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Einstein Probe discovery of EP240408a: A peculiar X-ray transient with an intermediate timescale

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Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 222-240页

作者： Wenda zhang Weimin Yuan Zhixing Ling Yong Chen Nanda Rea Arne Rau Zhiming Cai huaqing Cheng Francesco Coti Zelati Lixin Dai Jingwei Hu Shumei jia Chichuan Jin Dongyue Li Paul O’Brien Rongfeng Shen Xinwen Shu Shengli Sun Xiaojin Sun Xiaofeng Wang Lei yang Bing zhang Chen zhang Shuang-Nan zhang Yonghe zhang Jie An David Buckley Alexis Coleiro Bertrand Cordier Liming Dou Rob Eyles-Ferris Zhou Fan hua Feng Shaoyu Fu Johan P.U.Fynbo Lluis Galbany Saurabh W.Jha Shuaiqing jiang Albert Kong Erik Kuulkers Weihua Lei Wenxiong Li Bifang Liu Mingjun Liu Xing Liu Yuan Liu Zhu Liu Chandreyee Maitra Alessio Marino Itumeleng Monageng Kirpal Nandra Jeremy Sanders Roberto Soria Lian Tao Junfeng Wang Song Wang Tinggui Wang Zhongxiang Wang Qingwen Wu Xuefeng Wu Dong Xu yanjun Xu Suijian Xue Yongquan Xue Zijian zhang Zipei Zhu Hu Zou Congying bao Fansheng Chen Houlei Chen Tianxiang Chen Wei Chen Yehai Chen Yifan Chen Chenzhou Cui Weiwei Cui yanfeng Dai Dongwei Fan Ju Guan Dawei Han Dongjie Hou Haibo Hu Maohai huang jia Huo Zhenqing jia Bowen jiang Ge Jin Chengkui Li Junfei Li Longhui Li Maoshun Li Wei Li Zhengda Li Tianying Lian Congzhan Liu Heyang Liu huaqiu Liu Fangjun Lu Laidan Luo jia Ma Xuan Mao Haiwu Pan Xin Pan Liming Song Hui Sun Yunyin Tan Qingjun Tang Yihan Tao Hao Wang Juan Wang Lei Wang Wenxin Wang Yilong Wang Yusa Wang Qinyu Wu Haitao Xu Jingjing Xu Xinpeng Xu Yunfei Xu zhao Xu Changbin Xue Yulong Xue Ailiang yan Haonan yang Xiongtao yang yanji yang Juan zhang Mo zhang Wenjie zhang Zhen zhang Zhen zhang Ziliang zhang Donghua zhao Haisheng zhao Xiaofan zhao Zijian zhao Hongyan Zhou Yilin Zhou Yuxuan Zhu Zhencai Zhu National Astronomical Observatories Chinese Academy of Sciences School of Astronomy and Space Sciences University of Chinese Academy of Sciences Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Institute of Space Sciences (ICE) CSIC Institut d’Estudis Espacials de Catalunya (IEEC) Max Planck Institute for Extraterrestrial Physics Innovation Academy for Microsatellites Chinese Academy of Sciences Department of Physics University of Hong Kong School of Physics and Astronomy University of Leicester School of Physics and Astronomy Sun Yat-sen University Department of Physics Anhui Normal University Shanghai Institute of Technical Physics Chinese Academy of Sciences Physics Department Tsinghua University Nevada Center for Astrophysics University of Nevada Las Vegas Department of Physics and Astronomy University of Nevada Las Vegas South African Astronomical Observatory Department of Astronomy University of Cape Town Department of Physics University of the Free State Université Paris Cité CNRS Astroparticule et Cosmologie Université Paris Cité CEA Paris-Saclay IRFU/DAp-AIM Department of Astronomy Guangzhou University Cosmic Dawn Center (DAWN) Niels Bohr Institute University of Copenhagen Department of Physics and Astronomy Rutgers the State University of New Jersey Institute for Cosmic Ray Research The University of Tokyo ESA/ESTEC Department of Astronomy School of Physics huazhong University of Science and Technology INAF-Osservatorio Astrofisico di Torino Sydney Institute for Astronomy School of Physics The University of Sydney Department of Astronomy Xiamen University Institute for Frontiers in Astronomy and Astrophysics Beijing Normal University Department of Astronomy University of Science and Technology School of Astronomy and Space Sciences University of Science and Technology of China Institute of Deep Space Sciences Deep Space Exploration Laboratory Department of Astronomy School of Physics and Astronomy Yunnan University Shanghai Astronomical Observatory Chi

We report the discovery of a peculiar X-ray transient,EP240408a,by Einstein Probe （EP） and follow-up studies made with EP,Swift,NICER,GROND,ATCA and other ground-based multiwavelength *** new transient was first detected with Wide-field X-ray Telescope （WXT） on board EP on April 8th,2024,manifested in an intense yet brief X-ray flare lasting for *** flare reached a peak flux of 3.9×10-9erg cm-2s-1in 0.5-4 ke V,～300 times brighter than the underlying X-ray emission detected throughout the *** and more precise follow-up observations by EP/FXT,Swift and NICER confirmed the finding of this new *** X-ray spectrum is non-thermal in 0.5-10 ke V,with a power-law photon index varying *** X-ray light curve shows a plateau lasting for ～4 d,followed by a steep decay till becoming undetectable ～10 d after the initial *** on its temporal property and constraints from previous EP observations,an unusual timescale in the range of 7-23 d is found for EP240408a,which is intermediate between the commonly found fast and long-term *** counterparts have been found in optical and near-infrared,with the earliest observation at 17 h after the initial X-ray detection,suggestive of intrinsically weak emission in these *** demonstrate that the remarkable properties of EP240408a are inconsistent with any of the transient types known so far,by comparison with,in particular,jetted tidal disruption events,gamma-ray bursts,X-ray binaries and fast blue optical *** nature of EP240408a thus remains an *** suggest that EP240408a may represent a new type of transients with intermediate timescales of the order of～10 *** detection and follow-ups of more of such objects are essential for revealing their origin.

关键词： X-ray transients ${\bm~{Einstein~~Probe}}$

Big Data Modeling and Analysis of Microblog Ecosystem

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International Journal of Automation and computing 2014年第2期11卷 119-127页

作者： hua-Ping zhang Rui-Qi zhang yan-Ping zhao bao-Jun Ma School of Computer Science Beijing Institute of Technology School of Management and Economics Beijing Institute of Technology School of Economics and Management Beijing University of Posts and Telecommunications

Recent progress of Web 2.0 applications has witnessed the rapid development of microblog in China, which has already been one of the most important ways for online communications, especially on sharing information. This paper tries to make an in-depth investigation on the big data modeling and analysis of microblog ecosystem in China by using a real dataset containing over17 million records of SinaWeibo users. First, we present the detailed geography, gender, authentication, education and age analysis of microblog users in this dataset. Then we conduct the numerical features distribution analysis, propose the user influence formula and calculate the influences for different kinds of microblog users. Finally, user content intention analysis is performed to reveal users most concerns in their daily life.

关键词： Microblog mining user activity pattern user personalization user intention microblog ecosystem.

Facile Preparation of Electromagnetic Interference Shielding Materials Enabled by Constructing Interconnected Network of Multi-walled Carbon Nanotubes in a Miscible Polymeric Blend

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Chinese Journal of Polymer Science 2020年第6期38卷 593-598页

作者： Qi-yan zhang Han-Song Li bao-hua Guo zhao-Xia Guo jian Yu Key Laboratory of Advanced Materials(Ministry of Education) Department of Chemical EngineeringTsinghua UniversityBeijing 100084China

Electromagnetic interference(EMI)shielding materials are in great demand in electronic equipment and our surrounding environment to resist the increasing serious radiation *** with their metal counterparts,conductive polymer composites(CPCs)have unique advantages of lightweight,corrosive resistance,low cost,and excellent processability,and are therefore an ideal choice for developing high-performance EMI shielding ***,CPCs based EMI shielding materials are limited to high filler loading,which caused poor mechanical properties and ***,we demonstrate a facile and highly scalable approach to develop high-performance EMI shielding materials with low filler loading by using miscible poly(phenylene oxide)/polystyrene(PPO/PS)blend as the *** contrast to PS/carbon nanotubes(CNTs)composites,PPO/PS/CNTs composites show much higher EMI shielding effectiveness caused by good dispersion of CNTs and highly interconnected conductive *** excellent EMI shieling effectiveness of 23-25 dB is achieved for PPO/PS/10%CNTs composites with a thickness of only 375 pm;which is superior to most of reported polymer/CNTs composites prepared by *** addition,the results show that although absorption is the major shielding mechanism,the contribution of reflection is also important and closely related to the connectivity of conductive network,as well as the electrical conductivity of the CPCs.

关键词： Conductive polymer composites Polymer blend Electromagnetic interference shielding Conductive network Dispersion

Effects of water discharge on river-dominated delta growth

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Petroleum Science 2021年第6期18卷 1630-1649页

作者： yan-bao zhang Yi-Ke Liu jia Yi Xue-jian Liu Institute of Geophysics China Earthquake AdministrationBeijing100081China Key Laboratory of Petroleum Resources Research Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China China Earthquake Disaster Prevention Center China Earthquake AdministrationBeijing100029China The Pennsylvania State University Department of GeosciencesUniversity ParkPA16802USA

River-dominated deltas are commonly developed at modern bays and lakes and ancient petroliferous *** discharge is an important variable at pay zone scales in river-dominated delta reservoirs,which affects deltaic sand distributions and ***,it's unclear how it influences riverdominated delta *** paper integrates Delft3 D simulations and modern analogs to analyze the effects of water discharge,considering growth time,sediment supply,and coupled effects of sediment *** water discharges lead to the formation of lobate deltas,and the water discharge of 1,000 m~3/s is a referenced threshold ***-grained,highly-cohesive sediments increase the threshold values of water discharge at which the deltas become lobate from digitate,and vice *** the same simulation time,high water discharges favor more rugose shorelines,more distributary channels(especially secondary distributaries),and longer and wider deltas with more land ***,for the same sediment supply,high water discharges have few effects on shoreline roughness and the number of distributary channels.

关键词： River-dominated delta Water discharge Morphology Distributary channel Hydrocarbon exploration

First-order multiples imaging aided by water bottom

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Petroleum Science 2021年第6期18卷 1650-1661页

作者： Zhen-hua Xu Sheng-He Wu Ming-Cheng Liu Jun-Shou zhao zhao-Hui Chen Ke zhang jia-jia zhang zhao Liu State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum-BeijingBeijing 102249China College of Geosciences China University of Petroleum-BeijingBeijing102249China Bohai Petroleum Research Institute CNOOC Tianjin BranchTianjin300459China Sinopec Geophysical Research Institute NanjingJiangsu211103China

Surface-related multiples frequently propagate into the subsurface and contain abundant information on small reflection *** with the conventional migration of primaries,migration of multiples offers complementary illumination and a higher vertical ***,crosstalk artifacts caused by unrelated multiples during reverse time migration(RTM)using multiples severely degrade the reliability and interpretation of the final migration ***,we proposed RTM using first-order receiver-side water-bottom-related multiples for eliminating crosstalk artifacts and enhancing vertical *** first backward propagate the first-order receiver-side water-bottom-related multiples using a water-layer model,followed by saving the upper boundary *** we produce the source wavefield using a seismic wavelet and the receiver wavefield by back-extrapolating the saved ***,the cross-correlation imaging condition is applied to generate the final *** method transforms the receiver-side multiples into primaries,followed by the conventional migration processing *** examples using synthetic datasets demonstrate that our method significantly enhances the imaging quality by eliminating crosstalk artifacts and improving the resolution.

关键词： Surface-related multiples Multiples imaging Multiples elimination

The Grey Analysis, Kriging and Selection Index of Flower Yield in Rugosa Rose

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Agricultural Sciences in China 2007年第12期6卷 1420-1425页

作者： LI yan-yan FENG Zhen zhao Lan-yong MO Zhen-hua zhang bao College of Forestry Shandong Agricultural University Tai＇an 271018 P. R. China

The analysis of grey system, kriging interpolation, and integration selection index were employed to investigate the relationships between the flower yield/plant （FY） and 15 other quantitative traits of 20 rugosa rose cultivars. The result showed that： The grey relational grade （GRG） of the number of flowers/plant （NF）, the number of branches/plant （NB）, the width of floral bud （WB）, and the weight/flower （WF） to the FY were larger （〉 0.5）; FY improved with the increase of NF and NB. Moreover, the indirect selection of either trait could not achieve improvement of FY. It is necessary to improve FY by multi-trait selection. The integration selection index （ISI） equation of FY was established with the characters NF, NB, WB, and WF： I= 0.3187x1 - 318.6x2 ＋ 670.1 x4 ＋ 6.3xa, index heritability = 0.8014, selective response of the integration breeding value = 245.8811. This will provide a theoretic basis for the genetic breeding of rugosa rose.

关键词： rugosa rose grey relational grade quantitative traits kriging interpolation index selection

Research progress on refractory composition and deformability of shell molds for TiAl alloy castings

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China Foundry 2018年第1期15卷 1-10页

作者： Chun-ling bao Shuang-qi zhang Yu-yan Ren You-wei zhang hua-sheng Xie Jun zhao Titanium Alloy Division Shenyang Research Institute of Foundry School of Materials Science and Engineering Shenyang University of Technology

At present, most TiAl components are produced by an investment casting process. Environmental and economic pressures have, however, resulted in a need for the industry to improve the current casting quality, reduce manufacturing costs and explore new markets for the process. Currently, the main problems for investment casting of TiAl alloys are cracks, porosities, and surface defects. To solve these problems, many studies have been conducted around the world, and it is found that casting defects can be reduced by improving composition and properties of the shell molds. It is important to make a summary for the related research progress for quality improvement of TiAl castings. So, the development on refractory composition of shell molds for TiAl alloy investment castings was reviewed, and research progress on deformability of shell mold for TiAl alloy castings both at home and abroad in recent years was introduced. The existing methods for deformability characterization and methods for improving the deformability of shell molds were summarized and discussed. The updated advancement in numerical simulation of TiAl alloy investment casting was presented, showing the necessity for considering the deformability of shell mold during simulation. Finally, possible research points for future studies on deformability of shell mold for TiAl alloy investment casting were proposed.

关键词： TiAl based alloys investment casting shell mold deformability

Lewis Acid Enables Ketone Phosphorylation:Synthesis of Alkenyl Phosphonates

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Chinese Journal of Chemistry 2021年第7期39卷 1855-1860页

作者： Xiao-Hong Wei Chun-Yuan bai Lian-Biao zhao Ping zhang Zhen-hua Li yan-Bin Wang Qiong Su Key Laboratory for Utility of Environment-Friendly Composite Materials and Biomass in University of Gansu Province College of Chemical EngineeringNorthwest Minzu UniversityNo.1Northwest XincunLanzhouGansu730030 China

Main observation and conclusion An efficient Lewis acid enabled ketones phosphonylation to synthesize vinylphosphonates has been *** method relays on ketone hydrophosphonylation/α-hydroxy phosphonates unimolecular el... 详细信息

关键词： Ketone Phosphorylation Alkenyl phosphonates Lewis acid Cascade reaction

Short-wavelength infrared InAs/GaSb superlattice hole avalanche photodiode

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Chinese Physics B 2020年第11期29卷 469-472页

作者： jia-Feng Liu ning-Tao zhang yan Teng Xiu-Jun Hao Yu zhao Ying Chen He Zhu Hong Zhu Qi-hua Wu Xin Li bai-Le Chen Yong huang School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China Key Laboratory of Nanodevices and Applications Suzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China School of Physical Science and Technology ShanghaiTech UniversityShanghai 201210China School of Information Science and Technology ShanghaiTech UniversityShanghai 201210China

We demonstrate two short-wavelength infrared avalanche photodiodes based on InAs/GaSb superlattice grown by metal-organic chemical vapor *** difference between the two devices,namely,p+n-n+and p+nn-n+,is that the p+nn-n+device possesses an additional middle-doped layer to separate the multiplication region from the absorption *** properly controlling the electric field distribution in the p+nn-n+device,an electric field of 906 kV/cm has been achieved,which is 2.6 times higher than that in the p+n-n+*** a reverse bias of-0.1 V at 77 K,both devices show a 100%cut-off wavelength of 2.25μ*** p+n-n+and p+nn-n+show a dark current density of 1.5×10^-7 A/cm^2 and 1.8×10^-8 A/cm^2,and a peak responsivity about 0.35 A/W and 0.40 A/W at 1.5μm,respectively.A maximum multiplication gain of 55 is achieved in the p+nn-n+device while the value is only less than 2 in the p+n-n+*** nature of the gain characteristic as a function of reverse bias confirms a single carrier hole dominated impact ionization.

关键词： short-wavelength infrared InAs/GaSb superlattice avalanche photodiodes metal-organic chemical vapor deposition