Promene stanovništva Srbije u postjugoslovenskom periodu (1991–2017): važniji demografski aspekti / The Population Change in Serbia in the Post-Yugoslav Period (1991-2017): Significant Demographic Aspects

Cilj rada je da se razmatraju trendovi kretanja stanovništva Srbije i njegovih komponenti tokom poslednje tri decenije. To je period korenitih političkih, ekonomskih i socijalnih transformacija. Analiza je zasnovana na podacima vitalne statistike (1991–2017), popisa iz 1991, 2002. i 2011, kao i zvaničnih ili procena autora. U tom periodu neki raniji dugoročni procesi su nastavljeni (pad fertiliteta, snižavanje mortaliteta, iseljavanje), ali su prisutne i neke nove pojave i procesi (smanjenje stanovništva, negativan prirodni priraštaj, masovne prisilne migracije). Autori ukazuju na međuzavisnost analiziranih promena komponenti demografskog rasta i odmaklog starenja stanovništva i zaključuju da su to najvažniji činioci koji će odlučujuće delovati na demografski razvitak Srbije u narednim decenijama

Adaptive intelligence applied to numerical optimisation

The article presents modification strategies theoretical comparison and experimental results achieved by adaptive heuristics applied to numerical optimisation of several non-constraint test functions. The aims of the study are to identify and compare how adaptive search heuristics behave within heterogeneous search space without retuning of the search parameters. The achieved results are summarised and analysed, which could be used for comparison to other methods and further investigation

Analysis of Hybrid Hydrogen Systems: Final Report

This project examined biomass pathways for hydrogen production and how they can be hybridized to support renewable electricity generation. The project considered many potential hybrid systems before narrowing the focus to two. The systems were studied in detail for process feasibility and economic performance. The best-performing system was estimated to produce hydrogen at a cost ($1.67/kg) within range of the Department of Energy target for central biomass-derived hydrogen production, while also providing value-added energy services to the electric grid

The 3d-to-4s-by-2p highway to superconductivity in cuprates

High-temperature superconductors are nowadays found in great variety and hold technological promise. It is still an unsolved mystery that the critical temperature T_c of the basic cuprates is so high. The answer might well be hidden in a conventional corner of theoretical physics, overlooked in the recent hunt for exotic explanations of new effects in these materials. A forgotten intra-atomic s-d two-electron exchange in the Cu atom is found to provide a strong (~eV) electron pairing interaction. A Bardeen-Cooper-Schrieffer approach can explain the main experimental observations and predict the correct d_{x^2-y^2} symmetry of the gap.Comment: 4 pages, 3 figures, LaTeX2

The role of electronic correlation in the Si(100) reconstruction: a quantum Monte Carlo study

Recent low-temperature scanning tunneling experiments have challenged the generally accepted picture of buckled silicon dimers as the ground state reconstruction of the Si(100) surface. Together with the symmetric dimer model of the surface suggested by quantum chemistry calculations on small clusters, these findings question our general understanding of electronic correlations at surfaces and its proper description within density functional theory. We present quantum Monte Carlo calculations on large cluster models of the symmetric and buckled surface, and conclude that buckling remains energetically more favorable even when the present-day best treatment of electronic correlation is employed.Comment: 5 pages, Revtex, 10 figure

The Mass-Radius Relationship for Very Low Mass Stars: Four New Discoveries from the HATSouth Survey

We report the discovery of four transiting F-M binary systems with companions between 0.1-0.2 Msun in mass by the HATSouth survey. These systems have been characterised via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters, and equating spectroscopic primary star rotation velocity with spin-orbit synchronisation. These new very low mass companions are HATS550-016B (0.110 -0.006/+0.005 Msun, 0.147 -0.004/+0.003 Rsun), HATS551-019B (0.17 -0.01/+0.01 Msun, 0.18 -0.01/+0.01 Rsun), HATS551-021B (0.132 -0.005/+0.014 Msun, 0.154 -0.008/+0.006 Rsun), HATS553-001B (0.20 -0.02/+0.01 Msun, 0.22 -0.01/+0.01 Rsun). We examine our sample in the context of the radius anomaly for fully-convective low mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5% systematic deviation between the measured radii and theoretical isochrone models.Comment: 17 pages, 8 figures, accepted for publication in MNRA