Abstract Pulse-reverse power modes are used in galvanotechniques in order to obtain coatings with better characteristics in terms of gloss, adhesion, tracking sharp edges and uniform distribution of deposits on complex shape objects, compared with the coatings produced by constant current modes. Pulse-reverse modes also allow the use of a higher current density, and thus the production speed of electroplating cells increases. Systems for standard electroplating of copper, silver and gold are optimised by the suitable choice of duration and intensity of the pulses. It is shown that coatings with satisfactory quality can be deposited using higher current density, different modes of pulsed current in a very short period of time, without expensive and often dangerous additives in the electrolyte. Parameters of the model for certain electrochemical systems were determined by modelling and computer simulation, so the system behaviour under different circumstances becomes predictive.

Mechanical shock of zircon based ceramic induced by cavitation erosion testing was investigated in this study. Several parameters were followed in order to determine level of material degradation during the cavitation erosion testing. Mass loss was taken as a conventional criterion for material degradation, while the level of surface degradation was evaluated by image and thermal imaging analyses. Results show high cavitation resistance of zircon ceramics and their suitability when vigorous cavitation erosion environment is expected.

Pulse reverse power modes are used in order to obtain metal coatings with similar or better characteristics, compared with the coatings produced by constant current. Pulse reverse modes in-crease production and energy efficiency of electroplating cells with the use of higher density currents. In this paper, we investigate optimisation of systems for standard electrodeposition by choosing thesuitable duration and intensity of the pulses. It was shown that energy efficiency of the process can be achieved with satisfactory quality of coatings and without expensive and often dangerous additives in the electrolyte.

1 University of Belgrade, Institute of Chemistry, Technology and Metallurgy, Belgrade, Serbia 2 Prydniprovsk State Academy of Civil Engineering and Architecture, Dnipropetrovsk, Ukraine 3 University of Zenica, Faculty of Metallurgy and Material Science, Zenica, Bosnia and Herzegovina 4 University of Belgrade, Faculty of Technology and Metallurgy, Belgrade, Serbia 5 University of Belgrade, Technical Faculty in Bor, Bor, Serbia * E-mail: zstevic@tfbor.bg.ac.rs

Following the global trends and accordingly to the energy conditions, wind turbines are being succesfully built in Serbia, which leads to an increase in the fund of knowledge in this field. In the paper, on the basis of general geotechnical conditions in Serbia, the most common types of wind turbine foundations will be presented. Problems of the load analysis of these structures will be presented in brief, and also the conceptual requirements in their design. Connection between the tower and the foundation will be briefly described as well. Despite the global aspiration to generalize and industrialize this aspect of the construction of wind turbines, in specific cases remains a number of issues, regarding component materials, the application of standards and design codes, which are usually not adjusted to the design of wind turbine foundations.

In this paper the ability of three natural zeolites from different localities (Vranjska banja-VB, Igros-I and Baia Mare-BM deposits) to remove copper has been investigated. These three zeolites were subjected to the elementary analysis as well as XRDP and DTA/TG analysis due to complete characterization. Cation exchange capacity of VB, I and BM zeolites were 150.1, 169.2, and 176.5 meq/100g. The maximum adsorption capacity for the copper adsorption on VB, I and BM-zeolites were 7.75, 8.51, and 11.18 mg/g. Based on the obtained results the mathematical expression that describes correlation between the CEC and copper adsorption capacity has been developed. This linear dependance has been tested with the vast variety of experimental results. According to this expression it is possible to predict the copper adsorption capacity for different zeolites based only on their CEC value.

Increase of greenhouse gases concentration in the atmosphere, mainly carbon dioxide, which leads to global warming, indicates the need to take actions to reduce use of energy from carbon sources. The building sector is the largest consumer of energy, and thereby the largest emitter of greenhouse gases. In this paper the possibilities of achieving "near net zero emission" vision, in the residential sector, by the year 2050, were analysed. The necessary policies and technical energy efficiency measures were analysed, that could be applied in the building sector in Bosnia and Herzegovina by 2050. Large amount of energy is used for space heating and hot water, mainly from fossil fuels, which significantly contributes to air pollution and global warming. Specific energy consumption for space heating in Bosnia and Herzegovina is several times higher than in EU countries with the similar climate conditions. Therefore, it is necessary to reduce energy consumption significantly, ie to increase energy efficiency. It is also necessary to deploy the potential of renewable energy use in buildings and to use buildings as energy producers. In this way, in the long term, energy costs in buildings would be significantly reduced, as well as dependence on energy imports and the need for building of new capacities for energy generation. From other side, employment would be increased while emissions of pollutants and greenhouse gases would be reduced. In this paper, due to the availability of reliable data on energy consumption for the Sarajevo Canton, the necessary policies and measures to promote energy efficiency were analysed, that could be applied in the residential sector in the Sarajevo Canton.

The increasing levels of industrial wastewater released to the environment present a serious threat to human health, living resources, and ecological systems. Fe-modified zeolites were developed and tested for removal of Cu2+ and Zn2+ from contaminated water. The surfaces of the naturally occurring zeolite, clinoptilolite, were modified with Fe(III) oxyhydroxides using three different methods, denoted I, II, and III (FeCli1, FeCli2, and FeNaCli1, respectively). The oxyhydroxides were prepared in Method I using 0.1 M FeCl3·6H2O in an acetate buffer (pH = 3.6); in Method II, using 10ai] FeCl3·6H2O solution in 0.1 M KOH (pH = 10); and Method III was the same as Method I except the clinoptilolite was pretreated with NaCl. Newly synthesized materials from these three methods were then tested for their ability to enhance the sorption capacity for Cu and Zn compared to the natural sample (Cli). Powder X-ray diffraction measurements and the chemical composition of these modified samples confirmed that clinoptilolite maintained its structure while amorphous Fe3+ species were synthesized. The specific surface area (BET method) of both the natural and modified clinoptilolite increased by 2 and 7.5 times for Methods I and II, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy revealed that CaO was formed during Method I (FeClii). Throughout the adsorption process, the hydrolysis of CaO and the release of OH− caused the precipitation of Cu and Zn hydroxide, which made the determination of the sorption capacity of FeClii impossible. This phenomenon was avoided in Method III (FeNaClii) because of the absence of exchangeable Ca2+. The adsorption experiments with Method II resulted in double-enchanced adsoprtion capacity. Laboratory batch experiments revealed that the sorption capacities increased in the following order: Cli < FeCli2 < FeNaCli1, for Cu: 0.121 mmol/g < 0.251 mmol/g < 0.403 mmol/g and for Zn: 0.128 mmol/g < 0.234 mmol/g < 0.381 mmol/g.