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See detailA perturbation method for computing field distortions due to conductive regions with h-conform magnetodynamic finite element formulations
Dular, Patrick ULg; V Sabariego, Ruth ULg

in IEEE Transactions on Magnetics (2007), 43(4), 1293-1296

A method for solving eddy current problems in two separate steps is developed for global-local analyses with h-conform finite element formulations. An unperturbed problem is first solved in a global mesh ... [more ▼]

A method for solving eddy current problems in two separate steps is developed for global-local analyses with h-conform finite element formulations. An unperturbed problem is first solved in a global mesh excluding additional conductive regions. Its solution gives the sources for a sequence of other problems, perturbed by adding conductive regions. Each problem only requires a new adapted mesh of a local region. The way the local problems and their sources are defined leads to a significant speedup of parameterized analyses, e.g., in optimization and sensitivity analyses. [less ▲]

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See detailA perturbation method for the 3D finite element modeling of electrostatically driven MEMS
Boutaayamou, Mohamed ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg

in Sensors (2008), 8(2), 994-1003

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving ... [more ▼]

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving conductors. The computation is split in two steps. First, an unperturbed problem (in the absence of certain conductors) is solved with the conventional FE method in the complete domain. Second, a perturbation problem is solved in a reduced region with an additional conductor using the solution of the unperturbed problem as a source. When the perturbing region is close to the original source field, an iterative computation may be required. The developed procedure offers the advantage of solving sub-problems in reduced domains and consequently of benefiting from different problem-adapted meshes. This approach allows for computational efficiency by decreasing the size of the problem. [less ▲]

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See detailA Perturbation Method for the 3D Finite Element Modeling of Electrostaticaly Driven MEMS
Boutaayamou, Mohamed ULg; V Sabariego, Ruth ULg; Dular, Patrick ULg

in Proceedings of the 8th International Conference on Thermal, Mechanical and Multiphysics Simulation and Experiments in Micro-Electronics and Micro-Systems (2007, April)

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving ... [more ▼]

In this paper, a finite element (FE) procedure for modeling electrostatically actuated MEMS is presented. It concerns a perturbation method for computing electrostatic field distortions due to moving conductors. The computation is split in two steps. First, an unperturbed problem (in the absence of certain conductors) is solved with the conventional FE method in the complete domain. Second, a perturbation problem is solved in a reduced region with an additional conductor using the solution of the unperturbed problem as a source. When the perturbing regions are close to the original source field, an iterative computation may be required. The developed procedure offers the advantage of solving sub-problems in reduced domains and consequently of benefiting from different problem-adapted meshes. This approach allows for computational efficiency by decreasing the size of the problem. [less ▲]

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See detailA perturbation method for the T-Ω geometric eddy-current formulation
Codecasa, Lorenzo; Dular, Patrick ULg; Specogna, Ruben et al

in IEEE Transactions on Magnetics (2010), 46(8), 3045-3048

A perturbation method for the T-Ω geometric formulation to solve eddy-current problems is introduced. The proposed formulation is applied to the feasibility design of a nondestructive evaluation device ... [more ▼]

A perturbation method for the T-Ω geometric formulation to solve eddy-current problems is introduced. The proposed formulation is applied to the feasibility design of a nondestructive evaluation device suitable to detect “long” longitudinal flaws in hot steel bars. [less ▲]

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See detailPerturbation methods for the determination of the statistical response of nonlinear Volterra systems
Denoël, Vincent ULg; Carassale, Luigi

in Proceedings of the Eurodyn 2014 Conference (2014)

The point-like quasi-steady aerodynamic loading in a turbulent flow is formally expressed as a function of the squared relative velocity between the fluid and the investigated structure. The three major ... [more ▼]

The point-like quasi-steady aerodynamic loading in a turbulent flow is formally expressed as a function of the squared relative velocity between the fluid and the investigated structure. The three major terms governing the low-order statistics of the response are known to be related to the average loading, the linear turbulent loading and the aerodynamic damping. The three other terms in the loading, namely the quadratic turbulence term, the parametric velocity feedback term and the squared velocity term, may significantly affect the higher order statistical cumulants of the response. These latter two sources of fluid-structure interaction are usually disregarded, by lack of efficient simulation tools, except a Monte Carlo simulation of the nonlinear equation. In this paper, we provide a formal analysis of the complete nonlinear model, including thus all six terms, but mainly focusing on the importance of the two nonlinear coupling terms of the loading. Closed form solutions of the response are derived for a second-order Volterra model of this problem, under the assumption of different timescales in the loading and in the structural behavior. Two major outcomes of the analysis are, on the one hand, that the squared structural velocity term has no influence on the cumulants of the response up to order 4 and, on the other hand, that the parametric velocity feedback acts as a reduction of the non Gaussianity of the response. [less ▲]

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See detailPerturbation of actin dynamics induces NF-kappa B activation in myelomonocytic cells through an NADPH oxidase-dependent pathway
Kustermans, Gaëlle ULg; El Benna, Jamel; Piette, Jacques ULg et al

in Biochemical Journal (2005), 387(Pt 2), 531-540

Although several reports showed the effect of compounds disrupting microtubules on NF-kappa B (nuclear factor kappa B) activation, nothing is known about agents perturbing actin dynamics. In the present ... [more ▼]

Although several reports showed the effect of compounds disrupting microtubules on NF-kappa B (nuclear factor kappa B) activation, nothing is known about agents perturbing actin dynamics. In the present study, we have shown that actin cytoskeleton disruption induced by actin-depolymerizing agents such as cytochalasin D and latrunculin B and actin-polymerizing compounds such as jasplakinolide induced NF-kappa B activation in myelomonocytic cells. The transduction pathway involved the I kappa B (inhibitory kappa B) kinase complex and a degradation of I kappa B alpha. We have shown that NF-kappa B activation in response to the perturbation of actin dynamics required reactive oxygen species. as demonstrated by the effect of antioxidants. Actin cytoskeleton disruption by cytochalasin D induced O-2(-) release from human monocytes, through the activation of the NADPH oxidase, as confirmed by the phosphorylation and by the membrane translocation of p47(phox). NF-kappa B activation after actin cytoskeleton disruption could be physiologically relevant during monocyte activation and/or recruitment into injured tissues, where cellular attachment, migration and phagocytosis result in cyclic shifts in cytoskeletal organization and disorganization. [less ▲]

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See detailA perturbation technique for Finite Element Modelling of Piezoelectric Vibrations in Travelling Wave Ultrasonic Motors
Ledinh, T.; Dular, Patrick ULg; Gyselinck, J. et al

in Proceedings of the second international conference on advanced computational methods in engineering, ACOMEN 2002 (2002)

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See detailPerturbation technique for the finite element modelling of differential probes in non-destructive eddy-current testing
V Sabariego, Ruth ULg; Dular, Patrick ULg

in IET Science, Measurement & Technology (2007), 1(1), 25-29

The paper deals with a new finite element scheme for non-destructive eddy-current testing (ECT) problems involving multiply connected test pieces and differential probes. It concerns a perturbation ... [more ▼]

The paper deals with a new finite element scheme for non-destructive eddy-current testing (ECT) problems involving multiply connected test pieces and differential probes. It concerns a perturbation technique applied to the magnetodynamic h - phi formulation. The unperturbed field (in the absence of the flaw) is conventionally computed in the complete domain. The source of the perturbation problem is then determined by the projection of the unperturbed field in a relatively small region around the defect, the optimum size of which depends on the working frequency. The discretisation of this reduced domain is well adapted to the size of the defect and chosen independently of the dimensions of the excitation probe and the specimen under study. At a discrete level, the voltage change is efficiently computed by integration only over the defect and a layer of elements in the reduced domain that touches the defect's boundary. The accuracy of the proposed perturbation model is illustrated by comparison of the results obtained for different dimensions of the reduced domain with those achieved in the conventional way. The considered test case involves a differential probe scanning the outer surface of a metal tube for the detection of through-wall cracks. [less ▲]

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See detailA perturbation technique for the finite element modelling of non-destructive eddy current testing
V Sabariego, Ruth ULg; Dular, Patrick ULg

in Electromagnetic Fields in Mechatronics, Electrical and Electronic Engineering (2006)

This paper deals with a new 3D finite element scheme for nondestructive eddy-current testing (ECT) problems. It concerns a perturbation technique applied to the magnetodynamic h- φ formulation. The ... [more ▼]

This paper deals with a new 3D finite element scheme for nondestructive eddy-current testing (ECT) problems. It concerns a perturbation technique applied to the magnetodynamic h- φ formulation. The unperturbed field (in the absence of the flaw) is computed conventionally in the complete domain. The source of the perturbation problem is determined by the projection of the unperturbed field in a relatively small region around the defect that depends on the work frequency. The discretisation of this reduced domain is adapted to the size of the defect and independent of the discretisation of the complete domain. The impedance change is computed by integrating only over the defect and a layer of elements in the reduced domain that touch its boundary. As test case, we consider the second eddy current benchmark problem proposed by the WFNDEC. It involves a pancake coil scanning the inner surface of a metal tube for the detection of flaws on the outer surface. [less ▲]

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See detailPerturbations de la phosphorylation oxydative : réponses protéomiques et conséquences métaboliques
Mathy, Grégory ULg

Doctoral thesis (2009)

La phosphorylation oxydative et ses partenaires privilégiés, que sont les voies métaboliques énergétiques principales, sont finement régulés au niveau thermodynamique en vertu de la loi d’action des ... [more ▼]

La phosphorylation oxydative et ses partenaires privilégiés, que sont les voies métaboliques énergétiques principales, sont finement régulés au niveau thermodynamique en vertu de la loi d’action des masses. Ces processus de régulations enzymatiques s’accompagnent cependant de « soupapes » de sécurité qui permettent, le cas échéant, de maintenir de manière optimale la bonne opération de l’ensemble de ce système et donc d’assurer une balance metabolique adequate entre l’offre et la demande. Par une approche de protéomique comparée, nous avons étudiés les effets de ces différents types de stress tant au niveau mitochondrial que cellulaire afin de mettre en évidence d’éventuelles adaptations initiées par la cellule en réponse à ces perturbations Dans la première partie nous avons etudie les effets de l’oxydase alternative sur le protéome mitochondrial et cellulaire. La première etude consiste en une création de la fonction AOX au niveau mitochondrial dans un organisme modèle ne l’exprimant pas naturellement : Saccharomyces cerevisiae. Deux approches protéomiques ont été utilisees, à savoir le 2D DIGE et le SILAC. La seconde étude concernant AOX consiste en l’analyse des effets d’une perte de fonction de la protéine obtenue par ARN interférence chez l’algue unicellulaire Chlamydomonas reinhardtii. La seconde partie de notre travail sera consacrée à l’étude des modifications protéomiques accompagnant l’initiation de la thermogenèse non frissonnante ainsi que l’acclimatation au froid au niveau du tissu adipeux brun. Cette étude à été réalisée chez le rat et chez la souris. Les effets de l’acclimatation au froid chez des souris UCP-1 KO ont ete aussi étudiés et comparés aux effets chez des souris normales. [less ▲]

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See detailPerturbations endocriniennes et polluants environnementaux
Charlier, Corinne ULg

in Revue Médicale de Liège (2006)

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See detailPerturbations endocriniennes liées aux polluants environnementaux
Charlier, Corinne ULg

Conference (2009)

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See detailPerturbations neuropsychiques graves chez un jeune adolescent soumis à une thérapeutique endocrinienne
Servais, Jean-François; Mormont, Christian ULg; Bostem, F. et al

in Acta Psychiatrica Belgica (1976), 76(1), 97-106

After a treatment based on the administration of gonadotropic drugs, aimed at reduced school difficulties and caracterial difficulties by a premature onset of puberty, a young male aged 13 1/2 presents: 1 ... [more ▼]

After a treatment based on the administration of gonadotropic drugs, aimed at reduced school difficulties and caracterial difficulties by a premature onset of puberty, a young male aged 13 1/2 presents: 1 degree somatic anomalies; 2 degrees increase of intellectual, affective and behavioral troubles; 3 degrees perturbations of EEG prophiles; 4 degrees organicity tests significantly disturbed. The interruption of treatment (4 years of observation) was followed by a progressive remission, however heterogenous, of all initial troubles. The observation underlines the dangers of utilising these treatments in a pre-puberty boy. [less ▲]

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See detailPerturbations of the Earth evolutions by intense energetics particule precipitations
Gérard, Jean-Claude ULg; Hauglustaine, Didier A.

Report (1987)

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See detailPerturbations récentes dans le Bassin du Congo : Contribution de l’anthracologie à une restitution paléoenvironnementale
Morin-Rivat, Julie ULg; Hubau, Wannes; Gillet, Jean-François et al

Poster (2012, May 22)

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See detailPerturbative evolution and Regge behaviour
Cudell, Jean-René ULg; Donnachie, A.; Landshoff, P. V.

in Physics Letters B (1999), 448

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See detailPerturbative QCD
Ivanov, Igor ULg

in Naumov, Dmitry; Vall, Alexander (Eds.) Proceedings of the X Baikal Summer School On Physics Of Elementary Particles And Astrophysics (2011)

These lectures, intended mainly for undergraduates, contain a very short introduction into perturbative QCD. We introduce the QCD lagrangian, outline how QCD is quantized and renormalized, and as an ... [more ▼]

These lectures, intended mainly for undergraduates, contain a very short introduction into perturbative QCD. We introduce the QCD lagrangian, outline how QCD is quantized and renormalized, and as an example describe the calculation of the elastic two-gluon scattering. We then discuss the physics behind the parton model of hadron collisions, with the important issues of the infrared safety and factorization. We end with a short description of how different hadronic final states are searched for and studied at hadron colliders. [less ▲]

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See detailPerturbative QCD corrections to the soft pomeron
Cudell, Jean-René ULg; Margolis, B.

in MRST Meeting 1992 (1992)

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