中国科学院机构知识库网格系统: 检索

Multidisciplinary and multiscale nanoscience research roadmap based on large scientific facilities 期刊论文 OAI收割
SCIENCE CHINA-CHEMISTRY, 2024
作者: Zeng, Yuan; Zhang, Shuhan; Guo, Yuecong; Cong, Yalin; Ding, Xu

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收藏 | 浏览/下载：7/0 | 提交时间：2024/11/20

large scientific facilities synchrotron radiation FEL light sources neutron sources spectroscopic analysis methods X-ray imaging techniques structural information chemical dynamics

Experimental study of hydraulic fracture initiation and propagation in deep shale with different injection methods 期刊论文 OAI收割
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING, 2022, 卷号: 216, 期号: -, 页码: -
作者: Chang, Xin; Xu, Ersi; Guo, Yintong; Yang, Chunhe; Hu, Zhiwen

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收藏 | 浏览/下载：17/0 | 提交时间：2023/08/02

Deep shale gas Hydraulic fracturing Injection methods Cyclic fluid injection Acoustic emission (AE) X-ray CT scanning

Higher valency ion substitution causing different fluorite-derived structures in CaZr1-xNdxTi2-xNbxO7 (0.05 <= x <= 1) solid solution 期刊论文 OAI收割
CERAMICS INTERNATIONAL, 2021, 卷号: 47, 期号: 2, 页码: 2694-2704
作者: Ji, Shiyin; Liao, Chang-Zhong; Chen, Shuangqiang; Zhang, Kuibao; Shih, Kaimin

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收藏 | 浏览/下载：33/0 | 提交时间：2021/12/13

Fluorite-derived structures Substitution mechanism Evolutions of crystal structure X-ray methods

Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文 OAI收割
The Astrophysical Journal, 2020, 卷号: 901, 页码: L7
作者: HXMT

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收藏 | 浏览/下载：23/0 | 提交时间：2022/02/08

Radio transient sources Magnetars Soft gamma-ray repeaters 2008 992 1471 Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Instrumentation and Methods for Astrophysics Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of A_J = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 10¹⁴ Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to R_NIR ? 0.025 (fluence index ?0.35).

Comparison of simulated backgrounds with in-orbit observations for HE, ME, and LE onboard Insight-HXMT 期刊论文 OAI收割
Astrophysics and Space Science, 2020, 卷号: 365, 页码: 158
作者: HXMT

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收藏 | 浏览/下载：48/0 | 提交时间：2022/02/08

Insight-HXMT Geant4 simulation Background observation Astrophysics - Instrumentation and Methods for Astrophysics Abstract: Insight-HXMT, the first X-ray astronomical satellite in China, aims to reveal new sources in the Galaxy and to study fundamental physics of X-ray binaries from 1 to 250 keV. It has three collimated telescopes, the High Energy X-ray telescope (HE), the Medium Energy X-ray telescope (ME), and the Low Energy X-ray telescope (LE). Before the launch, in-orbit backgrounds of these three telescopes had been estimated through Geant4 simulation, in order to investigate the instrument performance and the achievement of scientific goals. In this work, these simulated backgrounds are compared with in-orbit observations. Good agreements are shown for all three telescopes. For HE, (1) the deviation of the simulated background rate after two years of operation in space is 5 % from the observation (2) the total background spectrum and the relative abundance of the 67 keV line show long-term increases both in simulations and observations. For ME, (1) the deviation of simulated background rate is within 15 % from the observation, and (2) there are no obvious long-term increase features in the background spectra of simulations and observations. For LE, the background level given by simulations is also consistent with observations. The consistencies of these comparisons validate that the Insight-HXMT mass model, i.e., space environment components and models adopted, physics processes selected, and detector constructions built, is reasonable. However, the line features at 7.5 and 8.0 keV, which are obvious in the observed spectra of LE, are not evident in simulations. This might result from uncertainties in the LE constructions.

An underlying clock in the extreme flip-flop state transitions of the black hole transient Swift J1658.2-4242 期刊论文 OAI收割
Astronomy and Astrophysics, 2020, 卷号: 641, 页码: A101
作者: HXMT

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收藏 | 浏览/下载：58/0 | 提交时间：2022/02/08

accretion accretion disks black hole physics X-rays: binaries time Astrophysics - High Energy Astrophysical Phenomena Abstract:
Aims: Flip-flops are top-hat-like X-ray flux variations, which have been observed in some transient accreting black hole binary systems, and feature simultaneous changes in the spectral hardness and the power density spectrum (PDS). They occur at a crucial time in the evolution of these systems, when the accretion disc emission starts to dominate over coronal emission. Flip-flops remain a poorly understood phenomenon, so we aim to thoroughly investigate them in a system featuring several such transitions.
Methods: Within the multitude of observations of Swift J1658.2-4242 during its outburst in early 2018, we detected 15 flip-flops, enabling a detailed analysis of their individual properties and the differences between them. We present observations by XMM-Newton, NuSTAR, Astrosat, Swift, Insight-HXMT, INTEGRAL, and ATCA. We analysed their light curves, searched for periodicities, computed their PDSs, and fitted their X-ray spectra, to investigate the source behaviour during flip-flop transitions and how the interval featuring flip-flops differs from the rest of the outburst.
Results: The flip-flops of Swift J1658.2-4242 are of an extreme variety, exhibiting flux differences of up to 77% within 100 s, which is much larger than what has been seen previously. We observed radical changes in the PDS simultaneous with the sharp flux variations, featuring transitions between the quasi-periodic oscillation types C and A, which have never been observed before. Changes in the PDS are delayed, but more rapid than changes in the light curve. Flip-flops occur in two intervals within the outburst, separated by about two weeks in which these phenomena were not seen. Transitions between the two flip-flop states occurred at random integer multiples of a fundamental period of 2.761 ks in the first interval and 2.61 ks in the second. Spectral analysis reveals the high and low flux flip-flop states to be very similar, but distinct from intervals lacking flip-flops. A change of the inner temperature of the accretion disc is responsible for most of the flux difference in the flip-flops. We also highlight the importance of correcting for the influence of the dust scattering halo on the X-ray spectra.

Applying maximally stable extremal regions and local binary patterns for guide-wire detecting in percutaneous coronary intervention 期刊论文 OAI收割
IET IMAGE PROCESSING, 2019, 卷号: 13, 期号: 13, 页码: 2579-2586
作者: Pusit, Prasong; Xie, Xiao-Liang; Hou, Zeng-Guang

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收藏 | 浏览/下载：49/0 | 提交时间：2020/03/30

blood vessels medical image processing surgery image sequences video signal processing image filtering object detection X-ray imaging object tracking stroke width variation filter region detection local binary patterns guide-wire recognition conventional MSER methods maximally stable extremal regions guide-wire position anatomical skeleton contours training data X-ray video sequence percutaneous coronary intervention surgery region area range filter X-ray video monitoring guide-wire tip detection modified multifilters training templates

Synchrotron x-ray spectroscopy investigation of the Ca(1-x)Ln(x)ZrTi(2-x)(Al, Fe)(x)O-7 zirconolite ceramics (Ln = La, Nd, Gd, Ho, Yb) 期刊论文 OAI收割
JOURNAL OF THE AMERICAN CERAMIC SOCIETY, 2019, 页码: 13
作者: Ji, Shiyin; Su, Minhua; Liao, Changzhong; Ma, Shengshou; Wang, Zhiguang

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收藏 | 浏览/下载：15/0 | 提交时间：2022/01/19

nuclear waste phase transformations x-ray methods zirconolite-2M

Formation peculiarities and optical properties of highly-doped (Y(0.86)La(0.09)Vb(0.05))(2)O-3 transparent ceramics 期刊论文 OAI收割
CERAMICS INTERNATIONAL, 2019, 卷号: 45, 期号: 13, 页码: 16002
作者: Kryzhanovska, O. S.; Baumer, V. N.; Parkhomenko, S., V; Doroshenko, A. G.; Yavetskiy, R. P.

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收藏 | 浏览/下载：56/0 | 提交时间：2019/12/26

Sintering X-ray methods Optical properties Y2O3 Functional application

In-orbit Demonstration of X-Ray Pulsar Navigation with the Insight-HXMT Satellite 期刊论文 OAI收割
The Astrophysical Journal Supplement Series, 2019, 卷号: 244, 页码: 1
作者: HXMT

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收藏 | 浏览/下载：13/0 | 提交时间：2022/02/08

pulsars: general techniques: miscellaneous Astrophysics - Instrumentation and Methods for Astrophysics Abstract: In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT) Satellite, which was launched on 2017 June 15. The new pulsar navigation method Significance Enhancement of Pulse-profile with Orbit-dynamics is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from 2017 August 31 to September 5. Using the five-day long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard: High Energy X-ray Telescope, Medium Energy X-ray Telescope, and Low Energy X-ray Telescope, respectively. By combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3ҩ and 10 m s^-1 (3ҩ, respectively.