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1.
Virtualni inženiring I : komponente virtualnega inženiringa, zapiski predavanj
Gorazd Hren, 2024

Abstract: Zapiski predavanj so namenjeni študentom, ki se vsakodnevno in vedno bolj srečujejo z uporabo razvojnih računalniških orodij pri designu izdelkov. Izredno kakovostne in tudi kompleksnejše računalniške aplikacije omogočajo simulacije in analize inženirskih rešitev preden so te implementirane kot prototipi ali končni izdelki. Virtualni inženiring najprej tvorijo komponente za ustvarjanje geometrije, sistemi CAD in povratni inženiring s sistemi skeniranja, ki predstavlja osnovo za nadaljnje postopke razvoja izdelkov. Naslednje komponente so izdelava virtualnih prototipov v navideznem okolju ali fizičnih prototipov, katerih izdelava je dandanes večinoma izvedena s 3D tiskom. Izrednega pomena v razvoju izdelkov so numerične simulacije, ki omogočajo analize -trdnosti, dinamike tekočin in gibanja mehanizmov - glede na robne pogoje. S pridobljenimi podatki lahko načrtujemo proizvodnjo, logistiko, kontrolo kakovosti, ergonomijo, marketing, preden gre izdelek v končno izdelavo. Vse te komponente povezujejo informacijski sistemi DMU, PLM, ki omogočajo in tudi določajo organizacijsko strukturo razvojnega dela, opisanem v zadnjem poglavju: Virtualni razvoj izdelkov.
Keywords: virtualni inženiring, sistemi CAD, povratni inženiring, numerične simulacije, virtualni razvoj izdelkov
Published in DKUM: 10.05.2024; Views: 281; Downloads: 16
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2.
Uporaba spektralne analize v energetiki : diplomsko delo
Sara Božnik, 2024, undergraduate thesis

Abstract: V diplomskem delu je predstavljen splošni pregled uporabe spektralne analize v energetiki s poudarkom na problematiki hrupa in vibracij v energetskih postrojih. Razvili smo kodo za izvedbo spektralne analize zvoka na podlagi hitre Fouriereve transformacije v računalniškem okolju Matlab in jo uporabili na merilnih podatkih zvoka. V ta namen smo predstavili potrebno matematično ozadje za razumevanje Fouriereve analize. Ker so dandanes računalniki in druge pametne naprave široko dostopne, smo preizkusili tudi izbran računalniški program in mobilno aplikacijo, ki ne zahtevata znanja programiranja.
Keywords: spektralna analiza, hitra Fouriereva transformacija, zvok, hrup
Published in DKUM: 18.03.2024; Views: 336; Downloads: 43
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3.
Izpusti toplogrednih plinov in cenovna upravičenost električnih osebnih avtomobilov v primerjavi z osebnimi avtomobili na fosilna gradiva : diplomsko delo
Matevž Kokovnik, 2023, undergraduate thesis

Abstract: Ideja za diplomsko se je porodila iz strateške vizije Evropske komisije za doseganje podnebno nevtralnega gospodarstva do leta 2050, katere del je tudi prepoved prodaje vozil z izpusti CO2 od leta 2035 dalje. V prvem delu naloge sta predstavljeni proizvodnja in razgradnja električnih avtomobilov ter njihovi sestavni deli. Podrobneje sta predstavljena tudi elektromotor in baterija oz. pogonski akumulator, ki predstavljata glavno razliko med električnimi avtomobili in avtomobili z notranjim izgorevanjem. V osrednjem delu naloge sta predstavljeni ekološka in ekonomska upravičenost električnih vozil v primerjavi z vozili na notranje izgorevanje. Proizvodnja električnega vozila v ozračje izpusti večje količine emisij CO2 kot proizvodnja avtomobila na notranje izgorevanje, vendar pa električni avtomobili v času vožnje v ozračje ne izpuščajo emisij CO2 oz. so te emisije posredne in nastanejo pri proizvodnji električne energije. Prav tako so električna vozila dražja od vozil na notranje izgorevanje, vendar pa je vožnja z njimi cenejša. V zadnjem delu diplomske naloge so predstavljene možne rešitve za zagotavljanje dodatnih potreb po električni energiji, ki jo bodo potrebovala električna vozila. Pomembno je, da so viri za zagotavljanje dodatnih potreb po električni energiji brez oz. nizko ogljični.
Keywords: električni avtomobili, ekološka upravičenost, ekonomska upravičenost, primerjava različnih vrst vozil, dolgoročna strategija za leto 2050
Published in DKUM: 18.03.2024; Views: 306; Downloads: 28
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4.
Opis delovanja spodnjesavske verige hidroelektrarn in nadgradnja pomožne aplikacije za avtomatsko daljinsko vodenje hidroelektrarn z vključitvijo HE Vrhovo : magistrsko delo
Aljaž Prah, 2023, master's thesis

Abstract: Magistrsko delo se osredotoča na lastnosti in obratovalne značilnosti hidroelektrarn na reki Savi, zlasti na hidroelektrarne na spodnji Savi, ki jih upravlja Center vodenja GEN. Opisana je tudi lastniška organiziranost hidroelektrarn v celotni dolžini reke v Sloveniji. Poleg omejitev obratovanja je hidrologija ključni dejavnik pri načrtovanju proizvodnje hidroelektrarn. Vključitev hidroelektrarne HE Vrhovo v aplikacijo za vodenje je pomembna zaradi njene čelne vloge v verigi hidroelektrarn na spodnji Savi. Z uporabo enoagregatnega modela, ki temelji na preteklih obratovalnih stanjih, je bilo v aplikacijo vključeno obratovanje HE Vrhovo. Nadgradnja aplikacije za avtomatsko daljinsko vodenje hidroelektrarn na spodnji Savi omogoča boljše planiranje in vpogled v dnevno obratovanje hidroelektrarne. Tako lahko dispečerji pripravijo natančen potek obratovanja HE Vrhovo in optimizirajo moč na celotni verigi hidroelektrarn na spodnji Savi. S tem se je povečal finančni izplen celotne verige v času višjih cen električne energije.
Keywords: hidroelektrarne, enoagregatni model, optimizacija vodenja
Published in DKUM: 15.01.2024; Views: 362; Downloads: 26
.pdf Full text (6,03 MB)

5.
Influence of Numerical Mesh Type on Airfoil Aerodynamic Characteristics
Marko Pezdevšek, Matej Fike, Andrej Predin, Gorazd Hren, 2019, published scientific conference contribution

Abstract: In this paper, we will examine how different mesh types affect the aerodynamic characteristic of an airfoil. The airfoil used for this paper was the NREL S809. Three different mesh types were created, a blocked structured mesh, an unstructured mesh and a hybrid mesh containing a blocked structured mesh near the surface of the airfoil and an unstructured mesh on the outside perimeter. Steady state simulations were performed for angles of attack between 0°and 22°. Lift and drag coefficient for all created meshes were compared to experimental results from literature. From angles of attack between 2° and 8° all three meshes predict similar lift and drag coefficients. We encountered problems with convergence for the unstructured mesh at angles of attack higher than 8°. Structured and hybrid mesh had similar lift and drag coefficients across all angles of attack.
Keywords: computational fluid dynamics, NREL S809, structured mesh, unstructured mesh, hybrid mesh
Published in DKUM: 04.12.2023; Views: 318; Downloads: 15
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6.
Experimental and Numerical Research of Micro Wind Turbine for Low Wind Speeds
Matej Fike, Marko Pezdevšek, Andrej Predin, Gorazd Hren, 2019, published scientific conference contribution

Abstract: In this paper, experimental and numerical study of micro wind turbine for low wind speeds is presented. Numerical simulations were performed for two turbines with different blades at various wind speeds. The first geometry was NTNU turbine and the second was modified NTNU turbine with shorter blades. Results from the numerical study showed that more efficient with higher power coefficient is turbine with modified blades.
Keywords: wind turbine, NREL S826, CFD, power coefficient, structured mesh
Published in DKUM: 04.12.2023; Views: 269; Downloads: 14
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7.
Lost Energy of Water Spilled over Hydropower Dams
Andrej Predin, Matej Fike, Marko Pezdevšek, Gorazd Hren, 2021, original scientific article

Abstract: The present paper presents a view of water spilled over hydropower plants as an energy loss. In the current climate conditions, flood events are becoming more frequent due to human impact on the environment; water spills are also more frequent, which means more and more energy is lost. How much water is spilled and, consequently, how much energy is lost is shown in the present article on the chain of power plants on the Sava River in the five years from 2015 to 2019. An analytical assessment of the current situation in the lock was carried out, which showed that the available water through the locks could be used efficiently. The paper presents a case study of one overflow event lasting 48 h. The calculated theoretical losses of energy (of spilled water) and possible technical implementation for capturing losses are given. The proposed technical implementation is based on established technology, so we could expect that the approach is feasible. The results show that the estimated spilled water energy potential reaches about 40% of the actual spilled water or energy lost.
Keywords: energy loss, spilled water energy, hydropower
Published in DKUM: 13.11.2023; Views: 228; Downloads: 14
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8.
Energy source replacement in a thermal power plant
Matej Fike, Andrej Predin, 2022, original scientific article

Abstract: In Slovenia, approximately one third of electricity is produced in thermal power plants. Electricity prices have risen sharply recently. There are several reasons for this. One of them is the large increase in the price of CO2 coupons that thermal power plants have to buy, since they emit large amounts of greenhouse gas into the environment during the production of electricity. Emissions of the greenhouse gas CO2 are the result of burning fossil fuels, in this case coal. We want to use renewable energy sources to replace fossil fuels and reduce greenhouse gas emissions. More than half of Slovenia is covered with forest, and as a result, wood biomass energy represents a great energy potential. One possibility is the use of wood biomass in a classic thermal power plant for the production of electricity. This contribution presents the energy potential of Slovenian forests, before evaluating the replacement of the energy source in the existing coal-based thermal power plant with wood biomass. It has been discovered that there is enough wood biomass in Slovenia, and that all the electricity that is currently produced from coal can be produced from wood biomass. The cost of wood biomass is higher than the cost of coal. By changing the energy source, we save on the purchase of CO2 coupons. Therefore, the use of wood biomass represents an economically justified energy source for the production of electricity.
Keywords: wood biomass, thermal power plant, electricity production
Published in DKUM: 30.10.2023; Views: 398; Downloads: 5
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9.
Estimation of real driving emissions based on data from OBD
Matej Fike, Andrej Predin, 2022, published scientific conference contribution abstract

Keywords: vehicle, diesel engine, exhaust emission levels, real driving emissions
Published in DKUM: 30.10.2023; Views: 343; Downloads: 5
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10.
Energy of water spilled over hydropower dams
Matej Fike, Marko Pezdevšek, Gorazd Hren, Andrej Predin, 2022, published scientific conference contribution abstract

Keywords: hydropower, spilled water energy, energy loss, hydropower dams
Published in DKUM: 30.10.2023; Views: 303; Downloads: 4
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