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49 results on '"Olcan, Dragan I."'

1. AI-Assisted Identification of State and Type of Flat-Panel Monitors in the Presence of EM Noise

Author

Ninkovic, Darko M. and Olcan, Dragan I.

Abstract

We present a method for identification of type and state (on/off) of flat-panel monitors, based on artificial neural networks and measurements of electromagnetic emanations in the presence of real-life noise, including other monitors in the vicinity. The proposed approach can identify monitor type and state with 99% accuracy (from a set of twelve). Instead of a single network, we use an ensemble of independently trained multilayer perceptron networks, since each training yields a different network. Further, we present an approach for automatic detection of significant frequency subranges of measured emanations, which eliminates less relevant inputs to neural networks and leads to reduction of their topological complexity, accelerates the training, minimizes the required set of experimental data and provides an overall insight into the spectral characteristics of emanations.

Published
2024
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7. Multiminima heuristic methods for antenna optimization

Author

Kolundzija, Branko M. and Olcan, Dragan I.

Subjects
Mathematical optimization -- Analysis, Antennas (Electronics) -- Design and construction, Circuit design -- Analysis, Circuit designer, Integrated circuit design, Business, Computers, Electronics, Electronics and electrical industries
Abstract

Two general approaches to multiminima optimization are considered. The first approach is based on repetition of a single minima method (e.g., the Nelder-Mead simplex applied to the best solution in a set of random trials). The second approach is based on a coarse estimation of local minima using initial set of points and local optimization starting from these local minima (e.g., random search as a generator of the initial set of points and Nelder-Mead simplex as a local optimizer). A comparison of various optimization algorithms has been done on one analytical problem and two well-known examples of antenna design. It is found that: a) the multiminima method based on coarse estimation enables finding more minima with smaller number of iterations than that based on repetition, b) the best multiminima methods are comparable with the best single minima methods in a number of iterations needed for finding the global minima, and c) the multiminima method based on coarse estimation restarted with different weighting coefficients of multiobjective cost function enables efficient Pareto optimization. Index Terms--Automated design, black-box optimization functions, heuristic multiminima antenna optimization, hybrid optimization algorithms, Nelder-Mead simplex, Pareto front.

Published
2006

45. GPU accelerated EM modelling in frequency domain: Comparison of performance of various GPU cards.

Author

Zoric, Dusan P., Olcan, Dragan I., and Kolundzija, Branko M.

Abstract

There is a constant interest in solving electrically larger and more complex electromagnetic (EM) problems on present day computers. Method-of-moments (MoM) is one of general-purpose numerical techniques for time-harmonic numerical analysis of EM systems with isotropic, linear and piecewise homogeneous materials [1]. [ABSTRACT FROM PUBLISHER]

Published
2012

47. Temporal Leakage in Analysis of Electromagnetic Systems.

Author

Djordjevic, Antonije R., Tosic, Dejan V., Zajic, Alenka G., Nikolic, Marija M., Olcan, Dragan I., and Jovanovic, Izabela D.

Subjects
ELECTROMAGNETISM, RADIO frequency, RADIO antennas, FOURIER transforms, ELECTROMAGNETIC waves
Abstract

Temporal leakage occurs when the time-domain response of a linear electromagnetic system is computed from frequency-domain data using the inverse discrete Fourier transform. Although the temporal leakage occurs in most practical cases, this phenomenon is not recognized in the literature covering electromagnetics, antennas, and microwaves. The purpose of the paper is to demonstrate and explain the temporal leakage. [ABSTRACT FROM AUTHOR]

Published
2012
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48. Advanced Techniques for Efficient Modeling of Electrically Large Structures on Desktop PCs.

Author

Kolundzija, Branko M., Tasic, Miodrag S., Olcan, Dragan I., Zoric, Dusan P., and Stevanetic, Srdjan M.

Subjects
MOMENTS method (Statistics), INTEGRAL equations, DIELECTRICS, PERSONAL computers, STRIP transmission lines
Abstract

The method of moments (MoM), applied to surface integral equations (SIEs) in the frequency domain, enables very accurate analysis of composite metallic and dielectric structures. Particularly, on a desktop PC, the electrical size of solvable problems is very limited by memory and time resources. This limit can be significantly extended by using advanced techniques, which are shortly revealed. The focus of the paper is to present results that illustrate current possibilities of MoM/SIEs solution on a desktop PC: (1) monostatic RCS of a cube of side 80 λ, (2) beam steering of an array of 30 by 30 microstrip patch antennas at 9.2 GHz, and (3) beam steering of 4 by 4 patch antennas at 5 GHz, placed on a 19 m long helicopter. [ABSTRACT FROM AUTHOR]

Published
2012

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