scholarly journals The expected behaviour of random fields in high dimensions: contradictions in the results of Bansal and Peterson (2018)

2021 ◽  
Author(s):  
Samuel Davenport ◽  
Thomas E. Nichols

AbstractBansal and Peterson (2018) found that in simple stationary Gaussian simulations Random Field Theory incorrectly estimates the number of clusters of a Gaussian field that lie above a threshold. Their results contradict the existing literature and appear to have arisen due to errors in their code. Using reproducible code we demonstrate that in their simulations Random Field Theory correctly predicts the expected number of clusters and therefore that many of their results are invalid.

2013 ◽  
Vol 50 (7) ◽  
pp. 723-734 ◽  
Author(s):  
H. Zhu ◽  
L.M. Zhang

In this study, anisotropic heterogeneous geotechnical fields are characterized using random field theory, in which five basic patterns of material anisotropy are simulated including isotropy, transverse anisotropy, rotated anisotropy, general anisotropy, and general rotated anisotropy. Theoretical formulations of scale of fluctuation as a function of directional angle are developed for the five basic patterns of anisotropy through modifications of the coordinate system. These formulations of scale of fluctuation are identical for different correlation structures. Correlation functions for the exponential and Gaussian correlation structures are also derived. The matrix decomposition method is then applied to generate anisotropic random fields. The generated random field correlated data are verified with two realizations of transverse anisotropy and general rotated anisotropy random fields. Test values of the sample mean, sample deviation, and scales of fluctuation in six directions match well with the prescribed values. This study provides a technique to characterize inherent geotechnical variability and anisotropy, which is required to realistically simulate complex geological properties in engineering reliability analysis and design.


NeuroImage ◽  
2004 ◽  
Vol 23 ◽  
pp. S189-S195 ◽  
Author(s):  
Keith J. Worsley ◽  
Jonathan E. Taylor ◽  
Francesco Tomaiuolo ◽  
Jason Lerch

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