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Comparison of precise orbit determination methods of zero-difference kinematic, dynamic and reduced-dynamic of GRACE-A satellite using SHORDE software / Kai Li in Journal of applied geodesy, vol 11 n° 3 (September 2017)
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Titre : Comparison of precise orbit determination methods of zero-difference kinematic, dynamic and reduced-dynamic of GRACE-A satellite using SHORDE software Type de document : Article/Communication Auteurs : Kai Li, Auteur ; Xuhua Zhou, Auteur ; Nannan Guo, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 157 - 166 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Technologies spatiales
[Termes IGN] coordonnées GPS
[Termes IGN] GRACE
[Termes IGN] mesurage de phase
[Termes IGN] orbite basse
[Termes IGN] orbitographieRésumé : (Auteur) Zero-difference kinematic, dynamic and reduced-dynamic precise orbit determination (POD) are three methods to obtain the precise orbits of Low Earth Orbit satellites (LEOs) by using the on-board GPS observations. Comparing the differences between those methods have great significance to establish the mathematical model and is usefull for us to select a suitable method to determine the orbit of the satellite. Based on the zero-difference GPS carrier-phase measurements, Shanghai Astronomical Observatory (SHAO) has improved the early version of SHORDE and then developed it as an integrated software system, which can perform the POD of LEOs by using the above three methods. In order to introduce the function of the software, we take the Gravity Recovery And Climate Experiment (GRACE) on-board GPS observations in January 2008 as example, then we compute the corresponding orbits of GRACE by using the SHORDE software. In order to evaluate the accuracy, we compare the orbits with the precise orbits provided by Jet Propulsion Laboratory (JPL). The results show that: (1) If we use the dynamic POD method, and the force models are used to represent the non-conservative forces, the average accuracy of the GRACE orbit is 2.40cm, 3.91cm, 2.34cm and 5.17cm in radial (R), along-track (T), cross-track (N) and 3D directions respectively; If we use the accelerometer observation instead of non-conservative perturbation model, the average accuracy of the orbit is 1.82cm, 2.51cm, 3.48cm and 4.68cm in R, T, N and 3D directions respectively. The result shows that if we use accelerometer observation instead of the non-conservative perturbation model, the accuracy of orbit is better. (2) When we use the reduced-dynamic POD method to get the orbits, the average accuracy of the orbit is 0.80cm, 1.36cm, 2.38cm and 2.87cm in R, T, N and 3D directions respectively. This method is carried out by setting up the pseudo-stochastic pulses to absorb the errors of atmospheric drag and other perturbations. (3) If we use the kinematic POD method, the accuracy of the GRACE orbit is 2.92cm, 2.48cm, 2.76cm and 4.75cm in R, T, N and 3D directions respectively. In conclusion, it can be seen that the POD of GRACE satellite is practicable by using different strategies and methods. The orbit solution is well and stable, they all can obtain the GRACE orbits with centimeter-level precision. Numéro de notice : A2017-570 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : 10.1515/jag-2017-0004 En ligne : https://doi.org/10.1515/jag-2017-0004 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86690
in Journal of applied geodesy > vol 11 n° 3 (September 2017) . - pp 157 - 166[article]Consumer mass market accelerometers for GNSS anti-spoofing / Sherman Lo in Inside GNSS, vol 12 n° 5 (September - October 2017)
[article]
Titre : Consumer mass market accelerometers for GNSS anti-spoofing Type de document : Article/Communication Auteurs : Sherman Lo, Auteur ; Yu-Hsuan Chen, Auteur ; Tyler Reid, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 62 - 71 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Navigation et positionnement
[Termes IGN] accéléromètre
[Termes IGN] anti-leurrage
[Termes IGN] centrale inertielle
[Termes IGN] couplage GNSS-INS
[Termes IGN] détection de leurrageRésumé : (auteur) This article presents a novel GNSS spoofing detection method via direct comparison of acceleration using commercial inertial sensors. The developed concept allows for comparison of the two sensors without coupling GNSS with an inertial measurement unit (IMU). The design provides a robust, steady state spoof detection capability that can be developed as an add-on to existing receivers. Collected flight test data is used to show that executive monitors (EMs) successfully yielded spoof detection capabilities as well as the ability to limit false alerts. While many more flights will be needed to validate performance results, fast detection ( Numéro de notice : A2017-587 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Article DOI : sans En ligne : http://www.insidegnss.com/node/5619 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86719
in Inside GNSS > vol 12 n° 5 (September - October 2017) . - pp 62 - 71[article]Crowdsourcing a cyclist perspective on suggested recreational paths in real-world networks / Kevin Baker in Cartography and Geographic Information Science, Vol 44 n° 5 (September 2017)
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Titre : Crowdsourcing a cyclist perspective on suggested recreational paths in real-world networks Type de document : Article/Communication Auteurs : Kevin Baker, Auteur ; Kristien Ooms, Auteur ; Steven Verstockt, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 422 - 435 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géomatique web
[Termes IGN] carte thématique
[Termes IGN] chemin le plus court, algorithme du
[Termes IGN] cycliste
[Termes IGN] données localisées des bénévoles
[Termes IGN] géomatique web
[Termes IGN] itinéraire
[Termes IGN] loisir
[Termes IGN] production participative
[Termes IGN] trace GPSRésumé : (Auteur) Routing and navigation services for leisure activities are conditioned by special needs and trade-offs. The advent of online communities and large crowdsourced datasets offers opportunities to improve the adoption of a user’s perspective in these suggested paths. This paper focuses on achieving two goals. First, the presented methodology analyses a dataset of 190,610 historical GPS traces to gain insights into the appreciation or attractiveness of each edge in a real-world network for a specific leisure activity (i.e. road cycling). Second, as literature on these leisure activities is still sparse, we want to create a thorough understanding of the activities at hand for future work. An appreciation model is proposed and the spread of this score is analyzed in shortest-path alternatives of popular routing engines for this activity. This analysis successfully discriminates these shortest paths based on the scoring value and three morphological parameters of the path. However, the robustness of the model should be improved to ensure the viability of the proposed approach in future work. More specifically, further research on the local optimality of the route choices will be imperative. Numéro de notice : A2017-449 Affiliation des auteurs : non IGN Thématique : GEOMATIQUE Nature : Article DOI : 10.1080/15230406.2016.1192486 En ligne : http://dx.doi.org/10.1080/15230406.2016.1192486 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86359
in Cartography and Geographic Information Science > Vol 44 n° 5 (September 2017) . - pp 422 - 435[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 032-2017051 RAB Revue Centre de documentation En réserve L003 Disponible Crown bulk density and fuel moisture dynamics in Pinus pinaster stands are neither modified by thinning nor captured by the Forest Fire Weather Index / Marc Soler Martin in Annals of Forest Science, vol 74 n° 3 (September 2017)
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Titre : Crown bulk density and fuel moisture dynamics in Pinus pinaster stands are neither modified by thinning nor captured by the Forest Fire Weather Index Type de document : Article/Communication Auteurs : Marc Soler Martin, Auteur ; José Antonio Bonet, Auteur ; Juan Martínez De Aragón, Auteur ; et al., Auteur Année de publication : 2017 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] biomasse (combustible)
[Termes IGN] éclaircie (sylviculture)
[Termes IGN] Espagne
[Termes IGN] forêt méditerranéenne
[Termes IGN] houppier
[Termes IGN] incendie de forêt
[Termes IGN] indice d'humidité
[Termes IGN] Pinus pinaster
[Termes IGN] risque naturel
[Termes IGN] surveillance forestière
[Termes IGN] traitement d'image
[Termes IGN] variation saisonnière
[Vedettes matières IGN] Ecologie forestièreRésumé : (Auteur)
Key message : No temporal change was recorded during summer in fuel availability in Pinus pinaster stands, contrary to predictions from the Forest Fire Weather Index. Also, thinning had no mid-term effect on fuel moisture or canopy structure.
Context : Forest fires are a major problem in Mediterranean countries. Management actions, such as fuel reductions, are one of the main tools to diminish fire risk, but the midterm efficacy of such tools remains largely untested with empirical data.
Aims : Here, we test for midterm effects of thinning on fuel moisture and crown bulk density in P. pinaster stands and whether temporal variations in fuel moisture correlated with predictions from the Fire Weather Index, a commonly used index on fire risk, and its components.
Methods : We compared fuel moisture over a fire season and crown bulk density in nine pairs of thinned/unthinned plots 7 years after treatments were applied.
Results : We observed that fuel moisture remained stable during a fire season, as a likely result of drought-induced physiological adjustments, including stomatal regulation and others, which allow leaves to maintain a large humidity even during drought, and that thinning had no midterm effect on fuel moisture or crown bulk density. Moreover, the Fire Weather Index and its components displayed different temporal dynamics than those observed in fuel moisture.
Conclusion : These results are important as they indicate that thinning may only have a limited, short-term impact towards diminishing the potential for crown fire spread in these stands and that current indices to evaluate fire risk may require a re-evaluation.Numéro de notice : A2017-354 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1007/s13595-017-0650-1 Date de publication en ligne : 28/06/2017 En ligne : http://doi.org/10.1007/s13595-017-0650-1 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=85720
in Annals of Forest Science > vol 74 n° 3 (September 2017)[article]Denoising of natural images through robust wavelet thresholding and genetic programming / Asem Khmag in The Visual Computer, vol 33 n°9 (September 2017)
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Titre : Denoising of natural images through robust wavelet thresholding and genetic programming Type de document : Article/Communication Auteurs : Asem Khmag, Auteur ; Abd Rahman Ramli, Auteur ; S.A.R. Al-haddad, Auteur ; et al., Auteur Année de publication : 2017 Article en page(s) : pp 1141 - 1154 Note générale : bibliographie Langues : Anglais (eng) Descripteur : [Vedettes matières IGN] Traitement d'image optique
[Termes IGN] algorithme génétique
[Termes IGN] bruit blanc
[Termes IGN] filtrage du bruit
[Termes IGN] ondelette
[Termes IGN] seuillage d'imageRésumé : (auteur) Digital images play an essential role in analysis tasks that can be applied in various knowledge domains, including medicine, meteorology, geology, and biology. Such images can be degraded by noise during the process of acquisition, transmission, storage, or compression. The use of local filters in image restoration may generate artifacts when these filters are not well adapted to the image content as a result of the heuristic optimization of local filters. Denoising methods based on learning procedure are more capable than parametric filters for addressing the conflicts between noise suppression and artifact reduction. In this study, we present a nonlinear filtering method based on a two-step switching scheme to remove both salt-and-pepper and additive white Gaussian noises. In the switching scheme, two cascaded detectors are used to detect noise, and two corresponding estimators are employed to effectively and efficiently filter the noise in an image. In the process of training, a method according to patch clustering is utilized, and genetic programming (GP) is subsequently applied to determine the optimum filter (wavelet-domain filter) for each individual cluster, while in testing part, the optimum filter trained beforehand by GP is recovered and used on the inputted corrupted patch. This adaptive structure is employed to cope with several noise types. Experimental and comparative analysis results show that the denoising performance of the proposed method is superior to that of existing denoising methods as per both quantitative and qualitative assessments. Numéro de notice : A2017-407 Affiliation des auteurs : non IGN Thématique : IMAGERIE/INFORMATIQUE Nature : Article DOI : 10.1007/s00371-016-1273-5 En ligne : https://doi.org/10.1007/s00371-016-1273-5 Format de la ressource électronique : URL article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=86288
in The Visual Computer > vol 33 n°9 (September 2017) . - pp 1141 - 1154[article]Facet segmentation-based line segment extraction for large-scale point clouds / Yangbin Lin in IEEE Transactions on geoscience and remote sensing, vol 55 n° 9 (September 2017)PermalinkImproving BeiDou real-time precise point positioning with numerical weather models / Cuixian Lu in Journal of geodesy, vol 91 n° 9 (September 2017)PermalinkA mangrove forest map of China in 2015: Analysis of time series Landsat 7/8 and Sentinel-1A imagery in Google Earth Engine cloud computing platform / Bangqian Chen in ISPRS Journal of photogrammetry and remote sensing, vol 131 (September 2017)PermalinkOptimization of simulation and visualization analysis of dam-failure flood disaster for diverse computing systems / Mingwei Liu in International journal of geographical information science IJGIS, vol 31 n° 9-10 (September - October 2017)PermalinkPrecision estimation of the angular resolution of terrestrial laser scanners / Xijiang Chen in Photogrammetric record, vol 32 n° 159 (September 2017)PermalinkReconstruction of time-varying tidal flat topography using optical remote sensing imageries / Kuo-Hsin Tseng in ISPRS Journal of photogrammetry and remote sensing, vol 131 (September 2017)PermalinkSpatiotemporal analyses of urban vegetation structural attributes using multitemporal Landsat TM data and field measurements / Zhibin Ren in Annals of Forest Science, vol 74 n° 3 (September 2017)PermalinkTectonic and anthropogenic deformation at the Cerro Prieto geothermal step-over revealed by sentinel-1A InSAR / Xiaohua Xu in IEEE Transactions on geoscience and remote sensing, vol 55 n° 9 (September 2017)PermalinkTemplate-based GIS computation : a geometric algebra approach / Wen Luo in International journal of geographical information science IJGIS, vol 31 n° 9-10 (September - October 2017)PermalinkUnsupervised domain adaptation for early detection of drought stress in hyperspectral images / P. Schmitter in ISPRS Journal of photogrammetry and remote sensing, vol 131 (September 2017)Permalink