| | SLO | ENG | Piškotki in zasebnost

Večja pisava | Manjša pisava

Iskanje po katalogu digitalne knjižnice Pomoč

Iskalni niz: išči po
išči po
išči po
išči po
* po starem in bolonjskem študiju

Opcije:
  Ponastavi


1 - 10 / 138
Na začetekNa prejšnjo stran12345678910Na naslednjo stranNa konec
1.
2.
Virtualni inženiring I : komponente virtualnega inženiringa, zapiski predavanj
Gorazd Hren, 2024

Opis: 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.
Ključne besede: virtualni inženiring, sistemi CAD, povratni inženiring, numerične simulacije, virtualni razvoj izdelkov
Objavljeno v DKUM: 10.05.2024; Ogledov: 82; Prenosov: 7
.pdf Celotno besedilo (5,67 MB)
Gradivo ima več datotek! Več...

3.
4.
5.
A Survey on the State-of-the-Art and Future Trends of Multilevel Inverters in BEVs
Alenka Hren, Mitja Truntič, Franc Mihalič, 2023, pregledni znanstveni članek

Opis: All electric vehicles are the only way to decarbonize transport quickly and substantially. Although multilevel inverters have already been used in some transportation modes, they are rarely used in road transportation, especially in light-duty passenger BEVs. With the transition to a high 800-V DC link to extend the driving range and enable extreme fast charging, the possibility of using multilevel inverters in commercial light-duty passenger BEVs becomes feasible. Higher efficiency, higher power density, better waveform quality, lower switching frequency, the possibility of using low-rated switches, and inherent fault tolerance are known advantages of multilevel inverters that make them an efficient option for replacing 2-level inverters in high DC link passenger BEVs. This paper discusses high DC link voltage benefits in light-duty passenger BEVs, presents the state-of-the-art of different conventional multilevel inverter topologies used in BEVs, and compares them with conventional 2-level inverters from different aspects and limitations. Based on commercial upper-class passengers’ BEV data and a review of multilevel inverters on the market, future trends and possible research areas are identified.
Ključne besede: multilevel inverters, MLI, electric vehicle, EV, passengers’ battery electric vehicle, BEV, extreme fast charging, XFC, higher voltage batteries, WBG semiconductors
Objavljeno v DKUM: 26.03.2024; Ogledov: 158; Prenosov: 8
.pdf Celotno besedilo (2,07 MB)
Gradivo ima več datotek! Več...

6.
Study on commercially available membranes for alkaline direct ethanol fuel cells
Michaela Roschger, Sigrid Wolf, Andreas Billiani, Kurt Mayer, Maša Hren, Selestina Gorgieva, Boštjan Genorio, Viktor Hacker, 2023, izvirni znanstveni članek

Opis: This study provides a comparison of different commercially available low-cost anion exchange membranes (AEMs), a microporous separator, a cation exchange membrane (CEM), and an anionic-treated CEM for their application in the liquid-feed alkaline direct ethanol fuel cell (ADEFC). Moreover, the effect on performance was evaluated taking two different modes of operation for the ADEFC, with AEM or CEM, into consideration. The membranes were compared with respect to their physical and chemical properties, such as thermal and chemical stability, ion-exchange capacity, ionic conductivity, and ethanol permeability. The influence of these factors on performance and resistance was determined by means of polarization curve and electrochemical impedance spectra (EIS) measurements in the ADEFC. In addition, the influence of two different commercial ionomers on the structure and transport properties of the catalyst layer and on the performance were analyzed with scanning electron microscopy, single cell tests, and EIS. The applicability barriers of the membranes were pointed out, and the ideal combinations of membrane and ionomer for the liquid-feed ADEFC achieved power densities of approximately 80 mW cm–2 at 80 °C.
Ključne besede: bioethanol, electrodes, fluoropolymers, ionomers, membranes
Objavljeno v DKUM: 26.03.2024; Ogledov: 105; Prenosov: 7
.pdf Celotno besedilo (5,64 MB)
Gradivo ima več datotek! Več...

7.
Life Cycle Assessment of Pilot-Scale Bio-Refining of Invasive Japanese Knotweed Alien Plant towards Bio-Based Bioactive Compounds
Robert Hren, Katerina Naumoska, Urška Jug, Lidija Čuček, Blaž Likozar, Uroš Novak, Annamaria Vujanović, 2023, izvirni znanstveni članek

Opis: Japanese knotweed is an invasive alien plant species with characteristic rapid expansion in Europe and North America and resistance to extermination. It displaces autochthonous biodiversity and causes major damage to infrastructure, thus causing global ecological and economic damage. The Japanese knotweed plant is usually eradicated using various chemical, biological, or mechanical techniques, which at a large scale include heavy equipment, usually followed by incineration. Therefore, excavation is preferred to eradication techniques, and as a biomass waste recovery method due to the extraction of high-value biocompounds. This is supported by the fact that the Japanese knotweed possesses various bioactive compounds with beneficial effects on human health. Its rhizome bark extract produces strong and stable antioxidant activity over time, as well as apoptotic, antibacterial, and other beneficial activities. In this work, an environmental impact assessment, including greenhouse gas footprint, acidification, eutrophication, and ecotoxicity for extraction route of the Japanese knotweed rhizome bark, is performed. A comparative case study between the lab-based and proposed pilot-scale production of active added-value extract was evaluated. The results show the pilot-scale production exhibits lower environmental burdens, mainly due to greater electricity requirements for the lab-scale alternative.
Ključne besede: Japanese knotweed rhizome bark extract, invasive alien plant species, bioactive compounds, lab-scale, pilot-scale, life cycle assessment (LCA), environmental burden assessment
Objavljeno v DKUM: 19.03.2024; Ogledov: 134; Prenosov: 7
.pdf Celotno besedilo (1,31 MB)
Gradivo ima več datotek! Več...

8.
Numerical analysis of a wind turbine blade with different software
Gorazd Hren, 2019, izvirni znanstveni članek

Opis: The development of wind power generation technology recognises the wind turbine blade design and manufacturing as crucial for its performance. The laboratory size wind turbine blade was analysed, considering the 3D printing plastic material for blades. Applying the structural dynamic equations of blades, the aero-elastic model of the rotating rotor and the numerical simulation method of the deflections are presented under the aerodynamic loads and centrifugal forces. Based on the parameters of aerofoil and the geometrical parameters of blade, 3D model of the blade was established with the modelling software. Then the model was introduced into computational flow dynamics software to carry out the loads on the blade and further into numerical structural analysis. The analysis was performed in two different software packages. Design of wind turbine blades depends on high precision, reliable and robust numerical predictions of performance where the plug-in software is found to be inadequate for nontrivial problems.
Ključne besede: computational fluid dynamics, numerical analysis, structural analysis, wind turbine blade
Objavljeno v DKUM: 22.02.2024; Ogledov: 203; Prenosov: 14
.pdf Celotno besedilo (1,68 MB)
Gradivo ima več datotek! Več...

9.
Cavitation erosion modelling : comparison of different driving pressure approaches
Luka Kevorkijan, Marko Pezdevšek, Ignacijo Biluš, Gorazd Hren, 2023, izvirni znanstveni članek

Opis: In this paper we compared different driving pressure approaches to calculate the cavitation potential energy from a source, which is transferred to a surface. The first approach used the reference pressure, the second approach used the pressure calculated at each timestep with no averaging, the third approach used the averaged pressure values from all timesteps included in one shedding cycle, and the last approach used pressure values from the steady state simulations results. The results show that for all formulations the averaged pressure values and steady state pressure values give similar results in terms of mean potential power distribution on the hydrofoil surface as in absolute values. The reference pressure approach gave similar results for the derivative and divergence formulation while for the source term the mean potential power distribution on the hydrofoil surface differs and the maximums were near the leading edge. The approach where we used no pressure averaging gave adequate results in terms of mean potential power distribution but differs from other approaches in absolute values which were considerably lower for all potential power formulations.
Ključne besede: cavitation, erosion potentional, driving pressure, numerical simulations
Objavljeno v DKUM: 21.02.2024; Ogledov: 252; Prenosov: 9
.pdf Celotno besedilo (796,29 KB)
Gradivo ima več datotek! Več...

10.
Primerjava sistemov CAD (Solidworks in Onshape) pri 3D modeliranju : diplomsko delo
Jan Gabrijel, 2023, diplomsko delo

Opis: Programska oprema za računalniško podprto konstruiranje je stalnica pri razvoju izdelkov in ima velik vpliv na različne tehnologije in sisteme proizvodnje v raznovrstnih panogah. Razvoj in uporaba teh sistemov je ključno spremenila tradicionalne metode razvoja izdelkov vse od prototipa do končne proizvodnje. Čeprav se teoretske metode modeliranja ne spreminjajo veliko, je njihov razvoj v zadnjem času predvsem usmerjen na prilagajanje vedno močnejši strojni opremi, kakovosti prikazovanja in predvsem soočanja s številnimi izzivi kot so dostopnost do skupnih podatkovnih baz, komunikacija preko računalniških mrež, težave z verzijami ter stroški strojne opreme in licenciranja. Novejša programska oprema CAD v oblaku, uporabnikom ponuja novo in drugačno storitev, ki ne zahteva namestitve programske opreme in licenciranje, in je enostavno dosegljiva iz internetnega prikazovalnika. Programska oprema v oblaku na splošno sicer še ne odgovarja na vsa vprašanja, ki se ob pojavljajo ob uporabi, vendar že prinaša nove pristope, ki nakazujejo smernice drugačne uporabe sistemov CAD. V diplomski nalogi smo na primeru geometrije sklopa parnega stroja primerjali sistema CAD: Solidwoks kot tradicionalni sistem CAD in Onshape kot primer sistema CAD v oblaku. Namen diplomske naloge je uporabniška izkušnja dveh programskih sistemov CAD na enakem izdelku katere rezultat so številni dejavniki, ki jih je potrebno upoštevati. Ugotovimo lahko, da je uporabniška izkušnja zelo podobna, a je prednost, ob zagotovljeni varnosti podatkov na strani oblačnih storitev.
Ključne besede: sistemi CAD, modeliranje, računalništvo v oblaku
Objavljeno v DKUM: 16.01.2024; Ogledov: 277; Prenosov: 14
.pdf Celotno besedilo (2,95 MB)

Iskanje izvedeno v 0.31 sek.
Na vrh
Logotipi partnerjev Univerza v Mariboru Univerza v Ljubljani Univerza na Primorskem Univerza v Novi Gorici