中国科学院机构知识库网格系统: 检索

浏览/检索结果: 共6条，第1-6条

帮助

条数/页：排序方式：
	Real-time temperature estimation method for electromagnetic performance improvement of a large axisymmetric radio telescope under solar radiation 期刊论文 OAI收割 Iet Microwaves Antennas & Propagation, 2020, 卷号: 14, 期号: 13, 页码: 1635-1642 作者: Lian, Peiyuan; Wang, Congsi; Xu, Qian; Xiang, Binbin; Shi, Yu \| 收藏 \| 浏览/下载：44/0 \| 提交时间：2021/06/25 radiotelescopes temperature sensors reflector antennas solar radiation temperature database table look-up method temperature field estimation speed real-time estimated temperature field temperature sensors real-time compensation axisymmetric telescopes time temperature estimation method electromagnetic performance improvement axisymmetric radio telescope solar radiation electromagnetic performances EM performance improvements temperature simulation fast estimation method transient temperature field simulation high-frequency radio telescopes large-aperture radio telescopes reflector antenna reflector antennas surface error adjustment pattern field Engineering Telecommunications
	GNSS time offset monitoring based on the single difference among systems 期刊论文 OAI收割 IET RADAR SONAR AND NAVIGATION, 2020, 卷号: 14, 期号: 2, 页码: 299-302 作者: Tu, Rui; Zhang, Pengfei; Zhang, Rui; Fan, Lihong; Liu, Jinhai \| 收藏 \| 浏览/下载：24/0 \| 提交时间：2020/11/09 delays satellite navigation radio receivers Global Positioning System GNSS time single difference time offset monitoring multiple Global Navigation Satellite Systems compatibility interoperability conventional signal space approaches single-point positioning SPP precise point positioning single-difference point positioning SDPP receiver clock parameter common model errors estimated time smooth estimation time offset estimation different stations system biases
	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：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).
	Multi-focus image fusion algorithm based on adaptive PCNN and wavelet transform (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 Wu Z.-G.; Wang M.-J.; Han G.-L. 收藏 \| 浏览/下载：78/0 \| 提交时间：2013/03/25 Being an efficient method of information fusion image fusion has been used in many fields such as machine vision medical diagnosis military applications and remote sensing.In this paper Pulse Coupled Neural Network (PCNN) is introduced in this research field for its interesting properties in image processing including segmentation target recognition et al. and a novel algorithm based on PCNN and Wavelet Transform for Multi-focus image fusion is proposed. First the two original images are decomposed by wavelet transform. Then based on the PCNN a fusion rule in the Wavelet domain is given. This algorithm uses the wavelet coefficient in each frequency domain as the linking strength so that its value can be chosen adaptively. Wavelet coefficients map to the range of image gray-scale. The output threshold function attenuates to minimum gray over time. Then all pixels of image get the ignition. So the output of PCNN in each iteration time is ignition wavelet coefficients of threshold strength in different time. At this moment the sequences of ignition of wavelet coefficients represent ignition timing of each neuron. The ignition timing of PCNN in each neuron is mapped to corresponding image gray-scale range which is a picture of ignition timing mapping. Then it can judge the targets in the neuron are obvious features or not obvious. The fusion coefficients are decided by the compare-selection operator with the firing time gradient maps and the fusion image is reconstructed by wavelet inverse transform. Furthermore by this algorithm the threshold adjusting constant is estimated by appointed iteration number. Furthermore In order to sufficient reflect order of the firing time the threshold adjusting constant is estimated by appointed iteration number. So after the iteration achieved each of the wavelet coefficient is activated. In order to verify the effectiveness of proposed rules the experiments upon Multi-focus image are done. Moreover comparative results of evaluating fusion quality are listed. The experimental results show that the method can effectively enhance the edge details and improve the spatial resolution of the image. 2011 SPIE.
	Affine object recognition and affine parameters estimation based on covariant matrix (EI CONFERENCE) 会议论文 OAI收割 2008 International Symposium on Information Science and Engineering, ISISE 2008, December 20, 2008 - December 22, 2008, Shanghai, China 作者: Wang Y.; Wang Y.; Wang Y.; Wang Y.; Wang Y. 收藏 \| 浏览/下载：140/0 \| 提交时间：2013/03/25 A new method of affine object recognition and affine parameters estimation is presented. For a real-time image and a group of templates in addition firstly on the basis of correct recognition we segment the object regions in them and compute their covariant matrices. Secondly it can estimate affine parameters exactly normalize the ellipse regions defined by covariant matrices to circle regions to get rotational invariants and the estimated error is within 3%. 2008 IEEE. and compute the similarity function value between rotational invariants of real-time image and every template respectively. Then compare the values with threshold set in advance if more than one value is larger than threshold take the corresponding templates as candidates and compute affine matrix between real-time image and every candidate. Finally transform the realtime image with every affine matrix and match the result with corresponding candidate by classical matching methods. Experimental results show that the presented method is robust to illumination with low computational complexity and it can realize recognition of different affine objects
	Design of GPS/INS integrated navigation system based on multisensor information fusion (EI CONFERENCE) 会议论文 OAI收割 6th World Congress on Intelligent Control and Automation, WCICA 2006, June 21, 2006 - June 23, 2006, Dalian, China Chunmei H.; Yantao T.; Wanxin S.; Mao L. 收藏 \| 浏览/下载：38/0 \| 提交时间：2013/03/25 Two kinds of design methods of GPS/INS integrated navigation system are presented that is GPS/INS integrative system and integrated navigation system based on information fusion. By analyzing mathematics model of the first system error we found that inertia velocity error would cause code loop track error. Consequently the pseudo range meterage error is interrelated with inertia velocity error which is complex to calculate. If this relativity is ignored in the state equation and observation equation of this system it must affect the estimated precision of the kalman filter and maybe the system is unstable. Therefore the second integrated navigation method is introduced. It adopts information fusion federal kalman filter and covariance. And consider the above pertinence to analyze the navigation performance of the integration system. Then it gives the flow of federal kalman filter algorithm. By analyzing the conclusion is that velocity error of integrated navigation system drops from 0.5m/s to below 0.05m/s and improves the precision and reliability of the navigation system effectively well continuity and real-time capability. It provides an effective way for data analysis and process of fusion navigation system. 2006 IEEE.