Istanbul Technical University
Ulusal Üniversitelerarası Açık Erişim Sistemi - İstanbul Teknik ÜniversitesiNot a member yet
67356 research outputs found
Sort by
Leadership Identity in Schools: A Qualitative Inquiry with School Administrators
No full textThis study aimed to explore how school administrators construct and interpret their professional identity through values, beliefs, knowledge, understandings, experiences, and wisdom. As a basic qualitative research design, the study exhibited the lived experiences of school administrators and how their leadership practices were shaped. A total of 13 school administrators, including principals and vice principals, working in schools at different educational levels, were selected through purposeful sampling to reflect maximum variation. The data were collected using semi-structured interviews. An abductive coding approach guided the analysis, which allowed the integration of emergent insights within the theoretical framework. The findings revealed five main themes that define professional identity: values and attitudes, beliefs, knowledge and skills, understandings, and experience and wisdom. Based on coded segments, subthemes were categorized under each theme. School administrators generally emphasized justice, democratic attitudes, experiential learning, situational awareness, and the role of personal and professional experiences as critical in their leadership identities. This research contributes to the literature on educational leadership by offering a deeper understanding of how school leaders make sense of their professional roles. The findings proved that professional identity is not static and is influenced by reflective practices, contextual awareness, and ongoing interactions between internal and external elements.https://doi.org/10.32960/uead.174912
Efficient Hardware Implementation of the Toom-Cook-4 Algorithm Using a Pipelined Architecture on FPGA
No full texthttps://doi.org/10.1109/isctrkiye68593.2025.1122485
Active Packaging Nanofiber Films Based on Polyvinyl Alcohol‐Pullulan With Probiotics to Improve the Shelf‐Life of Chicken Fillets
No full textABSTRACT The increasing demand for safe and longer‐lasting food products has attracted attention in the development of active and sustainable food packaging materials. In this study, polyvinyl alcohol (PVA) and pullulan (PULL) based electrospun nanofibers were used as nanocarriers for three probiotic strains– Lactobacillus acidophilus , Lactobacillus plantarum , and Lactobacillus rhamnosus – to develop an active food packaging material. Successful encapsulation of the probiotics into the PVA/PULL nanofiber structure was confirmed by scanning electron microscope, fourier transform infrared spectroscopy, and thermogravimetric analysis. The moisture content (MC) and thickness of the films were significantly increased with the incorporation of probiotics. However, no color change was observed with the incorporation of probiotics into the nanofibers . Lactobacillus plantarum and Lactobacillus rhamnosus incorporated nanofibers exhibited over 90% viability, which was considerably higher compared to the nanofibers of Lactobacillus acidophilus ( p < 0.05). The mechanical properties of the probiotic‐loaded films ranged from 5.24 ± 0.73 to 11.08 ± 2.31 MPa in tensile strength (TS), 38.2 ± 9.1 to 82.2 ± 8.9% in elongation at break (EAB), and 0.016–0.018 g·mm/m 2 ·h·kPa in water vapor permeability (WVP). Moreover, all nanofibers containing probiotics had antibacterial activity against Escherichia coli , Staphylococcus aureus , and Salmonella Typhimurium . Lactobacillus plantarum ‐incorporated nanofiber was selected for further testing with chicken fillets due to its superior viability, mechanical strength, and antimicrobial activity. The results demonstrated that Lactobacillus plantarum ‐incorporated nanofiber reduced lipid oxidation and microbial growth, extending the shelf life of chicken fillets. In conclusion, the probiotic‐incorporated PVA/PULL nanofibers present a promising approach for active food packaging applications.https://doi.org/10.1111/1750-3841.7046
Unifying thermodynamic and mechanical stability in perovskites: a computational approach for advanced applications
No full textPerovskite materials hold immense potential for advanced technologies, yet their practical deployment is hindered by an insufficient understanding of the interplay between thermodynamic and mechanical stability. This study bridges this critical gap by developing a unified computational framework that integrates both stability dimensions, enabling the rational design of perovskites for demanding applications. Leveraging pre-computed density functional theory data from The Materials Project and AFLOW databases, 44 perovskite materials are analyzed. Thermodynamic stability is assessed via formation energy and energy above hull, while mechanical stability is quantified through bulk modulus, shear modulus, and Pugh’s ratio. A novel combined stability index is introduced, employing geometric mean aggregation of normalized metrics to prioritize balanced performance. Key findings reveal that Ba-based perovskites exhibit superior thermodynamic stability and mechanical resilience. This work provides a computational blueprint for synthesizing perovskites tailored to applications requiring durability under thermal and mechanical stress, such as photovoltaics and catalysis. By correlating composition-structure-property relationships, the study advances the design of next-generation materials, emphasizing the necessity of holistic stability metrics.https://doi.org/10.55670/fpll.fusus.3.3.
Observation of the Charged-Particle Multiplicity Dependence of σψ(2S)/σJ/ψ in p -Pb Collisions at 8.16 TeV
No full textBound states of charm and anticharm quarks, known as charmonia, have a rich spectroscopic structure that can be used to probe the dynamics of hadron production in high-energy hadron collisions. Here, the cross section ratio of excited <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mo stretchy="false">(</a:mo><a:mrow><a:mi>ψ</a:mi><a:mo stretchy="false">(</a:mo><a:mrow><a:mn>2</a:mn><a:mi>S</a:mi></a:mrow><a:mo stretchy="false">)</a:mo></a:mrow><a:mo stretchy="false">)</a:mo></a:math> and ground state <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mo stretchy="false">(</g:mo><g:mrow><g:mi>J</g:mi><g:mo>/</g:mo><g:mi>ψ</g:mi></g:mrow><g:mo stretchy="false">)</g:mo></g:math> vector mesons is measured as a function of the charged-particle multiplicity in proton-lead (<k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mrow><k:mi>p</k:mi><k:mi>Pb</k:mi></k:mrow></k:math>) collisions at a center-of-mass (CM) energy per nucleon pair of 8.16 TeV. The data corresponding to an integrated luminosity of <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mn>175</m:mn><m:mtext> </m:mtext><m:mtext> </m:mtext><m:msup><m:mi>nb</m:mi><m:mrow><m:mo>−</m:mo><m:mn>1</m:mn></m:mrow></m:msup></m:math> were collected using the CMS detector. The ratio is measured separately for prompt and nonprompt charmonia in the transverse momentum range <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:mn>6.5</o:mn><o:mo>&lt;</o:mo><o:msub><o:mi>p</o:mi><o:mi mathvariant="normal">T</o:mi></o:msub><o:mo>&lt;</o:mo><o:mn>30</o:mn><o:mtext> </o:mtext><o:mtext> </o:mtext><o:mi>GeV</o:mi></o:math> and in four rapidity ranges spanning <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"><r:mo>−</r:mo><r:mn>2.865</r:mn><r:mo>&lt;</r:mo><r:msub><r:mi>y</r:mi><r:mi>CM</r:mi></r:msub><r:mo>&lt;</r:mo><r:mn>1.935</r:mn></r:math>. For the first time, a statistically significant multiplicity dependence of the prompt cross section ratio is observed in proton-nucleus collisions. There is no clear rapidity dependence in the ratio. The prompt measurements are compared with a theoretical model which includes interactions with nearby particles during the evolution of the system. These results provide additional constraints on hadronization models of heavy quarks in nuclear collisions.https://doi.org/10.1103/c9wp-5tq
Polyester/clay nanocomposite synthesis via metal-free azide-alkyne click reaction
No full texthttps://doi.org/10.1080/10601325.2025.258182
Investigation of building fire safety measures in building information modelling (BIM) environment
No full textIn parallel with the advancement of building technology, Building Information Modelling (BIM) has gained prominence among stakeholders in the design and construction industries. BIM is becoming an increasingly effective tool in the field of fire safety, as it is in most design disciplines. In this study, an office building was modelled with Revit, one of the most extensively used BIM software, and its fire safety features were investigated utilising CYPEFIRE Design and FINEFIRE software operating in the BIM environment. The fire safety requirements of the office building are governed by the regulations outlined in Turkey’s Fire Protection Regulation and the pertinent standards. By the standards outlined in EN ISO 9241-11, a usability assessment was conducted to evaluate the dimensions of learnability, efficiency, memorability, errors, and satisfaction. The assessments revealed that the CYPEFIRE Design software provided 13 (52%) and the FINEFIRE software 10 (40%) compliance checks by the regulations and standards about the building’s 25 fire safety measures. In terms of usability parameters, the CYPEFIRE Design software is rated first for efficiency and error assessment, while the FINEFIRE software is rated first for learnability and memorability. The two software programs are distinct from one another and offer particular advantages in specific areas. The decisions made based on the data obtained from this software can examine the influence of fire safety measures on the entire structure and facilitate more effective management of the fire safety design process. In light of the prevailing circumstances, it seems inevitable that Building Information Modelling (BIM) technology will become more prevalent and comprehensive in the field of fire safety shortly.https://doi.org/10.1177/1478077125132309
Lazer Kesme Hızının Tungsten Karbür Malzemede Kesme Derinliği Üzerine Olan Etkisi
No full textTalaşlı imalat malzemelere uygulanan en yaygın imalat yöntemlerinden biridir. Talaşlı imalatta talaş kaldırma işlemi genellikle bir kesici uç vasıtasıyla gerçekleştirilmektedir. Kesici uçlar, işlenen malzemeden kayma deformasyonu ile malzeme kaldırarak yeni bir yüzey oluştururlar. Bu işlem neticesinde kesici uç zamanla aşınır ve kullanılamaz hale gelir. Kesici uç performansının iyileştirilmesi ve kesici takım ömrünün artırılması ile ilgili çalışmalar son yıllarda lazer ışınları ile tekstür oluşturma üzerine yoğunlaştırılmıştır. Yüzeylere lazer ışınları ile tekstür açma işlemlerinde malzemeye çeşitli gravürler açılarak bu gravürlerin bir desen oluşturması ve malzemelerin tribolojik özelliklerini iyileştirmesi beklenmektedir. Yüzeylerde lazer ışınları ile tekstür oluşturma işlemlerinin mekanizmasının anlaşılabilmesi için lazer ile işleme parametrelerinin malzeme üzerinde bıraktığı etkilerin irdelenmesi gerekmektedir. Bu çalışmada da, en çok kullanılan kesici uç malzemelerinden biri olan tungsten karbür malzemenin üzerine farklı lazer kesme hızları ile gravürler açılmış ve lazer kesme hızı ile kesme derinliği arasındaki ilişki gözlemlenmiştir.https://doi.org/10.56193/matim.164679
Seismic Anisotropy Variations in the Eastern Mediterranean Sea Region Revealed by Splitting Intensity Tomography: Implications on Mantle Dynamics
No full textAbstractReliable knowledge of seismic anisotropy in the mantle can provide invaluable insights into complex tectonics and geodynamics in Anatolia controlled by intricate plate interactions across the region. However, the 3D variations in seismic anisotropy within the crust and upper mantle beneath this area remain poorly constrained. In the present study, we performed splitting intensity (SI) tomography technique, using over 25,000 SI measurements from SKS/SKKS waves recorded at 690 seismic stations, to map lateral and vertical variation of anisotropy that is essential for accurate geodynamic interpretations for Eastern Mediterranean. Our tomographic images show large‐scale mantle flow at asthenospheric depths, oriented in east‐west and northeast‐southwest directions. This flow pattern can be attributed to basal drag forces, which play an important role in driving the westward motion of the Anatolian plate. The strong azimuthal anisotropy in the back‐arc region of the Hellenic subduction zone, with trench‐perpendicular orientation, highlights the significant impact of trench retreat and rollback of the African lithosphere on deformations in the mantle lithosphere and asthenosphere beneath the Aegean region and western Türkiye. The observed weak azimuthal anisotropy, on the other hand, is largely identified across various depths beneath Quaternary volcanoes in the Central and East Anatolian Volcanic Provinces and along the Cyprus subducting slab in the upper mantle. Our numerical tests prove that these weak anomalies may result from plunging/vertical anisotropy associated with upwelling and/or downwelling mantle in central and eastern Anatolia.https://doi.org/10.1029/2024jb03033
Quantization of Carrollian fermions
No full textWe provide the first example of interacting quantized Carrollian Dirac fermions in four dimensions and investigate their discrete symmetries, including charge conjugation (<a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mi>C</a:mi></a:mrow></a:math>), parity (<c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>P</c:mi></c:math>), and time reversal (<e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mi>T</e:mi></e:math>) transformations. As a toy model, we couple these fermions to a Carrollian scalar field using Carrollian Yukawa theory and compute the tree-level diagram, revealing an ultralocal interaction between the Carrollian fermions and the scalar field. This interaction, widely known as a Dirac delta interaction with time-dependent factor, frequently appears in quantum physics. We then address the renormalization of the theory by employing the Wilsonian procedure at one-loop order. Furthermore, we analyze the fixed points and stability properties of Carrollian Yukawa theory, comparing them with their relativistic counterparts. Beyond the specific Yukawa model studied here, we expect that our framework will have broader applications in Carrollian physics, particularly in understanding ultralocal interactions and their role in condensed matter systems, where similar phenomena arise in strongly correlated and nonrelativistic regimes.https://doi.org/10.1103/physrevd.111.105019https://dx.doi.org/10.48550/arxiv.2502.05645http://arxiv.org/abs/2502.05645https://hdl.handle.net/20.500.12831/2649