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141.
LI Le-Min LIU Yi WANG Xiu-ZhenDepartment of Chemistry Peking University Beijing China 《中国化学》1994,12(5):403-413
An iterative procedure is proposed to facilitate the determination of molecular vi-brational force constants from the experimental fundamental frequencies. Proper restrictions are introduced to the force constants based on physical considerations for getting reasonable results. The experimental data of Coriolis coupling coefficients and isotopic frequency shifts are utilized to reduce the uncertainty of the calculated force constants when they are available. A series of various kinds of molecules have been calculated by this method and the results are satisfactory. 相似文献
142.
143.
144.
Study of force-dependent and time-dependent transition of secondary flow in a rotating straight channel by the lattice Boltzmann method 总被引:1,自引:0,他引:1
A numerical study using the lattice Boltzmann method has been carried out for flow through a rotating straight channel with a rectangular cross section. With different forces applied, the secondary flow exhibits two-cell states, four-cell states or six-cell states at a range of low rotational Reynolds number, however, within which only the two-cell states have been commonly reported. In addition to the force-dependent flow transition, a time-dependent flow transition of the secondary flow among two-cell states, four-cell states and six-cell states is also discovered during flow development. These newly found flow transitions and their regulations by force application have been analyzed. Based on numbers of case studies, it is found that a dimensionless number, the ratio of the driving pressure gradient to the centrifugal force, regulates such flow transitions. This study not only releases new phenomena of flow transition, but also indicates new applications in flow control, particle separation and heat transfer. 相似文献
145.
The Fourier transform infrared spectrum of gaseous thiophene, C4H4S, has been recorded in the 600-1200 cm−1 spectral region with a resolution of ca. 0.0030 cm−1. Five fundamental bands ν13 (B1, 712.1 cm−1), ν7 (A1; 840.0 cm−1), ν6 (A1; 1036.4 cm−1), ν5 (A1; 1081.5 cm−1) and ν19 (B2; 1084.0 cm−1) have been analysed by the standard Watson model (A-reduction). Ground state rotational and quartic centrifugal distortion constants have been obtained from a simultaneous fit of ground state combination differences from four of these bands and previous microwave transitions. Upper state spectroscopic constants have been obtained for all five bands from single band fits using the Watson model. A strong c-Coriolis resonance perturbs the close lying ν5 and ν19 bands. We have analysed this dyad system by a model including first and second order Coriolis resonance using the theoretically predicted Coriolis coupling constant . From this analysis we locate the previously unobserved ν19 band at 1083.969 cm−1. The rotational constants, ground state quartic centrifugal distortion constants, anharmonic frequencies, and vibration-rotational constants (α-constants) predicted by quantum chemical calculations using a cc-pVTZ basis with B3LYP methodology, are compared with the present experimental data, where there is generally good agreement. A complete set of anharmonic frequencies and α-constants for all fundamental levels of the molecule is given. 相似文献
146.
The drift of spheres in a rotating fluid is investigated. The problem is studied experimentally and numerically using the Galerkin method. It is shown that for small angular velocities of the fluid Ω the drift velocity of the spheres is almost independent of Ω, but once a certain threshold value Ω* is attained the drift velocity rapidly decreases. The experimental dependence of the translational velocity of the sphere on the fluid angular velocity is explained on the basis of a theoretical analysis. 相似文献
147.
Antje Brucks 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(1):33-47
Experimental results are presented on natural convection in a spherical shell of inner and outer radii r
1 = 14 mm and r
2 = 35 mm, with the inner sphere cooled and the outer sphere heated. The fluids filling the shell are two different silicon
oils having Prandtl numbers 39 and 233. Both spheres are fixed together and can be rotated. In the studied regime, both Coriolis
and centrifugal forces become significant. For sufficiently small Rayleigh numbers the resulting flow pattern is axisymmetric
and steady, consisting of a plume descending from the south pole of the inner sphere, and returning in the equatorial regions.
For greater Rayleigh numbers the flow becomes non-axisymmetric, with azimuthal modes m = 2 to 4 arising. We map out the critical Rayleigh number for the onset of these different modes, and consider how they vary
with increasingly rapid overall rotation. Detailed flow measurements are done by converting a standard 2D particle image velocimetry
system into a scanning quasi-3D PIV system. 相似文献
148.
A. I. Skotnikov 《Journal of Applied Spectroscopy》1997,64(2):265-271
The most important aspects in solving inverse and direct spectroscopic problems in the second order of perturbation theory
in the presence of Coriolis, Fermi, and Darling-Dennison resonances are discussed. A scheme for obtaining unperturbed values
of spectroscopic parameters is suggested which has some advantages over that proposed earlier in [6]. It is believed that
this information can be useful to specialists in the field of applied spectroscopy.
Saratov State Technical University, 77, Politechnicheskaya St., Saratov, 410054, Russia. Translated from Zhurnal Prikladnoi
Spektroskopii, Vol. 64, No. 2, pp. 249–255, March–April, 1997. 相似文献
149.
A finite element solution is developed for a penalty function formulation of the equations which govern the steady motion of a Newtonian fluid through a pipe that rotates about an axis not parallel to its own. The motion in this system is driven by the Coriolis acceleration, which has components in the axial direction as well as in the transverse plane of the pipe. The relative magnitudes of these components significantly affect the qualitative and quantitative nature of the primary and secondary flow field. The present results compare favourably with those of previously reported experimental and theoretical studies over a wide range of flow regimes. 相似文献
150.
Synchrotron radiation from the new Canadian Light Source facility has been used to obtain a high resolution (0.0012 cm−1) absorption spectrum of acrolein vapor in the 550-660 cm−1 region. Almost 2000 transitions have been included in a detailed analysis of the ν12 (∼564 cm−1) and ν17 (∼593 cm−1) fundamental bands which yielded precise values for the band origins, rotational and centrifugal distortion parameters. The analysis included the a- and b-type Coriolis interactions connecting ν12 and ν17, as well as an a-type Coriolis interaction between ν17 and a “dark” perturbing state, identified as 4ν18. We believe that this is the first high resolution infrared study of acrolein. 相似文献