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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 \| 收藏 \| 浏览/下载：58/0 \| 提交时间：2022/02/08 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.
	Smoothed estimator of quantile residual lifetime for right censored data 期刊论文 OAI收割 JOURNAL OF SYSTEMS SCIENCE & COMPLEXITY, 2015, 卷号: 28, 期号: 6, 页码: 1374-1388 作者: Zhang Li; Liu Peng; Zhou Yong \| 收藏 \| 浏览/下载：27/0 \| 提交时间：2018/07/30 Empirical process estimating equation influence curve Kaplan-Meier estimator kernel smoothing quantile residual lifetime right censored data
	Comparison of radiation temperature measurement precision between middlewave and longwave thermal-imaging systems (EI CONFERENCE) 会议论文 OAI收割 2012 International Conference on Optoelectronics and Microelectronics, ICOM 2012, August 23, 2012 - August 25, 2012, Changchun, China 作者: Sun Z. 收藏 \| 浏览/下载：28/0 \| 提交时间：2013/03/25 A comparison study on temperature measurement precision between middlewave 3-5m and longwave 8-12m measuring thermal imaging systems has been conducted. The study was limited to systems working in indoor conditions and the target's temperature is in the range of 270K900K. First the Disturb Resisting Function (DRF) of infrared systems is deduced. On the base of DRF curve we find that the middlewave infrared system get the smaller influences under the same size disturb compared with the longwave system. A theory of the influence of target's physical characteristic and measurement conditions on the accuracy of temperature measurements has been developed. On the basis of the developed formulas an analysis of the influence of signal disturbances (because of incorrectly assumed emissivity limited transmittance of the atmosphere radiation reflected by the object and shift of optics radiation) on the accuracy of temperature measurement has been made. It has been found that the middlewave systems in typical temperature range offer generally better accuracy in temperature measurement than the longwave ones do. 2012 IEEE.
	The application of template matching arithmetic on Strap-down North Seeking System (EI CONFERENCE) 会议论文 OAI收割 2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011, August 19, 2011 - August 22, 2011, Jilin, China Li D.-N.; Zhu W.; Chen T. 收藏 \| 浏览/下载：18/0 \| 提交时间：2013/03/25 In order to solve the problem of self-determination directional of theodolite equipment based on dynamically tuned gyroscope is proposed. The principle of the Multi-position Strap-down North Seeking System is introduced. Mathematical model of the system is discussed. The factors that influence the precision are analyzed. In order to fit the curve of sampling data back-propagation neural network arithmetic is used in data processing. As templates curve model is saved at database of the VC software. The template matching arithmetic advanced the measure precision of this system. The measure time of the system is shortened within 1 minute so it can save time for theodolite. 2011 IEEE.
	The Research of real time auto-recognition of the moire fringe (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Imaging Detectors and Applications, May 24, 2011 - May 26, 2011, Beijing, China Wang M.-J.; Wu Z.-G. 收藏 \| 浏览/下载：19/0 \| 提交时间：2013/03/25 Measuring the movement of raster by the method of moire fringe has the advantage of high sensitivity high resolution and non-contacted measurement. The characteristic of moire fringe is that the image is white alternate with black the angle of the stripes is uniform the width of the stripes is uniform the terminators of the stripes aren't clear. A fast method that can figure out the width and angle of the moire fringe precisely is put forward in this paper. It calculates the angle the stripes firstly. According to the principle of the minimum mean squared error (MMSE) the closer a series of data is the smaller the value of the MMSE will be. The method is described as follows: It takes the image's center as the origin 180 beelines pass through the origin with the same angle interval. it calculates the value of the minimum mean squared error of the 180 beelines and find out the least one among those then the angle of the moire fringe comes out primarily. In order to improving the calculating precision of moire fringe 60 equal angles are divided in the neighborhood of the angle then a precise angle of moire fringe is calculated according to the principle of the MMSE. After getting out the angle of the moire fringe we begin to calculate the width of moire fringe. A line vertical with the moire fringe is drawn and we can get the width of the moire fringe by the vertical line. In order to get over the influence of the noise an effective area with the shape of diamond is selected in the image. The data of area is accumulated and projected according to the direction of moire fringe and a sine curve come out. The width of moire fringe can be obtained by getting the position of the first wave crest the position of the last wave crest and the number of wave crest. Experiments prove that the precision of the method put forward in this paper is enhanced in comparison with the traditional frequency method the precision of width calculation achieves to 99.6% according to the evaluation indicators of width detection error. The computing speed is boosted largely compared with traditional method and it can achieve with 15 ms that satisfying the demand of real time. 2011 SPIE.
	Graph fitting test method for the interpolation error of Moire fringe (EI CONFERENCE) 会议论文 OAI收割 9th International Conference on Electronic Measurement and Instruments, ICEMI 2009, August 16, 2009 - August 19, 2009, Beijing, China 作者: Sun Y.; Sun Y. 收藏 \| 浏览/下载：30/0 \| 提交时间：2013/03/25 In order to realize the fast test for the interpolation error the graph fitting test method for the interpolation error of Moire fringe is put forward in this paper. Firstly the triangular wave Moire fringe photoelectric signal of the encoder whose phase difference is 90 are sampled to get the Lissajous graph of the two signals. Secondly the single wave represented by the founded subsection function is used to fit the practical Moire fringe Lissajous graph. Then the fitting result is tested to verify whether it satisfies the accuracy requirement. Lastly the founded subsection function instead of the practical wave function is used to calculate the interpolation error. Using the graph fitting method to sample the Moire fringe single of 15-bits photoelectric encoder to get the interpolation error curve the tested maximum interpolation error is 70" and the minimum error is - 69". Comparing with the interpolation error which is received from traditional test method the change trend of the interpolation error curve is similar and peak-peak value is almost equality. The results of experiment indicate that: the equipment is convenient and the examination method is efficient and feasible. The measure speed is fast and the manifestation result is intuitionistic. The system can be used in the working field. The method can avoid the speed influence and realize the dynamic interpolation error measure which is significant for the research of encoder's dynamic accuracy characteristics. 2009 IEEE.
	Study and calibration of azimuth effect in multi-position strap-down north seeking system (EI CONFERENCE) 会议论文 OAI收割 7th World Congress on Intelligent Control and Automation, WCICA'08, June 25, 2008 - June 27, 2008, Chongqing, China 作者: Wang Z.; Zhao J.; Wang Z. 收藏 \| 浏览/下载：10/0 \| 提交时间：2013/03/25 In order to reduce the influence of azimuth effect in multi-position strap-down north seeking system its cause of formation is studied based on the precession principle of the dynamically tuned gyro. A detecting system composed by true north prism two Leica theodolites and benchmark prism fixed in the strap-down north seeking system was designed to calibrate the azimuth effect. By two steps many measurements are gone on in every position to eliminate the random error. According to the homologous between the error and the position a sinusoid is made a fit as compensate curve after the error of twelve positions is measured. Then the azimuth effect of the arbitrary position can be corrected by the curve. The experiment result shows that the seeking north standard deviation is only 11.77 after compensation which is considerably less than the 87.75 without correction. 2008 IEEE.
	Novel fast measurement method of twist angle and optical retardation of liquid crystal display (EI CONFERENCE) 会议论文 OAI收割 Asia Display 2007, AD'07, March 12, 2007 - March 16, 2007, Shanghai, China Huang X.; Lu Y.-T.; Kong X.-J.; Jing H.; Fu G.-Z.; Jin H. 收藏 \| 浏览/下载：15/0 \| 提交时间：2013/03/25 A novel method is proposed to measure twist angle and optical retardation of liquid crystal display in this paper. The new method which is one of single-wavelength methods has three characteristics introducing a method of measuring the total intensity ratio of the transmitted light to eliminate the influence of absorption by the polarizer using circularly and homogeneously aligned LC cell (CH-LC) as a unique polarization-converting device analyzer using variable sector diaphragm and photodetector to detect the total intensity of transmitted light whose original polarization direction is continuously changed from 0 to arbitrary angle CH-LC liquid crystal display and so on. The twist angle () and optical retardation (nd) can be derived by using Jones matrix analysis and a curve fitting where and nd are fitting parameters. Experiment proved the results are accurate the process of operation is fast the devices are economical.