Search results for " algorithms"
showing 10 items of 612 documents
Overlapping community detection versus ground-truth in AMAZON co-purchasing network
2015
International audience; Objective evaluation of community detection algorithms is a strategic issue. Indeed, we need to verify that the communities identified are actually the good ones. Moreover, it is necessary to compare results between two distinct algorithms to determine which is most effective. Classically, validations rely on clustering comparison measures or on quality metrics. Although, various traditional performance measures are used extensively. It appears very clearly that they cannot distinguish community structures with different topological properties. It is therefore necessary to propose an alternative methodology more sensitive to the community structure variations in orde…
Bords d'une surface médiane : Identifications et applications
2014
National audience; Un squelette d'une forme fermée est une structure mince, centrée dans cette forme, décrivant sa topologie et sa géométrie. Les squelettes permettent de développer des applications interactives en synthèse d'images~: l'utilisateur peut manipuler intuitivement des formes en modifiant leurs squelettes. Parmi toutes les formulations de squelettes, nous nous intéressons en particulier à la surface médiane. Ses éléments, nommés atomes, sont les sphères maximales intérieures à la forme décrite. Les positions des atomes sont organisées en courbes et surfaces, qui composent la structure squelettale. Cette structure peut être d'une grande aide pour manipuler une forme. Cependant, e…
WSN localization scheme based on Received Signal Strength Indicator (RSSI) for ZigBee Networks
2015
International audience; Wireless Sensor Networks (WSNs) have diverse application domains such as smart home, smart care, industrial, etc. We present a WSN system based on the ZigBee technology (IEEE 802.15.4) in Smart Home. In our paper we interest to ZigBee protocol is often used in medical Rehabilitation, which is a relatively new concept involving wireless transmission of data from the sensors attached to a patient to a distant monitoring station. There is no standardized topology managing the current networks, therefore, we will compare and evaluate the performance the mobility of nodes for star topologies in different scenarios to determine which is the most suitable in a typical hospi…
Spectral approach to D-bar problems
2017
We present the first numerical approach to D-bar problems having spectral convergence for real analytic, rapidly decreasing potentials. The proposed method starts from a formulation of the problem in terms of an integral equation that is numerically solved with Fourier techniques. The singular integrand is regularized analytically. The resulting integral equation is approximated via a discrete system that is solved with Krylov methods. As an example, the D-bar problem for the Davey-Stewartson II equations is considered. The result is used to test direct numerical solutions of the PDE.© 2017 Wiley Periodicals, Inc.
Application of LSTM architectures for next frame forecasting in Sentinel-1 images time series
2020
L'analyse prédictive permet d'estimer les tendances des évènements futurs. De nos jours, les algorithmes Deep Learning permettent de faire de bonnes prédictions. Cependant, pour chaque type de problème donné, il est nécessaire de choisir l'architecture optimale. Dans cet article, les modèles Stack-LSTM, CNN-LSTM et ConvLSTM sont appliqués à une série temporelle d'images radar sentinel-1, le but étant de prédire la prochaine occurrence dans une séquence. Les résultats expérimentaux évalués à l'aide des indicateurs de performance tels que le RMSE et le MAE, le temps de traitement et l'index de similarité SSIM, montrent que chacune des trois architectures peut produire de bons résultats en fon…
FOWLA, A Federated Architecture for Ontologies.
2015
International audience; The progress of information and communication technologies has greatly increased the quantity of data to process. Thus, managing data heterogeneity is a problem nowadays. In the 1980s, the concept of a Federated Database Architecture (FDBA) was introduced as a collection of components to unite loosely coupled federation. Semantic web technologies mitigate the data heterogeneity problem, however due to the data structure heterogeneity the integration of several ontologies is still a complex task. For tackling this problem, we propose a loosely coupled federated ontology architecture (FOWLA). Our approach allows the coexistence of various ontologies sharing common data…
Drivers-Inspired Ants for Solving the Vehicle Routing Problem with Time Windows
2016
International audience; In our study, we develop a method that merges two information sources within ants colony optimization heuristic. Namely artificial ants which occurs for short term optimization and transporter's vehicles that occurs in long term and continuous optimization toward solving the real-world vehicle routing problem. This study is supported by a transporter (Upsilon) of the region of l'Yonne in France and a transport and logistics software development company (Tedies). Our method suits for transporters that use human planners to make decisions about their tours and intending to move to computer planners without drastically upsetting the drivers habits. Hence, the pledge of …
Automatic ontology-based User Profile Learning from heterogeneous Web Resources in a Big Data Context
2013
International audience; The Web has developed to the biggest source of information and entertainment in the world. By its size, its adaptability and flexibility, it challenged our current paradigms on information sharing in several areas. By offering everybody the opportunity to release own contents in a fast and cheap way, the Web already led to a revolution of the traditional publishing world and just now, it commences to change the perspective on advertisements. With the possibility to adapt the contents displayed on a page dynamically based on the viewer's context, campaigns launched to target rough customer groups will become an element of the past. However, this new ecosystem, that re…
Semantics - Supportive Element for the Cooperative Evaluation of Geographical and Historical Information
2013
International audience; The emergence of the Semantic Web and its underlying knowledge technologies has brought changes in data han- dling. Transferring expert knowledge to machines through knowledge formalization provides us the required support in managing huge datasets like the information in the World Wide Web. In the field of geospatial technology semantic technologies not only entail the capability to achieve higher degree of data integration but also infer semantics to discover new and hidden knowledge. This is of particular interest in the field of archaeology, where complex interrelations among heterogeneous datasets exist. Although researches on seman- tics are active areas in geo…
Semantic and Multi-scale BIM/CIM/LIM
2019
Compliance checking for building models, cities and territories involve formalizing a set of model schema knowledge and constraint. The objective of our study is to propose: an information model to federate heterogeneous data sources describing an urban area (building and building environment) along with a method for formally specifying of urban rules. The overall goal we pursue is to be able to query and to verify data against different regulations and/or requirements. The purpose of this article is to describe our approach for interoperability among different data sources (e.g. IFC, CityGML) thus creating a consistent description of an urban area.