A kinematical study of Kirchhoff-Rayleigh flow

Summary A method of calculating the separated flow of a viscous fluid is proposed, which allows to split up properly the boundary condition problem from the viscous phenomena. The theory is developed for the flow past a plate and yields wakes of finite extension having an underpressure which depends directly on the amount of vorticity diffusion and dissipation occurring in the fluid. Application of the method to real flows shows good agreement between the calculated and the measured velocity distributions in front of the plate and in the wake.

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Résumé Une méthode de calcul de l'écoulement décollé d'un fluide visqueux est proposée qui permet de séparer clairement le problème aux limites des phénomènes visqueux. La théorie est développée pour l'écoulement autour d'une plaque et donne des sillages de longueur finie ayant une dépression de culot directement dépendante de l'intensité de la diffusion et dissipation de la vorticité se produisant dans le fluide. L'application de la méthode à des écoulements réels montre une bonne concordance entre les répartitions de vitesse calculées et mesurées sur le devant de la plaque et dans le sillage.

     

Method for synthesis ofα,β-unsaturated sulfides from dithiolacetates

Conclusions A method was developed for the synthesis of di(vinylthio) ethers, which consisted in the alkaline cleavage of dithiolacetates in the presence of acetylene.Translated from Izvestiya Akademii Nauka SSSR, Seriya Khimicheskaya, No. 4, pp, 954–956, April, 1972.     

Gas phase activation energy for unimolecular dissociation of biomolecular ions determined by focused RAdiation for gaseous multiphoton ENergy transfer (FRAGMENT)

We present a novel approach for the determination of activation energy for the unimolecular dissociation of a large (>50 atoms) ion, based on measurement of the unimolecular dissociation rate constant as a function of continuous-wave CO(2) laser intensity. Following a short ( approximately 1 s) induction period, CO(2) laser irradiation produces an essentially blackbody internal energy distribution, whose 'temperature' varies inversely with laser intensity. The only currently available method for measuring such activation energies is blackbody infrared radiative dissociation (BIRD). Compared with BIRD, FRAGMENT: (a) eliminates the need to heat the surrounding ion trap and vacuum chamber to each of several temperatures (each requiring hours for temperature equilibration); (b) offers a three-fold wider range of effective blackbody temperature; and (c) extends the range of applications to include initially cold ions (e.g., gas-phase H/D exchange). Our FRAGMENT-determined activation energy for dissociation of protonated bradykinin, 1.2 +/- 0.1 eV, agrees within experimental error to the value, 1.3 +/- 0.1 eV, previously reported by Williams et al. from BIRD experiments. Copyright 1999 John Wiley & Sons, Ltd.     

Precision measurement of nuclear muon capture by3He

In this article we report the results of an experiment performed in 1993 at PSI. The goal was to determine the absolute rate of nuclear muon capture by³He. In the experiment we used a new technique recently developed at Gatchina. As a preliminary result from this experiment we obtained _c=(1496±3(stat)-3(syst)) s^–1.     

A new project for the investigation of unsolved problems of ddµ and pdµ catalysis in D2 and H/D mixtures

We propose to study a number of open problems in ddµ and pdµ fusion using the new high-pressure ionization chamber for charged particle identification in coincidence with the n-/e-counter array for the detection of neutrons and µ-decay electrons. Our first objective will be a precise measurement of the absolute rates of resonant and non-resonant ddµ formation in D₂ and HD-gases and their temperature dependence from 40 to 350 K. Both output channels of the dd-reaction:³He + n and t + p will be observed and their ratio sensitive to contributions of S and P-waves will be determined. Simultaneously, we shall investigate the pdµ-cycle and determine the absolute pd-fusion yields in different molecular H/D compositions, observing tritons from nuclear muon capture in³Heµ: pdµ ³Heµ + . We have developed a special system for the preparation of HD-gas with high concentration (96%) of HD and a purity (10^–6).     

Experimental survey of the sticking problem in muon catalyzed dt fusion

The sticking process dt + n, which constitutes the most severe limit to the number of fusions which a muon can catalyze, is reviewed. Many attempts were made to determine by calculations and measurements the probability for initial sticking _s ⁰ (immediately after dt fusion) and for final sticking _s (after the came to rest). Previous results based on neutron disappearance rates and on the observation of -X-rays were controversial and also in some disagreement with theory. New data are reported from PSI on direct observation of final sticking, using a setup with the St. Petersburg ionization chamber. These data mark a significant improvement in reliability and may clarify questions concerning previous discrepancies. The new results is _s(0.56±0.04)%, lower than the theory prediction _s=(0.65±0.03)%, at medium density.     

Features of the Fossil Tidal Bulge Formation for the Early Moon

Doklady Physics - The limitations imposed on the orbit and the distribution of the density of the early Moon by present-day measurements of its fossil tidal bulge are studied. A semi-analytical...