This paper presents an improved scheme to compensate nonlinear phase path contamination when the backscattered signal propagates through the ionosphere in high-frequency skywave radar systems. The ionospheric variation often causes the spread of the ocean clutter spectrum in the frequency domain. The energy of the first-order component of ocean clutter dominates in Doppler spectrum, and thus it...

The Neumann-Neumann algorithm is known to be an e cient domain decomposition preconditioner with unstructured subdomains for iterative solution of nite element discretizations of di cult problems with strongly discontinuous coe cients [6]. However, this algorithm su ers from the need to solve in each iteration an inconsistent singular problem for every subdomain, and its convergence deteriorate...

This paper deals with the time-frequency characteristic analysis for track geometry irregularities using field data recorded by a comprehensive inspection train. The parameters of gauge and left right rail alignment are considered to identify their wavelengths locations waveforms. In addition conventional time frequency domain analysis, auto-adaptive signal decomposition techniques used on four...

the analysis of geochemical data in frequency domain, as indicated in this research study, can provide new exploratory informationthat may not be exposed in spatial domain. to identify deep geochemical anomalies, sulfide zone and geochemical noises in dalli cu–au porphyry deposit, a new approach based on coupling fourier transform (ft) and principal component analysis (pca) has beenused. the re...

The present paper for the first time constructs a frame/dual frame pair of shearlet type such that both frames possess the distinctive time-frequency localization properties needed in establishing their desirable approximation properties. Our construction is based on a careful pasting together of two bandlimited shearlet Parseval frames associated with two different frequency cones, inspired by...

Overlapping domain decomposition methods are efficient and flexible. It is also important that such methods are inherently suitable for parallel computing. In this chapter, we will first explain the mathematical formulation and algorithmic composition of the overlapping domain decomposition methods. Afterwards, we will focus on a generic implementation framework and its applications within Diff...

The domain decomposition method embodies large potentials for a parallelization of FEM methods. In this data-parallel approach, the domain of interest is partitioned into smaller subdomains, either before the mesh generation or afterwards (mesh partitioning). The subdomains are assigned to processors that calculate the corresponding part of the approximation. The mesh decomposition and assignme...

In this talk we discuss the use of domain decomposition parallel iterative solvers for highly heterogeneous problems of flow in porous media, in both the deterministic and (Monte-Carlo simulated) stochastic cases. We are particularly interested in the case of highly unstructured coefficient variation where standard periodic or stochastic homogenisation theory is not applicable, and where there ...