Results 261 to 270 of about 270,101 (314)

Periodic structures in waveguides

Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2002
Summary: We consider structures of period 2 spanning a two-dimensional waveguide of width \(2N\). Scattering problems, where Neumann conditions are imposed on the boundary of the structure and either Neumann or Dirichiet conditions are applied on the guide walls, are decomposed into \(N+1\) independent problems.
Linton, C. M., McIver, M.
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Detecting periodic structure

Proceedings. Fourteenth International Conference on Pattern Recognition (Cat. No.98EX170), 2002
We present a method for the detection of periodic structure in images. Finding a global threshold to detect a significant frequency component, and then associating it with responsible features, is fragile. The method extracts features from the original signal, and uses their autocorrelation as the basis for an adaptive filter, with which they are ...
James Orwell, James F. Boyce, John F. Haddon, Gregory H. Watson   +3 more
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Time series with periodic structure

Biometrika, 1967
Time series which are encountered in meteorology exhibit non-stationary behaviour. If a variable is observed at the same time each day, it appears to be stationary over a period of a few weeks, but there is a seasonal variation in structure (Monin, 1963). For example, the mean and spectral density are different in the summer and in the winter.
Jones, Richard H., Brelsford, William M.
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Dynamics of Periodic and Near-Periodic Structures

Applied Mechanics Reviews, 1992
A brief review of linear waves and dynamic behavior of both periodic and near-periodic structures is presented in this paper. Emphasis is placed on a summary of more recent studies of engineering structures subject to wave motion and the effects of near-periodicity on their dynamic behavior.
Dong Li, Haym Benaroya
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Periodic doping structure in GaAs

Progress in Crystal Growth and Characterization, 1979
Abstract A new type of superlattice consisting of a periodic sequence of ultrathin p- and n- doped semiconductor layers, possibly with intrinsic (i-) layers in between, is considered. In addition to the features related to the subband formation, as known from the study of the familiar heterostructure superlattices of the type GaxAl1−xAs, crystals ...
G.H. Döhler, K. Ploog
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Flow acoustics in periodic structures

Ultrasonics, 2005
A recent paper [A.A. Krokhin, J. Arriaga, L.N. Gumen, Speed of sound in periodic elastic composites, Phys. Rev. Lett. 91 (2004) 264302-1-4] addresses the speed of sound in periodic elastic composites (phononic crystals) with particular emphasis to the case where air bubbles are present in water and arranged periodically.
Willatzen, Morten, Lew Yan Voon, L.C.
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Multidimensional period doubling structures

Acta Crystallographica Section A Foundations and Advances, 2016
This paper develops the formalism necessary to generalize the period doubling sequence to arbitrary dimension by straightforward extension of the substitution and recursion rules. It is shown that the period doubling structures of arbitrary dimension are pure point diffractive. The symmetries of the structures are pointed out.
Jeong Yup, Lee, Dvir, Flom, Shelomo I, Ben-Abraham   +2 more
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Quasi-periodic Structures

1997
Periodic structures play an important role in the interaction of electrons with waves since they support harmonics of phase-velocity smaller than \( c \) and with an adequate design, this velocity can be set equal to the average velocity of the electrons.
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