Laboratoire dInformatique

Saint-Étienne-de-Baïgorry, France

Laboratoire dInformatique

Saint-Étienne-de-Baïgorry, France
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Jarraya H.,Computer Vision Center | Luqman M.M.,University of La Rochelle | Ramel J.-Y.,Laboratoire Dinformatique
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2017

The graphics recognition research community has been employing graphs, in one form or another, for at-least the last three decades. These data-structures have proven to be the most powerful representations for encoding the structural information of underlying data, for further processing. However, there is still a lack of tools and methods which could be employed to process these useful data-structures in an efficient manner. Graph embedding provides a solution for this problem. In this paper we present an improvement of the Fuzzy Multilevel Graph Embedding (FMGE) technique, by adding new topological node features, named Morgan Index. The experimental results on GREC, Mutagenicity and Fingerprint datasets from IAM graph database, illustrate improved results for the graph classification and graph clustering problems. © Springer International Publishing AG 2017.

Hanyf Y.,Chouaïb Doukkali University | Silkan H.,Laboratoire dInformatique
ACM International Conference Proceeding Series | Year: 2017

Due to the development of images data production and use, the size of images databases is exponentially increased recently. Consequently, the similarity search time in images databases becoming a severe problem which affects the exploitation of image data. In this paper, we address the problem of reducing the similarity search cost in large, high-dimensional and dynamic image datasets; we propose a coherent improvement of the D-index method, the amelioration aims to reduce the number of distances computed during a query search. The method is tested over a 112 dimensional color images databases, the experiences show that the proposed D-index version has proved a good performance in comparison with the classical D-index. © 2017 Association for Computing Machinery.

Bonamy M.,Laboratoire dInformatique | Johnson M.,Durham University | Lignos I.,Durham University | Patel V.,Durham University | Paulusma D.,Durham University
Journal of Combinatorial Optimization | Year: 2014

A k-colouring of a graph G=(V,E) is a mapping c:V→{1,2,.,k} such that c(u)≠c(v) whenever uv is an edge. The reconfiguration graph of the k-colourings of G contains as its vertex set the k-colourings of G, and two colourings are joined by an edge if they differ in colour on just one vertex of G. We introduce a class of k-colourable graphs, which we call k-colour-dense graphs. We show that for each k-colour-dense graph G, the reconfiguration graph of the ℓ-colourings of G is connected and has diameter O(|V|2), for all ℓ≥k+1. We show that this graph class contains the k-colourable chordal graphs and that it contains all chordal bipartite graphs when k=2. Moreover, we prove that for each k≥2 there is a k-colourable chordal graph G whose reconfiguration graph of the (k+1)-colourings has diameter Θ(|V|2). © 2012 Springer Science+Business Media, LLC.

Romero J.G.,Laboratoire dInformatique | Ortega R.,Supelec
Automatica | Year: 2015

A globally exponentially stable speed observer for mechanical systems was recently reported in the literature, under the assumptions of known (or no) Coulomb friction and no disturbances. In this note we propose and adaptive version of this observer, which is robust vis-à-vis constant disturbances. Moreover, we propose a new globally convergent speed observer that, besides rejecting the disturbances, estimates some unknown friction coefficients for a class of mechanical systems that contains several practical examples. © 2015 Elsevier Ltd.

Destercke S.,CIRAD - Agricultural Research for Development | Strauss O.,Laboratoire dInformatique
Soft Computing | Year: 2012

Selecting a particular kernel to filter a given digital signal can be a difficult task. One solution to solve this difficulty is to filter with multiple kernels. However, this solution can be computationally costly. Using the fact that most kernels used for low-pass signal filtering can be assimilated to probability distributions (or linear combinations of probability distributions), we propose to model sets of kernels by convex sets of probabilities. In particular, we use specific representations that allow us to perform a robustness analysis without added computational costs. The result of this analysis is an interval-valued filtered signal. Among such representations are possibility distributions, from which have been defined maxitive kernels. However, one drawback of maxitive kernels is their limited expressiveness. In this paper, we extend this approach by considering another representation of convex sets of probabilities, namely clouds, from which we define cloudy kernels. We show that cloudy kernels are able to represent sets of kernels whose bandwidth is upper and lower bounded, and can therefore be used as a good trade-off between the classical and the maxitive approach, avoiding some of their respective shortcomings without making computations prohibitive. Finally, the benefits of using cloudy filters is demonstrated through some experiments. © 2011 Springer-Verlag.

Hassoune I.,Laboratoire dInformatique | Flandre D.,Catholic University of Louvain | O'Connor I.,École Centrale Lyon | Legat J.-D.,Catholic University of Louvain
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2010

In this paper, we first propose a new structure of a hybrid full adder, namely, the branch-based logic and pass-transistor (BBL-PT) cell, which we implemented by combining branch-based logic and pass-transistor logic. Evolution of the proposed cell from its original version to an ultralow-power (ULP) cell is described. Quantitative comparisons of the optimized version, namely, the ULP full adder (ULPFA), are carried out versus the BBL-PT full adder and its counterparts in two well-known and commonly used logic styles, i.e., conventional static CMOS logic and complementary pass logic (CPL), in a 0.13- μm PD SOI CMOS with a supply voltage of 1.2 V, demonstrating power delay product (PDP) and static power performance that are more than four times better than CPL design. This could lead to tremendous benefit for multiplier application. The implementation of an 8-bit ripple carry adder based on the ULPFA is finally described, and comparisons between adders based on full adders from the prior art and our ULPFA version demonstrate that our development outperforms the static CMOS and the CPL full adders, particularly in terms of power consumption and PDP by at least a factor of two. © 2006 IEEE.

Riehl N.,Tecnalia | Gouttefarde M.,Laboratoire dInformatique | Baradat C.,Tecnalia | Pierrot F.,Laboratoire dInformatique
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2010

Generally, the cables of a parallel cable-driven robot are considered to be massless and inextensible. These two characteristics cannot be neglected anymore for large dimension mechanisms in order to obtain good positioning accuracy. A well-known model which describes the profile of a cable under the action of its own weight allows us to take mass and elasticity into account. When designing a robot, and choosing actuator and cable characteristics, a calculation of maximal tension has to be done. However, because cable mass has a significant effect on cable tensions, a model including cable mass has to be included in the design step. This paper proposes two methods to determine the appropriate cable and hence the maximal tensions in the cables. Applied to a large dimension robot, taking cable mass into account is proved to be necessary in comparison with an equivalent method based on the massless cable modeling. In this paper, only moving platform static equilibria are considered (slow enough motions). ©2010 IEEE.

Mauris G.,Laboratoire dInformatique
IEEE Transactions on Instrumentation and Measurement | Year: 2010

At the application level, it is important to be able to define the measurement result as an interval that will contain an important part of the distribution of the measured values, that is, a coverage interval. This practice acknowledged by the International Organization for Standardization (ISO) Guide is a major shift from the probabilistic representation. It can be viewed as a probability/possibility transformation by viewing possibility distributions as encoding coverage intervals. In this paper, we extend previous works on unimodal distributions by proposing a possibility representation of bimodal probability distributions. Indeed, U-shaped distributions or Gaussian mixture distribution are not very rare in the context of physical measurements. Some elements to further propagate such bimodal possibility distributions are also exposed. The proposed method is applied to the case of three independent or positively correlated C-grade resistors in series and compared with the Guide to the Expression of Uncertainty in Measurement (GUM) and Monte Carlo methods. © 2009 IEEE.

Hassan S.,Laboratoire dInformatique
2015 5th International Conference on Information and Communication Technology and Accessibility, ICTA 2015 | Year: 2015

In this paper we present a new fast method for 3D objects indexing and retrieval based on two-dimensional (2-D) views. The set of views are automatically generated around OX, OY and OZ by rotating each 3D object of database through 360° with taking views at pose intervals of 45°, given 24 images per object. The obtained views are afterward described by two descriptors: Angular Radial transform adopted by MPEG-7 and Fourier descriptor. The similarity of 3D objects is calculated as a linear combination of euclidian metrics. In order to lower the cost of search, we propose to apply a mapping from metric space to vector space of 3D descriptors by using a contractive function. We have implemented an application for indexing and retrieval of 3D objects by using Princeton 3D Shape Benchmark database. The performance of our retrieval system was measured in terms of recall and precision and Computation efficiency. The obtained results prove the effectiveness of proposed method and its superiority over automatic selection based on Curvature Scale Space. © 2015 IEEE.

Gouttefarde M.,Laboratoire dInformatique | Collard J.-F.,Laboratoire dInformatique | Riehl N.,Tecnalia | Baradat C.,Tecnalia
Proceedings - IEEE International Conference on Robotics and Automation | Year: 2012

This paper introduces a new simplified static analysis of parallel robots driven by inextensible cables of non-negligible mass. It is based on a known hefty cable static modeling which seems to have been overlooked in previous works on parallel cable-driven robots. This cable modeling is obtained from a well-known sagging cable modeling, known as the catenary, by assuming that cable sag is relatively small. The use of the catenary has been shown to lead to a non-linear set of equations describing the kinetostatic behavior of parallel robots driven by cables of non-negligible mass. On the contrary, the proposed simplified static analysis yields a linear relationship between (components of) the forces in the cables and the external wrench applied to the robot mobile platform. As a consequence, by means of the simplified static analysis, useful wrench-based analysis and design techniques devised for parallel robots driven by massless cables can now be extended to cases in which cable mass is to be accounted for. © 2012 IEEE.

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