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Açık Ders Kaynakları 30
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Akademik Çalışmalar 45188
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Arşiv Koleksiyonu 603
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Sunumlar 42
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Temel Kayıtlar 2825
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Access status: Open Access ,
TOK'2019 Ulusal Konferansı
(İstanbul Teknik Üniversitesi, 2019) Elektrik Elektronik Fakültesi; Taşcıkaraoğlu, Akın; Taşcıkaraoğlu, Fatma Yıldız; Özdemir, Faruk; Eksin, İbrahim
Ülkemizde de bu konunun önemi oldukça erken fark edilmiştir. Prof. M.Münir Ülgür, 1953 yılında İstanbul Teknik Üniversitesi (İTÜ) Elektrik Fakültesi bünyesinde “Servomekanizmalar” dersini vermeye başlamıştır. Benzer biçimde yine İTÜ bünyesinde Prof. Dr. Mehmet Nimet Özdaş da Makine Fakültesi’nde “Otomatik Kontrol” dersini açmıştır. Daha sonra, bu iki değerli profesörün gayretleri ile 1958 yılında TOK, IFAC’a üye olarak ve IFAC statüsünde kurulmuştur. 02 Mayıs 1990 günlü ve 20506 sayılı Resmi Gazete’de yayımlanan yönetmeliği ile de “Otomatik Kontrol Türk Milli Komitesi” TOK adını alarak milli bir kimlikle daha kapsamlı bir kurum haline gelmiştir. TOK kurumunun amacı, otomatik kontrol bilim ve teknolojisinin bütün sistemlerde kurumsal ve uygulamalı olarak ilerlemesini teşvik etmek, ulusal ve uluslararası ilgili tüm kuruluşlarla bu alanda ortak çalışmalar yürütmektir. TOK, bu amacı doğrultusunda ulusal ve uluslararası konferans, sempozyum,çalıştay gibi toplantılar düzenler ve düzenlenmesine destek verir. TOK ticari bir kuruluş değildir ve siyasetle uğraşmaz. Her geçen yıl genç bilim insanlarının, mühendislerin, tıp doktorlarının ve diğer ilgili araştırıcı ve uygulamacıların kontrol konularına artan ilgisi sevindiricidir. Bu arkadaşlarımızın, zaman içinde TOK ve IFAC bünyesinde daha katılımcı ve güçlü bir konuma gelmelerini ve de daha etkin çalışmalar yapabilmelerini arzu etmekteyiz. Bu konuda üzerine düşen görev ne ise yapmaya hazır olduğumuzun bilinmesini isteriz. Böylece ülkemizi uluslararası ölçekte daha etkin bir konuma getirmeyi ve daha geniş çaplı uluslararası konferansları ve kongreleri ülkemizde gerçekleştirmeyi hedefliyoruz.
Access status: Open Access ,
TOK 2021 Otomatik Kontrol Türk Milli Komitesi Ulusal Kongresi : Bildiriler Kitabı
(İstanbul Teknik Üniversitesi, 2021) Elektrik Elektronik Fakültesi; Atan, Özkan; Özok, Halil İbrahim; Kutlu, Fatih; Silahtar, Onur; Kutlu, Fatih; Eksin, İbrahim; Söylemez, Mehmet Turan
TOK kurumunun amacı, otomatik kontrol bilim ve teknolojisinin bütün sistemlerde kurumsal ve uygulamalı olarak ilerlemesini teşvik etmek, ulusal ve uluslararası ilgili tüm kuruluşlarla bu alanda ortak çalışmalar yürütmektir. TOK, bu amacı doğrultusunda konferans, sempozyum, çalıştay gibi toplantılar düzenler ve düzenlenmesine destek verir. TOK, ulusal toplantıların yanı sıra, üyesi olduğu “International Federation of Automatic Control-IFAC” adına uluslararası bilimsel toplantıların ülkemizde düzenlenmesinde öncülük görevini sürdürmektedir. Bu bağlamda, isimlerini söylemeyeceğim kadar çok değerli meslektaşlarım tarafından ülkemizde birçok etkinlik düzenlenmiştir. Bu organizasyonların hemen hepsi de IFAC nezdinde çok büyük bir beğeni elde etmiştir. Son yıllarda genç bilim insanlarının, mühendislerin, tıp doktorlarının ve diğer ilgili araştırıcı ve uygulamacıların kontrol konularına artan ilgisi sevindiricidir. Bu arkadaşlarımızın, zaman içinde TOK ve IFAC bünyesinde daha verimli ve daha güçlü bir konuma gelmesini, böylece daha büyük ve daha çok sayıda uluslararası konferansları ülkemizde gerçekleştirmek amaçlamaktayız.
Access status: Metadata only ,
Flow through electrolysis of h₂s for hydrogen production
(ITU Graduate School, 2026) Nazari, Faezeh; Sarıoğlan, Alper; 506221031; Chemical Engineering
The rapidly increasing global demand for clean and sustainable energy carriers has positioned hydrogen as a central component of future energy systems. Hydrogen is widely regarded as a promising fuel due to its high gravimetric energy density and the absence of carbon emissions at the point of use. However, the environmental and economic sustainability of hydrogen production routes remains a critical challenge. Among the available technologies, conventional water electrolysis is one of the most mature and scalable methods, yet it suffers from inherently high energy consumption. This limitation arises primarily from the sluggish kinetics and high thermodynamic potential of the oxygen evolution reaction (OER), which requires a minimum potential of 1.23 V under standard conditions and often significantly higher overpotentials in practical systems. In response to these challenges, alternative electrochemical pathways have attracted increasing attention, particularly reactions that can replace the OER with more kinetically favorable anodic processes. One such promising alternative is the electrochemical splitting of hydrogen sulfide (H₂S). Hydrogen sulfide is a highly toxic and corrosive gas that is abundantly produced as a byproduct in petroleum refining, natural gas processing, wastewater treatment, and geothermal operations. In addition to its environmental hazards, H₂S represents an underutilized hydrogen-rich resource. From a thermodynamic perspective, the sulfide oxidation reaction (SOR) occurs at a much lower equilibrium potential (~0.14 V vs. RHE in alkaline media) compared to OER, enabling hydrogen production at significantly reduced cell voltages. Consequently, H₂S electrolysis offers a dual benefit: sustainable hydrogen generation and effective mitigation of sulfur pollution. This thesis systematically investigates the electrochemical conversion of H₂S to hydrogen using cobalt phthalocyanine (CoPc)–based electrocatalysts. The primary focus is placed on understanding the effects of catalyst modification, electrolyte composition, and electrochemical cell configuration on catalytic activity, energy efficiency, and system scalability. Cobalt phthalocyanine was selected as the catalyst precursor due to its favorable redox characteristics, earth abundance, relatively low cost, and well-defined molecular structure containing metal–nitrogen coordination sites known to be active for redox reactions. Moreover, the molecular framework of CoPc allows for controlled thermal transformation into catalytically active carbon-based materials. To enhance catalytic performance, CoPc was subjected to thermal treatment at 500°C and 700°C under an inert atmosphere, yielding two modified catalysts denoted as CoPc-500 and CoPc-700, respectively. Thermogravimetric analysis (TGA) confirmed distinct decomposition stages associated with ligand degradation and carbonization. Structural and morphological characterization using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) surface area analysis revealed substantial differences between the two materials. CoPc-500 retained partial molecular features of the phthalocyanine macrocycle while developing a highly porous structure with a significantly increased specific surface area. In contrast, CoPc-700 exhibited complete decomposition of the organic ligand, resulting in an amorphous carbon matrix embedded with Co–N–C active sites, which are widely recognized for their high electrocatalytic activity in redox reactions. Electrochemical performance was evaluated using three-electrode configurations, H-type cells, and membrane electrode assembly (MEA) systems in alkaline sulfide-containing electrolytes. Linear sweep voltammetry (LSV) and cyclic voltammetry (CV) measurements demonstrated that thermal treatment markedly improves catalytic activity by lowering onset potentials and enhancing current densities. Among all investigated materials, CoPc-700 consistently showed the best performance, exhibiting the lowest onset potential and the highest current response. In a 0.3 M Na₂S electrolyte, the onset potential of CoPc-700 was approximately 200 mV lower than that of untreated CoPc, while the peak current density increased by more than 40%, indicating a substantial enhancement in reaction kinetics. The role of the electrolyte was found to be critical for efficient operation. Experiments conducted in Na₂S-free alkaline electrolytes resulted in significantly higher polarization losses and negligible anodic activity, underscoring the essential role of sulfide ions in facilitating low-voltage hydrogen production. Electrochemically active surface area (ECSA) analysis revealed that CoPc-700 possessed the highest density of accessible active sites, despite having a lower total BET surface area than CoPc-500. This observation highlights that catalytic performance is governed more by the chemical nature and accessibility of active sites rather than by surface area alone. MEA experiments further validated the practical applicability and scalability of the system. The use of thermally modified CoPc catalysts enabled notable reductions in full-cell voltage, particularly at elevated operating temperatures. Increasing the operating temperature from 25°C to 65°C led to pronounced decreases in onset potential and overall cell voltage for all catalysts, reflecting enhanced reaction kinetics and improved mass transport. Ultraviolet–visible (UV–Vis) spectroscopy confirmed the formation of soluble polysulfide species during electrolysis, while Faradaic efficiency measurements verified effective hydrogen generation with minimal sulfur crossover or parasitic reactions. In summary, this work demonstrates that thermally modified cobalt phthalocyanine, especially CoPc-700, is a highly effective and scalable electrocatalyst for hydrogen production via H₂S electrolysis. By enabling low-voltage operation, reducing overall energy consumption, and utilizing sulfur-rich feedstocks such as simulated seawater, this approach presents a promising pathway toward sustainable hydrogen generation while simultaneously addressing sulfur-related environmental challenges. Future research should focus on long-term operational stability, mitigation of sulfur-induced catalyst passivation, and optimization of electrode and cell architectures to further enhance current density, durability, and industrial viability.
Access status: Open Access ,
Investigation of thermal and mechanical properties of graphene oxide and reduced graphene oxide reinforced polypropylene composites
(ITU Graduate School, 2026) Gürer, Cemile; Güner, Fatma Seniha; 506241036; Chemical Engineering
Polymer-based composite materials, thanks to their low density, easy formability, broad design possibilities, high corrosion resistance, and cost-effective production processes, are among the preferred material groups in many engineering fields, particularly in the automotive and aerospace sectors, for structural applications. These properties make them a significant alternative to metal-based materials, particularly in modern engineering applications where lightweight strength and durability are sought together. Polypropylene (PP) is a thermoplastic polymer widely used in such applications. While notable for its advantages such as thermal stability, ease of processing, low density, cost-effectiveness, and chemical resistance, it also presents some disadvantages, such as low hardness, limited impact resistance, and limited mechanical performance. These limitations make polypropylene inadequate on its own for some high-performance applications. To compensate for these weaknesses, reinforcing PP with various micro- and nano-scale fillers to improve its physical and mechanical properties has become a growing area of research in recent years. Nano-reinforcements, in particular, have the potential to significantly improve composite properties because they provide higher surface area and interfacial interaction compared to conventional microfillers. In the literature, many nanostructures, such as graphene and its derivatives, clay-based nanomaterials, and metal oxides, are used to improve the mechanical, thermal, rheological, and electrical properties of polymer matrices. Among these, graphene and its derivatives stand out due to their high modulus and tensile strength, exceptional electrical conductivity, and chemical stability. Graphene, a two-dimensional material composed of a single layer of carbon atoms arranged in a hexagonal arrangement, theoretically possesses very high Young's modulus and tensile strength. However, pure graphene, due to its hydrophobic structure, exhibits limited interaction with polymer matrices. To overcome this problem and provide better compatibility with the matrix, graphene oxide (GO) was developed. GO is obtained by chemically modifying the graphene structure with oxygen-containing functional groups such as epoxy, hydroxyl, and carbonyl. These functional groups impart hydrophilic character to GO, allowing for better dispersion within the polymer matrix. Thus, GO can act not only as a filler but also as a binder, enhancing interfacial interaction with the matrix. Reduced graphene oxide (rGO), obtained by chemical or thermal reduction of GO, is a derivative with reduced oxygen content and a more conductive structure. rGO exhibits higher electrical and mechanical performance compared to GO and also has a more hydrophobic surface. This property provides better compatibility with nonpolar polymers such as PP, particularly contributing to enhanced interfacial bonding. Thanks to its two-dimensional hexagonal honeycomb structure, rGO can directly influence properties such as load-carrying capacity, thermal stability, and crystallization behavior. Furthermore, some literature studies have demonstrated that rGO can act as a crystallization nucleus, thereby regulating the crystal structure of the matrix, further enhancing thermal and mechanical performance. In conclusion, carbon-based nanomaterials such as GO and rGO have the potential to significantly improve the performance of polymer-based composites, even at low additive ratios. These additives not only improve material properties but also expand the application areas of polymers in advanced engineering applications. Therefore, systematically investigating the effects of GO and rGO in PP matrix composites is an important research topic from both academic and industrial perspectives. In this study, PP nanocomposites prepared with GO and rGO additives at 1%, 3%, and 5% by weight were characterized in detail. PP/GO and PP/rGO composites with 10% additive ratios were used as a masterbatch. These composite materials were mixed with virgin PP at appropriate ratios to prepare new composite materials with the targeted 1%, 3%, and 5% by weight ratios. All mixing operations were carried out using a continuous production twin-screw extruder with a six-stage temperature profile. This method provided a significant advantage in ensuring homogeneous distribution. The resulting materials were analyzed for their crystallographic structures, mechanical and thermal properties, morphologies, and flame resistance. The microstructural properties of the produced nanocomposites were evaluated using X-ray diffraction analysis (XRD), and structural changes were determined by their degree of crystallinity. Furthermore, the distribution of fillers within the polymer matrix was examined using scanning electron microscopy (SEM), and the homogeneity and agglomeration tendencies of the additives were observed. Thermal properties were determined using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the decomposition temperatures, melting, and crystallization temperatures of the composites were determined. Furthermore, tensile, bending, and impact tests were conducted as part of the mechanical performance assessment, and the effects of additive ratios on strength were compared. Dog-bone and flat bar specimens prepared using a mini-injection molding machine were used for mechanical tests and flammability testing. The combustion behavior of the prepared nanocomposites was also tested. According to the UL-94 standard, the composites are classified as V2 flammability class. The addition of GO and rGO has shown improvement in the flammability properties of pure PP classified as NR. Potential interactions between the components were evaluated using FTIR analysis. All analyses revealed that adding both GO and rGO additives at specific ratios to the PP matrix significantly improved the thermal stability and mechanical strength of the composites. Specifically, the highest increases in tensile strength and degradation temperatures were recorded in rGO-added samples. This was attributed to rGO's better interaction with the PP matrix due to its lower oxygen-containing functional groups and more hydrophobic structure compared to GO. DSC analysis results revealed that GO and rGO improved the crystallization behavior of pure polypropylene and increased nucleation efficiency. SEM images showed that both rGO and GO exhibited homogeneous distribution within the PP matrix. This thesis demonstrates that nanostructures such as GO and rGO can significantly improve the material properties of PP-based composites, even at low addition rates. These findings enhance the potential of PP-based nanocomposites in various engineering applications, particularly in the automotive, aerospace, packaging, and construction sectors, and contribute to the design of new materials in these areas. Keywords: Polypropylene, Graphene oxide, Reduced graphene oxide, Polymer composites, Nanocomposites, Thermal properties, Mechanical properties.
Access status: Open Access ,
Selimpaşa ve çevresinin tarihi katmanları ve İstanbul'un iaşe sistemindeki rolü
(İTÜ Lisansüstü Eğitim Enstitüsü, 2026) Karagülle, Nil Ceren; Ar, Bilge; 502221102; Mimarlık
The study aimed to integrate historical research, spatial and architectural analysis, archival documentation, cartographic materials, and photographic evidence. Selimpaşa possesses a multilayered settlement history that extends from prehistoric times to the present. Archaeological findings indicate continuous human occupation from the Neolithic and Chalcolithic periods through the Early Bronze Age, demonstrating the long-term significance of the site within the Thracian region. During antiquity and the Byzantine period, the settlement was known as Epivates (Epibatai) and functioned as an important coastal community within the hinterland of Constantinople. Historical sources, including hagiographic narratives and Byzantine chronicles, associate Epivates with prominent religious figures such as Saint Paraskevi and document its involvement in political and military events, particularly during the late Byzantine period. The presence of fortifications, elite residences of high ranked military officer Alexios Apokaukos, and religious structures indicates its strategic and symbolic importance within the regional defensive and administrative system. Following the Ottoman conquest, the settlement came under Ottoman rule and was known as Bigados. Ottoman administrative records, legal documents, and customs regulations demonstrate that Bigados was integrated into the imperial economic and administrative framework, particularly within the maritime and coastal trade networks of the Marmara region. The village's economy was primarily based on agriculture, fishing, and viticulture, which formed the backbone of its contribution to the supply networks that sustained Istanbul. Agricultural production in the surrounding hinterland was transported to the capital via both maritime and land routes, highlighting the role of small and medium-sized coastal settlements in supporting the metropolitan economy. Selimpaşa, in this context, functioned as a peripheral yet essential node within these regional networks. During the nineteenth century, Selimpaşa (Bigados) experienced significant social, institutional, and spatial transformations, particularly under the influence of its Greek population. The expansion of religious and educational institutions during this period reflects both the Tanzimat reforms and broader modernization processes within the Ottoman Empire. The establishment of the Arhigenya Schools and associated facilities, funded by Sarandi Arhiyeni and his family foundation, transformed Selimpaşa into a regional center of education and culture for the Greek community of Thrace. Multiple churches, schools, and communal buildings were constructed, contributing to the formation of a distinct urban fabric characterized by monumental religious architecture and educational complexes. These structures represent a significant component of Selimpaşa's architectural heritage and illustrate the interaction between local communities and imperial reforms. The study also examines administrative and demographic changes over time. Throughout the Ottoman period, Selimpaşa's administrative affiliation shifted between Silivri, Büyükçekmece, and Çatalca, reflecting broader provincial reforms and administrative restructuring. Population records and archival documents indicate fluctuations in population size and ethnic composition, particularly during the late Ottoman period. These changes are interpreted in relation to political, economic, and social dynamics in the region, including migration patterns, economic opportunities, and administrative reforms. A major turning point in Selimpaşa's history occurred with the population exchange between Greece and Turkey following the establishment of the Republic of Turkey in 1923. As part of the compulsory population exchange by Treaty of Lausenne, the Greek Orthodox population of Bigados was relocated to Greece, in particular to Neoi Epivates in Thessaloniki formerly known as Bahtçeçiftlik, while Muslim Turkish populations from Greece were resettled in the area. This process led to a profound transformation in the demographic, cultural, and spatial structure of the settlement. The village was renamed Selimpaşa, and many religious and educational buildings lost their original functions, were abandoned, or were repurposed for new uses. The population exchange represents a critical rupture in Selimpaşa's historical continuity, reshaping its social identity and built environment. The architectural heritage of Selimpaşa constitutes a central focus of the research. The study documents a range of religious, educational, and infrastructural structures, including churches, schools, fountains, and industrial buildings such as wineries. Among these, the Church of Saint Georgios is a prominent surviving structure that was later converted into a mosque, illustrating the adaptive reuse of religious architecture in the post-exchange period. Other significant structures, such as the Church of Saint Paraskevi and the Arhigenya School complex, are analyzed in terms of their architectural features, historical significance, and current state of preservation or loss. Water infrastructure, including monumental fountains, is also examined as an important element of local urban development and public architecture. The research situates Selimpaşa within the broader geographical and historical context of the Thracian region and Istanbul's hinterland. Neighboring settlements such as Silivri, Çatalca, and Büyükçekmece are analyzed as interconnected nodes within a regional network that supported the capital. The historical development of Silivri (ancient Selymbria) is traced from its foundation by Megarian colonists through the Byzantine and Ottoman periods, emphasizing its strategic location, defensive structures, and administrative transformations. Similarly, Çatalca's role as an agricultural and administrative center, as well as its shifting political status between Byzantine and Ottoman control, is examined. These regional analyses provide a framework for understanding Selimpaşa's position within the spatial and economic hierarchy of the hinterland. The concept of urban and imperial provisioning forms a key analytical framework in this research. The study explores how agricultural production, trade routes, administrative mechanisms, and transportation networks functioned together to ensure the continuous supply of goods to Istanbul. Selimpaşa is interpreted as a peripheral yet integral component of these provisioning networks, contributing agricultural products and participating in regional trade systems facilitated by both maritime routes. By looking at Ottoman archival documents, traveler accounts, and historical maps, the research aimed to reconstruct these networks and demonstrate the continuity and transformation of economic structures from the Byzantine to the Ottoman period. Methodologically, the study combines historical research with spatial and architectural analysis. Archival sources, including Ottoman administrative records, population registers, and legal texts, are complemented by secondary literature, archaeological reports, historical maps, and photographic documentation. Comparative analysis of historical and contemporary maps and images is employed to trace changes in settlement patterns, urban morphology, and architectural fabric. This interdisciplinary approach allows for a comprehensive understanding of Selimpaşa's historical trajectory and its role within regional and imperial systems. In conclusion, this research provides a multidimensional analysis of Selimpaşa as a historically layered settlement within the Thracian hinterland of Istanbul. By examining its archaeological origins, Byzantine and Ottoman history, demographic transformations, architectural heritage, and role within regional provisioning networks, the study contributes to a broader understanding of coastal settlements and urban relations in the history of Istanbul. Selimpaşa is presented not merely as a peripheral locality but as an active participant in the economic, social, and spatial systems that sustained the imperial capital across centuries. The findings show the importance of small and medium-sized settlements in shaping regional historical processes and emphasize the need for further research and conservation efforts to preserve Selimpaşa's cultural and architectural heritage.