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1.
We consider the isothermal flow through a cylindrical flat chamber, a model of some particular heat exchanger, for which LDV measurements and a numerical simulation have been performed. Experimental results show the establishment of an important vortex zone, the secondary flow extending all along the chamber radius. This observation leads to an expected significant increase of the fluid mixing. Results issued from the numerical simulation appear to be in close agreement with experimental data. Nevertheless, the k–ε model used here must be improved to obtain a better approach near the vortex centre. To cite this article: S. Petitot et al., C. R. Mecanique 330 (2002) 593–599. 相似文献
2.
In this paper, the possibility of using the gradients of the temperature and of the internal parameters as additional state variables in Continuum Thermodynamics is considered. The expressions of the two principles are discussed and Clausius–Duhem inequality is derived under an appropriate statement of the internal entropy production. Several formulations are proposed and compared to existing results in the literature. To cite this article: P. Ireman, Q.S. Nguyen, C. R. Mecanique 332 (2004). 相似文献
3.
The steady-state two-phase flow non-linear equation is considered in the case when one of phases has low effective permeability in some periodic set, while on the complementary set it is high; the second phase has no contrast of permeabilities in different zones. A homogenization procedure gives the homogenized model with macroscopic effective permeability of the second phase depending on the gradient and on the second order derivatives of the macroscopic pressure of the first phase. This effect cannot be obtained by classical (one small parameter) homogenization. To cite this article: G.P. Panasenko, G. Virnovsky, C. R. Mecanique 331 (2003). 相似文献
4.
Urine transport is made from the kidney to the bladder through the ureter by isolated pockets called bolus. To determine the urine flow in a bolus, we use an adherence condition on the interface urine/wall. It gives us an infinite linear system verified by a set of parameters. An iterative and convergent algorithm allows us to solve this system and to determine analytically the components of the velocity vector in the bolus. To cite this article: A. Vogel et al., C. R. Mecanique 332 (2004). 相似文献
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6.
J. Umemura 《Journal of Molecular Structure》1977,36(1):35-54
Temperature dependence of the IR spectra of crystalline propionic acid were examined in the temperature range 242–50 K. The intensities of most absorption bands increased on lowering the temperature, but some bands diminished until they disappeared at temperatures lower than about 120 K. Normal coordinate analyses indicate that the former bands are due to the stable cis dimer and the latter due to the less stable trans dimer which would be produced from the cis dimer by simultaneous proton transfer along two hydrogen bonds. 相似文献
7.
H. Nickel und R. Schaeps 《Fresenius' Journal of Analytical Chemistry》1976,281(3):193-199
Zusammenfassung Es wird über die Beeinflussung spektrochemischer Ergebnisse durch homogene Magnetfelder und Zusatzsubstanzen bei Lichtbogenanregung berichtet. Der Einfluß eines homogenen Magnetfeldes auf die Gesamtintensität der Linien verschiedener Analysenelemente (Hg, Zn, Ga, Tl) in Graphit wurde untersucht. Außerdem wurden die axialen und radialen Verteilungen der Linienintensitäten im Bogenplasma bestimmt. Als Parameter dienten die Magnetfeldstärke (0, 0,01, 0,02, 0,04 T) und die physikalischen Daten der Analysenelemente. Dabei wurde festgestellt, daß die Wirkung des Magnetfeldes vom Ionisationspotential der beteiligten Elemente, von ihrer Atommasse und von der angewendeten Magnetfeldstärke abhängig ist.Weiterhin wurde der Einfluß eines homogenen Magnetfeldes auf die Verdampfungsrate mit Hilfe einer kontinuierlich und zerstörungsfrei arbeitenden Meßmethode untersucht. Es zeigte sich, daß die Verdampfungsrate bei Anwendung eines Magnetfeldes in Abhängigkeit von der Verdampfungswärme der Elemente erhöht wird.Die Auswirkung der Zusatzsubstanz Ga2O3 auf die Linienintensitäten der Verunreinigungen wird von der Ga2O3-Konzentration und vom Ionisationspotential der untersuchten Elemente beeinflußt.
On the influence of additives and homogeneous magnetic fields on the arc as a spectrochemical source of excitationI. Spectrochemical investigations in graphite mixtures
The paper deals with homogeneous magnetic fields and added chemical substances both affecting the spectrochemical results obtained in arc excitation studies. The influence of a homogeneous magnetic field on the total intensity of lines of various analysis elements (Hg, Zn, Ga, Tl) in graphite has been examined. Furthermore, the axial and radial distributions of line intensities in arc plasma were determined. Parameters used were the magnetic field strength (0, 0.01, 0.02, 0.04 T) and the physical data of the analysis elements. It was found that the effect of the magnetic field varies with the ionization potential of the elements involved, their atomic mass and the strength of the magnetic field applied.A non-destructive method of measuring was introduced for studying the effects of a homogeneous magnetic field on the rates of evaporation. The results showed increased evaporation rates in presence of magnetic fields as a function of the evaporation heat of the elements involved.Effects of Ga2O3 additive on the line intensities of impurity elements are governed by the Ga2O3 concentration and the ionization potential of the elements examined.相似文献
8.
H.-J. Gräbner 《Fresenius' Journal of Analytical Chemistry》1978,293(4):301-302
9.
10.
B. Gillot F. Bouton J.F. Ferriot F. Chassagneux A. Rousset 《Journal of solid state chemistry》1977,21(4):375-385
When Fe3+ ions are substituted by aluminum or chromium on magnetite octahedral sites, the ir spectrum shows the conversion of an inverse spinel to a normal spinel. Both broad bands of magnetite are gradually replaced by the four characteristic bands of normal spinels II–III. They are also observed for solid solutions, FeCr2O4FeAl2O4, with, however, a further band at 780 cm?1 which may be assigned to Al3+ ions on tetrahedral sites. Low-temperature (<400°C) oxidation of these compounds whose sizes are less than 2000 Å results in lacunar spinels III–III. The ir spectrum of these solids is characterized by two absorption bands (as for inverse spinels II–III) except for compounds close to pure γFe2O3 in which an order of vacancies could be put in evidence. 相似文献