中国科学院机构知识库网格系统: 检索

Tracing Truth and Rumor Diffusions Over Mobile Social Networks: Who are the Initiators? 期刊论文 OAI收割
IEEE TRANSACTIONS ON MOBILE COMPUTING, 2023, 卷号: 22, 期号: 4, 页码: 2473-2490
作者: Qu, Shan; Xu, Hui; Fu, Luoyi; Long, Huan; Wang, Xinbing

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收藏 | 浏览/下载：12/0 | 提交时间：2024/01/04

Social networking (online) Optimization Indexes Blogs Diffusion processes Approximation algorithms Integrated circuit modeling Sources detection simultaneous diffusions of truth and rumor mobile social network algorithm design

Wavelet based tone mapping (TM) enhancement to a detection system for faint and compact sources in HDR and large FOV radio scenes 期刊论文 OAI收割
ASTRONOMY AND COMPUTING, 2023, 卷号: 42, 页码: 15
作者: Shan, H.; Cui, L.; Hong, X. Y.; Liu, X.; Chang, N.

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收藏 | 浏览/下载：53/0 | 提交时间：2023/03/01

Radio sources detection Detection criteria Tone mapping Wavelet Image enhancement Large field-of-view

No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文 OAI收割
Nature, 2020, 卷号: 587, 页码: 63-65
作者: HXMT

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收藏 | 浏览/下载：44/0 | 提交时间：2022/02/08

Astrophysics - High Energy Astrophysical Phenomena Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

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).

Design and detection for the photoelectric device used in the point source transmission testing 期刊论文 OAI收割
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument, 2018, 卷号: 39, 期号: 1, 页码: 92-99
作者: Zhang, Ning; Ye, Lu; Song, Ying

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收藏 | 浏览/下载：28/0 | 提交时间：2019/09/17

Signal detection Ability testing Light sources Light transmission Optical instruments Photoelectric devices Photoelectricity Stray light

Trajectory Community Discovery and Recommendation by Multi-Source Diffusion Modeling 期刊论文 OAI收割
IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING, 2017, 卷号: 29, 期号: 4, 页码: 898-911
作者: Liu, Siyuan; Wang, Shuhui

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收藏 | 浏览/下载：27/0 | 提交时间：2019/12/12

Community detection trajectory multiple information sources semantic information

Object Color Constancy for Outdoor Multiple Light Sources 会议论文 OAI收割
1st Chinese Conference on Computer Vision, CCCV 2015, Xi'an, China,, September 18-20, 2015,
作者: Qu LQ(屈靓琼); Duan ZG(段志刚); Tian JD(田建东); Han Z(韩志); Tang YD(唐延东)

收藏 | 浏览/下载：32/0 | 提交时间：2015/12/20

Object color constancy Illumination invariant Outdoor multiple light sources Object detection

Undersized humidity detecting system based on infrared spectrum absorption 期刊论文 OAI收割
qiangjiguang yu lizishu/high power laser and particle beams, 2011, 卷号: 23, 期号: 2, 页码: 363-366
Ju, Yu; Xie, Liang; Han, Wei; Sun, Ke

收藏 | 浏览/下载：43/0 | 提交时间：2012/06/13

Amplification Analog to digital conversion Lasers Light sources Sensors Signal detection Signal processing Standards Surface emitting lasers Water absorption Water vapor

The calibration of faint simulation star magnitude based on single photon count technique (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2009: Advances in Imaging Detectors and Applications, June 17, 2009 - June 19, 2009, Beijing, China
作者: Xu S.-Y.; Guo J.; Guo J.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

A calibration method of faint star magnitude of the star scene simulation device is proposed in this paper. In the research of simulation star magnitude luminometers and CCD devices are the general calibration devices which are used to measure the illumination intensity and calibrate its magnitude. But if the simulation magnitude is only sixth magnitude its illumination intensity is only 1.010-8 Lux. This illumination intensity level is the lowest illumination intensity that the commercial luminometer can detect. Hence the simulation star magnitude lower than six magnitude cannot be calibrated by luminoters. Likewise CCD devices also need an additive cooler in this case. When the single photon characteristic is presented due to the low luminosity of simulating light sources the simulation star magnitude can be calibrated by detecting its photon flux of radiation with the method of single photon count. In this paper the detection principle of single photon based on a compact designed PMT detecting of the radiation level of simulation star magnitude is advanced. Especially a spectrum match method is proved theoretically to be an effective means for selecting PMT photosensitive type. In the case of the detection object of the simulation star in visible wavelength a analysis indicates that the material of tri-alkali cathode materials its best choice after being compared the Signal-to-Noise of photon detector of several PMT photosensitive materials based on the different spectrum match ratio of different object light sources and different cathode materials. An experiment is employed to show the relationship of control voltage of PMT and its dark counter the relationship of the environment temperature of PMT and its dark counter which proves its only decades of CPS at room temperature. The so low dark counter avoids a bulky cooler and is convenient for installing it on the star scene simulation equipment. Finally in the experiment of calibrating the simulation star magnitudes the ability of its calibration is confirmed to reaches up to 12m meanwhile its calibration error is within 0.2m. 2009 SPIE.

Measurement of the frequency spectrum of a submillimeter CW source by heterodyne mixing and direct detection 期刊论文 OAI收割
JOURNAL OF INFRARED AND MILLIMETER WAVES, 2005, 卷号: 24, 期号: 5, 页码: 321-+
作者: Shen, XF; Yao, QJ; Lin, ZH; Shi, SC

收藏 | 浏览/下载：27/0 | 提交时间：2012/03/07

frequency spectrum submillimeter sources heterodyne mixing direct detection FTS