Enerji Yönetimi Bölümü Koleksiyonu

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https://hdl.handle.net/20.500.12428/3894

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Tailoring the physical properties of ultrasonically spray pyrolyzed SnS thin films with silver doping
(Springer, 2025) Güneş, İbrahim; Sarıca, Emrah; Bilgin, Vildan; Küçükarslan, Ayşe
In this study, the effects of silver (Ag) doping on the structural, morphological, optical, and electrical properties of tin monosulfide (SnS) thin films were investigated. The films, undoped and doped with 3%, 6%, and 9% Ag, were deposited using the ultrasonic spray pyrolysis (USP) technique at a substrate temperature of 350 degrees C. X-ray diffraction (XRD) analysis confirmed a pi-SnS (cubic) structure with (400) preferred orientation for undoped and <= 6% Ag-doped films, while 9% doping induced amorphization due to severe lattice distortions. Morphological analyses revealed smooth, void-free surfaces, with average roughness increasing from 5.8 nm (undoped) to 19.6 nm (9% doping). Optical measurements showed that the band gap widened from 1.84 eV (undoped) to 2.47 eV (9% Ag-doped), and Urbach energy increased from 190 meV to 600 meV. Hall effect measurements confirmed p-type conductivity for all films. Resistivity ranged from 4.34 x 10(5) Omega cm to 9.48 x 10(5) Omega cm, carrier concentration varied between 2.7 x 10(12) cm(-3) and 5.6 x 10(12) cm(-3), while mobility decreased from 3.3 x 10(1) cm(2)/Vs to 2.0 x 10(1) cm(2)/Vs with increasing Ag doping. These findings demonstrate that Ag doping significantly influences the structural and optoelectronic behavior of SnS thin films, making them promising candidates for thin-film solar cells and optoelectronic applications.
Calculation Of The Damping Constant (FWHM), The Relaxation Time, And The Activation Energy As A Function Of Temperature For DmaCd(N3)3
(Elsevier B.V., 2021) Kurt, Arzu
The Raman frequencies of τ(CH3), υs(CNC), υ1(N3) and δ(CH3) modes, the IR frequencies of δ(NH2) and ρ(NH2) modes, and the corresponding FWHM values for these modes in DMACd(N3)3 were analyzed by using the experimental data from the literature for both ferroelastic and paraelastic phases. In these analyses, the Raman and the IR frequencies of these modes were associated with the order parameter calculated from the molecular field theory with regard to the structural phase transition (Tc=174 K) in DMACd(N3)3, the frequencies and the damping constants of τ(CH3), υs(CNC), υ1(N3), δ(CH3), δ(NH2), and ρ(NH2) modes as a function of temperature through the model of pseudospin (dynamic disorder of DMA+ cations and partially N3 anion), phonon coupling (PS) model, and the energy fluctuation (EF) model by analyzing the experimental data for the frequencies and FWHM of these modes in hybrid organic-inorganic perovskite. Moreover, the relaxation time and the activation energy were calculated for all these modes at various temperatures by using the damping constants (FWHM) for the PS and EF models studied in DMACd(N3)3. The results of the present research showed that the calculated Raman and IR frequencies with the damping constants of τ(CH3), υs(CNC), υ1(N3), δ(CH3), δ(NH2), and ρ(NH2) modes adequately accounted for the experimental data in DMACd(N3)3. The calculated activation energies for these modes were found to be acceptable compared to the values available in the literature and the kBTc values at the critical temperature. This method for calculating the frequencies (IR and Raman) and FWHM of these modes that were associated with the phase transitions could also be applied to some other hybrid organic-inorganic perovskites.
Testing the Wind Energy Data Based on Environmental Factors Predicted by Machine Learning with Analysis of Variance
(Mdpi, 2025) Atalan, Yasemin Ayaz; Atalan, Abdulkadir
This study proposes a two-stage methodology for predicting wind energy production using time, environmental, technical, and locational variables. In the first stage, machine learning algorithms, including random forest (RF), gradient boosting (GB), k-nearest neighbors (kNNs), linear regression (LR), and decision trees (Tree), were employed to estimate energy output. Among these, RF exhibited the best performance with the lowest error metrics (MSE: 0.003, RMSE: 0.053) and the highest R-2 value (0.988). In the second stage, analysis of variance (ANOVA) was conducted to evaluate the statistical relationships between independent variables and the predicted dependent variable, identifying wind speed (p < 0.001) and rotor speed (p < 0.001) as the most influential factors. Furthermore, RF and GB models produced predictions most closely aligned with actual data, achieving R-2 values of 88.83% and 89.30% in the ANOVA validation phase. Integrating RF and GB models with statistical validation highlighted the robustness of the methodology. These findings demonstrate the robustness of integrating machine learning models with statistical verification methods.
Numerical and Statistical Aerodynamic Performance Analysis of NACA0009 and NACA4415 Airfoils
(Gazi Univ, 2024) Evran, Savaş; Yıldır, Salih Zeki
In this numerical and statistical study, lift and drag coefficient performances of NACA-0009 and NACA-4415 airfoils were evaluated in accordance with various attack angle at constant velocity of wind. Lift and drag coefficients of airfoils was numerically determined by computational fluid dynamics code ANSYS FLUENT. Analysis design of numerical calculations was implemented using L16 orthogonal array based on Taguchi method. Angles of attack and airfoil types were considered as control factors. The optimum level and effect of each control factor on responses was statistically implemented using analyses of Signal-to-Noise ratio and variance. As a result of this study, maximum lift and minimum drag coefficient were achieved by using NACA4415 airfoil compared to NACA0009 airfoil. The increase of the angle of attack leads to the increase on the lift and drag coefficients for both airfoils.
Vanadium Oxide Based Electrochromic Energy Storage Devices via Facile Thin Film Preparation
(Çanakkale Onsekiz Mart University, 2023) Tuna, Asuman; Koyuncu, Sermet
The amount of energy utilized in our lives has significantly increased since the invention of electronic devices. Due to this increase in consumption, energy conservation and small-scale energy storage have become important. Smart glass technology is realized by using electrochromic devices prepared from thin films whose transmittance can be controlled under the influence of electric field. Most of the oxidized components of transition metals can be used in electrochromic devices. Vanadium, transition metal, is one of the rare compounds that show coloration in both anodic and cathodic layers. Vanadium Oxide thin films show phase change at different temperatures. With this feature, it shows anodic or cathodic differences in oxidation levels. In this study, V2O5 thin films were prepared by annealing at different thicknesses and temperatures with a spray coating device in order to measure the energy storage capacity of electrochromic devices. Prepared thin film samples were examined by atomic force microscopy (AFM) to determine their surface morphology. Optical and electrochemical properties of thin films were measured with UV-Vis spectrophotometer. Thin films were prepared for use in the anodic layer by coating PEDOT: PSS on the ITO/glass surface. Electrochromic devices were prepared by combining the anodic and cathodic layers with electrolyte gel by sandwich method. Durability and load capacity analyses of the prepared electrochromic devices were carried out.
Field management practices to produce nutritional and healthier minor crops
(Elsevier, 2023) Orhun, Gül Ebru; Maqbool, Amir; Akın, Melekşen; Eyduran, Sadiye Peral; Rakszegi, Marianna
Minor crops species are one of the basic sources of essential nutrients required in human and animal nutrition. Field management practices play crucial role in crop production affecting yield and nutritional quality. A wide range of genetic and agronomic practices are adopted to achieve optimal yield and quality which are also affected by agro-climatic conditions. Overuse of NPK fertilizers and inorganic forms of micronutrients may have adverse effects on soil pH, beneficial microbial activity and other soil properties leading to poor yield and nutritional quality of crop species. Tillage, among the field management practices, plays an important role in nutrient availability by decreasing soil compactness and bulk density. In modern agriculture different tillage conditions are reported to increase the disease spread in crop areas as well. Keeping in view this reason, it is necessary to opt for the optimal and best tillage conditions. To cope with the aforementioned problems, appropriate field management practices are essential for good crop yield and quality. In this chapter we have summarized the effect of field management practices on nutritional composition and crop health of minor crops including oat, rye, triticale, and spelt.
ENERGY EFFICIENCY IN GROUNDWATER DISCHARGE IN OPEN MINES
(Baski, 2023) Vepayev, Arslan; Deniz, Ozan
The mining industry is a crucial focus for energy conservation efforts due to its substantial potential for energy savings, as well as the predominant use of commercial energy sources in mining operations. To enhance energy efficiency within the mining sector, it is imperative to conduct effective research in areas such as energy accounting, control systems, and capacity utilization. This study investigates the utilization of Georadar, piezometer wells, and structural geology to identify optimal horizontal well placements as part of an energy-efficient approach to water management in mining activities. The paper outlines alternative methodologies for assessing and subsequently enhancing energy efficiency in metallic mines. Throughout the exploration process, hydrogeological studies play a significant role in ensuring monitoring, safety measures (such as slope stability), and operational ease in mines. The primary objective of this research is to optimize electrical energy usage by leveraging hydrogeological studies and determining the ideal dynamic water levels required for dewatering operations. A comparative analysis between horizontal water drainage systems and pump wells is conducted, with the results scrutinized to achieve the desired underground water level equilibrium. The research yielded a notable reduction in energy consumption through the adoption of horizontal drainage wells rather than vertical pump wells for dewatering purposes in Open Pit Mining Operations. Consequently, the preference for horizontal drainage wells, which align with the established optimal water level, offers distinct advantages in the context of dewatering within Open Pit Mining Operations.
Hydrochemical and Bacteriological Status of a High Altitude Karstic Cave Stream (Güvercinkaya Cave: Çanakkale, Turkey) with Aquatic Macroinvertebrates Findings
(Çanakkale Onsekiz Mart Üniversitesi, 2022) Odabaşı, Deniz Anıl; Odabaşı, Serpil; Deniz, Ozan; Çakır, Fikret; Elipek, Belgin; Arslan, Naime; Özbek, Onur; Özalp, H. Barış
Caves are laboratories for many disciplines that work in natural sciences including mineralogy, biology, hydrogeology, and archaeology. In this study, bi-monthly samplings were carried out from three smapling locations within and around the Güvercinkaya Cave, a high-altitude cave located in nortwestern Turkey, to evaluate the hydrochemical and microbiological properties and the aquatic macroinvertebrates of the cave stream. Some parameters of the water including pH, electrical conductivity, temperature, oxidation-reduction potential, dissolved oxygen were measured in-situ, while elemental (70 in total) and ionic composition of water were analyzed in the laboratory. Microbiological analyses of the cave stream were examined through analyses of total bacteria, total coliforms, fecal coliforms, fecal Streptococcus, and Escherichia coli. According to the Piper diagram of hydrochemical data, the cave stream had mainly Ca-Mg-HCO3 character, on the other hand, the Schoeller diagram indicated a common water source in Güvercinkaya cave due to the similar components of the main ionic components of the water. As a result of microbiological analysis, fecal contamination was determined, indicating an active wildlife in the cave. Additionally, several aquatic macroinvertebrates taxa, Rhynchelmis limosella, Dugesia sp., Gammarus uludagi which have non-troglobiont character were found in the cave stream. Rhynchelmis limosella detected in this study is the first record for the Turkish fauna.

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