The article outlines how to use the convergence of collections to determine the position of a mobile device based on the WiFi radio signal strength with the use of fuzzy sets. The main aim is the development of the method for indoor position determination based on existing WiFi network infrastructure indoors. The approach is based on the WiFi radio infrastructure existing inside the buildings and requires operating mobile devices such as smartphones or tablets. An SQL database engine is also necessary as a widespread data interface. The SQL approach is not limited to the determination of the position but also to the creation of maps in which the system dening the position of the mobile device will operate. In addition, implementation issues are presented along with the distribution of the burden of performing calculations and the benets of such an approach for determining the location. The authors describe how to decompose the task of determining the position in a client-server architecture.

The article discusses the monitoring of horizontal displacements of the channel of Dniester, the second largest river in Ukraine, based on topographic maps, satellite images, as well as geological, soil and quaternary sediment maps. Data pro-cessing has been carried out using the geographic information system ArcGIS. The monitoring over a 140-year period (1874–2015) has been performed at the river’s transition from a mountainous to plain terrain on the 67 km section of the river. During this period, maximum displacements in the study area were 590–620 m. The research examines water protection zones needed for channel displacements. The article describes the monitoring methodology and analyses changes over a pe-riod of 18 years (2000–2018). The analysis includes the anthropogenic influence on the channel in the monitoring area. Results of the research may be useful for construction and cadastral works related to the channel in the area concerned, as well as for water management.

Small-signal transmittances of the power stage of a flyback converter in continuous conduction mode are derived on the averaged model obtained by the separation of variables approach. The precise knowledge of these transmittances is necessary in the design process of the converter control circuit. Apart from mathematical formulas for transmittances, the numerical calculations of the frequency dependencies of the transmittances for the assumed set of the converter parameters are presented with the parasitic resistances of components taken into account. The results of the calculations are compared with the measurements performed on the laboratory model of the converter and a good consistency is observed. It is concluded, that the results of the paper may be useful in the designing process of a control circuit of the flyback converter.