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41.
The instability of field-aligned Whistler-mode waves in space plasmas is studied by using a recently developed generalized relativistic kappa-type (KT) distribution. Numerical calculations are performed for a direct comparison between the new KT distribution and the current kappa distribution. We show that the wave growth for the KT distribution tends to occur in the lower wave frequency (e.g.,ω 〈~0.1Ω) due to a larger fractional number of the resonant electrons ηrel (which controls the wave growth), while primarily locating in the higher wave frequency for the kappa distribution. Moreover, the relativistic anisotropy Are1 by the KT distribution is found to be smaller than that by the kappa distribution, leading to a smaller peak of wave growth. The results present a further understanding of plasma wave instability particularly in those plasmas where relativistic electrons are present. 相似文献
42.
在数学教学的过程中,我们常常会谈到"结构",那么,什么是"结构"呢?笔者认为,"结构"有两种,一种是我们熟悉的数学知识结构,这里"知识"之所以以"结构"的形式呈现,是因为知识都是建构的产物,如数学中的十进制;还有一种叫数学认知结构,它实际上是一种包含了个人理智洞见的知识,它也是通过建构完成的.这两种结构有何关系呢?简单点说,数学认知结构就是学生头脑中的数学知识结构,但它不会是知识结构在头脑中简单"复印"后的结果,而是学生 相似文献
43.
基于空间-频率的DOA估计研究 总被引:1,自引:0,他引:1
在阵列信号处理中,提取回波信号中的空间频率,可以得到目标的方位信息。该文正是利用小 波变换的时间-频率特性,对回波信号进行时间-空间处理,从而对目标方位进行了估计。文中给出了计算机仿真结果,并与基于短时傅里叶变换的估计结果进行了比较。 相似文献