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	Constraining the X-Ray-Infrared Spectral Index of Second-timescale Flares from SGR 1935+2154 with Palomar Gattini-IR 期刊论文 OAI收割 The Astrophysical Journal, 2020, 卷号: 901, 页码: L7 作者: HXMT \| 收藏 \| 浏览/下载：27/0 \| 提交时间：2022/02/08 Radio transient sources Magnetars Soft gamma-ray repeaters 2008 992 1471 Astrophysics - High Energy Astrophysical Phenomena Astrophysics - Instrumentation and Methods for Astrophysics Abstract: The Galactic magnetar SGR 1935+2154 has been reported to produce the first example of a bright millisecond-duration radio burst (FRB 200428) similar to the cosmological population of fast radio bursts (FRBs). The detection of a coincident bright X-ray burst represents the first observed multiwavelength counterpart of an FRB. However, the search for similar emission at optical wavelengths has been hampered by the high inferred extinction on the line of sight. Here, we present results from the first search for second-timescale emission from the source at near-infrared (NIR) wavelengths using the Palomar Gattini-IR observing system in the J band, enabled by a novel detector readout mode that allows short exposure times of ?0.84 s with 99.9% observing efficiency. With a total observing time of ?12 hr (?47,728 images) during its 2020 outburst, we place median 3Ҡlimits on the second-timescale NIR fluence of ?18 Jy ms (13.1 AB mag). The corresponding extinction-corrected limit is ?125 Jy ms for an estimated extinction of A_J = 2.0 mag. Our observations were sensitive enough to easily detect an NIR counterpart of FRB 200428 if the NIR emission falls on the same power law as observed across its radio to X-ray spectrum. We report nondetection limits from epochs of four simultaneous X-ray bursts detected by the Insight-HXMT and NuSTAR telescopes during our observations. These limits provide the most stringent constraints to date on fluence of flares at 10¹⁴ Hz, and constrain the fluence ratio of the NIR emission to coincident X-ray bursts to R_NIR ? 0.025 (fluence index ?0.35).
	Low-cost field production of biochars and their properties 期刊论文 OAI收割 ENVIRONMENTAL GEOCHEMISTRY AND HEALTH, 2019 作者: Xiao, L; Feng, LR; Yuan, GD; Wei, J \| 收藏 \| 浏览/下载：29/0 \| 提交时间：2020/07/08 Biowaste Exposure times Functional groups Cadmium Oxytetracycline
	Method of auto multi-exposure for high dynamic range imaging (EI CONFERENCE) 会议论文 OAI收割 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China Piao Y.; Xu W. 收藏 \| 浏览/下载：26/0 \| 提交时间：2013/03/25 This paper proposes a method for calculating the multi-exposure times fast and accurately when the scene has a high dynamic range minimizing the pictures needed to take and improving the dynamic range of the CCD system. The proposed method first measures the camera's response function referring [10]. After that the median value of the output picture is adjusted to be in the middle range of the system output by changing the exposure time. It can be inferred from the histogram of the current picture whether it's a high dynamic range scene by calculating the number of pixels under exposed and over exposed. Once again the under and over exposed pixels are adjusted to be in the middle according to the camera's response function. Finally different exposed pictures (2 or 3) are fused together by Gaussian function and the dynamic range is compressed by y correction. Experimental results on UNIQ-UM400 analog camera and a digital acquisition system show that the algorithm works well and solve the problem of low dynamic range of CCD camera. 2010 IEEE.
	A design on a control method of a new type of focal plane shutter (EI CONFERENCE) 会议论文 OAI收割 2010 International Conference on Computer, Mechatronics, Control and Electronic Engineering, CMCE 2010, August 24, 2010 - August 26, 2010, Changchun, China Xue L.; Ming L.; Zheng L.-N.; Zhou J.-F.; Zhang H.-W.; Zhang J.-C. 收藏 \| 浏览/下载：36/0 \| 提交时间：2013/03/25 In order to ensure appropriate exposure time and no exposure while electric charge is transferring after taking a photograph it is necessary to have the shutter mechanism cooperate with CCD for area CCD aerial cameras. The ground object illumination has a wide range which is from 4000Lx to 100000Lx so a shutter which is high efficient and a continuous stepless adjustment are also required. This paper introduces the fundamental principle structural design and control procedure about this new focal plane shutter. Under the control of DSP the velocity of shutter curtain governed by the shutter motor can be not only precisely controlled but also the durability and the reliability are increased. The experiment results have shown that this new shutter has the higher stability of movement long life span with more than 105 operating times a wide range of exposure time from1/ 50s to 1/ 320s(depending on the slit width)and the exposure error is less than 10%. With the CCD gain adjustment the performance of this shutter is fully satisfied with the requirements of area CCD aerial cameras. 2010 IEEE.
	Modulation transfer function in seeker camera limits resulting from missile flutter caused by aerodynamic force (EI CONFERENCE) 会议论文 OAI收割 2010 2nd International Conference on Industrial Mechatronics and Automation, ICIMA 2010, May 30, 2010 - May 31, 2010, Wuhan, China 作者: Zhang X.; Zhang X.; Zhang X. 收藏 \| 浏览/下载：29/0 \| 提交时间：2013/03/25 The imaging quality of seeker in flight mode has been evaluated through analyzing the effects of missile flutter on optical modulation transfer function (MTF) of the optical system. Firstly the data of transverse vibration has been processed to eliminate the trend term caused by the trajectory then obtained the displacement with two times trapezoidal integration. For the side rotation the high frequency noise interference in the data has been filtered by using five-point moving average method. Took this model as the quivering rule between the object and the image and then analyzed the effects of the transverse vibration and the side rotation on imaging quality through MTF. By calculation the r.m.s value of the image motion caused by missile transverse vibration is 0.026mm and the side rotation angle is 0.0044 . Through the establishment of two modulation transfer functions (MTF) of image random vibration and linear vibration the results show that the image quality had declined and the effect of transverse vibration on image quality is obvious. Through improving the rigidity of the missile and selection of small focal length optical system and shorten the time of exposure can improve the imaging quality of the seeker. 2010 IEEE.
	Micro-motion exposure method based on PZT piezoelectric ceramics (EI CONFERENCE) 会议论文 OAI收割 International Symposium on Photoelectronic Detection and Imaging 2009: Material and Device Technology for Sensors, June 17, 2009 - June 19, 2009, Beijing, China 作者: Meng Z.; Meng Z. 收藏 \| 浏览/下载：106/0 \| 提交时间：2013/03/25 There mainly is laser digital photofinishing technique and digital photofinishing technique based on LCD consisting of TFT and LCOS in the digital photofinishing field at the present time. The former have a good many merit such as wide color gamut high processing rate large output size and high brightness but his cost is very high his maintain technique being comparatively complex that result in difficult use for people. The utilization ratio of the latter is low because of lower resolution and lower aperture ratio for LCD but the digital photofinishing based on LCD have lower cost and higher utilization ration being suitable for people's current standard of living. Considering above mentioned problem a micro-motion exposure method based on PZT piezoelectric ceramics used in digital image photofinishing is presented. The two-dimension micro-motion exposure system consisting of PZT piezoelectric ceramics LCD panel polarizing film and spring strip is designed. By means of PZT piezoelectric ceramics the LCD panel is removed about the one half of the pixel size of the LCD panel for four times from the original place at the same time imaging system is exposed four times at the printing paper. The software is used to control the time synchronization the exposure time and motion range of the LCD panel. The system has advantages such as shorter response time than 0.1seconds lesser motion error than 0.01 microns high stability and repeatability. Experimental results show that the proposed micro-motion exposure method improve the picture brightness and enlarge output size at the meantime reducing the cost of the system. 2009 SPIE.