Technical Faculty in Bor
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Naphtalene screening in Bor’s municipality based on its concentrations in leaves and stems of Hedera helix L.
(University of Belgrade, Technical Faculty in Bor, 2024) Papludis, Aleksandra; Alagić, Slađana; Milić, Snežana; Nikolić, Jelena; Zlatanović, Ivana; Snežana Jevtović; Stankov Jovanovic, Vesna
Naphthalene (Nap) belongs to the group of polycyclic aromatic hydrocarbons, and is considered as the simplest compound (it consists of two benzene rings). The aim of this work was to determine the content of Nap in the unwashed leaves and stems of poison ivy (PI). The samples were collected from nine locations in the area of Bor municipality, situated at different distances from the main source of pollution, i.e. from the metallurgical complex in the city of Bor, containing also the city heating plant. The highest concentration of Nap was found in stems of PI at the site S (66.63 μg/kg), while in the leaves was at site BN (45.89 μg/kg). Obtained results for the concentration of Nap in PI samples from each location were processed using factor R. Based on the calculated values for factor R, it can be concluded that at the sites FJ (2.05) and BN (1.39) closest to the metallurgical complex, and at rural sites SN (1.28), and O (1.70), the pollution of atmospheric origin was the greatest; also, it can be supposed that the proximity of the city heating plant and smelter was responsible for the increased R values (R1) at the sites from the urban/industrial zone, while increased R values in the rural zone were the result of domestic heating. In both zones, the traffic was also one of the possible sources of Nap. There is a possibility that plants absorbed Nap not only from the atmosphere but also from the soil.
Ranking of the most important criteria for the selection of the mining method for non-stratified deposits
(University of Belgrade, Faculty of Mining and Geology, 2024) Bogdanović, Dejan; Dehghani, Hesam; Saki, Farshad; Miletic, Slavica
Selecting and planning of the mining method for non-stratified deposits is the most delicate and complex process on which the success of the mine depends. This procedure is basically a multi-criteria decision making problem in which the aim is to select the best mining method from many alternatives. The aim of this paper is to show the influence of many factors (criteria) in the selecting of the most suitable mining method and to determine their influence on this process. The eight groups of influencing factors, i.e. criteria, were taken into account – geometric data on the ore body, the mechanical characteristics of the massif, the ore reserves, the situation on the surface of the terrain, the workforce, the possible environmental hazards, the market conditions and the safe working conditions. The AHP method was used for ranking these criteria. The ranking was carried out by mining experts and managers of various underground mines in Serbia using the group decision method. The results obtained show a clear distinction between the individual criteria when selecting the best mining method. Furthermore, the results clearly show the importance of the ranking process in determining the most influential criteria in this very complex process.
Behavior Analysis of the New PSO-CGSA Algorithm in Solving the Combined Economic Emission Dispatch Using Non-parametric Tests
(Taylor & Francis Group, United Kingdom, 2024) Gajić, Milena; Arsić, Sanela; Radosavljević, Jordan; Jevtić, Miroljub; Perović, Bojan; Klimenta, Dardan; Milovanović, Miloš
This paper proposes a new metahaeuristic algorithm named particle swarm optimization and chaotic gravitational search algorithm (PSO-CGSA) for solving the combined economic and emission dispatch (CEED) problem. First, we determine the efficiency and effectiveness measures of the algorithm and compare it with other well-known algorithms. Then, we analyze the obtained solutions using the statistical procedure proposed in the paper. The proposed procedure contains the following: (i) the behavior analysis of the algorithms when solving the CEED problem, using non-parametric tests, and (ii) the ranking of the algorithms using the PROMETHEE/GAIA multi-criteria decisionmaking method. The behavior analysis is performed for two cases: (i) when solving individual variants of the CEED problem (single-problem analysis) and (ii) when solving a set of CEED variants (multiple-problem analysis). The results of the applied procedure for the test system with six generators show that PSO-CGSA has (i) the best solution for each tested variant of the CEED problem; (ii) the best standard deviation, mean value, error rate, and behavior for the CEED variant with a bi-objective function that simultaneously minimizes fuel cost and emission, taking into account the valve point effect; and (iii) the best rank when solving a set of CEED variants.
The influence of aging parameters on thermal, mechanical and structural properties of the EN AW-6060 aluminum alloy
(Scientific Technical Union of Mechanical Engineering Industry-4.0, Bulgaria, 2024) Stamenković, Uroš; Marković, Ivana; Ćosović, Vladan; Markoli, Boštjan
This paper investigates the influence of aging parameters (temperature and time) on thermal, mechanical and structural properties of the EN AW-6060 aluminum alloy. Thermal diffusivity and hardness were measured after applied heat treatments followed by investigation on scanning electron and transmission electron microscopes. Heat treatments included: solutionizing at 550°C for 1 hour followed by quenching in ice water; after quenching samples were aged at two separate temperatures of 180°C and 200°C for 1-8 hours. The results show that hardness gradually increases with aging time achieving peak value of 95 HV10 after aging at 180°C for 5 hours. Thermal diffusivity also increases with both aging time and temperature achieving peak values after aging at 200°C for 4 hours. SEM/EDS analysis show the existence of finely distributed precipitates containing Mg, Si and Fe. TEM investigation confirms the existence of rod-shaped
precipitates several nanometers in length.
The influence of ageing parameters on microhardness, electrical conductivity and microstructure of some Al-Mg-Si alloys
(University of Belgrade, Technical faculty in Bor, 2024) Stamenković, Uroš; Marković, Ivana; Ćosović, Vladan; Markoli, Boštjan
This paper investigates the influence of ageing parameters (temperature and time) on the microhardness, electrical conductivity and structural properties of two Al-Mg-Si aluminium alloys. After the applied heat treatment, both microhardness and electrical conductivity were measured. Optical microscopy was used to investigate the microstructures after ageing. The heat treatment began by solutionizing the samples at 550°C for 1 hour, followed by quenching in ice water. Samples were then aged at two separate temperatures, 180°C and 200°C, for 1–8 hours. The results indicate that with the increase in ageing time, the microhardness gradually increases up to a maximum and then decreases, while the electrical conductivity continuously increases. Analysis on the optical microscope shows that with longer ageing, there is precipitation of a larger amount of the strengthening phases due to more intense diffusion of alloying elements from the solid solution.