Yazar "Baydir, Enver" seçeneğine göre listele

Listeleniyor 1 - 5 / 5
  • Küçük Resim Yok
    Öğe
    Effect of pre-anodizing, electrocoating processes and fatty acid chain length on morphology, roughness and durability of ZnO-coated superhydrophobic surfaces
    (Springer Heidelberg, 2022) Aras, Omur; Baydir, Enver; Akman, Bugra
    Anodizing process was applied for the first time in this study for pre-modification of the 1050 aluminum surface before the zinc electrodeposition to obtain superhydrophobic surface by modifying with palmitic, lauric and stearic acid for the comparison. The effect of the pre-anodizing process, the electrodeposition time and the acid chain length on the super-hydrophobicity and durability was investigated in detail to explain the relationships between the roughness, morphology and acid chain length. Anodized, electrocoated and modified surfaces were characterized by FTIR, XRD, SEM and topography analysis. The highest contact angles were 154 degrees, 157 degrees and 160 degrees for electrodeposition process modified with lauric, palmitic and stearic acid, respectively. Sandpaper abrasion, UV, pH and temperature tests showed that molecular length, pre-anodizing and coating time strongly related the durability and super-hydrophobicity of the coated surfaces. As a result, anodizing time has a great impact on the durability and contact angle compared to non-anodized plates thanks to the creating macro-roughness.
  • Küçük Resim Yok
    Öğe
    Machine learning modeling of ceramic beads: Impact of PVA and water on porosity and strength
    (Elsevier, 2025) Baydir, Enver; Sen, Hasan; Aras, Omuer
    In this study, ceramic beads with adjustable apparent porosity and compressive strength were successfully produced using the Na-alginate gelation method, with kaolin and zeolite as the raw materials. The effects of varying PVA and water ratios on apparent porosity, water absorption, and compressive strength were thoroughly examined. Zeolite exhibited a maximum apparent porosity of 33.93 %, while kaolin reached 55.06 %. Regarding compressive strength, zeolite showed superior performance with a value of 10.49 MPa, compared to 0.44 MPa for kaolin. Zeolite-based ceramic beads exhibited lower porosity but significantly higher compressive strength than kaolin-based beads, demonstrating enhanced mechanical properties. Characterization using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared (FT-IR) spectroscopy provided insights into the crystalline structure, morphology, and chemical composition of the beads. These techniques revealed detailed structural properties of the ceramic beads. To predict key properties such as apparent porosity (AP), water absorption (WA), and compressive strength (CS), machine learning models including XGBoost, Random Forest, Support Vector Regression (SVR), and Artificial Neural Networks (ANN) were employed. The performance of these models was assessed using R2, MAE (Mean Absolute Error), MSE (Mean Squared Error), and RMSE (Root Mean Squared Error) metrics. Among these models, SVR provided the most reliable predictions, while XGBoost also yielded competitive results. To improve interpretability, SHAP (Shapley Additive Explanations), LIME (Local Interpretable Model-agnostic Explanations), and Type II ANOVA (Analysis of Variance) were used. SHAP and Type II ANOVA identified 'Ceramic' as the most impactful variable, with LIME revealing its local effects, enhancing transparency in model decision-making.
  • Küçük Resim Yok
    Öğe
    Molecular Adsorption of Silane on Ge, Ga and Al-doped CNT Structures: A Density Functional Theory Study
    (Maik Nauka/Interperiodica/Springer, 2022) Baydir, Enver; Altun, Aycan; Fellah, M. Ferdi
    The adsorption of silane molecule on the pristine CNT structure and metal-doped (Ge, Ga and Al) CNT (4,0) structure were investigated by DFT (density functional theory). Adsorption enthalpy, energy, chemical potential, chemical hardness values and electronic properties of CNT structures were obtained and reported. All metal-doped CNT structures gave more negative adsorption energy values for silane adsorption compared to the pristine CNT structure. The adsorption enthalpy energy value for silane adsorption on Ga doped CNT was calculated as -31 kJ/mol. In other words, the Ga-doped CNT structure may be a suitable material for silane adsorption with high adsorption energy change as a negative value. It was also investigated whether metal-doped and pristine CNT structures act as sensors for silane. In this study, metal-doped CNT structures examined show high adsorption properties but not sensor properties.
  • Küçük Resim Yok
    Öğe
    Synergy of 3D, porous supports and surface alkalinity tendency in Cu/ZnO catalysts for methanol steam reforming
    (Pergamon-Elsevier Science Ltd, 2026) Baydir, Enver; Aras, Omur
    The growing recognition of hydrogen as a strategic energy carrier has increased the need for efficient lowtemperature processes. Methanol steam reforming (MSR) is promising due to its mild operating conditions. Packed-bed reactors are widely used; however, achieving high conversion and selectivity is difficult because of heat and mass transfer limitations and poor reactant-catalyst contact, often requiring higher temperatures or alternative designs. This work addresses these challenges by developing three-dimensional, porous supports with controlled Ca modification. Zeolite- and kaolin-based supports were prepared by wet granulation and modified with different Ca(OH)2 loadings. Moderate Ca addition promoted CaO formation and improved porosity, whereas excessive loading reduced it, impairing performance. Z-HP-15Ca@Cu/ZnO showed the best zeolite performance, while K-HP-10Ca@Cu/ZnO was optimal for kaolin. Statistical analysis confirmed higher conversion for zeolitebased catalysts. Overall, this strategy couples Ca-derived surface species with support porosity to achieve high MSR performance at low temperatures.
  • Küçük Resim Yok
    Öğe
    The role of CO adsorption and CuO formation on the catalyst deactivation during the long-term performance evaluation of methanol steam reforming process for hydrogen production: Comparison of sono-coprecipitation and spray pyrolysis method
    (Pergamon-Elsevier Science Ltd, 2022) Baydir, Enver; Aras, Omur
    In this study, microreactors were coated with catalysts synthesized by two different methods and hydrogen was produced by methanol steam reforming. The structure of the catalysts was characterized by XRD, SEM and EDS analyses in the synthesis, activation and after long-term evaluation stages. The effect of CO adsorption and the structural changes of catalysts on the product stream and conversion were investigated and compared in detail. As a result, it was observed that the catalyst prepared by sono-coprecipitation (SCC) was more active although lost its performance much faster. Considering the performance graphs, SEM/EDS analyses and XRD results, it was revealed that the main reason for the performance decrease of the SPC-reactor (spray pyrolysis coating) was the increase of CO adsorption on the surface. Also, the formation of CuO structures and CO adsorption in the SCC-reactor were responsible for the faster performance decrease.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.