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Detection of Flare Multiperiodic Pulsations in Mid-ultraviolet Balmer Continuum, Lyl Hard X-Ray, and Radio Emissions Simultaneously 期刊论文 OAI收割
The Astrophysical Journal, 2021, 卷号: 921, 页码: 179
作者: HXMT

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收藏 | 浏览/下载：25/0 | 提交时间：2022/02/08

Solar flares Solar oscillations Solar ultraviolet emission Solar x-ray emission Solar radio emission 1496 1515 1533 1536 1522 Astrophysics - Solar and Stellar Astrophysics Abstract: Quasi-periodic pulsations (QPPs), which usually appear as temporal pulsations of the total flux, are frequently detected in the light curves of solar/stellar flares. In this study, we present the investigation of nonstationary QPPs with multiple periods during the impulsive phase of a powerful flare on 2017 September 6, which were simultaneously measured by the Hard X-ray Modulation Telescope (Insight-HXMT), as well as the ground-based BLENSW. The multiple periods, detected by applying a wavelet transform and Lomb-Scargle periodogram to the detrended light curves, are found to be ~20-55 s in the Ly`and mid-ultraviolet Balmer continuum emissions during the flare impulsive phase. Similar QPPs with multiple periods are also found in the hard X-ray emission and low-frequency radio emission. Our observations suggest that the flare QPPs could be related to nonthermal electrons accelerated by the repeated energy release process, i.e., triggering of repetitive magnetic reconnection, while the multiple periods might be modulated by the sausage oscillation of hot plasma loops. For the multiperiodic pulsations, other generation mechanisms could not be completely ruled out.

黄土高原不同恢复年限和降水梯度下人工刺槐林土壤水分时空动态 学位论文 OAI收割
北京: 中国科学院大学；中国科学院生态环境研究中心, 2020
作者: 陈维梁

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收藏 | 浏览/下载：15/0 | 提交时间：2022/06/09

黄土高原土壤水分恢复年限降水梯度湿润锋 (I.e., Hp, Zjy And Rjt, 10-30%) Were Significantly Higher Than That Of The North Plots

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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收藏 | 浏览/下载：48/0 | 提交时间：2022/02/08

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.

The study of encoding principle and encoding disc design of a new-style vernier absolute encoder (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.

收藏 | 浏览/下载：27/0 | 提交时间：2013/03/25

To satisfy the requirement of encoder miniaturization high dependability and high measuring accuracy a new-style vernier absolute type encoder which offered significant advantages over less reticling circles and high precision was presented in the paper which carried out the design of vernier encoding disc the analysis of new-style vernier encoding principle and exact encoding track calibration by studying the photoelectric encoder. The Matlab simulation results prove that the encoding and coding methods are feasible. The test showed that the cubage of encoder was quite small and the diameter of the encoder can be controlled within 100mm its resolution can reach 24 bits i.e. 0.0772. The feasibility of encoding and coding method was further proved. 2011 IEEE.

A fast and efficient multiple step algorithm of iris image quality assessment (EI CONFERENCE) 会议论文 OAI收割
2010 2nd International Conference on Future Computer and Communication, ICFCC 2010, May 21, 2010 - May 24, 2010, Wuhan, China
Shi C.; Jin L.

收藏 | 浏览/下载：15/0 | 提交时间：2013/03/25

Iris recognition is one of the most reliable methods of biometrics personal identification. Poor quality iris image will be rejected by recognition system which will result in the failure of recognition. Therefore iris image quality assessment is very essential to the iris recognition system. In this paper a multiple step algorithm of iris image quality assessment is proposed to distinguish two kinds of poor quality images i.e. defocus and occlusion. Experimental results show that the proposed algorithm is fast and efficient for iris image quality assessment. 2010 IEEE.

Pre-process technique study of a high performance remote image sensor structural Finite Element Analysis (EI CONFERENCE) 会议论文 OAI收割
2010 2nd International Conference on Computer Engineering and Technology, ICCET 2010, April 16, 2010 - April 18, 2010, Chengdu, China
作者: Zhang L.; Xu Y.-S.; Zhang L.

收藏 | 浏览/下载：26/0 | 提交时间：2013/03/25

High precision structural Finite Element Analysis (FEA) results are required in the development of a remote image sensor. HperMesh and MSC. Nastran are employed in the image sensor structural FEA. This paper discusses some technical issues about the Finite Element (FE) modeling of the image sensor. In order to obtain authentic analysis results the part-to-whole handling schema i.e. handling method and research work is implemented in a small part of the model firstly and a revised method is used in the whole structural in succession has been proposed. Some emphasis is mainly put on the FE handling of bolted joint bearing and inter-element connection. The interface handling methods such as CBEAM plus partial MPC bolted joint model hybrid element bearing model and RBE3 beam-to-solid connection have been produced and successfully implemented in the image sensor structural FEA. 2010 IEEE.

Analysis of spectrum narrowing of diode laser bar (EI CONFERENCE) 会议论文 OAI收割
Semiconductor Lasers and Applications III, November 12, 2007 - November 13, 2007, Beijing, China
作者: Liu Y.; Wang L.; Wang L.; Wang L.; Liu Y.

收藏 | 浏览/下载：18/0 | 提交时间：2013/03/25

Laser diode bar (LDB) are used increasingly often for many applications but spectral bandwidth of LDB are generally approximately 2-4nm far too wide for many demanding applications e.g. spin-exchange optical pumping terahertz generation and lidar. External-cavity feedback can improve the spectral properties of LD or LDB. However spectrum narrowing of LDB is more difficult than that of LD. Bar curvature (i.e. "smile") produced in the manufacturing process affects the spectrum narrowing greatly. By geometrical optics approach and ORIGIN software smile which can be corrected by plano-convex cylindrical lens is simulated and the result is in good agreement with experiment. The selection of grating which is also a critical factor of spectrum narrowing will be stated. Finally an external cavity consisting of fast axis collimator two plano-convex cylindrical lens and a diffraction grating is used. The scheme is implemented on a 19-element LDB and yields 3-fold reduction in spectral linewidth under the situation that all optical elements in the system which are not optimized. Further we use a slit in the experiment and analyze the spectrum narrowing of each element in LDB.

Heterogeneous architecture-based software reliability estimation: Case study (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on Convergence and Hybrid Information Technology, ICCIT 2008, November 11, 2008 - November 13, 2008, Busan, Korea, Republic of
Wei Y.; Shen X.-H.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

With growing system complication multiple structures are constructed in software instead of single architecture style. As a result the traditional architecture-based models that have considered only homogeneous software behaviors are not suitable to the complex system. In this paper a heterogeneous architecture-based model is presented. In order to verify the practicability we apply the model to estimate the system reliability of the astronautics payload communication and monitoring system (APCMS). Multiple structures are constructed in the system i.e. sequence parallel and fault-tolerance. The study results demonstrate that the model is accurate when compared to the actual reliability. Theoretical research must be applied on actual systems to understand their applicability and accuracy. 2008 IEEE.

Study of high precision non-contact measurement based on CCD (EI CONFERENCE) 会议论文 OAI收割
4th International Conference on Information Technology and Applications, ICITA 2007, January 15, 2007 - January 18, 2007, Harbin, China
Lin L.; Yun F.

收藏 | 浏览/下载：22/0 | 提交时间：2013/03/25

In this paper a method that measures relatively positionrelationshipquickly and accurately between two vehicles both on a horizontal plane is introduced. When the linear CCD camera placed on the end of manipulator scans two point targets located on the other vehicle by virtue of the spatial intersection principle and trigonometry theorem the relative position relationship between the loading vehicles and launching ones can be gotten(i.e. the spatial coordinate parameters of x y z and the angle displacement ). At the same time the paper establishes that the measurement error of length is less than 1mm by analysis of thee rror analysis and the simulation of computer. The angle displacement is less than 3 which satisfies the technical requests. So the vehicle orientation and loading missiles can be both done at the shortest time. It meets the demand of centralization between the measurement and execution. Forboth automatic transshipment and spatial position relationship measurement the study is valuable. And the manipulator is measure device as well as executive one so that residual inherent error decreases according to identical reference principle. Therefore the measure precision can be improved greatly.

Fabrication of polysilicon thin film on glass with low-temperature UV-assisted crystallization (EI CONFERENCE) 会议论文 OAI收割
ICO20: Display Devices and Systems, August 21, 2005 - August 26, 2005, Changchun, China
Huang J. Y.; Ling Z. H.; Jing H.; Fu G. Z.; Zhao Y. H.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

The amorphous silicon (a-Si) film was crystallized on glass by a simple method employed ultraviolet at temperatures as low as 400C. The employ of ultraviolet enhanced the crystallization of amorphous silicon. This method is able to uniformly crystallized large-area amorphous silicon films. The polysilicon films crystallized by this way are suitable for the fabrication of thin film transistors on ordinary glass. Crystallization process is performed in a furnace. Amorphous silicon sample is placed on a hot plate and irradiated by a bank of ultraviolet lamps through a diffuser plate to improve the uniformity of light that irradiates the sample. Raman microscopy is used for analyzing the qualities of UV-assisted crystallized silicon films. By measuring the Raman spectra the effects of anneal temperature and process time on the crystallizing behavior crystallinity and grain size of the processed films were obtained. There has a threshold temperature for crystallization of amorphous silicon film in the presence of ultraviolet irradiation with certain intensity i.e. by ultraviolet irradiation with certain intensity only when the temperature is up to the threshold temperature the crystallization can be triggered. The threshold temperature is 400C when the intensity of ultraviolet irradiation is 1mW/cm2. Above threshold temperature the increase of anneal temperature increased the rate of crystallization. Crystallinity and grain size extracted from Raman spectra of samples increase with the extending of process time at certain temperature. Crystallization of amorphous silicon film with thickness of 50nm completed within 6 hours at 400C irradiated by ultraviolet with intensity of 2mW/cm2.