Academic literature on the topic 'Ensembles somme'
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Journal articles on the topic "Ensembles somme"
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Richarté-Manfredi, Chaterine. "Céramiques glaçurées et à décor vert et brun des épaves islamiques de Provence (fin IXe-début Xe siècle)." Arqueología y Territorio Medieval 27 (December 22, 2020): 63–77. http://dx.doi.org/10.17561/aytm.v27.5433.
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Aborder le thème des mobiliers céramiques glaçurés, qui constituent une part, somme toute, assez modeste des cargaisons étudiées des épaves islamiques de Provence, revêt toutefois une importance cruciale en terme de diffusion des techniques et savoir-faire en Méditerranée du haut Moyen Âge. Les produits transportés par les navires à partir des côtes du sud-est et du Levant ibérique permettent de cerner, au plus juste, la datation de ces « ensembles clos » engloutis. Par ailleurs, la confrontation de ces données avec celles du sud-est péninsulaire (Pechina/Alméria) est tout à fait indispensable pour la compréhension de cette dynamique commerciale du haut Moyen Âge méditerranéen.
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Mc Andrew, Marie, and Michel Ledoux. "La concentration ethnique dans les écoles de langue française de l’île de Montréal : un portrait statistique." Cahiers québécois de démographie 24, no. 2 (March 25, 2004): 343–70. http://dx.doi.org/10.7202/010192ar.
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RÉSUMÉ À l'aide d'un indicateur composé qui correspond à la somme des sous-ensembles mutuellement exclusifs des élèves nés à l'étranger ou nés au Québec de parents nés à l'étranger ou allophones, les auteurs analysent le phénomène de la concentration ethnique dans les écoles françaises de l'île de Montréal. La majorité des élèves de cette population cible sont scolarisés dans des écoles où ils constituent plus de 50 % de la clientèle. Cependant, la plupart des écoles comptent plusieurs groupes ethniques, ce qui interdit de parler d'un phénomène de ghettos. Par ailleurs, la concentration ethnique varie énormément selon les commissions scolaires et selon la communauté envisagée, les communautés récentes étant plus concentrées que les anciennes, du moins au secteur français, qui fait seul l'objet de cette étude. Finalement, la mise en rapport de la concentration ethnique avec l'indice de défavorisation des écoles montre que ces deux facteurs ne sont pas corrélês de manière claire.
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DURU, M. "Le volume d’herbe disponible par vache : un indicateur synthétique pour évaluer et conduire un pâturage tournant." INRAE Productions Animales 13, no. 5 (October 22, 2000): 325–36. http://dx.doi.org/10.20870/productions-animales.2000.13.5.3801.
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Gérer un système de pâturage nécessite de définir de manière cohérente trois types de règles. Les règles de planification s’appuient le plus souvent sur des référentiels régionaux (chargement par saison en fonction des apports d’azote). Les règles opératoires (hauteur d’herbe résiduelle, intervalle entre deux utilisations) sont issues d’expérimentations. Les règles d’adaptation ne sont généralement pas spécifiées précisément ; cependant des moyens d’adaptation sont proposés (ajout ou retrait de parcelles) ainsi que des indicateurs de déclenchement de ces adaptations (état de l’herbe par exemple). La difficulté de conduite d’un système de pâturage est de rendre cohérent ces trois ensembles de règles. Il s’agit par exemple de dimensionner la surface allouée par vache de façon à obtenir une hauteur d’herbe résiduelle permettant une efficience agronomique élevée, tout en minimisant les adaptations à faire entre saisons et années.
A partir de suivis de pâturage dans trois réseaux d’élevage, nous montrons que le volume d’herbe disponible par équivalent vache - VHD - (somme des produits surface x hauteur de l’herbe des différentes parcelles, divisée par le nombre de vaches) est un indicateur permettant de relier les différentes règles de conduite du pâturage. En outre, les observations détaillées de la structure de la prairie pâturée pour différentes valeurs de VHD permettent de définir des seuils pour concilier les recommandations à l’échelle de la parcelle et la simplicité de conduite.
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WINDEATT, T., and G. ARDESHIR. "DECISION TREE SIMPLIFICATION FOR CLASSIFIER ENSEMBLES." International Journal of Pattern Recognition and Artificial Intelligence 18, no. 05 (August 2004): 749–76. http://dx.doi.org/10.1142/s021800140400340x.
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The goal of designing an ensemble of simple classifiers is to improve the accuracy of a recognition system. However, the performance of ensemble methods is problem-dependent and the classifier learning algorithm has an important influence on ensemble performance. In particular, base classifiers that are too complex may result in overfitting. In this paper, the performance of Bagging, Boosting and Error-Correcting Output Code (ECOC) is compared for five decision tree pruning methods. A description is given for each of the pruning methods and the ensemble techniques. AdaBoost.OC which is a combination of Boosting and ECOC is compared with the pseudo-loss based version of Boosting, AdaBoost.M2 and the influence of pruning on the performance of the ensembles is studied. Motivated by the result that both pruned and unpruned ensembles made by AdaBoost.OC give similar accuracy, pruned ensembles are compared with ensembles of Decision Stumps. This leads to the hypothesis that ensembles of simple classifiers may give better performance for some problems. Using the application of face recognition, it is shown that an AdaBoost.OC ensemble of Decision Stumps outperforms an ensemble of pruned C4.5 trees for face identification, but is inferior for face verification. The implication is that in some real-world tasks to achieve best accuracy of an ensemble, it may be necessary to select base classifier complexity.
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Hsu, Kuo-Wei. "A Theoretical Analysis of Why Hybrid Ensembles Work." Computational Intelligence and Neuroscience 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/1930702.
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Inspired by the group decision making process, ensembles or combinations of classifiers have been found favorable in a wide variety of application domains. Some researchers propose to use the mixture of two different types of classification algorithms to create a hybrid ensemble. Why does such an ensemble work? The question remains. Following the concept of diversity, which is one of the fundamental elements of the success of ensembles, we conduct a theoretical analysis of why hybrid ensembles work, connecting using different algorithms to accuracy gain. We also conduct experiments on classification performance of hybrid ensembles of classifiers created by decision tree and naïve Bayes classification algorithms, each of which is a top data mining algorithm and often used to create non-hybrid ensembles. Therefore, through this paper, we provide a complement to the theoretical foundation of creating and using hybrid ensembles.
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Li, Peijing, Yun Su, Qianqian Huang, Jun Li, and Jingxian Xu. "Experimental study on the thermal regulation performance of winter uniform used for high school students." Textile Research Journal 89, no. 12 (July 31, 2018): 2316–29. http://dx.doi.org/10.1177/0040517518790977.
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To understand the effectiveness of some garment adjustment designs for high school uniform in winter, manikin tests and subjective wear trials were carried out. Five series of school uniform ensembles were involved in the experiments. They were further collocated into 17 ensemble configurations with detachable designs (ensembles A and B) and opening structures (ensembles C, D, and E). As manikin test results showed, the thermal insulation of ensembles A, B and C varied most significantly due to their adjustment design. The possible thermal insulation regulation levels were approximately 68% and 80% for ensembles A and B, and 60% and 90% for ensemble C. Two human trials that simulated students’ daily movements between indoor and outdoor classes were conducted with ensemble A. Two climate chambers were used at the same time for indoor and outdoor environment simulation. In Case X, where ensemble A was assumed to be non-detachable, skin temperatures that were 0.6℃ lower were finally observed compared to Case Y, where ensemble A was detachable. Moreover, significantly ( p < 0.1) better thermal comfort and thermal sensation evaluations were given during low-intensity activities in Case Y, especially for the torso segments. The detachable high school uniform design was finally proved to be efficient in improving human thermal comfort under various class environments. It was also concluded that more protective measures should be adopted for the hands and face in the school uniform design process.
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Descamps, L., and O. Talagrand. "On Some Aspects of the Definition of Initial Conditions for Ensemble Prediction." Monthly Weather Review 135, no. 9 (September 1, 2007): 3260–72. http://dx.doi.org/10.1175/mwr3452.1.
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Abstract Four methods for initialization of ensemble forecasts are systematically compared, namely the methods of singular vectors (SV) and bred modes (BM), as well as the ensemble Kalman filter (EnKF) and the ensemble transform Kalman filter (ETKF). The comparison is done on synthetic data with two models of the flow, namely, a low-order model introduced by Lorenz and a three-level quasigeostrophic atmospheric model. For the latter, both cases of a perfect and an imperfect model are considered. The performance of the various initialization methods is assessed in terms of the statistical reliability and resolution of the ensuing predictions. The relative performance of the four methods, which is statistically significant to a range of about 6 days, is in the order EnKF > ETKF > BM > SV. The difference between the former two methods and the latter two is on the whole more significant than the differences between EnKF and ETKF, or between BM and SV separately. The general conclusion is that, if the quality of ensemble predictions is assessed by the degree to which the predicted ensembles statistically sample the uncertainty on the future state of the flow, the best initial ensembles are those that best statistically sample the uncertainty on the present state of the flow.
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BERNUI, ARMANDO, THYRSO VILLELA, and IVAN FERREIRA. "ANALYSIS OF THE ANGULAR DISTRIBUTION OF COSMIC OBJECTS." International Journal of Modern Physics D 13, no. 07 (August 2004): 1189–95. http://dx.doi.org/10.1142/s0218271804005304.
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We investigate a method that reveals anisotropies in the angular distribution of cosmic objects. In particular, we investigate ensembles with ~ 1000 objects, which is the interesting case of some astronomical catalogs. Considering test ensembles generated with a variable degree of anisotropy, we calculate the probability of any pair of objects to be separated by a given angular distance and compare this result with the same probability for a purely isotropic ensemble. We show that the use of sub-ensembles of the original full sky test ensemble, namely partial catalogs containing objects in the polar cap regions, can reveal, at any scale, possible angular correlations in the original full sky distribution. We also show the robustness of this method by comparing it with the Kolmogorov–Smirnov and χ2 statistical tests.
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Yamaguchi, Munehiko, and Naohisa Koide. "Tropical Cyclone Genesis Guidance Using the Early Stage Dvorak Analysis and Global Ensembles." Weather and Forecasting 32, no. 6 (November 21, 2017): 2133–41. http://dx.doi.org/10.1175/waf-d-17-0056.1.
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Abstract TC genesis guidance using the early stage Dvorak analysis technique (EDA) and global ensembles is investigated as one of the statistical–dynamical TC genesis guidance schemes. The EDA is a scheme that enables the analysis of tropical disturbances at earlier stages by adding T numbers of 0.0 and 0.5 to the conventional Dvorak technique. This unique analysis method has been in operation at JMA since 2001. The global ensembles used in this study are the ECMWF, JMA, NCEP, and UKMO ensembles covering from 2010 to 2013. First, probabilities that tropical disturbances analyzed with the EDA reach tropical storm intensity within a certain lead time up to 5 days are statistically investigated. For example, the probabilities that a tropical disturbance analyzed with T numbers of 0.0, 0.5, and 1.0 reaches tropical storm intensity within 2 days are 15%, 23%, and 57%, respectively. While the false alarm ratio (FAR) is found to decrease if the global ensembles simulate the tropical disturbance analyzed with the EDA in the models, it tends to decrease with the increasing number of such ensemble members. Also, it should be noted that the probability of detection (POD) decreases with the increasing number of such ensemble members. One of the potential uses of these verification results is that forecasters could issue TC genesis forecasts by counting ensemble members that successfully simulate a targeted tropical disturbance and then refer to the FAR and POD corresponding to the number of the ensemble members. These would provide some confidence information of the forecasts.
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Velázquez, J. A., F. Anctil, and C. Perrin. "Performance and reliability of multimodel hydrological ensemble simulations based on seventeen lumped models and a thousand catchments." Hydrology and Earth System Sciences 14, no. 11 (November 18, 2010): 2303–17. http://dx.doi.org/10.5194/hess-14-2303-2010.
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Abstract. This work investigates the added value of ensembles constructed from seventeen lumped hydrological models against their simple average counterparts. It is thus hypothesized that there is more information provided by all the outputs of these models than by their single aggregated predictors. For all available 1061 catchments, results showed that the mean continuous ranked probability score of the ensemble simulations were better than the mean average error of the aggregated simulations, confirming the added value of retaining all the components of the model outputs. Reliability of the simulation ensembles is also achieved for about 30% of the catchments, as assessed by rank histograms and reliability plots. Nonetheless this imperfection, the ensemble simulations were shown to have better skills than the deterministic simulations at discriminating between events and non-events, as confirmed by relative operating characteristic scores especially for larger streamflows. From 7 to 10 models are deemed sufficient to construct ensembles with improved performance, based on a genetic algorithm search optimizing the continuous ranked probability score. In fact, many model subsets were found improving the performance of the reference ensemble. This is thus not essential to implement as much as seventeen lumped hydrological models. The gain in performance of the optimized subsets is accompanied by some improvement of the ensemble reliability in most cases. Nonetheless, a calibration of the predictive distribution is still needed for many catchments.
Dissertations / Theses on the topic "Ensembles somme"
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He, Weikun. "Sommes, produits et projections des ensembles discrétisés." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS335/document.
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Dans le cadre discrétisé, la taille d'un ensemble à l'échelle δ est évaluée par son nombre de recouvrement par δ-boules (également connu sous le nom de l'entropie métrique). Dans cette thèse, nous étudions les propriétés combinatoires des ensembles discrétisés sous l'addition, la multiplication et les projections orthogonales. Il y a trois parties principales. Premièrement, nous démontrons un théorème somme-produit dans les algèbres de matrices, qui généralise un théorème somme-produit de Bourgain concernant l'anneau des réels. On améliore aussi des estimées somme-produit en dimension supérieure obtenues précédemment par Bougain et Gamburd. Deuxièmement, on étudie les projections orthogonales des sous-ensembles de l'espace euclidien et étend ainsi le théorème de projection discrétisé de Bourgain aux projections de rang supérieur. Enfin, dans un travail en commun avec Nicolas de Saxcé, nous démontrons un théorème produit dans les groupes de Lie parfaits. Ce dernier résultat généralise les travaux antérieurs de Bourgain-Gamburd et de SaxcéIn the discretized setting, the size of a set is measured by its covering number by δ-balls (a.k.a. metric entropy), where δ is the scale. In this document, we investigate combinatorial properties of discretized sets under addition, multiplication and orthogonal projection. There are three parts. First, we prove sum-product estimates in matrix algebras, generalizing Bourgain's sum-product theorem in the ring of real numbers and improving higher dimensional sum-product estimates previously obtained by Bourgain-Gamburd. Then, we study orthogonal projections of subsets in the Euclidean space, generalizing Bourgain's discretized projection theorem to higher rank situations. Finally, in a joint work with Nicolas de Saxcé, we prove a product theorem for perfect Lie groups, generalizing previous results of Bourgain-Gamburd and Saxcé
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Henriot, Kevin. "Structures linéaires dans les ensembles à faible densité." Thèse, Paris 7, 2014. http://hdl.handle.net/1866/11116.
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Réalisé en cotutelle avec l'Université Paris-Diderot.Nous présentons trois résultats en combinatoire additive, un domaine récent à la croisée de la combinatoire, l'analyse harmonique et la théorie analytique des nombres. Le thème unificateur de notre thèse est la détection de structures additives dans les ensembles arithmétiques à faible densité, avec un intérêt particulier pour les aspects quantitatifs. Notre première contribution est une estimation de densité améliorée pour le problème, initié entre autres par Bourgain, de trouver une longue progression arithmétique dans un ensemble somme triple. Notre deuxième résultat consiste en une généralisation des bornes de Sanders pour le théorème de Roth, du cas d'un ensemble dense dans les entiers à celui d'un ensemble à faible croissance additive dans un groupe abélien arbitraire. Finalement, nous étendons les meilleures bornes quantitatives connues pour le théorème de Roth dans les premiers, à tous les systèmes d'équations linéaires invariants par translation et de complexité un.
We present three results in additive combinatorics, a recent field at the interface of combinatorics, harmonic analysis and analytic number theory. The unifying theme in our thesis is the detection of additive structure in arithmetic sets of low density, with an emphasis on quantitative aspects. Our first contribution is an improved density estimate for the problem, initiated by Bourgain and others, of finding a long arithmetic progression in a triple sumset. Our second result is a generalization of Sanders' bounds for Roth's theorem from the dense setting, to the setting of small doubling in an arbitrary abelian group. Finally, we extend the best known quantitative results for Roth's theorem in the primes, to all translation-invariant systems of equations of complexity one.
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Anglès, d'Auriac Jean-Alexandre. "Jeux de défense et ensembles tropicaux." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112235/document.
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Le premier volet de cette thèse porte sur l'étude de graphes dont les sommets sont colorés. Nous étudions comment la recherche d'ensembles particuliers de sommets est affectée lorsqu'on ajoute la contrainte qu'ils soient tropicaux, c'est à dire contiennent au moins un sommet de chacune des couleurs.Cette contrainte additionnelle tend à fortement augmenter la complexité des problèmes. Par exemple, la recherche d'un plus petit ensemble dominant tropical, et celle d'une plus petite couverture par sommet tropicale, sont APX-complets même restreints aux chemins. La recherche du plus petit sous-graphe connexe tropical d'un graphe est elle NP-complète, même restreinte aux arbres. Cependant, ajouter un contrainte sur le nombre de couleurs permet souvent de réduire la complexité. Par exemple, sans restrictions sur le type de graphes en entrée, la recherche d'un sous-graphe connexe tropical s'effectue en temps polynomial pourvu que le nombre de couleurs reste logarithmique en la taille du graphe. De plus, nous montrons divers résultats structurels qui lient la taille d'un sous-graphe connexe tropical minimum à des paramètres du graphe tels que le nombre de couleurs, le nombre d'arêtes, le degré minimum, ... Dans le second volet, nous étudions des jeux sur des graphes, appelés jeux de défense, où des attaquants ciblent des sommets et des défenseurs protègent des sous-graphes. On s'intéresse à l'existence d'un équilibre de Nash lorsque les défenseurs protègent des chemins de taille au plus p. Lorsque chaque défenseur protège exactement une arête, nous montronThe first pane of this thesis is on the study of vertex-colored graphs. We look at the tractability of asserting the existence of particular sets of vertices on a graph with the added constraint that the sets must be tropical, i.e. they must contain at least one vertex of each of the colors in the graph.This additional constraint tends to make the problems way less tractable. For instance, finding a minimum tropical dominating set, or a minimum tropical vertex cover, are APX-complete problems even when restricted to paths. Finding the smallest tropical connected subgraph is also NP-complete even when restricted to trees. However, restricting the number of colors will usually make problems more tractable. For instance, finding a connected tropical subgraph (on any graph) can be done in polynomial time as long as the number of colors is logarithmic in the size of the graph. Moreover, we show some structural results that links the size of a minimum connected subgraph to parameters such as the number of colors, the number of edges, the minimum degree…The second pane is on the study of some games on graphs, called defense games, in which multiple attackers target vertices and multiple defenders protect subgraphs.We focus on the existence of a Nash equilibrium when defenders protect paths of size at most p.When each defender protects exactly one edge, we show among other results that the game on a graph G with n defenders and k attackers admits a Nash equilibrium if and only if there exists a dominating set of size at most k in G, which is NP-complete in the general case.Similarly, when each defender protects a path of size at most p, the existence of a Nash equilibrium is linked to the notion of p-independent, i.e. a set of vertices such that every pair of elements of the set is at distance greater than p.Determining the existence of a maximal p-independent of size at most k is NP-complete, but our Min2stablemax algorithm can compute the minimum size of a maximal 2-independent set in a tree
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Silipo, James. "Systèmes de sommes d'exponentielles à spectres réels et structure de leurs amibes." Bordeaux 1, 2005. http://www.theses.fr/2005BOR13006.
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Le but de ce travail est d'étudier la notion d'amibe (dans le sens de Favorov) pour un système F des sommes d'exponentielles de n-variables complexes et à fréquences réelles génériques. À l'aide d'une perturbation par caractères du groupe des fréquences de F, on obtient une expression de l'amibe de F qui nous permet d'en étudier la topologie. En particulier on montre que, si F est constitué par (k+1) éléments, le complémentaire de l'amibe de F est un sous-ensemble k-convexe de R^n. Ce résultat généralise l'analogue algébrique montré par Henriques. En outre, dans le cas d'une seule somme d'exponentielles f, on envisage les rapports entre l'amibe de f et sa fonction de RonkinThe aim of this work is to study the notion of amoeba (in the sense of Favorov) for a system F of exponential sums of n complex variables and real generic frequencies. Thanks to a perturbation by characters of the group of frequencies of F, we obtain a expression of the amoeba of F which is useful in the study of its topology. In particular, we show that, if F has (k+1) elements, the complementary set to the amoeba of F is a k-convex subset of R^n in Henriques' sense. This result generalize the algebraic analog shown by Henriques. Moreover, in the case of one exponential sum f, we investigate the relations between the amoeba of f and its Ronkin function
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Plagne, Alain. "Points entiers sur les courbes strictement convexes, sommes de sous-ensembles et codes de recouvrement." Bordeaux 1, 1998. http://www.theses.fr/1998BOR10633.
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Etendant le resultat de jarnik, nous montrons que pour toute fonction x tendant vers l'infini, il est possible de construire une courbe strictement convexe c telle que l'intersection de c et du reseau (1/q z)2 contienne plus d'une constante fois q2/3/x(q) elements, et ceci pour une infinite de valeurs de q. Nous montrons aussi comment, grace a des methodes provenant de la theorie analytique des nombres, on peut etendre les travaux de freiman, sur les sommes de sous-ensembles en dimension 2. Independamment, on caracterise tres precisement les sous-ensembles de (z/2z)n ayant un petit double. Enfin, nous nous interessons aux bornes inferieures pour le cardinal d'un code de rayon de recouvrement donne r dans l'espace f#n#q. Nous obtenons un grand nombre de nouvelles bornes, ameliorant ainsi pres de 20% des cas etudies par la litterature.
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Wang, Simeng. "Some problems in harmonic analysis on quantum groups." Thesis, Besançon, 2016. http://www.theses.fr/2016BESA2062/document.
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Cette thèse étudie quelques problèmes d’analyse harmonique sur les groupes quantiques compacts. Elle consiste en trois parties. La première partie présente la théorie Lp élémentaire des transformées de Fourier, les convolutions et les multiplicateurs sur les groupes quantiques compacts, y compris la théorie de Hausdorff-Young et les inégalités de Young.Dans la seconde partie, nous caractérisons les opérateurs de convolution positifs sur un groupe quantique fini qui envoient Lp dans L2, et donnons aussi quelques constructions sur les groupes quantiques compacts infinis. La méthode pour étudier les états non-dégénérés fournit une formule générale pour calculer les états idempotents associés aux images deHopf, qui généralise un travail de Banica, Franz et Skalski. La troisième partie est consacrée à l’étude des ensembles de Sidon, des ensembles _(p) et des notions associées pour les groupes quantiques compacts. Nous établissons différentes caractérisations des ensembles de Sidon, et en particulier nous démontrons que tout ensemble de Sidon est un ensemble de Sidon fort au sens de Picardello. Nous donnons quelques liens entre les ensembles de Sidon, les ensembles _(p) et les lacunarités pour les multiplicateurs de Fourier sur Lp, généralisant un travail de Blendek et Michali˘cek. Nous démontrons aussi l’existence des ensembles de type _(p) pour les systèmes orthogonaux dans les espaces Lp non commutatifs, et déduisons les propriétés correspondantes pour les groupes quantiques compacts. Nous considérons aussi les ensembles de Sidon centraux, et nous prouvons que les groupes quantiques compacts ayant les mêmes règles de fusion et les mêmes fonctions de dimension ont des ensemble de Sidon centraux identiques. Quelques exemples sont aussi étudiés dans cette thèse. Les travaux présentés dans cette thèse se basent sur deux articles de l’auteur. Le premier s’intitule “Lp-improving convolution operators on finite quantum groups” et a été accepté pour publication dans Indiana University Mathematics Journal, et le deuxième est un travail intitulé “Lacunary Fourier series for compact quantum groups” et a été publié en ligne dans Communications in Mathematical PhysicsThis thesis studies some problems in the theory of harmonic analysis on compact quantum groups. It consists of three parts. The first part presents some elementary Lp theory of Fourier transforms, convolutions and multipliers on compact quantum groups, including the Hausdorff-Young theory and Young’s inequalities. In the second part, we characterize positive convolution operators on a finite quantum group G which are Lp-improving, and also give some constructions on infinite compact quantum groups. The methods for ondegeneratestates yield a general formula for computing idempotent states associated to Hopf images, which generalizes earlier work of Banica, Franz and Skalski. The third part is devoted to the study of Sidon sets, _(p)-sets and some related notions for compact quantum groups. We establish several different characterizations of Sidon sets, and in particular prove that any Sidon set in a discrete group is a strong Sidon set in the sense of Picardello. We give several relations between Sidon sets, _(p)-sets and lacunarities for Lp-Fourier multipliers, generalizing a previous work by Blendek and Michali˘cek. We also prove the existence of _(p)-sets for orthogonal systems in noncommutative Lp-spaces, and deduce the corresponding properties for compact quantum groups. Central Sidon sets are also discussed, and it turns out that the compact quantum groups with the same fusion rules and the same dimension functions have identical central Sidon sets. Several examples are also included. The thesis is principally based on two works by the author, entitled “Lp-improvingconvolution operators on finite quantum groups” and “Lacunary Fourier series for compact quantum groups”, which have been accepted for publication in Indiana University Mathematics Journal and Communications in Mathematical Physics respectively
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Nungesser, Ernesto [Verfasser]. "The future of some Bianchi A spacetimes with an ensemble of free falling particles / Ernesto Nungesser." Berlin : Freie Universität Berlin, 2012. http://d-nb.info/1027308546/34.
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Lavie, Marc. "Contribution à l'étude de la convergence de sommes d'ensembles aléatoires indépendants et de martingales multivoques." Montpellier 2, 1990. http://www.theses.fr/1990MON20030.
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Differents modes de convergence sont etudies pour des sommes d'ensembles aleatoires independants a valeurs convexes fermes bornes. On definit la fonction caracteristiques d'un ensemble aleatoire et on etudie ses proprietes. Une topologie, introduite par beer, est etudiee sur l'ensemble des parties convexes fermees bornees d'un espace de banach separable. Elle est moins fine que la topologie de hausdorff et plus fine que la topologie de mosco. Plusieurs theoremes de convergence de martingales multivoques sont donnes
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Latreche, Wissam. "Some aspects on sweeping processes." Thesis, Perpignan, 2018. http://www.theses.fr/2018PERP0011/document.
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Dans cette thèse, on s'intéresse à l'étude d'existence de solutions pour les processus de rafle. Ce problème prend la forme d'une inclusion différentielle contrainte avec des cônes normaux qui apparaissent naturellement dans nombreuses applications telles que le mouvement de foule, l'élastoplasticité, les mécaniques, les circuits électroniques, etc. L'objective de ce travail est de rapprocher deux importantes classes d'inclusions différentielles. D'une part, nous établissons quelques résultats d'existence de tube-solutions pour des processus de rafle à des ensembles uniformément prox-réguliers. D'autre part, nous présentons des résultats d'existence de solutions monotone par rapport à un préordre pour un système mixte d'inclusions différentielles projetées. De plus, nous montrons l'existence d'un point-selle pour notre système et nous fournissons deux exemples d'applicationsIn this thesis, we were interested in the study of the existence of solutions for sweeping processes. This problem takes the form of a constrained differential inclusion involving normal cones which appears naturally in many applications such as crowd motion, elastoplasticity, mechanics, electrical circuit, etc.The aim of this work is to bring together two classes of differential inclusions. On one hand, we establish some existence results of solutions-tube for sweeping processes with uniformly prox-regular sets. On the other hand, we present existence results of monotone solutions with respect to a preorder for a mixed system of projected differential inclusions. In addition, we show that our system has a saddle-point and we provide two examples of applications
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Hanine, Abdelouahab. "Cyclic vectors in some spaces of analytic functions." Thesis, Aix-Marseille, 2013. http://www.theses.fr/2013AIXM4725.
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Cette thèse est consacrée à l'étude du problème de la cyclicité dans certains espaces de fonctions analytiques sur le disque unité. Nous nous intéressons aux espaces de type Bergman et aux espaces de type Korenblum. Dans la première partie, nous étudions les fonctions cycliques dans les espaces de type Korenblum en utilisant la notion des prémesures. Cette notion a été introduite et développée par B. Korenblum au début des années 1970s. En particulier, nous donnons une réponse positive à une conjecture énoncée par C. Deninger. Dans la deuxième partie, nous utilisons la méthode de la résolvante pour étudier la cyclicité des fonctions intérieures singulières associées aux mesures de Dirac dans les espaces de type Bergman à poidsIn this thesis, we study the cyclicity problem in some spaces of analytic functions on the open unit disc. We focus our attention on Korenblum type spaces and on weighted Bergman type spaces. First, we use the technique of premeasures, introduced and developed by Korenblum in the 1970-s and the 1980-s, to give a characterization of cyclic functions in the Korenblum type spaces. In particular, we give a positive answer to a conjecture by Deninger. Second, we use the so called resolvent transform method to study the cyclicity of the one point mass singular inner function in weighted Bergman type spaces, especially with weights depending on the distance to a subset of the unit circle
Books on the topic "Ensembles somme"
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MENC, the National Association for Music Education (U.S.), ed. The jazz ensemble companion: A guide to outstanding big band arrangements selected by some of the foremost jazz educators. Lanham, [Md.]: Rowman & Littlefield Education, 2009.
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Ferrari, Patrik L., and Herbert Spohn. Random matrices and Laplacian growth. Edited by Gernot Akemann, Jinho Baik, and Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.39.
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This article reviews the theory of random matrices with eigenvalues distributed in the complex plane and more general ‘beta ensembles’ (logarithmic gases in 2D). It first considers two ensembles of random matrices with complex eigenvalues: ensemble C of general complex matrices and ensemble N of normal matrices. In particular, it describes the Dyson gas picture for ensembles of matrices with general complex eigenvalues distributed on the plane. It then presents some general exact relations for correlation functions valid for any values of N and β before analysing the distribution and correlations of the eigenvalues in the large N limit. Using the technique of boundary value problems in two dimensions and elements of the potential theory, the article demonstrates that the finite-time blow-up (a cusp–like singularity) of the Laplacian growth with zero surface tension is a critical point of the normal and complex matrix models.
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Keating, Jon, and Nina Snaith. Random permutations and related topics. Edited by Gernot Akemann, Jinho Baik, and Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.25.
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This article considers some topics in random permutations and random partitions highlighting analogies with random matrix theory (RMT). An ensemble of random permutations is determined by a probability distribution on Sn, the set of permutations of [n] := {1, 2, . . . , n}. In many ways, the symmetric group Sn is linked to classical matrix groups. Ensembles of random permutations should be given the same treatment as random matrix ensembles, such as the ensembles of classical compact groups and symmetric spaces of compact type with normalized invariant measure. The article first describes the Ewens measures, virtual permutations, and the Poisson-Dirichlet distributions before discussing results related to the Plancherel measure on the set of equivalence classes of irreducible representations of Sn and its consecutive generalizations: the z-measures and the Schur measures.
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Coolen, A. C. C., A. Annibale, and E. S. Roberts. Random graph ensembles. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198709893.003.0003.
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This chapter presents some theoretical tools for defining random graph ensembles systematically via soft or hard topological constraints including working through some properties of the Erdös-Rényi random graph ensemble, which is the simplest non-trivial random graph ensemble where links appear between two nodes with a fixed probability p. The chapter sets out the central representation of graph generation as the result of a discrete-time Markovian stochastic process. This unites the two flavours of graph generation approaches – because they can be viewed as simply moving forwards or backwards through this representation. It is possible to define a random graph by an algorithm, and then calculate the associated stationary probability. The alternative approach is to specify sampling weights and then to construct an algorithm that will have these weights as the stationary probabilities upon convergence.
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Dyson, Freeman. Spectral statistics of unitary ensembles. Edited by Gernot Akemann, Jinho Baik, and Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.4.
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This article focuses on the use of the orthogonal polynomial method for computing correlation functions, cluster functions, gap probability, Janossy density, and spacing distributions for the eigenvalues of matrix ensembles with unitary-invariant probability law. It first considers the classical families of orthogonal polynomials (Hermite, Laguerre, and Jacobi) and some corresponding unitary ensembles before discussing the statistical properties of N-tuples of real numbers. It then reviews the definitions of basic statistical quantities and demonstrates how their distributions can be made explicit in terms of orthogonal polynomials. It also describes the k-point correlation function, Fredholm determinants of finite-rank kernels, and resolvent kernels.
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Sanderson, Benjamin Mark. Uncertainty Quantification in Multi-Model Ensembles. Oxford University Press, 2018. http://dx.doi.org/10.1093/acrefore/9780190228620.013.707.
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Long-term planning for many sectors of society—including infrastructure, human health, agriculture, food security, water supply, insurance, conflict, and migration—requires an assessment of the range of possible futures which the planet might experience. Unlike short-term forecasts for which validation data exists for comparing forecast to observation, long-term forecasts have almost no validation data. As a result, researchers must rely on supporting evidence to make their projections. A review of methods for quantifying the uncertainty of climate predictions is given. The primary tool for quantifying these uncertainties are climate models, which attempt to model all the relevant processes that are important in climate change. However, neither the construction nor calibration of climate models is perfect, and therefore the uncertainties due to model errors must also be taken into account in the uncertainty quantification.Typically, prediction uncertainty is quantified by generating ensembles of solutions from climate models to span possible futures. For instance, initial condition uncertainty is quantified by generating an ensemble of initial states that are consistent with available observations and then integrating the climate model starting from each initial condition. A climate model is itself subject to uncertain choices in modeling certain physical processes. Some of these choices can be sampled using so-called perturbed physics ensembles, whereby uncertain parameters or structural switches are perturbed within a single climate model framework. For a variety of reasons, there is a strong reliance on so-called ensembles of opportunity, which are multi-model ensembles (MMEs) formed by collecting predictions from different climate modeling centers, each using a potentially different framework to represent relevant processes for climate change. The most extensive collection of these MMEs is associated with the Coupled Model Intercomparison Project (CMIP). However, the component models have biases, simplifications, and interdependencies that must be taken into account when making formal risk assessments. Techniques and concepts for integrating model projections in MMEs are reviewed, including differing paradigms of ensembles and how they relate to observations and reality. Aspects of these conceptual issues then inform the more practical matters of how to combine and weight model projections to best represent the uncertainties associated with projected climate change.
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Hagberg, Garry L. The ensemble as plural subject. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780199355914.003.0025.
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Group jazz improvisation at the highest levels can achieve a kind of cooperative creativity that rises above the sum total of the contributions of the individuals. This phenomenon is widely recognized, but has resisted description beyond metaphors that refer to ‘special chemistry’ and the like. Some recent work in the philosophy of social action, on collective intention and group cognition, and on what has been helpfully called a ‘plural subject’, is brought together in this chapter with a close listening to the Stan Getz Quartet’s performance of the classic standard ‘On Green Dolphin Street’. As with discussions of group action in recent philosophical writings, here it emerges that qualities of the improvised performance are not reducible to individuated intentional content, and the notion of the plural subject provides both an analysis of it and the language for it.
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Speicher, Roland. Random banded and sparse matrices. Edited by Gernot Akemann, Jinho Baik, and Philippe Di Francesco. Oxford University Press, 2018. http://dx.doi.org/10.1093/oxfordhb/9780198744191.013.23.
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This article discusses some mathematical results and conjectures about random band matrix ensembles (RBM) and sparse matrix ensembles. Spectral problems of RBM and sparse matrices can be expressed in terms of supersymmetric (SUSY) statistical mechanics that provides a dual representation for disordered quantum systems. This representation offers important insights into nonperturbative aspects of the spectrum and eigenfunctions of RBM. The article first presents the definition of RBM ensembles before considering the density of states, the behaviour of eigenvectors, and eigenvalue statistics for RBM and sparse random matrices. In particular, it highlights the relations with random Schrödinger (RS) and the role of the dimension of the lattice. It also describes the connection between RBM and statistical mechanics, the spectral theory of large random sparse matrices, conjectures and theorems about eigenvectors and local spacing statistics, and the RS operator on the Cayley tree or Bethe lattice.
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Henley, Jennie. The Musical Lives of Self-Confessed Nonmusicians. Edited by Roger Mantie and Gareth Dylan Smith. Oxford University Press, 2017. http://dx.doi.org/10.1093/oxfordhb/9780190244705.013.14.
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This chapter explores the musical lives of adults who do not class themselves as musicians. A U.K. research study investigating the learning processes within an ensemble found that many adults who learned to play an instrument in an ensemble not only did not class themselves as musicians, but they actively used nonmusical identities to continue and deepen their engagement in adult music making. The chapter looks at the stories of some of the study’s participants. Musical opportunities in adulthood are considered and the socio-cultural environment of an ensemble is discussed through the lens of Cultural Historical Activity Theory (CHAT). The concept of possible selves as a motivator in learning is considered in relation to theoretical perspectives of musical identity. Then, the music lives of different adults are viewed through a framework of being a musician. Finally, ways are considered in which different possible selves and nonmusical identities drive music making.
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Eynard, Bertrand. Random matrices and loop equations. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780198797319.003.0007.
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This chapter is an introduction to algebraic methods in random matrix theory (RMT). In the first section, the random matrix ensembles are introduced and it is shown that going beyond the usual Wigner ensembles can be very useful, in particular by allowing eigenvalues to lie on some paths in the complex plane rather than on the real axis. As a detailed example, the Plancherel model is considered from the point of RMT. The second section is devoted to the saddle-point approximation, also called the Coulomb gas method. This leads to a system of algebraic equations, the solution of which leads to an algebraic curve called the ‘spectral curve’ which determines the large N expansion of all observables in a geometric way. Finally, the third section introduces the ‘loop equations’ (i.e., Schwinger–Dyson equations associated with matrix models), which can be solved recursively (i.e., order by order in a semi-classical expansion) by a universal recursion: the ‘topological recursion’.
Book chapters on the topic "Ensembles somme"
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Torres-Sospedra, Joaquín, Carlos Hernández-Espinosa, and Mercedes Fernández-Redondo. "Ensembles of Multilayer Feedforward: Some New Results." In Computational Intelligence and Bioinspired Systems, 604–11. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/11494669_74.
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Hernández-Espinosa, Carlos, Mercedes Fernández-Redondo, and Joaquín Torres-Sospedra. "Some Experiments on Ensembles of Neural Networks for Hyperspectral Image Classification." In Lecture Notes in Computer Science, 677–84. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-30132-5_93.
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Naimark, O. B. "Collective Behavior of Defect Ensembles and Some Nonlinear Aspects of Failure." In Thermodynamics, Microstructures and Plasticity, 345–62. Dordrecht: Springer Netherlands, 2003. http://dx.doi.org/10.1007/978-94-010-0219-6_22.
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Li, Zhuan, Ping-ping Li, and Hong-min Wang. "Manipulating Some Entangled States with a Three-Λ Atomic Ensemble." In Lecture Notes in Electrical Engineering, 473–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-25541-0_60.
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Hernández-Espinosa, Carlos, Mercedes Fernández-Redondo, and Joaquín Torres-Sospedra. "Some Experiments with Ensembles of Neural Networks for Classification of Hyperspectral Images." In Advances in Neural Networks – ISNN 2004, 912–17. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-28647-9_150.
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Brown, Gavin. "Some Thoughts at the Interface of Ensemble Methods and Feature Selection." In Multiple Classifier Systems, 314. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-12127-2_32.
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Naimark, O. B. "Kinetic Transitions in Ensembles of Defects (Microcracks) and Some Nonlinear Aspects of Fracture." In IUTAM Symposium on Nonlinear Analysis of Fracture, 285–98. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-011-5642-4_27.
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Dela Haije, Tom, and Aasa Feragen. "Conceptual Parallels Between Stochastic Geometry and Diffusion-Weighted MRI." In Mathematics and Visualization, 193–202. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-56215-1_9.
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AbstractDiffusion-weighted magnetic resonance imaging (MRI) is sensitive to ensemble-averaged molecular displacements, which provide valuable information on e.g. structural anisotropy in brain tissue. However, a concrete interpretation of diffusion-weighted MRI data in terms of physiological or structural parameters turns out to be extremely challenging. One of the main reasons for this is the multi-scale nature of the diffusion-weighted signal, as it is sensitive to the microscopic motion of particles averaged over macroscopic volumes. In order to analyze the geometrical patterns that occur in (diffusion-weighted measurements of) biological tissue and many other structures, we may invoke tools from the field of stochastic geometry. Stochastic geometry describes statistical methods and models that apply to random geometrical patterns of which we may only know the distribution. Despite its many uses in geology, astronomy, telecommunications, etc., its application in diffusion-weighted MRI has so far remained limited. In this work we review some fundamental results in the field of diffusion-weighted MRI from a stochastic geometrical perspective, and discuss briefly for which other questions stochastic geometry may prove useful. The observations presented in this paper are partly inspired by the Workshop on Diffusion MRI and Stochastic Geometry held at Sandbjerg Estate (Denmark) in 2019, which aimed to foster communication and collaboration between the two fields of research.
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Jahnke, T., V. Mergel, O. Jagutzki, A. Czasch, K. Ullmann, R. Ali, V. Frohne, et al. "High-Resolution Momentum Imaging—From Stern’s Molecular Beam Method to the COLTRIMS Reaction Microscope." In Molecular Beams in Physics and Chemistry, 375–441. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63963-1_18.
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AbstractMulti-particle momentum imaging experiments are now capable of providing detailed information on the properties and the dynamics of quantum systems in Atomic, Molecular and Photon (AMO) physics. Historically, Otto Stern can be considered the pioneer of high-resolution momentum measurements of particles moving in a vacuum and he was the first to obtain sub-atomic unit (a.u.) momentum resolution (Schmidt-Böcking et al. in The precision limits in a single-event quantum measurement of electron momentum and position, these proceedings [1]). A major contribution to modern experimental atomic and molecular physics was his so-called molecular beam method [2], which Stern developed and employed in his experiments. With this method he discovered several fundamental properties of atoms, molecules and nuclei [2, 3]. As corresponding particle detection techniques were lacking during his time, he was only able to observe the averaged footprints of large particle ensembles. Today it is routinely possible to measure the momenta of single particles, because of the tremendous progress in single particle detection and data acquisition electronics. A “state-of-the-art” COLTRIMS reaction microscope [4–11] can measure, for example, the momenta of several particles ejected in the same quantum process in coincidence with sub-a.u. momentum resolution. Such setups can be used to visualize the dynamics of quantum reactions and image the entangled motion of electrons inside atoms and molecules. This review will briefly summarize Stern’s work and then present in longer detail the historic steps of the development of the COLTRIMS reaction microscope. Furthermore, some benchmark results are shown which initially paved the way for a broad acceptance of the COLTRIMS approach. Finally, a small selection of milestone work is presented which has been performed during the last two decades.
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Huettmann, Falk. "Boosting, Bagging and Ensembles in the Real World: An Overview, some Explanations and a Practical Synthesis for Holistic Global Wildlife Conservation Applications Based on Machine Learning with Decision Trees." In Machine Learning for Ecology and Sustainable Natural Resource Management, 63–83. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-96978-7_3.
Full textConference papers on the topic "Ensembles somme"
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Kieu, Tung, Bin Yang, Chenjuan Guo, and Christian S. Jensen. "Outlier Detection for Time Series with Recurrent Autoencoder Ensembles." In Twenty-Eighth International Joint Conference on Artificial Intelligence {IJCAI-19}. California: International Joint Conferences on Artificial Intelligence Organization, 2019. http://dx.doi.org/10.24963/ijcai.2019/378.
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We propose two solutions to outlier detection in time series based on recurrent autoencoder ensembles. The solutions exploit autoencoders built using sparsely-connected recurrent neural networks (S-RNNs). Such networks make it possible to generate multiple autoencoders with different neural network connection structures. The two solutions are ensemble frameworks, specifically an independent framework and a shared framework, both of which combine multiple S-RNN based autoencoders to enable outlier detection. This ensemble-based approach aims to reduce the effects of some autoencoders being overfitted to outliers, this way improving overall detection quality. Experiments with two large real-world time series data sets, including univariate and multivariate time series, offer insight into the design properties of the proposed frameworks and demonstrate that the resulting solutions are capable of outperforming both baselines and the state-of-the-art methods.
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Lee, Jiyoon, and Jonggeun Choe. "Reliable Reservoir Characterization and History Matching Using a Pattern Recognition Based Distance." In ASME 2016 35th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/omae2016-54287.
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A distance is defined as a measure of dissimilarity between two reservoir models. There have been many distances proposed for fast modeling. However, some distances cause distortion or loss in original permeability distribution of models. To avoid such problems, this study proposes a pattern recognition based distance. The distance is defined by the difference of correlation coefficients between ensemble models. From multi-dimensional scaling, initial 400 ensembles are presented on 2D plane using the distance. Then 10 groups are made by K-medoids clustering. After comparing oil production from each centroid and that of the reference field, 100 models are selected around the best centroid. We validate the clustering by comparing the uncertainty range of 100, 50, and 20 ensemble members sampled from the initial 400 models in box plots and cumulative distribution functions. For a history matching and reservoir characterization, ensemble smoother is applied to the 100 models selected. The proposed method takes only 25% time for simulation showing reliable results compared with the initial 400 models.
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Silva, Roberto, Bruna Barreira, Fernando Xavier, Antonio Saraiva, and Carlos Cugnasca. "Use of econometrics and machine learning models to predict the number of new cases per day of COVID-19." In Anais Principais do Simpósio Brasileiro de Computação Aplicada à Saúde. Sociedade Brasileira de Computação - SBC, 2020. http://dx.doi.org/10.5753/sbcas.2020.11525.
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The COVID-19 pandemics will impact the demand for healthcare severely. It is essential to continually monitor and predict the expected number of new cases for each country. We explored the use of econometrics, machine learning, and ensemble models to predict the number of new cases per day for Brazil, China, Italy, and South Korea. These models can be used to make predictions in the short term, complementing the epidemiological models. Our main findings were: (i) there is no single best model for all countries; (ii) ensembles can, in some instances, improve the results of individual models; and (iii) the ML models had worse results due to the lack of data.
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Wang, Wenjia. "Some fundamental issues in ensemble methods." In 2008 IEEE International Joint Conference on Neural Networks (IJCNN 2008 - Hong Kong). IEEE, 2008. http://dx.doi.org/10.1109/ijcnn.2008.4634108.
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Chirikjian, Gregory S. "Parts Entropy, Symmetry and the Difficulty of Self-Replication." In ASME 2008 Dynamic Systems and Control Conference. ASMEDC, 2008. http://dx.doi.org/10.1115/dscc2008-2280.
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A self-replicating robot (SRR) is one that can identify and assemble spare parts into an exact functional copy of itself. An SRR that is able to identify and pick up parts that are randomly scattered in an environment without prior knowledge of their location would be more robust than one that requires parts to be positioned at exactly known locations. Therefore, the degree of disorder in the environment that an SRR is able to handle is in some sense a measure of how “powerful” it is. The entropy of the ensemble of all possible configurations of parts quantifies this concept. In this paper, various issues associated with computing the entropy of ensembles of configurations of parts are explored. The effect of part symmetries is analyzed. It is shown that both the design of parts and the evaluation of an SRR’s functionality can be influenced by the knowledge of part entropies.
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Jule, Alan, and Iryna Andriyanova. "Some Results on Update Complexity of a Linear Code Ensemble." In 2011 International Symposium on Network Coding (NetCod). IEEE, 2011. http://dx.doi.org/10.1109/isnetcod.2011.5979095.
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Xu, Mengnan, Dan Zeng, Zhichao Sheng, Zhonghao Zhang, and Chongbin Xu. "Some Results on Density Evolution of Nonbinary SC-LDPC Ensembles Over the BEC." In 2021 IEEE International Symposium on Information Theory (ISIT). IEEE, 2021. http://dx.doi.org/10.1109/isit45174.2021.9518021.
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Nguyen, Thanh Tan, Nan Ye, and Peter Bartlett. "Greedy Convex Ensemble." In Twenty-Ninth International Joint Conference on Artificial Intelligence and Seventeenth Pacific Rim International Conference on Artificial Intelligence {IJCAI-PRICAI-20}. California: International Joint Conferences on Artificial Intelligence Organization, 2020. http://dx.doi.org/10.24963/ijcai.2020/429.
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We consider learning a convex combination of basis models, and present some new theoretical and empirical results that demonstrate the effectiveness of a greedy approach. Theoretically, we first consider whether we can use linear, instead of convex, combinations, and obtain generalization results similar to existing ones for learning from a convex hull. We obtain a negative result that even the linear hull of very simple basis functions can have unbounded capacity, and is thus prone to overfitting; on the other hand, convex hulls are still rich but have bounded capacities. Secondly, we obtain a generalization bound for a general class of Lipschitz loss functions. Empirically, we first discuss how a convex combination can be greedily learned with early stopping, and how a convex combination can be non-greedily learned when the number of basis models is known a priori. Our experiments suggest that the greedy scheme is competitive with or better than several baselines, including boosting and random forests. The greedy algorithm requires little effort in hyper-parameter tuning, and also seems able to adapt to the underlying complexity of the problem. Our code is available at https://github.com/tan1889/gce.
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Vasilchuk, Vladimir. "Asymptotic distribution of the spectrum of some symmetric polynomials of unitary invariant random matrix ensembles." In 2016 Days on Diffraction (DD). IEEE, 2016. http://dx.doi.org/10.1109/dd.2016.7756889.
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Wen, Xian-Huan, and Wen H. Chen. "Some Practical Issues on Real-Time Reservoir Model Updating Using Ensemble Kalman Filter." In International Petroleum Technology Conference. International Petroleum Technology Conference, 2005. http://dx.doi.org/10.2523/11024-ms.
Full textReports on the topic "Ensembles somme"
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Pedersen, Gjertrud. Symphonies Reframed. Norges Musikkhøgskole, August 2018. http://dx.doi.org/10.22501/nmh-ar.481294.
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Symphonies Reframed recreates symphonies as chamber music. The project aims to capture the features that are unique for chamber music, at the juncture between the “soloistic small” and the “orchestral large”. A new ensemble model, the “triharmonic ensemble” with 7-9 musicians, has been created to serve this purpose. By choosing this size range, we are looking to facilitate group interplay without the need of a conductor. We also want to facilitate a richness of sound colours by involving piano, strings and winds. The exact combination of instruments is chosen in accordance with the features of the original score. The ensemble setup may take two forms: nonet with piano, wind quartet and string quartet (with double bass) or septet with piano, wind trio and string trio. As a group, these instruments have a rich tonal range with continuous and partly overlapping registers. This paper will illuminate three core questions: What artistic features emerge when changing from large orchestral structures to mid-sized chamber groups? How do the performers reflect on their musical roles in the chamber ensemble? What educational value might the reframing unfold? Since its inception in 2014, the project has evolved to include works with vocal, choral and soloistic parts, as well as sonata literature. Ensembles of students and professors have rehearsed, interpreted and performed our transcriptions of works by Brahms, Schumann and Mozart. We have also carried out interviews and critical discussions with the students, on their experiences of the concrete projects and on their reflections on own learning processes in general. Chamber ensembles and orchestras are exponents of different original repertoire. The difference in artistic output thus hinges upon both ensemble structure and the composition at hand. Symphonies Reframed seeks to enable an assessment of the qualities that are specific to the performing corpus and not beholden to any particular piece of music. Our transcriptions have enabled comparisons and reflections, using original compositions as a reference point. Some of our ensemble musicians have had first-hand experience with performing the original works as well. Others have encountered the works for the first time through our productions. This has enabled a multi-angled approach to the three central themes of our research. This text is produced in 2018.