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Mathematical Study of the Small Oscillations of a Spherical Liquid Bridge Between Two Equal Disks Under Gravity Zero

100%

Vivona D.

2001

tom vol. 49, nr 1

31-49

This paper deals with the mathematical study of the problem of small oscillations of a liquid bridge with a free surface, held together by surface tension, between two rigid coaxial disks, under gravity zero, in the case of a spherical liquid bridge in the equilibrium position. The equation which gives the displacement of the free surface, is reduced to a variational equation. After a careful discussion, it can be shown that the bilinear form which appears in the equation, is always coercive. Then, the existence of the eigenfrequencies of the liquid mass can be proved by means of the method of the functional analysis.

Reduced gravity testing and research capabilities at new 2.0 second drop tower

63%

Steinberg T.

2008

tom Vol. 31, nr 2

822-826

Purpose: The Queensland University of Technology's has recently (2006) decommissioned a 1.9 second drop tower adapted for operation within an unused lift well of a building and has fabricated a purpose built, stand alone 2.0 second drop tower specifically to accommodate reduced gravity experimentation and manufacturing. The specifications and operational procedures of this new research facility are presented along with information regarding the expected benefits of manufacturing in a reduced gravity environment with focus on the production of metallic materials and nanomaterials production (including silica sol-gels and carbon nanotubes). Opportunities will also be discussed regarding both collaborative research and the provision of reduced gravity test or manufacturing services. Design/methodology/approach: The operational characteristics of a reduced gravity testing facility located in the School of Engineering Systems at Queensland University of Technology (QUT) are described. The Phenomena in Microgravity Laboratory (PML) operates the tower, and runs several research programs investigating gravity dependent phenomena. Several of these programs are outlined in this paper in the areas of combustion, fluid dynamics and nanomaterials. Findings: Calibration of the QUT drop tower has been performed, and it is currently used to conduct research in diverse disciplines with novel and useful results being obtained. Practical implications: Reduced gravity experimentation is important to many research groups working in various fields investigating both fundamental and applied aspects of diverse physical phenomena. Very few terrestrial or extra-terrestrial experimental facilities are currently available that allow researchers or manufacturers access to reduced gravity environments for their work. Originality/value: The QUT drop tower provides an economical and accessible reduced-gravity facility for use by scientists and industry both nationally and internationally.

Mikrograwimetryczna ocena zagrożenia powierzchni terenu nie zlikwidowanymi szybami górniczymi

63%

Fajklewicz Z. , Radomiński J.

1999

tom Vol. 44, nr 3

293-305

W pracy przedstawiono wyniki badań teoretycznych mających na celu określenie zakresu mikrograwimetrycznej metody wykrywania i oceny stopnia zagrożenia powierzchni terenu dla obszarów występowania prawdopodobnie zlikwidowanych szybów górniczych. Dokonano analizy metody tak pod kątem parametrów geometrycznych szybów, jak i stopnia ich podsadzenia - likwidacji. Przedstawiono praktyczne przykłady zastosowania metody mikrograwimetrycznej dla trzech szybów zlokalizowanych w odrębnych obszarach górniczych i o różnych stopniach likwidacji.

In the paper the theoretical and experimental results of the microgravity research are presented. The mean goal of this works were to applied the microgravity measurements for detection of the old unfilled mine shafts. The next stage of the work was to find the relation between the shaft's parameters, density of material probable used to fill in the shaft, density of the microgravity points of the gravity pictures. The are presented three examples of application gravity method for estimation of the stage of filled in of the shafts. The shafts come from different areas of mine region. The first example is related to, shaft Rubin located in Piekary Śląskie. The negative extreme of the residual gravity microanomalies is presented on Fig. 5. It is near by the gravity point no 9 and derives from old compressed old shaft so is confirmed by georadar measurements (Fig. 7). The picture of the microgravity anomalies presented on Fig. 8 corresponds to unfilled old shaft Maria-Anna. On the base of gravity data it is possible to estimate of the hazardous area and state of the ground surface due to existence of the unfilled shaft. The distribution of the microgravity anomalies in profile (Fig. 10) presents the negative anomaly over the air-shaft I in coal mine Saturn-Czeladź. The negative gravity anomaly over the shaft corresponds to unfilled shaft with dilatation below the concrete plate over the shaft.