WoS İndeksli Yayınlar Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394
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Article Exergy-Based Evaluation of High-CO2 Biogas/Diesel RCCI Combustion Heat Flow for Enhanced Mixture Distribution, Power Output, and Fuel-Energy Performance(Pergamon-Elsevier Science Ltd, 2026) Dalha, Ibrahim B.; El-Adawy, Mohammed; Wong, Nur Leena W. S.; Man, Hafsalina C.; Said, Mior A.; Koca, Kemal; Abdulsalam, MuhammedUtilising high-CO2 biogas in compression-ignition engines poses significant challenges due to poor mixture reactivity, inefficient combustion, and increased energy degradation. This work addresses these difficulties by conducting experimental research on a port-injection at the valve reactivity-controlled compression ignition (PIVE-RCCI) strategy. This study addresses these concerns by conducting experiments on a PIVE-RCCI technique to improve mixture distribution and combustion efficiency in biogas-diesel engines. The engine was modified to provide biogas through the inlet valve, allowing for controlled variations of biogas injection pressure (BIP: 1-4 bar) and port swirl ratio (PSR: 0-80%) at 1600 rpm and 4.9-5.7 bar IMEP. Energy and exergy analyses were used to determine the effect of intake flow dynamics on temperature uniformity, heat transfer, and power generation during combustion. The results reveal that normal airflow conditions minimise accounted heat loss, indicating higher thermal efficiency (ITE) and increased output power across all BIPs. In contrast, introducing a strong intake swirl dramatically improves combustion performance. The 80% PSR configuration resulted in the lowest exergy destruction and the maximum energy recovery potential, with an ITE of 26.54% at 4 bar BIP. Increasing BIP increased power output, whereas the optimal combustion work was found at 1 bar BIP and 40% PSR. The optimal working conditions were 1 bar BIP, 80% PSR, and 5.45 bar IMEP, which resulted in 26.00% exergy destruction, 39.38% destruction-to-released exergy ratio, 86.00% exergy-energy ratio of heat transfer, and 63.78% exhaust exergy-energy ratio. This work's novelty lies in integrating biogas injection, intake swirl control, and exergy-based evaluation to measure mixture distribution and energy recovery in high-COQ biogas RCCI combustion. The findings offer useful operational guidance for increasing energy efficiency and advancing the commercialization of renewable gaseous fuels in RCCI engines. As a result, operating the engine at half load, 80% PSR, and atmospheric air pressure (1 bar) conditions significantly enhanced the combustion efficiency and energy utilisation.Article Citation - WoS: 15Citation - Scopus: 17Investigation of the Performance and Properties of ZnO/GO Double-Layer Supercapacitor(Pergamon-Elsevier Science Ltd, 2024-08) Buyukkurkcu, Handan; Durmus, Ali; Colak, Hakan; Kurban, Rifat; Sahmetlioglu, Ertugrul; Karakose, ErcanComposite electrode material was formed by mixing reduced graphene oxide (rGO) and zinc oxide (ZnO) compound, using the Hummers and green synthesis methods, respectively. Of rGO powder, 10 g was mixed with 10%, 20% and 30% ZnO, and composite electrodes were obtained by using 10% binder. The energy storage performance and structural characteristics of the supercapacitor were evaluated by analyzing the capacitance values of the synthesized electrodes. The structural characterization of ZnO/rGO composites was performed using X-ray diffraction and field-emission scanning electron microscopy. The electrochemical properties of the ZnO/GO electrodes were analyzed by cyclic voltammetry, electrochemical impedance and galvanostatic charge -discharge tests. The specific capacitance value of electrodes increased as zinc content increased in the ZnO/ rGO composite material used to produce electrodes. The maximum specific capacitance values were measured at 5 mV/s scanning rate as 194.23 (rGO), 366.81 (10% ZnO), 383.18 (20% ZnO) and 410.48 F/g (30% ZnO). In conclusion, the use of composite material formed by the combination of ZnO nanoparticles obtained by green synthesis method from orange peel and graphene oxide increased the electrochemical efficiency of the supercapacitor.Article Citation - WoS: 10Citation - Scopus: 11Effect of Bio-Mimicked Surface Texturing on the Shear Strength of Additively Manufactured Metal Single-Lap Joints: An Innovative Approach(Pergamon-Elsevier Science Ltd, 2025-06) Atahan, M. Gokhan; Maskery, Ian; Ashcroft, Ian; Apalak, M. Kemal; Pappas, AthanasiosIn this paper, we investigate the mechanical performance of metal single-lap joints featuring bio-mimicking surface textures. The inspiration for the surface textures was the foot and toe of the gecko, a creature whose ability to climb smooth shear surfaces is attributed to the mesoand micro-structures of its feet. Three surface textures were investigated: a hexagonal texture based on the central region of the foot, a lamellae-like texture based on the toe, and a mixed texture of both. Metal adherends with these textures were produced using the laser powder bed fusion (LPBF) additive manufacturing method. Finite element analysis was performed to examine the influence of surface texture on stress distribution in the adhesive layer, while mechanical testing was used to determine joint strength and failure mode. Compared to the as- printed surface texture, bio-mimicking surface textures improved the wettability of the bonding surfaces, and significantly improved the lap shear strength of the joints. Mechanical interlocking due to surface texture was more effective than the increase in bonding surface area in enhancing joint strength. The bio-mimicking textures improved the damage tolerance capacity of the joints by reducing local stress concentrations at the overlap edges of the adhesive layer and ensured that the adhesive failure type was mixed mode due to the mechanical interlocking effect. The presented novel bio-mimicked surface texture method offers promising results for both industrial applications and scientific studies.Article Citation - WoS: 12Citation - Scopus: 12Edge Dislocation Depinning From Hydrogen Atmosphere in Α-Iron(Pergamon-Elsevier Science Ltd, 2024-07) Kapci, Mehmet Fazil; Yu, Ping; Marian, Jaime; Liu, Guisen; Shen, Yao; Li, Yang; Bal, BurakUnderstanding the dislocation motion in hydrogen atmosphere is essential for revealing the hydrogen-related degradation in metallic materials. Atomic simulations were adopted to investigate the interaction between dislocations and hydrogen atoms, where the realistic hydrogen distribution in the vicinity of the dislocation core was emulated from the Grand Canonical Monte Carlo computations. The depinning of edge dislocations in alpha-Fe at different temperatures and hydrogen concentrations was then studied using Molecular Dynamics simulations. The results revealed that an increase in bulk hydrogen concentration increases the flow stress due to the pinning effect of solute hydrogen. The depinning stress was found to decrease due to the thermal activation of the edge dislocation at higher temperatures. In addition, prediction of the obtained results was performed by an elastic model that can correlate the bulk hydrogen concentration to depinning stress.Article Development and Radiation Test of a Secondary Emission Ionization Calorimetry Module(Pergamon-Elsevier Science Ltd, 2025-06) Paran, Nejdet; Tiras, Emrah; Tekgun, Burak; Abubakar, SalehThe demand for precise, robust, and reliable radiation-resistant particle detectors and ionization calorimeters intensifies due to the escalating luminosity and unprecedented radiation conditions at particle colliders and accelerators. Secondary Emission (SE) Ionization Calorimetry is a novel technology designed to measure the energy of electromagnetic and hadronic particles, particularly in extreme radiation conditions. In this study, we have tested and investigated the development and radiation tests of the novel SE modules. The modules were developed by modifying the conventional Hamamatsu single-anode R7761 Photomultiplier Tubes (PMTs). Three different voltage conditions for the same module were created and the new modules were tested using cosmic and gamma radiation sources, Co-60. The results show that all three modes have good sensitivity to electromagnetic showers, and they are suitable for harsh radiation environments. This study also indicates that the SE module is a promising technology shedding light on future radiation-resistant nuclear and high-energy detectors. Here, we discuss the technical design, test characteristics, and cosmic and particle interaction results of the newly developed SE modules.Article Citation - WoS: 17Citation - Scopus: 20Comparative Study on Bending Behavior and Damage Analysis of 3D-Printed Sandwich Core Designs With Bio-Inspired Reinforcements(Pergamon-Elsevier Science Ltd, 2024-09) Atahan, M. Gokhan; Erikli, Merve; Ozipek, Enes; Ozgun, FulyaIn this study, novel sandwich core designs with bio-inspired reinforcements were proposed and their bending behaviors were comparatively examined. The geometrical shapes of alligator osteoderm and chambered nautilus shell were utilized as bio-inspired reinforcements for sandwich core structures. Sandwich core structures were produced through the additive manufacturing method. Experimental tests and finite element analysis were performed to determine the bending performances of the proposed sandwich core structures. The loadcarrying capacity, deformation ability, damage-tolerant capability, energy absorption, and damage mechanisms of the proposed sandwich core structures were comparatively investigated through experimental and numerical methods. The orthotropic material model and Hashin's damage criterion were used in the numerical model of 3D-printed sandwich core structures to consider the effect of the filament raster orientation on the elastic and damage behavior of the sandwich core structures. Compared to the classical honeycomb sandwich core structure, while bio-inspired reinforcements improved the load-carrying capacity and damage-tolerant capability of sandwich core structures, they reduced the energy absorption ability of sandwich core structures due to reducing the vertical deformation ability of sandwich core structures. Bio-inspired reinforcements significantly affected the stress distribution and damage behavior of the sandwich core structures. They reduced von Mises stress level at the outer cell edges of the sandwich core structures and caused reinforcement damage instead of outer cell damage.Article Citation - WoS: 17Citation - Scopus: 18Comparative Analysis of Hybrid Geothermal-Solar Systems and Solar PV With Battery Storage: Site Suitability, Emissions, and Economic Performance(Pergamon-Elsevier Science Ltd, 2025-01) Fedakar, Halil Ibrahim; Dincer, Ali Ersin; Demir, AbdullahRenewable energy integration has become a critical focus in the global effort to reduce carbon emissions and diversify energy sources. In regions with distinct geographic features, such as Turkiye, combining different renewable technologies can offer enhanced energy security. This study investigates the site suitability and economic and environmental performance of hybrid geothermal-solar systems and solar PV systems with battery storage across the provinces of Osmaniye, Hatay, and Kilis, of Turkiye. Using the fuzzy-AHP method, site suitability is evaluated, addressing a key gap in comparing these systems' adaptability to varying geographic conditions. This study is the first to directly compare these two renewable energy technologies in terms of site suitability. The findings reveal significant differences in site suitability, with solar PV systems with battery storage demonstrating broader applicability across the region. The suitable sites (20-100 % suitability) cover 1260.82 km(2) for solar PV systems with battery storage and only 122.18 km(2) for hybrid geothermal-solar systems. In terms of environmental impact, hybrid geothermal-solar systems exhibit significantly lower carbon emissions, averaging 44.6 kg CO2/MWh, compared to 123.8 kg CO2/MWh for solar PV systems with battery storage. Economically, hybrid geothermal-solar systems also outperform with a lower levelized cost of electricity of $0.091 kWh versus $0.254 kWh for solar PV systems. These results highlight the environmental and economic advantages of hybrid geothermal-solar systems, while also emphasizing their limited scalability to regions with geothermal activity. Conversely, solar PV systems, despite their higher emissions and costs, offer greater flexibility and potential for widespread deployment.Article Citation - WoS: 5Citation - Scopus: 9Assembling a Justified List of Academic Words in Veterinary Medicine: The Veterinary Medicine Academic Word List (VMAWL)(Pergamon-Elsevier Science Ltd, 2024-04) Ozer, Mustafa; Akbas, ErdemThe assembly of corpus-based discipline-specific word lists for pedagogical purposes has recently been on the rise (e.g., Arndt, 2022; Fraser, 2007; O'Flynn, 2019; Yang, 2015). In order to cater to the needs of learners in veterinary medicine (VM) and for field-specific academic literacy, this paper analyses a reiteration of the Veterinary Medicine Corpus (ozer and Akbas, , 2023; hereafter the VMC), assembling a specified list of academic words used in published research articles (RAs) in VM. So far, VM has remained largely unexplored with the exception of Durrant's (2009) limited coverage of VM texts. The analysis was conducted using LancsBox 6.0, prompted to yield a list of PoS-tagged lemmas (Plemmas) sorted by frequency (Coxhead, 2000; Yang, 2015) and dispersion (Arndt, 2022). The most frequent 1,000 lemmas for each content word category were collated into a candidate list. We then manually eliminated proper nouns and GSL (West, 1953) words. The final list, the Veterinary Medicine Academic Word List (VMAWL), contains 835 PoStagged lemmas (P-lemmas), a reiteration of which was produced by adding the types in Bauer and Nation's (1993) taxonomy at the second level to test coverage. The VMAWL was profiled and validated against the four parent categories independently on AntWordProfiler (Anthony, 2022a) with analysis showing the VMAWL comprises 13.75 % of the VMC and diverges greatly from generic word lists like the AWL, NGSL, new-GSL, and AVL. The list can be used to develop teaching materials for EAP or ESP academic writing courses. (c) 2023 Elsevier Ltd. All rights reserved.Article Citation - WoS: 34Citation - Scopus: 35An Atomistic Study on the Help Mechanism of Hydrogen Embrittlement in Pure Metal Fe(Pergamon-Elsevier Science Ltd, 2024-02) Hasan, Md Shahrier; Kapci, Mehmet Fazil; Bal, Burak; Koyama, Motomichi; Bayat, Hadia; Xu, WenwuThe Hydrogen Enhanced Localized Plasticity (HELP) mechanism is one of the most important theories explaining Hydrogen Embrittlement in metallic materials. While much research has focused on hydrogen's impact on dislocation core structure and dislocation mobility, its effect on local dislocation density and plasticity remains less explored. This study examines both aspects using two distinct atomistic simulations: one for a single edge dislocation under shear and another for a bulk model under cyclic loading, both across varying hydrogen concentrations. We find that hydrogen stabilizes the edge dislocation and exhibits a dual impact on dislocation mobility. Specifically, mobility increases below a shear load of 900 MPa but progressively decreases above this threshold. Furthermore, dislocation accumulation is notably suppressed at around 1 % hydrogen concentration. These findings offer key insights for future research on Hydrogen Embrittlement, particularly in fatigue scenarios.Article Citation - WoS: 4Citation - Scopus: 4A Phenomenological Hydrogen Induced Edge Dislocation Mobility Law for Bcc Fe Obtained by Molecular Dynamics(Pergamon-Elsevier Science Ltd, 2024-10) Baltacioglu, Mehmet Furkan; Kapci, Mehmet Fazil; Schoen, J. Christian; Marian, Jaime; Bal, Burak; Schön, J. ChristianInvestigating the interaction between hydrogen and dislocations is essential for understanding the origin of hydrogen-related fractures, specifically hydrogen embrittlement (HE). This study investigates the effect of hydrogen on the mobility of 1/2<111>{110} and 1/2<111>{112} edge dislocations in body-centered cubic (BCC) iron (Fe). Specifically, molecular dynamics (MD) simulations are conducted at various stress levels and temperatures for hydrogen-free and hydrogen-containing lattices. The results show that hydrogen significantly reduces dislocation velocities due to the pinning effect. Based on the results of MD simulations, phenomenological mobility laws for both types of dislocations as a function of stress, temperature and hydrogen concentration are proposed. Current findings provide a comprehensive model for predicting dislocation behavior in hydrogencontaining BCC lattices, thus enhancing the understanding of HE. Additionally, the mobility laws can be utilized in dislocation dynamics simulations to investigate hydrogen-dislocation interactions on a larger scale, aiding in the design of HE-resilient materials for industrial applications.