The article deals with a research of acoustic emission induced by electromagnetic field. Experiments were focused on measurement of acoustic emission (sound waves) as a mechanical response to the excitation current. Surface displacement was detected by laser interferometer and arising surface waves were then observed. Maximal measured amplitude of mechanical displacement driven by excitation current with amplitude 120 mA is about 8 nm. and Článek se zabývá výzkumem akustické emise generované pomocí elektromagnetického pole. V experimentech se měří velikost mechanické odezvy akustické emise (mechanických vln) na budicí proud z generátoru. Výchylka povrchu byla snímána laserovým interferometrem, byla registrována přítomná povrchová vlna. Maximální amplituda výchylky je 8 nm při amplitudě budicího proudu 120 mA.
This paper contains the studies of the noise level in GPS (Global Positioning System) time series. As the data for this research the authors used changes of the geodetic coordinates of the ASG-EUPOS and associated (Slovak and Czech) sites. The method of precise GPS observations processing in short-time intervals was worked out in the Centre of Applied Geomatics, Military University of Technology. The authors focus on the diurnal and sub-diurnal frequency bands (tidal) as the tidal effects influence the sites’ positions at the most and the model used in the standard processing software does not contain geodetic coefficients. Thus the residual values of the geodetic coordinates time series should hold some information in the shape of coloured noise. The paper comprise short description of the Earth tides phenomenon, the concept of the tidal parameters determination, character of the white and coloured noise and the assessment of the noise estimation from GPS data. As the processed network contains 130 sites the spatial distribution of the noise’s parameters is also investigated., Janusz Bogusz and Bernard Kontny., and Obsahuje bibliografii
The paper deals with the measurement of coherent light power below the noise level of one detector. The method uses the optical arrangement of the Mach-Zehnder interferometer and the modified detector in the quadrature. Using correlated detection of signals in two quadrant detector channels, the measured power was 23 times weaker than the noise-equivalent power. and Článek se zabývá měřením výkonu koherentního světla pod úrovní šumu jednoho detektoru. Měřicí metoda využívá optického uspořádání Machova-Zehnderova interferometru a upraveného detektoru v kvadratuře. Pomocí korelované detekce signálů ve dvou kanálech detektoru v kvadratuře se podařilo naměřit výkon 23krát slabší, než je ekvivalentní šumový výkon.