INFLUENCE OF A LEVELNESS DEFECT IN A THRUST BEARING ON THE DYNAMIC BEHAVIOUR OF AN ELASTIC SHAFT

This paper examines the non-linear dynamic behaviour of a flexible shaft. The shaft is mounted on two journal bearings and the axial load is supported by a defective hydrodynamic thrust bearing at one end. The defect is a levelness defect of the rotor. The thrust bearing behaviour must be considered to be non-linear because of the effects of the defect. The shaft is modelled with typical beam finite elements including effects such as the gyroscopic effects. A modal technique is used to reduce the number of degrees of freedom. Results show that the thrust bearing defects introduce supplementary critical speeds. The linear approach is unable to show the supplementary critical speeds which are obtained only by using non-linear analysis.     

Global Analysis of the Flows of Fluids with Pressure-Dependent Viscosities

 To describe the flows of fluids over a wide range of pressures, it is necessary to take into account the fact that the viscosity of the fluid depends on the pressure. That the viscosity depends on the pressure has been verified by numerous careful experiments. While the existence of solutions local-in-time to the equations governing the flows of such fluids are available for small, special data and rather unrealistic dependence of the viscosity on the pressure, no global existence results are in place. Our interest here is to establish the existence of weak solutions for spatially periodic three-dimensional flows that are global in time, for a large class of physically meaningful viscosity-pressure relationships. (Accepted May 1, 2002) Published online November 15, 2002 Communicated by S. S. ANTMAN     

Fiber-Optic Backscattering Profile Measurements for Determination of the Optical Coefficients of Turbid Media

The necessity of using anisotropic approximation in techniques for determining optical parameters from the backscattered radiation profile is shown. A fiber-optic technique for simultaneous determination of the anisotropy parameter as well as the scattering and absorption coefficients of turbid media is proposed. It is based on the comparison of the experimental backscattered radiation profiles and those obtained by the numerical Monte Carlo method.     

Spectrophotometric Determination of Proline in Aqueous Solutions

The spectrophotometric determination of proline in aqueous solutions was studied. It was shown that pH, concentration, and time of storing the solution affect its spectral properties.__________Translated from Zhurnal Analiticheskoi Khimii, Vol. 60, No. 8, 2005, pp. 802–805.Original Russian Text Copyright © 2005 by Davydova, Kotova, Krysanova, Selemenev.     

Synthesis and crystal structural study of ternary molybdate NaMg3In(MoO4)5

We have synthesized single crystals of a temary molybdate NaMg₃In(MoO₄)₅ and cam'ed out an X-ray structural study (a KM-4 automatic difiactometer, MoK, radiation, 4503 F, R = 0.047). The triclinic unit cell dimensions are a = 7.0476(7), b = 17.935(2), c = 6.9849(7)Å, = 87.650(9), = 100.980(8), = 92.510(9)°, V= 865.5(2) A³, Z = 2, and space group P^–1. The crystal structure involves MoO₄ tetrahedra and (Mg, In)0₆ octahedra forming a three-dimensional framework with Na atoms located in its cavities. The compound melts at 990°C with decomposition.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences. Institute of Physics, Siberian Branch, Russian Academy of Sciences. Buryatian Institute of Natural Sciences, Siberian Branch, Russian Academy of Sciences. Translated fromZhurnal Strukturnoi Khimii, Vol. 34, No. 5, pp. 147–151, September–October, 1993.Translated by T. Yudanova     

Solution and gas-phase synthesis of the heteroligand yttrium complex with dipivaloylmethane and bis(salicylidene)ethylenediamine Y(dpm)(salen)

The interaction of yttrium dipivaloylmethanate Y(dpm)₃ with bis(salicylidene)ethylenediamine (H₂salen) in solution and the gas phase leads to the formation of the heteroligand complex Y(dpm)(salen). The composition of the product has been confirmed by IR spectroscopy, ¹H NMR, and elemental analysis. The introduction of a Schiff base excess into the solution or gas phase does not result in the formation of the homoleptic complex Y₂(salen)₃.     

Thermodynamics of liquid Fe-Si and Fe-Ge alloys

The enthalpies of mixing of liquid binary Fe-Ge (1765±5 K) and Fe-Si (1750±5 K) alloys were determined using a high-temperature isoperibolic calorimeter. The thermodynamic properties of Fe-Ge melts were also studied by electromotive force method in the temperature range of 1250-1580 K. The comparison of our measurement results with literature data has been performed. The extreme negative values of integral enthalpy of mixing and alternating-sign deviations from Raoult's low for germanium can be explained by the influence of binary clusters formation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Decreasing the Content of Free Formaldehyde in Urea-Formaldehyde Resins

The possibility of decreasing the content of free formaldehyde in urea-formaldehyde resins by varying the pH and urea-formaldehyde ratio in various synthesis steps was examined. Urea-formaldehyde resins containing no free formaldehyde were prepared.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 4, 2005, pp. 692–694.Original Russian Text Copyright © 2005 by V. Maslosh, Kotova, O. Maslosh.     

1,2-Dimethylimidazobenzo-1′, 2′, 3′-thiadiazoles and derived cyanine dyes

New tricylic heterocyclic systems and their methyl derivatives are synthesized. They are 2-methylimidazo[5, 4-e]benzo-1, 2, 3-thiadiazole, 2-methylimidazo[5, 4-g]benzo-1, 2', 3-thiadiazole, 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole, and 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole. Quaternary salts of the 1, 2-dimethyl derivatives are used to prepare symmetrical and unsymmetrical trimethinecyanines and dimethinemerocyanines containing rhodanine groups. The absorption maxima of the dyes are displaced towards the long wavelength region compared with imidacarbocyanines. It is shown that when 1, 2-dimetnyl-5-aminobenzoimidazole is thiocyanated, the thiocyano group enters the benzoimidazole ring at position 4, and that 1, 2-dimethylimidazo[5, 4-e] benzo-1, 2, 3-thiadiazole is less basic than its isomer 1, 2-dimethylimidazo[5, 4-g]benzo-1, 2, 3-thiadiazole.     

On the nature of optically controlled delay of a stokes pulse amplified by stimulated Brillouin scattering in optical fiber

In this work we show through an analytic solution of the set of two coupled dynamic equations for the slowly varying amplitudes of the Stokes optical field and material density in stimulated Brillouin scattering (SBS), its analysis and a set of experiments, that the SBS-induced delay of an output Stokes pulse which is amplified by the SBS interaction is due exclusively to the inertia of the acoustic wave excitation.