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FAST ultra-wideband observation of abnormal emission-shift events of PSR B0919+06

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Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 32-37页

作者： ye-zhao yu Bo Peng Kuo Liu ChengMin Zhang Lin Wang FeiFei Kou JiGuang Lu Meng yu FAST Collaboration CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China School of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China Max-Planck-Institut fur Radioastronomie Auf dem Hugel 69Bonn 53121Gennany 不详

PSR B0919+06 is known for its abnormal emission phenomenon, where the pulse emission window occasionally shifts progressively in longitude and returns afterwards. The physical mechanism behind this phenomenon is still under investigation. In this paper, we present our ultra-wideband observation of this pulsar using the Five-hundred-meter Aperture Spherical radio Telescope(FAST), with simultaneous measurements in the frequency ranges 280-780 and 1250-1550 MHz. We have identified three abnormal events, each of which becomes less apparent as the frequency decreases. At 1400 MHz, the averaged profile slightly shifted after the first and third abnormal events, implying a relationship between abnormal event and profile variation. We also found a linear trend in the left-edge position of the averaged profiles between the first and third events as well as after the third event, suggesting the existence of a slow-drifting mode between the two major events. The second event has a comparatively small shift in phase and is thus categorized as a "small flare state". During the third event, a sequence of approximately nine pulses was seen to significantly weaken in all frequency bands, likely associated with the pseudo-nulling observed at 150 MHz.A three-component de-composition analysis of the normal averaged profiles shows that the trailing component is dominant at our observing frequencies, while the centre component has a comparatively steeper spectrum. We found the overall flux density in an abnormal event to slightly differ from that in an ordinary state, and the difference shows a frequency dependence. A comparison of the normal, abnormal and dimmed averaged profile indicates that the leading component is likely to be stable in all states.

关键词： pulsar B0919+06 radio

Study of three rotating radio transients with FAST

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Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 25-31页

作者： JiGuang Lu Bo Peng Kuo Liu Peng Jiang YouLing yue Meng yu ye-zhao yu FeiFei Kou Lin Wang FAST Collaboration CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Guizhou Radio Astronomy Observatory Chinese Academy of SciencesGuiyang 550025China Max-Planck-lnstitut fiir Radioastronomie Bonn D-53121Germany College of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China 不详

Rotating radio transients(RRATs) are peculiar astronomical objects whose emission mechanism remains under *** this paper, we present observations of three RRATs, J1538+2345, J1854+0306 and J1913+1330, carried out with the Fivehundred-meter Aperture Spherical radio Telescope(FAST). Specifically, we analyze the mean pulse profiles and temporal flux density evolutions of the RRATs. Owing to the high sensitivity of FAST, the derived burst rates of the three RRATs are higher than those in previous reports. RRAT J1854+0306 exhibited a time-dynamic mean pulse profile, whereas RRAT J1913+1330 showed distinct radiation and nulling segments on its pulse intensity trains. The mean pulse profile variation with frequency is also studied for RRAT J1538+2345 and RRAT J1913+1330, and the profiles at different frequencies could be well fitted with a cone-core model and a conal-beam model, respectively.

关键词： radiation mechanisms radio pulsars

A New Emission Mode of PSR B1859+07

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Research in Astronomy and Astrophysics 2023年第10期23卷 176-183页

作者： Tao Wang P.F.Wang J.L.Han Yi Yan ye-zhao yu Feifei Kou National Astronomical Observatories Chinese Academy of SciencesBeijing 100101China School of Astronomy and Space Science University of Chinese Academy of SciencesBeijing 100049China The key Laboratory for Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China Qiannan Normal University for Nationalities Duyun 558000China Xinjiang Astronomical Observatories Chinese Academy of SciencesUrumqi 830011China

Previous studies have identified two emission modes in PSR B1859+07: a normal mode that has three prominent components in the average profile, with the trailing one being the brightest, and an anomalous mode(i.e., the A mode) where emissions seem to be shifted to an earlier phase. Within the normal mode, further analysis has revealed the presence of two submodes, i.e., the cW mode and c B mode, where the central component can appear either weak or bright. As for the anomalous mode, a new bright component emerges in the advanced phase while the bright trailing component in the normal mode disappears. New observations of PSR B1859+07 using the Fivehundred-meter Aperture Spherical Radio Telescope(FAST) have revealed the existence of a previously unknown emission mode, dubbed the Af mode. In this mode, all emission components seen in the normal and anomalous modes are detected. Notably, the mean polarization profiles of both the A and Af modes exhibit a jump in the orthogonal polarization angle modesin the bright leading component. The polarization angles for the central component in the original normal mode follow two distinct orthogonal polarization modes in the A and Af modes respectively. The polarization angles for the trailing component show almost the same but a small systematic shift in the A and Af modes, roughly following the values for the c W and cB modes. Those polarization features of this newly detected emission mode imply that the anomalous mode A of PSR B1859+07 is not a result of “phase shift”or “swooshes” of normal components, but simply a result of the varying intensities of different profile ***, subpulse drifting has been detected in the leading component of the Af mode.

关键词： (stars:)pulsars:individual(PSR B1859+07) polarization plasmas

The radiation structure of PSR B2016+28 observed with FAST

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Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 38-51页

作者： JiGuang Lu Bo Peng RenXin Xu Meng yu Shi Dai WeiWei Zhu ye-zhao yu Peng Jiang YouLing yue Lin Wang FAST Collaboration CAS Key Laboratory of FAST National Astronomical Obserx'atoriesChinese Academy of SciencesBeijing 100101China Guizhou Radio Astronomy Observatory Chinese Academy of SciencesGuiyang 550025China School of Physics and Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China CSIRO Astronomy and Space Science Australia Telescope National Facility Epping NSW 1710Australia College of Astronomy and Space Sciences University of Chinese Academy of SciencesBeijing 100049China 不详

With the largest dish Five-hundred-meter Aperture Spherical radio Telescope(FAST), both the mean and single pulses of PSR B2016+28, especially including the single-pulse structure, are investigated in detail in this study. The mean pulse profiles at different frequencies can be well fitted in a conal model, and the peak separation of intensity-dependent pulse profiles increases with intensity. The integrated pulses are obviously frequency dependent(pulse width decreases by ～20% as frequency increases from 300 to 750 MHz), but the structure of single pulses changes slightly(the corresponding correlation scale decreases by only～1%). This disparity between mean and single pulses provides independent evidence for the existence of the RS-type vacuum inner gap, indicating a strong bond between particles on the pulsar surface. Diffused drifting sub-pulses are analyzed. The results show that the modulation period along pulse series(P_3) is positively correlated to the separation between two adjacent sub-pulses(P_2). This correlation may hint a rough surface on the pulsar, eventually resulting in the irregular drift of sparks. All the observational results may have significant implications in the dynamics of pulsar magnetosphere and are discussed extensively in this paper.

关键词： radiation mechanisms mathematical procedures and computer techniques radio pulsars

FAST interstellar scintillation observation of PSR B1929+10 and PSR B1842+14

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Research in Astronomy and Astrophysics 2020年第5期20卷 175-180页

作者： Ju-Mei Yao Wei-Wei Zhu Pei Wang Di Li Ji-Guang Lu Fei-Fei Kou ye-zhao yu Bo Peng FAST Collaboration CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Xinjiang Astronomical Observatories Chinese Academy of SciencesUrumqi 830011China School of Physics and Electronics Qiannan Normal University for NationalitiesDuyun 558000China

In this paper,we present the Five-hundred-meter Aperture Spherical radio Telescope(FAST)observations of PSRs B1929+10 and B1842+*** analysis of the pulsars’scintillation pattern,we detected the known scintillation arc from PSR B1929+10 and two previously undetected scintillation arcs from B1842+*** find that the B1929+10 arc’s curvature scales with observing frequency asη-∝ν-2.1±0.1 andη+∝ν-1.8±0.2,consistent with Arecibo results and the theoretical expectations ofη∝ν-*** the arc curvature,we infer the scattering screen to be located at 0.20±0.02 kpc from the Earth,close to what was measured by RadioAstron at 324 *** B1842+14,we find two scintillation arcs for the first *** arcs’curvatures imply that they are caused by two scattering screens located at a distance of 0.3±0.2 kpc and 1.6±0.6 kpc from the Earth,*** screen distance uncertainties mainly come from the uncertainty in pulsar’s dispersion measure(DM)-derived *** present these FAST scintillation observations and discuss the future prospect of FAST pulsar scintillation study.

关键词： FAST pulsars:general ISM:structure

Dish Verification Antenna China for the SKA:design, verification and status

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Research in Astronomy and Astrophysics 2019年第6期19卷 97-108页

作者： Biao Du Yang Wu yuan-Peng Zheng Xiao-Ming Chai Guo-Xi Liu Hai-Dong Wang Yi-Fan Zhang Sheng-Hua yu Bin Liu ye-zhao yu Hong-Wei Xi Long Chen Lei yu Dong-Liang Liu Cheng-Jin Jin Bo Peng The 54^th Research Institute of CETC Shijiazhuang 050081 China Joint Laboratory of Radio Astronomy Technology Beijing 100101 China National Astronomical Observatories Chinese Academy of Sciences Beijing 100101 China

The Square Kilometre Array(SKA) will be the world’s largest synthesis radio telescope, which is designed to answer major scientific questions such as those relating to the cosmic origin and fundamental forces in the universe. With the SKA entering into the phase of pre-construction, more than 100 institutes in about 20 countries including China have been involved in the associated key technology *** Dish Verification Antenna China(DVA-C) is a concept prototype which has been built to meet the requirements of the SKA’s scientific goals. It utilizes a unique skin-and-rib structure with single-piece panel reflectors. This paper presents details on the design and measured performances of DVA-C, as well as the preliminary observational results. Current applications of the DVA-C are also introduced.

关键词： Square Kilometre Array radio telescope dish-single-piece panel

Effect of cholesterol metabolism on hepatolithiasis

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World Journal of Gastroenterology 2025年第1期31卷 157-162页

作者： Lin Zheng Zi-yu ye Jun-Ji Ma Department of Gastroenterology The Second Hospital of Hebei Medical UniversityHebei Key Laboratory of GastroenterologyHebei Institute of GastroenterologyHebei Clinical Research Center for Digestive DiseasesNo.215 Heping West RoadShijiazhuang 050000Hebei ProvinceChina

Surgical intervention is currently the primary treatment for hepatolithiasis;how-ever,some patients still experience residual stones and high recurrence rates after *** metabolism seems to play an important role in hepatoli-thiasis pathogenesis.A high cholesterol diet is one of the significant reasons for the increasing incidence of ***,regular diet and appropriate medical intervention are crucial measures to prevent hepatolithiasis and reduce recurrence rate after *** dietary cholesterol and drugs that increase cholesterol stone solubility are key therapeutic approaches in treating *** article discusses the cholesterol metabolic pathways related to the pathogenesis of hepatolithiasis,as well as food intake and targeted therapeutic drugs.

关键词： Hepatolithiasis Cholesterol metabolism High-fat diet 3-hydroxy-3-methylglutaryl-coenzyme A reductase Interlobular bile duct

Unraveling the significance of cobalt on transformation kinetics,crystallography and impact toughness in high-strength steels

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International Journal of Minerals,Metallurgy and Materials 2025年第2期32卷 380-390页

作者： Yishuang yu Jingxiao zhao Xuelin Wang Hui Guo Zhenjia Xie Chengjia Shang Collaborative Innovation Center of Steel Technology University of Science and Technology BeijingBeijing 100083China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

This work reveals the significant effects of cobalt(Co)on the microstructure and impact toughness of as-quenched highstrength steels by experimental characterizations and thermo-kinetic *** results show that the Co-bearing steel exhibits finer blocks and a lower ductile-brittle transition temperature than the steel without ***,the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to *** improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant ***,the addition of Co induces a larger transformation driving force and a lower bainite start temperature(BS),thereby contributing to the refinement of blocks and the increase of the V1/V2 variant *** findings would be instructive for the composition,microstructure design,and property optimization of high-strength steels.

关键词： high-strength steel cobalt transformation kinetics crystallography impact toughness

High-temperature-tolerant flexible supercapacitors: Gel polymer electrolytes and electrode materials

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Journal of Energy Chemistry 2025年第1期100卷 426-457页

作者： Chong Peng Xinyi Huang Mingwei zhao Shuling Liao Quanhong Yang Nianjun Yang Siyu yu School of Chemistry & Chemical Engineering Southwest University Nanoyang Group Tianjin Key Laboratory of Advanced Carbon and Electrochemical Energy Storage School of Chemical Engineering and Technology and Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin University Department of Chemistry & IMO-IMOMEC Hasselt University

The development of flexible supercapacitors(FSCs) capable of operating at high temperatures is crucial for expanding the application areas and operating conditions of supercapacitors. Gel polymer electrolytes and electrode materials stand as two key components that significantly impact the efficacy of hightemperature-tolerant FSCs(HT-FSCs). They should not only exhibit high electrochemical performance and excellent flexibility, but also withstand intense thermal stress. Considerable efforts have been devoted to enhancing their thermal stability while maintaining high electrochemical and mechanical performance. In this review, the fundamentals of HT-FSCs are outlined. A comprehensive overview of state-of-the-art progress and achievements in HT-FSCs, with a focus on thermally stable gel polymer electrolytes and electrode materials is provided. Finally, challenges and future perspectives regarding HT-FSCs are discussed, alongside strategies for elevating operational temperatures and *** review offers both theoretical foundations and practical guidelines for designing and manufacturing HT-FSCs, further promoting their widespread adoption across diverse fields.

关键词： Flexible supercapacitors High-temperature tolerance Gel polymer electrolytes Electrode materials