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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.

The braking index of PSR B0540-69 and the associated pulsar wind nebula emission after spin-down rate transition 期刊论文 OAI收割
Monthly Notices of the Royal Astronomical Society, 2020, 卷号: 494, 页码: 1865-1870
作者: HXMT

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stars: magnetic field stars: neutron pulsars: general Astrophysics - High Energy Astrophysical Phenomena Abstract: In 2011 December, PSR B054-69 experienced a spin-down rate transition (SRT), after which the spin-down power of the pulsar increased by $\sim 36{{\ \rm per\ cent}}$. About 1000 d after the SRT, the X-ray luminosity of the associated pulsar wind nebula (PWN) was found to brighten by $32\pm 8{{\ \rm per\ cent}}$. After the SRT, the braking index n of PSR B0540-69 changes from n = 2.12 to 0.03 and then keeps this value for about five years before rising to n = 0.9 in the following years. We find that most of the current models have difficulties in explaining the measured braking index. One exceptive model of the braking index evolution is the increasing dipole magnetic field of PSR B0540-69. We suggest that the field increase may result from some instabilities within the pulsar core that enhance the poloidal component at the price of toroidal component of the magnetic field. The increasing dipole magnetic field will result in the X-ray brightening of the PWN. We fit the PWN X-ray light curve by two models: one assumes a constant magnetic field within the PWN during the brightening and the other assumes an enhanced magnetic field proportional to the energy density of the PWN. It appears that the two models fit the data well, though the later model seems to fit the data a bit better. This provides marginal observational evidence that magnetic field in the PWN is generated by the termination shock. Future high-quality and high-cadence data are required to draw a solid conclusion.

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.

Transitional compensation algorithm for correcting non-uniformity of LED display image (EI CONFERENCE) 会议论文 OAI收割
2012 2nd International Conference on Materials Science and Information Technology, MSIT 2012, August 24, 2012 - August 26, 2012, Xi'an, Shaan, China
Su W.-x.; Chen Y.-s.

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In order to solve the problem of high non-uniformity of LED display images which is caused by the edges of LED display panel during module splicing transitional compensation algorithm is proposed by improving the existed correction technique named the correction technique based on CCD. First introduce the three development stages of the LED display panel. Then the realization progress of the transitional compensation algorithm is described in detail after elaborating the principle of transitional compensation. Finally the algorithm is emplaned in a LED video control system to control the LED display panel whose display area is 1280960 and which is spliced by 3020 LED modules whose size are 6432. Experimental results show that this algorithm is able to reduce non-uniformity of LED display images from 29.3% before correcting to 0.95%. (2012) Trans Tech Publications Switzerland.

Influence of high temperature annealing in nitrogen on upconversion luminescence of -NaYF4: Yb3+, Er3+ hexagonal sub-microplates (EI CONFERENCE) 会议论文 OAI收割
2012 International conference on Function Materials and Nanotechnology, FMN 2012, May 19, 2012 - May 20, 2012, Zhengzhou, China
作者: Zhao J.

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The pure -NaYF4: Yb3+ Er3+ hexagonal sub-microplates were successfully prepared by the combination of coprecipitation and hydrothermal methods using sodium citrate as chelator. The size of them is about 600 nm 400 nm (side length thickness). The obtained sample was divided into two parts and one of them was annealed in nitrogen at 300 C for 2 hours. The crystal structure of the -NaYF4: Yb3+ Er3+ hexagonal sub-microplates before and after annealing treatment is hexagonal phase. Under the excitation of 980 nm diode laser the upconversion luminescence intensity the sample after annealing is much stronger than that of the sample without annealing treatment. High temperature annealing process improved the crystallization of the sample resulting in the decrease of the nonradiative relaxation and the enhancement of the upconversion luminescence. (2012) Trans Tech Publications Switzerland.

Design and image restoration research of a cubic-phase-plate system (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, April 26, 2010 - April 29, 2010, Dalian, China
作者: Zhang J.; Zhang J.; Zhang J.; Shi G.; Zhang X.

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Wave-front coding technology is a novel jointly optical and digital imaging technology which can greatly extend the depth of focus of optical systems. The image restoration process is an important part of wave-front coding technology. Using wave-front coding makes the modulation transfer function(MTF) values of the optical systems change little over a range of several times the depth of focus which means the system MTF is quite insensitive to defocus and there is no zero in the passband. So we can design a single filter for the restoration of images in different defocus positions. However it's hard to avoid noise during image acquisition and transmission processes. These noises will be amplified in the image restoration especially in the high frequency part when the MTF drop is relatively low. The restoration process significantly reduces the system signal to noise ratio this way. Aimed at the problem of noise amplification a new algorithm was proposed which incorporated wavelet denoising into the iterative steps of Lucy-Richardson algorithm. Better restoration results were obtained through the new algorithm effectively solving the noise amplification problem of original LR algorithm. Two sets of identical triplet imaging systems were designed in one of which the cubic-phase-plate was added. Imaging experiments of the manufactured systems were carried and the images of a traditional system and a wave-front coded system before and after decoding were compared. The results show that the designed wave-front coded system can extend the depth of focus by 40 times compared with the traditional system while maintaining the light flux and the image plane resolution. 2010 Copyright SPIE - The International Society for Optical Engineering.

Instability of seabed and pipes induced by NGH dissociation 会议论文 OAI收割
20th International Offshore and Polar Engineering Conference, ISOPE-2010, Beijing, China, June 20, 2010 - June 25, 2010
作者: Lu XB(鲁晓兵); Li QP; Wang L; Zhang XH(张旭辉); Yao HY

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Before and after Elastic parameters NGH Numerical modeling Practical engineering

非晶硅薄膜制备及其晶化特性研究 期刊论文 OAI收割
人工晶体学报, 2008, 卷号: 37, 期号: 5, 页码: 1191, 1194
罗士雨; 冯磊; 汪洪; 林辉; 滕浩; 黄涛华; 周圣明

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磁控溅射 Amorphous silicon films 非晶硅 Annealing temperatures 多晶硅 Before and after Crystallization properties K9 glasses Low temperatures Polycrystalline silicon Raman spectrums Scattering peaks Si films

The effect of N/Si ratio on the a-SiiH/SiNx interface of a-SirH/SiNx TFT (EI CONFERENCE) 会议论文 OAI收割
Asia Display 2007, AD'07, March 12, 2007 - March 16, 2007, Shanghai, China
Liu J. e.; Gao W.; Liao Y.; Jing H.; Fu G.

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The threshold voltage of a-Si: H/SiNx TFT will shift under long time gate bias stress it is mostly leaded by charge trapping in gate insulator and defect creation in semiconductor. And it is hard to be applied in AMOLED for TFT because of its threshold voltage shift. In allusion to the phenomenon of charge trapping a series of SiNx insulating films in different N/Si(0. 87 -1.68) ratio were deposited by PECVD in this paper controlling different flow ratio of source gas SiH4 and NH3 and a great deal of tests (ellipsometer infrared absorption (FTIR) and Electron Dispersion Spectrum (EDS) test ) were done on these samples. Based on these SiNx insulators three different capacitance samples in MIS structure were done degraded experiments and C-V tests on these samples were done. The C-V curve shift of capacitance which contained SiNx with slightly N-rich(N/Si is bigger slightly than 1. 33) was not evident before and after degradation this result indicated that the defect density of this type SiN x was smaller and could restrain charge chapping in the interface of a-Si:H/SiNx effectively. So that as gate insulator of TFT SiN x with slightly N-rich could decrease the threshold voltage shift of TFT and enhance its stability effectively.

Intersectant multi-target serial number fuzzy match by multi-parameters (EI CONFERENCE) 会议论文 OAI收割
ICO20: Optical Information Processing, August 21, 2005 - August 26, 2005, Changchun, China
作者: Wang Y.-J.

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In order to match the intersectant targets' tab when these objects separate a kind of method that makes use of fuzzy multi-parameter to match targets is proposed. Multi-parameters include the forecasted position after targets separate target speed target size and geometry shape and different parameter corresponds to different influence coefficient evaluate the integrated matching coefficient that every observation target corresponds to forecasted target and the corresponding relationship that matching coefficient is the biggest is the best matching result. In order to locate the position and speed of forecasted target a new method of track forecast is proposed firstly Hough transform is used to the object's track before objects intersect by this the object's positions that the warp between forecasted location and observation location is large enough is eliminated then least square method is used for track forecast by the remainder valid positions and get hold of the forecasted position when objects separate. The experiment results show: when tracking the bulky objects which intersect and separate the right identification probability of traditional least square method is 87.5% and the right identification probability of fuzzy match by multi-parameters can attain 96% the reliability improves in evidence.