中国科学院机构知识库网格系统: 检索

Noise removal for semi-airborne data using wavelet threshold and singular value decomposition 期刊论文 OAI收割
JOURNAL OF APPLIED GEOPHYSICS, 2022, 卷号: 201, 页码: 11
作者: Lv, Pengfei; Wu, Xin; Zhao, Yang; Chang, Jianghao

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Semi-airborne transient electromagnetic method Short-time sliding window Singular spectrum decomposition Wavelet threshold method Noise processing

Clocking the buildup dynamics of light-induced states through attosecond transient absorption spectrum 期刊论文 OAI收割
Journal of Physics B: Atomic, Molecular and Optical Physics, 2021, 卷号: 54, 期号: 20, 页码: 7
作者: Wu,Xiaoxia; Zhang,Shaofeng; Ye,Difa

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收藏 | 浏览/下载：46/0 | 提交时间：2022/01/07

attosecond transient absorption spectrum light-induced states AC-Stark shift Floquet theory three-level system

A Revised Hilbert-Huang Transformation to Track Non-Stationary Association of Electroencephalography Signals 期刊论文 OAI收割
IEEE TRANSACTIONS ON NEURAL SYSTEMS AND REHABILITATION ENGINEERING, 2021, 卷号: 29, 页码: 841-851
作者: Shan, Xiaocai; Huo, Shoudong; Yang, Lichao; Cao, Jun; Zou, Jiaru

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收藏 | 浏览/下载：42/0 | 提交时间：2021/10/19

Electroencephalography Time-frequency analysis Transforms Wavelet transforms Oscillators Signal resolution Physiology EEG transient connectivity cross-spectrum Hilbert Huang transform

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：28/0 | 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).

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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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.

Research on the Method of Transient Spectrum Detection Based on Array CCD 期刊论文 OAI收割
spectroscopy and spectral analysis, 2012, 卷号: 32, 期号: 4, 页码: 1028-1031
作者: Zhu Bing-li; Bai Yong-lin; Wang Bo; Liu Bai-yu; Ouyang Xian

收藏 | 浏览/下载：27/0 | 提交时间：2015/07/02

Linear CCD Array CCD CCD high speed imaging Transient spectrum detection

The angular velocity estimation principal of -- filter based on high sampling rate (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Zhang Y.

收藏 | 浏览/下载：34/0 | 提交时间：2013/03/25

In order to get angular velocity of stabilization servo mechanism from angular position sensors -- filter and its angular velocity transfer function were predigested. Combing with optimum parameters -- filter based on high sampling rate was established the effect of and sample rate on filter nature frequency were evaluated. According to the requirements of stabilization platform the principle of steady and transient tracking filter differential were proved. With the hypothesis of constant acceleration the frequency characteristics of angular velocity transfer function were analyzed three-dimensional Kalman filter was simplified and the filter parameters were designed. The results show that when the spectrum of input signal was lower than 6rad/s parameters was 0.02 and sampling period were 0.08ms and 0.1ms respectively the filter can realize differential exactly when the spectrum was 9rad/s the precision was no less than 1.1% the phase leading of angular position was no less than 70 the natural frequency should be higher than the cut-off frequency of stabilization platform was two or three times. In the engineering of electro-optical stabilization servo mechanism -- filter has properties of tracking differential and reached the requirement of platform angular velocity estimation. Also it is one of the effective methods to get angular velocity from angular position sensors. 2011 IEEE.

Energy transfer among chlorophylls in trimeric light-harvesting complex II of Bryopsis corticulans 期刊论文 OAI收割
acta biochimica et biophysica sinica, 2006, 卷号: 38, 期号: 5, 页码: 310-317
作者: Zhang, SJ; Wang, SC; He, JF; Chen, H

收藏 | 浏览/下载：21/0 | 提交时间：2015/08/19

energy transfer LHC II transient spectrum fluorescence kinetics

Investigation on the properties of the transient absorption of cyclometallated Pt(II) complexes using picosecond and nanosecond laser-flash photolysis 期刊论文 OAI收割
RESEARCH ON CHEMICAL INTERMEDIATES, 2004, 卷号: 30, 期号: 4-5, 页码: 489-494
作者: Xiong, F; Li, SY; Gan, Q; Gan, SK; Li, Y

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收藏 | 浏览/下载：10/0 | 提交时间：2019/04/09

Metal Complex Transient Absorption Spectrum

Investigation on the properties of the transient absorption of cyclometallated pt(ii) complexes using picosecond and nanosecond laser-flash photolysis 期刊论文 iSwitch采集
Research on chemical intermediates, 2004, 卷号: 30, 期号: 4-5, 页码: 489-494
作者: Xiong, F; Li, SY; Gan, Q; Gan, SK; Li, Y

收藏 | 浏览/下载：31/0 | 提交时间：2019/05/10

Metal complex Transient absorption spectrum