Centre de documentation
scientifique

Optimisation of GNSS networks, considering baseline correlations / M. Amin Alizadeh-Khameneh in Survey review, vol 51 n° 364 (January 2019)  

Public [article]  inSurvey review > vol 51 n° 364 (January 2019) . - pp 35 - 42 Titre : Optimisation of GNSS networks, considering baseline correlations Type de document : Article/Communication Auteurs : M. Amin Alizadeh-Khameneh, Auteur ; Lars E. Sjöberg, Auteur ; Anna B. O. Jensen, Auteur Année de publication : 2019 Article en page(s) : pp 35 - 42 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Systèmes de référence et réseaux [Termes IGN] corrélation [Termes IGN] données GNSS [Termes IGN] double différence [Termes IGN] ligne de base [Termes IGN] optimisation (mathématiques) [Termes IGN] réseau géodésique local [Termes IGN] Suède Résumé : (Auteur) By considering global navigation satellite system (GNSS) observations, one can perform optimisation according to some pre-defined criteria and come up with the best location of receivers and optimum number of baselines. In practice, it is quite common to neglect the effect of correlations between baselines, and instead assume single-baseline-adjusted data in the optimisation procedure. However, in each session of observation, usually more than two receivers are simultaneously taking data from a number of common GNSS satellites, implying that the single- or double-difference observations are correlated. Our study designs an optimal observation plan for a GPS network in Skåne in southern Sweden, with the aim of determining possible displacements. Assuming three receivers in each session of observations leads to correlation between the GPS baselines, and consequently a fully populated weight matrix for each session of observation. A bi-objective optimisation model of precision and reliability is chosen to optimise the variance factor of each session, and eventually, design an observation plan. It is shown in this study that observing six out of ten possible sessions is sufficient to enable the network to detect a 5 mm displacement at each station. Assuming that the double-difference phase observations are uncorrelated changes the observation plan by retaining two more sessions. However, defining the weight matrix based on the double-difference observations requires the correlations to be taken into account, and neglecting them leads to incorrect results. Numéro de notice : A2019-187 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Numéro de périodique nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2017.1342896 Date de publication en ligne : 26/06/2017 En ligne : https://doi.org/10.1080/00396265.2017.1342896 Format de la ressource électronique : URL Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=92618 [article]

Optimization of deformation monitoring networks using finite element strain analysis / M. Amin Alizadeh-Khameneh in Journal of applied geodesy, vol 12 n° 2 (April 2018)  

Public [article]  inJournal of applied geodesy > vol 12 n° 2 (April 2018) . - pp Titre : Optimization of deformation monitoring networks using finite element strain analysis Type de document : Article/Communication Auteurs : M. Amin Alizadeh-Khameneh, Auteur ; Mehdi Eshagh, Auteur ; Anna B. O. Jensen, Auteur Année de publication : 2018 Article en page(s) : pp Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes IGN] extensométrie [Termes IGN] faille géologique [Termes IGN] méthode des éléments finis [Termes IGN] réseau de surveillance géophysique [Termes IGN] Suède [Termes IGN] surveillance géologique [Termes IGN] triangulation de Delaunay Résumé : (auteur) An optimal design of a geodetic network can fulfill the requested precision and reliability of the network, and decrease the expenses of its execution by removing unnecessary observations. The role of an optimal design is highlighted in deformation monitoring network due to the repeatability of these networks. The core design problem is how to define precision and reliability criteria. This paper proposes a solution, where the precision criterion is defined based on the precision of deformation parameters, i. e. precision of strain and differential rotations. A strain analysis can be performed to obtain some information about the possible deformation of a deformable object. In this study, we split an area into a number of three-dimensional finite elements with the help of the Delaunay triangulation and performed the strain analysis on each element. According to the obtained precision of deformation parameters in each element, the precision criterion of displacement detection at each network point is then determined. The developed criterion is implemented to optimize the observations from the Global Positioning System (GPS) in Skåne monitoring network in Sweden. The network was established in 1989 and straddled the Tornquist zone, which is one of the most active faults in southern Sweden. The numerical results show that 17 out of all 21 possible GPS baseline observations are sufficient to detect minimum 3 mm displacement at each network point. Numéro de notice : A2018-175 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2017-0040 Date de publication en ligne : 28/03/2018 En ligne : https://doi.org/10.1515/jag-2017-0040 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=89811 [article]