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Peer Reviewed
See detailContexual sensitization to the behavioral effects of cocaine in neonatal rats
Tirelli, Ezio ULg

in Developmental Psychobiology (1999), 25

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See detailContinental-scale variability in browser diversity is a major driver of diversity patterns in acacias across Africa
Greve, M; Lykke, A M; Fagg, C W et al

in Journal of Ecology (2012), 100

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See detailContingency filtering techniques for preventive security-constrained optimal power flow
Capitanescu, Florin ULg; Glavic, M.; Ernst, Damien ULg et al

in IEEE Transactions on Power Systems (2007), 22(4), 1690-1697

This paper focuses on contingency filtering to accelerate the iterative solution of preventive security-constrained optimal power flow (PSCOPF) problems. To this end, we propose two novel filtering ... [more ▼]

This paper focuses on contingency filtering to accelerate the iterative solution of preventive security-constrained optimal power flow (PSCOPF) problems. To this end, we propose two novel filtering techniques relying on the comparison at an intermediate PSCOPF solution of post-contingency constraint violations among postulated contingencies. We assess these techniques by comparing them with severity index-based filtering schemes, on a 60- and a 118-bus system. Our results show that the proposed contingency filtering techniques lead to faster solution of the PSCOPF, while being more robust and meaningful, than severity-index based ones. [less ▲]

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See detailA contingency filtering, ranking and assessment technique for on-line transient stability studies
Ruiz-Vega, Daniel; Ernst, Damien ULg; Machado Ferreira, C. et al

in Proceedings of International Conference on Electric Utility Deregulation and Restructing and Power Technologies 2000 (2000)

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See detailContingency ranking with respect to overloads in very large power systems taking into account uncertainty, preventive, and corrective actions
Fliscounakis, Stéphane; Panciatici, Patrick; Capitanescu, Florin et al

in IEEE Transactions on Power Systems (2013)

This paper deals with day-ahead security management with respect to a postulated set of contingencies, while taking into account uncertainties about the next day generation/load scenario. In order to help ... [more ▼]

This paper deals with day-ahead security management with respect to a postulated set of contingencies, while taking into account uncertainties about the next day generation/load scenario. In order to help the system operator in decision making under uncertainty, we aim at ranking these contingencies into four clusters according to the type of control actions needed to cover the worst uncertainty pattern of each contingency with respect to branch overload. To this end we use a fixed point algorithm that loops over two main modules: a discrete bi-level program (BLV) that computes the worst-case scenario, and a special kind of security constrained optimal power flow (SCOPF) which computes optimal preventive/corrective actions to cover the worst-case. We rely on a DC grid model, as the large number of binary variables, the large size of the problem, and the stringent computational requirements preclude the use of existing mixed integer nonlinear programming (MINLP) solvers. Consequently we solve the SCOPF using a mixed integer linear programming (MILP) solver while the BLV is decomposed into a series of MILPs. We provide numerical results with our approach on a very large European system model with 9241 buses and 5126 contingencies. [less ▲]

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See detailContingency severity assessment for voltage security using non-parametric regression techniques
Wehenkel, Louis ULg

in IEEE Transactions on Power Systems (1996), 11(1), 101-111

This paper proposes a novel approach to power system voltage security assessment exploiting nonparametric regression techniques to extract simple, and at the same time reliable, models of the severity of ... [more ▼]

This paper proposes a novel approach to power system voltage security assessment exploiting nonparametric regression techniques to extract simple, and at the same time reliable, models of the severity of a contingency, defined as the difference between pre- and post-contingency load power margins. The regression techniques extract information from large sets of possible operating conditions of a power system screened offline via massive random sampling, whose voltage security with respect to contingencies is pre-analyzed using an efficient voltage stability simulation. In particular, regression trees are used to identify the most salient parameters of the pre-contingency topology and electrical state which influence the severity of a given contingency, and to provide a first guess transparent approximation of the contingency severity in terms of these latter parameters. Multilayer perceptrons are exploited to further refine this information. The approach is demonstrated on a realistic model of a large scale voltage stability limited power system, where it shows to provide valuable physical insight and reliable contingency evaluation. Various potential uses in power system planning and operation are discussed [less ▲]

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See detailContingent negative variation (CNV) as a diagnostic and physiopathologic tool in headache patients
SCHOENEN, Jean ULg; Maertens De Noordhout, Alain ULg; Timsit-Berthier, M. et al

in Clifford Rose, F. (Ed.) Migraine Proc. (1985)

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See detailContingent negative variation abnormalities in posttraumatic stress disorder
Papart, Patrick ULg; Ansseau, Marc ULg; Bartholomé, F.

in European Neuropsychopharmacology (2008), 18(Suppl 4), 481-482

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See detailContingent negative variation and efficacy of beta-blocking agents in migraine
Schoenen, Jean ULg; MAERTENS DE NOORDHOUT, Alain ULg; Timsit-Berthier, Martine et al

in Cephalalgia : An International Journal of Headache (1986), 6(4), 229-33

Thirty-three patients with common migraine underwent contingent negative variation (CNV) recordings before receiving prophylactic beta-blocker treatment with either metoprolol (27 patients) or propranolol ... [more ▼]

Thirty-three patients with common migraine underwent contingent negative variation (CNV) recordings before receiving prophylactic beta-blocker treatment with either metoprolol (27 patients) or propranolol (6 patients) at mean daily dosages of 110 mg and 122 mg, respectively. After 3 months the therapeutic efficacy of the beta-blocker was assessed in each patient by means of a global severity score and compared with the initial CNV recordings. The mean clinical improvement was 62%. A significant positive correlation was found between CNV amplitude before prophylaxis and the clinical response to beta-blockers: patients with higher CNV tended to respond better to therapy. Eight of 10 patients with a CNV amplitude higher than -25 microV had a more than 50% reduction of the severity score--that is, a good or excellent response to the beta-blocking agent--whereas only 2 of 9 patients with an amplitude lower than -20 microV had a good response. [less ▲]

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See detailContingent negative variation and severity of depression
Papart, Patrick ULg; Ansseau, Marc ULg; Devoitille, J.M. et al

in Psychiatry: A world perspective - Volume 2 (1990)

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See detailThe contingent negative variation CNV during a three second foreperiod in migraine patients
Böcker, K. B. E.; Timsit-Berthier, M.; Schoenen, Jean ULg et al

in Brunia, C. H. M.; Gaillard, A. W. K.; Kok, A. (Eds.) Psychophysiological Brain Research (1990)

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See detailContingent Negative Variation in Headache
MAERTENS DE NOORDHOUT, Alain ULg; Timsit-Berthier, Martine; Timsit, M. et al

in Annals of Neurology (1986), 19(1), 78-80

Contingent negative variation (CNV), an event-related slow cerebral potential, was analyzed in 79 consecutive headache patients. Compared to normal controls (n = 33), CNV did not differ in tension ... [more ▼]

Contingent negative variation (CNV), an event-related slow cerebral potential, was analyzed in 79 consecutive headache patients. Compared to normal controls (n = 33), CNV did not differ in tension headache (n = 21) or in combined headaches with a predominant tension component (n = 13). The mean amplitude of CNV was significantly (p less than 0.001) increased in migraine (n = 29) as well as in combined headache with predominant migraine (n = 16). All migraineurs were studied between attacks and without prophylactic treatment. CNV may be a useful diagnostic test in headache. Its increased amplitude in migraine might reflect central catecholaminergic hyperactivity. [less ▲]

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See detailContingent Negative Variation in Migraine
Bocker, K. B.; Timsit-Berthier, M.; Schoenen, Jean ULg et al

in Headache (1990), 30(9), 604-9

The Contingent Negative Variation (CNV) is an event-related slow potential. It was recorded in healthy volunteers (n = 8) and in patients suffering from migraine without (n = 12) or with (n = 5) aura ... [more ▼]

The Contingent Negative Variation (CNV) is an event-related slow potential. It was recorded in healthy volunteers (n = 8) and in patients suffering from migraine without (n = 12) or with (n = 5) aura, during one (CNV1) and three second (CNV3) foreperiods in a forewarned reaction time task. CNV1 was recorded at the vertex while CNV3 was recorded at multiple electrode sites to assess topographical differences. Seven out of twelve migraine patients without aura had increased CNV1 amplitudes. CNV3 amplitudes were increased as well, but only at electrode positions C3 and C4 and not at Fz. CNV3, which allows for analysis of both an early and a late CNV component, could improve the discrimination of migraine without aura beyond that of CNV1. In migraine with aura all CNV parameters were at control levels, confirming previous results. The data obtained are discussed in terms of arousal, activation and stress and the "biobehavioral model of migraine" (Welch, 1986). [less ▲]

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See detailContingent negative variation in psychopharmacology
Timsit-Berthier, M.; Ansseau, Marc ULg; Mantanus, H. et al

in Brunia, C. H. M.; Mulder, G.; Verbater, M. N. (Eds.) Event related potentials in brain research (1990)

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See detailContingent negative variation: methods and potential interest in headache.
Schoenen, Jean ULg; Timsit-Berthier, M.

in Cephalalgia : An International Journal of Headache (1993), 13(1), 28-32

Contingent negative variation (CNV) is an event-related slow cerebral potential which has been found abnormal in migraine. Its methodology is described. Contrary to other neurophysiological techniques ... [more ▼]

Contingent negative variation (CNV) is an event-related slow cerebral potential which has been found abnormal in migraine. Its methodology is described. Contrary to other neurophysiological techniques, CNV needs special equipment and expertise. On average, CNV amplitude is increased and its habituation is lacking in migraine without aura between attacks, but not in migraine with aura. The sensitivity of CNV as a diagnostic tool is low, but its specificity is high. CNV amplitude normalizes after treatment with beta-blockers. The CNV abnormalities in migraine might be due to hyperreactivity of central catecholaminergic pathways. [less ▲]

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See detailContingentement de quelques productions agricoles dans la CEE
Bergans, J.; Burny, Philippe ULg; Detraux, M. et al

in Journal des Ingénieurs (Le) (1987), 16(1), 5-9

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See detailContinuation and bifurcation analysis of a periodically forced excitable system
Croisier, Huguette; Dauby, Pierre ULg

in Journal of Theoretical Biology (2007), 246(3), 430-448

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See detailContinuation of Higher Order Harmonic Balance Solutions for Nonlinear Aeroelastic Systems
Dimitriadis, Grigorios ULg

in Journal of Aircraft (2008), 45(2), 523-537

The Harmonic Balance method is a very useful tool for characterizing and predicting the response of nonlinear dynamic systems undergoing periodic oscillations, either self-excited or due to harmonic ... [more ▼]

The Harmonic Balance method is a very useful tool for characterizing and predicting the response of nonlinear dynamic systems undergoing periodic oscillations, either self-excited or due to harmonic excitation. The method and several of its variants have been applied to nonlinear aeroelastic systems over the last two decades. This paper presents a detailed description of several Harmonic Balance methods and a continuation framework allowing the methods to follow the response of dynamic systems from the bifurcation point to any desired parameter value, while successfully negotiating further fold bifurcations. The continuation framework is described for systems undergoing sub-critical and super-critical Hopf bifurcations as well as a particular type of explosive bifurcation. The methods investigated in this work are applied to a nonlinear aeroelastic model of a Generic Transport Aircraft featuring polynomial or freeplay stiffness nonlinearity in the control surface. It is shown that high order Harmonic Balance solutions will capture accurately the complete bifurcation behavior of this system for both types of nonlinearity. Low order solutions can become inaccurate in the presence of numerous folds in the Limit Cycle Oscillation branch but can still yield practical engineering information at a fraction of the cost of higher order solutions. Time domain Harmonic Balance schemes are shown to be more computationally expensive than the standard Harmonic Balance approach. [less ▲]

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