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1,354 results on '"SIMON, LAURENT"'

57. A general framework for online audio source separation

Author

Simon, Laurent S. R. and Vincent, Emmanuel

Subjects
Computer Science - Sound
Abstract

We consider the problem of online audio source separation. Existing algorithms adopt either a sliding block approach or a stochastic gradient approach, which is faster but less accurate. Also, they rely either on spatial cues or on spectral cues and cannot separate certain mixtures. In this paper, we design a general online audio source separation framework that combines both approaches and both types of cues. The model parameters are estimated in the Maximum Likelihood (ML) sense using a Generalised Expectation Maximisation (GEM) algorithm with multiplicative updates. The separation performance is evaluated as a function of the block size and the step size and compared to that of an offline algorithm., Comment: International conference on Latente Variable Analysis and Signal Separation (2012)

Published
2011

58. Dirac point metamorphosis from third-neighbor couplings in graphene

Author

Bena, Cristina and Simon, Laurent

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

We study the band structure and the density of states of graphene in the presence of a next-to-nearest-neighbor coupling (N2) and a third-nearest-neighbor coupling (N3). We show that for values of N3 larger or equal to 1/3 of the value of the nearest-neighbor hopping (NN), extra Dirac points appear in the spectrum. If N3 is exactly equal to 1/3 NN, the new Dirac points are localized at the M points of the Brillouin zone and are hybrid: the electrons have a linear dispersion along the GammaM direction and a quadratic dispersion along the perpendicular direction MK. For larger values of N3 the new points have a linear dispersion, and are situated along the MK line. For a value of N3 equal to 1/2 NN, these points merge with the Dirac cones at the K points, yielding a gapless quadratic dispersion around K, while for larger values each quadratic point at K splits again into four Dirac points. The effects of changing the N2 coupling are not so dramatic. We calculate the density of states and we show that increasing the N3 coupling lowers the energy of the Van Hove singularities, and when N3 is larger than 1/3 NN the Van Hove singularities split in two, giving rise to extra singularities at low energies., Comment: 13 pages, 10 figures

Published
2010
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59. Laser Doppler Velocimetry for Joint Measurements of Acoustic and Mean Flow Velocities : LMS-based Algorithm and CRB Calculation

Author

Simon, Laurent, Richoux, Olivier, Degroot, Anne, and Lionet, Louis

Subjects
Physics - Classical Physics
Abstract

This paper presents a least mean square (LMS) algorithm for the joint estimation of acoustic and mean flow velocities from laser doppler velocimetry (LDV) measurements. The usual algorithms used for measuring with LDV purely acoustic velocity or mean flow velocity may not be used when the acoustic field is disturbed by a mean flow component. The LMS-based algorithm allows accurate estimations of both acoustic and mean flow velocities. The Cram\'er-Rao bound (CRB) of the associated problem is determined. The variance of the estimators of both acoustic and mean flow velocities is also given. Simulation results of this algorithm are compared with the CRB and the comparison leads to validate this estimator.

Published
2009
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67. Biotic and abiotic drivers of aquatic plant communities in shallow pools and wallows on the sub-Antarctic Iles Kerguelen

Author

Douce, Pauline, Mermillod‐blondin, Florian, Simon, Laurent, Dolédec, Sylvain, Eymar‐dauphin, Pauline, Renault, David, Sulmon, Cécile, Vallier, Félix, Bittebiere, Anne-Kristel, Équipe 1 - Biodiversité et Adaptation dans les Hydrosystèmes (BAH), Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École Nationale des Travaux Publics de l'État (ENTPE)-Centre National de la Recherche Scientifique (CNRS), Équipe 3 - Écologie, Évolution, Écosystemes Souterrains (E3S), Ecosystèmes, biodiversité, évolution [Rennes] (ECOBIO), Université de Rennes (UR)-Institut Ecologie et Environnement (INEE), Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Rennes (OSUR), and Université de Rennes (UR)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Rennes 2 (UR2)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Habitat, Plant community structure, Spatio-temporal variability, Seasonality, [SDE.BE]Environmental Sciences/Biodiversity and Ecology, [SDV.BV.BOT]Life Sciences [q-bio]/Vegetal Biology/Botanics, Aquatic plants, Ponds, General Agricultural and Biological Sciences
Abstract

International audience; In the sub-Antarctic region, climate change is particularly rapid, while their freshwater ecosystems, such as ponds, host plant species with limited spatial distributions. These particular systems and their plant communities remain however poorly known and the context of their changing habitat calls for deeper insights into these systems. We performed an extensive survey of 45 ponds over three locations of the Iles Kerguelen during the winter and summer seasons of two years, which included the measurement of 12 abiotic parameters and the assessment of the plant community composition. Overall, our results showed that Iles Kerguelen ponds are shallow freshwater ecosystems harbouring species-poor plant communities with high even- ness, of which structure did not vary among the sampled locations. Three different habitats were identified among ponds in relation with nutrient supply by marine animals, which ultimately influenced plant community structure and cover. We highlight that these habitats are mostly determined by water depth, nutrients, and temperature (mean and variance). Present plant community composition was more strongly correlated with plant community composition in the previous year than with abiotic conditions. Overall, this study provides new knowledge on the aquatic plant communities and the functioning of Iles Kerguelen freshwater ecosystems, which can serve as a basis for future studies dealing with the impact of climate change in the sub-Antarctic region.

Published
2023

68. On the Community Structure of Bounded Model Checking SAT Problems

Author

Baud-Berthier, Guillaume, Giráldez-Cru, Jesús, Simon, Laurent, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Gaspers, Serge, editor, and Walsh, Toby, editor

Published
2017
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72. Development of multichannel recording and reproduction techniques based on auditory perceptual cues

Author

Simon, Laurent

Subjects
780
Abstract

In order to capture and reproduce sound all around the listener in a perceptually realistic way, a recording technique (microphone layout) and a reproduction system (loudspeaker layout) capable of accurate 360° imaging are required. In order to develop the reproduction system, binaural and loudspeaker-based localisation cues were investigated in a literature review. The necessary loudspeaker-based localisation cues to manipulate the location of a sound image were analysed, and these showed that the common 5.1 surround sound loudspeaker arrangement could produce stable images to the front of the listener but not to the side. An 8-channel loudspeaker configuration arranged as a regular octagon was therefore chosen based on attempting to recreate plausible interaural cues for all locations. The performance of this was compared to a 5.1 loudspeaker system in terms of localisation accuracy. It was shown that the octagonal loudspeaker configuration produces more stable and more accurate images all around the listener. The octagonal loudspeaker arrangement required new microphone techniques for optimum recording and reproduction. An overview of the current literature showed how localisation curves can be used to design microphone arrays, and the other physical and perceptual parameters that need to be considered in microphone array design. This showed that it is useful to derive localisation curves for the new loudspeaker configuration, as these can be used to optimise the microphone array's sound imaging accuracy. An experiment was therefore conducted to measure the localisation curves, and it showed that localisation curves are different for the loudspeaker pairs to the front, side or the rear of the listener. It also showed that to the side of the listener, interchannel time differences have little influence on the perceived location of the sound event. The derivation of these localisation curves enabled the development of a microphone array design tool that predicts the localisation profile of a microphone array as a function of its geometrical set-up and the directivities of the microphones. The predictions of this tool were evaluated by comparing sound image positions for recordings of ten sound sources with ten different microphone arrays. This showed that the error of prediction is small when the crosstalk due to the microphone array is low. A linear regression model was created and shown to reasonably model the error of prediction as a function of the crosstalk level and crosstalk delay.

Published
2011

76. Observation of defect density dependent elastic modulus of graphene

Author

Li, Hu, primary, Gürbüz, Emel, additional, Haldar, Soumyajyoti, additional, Hussain, Tanveer, additional, Zheng, Xiaoxiao, additional, Ye, Xiaoling, additional, Makumi, Sylvester Wambua, additional, Duan, Tianbo, additional, Jafri, Syed Hassan Mujtaba, additional, Daukiya, Lakshya, additional, Simon, Laurent, additional, Karton, Amir, additional, Sanyal, Biplab, additional, and Leifer, Klaus, additional

Published
2023
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78. Extreme Cases in SAT Problems

Author

Audemard, Gilles, Simon, Laurent, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Creignou, Nadia, editor, and Le Berre, Daniel, editor

Published
2016
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87. Estimation of volatile organic compound exposure concentrations and time to reach a specific dermal absorption using physiologically based pharmacokinetic modeling.

Author

Simon, Laurent

Subjects
*BIOLOGICAL models, *AIR pollution, *ABSORPTION, *ANIMAL experimentation, *ORGANIC compounds, *CONTINUING education units, *INDOOR air pollution, *SKIN physiology, *RATS, *RESEARCH funding, *ENVIRONMENTAL exposure
Abstract

A procedure was proposed to estimate dermal exposures based on a physiologically based pharmacokinetic (PBPK) model developed in rats. The study examined vapor concentrations ranging from 500 to 10,000 ppm for dibromomethane and 2,500 to 40,000 ppm for bromochloromethane. These concentrations were reconstructed based on chemical blood levels measured in 4 hr, with errors varying from 0.0% to 52.0%. The PBPK approach adequately predicted the blood concentrations and helped simulate contaminant transport through the stratum corneum and distribution in the body compartments. The proposed technique made it possible to estimate the skin absorption time (SAT) obtained from acute inhalation toxicity data. An inverse relationship exists between the SAT and exposure concentration. The method can be helpful in toxicology and risk assessment of hazardous volatile organic compounds. [ABSTRACT FROM AUTHOR]

Published
2024
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88. Using Community Structure to Detect Relevant Learnt Clauses

Author

Ansótegui, Carlos, Giráldez-Cru, Jesús, Levy, Jordi, Simon, Laurent, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Heule, Marijn, editor, and Weaver, Sean, editor

Published
2015
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91. Observation of defect density dependent elastic modulus of graphene

Author

Li, Hu, Gürbüz, Emel, Haldar, Soumyajyoti, Hussain, Tanveer, Zheng, Xiaoxiao, Ye, Xiaoling, Makumi, Sylvester Wambua, Duan, Tianbo, Jafri, Syed Hassan Mujtaba, Daukiya, Lakshya, Simon, Laurent, Karton, Amir, Sanyal, Biplab, Leifer, Klaus, Li, Hu, Gürbüz, Emel, Haldar, Soumyajyoti, Hussain, Tanveer, Zheng, Xiaoxiao, Ye, Xiaoling, Makumi, Sylvester Wambua, Duan, Tianbo, Jafri, Syed Hassan Mujtaba, Daukiya, Lakshya, Simon, Laurent, Karton, Amir, Sanyal, Biplab, and Leifer, Klaus

Abstract

The recent decade has witnessed a tremendous development of graphene applications in many fields; however, as one of the key considerations, the mechanical properties of graphene still remain largely unexplored. Herein, by employing focused ion beam irradiation, graphene with various defect levels is obtained and further investigated by using Raman spectroscopy and scanning tunneling microscopy. Specially, our atomic force microscopy based nanomechanical property measurement demonstrates a clear defect density dependent behavior in the elastic modulus of graphene on a substrate as the defect density is higher than a threshold value of 1012 cm−2, where a clear decay is observed in the stiffness of graphene. This defect density dependence is mainly attributed to the appearance of amorphous graphene, which is further confirmed with our molecular dynamics calculations. Therefore, our reported result provides an essential guidance to enable the rational design of graphene materials in nanodevices, especially from the perspective of mechanical properties.

Published
2023
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97. SAT-Based Metabolics Pathways Analysis without Compilation

Author

Peres, Sabine, Morterol, Martin, Simon, Laurent, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Kobsa, Alfred, Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Istrail, Sorin, Series editor, Pevzner, Pavel, Series editor, Waterman, Michael S., Series editor, Mendes, Pedro, editor, Dada, Joseph O., editor, and Smallbone, Kieran, editor

Published
2014
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98. Impact of Community Structure on SAT Solver Performance

Author

Newsham, Zack, Ganesh, Vijay, Fischmeister, Sebastian, Audemard, Gilles, Simon, Laurent, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Kobsa, Alfred, editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Weikum, Gerhard, editor, Sinz, Carsten, editor, and Egly, Uwe, editor

Published
2014
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99. Lazy Clause Exchange Policy for Parallel SAT Solvers

Author

Audemard, Gilles, Simon, Laurent, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Kobsa, Alfred, editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Weikum, Gerhard, editor, Sinz, Carsten, editor, and Egly, Uwe, editor

Published
2014
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