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Pushing the sensitivity limits of RTS-based continuous deformation monitoring of an alpine valley / Mariusz Frukacz in Applied geomatics, vol 9 n° 2 (June 2017)  

Public [article]  inApplied geomatics > vol 9 n° 2 (June 2017) . - pp 81 - 92 Titre : Pushing the sensitivity limits of RTS-based continuous deformation monitoring of an alpine valley Type de document : Article/Communication Auteurs : Mariusz Frukacz, Auteur ; Robert Presl, Auteur ; Andreas Wieser, Auteur ; Daniele Favot, Auteur Année de publication : 2017 Article en page(s) : pp 81 - 92 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] déformation de la croute terrestre [Termes descripteurs IGN] glacier [Termes descripteurs IGN] orientation du capteur [Termes descripteurs IGN] réfraction atmosphérique [Termes descripteurs IGN] Suisse [Termes descripteurs IGN] surveillance géologique [Termes descripteurs IGN] tachéomètre électronique robotisé Résumé : (auteur) Monitoring applications may require operating robotic total stations (RTS) at the limit of their sensitivity with respect to target displacements. Thorough understanding and mitigation of systematic effects are required in order to reach or push this limit. We investigate some of these effects, in particular effects external to the total station, using data and experience gained from a continuously operating monitoring system installed at the terminus of the Great Aletsch Glacier in Switzerland. The system consists of two robotic total stations, about 60 prisms, four global navigation satellite system (GNSS) receivers, thermocouples, inclinometers, and meteo-sensors. The purpose of the monitoring is to study reversible deformations of the adjacent slopes, likely driven by snowmelt and mountain water level changes. The deformations reach the millimeter- to centimeter-level and shall be studied on time scales ranging from annual to sub-annual, and ideally even down to daily or sub-daily resolution. Our investigation focuses on four aspects: protective housing, pillar stability, refraction, and stability of orientation, all of which were found to affect the measurements on the milligon-level with lines-of-sight of up to 2 km. The results highlight signatures of apparent point displacements, and the discussion comprises approaches to bounding or mitigating these effects which may also be expected in similar monitoring situations at other locations. Numéro de notice : A2017-359 Thématique : POSITIONNEMENT Nature : Article En ligne : http://doi.org/10.1007/s12518-017-0182-2 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85768 [article]

The variability of water vapour and pre-convective conditions over the mountainous island of Corsica / Bianca Adler in Quarterly Journal of the Royal Meteorological Society, vol 142 n° S1 (August 2016)  

Public [article]  inQuarterly Journal of the Royal Meteorological Society > vol 142 n° S1 (August 2016) . - pp 335 - 346 Titre : The variability of water vapour and pre-convective conditions over the mountainous island of Corsica Type de document : Article/Communication Auteurs : Bianca Adler, Auteur ; Norbert Kalthoff, Auteur ; Martin Kohler, Auteur ; Jan Handwerker, Auteur ; Andreas Wieser, Auteur ; Ulrich Corsmeier, Auteur ; Christoph Kottmeier, Auteur ; Dominique Lambert, Auteur ; Olivier Bock , Auteur Année de publication : 2016 Projets : HyMeX / Article en page(s) : pp 335 - 346 Note générale : biblographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de géodésie spatiale [Termes descripteurs IGN] circulation atmosphérique [Termes descripteurs IGN] convection [Termes descripteurs IGN] coordonnées GPS [Termes descripteurs IGN] Corse [Termes descripteurs IGN] couche atmosphérique [Termes descripteurs IGN] données météorologiques [Termes descripteurs IGN] teneur intégré en vapeur d'eau Résumé : (auteur) Comprehensive measurements were carried out on the mountainous island of Corsica during the Hydrological cycle in the Mediterranean Experiment (HyMeX) field campaign in 2012. Using data from an operational GPS network, radiosondes and microwave radiometers, we studied the spatio-temporal variability of integrated water vapour (IWV) and convection-related parameters in the pre-convective environment over the island. The following spatial differences in the IWV evolution occurred frequently. In the interior of the island the IWV strongly increased around noon, while on the upstream coast only small variations were observed. We showed that a transport of water vapour with thermally driven circulations and the formation of elevated humidity layers due to advective venting caused the diurnal IWV variation over and downstream of the mountains. Spatial inhomogeneities in the pre-convective atmospheric conditions evolved and the knowledge of these turned out to be crucial to understanding the timing and location of isolated deep convection over the island. Numéro de notice : A2016-937 Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1002/qj.2545 date de publication en ligne : 04/03/2015 En ligne : http://dx.doi.org/10.1002/qj.2545 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=83290 [article]

On weighted total least-squares adjustment for linear regression / Burkhard Schaffrin in Journal of geodesy, vol 82 n° 7 (July 2008)

Public [article]  inJournal of geodesy > vol 82 n° 7 (July 2008) . - pp 415 - 421 Titre : On weighted total least-squares adjustment for linear regression Type de document : Article/Communication Auteurs : Burkhard Schaffrin, Auteur ; Andreas Wieser, Auteur Année de publication : 2008 Article en page(s) : pp 415 - 421 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Statistiques [Termes descripteurs IGN] compensation par moindres carrés [Termes descripteurs IGN] pondération [Termes descripteurs IGN] régression linéaire [Termes descripteurs IGN] régression multiple Résumé : (Auteur) The weighted total least-squares solution (WTLSS) is presented for an errors-in-variables model with fairly general variance–covariance matrices. In particular, the observations can be heteroscedastic and correlated, but the variance–covariance matrix of the dependent variables needs to have a certain block structure. An algorithm for the computation of the WTLSS is presented and applied to a straight-line fit problem where the data have been observed with different precision, and to a multiple regression problem from recently published climate change research. Copyright Springer Numéro de notice : A2008-318 Thématique : MATHEMATIQUE Nature : Article nature-HAL : ArtAvecCL-RevueIntern Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29311 [article]

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A GNSS odometer: how far have we come? / Andreas Wieser in GPS world, vol 19 n° 4 (April 2008)

Public [article]  inGPS world > vol 19 n° 4 (April 2008) . - pp 50 - 55 Titre : A GNSS odometer: how far have we come? Type de document : Article/Communication Auteurs : Andreas Wieser, Auteur Année de publication : 2008 Article en page(s) : pp 50 - 55 Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement [Termes descripteurs IGN] écart type [Termes descripteurs IGN] erreur systématique [Termes descripteurs IGN] géonavigateur [Termes descripteurs IGN] GPS assisté pour la navigation (technologies) [Termes descripteurs IGN] Matlab [Termes descripteurs IGN] odomètre [Termes descripteurs IGN] positionnement par GNSS [Termes descripteurs IGN] précision des mesures Résumé : (Editeur) [...] The odometer was likely first invented by Archimides during the First Punic War when Syracuse got in the way of Rome during its battle with Carthage. A Greek origin is fitting as the word odometer derives from the Greek words hodos, meaning "path" or "way" and matron, meaning "measure," The device was reinvented many times over the years but its use was not widespread until the development of the automobile, and now virtually every vehicle sports one. Mechanical odometers gave way to electronic ones but the distance travelled was and is still determined by counting wheel revolutions. But just how accurate are the odometers in our modern vehicles? Not very, it seems. The odometer reading is affected by tire pressure, tire slip, and incorrect calibration. And while in many countries there is no regulation covering odometer accuracy, the Society of Automotive Engineers' voluntary standard and that of the European Commission is only plus or minus 4 percent, or as much as a 4-kilometer error in every 100 km. Does this matter? Well, in effort to reduce the cost to the general tax payer of maintaining roads or reducing congestion, many administrations have implemented "road pricing," where a flat charge is levied for using a particular stretch of road or for entering a city center. But some administrations are charging per kilometer of travel with data coming from an odometer recording. Automobile insurance companies have also implemented plans where the premium is based on the distance travelled by the vehicle ("pay as you drive"). To fairly implement such schemes, governments should require more accurate odometers in vehicles. Could an odometer based on GNSS be a solution? In this month's column, we take a look at how distance travelled can be computed from GNSS observations and just how accurate those computations are. Copyright Questex Media Group Inc Numéro de notice : A2008-163 Thématique : POSITIONNEMENT Nature : Article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=29158 [article]

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