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On the Terrestrial Gamma Ray Flashes Preceding Narrow Bipolar Events 期刊论文 OAI收割
Geophysical Research Letters, 2021, 卷号: 48, 页码: e92160
作者: HXMT

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low frequency magnetic sferics narrow bipolar events (NBEs) relativistic feedback mechanism Terrestrial Gamma ray Flashes (TGFs) Abstract: Narrow bipolar events (NBEs) are occasionally reported to occur within a few ms after Terrestrial Gamma ray Flashes (TGFs), while the formation mechanism remains mysterious partially due to the lack of sufficient observations. Here, nine more TGFs of this scenario are reported with concurrent LF sferics and lightning location data. The gamma ray production in these TGFs preceded the occurrence of NBEs by a minimum of 60 µs up to 13.5 ms, and no other fast leader discharge was found within 20 ms before the TGF. The TGF preceded positive NBEs occurred at altitudes of 8.6-11 km in thunderstorms, likely in the high electric field (E field) region of lightning initiation. The analyses show that the NBE preceding TGFs bear harder energy spectrum with larger proportion of high energy photons than EIP related TGFs produced in association with lightning leader. Our findings support the relativistic feedback mechanism of gamma ray generation in the large scale thunderstorm E field.

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.

Luminescence and energy transfer in Ca3Sc2Si 3O12:Ce3+,Mn2+ white LED phosphors (EI CONFERENCE) 会议论文 OAI收割
作者: Luo Y.; Zhang J.; Zhang J.; Zhang J.; Wang X.

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Expanded emission spectra ranging from green to red are reported in Ca 3Sc2Si3O12 (CSS):Ce 3+ Mn2+ silicate garnets. Mn2+ may occupy Ca2 site (Mn2+(I)) to generate a yellow emission band at 574 nm or Sc3 site (Mn2+(II)) with red emission band at 680 nm. Efficient energy transfers from the green emitting Ce3+ to both Mn2+(I) and Mn2+(II) occur upon blue excitation into Ce3+. Concentration dependence of Mn2+ emission is analyzed based on Ce3+-Mn2+ energy transfer steady state rate equations and fluorescence lifetimes. Energy transfer efficiency (nT) and rate (W) are calculated with values as high as 45% and 14.01106 s-1 respectively. 2011 Elsevier B.V.

Research on load-bearing characteristics of precision air-bearing rotary stage (EI CONFERENCE) 会议论文 OAI收割
3rd international Conference on Manufacturing Science and Engineering, ICMSE 2012, March 27, 2012 - March 29, 2012, Xiamen, China
作者: Wang L.; Wang L.; Wang L.; Lin J.

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Air-bearing is a core component of air-bearing rotary stage. The weakness that the air-bearing has the low load capacity and stiffness has been concerned about by domestic and foreign scholars. So how to improve the load capacity and stiffness has become a serious problem. In order to improve the load capacity and stiffness of the air-bearing rotary stage in this paper we improved structure of Zhang Wenjie and others' high-precision direct-drive air-bearing rotary stage. The gas film of air-bearing has been meshed by GAMBIT software and we use FLUENT software to obtain the carrying capacity features of the gas film. Finally the structural static force of the precision air-bearing rotary stage will be analyzed by ANSYS software. The analysis results show that: the structural design of the precision air-bearing rotary stage is reasonable and this structure can provide a larger range of loads. Even in heavy load conditions a larger deformation will not occur any more. It has a good practical value and also can be widely used in high precision equipments. (2012) Trans Tech Publications.

Study of horizontal shafting with spherical four-way structure (EI CONFERENCE) 会议论文 OAI收割
2012 International Conference on Optoelectronics and Microelectronics, ICOM 2012, August 23, 2012 - August 25, 2012, Changchun, China
作者: Yang L.; Yang L.

收藏 | 浏览/下载：35/0 | 提交时间：2013/03/25

Altazimuth photoelectric theodolite level shaft U-type and T-type structure but with the expanding field of applications of photoelectric theodolite the horizontal shaft structure occur great changes. For example in the marine environment shipboard conditions the instrument has a waterproof corrosion-resistant easy maintenance and other functions while carrier-based optoelectronic devices from a single visible television configure the development of integrated infrared system and ranging system as one of the single-station measurement system due to the spherical structure has sufficient internal space exactly adapted to this need. In this paper the horizontal axis of a spherical four-way structure. From aspects of the spherical four-way split in the form and shafting design and finite element analysis of the detailed design. A spherical four-way horizontal axis system diameter 550mm weight 19kg sphere in the 40kg load the maximum deformation of 3.3m fully meet the requirements. The shaft of the structure of the shaking is less than 2 arc seconds the vibration test the re-examination instrument accuracy change is less than 1 arc seconds. Verify that the structure is stable and reliable. 2012 IEEE.

Instabilities in a horizontal liquid layer in co-current gas flow with an evaporating interface 会议论文 OAI收割
Asian Microgravity Pre-Symposium 9th China-Japan-Korea Workshop on Microgravity Sciences, 中国广西桂林/Guilin, China, 2012-10-29
作者: Liu R(刘荣); Liu QS(刘秋生); Kabov OA

收藏 | 浏览/下载：22/0 | 提交时间：2014/04/02

evaporating liquid interface horizontal layer current streamwise rigid stability studied buoyancy gradient driven Chebyshev occur bounded walls system Phase shear

Establishment of airplane flight model and simulation analysis of landing behavior (EI CONFERENCE) 会议论文 OAI收割
2nd Annual Conference on Electrical and Control Engineering, ICECE 2011, September 16, 2011 - September 18, 2011, Yichang, China
作者: Li L.; Li M.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

This paper create a high fidelity plant model of an aircraft landing gear to inclusion into a full aircraft flight simulation for accurately analyzing the performance and influence of landing gear system. The use of domain specific modeling software enables detailed modeling of the physics and facilitates accurate computational simulation of the flight dynamic aerodynamic landing gear dynamic and mechanical loads that occur when the landing gear are deployed and retracted during landing and take-off operations. The parameter design space is easily searched by considering a number of different landing scenarios including touching down on one wheel first to optimize the design. The simulation results show that the aircraft landing gear system mathematical model established appropriately reflects the change of force and moment in the process of taking off and landing and it is actual in the physical process. 2011 IEEE.

Aircraft landing gear simulation using multidomain modeling technology (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Information Technology, Computer Engineering and Management Sciences, ICM 2011, September 24, 2011 - September 25, 2011, Nanjing, Jiangsu, China
作者: Li M.

收藏 | 浏览/下载：44/0 | 提交时间：2013/03/25

In order to accurately analyze the performance and influence of landing gear system this paper presents a high fidelity plant model of an aircraft landing gear to inclusion into a full aircraft flight simulation. The use of domain specific modeling software enables detailed modeling of the physics and facilitates accurate computational simulation of the flight dynamic aerodynamic landing gear dynamic and mechanical loads that occur when the landing gear are deployed and retracted during landing and take-off operations. The parameter design space is easily searched by considering a number of different landing scenarios including touching down on one wheel first to optimize the design. The simulation results show that the aircraft landing gear system mathematical model established appropriately reflects the change of force and moment in the process of taking off and landing and it is improve the precision of flight simulation. 2011 IEEE.

Study of three-mode parametric instability (EI CONFERENCE) 会议论文 OAI收割
8th Edoardo Amaldi Conference on Gravitational Waves, June 21, 2009 - June 26, 2009, New York, NY, United states
Liang F.; Zhao C.; Gras S.; Ju L.; Blair G.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

The effect of parametric instability in advanced interferometric gravitational wave detectors is a potential problem for their proper operation. Great efforts have been made to study the onset of parametric instabilities and to find ways to control them. Here we present an experimental design for studying parametric instability in a 72 m cavity with suspended high quality fused silica mirrors. With 5 W input power and 20 kW circulation power inside the cavity it is predicted that parametric instability will occur. The resonant condition of parametric instability can be met by thermally tuning the radius of curvature of a test mass. We will present simulation results of parametric gains for different radii of curvature of a test mass. The simulation results will provide the basis for designing the thermal tuning and observation parametric instability experiments. This will provide a test bed for studying parametric instability and its control for next generation detectors. 2010 IOP Publishing Ltd.

1.2 A General Survey of Debris Flow Hazards in China 专著章节/文集论文 OAI收割
出自: JAPAN-CHINA JOINT RESEARCH ON THE PREVENTION FROM DERIS FLOW HAZARDS, Kyoto Univesrity, Kyoto Univesrity:Tanaotsu Takahashi (Disaster Prevention Reserch Instiue, Kyoto Univesrity), Tanaotsu Takahashi (Disaster Prevention Reserch Instiue, Kyoto Univesrity), 1994, 页码: 5-10
作者: Wu Jishan

收藏 | 浏览/下载：23/0 | 提交时间：2015/08/28

frequently occur debris flows mountain areas China frequently occur debris flows mountain areas China