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Modeling earthquake indexes derived from the earthquake warning system upon the planet earth

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Science china(Physics,Mechanics & Astronomy) 2010年第12期53卷 2293-2299页

作者： li yong National {2. observatories, chinese academy of sciences, beijing 100012, china 1. National astronomical observatories Chinese Academy of Sciences Beijing 100012 China

By studying the correlation between historical earthquake data and the distributional characteristics of parameters of solid earth tides in the earthquake epicenter, we are able to design a forecasting function of earthquake probability. We put forward a design method for the Earthquake Warning System. The model could theoretically simulate and be used to predict the probability of strong earthquakes that could occur anywhere at any time. In addition, the system could also conveniently obtain global or partial Modeling Earthquake Indexes to finally combine the precise pointing prediction and forecast of partial indexes. The literature quotes global data values, provided by NEIC, of 1544 M ≥ 6.5 earthquakes. It also gives examples of instantaneous earthquake indexes of the whole world and Taiwan Region on 1st January 2.10, UT=0:00 and the average earthquake index near the Taiwan Region. According to the 10-year pointing prediction of strong earthquakes in San Francisco, the literature provides the average earthquake index on 2.th June 2.15 (± 15 days), in its neighborhood.

关键词： earthquake earthquake warning system astrogeodynamics index

Steps Towards a Fully Automated Classification and Redshiftmeasurement Pipeline for LAMOST Spectra. I. Continuum level and wavelength estimation for galaxies

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chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 563-572页

作者： A-li Luo and yong-Heng Zhao National {2. observatories, chinese academy of sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

The Large Sky-Area Multi-Object Spectroscopic Telescope (LAMOST) under construction by the National astronomical observatories will yield up to four thousand multi-fiber spectra of stars and galaxies per field. The present series of papers describes the automated data-reduction pipe{2.ne currently being designed in order to cope with the anticipated flood of spectrographic data. In this pre{2.minary paper, we present an automated method for estimating the continuum level, the positions of strong {2.nes and the 4000 A break in galaxy spectra. In order to obtain detailed information on the continuum, we use a wavelet filter bank. After continuum fitting, our software searches for a 4000 A break and distinguishes between emission-{2.ne galaxies (ELGs) and non-ELGs according to whether the break is small or large. It then searches for strong {2.nes and measures the intensities of emission {2.nes and the equivalent widths of absorption {2.nes. For non-ELGs, the absorption {2.nes are identified automatically yielding redshift measurements.

关键词： methods: data analysis - techniques: spectroscopic - galaxies: emission lines - galaxies: absorption lines

A network flow algorithm to position tiles for LAMOST

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Research in Astronomy and Astrophysics 2009年第11期9卷 1277-1284页

作者： Guang-Wei li and Gang Zhao National astronomical {2., chinese academy of sciences, beijing 100012, china National astronomical observatories Chinese Academy of Sciences Beijing 100012 China

We introduce the network flow algorithm used by the Sloan Digital Sky Survey （SDSS） into the sky survey of the Large sky Area Multi-Object fiber Spectroscopic Telescope （LAMOST） to position tiles. Because fibers in LAMOST＇s focal plane are distributed uniformly, we cannot use SDSS＇ method directly. To solve this problem, firstly we divide the sky into many small blocks, and we also assume that all the targets that are in the same block have the same position, which is the center of the block. Secondly, we give a value to limit the number of the targets that the LAMOST focal plane can collect in one square degree so that it cannot collect too many targets in one small block. Thirdly, because the network flow algorithm used in this paper is a bipartite network, we do not use the general solution algorithm that was used by SDSS. Instead, we give our new faster solution method for this special network. Compared with the Convergent Mean Shift Algorithm, the network flow algorithm can decrease observation times with improved mean imaging quality. This algorithm also has a very fast running speed. It can distribute millions of targets in a few minutes using a common personal computer.

关键词： methods data analysis -- methods statistical

Thermal analysis of the baffle structure of the Solar Space Telescope

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1755-1764页

作者： li Rong1,2.3 & WANG Sen1,3 1 National astronomical {2.,chinese academy of sciences,beijing 100012,china 2.Graduate University of chinese academy of sciences,beijing 100049,china 3 Key Laboratory of Solar Activity,National astronomical {2. of chinese academy of sciences,beijing 100012,china 1. National astronomical observatories Chinese Academy of Sciences Beijing 100012 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Key Laboratory of Solar Activity National Astronomical Observatories of Chinese Academy of Sciences Beijing 100012 China

The SST(Space Solar Telescope) is an astronomical telescope with a primary mirror of 1 m in *** observes the sun with a small view field to ensure that its high spatial resolution imaging has 0.1″-0.15″ and high SNR(signal to noise ratio).Surrounding the small view field is still the sun,which is an intense source of both heat and stray *** baffles(the main baffle,the aperture,and the outer baffle),which are used to eliminate the stray light,will change the thermal flux in the SST and will weaken the effect of the thermal control *** this study,the compatibility analysis of the thermal effect of baffle structures in SST is *** GCF(Geometry Composing Function) and BRDF(Bidirectional Reflectance Distribution Function),which are two inherent related parameters in the compatibility analysis,are *** objective and method of the compatibility analysis are *** the thermal analysis software,the temperature fields are calculated for different lengths of the main baffle,different radii of apertures,different lengths of the outer baffle with a 3' tilt angle and 16' tilt angle,and different tilt angles of the outer baffle with a 2.0 mm length.A series of configurations and sizes of the baffles are studied with the goals of both thermal control and elimination of stray *** design of the baffle structure of SST is achieved:the main baffle of length 4100 mm,the internal shield of radius 494 mm,the outer baffle of length 2.0 mm,and the outer baffle of tilt angle 3' are successfully *** paper presents the relationship between the thermal control design and stray light elimination plan in the *** aims of the optimal design of the baffle structure of SST are *** thoughts and methods of the optimal analysis are also useful for similar optical telescopes designed for solar observation.

关键词： baffle the main baffle the outer baffle GCF BRDF

Observational Accuracy of Sunrise and Sunset Times in the Sixth Century china

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chinese Journal of Astronomy and Astrophysics 2006年第5期6卷 629-634页

作者： yong li National astronomical observatories Chinese Academy of Sciences Beijing 100012

The Daye Calendar was compiled in AD 597 in the Sui Dynasty. We investigate the records of sunrise and sunset times on the 2. solar-term days in the calendar. By converting the ancient chinese time units, Chen, Ke and Fen to hour, minute and second, and carrying out a comparison between the ancient records and values computed with modem astronomical theory, we find that the accuracy of solar measurements in the Sui period is remarkably high： for sunrise times, the average absolute deviation is 3.63 min （this value can be further reduced to 3.03 min when erroneous data are excluded）, and for sunset times it is 3.48 min. We also find that the observed sunrise and sunset times are strictly symmetrically distributed with respect to both the Winter Solstice and the Summer Solstice, with their deviations showing a similar symmetrical distribution as well. We give a discussion on the date of observation, the feature of the data, and possible reasons of the deviation.

关键词： history of astronomy -- astrometry -- solar-terrestrial relations -- methods statistical

Learning Vector Quantization for Classifying astronomical Objects

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chinese Journal of Astronomy and Astrophysics 2003年第2期3卷 183-190页

作者： Yan-Xia Zhang and yong-Heng ZhaoNational astronomical {2., chinese academy of sciences, beijing 100012 National astronomical observatories CAS NAOC Beijing 100012 China

The sizes of astronomical surveys in different wavebands are increasing rapidly. Therefore, automatic classification of objects is becoming ever more important. We explore the performance of learning vector quantization (LVQ) in classifying multi-wavelength data. Our analysis concentrates on separating active sources from non-active ones. Different classes of X-ray emitters populate distinct regions of a multidimensional parameter space. In order to explore the distribution of various objects in a multidimensional parameter space, we positionally cross-correlate the data of quasars, BL Lacs, active galaxies, stars and normal galaxies in the optical, X-ray and infrared bands. We then apply LVQ to classify them with the obtained data. Our results show that LVQ is an effective method for separating AGNs from stars and normal galaxies with multi-wavelength data.

关键词： method: data analysis - method: statistical - catalogs

What does the Sun tell and hint now?

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Research in Astronomy and Astrophysics 2009年第9期9卷 959-965页

作者： Ke-Jun li1,2.1 National astronomical {2. /Yunnan Observatory,chinese academy of sciences,Kunming 650011,china 2.Key Laboratory of Solar Activity,National astronomical {2.,chinese academy of sciences,{12. 100012,china National astronomical observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory of Solar Activity National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

Some historical records, which have held since the beginning of modern solar activity cycles, are being broken by the present Sun： cycle 2. records the longest cycle length and fall time; latitudes of high-latitude sunspots belonging to a new cycle around the minimum time of the cycle are statistically the lowest at present, compared with those of other cycles; there are only one or no sunspots in a month appearing at high latitudes for 58 months, which is the first time that such a long duration has been observed. The solar dynamo is believed to be slowing down due to：（1） the minimum smoothed monthly mean sunspot number is the smallest since cycle 16 onwards, and even probably among all modern solar cycles; and （2. once the time interval between the first observations of two neighboring sunspot groups is larger than 14 d, it should be approximately regarded as an observation of no sunspots on the visible solar disk, called a spotless event. Spotless events occur with the highest frequency around the minimum time of cycle 2., and the longest spotless event also appears around the minimum time for observations of the Sun since cycle 16. Cycle 2. is expected to have the lowest level of sunspot activity from cycle 16 onwards and even probably for all of the modern solar cycles.

关键词： Sun: activity -- Sun: general -- sunspots

Gamma-ray Bursts: a Probe of Black Holes

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chinese Journal of Astronomy and Astrophysics 2001年第6期1卷 487-493页

作者： Wei Wang and yong-Heng Zhao National astronomical {2., chinese academy of sciences, beijing 100012 National astronomical observatories Chinese Academy of Sciences Beijing 100012

There is strong evidence for the existence of black holes (BHs) in some X-ray binaries and in most galactic nuclei based on different types of measurement, but black holes have not been definitely identified for the lack of very firm observational evidence up to now. Because direct evidence for BHs should come from determination of strong gravitational redshift, we expect an object can fall into the region near the BH horizon where radiation can be detected. Therefore the object must be a compact star such as a neutron star (NS), and intense astrophysical processes will release highly energetic radiation that is transient and fast-varying. These characteristics may point to the observed gamma-ray bursts (GRBs). Recent observations of iron lines suggest that afterglows of GRBs show properties similar to those observed in active galactic nuclei (AGNs), implying that the GRBs may originate from intense events related to black holes. A model for GRBs and after-glows is proposed here to obtain the range of gravitational redshifts (zg) of GRBs with known cosmological redshifts. Here, we provide a new method that, with a search for high-energy emission lines (X- or -γ-rays) in GRBs, one can determine the gravitational redshift. We expect zg to be 0.5 or even larger, so we can rule out the possibility of other compact objects such as NSs, and identify the central progenitors of GRBs as black holes.

关键词： black hole physics - accretion accretion disks - gamma rays: burst

Projection Effects on Physical Parameters Obtained from Solar Vector Magnetograms

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chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 174-182页

作者： Hui li Purple Mountain Observatory, chinese academy of sciences, Nanjing 2.0008 National {2. observatories, chinese academy of sciences, beijing 100012 Purple Mountain Observatory Chinese Academy of Sciences Nanjing 210008 []National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Projection effects in Huairou solar vector magnetograms are corrected by transferring or mapping the observed vector magnetogram in the image plane to the heliographic plane (planar correction) and to the heliospheric coordinate system (spherical correction). The magnetograms after the correction are considerably dif- ferent. The planar correction and the spherical correction lead to slightly different magnetic configurations, especially when the active region involved is far from the disk center. We also discuss the effects of the corrections on magnetic activity pa- rameters, such as magnetic shear, current helicity, etc. It is shown that the neutral line is obviously distorted after the mapping. The mapping generally decreases the average shear angle on the neutral line by several degrees when the active region is in the eastern hemisphere, and increases it when in the western hemisphere. In most of the cases studied, the correction reduces the current helicity imbalance, and sometimes even changes its sign. It is found that the current helicity imbalance may change its sign in its evolution when there are apparent fluxes emerging from the lower photosphere. The corrections increase the noise level of Bz greatly, and decrease the noise level of B~ slightly. The accuracy of the magnetic field measure- ment at Huairou is estimated to be better than 2. G and 150 G for the longitudinal and the transverse component, respectively.

关键词： Sun: magnetic fields ─Sun: activity ─Sun: photosphere