Yıldız Technical University Research Information System
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Developing a Decision Support System for Small Parcel Transportation Supplier Selection Based on Decomposed Fuzzy AHP and TOPSIS Methods
No full textWith the rapid growth of e-commerce, small parcel transportation has become a critical aspect of logistics operations. Selecting the most suitable supplier plays a vital role in minimizing costs, improving delivery efficiency, and ensuring customer satisfaction. This study presents a Decision Support System (DSS) for evaluating and selecting small parcel transportation suppliers using a Decomposed Fuzzy Analytic Hierarchy Process (D-FAHP) and the TOPSIS (Techniques for Order Preference by Similarity to an Ideal Solution) method. The proposed approach decomposes decision-making into hierarchical steps, ensuring a structured and reliable supplier evaluation process. In the study, cost, delivery time, reliability, service quality, and technology are used as evaluation criteria. The D-FAHP method is employed to determine the importance degrees of the criteria, while the TOPSIS method is used to measure the performance of the alternatives under the selected criteria. The results provide insights into the key factors influencing supplier selection and demonstrate the effectiveness of the DSS in identifying the optimal transportation provider
Simultaneous Ni-TiO2 coated electrodes for hydrogen evolution reaction in alkaline media
No full textHydrogen is recognized as a clean and reliable energy option, and its efficient and effective production is essential for future energy systems and their deployments. In this study, Ni and Ni-TiO2 coatings are prepared on stainless steel substrates by co-electrodeposition at different deposition times and are evaluated for the hydrogen evolution reaction (HER) in alkaline media. The XRD and FESEM analyses confirm the beneficial role of TiO2 incorporation. The Ni-TiO2 electrode deposited for 7 min shows the best performance, achieving a hydrogen production rate of 51 mL cm−2 h−1, with an energy efficiency of 21.45 %, an exergy efficiency of 21.42 %, a Faraday efficiency of 94.97 %, a Tafel slope of 0.118 V dec−1, an exchange current density of 1.04x10−4 A cm−2, and a charge-transfer resistance of 0.068 Ω cm2. The AGREE score of 0.64 further highlights the environmental advantages. This study also represents the first application of the AGREE metric to Ni-TiO2 co-electrodeposited electrodes
Antimicrobial and Antioxidant Electrospun Membrane Incorporating Silver and Copper Complexes of Phenylboronic Acid-Functionalized 4,5-Diazafluorene Ligand
No full textThermally crosslinked polyacrylic acid (PAA)-polyvinyl alcohol (PVA) nanofibrous (NFC) membranes were developed via electrospinning for potential wound dressing applications with antioxidant and antimicrobial properties. Silver and copper complexes (AgSK and CuSK) of a phenylboronic acid-functionalized 4,5-diazafluorene ligand (SK) were synthesized, characterized, and incorporated into the membranes. SEM imaging revealed uniform, bead-free nanofibers with an average diameter of 725.35 ± 173.79 nm. FTIR analysis confirmed the successful incorporation of compounds through characteristic C═N stretching bands at 1620–1630 cm−1. DPPH assay showed that SK, AgSK, and CuSK exhibited antioxidant activities of 54.6 ± 2.5%, 88.4 ± 3.5%, and 79.6 ± 3.4% at 90 min, respectively. Incorporation into the nanofibers did not significantly alter antioxidant performance. Antimicrobial activity was assessed against Escherichia coli, Staphylococcus aureus, and Candida albicans. AgSK showed the strongest inhibition, with MIC values of 62.5, 31.25, and 125 µg/mL, respectively. AgSK-loaded membranes (AgSK-NFC) demonstrate antimicrobial activity with > 98% reduction in all tested strains. Biocompatibility tests with L929 fibroblasts showed improved cell viability upon membrane incorporation. The membranes also exhibited high swelling capacity, good water resistance, and sustained release over 7 days. With this study, for the first time, the use of 4,5-diazafluorene and its metal complexes in nanofibrous membranes has been demonstrated. Thus, an interdisciplinary approach combining materials science and coordination chemistry is established, broadening the scope for future developments in nanofiber-based technologies
Hierarchical Cascade Deep Learning for EMG-Based Behavioral Biometrics: Gesture and Subject Classification
No full textThe integration of electromyography (EMG) signals into biometric recognition has garnered significant attention due to their potential for highly secure and reliable identification. Unlike vision-based methods like cameras, EMG is immune to lighting conditions, clothing, or occlusions. This study presents a hierarchical cascade deep learning framework aimed at simultaneously performing hand gesture recognition and subject-specific biometric classification. Utilizing the publicly available Gesture Recognition and Biometrics ElectroMyogram (GRABMyo) dataset, which encompasses diverse EMG recordings from 43 individuals performing 17 unique gestures, this study proposes a two-staged classification approach. The first stage concentrates on recognizing the hand gesture, succeeded by a gesture-specific model that subsequently categorizes the subject associated with the identified gesture. The experimental results demonstrate the effectiveness of the proposed model, which achieved an average accuracy of 71.62% across gesture and subject classification, representing an improvement of approximately 5% and 21% compared to conventional single-model and multi-task strategies evaluated in this study, highlighting this approach’s effectiveness in handling the variability of EMG signals across different gestures and subjects. The findings underscore the potential of the proposed methodology for enhancing EMG-based biometric recognition systems.</p
Sensitive determination of lead in an herbal tea matrix utilizing carbon doped CuO nanoparticles as solid phase adsorbent
No full textThis study presents the development of an efficient solid-phase microextraction (SPME) strategy using C-doped CuO nanoparticles for the trace determination of lead by using flame atomic absorption spectrometry (FAAS). The C-doped CuO nanoparticles were synthesized by the precipitation method. The morphological and structural properties of the nanoparticles have been investigated by XRD, SEM, and EDX analysis. A comprehensive optimization study was conducted to maximize the extraction efficiency by evaluating various experimental factors including buffer solution volume/type, mixing duration, sample volume, adsorbent quantity, and desorption solution volume/concentration. Under the optimum conditions, the limit of detection (LOD), the limit of quantification (LOQ), and the linear dynamic range were calculated as 0.011 mg/kg, 0.035 mg/kg, and 0.03–0.40 mg/kg, respectively. For the proposed SPME procedure, an enhancement factor of 82-fold was calculated by comparison of the detection sensitivity of the developed method with direct FAAS measurements
Kavramsal Değişim Stratejileri Kullanılarak Yapılan Öğretimin 3. Sınıf Öğrencilerinin Kavramsal Anlamalarına ve Başarılarına Etkisinin Belirlenmesi
No full textIB okullarında çalışan öğretmenlerin IB standartları gereği teknoloji kullanımlarının, yeterlik ve mesleki doyum bağlamlarında incelenmesi
No full textAnalysis of the Arequipa, southern Peru, earthquake of 23 June 2001 by using GNSS data
No full textPeru is located above the damaging Peru–Chile Trench, which is the line where the Nazca Plate is subducting under the South American Plate. The two plates are approaching one another at a velocity of around 78 millimetres each year. There is a history of really big earthquakes in southwest Peru. The Arequipa, southern Peru, earthquake of 23 June 2001 had a moment magnitude of 8.4, a maximum Mercalli severity of VIII (severe), and occurred at 20:33:15 UTC (15:33:15 local time). It was the worst earthquake to ever strike the world since the 1965 Rat Islands earthquake and the most destructive earthquake to strike Peru since the disastrous Ancash earthquake of 1970. In this study, the horizontal and vertical displacements before and after the Arequipa, southern Peru, earthquake were analysed (kinematic GNSS results were compared with static GNSS results). As a result of these GNSS investigations (pre-motion on 20–21 June 2001), the obtained GNSS data for the precursor of the Arequipa earthquake were used. The AREQ IGS station before the earthquake, the movement in the horizontal components that occurred on 20–21 June 2001, and the decrease of this movement on 22 June 2001 seem to be a harbinger of the earthquake. In addition, the effects of the earthquake that occurred on 23 June 2001 were continued with aftershocks on 24 June 2001. In addition, this study may serve as a basis for understanding potential precursory patterns in this region.</p
