking University Beijing China school of Physics and nuclear Energy Engineering Beihang University Beijing China Department of Physics University of Stellenbosch Stellenbosch South Africa

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

Optimization of the imaginary time step evolution for the Dirac equation

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Science china(Physics,Mechanics & Astronomy) 2011年第2期54卷 231-235页

作者： LI FangQiong1,ZHANG Ying2,LIANG HaoZhao2,3.& MENG Jie4,2,5 1Guizhou university for Nationalities,Guiyang 550025,china 2state {3. lab nuclear Physics & technology,school of Physics,peking university,beijing 100871,china 3.nstitut de Physique Nucle’aire,IN2P3.CNRS and Universite’ Paris-Sud,F-91406 Orsay Cedex,France 4school of Physics and nuclear Energy Engineering,Beihang university,beijing 100191,china 5Department of Physics,university of Stellenbosch,Stellenbosch,South Africa Guizhou university for Nationalities Guiyang China state key lab {3. Physics & technology School of Physics Peking University Beijing China Institut de Physique Nucléaire IN2P3-CNRS and Université Paris-Sud Orsay Cedex France school of Physics and nuclear Energy Engineering Beihang University Beijing China Department of Physics University of Stellenbosch Stellenbosch South Africa

Taking the single neutron levels of 12C in the Fermi sea as examples,the optimization of the imaginary time step(ITS) evolution with the box size and mesh size for the Dirac equation is *** the weakly bound states,in order to reproduce the exact single-particle energies and wave functions,a relatively large box size is *** long as the exact results can be reproduced,the ITS evolution with a smaller box size converges faster,while for both the weakly and deeply bound states,the ITS evolutions are less sensitive to the mesh ***,one can find a parabola relationship between the mesh size and the corresponding critical time step,i.e.,the largest time step to guarantee the convergence,which suggests that the ITS evolution with a larger mesh size allows larger critical time step,and thus can converge faster to the exact *** conclusions are very helpful for optimizing the evolution procedure in the future self-consistent calculations.

关键词： Dirac equation Schrdinger-like equation imaginary time step method convergence

Magnetic moments of ^(3.)Mg in the time-odd relativistic mean field approach

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Science china(Physics,Mechanics & Astronomy) 2009年第10期52卷 1586-1592页

作者： LI Jian1,ZHANG Ying1,YAO JiangMing1 & MENG Jie1,2 1 school of Physics,state key {3.oratory of nuclear Physics and technology,peking university,beijing 100871,china 2 school of Physics and nuclear Energy Engineering,Beihang university,beijing 100191,china school of Physics State Key Laboratory of Nuclear Physics and Technology Peking University Beijing China school of Physics and nuclear Energy Engineering Beihang University Beijing China

The configuration-fixed deformation constrained relativistic mean field approach with time-odd component has been applied to investigate the ground state properties of 3.Mg with effective interaction *** ground state of 3.Mg has been found to be prolate deformed,β2=0.23.with the odd neutron in 1/2[3.0] orbital and the energy -251.85 MeV which is close to the data -252.06 *** magnetic moment -0.913. μN is obtained with the effective electromagnetic current which well reproduces the data -0.7456 μN self-consistently without introducing any *** energy splittings of time reversal conjugate states,the neutron current,the energy contribution from the {3. magnetic potential,and the effect of core polarization are discussed in detail.

关键词： magnetic moment binding energy time-odd component configuration-fixed deformation constrained calculation relativistic mean field theory

Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

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Science china Earth Sciences 2010年第3期53卷 317-326页

作者： XIAO FuLiang1,2, ZONG QiuGang3. SU ZhenPeng4, TIAN Tian3.& ZHENG HuiNan4 1 school of Physics and Electronic Sciences, Changsha university of Science and technology, Changsha 410004, {3. 2 state key laboratory of Space Weather, Chinese Academy of Sciences, beijing 100190, {3. 3.Institute of Space Physics and Applied technology, peking university, beijing 100871, {3. 4 CAS key lab for Basic Plasma Science, school of Earth and Space Sciences, university of Science and technology of {3., Hefei 23.026, {3. school of Physics and Electronic Sciences Changsha University of Science and Technology Changsha China state key laboratory of Space Weather Chinese Academy of Sciences Beijing China Institute of Space Physics and Applied technology Peking University Beijing China CAS key lab for Basic Plasma Science School of Earth and Space Sciences University of Science and Technology of China Hefei China

Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3. evolution of phase space density from our currently developing 3. code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

关键词： wave-particle interaction VLF/ELF waves energetic electrons acceleration and loss inner magnetosphere

Shape phase transitions in nuclei:Effective order parameters and trajectories

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Science china(Physics,Mechanics & Astronomy) 2011年第S1期54卷 88-97页

作者： ZHANG Yu1,2, HOU ZhanFeng2 & LIU YuXin2,3.1Department of Physics, Liaoning Normal university, Dalian 116029, china 2Department of Physics and the state {3. laboratory of nuclear Physics and technology, peking university, beijing 100871, china 3.enter of Theoretical nuclear Physics, National laboratory of Heavy Ion Accelerator, Lanzhou 720000, china Department of Physics Liaoning Normal University Dalian China Department of Physics and the state key laboratory of {3. Physics and technology Peking University Beijing China Center of Theoretical nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou China

We analyze systematically the effective order parameters in nuclear shape phase transition both in experiments and in the interacting boson model. We find that energy ratios and B(E2) ratios can distinguish the first from the second-order phase transition in theory above a certain boson number N (about 50), but in experiments, only those quantities, such as E(L1+)/E(02+) and B(E2; (L+2)1 → L1)/B(E2; 21 → 01), etc., of which the monotonous transitional behavior in the second-order phase transition is broken in the first order phase transition independent of N, are qualified as the effective order parameters. By implementing the originally proposed effective order parameters and the new ones, we find that the isotones with neutron number Nn = 62 are a trajectory of the second order phase transition. In addition, we predict that the transitional behavior of isomer shifts of Xe, Ba isotopes and Nn = 62 isotones is approximately monotonous due to the finiteness of nuclear system.

关键词： nuclear shape phase transition interacting boson model effective order parameter finite particle number effect transition trajectory