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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.

Timing analysis of Swift J1658.2-4242's outburst in 2018 with Insight-HXMT, NICER and AstroSat 期刊论文 OAI收割
Journal of High Energy Astrophysics, 2019, 卷号: 24, 页码: 30-40
作者: HXMT

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收藏 | 浏览/下载：56/0 | 提交时间：2022/02/08

Accretion accretion disks Black hole physics X-rays: binaries: Swift J1658.2-4242 Astrophysics - High Energy Astrophysical Phenomena Abstract: We present the observational results from a detailed timing analysis of the black hole candidate Swift J1658.2-4242 during its 2018 outburst with the observations of Hard X-ray Modulation Telescope (Insight-HXMT), Neutron Star Interior Composition Explorer (NICER) and AstroSat in 0.1-250 keV. The evolution of intensity, hardness and integrated fractional root mean square (rms) observed by Insight-HXMT and NICER are presented in this paper. Type-C quasi-periodic oscillations (QPOs) observed by NICER (0.8-3.5 Hz) and Insight-HXMT (1-1.6 Hz) are also reported in this work. The features of the QPOs are analyzed with an energy range of 0.5-50 keV. The relations between QPO frequency and other characteristics such as intensity, hardness and QPO rms are carefully studied. The timing and spectral properties indicate that Swift J1658.2-4242 is a black hole binary system. Besides, the rms spectra of the source calculated from the simultaneous observation of Insight-HXMT, NICER and AstroSat support the Lense-Thirring origin of the QPOs. The relation between QPO phase lag and the centroid frequency of Swift J1658.2-4242 reveals a near zero constant when < 4Hz and a soft phase lag at 6.68 Hz. This independence follows the same trend as the high inclination galactic black hole binaries such as MAXI J1659-152.

In-orbit Demonstration of X-Ray Pulsar Navigation with the Insight-HXMT Satellite 期刊论文 OAI收割
The Astrophysical Journal Supplement Series, 2019, 卷号: 244, 页码: 1
作者: HXMT

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pulsars: general techniques: miscellaneous Astrophysics - Instrumentation and Methods for Astrophysics Abstract: In this work, we report the in-orbit demonstration of X-ray pulsar navigation with Insight-Hard X-ray Modulation Telescope (Insight-HXMT) Satellite, which was launched on 2017 June 15. The new pulsar navigation method Significance Enhancement of Pulse-profile with Orbit-dynamics is adopted to determine the orbit with observations of only one pulsar. In this test, the Crab pulsar is chosen and observed by Insight-HXMT from 2017 August 31 to September 5. Using the five-day long observation data, the orbit of Insight-HXMT is determined successfully with the three telescopes onboard: High Energy X-ray Telescope, Medium Energy X-ray Telescope, and Low Energy X-ray Telescope, respectively. By combining all the data, the position and velocity of the Insight-HXMT are pinpointed to within 10 km (3ҩ and 10 m s^-1 (3ҩ, respectively.

Effect of Zn doping on the hydrogenolysis of glycerol over ZnNiAl catalyst 期刊论文 OAI收割
journal of molecular catalysis a-chemical, 2014, 卷号: 395, 页码: 1-6
Li, Xiaoru; Zhang, Chao; Cheng, Haiyang; He,Limin; Lin,Weiwei; Yu,Yancun; Zhao,Fengyu

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Nickel based catalyst is of interest in the industrial catalytic processes and it is always modified by doping a second element to improve its catalytic properties. Understanding the role of dopant is extremely helpful in tailoring the active centers. In this work Zn could induce a significant improvement of the catalytic performance of NiAl for the hydrogenolysis of glycerol. The Zn doped ZnNiAl catalysts exhibited high activity and the improved selectivity to 1 2-propanediol it was about 2 times higher than the original ones. The ZnNi alloy formed in ZnNiAl was responsible for the noticeable catalytic performance. They preferred to coordinate with the end hydroxyl group of glycerol promoted the cleavage of C-O bond in glycerol and resulted in the dominant formation of 1 2-propanediol. The findings described here will provide a useful knowledge for rational design of nickel-based catalysts as well as reveal a new reaction model for the hydrogenolysis of glycerol. (C) 2014 Elsevier B.V. All rights reserved.

Gradient Structure-Induced Temperature Responsiveness in Styrene/Methyl Methacrylate Gradient Copolymers Micelles 期刊论文 OAI收割
macromolecular rapid communications, 2014, 卷号: 35, 期号: 3, 页码: 309-316
Zheng,Chao; Huang,Haiying; He,Tianbai

收藏 | 浏览/下载：24/0 | 提交时间：2015/10/15

In this work micelles are formed by gradient copolymer of styrene and methyl methacrylate in acetone-water mixture and their temperature responsiveness is investigated in a narrow range near room temperature. Three different kinds of structural transitions could be induced by temperature: unimers to micelle transition shrinkage/stretching of micelles and morphological transition from spherical micelles to vesicles. In addition a model analysis on the interface of gradient copolymer micelle is made to better understand these phenomena. It is found that both position and composition of the interface could alter in response to the change in temperature. According to the experiments and model analysis it is proposed that temperature responsiveness might be an intrinsic and universal property of gradient copolymer micelles which only originates from the gradient structure.

A novel algorithm for action landmarks extraction (EI CONFERENCE) 会议论文 OAI收割
2012 2nd International Conference on Advanced Materials and Computer Science, ICAMCS 2012, December 27, 2012 - December 28, 2012, Xiamen, China
作者: Zhao J.

收藏 | 浏览/下载：15/0 | 提交时间：2013/03/25

In this work we present a new algorithm for extracting action landmarks from proposition landmarks graph. Compared to published approaches the action landmarks extraction algorithm we proposed can find more disjunctive action landmarks and single action landmarks. We illustrate our ideas with experiments among benchmark domains. The experiments show that the new algorithm is competitive with traditional algorithm for finding action landmarks from relaxed plan graph. (2013) Trans Tech Publications Switzerland.

Laser cleaning of neutral attenuator plate based on low power laser diode (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Energy, Environment and Sustainable Development, EESD 2012, October 12, 2012 - October 14, 2012, Jilin, China
作者: Chen Y.; Li L.

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Laser cleaning is a non-contact green and environmental cleaning method which can effectively remove particulate contaminations of sizes as small as 0.1 m without damage to the optics. But most laser cleaning devices are large and heavy also expensive due to using large lasers such as CO2 laser YAG Laser etc. In this work a low power LD was tried to clean fingerprint and dust contaminated on the surface of the attenuator glasses plates. In the laser cleaning experiment with low power diode the fingerprint grease can be efficient to be cleaned but there is no evident effect for cleaning inorganic dust. The cleaning different degree of fingerprint contaminations was investigated at the variable laser parameters including laser power and irradiation time. An optical microscope was used to analyze the cleaning effect. The results show that low power LD can effectively remove the fingerprint on the surface of absorptive-type attenuator glass plates. On the premise that the attenuator optics glasses are not damaged the cleaning area increases with the increase of radiation time and laser power. The cleaning area doesn't change much with the variation of laser frequency when the other parameters are the same. (2013) Trans Tech Publications Switzerland.

The application of digital signal processing (DSP) for the real time solving of artillery fire control exterior trajectory (EI CONFERENCE) 会议论文 OAI收割
2012 IEEE 3rd International Conference on Software Engineering and Service Science, ICSESS 2012, June 22, 2012 - June 24, 2012, Beijing, China
作者: Li D.

收藏 | 浏览/下载：141/0 | 提交时间：2013/03/25

Method of gain firing data by calculate the group of differential equation has the advantages of high repeatability and high accuracy But much of the CPU time is occupied by the task of re-iteration in computational processing. Therefore it is not the real time processing. This paper introduces a method to quickly determine angle of firing by iteration method which realizes Runge-Kutta method for the equations of exterior ballistic according to the model of mass center motion of projectile. Moreover it also provides the flow of real-time integral solution and be proved by the simulation of MATLAB. Its accuracy satisfies the requirements. This work can be as reference for the design of opt-electrical fire control system and the demonstration work. 2012 IEEE.

Modelling of the electric field assisted capillarity effect used for the fabrication of hollow polymer microstructures (EI CONFERENCE) 会议论文 OAI收割
2012 13th International Thermal, Mechanical and Multi-Physics Simulation and Experiments in Microelectronics and Microsystems, EuroSimE 2012, April 16, 2012 - April 18, 2012, Cascais, Portugal
Tonry C.; Patel M.; Bailey C.; Desmuliez M. P. Y.; Cargill S.; Yu W.

收藏 | 浏览/下载：93/0 | 提交时间：2013/03/25

Electric Field Assisted Capillarity (EFAC) is a novel process which has the potential for the single step fabrication of hollow polymer microstructures. The process has been shown to work experimentally on a microscale level using Polydimethylsiloxane (PDMS). The process makes use of both the electrohydrodynamics of polymer at a microscale and the voltage enhanced capillary force exerted on the polymer. This paper discusses the results of a two-dimensional numerical simulation of this process. The results presented use a patterned master electrode producing encapsulated microchannels in the polymer. The simulations demonstrate how the differing contact angles between the polymer and the walls of the master electrode affect the thickness of the top surface of the formed microstructures. It also specifies the conditions necessary for the successful fabrication of such microstructures. 2012 IEEE.

Design of high speed and parallel compression system used in the big area CCD of high frame frequency (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Precision Engineering and Non-Traditional Machining, PENTM 2011, December 9, 2011 - December 11, 2011, Xi'an, China
作者: Li G.-N.; Jin L.-X.; Zhang R.-F.; Wang W.-H.; Li G.-N.

收藏 | 浏览/下载：51/0 | 提交时间：2013/03/25

According to the area CCD camera of characteristics such as high resolution capacity and high frame frequency this paper puts forward a high speed and parallel image compression system of high integration degree. Firstly according to the work principle of the area CCD FPGA is adopted to realize the timing driving and multichannel and parallel analog signal handling to raise the export frame frequency of the area CCD. Secondly with an image compression scheme based on FPGA embedded processor MicroBlaze and ADV212 compression chip real time image compression and the high speed area CCD are realized. Finally by detecting the analog signal of the area CCD output the real time compression of the big area CCD image is carried out in different compression ratios and the compression performance is analyzed. Experiment result shows that this scheme can realize real time image compression with the biggest data rate of 520Mbps. When compression bit ratio is 0.15 the signal-to-noise ratio of peak value can reach 36 dB. Image collection and image compression are integrated which reduces the data transmission between them and improves systematic integration degree.