Propagation of a Gaussian beam in a layered periodic structure is studied analytically, numerically, and experimentally. It is demonstrated that for a special set of parameters the acoustic beam propagates without diffraction spreading. This propagation is also accompanied by negative refraction of the direction of phase velocity of the Bloch wave. In the study of two-dimensional viscous phononic crystals with asymmetrical solid inclusions, it was discovered that acoustic transmission is nonreciprocal. The effect of nonreciprocity in a static viscous environment is due to broken PT symmetry of the system as a whole. The difference in transmission is caused by the asymmetrical transmission and dissipation. The asymmetrical transmission is caused solely by broken mirror symmetry and could appear even in a lossless system. Asymmetrical dissipation of sound is a time-irreversible phenomenon that arises only if both energy dissipation and broken parity symmetry are present in the system. The numerical results for both types of phononic crystals were verified experimentally. Proposed devices could be exploited as collimation, rectification, and isolation acoustic devices.

A novel electric machine design, similar to an axial flux machine, incorporates hydrostatic bearings to increase efficiency and stability of said machine. In this thesis, the feasibility of a hydrostatic solution is explored and evaluated by development, manufacturing, and assembly of a test rig, as well as running experimental tests with it. The experiments are designed to measure viscous losses in the contact area between a rotor disc and stator bearing pads, where the oil fil thickness is below 0.1 mm, simulating low rpm (50-150 rpm) working condition of a 1:1 scale simplified model of the novel machine. The effects on the viscous losses by the hydraulic oil film thickness, rotor disc speed and oil pump pressure are analyzed and compared with an analytical model provided by the inventing startup company. A regression analysis model based on the experimental data is also presented. / En ny elektrisk maskinkonstruktion, lik en axialflödesmaskin i design, innefattar hydrostatiska lager för att öka verkningsgraden och stabiliteten hos den nämnda maskinen. I detta examensarbete undersöks och utvärderas genomförbarheten av en hydrostatisk lösning genom utveckling, tillverkning och ihopmontering av en testrigg, samt genom att köra experimentella test med riggen. Experimenten är utformade för att mäta viskösa förluster i kontaktområdet mellan en rotorskiva och statorlager, där oiljefilmstjockleken är under 0.1mm, genom att simulera ett arbetstillstånd i modell skala 1:1 av för en förenklad variant av den nya maskinen, under lågt varvtal (50–150 rpm). Effekterna på de viskösa förlusterna av den hydrauliska oljefilmens tjocklek, rotorskivans hastighet och oljepumpens tryck analyseras och jämförs med en analytisk modell given av det uppfinnande startupföretaget.