GdAlO3∶Tb3+-Al2O3有序共晶生长及其微结构研究

两相有序共晶材料由于具有不同折射率的两晶相呈现有序排列,可降低荧光在共晶材料内部的散射而实现导光功能,可被应用于高分辨探测成像器件中。本工作根据定向凝固原理,用微下降法生长技术制备得到了直径为3 mm的GdAlO₃∶Tb³⁺-Al₂O₃两相有序共晶。通过SEM和元素分析,探究了GdAlO₃∶Tb³⁺-Al₂O₃共晶内部的微结构,结果显示,所得共晶中GdAlO₃∶Tb³⁺晶相均匀有序地分布于基质Al₂O₃晶相中,GdAlO₃∶Tb³⁺晶相直径的大小受生长速率的影响,速率越快,直径越小。所制备得到的GdAlO₃∶Tb³⁺-Al₂O₃有序共晶在X射线辐照下发射出明亮的绿色荧光,并在GdAlO₃∶Tb³⁺晶相中定向传播,有望被用作X射线探测成像材料,提高探测器的空间分辨率。     

Ce3+∶GdLu2Al5O12/Al2O3共晶微结构及其发光性能

稀土共晶闪烁体是通过定向凝固晶体生长技术,将具有不同折射率的两相制备成具有射线探测功能的共晶材料,其中含有激活离子的闪烁体相的折射率高于基质相。在高能射线辐照下,闪烁体相将入射高能射线转换成荧光,然后,荧光在闪烁体相和基底相的界面以全反射的形式实现定向输出,从而有效提高辐射探测成像的空间分辨率。本工作采用微下降法成功生长得到φ3 mm×117.0 mm 的1.0%(原子数分数)Ce∶GdLu₂Al₅O₁₂/Al₂O₃闪烁共晶样品。通过切割抛光加工得到φ3 mm×2.0 mm的共晶薄片,并将该共晶薄片进行微观结构、能谱分析和荧光性能等表征和测试,结果表明所得到的共晶样品由Ce∶GdLuAG和Al₂O₃两晶相构成,微观结构呈现出“中国结”结构,并在生长方向呈现出一定的有序排列。荧光光谱测试表明该共晶材料存在Gd³⁺-Ce³⁺间的能量传递,具有典型的Ce³⁺辐射跃迁,其中双宽峰发射峰最强位于560 nm。此外,根据生长速率对共晶样品发射峰强、峰位以及荧光寿命影响,优化出最佳下拉生长速率为4.0 mm/min。     

A class of multiobjective linear programming models with random rough coefficients

In the present paper, we concentrate on dealing with a class of multiobjective programming problems with random rough coefficients. We first discuss how to turn a constrained model with random rough variables into crisp equivalent models. Then an interactive algorithm which is similar to the interactive fuzzy satisfying method is introduced to obtain the decision maker’s satisfying solution. In addition, the technique of random rough simulation is applied to deal with general random rough objective functions and random rough constraints which are usually hard to convert into their crisp equivalents. Furthermore, combined with the techniques of random rough simulation, a genetic algorithm using the compromise approach is designed for solving a random rough multiobjective programming problem. Finally, illustrative examples are given in order to show the application of the proposed models and algorithms.     

掺三价铈离子四偏磷酸盐NaLn(PO3)4 (Ln=La, Gd)的真空紫外光谱研究

用高温固相法合成了NaLn（PO3）4：1．0％（原子分数）Ce^3＋（Ln=La,Gd）两种粉末发光材料,在合肥国家同步辐射实验室（NSRL）测得两种样品中Ce^3＋的真空紫外光谱。根据真空紫外光谱图,得到了两种稀土偏磷酸盐中所掺Ce^3＋离子5d轨道的能级分裂图。结合NaLa（PO3）4和NaGd（PO3）4的单晶结构数据,发现随着Ln-O平均键长的减小,Ce^3＋离子5d轨道的晶场劈裂（εcfs）、重心位移（εc）和总的红移（total redshilt,D）均增大。根据配体极化模型,计算了两种化合物中掺杂Ce^3＋离子的有效平均键长（Reff）和光谱极化率（αsp）,发现随着平均键长Rav（Ln—O）变短,Ce^3＋离子的光谱极化率（αsp）也随之减小。     

成都市信息技术产业的计量经济模型

本文针对成都市信息技术产业的实际情况,依据市电子工业局提供的数据建立了成都市信息技术产业的计量经济模型．该模型由８ 个方程组成,包含８ 个内生变量和１２ 个外生变量．根据模型的方程体系,对成都市现有的电子信息产业结构进行分析,揭示了市电子工业总产出的影响因素,提出了该行业结构优化的建议方案,并给出了一个可行的预测方程;分部类排序结果表明成都市信息技术产业化仍停留在分立元器件基础阶段,产业发展水平亟待提高     

一个基于Sidrauski宏观经济动力学模型的分析

Abstract. This paper formulates a kind of dynamical macro-economic model based onSidrauski‘s work,then presents the sufficient and necessary conditions of the stability of modelat equilibrium states ,and shows some results for special production functions.     

A Class of Chance Constrained Multi-objective Portfolio Selection Model Under Fuzzy Random Environment

This paper deals with a class of chance constrained portfolio selection problems in the fuzzy random decision making system. An integrated fuzzy random portfolio selection model with a chance constraint is proposed on the basis of the mean-variance model and the safety-first model. According to different definitions of chance, we consider two types of fuzzy random portfolio selection models: one is for the optimistic investors and the other is for the pessimistic investors. In order to deal with the fuzzy random models, we develop a few theorems on the variances of fuzzy random returns and the equivalent partitions of two types of chance constraints. We then transform the fuzzy random portfolio selection models into their equivalent crisp models. We further employ the ε-constraint method to obtain the efficient frontier. Finally, we apply the proposed models and approaches to the Chinese stock market as an illustration.