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Science China(Technological Sciences) 2012年第5期55卷 1281-1286页

作者： HE Fang zhang beichen HUANG DeHong SOA Key LaboratoryJbr Polar Science Polar Research Institute of ChinaShanghai 200136China

Based on the ionosphere observation data obtained by EISCAT Svalbard Radar (ESR) in solar minimum year-2007, we analyzed diurnal variations of F2-peak electron density (NmF2) in four seasons under disturbed and quiet geomagnetic conditions. It indicated that the soft precipitation electron had an evident effect on the NmF2 increase at magnetic noon in spring, summer and autumn and the electron precipitation effects were prominent in winter. The comparison between the IRI-2007 model and the observation exhibited that the IRI (International Reference Ionosphere) model had a better NmF2 prediction when the photoionization was dominant during the polar day, but worse when the electron precipitation was dominant during the polar night. We showed that the electrons in lower energy band decreased when the geomagnetic disturbance went greater, which resulted in the lower NmF2. By analyzing the spectrum of precipitation electron under different geomagnetic conditions, it was found that this phenomenon was induced by the energy flux enhancement of precipitation electron of low energy.

关键词： electron density solar minimum electron precipitation IRI model

Weight-based sparse coding for multi-shot person re-identification

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Science China(Information Sciences) 2015年第10期58卷 38-52页

作者： ZHENG YanWei SHENG Hao zhang beichen zhang Jun XIONG zhang State Key Laboratory of Software Development Environment School of Computer Science and EngineeringBeihang University Shenzhen Key Laboratory of Data Vitalization Research Institute in ShenzhenBeihang University Department of Electrical Engineering and Computer Science University of Wisconsin-Milwaukee

Person re-identification(Re-ID) is the problem of matching a person from different cameras based on appearance. It has interesting algorithm challenges and extensive practical applications. This paper presents a weight-based sparse coding approach for person re-identification. First, three hypotheses are introduced to achieve a linear combination of images based on sparse coding. Then, we convert the person re-identification problem into an optimization problem with sparse constraints. To reduce the influence of abnormal residuals caused by occlusion and body variation, a weight-based sparse coding approach is proposed to achieve the optimal weights by the ordering statistics of square residuals iteratively. Experiments on various public datasets for different multi-shot modalities have shown good performance of the proposed approach compared with other state-of-the-art ones(more than 42% and 34% at rank-1 on CAVIAR4 REID and i-LIDS, respectively).

关键词： smart city person re-identification video surveillance multi-shot weight-based sparse coding

Observations of the step-like accelerating processes of cold ions in the reconnection layer at the dayside magnetopause

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Science Bulletin 2018年第1期63卷 31-37页

作者： Qinghe zhang Michael Lockwood John C.Foster Qiugang Zong Malcolm W.Dunlop Shunrong zhang Joran Moen beichen zhang Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China Department of Meteorology University of ReadingReading RG6 6BBUK MIT Haystack Observatory WestfordMA 01886USA School of Earth and Space Sciences Peking UniversityBeijing 100087China Space Sciences Division SSTDRutherford Appleton LaboratoryDidcot OX11 OQXUK Department of Physics University of OsloBlindern 0316OsloNorway SOA Key Laboratory for Polar Science Polar Research Institute of ChinaShanghai 200136China

Cold ions of plasmaspheric origin have been observed to abundantly appear in the magnetospheric side of the Earth's magnetopause. These cold ions could affect the magnetic reconnection processes at the magnetopause by changing the Alfvén velocity and the reconnection rate, while they could also be heated in the reconnection layer during the ongoing reconnections. We report in situ observations from a partially crossing of a reconnection layer near the subsolar magnetopause. During this crossing, step-like accelerating processes of the cold ions were clearly observed, suggesting that the inflow cold ions may be separately accelerated by the rotation discontinuity and slow shock inside the reconnection layer.

关键词： Cold ions Magnetic reconnection Ion accelerations Magnetopause

High power-efficient asynchronous SAR ADC for IoT devices

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Journal of Semiconductors 2017年第10期38卷 2-8页

作者： beichen zhang Bingbing Yao Liyuan Liu Jian Liu Nanjian Wu Institute of Semiconductors Chinese Academy of Sciences University of Chinese Academy of Sciences

This paper presents a power-efficient 100-MS/s,10-bit asynchronous successive approximation register（SAR） *** includes an on-chip reference buffer and the total power dissipation is 6.8 *** achieve high performance with high power-efficiency in the proposed ADC,bootstrapped switch,redundancy,set-and-down switching approach,dynamic comparator and dynamic logic techniques are *** prototype was fabricated using 65 nm standard CMOS *** a 1.2-V supply and 100 MS/s,the ADC achieves an SNDR of 56.2 dB and a SFDR of 65.1 *** ADC core consumes only 3.1 mW,resulting in a figure of merit（FOM） of 30.27 fJ/conversionstep and occupies an active area of only 0.009 mm^2.

关键词： SAR ADC asynchronous bootstrapped switch dynamic logic power efficiency

SuperDARN CUTLASS Finland radar observations of high-latitude magnetic reconnections under northward interplanetary magnetic field (IMF) conditions

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Science China(Technological Sciences) 2012年第5期55卷 1207-1216页

作者： zhang QingHe LIU RuiYuan YANG HuiGen HU HongQiao zhang beichen DUNLOP Malcolm LESTER Mark BOGDANOVA Yulia WALSH Andrew SOA Key Laboratoryfor Polar Science Polar Research Institute of ChinaShanghai 200136China Space Science Department Rutherford-Appleton LaboratoryChiltonDidcotUK Department of Physics and Astronomy University of LeicesterLeicesterUK Mullard Space Science Laboratory University College LondonDorkingSurreyUK

A number of backscatter power enhancement events with ＂equatorward-moving radar auroral forms＂ in the high-latitude ionosphere were observed by SuperDARN CUTLASS Finland radar when the IMF was northward during 09：00 -10：00 UT on 26 March 2004. These events were also associated with sunward flow enhancements at each location in the Northern Hemisphere which were shown in ionospheric convections measured by the SuperDARN radars. These are typical features of high-latitude （lobe） magnetic reconnections. The durations of the velocity enhancements imply that the evolution time of the lobe reconnec- tions is about 8-16 rain from their origin at the reconnection site to their addition to the magnetotall lobe again. In additional, the Double Star TC-1 spacecraft was moving from magnetosheath into magnetosphere, and crossing the magnetopause near the subsolar region during this interval, and observed typical low-latitude magnetic reconnection signatures. This infers that the dayside high- and low-latitude reconnections may occur simultaneously.

关键词： high-latitude magnetic reconnection equatorward-moving radar auroral form evolution time of the lobe reconnections

Application of autocorrelation method on ionospheric short--term forecasting in China

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Chinese Science Bulletin 2006年第3期51卷 352-357页

作者： LIU Ruiyuan LIU Shunlin XU Zhonghua WU Jian WANG Xianyi zhang beichen HU Hongqiao School of Electronic Information of Wuhan University Wuhan 430072 China Polar Research Institute of China Shanghai 200136 China China Research Institute of Radiowave Propagation Xinxiang 453003 China

Adopting the autocorrelation method in the ionospheric short-term forecasting, we put for- ward a simple and practical forecasting method― the sectional autocorrelation method, that is, for pre- dictions of one hour to four hours ahead the auto- correlation coefficient of RDF with the “iteration” method is selected, for prediction of more than four hours ahead, the autocorrelation coefficient of f0F2 with the “at once” method is used. The prediction precisions have been quantitatively estimated based on the data from Chongqing and Guangzhou Ionos- onde Stations. It is shown that the method is much improved for the predictions of one hour to four hours ahead. For the predictions of more than four hours ahead the prediction error reaches a saturation value, which is still lower than that of the “median” method. This new method could also be applied to the short-term forecasting of other ionospheric parame- ters.

关键词：电离层电离层预报自相关法短期预报中国

A conjugate study of the polar ionospheric F2-layer and IRI-2007 at 75 ° magnetic latitude for solar minimum

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Advances in Polar Science 2011年第3期22卷 175-183页

作者： HE Fang zhang beichen JoranMoen HUANG DeHong SOA Key Laboratory for Polar Science Polar Research Institute of China Shanghai 200136 China Department of Physics University of Oslo Norway

Long-duration conjugate observations by the EISCAT Svalbard Radar （ESR） and the ionosonde at Zhongshan station from the International Polar Year （IPY） during solar minimum conditions are analyzed, with respect to variability in the F2-1ayer peak parameters. A comparison between International Reference Ionosphere- 2007 （IRI-2007） and observation data clearly demonstrates good agreement in summer, but greater deviations in winter. The IRI model reproduces the F2 peak parameters dominated by solar photoionization reasonably well, but it does not address the effect of electron precipitation. Hence, the discrepancies become large in the winter auroral ionosphere.

关键词： Solar minimum polar ionosphere IRI electron precipitation

Statistical characteristics of ionospheric backscatter observed by SuperDARN Zhongshan radar in Antarctica

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Advances in Polar Science 2013年第1期24卷 19-31页

作者： HU Hongqiao LIU Erxiao LIU Ruiyuan YANG Huigen zhang beichen SOA Key Laboratory for Polar Science Polar Research Institute of China School of Science Xidian University

Zhongshan HF radar, as one component of SuperDARN, has been established and in operation since April, 2010. Using data from the first two years of its operation, this paper investigates the radar＇s performance, the diurnal and seasonal variations o1 ionospheric echoes, and their dependence on geomagnetic activity. Statistical studies show that the occurrence of echoes in different beams varies at different frequencies, which arises from the direction of the beam and the area over which the beam can achieve the orthogonality condition between the wave vector and the Earth＇s magnetic field. The diurnal variation is obvious with double peak structures both in the occurrence rate and average power at 04-08 UT and 16-17 UT. The line-of-sight velocities are mainly positive on the dayside and negative on the nightside for Beam 0, which is the opposite of the trend for Beam 15. The spec- tral widths on the dayside are often higher than those on the nightside owing to the high energy particle precipitation in the cusp region. The seasonal variations are more obvious for those beams with larger numbers. The occurrence, the average power, the line-of-sight velocity, and the spectral widths are generally larger in the winter months than in the summer months. The influence of geomagnetic activity on radar echoes is significant. The peak echo occurrence appears on the dayside during geomagnetically quiet times, and shifts toward the nightside and exhibits an obvious decrease with increasing Kp. With increasing geomagnetic activity, the line-of-sight velocities increase, whereas the spectral widths decrease. The frequency dependence is investigated and it is found that in the operating frequency bands in 2010, 9-10 MHz is the most appropriate band for the SuperDARN Zhongshan radar.

关键词： SuperDARN Zhongshan radar diurnal variations seasonal variations geomagnetic activity dependence frequency dependence

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中国第40次南极科学考察简报

极地研究 2024年第3期36卷 496-497页

作者：张北辰中国极地研究中心(中国极地研究所) 上海200129

2023/2024年度实施的中国第40次南极科学考察围绕南极重点海域对气候变化的响应和影响等重大科学问题,执行“五海五站”科学考察任务。考察队暨“雪龙”号、“雪龙2”号考察船于2023年11月1日从上海出发,2024年4月上旬返回国内。考察队... 详细信息

2023/2024年度实施的中国第40次南极科学考察围绕南极重点海域对气候变化的响应和影响等重大科学问题,执行“五海五站”科学考察任务。考察队暨“雪龙”号、“雪龙2”号考察船于2023年11月1日从上海出发,2024年4月上旬返回国内。考察队下设15个站、船、队,由来自80余家单位的460余人组成。

关键词：南极科学考察重大科学问题考察队

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中国第34次南极科学考察简报

极地研究 2018年第4期30卷 447-449页

作者：张北辰不详

中国第34次南极科学考察始于2017年11月8日,至2018年4月21日结束,历时165天。本次考察由257名队员组成,包括来自美国、加拿大、新西兰、俄罗斯、泰国的12名队员,其中科考人员114名。本次考察的航行及调查航行日程如下:2017年11月8日—2... 详细信息

中国第34次南极科学考察始于2017年11月8日,至2018年4月21日结束,历时165天。本次考察由257名队员组成,包括来自美国、加拿大、新西兰、俄罗斯、泰国的12名队员,其中科考人员114名。本次考察的航行及调查航行日程如下:2017年11月8日—2018年11月26日,从上海至基督城;2017年11月26日—2017年11月28日,靠港在基督城;2017年11月28日—2017年12月9日,从基督城至罗斯海;2017年12月9日.2017年12月14日,在罗斯海作业;2017年12月14日_-2017年12月29日,从罗斯海至中山站:2017年12月29日_2018年1月10日,在中山站作业;2018年1月10日_2018年1月15日,从中山站至普里兹湾作业;2018年1月15日—2018年1月17日,从普里兹湾至戴维斯海;2018年1月17日—2018年1月22日,在戴维斯海作业;2018年1月22日—2018年2月2日,从戴维斯海至罗斯海;2018年2月2日—’2018年2月12日,在罗斯海作业;2018年2月12日—2018年2月21日,从罗斯海至基督城;2018年2月21日—2018年2月23日,靠港在基督城;2018年2月23日.2018年3月2日,从基督城至阿蒙森海;2018年3月2日—2018年3月23日,在阿蒙森海作业;2018年3月23日—2018年4月21日,阿蒙森海至上海。

关键词：科学考察南极中国普里兹湾罗斯海中山站戴维斯作业