[en] The effect of two main regimes of the anisotropic Bragg acoustooptic (AO) diffraction on the coherence degree of an optical field from the point of view of the number of acoustic grating layers intersected by an optical beam is analysed. It is shown based on the AO interaction in a TeO₂ single crystal that despite a substantial difference (approximately by five times) between acoustic frequencies used in the regimes of large and small angles of light incidence with respect to the acoustic wave front, the character of the speckle pattern is almost the same. (coherence)

[en] The aim of the work is to ascertain a solar car battery performance. The student engineering team of Peter the Great Petersburg Polytechnic University designs the car. Parameters as terminal voltage, operating current, power losses and efficiency are determined depending on battery state of charge (SOC) and operating power. For electrochemical transient modelling, an equivalent RC-circuit is included based on Thevenin battery model. It is assumed in the model that internal resistance, open circuit voltage and the RC-circuit voltage drop depends only on the SOC. Experimental data was obtained from the LG INR18650 MJ1 battery discharge curves. Modelling was performed for SOC values in the range of 0.17 to 0.95 since the terminal voltage dependence on SOC is nearly linear there. The proposed model is sufficient for state of charge estimating and battery performance determination. (paper)