Bio-based composites are increasingly used. One of the most frequently used materials is hemp shives, which is agricultural waste. However, as the quantities of this material are lacking, there is a tendency towards finding new and more available materials. Corncob and sawdust are bio by-products that have great potential as insulation materials. In order to use these aggregates, it is necessary to examine their characteristics. New composite materials based on sawdust, corncobs, styrofoam granules, and the mixture of lime and gypsum as the binder were tested in this research. This paper presents the properties of these composites obtained by determining the porosity of samples, volume mass, water absorption, airflow resistance and heat flux, which was followed by the calculation of the thermal conductivity coefficient. Three of the new biocomposite materials, whose samples were 1–5 cm thick for each type of mixture, were investigated. The aim of this research was to analyze the results of different mixtures and sample thicknesses in order to determine the optimum composite material of the proper thickness so that the best possible thermal and sound insulation could be obtained. Based on the conducted analyses, the biocomposite with a thickness of 5 cm, composed of ground corncobs, styrofoam, lime, and gypsum, proved to be the best in terms of thermal and sound insulation. New composite materials can be used as an alternative to conventional materials.

Na primeru izgradnje jedne pristupne saobraćajnice prikazan je izbor optimalne vearijante gradjevinske mehanizacije za izvođenje zemlljanih radova. Izbor imedju mogućih varijanti je izvršem metodom višekriterijumske optimizavije Promethee. Vrednovanje varijanti je izvršeno preko više kriterijuma (broj mašina, cena, vreme, rezerva mašina, praktični učinak, broj radnika, cena efektivnog radnog sata.), pri čemu je razmatran uticaj svakog kriterijuma na konačno rangiranje alternativa. Upoređivanjem dva scenarija (sa različitim relativnim težinama kriterijuma) u modelu višekriterijumske optimizacije određeno je optimalno rešenje.U radu su izneti zaključci o uticaju pojedinih kriterijuma na konačno rangiranje alternativa.

The constant need for heat exchangers that are easy to manufacture and maintain, and that have a standardized and already known manufacturing technology, has led to the fact that shell and tube heat exchangers are one of the most common devices used in the process industry. In this paper, the analytical and numerical models of the basic shell and heat exchanger have presented with dimensions of 3750 x 1000 mm and a nominal heat capacity of 410 kW. Using the flow simulation, the influence of different numbers and arrangement of baffles and the changing the position of the inlet and outlet of warmer fluid are considered. The temperatures of the fluids on the inlet and outlet are taken into account as the main parameters for heat exchanger performance. From obtained results, it can be concluded that with the increase in the number of baffles, the performance of the heat exchanger is increased. The position of the inlet and outlet of the warmer fluid greatly influence the heat exchanger performance.

Motor vehicle speed is one of the inputs used to develop models for predicting road traffic noise levels. In existing models, the vehicle speed used as input to estimate the noise level is not the current (measured) speed, but the vehicle speed determined based on the speed limit by road type or vehicle type. Therefore, the development of a device for measuring vehicle speed using radar that works on the principle of Doppler effect, which is presented in the paper. The advantage of this measuring device is the low price compared to similar devices, easy use and the possibility of easy processing of data obtained by measurement. The device allows measuring speed in all weather conditions in terms of temperature, precipitation and time of day. Then, in real time, it displays the speed and direction of movement of the vehicle on the screen of the mobile phone, and in the stationary laboratory, remote control, adjustment and adjustment of the software for measuring speed is enabled.