IJEEC - INTERNATIONAL JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTING
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Published By National And University Library Of The Republic Of Srpska

2566-3682

Author(s):  
Ilja Stanišević ◽  
Mlađen Vićentić ◽  
Slobodan Obradović

In order to select database managmeent tool (i.e., DBMS) for information system developed for Valjevo Business School, testing of two available options (i.e. MS SQL and MySQL) was performed. Instead of using available benchmark software, simple software to test features relevant to the system was developed. The tool was developed using the same technology as the school’s information system and was designed to test only relevant features. The aim was not to provide general evaluation of the tested DBMS but to evaluate specific features and to determine option more relevant for the specific situation and environment. This paper describes applied methodology and displays realized results. In the first part of the paper the technical and organizational foundation is described. Then there is a description of possible solutions to the problem with the justification of the applied methodology. The first step in realization of the research was to determine testing domain and investigation framework. The features and requirements of the technical environment are shown. The conceptual design and features as well as user interface and available options of the testing tool realized for the purpose of this research are described. Finally the results and conclusions are presented.


Author(s):  
Mladen Banjanin

This paper deals with the experimental, analytical and numerical analysis of voltage distribution along the cap-and-pin insulators. Five different insulators strings are analyzed, consisting of two, three, four, five and six cap-and-pin U40BL glass disc insulators. Experimental measurements are performed in the high voltage laboratory at the Faculty of Electrical Engineering East Sarajevo. Measurement of the voltage distribution along the disc insulators is performed by using measuring sphere gap. Analytical calculations are performed by using mathematical model which considers parasite self-capacitances of disc insulators, as well as their parasite capacitances to the earth and to the phase conductor. Calculations of the parasite capacitances values are performed and optimum values which lead to the minimum difference between measured and calculated results are suggested. Numerical analyses of the non-linear voltage distribution are performed by using electrostatic field model in software Comsol Multyphisics. 2D axisymmetric models of the cap-and-pin insulators are developed. Despite the measuring configuration is not suitable for numerical analysis, relatively good agreement between the measured results and results calculated by using specialized software are achieved.


Author(s):  
Verica Marinković-Nedelicki ◽  
Branislav Pavić ◽  
Jovan Radivojević ◽  
Predrag Petrović ◽  
Aleksandar Lebl

The radio system for high frequency spectrum monitoring and signal processing used in direction finding is presented in this paper. This main function is realized using 6-channel HF radio signal receiver. The high degree of flexibility is achieved by the application of antenna multicoupler unit which allows that signals from several antennas may be processed in the system. The system signal processing especially in the demodulator is based on the most modern components of software defined radio. The system is completely developed in the Institute IRITEL applying commercial components wherever such an approach may fulfill the expected performances. The realized development is highly multidisciplinary and specific, especially HF radio signal receiver and the structure of its modules (local oscillator, RF/IF receiver subsystem, demodulator and control block) which is presented in the paper in more details. User handling is simple over intuitive user interface and system functional parameters may be easily changed. Special attention in the paper is devoted to this interface and software control procedures. The designed electrical characteristics are verified by comprehensive set of measurements according to military specifications both for HF radio signal receiver and antenna multicoupler unit and these characteristics are illustrated by several examples. The system is approved for the application in real conditions.


Author(s):  
M. S Saliu ◽  
I. J Umoh ◽  
B.O. Sadiq ◽  
M.O Momoh

This paper presents an age-aware adaptive routing for Odd-Even (OE) turn model. As packets traverse from source to destination node, their paths are defined by a given routing algorithm. For a selected routing algorithm, an efficient arbitration technique is crucial to sharing critical Network-on-Chip resources. Arbitration techniques provide high degree of local fairness from each router point of view. However, there is delay of a packet with a longer path between the source and destination nodes. In order to address this challenge an age-based arbitration technique is hereby proposed for adaptive routing with OE turn model. The age-aware adaptive routing uses an age-based arbitration technique that gives priority to oldest packet. The performance of the developed age-aware adaptive routing was evaluated using different synthetic traffic at different Packet Injection Rates (PIRs). Results were compared with the result obtained on fair arbitration technique for adaptive routing using average latency and throughput as performance metrics. The result indicated that the age-aware adaptive routing has 2.73%, 6.63 %,5.4% and 4.5 % reduction in latency under random, transpose 1 transpose 2 and bit reversal traffic patterns respectively when compared to fair arbitration adaptive routing with OE turn model. For throughput the results indicated that the age-aware adaptive routing with OE turn model has 14.22%, 13%.12% and 19% increase in throughput under random, transpose 1 transpose 2 and bit reversal traffic patterns respectively when compared to fair arbitration adaptive routing with OE turn model.


Author(s):  
Darija Čarapić ◽  
Mirjana Maksimović

The rapid, reliable, and secure data transmission in everyday life and numerous applications is one of the crucial demands of modern society. Mobile wireless communications have advanced significantly in recent decades. From the first (1G) to fifth-generation (5G) of mobile communications, the realization of fast and secure communication has always been challenging as data transfer happens in an imperfect channel environment where noise due to amplification, distortion, and other impairments is present. Channel coding is key to establishing fast communication with low error probability, implying that choosing the proper channel coding scheme is a challenging and crucial task. Higher flexibility and reliability, and low computational complexity, latency, and costs are desired coding technique characteristics. This paper focuses on two 5G channel coding techniques, Low-Density Parity-Check (LDPC) and Polar codes. These codes have been examined in the case of variable message sizes and for a wide range of code rates. In addition, different Polar decoding algorithms have been investigated. Simulations results have confirmed that there is no single channel coding scheme able to meet all 5G requirements as well as the superiorities of LDPC codes in case of long messages and Polar codes for short messages. The ability to support a wide range of code lengths and code rates and excellent Bit Error Rate (BER) performances, justify the utilization of LDPC and Polar codes in 5G communication systems.


Author(s):  
Čedomir Milosavljević ◽  
Branislava Peruničić-Draženović ◽  
Senad Huseinbegović ◽  
Boban Veselić ◽  
Milutin P. Petronijević

Modern control techniques of electrical drives (EDs) use robust control algorithms. One of such algorithms is variable structure control (VSC) with sliding mode (SM). SM control needs more information on the controlled plant than the conventional PI(D) control. Valid mathematical model of the controlled plant is necessary for the SM controller design. Generalized mathematical model of two-phase electrical machine and its adaptation to direct current (DC) and induction motor (IM) are given in this paper, employed in the cascade control structure. Also, the basic SM control theory and discrete-time controller design approach, developed by the authors, are given. Finally, experimentally realized examples of speed and position control of DC and IM are given as an illustration of the efficiency of the promoted EDs controller design via discrete-time VSC.


Author(s):  
Miroslav Kostadinovic ◽  
Aleksandar Stjepanovic ◽  
Goran Kuzmic ◽  
Mirko Stojcic ◽  
Tanja Kostadinovic

The topology of WirelessHART network is changeable since a number of dynamic devices change, and all that requires a reorganization of the network, as well as finding new ways of routing data. Devices can fall out of the network due to destruction, failure, reduction or loss of electricity. On the other hand, it is possible to “refresh” the network with new devices and thus completely change the topology of the newly created network. This research analize the quality of data transferring in a WirelessHART network using two network topologies: Extended star network and Mesh network. The aim of this paper is to determine which network topology provides better quality of data transferring in a WirelessHART network on the basis of signal latency and Received Signal Strength Indicator (RSSI). To achieve this, experiments are performed using the equipment by the manufacturer Emerson Process Management: Gateway 1420, TT 648 and PT 3051 for the implementation of the network, as well as software tools for configuration, planning and management of wireless industrial networks, AMS Wireless SNAP-ON and AMS Intelligent Device Manager. The research results show several advantages of applying Mesh topology in a WirelessHART network: it is almost impossible to interrupt communication between devices in the network; there does not have to be optical visibility between the network devices; ease of installation and deinstallation; low application cost compared to Extended star network.


Author(s):  
Momčilo Amović ◽  
Vladimir Vujović ◽  
Snježana Milinković

From the 18th century, the Industrial Revolutions led to the creation of a base for the development and progress of civilization and business. Different business models that relied on the new trends defined by the industrial revolutions significantly transformed the ecosystems of companies. This resulted in the accelerated development and entrance into the digital age, followed by the digitization of the environment and establishing a new system of values. Information and communication technologies are the backbone of the development and mapping of the physical domain into cyber-physical, leading to the emergence of new processes, knowledge, and skills that have been established in the context of Digital Transformation and the digital era. The key part of Digital transformation process is the Smart Systems concept, which is present in almost all industries and domains. Smart Agriculture is one of the most common applications of Smart Systems solutions. It aims to answer important questions regarding food production while, at the same time, taking care of the preservation of the environment, the health of the population and global development. In this paper, the key concepts of the digital transformation and smart systems are presented. In addition, the design and development of the GoGrow, commercial solution for smart agriculture is described.


Author(s):  
Nikola Ostojić ◽  
Čedomir Zeljković ◽  
Predrag Mršić

Bifacial photovoltaic modules have gained increasing attention in the last decade due to their potential to achieve higher annual energy yield in comparison to conventional monofacial modules. Since the higher energy production is also accompanied by higher investment costs, it is necessary to conduct a careful techno-economic analysis in order to provide the investors an answer about their accurate cost efficiency. The achievable energy output of a bifacial photovoltaic power plant is influenced by many factors such as module geometry, row spacing, orientation of the modules and ground albedo. Since the methodology for prediction of the energy yield has not yet been standardized, the main target of this paper was to create one version of a comprehensive standalone energy calculator that would serve as a useful performance assessment tool for designers and investors. The developed software tool was tested on several characteristic scenarios and the obtained results were compared with the results provided by two freely available online calculators.


Author(s):  
Branislava Cvijetic ◽  
Zaharije Radivojevic

Institutions that provide official statistics tend to use external data sources such as administrative data sources besides regular statistical surveys. In addition to the mentioned data sources, Big Data became recognized as a new data source for the provider of official statistics. Classification of textual data is one of the elementary tasks for the provider of official statistics, regardless of data sources. In this paper, application of traditional machine learning algorithms, Multinomial Naive Bayes and Support Vector Machine, for the classification of advertised jobs according to ISCO-08, has been presented. The paper presents the methods of collecting data on advertised jobs from four websites and procedures for creating a multilingual dataset. There are different types of text preprocessing, such as converting uppercase letters into lowercase letters, stopword removal, punctuation mark removal, lemmatization, correction of commonly misspelled words, and reduction of replicated characters. We hypothesized that the application of different combinations of preprocessing methods influenced the text classification results. Two experiments had conducted to test the hypothesis. Both experiments results showed that using the Support Vector Machine algorithm on a created dataset gives better results than Multinomial Naive Bayes. Performed experiments showed that the proposed algorithms gave a good performance with an overall accuracy of up to 90% but with different accuracy for individual classes due to an imbalanced dataset.


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