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See detailParallel Computing and Localization Techniques for Faster Power System Dynamic Simulations
Aristidou, Petros ULg; Van Cutsem, Thierry ULg

in Proceedings of Cigre 2014 Belgium Conference (2014, March 13)

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. This type of simulation is essential when the system is operating close to its stability ... [more ▼]

Dynamic simulation studies are used to analyze the behavior of power systems after a disturbance has occurred. This type of simulation is essential when the system is operating close to its stability limits or its behavior is dictated by complex control and protection schemes modifying its trajectory. These simulations can be computationally very demanding, especially if performed over a time interval of several minutes. In this paper, new shared- memory parallel computing techniques to increase the performance of large-scale power system dynamic simulations are described. The algorithms presented achieve this by utilizing the parallel processing resources available in modern, inexpensive, multi-core machines. In addition, the localized response of power systems after a disturbance is exploited to further accelerate simulations without decreasing accuracy. The medium-scale model of a real power system and a realistic large-scale test system have been used for the performance evaluation of the proposed methods. [less ▲]

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See detailA parallel computing model for the acceleration of a finite element software
Moto Mpong, Serge; de Montleau, Pierre; Godinas, André et al

in Arabnia, H. R. (Ed.) Proceedings of the International Conference on Parallel and Distributed Processing Techniques and Applications (2002)

This paper presents the parallelization model used for the non-linear finite element software LAGAMINE. The proposed model is based on the use of a coarse grain approach for the parallelization of the ... [more ▼]

This paper presents the parallelization model used for the non-linear finite element software LAGAMINE. The proposed model is based on the use of a coarse grain approach for the parallelization of the assembly of the stiffness matrix. For the solver of the generated linear problem, we used a parallel direct solver of Gauss type. Finally, we present a discussion of the results of our approach on an example of depp drawing. [less ▲]

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See detailParallel detection of antigen-specific T-cell responses by multidimensional encoding of peptide-Major Histocompatibility Complexes
Reker Hadrup, Sine; Bakker, Arnold H; Shu, Chengyi J. et al

in Nature Methods (2009), 6((7)), 520-526

Abstract The use of fluorescently labeled MHC multimers has become an essential technique for the analysis of disease- and therapy-induced T cell immunity. While classical MHC multimer analyses are well ... [more ▼]

Abstract The use of fluorescently labeled MHC multimers has become an essential technique for the analysis of disease- and therapy-induced T cell immunity. While classical MHC multimer analyses are well-suited for the detection of immune responses against a few epitopes, limitations on patient sample size preclude a comprehensive analysis of T cell immunity. To address this issue, we have developed a combinatorial encoding strategy that allows the parallel detection of a multitude of different T cell populations within a single sample. Detection of antigen-specific T cells from peripheral blood by combinatorial encoding is as efficient as detection with conventional PE labeled multimers, but results in a significantly increased sensitivity, and most importantly, allows comprehensive screens to be performed on patient material. Proof of principle for the feasibility of large-scale screening of patient material was obtained by analysis of HLA-A3 restricted T cell responses against known and potential melanoma-associated antigens in peripheral blood from melanoma patients. 2 [less ▲]

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See detailParallel measurements of formaldehyde (H2CO) at the Jungfraujoch station: preliminary FTIR results and first comparison with Max-DOAS data
Franco, Bruno ULg; Mahieu, Emmanuel ULg; Van Roozendael, Michel et al

Scientific conference (2013, October 17)

In the framework of the NORS project, a retrieval strategy for formaldehyde (H2CO) is currently under development, using measurements from ground-based high-resolution FTIR solar spectra recorded at the ... [more ▼]

In the framework of the NORS project, a retrieval strategy for formaldehyde (H2CO) is currently under development, using measurements from ground-based high-resolution FTIR solar spectra recorded at the NDACC high altitude station of the Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580m a.s.l.). According to the preliminary results, our FTIR retrieval strategy based on Tikhonov regularization has proven able to make an improvement in the process of fitting the H2CO feature within the 2833.070 – 2833.350 cm-1 microwindow from Jungfraujoch solar spectra, compared to a simple scaling. Furthermore, the retrieved total columns present a seasonal cycle averaged over 2005 – 2013 in agreement with preliminary results from UV-visible MAX-DOAS observations, ACE-FTS occultation measurements and simulations from the IMAGES and GEOS-CHEM models. However, FTIR H2CO abundances appear to be underestimated during summertime, with respect to the other data sets. In order to solve this issue, further experiments are planned. [less ▲]

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See detailParallel propagating electromagnetic solitons and oscillitons in space plasmas and in relativistic electron-positron plasmas
Verheest, F.; Cattaert, Tom ULg

in Physica Scripta (2005), T116

An overview is given of methods to study weak and strong nonlinear modes in multispecies plasmas, with a discussion of how they correspond (or not) for phenomena at not too strong amplitudes. Reductive ... [more ▼]

An overview is given of methods to study weak and strong nonlinear modes in multispecies plasmas, with a discussion of how they correspond (or not) for phenomena at not too strong amplitudes. Reductive perturbation analysis leads for weak nonlinear waves to several well known nonlinear evolution equations. In contrast, strong nonlinear phenomena are dealt with by immediately looking for stationary solutions of the model equations. While this works well for electrostatic modes via the Sagdeev pseudopotential technique, large amplitude, parallel propagating solitary electromagnetic waves occur as oscillitons, for which the correct nonlinear evolution equation is still lacking. Electromagnetic modes in (relativistic) electron-positron plasmas are an exception, in that they give pure solitons, both at large and smaller nonlinear amplitudes. The behaviour of the wave magnetic field is expressed through an energy integral that involves the Mach number of the structure, thus yielding the limits on the allowable Mach numbers and soliton amplitudes. [less ▲]

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See detailThe paralogous salivary anti-complement proteins IRAC I and IRAC II encoded by Ixodes ricinus ticks have broad and complementary inhibitory activities against the complement of different host species.
Schroeder, Hélène ULg; Daix, Virginie; Gillet, Laurent ULg et al

in Microbes & Infection (2007), 9(2), 247-50

Several observations suggest that inhibition of the host complement alternative pathway by Ixodes tick saliva is crucial to achieve blood feeding. We recently described two paralogous anti-complement ... [more ▼]

Several observations suggest that inhibition of the host complement alternative pathway by Ixodes tick saliva is crucial to achieve blood feeding. We recently described two paralogous anti-complement proteins called Ixodes ricinus anti-complement (IRAC) proteins I and II co-expressed in I. ricinus salivary glands. Phylogenetic analyses suggested that these sequences were diversifying by a process of positive Darwinian selection, possibly leading to molecules with different biological properties. In the present study, we tested the hypothesis that each paralogue may have different inhibitory activities against the complement of different natural host species, thereby contributing to broaden the host range of I. ricinus ticks. IRAC I and IRAC II were tested against the complement of eight I. ricinus natural host species (six mammals and two birds). The results demonstrate that IRAC I and IRAC II have broad and complementary inhibition activities against the complement of different host species. This report is the first description of paralogous anti-complement molecules encoded by a pathogen with broad and complementary inhibitory activities against the complement of different host species. [less ▲]

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See detailParalysie non traumatique du nerf interosseux antébrachial postérieur liée à la pratique du vélo tout-terrain
WANG, François-Charles ULg; GOFFINET, Estelle ULg

in Lettre du Neurologue (La) : le Courrier du Spécialiste (2010)

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See detailParalysie non traumatique du nerf interosseux antébrachial postérieur liée à la pratique du VTT
Goffinet, Estelle; Zeevaert, Bernard; Claes, Frédérique et al

in Journal de Traumatologie du Sport (2004)

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See detailParalysie vélo-palatine et oculomotrice d'apparition brutale : une forme particulière de polyradiculonévrite
Franckart, Geneviève; Fakif, K.; Trippaerts, Marc ULg et al

in Comptes Rendus des Journées Annuelles de la Société Belge de Pédiatrie (1990)

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See detailLes paralysies du nerf moteur oculaire commun chez l'enfant: a propos d'une observation de tumeur germinale hypophysaire.
Kalenga, Mbu; COLLIGNON, Nathalie ULg; ANDRIS, Cécile ULg et al

in Bulletin de la Société Belge d'Ophtalmologie (2011), (318), 31-6

PURPOSE: Third cranial nerve palsies are unfrequent in childhood and adolescence and are most often congenital. The association of sellar germ cell tumor and ophthalmoplegia is considered as being very ... [more ▼]

PURPOSE: Third cranial nerve palsies are unfrequent in childhood and adolescence and are most often congenital. The association of sellar germ cell tumor and ophthalmoplegia is considered as being very rare at this age. CASE REPORT: A 11-year-old young girl was examined in emergency with a third left cranial nerve partial palsy associated with one- year duration history of hypopituitarism with insipid diabetes and growth retardation. Cerebral IRM revealed a tumor of the pituitary gland. In histopathological examination of pituitary gland biopsies, lesions were compatibles with a sellar germ cell tumor. CONCLUSION: Although they are most often of a congenital nature, third cranial nerve palsies in childhood may be secondary to other causes that should be always taken in mind. When they are secondary to a sellar tumor and according to the clinical presentation and the IRM, the histopahological examination of biopsies is mandatory to have a precise diagnosis. [less ▲]

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See detailParamagnetic nanoparticles as potential MRI contrast agents: characterization, NMR relaxation, simulations and theory
Quoc Lam Vuong; Van Doorslaer, Sabine; Bridot, Jean-Luc et al

in MAGNETIC RESONANCE MATERIALS IN PHYSICS BIOLOGY AND MEDICINE (2012), 25(6), 467-478

Paramagnetic nanoparticles, mainly rare earth oxides and hydroxides, have been produced these last few years for use as MRI contrast agents. They could become an interesting alternative to iron oxide ... [more ▼]

Paramagnetic nanoparticles, mainly rare earth oxides and hydroxides, have been produced these last few years for use as MRI contrast agents. They could become an interesting alternative to iron oxide particles. However, their relaxation properties are not well understood. Magnetometry, H-1 and H-2 NMR relaxation results at different magnetic fields and electron paramagnetic resonance are used to investigate the relaxation induced by paramagnetic particles. When combined with computer simulations of transverse relaxation, they allow an accurate description of the relaxation induced by paramagnetic particles. For gadolinium hydroxide particles, both T (1) and T (2) relaxation are due to a chemical exchange of protons between the particle surface and bulk water, called inner sphere relaxation. The inner sphere is also responsible for T (1) relaxation of dysprosium, holmium, terbium and erbium containing particles. However, for these latter compounds, T (2) relaxation is caused by water diffusion in the field inhomogeneities created by the magnetic particle, the outer-sphere relaxation mechanism. The different relaxation behaviors are caused by different electron relaxation times (estimated by electron paramagnetic resonance). These findings may allow tailoring paramagnetic particles: ultrasmall gadolinium oxide and hydroxide particles for T (1) contrast agents, with shapes ensuring the highest surface-to-volume ratio. All the other compounds present interesting T (2) relaxation performance at high fields. These results are in agreement with computer simulations and theoretical predictions of the outer-sphere and static dephasing regime theories. The T (2) efficiency would be optimum for spherical particles of 40-50 nm radius. [less ▲]

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See detailParamagnetic reentrance of ac screening: Evidence of vortex avalanches in Pb thin films
Silhanek, Alejandro ULg; Raedts, S.; Moshchalkov, V. V.

in Physical Review. B : Condensed Matter (2004), 70(14),

We have studied the influence of a square array of pinning centers on the dynamics of vortex avalanches in Pb thin films by means of ac- and dc-magnetization measurements. Close to the superconducting ... [more ▼]

We have studied the influence of a square array of pinning centers on the dynamics of vortex avalanches in Pb thin films by means of ac- and dc-magnetization measurements. Close to the superconducting transition T-c, the commensurability between the vortex lattice and the pinning array leads to the well known local increments of the critical current. As temperature T decreases, matching features progressively fade out and eventually disappear. Further down in temperature, vortex avalanches develop and dominate the magnetic response. These avalanches manifest themselves as jumps in the dc magnetization and produce a lower ac shielding, giving rise to a paramagnetic reentrance in the ac screening chi(')(T). Within the flux-jump regime, two subregimes can be identified. Close to the boundary where vortex avalanches develop, the field separation between consecutive jumps follows the periodicity of the pinning array and a field- and temperature-dependent screening is observed. In this regime, the response also depends on frequency f in agreement with theoretical models for magnetothermal instabilities. At low enough temperatures and fields, the screening saturates to a constant value independent of T, H, and f, where jumps are randomly distributed. We have also found that vortex instabilities occupy a larger portion of the H-T diagram in patterned samples than in films without nanoengineered pinning sites. Finally, we discuss the possible origin of the vortex avalanches and compare our results with previous experimental and theoretical studies. [less ▲]

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See detailParameter estimation and structural model updating using modal methods in the presence of nonlinearity
Golinval, Jean-Claude ULg

Conference given outside the academic context (2009)

Detailed reference viewed: 38 (7 ULg)
See detailParameter estimation in biochemical reaction networks: An observer-based approach
Fey, Dirk; Bullinger, Eric ULg

Conference (2008, March 27)

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See detailParameter estimation in kinetic reaction models using nonlinear observers is facilitated by model extensions
Fey, Dirk ULg; Findeisen, Rolf; Bullinger, Eric ULg

in 17th IFAC World Congress, Seoul, Korea (2008)

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See detailParameter estimation using slug tests : application to a heat injection and storage experiment
Vandenbohede, Alexander; Louwyck, Andy; Daoudi, Moubarak et al

Poster (2011, September 19)

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See detailParameter identification and shape/process optimization in metal forming simulation
Kleinermann, J. P.; Ponthot, Jean-Philippe ULg

in Journal of Materials Processing Technology (2003), 139(1-3), 521-526

Nowadays, computer simulations of metal forming processes using the finite element method (FEM) have reached some level of maturity. The purpose of inverse problems is to determine the simulation input ... [more ▼]

Nowadays, computer simulations of metal forming processes using the finite element method (FEM) have reached some level of maturity. The purpose of inverse problems is to determine the simulation input data for one or more of these forming processes, leading to a desired result. The first example is called parameter identification. This consists in evaluating the material parameters for material behavior laws that would lead to the most accurate model, minimizing the difference between experimental results and the corresponding FEM simulation. The second example is initial geometry and tool shape design, consisting in determining the initial shape of the specimen and/or the shape of the forming tools, in order to provide the desired final geometry after the forming process. Both inverse problem examples can be formulated as optimization problems. In this paper, the authors propose to solve these optimization problems with different non-linear optimization methods and to compare their efficiency. (C) 2003 Elsevier Science B.V. All rights reserved. [less ▲]

Detailed reference viewed: 29 (2 ULg)