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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 Zhao1,2.1 {2.,chinese academy of sciences,Beijing 100012.china 2.key laboratory of optical astronomy,{2.,chinese academy of sciences,Beijing 100012.china national astronomical observatories Chinese Academy of Sciences Beijing 100012 China key laboratory of {2. 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,chinese {2. 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

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

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 Wang Ye-Ping Li Ya-jun Zhang Liang Zhang Yi-Zhong Zeng Jie Zhang national astronomical observatories / Nanjing Institute of astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China key laboratory of {2. 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 {2. 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

Test observations that search for metal-poor stars with the Guoshoujing Telescope (LAMOST)

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Research in astronomy and Astrophysics 2010年第8期10卷 753-760页

作者： Hai-Ning Li Gang Zhao Norbert Christlieb A-Li Luo Jing-Kun Zhao Yong-Heng Zhao Jian-jun Chen Zhong-Rui Bai key laboratory of {2. astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of chinese academy of sciences Beijing 100049 China Zentrum fur Astronomie der Universitat Heidelberg Landessternwarte Konigstuhl 12 69117 Heidelberg Germany

Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on properties of the very early stage of the chemical history of the Galaxy and have been investigated for decades. The unique design of the Guoshoujing Telescope （LAMOST）, such as its large field and multi-object observational capability, enables it to be an excellent tool for searching for these metal-poor stars in the Milky Way. This work reports the result of test observations which search for metal-poor stars with LAMOST, during which nine candidate metal-poor stars with [Fe/H] ≤ - 1.0 were newly detected based on the low-resolution spectroscopic observations of the LAMOST commissioning data. The sample of stars demonstrates the efficiency of selecting from the input catalog, as well as the ability of LAMOST to enlarge the sample of metal-poor stars in the Milky Way. Furthermore, the sample of stars could be used for future calibrations of the LAMOST stellar pa- rameter pipeline.

关键词： Galaxy stellar content -- surveys -- stars Population Ⅱ

Progress and prospects of chiral nanomaterials for biosensing platforms

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Rare Metals 2024年第6期43卷 2469-2497页

作者： Yu-Cheng Ouyang Bong-jun Yeom Yuan Zhao Wei ma School of Food Science and Technology State Key Laboratory of Food Science and ResourcesJiangnan UniversityWuxi 214122China key laboratory of Synthetic and Biological Colloids Ministry of EducationSchool of Chemical and Material EngineeringJiangnanUniversityWuxi214122China Department of Chemical Engineering Hanyang UniversitySeoul04763RepublicofKorea

Chiral nanomaterials have distinct chiroptical properties of preferential interactions to circularly polarized ***-based biosensors have emerged for detection of biomolecules,ions and cells in recent *** review provides an extensive overview of biosensors based on chiral nanomaterials,starting with approaches to chiral nanomaterials construction in terms of fabrication *** of chiral nanomaterials and their biosensor applications is presented for different material types,with special emphasis on the role and importance of material properties and signal generation in *** assessed the technological prospects of the emerging fields of chiral construction,circularly polarized luminescence,Raman optical activity and so on along with their current *** venues for future research on chiral nanomaterials in fabrication,biosensing,disease diagnosis and treatment are also presented in the review.

关键词： Chiral nanomaterials Circular dichroism Biosensors

Hydrogel-Assisted Electrokinetics for High-Resolution and Non-invasive Flow Monitoring in Microfluidic Chips

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chinese Journal of Chemistry 2024年第6期42卷 571-577页

作者： Na Zhao Yanni ma Zehua Yu jun Huang Xiangqian Fu Tao Qiu Kang Liu MOE key laboratory of Hydraulic {2.chinery Transients School of Power and Mechanical EngineeringWuhan UniversityWuhanHubei430072 China Department of Urology Renmin Hospital of Wuhan UniversityWuhanHubei430072 China Department of Organ Transplantation Renmin Hospital of Wuhan UniversityWuhanHubei430072 China

Convenient non-invasive flow monitoring would facilitate the operation and control in microfluidic chips,but is challenging due to the small space of microchannels and complex operation required in traditional optical *** this work,we propose a novel non-invasive strategy to probe microfluidic flows via streaming potential *** sealing one side of the microchannel with a piece of hydrogel film,streaming potential inside the channel can be clearly detected by electrodes at outer surface of the hydrogel due to ion diffusion in the *** is detected without sensors contacting with the internal ***,the electrodes shape like a tiny probe,which can move around mapping the flow distribution in a chip with the spatial resolution of 1 mm and flow rate detection limit of 3μL·min–*** inside the channels can also be detected,due to the fluctuation of streaming voltage when gas-liquid interface flows through the electrode,showing an easy and potential way for multi-functional flow monitoring in microfluidic chips.

关键词： Microfluidics Hydrogels Electrokinetics Flow monitoring Non-invasive Sensor Charge transport

Mode division multiplexing reconstructive spectrometer with an all-fiber photonics lantern

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Frontiers of Optoelectronics 2024年第3期17卷 29-38页

作者： junrui Liang jun Ye Xiaoya {2. Yao Lu jun Li Jiangming Xu Zilun Chen Jinyong Leng Zongfu Jiang Pu Zhou College of Advanced Disciplinary Studies National University of Defense TechnologyChangsha 410073China Nanhu Laser laboratory National University of Defense TechnologyChangsha 410073China Hunan Provincial key laboratory of High Energy Laser Technology National University of Defense TechnologyChangsha 410073China Space Engineering University Beijing 101416China

This study presents a high-accuracy,all-fber mode division multiplexing(MDM)reconstructive spectrometer(RS).The MDM was achieved by utilizing a custom-designed 3×1 mode-selective photonics lantern to launch distinct spatial modes into the multimode fber(MMF).This facilitated the information transmission by increasing light scattering processes,thereby encoding the optical spectra more comprehensively into speckle *** resolution of 2.pm and the recovery of 2.00 spectral channels were *** to methods employing single-mode excitation and two-mode excitation,the three-mode excitation method reduced the recovered error by 88%and 50%respectively.A resolution enhancement approach based on alternating mode modulation was proposed,reaching the MMF limit for the 3 dB bandwidth of the spectral correlation *** proof-of-concept study can be further extended to encompass diverse programmable mode *** is not only succinct and highly efcient but also well-suited for a variety of high-accuracy,high-resolution spectral measurement scenarios.

关键词： High-accuracy Resolution enhancement Reconstructive spectrometer Mode division multiplexing Photonics lantern

Gradient sparsification for efficient wireless federated learning with differential privacy

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Science china(Information {2.) 2024年第4期67卷 272-288页

作者： Kang WEI jun LI Chuan ma Ming DING Feng SHU Haitao ZHAO Wen CHEN Hongbo ZHU School of Electronic and optical Engineering Nanjing University of Science and Technology Zhejiang Lab key laboratory of Computer Network and Infor{2.tion Integration(Southeast University) Ministry of Education Data61 Commonwealth Scientific and Industrial Research Organisation School of Information and Communication Engineering Hainan University School of Communications and Information Engineering Nanjing University of Posts and Telecommunications School of Electronic Information and Electrical Engineering Shanghai Jiao Tong University

Federated learning(FL) enables distributed clients to collaboratively train a machine learning model without sharing raw data with each other. However, it suffers from the leakage of private information from uploading models. In addition, as the model size grows, the training latency increases due to the limited transmission bandwidth and model performance degradation while using differential privacy(DP)protection. In this paper, we propose a gradient sparsification empowered FL framework with DP over wireless channels, to improve training efficiency without sacrificing convergence performance. Specifically, we first design a random sparsification algorithm to retain a fraction of the gradient elements in each client’s local model, thereby mitigating the performance degradation induced by DP and reducing the number of transmission parameters over wireless channels. Then, we analyze the convergence bound of the proposed algorithm, by modeling a non-convex FL problem. Next, we formulate a time-sequential stochastic optimization problem for minimizing the developed convergence bound, under the constraints of transmit power, the average transmitting delay, as well as the client’s DP requirement. Utilizing the Lyapunov drift-plus-penalty framework, we develop an analytical solution to the optimization problem. Extensive experiments have been implemented on three real-life datasets to demonstrate the effectiveness of our proposed algorithm. We show that our proposed algorithms can fully exploit the interworking between communication and computation to outperform the baselines, i.e., random scheduling, round robin, and delay-minimization algorithms.

关键词： federated learning differential privacy gradient sparsification Lyapunov drift convergence analysis

Development of a Front End Array for Broadband Phased Array Receiver

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Research in astronomy and Astrophysics 2024年第4期24卷 60-70页

作者： Kai Wang Liang Cao jun ma Xue-Feng Duan Hao Yan mao-Zheng Chen Yun-Wei Ning Xinjiang astronomical Observatory Chinese Academy of SciencesUrumqi 8300lChina University of the chinese academy of sciences Beijing 100049China Xinjiang key laboratory of Microwave Technology Urumqi 830011China

The receiver is a signal receiving device placed at the focus of the *** order to improve the observation efficiency,the concept of phased array receiver has been proposed in recent years,which places a small phased array at the focal plane of the reflector,and flexible pattern and beam scanning functions can be achieved through a beamforming *** combined with the element multiplexing,all beams within the entire field of view can be observed simultaneously to achieve continuous sky *** article focuses on the front-end array of phased array receiver at 0.7-1.8 GHz for QiTai Telescope,and designs a Vivaldi antenna array of PCB structure with dual line *** polarization antenna is designed to arrange in a rectangle manner by 11×*** on the simulation results of the focal field,32.18,and eight elements were selected to form one beam at 0.7,1.2.,and1.8 *** analog beamforming network was constructed,and the measured gains of axial beam under uniform weighting were 19.32.13.72.and 15.2. *** the beam scanning method of reflector antenna,the pattern test of different position element sets required for PAF beam scanning was carried out under independent *** pattern optimization at 1.2. GHz was carried out by weighting method of conjugate field *** with uniform weighting,the gain,sidelobe level,and main beam direction under conjugate field matching have been *** the above test and simulation results are slightly different,which is related to the passive array and laboratory testing condition,the relevant work has accumulated experience in the development of the front-end array for the phased array receiver,and has good guiding significance for future performance verification after the array is installed on the telescope.

关键词： telescopes instrumentation:detectors techniques:radar astronomy