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91.
92.
Using a corrected sum rule and a generalized virial identity, we study the analytical expression for entire modes of the collective elementary excitation spectrum in a trapped Bose–Einstein condensate at any atom number. Explicit analytical formulas for the spectrum are obtained for the harmonic traps with both spherical symmetry and axial symmetry using the gaussian approximation for the N-body ground-state wave function of the condensate. These formulas give the simple dependence of all energy levels on the atom numbers, their interaction strength and trap geometry parameters. 相似文献
93.
A comprehensive study of hazelnut oil composition with comparisons to other vegetable oils,particularly olive oil. 总被引:4,自引:0,他引:4
Benitez-Sánchez Pedro Luis León-Camacho Manuel Aparicio Ramón 《European Food Research and Technology》2003,218(1):13-19
Crude and refined hazelnut oils from different countries were characterised by major and minor compounds. Fatty acids, triacylglycerides, waxes, sterols, methyl-sterols, terpenic and aliphatic alcohols, tocopherols, tocotrienols and hydrocarbons were identified and quantified by gas chromatography and high-performance liquid chromatography. The levels of these chemical compounds in hazelnut oils together with the equivalent carbon numbers and triacylglyceride carbon numbers, were compared with the results of analyses of samples of other vegetable oils. The statistical procedure of cluster analysis was used to characterise hazelnut oils versus other edible oils. 相似文献
94.
基于模式理论光栅椭偏参数反演的数值模拟 总被引:5,自引:2,他引:3
将一种广泛用于求解系统优化问题的方法——正单纯形法,求解光栅的椭偏方程。首先,利用求解光栅的傅立叶模式理论对TE和TM波的复反射系数进行求解。然后计算出其相应的椭偏参数(△,Ψ),并在该值的基础上加入不同偏差的随机高斯噪声,将加入噪声后的值(△m,Ψm)作为模拟测量值。最后使用优化算法进行反演。通过对几种常用面形光栅椭偏参数的数值模拟,一方面表明傅立叶模式理论计算光栅的椭偏参数不仅精度高。而且速度快;另一方面表明利用正单纯形法得到的光栅参数值很接近于正演时假设的参数值,从而从理论上证明了利用椭偏法测量光栅各种光学参数的可行性。 相似文献
95.
X. Gong W. Ma J.C. Ostrowski K. Bechgaard G.C. Bazan A.J. Heeger S. Xiao D. Moses 《Advanced functional materials》2004,14(4):393-397
The electronic properties, carrier injection, and transport into poly(9,9‐dioctylfluorene) (PFO), PFO end‐capped with hole‐transporting moieties (HTM), PFO–HTM, and PFO end‐capped with electron‐transporting moieties (ETM), PFO–ETM, were investigated. The data demonstrate that charge injection and transport can be tuned by end‐capping with HTM and ETM, without significantly altering the electronic properties of the conjugated backbone. End‐capping with ETM resulted in more closely balanced charge injection and transport. Single‐layer electrophosphorescent light‐emitting diodes (LEDs), fabricated from PFO, PFO–HTM and PFO–ETM as hosts and tris[2,5‐bis‐2′‐(9′,9′‐dihexylfluorene)pyridine‐κ2NC3′]iridium(III ), Ir(HFP)3 as the guest, emitted red light with brightnesses of 2040 cd m–2, 1940 cd m–2 and 2490 cd m–2 at 290 mA cm–2 (16 V) and with luminance efficiencies of 1.4 cd A–1, 1.4 cd A–1 and 1.8 cd A–1 at 4.5 mA cm–2 for PFO, PFO–HTM, and PFO–ETM, respectively. 相似文献
96.
H-bond and conformations of donors and acceptors in model polyether based polyurethanes 总被引:1,自引:0,他引:1
The molecular mechanics (MM) method with COMPASS force field was used to study the H-bonds in the polyether based polyurethane model molecules. Availability of the calculation was firstly verified in comparison of some H-bonded model molecules, which were studied by using ab initio calculation, and those calculated by MM. Based on a urethane model molecule 1,3-dimethylcarbamate, which can be donor or acceptor and behaves in various conformations, it is reasonable to have a large number of H-bond interactions between various conformational donors and acceptors. For examining all the possible interaction patterns, we studied 57H-bond complexes. This systematic modeling covers well-known four types of interaction patterns, such as NH?OC (Type I), NH?O-CO (Type II), NH?NH (Type III), NH?COC (Type IV) in the system. Obtained H-bond energies were used to analyze the probabilities of the complexes. For the interaction within the hard segments, or Type I, Type II and Type III, a predominant H-bond complex has been found in the present study, which belongs to Type I. For the interaction between the hard segment and the soft segment, two conformations of Type IV were calculated to be existed. 相似文献
97.
A note on the Gauss-Jacobi quadrature formulae for singular integral equations of the second kind 总被引:1,自引:0,他引:1
A fast and efficient numerical method based on the Gauss-Jacobi quadrature is described that is suitable for solving Fredholm
singular integral equations of the second kind that are frequently encountered in fracture and contact mechanics. Here we
concentrate on the case when the unknown function is singular at both ends of the interval. Quadrature formulae involve fixed
nodal points and provide exact results for polynomials of degree 2n − 1, where n is the number of nodes. Finally, an application of the method to a plane problem involving complete contact is presented. 相似文献
98.
优化项目管理MIS系统方案设计 总被引:2,自引:0,他引:2
按照工程项目“五制”管理的要求 ,以规范管理和提升工程质量为系统开发的基础和前提 ,探索适合本行业使用的项目MIS系统设计方案 ,并对其功能模型、数据规划、构造处理模型、数学模型进行分析 相似文献
99.
一个新颖的轮廓线跟踪算法 总被引:1,自引:0,他引:1
提出了一个新颖的基于隐马尔科夫模型与光流的轮廓线跟踪算法。曲线描绘由B样条形状空间向量来表达,能够捕捉全局和局部变形。提出应用沿曲线的光流计算来预测曲线在下一帧的位置,在预测曲线的基础上,提出应用隐马尔科夫模型来准确定位曲线的位置。隐马尔科夫模型提供了一种有效的概率手段来融合多种量测特征比如边缘,曲线平滑性,区域灰度或颜色统计信息等等,能够更准确的定位曲线位置。基于仿射形状空间的实验了表明本文所提出算法的有效性。 相似文献
100.