Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Optimizing Inhibitor Injection in Geothermal Wells With Electrical Submersible Pump(Elsevier Ltd, 2025) Aydin, H.; Tezel, S.I.; Erol, S.Electrical submersible pump (ESP) is a reliable artificial lift method to extend productive lifespan of geothermal wells. In the geothermal industry a common practice involves installing ESPs below the well's flashing depth. This placement approach aims to mitigate the risk of mineral precipitation, which can occur when hot geothermal fluids transition to a two-phase state (liquid and vapor) as pressure decreases. Positioning the pump below the flashing depth also prevents pump's underloading and gas cavitation. The inhibitor injection line usually integrated around the ESP string and installed downstream of the ESP motor. However, this standard practice introduces a challenge regarding inhibitor performance. While this placement ensures effective distribution of inhibitors throughout the production flow, the extended travel time from the surface to the point of application at the ESP can diminish inhibitor effectiveness due to continuous exposure to high temperatures throughout the wellbore. This study proposes relocating the inhibitor injection point within the production tubing closer to the flashing depth. This reduces inhibitor travel time from 108 min to 48 min and has the potential to significantly improve inhibitor effectiveness. Consequently, the implementation of capillary tubing is anticipated to yield annual cost savings per wellbore of approximately USD 10,000, coupled with the mitigation of mineral deposits within the studied well equipped with ESP. To evaluate this approach, a wellbore simulation tool and PHREEQC were employed to dynamically model the pressure and temperature profiles alongside the geochemical evolution of the produced fluids in the wellbore. This modeling approach offers significant value by potentially enabling the optimization of inhibitor usage and reducing the length of required inhibitor injection line. © 2024 Elsevier LtdConference Object Optimizing Integrated Shading Device and Light Shelf for Daylight Performance and Visual Comfort in Architecture Studio(Institute of Electrical and Electronics Engineers Inc., 2024) Avci, P.; Ekici, B.; Kazanasmaz, Z.T.To provide a sustainable interior, it is essential to consider visual comfort and energy efficiency for the occupants' well-being. Daylight is crucial in providing visual comfort while proposing energy-efficient design alternatives. Using daylight as a primary source is one of the most crucial strategies. However, controlling daylight for unwanted situations such as discomfort glare is important. There have been several research studies on daylighting, visual comfort, and shading techniques. Shading devices are façade configurations to control daylight, while light shelves distribute daylight evenly through the space. There are two types of classifications for shading devices: adaptive ones and non-adaptive ones. Numerous research studies have been conducted on daylighting, energy consumption, occupancy performance, and shading systems. Shading technologies, whether adaptive or not, provide benefits and drawbacks. Even though optimizing them is one way to design non-adaptive shading devices, they require minimal maintenance. This study aims to integrate adaptive shading devices and light shelves for university campus buildings to provide lighting design strategies. The aim is to create a study environment that promotes well-being and academic achievement. To pursue this study, three optimization algorithms were run to find the nearly optimal solution. The goal was to both maximize Daylight Autonomy and uniformity values. Results showed that HypE and SPEA2 results discovered near-optimal DA above 75% and uniformity between 0.6 and 0.7. © 2024 IEEE.Article Trna Wobble Base Modifications and Boric Acid Resistance in Yeast: Boron-Resistant Deletion Mutants Induce the General Amino Acid Control Mechanism and Activate Boron Efflux(NLM (Medline), 2020) Uluisik, I.; С Karakaya, H.; Koc, A.Boric acid is essential for plants and has many vital roles in animals and microorganisms. However, its high doses are toxic to all organisms. We previously screened yeast deletion collections to identify boric acid-resistant and susceptible mutants to identify genes that play a role in boron tolerance. Here, we analyzed boron resistant mutants (elplΔ, elp3Δ, elp6Δ, ncs2Δ, ncs6Δ and ktil2Δ) for their abilities to modulate the general amino acid control system (GAAC) and to induce boron efflux pump ATR1. The mutants analyzed in this study lack the genes that play roles in tRNA Wobble base modifications. We found that all of the boron resistant mutants activated Gcn4-dependent reporter gene activity and increased the transcript level of the ATR1 gene. Additionally, boron resistant cells accumulated less boric acid in their cytoplasm compared to the wild type cells upon boron exposure. Thus, our findings suggested that loss of wobble base modifications in tRNA leads to GAAC activation and ATR1 induction, which in turn reduced intracellular boron levels and caused boron resistance.Article Citation - WoS: 1Citation - Scopus: 1Completeness of Energy Eigenfunctions for the Reflectionless Potential in Quantum Mechanics(Aip Publishing, 2024) Erman, Fatih; Turgut, O. TeomanThere are a few exactly solvable potentials in quantum mechanics for which the completeness relation of the energy eigenstates can be explicitly verified. In this article, we give an elementary proof that the set of bound (discrete) states together with the scattering (continuum) states of the reflectionless potential form a complete set. We also review a direct and elegant derivation of the energy eigenstates with proper normalization by introducing an analog of the creation and annihilation operators of the harmonic oscillator problem. We further show that, in the case of a single bound state, the corresponding wave function can be found from the knowledge of continuum eigenstates of the system. Finally, completeness is shown by using the even/odd parity eigenstates of the Hamiltonian, which provides another explicit demonstration of a fundamental property of quantum mechanical Hamiltonians.Article Citation - WoS: 3Citation - Scopus: 3Two Decades of Research on Roma in Türkiye: Socioeconomic Exclusion, Identity, and State Policies(Liverpool Univ Press, 2024) Celik, Faika; Uştuk, Ozan; Ustuk, OzanThe scholarly investigation of Roma communities in Turkiye has intensified since the 2000s, largely driven by Turkiye's EU accession candidacy and subsequent adaptation process. This alignment, along with internal developments, prompted governments to prioritize Roma issues, implement projects, and issue action plans. The Roma Civil Society Movement in the 1990s further highlighted Roma challenges, resulting in a diverse body of literature. This study critically examines academic literature to map prevailing trends and thematic foci. Key areas of scholarly engagement include the various dimensions of socio-economic exclusion faced by Roma in education, employment, housing, and health. Additionally, scholars analyze how Roma negotiate and resist pejorative representations, construct their identities, and organize to address contemporary challenges. State policies affecting Roma, from past to present, also receive considerable attention. By critically engaging with this scholarship, the present study highlights significant progress and ongoing challenges in Romani Studies in Turkiye, offering insights into future research directions.Article Citation - WoS: 7Citation - Scopus: 7Bond-Based Peridynamic Fatigue Analysis of Ductile Materials With Neuber's Plasticity Correction(Springer, 2024) Altay, Ugur; Dorduncu, Mehmet; Kadioglu, Suat; Madenci, ErdoganThis study introduces an approach for performing bond-based (BB) peridynamic (PD) fatigue analysis of ductile materials. Existing BB PD fatigue models do not account for the effect of plastic deformation. The current approach addresses this by incorporating Neuber's plasticity correction concept into the fatigue model. Neuber's correction adjusts the stress and strain predictions of the PD elastic solution to account for local plastic deformation around crack tips. The PD fatigue simulations demonstrate the effectiveness of this method and improvements in fatigue life predictions by considering local plasticity effects. The numerical results first examine the response of a ductile plate without a crack under quasi-static monotonic loading. Subsequently, specimens exhibiting Mode I and mixed-mode crack propagation paths due to cyclic loading are analyzed. The PD predictions accurately capture the test data. Additionally, the model specifically investigates the effect of a stop hole on fatigue life.Article Citation - WoS: 4Citation - Scopus: 5Diffusion-Based Data Augmentation Methodology for Improved Performance in Ocular Disease Diagnosis Using Retinography Images(Springer Heidelberg, 2024) Aktas, Burak; Ates, Doga Deniz; Duzyel, Okan; Gumus, AbdurrahmanDeep learning models, integral components of contemporary technological landscapes, exhibit enhanced learning capabilities with larger datasets. Traditional data augmentation techniques, while effective in generating new data, have limitations, especially in fields like ocular disease diagnosis. In response, alternative augmentation approaches, including the utilization of generative AI, have emerged. In our study, we employed a diffusion-based model (Stable Diffusion) to synthesize data by faithfully recreating crucial vascular structures in the retina, vital for detecting eye diseases by using the Ocular Disease Intelligent Recognition dataset. Our goal was to augment retinography images for ocular disease diagnosis using diffusion-based models, optimizing the outputs of the fine-tuned Stable Diffusion model, and ensuring the generated data closely resembles real-world scenarios. This strategic approach resulted in improved performance in classification models and augmentation outperformed traditional methods, exhibiting high precision rates ranging from 85% to 76.2% and recall values of 86%, and 75% for 5 classes. Beyond performance enhancement, we demonstrated that the inclusion of synthetic data, coupled with data reduction using the t-SNE method, effectively addressed dataset imbalance. As a result of synthetic data addition, notable increases of 3.4% in the precision metric and 12.8% in the recall metric were observed in the 7-class case. Strategically synthesizing data addressed underrepresented classes, creating a balanced dataset for comprehensive model learning. Surpassing performance improvements, this approach underscores synthetic data's ability to overcome the limitations of traditional methods, particularly in sensitive medical domains like ocular disease diagnosis, ensuring accurate classification. The codes of the study will be shared on GitHub in a way that benefits everyone interested: https://github.com/miralab-ai/generative-data-augmentation.Article Citation - WoS: 4Citation - Scopus: 4Vo<sub>2</Sub>-based Dynamic Coding Metamaterials for Terahertz Wavefront Engineering(Springer, 2025) Akyurek, Bora; Noori, Aileen; Demirhan, Yasemin; Ozyuzer, Lutfi; Guven, Kaan; Altan, Hakan; Aygun, GulnurDigital coding metasurfaces (DCMS) offer a promising alternative to conventional metasurface designs for achieving common functionalities by controlling the phase of reflected or transmitted electromagnetic waves. Their simple unit cell designs allow for scalability across the THz spectrum and facilitate large-area fabrication. The true potential of DCMS lies in dynamical coding, which enables real-time reconfigurability through a tuning and/or switching mechanism. In this study, metasurfaces that achieve 1-bit dynamic coding of unit cells via thermally induced metal-insulator transition of VO2 layers are designed and fabricated. We investigate experimentally the beam splitting functionality at certain frequencies in the 0.50-0.75 THz range reflected from the stripe- and checkerboard patterned metasurface samples, and demonstrate the switching of this functionality under thermal illumination.Article Citation - WoS: 5Citation - Scopus: 5Multiorgan-On for Cancer Drug Pharmacokinetics-Pharmacodynamics (pk-Pd) Modeling and Simulations(Springer/plenum Publishers, 2025) Mohammed, Abdurehman Eshete; Kurucaovali, Filiz; Okvur, Devrim PesenCancer is one of the most common and fatal diseases worldwide and kills millions of people every year. Cancer drug resistance, lack of efficacy, and safety are significant problems in cancer patients. A multiorgan-on-a-chip (MOC) device consisting of breast and liver compartments was designed with AutoCAD software. The MOC molds were printed by a Formlabs Form 2 3D printer. MDA-MB-231, HepG2, and MCF-10 A cells were used for the MOC experiments. The cell lines were cultured at 37 degrees C with 5% CO2, and cell viability was assessed via Alamar blue dye to generate pharmacodynamics (PD) data. Drug concentrations from the cell culture media were analyzed via Agilent 1260 Infinity II HPLC with a Waters Symmetry C18 column and used to generate pharmacokinetics (PK) data. The PK and PD data were modeled and simulated by Monolix and Simulix software, respectively. The safety and efficacy of drug dosing regimens were compared, and the best dosing regimens were selected. This research designed and fabricated a unique MOC consisting of liver and breast compartments that overcomes the need for sealing or assembling. It was used for PK-PD modeling and simulations, and its functionality was proven experimentally. The new MOC will be helpful in preclinical trials to evaluate the efficacy and safety of drugs.Article Citation - WoS: 7Citation - Scopus: 7Development of a Dopamine-Based Surface Modification Technique To Enhance Protein Fouling Resistance in Commercial Ultrafiltration Membranes(Elsevier, 2025) Onuk, Ecem; Gungormus, Elif; Cihanoglu, Aydin; Altinkaya, Sacide AlsoyThis study introduces a new method for modifying ultrafiltration membranes using dopamine polymerization to overcome issues such as prolonged polymerization times, potential pore narrowing, and insufficient formation of hydrophilic groups. The technique involves continuously supplying oxygen (O2) gas from the porous backside of the membrane while simultaneously applying an aqueous dopamine solution to the active top surface. TGA and XPS analyses revealed that 10 kDa commercial polysulfone (PSF) membranes coated with O2 backflow contained more dopamine than those modified using the classical method. Additionally, changes in contact angle and zeta potential values were more pronounced with the O2 backflow method. Dopamine coating for 10 and 20 min improved the pure water permeance of the PSF membrane, whereas a 40-min coating decreased it. Notably, the reduction in permeance was 2.5 times less with the O2 backflow method than with the classical method. The classical dopamine coating method did not enhance the PSF membrane's resistance to fouling during whey filtration; in fact, 20 and 40-min coatings caused more significant flux declines compared to the unmodified membrane. Conversely, 10 and 20 min of PDA coating under O2 backflow improved fouling resistance, though this benefit disappeared with a 40-min coating.