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	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 \| 收藏 \| 浏览/下载：52/0 \| 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.
	Recent development of passive dynamic walking (EI CONFERENCE) 会议论文 OAI收割 2011 International Conference on Energy, Environment and Sustainable Development, ICEESD 2011, October 21, 2011 - October 23, 2011, Shanghai, China 作者: Zhang P. 收藏 \| 浏览/下载：31/0 \| 提交时间：2013/03/25 The focus of this paper is a review on the recent development of passive dynamic walking. Passive dynamic walkers are introduced from the simple rimless wheel to the recently developed real two legged machines. Control strategies necessary to improve the stability and robustness of locomotion of passive dynamic walkers such as the hybrid geometric approach and the virtual constraints are discussed briefly. Finally the unresolved problems in the field of passive dynamic walking are summarized and directions of further developments are discussed. (2012) Trans Tech Publications Switzerland.
	Fixation of labeled ((NH4)-N-15)(2)SO4 and its subsequent release in black soil of Northeast China over consecutive crop cultivation 期刊论文 OAI收割 SOIL & TILLAGE RESEARCH, 2010, 卷号: 106, 期号: 2, 页码: 329-334 作者: Lu, Caiyan; Zhang, Xudong; Chen, Xin; Shi, Yi; Ma, Jian \| 收藏 \| 浏览/下载：20/0 \| 提交时间：2019/06/04 Soil Recently Fixed (Nh4++)-n-15 Soil n Fertility n Fertilization Practice Black Soil Of Northeast China
	The development and design of the gas-liquid two-phase flow-meter system based on DSP (EI CONFERENCE) 会议论文 OAI收割 2008 International Conference on Advanced Computer Theory and Engineering, ICACTE 2008, December 20, 2008 - December 22, 2008, Phuket, Thailand Zhu J.-W. 收藏 \| 浏览/下载：47/0 \| 提交时间：2013/03/25 Recently as the fast development of the modern engineer the measuring problem of the gas and liquid is becoming prominence and many countries spend so much in the research. The system with which the thesis developed has realized data acquisition data compression and decompression a friendly human-machine interface RS232 serial communication reading or writing USB disk. The architecture of system is flexible. The thesis presents a research on the measurement process and the whole structure of the flow metering system and analyzes the schematic circuit of the main hardware modules 2008 IEEE.
	Contour extracting with combination particle filtering and em algorithm (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photoelectronic Detection and Imaging, ISPDI 2007: Related Technologies and Applications, September 9, 2007 - September 12, 2007, Beijing, China Meng B.; Zhu M. 收藏 \| 浏览/下载：33/0 \| 提交时间：2013/03/25 The problem of extracting continuous structures from images is a difficult issue in early pattern recognition and image processings[1]. Tracking with contours in a filtering framework requires a dynamical model for prediction. Recently Particle filter is widely used because its multiple hypotheses and versatility within framework. However the good choice of the propagation function is still its main problem. In this paper an improved particle filter EM-PF algorithm is proposed which using the EM (Expectation-Maximization) algorithm to learn the dynamical models. The EM algorithm can explicitly learn the parameters of the dynamical models from training sequences. The advantage of using the EM algorithm in particle filter is that it is capable of improve tracking contour by having accurate model parameters. Though the experiment results we show how our EM-PF can be applied to produces more robust and accurate extracting.
	Packaging technology of polymer/Si arrayed waveguide grating and their environmental stability (EI CONFERENCE) 会议论文 OAI收割 2005 6th International Conference on Electronics Packaging Technology, August 30, 2005 - September 2, 2005, Dameisha, Shenzhen, China 作者: Zhang Y.; Zhang X.; Zhang X.; Zhang X.; Wang F. 收藏 \| 浏览/下载：33/0 \| 提交时间：2013/03/25 Future optical communication systems will use more of the exceptional high bandwidth of optical fiber. Wavelength division multiplexing (WDM) systems are well suited to transport terabits of information via the fiber[1]. Multiplexers/ demultiplexers (MUX/DEMUX) are essential components for dense WDM systems. Several different kinds of multiplexer types have been developed in the past: (a) interference filters (b) fiber gratings and (c) planar lightwave circuit (PLC) MUX/DEMUXers[2 3]. The planar fabrication process of the last mentioned PLCs allows the realization of high performance filters with a large number of wavelength channels. Further an integration with other optical elements seems to be possible. Arrayed waveguide gratings (AWG) are a special kind of PLC-MUX/DEMUXers which are very attractive components for WDM systems because of their great flexibility in filter design[4 5]. Basically an AWG is an optical spectrograph built in planar waveguide technique. Typically AWGs works in a high grating order (50-250). For AWG multiplexer applications in communications systems a precise wavelength controllability and wavelength stability with long term is demanded. Recently a polymeric (especially fluorinated polymer with low optical absorption loss in the infrared region) AWG has attracted much attention because of its easy fabrication low cost possibility and a potential of integration with other polymer devices[6]. Standard AWGs however show a change of center wavelength with temperature. A method to prevent this temperature drift is to package the AWG together with a temperature controller in order to tune and fix the desired filter-wavelength. In this paper a 32-channel AWG was fabricated using a cross-linkable fluorinated poly (ether ether ketone) (FPEEK) its package technology and environmental stability were also discussed. 2005 IEEE.
	Integrated optical amplifiers based on rare-earth doped (red) oxide glasses (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photonic Glass (ISPG 2002), October 14, 2002 - October 17, 2002, Shanghai, China 作者: Chen B.; Chen B. 收藏 \| 浏览/下载：41/0 \| 提交时间：2013/03/25 Oxide glasses have been used since long time to host a number of active compounds first of all rare-earth (RE) ions for lasing. Recently the advantages offered by guided-wave format namely the small size the high pump power density and the larger flexibility in design and fabrication led to the development of fiber lasers and amplifiers based on Er3+-doped glasses. Currently a growing activity is aimed at achieving large optical gain in Er3+-doped planar waveguides having in mind the single-chip realization of integrated optical amplifiers and lasers. The aim of the present paper is to provide a quick overview of this area and to briefly discuss possible future developments.