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Extracting tidal frequencies using multivariate harmonic analysis of sea level height time series / Ali Reza Amiri-Simkooei in Journal of geodesy, vol 88 n° 10 (October 2014)  

Public [article]  inJournal of geodesy > vol 88 n° 10 (October 2014) . - pp 975 - 988 Titre : Extracting tidal frequencies using multivariate harmonic analysis of sea level height time series Type de document : Article/Communication Auteurs : Ali Reza Amiri-Simkooei, Auteur ; S. Zaminpardaz, Auteur ; M. Sharifi, Auteur Année de publication : 2014 Article en page(s) : pp 975 - 988 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] données marégraphiques [Termes IGN] fonction harmonique [Termes IGN] marée océanique [Termes IGN] niveau de la mer [Termes IGN] série temporelle Résumé : (Auteur) This contribution is seen as a first attempt to extract the tidal frequencies using a multivariate spectral analysis method applied to multiple time series of tide-gauge records. The existing methods are either physics-based in which the ephemeris of Moon, Sun and other planets are used, or are observation-based in which univariate analysis methods—Fourier and wavelet for instance—are applied to tidal observations. The existence of many long tide-gauge records around the world allows one to use tidal observations and extract the main tidal constituents for which efficient multivariate methods are to be developed. This contribution applies the multivariate least-squares harmonic estimation (LS-HE) to the tidal time series of the UK tide-gauge stations. The first 413 harmonics of the tidal constituents and their nonlinear components are provided using the multivariate LS-HE. A few observations of the research are highlighted: (1) the multivariate analysis takes information of multiple time series into account in an optimal least-squares sense, and thus the tidal frequencies have higher detection power compared to the univariate analysis. (2) Dominant tidal frequencies range from the long-term signals to the sixth-diurnal species interval. Higher frequencies have negligible effects. (3) The most important tidal constituents (the first 50 frequencies) ordered from their amplitudes range from 212 cm (M2) to 1 cm (OQ2) for the data set considered. There are signals in this list that are not available in the 145 main tidal frequencies of the literature. (4) Tide predictions using different lists of tidal frequencies on five different data sets around the world are compared. The prediction results using the first significant 50 constituents provided promising results on these locations of the world. Numéro de notice : A2014-516 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-014-0737-5 Date de publication en ligne : 29/06/2014 En ligne : https://doi.org/10.1007/s00190-014-0737-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=74120 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2014101	SL	Revue	Centre de documentation	Revues en salle	Disponible

Fast integer least-squares estimation for GNSS high-dimensional ambiguity resolution using lattice theory / S. Jazaeri in Journal of geodesy, vol 86 n° 2 (February 2012)  

Public [article]  inJournal of geodesy > vol 86 n° 2 (February 2012) . - pp 123 - 137 Titre : Fast integer least-squares estimation for GNSS high-dimensional ambiguity resolution using lattice theory Type de document : Article/Communication Auteurs : S. Jazaeri, Auteur ; Ali Reza Amiri-Simkooei, Auteur ; M. Sharifi, Auteur Année de publication : 2012 Article en page(s) : pp 123 - 137 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale [Termes IGN] analyse comparative [Termes IGN] données GNSS [Termes IGN] méthode des moindres carrés [Termes IGN] résolution d'ambiguïté Résumé : (Auteur) GNSS ambiguity resolution is the key issue in the high-precision relative geodetic positioning and navigation applications. It is a problem of integer programming plus integer quality evaluation. Different integer search estimation methods have been proposed for the integer solution of ambiguity resolution. Slow rate of convergence is the main obstacle to the existing methods where tens of ambiguities are involved. Herein, integer search estimation for the GNSS ambiguity resolution based on the lattice theory is proposed. It is mathematically shown that the closest lattice point problem is the same as the integer least-squares (ILS) estimation problem and that the lattice reduction speeds up searching process. We have implemented three integer search strategies: Agrell, Eriksson, Vardy, Zeger (AEVZ), modification of Schnorr–Euchner enumeration (M-SE) and modification of Viterbo-Boutros enumeration (M-VB). The methods have been numerically implemented in several simulated examples under different scenarios and over 100 independent runs. The decorrelation process (or unimodular transformations) has been first used to transform the original ILS problem to a new one in all simulations. We have then applied different search algorithms to the transformed ILS problem. The numerical simulations have shown that AEVZ, M-SE, and M-VB are about 320, 120 and 50 times faster than LAMBDA, respectively, for a search space of dimension 40. This number could change to about 350, 160 and 60 for dimension 45. The AEVZ is shown to be faster than MLAMBDA by a factor of 5. Similar conclusions could be made using the application of the proposed algorithms to the real GPS data. Numéro de notice : A2012-142 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-011-0501-z Date de publication en ligne : 30/07/2011 En ligne : https://doi.org/10.1007/s00190-011-0501-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=31589 [article]

Exemplaires(1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
266-2012021	RAB	Revue	Centre de documentation	En réserve L003	Disponible