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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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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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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.

Molecular Weight Dependency of Crystallization and Melting Behavior of beta-Nucleated Isotactic Polypropylene 期刊论文 OAI收割
journal of polymer science part b-polymer physics, 2014, 卷号: 52, 期号: 19, 页码: 1301-1308
Lu, Ying; Wang, Qiao; Men, Yongfeng

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Compounds of isotactic polypropylene (iPP) and beta-nucleating agent were used to investigate the relationship between the development of beta phase and molecular weight in iPP under quiescent crystallization conditions by using wide angle X-ray diffraction and differential scanning calorimetry techniques. In all cases the dependency of the formation of beta phase in iPP on molecular weight of iPP at a defined crystallization temperature range was found. The iPP with high molecular weight possessed a wide range of crystallization temperature in inducing rich beta phase. However poor or even no beta phase was obtained for the samples with low molecular weight in the same range. In addition an upper critical crystallization temperature of producing dominant beta phase was found at 125 degrees C. Beyond this temperature a phenomenon of prevailing alpha phase became obvious. (C) 2014 Wiley Periodicals Inc.

Tribological properties of Mos2 thin coatings under liquid lubricating (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Innovation Manufacturing and Engineering Management, IMEM 2012, December 14, 2012 - December 16, 2012, Chongqing, China
Bai Y.; Cao P.

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The objective of this study is to investigate the effect of solid and liquid lubrication on friction and wear performance of selected solid lubricating coatings comparative experiments have been carried out on magnetron sputtered MoS2 coatings against Si3N4 ball using a ball-on-disk tribo-tester under the conditions of room temperature and different lubrication. Surface morphology of coatings were investigated by atom force microscope (AFM) and friction coefficient (COF) and wear rate of solid films were also be analyzed. It was shown that the friction is greatly reduced when the solid film is lubricated with oil and grease simultaneously in comparison with single-lubricant lubrication at the start-up or under boundary lubrication conditions. Liquid lubrication causes a dramatic decrease of the wear-ability of the MoS2 coatings. The effect of oil lubrication to the deterioration of wear resistance of MoS2 film was even worse than lubrication grease. (2013) Trans Tech Publications Switzerland.

Assessment of soil redistribution and spatial pattern for a small catchment in the black soil region, Northeastern China: Using fallout Pb-210(ex) SCI/SSCI论文 OAI收割
2013
Fang H. Y.; Sheng M. L.; Tang Z. H.; Cai Q. G.

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Pb-210(ex) Soil redistribution Agricultural catchment Black soil region of Northeastern China cs-137 technique erosion rates cultivated land northern spain models calibration investigate deposition gullies morocco

Modeling and variable structure control of a vehicle flexible manipulator (EI CONFERENCE) 会议论文 OAI收割
10th World Congress on Intelligent Control and Automation, WCICA 2012, July 6, 2012 - July 8, 2012, Beijing, China
作者: Wang Z.; Li Y.; Li Y.; Li Y.; Li Y.

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In this paper the mathematical modeling and the application of a new trajectory tracking control technique for hydraulic-driven rigid-flexible manipulator are concerned. To get a closer dynamic behavior of the real system both the flexible manipulator linkage and the actuator dynamics are considered. The exact dynamic model of flexible manipulator is derived using Lagrange principle and assumed modes method. The partial decoupled dynamic equation is derived using nonlinear decoupling feedback control method. The whole dynamic model is established by a driven Jacobin matrix which represents the coupling between hydraulic servo system and mechanical system. A variable structure controller with inverse dynamics is designed for trajectory tracking. To weaken the chattering of control signal saturation function is used to instead of sign function. The experimental results investigate the effectiveness of the proposed approaches. 2012 IEEE.

Experiments and finite element simulations on micro-milling of aluminium alloy7050-T7451 (EI CONFERENCE) 会议论文 OAI收割
10th Asia-Pacific Conference on Materials Processing, APCMP 2012, June 14, 2012 - June 17, 2012, Jinan, China
作者: Li J.; Li J.; Li J.; Zhou J.; Wang F.

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The mechanism of micro-milling modeling for aluminum alloy 7050-T745 is to be investigated and a finite element model for micro-milling that reflects the actual state of the three-dimensional micro-milling is built by adopting the software of ABAQUS/Explicit. Experiment is conducted to verify the validation of the model. Simulated chip morphology in different cutting parameters agrees to the experimental results very well. Based on the FE model cutting stresses equivalent plastic strains temperatures distribution and cutting forces are obtained and analyzed. This provides a good method to investigate the micro milling principles. (2012) Trans Tech Publications.

Statistical Characteristics of Evaporating-Freezing Process of Water Droplet during Quick Depressurization 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: Du WF(杜王芳); Zhao JF(赵建福); Kang Q(康琦)

收藏 | 浏览/下载：47/0 | 提交时间：2014/04/02

Process during Water freezing latent saturation system flashing liquid observed flowed suddenly investigate value first water frozen again until inside 0

Information extraction from laser speckle patterns using wavelet entropy techniques (EI CONFERENCE) 会议论文 OAI收割
MIPPR 2011: Multispectral Image Acquisition, Processing, and Analysis, November 4, 2011 - November 6, 2011, Guilin, China
作者: Li X.-Z.; Wang X.-J.

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A novel speckle patterns processing method is presented using multi-scale wavelet techniques. Laser speckle patterns generated from the sample contained abundant information. In this paper we propose a method using wavelet entropy techniques to analyze the speckle patterns and exact the information on the sample surface. In our case we used this approach to test the solar silicon cell surface profiles based on the sym8 orthogonal wavelet family. According different wavelet entropy values the micro-structure of different solar silicon cell surfaces were comparative analyzed. Furthermore we studied the AFM and reflective spectra of the wafer. Results show that the wavelet entropy speckle processing method is effective and accurate. And the experiment proved that this method is a useful tool to investigate the surface profile quality. 2011 SPIE.

A study on atmospheric turbulence effects in full-optical free-space communication systems (EI CONFERENCE) 会议论文 OAI收割
2010 6th International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2010, September 23, 2010 - September 25, 2010, Chengdu, China
作者:

收藏 | 浏览/下载：23/0 | 提交时间：2013/03/25