水、甲醇和乙醇溶剂在PVA膜材料中无限稀释扩散系数测定

用气相色谱法研究小分子溶剂与聚合物材料之间的相互作用是一种快速、准确和方便的方法,该方法可以测量多种小分子溶剂在聚合物中的溶解和扩散行为.采用该方法测定了水、甲醇、乙醇在固定液PVA中的保留时间和半峰宽,运用van Deemter模型进行数据处理,得到了上述几种小分子在PVA膜材料中的无限稀释扩散系数,获得了有意义的结果.     

周期弹性支承管的稳定性研究

运用传递矩阵方法得到了周期弹性支承载流管的传播常数,利用传播常数确定失稳的临界状态,进而对稳定性进行了研究。结果表明：周期弹性支承管结构的静力型失稳与杆的轴压失稳情况相似,等效的轴向压力由无量纲化的流体流速和流体压力确定。弹性支座的线刚度和转角刚度之间须满足一定的匹配关系才能使结构得到相应较高的临界的等效压力。     

Cu-4wt%Ti合金有序化X射线与电子衍射谱的计算机模拟

在点阵波理论基础上,通过假定Cu-4wt%Ti合金中溶质原子浓度的适当分布并建立与之相应的衍射波波幅表达式,利用计算机模拟得该合金调幅分解与有序化共存时X射线衍射边带形貌,其波形与实验结果颇为相近;进一步根据波的叠加原理在两相互垂直方向上对上述衍射形貌合成,获得Cu-4wt%Ti合金400℃时效较长时间同时出现的D1a型和B2型复杂有序化超点阵斑,其强度与位置分布均与透射电镜(TEM)衍射谱完全一致. 关键词：     

A compact graphene Q-switched erbium-doped fiber laser using optical circulator and tunable fiber Bragg grating

We demonstrate a passively Q-switched tunable erbium-doped fiber laser(EDFL)based on graphene as a saturable absorber(SA).A three-port optical circulator(OC)and a strain-induced tunable fiber Bragg grating(TFBG)are used as the two end mirrors in an all-fiber linear cavity.The Q-switched EDFL has a low pump threshold of 23.8 mW.The pulse repetition rate of the fiber laser can be widely changed from 9.3 kHz to 69.7 kHz by increasing the pump power from23.8 mW to 219.9 mW.The minimum pulse duration is 1.7μs and the highest pulse energy is 25.4 nJ.The emission wavelength of the laser can be tuned from 1560.43 nm to 1566.27 nm by changing the central wavelength of the straininduced TFBG.     

Performance improvement of AlGaN-based deep ultraviolet light-emitting diodes with double electron blocking layers

The AlGaN-based deep ultraviolet light-emitting diodes(LED) with double electron blocking layers(d-EBLs) on both sides of the active region are investigated theoretically. They possess many excellent performances compared with the conventional structure with only a single electron blocking layer, such as a higher recombination rate, improved light output power and internal quantum efficiency(IQE). The reasons can be concluded as follows. On the one hand, the weakened electrostatic field within the quantum wells(QWs) enhances the electron–hole spatial overlap in QWs, and therefore increases the probability of radioactive recombination. On the other hand, the added n-AlGaN layer can not only prevent holes from overflowing into the n-side region but also act as another electron source, providing more electrons.     

基于复杂性和成本的NPD项目权变管理策略研究

本文在项目管理的选择法和学习法的组合模式的基础上,提出同时采用多方案并行和强化学习两种管理策略能有效应对NPD项目的复杂性。在如何决定并行数量和学习强度的问题上,基于效率准则进行了理论分析,提出了主要的权变变量,即复杂性和成本。并基于NK模型进行了仿真模拟,探讨了不同情境下,项目绩效随两种管理策略的变化规律。     

变系数两点边值问题的有限元强校正格式

该文利用投影型插值,对于变系数两点边值问题,获得了一个高精度的有限元强校正格式,数值实验更验证了这一结果．     

THE ANALYSIS OF THE TRANSLATION-TORSION COUPLING EARTHQUAKE RESPONSES OF SINGLE-STORY ECCENTRIC FACTORY BUILDINGS WITH CONSIDERATION OF ROOF WHOLE-SPACE-WORK

In this paper, the translation-torsion coupling earthquake responses, of single-story ecoentric factory buildings with consideration of whole-space-work of the roof in 3-dimension non-inertia system are analysed and studied, and its calculation model has been established. And what is more, corresponding motion equations of earthquake responses have been derived, analysed and discussed. And it points out that under the action of the earthquake including rotational component, the principle of superposition of independent action for each earthquake component and mode-superposition method of dynamic responses analysis are already not applicable. In this paper, the translation-torsion coupling earthquake responses of sorne singlestory eccentric factory building are calculated and analysed by comparison methods without consideration of the earthquake torsional component. The conclusion is that when whole-space-work of the roof is considered, the results of calculation are more conformable to the actual earthq     

非晶态TbFe2薄膜的磁性和电性

本文研究了TbFe₂非晶态薄膜的磁性和电性,测量了M_s(T)(77—800K),ρ(T)(4.2—400K)和穆斯堡尔谱(18K,400K),得到居里温度T_c～400K,电阻极小值温度T_min～360K,在T<360K范围内观察到温度系数为负的类Kondo效应,用Hesse和Window两种不同方法解出了室温穆斯堡尔谱的超精细场,得到了H=210kOe和H=25kOe两种分布,其中前一组给出了铁磁性,后一组可能与类Ko 关键词：     

矫顽力新理论与低温下的特大内禀磁硬度

二卷长度一样的声像带,录放节目相差几倍;二台功率相同的发电机,体积和重量相差几十倍;二块大小相当的磁铁,吸引的物体相差几百倍.原因是什么?它们的矫顽力不同是重要原因之一.矫顽力不但是标志磁性材料品质、进行分类的主要依据[譬如矫顽力大于 10 kA/m(126 Oe)的为永磁材料,小于 1kA/m(12.6Oe)的为软磁材料,介于两者之间的称为半永磁材料],而且是为材料创新和改善指引方向的物理量(如分析矫顽力受什么因素控制,从而在制备材料时,有意识地控制这些因素,以达到人们的要求). 矫顽力定义为静态饱和磁滞回线上磁通密度(磁感应强度)B为零时的…