Araştırmacılar(23)

• Akaltun, Yunus
• Altintasi, Cagri
• Altunbas, Yasin
• Ayasun, Saffet
• Aydın, Ömer
• Babacan, Yunus
• Büyüktümtürk, Fuat
• Cabuk, Umut Can
• Ertay, Agah Oktay
• Firat, Ishak
• Gecmez, Hilal Sebnem
• Gelen, Aykut Görkem
• Gur, Muslum
• Horoz, Banu
• Ilgin, Fatih Yavuz
• Karaca, Eda
• Müezzinoğlu, Esra Demet
• Ozden, Melih
• Ozgenel, Mehmet Cihat
• Şahin, Mustafa
• Tınğ, Naim Süleyman
• Yildirim, M.A.
• Yildiz, Zerrin

• ArticleYayıncıda açık erişim2026/r/ebyu/17916
  A New High Gain Single-Switch Quadratic Boost Converter with Low Voltage Stress

  Ting, Naim Suleyman; Ipek, Asli Seyda

  Recent progress in DC microgrids necessitates high gain DC-DC converters for effective energy conversion. In this regard, this paper introduces a new high gain single-switch quadratic boost converter (HGS2QBC). This converter, comprising a switch, two inductors, four capacitors, and five diodes, incorporates a voltage multiplier cell (VMC) that provides an 8-times voltage gain at a 0.5 duty cycle. The salient features of the proposed converter are its high voltage gain, having only one switch, low voltage stress across semiconductor devices, and non-pulsating input source current. In addition to its high voltage gain, one of the most significant added-value features of the proposed converter is the presence of a single switch in its structure and the fact that the voltage stress on this switch is half of the output voltage. Furthermore, a 100 W, 200 V, and 20 kHz laboratory prototype is constructed to assess practical viability, and the related experimental results are provided. Experimental analysis confirms the converter's effectiveness in managing voltage and current waveforms across its components, reducing stress on the semiconductor elements and minimizing voltage levels across the diodes. Such design optimizations not only provide superior performance but also offer cost advantages that make the converter economically viable.

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• ArticleYalnız künye2026/r/ebyu/18157
  A new full insulated multi output DC-DC converter for photovoltaic energy regulation and multi-battery charging

  Can, Erol

  The integration of solar energy into electronic devices and battery-charging systems is highly valued due to its status as a clean, environmentally friendly power source. To satisfy energy demands while minimising environmental impact, it is essential to adopt efficient, sustainable technologies. This study introduces a multi-output (dual-inductor, single-capacitor) LLC DC-DC converter designed for battery charging applications, capable of independently charging multiple batteries while reducing input voltage fluctuations from photovoltaic (PV) sources. The proposed converter features independently operated coils for each output channel, preventing long-duration short circuits in the inductors. It achieves high-voltage conversion with reduced output voltage variation, offering greater safety and stability compared to conventional converter designs. A key advantage of this system is its ability to deliver different voltage levels across outputs, enabling flexible, simultaneous charging of various batteries and loads. Initially, circuit modelling and system definition are performed to illustrate these benefits. The dual-inductor, dual-output converter is then evaluated under varying temperatures and irradiance levels during the application phase. Results show reduced ripple levels and increased PV output voltage with lower oscillation while maintaining electrical isolation between batteries and loads.

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• ArticleYayıncıda açık erişim2026/r/ebyu/19216
  Rate-maximized cooperative su selection based on eigenvalues for cognitive radio networks

  Ilgın, Fatih Yavuz

  It is clear that the future of wireless communication systems will face the problem of spectrum scarcity. Cognitive radio systems currently hold a significant position as a solution to this problem. Cognitive radios scan for spectrum gaps and make available for reuse of empty spectrum bands. In this study, we proposed a novel threshold for this method using a different cooperative spectrum sensing method with Standard Condition Number (SCN) for cognitive radios. Detailed simulation studies were included to evaluate the performance of the method. In the simulation studies, different eigenvalue-based sensing methods and energy-based sensing methods were compared using MIMO-OFDM based communication systems. The simulation studies proved the efficiency of the proposed cooperative method.

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• ArticleAçık Erişim2026/r/ebyu/11470
  Photoreceptor Circuit Based on Only Metal–Oxide–Semiconductor Transistors

  Gür, Müslüm; Babacan, Yunus

  In this study, a photoreceptor circuit composed solely of MOS (metal-oxide-semiconductor) transistors was proposed. Currently, researchers in neuromorphic engineering are focusing on mimicking biological nervous systems using silicon devices. The challenges involved in mimicking biological systems are as significant as their potential. These challenges include circuit complexity, low power consumption, computational difficulty, and the challenge of integrating passive components onto a chip. Biologically, millions of neurons consume only a few watts of energy to process information. Therefore, the main reasons challenging researchers in silicon circuit design are reducing power consumption and making it entirely composed of transistors for applicability within the chip. In this study, the modified photoreceptor circuit holds promise due to its low power consumption and entirely transistor-based design. The circuit design was created in LTspice. Permission for real production in TSMC 90-nm technology was granted for the simulation results. The metal-oxide-semiconductor field-effect transistors used in the design were operated below their threshold. The modified circuit is approximately equivalent to the potential change in a biological photoreceptor cell. The modified circuit has been shown to consume approximately 23 times less power compared to the reference circuits. Furthermore, the modified circuit was analyzed under different background light conditions and was found to operate stably. The proposed circuit, composed entirely of MOS transistors, enhances its compatibility with chip designs. This feature reduces its size, which in turn helps lower costs. Content of this journal is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

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• ArticleYalnız künye2026/r/ebyu/11071
  A Cost-Effective Ultra-High-Gain Single-Switch DC–DC Converter with Direct Power Transfer for Low-Voltage PV Applications

  Sahin, Yakup; Ozgenel, Mehmet Cihat; Ting, Naim Suleyman

  This paper presents a novel cost-effective, nonisolated ultra-high-gain single-switch DC–DC converter (UHGS2C) employing a voltage lift (VL) cell and a direct power transfer (DPT) mechanism, specifically designed for low-voltage photovoltaic (PV) applications. The proposed topology achieves an 8× voltage gain at a duty cycle of 0.5 using only a single active switch, three inductors, three capacitors, and five diodes, thereby reducing component count and control complexity compared with conventional high-gain converters. Through the DPT mechanism, a portion of the input energy is transferred directly to the load during the switch-on interval, thereby reducing the energy processed by the magnetic elements and lowering both switch current stress and capacitor voltage ratings. The steady-state analysis confirms that the maximum capacitor voltage is limited to half of the output voltage (VCmax = VO/2), enabling the use of compact, low–voltage-rated capacitors that improve power density and reduce cost. Both continuous and discontinuous conduction modes (CCM/DCM) are analyzed in detail, and a systematic design procedure, along with a comprehensive power loss model, is provided. To validate the theoretical analysis, a 200-W experimental prototype operating at 25-V input, 200-V output, and 50-kHz switching frequency was implemented. The prototype achieves a peak efficiency of 96.4%, while the closed-loop PI control verifies stable line- and load-regulation performance. Comparative results demonstrate that the proposed UHGS2C provides a favorable trade-off among voltage gain, efficiency, component stress, and compactness, making it a strong candidate for renewable energy applications such as PV systems.

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• ArticleYayıncıda açık erişim2026/r/ebyu/11015
  Multi-User Spectrum Sensing for Cognitive Radios: Trace and Eigenvalues Approach

  Ilgin, Fatih Yavuz; Çelik, Husamettin

  In this paper, we propose a novel spectrum detection method for cognitive radios using covariance matrix eigenvalues and its trace. Unlike some traditional eigenvalue and covariance-based detectors, the proposed method is independent of noise power and computationally simple. An optimal threshold calculation approach is also proposed based on the statistical characteristics of the test statistic. This threshold optimization improves detection reliability under different signal-to-noise ratio (SNR) conditions. This common usage improves detection reliability, especially under low SNR conditions and limited sample sizes. Theoretical analyses are provided in detail to characterize the statistical behavior of the proposed test statistic for both hypotheses. Detailed simulation results show that the proposed method is advantageous in terms of computational cost and detection performance.

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• ArticleYayıncıda açık erişim2026/r/ebyu/10917
  Compact and Cost-Efficient Dual-Buck NPC Inverter with Dead-Time Elimination and Shoot-Through Suppression

  Sahin, Yakup; Blaabjerg, Frede; Hatas, Hasan; Ting, Naim Suleyman; Bakan, Ahmet Faruk; Ahmed, Md Rishad

  Dead-time insertion is the conventional method for preventing shoot-through faults in neutral-point-clamped inverters (NPCIs), but it inevitably degrades output-voltage quality, lowers efficiency, and increases control complexity due to dead-time compensation. This article presents a novel transformer-based dual-buck NPCI (T-DB-NPCI) cell that inherently solves this problem at the topology level. The proposed structure not only eliminates the need for dead-time during normal switching transitions but also provides robust hardware suppression of destructive, long-duration shoot-through faults. The proposed cell is designed to safely withstand forced shoot-through faults of up to 2 μs, ensuring high reliability without requiring complex detection algorithms. The topology features a remarkably compact structure comprising only a single high-frequency transformer and one auxiliary diode, enabling all semiconductor devices to operate at only half the DC-link voltage. Furthermore, the streamlined structure allows for the use of standard sinusoidal pulse width modulation (SPWM), significantly reducing control complexity. Comprehensive results from a 425-W prototype achieving 97.4% peak experimental efficiency confirm excellent performance. A comparative analysis reveals an 8% improvement in power density (683 W/kg) and a 6% cost advantage over its closest counterpart. The T-DB-NPCI topology emerges as a highly promising solution where reliability and simplicity are critical.

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• Review ArticleAçık Erişim2026/r/ebyu/10806
  A review of photovoltaic plants and battery energy storage systems in terms of power systems stability

  Çavdar, Bora; Karaca, Eda; Okumuş, Hatice; Nuroğlu, Fatih Mehmet

  Nowadays, the rapid increase in PV plants in power systems has reached a point that may negatively impact power system stability. Battery storage systems have also begun to be integrated into power systems to mitigate the negative effects of non-rotating plants such as PV plants. The expected increase in PV penetration levels and BESS size must be analyzed jointly to address stability issues in power systems. It is evident that existing reviews on the hybrid integration of PV and BESS are limited. This paper aims to contribute to future developments by reviewing the most recent status and potential outcomes of studies related to the impact of PV plants and battery storage system (BESS) units on power system stability. The reviewed studies have been classified to provide valuable insights into the impact of PV plants and BESS units on power system stability. Each classification focuses on the studies in terms of the stability analysis type, the PV/BESS unit combination, the analysis method, the structure of the power system, the PV penetration level, the size of the BESS, whether frequency support is provided, and the use of simulation programs. In the classification of stability, frequency stability and rotor angle (for transients) stability are the most discussed topics. In the review for the units, it was found that studies on the stability of PV power plants were frequently addressed. In addition, studies on BESS and PV-BESS configurations have increased over time. Almost all stability studies focus on time-domain analysis. In addition, modal analysis, which is widely used in small-signal stability studies, is the second most frequently used analysis method in studies. In the studies, the effect of a three-phase short circuit fault on the stability of the system is usually analyzed. Apart from this fault, the implementation of a fault in the load is among the popular cases considered. In the power system classification used, either large or small power systems are usually considered. It is rare for an impact to be considered in both a small and a large power system. Different penetration levels and sizes of PV and BESS units, respectively, are usually analyzed separately in terms of stability. The number of papers investigating the effect of both PV and BESS together on the stability of a power system is quite rare. As a result of the classification on frequency support, it is seen that research on frequency support of PV power plants is handled from similar perspectives, although it has gained popularity recently. When the simulation programs used, which represent the last classification group, are examined, it is observed that DigSilent PowerFactory and MATLAB are generally preferred.

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• ArticleYayıncıda açık erişim2026/r/ebyu/10715
  Decoding the dynamics of daily total global solar radiation: Computational learning strategies powered by explainable AI

  Akiner, Muhammed Ernur; Tınğ, Naim Süleyman; Alsumaiei, Abdullah A.; Katipoğlu, Okan Mert

  This study investigates the prediction of daily total global solar radiation using advanced machine learning and hybrid models. The input variables include various meteorological and environmental parameters such as total precipitation, average snow height, total solar intensity, existing snow height, soil temperature, actual pressure, average temperature, cloudiness, minimum cloud height, and relative humidity. Based on SHAP value analysis, 5 cm Soil Temperature (+67.08) and Total Solar Intensity (+34.76) emerged as the most influential features for the models, while parameters like Current Snow Depth (+0.33) and Average Snow Depth (+0.36) contributed minimally. The analysis spans a period from 2006 to 2022 using daily data. The dataset is divided into 70 % for training and 20 % for validation, with 10 % of the training data allocated for testing. Several models were employed, including AdaBoost, CatBoost, Deep Belief Network (DBN), Light Gradient Boosting Machine (LGBM), Adaptive Neuro-Fuzzy Inference System (ANFIS), Echo State Neural Networks (ESN), and Autoencoder-based regression. According to the analysis results, the Catboost model produces the most accurate predictions with RMSE: 97.25 KW.hr/m2, MAE: 73.64 KW.hr/m2, AIC: 17075, NSE: 0.65 and, KGE: 0.72 values, while the DBN model shows the second best model with RMSE: 98 KW.hr/m2, MAE: 74.48 KW.hr/m2, AIC: 17103, NSE: 0.64 and, KGE: 0.74. The analysis results have the potential to provide information to decision makers and planners, especially in the evaluation of the performance of solar panels, the optimization of agricultural processes, and the development of climate change adaptation strategies.

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• ArticleYayıncıda açık erişim2026/r/ebyu/10578
  Bias-Aware Detection Limits, Calibration Transfer and Matched-Control Robustness Assessment in Dual-Parameter Photonic Refractive-Index and Temperature Sensing: A Coupled Interface-Mode Multilayer Case Study

  Ertay, Agah Oktay; Ertay, Muhammed Mustafa

  Dual-parameter photonic sensors are usually reported through a nominal sensitivity and one detection limit, without stating which statistic that limit is or whether it survives transfer between devices. This computational study supplies that evaluation for one structure, a 36-layer one-dimensional multilayer read in transmission, whose Zak-phase-distinct TiO2/SiO2 photonic-crystal sections enclose a 600 nm analyte cavity and a 500 nm thermo-optic reference cavity, each carrying a 5 nm ITO/5 nm TiO2 nanolaminate insert. Two coupled interface resonances at 1517 and 1651 nm, with loaded Q of 232 and 208 and refractive-index (RI) sensitivities of 90.71 and 329.41 nm/RIU, are inverted by a bounded nonlinear calibration to (Formula presented.) RIU and (Formula presented.) (Formula presented.) ; the temperature channel reports the device temperature. Probability-of-detection limits at 1% false alarm and 95% detection are (Formula presented.) RIU and (Formula presented.) (Formula presented.) ; they are set by the calibration standards and the wavelength reference, not by the linewidth. Transferring one calibration between devices worsens them 81-fold and 203-fold; a three-point per-device correction removes 84–93% of that loss. A trivial control matched on wavelength, Q, transmission, thickness and RI sensitivity shows no topological robustness advantage. Applied to the design itself, the same evaluation shows that the modes are cavity-selected, that hyperbolicity brings no benefit, and that the nanolaminate-free stack is preferred.

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