检索结果-南通市图书馆

Signal recovery method based on co-prime array

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Engineering and Electronics 2017年第2期28卷 224-234页

作者： Shuang qiu Weixing sheng Xiaofeng Ma Yubing Han Renli Zhang School of Electronic and Optical Engineering Nanjing University of Science and TechnologyNanjing 210094China

A signal waveform recovery method based on the co-prime array is investigated to extract the waveform of the desired signal from spatial interferences in narrowband scenarios. The direction of arrivals (DOAs) of the desired signal and interference signals are estimated with the compressive sensing approach based on angle grids, and the signal power together with the noise power are estimated. Thereafter, a modified steepest descent (SD) method is derived to recover the waveform of the desired signal and interferences utilizing the estimated power and directions. The recovered waveform of the desired signal is the output of the proposed method. The situation in which the signals are not on the predefined angle grids is also considered. The DOAs estimated via the predefined angle grids are corrected based on the maximum likelihood (ML) angle estimation. Compared to the existing beamforming methods on co-prime array, the proposed method can obtain the waveform of the desired signal. Simulation results demonstrate that the proposed method can achieve good performance in signal waveform recovery and output signal to noise ratio. © 2017 Beijing Institute of Aerospace Information.

关键词： Compressed sensing Maximum likelihood Maximum likelihood estimation Recovery Signal reconstruction Signal to noise ratio

Deep Neural Network Closed-loop with Raw Data for Optical Resident Space Object Detection

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第11期24卷 95-103页

作者： He Zhao rong-Yu Sun sheng-Xian Yu Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space Science University of Science and Technology of ChinaHefei 230026China

Optical survey is an important means for observing resident space objects and space situational *** the application of astronomical techniques and reduction method,wide field of view telescopes have made significant contributions in discovering and identifying resident space ***,with the development of modern optical and electronic technology,the detection limit of instruments and infrastructure has been greatly extended,leading to an extensive number of raw images and many more sources in these *** arise when reducing these data in terms of traditional measurement and *** on the amount of data,it is particularly feasible and reliable to apply machine learning *** an end-to-end deep learning framework is developed,it is trained with a priori information on raw detections and the automatic detection task is performed on the new data *** closed-loop is evaluated based on consecutive CCD images obtained with a dedicated space debris survey *** is demonstrated that our framework can achieve high performance compared with the traditional method,and with data fusion,the efficiency of the system can be improved without changing hardware or deploying new *** technique deserves a wider application in many fields of observational astronomy.

关键词： methods data analysis-techniques image processing-surveys

Angiotensinogen gene polymorphism and ischemic stroke in East Asians:A meta-analysis

在线全文

学校读者我要写书评

暂无评论

Neural Regeneration Research 2013年第13期8卷 1228-1235页

作者： sheng Wang rong Zeng Limin Lei Jinsong Huang Department of Anesthesiology Guangdong Cardiovascular Institute Guangdong Academy of Medical Sciences Guangdong General Hospital Department of Cardiovascular Surgery Guangdong Cardiovascular Institute Guangdong Academy of Medical Sciences Guangdong General Hospital

OBJECTIVE： To investigate the association between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians. DATA RETRIEVAL： A computer-based online search was conducted in PubMed, Google scholar, China National Knowledge Infrastructure database between January 1990 and April 2012 for relevant studies. The key words were angiotensinogen or AGT, polymorphism or genetic and ischemic stroke or cerebral infarction. SELECTION CRITERIA： Case-controlled studies addressing the correlation between angiotensinogen gene M235T polymorphism and ischemic stroke in East Asians were included. The distribution of genotypes in the included studies was tested for Hardy-Weinberg equilibrium. Quality evaluation of the included studies was conducted by two physicians. Statistical analyses were carried out using Stata 12.0 software for meta-analysis. Heterogeneity tests, sensitivity analysis and publication bias were also conducted. MAIN OUTCOME MEASURES： The association between angiotensinogen gene M235T polymorphism and ischemic stroke risk in East Asians was assessed. RESULTS： Six relevant studies involving 891 patients with ischemic stroke and 727 controls were included in this meta-analysis. Results showed that there was a significant association between angiotensinogen gene M235T polymorphism and the risk of ischemic stroke in East Asians （T vs. M odds ratio （OR） = 1.54, 95% confidence interval （CI） = 1.10-2.16; TT vs. MM： OR = 2.24, 95%CI = 1.37-3.66; TT vs. MT： OR = 1.76, 95%CI = 1.41-2.20; MM ＋ MT vs. TT： OR = 0.57, 95%CI -= 0.46-0.70）. Sensitivity analysis confirmed that the study results were stable and reliable, with no publication bias. CONCLUSION： The angiotensinogen gene M235T polymorphism is associated with ischemic stroke in East Asians, and the TT genotype and T allele are risk factors for ischemic stroke.

关键词： neural regeneration brain injury cerebrovascular disease angiotensinogen ischemic stroke riskfactor meta-analysis East Asians genetic polymorphism cerebral infarction grants-supportedpaper neuroregeneration

Crossing w=1 in Gauss-Bonnet Brane World with Induced Gravity

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2005年第5X期44卷 948-954页

作者： CAI rong-Gen ZHANG Hong-sheng WANG An-Zhong Institute of Theoretical Physics the Chinese Academy of Sciences P.O. Box 2735 Beijing 100080 China CASPER Department of Physics Baylor University 101 Bagby Avenue Waco TX 76706 USA

Recent type Ia supernovas data seemingly favor a dark energy model whose equation of state w（z） crosses -1 very recently, which is a much more amazing problem than the acceleration of the universe. In this paper we show that it is possible to realize such a crossing without introducing any phantom component in a Gauss-Bonnet brane worm with induced gravity, where a four-dimensional curvature scalar on the brahe and a five-dimensional Gauss-Bonnet term in the bu/k are present. In this realization, the Gauss-Bonnet term and the mass parameter in the bulk play a crucial role.

关键词： dark energy brane world scenario phantom divide

A CLASS OF TWO-STEP CONTINUITY RUNGE-KUTTA METHODS FOR SOLVING SINGULAR DELAY DIFFERENTIAL EQUATIONS AND ITS STABILITY ANALYSIS

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 2005年第6期23卷 647-656页

作者： Xin Leng De-gui Liu Xiao-qiu Song Li-rong Chen Beijing Institute of Computer Application and Simulation Technology 100854 China Beijing Institute of Applied Physics and Computational Mathematics 100088 China

In this paper, a class of two-step continuity Runge-Kutta（TSCRK） methods for solving singular delay differential equations（DDEs） is presented. Analysis of numerical stability of this methods is given. We consider the two distinct cases：（i）τ≥ h, （ii）τ 〈 h, where the delay τ and step size h of the two-step continuity Runge-Kutta methods are both constant. The absolute stability regions of some methods are plotted and numerical examples show the efficiency of the method.

关键词： Analysis of numerical stability Singular delay differential equations Two-step continuity Runge-Kutta methods

Effect of Frequency on Emission of XeI＊ Excimer in a Pulsed Dielectric Barrier Discharge

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2004年第7期21卷 1317-1319页

作者： OUQiong-rong MENGYue-Dong XUXu SHUXing-sheng RENZhao-Xing InstituteofPlasmaPhysics ChineseAcademyofSciencesPOBox1126Hefei230031

Emission spectra of XeI* excimers and ultraviolet intensity at 253nm from a dielectric barrier discharge (DBD) lamp excited by a pulsed voltage were measured as functions of pressure, electrical power, and frequency. In the DBD lamp driven by a higher frequency voltage, a more intense emission of XeI* excimers with high efficiency at 253nm was found. A diffuse discharge mode was observed at high xenon pressure (>1atm) with an excessive iodine concentration in the DBD driven by a high frequency (60kHz) voltage.

关键词： Emission spectroscopy

Further Notes on the Gaussian Beam Expansion

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2012年第2期29卷 116-118页

作者： DAI Yu-rong DING De-sheng Department of Physics Southeast UniversityNanjing 210096 School of Electronic Science and Engineering Southeast UniversityNanjing 210096 Laboratory of Modern Acoustics of MOE Nanjing UniversityNanjing 210093

We provide alternatively a simple way of computing the Fresnel field integral,a further extension to the Gaussianbeam *** a known result that the circ function is approximately decomposed into a sum of Gaussian functions,the zero-order Bessel function of the first kind is similarly expanded by the Bessel-Fourior *** expansions are together inserted in this integral,which is then expressible in terms of the simple algebraic *** approach is useful in treatment of the field radiation problem for a large and important group of piston sources in *** examples,the calculation results for the uniform and the simply supported piston sources are presented,in a good agreement with those evaluated by numerical integration.

关键词： functions Gaussian Bessel

Synthesis and Crystal Structure of 4-Salicyli deneamino-3-methyl-1,2,4-triazol-5-thione

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Structural Chemistry 2003年第5期22卷 529-532页

作者： WENLi-rong LIGuo-Qiang LIMing JINGShu-Xia ZHANGShu-sheng CollegeofLifeScienceandPharmacenticalEngineering NanjingUniversityofTechnologyNanjing210009China CollegeofChemistryandMoleculeEngineering QingdaoUniversityofScienceandTechnologyQingdao266042China NationalLaboratoryofAppliedOrganicChemistry LanzhouUniversityLanzhou730000China

The crystal structure of 4-salicylideneamino-3-methyl-1,2,4-triazol-5-thione 1 (C10H10N4OS, Mr = 234.28) has been determined by single-crystal X-ray diffraction method. The crystal belongs to monoclinic, space group P21/n with a = 12.697(3), b = 7.4072(15), c = 12.750(3) , b = 117.68(3), V = 1061.85(4) 3, Z = 4, Dc = 1.465 g/cm3, m = 0.288 mm-1 and F(000) = 488. R = 0.0584 and wR = 0.1642 for 2660 unique reflections with 2130 observed ones (I > 2s(I)). The results confirmed that the configuration of the title compound at the azomethine C=N bond is E and 1 can be assigned as the thione tautomeric form. All atoms of the title compound are essentially coplanar.

关键词： salicylideneamino-3-methyl-1,2,4-triazol-5-thione crystal structure synthesis

Hidden spin polarization in the 1T-phase layered transition-metal dichalcogenides MX_2(M = Zr, Hf; X = S, Se, Te)

在线全文

学校读者我要写书评

暂无评论

Science Bulletin 2018年第2期63卷 85-91页

作者： Cai Cheng Jia-Tao Sun Xiang-rong Chen sheng Meng Institute of Atomic and Molecular Physics College of Physical Science and Technology Sichuan University Institute of Physics Chinese Academy of Sciences

The recent discovery of hidden spin polarization emerging in layered materials of specific nonmagnetic crystal is a fascinating phenomenon, though hardly explored yet. Here, we have studied hidden spin tex- tures in layered nonmagnetic 1 T-phase transition-metal dichalcogenides MX2 （M = Zr, Hf; X = S, Se, Te） by using first-principles calculations. Spin-layer locking effect, namely, energy-degenerate opposite spins spatially separated in the top and bottom layer respectively, has been identified. In particular, the hidden spin polarization of 13-band can be easily probed, which is strongly affected by the strength of spin-orbit coupling. The hidden spin polarization of k-band locating at high symmetry M point （conduction band minimum） has a strong anisotropy. In the bilayer, the hidden spin polarization is preserved at the upmost Se layer, while being suppressed if the ZrSe2 layer is taken as the symmetry partner. Our results on hidden spin polarization in 1 T-phase dichalcogenides, verifiable by spin-resolved and angle-resolved photoemis- sion spectroscopy （ARPES）, enrich our understanding of spin physics and provide important clues to search for specific spin polarization in two dimensional materials for spintronic and quantum informa- tion applications.

关键词： Hidden spin polarizationTransition-metal dichalcogenides 1T-phaseHelical spin textureCentrosymmetric