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What Can the Redshift Observed in EXO 0748-676 Tell Us?

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Chinese Journal of Astronomy and Astrophysics 2003年第1期3卷 33-37页

作者： Ren-Xin XuDepartment of Astronomy, school of physics, Peking University, Beijing 100871 rxxu@*** Department of Astronomy School of Physics Peking University Beijing 100871 China

The mass-radius relations for bare and crusted strange stars are calculated with the bag model. Comparing these relations with the observed one derived from the redshift of EXO 0748–676, we come to the conclusion that it is incorrect to say that EXO 0748–676 cannot be a strange star. Various strange star models can show that EXO 0748–676 could have a mass of (1.3 ~ 1.7)M☉ and a radius of (8.4 ~ 11.4) km. It is proposed that a proportion of nascent strange stars could be bare and have masses ~ 0.1M☉, and their masses increased over a long period of accretion.

关键词： stars: fundamental parameters dense matter stars: neutron

|m| Partial wave treatment for two-dimensional Coulomb-scattering and Regge pole

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Science China(physics,Mechanics & Astronomy) 2004年第6期47卷 676-684页

作者： WANG Jing & ZENG Jinyan Department of physics,Tsinghua University,Beijing 100084,China school of physics,Peking University,Beijing 100871,China Department of physics Tsinghua University Beijing 100084 China school of physics Peking University Beijing 100871 China

The symmetry and |m| partial-wave analysis for two-dimensional (2D) Coulomb-scattering is investigated. As a function of energyE, the |m| partial-wave scattering amplitudef |m|(θ) is analytically continuated to the, negativeE (complexk) plane, and it is found that the bound state energy eigenvalues (E<0) are just located at the poles off |m|(θ) on the positive imaginaryk axis as is expected. In addition, as a function of |m|,f |m|(θ) is analytically continuated to the complex |m| plane, the bound state energy eigenvalues are just located at the poles off |m|(θ) on the positive real |m| axis.

关键词： two-dimensional Coulomb scattering, |m| partial-wave, Regge pole.

Views on “Principle of limitation of physical quantities and cyclic universe”

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Science China(physics,Mechanics & Astronomy) 2010年第9期53卷 1772-1774页

作者： LI LianGang Department of physics,school of Sciences,Tianjin University,Tianjin 300072,China 1. Department of physics School of Sciences Tianjin University Tianjin 300072 China

This paper presents an analysis of a paper entitled "Principle of limitation of physical quantities and cyclic universe" and proposes different results for some formulae from that *** addition,this paper shows that the principle of limits coupling may lead to an approximation of current theories(i.e.,quantum theory and relativistic theory),which have interesting correlations with the Plank formula and the special theory of relativity.

关键词： principle of limitation of physical quantities limits coupling formulae Plank formula theory of relativity

Study of the structure of unstable nuclei through the reaction experiments

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Science China(physics,Mechanics & Astronomy) 2011年第S1期54卷 1-5页

作者： CAO ZhongXin & YE YanLin State Key Laboratory of Nuclear physics and Technology, school of physics, Peking University, Beijing 100871, China 1. State Key Laboratory of Nuclear physics and Technology School of Physics Peking University Beijing 100871 China

Along with the development of the radioactive nuclear beam facility, the study of the structure of unstable nuclei has progressed rapidly over the last few decades. Due to the weakly binding property, the structure information of the unstable nuclei comes primarily from the scattering or reaction experiments. Therefore it would be very important to understand clearly the reaction mechanism involved in the experiment. We outlined here the major reaction mechanisms which are adequate to the study of unstable nuclei, with the focus on the new phenomena and methods in comparison with those with traditional stable nucleus beam. Especially emphasized are the breakup and knockout reactions, developed as accurate tools for spectroscopy investigation into the nuclear structure with low intensity secondary beam. Couplings of the breakup channel to the elastic scattering and the fusion and transfer reactions are also reviewed.

关键词： binaries: unstable nuclei nuclear structure breakup reaction knockout reaction fusion reaction transfer reaction

Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods

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Journal of Materials Science & Technology 1997年第4期13卷 265-270页

作者： Nobuo Tanaka (Dept. of Applied physics, school of Engineering, Nagoya University, Nagoya, 464-01, Japan) Dept. of Applied physics School of Engineering Nagoya University Nagoya 464-01 Japan

Nanometer-sized metal clusters were prepared inside single crystalline MgO films by vacuum co-deposition of metals and MgO. The atomic structure was studied by high-resolution electron microscopy (HREM) and nm-area electron diffraction. The size of the clusters is ranging from 1 nm to 3 nm without those larger than 5 nm, and most of them have definite epitaxial orientations with the MgO matrix films. The character of the composite films is very much useful for the studies of various kinds of physical properties with anisotroPy. The physical properties such as electric transport, magnetic, optical absorption, sintering and catalytic ones were thus measured on the same samples analyzed by HREM by using high sensitivity apparatus with interest of clarifying the retationship between the atomic structure and physical properties

关键词： Figure Nano Studies of Atomic Structure and Physical Properties of Metal Clusters in MgO by HREM and Nano-probe Methods HREM MgO

Abrupt climate change and collapse of ancient civilizations at 2200BC-2000BC

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Progress in Natural Science:Materials International 2005年第10期15卷 46-52页

作者： WANG Shaowu (Department of Atmospheric Science, school of physics, Peking University, Beijing 100871, China) Department of Atmospheric Science School of Physics Peking University Beijing 100871 China

Plentiful evidence of historical, archaeological and palaeoclimatic studies proved that an abrupt change from wetter to drier climate occurred over the Nile Valley,the Mesopotamia, the Indus Valley and Huanghe River Valley at 2200BC-2000BC. The abrupt change was developed based on the general lowering of temperature in the middle latitudes, and was a strong cold event since the beginning of the Megathermal (8.5-3.0 kaBP). Collapse of Nile civilization appeared at the First Intermediate Period (2181BC-2040BC). Civilization of Mesopotamia began collapse following the disintegration of Akkadian Empire. This process lasted to the foundation of Babylon Kingdom from 2200BC to 1900BC. Indus civilization abruptly fell off at 1800BC. A widespread alternation of archaeological cultures happened in China at ca. 2000BC except only in its central part. Longsheng culture was replaced by the Erlitou culture, which is now acknowledged in China as Xia Culture. Foundation of Xia Dynasty at 2070BC opened a new chapter in the development of Chinese civilization. Studies indicated that abrupt climate change may be caused by the weakening of the Thermohaline Circulation (THC).

关键词： 2200BC-2000BC abrupt climate change collapse of ancient civilization.

A photometric study of the K-type contact binary EI CVn

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Research in Astronomy and Astrophysics 2011年第2期11卷 181-190页

作者： Yuan-Gui Yang school of physics and Electronic Information,Huaibei Normal University,Huaibei 235000,China school of physics and Electronic Information Huaibei Normal University Huaibei 235000 China

We present charge-coupled device （CCD） photometry for the short-period K-type binary EI CVn,observed on 2009 February 28 at the Xinglong Station of National Astronomical Observatories,Chinese Academy of *** using the Wilson-Devinney program,the photometric solution was first deduced from our V R *** results show that EI CVn is a W-type weak-contact binary with a mass ratio of qph=0.2834（±0.0010） and an overcontact degree of f=20.0%（±0.7%）.The distorted light curves were modeled by a dark spot on the cool primary component,whose area was up to 1.9% of the area of the *** on the period analysis,it is found that there exists a weak secular decrease at a rate of dP/dt= 3.11（±0.03） × 10-7 d yr-1,which may be attributed to mass transfer from the primary to the *** mass transfer occurring,the separation between both components will shrink,which may cause the degree of overcontact to ***,the weak-contact binary EI CVn may evolve into a deep-contact configuration.

关键词： stars: binaries: close -- stars: binaries: eclipsing -- stars: individual: EICVn

Optical waveguides in LiNbO_3 and stoichiometric LiNbO_3 crystals by proton exchange

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Science China(physics,Mechanics & Astronomy) 2008年第10期51卷 1479-1488页

作者： LI ShiLing College of physics and Engineering, Qufu Normal University, Qufu 273165, China school of physics and Microelectronics, Shandong University, Jinan 250100, China 1. College of physics and Engineering Qufu Normal University Qufu 273165 China 2. school of physics and Microelectronics Shandong University Jinan 250100 China

The formation of optical planar waveguides in LiNbO3 and stoichiometric LiNbO3 crystals by proton exchange was reported. The prism-coupling method was used to characterize the dark-line spectroscopy at the wavelength of 633 and 1539 nm, re-spectively. The mode optical near-field outputs from proton-exchanged LiNbO3 and SLN waveguides at 633 nm were presented. The mode field from stoichiometric LiNbO3 (SLN) waveguide is lighter and more uniform than that from LiNbO3 waveguide, which means the quality of the waveguide in SLN crystal is better than that of the LiNbO3 waveguide. For proton-exchanged LiNbO3 waveguides, the evo-lution of the refractive index profile with annealing was presented. The disorder profiles of Nb atoms in proton-exchanged LiNbO3 waveguides were obtained by Rutherford backscattering/channeling technique. It is shown that the longer the exchange time, the larger the displacement of Nb atoms.

关键词： optical waveguide proton exchange LiNbO3 crystal stoichiometric LiNbO3 crystal

Design of an MRI quadrature-data acquisition card

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Progress in Natural Science:Materials International 2006年第3期16卷 255-259页

作者： JIANG Zhongde, ZU Donglin and GU Xiaofang (Institute of Heavy Ion physics, Beijing Key Laboratory of Medical physics & Engineering, school of physics, Peking University,Beijing 100871, China) [a]Institute of Heavy Ion physics Beijing Key Laboratory of Medical Physics & Engineering School of Physics Peking University Beijing China

A design of a quadrature-data acquisition card based on peripheral component interconnect (PCI) bus for mini-type magnetic resonance imaging (MRI) system is reported. It uses two high speed analog-to-digital converters (ADCs) to sample the MRI signals and two static random access memories (SRAMs) to store the data which will be read to the computer by PCI bus after sampling. All the logic control signals on the card are generated by the field programmable gate array (FPGA). The software Foundation3.1 is used to design the FPGA and achieve useful result after simulating and implementing. The card has some merits that normal commercial cards do not have. For example, the sampling parameters can be varied according to different pulse sequences.

关键词： MRI data acquisition FPGA PCI bus.