Elektrik-Elektronik Mühendisliği Bölümü / Department of Electrical and Electronics Engineering
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Publication 3-Phase Induction Motor Drive with PWM Modulator Using a 8-Bit Low Cost Micrcontroller(2004) Küçükgüzel, E.; Bilgiç, Mehmet Oruç; 1616This paper describes a study on a well studied subject, driving 3-phase induction motor. But the hardware used for the study is different than the conventional 16-bit microcontrollers or DSPs. The aim of the project is to lower the price of control hardware and achieve a satisfying performance with less expensive 8-bit microcontrollers.Publication A CNN based rotation invariant fingerprint recognition system(Istanbul Unıv, Fac Engineering, Elektrik-Elektronik Mühendisliği Bölümü, Avcılar Kampüsü, İstanbul, 34320, Turkey, 2017) Çelik Mayadağlı, Tuba; Saatçı, Ertuğrul; Rifat, Edizkan; 10488; 16117; 16117This paper presents a Cellular Neural Networks (CNN) based rotation invariant fingerprint recognition system by keeping the hardware implementability in mind. Core point was used as a reference point and detection of the core point was implemented in the CNN framework. Proposed system consists of four stages: preprocessing, feature extraction, false feature elimination and matching. Preprocessing enhances the input fingerprint image. Feature extraction creates rotation invariant features by using core point as a reference point. False feature elimination increases the system performance by removing the false minutiae points. Matching stage compares extracted features and creates a matching score. Recognition performance of the proposed system has been tested by using high resolution PolyU HRF DBII database. The results are very encouraging for implementing a CNN based fully automatic rotation invariant fingerprint recognition system.Publication A New Method for Doppler Centroid Estimation Based on Block Processing(IEEE, 345 E 47Th St, New York, Ny 10017 Usa, 2013) Kartal, Mesut; Tunçay, Pelin; 43246; 187162Doppler centroid frequency is an important parameter for Synthetic Aperture Radar signal processing, which is used to design a proper matched filter in azimuth domain. Doppler centroid is estimated from the received data. There are number of different algorithms for the Doppler centroid estimation presented in the literature. In all these algorithms, a general the Doppler centroid estimation is done for the whole data. Thus, some distortions occur in the final image away from the scene center for where the Doppler centroid is estimated. To overcome this problem, an alternative method for the Doppler centroid estimation, which is based on block processing, is presented. This method also takes advantage for saving time when the interested area is small.Publication A novel EOG-based wireless rapid communication device for people with motor neuron diseases(Taylor and Francis Online, 2018-11-22) Uşaklı, Ali Bülent; Gürkan, Serkan; GÜRKAN, GÜRAY; 118889; 244333; 113297In this study, a new electrooculography (EOG) based system that provides efficient communication for people suffered from motor neuron diseases is presented. The system consists of two distinct devices. The first device operates as a main unit that is activated by the subject’s eye movements. This unit is capable of transmitting 10 different command/state messages. These messages enable subject to choose his/her situation such as “I’m fine”, “I feel bad”, “I’m hungry” and “I’m thirsty”. Commands such as “Come”, “Go”. The number of messages can be increased. The main unit acquires the EOG signal from the subject. Newly developed analogue and digital signal conditioning interprets the eye movements as specific messages and transmits them to the second unit (receiver) using radio frequency transmitter. The messages related to the subject’s demands and situation can be heard from both main and receiver unit speakers. The wireless receiver unit is capable of notifying the patient’s command by auditory and visual indicators. The realised device was tested by 2 healthy and 2 ALS patients and confirmed to be successful with 100% performance for sending correct messages.Publication Accreditation for cademic quality(Int Scientific Conference SGEM, 14, Kilment Ohridsky BLVD, Sofia, 1797, Bulgaria, 2008) Şenel, Seçil; Yalçın, Dilek; 104470; 114377As it is well-known, the latest trend in academia has been the rapid growth of online or distance learning courses. Globalization makes mobility easy and possible. That is why a graduate has the opportunity to find not only a nationwide but also a worldwide occupation. In most countries in the world, the function of accreditation for educational institutions is conducted by a government ministry of education. The purpose of this study is presenting the goal of the accreditation. The goal of accreditation is to ensure that education provided by institutions of higher education meets acceptable levels of quality. In order to present the educational philosophy that monitors the international values and standards, ABET (Accreditation Board for Engineering and Technology) in engineering education and international standards in medical education are taken into consideration. Engineering departments of a few universities have been accredited with respect to the ABET criteria. In medical education a few universities have been initiating the accreditation process in Turkey. In this study, the accreditation and assessment methods in higher education are discussed.Publication Adaptive dual-mode OFDM with index modulation(Elsevier Science Bv, Po Box 211, 1000 Ae Amsterdam, Netherlands, 2018-10) Aldırmaz Çolak, Sultan; Başar, Ertuğrul; ACAR, YUSUF; 41633; 237377; 149116With the integration of the index modulation concept, the popular OFDM has gained an appealing new dimension. However, OFDM with index modulation (OFDM-IM) causes a decrease in data rate for higher order modulations due to its unused subcarriers. Recently, dual-mode OFDM with index modulation (DM-OFDM-IM) has been proposed to prevent this decrease in data rate. The spectral efficiency (SE) of both techniques depends on the selection of different parameters, such as modulation types and number of active subcarriers. However, the quality of the wireless channel has not been taken into account yet to increase the data rate. In this paper, we propose a new adaptive DM-OFDM-IM (A-DM-OFDM-IM) system to enhance the bit error probability (BER) performance considering the channel conditions and obtain a substantial increase in SE. Unlike the previous DM-OFDM-IM and the classical OFDM-IM schemes, our proposed system enables the use of different types of modulations for different subblocks in one OFDM signal. We demonstrate that the SE of the proposed system is comparable with that of its OFDM-IM and DM-OFDM-IM counterpart under frequency selective Rayleigh channels. Moreover, computer simulations corroborate that the derived theoretical results are considerably accurate for the SE of A-DM-OFDM-IM systems. (C) 2018 Elsevier B.V. All rights reserved.Publication Adjective Check List and Psychological Stress: Evidence From Turkey(Int Scientific Conference SGEM, 14, Kilment Ohridsky BLVD, Sofia, 1797, Bulgaria, 2008) Erkoç, Tuba; Kurt, Doğuş; Bayramoğlu, Oya; Yıldırım, Halil; Yıldırım, OsmanIt is called stress when an individual begins to act different physically and mentally as a result of the fact that he or she is affected by the environment lie or she lived and worked in. To block or balance the process of adaptation to stressful circumstances of people can be in different ways. However, it may not be possible to get rid of stress completely. So that, an individual who is overstressed can suffer aggressiveness, non-confidence, difficulties in focusing, chronic tiredness, tension, sadness, anxiety, anger, poor health, depression, etc. Naturally, this causes the individual, who is overstressed, to have mental, physical, and psychological illnesses. As a result, it becomes more difficult for the individual to adapt his or her social environment. In this research, the stress levels of the parents having disabled students was assessed using Abidin's (1990) Parenting Stress Index (PSI) on a sample of 190 parents. According to the results, it has been achieved that parents who has low socio-economic status, are exposed to more stress to the extent of parenting distress.Publication Aircraft sensor fault detection based on unknown input observers(Emerald Group Publishing Limited, Howard House, Wagon Lane, Bingley Bd16 1Wa, W Yorkshire, England, 2008) Çetin, Ömer; Kıyak, Emre; Kahvecioğlu, Ayşe; 288107; 19395; 199397Purpose - The purpose of this paper is to generate residuals which can be used to detect fault and isolate on a vertical takeoff and landing (VIOL) aircraft dynamic model. Design/methodology/approach - In the proposed approach, a generalized observer scheme method based on an unknown input observer is used for residual generation and applied to detect and isolate a faulty sensor. A bank of robust unknown input observers estimates the state variables of the system and gathers necessary information for fault detection and isolation purposes. Findings - A sinus signal is considered as a non-linear disturbance in simulations. A failure simulation was prepared in different times. In this situation an unknown input observer should be designed which could predict the states of the system against the disturbances or unknown inputs. In the real world, there exist unknown inputs such as system non-linearities, noise and disturbances. The paper shows that the system based on UIO is robust for unknown inputs mentioned above. Originality/value - It is simulated on a VTOL dynamic model using MATLAB/Simulink. Any single sensor fault could be detected and isolated correctly. This kind of observer is also robust and flexible.Publication Akciğer Basınçlarının İnvasiv Olmayan Yöntemler ile Kestirilmesi Amacıyla Akciğer Basınçları Ve Akciğer Sesleri Arasındaki İlişkinin Modellenmesi(TÜBİTAK EEEAG Proje, 2020) SAATÇI, ESRA; Öztürk, Ayşe Bilge; SAATÇI, ERTUĞRUL; Akan, aydınSolunum fonksiyon testleri solunum hastalıklarının teshis ve tedavisinin izlenmesinde kullanılırlar. Hastane ortamında yapılan bu testler pahalı cihazlara ve hastalar tarafından yapılan çesitli solunum manevralarına ihtiyaç duyarlar. Bu projenin amacı klinikte kullanılan solunum fonksiyon testlerinin yerine basit yöntemler ile solunum parametrelerinin bulunmasıdır. Bu amacı gerçeklestirmek için akciger basınçlarının girisimsel olmayan yöntemler ile kestirilmesi gerekmektedir. Basit mikrofonlar ile ölçülen akciger seslerinin ve havayolu gaz akıs hızı, sıcaklıgı ve nemi gibi çesitli solunum sinyallerinin istatistiksel ve fraktal sinyal isleme yöntemleri ile islenmesi bu projede önerilen temel yöntemdir. Solunum parametrelerinin kestiriminde bazı sinyal isleme yaklasımları önerilmis olsa bile solunum sesleriyle beraber istatistiksel ve fraktal sinyal isleme yöntemleri kombinasyonunun kullanılması bu projenin yenilikçi kısmıdır. Yapılan analizler sonucunda derin ve normal solunumların birlikte kullanıldıgı bronsial solunum sesinden elde edilen Hurst üstelinin agız içi basıncının kestiriminde en basarılı sonuçları verdigi görülmüstür. Ayrıca viskoelastik modelin yardımıyla kestirilen akciger basınçlarının gücü en iyi spirometrik testlerde FEV1 ve FVC parametreleriyle IOS testinde R5 parametresi ile ilişkilidir.Publication Amiyotrofik Lateral Skleroz Hastaları için EOG Tabanlı Kablosuz İletişim Cihazının Tasarımı ve Gerçekleştirilmesi(2012) Gürkan, Serkan; 244333Publication Amiyotrofik Lateral Skleroz Hastaları için Göz Kırpma Esaslı Yeni Bir Kolay İletişim Cihazı: EyePad®(2012) Gürkan, Serkan; Uşaklı, Ali Bülent; GÜRKAN, GÜRAY; 244333; 113297; 118889Bu bildiride, istemli göz kırpma hareketi sonucu oluşan elektrookülogram ve elektromiyogram sinyalleri ve özgün olarak tasarlanan sanal klavye (EyePad® ) vasıtası ile kontrol edilebilen ve amiyotrofik lateral skleroz (ALS) motor nöron hastalarının dış dünya ile kolay iletişimini sağlayabilecek bir sistem sunulmaktadır. Göz kırpma sinyalinin sürekli ve rahat bir şekilde alınabilmesi için tasarlanan elektrot yerleştirilmiş gözlük, kullanımı kolaylaştırmıştır. Bu sinyalin varlığı, mobil ünitede bulunan yükselteç, karşılaştırıcı ve radyo frekans verici ile sanal klavyenin bulunduğu bilgisayardaki alıcıya kablosuz olarak gönderilmektedir. Tasarlanan sanal klavye ile 5 harfli bir kelime 15 saniyede yazılabilmektedir.Publication An Arduino UNO application: GPS guided unmanned ground vehicle(IEEE, 345 E 47Th St, New York, Ny 10017 USA, 2017) Bozik, Tugay; GÜRKAN, GÜRAY; 113297This paper presents an application of Arduino UNO to GPS guided unmanned vehicle. The four-wheeled small scale (55 cm x 25 cm) vehicle is capable of moving forward, rotating and consists of a GPS sensor, a magnetometer, a motor driver and four DC motors. The target coordinates (key points) are manually entered as a part of the control algorithm script (.ino file). The developed control algorithm makes a blind calculation of the distance and required rotation between consecutive key points. The initial coordinates of the vehicle, however, requires the only field-dependent calculation of the distance and target heading between the initial and the first key point. The whole target route is achieved by consecutive "rotation" and "forward movements (straight path)" between key points. The GPS sensor is used to determine the initial coordinates whereas magnetometer is used to determine the heading (and rotation) before (and during) each key point movement. When taxiing through blind-calculated route, the acquired GPS data is transmitted via Bluetooth for offline monitoring.Publication An FPGA implementation of 2-D CNN Gabor-type filter(IEEE, 345 E 47TH ST, NEW YORK, NY 10017 USA, 2007) Saatçı, Ertuğrul; Cesur, Evren; Tavşanoğlu, Vedat; Kale, İzzet; TR10488; TR36339A field programmable gate array (FPGA) implementation of the Gabor-type filter is presented. The implementation uses the forward Euler approximation with optimal step size to solve the CNN cell-state equation. The FPGA is implemented on Xilinx Spartan XC3S400 device using 219 slices. An image of dimension 60 x 60 can be processed without using any external RAM only with the block RAM.Publication Analysis of brain connectivity changes after propofol injection by generalized partial directed coherence(Academic Press Inc Elsevier Science, 525 B St, Ste 1900, San Diego, Ca 92101-4495 Usa, 2014) Akan, Aydın; Özkan Seyhan, Tülay; GÜRKAN, GÜRAY; 113297; 2918; 25235In this paper we present a method for the analysis of multichannel EEG by using Generalized Partial Directed Coherence (gPDC) to extract cortical connectivity changes under anesthesia. 15 channel EEG data were recorded from female subjects undergoing general anesthesia for gynecological surgery. Multivariate Autoregressive (MAR) modeling was applied to multichannel, bipolar EEG segments of awake and anesthetized states. gPDCs were calculated using the derived MAR model and averaged through EEG alpha frequency band (8-14 Hz) and through a number of data segments. The gPDC calculation was performed for three different sets of bipolar EEG channel pairs each of which mainly represent a specific scalp area. To derive consistency levels of gPDC values, surrogate analysis is also performed. Using paired t-test for 12 patients, we extracted significant gPDC changes between. awake and anesthetized stages for each set. Analysis revealed that during transition from awake to anesthetized stage, gPDCs of central. to parietal directions were suppressed whereas gPDCs of parietal to central directions were increased. The results indicate that the proposed gPDC analysis method can be used to track the changes in brain connectivity and hence to estimate the depth of anesthesia. (C) 2013 Elsevier Inc. All rights reserved.Publication Analysis of inductor-converter bridge by means of state-space averaging technique (superconducting magnet energy storage)(1988) Bilgiç, Mehmet Oruç; Ehsani, M.; 1616The time-averaged behavior of an inductor-converter bridge (ICB) circuit has been analyzed using a state-space averaging technique. The application of the state-space averaging technique to the ICB circuit analysis is somewhat different from the well known DC-to-DC converter cases such as buck, boost, and flyback of Cuk converter analysis in that the first-order approximation of the state transition matrix will give trivial results. The results, which were previously obtained in infinite Fourier series form, are in closed form. A comparison is also made with the Fourier result. The ICB is a two-quadrant power supply for superconductive energy storage magnets. Closed-form expressions are found for the average current, voltage, and power behavior of the ICB. This application is somewhat different from the analysis of other DC choppers such as buck, boost, flyback, and Cuk converters in that the first-order terms are identically zero and the second-order terms have to be used.Publication Analysis of linear lung models based on state-space models(Elsevier Ireland Ltd., 2020-01) Saatçi, Ertuğrul; Akan, Aydın; SAATÇI, ESRABackground and Objectives: Linear parametric respiratory system models have been used in the model-based analysis of the respiratory system. Although there are studies exploring the physiological correctness and fitting accuracy of the models, they are not analysed in terms of interaction between parameters and dynamics of the model. In this study we propose to use state-space modelling to yield the time-varying nature of the system incorporated by the parameters. Methods: We tested controllability, observability and stability characteristics of the equation of motion, 2-comp. parallel, 2-comp. series, viscoelastic, 6-element and mead models while using the parameters given in the literature. In the sensitivity analysis we proposed to use dual Desensitized Linear Kalman Filter (DKF) and Extended Kalman Filter (EKF) method. In this method, state error covariance revealed the parameter sensitivities for each model. Results: Results showed that all models, except 2-comp. parallel and mead models, are both controllable and observable models. On the other hand all models, except mead model, are stable models. Regarding to the sensitivity analysis, dual DKF - EKF method estimated states of the models successfully with a low estimation error. Sensitivity analysis results showed that airway parameters have higher effects on the state estimation than the other parameters have. Conclusion: We proved that state-space evaluation of the previously proposed parametric models of the respiratory system led us to quantitative and qualitative assessments of the respiratory models. Moreover parameter values found in the literature have different effects on the models. (C) 2019 Elsevier B.V. All rights reserved.Publication Analysis of Single Flying Capacitor Converter by the State-Space Averaging Technique(IEEE, 1988) Bilgiç, Mehmet Oruç; Ehsani, M.; 1616The single flying capacitor converter (SFCC) is a two-quadrant power supply for energy storage and transfer system. It has applications in nuclear research and pulsed power systems in which superconductive coils are used in superconductive magnets. The authors derive analytical expressions for the time-averaged behavior of the SFCC by using the state-space averaging technique. Useful expressions are found for the average behavior of the SFCC. The results can be used in the design, control, and optimum operation of the system.Publication Application of Stockwell Coherence To Prediction Of Alertness Under Anaesthesia(Brno Univ Technology Vut Press, Purkynova 118, Brno 61200, Czech Republic, 2010) Akan, Aydın; Demiralp, Tamer; GÜRKAN, GÜRAY; TR113297; TR2918; TR6916In this paper, we represent an application of Stockwell Coherence to scalp EEG signals under anesthesia. By the analysis of overlapping, stationary data segments, we obtained the time-varying Stockwell coherence, which reveals the time evolution of coherence changes between any selected channel pair. After the injection and release of the anesthetic agent, time-varying Stockwell coherence analyses demonstrate similar characteristics for different patients.Publication Application of stockwell coherence to prediction of alertness under anaesthesia(2010) Akan, Aydın; Demiralp, Tamer; GÜRKAN, GÜRAY; 113297; 2918In this paper, we represent an application of Stockwell Coherence to scalp EEG signals under anesthesia. By the analysis of overlapping, stationary data segments, we obtained the time-varying Stockwell coherence, which reveals the time evolution of coherence changes between any selected channel pair. After the injection and release of the anesthetic agent, time-varying Stockwell coherence analyses demonstrate similar characteristics for different patients.Publication Bandpass sampling of multiband signals by using geometric approach(IEEE, 345 E 47th St, New York, Ny 10017 USA, 2017) Saatçı, Ertuğrul; Akan, Aydın; SAATÇI, ESRA; 112197; 10488; 2918This paper presents a simple and fast approach to f nd a minimum sampling frequency for multi-band signals. Instead of neighbor and boundary conditions, constraints on the sampling frequency were derived by using the geometric approach. Reformulation of the minimum sampling determination problem by using geometric approach enables to represent the problem as a basic inequality problem. Recursive algorithm was proposed to solve the constraints on the minimum sampling frequency. The proposed method was verif ed through numerical simulations in terms of the minimum sampling frequency and the computational eff ciency by using 2-band and 3-band signals. Although the results illustrated the valid minimum sampling frequencies for the multi-band signals, due to the increase in the number of iterations, optimization approaches were recommended in the solution of the constraints on the minimum sampling frequency.