实际气体R134a在离心叶轮内部流动的数值研究

使用实际气体模型对R134a在半开式离心压缩机叶轮内部三维湍流进行了数值计算,比较了比容比相等情况下实际及理想气体模型对压缩过程的差异.研究表明二者设计流量系数基本相等,但实际气体的多变效率低于相应的理想气体计算值;数值计算能够较好地预测实际气体的流动结构和性能参数的变化规律,对实际气体制冷压缩机气动热力设计具有理论及工程意义.     

B splines有限基矢集用于多体微扰计算

讨论了用B splines构造有限正交基矢集的方法,并将这种基矢用于超精细相互作用的多体微扰计算,得到了与实验一致的结果。 关键词：     

广义Fibonacci数的一些恒等式

利用非数学归纳法,以及广义Fibonacci数的性质,得到了广义Fibonacci数的一些求和公式.     

卟啉取代侧链在LB膜结构中的取向研究

本文研究了５，１０，１５，２０－四（对－山嵛酸乙酯－α－氧代苯基）卟啉在气－液界面的成膜性能。在优化实验条件下制备了该化合物的多层ＬＢ膜。利用偏振ＦＴ－ＩＲ谱测定了卟啉上脂链取代基在ＬＢ膜结构中的取向。结果表明脂链轴线与载片法线间夹角为２７°。     

A NEW MODEL FOR ESTIMATION OF DIFFUSION COEFFICIENT OF PHENOL DESORPTION WITHIN POLYMERIC RESIN UNDER ULTRASOUND

4 new model, phase equilibrium-kinetics model (PEKM), for estimation of diffusioncoefficient was proposed in this paper. Kinetic experiments of phenol desorption on NKAII resin inthe presence and the absence of ultrasound were separately conducted, and diffusion coefficients ofphenol within an adsorbent particle were estimated by means of proposed PEKM and classicsimplified model. Results show that the use of ultrasound not only changes the phase equilibriumstate of NKAll resin/phenol/water system which had been equilibrium at normal condition, but alsoenhances diffusion of phenol within the resin. The diffusion coefficient of phenol in the resin in thefield of ultrasound increases in an order of magnitude in comparison with the diffusion coefficientdetermined under no ultrasound Experimental results also indicated that the diffusion coefficientsestimated by PEKM were more accurate than that estimated by the classic simplified model.     

Gas chromatographic/mass spectrometric measurement of deuterium-labelled valine,leucine, isoleucine and phenylalanine in the human body

N-Trifluoroacetyl-n-butyl ester derivatives of deuterium-labelled valine, leucine, isoleucine and phenylulanine were analysed by the isotope dilution technique and gas chromatography/mass spectrometry (GC/MS). Selected ion retrieval and peak-area integration were applied. The conditions adopted gave good separations with a short experimental time and high intensity. Ratios of the total isotopic abundance and metabolic kinetic curves were obtained. The regression coefficient of the standard dilution curve was 0.99 and the relative standard deviation was 0.3%. The stabilities of the amino acid derivatives were also tested.     

A SIRS epidemic model with infection-age dependence

Based on J. Mena-Lorca and H.W. Hethcote's epidemic model, a SIRS epidemic model with infection-age-dependent infectivity and general nonlinear contact rate is formulated. Under general conditions, the unique existence of its global positive solutions is obtained. Moreover, under more general assumptions than the existing, the existence and asymptotical stability of its equilibria are discussed. In the end, the condition on the stability of endemic equilibrium is verified by a special model.     

BP神经网络电子束扫描均匀度校正系统

 电子束的扫描均匀度是工业辐照电子直线加速器的重要技术指标，该校正系统利用人工神经网络中的误差反向传播法可以对扫描电流波形进行校正，以克服扫描磁场引起的电子束形状变化、位置改变等造成的电子束分布的不均匀性，从而使扫描曲线的归一化均方偏差达到1.8%。     

自相似曲线与Whitney型临界集

本文讨论一类（包括Ｋｏｃｈ曲线在内的）自相似曲线，证明了其上的简单曲线是Ｗｈｉｔｎｅｙ型临界集，并在微小扰动下仍是简单曲线．     

75°前缘后掠角细长三角翼失速特性实验研究

本文简介了前缘后掠角为７５°的平板三角翼在西北工业大学ＮＦ－３低速风洞中的测力和相关的激光片光流动显示实验，给出了部分实验结果，并与文献［１－３］的结果进行了比较，虽然各种来源的结果存在着明显的差异，但ＮＦ－３风洞两种测试手段的实验结果却具有良好的相关性。