Random Field and Stochastic Process

Author(s):  
Takeyuki Hida ◽  
Si Si

There is a famous formula called Lévy's stochastic infinitesimal equation for a stochastic process X(t) expressed in the form [Formula: see text] We propose a generalization of this equation for a random field X(C) indexed by a contour C. Assume that the X(C) is homogeneous in a white noise x, say of degree n, we can then appeal to the classical theory of variational calculus and to the modern theory of white noise analysis in order to discuss the innovation for the X(C) and hence its probabilistic structure. Some of future directions are also mentioned.


Author(s):  
SI SI

We shall first establish a canonical representation of a Gaussian random field X(C) indexed by a smooth contour C in terms of two-dimensional parameter white noise. Then, we take a nonlinear function F(X(C)) of the X(C) and obtain its variation when C deforms slightly. The variational formula is analogous to the Ito formula for a stochastic process X(t), but somewhat simpler.


1976 ◽  
Vol 13 (2) ◽  
pp. 276-289 ◽  
Author(s):  
Robert J. Adler

For an n-dimensional random field X(t) we define the excursion set A of X(t) by A = [t ∊ S: X(t) ≧ u] for real u and compact S ⊂ Rn. We obtain a generalisation of the number of upcrossings of a one-dimensional stochastic process to random fields via a characteristic of the set A related to the Euler characteristic of differential topology. When X(t) is a homogeneous Gaussian field satisfying certain regularity conditions we obtain an explicit formula for the mean value of this characteristic.


2008 ◽  
Vol 49 (4) ◽  
pp. 533-541 ◽  
Author(s):  
MI-HWA KO ◽  
HYUN-CHULL KIM ◽  
TAE-SUNG KIM

AbstractFor a linear random field (linear p-parameter stochastic process) generated by a dependent random field with zero mean and finite qth moments (q>2p), we give sufficient conditions that the linear random field converges weakly to a multiparameter standard Brownian motion if the corresponding dependent random field does so.


1976 ◽  
Vol 13 (02) ◽  
pp. 276-289 ◽  
Author(s):  
Robert J. Adler

For an n-dimensional random field X(t) we define the excursion set A of X(t) by A = [t ∊ S: X(t) ≧ u] for real u and compact S ⊂ Rn. We obtain a generalisation of the number of upcrossings of a one-dimensional stochastic process to random fields via a characteristic of the set A related to the Euler characteristic of differential topology. When X(t) is a homogeneous Gaussian field satisfying certain regularity conditions we obtain an explicit formula for the mean value of this characteristic.


1996 ◽  
Vol 9 (4) ◽  
pp. 531-549
Author(s):  
Pál Révész

At time t=0 we have a Poisson random field on ℝd. Each particle executes a critical branching Wiener process starting from its position at time t=0. Let RT be the radius of the largest ball around the origin of ℝd which does not contain any particle at time T. Our goal is to characterize the properties of the stochastic process {RT,T≥0}.This article is dedicated to the memory of Professor Roland L. Dobrushin.


1975 ◽  
Vol 7 (01) ◽  
pp. 140-153
Author(s):  
David A. Swick

Multidimensional sampling of real data, e.g., in space and time, often requires observations at non-uniformly spaced intervals. A discrete transform of a multidimensional stationary stochastic process transforms a multivariate problem into an asymptotically univariate one if the spacing is uniform in at least one dimension. For both uniform and non-uniform sampling and a model of ‘signal’ imbedded in a ‘noise’ process, asymptotic normality and independence justifies statistical testing in each cell of the transformed domain of the hypothesis ‘noise alone’ versus the alternate ‘signal plus noise’.


1975 ◽  
Vol 7 (1) ◽  
pp. 140-153
Author(s):  
David A. Swick

Multidimensional sampling of real data, e.g., in space and time, often requires observations at non-uniformly spaced intervals. A discrete transform of a multidimensional stationary stochastic process transforms a multivariate problem into an asymptotically univariate one if the spacing is uniform in at least one dimension. For both uniform and non-uniform sampling and a model of ‘signal’ imbedded in a ‘noise’ process, asymptotic normality and independence justifies statistical testing in each cell of the transformed domain of the hypothesis ‘noise alone’ versus the alternate ‘signal plus noise’.


2014 ◽  
Vol 30 (3) ◽  
pp. 229-239 ◽  
Author(s):  
J. Ching ◽  
C.-J. Lin

ABSTRACTThis paper shows that the mobilized shear strength of a two-dimensional (2-D) spatially variable saturated undrained clay is closely related to the extreme value of a one-dimensional (1-D) continuous stationary stochastic process. This 1-D stochastic process is the integration of the 2-D spatially variable shear strength along potential slip curves. Based on this finding, a probability distribution model for the mobilized shear strength of the 2-D clay is developed based on a probability distribution model for the extreme value of the 1-D stochastic process. The latter (the model for the 1-D extreme value) has analytical expressions. With the proposed probability distribution model, the mobilized shear strength of a 2-D clay can be simulated without the costly random field finite element analyses.


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