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A Systematic Study on Scaling Law of Spiral Waves

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Communications in Nonlinear Science and Numerical Simulation 1999年第3期4卷 3-5页

作者： Shufeng BAI,Yan LI and Qi QUYANG(These auhors attribute equally to this article)(department of physics,peking {3.,beijing 100871,china) department of physics Peking University Beijing 100871 China

Pactedsformationfarfromthermodynamicsequilibriumareubiquitousintheworld,typicalofwhichisthespiralpattern,***-diffusionsystems,***,whOSetiporbitsaci... 详细信息

Pactedsformationfarfromthermodynamicsequilibriumareubiquitousintheworld,typicalofwhichisthespiralpattern,***-diffusionsystems,***,whOSetiporbitsaci...

关键词： spirals non-linear waves scaling law

Structure and optical properties of the Ge and Sn quantum-dots

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Nuclear Science and Techniques 2000年第2期11卷 119-123页

作者： HAN Zhao-Hui ZHAO Zi-Qiang(Institute of Heavy Ion physics, technical physics Depariment,{3.,beijing 100871) 北京大学北京 100871

Embedded cluster samples Ge:CaF2 and Sn:CaF2 with different sizes less than 8nm were produced and their optical properties were *** diffraction reveals that the clusters’ structures are crystallites and compared with the bulk Germanium and Stannum, lattice constants expand about 4.7% in the case of Ge:CaF2 and 5.2% of Sn:CaF2. Optical absorption and photoluminescence spectra of these samples show good agreement with the Quantum-Confinement-Effect(QCE) theory. With the decreasing of the cluster’s size, the energy gap broadens and the absorption edge blueshift is observed, and the absorption edge also shifts with the changing of the fraction of Sn and Ge. The XPS results show that in the cluster state,the binding energy becomes higher.

关键词：锗微晶锡微晶半导体 X射线光电子能谱结构光学性质电子衍射氟化钙

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,{3. 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

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 Laboratory of Nuclear physics and Technology, peking university,{3., china 2 department of physics, Guangxi university, Nanning 53.004, china 1. School of physics and State Key Laboratory of Nuclear physics and Technology Peking University Beijing 100871 China 2. department of physics Guangxi University Nanning 530004 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

“Einstein Moon”,“Schrdinger Cat”,and “Quantity in Phase Space”—About Quantum Measurement(Ⅰ)

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Communications in Theoretical physics 2004年第6期 833-836页

作者： REN De-Ming department of physics,peking {3.,beijing 100871,china departmentofphysics PekingUniversityBeijing100871China

Generalizing the idea involved in a previous paper [***.(beijing,china) 41 (2004)685],"quantity in phase space" is *** starting from quantum mechanics,with standard criteria,thedisappearing of interference in a macroscopic system is explicitly *** the confusions involved in "the EinsteinMoon" and "the Schrdinger Cat" are clarified,at least principally.

关键词： quantum measurement quantum communication

Optical data storage in nonphotosensitive media by femtosecond laser pulses

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Progress in Natural Science:Materials International 2007年第8期17卷 877-880页

作者： Li Yan~(**) Liu Dayong Dou Yanping Yang Hong and Gong Qihuang (State Key Laboratory for Mesoscopic physics and department of physics,{3. university,beijing 100871,china) State Key Laboratory for Mesoscopic physics Department of Physics Peking University Beijing 100871 China

Ultrashort lasers have become powerful tools by inducing extremely nonlinear effects in a wide variety of materials. Femtosecond laser data storage in non-photosensitive media is promising for its high density and fast *** reviewed the progress of three types of femtosecond laser storage in transparent materials:three-dimensional bit-oriented storage by micro-voids,holographic data storage by two beam interference and storage by computer-generated holograms.

关键词： femtosecond laser three-dimensional data storage holographic data storage computer-generated hologram

Status of study on biological and toxicological effects of nanoscale materials

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Science china Chemistry 2005年第5期48卷 385-394页

作者： WANG Bing1, FENG Weiyue1, ZHAO Yuliang1, XING Gengmei1, CHAI Zhifang1, WANG Haifang2 & JIA Guang3.1. Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials (Nanosafety Lab), Institute of High Energy physics, Chi-nese Academy of Sciences, beijing 100049, china 2. College of Chemistry and Molecular Engineering,{3., beijing 100871, china 3. department of Occupational and Environmental Health Sciences, School of Public Health,{3., beijing 100083. china 1. Laboratory for Bio-Environmental Health Sciences of Nanoscale Materials (Nanosafety Lab) Institute of High Energy Physics Chinese Academy of Sciences 100049 Beijing China 2. College of Chemistry and Molecular Engineering Peking University 100871 Beijing China 3. department of Occupational and Environmental Health Sciences School of Public Health Peking University 100083 Beijing China

Because the physical and chemical properties of nanosized materials mostly differ from the existing microsized materials, their potential impacts on human health and the envi-ronment will be topics under the serious discussions in press and in a number of international scientific journals. We analyze and summarize the existing data of the experimental study on the biological activities and adverse effects of nanoscale materials/particles including single wall carbon nanotubes, multi wall carbon nanotubes, titanium oxide and iron powders. Though some biological behaviors of nanoscale materials observed cannot be understood on the basis of the current knowledge, as the existing data are mostly preliminary, it is too early to make some ex-clusive conclusions on biological activities (or the toxicity) of any of nanoscale materials. The experimental techniques, the current topics, and the future research directions for this new re-search field are also discussed.

关键词： nanomaterials, single wall carbon nanotubes, multi wall carbon nanotubes, titanium oxide and iron, biological activity and toxicological effect.

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,{3. department of Radiology, The First Affiliated Hospital of peking university, beijing 10003.,{3.) 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.

Three types of maximally entangled states for a two-particle system

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Science china(physics,Mechanics & Astronomy) 2004年第1期47卷 36-41页

作者： RUAN Manqi, XU Gang & ZENG Jinyan department of physics, Tsinghua university, {3. 100084, china department of physics, peking university, beijing 100871, china Correspondence should be addressed to Zeng Jinyan (email: jyzeng@***) Received June 16, 2003 1. department of physics Tsinghua University 100084 Beijing China 2. department of physics Peking University 100871 Beijing China

For a two-particle (spin 1/2) system, three fundamental forms of complete sets of commuting observables (CSCO) composed of two-body operatorsσ 1α σ 2α are given. The corresponding simultaneous eigenstates constitute three types of maximally entangled states, one of which is the well known Bell basis. This paper discusses the possible pairs of spin observables whose simultaneous measurement outcomes are definitely correlated in probabilistic fashion.

关键词： spin entangled state, complete set of commuting observables, two-body operator.