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81.
We investigate the steady-state rheological behaviour of the lamellar phase of a lyotropic system (CpCl, hexanol, brine)
and of a thermotropic system (8CB). Power laws characterize the behaviour of the imposed stress as a function of the measured
shear rate and similarities are observed for both systems; the same regime γ˙∼σ
m
with m≈1.7 is obtained at low shear stresses corresponding to a texture of oily streaks oriented in the direction of the flow, as
shown by microscopic observations. The “onion state” only exists in the case of dilute samples of the lyotropic lamellar phase;
the stress then varies as γ˙∼σ
m
with m≈4.8, as already observed by other groups with different systems. Rheological measurements at different temperatures allow
determination of different activation energies relating to the still badly understood processes involved in the different
rheological regimes. We propose a model which reproduces the experimental power laws and which is based on an analogy with
the theory of high-temperature creep in metals and alloys.
Received: 19 October 1999/Accepted: 1 November 1999 相似文献
82.
Claude Laflamme Maurice Pouzet Norbert Sauer 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》2017,87(2):369-408
A tree is scattered if it does not contain a subdivision of the complete binary tree as a subtree. We show that every scattered tree contains a vertex, an edge, or a set of at most two ends preserved by every embedding of T. This extends results of Halin, Polat and Sabidussi. Calling two trees equimorphic if each embeds in the other, we then prove that either every tree that is equimorphic to a scattered tree T is isomorphic to T, or there are infinitely many pairwise non-isomorphic trees which are equimorphic to T. This proves the tree alternative conjecture of Bonato and Tardif for scattered trees, and a conjecture of Tyomkyn for locally finite scattered trees. 相似文献
83.
Mathematical Programming - Switching machines on and off is an important aspect of unit commitment problems and production planning problems, among others. Here we study tight mixed integer... 相似文献
84.
85.
Horst W. Hamacher Jean-Claude Picard Maurice Queyranne 《Operations Research Letters》1984,2(6):303-305
We show that the O(K · n4) algorithm of Hamacher (1982) for finding the K best cut-sets fails because it may produce cuts rather than cut-sets. With the convention that two cuts and are different whenever X ≠ Y the K best cut problem can be solved in O(K · n4). 相似文献
86.
Endre?Bj?rndal Maurice?KosterEmail author Stef?Tijs 《Mathematical Methods of Operations Research》2004,59(2):249-270
In this paper we consider standard fixed tree games, for which each vertex unequal to the root is inhabited by exactly one player. We present two weighted allocation rules, the weighted down-home allocation and the weighted neighbour-home allocation, both inspired by the painting story in Maschler et al. (1995) . We show, in a constructive way, that the core equals both the set of weighted down-home allocations and the set of weighted neighbour allocations. Since every weighted down-home allocation specifies a weighted Shapley value (Kalai and Samet (1988)) in a natural way, and vice versa, our results provide an alternative proof of the fact that the core of a standard fixed tree game equals the set of weighted Shapley values. The class of weighted neighbour allocations is a generalization of the nucleolus, in the sense that the latter is in this class as the special member where players have all equal weights. 相似文献
87.
Structure of a simple scheduling polyhedron 总被引:5,自引:0,他引:5
Maurice Queyranne 《Mathematical Programming》1993,58(1-3):263-285
88.
The initial state of liquid atomization by a fast gas stream is considered by viscous linear spatial stability analysis for parallel two-fluid flow. The unbounded basic velocity profile is characterized by different asymptotic velocities and a velocity deficit near the interface. We examine the influence of the velocity deficit on the spatial growth rates of two competing modes originating from the Kelvin-Helmholtz and viscosity contrast mechanisms. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
89.
Fran?ois B Vialatte Jordi Solé-Casals Justin Dauwels Monique Maurice Andrzej Cichocki 《BMC neuroscience》2009,10(1):46
Background
oscillatory activity, which can be separated in background and oscillatory burst pattern activities, is supposed to be representative of local synchronies of neural assemblies. Oscillatory burst events should consequently play a specific functional role, distinct from background EEG activity – especially for cognitive tasks (e.g. working memory tasks), binding mechanisms and perceptual dynamics (e.g. visual binding), or in clinical contexts (e.g. effects of brain disorders). However extracting oscillatory events in single trials, with a reliable and consistent method, is not a simple task. 相似文献90.
Vincent Maurice 《Surface science》2005,581(1):88-104
STM, STS, LEED and XPS data for crystalline θ-Al2O3 and non-crystalline Al2O3 ultra-thin films grown on NiAl(0 0 1) at 1025 K and exposed to water vapour at low pressure (1 × 10−7-1 × 10−5 mbar) and room temperature are reported. Water dissociation is observed at low pressure. This reactivity is assigned to the presence of a high density of coordinatively unsaturated cationic sites at the surface of the oxide film. The hydroxyl/hydroxide groups cannot be directly identify by their XPS binding energy, which is interpreted as resulting from the high BE positions of the oxide anions (O1s signal at 532.5-532.8 eV). However the XPS intensities give evidence of an uptake of oxygen accompanied by an increase of the surface coverage by Al3+ cations, and a decrease of the concentration in metallic Al at the alloy interface. A value of ∼2 for the oxygen to aluminium ions surface concentration ratio indicates the formation of an oxy-hydroxide (AlOxOHy with x + y ∼ 2) hydroxylation product. STM and LEED show the amorphisation and roughening of the oxide film. At P(H2O) = 1 × 10−7 mbar, only the surface of the oxide film is modified, with formation of nodules of ∼2 nm lateral size covering homogeneously the surface. STS shows that essentially the valence band is modified with an increase of the density of states at the band edge. With increasing pressure, hydroxylation is amplified, leading to an increased coverage of the alloy by oxy-hydroxide products and to the formation of larger nodules (∼7 nm) of amorphous oxy-hydroxide. Roughening and loss of the nanostructure indicate a propagation of the reaction that modifies the bulk structure of the oxide film. Amorphisation can be reverted to crystallization by annealing under UHV at 1025 K when the surface of the oxide film has been modified, but not when the bulk structure has been modified. 相似文献