Alimentation et modifications de la composition en acides gras des graisses corporelles des porcs et des volailles.

Conference given outside the academic context (2000)

Combinatorial optimization approaches to the design of load shedding schemes against voltage instability

(2000, October)

This paper proposes a methodology for the design of automatic load shedding against long-term voltage instability. In a first step, a set of training scenarios is set up, corresponding to various ... [more ▼]

This paper proposes a methodology for the design of automatic load shedding against long-term voltage instability. In a first step, a set of training scenarios is set up, corresponding to various operating conditions and disturbances. Each scenario is analyzed to determine the minimal load shedding which stabilizes the system, with due consideration for the shedding location and delay. In a second step, the parameters of a closed-loop undervoltage load shedding scheme are determined so as to: (i) approach as closely as possible the optimal sheddings computed in the first step, over the whole set of scenarios; (ii) stabilize the system in all the unstable scenarios and (iii) shed no load in the stable ones. The corresponding optimization problem is solved using three methods : genetic algorithms, branch and bound approach and the so-called “sequential design”. A detailed example is given on the Hydro-Qu´ebec system in which load shedding is presently planned. [less ▲]

Application of a Mixed Normal Mixture Model for the Estimation of Mastitis-Related Parameters

in Journal of Dairy Science (2000), 83(10), 2341-9

The current methodology for estimating genetic parameters for SCC (SCS) does not account for the difference in SCS between healthy cows and cows with an intramammary infection (IMI). We propose a two ... [more ▼]

The current methodology for estimating genetic parameters for SCC (SCS) does not account for the difference in SCS between healthy cows and cows with an intramammary infection (IMI). We propose a two-component finite mixed normal mixture model to estimate IMI prevalence, separate SCS subpopulation means, individual posterior probabilities of IMI, and SCS variance components. The theory is presented and the expectation-conditional maximization algorithm is utilized to compute maximum likelihood estimates. The methodology is illustrated on two simulated data sets based on the current knowledge of SCS parameters. Maximum likelihood estimates of IMI prevalence and SCS subpopulation means were close to simulated values, except for the estimate of IMI prevalence when both subpopulations were almost confounded. Individual posterior probabilities of IMI were always higher among infected than among healthy cows. Error and additive variance components obtained under the mixture model were closer to simulated values than restricted maximum likelihood estimates obtained assuming a homogeneous SCS distribution, especially when subpopulations were completely separated and when mixing proportion was highest. Convergence was linear and rapid when priors were chosen with caution. The advantages of the methodology are demonstrated, and its feasibility for large data sets is discussed. [less ▲]

Un ordonnanceur assurant des services différenciés relatifs basés sur le délai

in Courtiat, Jean-Pierre; Diaz, Michel; Sénac, Patrick (Eds.) Qualité de Service, multimédia et mobilité (2000, October)

Nous proposons l'ordonnanceur RD-VC garantissant des services différenciés (DiffServ) relativement quantifiés basés sur le délai. Un tel ordonnanceur assure que différentes classes de service obtiennent ... [more ▼]

Nous proposons l'ordonnanceur RD-VC garantissant des services différenciés (DiffServ) relativement quantifiés basés sur le délai. Un tel ordonnanceur assure que différentes classes de service obtiennent des délais inversement proportionnels à des indices de qualité fixés, quelle que soit la charge du réseau, et sans signalisation, ni contrôle d'admission. De plus, bien que cet algorithme ne s'applique qu'aux classes de services, les délais relatifs sont également respectés pour chaque flux composant ces agrégats. Ceci permet d'assurer des qualités de service au niveau des (micro)flux sans que leur grand nombre ne conduise à un effondrement du système. L'algorithme offre de bonnes performances tout en étant très peu coûteux : le traitement par paquet est très léger et il n'est même pas nécessaire de disposer d'une file d'attente par classe de service. [less ▲]

La chirurgie du thymus, normal, involue ou tumoral

in Revue Médicale de Liège (2000), 55(10), 940-4

Thymoma is the most frequently resected mediastinal tumor. Its malignancy is related more to macroscopical findings than to microscopical analysis. All thymomas should be resected, in order to prevent ... [more ▼]

Thymoma is the most frequently resected mediastinal tumor. Its malignancy is related more to macroscopical findings than to microscopical analysis. All thymomas should be resected, in order to prevent malignant degeneration. Furthermore, for the treatment of myasthenia, several centers recommend resection of the thymus, either tumoral (thymoma) or atrophied. Although the role of surgery in this regard is controversial, all authors unanimously stress that complete resection of all thymic remnants is essential to achieve adequate results. [less ▲]

Voyage au pays de Darius et des ayattolahs

Article for general public (2000)

Far ultraviolet imaging of the aurora: new directions

Conference (2000, October)

Cephalees explosives, "en coup de tonnerre": faut-il s'inquieter?

in Revue Médicale de Liège (2000), 55(10), 910914

"Thunderclap" headaches are explosive, extremely intense and sometimes associated with neurological signs or symptoms. As illustrated by the 3 case histories presented here, they are a heterogenous group ... [more ▼]

"Thunderclap" headaches are explosive, extremely intense and sometimes associated with neurological signs or symptoms. As illustrated by the 3 case histories presented here, they are a heterogenous group as far as etiology and prognosis are concerned. They may be symptomatic of an intracranial disorder (subarachnoid hemorrhage, cerebral venous thrombosis, pituitary apoplexia) or idiopathic without any known cause and with a benign, though occasionally recurring, course. They can be spontaneous or triggered by Valsalva maneuvers (cough, exertion, coitus, ...). In certain cases of so-called "idiopathic" thunderclap headache, diffuse, multifocal segmental and reversible vasospasm of cerebral arteries has been found on neuroimaging. As headache characteristics are similar in symptomatic and benign cases, angio-MRI is recommended when CT-scan and CSF examination are normal. [less ▲]

New Functional Aliphatic Polyesters by Chemical Modification of Copolymers of ε-Caprolactone with γ-(2-Bromo-2-methylpropionate)- ε-caprolactone, γ-Bromo- ε-caprolactone, and a Mixture of β-and γ-Ene- ε-caprolactone

in Macromolecules (2000), 33(17), 7751-7760

New functional aliphatic polyesters were prepared by chemical modification of brominated copolyesters. Poly(epsilon-caprolactone)-co-poly(gamma-(2-bromo-2-methylpropionate)-epsilon-caprolactone) copolymer ... [more ▼]

New functional aliphatic polyesters were prepared by chemical modification of brominated copolyesters. Poly(epsilon-caprolactone)-co-poly(gamma-(2-bromo-2-methylpropionate)-epsilon-caprolactone) copolymer was prepared and successfully converted into copolyester bearing methacrylate double bonds by dehydrohalogenation of the pendant tertiary alkyl bromides, thus leading to cross-linkable polyester. The tertiary alkyl bromide groups of the original copolyester were also quaternized by reaction with pyridine, although some side reactions occurred which Limited the reaction yield. Nevertheless, quaternization of the bromide groups of the poly(epsilon-caprolactone)-co-poly(gamma-bromo-epsilon-caprolactone) copolymer proved to be quantitative and to occur without degradation of the polyester chains. This general strategy paves the way to either amphiphilic copolyesters or water-soluble polyesters. The poly(epsilon -caprolactone)-co-poly(gamma -bromo-epsilon-caprolactone) lactone) copolymer was also quantitatively converted into unsaturated copolyester by dehydrohalogenation with formation of double bonds including acrylic-type double bonds. As an alternative, gamma-bromo-epsilon-caprolactone was first dehydrohalogenated, and the unsaturated cyclic monomer was copolymerized with epsilon-caprolactone. Finally, the nonconjugated double bonds of the copolyesters were oxidized into epoxides, except for the acrylic-type unsaturations which remained unchanged. [less ▲]

L’état du logement à Liège

Conference given outside the academic context (2000)