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No pulsed radio emission during a bursting phase of a Galactic magnetar 期刊论文 OAI收割
Nature, 2020, 卷号: 587, 页码: 63-65
作者: HXMT

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Astrophysics - High Energy Astrophysical Phenomena Abstract: Fast radio bursts (FRBs) are millisecond-duration radio transients of unknown physical origin observed at extragalactic distances^1-3. It has long been speculated that magnetars are the engine powering repeating bursts from FRB sources^4-13, but no convincing evidence has been collected so far¹⁴. Recently, the Galactic magnetar SRG 1935+2154 entered an active phase by emitting intense soft íray bursts¹⁵. One FRB-like event with two peaks (FRB 200428) and a luminosity slightly lower than the faintest extragalactic FRBs was detected from the source, in association with a soft íray/hard-X-ray flare^18-21. Here we report an eight-hour targeted radio observational campaign comprising four sessions and assisted by multi-wavelength (optical and hard-X-ray) data. During the third session, 29 soft-íray repeater (SGR) bursts were detected in íray energies. Throughout the observing period, we detected no single dispersed pulsed emission coincident with the arrivals of SGR bursts, but unfortunately we were not observing when the FRB was detected. The non-detection places a fluence upper limit that is eight orders of magnitude lower than the fluence of FRB 200428. Our results suggest that FRB-SGR burst associations are rare. FRBs may be highly relativistic and geometrically beamed, or FRB-like events associated with SGR bursts may have narrow spectra and characteristic frequencies outside the observed band. It is also possible that the physical conditions required to achieve coherent radiation in SGR bursts are difficult to satisfy, and that only under extreme conditions could an FRB be associated with an SGR burst.

Accuracy synthesis of a 3-RPS parallel robot based on manufacturing costs (EI CONFERENCE) 会议论文 OAI收割
31st Chinese Control Conference, CCC 2012, July 25, 2012 - July 27, 2012, Hefei, China
Yao T.-K.; Xi Z.; Feng Z.; Zhang L.-M.; Yong W.

收藏 | 浏览/下载：32/0 | 提交时间：2013/03/25

Pose accuracy is an important issue for parallel robot being used as mirror supporting system of telescope. One challenging topic is the accuracy synthesis which deals with the optimal design of the manufacturing and assembling tolerances of each component under the given pose accuracy. First the error model of the 3-RPS parallel robot is built based on total derivation of the kinematic equations. And the error variable of each spherical or rotate joint can be expressed as a single boundary error parameter but not three independent position parameters. Then the accuracy synthesis model is formulated taking the manufacturing costs as the optimization objective and the accuracy requirements as the constraint condition. Finally the genetic algorithm is used to solve the optimization problem and a simulation example is given. The results show that the accuracy synthesis method based on manufacturing costs can satisfy the need of pose accuracy and is better for engineering application than the method based on error sensitivity. 2012 Chinese Assoc of Automati.

Design of the real-time autofocusing system for collimator with long focus length and large aperture (EI CONFERENCE) 会议论文 OAI收割
2011 International Academic Conference on Numbers, Intelligence, Manufacturing Technology and Machinery Automation, MAMT 2011, December 24, 2011 - December 25, 2011, Wuhan, China
作者: Zhang X.; Zhang X.; Zhang X.

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Large aperture collimator which has been widely used for calibrating and testing various optical devices plays an essential role in correlative laboratories. As being the basic testing and calibration equipment the large aperture collimator's accuracy should be much higher than the device under testing in order to ensure the accuracy of the measurement. However the process of adjusting the collimator is extremely complicated due to the collimator's large aperture and long focal length. So it is difficult to ensure the measurement's quality and easy to cause the system being vulnerable to the surrounding environment. One of the most common problems is defocus. In order to solve the problem above this issue presents a new type of autocollimator autofocusing system which uses pentaprism instead of using large-aperture plane mirror semiconductor lasers as light source and CCD sensor as receiver. The system is smaller lighter and more convenient when using. The computer simulation shows that the autofocusing system's resolution could reach the accuracy of 40m. If we use the relevant algorithms to execute the sub-pixel scanning the resolution could reach the accuracy of 10m. It shows that the system could satisfy the required testing precision of testing large aperture optical device.

An auto-focus algorithm of fast search based on combining rough and fine adjustment (EI CONFERENCE) 会议论文 OAI收割
3rd international Conference on Manufacturing Science and Engineering, ICMSE 2012, March 27, 2012 - March 29, 2012, Xiamen, China
作者: Zhang S.; Zhang Y.

收藏 | 浏览/下载：28/0 | 提交时间：2013/03/25

A coarse and fine combined fast search and auto-focusing algorithm was suggested in this paper. This method can automatically search and find the focal plane by evaluating the image definition. The Krisch operator based edge energy function was used as the big-step coarse focusing and then the wavelet transform based image definition evaluation function which is sensitivity to the variation in image definition was used to realize the small-step fine focusing in a narrow range. The un-uniform sampling function of the focusing area selection used in this method greatly reduces the workload and the required time for the data processing. The experimental results indicate that this algorithm can satisfy the requirement of the optical measure equipment for the image focusing. (2012) Trans Tech Publications.

Optimum design of laser encoding and decoding on laser beam-riding guidance (EI CONFERENCE) 会议论文 OAI收割
2nd International Conference on Frontiers of Manufacturing and Design Science, ICFMD 2011, December 11, 2011 - December 13, 2011, Taichung, Taiwan
作者: Yang L.; Yang L.

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Operating principle of laser beam-riding guidance was set forth. Based on the principle of spatial frequency-encoding experimental results demonstrated that the receiver can receive correctly the encoded signal and can decode the signal an optimum laser encoding mode was designed measurement for the missdistance is feasible and all the performance parameters satisfy the demand. (2012) Trans Tech Publications which can transfer continuous laser into pulse laser that represents different position information. Then the mathematic model of deviation from target is built Switzerland. a modified encoding pattern was presented which is composed of two light paths crossed 90. Azimuth information of target is given in orthogonal coordinate system and deviation from target is linearity. As well as characteristic distribution of spatial laser field is analyzed. Corresponding decoding mode was presented by testing in 2 kilometers outdoor

The parameter optimization of missile actuator based on spatial RSSR linkage mechanism (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Electric Information and Control Engineering, ICEICE 2011, April 15, 2011 - April 17, 2011, Wuhan, China
Ge M.; Han X.; Jia H.

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Analyzed the forms of movement of missile actuator based on spatial RSSR linkage mechanism. To achieve synchronic output of each axis applied the multi-body dynamic application ADAMS to realize its parametric modeling and optimization finally got the appropriate parameters to satisfy the performance. Then researched the parameters affection to synchronic performance completed the initial design of the actuator transmission system. 2011 IEEE.

The design of analog video data grabber system based on TMS320VC33 and SAA7111A (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
作者: Liu S.-J.

收藏 | 浏览/下载：15/0 | 提交时间：2013/03/25

Analog video data grabber system based on TMS320VC33 and SAA7111A is proposed for a kind of automatic optical alignment measuring device. System uses the enhanced video processing chip SAA7111A to complete A/D conversion. The function of SAA7111A and the register configuration method of I2C Bus are introduced in the paper. System uses FPGA to control video data grabber and collaborative work of DSP. DSP processes video data. The paper gives design method of hardware and software. Experimental results indicate that the system can satisfy the requirements. 2011 IEEE.

Study on the servo system of large telescope based on the internal model pid control strategy (EI CONFERENCE) 会议论文 OAI收割
IEEE 2011 10th International Conference on Electronic Measurement and Instruments, ICEMI 2011, August 16, 2011 - August 18, 2011, Chengdu, China
Li H.

收藏 | 浏览/下载：21/0 | 提交时间：2013/03/25

This paper developed the internal model PID control for large telescope control system considerations in more parameters adjustment in servo control loop at present. The large electro-optic telescope system belongs to a big inertia system. This simplifies the debug process the feasibility and robustability are also verified by the analyses and simulation results that satisfy the high precision demand. The practicability of this algorithm is verified in an actual project that only two parameters need adjusted. The application shows that this system runs stably with high accuracy. The technology and methods adopted in the system are practical and worthy of using abroad. 2011 IEEE.

The structure design and analysis of predigest laser combine bind and extend bind flat roof (EI CONFERENCE) 会议论文 OAI收割
2011 International Conference on Advanced Engineering Materials and Technology, AEMT 2011, July 29, 2011 - July 31, 2011, Sanya, China
作者: Wang B.; Wang H.; Wang H.; Wang H.; Wang H.

收藏 | 浏览/下载：31/0 | 提交时间：2013/03/25

This paper put forward a kind of predigest laser combine bind and extend bind flat roof structure which is founded as fission flat roof and can be built in an little room 1280mm990mm815mm. This flat roof space location can be adjusted. This kind of seat can ensure the system complete laser combine and close as high precision. In this paper we designed the laser combine and close whole structure and install design. At last we did some finite statics analysis to some important parts. This design can ensure every laser fire directional adjust mete lower 30' and the flat roof quality is 770kg. The transition benchmark flat roof system most meet and emergency is 0.005mm at the premise of bear the weight of turn flat laden. It can be seen that this structure can satisfy the request of many lasers small space laser extend bind and adjust. This kind can be extended to other light combine bind and extend bind structure design. (2011) Trans Tech Publications Switzerland.

Compensation of moire fringe sinusoidal deviation in photoelectrical encoder based on tunable filter (EI CONFERENCE) 会议论文 OAI收割
2011 Symposium on Photonics and Optoelectronics, SOPO 2011, May 16, 2011 - May 18, 2011, Wuhan, China
作者: Wang Y.; Wang Y.; Wang Y.

收藏 | 浏览/下载：30/0 | 提交时间：2013/03/25

In order to improve the precision of the absolute photoelectrical encoder a compensating method is put forward which restrains the harmonics in moire fringe signal. After analyzing the relationship between the subdividing error and the sinusoidal index a low-pass digital filter which can make the moire signal satisfy the need of 1024 subdivision is designed. Considering with the fundamental frequency varies with the rotating speed of encoder the tunable filter is adopted whose cutoff frequency is calculated according to the coarse information of the encoder. The simulating results show that the proposed method can improve the sinusoidal index especially at high rotating speed. At last the compensating algorithm is implemented in the terminal of satellite optical communication which needs high resolution. The experimental results show indicate that the developed method is feasible. 2011 IEEE.