Faculty of Technical Sciences, Čačak

Permanent URI for this collectionhttps://dspace.unic.kg.ac.rs/handle/123456789/8215

The Faculty is accredited and it offers accredited Undergraduate, Integrated, Master and Doctoral study programmes. The cooperation with leading domestic and International companies such as Oracle, Microsoft, Intergraph, Fujitsu and Schneider-electric enabled our students to gain skills through practice in well-known companies, and prompted our graduates to be distinguished experts in modern technologies.

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5G tool for evaluation and comparision of energy efficiency of mobile radio channel using second-order statistics
(2020) Stefanovic, Nenad; Kar A.; Mladenovic, Vladimir
© Published under licence by IOP Publishing Ltd. In order to increase energy efficiency over transmissions channels, common approach for optimization tasks is by means of channel's second-order statistics. Actual channel modeling tools for 5G networks end with channel's first-order statistics, although these metrics are not sufficient when channel conditions are rapidly changing, either in time, frequency or space. In this paper, we establish a tool for evaluation and comparision of energy efficiency of mobile radio channel using its second-order statistics, especially level crossing rate (LCR) and average fade durations (AFD), as they can implicitly pinpoint to transmission configurations that are energy efficient or, as oposit, become a waste of energy. Using both deterministic and stochastic channel modeling, we present results after simulations of Rayleigh channel for narrowband case and further extend it to passband cases, suitable for 5G scenario. We conclude about the energy efficiency of different transmission schemes used by the 5G physical layer observing LCR and AFD values.
A Comparison of comprehension processes in sign language interpreter videos with or without captions
(2015) Debevc M.; Milošević, Danijela; Kozuh, Ines
©2015 Debevc et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. One important theme in captioning is whether the implementation of captions in individual sign language interpreter videos can positively affect viewers' comprehension when compared with sign language interpreter videos without captions. In our study, an experiment was conducted using four video clips with information about everyday events. Fifty-one deaf and hard of hearing sign language users alternately watched the sign language interpreter videos with, and without, captions. Afterwards, they answered ten questions. The results showed that the presence of captions positively affected their rates of comprehension, which increased by 24% among deaf viewers and 42% among hard of hearing viewers. The most obvious differences in comprehension between watching sign language interpreter videos with and without captions were found for the subjects of hiking and culture, where comprehension was higher when captions were used. The results led to suggestions for the consistent use of captions in sign language interpreter videos in various media.
A comparison of methods for three-class mammograms classification
(2017) Milosevic, Marina; Jovanovic, Zeljko; Jankovic, Dragan
© 2017 - IOS Press and the authors. All rights reserved. Background: Mammography is considered the gold standard for early breast cancer detection but it is very difficult to interpret mammograms for many reason. Computer aided diagnosis (CAD) is an important development that may help to improve the performance in breast cancer detection. Objective: We present a CAD system based on feature extraction techniques for detecting abnormal patterns in digital mammograms. Methods: Computed features based on gray-level co-occurrence matrices (GLCM) are used to evaluate the effectiveness of textural information possessed by mass regions. A total of 20 texture features are extracted from each mammogram. The ability of feature set in differentiating normal, benign and malign tissue is investigated using a Support Vector Machine (SVM) classifier, Naive Bayes classifier and K-Nearest Neighbor (k-NN) classifier. The efficiency of classification is provided using cross-validation technique. Support Vector Machine was originally designed for binary classification. We constructed a three-class SVM classifier by combining two binary classifiers and then compared his performance with classifiers intended for multi-class classification. To evaluate the classification performance, confusion matrix and Receiver Operating Characteristic (ROC) analysis were performed. Results: Obtained results indicate that SVM classification results are better than the k-NN and Naive Bayes classification results, with accuracy ratio of 65% according to 51.6% and 38.1%, respectively. The unbalanced classification that occurs in all three classification tests is reason for unsatisfactory accuracy. Conclusions: Obtained experimental results indicate that the proposed three-class SVM classifier is more suitable for practical use than the other two methods.
A contribution to the research of children protection in use of internet
(2017) Denic N.; Nesic, Zoran; Radojicic, Miroslav; Petković D.; Stevanovic, Milena
© 2017, Strojarski Facultet. All rights reserved. The main aim of this paper is to study the current state of children protection in their use of the Internet. The research includes a consideration of the factors influencing the protection of children from various aspects, based on the test results of the children, their parents and teachers. The results suggest a pronounced influence of the specific social circumstances of the environment in which the research study was conducted. With regard to the education of children, where schools and teachers play an important role, the paper highlights the importance of professional and methodical applicable IT education at educational institutions, the use of new information technologies in education, with an emphasis on the threats on the Internet, security on the Internet, the prevention of violence on the Internet, the rights of children on the Internet and the rules for a safe Internet use in relation to age. This study was carried out on the example of a case study.
A Family of Adaptive Volterra Filters Based on Maximum Correntropy Criterion for Improved Active Control of Impulsive Noise
(2021) Gowtham G.; Burra S.; Kar, Asutosh; Ostergaard, Jan; Sooraksa P.; Mladenovic, Vladimir; Haddad, Diego
Linear active noise control (ANC) systems have been used in the past to effectively suppress Gaussian noise. A practical ANC system must consider nonlinearities in the secondary path with a non-minimum phase. For an ANC system to effectively operate in a modern-day acoustic environment with multiple electrical/electronic systems operating in the vicinity, the reference noise source is taken as a non-Gaussian stochastic process. Linear systems have shown unacceptable performance in countering the disturbances that are impulsive in nature. Considering these issues, we propose a family of adaptive algorithms for ANC systems that employ a second-order Volterra filter for accurate modeling of the impulsive disturbances. We utilize the maximum correntropy criterion as the cost function to improve the adaptive filtering process, which generates the most appropriate output signal in the ANC system’s successive iterative stages. The proposed algorithms feature dynamic learning-rate parameters, which improve the tracking performance of the algorithms. Also, a careful selection of the Volterra filter’s kernel size in the proposed algorithms ensures a balance between system stability and convergence rate. These parameters are made automatically adjustable, based on the residual error and the reference input signals, to optimize performance in non-Gaussian environments. A comparison of the proposed algorithms with its counterparts is presented through computer simulations in terms of average noise reduction for different levels of impulsive noise. The proposed algorithms are also compared with each other to find the best performing algorithm in a non-Gaussian environment. Achieved results exhibit the effectiveness of the proposed algorithms in their ability to attenuate impulsive noise in comparison with the existing adaptive algorithms for ANC systems. Later, the proposed algorithm has been implemented for speech enhancement, where the noise from the speech sample is identified and removed using an adaptive filter algorithm. Simulations reveal that the devised algorithm can effectively denoise speech signals. Further, in the last part of the paper, the VF-MCCRMC is modified in accordance with the energy of the error signal, and the simulation results demonstrated the improvement in stability and error performance.
A few remarks on divergent sequences: Rates of divergence II
(2010) Đurčić, Dragan; Kocinac, Ljubisa; Žižović, Mališa
We continue (and, in a sense, close) our investigation begun in the paper Djurčić et al. (2009) [10] concerning quotient speed of divergence of sequences of positive real numbers and its relations with selection principles and games. By the way, we show a theorem of the generalized Galambos-Bojanić-Seneta type. © 2009 Elsevier Inc. All rights reserved.
A FPGA system for QRS complex detection based on Integer Wavelet Transform
(2011) Stojanović R.; Karadaglic D.; Mirković M.; Milošević, Danijela
Due to complexity of their mathematical computation, many QRS detectors are implemented in software and cannot operate in real time. The paper presents a real-time hardware based solution for this task. To filter ECG signal and to extract QRS complex it employs the Integer Wavelet Transform. The system includes several components and is incorporated in a single FPGA chip what makes it suitable for direct embedding in medical instruments or wearable health care devices. It has sufficient accuracy (about 95%), showing remarkable noise immunity and low cost. Additionally, each system component is composed of several identical blocks/cells what makes the design highly generic. The capacity of today existing FPGAs allows even dozens of detectors to be placed in a single chip. After the theoretical introduction of wavelets and the review of their application in QRS detection, it will be shown how some basic wavelets can be optimized for easy hardware implementation. For this purpose the migration to the integer arithmetic and additional simplifications in calculations has to be done. Further, the system architecture will be presented with the demonstrations in both, software simulation and real testing. At the end, the working performances and preliminary results will be outlined and discussed. The same principle can be applied with other signals where the hardware implementation of wavelet transform can be of benefit.
A ground temperature profile sensor based on NTC thick film segmented thermistors: Main properties and applications
(2018) Aleksić P.; Mitrovic, Nebojsa; Lukovic̀ M.; Veljovic Jovanovic, Sonja; Luković K.; Nikolic, Maria; Aleksić O.
© 2001-2012 IEEE. A new ground temperature profile sensor comprising of a row of thermistors enables a large number of equidistantly arranged measuring points. The row of thermistors was formed using a group of negative temperature coefficient thick film segmented thermistors connected in series. After that calibration of the DC thermistor resistance R was performed at room temperature and the sensor was placed in a hole drilled on the lawn. DC resistances R of the row of thermistors were measured versus depth z as a parameter and converted to actual temperature T(z) in the ground using the Steinhart-Hart equation. The temperature profile of the ground depending on deepness z and time t as a function T(t, z) was measured on different days during one year in the early morning and in the afternoon. The temperature at the ground surface was compared with the temperature of the deepest sensor point in the ground. Thermal diffusivity D of the ground was determined using measured data T(t, z) in the periods of steady ground temperatures. The new ground temperature profile sensor was realized to investigate the correlation between air and ground temperature, observation of ground temperature profile changes and heat exchange (heat transfer, diffusion, gradient, and heat flow direction) through the ground top layer and finally humidity estimation versus deepness.
A high-sensitive current-mode pressure/force detector based on piezoelectric polymer PVDF
(2018) Petrovic, Predrag; Pavlović, Vladimir; Vlahović B.; Mijailovic, Vladica
© 2018 Elsevier B.V. This paper introduces new electronic sensor circuits based on the usage of a piezoelectric Polyvinylidene fluoride-PVDF pressure detector coupled with a current-mode instrumentation amplifier, Schmitt comparator, and only grounded resistors. Pressure/force is measured in terms of the charge generated by the PVDF element as a result of the direct piezoelectric effect. The experimental test results demonstrated that the dynamic pressure response, the sensitivity and linearity of the designed sensor were higher than the sensitivity and linearity of a traditional piezoelectric sensor. The sensitivity of the PVDF sensor was 0.08 mV/Pa. The detector is calibrated over a frequency range of 1 Hz–1 kHz. The proposed signal conditioning electronics offer a potential for future miniaturization in order to be integrated with different commercial devices, for detecting certain tiny activities including finger movements, robotics and smart electronic devices.
A hybrid multi-output approach to optimisation of pvc pipe quality characteristics
(2021) Krstić A.; Nikolić, Djordje; Papić, Miloš
A hybrid multi-output approach which combined the Taguchi method and fuzzy logic was used in this research in order to optimise the mechanical and physical properties of PVC pipes. Eight techological parameters which mostly define the extrusion process were taken into consideration in order to obtain the best possible results for six measurable quality characteristics of PVC pipes. Eighteen experiments with the same number of different parameter value sets were conducted resulting in eighteen various PVC pipe samples. The sample from the second experiment showed the highest value of comprehensive output measure (COM = 0.615), while the lowest COM value (0.359) was noted with the sample no. 13. The results of ANOVA revealed that traction speed is the most significant parameter affecting multiple characteristics with contribution of 28.86%. The optimum combination of factors and their levels is A1, B3, C3, D2, E2, F3, G3, H2 – the sample produced at traction speed of 8.8 m/min, nozzle temperature of 211℃, expander doser speed of 23.2 rpm, extruder screw speed of 17.5 rpm, coextruder screw speed of 40.6 rpm, barrel temperature of 178 ℃, extruder mixture doser speed of 28.1 rpm and the coextruder mixture doser speed of 36.4 rpm.
A laboratory setup for magnetic filed distribution monitoring
(2016) Peulic A.; Damnjanović Đorđe; Krneta, Radojka
© 2015 IEEE. Nowadays, electrical and computers engineers are making their careers in designing smart, real time data acquisitions systems. This paper presents the computer laboratory setup and teaching methodology design to meet the needs in teaching magnetic field distribution. In modern world people spend a lot of time at their workplace. Because we live in age of electronic, usually working environment is surrounded with many different type of electric devices, e.g. telecommunication equipment, power grid, computers, mobile devices, different type of displays etc. Beside exposure to the influence of electromagnetic radiation from natural sources people are exposed to the influence of electromagnetic radiation from mentioned electronic devices from their working environment. The courses named Computer Control System and Remote Control allow the students to apply their previous knowledge of electrical sensors, microcontrollers systems, communications and software engineering to experience magnetic field distribution by designing and implementing large scale individual projects within semester. A flexible hardware platform accompanied by application and teaching methodologies allow quick completion of course exercises.
A literature review of empirical research on the effects of digital games on learning styles and multiple intelligences
(2017) Aleksic, Veljko; Ivanovic, Mirjana
© 2017, FACTEACHEREDUCATION. All rights reserved. The paper presents a review of literature resources that studied the effects of digital games on students’ learning and intelligence. The research included 5,740 scientific papers from 11 electronic repositories that presented various evidence of multidimensional impact of digital games on students. Categorization and application of multiple qualitative criteria identified 36 representative papers that presented empirical evidence. Various indicators and benchmarks used in papers were analysed, taking into account the methodological limitations. The results confirm the complex relations between digital games and learning styles and multiple intelligences on which the recommendations and questions for future research are created.
A model for determiningweight coefficients by forming a non-decreasing series at criteria significance levels (NDSL)
(2020) Žižović, Mališa; Pamucar, Dragan; Ćirović, Goran; Žižović, Miodrag; Miljković, Boža
© 2020 by the authors. In this paper, a new method for determining weight coefficients by forming a non-decreasing series at criteria significance levels (the NDSL method) is presented. The NDLS method includes the identification of the best criterion (i.e., the most significant and most influential criterion) and the ranking of criteria in a decreasing series from the most significant to the least significant criterion. Criteria are then grouped as per the levels of significance within the framework of which experts express their preferences in compliance with the significance of such criteria. By employing this procedure, fully consistent results are obtained. In this paper, the advantages of the NDSL model are singled out through a comparison with the BestWorst Method (BWM) and Analytic Hierarchy Process (AHP) models. The advantages include the following: (1) the NDSL model requires a significantly smaller number of pairwise comparisons of criteria, only involving an n-1 comparison, whereas the AHP requires an n(n-1)/2 comparison and the BWM a 2n-3 comparison; (2) it enables us to obtain reliable (consistent) results, even in the case of a larger number of criteria (more than nine criteria); (3) the NDSL model applies an original algorithm for grouping criteria according to the levels of significance, through which the deficiencies of the 9-degree scale applied in the BWM and AHP models are eliminated. By doing so, the small range and inconsistency of the 9-degree scale are eliminated; (4) while the BWM includes the defining of one unique best/worst criterion, the NDSL model eliminates this limitation and gives decision-makers the freedom to express the relationships between criteria in accordance with their preferences. In order to demonstrate the performance of the developed model, it was tested on a real-world problem and the results were validated through a comparison with the BWM and AHP models.
A model of information flow management in the function of business processes improvement
(2016) Nesic, Zoran; Ljubic L.; Radojičić, Miroslav; Vesić Vasović, Jasmina
© 2015 IEEE. This paper presents a model of information flow in the area of the relations of obligations, which is applied at the enterprise Parking Service Kragujevac, Serbia, which can also serve as a general reference model for building the customized model of the enterprise. According to their scope and complexity, the processes that take place within the legal department belong to the more complex processes in an enterprise. This paper presents a model of displayed information flows with the aim to improve the quality of business processes in the specified area and the implementation of the information system.
A Multi-Layered Image Format for the Web with an Adaptive Layer Selection Algorithm
(2018) Tair M.; Mihajlović, Aleksandra; Savanovic N.; Sarac M.
A Multigraph-Defined Distribution Function in a Simulation Model of a Communication Network
(2022) Miletić, Andrijana; Pokrajac I.; Pena-Pena, Karelia; Arce G.; Mladenovic, Vladimir
We presented a method based on multigraphs to mathematically define a distribution function in time for the generation of data exchange in a special-purpose communication network. This is needed for the modeling and design of communication networks (CNs) consisting of integrated telecommunications and computer networks (ITCN). Simulation models require a precise definition of network traffic communication. An additional problem for describing the network traffic in simulation models is the mathematical model of data distribution, according to which the generation and exchange of certain types and quantities of data are realized. The application of multigraphs enabled the time and quantity of the data distribution to be displayed as operational procedures for a special-purpose communication unit. A multigraph was formed for each data-exchange time and allowed its associated adjacency matrix to be defined. Using the matrix estimation method allowed the mathematical definition of the distribution function values. The application of the described method for the use of multigraphs enabled a more accurate mathematical description of real traffic in communication networks.
A new electronically controlled floating/grounded meminductor emulator based on single MO-VDTA
(2022) Petrovic, Predrag
This paper proposes a circuit configuration to emulate the behaviour of a floating/grounded incremental/decremental flux-controlled meminductor, based on multiple output voltage differencing transconductance amplifier-MO-VDTA. The circuits use two grounded capacitors which benefit from the integrated circuit (the MOS-capacitance can be used instead of the capacitor when the simulator circuits are operated in the high frequency region) and has a single active component matching constraint. The influence of possible non-ideality and parasitic effects was analysed, while the effects of the parasitic are only marginal due to the absence of any passive elements. The designed circuit also possesses the electronic tunability feature, which supports the controllable nature of realized inverse meminductance. The applicability of the proposed emulator has also been shown in neural network applications. The emulation circuit has been verified by executing simulations using CMOS 0.18 μm process technique under SPICE environment.
A New High Precision Power Detector of Complex Voltage Signals
(2015) Petrovic, Predrag
© by Predrag B. Petrović 2015. A current-mode bipolar power detector based on a novel synthesis of translinear loop squarer/divider is presented. The circuits consist of a single multiple-output current controlled current differencing transconductance amplifier (MO-CCCDTA), two current controlled conveyors (CCCII), and one resistor and one capacitor that are both grounded. The errors related to the signal processing and errors bound were investigated and presented in the paper. The PSpice simulation and experimental results are depicted, and agree well with the theoretical anticipation. The measurement results show that the scheme improves the accuracy of the detector to better than 0.04 % and wide operating frequency range from 50 Hz to 10 MHz. The maximum power consumption of the detector is approximately 5.80 mW, at ±1.2 V supply voltages.
A new logarithm methodology of additive weights (LMAW) for multi-criteria decision-making: Application in logistics
(2021) Pamucar, Dragan; Žižović, Mališa; Biswas, Sanjib; Božanić, Darko
Logistics management has been playing a significant role in ensuring competitive growth of industries and nations. This study proposes a new Multi-Criteria Decision-making (MCDM) framework for evaluating operational efficiency of logistics service provider (LSP). We present a case study of comparative analysis of six leading LSPs in India using our proposed framework. We consider three operational metrics such as annual overhead expense (OE), annual fuel consumption (FC) and cost of delay (CoD, two qualitative indicators such as innovativeness (IN) which basically indicates process innovation and average customer rating (CR)and one outcome variable such as turnover (TO) as the criteria for comparative analysis. The result shows that the final ranking is a combined effect of all criteria. However, it is evident that IN largely influences the ranking. We carry out a comparative analysis of the results obtained from our proposed method with that derived by using existing established frameworks. We find that our method provides consistent results; it is more stable and does not suffer from rank reversal problem.
A New Method of Multi-Criteria Analysis for Evaluation and Decision Making by Dominant Criterion
(2019) Žižović M.; Albijanić M.; Jovanovic V.; Žižović, Mališa
© 2019-Vilnius University. This paper introduces a new method for multi-criteria analyses where the failure to meet the dominant criterion of an alternative causes low values for the entire alternative. In this method, the introduction of new alternatives into the multi-criteria model does not affect the existing alternatives in the model. The new method was applied for the rating of ten websites of dental clinics in Serbia, which provide prosthetic services to tourists. The dominant criterion was the amount of information provided by the site.

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