WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7150

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  • Article
    Univariate Deep Learning Models for Short-Term Electricity Load Forecasting from Renewables
    (Ankara University, Faculty of Science, 2025) Kabran, Fatma Basoglu; Unlu, Kamil Demirberk
    Renewable energy offers a cost-effective, carbon-free solution for energy needs, while protecting the environment. Accurate forecasting of electricity generation from renewable sources is crucial for the efficiency of modern power grids. This study employs a univariate deep learning approach to predict daily renewable energy generation, evaluating Recurrent Neural Networks (RNNs) and Convolutional Neural Networks (CNNs) as candidate models. Five performance metrics-mean absolute error, root mean squared error, mean absolute percentage error, mean absolute scaled error and the coefficient of determination-are employed to assess the forecasting power of the algorithms. The empirical results show that CNN outperforms other models, achieving an R2 of almost 94%. This research shows that the univariate model based on historical data of electricity load generated from renewables can accurately predict day-ahead electricity load, even without meteorological data.
  • Article
    Effects of Grain Refinement, Eutectic Modification, and T6 Heat Treatment on Tribological Properties of Al8Si3Cu Alloys
    (Springer India, 2026) Gurtaran, Mikdat; Uludag, Muhammet
    In this study, the effects of grain refinement and eutectic modification on the wear behaviour of Al8Si3Cu cast alloys produced both before and after degassing were investigated in detail. Grain refinement and eutectic modification were conducted by adding AlTi5B1, Al3B, and AlSr15, respectively. Following the casting process, half of the samples were T6 heat-treated to evaluate the impact of heat treatment on their wear rate. Adhesive wear testing was conducted using a steel ball under a load of 3 N, at a speed of 8 mm/s over 20 m in dry and oily mediums. Microstructural characterisation was performed using optical microscopy and scanning electron microscopy. The results revealed that grain refinement enhances wear resistance by reducing the secondary dendrite arm spacing and strengthening the aluminium matrix. Conversely, while T6 heat treatment significantly promotes the precipitation of secondary phases and intermetallic compounds, improving wear resistance, it also results in more superficial wear on T6-treated samples, which can be attributed to insufficient surface wettability during the solution treatment stage of T6 heat treatment.
  • Article
    A Machine Learning Model for Predicting Oligoclonal Band Positivity Using Routine Cerebrospinal Fluid and Serum Biochemical Markers
    (Oxford University Press Inc, 2025) Gözgöz, Hazar; Orhan, Oğuzhan; Akan Konuk, Başak; Akan, Pınar
    OBJECTIVE: To develop and validate a machine learning model for predicting oligoclonal band (OCB) positivity using routine cerebrospinal fluid (CSF) and serum biochemical markers to improve the diagnostic accuracy and efficiency of assessing intrathecal immunoglobulin G (IgG) synthesis. METHODS: In this retrospective study (n = 1709), an ensemble model was developed using 8 refined CSF and serum parameters. Combining optimized CatBoost, XGBoost, and LightGBM classifiers, the model was trained and evaluated using a 2-phase workflow, including 5-fold cross-validation and validation on independent internal (n = 342) and external (n = 49) cohorts. RESULTS: The developed ensemble model achieved a receiver operating characteristic-area under the curve (ROC-AUC) of 0.902 on the internal test set, significantly outperforming the conventional IgG index (ROC-AUC, 0.795). At its optimal threshold, the model demonstrated an accuracy of 0.830, with a sensitivity of 0.714 and a specificity of 0.916. On the external validation cohort, it achieved 90% accuracy and 96% sensitivity. CONCLUSIONS: A novel machine learning ensemble model accurately predicts OCB positivity using routine laboratory data and demonstrates superior performance compared with the IgG index. This approach represents a significant step in applying artificial intelligence in laboratory medicine, with the potential to enhance diagnostic efficiency. Prospective, multicenter validation is essential for broader clinical implementation. © The Author(s) 2025.
  • Article
    Preparation and Characterization of Hydroxyapatite Reinforced Polymeric Scaffolds
    (Natl Inst Science Communication-NISCAIR, 2025) Firata, Duygu Doga; Ersoz, Su Turku; Burcu Alp, Fatma; Cetin, Ali Emrah; Ciftcioglu, Muhsin
    Porous HA reinforced PLA/PCL scaffolds with polymer volume percentages in the 7.0-7.6 range have been prepared by solvent-casting/salt leaching technique. The scaffolds have been characterized by conducting gravimetric measurements, FTIR analysis, TGA, X-ray diffraction analysis, compression tests, cell viability tests, and thermal and hydrolytic degradation tests in order to investigate the effect of PLA/PCL, PLA/HA, PCL/HA and PLA/PCL/HA blending on scaffold properties. Porosity of the scaffolds has been determined to be in the 83-92 percent range. The scaffold porosity has decreased with HA content. The water absorption of the scaffolds has been found to be in between 400 and 750%. The yield strength and the elastic modulus of the scaffolds have been determined to be in the 0.001-0.02 and 5.6-10.6 MPa ranges, respectively. The yield strength of the scaffolds has increased by both PCL and HA contents whereas elastic modulus has increased with PCL content but has decreased with HA content. Mechanical test results have indicated that the addition of HA has increased the strength of the scaffolds while decreasing their flexibility. The activation energies for the thermal degradation of the scaffolds have been determined to be in the 130-398 kJ/mol range and have been shown to be a function of PCL, PLA, and HA content. The hydrolytic degradation behavior of the scaffolds in acetate buffer solutions (pH=4.5) during 127 days and XRD analysis have indicated that the hydrolytic degradation occurring in the amorphous part of the surface film has been diffusion-controlled. The diffusion coefficients of the degradation products in the scaffolds have been estimated to be in the 1.21-4.95x10(-13) m(2)/s range. Cell viability test results have indicated that the composition of the composite scaffold structure has played a determining role in the prepared scaffolds.
  • Article
    The Association of Vertebrobasilar System Morphology and Geometry With the Posterior and Anterior Ischemic Stroke
    (Pera Yayıncılık Hizmetleri, 2025) Leblebici, Asım; Demirtas, İsmet; Ayyıldız, Sevilay; Ayyıldız, Behçet; Kuş, Koral Çağlar; Ayran, Ayşegül; Kurt, Mustafa Ayberk
    Objective: Morphometric and geometric variations in the vertebrobasilar system (VBS) may influence cerebral hemodynamics, potentially contributing to ischemic strokes in both anterior and posterior circulatory territories. This study aimed to investigate the association between VBS morphology and ischemic stroke localization. Methods: This retrospective observational study analyzed multidetector computed tomography angiography images from 431 patients (187 females, 244 males, mean age: 65.3 ± 14.6 years). Patients were categorized into three groups: anterior circulation ischemic stroke (ACIS, n=184), posterior circulation ischemic stroke (PCIS, n=88), and control subjects (n=159). Morphometric parameters were assessed using 3D Slicer software. Results: Significant differences in basilar artery (BA) length were observed between stroke groups and controls, with ACIS and PCIS groups exhibiting longer BA lengths (p<0.05). Males had significantly longer vertebral artery (VA) lengths than females in the control and ACIS groups (p value < 0.05). The vertebrobasilar junction angle was significantly wider in females than in males (p value = 0.046). BA bending was predominantly directed to the right across all groups, with no significant differences between the stroke and control groups. VA dominance was more frequent on the left in ACIS and the right in PCIS, while VA hypoplasia was less common in stroke patients compared to controls, contrary to previous reports. Conclusion: While certain morphometric and geometric variations in the VBS were observed, the evidence for a direct association between these characteristics and the localization of ischemic stroke was limited and inconclusive. These findings suggest that vertebrobasilar morphology may not independently determine stroke localization.
  • Article
    Developing Examination Scheduling Automation System by Using Evolutionary Computing Technique
    (Pamukkale Univ, 2012) Yaldir, Abdulkadir; Baysal, Ceyda
    In this study, manually (paperwork) and periodically prepared exam scheduling applications at universities have been taken into a computer automation system by developing a software solution. In the software developed by the authors, Evolutionary Algorithm method has been applied and university administration's specific improvement requests have also been taken into consideration while developing the software. The developed software has two parts: First part is about collecting data through the web application, and the second part is the application project, which calculates the final scheduling results. By utilizing the software, a considerable amount of time lost by manually preparing exam schedules will be saved. In addition, with the real-time connection to the student automation system database, numerous problems will be vanished, i.e. students/classes exam scheduling conflicts, etc. In the study, tables added to the current student automation system database have been explained. Additionally, by applying the genetic algorithm methods to the various parts of data have been examined along with the constraints used in the application, which are essential parts of the software. User interfaces have been designed with their sample instances. Finally, exam-scheduling table has been created and an example output of the schedule has been generated in the study.
  • Article
    İzmir’in Toplu Ulaşım Sisteminin Doğrusal Programlama ve Duyarlılık Analizi Aracılığıyla Optimizasyonu
    (Pamukkale Univ, 2024) Görgülü, Çağla; Görgülü, Lale; Duvarcı, Yavuz
    Bu çalışma, enerji tüketimi, seyahat süresi ve ulaşım ücreti perspektiflerinden toplu ulaşım problemlerine odaklanmaktadır. Çalışmanın amacı İzmir örneğinde görülen benzer ulaşım sorunlarına yönelik güzergâh açısından karşılaştırılabilir olan tramvay ve otobüs sistemleri için en iyi çözümleri sunmaktır. Ayrıca, bu çalışma farklı ulaşım tipleri arasındaki bütünleşme konusuna dikkat çekmektedir. Çalışmada kullanılan yöntemler doğrusal programlama ve duyarlılık analizidir. Bu çalışma için hem tramvay hem de otobüs hattına sahip dokuz rota belirlenmiştir. Hangi ulaşım tipinin daha uygun veya kullanışlı olduğunu, bunların olumsuz ve olumlu sonuçlarının neler olduğunu ve hangisinin çevre dostu ve yolcu bütçesine dost olduğunu incelemek üzere aynı aktarma noktalarını paylaşan rotalar seçilmiştir. Doğrusal programlama Microsoft Excel® yazılımının bir uzantısı olan çözücü aracıyla gerçekleştirilmiştir. İlk olarak, amaç fonksiyonları en küçük enerji tüketimi, en küçük rota uzunluğu ve en küçük yolcu ücreti olarak tanımlanmıştır. Elde edilen enerji tüketimi, hız ve yolcu hacmi verileri optimizasyonların kısıtlarıdır. Son olarak, bulgular duyarlılık analizi aracılığıyla değerlendirilmiştir. Hem yolcular hem ulaşım işletmecileri için otobüs ve tramvay seçenekli en iyi sonuçlar tespit edilmiştir. En uygun rotalar Fahrettin Altay-Alsancak, Fahrettin Altay-Halkapınar, Mavişehir-Bostanlı ve Egekent-Bostanlı rotalarıdır. Bu çalışma, ulaşım maliyet matrisinin yanı sıra seyahat süresi matrisini kullanarak literatüre katkı sağlamaktadır. Böylece, bu araştırma sadece mali amaçlara değil, çevresel ve sosyal amaçlara da hizmet etmektedir.
  • Article
    Citation - WoS: 2
    Square Impossible Differential Attack and Security of Aes in Known Plaintext Scenario
    (Taylor & Francis inc, 2024) Kara, Orhun
    In this work, we examine the security of the 8-round AES, under the known plaintext attack scenario, a type of cryptographic attack in which an attacker has access to the plaintext and corresponding ciphertext pairs. We present an innovative impossible differential (ID) attack technique, which utilizes a specific ID characteristic, to perform the first known plaintext attack on the 8-round AES with a 256-bit key. Additionally, we propose a new attack methodology, known as the Square Impossible Differential (SID) attack, to enhance the effectiveness of the ID attacks on AES in chosen ciphertext or plaintext scenarios. The SID attack is a combination of a square attack and an ID attack. Our methodology introduces various new approaches, including the key indicator vectors, eliminating the key candidate through the Meet-in-The-Middle technique and mounting the guess and determine attack through the hash tables for the two-round decryption of one column of AES while determining the subkeys constituting the impossible differential characteristic for a given plaintext/ciphertext difference pair. Our approach demonstrates lower computational complexity compared to previous methods, and our analysis shows that the complexities of our known plaintext attack and SID attack are estimated to be 2220 and 2209, respectively.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Experimental Investigation of Naca 4415 Airfoil Using Vibration Data for Stall Detection
    (Emerald Group Publishing, 2023) Ayaz Ümütlü, Hatice Cansu; Kıral, Zeki; Karadeniz, Ziya Haktan
    PurposeThe purpose of this study is to identify the possible relation between the vibration and the stall by using the vibration response of the airfoil. For this purpose, the root mean square values of the acceleration signals are evaluated to demonstrate the compatibility between the stall angles and the vibration levels. Design/methodology/approachAn experimental study is conducted on NACA 4415 airfoil at Reynolds numbers 69e3, 77e3 and 85e3. Experiments are performed from 0 & DEG; to 25 & DEG; of the angles of attack (AoA) for each Reynolds number condition. To observe the change of the vibration values at the stall region clearly, experiments are performed with the AoA ranging from 10 & DEG; to 25 & DEG; in 1 & DEG; increments. Three acceleration sensors are used to obtain the vibration data. FindingsThe results show that the increase in the amplitude of the vibration is directly related to the decrease in lift. These findings indicate that this approach could be beneficial in detecting stall on airfoil-type structures. Originality/valueThis study proposes a new approach for detecting stall over the airfoil using the vibration data.
  • Article
    Assessment of Undergraduate Health Students' Perception and Satisfaction on Training and Participation in Community Health Outreach
    (Springer, 2023) Adegbore, Abidemi Kafayat; Adedokun, Amudatu Ambali; Adegoke, Juliet Ifeoluwa; Lawal, Maruf Ayobami; Oke, Muse
    AimThe need to improve training of health professionals has increased in recent years due to increasing frequencies of public health events. Consequently, a descriptive cross-sectional survey was carried out to determine the level of satisfaction and knowledge acquired by undergraduate students in the health sciences during a community health outreach program.Subject and methodsStudents were invited to complete an online-administered questionnaire (consisting of both open- and closed-ended questions) to assess their perceptions and experiences on the community health outreach program. Additionally, the survey was carried out to assess the quality of training provided and obtain suggestions for further improvements. Responses were collected and analysed using Microsoft Excel.ResultsMost respondents (>83%) reported satisfaction with the community diagnosis and community intervention briefing and training sessions. All respondents reported familiarity with standard community health outreach instruments and were capable of identifying environmental health risk factors that may contribute to the spread of communicable diseases. Interestingly, respondents reported greater appreciation of health challenges faced by rural communities. However, respondents expressed dissatisfaction with the duration of the outreach program (24%) and funding (15%).ConclusionAlthough respondents reported overall satisfaction with the organization and execution of the health outreach program, certain aspects of the program were deemed unsatisfactory. Despite the shortcomings, we believe that our student-centred learning strategy is readily adaptable for training future healthcare professionals and improving health literacy of rural communities, particularly in sub-Saharan Africa.