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Auteur Yanxiong Liu |
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Improving GNSS-acoustic positioning by optimizing the ship’s track lines and observation combinations / Guanxu Chen in Journal of geodesy, vol 94 n° 6 (June 2020)
[article]
Titre : Improving GNSS-acoustic positioning by optimizing the ship’s track lines and observation combinations Type de document : Article/Communication Auteurs : Guanxu Chen, Auteur ; Yang Liu, Auteur ; Yanxiong Liu, Auteur ; et al., Auteur Année de publication : 2020 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale
[Termes IGN] contrainte géométrique
[Termes IGN] fond marin
[Termes IGN] GNSS-Acoustique
[Termes IGN] navire
[Termes IGN] positionnement par GNSS
[Termes IGN] précision du positionnement
[Termes IGN] profondeur
[Termes IGN] station GNSS
[Termes IGN] trajectoire (véhicule non spatial)Résumé : (auteur) The position of a seafloor geodetic station can be determined by combining Global Navigation Satellite System (GNSS) and acoustic technologies, called GNSS-acoustic positioning. The precision of GNSS-acoustic positioning, a technique that employs the distance intersection, is determined by the positioning geometry formed by the ship’s track lines with respect to the seafloor station and the errors in the measurements. In the context of a shallow sea trial, we studied three key techniques in GNSS-acoustic positioning: the optimal geometric configuration, differencing techniques for acoustic observations and depth constraints offered by pressure gauges. The results showed that the optimal geometric configuration is a circular track with a radius of 2‾√ times the depth plus an overhead cross-track with a length of the circle diameter. Differenced observations can improve the horizontal positioning precision but will worsen the vertical positioning precision due to the change in the geometric configuration and the elimination of vertical information if the number of observations is limited. The proposed difference strategy, that is, applying a symmetric location difference operator to the circular track and an undifference operator to the cross-track, can effectively improve the horizontal precision and avoid vertical defects. By using relative depth observations from two pressure gauges as constraints, the vertical defects of GNSS-acoustic positioning can be improved, achieving a better vertical positioning precision. Applying the proposed methods to high-quality GNSS and acoustic observations, the positioning precision of a shallow seafloor geodetic station can be better than 2 cm. Numéro de notice : A2020-377 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1007/s00190-020-01389-1 Date de publication en ligne : 27/06/2020 En ligne : https://doi.org/10.1007/s00190-020-01389-1 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=95369
in Journal of geodesy > vol 94 n° 6 (June 2020)[article]Using small baseline Interferometric SAR to map nonlinear ground motion: a case study in Northern Tibet / Zhenhong Li in Journal of applied geodesy, vol 3 n° 3 (August 2009)
[article]
Titre : Using small baseline Interferometric SAR to map nonlinear ground motion: a case study in Northern Tibet Type de document : Article/Communication Auteurs : Zhenhong Li, Auteur ; Yanxiong Liu, Auteur ; et al., Auteur Année de publication : 2009 Article en page(s) : pp 163 - 170 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image radar et applications
[Termes IGN] déformation de la croute terrestre
[Termes IGN] image Envisat-ASAR
[Termes IGN] image radar moirée
[Termes IGN] interféromètrie par radar à antenne synthétique
[Termes IGN] mouvement de terrain
[Termes IGN] TibetRésumé : (auteur) With its global coverage and all-weather imaging capability, Interferometric SAR (InSAR) has been revolutionizing our ability to image the Earth's surface and the evolution of its shape over time. In turn, this has led to many new insights into geophysical and engineering processes, such as volcanoes, earthquakes, landslides and mining activity. In this study, we used an advanced InSAR time series technique to map ground motion of an area in Northern Tibet using ENVISAT images acquired between 2003 and 2007. In order to minimise the effects of baseline decorrelation, a subset of possible pairs having a perpendicular baseline (i.e. orbital separation) of less than 400 m was chosen for the InSAR time series analysis. The time series results reveal an ‘unexpected’ nonlinear ground motion: the area of interest was relatively stable during the period from 2003 to the middle of 2004, whilst it has exhibited a nearly linear uplift of about 8 cm since the middle of 2004. Examination of high-resolution ALOS PRISM images shows that the uplift signal occurred over the Huatugou oil field and is most likely caused by water injection. This study highlights the potential of InSAR as an early detection tool of surface deformations. Numéro de notice : A2009-568 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Article DOI : 10.1515/JAG.2009.017 Date de publication en ligne : 18/08/2009 En ligne : https://doi.org/10.1515/JAG.2009.017 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=75409
in Journal of applied geodesy > vol 3 n° 3 (August 2009) . - pp 163 - 170[article]