检索结果-南通市图书馆

Design and fabrication of erbium doped photosensitive fibers

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2009年第5期52卷 1234-1241页

作者： LI Jian LIU Peng LU ShaoHua WANG Jing mao xiangqiao WEI Huai FU YongJun ZHENG Kai NING TiGang LI TangJun JIAN ShuiSheng Institute of Lightwave Technology Beijing Jiaotong UniversityBeijing 100044China Key Lab of All Optical Network&Advanced Telecommunication Network of EMC Beijing Jiaotong UniversityBeijing 100044China Physics Department of XingTai College Xingtai 054001China

A kind of erbium doped photosensitive fiber(EDPF) was proposed and fabricated,whose core was made of double layers named photosensitive layer and erbium doped *** double-layer core de-sign can overcome difficulties in fabrication of EDPF with single core design,*** conflict between the high consistency rare earth doping and high consistency germanium doping.A sample was fabri-cated through the modified chemical vapor deposition method combined with solution doping *** peak absorption coefficient was 48.80 dB/m at 1.53 μm,the background loss was lower than 0.1 dB/m,and the reflectivity of the fiber Brag gratings(FBG) written directly on the sample fiber was up to 97.3% by UV-writing ***,a C band tunable fiber laser was fabricated using the sample fiber,in which a uniform FBG was written directly on EDPFs as a reflector.A single wavelength lasing with a maximum wavelength tuning range of 1555.2―1558.0 nm was achieved *** this tuning range,the full-width at half maximum(FWHM) of the laser output was smaller than 0.015 nm and the side mode suppression ratio(SMSR) was better than 50 dB.

关键词： erbium doped fiber(EDF) photosensitivity modified chemical vapor deposition(MCVD) method solution doping technique fiber Bragg grating(FBG) fiber laser wavelength tunable

Simulation and evaluation study of atmospheric aerosol nonsphericity as a function of particle size

在线全文

学校读者我要写书评

暂无评论

Particuology 2024年第7期90卷 281-291页

作者： Qianjun mao Xin Nie School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China College of New Energy and Materials Northeast Petroleum UniversityDaqing163318China

Aerosol nonsphericity causes great uncertainty in radiative forcing assessments and climate *** considerable studies have attempted to quantify this uncertainty,the relationship between aerosol nonsphericity and particle size is usually not considered,thus reducing the accuracy of the *** this study,a coupled inversion algorithm combining an improved stochastic particle swarm optimization algorithm and angular light scattering is used for the nonparametric estimation of aerosol nonsphericity variation with particle size,and the optimal sample selection method is employed to screen the *** on the verification of inversion accuracy,the variation of aerosol aspect ratio with particle size based on the ellipsoidal model in global regions has been obtained from Aerosol Robotic Network(AERONET)data,and the effect of nonsphericity on radiative forcing and dry deposition has been *** results show that the aspect ratio increases with particle size in all regions,with the maximum ranging from 1.4 to 1.8 in the desert,reflecting the differences in aerosol composition at different particle *** radiation calculations,considering aerosol nonsphericity makes the aerosol cooling effect weaker and surface radiative fluxes increase,but hardly changes the aerosol absorption,with maximum differences of 9.22%and 22.12%at the bottom and top of the atmosphere,***,the differences in radiative forcing between aspect ratios as a function of particle size and not varying with particle size are not significant,averaging less than 2%.Besides,the aspect ratio not varying with particle size underestimates the deposition velocity of small particles and overestimates that of large particles compared to that as a function of particle size,with maximum differences of 7%and 4%,respectively.

关键词： Aerosol nonsphericity Inversion Aspect ratio Radiative forcing Dry deposition velocity

Pressure-induced hydrogen-dominant high-temperature superconductors

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第7期11卷 14-16页

作者： Ho-kwang mao Shanghai Advanced Research in Physical Sciences Center for High Pressure Science and Technology Advanced Research

Recent studies of hydrogen-dominant（superhydride） materials have led to putative discoveries of near-room temperature superconductivity at high pressures. The idea started more than half-a-century ago as a by-product of the quest for metallic hydrogen for which a natural consequence of its very high Debye temperature and phonon frequency due to the very low mass of the hydrogen atoms would lead to a high superconducting critical temperature （Tc） in weak coupling Bardeen-Cooper-Schrieffer（BCS） expression.

关键词： HYDRIDE LANTHANUM

Proof of Two Supercongruences of Truncated Hypergeometric Series_(4)F_(3)

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第4期40卷 1015-1028页

作者： Guo Shuai mao Department of Mathematics Nanjing University of Information Science and TechnologyNanjing 210044P.R.China

In this paper,we prove two supercongruences conjectured by Z.-*** via the Wilf-Zeilberger *** of them is,for any prime p>3,4F3[7/6 1/2 1/2 1/2 1/6 1 1]-1/8]-1/2≡p(-2/p)+p^(3)/4(2/p)Ep-3 (mod p^(4))where(·/p)stands f... 详细信息

关键词： Supercongruence truncated hypergeometric series Wilf–Zeilberger method Euler numbers Legendre symbol

One bird,multiple stones:The race to find a gene of dominant negative effect in wheat

在线全文

学校读者我要写书评

暂无评论

The Crop Journal 2024年第4期12卷 951-952页

作者： Long mao State Key Laboratory of Crop Gene Resources and Breeding Institute of Crop SciencesChinese Academy of Agricultural SciencesBeijing 100081China

In the current issue of The Crop Journal,Chen et al.[1]reports map-based cloning of a wheat gene that showed temperaturedependent pleiotropic effects on multiple traits including plant height,leaf shape,spike and grain morphology,and accordingly was named WPA1 for Wheat Plant Architecture *** mutant was first observed among EMS-treated plants and repeatedly appeared in multiple occasions.

关键词： Wheat bird repeatedly

Dynamic steric confinement effect expands the frontier of Cu-catalyzed asymmetric propargylic aminations

在线全文

学校读者我要写书评

暂无评论

Science China Chemistry 2024年第10期67卷 3181-3183页

作者： Peng Chen mao-mao Zhang Wen-Jing Xiao Liang-Qiu Lu Engineering Research Center of Photoenergy Utilization for Pollution Control and Carbon Reduction Ministry of EducationCollege of ChemistryCentral China Normal UniversityWuhan 430079China Wuhan Institute of Photochemistry and Technology Wuhan 430082China State Key Laboratory for Oxo Synthesis and Selective Oxidation Lanzhou Institute of Chemical Physics(LICP)Chinese Academy of SciencesLanzhou 730000China School of Chemistry and Chemical Engineering Henan Normal UniversityXinxiang 453007China

Chiralα-tertiary amines and related azacycles are commonly found in many natural products,pharmaceuticals and agrochemicals[1].Copper-catalyzed asymmetric propargylic amination(APA)reactions have been established as a reliable method to access enantio-enriched propargylic amines,largely due to the seminal contribution of Nishibayashi et al.[2]and van Maarseveen et al.[3]in 2008.

关键词： catalyzed asymmetric amines

Heat Storage Performance of PCM in a Novel Vertical Pointer-Shaped Finned Latent Heat Tank

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2024年第2期33卷 422-434页

作者： mao Qianjun ZHU Yuanyuan LI Tao School of Urban Construction Wuhan University of Science and TechnologyWuhan430065China

The heat storage performance of latent heat storage systems is not good due to the poor thermal conductivity of phase change *** this paper,a new type of pointer-shaped fins combining rectangular and triangular fins has been employed to numerically simulate the melting process in the heat storage tank,and the fin geometry parameter effects on heat storage performance have been *** results indicate that compared with the bare tube and the rectangular finned tank,the melting time of the phase change material in the pointer-shaped finned tank is reduced by 64.2%and 15.1%,*** closer the tip of the triangular fin is to the hot wall,the better the heat transfer *** optimal height of the triangular fin is about 8 *** the number of fins from 4 to 6 and from 6 to 8 reduces the melting time by 16.0%and 16.7%***,increasing the number of fins from 8 to 10 only reduces the melting time by 8.4%.When the fin dimensionless length is increased from 0.3 to 0.5 and from 0.5 to 0.7,the melting time is shortened by 17.5%and 13.0%.But the melting time is only reduced by 2.9%when the dimensionless fin length is increased from 0.7 to *** optimising the design of the thermal storage system,the results can provide a reference value.

关键词： thermal energy storage phase change material pointer-shaped fins heat storage performance

Equilibrium Strategy of the Pursuit-Evasion Game in Three-Dimensional Space

在线全文

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第2期11卷 446-458页

作者： Nuo Chen Linjing Li Wenji mao School of Artificial Intelligence University of Chinese Academy of SciencesBeijing 100049 Institute of Automation Chinese Academy of SciencesBeijing 100190China

The pursuit-evasion game models the strategic interaction among players, attracting attention in many realistic scenarios, such as missile guidance, unmanned aerial vehicles, and target defense. Existing studies mainly concentrate on the cooperative pursuit of multiple players in two-dimensional pursuit-evasion games. However, these approaches can hardly be applied to practical situations where players usually move in three-dimensional space with a three-degree-of-freedom control. In this paper,we make the first attempt to investigate the equilibrium strategy of the realistic pursuit-evasion game, in which the pursuer follows a three-degree-of-freedom control, and the evader moves freely. First, we describe the pursuer's three-degree-of-freedom control and the evader's relative coordinate. We then rigorously derive the equilibrium strategy by solving the retrogressive path equation according to the Hamilton-Jacobi-Bellman-Isaacs(HJBI) method, which divides the pursuit-evasion process into the navigation and acceleration phases. Besides, we analyze the maximum allowable speed for the pursuer to capture the evader successfully and provide the strategy with which the evader can escape when the pursuer's speed exceeds the threshold. We further conduct comparison tests with various unilateral deviations to verify that the proposed strategy forms a Nash equilibrium.

关键词： Differential game equilibrium strategy pursuit-evasion game threedegree-of-freedom control

First Passage Density of Brownian Motion with Two-sided Piecewise Linear Boundaries

在线全文

学校读者我要写书评

暂无评论

Acta Mathematica Sinica,English Series 2024年第6期40卷 1505-1520页

作者： Zhen YU mao Zai TIAN Center for Applied Statistics School of StatisticsRenmin University of ChinaBeijing 100872P.R.China School of Mathematics and Data Science Changji UniversityChangji 831100P.R.China

The first passage time has many applications in fields like finance,econometrics,statistics,and ***,explicit formulas for the first passage density have only been obtained for a few *** paper derives an explicit formula for the first passage density of Brownian motion with twosided piecewise continuous boundaries which may have some points of *** are used to obtain a simplified formula for estimating the first passage ***,the results are also generalized to the case of two-sided general nonlinear *** can be easily carried out with Monte Carlo method and it is demonstrated for several typical two-sided boundaries that the proposed approximation method offers a highly accurate approximation of first passage density.

关键词： Boundary non-crossing probability first density passage density two-sided piecewise continuous boundaries Brownian motion