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Simulation of g factor for size optimization and coupling in phased array coil design

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Progress in Natural Science:Materials International 2006年第2期16卷 120-124页

作者： SONG Xiaoyu, ZHANG Hongjie, WANG Le, BAO Shanglian, SUN Yanrong and ZU Donglin (Beijing Key Laboratory of Medical physics & Engineering, Peking University, Beijing 100871, China physics school, Peking University, Beijing 100871, China) [a]Beijing Key Labaratory of Medical physics & Engineering Peking University Beijing China [b]physics school Peking University Beijing China

The effect of geometric parameters of the coil element in an array on signal-to-notse ratio (SNR) and g factor of parallel imaging are analyzed, and the optimal parameters for the maximal SNR and minimal g factor are also given in this paper. In addition, the effects of coupling on SNR and g factor have been analyzed. The test results indicate that g factor for parallel imaging is greatly increased and SNR is decreased for coupling. According to the optimization, a six-channel parallel coil has been designed for torso imaging.

关键词： MRI phased array coil SENSE parallel imaging.

Wavelength and oscillator strength of dipole transition 1s^22p—1s^2nd for Mn^(22+) ion

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Science China(physics,Mechanics & Astronomy) 2008年第11期51卷 1633-1637页

作者： WANG ZhiWen, WANG YaNan, HU MuHong, LI XinRu & LIU Ying school of physics and Electronic Technology, Liaoning Normal University, Dalian 116029, China 1. school of physics and Electronic Technology Liaoning Normal University Dalian 116029 China

The transition energies, wavelengths and dipole oscillator strengths of 1s22p-1s2nd (3≤n≤9) for Mn22+ ion are calculated. The fine structure splittings of 1s2nd (n≤9) states for this ion are also evaluated. In calculating energy, the higher-order relativistic contribution is estimated under a hydrogenic approximation. The quantum defect of Rydberg series 1s2nd is determined according to the quantum defect theory. The results obtained in this paper excellently agree with the experi-mental data available in literatures.

关键词： Mn22+ ion transition energy fine structure splitting quantum defect oscillator strength

b→ssin a Vector Quark Model

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Communications in Theoretical physics 2005年第11期44卷 887-890页

作者： CAI Hai-Ying ZHANG Da-Xin Institute of Theoretical physics,school of physics,Peking University,Beijing 100871,China

The rare decay b→ss(?) is studied in a vector quark model by adding the contributions from exoticvector-like *** find that the contribution from box diagrams amounts to 10-9in the branching ratio,while theZ-mediated ... 详细信息

关键词： rare decay vector-like quarks

Optimal 1 → M phase-covariant cloning in three dimensions

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Chinese physics B 2014年第7期23卷 269-273页

作者：张文海余龙宝曹卓良叶柳 Department of physics Huainan Normal University school of Electronic and Information Engineering Hefei Normal University school of physics and Material Science Anhui University

In this paper, we derive the explicit transformations of the optimal 1→3, 4, 5 phase-covariant cloning in three dimensions, and then generalize them to the cases of 1 → M = 3n, 3n ＋ 1, 3n ＋ 2 （n ≥ 1 integer） cl... 详细信息

关键词： quantum cloning universal quantum cloning phase-covariant cloning

Phase reaction of Au/Sn solder bonding for GaN-based vertical structure light emitting diodes

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Science China(Technological Sciences) 2010年第2期53卷 301-305页

作者： TIAN PengFei, SUN YongJian, CHEN ZhiZhong, QI ShengLi, DENG JunJing, YU TongJun, QIN ZhiXin & ZHANG GuoYi State Key Laboratory for Artificial Microstructure and Mesoscopic physics, school of physics, Peking University, Beijing 100871, China 1. State Key Laboratory for Artificial Microstructure and Mesoscopic physics School of Physics Peking University Beijing 100871 China

Au/Sn solder bonding on Si substrates was used to fabricate the GaN-based vertical structure light emitting diodes (VSLEDs). The phase reaction of Au/Sn solder under different bonding conditions was investigated by the measurement of electron back scattering diffraction (EBSD), and the characteristics of VSLED were analyzed by scanning acoustic microscope (SAM), Raman scattering, current-voltage (I-V) and light output-current (L-I) curves. After the bonding process, horizontal stripes of Au/Sn phase (δ phase) and Au5Sn phase (ζ phase) were redirected to vertical stripes, and δ phase tended to move to the solder joint. Sn interstitial diffusion led to the distribution of δ phase and voids in Au/Sn solder, which could be seen in SAM and SEM images. Vertical distribution of the δ phase and ζ phase with proper voids in the Au/Sn bonding layer showed the best bonding quality. Good bonding quality led to little shift of the E2-high mode of Raman spectra peak in GaN after laser lift off (LLO). It also caused more light extraction and forward bias reduction to 2.9 V at 20 mA.

关键词： GaN LED bonding Au/Sn phase

The low-lying rotational bands of the neutron-rich nucleus ^(172)Tm

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Science China(physics,Mechanics & Astronomy) 2009年第10期52卷 1542-1547页

作者： CHEN BaoRen1,LI Tao1 & LIU ShuXin1,2 1 school of physics,Peking University,Beijing 100871,China 2 Center of Theoretical Nuclear physics,National Laboratory of Heavy Ion Collisions,Lanzhou 730000,China school of physics Peking University Beijing 100871 China Center of Theoretical Nuclear physics National Laboratory of Heavy Ion Collisions Lanzhou 730000 China

The microscopic mechanism of four experimentally observed bands in 172Tm is investigated using the particle-number conserving method of the cranked shell model with monopole and quadrupole paring *** experimental results,including the moments of inertia and angular momentum alignments of four bands in 172Tm are reproduced well by the particle-number conserving *** ω variation of the occupation probability of each cranked orbital and the contribution to moment of inertia from each cranked orbital are *** unobserved low-lying bands of 2-quansiparticles in 172Tm are predicted.

关键词： neutron-rich nucleus rare earth rotational band

Scheme for Controlled Dense Coding via Cavity Decay

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Communications in Theoretical physics 2007年第7期48卷 48-52页

作者： YANG Rong-Can LI Hong-Cai LIN Xiu HUANG Zhi-Ping school of physics and OptoElectronic Technology,Fujian Normal University,Fuzhou 35007,China school of physics and OptoElectronic Technology Fujian Normal University

A scheme for controlled dense coding via cavity decay is *** the scheme,two degenerate groundstates of six-level atoms are used as the storage qubits and the leaky photons act as flying *** system isrobust against atomic spontaneous emissions and decoherence of cavity *** the successful probability is nearly1 with quantum nondemolition parity detectors and photon *** scheme may be realized based on currenttechnologies.

关键词： controlled dense coding cavity decay quantum nondemolition parity detectors

Study of the starting pressure gradient in branching network

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Science China(Technological Sciences) 2010年第4期53卷 2397-2403页

作者： LI Yan & YU BoMing school of physics,Huazhong University of Science and Technology,Wuahn 430074,China 1. school of physics Huazhong University of Science and Technology Wuahn 430074 China

In order to increase the production of oil in low permeability reservoirs with high efficiency,it is necessary to fully understand the properties and special behaviors of the reservoirs and correctly describe the flow in the *** paper applies the branching network mode to the study of the starting pressure gradient of nonlinear Newtonian fluid (Bingham fluid) in the reservoirs with low permeability based on the fact that the fractured network may exist in the *** proposed model for starting pressure gradient is a function of yield stress,microstructural parameters of the *** proposed model may have the potential in further exploiting the mechanisms of flow in porous media with fractured network.

关键词： Bingham fluid flow branching network starting pressure gradient

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The effects of relative density of metal foams on the stresses and deformation of beam under bending

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Acta Mechanica Sinica 2007年第4期23卷 409-414页

作者： Aiyu Zhu Tianyou Fan Department of Mathematics,school of Science,Beijing Institute of Technology,P.O.Box 327,Beijing 100081,China Department of physics,school of Science,Beijing Institute of Technology,P.O.Box 327,Beijing 100081,China Department of Mathematics School of Science Beijing Institute of Technology P. O. Box 327 Beijing 100081 China Department of physics School of Science Beijing Institute of Technology P. O. Box 327 Beijing 100081 China

The exact analytic solution of the pure bending beam of metallic foams is given. The effects of relative density of the material on stresses and deformation are revealed with the Triantafillou and Gibson constitutive law （TG model） taken as the analysis basis. Several examples for individual foams are discussed, showing the importance of compressibility of the cellular materials. One of the objects of this study is to generalize Hill＇s solution for incompressible plasticity to the case of compressible plasticity, and a kinematics parameter is brought into the analysis so that the velocity field can be determined.

关键词： Metal foams - Relative density Compressible plasticity Constitutive law - TG model