Linear combinations of space-time covariance functions and variograms

被引:49
|
作者
Ma, CS [1 ]
机构
[1] Wichita State Univ, Dept Math & Stat, Wichita, KS 67260 USA
关键词
covariance; Fourier transform; intrinsically stationary; isotropic; long-range dependence; power-law decay; spectral density; stationary; variogram;
D O I
10.1109/TSP.2004.842186
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
The difference or a linear combination of two spacetime covariance functions (or variograms) is not necessarily a valid covariance function (or variogram). In general, there seems no simple condition that makes a linear combination permissible, unless its coefficients are non-negative. The permissibility is investigated in this paper for the linear combination of two spatial or spatio-temporal covariance functions (or variograms) isotropic in space so that we obtain flexible classes of spatial or spatio-temporal covariance functions with various properties such as long-range dependence and having different signs.
引用
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页码:857 / 864
页数:8
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