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Sanja Bajić

Društvene mreže:

R. Gaćina, Sanja Bajić, Bojan Dimitrijevic, T. Šubaranović, Čedomir Beljić, Dragoljub Bajić

Surface mining of coal has a negative impact on the environment that needs to be prevented, reduced, controlled, monitored by applying the management of technological processes of technical and biological recultivation after the end of exploitation works. The paper deals with the problem of multi-criteria decision-making in the process of selection of indicators that have an impact on the choice of purpose of recultivated terrain after the end of coal mining. The considered reclamation solutions represent possible alternatives. Degraded areas need to be returned to their original purpose, they should be in the function of environmental protection of the natural environment and settlements near this location. In addition, various criteria and sub-criteria that affect the choice of the most favourable solution were defined and analyzed. The final decision on land use after exploitation was made based on mathematical calculations using the multi-criteria VIKOR method.

Miodrag Čelebić, Dragoljub Bajić, Sanja Bajić, M. Bankovic, Duško Torbica, Aleksej Miloševič, Dejana Stevanović

The selection of the optimal equipment for discontinuous haulage systems is one of the most important decisions that need to be made when an open-pit mine is designed. There are a number of influencing factors, including natural (geological and environmental), technical, economic, and social. Some of them can be expressed numerically, in certain units of measure, while others are descriptive and can be stated by linguistic variables depending on the circumstances of the project. These factors are characterized by a high level of uncertainty, associated with both exploration and mining operations. The experience, knowledge, and expert judgment of engineers and specialists are of key importance for the management of mining processes, consistent with the issues stemming from the dynamic expansion of open-pit mines in space over time. This paper proposes an integrated model that translates all the criteria that affect the selection of the optimal solution into linguistic variables. By employing the multiple-criteria decision-making method and combining it with fuzzy logic, we developed an algorithm that addresses all the above-mentioned uncertainties inherent in various mining processes where the experience of experts forms the basis. The fuzzy analytic hierarchy process is used in order to deal with trending decision problems, such as mining equipment and management system selection. The entire algorithm was applied to a real case study—the Ugljevik East 1 open-pit mine.

Sanja Bajić, Dragoljub Bajić, Branko Gluščević, R. Gaćina, Josip I. Išek

When solving real problems, and to make a quality decision, it is necessary to consider a great number of often complex parameters. For these reasons, the development of decision-making process modeling has seen significant growth in recent years, and multi-criteria optimization models have stood out among them as useful for solving complex and conflicting phenomena. Multi-criteria optimization models make it easier for decision-makers to find the optimal solution in situations where there are many different criteria, which can often conflict with each other. The choice of the appropriate method of exploitation of mineral deposits follows the consideration of the problem and the approach to further development, which is primarily the determination of the criteria that influence the choice of the optimal alternative.

M. Stepanović, Dragoljub Bajić, Momčilo Blagojević, Sanja Bajić

As the global population grows, we are witnessing rapid urbanization and the development of industry and agriculture. Novel, largely toxic substances are being used in agriculture to improve yields. All of this has led to the generation of large amounts of pollutants that need to be disposed of and treated. Irresponsible behavior and discharges into nature and river channels not clearly defined by law or sanctioned, certainly have an environmental impact. The Drina River Basin occupies parts of the territories of four countries. It is one of the most important drainage areas in the West Balkans. It calls for international cooperation in many areas, such as public water supply, irrigation, hydropower generation, and the like. However, in order to achieve such cooperation, all the countries that “steward” the resource need to commit to water quality conservation and protection. The DPSIR approach proposed by the Water Framework Directive of the European Union is followed to identify major pressures (pollution sources) in the Serbian part of the Drina River Basin. The pressures are grouped into several categories and described in detail.

Miodrag Čelebić, Sanja Bajić, Dragoljub Bajić, Dejana Stevanović, Duško Torbica, V. Malbašić

Technoeconomic, environmental and safety criteria generally affect the management of metallic and non-metallic mining operations. The first basic question that needs to be addressed when planning ore mining is which methods are adequate and what is the optimal mining technology? Due to the complex geologic framework of ore deposits, geological exploration has rendered synonymous the inherent uncertainties, vagueness, and inaccuracies. As a result, subjective evaluation by engineers and expert experience have become increasingly important. Given that the natural language used by miners and geologists is most suited for relaying knowledge and expressing opinions, the paper tests a fuzzy optimization methodology that uses linguistic variables. Consequently, extent analysis is applied to fuzzy AHP by means of triangular fuzzy numbers to arrive at a decision about the optimal mining technology. The entire procedure constitutes an integrated mine management system, which will contribute to sustainable production in the future. A case study to which the model was applied is presented in the paper.

Sanja Bajić, Dragoljub Bajić, Branko Gluščević, Vesna Ristić Vakanjac

The selection of the most appropriate underground mining technology is not a simple process because it involves handling of a large amount of information about several potential methods. Multicriteria optimization approaches are proven useful tools for ranking alternatives, especially in cases where multiple complex criteria have to be considered simultaneously. An ore deposit is a complex system because of its geology, physical and mechanical properties, and hydrogeological conditions. As such, problem solving requires a heuristic approach and includes tasks involving expert judgement, intuition, estimation, and experience. Using a heuristic strategy to state a problem means that the analyst is placed in a position to apply past experience to a future situation and existing knowledge to new circumstances, as well as discover new avenues to creative problem solving. A complex algorithm was developed to pave the way to quality management of mining, by using the VIKOR method to rank various mining technologies relative to a set of criteria and select the optimum mining method that will primarily ensure profitable and safe mining.

Levan Pavlenishvili, M. Anjos, Sanja Bajić, L. Lenoir

This paper explores the use of microgrids during cold-load pickup (CLPU) phenomena, which are typical after an outage in distribution networks with high share of ther-mostatically controlled load (TCL). We present a mixed-integer linear programming (MILP) formulation for scheduling service restoration (SR). The proposed model computes the optimal re-connection sequence, generation and storage levels for the microgrids as well as power supply level from the main grid. The model is tested on different modifications of the IEEE-13 feeder network. The proposed approach is suitable for practical SR scheduling and to test the CLPU capabilities of a distribution network during the planning process.

Bruno Fazio, Sanja Bajić, S. St.-Antoine

The arrival of modern protection relays on distribution networks offers us an excellent opportunity to better understand the performance of network protection and to efficiently identify coordination problems. The analysis of relay event reports helps establishing the source of unnecessary relay protection tripping. In this work, the analysis of measurements of digital over-current relays is conducted. The case study is focused on performing a macro level analysis of protection coordination on Hydro-Québec's distribution network. Additionally, a characterisation of short circuits has been performed. A list of observations followed by recommendations for improvement of relay protection strategy in distribution networks is presented using the results of this case study.

Slobodan Trajković, B. Nikolić, Ž. Kamberović, Sanja Bajić

After the migration of Serbs in 1690 and 1735, the exploitation of mines in the area of present-day Serbia ceased, and after a standstill of nearly 200 years, the mining and metallurgical activities in Serbia were activated in the second quarter of the 20th century. The first concessions were bought by England in 1926, then the mines in Stari Trg (1927), Kišnica (1927), Ajvalija (1930), Novo Brdo (1933) were activated, and the Flotation (1930) and Smelter with Lead Refinery began to operate (1939) in Zvečan. In Kosovska Mitrovica, the chemical industry began operating in 1961, the Zinc Metallurgy and Lead Battery Factory in 1967, and all production facilities were expanded and modernized several times. The most intensive production and investment period of the "Trepča" Combine was in the period 1965-1985, when "Trepča" was a well-known producer of lead, zinc, silver, gold, cadmium, bismuth and products made of these metals. After 1990, the production declined for several reasons and, in 1999, the international army stopped production in "Trepča". In the past twenty years, the production has not been completely renewed nor the status of the "Trepča" Combine has not been regulated.

Sanja Bajić, Dragoljub Bajić, Branko Gluščević, V. R. Vakanjac

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.

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