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Gas Flow Sensing with a Piezoresistive Silicon Nanowire-Based MEMS Force Sensor
No full texthttps://doi.org/10.1109/mems61431.2025.1091765
Hydroelastic analysis of partially or totally immersed Mindlin plates with a hybrid isogeometric-based approach
No full textIn this study, the dynamic characteristics of a cantilevered Mindlin plate, partially or totally in contact with fluid on both sides, are examined using the proposed hybrid isogeometric finite element – boundary element framework. The interaction problem is divided into two parts through the implementation of the linear hydroelasticity theory, allowing for the independent treatment of structural and fluid problems. In the structural part of the analysis, the thick plate is modeled as first-order shear deformable by adopting Reissner–Mindlin plate theory, with the material assumed to be homogeneous and isotropic. The resulting eigenvalue problem is then solved by the isogeometric finite element method (IGAFEM). In the second part of the analysis, assuming the fluid is ideal and incorporating the in vacuo dynamic characteristics as boundary conditions, fluid-structure interaction effects are determined by the isogeometric boundary element method (IGABEM) in terms of generalized added mass coefficients. Subsequently, parametric studies for various plate thicknesses and submergence depths are conducted. The analysis reveals that wet natural frequencies differ noticeably from their in vacuo counterparts due to the presence of the free surface of the fluid. In addition, the effect of the radiated free surface waves from the vibrating structure are included into the mathematical model by imposing linearized free surface condition, through the frequency-dependent added mass and hydrodynamic damping effects of the fluid. The numerical accuracy of the proposed approach is verified against the commercial finite element software ANSYS, showing favourable agreement in the predicted natural frequencies and corresponding mode shapes.https://doi.org/10.1177/10812865241309300https://hdl.handle.net/11697/26065
Generating Landslide Archive Inventories Using Web Scraping and NLP Techniques for Türkiye
No full text<title>Abstract</title> <p>Landslides are among the most frequent natural hazards that cause significant loss of life and serious economic damage worldwide. Although many inventories have been created using different approaches to understand landslide events, these are rarely updated automatically or in real time. Traditional approaches are laborious processes due to the time and intensive labor requirements, and are limited in terms of timeliness due to reporting delays. To address these challenges, we developed an automated approach that integrates web scraping, natural language processing (NLP), and geocoding techniques using digital media news sources in Türkiye to create a landslide archive inventory. Our algorithm verified 1727 of the 3051 news articles it captured between 1997 and 2024 as landslides and identified a total of 478 fatalities in 212 deadly incidents. 66.5% of the landslides captured on the web were located at the neighborhood/village level, providing substantial spatial accuracy. This location accuracy has also enabled risk estimation at the neighborhood/village level. Comparison with the manual national inventory shows moderate agreement, with F1 scores ranging from 0.434 to 0.552 in ± 1 and ± 7 daytime windows. The automated method not only captures spatial and temporal patterns of landslides but also extracts key attributes such as location, number of fatalities, and triggering factors (i.e., natural and anthropogenic). Our study demonstrates the potential of web-based automated approaches to complement traditional landslide inventories by providing near-real-time and verifiable data. Finally, we suggest adopting common reporting standards for natural hazard digital newspapers so that this approach can spread globally.</p>https://doi.org/10.21203/rs.3.rs-7463555/v
Improving rPET/PBT Bead Foam Structure via Chain Extender Modification and Blend Variance
No full textAbstract In this study, the influence of the chain extender (CE) and the blend ratio on the bead foam extrusion of rPET/PBT is investigated. The shape and density of the bead foams were analyzed during extrusion using a camera scanner while the morphology of the foam was investigated using scanning electron microscopy (SEM). Melt strength and thermal behavior were also investigated with Rheotens and differential scanning calorimetry (DSC), respectively. Both chain extender and blend ratio had pronounced effect on the foaming behavior. Significant improvements were observed up to 0.8 wt.-% CE in rPET50PBT50, which achieved an average cell size of 107 ± 17 μm and a density of 182 kg/m³, representing a weight reduction of 86.4% compared to the bulk material. In addition, rPET40PBT60 with 0.8 wt.-% CE gave an average cell size of 108 ± 23 μm and a foam density of 170 kg/m³, with a comparable cell size distribution. After CE modification, the melt strength of rPET-dominant blends obtained higher values but a strong decrease in elongation was observed. In contrast, the CE-modified rPET40PBT60 and rPET30PBT70 blends exhibited much higher elongation with a moderate increase in melt strength which resulted in better bead and foam morphologies. DSC analysis revealed lowest crystallization temperature in rPET50PBT50 with deviations shifting towards higher temperatures. All blends except rPET70PBT30 shows double melting peak formation, with higher rPET formulations also exhibiting cold crystallization. These findings provide crucial insight for development of rPET/PBT foams by controlling the blend and CE composition, which is critical for achieving temperature-resistant bead foams with improved structural integrity. Graphical Abstracthttps://doi.org/10.1007/s10924-024-03360-
Optimized Spirulina Fermentation with Lacticaseibacillus rhamnosus: Bioactive Properties and Pilot-Scale Validation
No full textSustainable bio-based products derived from fermentation are gaining increasing interest. The present study was designed to determine the interaction of Lacticaseibacillus rhamnosus 23.2 bacteria with spirulina in a 3 L glass bioreactor and the effect of aeration and agitation speed on the final product biomass and antioxidant capacity. The fermentation medium contained only glucose, an inorganic salt mixture, and spirulina powder. The estimated biomass and antioxidant activity were found to be 3.74 g/L and 84.72%, respectively, from the results of the optimization model. Scale-up was performed with the obtained optimization data, and three pilot-scale fermentations were carried out in a 30 L stainless steel bioreactor. As a result of pilot production, the obtained bioactive products were freeze-dried, and their antibacterial, antioxidant, total phenolic properties, and cytotoxic activity were investigated. The pilot production results showed that the increase in bacterial cell number was around 3–4 log after 24 h of fermentation. An inhibitory effect against pathogenic bacteria was observed. A strong radical scavenging effect was found in antioxidant analyses. Total phenolic substance content was 26.5 mg gallic acid equivalent (GAE) g−1, which was the highest level in this study. Cytotoxic activity showed that bioactive products had a cytotoxic effect against Caco-2 adenocarcinoma cells. This study emphasizes the potential of Arthrospira platensis biomass as a substrate for the production of lactic acid bacteria (LAB)-based bioproducts. It is thought that the results obtained from this study may position potential innovative strategies in the food, pharmaceutical, agriculture, and cosmetic industries.https://doi.org/10.3390/fermentation11050248https://doaj.org/article/9e9a4781f115426887dd03b544059e5chttps://avesis.yildiz.edu.tr/publication/details/3a5f6e1c-72a2-4c9f-b967-56e4d1a35e8c/oa
Metacognitive Awareness and Critical Thinking Disposition of Pre-Service Teachers: A Structural Equation Modeling
No full textMetacognition supports pre-service teachers' critical thinking (CT) processes because higher levels of metacognitive awareness of pre-service teachers increase their disposition to CT. This research aims to examine pre-service teachers' metacognitive awareness in terms of self-, organizational, and judgmental dimensions, to measure their CT disposition in engagement, cognitive maturity, and innovativeness, and to qualify the relationship between metacognitive awareness and disposition to CT of pre-service teachers. In the quantitatively designed study, the “Metacognitive Awareness Scale” and the adapted version of the “Critical Thinking Disposition Scale” were conducted on 305 pre-service teachers studying in the faculty of education in different universities in Turkiye. According to the results of descriptive analyses, the overall level of the pre-service teachers’ self-perceived metacognitive awareness was found high; the organizational awareness of the pre-service teachers was at the highest level whereas their level of judgmental awareness was the lowest, and the overall level of their self-perceived disposition to CT was calculated as high. The results of structural equation modeling analyses indicated that as the level of metacognitive awareness of pre-service teachers increases, their disposition to CT increases. Self- and organizational awareness exerted no significant influence on engagement, cognitive maturity, or innovativeness, while judgmental awareness had a significant positive effect on engagement but not on cognitive maturity or innovativeness.https://doi.org/10.16986/hunefd.170593
Optimization of Cross-Derivatives for Ribbon-Based Multi-Sided Surfaces
No full textThis work investigates ribbon-based multi-sided surfaces that satisfy positional and cross-derivative constraints to ensure smooth transitions with adjacent tensor-product and multi-sided surfaces. The influence of cross-derivatives, crucial to surface quality, is studied within Kato’s transfinite surface interpolation instead of control point-based methods. To enhance surface quality, the surface is optimized using cost functions based on curvature metrics. Specifically, a Gaussian curvature-based cost function is also proposed in this work. An automated optimization procedure is introduced to determine rotation angles of cross-derivatives around normals and their magnitudes along curves in Kato’s interpolation scheme. Experimental results using both primitive (e.g., spherical) and realistic examples highlight the effectiveness of the proposed approach in improving surface quality.https://doi.org/10.2139/ssrn.5097071https://doi.org/10.1016/j.gmod.2025.101275https://doaj.org/article/a6babe1e19a0413fbf2e05af4633e416https://avesis.yildiz.edu.tr/publication/details/c03d781d-011c-4786-954f-31703183ffbc/oa
A Novel Video-Based Approach for Dynamic Structural Identification of Iron Tie-Rods Under Adverse Environmental Conditions
No full texthttps://doi.org/10.1080/15583058.2025.256862
The relationship between sustainable finance and the CBAM: A policy impact assessment and hypothetical case study of a cement plan
No full textTez (Yüksek Lisans)-- İstanbul Teknik Üniversitesi, Lisansüstü Eğitim Enstitüsü, 2025Küresel iklim değişikliği, çevresel etkilerinin yanı sıra ekonomik, sosyal ve politik alanları da kapsayan yoğun gündemi ile 21. Yüzyılda tüm gerçekliği ile beraber yer almaktadır. İçinde bulunduğumuz 2025 senesi itibarı ile bireyler, şirketler, devletler ve uluslararası kuruluşlar gelecek stratejilerini oluştururken küresel iklim değişikliği gerçekliğine öncelik vermekte ve iklim krizi senaryoları ile hareket etmektedirler. Belirleyici rol oynayan ulusal ve uluslararası kuruluşlar tarafından iklim değişikliği ile mücadele ve iklim değişikliğine uyum süreçleri doğrultusunda iklim odaklı çalışmalar yürütülmekte ve sürdürülebilir kalkınma hedeflerini destekleyici politikalar uygulanmaktadır. Bu çalışmada, üçüncü taraf ülkesinde yer alan bir çimento üretim tesisinde Sınırda Karbon Düzenleme Mekanizması (SKDM)'nın sebep olacağı etkileri sürdürülebilir finans çerçevesinde çevresel ve ekonomik yönleriyle ele alarak Politika Etki Değerlendirmesi gerçekleştirilmiştir. SKDM, Avrupa Birliği (AB) tarafından geliştirilen, AB bölgesine ihraç edilen mallara karbon ücretlendirmesi uygulaması ile karbon sızıntısını önlemeyi amaçlayan bir mekanizmadır ve çimento sektörü SKDM kapsamında belirlenen en kritik altı karbon yoğun sektörden biridir. Yürütülen araştırmada çevresel ve finansal etkilerin değerlendirilmesi için varsayımsal bir vaka çalışması tasarımı kullanılmıştır. Hem nicel hem de nitel yöntemler kullanılan araştırmada, senaryo, finansal modelleme ve politika haritalaması gerçekleştirilmiştir. Temel performans göstergeleri arasında çevresel (CO₂ emisyonları, emisyon yoğunluğu), ekonomik (üretim ve uyumluluk maliyetleri, karlılık), teknolojik (yeşil teknolojiye geçiş) ve düzenleyici (GTİP Kodları, uyumluluk standartları) metriklere yer verilmiştir. Hipotez senaryolarında, üretim, maliyetler ve emisyon stratejileri üzerindeki etkileri değerlendirerek farklı SKDM uygulama seviyeleri modellenmiştir. Bu çalışmadaki finansal analiz, maliyet-fayda değerlendirmelerini içerirken; çevresel değerlendirme, emisyon azaltımlarını ve yeşil teknoloji verimliliğini içermektedir. Bu doğrultuda; varsayımsal yöntem ile Türkiye'de bulunan bir çimento üretim tesisinin üretim kapasitesi ve proses verileri belirlenmiştir. Belirlenmiş olan değerler ile çimento tesisinin Kapsam 1 ve Kapsam 2 emisyonlarının yanı sıra satın alınan klinker için Kapsam 3-Kategori 4 emisyonu da hesaplanmıştır. Tesisin mevcut durumdaki toplam sera gazı emisyonu değeri 1.398.350 tCO₂/yıl olarak hesaplanmış ve gömülü emisyon değerinin 0,55 tCO₂/ton çimento olduğu bilgisine ulaşılmıştır. SKDM Sertifika ücretlendirmesi hesaplanırken tesisin üretiminin %20'sinin, %40'ının ve %100'ünün AB bölgesine ihraç ettiği kabul edilerek üç farklı SKDM Beyanı ve buna bağlı olarak üç farklı SKDM Sertifika ücreti hesabı yapılmış ve ihracat oranına göre maliyet değişimi karşılaştırması yapılmıştır. Tesisin düşük karbonlu üretim stratejisi benimseyerek üretim sürecinde klinkeri azaltmasını sağlayan alternatif hammadde olarak Bentonit eklenerek Alternatif Hammadde Kullanım Senaryosu oluşturulmuştur. Alternatif Hammadde Kullanım Senaryosu sera gazı emisyon hesabında Mevcut Durum'dan farklılaşan kısım olan Kapsam 3 – Kategori 4 emisyonu hesabı yapılarak tesisin toplam sera gazı emisyonu değeri 1.310.724 tCO₂/yıl, gömülü emisyon değeri ise 0,52 tCO₂/ton çimento olarak hesaplanmıştır ve bu da alternatif hammadde kullanımının emisyon azaltımında etkili olduğunu göstermiştir. Alternatif Hammadde Kullanım Senaryosu'nda da SKDM Sertifika ücretlendirmesi hesaplanırken Mevcut Durum ile aynı yöntem izlenmiş ve üç farklı SKDM Beyanı ve buna bağlı olarak üç farklı SKDM Sertifika ücreti hesabı yapılarak ihracat oranına göre maliyet değişimi karşılaştırması yapılmıştır. Mevcut Durum ve Alternatif Hammadde Kullanım Senaryosu için toplam maliyet tutarları karşılaştırılarak finansal analiz tamamlanmıştır. Uluslararası boyutta iklim değişikliği ile mücadele faaliyetlerinin teşvik edilmesi amacı ile gelişen iklim politikaları değerlendirildiğinde, karbon yoğun sektörlerin mali yükümlülükler ile karşılaşacağını ancak emisyon azaltım teknolojilerini üretim süreçlerine entegre edilerek mali yükümlülüklerin azaltılabileceği öngörülmektedir. Özellikle Türkiye'nin iklim politikalarının uluslararası standartlar seviyesine gelmesi Türkiye'deki sektörlerin emisyon azaltım hedeflerine ulaşmalarını kolaylaştıracaktır.Yüksek Lisan