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Polen stores all academic resources—such as books, articles, theses, papers, reports, and research data—directly or indirectly published by the academic and administrative staff and students of Istanbul Technical University in a digital environment in accordance with international standards. It facilitates monitoring the university’s academic performance, ensures the long-term preservation of resources, and provides open access to publications in compliance with copyright regulations to enhance their impact.

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Açık Ders Kaynakları 30
İTÜ'de verilen bazı derslerin video kayıtlarını içermektedir.
Akademik Çalışmalar 45652
İTÜ'de yapılan akademik çalışmaları içermektedir.
Arşiv Koleksiyonu 603
Çeşitli birimlerde yer alan arşiv koleksiyonunu içermektedir.
Sunumlar 42
Kurum içinde yapılan çeşitli sunumların çıktılarını içermektedir.
Temel Kayıtlar 2825
Master Data

Recent Submissions

Access status: Open Access ,
Modeling and simulation of a hydraulic booster system for aircraft fight control applications
(Graduate School, 2026-06-19) Elmalı, Abdülkadir; Baytaş, Ayşe Filiz; 301201045; Energy Science and Technology
Aircraft hydraulic power systems (HPS) are widely employed in modern aircraft to generate, transmit, and control the high-power levels required by flight control surfaces, landing gear mechanisms, braking systems, and other safety-critical subsystems. A typical aircraft HPS comprises a hydraulic power source—most commonly engine-driven or electrically driven pumps—together with fluid reservoirs, filters, pressure relief and check valves, accumulators, distribution lines, control valves, and hydraulic actuators. Operating as an integrated network, these components ensure reliable force transmission over a wide range of load cases and environmental conditions. Owing to their high power density, robustness, and operational maturity, hydraulic systems remain a fundamental element of both conventional and advanced aircraft architectures. Despite these advantages, aircraft HPS exhibit several inherent limitations that can affect overall system performance and controllability. Pressure losses within distribution lines, nonlinear valve flow characteristics, and delays in dynamic response may reduce system effectiveness, particularly under high aerodynamic loading. As flight speed and maneuvering demands increase, the forces acting on control surfaces rise significantly, resulting in increased pilot effort or higher actuator force requirements in non-assisted configurations. These effects become especially pronounced during demanding flight conditions, where rapid and precise control surface actuation is essential. To address such challenges, hydraulic booster systems are commonly integrated into flight control architectures to amplify input forces, improve dynamic response, and enhance system stability margins. This thesis focuses on the modeling and simulation of a hydraulic booster system as a functional subsystem of an aircraft HPS used in flight control applications. The booster system is examined in terms of its contribution to force amplification, pressure regulation, and overall dynamic performance. In order to enable focused analysis while maintaining physical relevance, the booster is isolated from the complete aircraft hydraulic network. This approach allows a simplified yet representative system model to be established, facilitating detailed investigation of booster behavior and its interaction with control inputs. A physics-based mathematical model of the hydraulic booster system is developed using lumped-parameter modeling (LPM) techniques. The governing equations describing fluid continuity, orifice flow, actuator force balance, and fluid compressibility are formulated based on fundamental fluid mechanics principles. The model is implemented in a one-dimensional system-level simulation environment, where appropriate simplifications are introduced to reduce complexity while preserving the dominant physical effects. Such simplifications enable efficient xx numerical simulation and support parametric studies without compromising the qualitative accuracy of system behavior. The developed simulation model is benchmarked against a reference study from the open literature to evaluate its structural consistency and dynamic response trends. Comparative analyses focus on pressure build-up characteristics, actuator response, flow rate from the system and force amplification behavior under comparable operating conditions. Preliminary simulation results indicate that the inclusion of a hydraulic booster system leads to improved pressure response and reduced required control input forces when compared to a non-boosted configuration. These trends are consistent with observations reported in the literature and highlight the potential of booster systems to enhance overall flight control effectiveness. Furthermore, several parametric evaluation studies are conducted to investigate the influence of key hydraulic system parameters on overall system behavior. The effects of accumulator volume, accumulator pressure level, system flow rate, and varying consumer loads are analyzed under transient operating conditions. The results show that increasing accumulator capacity and system flow rate generally improve pressure stability and dynamic response, while the hydraulic booster system provides additional support under higher consumer load conditions. These analyses also demonstrate that beyond certain parameter ranges, the improvement in system performance becomes limited, indicating diminishing returns and emphasizing the importance of balanced system design. Although the present study is primarily motivated by aircraft flight control applications, the proposed modeling approach and findings are not limited to fighter aircraft. The developed methodology is also applicable to other platforms, including fixed-wing transport aircraft, helicopters, unmanned aerial vehicles, and high-load industrial hydraulic systems, where force amplification and dynamic response are critical performance considerations. Future work will focus on further refinement of the simulation model, improved parameter identification, and extension of the analysis to a wider range of operating conditions. Additional studies may include control system integration, assessment of nonlinear effects, and correlation with experimental or higher-fidelity reference data to enhance the reliability and applicability of the proposed modeling framework.
Access status: Metadata only ,
Comparative Analysis of PINN Architectures for Solving the Non-Dimensionalized Pennes’ Bioheat Equation in Non-Homogeneous Domain
(IEEE, 2025-07-14) Hasan, Yazar; Shaikhah, Alkhadhr; Gulsah, Yildiz; Mohamed, Almekkawy; Elektronik ve Haberleşme Mühendisliği Bölümü; Yıldız, Gülşah; Altıntaş, Gülşah Yıldız
Accurate modeling of heat transfer in biological tissues is essential for biomedical applications such as thermal therapies. The Pennes' bioheat equation provides a fundamental framework for understanding thermal dynamics in tissues; however, solving it in non-homogeneous domains remains computationally challenging. In this paper, we employ Physics-Informed Neural Networks (PINNs) to solve the non-dimensionalized Pennes' bioheat equation in a non-homogeneous tissue environment, incorporating variations between muscle and fat through a smooth transition function. To increase stability and efficiency, we introduce a non-dimensionalization process that scales spatial, temporal, and thermal parameters based on characteristic values. A custom PINN framework is implemented to simulate the Pennes' bioheat equation using NVIDIA Modulus, and different neural architectures are evaluated across various collocation densities. Model performance is benchmarked against a Finite Difference Method (FDM) solution by assessing different metrics. Our findings reveal that PINNs demonstrate superior training stability especially with Fourier-based architectures, and reduced loss compared with other architectures. These results show the effectiveness of non-dimensionalization and PINNs in advancing computational models for biomedical simulations and therapeutic applications.Clinical Impact- Optimizing thermal treatments, such as laser-induced thermotherapy (LITT), cryosurgery, and hyperthermia treatment, requires an understanding of heat transmission in biological tissues. This study offers an efficient method for modeling tissue architectures using PINNs to solve the Pennes' bioheat equation in non-homogeneous environments.
Access status: Metadata only ,
A Hexa-Band Frequency Selective Surface Design for Multi-Band Parabolic Reflector Antennas
(IEEE, 2025-07-13) Mehmet Kopar; Orcun Kiris; Serkan Simsek; Elektronik ve Haberleşme Mühendisliği Bölümü; Şimşek, Serkan
This study presents a multi-band Frequency Selective Surface (FSS) unit cell element design which is inspired by Anatolian motifs and suitable for use as a sub-reflector for parabolic reflector antennas. The FSS unit cells are designed by placing two different motif shapes on different surfaces of a substrate, which are subsequently rotated by 90° and placed sequentially in order to be useful across multiple frequency bands. The proposed FSS transmits electromagnetic (EM) waves over the frequency ranges of 7.25-7.75 GHz and 7.9-8.4 GHz while reflecting waves over 14.4-14.83 GHz, 15. 15-15.35 GHz, 20.2-21.2 GHz and 30 - 31 GHz. Also, it performs low-loss characteristics up to 40° incidence angle. The proposed unit cell is very convenient for use in the design of an FSS based sub-reflector structure to implement on a hexa-band (3 transmitter, 3 receiver), multi-functional, compact parabolic reflector antenna applications. © 2025 IEEE.
Access status: Metadata only ,
Comment on egusphere-2025-2114
(Copernicus GmbH, 2025-07-09) Avrasya Yer Bilimleri Enstitüsü; Ilıcak, Mehmet
Access status: Metadata only ,
Spatio-temporal analysis of air pollution from geothermal power plants: insights from ground and satellite observations
(Springer Science and Business Media LLC, 2025-07-08) Merve, Aydin; Burcak, Kaynak; Çevre Mühendisliği Bölümü; Tezel, Burçak Kaynak
Türkiye is ranked fourth worldwide in terms of electricity generation from geothermal power plants (GPPs). With recent legal restrictions about GPPs, additional H2S measurements were started along with routine criteria air pollutants at selected air quality monitoring stations (AQMSs) in regions with GPPs in western Türkiye. This study aims to analyze the relationship between GPP-associated variables and air pollutants for 2022, and focuses on four regions (Region-1-4) determined according to GPP clusters with available H2S and SO2 measurements in close proximity. Ground-based (gr) H2S, SO2 measurements, TROPOMI SO2, NO2, HCHO, CH4, and IASI NH3 retrievals were used along with GPP electricity production (EP) and meteorological measurements. The higher EP, gr-H2S, and gr-SO2 values were observed during winter, spring and fall in all regions with similar temporal patterns. The wind speed and direction analysis showed that higher gr-H2S and gr-SO2 concentrations were associated with GPP locations, especially in Region-1: All (E, ENE) and Region-2: Germencik (NW, WNW, and W) indicating transport. Daily gr-H2S and gr-SO2 correlations were significant in all regions with highest in Region-2: Germencik (R = 0.63) followed by Region-1: All (R = 0.58). Seasonal and monthly correlations showed highest in fall season, in particular November. Spatial distributions of SO2 and NH3 satellite retrievals indicated particularly higher levels around GPP regions in spring and autumn, specifically in March, April, October, and November in which total EP were also higher. Finally, correlations of monthly total EP with pollutants of focus showed positive relationship with gr-H2S, gr-SO2, and SO2 retrievals, and negative relationship with NH3, and HCHO.