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Global Existence and Energy Decay for a Coupled System of Kirchhoff Type Equations with Damping and Source Terms

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Acta Mathematicae Applicatae Sinica 2016年第3期32卷 731-738页

作者： Yao-jun ye Department of Mathematics and Information Science Zhejiang University of Science and Technology Hangzhou 310023 China

This paper deals with the global existence and energy decay of solutions to some coupled system of Kirchhoff type equations with nonlinear dissipative and source terms in a bounded domain. We obtain the global existence by defining the stable set in H0^1 （Ω） × H1 （Ω）, and the energy decay of global solutions is given by applying a lemma of V. Komornik.

关键词： a coupled system of Kirchhoff-type equation initial boundary value problem global solutions energy decay

融合相似预报方法在陇东南短期强降水预报中的应用

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高原气象 2025年第1期44卷 214-223页

作者：黄晓远李旭杜梦莹叶培龙李艳兰州大学大气科学学院甘肃兰州730000 兰州中心气象台甘肃兰州730020

基于逐步过滤相似法和自组织映射(SOM)神经网络方法,提出了一种融合相似预报方法。利用ECMWF模式预报产品、ERA5再分析资料和地面气象台站观测数据,使用该方法对2021-2022年陇东南地区开展了时效为72 h的强降水预报试验,并对预报效果进... 详细信息

基于逐步过滤相似法和自组织映射(SOM)神经网络方法,提出了一种融合相似预报方法。利用ECMWF模式预报产品、ERA5再分析资料和地面气象台站观测数据,使用该方法对2021-2022年陇东南地区开展了时效为72 h的强降水预报试验,并对预报效果进行了检验。结果表明:(1)融合相似预报方法的TS评分处于4.5%~9.1%之间,与ECMWF模式预报结果相比表现出一定的优势。随着预报时效的增长,强降水预报的TS评分呈现减小的趋势,其在08:00(北京时,下同)起报的TS评分相对较高。(2)相比于单独使用逐步过滤相似预报,融合相似预报方法的准确性有所提升,并能在一定程度上降低空报率。其中08:00起报和20:00起报的TS评分提高了1.31%和0.63%,而FAR同时下降了2.39%和1.25%。

关键词：强降水短期预报相似预报逐步过滤相似自组织映射(SOM)

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Existence and asymptotic behavior for systems of nonlinear hyperbolic equations

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Applied Mathematics(A Journal of Chinese Universities) 2015年第4期30卷 453-465页

作者： ye Yao-jun Department of Mathematics and Information Science Zhejiang University of Science and Technology

The initial-boundary value problem for a class of nonlinear hyperbolic equations system in bounded domain is studied. The existence of global solutions for this problem is proved by constructing a stable set, and obta... 详细信息

关键词： Nonlinear hyperbolic equations system global solutions asymptotic behavior difference inequal-ity damping and source terms.

Microstructural Feature and Evolution of Rapidly Solidified Ni3Al-Based Superalloys

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Acta Metallurgica Sinica(English Letters) 2019年第6期32卷 764-770页

作者： ye-Fan li Chong li Jing Wu Hui-jun li Yong-Chang liu Hai-Peng Wang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science and EngineeringTianjin UniversityTianjin 300354China Department of Applied Physics School of ScienceNorthwestern Polytechnical UniversityXi'an 710129China

The Ni3Al-based superalloy was rapidly solidified in the form of droplets with varying *** cooling rate(Rc)is a function of diameter(D)of *** the decrease in droplet sizes(increase in the cooling rates),the volume fraction ofγ’+γeutectic structure increases from 21.31(D=1400 lm,Rc=3.6 9 102 K s-1)to 36.31%(D=270 lm,Rc-=2.3 9 103 K s-1).Moreover,unimodal size distribution of nano-γ’exists in the droplets instead of bimodal dual-size distributions ofγprecipitates that are normal in as-cast alloys.

关键词： Ni3Al-based superalloy Microstructure Rapid solidification γ’precipitate

A parametric bootstrap approach for one-way classification model with skew-normal random effects

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Applied Mathematics(A Journal of Chinese Universities) 2019年第4期34卷 423-435页

作者： ye Ren-dao XU li-jun LUO Kun JIANG ling School of Economics Hangzhou Dianzi UniversityHangzhou 310018China Alibaba Business College Hangzhou Normal UniversityHangzhou 310016China

In this paper,several properties of one-way classification model with skew-normal random effects are obtained,such as moment generating function,density function and noncentral skew chi-square distribution,*** on the EM algorithm,we discuss the maximum likelihood(ML)estimation of unknown *** testing problem of fixed effect,a parametric bootstrap(PB)approach is ***,some simulation results on the Type I error rates and powers of the PB approach are obtained,which show that the PB approach provides satisfactory performances on the Type I error rates and powers,even for small *** illustration,our main results are applied to a real data problem.

关键词： parametric bootstrap EM algorithm one-way classification model skew-normal distribution skew chi-square distribution

Corrosion and tribocorrosion resistance of MAO-based composite coating on AZ31 magnesium alloy

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Journal of Magnesium and Alloys 2022年第12期10卷 3406-3417页

作者： Siqin liu Guihua li Yuming Qi Zhenjun Peng Yinping ye jun liang State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000PR China Key Laboratory of Science and Technology on Wear and Protection of Materials Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000PR China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049PR China

In this paper, a multi-functional composite coating with low friction coefficient, high wear resistance and excellent tribocorrosion resistance is fabricated on AZ31 Mg alloys by micro-arc oxidation and spray-coating methods. The microstructure, and composition of the coating are characterized by SEM, EDS, XRD, and FT-IR. Potentiodynamic polarization and EIS tests are conducted to evaluate the corrosion resistance of the composite coating. The tribocorrosion property is also studied using pin-on-disk tribometer in 3.5 wt.% Na Cl solution. It is found that the composite coating possesses better long-term corrosion resistance than the single MAO coating. The tribocorrosion tests prove that the composite coating exhibits much better wear and tribocorrosion resistance than the single MAO coating and can protect the substrate from corrosion under a sliding condition.

关键词： Magnesium alloy Micro-arc oxidation Composite coating Corrosion Tribocorrosion

Experimental Investigation on Performance of Pulse Detonation Rocket Engine Model

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Chinese Journal of Aeronautics 2007年第1期20卷 9-14页

作者： li Qiang FAN Wei YAN Chuan-jun HU Cheng-qi ye Bin School of Engine and Energy Northwestern Polytechnical University Xi＇an 710072 China

The PDRE test model used in these experiments utilized kerosene as the fuel, oxygen as oxidizer, and nitrogen as purge gas. The solenoid valves were employed to control intermittent supplies of kerosene, oxygen and purge gas. PDRE test model was 50 mm in inner diameter by 1.2 m long. The DDT （deflagration to detonation transition） enhancement device Shchelkin spiral was used in the test model. The effects of detonation frequency on its time-averaged thrust and specific impulse were experimentally investigated. The obtained results showes that the time-averaged thrust of PDRE test model was approximately proportional to the detonation frequency. For the detonation frequency 20 Hz, the time-averaged thrust was around 107 N, and the specific impulse was around 125 s. The nozzle experiments were conducted using PDRE test model with three traditional nozzles. The experimental results obtained demonstrated that all of those nozzles could augment the thrust and specific impulse. Among those three nozzles, the convergent nozzle had the largest increased augmentation, which was approximately 18%, under the specific condition of the experiment.

关键词： pulse detonation rocket engine impulse nozzle experimental investigation

Strong near-infrared and ultrafast femtosecond nonlinearities of a covalently-linked triply-fused porphyrin dimer-SWCNT nanohybrid

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Nano Research 2022年第2期15卷 1355-1365页

作者： Lulu Fu jun ye Hui li Zhipeng Huang Mark GHumphrey Chi Zhang China-Australia Joint Research Center for Functional Molecular Materials School of Chemical and Material EngineeringJiangnan UniversityWuxi 214122China China-Australia Joint Research Center for Functional Molecular Materials School of Chemical Science and Engineerinz Ton^ii UniversityShanghai 200092China Research School of Chemistry Australian National UniversityCanberraACT 2601Australia

Functional materials displaying large ultrafast third-order optical nonlinearities across a wide spectral region and broad temporal domain are required for all-optical signal *** desirable is nonlinear optical(NLO)activity at near-infrared(NIR)wavelengths with femtosecond *** the first triply-fused porphyrin dimer(TFP)-functionalized single-walled carbon nanotube(SWCNT)nanohybrid was successfully constructed by covalently grafting TFPs onto *** results of Z-scan techniques demonstrate that the newly obtained TFP-SWCNT nanohybrid was found with a strong NLO performance under both nanosecond and femtosecond *** the nanosecond regime,an enhancement in optical limiting(OL)of the TFP-SWCNT nanohybrid is seen at 532 nm when compared with the performance of porphyrin monomer-functionalized SWCNT nanohybrid *** femtosecond irradiation,the TFP-SWCNT nanohybrid exhibits a particularly strong OL effect with a giant two-photon absorption(TPA)cross section value(ca.15,500 GM)at 800 nm pulses that mainly stems from intense TPA of TFP,in sharp contrast to the Por-SWCNT nanohybrid which exhibits only saturable absorption under identical *** results demonstrate that the newly-developed TFP-SWCNT nanohybrid is a very promising OL candidate for practical applications across wide spectral and temporal domains,and that covalently functionalizing carbon-based materials with triply-fused chromophores may be a useful approach to engineering adaptable photonic devices with broad-ranging NLO activity.

关键词： triply-fused porphyrin dimer carbon nanotube near-infrared femtosecond nonlinear optical materials

Learning a hierarchical image manifold for Web image classification

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Journal of Zhejiang University-Science C(Computers and Electronics) 2012年第10期13卷 719-735页

作者： Rong ZHU Min YAO li-hua ye jun-ying XUAN School of Information Engineering Jiaxing UniversityJiaxing 314001China School of Computer Science and Technology Zhejiang UniversityHangzhou 310027China

Image classification is an essential task in content-based image ***,due to the semantic gap between low-level visual features and high-level semantic concepts,and the diversification of Web images,the performance of traditional classification approaches is far from users' *** an attempt to reduce the semantic gap and satisfy the urgent requirements for dimensionality reduction,high-quality retrieval results,and batch-based processing,we propose a hierarchical image manifold with novel distance measures for *** that the images in an image set describe the same or similar object but have various scenes,we formulate two kinds of manifolds,object manifold and scene manifold,at different levels of semantic *** manifold is developed for object-level classification using an algorithm named extended locally linear embedding(ELLE) based on intra-and inter-object difference *** manifold is built for scene-level classification using an algorithm named locally linear submanifold extraction(LLSE) by combining linear perturbation and region *** results show that our method is effective in improving the performance of classifying Web images.

关键词： Web image classification Manifold learning Image manifold Semantic granularity Distance measure