Correction: Stević, Z. et al. Estimation of Parameters Obtained by Electrochemical Impedance Spectroscopy on Systems Containing High Capacities. Sensors 2009, 9, 7365–7373

In the original published version of this paper, the name and affiliation of the third coauthor was listed by mistake

Supercapacitors based on copper sulfides

Ova disertacija predstavlja doprinos razvoju superkondenzatora novog tipa zasnovanog na prirodnim sulfidima bakra. Ispitivanje superkondenzatora (zbog velikih kapacitivnosti, odnosno vremenskih konstanti) zahteva znatnu modifikaciju i prilagođavanje klasičnih elektrohemijskih metoda i instrumentalne tehnike. U okviru disertacije urađena je matematička analiza kojom su definisani parametri eksperimentalnih metoda, kako sedam modifikovanih standardnih, tako i dve nove – Dirakove naponske i nagibne strujne. Hardver i softver nephodan za njihovu realizaciju predstavlja značajan deo ove disertacije. Metode su najpre proverene na posebno konstruisanom fizičkom modelu – električnom kolu sa komercijalnim superkondenzatorom od 1,5F, kao i simulacijom na računaru. Sve metode su primenjene pri razvoju novog tipa superkondenzatora na bazi prirodnih minerala bakra – kovelina (CuS) i halkozina (Cu2S). Maksimalna dobijena kapacitivnost na halkozinu bila je oko 100F/cm2. Na kraju je realizovan i ispitan protip superkondenzatora sa halkozinom kao aktivnim elektrodnim materijalom.In this dissertation contribution is given in the development of a new kind of supercapacitors based on copper sulfide minerals. Examination of supercapacitors needs considerable modification of standard electrochemical methods and techniques because of the big time constants as a consequence of enormous high capacitancies. Parameters for modified electrochemical methods were obtained by mathematical analysis of such systems. Also, two new methods have been established – Dirack voltage pulse and linear sweep amperometry. Hardware and software for seven modified standard and two newly developed methods are an important part of the dissertation. The methods are firstly verified on specially constructed physical model of electrical circuit containing one 1,5F supercapacitor, and by simulation on PC. All methods and instrumental techniques were applied to develop a new kind of supercapacitors based on natural copper minerals covellite (CuS) and chalcocite (Cu2S). Maximum capacitance obtained on chalcocite was about 100 F/cm2. Finally, a prototype of supercapacitor with chalcocite as an active electrode material was realized

Temperature dependence of electric properties of GO and GO/WPA films on interdigital electrodes

In sensor devices the material of choice should be highly dependent on perturbation of environmental parameters. In order to achieve good sensitivity and selectivity of sensing devices to temperature, humidity or concentration of different gasses, the materials with adjustable properties are highly desirable. Electric properties of graphene oxide (GO) can be easily tuned by modification of surface chemistry and anchoring of functional compounds onto its two-dimensional structure. Prior to application of sensing device, research and development of materials system is the most essential step. In this work, the formation of GO and GO/12-tungstophosphoric acid (WPA) films with 6 wt.% of WPA on interdigital electrodes was investigated by variation of dip-coating parameters (receding angle and time between steps). Obtained films were thermally reduced in argon atmosphere after which optical microscopy was used to evaluate morphology and stability of deposited GO and GO/WPA films. Impedance spectroscopy was used to investigate the electric properties of the obtained films in range from 10 Hz to 100 kHz. Measured impedance values were correlated to the degree of material detachment and deposition parameters i.e. films showing the lowest impedance values had the smallest area of detached film. Additionally, impedance values were measured depending on the environment temperature which showed that GO/WPA films exhibit the lowest impedance values and good sensitivity to changes of temperature making it good a candidate for sensing devices.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Korišćenje obnovljivih izvora – pretvaranje geotermalne energije u električnu

According to the official definition, approved by the European Geothermal Energy Council (EGEC), geothermal energy is energy accumulated as heat below the surface of solid soil. Geothermal energy is thermal energy generated and stored in the Earth. It is generally defined as the part of geothermal heat that can be directly utilized as heat or converted into other types of energy. Geothermal resources vary by location and depth towards the Earth's core. Their use is possible for different purposes depending on their temperature. This paper presents the harnessing geothermal resources for electricity generation. There are three main types of geothermal power plants: dry steam plants, flash steam plants, and binary cycle plants. Dry steam plants pipe hot steam from underground into turbines, which powers the generator to provide electricity. Flash steam plants pump hot water from underground into a cooler flash tank. The formed steam powers the electricity generator. Binary cycle plants pump hot water from underground through a heat exchanger that heats a second liquid to transform it into steam, which powers the generator. In all mentioned systems the used fluids are recycled. It can be concluded that geothermal power plants work similarly to other power plants, but providing the steam for starting the turbine from the earth's interior. The fact that used fluids return to the ground makes geothermal energy resources renewable.Prema zvaničnoj definiciji, koju je odobrilo Evropski savet za geotermalnu energiju (European Geothermal Energy Council- EGEC), geotermalna energija je energija akumulirana kao toplota ispod površine čvrstog tla. Geotermalna energija je toplotna energija koja se generiše i skladišti u Zemlji. Generalno se definiše kao deo geotermalne toplote koji se može direktno koristiti kao toplota ili pretvoriti u druge oblike energije. Geotermalni resursi se razlikuju u zavisnosti od lokacije i dubine u odnosu na jezgro Zemlje. Njihova primena moguća je za različite svrhe u zavisnosti od njihove temperature. Ovaj rad prikazuje upotrebu geotermalnih resursa za proizvodnju električne energije. Postoje tri osnovna principa rada geotermalnih elektrana: suva para (dry steam), separisanje pare (flash steam) i binarni (binary cycle). Postrojenja na suvu paru izbacuju vruću paru iz unutrašnjosti Zemlje u turbine, a ona napaja generator koji daje električnu energiju. Postrojenja sa separisanjem pare pumpaju toplu vodu iz iz unutrašnjosti Zemlje u hladniji rezervoar. Nastala para pokreće generator električne energije. Postrojenja sa binarnim ciklusom pumpaju toplu vodu iz unutrašnjosti Zemlje kroz izmjenjivač toplote čime se greje drugi fluid i pretvara u paru koja pokreće generator. U svim pomenutim sistemima korišćeni fluidi se recikliraju. Može se zaključiti da geotermalne elektrane rade slično kao i druge elektrane, ali paru za pokretanje turbine obezbeđuju iz unutrašnjosti Zemlje. Činjenica da se korišćeni fluidi vraćaju u zemlju čini geotermalne izvore energije obnovljivim

Introduction to non-contact temperature measurement procedures using the Python programming language

Learning temperature measurement procedures is extremely important for students of the technical professions. The previous practice was mostly based on the study of contact methods of measurement, however, due to the progress of technology, there is a need for a more detailed introduction to non-contact temperature measurement procedures, such as thermovision. When studying thermovision, in addition to the thermovision camera, the software supplied with it is also used to analyze the obtained thermograms. However, in most cases this software is not suitable for use in a teaching process. Due to this, the paper presents a solution based on the use of a different type of software compared to the traditionally used software during the introduction to thermovision procedures. The entire code for the software was developed in the Python programming language using elements of computer vision, image analysis and other capabilities that Python offers through its various modules. The entire environment intended for learning was implemented using virtualization techniques. An adequate virtual machine was implemented using free software and open source software.Publishe

Solarna energetika – stanje i perspektive

Solarni sistemi u poslednje vreme beleže esponencijalni rast instalisane snage. Ostvareni ekonomski efekti podstiču dalji razvoj tehnologije, tako da se postiže sve veća energetska efikasnost uz sve niža investiciona ulaganja. Države dodatno pomažu merama podsticaja, posebno u uslovima krize drugih energenata, tako da se očekuje još veći rast u budućnosti. U radu je dat pregled stanja tehnologije i regulative, kao i projekcije za budućnost u Evropi i Srbiji.owadays, solar systems have recorded in an exponential increase in installed power. The achieved economic effects encourage further development of technology, so that increasing energy efficiency have been achieved with lower investments. Countries additionally help with incentive measures, especially in the states of the crisis of other energy sources, thus the greater growth is expected in the future. The paper provides an overview of the state of technology and legal regula-tions, as well as projections for the future in Europe and Serbia.The 10th ICREPS was held on October 17 and 18, 2022, in Chamber of Commerce and Industry, of Serbia, Belgrade

Energetski efikasni pulsno-reverzni režimi galvanizacije

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 increase 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 the suitable 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

The visualization of the medieval site of the Savinac monastery

Contemporary visualization techniques rely on new technological achievements which offer information data collection in the form of a three-dimensional model. Such 3D model is significant in the area of cultural heritage protection and specifically in the restoration processes of ruined monuments. The results of applications of both methods, terrestrial laser scanning (TLS) and photogrammetry, is 3D data in the form of point cloud, which is a base for 3D modelling process in adequate software, and accordingly, a creation of an objects’ 3D shape. In this paper, the results of data collecting at the medieval site of the Savinac monastery (twelfth century ), performed in 2018, by using both contemporary methods, is presented. The visualization of this particular site is of the major importance for cultural heritge of Serbia

The visualization of the medieval site of the Savinac monastery

Contemporary visualization techniques rely on new technological achievements which offer information data collection in the form of a three-dimensional model. Such 3D model is significant in the area of cultural heritage protection and specifically in the restoration processes of ruined monuments. The results of applications of both methods, terrestrial laser scanning (TLS) and photogrammetry, is 3D data in the form of point cloud, which is a base for 3D modelling process in adequate software, and accordingly, a creation of an objects’ 3D shape. In this paper, the results of data collecting at the medieval site of the Savinac monastery (twelfth century ), performed in 2018, by using both contemporary methods, is presented. The visualization of this particular site is of the major importance for cultural heritge of Serbia

Examining erosion resistance of ceramics for electrical engineering applications

In this research, two non-destructive testing (NDT) methods, thermal vision analysis and image analysis, were implemented for monitoring the surface changes- erosion of mullite based ceramic samples in conditions of cavitation exposure. Thermal imaging analysis was focused on determining temperature line profile at the end of the cavitation experiment. Image analysis is a powerful tool for quantification of degradation level caused by different impacts and conditions. Based on the results of image analysis, the degradation level during the testing was determined, as well as number of formed pits with their characteristics (average diameter and area). The results performed by both methods were discussed in order to obtain optimal procedure that should be followed for estimating degradation caused by cavitation erosion