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Bismuth germanium oxide Bi12GeO20 (BGO) has very interesting electrical, optical and magnetic properties. In order to make devices based on this material more flexible, its powder was used for preparing polymer composites. This study reports investigation of the effects of using different solvents and polymers in preparation of BGO composite on the microstructural and optical behaviour of the resulting material. Preparation of such composites by a solution casting method is described. Poly (methyl methacrylate) (PMMA) and polystyrene (PS)) were used as matrix materials and acetone and chloroform as solvents. Their microstructure and the quality of BGO dispersion and deaggregation in polymer matrix were analyzed by SEM, Raman, XRD and optical spectroscopy. The influence of particle size distribution, their shapes, and concentration on the optical transmission is calculated based on Mie scattering theory and discussed, too. (C) 2016 Elsevier B.V. All rights reserved.

Predmet istraživanja ove doktorske disertacije je izučavanje uticaja ulaznih podataka na polja koncentracija zagađujućih materija u donjem graničnom sloju atmosfere dobijenih primenom matematičkih modela kao i usložnjavanje matematičkog modela atmosferske disperzije Gausovog tipa, čiji je rezultat generalisan Gausov disperzioni model. Cilj istraživanja u ovom radu je realizacija i primena kompleksnog matematičkog difuzionog modela, koji uzima u obzir složene atmosferske procese u sloju mešanja, kao i razrađena procedura za pripremu ulaznih podataka, koji omogućavaju praćenje rasprostiranja zagađujućih materija u okolini industrijskih i nuklearnih izvora na rastojanjima do 10-20 km, gde su koncentracije zagađujućih materija iz tih izvora obično najveće i gde se dobijaju prve informacije važne za ranu najavu akcidenata i pokretanje kontramera. Pored navedenog cilj je i verifikacija matematičkog modela pisanog u FORTRAN programskom jeziku (NFS-Vinca) preko meteoroloških podataka koji su dobijeni u realnom vremenu, kao i procena rasprostiranja polutanata na osnovu idealizovane situacije sa zadatim vetrom i klasama stabilnosti.Istraživanja u okviru doktorske disertacije polaze od hipoteze da koncentracije zagađujućih materija koje se emituju u atmosferu iz veštačkih izvora zavise od karakteristika izvora, atmosferskih procesa u donjem graničnom sloju atmosfere, tzv. sloju mešanja, karakteristika tla i fizičko hemijskih karakteristka zagađujućih materija. Kod nuklearnog postrojenja modelovana je koncentracija radioaktivnosti u vazduhu sledećih radionuklida: 137Cs, 90Sr, 60Co, 154Eu. Kod industrijskog postrojenja određivan je nivo koncetracije PM10.U prvom delu rada, matematičkim modelom su dobijene prosečne godišnje koncentracije aktivnosti u vazduhu, koncentracije suve i vlažne depozicije kao i ukupna godišnja doza koju bi primio hipotetički stanovnik u blizini nuklearnog reaktora. Rezultati modelovanja su upoređeni sa vrednostima koncentracije radioaktivnosti iz IAEA (I, The subject of this doctoral dissertation was the influence of the input data on the pollutant concentration in the lower atmospheric boundary layer obtained by mathematical model, which was the result of generalized Gaussian dispersion model. The aim was implementation of complex mathematical diffusion model and development procedures which enable the monitoring of dispersion of pollutants in the environment of industrial and nuclear power plants within 10-20 km, where the concentration of pollutants from these sources is usually the highest, and also for early warning for accidents and countermeasures. In addition is the verification of the mathematical model in FORTRAN programming language (NFS-Vinca) through meteorological data obtained in real time, as well as the evaluation of dispersion of pollutants on the basis of idealized situations specified with wind classes and stability.Research in this dissertation is based on the hypothesis that the concentrations of pollutants emitted into the atmosphere from artificial sources depend on the characteristics of the sources of atmospheric processes in the lower atmospheric boundary layer, soil characteristics and the physical and chemical characteristics of pollutants. For the nuclear power plant, radioactivity concentration of the following radionuclides 137Cs, 90Sr, 60Co, 154Eu was determined. For thermal power plant the concentration level of PM10 was measured.The air pollution dispersion model is based on average annual activity concentration in the air, deposition on soil and field of total annual dose to a hypothetical resident contaminated by air in the vicinity of a nuclear reactor. The results of modeling were compared with values from an IAEA publication for a given scenario of radionuclide emission to the atmospheric boundary layer. Due to small differences in the results, compared to the IAEA recommended model, the model presented in the thesis can be used as a basis for this type of analysis. The maximum

High quality bismuth germanium oxide single crystals were irradiated by a femtosecond pulsed laser beam of increasing power. Analyses performed on irradiated and unirradiated samples showed significant changes in transmittance, transmission spectra, sample color, Raman spectra, X-ray diffraction (XRD) pattern, Verdet constant, magneto-optical property, and absorption coefficient. After irradiation, the transmission spectra values increased whereas anisotropy detected in the transmission spectra of unirradiated samples disappeared. The change of color caused by irradiation was noticeable to the naked eye. The XRD measurements confirmed structural changes induced by laser irradiation, i.e., the laser-beam-incident side of the sample became almost amorphous, whereas the side opposite to the incident can be indexed to the Bi12GeO20 compound. Irradiation caused increase of Raman spectra peaks with the exception of crystal peaks of type E, which disappeared. The femtosecond pulsed laser irradiation can be used to improve bismuth germanium oxide single crystal optical properties. (C) 2016 Elsevier Ltd. All rights reserved.

Research activities of Vinca Institite have been based on two heavy water research reactors: a 10 MW one, RA, and zero power, RB. Reactor RA was operational from 1962 to 1982. In 2010, spent fuel has been sent to the country of origin, and the reactor now is in decommissioning. During the operational phase of the reactor there were no recorded accidental releases into the environment, only operational ones. Results of the environmental impact assessment of the assumed emission of radionuclides from the ventilation of nuclear reactor RA in Vinca to the atmospheric boundary layer are presented in this paper. Evaluation was done by using the Gaussian straight-line diffusion model and taking into account characteristics of the reactor ventilation system, the assumed emission release of radioactivity (from the literature), site-specific meteorological data for six-year period and local topography around nuclear reactor, and corresponding dose factors for inventory of radionuclides. Based on the described approach, and assuming that the range of appropriate meteorological data for six year period for the application of described mathematical model is enough for this kind of analysis, it can be concluded that the nuclear reactor RA, in the course of its work from 1962 to 1982, had no influence on the surrounding environment through the air above regulatory limits.

In this study, we point to loss of accuracy in representing a field of air pollution concentration due to reduction of number of monitoring points or changes in their location. Using a Gaussian-type diffusion model, a high resolution concentration field was generated from 17 points representing the actual distribution of possible pollution sources. The starting grid consisted of 90 601 points. Then we reduced number of points by two orders of magnitude, forming the grid of 961 points. After that, the second reduction to 36 points was performed, still forming a regular grid. Finally, we had 16 points whose positions are in a qualitative agreement with the actual distribution of sampling stations in the area.

The paper presents a system for automatic prevention of raising of ashes from dedicated landfills based on a simple mathematical model which has modest entry requirements for meteorological data. Such an approach is efficient enough and enables fast information retrieval, Le., zones with different concentrations of dust in the air, enabling quick start of counter measures to reduce emissions of ashes into the air. The system hardware consists of an automatic weather station, set of meters that determine moisture of ash, set of remotely managed sprinklers, computers, microprocessor and microcontroller based elements for the local acquisition and management of the executive elements and modules for wireless data transfer. An original software application for the system management has been developed. Within the application there is a module that allows entering of all data necessary to configure the system, as well as data about sensors and sprinklers. Based on the meteorological input data, measured moisture content of the ashes, and on the basis of determined functional dependencies, special software module operates sprinklers for soaking the surfaces from which the ashes is emitted into the air, in order to eliminate these emissions. The system, based on the developed mathematical model, predicts the propagation of ashes through the air, as well as dry and wet deposition, in real-time. The system automatically stores all the data relevant to the future analyses and reporting. The system is designed and implemented as modular and open. A custom developed graphical user interface serves as Man-Machine Interface (MMI). By using the TCP/IP connection it could be easily connected with the other information systems.

Thermal power plants Nikola Tesla A and B are large sources of ash from their ashes/slag deposit sites Total sizes of ashes/slag depots are 600ha and 382ha, with active cassettes having dimensions similar to 200 ha and similar to 130 ha The active cassettes of the disposal sites are covered by rather large waste ponds the sizes of vary depending on the working condition of a sluice system and on meteorological conditions Modeling of ash lifting was attempted using results from the dust lifting research The relation between sizes of ponds and air dust concentration in the vicinity of ash disposal sites was analyzed As expected, greater sizes of dried disposal site surfaces in combination with stronger winds gave greater dust emission and greater air dust concentration