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Effect of Geometry and Fiber Type on Energy Absorption in Polymer Based Composite Crash Boxes: An Experimental Study
(Wiley, 2025) Kosedag, Ertan; Araz, Zumray; Erkek, Baran
Vehicle crash boxes, mounted on the chassis before the bumper, absorb impact energy to protect passengers, but their metal construction adds weight, prompting increased research into lightweight composite alternatives with comparable strength. In this study, energy absorption values (EA), specific energy absorption (SEA), peak forces (PF) and crashing force efficiency (CFE) of carbon fiber, glass fiber, and aramid fiber reinforced composite crash boxes with epoxy resin matrix were compared. Composite crash boxes with different geometries were fabricated using vacuum infusion method in three different geometries: hexagonal, circle, and square. Unlike hand lay-up and prepreg winding methods, vacuum infusion method was chosen because it provides homogeneous distribution of epoxy resin. The crashworthiness of the samples was evaluated through quasi-static compression tests. The best energy absorption performance was obtained with the hexagonal carbon fiber-reinforced composite crash box (246.17 J), corresponding to a specific energy absorption of 8.57 J/g. Although aramid fiber-reinforced specimens showed lower energy absorption, they exhibited the highest crash force efficiency among all tested configurations. These results confirm the significant influence of both fiber type and geometry on the crashworthiness of polymer-based composite crash boxes. The study highlights that hexagonal geometry consistently provided superior energy absorption across all fiber types, while carbon fiber-reinforced composites demonstrated the best overall mechanical performance, making them strong candidates for lightweight crashworthiness applications.
Effect of Geometry and Fiber Type on Energy Absorption in Polymer Based Composite Crash Boxes: An Experimental Study
(Wiley, 2025) Kosedag, Ertan; Araz, Zumray; Erkek, Baran
Vehicle crash boxes, mounted on the chassis before the bumper, absorb impact energy to protect passengers, but their metal construction adds weight, prompting increased research into lightweight composite alternatives with comparable strength. In this study, energy absorption values (EA), specific energy absorption (SEA), peak forces (PF) and crashing force efficiency (CFE) of carbon fiber, glass fiber, and aramid fiber reinforced composite crash boxes with epoxy resin matrix were compared. Composite crash boxes with different geometries were fabricated using vacuum infusion method in three different geometries: hexagonal, circle, and square. Unlike hand lay-up and prepreg winding methods, vacuum infusion method was chosen because it provides homogeneous distribution of epoxy resin. The crashworthiness of the samples was evaluated through quasi-static compression tests. The best energy absorption performance was obtained with the hexagonal carbon fiber-reinforced composite crash box (246.17 J), corresponding to a specific energy absorption of 8.57 J/g. Although aramid fiber-reinforced specimens showed lower energy absorption, they exhibited the highest crash force efficiency among all tested configurations. These results confirm the significant influence of both fiber type and geometry on the crashworthiness of polymer-based composite crash boxes. The study highlights that hexagonal geometry consistently provided superior energy absorption across all fiber types, while carbon fiber-reinforced composites demonstrated the best overall mechanical performance, making them strong candidates for lightweight crashworthiness applications.
Fourier analysis-based automatic test pattern generation for combinational circuits
(Ieee, 2015) Ayav, Tolga; Ayav, Tolga; Bilgisayar Mühendisliği Bölümü
Fourier analysis of boolean functions has attracted great attention from computer scientists in the last decade but it still has few application areas. This work presents a Fourier analysis-based automatic test pattern generation method for combinational circuits.
Citation - WoS: 5
Heme binding constricts the conformational dynamics of the cytochrome: Heme binding cavity
(Amer Chemical Soc, 2012) Akdogan, Yasar; Anbazhagan, Veerappan; Hinderberger, Dariush; Schneider, Dirk
Cytochrome b(559)' is a transmembrane protein formed by homodimerization of the 44-residue PsbF polypeptide and noncovalent binding of a heme cofactor. The PsbF polypeptide can dimerize in the absence and presence of heme. To monitor structural alterations associated with binding of heme to the apocytochrome, we analyzed the apo- and holo-cytochrome structure by electron paramagnetic resonance spectroscopy. Spin labeling of amino acids located close to the heme binding domain of the cytochrome revealed that the structure of the heme binding domain is unconstrained in the absence of heme. Heme binding restricts the conformational dynamics of the heme binding domain, resulting in the structurally more constricted holo-cytochrome structure.
Citation - Scopus: 1
Hydrothermal Liquefaction of Sinapis Arvensis Biomass Using TiO2-Supported Metal Catalysts: A Study on Bio-Oil Yield and Composition
(Elsevier, 2026) Durak, Halil; Genel, Salih; Genel, Yasar
The development of catalytic systems for hydrothermal liquefaction (HTL) is crucial for transforming lignocellulosic biomass into biofuels with high energy density. This research investigates the HTL process of Sinapis arvensis biomass using TiO2-supported catalysts, specifically Fe, Al, and Fe-Al, at temperatures from 275-325 degrees C. The catalysts were synthesized through incipient wetness impregnation and characterized using techniques like X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and inductively coupled plasma optical emission spectrometry (ICP-OES) to evaluate element distribution and surface chemistry. Findings show that the Al/TiO2 catalyst boosted lighter bio-oil production via acid-catalyzed dehydration and decarboxylation, while the Fe/TiO2 catalyst favored heavier oils through redox-assisted depolymerization. The Fe-Al/TiO2 bifunctional catalyst exhibited superior biomass conversion, yielding more aliphatic hydrocarbons. Gas chromatography-mass spectrometry (GC-MS) revealed how catalysts influenced product distributions, increasing monoaromatic and aliphatic compounds and reducing oxygenated entities. Elemental analysis confirmed higher carbon content, lower oxygen levels, and improved higher heating values (HHVs) in catalyzed bio-oils, indicating enhanced fuel quality.
Citation - Scopus: 1
Hydrothermal Liquefaction of Sinapis Arvensis Biomass Using TiO2-Supported Metal Catalysts: A Study on Bio-Oil Yield and Composition
(Elsevier, 2026) Durak, Halil; Genel, Salih; Genel, Yasar
The development of catalytic systems for hydrothermal liquefaction (HTL) is crucial for transforming lignocellulosic biomass into biofuels with high energy density. This research investigates the HTL process of Sinapis arvensis biomass using TiO2-supported catalysts, specifically Fe, Al, and Fe-Al, at temperatures from 275-325 degrees C. The catalysts were synthesized through incipient wetness impregnation and characterized using techniques like X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), and inductively coupled plasma optical emission spectrometry (ICP-OES) to evaluate element distribution and surface chemistry. Findings show that the Al/TiO2 catalyst boosted lighter bio-oil production via acid-catalyzed dehydration and decarboxylation, while the Fe/TiO2 catalyst favored heavier oils through redox-assisted depolymerization. The Fe-Al/TiO2 bifunctional catalyst exhibited superior biomass conversion, yielding more aliphatic hydrocarbons. Gas chromatography-mass spectrometry (GC-MS) revealed how catalysts influenced product distributions, increasing monoaromatic and aliphatic compounds and reducing oxygenated entities. Elemental analysis confirmed higher carbon content, lower oxygen levels, and improved higher heating values (HHVs) in catalyzed bio-oils, indicating enhanced fuel quality.
Citation - WoS: 7
Citation - Scopus: 9
Input contract testing of graphical user interfaces
(World Scientific Publ Co Pte Ltd, 2016) Tuglular, Tugkan; Belli, Fevzi; Linschulte, Michael; Tuğlular, Tuğkan; Bilgisayar Mühendisliği Bölümü
User inputs are critical for the security, safety, and reliability of software systems. This paper proposes a new concept called user input contracts, which is an integral part of a design-by-contract supplemented development process, and a model-based testing approach to detect violations of user input contracts. The approach generates test cases from an input contract integrated with graph-based model of user interface specification and applies them to the system under consideration. The paper presents a proof-of-concept tool that has been developed and used to validate the approach by experiments. The experiments are conducted on a web-based system for marketing tourist services to analyze input robustness of system under consideration with respect to user input contracts.
Mixed Hydrogenetic-Hydrothermal Genesis of Quaternary Ferromanganese Nodules in a Tectonically Active Lacustrine Basin, Eastern Türkiye
(Pergamon-Elsevier Science Ltd, 2025) Uner, Tijen
This study presents a detailed investigation of the mineralogical, geochemical, and rare earth element (REE) characteristics of ferromanganese nodules found within Quaternary lacustrine sediments in the Agri region of Eastern Anatolia, T & uuml;rkiye. These nodules, primarily composed of goethite and manganite with minor quartz, exhibit botryoidal and colloform textures typical of low-temperature diagenetic environments. Raman and XRD analyses identified significant iron and manganese mineral phases, while SEM-EDX revealed trace amounts of Co, Ni, and Zn associated with these phases. Chondrite-normalized REE patterns demonstrate light REE enrichment, a weak negative europium anomaly (EuN/Eu* = 0.69-0.84), and variable cerium anomalies (CeN/Ce* ranging from 0.74 to 1.95, corresponding to both weak negative and positive Ce anomalies), indicating a mixed hydrogenous and hydrothermal origin under fluctuating redox conditions. These geochemical signatures, together with sedimentological evidence, suggest formation within a restricted lacustrine environment characterized by episodic anoxia and limited detrital input. The results contribute to a broader understanding of Fe-Mn mineralization in continental settings and underscore the influence of volcanic and tectonic processes on nodule genesis.
Mixed Hydrogenetic-Hydrothermal Genesis of Quaternary Ferromanganese Nodules in a Tectonically Active Lacustrine Basin, Eastern Türkiye
(Pergamon-Elsevier Science Ltd, 2025) Uner, Tijen
This study presents a detailed investigation of the mineralogical, geochemical, and rare earth element (REE) characteristics of ferromanganese nodules found within Quaternary lacustrine sediments in the Agri region of Eastern Anatolia, T & uuml;rkiye. These nodules, primarily composed of goethite and manganite with minor quartz, exhibit botryoidal and colloform textures typical of low-temperature diagenetic environments. Raman and XRD analyses identified significant iron and manganese mineral phases, while SEM-EDX revealed trace amounts of Co, Ni, and Zn associated with these phases. Chondrite-normalized REE patterns demonstrate light REE enrichment, a weak negative europium anomaly (EuN/Eu* = 0.69-0.84), and variable cerium anomalies (CeN/Ce* ranging from 0.74 to 1.95, corresponding to both weak negative and positive Ce anomalies), indicating a mixed hydrogenous and hydrothermal origin under fluctuating redox conditions. These geochemical signatures, together with sedimentological evidence, suggest formation within a restricted lacustrine environment characterized by episodic anoxia and limited detrital input. The results contribute to a broader understanding of Fe-Mn mineralization in continental settings and underscore the influence of volcanic and tectonic processes on nodule genesis.
Multimodal Prediction of Pathological Complete Response in Esophageal Cancer Using Automated Machine Learning and Variational Autoencoder-Based Synthetic Data Augmentation
(Amer Assoc Cancer Research, 2025) Dincer, Sefika; Tugrul, Taylan; Kara, Mahmut; Aldemir, Mehmet Naci
Multimodal Prediction of Pathological Complete Response in Esophageal Cancer Using Automated Machine Learning and Variational Autoencoder-Based Synthetic Data Augmentation
(Amer Assoc Cancer Research, 2025) Dincer, Sefika; Tugrul, Taylan; Kara, Mahmut; Aldemir, Mehmet Naci
Citation - WoS: 17
Citation - Scopus: 30
A Performance and profit oriented data replication strategy for cloud systems
(Ieee, 2016) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Bora, Sebnem; Ayav, Tolga; Bilgisayar Mühendisliği Bölümü
In today's world, tenants of cloud systems expect timely responses to queries that process ever-increasing sizes of data. However, most cloud providers offer their services without any performance guarantees to their tenants. In this paper we propose a data replication strategy that aims to satisfy performance guarantees for the tenant while ensuring profitability of the cloud provider. Our strategy estimates the response time of the queries, as well as the expenditures that affect the profitability of the cloud provider. The decision of whether to perform replication is determined by the fulfillment of these two criteria. Validity of the proposed strategy is provided by means of a simulation study.
Synthesis and Characterisation of Pd/MIL68(Al) Nanoparticles for High Performance Catalytic Reduction of 4-Nitrophenol
(Springer, 2025) Ruzgar, Adem
The discharge of 4-nitrophenol, one of the most significant, widespread, and hazardous organic pollutants found in industrial wastewater, into clean water resources without undergoing adequate and necessary treatment/conversion processes has become a multidimensional issue that threatens all aquatic life. In this study, the reduction of 4-nitrophenol to 4-aminophenol using an efficient, environmentally friendly, and sustainable method was targeted. For this purpose, Pd/MIL68(Al) catalyst was prepared with 2% metal loading using a simple and conventional wet impregnation method. MIL68(Al), an MOF recently attracting attention due to its superior properties, was synthesised using an efficient and environmentally friendly method as support material in the first step of nanocatalyst synthesis. The prepared Pd/MIL68(Al) catalyst was tested in the reaction of the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 by considering different parameters. In the study where the structure and surface morphology of the Pd/MIL68(Al) catalyst were elucidated using characterisation techniques such as ICP-OES, XRD, SEM, SEM/EDX, TEM, FTIR and XPS, it was determined that Pd(0) nanoparticles were well dispersed on the MIL68(Al) support, with an average particle size of 3.25 +/- 0.22 nm. As a result of the interpretation of the data obtained from the study, the TOFinitial value for 4-NP was determined as 43.42 min-1. In the studies carried out to determine the reusability rate of Pd/MIL68(Al) nanocatalyst, it was determined that Pd/MIL68(Al) nanocatalyst exhibited excellent catalytic efficiency and stability (92%) even after five catalytic cycles. Both the simple preparation process, catalytic efficiency, and high reusability rate of the Pd/MIL68(Al) nanocatalyst are the grounds for the evaluation of Pd/MIL68(Al) nanocatalyst as an important alternative for the reduction of 4-nitrophenol and wastewater treatment.
Synthesis and Characterisation of Pd/MIL68(Al) Nanoparticles for High Performance Catalytic Reduction of 4-Nitrophenol
(Springer, 2025) Ruzgar, Adem
The discharge of 4-nitrophenol, one of the most significant, widespread, and hazardous organic pollutants found in industrial wastewater, into clean water resources without undergoing adequate and necessary treatment/conversion processes has become a multidimensional issue that threatens all aquatic life. In this study, the reduction of 4-nitrophenol to 4-aminophenol using an efficient, environmentally friendly, and sustainable method was targeted. For this purpose, Pd/MIL68(Al) catalyst was prepared with 2% metal loading using a simple and conventional wet impregnation method. MIL68(Al), an MOF recently attracting attention due to its superior properties, was synthesised using an efficient and environmentally friendly method as support material in the first step of nanocatalyst synthesis. The prepared Pd/MIL68(Al) catalyst was tested in the reaction of the reduction of 4-nitrophenol to 4-aminophenol in the presence of NaBH4 by considering different parameters. In the study where the structure and surface morphology of the Pd/MIL68(Al) catalyst were elucidated using characterisation techniques such as ICP-OES, XRD, SEM, SEM/EDX, TEM, FTIR and XPS, it was determined that Pd(0) nanoparticles were well dispersed on the MIL68(Al) support, with an average particle size of 3.25 +/- 0.22 nm. As a result of the interpretation of the data obtained from the study, the TOFinitial value for 4-NP was determined as 43.42 min-1. In the studies carried out to determine the reusability rate of Pd/MIL68(Al) nanocatalyst, it was determined that Pd/MIL68(Al) nanocatalyst exhibited excellent catalytic efficiency and stability (92%) even after five catalytic cycles. Both the simple preparation process, catalytic efficiency, and high reusability rate of the Pd/MIL68(Al) nanocatalyst are the grounds for the evaluation of Pd/MIL68(Al) nanocatalyst as an important alternative for the reduction of 4-nitrophenol and wastewater treatment.
Why Disadvantaged Primary School Students in Rural Areas Have Lower Reading Skills? A Critical Assessment
(Routledge Journals, Taylor & Francis Ltd, 2025) Kiziltas, Yusuf; Kultas, Emrah
Inequalities between T & uuml;rkiye's geographical regions are significant. It is an important fact that students continuing their education in rural areas in eastern T & uuml;rkiye face many challenges compared to their peers in urban centers. The geography of rural areas can hurt students in several ways, particularly in terms of reading skills. The low reading skills of students in rural areas have been a serious problem in eastern T & uuml;rkiye for many years. National and international exam results also show that reading skills are lower in rural areas. In this study, the reasons for the low reading skills of primary school students in rural areas were critically examined through a literature review. The discussions include approaches such as the Matthew effect, spatial justice theory, and faucet theory. According to critical evaluations, the reasons for the low reading skills of disadvantaged primary school students in rural areas in eastern T & uuml;rkiye are pretty diverse. The socioeconomic levels of families, inequalities in opportunities and resources, school closures, negative factors related to location and geography, linguistic differences, problems with teaching materials, temporary teaching arrangements, and low levels of parental involvement are at the forefront.
Why Disadvantaged Primary School Students in Rural Areas Have Lower Reading Skills? A Critical Assessment
(Routledge Journals, Taylor & Francis Ltd, 2025) Kiziltas, Yusuf; Kultas, Emrah
Inequalities between T & uuml;rkiye's geographical regions are significant. It is an important fact that students continuing their education in rural areas in eastern T & uuml;rkiye face many challenges compared to their peers in urban centers. The geography of rural areas can hurt students in several ways, particularly in terms of reading skills. The low reading skills of students in rural areas have been a serious problem in eastern T & uuml;rkiye for many years. National and international exam results also show that reading skills are lower in rural areas. In this study, the reasons for the low reading skills of primary school students in rural areas were critically examined through a literature review. The discussions include approaches such as the Matthew effect, spatial justice theory, and faucet theory. According to critical evaluations, the reasons for the low reading skills of disadvantaged primary school students in rural areas in eastern T & uuml;rkiye are pretty diverse. The socioeconomic levels of families, inequalities in opportunities and resources, school closures, negative factors related to location and geography, linguistic differences, problems with teaching materials, temporary teaching arrangements, and low levels of parental involvement are at the forefront.

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