The paper proposes a problem-solving approach in the area of underground mining, related to the evaluation and selection of the optimal mining method, employing fuzzy multiple-criteria optimization. The application of fuzzy logic to decision-making in multiple-criteria optimization is particularly useful in cases where not enough information is available about a given system, and where expert knowledge and experience are an important aspect. With a straightforward objective, multiple-criteria decision-making is used to rank various mining methods relative to a set of criteria and to select the optimal solution. The considered mining methods represent possible alternatives. In addition, various criteria and subcriteria that influence the selection of the best available solution are defined and analyzed. The final decision concerning the selection of the optimal mining method is made based on mathematical optimization calculations. The paper demonstrates the proposed approach as applied in a case study.

This paper describes how uncontrolled and illegal mining of sand and gravel can affect surface water and groundwater regimes in places where there is a hydraulic connection between them, based on a case study of the Velika Morava River in Serbia. Also, a change in cross-profile geometry, as a result of anthropogenic and natural factors, hinders the preparation of this river for inclusion among Serbia’s waterways. The Velika Morava River’s navigability would enable the development of waterborne transportation for both merchant ships and vessels of the Serbian Armed Forces River Flotilla. Correlations between water levels at gauging stations, as well as correlations between groundwater levels and river water levels at gauging stations, are used to show the dependence of these parameters on the change in the river bed profile after sand and gravel mining at the locations near gauging stations. In addition, the homogeneity of time-series of average annual elevations and the variance of the water levels of the Velika Morava River, measured in gauging stations during different periods, are statistically analyzed. The deepening of the Velika Morava riverbed where it was indiscriminately excavated in the 1980s led to the disruption of the groundwater regime and the hydraulic connection with the river, which lowered the water table of the aquifer used for the public water supply, as well as causing a number of other negative consequences.

The study focuses on validating reference methods such as ICP-OES and ICP-MS for detecting ultra-trace levels of chromium in groundwater, where concentrations are typically very low. Additionally, it verifies a hyphenated technique, IC-ICP-MS, for determining naturally occurring Cr(VI) in tested waters. The validation process involved various chromium analysis variants, including isotopes ⁵²Cr and ⁵³Cr in ICP-MS and IC-ICP-MS techniques, along with specific emission lines in the ICP-OES technique. Statistical data processing revealed that the achieved limits of quantification for Cr in different techniques ranged from 0.053 µg/L to 1.3 µg/L, with the associated measurement uncertainty estimated between 14% and 19% (at a coverage factor k = 2, 95%). For speciation analysis, it was possible to quantitatively determine Cr(VI) at concentrations as low as 0.12 µg/L, with the measurement uncertainty ranging between 10% and 14%. The Kruskal-Wallis test indicated that for the 14 water samples analysed, there was no statistically significant difference in the results obtained using different analytical techniques (p > 0.05). The geochemical modelling approach applied enhances the understanding of chromium speciation in water samples, verifying the accuracy of speciation analysis and identifying specific ion forms in which Cr(III) and Cr(VI) occur. In the analysed water samples, the concentration of Cr(VI) ranges between 0.13 and 35 µg/L, with the primary form identified as the oxoanion CrO₄²⁻. Importantly, statistical tests demonstrated no statistically significant differences between the total chromium concentration in water and the concentration of Cr(VI), indicating that the entire concentration of total chromium corresponds to Cr(VI) speciation.

In order to successfully steer a ship, a man, ship’s watch officer, or commander of the ship must be physically ready and must know the maneuvering characteristics of the ship he steers, as well as the forces acting on him. For that, it is necessary for him to know the specifics of the ship because each ship has its own "mood", its specific properties that depend on the type, and size of the ship. Therefore, maneuvering properties differ even in ships of the same type and therefore it is important to know the specifics of a particular ship. Also, the same ship will behave differently in different situations. When the ship finds itself in situations that require urgent reaction during the voyage, then the experience and skills of the ship's captain come to the fore. Then it is important that the captain, based on his experience, chooses the right maneuver, but also that he always has at least one reserve maneuver in his head. That decision in certain situations must be made in a very short period of time, and the future of the ship and human lives often depends on it, as well as the resources on board. Every skill is acquired through practice, and it is logical that the commander will react faster and more correctly in every new situation. Precisely because of this, the most intensive training is necessary for the formation of quality ship commanders. For that reason, the training of future ship commanders on ship simulators gives excellent results. On ship simulators, they can gain a lot of experience and go through countless scenarios. In this paper, the use-value of ship simulators from the aspect of the training was verified through the Search and Rescue (SAR) exercise realized on the ship simulator Wärtsilä Navigation Simulator NTPRO 5000. It has been shown that the simulator can successfully check and recognize the optimal SAR pattern, maneuvering characteristics of the ship, as well as practice, maneuvering the ship and resolving specific situations that ship commanders may encounter in real situations. Training on ship simulators cannot completely replace training in real situations, but it can be used to get acquainted with the maneuvering characteristics of the ship, train in working with navigation devices, and be a good starting point in preparing people who are trained to perform tasks in real situations. The use of hydrological data of relationships between different types of data using an autoregressive model (AR model) can contribute to the creation of more realistic scenarios on ship simulators. It is also possible to apply data in the modeling of the environment and connect them with the current hydrological situation of the waterway. In the exercise evaluation process, we can see if the ship's captain used the hydrological data in the right way.