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High frequency vibration monitoring and diagnostics of high-speed pump rolling bearings

Litvinov D., Rudzitis J.

Acta Mechanica et Automatica

2008

Vol. 2, no. 3

76-79

Evolution of modern industry makes great demands to reliable work of pump equipment with large revolutions number of rotating parts. Under special supervision must be the centrifugal high-speed pumps. One of the major and hardly loaded units of high-speed pump equipment are rolling bearings, therefore it is very important to conduct monitoring and early diagnostics works to find out defects in them. For the high-frequency vibration detection and analysis it is possible to use both stationary and portable systems of monitoring and diagnostics. This diagnostics advantage is early detection of aberration from normal operation of rolling bearings and transition from equipment service and repair on-schedule to real situation service and repair, which is determined on periodic diagnostics results.

Investigation of segregation by quantitative transmission electron microscopy

Schowalter M., Rosenauer A., Litvinov D., Gerthsen D.

Optica Applicata

2006

Vol. 36, nr 2-3

297-309

The segregation effect occuring during molecular beam epitaxy and metalorganic vapour phase epitaxy growth of ternary III-V semiconductor heterostructures was investigated by quantitative transmission electron microscopy (QTEM) and by simulation of optical properties. The concentration distribution of various III-V semiconductor heterostructures was measured by QTEM and averaged along the direction perpendicular to the growth direction. Resulting concentration profiles could be well fitted using the model of Muraki et al. (Muraki K., Fukatsu S., Shiraki Y., Ito R., Appl. Phys. Lett. 61(5), 1992, p. 557) yielding the segregation efficieny R. For the investigation of the effect of segregation on the photoluminescence, concentration profiles for different segregation efficiencies were simulated and photoluminescence peak energies were derived by solving Schrödinger's equation for spatially varying potentials deduced from the measured concentration profiles.