轴流压气机转子叶片的流固耦合分析

本文针对压气机转子叶片流固耦合问题,采用耦合平台MpCCI连接商业CFD软件FINE/Turbo与CSM软件ABAQUS模拟了设计转速下不同流量工况点的流固耦合问题,对比了流场定常计算与流固耦合非定常计算的结果,得到了叶片振动位移频谱振幅图以及效率和压比变化曲线。研究结果表明在失速点附近叶片振动对流场有显著影响,由此可以对压气机的颤振问题进行预测。     

计算流体成像技术重构方法及其应用

建立系统的计算流体成像(CFI)技术,并论证其为流动数值模拟与风洞实验相互佐证的重要手段。采用纯数值模拟技术重构得到流场计算阴影、纹影以及干涉图,主要技术包括复杂湍流模拟技术、三线性插值技术和流动图像重构技术等。同时将CFI技术应用于激波管内绕障碍物三维复杂流动计算图像重构,并与双向全息实验结果进行了比较分析。研究证明该CFI技术可以用于复杂几何边界、分区域、非定常流动图像重构,不仅能够为流场结构特征分析提供重要参考依据,而且能够用于数值模拟与风洞实验结果的比较印证。     

基于人眼视觉的集成成像三维显示分辨率的比较

为了对不同集成成像系统三维显示应用中的视觉分辨效果进行表征, 提出了一种基于人眼视觉的集成成像三维显示分辨率的分析比较方法. 通过分析集成成像三维显示系统的分辨率与人眼在最佳显示观看距离下分辨本领的关系, 定义了相对分辨率参数, 分析了其与集成成像三维显示实际观看时视觉分辨效果的关系. 研究结果表明, 透镜阵列的大小对集成成像三维显示的视觉分辨效果有重要的影响. 针对两个系统实例的理论计算结果表明, 系统间的相对分辨率参数差异是传统分辨率差异的1.75倍, 实验结果与理论分析一致. 该研究方法对三维显示分辨率的评价有一定的指导意义.     

Photoluminescence from screen printed ZnO based nanocrystalline films

Photoluminescence from ZnO based films deposited by screen printing is studied. PL spectra of undoped films show strong broad green emission around 500 nm and a weak (nearly one fourth of visible) UV emission around 398 nm. Further enhancement of 30% in the green emission is observed as 5 at.% Ca is doped in ZnO which for higher dopant concentration falls monotonously. The films are polycrystalline and the particle size lies between 33 to 47 nm as determined by Debye‐Scherrer method. Film with 5 at.% doping is under tensile strain and the others are under compressive strain. SEM shows microclusters, consisting of nanoparticles, scattered throughout the substrate which club together with increase in dopant amount. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

多变量三维风场的简化及应用

三维空间风场在三个方向上相关性很小,可认为各个方向是相互独立的。对于输电线路的影响而言顺风向脉动作用是主要的,远大于其它两个方向,可简化为一维风场计算。以小波为分析工具,实现由风载荷功率谱到风速一时间历程的转变,并对模拟结果进行了比较。研究结果表明：小波分析在风载荷模拟中可靠性较高,可为输电线路风响应的进一步研究提供参考。     

航空结构铝合金Ⅰ/Ⅱ复合型断裂的三维弹塑性数值分析

在LC4CS铝合金三维Ⅰ/Ⅱ复合型断裂实验的基础上,对Ⅰ/Ⅱ复合型加载模型进行了细致的三维弹塑性有限元计算,系统分析了不同复合度φ和厚度B对裂纹端部应力场和起裂角的影响.结果表明,对于不同φ和B的试样,周向应力极大值和三维离面约束因子极小值出现在相同的角度;根据最大周向应力准则,在Ⅰ型载荷占主导(βeq＞65.45°)...     

Effect of film thickness controlled by ink‐jet printing method on the optical properties of an electroluminescent polymer

Ink‐jet printing (IJP) represents a highly promising liquid processed polymer deposition method for the film preparation of functional polymers in photo‐electronic devices. In this report, the results on the IJP of a fluorene‐based electroluminescent polymer, poly(9,9‐dihexylfluorene‐alt‐2,5‐dioctyloxybenzene) (PF6OC8), from a piezoelectric droplet generator are presented. The polymer film thickness has been found to show an approximate linear relation with the number of droplets per unit area; it is thus convenient to control the film thickness by the space of printed dots in IJP process. In comparison, spin coating approach is also used to prepare polymer films with different thicknesses by varying solution concentration and spinning speed. However, it is found that spin coating is difficult to control the film thickness quantitatively. The influence of film thickness on the photoluminescence (PL) properties of PF6OC8 films prepared by IJP and spin coating is comparatively investigated. For both ink‐jet printed and spin coated films, the intensity of PL spectra first increases and then decreases with increase in the film thickness, probably due to the exciton quenching in thicker films. When the polymer film thickness is at nanoscale, the major peak in the PL spectrum is the 0–0 vibronic emission at about 420 nm, and with increase in the film thickness, the 0–1 vibronic peak at about 440 nm becomes dominant. The red‐shifted PL spectra with increase in film thickness show the change from the 2D exciton state to the 3D one. Copyright © 2009 John Wiley & Sons, Ltd.     

三维荧光二阶校正法快速测定块茎类蔬菜、土壤和污水中克百威残留量

克百威是一种高效内吸广谱氨基甲酸酯类杀虫剂.本文充分利用荧光光谱仪操作简单、灵敏度高,化学计量学二阶校正算法具有的"二阶优势",将三维荧光(EEM)与化学计量学交替三线性分解(ATLD)算法相结合,实现了红薯、土豆、红萝卜、土壤和污水5种实际复杂体系中克百威残留量的直接快速定量测定.当选取组分数为2时,用ATLD获得的平均回收率分别为(99.0±5.3)%、(97.2±4.2)%、(102.7±5.9)%、(101.1±3.8)%和(91.3±1.9)%.另外,还用椭圆置信区间(EJCR)测试和品质因子,如灵敏度(SEN)、选择性(SEL)、检测下限(LOD)和预测均方根误差(RSMEP)评估了该种算法的准确性.实验结果表明,该方法能以"数学分离"代替繁琐的"化学分离",成功地解决实际复杂体系中内源干扰物质与分析物光谱重叠所引起的难分辨的问题,可用于未知干扰共存下克百威含量的直接快速定量测定.     

Micro-contact printing of poly(3-hexylthiophene) on silicon oxide: Effect of stamp stretching

Micro-contact printing (μCP) has been applied to deposit poly(3-hexylthiophene) (P3HT) layer onto silicon oxide substrate from a polydimethylsiloxane (PDMS) stamp. The effect of the stamp stretching onto the corresponding printed P3HT layer has been analysed both from morphological (AFM) and from structural (XRD) points of view. Results show an orienting effect of the stretching towards the P3HT ultimate morphological units (i.e. fibrils) along the stretching direction. The influence of other variables involved in the deposition (substrate polarity/apolarity, mechanical pressure onto the stamp) have been studied and reported.     

Thermal Performance Enhancement of Thermosyphon Heat Pipe with Binary Working Fluids

Thermal performance of a thermosyphon heat pipe using ethanol-water and TEG-water with variations of parameters such as the mixture content, the pipe diameter, and the working temperature have been studied in this research work. From the experiments, it is found that at low temperature of heat source (less than 80^oC), the ethanol-water mixture has a higher heat transfer rate than that of water and close to that of pure ethanol. In the case of TEG-water mixture, the heat transfer rate of the thermosyphon varies with the content of TEG in the mixture, and it is found that TEG in the mixture can increase the critical heat flux due to the flooding limit in a small thermosyphon. The boiling equation of Rohsenow and the condensation equation of Nusselt are modified to predict the heat transfer coefficients inside the thermosyphon. For the mixtures, the weighted average of the heat transfer coefficient of each component can be used to predict the total heat transfer coefficient. Furthermore, it is found that Faghri's equation can be used to predict the critical heat flux due to the flooding limit of the thermosyphon with the binary mixtures.