Search

Prezentacija koja obuhvata opšta znanja o slobodnom softveru, licencama slobodnog softvera, operativnom sistemu GNU-Linux i o nekoliko cross-platform aplikacija (programa).

Motivaciono predavanje po pozivu namenjeno studentima Mašinskog fakulteta, održano u Informatici a.d, 02.02.2023. godine.

Exact solution of a circuit model for a three-phase twelve-pulse rectifier with constant-voltage load and ac-side reactance for the continuous conduction mode is presented. Obtained results are compared to the results provided by sinusoidal approximation. It is shown that the sinusoidal approximation provides acceptable results at low output voltages, with the accuracy being decreased for the output voltages approaching to the discontinuous conduction mode boundary. In comparison to the exact solution, the sinusoidal approximation always provides slightly more optimistic prediction for the rectifier exploitation parameters. Computational complexity of the exact solution is the same as for the solution obtained applying sinusoidal approximation, having the same structure, but different parameters. In comparison to the six-pulse rectifiers of the same type, analyzed in previous publications, agreement between the solutions is better due to the increased pulse number and reduced harmonic content of the waveforms.

Presentation for a lecture held at Multiplier Event 2 - The VALENCE educational software environment and digital infrastructure, Skopje, Macedonia, May 09, 2022.

Чланак се бави феноменом слободног софтвера. Иницијално је објавлјен у часопису "Галаксија". Избор слика и обраду је урадио Станко Стојиљковић.

The presentation covers analysis of a problem that involves transmission lines and a light bulb, proposed in a popular science video. Detailed analysis is provided, covering lossless transmission lines, their step responses, transmission lines with loses, models of light bulbs, and analysis of nonlinear effects caused by the light bulbs. It is shown that both the problem and the solution are a bit too complex to be adequately analyzed in a popular science video.

U predavanju ��e u okviru 45 minuta biti rezimirano li��no iskustvo 31 godine rada u struci (oko 1.5 minut po godini), delom u nastavi, delom u nauci, delom u industriji. Oblasti koje ��e biti razmatrane su ra��unari, energetska elektronika, analogna elektronika, elektri��na merenja, automatizacija mernih sistema, industrijska automatizacija, telekomunikacije, kao i softver, sve prezentovano kroz konkretne primere li��nog iskustva, sa navo��enjem i razmatranjem razloga koji su dovodili do promene interesovanja i oblasti rada. Tako��e, bi��e predstavljena iskustva saradnje u zemlji i inostranstvu. Bi��e skrenuta pa��nja na ��injenicu da tr��i��te rada, iako ��esto predstavljano kroz idealizaciju, u sebi sadr��i suprotstavljene interese i to na razli��itim nivoima, gde unija lokalnih optimuma ne predstavlja ��eljeni i propagirani globalni optimum. Za razliku od uobi��ajenog pristupa po kome se lo��e ideje izostavljaju iz prezentacije, ovde ��e one biti uvr��tene i analizirane, po��to se na gre��kama najbolje u��i, a povoljno je da te gre��ke budu tu��e. Iskustvo rada u struci je slo��ena interakcija razvoja tehnologije i dru��tvenih odnosa na razli��itim nivoima. Glavni zaklju��ak je da je mogu��nost predvi��anja ograni��ena, kao kod prognoze vremena i drugih fenomena nelinearne dinamike. Rapidne promene tehnologije mogu��nost predvi��anja dodatno ote��avaju. Ba�� zato treba spremno do��ekati realnost i kroz obrazovanje se osposobiti za uspe��an odgovor na izazove budu��nosti. ��ta obrazovanje treba da pru��i, a jo�� vi��e ��ta studenti kroz obrazovanje treba da uzmu, bi��e obra��eno u predavanju.

This is a lecture held online in Skopje, Macedonia, for IEEE Macedonia Section. In the lecture, effects of the information revolution in education are addressed. The focus is in electrical engineering students and experiences with free textbooks and online teaching.

Presentation slides covering lecture "Computer-Aided Analysis of Three-Phase Rectifiers" held at Universitat Rovira i Virgili, Tarragona, sometime in 2008.

U članku se razmatraju posledice informatičke revolucije na obrazovanje, pre svega na publikovanje udžbenika, a zatim na generalizaciju pojma udžbenika na nastavne video materijale i masovne otvorene kurseve u kojima se kombinuju video sadržaji, pisani tekstovi i testovi za proveru znanja. Razmatraju se mogućnosti primene Creative Commons licenci i otvorenih repozitorijuma, kakav je Zenodo.

U predavanju će u okviru 45 minuta biti rezimirano lično iskustvo 30 godina rada u struci (1.5 minut po godini), delom u nastavi, delom u nauci, delom u industriji. Oblasti koje će biti razmatrane su računari, energetska elektronika, analogna elektronika, električna merenja, automatizacija mernih sistema, industrijska automatizacija, telekomunikacije, kao i softver, sve prezentovano kroz konkretne primere ličnog iskustva, sa navođenjem i razmatranjem razloga koji su dovodili do promene interesovanja i oblasti rada. Takođe, biće predstavljena iskustva saradnje u zemlji i inostranstvu. Biće skrenuta pažnja na činjenicu da tržište rada, iako često predstavljano kroz idealizaciju, u sebi sadrži suprotstavljene interese i to na različitim nivoima, gde unija lokalnih optimuma ne predstavlja željeni i propagirani globalni optimum. Za razliku od uobičajenog pristupa po kome se loše ideje izostavljaju iz prezentacije, ovde će one biti uvrštene i analizirane, pošto se na greškama najbolje uči, a povoljno je da te greške budu tuđe. Iskustvo rada u struci je složena interakcija razvoja tehnologije i društvenih odnosa na različitim nivoima. Glavni zaključak je da je mogućnost predviđanja ograničena, kao kod prognoze vremena i drugih fenomena nelinearne dinamike. Rapidne promene tehnologije mogućnost predviđanja dodatno otežavaju. Baš zato treba spremno dočekati realnost i kroz obrazovanje se osposobiti za uspešan odgovor na izazove budućnosti. Šta obrazovanje treba da pruži, a još više šta studenti kroz obrazovanje treba da uzmu, biće obrađeno u predavanju., Prezentacija održana 12.11.2020. godine na konferenciji Brand New Engineers u organizaciji studenata, online.

The paper presents a simple circuit for analog computation of space vector components on the basis of phase voltages. The space vector trajectory could be directly visualized by an oscilloscope. Proposed circuit consists of nine resistors only. An algorithm to compute the resistor values and programs that support the design are provided. The method is experimentally verified using a three-phase voltage source inverter model. Three methods to visualize recorded data are proposed, each capturing different aspect of the space vector trajectory.

This is a presentation of a keynote lecture at INDEL 2020 Conference. The presentation covers the author's twelve years long experience with free software in teaching and research, as well as some of his thoughts on that topic.

In this paper, suboptimal current injection in three‑phase diode bridge rectifiers that apply switching resistance emulators is analyzed. Two rectifiers are focused, one that applies filtering of the resistance emulator output current, and the other one that does not. Models that cover both the continuous and the discontinuous conduction mode of the rectifiers are developed. Optimization is performed, showing that both of the rectifiers provide about the same performance when the emulated resistance takes the optimal value. The results are experimentally verified.

In this paper, a bidirectional AC-DC converter is analyzed. The converter applies a half‑bridge thyristor rectifier and a recuperating thyristor bridge instead of a braking resistor. Recuperating mode of the converter is focused in the analysis, and it is shown that the converter exposes two operating modes within the recuperating mode, one characterized by negligible, and the other one characterized by significant distortion of the input voltages. Theoretical results are experimentally verified on a 10kW converter.

In this paper, a software supported DC voltage calibrator is presented, requiring a standard programmable signal generator, a digital voltmeter, and some free software components. After detailed analysis of the programmable signal generator applying an automated process, it is concluded that intrinsic precision is insufficient for the generator to be used as a voltage calibrator. Furthermore, offline calibration techniques as polynomial interpolation and lookup table compensation are ruled out due to the generator reference instability over temperature and time. As a solution, a closed loop method based upon a voltmeter and a control software thread is proposed. The method is verified experimentally.

Virtual instruments described in this paper utilize a digital oscilloscope as an acquisition module and a personal computer to process the data. Described instruments measure mean value, root-mean-square value, power, apparent power, power factor, displacement power factor, total harmonic distortion, efficiency, and compute the waveform spectra. The measurements are organized at several stages, to provide verification at intermediate result level. Measurement process is fully automated, covering data acquisition, data processing, and report generation. The system is realized applying free software exclusively, and all the programs presented in the paper are freely available.

Peak limiting current mode control method is analyzed focusing regions where period-1 limit cycle operation is unstable. It is shown that in these regions two operation modes might occur: higher period number discontinuous conduction mode, and unstable limit cycle continuous conduction mode. Mode boundaries are derived. The analysis is preformed applying both analytical and numerical techniques. The diagrams presenting the converter output current, the period number, and the converter averaged model open loop stability are presented.

In this document, a simple circuit constructed using a diode, a resistor, and a capacitor, utilized as a peak detector and/or as an envelope detector is analyzed. The analysis is approached by applying approximate methods and by a mix of exact and numerical methods, aiming design guidelines and understanding of the circuit operation. Approximate and exact approaches are compared, and a region where the approximate analysis provides adequate answers is identified. Ability of the circuit to track the envelope variations is analyzed, and it is shown to depend both on the circuit time constant and the output voltage value, i.e. the modulation signal frequency and the modulation index. Relevant relations are derived and presented. Finally, distortion of the output voltage caused by the output voltage ripple is addressed, and averaged model of the circuit is derived. It is shown that average of the output voltage over the carrier period is increased about three times when filtering of the output voltage is applied. Transfer function for averaged waveforms of the envelope detector is derived, containing slight attenuation and a real pole at the double of the carrier frequency.

This is a textbook that covers nine laboratory exercises for Electrical Measurements course. The exercises are focused to electronics majors and emphasize the use of computers. Free software tools are used, and the software designed for the lab exercises is freely available, written in Python.

This document contains presentation slides for Software Tools in Electronics course (Serbian: "Praktikum iz softverskih alata u elektronici"). The course covers basic usage of Ubuntu GNU/Linux operating system, including some command line tools, LaTeX, GNU Octave, gnuplot, Maxima and wxMaxima, and some basic Python programming, with emphasis in PyLab and SymPy.

This is a presentation about application of Python programming language in automating measurement processes.