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Optical observations of Scorpius X-1 in 2008:Evidence of rapid variability

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 143-146页

作者： CAO XiaoFeng1,2,YU WenFei1,YAN Zhen1 & SUN Li1 1 Shanghai Astronomical Observatory,Shanghai 200030,china 2.institute of astrophysics,huazhong normal university,wuhan 430079,china Shanghai Astronomical Observatory Shanghai China institute of astrophysics Huazhong Normal University Wuhan China

Optical observations of Sco X-1 with exposure times around 0.5 s were performed with the 1.56 m telescope of the Shanghai Astronomical Observatory in *** these observations,we studied the fluctuation of the optical flux on three short timescales(5,10,100 s).We found that the standard deviations of fluctuations on these three timescales differ from those of Gaussian distributions by 7 Sigma,5 Sigma and 3 Sigma,*** result suggests that the variations in the intensity on these short timescales differ from pure statistical fluctuations,which,we suggest,is due to the intrinsic variability in the optical emission.

关键词： accretion disks stars:individual(Scorpius X-1) optical:stars

Long-term evolution and gravitational wave radiation of neutron stars with differential rotation induced by r-modes

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Research in Astronomy and astrophysics 2009年第9期9卷 1024-1034页

作者： Yun-Wei Yu Xiao-Feng Cao Xiao-Ping Zheng institute of astrophysics Huazhong Normal University Wuhan 430079 China

In a second-order r-mode theory, Sa and Tome found that the r-mode oscillation in neutron stars （NSs） could induce stellar differential rotation, which naturally leads to a saturated state of the oscillation. Based on a consideration of the coupling of the r-modes and the stellar spin and thermal evolution, we carefully investigate the influences of the differential rotation on the long-term evolution of isolated NSs and NSs in low-mass X-ray binaries, where the viscous damping of the r-modes and its resultant effects are taken into account. The numerical results show that, for both kinds of NSs, the differential rotation can significantly prolong the duration of the r-modes. As a result, the stars can keep nearly a constant temperature and constant angular velocity for over a thousand years. Moreover, the persistent radiation of a quasi-monochromatic gravitational wave would also be predicted due to the long-term steady r-mode oscillation and stellar rotation. This increases the detectability of gravitational waves from both young isolated and old accreting NSs.

关键词： stars: neutron -- stars: evolution -- stars: rotation -- gravitational waves

Energy Efficient Beacon Discovering Scheme for Node Localization in Wireless Sensor Networks

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wuhan university Journal of Natural Sciences 2010年第4期15卷 303-307页

作者： LIU Xinxin1,2, ZHAO Erdun3, CHEN Kun2 1. School of Computer, wuhan university, wuhan 430072, Hubei, china 2. wuhan Digital Engineering Research institute, wuhan 430074, Hubei, china 3. Department of Computer Science, huazhong normal university, wuhan 430079, Hubei, china School of Computer Wuhan University Wuhan Hubei China wuhan Digital Engineering Research institute Wuhan Hubei China Department of Computer Science Huazhong Normal University Wuhan Hubei China

Efficient sensor node localization is a crucial part of many location-dependent applications that utilize wireless sensor networks (WSNs). To cope with the problem of insufficient bea-con node for localization,we design a beacon discovery protocol in this paper that helps the blind node to find beacons nearby and present an energy efficient scheme for the beacon that receives the request from a blind node to adjust its radio range. We obtain the relationship between the mean energy consumption with adjust-ment number by the mathematical analysis. Numerical results show that great energy saving is achieved when the optimal ad-justment number is adopted.

关键词： localization wireless sensor networks energy- efficient radio range adjustment

TiO_2@MgO Core-Shell Film:Fabrication and Application to Dye-Sensitized Solar Cells

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wuhan university Journal of Natural Sciences 2010年第4期15卷 325-329页

作者： LI Bihui, Lü Gang, LUO Lijuan, TANG Yiwen institute of Nano-Science and Technology, huazhong normal university, wuhan 430079, Hubei, china institute of Nano-Science and Technology Huazhong Normal University Wuhan Hubei China

In this study,TiO2@MgO core-shell film was obtained by using a simple chemical bath deposition method to coat a thin MgO film around TiO2 nanoparticles. The core-shell configuration was characterized by X-ray diffractometer (XRD),scanning elec-tron microscopy (SEM),energy dispersive X-ray spectroscopy (EDX),and high-resolution transmission electron microscopy (HRTEM). Lattice fringes were observed for the TiO2 particles,and the MgO shell showed an amorphous structure,revealing a clear distinction between the core and shell materials. Applying the core-shell film as photoanode to the dye-sensitized solar cells (DSSCs),it shows a superior performance compared to the pure TiO2 electrode. Under the illumination of simulated sunlight (75 mW-cm-2),the short circuit photocurrent (Jsc),the open circuit photovoltage (Voc),and the fill factor (fF) are 8.80 mA-cm-2,646 mV,and 0.69,respectively,and the conversion efficiency (η) in-creased by 21.8% (from 4.32% to 5.26%) when dipping for opti-mum condition.

关键词： TiO2@MgO core-shell electrode dye-sensitized solar cell (DSSC)

Behavior of gravity waves with limited amplitude in the vicinity of critical layer

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Chinese Science Bulletin 2002年第18期47卷 1547-1550页

作者： WU Shaoping & Yl Fanwuhan institute of Physics and Mathematics, Chinese Academy of Sciences, wuhan 430071, china Department of Radio Science and Technology, wuhan university, wuhan 430072, china Department of Physics, huazhong normal Univ wuhan institute of Physics and Mathematics Chinese Academy of Sciences Wuhan China Department of Physics Huazhong Normal University Wuhan China Department of Radio Science and Technology Wuhan University Wuhan China

By using the FICE scheme, a numerical simulation of three-dimensional nonlinear propagation of gravity wave packet in a wind-stratified atmosphere is presented. The whole nonlinear propagation process of the gravity wave packet is shown; the propagation behavior of gravity waves in the vicinity of critical layer is analyzed. The results show that gravity waves encounter the critical layer when propagating in the fair winds whose velocities increase with height, and the height of critical layer propagating nonlinearly is lower than that expected by the linear gravity waves theory; the amplitudes of gravity waves increase with height as a whole before gravity waves encounter the critical layer, but the increasing extent is smaller than the result given by the linear theory of gravity waves, while the amplitudes of gravity waves reduce when gravity waves meet the critical layer; the energy of wave decreases with height, especially at the critical layer; the vertical wavelength reduces with the height

关键词： gravity waves critical layer FICE scheme simulation.

Controlled Growth of ZnO Array on FTO Glass Substrate by Electrodeposition

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wuhan university Journal of Natural Sciences 2010年第2期15卷 130-134页

作者： LUO Lijuan, Lü Gang, LI Bihui, CHEN Zhenghua, TANG Yiwen institute of Nano-Science and Technology, huazhong normal university, wuhan 430079, Hubei, china institute of Nano-Science and Technology Huazhong Normal University Wuhan China

In this study, ZnO nanotube and nanorod array films were respectively synthesized directly on F-doped Sn02 glass substrate （FTO） using a direct electrodeposition from a simple aqueous zinc salt solution. The effects of potential value, electro- deposition mode and solution stirring speed on the product morphology were investigated. Controlling the reaction under potentiostatic condition of-0.7 V at stirring speed of 300 r/min, large-scale nanotube arrays perpendicular to the substrate can be synthesized at a low temperature of 70℃. By varying the reaction parameters, we can also obtain ZnO nanorod arrays. The results of X-ray diffraction, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy have been provided to characterize the structure and morphology of the nanotube and nanorod arrays. Experiment results show that the as-obtained ZnO has a single crystalline structure and c-axis oriented direction. The room-temperature photoluminescence spectrum of the ZnO nanotube array film displayed its high crystal property available as a photonic material. Electrodeposition is an effective method to prepare ZnO nanotube array films in quantity.

关键词： electrodeposition ZnO nanotubes nanorods array

UNIQUENESS OF THE POSITIVE SOLUTION FOR SINGULAR NONLINEAR BOUNDARY VALUE PROBLEMS

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Systems Science and Mathematical Sciences 1993年第1期6卷 25-31页

作者： DENG Yinbin CAO Daomin Department of Mathematics,huazhong normal university, wuhan 430070,china wuhan institute of Mathematical Sciences, Academia Sinica, wuhan 430071, china

This paper is concerned with the bounded value problems1/p（t）（p（t）u’）’+f（u）=0, t>0, u’（0）=0, lim t→+∞ u（t）=0,where f（0）=0. Such problems arise in the study of semi-linear elliptic differential equa-tions in Rn. It is shown that the problem has at most one positive solution under appro-priate conditions on f and p. Our result can include the important case that p（t）=fn-1and f（u）=uP-u, where n>1, p>1 are some given constants.

关键词： Uniqueness singular boundary value problem semilinear elliptic equation

Parton Energy Loss with Detailed Balance

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Parton Energy Loss with Detailed Balance

A NEIGHBORHOOD UNION CONDITION FOR PANCYCLIC GRAPHS

湖北省物理学会、武汉物理学会成立70周年庆典暨2002年学术年会

作者： Enke Wang institute of Particle Physics, huazhong normal university, wuhan 430079, china

Introduction.—Recent theoretical studies of parton energy loss have concentrated on gluon radiation induced by multiple scattering in a medium. Such a radiative energy loss demonstrates many interesting properties due to the non-Abelian Landau-Pomeranchuk-Migdal (LPM) interference effect. Since gluons are bosous, there should also be stimulated gluon emission and absorption by the propagating parton because of the presence of thermal

关键词： Parton Energy Loss with Detailed Balance

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Systems Science and Mathematical Sciences 1998年第4期11卷 289-298页

作者： LI Xiangwen(Department of Mathematics, huazhong normal university, wuhan 430070, china)WEI Bing(institute of Systems Science, Academia Sinica, Beijing 100080, china)

Let C be a 2-connected graph on > 2 31 venices. G is called pancyclic if itcontains a cycle of length I for every I such that 3 l n. In this paper we shall prove thatif IN(u) U N(v) Z (2n - 3)/3 for any nonadjacent pa... 详细信息

关键词： Neighborhood union cycle pancyclic graph