Yazar "Koseoglu, Murat" seçeneğine göre listele
Listeleniyor 1 - 14 / 14
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe An approach for unipolar corona discharge in N2/O2 gas mixture by considering townsend conditions(Elsevier Science Bv, 2011) Alisoy, Hafiz Z.; Yesil, Ali; Koseoglu, Murat; Unal, IbrahimIn this study (alpha/p)=f(E/p) functional relation is derived for the gas mixture of N-2/O-2 by considering Townsend approach, and formation mechanism of corona discharge is investigated for the coaxial electrode system located in this gas medium. The electron energy distribution function (EEDF) which is required for estimation of ionization coefficient, is determined by considering probability distribution function of inelastic electron collisions versus energy. An algorithm for determining ionization coefficient for binary gas mixture is presented. The development and motion of the electron avalanche in inter-electrode gap are studied by considering the effect of positive space charges. It is determined by considering the derived mathematical expressions that the formation of corona discharge is related with the variation of the current characteristics in inter-electrode gaps depending on the change of potential of central electrode. (C) 2011 Elsevier B.V. All rights reserved.Öğe Behavioural modelling of delayed imbalance dynamics in nature: a parametric modelling for simulation of delayed instability dynamics(Taylor & Francis Ltd, 2022) Alagoz, Baris Baykant; Deniz, Furkan Nur; Koseoglu, MuratImbalance dynamics can develop very slowly, and real systems and structures may seem to be stable or balanced for long periods of time before signs of instability behaviour become apparent. This study presents two dynamic system modelling approaches for simulation of delayed instability: Firstly, frequency domain properties of the system instability are investigated, and a parametric model to represent delayed instability behaviour is formulated according to the system pole placement technique. Secondly, a new type of instability modelling approach, which is based on time-domain characteristics of fractional order derivative operators, is introduced by utilizing the finite convergence regions of the Binomial series. This special instability modelling technique essentially uses the region of convergence in the series expansion of impulse responses. Several illustrative modelling and simulation examples are illustrated for engineering problems such as slowly developing cracks in metals, the voltage collapse in power systems and the delayed instability in control systems.Öğe The Changes in Electrical and Interfacial Properties of Polyimide Exposed to Dielectric Barrier Discharge in SF6 Medium(Hindawi Publishing Corp, 2013) Alisoy, Hafiz Z.; Koseoglu, MuratThe formation mechanism of space charges in polyimide (PI) which was exposed to dielectric barrier discharge (DBD) in SF6 medium and the effects of the space charges on interfacial and electrical properties of PI were investigated. The variation of normalized surface charge density on PI sample was calculated and illustrated for different DBD exposure times. The surface potential was measured to determine the effect of the space charges on the sample. Then, the contact angle values were measured to obtain the relation between the surface energy and the surface charge density. The expressions for the total charge and the concentration of trapped electrons were derived by using Poisson and continuity equations at stationary state. The space charges were determined experimentally by using thermally stimulated depolarization current (TSDC) method. Also, SEM image and FTIR spectrum of virgin and treated samples were presented to observe the structural variations. It was seen that the approach for the formation mechanism of the space charges agreed with the experimental data. However, it was concluded particularly for the short-time DBD treatments that the space charges accumulated in the sample should be considered besides the effects of surface functionalization in the determination of the surface energy.Öğe Classification of Hand-Drawn Basic Circuit Components Using Convolutional Neural Networks(Ieee, 2020) Gunay, Mihriban; Koseoglu, Murat; Yildirim, OzalIn this paper, the Convolutional Neural Network (CNN) architecture, which is one of the deep learning architectures, is used to classify the basic circuit components drawn by hand. During the training and testing stages of the model, a new dataset containing images of 863 circuit components manually drawn by different people is created. The data set contains images of four different classes of circuit components such as resistor, inductor, capacitor and voltage source. All images have been fixed to the same size and converted to grayscale to increase recognition performance and reduce process complexity. In the study, training for four classes is performed with CNN architecture. Based on the CNN architecture, four new CNN models are employed with different the number of layers. The training and validation results of these models are compared separately, the model with the highest training and validation performance is observed with four layer CNN model (CNN-4). This model obtained 84.41% accuracy rate at classification task.Öğe Design of a smart glove for monitoring finger injury rehabilitation process via MQTT server(Ieee, 2018) Koseoglu, Murat; Celik, Orkan Murat; Pektas, OmerIn this paper, a wearable glove, which measures hand parameters such as finger angle and force experienced by the finger, was designed by considering four fingers. The hand parameters were measured by using flexible resistive sensors and resistive force sensors. The obtained data were published to Message Queuing Telemetry Transport (MQTT) server via Esp8266 Wi-Fi module. MQTT is a machine to machine (M2M)/Internet of Things connectivity protocol. Then an interface for the application was designed on Visual Studio and the meaningful data were presented to the user and physician. This application receives the data from Mosquitto broker service that uses MQTT protocol, thus the changes in the data can be seen from progress bars on the application form readily, and the rehabilitation process can be monitored by the physician remotely.Öğe Design of an Autonomous Mobile Robot Based on ROS(Ieee, 2017) Koseoglu, Murat; Celik, Orkan Murat; Pektas, OmerIn this paper, design of an autonomous mobile robot (AMR) adapted for robot operating system (ROS) is presented by considering both the hardware architecture and electronic communication protocols. Initially the purpose of the robot has been determined, and then the required components to construct the robot have been obtained. After mounting the electronic and mechanic hardware components on the platform, the required interconnections, data exchange system and software have been installed. Then the required tests have been run on the platform and some solutions methods have been proposed for the problems encountered during the tests. The results obtained and experience gained in the design of the platform have been quite satisfactory and will be a guiding light for future works.Öğe The Effect of Different Noise Levels on The Performance of The Audio Search Algorithm(Ieee, 2020) Koseoglu, Murat; Uyanik, HakanAudio fingerprint technique is a method that creates a unique and compact identity for audio data and is also used to distinguish these identities from each other. In this study, an algorithm, based on the methods used in Shazam 's audio fingerprint technique and hash functions, was developed to recognize multimedia audio files by using MATLAB software, and it was tested against noise factor of different levels. Experimental results have shown that the developed algorithm gives successful results against the noise factor. In addition, it has been understood that the preferred hash function technique has revealed satisfying results in comparison with the conventional techniques.Öğe Effect of Plasma Deposited Thin Carbon Layer on Dielectric Characteristics of Au-PI-Au Structures(Ieee-Inst Electrical Electronics Engineers Inc, 2012) Koseoglu, Murat; Alisoy, Hafiz Z.In this study, dielectric properties of a virgin polyimide (PI) sample and tailored PI sample are investigated in a metal-insulator-metal (MIM) structure comparatively. In order to modify the dielectric properties of the tailored sample, plasma enhanced chemical vapor deposition (PECVD) method was used, and a thin a-C:H layer was deposited on the sample surface. Then dielectric permittivity, dielectric loss and ac conductivity characteristics, which were calculated according to the measured capacitance, loss factor and conductance values, were plotted versus frequency (0.1-100 kHz) and temperature (20-300 degrees C). Also, SEM images and FTIR spectrum of the samples were presented and evaluated. Consequently, a-C:H layer and accompanying plasma polymer interactions during PECVD led to decrease the permittivity of the sample, and increase the thermal stability of the tailored sample relatively.Öğe Effect of Spectrogram Parameters and Noise Types on The Performance of Spectro-temporal Peaks Based Audio Search Method(Gazi Univ, 2023) Koseoglu, Murat; Uyanik, HakanAudio search algorithms are used to detect the queried file in large databases, especially in multimedia applications. These algorithms are expected to perform the detection in a reliable and robust way within the shortest time. In this study, based on spectral peaks method, an audio fingerprint algorithm with a few minor modifications was developed to detect the matching audio file in target database. This method has two stages as the audio fingerprint extraction and matching. In the first stage, fingerprint features are extracted from spectral peaks on the spectrograms of audio files by hash functions. This state-of-art technique reduces the processing load and time considerably compared to traditional methods. In the second stage, fingerprint data of the queried file are compared with the data created in the first stage in the database. The algorithm was demonstrated, and the effect of spectrogram parameters (window size, overlap, number of FFT) was investigated by considering reliability and robustness under different noise sources. Also, it was aimed to contribute to new audio retrieval studies based on spectral peaks method. It was observed that the variation in the spectrogram parameters significantly affected the number of matchings, reliability and robustness. Under high noise conditions, the optimal spectrogram parameters were determined as 512 (window size), 50% (overlap), 512 (number of FFT). It was seen in general that the algorithm successfully detected the queried file in the database even in high noise conditions for these parameters. No significant effect of music genre was observed.Öğe An effective analog circuit design of approximate fractional-order derivative models of M-SBL fitting method(Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Koseoglu, Murat; Deniz, Furkan Nur; Alagoz, Baris Baykant; Alisoy, HafizThere is a growing interest in fractional calculus and Fractional Order (FO) system modeling in many fields of science and engineering. Utilization of FO models in real-world applications requires practical realization of FO elements. This study performs an analog circuit realization of approximate FO derivative models based on Modified Stability Boundary Locus (M-SBL) fitting method. This study demonstrates a low-cost and accurate analog circuit implementation of M-SBL fitting based approximate model of FO derivative elements for industrial electronics. For this purpose, a 4th order approximate derivative transfer function model of the M-SBL method is decomposed into the sum of first order low-pass filters form by using Partial Fraction Expansion (PFE) method, and the analog circuit design of the approximate FO derivative model is performed. Firstly, by using the final value theorem, authors theoretically show that the time response of the sum of first order low-pass filter form can converge to the time response of fractional order derivative operators. Then, the approximation performance of proposed FO derivative circuit design is validated for various input waveforms such as sinusoidal, square and sawtooth waveforms via Multisim simulations. Results indicate an accurate realization of the FO derivative in time response (an RMSE of 0.0241). The derivative circuit realization of the M-SBL fitting model in the form of the sum of first order low pass filters can yield a better time response approximation performance compared to the Continued Fraction Expansion (CFE) based ladder network realization of the approximate derivative circuit.Öğe An efficient PID-based optimizer loop and its application in De Jong's functions minimization and quadratic regression problems(Elsevier, 2022) Alagoz, Baris Baykant; Deniz, Furkan Nur; Koseoglu, MuratThe Proportional-Integral-Derivative (PID) control law has been commonly used for process control in control engineering applications. However, it has potential to work as a solver in optimization problems. This study introduces a PID-based optimizer loop that is designed to solve nonlinear, unconstrained, multi-parameter optimization problems. To achieve the minimization of multi-parameter positive real objective functions by using a closed loop PID control loop, a slope sentient objective function model is suggested to allow zero-crossing of the error signal. Thus, this objective function model enhances the convergence efficiency of the PID-based optimizer loop by indicating slope direction of the objective function and operating in both positive and negative error regions. The boundedness and convergence theorems for the proposed PID optimizer loop are presented, and a theoretical background for the PID-based minimization is established. To demonstrate practical minimization performance, numerical applications of the proposed PID optimizer loops are illustrated in the solution of two fundamental optimization problems. These are the minimization of 30 parameters De Jong's functions and the solution of quadratic regression problems. Also, an experimental study is presented for the quadratic regression modeling of measurement data from a hole-drilling experiment. Optimization results reveal that the proposed PID-based optimizer system can improve convergence speed and accuracy compared to performances of fundamental nonlinear optimization techniques. (c) 2021 Elsevier B.V. All rights reserved.Öğe An experimental analog circuit realization of Matsuda's approximate fractional-order integral operators for industrial electronics(Iop Publishing Ltd, 2021) Koseoglu, Murat; Deniz, Furkan Nur; Alagoz, Baris Baykant; Yuce, Ali; Tan, NusretAnalog circuit realization of fractional order (FO) elements is a significant step for the industrialization of FO control systems because of enabling a low-cost, electric circuit realization by means of standard industrial electronics components. This study demonstrates an effective operational amplifier-based analog circuit realization of approximate FO integral elements for industrial electronics. To this end, approximate transfer function models of FO integral elements, which are calculated by using Matsuda's approximation method, are decomposed into the sum of low-pass filter forms according to the partial fraction expansion. Each partial fraction term is implemented by using low-pass filters and amplifier circuits, and these circuits are combined with a summing amplifier to compose the approximate FO integral circuits. Widely used low-cost industrial electronics components, which are LF347N opamps, resistor and capacitor components, are used to achieve a discrete, easy-to-build analog realization of the approximate FO integral elements. The performance of designed circuit is compared with performance of Krishna's FO circuit design and performance improvements are shown. The study presents design, performance validation and experimental verification of this straightforward approximate FO integral realization method.Öğe Revisiting four approximation methods for fractional order transfer function implementations: Stability preservation, time and frequency response matching analyses(Pergamon-Elsevier Science Ltd, 2020) Deniz, Furkan Nur; Alagoz, Baris Baykant; Tan, Nusret; Koseoglu, MuratDue to high computational load of ideal realization of fractional order elements, fractional order transfer functions are commonly implemented via integer-order, limited-band approximate models. An important side effect of such a non-ideal fractional order controller function realization for control applications is that the approximate fractional order models may deteriorate practical performance of optimal control tuning methods. Two major concerns come out for approximate realization in fractional-order control. These are stability preservation and model response matching properties. This study revisits four fundamental fractional order approximation methods, which are Oustaloup's method, CFE method, Matsuda's method and SBL fitting method, and considers stability preservation, time and frequency response matching performances. The study firstly presents a detailed review of Oustaloup's method, CFE method, Matsuda's method. Then, a modified version of SBL fitting method is presented. The stability preservation properties of approximation methods are investigated according to critical root placements of corresponding approximation method. Stability issue is highly significant for control applications. For this reason, a detailed analysis and comparision of stability preservation properties of these four approximation methods are investigated. Moreover, approximate implementations of an optimally tuned FOPID controller function are performed according to these four methods and compared for closed loop control of a large time delay system. Findings of this study indicate a fact that approximate models can considerably influence practical performance of optimally tuned FOPID control systems and ignorance of limitations of approximation methods in optimal tuning solutions can significantly affect real world performances. (C) 2020 Elsevier Ltd. All rights reserved.Öğe Time response optimal rational approximation: Improvement of time responses of MSBL based approximate fractional order derivative operators by using gradient descent optimization(Elsevier - Division Reed Elsevier India Pvt Ltd, 2022) Koseoglu, MuratFractional calculus has become a popular topic in recent years. Its applications have been seen frequently in the analysis and solution of many engineering problems. Since, the exact realization of fractional order (FO) operators is not computationally feasible, several integer order approximations methods such as Oustaloup, Matsuda, Curve Fitting, modified stability boundary locus (MSBL) are utilized for frequency domain approximation of FO operators. These methods present advantages in frequency response approximation. However, real-world engineering applications require more accurate time responses to implement FO operators. Thus, any improvement in the approximate transfer function of FO systems will positively contribute to realization performance of FO system models in real-world applications. In this work, time responses of MSBL based approximate FO derivative models are improved by using gradient descent optimization (GDO) technique. Frequency domain approximation methods do not guarantee optimal approximation performance for the step response of FO elements. To deal with this weakness, author proposes a new GDO based rational approximation scheme that can considerably enhance the step response performance of MSBL method without deteriorating frequency response approximation performance. Results for the improved approximate FO model obtained by GDO (GDO-MSBL) are compared with the results of approximate FO models for popular FO approximation methods. The analog circuit realization is performed for the derivative operator, and the performance improvements for the proposed method are shown on the FO-PID controller and FO filter. (C) 2022 Karabuk University. Publishing services by Elsevier B.V.
