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Reims, France

Buchoud E.,EdF | Mars J.,CNRS GIPSA Laboratory | Vrabie V.,CReSTIC | D'Urso G.,EdF | And 3 more authors.
76th European Association of Geoscientists and Engineers Conference and Exhibition 2014: Experience the Energy - Incorporating SPE EUROPEC 2014 | Year: 2014

To ensure stability and durability of engineering structure in natural soil, optical fiber sensors have gained interest over last decade. In addition to conventional geophysical sensors, Brillouin spectra based sensor enables to perform distributed strain measurement. Its algorithm performs a strain measurement with a 40cm spatial sampling over several kilometers. The monitoring of engineering installations needs a centimeter spatial sampling and a better strain accuracy. Previous works highlighted that the industrialized algorithm has great limitation for the exploitation of the local information contained into Brillouin spectra. Indeed, based on its asymmetry and broadening, it is possible to estimate local Brillouin frequencies with a better strain accuracy. We propose here to apply a parametric inverse method using L-curve criterion to estimate the strain with a 5cm spatial sampling. To validate this method, a one-to-one scale experiment has been implemented by optical fiber cable at several depths. Comparing the distributed strain provided by the Brillouin based sensor and our algorithm with a reference strain sensor, the proposed algorithm successfully fulfills the combination of a 5cm spatial sampling over kilometers and a high strain accuracy. Source

Quang K.N.,Hanoi University of Science and Technology | Nguyen V.D.,Hanoi University of Science and Technology | Nguyer T.D.,Hanoi University of Science and Technology | Nguyer T.H.,Hanoi University of Science and Technology | Gelle G.,CReSTIC
2013 International Conference on Computing, Management and Telecommunications, ComManTel 2013 | Year: 2013

In this paper, a new cross layer design of MAC and Routing protocol for OFDMA-based Multi-hop Ad-hoc Networks is proposed. In wireless network, when a route is established, the radio resource allocation problems at MAC layer may decrease the end to end performance proportionally with the length of each route. The contention at MAC layer may causes routing protocol to respond by finding new routes and routing table updates. The cross layer design allows layers to exchange state information in order to solve the problem and obtain higher performance. The proposed cross layer design of MAC and Routing protocol based the dynamic Sub-channel Assignment Algorithm in [4] to ensure the performance of ad-hoc and multi-hop networks is significantly improved. © 2013 IEEE. Source

Seghir Z.A.,University of Khenchela | Hachouf F.,Automatic and Robotic Laboratory | Morain-Nicolier F.,CReSTIC
2013 IEEE 2nd International Conference on Image Information Processing, IEEE ICIIP 2013 | Year: 2013

In this paper, an objective assessment of image quality is considered. Principal human eyes function is to take out the region or edge information from the vision field. Based on this function, a new no-reference image quality measure is proposed. First, we identify the image edges using canny operator. Secondly, we compute the absolute difference mask. Then, the two operators are used to compute the entire metric. Experimental results show the efficiency of the suggested measure. © 2013 IEEE. Source

Kopriva I.,Ruder Boskovic Institute | Nuzillard D.,CReSTIC
International Geoscience and Remote Sensing Symposium (IGARSS) | Year: 2015

Estimation of pure spectral signatures, called endmembers, is a key step in hyperspectral image (HI) analysis. We propose endmembers estimation method that uses Gabor Filter Banks (GFBs) to filter HI into set of HIs with different resolutions and orientations. Afterwards, set of approximate pure pixels is identified from each filtered HI by means of directivity based criterion. Hierarchical clustering is used to estimate candidate endmembers from sets of approximate pure pixels. Final estimate of endmembers is obtained after annotation of candidate endmembers with library of pure spectral signatures. Thereby, candidate with the smallest angular deviation with respect to corresponding pure spectra is selected as endmember estimate. Proposed method is compared favorably with five endmembers estimation methods using well-understood experimental AVIRIS Cuprite Nevada dataset. © 2015 IEEE. Source

Couturier J.-F.,CReSTIC | Letourneur R.,CNRS Orleans Fundamental Informatics Laboratory | Liedloff M.,CNRS Orleans Fundamental Informatics Laboratory
Theoretical Computer Science | Year: 2015

A dominating set in a graph is a subset of vertices such that each vertex is either in the dominating set or adjacent to some vertex in the dominating set. It is known that graphs have at most O(1.7159n) minimal dominating sets. In this paper, we establish upper bounds on this maximum number of minimal dominating sets for split graphs, cobipartite graphs and interval graphs. For each of these graph classes, we provide an algorithm to enumerate them. For split and interval graphs, we show that the number of minimal dominating sets is at most 3n/3≈1.4423n, which is the best possible bound. This settles a conjecture by Couturier et al. (SOFSEM 2012, [1]). For cobipartite graphs, we lower the O(1.5875n) upper bound from Couturier et al. to O(1.4511n). © 2014 Elsevier B.V. Source

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