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GPS + Galileo + QZSS + BDS tightly combined single-epoch single-frequency RTK positioning / Shaolin Zhu in Survey review, vol 53 n°376 (January 2021)
[article]
Titre : GPS + Galileo + QZSS + BDS tightly combined single-epoch single-frequency RTK positioning Type de document : Article/Communication Auteurs : Shaolin Zhu, Auteur ; Dongjie Yue, Auteur ; Jian Chen, Auteur ; et al., Auteur Année de publication : 2021 Article en page(s) : pp 16 - 26 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] données BeiDou
[Termes IGN] données Galileo
[Termes IGN] données GPS
[Termes IGN] modèle stochastique
[Termes IGN] positionnement cinématique en temps réel
[Termes IGN] positionnement par GNSS
[Termes IGN] précision du positionnement
[Termes IGN] qualité du signal
[Termes IGN] Quasi-Zenith Satellite System
[Termes IGN] récepteur monofréquence
[Termes IGN] résolution d'ambiguïtéRésumé : (auteur) The multi-GNSS fusion makes positioning more reliable and accurate. Considering the signal difference of different systems, GPS + Galileo + QZSS + BDS tightly combined double-difference model (TCDDM), including function and stochastic model, is proposed. The proposed model fully utilizes the overlapping frequency signals of various systems, and thus to enhance positioning model when DISBs are known beforehand. The observations of 3 ultra-short (1~10 m) and 3 short (4~10 km) baselines were processed by self-programming software, and the single-epoch single-frequency RTK performance using different system-combined models was evaluated by ambiguity-fixed correctness rate (ACR) and positioning accuracy. It demonstrated that three- and four-system TCDDM were superior to their corresponding loosely combined double-difference model (LCDDM) for ACR and positioning accuracy especially at high cut-off elevation. Moreover, four-system TCDDM had the best RTK performance obtaining average ACRs of 100% and 97.6% even at 25° cut-off elevation for ultra-short and short baseline, respectively. Numéro de notice : A2021-047 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article nature-HAL : ArtAvecCL-RevueIntern DOI : 10.1080/00396265.2019.1681681 Date de publication en ligne : 13/11/2019 En ligne : https://doi.org/10.1080/00396265.2019.1681681 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96782
in Survey review > vol 53 n°376 (January 2021) . - pp 16 - 26[article]High accuracy terrestrial positioning based on time delay and carrier phase using wideband radio signals / Han Dun (2021)
Titre : High accuracy terrestrial positioning based on time delay and carrier phase using wideband radio signals Type de document : Thèse/HDR Auteurs : Han Dun, Auteur Editeur : Delft [Pays-Bas] : Delft University of Technology Année de publication : 2021 Format : 21 x 30 cm ISBN/ISSN/EAN : 978-94-6384-258-7 Note générale : bibliographie
Thèse présentée en vue de l'obtention du Doctorat de l'Université de DelftLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement du signal
[Termes IGN] centre de phase
[Termes IGN] correction du trajet multiple
[Termes IGN] interruption du signal
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] phase
[Termes IGN] précision du positionnement
[Termes IGN] signal GNSS
[Termes IGN] zone urbaineIndex. décimale : THESE Thèses et HDR Résumé : (auteur) Accurate position solutions are in high demand for many emerging applications. Global navigation satellite systems (GNSS), however, may not meet the required positioning performance, especially in urban environments, due to multipath and weak received power of the GNSS signal that can be easily blocked by surrounding objects. To achieve a high ranging precision and improve resolvability of unwanted reflections in urban areas, a large signal bandwidth is required. In this thesis, a terrestrial positioning system using a wideband radio signal is developed as a complement to the existing GNSS, which can provide a better ranging accuracy and higher received signal power, compared to GNSS. In the terrestrial positioning system presented in this thesis, a wideband ranging signal is implemented by means of a multiband orthogonal frequency division multiplexing (OFDM) signal. All transmitters are synchronized by time and frequency reference signals, which are optically distributed through the white-rabbit precision time protocol (WR-PTP). Like in GNSS, the to-be-positioned receiver is not synchronized to the transmitters. Positioning takes place through range measurements between a number of transmitters and the receiver. Time delay and carrier phase are to be estimated from the received radio signal, which propagated through a multipath channel. This estimation is done on the basis of the channel frequency response and using the maximum likelihood principle. To determine whether or not reflections need to be considered in the estimation model, a measure of dependence is introduced to evaluate the change of the precision (i.e., variance), and the measure of bias is introduced to assess the bias of the estimator when the reflection is not considered. Also, a methodology is proposed for sparsity-promoting ranging signal design in this thesis. Based on a multiband OFDM signal, ranging signal design comes to sparsely select as few signal bands as possible. Using fewer signal bands for ranging leads to less computational complexity in time delay and carrier phase estimation, while the ranging performance can still benefit from a large virtual signal bandwidth, which is defined by the entire bandwidth between the two signal bands at the spectral edges. It is proposed to use the Cramér-Rao lower bound (CRLB) of time delay estimation, the measure of dependence, and the measure of bias as constraints in ranging performance, and formulate an optimization problem to design a sparse multiband signal. Note de contenu : 1- Introduction
2- Multiband OFDM signal model
3- Time delay estimation
4- Carrier phase estimation
5- Signal design for positioning
6- Positioning models
7- Experimental results
8- Conclusions and recommendationsNuméro de notice : 28694 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : Thèse de Doctorat : Mathematical Geodesy and Positioning : Delft : 2021 DOI : 10.4233/uuid:98a7f072-7423-4a23-ac9b-8b88540c260d En ligne : https://doi.org/10.4233/uuid:98a7f072-7423-4a23-ac9b-8b88540c260d Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100361 Model based signal processing techniques for nonconventional optical imaging systems / Daniele Picone (2021)
Titre : Model based signal processing techniques for nonconventional optical imaging systems Type de document : Thèse/HDR Auteurs : Daniele Picone, Auteur ; Mauro Dalla Mura, Directeur de thèse Editeur : Grenoble [France] : Université Grenoble Alpes Année de publication : 2021 Importance : 364 p. Format : 21 x 30 cm Note générale : bibliographie
Thèse pour obtenir le grade de Docteur de l'Université Grenoble Alpes, spécialité : Signal Image Parole TélécomsLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] acquisition comprimée
[Termes IGN] fusion d'images
[Termes IGN] image hyperspectrale
[Termes IGN] inférence statistique
[Termes IGN] interférométrie
[Termes IGN] méthode du maximum de vraisemblance (estimation)
[Termes IGN] mosaïque d'images
[Termes IGN] pouvoir de résolution géométrique
[Termes IGN] pouvoir de résolution spectrale
[Termes IGN] problème inverse
[Termes IGN] reconstruction d'image
[Termes IGN] régression non linéaire
[Termes IGN] spectromètre imageur
[Termes IGN] traitement du signalIndex. décimale : THESE Thèses et HDR Résumé : (auteur) There is an increasing demand for images with higher spectral and spatial resolution for applications in several domains such as health, environment, quality checking and natural disasters monitoring. Hyperspectral imagery provides the necessary spectral diversity to recover the composition of materials on site for applications such as the detection of fires, anomalies, chemical agents, targets and changes in the scene.The requirement for cheaper and more compact devices (e.g. to be embarked on low cost satellites and airborne platform) which are capable of capturing this information has led to the development of nonconventional innovative design concepts to overcome the technological limitations of traditional cameras. Data acquired by such novel imaging devices following the computational imaging paradigm are typically not readily exploitable for the final application. A computational phase is hence needed for extracting useful information from the raw acquisitions.This thesis addresses this issue by setting up an inversion problem. The general approach is to characterize the data fidelity term with a physical model, describing the underlying optical transformations performed by the device. The challenge is then shifted on the regularization step to properly characterizes the features of the quantities of interest and improve the accuracy of the estimation, which can be tackled with variational techniques.The analysis is applied to two novel concepts for nonconventional optical devices. The first one is a novel compressed acquisition imaging system based on color filter arrays, which embeds information from sensors with different spatial and spectral characteristics into a single mosaiced product. As opposed to existing compressed sensing based devices, the goal is not to recover the original uncompressed multiresolution sources, but instead to directly recover a synthetic fused image with both high spatial and spectral resolution.The proposed solution relies on the total variation regularization and is the subject of a detailed analysis, comparing its compressive power with straightforward software alternatives, evaluating its performances as the amount of channels changes, and validating its efficiency in comparison to state of the art methods when applied to classical fusion or mosaicing algorithms separately.The second class of devices is based on the ImSPOC patent, a design concept for a low finesse snapshot imaging spectrometer based on the interferometry of Fabry-Pérot. Its ideal behaviour follows the principle of the Fourier Transform Spectroscopy, as its acquisition can be interpreted as a sampled version of an interferogram, arranged across different sub-images distributed on the same focal plane.After defining a physical model based on optical geometry, its validity is evaluated over real acquisitions by setting up a Bayesian inference problem to determine its parameters, with approaches based on maximum likelihood estimators, regular-grid searches and nonlinear regression.A variety of preliminary tests are then carried out on the inversion method, with approaches based on singular value decomposition and sparse-inducing regularizers, accompanied by a analysis of their robustness to model mismatches. Note de contenu : 1- Introduction
2- Inverse problems theory
3- Signal processing of multimodal data
4- Joint fusion and demosaicing of compressed multiresolution acquisitions
5- Optics foundations for the ImSPOC acquisition system
6- Data processing pipeline of ImSPOC acquisitions
7- ConclusionsNuméro de notice : 28691 Affiliation des auteurs : non IGN Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Signal Image Parole Télécoms : Grenoble : 2021 Organisme de stage : GIPSA-lab DOI : sans En ligne : https://hal.science/tel-03596486v1 Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=100170
Titre : Predicting future urban drought under climate change Titre original : Prédire les sécheresses urbaines dans le contexte du changement climatique Type de document : Thèse/HDR Auteurs : Changsen Zhao, Auteur ; Françoise Nerry, Directeur de thèse ; Zhao-Liang Li, Directeur de thèse Editeur : Strasbourg : Université de Strasbourg Année de publication : 2021 Importance : 145 p. Format : 21 x 30 cm Note générale : Bibliographie, résumé long en français
Thèse présentée pour obtenir le grade de Docteur de l'Université de Strasbourg, Discipline Sciences de l'Imagerie, Spécialité TélédétectionLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Applications de télédétection
[Termes IGN] changement climatique
[Termes IGN] Chine
[Termes IGN] données GLDAS
[Termes IGN] données GRACE
[Termes IGN] eau de surface
[Termes IGN] eau souterraine
[Termes IGN] estimation statistique
[Termes IGN] fusion de données multisource
[Termes IGN] image captée par drone
[Termes IGN] image satellite
[Termes IGN] milieu urbain
[Termes IGN] réseau neuronal artificiel
[Termes IGN] sécheresse
[Termes IGN] série temporelleIndex. décimale : THESE Thèses et HDR Résumé : (Auteur) De nombreuses villes du monde manquent de données et ne peuvent donc pas prévoir avec précision les sécheresses urbaines futures (UD) dans le contexte des changements climatiques. Par conséquent, cette thèse a mis en avant un nouveau cadre pour prédire l’UD future. En couplant des images de satellites et de drones, nous avons présenté deux ensembles de nouvelles méthodes pour l’estimation des eaux de surface disponibles ; en couplant les données issues du satellite GRACE de la NASA et l’ensemble de données GLDAS, nous avons proposé une nouvelle méthode de prévision des eaux souterraines disponibles. Toutes les méthodes ont été vérifiées en utilisant des observations au sol et des données fournies par GRACE dans trois grandes villes du bassin du fleuve Jaune, en Chine. Avec ces méthodes, nous avons reconstitué des séries de données sur les eaux de surface et souterraines disponibles pour les trois villes au cours de la période 1948-2001, lorsque les données disponibles sur l’eau sont manquantes. Avec ces données reconstituées sur la disponibilité de l’eau et les projections de consommation d’eau, nous avons prédit l’UD de trois grandes villes en Chine en 2030 et 2050 en exploitant un réseau neuronal artificiel sur la base de scénarios climatiques CMIP5. Les résultats montrent que l'UD sera plus sévère en 2030 qu'en 2050. Note de contenu : Chapter 1 - Introduction
1.1 Background
1.2 Objectives
1.3 State of the art of drought assessment and prediction
1.4 Large-scaled drought assessment with multi-source data inclusive of satellite imageries
1.5 Assessment of water consumption
1.6 Flow chart and outline of the dissertation research
Chapter 2 - Data and study area
2.1 Data collection and verification
2.2 Characteristics of study area
Chapter 3 - Estimation of surface freshwater available
3.1 Retrieval of long-termed streamflow for the three representative cities
3.2 Surface freshwater available (FWA) for the three representative cities
3.3 Summary
Chapter 4 - Estimation of underground freshwater available
4.1 Determining factors driving the variation of underground FWA (vertical water flux)
4.2 Extension of data series of underground FWA
4.3 Summary
Chapter 5 - Calculation of water consumption
5.1 Estimation of water quantity sustaining household
5.2 Estimation of water quantity for industry
5.3 Estimation of water quantity consumed by ecosystems
5.4 Estimation of total water consumption
5.5 Summary
Chapter 6 - Prediction of urban drought in 2030 and 2050
6.1 Prediction of freshwater available
6.2 Prediction of water consumption
6.3 Future urban drought in the year 2030 and 2050
6.4 Summary
Chapter 7 - Conclusions and perspectives
7.1 Main conclusions
7.2 PerspectivesNuméro de notice : 26945 Affiliation des auteurs : non IGN Autre URL associée : vers HAL Thématique : IMAGERIE Nature : Thèse française Note de thèse : Thèse de Doctorat : Discipline Sciences de l'Imagerie, Spécialité Télédétection : Strasbourg : 2021 Organisme de stage : ICube, Laboratoire des sciences de l'ingénieur, de l'informatique et de l'imagerie nature-HAL : Thèse DOI : sans Date de publication en ligne : 12/09/2022 En ligne : https://publication-theses.unistra.fr/public/theses_doctorat/2021/Zhao_Changsen_ [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=102146 Probabilistic positioning in mobile phone network and its consequences for the privacy of mobility data / Aleksey Ogulenko in Computers, Environment and Urban Systems, vol 85 (January 2021)
[article]
Titre : Probabilistic positioning in mobile phone network and its consequences for the privacy of mobility data Type de document : Article/Communication Auteurs : Aleksey Ogulenko, Auteur ; Itzhak Benenson, Auteur ; Itzhak Omer, Auteur Année de publication : 2021 Article en page(s) : n° 101550 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Analyse spatiale
[Termes IGN] antenne
[Termes IGN] classification bayesienne
[Termes IGN] confidentialité
[Termes IGN] diagramme de Voronoï
[Termes IGN] estimation bayesienne
[Termes IGN] géolocalisation
[Termes IGN] inférence
[Termes IGN] protection de la vie privée
[Termes IGN] réseau téléphonique
[Termes IGN] téléphonie mobile
[Termes IGN] tessellationRésumé : (auteur) The traditional approach to mobile phone positioning is based on the assumption that the geographical location of a cell tower recorded in a Call Details Record (CDR) is a proxy for a device's location. A Voronoi tessellation is then constructed based on the entire network of cell towers and this tessellation is considered as a coordinate system, with the device located in a Voronoi polygon of a cell tower that is recorded in the CDR. If Voronoi-based positioning is correct, the uniqueness of the device trajectory is very high, and the device can be identified based on 3–5 of its recorded locations. We investigate a probabilistic approach to device positioning that is based on knowledge of each antennas' parameters and number of connections, as dependent on the distance to the antenna. The critical difference between the Voronoi-based and the real world layout is in the essential overlap of the antennas' service areas: The device that is located in a cell tower's polygon can be served by a more distant antenna that is chosen by the network system to balance the network load. Combining data on the distance distribution of the number of connections available for each antenna in the network, we resolve the overlap problem by applying Bayesian inference and construct a realistic distribution of the device location. Probabilistic device positioning demands a full revision of mobile phone privacy and new full set of tools for data analysis. Numéro de notice : A2021-005 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE/MATHEMATIQUE Nature : Article DOI : 10.1016/j.compenvurbsys.2020.101550 Date de publication en ligne : 14/10/2020 En ligne : https://doi.org/10.1016/j.compenvurbsys.2020.101550 Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=96272
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