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Nariaki Sugiura 《Journal of multivariate analysis》1976,6(4):500-525
Asymptotic expansions of the joint distributions of the latent roots of the Wishart matrix and multivariate F matrix are obtained for large degrees of freedom when the population latent roots have arbitrary multiplicity. Asymptotic expansions of the distributions of the latent vectors of the above matrices are also derived when the corresponding population root is simple. The effect of normalizations of the vector is examined. 相似文献
144.
采用密度泛函理论和MonteCarlo模拟方法研究了2-氨基-2-咪唑啉在气相和水中的异构现象和质子迁移反应.考虑了直接迁移和水助催化迁移等两种质子迁移途径.气相中稳定点的几何结构和热力学性质是在B3LYP/6-311+G**理论水平上计算得到的.溶剂效应的研究结果表明,水作为溶剂可降低直接迁移途径的速率,有利于水助催化反应途径的进行. 相似文献
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《Journal of Coordination Chemistry》2012,65(2):129-138
Abstract The ESR spectra of a series of copper(II) alkanoates with the empirical formula Cu2 X 4 (X = heptanoate, octanoate, nonanoate, decanoate, dodecanoate), and their pyridine adducts have been measured over the temperature range 300K to 100K. The spectra of nonadduct copper(II) alkanoates exhibit extreme temperature dependent behavior; the room temperature spectra show a single broad line centered on g ≈ 2.1, however as the temperature is lowered triplet state features appear. The corresponding pyridine adducts give typical triplet state spectra at all temperatures. This temperature behavior can be interpreted in terms of interdimer interactions in copper(II) alkanoates having the polymeric structure. The observed resonance lines are used to calculate the zero-field splitting parameters D and E. The spin Hamiltonian and zero-field splitting parameters are used to estimate the exchange parameter J. The values of /2J/ for the compounds investigated are in the range of 300–400cm?1 and suggest that the copper(II) ions are strongly antiferromagnetically coupled. 相似文献
147.
This paper describes a novel measuring system for investigating the influence of pressure and temperature on the mechanical
properties of time-dependent polymer materials. The system can measure the volume and the shear relaxation moduli of solid
polymer specimens simultaneously subjected to temperatures from −50 to +120°C with a precision of ±0.01°C, and pressures from
atmospheric to 500 MPa with a precision of ±0.1 MPa. The paper demonstrates the measuring capabilities of the apparatus. For
poly(vinyl) acetate (PVAc) are presented sample measurements of the shear relaxation modulus as function of time, pressure
and temperature; specific volume; the bulk creep compliance; the coefficient of thermal expansion; the bulk modulus; and the
pressure drop experiments which simulate conditions to which a material is exposed during the injection molding process. The
shear moduli may be measured in the range from 1 to 4,000 MPa with the relative error of 3%.The error of volumetric measurements
is 0.05%, which corresponds to 0.00005 cm3/g. In all cases results are shown as measured, no additional smoothing or filtering was employed.
This paper is dedicated to Professor Nicholas W. Tschoegl on the occasion of his 87th birthday, for his contributions to the
field of time-dependent bulk properties of polymeric materials. 相似文献
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以滑动体静力平衡的两个力平衡方程为基础,引入拉氏乘子,将土压力问题以变分学观点来描述,转化为确定含有两个函数自变量的泛函极值问题。依据泛函取极值时必须满足的欧拉方程,得出了主动土压力和被动土压力在取极值时,墙后土体的破坏是沿平面滑动。然后,将土压力的泛函极值问题进一步转化为带有约束的函数极值问题。这种函数极值可利用M atlab6.1优化工具箱提供的fm incon函数进行求解。当土体的粘聚力等于0时,土压力计算结果与库仑土压力理论解完全一致;而当土体的粘聚力不等于0时,归纳给出了相应的土压力计算公式。 相似文献
150.