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不连续介质反演的原对偶牛顿法和全变差正则化(英文)
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作者 冯立新 李媛 张磊 《黑龙江大学自然科学学报》 CAS 2018年第1期1-9,共9页
研究利用散射场测量数据反演非均匀介质的逆散射问题,特别是平面波在非均匀介质中传播时所产生逆散射问题的数值计算。为克服非均匀介质不连续变化和反演具有不适定性的困难,提出基于全变差正则化的原对偶牛顿方法,避免了一般正则化方... 研究利用散射场测量数据反演非均匀介质的逆散射问题,特别是平面波在非均匀介质中传播时所产生逆散射问题的数值计算。为克服非均匀介质不连续变化和反演具有不适定性的困难,提出基于全变差正则化的原对偶牛顿方法,避免了一般正则化方法对不连续介质交界处反演的过光滑性作用。数值试验显示,本算法可以在观测数据带有一定噪声的境况下有效地重构不连续介质系数。 展开更多
关键词 全变差正则化 原对偶牛顿法 逆介质散射
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二维有耗介质体电磁反演的时域玻恩迭代方法 被引量:1
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作者 余文华 彭仲秋 任朗 《微波学报》 CSCD 北大核心 1995年第2期97-103,共7页
本文利用时域非线性优化方法求解二维有耗介质体的逆散射问题获得了很好的结果.并对正散射的求解精度做了改进.
关键词 电磁散射 玻恩迭代 时域优化 介质散射
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Lump Solutions of Kadomtsev-Petviashvili I Equation in Non-uniform Media 被引量:1
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作者 朱晓明 张大军 陈登远 《Communications in Theoretical Physics》 SCIE CAS CSCD 2011年第1期13-19,共7页
N-lump solutions of the Kadomtsev-Petviashvili I equation in non-uniform media are derived through the inverse scattering transform. The obtained solutions describe lump waves with time-dependent amplitudes and veloci... N-lump solutions of the Kadomtsev-Petviashvili I equation in non-uniform media are derived through the inverse scattering transform. The obtained solutions describe lump waves with time-dependent amplitudes and velocities. Dynamics of l-lump wave and interactions of two lump wave are illustrated. 展开更多
关键词 non-isospectral Kadomtsev-Petviashvili I equation inverse scattering transform lump solutions
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Energetic Gamma Radiation from Blazar and Its Effect on Intergalactic Medium
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作者 Jayashri Medhi Hira Lal Duorah Anurup Gohain Barua Kalpana Duorah 《Journal of Earth Science and Engineering》 2013年第3期203-206,共4页
Blazars are subclass of AGN (active galactic nuclei) with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about (10^44-10^47) erg/s. The γ-rays in the energy... Blazars are subclass of AGN (active galactic nuclei) with relativistic jet that is pointing in the general direction of the earth. The energy flux in the jet is about (10^44-10^47) erg/s. The γ-rays in the energy range 10 GeV-10 TeV emanating from blazar are examined and their effect on the IGM (intergalactic medium) is studied. The γ-ray emission is considered as due to inverse Compton scattering of relativistic electrons. There appears to be a gamma ray flux from blazar above 10 GeV having a line intensity of 1.5 × 10^-4 cm^-2 s^-1 sr^-1. The IGM is measured to large distances and it is found to be clumpy. It is found that at higher redshifl the density of IGM increases. The cosmological density parameter measured is found to lie within the suggested limit of 0.03 at redshift z = 3 for background intensity of radiation 10^-24 W·m^-2·Hz^-1·sr^-1. The iso-ΩIGM curve shows a kink in its profile which might be significant at the particular value of z equal to 2. Some more detailed studies are required for understanding the distribution of intergalactic medium at the unstable point at z = 2 as shown in inverse Compton radiation. 展开更多
关键词 Active galactic nuclei gamma rays intergalactic medium.
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