| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


1 - 10 / 1407
First pagePrevious page12345678910Next pageLast page
1.
International energy security risk index - analysis of the methodological settings
Iztok Podbregar, Goran Šimić, Mirjana Radovanović, Sanja Filipović, Polona Šprajc, 2020, original scientific article

Abstract: The main objective of this paper is to analyze model settings of the International Energy Security Risk Index developed by the U.S. Chamber of Commerce. The study was performed using stepwise regression, principal component analysis, and Promax oblique rotation. The conclusion of the regression analysis shows that Crude Oil Price and Global Coal Reserves are sufficient to explain 90% of the variance of the Index. However, if a model that explains 100% of the variance of the Index is chosen and other variables are added, Global Coal Reserves loses importance due to the presence of other parameters in which it is contained. Regardless of the chosen model of analysis, it is evident that there is room for revising the Index and removing variables that do not contribute to its precision. The research showed that the main disadvantage of the variables that make up the Index rests with the fact that the variables are of different degrees of generality, that is, one parameter is contained in other parameters (unclear which other). The research covers data for 25 countries over a 26-year period, with the first year of the research being 1980 and the last 2016 (the latest available report).
Keywords: international energy security risk index, analysis, stepwise regression, principal component analysis, Promax oblique rotation
Published in DKUM: 04.02.2025; Views: 0; Downloads: 3
.pdf Full text (1,04 MB)
This document has many files! More...

2.
The international energy security risk index in sustainable energy and economy transition decision making - a reliability analysis
Iztok Podbregar, Goran Šimić, Mirjana Radovanović, Sanja Filipović, Damjan Maletič, Polona Šprajc, 2020, original scientific article

Abstract: The world economy and society are in a complex process of transition characterized by a high degree of uncertainty. Therefore, further development and management of the transition will largely depend on the quality of the decisions made and, accordingly, on the decision-making process itself. The main goal of this study is to analyze the reliability of International Energy Security Risk Index as a tool to support the process of energy and economy transition decision making, as closely related and highly interdependent phenomena. The index is composed of 29 aggregated variables (grouped into eight categories), and the research is conducted on a research sample of 25 countries over a period of 36 years. The reliability assessment is performed by using Multiple Regression Analysis. Multicollinearity test, plus Multicollinearity test with Variance Inflation Factors, is used for methodological verification. The test results indicate a high degree of unreliability of the Index, as is concluded based on the observed errors in its methodological settings. These errors primarily relate to a high degree of multicollinearity in all 29 variables, whereby independent variables lose their independence and thus jeopardize reliability of the total Index. Out of the eight groups of variables, the fuel imports group is the only one that does not show big methodological errors. The paper presents a recommendation for the improvement of the observed Index (review of the role of individual variables found to be particularly methodologically indicative), as well as a recommendation for different distribution of weighting coefficients.
Keywords: energy and economy transition, decision making, international energy security risk index, multiple regression analysis, multicollinearity test, multicollinearity test with variance inflation factors
Published in DKUM: 04.02.2025; Views: 0; Downloads: 2
.pdf Full text (447,82 KB)
This document has many files! More...

3.
Trdnostna analiza variant ogrodja stroja
Mihael Muršec, 2025, master's thesis

Abstract: V magistrskem delu je obravnavano zgornje ogrodje stroja za vezanje lesenih letev v pakete. Izvedena je bila trdnostna analiza obstoječega ogrodja z uporabo metode končnih elementov. Sledil je analitičen preračun obstoječe gibalne navojne zveze. Razvitih je bilo pet novih variantnih rešitev ogrodja, ki so bile trdnostno analizirane. Na podlagi rezultatov analiz in zahtevnika je bila kot najboljša izbrana variantna rešitev številka dve, saj je imela za 21 % manjši poves ogrodja.
Keywords: jeklene konstrukcije, pakirni stroj, trdnostna analiza, navojno vreteno, računalniške simulacije
Published in DKUM: 03.02.2025; Views: 0; Downloads: 10
.pdf Full text (4,50 MB)

4.
Zaposlitev športnikov po končani športni karieri
Nina Klemenčič, 2024, master's thesis

Abstract: Cilj vrhunskih športnikov, ki tekmujejo na najvišjih ravneh tekmovanj, so v večini čim boljši rezultati. Kljub načrtovanju pošportnega življenja športnikov, pa športno kariero lahko predčasno povzročijo poškodba ali druge težave športnika (zdravstvene, finančne, psihološke itd.). Na podlagi uspešnih rezultatov so nekateri športniki že med športno kariero zaposleni kot poklicni športniki, nekateri žal ne. Vsem pa je skupno, da bodo po koncu športne kariere morali stopiti na trg dela in poiskati zaposlitev. Velikokrat na čas do prve zaposlitve vpliva tudi dokončana stopnja izobrazbe, ki so jo športniki dosegli že med samo športno kariero. Nekateri se zaposlijo na področju športa, saj imajo na tem področju največ izkušenj in kompetenc, nekateri na področju izobraževanja, spet drugi pa najdejo povsem drugačno področje zaposlitve, ki ni povezano niti s športom niti s področjem izobraževanja. Namen magistrskega dela je bil ugotoviti področje zaposlitve, ki jo nekdanji športniki opravljajo danes. Zanimalo nas je, ali gre za področje izobraževanja, iz katerega so se izobraževali že med športno kariero, ali gre za področje športa, ali pa so trenutno zaposleni na povsem drugem področju. Magistrsko delo je sestavljeno iz teoretičnega in empiričnega dela. V teoretičnem delu smo opisali področja zaključka športne kariere, poklicne kariere športnika, zaposlitev športnikov v Slovenski vojski in področje iskalcev prve zaposlitve. V empiričnem delu magistrskega dela smo s pomočjo anketnega vprašalnika in dovolj velikega vzorca anketirancev odgovarjali na naslednja raziskovalna vprašanja: Kako športniki sprejemajo dejstva o koncu športne kariere in začetku iskanja zaposlitve, kako je izobrazba povezana s trenutno zaposlitvijo nekdanjih športnikov in kateri dejavniki in na kakšen način vplivajo na zaposlitev športnikov po končani športni karieri. V empiričnem delu smo komentirali in grafično prikazali odgovore anketirancev, ki smo jih med seboj primerjali tudi glede na sekundarno in terciarno stopnjo izobraženosti anketirancev. Prišli smo do ugotovitev, da se je večina nekdanjih športnikov že v času športne kariere dovolj dobro zavedala, da bodo po koncu športne kariere morali čim prej stopiti na trg dela in njihovi dohodki ne bodo več odvisni od športnih rezultatov. Ugotovili smo tudi, da je večina nekdanjih športnikov zaposlena na področju, na katerem so se izobraževali in ne na področju športa. Menimo, da bi se morale Športne zveze in Olimpijski komite Slovenije v prihodnje bolj angažirati in pomagati pri iskanju prve zaposlitve vrhunskim športnikom, ki so zaključili športno pot.
Keywords: zaposlitev, nekdanji športniki, dvojna kariera, poklicna kariera športnika, prva zaposlitev
Published in DKUM: 28.01.2025; Views: 0; Downloads: 3
.pdf Full text (805,85 KB)

5.
6.
Fatigue analysis of axisymmetric chiral cellular structures made out of 316L stainless steel
Žiga Žnidarič, Branko Nečemer, Nejc Novak, Srečko Glodež, 2024, original scientific article

Abstract: Abstract In the proposed study, the fatigue analysis of an axisymmetric chiral cellular structure and its modified form, made of stainless steel 316L, is carried out. The main goal of the original structure geometry was to absorb as much mechanical energy as possible with its auxetic behaviour. However, it was found through testing that its response could be improved by modifying the thickness of the struts through the structure. Representative models for the original and modified geometries were generated using a script adapted for this numerical simulation. Three different types of displacement in the shape of sine waves were used to load the structures. A hexagonal mesh was assigned and determined by convergence analysis. An existing material model with the necessary LCF parameters was assigned in the computational analyses. The data from multiple simulations were recorded and presented in graphs that showed how the fatigue life of the structures changed depending on the level of strain. We also analysed stresses and plastic deformations that occur in the structures. The results showed that, despite a better stress distribution, the fatigue life of the optimised structure was shorter in all cases.
Keywords: cellular structures, chiral structures, fatigue, strain-life approach, numerical analysis
Published in DKUM: 10.01.2025; Views: 0; Downloads: 4
.pdf Full text (8,28 MB)
This document has many files! More...

7.
Energy demand distribution and environmental impact assessment of chitosan production from shrimp shells
Filipa A. Vicente, Robert Hren, Uroš Novak, Lidija Čuček, Blaž Likozar, Annamaria Vujanović, 2024, original scientific article

Abstract: Step towards resilience and sustainability through exploring renewable biomass and waste streams to produce higher-added value products and energy is among key aspects for closing the loops, saving resources, and reducing the resource and emission footprints. In that respective, crustacean shells waste can offer rich spectre of valuable compounds such as proteins, chitin, carotenoids. This waste is produced in large quantities worldwide, thus allowing for commercial valorisation. An overview of technologies is undertaken for more sustainable and environmentally friendly chitosan production via chitin isolation and conversion and compared to the conventional processes. Furthermore, an assessment of the environmental burden and energy demand distribution for conventional and more sustainable alternative processes was performed, based on lab-scale experimental data. Three different chitin extraction routes and three distinct chitosan conversion processes were considered and compared for their greenhouse gas footprint, abiotic depletion, acidification, eutrophication and other potentials. Finally, the energy demand distribution was analysed considering electricity production patterns from three European countries, Slovenia, Portugal and Norway. The results showed that alternatives 3-A and 3-B (conventional eco-solvents - conventional deacetylation with 40 % and 50 % NaOH) generate the lowest environmental burden (184 g CO2 eq./g chitosan). Electricity was the main hotspot of the processes, used either for extraction, plasma treatment or deacetylation. The sensitivity analysis proved that the Norwegian electricity mix has the lowest environmental impact (4.2 g CO2 eq./g chitosan). This study highlights the impact of blue biorefineries by transforming marine waste to valuable biopolymers such as chitin and chitosan.
Keywords: shrimp shells waste, blue biorefinery, value-added products, chitosan, sustainable production, comparative environmental assessment
Published in DKUM: 08.01.2025; Views: 1; Downloads: 1
.pdf Full text (2,16 MB)

8.
Life cycle assessment (LCA) of the impact on the environment of a cosmetic cream with gold nanoparticles and hydroxylated fullerene ingredients
Rebeka Rudolf, Peter Majerič, Zorka Novak-Pintarič, Andrej Horvat, Damjan Krajnc, 2024, original scientific article

Abstract: This review provides a comprehensive Life Cycle Assessment (LCA) of a cosmetic cream to assess the environmental impacts throughout its entire life cycle, from raw material extraction to disposal, using the methodology according to international standards. The LCA was performed using the OpenLCA 2.0.1 software, with data from the Ecoinvent 3.8 database and relevant literature. The assessment focused on multiple impact categories, including climate change, acidification, eutrophication (freshwater, marine and terrestrial), ecotoxicity (freshwater), human toxicity (cancer and non-cancer), ionizing radiation, land use, ozone depletion, photochemical ozone formation, resource use (fossils, minerals and metals), and water use. The LCA of a cosmetic cream containing gold nanoparticles revealed significant environmental impacts across critical categories. The total climate change potential was 2596.95 kg CO2 eq., driven primarily by nanoparticle synthesis (60.7%) and electricity use (31.9%). Eutrophication of freshwater had the highest normalized result (3.000), with nanoparticle synthesis contributing heavily, indicating the need for improved wastewater treatment. The resource use (minerals and metals) scored 1.856, while the freshwater ecotoxicity reached 80,317.23 CTUe, both driven by the nanoparticle production. The human toxicity potentials were 1.39 × 10−6 CTUh (cancer) and 7.45 × 10−5 CTUh (non-cancer), linked to emissions from synthesis and energy use. The LCA of the cosmetic cream revealed several critical areas of environmental impact. The most significant impacts are associated with gold nanoparticle synthesis and electricity use. Addressing these impacts through optimized synthesis processes, improved energy efficiency, and alternative materials can enhance the product’s sustainability profile significantly.
Keywords: life cycle assessment, cosmetic cream, environmental impacts, gold nanoparticles
Published in DKUM: 17.12.2024; Views: 0; Downloads: 9
.pdf Full text (1,71 MB)
This document has many files! More...

9.
Environmental factors influencing the distribution of habitat types in the highlands of the Kamnik - Savinja Alps
Sonja Škornik, Igor Paušič, Tone Novak, Franc Janžekovič, Danijel Ivajnšič, Mihaela Tostovršnik, Peter Kozel, 2021, original scientific article

Abstract: In this work, we investigated the relationship between habitat types (HTs) and selected environmental factors in the highlands at altitudes of 1800–2558 m in the Kamnik-Savinja (KS) Alps in Slovenia. For 275 sampling sites, we identified seven HTs in their typical form and 11 ecotones, and provided field and modelled data for 14 environmental factors. HTs-environment relationships were analysed using multivariate ordination methods. In addition, binomial generalised linear mixed models were applied to reveal the influence of environmental factors on the occurrence of most frequent HTs in the study area [Outer Alpine Pinus mugo scrub (EUNIS code F2.4/Natura 2000 code 4070*), Southern rusty sedge grasslands (E4.413/6170), Cushion sedge carpets (E4.433/6170) and Fine calcareous screes (H2.43/8120)]. Results showed that certain modelled data (e.g. average annual air temperature) combined with field measurements (e.g. inclination, soil surface and soil moisture) can be effective predictors of most representative HTs in the study area, and thus useful for further refining of monitoring. Our study contributes to the knowledge and understanding of the relationships between environmental conditions and the occurrence of highland HTs in KS Alps, which probably concerns a great part of the Alpine highlands. Such knowledge is essential for assessing credible long-term conservation planning.
Keywords: Alpine habitat types, multivariate analysis, Pinus mugo, alpine and subalpine calcareous grasslands, Natura 2000, Slovenia
Published in DKUM: 10.12.2024; Views: 0; Downloads: 4
.pdf Full text (2,18 MB)
This document has many files! More...

10.
Karakterizacija deformacijskega in mehanskega obnašanja avksetičnega kompozitnega metamateriala : diplomsko delo
Miha Kolar, 2024, undergraduate thesis

Abstract: Prispevek predlaga inovativen večmaterialen pristop za vpeljavo avksetičnega obnašanja v področje sintaktičnih pen. Z natančnim oblikovanjem velikosti, oblike in orientacije sintaktične pene je bilo doseženo avksetično deformacijsko obnašanje. Najprej so bili iz ekspandiranega perlita in mavca izdelani šestkotni elementi v obliki peščene ure, nato pa je bil avksetični vzorec teh elementov razporejen v škatlo iz nerjavnega jekla. Prazni prostori med vložki so bili zapolnjeni z aluminijevo zlitino (A356) s pomočjo uporabe tehnike proti gravitacijskega litja. Vliti avksetični kompozit je imel gostoto 1,52 g/cm3. Izdelan preizkušanec je bil nato deformiran s kvazi-statično obremenitvijo, da bi lahko okarakterizirali njegovo deformacijsko obnašanje in določili njegove mehanske lastnosti, zlasti Poissonovo število. Deformacija kompozita je bila avksetična s Poissonovim številom -1,04. Za boljše razumevanje mehanizma in zagotavljanje možnosti za nadaljnjo optimizacijo geometrije so bile izvedene računalniške simulacije po metodi končnih elementov.
Keywords: avksetične celične strukture, sintaktične pene, eksperimentalno testiranje, mehanske lastnosti, Poissonovo število
Published in DKUM: 06.12.2024; Views: 0; Downloads: 24
.pdf Full text (2,63 MB)

Search done in 0.31 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica