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Thermal analysis of the baffle structure of the Solar Space Telescope

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

作者： li rong1,2.3.& wang sen1,{2.,Chinese academy of {4.,Beijing 100012.china 2.Graduate University of Chinese academy of {4.,Beijing 10004.,china 3 Key Laboratory of Solar Activity,national astronomical observatories of Chinese academy of {4.,Beijing 100012.china 1. national astronomical {2. 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 4.00 mm,the internal shield of radius 4.4.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

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Regulation mechanism of EM parameters in natural ferrite and its application in microwave absorbing materials

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Science china(Technological sciences) 2006年第1期49卷 38-49页

作者： ZHENG Yongchun1,2. wang Shijie2. FENG Junming2. {4. Chunlai1, OUYANG Ziyuan1,2. {4.U Jianzhong1 & {4. Xiaobiao2.1. national astronomical observatories, Chinese academy of sciences, Beijing {14., china 2. State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese academy of sciences, Guiyang 550002. china 1. national astronomical {2. Chinese Academy of Sciences Beijing 100012 China 2. State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China

Electromagnetic (EM) parameters (ε ′, ε ″, μ ′, μ″ ) of several M2.Fe2.4.and Fe2.3 type natural ferrites with different geological occurrences are measured in this pa-per. The measurement results show that EM parameters of a magmatic-occurring natural ferrite is very different from other types occurring from sedimentary-metamorphic iron deposit, hydrothermal vein iron deposit, outer contact of magmatic iron deposit. It has potential to be used as magnetic absorbent in microwave absorbing materials. After min-eral separation and concentration, this magmatic-occurring natural ferrite was processed into type A ferrite absorbent. Type A natural ferrite absorbent is a kind of magnetic material with low dielectric constants, high magnetic conductivity and high EM loss. Its EM pa-rameters are ε ′ = 58.60, ε ″ = 10.0, μ ′ = 1.2.1.5, μ ″ = 1.0-1.2. respectively. In order to illuminate the regulation mechanism of EM parameters, we studied the chemical and mineral composition of type A ferrite absorbent. There is high concentration of natural impurities, which regulate the EM parameters of type A ferrite greatly. For comparison, the other types of natural ferrite, single-phase magnetite and two-phase iron minerals (ilmen-ite and magnetite), have few impurity. Thus regulation mechanism of EM parameters was absent in these ferrites. As a result, the regulation of EM parameters is advantageous to develop type A natural ferrite as excellent absorbent, lowers the reflectivity coefficients and enhances the absorbing efficiency of MAM made from it. Furthermore, the impurities in type A natural ferrite and its effects on EM parameters are very difficult to simulate in the synthesize ferrite. The carbonyl-iron powder is another kind of absorbent that is used ex-tensively in MAM. To compare the absorbing properties of these two absorbent, type A natural ferrite and carbonyl-iron powder were mixed with rubber and processed into mi-crowave absorbing sheets with the same procedures and tec

关键词： natural impure ferrite, complex permittivity, complex permeability, microwave absorbing materials.

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Study of the primordial lithium abundance

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Science china(Physics,Mechanics & Astronomy) 2011年第S1期54卷 67-72页

作者： li ZhiHong1, li ErTao1, SU Jun1, li YunJu1, BAI XiXiang1, GUO Bing1, wang YouBao1, CHEN YongShou1, HOU SuQing1, ZENG Sheng1, liAN Gang1, SHI Jianrong2.& liU WeiPing1 1 china Institute of Atomic Energy, Beijing 102.13, china 2.9} astronomical observatories, Chinese {12. of sciences, Beijing 100012, china china Inst Atom Energy Beijing 102413 Peoples R China Chinese Acad Sci Natl Astron Observ Beijing 100012 Peoples R China

lithium isotopes have attracted an intense interest because the abundance of both 6li and 6li from big bang nucleosynthesis (BBN) is one of the puzzles in nuclear astrophysics. Many investigations of both astrophysical observation and nucleosynthesis calculation have been carried out to solve the puzzle, but it is not solved yet. Several nuclear reactions involving lithium have been indirectly measured at {4. Institute of Atomic Energy, Beijing. The Standard BBN (SBBN) network calculations are then performed to investigate the primordial lithium abundance. The result shows that these nuclear reactions have minimal effect on the SBBN abundances of 6li and 7li.

关键词： big bang nucleosynthesis element abundance nuclear reaction network

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A Hierarchical Method for Locating the Interferometric Fringes of Celestial Sources in the Visibility Data

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Research in Astronomy and Astrophysics 2024年第3期24卷 110-128页

作者： rong Ma Ruiqing Yan Hanshuai Cui Xiaochun Cheng Jixia li Fengquan Wu Zongyao Yin Hao {2. Wenyi Zeng Xianchuan Yu School of Artificial Intelligence Beijing Normal UniversityBeijing 100875China Department of Computer Science Swansea UniversitySwanseaSA18ENUK national astronomical {2. Chinese Academy of SciencesBeijing 100101China

In source detection in the Tianlai project,locating the interferometric fringe in visibility data accurately will influence downstream tasks drastically,such as physical parameter estimation and weak source *** that traditional locating methods are time-consuming and supervised methods require a great quantity of expensive labeled data,in this paper,we first investigate characteristics of interferometric fringes in the simulation and real scenario separately,and integrate an almost parameter-free unsupervised clustering method and seeding filling or eraser algorithm to propose a hierarchical plug and play method to improve location ***,we apply our method to locate single and multiple sources’interferometric fringes in simulation ***,we apply our method to real data taken from the Tianlai radio telescope ***,we compare with unsupervised methods that are state of the *** results show that our method has robustness in different scenarios and can improve location measurement accuracy effectively.

关键词： methods data analysis-techniques image processing-techniques interferometric

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Spectroscopic and photometric observations of unidentified ultraviolet variable objects in the GUVV-2.Catalog

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Research in Astronomy and Astrophysics 2011年第7期11卷 833-842页

作者： You li Jing wang Jian-Yan Wei Xiang-Tao He Department of Astronomy Beijing Normal University Beijing 100875 China national astronomical {2. Chinese Academy of Sciences Beijing 100012 China

An NUV-optical diagram composed from sources from the second Galaxy Evolution Explorer（GALEX） Ultraviolet Variability（GUVV-2. Catalog provides us with a method to tentatively classify the unknown GUVV-2.sources by their NUV-optical *** the purpose of testing the correctness and generality of the method,we carry out a program on the spectroscopic observations of the unidentified GUVV-2.*** spectroscopic identification of these 37 sources are 19 type-A to-F stars,10 type-G to-K stars and 7 M dwarf stars together with an *** also pre{2.t the light curves in the R-band for two RR Lyrae star candidates selected from the NUV-optical diagram,both of which undergo cyclic *** their light curves and colors,we classify them as RR Lyrae *** confirm the re-sults,we show a color-color diagram for the 37 newly identified spectroscopic objects compared with previously identified ones,which are consistent with our previous re-sults,indicating that the ultraviolet variable sources can initially be classified by their NUV/optical color-color diagram.

关键词： stars:variables:general—galaxies:active—methods:observational—ultraviolet emission

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Support Vector Machine combined with K-Nearest Neighbors for Solar Flare Forecasting

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Chinese Journal of Astronomy and Astrophysics 2007年第3期7卷 441-447页

作者： rong li Hua-Ning {2. Han He Yan-Mei Cui Zhan-Le Du national astronomical {2. Chinese Academy of Sciences Beijing 100012

A method combining the support vector machine （SVM） the K-Nearest Neighbors （KNN）, labelled the SVM-KNN method, is used to construct a solar flare forecasting model. Based on a proven relationship between SVM and KNN, the SVM-KNN method improves the SVM algorithm of classification by taking advantage of the KNN algorithm according to the distribution of test samples in a feature space. In our flare forecast study, sunspots and 10cm radio flux data observed during Solar Cycle 2. are taken as predictors, and whether an M class flare will occur for each active region within two days will be predicted. The SVM- KNN method is compared with the SVM and Neural networks-based method. The test results indicate that the rate of correct predictions from the SVM-KNN method is higher than that from the other two methods. This method shows promise as a practicable future forecasting model.

关键词： Sun flare - Sun sunspot - Sun activity - Sun magnetic fields

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Workspace and rotational capability analysis of a spatial 3-DoF parallel manipulator

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Progress in Natural Science:Materials International 2004年第11期 60-67页

作者： liU Xinjun 1*, wang Jinsong 1, wang Qiming 2.and li Tiemin 1(1. Manufacturing Engineering Institute, Department of Precision Instruments, Tsinghua University, Beijing 100084. china 2. national astronomical observatories, Chinese academy of sciences, Beijing 100012, china) ManufacturingEngineeringInstitute DepartmentofPrecisionInstrumentsTsinghuaUniversityBeijing100084China nationalastronomical{2. ChineseAcademyofSciencesBeijing100012China

The analysis on the workspace and rotational capability of HANA, a spatial 3-DoF parallel manipulator, is concerned. The parallel manipulator consists of a base plate, a movable platform, and three connecting legs. The moving platform has three degrees of freedom (DoFs) which are two translations and one rotation, with respect to the base plate. The new parallel manipulator is very interesting for the reason of no singularity in the workspace, the single-DoF joint architecture and high rotational capability of the moving platform. The inverse kinematics problem is described in a closed-form, which is very useful to pre{2.t the workspace geometrically. The constant-orientation and reachable workspaces for the manipulator are analyzed firstly. The index that is used to evaluate the rotational capability of the manipulator is defined and discussed in detail. Finally, the distribution of rotational capability index on the workspace is pre{2.ted, which helps us know how much the index is at different point. The parallel manipulator has wide application in the fields of industrial robots, simulators, micro-motion manipulators, and parallel kinematics machines.

关键词： parallel manipulator singularity rotational capability workspace kinematics.

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Applying Hybrid Clustering in Pulsar Candidate Sifting with Multi-modality for FAST Survey

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Research in Astronomy and Astrophysics 2024年第3期24卷 283-296页

作者： Zi-Yi You Yun-rong Pan Zhi Ma li Zhang Shuo Xiao Dan-Dan Zhang Shi-Jun Dang Ru-Shuang Zhao Pei {2. Ai-Jun Dong Jia-Tao Jiang Ji-Bing Leng Wei-An li Si-Yao li School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550025China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guizhou Normal UniversityGuiyang 550025China College of Big Data and Information Engineering Guizhou UniversityGuiyang 550025China CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Key Laboratory of Information and Computing Guizhou Province Guizhou Normal UniversityGuiyang 550001China School of Big data and Computer Science Guizhou Normal UniversityGuiyang 550025China Guizhou Software Engineering Research Center Guiyang 550000China

Pulsar search is always the basis of pulsar navigation,gravitational wave detection and other research ***,the volume of pulsar candidates collected by the Five-hundred-meter Aperture Spherical radio Telescope(FAST)shows an explosive growth rate that has brought challenges for its pulsar candidate filtering ***,the multi-view heterogeneous data and class imbalance between true pulsars and non-pulsar candidates have negative effects on traditional single-modal supervised classification *** this study,a multi-modal and semi-supervised learning based on a pulsar candidate sifting algorithm is presented,which adopts a hybrid ensemble clustering scheme of density-based and partition-based methods combined with a feature-level fusion strategy for input data and a data partition strategy for *** on both High Time Resolution Universe SurveyⅡ(HTRU2.and actual FAST observation data demonstrate that the proposed algorithm could excellently identify pulsars:On HTRU2.the precision and recall rates of its parallel mode reach0.981 and 0.988 *** FAST data,those of its parallel mode reach 0.891 and 0.961,meanwhile,the running time also significantly decreases with the increment of parallel nodes within ***,we can conclude that our algorithm could be a feasible idea for large scale pulsar candidate sifting for FAST drift scan observation.

关键词： methods data analysis-surveys-methods numerical

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An experimental indoor phasing system based on active optics using dispersed Hartmann sensing technology in the visible waveband

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Research in Astronomy and Astrophysics 2011年第9期11卷 1111-1122页

作者： Yong Zhang Gen-rong liu Yue-Fei {2. Ye-Ping li Ya-Jun Zhang liang Zhang Yi-Zhong Zeng Jie Zhang national astronomical {2. / Nanjing Institute of astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China Key Laboratory of astronomical Optics ＆ Technology Nanjing Institute of Astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China Graduate University of Chinese academy of sciences Beijing 100049 China

A telescope with a larger primary mirror can collect much more light and resolve objects much better than one with a smaller mirror, and so the larger version is always pursued by astronomers and astronomical technicians. Instead of using a monolithic primary mirror, more and more large telescopes, which are currently being planned or in construction, have adopted a segmented primary mirror design. Therefore, how to sense and phase such a primary mirror is a key issue for the future of extremely large optical/infrared telescopes. The Dispersed Fringe sensor （DFS）, or Dispersed Hartmann sensor （DHS）, is a non-contact method using broadband point light sources and it can estimate the piston by the two-directional spectrum formed by the transmissive grating＇s dispersion and lenslet array. Thus it can implement the combination of co-focusing by Shack-Hartmann technology and phasing by dispersed fringe sensing technologies such as the template-mapping method and the Hartmann method. We introduce the successful design, construction and alignment of our dis- persed Hartmann sensor together with its design principles and simulations. We also conduct many successful real phasing tests and phasing corrections in the visible waveband using our existing indoor segmented mirror optics platform. Finally, some conclusions are reached based on the test and correction of experimental results.

关键词： astronomical instrumentation -- methods and techniques -- instrumen- tation: active optics -- adaptive optics

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Can Asymmetry of Solar Activity be Extended into Extended Cycle?

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Chinese Journal of Astronomy and Astrophysics 2002年第1期2卷 66-70页

作者： Ke－Junli Jing－Xiuwang 等 YunnanObservatory ChineseAcademyofSciencesKunming650011 nationalastronomical{2. ChineseAcademyofSciencesBeijing100012

With the use of the Royal Greenwich Observatory data set of sunspot groups, an attempt is made to examine the north-south asymmetry of solar activity in the 'extended' solar cycles. It is inferred that the asymmetry e... 详细信息

关键词： Sun: sunspot - Sun: active cycle - Sun: activity

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