Preparation and characterization of rare earth doping YAG phosphors and Y-TZP nanopowder

本文用丙烯酰胺体系高分子网络凝胶法进行了低温制备稀土掺杂YAG（钇铝石榴石，Y3Al5O12）纳米荧光粉（含YAG:Eu3+、YAG:Ce3+和YAG:Tb3+三个系统）的研究和探索，研究了热处理温度和掺杂浓度对发光性能的影响；探索了用MOCVD（金属有机化学气相沉积）制备YAG:Eu3+荧光粉的新方法；用高分子网络凝胶法成功制备了Y-TZP（Y2O3稳定的四方相ZrO2）纳米粉。主要成果和进展如下： 1)聚丙烯酰胺体系高分子网络凝胶法能显著降低YAG的合成温度，XRD和TG-DTA分析表明，在850℃时，系统仅存在纯YAG相。XRD分析和SEM观察显示，粉体颗粒粒径纳米级，分布范围较窄；随...In the present paper, a novel way named polyacrylamide gel method was employed to synthesize the rare earth doping YAG (yttrium aluminum garnet, Y3Al5O12) nano-sized YAG: Eu3+, YAG: Ce3+ and YAG: Tb3+ phosphors at low temperature, respectively. Effects of the heating temperature and the doping concentration of the YAG nano-sized phosphor were evaluated. MOCVD (metal organic chemical vapor depositi...学位：理学硕士院系专业：化学化工学院化学系_有机化学学号：20042504

Impact of Remote Phosphor Shape on LED Luminous Performance

研究了不同驱动电流和光强分布条件下,圆顶形、椭球形以及圆锥形远程荧光粉的发光性能。实验采用蓝光LED激发YAG：Ce3＋荧光粉产生白光,并通过恒流源和TEC控温热沉分别控制LED驱动电流和热沉温度,通过对三种不同形状远程封装的荧光粉的光、色指数等进行对比,发现椭球状样品的综合光学特性最佳,光通量最高。同时,三种远程荧光粉分别进行了不同电流下的Yellow-blue Ratio（YBR）空间分布测试,结果显示,圆顶形样品的YBR空间分布均匀性最好,且在不同电流下ACCTD及ACU值在三种样品中最优。相比大角度,三种样品在0°附近测量的YBR的值都有不同程度的下降,原因是芯片法线方向的荧光粉离光源较远,且光通过荧光粉的光程较短,因此激发效果与大角度出光时有差别。光源的封装形状以及荧光粉形状都成为影响光分布的重要因素,因此通过改变远程荧光粉的封装方式,优化出射光线路径,可以起到改善远程荧光粉发光性能的重要作用,对完善大功率白光LED光学特性的研究具有较好的参考价值。The luminous performances of remote phosphor with domed, elliptical and conical shapes under various drive currents and light intensity distributions are researched. A blue LED is used as the light source to excite YAG：Ce3＋ phosphor to emit white light. Meanwhile, constant-current sources and TEC heat sink controllers are used to control LED driving current and heat sink temperature respectively. Comparing the optical and chromatic parameters of three remote packing phosphor samples with different shapes, it is found that the elliptical sample has the best optical characteristics and the highest luminous flux. Yellow-blue ratio （YBR） spatial distribu- tion tests of the three kinds of remote phosphor are performed respectively under different currents. The domed sample shows the best YBR spatial distribution uniformity, ACCTD and ACU value are the best among three samples. Comparing to big angle, the YBR values of the three samples measured closed to 0° decrease at different lev-els for the phosphor layer at the normal direction of the chip far away from the light source and shorter optical path in phosphor, so the excitation effect is different from that of the big angle exit light. Based on experimental phenomenon, shapes of light source encapsulation and phosphor layer become important factors to influence light distribution. Therefore, the exit light path is optimized through changing the packing way of the remote phosphor, which is important to improve remote phosphor illumination performances and has better reference to the research on high power white light LED optical performances.科技部国际合作项目（2015DFG62190）;科技部港澳台科技合作专项资助项目（2015DFT10120）; 国家自然科学基金（61504112,11604285,51605404）; 福建省自然科学基金（2016R0091）; 福建省经信委企业技术创新项目专

Novel Edge-preserving Algorithm for Defocus Blurred Image Restoration

图像复原过程中图像的主观视觉质量与图像的局部细节信息之间密切相关。针对散焦模糊图像,提出一种新的图像复原方法。所提方法在传统双边总变分正则化方法基础上,通过引入一种具有结构自适应的局部权值函数,构造了一种新的图像复原目标函数。该目标函数综合考虑了图像的全局与局部统计特性,即在整体保真情况下还充分考虑了图像的局部结构信息,使得所提复原方法能更有效地保持图像的边缘等细节信息。与传统bTV正则化方法的比较实验表明,所提方法在边缘保持方面更有效,复原后的图像具有更好的主、客观视觉质量。Relevant research on image restoration indicates that image's subjective visual quality is closely related to its local details.A novel restoration algorithm for defocus blurred image was proposed.The proposed algorithm based on BTV regularization framework by introducing a local adaptive weighted function constructs a new cost function for ima-ge restoration.This cost function which not only takes into account the global data-fidelity,but also considers the local statistical properties of image,meaning to fully consider the local structural features of image under global data-fidelity,hence behaves much better in edge preservation.Experimental results confirm the effectiveness of the proposed method.The image is restored with better subjective and objective visual quality,compared with other methods such as traditio-nal BTV regularization approach.福建省自然科学基金(2008J0032;2009J01301;2009J01302);厦门大学985二期信息创新平台资助项目(0000-X07204);厦门市科技计划高校创新项目(3502Z20083006)资

制度变革、非正式制度与会计审计行为——中国会计学会英文期刊China Journal of Accounting Studies(CJAS)2018年第二次学术研讨会会议综述

2018年10月26日,由中国会计学会、中国会计学会对外交流专业委员会主办,厦门大学会计学系承办的中国会计学会对外学术交流专业委员会学术年会暨China Journal of Accounting Studies 2018年第二次学术研讨会在厦门大学隆重举行。来自复旦大学、中山大学、中国人民大学、西安交通大学、厦门大学、重庆大学、湖南大学、暨南大学、香港中文大学、香港城市大学、美国纽约州立大学石溪分校、澳大利亚新南威尔士大学、对外经贸大学、中央财经大学等三十多所境内外高等院校和研究机构的90余名专家学者参加了本次学术研讨会,围绕会议主题\"制国家自然科学基金重大项目课题“制度变革、非正式制度因素与会计审计行为研究”(71790602);;教育部人文社科基地重大项目“文化影响、会计信息质量与审计行为”(16JJD790032)资

日・中・シンガポールの職業会計人育成制度の比較研究

This paper aims to compare the status of the development of the education program of the accounting profession in Japan, China and Singapore. And this study is to compare the educational program for the qualification of Certified Public Accountants.International Education Standards (IES) has been published by worldwide organization of accounting profession IFAC, and every countries should follow the rule of IES, especially when education programs are set in non-European countries. When the international education standards (IES) published by the International Federation of Accountants (IFAC) is considered to be standard, the current state education programs in three countries are examined.Among three countries, Singapore’s education program contain almost the same content and quality of IES. On the other hand, education programs of Japan and China have differences in the following three points; (1) required skills are not show clearly, (2) required program to participate and (3) the period of work experience is short one year (3 years vs 2 years)

有效消除光晕现象和颜色保持的彩色图像增强算法

由于对图像中明暗突变区域的背景光照估计不准确,经典Retinex彩色图像增强算法易产生光晕现象且存在增强后图像细节信息减弱和颜色失真等不足.为此,结合人眼视觉特性提出一种彩色图像增强算法.首先利用人眼对图像结构特征及颜色信息的敏感特性,通过构造彩色双边滤波器来获取图像背景光照,以避免光照突变处产生光晕现象;其次依据人眼系统局部自适应调节特性,通过引入一个对比度调节函数自适应增强图像的细节信息,克服经典Retinex算法在整体对比度提高的同时局部对比度下降的不足;最后利用一种线性的颜色恢复算法恢复增强所得亮度图像的颜色信息.与MSRCR等彩色图像增强算法比较的实验结果表明,文中算法更有效,增强后的图像不仅细节清晰,而且色彩鲜艳、自然

基于自适应超完备稀疏表示的图像去噪方法

基于超完备字典的图像稀疏表示是一种新的图像表示理论,利用超完备字典的冗余性可以有效地捕捉图像的各种结构特征,从而实现图像的有效表示。当前稀疏表示的理论研究主要集中在稀疏分解算法和字典构造算法两方面。本文提出一种新的超完备字典构造算法:K-LMS算法,该算法由K均值聚类算法泛化获得,可用于超完备字典的自适应更新,以实现图像的有效表示。针对图像去噪问题,本文给出一种基于超完备稀疏表示的去噪方法,该方法利用图像在超完备字典上的自适应稀疏分解,通过阈值处理的方法实现了图像去噪,实验结果证实了本文所提方法的有效性

有效保持细节特征的图像椒盐噪声滤除方法

论文结合几种去噪方法,提出一种统一的图像去噪模型.该模型通过一个统一的目标函数将图像去噪问题转化为最优化问题,目标函数的构造主要包括估计残差惩罚函数、局部权函数及正则化项三个方面.随后基于此模型提出一种新的去除椒盐噪声的非线性滤波方法,其中估计残差惩罚函数采用L1范数形式,局部权函数采用自适应高斯核函数,正则化项则利用图像的小波域稀疏性作为先验约束来构造.由于充分融合了图像的全局和局部统计特性,因而在抑制噪声的同时能够更好地保持图像边缘等细节特征,相关去噪实验结果证实了本文方法的有效性

一种新的基于彩色双边滤波的彩色图像增强方法

本文提出一种新的基于彩色双边滤波的彩色图像增强方法。该方法将彩色图像增强分为三部分:全局亮度调节、对比度增强和颜色恢复。全局亮度调节主要是对图像的整体亮度信息进行非线性调整,压缩图像的亮度动态范围;局部对比度增强主要是利用彩色双边滤波获得像素点所在邻域的背景亮度,由当前像素点的亮度与背景亮度之间的关系,通过非线性的方法增强图像局部对比度;最后通过颜色恢复算法恢复图像色彩。相关实验表明,本文所提方法可以获得很好的彩色图像增强效果

Synthesis of ultrafine spherical YAG : Eu3+ phosphors by MOCVD

KeyWords Plus: YAG-TB PHOSPHOR; LUMINESCENT PROPERTIES; COMBUSTION PROCESS; SPRAY-PYROLYSIS; CE PHOSPHOR; PHOTOLUMINESCENCE; PARTICLES; MORPHOLOGY; POWDERS 通讯作者地址: Zeng, RJ (通讯作者), Xiamen Univ, Coll Mat Sci, Sinning S Rd 22, Xiamen 361005, Peoples R China 地址: 1. Xiamen Univ, Coll Mat Sci, Xiamen 361005, Peoples R China 电子邮件地址: [email protected] Europium-doped yttrium aluminum garnet (YAG:Eu3+) phosphor powders, with uniform diameters of about 1 mu m, have been prepared by metallorganic chemical vapor deposition (MOCVD). The metal-organic precursors have been characterized by thermogravimetry-differential scanning calorimeter (TG-DSC). The phosphor powders have been identified by X-ray diffraction (XRD), scanning electron microscope (SEM) and photoluminescence measurements. It shows that the YAG:EU3+ particles annealed at 1473 K for 3 h are nonaggregated and spherical, the diameter of particles is in the range of 1-2 mu m. Phase-pure YAG which is of spherical shaped particles have been obtained and observed good luminescence property. Three major emission peaks were observed at 589, 594, and 607 nm