Publications

2000

• Resource-bounded relational reasoning: induction and deduction through stochastic matching
  
  • Sebag Michèle
  • Rouveirol Céline
  Machine Learning, Springer Verlag, 2000, 38 (1-2), pp.41-62. One of the obstacles to widely using first-order logic languages is the fact that relational inference is intractable in the worst case. This paper presents an any-time relational inference algorithm: it proceeds by stochastically sampling the inference search space, after this space has been judiciously restricted using strongly-typed logic-like declarations. We present a relational learner producing programs geared to stochastic inference, named STILL, to enforce the potentialities of this framework. STILL handles examples described as definite or constrained clauses, and uses sampling-based heuristics again to achieve any-time learning. Controlling both the construction and the exploitation of logic programs yields robust relational reasoning, where deductive biases are compensated for by inductive biases, and vice versa. (10.1023/A:1007629922420)
  DOI : 10.1023/A:1007629922420
• Intelligent modelling of woven materials
  
  • Zarka Joseph
  • Doux Thierry
  , 2000.
• Optimal design of a beam with a direct link to CAD
  
  • Zarka J.
  • Hablot J. M.
  , 2000. No abstract provided
• Quelques exemples de vibrations et d'instabilité induites par le frottement
  
  • Nguyen Q. S.
  , 2000. No abstract provided
• Intelligent optimal design of naval structures: is it possible ?
  
  • Zarka J.
  , 2000. No abstract provided
• Percolation mécanique'' : pertinence des modèles classiques en viscoélasticité linéaire et nouvelles approches
  
  • Bornert Michel
  • Aussant F.
  • Zaoui A.
  , 2000. No abstract provided
• On the role of fluids in the cracks of elastic materials
  
  • Feraille Fresnet Adélaïde
  • Bui Huy Duong
  • Ehrlacher Alain
  , 2000, pp.53-64.
• Field Data vs. Theoretical Model to Quantify Drilling Efficiency and Disruption
  
  • Putot Claude
  • Perreau Philippe
  • Constantinescu Andrei
  SPE Drilling and Completion, Society of Petroleum Engineers, 2000, 15, pp.118-124. Mechanical and kinematics data at the bit have been collected during drilling operations and organized to identify optimal drilling efficiency. Transitional conditions towards abnormal behavior have been distinguished. Normal drilling is usually characterized by regular linear relationships between global control variables at the bit, which approximately correspond to an up scaling of a local Mohr Coulomb type failure mechanism of the rock. Most of our experimental data confirm this classical disposition. However, considerable departure from these relationships is noted, especially when there is BHA resonance or when there is partial balling at the bit. The field tests presented here allows us to verify classical theory and to draw up new guidelines for behavior in non- optimal or dangerous, evolving operating conditions, such as those that occur under poor cleaning conditions. The main features of a mechanical structuring model involving transition towards low efficiency conditions are presented, and it is shown how this model confirms our interpretation of field data. The model couples the drillability of rock and the general dynamics of the bit in an original and synthetic way. It makes it possible to understand and test the sensitivity of bit response to variables such as "weight on hook", torque on the drillstring and flow rate of the fluid. (10.2118/50579-MS)
  DOI : 10.2118/50579-MS
• A plasticity model for discontinua
  
  • Leroy Yves
  • Sassi William
  , 2000, pp.77-107. This article is concerned with the development and application of a simple continuum theory for rocks that may contain both randomly as well as preferentially oriented plane discontinuity surfaces. The theory stipulates that displacement discontinuities are independently activated on these surfaces as soon as an appropriate yield criterion is fulfilled; these displacement jumps account for the irreversible, ‘plastic’ part of the bulk deformation. In stress space, the critical conditions for the activation of discontinuous slip or opening displacements define an overall yield envelope that could be initially anisotropic, reflecting for example a weakness of certain orientations due to pre-existing joint sets. For the yield conditions studied in this paper, essentially a Coulomb-type friction law and a simple fracture opening condition, the inferred stress-strain response under typical triaxial loading conditions reveals the sensitivity of the two discontinuous deformation modes to the confining pressure. The incipient growth of a geological fold in such a material is modelled as a problem of plate bending. The slip- and opening-modes of deformation are found to be activated typically in the fold intrados and extrados, respectively. Under certain conditions, both modes will be activated simultaneously at the same locality and contribute to the total deformation. Field observations on a well exposed sandstone anticline are reported here, which support this conclusion. The present plasticity model for discontinua can clearly be explored in more detail for realistic distributions of faults and joints taken from field observations. It could also be improved in various ways in its description of the underlying deformation mechanisms. Apart from its interest as a mechanical constitutive model, it can also serve as a point of departure for studies of stress-sensitive, anisotropic permeability distributions in fractured formations. (10.1007/978-3-642-59617-9_5)
  DOI : 10.1007/978-3-642-59617-9_5
• Approche multi-échelle en fatigue polycyclique anisotherme
  
  • Maitournam Habibou
  • Nguyen-Tajan Thi Mac-Lan
  Comptes rendus de l’Académie des sciences. Série IIb, Mécanique, Elsevier, 2000, 328 (5), pp.373-379. Une extension de l'approche macro-méso développée par Dang Van en fatigue isotherme à grand nombre de cycles est proposée dans le cas de structures subissant des chargements cycliques anisothermes et dont les limites de fatigue dépendent de la température. Elle est essentiellement fondée sur l'hypothèse d'adaptation aux échelles macroscopique et mésoscopique. L'utilisation d'une condition locale d'adaptation écrite dans le cas anisotherme conduit à une nouvelle formulation des critères de fatigue. (10.1016/S1620-7742(00)00049-0)
  DOI : 10.1016/S1620-7742(00)00049-0
• The dynamics of discrete mechanical systems with perfect unilateral constraints
  
  • Ballard Patrick
  Archive for Rational Mechanics and Analysis, Springer Verlag, 2000, 154 (3), pp.199-274. The dynamics of discrete mechanical systems with perfect unilateral constraints is formulated in a very general setting. The well-posedness of the resulting evolution problem is studied. It is proved that existence and uniqueness of a maximal solution is ensured provided strong assumptions are made on the regularity of the data: they are supposed to be analytic. Simple examples show that this regularity assumption may not be relaxed. Sufficient conditions to ensure that the maximal solution is defined for all time are supplied. The continuous dependence of the solution on initial conditions is also studied and the numerical computation of the solution is discussed. (10.1007/s002050000105)
  DOI : 10.1007/s002050000105
• On discontinuous stresses at the interface of a bimaterial thermo-elasto-plastic body
  
  • Bui Huy Duong
  • Taheri Said
  • Dang Van Ky
  Advances in Natural Sciences, 2000, 1, pp.79-84.
• Plan/plan sliding contact modelling by the boundary element method
  
  • Serre Ingrid
  • Bonnet Marc
  • Pradeilles-Duval Rachel Marie
  , 2000.
• Hétérogénéité des contraintes au sein d'un matériau lamellaire. Application à un alliage intermétallique TiAl
  
  • Gélébart Lionel
  • Crépin Jérôme
  • Bretheau Thierry
  • Bornert Michel
  , 2000.
• An affine formulation for the prediction of the effective properties of nonlinear composites and polycrystals
  
  • Masson Renaud
  • Bornert Michel
  • Suquet Pierre
  • Zaoui André
  , 2000. Variational approaches for nonlinear elasticity show that Hill's incremental formulation for the prediction of the overall behaviour of heterogeneous materials yields estimates which are too stiff and may even violate rigorous bounds. This paper aims at proposing an alternative `affine' formulation, based on a linear thermoelastic comparison medium, which could yield softer estimates. It is first described for nonlinear elasticity and specified by making use of Hashin±Shtrikman estimates for the linear comparison composite; the associated affine self-consistent predictions are satisfactorily compared with incremental and tangent ones for power-law creeping polycrystals. Comparison is then made with the second-order procedure and some limitations of the affine method are pointed out; explicit comparisons between different procedures are performed for isotropic, two-phase materials. Finally, the affine formulation is extended to history-dependent behaviours; application to the self-consistent modelling of the elastoplastic behaviour of polycrystals shows that it others an improved alternative to Hill's incremental formulation. (10.1016/S0022-5096(99)00071-X)
  DOI : 10.1016/S0022-5096(99)00071-X
• Dynamic testing at high rates of strain
  
  • Gary G.
  , 2000.
• An energetic approach in thermomechanical fatigue for silicium molybden cast iron
  
  • Charkaluk E.
  • Constantinescu Andreï
  Materials at High Temperatures, Taylor and Francis, 2000, 17 (3), pp.373-380. The purpose of this paper is to define a low cycle fatigue criterion in order to predict the failure of engineering structures. The major problem in defining a predictive fatigue criterion is that it should be applicable for structures submitted to complex multiaxial thermo-mechanical loadings but should be identifiable from simple experiments on specimens. After a short critical review of the principal criteria used in low cycle fatigue it will be shown that the dissipated energy per cycle permits a correlation of isothermal and anisothermal results obtained on silicon molybdenum cast iron in the case of specimens and also on structures. (10.1179/mht.2000.17.3.001)
  DOI : 10.1179/mht.2000.17.3.001
• La programmation logique inductive à la lumière de la transition de phase
  
  • Giordana Attilio
  • Saitta Lorenza
  • Sebag Michèle
  • Botta Marco
  , 2000, pp.157-172. En logique du premier ordre, le test de couverture correspond à un problème de satisfaction de contraintes. Or, dans le domaine de la satisfaction de contraintes, les problèmes les plus difficiles à résoudre en moyenne se concentrent dans une étroite région, appelée transition de phase, qui marque la transition entre les problèmes presque surement satisfiables, et les problèmes presque surement insatisfiables. Pour étudier la complexité et la faisabilité de la Programmation Logique Inductive (PLI), nous avons généré quelques centaines de problèmes d’apprentissage, situés dans et hors de la transition de phase; ces problèmes ont été soumis à FOIL, SMART+ et G-Net. Ces expérimentations systématiques établissent deux résultats. Tout d’abord, la transition de phase constitue un attracteur pour l’apprentissage, dans le sens où toutes les hypothèses produites appartiennent à cette région. En second lieu, une "zone aveugle de l’apprentissage" apparaît: pour tout problème situé dans cette zone, les systèmes de PLI considérés échouent tous à apprendre quelque hypothèse pertinente que ce soit. Ces résultats sont interprétés, et la discussion conduit à remettre en cause les biais usuels de la PLI.
• Self-consistent estimates for nonlinear viscoelastic polycrystals: a simplified resolution of the affine formulation adapted to monotonic loading paths
  
  • Brenner Rénald
  • Castelnau Olivier
  • Masson Renaud
  • Bacroix Brigitte
  • Zaoui André
  , 2000, 177-180, pp.153-158. A simplified resolution of the self-consistent model for non-linear viscoelastic polycrystals is presented. The formulation is based on an affine linearization of the constitutive relations as recently proposed by Masson and Zaoui [4], which adapts Hill's conception of self-consistent modelling to nonlinear viscoelastic behaviours. The approximation of the inverse Laplace-Carson transform introduced here, which is believed to be well adapted to monotonic loading paths, makes the resolution of the whole self-consistent problem possible in the direct time space. This results in a largely simplified numerical algorithm. Comparisons with the predictions of a model treating accurately the inverse Laplace-Carson transform are presented, and very good results are obtained for creep of FCC and HCP polycrystals. (10.4028/www.scientific.net/KEM.177-180.153)
  DOI : 10.4028/www.scientific.net/KEM.177-180.153
• Tribological and corrosion behaviours of graphite and titanium alloys couple during ring-on-disk tests
  
  • Serre I.
  • Celati N.
  • Pradeilles Duval R. M.
  , 2000, pp.591-596. No abstract provided
• A regularized BIE formulation for thermo-hydro-mechanical analysis of fractured rocks
  
  • Vahida B.
  • Bonnet Marc
  • Pouya A.
  , 2000. No abstract provided
• Instabilité du glissement stationnaire : application au crissement des freins
  
  • Moirot F.
  • Nguyen Q. S.
  , 2000. No abstract provided
• Damage mechanism of Ti6AL4V substrats coated by tungsten based PVD layers under single particles impact loading
  
  • Graff G.
  • Stolz C.
  • Pradeilles-Duval R. M.
  • Sainte Catherine M.C.
  • Jomeaux S.
  • Penquer F.
  , 2000. No abstract provided
• On global behaviour of heterogeneous media with mechanical transformation along moving surfaces
  
  • Pradeilles-Duval R. M.
  • Stolz C.
  , 2000. No abstract provided
• Thermodynamical description of running discontinuities: application to wear
  
  • Stolz Claude
  , 2000.