Istanbul Technical University
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Examining correlation between online readiness and content-type preferences of adult learners in an online learning environment
No full texthttps://doi.org/10.1080/10494820.2025.245443
Efficiency Analysis and Classification of an Airline’s Email Campaigns Using DEA and Decision Trees
No full textCampaigns significantly impact overall company performance, making the measurement and prediction of campaign efficiency essential. This study proposes an integrated methodology that combines efficiency measurement with efficiency prediction for airline email campaigns. In the first part of the methodology, Data Envelopment Analysis (DEA) was applied to real airline campaign data to evaluate efficiency; this is the first study to analyze email campaign efficiency in this context. In the second part of the methodology, decision tree algorithms were employed to classify historical campaign data based on DEA scores, with the aim of predicting the efficiency of future campaigns—a novel approach in this context. A core dataset of 76 airline email campaigns with six inputs and two outputs was analyzed using output-oriented CCR (Charnes, Cooper, Rhodes) and BCC (Banker, Charnes, Cooper) models; 26 and 46 campaigns were identified as efficient, respectively. The analysis was further segmented by group size, seasonality, and route type. Efficient campaigns were then ranked via super-efficiency, and sensitivity analysis assessed variable and campaign effects. For prediction, decision tree algorithms (J48 (C4.5), C5.0, and CART (Classification and Regression Trees)) were employed to classify campaigns as efficient or inefficient, using DEA efficiency scores as the target variable and DEA inputs as attributes, with classification performed for both BCC and CCR core models. Class imbalance was addressed with SMOTE, and models were evaluated under stratified 10-fold cross-validation. After balancing, the BCC core model (BCC_C) yielded the most reliable predictions (overall accuracy 76.3%), with J48 providing the most balanced results, whereas the CCR core model (CCR_C) remained weak across algorithms.https://doi.org/10.3390/info1611096
The Cost of the Initial Investment Affecting the Selection of Tunneling Methods
No full texthttps://doi.org/10.1007/978-3-031-89114-4_
Machine learning application with Bayesian regularization for predicting pressure drop in R134a's annular evaporation and condensation
No full texthttps://doi.org/10.1007/s40430-025-05527-8https://avesis.yildiz.edu.tr/publication/details/927d96b1-923e-4982-8596-51e40e22085d/oaihttps://avesis.yyu.edu.tr/publication/details/927d96b1-923e-4982-8596-51e40e22085d/oa
A Key Update Mechanism for Social Media Based on Tangle
No full texthttps://doi.org/10.1109/balkancom65827.2025.1118598
Recent Advances in the Multifunctional Properties and Applications of Carbon Nanotube/Graphene Hybrid Polymer Nanocomposites
No full textABSTRACTGraphene and carbon nanotubes (CNTs) have emerged as highly regarded carbon fillers in the field of polymer nanocomposites (PNCs), owing to their exceptional structural and functional characteristics. Achieving a high‐quality nanofiller dispersion inside the polymer matrix is critical for developing top‐performing PNCs. Combining CNTs and graphene with varied dimensions could prove to be the most favorable nanofillers in the preparation of high‐performance nanocomposites, owing to their synergistic outcome through the development of an effective three‐dimensional (3D) structure. The issues related to nanofillers and their functionalization techniques were first discussed. Then, commercially feasible fabrication methods of PNCs, including melt compounding, solution mixing, in situ polymerization, and layer‐by‐layer (LbL) assembly, were briefly summarized. This paper mainly reviews the effectiveness of hybrid CNT/graphene on mechanical, thermal, electrical, and EMI‐shielding properties and applications of PNCs. The primary motivations for ternary nanocomposites are to (1) achieve greater performance improvement through synergistic effects, (2) attain multifunctionality, (3) improve scalability, and (4) lower manufacturing costs.https://doi.org/10.1002/pc.7015
Comparative Analysis of Protein Extraction Protocols for Olive Leaf Proteomics: Insights into Differential Protein Abundance and Isoelectric Point Distribution
No full textPlant proteomics studies face two major challenges: limited databases due to the need for sequenced genomes and the difficulty in obtaining high-quality protein extracts. Olive (Olea europaea), a key species in Mediterranean flora known for its rich biochemical content, presents additional complexity due to its lipidic structure and high levels of inhibitory compounds that hinder protein extraction. Consequently, various studies have focused on optimizing the protein extraction methods for olives. While different extraction protocols exist for leaf proteome analysis, their compatibility with LC-MS/MS has been scarcely studied. This work was carried out to compare three protein extraction protocols for LC-MS/MS analysis using olive (O. europaea L) leaf tissue. Denaturing SDS (Method A), physiological CHAPS (Method B), and phenolic TCA/acetone (Method C) were evaluated with LC-MS/MS data. The quantitative comparisons of the three extraction methods revealed that Protocol A gave the greatest yields. According to the results obtained, Protocol A uniquely identified 77 proteins, Protocol B identified 10 unique proteins, and Protocol C identified 19 unique proteins. Similarly, the peptide sequence analysis showed that Protocol A uniquely identified 208 peptide sequences, Protocol B identified 29, and Protocol C identified 36. Moreover, reversed-phase high-performance liquid chromatography (RP-HPLC) results suggest that Method A may be more efficient in removing and retaining hydrophobic proteins. Overall, Protocol A demonstrated greater sensitivity, efficiency, and reproducibility in LC-MS/MS analysis.https://doi.org/10.1021/acsagscitech.4c00642https://pubmed.ncbi.nlm.nih.gov/40405867http://dx.doi.org/10.1021/acsagscitech.4c0064
Multi-UAV Aided LEO Satellite Communication Network Analysis Based on Stochastic Geometry
No full texthttps://doi.org/10.1109/tvt.2025.360626
A Late Holocene multi-proxy speleothem record from NW Türkiye
No full textNW Türkiye is uniquely positioned between climatic influences from the North Atlantic, Mediterranean and Eurasia. Variability in climate systems through the Late Holocene is thought to have influenced major historical transitions, such as the ‘Bronze Age Collapse’, and during periods including the ‘Roman Climate Anomaly’ and the ‘Little Ice Age’. The region is noteworthy considering its geographical and historical significance over the last 4,000 years as a landscape for Ancient Greece Colonisation, the Roman Byzantine and Ottoman Empires and proximity to the common focal-point of modern-day Istanbul (Byzantium, Constantinople) which received much of its water from the cave’s locality. With the Eastern Mediterranean a hotspot for agricultural drought (Dabanlı et. al; 2017), which has impacted societies historically, the region warrants the study of spatio-temporal human-climate interactions.Given the scarcity of sub-decadal palaeoclimate records regionally, and heterogeneity of Eastern Mediterranean climate generally (Jacobson et. al; 2021), stalagmite U-1 from Uzuntarla cave in Thrace helps fill this gap. Speleothem U-1 was dated using a combination of U/Th and 14C dates. The chronology is further refined by aligning distinct growth-shifts with well-dated and strong historical earthquakes. Using the combined evidence of calcite fabric and growth laminae changes, stable isotope (δ13C, δ18O), trace elements (Mg/Ca, Sr/Ca, P/Ca) and fluid-inclusion analysis, we find that U-1 is highly sensitive to changes in cold-season regional precipitation, seasonality and temperature. For example, increases in δ13C often coincide with narrowing of growth-laminae and increased Sr/Ca suggesting a unified influence by reduced drip-rate during poor recharge conditions. Effective infiltration is between Oct:Mar, making δ18O a combined indicator for Fall:Winter:Spring seasonality balance and temperature. Initial fluid inclusion temperature estimates are promising with work ongoing, however other factors are worth discussing such as aeolian oceanic Mg inputs. Initial results, often complimenting other regional palaeoclimate records, paints a picture of dynamic changes in climate over the last 3,900 years BP spanning key historical transitions. Speleothem U-1 describes a large shift in aquifer-recharge and seasonality preceding the Bronze Age Collapse impacting SW Asia around 1190 BCE. Recharge then peaks anomalously in 650-690 BCE during the Homeric Minimum, coinciding with the Greek Colonisation and Byzantium’s founding ~667 BCE. The acclaimed Roman Climate Anomaly (150 BCE-200 CE) is without wet-anomalies but stable for U-1, with later evidence of aridification. Wetter and stable conditions follow during 200-600 CE, a period encompassing defining historical events including the establishment of Constantinople as a powerhouse of the East Roman Empire and major infrastructure development including aqueduct expansion into Thrace. The Medieval Climate Anomaly (950-1250 CE) is defined by wet conditions during 760-1100 CE transitioning into lower aquifer recharge between 1100-1220 CE. Finally, the Little Ice Age (1400-1700 CE) shows highly variable conditions, but generally transitions from a wetter and colder period to lower aquifer recharge between 1220 and 1760 CE. REFERENCESDabanlı et. al; 2017. Long-term spatio-temporal drought variability in Turkey. Journal of Hydrology, 552, pp.779-792.Jacobson et. al; 2021. Heterogenous late Holocene climate in the Eastern Mediterranean—the Kocain Cave record from SW Turkey. Geophysical Research Letters, 48(20), p.e2021GL094733.https://doi.org/10.5194/egusphere-egu24-1795
Reconstructing the Late Holocene paleoclimate and paleoenvironmental changes in Southeastern Anatolia (Gölbaşı, Adıyaman, SE Türkiye) through fossil pollen and non-pollen palynomorphs (NPP) 
No full textFossil pollen and non-pollen palynomorphs are useful indicators to reconstruct paleoclimate and paleoenvironmental changes. In palynological investigations, evaluating the difference between anthropogenic effects and paleoclimatic conditions is important for understanding the causes of paleoecological changes during the Holocene. Non-pollen palynomorphs can be observed in pollen slides owing to their acid-resistant organic structure, providing complementary insights into erosion, pastoralism, cultivation, and trophic state in wetlands.This study investigates paleoclimate and paleoenvironmental variations in the Gölbaşı Basin, located in the East Anatolian Fault Zone (EAFZ), through palynological analyses that have been done on two sediment cores taken from Lakes Gölbaşı and Azaplı for the first time. The GLB-01 core, obtained from Lake Gölbaşı and dating back to 1995 +/- 35 cal BP, measures 129 cm in length and is predominantly composed of uniform, laminated reddish-brown mud. In comparison, the AZP-03 sediment core from Lake Azaplı spans 138 cm, with laminated green mud observed from the core's surface down to 96 cm depth. At the lowermost level of the AZP-03 core, peat deposits are present, containing gastropod shells (Gyraulus sp.) and wood remains attributed to Quercus bratii/libani, along with sandy detrital inputs. The top of the peat deposit dates back to 2889 +/- 27 cal BP. According to this study, cultivated trees are identified by Juglans, Pistacia, and Olea europea, while anthropogenic plants are represented by Caryophyllaceae, Amaranthaceae, Sanguisorba minor type, Centaura, Polygonum, and Plantago. Alongside the analysis of pollen grains, 39 sediment samples have been examined for Non-Pollen Palynomorphs (NPPs) at various percentages along the sediment cores. Notably, green algae Pediastrum, free-floating green algae Spirogyra, and the filter feeder Bosmina sp. exhibit high proportions within the initial 30 cm of the cores. Furthermore, Glomus, a mycorrhizal fungus linked to soil erosion, increases in abundance where herbaceous pollens are prevalent. Herbaceous plants, characterized by non-woody stems, may not provide the same level of soil protection as trees. In the absence of a dense tree canopy, herbaceous plants may be less effective in preventing soil erosion. The increase in Glomus in the cores could be indicative of a response to the changing soil conditions resulting from erosion. This study is supported by the ITU- Scientific Research Projects Coordination Unit (Project Number: MYL-2022- 43676) and TÜBİTAK Project (Grant Number: 121Y287). https://doi.org/10.5194/egusphere-egu24-35