中国科学院机构知识库网格系统: 检索

浏览/检索结果: 共8条，第1-8条

帮助

条数/页：排序方式：
	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).
	Study on medical X-ray coherent scatter imaging and processing based digital flat detector (EI CONFERENCE) 会议论文 OAI收割 3rd International Conference on BioMedical Engineering and Informatics, BMEI 2010, October 16, 2010 - October 18, 2010, Yantai, China 作者: Li B.; Zhao J.; Li B.; Li B.; Liu J. 收藏 \| 浏览/下载：32/0 \| 提交时间：2013/03/25 It is introduced a novel imaging technique for medical diagnostic X-ray coherent scatter in this paper. A set of experimental equipment for X-ray coherent scatter imaging was set up with X-ray digital flat detector and medical diagnostic X-ray source. According to this equipment the scatter images obtained are made of some circles with the same center. It is vital to calculate the energy template to classify the different samples. It is difficult to separate them using the traditional threshold method due to noise and overlapped shadow. In this paper the image was transformed a binary image by using K-Means algorithm and Mathematical Morphology Methods. The effective region was extracted from the binary image inside the orthogonal energy projection space then to calculate the centroid of rings. Consequently the curve of the energy distribution was built. The experiment results show that our method is reasonable and feasible. The technique will have wide foreground of application .Besides the imaging of human bone content it can be used for various imaging of tissue and organs in biology. 2010 IEEE.
	An 8-channel, area-efficient, low-power audio sampling rate converter (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: Liu Y.; Liu Y.; Liu Y.; Wang D. 收藏 \| 浏览/下载：28/0 \| 提交时间：2013/03/25 A novel 8-channle third area-efficient next a new Timing Division Multiplexer (TMD) scheme lowers clock working rate to minimum in order to save power a novel memory addressing scheme reduces 20% data memory at least. Experiments show proposed methods could not only saved hardware resources but also reduce power consumption low-power audio sampling rate converter is proposed in this paper so it is very suitable for consumer electronics. 2009 IEEE. conversion ratio is 2:1 and 4:1. Filter design and implementation are the key points for the converter. First excluded data and coefficients memories adopting multiplier-free Arithmetic Unit (AU) and rounding methods allows its realization in a cell area of only 0.038mm 2 in 0.18 m technology
	A multi-channel, area-efficient, audio sampling rate interpolator (EI CONFERENCE) 会议论文 OAI收割 2009 8th IEEE International Conference on ASIC, ASICON 2009, October 20, 2009 - October 23, 2009, Changsha, China 作者: Wang D. 收藏 \| 浏览/下载：26/0 \| 提交时间：2013/03/25 The area and power consumption of sampled rate converter are governed largely by associated digital interpolationfilters. This paper presents a novel multi-channel area-efficient audio sampling rate interpolator whose conversion ratio is 1:2 and 1:4. Several architectural and implementation features reduces the complexity of the filter and allow its realization in a die area of 0.032mm2 in 0.18 m technology meanwhile timing multiplexer scheme reduces clock frequency to minimum. Experiments show proposed methods could not only saved hardware resources but also reduce power consumption so it is very suitable for consumer electronics. 2009 IEEE.
	Force spectroscopy of single receptor-ligand bond using an optical trap 会议论文 OAI收割 2009 Asia Communications and Photonics Conference and Exhibition, ACP 2009, Shanghai, China, November 2, 2009 - November 6, 2009 作者: Zhang Y(章燕); Sun GY(孙淦云); Li N(李宁); Huo B(霍波); Lv SQ(吕守芹) 收藏 \| 浏览/下载：16/0 \| 提交时间：2017/07/14 Bond dissociation Force spectroscopy Low loading Novel methods Optical trap Receptor-ligand bonds Receptor-ligand interactions Thermal fluctuations Unbinding transitions
	A MLP-PNN neural network for CCD image super-resolution in wavelet packet domain (EI CONFERENCE) 会议论文 OAI收割 2008 International Conference on Wireless Communications, Networking and Mobile Computing, WiCOM 2008, October 12, 2008 - October 14, 2008, Dalian, China Zhao X.; Fu D.; Zhai L. 收藏 \| 浏览/下载：68/0 \| 提交时间：2013/03/25 Image super-resolution methods process an input image sequence of a scene to obtain a still image with increased resolution. Classical approaches to this problem involve complex iterative minimization procedures typically with high computational costs. In this paper is proposed a novel algorithm for super-resolution that enables a substantial decrease in computer load. First decompose and reconstruct the image by wavelet packet. Before constructing the image use neural network in place of other rebuilding method to reconstruct the coefficients in the wavelet packet domain. Second probabilistic neural network architecture is used to perform a scattered-point interpolation of the image sequence data in the wavelet packet domain. The network kernel function is optimally determined for this problem by a MLP-PNN (Multi Layer Perceptron - Probabilistic Neural Network) trained on synthetic data. Network parameters dependent on the sequence noise level. This super-sampled image is spatially Altered to correct finite pixel size effects to yield the final high-resolution estimate. This method can decrease the calculation cost and get perfect PSNR. Results are presented showing the quality of the proposed method. 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.
	A micro diffuser/nozzle pump with fins on the sidewall 会议论文 OAI收割 4th International Conference on Solid-State Sensors, Actuators and Microsystems, TRANSDUCERS and EUROSENSORS '07, Lyon, France, June 10, 2007 - June 14, 2007 作者: Li XH; Yu XM; Zhang DC; Li ZH; Xu WH 收藏 \| 浏览/下载：20/0 \| 提交时间：2017/06/01 Diffuser/nozzle Diffuser/nozzle pump Fins Flow efficiency International conferences Key parts Novel methods Pump performance Silicon micro-machining Solid-state sensors