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An open-loop control algorithm of the active reflector system of FAST

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Research in Astronomy and Astrophysics 2020年第5期20卷 93-102页

作者： Hui Li Peng Jiang National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

An open-loop control algorithm is put forward for continuous paraboloid deformation of the active reflector system of the Five-hundred-meter Aperture Spherical radio Telescope(FAST).The method is based on a calibration database and interpolation in 2D spatial domain and temperature domain,*** is completely independent of real-time measurement of cable nodes so that it has advantage of working all-weather and no additional electro-magnetic interference(EMI).Furthermore,its control accuracy can be effectively improved via reasonable layout of the calibrated paraboloids and increasing calibration *** deformation safety is considered via calibration as *** its control accuracy is also confirmed via site measurements of paraboloid deformations.

关键词： Astronomical instrumentation:methods and techniques methods:data analysis methods:numerical

Radio frequency compatibility analysis for BDSBAS and GPS/WAAS

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Research in Astronomy and Astrophysics 2021年第8期21卷 235-244页

作者： Cheng Liu Wei-Guang Gao Jun Lu Yi Zhou Shan-Shan Chen Beijing institute of Tracking and Telecommunication Technology Beijing 100094China BeiDou Application Research Academy of Norinco Group Beijing 100089China Space Star Technology Beijing 100094China

Radio frequency signal compatibility is the basis of interoperability of the Satellite eBased Augmentation System(SBAS).SBAS should abide by relative international radio regulations of International Telecommunication Union(ITU) and meet the compatibility requirements of radio frequency signal between the Global Navigation Satellite System(GNSS)/SBAS,in order to avoid negative mutual *** to ITU Proposal and related reference and assumptions,the paper made simulation of signal receiving maximum power in the Bei Dou Satellite-Based Augmentation System(BDSBAS)global signal *** then,interference of BDSBAS to Global Positioning System(GPS)/WAAS(Wide Area Augmentation System) on L1/L5 bands were calculated and analyzed,with equivalent carrierto-noise ratio as the evaluation *** result shows that the carrier-to-noise ratio decrease of GPS/WAAS caused by BDSBAS B1 C and B2 a signals are extremely lower than inter-system interference of GPS/WAAS,and thus can be ignored in practical ***,BDSBAS will not cause the service performance degradation of GPS and WAAS.

关键词： space vehicles methods:data analysis celestial mechanics

A novel hybrid algorithm for lucky imaging

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Research in Astronomy and Astrophysics 2021年第5期21卷 155-167页

作者： Jin-Liang Wang Bin-Hua Li Xi-Liang Zhang Faculty of information engineering and automation Kunming University of Science and TechnologyKunming 650500China Key Laboratory of Applications of Computer Technologies of the Yunnan Province Kunming University of Science and TechnologyKunming 650500China Yunnan Observatories Chinese Academy of SciencesKunming 650011China

Lucky imaging is a high-resolution astronomical image recovery technique with two classic implementation algorithms,*** selecting,shifting and adding in image space,and data selecting and image synthesizing in Fourier *** paper proposes a novel lucky imaging algorithm where with space-domain and frequency-domain selection rates as a link,the two classic algorithms are combined successfully,making each algorithm a proper subset of the novel hybrid *** results show that with the same experiment dataset and platform,the high-resolution image obtained by the proposed algorithm is superior to that obtained by the two classic *** paper also proposes a new lucky image selection and storage scheme,which can greatly save computer memory and enable lucky imaging algorithm to be implemented in a common desktop or laptop with small memory and to process astronomical images with more frames and larger *** addition,through simulation analysis,this paper discusses the binary star detection limits of the novel lucky imaging algorithm and traditional ones under different atmospheric conditions.

关键词： methods:data analysis techniques:high angular resolution techniques:image processing

Solar radio filtering algorithm based on improved long short-term memory

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Research in Astronomy and Astrophysics 2021年第4期21卷 79-92页

作者： Qing-Fu Du Qiao-Man Zhang Xin Li Chang-Lin Gao School of Mechanical Electrical&Information EngineeringShandong UniversityWeihai 264209China

The effective observation of burst events in solar radio research has been impeded by various interference signals,especially interference signals with a wide frequency range and high intensity,as they can partially or completely obscure the observation of burst *** processing methods that directly remove the interference signal channels and subtract the average of the interference signal channel are not suitable for processing all types of interference *** paper proposes the use of a specific kind of recurrent neural networks,called long short-term memory networks,to predict the value of the radio frequency interference signals with high intensity of the burst event in the solar radio *** predicted interference can then be removed in accordance with the principle that signals can be linearly ***,predicted value is subtracted from the data containing the burst event signals and the RFI signals(The radio frequency interference signals to be processed in this article refer to the signal of the broadcast signal that can be received in the frequency range,the signal transmitted by the mobile phone,and the signal transmitted by the sea vessel,and the like)to remove the ***,in order to reduce the error caused by the stepwise prediction in the network and further improve the prediction accuracy,this paper analyzes the characteristics of the value of the radio interference and applies the digital mapping method to convert the prediction problem into the classification problem in the time *** experimental results show that the proposed method can effectively remove the radio interference in the solar spectrum and clearly show the burst events.

关键词： Sun:radio radiation methods:data analysis techniques:image processing

Mapping of Compositional Diversity and Chronological Ages of Lunar Farside Multiring Mare Moscoviense Basin:Implications to the Middle Imbrian Mare Basalts

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Research in Astronomy and Astrophysics 2022年第12期22卷 130-151页

作者： A.Karthi S.Arivazhagan Manish Sharma Centre for Applied Geology The Gandhigram Rural Institute—Deemed to be UniversityGandhigramDindigul-624302Tamil NaduIndia College of Natural and Health Sciences Zayed UniversityP.O.Box 144534Abu DhabiUnited Arab Emirates

The Mare Moscoviense is an astonishing rare flatland multi-ring basin and one of the recognizable mare regions on the Moon's *** mineralogical,chronological,topographical and morphological studies of the maria surface of the Moon provide a primary understanding of the origin and evolution of the mare *** this study,the Chandrayaan-1 M^(3)data have been employed to prepare optical maturity index,FeO and TiO^(2)concentration,and standard band ratio map to detect the mafic indexes like olivine and pyroxene *** crater size frequency distribution method has been applied to LROC WAC data to obtain the absolute model ages of the Moscoviense *** four geological unit ages were observed as 3.57 Ga(U-2),3.65 Ga(U-1),3.8 Ga(U-3)and 3.92 Ga(U-4),which could have been formed between the Imbrian and Nectarian *** M^(3)imaging and reflectance spectral parameters were used to reveal the minerals like pyroxene,olivine,ilmenite,plagioclase,orthopyroxene-olivine-spinel lithology,and olivine-pyroxene mixtures present in the gabbroic basalt,anorthositic and massive ilmenite rocks,and validated with the existing *** results show that the Moscoviense basin is dominated by intermediate TiO^(2)basalts that derived from olivine-ilmenite-pyroxene cumulate depths ranging from 200 to 500 km between 3.5 Ga and 3.6 Ga.

关键词： astrobiology molecular processes methods:data analysis techniques:image processing techniques:imaging spectroscopy techniques:spectroscopic planets and satellites:composition planets and satellites:surfaces planets and satellites:terrestrial planets

Stellar loci *** giant stars

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Research in Astronomy and Astrophysics 2021年第12期21卷 550-562页

作者： Ruo-Yi Zhang Hai-Bo Yuan Xiao-Wei Liu Mao-Sheng Xiang Yang Huang Bing-Qiu Chen Department of Astronomy Beijing Normal UniversityBeijing 100875China South-Western Institute for Astronomy Research Yunnan UniversityKunming 650500China Max-Planck Institute for Astronomy KonigstuhlD-69117HeidelbergGermany

In the fourth paper of this series,we present the metallicity-dependent Sloan Digital Sky Survey(SDSS)stellar color loci of red giant stars,using a spectroscopic sample of red giants in the SDSS Stripe82 *** stars span a range of 0.55-1.2 mag in color g-i,-0.3--2.5 in metallicity[Fe/H],and have values of surface gravity log g smaller than 3.5 *** in the case of main-sequence(MS)stars,the intrinsic widths of loci of red giants are also found to be quite narrow,a few mmag at *** are however systematic differences between the metallicity-dependent stellar loci of red giants and MS *** colors of red giants are less sensitive to metallicity than those of MS *** good photometry,photometric metallicities of red giants can be reliably determined by fitting the u-g,g-r,r-i,and i-z colors simultaneously to an accuracy of 0.2-0.25 dex,comparable to the precision achievable with low-resolution spectroscopy for a signal-to-noise ratio of *** comparing fitting results to the stellar loci of red giants and MS stars,we propose a new technique to discriminate between red giants and MS stars based on the SDSS *** technique achieves completeness of~70 per cent and efficiency of~80 per cent in selecting metal-poor red giant stars of[Fe/H]≤-*** thus provides an important tool to probe the structure and assemblage history of the Galactic halo using red giant stars.

关键词： methods:data analysis stars:fundamental parameters stars:general surveys

Fine-grained distributed averaging for large-scale radio interferometric measurement sets

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Research in Astronomy and Astrophysics 2021年第4期21卷 93-100页

作者： Shou-Lin Wei Kai-Da Luo Feng Wang Hui Deng Ying Mei Faculty of Information Engineering and Automation Computer Technology Application Key Lab of Yunnan ProvinceKunming University of Science and TechnologyKunming 650500China Center for Astrophysics Guangzhou UniversityGuangzhou 510006China

The Square Kilometre Array(SKA)would be the world’s largest radio telescope with eventually over a square kilometre of collecting ***,there are enormous challenges in its data *** use of modern distributed computing techniques to solve the problem of massive data processing in the SKA is one of the most important *** this study,basing on the Dask distribution computational framework,and taking the visibility function integral processing as an example,we adopt a multi-level parallelism method to implement distributed averaging over time and *** Array was used to implement super large matrix or arrays with supported *** maximize the usage of memory,we further exploit the data parallelism provided by Dask that intelligently distributes the computational load across a network of computer agents and has a built-in fault tolerance *** validity of the proposed pattern was also verified by using the Common Astronomy Software Application(CASA),wherein we analyze the smearing effects on images reconstructed from different resolution visibilities.

关键词： techniques:interferometric methods:data analysis methods:numerical instrumentation:interferometers

The influence of the Insight-HXMT/LE time response on timing analysis

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Research in Astronomy and Astrophysics 2021年第1期21卷 45-52页

作者： Deng-Ke Zhou Shi-Jie Zheng Li-Ming Song Yong Chen Cheng-Kui Li Xiao-Bo Li Tian-Xiang Chen Wei-Wei Cui Wei Chen Da-Wei Han Wei Hu Jia Huo Rui-Can Ma Mao-Shun Li Tian-Ming Li Wei Li He-Xin Liu Bo Lu Fang-Jun Lu Jin-Lu Qu You-Li Tuo Juan Wang Yu-Sa Wang Bai-Yang Wu Guang-Cheng Xiao Yu-Peng Xu Yan-Ji Yang Shu Zhang Zi-Liang Zhang Xiao-Fan Zhao Yu-Xuan Zhu Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China College of Physics Jilin UniversityChangchun 130012China

The LE is the low energy telescope that is carried on *** uses swept charge devices(SCDs)to detect soft X-ray ***’s time response is caused by the structure of the *** theoretical analysis and Monte Carlo simulations we discuss the influence of LE time response(LTR)on the timing analysis from three aspects:the power spectral density,the pulse profile and the time *** the LTR,the value of power spectral density monotonously decreases with the increasing *** power spectral density of a sinusoidal signal reduces by a half at frequency 536 *** corresponding frequency for quasi-periodic oscillation(QPO)signals is 458 *** root mean square(RMS)of QPOs holds a similar *** the LTR,the centroid frequency and full width at half maxima(FWHM)of QPOs signals do not *** LTR reduces the RMS of pulse profiles and shifts the pulse *** the time domain,the LTR only reduces the peak value of the cross-correlation function while it does not change the peak position;thus it will not affect the result of the time *** considering the time lag obtained from two instruments and one among them is LE,a 1.18 ms lag is expected caused by the *** time lag calculated in the frequency domain is the same as that in the time domain.

关键词： instrumentation:detectors methods:data analysis methods:analytical

Prognostics and health management of FAST cable-net structure based on digital twin technology

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Research in Astronomy and Astrophysics 2020年第5期20卷 109-116页

作者： Qing-Wei Li Peng Jiang Hui Li National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)will be fully commissioned later in *** commissioned,operation and maintenance of FAST will be the most prominent *** unique working mode of active shape-changing of FAST cable-net structure makes the traditional maintenance way,which combines routine inspection with preventive maintenances not only expensive,but also unable to effectively avoid potential risks in ***,it is necessary to develop an economical and reliable operation/maintenance technology for FAST cable-net *** this paper,a Prognostics and Health Management(PHM)system is proposed based on the advanced Digital Twin(DT)*** the finite element analysis of DT model,the current safety status of FAST cablenet is evaluated,and the fatigue life of components in the cable-net is *** Condition-Based Maintenance(CBM)of FAST cable-net structure can be *** PHM system described in this paper can effectively guarantee the healthy and safe operation of the FAST cable-net structure,greatly improve the maintenance efficiency and reduce the cost for maintenance works.

关键词： telescopes astronomical instrumentation methods and techniques methods:analytical methods:data analysis