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53.
Mass composition of ultra-high energy cosmic rays at the Pierre Auger Observatory
Gašper Kukec Mezek, 2019, doktorska disertacija

Opis: Cosmic rays with energies above 10^18 eV, usually referred to as ultra-high energy cosmic rays (UHECR), have been a mystery from the moment they have been discovered. Although we have now more information on their extragalactic origin, their direct sources still remain hidden due to deviations caused by galactic magnetic fields. Another mystery, apart from their production sites, is their nature. Their mass composition, still uncertain at these energies, would give us a better understanding on their production, acceleration, propagation and capacity to produce extensive air showers in the Earth's atmosphere. Mass composition studies of UHECR try to determine their nature from the difference in development of their extensive air showers. In this work, observational parameters from the hybrid detection system of the Pierre Auger Observatory are used in a multivariate analysis to obtain the mass composition of UHECR. The multivariate analysis (MVA) approach combines a number of mass composition sensitive variables and tries to improve the separation between different UHECR particle masses. Simulated distributions of different primary particles are fitted to measured observable distributions in order to determine individual elemental fractions of the composition. When including observables from the surface detector, we find a discrepancy in the estimated mass composition between a mixed simulation sample and the Pierre Auger data. Our analysis results from the Pierre Auger data are to a great degree independent on hadronic interaction models. Although they differ at higher primary masses, the different models are more consistent, when combining fractions of oxygen and iron. Compared to previously published results, the systematic uncertainty from hadronic interaction models is roughly four times smaller. Our analysis reports a predominantly heavy composition of UHECR, with more than a 50% fraction of oxygen and iron at low energies. The composition is then becoming heavier with increasing energy, with a fraction of oxygen and iron above 80% at the highest energies.
Najdeno v: osebi
Ključne besede: astroparticle physics, ultra-high energy cosmic rays, extensive air showers, mass composition, Pierre Auger Observatory, machine learning, multivariate analysis
Objavljeno: 03.04.2019; Ogledov: 341; Prenosov: 24
.pdf Polno besedilo (17,53 MB)

54.
Vpliv toplotne obdelave na lastnosti orodnih jekel
Gašper Puš, 2015, diplomsko delo

Opis: Preoblikovalna orodja so izpostavljena istočasnemu delovanju termičnih, kemijskih, mehanskih in triboloških obremenitev. Kompleksna kombinacija obremenitev vodi do poškodbe orodja, kot so obraba, plastična deformacije ter utrujanje. Na splošno tip poškodbe zavisi od materiala in konstrukcije orodja, postopka preoblikovanja ter vrste preoblikovanega materiala. Največji vpliv pa ima material orodja in njegove lastnosti. Osnovna lastnost, ki okarakterizira orodje je trdota. V realnosti pa odpornost orodja zavisi od kombinacije lastnosti, kot so tlačna trdnost, upogibna trdnost, obdelovalnost in lomna žilavost. Lastnosti orodnih jekel zavisijo od njihove mikrostrukture, ki jo spreminjamo z ustrezno toplotno obdelavo. Seveda je za doseganje ustrezne kombinacije lastnosti potrebno natančno poznavanje vpliva toplotne obdelave na mikrostrukturo in lastnosti orodnih jekel. Namen diplomskega dela je določiti vpliv parametrov toplotne obdelave na mikrostrukturo in s tem na različne lastnosti orodnega jekla za delo v vročem, vključujoč trdoto, tlačno in upogibno trdnost, lomno žilavost ter obdelovalnost. V okviru diplomske naloge je bil uporabljen pristop določevanja mehanskih lastnosti z multifunkcijskim cilindričnim vzorcem z zarezo po obodu. S tem je bila omogočena direktna določitev korelacij med posameznimi lastnostmi orodnega jekla. Praktična vrednost diplomskega dela je v določitvi vpliva toplotne obdelave na različne lastnosti orodnega jekla za delo v vročem, predvsem pa v določitvi medsebojne korelacije med različnimi lastnostmi, ki omogočajo uporabnikom enostavnejšo in bolj natančno izbiro najustreznejše toplotne obdelave orodnega jekla za izbrano aplikacijo.
Najdeno v: osebi
Ključne besede: orodno jeklo, toplotna obdelava, lomna žilavost, trdnost, trdota, mikrostruktura
Objavljeno: 22.10.2015; Ogledov: 2508; Prenosov: 250
.pdf Polno besedilo (2,33 MB)

55.
Obrabna odpornost orodnega jekla za delo v vročem
Gašper Puš, 2018, magistrsko delo

Opis: Z vse bolj razširjeno uporabo visoko trdnih jekel pri izdelavi modernih komponent, predvsem v avtomobilski industriji, se povečuje tudi obremenitev preoblikovalnih orodij. Ta so izpostavljena kompleksnim obremenitvam kot so obraba, plastična deformacija in utrujanje, ki rezultirajo v nastanku poškodb in odpovedi orodja. Na splošno se kot osnovno lastnost karakterizacije orodja uporablja trdota, kar pa v zadnjem času ne zadošča. Potrebno je raziskovanje celotnega spektra mehanskih lastnosti, kakor tudi parametrov obrabne obstojnosti ter preoblikovalnosti. Preoblikovalna orodja so izpostavljena kombinaciji kompleksnih obremenitev. Da bi se ustrezno zoperstavili omenjenim obremenitvam in posledično z njimi nastalimi problemi, moramo poznati različne lastnosti materiala, vpliv legirnih elementov, proces toplotne obdelave in obnašanje materiala tekom le-te. Kljub temu, da je glavna mehanska lastnost trdota, pa na lastnosti preoblikovalnega orodja vplivajo še kombinacija tlačne in upogibne trdnosti ter lomne žilavosti, ki vplivajo na obrabno obstojnost, dobo trajanja orodja in njegovo vzdržljivost v industrijskem procesu.
Najdeno v: osebi
Ključne besede: orodno jeklo, toplotna obdelava, trdota, lomna žilavost, tlačna trdnost, upogibna trdnost, obraba, obrabna obstojnost, koeficient trenja
Objavljeno: 26.02.2018; Ogledov: 1176; Prenosov: 76
.pdf Polno besedilo (3,15 MB)

56.
Bottom-up modelling of continuous renovation and energy balance of existing building stock: case study Kočevje
Marjana Šijanec Zavrl, Gašper Stegnar, Andraž Rakušček, Henrik Gjerkeš, 2016, objavljeni znanstveni prispevek na konferenci

Opis: A dynamic bottom-up model of the building stock is developed and implemented in a case study of Kočevje urban region. In the model, national register of real estate is cross-linked to data from other registers, e.g. the energy performance certificates (EPC) and the subsidized energy renovation measures. Regular updates of the data in registers enable continual improvement of the model. Therenovation potential is determined with respect to the age of building components after the last renovation, while the energy performance of the building stock is based either on the EPC for a particular building if available or on the energy indicators of corresponding building type from IEE EPISCOPE building typology and IEE RePublic_ZEB. Thus, the bottom-up model of the building stock (BuilS) enable a profound overview of the total heat demand, final energy use and CO2 emissions of the entire stock. In the case study Kočevje, various strategies for improving the buildings towards more sustainable ones are presented with projections to 2030. The strategies, reference and intensive renovation scenario, are compared with more ambitious strategy that the municipality is looking towards in the frame of Covenant of Mayors commitment. The bottom-up model was validated against the metered energy use of buildings connected to district heating. In the case study the model shows how the implementation of various strategies lead to different impacts and how the ambitious municipal plans are going to produce independence from fossil fuels by fostering the use of wood biomass as a locally available sustainable energy supply. The Kočevje case study analysis demonstrates, at the local level how a concept of increasing renewable energy sources utilisation and building energy efficiency stimulated by progressive measures can respond to low carbon society and sustainable energy selfsupply challenges.
Najdeno v: osebi
Ključne besede: modelling, renovation scenarios, building stock, region policies
Objavljeno: 12.04.2016; Ogledov: 1481; Prenosov: 0
.pdf Polno besedilo (19,51 MB)

57.
Spremljanje delovanja napredno načrtovane skoraj nič-energijske večstanovanjske stavbe
Gašper Stegnar, Miha Mirtič, Henrik Gjerkeš, Marjana Šijanec Zavrl, 2016, objavljeni znanstveni prispevek na konferenci

Opis: Učinkovita raba energije in intenzivnejše izkoriščanje obnovljivih virov energije tudi v stanovanjskem sektorju zahteva sodobne pristope k naprednemu načrtovanju stavb ob hkratni skrbi za ustrezno bivalno ugodje v njih. Nacionalna merila za skoraj nič-energijske stavbe (sNES), ki bodo postala obvezna l. 2020, smo uporabili kot izhodišče za načrtovanje Eko srebrne hiše, večstanovanjske stavbe s 128 stanovanji, ki je bila kot FP7 EE-Highrise demonstracijski projekt l. 2015 zgrajena v Ljubljani. Načrtovanje in gradnja sta potekala z naprednimi orodji za dinamično simulacijo na urni osnovi z realnimi robnimi pogoji, s sprotnim spremljanjem kakovosti, kontrolo zrakotesnosti, spremljanjem rabe energije in parametrov bivalnega ugodja. Primerjava projektiranih in izmerjenih ključnih parametrov v izbranih naseljenih in še nenaseljenih stanovanjih pokaže učinkovitost naprednih orodij za načrtovanje stavb, pri čemer podrobnejša analiza izlušči tudi vzroke za nekatera odstopanja.
Najdeno v: osebi
Ključne besede: Skoraj nič-energijske stavbe, dinamični model, toplotni odziv stavbe, bivalno ugodje
Objavljeno: 26.04.2016; Ogledov: 1736; Prenosov: 137
.pdf Polno besedilo (950,18 KB)

58.
A Bottom-Up Building Stock Model for Tracking Regional Energy Targets—A Case Study of Kočevje
Marjana Šijanec-Zavrl, Gašper Stegnar, Andraž Rakušček, Henrik Gjerkeš, 2016, izvirni znanstveni članek

Opis: The paper addresses the development of a bottom-up building stock energy model (BuilS) for identification of the building stock renovation potential by considering energy performance of individual buildings through cross-linked data from various public available databases. The model enables integration of various EE and RES measures on the building stock to demonstrate long-term economic and environmental effects of different building stock refurbishment strategies. In the presented case study, the BuilS model was applied in the Kočevje city area and validated using the measured energy consumption of the buildings connected to the city district heating system. Three strategies for improving the building stock in Kočevje towards a more sustainable one are presented with their impact on energy use and CO2 emission projections up to 2030. It is demonstrated that the BuilS bottom-up model enables the setting of a correct baseline regarding energy use of the existing building stock and that such a model is a powerful tool for design and validation of the building stock renovation strategies. It is also shown that the accuracy of the model depends on available information on local resources and local needs, therefore acceleration of the building stock monitoring on the level of each building and continually upgrading of databases with building renovation information is of the utmost importance.
Najdeno v: osebi
Ključne besede: bottom-up modelling, renovation scenarios, building stock, regional energy policy
Objavljeno: 25.10.2016; Ogledov: 1154; Prenosov: 121
.pdf Polno besedilo (5,27 MB)

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