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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 ${\bm~{Einstein~~Probe}}$

对数动态骨架本构模型的多维实现及其在ABAQUS中的应用

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岩土工程学报 2025年第1期47卷 192-199页

作者：董青陈苏李小军董云陈亚东周正华朱俊淮阴工学院建筑工程学院江苏淮安223003 北京工业大学城建学部北京100124 南京工业大学交通运输工程学院江苏南京210009

对数动态骨架本构以对数函数作为骨架曲线,引入“修正动骨架曲线”和“阻尼比退化系数”的概念,考虑试验阻尼对滞回曲线的影响,实现试验阻尼和滞回阻尼在数学上自洽的非线性动力本构。该本构只适用于一维土层场地时域非线性地震反应分... 详细信息

对数动态骨架本构以对数函数作为骨架曲线,引入“修正动骨架曲线”和“阻尼比退化系数”的概念,考虑试验阻尼对滞回曲线的影响,实现试验阻尼和滞回阻尼在数学上自洽的非线性动力本构。该本构只适用于一维土层场地时域非线性地震反应分析。基于对数动态骨架本构函数关系式,给出对数动态骨架参数的求解方法,并推导出加卸载曲线的时变切线剪切模量。通过ABAQUS软件的操作平台和等效剪应变算法,开发了基于对数动态骨架本构模型的显式子程序模块,该模型适用于二维和三维土层场地非线性地震反应分析。选取含软弱淤泥质土层场地作为计算模型,将从基岩输入不同加速度峰值的EI centro地震动的数值模拟结果进行对比,验证可考虑土体阻尼效应的对数动态骨架本构以及开发子程序的合理性和可用性。

关键词：对数动骨架本构阻尼比场地地震反应时变切线剪切模量

MmWave Beamforming for UAV Communications with Unstable Beam Pointing

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China Communications 2019年第1期16卷 37-46页

作者： Weizhi zhong Lei Xu Qiuming zhu Xiaomin chen Jianjiang Zhou College of Astronautics Nanjing University of Aeronautics and Astronautics College of Electronic and Information Engineering Nanjing University of Aeronautics and Astronautics

Millimeter wave(mmWave) communications of unmanned aerial vehicles(UAVs) have drawn dramatic attentions for its flexibility on a variety of ***,channel tracking base on the spatial features has been proposed to solve the problem of beam misalignments due to the UAV ***,unstable beam pointing caused by the non-ideal beam tracking environment may impact the performance of mmWave systems *** this paper,an improved beamforming method is presented to overcome this ***,the effect of the beam deviation is analyzed through the establishment of the equivalent data ***,combining the quantification of spatial angle and the improved orthogonal matching pursuit(OMP) algorithm,an optimized beam corresponding to the beam deviation is *** results show that the optimized beam of the proposed approach can effectively improve the spectral efficiency without improving the complexity when the beam pointing is unstable.

关键词： UAV communications mmWave beamforming unstable beam pointing beam tracking orthogonal matching pursuit(OMP)

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太湖底泥磷释放量及释放规律的研究综述

湖泊科学 2025年第1期37卷 14-35页

作者：朱伟侯豪刘环许小格朱瑜星陈诺曹俊林乃喜河海大学环境学院南京210098 河海大学土木与交通学院南京210098 河海大学水科学研究院南京210098

太湖是我国最为重要的湖泊之一,是国家湖泊治理的重点。自2007年水危机以来,太湖治理累计投入超2620亿元,是世界上治理力度最大的湖泊。2016年以来太湖出现磷反弹,2020年开始显著好转,2023年水华减少。太湖蓝藻水华与磷的响应相对显著,... 详细信息

太湖是我国最为重要的湖泊之一,是国家湖泊治理的重点。自2007年水危机以来,太湖治理累计投入超2620亿元,是世界上治理力度最大的湖泊。2016年以来太湖出现磷反弹,2020年开始显著好转,2023年水华减少。太湖蓝藻水华与磷的响应相对显著,回顾太湖磷十余年来的研究,关于底泥内源释放对水体总磷贡献的说法不一,这对于太湖整体磷负荷的认识及内源治理措施的制定产生了重要影响。针对太湖底泥磷的源汇、释放量以及释放规律,本文对国内外关于湖泊底泥磷释放的监测、实验、计算等研究进行系统回顾,对关于太湖底泥释放方面的研究进行梳理。通过比较和分析,尝试形成对太湖底泥磷释放规律和范围的一些基本认识。通过综述总结提出了“总源”“总汇”“净源”“净汇”的概念,并对可能成为“净源”的5个过程的发生条件和释放强度进行分析。认为Fick扩散释放是可以恒常性发生的过程,而在具备条件才发生的过程中,DO<2 mg/L后出现的磷还原释放是比较主要的过程,需要重点关注。“净源”是否发生应该依据实际湖泊的环境条件开展动态释放实验来判断。太湖目前虽然处于“总汇”状态,但“净源”是显著存在的,明确“净源”存在的位置和发生的时段对于太湖内源治理非常重要。

关键词：太湖底泥磷释放源汇质量平衡释放实验

Ground fissure development regularity and formation mechanism of shallow buried coal seam mining with Karst landform in Jiaozi coal mine: a case study

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Journal of Mountain Science 2023年第10期20卷 3101-3120页

作者： zhu Heng-zhong School of Energy and Mining Engineering Shandong University of Science and TechnologyQingdao 26659oChina State Key Laboratory of Strata Intelligent Control and Green Mining Co-Founded by Shandong Province and the Ministry of Science and Technology Shandong University of Science and TechnologyQingdao 266590China State Key Laboratory of Water Resource Protection and Utilization in Coal Mining Beijing 102209China

A comprehensive study was undertaken at Jiaozi coal mine to investigate the development regularity of ground fissures in shallow buried coal seam mining with Karst landform,shedding light on the development type,geographical distribution,dynamic development process,and failure mechanism of these ground fissures by employing field monitoring,numerical simulation,and theoretical *** findings demonstrate that ground fissure development has an obvious feature of subregion,and its geographical distribution is significantly affected by *** type,open type,and stepped type are three different categories of ground *** fissures emerge dynamically as the panel advances,and they typically develop with a distance of less than periodic weighting step distance in advance of panel advancing *** fissures present the dynamic development feature,temporary fissure has the ability of *** dynamic development process of ground fissure with closed-distance coal seam repeated mining is expounded,and the development scale is a dynamic development stage of“closure→expansion→stabilized”on the basis of the original development *** the perspective of topsoil deformation,the computation model considering two points movement vectors towards two directions of the gob and the ground surface is established,the development criterion considering the critical deformation value of topsoil is *** mechanical model of hinged structure of inclined body is proposed to clarify the ground fissure development,and the interaction between slope activity and ground fissure development is *** research results fulfill the gap of ground fissures about development regularity and formation mechanism,and can contribute to ground fissure prevention and treatment with Karst landform.

关键词： Karst landform Shallow buried coal seam Development regularity Formation mechanism Ground fissure Repeated mining

Study on the Characteristics of A New Hybrid Mooring System for DualPlatform Joint Operations

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China Ocean Engineering 2023年第3期37卷 506-518页

作者： SHEN zhong-xiang YUAN Zhao-jun LI Hong-bin zhu chen-yang School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China College of Harbor Coastal and Offshore EngineeringHohai UniversityNanjing 210098China Nantong COSCO KHI Ship Engineering Co.Ltd Nantong 226005China

As the sustainable exploitation of marine resources develops,dual-platform joint operation has caught increasing ***-platform joint operation requires smaller relative motion between the two sub-platforms,which is normally difficult to be satisfied by the traditional mooring ***,a new hybrid mooring system is developed and studied in this *** ensure safety during platform movements,both the number of anchor chains and the relative motion between the two sub-platforms are reduced in the new hybrid mooring *** performing numerical simulations based on three-dimensional potential flow theory in AQWA and physical experiments,the performances of both the new hybrid and traditional mooring systems under two different wave conditions(i.e.,working wave and freak wave conditions) are systematically *** the new hybrid mooring system,the relative stability between the two sub-platforms of the new system is better,and the platforms can restore stability faster when affected by freak waves.

关键词： dual-platform joint operation platform relative stability hybrid mooring system freak wave

Exploring metro vibrancy and its relationship with built environment:a cross-city comparison using multi-source urban data

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Geo-Spatial Information Science 2022年第2期25卷 182-196页

作者： Wei Tu Tingting zhu chen zhong Xiaohu Zhang Yang Xu Qingquan Li Guangdong Key Laboratory of Urban Informatics and Shenzhen Key Laboratory of Spatial Smart Sensing and ServiceSchool of Architecture and Urban PlanningShenzhen UniversityShenzhenChina Ministry of Natural Resources(MNR)Key Laboratory for Geo-Environmental Monitoring of Great Bay Area Shenzhen UniversityShenzhenChina The Bartlett Centre for Advanced Spatial Analysis(CASA) University College London(UCL)LondonUK Department of Urban Planning and Design The University of Hong KongHong KongChina Department of Land Surveying and Geo-Informatics The Hong Kong Polytechnic UniversityHong Kong SARChina

Recent urban transformations have led to critical reflections on the blighted urban infrastruc-tures and called for re-stimulating vital urban ***,the metro has been recognized as the backbone infrastructure for urban mobility and the associated economy *** date,limited research has been devoted to investigating the relationship between metro vitality and built environment in mega-cities *** paper presents a multisource urban data-driven approach to quantify the metro vibrancy and its association with the underlying built *** smart card data is processed to extract metro ridership,which denotes the vibrancy around the metro station in physical *** media check-ins are crawled to measure the vitality of metros in virtual *** physical and virtual vibrancy are integrated into a holistic metro vibrancy metric using an entropy-based weighting *** built environment characteristics,including land use,transportation and buildings are modeled as independent *** significant influences of built environ-mental factors on the metro vibrancy are unraveled using the ordinary least square regression and the spatial lag *** experiments conducted in Shenzhen,Singapore and London,this study comes up with a conclusion that spatial distributions of metro vibrancy metrics in three cities are spatially *** regression analysis suggests that in all the three cities,more affluent urban areas tend to have higher metro virbrancy,while the road density,land use and buildings tend to impact metro vibrancy in only one or two *** results demonstrate the relationship between the metro vibrancy and built environment is affected by complex urban *** findings help us to understand metro vibrancy thus make proper policy to re-stimulate the important metro infrastructure in the future.

关键词： Urban vibrancy spatial-autocorrelation spatial lag model smart card data social media

Water boosted CO_(2)/C_(2)H_(2)separation in L-arginine functionalized metal–organic framework

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Nano Research 2023年第5期16卷 6113-6119页

作者： Hejin zhu Wenjuan Xue Hongliang Huang Lvyun chen Haoyu Liu Chongli zhong State Key Laboratory of Separation Membranes and Membrane Processes Tiangong UniversityTianjin 300387China Country School of Chemistry and Chemical Engineering Tiangong UniversityTianjin 300387China School of Material Science and Engineering Tiangong UniversityTianjin 300387China

The separation of CO_(2)/C_(2)H_(2)mixture by CO_(2)-selective sorbents is an energy-efficient C_(2)H_(2)purification technique,but is strategically challenging due to their similar molecular size and physicochemical ***,water is inevitable in CO_(2)/C_(2)H_(2)mixture and it is usually a significant barrier because of its competitive adsorption with CO_(2).To address this challenge,herein,we report the first example of metal–organic framework(MOF)that exhibits water-boosted CO_(2)adsorption and CO_(2)/C_(2)H_(2)separation by anchoring L-arginine(ARG)on the Zr6 cluster of *** CO_(2)affinity and capacity in the resulting MOF-808-ARG are markedly facilitated by the presence of water,while the C_(2)H_(2)adsorption is significantly ***,CO_(2)adsorption capacities in adsorption isotherm and breakthrough measurement are increased to 143%and 184%,*** addition,the wet MOF-808-ARG exhibits the record CO_(2)/C_(2)H_(2)selectivity of 1,180 under zero *** experiments reveal that CO_(2)/C_(2)H_(2)mixture can be completely separated and the result of mass spectrometry indicates that the C_(2)H_(2)purity in the outlet is up to 99.9%.In situ infrared(IR)results and density functional theory(DFT)calculations reveal the water-promoted CO_(2)adsorption mechanism that the formation of bicarbonate products in the presence of water is thermodynamically and kinetically more favorable than that without ***,MOF-808-ARG also possesses excellent water stability and excellent regeneration of CO_(2)*** work provides a new paradigm by transforming the negative effects of water into positive ones for CO_(2)/C_(2)H_(2)separation.

关键词： metal–organic frameworks L-arginine moisture acetylene(C_(2)H_(2))purification CO_(2)adsorption

Research on the "three shells" cooperative support technology of large-section chambers in deep mines

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International Journal of Mining Science and Technology 2021年第4期31卷 665-680页

作者： cheng zhu Yong Yuan Wenmiao Wang zhongshun chen Shengzhi Wang Huiwei zhong Key Laboratory of Deep Coal Resources Mining Ministry of Education of ChinaChina University of Mining and TechnologyXuzhou 221116China School of Mines State Key Laboratory of Coal Resources&Safe MiningChina University of Mining and TechnologyXuzhou 221116China

The"three shells"cooperative support technology was proposed herein according to both the large deformation of the rock surrounding large-section chambers in deep mines and the precarious stability of the support structures *** development range of the plastic zone in the surrounding rock was controlled by a stress shell to reduce the difficulty of controlling the surrounding ***,the residual strength of the rock mass in the plastic zone and the self-bearing capacity of the surrounding rock were improved by a reinforced load-bearing ***,a passive load-bearing shell could restore the triaxial stress state of the surrounding rock on the free surface,reduce the influence of the external environment on the surrounding rock,and reinforce the surrounding rock with the strength of the *** layouts of large-section chambers were determined by analyzing the control effect of the stress shell on the surrounding rock under three kinds of in situ stress *** orthogonal test method was applied to reveal the influences of different support parameters in the reinforced loadbearing shell and passive load-bearing shell on the surrounding rock *** surrounding rock control effect of the"three shells"collaborative support technology was analyzed through numerical simulation and field *** results show that the maximum displacement between the roof and floor of the coal preparation chamber in the Xinjulong coal mine was approximately 48 mm,and the maximum displacement between its two sides was approximately 65 mm,indicating that the technology proposed herein could meet the long-term control requirements of the surrounding rock stability for large-section chambers in deep mines.

关键词： Deep mining Large-section chamber "Three shells"cooperative support Reasonable layout Surrounding rock control