87 research outputs found
Discrete Elastic Inner Vector Spaces with Application in Time Series and Sequence Mining
This paper proposes a framework dedicated to the construction of what we call
discrete elastic inner product allowing one to embed sets of non-uniformly
sampled multivariate time series or sequences of varying lengths into inner
product space structures. This framework is based on a recursive definition
that covers the case of multiple embedded time elastic dimensions. We prove
that such inner products exist in our general framework and show how a simple
instance of this inner product class operates on some prospective applications,
while generalizing the Euclidean inner product. Classification experimentations
on time series and symbolic sequences datasets demonstrate the benefits that we
can expect by embedding time series or sequences into elastic inner spaces
rather than into classical Euclidean spaces. These experiments show good
accuracy when compared to the euclidean distance or even dynamic programming
algorithms while maintaining a linear algorithmic complexity at exploitation
stage, although a quadratic indexing phase beforehand is required.Comment: arXiv admin note: substantial text overlap with arXiv:1101.431
CritĂšres d'Ă©valuation pour les interfaces des systĂšmes de recherche d'information
ISBN 2-9520326-6-1La visualisation (ou restitution) des résultats d'une recherche est une étape essentielle dans tout processus de recherche d'information. En effet, les interfaces utilisateur d'information servent de lien entre les utilisateurs et les systÚmes de recherche d'information, et permettent donc de donner un « sens » aux résultats pour les utilisateurs. Face à l'importance que prend la visualisation des résultats, de nombreuses interfaces (textuelles, 2D ou 3D) ont été proposées depuis une dizaine d'années. Cependant, bien que des évaluations aient été proposées, elles sont trop rares et peu interprétables (et comparables) du fait de la trop grande hétérogénéité des systÚmes et de l'absence d'un cadre strict d'évaluation. Dans cet article, nous proposons donc de définir un ensemble de critÚres dans le but d'évaluer et de comparer ces interfaces
Ăvaluation des Interfaces Utilisateur d'Information
Tout processus de recherche d'information (RI) n'a de sens aux yeux des utilisateurs qu'à travers l'ultime étape qui consiste à visualiser les résultats. L'importance que prend la visualisation (ou restitution) des résultats est à l'origine des nombreuses propositions d'interfaces, qu'elles soient textuelles, 2D ou 3D. Si des évaluations de certaines de ces interfaces ont été proposées, aucune comparaison n'a réellement été réalisée dans ce contexte faute de contraintes sur ces interfaces et de critÚres de comparaison relatifs à la tùche de RI. Dans cet article, nous proposons d'introduire des pistes d'évaluation afin d'aboutir à un cadre expérimental permettant l'évaluation et ainsi la comparai-son des Interfaces Utilisateur d'Information
Spiral Walk on Triangular Meshes : Adaptive Replication in Data P2P Networks
We introduce a decentralized replication strategy for peer-to-peer file
exchange based on exhaustive exploration of the neighborhood of any node in the
network. The replication scheme lets the replicas evenly populate the network
mesh, while regulating the total number of replicas at the same time. This is
achieved by self adaptation to entering or leaving of nodes. Exhaustive
exploration is achieved by a spiral walk algorithm that generates a number of
messages linearly proportional to the number of visited nodes. It requires a
dedicated topology (a triangular mesh on a closed surface). We introduce
protocols for node connection and departure that maintain the triangular mesh
at low computational and bandwidth cost. Search efficiency is increased using a
mechanism based on dynamically allocated super peers. We conclude with a
discussion on experimental validation results
Représentations Temps-Fréquence de la classe de puissance basées sur l'invariant océanique
National audienceEn acoustique sous marine Ultra Basse FrĂ©quence (UBF < 200 Hz), un environnement ocĂ©anique petit fond (D < 200 m) se comporte comme un guide d'onde dispersif, dans lequel de nombreuses applications (inversion gĂ©oacoustique, localisation de source) considĂšrent la propagation de sources impulsionnelles (canons Ă air, explosions, baleines, ...). Comment obtenir une reprĂ©sentation temps-frĂ©quence correcte des signaux correspondants? Ces signaux sont multicomposantes, chaque composante possĂšde un retard de groupe non-linĂ©aire et il n'existe pas de lien direct entre les diffĂ©rentes composantes. Cependant, le retard de groupe de chaque composante peut ĂȘtre approximĂ© par une fonction puissance en f puissance (â1/Beta) , oĂč "Beta"est l'invariant ocĂ©anique (un scalaire qui rĂ©sume la dispersion globale dans le guide d'onde). On peut alors dĂ©finir une Beta-classe de reprĂ©sentations temps-frĂ©quence adaptĂ©es au signal reçu. La mĂ©thode est appliquĂ©e avec succĂšs sur des donnĂ©es rĂ©elles marines et permet une bonne reprĂ©sentation temps-frĂ©quence des signaux considĂ©rĂ©s. Elle est robuste au bruit naturel de l'environnement marin, et Ă une erreur dans le choix de "Beta
LNA: Fast Protein Classification Using A Laplacian Characterization of Tertiary Structure
International audienceIn the last two decades, a lot of protein 3D shapes have been discovered, characterized and made available thanks to the Protein Data Bank (PDB), that is nevertheless growing very quickly. New scalable methods are thus urgently required to search through the PDB efficiently. We present in this paper an approach entitled LNA (Laplacian Norm Alignment) that performs structural comparison of two proteins with dynamic programming algorithms. This is achieved by characterizing each residue in the protein with scalar features. The feature values are calculated using a Laplacian operator applied on the graph corresponding to the adjacency matrix of the residues. The weighted Laplacian operator we use estimates at various scales local deformations of the topology where each residue is located. On some benchmarks widely shared by the community we obtain qualitatively similar results compared to other competing approaches, but with an algorithm one or two order of magnitudes faster. 180,000 protein comparisons can be done within 1 seconds with a single recent GPU, which makes our algorithm very scalable and suitable for real-time database querying across the Web
SystÚme de recherche de méthodes Java basé sur leur signature
L'objectif de cet article est de proposer une démarche permettant de mettre en place un moteur de recherche de méthodes au sein d'un langage de programmation. Un tel outil s'avÚre particuliÚrement utile aux développeurs. Des solutions ont déjà été proposées mais elles sont pour la plupart basées sur une recherche textuelle, c'est-à -dire uniquement basées sur le contenu textuel de la description des différentes méthodes. Nous proposons dans cet article une nouvelle approche basée sur la signature des méthodes. Le langage utilisé tout au long de cet article est le langage Java
Meaning Metaphor for Visualizing Search Results
ISBN 0-7695-2397-8While searching the Web, the user is often confronted by a great number of results, generally sorted by their rank. These results are then displayed as a succession of ordered lists. Facing the limits of this approach, we propose a prototype to explore new organizations and presentations of search results, as well as new types of interactions with the results in order to make their exploration more intuitive and efficient. The main topic of this paper is the processing of the results coming from an information retrieval system. Although the relevance depends on the result quality, the effectiveness of the result processing represents an alternative way to improve the relevance for the user. Given the current expectations, this processing is composed by an organization step and a visualization step. Then the proposed prototype organizes the results according to their meaning using a Kohonen self-organizing map, and also visualizes them in a 3D scene to increase the representation space. The 3D metaphor proposed here is a city
Detection of a close supernova gravitational wave burst in a network of interferometers, neutrino and optical detectors
Trying to detect the gravitational wave (GW) signal emitted by a type II
supernova is a main challenge for the GW community. Indeed, the corresponding
waveform is not accurately modeled as the supernova physics is very complex; in
addition, all the existing numerical simulations agree on the weakness of the
GW emission, thus restraining the number of sources potentially detectable.
Consequently, triggering the GW signal with a confidence level high enough to
conclude directly to a detection is very difficult, even with the use of a
network of interferometric detectors. On the other hand, one can hope to take
benefit from the neutrino and optical emissions associated to the supernova
explosion, in order to discover and study GW radiation in an event already
detected independently. This article aims at presenting some realistic
scenarios for the search of the supernova GW bursts, based on the present
knowledge of the emitted signals and on the results of network data analysis
simulations. Both the direct search and the confirmation of the supernova event
are considered. In addition, some physical studies following the discovery of a
supernova GW emission are also mentioned: from the absolute neutrino mass to
the supernova physics or the black hole signature, the potential spectrum of
discoveries is wide.Comment: Revised version, accepted for publication in Astroparticle Physic
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