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
See detailLes quasars.
Henry, A.; Swings, Jean-Pierre ULg; Gosset, Eric ULg

in Ciel (Le) (1984), 46

Not Available

Detailed reference viewed: 6 (2 ULg)
Peer Reviewed
See detailQuasi 2D-numerical model of aerated flow over stepped chutes
Dewals, Benjamin ULg; André, Stéphanie

Conference (2003, August 29)

Detailed reference viewed: 3 (1 ULg)
Full Text
Peer Reviewed
See detailQuasi 2D-numerical model of aerated flow over stepped chutes
André, Stéphanie; Dewals, Benjamin ULg; Pirotton, Michel ULg et al

in Proc. 30th IAHR Congress (2003)

Aerated flow over stepped chutes is principally studied on laboratory models. Consequently, the obtained design relations have a limited field of application. In order to propose a more general ... [more ▼]

Aerated flow over stepped chutes is principally studied on laboratory models. Consequently, the obtained design relations have a limited field of application. In order to propose a more general description of the flow, a quasi-2D numerical model is developed. The fluid is considered as an air-water mixture governed by the shallow-water equations. Moreover, a transport equation for air concentration represents the self-aeration of the flow and a coefficient of uneven vertical velocity distribution integrates indirectly the turbulent structures. The paper includes a brief description of the flow behaviour, the quasi-2D model equations, and a comparison of the numerical results with the measured flow characteristics in a 30° stepped flume. [less ▲]

Detailed reference viewed: 66 (5 ULg)
Full Text
See detailQuasi steady-state models for long-term voltage and frequency dynamics simulation
Grenier, Marie-Eve; Lefebvre, Daniel; Van Cutsem, Thierry ULg

(2005, June)

The Quasi Steady-State (QSS) approximation of long-term dynamics relies on time-scale decomposition and consists of replacing faster phenomena by their equilibrium conditions, in order to reduce the ... [more ▼]

The Quasi Steady-State (QSS) approximation of long-term dynamics relies on time-scale decomposition and consists of replacing faster phenomena by their equilibrium conditions, in order to reduce the complexity of the whole model and increase the computation efficiency of time simulations. This paper describes the extension of a QSS model extensively used in long-term voltage stability studies, to readily incorporate the frequency dynamics that takes place over the same time scale. This extended QSS model relies on a common-frequency assumption. Its advantages, limitations and possible improvements are discussed through simulation results on the Hydro-Québec system, where it has been compared to full time scale simulations. Disturbances with an impact on either frequency or voltages are considered and the coupling between these two aspects of long-term dynamics is briefly discussed. [less ▲]

Detailed reference viewed: 81 (4 ULg)
Full Text
Peer Reviewed
See detailQuasi steady-state simulation diagnosis using Newton method with optimal multiplier
Rousseaux, Patricia ULg; Van Cutsem, Thierry ULg

in IEEE PES General Meeting (Montreal) (2006)

This paper deals with the quasi steady-state approximation of the long-term dynamics. This fast time simulation method assumes that the short-term dynamics are stable and can be replaced by their ... [more ▼]

This paper deals with the quasi steady-state approximation of the long-term dynamics. This fast time simulation method assumes that the short-term dynamics are stable and can be replaced by their equilibrium equations. When the latter stop having a solution, the simulation undergoes a singularity. This paper proposes a method to identify which component(s) are responsible for the loss of equilibrium. The corresponding equations are identified using the Newton method with optimal multiplier. The method has been validated with respect to full time simulation. Very good results are shown on the Nordic-32 system, in cases where long-term voltage instability triggers loss of synchronism. The proposed method enhances time simulation at very low computational cost and can also help correcting model and/or operating point errors. [less ▲]

Detailed reference viewed: 78 (10 ULg)
Full Text
See detailQuasi umbræ entium. Suárez e Brentano sull’ens rationis
Boccaccini, Federico ULg

in Sgarbi, Marco (Ed.) Francisco Suárez and His Legacy. The Impact of Suarezian Metaphysics and Epistemology on Modern Philosophy (2010)

Detailed reference viewed: 12 (0 ULg)
Full Text
Peer Reviewed
See detailQuasi-asymptotic development of conditioned hyperactivity induced by intermittent injections of cocaine in C57BL/6J mice
Brabant, Christian ULg; Tambour, Sophie ULg; Tirelli, Ezio ULg

in Pharmacology, Biochemistry & Behavior (2003), 75(2), 273-280

The emergence of a conditioned cocaine-induced hyperlocomotion was examined in C57BL/6J mice using a procedure that has not been used previously. Two days after a session of preexposure to the test ... [more ▼]

The emergence of a conditioned cocaine-induced hyperlocomotion was examined in C57BL/6J mice using a procedure that has not been used previously. Two days after a session of preexposure to the test chambers under saline, a first group of mice (cocaine-cued) received five once-daily injections of 10-mg/kg sc cocaine every other day (on the odd days of the chronic treatment period) and a saline injection on the 5 days following each cocaine injection day (on the even days of the treatment period), in all cases before being placed in the test chamber. Another group of mice (saline-cued) received 10 injections of saline on both the even and the odd days in the same context, and a third group of mice (cocaine-uncued) received five injections of saline on the even days in the test context and five injections of cocaine on the odd days in an alternative context. On the odd days sessions, the cocaine-cued group showed significant repeated increases in locomotion without behavioural sensitisation being induced, whereas the saline-cued levels of locomotion remained on baseline levels. On the first even session, the three groups did not differ from each other and showed lower levels of locomotion than on the preexposure session. During the two following even sessions, the cocaine-cued group showed an increase in locomotion that levelled off on the two remaining sessions, whereas the saline-cued and the cocame-uncued groups (which presented comparable values) exhibited significantly lower levels of locomotion. That pattern of successive placebo responses resembles the typical S-shaped development of a Pavlovian conditioned response, albeit the increase described here was quite rapid. The protocol used here may provide an additional method for the experimental analysis of stimulant-induced conditioned placebo activity. (C) 2003 Elsevier Science Inc. All rights reserved. [less ▲]

Detailed reference viewed: 9 (1 ULg)
Full Text
See detailQuasi-consistent filter passbands and the homogeneity of photometric indices
Sterken, Christiaan; Manfroid, Jean ULg

in Liege International Astrophysical Colloquia (1987)

The authors present observational data which clearly illustrate that slight differences in filter passbands cause large systematic effects in the transformation of some photometric indices. The effect is ... [more ▼]

The authors present observational data which clearly illustrate that slight differences in filter passbands cause large systematic effects in the transformation of some photometric indices. The effect is surprisingly large in the case of early B stars where in particular the Strömgren m[SUB]1[/SUB] and c[SUB]1[/SUB] indices are affected. The possible consequences for the position of the β Cephei instability strip in the observational H-R diagram of the young reddened cluster NGC 3293 are discussed. [less ▲]

Detailed reference viewed: 16 (1 ULg)
Full Text
Peer Reviewed
See detailA Quasi-Coulomb Model for Frictional Contact Interfaces
Garcìa Garino, C.; Ponthot, Jean-Philippe ULg; Boman, Romain ULg et al

in MECOM'99 - Proceedings of the 6th Argentine Congress on Computational Mechanics (1999, September)

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in ... [more ▼]

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in order to describe the constitutive law for the frictional case. Following a standard plasticity approach to Coulomb law a non-symmetric tangent operator is found, and so a non-symmetric solver has to be used in order to take full advantage of consistent operators. With respect to symmetric ones, these non-symmetric operators lead to prohibitive computational times. However, in practice different schemes have been proposed in order to recover the symmetric operator, and consequently, use a symmetric solver. In this work an alternative approach based on an idea due to Garcia Garino and Oliver [33] is defined in order to avoid to deal with non-symmetric solvers and thus save a large amount of computational time, which renders the computational simulation more attractive to industry. Applications to metal forming simulations and crashworthiness analysis are envisaged. [less ▲]

Detailed reference viewed: 30 (10 ULg)
Peer Reviewed
See detailA Quasi-Coulomb Model for Frictional Contact Interfaces
GARCIA-GARINO, C.; Ponthot, Jean-Philippe ULg; OLIVER, J.

in Idelsohn, S.; Onate; Dvorkin (Eds.) Proceedings of "World Congress on Computational Mechanics IV (1998)

Detailed reference viewed: 9 (1 ULg)
Full Text
Peer Reviewed
See detailA quasi-coulomb model for frictional contact interfaces. Application to metal forming simulations
Garcia-Garino, Carlos; Ponthot, Jean-Philippe ULg

in Latin American Applied Research (2008), 38(2), 95-104

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in ... [more ▼]

Frictional contact interfaces have to be modeled in practice when industrial problems such as metal forming operations, crashworthiness, and so on, have to be simulated. Usually a Coulomb model is used in order to describe the constitutive law for the frictional case. Following a standard non associated plasticity approach to Coulomb law a non-symmetric tangent operator results, and so a non-symmetric solver has to be used in order to take full advantage of consistent operators. With respect to symmetric ones, these non-symmetric operators lead to prohibitive computational times. However, in practice different schemes have been proposed in order to recover the symmetric operator, and consequently, use a symmetric solver. In this work an alternative approach based on an idea due to Garcia Garino and Oliver (1992) is defined in order to avoid to deal with non-symmetric solvers and thus save a large amount of computational time, which renders the computational simulation more attractive to industry. Applications to metal forming simulations and crashworthiness analysis are considered. [less ▲]

Detailed reference viewed: 37 (0 ULg)
Full Text
See detailQuasi-Elastic Production at Hadronic Colliders
Dechambre, Alice ULg

Book published by Les Editions de l'Université de Liège (2010)

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of ... [more ▼]

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of hadronic remnants after the interaction. In view of the recent data from CDF Run II, we critically re-evaluated the standard approach to the calculation of quasi-elastic cross sections in the high-energy limit and evaluated the uncertainties that affect this kind of process. The main idea of this work was to understand the various ingredients that enter the calculation and the uncertainties coming from each of them. We studied and narrowed down these uncertainties using available data on dijets quasi-elastic event at the TeVatron. All the arguments developed apply to high-mass central systems and lead to a prediction of the Higgs quasi-elastic cross section at the LHC energies. [less ▲]

Detailed reference viewed: 57 (18 ULg)
Full Text
See detailQuasi-Elastic Production at Hadronic Colliders
Dechambre, Alice ULg

Doctoral thesis (2010)

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of ... [more ▼]

Quasi-elastic production is usually viewed as a golden signal for the detection of objects such as the Higgs boson(s) or exotic particles and this is due to the very clean final state and the lack of hadronic remnants after the interaction. In view of the recent data from CDF Run II, we critically re-evaluated the standard approach to the calculation of quasi-elastic cross sections in the high-energy limit and evaluated the uncertainties that affect this kind of process. The main idea of this work was to understand the various ingredients that enter the calculation and the uncertainties coming from each of them. We studied and narrowed down these uncertainties using available data on dijets quasi-elastic event at the TeVatron. All the arguments developed apply to high-mass central systems and lead to a prediction of the Higgs quasi-elastic cross section at the LHC energies. [less ▲]

Detailed reference viewed: 10 (1 ULg)
Full Text
See detailQuasi-loss of nationality - a new concept or a non-issue?
Wautelet, Patrick ULg; de Groot, Gerard-René

Conference (2014, April)

Quasi-loss of nationality : “is this a loss I see before me?” Prof. Gerard-René de Groot (University Maastricht, Aruba and Hasselt) Prof. Patrick Wautelet (University Liège) This paper focuses on ... [more ▼]

Quasi-loss of nationality : “is this a loss I see before me?” Prof. Gerard-René de Groot (University Maastricht, Aruba and Hasselt) Prof. Patrick Wautelet (University Liège) This paper focuses on situations in which a person is said never to have had the nationality of a country, even though (s)he assumed (and in many cases the authorities of the country concerned shared that assumption) that (s)he possessed that nationality. Contrary to situations of loss of nationality, where something is taken away which existed, those situations involve a decision that a nationality was never acquired. This subtle distinction between loss and non-acquisition will in most cases be lost on the persons concerned who will experience the decision as a loss of nationality. The central question of this paper is, whether these situations of quasi-loss differ so much from loss cases, that they have to be treated differently. If and insofar as this would be the case, a next question is, whether a person should under certain circumstances be protected against quasi-loss of her or his nationality. In order to answer these questions, the paper will first attempt to map out situations of quasi-loss in EU member states. Typical cases will be described in which a person did never acquire the nationality of the country, although (s)he was considered as a national before certain facts happened. Drawing on this taxonomy, the paper will offer a first attempt at uncovering whether national, European and international law offer some protection, and if yes, to which extent, for situations of quasi-loss. This paper will conclude with outlining best practices which Member States should comply with in handling quasi-loss situations. [less ▲]

Detailed reference viewed: 14 (0 ULg)
See detailLe "quasi-marché" de l'accompagnement des demandeurs d'emploi
Remy, Céline ULg

Conference given outside the academic context (2013)

Detailed reference viewed: 6 (0 ULg)
Full Text
See detailA quasi-Newton algorithm for first-odrer saddle-point location
Culot, Patrick; Dive, Georges ULg; Nguyen, Van Hen et al

in Theoretica Chimica Acta (1992), 82

A new algorithm for the location of a transition-state structure on an energy hypersurface is proposed. The method is compared to three other quasi-Newton step calculations available in literature ... [more ▼]

A new algorithm for the location of a transition-state structure on an energy hypersurface is proposed. The method is compared to three other quasi-Newton step calculations available in literature. Numerical results derived from several examples are compared to those obtained by the two algorithms implemented in the Gaussian package. [less ▲]

Detailed reference viewed: 26 (6 ULg)
Full Text
See detailA Quasi-One Dimensiona Model for Axial Turbines
Adam, Olivier; Léonard, Olivier ULg

in Proceedings of the 18th ISABE Conference (2007, September)

An axial turbine model is presented that is intended to predict its aerodynamic performance based only on the turbine geometry and thermodynamic environment. The model is an extension of an existing quasi ... [more ▼]

An axial turbine model is presented that is intended to predict its aerodynamic performance based only on the turbine geometry and thermodynamic environment. The model is an extension of an existing quasi-1D compressor representation. The simulation tool is able to compute the flow through a whole multistage turbine, with detail at the blade row level. It relies upon a quasi-one dimensional Euler system of equations, expressed here in curvilinear coordinates, and resulting from the application of mass, momentum and energy conservation principles in finite-volume formalism. The source terms expressing the interactions between the flow, the blades and the flowpath are determined using the velocity triangles for each blade row, at mid-span. The solver performs an elaborate implicit time-marching resolution of the equations. The enthalpy loss coefficients as well as the blade outlet flow angles are evaluated through open literature correlations. An efficient representation of the Craig-Cox loss coefficients and the Ainley-Mathieson outlet flow angle correlation brings the necessary empirical information for the velocity triangle computations. The computer code was validated against a high pressure turbine test case featuring multiple cooling flows. The results show the good capabilities of the turbine model using only standard correlations. The computed efficiency also shows the need to model the cooling losses. The low speed, low expansion rate results may finally indicate that the code accuracy would benefit from a correlation parametric identification such as the one led in the compressor case. [less ▲]

Detailed reference viewed: 150 (4 ULg)
Full Text
See detailA Quasi-One Dimensional Model for Axial Compressors
Adam, Olivier; Léonard, Olivier ULg

in Proceedings od the 17th ISABE Conference (2005, September)

The object of the present paper is to present a fast and reliable CFD tool that is able to simulate stationary and transient operations of multistage axial compressors. The computational domain is the ... [more ▼]

The object of the present paper is to present a fast and reliable CFD tool that is able to simulate stationary and transient operations of multistage axial compressors. The computational domain is the compressor flow path, using a row-by-row, quasi-one-dimensional representation of the machine at mid-span. This analysis tool is based on an adapted version of the Euler equations solved by a time-marching, finite-volume method. The basic Euler equations have been extended by including source terms expressing the blade-flow interactions. The source terms are determined using the velocity triangles for each blade row, at mid-span. The losses and deviations undergone by the fluid in each blade row are supplied by correlations. The resulting flow solver is a performance prediction tool based only on compressor geometry. It offers the possibility of exploring the entire characteristic map of a compressor before its construction. Its efficiency in terms of CPU time makes it possible to use it as a fast design tool by coupling it to an optimization algorithm. In this paper, this CFD tool (called Quads hereafter) has been applied to two test-cases. Calculated characteristic curves are presented and compared to experimental ones. A correlation tuning process is described for an undocumented family of blade profiles. [less ▲]

Detailed reference viewed: 97 (2 ULg)