Descripteur
Documents disponibles dans cette catégorie (460)
Ajouter le résultat dans votre panier
Visionner les documents numériques
Affiner la recherche Interroger des sources externes
Etendre la recherche sur niveau(x) vers le bas
Potential productivity of forested areas based on a biophysical model. A case study of a mountainous region in northern Spain / Raquel Benavides in Annals of Forest Science, Vol 66 n° 1 (January - February 2009)
[article]
Titre : Potential productivity of forested areas based on a biophysical model. A case study of a mountainous region in northern Spain Titre original : Productivité potentielle des forêts à partir d'un modèle biophysique. Étude du cas d'une région montagneuse dans le nord de l'Espagne Type de document : Article/Communication Auteurs : Raquel Benavides, Auteur ; Sonia Roig, Auteur ; Koldo Osoro, Auteur Année de publication : 2009 Article en page(s) : n° 108 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] Espagne
[Termes IGN] forêt alpestre
[Termes IGN] géostatistique
[Termes IGN] modèle mathématique
[Termes IGN] système d'information géographique
[Termes IGN] utilisation du sol
[Vedettes matières IGN] SylvicultureRésumé : (auteur) Today's forest managers face a number of important challenges involving an increasing need for precise estimates of forest structure and biomass, potential productivity or forest growth. The objective is to develop a model for potential productivity in a mountainous region of Spain. The model combines climatic, topographic and lithological data using a variant of a traditional biophysical model: the Paterson index. • In a first approach, the climatic productivity is assessed by modelling the required parameters using different geostatistical techniques and software supported by GIS. A second approach includes the correction of the former productivity classes considering the different lithological facies. The potential forest productivity model involves the integration of both models. • Finally, data from the National Forest Inventory (NFI) are used to compare the real and potential yield data within different regions of the studied area. • The results of these analyses demonstrate the usefulness of the model, particularly in mountainous regions, where no significant differences are found between the data from the NFI and the model, but they also show the discrepancies between the estimates and real data when the latter are considered for different tree species, diameter classes or management. Numéro de notice : A2009-725 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1051/forest/2008080 Date de publication en ligne : 31/01/2009 En ligne : https://www.afs-journal.org/articles/forest/abs/2009/01/f08123/f08123.html Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=71766
in Annals of Forest Science > Vol 66 n° 1 (January - February 2009) . - n° 108[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité IFN-DIR-P000294 PER Revue Nogent-sur-Vernisson Salle périodiques Exclu du prêt Why and where do adult trees die in a young secondary temperate forest? The role of neighbourhood / José Miguel Olano in Annals of Forest Science, Vol 66 n° 1 (January - February 2009)
[article]
Titre : Why and where do adult trees die in a young secondary temperate forest? The role of neighbourhood Titre original : Pourquoi et où les arbres adultes meurent dans une jeune forêt tempérée ? Le rôle du voisinage Type de document : Article/Communication Auteurs : José Miguel Olano, Auteur ; Nere Amaia Laskurain, Auteur ; Adrián Escudero, Auteur ; Marcelino De La Cruz, Auteur Année de publication : 2009 Article en page(s) : n° 105 Note générale : Bibliographie Langues : Anglais (eng) Descripteur : [Termes IGN] dépérissement
[Termes IGN] forêt tempérée
[Termes IGN] modèle mathématique
[Termes IGN] mortalité
[Termes IGN] peuplement mélangé
[Vedettes matières IGN] SylvicultureRésumé : (auteur) The density and identity of tree neighbourhood is a key factor to explain tree mortality in forests, especially during the stem exclusion phase. $\bullet$ To understand this process, we built a logistic model for mortality in a spatially explicit context, including tree and neighbourhood predictors. Additionally, we used this model to build mortality risk frequency distributions. Finally, we tested this model against a random mortality model to predict the spatial pattern of the forest. $\bullet$ Annual mortality rate was high for pedunculate oak (Quercus robur, 6.99%), moderate for birch (Betula celtiberica, 2.19%) and Pyrenean oak (Q. pyrenaica, 1.58%) and low for beech (Fagus sylvatica, 0.26%). Mortality risk models for pedunculate oak and birch included stem diameter, tree height, canopy position and neighbourhood. Mortality was affected by the specific nature of the neighbourhood showing a clear competitive hierarchy: beech > pedunculate oak > birch. Models based on random mortality and logistic regression model were able to predict the spatial pattern of survivors although logistic regression predictions were more accurate. $\bullet$ Our study highlights how simple models such as the random mortality one may obscure much more complex spatial interactions. Numéro de notice : A2009-724 Affiliation des auteurs : non IGN Thématique : FORET Nature : Article DOI : 10.1051/forest:2008074 Date de publication en ligne : 14/01/2009 En ligne : https://www.afs-journal.org/articles/forest/abs/2009/01/f08212/f08212.html Format de la ressource électronique : url article Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=71763
in Annals of Forest Science > Vol 66 n° 1 (January - February 2009) . - n° 105[article]Exemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité IFN-DIR-P000294 PER Revue Nogent-sur-Vernisson Salle périodiques Exclu du prêt La forêt face aux tempêtes / Yves Birot (2009)
Titre : La forêt face aux tempêtes Type de document : Monographie Auteurs : Yves Birot, Éditeur scientifique ; Guy Landmann, Éditeur scientifique ; Ingrid Bonhême , Éditeur scientifique Editeur : Versailles : Quae Année de publication : 2009 Collection : Synthèses, ISSN 1777-4624 Importance : 433 p. Format : 16 x 24 cm ISBN/ISSN/EAN : 978-2-7592-0330-7 Note générale : Bibliographie Langues : Français (fre) Descripteur : [Termes IGN] Aves
[Termes IGN] carte de la végétation
[Termes IGN] cartographie des risques
[Termes IGN] chablis (sylviculture)
[Termes IGN] dommage matériel
[Termes IGN] écosystème forestier
[Termes IGN] forêt tempérée
[Termes IGN] France (administrative)
[Termes IGN] modèle statistique
[Termes IGN] Picea abies
[Termes IGN] Pinus pinaster
[Termes IGN] prévention des risques
[Termes IGN] Pseudotsuga menziesii
[Termes IGN] Quercus (genre)
[Termes IGN] risque naturel
[Termes IGN] Scolytinae
[Termes IGN] tempête
[Termes IGN] tempête Klaus de 2009
[Termes IGN] tempête Lothar de 1999
[Termes IGN] vent
[Termes IGN] zone sinistrée
[Vedettes matières IGN] Economie forestièreIndex. décimale : 423.5 Santé des forêts [dépérissement, incendies, dégâts dus aux ravageurs ou aux aléas naturels, changement climatique, etc.] Résumé : (Editeur) Les 26 et 27 décembre 1999, Lothar et Martin, deux tempêtes lourdes d'effets ont traversé la France, laissant derrière elles des forêts méconnaissables, des forestiers meurtris et une filière de la forêt et du bois fortement et durablement affectée. Pourquoi les écosystèmes forestiers sont-ils si vulnérables ? Pourquoi de tels aléas se produisent-ils ? Comment en limiter les effets ? Quelques années plus tard, et au lendemain d'une nouvelle tempête, Klaus, qui a frappé le Sud-Ouest du pays, cet ouvrage de synthèse apporte les réponses de la communauté scientifique à ces questions, notamment à travers les résultats du programme de recherche intitulé « Forêt, vent et risque », lancé en 2000 par les Pouvoirs Publics et animé par le Gip Ecofor. Cet ouvrage est destiné au monde forestier, aux gestionnaires, techniciens et professionnels, aux chercheurs, ainsi qu’aux enseignants et aux étudiants. Numéro de notice : 20969 Affiliation des auteurs : non IGN Thématique : FORET Nature : Recueil / ouvrage collectif Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=41854 ContientRéservation
Réserver ce documentExemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité IFN-002-000002 423.5 BIR Livre Bordeaux Bibliothèque Bordeaux IFN Exclu du prêt 20969-01 48.00 Livre Centre de documentation Environnement Disponible IFN-001-000308 423.5 BIR Livre Nogent-sur-Vernisson Bibliothèque Nogent IFN Exclu du prêt
Titre : Regional gravity field modelling with radial basis functions Type de document : Thèse/HDR Auteurs : Tobias Wittwer, Auteur Editeur : Delft : Netherlands Geodetic Commission NGC Année de publication : 2009 Collection : Netherlands Geodetic Commission Publications on Geodesy, ISSN 0165-1706 num. 72 Importance : 190 p. Format : 17 x 24 cm ISBN/ISSN/EAN : 978-90-6132-315-0 Note générale : Bibliographie
Document téléchargeable sur le site de NCG : voir lien dans la noticeLangues : Anglais (eng) Descripteur : [Vedettes matières IGN] Géodésie physique
[Termes IGN] Antarctique
[Termes IGN] Canada
[Termes IGN] champ de pesanteur local
[Termes IGN] données GOCE
[Termes IGN] données GRACE
[Termes IGN] factorisation de Cholesky
[Termes IGN] filtre de Wiener
[Termes IGN] fonction de base radiale
[Termes IGN] Groenland
[Termes IGN] harmonique sphérique
[Termes IGN] levé gravimétrique
[Termes IGN] modèle de géopotentiel
[Termes IGN] modèle mathématiqueIndex. décimale : 30.42 Gravimétrie Résumé : (Auteur) Terrestrial gravimetry, airborne gravimetry, and the recent dedicated satellite gravity missions Challenging Minisatellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity and Ocean Circulation Explorer (GOCE) provide us with high-quality, high-resolution gravity data, which are used in many application areas such as
1. the computation of global static gravity fields, in support of precise orbit determination of many Earth observation satellites;
2. the quantification and interpretation of mass transport in the Earth system such as the shrinking of ice sheets, the shifting of ocean currents, and water storage variations;
3. the computation of high resolution regional and local gravity fields in support of height system realisation and the modelling of reservoirs and geophysical features.
Traditionally, for each data set (satellite, airborne, terrestrial) dedicated data processing schemes have been developed using different estimation principles, parametrisations, etc. The optimal combination of different data sets would benefit of a methodology that can be used for any type of data. Elements of this methodology comprise a uniform parametrisation, estimation principle, data weighting scheme, regularisation, and error propagation.
In the framework of this thesis, such a methodology is developed. It uses radial basis functions (RBFs) as parametrisation. They have parameters that allow us to tune their approximation properties as function of the data coverage and distribution and the signal variations. This makes them equally well suited for global and local parametrisation. Moreover, there exists an analytical relationship between a spherical harmonic representation and a radial basis function representation, which allows the latter to be transformed into the former, without any approximation error. Among others, this has the advantage that one can make use of existing processing tools, such as spectral analysis.
Although radial basis functions are not new in gravity field modelling, there are many important issues which have not yet been addressed or require further research. The main research question underlying this thesis is: "Are radial basis functions a suitable parametrisation for global and regional models of the mean and time-variable gravity field, and if so, how do they perform compared with spherical harmonic solutions?" Directly related to this is the question: "Are there situations where radial basis functions models outperform spherical harmonic solutions?" The answer to both questions is positive as will be shown in this thesis.
There are two important aspects that determine the quality of a gravity field model based on radial basis functions: 1) the spatial distribution of the radial basis functions, i.e. the basis function network design, and 2) the choice of the bandwidths of the radial basis functions. For both problems, semi-automatic algorithms have been developed. Data-adaptive network design and local refinement avoid respectively over- and under-parametrisation by fine-tuning the basis function network based on the data. The basis function bandwidth is determined by optimising the fit to the data including control data.
The computation of regional gravity fields constitutes a considerable numerical workload, especially since the methodology presented here does not use an iterative normal equation solver (e.g., the preconditioned conjugate gradient method). Instead, a Cholesky solver is used, which requires the assembly of the complete normal equation system. For this purpose the program is numerically optimised and fully parallelised for hybrid high performance computer architectures. This guarantees optimal performance on all types of parallel computers and handles the memory requirements.
The modelling of satellite data with radial basis functions is investigated using real data of the GRACE satellites collected over the period 2003-2006. An optimal Wiener filter has been developed for radial basis functions in line with the optimal Wiener filter approach previously developed at DEOS for spherical harmonic representations. Monthly GRACE gravity models computed using radial basis function are compared to spherical harmonic models, and validated using independent data provided by the Ice Cloud and Land Elevation Satellite (ICESat), radar altimetry satellites, and the global hydrological model PCR-GLOBWB. Two applications were considered: 1) mass variations over Greenland and Antarctica and 2) water storage variations in river basins. The results show that the radial basis function approach yields solutions that are of at least the same quality as global models using spherical harmonics. There is evidence that radial basis functions may provide better spatial resolution and more realistic amplitudes in particular in high-latitude areas. For instance, it will be shown that radial basis function solutions detected signal that could not be seen in spherical harmonic solutions.
Two test areas are used for regional gravity field modelling using real terrestrial data: An area in the northeastern USA and a larger area in eastern Canada. The results show that the data-adaptivity and local refinement algorithms developed in the framework of this thesis provide good solutions of constant quality regardless of the initially chosen grid spacing. The models are compared to the official regional geoid models GEOID03 and CGG05, respectively. In both cases, rms errors of several centimetres remain, which are attributed to different input data and processing strategies.
The combination of satellite and terrestrial data is tested using simulated global and regional data sets. It is shown that a joint inversion of the two data sets yields combined solutions which are significantly better than a solution using the traditional remove-restore approach. The addition of satellite data with the corresponding stochastic model compensates the reduced quality of the terrestrial data at long wavelengths.
The examples show that the regional modelling methodology presented here is a very flexible approach that can be applied to all types of gravity data and data distributions, regardless of application, data source, and area size. The quality of the solutions is at least equal to the solutions developed for the stand-alone inversion of individual data sets, while radial basis functions offer numerical benefits. As a result, this approach is already used for marine geoid modelling, and recommended for the modelling of airborne gravity data and data of the GOCE satellite, and for the joint inversion of satellite, airborne and ground-based gravity data.Note de contenu : Nomenclature
1 Introduction
1.1 Background
1.2 Motivation
1.2.1 Regional modelling from satellite data
1.2.2 Regional modelling from terrestrial data
1.2.3 Combined modelling of satellite and terrestrial data
1.2.4 Radial basis functions
1.3 Prior research on radial basis functions
1.4 Research objectives
1.5 Outline of thesis
2 Radial basis functions
2.1 Gravity field representations
2.1.1 Spherical harmonics
2.1.2 Radial basis functions
2.2 RBF types and behaviour in the spectral domain
2.3 Behaviour in the spatial domain
2.4 Relation of RBFs to a spherical harmonic representation
2.5 Choice of RBF characteristics
2.5.1 Choice of the kernel
2.5.2 Bandwidth selection
2.6 RBF network design
2.6.1 Grids
2.6.2 Adaptation to data
2.6.3 Local refinement
2.7 Multi-scale modelling
2.7.1 Introduction
2.7.2 Methodology
2.7.3 Filtering
3 Mathematical model and estimation principle
3.1 Functional model
3.2 Stochastic model
3.3 Least-squares estimation and regularisation
3.4 Solution strategies
3.4.1 Cholesky factorisation
3.4.2 Conjugate gradients
3.5 Variance component estimation .
3.5.1 Normal equations
3.5.2 Variance component estimation
3.5.3 Stochastic trace estimation
4 Numerical aspects
4.1 Numerical optimisation
4.1.1 Constant expressions in "do"-loops
4.1.2 Computation of the design matrix
4.1.3 Normalisation of coordinates
4.1.4 Normalisation of basis functions
4.2 Fast synthesis
4.3 Parallelisation
4.3.1 Problem description
4.3.2 Parallel computer architectures .
4.3.3 Parallelisation for shared memory computers
4.3.4 Parallelisation for distributed memory computers
4.3.5 Hybrid parallelisation
4.3.6 Results of parallelisation
4.4 Summary and conclusions
5 Gravity field modelling from satellite data
5.1 Functional model
5.1.1 Three-point range combination approach
5.1.2 Residual accelerations
5.1.3 Equivalent water heights
5.1.4 Trend and signal amplitude estimation
5.2 Stochastic model
5.3 Optimal filtering
5.3.1 Introduction
5.3.2 Signal covariance matrix computation
5.3.3 Noise level estimation
5.4 RBF network design
5.4.1 Grid choice
5.4.2 Data-adaptivity and local refinement
5.4.3 Parametrised area
5.5 Bandwidth selection
5.6 Results.
5.6.1 Comparison of unfiltered RBF and spherical harmonic solution
5.6.2 Models used for comparison
5.6.3 Recovery of ice mass loss in Greenland and Antarctica
5.6.4 Recovery of terrestrial water storage variations
5.7 Summary and conclusions
6 Local gravity field modelling from terrestrial data
6.1 Functional model
6.1.1 Functional model for gravity disturbances
6.1.2 Functional model for gravity anomalies
6.1.3 Functional model for height anomalies
6.2 RBF network design
6.2.1 Grid choice
6.2.2 Data-adaptivity and local refinement
6.2.3 Parametrised area
6.3 Bandwidth selection
6.4 Results
6.4.1 Northeastern USA
6.4.2 Canada
6.5 Summary and conclusions
7 Combined modelling of satellite and terrestrial data
7.1 Combination strategies
7.1.1 Remove-restore approach
7.1.2 High-pass filtering
7.1.3 Direct combination
7.1.4 Combination with satellite-only solution
7.2 RBF network design and bandwidth selection
7.3 Results
7.3.1 Global test
7.3.2 Regional test
7.4 Summary and conclusions
8 Summary, conclusions and recommendations
8.1 Summary and conclusions
8.2 Recommendations for further researchNuméro de notice : 15511 Affiliation des auteurs : non IGN Thématique : POSITIONNEMENT Nature : Thèse étrangère Note de thèse : PhD thesis En ligne : https://www.ncgeo.nl/index.php/en/publicatiesgb/publications-on-geodesy/item/258 [...] Format de la ressource électronique : URL Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=62744 Réservation
Réserver ce documentExemplaires(1)
Code-barres Cote Support Localisation Section Disponibilité 15511-01 30.42 Livre Centre de documentation Géodésie Disponible Modélisation du bilan hydrique : l'étape clé de la détermination des paramètres et des variables d'entrée / Vincent Badeau ; Nathalie Bréda in Rendez-vous techniques, Hors-série n° 4 (2008)
[article]
Titre : Modélisation du bilan hydrique : l'étape clé de la détermination des paramètres et des variables d'entrée Type de document : Article/Communication Auteurs : Vincent Badeau, Auteur ; Nathalie Bréda, Auteur Année de publication : 2008 Article en page(s) : p. 111-114 Langues : Français (fre) Descripteur : [Termes IGN] bilan hydrique
[Termes IGN] écologie forestière
[Termes IGN] modèle mathématique
[Termes IGN] précipitation
[Termes IGN] Réseau national de suivi à long terme des écosystèmes forestiers RENECOFORNuméro de notice : IFN_2964 Affiliation des auteurs : non IGN Nature : Article DOI : sans Permalink : https://documentation.ensg.eu/index.php?lvl=notice_display&id=71784
in Rendez-vous techniques > Hors-série n° 4 (2008) . - p. 111-114[article]Exemplaires(3)
Code-barres Cote Support Localisation Section Disponibilité IFN-DIR-P000308 PER Revue Nogent-sur-Vernisson Archives périodiques Exclu du prêt IFN-DIR-P000288 PER Revue Nogent-sur-Vernisson Salle périodiques Exclu du prêt IFN-001-P001282 PER Revue Nogent-sur-Vernisson Salle périodiques Exclu du prêt Polar motion modeling, analysis, and prediction with time dependent harmonic coefficients / Huseyin Baki Iz in Journal of geodesy, vol 82 n° 12 (December 2008)PermalinkSynthèse des ateliers. Positionnement du réseau RENECOFOR vis-à-vis de quelques questions et approches émergentes : observation des changements globaux, bioindication et modélisation / Myriam Legay ; Guy Landmann ; Jean-François Dhôte ; François Lebourgeois in Rendez-vous techniques, Hors-série n° 4 (2008)PermalinkWest African Monsoon observed with ground-based GPS receivers during African Monsoon Multidisciplinary Analysis (AMMA) / Olivier Bock in Journal of geophysical research : Atmospheres, vol 113 n° D21 (16 November 2008)PermalinkLes contraintes de croissance dans les tiges : modélisation de leur mise en place et de leur fonction biologique / Tancrède Alméras in Revue forestière française, vol 60 n° 6 (novembre - décembre 2008)PermalinkHydroTools : outil pour la modélisation et l'extraction d'un réseau hydrologique / Imen Hentati in Géomatique expert, n° 65 (01/11/2008)PermalinkA new bioclimatic model calibrated with vegetation for Mediterranean forest areas / Michel Vennetier in Annals of Forest Science, Vol 65 n° 7 (October - November 2008)PermalinkSimulating complex adaptative geographic systems: a geographically aware intelligent agent approach / W. Tang in Cartography and Geographic Information Science, vol 35 n° 4 (October 2008)PermalinkAménagement de la qualité de l'air urbain / Florian Pfäfflin in Géomatique expert, n° 64 (01/09/2008)PermalinkDetection, measurement and prediction of shoreline recession in Accra, Ghana / K. Appeaning Addo in ISPRS Journal of photogrammetry and remote sensing, vol 63 n° 5 (September - October 2008)PermalinkDevelopment of forest carbon stock and wood production in the Czech Republic until 2060 / Emil Cienciala in Annals of Forest Science, Vol 65 n° 6 (September 2008)Permalink