The Influence of Guiding Field on Low-frequency Electromagnetic Instabilities in Collisionless Current Sheets

This work investigates the effect of guiding field on low-frequency electromagnetic instabilities in collisionless current sheets using the dispersion relation obtained in the collisionless and compressible magnetohydrodynamic model. The results in the following three cases show that the guiding field can strongly affect the 3-dimensional propagating disturbed waves. (1) On the middle plane of the current sheet (z = 0), if there is no guiding field, then no instability is observed. But if there a guiding field, then instability can take place. (2) Near the middle plane of the current sheet (z = 0.2), the current sheet becomes unstable. With increasing the intensity of the guiding field, the instability grows obviously. The wave mode may be whistler or low-hybrid wave. (3) Near the edge of the current sheet (z = 0.8), the guiding field exhibits no evident effect and the unstable wave mode is a quasi-parallel whistler wave.     

Imaging Spectropolarimetry of Ti I 2231 nm in a Sunspot

Spectro-polarimetric observations at 2231 nm were made of NOAA 10008 near the west solar limb on 29 June 2002 using the National Solar Observatory McMath–Pierce Telescope at Kitt Peak and the California State University Northridge – National Solar Observatory infrared camera. Scans of spectra in both Stokes I and Stokes V were collected; the intensity spectra were processed to remove strong telluric absorption lines, and the Stokes V umbral spectra were corrected for instrumental polarization. The sunspot temperature is computed using the continuum contrast and umbral temperatures down to about 3700 K are observed. A strong Tii line at 2231.0 nm is used to probe the magnetic and velocity fields in the spot umbra and penumbra. Measurements of the Tii equivalent width versus plasma temperature in the sunspot agree with model predictions. Zeeman splitting measurements of the Stokes I and Stokes V profiles show magnetic fields up to 3300 G in the umbra, and a dependence of the magnetic field on the plasma temperature similar to that which was seen using Fei 1565 nm observations of the same spot two days earlier. The umbral Doppler velocity measurements are averaged in 16 azimuthal bins, and no radial flows are revealed to a limit of ±200 m s^–1. A Stokes V magnetogram shows a reversal of the line-of-sight magnetic component between the limb and disk center sides of the penumbra. Because the Tii line is weak in the penumbra, individual spectra are averaged in azimuthal bins over the entire penumbral radial extent. The averaged Stokes V spectra show a magnetic reversal as a function of sunspot azimuthal angle. The mean penumbral magnetic field as measured with the Stokes V Zeeman component splitting is 1400 G. Several weak spectral lines are observed in the sunspot and the variation of the equivalent width versus temperature for four lines is examined. If these lines are from molecules, it is possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from OH, while the line at 2232.21 nm may originate from CN.     

LAMOST CCD camera-control system based on RTS2

The Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST) is the largest existing spectroscopic survey telescope, having 32 scientific charge-coupled-device(CCD) cameras for acquiring spectra. Stability and automation of the camera-control software are essential, but cannot be provided by the existing system. The Remote Telescope System 2 nd Version(RTS2) is an open-source and automatic observatory-control system. However, all previous RTS2 applications were developed for small telescopes. This paper focuses on implementation of an RTS2-based camera-control system for the 32 CCDs of LAMOST. A virtual camera module inherited from the RTS2 camera module is built as a device component working on the RTS2 framework. To improve the controllability and robustness, a virtualized layer is designed using the master-slave software paradigm, and the virtual camera module is mapped to the 32 real cameras of LAMOST. The new system is deployed in the actual environment and experimentally tested. Finally, multiple observations are conducted using this new RTS2-frameworkbased control system. The new camera-control system is found to satisfy the requirements for automatic camera control in LAMOST. This is the first time that RTS2 has been applied to a large telescope, and provides a referential solution for full RTS2 introduction to the LAMOST observatory control system.     

Hard X-ray Source Distributions on EUV Bright Kernels in a Solar Flare

We explore the hard X-ray source distributions of an C1.1 flare occurred on 14 December 2007. Both Hinode/EIS and RHESSI observations are used. One of EIS rasters perfectly covers the double hard X-ray footpoints, where the EUV emission appears strong from the cool line of He ii (log T=4.7) to the hot line of Fe xvi (log T=6.4). We analyze RHESSI X-ray images at different energies and different times before the hard X-ray maximum. The results show a similar topology for the time-dependent source distribution (i.e. at 14:14:35 UT) as that for energy-dependent source distribution (i.e. at a given energy band of 6 – 9 keV) overlapped on EUV bright kernels, which seems to be consistent with the evaporation model.     

Multi-band optical variability of BL Lac object OQ 530

Historical optical data are combined on the BL Lac object OQ 530.Verifying the existence of correlations among the flux variations in different bands serves as an important tool to investigate emission processes.To examine the possible existence of a lag between variations in different optical bands from this source,a statistical analysis is performed through the discrete correlation function(DCF)method and the z-transformed discrete correlation function(ZDCF)method.Monte Carlo simulations called"flux redistribution/random subset selection"(FR/RSS)are performed to obtain statistically meaningful values for the cross-correlation time lags and their related uncertainties.The analysis confirms that the variations in different optical light curves are strongly correlated,with zero-lag within the errors.Long term variability of color indexes is also analyzed.The result suggests a strong correlation between color index and brightness.A clear bluer-when-brighter chromatism is found,in the sense that the spectrum steepens as the brightness decreases.     

Dynamic response of pavements on poroelastic half-space soil medium to a moving traffic load

This paper presents an investigation of the steady-state response of pavement systems subjected to a moving traffic load. The traffic loads are simulated by four rectangular load pressures, and the rigid and flexible pavement systems are regarded as an infinite plate resting on a poroelastic half-space soil medium. The contact surface between the plate and the poroelastic half-space is assumed to be smooth and fully permeable. Kirchhoff small-deflection thin-plate theory is employed to analyze the plate, while Biot’s fully dynamic poroelastic theory is used to characterize the poroelastic half-space. The frequency wave-number domain solution of the pavement system is obtained by the compatibility condition between the plate and the poroelastic half-space. By applying the inverse fast Fourier transform, the time domain solution is obtained. Also, the influences of the load speed, the permeability of the soil, and the flexural rigidity of the plate on the response of the pavement system are investigated. The numerical results show that the influences of these parameters on the dynamic response of the pavement system are significant.     

Darcys Law Expressed by Chemical Index

Ｉｎ 18 5 6 ,ＨｅｎｒｙＤａｒｃｙｐｕｂｌｉｓｈｅｄｈｉｓｌａｗ ,ｔｈｅＤａｒｃｙ’ｓｌａｗ ,ｅｘｐｒｅｓｓｅｄｂｙｈｙｄｒａｕｌｉｃｉｎｄｅｘｔｈｒｏｕｇｈａｌｏｎｇ ｔｅｒｍｅｘｐｅｒｉｍｅｎｔｏｆｗａｔｅｒｐｅｒｍｅａｔｉｏｎｉｎｍｕｌｔｉ ｍｉｎｅｒａｌｍｅｄｉｕｍ (Ｘｕ ,1986 ) ,ｗｈｉｃｈｎｏｔｏｎｌｙｍｅｔｔｈｅｕｒｇｅｎｔｎｅｅｄｏｆｔｈｅｄｅｖｅｌｏｐｍｅｎｔｏｆｓｏｃｉａｌｅｃｏｎｏ ｍｙａｎｄｐｒａｃｔｉｃｅｆｏｒｃａｌｃｕｌａｔｉｏｎｏｆｗｅｌｌｗａｔｅｒｑｕａｎｔｉｔｙａｔｔ…     

Evolution mechanism of the western Pacific subtropical high

Ever since Charney et al.[1] studied the multiple equilibrium states in atmosphere with highly truncated spectral method in 1979, many Chinese researchers, such as Li Maicun et al. (1983)[2], Liu Chongjian et al. (1983)[3], Miu Jinhai et al. (1985)[4] and…     

生物气CO2还原途径中碳同位素分馏作用研究及应用

地质历史中,CO2/H2还原产甲烷作用对生物气的形成具有十分重要的意义。中国柴达木盆地第四系生物气主要为CO2/H2还原型生物气。笔者以CO2/H2还原生气理论为指导,进行不同初始碳同位素值和不同赋存状态碳源的生物模拟实验,研究CO2/H2还原产气过程中发生的碳同位素分馏作用。实验结果表明,产物中δ13CH4值与底物的δ13C值呈很好的正相关关系;在反应母质过量的情况下,碳源的赋存状态可以影响产物甲烷的碳同位素组成。以游离形式CO2还原产生的甲烷δ13C值,相对于以HCO3-、CO23-离子形式产生的甲烷δ13C值轻。通过柴达木盆地东部第四系生物气田实例分析,探讨了该区生物气的主要底物CO2的来源及赋存状态,对评价盆地生物气资源和有利勘探区预测有重要的参考价值。     

Theory of relativity and super-luminal speeds

It is possible that the Finsler space-timeF( _{x, y} ) may be endowed with a catastrophic nature. In particular, the horizon of the field of the general relativity is just a catastrophic set. If so, a particle with the super-luminal speeds could be projected near the horizon of these fields, and the particle will move on the space-like curves. It is very interesting that, in the Schwarzschild fields, the theoretical calculation as the space-like curves should be in agreement with the data of the superluminal expansion of extragalactic radio sources observed year after year.The project has been supported by the National Natural Science Foundation of China.