101. Detection of gravitational waves : Diploma thesisGregor Mrak, 2016, diplomsko delo Opis: This report mainly focuses on the first two detections of gravitational waves
(GW). At the beginning of the thesis the historical background of GW explorations
is discussed by pointing out some arguments and researchers
that were essential for the progress. Continuing with the derivation based
on the theory of general relativity, in order to express where certain properties
derive. In the main part of the report, the subject of interest becomes
Laser interferometer gravitational-wave observatory (LIGO), beginning
with the problems occurring on the way to detection, describing different
noise sources one by one. After pointing out the problems, solutions
are discussed, namely the technological advances made to lower the background
noise as much as possible. The chapter (4) points out different parts
of the detector which are implemented to produce a clearer signal. As only
physical noise reduction methods are not enough, digital signal processing
algorithms are mentioned as well which are used to analyze the data. Subsequently
the required theoretical knowledge is given, so the main part ends
with the analysis of actual data taken from LIGO’s public release for both
GW150914 and GW151226 events (first and second official detections). In
the conclusion of the report a brief descriptions of various detectors besides
Ligo are given and some insight of the future detectors that are planned to
be built. Ključne besede: Gravitational waves, Ligo, Binary black hole merger, gravitational
wave interferometry Objavljeno v RUNG: 27.09.2016; Ogledov: 7110; Prenosov: 317 Celotno besedilo (3,27 MB) |
102. Atomically resolved dealloying of structurally ordered Pt nanoalloy as an oxygen reduction reaction electrocatalystAndraž Pavlišič, Primož Jovanovič, Vid Simon Šelih, Martin Šala, Marjan Bele, Goran Dražić, Iztok Arčon, Samo B. Hočevar, Anton Kokalj, Nejc Hodnik, Miran Gaberšček, izvirni znanstveni članek Opis: The positive effect of intermetallic ordering of platinum alloy nanoparticles on oxygen reduction reaction (ORR) activity has been well established. What is still missing is an understanding of selective leaching of the less noble metal from the ordered structure and its correlation to longterm ORR performance. Using a combination of kinetic Monte Carlo simulations and advanced characterization techniques, we provide unprecedented insight into dealloying of intermetallic PtCu3 nanoparticles a well-known binary alloy. Comparison of ordered and disordered samples with identical initial compositions and particle size distributions reveals an unexpected correlation: whereas the copper dealloying rates in the ordered and disordered counterparts are almost the same, in the ordered structure Pt atoms are surrounded by 15−30% more Cu atoms throughout all the stages of acid leaching. This more convenient Pt−Cu coordination explains the statistically significant increase of 23−37% in ORR activity of the ordered structure at all stages of alloy degradation. Ključne besede: ORR activity, fuel cells, platinum alloy, nanoparticle stability, intermetallic ordering, kinetic Monte Carlo, dealloying, in situ ICP-MS Objavljeno v RUNG: 27.09.2016; Ogledov: 5704; Prenosov: 0 Gradivo ima več datotek! Več... |
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104. Encapsulation efficiency of CdSe/ZnS quantum dots by liposomes determined by thermal lens microscopyDorota Korte, Jessica Batalla, Humberto Cabrera, Eduardo San Martín-Martínez, Antonio Calderón, Ernesto Marín Moares, 2015, izvirni znanstveni članek Ključne besede: microscopy, imaging systems, thermal lensing, medical imaging, biological imaging, cell analysis Objavljeno v RUNG: 17.05.2016; Ogledov: 4509; Prenosov: 143 Povezava na celotno besedilo |
105. Ge(2), Ge(1) and Ge-E´ centers in irradiated Ge-doped silica : a first-principles EPR studyLayla Martin-Samos, Nicolas Richard, Sylvain Girard, A. Boukenter, Youcef Ouerdane, Luigi Giacomazzi, 2015, izvirni znanstveni članek Ključne besede: silica, density-functional theory, defects Objavljeno v RUNG: 17.05.2016; Ogledov: 4854; Prenosov: 123 Povezava na celotno besedilo |
106. Properties of Null HypersurfacesHovhannes Demirtshyan, 2016, magistrsko delo Opis: The aim of this thesis is to investigate the effects that a lightlike singular hypersurface can have on a congruence of timelike (spacelike) geodesics and to extend the existing theory to the case of null geodesics.
The introduction discusses the applications of singular hypersurfaces for the description of physical phenomena, their major classfications and includes a short discussion of the two theoretical approaches that exist to study singular hypersurfaces. The second chapter contains detailed description of these approaches. The theoretical frameworks for both cases of lightlike and timelike (spacelike) hypersurfaces are developed. This chapter also discusses the application of these theories to the case when the hypersurface contains a plane fronted lightlike signal.
The final chapter starts with a discussion of the effects that a lightlike singular hypersurface can have on a congruence of timelike (spacelike) geodesics. A new approach to these calculations is presented together with an extension of the theory to the case of a congruence of null geodesics. At
the end of the chapter a concrete example and its similarities with the case of timelike geodesics is discussed.
In conclusion, the thesis suggests a new mathematical framework for describing a congruence of null geodesics crossing a singular null hypersurface. The results may be applied in experimental physics to detect impulsive signals which are located in singular null hypersurfaces and to this end there
is a discussion of the properties and possibilities for a detector of impulsive lightlike signals, which include gravitational waves. Ključne besede: singular hypersurface, impulsive signal, gravitational wave, null geodesic, timelike (spacelike) geodesic Objavljeno v RUNG: 16.05.2016; Ogledov: 7595; Prenosov: 261 Celotno besedilo (475,54 KB) |
107. Gamma and x-ray irradiation effects on different Ge and Ge/F doped optical fibersAntonino Alessi, Sylvain Girard, Imene Reghioua, Mattia Fanetti, Diego Di Francesca, Simonpietro Agnello, Marco Cannas, Claude Marcandella, Layla Martin-Samos, N. Richard, Aziz Boukenter, Youcef Ouerdane, 2015, izvirni znanstveni članek Ključne besede: optical fibers, Germanium, doping, cathodoluminescence, irradiation effect Objavljeno v RUNG: 11.04.2016; Ogledov: 5711; Prenosov: 0 Gradivo ima več datotek! Več... |
108. Horizon Shells and BMS-like soldering transformationsMatthias Blau, Martin O'Loughlin, 2016, izvirni znanstveni članek Opis: We revisit the theory of null shells in general relativity, with a particular
emphasis on null shells placed at horizons of black holes. We study in detail the considerable
freedom that is available in the case that one solders two metrics together across null
hypersurfaces (such as Killing horizons) for which the induced metric is invariant under
translations along the null generators. In this case the group of soldering transformations
turns out to be infinite dimensional, and these solderings create non-trivial horizon shells
containing both massless matter and impulsive gravitational wave components. We also
rephrase this result in the language of Carrollian symmetry groups. To illustrate this
phenomenon we discuss in detail the example of shells on the horizon of the Schwarzschild
black hole (with equal interior and exterior mass), uncovering a rich classical structure
at the horizon and deriving an explicit expression for the general horizon shell energy-
momentum tensor. In the special case of BMS-like soldering supertranslations we find a
conserved shell-energy that is strikingly similar to the standard expression for asymptotic
BMS supertranslation charges, suggesting a direct relation between the physical properties
of these horizon shells and the recently proposed BMS supertranslation hair of a black hole. Ključne besede: Black Holes, Classical Theories of Gravity, Space-Time Symmetries Objavljeno v RUNG: 10.03.2016; Ogledov: 4765; Prenosov: 0 Gradivo ima več datotek! Več... |
109. Sistem za verzioniranje dokumentovMartin Lozar, 2016, magistrsko delo Opis: Glavna cilja magistrske naloge sta pregled obstoječih sistemov za verzioniranje podatkov in njihovih funkcionalnosti ter izdelava lastne spletne aplikacije – sistema za verzioniranje dokumentov. Verzioniranje dokumentov je postopek hranjenja dokumenta in vseh njegovih sprememb, ki so se nad dokumentom zgodile skozi čas. Za potrebe izdelave spletne aplikacije, ki jo uporabniki poganjajo znotraj spletnega brskalnika, smo najprej zgradili podatkovni model. Le tega smo nato implementirali znotraj relacijske podatkovne baze PostgreSQL, v kateri se hranijo podatki, potrebni za delovanje spletne aplikacije. Razvita spletna aplikacija DRS omogoča izdelavo poljubne podatkovne datotečne strukture – poljubna hierarhija map s pripadajočimi dokumenti. Registriranim uporabnikom omogoča dodeljevanje različnih dostopnih pravic na posamezni mapi, omejitev tipa datotek, ki jih uporabniki lahko shranjujejo znotraj aplikacije, in verzioniranje dokumentov. Uporabniki lahko dokumente znotraj izbrane mape pregledujejo v dveh različnih načinih. V drugem poglavju opisujemo nekaj aplikacij, ki uporabljajo sisteme za verzioniranje podatkov, tretje poglavje predstavlja motivacijo za izdelavo aplikacije in opiše ter predstavi funkcionalnosti in ideje, ki jih DRS podpira, naslednje, četrto poglavje pa na kratko predstavlja delovanje spletnih aplikacij. Peto poglavje predstavi tehnologije, ki smo jih uporabili za razvoj DRS, šesto poglavje opisuje splošno delovanje DRS s predstavitvijo sistemskih zahtev, ki jih aplikacija potrebuje za delovanje, v sedmem poglavju opisujemo delovanje DRS in podajamo nekaj primerov uporabe. Sledi zadnje poglavje, v katerem predstavljamo razloge za odločitev določenega načina implementacije dela funkcionalnosti DRS. V zaključku povzamemo vsebino magistrske naloge in podajamo nekaj možnih izboljšav razvite spletne aplikacije. Ključne besede: sistem za verzioniranje dokumentov, spletna aplikacija, PHP, PostgreSQL, JSON, jQuery Objavljeno v RUNG: 21.01.2016; Ogledov: 6848; Prenosov: 296 Celotno besedilo (1,86 MB) Gradivo ima več datotek! Več... |
110. Strateško načrtovanje v dejavnosti turizma in gostinstva: študija primera turistične destinacije v izbrani mestni občiniMartin Bizjak, 2015, magistrsko delo Opis: V magistrskem delu obravnavamo problematiko strateškega managementa v izbrani turistični destinaciji, ker smo na področju raziskovanja in predhodnega preučevanja omenjene problematike identificirali raziskovalno vrzel. Namen magistrskega dela je, na podlagi sistematičnega pregleda domače in tuje strokovne literature ter zasnovi konceptualnega modela strategije razvoja turizma, empirično preveriti stopnjo razvitosti strateškega načrtovanja turistične in gostinske dejavnosti v izbrani turistični destinaciji ter podati morebitne predloge za izboljšanje stanja.
Za empirični del raziskave smo uporabili kvalitativno metodo raziskovanja in oblikovali raziskovalna vprašanja ter nato opravili intervju s štirimi predstavniki turističnih ponudnikov in tremi predstavniki organizacij, ki so vpete v lokalni turizem. Ugotovili smo, da tako konkurenčne prednosti kot družbena odgovornost in vrednote statistično značilno vplivajo na uspešnost turističnega podjetja. Izidi iz raziskave predstavljajo prispevek k širšemu vpogledu na strateški management v turizmu ter bodo uporabni za vse tiste, ki se teoretično, raziskovalno ali strokovno ukvarjajo s to dejavnostjo. Ključne besede: Management, organizacija, raziskava, strateški management, turistična destinacija Objavljeno v RUNG: 29.09.2015; Ogledov: 6686; Prenosov: 461 Celotno besedilo (1,06 MB) |