Elektronika ir Elektrotechnika http://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The research journal ELEKTRONIKA IR ELEKTROTECHNIKA publishes previously unpublished manuscripts that will have a high impact in the field of electronics and electrical engineering.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> Title http://eejournal.ktu.lt/index.php/elt/article/view/25313 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 1 1 Editorial Board http://eejournal.ktu.lt/index.php/elt/article/view/25314 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 2 3 Control of Milk Fermentation in Batch Bioreactor http://eejournal.ktu.lt/index.php/elt/article/view/23377 <p>In this paper, modelling and control of a batch bioreactor is studied. A main disadvantage of batch bioreactors compared to other types of bioreactors is their inability to introduce biological or/and chemical substances during operation. Therefore, possibility of bioreactor’s control by means of changing temperature was proposed, analyzed, and implemented. A new supplementary input/output dynamical mathematical model, which considers influence of heating and cooling on a bioprocess, was developed. On a basis of this model, a control system was designed and a method for tuning of the controller was suggested. Results show characteristics, applicability, and advantages of the presented approach.</p> Jozef Ritonja Andreja Gorsek Darja Pecar Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 4 9 10.5755/j01.eie.26.1.23377 An Embedded Controller Application with Regenerative Braking for the Electric Vehicle http://eejournal.ktu.lt/index.php/elt/article/view/25306 <p>Regenerative braking is very important for increasing the total range of an electric vehicle. In this study, an embedded controller, including regenerative braking, is designed and implemented for an electric vehicle. Experimental studies are carried out on an electric vehicle driven by two in-wheel electric motors. In-wheel electric motors are preferred in light electric vehicles, since they are both highly efficient and supports regenerative braking. In our embedded controller application, the in-wheel electric motor is operated in both the motor mode and the regenerative braking mode. The in-wheel electric motor control embedded software is developed in the Matlab/Simulink environment. The developed software is embedded in the DSP STM32F407 microcontroller, which has ARM Cortex-M4 core. The in-wheel electric motor is controlled by a fuzzy logic controller in the motor mode, the in-wheel electric motor - in the regenerative braking mode. Different PWM (Pulse Width Modulation) ratios are applied to the wheel electric motor in the regenerative braking mode. The experimental data are recorded in real-time by transferring to a PC on the electric vehicle. The performance of the study is proven with experimental tests.</p> Yusuf Karabacak Ali Uysal Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 10 17 10.5755/j01.eie.26.1.25306 A New Method for Angular Speed Measurement with Absolute Encoder http://eejournal.ktu.lt/index.php/elt/article/view/25307 <p>The encoders are electromechanical devices that give information about the angular position and the number of turns of the shaft, which they are connected. These devices are divided into digital or analogue according to output types. On digital outputs, the output can be binary coded, gray coded or pulsed. The frequency (M) or period (T) method produces accurate results in pulse-output encoders. However, these methods alone cannot give accurate results in some encoder types, which are saw tooth type encoders that produce analogue outputs in different shapes. In this study, a new method was proposed, which reduces the relative error ratio too much below 1&nbsp;% in an absolute encoder that produces an analogue output ranging from 0&nbsp;V to 5&nbsp;V according to the angular position of the shaft. Unlike in the studies in the literature, M method and Analog Digital Converter (ADC) were used together. Thanks to this proposed method (M + ADC), it is possible to increase the measurement accuracy of the encoders with analogue output in all speed regions.</p> Ramazan Akkaya Fatih Alpaslan Kazan Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 18 22 10.5755/j01.eie.26.1.25307 Prediction of Harvested Energy for Wireless Sensor Node http://eejournal.ktu.lt/index.php/elt/article/view/23807 <p align="justify">Energy harvesting wireless sensor nodes are interesting for the Internet of Things, since they can provide continuous operation by adapting workload not only to the current energy reserves, but to the amount of energy that can be harvested in the future also. We present a multistage day ahead hourly solar energy prediction algorithm. The predictor uses cloud cover and precipitation probability predictions from weather forecast obtained once per day for 24 hours in advance. To compensate for short-term weather changes until the next weather forecast data is obtained, forecast errors of humidity and atmospheric pressure are fed to the fuzzy logic filter. The filter adjusts predictions of cloud cover and precipitation probability, which are applied to the clear-sky radiation model in order to obtain prediction of solar energy. The prediction of solar energy is additionally corrected based on the energy prediction error in the preceding time slot. The results show that the proposed predictor outperforms the state-of-the-art predictors in terms of prediction error. Proposed predictor and state-of-the-art predictors were also evaluated using a simulated wireless sensor node with the simple energy management algorithm, where the proposed predictor was the most efficient at maintaining energy neutrality.</p> Strahinja Jankovic Lazar Saranovac Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 23 31 10.5755/j01.eie.26.1.23807 Sensorless Control of a PMSM Drive Using EKF for Wide Speed Range Supplied by MPPT Based Solar PV System http://eejournal.ktu.lt/index.php/elt/article/view/25308 <p>In photovoltaic (PV) applications, employing Surface-Mounted Permanent Magnet Synchronous Motor (SMPMSM) can be a suitable option, especially for solar pumping and Heating, Ventilation, and Air Conditioning (HVAC) applications. However, when the motor loads are supplied from varying and limited energy sources, such as solar PV, it is vital to determine operating behavior and provide a stable operation for a wide range of operating conditions. In this study, the operating stability of Permanent Magnet Synchronous Motor (PMSM) was improved by sensorless Field Oriented Control (FOC) based on Extended Kalman Filter (EKF). In order to achieve optimal operation of the PV system under various meteorological conditions and load variations, an incremental conductance approach based maximum power point tracking (MPPT) system was introduced. For estimation of the speed of PMSM in wide speed range, instead of using a hybrid estimation strategy, fixed d-axis current with EKF was applied to the low-speed regions of SMPMSM, while in the medium and high speed regions, the d-axis current was set to zero. The major contributions of this paper are to reduce complexity of the control method and testing the method in a photovoltaic system with MPPT operation. The complete system was modeled in a Matlab/Simulink environment and simulation results are shown according to a wide range of operating conditions.</p> Abbas Mahmood Oghor Anwer Fuad Alhaj Omar Hale Bakir Ahmet Afsin Kulaksiz Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 32 39 10.5755/j01.eie.26.1.25308 Sparse FIR Filter Design Based on Signomial Programming http://eejournal.ktu.lt/index.php/elt/article/view/23560 <p>The goal of sparse FIR filter design is to minimize the number of nonzero filter coefficients, while keeping its frequency response within specified boundaries. Such a design can be formally expressed via minimization of <em>l</em><sub>0</sub>-norm of filter’s impulse response. Unfortunately, the corresponding minimization problem has combinatorial complexity. Therefore, many design methods are developed, which solve the problem approximately, or which solve the approximate problem exactly. In this paper, we propose an approach, which is based on the approximation of the <em>l</em><sub>0</sub>-norm by an <em>l<sub>p</sub></em>-norm with 0 &lt; <em>p</em> &lt; 1. We minimize the <em>l<sub>p</sub></em>-norm using recently developed method for signomial programming (SGP). Our design starts with forming a SGP problem that describes filter specifications. The optimum solution of the problem is then found by using iterative procedure, which solves a geometric program in each iteration. The filters whose magnitude responses are constrained in minimax sense are considered. The design examples are provided illustrating that the proposed method, in most cases, results in filters with higher sparsity than those of the filters obtained by recently published methods.</p> Maja Jurisic Bellotti Mladen Vucic Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-16 2020-02-16 26 1 40 45 10.5755/j01.eie.26.1.23560 Extraction of Novel Features Based on Histograms of MFCCs Used in Emotion Classification from Generated Original Speech Dataset http://eejournal.ktu.lt/index.php/elt/article/view/25309 <p>This paper introduces two significant contributions: one is a new feature based on histograms of MFCC (Mel-Frequency Cepstral Coefficients) extracted from the audio files that can be used in emotion classification from speech signals, and the other – our new multi-lingual and multi-personal speech database, which has three emotions. In this study, Berlin Database (BD) (in German) and our custom PAU database (in English) created from YouTube videos and popular TV shows are employed to train and evaluate the test results. Experimental results show that our proposed features lead to better classification of results than the current state-of-the-art approaches with Support Vector Machine (SVM) from the literature. Thanks to our novel feature, this study can outperform a number of MFCC features and SVM classifier based studies, including recent researches. Due to the lack of our novel feature based approaches, one of the most common MFCC and SVM framework is implemented and one of the most common database Berlin DB&nbsp; is used to compare our novel approach with these kind of approaches.</p> Muhammet Pakyurek Mahir Atmis Selman Kulac Umut Uludag Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 46 51 10.5755/j01.eie.26.1.25309 A Novel Random Number Generator Based on Fractional Order Chaotic Chua System http://eejournal.ktu.lt/index.php/elt/article/view/25310 <p>One of the practical applications of chaotic systems is the design of a random number generator. In the literature, generally random number generators are designed using discrete time chaotic systems. The reason for the use of the discrete time chaotic systems in the design architecture is that the latter have a simpler structure than the continuous time chaotic systems. In order to observe chaos in continuous time systems, the system must have at least three degrees. It is shown that for fractional order chaotic systems chaos can be observed even in a lower system degree. The aim of this study is to develop a random number generator using a fractional order chaotic Chua system. The proposed generator is analysed using various randomness tests. The analysis results show that the proposed generator passes the random requirements successfully. On the one hand, this study is important because it demonstrates the practical application of fractional order chaotic systems. On the other hand, it provides an alternative to designs based on discrete time chaotic systems.</p> Fatih Ozkaynak Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 52 57 10.5755/j01.eie.26.1.25310 A Practical Method for Detecting Fluff Quality of Fabric Surface Using Optimal Sensing http://eejournal.ktu.lt/index.php/elt/article/view/24221 <p>The raising process has been widely used in manufacturing fabric productions. After raising the surface of the fabric, productions are covered with a fluff layer. The quality of the fabric surface is often valuated by the fluffing type. In order to objectively assess the fluff quality of the fabric surface, an optimal sensing method is proposed in this paper. The fluff contour image was firstly collected by the light-cut imaging device. Then, the fluff region was segmented by the adaptive image segmentation method, the contour coordinates of the fabric were extracted using the freeman chain code and constructed in the form of the binary image. Lastly, a back-propagation neural network (BPNN) was used to learn the relationship between the contour coordinates and the fluff quality. On this basis, a practical fabric fluff detection platform was developed based on the optimal sensing technique. Experimental tests were conducted to evaluate the performance of the proposed method in detecting the fluff quality with four different colours and different fluffing processes. Furthermore, the actual fabric inspection was carried out. The detection correct rate can reach 94.17&nbsp;%, which can meet the practical production requirement.</p> Shoufeng Jin Qiangqiang Lin Yu Bie Qiurui Ma Zhixiong Li Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 58 62 10.5755/j01.eie.26.1.24221 A New Object Tracking Framework for Interest Point Based Feature Extraction Algorithms http://eejournal.ktu.lt/index.php/elt/article/view/25311 <p>This paper presents a novel object tracking framework for interest point based feature extracting algorithms. The proposed framework uses the feature extracting algorithm without making any changes and it relies on outlier detection, object modelling, and object tracking. At first, the keypoints are extracted by using a feature extraction algorithm. Then, incorrect keypoint matches are detected by the DBScan algorithm. The second step of our tracking framework is object modelling. The object model is defined as a bounding box. The box model has six points and each of these points has its own Gaussian model. Finally, the Gaussian model is performed for object tracking. In object tracking, the old five values are retained to detect incorrect position information. Thus, while the object movements are softened, the instant deviations are eliminated also. Our interest point based object tracking framework (IPBOT) works with any interest point based feature extracting algorithm. Thus, a new algorithm can be added to the object tracking framework with a short integration process. The experiment results show that the proposed tracker significantly improves the success rate of the object tracking.</p> Zafer Guler Ahmet Cinar Erdal Ozbay Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 63 71 10.5755/j01.eie.26.1.25311 Performance Analysis of Edge Computing in IoT http://eejournal.ktu.lt/index.php/elt/article/view/23235 <p>Upcoming 5G technology and the demand for near real-time response services raise the need for optimizing current IoT solutions. The aim of this paper is to model and execute the performance analysis of network structures suitable for Edge Computing in IoT. The prior research into different topology and parameter sets have not provided sufficient clarity, on which parameters had a considerable impact on overall system performance; therefore, repetitive simulations were performed to express dispersion of alternating values, as well as determining its confidence intervals. The paper presents Edge Computing service simulation setup on known and newly derived network topologies with different complexity varying network bandwidth and network delay parameters. The experimental investigation has revealed that the IoT configuration network is more sensitive to network topology, while the Internet configuration is more sensitive to network parameters. The discussion on the results received debates possible causes of performance differences in network parameters and device configurations, the comparison to similar state-of-the-art research results has also been presented. Finally, conclusions with recommendations based on the results acquired have been provided.</p> Julius Skirelis Dalius Navakauskas Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 72 77 10.5755/j01.eie.26.1.23235 Storage and Communication Security in Cloud Computing Using a Homomorphic Encryption Scheme Based Weil Pairing http://eejournal.ktu.lt/index.php/elt/article/view/25312 <p>With introduction of smart things into our lives, cloud computing is used in many different areas and changes the communication method. However, cloud computing should guarantee the complete security assurance in terms of privacy protection, confidentiality, and integrity. In this paper, a Homomorphic Encryption Scheme based on Elliptic Curve Cryptography (HES-ECC) is proposed for secure data transfer and storage. The scheme stores the data in the cloud after encrypting them. While calculations, such as addition or multiplication, are applied to encrypted data on cloud, these calculations are transmitted to the original data without any decryption process. Thus, the cloud server has only ability of accessing the encrypted data for performing the required computations and for fulfilling requested actions by the user. Hence, storage and transmission security of data are ensured. The proposed public key HES-ECC is designed using modified Weil-pairing for encryption and additional homomorphic property. HES-ECC also uses bilinear pairing for multiplicative homomorphic property. Security of encryption scheme and its homomorphic aspects are based on the hardness of Elliptic Curve Discrete Logarithm Problem (ECDLP), Weil Diffie-Hellman Problem (WDHP), and Bilinear Diffie-Helman Problem (BDHP).</p> Demet Cidem Dogan Huseyin Altindis Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 78 83 10.5755/j01.eie.26.1.25312 Reviewers http://eejournal.ktu.lt/index.php/elt/article/view/25315 Elektronika ir Elektrotechnika Copyright (c) 2020 Elektronika ir Elektrotechnika 2020-02-17 2020-02-17 26 1 85 85