PPS适应性整群抽样下估计量的研究

在群规模存在差异时,最有效的抽样方法是PPS整群抽样;在单元存在聚集性且总体信息不明确时,使用PPS适应性整群抽样是最有效的.利用PPS适应性整群抽样设计中的样本外推机制产生的样本信息,对HH和HT估计进行调整,提出修正的HH和HT估计,并对估计量的性质进行了研究.     

基于计算机视觉技术的茶叶品质随机森林感官评价方法研究

为弥补茶叶品质感官审评存在的缺陷，利用计算机视觉技术对茶叶品质进行快速无损评价研究。以碧螺春绿茶为对象，依据专家感官审评结果，将茶样分成4个等级；采用中值滤波及拉普拉斯算子对茶样图像进行预处理，并提取预处理后的茶样图像的颜色特征和纹理特征以表征茶叶图像的外形特征，利用随机森林算法对茶叶外形特征属性进行重要性排序；筛选出重要性较大的特征及随机森林算法中最优的决策树棵数建立感官评价模型，并与建立的支持向量机(SVM)模型性能相比较。结果表明：色调均值、色调标准差、绿体均值、平均灰度级、饱和度均值、红体均值、饱和度标准差、亮度均值、一致性等9个特征属性的重要性较大，且与感官审评特征描述结果相一致；当采用优选出的9个重要性较大的特征及决策数棵数为500时，建立的模型性能最优，模型总体判别率为95.75%，Kappa系数为0.933，OOB误差为5%，较SVM模型分别提高了3.5%，0.066，优选的9个重要性较大的图像特征与感官审评特征描述相一致。研究表明：利用随机森林方法筛选出对茶叶外形特征属性贡献最大的少数几个特征建立模型，模型性能就能达到很好的识别效果，模型得到简化，同时模型精度和稳定性都高于其他方法。     

中国区域间技术创新的空间溢出效应研究

本文结合新经济地理学K关联的思想构造了外部技术创新溢出指数模型,在此基础上运用2006~2014年中国30个省级行政区的面板数据对中国区域间技术创新空间溢出效应进行了实证研究,结果表明:(1)全国技术创新溢出效应主要是东部地区带动的,东部地区的省份对东部、中部和西部地区其他省份存在技术创新溢出效应,而中部和西部并没有对其他地区技术创新产生溢出效应,并且中部地区和西部地区内部各省之间存在竞争效应。(2)无论是全国还是东部、中部和西部地区,R&D经费、R&D人员和知识存量均对技术创新产生正向作用,并且这些地区的技术创新产出均处于规模报酬递减阶段,不同的是,全国、东部和中部地区R&D人员对技术创新的贡献比R&D资本要大,而西部地区R&D资本对技术创新的贡献则要大于R&D人员。     

Quantum Anti-Zeno Effect in Artificial Quantum Systems

In this paper, we study a quantum anti-Zeno effect （QAZE） purely induced by repetitive measurements for an artificial atom interacting with a structured bath. This bath can be artificially realized with coupled resonators in one dimension and possesses photonic band structure like Bloeh electron in a periodic potential. In the presence of repetitive measurements, the pure QAZE is discovered as the observable decay is not negligible even for the atomic energy level spacing outside of the energy band of the artificial bath. If there were no measurements, the decay would not happen outside of the band. In this sense, the enhanced decay is completely induced by measurements through the relaxation channels provided by the bath. Besides, we also discuss the controversial golden rule decay rates originated from the van Hove＇s singularities and the effects of the counter-rotating terms.     

Directed Transport of Brownian Particles in a Periodic Channel

The transport of Brownian particles in the infinite channel within an external force along the axis of the channel has been studied. In this paper, we study the transport of Brownian particle in the infinite channel within an external force along the axis of the channel and an external force in the transversal direction. In this more sophisticated situation, some property is similar to the simple situation, but some interesting property also appears.     

Simultaneous jumps in two two-level atoms

We demonstrate the importance of collective behaviour in two identical two-level atoms. When the atoms become very close together a cascade three-level atom analysis can be adopted to show the increasing possibility of simultaneous jumps. Due to the dipole-dipole interaction the intermediate one-atom excited state is detuned by a large amount when the atoms are close together but leaving the upper two-atom excited state in two-photon resonance. The relative importance of multiple jumps compared with stepwise independent jumps is then changed dramatically.     

The Infrared Spectra of the First Transition Series Metal(II) Bis(Aquo) Complexes Of 8-Hydroxyquinoline

Abstract

The infrared spectra (700–100 cm^?1) of the complexes [M(ox)₂(H₂O)₂] (ox = 8-hydroxyquinolinate anion, M = Mn, Fe, Co, Ni, Cu, Zn) are discussed. For the purposes of assignment of the metal ligand modes, deuterated 8-hydroxyquinoline-d ₇ was prepared by the Skraup synthesis and the spectra of the deuterated complexes were compared with those of the unlabelled species. Furthermore, [⁶⁴Zn(ox)₂(H₂O)₂] and [⁶⁸Zn(ox)₂(H₂O)₂] were prepared by reaction of ⁶⁴ZnSO₄ and ⁶⁸ZnSO₄ with 8-hydroxyquinoline and the effects of metal isotope labelling on the spectra were examined and compared with earlier isotopic data on the nickel and zinc complexes.     

Experimental evidence for supercontinuum generation by fission of higher-order solitons in photonic fibers

We report on an experimental study of supercontinuum generation in photonic crystal fibers with low-intensity femtosecond pulses, which provides evidence for a novel spectral broadening mechanism. The observed results agree with our theoretical calculations carried out without making the slowly varying envelope approximation. Peculiarities of the measured spectra and their theoretical explanation demonstrate that the reason for the white-light generation in photonic crystal fibers is fission of higher-order solitons into redshifted fundamental solitons and blueshifted nonsolitonic radiation.     

二项指数和四次混合均值的计算

本文研究了二项指数和四次均值的计算问题.利用初等数论及代数数论的方法获得了一个精确的计算公式以及一个转换公式,推广了已有的结果,揭示了均值计算与同余方程组的本质联系.