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排序方式: 共有8999条查询结果,搜索用时 15 毫秒
961.
962.
963.
964.
研究了光子加速器(即利用等离子体中的朗谬尔波实现光脉冲频率上转换)所涉及的基本物理问题.文中导出了在存在朗谬尔波的条件下,光脉冲频率对于等离子体本底密度及电子密度扰动的依赖关系,并就最大频率转换、光脉冲俘获、波的加速位相(accelerating phase)以及位相滑动(phase slippage)效应进行讨论. 相似文献
965.
We study the problem of parameter estimation for time-series possessing two, widely separated, characteristic time scales.
The aim is to understand situations where it is desirable to fit a homogenized single-scale model to such multiscale data.
We demonstrate, numerically and analytically, that if the data is sampled too finely then the parameter fit will fail, in
that the correct parameters in the homogenized model are not identified. We also show, numerically and analytically, that
if the data is subsampled at an appropriate rate then it is possible to estimate the coefficients of the homogenized model
correctly.
The ideas are studied in the context of thermally activated motion in a two-scale potential. However the ideas may be expected
to transfer to other situations where it is desirable to fit an averaged or homogenized equation to multiscale data. 相似文献
966.
967.
This paper considers estimating parameters in the discrete distributions of order k such as the binomial, the geometric, the Poisson and the logarithmic series distributions of order k. It is discussed how to calculate maximum likelihood estimates of parameters of the distributions based on independent observations. Further, asymptotic properties of estimators by the method of moments are investigated. In some cases, it is found that the values of asymptotic efficiency of the moment estimators are surprisingly close to one. 相似文献
968.
Tsu-Chiang Yen Jer-Wei Chang Jenn-Ming Lin Rong-Jyh Chen 《Optics Communications》1998,150(1-6):158-162
This work examines the feasibility of using incoherent optical feedback to generate high-frequency optical signals in a semiconductor laser. At a roundtrip feedback distance of 30 cm, a signal appears at around 1 GHz while the laser output is kept in single longitudinal mode and single polarization. The proposed method does not use any external modulation or saturable absorber. Some of the signal's properties are discussed as well. 相似文献
969.
The paper discusses a likelihood based method of estimation which allows for a small amount of misspecification in the assumption of normality. Asymptotic results suggest that the new method can give an estimated model which is closer to the true model. An application to hearing threshold data is discussed. 相似文献
970.
The basic principle for the production of polarised thermal neutrons is discussed and the choice of various crystal monochromators
surveyed. Brief mention of broad-spectrum polarisers is made. The application of polarised neutrons to the study of magnetisation
density distributions in magnetic crystals, the dynamic concept of polarisation, principle and use of polarisation analysis,
the neutron spin-echo technique are discussed. 相似文献