Modeling of Impurities Evaporation Reaction Order in Aluminum Alloys by the Parametric Fitting of the Logistic Function

Advancements in computer capabilities enable predicting process outcomes that earlier could only be assessed after post-process analyses. In aerospace and automotive industries it is important to predict parts properties before their formation from liquid alloys. In this work, the logistic function was used to predict the evaporation rates of the most detrimental impurities, if the temperature of the liquid aluminum alloy was known. Then, parameters of the logistic function were used to determine the transition points where the reaction order was changing. Samples were heated to 610 °C, 660 °C, 710 °C, and 760 °C for one hour, after which the chemical analyses were performed and evaporation rates were calculated for Cd, Hg, Pb and Zn elements. The pressure inside the encapsulated area was maintained at 0.97 kPa. Whereas parameters that define the evaporation rate increase with the temperature increase, the maximum evaporation rates were deduced from the experimental data and fitted into the logistic function. The elemental evaporation in liquid-aluminum alloys is the best defined by the logistic function, since transitions from the first to zero-order-governed evaporation reactions have nonsymmetrical evaporation rate slopes between the lowest and the highest evaporation rate point

Microfossils and brachiopods from the Lower Barremian at Prekonozi, eastern Serbia

This paper presents the results of an integral biostratigraphical study based on orbitolinids and other benthic foraminifers, brachiopods and algae of a part of the Prekonozi section, eastern Serbia. The species identified are: Paracoskinolinal jourdanensis Foury & Moullade, P. sunnilandensis (Maync), Orbitolinopsis debelmasi Moullade & Thieuloy, Alpillina antiqua FOURY, Pfenderina globosa FOURY, Mayncina bulgarica Leug, Peibernes & Rey, Charentia cuvilleri Neumani and other foraminifers, and brachiopods: Cyclothyrisl pancici (Antula), Sellithyris sella (J. DE C. Sowerby), Dictyothyris elongata Smirnova, and Psilothyris tamarindus (J. de C. Sowerby). The examined limestones based on orbitolinids, are assigned to the Lower Barremian, earlier dated Upper Barremian/Lower Aptian

The latest geological study of the underlying productive layer of the "Garajevac Istok" deposit in Novi Bečej

In this paper, the latest geological study of the "Garajevac Istok" brick clay deposit near Novi Bečej is presented. The clay of the overlying productive layer of this deposit has been exploited by Polet from Novi Bečej since 2008 as raw material for the production of roof tiles. This study is focused on the underlying productive layer of soil, which has not yet been exploited due to the abundance of water in the working environment. Detailed studies by depth of the second silt-clay complex planned for exploitation were carried out. The obtained results confirm that the quality of the raw mineral materials meets the standards for tile production. This paper summarizes the results of the studies

Natural and artificial radioactivity in some protected areas of south east Europe

The primary aim of this research is the investigation of natural and artificial radioactivity in protected areas of Kopaonik, Vlasina, and Rila Mountains. Soil samples (including lake sediment), drinkable spring water and conifers at mentioned locations of Southeast Europe, are chosen as study objects due to their importance for people and the environment in global. Specific activities of Ra-226, Th-232, K-40, U-238, U-235, Cs-137, Pb-210, and Be-7 are determined using gamma spectrometry and the obtained values compared with literature and mean world values. Risk assessment parameters and the soil-plant transfer factor were determined for Ra-226, K-40, (CS)-C-137, and Pb-210. This is the first radioactivity study of high mountain areas of Vlasina and Kopaonik in Serbia and Rila in Bulgaria and as such a baseline measurement and foundation for future research

Recultivaction of opencast mine of clay "Garajevac Istok", near Novi Bečej

The surface exploitation of mineral raw materials is realized in the natural environment, causing the degradation of the narrower and wider space: the change of the physical appearance of the terrain and the degradation of the soil and autochthonous vegetation cover. The recultivation of the surface mine area, after the exploitation of mineral raw materials, is an important and mandatory measure in the function of environmental protection. In a biologically empty space, with damaged or destroyed natural content, in parallel with the slow and long-lasting process of spontaneous self-revitalization, technical and biological reclamation measures and procedures are applied to control and accelerate the revitalization process.The subject of this work is the design of reclamation on the surfaces affected by the exploitation of clay, on the example of the Garajevac Istok surface mine near Novi Bečej, with the aim of creating habitats for plant and animal life. The planned goals of the reclamation of the post-exploitation area of the Garajevac Istok surface mine will be realized by applying a combination of afforestation measures and spontaneous self-reclamation

Natural and artificial radioactivity in some protected areas of south east Europe

The primary aim of this research is the investigation of natural and artificial radioactivity in protected areas of Kopaonik, Vlasina, and Rila Mountains. Soil samples (including lake sediment), drinkable spring water and conifers at mentioned locations of Southeast Europe, are chosen as study objects due to their importance for people and the environment in global. Specific activities of 226Ra, 232Th, 40K, 238U, 235U, 137Cs, 210Pb, and 7Be are determined using gamma spectrometry and the obtained values compared with literature and mean world values. Risk assessment parameters and the soil-plant transfer factor were determined for 226Ra, 40K, 137Cs, and 210Pb. This is the first radioactivity study of high mountain areas of Vlasina and Kopaonik in Serbia and Rila in Bulgaria and as such a baseline measurement and foundation for future research. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III43009