Étude d'un modèle de fragmentation secondaire pour les brouillards de gouttelettes

In this Note, we first present a model for droplet secondary breakup, in liquid sprays. This model is based on the kinetic theory formalism and uses experimental correlations found in the literature (L.-P. Hsiang, G.M. Faeth, Int. J. Multiphase Flow 19 (5) (1993) 721–735; R. Maxey, J. Riley, Phys. Fluids 26 (4) (1983) 883–889; M. Pilch, C.A. Erdman, Int. J. Multiphase Flow 13 (6) (1987) 741–757) to determine the fragmentation rate and its outcome. We then conduct a mathematical study of the resulting kinetic equation. We prove, under some physically reasonable assumptions, an existence and uniqueness theorem and characterize the long-time behaviour of the solution. To cite this article: G. Dufour et al., C. R. Acad. Sci. Paris, Ser. I 336 (2003).     

Formulation of a Hysteretic Restoring Force Model. Application to Vibration Isolation

This article focuses on the formulation of a hysteretic model used as anisolator restoring force model. The proposed model is based on operatorgoverning input and output functions that depend on the deflection andthe restoring force of the isolator. First, the mathematical formulationis demonstrated, then the hysteretic model proposed is applied toisolators having different types of behavior. The model parameters aresought using the experimental force-deflection loop of each of theisolators studied. Next, the transient response of a flexible structuremounted on an all-metal isolator is predicted by coupling the firstorder differential equation of the restoring force and the second orderdifferential equations of the structure's motion. The experimentalinvestigation validates the proposed hysteretic model applied to theall-metal mount.     

Chiral resolution by crystallization of host-guest supramolecular complexes

The crystallization behaviour and the physical characterization of supramolecular complexes formed between permethylated-α-cyclodextrin (TMα-CD) and the enantiomers of phenylethanol (PE) are investigated. According to crystal structure analyses, complexes containing the pure guest enantiomers are almost isomorphous, indicating that the host presents a poor ability to distinguish PE enantiomers at a molecular level. Nevertheless, crystallizations from racemic PE in water induce an efficient chiral discrimination and allow the enantio-separation of the guests despite the existence of a solid solution revealed by XRPD and coupled TG-DSC analyses. The enantiodifferentiation is explained by solubility differences between the two diastereomeric complexes in the studied temperature range. Moreover, it is shown that the diastereomeric complex TMα-CD/(S)-PE crystallizes in two distinct phases: a monohydrate and an anhydrous form, with a transition temperature close to 37°C. The insertion of a water molecule in the crystals grown below 37°C does not involve any other change of the crystal packing nor of the molecular conformation, but leads to different crystal growth mechanisms inducing different morphologies and distinct thermal behaviours. This revised version was published online in July 2006 with corrections to the Cover Date.     

Possibility of plasma density diagnostics using Langmuir-wave-caused dips observed in dense laser plasmas

A systematic study of the Langmuir-wave-caused dips (L dips) observed in profiles of the Al Ly γ line emitted from laser irradiated sandwich targets indicates that these fine spectral features can be used as a tool for density diagnostics in intermediately coupled plasmas. The spectroscopic data required for a reliable identification of L dips were collected by a vertical-geometry Johann spectrometer providing high spectral and spatial resolution. The electron densities deduced from the evolution of the L dips along the laser target axis compare well with those derived from hydrosimulations and from measurements of the line widths and shifts.     

Buchbesprechungen

Ohne Zusammenfassung

---

Book reviews

---

Notices bibliographiques

     

Measurements of evaporation residues and fission for 40Ar + 110Pd

Fusion cross sections for the reaction ⁴⁰Ar + ¹¹⁰Pd have been measured in the bombarding energy range 164–262 MeV. Evaporation residues and fission fragments have been detected by ΔE-E telescopes. We compare the fusion cross sections to various theoretical models with special attention to the high-energy data. An analysis is also given for entrance-channel spin zones for evaporation residues and fission.     

Simultaneous production of K1o (892) and Δ++(1236) in the reaction K+p→K+π+π−p from 4.3 to 5.0 GeV/c

The reaction $\text{K}{}^{\mathrm{+}}\text{d}\text{→}\text{K}{}^{\mathrm{1o}}\text{(892) Δ}{}^{\mathrm{++}}\text{(1236)}\text{n}{}_{\mathrm{s}}$ from a K⁺d experiment with the CERN 2 m bubble chamber at 4.6 GeV/c is compared with the reaction $\text{K}{}^{\mathrm{+}}\text{p}\text{→}\text{K}{}^{\mathrm{1o}}\text{(892)Δ}{}^{\mathrm{++}}\text{(1236)}$ from a K⁺p experiment at the same energy. In addition, predictions of an absorption model, a Regge pole model and a quark model for the production and decay characteristics of the reaction $\text{K}{}^{\mathrm{+}}\text{p}\text{→}\text{K}{}^{\mathrm{1o}}\text{(892)Δ}{}^{\mathrm{++}}\text{(1236)}$ are tested with the combined statistics of the K⁺d experiment and three K⁺p experiments between 4.3 and 5.0 GeV/c.     

Comments on “isothermal sustained oscillations in a very simple surface reaction” by C.G. Takoudis,L.D. Schmidt and R. Aris

The oscillating CO oxidation on Pt is examined as a possible candidate for the Takoudis, Schmidt and Aris (TSA) model. Moreover the results of our Monte Carlo simulation of this model reaction are tentatively compared to TSA numerical results.