Mathematical and physical modeling of flow in rivers with floodplains

This doctoral thesis discusses various approaches to modeling flow in rivers with floodplains. Measurements on a physical hydraulic model of the Sava River with distinctive floodplains provided noteworthy data which were used for a detailed numerical analysis of the flow interaction between the main channel and floodplains. Turbulence models incorporated into the mathematical model PCFLOW2D, which was developed more than two decades ago and is continuously being improved at the Chair of Fluid Mechanics with Laboratory, Faculty of Civil and Geodetic Engineering, University of Ljubljana, were precisely analyzed and modified. By analyzing the impact of a single term in a\ud momentum two-dimensional time-averaged Navier-Stokes (Reynolds) equation, which describes the depth-averaged flow, it has been shown that in cases of flows in large water bodies, use of an appropriate turbulence model does not play an essential role because the influence of turbulence can be sufficiently covered through the friction term. Therefore the flow in a vertical slot fishway, where\ud turbulence is very pronounced and its accurate modeling is of great importance was investigated. For this particular case, the sensitivity analysis was carried out for the recently integrated Smagorinsky turbulence model. Analysis has shown that, in order to achieve good agreement of numerical results with measurements, it is necessary to calibrate the Smagorinsky coefficient Cs. This is a new\ud discovery, as to our knowledge all previous studies and other numerical programs recommended an equal value (or within a very small interval) of the coefficient Cs for all types of flow. Our analysis showed that the value of the coefficient Cs is highly dependent on the applied numerical grid and individual type of flow and can significantly deviate from the previous reference values. With the detailed sensitivity analysis of parameters of the mathematical model, progress has been made in understanding the issues addressed, which should in the future allow easier and faster calibration of mathematical models and greater confidence in the obtained results

Poboljšavanje svojstava brzoreznog čelika 1.3302u vrućem stanju

Laboratory investigation of hot workability of 1.3302 high speed steel was carried out and its improving was achieved. Hot compression tests for the determination of optimal soaking temperature as well as for the study of hot workability in temperature range 1150-850 ºC, strain rates range 0,001-6 s–1 and applied strain up to 0,9 were performed. Microstructure of deformed specimen was analyzed. Apparent activation energies for hot working for upper and for lower temperature range were calculated. Onsets of dynamical recrystallization for applied deformation conditions on the basis of calculated strain hardening ratewere determined. Extending of hot working temperature range at its lower limit, i.e. down to 850 ºC, by applying optimal soaking temperature was obtained.Data su laboratorijska istraživanja prerađivačkih svojstva brzoreznog čelika 1.3302 u vrućem stanju koji su doprinijeli poboljšanju tih svojstava. Izvedeni su pokusi vrućeg sabijanja za određivanje temperature zagrijavanja kao i prerađivačkih svojstva u temperaturnom rasponu 1 150-850 ºC, brzinom deformacije 0,001-6 s–1 i stupnja deformacije do 0,9. Analizirana je mikrostruktura deformiranih proba.Izračunane su prividne aktivacijske energije za vruću preradu za gornje i donje temperaturno područje. Počeci dinamičke rekristalizacije za primijenjene uvjete deformacije utvrđeni su na temelju izračuna brzine deformacijskog očvršćavanja. Primjenjujući optimalno temperaturu zagrijavanja dobiveno je povećanje vrućeg radnog temperaturnog raspona na svojoj donjoj granici, odnosno do 850 ºC

Increasing of hot workability of 1.3302HIGH speed steel

Laboratory investigation of hot workability of 1.3302 high speed steel was carried out and its improving was achieved. Hot compression tests for the determination of optimal soaking temperature as well as for the study of hot workability in temperature range 1150-850 ºC, strain rates range 0,001-6 s<sup>–1/sup> and applied strain up to 0,9 were performed. Microstructure of deformed specimen was analyzed. Apparent activation energies for hot working for upper and for lower temperature range were calculated. Onsets of dynamical recrystallization for applied deformation conditions on the basis of calculated strain hardening ratewere determined. Extending of hot working temperature range at its lower limit, i.e. down to 850 ºC, by applying optimal soaking temperature was obtained

Mechanisms of Oxidation Degradation of Cr12 Roller Steel during Thermal Fatigue Tests

Degradation by the penetration of oxidation into the Cr12 roller steel is evaluated during thermal fatigue tests in the laboratory in the temperature range of 500–700 °C. A qualitative assessment is carried out with regard to the thermal load, the microstructure and the test temperature. The results show that the specific properties of the microstructure with respect to thermal stress and temperature have a significant influence on the oxidation behavior as well as on the crack propagation mode and crack growth. The conditions that lead to an increase in the oxidation rate and thus to premature and sudden local chipping of the roll surface layer are analyzed and explained.</jats:p

Perinatal outcomes of pregnant refugees/asylum seekers in Slovenia during the 2015–2016 humanitarian corridor

Introduction. During 2015 and 2016, a large number of refugees, including women, travelling along the so-called Balkan route crossed Slovenia. Studies increasingly show that women who migrate have different perinatal health outcomes compared to citizens. Aim. To review perinatal outcomes in pregnant refugees/asylum seekers giving birth in Slovenia during the 2015–2016 “humanitarian corridor”. Methods. Questionnaires on numbers of pregnant refugees/asylum seekers giving birth in Slovenia during 2015–2016, their perinatal outcomes and their perinatal care were sent to state institutions (Ministry of Health, Ministry of Internal Affairs, and National Institute for Public Health) and all 14 country’s maternity hospitals. Results. Data on perinatal outcomes in refugees/asylum seekers were available only at maternity hospitals, suggesting there is no national governmental system for collecting information on health of pregnant refugees/asylum seekers in Slovenia. Twelve refugees/asylum seekers who delivered in Slovenia during the “humanitarian corridor” in 2015–2016 were identified. Three (25%) of these deliveries were preterm births (<37 weeks of gestation). There were two (16%) emergency cesarean deliveries and no stillbirths or neonatal deaths. Average neonatal birth weight was 3130 g. Discussion. A very high (25%) preterm birth rate and a high emergency cesarean rate (16%) in the population of refugees/asylum seekers delivering in Slovenia during 2015–2016 “humanitarian corridor” was found. This study also identified several inadequacies in perinatal data collection in pregnant refugees/asylum seekers in Slovenia. Conclusions. Given the potentially higher incidence of perinatal complications, such as preterm birth or need for emergency cesarean delivery, seen in the present study, it is important to develop systems of data collection in pregnant refugees/asylum seekers

Problemi kod reparaturnog zavarivanja alatnog čelika sa duplex zaštitom

The present paper addresses problems in laser welding of die-cast tools used for aluminum pressure die-castings and plastic moulds. To extend life cycle of tools various surface improvements are used. These surface improvements significantly reduce weldability of the material. This paper presents development of defects in repair welding of duplex-treated tool steel. The procedure is aimed at reduction of defects by the newly developed repair laser welding techniques. Effects of different repair welding process parameters and techniques are considered. A microstructural analysis is conducted to detect defect formation and reveal the best laser welding method for duplex-treated tools.U radu su istraženi problemi kod laserskog zavarivanja alata za lijevanje u industriji tlačnog lijeva aluminija ili plastike. Za produženje života alata primjenjena su različita poboljšanja površine. Ovakva poboljšanja značajno smanjaju sposobnost materijala za zavarivanje. U radu se opisuje razvoj grešaka kod reparaturog zavarivanja alatnog čelika sa dupleks zaštitom. Nametnuta procedura nastoji smanjiti greške sa novom zavarivnom tehnikom. Proučeni su I efekti različitih parametra procesa i tehnika zavarivanja. Mikrostrukturnim istraživanjima nastoju se naći greške za odabir najboljeg postupka za lasersko zavarivanje alata za dupleks zaštitom

Key theories of metaphor in the history of philosophy and linguistics

V tej nalogi bom predstavil glavne teorije metafore v zgodovini jezikoslovja in filozofije. Najprej bom predstavil nekaj sodobnih definicij metafore kot besedne figure, nato pa pretehtal, če takšna teorija metafore zares sledi Aristotelovi osnovni ideji. V osrednjem tretjem poglavju bom predstavil Aristotelove štiri tipe metafore, na podlagi teh štirih tipov pa bom kritično predstavil še tri glavne vidike metafore: substitucijskega, primerjalnega in interakcijskega. Četrto poglavje bo služilo orisu teh vidikov in vzpostavitvi osi razlike med bolj konceptualnimi in bolj pragmatičnimi teorijami. V petem poglavju se bom posvetil poglavitno sodobnim kognitivnim in pragmatičnim teorijam metafore. Najprej bom predstavil konceptualno teorijo, potem pa na podlagi treh kritik te teorije izpostavil še tri druge: teorijo primarne metafore, teorijo konceptualnega mešanja ter teorijo relevantnosti. Med drugim se bom spraševal tudi o tem, ali so te tri teorije s konceptualno teorijo združljive, ali pa ji nasprotujejo.In this present thesis, I will deal with some of the main theories of metaphor within the context of history of lingustics and philosophy. First I will present some classical definitions of metaphor as a figure of speech. I will also question the proposition that classical theory stems from Aristotle\u27s thought. In the central third chapter I will present Aristotle\u27s four types of metaphor. On the basis of these four types, I will point out three main aspects of metaphor theories: substitution, comparison and interaction. In the fourth chapter, I will try to illustrate these, as well as establish a differential axis upon the basis of which we will later be able to articulate the main differences between cognitive and pragmatic theories. In the fifth and last chapter, I will deal with these. I will first present conceptual metaphor theory and mention some of its critiques. These critiques will carry us into a space of possible resolve, where I will present some other theories: primary metaphor theory, conceptual blending theory and relevance theory. Among other things, I will also question the supposed incompatibility of these theories