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211.
This paper provides simulation comparisons among the performance of 11 possible prediction intervals for the geometric.mean of a Pareto distribution with parameters (αB, ). Six different procedures were used to obtain these intervals , namely; true inter -val , pivotal interval , maximum likelihood estimation interval, centrallimit teorem interval, variance stabilizing interval and a mixture of the above intervals . Some of these intervals are valid if the observed sample size m,are large , others are valid if both, n and the future sample size m, are large. Some of these intervals require a knowledge of α or B, while others do not. The simulation validation and efficiency study shows that intervals depending on the MLE's are the best. The second best intervalsare those obtained through pivotal methods or variance stabilization transformation. The third group of intervals is that which depends on the central limit theorem when λ is known. There are two intervals which proved to be unacceptable under any criterion. 相似文献
212.
213.
J. Thuburn 《国际流体数值方法杂志》2011,66(1):123-133
Different discretizations of the gradient and curl operators are considered for a staggered grid in a height‐based terrain‐following coordinate system. A combination of discrete operators is identified that guarantees the mimetic property that the curl of the gradient of any scalar vanishes identically. The result is illustrated with some numerical examples. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
214.
Tzu-Sheng Shane Hsu Timothy Fitzgerald Vincent Phuc Nguyen Trisha Patel Balakumar Balachandran 《Acta Mechanica Sinica》2017,33(2):327-340
Studies of fluid-structure interactions associated with flexible structures such as flapping wings require the capture and quantification of large motions of bodies that may be opaque. As a case study, motion capture of a free flying Manduca sexta, also known as hawkmoth, is con-sidered by using three synchronized high-speed cameras. A solid finite element (FE) representation is used as a reference body and successive snapshots in time of the displacement fields are reconstructed via an optimization procedure. One of the original aspects of this work is the formulation of an objective function and the use of shadow matching and strain-energy regularization. With this objective function, the authors penalize the projection differences between silhou-ettes of the captured images and the FE representation of the deformed body. The process and procedures undertaken to go from high-speed videography to motion estimation are dis-cussed, and snapshots of representative results are presented. Finally, the captured free-flight motion is also characterized and quantified. 相似文献
215.
WU Jin-Jie HENG Yue-Kun SUN Zhi-Jia WU Chong ZHAO Yu-Da YANG Gui-An JIANG Chun-Hua 《中国物理C(英文版)》2008,32(3)
A new charge measurement method, time over threshold (TOT), has been used in some gas detectors lately. Here TOT is studied for TOF system, made of plastic scintillator counter, which can simplify the electronics of the system. The signal characteristics are measured and analyzed with a high quality oscilloscope, including noise, pedestal, signal amplitude, total charge, rise time and the correlation between them. The TOT and charge are related and can be fitted by some empirical formula. The charge measurement resolution by TOT is given and this will help the design of TOF electronics. 相似文献
216.
217.
We prove a uniform bound for the density, p
t
(x), of the solution at time t(0, 1] of a 1-dimensional stochastic differential equation, under hypoellipticity conditions. A similar bound is obtained for an expression involving the distributional derivative (with respect to x) of p
t
(x). These results are applied to extend the Itô formula to the composition of a function (satisfying slight regularity conditions) with a hypoelliptic diffusion process in the spirit of the work of Föllmer et al.
(5) 相似文献
218.
根据问题的特点 ,选择 Logistic判别模型 ,并借鉴普通线性回归的逐步向前法 ,用似然比统计量 ( Deviance)来筛选自变量 (因素 ) .结果显示 :在 1 1个因素中 ,有 3个是作用显著的 ,而其中舒张压值极为重要 .为降低再出血率 ,将其控制在 85 mm Hg以下是有效而可行的 相似文献
219.
In the paper calculation of the moments of inertia for nuclei from the region 87 ≤ Z ≤ 100 and 130 ≤ N ≤ 156 was made in dependence on the angular momentum of their rotational states. The experimental values of the moments of
inertia were calculated for rotational energy of the classic rotor in its quantum form, with the use of a simple formula.
The moment of inertia term appearing in the formula was treated as a variable. The calculations were carried out on the basis
of experimental data for the energies of the rotational levels for 51 bands built on ground states for even-even nuclei and
for nuclei with odd mass number A. In addition, 30 rotational bands built on excited states were also analysed in the investigated region in case of even-even
nuclei. For many bands and nuclei the considered dependence of the moment of inertia on angular momentum has been found in
the analytical form by fitting polynomials to the experimental data. It turned out that obtained results for the moments of
inertia made it possible to describe the energies of rotational levels with a relative deviation not greater or only slightly
greater than 1%. In general, in the case of 12 bands of ground level the maximum relative deviation of obtained level energies
is smaller than 1%.
相似文献
220.
一阶时滞微分方程解的零点分布 总被引:3,自引:0,他引:3
Abstract. The paper gives two estimates of the distance between adjacent zeros of solutions 相似文献