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Periodic structures in waveguides
Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 2002Summary: 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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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 +3 more
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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 +3 more
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Time series with periodic structure
Biometrika, 1967Time 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, 1992A 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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Structure of Certain Periodic Rings
Canadian Mathematical Bulletin, 1985AbstractLet R be a periodic ring, N the set of nilpotents, and D the set of right zero divisors of R. Suppose that (i) N is commutative, and (ii) every x in R can be uniquely written in the form x = e + a, where e2 = e and a ∊ N. Then N is an ideal in R and R/N is a Boolean ring.
Abu-Khuzam, Hazar, Yaqub, Adil
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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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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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Periodic doping structure in GaAs
Progress in Crystal Growth and Characterization, 1979Abstract 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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Structures and Superstructures in Periodical Polynucleotides
1986A renewed attention has been focused on the structural aspects of DNA in the last few years. Such revival of interest starting from the elucidation of the structure of some synthetic oligonucleotides is going beyond toward the understanding of the basic molecular mechanisms of control of genetic information, which are strictly correlated to the ...
DE SANTIS, Pasquale +3 more
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A periodic structure mimics a metamaterial
Journal of the Optical Society of America A, 2007We show that properties attributed to planar metamaterials that support resonances due to an appropriately shaped unit cell can also be identified in a medium that exhibits a resonance evoked by its period only. By choosing a subwavelength period, the effective material parameters of such a medium can be retrieved from the complex reflected and ...
Rockstuhl, Carsten +2 more
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Flow acoustics in periodic structures
Ultrasonics, 2005A 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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