Optimization of Excitation in FDTD Method and Corresponding Source Modeling

Source and excitation modeling in FDTD formulation has a significant impact on the method performance and the required simulation time. Since the abrupt source introduction yields intensive numerical variations in whole computational domain, a generally accepted solution is to slowly introduce the source, using appropriate shaping functions in time. The main goal of the optimization presented in this paper is to find balance between two opposite demands: minimal required computation time and acceptable degradation of simulation performance. Reducing the time necessary for source activation and deactivation is an important issue, especially in design of microwave structures, when the simulation is intensively repeated in the process of device parameter optimization. Here proposed optimized source models are realized and tested within an own developed FDTD simulation environment

Simulations of cosmic reionization

In this thesis we investigate numerically how ionizing photons emitted by stars in galaxies cause the reionization of the Universe, the transition during which most of the gas in the Universe from a mostly neutral, to a highly ionised state it is in today. To this end, we discuss and improve two techniques for the transport of ionising radiation across cosmological volumes, analyse the sources of ionising photons at high redshifts predicted by a semi-analytical galaxy formation model (GALFORM), and combine these to make consistent model of how reionization proceeds. Our improvements to the hybrid characteristics (HC) radiative transport scheme are significant, making the code faster and more accurate, as demonstrated by our contribution to a code comparison paper (Iliev et al., 2009). Our improvements to the SimpleX radiative transport scheme allow for accurate and significantly better numerically converged calculations of the speeds of ionization fronts of cosmological HII regions. This is accomplished by a much more thorough analysis of how to properly model the density field on the unstructured density field in SimpleX. The dependence of the ionizing emissivity of GALFORM galaxies on various parameters of the model is examined. We show that massive stars formed in abundance because of the assumed top-heavy stellar initial mass function during starbursts in the Baugh et al. (2005) model, triggered by galaxy mergers, are the dominant source of ionizing photons. We show that the luminosity functions predicted by this model are in good agreement with the most recent Hubble Space Telescope results at z \gtrsim 8. The model also demonstrates that most photons are produced in faint galaxies which are not yet seen in the current data. We then combine the sources predicted by GALFORM with the SimpleX RT scheme to model inhomogeneous reionization including the effects of source suppression. We investigate how the morphology of reionization depends on the model for the sources, which may be crucial for future observations of this cosmic epoch

Stanje specijalnog rezervata prirode “Ludaško jezero” sa bakteriološkog aspekta

U ovom radu su prikazani rezultati bakteriološkog ispitivanja vode i sedimenta severnog i južnog dela jezera Ludaš. Jezero Ludaš je deo parka prirode Palić-Ludaš, a zbog velikog značaja u očuvanju ornitološkog diverziteta ovog područja od 1977. godine je zaštićeno i Ramsarskom konvencijom. Uzorci su sakupljani od novembra 2013. do marta 2015. godine i ukupno je analizirano 10 uzoraka vode i sedimenta. Kvalitet vode je ocenjen na osnovu ukupnog broja heterotrofnih bakterija (mezofila i psihrofila), fakultativnih oligotrofa, ukupnog broja koliformnih i fekalnih koliformnih bakterija, broja E.coli i fekalnih enterokoka. Ocenjivanje je izvršeno prema ekološkom i sanitarnom kriterijumu koristeći kriterijume Uredbe o kvalitetu površinskih voda i sedimenta Republike Srbije. Rezultati ukazuju na veliko variranje mikrobnog diverziteta tokom ispitivanog perioda. Na osnovu ukupnog broja bakterija, voda se može svrstati u II - IV klasu voda na severnoj strani, dok je na južnom delu voda u kategoriji III - V klase kvaliteta. Međutim, na osnovu indikatora fekalnog zagađenja, voda jezera na južnoj strani je značajno boljeg kvaliteta i u većini merenja odgovara kvalitetu I i II klase vodotoka. Razlike u sastavu saprofitne i potencijalno patogene grupe mikroorganizama zastupljene u različitim delovima jezera se mogu objasniti geografskim karakteristikama i vodi koja se kanalom Palić-Ludaš uliva u severni deo jezera, što utiče na broj bakterija indikatora fekalnog zagađenja. Veliko organsko opterećenje u južnom delu jezera se ogleda u značajno većem broju saprofitnih heterotrofa, a manjem autohtonih oligotrofa čime se smanjuje sposobnost autopurifikacije vode i ukazuje na ekološku ugroženost i ubrzan process eutrofikacije jezera Ludaš

THE INFLUENCE OF VARIETY AND VINTAGE ON THE CHEMICAL COMPOSITION AND SENSORY PROPERTIES OF RED WINES IN PODGORICA SUBREGION (MONTENEGRO)

This paper presents the results of investigation of the influence of variety and vintage on the chemical composition and sensory properties of Vranac, Kratosija and Cabernet Sauvignon wines in Podgorica subregion (Montenegro) in vintages 2012 and 2013. The varietal wines were produced from the grapes grown at four different localities, according to a uniform manner (traditional method) in the winery of the Biotechnical Faculty, located at the experimental farm in Podgorica, at the vineyard location of Ljeskopolje. The analysis of basic chemical parameters of wines and sensorial testing of wines were carried out. The research findings show that variety and vintage (climatic conditions) significantly affected the chemical composition of wine. The higher content of alcohol and extract was measured in 2012 vintage, while the total acid content in wine was higher in2013, as a result of frequent rainfall during the growing season, especially in August and September. The highest content of alcohol, extracts and total acids was found in Kratosija wine, then in Cabernet Sauvignon, while the lowest content was found in Vranac wine in both vintages. According to sensory properties and average testing score for the two years of research, all wines fall into the category of superior wines

The evolution of the eutrophication of the Palić Lake (Serbia)

Eutrophication is a world-wide environmental issue. The Palic Lake is a shallow lake typical for the Pannonian plain. The Lake itself was in a very bad condition during the late sixties of the last century; polluted and hypertrophic. Due to inadequate water quality, it was dried out in 1971 and re-established in 1977 and since then its trophicity has been worsening. The lake has recreational purposes but it is also a collector for treated municipal waste waters coming from the lagoons for active sludge water treatment. The sewage discharges from rapidly developing towns in the watershed and the growing use of fertilizers in agriculture increased the nutrient load to the Lake in the last decades. A steady increase of phosphorus loading is the most important factor of the lake  eutrophication. The result of the accelerated eutrophication is the enormous amount of sediment at the bottom of the Palic Lake. Therefore, in the lake that covers an area of 565 ha and volume of 10 million m3, there was 1.900.160 m3 of sediment. The sediment thickness varied from 0.3 to 1.2 m. In summer 2010, the recreational part of the lake (sector IV) was 1.311.356 m3 of sediment, characterized with concentrations of total phosphorus (TP) of 2885 mg/kg, 4300 mg/kg total nitrogen (TN) and 39000 mg/kg total organic carbon TOC. The sediment of the Palic Lake was not loaded with high concentrations of heavy metals. Everything mentioned supports the fact that the restoration of this aquatic system is necessary and applied measures have to be grounded on the principles of ecoremediation technologies.Key words: Eutrophication, Palic Lake, sediment, total N, total P

Language attitudes towards Serbian Sign Language and experiences with deaf education in Serbia

In this paper, we report on data obtained from interviews with 28 deaf signers and three hearing teachers of deaf pupils regarding their experiences with and attitudes towards deaf education and Serbian Sign Language (SZJ). Following transcription of the data, we conducted thematic analyses of the deaf informants’ and teachers’ comments. Data, which indicate that a change in language attitudes among deaf people has taken place compared to the oralist ideology still prevalent among teachers, are considered within a broader historical context by giving the first account of SZJ, its place in education and its history. In the light of the results, we highlight the importance of teacher training for promoting a cultural-linguistic minority perspective in deaf education in Serbia that would allow for deafness to be viewed as human diversity rather than disability