Contribution of nuclei accelerated by gamma-ray pulsars to cosmic rays in the Galaxy     

W. Bednarek  R. J. Protheroe   《Astroparticle Physics》2002,16(4):1076-409

We consider the galactic population of gamma-ray pulsars as possible sources of cosmic rays at and just above the “knee” in the observed cosmic ray spectrum at 10¹⁵–10¹⁶ eV. We suggest that iron nuclei may be accelerated in the outer gaps of pulsars, and then suffer partial photo-disintegration in the non-thermal radiation fields of the outer gaps. As a result, protons, neutrons, and surviving heavier nuclei are injected into the expanding supernova remnant. We compute the spectra of nuclei escaping from supernova remnants into the interstellar medium, taking into account the observed population of radio pulsars.

Our calculations, which include a realistic model for acceleration and propagation of nuclei in pulsar magnetospheres and supernova remnants, predict that heavy nuclei accelerated directly by gamma-ray pulsars could contribute about 20% of the observed cosmic rays in the knee region. Such a contribution of heavy nuclei to the cosmic ray spectrum at the knee can significantly increase the average value of lnA with increasing energy as is suggested by recent observations.  相似文献   

类星体3C286结构中的谱指数分布     

张福俊 《天文学报》1995,36(2):115-119

由５ＧＨｚ和１．６６ＧＨｚ的ＶＬＢＩ全球阵观测，我们获得类星体３Ｃ２８６在该两频率上的高动态范围的毫角秒尺度的图像和谱指数在结构中的分布状况。从谱指数，我们无法判断该源中央两个子源中哪一个真正的核。我们排队３Ｃ２８６的结构是由引力透镜所形成的像的可能性。也许在该源的中央存在两个黑洞，即两个中央“引擎”，每一个有它自己的、向不同方向延伸的喷流。  相似文献   

应用沃尔什函数讨论我国旱涝时空变化   总被引：1，自引：0，他引：1  

唐佑民 《地理学报》1989,44(4):420-428

本文在文献基础上，应用沃尔什函数理论中的沃氏变化系数物理意义，讨论了我国东部（100°E以东）旱涝的时、空变化，得出了8种旱涝型和1470－1981年全国旱涝型年表。在这基础上，比较了沃氏功率谱与付氏功率谱的计算结果。研究表明：沃尔付函数在分析矩形数字波气象问题时，比傅氏函数有着更好的适用性和优越性。  相似文献   

火烧迹地信息遥感快速提取方法研究     

高中灵  汪小钦  周小成 《国土资源遥感》2005,(4):38-41,i0002

利用福建省福州地区ETM图像，在分析火烧迹地光谱特征的基础上，研究了火烧迹地信息遥感快速提取方法。文中设置了4种提取方案，即监督分类法、NDVI参与的监督分类法、NDVI差值法及谱间关系法，最后，对提取结果进行了精度评价。  相似文献   

多维分形奇异功率谱分析与应用          下载免费PDF全文

李庆谋;  ;  刘少华; 《地球物理学进展》2005,20(4)

地球物理信号中普遍含有噪声，消除噪声是地球物理信号处理中的关键技术之一.奇异功率谱分析（SSA）是在状态空间（又称相空间）中研究（系统）动力学、非线性科学与混沌现象的方法.本文在状态空间中通过SSA分解，研究、应用地球物理序列的尺度不变性进行多维分形滤波：通过在状态空间的SSA分解，构造了经验正交函数系（EOF）；在EOF子空间中定义了两种尺度与测度后，发现了两种测度与尺度皆在多个尺度范围内存在尺度不变性；利用这种尺度~测度的尺度不变性，设计、实现了多维分形奇异功率谱(MSSA)滤波模型；处理解释了大洋钻探（ODP）1143A孔岩芯自然反射性（NGR）资料；Fourier功率谱分析结果证明，MSSA能有效地压制噪声，提取有用信号.研究得出，嵌入维数对MSSA基本无影响（小于1/1000），多维分形滤波器（MSSA）能有效压制噪声或提取有用信号.  相似文献   

校园典型地物波谱特性数据库系统研究     

陈香菱  张振勇  董健  任朋飞 《国土资源信息化》2007,(6):23-24,25

通过对山东科技大学若干典型地物如植被、水体、岩石的波谱特征测定、波谱图像处理,获得了较详细的地物波谱数据。结合当前地物波谱的研究现状及成果,建立了一个便于查询山东科技大学地物波谱特性的数据库系统。同时研究了地物波谱的动态变化规律,为进一步遥感数据分类等应用提供基础数据,为学生进行遥感实验提供基础资料。  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987113000613     

Yangfan Deng  Zhongjie Zhang  Weiming Fan  Marta Perez-Gussinye 《地学前缘(英文版)》2014,5(2):193-203

The effective elastic thickness （Te） represents the thickness of the elastic layer or the flexural rigidity of the lithosphere, the equivalent of which can be calculated from the spectral analysis of gravity and topographic data. Studies of Te have profound influence on intracontinental deformation, and coupling of the tectonic blocks. In this paper, we use the multitaper spectral estimation method to calculate the coherence between Bouguer gravity and topography data, and to obtain the Te map of South China. Through the process of correction, we discuss the relationships of Te versus heat flow, and Te versus seismicity. The results show that Te distribution of South China is affected by three factors：the original age, which controls the basic feature;the Mesozoic evolution, which affects the Te distribution;and the neotectonic movement, which shaped the final distribution. The crust age has a positive correlation with the first-order Te distribution;thus the Yangtze Craton has a relatively higher Te （about 50 km） whereas the Te in Cathaysia block is only 10e20 km. By analysis and comparison among the tectonic models of South China, the Te distribution can be well explained using the flat-subduction model. As is typical with neotectonics, the region with a higher heat flow is related with a lower Te. The seismicity does not have a clear relationship with Te, but the strong seismicity could cause a low Te. Seismogenic layer （Ts） has a similar trend as Te in the craton, whereas in other areas the relationship is complex.  相似文献   

Stochastic significance of peaks in the least-squares spectrum   总被引：3，自引：1，他引：2  

S. D. Pagiatakis 《Journal of Geodesy》1999,73(2):67-78

The least-squares spectral analysis method is reviewed, with emphasis on its remarkable property to accept time series with an associated, fully populated covariance matrix. Two distinct cases for the input covariance matrix are examined: (a) it is known absolutely (a-priori variance factor known); and (b) it is known up to a scale factor (a-priori variance factor unknown), thus the estimated covariance matrix is used. For each case, the probability density function that underlines the least-squares spectrum is derived and criteria for the statistical significance of the least-squares spectral peaks are formulated. It is shown that for short series (up to about 150 values) with an estimated covariance matrix (case b), the spectral peaks must be stronger to be statistically significant than in the case of a known covariance matrix (case a): the shorter the series and the lower the significance level, the higher the difference becomes. For long series (more than about 150 values), case (b) converges to case (a) and the least-squares spectrum follows the beta distribution. The results of this investigation are formulated in two new theorems. Received: 27 May 1997/Accepted: 30 September 1998  相似文献   

风浪频谱的成长模型Ⅰ.谱参量随风区的增长关系          下载免费PDF全文

王鑫  侯一筠 《海洋与湖沼》2008,39(5):433-438

为得到谱参量随风区的变化关系,从而更细致地刻画风浪频谱的成长方式.在动力学方程的控制下,基于三参量风浪频谱,利用动力-统计学相结合的方法导出了谱参量(谱宽度B、谱的零阶矩～m0、谱的峰频率～ω0)随风场要素(风区)的成长关系分别为:B=5.68×10-3～X9.482×10-1-4.66×10-2ln-x;～m0=1.356×10-8～x2.367-1.097×10-1ln～x;～ω=4.082×101～X-7.623×10-1+3.71×10-2ln～x.同时得到了简化形式的波陡δ、波龄β与谱宽度之间的关系为:δ=2.14×10-2B-1.05-4.26×10-1lnB,β=1.26B1.28+1.97×10-1ln(B).此外,还得出了受风场要素控制的,谱的零阶矩与谱的峰频率之间新关系为:{ω0=a1～m0-0.33 a1=1.034×10-1～X1.872×10-2+8.50×10-4ln～x,从而阐明了先前的各种经验关系是新关系在取不同风区值时的特例.可见,将动力学原理引入风浪频谱的研究,所建立的谱参量随风区的变化关系与先前的经验公式相比更加合理,且普适性更强.  相似文献   

用T-矩阵法分析降水粒子在微波段下的Z_(DR)特性     

陈康  王庆安 《气象科学》2000,20(4)

本文采用Ｔ－矩阵方法从理论计算的角度分析了在Ｘ、Ｃ和Ｓ波段下不同轴比、大小和相态的扁椭球降水粒子的差反射率因子ＺＤＲ,对为三种波长的双线偏振雷达实际运用提出了更合理的解释,得到若干有用的结论。文中还对Ｔ－矩阵方法的准确性进行地评价。  相似文献