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1

Diffraction methods of drop size measurement in polydispersive media

Opara T.A.

Optica Applicata

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2001

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Vol. 31, nr 1

115-141

EN

The principles of the diffractive method of drop size determination in the aerosol stream of fuel of significant diversification of drop dimensions are presented. Three variants of data processing obtained from the light intensity distribution I(r) in the image plane are described. A comparison of both properties and applicability of the two variants is made.

2

Modelling of multilayered dispersive and dissipative media

Narayan J.

Acta Geophysica Polonica

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2000

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Vol. 48, nr 3

347-358

EN

This paper presents a frequency domain formulation in agreement with Futterman's third absorption-dispersion relationship, for synthesizing normal incident seismograms for a layered elastic and dissipative media. In the past, synthetic seismograms have been computed in time and frequency domains using attenuation and dispersion phenomena separately as well as simultaneously. The time domain modeling suffers from minimum phase formulation and inadequate treatment of dispersion. Amplitude and phase spectra have been computed using the ratio of spectra of upgoing and downgoing waves in the layers and Fast Fourier Transform (FFT) technique bas been adopted for converting the response in time domain. The results have revealed changes in the reflected wave forms in both frequency and time domains in accordance with the theory of absorption and dispersion phenomena. Results with constant quality factor depict an increase in both attenuative and dispersive effects with a decrease in the quality factor. Frequency dependent and independent quality factors were considered and almost similar responses have been obtained. The time lead caused by dispersion is found to be much smaller when the reference frequency is at the center of the desired frequency band. It has also been observed that the time lead or delay caused by dispersion increases with the travel time. Key words: synthetic seismograms, dispersive media, dissipative media, quality factor.

3

Linear disturbances and critical conditions in one – dimensional flow of constans media

Bilicki Z., Downar-Zapolski P.

Zeszyty Naukowe Instytutu Maszyn Przepływowych Polskiej Akademii Nauk w Gdańsku

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1999

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nr 505/1464

63--83

EN

This paper investigates the influence of inertial processes on the of small disturbances and the properties of the critical flow of continuos media. The intertial processes may stem from heat and mass exchange on the component two-phase flow. Since almost all the models of a flow medium take the form of hyperbolic, quasi-linear systems of partial-differential equations, the mathematical background of the critical flow and the propagation of linear disturbances, for this type of equations, is presented. The problem of discontinuous solutions and its possible influence on the critical flow has been discussed Finally, some important differences concerning linear waves in dispersive and non-dispersive systems are discussed.

4

The speed of sound in the homogeneous vapour-liquid mixture

Downar-Zapolski P., Bilicki Z., Kwidziński R.

Archives of Thermodynamics

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1998

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Vol. 19, no 1/2

5-31

EN

This paper investigates the influence of non-equilibrium phase transition in the vapour-liquid mixture on the properties of sound waves. A dispersion relation for small disturbances has been found and analysed. The investigation of evolution of a linear wave in the vapour-liquid mixture creates the background for conclusions concerning a speed of sound in dispersive media.