Results: The group of Bp stars is significantly younger than the group of SPB stars. Longitudinal magnetic fields in SPB stars are weaker than those of Bp stars, suggesting that the magnetic field strength is an important factor for B type stars to become chemically peculiar. The strongest magnetic fields appear in young Bp stars, indicating a magnetic field decay in stars at advanced ages. Rotation periods of Bp and pulsation periods of SPB stars are of the same order and the behaviour of Geneva photometric variability of some Bp stars cannot be distinguished from the variability of SPB stars, illustrating the difficulty to interpret the observed variability of the order of days for B-type stars. We consider the possibility that pulsation could be responsible for the variability among chemically peculiar stars. In particular, we show that a non-linear pulsation model is not excluded by photometry for the Bp star HD 175362. [less ▲]Detailed reference viewed: 4 (0 ULg) On the coherent drag-reducing and turbulence-enhancing behaviour of polymers in wall flowsDubief, Yves; White, Christopher M.; Terrapon, Vincent et alin Journal of Fluid Mechanics (2004), 514Numerical simulations of turbulent polymer solutions using the FENE-P model are used to characterize the action of polymers on turbulence in drag-reduced flows. The energetics of turbulence is ... [more ▼]Numerical simulations of turbulent polymer solutions using the FENE-P model are used to characterize the action of polymers on turbulence in drag-reduced flows. The energetics of turbulence is investigated by correlating the work done by polymers on the flow with turbulent structures. Polymers are found to store and to release energy to the flow in a well-organized manner. The storage of energy occurs around near-wall vortices as has been anticipated for a long time. Quite unexpectedly, coherent release of energy is observed in the very near-wall region. Large fluctuations of polymer work are shown to re-energize decaying streamwise velocity fluctuations in highspeed streaks just above the viscous sublayer. These distinct behaviours are used to propose an autonomous regeneration cycle of polymer wall turbulence, in the spirit of Jimenez & Pinelli (1999). [less ▲]Detailed reference viewed: 54 (5 ULg) On the collapse behaviour of oil reservoir chalkDe Gennaro, Vincenzo; Delage, Pierre; Priol, Grégoire et alin Geotechnique (2004), 54(6), 415-420Oil exploitation in North Sea Ekofisk oilfield started in 1971, the reservoir is located in a 150 m thick layer of porous chalk (n = 40-50%) at a 3000 m depth. Enhanced oil recovery procedure by sea water ... [more ▼]Oil exploitation in North Sea Ekofisk oilfield started in 1971, the reservoir is located in a 150 m thick layer of porous chalk (n = 40-50%) at a 3000 m depth. Enhanced oil recovery procedure by sea water injection (waterflooding) was initiated in 1987. Starting from this date, seabed subsidence due to chalk compaction evolves at a fairly constant rate (i.e. 40 cm/year). Nowadays, the decrease of the seafloor level is of about 10 m. Reservoir management and production strategies are at the origin of the growing interest of petroleum industry in disposing of a comprehensive description of the chalk mechanical behaviour. In this note the subsidence due to waterflooding is interpreted within a framework taken from the mechanics of unsaturated soils. By considering oil as the non-wetting fluid and water as the wetting fluid, chalk compaction is depicted as a collapse phenomenon due to oil-water suction decrease. A series of suction controlled tests in the osmotic oedometer cell are presented. Water weakening effects and chalk compaction (collapse) seem likely to occur through the lost of strength of the inter-granular links existing in the oil saturated sample. The nature of these links includes both capillary and physico-chemical fluids-chalk interactions, and is well characterised by the oil-water suction. [less ▲]Detailed reference viewed: 133 (5 ULg) On the combination of corpus-based and experimental methodologies in the study of causal, contrastive and metadiscourse connectives in L1 and L2 text comprehension and productionPerrez, Julien ; Degand, Liesbethin Archer, Dawn; Rayson, Paul; Wilson, Andrew (Eds.) et al Proceedings of the Corpus Linguistics 2003 Conference (2003)Detailed reference viewed: 14 (1 ULg) On the complementarity of contrastive linguistics and interlanguage studiesRasier, Laurent ; Hiligsmann, PhilippeConference (2008)Detailed reference viewed: 21 (1 ULg) On the concept of exposure timeDelhez, Eric in Continental Shelf Research (2013), 71The concept of exposure time offers an interesting alternative to the residence time for the quantitative assessment of the water renewal of estuaries and semi-enclosed basins. It can cope with the ... [more ▼]The concept of exposure time offers an interesting alternative to the residence time for the quantitative assessment of the water renewal of estuaries and semi-enclosed basins. It can cope with the oscillations or meandering of the flow around the boundary of the control domain and is therefore particularly suited for tidal seas and sub-basins with strong mesoscale activity. We show however that the exposure time in a control domain \omega cannot be properly defined if \omega is part of a larger bounded system unless some removal process is taken into account. It is therefore suggested to revise and extend the definition of the exposure time by including a first order decay : the exposure time for the rate constant \lambda is the total time spent in a control domain \omega by particles subject to a first order decay with a rate constant $\lambda$, irrespective of their possible excursions in and out the control domain''. The exposure time revised in this way is well-defined in all circumstances provided that the decay rate differs from zero but depends on the rate constant \lambda. Alternatively, in order to diagnose the movement of water masses, the first order decay can be considered only outside the control domain. [less ▲]Detailed reference viewed: 18 (4 ULg) On the concrete complexity of the successor functionBerthé, Valérie; Frougny, Christiane; Rigo, Michel et alConference (2012, September 11)We consider two kinds of questions about the successor function. The ﬁrst one is concerned with the estimation of the length of the carry propagation when applying the successor map on the first n ... [more ▼]We consider two kinds of questions about the successor function. The ﬁrst one is concerned with the estimation of the length of the carry propagation when applying the successor map on the first n integers (or more generally on the first n elements in a given language). This leads to the notion of amortized (or average) carry propagation when applying the successor function. The second question is a computational issue: estimating the number of operations (in classical terms of Turing machines complexity) required to compute the representations of the first n integers from the first one by applying n times the successor function. This leads to the notion of (amortized) complexity, i.e., the average amount of computations required to obtain the successor of an element. [less ▲]Detailed reference viewed: 60 (4 ULg) On the constitutive equations of the chalkCharlier, Robert ; Radu, Jean-Pol in ICONMIG'88 (1988)Detailed reference viewed: 13 (4 ULg)