Browsing
     by title


0-9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

or enter first few letters:   
OK
Full Text
Peer Reviewed
See detailAutomatic Scoring of sleep apnea and hypopnea by analysis of mandibular movements
Senny, Frédéric ULg; Destiné, Jacques ULg; Verly, Jacques ULg et al

in M.H.Hamza (Ed.) Proceedings of the 3rd International IASTED International conference on Biomedical Engineering (2005, February)

In this paper, we propose a method for sleep apnea and hypopnea detection by analyzing the mandibular movements recorded during sleep. This signal, highly correlated with the esophageal pressure during ... [more ▼]

In this paper, we propose a method for sleep apnea and hypopnea detection by analyzing the mandibular movements recorded during sleep. This signal, highly correlated with the esophageal pressure during apnea or hypopnea, is a good marker of respiratory efforts. The respiratory efforts and their background activity are used to detect salient mandibular movements related to sleep apnea and hypopnea, to delineate and to recognize episodes of sleep apnea and hypopnea. The method presented may be extended to others breathing disorders such as Respiratory Efforts Related Arousals (RERA). [less ▲]

Detailed reference viewed: 29 (8 ULg)
Full Text
Peer Reviewed
See detailAutomatic shape optimization with GAs and a 2D free surface flow solver
Erpicum, Sébastien ULg; Dewals, Benjamin ULg; Pirotton, Michel ULg

in Proceedings of the 4th International Conference on Advanced Computational Methods in Engineering (2008)

Detailed reference viewed: 25 (4 ULg)
See detailAutomatic stimulus-induced medial premotor cortex activation without perception or action
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

Poster (2010)

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to ... [more ▼]

Evidence from functional imaging studies suggests that well-established stimulus-action associations may induce an automatic activation of the motor preparation system even when there is no intention to make the associated movement (Grezes & Decety, 2002). Here we investigated whether this automatic motor activation can also be elicited by visual stimuli that are not consciously perceived. However, previous subliminal masked experiments used supraliminal response-target in such a way that unconscious mechanisms were inferred from the accumulation of the effect of the subliminal masked stimulus and the motor response. Here, to investigate neural correlates of unconscious process induced by subliminal stimuli, we used event-related BOLD fMRI at 3T to record brain activity in 24 healthy volunteers (mean age: 21 ± 2 years) as they performed a subliminal priming task (see Eimer & Schlaghecken, 1998). In this visuomotor task, participants were asked to make speeded button presses with the left or right hand following double leftward (<< <<) or rightward (>> >>) pointing arrows, which were preceded by a masked subliminal prime of 17 ms (compatible/incompatible arrows or neutral stimulus). Reaction time analysis revealed the classical positive compatibility effect (PCE), mainly shorter reaction times for compatible (mean RT: 369±38 ms) than for incompatible (mean RT: 383± 30 ms) in comparison to neutral trials (mean RT: 375± 38 ms). In a prime identification task, subjects’ performance was at chance level for primes presented for 17 ms, suggesting that the prime was not consciously perceived in the main experiment. Theses behavioral results suggest an automatic and unconscious motor activation induced by the prime. The responded stimuli were randomly intermixed with non-responded stimuli (0 0) with the assumption that the subliminal arrow prime also elicited an automatic motor activation in these passive trials as in responded trials. Imaging analysis of these non-responded trials showed first that activation was mainly restricted to posterior brain areas when using a subliminal stimulus that has not been previously associated with a motor response. Second, when the subliminal stimulus has been strongly associated with a motor response, this activation extended to rostral brain regions classically involved in motor preparation as the SMA, the premotor cortex and the striatum (cluster level p< 0.05 corrected). This finding corroborates the involvement of a fronto-striatal network, especially of the SMA in automatic and unconscious motor activation. [less ▲]

Detailed reference viewed: 24 (3 ULg)
Full Text
Peer Reviewed
See detailAutomatic Stimulus-Induced Medial Premotor Cortex Activation without Perception or Action
D'Ostilio, Kevin ULg; Garraux, Gaëtan ULg

in PLoS ONE (2011), 6(2),

Who has ever been surprised to return to the bowl of salted peanuts without realizing it, even after having eating a moderate number and deciding to stop? Using rapid event-related functional magnetic ... [more ▼]

Who has ever been surprised to return to the bowl of salted peanuts without realizing it, even after having eating a moderate number and deciding to stop? Using rapid event-related functional magnetic resonance imaging (fMRI) in healthy volunteers, we investigated the neural correlates of automatic processes induced by subliminal stimuli. We demonstrated that the automatic activation of motor programs elicited unconsciously in the medial premotor cortex was normally restricted to specific contexts set by the environment, but can occur below the threshold of awareness even when no movement was executed. This novel finding expands our view on brain mechanisms underlying unconscious motor control and provides new evidence that activation of the motor preparation system and consciousness are not obligatory linked. [less ▲]

Detailed reference viewed: 28 (8 ULg)
Full Text
Peer Reviewed
See detailAutomatic Synthesis of [18F]Altanserin, a Radiopharmaceutical for Positron Emission Tomographic Studies of the Serotonergic Type-2 Receptors
Monclus, Michel; Van Naemen, John; Mulleneers, Eric et al

in Clinical Positron Imaging (1998), 1(2), 111-116

[18F]Altanserin is routinely used in several centers to study the serotonergic type-2 receptors (5HT2) with positron emission tomography (PET). An automatic production system allowing the preparation of ... [more ▼]

[18F]Altanserin is routinely used in several centers to study the serotonergic type-2 receptors (5HT2) with positron emission tomography (PET). An automatic production system allowing the preparation of multimillicurie amounts [>1.5 GBq (40 mCi) EOS, mean radiochemical yield 20 ± 6% EOB, specific activity >1 Ci/µmol Image] of this radiopharmaceutical within a synthesis time of 90 minutes (quality controls included) is described in this paper. The apparatus includes the recovery of the activity from the target, the preparation of the dried [18F]KF/kryptofix 2.2.2 complex, the labeling reaction using a microwave cavity, the Sep Pak and HPLC purification. A sterile, pyrogen-free and single use unit was also developed for the formulation of the injectable solution. This last part could be used for the formulation of many other radiopharmaceuticals. [less ▲]

Detailed reference viewed: 18 (1 ULg)
Full Text
Peer Reviewed
See detailAutomatic Synthesis of Specifications from the Dynamic Observation of Reactive Programs
Boigelot, Bernard ULg; Godefroid, Patrice

in Lecture Notes in Computer Science (1997), 1217

VeriSoft is a tool for systematically exploring the state spaces of systems composed of several concurrent processes executing arbitrary C (or C++) code. VeriSoft can automatically detect coordination ... [more ▼]

VeriSoft is a tool for systematically exploring the state spaces of systems composed of several concurrent processes executing arbitrary C (or C++) code. VeriSoft can automatically detect coordination problems between the concurrent processes of a system. In this paper, we present a method to synthesize a finite-state machine that simulates all the sequences of visible operations of a given process that were observed during a state-space exploration performed by VeriSoft. The examination of this machine makes it possible to discover the dynamic behavior of the process in its environment and to understand how it contributes to the global behavior of the system. [less ▲]

Detailed reference viewed: 1 (1 ULg)
See detailAutomatic Target Recognition for LADAR Imagery Using Functional Templates Derived From 3-D CAD Models
Verly, Jacques ULg; Lacoss, Richard T.

in Firschein, O.; Strat, T. (Eds.) Reconnaissance, Surveillance, and Target Acquisition for the Unmanned Ground Vehicle: Providing Surveillance ’Eyes’ for an Autonomous Vehicle (1997)

Detailed reference viewed: 6 (1 ULg)
Full Text
See detailAutomatic target recognition using passive bistatic radar signals
Pisane, Jonathan ULg

Doctoral thesis (2013)

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e ... [more ▼]

We present the design, development, and test of three novel, distinct automatic target recognition (ATR) systems for the recognition of airplanes and, more specifically, non- cooperative airplanes, i.e. airplanes that do not provide information when interrogated, in the framework of passive bistatic radar systems. Passive bistatic radar systems use one or more illuminators of opportunity (already present in the field), with frequencies up to 1 GHz for the transmitter part of the systems considered here, and one or more receivers, deployed by the persons managing the system, and not co-located with the transmitters. The sole source of information are the signal scattered on the airplane and the direct-path signal that are collected by the receiver, some basic knowledge about the transmitter, and the geometrical bistatic radar configuration. The three distinct ATR systems that we built respectively use the radar images, the bistatic complex radar cross-section (BS-RCS), and the bistatic radar cross-section (BS- RCS) of the targets. We use data acquired either on scale models of airplanes placed in an anechoic, electromagnetic chamber or on real-size airplanes using a bistatic testbed consisting of a VOR transmitter and a software-defined radio (SDR) receiver, located near Orly airport, France. We describe the radar phenomenology pertinent for the problem at hand, as well as the mathematical underpinnings of the derivation of the bistatic RCS values and of the construction of the radar images. For the classification of the observed targets into pre-defined classes, we use either extremely randomized trees or subspace methods. A key feature of our approach is that we break the recognition problem into a set of sub-problems by decomposing the parameter space, which consists of the frequency, the polarization, the aspect angle, and the bistatic angle, into regions. We build one recognizer for each region. We first validate the extra-trees method on the radar images of the MSTAR dataset, featuring ground vehicles. We then test the method on the images of the airplanes constructed from data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.99. We test the subspace methods on the BS-CRCS and on the BS-RCS of the airplanes extracted from the data acquired in the anechoic chamber, achieving a probability of correct recognition up to 0.98, with variations according to the frequency band, the polarization, the sector of aspect angle, the sector of bistatic angle, and the number of (Tx,Rx) pairs used. The ATR system deployed in the field gives a probability of correct recognition of 0.82, with variations according to the sector of aspect angle and the sector of bistatic angle. [less ▲]

Detailed reference viewed: 126 (12 ULg)
Full Text
Peer Reviewed
See detailAutomatic target recognition with passive bistatic radars, with applications to the detection of anomalies in the civilian air traffic
Pisane, Jonathan ULg; Azarian, Sylvain; Lesturgie, Marc et al

Conference (2013, April 19)

Detailed reference viewed: 36 (1 ULg)
Full Text
See detailAutomatic time step size determination and automatic Hessian matrix actualisation selection for non-linear dynamic problems solved by implicit schemes
Noels, Ludovic ULg; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg

(2000)

An automatic time step size determination for non-linear problems, solved by implicit schemes, is presented. The time step calculation is based on the estimation of the integration error. This estimation ... [more ▼]

An automatic time step size determination for non-linear problems, solved by implicit schemes, is presented. The time step calculation is based on the estimation of the integration error. This estimation is calculated from the acceleration difference. It is normalised according to the size of the problem and the integration parameters. This time step control algorithm modifies the time step size only if the problem has a long time physical change. On the other hand, Hessian matrix can be kept constant for several iterations however the problem is non-linear. According to the fact that the time step size is constant for some time step, the Hessian matrix shouldn’t be recalculated for each time step. A criterion selecting if Hessian matrix must be calculated or not is developed. Finally, a criterion of iterations divergence is also proposed. It avoids the determination, by the user, of a maximal iterations number. The iterations number is the smaller. Industrial numerical examples are presented that demonstrated the performances (precision and computational cost) of the algorithms. [less ▲]

Detailed reference viewed: 74 (7 ULg)
Full Text
Peer Reviewed
See detailAutomatic time stepping algorithms for implicit numerical simulations of blade/casing interactions
Noels, Ludovic ULg; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg et al

in International Journal of Crashworthiness (2001), 6(3), 351-362

An automatic time stepping algorithm for non-linear problems, solved by implicit schemes, is presented. The time step computation is based on the estimation of an integration error calculated from the ... [more ▼]

An automatic time stepping algorithm for non-linear problems, solved by implicit schemes, is presented. The time step computation is based on the estimation of an integration error calculated from the acceleration difference. It is normalised according to the size of the problem and the integration parameters. This time step control algorithm modifies the time step size only if the problem has a long time physical change. Additionally, the Hessian matrix can be kept constant for several iterations, even though the problem is non-linear. A criterion selecting if the Hessian matrix must be calculated or not is developed. Finally, a criterion of iterations divergence is also proposed. It avoids the determination, by the user, of a maximal iteration number. This minimises the total number of iterations, and thus the computation cost. Industrial numerical examples are presented that demonstrate the performances (precision and computational cost) of the algorithms. [less ▲]

Detailed reference viewed: 48 (4 ULg)
Full Text
Peer Reviewed
See detailAutomatic time stepping algorithms for implicit numerical simulations of non-linear dynamics
Noels, Ludovic ULg; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg et al

in Advances in Engineering Software (2002), 33(7-10, JUL-OCT), 589-603

When an implicit integration scheme is used, variable step strategies are especially well suited to deal with problems characterized by high non-linearities. Constant step size strategies generally lead ... [more ▼]

When an implicit integration scheme is used, variable step strategies are especially well suited to deal with problems characterized by high non-linearities. Constant step size strategies generally lead to divergence or extremely costly computations. An automatic time stepping algorithm is proposed that is based on estimators of the integration error of the differential dynamic balance equations. Additionally, the proposed algorithm automatically takes decisions regarding the necessity of updating the tangent matrix or stopping the iterations, further reducing the computational cost. As an illustration of the capabilities of this algorithm, several numerical simulations of both academic and industrial problems are presented. (C) 2002 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved. [less ▲]

Detailed reference viewed: 37 (7 ULg)
Full Text
See detailAutomatic time stepping algorithms for implicit numerical simulations of non-linear dynamics
Noels, Ludovic ULg; Stainier, Laurent ULg; Ponthot, Jean-Philippe ULg et al

in Topping, B. H. V.; Motas Soares, C. A. (Eds.) FINITE ELEMENTS: TECHNIQUES AND DEVELOPMENTS (2000)

Variable step strategies are specially well suited to deal with problems characterized by high non-linearity and contact/impact. Both phenomena are typical of dynamic simulations of the interactions ... [more ▼]

Variable step strategies are specially well suited to deal with problems characterized by high non-linearity and contact/impact. Both phenomena are typical of dynamic simulations of the interactions between a turbine blade and its casing, the most dramatic example being blade loss. Constant step size strategies do not give satisfactory answer for this kind of problems, since it is very difficult, if not impossible, for the user to find an appropriate time step that does not lead to divergence nor generate extremely costly computations. An automatic time stepping algorithm is proposed, which takes into account the recent history of accelerations in the bodies under consideration. More precisely, the adaptation algorithm is based on estimators of the integration error of the differential dynamic balance equations. This allows for adaptation of the time step to capture correctly the transient phenomena, with characteristic times which can range from relatively long (in regime) to very short (blade loss), thus ensuring precision while keeping the computation cost to a minimum. Additionally, the proposed algorithm automatically takes decisions regarding the necessity of updating the tangent matrix or stopping the iterations, further reducing the computational cost. As an illustration of the capabilities of this algorithm, several numerical simulations of both academic and industrial (the contact/impact between a turbine blade and the casing) problems will be presented. [less ▲]

Detailed reference viewed: 43 (5 ULg)
Peer Reviewed
See detailAutomatic X-ray fluorescence scanning mobile system for 2D chemical analysis
Strivay, David ULg; Hocquet, François-Philippe; Dister, Hervé et al

Conference (2012, December)

Detailed reference viewed: 32 (3 ULg)
See detailAutomatiisation: actualité et perspectives
MELIN, Pierrette ULg

Scientific conference (1996, March)

Detailed reference viewed: 3 (0 ULg)
See detailAutomation en microbiologie: Actualité et perspectives
MELIN, Pierrette ULg

Conference (1996, June 05)

Detailed reference viewed: 12 (1 ULg)
See detailAutomation for the Measurement of Selected PBDEs in Human Serum
Focant, Jean-François ULg

Scientific conference (2011, August)

Detailed reference viewed: 5 (2 ULg)
See detailAutomation in Identification and Susceptibility Testing
Melin, Pierrette ULg; De Mol, Patrick ULg

Conference (2001, June 14)

Detailed reference viewed: 10 (1 ULg)
Full Text
Peer Reviewed
See detailAutomatisation d'un banc de répartition pour buses de pulvérisation
Lebeau, Frédéric ULg; Hamza, Elies; Destain, Marie-France ULg

in Cahiers Agricultures (2000)

Les bancs de répartition constituent l'élement de base permettant de tester la sensibilité de la distribution transversale des buses de pulvérisation aux différents paramètres de fonctionnement. L'article ... [more ▼]

Les bancs de répartition constituent l'élement de base permettant de tester la sensibilité de la distribution transversale des buses de pulvérisation aux différents paramètres de fonctionnement. L'article présente un banc d'essai conforme à la norme ISO 5682/1 qui permet une lecture automatisée des différentes grandeurs (pression, débit, volume recueilli). [less ▲]

Detailed reference viewed: 101 (25 ULg)
Full Text
See detailL'automatisation dans l'agriculture et dans l'industrie agro-alimentaire. Un exemple : le tri des fruits en fonction de leurs caractéristiques externes
Leemans, Vincent ULg; Destain, Marie-France ULg

Scientific conference (1997, May 15)

Séminaire de vulgarisation sur l'utilisation des techniques d'analyse d'image pour l'évaluation de la forme de fruit et pour la recherche de défauts.

Detailed reference viewed: 89 (6 ULg)