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

Burning rate analysis of laser controlled 5-aminotetrazole propellant

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Defence Technology（防务技术） 2023年第4期22卷 10-27页

作者： Nianbai He Ruiqi Shen Luigi T.DeLuca Lizhi Wu Wei Zhang Yinghua Ye School of Chemical Engineering Nanjing University of Science and Technology210094JiangsuChina Institute of space propulsion Nanjing University of Science and Technology210094JiangsuChina space propulsion Laboratory(Ret) Department of Aerospace Science and TechnologyPolitecnico di Milano20156MilanItaly

As an innovative propulsion technique, laser augmented chemical propulsion(LACP) seems superior to the traditional ones. However, the corresponding combustion theories have still to be ascertained for LACP. Burning rate of 5-aminotetrazole(5-ATZ) propellant has been studied by testing pressed samples under different combustor pressures and laser powers. Based on micro computed tomography(Micro CT),an advanced thickness-over-time(TOT) method to characterize the regression of the produced nonplanar burning surface is established. Because of a shell structure covering the combustion surface,the burning rate of the implemented 5-ATZ propellant is not constant during laser ablation. Resorting to functional fitting, a new law of non-constant burning including the effect of the observed unique burning surface structures is proposed. Accordingly, applicable combustion conditions of 5-ATZ based propellants have been preliminarily speculated for future research activities.

关键词： 5-Aminotetrazole(5-ATZ) Laser-augmented chemical propulsion(LACP) Non-constant burning rate Micro computed tomography(MicroCT) Non-planar burning surface

Hyper Heuristic Approach for Design and Optimization of Satellite Launch Vehicle

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Chinese Journal of Aeronautics 2011年第2期24卷 150-163页

作者： Amer Farhan RAFIQUE HE Linshu Ali KAMRAN Qasim ZEESHAN department of spacecraft Technology School of Astronautics Beihang University Beijing 100191 China department of space propulsion School of Astronautics Beihang University Beijing 100191 China

Satellite launch vehicle lies at the cross-road of multiple challenging technologies and its design and optimization present a typical example of multidisciplinary design and optimization（MDO） *** complexity of problem demands highly effi-cient and effective algorithm that can optimize the *** heuristic approach（HHA） based on meta-heuristics is applied to the optimization of air launched satellite launch vehicle（ASLV）.A non-learning random function（NLRF） is proposed to con-trol low-level meta-heuristics（LLMHs） that increases certainty of global solution,an essential ingredient required in product conceptual design phase of aerospace *** empirical study is performed to evaluate the performance advan-tages of proposed approach over popular non-gradient based optimization *** of ASLV encompasses aerodynamics,propulsion,structure,stages layout,mass distribution,and trajectory modules connected by multidisciplinary feasible design *** approach formulates explicit system-level goals and then forwards the design optimization process entirely over to *** distinctive approach for launch vehicle system design relieves engineers from tedious,iterative task and en-ables them to improve their component level *** is an impetus on vehicle performance and cost,and so it is considered as the core of vehicle design ***,gross launch mass is to be minimized in HHA.

关键词： multidisciplinary design optimization satellite launch vehicle heuristic optimization methods hyper heuristic air launched vehicles

Micro-impulse and plasma plume produced by irradiating aluminum target with nanosecond laser pulses in double-pulse scheme

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Plasma Science and Technology 2022年第7期24卷 82-89页

作者： Chenghao YU Jifei YE Weijing ZHOU Hao CHANG Wei GUO State Key Laboratory of Laser propulsion&Application Department of Aerospace and TechnologySpace Engineering UniversityBeijing 101416People's Republic of China

The micro-impulse generated by ablating an aluminum target in double-pulse laser bursts with different interpulse delays was investigated using a torsion *** plasma plume was simultaneously visualized using high-speed photography to analyze the coupling mechanism of the ablation *** experiment was carried out using a pulsed laser with a pulse width of 8 ns and a wavelength of 1064 *** experimental results show that an impulse with an interpulse delay of 60 ns is roughly 60%higher than that with no delay between the two pulses,when the energy of both laser pulses is 50 m ***,double-pulse schemes could enhance the ablation impulse under certain *** is because the ablation of the first laser pulse changes the optical properties of the aluminum target surface,increasing the ***,the ablation impulse is reduced with a time delay of 20 ns when the energy of both laser pulses is100 mJ or 150 *** can be concluded that the plasma produced by ablating the aluminum with the first pulse shields the second laser *** summarize,the experimental results show that different delay times in a double-pulse scheme have a significant effect on the ablation *** study provides a reference for the optimization of the parameters when laser ablation propulsion with a double-pulse scheme is applied in the fields of space debris removal,laser ablation thrusters,and so on.

关键词： laser ablation double pulse scheme impulse enhancement aluminum plasma plume fast photography

An efficient regulation approach for tomographic reconstruction in combustion diagnostics based on TDLAS method

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Chinese Journal of Aeronautics 2020年第12期33卷 3158-3166页

作者： Mingyuan XIN Junling SONG Wei RAO Yanji HONG Yajing JIANG State Key Laboratory of Laser propulsion&Application Space Engineering UniversityBeijing 101416China

For tomographic reconstruction in combustion diagnostics,it is usually necessary to solve a rank-deficient problem,where the number of non-linear dependent equations is smaller than the number of *** some reconstructions,there are grids without rays passing *** produces artifacts during the *** this paper,the weight of the regulation equation is modified with the number of the rays crossing the grid *** effect of the neighboring grid values as well as the number of rays crossing the grid cells is considered in the new regulation *** simulation results show that the new regulation method suppresses the reconstruction error of the no rays crossing grid and successfully restrains the corner distortion in four projection *** effects of the weight coefficient and the smoothing factor on the reconstruction are examined through a numerical ***,a combustion experiment demonstrates that the new regulation method can significantly reduce the reconstructed error,especially for the nonray crossing condition,and the results are compared with thermocouple measurements and reconstructions without modified regulation.

关键词： Absorption spectroscopy Combustion Number of rays Regulation function Tomographic reconstruction

Facile fabrication of CeO_2 hollow microspheres with yeast as bio-templates

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Journal of Rare Earths 2015年第12期33卷 1329-1334页

作者：牟广宇魏清莲黄永民 Key Laboratory of Specially Functional Polymeric Materials and Related Technology Ministry of Education department of Chemistry East China University of Science and Technology Shanghai Engineering Research Center of space Engine Shanghai Institute of space propulsion

CeO2 hollow microspheres were prepared through a facile method by using yeast cells as bio-templates. The yeast pro- vided a solid flame for the deposition of cerium hydroxide to form the hybrid Ce（OH）3@yeast precursor. The resulting CeO2 hollow microspheres were obtained by calcining the precursor. The products were characterized by field emission scanning electron micros- copy （FE-SEM）, transmission electron microscopy （TEM）, X-ray powder diffraction （XRD）, fourier transform infrared spectroscopy （FTIR）, N2 adsorption/desorption analysis, X-ray photoelectron spectrum （XPS） and H2 temperature programmed reduction （H2-TPR） It was found that the products fully retained the morphology of the yeast cells and the size of the hollow microspheres was about 1.5-2 μm. The catalytic test results showed that the as-obtained hollow CeO2 microspheres possessed a higher catalytic activity in CO oxidation than the commercial CeO2, which attributed to their higher surface area, hollow structure and superior reducibility. This study provided a promising route for the preparation of a variety of other inorganic hollow microspheres.

关键词： bio-template CeO2 hollow spheres CO oxidation rare earths

Burning surface formation mechanism of laser-controlled 5-aminotetrazole propellant

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Defence Technology（防务技术） 2023年第7期25卷 48-59页

作者： Nian-bai He Rui-qi Shen Luigi T.DeLuca Li-zhi Wu Wei Zhang Ying-hua Ye Yue-ting Wang School of Chemical Engineering Nanjing University of Science and Technology210094JiangsuChina Institute of space propulsion Nanjing University of Science and Technology210094JiangsuChina Sichuan Huachuan Industries Corporation 610106SichuanChina space propulsion Laboratory(Ret) Department of Aerospace Science and TechnologyPolitecnico di Milano20156MilanItaly

As an innovative propulsion technique, combustion mechanism of laser-augmented chemical propulsion has still to be ascertained. Benefiting from high nitrogen content and thermal stability, 5-aminotetrazole is a suitable ingredient for LACP. Under a flowing nitrogen environment, two kinds of unique burning surfaces were observed to occur for 5-ATZ, used as a single reacting propellant ingredient with the addition of carbon, under laser ablation. Both surfaces are hollow structures and differ by the possible presence of edges. Using micro computed tomography, the 3D perspective structures of both surfaces were revealed. Resorting to various characterization methods, a unified formation mechanism for both surfaces is proposed. This mechanism specifically applies to laser ablation, but could be crucial to common burning mechanisms in LACP.

关键词： 5-Aminotetrazole(5-ATZ) Laser-augmented chemical propulsion (LACP) Combustion mechanism Burning surface Micro computed tomography(MicroCT)

Power plant selection in a carbon constrained world the TERA(technoeconomic environmental risk analysis)

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航空动力学报 2009年第4期24卷 896-902页

作者： Stephen Ogaji Pericles Pilidis Vishal Sethi department of Power and propulsion School of Engineering Cranfield University

There is an increasing concern that current trends of consumption of natural resources cannot *** is imperative that major targeted investments are made into economical and reliable environment friendly propulsion and power *** novel and promising concepts are being *** selection of the best candidates to pursue for investment becomes a very difficult choice.A detailed TERA(techno-economic environmental risk analysis) framework is described here to quantify risks and to compare and rank competing schemes on a formal and consistent *** technique is based on detailed and rigorous thermodynamic representations of power plants.A layer of environment,economic,weather and other models to describe the appropriate local conditions is superimposed to *** outcome is a techno-economic environmental risk analysis framework with appropriate detail of each power plant as applied to the appropriate *** results for each concept can then be compared and contrasted to make appropriate selections.

关键词： TERA(techno-economic environmental risk analysis) techno-economic risk analysis gas turbine multi-disciplinary optimisation(MDO)

Optimization of magnetic field design for Hall thrusters based on a genetic algorithm

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Plasma Science and Technology 2024年第7期26卷 82-92页

作者：谭睿杭观荣王平阳 School of Mechanical Engineering Shanghai Jiaotong UniversityShanghai 200240People’s Republic of China Division of Electric propulsion Shanghai Institute of Space PropulsionShanghai 201112People’s Republic of China

Magnetic field design is essential for the operation of Hall *** study focuses on utilizing a genetic algorithm to optimize the magnetic field configuration of SPT70.A 2D hybrid PIC-DSMC and channel-wall erosion model are employed to analyze the plume divergence angle and wall erosion rate,while a Farady probe measurement and laser profilometry system are set up to verify the simulation *** results demonstrate that the genetic algorithm contributes to reducing the divergence angle of the thruster plumes and alleviating the impact of high-energy particles on the discharge channel wall,reducing the erosion by 5.5%and 2.7%,*** analysis indicates that the change from a divergent magnetic field to a convergent magnetic field,combined with the upstream shift of the ionization region,contributes to the improving the operation of the Hall thruster.

关键词： magnetic field design genetic algorithm divergence angle erosion of discharge channel convergent magnetic field