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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 {2. national Astronomical observatories, 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

Planet Host Stars: Mass, Age and Kinematics

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chinese Journal of Astronomy and Astrophysics 2002年第2期2卷 151-160页

作者： Yu-Qin Chen and gang zhao {2. Astronomical observatories, chinese academy of sciences, beijing 100012 national Astronomical observatories Chinese Academy of Sciences Beijing 100012

We determine the mass, age and kinematics of 51 extra-solar planet host stars. The results are then used to search for signs of connection of the data with metallicity and to investigate the population nature. We find that the increase in mean metallicity with stellar mass is similar to that in normal field stars, so it seems unsuitable to use this relation as a constraint on the theory of planet formation. The age and kinematic distributions seem to favour the metallicity of extra-solar planet host stars being initial. Although the kinematic data of these stars indicate their origin from two populations - the thin and the thick disks, kinematics may not help in the maintenance of the planet around the host. Stars with planets, brown dwarfs or stellar companions are sorted into three groups and re-investigated separately for their formation mechanism. The main results indicate that stars with M2.2.M3 have [Fe/H] > 0.1 and a wide period range, but there are no other differences. Thus, there does not seem to be any physically distinguishable characteristics among the three star groups.

关键词： stars: masses ages ─ stars: kinematics -planetary system

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 {2. Astronomical 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

Equivalent Widths of 15 Extrasolar-Planet Host Stars

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chinese Journal of Astronomy and Astrophysics 2002年第4期2卷 377-390页

作者： gang zhao, Yu-Qin Chen and {2.-Mei Qiunational Astronomical observatories, chinese academy of sciences, beijing 100012 national Astronomical observatories CAS NAOC Beijing 100012 China

We present the equivalent widths of 15 extrasolar-planet host stars. These data were based on the high-resolution, high signal-to-noise ratio spectra obtained with the 2.16m telescope at Xinglong station. The error in the Xinglong equivalent width is estimated by a comparison of these data with those given in previous studies of common stars.

关键词： stars: planetary systems - stars: late-type

Information from the Kinematics of F and G Stars in the Solar Neighborhood

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chinese Journal of Astronomy and Astrophysics 2002年第5期2卷 419-428页

作者： Yu-Qin Chen, gang zhao and Jian-Rong Shi{2. Astronomical observatories, chinese academy of sciences, beijing 100012 national Astronomical observatories Chinese Academy of Sciences Beijing 100012

We have calculated the orbital parameters for 90 stars in Chen et al. and updated the kinematic data for stars in Edvardsson et al. by using the accurate Hipparcos parallaxes and proper motions, and recalculated the α-element abundances in Edvardsson et al. in a way consistent with Chen et al. The two sets of data are combined in a study of stellar populations and characteristics of F & G stars in the solar neighborhood. We confirm the result of Chen et al. that a distinguishable group of stars may belong to the thick disk rather than the thin disk. The ages for the stars are determined using the theoretical isochrones of VandenBerg et al. The age-metallicity relation is investigated for different subgroups according to distance from the sun and galactic orbital parameters. It is found that a mixing of stars with different orbital parameters significantly affect the age-metallicity relation for the disk. Stars with orbits confined to the solar circle all have metallicities [Fe/H] > -0.3 irrespective of their distances from the sun or from the Galactic plane.

关键词： stars: kinematics - Galaxy: evolution - Galaxy: solar neighborhood

New Hybrid CHP System Integrating Solar Energy and Exhaust Heat Thermochemical Synergistic Conversion with Dual-Source Energy Storage

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Journal of Thermal Science 2024年第3期33卷 970-984页

作者： QIN Yuanlong liU Taixiu li Peijing {2. Kai JIAO Fan PEI gang liU Qibin Department of Thermal Science and Energy Engineering University of Science and Technology of ChinaHefei230027China Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing100190China University of chinese academy of sciences Beijing100049China School of Energy Power and Mechanical EngineeringNorth China Electric Power UniversityBeijing102206China

For the efficient use of solar and fuels and to improve the supply-demand matching performance in combined heat and power(CHP)systems,this paper proposes a hybrid solar/methanol energy system integrating solar/exhaust thermochemical and thermal energy *** proposed system includes parabolic trough solar collectors(PTSC),a thermochemical reactor,an internal combustion engine(ICE),and hybrid storage of thermal and chemical energy,which uses solar energy and methanol fuel as input and outputs power and *** methanol thermochemical decomposition reaction,mid-and-low temperature solar heat and exhaust heat are upgraded to chemical energy for efficient power *** thermal energy storage(TES)stores surplus thermal energy,acting as a backup source to produce heat without emitting CO_(2..Due to the energy storage,time-varying solar energy can be used steadily and efficiently;considerable supply-demand mismatches can be avoided,and the operational flexibility is *** the design condition,the overall energy efficiency,exergy efficiency,and net solar-to-electric efficiency achieve 72.09%,37.65%,and 2..63%,*** fuel saving rate(FSR)and the CO_(2. emission reduction(ER_(CO_(2.))achieve 32.97%and 2..33%,*** research findings provide a promising approach for the efficient and flexible use of solar energy and fuels for combined heat and power.

关键词： hybrid energy system solar thermochemical exhaust heat energy storage operational flexibility

Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope

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Research in Astronomy and Astrophysics 2011年第11期11卷 1298-1310页

作者： Zhou Fan1,2.Ya-Fang Huang1,2.Jin-Zeng li1,2.Xu Zhou1,2.Jun Ma1,2.hong Wu1,2.Tian-Meng Zhang1,2.and Yong-Heng {2.1,2.1 national Astronomical observatories,chinese academy of sciences,beijing 100012,China 2.Key Laboratory of Optical Astronomy,national Astronomical observatories,chinese academy of sciences,beijing 100012,China national Astronomical observatories Chinese Academy of Sciences Beijing 100012 China Key Laboratory of Optical Astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We present spectroscopic observations for 11 confirmed globular clusters(GCs) of M31 with the OMR spectrograph on the 2.16 m telescope at the Xinglong site of national Astronomical observatories,{2. academy of *** of our sample clusters are located in the halo of M31 and the most remote one is out to a projected radius of 78.75 kpc from the galactic *** all our sample clusters,we measured the lick absorption-line indices and radial *** is noted that most GCs in our sample are distinct from the HI rotation curve of galaxy M31,especially for B514,MCGC5,H12.and B517,suggesting that most of our sample clusters do not have a kinematic association with the star-forming young disk of the *** separately fitted the absorption line indices from the updated stellar population model of Thomas et *** two different tracks of Cassisi and Padova,by applying the χ2.minimization *** fitting results show that all our sample clusters are older than 10 Gyr,and metal-poor(2.38 ≤ [Fe/H] ≤ 0.91 dex).After merging the spectroscopic metallicity of our work with the previously published ones,we extended the cluster sample out to a projected radius of 117 kpc from the galaxy's *** found the metallicity gradient exists for all the confirmed clusters with a slope of 0.02. ± 0.001 dex kpc ***,the slope turns out to be 0.018 ± 0.001 dex kpc 1 for all the halo clusters,which is much *** we only consider the outer halo clusters with rp > 2. kpc,the slope becomes 0.010 ± 0.002.dex kpc 1 and if one cluster G001 is excluded from the outer halo sample,the slope is 0.004 ± 0.002.dex kpc ***,we conclude that the metallicity gradient for M31's outer halo clusters is not significant,which agrees well with previous findings.

关键词： galaxies individual(M31) — galaxies star clusters — globular clusters general — star clusters general

Source apportionment and suitability evaluation of seasonal VOCs contaminants in the soil around a typical refining-chemical integration park in China

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Journal of Environmental sciences 2024年第3期137卷 651-663页

作者： Xu zhao Jing Meng Qianqian li Guijin Su Qifan Zhang {2. Shi lingwen Dai Yong Yu Key Laboratory of Environmental Nanotechnology and Health Effects State Key Laboratory of Environmental Chemistry and EcotoxicologyResearch Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of chinese academy of sciences Beijing 100049China State Environmental Protection Key Laboratory of Quality Control in Environmental Monitoring China National Environmental Monitoring CenterBeijing 100012China

Accurate source apportionment of volatile organic compounds(VOCs)in soil nearby petrochemical industries prevailing globally,is critical for preventing ***,in the process,seasonal effect on contamination pathways and accumulation of soil VOCs is often ***,Yanshan Refining-Chemical Integration Park,including a carpet,refining,synthetic rubber,and two synthetic resin zones,was selected for *** variations resulted in a gradual decrease of 31 VOCs in soil from winter to summer.A method of dry deposition resistance model coupling partitioning coefficient model was created,revealing that dry deposition by gas phase was the primary pathway for VOCs to enter soil in winter and spring,with 100 times higher fux than by particle *** profiles for five zones were built by gas sampling with distinct substance indicators screened,which were used for positive matrix factorization factors *** of the five zones were 14.9%,2..8%,13.6%,2..1%,and 2..6%in winter and 33.4%,12.5%,10.7%,2..9%,and 18.5%in spring,*** variation in the soil sorption capacity of VOCs causes inter-seasonal differences in *** better correlation between dry deposition capacity and soil storage of VOCs made root mean square and mean absolute errors decrease averagely by 8.8%and 5.5%in winter compared to *** study provides new perspectives and methods for the source apportionment of soil VOCs contamination in industrial sites.

关键词： Dry deposition resistance model Positive matrix factorization model Partitioning coefficient model Contamination pathway Source profile

What benefit can be obtained from magnetic resonance imaging diagnosis with artificial intelligence in prostate cancer compared with clinical assessments?

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Military Medical Research 2024年第2期11卷 268-286页

作者： li-Tao zhao Zhen-Yu liu Wan-Fang Xie li-Zhi Shao Jian Lu Jie Tian Jian-gang liu School of Engineering Medicine Beihang UniversityBeijing 100191China School of Biological Science and Medical Engineering Beihang UniversityBeijing 100191China CAS Key Laboratory of Molecular Imaging Institute of AutomationBeijing 100190China University of chinese academy of sciences Beijing 100080China Department of Urology Peking University Third HospitalPeking UniversityBeijing 100191China Key Laboratory of Big Data‑Based Precision Medicine(Beihang University) Ministry of Industry and Information Technology of the People's Republic of ChinaBeijing 100191China beijing Engineering Research Center of Cardiovascular Wisdom Diagnosis and Treatment Beijing 100029China

The present study aimed to explore the potential of artificial intelligence(AI)methodology based on magnetic resonance(MR)images to aid in the management of prostate cancer(PCa).To this end,we reviewed and summarized the studies comparing the diagnostic and predictive performance for PCa between AI and common clinical assessment methods based on MR images and/or clinical characteristics,thereby investigating whether AI methods are generally superior to common clinical assessment methods for the diagnosis and prediction fields of ***,we found that,in the included studies of the present study,AI methods were generally equal to or better than the clinical assessment methods for the risk assessment of PCa,such as risk stratification of prostate lesions and the prediction of therapeutic outcomes or PCa *** particular,for the diagnosis of clinically significant PCa,the AI methods achieved a higher summary receiver operator characteristic curve(SROC-AUC)than that of the clinical assessment methods(0.87 vs.0.82..For the prediction of adverse pathology,the AI methods also achieved a higher SROC-AUC than that of the clinical assessment methods(0.86 vs.0.75).Second,as revealed by the radiomics quality score(RQS),the studies included in the present study presented a relatively high total average RQS of 15.2.11.0–2..0).Further,the scores of the individual RQS elements implied that the AI models in these studies were constructed with relatively perfect and standard radiomics processes,but the exact generalizability and clinical practicality of the AI models should be further validated using higher levels of evidence,such as prospective studies and open-testing datasets.

关键词： Clinically significant prostate cancer Adverse pathology Radiomics quality score Artificial intelligence Magnetic resonance imaging