一类新型绝对接近关联度分析模型及应用

定义了一种新的灰色接近关联度模型—绝对接近关联度。研究了现有接近关联度的性质及问题,进而提出了新型绝对接近关联度的定义;研究了绝对接近关联度的计算方法;探讨了绝对接近关联度所具有的若干性质;将绝对接近关联度模型用于基于三角模糊数的多属性决策中,算例说明了方法的应用步骤和可行性。     

An Anomalous Gain Mechanism in GaN Schottky Barrier Ultraviolet Photodetectors

The gain mechanism in GaN Schottky barrier ultraviolet photodetectors is investigated by focused light beam. When the incident light illuminates the central region of the Schottky contact electrode, the responsiyity changes very little with the increase of reverse bias voltage. However, when the incident light illuminates the edge region of the electrode, the responsivity increases remarkably with the increase of reverse bias voltage, and the corresponding quantum efficiency could be even higher than 100%. It is proposed that the surface states near the edge of the electrode may lead to a reduction of effective Schottky barrier height and an enhancement of electron injection, resulting in the anomalous gain.     

基于云模型和灰关联的学生-校企双导师三边不确定匹配方法研究

三边匹配是一种典型的多边匹配模式.在三边匹配中,决策者的满意度是影响匹配结果的关键.考虑到个人的预期偏好,选用预期偏好与实际评价值的距离作为满意度.为充分反映自然语言的模糊性和随机性,设计了基于云模型的灰色关联度测算方法,以反映云模型的距离和形状的相似性.此外,随着信息技术的快速发展,不同个体之间的独立状态被打破,决策...     

Analysis of localization effect in blue-violet light emitting InGaN/GaN multiple quantum wells with different well widths

Four blue-violet light emitting InGaN/GaN multiple quantum well(MQW) structures with different well widths are grown by metal–organic chemical vapor deposition. The carrier localization effect in these samples is investigated mainly by temperature-dependent photoluminescence measurements. It is found that the localization effect is enhanced as the well width increases from 1.8 nm to 3.6 nm in our experiments. The temperature induced PL peak blueshift and linewidth variation increase with increasing well width, implying that a greater amplitude of potential fluctuation as well as more localization states exist in wider wells. In addition, it is noted that the broadening of the PL spectra always occurs mainly on the low-energy side of the PL spectra due to the temperature-induced band-gap shrinkage, while in the case of the widest well, a large extension of the spectral curve also occurs in the high energy sides due to the existence of more shallow localized centers.     

热电器件综合性能表征系统及实验研究

基于直流瞬态Harman法测量热电器件优值系数原理,搭建热电器件综合性能表征实验系统,实现同时测量热电器件无量纲优值系数（ZT值）、Seebeck系数、电导率以及热导率,并通过Labview编程完成对实验系统的控制、数据采集、实时显示和处理。制作并改进具有夹层结构的热电器件,对此开展了性能测试评估。实验结果表明,室温下夹层结构热电器件ZT值小于常规Bi₂Te₃器件,但Seebeck系数比常规器件大;夹层结构器件电导率和热导率均大于常规器件值。     

Thickness measurement of GaN epilayer using high resolution X-ray diffraction technique

In this paper we propose a new method for measuring the thickness of the GaN epilayer, by using the ratio of the integrated intensity of the GaN epilayer X-ray diffraction peaks to that of the sapphire substrate ones. This ratio shows a linear dependence on the GaN epilayer thickness up to 2 μm. The new method is more accurate and convenient than those of using the relationship between the integrated intensity of GaN epilayer diffraction peaks and the GaN thickness. Besides, it can eliminate the absorption effect of the GaN epilayer.     

Evaluation of both composition and strain distributions in InGaN epitaxial film using x-ray diffraction techniques

The composition and stain distributions in the InGaN epitaxial films are jointly measured by employing various x-ray diffraction (XRD) techniques, including out-of-plane XRD at special planes, in-plane grazing incidence XRD, and reciprocal space mapping (RSM). It is confirmed that the measurement of (204) reflection allows a rapid access to estimate the composition without considering the influence of biaxial strain. The two-dimensional RSM checks composition and degree of strain relaxation jointly, revealing an inhomogeneous strain distribution profile along the growth direction. As the film thickness increases from 100 nm to 450 nm, the strain status of InGaN films gradually transfers from almost fully strained to fully relaxed state and then more In atoms incorporate into the film, while the near-interface region of InGaN films remains pseudomorphic to GaN.     

稀土硝酸盐与三缩四乙二醇-二-(8-喹啉基)醚固体配合物的合成

合成了三缩四乙二醇-二-(8-喹啉基)醚(Ⅰ)配体,并首次合成了与十四个稀土硝酸盐的固体配合物.用IR、TG、DTA等测试确定固体配合物组成为[Ln(NO_3)_3]_3(Ⅰ)_2(Ln=La、Ce、Pr、Nd)和CLn(NO_3)_3)_3(Ⅰ)·H_2O(Ln=Sm-Yb和Y).配体(Ⅰ)和配合物[La(NO_3)_3)]_3(Ⅰ)_2核磁共振谱分析表明,醚链上的质子向低场位移,喹啉环上质子向高场位移,这说明镧与配体(Ⅰ)中喹啉上的氮是直接配位的.     

基于Vague集多准则决策的新的评分函数

评分函数是Vague集多准则决策过程中影响决策结果的一个重要因素.针对模糊环境下多准则决策问题,首先,指出现有文献所构造的评分函数的缺陷.其次,在整合前人工作的基础上,为同时兼顾真、假隶属度的绝对差距和未知度对决策结果的贡献,提出了一种新的评分函数,有效地解决了决策结果与直觉判断不符的问题,并在多方案的评分函数值相等时,给出了合理的决策规则,为决策者做出科学决策提供了一种方便有效的方法.最后,通过实例阐明新评分函数的有效性和优越性.     

基于贝叶斯算法的CPU散热片结构自动优化

本文基于数值模拟、结构设计、优化设计以及贝叶斯优化算法提出一种针对散热片结构的自动优化框架,并对CPU正弦式散热片的振幅、周期和高度进行结构优化。结果表明,优化后的正弦式散热片与平板式散热片和初始正弦式散热片相比,表面平均努塞尔数提高了195%,表面最高温度降低了6.51?C。分析了优化前后正弦散热片场协同角的变化,进一步证实了流场和温度场协同性能对散热的本质影响。