Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Conference Object Machine Learning-Based Antenna Selection and Secrecy Capacity Analysis(Institute of Electrical and Electronics Engineers Inc., 2025) Erdurak, Burak; Erdoǧan, Eylem; Gürkan, FilizThe performance of machine learning methods was analyzed to optimize antenna selection in wireless communication systems, and system's secrecy performance was observed. To enhance the antenna selection process, Deep Neural Networks (DNNs), Convolutional Neural Networks (CNNs), and the KNearest Neighbors (KNN) algorithm were utilized. Channel vectors were used as model inputs, aiming to select the most optimal transmission path among N possible candidates. During the training phase, the antenna with the highest Signal-to-Noise Ratio (SNR) was selected for data labeling. The performance of Single-Input Multiple-Output (SIMO), Multiple-Input SingleOutput (MISO), and Multiple-Input Multiple-Output (MIMO) system architectures was evaluated using model accuracy and the F1-score. Additionally, the secrecy capacity corresponding to the selected antennas was computed, demonstrating the feasibility of secure communication. The results indicate that deep learningbased methods achieved higher accuracy, with the CNN model emerging as the most successful approach, reaching an accuracy of over 95% across all system configurations. © 2025 Elsevier B.V., All rights reserved.Article Effect of Methionine and Lysine Supplementation on Performance and Intestinal Morphometrics of Finisher Broiler Chickens Fed Diets Containing Processed Cassava Peel Meal(CSIRO Publishing, 2025) Adebowale, T.O.; Arowolo, M.A.; Adekola, M.; Adeleye, T.; Oke, O.E.Context: The current high prices of conventional feedstuffs in developing countries seems to warrant intensified efforts to find sustainable alternatives to the major feed ingredients that would support performance without compromising gut health, reduce cost of production and promote a sustainable environment. Aims: The aim of the study is to evaluate the performance and health-related responses of finisher broiler chickens to the dietary replacement of corn with processed cassava peel meal (high- quality cassava peel meal) at 50% inclusion level, supplemented with methionine and lysine. Methods: Three hundred and twenty Cobb500 broiler chickens were allocated to four dietary treatments on a weight equalization basis. Each treatment was replicated eight times. A control diet based on corn and soybean meal was formulated to meet the recommended digestible methionine and lysine specification of 4.0 and 0.96 g kg−1respectively (VenCobb 500 Broiler Management Guide, Cobb-Vantress Inc., Siloam Spring, AR) for the finisher phase. The corn in the control diet was replaced with cassava peel meal at 50% replacement level in three other treatments (Diet 2–4). Diets 2–4 were then formulated to contain 100%, 112.5% and 125% of the recommended digestible methionine and 100%, 106.25% and 112.5% of the recommended digestible lysine, yielding 4.0, 4.4, and 4.8 g kg−1digestible methionine respectively, and 0.96, 1.02, and 1.08 g kg−1digestible lysine respectively, for the finisher phase. Key results: The highest bodyweight gain, improved feed conversion ratio and increased duodenal and jejunal villus height:crypt depth ratio was found in birds fed Diet 4. The lactobacillus count was highest in birds fed Diet 4 and total bacteria counts was highest in birds fed Diet 2. The feed cost per kilogram weight gain was least for the birds fed diets containing the processed cassava peel meal. However, morphological changes were observed in the liver and intestinal tissues of the birds. Conclusion: The study showed that the adequate supplementation of methionine and lysine to processed cassava peel meal can improve production performance of finisher broiler chickens but may not prevent morphological changes in the liver and intestine of the birds. Implication: The result implied that processed and fortified cassava peel meal can reduce high dependence on maize in the production of finisher broiler chickens, while mitigating the enviromental challenges associated with the disposal of the agrowaste. The morphological changes in the liver and intestine of the birds require further investigation. © 2025 Elsevier B.V., All rights reserved.Conference Object Citation - Scopus: 1Observed Performance of a RC Wall-Frame Building During the February 2023 Turkey Earthquake and Performance Improvement Using FRPs(International Institute for FRP in Construction (IIFC), 2023) Tura, C.; Sahinkaya, Y.; Güllü, M.F.; Demir, U.; Orakcal, K.; Ilki, A.In this study, results of nonlinear response history analysis are presented for an existing RC wall-frame building, which has suffered collapse-level damage during the devastating February 2023 Kahramanmaras earthquakes. Performance analysis results for two building configurations are compared; first for the existing building configuration generated upon on-site observations, and second, for a hypothetical configuration in which the structural walls and columns are retroffited using externally-bonded FRP sheets. Analysis results reveal that in its existing configuration, mostly due to detailing deficiencies, a collapse-level performance was not unexpected; whereas FRP strengthening of the building would have resulted in collapse-prevention performance. © CICE 2023 - 11th International Conference on FRP Composites in Civil Engineering. All rights reserved.Conference Object Quote Detection: a New Task and Dataset for Nlp(Association for Computational Linguistics, 2023) Tekir, S.; Güzel, A.; Tenekeci, S.; Haman, B.U.Quotes are universally appealing. Humans recognize good quotes and save them for later reference. However, it may pose a challenge for machines. In this work, we build a new corpus of quotes and propose a new task, quote detection, as a type of span detection. We retrieve the quote set from Goodreads and collect the spans through a custom search on the Gutenberg Book Corpus. We run two types of baselines for quote detection: Conditional random field (CRF) and summarization with pointer-generator networks and Bidirectional and Auto-Regressive Transformers (BART). The results show that the neural sequence-to-sequence models perform substantially better than CRF. From the viewpoint of neural extractive summarization, quote detection seems easier than news summarization. Moreover, model fine-tuning on our corpus and the Cornell Movie-Quotes Corpus introduces incremental performance boosts. Finally, we provide a qualitative analysis to gain insight into the performance. © 2023 Association for Computational Linguistics.Review Citation - WoS: 3Citation - Scopus: 4Predictive Video Analytics in Online Courses: a Systematic Literature Review(SPRINGER, 2023) Yurum, Ozan Rasit; Taskaya-Temizel, Tuğba; Yildirim, SonerThe purpose of this study was to investigate the use of predictive video analytics in online courses in the literature. A systematic literature review was performed based on a hybrid search strategy that included both database searching and backward snowballing. In total, 77 related publications published between 2011 and April 2023 were identified. The findings revealed an increase in the number of publications on predictive video analytics since 2016. In the majority of studies, edX and Coursera platforms were used to collect learners' video interaction data. In addition, computer science was shown to be the top course domain, whilst data collection from a single course was found to be the most common. The results related to input measures showed that pause, play, backward, and forward were the top in-video interactions, whilst video transcript and subtitle were the least used. Learner performance and dropout were the primary output measures, whereas learning variables such as engagement, satisfaction, and motivation were investigated in only a few studies. Furthermore, most of the studies utilized data related to forums, navigation, and exams in addition to video data. The top algorithms used were Support Vector Machine, Random Forest, Logistic Regression, and Recurrent Neural Networks, with Random Forest and Recurrent Neural Networks being two rising algorithms in recent years. The top three evaluation metrics used were Accuracy, Area Under the Curve, and F1 Score. The findings of this study may be used to aid effective learning design and guide future research.Review Citation - WoS: 18Citation - Scopus: 18A Review on New Cobalt-Free Cathode Materials for Reversible Solid Oxide Fuel Cells(Chulalongkorn Univ, Metallurgy & Materials Science Research Inst, 2023) Akkurt, Sedat; Sındırac, Can; Özmen Egesoy, Tuğce; Ergen, EmreThe exponential growth in the requirement of fuel cells and batteries leads to increased demand for cobalt due to its common use in high-performance Li-ion batteries and high-temperature fuel cells/electrolyzers. This sharp increment in demand raises concern about the availability of limited reserves of cobalt which can impact the price of cobalt. Moreover, the geographic limitations of cobalt resources may endanger the whole supply chain. In addition to all those, huge moral issues of cobalt mining are also another problem. Hence, leading battery, fuel cells and electrolyzer manufacturers are looking for sustainable alternatives to reduce cobalt dependency. A more specific limitation is shown in Solid Oxide Fuel Cells (SOFCs) cathode materials that contain cobalt. Incompatibilities have already been observed between the cathode materials containing cobalt and the electrolytes in terms of the thermal expansion coefficient mismatch during the transition of the operating temperature from high to low. An advantage of low operating temperatures is the reduction of material costs compared to high temperature. Increasing the electrochemical performance of the cell and eliminating thermal expansion coefficient difference problems are in concert aimed at the development of cobalt-free cathode materials. Therefore, cobalt-free cathode materials are vital for the sustainability of SOFCs and green transition of the energy sector since they can be used as cathode and anode material in symmetrical SOFCs which is also known as reversible SOFC (RSOFC). In this review, we comprehensively summarize the recent advances of cobalt-free perovskite cathode materials for intermediate temperature RSOFCs.Article Citation - WoS: 45Citation - Scopus: 51Experimental Investigation of the Effect of Graphene/Water Nanofluid on the Heat Transfer of a Shell-And Heat Exchanger(Wiley-Hindawi, 2023) Zolfalizadeh, Mehrdad; Heris, Saeed Zeinali; Pourpasha, Hadi; Mohammadpourfard, Mousa; Meyer, Josua P. P.The most common type of heat exchanger used in a variety of industrial applications is the shell-and-tube heat exchanger (STHE). In this work, the impact of graphene nanoplate (GNP)/water nanofluids at 0.01 wt.%, 0.03 wt.%, and 0.06 wt.% on the thermal efficiency, thermal performance factor, pressure drop, overall heat transfer, convective heat transfer coefficient (CVHTC), and heat transfer characteristics of a shell-and-tube heat exchanger was examined. For these experiments, a new STHE was designed and built. The novelty of this study is the use of GNPs/water nanofluids in this new STHE for the first time and the fully experimental investigation of the attributes of nanofluids. GNP properties were analysed and confirmed using analyses including XRD and TEM. Zeta potential, DLS, and camera images were used to examine the stability of nanofluids at various periods. The zeta potential of the nanofluids was lower than -27.8 mV, confirming the good stability of GNP/water nanofluids. The results illustrated that the experimental data for distilled water had a reasonably good agreement with Sieder-Tate correlation. The maximum enhancement in the CVHTC of nanofluid with 0.06 wt.% of GNP, was equal to 910 (W/m(2)K), an increase of 22.47%. Also, the efficiency of the heat exchanger for nanofluid at 0.06 wt.% improved by 8.88% compared with that of the base fluid. The heat transfer rate of the nanofluid at maximum concentration and volume flow rate was 3915 (J/kg.K), an improvement of 15.65% over the base fluid. The pressure drops increased as the flow rate and concentration of the nanofluid increased. Although increasing the pressure drop in tubes would increase the CVHTC, it would also increase the power consumption of the pump. In conclusion, nanofluid at 0.06 wt.% had good performance.Article Citation - WoS: 15Citation - Scopus: 18Achieving Query Performance in the Cloud Via a Cost-Effective Data Replication Strategy(Springer, 2021) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, TolgaMeeting performance expectations of tenants without sacrificing economic benefit is a tough challenge for cloud providers. We propose a data replication strategy to simultaneously satisfy both the performance and provider profit. Response time of database queries is estimated with the consideration of parallel execution. If the estimated response time is not acceptable, bottlenecks are identified in the query plan. Data replication is realized to resolve the bottlenecks. Data placement is heuristically performed in a way to satisfy query response times at a minimal cost for the provider. We demonstrate the validity of our strategy in a performance evaluation study.Article Citation - WoS: 24Citation - Scopus: 31Dynamic Replication Strategies in Data Grid Systems: A Survey(Springer Verlag, 2015) Tos, Uras; Mokadem, Riad; Hameurlain, Abdelkader; Ayav, Tolga; Bora, ŞebnemIn data grid systems, data replication aims to increase availability, fault tolerance, load balancing and scalability while reducing bandwidth consumption, and job execution time. Several classification schemes for data replication were proposed in the literature, (i) static vs. dynamic, (ii) centralized vs. decentralized, (iii) push vs. pull, and (iv) objective function based. Dynamic data replication is a form of data replication that is performed with respect to the changing conditions of the grid environment. In this paper, we present a survey of recent dynamic data replication strategies. We study and classify these strategies by taking the target data grid architecture as the sole classifier. We discuss the key points of the studied strategies and provide feature comparison of them according to important metrics. Furthermore, the impact of data grid architecture on dynamic replication performance is investigated in a simulation study. Finally, some important issues and open research problems in the area are pointed out.