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Öğe Control of the Bed Temperature of a Circulating Fluidized Bed Boiler by using Particle Swarm Optimization(Univ Suceava, Fac Electrical Eng, 2012) Aygun, Hilmi; Demirel, Huseyin; Cernat, MihaiCirculating fluidized bed boilers are increasingly used in the power generation due to their higher combustion efficiency and lower pollutant emissions. Such boilers require an effective control of the bed temperature, because it influences the boiler combustion efficiency and the rate of harmful emissions. A Particle-Swarm-Optimization-Proportional-Integrative-Derivative (PSO-PID) controller for the bed temperature of a circulating fluidized bed boiler is presented. In order to prove the capability of the proposed controller, its performances are compared at different boiler loads with those of a Fuzzy Logic (FL) controller. The simulation results demonstrate some advantages of the proposed controller.Öğe Moving object detection using an adaptive background subtraction method based on block-based structure in dynamic scene(Elsevier Gmbh, 2018) Savas, M. Fatih; Demirel, Huseyin; Erkal, BilgehanToday, determining background which forms the basis of the video surveillance system whose use is increasing in parallel with developing technology, is a complicated process to implement for cases involving dynamic scene. In this study, we proposed a block-based adaptive method which can be adaptable to dynamic environmental conditions. By grouping the pixels in the picture frame as 2 x 2 non-overlapped blocks, we reduced the amount of noise and the time delay caused by processing of pixels. By a simple counter structure, we created an adaptive threshold parameter which can be adapted according to the case in N surrounding. We used this parameter to perform an update of the background model and reduced background model normalization process. So, we reduced the update time of background operably. Our proposed method achieved successful results in levels of grey levels. (C) 2018 Elsevier GmbH. All rights reserved.Öğe Multi-Criterion Design and 2D Cosimulation Model of 4 kW PM Synchronous Generator For Standalone Run-of-the-River Stations(Ieee, 2015) Cetinceviz, Yucel; Uygun, Durmus; Demirel, HuseyinThis study reports the analytical computation including performance characteristics such like load line voltage and output power in combination with coupled-field circuit analysis of a 4kW direct drive permanent magnet synchronous generator (PMSG) to be used in a micro-scale run-of-the-river-station application. The specifications such like slot opening, pole embrace and magnet length of PMSG are optimized by using parametric approach including multi-criterion design optimization. Based on the optimized design, the model has been exposed to some transient coupled-field circuit analyses based on variable river flow speed and variable ohmic load conditions. The analytical studies related to finite element methods and conducted parametric approaches verified the effectiveness of the employed dynamic co-simulations.Öğe Noise Reduction using MRF and Block-Based Background Modeling in Dynamic Scenes Input(Int Journal Computer Science & Network Security-Ijcsns, 2017) Savas, M. Fatih; Demirel, HuseyinIdentifying the moving foreground object in dynamic scenes and making the analysis of video sequences accurate and powerful is an important process for video surveillance systems. Environmental factors such as environmental noises and sudden light changes are the main factors of the degradation of the background model. Complex algorithms are needed to create a strong background against these factors. In this study, We increased the noise immunity of the background model exposed to environmental noise by applying Markov random field (MRF) to block-based modified KDE (Kernel Density Estimation). We also reduced the storage space requirement with the KDE structure we created in blocks. Thus we have increased the applicability of this structure to a real-time structure.Öğe A Novel MPPT Method for PV Arrays Based on Modified Bat Algorithm with Partial Shading Capability(Int Journal Computer Science & Network Security-Ijcsns, 2017) Karagoz, M. Kadir; Demirel, HuseyinThe power-voltage curve of photovoltaic arrays has one global peak and one or more local peak under partially shaded conditions. The conventional maximum power point tracking algorithms such as Perturb&Observe are converge to the first peak. Therefore they may not find global maximum power point. However; soft computing methods such as Bat Algorithm may find it. This paper proposes a dual algorithm search method that consist of modified Bat Algorithm and Perturb&Observe algorithm. The standard Bat Algorithm has been modified by adding a similar feature to tabu list of Tabu Search Algorithm. In search process, firstly, modified Bat Algorithm is used to determine the area of global peak, then Perturb&Observe is replaced to track the maximum power point in the area of global peak. If the power varies greatly and rapidly, the search process starts again. Standard Bat Algorithm, Perturb&Observe and the proposed method are simulated under standard test condition and partially shaded conditions. The simulations show that performans of the proposed method is superior to both the standard Bat Algorithm and Perturb&Observe.Öğe Optimal Design and Verification of a PM Synchronous Generator For Wind Turbines(Int Journal Renewable Energy Research, 2017) Cetinceviz, Yucel; Uygun, Durmus; Demirel, HuseyinThis study reports the analytical computation including performance characteristics under no-load condition in combination with coupled 2D electromagnetic field-circuit analysis of a 4kW direct drive permanent magnet synchronous generator (PMSG) to be used in micro-scale wind turbine applications. The specifications such like stack length, skew and magnet offset of PMSG are optimized by using parametric approach including multi-objective design optimization. It describes the methodology to gain required output performance such as output power, load voltage and maximum efficiency of the wind generator. Based on the optimized design, the model has been exposed to some transient coupled-field circuit analyses based on variable wind flow speed under no-load conditions. In addition to these evaluations; the experimental results verified the effectiveness of the employed simulations model related to finite element methods and analytical studies showing that that the induced voltage at nominal speed and no-load condition is at desired level and results obtained under no-load condition are in good agreement with the analysis and analytical results.Öğe Performance and cooling efficiency of thermoelectric modules on server central processing unit and Northbridge(Pergamon-Elsevier Science Ltd, 2015) Tan, Serhat Orkun; Demirel, HuseyinComputer systems are required to process data more rapidly than ever, due to recent software and internet technology developments. The server computers work continuously and provide services to many clients simultaneously, which results in greater heat production and high temperature that must be managed in order to avoid malfunction and failure of critical hardware. In this study, three cooling systems were used, comparatively to examine the temperature and performance of the CPU and motherboard. The temperature characteristics and performance of the CPU were tested with a heat sink, water cooling system, and thermoelectric cooler. According to the test results, the thermoelectric cooling system has better cooling performance than the other two systems under continuous operating conditions. Additionally, the performance rating of the CPU was the best with a thermoelectric cooler under varying workloads. (C) 2015 Elsevier Ltd. All rights reserved.Öğe Performance evaluation of a fuzzy variable structure satellite attitude controller under sensor data delay(Tubitak Scientific & Technological Research Council Turkey, 2014) Erkal, Bilgehan; Demirel, HuseyinOne of the main sources of uncertainties in controlling the attitude of a satellite is the time delays seen in sensor data. Although it is possible to process sensor data to correct the deficiencies caused by delays, it is more suitable to design the controller robust enough to handle uncertainties well. In this study, the attitude of a 3-degrees of freedom satellite model, incorporating uncertainties (both sensor data delay and actuator misplacements), is controlled using a suitably designed fuzzy variable structure controller (FVSC). The performance of the FVSC is evaluated and compared to that of other reference controllers [proportional-derivative (PD), linear-quadratic-Gaussian (LQG), and loop-shaping controllers (LSCs)]. The FVSC performs well in both nondelayed and delayed (T-d = 0.2 s and 0.4 s) cases, while the PD and LQG controllers provide good response only for nondelayed cases (i.e. T-d = 0 s). A robust LSC also performs well in both cases, but its root mean squared error is high compared to the FVSC in the delayed case.Öğe Prediction of the brain temperature from other body temperatures in hypothermia induced rats by using artificial neural networks(Pergamon-Elsevier Science Ltd, 2012) Demirel, Huseyin; Goktas, H. Haldun; Erkal, Bilgehan; Ciylan, BunyaminIn this study, a microcontroller based temperature controlled hypothermia induction system is realized. The novelty of the experimental system is in using a thermoelectric Peltier cooler to bring the body temperature to hypothermic levels. The right and left ear, rectum, and brain temperatures of a rat are measured with this system. Then, an artificial neural network (ANN) is trained using temperature data to predict brain temperature from other body temperatures. It is shown that the system has the capability to predict the brain temperature with low error from rectum temperature measurements. The results from this empirical prototype also show that it is possible to use the system on humans to induce local hypothermia safely, where an interior temperature probe in the scalp is eliminated. (C) 2012 Elsevier Ltd. All rights reserved.Öğe Transient analysis with coupled field-circuit model and experimental assessment of a PMSG used in small-scale wind turbine for water heating purpose(Springer, 2019) Cetinceviz, Yucel; Sehirli, Erdal; Uygun, Durmus; Ocak, Cemil; Demirel, HuseyinThis paper introduces the detailed coupled field-circuit analysis including performance characteristics of a 4-kW in-running rotor permanent magnet synchronous generator (PMSG) used in rural-type small-scale wind turbines for water heating purpose. The content of the work consists of design, analysis, optimization, production and testing processes and validation studies. An integrated 2D electromagnetic field and circuit model are used in the design and analysis processes. The electrical machine design involves complex and time-consuming processes. This model provides comprehensive information on machine behavior under different conditions and is an effective to demonstrate compliance with real load conditions prior to the manufacture. The goal of the optimization process is to find a design that offers cost, manufacturability and efficiency as well as generator output values. For this, a multiobjective optimization approach has been used. Typical design and simulation principles are applied to the designed PMSG, respectively, including calculation and evaluation of various output parameters for different simulated wind speed rates and varying load conditions. Furthermore, the analytical studies related to finite element methods and parametric approaches are presented in collaboration with experimental studies carried out for different load rates.Öğe A VHDL application for kinematic equation solutions of multi-degree-of-freedom systems(Zhejiang Univ, 2014) Erkol, Huseyin Oktay; Demirel, HuseyinAs kinematic calculations are complicated, it takes a long time and is difficult to get the desired accurate result with a single processor in real-time motion control of multi-degree-of-freedom (MDOF) systems. Another calculation unit is needed, especially with the increase in the degree of freedom. The main central processing unit (CPU) has additional loads because of numerous motion elements which move independently from each other and their closed-loop controls. The system designed is also complicated because there are many parts and cabling. This paper presents the design and implementation of a hardware that will provide solutions to these problems. It is realized using the Very High Speed Integrated Circuit Hardware Description Language (VHDL) and field-programmable gate array (FPGA). This hardware is designed for a six-legged robot and has been working with servo motors controlled via the serial port. The hardware on FPGA calculates the required joint angles for the feet positions received from the serial port and sends the calculated angels to the servo motors via the serial port. This hardware has a co-processor for the calculation of kinematic equations and can be used together with the equipment that would reduce the electromechanical mess. It is intended to be used as a tool which will accelerate the transition from design to application for robots.
