Primjenjivost kontinuiranog monitoring sustava u realnom vremenu za održavanje sigurnosti važnih objekata

In recent years, there has been significant advancement in monitoring sciences, especially due to the continued development of measuring equipment. Consequently, continuous real-time monitoring of integrity of significant structures, like buildings, bridges, dams, as well as the movement of slopes, landslides and volcanoes has become possible. This paper presents the usefulness of continuous real-time monitoring system that is able to combine geodetic, geotechnical and meteorological sensors to match the needs of the monitoring project. At the experimental polygon, we have installed four points; one reference and three observation points, all based on global navigation satellite system (GNSS) sensors. For every point, we acquire location in sense of coordinate Y, X and H in the local coordinate system, which allows observing any movements and deformations on observation points. Moreover, the characteristics of experimental polygon correspond to observing structures and also any changes on the Earth’s surface. The real-time visualization of acquired data enables us to decide on further measures in the shortest possible time, which reflects in major safety, as well as in the avoidance of severe damage. On the basis of 20 minutes of measurements, executed every 24 hours, we have calculated that it is possible to detect, with a 99.73% probability, all displacements larger than 1.2 mm and relative movements larger than 3 mm. The monitoring results and regression lines indicate that displacements for two points are no more than 1 mm, while on one we have obtained displacement of approximately 7 mm in a time period of only three months. The results obtained are significant and confirm the necessity of continuous real-time monitoring systems.U posljednjih nekoliko godina, došlo je do velikog napretka u znanosti o nadzoru (monitoringu), posebice zbog kontinuiranog razvoja mjerne opreme. Prema tome, kontinuirani real-time nadzor integriteta značajnih objekata, kao što su zgrade, mostovi, brane, pomicanje padina, klizišta i vulkana, postao je moguć. Ovaj rad opisuje korist kontinuiranog monitoring sustava u realnom vremenu koji omogućava kombiniranje geodetskih, geotehničkih i meteoroloških senzora kako bi se odgovorilo potrebama monitoringa. Na eksperimentalnom poligonu su instalirana četiri mjerna mjesta; jedna referentna i tri promatrane točke, a sve se zasniva na globalnom navigacijskom satelitskom sustavu (GNSS). Za svaku točku može se odrediti položaj u lokalnom koordinatnom (Y, X, H) sustavu koji omogućuje praćenje pomicanja i deformacija na mjernim mjestima. Štoviše, karakteristike eksperimentalnog poligona odgovaraju opažanim strukturama kao i bilo kakvim promjenama na površini Zemlje. Real-time vizualizaciju prikupljenih podataka omogućuje odlučivanje o daljnjim mjerama u najkraćem mogućem roku, što se odražava boljom zaštitom radi sigurnosti, kao i izbjegavanjem ozbiljnih šteta. Na temelju 20 minutnih mjerenja, koje se vrši 24 sata na dan, izračunato je da je moguće s 99,73 % vjerojatnosti otkriti sva pomicanja veća od 1,2 mm, a relativna pomicanja veća od 3 mm. Rezultati monitoringa i regresijska analiza pokazuju da pomicanja dvaju mjernih mjesta nisu veća od 1 mm, a za jedno mjesto je dobiven pomak od oko 7 mm u vremenskom periodu od samo tri mjeseca. Dobiveni rezultati su značajni i potvrđuju nužnost kontinuiranih real- time monitoring sustava

Modelling of AT rockbolts parameters for "Soko" underground coal mine

U ovom radu je prikazan razvoj numeričkog modela interakcije stijenskog masiva i AT viseće podgrade u rudniku mrkog uglja "Soko", a izvršena je i usporedba rezultata dobivenih modeliranjem s rezultatima koji su dobiveni eksperimentalnim putem. Numeričko modeliranje je urađeno metodom konačnih elemenata, uporabom programa Phase2. Usporedba je pokazala da dobiveni rezultati potpuno korespondiraju, što potvrđuje ispravnost uvođenja predloženog sustava podgrađivanja u rudniku "Soko".Research in this article presents development of numerical model of strata interaction with AT (Advanced Technology) roof support in "Soko" deep coal mine and comparison of modelling parameters with results obtained through experimental measurements. Numerical model is based on finite elements method, using Phase2 software. Comparison showed almost complete concurrence, thus justifying introduction of suggested roadway supporting system into the "Soko" underground coal mine

Development of a new system of solid ionic conductors based on multi-doped ceria for application in IT-SOFCs

Nanosized multi-doped ceria with composition Ce0.8Nd0.0025Sm0.0025Gd0.005Dy0.095Y0.095O2-δ (CNSGDY) as perspective solid ionic conductor was obtained by modified glycine-nitrate procedure (MGNP) and room temperature self-propagating reaction (SPRT). The pressed pellets of both powders were sintered at 1550°C for 2 h in an air atmosphere. The obtained sintered samples were characterized by XRPD, Raman spectroscopy, FESEM, EDS and EIS methods. Despite a high temperature of sintering, XRPD and FESEM analyses of the samples confirmed appropriate dimensions of grains with fluorite structure. Overall concentration of introduced dopants (x = 0.2) in the structure of CeO2 after the sintering process was confirmed by EDS analysis. After sintering, Raman spectroscopy confirmed retention of the oxygen vacancies in the ceria lattice, which is in accordance with the improvement of ionic conductivity of solid ionic conductors. The highest value of total conductivity was obtained for the sintered MGNP sample at 700°C (4.22 × 10−2 S cm−1), with the corresponding activation energy of 0.26 eV

Mineralogical Characterization of the Grot Lead and Zinc Mine Tailings from Aspects of Their Further Use as Raw Material

The possibility of using waste tailings produced by flotation in the lead and zinc mine of Grot, Serbia as a potential source of secondary mineral raw materials was examined. The aim of the research was primarily to carry out a detailed characterization in order to determine the dominant minerals, and, for the first time, to trace the changes occurring in the unit cells of the minerals present in that deposit. There was also a need to determine the exact proportions of the present mineral phases for their further application and utilization as natural resources in environmental protection. Samples were taken from three different sections of tailings: the crest of dam (JKB), outlet pipe of the flotation facility (JOF) and hydrocyclone overflow (JHC). Granulometric separation was performed to facilitate the extraction of certain minerals from waste. The results showed that all samples mainly contained quartz, clinochlore, calcite, albite, pyrite and biotite, but their ratios in each sample varied significantly. After characterization, samples were separated into different fractions and their mineralogical compositions were determined. Depending on the fraction, the mineralogical compositions also changed. Mineralogy and geochemical analysis indicate that waste tailings can be used as a secondary mineral raw materials source applicable in various industries

Application of Lignite Combustion Waste Slag Generated in Heating Plants as a Partial Replacement for Cement. Part II: Physical–Mechanical and Physical–Chemical Characterization of Mortar and Concrete

The presented study is a continuation of the research with the aim of finding a useful value of hazardous waste slag generated by the combustion of lignite in heating plants and its application in the construction industry. The different amounts of cement (10%, 15%, 20% and 25%) were replaced with waste slag and silica fumes in mortars and concrete production. Detailed physical–mechanical characterization was performed on the mortar and concrete samples according to standard procedures. Test results indicated that the replacement of cement with slag and silica fumes reduces the physical and mechanical properties of mortar and concrete, but cement composites retained the required structural properties. If 15–20% is considered an acceptable level of compressive strength decrease, then it can be concluded that waste slag can be implemented in practice and be used as a construction material, with cement replacement in the maximal amount of 20% (17.8% of slag and 2.2% of silica fumes). On hardened mortar samples with maximal possible cement replacement (20%), physical–chemical characterizations were performed and included X-ray and infrared spectrophotometry, scanning electron microscopy, and thermal analysis. Results showed the absence of new phases and the presence of only those which were characteristic for starting samples, predominantly portlandite, quartz, calcite and calcium silicate-oxid

Hydrothermal Synthesized and Alkaline Activated Carbons Prepared from Glucose and Fructose—Detailed Characterization and Testing in Heavy Metals and Methylene Blue Removal

In the presented paper, activated carbons were prepared from fructose and glucose, and activating agents (KOH, NaOH, LiOH) by hydrothermal treatment (HTC) treatment. After preparation, samples were characterized in details. Different techniques were used: x-ray powder diffraction analysis, Raman spectral analysis, elemental analysis, and determination of textural and morphological properties. Obtained results showed dependence of investigated properties and the nature of precursors (glucose or fructose) as well as the type of hydroxides used as activating agents. After characterization, samples were tested as materials for heavy metals (Pb2+, Cd2+and Zn2+) and methylene blue removal. Also, adsorption experiments were performed on wastewaters taken from tailings of the lead and zinc mine and kinetic of the methylene blue removal was studied. The factors which distinguished the KOH activated samples were high yield (~14%), content of organic carbon (63–74%), porosity and specific surface area (SBET~700–1360 m2/g), a low degree of the crystal phase, indications that potassium ions may be included in heavy metals removal, good removal of the heavy metal ions (~47–59 mg/g for Pb2+, ~21–27 mg/g for Cd2+and ~6–10 mg/g for Zn2+) and fast (~10–30 min) and good methylene blue (~60–200 mg/g) removal

Ekonomické aspekty údržby pomocné mechanizace

The maintenance of auxiliary mechanization, in respect of dynamics and content of conducting procedures of preventive maintenance, should be very carefully apportioned and strictly adjusted to the real needs, because, in the contrary, some opposite effects may appear and significantly reduce reliability and effectiveness of auxiliary mechanization, with a considerable increase in expenses. Maintenance models are based on reliability parameters and optimization criteria of, most frequently, minimal costs and maximal readiness or are based on their compromises. Operation costs are in direct dependency on the selection of equipment for concrete conditions in open-pit working environment and engaged equipment production capacity. The economic demands assume that, while constructing and exploitation of the machine, the amount of the used material should be as little as possible, as well as that of work and time in relation to the unit of product, i.e. production during the exploitation period of the machine in service. This paper presents software for controlling the efficiency parameters of auxiliary mechanization at lignite Openpits in Serbia, i.e. the part which controls economic aspects and costs of maintenance. This software is developed to process data from three largest open-pits in Serbia: Kolubara, Kostolac and Kosovo. The software is tested in practice at big open pit and can be used in design of future open pits.Údržba pomocné mechanizace, v závislosti na rychlosti a objemu pochodů preventivní údržby, by měla být velmi pečlivě plánována a jasně upravována vzhledem k reálným požadavkům. V opačném případě může dojít k značnému poklesu spolehlivosti a efektivnosti zmíněné mechanizace se značným růstem nákladů. Modely údržby jsou založeny na spolehlivých hodnověrných parametrech a optimalizačních kritériích, především na minimálních nákladech a maximální rychlosti aplikace, popřípadě na jejich kompromisech. Provozní náklady jsou přímo úměrné výběru zařízení pro konkrétní podmínky v pracovním prostředí povrchových dolů a výkonnosti těchto používaných strojů. Z pohledu ekonomických požadavků je jasné, že v době rekonstrukce a exploatace stroje musí být objem používaného materiálu co nejmenší, a taktéž objem práce a času v závislosti na jednotce produktu, tj. poměr mezi dobou exploatace (objemovým výkonem) a servisní dobou. Článek presentuje a popisuje software pro kontrolu výkonnostních parametrů pomocné mechanizace na povrchových lignitových dolech v Srbsku, jako prvek hlídající ekonomické aspekty a náklady údržby. Software je vytvořen pro zpracovávání dat ze tří největších povrchových dolů v Srbsku: Kolubara, Kostolac a Kosovo. Software je testován v praxi na velkých povrchových dolech a může být použit při navrhování nových povrchových dolů

Model for the selection of the optimal location of a thermal power unit according to the external coal conveyance criterion

Aggravated working conditions in Serbian underground coal mines, and increasingly worse natural conditions (increased depthsof deposits, expressed tectonics, large inflows of underground waters etc.) resulted in higher exploitation costs which areat the threshold of profitability. This inevitably leads to the conclusion that it is necessary to link mines to thermal power plantsand facilities. The Soko and Lubnica mines can operate cost-effectively if they ground their production on the needs of a thermal powerheatingplant (TETO) which would supply the towns of Bor and Zaječar with the power. This paper deals with finding an optimallocation of a TETO using model for the optimal external coal conveyance from a mine to a thermal power unit

Mining and Metallurgical Waste as Potential Secondary Sources of Metals—A Case Study for the West Balkan Region

The aim of this paper is to present a chemical composition and quantities of mining and processing waste landfills material developed during historical mining and smelting. After detailed inspection, it was found that approximately 2.6 gigatons of the waste had been deposited at 1650 sites, covering almost 65 km2. More than half of this material, 55%, is characterized as conventional mining waste, 37% belongs to the processing tailings, and 8% to metallurgical waste. Most of these tailing sites are unclaimed, presenting a source of contamination for nearby communities. According to the literature data collected and additional chemical analyses, in accordance with zero-waste philosophy, about 42 promising locations (c. 270 million tons) could be selected, where various advanced eco-innovative methods of recovery could possibly apply. The areas with the highest prospective recovery are Serbia and Kosovo. In accordance with the metal prices achieved in March 2022, it is estimated that the recovery of tailings could bring up to 18,100 million USD, which is much more compared to the prices of March 2020—10,600 million USD—when the commodity market was governed by the COVID-19 restrictions. In addition to the commercial value of the metals, the environmental aspect should not be forgotten after the application of reuse and recycling concepts