Acousto-Optic Diffraction by Shear Horizontal Surface Acoustic Waves in 36° Rotated Y-Cut X-Propagation Lithium Tantalate

We have investigated the acousto-optic diffraction by shear horizontal surface acoustic waves in 36° rotated Y-cut X-propagation lithium tantalate ($LiTaO_3$) crystals. The measurements were performed at the optical wavelength 633 nm of He-Ne laser and acoustic wavelengths of 50-60 μ m. The anisotropic diffraction with the light polarization rotation in the transmission mode was observed. The measured and calculated values of the light incidence angle corresponding to the strongest diffraction differed significantly. A narrow strip of a thin metal film deposited on the crystal surface drastically affected the light diffraction. We attribute these effects to the conversion processes between the shear horizontal leaky surface acoustic wave and shear horizontal surface skimming bulk wave

Research on Aeration Systems Efficiency in Small Wastewater Treatment Plants

<p>Large amount of small wastewater treatment plants does not work properly. One of the reasons could be wrong design of the aeration system. Therefore, the aim of this research is to analyse the performance of two aeration systems used in Lithuanian small wastewater treatment plants. Both aeration systems are designed for the following parameters: 4 PE and 0,8 m³/d wastewater flow. These data correspond to the oxygen requirement of 40,9 g O₂/h. Summarizing the results of the research, it was found out that the capacity of both aerators was insufficient to satisfy the oxygen requirement and ensure proper biological treatment of wastewater.</p><p>Article in Lithuanian</p

Acoustoelectric investigation of V2O5·nH2O thin film transition from wet gel to xerogel

The strong acoustoelectric interaction in thin films of vanadium pentoxide hydrate (V2O5·nH2O) fabricated by the sol–gel method on the YZ LiNbO3 substrate was investigated using the surface acoustic wave (SAW) technique. Significant variations of the SAW amplitude and phase during a few first hours after the structure fabrication were attributed to the changes in the film conductivity linked to the water loss in the V2O5·nH2O films during the transition process from wet gel to xerogel. The SAW measurements revealed that the conductivity of vanadium pentoxide hydrate films linearly increased with time as the water amount, n, in V2O5·nH2O decreased according to a logarithmic law from 8 to 6.3. The estimated interlayer distance between V–O layers in the hydrate structure was 23 Å–21 ÅFizinių ir technologijos mokslų centro Puslaidininkių fizikos institutasVilniaus universitetasVytauto Didžiojo universitetasŠvietimo akademij

Investigation of a GaN-Based SAW Oscillator with respect to UV Illumination and Temperature

Oscillation frequency of a GaN-based surface acoustic wave delay-line oscillator is investigated in the temperature range from -20°C to +38°C, with and without UV illumination. The results imply that such an oscillator may be used for temperature sensing with the resolution of up to 1 mK. On the other hand, as the frequency downshift due to UV illumination does not exhibit a significant dependence on temperature, it may be expected that such a system, when used as a UV sensor, would not require applying a correction for temperature