排序方式: 共有40条查询结果,搜索用时 15 毫秒
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P. Weibel D. Malterre M. Grioni B. Dardel Y. Baer 《Zeitschrift für Physik B Condensed Matter》1992,87(2):165-168
High resolution photoemission and bremsstrahlung isochromat spectroscopy experiments have been carried out on CeAg and LaAg. From a comparison between these two compounds, we extract the cerium 4f spectral function, we compare it with band structure calculations and with many-body model simulations based on the single-impurity Anderson Hamiltonian. We show that the localized 4f charge estimated from previous band structure calculations cannot be identified with the 4f occupation number deduced from the Anderson model. 相似文献
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Eric Dardel 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1987,38(3):366-377
The propagation of perturbations in liquid filled elastic tubes depends on the stream velocity of the basic flow. This phenomenon is currently analyzed with the method of the characteristics which relies upon a basic flow with a rectangular velocity profile. It seems that this one-dimensional flow approximation has not been convincingly validated, which justifies to consider other, more general velocity profiles.In the present analytical study the velocity profile is a quadratic function of the radial coordinate. Small amplitude perturbations are superposed on this inviscid, basic state in which the mean velocity is arbitrarily large. A normal mode analysis shows that the velocity profile and therefore the vorticity of the basic flow influence the more the phenomenon the larger is. For example, a parabolic profile allows countercurrent wave propagation regardless of.This questions the one-dimensional wave propagation theory in compliant tubes and, consequently, the interpretation of several physiological and medical problems mainly in the respiratory and cardio-vascular systems.
Resumé La propagation de perturbations dans un tube élastique conduisant un écoulement fluide dépend de la vitesse de l'écoulement de base. Ce phénomène est habituellement étudié avec la méthode des caractéristiques, où l'on suppose que le profil de vitesse de l'écoulement est rectangulaire. Comme cette simplification ne semble pas avoir été bien validée, il paraît indiqué d'étudier l'impact d'autres profils.Dans la présente étude analytique, ce profil de vitesse est une fonction quadratique de la coordonée radiale. A cet écoulement non visqueux, dont la vitesse moyenne est arbitraire, l'on superpose des perturbations de faible amplitude. Une analyse linéarisée montre que le profil de vitesse et donc le rotationel de l'écoulement de base influencent d'autant plus ce phénomène d'ondes que est élévée.Ceci met en question la théorie uni-dimensionelle de la propagation d'ondes dans des tubes compliants et, par là-même, l'interpretation de divers problèmes physiologiques et médicaux, avant tout des systèmes respiratoires et cardio-vasculaires.相似文献
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Nonlinear vibration mitigation of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc 总被引:1,自引:0,他引:1
Nonlinear Dynamics - This study is dedicated to investigate the nonlinear dynamics of a system composed of a flexible rotor shaft carrying a longitudinally dispositioned unbalanced rigid disc. The... 相似文献
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H.W. Atherton C. Bovet P. Coet R. Desalvo N. Doble R. Maleyran E.W. Anderson G. Von Dardel K. Kulka M. Boratav J.W. Cronin B.D. Milliken 《Physics letters. [Part B]》1985,158(1):81-84
The lifetime of the neutral pion (π0) has been directly measured. The lifetime has been found to be τπ0 = (0.897±0.022±0.017) × 10?16 s. The systematic error results from uncertainties in the momentum spectrum of the π0 used for the measurement. This measurement yields a decay width of the π0 of (7.34±0.18±0.11) eV. An axial anomaly calculation, which neglects the finite mass of the π0, predicts a value of 7.87 eV. 相似文献
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Daniel Guillon Jean-François Nierengarten Jean-Louis Gallani Jean-François Eckert Yannick Rio Maria del Pilar Carreon Blaise Dardel Robert Deschenaux 《Macromolecular Symposia》2003,192(1):63-74
Growing attention is currently devoted to large dendritic structures for applications in nanotechnology and materials science. In this respect, the incorporation of such compounds into thin ordered films appears to be an important issue. One of the most widely pursued approaches to structurally ordered dendrimer assemblies has been the preparation of Langmuir films at the air-water interface. We report on the case of a diblock globular fullerene-based dendrimer and show that peripheral substitution of the dendrimer with hydrophobic chains on one hemisphere and hydrophilic groups on the other provides the required hydrophobic/hydrophilic balance allowing the formation of stable Langmuir films. A second approach has been to consider the case of fullerene containing dendrimers terminated by mesogenic groups such as cyanobiphenyl subunits. Whatever the generation is, up to the fourth one, all these compounds exhibit a well-defined liquid crystalline smectic A phase. The molecular organisation within the smectic layers is found to be monolayered or bilayered depending on the generation. For the smallest dendrimers, the organisation is mainly governed by the size of the fullerene moiety, whereas for the higher ones, it is governed by the interactions between the terminal mesogenic groups. These two approaches appear particularly interesting for functional groups such as fullerenes, which are not well adapted to be organised in nanoscale architectures. The present study shows that fullerenes can indeed be introduced into different types of ordered structure when they have been chemically adequately modified. 相似文献
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Mohammad Mehdi Barzegari Morteza Dardel Alireza Fathi 《Acta Mechanica Solida Sinica》2013,26(5):536-550
In this study, analytical relations for evaluating the exact solution of natural fre- quency and mode shape of beams with embedded shape memory alloy (SMA) wires are presented. Beams are modeled according to Euler-Bernoulli, Timoshenko and third order beam (Reddy) the- ories. A relation is obtained for determining the effect of axial load generated by the recovery action of pre-strained SMA wires. By defining some dimensionless quantities~ the effect of different me- chanical properties on the frequencies and mode shapes of the system are carefully examined. The effect of axial load generated by SMA wires with buckling load and frequency jump is accurately studied. 相似文献
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P. Weibel M. Grioni D. Malterre B. Dardel Y. Baer M. J. Besnus 《Zeitschrift für Physik B Condensed Matter》1993,91(3):337-341
Temperature dependent photoelectron spectra of the heavy fermion YbAgCu4 show that the Kondo resonance is strongly depressed with increasing temperature. The observed reduction is fully consistent with the predictions of the Anderson impurity model, and reveals the transition from a Fermi liquid at low temperature to localized moments above the characteristic Kondo temperature. Despite this important experimental confirmation of the model, discrepancies exist between the experimental and calculated linewidth of the resonance. It is argued that a more realistic treatment of the photoemission process would improve the agreement between theory and experiment. 相似文献