Simulation of metal forming processes : Numerical aspects of contact and friction

Scientific conference (2003, January)

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the ... [more ▼]

During this presentation, two numerical methods for managing contact in large stresses/strains problems are described: the Lagrange Multipliers method (available in Cast3M - FE code used in LaCaN) and the penalty method (available in Metafor - FE code used at LTAS-MCT - University of Liège). Contact algorithms can be divided into three steps. The first one - the contact search - is purely geometric and answers the question: which nodes are currently in contact. Main problems and their solutions are discussed. The computation of the normal force is the second step. Non-penetration conditions are applied on the contact nodes. Finally, during the third step, a tangent force due to friction is applied when the nodes are sticking or sliding. Methods are compared in details in the case of metal forming processes. The penalty method seems to be more efficient when a large number of contact nodes are involved during the simulation. The system to be solved is smaller, the convergence is faster and curved analytical surfaces can be easily used for the tools. However, a good penalty coefficient can sometimes be hard to find. As a conclusion, numerical examples coming from Metafor are presented including skin-pass simulation, hydroforming of a tube and blade loss in a aeronautic engine. [less ▲]

Principes de diagnostic er de traitement des troubles vocaux

Scientific conference (2003, January)

Caractérisation et utilisation du micro-habitat du saumon atlantique (Salmo salar) selon la structure turbulente de l'écoulement

Scientific conference (2003)

Tous pouvoirs confondus

Scientific conference (2003)

L’astrobiologie

Scientific conference (2003)

Tuning of ruthenium N-heterocyclic carbene catalysts for olefin polymerisation and fine chemistry

Scientific conference (2003)

Rapport belge sur la propriété des sols

Scientific conference (2003)

Vers une politique de qualité, à quel prix ?

Scientific conference (2003)

Description de l'utilisation d'une base de données relative aux achats de produits alimentaires effectués par des ménages.

A current challenge: processing of bistatic STAP signals

Scientific conference (2003)

Optimal processing of STAP signals, its interpretations and its numerical requirements

Scientific conference (2003)

Airborne pulse-Doppler radar and early forms of radar space-time processing

Scientific conference (2003)

De l'utilité des miospores en prospection pétrolière

Scientific conference (2003)

Copropriété et servitudes

Scientific conference (2003)

Heavy metal hypersensitive mutants in Chlamydomonas reinhardtii.

Scientific conference (2002, December 16)

Traitements séquentiels dans l'acromégalie

Scientific conference (2002, December 13)

VALIDATION OF ENVISAT-1 LEVEL-2 PRODUCTS RELATED TO LOWER ATMOSPHERE O3 AND NOy CHEMISTRY BY A FTIR QUASI-GLOBAL NETWORK

Scientific conference (2002, December)

A coordinated action involving eleven stations of the ground-based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to ... [more ▼]

A coordinated action involving eleven stations of the ground-based Network for Detection of Stratospheric Change (NDSC) equipped with Fourier transform infrared (FTIR) instruments was conducted to contribute to the validation of the three atmospheric chemistry instruments onboard ENVISAT, that are MIPAS, SCIAMACHY and GOMOS. The target products for validation are total columns of O3, CH4, CO and some important NOy species (NO2, HNO3, NO) and the source gas N2O. Together the eleven stations cover the latitudes between 79 °N and 78°S, including polar, mid -latitude and subtropical and tropical locations. The goal is to contribute to the assessment of the data quality of the aforementioned ENVISAT instruments, from a quasi-global perspective. The period of intensive ground-based data collection for the benefit of the ENVISAT Validation Commissioning Phase that is dealt with in the present paper is July 15 to December 1, 2002. The FTIR network involved collected a data set corresponding to an equivalent of approximately 400 days of measurements; about three quarter of the data have already been submitted to the ENVISAT Calval database and are included in the present work. Unfortunately, the distribution of ENVISAT data has been slow and limited. Only a limited number of coincidences has been found for making data inter-comparisons. Therefore, the conclusions drawn in this paper are very preliminary and cover only a limited set of data products from SCIAMACHY only. Our findings up to now concerning the above mentioned target products are the following: (1) SCIAMACHY near infrared operational products (CO, CH4, N2O) have no scientific meaning yet, (2), the operational SCIAMACHY total vertical O3 column product derived in the ultraviolet window has undergone some improvements with changing versions of the processor(s) but it still underestimates the column by about 5 – 10 %, (3), the operational SCIAMACHY total vertical O3 column product derived in the visible window is unrealistically large, and (3), the operational NO2 total column product from SCIAMACHY seems to largely overestimate the real column, but very few coincidences and large dispersions of the data do inhibit any further conclusion at present. In a next phase, the same ground-based correlative data set will be exploited to further validate the ENVISAT data as soon as more and reprocessed data will be distributed. [less ▲]

Individualismo y sociedad

Scientific conference (2002, December)

Segun las mismas lienas que la critica de la escuela de Frankfurt, la conferencia expone como los nuevos "postmaterialisas" (Inglehart) son a la vez mas dispuestos a la democracia y la tolerancia pero al ... [more ▼]

Segun las mismas lienas que la critica de la escuela de Frankfurt, la conferencia expone como los nuevos "postmaterialisas" (Inglehart) son a la vez mas dispuestos a la democracia y la tolerancia pero al mismo tiempo, menos dispuestos a la solidaridad, lo que fragiliza precisamente la base misma del postmaterialismo [less ▲]

Exploration de l’administrateur central de la mémoire de travail au moyen de la TEP

Scientific conference (2002, December)

Séparation énantiomérique de substances médicamenteuses à l'aide de dérivés de cyclodextrines en électrophorèse capillaire en milieu non aqueux: effets synergiques de l'appariement d'ions

Scientific conference (2002, November 21)

Thyroïde et grossesse

Scientific conference (2002, November 13)

Selective encryption of uncompressed and compressed images

Scientific conference (2002, November 06)

Design of a proof of concept study in patients with prolactinoma intolerant to or resistant to treatment with dopamine agonists

Scientific conference (2002, November)

Le Secret des Géants

Scientific conference (2002, November)

Transformation et valorisation des sous-produits de dattes en Tunisie.

Scientific conference (2002, October 15)

Varicella zoster virus: a herpesvirus not like the others...

Scientific conference (2002, October)

Analyse de données longitudinales continues et applications

Scientific conference (2002, October)

Is the Hagberg Falling Number always linked to the a - amylase activity of wheat ?

Scientific conference (2002, September 25)

Among and within provenance variability for decay resistance of Larch wood to fungi

Scientific conference (2002, September 16)

Decay resistance of Larch wood was examined at the species, provenance and tree levels. To realise this study, 313 trees were harvested in 13 contrasting populations of different ages derived from 2 ... [more ▼]

Decay resistance of Larch wood was examined at the species, provenance and tree levels. To realise this study, 313 trees were harvested in 13 contrasting populations of different ages derived from 2 natural stands (France, Austria) and 4 provenance/progeny trials (Germany, Belgium, France and Great-Britain). The material includes 11 European, 1 japanese and 2 hybrid larch origins. [less ▲]

The Flesh-Eating Bacteria

Scientific conference (2002, September)

Inherent Modulation: a fast chopping method for nulling interferometry

Scientific conference (2002, August 28)

The reduction of the thermal background emission from the local and exo-zodiacal dust clouds is a critical element for the success of ESA's space mission, DARWIN. Internal modulation, a technique using ... [more ▼]

The reduction of the thermal background emission from the local and exo-zodiacal dust clouds is a critical element for the success of ESA's space mission, DARWIN. Internal modulation, a technique using fast signal chopping, isolating the planetary signal from these noise sources, was proposed by Mennesson and Mariotti (Icarus 128, 1997). In this paper, we investigate a modification to the implementation of internal modulation, which provides similar performance with a single detector and a greatly simplified optical layout: the number of beam combiners is reduced by a factor of about two. For example, a Robin Laurance six-telescope interferometer (Karlsson and Mennesson, Proc. SPIE 4006, 2000) can be implemented on five beam combiners instead of twelve. It is demonstrated that inherent modulation can be applied to all existing nulling configurations, including linear arrays. The principle of inherent modulation relies on two nulling interferometers using the same telescopes and beam combination with opposite phase shifts, some of them being different from 0 or pi. During operations, multiplexing between the two interferometers is performed, such that at any time only one interferometer is being used. Since the method lends itself for implementation with four-telescope linear arrays, inherent modulation would also be well suited for the detection of hot Jupiters with a ground-based nulling interferometer on the VLTI. [less ▲]

High-order, high-frequency methods for surface scattering problems

Scientific conference (2002, July 23)

Structural Fire Modelling. Where is the Frontier Nowadays?

Scientific conference (2002, July 11)

GENIE, the Ground-based European Nulling Interferometry Experiment

Scientific conference (2002, June 27)

Within the frame of the Darwin program, the European Space Agency and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called Darwin-GENIE, using the Very ... [more ▼]

Within the frame of the Darwin program, the European Space Agency and the European Southern Observatory (ESO) intend to build a ground-based technology demonstrator called Darwin-GENIE, using the Very Large Telescope Interferometer (VLTI). The main objective of GENIE is to gain experience in the manufacture and operation of a nulling interferometer representative of the ESA IRSI-Darwin space mission. GENIE will prepare the Darwin science programme through a systematic search for exo-zodiacal dust clouds around Darwin candidate targets. GENIE also aims to perform Darwin related science including the detection of low-mass companions (if possible, hot Jupiters) around nearby stars. The prospective performances of some candidate configurations are presented in this paper. [less ▲]

Configurations and modulation schemes trade-off (invited)

Scientific conference (2002, June 05)

During the preliminary phase A of GENIE, a number of interferometric configurations have been studied, in the cases of exo-zodiacal cloud and hot Jupiter detection. Their expected performances have been ... [more ▼]

During the preliminary phase A of GENIE, a number of interferometric configurations have been studied, in the cases of exo-zodiacal cloud and hot Jupiter detection. Their expected performances have been computed in light of the measured or expected performances of the VLTI sub-systems. A simple Bracewell nulling interferometer, formed of two Unit Telescopes and working in the L' or N bands, has been identified as a good candidate configuration for exo-zodiacal cloud detection. External or internal chopping, fringe tracking and amplitude matching will be critical issues for this configuration. In the case of hot Jupiter detection, a double Bracewell with internal modulation in the L' band seem well appropriate, and should allow to carry out low resolution spectroscopy on a few bright exoplanets. The basic assumptions and computations which have lead to these candidate configurations will be described in this talk. [less ▲]

Hirsutisme et hyperthrycose

Scientific conference (2002, June 04)

L'hypertrycose est un ecause fréquente de consultation chez les femmes, et souvent invalidante sur le plan psychologique. L'objet de cette présentation est de différencier l'hirsutisme (de cause ... [more ▼]

L'hypertrycose est un ecause fréquente de consultation chez les femmes, et souvent invalidante sur le plan psychologique. L'objet de cette présentation est de différencier l'hirsutisme (de cause endocrinienne) de l'hypertycose (constitutionnelle). Nous rappelons la sémiologie, la mise au point biologique, la physiopathologie et les différentes explorations de l'hyperandrogénie, qui déterminent ube prise en charge appropriée. [less ▲]

La maladie de Cushing

Scientific conference (2002, June)

Etude des substrats cérébraux du fonctionnement exécutif au moyen de l'imagerie cérébrale

Scientific conference (2002, June)

La prise en charge cognitive dans les stades débutants de la maladie d'Alzheimer

Scientific conference (2002, May 27)

Rappresentazioni sociali del cibo e del corpo in adolescenza. Un approccio multi-metodologico

Scientific conference (2002, May 24)

GENIE, the Ground-based European Nulling Interferometry Experiment

Scientific conference (2002, May 15)

L’instrument GENIE (Ground-based European Nulling Interferometer Experiment), projet co-financé par l’ESA et l’ESO, est un interféromètre en frange noire qui sera installé vers mi-2006 sur le site du VLTI ... [more ▼]

L’instrument GENIE (Ground-based European Nulling Interferometer Experiment), projet co-financé par l’ESA et l’ESO, est un interféromètre en frange noire qui sera installé vers mi-2006 sur le site du VLTI. Cet instrument, actuellement en phase de définition, sera avant tout un démonstrateur technologique pour la mission spatiale Darwin. Mais il permettra aussi de détecter des disques de poussière zodiacale autour d’étoiles proches, de faire la spectroscopie des plus brillants d’entre eux, et probablement de détecter pour la première fois le rayonnement thermique de certains Jupiters chauds. Dans cet exposé, je discuterai les performances attendues de GENIE en fonction de la configuration instrumentale choisie, aussi bien pour la détection de disques que d’exoplanètes. [less ▲]

Rééducation cognitive des patients Alzheimer en début d'évolution

Scientific conference (2002, May 08)

Recyclages et séminaires fiscaux annuels

Scientific conference (2002, May)

Nature morte et poésie

Scientific conference (2002, April 22)

Les substrats cérébraux du fonctionnement exécutif: étude en imagerie cérébrale et dans la maladie d'Alzheimer

Scientific conference (2002, April)

Qu’est-ce qu’un éditeur ? Naissance de la fonction éditoriale moderne

Scientific conference (2002, March 02)

L’histoire belge de la médecine des populations …

Scientific conference (2002, March)

Phénomènes de violence et débordements autour du sport: la réponse institutionnelle

Scientific conference (2002, March)

Brownian Dynamics in a Turbulent Channel Flow

Scientific conference (2002, February)

Le Gigantisme : Un mystère élucidé

Scientific conference (2002, January 22)

L’édition en Belgique d’hier à aujourd’hui

Scientific conference (2002, January 11)