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Fast ambiguity resolution for long-range reference station networks with ionospheric model constraint method / Ming Zhang in GPS solutions, vol 21 n° 2 (April 2017)
[article]
Titre : Fast ambiguity resolution for long-range reference station networks with ionospheric model constraint method Type de document : Article/Communication Auteurs : Ming Zhang, Auteur ; Hui Liu, Auteur ; Zhengdong Bai, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 617 – 626 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie spatiale
[Termes IGN] antenne GNSS
[Termes IGN] erreur
[Termes IGN] modèle ionosphérique
[Termes IGN] résolution d'ambiguïté
[Termes IGN] retard ionosphèrique
[Termes IGN] station de référenceRésumé : (auteur) Ambiguity resolution (AR) speed is one of the most important performance indicators of a network RTK (real-time kinematics) system. Given the low correlation between the error sources of two stations, the effect of the atmospheric delay of double-difference observations cannot be ignored, thus making it difficult to fix the ambiguities. Ionospheric delay is one of the largest error sources affecting AR. This error source is reduced by the ionospheric-free combination with traditional methods. The AR speed of these methods is slow; generally, tens of minutes and even more are required for initialization. This study proposes an ionospheric model constraint (IMC) method to improve the AR speed. External information is not required apart from observations. The double-difference ionospheric delay is described with a regional double-difference ionospheric model, the coefficients of which are estimated as parameters together with ambiguities and tropospheric delays. Experimental results show that the initialization speed significantly improves by 72.5 % and that the AR speed for the newly risen satellites increases by 84.3 % with the proposed IMC method. Furthermore, the percentage of correctly fixed integer ambiguities after initialization increases to some extent. Numéro de notice : A2017-215 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1007/s10291-016-0551-z En ligne : http://dx.doi.org/10.1007/s10291-016-0551-z Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85087
in GPS solutions > vol 21 n° 2 (April 2017) . - pp 617 – 626[article]On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation / Tao Jian in Journal of geodesy, vol 90 n° 12 (December 2016)
[article]
Titre : On the spectral combination of satellite gravity model, terrestrial and airborne gravity data for local gravimetric geoid computation Type de document : Article/Communication Auteurs : Tao Jian, Auteur ; Yan Ming Wang, Auteur Année de publication : 2016 Article en page(s) : pp 1405 - 1418 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] analyse harmonique
[Termes IGN] bruit blanc
[Termes IGN] champ de pesanteur terrestre
[Termes IGN] erreur
[Termes IGN] géoïde gravimétrique
[Termes IGN] géoïde local
[Termes IGN] Texas (Etats-Unis)
[Termes IGN] varianceRésumé : (Auteur) One of the challenges for geoid determination is the combination of heterogeneous gravity data. Because of the distinctive spectral content of different data sets, spectral combination is a suitable candidate for its solution. The key to have a successful combination is to determine the proper spectral weights, or the error degree variances of each data set. In this paper, the error degree variances of terrestrial and airborne gravity data at low degrees are estimated by the aid of a satellite gravity model using harmonic analysis. For higher degrees, the error covariances are estimated from local gravity data first, and then used to compute the error degree variances. The white and colored noise models are also used to estimate the error degree variances of local gravity data for comparisons. Based on the error degree variances, the spectral weights of satellite gravity models, terrestrial and airborne gravity data are determined and applied for geoid computation in Texas area. The computed gravimetric geoid models are tested against an independent, highly accurate geoid profile of the Geoid Slope Validation Survey 2011 (GSVS11). The geoid computed by combining satellite gravity model GOCO03S and terrestrial (land and DTU13 altimetric) gravity data agrees with GSVS11 to ±1.1 cm in terms of standard deviation along a line of 325 km. After incorporating the airborne gravity data collected at 11 km altitude, the standard deviation is reduced to ±0.8 cm. Numerical tests demonstrate the feasibility of spectral combination in geoid computation and the contribution of airborne gravity in an area of high quality terrestrial gravity data. Using the GSVS11 data and the spectral combination, the degree of correctness of the error spectra and the quality of satellite gravity models can also be revealed. Numéro de notice : A2016-810 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0932-7 En ligne : http://dx.doi.org/10.1007/s00190-016-0932-7 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=82602
in Journal of geodesy > vol 90 n° 12 (December 2016) . - pp 1405 - 1418[article]A systematic impact assessment of GRACE error correlation on data assimilation in hydrological models / Maike Schumacher in Journal of geodesy, vol 90 n° 6 (June 2016)
[article]
Titre : A systematic impact assessment of GRACE error correlation on data assimilation in hydrological models Type de document : Article/Communication Auteurs : Maike Schumacher, Auteur ; Jürgen Kusche, Auteur ; Petra Döll, Auteur Année de publication : 2016 Article en page(s) : pp 537 – 559 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] bassin hydrographique
[Termes IGN] corrélation
[Termes IGN] données GRACE
[Termes IGN] erreur
[Termes IGN] filtre de Kalman
[Termes IGN] gravimétrie
[Termes IGN] Mississippi (fleuve)
[Termes IGN] modèle hydrographiqueRésumé : (auteur) Recently, ensemble Kalman filters (EnKF) have found increasing application for merging hydrological models with total water storage anomaly (TWSA) fields from the Gravity Recovery And Climate Experiment (GRACE) satellite mission. Previous studies have disregarded the effect of spatially correlated errors of GRACE TWSA products in their investigations. Here, for the first time, we systematically assess the impact of the GRACE error correlation structure on EnKF data assimilation into a hydrological model, i.e. on estimated compartmental and total water storages and model parameter values. Our investigations include (1) assimilating gridded GRACE-derived TWSA into the WaterGAP Global Hydrology Model and, simultaneously, calibrating its parameters; (2) introducing GRACE observations on different spatial scales; (3) modelling observation errors as either spatially white or correlated in the assimilation procedure, and (4) replacing the standard EnKF algorithm by the square root analysis scheme or, alternatively, the singular evolutive interpolated Kalman filter. Results of a synthetic experiment designed for the Mississippi River Basin indicate that the hydrological parameters are sensitive to TWSA assimilation if spatial resolution of the observation data is sufficiently high. We find a significant influence of spatial error correlation on the adjusted water states and model parameters for all implemented filter variants, in particular for subbasins with a large discrepancy between observed and initially simulated TWSA and for north–south elongated sub-basins. Considering these correlated errors, however, does not generally improve results: while some metrics indicate that it is helpful to consider the full GRACE error covariance matrix, it appears to have an adverse effect on others. We conclude that considering the characteristics of GRACE error correlation is at least as important as the selection of the spatial discretisation of TWSA observations, while the choice of the filter method might rather be based on the computational simplicity and efficiency. Numéro de notice : A2016-422 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-016-0892-y Date de publication en ligne : 27/02/2016 En ligne : https://doi.org/10.1007/s00190-016-0892-y Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=81314
in Journal of geodesy > vol 90 n° 6 (June 2016) . - pp 537 – 559[article]Théorie des codes : compression, cryptage, correction / J. G. Dumas (2013)
Titre : Théorie des codes : compression, cryptage, correction Type de document : Guide/Manuel Auteurs : J. G. Dumas, Auteur ; J. L. Roch, Auteur ; S. Varrette, Auteur Mention d'édition : 2 Editeur : Paris : Dunod Année de publication : 2013 Collection : Sciences Sup Sous-collection : Informatique Importance : 372 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-2-10-059911-0 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Vedettes matières IGN] Télématique
[Termes IGN] analyse combinatoire (maths)
[Termes IGN] codage
[Termes IGN] compression de données
[Termes IGN] cryptographie
[Termes IGN] entropie
[Termes IGN] erreur
[Termes IGN] probabilités
[Termes IGN] théorème de Shannon
[Termes IGN] théorie de l'information
[Termes IGN] variable aléatoireRésumé : (Editeur) Transmettre des informations sous forme numérique suppose entre autres d'optimiser la taille des messages transmis pour éviter de surcharger les canaux de transmission, d'être capable de rectifier des erreurs apparues en cours de transmission, de crypter les contenus et d'authentifier les émissaires et les destinataires... L'originalité de cet ouvrage est de présenter tous les fondements mathématiques et informatiques sur lesquels reposent ces techniques. Les notions théoriques présentées sont illustrées par 120 exercices corrigés. Ce domaine évolue rapidement et cette 2e édition s'enrichit de compléments sur la cryptologie et sur les codes LDPC. Note de contenu : Introduction
Théorie des codes
- Codage par flots et probabilités
- Codage par blocs, algèbre et arithmétique
- Décoder, déchiffrer, attaquer
Théorie de l'information et compression
- Codage statistique
- Heuristiques de réduction d'entropie
- Codes compresseurs usuels
- La compression audio/video avec perte
Cryptologie
- Principes généraux et terminologie
- Attaques sur les systèmes cryptographiques
- Système cryptographique à clef secrète
- Système cryptographique à clef publique
- Authentification, intégrité, non-répudiation et signatures électroniques
- Protocoles usuels de gestion de clefs
Détection et corrections d'erreurs
- Principe de la détection et de la correction d'erreurs
- Détection d'erreurs par parité - codes CRC
- Distance d'un code
- Codes linéaires et codes cycliques
- Paquets d'erreurs et entrelacement
- Codes convolutifs et turbo-codes
Compression, cryptage, correction : en guise de conclusion
Solutions des exercices
Liste des figures, tables, algorithmes et acronymes utilisésNuméro de notice : 20942 Affiliation des auteurs : non IGN Thématique : INFORMATIQUE Nature : Manuel informatique Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=46969 Réservation
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Code-barres Cote Support Localisation Section Disponibilité 20942-01 26.50 Manuel Informatique Centre de documentation Informatique Disponible An adaptive method of non-stationary variogram modeling for DEM error surface simulation / Chuanfa Chen in Transactions in GIS, vol 16 n° 6 (December 2012)
[article]
Titre : An adaptive method of non-stationary variogram modeling for DEM error surface simulation Type de document : Article/Communication Auteurs : Chuanfa Chen, Auteur ; Yanyan Li, Auteur Année de publication : 2012 Article en page(s) : pp 885 - 899 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications photogrammétriques
[Termes IGN] diagramme de Voronoï
[Termes IGN] erreur
[Termes IGN] modèle numérique de terrain
[Termes IGN] Setchouan (Chine)
[Termes IGN] simulation de surface
[Termes IGN] variogrammeRésumé : (Auteur) Geostatistical characterization of local DEM error is usually based on the assumption of a stationary variogram model which requires the mean and variance to be finite and constant in the area under investigation. However, in practice this assumption is appropriate only in a restricted spatial location, where the local experimental variograms vary slowly. Therefore, an adaptive method is developed in this article to model non-stationary variograms, for which the estimator and the indicator for characterization of spatial variation are a Voronoi map and the standard deviation of mean values displayed in the Voronoi map, respectively. For the adaptive method, the global domain is divided into different meshes with various sizes according to the variability of local variograms. The adaptive method of non-stationary variogram modeling is applied to simulating error surfaces of a LiDAR derived DEM located in Sichuan province, China. Results indicate that the locally adaptive variogram model is more accurate than the global one for capturing the characterization of spatial variation in DEM errors. The adaptive model can be considered as an alternative approach to modeling non-stationary variograms for DEM error surface simulation. Numéro de notice : A2012-619 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1111/j.1467-9671.2012.01326.x En ligne : https://doi.org/10.1111/j.1467-9671.2012.01326.x Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=32065
in Transactions in GIS > vol 16 n° 6 (December 2012) . - pp 885 - 899[article]High-frequency signal and noise estimates of CSR GRACE RL04 / J.A. Bonin in Journal of geodesy, vol 86 n° 12 (December 2012)PermalinkOperational TanDEM-X DEM calibration and first validation results / A. Gruber in ISPRS Journal of photogrammetry and remote sensing, vol 73 (September 2012)PermalinkRelative height error analysis of TanDEM-X elevation data / P. Rizzoli in ISPRS Journal of photogrammetry and remote sensing, vol 73 (September 2012)PermalinkWhat factors lead to software project failure and whose fault was it? / J. Verner in Ingénierie des systèmes d'information, ISI : Revue des sciences et technologies de l'information, RSTI, vol 14 n° 4 (juillet - août 2009)PermalinkRole of tie points in integrated sensor orientation for photogrammetric map compilation / Kourosh Khoshelham in Photogrammetric Engineering & Remote Sensing, PERS, vol 75 n° 3 (March 2009)PermalinkA simulation study of the errors of omission and commission for GRACE RL01 gravity fields / B. Gunter in Journal of geodesy, vol 80 n° 7 (October 2006)PermalinkSeparating surface emissivity and temperature using two-channel spectral indices and emissivity composites and comparison with a vegetation fraction method / P. Dash in Remote sensing of environment, vol 96 n° 1 (15/05/2005)PermalinkMIRAS end-to-end calibration: application to SMOS L1 processor / I. Corbella in IEEE Transactions on geoscience and remote sensing, vol 43 n° 5 (May 2005)PermalinkGeographic Information Systems and science / Paul A. Longley (2005)PermalinkQualité de l'information géographique / Rodolphe Devillers (2005)Permalink