Scopus İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/395
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Article Citation - WoS: 24Citation - Scopus: 33Variable Structure Controllers for Unstable Processes(Elsevier Sci Ltd, 2015-08) Ablay, GunyazA variable structure control (VSC) method for unstable industrial processes is proposed. The proposed control method is able to provide a highly satisfactory system performance and to tackle with robustness issues of the processes in the presence of uncertainties. An ITAE-based numerical tuning algorithm for acquiring optimal control parameters, and a direct auto-tuning mechanism for the proposed controller are also provided. The performance of the proposed VSC method is illustrated on some unstable process models including a continuous stirred tank reactor (CSTR), in order to show its effectiveness, validity and feasibility. (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 22Citation - Scopus: 24Online Condition Monitoring of Battery Systems With a Nonlinear Estimator(IEEE-Inst Electrical Electronics Engineers Inc, 2014-03) Ablay, GunyazThe performance of batteries as uninterruptable power sources in any industry cannot be taken for granted. The failures in battery systems of safety-related electric systems can lead to performance deterioration, costly replacement, and, more importantly, serious hazards. The possible failures in battery systems are currently determined through periodic maintenance activities. However, it is desirable to be able to detect the underlying degradation and to predict the level of unsatisfactory performance by an online real-time monitoring system to prevent unexpected failures through early fault diagnosis. Such an online fault diagnosis method can also contribute to better maintenance and optimal battery replacement programs. A robust nonlinear estimator-based online condition monitoring method is proposed to determine the state of health of the battery systems online in industry. Real-world experimental data of a modern battery system are used to assess the efficiency of the proposed approach in the existence of parameter uncertainties.Article Citation - WoS: 22Citation - Scopus: 24Novel Chaotic Delay Systems and Electronic Circuit Solutions(Springer, 2015-05-07) Ablay, GunyazChaotic delay systems are abundant in nature and play a significant role in engineering applications and in describing global behaviors of physical systems. This work presents novel first-order chaotic delay systems with the simplest nonlinearities. The exponential, absolute value, and hyperbolic and signum functions, which arise in many systems like electronic circuits, are utilized to generate chaotic delay systems. The practical realization of chaotic delay systems is carried out with all-pass filters and diode-based electronic circuits. Bifurcation diagrams using numerical simulations and experimental results are provided to verify the existence and feasibility of the novel chaotic delay systems. It is expected that the novel chaotic delay systems and the novel electronic implementation circuits will contribute to some practical applications and modeling of physical systems or events in different fields.Article Citation - WoS: 3Citation - Scopus: 3Key Role of High-Tc Twinned Martensitic Materials to Gain a Magnetic Actuation Higher Than 15%(Elsevier Science SA, 2021-12) Sarli, Numan; Paran, Nejdet; Ablay, Gunyaz; Ocak, Hamza Y.; Yildiz, Yasin G.; Yildiz, Gokcen D.; Yagci, Nermin K.Twinning angle outcomes of the twinned martensitic (TM) and detwinned martensitic (DTM) structural transformations on the magnetic features of the austenite (A) parent phase are researched by using the effective field theory established by Kaneyoshi. The implementation of the effective field theory verifies that the shape memory mechanism occurs with phase transformations, A -> TM -> DTM -> A. It also shows that the austenite parent phase has two types of actuations: one-dimensional actuation (in only y-axis) for TM, and two-dimensional actuation (in x and y-axes) for DTM. Magnetic field-induced actuation (strain) in the range of 5-15% at twinning angle theta >= 120.816 degrees of TM and DTM is reported for some materials in the literature. On the other hand, in this work, it is estimated that a twinning angle lower than this twinning angle (i.e., theta < 120.816 degrees) must be achieved to have a strain higher than 15%. We also suggest that materials with higher magnetization, Curie temperature, coercive field and remanence magnetization should be taken into account to get a strain higher than 15%, since all these features are directly affected by the twinning angle (theta). Our results on Curie temperature (T-c) match with the experimental results of Ni49.8Mn28.5Ga21.7 (achieved 6% strain) with T-c = 95 degrees C (368 K) by Murray et al., and Ni46Mn24Ga22Co4Cu4 with T-c = 393 K (achieved 12% strain) by Sozinov et al. (C) 2021 Elsevier B.V. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Design and Real-Time Implementation of a Sliding Mode Observer Utilizing Voltage Signal Injection and PLL for Sensorless Control of IPMSMs(Elsevier - Division Reed Elsevier India Pvt Ltd, 2024-11) Ates, Ertugrul; Tekgun, Burak; Ablay, Gunyaz; Barut, MuratIn this study, a sliding mode observer (SMO) based on high-frequency (HF) voltage signal injection and a phase-locked loop (PLL) is proposed for estimating the extended electromotive force (EEMF), rotor position, and rotor velocity of an interior permanent magnet synchronous machine (IPMSM). This approach addresses real-time estimation challenges associated with standard SMO and PLL at very low speeds and standstill. A reliable and accurate sensorless speed control system for IPMSM is then developed and implemented in real time using the proposed SMO and PLL, covering a wide range of speeds, including low-speed and standstill conditions. The SMO effectively estimates the EEMF, while the PLL extracts the rotor velocity and position based on these estimates. Compared to conventional SMO and PLL methods, real-time results from an 8-pole, 0.4 kW IPMSM demonstrate the superior efficiency of the proposed system.Article Citation - WoS: 40Citation - Scopus: 46A Modeling and Control Approach to Advanced Nuclear Power Plants With Gas Turbines(Pergamon-Elsevier Science Ltd, 2013-12) Ablay, GunyazAdvanced nuclear power plants are currently being proposed with a number of various designs. However, there is a lack of modeling and control strategies to deal with load following operations. This research investigates a possible modeling approach and Load following control strategy for gas turbine nuclear power plants in order to provide an assessment way to the concept designs. A load frequency control strategy and average temperature control mechanism are studied to get load following nuclear power plants. The suitability of the control strategies and concept designs are assessed through linear stability analysis methods. Numerical results are presented on an advanced molten salt reactor concept as an example nuclear power plant system to demonstrate the validity and effectiveness of the proposed modeling and load following control strategies. (C) 2013 Elsevier Ltd. All rights reserved.