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Ranking Open-pit Mines using TYpe-1 Criterion Interval Extension in EDAS++ as a Comparative MCDM Method
No full textDue to its wide application, multi-criteria decision-making has easily found its
way to the mining industry as well. Mining is particularly interesting from the
multi-criteria analysis aspect, as mining projects require analyzing numerous
factors affecting the exploitation process. However, multi-criteria problems
are among the poorly structured decision-making models, given they take place
in stochastic conditions. This primarily refers to the number of criteria and the
complexity of their mutual relationships, which can be characterized by a
complete contradiction, and the methodologically diverse space for
determining preferences or weight factors that significantly affect decisionmaking results. In this paper, the use of EDAS++, normalized matrix data
values, and interval criteria, presented through a mathematical model and
example, allows ranking in conditions where some of the criteria have an
optimal value interval of attributes that are equally relevant and therefore
invariant with respect to decision. EDAS++ was used as a comparative
method in analyzing open-pit limestone mines to obtain the broadest possible
range of ranking methods while working on a doctoral dissertation entitled
"Decision-making in case of different mining project solutions by comparative
single and multi-criteria modeling.
Statistical analysis of pollution indices in the last two decades for the Boka Kotorska bay, Adriatic Sea
No full textThe surface sediments sampled from forty sampling sites in the Boka Kotorska Bay, starting from October 2005 to December 2019, were analysed for the content of ten heavy metals (As, Cd, Cr, Cu, Hg, Mn, Ni, Pb, Zn, Fe). Five complex indices (pollution load index (PLI), potential ecological risk index (RI), mean ERM quotient (MERMQ), toxic risk index (TRI), contamination severity index (CSI)) were determined for each site in the study period (2005, 2007, 2013, 2019), and statistically examined by principal component analysis (PCA) and cluster analysis (CA). In the semi-enclosed Bay, which consists of four smaller bays (Kotor, Risan, Tivat, Herceg Novi bays), a spatio-temporal comparison of sediment quality was carried out using PCA and CA analysis of the considered pollution indices. Statistical results revealed that the increased environmental risk in 2005 was observed in the bay of Kotor; in 2007 was in the bay of Tivat and Risan; in 2013 in the bay of Kotor and Tivat; and in 2019 was in the bay of Tivat, particularly at the shipyard site Bijela. The PCA and CA analysis highlighted that the sediment contamination in Kotor bay decreased from 2005 to 2019, while at the same time increased in Tivat bay, which is an indication of pollution due to urbanization and population growth in this part of the Bay. The results gave a statistical overview of the similarities between the pollution indices and the differences in the degree of sediment pollution in the Bay during the last two decades
Determination of ductile-to-brittle transition temperature of NIOMOL 490K steel welded joints
No full textThis paper is devoted to the ductile–brittle transition behavior of high strength low
alloyed (HSLA) structural steel NIOMOL 490K. The steel is designed for welded pressure
vessels exposed to dynamic loads, operating at temperatures below zero, and that is why it must
have acceptable toughness. Due to its importance for the safety assessment of pressure vessels,
a characterization of this steel with Charpy V-notch test in range of temperature between-60 oC
and +60 oC was undertaken. Ductile-to-brittle transition curves were generated in the present
study by using instrumented Charpy machine and V-notch specimens; notches were located in
the parent material, heat-affected zone and weld metal. NDT-temperature and tensile properties
in temperature range from -60 oC to +60 oC are presented in this paper. We used different test
temperatures to better understand ductile-to brittle transition response than just use either
Charpy energy or other related ductility criteria
Wide Bandgap Perovskite Solar Cells with Enhanced Thermal Stability
No full textMetal halide perovskites have proven to be excellent semiconductors, with tuneable band gap, high absorption coefficients
and large charge diffusion length. Multi-component lead halide perovskite compositions are widely studied in order to
stabilize the perovskite phase, in particular for wide bandgap formulations. The vacuum-deposition of multi-component
perovskites is not straightforward, as the number of precursors is in principle limited by the number of thermal sources
available in the vacuum chamber. Here we present a process which allows to increase the complexity of the formulation of
vacuum-deposited lead halide perovskites films by multi-source deposition and pre-mixing both inorganic and organic
components. We apply it to the preparation of wide bandgap CsMAFA triple-cation perovskite solar cells, which are found to
be efficient but not thermally stable. With the aim of stabilizing the perovskite phase, we add guanidinium (GA+) to the
material formulation, and obtained CsMAFAGA quadruple-cation perovskite films with improved thermal stability, as
observed by X-ray diffraction and rationalized by microstructural analysis. The corresponding solar cells showed similar
performance with a remarkable thermal stability, when compared to the triple-cation perovskite devices. This work paves the
way towards the vacuum-processing of complex perovskite formulations, with important implications not only for
photovoltaics but also for other fields of application
Characterization of ground penetrating radar signal during simulated corrosion of concrete reinforcement
No full textIn this paper, the adequacy of the experimental design in the accelerated corrosion process with the impressed
current technique (IC) for ground penetrating radar (GPR) inspection was investigated. The aim of the study is to
observe how the GPR signal amplitude behaves under different distributions of corrosion products generated by
different exposure conditions in the IC technique. To investigate this, two different experimental setups were
prepared. The results are summarized, discussed, and supported by visual evidence, other non-destructive
techniques, and electromagnetic theory. The main finding is that the position of the sodium chloride solution
required to ensure accelerated corrosion of the reinforcement determines the behaviour of the GPR signal, as it
affects the position of the corrosion product layer and its distribution in the concrete cover
Anthropogenic and Climate Influence on Land Degradation
No full textBadlands are areas with scarce or completely absent vegetation formed in a wide range of lithologies in different climate conditions and exposed to a wide range of geomorphological processes [1]. Generally, rapid evolution governed by erosion processes is a consequence of complex mineralogical and physico-chemical sediment composition and climate conditions. Because of that, badlands are often described as natural field laboratories and, furthermore, badland material is suitable for laboratory experiments that can, in controlled conditions, provide insight of changes that occur in the field. As indicated above, beside lithology, climate is one of the most significant factors in badlands forming. Since human activities have great impact on the environment and since climate changes present one of the biggest environmental pollution problems nowadays, in this research badland material was exposed to different conditions with the aim of monitoring changes caused by extreme climate conditions and acid ice. Three samples from badlands in China organized in six sets were treated with ice (representing snow) and acid ice (frozen acid rain) during fifteen cycles, dried in the oven for three cycles and afterwards again threated with ice and acid ice for additional five cycles. After each cycle samples were photographed, so that physical changes can be tracked, while leachate was collected and analyzed for monitoring changes in its volume, pH, electrical conductivity (EC) and cation concentration. Beside slight oscillations in parameters through cycles of samples treated with acid ice, extreme changes in observed parameters were not noticed neither between samples, nor between treatments. Leachate EC were a bit higher in samples treated with ice, leachate volume was higher for samples treated with acid ice, while pH was similar in both cases. Cation concentrations are similar in the leachate of all tested samples. In most of cases, the highest concentrations were measured at the beginning of the experiment, during the first two cycles or during the first “ice” cycles after drying. This indicates the high cation concentrations originate from the sediment surface or washing along the crack that appeared after drying. Physical changes that occurred through cycles implied that heat/drought is more aggressive agent of sediment decay. Decay caused by ice is slower, not as aggressive as drought, but not negligible, causing noticeable and significant cracks and fissures of fragments. This experiment confirmed that drought has high impact on sediment weathering, but more importantly, pointed out the impact of ice and its thawing, opening new questions about climate impact on forming, erosion processes and evolution of badlands which need to be further examined
Laboratorijski razvijena metoda zasnovana na veštačkim neuronskim mrežama za predikciju svojstava cementnih veziva na bazi mehano-aktiviranog pirofilita
No full textVerifikacija tehničkog rešenja (Naučno-nastavno veće): Vinča, Institut za nuklearne nauke, Univerzitet u Beogradu, Institut od nacionalnog značaja za RS.
Korisnik/naručilac: Institut za tehnologiju nuklearnih i drugih mineralnih sirovina (Laboratorija za pripremu mineralnih sirovina), Beograd.
Napomena: TR je softversko rešenje koja zadovoljava kriterijum otvorenog izvora, umesto ugovora o prodaji, kao dokaz se prihvata opis tehničkog rešenja u časopisu adekvatne kategorije (M21a) (Pravilnik "Sl. glasnik RS", br 24/2016, 21/2017, 38/2017 i 159/2020).
godina izrade: 2020.
godina prihvatanja TR od strane: TR je verifikovano na MNO za Materijale i hemijske tehnologije 2021. god. (sednica MNO 29.11.2021, potvrda 13.12.2021
Non-Destructive Corrosion Inspection of Reinforced Concrete Using Ground-Penetrating Radar: A Review
No full textReduced maintenance costs of concrete structures can be ensured by efficient and comprehensive
condition assessment. Ground-penetrating radar (GPR) has been widely used in the
condition assessment of reinforced concrete structures and it provides completely non-destructive
results in real-time. It is mainly used for locating reinforcement and determining concrete cover
thickness. More recently, research has focused on the possibility of using GPR for reinforcement
corrosion assessment. In this paper, an overview of the application of GPR in corrosion assessment of
concrete is presented. A literature search and study selection methodology were used to identify the
relevant studies. First, the laboratory studies are shown. After that, the studies for the application
on real structures are presented. The results have shown that the laboratory studies have not fully
illuminated the influence of the corrosion process on the GPR signal. Also, no clear relationship was
reported between the results of the laboratory studies and the on-site inspection. Although the GPR
has a long history in the condition assessment of structures, it needs more laboratory investigations
to clarify the influence of the corrosion process on the GPR signal