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961.
We present results from a novel variational method for the study of beam propagation in a Kerr medium with nonlinear absorption. This new method combines the variational method and a nonlinear absorption equation and gives a concise expression for the combination. The results obtained with this method show good quantitative agreement with numerical solutions obtained with the finite-difference method. It is shown that the variational method takes much less time than a numerical simulation with the finite-difference method for analysis of beam propagation in a thick medium with nonlinear absorption and nonlinear refraction. The new method makes detailed analysis of beam propagation in a Kerr medium with nonlinear absorption very simple and fast. 相似文献
962.
963.
Electroluminescence peaking at 1.3 μm is observed from high concentration boron-diffused silicon p+-n junctions. This emission is efficient at low temperature with a quantum efficiency 40 times higher than that of the band-to-band emission around 1.1μm, but disappears at room temperature. The 1.3-μm band possibly originates from the dislocation networks lying near the junction region, which are introduced by high concentration boron diffusion. 相似文献
964.
965.
966.
We construct a broad class of generalized Bayes minimax estimators of the mean of a multivariate normal distribution with covariance equal to σ2Ip, with σ2 unknown, and under the invariant loss δ(X)−θ2/σ2. Examples that illustrate the theory are given. Most notably it is shown that a hierarchical version of the multivariate Student-t prior yields a Bayes minimax estimate. 相似文献
967.
Si wafers are widely used as a substrate material for fabricating ICs. The quality of ICs depends on the quality of Si wafers. The chemo-mechanical grinding (CMG) with soft abrasive grinding wheels (SAGW) has been recently found to be a great potential process for machining Si wafers to generate superior surface quality at low cost. However, there have been very few studies on observing variation of topography of scratch/texture and understanding basic eliminating process of scratch/texture on the ground Si wafer. Furthermore, few reports on the variation of surface roughness and material removal rate (MRR) during CMG process and relationship between MRR and surface roughness during CMG process are presented. In this paper, a series of CMG experiments have been conducted to study the elimination process of artificial scratches created on etched Si surfaces and residual textures induced by SD1500 diamond wheel in CMG process, and to understand the topography variations of Si surfaces and some basic grinding characteristics during CMG process. 相似文献
968.
In this paper, we are concerned with the existence of positive solutions for a singular p-Laplacian differential equation
(φp(u'))'+β/r φp(u')-γ |u'|^p/u + g(r)=0,0〈r〈1,
subject to the Dirichlet boundary conditions: u(0) = u(1) =0, where φp(s) = |sl^P-2s,p 〉 2,β 〉0, γ〉(p-1)/p (β + 1), and g(r) ∈ C^1 [0, 1] with g(r) 〉 0 for all τ ∈ [0, 1]. We use the method of elliptic regularization, by carrying out two limit processes, to get a positive solution. 相似文献
(φp(u'))'+β/r φp(u')-γ |u'|^p/u + g(r)=0,0〈r〈1,
subject to the Dirichlet boundary conditions: u(0) = u(1) =0, where φp(s) = |sl^P-2s,p 〉 2,β 〉0, γ〉(p-1)/p (β + 1), and g(r) ∈ C^1 [0, 1] with g(r) 〉 0 for all τ ∈ [0, 1]. We use the method of elliptic regularization, by carrying out two limit processes, to get a positive solution. 相似文献
969.
We have performed a detailed investigation on the world investment networks constructed from the Coordinated Portfolio Investment Survey (CPIS) data of the International Monetary Fund, ranging from 2001 to 2006. The distributions of degrees and node strengths are scale-free. The weight distributions can be well modeled by the Weibull distribution. The maximum flow spanning trees of the world investment networks possess two universal allometric scaling relations, independent of time and the investment type. The topological scaling exponent is 1.17±0.02 and the flow scaling exponent is 1.03±0.01. 相似文献
970.
Chen Zhou 《Extremes》2008,11(3):281-302
In this paper, we build a two-step estimator , which satisfies , where is the well-known maximum likelihood estimator of the extreme value index. Since the two-step estimator can be calculated easily as a function of the observations, it is much simpler to use in practice. By properly choosing the
first step estimator, such as the Pickands estimator, we can even get a shift and scale invariant estimator with the above property.
The author thanks Laurens de Haan for motivating this work and giving helpful comments. The author also thanks two anonymous
referees for their useful comments. 相似文献