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Search for Dark Matter Produced in Association With a Pair of Bottom Quarks in Proton-Proton Collisions at √s=13 TeV
No full textA search for dark matter (DM) particles produced in association with bottom quarks is presented. The analysis uses proton-proton collision data at a center-of-mass energy of s = 13 TeV, corresponding to an integrated luminosity of 138 fb−1. The search is performed in a final state with large missing transverse momentum and a pair of jets originating from bottom quarks. No significant excess of data is observed with respect to the standard model expectation. Results are interpreted in the context of a type-II two-Higgs-doublet model with an additional light pseudoscalar (2HDM+a). An upper limit is set on the mass of the lighter pseudoscalar, probing masses up to 260 GeV at 95% confidence level. Sensitivity to the parameter space with the ratio of the vacuum expectation values of the two Higgs doublets, tan β, greater than 15 is achieved, capitalizing on the enhancement of couplings between pseudoscalars and bottom quarks with high tan β. © The Author(s) 2025.Ministry of Education and Science, MES; Benemérita Universidad Autónoma de Puebla, BUAP; Center for African Studies, CAS; Fundação para a Ciência e a Tecnologia, FCT; Department of Atomic Energy, Government of India, DAE; PCTI; National Academy of Sciences of Ukraine, NASU; National Science and Technology Development Agency, NSTDA; Fundamental Research Funds for the Central Universities; MSES; Ministry of Education of the People's Republic of China, MOE; National Science Foundation, NSF; Missouri University of Science and Technology, MST; Institut National de Physique Nucléaire et de Physique des Particules, IN2P3; Science and Technology Facilities Council, STFC; F.R.S.-FNRS; Council of Science and Industrial Research; Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, CINVESTAV; Ministério da Educação e Ciência, MEC; MEYS; Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, FAPERJ; Ministerio de Ciencia e Innovación, MCIN; Universiti Malaya, UM; Bundesministerium für Bildung, Wissenschaft und Forschung, BMBWF; FAIR; National Science Council, NSC; Ministry of Science,Technology and Research, MoSTR; Hispanics in Philanthropy, HIP; Hungarian Academy of Sciences; Secretaría de Educación Pública, SEP; Austrian Science Fund, FFWF; Department of Science and Technology, Ministry of Science and Technology, India, IndiaDST; Chulalongkorn Academic; Consejo Nacional de Humanidades, Ciencias y Tecnologías; ERDF; Centre National de la Recherche Scientifique, CNRS; Bundesministerium für Bildung und Forschung, BMBF; Fonds Wetenschappelijk Onderzoek, FWO; Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TUBITAK; LMTLT; Research Council of Finland, AKA; Conselho Nacional de Desenvolvimento Científico e Tecnológico, CNPq; Pakistan Atomic Energy Commission, PAEC; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, CAPES; California Earthquake Authority, CEA; Türkiye Enerji, Nükleer ve Maden Araştırma Kurumu, TENMAK; Nvidia Corporation; Hellenic Foundation for Research and Innovation; Belgian Federal Science Policy Office; Deutsche Forschungsgemeinschaft, DFG; LNS; Alfred P. Sloan Foundation; Ministarstvo Prosvete, Nauke i Tehnološkog Razvoja, MPNTR; Fonds pour la Formation à la Recherche dans l’Industrie et dans l’Agriculture; Science Foundation Ireland, SFI; U.S. Department of Energy, FEA; Fundação de Amparo à Pesquisa do Estado de São Paulo, FAPESP; Cosmetic Surgery Foundation, CSF; Agencia Estatal de Investigación, AEI; ICSC; FRIA-Belgium; Ministry of Education, Youth and Sports; Ministry of Science and Technology of the People's Republic of China, MOST; Programa Severo Ochoa del Principado de Asturias; General Secretariat for Research and Innovation, GSRI; Bulgarian National Science Fund, BNSF; Latvian Council of Science; Hugh Green Foundation, HGF; Ministerio de Ciencia, Tecnología e Innovación; Maryland Ornithological Society, MOS; Ministry of Higher Education, Science, Research and Innovation, Thailand, MHESI; Fonds De La Recherche Scientifique - FNRS, FNRS; Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, FAPERGS; Shota Rustaveli National Science Foundation, SRNSF; Institute for Research in Fundamental Sciences, IPM; Leventis Foundation; Swiss Funding Agencies; European Research Council; CERN, CERN; National Retail Federation, NRF; Ministry of Science ICT and Future Planning, MSIP; Secretaría de Educación Superior, Ciencia, Tecnología e Innovación, SENESCYT; Ministry for Business Innovation and Employment, MBIE; Istituto Nazionale di Fisica Nucleare, INFN; Weston Havens Foundation; Universidad Autónoma de San Luis Potosí, UASLP; National Natural Science Foundation of China, NNSFC; Kavli Foundation; Qatar National Research Fund, (MCIN/AEI/10.13039/501100011033); Alexander von Humboldt Foundation, (22rl-037); Beijing Municipal Science ; Technology Commission, (Z191100007219010); Deutsche Forschungsgemeinschaft, (400140256 — GRK2497, 390833306); Shota Rustaveli National Science Foundation, (FR-22-985); National Science Center, (2021/43/B/ST2/01552, 2021/41/B/ST2/01369); COST, (CA16108); Horizon 2020, (101115353, 765710, 752730, 724704, 758316, 824093, 675440, 101002207); Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, (MDM-2017-0765); Ministry of Education and Science, (2022/WK/14); Welch Foundation, (C-1845); National Science, Research and Innovation Fund, (B39G670016); Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, NKFIH, (K 138136, K 143477, K 143460, K 146914, 2020-2.2.1-ED-2021-00181, K 131991, K 133046, K 146913, K 147048, TKP2021-NKTA-64); Nemzeti Kutatási Fejlesztési és Innovációs Hivatal, NKFIH; Fundação para a Ciência e a Tecnologia, (CEECIND/01334/2018); Engineering Research Centers, ERC, (MoER TK202); Engineering Research Centers, ERC; Excellence of Science, (30820817
Dual- and Triple- Hetero-Atom Carbon Dots as Novel Additives for the Engineering of Defects Passivation To Boost Performance of Perovskite Solar Cells
No full textMethylammonium lead iodide (MAPbI3)-based perovskite solar cells (PSCs) offer highly efficient photovoltaics. However, several disadvantages such as poor stability and possibility of defect formation reducing film quality have restricted its commercialization. In this work, we reported the synthesis of dual- and triple-hetero-atom-doped carbon quantum dots (CQDs) via hydrothermal method and their effect of use as additive on the performance of PSCs. The boron (B) and phosphorous (P)-doped CQDs (B,P-CQDs), sulphur (S) and P-doped CQDs (S,P-CQDs), and B, S, and P-doped CQDs (B,S,P-CQDs) additives were described. Since these CQDs have many functional groups including hydroxyl (-OH), they can easily interact with Pb ions leading to the formation of PbO, as well as interaction with methyl ammonium ions. A reduced halide vacancy density and an increased nucleation energy of perovskite enhance crystal sizes and charge transfer. The passivation of surface defects reduces non-radiative recombination and ion migration, which plays an important role in photodegradation of the MAPbI3 films. Herein, the introduction of S,P-CQDs improved power conversion efficiency (PCE) from 10 to 15% and current density (Jsc) from 14.4 to 23.6 mA cm-2. PSCs added with dual- and triple-hetero-atom-doped CQDs showed narrower efficiency distribution in comparison to the control devices.Open access funding provided by the Scientific and Technological Research Council of Turkiye (TUB ; Idot;TAK). This study was funded by Turkiye Bilimsel ve Teknolojik Ara ; scedil;t ; imath;rma Kurumu, (Grant Number: 121F377), Cisem K ; imath;rb ; imath;y ; imath;k Kurukavak.Scientific and Technological Research Council of Turkiye (TUBIdot;TAK); Turkiye Bilimsel ve Teknolojik Arascedil;timath;rma Kurumu [121F377
Influence of Overhang Length on Ltb Behavior of Compact Doubly-Symmetric Steel I-Beams
No full textThe present study pertains to elaborating on the effects of overhang lengths beyond end supports on elastic and inelastic Lateral Torsional Buckling behaviour of doubly-symmetric steel I-beams. Finite element analyses were performed on compact sections to avoid the local (plate) buckling and beam distortions to interfere with the overall beam behaviour. Accuracy of the numerical analyses was verified with the help of existing experimental results. Subsequent to this verification, 120 beams with five different compact I-sections, four different overhang lengths, two different unbraced span lengths and three different sweep values were analysed. The numerical buckling moments of the beams with considerable overhangs were established to remain well below the respective estimates from AISC 360-16 formulation. The difference between the numerical and analytical values stems from the inability of the formula to reflect the lateral deflections of overhangs, i.e. predicating on full lateral restraint beyond unbraced spans. The study also indicated that flexural rigidities and moment capacities of beams increase with increasing overhang lengths. The increase in the buckling moment resistance in elastic and inelastic LTB were established to reach 11 and 16%, as the overhang-to-total length ratio increases from 0 to 0.30 for various sweep values. © 2025 Informa UK Limited, trading as Taylor ; Francis Group
Novel Smart Materials With High Curie Temperatures: Eusub>1.90/Sub> Dysub>0.10/Sub>gesub>2 , Eusub>1.90/Sub> Lasub>0.10/Sub>gesub>2 and Eusub>1.90/Sub> Hosub>0.10/Sub> Gesub>2/Sub> Osub>7/Sub>
No full textThe Eu-1.90 Dy0.10Ge2O7 , Eu-1.90 La0.10Ge2O7 and Eu-1.90 Ho-0.10 Ge-2 O-7 powder were obtained through a solid-state reaction method via multistep firing of stoichiometric ratios of Eu2O3, GeO2, Dy2O3, La2O3 and Ho2O3 in open atmosphere at temperatures from 800 to 1150 degrees C. The thermal behaviour, phase formation, SEM/EDX analysis, photoluminescence properties, Curie tempereture, dielectric and piezoelectric properties of the samples were investigated by TG/DTA, XRD, SEM, PL, TG/DTA, LCR-meter and d33-meter, respectively. The germenates having triclinic crystal system have D-5(0)-> F-7(4), D-5(0)-> F-7(3), D-5(0 )-> F-7(2), 5D0 -> 7F1 transitions of Eu(3+)ions. Also, the photoluminescent germenates show electrical properties and the piezoelectric charge constant of germenates showed Eu1.90Dy0.10Ge2O7>Eu1.90Dy0.10Ge2O7 >Eu1.90La0.10Ge2O7 trend. The Curie temperature of Eu1.90Dy0.10Ge2O7, Eu1.90Dy0.10Ge2O7 and Eu1.90Dy0.10Ge2O7 are 825, 844 and 838 degrees C, respectively. Compared to commonly used piezoelectric materials, Eu1.90Dy0.10Ge2O7, Eu1.90Dy0.10Ge2O7 and Eu1.90Dy0.10Ge2O7 materials with very high Curie temperatures were obtained with photoluminescent properties.This project was supported by The Scientific and Technological Research Council of Turkey (TUBITAK, project number 114Z438) . The authors would like to thank to TUBITAK. This study was conducted at Department of Metallurgical and Materials Engineering, Faculty of Engineering, Karamanoglu Mehmetbey University.Scientific and Technological Research Council of Turkey (TUBITAK) [114Z438
Search for a Heavy Resonance Decaying into a Z and a Higgs Boson in Events with an Energetic Jet and Two Electrons, Two Muons, or Missing Transverse Momentum in Proton-Proton Collisions at S = 13 TeV
No full textA search is presented for a heavy resonance decaying into a Z boson and a Higgs (H) boson. The analysis is based on data from proton-proton collisions at a centre-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb−1, recorded with the CMS experiment in the years 2016–2018. Resonance masses between 1.4 and 5 TeV are considered, resulting in large transverse momenta of the Z and H bosons. Final states that result from Z boson decays to pairs of electrons, muons, or neutrinos are considered. The H boson is reconstructed as a single large-radius jet, recoiling against the Z boson. Machine-learning flavour-tagging techniques are employed to identify decays of a Lorentz-boosted H boson into pairs of charm or bottom quarks, or into four quarks via the intermediate H → WW* and ZZ* decays. The analysis targets H boson decays that were not generally included in previous searches using the H → bb¯ channel. Compared with previous analyses, the sensitivity for high resonance masses is improved significantly in the channel where at most one b quark is tagged. © 2025 Elsevier B.V., All rights reserved
Optimization of Mechanical Properties of Geopolymer Mortar Based on Class C Fly Ash and Silica Fume: a Taguchi Method Approach
No full textThis study examines the mechanical properties of Class C fly ash-based geopolymer mortar to optimize its use. Using Taguchi's experimental design methodology, compressive and flexural strength tests were conducted to determine the ideal mix ratios. An L16 orthogonal array with five factors and four levels was used to assess the effects of sodium hydroxide concentration (10, 12, 14, and 16 M), alkaline solution-to-binder ratio, sodium silicate to sodium hydroxide ratio, water to geopolymer solids ratio, and aggregate percentage. Samples were cured at room temperature for 28 days. Results showed that the highest compressive strength (20.52 MPa) was achieved with alkaline solution-to-binder ratio = 0.3, water-to-geopolymer solids ratio = 0.35, sodium silicate-to sodium hydroxide ratio = 1.75, and aggregate percentage = 0.60, while the lowest (2.64 MPa) occurred with alkaline solution-to-binder ratio = 0.3, water to geopolymer solids ratio = 0.55, sodium silicate to sodium hydroxide ratio = 2.5, and aggregate percentage = 0.65. Similarly, the highest flexural strength (4.69 MPa) was noted with alkaline solution-to- binder ratio = 0.3, water-to-geopolymer solids ratio = 0.35, sodium silicate to sodium hydroxide ratio = 1.75, and aggregate percentage = 0.60, and the lowest (0.57 MPa) with alkaline solution-to-binder ratio = 0.3, water to geopolymer solids ratio = 0.55, sodium silicate to sodium hydroxide ratio = 2.5, and aggregate percentage = 0.65. The optimal parameters for maximum compressive strength were water-to-geopolymer solids ratio = 0.35, molarity = 10 M, alkaline solution-to-binder ratio = 0.40, sodium silicate to sodium hydroxide ratio = 2.0, and aggregate percentage = 0.70. For flexural strength, the optimal levels were water to geopolymer solids ratio = 0.35, molarity = 10 M, alkaline solution-to-binder ratio = 0.40, sodium silicate to sodium hydroxide ratio = 1.75, and aggregate percentage = 0.70.This research is supported by the Faculty of Engineering, Konya Technical University. The authors would like to express their gratitude to the Scientific Research Project Coordinator (BAP) for award No. 211104034.Faculty of Engineering, Konya Technical University; Scientific Research Project Coordinator (BAP) [211104034
Removal of Hexavalent Chromium From Aqueous Solutions Using Nano-fe3o4/Waste Banana Peel/Alginate Hydrogel Biobeads as Adsorbent
No full textIn this study, the removal of Cr(VI), known as one of the most dangerous heavy metal pollutants, was investigated by adsorption method using magnetic alginate biopolymer-supported banana peel composite beads (MAB), which were synthesized for the first time. Using plant waste for this composite synthesis is both important in terms of utilization of plant waste and more environmentally friendly. Optimum conditions were determined by examining the parameters of concentration (10–300 ppm), adsorbent dose (1–8 g/L), mixing time (5–360 min), pH (2–8), and temperature (25–55 °C). Characterization of this new synthesized composite adsorbent, FTIR, XRD, SEM, and EDX mapping measurements were performed. The experimentally found adsorption data were modeled by applying Freundlich, Langmuir, Scharthard, Temkin, and D-R isotherm models, and isotherm constants were calculated. The adsorption data on MAB are more compatible with the Langmuir and Freundlich isotherm. In the shaking-batch system at 25 °C and pH = 2, the maximum adsorption capacity of the composite was calculated as 370.4 mg/g. Adsorption kinetics were found to be suitable for pseudo-second-order. Thermodynamic studies were realized to evaluate thermal changes of the adsorption process, and desorption processes were realized to determine the regeneration times of MAB. The temperature studies showed that adsorption capacity increased with increasing temperature, showing that the system was endothermic. As a result, it has been shown that MAB can be used as an efficient biocomposite adsorbent for the removal and recovery of Cr (VI) ions from aqueous media. © The Author(s) 2025.Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK; Konya Teknik Üniversitesi, KTÜN, (231016053
Observation of Nuclear Modification of Energy-Energy Correlators Inside Jets in Heavy Ion Collisions
No full textKirschenmann, Henning/0000-0001-7369-2536; D'Anzi, Brunella/0000-0002-9361-3142; Chatterjee, Suman/0000-0003-2660-0349; Martikainen, Laura/0000-0003-1609-3515; Grosso, Gaia/0000-0002-8303-3291; Giacomelli, Paolo/0000-0002-6368-7220; Lampen, Tapio/0000-0002-8398-4249; Smith, Nicholas/0000-0002-0324-3054; Wilson, Graham/0000-0003-0917-4763; Pasztor, Gabriella/0000-0003-0707-9762; Hall, Geoffrey/0000-0002-6299-8385; Mitra, Soureek/0000-0002-3060-2278; Vannerom, David/0000-0002-2747-5095; Linden, Tomas/0009-0002-4847-8882; Yazgan, Efe/0000-0001-5732-7950; Pesaresi, Mark/0000-0002-9759-1083; Forthomme, Laurent/0000-0002-3302-336X; Kyberd, Paul/0000-0002-7353-7090; Rantanen, Milla-Maarit/0000-0002-6764-0016; Csanad, Mate/0000-0002-3154-6925; Barroso Ferreira, Mapse/0000-0003-3904-0571; Tapper, Alexander/0000-0003-4543-864X; Zhang, Yousen/0000-0002-6812-761X; Viinikainen, Jussi/0000-0003-2530-4265; Luukka, Panja/0000-0003-2340-4641; Garcia, Francisco/0000-0002-4023-7964; Grandi, Claudio/0000-0001-5998-3070Energy-energy correlators are constructed by averaging the number of charged particle pairs within jets, weighted by the product of their transverse momenta, as a function of the angular separation of the particles within a pair. They are sensitive to a multitude of perturbative and nonperturbative quantum chromodynamics phenomena in high-energy particle collisions. Using lead-lead data recorded with the CMS detector, energy-energy correlators inside high transverse momentum jets are measured in heavy ion collisions for the first time. The data are obtained at a nucleon-nucleon center-of-mass energy of 5.02TeV and correspond to an integrated luminosity of 1.70 nb(-1). A similar analysis is done for proton-proton collisions at the same center-of-mass energy to establish a reference. The ratio of lead-lead to proton-proton energy-energy correlators reveals significant jet substructure modifications in the quark-gluon plasma. The results are compared to different models that incorporate either color coherence or medium response effects, where the two effects predict similar substructure modifications.Individuals have received support from the Marie-Curie program and the European Research Council and Horizon 2020 Grant, contract Nos. 675440, 724704, 752730, 758316, 765710, 824093, 101115353, 101002207, and COST Action CA16108 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexander von Humboldt Foundation; the Science Committee, project no. 22rl-037 (Armenia); the Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Beijing Municipal Science ; Technology Commission, No. Z191100007219010 and Fundamental Research Funds for the Central Universities (China); The Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Shota Rustaveli National Science Foundation, grant FR-22-985 (Georgia); the Deutsche Forschungsgemeinschaft (DFG), among others, under Germany's Excellence Strategy - EXC 2121 "Quantum Universe'' - 390833306, and under project number 400140256 - GRK2497; the Hellenic Foundation for Research and Innovation (HFRI), Project Number 2288 (Greece); the Hungarian Academy of Sciences, the New National Excellence Program - UNKP, the NKFIH research grants K 131991, K 133046, K 138136, K 143460, K 143477, K 146913, K 146914, K 147048, 2020-2.2.1-ED2021-00181, TKP2021-NKTA-64, and 2021-4.1.2-NEMZ_KI-2024-00036 (Hungary); the Council of Science and Industrial Research, India; ICSC - National Research Center for High Performance Computing, Big Data and Quantum Computing and FAIR - Future Artificial Intelligence Research, funded by the NextGenerationEU program (Italy); the Latvian Council of Science; the Ministry of Education and Science, project no. 2022/WK/14, and the National Science Center, contracts Opus 2021/41/B/ST2/01369 and 2021/43/B/ST2/01552 (Poland); the Fundacao para a Ciencia e a Tecnologia, grant CEECIND/01334/2018 (Portugal); the National Priorities Research Program by Qatar National Research Fund; MICIU/AEI/10.13039/501100011033, ERDF/EU, "European Union NextGenerationEU/PRTR'', and Programa Severo Ochoa del Principado de Asturias (Spain); the Chulalongkorn Academic into Its 2nd Century Project Advancement Project, and the National Science, Research and Innovation Fund via the Program Management Unit for Human Resources ; Institutional Development, Research and Innovation, grant B39G670016 (Thailand); the Kavli Foundation; the Nvidia Corporation; the SuperMicro Corporation; the Welch Foundation, contract C-1845; and the Weston Havens Foundation (USA).Marie-Curie program; European Research Council; Horizon 2020 Grant [675440, 724704, 752730, 758316, 765710, 824093, 101115353, 101002207]; COST Action [CA16108]; Leventis Foundation; Alfred P. Sloan Foundation; Alexander von Humboldt Foundation; Science Committee [22rl-037]; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); Beijing Municipal Science ; Technology Commission [Z191100007219010]; Fundamental Research Funds for the Central Universities (China); Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; Shota Rustaveli National Science Foundation [FR-22-985]; Deutsche Forschungsgemeinschaft (DFG) [EXC 2121, 390833306, 400140256 - GRK2497]; Hellenic Foundation for Research and Innovation (HFRI) [2288]; Hungarian Academy of Sciences [K 131991, K 133046, K 138136, K 143460, K 143477, K 146913, K 146914, K 147048, 2020-2.2.1-ED2021-00181, TKP2021-NKTA-64, 2021-4.1.2-NEMZ_KI-2024-00036]; Council of Science and Industrial Research, India - NextGenerationEU program (Italy); Latvian Council of Science; Ministry of Education and Science [2022/WK/14]; National Science Center [Opus 2021/41/B/ST2/01369, 2021/43/B/ST2/01552]; Fundacao para a Ciencia e a Tecnologia [CEECIND/01334/2018]; National Priorities Research Program by Qatar National Research Fund [MICIU/AEI/10.13039/501100011033]; ERDF/EU; Programa Severo Ochoa del Principado de Asturias (Spain); National Science, Research and Innovation Fund via the Program Management Unit for Human Resources ; Institutional Development, Research and Innovation [B39G670016]; Kavli Foundation; Nvidia Corporation; SuperMicro Corporation; Welch Foundation [C-1845]; Weston Havens Foundation (USA
From Raw to Fermented: Uncovering the Microbial Wealth of Dairy
No full textDairy products harbor complex and dynamic microbial communities that contribute to their sensory properties, safety, and cultural distinctiveness. Raw milk contains a diverse microbiota shaped by seasonality, storage conditions, lactation stage, animal health, farm management, and genetics, serving as a variable starting point for further processing. Fermentation, whether spontaneous or starter driven, selects for subsets of lactic acid bacteria (LAB), yeasts, and molds, resulting in microbial succession that underpins both artisanal and industrial products such as kefir and cheese. Kefir represents a balanced LAB-yeast symbiosis, with species composition influenced by grain origin, milk type, and processing parameters, whereas the cheese microbiota reflects the interplay of starter and non-starter LAB, coagulants, ripening conditions, and "house microbiota". Methodological factors-including DNA extraction, sequencing platform, and bioinformatic pipelines-further impact the reported microbial profiles, highlighting the need for standardization across studies. This review synthesizes current knowledge on raw milk, kefir, and cheese microbiomes, emphasizing the biological, technological, environmental, and methodological factors shaping microbial diversity. A holistic understanding of these drivers is essential to preserve product authenticity, ensure safety, and harness microbial resources for innovation in dairy biotechnology
Investigation of the Structural Strength of a Carbon Fiber Reinforced Spar in an UAV Wing Based on Cross-Section Profile and Ply Orientations Using the Finite Element Method
No full textDue to their high strength, low density, and fatigue resistance, carbon fiber reinforced composites are widely used in the aerospace industry. The use of these materials is increasing day by day, particularly in the wing and fuselage structures of lightweight aerial platforms. Numerous studies can be found in the literature on this topic. In this thesis, the structural behavior of carbon fiber reinforced composite beams used in wing structures which is one of the most critical components of air vehicles has been numerically investigated with respect to cross-sectional profiles and fiber lay-up angles. Within this scope, finite element models were developed for beam structures with I, C, and box cross-sections, using fiber orientations of 0˚ and ±45˚, under aerodynamic loading conditions. A wing design was created for a selected aircraft configuration, and the pressure loads obtained from CFD (Computational Fluid Dynamics) analyses conducted on this wing were transferred to the structural model using a one-way Fluid-Structure Interaction approach. Based on these loads, static structural analyses were performed. The results were then evaluated in relation to the cross-sectional profiles and lay-up angles of the beams. It was observed that the use of ±45˚ fiber layers led to sudden drops in IRF (Inverse Reserve Factor) values, whereas 0˚ fibers resulted in increased IRF values with noticeable fluctuations. These fluctuations became more pronounced as the ratio of ±45˚ layers in the stacking sequence increased. On the other hand, lay-ups consisting completely 0˚ fibers showed a highly consistent IRF distribution. Moreover, the use of ±45˚ layers was found to increase deformations in both the lift and drag directions. In terms of cross-section comparison, the box profile demonstrated superior strength, while the C profile proved more advantageous in terms of weight. Although the I profile was close to the C profile in terms of weight, it lagged behind both in strength and in terms of manufacturing complexity.Yüksek dayanım, düşük yoğunluk, yorulma dayanımı gibi avantajları dolayısıyla karbonfiber takviyeli kompozitler havacılık ve uzay sektöründe yaygın olarak kullanılmaktadır. Özellikle hafif hava platformlarının kanat ve gövde yapılarında da karbonfiber takviyeli kompozit malzemelerin kullanımı günden güne artmaktadır. Bu konuda literatürde çeşitli çalışmalar mevcuttur. Bu tez çalışmasında, hava araçlarının kritik bileşenlerinden biri olan kanat yapılarında kullanılan karbonfiber takviyeli kompozit kirişlerin kesit profillerine ve fiber serim açılarına bağlı yapısal davranışları numerik olarak incelenmiştir. Bu bağlamda, I, C ve kutu profillere sahip kiriş yapılarının 0˚, ±45˚ fiber kombinasyonlarında, aerodinamik yüklemeler altında sonlu elemanlar modeli oluşturulmuştur. Belirlenen hava aracı konfigürasyonu için bir kanat tasarımı yapılmış, bu kanat tasarımı üzerinde gerçekleştirilen HAD (Hesaplamalı Akışkanlar Dinamiği) analizleri sonucunda elde edilen basınç yükleri, tek yönlü Akışkan-Yapı etkileşimi yöntemi ile yapısal modele aktarılarak kanat yapılarının statik analizleri gerçekleştirilmiştir. Çıkan sonuçlara göre kirişlerin yapısal davranışları kesit profiline ve serim açılarına bağlı olarak değerlendirilmiştir. Bulunan sonuçlarda ±45˚ fiber kullanımında IRF (Ters Emniyet Katsayısı) değerlerinde ani düşüşler görülse de 0° fiberlerde IRF değerlerinin arttığı ve dalgalanmalar olduğu gözlemlenmiştir. Bu dalgalanmalar ±45˚ fiberlerin tüm katmanlara oranı arttıkça artmaktadır. Sadece 0° fiberlerin kullanıldığı oryantasyonlarda ise oldukça düzenli bir IRF dağılımı olduğu gözlemlenmiştir. Ayrıca ±45˚ fiber kullanımının taşıma ve sürükleme yönlerinde deformasyonları da arttırdığı görülmüştür. Profil kesitlerinin karşılaştırmasında ise kutu profil dayanımsal olarak öne çıkarken C profil ağırlık bakımından daha avantajlıdır. I profil ise ağırlık bakımından C profile yakın olsa da hem dayanım hem de üretim zorluğu açısından diğer profillerin gerisinde kalmıştır