Elektronika ir Elektrotechnika https://eejournal.ktu.lt/index.php/elt <div>ELEKTRONIKA IR ELEKTROTECHNIKA is&nbsp;a peer-reviewed bimonthly research journal of Kaunas University of Technology.</div> <p>The research journal ELEKTRONIKA IR ELEKTROTECHNIKA publishes previously unpublished manuscripts that will have a high impact in the field of electronics and electrical engineering. It targets not only certain field specialists, but the wider public also.</p> Kaunas University of Technology en-US Elektronika ir Elektrotechnika 1392-1215 <p>Authors retain copyright and grant the journal the right of the first publication with the paper simultaneously licensed under the <a href="https://creativecommons.org/licenses/by/4.0/" target="_blank" rel="noopener">Creative Commons Attribution 4.0&nbsp;(CC BY 4.0)</a> licence.</p> <p>Authors are allowed to enter into separate, additional contractual arrangements for the non-exclusive distribution of the paper published in the journal with an acknowledgement of the initial publication in the journal.</p> <p>Copyright terms are indicated in the Republic of Lithuania Law on <a href="https://e-seimas.lrs.lt/portal/legalAct/lt/TAD/5f13b560b2b511e59010bea026bdb259?jfwid=9tq147ogj" target="_blank" rel="noopener">Copyright and Related Rights, Articles 4-37</a>.</p> Reviewers https://eejournal.ktu.lt/index.php/elt/article/view/28153 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 67 67 Title https://eejournal.ktu.lt/index.php/elt/article/view/28151 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 1 1 Editorial Board https://eejournal.ktu.lt/index.php/elt/article/view/28152 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 2 3 An Introduction to Cybersecurity at Physical Layer: Obstacles at Radio Channel to Mitigate Hackers’ Chance https://eejournal.ktu.lt/index.php/elt/article/view/28006 <p>Cybersecurity commonly focuses on higher layers of Open Systems Interconnection (OSI) model, as it is a discipline associated to Computer Science. However, physical layer is the front line of the defence of a system against external attacks, and Electrical Engineering, concretely Radiofrequency Engineering, can provide tools to reinforce radio networks also in terms of information security. This paper analyses different techniques related to site shielding. From hard traditional shielding, similar to Faraday cages, to different soft shielding solutions as vegetation fences and frequency selective surfaces (FSS), the variety of solutions is broad and would be useful in actual deployments. Finally, Building Information Modelling (BIM) appears as an interesting tool that could be incorporated along the design and construction of an office building to improve the electromagnetic behaviour, and subsequently the cybersecurity issues of the communication networks hosted by the building itself.</p> Inigo Cuinas Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 58 65 10.5755/j01.eie.26.6.28006 Approach to Choose of Optimal Number of Turns in Planar Spiral Coils for Systems of Wireless Power Transmission https://eejournal.ktu.lt/index.php/elt/article/view/26181 <p>Correct choice of coil parameters for resonant circuits in inductive power transmission systems is a relevant problem, as it significantly influences the efficiency and transmitted power in the systems and provides for optimization of these parameters. This paper presents a methodology of calculation of geometrical and electrical parameters and approach to choose the optimal number of turns in planar coils used in the wireless power transmission (WPT) system with parallel resonant circuit. Formulas are derived for calculation of active resistance and inductance of the coil, normalized to the specified design parameters of the coil. Connection is made between the design and electrical parameters of the coil, which allows choosing the optimal number of turns according to different criteria and guard conditions. The examples of practical use of the chosen approach with transmitting and receiving coils of WPT system are presented. The obtained results show that efficiency and transmitted power in the system are higher when using the coils with the calculated number of turns. The proposed approach may be used in selection of optimal design of loop coils in systems with fixed frequency, and in systems, whose operational frequency depends on the parameters of the resonant circuit.</p> Konstantin Krestovnikov Ekaterina Cherskikh Аleksandr Bykov Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 17 24 10.5755/j01.eie.26.6.26181 Resource Allocation Techniques in Cloud Computing: A Review and Future Directions https://eejournal.ktu.lt/index.php/elt/article/view/25865 <p>Cloud computing has become a very important computing model to process data and execute computationally concentrated applications in pay-per-use method. Resource allocation is a process in which the resources are allocated to consumers by cloud providers based on their flexible requirements. As the data is expanding every day, allocating resources efficiently according to the consumer demand has also become very important, keeping Service Level Agreement (SLA) between service providers and consumers in prospect. This task of resource allocation becomes more challenging due to finite available resources and increasing consumer demands. Therefore, many unique models and techniques have been proposed to allocate resources efficiently. In the light of the uniqueness of the models and techniques, the main aim of the resource allocation is to limit the overhead/expenses associated with it. This research aims to present a comprehensive, structured literature review on different aspects of resource allocation in cloud computing, including strategic, target resources, optimization, scheduling and power. More than 50 articles, between year 2007 and 2019, related to resource allocation in cloud computing have been shortlisted through a structured mechanism and they are reviewed under clearly defined objectives. It presents a topical taxonomy of resource allocation dimensions, and articles under each category are discussed and analysed. Lastly, salient future directions in this area are discussed.</p> Muhammad Faraz Manzoor Adnan Abid Muhammad Shoaib Farooq Naeem A. Nawaz Uzma Farooq Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 40 51 10.5755/j01.eie.26.6.25865 A New Classification Approach with Deep Mask R-CNN for Synthetic Aperture Radar Image Segmentation https://eejournal.ktu.lt/index.php/elt/article/view/25849 <p>In this paper, a hybrid classification approach which is combined with a more deep mask region-convolutional neural network and sparsity driven despeckling algorithm is proposed for synthetic aperture radar (SAR) image segmentation instead of the classical segmentation methods. In satellite technology, synthetic aperture radar images are strongly used for a lot of areas, such as evaluating air conditions, determining agricultural fields, climatic changes, and as a target in the military. Synthetic aperture radar images must be segmented to each meaningful point in the image for a quality segmentation process. In contrast, synthetic aperture radar images have a lot of noisy speckles and these speckles should be also reduced for a quality segmentation. Current studies show that deep learning techniques are widely used for segmentation methods. High accuracy and fast results can be obtained with deep learning techniques for image segmentation. Mask region-convolutional neural network can not only separate each meaningful field in the image, but it can also generate a high accuracy prediction for each meaningful field of synthetic aperture radar images. The study shows that smoothed SAR images can be classified as multiple regions with deep neural networks.</p> Ridvan Yayla Baha Sen Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 52 57 10.5755/j01.eie.26.6.25849 Continuity Detection Method in Binary Image Signal https://eejournal.ktu.lt/index.php/elt/article/view/25770 <p>This paper is focused on a description of a new method of detecting continuities in a binary image. The detecting method is called “Binary Large Object” (BLOB). A new algorithm with other elementary parameters, as processing speed and memory capability, are described here. The developed BLOB method with described algorithms is implemented in MATLAB. The simulation of the algorithms is tested in different conditions, with the time dependences determination. The research results of the computing time or the BLOB memory demand during computation are presented as well. The developed BLOB method is usable as one of the elementary image processing methods of the field detection dependencies in the images, like pattern recognition or OCR algorithm.</p> Radim Hercik Zdenek Machacek Jiri Koziorek Jan Vanus Miroslav Schneider Wojciech Walendziuk Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 4 9 10.5755/j01.eie.26.6.25770 Redundant and Flexible Pseudorandom Optical Rotary Encoder https://eejournal.ktu.lt/index.php/elt/article/view/25476 <p>Optical encoders are mainly used in modern motion servo systems for high-resolution and reliable position and velocity feedback. Pseudorandom optical rotary encoders are single-track and use a serial pseudorandom binary code to measure absolute position. The realization and analysis of such a rotary encoder with advanced code scanning and error detection techniques, as well as an improved redundancy in operation, are presented. A presented serial code reading solution uses two phase-shifted code tracks and two optical encoder modules. So, the realized encoder, hybrid in nature, provides “output on demand” and more or less reliable position information using very efficient error checking. Compared to a standard absolute encoder, this encoder requires a smaller code disc, facilitates installation, has greater flexibility in operation, and is less sensitive to external influences.</p> Goran S. Miljkovic Dragan B. Denic Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 10 16 10.5755/j01.eie.26.6.25476 A Novel Pre-Synchronization Control for Grid Connection of Virtual Synchronous Generator https://eejournal.ktu.lt/index.php/elt/article/view/25874 <p>The virtual synchronous generator (VSG) introduces rotational inertia and damping through the droop control to take part in frequency regulation of the grid. By building the VSG model, the VSG controller, including both the frequency controller and the excitation controller, are analysed and designed. The analysis shows that the large phase difference Δθ between the VSG voltage and the grid voltage at the grid-tied moment may produce large power and damage the VSG. The proposed pre-synchronization control minimizes the phase difference, which is implemented by replacing Δθ with sinΔθ to avoid any step change from Δθ. The proposed method is able to simplify control, shorten pre-synchronization tracking time, and achieve high accuracy without a phase-lock loop. The built 12 kW VSG simulation and prototype verify the theoretical analysis, the proposed control and its associated design.</p> Xuhai Chen Yiwang Zhang Jiqing Dong Xingkui Mao Jiaqiao Chen Buyin Wen Zhe Zhang Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 25 31 10.5755/j01.eie.26.6.25874 Multi-Area Load Frequency Control of Hydro-Thermal-Wind Power Based on Improved Grey Wolf Optimization Algorithm https://eejournal.ktu.lt/index.php/elt/article/view/27484 <p>The mathematical model of load frequency control is established in the interconnected power system of hydro, thermal, and wind for solving the problem of frequency instability in this paper. Besides, the improved grey wolf optimization algorithm (GWO) is presented based on the offspring grey wolf optimizer (OGWO) search strategy to handle local convergence for the GWO algorithm in the later stage. The experimental results show that the improved grey wolf algorithm has a superior optimization ability for the standard test function. The traditional proportional integral derivative (PID) controller cannot track the random disturbance of wind power in the hydro, thermal, and wind interconnected power grid. However, the proposed OGWO dynamically adjusts the PID controller control parameters to follow the wind power random disturbance, regional frequency deviation, and tie-line power deviation.</p> Fannie Kong Jinfang Li Daliang Yang Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-12-18 2020-12-18 26 6 32 39 10.5755/j01.eie.26.6.27484