http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15606 2026-04-23T07:04:12Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15658 New Coumarin Ring-Containing Ester Molecule: Facile Synthesis, Characterization, Computational Studies and SwissADME Prediction SARAÇ, Kamuran The aim of the study was to synthesize 4-Coumarinyl-2-methylbenzoate, elucidate the reaction mechanism, perform quantum chemical calculations, and examine the swiss adme properties of the compound. 4-Coumarinyl-2-methylbenzoate compound was synthesized by nucleophilic substitution reaction. The compound 4-coumarinyl 2-methyl benzoate has been characterized both experimentally and theoretically using quantum chemical calculations and spectral techniques. Nuclear magnetic resonances and infrared spectroscopic values of 1H and 13C in the ground state of the compound were calculated both experimentally and theoretically (density functional theory method was used when making theoretical calculations). It was observed that the calculated infrared and nuclear magnetic resonance values were compatible with the experimental values. The energy difference between the HOMO-LUMO of the 4-Coumarinyl-2-methylbenzoate compound was calculated and it was found that this difference was 1.409 Ev. Finally, swiss adme properties of 4-Coumarinyl-2methylbenzoate compound such as Molecular Mass (Size), Flexibility (FLEX), Polarity, Saturation (Insatu), Lipophilia, Water Solubility were examined. 2024-01-01T00:00:00Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15657 Investigation of Phenolic, Flavonoid and Total Antioxidant Capacity of Sumac (Rhus Coriaria L.) Plant Grown in Different Regions and Subjected to Different Preservation Methods MUHAMMED, Haval Ali; ÇAKMAK, Meltem; KARATAŞ, Fikret; ÖZER, Dursun; SAYDAM, Sinan The total amount of phenolic and flavonoid compounds and the total antioxidant capacity of sumac samples grown in different regions were determined by a spectrophotometer. Freshly ground samples were divided into three parts: the first part was analyzed immediately, the second one was oiled, and the third one was kept as is for six months. The total phenolic and flavonoid compounds were found in between 27.73-51.75 µg GAE (g dw)-1 and 16.16 -33.50 µg QE (g dw)-1, respectively, for fresh samples. In the samples that were grounded and kept for six months, the same parameters were observed to be 19.31 - 37.75 µg GAE (g dw)-1 and 10.76 21.82 µg QE (g dw)-1, respectively. IC50 and TEAC values in freshly ground sumac samples were found between 14.79-23.80 µg mL-1 and 359.30-665.62 µmol trolox (g dw)-1, respectively. IC50 and TEAC values in the samples oiled were determined to be in between 17.51 - 27.70 µg mL-1 and 306.69 - 517.40 µmol trolox (g dw)-1, respectively. From these findings, it can be said that the higher the amount of total phenolic and flavonoid compounds in the samples, the better the total antioxidant capacity. The decreases in the examined parameters of the samples with oil are lower than those kept without oiling (p>0.05). The differences in the examined parameters can be explained by the differences in geographical and ecological conditions. 2024-01-01T00:00:00Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15656 Optimizing Speech to Text Conversion in Turkish: An Analysis of Machine Learning Approaches GENÇYILMAZ, İzel Zeynep; KARAOĞLAN, Kürşat Mustafa The Conversion of Speech to Text (CoST) is crucial for developing automated systems to understand and process voice commands. Studies have focused on developing this task, especially for Turkish-specific voice commands, a strategic language in the international arena. However, researchers face various challenges, such as Turkish's suffixed structure, phonological features and unique letters, dialect and accent differences, word stress, word-initial vowel effects, background noise, gender-based sound variations, and dialectal differences. To address the challenges above, this study aims to convert speech data consisting of Turkish-specific audio clips, which have been limitedly researched in the literature, into texts with highperformance accuracy using different Machine Learning (ML) models, especially models such as Convolutional Neural Network and Convolutional Recurrent Neural Network (CRNN). For this purpose, experimental studies were conducted on a dataset of 26,485 Turkish audio clips, and performance evaluation was performed with various metrics. In addition, hyperparameters were optimized to improve the model's performance in experimental studies. A performance of over 97% has been achieved according to the F1-score metric. The highest performance results were obtained with the CRNN approach. In conclusion, this study provides valuable insights into the strengths and limitations of various ML models applied to CoST. In addition to potentially contributing to a wide range of applications, such as supporting hard-of-hearing individuals, facilitating notetaking, automatic captioning, and improving voice command recognition systems, this study is one of the first in the literature on CoST in Turkish. 2024-01-01T00:00:00Z http://dspace.beu.edu.tr:8080/xmlui/handle/123456789/15655 Bayesian Parameter Estimation for Geometric Process with Rayleigh Distribution YILMAZ, Asuman The main purpose of this study is to deal with the parameter estimation problem for the geometric process (GP) when the distribution of the first occurrence time of an event is assumed to be Rayleigh. For this purpose, maximum likelihood and Bayesian parameter estimation methods are discussed. Lindley and Markov chain Monte Carlo (MCMC) approximation methods are used in Bayesian calculations. Additionally, a novel method called the Modified-Lindley approximation has been proposed as an alternative to the Lindley approximation. An extensive simulation study was conducted to compare the performances of the prediction methods. Finally, a real data set is analyzed for illustrative purposes. 2024-01-01T00:00:00Z