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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.

Research on the key technology of ATP system for free space optical communication (EI CONFERENCE) 会议论文 OAI收割
31st Chinese Control Conference, CCC 2012, July 25, 2012 - July 27, 2012, Hefei, China
Meng H.; Liu X.; Zhang B.

收藏 | 浏览/下载：20/0 | 提交时间：2013/03/25

Free space optical communication is the bidirectional transmission technology that puts to use the laser beam as a carrier in space. Free space optical communication is generally used in the severe space environment. It is the mainly problem that the narrow beam of laser beam is high-precision aimed. and it is became very important that the technology of ATP is researched. Performance of the ATP system directly affects the performance of the quality of the free space optical communication. So research of the ATP is the key technology in FSO and this technology is discussed and analysed in the article. 2012 Chinese Assoc of Automati.

Analysis on the influence of random vibration on MEMS gyro precision and error compensation (EI CONFERENCE) 会议论文 OAI收割
2011 3rd International Conference on Mechanical and Electronics Engineering, ICMEE 2011, September 23, 2011 - September 25, 2011, Hefei, China
作者: Li M.

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In order to improve its precision in dynamic environment a Kalman filter was designed. Firstly two sets of random drift data of MEMS gyro were respectively analysed and it was found that the variance of random drift under random vibration significantly increased and its mean also changed. Then calculation results show that attitude angle error under random vibration is 2.6 while in the static test it is 0.25. Analysis on the characteristics of random drift was carried out and it is found that it can be treated as stable normally distributed random signal. Finally a corresponding Kalman filter was designed. The results indicated that after filtering the variance of random drift is reduced to 0.0282 26.4% of pre-filtering and the attitude angle error is reduced to 1.5 57.7% of pre-filtering. The above method can effectively compensate for the attitude angle error of MEMS gyro caused by random vibration. This study can be a reference to the application of low-cost MEMS gyro in aircraft navigation. (2012) Trans Tech Publications Switzerland.

Adaptive control at launching using three loop autopilot (EI CONFERENCE) 会议论文 OAI收割
2011 2nd International Conference on Mechanic Automation and Control Engineering, MACE 2011, July 15, 2011 - July 17, 2011, Inner Mongolia, China
作者: Zhang Y.

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In order to guarantee the precise initial flight trajectory control the missile disturbance of large disturbance torque three loop adaptive autopilot was researched. The characteristics of the projectile and three loop autopilot instruction formation characteristics were analysed. From equivalent pitching angle of lateral acceleration feedback loop combined with the instruction of generalized error autopilot structure was simplified and three loop autopilot adaptive control law and stability were designed. The test data show that when disturbance torque was 600Nm the attitude angle generalized error was -4.4. In the time lasted about 15s late trajectory accuracy was within 1.0.Three loop autopilot adaptive control law was able to control the disturbance of initial trajectory and adapt to dynamic characteristics changes control system stability. It was the initial trajectory accurate solution method of flight. 2011 IEEE.

An autostereoscopic projecting system based on parallax barrier and lenticular sheets (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Multimedia Technology, ICMT 2011, July 26, 2011 - July 28, 2011, Hangzhou, China
Kong L.; Jin G.; Zhong X.

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In order to realize autostereoscopic 3D projecting display with higher brightness and larger size a technique of autostereoscopic 3D projecting using parallax barriers and lenticular sheets is proposed.The parameter design of lenticular sheets and parallax barriers is investigated.First projection distance of projector array is confirmed according to eye's resolution then the strips' character of lenticular sheets is analysed by zemax in four-view situation thickness and parameters of strips of lenticular sheets are confirmed. Finally the width of slit and pitch and viewing distance and etc of parallax barriers are confirmed according to parameters of strips of lenticular sheets.Data analysis indicate that the brightness of our four-view image is increased three times because of using lenticular sheets instead of parallax barriers comparing with the autostereoscopic 3D projector using two parallax barriers plates.Parameters design of parallax barriers and lenticular sheets are finished the feasibility and advantages of the 3D display of projecting are confirmed theoretically. 2011 IEEE.

Earth elevation map production and high resolution sensing camera imaging analysis (EI CONFERENCE) 会议论文 OAI收割
Optoelectronic Imaging and Multimedia Technology, October 18, 2010 - October 20, 2010, Beijing, China
作者: Dai L.

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The Earth's digital elevation which impacts space camera imaging has prepared and imaging has analysed. Based on matching error that TDI CCD integral series request of the speed of image motion statistical experimental methods-Monte Carlo method is used to calculate the distribution histogram of Earth's elevation in image motion compensated model which includes satellite attitude changes orbital angular rate changes latitude longitude and the orbital inclination changes. And then elevation information of the earth's surface from SRTM is read. Earth elevation map which produced for aerospace electronic cameras is compressed and spliced. It can get elevation data from flash according to the shooting point of latitude and longitude. If elevation data between two data the ways of searching data uses linear interpolation. Linear interpolation can better meet the rugged mountains and hills changing requests. At last the deviant framework and camera controller are used to test the character of deviant angle errors TDI CCD camera simulation system with the material point corresponding to imaging point model is used to analyze the imaging's MTF and mutual correlation similarity measure simulation system use adding cumulation which TDI CCD imaging exceeded the corresponding pixel horizontal and vertical offset to simulate camera imaging when stability of satellite attitude changes. This process is practicality. It can effectively control the camera memory space and meet a very good precision TDI CCD camera in the request matches the speed of image motion and imaging. 2010 SPIE.

New LED illumination optical engine for micro-projection display (EI CONFERENCE) 会议论文 OAI收割
5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optoelectronic Materials and Devices for Detector, Imager, Display, and Energy Conversion Technology, April 26, 2010 - April 29, 2010, Dalian, China
作者: Meng Z.; Meng Z.

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A new optical engine consisting of LEDs rectangular CPC rectangular lens array and micro display chip DMD is designed by using of KOLA illumination algorithm for micro-projection display. Detail description and analysis of the rectangular CPC and rectangular lens array are provided. The influence due to the size of rectangular CPC and rectangular lens array is analysed for illuminance uniformity on the DMD chip and light energy efficiency of the optical engine system by software ZEMAX. Based on the analysis of parameter of rectangular lens array the size of rectangular lens array more decrease the illumination uniformity. Experimental results show that the proposed illumination light optical engine can obtain perfect rectangular focula with higher light uniformity more than 90 % and higher energy efficiency of 40 % to meet the needs of micro-projection display at the same time the designed illumination optical engine compared with other uniformizing light algorithm have advantages such as: lesser capacity high illumination uniformity. 2010 Copyright SPIE - The International Society for Optical Engineering.

Study on the calculation and application for asphericity of rectangle off-axis aspherics (EI CONFERENCE) 会议论文 OAI收割
4th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Advanced Optical Manufacturing Technologies, November 19, 2008 - November 21, 2008, Chengdu, China
作者:

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Asphericity which affects the manufacturing process and the grinding quantity is an important parameter of optical aspherics. In this paper the approximation the least square fitting wavefront aberration sag methods are given for the calculation of optical asphericity. The effects of different definitions of optical asphericity are analysed to optimize the process of manufacture. A sag method is presented to solve the best-fit sphere and asphericity for an off-aixs aspheric mirror with a rectangle aperture of 180mm145mm and polishing quantity and distribution plots are given. The optical manufacturing and testing technology for different choices of best-fit spheres and asphericity are described and analyzed. Therefore proper definition of optical asphericity which is useful to manufacturing is very important for optical fabrication and test. 2009 SPIE.

Influence of the TDI CCD camera takes pictures when high resolution satellite lateral swaying (EI CONFERENCE) 会议论文 OAI收割
2009 IEEE International Conference on Mechatronics and Automation, ICMA 2009, August 9, 2009 - August 12, 2009, Changchun, China
作者: Zhang L.; Zhang L.; Sun Z.

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When the satellite was swinging and taking lateral imaging the TDI CCD pixel photovoltaic charge purses transferred velocity not matched with the image motion velocity. According to the requirement of high-resolution satellite which was taking lateral imaging at a low orbit the factors that bring about the unmatched phenomenon were analysed inclusive of the Earth's rotation the Earth curvature satellite attitude change measurement error and the installation error etc. Image motion errors caused by various factors were analysed and solved and the different characters of image motion errors were synthesized. Finally the total errors on the impact of imaging system MTF was analyzed. 2009 IEEE.

Configuring an electrostatic membrane reflector with potentials exerted on distributed electrodes (EI CONFERENCE) 会议论文 OAI收割
2009 IEEE International Conference on Mechatronics and Automation, ICMA 2009, August 9, 2009 - August 12, 2009, Changchun, China
作者: Zhang P.; Shi G.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

Electrostatic membrane reflector (EMR) is very promised for optical quality application with the merits of utra-lightweight and flexible. Configuring a circular membrane reflector with electrostatic potentials exerted on distributed electrodes can approximatively produce a parabolic shape. A 300mm EMR (made from polyimide) stretched by distributed electrodes below is designed and the number of concentric electrodes needed for membrane shape forming is analysed. First based on an analytical solution of Poisson's equation determine the membrane control matrix by finding influence functions of 3 concentric electrodes and 6 control points on membrane surface in order to compute the needed voltages exerted on the distributed electrodes by the method of least-squares fitting. Then the final shape solved by finite element analysis with ANSYS is contrasted with the paraboloid and deviates greatly when the central displacement of membrane is beyond 2.5mm but in this range increasing the number of electrodes and control points will get a better shape. The corresponding errors are analyzed and the control method is concluded. Only using the integrated method of analytical computation numerical analysis and experiment the membrane shape of certain central displacement can be exactly predicted and controlled. 2009 IEEE.