Showing papers by "École Polytechnique published in 1982"
TL;DR: In this article, a chain of one-dimensional oscillators is considered and the total energy is kept constant except for the interactions of the extremal oscillators with reservoirs at different temperatures.
Abstract: A chain of one-dimensional oscillators is considered. They are mechanically uncoupled and interact via a stochastic process which redistributes the energy between nearest neighbors. The total energy is kept constant except for the interactions of the extremal oscillators with reservoirs at different temperatures. The stationary measures are obtained when the chain is finite; the thermodynamic limit is then considered, approach to the Gibbs distribution is proven, and a linear temperature profile is obtained.
275 citations
01 Jan 1982
TL;DR: In this article, a reduced equidimensional analytic algebra OX,x is associated with a sequence of d integers, where mx denotes the multiplicity at x, and pk (X) is a general local polar variety of codimension k of X, as defined by Le D.T. and myself.
Abstract: To each reduced equidimensional analytic algebra OX,x, one can associate a sequence of d integers, where OX,x:
$$M_{X,x}^* = \{ m_x (X),m_x (P_1 (X)),...,m_x (P_{d - 1} (X))\}$$
where for 0≤k≤d−1, Pk (X) is a general local polar variety of codimension k of X, as defined by Le D.T. and myself, and mx denotes the multiplicity at x.
223 citations
TL;DR: In this article, a generalization of the Painlev\'e conjecture for two-dimensional Hamiltonian systems is presented, which is compatible with all the systems already found and leads to still new integrable cases.
Abstract: The discovery of new integrable two-dimensional Hamiltonian systems is reported. The analytic structure of the solutions makes necessary the generalization of the Painlev\'e conjecture, a widely used integrability criterion. Such a generalization is presented, which the authors believe should replace the usual conjecture for two-dimensional Hamiltonian systems. It is indeed compatible with all the systems already found and, in addition, leads to still new integrable cases.
201 citations
TL;DR: A characterization of all minimum cuts, separating a source from a sink in a network, and applications arise in sensitivity and parametric analyses of networks, the vertex packing and maximum closure problems, in unconstrained pseudo-boolean optimization and project selection, as well as in other areas of application of minimum cuts.
Abstract: This paper presents a characterization of all minimum cuts, separating a source from a sink in a network. A binary relation is associated with any maximum flow in this network, and minimum cuts are identified with closures for this relation. As a consequence, finding all minimum cuts reduces to a straightforward enumeration. Applications of this results arise in sensitivity and parametric analyses of networks, the vertex packing and maximum closure problems, in unconstrained pseudo-boolean optimization and project selection, as well as in other areas of application of minimum cuts.
192 citations
TL;DR: In a committee where cooperative voting occurs, effectivity functions describe the blocking power of coalitions as mentioned in this paper, a binary relation that says for each coalition T and each subset of outcomes B whether or not T can force the final outcome within B. The corresponding cooperative stability notion generalizes the familiar core of a simple game.
185 citations
TL;DR: In this paper, the quasiconvexity of relaxation relaxation is investigated in the context of quasiscience, and the authors propose a relaxation approach based on quasico-vetoity.
165 citations
157 citations
TL;DR: In this paper, the total dissociation cross sections for silane and disilane are reported for electron energies above their ionization thresholds up to 110 eV. The measurements are derived from a kinetic analysis of silane/disilane dissociation in a constant flow multipole dc plasma reactor.
145 citations
TL;DR: In this article, the effect of RuO2 is attributed to catalysis of hole transfer from the valence band of CdS to H2S or sulfide ion in solution.
Abstract: Illumination of US-dispersions by visible light in solutions containing H2S or sulfide ions leads to efficient generation of hydrogen and sulfur. Very small quantities of RuO2 deposited on the CdS-particles improve markedly the quantum yield of H2-formation for which the optimum value obtained so far is ϕ = 0.35 ± 0.1. The effect of RuO2 is attributed to catalysis of hole transfer from the valence band of CdS to H2S or sulfide in solution.
130 citations
TL;DR: In this paper, the reversed phase chromatographic behavior of a homologous series has been investigated as a function of the mobile phase composition and temperature, and it was found that the methylene selectivity decreased with increasing temperature and decreasing amount of water.
109 citations
TL;DR: A network flow technique is used to solve the unconstrained nonlinear 0-1 programming problem, which is maximizing the ratio of two polynomials, assuming that all the nonlinear coefficients in the numerator are non-negative and all theNonlinear coefficientsIn the denominator arenonpositive.
Abstract: A network flow technique is used to solve the unconstrained nonlinear 0-1 programming problem, which is maximizing the ratio of two polynomials, assuming that all the nonlinear coefficients in the numerator are non-negative and all the nonlinear coefficients in the denominator are nonpositive. Two examples are an investment selection problem to maximize the rate of return, and a decomposition approach to a scheduling problem studied by Sidney and Lawler. The proposed algorithm requires the solution of a sequence of minimum-cut problems in a related network, and can be extended to some more general problems of the same type. This approach is also applied to find the density of a graph (the maximum ratio, among its subgraphs, of the number of edges to the number of nodes) and its arboricity, for which polynomial algorithms are described. It is also useful in providing a bounding scheme for the maximum-clique and vertex packing problems.
TL;DR: Domains, called sets of single-peaked linear orders on a tree, are provided, which enjoy such a property and appear as a generalization of the well-known sets ofsingle-peaking linear orders.
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TL;DR: In this paper, a generalization of single-peaked linear orders on a tree is proposed, which guarantee the existence of a majority winner without necessarily ensuring the transitivity of the strict majority rule.
Abstract: Inada (1969) and Sen and Pattanaik (1969) have characterized the sets of preference orders which ensure the transitivity of the strict majority rule, no matter how each voter selects his own order in the set. But a problem remains untouched: which domains of orders guarantee the existence of a majority winner without necessarily ensuring the transitivity of the strict majority rule. We provide in this paper domains, called sets of single-peaked linear orders on a tree, which enjoy such a property. They appear as a generalization of the well-known sets of single-peaked linear orders.
TL;DR: In this paper, the authors measured mass-ablation rate as a function of absorbed laser flux and laser wavelength, and showed that heat-flux inhibition occurs at each wavelength, but the mechanisms are very different.
Abstract: Thin-foil experiments at 1.06, 0.53, and 0.26 \ensuremath{\mu}m have been realized in order to measure mass-ablation rate $\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{m}$ as a function of absorbed laser flux ${\ensuremath{\varphi}}_{a}$ and laser wavelength $\ensuremath{\lambda}$. The results can be put in the form $\stackrel{\ifmmode \dot{}\else \.{}\fi{}}{m}(\mathrm{kg}/\mathrm{s}{\mathrm{cm}}^{2})\ensuremath{\approx}110{[{\ensuremath{\varphi}}_{a}\frac{(\mathrm{W}/{\mathrm{cm}}^{2})}{{10}^{14}}]}^{\frac{1}{3}}{\ensuremath{\lambda}}_{\ensuremath{\mu}\mathrm{m}}^{\ensuremath{-}\frac{4}{3}}$. Hydrodynamical simulations of these experiments show that heat-flux inhibition occurs at each wavelength, but the mechanisms are very different.
TL;DR: Aqueous sols of TiO2 (anatase, particle radius 25 A) were excited with (347.1 nm)-laser light and the reaction of valence-band holes with halide ions (X = I−, Br−, Cl−) was investigated as discussed by the authors.
Abstract: Aqueous sols of TiO2 (anatase, particle radius 25 A) were excited with (347.1 nm)-laser light and the reaction of valence-band holes with halide ions (X = I−, Br−, Cl−) was investigated. Hole transfer takes place within the duration of the (10 ns)-laser pulse and results in the formation of anion radicals according to the sequence:
The quantum yield of X increases in the order Cl < Br < I, attaining 0.8 for I at pH 1. It is affected by pH, halide concentration and the presence of a protective agent for the sol.
RuO2 deposited onto TiO2 enhances markedly Cl and Br -formation, but has no effect on the yield of I.
Laser-photolysis investigation of halide oxidation were also carried out with colloidal Fe2O3 (particle radius 600 A). For I2−formation, the quantum yield exceeds 0.9 indicating almost quantitative hole scavenging by iodide.
TL;DR: Optical emission spectroscopy in the visible and near UV of a silane plasma was performed in a low pressure hot cathode glow discharge bounded into a magnetized multipolar wall as mentioned in this paper.
TL;DR: In this paper, an analytical theory of a transverse-pumped dye amplifier was developed and the steady-state distribution of the excited state population and the total stored energy was solved for a given distribution of excited state molecules.
Abstract: Laser-pumped dye amplifiers are the most convenient way to amplify ultrashort light pulses. In this paper, we develop an analytical theory of a transverse-pumped dye amplifier and compute the steady-state distribution of the excited state population and the total stored energy. The equation for the traveling amplified pulse is then solved for a given distribution of excited state molecules. The efficiency of an amplification stage associated with the distortion of the temporal pulse shape is obtained as a function of the input and stored energy density, normalized to the saturation level. The theoretical results are then compared to measurements obtained from an experimental arrangement of a three-stage optically pumped dye laser amplifier, which amplifies subpicosecond pulses from a passively mode-locked CW dye laser, to produce pulses with a peak intensity of 3 GW while maintaining a 0.5 picosecond pulsewidth.
TL;DR: In this paper, a bispectral technique was employed to determine the cirrus cloud-top temperature using data collected from aircraft equipped with the ARIES radiometer, which on sixteen flights provided IR readings at 6.5 and 11.5 microns of cirrus tops.
Abstract: A bispectral technique was employed to determine the cirrus cloud-top temperature. Data were gathered from aircraft equipped with the ARIES radiometer, which on sixteen flights provided IR readings at 6.5 and 11.5 microns of cirrus tops. The flights were made on a NASA Convair to a maximum ceiling of 12,500 m. The brightness temperatures above the cirrus were found to be consistently colder, by up to 40 K, than the 11.5 microns window channel, and good spatial correlations were displayed over whole clouds. Effective emissivities are calculated for both channels and applied to Meteosat digital imagery. The subsequent derived temperatures were significantly colder than black-body temperatures, which is explained by taking into account the absorption of emitted radiation by water vapor.
TL;DR: From a selection of Voyager IRIS spectra corresponding to cloud-free areas of Jupiter, this paper determined the CH/sub 4/H/sub 2/ volume ratio in the atmosphere of this planet as equal to (1.95 +- 0.22)10/sup -3/ which corresponds to 2.07 + 0.24 times the solar value of Lambert (C/H = 4.7 x 10/sup −4/).
Abstract: From a selection of Voyager IRIS spectra corresponding to cloud-free areas of Jupiter, we have determined the CH/sub 4//H/sub 2/ volume ratio in the atmosphere of this planet as equal to (1.95 +- 0.22)10/sup -3/ which corresponds to 2.07 +- 0.24 times the solar value of Lambert (C/H = 4.7 x 10/sup -4/). Estimate of errors includes both instrument noise and systematic uncertainties. Implications of this result on the formation and evolution of Jupiter are discussed.
TL;DR: In this paper, a finite element approximation for the stationary Stokes and Navier Stokes equations in a bounded domain in?3 is introduced, which can be used tetahedrons or cubes.
Abstract: We introduce some new families of finite element approximation for the stationary Stokes and Navier Stokes equations in a bounded domain in ?3. These elements can used tetahedrons or cubes. The approximation satisfie exactly the incompressibility condition.
TL;DR: In the Kobayashi-Maskawa model, the GIM cancellation comes in the Penguin case from (α s π ) log m 2 t m 2 c abd not from π −2 (m 2 t −m 2 c ) M 2 W as for the transition quark electric dipole moment.
01 Jan 1982
TL;DR: In this article, Mumford pointed out that la cubique n'est pas rationnelle (un partie des r~sultats de [C-G] avait 6t6 obtenue independenue indienue independence par Tjurin IT2]).
Abstract: Introduction La g6om~trie de l'hypersurface cubique de dimension 3 a ~t6 61ucid6e par Clemens et Griffiths ~C-G] ~ citons, parmi les r~sultats les plus frappants, le th~oreme de Torelli et le fait que la cubique n'est pas rationnelle (une partie des r~sultats de [C-G] avait 6t6 obtenue ind6pendamment par Tjurin IT2]). Clemens et Griffiths utilisaient des arguments d61icats de d~g~n~reseence ~ Mumford a observ~ qu'on peut d6duire l'irrationalit~ de la cubique de la th~orie des vari~t~s de Prym.
TL;DR: In this paper, the authors present evidence for the production of two J/ψ mesons in the same interaction (13 events seen, for an expected background of about 0.2 events).
TL;DR: In this paper, it was shown that when correlations in an equilibrium classical system in $\ensuremath{
u}$ dimensions, containing charges decay faster than the distance of the particles, then the charge cloud surrounding particles has no multipole moments of order $kl~l$.
Abstract: It is proven that when correlations in an equilibrium classical system in $\ensuremath{
u}$ dimensions, $\ensuremath{
u}g~2$, containing charges decay faster than ${(\mathrm{distance})}^{\ensuremath{-}(l+\ensuremath{
u})}$ then the charge cloud surrounding particles has no multipole moments of order $kl~l$. This yields $l+1$ sum rules with $l=\ensuremath{\infty}$ when the decay is exponential. This extends previous results for $ll~2$ sum rules and also generalizes them to systems containing fixed dipoles (or higher multipoles). Some consequences are described.
TL;DR: In this article, the influence of cultural, social, and architectural factors on the meaning and use of domestic spaces is studied, and an understanding of the history of the kinds of ideas which are invested in the spatial form and the use of houses is presented.
Abstract: This essay presents a study of the influence of certain cultural, social, and architectural factors upon the meaning and use of domestic space. It attempts to promote an understanding of the history of the kinds of ideas which are invested in the spatial form and use of houses. In addition, it establishes the principle that the meaning and use of domestic space are not intrinsic to a set of physical characteristics, nor the nomenclature applied to rooms and their facilities.
TL;DR: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented in this paper, which relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N.
Abstract: An experimental simulation of a single-channel, double-angle viewing technique for the determination of sea surface temperature from satellite is presented. This method relies upon the fact that the same area can be viewed simultaneously at two different angles (different air masses) by the geostationary satellite METEOSAT and by the polar orbiting satellite TIROS-N. Extrapolating the two air mass observations to zero air mass is shown to give a value of the temperature in good agreement with the true sea surface temperature. A discussion concerning the viewing angles is presented.
TL;DR: In this article, a modification which reduces the computational cost of particle-in-cell algorithms for simulation of plasmas is described, which is obtained by integrating only the electrons through a number of time steps (sub-cycles) in order to resolve their evolution, while integrating the much slower ions only once per cycle.
TL;DR: In this article, the occurrence of tetracyclic triterpanes in petroleum was reported, which presumably derive from pentacy-clic hopanes by ring C opening, and one C30H54 8,14-seco-hopane has been effected by means of comparison with a mixture of synthetic isomeric compounds.
TL;DR: In this article, it was shown that contributions from threshold effects in coupling constant differences at low energies in GUTs are simply taken into account in a scheme that preserves supersymmetry (DR dimensional reduction).
TL;DR: Inverse chromatography was applied to evaluate interaction parameters for polyethylene (PE), polyvinyl chloride (PVC), and CaCO3, these parameters being based on retention volumes of proton-donor, -acceptor, and neutral vapors as mentioned in this paper.
Abstract: Inverse chromatography was applied to evaluate interaction parameters for polyethylene (PE), polyvinyl chloride (PVC), and CaCO3, these parameters being based on retention volumes of proton-donor, -acceptor, and neutral vapors. The acid/base characteristics of CaCO3 were controllably altered by exposing the particulate to microwave plasmas sustained by acidic and basic vapors. It was shown that the ease-of-dispersion of fillers in the polymer matrixes related with the acid–base interaction balance in the polymer-filler pair, and varied widely with the surface treatment given to the filler. Mechanical properties at large deformation of the filled polymers and their durability also were shown to depend on surface interactions. Optimization of properties in PVC compounds was favored when strong acid-base interactions could take place with the plasma-modified filler. In the case of PE, properties were superior when unmodified filler was used; imparting strongly acidic or basic surface properties to the filler diminished its “compatibility” and usefulness with this nonpolar matrix.