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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

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收藏 | 浏览/下载：24/0 | 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).

The effect of substrate on powder concentration distribution in coaxial laser cladding 会议论文 OAI收割
23rd International Congress of Theoretical and Applied Mechanics, 中国北京/Beijing, China, 2012-08-19
作者: Liu H(刘昊); Jin SW(靳绍魏); He XL(何秀丽); Yu G(虞钢)

收藏 | 浏览/下载：26/0 | 提交时间：2014/03/19

substrate cladding laser distribution powder coaxial concentration effect thermal nozzle without between large formed enough steady though results search model

A strong coupled CFD-CSD method on computational aeroelastity (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
Xi R.; Jia H.

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In this paper a strong coupled CFD-CSD method is developed to simulate the aeroelastic phenomena. The CFD solver is based on the finite-volume algorithm for the Navier-Stokes equations on unstructured grid. The CSD solver solves the aeroelastic governing equations in the modal space. Their coupling is realized by a dual-time method. The spring-based smoothing method is adopted to deform and regenerate the aerodynamic grid. Two test cases are selected to validate the authors' method for static and dynamic aeroelastity .The results of the simulation for the static aeroelastic problems of a missile wing show that the Lift Coefficient and Drag Coefficient are severally 7% and 5% lower than those don't consider the elasticity of the wing. The results for the flutter boundary prediction of the AGARD 445.6 wing have been proved much closer to the experiment than using the DLM. This method can describe the effects of fluid viscosity more exactly for highly nonlinear transonic flight conditions. The calculation has proved reliable in the subsonic regime but not accurate enough in the supersonic regime. 2011 IEEE.

Reentry guidance based on feedback linearization (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electronics, Communications and Control, ICECC 2011, September 9, 2011 - September 11, 2011, Ningbo, China
Li D.-W.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

This paper presents a new reentry guidance algorithm for RLV (Reusable Launching Vehicle). The algorithm consists of two integrated components: trajectory planning algorithm and tracking algorithm. The most striking feature of algorithm here lies in that both planning and tracking are executed directly in height-velocity space which is different from the methodology of configuration of drag in traditional shuttle guidance. In the session of trajectory planning all trajectory constraints can be expressed with upper bound and lower bound in height-velocity space then a linear interpolation is carried to search the nominal trajectory satisfying the requirement of downrange and target constraints. Then the tracking algorithm uses feedback linearization method to track this nominal profile and meet all constraints. Another typical feature of this algorithm is the strategy of downrange extension using FPA (flight path angle) controller to fulfill the requirement of large downrange. Proper combination of planning-tracking algorithm and FPA controller can bring great flexibility and adaptability to reentry guidance. The algorithm is proved to be robust enough to accommodate the model error and noises in the dynamics. 2011 IEEE.

Performance test of steel tube enclosed thermistors in air temperature measurements (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China
作者: Yang H.; Yan F.; Yan F.; Peng J.

收藏 | 浏览/下载：32/0 | 提交时间：2013/03/25

The performances of two steel tube enclosed precision thermistors are tested in a well controlled air environment to determine if the thermistors have enough accuracy for 0.01C levels of air temperature gradient measurement. Three Fluke's 5641 and three 5610 thermistors were tested for 24 hours in Fluke's 7008 calibration bath in the first step. In the second step the performances of these two thermistors in steady state and transient state air temperature environments were tested for 8 hours separately. The results illustrate that two of the 5641s were airproofed in a temperature well controlled tube when steel tube enclosed precision thermistors are used in air temperature measurement there are unstable departures from each other with a maximum 8.8 mC in constant air medium and 27 mC in temperature changing air medium. The transient-time errors are too large to show the true amounts of temperature changes for air temperature measurement. 2011 IEEE.

Study on spectrograph for ionosphere: A broadband imaging instrument prototype for far-ultraviolet (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Space Exploration Technologies and Applications, May 24, 2011 - May 26, 2011, Beijing, China
作者: Wang S.-R.; Lin G.-Y.; Yu L.

收藏 | 浏览/下载：36/0 | 提交时间：2013/03/25

Current research on space-based exploration for the ionosphere needs more advanced technologies. Because the spectral signals in the ionosphere distributing basically in the far-ultraviolet waveband are very weak. Usual spectrometer structures and detectors such as CCD can't receive enough information. Based on this principle of atmospheric sounding the imaging spectrometer prototype for ionosphere detection application was designed to solve the problem. This prototype consists of the telescope and the imaging spectrometer. The simple structure and small number of mirrors can help higher transmission efficiency be achieved and weak signals detection be implemented. The telescope is an off-axis parabolic mirror and the spectrometer is a modified Czerny-Turner spectral imaging system. Modified Czerny-Turner spectrometer contains a spherical mirror a fixed plane grating and a toroidal mirror. By adjusting the incident angle to the collimating mirror and using toroidal mirror coma and astigmatism were corrected well. We also optimize distances between the grating to the focusing mirror and the focusing mirror to the image plane to improve disadvantages of traditional Czerny-Turner structure. Designed results demonstrate that aberrations are substantially corrected and high image quality can be obtained in broad waveband. The photon counting Wedge-Strip-Anode detector with micro-channel planes as the receiving plane is accepted for the instrument prototype. The other photon counting 2-D detector responding well for weak light such as Cross-Delay line detector and MAMA detector can also be used for detection. The calibration and performances testing system is made of a vacuum system a deuterium lamp a monochrometer and the instrument prototype. Results obtained from the experiment show that the spectral resolution is 2.4 nm and the spatial resolution is 80 m. The other calibration experiments are running. The technology of the spectrometer prototype is important for the research and applications of ionosphere remote sensing. 2011 SPIE.

The new approach for infrared target tracking based on the particle filter algorithm (EI CONFERENCE) 会议论文 OAI收割
International Symposium on Photoelectronic Detection and Imaging 2011: Advances in Infrared Imaging and Applications, May 24, 2011 - May 24, 2011, Beijing, China
作者: Sun H.; Han H.-X.; Sun H.

收藏 | 浏览/下载：60/0 | 提交时间：2013/03/25

Target tracking on the complex background in the infrared image sequence is hot research field. It provides the important basis in some fields such as video monitoring precision and video compression human-computer interaction. As a typical algorithms in the target tracking framework based on filtering and data connection the particle filter with non-parameter estimation characteristic have ability to deal with nonlinear and non-Gaussian problems so it were widely used. There are various forms of density in the particle filter algorithm to make it valid when target occlusion occurred or recover tracking back from failure in track procedure but in order to capture the change of the state space it need a certain amount of particles to ensure samples is enough and this number will increase in accompany with dimension and increase exponentially this led to the increased amount of calculation is presented. In this paper particle filter algorithm and the Mean shift will be combined. Aiming at deficiencies of the classic mean shift Tracking algorithm easily trapped into local minima and Unable to get global optimal under the complex background. From these two perspectives that "adaptive multiple information fusion" and "with particle filter framework combining" we expand the classic Mean Shift tracking framework.Based on the previous perspective we proposed an improved Mean Shift infrared target tracking algorithm based on multiple information fusion. In the analysis of the infrared characteristics of target basis Algorithm firstly extracted target gray and edge character and Proposed to guide the above two characteristics by the moving of the target information thus we can get new sports guide grayscale characteristics and motion guide border feature. Then proposes a new adaptive fusion mechanism used these two new information adaptive to integrate into the Mean Shift tracking framework. Finally we designed a kind of automatic target model updating strategy to further improve tracking performance. Experimental results show that this algorithm can compensate shortcoming of the particle filter has too much computation and can effectively overcome the fault that mean shift is easy to fall into local extreme value instead of global maximum value.Last because of the gray and fusion target motion information this approach also inhibit interference from the background ultimately improve the stability and the real-time of the target track. 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

The research of rigid lapping technique on diamond grating ruling tool (EI CONFERENCE) 会议论文 OAI收割
2010 International Conference on Materials Science and Engineering Science, ICMSES 2010, December 11, 2010 - December 12, 2010, Shenzhen, China
Jirigalantu A.; Bayanheshig; Dong Q. X.

收藏 | 浏览/下载：25/0 | 提交时间：2013/03/25

One of the effective method of improving diamond tool life on rulling large diffraction gratings is developing precise double-cone edged on line edge transfering tool. But traditional died weight or manual lapping technique couldn't meet the precision requirement of on line edge transfering tool. So preliminary studied rigid lapping of diamond grating ruling tool. Choosing traditional BC6063 shaping machine and made a series of alteration on it achieved the automation of lapping process of diamond grating ruling tool. Through lapping grating ruling tool and AFM measurement find that the surface roughness of tool is 1.51nm the radius of tool edge is 160nm edge quality is good enough this verified the feasibility of rigid lapping of diamond grating ruling tool and lay the foundation for developing precision lapping machine. (2011) Trans Tech Publications Switzerland.

Precision detection of CCD splicing based on template matching algorithm (EI CONFERENCE) 会议论文 OAI收割
IEEE 2nd International Conference on Computing, Control and Industrial Engineering, CCIE 2011, August 20, 2011 - August 21, 2011, Wuhan, China
作者: Zhang X.; Zhang X.; Yang L.; Zhang X.; Yang L.

收藏 | 浏览/下载：32/0 | 提交时间：2013/03/25

The remote sensing camera in large field and wide cover needs CCD with enough pixels. But the existing CCD cannot satisfy the practical needs. Therefore several pieces of CCD which has insufficient pixels are spliced to get a long CCD array with plenty of pixels. The precision requirements of CCD splicing are very strict so that the same high accuracies are required in the precision detection of CCD splicing. When detecting precision of CCD splicing the graphical markers with simple geometric structure in the CCD package are selected as templates. The position precision data of the graphical markers in each CCD are obtained using the template matching algorithm. Using the unified objective templates the focal plane which has multi-chip of CCD is detected by template matching algorithm. Experiment results show that the template matching algorithm can enhance the located precision of each CCD to 0.347m. The splicing precision detection with template matching algorithm can avoid the subjective error caused by the conventional detection method. And its results are more accurate. In addition without manual intervention in the process of precision detection the efficiency of precision detection is improved. 2011 IEEE.

Applying observer feedback in motor control (EI CONFERENCE) 会议论文 OAI收割
3rd International Conference on Measuring Technology and Mechatronics Automation, ICMTMA 2011, January 6, 2011 - January 7, 2011, Shanghai, China
Huan Z.-Y.; Li H.-W.

收藏 | 浏览/下载：11/0 | 提交时间：2013/03/25

When the speed is low or the encoder has a low precision speed measured by backward difference method has obvious truncation error. This will arise ripple in the control system speed response. Speed filtering can decrease the ripple but it's not good enough and it also induces lag. A speed feedback method based on all-state observer was introduced to improve the speed feedback performance. Experiment results show that compared to filtering method the control system performance is improved.