Search

The structure of the military organization, its social, normative and legal role, doctrine, history and tradition, specific internal relations, combat readiness, weapons, external features, the attitude and behaviour of personnel to its fundamental values and, finally, the way it communicates with the public, make the totality of the identity of the Serbian Armed Forces. The way that the public perceives the identity characteristics of the military represents a dynamic category that we call an image. A reputation, like an image, is based on the subjective perception of an identity, with the difference that establishing a reputation requires personal experience in relation to the organization and the period in which such an experience is confirmed. Brand and branding are occasionally, theoretically inconsistently, related to the Serbian Armed Forces as an organization, while the main properties of these concepts established in marketing are ignored. This paper analyses various definitions and determinants of the concept of brand, and offers an answer to the question: whether and in which case it is possible to talk about "the brand of the Serbian Armed Forces" and why its public image should primarily be considered and studied through the prism of an organizational identity, image and reputation. The paper proposes that the organizational image and reputation of the Serbian Armed Forces be used as conceptual frameworks for considering its image in the public, while the concept of brand can be used in the sense of branding the Armed Forces as an employere.

Milan Uzelac, the author of this study, has written a broad insight into the problem of education itself with detailed and elaborated moments that constitute its social and historical aspects. What the author reaches is the real reflection of the state in today's educational system, and almost causes disappointment, but the feeling of hopelessness creates an insight into the meaning of the notion itself, from where the idea of being educated rises to the highest plane of observation.

As pressure equipment is most commonly used in various industrial fields, making manufacturing processes eco-friendlier (e.g., mass reduction of the final product, material and energy savings, etc.) and transitioning to sustainable production by developing eco-innovative products will have a positive effect on the environment. The aim of this paper is to analyze globe valve housing exposed to internal pressure using full-field experimental 3D digital image correlation (3D-DIC) method and numerical strain and stress data in order to propose improvements for more sustainable development, with respect to practical engineering application of EN standards. The highest von Mises strain values around 0.03% were measured on the point of highest geometrical discontinuity, sphere/cylinder intersection. Stresses of the examined globe valve using numerical and theoretical approach are significantly below material yield limit and allowable stress for internal pressure values of 30 bar, that is significantly higher than nominal operating pressure of 6 bar, proving that structure is over-dimensioned and can be optimized. New experimental procedure development and application in full-field strain analysis contributes to increased valve housing reliability, mass reduction and material and energy savings during manufacturing which directly affects its eco-friendliness, lowers manufacturing price and increases market competitiveness.

One of the biggest problems of environmental protection in Serbia is landfills. It is often a case that the economic interests are predominant in the landfill sitting, thus, most landfills are not located according to standards. This study shows that detailed geological data assets combined with geographical modeling represents a reliable way to define and locate the landfill site. Geological evaluation is discussed in detail with regard to bedrock lithology, quaternary geology, geological structure, hydrogeology, surface runoff patterns, and topography. An approach combining geographical modeling and geology is presented for determining the sites suitable for landfill selection with respect to their geologic favorability. As opposed to numerous research papers on this topic, in the methodological procedure, special importance is devoted to the analysis of the geological criteria. In this way, it is significantly easier to determine the landfill area with the best characteristics due to geological structure and lithology which unequivocally and precisely indicates inadequate territories for candidate sites. The multicriteria decision analysis (MCDA) is based on geological criteria upgraded with road (primary, residential, secondary, and tertiary), settlements network, railway, airport, infrastructure, land use, hypsometry aquifer, wetland, and surface water. The score values are divided into four classes, i.e., restricted areas, suitable but avoid, suitable, and most suitable. Combining geographical modeling with geology led to the recognition of two locations to be most favorable for landfill site located in the most suitable area, which represents 25.3% of the study area.

This study aimed to evaluate, in vitro, the antioxidative potential of fruit wines produced from berry fruits (i.e., black chokeberry, blueberry, blackberry, and raspberry), cherry, and apple by different technological processes. For this purpose, the activities of antioxidant enzymes (catalase, glutathione peroxidase (GPx), and superoxide dismutase (SOD)) and malondialdehyde (MDA) content as a marker of membrane damage were determined in wine-treated synaptosomes with hydrogen peroxide-induced oxidative stress. All studied wines induced increased antioxidant enzyme activities and decreased MDA levels compared to hydrogen peroxide-treated synaptosomes (i.e., control). The highest SOD activity was observed in synaptosomes treated with blackberry wine (6.81 U/mg), whereas blueberry wine induced the highest catalase and glutathione peroxidase activities (0.058 U/mg and 0.017 U/mg, respectively). Black chokeberry proved to be the best in lipid peroxidation protection with the lowest MDA value (1.42 nmol/mg). Finally, principal component analysis and hierarchical cluster analysis additionally highlighted a higher antioxidant capacity of wines produced from dark-skinned fruits (i.e., blackberry, black chokeberry, and blueberry). The results suggest protective effects of the fruit wines against oxidative damage, and, accordingly, their promising application as functional food.

We live in a period when smart devices gather a large amount of data from a variety of sensors and it is often the case that decisions are taken based on them in a more or less autonomous manner. Still, many of the inputs do not prove to be essential in the decision-making process; hence, it is of utmost importance to find the means of eliminating the noise and concentrating on the most influential attributes. In this sense, we put forward a method based on the swarm intelligence paradigm for extracting the most important features from several datasets. The thematic of this paper is a novel implementation of an algorithm from the swarm intelligence branch of the machine learning domain for improving feature selection. The combination of machine learning with the metaheuristic approaches has recently created a new branch of artificial intelligence called learnheuristics. This approach benefits both from the capability of feature selection to find the solutions that most impact on accuracy and performance, as well as the well known characteristic of swarm intelligence algorithms to efficiently comb through a large search space of solutions. The latter is used as a wrapper method in feature selection and the improvements are significant. In this paper, a modified version of the salp swarm algorithm for feature selection is proposed. This solution is verified by 21 datasets with the classification model of K-nearest neighborhoods. Furthermore, the performance of the algorithm is compared to the best algorithms with the same test setup resulting in better number of features and classification accuracy for the proposed solution. Therefore, the proposed method tackles feature selection and demonstrates its success with many benchmark datasets.

In this paper, a multi-objective optimization of geothermal water desalination plant with ejector refrigeration system is proposed. The multi-objective antlion optimization algorithm is used. Six different optimization scenarios were performed with economic (total investment cost and profit) and thermodynamic (exergy destruction) objectives for refrigerants R11, R114 and R717. Multi-criteria decision making with integrated AHP and PROMETHEE II approach is executed for evaluating the most suitable design project and refrigerant. Besides economic and thermodynamic criteria, three additional environmental criteria were used: ozone depletion potential, global warming potential and toxicity. The sensitivity analysis showed that water desalination plant with R114 refrigerant and coefficient of performance 0.507 is optimal for a wide range of criteria weights. A similar result of the optimal design point is obtained in scenarios where only economic objective functions were considered during the optimization procedure. Furthermore, it is proved that R114 Pareto front is more optimal in comparison with other refrigerants.

alpha-Glucosidase inhibitory activity (AGL) of fruit wine samples made from blueberry, black chokeberry, blackberry, raspberry and sour cherry cultivars grown in Serbia was studied using an microvinification procedure. More precisely, both sugar and enzyme were added to the fruit must before fermentation for half of the samples. This increased the extraction of phenolic compounds. All the samples showed higher bioactivity compared to acarbose, the compound used as a positive control. Blueberry (IC50 similar to 27 +/- 1 mu g/ml) and black chokeberry (IC50 similar to 28 +/- 1 mu g/ml) wine samples had the highest values regardless of the vinification method. In addition to this, chlorogenic and caffeic acids were recognised as their key AGL bioactives. Taken all together, the fruit wine samples or their lyophilised extracts may be considered as complementary medicine supplements of potential interest for the control of postprandial hyperglycemia.

To ensure reliability of pressure vessels during service it is necessary to (1) know properties of materials used in their design and (2) evaluate vessels’ behaviour under different working conditions with satisfying accuracy. Due to various technical and/ or technological requirements, nozzles are usually welded on vessel’s shell producing geometrical discontinuities that reduce the safety factor. To evaluate their influence, vessels with two different nozzles were experimentally studied and critical areas for crack initiation have been identified by 3D Digital Image Correlation (DIC) method. After that, the numerical analysis of equivalent 3D finite element model was performed and obtained results were compared with experimental values. In the most critical area, next to the one of the nozzles, crack was initiated and then growth of the damage was simulated using extended finite element method (XFEM). In this paper evaluation of stress intensity factors (SIFs) along crack path is presented, as well as the most probable direction of the crack propagation on the shell. Based on SIFs values, critical length of the crack and number of pressure cycles to the final failure were estimated.

Different applications of a variable area convergent-divergent nozzle are found in various parts of the industry. This paper presents the development of a new design methodology for a variable area convergent-divergent nozzle, to maintain constant nozzle area ratio for different values of mass flow rates. The validation of the presented model was carried out on an example supersonic ejector using experimental, numerical and analytical data. Analytical (one dimensional) and computational fluid dynamics models showed satisfactory prediction performance in comparison with the experiment. The average entrainment ratio error was between 10% and 7%, respectively. Results confirmed that the velocity of the primary fluid at the nozzle outlet is in accordance with the one dimensional analysis. Although disturbances (strong and weak shock waves) are visible, their effects are negligible. Also, supersonic ejector performances are presented through relations between entrainment ratio, outlet pressure and spindle position. Disadvantages of variable area nozzle utilization in ejector applications are emphasized.

The article deals with the morphogenesis of the through cave Pećina na Reci Zamni (meaning in Serbian: Cave on the Zamna River; in further text: the Zamna Cave). The Zamna Cave was the subject of several geomorphological studies, mostly aimed at explaining the cave genesis through the evolutionary concept from through caves to natural bridges. In order to get better insight into the morphogenesis of this cave, modern geomorphometrical methods were applied. The cave and the surface topography above it were scanned in high resolution using the instrument Leica Nova MS50, applying the method of terrestrial laser scanning (TLS). Data processing produced the model for the analysis of the relation between surface and underground forms of karst relief. The results point to the conclusion that the Zamna Cave is an example showing that in the process of natural bridges formation by cave roof collapse, it is not necessary that there is a dry valley above the cave, as previously thought. Pećina na reci Zamni bila je do sada predmet više istraživanja. Neka od njih imala su za cilj objašnjenje geneze pećine u svetlu evolucije tunelskih pećina ka prerastima. U cilju boljeg razumevanja geneze ove pećine primenjene su savremene morfometrijske tehnike. Pećina i površina iznad nje snimljeni su u visokoj rezoluciji uređajem Leica Nova MS50, postupkom terestričkog laserskog skeniranja (TLS). Obradom prikupljenih podataka dobijen je model na kome je moguće analizirati odnos površinskih i podzemnih kraških oblika reljefa. Rezultati analize navode na zaključak da je pećina na reci Zamni primer koji ukazuje na to da prilikom formiranja prerasti urušavanjem tavanica pećina nije pravilo da se neposredno iznad pruža suva dolina.

Pressure equipment has widespread application in various industrial sectors. Due to this variety, pressure equipment can have complex structure and is subjected to different working loads (static, dynamic, thermal etc.) during the operation life that can cause failure. Strain measurement of complex structure has always been a huge challenge for researchers. Conventional experimental methods (e.g. strain gauges) give only limited data sets regarding measurement on critical areas with high geometrical discontinuities. 3D Digital Image Correlation method is an optical method that enables full-field strain measurement of critical areas on structural components. Sphere/cylinder junction is common geometrical discontinuity on pressure equipment and globe valve housing was chosen as representative example. In this paper, globe valve housing was subjected to external axial loading caused by pipeline dilatations. Highest measured von Mises strain values around 0.15 % were recorded on cylinder/sphere intersection. Determining strain state of critical areas enables better understanding of complex structures and provides an opportunity for further development and improvement for practical industrial application.

Swarm intelligence techniques have been created to respond to theoretical and practical global optimization problems. This paper puts forward an enhanced version of the firefly algorithm that corrects the acknowledged drawbacks of the original method, by an explicit exploration mechanism and a chaotic local search strategy. The resulting augmented approach was theoretically tested on two sets of bound-constrained benchmark functions from the CEC suites and practically validated for automatically selecting the optimal dropout rate for the regularization of deep neural networks. Despite their successful applications in a wide spectrum of different fields, one important problem that deep learning algorithms face is overfitting. The traditional way of preventing overfitting is to apply regularization, the first option in this sense is the choice of an adequate value for the dropout parameter. In order to demonstrate its ability in finding an optimal dropout rate, the boosted version of the firefly algorithm has been validated for the deep learning subfield of convolutional neural networks, with respect to five standard benchmark datasets for image processing: MNIST, Fashion-MNIST, Semeion, USPS and CIFAR-10. The performance of the proposed approach in both types of experiments was compared with other recent state-of-the-art methods. To prove that there are significant improvements in results, statistical tests were conducted. Based on the experimental data, it can be concluded that the proposed algorithm clearly outperforms other approaches.

The possibilities of testing real constructions are often limited, especially in case of large constructions. The idea of model testing is to create a sub-scaled model in order to anticipate the behavior of the real construction, regarding the behavior of the model, with sufficient accuracy. The aim of this paper is to demonstrate that model testing of bucket wheel excavator structure, from the aspect of the strength of the constructions, is possible. In order to prove this assumption, firstly, numerical calculations of a real construction and its sub-scaled model were performed using the Finite Element Method. Sub-scaled structure is 10 times scaled real structure (in size and plates thickness). Within the static calculation, the analysis of the stress mapping from sub-scaled model to real structure was carried out, by partial groups of construction. The coefficients connecting stresses of sub-scaled model and stresses of real construction were formulated. Dynamic calculations of sub-scaled model and real structure were also performed. Then, a physical model was produced and subjected to experimental testing. Experimental testing was performed in order to verify the numerical models. A parallel testing of the model with strain gauges and a system for non-contact measurement of displacement and deformation was performed. High matching results were obtained of two experimental methods on one side, and numerical calculation on the other side. The physical model and the successful experiments carried out on it confirmed that these structures can be subjected to model testing, without important constraints and with sufficient accuracy.

Protection and promotion of geoheritage has been changing and improving in recent decades, in line with the growing research in this field. Some research papers specifically study geomorphological geoheritage and introduce a special term − geomorphosite. Karst geomorphosites present specific objects of geomorphological heritage. On Kučaj and Beljanica mountains there is the largest karst area in Serbia. The purpose of this paper is to select and evaluate the scientific value of karst geomorphosites of Kučaj and Beljanica. More than one hundred karst geomorphosites were analyzed. In order to achieve more adequate coverage and representation, they were grouped into 25 geomorphotypes in three major geomorphological components of the investigated area. The results of this analysis highlighted the most important natural potentials of this area for establishing a karst-based geopark. More than 20 geomorphotypes have a positive recommendation index, which provides a good basis for further geotourism analysis.

In this study, we estimated the usage of Cabernet Sauvignon in microvinifications, obtaining wines with increased phenolic compound content. Kinetic extraction of phenolic compounds during alcoholic fermentation was affected by maceration time (3, 5, 7, 14 and 21 days) and the addition and kinetics of enzyme preparations (EP). The highest extraction rates were observed for catechin (EXV EP – EXV enzyme preparation and CP EP – Color plus enzyme preparation) and p-hydroxybenzoic acid (Car EP - Caractere enzyme preparation). According to extraction time of the analyzed phenolic compounds, maximal values (ellagic acid, ferulic acid, chlorogenic acid, caffeic acid, naringenin, p-hydroxybenzoic acid, p-coumaric acid, protocatechuic acid, trans-resveratrol, syringic acid, vanillin, and vanillic acid) were obtained on day 15 of maceration with addition of CP EP, with exceptions of gallic acid, catechin, and myricetin. Prolonged maceration times, up to 21 days, showed the most potent DPPH free radical scavenging activity with Car EP and the highest Ferric Reducing Ability of Plasma (FRAP) values with CP EP. Во ова истражување беше применета микровинификација на грозје од сортата каберне совињон и беа добиени вина со зголемена содржина на фенолни соединенија. Беше забележано дека кинетичката екстракција на фенолните соединенија во текот на алкохолната ферментација зависи од времето на мацерација (3, 5, 7, 14 и 21 ден) и од додавањето и кинетиката на ензимските препарати (EP). Најголема екстракција беше забележана за катехин (EXV EP – комерцијален ензимски препарат и CP EP – ензимски препарат) и p-хидроксибензоева киселина (Car EP – ензимски препарат Caractere). Во однос на влијанието на времето на екстракција врз анализираните фенолни соединенија (елагова киселина, ферулна киселина, хлорогенска киселина, кофеинска киселина, нарингенин, p-хидроксибензоева киселина, p-кумарна киселина, протокатехинска киселина, trans-ресвератрол, сирингинска киселина, ванилин и ванилна киселина), максимални вредности се добиени петнаесеттиот ден од мацерација со додавање на CP EP, со исклучок на гална киселина, катехин и мирицетин. Продолженото време на мацерација до 21 ден доведе до највисока антиоксидантна активност одредена со методите DPPH и FRAP, кај вината со Car EP и CP EP.

The main purpose of this research is to assess the outdoor thermal comfort (OTC) of Belgrade, in order to investigate how distinct bioclimatic conditions influence on the human organism during the summer in urban environments. Universal Thermal Climate Index, which represents the heat stress of the human organism caused by meteorological conditions, was used as an indicator of thermal comfort in the study. The main goal was to monitor changes in the index values, as well as the frequency of various categories of thermal stress during the hottest part of the year (months June, July, and August). For this research, mean daily meteorological data from the Meteorological Observatory Belgrade have been collected for the period from 1999 to 2018. The obtained results show a gradual change in the bioclimatic conditions, which are generally more adverse in July and August. Results also indicate that OTC in Belgrade was considerably reduced, especially in 2007, 2012, 2015, 2017, and 2018.

This paper describes and analysis thermal dilatation of L compensator which is very common is engineering experience. It was analyzed self-compensation of L compensator and it shown results obtained using methodology according standard AD 2000 and other engineering methods. The ref-erence length of the L compensator arms is 12 and 6m, which is compared with the results obtained. Pipe material is P235GH, dimensions DN300 (ф323.9х 7.1 mm).

Complex structure experimental analysis has always been a huge challenge for researchers. Conventional experimental methods (e.g., strain gauges) give only limited data sets regarding measurement on critical areas with high geometrical discontinuities. A 3D Digital Image Correlation method is an optical method that overcomes the limitations of conventional methods and enables full-field displacement and strain measurement of geometrically complex structures. System Aramis, based on Digital Image Correlation method, is used for experimental analysis and numerical model verification in this paper. Investigated complex structure is sphere/cylinder junction on globe valve housing subjected to axial loading. The highest experimentally measured von Mises strain values around 0.15% are recorded on cylinder/sphere intersection. Von Mises strain values on cylindrical and spherical part are several times smaller than on intersection itself. It is important to emphasize that, to the authors’ best knowledge, this is the first paper showing experimental results of 3D full and strain field of geometrically complex structure (sphere/cylinder intersection) on the intersection itself on pressure equipment. It is proven that 3D Digital Image Correlation method is fast and versatile method for recording strain during loading of complex structures. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR35031 and Grant no. TR35040]

Slaughter industry produces large amounts of waste water, which endanger and degrade the natural recipients - recipients, given that the waste vode najčešće discharged without any form of treatment or purification. Wastewater slaughter industry carry faeces, straw, unprocessed animal feed, various stomach secretions, blood, fat, a variety of solid waste and other organic matter present. Many applied technical and technological solutions in order to prevent harming the recipients are not given adequate results from the ecological aspect. The reconstruction of a system for pre-treatment and slaughter waste water by applying technological solutions ejector - pump, not only have obtained good results required by the project, but also pointed to the possibility of their use in many types of agro-industrial waste water, especially with the growing number of small agro-industrial drive .

Plum wines made from two cultivars of Prunus domestica L. (Požegača and Crvena ranka) and one cultivar of Prunus insititia L. (Trnovača) were evaluated for their total phenolic and anthocyanin contents. LC–MS/MS analysis based on specific MS transitions in the multiple reaction monitoring (MRM) mode was used for the identification and quantification of selected phenolic compounds. Catechin, chlorogenic and caffeic acids, as well as quercetin, were identified as the main polyphenols in plum wines. The total amount of phenolic compounds ranged from 1.24 to 1.58 g gallic acid equivalent per L. Among the examined wines, the Crvena ranka wine had a higher content of anthocyanins (12.31 mg cyanidin-3-glucoside equivalent per L). The antioxidant capacity of the wines was determined using the DPPH assay. The variations in the physicochemical characteristics, phenolic composition and DPPH radical scavenging activity of these wines are related to differences due to the different plum cultivars used in the preparation of each wine. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 172053]