Balkan Journal of Electrical and Computer Engineering

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ISSN : 2147284X
Total articles ≅ 221
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Sedat Bilgili, Alper Kamil Demir
Balkan Journal of Electrical and Computer Engineering, Volume 8, pp 154-163; doi:10.17694/bajece.644104

Abstract:
It is expected that almost every day electronic devices will be connected to the existing internet infrastructure in the context of Internet of Things (IoT). These devices will enable to sense and actuate the physical world. It is foreseen that miniaturized e-health devices will enable monitoring vital health of patients. There exist some studies on networking these e-health devices within the Internet. In this realm, several network protocols are being standardized. 6LoWPAN of IETF is one of these efforts where some set of protocols can be stacked over IEEE 802.15.4 radio. However, it is not clear that which ideal protocol stack for transmission of health data can be adopted well. The novelty of this work is that we studied determination of ideal protocol stack for transmitting health data over 6LoWPAN IoT networks. So then, we carried extensive simulations over Cooja simulator. The compelling results are presented in this work. The results show that 6LoWPAN IoT health networks can be used to serve vital health data of patients.
Ömer Akgün, Aydın Akan, Ozgur Yilmaz
Balkan Journal of Electrical and Computer Engineering, Volume 8, pp 142-146; doi:10.17694/bajece.679926

Abstract:
Amyotrophic lateral sclerosis (ALS) disease, also known as motor neuron disease, is a disease resulting from loss of motor nerve cells in the spinal cord and brain stem region at central nervous system. Researchers can’t find the reason of ALS for certain, however there are a wide variety of risk factors in respect of this disease. This disease has more than one risk factor. Researchers believe that it is resulted from a virus which leads to abnormality in immune system, spoils the structure of DNA and functioning of enzyme system, exhibiting neurotoxic properties. The signals coming to a single arm or leg muscle from upper and lower motor neurons are highly determinative in diagnosis of the disease, although there is not a specific test for diagnosing the ALS disease for certain. Doctors still conduct many tests even though the main symptoms of ALS are the signals coming to muscles. The developments related to gait analysis are used an auxiliary factor in diagnosis and analysis of ALS diseases. In this study, gait signals from control individuals and ALS diseases have been recorded by means of sensors sensitive to the strength under the foot. These signals’ time-amplitude, amplitude spectrum, phase spectrum, average value and variance changes have been analysed. As a result of these inspections, differences of ALS signals from control signals have been identified.
Işıl Karabey Aksakalli, Nur Hüseyin Kaplan, Uğur Kiliç, Işın Erer
Balkan Journal of Electrical and Computer Engineering pp 114-120; doi:10.17694/bajece.651435

Abstract:
Digital image processing methods have a wide area of usage and their complexity is increasing, as well as the tampering methods. A widely used tampering method is copy-move forgery. In this study, a hybrid method combining the DCT and Bilateral filtering is developed. In this method, first overlapping blocks are obtained from the input image. Then, bilateral filtering and DCT of these blocks are multiplied to obtain the refined block features. The block features are scanned by a zig-zag process followed by a lexicographic sorting. Finally, a similarity detection by a predetermined threshold parameter is applied to detect the forgery. Both visual and quantitative results demonstrated that the proposed method can determine the copy-move forgery regions.
Mehmet Yilmaz, Muhammedfatih Corapsiz, Muhammed Reşit Çorapsiz
Balkan Journal of Electrical and Computer Engineering pp 127-134; doi:10.17694/bajece.660025

Abstract:
In today's energy systems, many equipment operate with Direct Current (DC) voltage. However, it is not always possible to obtain the voltage level required for the operation of these equipment from standard power supplies. For this reason DC-DC converters are used to achieve the desired voltage values for equipment with different DC voltage levels. These converters are divided into three general categories, named Buck, Boost and Buck-Boost. The most preferred converter is the Cuk converter with low output ripple voltage, which can operate in both buck and boost modes. In this study, a detailed analysis of the Cuk converter, which is frequently used in Photovoltaic (PV) Panels was performed and different control methods of the output voltage were proposed. While performing this analysis, the dynamic model of the Cuk converter was created in which, Proportional-Integral (PI) and Fuzzy Logic (FL) are used to control the output voltage of the Cuk converter. The performances of both controllers were compared with respect to performance parameters such as steady state error, settling time and rise time. When the results obtained were evaluated as a whole, it was observed that FLC achieved the desired reference with less rise and settling time. In this study, modeling and controller applications of Cuk converter are realized by using MATLAB / SIMULINK program
Egemen Belge, Hızır Kaan Kaba, Ahmet Parlak, Aytaç Altan, Rifat Hacioğlu
Balkan Journal of Electrical and Computer Engineering pp 121-126; doi:10.17694/bajece.654499

Abstract:
Modeling of unmanned aerial vehicle (UAV) with system identification is very important in terms of its model-based effective control. The modeling of UAV is required for aircraft crashes, analyzing autonomous aircrafts, preventing external disturbances, pre-flight analysis. However, since UAV has nonlinear inherent dynamics including inherent chaoticity and fractality, it becomes difficult to obtain a mathematical model under external disturbance. In this study, some of the inherent nonlinear dynamics of UAV are linearized and the model of UAV is obtained by system identification approaches under external disturbance. The linearized lateral dynamics of a fixed wing UAV is used in this study. Further, the flight motion equations applied to fixed wing UAV have been utilized for obtaining the coefficients of lateral model for straight and level flight. The roll angles are calculated using transfer functions for aileron, rudder and deflections inputs. The autoregressive exogenous (ARX), autoregressive moving average with exogenous (ARMAX) and output error (OE) parametric system identification approaches are performed to estimate UAV lateral dynamic system response as using empirical input-output data sets. The accuracy of parametric model estimation and model degrees are compared for different external disturbance effects.
Pinar Arikan, Selami Balci, Funda Battal
Balkan Journal of Electrical and Computer Engineering pp 135-141; doi:10.17694/bajece.664044

Abstract:
The electromagnetic behavior of the inductors used as passive circuit elements directly affects the electrical and mechanical performance of the power electronics circuits. In general, when using inductor core structures with or without airgap in the classical design process, the dynamic effects of the inductance value are not considered in the design stage. However, the inductance value may change during the operation of the circuit due to electrical and magnetic parameters of the inductor, and this change is called roll-off value of the inductance. In this study, the roll-off value has been measured graphically and numerically based on mechanical parameters (such as air-gap length) and electrical parameters (such as winding turns and DC current amplitude) for an air-gapped ferrite E core designed with FEA software. Thus, not only the inductance value calculated in the design stage but also the roll-off value during the operation of the circuit has been reported with the parametric simulation studies.
Dincer Gokcen, Mehmet Akif Çelik, Fatih Emre Aydos
Balkan Journal of Electrical and Computer Engineering, Volume 8, pp 186-192; doi:10.17694/bajece.585798

Abstract:
This study introduces the design of a practical three-stage operational amplifier (op-amp) using nested Miller compensation, particularly for piezoelectric actuators. Driving a piezoelectric actuator represents a challenge in amplifier design due to its large capacitive nature. A stable piezo driver needs to be free of oscillations and phase lag. Direct feedback compensation using a conventional Miller capacitor is an effective method as long as the capacitance of the load is considerably close to the value of the Miller capacitor. However, using a large capacitor causes a decrease in the slew rate and gain bandwidth. To avoid this, our design focused on the utilization of nested Miller compensation technique. A prototype of the design working at 100V peak to peak voltage (V pp ) is implemented using commercial off-the-shelf (COTS) components. The measurements show the successful driving capability and step-response of the op-amp design. In the design, Widlar current source is also utilized for thermal stability and short circuit protection. According to simulation results, the proposed op-amp has a slew rate of 0.5 V/μs, an open loop gain of 90dB with 3MHz Gain Bandwidth Product (GBP) and phase margin of 77°, and a common mode rejection ratio (CMRR) of 62dB.
Abdul Ahad Abro, Erdal Taşci, Aybars Ugur
Balkan Journal of Electrical and Computer Engineering, Volume 8, pp 181-185; doi:10.17694/bajece.679662

Abstract:
Outlier detection is considered as one of the most efficient and crucial research areas for data mining. Many methods have been studied widely and utilized for achieving better results in outlier detection from existing literature; however, the effects of these methods are inadequate. In this paper, a stacking-based ensemble classifier has been proposed along with four base learners (namely, Rotation Forest, Random Forest, Bagging, and Boosting) and a meta-learner (namely, Logistic Regression) to progress the outlier detection performance. The proposed mechanism is evaluated on five datasets from the ODDS library by adopting five performance criteria. The experimental outcomes demonstrate that the proposed method outperforms than the conventional ensemble approaches concerning the accuracy, AUC (Area Under Curve), precision, recall, and F-measure values. This approach can also provide a feasible solution to machine learning problems.
Atilla Dönük
Balkan Journal of Electrical and Computer Engineering pp 164-169; doi:10.17694/bajece.646625

Abstract:
Leakage inductance component has a significant importance in total inductance value of GISR. Neglecting this component in the design phase, results in an expensive and bulky core structure. Variation of leakage inductance component in percentage is determined and presented as graphical curves for M4 steel by applying energy method. FEA are performed for various GISR with several operating voltages and temperature rise values to determine the leakage inductance component. A design tool with Matlab/Guide is also developed for analytical calculations to obtain the physical dimensions for FEA. Graphical curves introduced to the literature in this work provide manufacturers or design engineers to perform fast, reliable and economical GISR design with an alternative material and offer variety.
Meric Cetin, Yunus Sarica
Balkan Journal of Electrical and Computer Engineering pp 147-153; doi:10.17694/bajece.642973

Abstract:
The game development process is becoming a more detailed structure every day. The applications of artificial intelligence (AI), which is a comprehensive information technology, have been closely related to game technologies. In this study, the levelling process of a 2-dimensional (2D) platform game was investigated. The game developed and called “ Renga ” has a basic gameplay. Game data has been processed through an artificial neural network (ANN), k -nearest neighbour, decision and random tree algorithms and deep learning model that is trained with gameplay and user information. The classification process with the output data provides results for the next game level. In this way, the most effective playability impression that the developers offer to the game users has been created according to game. Furthermore, the variety of difficulty calculated with dynamic data by the user is provided by Renga , in which new sections/levels are created with user-specific assets. Thus, the most efficient gaming experience has been transferred to the users.
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