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A wavelet-based algorithm to estimate ocean wave parameters from radar images / A. Niedermeier in IEEE Transactions on geoscience and remote sensing, vol 43 n° 2 (February 2005)  

Public [article]  inIEEE Transactions on geoscience and remote sensing > vol 43 n° 2 (February 2005) . - pp 327 - 336 Titre : A wavelet-based algorithm to estimate ocean wave parameters from radar images Type de document : Article/Communication Auteurs : A. Niedermeier, Auteur ; J.C.N. Borge, Auteur ; et al., Auteur Année de publication : 2005 Article en page(s) : pp 327 - 336 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image [Termes IGN] image ERS-SAR [Termes IGN] océan [Termes IGN] ondelette [Termes IGN] surface de la mer [Termes IGN] système non linéaire [Termes IGN] vague Résumé : (Auteur) In recent years, new remote sensing techniques have been developed to measure two-dimensional (2-D) sea surface elevation fields. The availability of these data has led to the necessity to extend the classical analysis methods for one-dimensional (1-D) buoy time series to two dimensions. This paper is concerned with the derivation of group parameters from 2-D sea surface elevation fields using a wavelet-based technique. Wave grouping is known to be an important factor in ship and offshore safety, as it plays a role in dangerous resonance phenomenons and the generation of extreme waves. Synthetic aperture radar (SAR) data are used for the analysis. The wavelet technique is introduced using synthetic ocean surfaces and simulated SAR data. It is shown that the group structure of the ocean wave field can be recovered from the SAR image if the nonlinear imaging effects are moderate. The method is applied to a global dataset of European Remote Sensing satellite (ERS-2) wave mode data. Different group parameters including the area covered by the largest group and the number of groups in a given area are calculated for over 33 000 SAR images. Global maps of the parameters are presented. For comparison, classical 1D grouping parameters are calculated from colocated wave model data showing good overall agreement with the wavelet-derived parameters. ERS-2 image mode data are used to study wave fields in coastal areas. Waves approaching the island of Sylt in the North Sea are investigated, showing the potential of the wavelet technique to analyze the spatial wave dynamics associated with the bottom topography. Observations concerning changes of wavelength and group parameters are compared to linear wave theory. Numéro de notice : A2005-101 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1109/TGRS.2004.836873 En ligne : https://doi.org/10.1109/TGRS.2004.836873 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=77433 [article]

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065-05021	RAB	Revue	Centre de documentation	En réserve L003	Disponible

Zur Bestimmung des Erdschwerefeldes unter Verwendung des Maximum-Entropie-Prinzips / Rüdiger Lehmann (1994)

Public Titre : Zur Bestimmung des Erdschwerefeldes unter Verwendung des Maximum-Entropie-Prinzips Titre original : [Sur la détermination du champ de pesanteur terrestre en utilisant le principe d'entropie maximale] Type de document : Thèse/HDR Auteurs : Rüdiger Lehmann, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1994 Collection : DGK - C Sous-collection : Dissertationen num. 425 Importance : 103 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9468-0 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Géodésie physique [Termes IGN] Baltique, mer [Termes IGN] champ de pesanteur local [Termes IGN] distribution de Gauss [Termes IGN] entropie [Termes IGN] harmonique sphérique [Termes IGN] levé gravimétrique [Termes IGN] méthode de Monte-Carlo [Termes IGN] problème inverse [Termes IGN] système non linéaire Index. décimale : 30.40 Géodésie physique Résumé : (Auteur) The thesis deals with the problem of determining the outer gravity field of the Earth based on a finite number of data affected by measurement errors. It is described as a discrete inverse problem in an informational framework suggested by Tarantola and Valette (1982). Based on a conjunction operation for different states of information, a very general solution scheme for such problems is provided. For the first time we give a complete axiomatic foundation of this operation. The mainstay of this work is the application of the solution scheme to the problem of modelling the disturbing potential in the outer space of the Earth. It is necessary to extend the scheme to account for unknown variance components, namely the squares of the unavoidable modellization errors. The result is not immediately a spatial potential function, but a state of information for the value of the disturbing potential at any point in the outer space, being the result of the conjunction of the states of information available. The solution scheme does not suggest a certain type of model for the representation of the potential, e.g. spherical harmonics could be used. Here the method of point masses in free (optimized) positions serves as an illustrating example. For the definition of the probability distributions used we exclusively rely on the maximum entropy principle. This gives the least informative state of information consistent with given constraints. In this context the problem of constructing probability distributions for mass anomalies inside the Earth subject to spectral constraints for the outer gravity field is treated. The solution is presented for point mass anomalies and a number of practically occuring spectral constraints, both on a sphere as well as in a tangential plane. In general, the probability distributions finally obtained for the representation of the state of information on the disturbing potential cannot be expressed analytically, because a multidimensional integral is not analytically tractable. However, two special cases exist, where an analytical solution is possible. Then we obtain either a t-distribution or a normal distribution for the disturbing potential value, both very well suited for estimation. In the remaining cases the resulting probability distributions can only be described by means of characteristic parameters. First of all, we investigate both the expectation as well as the mode (maximum likelihood point). Again, as the multidimensional integrals involved have no analytical solution, both can in general not be computed directly. Without numerical integration only the joint mode over the space of model parameters, modellization error squares, and the disturbing potential can be computed. This is accomplished by solving a nonlinear equation system. If any, only the method of Monte Carlo integration is powerful enough to provide numerical approximates for the multidimensional integrals to be evaluated. The crucial point here is the proper choice of the pseudorandom distributions. For truely large dimension numbers even expensively determined pseudorandom distributions fall short. In a simple synthetic simulation study we compute marginal probability distributions for model parameters, for the modellization errors as well as for the disturbing potential by means of the Monte Carlo integration technique. In a larger scale simulation example, modelled close to the real behaviour of the gravity field in the Gulf of Bothnia, we try to assess biases of the maximum likelihood estimate. The Monte Carlo integration as well as the average second order remainder assessment do not agree well. Here the only conclusion to be drawn is: The biases do not form the largest constituent of the posterior errors in the results. Finally we compute a local gravity field based on real data on the Gulf of Bothnia. We process more than 11000 gravimetric and more than 900 altimetric data. The results are two maximum likelihood solutions for up to 750 point masses in free positions. The first is based exclusively on the gravimetric data. The predicted geoid fits the altimetrically surveyed sea surface within 11 cm, that is not much more than the actual error of the altimetry. The second solution also includes the altimetry. Unlike the original method of point masses in free positions, we are now able to handle problems with different types of data, different data accuracies, as well as inhomogeneous spatial data coverage. This indicates the power of the suggested approach. Numéro de notice : 28063 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=63410

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
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28063-02	30.40	Livre	Centre de documentation	Géodésie	Disponible

Optimierung geodätischer Netze mit spektralen Zielfunktionen / H. Kaltenbach (1992)

Public Titre : Optimierung geodätischer Netze mit spektralen Zielfunktionen Titre original : [Optimisation des réseaux géodésiques par les fonctions spectrales recherchées] Type de document : Thèse/HDR Auteurs : H. Kaltenbach, Auteur Editeur : Munich : Bayerische Akademie der Wissenschaften Année de publication : 1992 Collection : DGK - C Sous-collection : Dissertationen num. 393 Importance : 116 p. Format : 21 x 30 cm ISBN/ISSN/EAN : 978-3-7696-9439-0 Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] analyse spectrale [Termes IGN] canevas [Termes IGN] itération [Termes IGN] matrice de covariance [Termes IGN] mire parlante [Termes IGN] problème inverse [Termes IGN] réseau géodésique [Termes IGN] système de coordonnées [Termes IGN] système non linéaire [Termes IGN] valeur propre Index. décimale : 30.10 Systèmes de référence et réseaux géodésiques Résumé : (Auteur) The following thesis deals with the optimization of geodetic networks based on spectral target functions. The spectral analysis and optimization is based on the decomposition of the normal equation matrix of the adjustment or on the covariance matrix of the coordinates in the system of eigenvalues and eigenvectors. Chapter two contains some important mathematical background knowledge from the field of direct and inverse eigenvalue problems and the iterative solution of nonlinear systems of equations. Especially some properties of the newton-procedure are discussed, because this method is generally used to solve inverse eigenvalue problems. To apply the Newton-procedure it is necessary to know the derivatives of the eigenvalues and vectors of the considered matrix with respect to the design parameters. The derivatives of an arbitrary (symmetric) matrix are summarized in this chapter. The spectral analysis of geodetic networks related to aspects of precision and reliability is the subject of chapter three. Some wellknown local and global measures for the precision are summarized shortly. Aspects concerned with the so-called inner geometry of a network and the definition of the coordinate system (datum problem) are mentioned and supplemented by examples. The optimization with target functions related to the eigenvalue spectrum is the main part of this thesis and the subject analyzed in detail in chapter four. Principally spoken the task is to determine the coordinates of the netpoints and the observation weights in such a manner that the resulting normal equation or covariance matrix has a special target spectrum. This is the definition of the inverse eigenvalue problem. Based on a given start design of a geodetic network the target function is formulated and the inverse eigenvalue problem is solved iteratively. As mentioned above it is necessary to know the derivatives of the eigenvalues with respect to the coordinates and the observation weights. The derivatives can be computed based on the eigenvalue problem for the normal equation matrix or the covariance matrix and furthermore it is necessary to calculate the derivatives of the elements of the normal equation matrix analytically. Problems arising in network optimization like handling the orientation unknowns in direction networks or the consideration of inner geometry and datum definition of a network are discussed. Examples show the effectiveness of the optimization procedure and show how the so-called weak form of geodetic networks can be reduced. The spectral network optimization is a useful tool for understanding properties and behaviour of geodetic networks. The spectral formulation with target eigenvalues allows the solution of first, second and third order design problems in the usual classification of network optimization. The examples are also used to investigate the properties of the iterative solution procedure, especially the rate of convergence or the definiteness of solutions. In analogy to the eigenvalues, one can define an inverse eigenvector problem : the task is to determine the design parameters -namely the coordinates and the observation weights - in such a way that the normal equation matrix has given eigenvectors. The formulation of solution procedures and the difficulties in formulating suitable target functions for eigenvectors is the topic of chapter five. One application of this topic is the field of deformation analysis, where the task is to achieve the components of the dominant eigenvector in such a manner that they are perpendicular to. the expected direction of the deformations. To make an algorithm for network optimization a suitable tool in network planning, it is inevitable to consider some practical aspects. In the first order design, namely the determination of the coordinates of the netpoints, it is obvious that the rate of displacement of the points is limited by the local topography. One cannot move the points arbitrarily without loosing connections between the points. Therefore it is obvious to introduce the possible rate of displacement of the points as restrictions into the optimization algorithm. The same is valid for the observation weigths in a weight optimization (second order design). To take into account aspects of reliability we have to formulate upper bounds for the weights because observations with very high weights compared with other observations usually have low redundancy. Therefore in the adjustment gross errors can be found with a low probability, but unknown errors can distort the results significantly. If we take into account these practical aspects within the iterative solution procedure of the inverse eigenvalue problem we get a problem of minimizing a certain target function with additional restrictions in the form of equations and unequations. There are several methods in optimization theory for solving such problems. Chapter six of the present thesis deals with this topic. Again examples are used to supplement the theoretical investigations. Numéro de notice : 61414 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=60937

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
61414-01	30.10	Livre	Centre de documentation	Géodésie	Disponible
61414-02	30.10	Livre	Centre de documentation	Géodésie	Disponible

Analyse numérique / J. Baranger (1991)

Public Titre : Analyse numérique Type de document : Monographie Auteurs : J. Baranger, Auteur Editeur : Paris : Hermann Année de publication : 1991 Collection : Enseignement des sciences Importance : 556 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 2-7056-6093-2 Langues : Français (fre) Descripteur : [Vedettes matières IGN] Analyse numérique [Termes IGN] analyse numérique [Termes IGN] équation [Termes IGN] système linéaire [Termes IGN] système non linéaire Résumé : (Editeur) Synthèse des enseignements de huit universitaires, cet ouvrage présente la plupart des sujets classiques de l'analyse numérique. Il fait également une large place à des thèmes plus récents, souvent négligés mais indispensables aux différents utilisateurs puisque le calcul scientifique intervient désormais dans des domaines aussi variés que la mécanique, la physique, la chimie, la géologie, la biologie, les sciences de l'homme, etc. La complexité des calculs nécessaires à la simulation des phénomènes réels exige donc l'emploi d'ordinateurs puissants et de méthodes performantes. Cellesci sont proposées ici pour les grands thèmes d'application : équations différentielles, équations aux dérivées partielles, calcul des fréquences, identification et optimisation de paramètres, lissage de données, traitement du signal. Ce livre d'analyse numérique comporte deux parties. La première présente les connaissances de base et décrit en quatre chapitres les principaux problèmes et les méthodes associées : problème d'analyse numérique dans Rn, approximation des fonctions, résolution numérique des équations fonctionnelles, difficulté d'élaboration des programmes en fonction de la stabilité numérique et de l'influence des erreurs d'arrondi. La seconde partie se compose de sept chapitres écrits chacun par un spécialiste : résolution numérique des grands systèmes linéaires creux, résolution des grands systèmes non linéaires et méthodes d'optimisation sans contraintes, calcul de valeurs et vecteurs propres, lissage des données à l'aide des fonctions splines, approximation de Padé, transformation de Fourier discrète, équations différentielles raides. Chaque chapitre expose des résultats récents et fournit des algorithmes parmi les plus efficaces actuellement connus, ainsi que les principes de réalisation de logiciels performants qui leur correspondent. De nombreux exercices et thèmes de programme sont proposés. La structure de l'ouvrage, principalement destiné au niveau maîtrise et formation des ingénieurs, en fait un support idéal pour des cours de durée et de difficulté variées. Il sera de toute façon indispensable à tous les utilisateurs du calcul scientifique. Numéro de notice : 69472 Affiliation des auteurs : non IGN Thématique : MATHEMATIQUE Nature : Monographie Accessibilité hors numérique : Accessible à Georges Pérec (Id UGE) Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62205

Die Klotoide in der horizontalen Trassierungslinie : Verallgemeinerung der Trassierungsaufgabe mit einer Realisierung / Alajos Peter Krasnai (1989)  

Public Titre : Die Klotoide in der horizontalen Trassierungslinie : Verallgemeinerung der Trassierungsaufgabe mit einer Realisierung Titre original : [La clothoïde dans les lignes horizontales de trace, généralisation du problème de traçage avec sa réalisation] Type de document : Thèse/HDR Auteurs : Alajos Peter Krasnai, Auteur Editeur : Zurich : Institut für Geodäsie und Photogrammetrie IGP - ETH Année de publication : 1989 Collection : IGP Mitteilungen, ISSN 0252-9335 num. 045 Importance : 95 p. Format : 21 x 30 cm Note générale : Bibliographie Langues : Allemand (ger) Descripteur : [Vedettes matières IGN] Cartographie numérique [Termes IGN] alignement [Termes IGN] géométrie différentielle [Termes IGN] objet géographique linéaire [Termes IGN] réseau ferroviaire [Termes IGN] réseau géodésique tridimensionnel [Termes IGN] Suisse [Termes IGN] système non linéaire [Termes IGN] tracé automatique Résumé : (Auteur) In the planning of railway alignment lines there are problems of economical, dynamical and geometrical nature which must be solved. The scope of the present work is confined to the pure geometrical problems. For solving these, the methods that numerically imitate solving the problems with compass, straight-edge and spiral-ruler were refused, because the number of possible cases is too large to solve in an adequate time. To generalize and standardize, the methods of solving the geometrically possible problems concerned the alignment will be referred to as differential geometry. Starting from the natural equations of alignment elements (straight-lines, circles and spirals) through the choosing of the coefficients of integration, these elements will be embedded in the geodetic coordinate system. The restrictions of this embedding guided the author to the following principles, which have made it possible to generalize and standardize the pure geometrically problems of alignments: Each alignment element will be presented parametrically and the parameters will be regarded as unknown variables in the corresponding equations. The reality that the alignment line is a continuous sequence of alignment elements will be formulated by contact equations. All items that are known for the planning surveyors in the geometric task can be put in an explicit form of equations - as conditions -expressed by the unknown parameters and by the given items. Provided that the items are independent, the prepared equations are independent also. In the case that the items are dependent, new equations must be made up by means of the introduction of new unknown variables. The system of nonlinear equations can be handled by the introduction of characteristic variables for the unknown parameters and of an index table for the equations. Based on these principles, the numerical tools were established systematically. These tools guided the author to different types of tasks of constructions. There are tasks containing only one alignment element independent of other elements, and tasks concerning the alignment as a collection of alignment elements. The computer program LINPRO was developed by the Swiss Federal Railways observing special conventions. In this implementation the generated system of nonlinear equations are solved by means of various methods based on the theorem of fixed point of iteration. For the derivation of a point needed by this theorem, the given geometric items were primarily used, and secondarily, formulas derived from the dynamic of motions of trains. As an expansion of the current computer program, an interactive graphic system for developing horizontal alignment lines for the railways will be proposed. A three dimensional network with curved lines will be discussed as a further possible application of the elaborated principles. Numéro de notice : 27832 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Thèse étrangère DOI : 10.3929/ethz-a-000502186 En ligne : http://dx.doi.org/10.3929/ethz-a-000502186 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=56455

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Code-barres	Cote	Support	Localisation	Section	Disponibilité
27832-02	39.20	Livre	Centre de documentation	En réserve M-103	Disponible
27832-01	39.20	Livre	Centre de documentation	En réserve M-103	Disponible

Algorithmes numériques / J. Vignes (1980)

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Beiträge zur Erdgezeitenforschung des Arbeitskreises Geodäsie-Geophysik der Bundesrepublik Deutschland [Contributions à la recherche sur les marées terrestres du cercle de travail géodésie-géophysique de la RFA] / Manfred Bonatz (1979)

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Résolution du problème fondamental de la recherche opérationnelle (programme linéaire) par approximations quadratiques / Henri Marcel Dufour (1959)

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