Прегледај по Аутор "Jeremić, Dejan"

Сада се приказује 1 - 18 од 18
  • Сличица
    Ставка
    ANALIZA OSJETLJIVOSTI SNABDIJEVAČKIH LANACA DRVNIM PELETOM ZA REALNE USLOVE KOJI ODGOVARAJU BOSNI I HERCEGOVINI
    (Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2018) Vasković, Srđan; Radović, Zoran; Batinić, Krsto; Halilović, Velid; Gvero, Petar; Gajić, Anto; Mrkić, Maja Bosančić; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    Biomasa predstavlja značajan obnovljivi resurs. Posebno ako se njenom korišćenju prilazi sistematski i uz dobro planiranje. Drvna biomasa je najznačajniji predstavnik biomase koji se već uveliko koristi u proizvodnji peleta. S obzirom da je veliki broj mašina, postrojenja, ljudi i opreme uključen u proizvodni lanac peleta, potrebno je ustanoviti koji to faktori i koliko utiču na ovaj proces. Prije svega misli se na konačno formiranje cijene drvnog peleta i njegove zavisnosti od drugih energenata, cijena sirove biomase, transportnih distanci, cijene električne energije i slično. Ovaj rad je spojio proizvodni lanac peleta sa postrojenjem i distribucijom toplote u objekat preko odgovarajućeg matematičkog modela. Upravo smo u prošle dvije godine bili svjedoci nedostataka drvnog peleta i naglog porasta njegove cijene na tržištu. To svakako dodatno promoviše ovu problematiku i daje joj smisao za istraživanje. Postavlja se pitanje šta su realni uslovi pri kojima treba da dođe do povećanja cijena peleta na tržištu i za koliko? Odgovore na to daje ovaj rad.
  • Сличица
    Ставка
    ANALYTICAL SOLUTION FOR THERMAL VIBRATIONS OF SINGLE-LAYERED GRAPHENE SHEETS WITH VARIOUS BOUNDARY CONDITIONS
    (University POLITEHNICA Timisoara, 2018) Radić, Nebojša; Jeremić, Dejan
    This paper deals with analysis of thermal vibration behaviour of orthotropic single-layered nanoplate with various boundary conditions. The new first-order shear deformation theory is reformulated using nonlocal differential constitutive relation of Eringen. The governing equations of motion are derived from Hamilton's principle. Using Galerkin method, analytical solution for rectangular nanoplates under various boundary conditions are obtained. Numerical results are presented to show variations of the dimensionless frequency of single-layered nanoplates corresponding to various values of the nonlocal parameter and temperature change.
  • Сличица
    Ставка
    BUCKLING ANALYSIS OF ORTHOTROPIC DOUBLE- NANOPLATE- SYSTEMS BASED ON NONLOCAL TWO- VARIABLE REFINED PLATE THEORY
    (University Politehnica Timisoara, Faculty of Engineering Hunedoara, 2015) Radić, Nebojša; Jeremić, Dejan; Sekulić, Lana
    This paper presents an analytical study on the buckling of orthotropic double- nanoplate-system (DNPS) subjected to biaxial compression using the two-variable refined plate theory and nonlocal elasticity theory. The two - variable refined plate theory takes into account the effects of small scale and transverse shear strains through the thickness of the nanoplate. The theory assumes parabolic distribution of the transverse shear strains through thickness of the nanoplate and does not require shear correction factors. Derived nonlocal governing equations are based on the nonlocal theory and the principle of virtual displacements. The expression for buckling load of a simply supported orthotropic DNPS was derived using the Navier's method.
  • Сличица
    Ставка
    BUCKLING ANALYSIS OF SIMPLY SUPPORTED SQUARE SYMMETRIC LAMINATED COMPOSITE PLATE
    (University POLITEHNICA Timisoara, 2023) Jeremić, Dejan; Radić, Nebojša; Vučetić, Nikola; Kiss, Imre
    To usethe laminated composite plates efficiently, it is necessary to develop appropriate analysis theories to predict accurately their structural and dynamical behavior. The analysis of the behavior of the laminated plates is an active research area because of their complex behavior. The structural instability becomes an important concern in a reliable design of composite plates. The majority of the investigations on laminated plates utilize either the classical lamination plate theory (CLPT), or the first-ordershear deformation theory (FSDT). Various geometries of the plates subjected to compressive load are studied. The present work deals about a buckling analysis of simply supported symmetric composite plate with four layers. It is assumed that composite plate is surrounded by external elastic fundation. Composite plate is modeled by the finite element method and subjected to biaxial compression load. Governing equations are derivedbased on Classical Laminated Plate Theory (CLPT) and computed critical buckling loads were compared with numerical results.
  • Сличица
    Ставка
    INTEGRITY ASSESSMENT OF AN AIRCRAFT CYLINDER ASSEMBLY WITH A CRACK
    (Associated Publishers, 2022) Vučetić, Nikola; Jovičić, Gordana; Antunović, Ranko; Sovilj-Nikić, Sandra; Košarac, Aleksandar; Jeremić, Dejan
    The repeatability of the air-cooled piston engine cylinder assembly failure due to a crack in the cylinder head, as well as its severity from the aspect of crew and passenger safety were the main motives for our research. In this paper an integrity assessment of a cylinder assembly with a crack was performed. By modeling cracks of different lengths in the cylinder head and considering the values of stress intensity factors and J-integral values at a given crack length on the one hand and determining the critical values of these fracture mechanics parameters on the other hand, the stability of the crack was examined. As part of the research, the dependence of the crack length on the stress intensity factor was established. The methodology proposed in this paper can be adapted to assess the integrity of other similar structural elements
  • Сличица
    Ставка
    INVESTIGATION OF VIBRATION RESPONSE OF ORTHOTROPIC DOUBLENANOPLATE SYSTEM SUBJECTED TO INITIAL IN-PLANE PRELOAD
    (University POLITEHNICA Timisoara, 2019) Radić, Nebojša; Jeremić, Dejan
    Analytical methods are employed and explicit solutions for vibrational frequency are obtained for orthotropic doublenanoplate system subjected to an in-plane magnetic field for various boundary conditions. The nonlocal governing equations of motion are derived via Hamilton’s principle with the consideration the Eringen’s differential nonlocal elastic law. Effects of initial preload (compression and tension), magnetic field strength, size of nanoplate, and boundary conditions on vibrational frequency are presented.
  • Сличица
    Ставка
    ISPITIVANJE ZAMORNIH KARAKTERISTIKA LEGURE ALUMINIJUMA 242.0 S CILJEM PROCJENE INTEGRITETA AVIONSKOG CILIDARSKOG SKLOPA SA PRSLINOM
    (Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2022) Vučetić, Nikola; Jovičić, Gordana; Antunović, Ranko; Milovanović, Vladimir; Krstić, Branimir; Jeremić, Dejan; Golubović, Dušan; Milutinović, Miroslav; Prodanović, Saša
    U cilju procjene integriteta cilindarskog sklopa avionskog motora Lycoming IO-360-B1F usljed pojave prsline na glavi cilindra potrebno je izvršiti niz eksperimentalnih ispitivanja legure aluminijuma 242.0 kao sastavnog materijala glave cilindra, među kojima je ispitivanje zamornih karakteristika na sobnoj i na povišenoj temperaturi. Dobijeni rezultati korišćeni su kao ulazni podaci u numeričkoj strukturnoj analizi razmatranog cilindarskog sklopa. Cilj ispitivanja materijala na zamor jeste odrediti dinamičku čvrstoću, odnosno najveći dinamički napon koji materijal pri određenom broju promjena opterećenja može da izdrži, a da pri tome ne dođe do loma.
  • Сличица
    Ставка
    MECHANICAL BUCKLING OF DOUBLE-LAYERED GRAPHENE SHEETS EMBEDDED IN AN ELASTIC MEDIUM USING A NONLOCAL NEW FIRST-ORDER DEFORMATION THEORY
    (University POLITEHNICA Timisoara, 2017) Radić, Nebojša; Jeremić, Dejan
    This paper investigates the buckling behavior of double-layered graphene sheets (GSs) with vaious boundary conditions. It is assumed that two graphene sheets are bonded by an internal elastic medium and surrounded by external elastic fundation. Governing equations are derived based on new first-order sher deformation theory (NFSDT), while the expressions for the buckling load are given in explicit form for a graphene sheets with all edges simply supported (SSSS) and all edges clamped (CCCC). The equations of equilibrium of the nonlocal model have been derived by using the vertical displacement method. Two characteristic types of buckling are considered (in-phase buckling and out-of-phase buckling). The influence of small scale coefficient, aspect ratio, stiffness of internal elastic medium and external elastic fundation on the nonlocal buckling load is explained. Keywords: Analytical modelling, Buckling, Nano-structures
  • Сличица
    Ставка
    ON THE DIVERSITIES OF MULTIVARIABLE CONTROL SYSTEMS
    (Faculty of Mechanical Engineering, University of East Sarajevo, 2018-11) Prodanović, Saša; Nedić, Novak; Dubonjić, Ljubiša; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    Successful system control can`t be achieved without taking into account system nature. Present paper contain overview of control strategies for various multivariable systems. Regarding the mathematical model, order of system and eventual presence of dead time have high influence on the choice of method, which can ensure appropriate design of decoupler and controller. All in order to ensure desired dynamical behaviour of system. Due to that, it is very important to recognize if controlled object is mechanical system or industrial process. Systems with two inputs and two outputs has been illustrated here. Consideration has been supported and presented by appropriate simulations from relevant investigations.
  • Сличица
    Ставка
    POČETNA ISTRAŽIVANJA S CILJEM RAZVOJA METODOLOGIJE ZA PROCJENU INTEGRITETA CILINDARSKOG SKLOPA AVIONSKOG KLIPNOG MOTORA
    (Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2018) Vučetić, Nikola; Jovičić, Gordana; Milovanović, Vladimir; Krstić, Branimir; Rakić, Dragan; Tomović, Radoslav; Antunović, Ranko; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    U radu je dat pregled istraživanja mehaničkih otkaza različitih strukturnih elemenata vazduhoplova, kao u učestalost pojedinih mehanizama otkaza. Naveden je konkretan problem pucanja glave cilindra avionskog vazdušno hlađenog klipnog motora, te je predstavljen plan i cilj istraživanja u cilju razvoja metodologije za procjenu integriteta cilindarskog sklopa. U okviru planiranih istraživanja neophodno bi bilo izvršiti eksperimentalnu analizu mehaničkih karakteristika legure aluminijuma 242.0 na sobnoj i povišenoj temperaturi, kao i numeričku analizu cilindarskog sklopa. Prikazani su očekivani rezultati istraživanja, kao i zaključna razmatranja vezana za značaj samog istraživanja.
  • Сличица
    Ставка
    POSTROJENJA ZA PROIZVODNJU SEKUNDARNIH ENERGENATA OD DRVNOG OTPADA – KAPACITETI I MOGUĆNOSTI NA PODRUČJU ZENIČKO – DOBOJSKOG KANTONA
    (Mašinski fakultet Istočno Sarajevo, Univerzitet u Istočnom Sarajevu, 2018) Halilović, Velid; Vasković, Srđan; Musić, Jusuf; Knežević, Jelena; Balić, Besim; Softić, Jasmin; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    Utvrđivanje kapaciteta proizvodnje sekundarnih energenata na području Zeničko-dobojskog kantona pruža važno uporište za detaljnije i racionalnije planiranje korištenja drvnog otpada iz različitih izvora, koji nastaje na navedenom području. U ovom radu istražene su i prikazane prednosti korištenja sekundarnih energenata u odnosu na fosilna goriva, i to sa ekonomskog, ekološkog i energetskog aspekta. U cilju prikupljanja podataka kreiran je anketni upitnik sa konkretnim pitanjima vezanim za proizvodnju sekundarnih energenata na koja su odgovore dali odgovorna lica subjekata koji su obuhvaćeni istraživanjem. Rezultati rada pokazuju da potencijal proizvodnje sekundarnih energenata na području Zeničko-dobojskog kantona ne koristi se na zadovoljavajućem nivou. Maksimalni kapaciteti proizvodnje se ni približno ne ostvaruju. Zaključci govore da je proizvodnja cijepanog drveta tek 49% od maksimalnog kapaciteta, peleta i briketa oko 60%.
  • Сличица
    Ставка
    PROCESS OF IMPROVING THE ENTREPRENEURIAL COMPETENCIES
    (Mašinski fakultet, Univerzitet u Istočnom Sarajevu, 2018) Moljević, Slaviša; Gojković, Ranka; Nestić, Snežana; Orašanin, Goran; Tihić, Dino; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    Entrepreneurship, through the creation of new jobs, increased innovation and poverty reduction, has been recognized as the main factor in economic and social development. In this paper, special attention is paid to the development of entrepreneurial knowledge, skills and attitudes through entrepreneurial education. There is an increasing awareness that entrepreneurial skills, knowledge and attitudes can be learned, leading to a more visible development of the entrepreneurial mindset and entrepreneurial culture in individuals and society as a whole. The paper presents the process of improvement of entrepreneurial competences among students of engineering disciplines. The process of improvement represents the approaches developed within Erasmus + REBUS projects.
  • Сличица
    Ставка
    PRORAČUN TROSEGMENTNOG STUBA ZA JAVNU RASVJETU
    (Mašinski fakultet, Univerzitet Istočno Sarajevo, 2018) Trifković, Spasoje; Milutinović, Miroslav; Golijanin, Saša; Golubović, Dušan; Košarac, Aleksandar; Jeremić, Dejan
    U radu je izvršen statički proračun stuba sa za javnu rasvjetu sa proračunom čvrstoće stuba u kritičnim presjecima za najnepovoljniji slučaj opterećenja stuba. Visina stuba je 8m sa tri segmenta iste dužine prečnika 133mm, 108mm i 76mm sa dvije noseće lire visine dužine 1,5m.
  • Сличица
    Ставка
    The Böhler’s angle in population of central Serbia – a radiological study
    (MDPI, 2018) Živanović-Mačužić, Ivana; Vulović, Maja; Vojinović, Radiša; Jovanović, Milan; Radunović, Aleksandar; Milev, Boško; Cvetković, Aleksandar; Stojiljković, Miloš; Milošević, Bojan; Ivošević, Anita; Aksić, Milan; Simović, Aleksandra; Jeremić, Dejan
    Background/Aim. The values of the Böhler’s angle (BA) are relevant parameters for diagnosis, management and prognosis of the calcaneal fracture and the outcome. Range of normal values of Böhler’s angle (BA) in adults varies depending on the examined population, age, gender or ethnicity. The aim of this study was to determine the range of normal values of the Böhler’s angle in the central part of Serbia. Methods. The lateral foot radiographs of 225 subjects (111 males and 114 females) without calcaneal fractures, divided into 6 age groups were observed to determine the normal values of the Böhler’s angle by using the IMPAX 6.5.2.114 Enterprise software. Obtained values for Böhler’s angle were compared among gender and groups using appropriate statistical tests. Results. The mean of Böhler’s angle in observed population was 34.06°, ranging from 25.1° to 49.5° and was higher in males than in females included in our study. Gender difference was statistically significant. The distribution of the mean BA across the age groups showed tendency of decreasing with age and the highest BA was found in the youngest group. Conclusion. The findings presented in this paper confirmed the existence of wide range of BA values as well as its gender and age differences.
  • Сличица
    Ставка
    THE INFLUENCE OF CARBON FIBER ORIENTATION ANGLE ON BUCKLING PROPERTIES OF FOUR–LAYER SYMMETRIC LAMINATE UNDER BIAXIAL COMPRESSION
    (University POLITEHNICA Timisoara, 2022) Jeremić, Dejan; Radić, Nebojša; Vučetić, Nikola; Kiss, Imre
    The present work focused on the buckling of four–layer symmetric laminate subjected to biaxial compression. Governing equations are derived based on Classical Laminated Plate Theory (CLPT). The composite plates are bonded by an internal elastic medium and surrounded by external elastic foundation. The influences of carbon fiber orientation angle and aspect ratio on critical buckling load are demonstrated for symmetric laminate. We analyzed four lamination scheme which fiber angle orientation is equal to 0°, 30°, 45° and 90°.
  • Сличица
    Ставка
    The influence of different lamina positions on buckling properties of composites plates under biaxial compression
    (2019) Jeremić, Dejan; Radić, Nebojša
    The present work focused on the buckling of composite plates subjected to biaxial compression using classical laminated plate theory (CLPT). The two composite plates are bonded by an elastic medium. Classical laminated plate theory (CLPT) is utilized for deriving the governing equations. Difference between 4-ply symmetric lamination scheme with different material properties and fiber orientation angle (0° and 30°) is shown. The study show that the mechanical properties of the composite materials depending on the fiber orientation angle and lamina positions.
  • Сличица
    Ставка
    Uticaj interakcije lokalnog i distorzionog oblika gubitka stabilnosti tankozidih profila otvorenog poprečnog presjeka na smanjenje nosivosti u postkritičnoj fazi
    (Institut IMK "14. oktobar", 2012) Radić, Nebojša; Trifković, Spasoje; Jeremić, Dejan; Milutinović, Miroslav; Gašić, Milomir
    U radu se razmatra problem određivanja vrijednosti lokalnog i distorzionog kritičnog napona tankozidih profila otvorenog poprečnog presjeka. Kod tankozidih nosača gubitak stabilnosti se dešava u zoni elastičnosti i pri relativno malim vrijednostima kritičnog napona. Sa povećanjem opterećenja u postkritičnoj fazi pri određivanju nosivosti potrebno je uzeti u obzir interakciju lokalnog i distorzionog oblika jer dolazi do značajnog smanjenja nosivosti u odnosu na slučaj kada se ta interakcija zanemaruje.
  • Сличица
    Ставка
    Vibration analysis of orthotropic double-nanoplate system subjected to unidirectional in-plane magnetic field with various boundary conditions
    (International Organization Of Scientific Research (IOSR), 2018) Radić, Nebojša; Jeremić, Dejan; Mijatović, Biljana
    The present study investigates the vibration behaviour of orthotropic double-nanoplate system subjected to an in-plane magnetic field and in-plane preload with various boundary conditions. The nonlocal governing equations of motion are derived via Hamilton’s principle with the consideration the Eringen’s differential nonlocal elastic law, where the influences of the Lorenz magnetic force are obtained via a Maxwell’s relation. Analytical methods are employed and explicit solutions for vibrational frequency are obtained for orthotropic double-nanoplate system for various boundary conditions. The obtained results are compared with the results available in the literature to check their validation. Effects of nonlocal parameter, magnetic field strength, number of half waves, initial preload (compression and tension), size of nanoplate and boundary conditions on vibrational frequency are presented.