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991.
E. W. C. van Groesen 《Flow, Turbulence and Combustion》1981,37(1-2):53-65
992.
993.
J. van der Hurk Tj. Hollander C.Th.J. Alkemade 《Journal of Quantitative Spectroscopy & Radiative Transfer》1974,14(11):1167-1178
Experiments are described to yield more decisive information about the excitation energies of visible strontium monohydroxide bands appearing in flames. Excitation energy differences are derived directly from the ratio of thermal band intensities measured as a function of temperature. Absolute excitation energies are derived from the temperature dependence of the ratio of thermal band to strontium line intensity, while assuming a value for the dissociation energy of SrOH. Flames with temperatures ranging from 1907 to 2886 K were used. A level diagram is proposed for the strontium bands at 6060, 6470, 6690, and 6820 Å. From the results obtained, two conclusions may be drawn: (i) the bands considered are non-resonance bands and (ii) the uncertainty in the excitation energy as a result of the unknown molecular configuration is 0·25 eV. 相似文献
994.
It is demonstrated that the isomer shift of Mössbauer nuclei in transition metal alloys can be quantitatively described in terms of an atomic cell model. The isomer shift ΔE, relative to the pure metal as a reference, is derived from a change in boundary conditions for the atomic cell; , where ø1 is the electronegativity parameter, nws the cell boundary electron density and P and Q are constants for a given Mössbauer nucleus. For solid solutions there is in addition a relatively small size mismatch term. 相似文献
995.
G. Ooms A. Segal A.J. van der Wees R. Meerhoff R.V.A. Oliemans 《International Journal of Multiphase Flow》1983,10(1):41-60
A theoretical model has been developed for core-annular flow of a very viscous oil core and a water annulus through a horizontal pipe. Special attention was paid to understanding how the buoyancy force on the core, resulting from any density difference between the oil and water, is counterbalanced. This problem was simplified by assuming the oil viscosity to be so high that any flow inside the core may be neglected and hence that there is no variation of the profile of the oil-water interface with time. In the model the core is assumed to be solid and the interface to be a solid/liquid interface.By means of the hydrodynamic lubrication theory it has been shown that the ripples on the interface moving with respect to the pipe wall can generate pressure variations in the annular layer. These result in a force acting perpendicularly on the core, which can counterbalance the buoyancy effect.To check the validity of the model, oil-water core-annular flow experiments have been carried out in a 5.08 cm and an 20.32-cm pipeline. Pressure drops measured have been compared with those calculated with the aid of the model. The agreement is satisfactory. 相似文献
996.
E. H. du Marchie van Voorthuysen G. L. Zhang H. de Waard 《Hyperfine Interactions》1983,16(1-4):1025-1028
Sideband intensities and quantum beats were measured for recoillessly emitted gamma rays as a function of the vibration frequency of quartz crystals on which sources of129mTe and57Co were deposited. At most frequencies a low degree of coherence of the vibrations of the source nuclei was observed. 相似文献
997.
C.A.A. van Boeckel J.P.G. Hermans P. Westerduin J.J. Oltvoort G.A. van der Marel J.H. van Boom 《Tetrahedron letters》1982,23(18):1951-1954
The application of two new phosphorylation procedures enabled us to synthesize an analog of Lipid A. 相似文献
998.
T.G.M. van de Ven 《Advances in colloid and interface science》1982,17(1):105-127
Recent progress in experimental and theoretical developments dealing with colloidal. interactions between two spheres in shear flow is reviewed. A systematic comparison is made between spheres suspended in simple electrolyte and in cationic polyelectrolye solutions. Microrheological observations, performed with the traveling microtube, make an in-depth investigation possible of the colloidal forces and the mechanisms of polymer bridge formation. Reasons are discussed for the often-observed aging of colloidal aggregates. Finally, coagulation rates are presented for systems with weak and strong Brownian motion. It is shown that the often-used assumption of additivity of the ortho- and perikinetic coagulation rates is incorrect. 相似文献
999.
Problems in scaling-down procedures of chemical analysis are generally stated. Titrations are to be preferred over single measurements. Continuous titration in a titration system may help in solving the stated problems. Detection is easy and may be done by simple electrodes. Illustrations from the authors' practice are given. 相似文献
1000.