Now showing items 1-20 of 42

    • A class of stationary random fields with a simple correlation structure 

      Ma, Chunsheng (Academic Press, 2004-07-15)
      A stationary random field is often more complicated than a univariate stationary time series, since dependence for a random field extends in all directions, while there is only the natural distinction of past and future ...
    • Binomial-chi(2) vector random fields 

      Ma, Chunsheng (SIAM Publ., 2017)
      We introduce a new class of non-Gaussian vector random fields in space and/or time, which are termed binomial-chi(2) vector random fields and include chi(2) vector random fields as special cases. We define a binomial-chi(2) ...
    • Covariance matrices for second-order vector random fields in space and time 

      Ma, Chunsheng (IEEE, 2011-05-01)
      This paper deals with vector (or multivariate) random fields in space and/or time with second-order moments, for which a framework is needed for specifying not only the properties of each component but also the possible ...
    • Covariance matrix functions of isotropic vector random fields 

      Wang, Renxiang; Du, Juan; Ma, Chunsheng (Taylor & Francis Group, 2014-05-15)
      An isotropic scalar or vector random field is a second-order random field in (d > 2), whose covariance function or direct/cross covariance functions are isotropic. While isotropic scalar random fields have been well developed ...
    • Covariance structures of Gaussian and log-Gaussian vector stochastic processes 

      Metheny, Maryssa (Wichita State University, 2012-12)
      Although the covariance structures of univariate Gaussian and log Gaussian stochastic processes have been extensively studied in the past few decades, the development of covariance structures for Gaussian and log-Gaussian ...
    • Hyperbolic cosine ratio and hyperbolic sine ratio random fields 

      Ma, Chunsheng (Elsevier, 2021-12)
      This paper introduces several vector random fields whose finite-dimensional characteristic functions are of hyperbolic type, including generalized logistic, hyperbolic secant, hyperbolic tangent, hyperbolic cosine ratio, ...
    • Hyperbolic vector random fields with hyperbolic direct and cross covariance functions 

      Du, Juan; Leonenko, Nikolai; Ma, Chunsheng; Shu, Hong (Taylor & Francis, 2012-06-26)
      This article introduces the hyperbolic vector random field whose finite-dimensional distributions are the generalized hyperbolic one, which is formulated as a scale mixture of Gaussian random fields and is thus an elliptically ...
    • Isotropic covariance matrix functions on all spheres 

      Ma, Chunsheng (Springer International Publishing AG, 2015-08)
      This paper reviews and introduces characterizations of the covariance function on all spheres that is isotropic and continuous, and characterizations of the covariance matrix function on all spheres whose entries are ...
    • Isotropic covariance matrix functions on compact two-point homogeneous spaces 

      Lu, Tianshi; Ma, Chunsheng (Springer, 2019)
      The covariance matrix function is characterized in this paper for a Gaussian or elliptically contoured vector random field that is stationary, isotropic, and mean square continuous on the compact two-point homogeneous ...
    • Isotropic covariance matrix polynomials on spheres 

      Ma, Chunsheng (Taylor & Francis Group, 2016)
      This article characterizes the covariance matrix function of a Gaussian or elliptically contoured vector random field that is stationary, isotropic, and mean square continuous on the sphere. By applying the characterization ...
    • Isotropic positive definite functions on spheres generated from those in Euclidean spaces 

      Nie, Zhihui (Wichita State University, 2019-05)
      In this thesis, author have reviewed the classical characterizations of isotropic positive definite functions on Euclidean spaces and spheres, and had applied them to develop a construction of isotropic positive de nite ...
    • Isotropic random fields with infinitely divisible marginal distributions 

      Wang, Fangfang; Leonenko, Nikolai; Ma, Chunsheng (Taylor & Francis, 2018)
      A simple but efficient approach is proposed in this paper to construct the isotropic random field in (d 2), whose univariate marginal distributions may be taken as any infinitely divisible distribution with finite variance. ...
    • Isotropic variogram matrix functions on spheres 

      Du, Juan; Ma, Chunsheng; Li, Yang (SPRINGER, 2013-04)
      This paper is concerned with vector random fields on spheres with second-order increments, which are intrinsically stationary and mean square continuous and have isotropic variogram matrix functions. A characterization of ...
    • K-combined random fields: Basic properties and stochastic orderings 

      Chen, Boming; Wang, Fangfang; Ma, Chunsheng (Taylor and Francis, 2021-05-17)
      This paper introduces the K-combined vector random field, whose finite-dimensional characteristic functions are made up of certain power functions and whose finite-dimensional density functions are comprised of the modified ...
    • K-differenced vector random fields 

      Alsultan, Rehab (Wichita State University, 2015-05)
      There is a great demand for analyzing multivariate measurements observed across space and over time, due to an increasing wealth of multivariate spatial, temporal, or spatio-temporal data, which may be treated as the ...
    • K-differenced vector random fields 

      Alsultan, Rehab; Ma, Chunsheng (SIAM Publ., 2019)
      A thin-tailed vector random field, referred to as a K-differenced vector random field, is introduced. Its finite-dimensional densities are the differences of two Besse! functions of second order, whenever they exist, and ...
    • K-distributed vector random fields in space and time 

      Ma, Chunsheng (Elsevier, 2013-04)
      This paper introduces two types of second-order vector random fields or stochastic processes whose marginals are K-distributed, through certain mixture procedures. The first type is formulated as an independent product of ...
    • Logistic vector random fields with logistic direct and cross covariances 

      Balakrishnan, N.; Ma, Chunsheng; Wang, Renxiang (Elsevier B.V., 2015-06)
      The logistic vector random field is introduced in this paper as a scale mixture of Gaussian vector random fields, and is thus a particular elliptically contoured (spherically invariant) vector random field. Such a logistic ...
    • Matched-pairs tests of homogeneity with applications to homologous nucleotide sequences 

      Ababneh, Faisal; Jermiin, Lars S.; Ma, Chunsheng; Robinson, John (Oxford University Press, 2006-05-15)
      Motivation: Most phylogenetic methods assume that the sequences of nucleotides or amino acids have evolved under stationary, reversible and homogeneous conditions. When these assumptions are violated by the data, there ...
    • Mittag-Leffler vector random fields with Mittag-Leffler direct and cross covariance functions 

      Ma, Chunsheng (Springer Heidelberg, 2013-10)
      In terms of the two-parameter Mittag-Leffler function with specified parameters, this paper introduces the Mittag-Leffler vector random field through its finite-dimensional characteristic functions, which is essentially ...