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Nanoarchitectonics and radiation mitigation in Sm2O3-doped lithium borotellurite glass systems: from amorphous harmony to localized order
No full textIn this study, a novel series of nano-Sm2O3-doped lithium borotellurite glasses was synthesized and systematically investigated in terms of their structural, physical, and radiation shielding characteristics. X-ray diffraction confirmed the amorphous nature of all samples, while transmission electron microscopy revealed progressive nanoarchitectural refinement and particle growth with increasing Sm2O3 content, from uniformly dispersed nanodomains to dense agglomerates exhibiting short-range crystalline ordering. Energy-dispersive X-ray spectroscopy and elemental mapping validated the homogeneous incorporation of boron, oxygen, tellurium, and samarium throughout the glass matrix without phase separation. Gamma-ray shielding evaluations showed enhanced mass attenuation coefficients and reduced half-value layers, particularly in the Sm(n)8 sample, with significant performance gains at lower photon energies. Neutron shielding assessments further indicated elevated macroscopic removal cross-section values and dose attenuation, affirming the compositional benefit of Sm2O3 for fast neutron mitigation. It can be concluded that nano-Sm2O3 incorporation would play a multifunctional role on structural and radioprotective properties in addition to morphostructural features of lithium borotellurite glasses
Sensitivity analysis of rotating auxiliary components of a high-speed spindle shaft assembly
No full textMachine tool spindles, complex dynamic systems under thermal growth, are significantly influenced by the shaft assembly’s dimensions, including the spindle shaft and various press-fit auxiliary components. Despite the importance of these dimensions, their effects on the spindle’s dynamic and thermo-mechanical behavior have yet to be sufficiently explored. This study employed a detailed sensitivity analysis for numerous auxiliary components to identify dimensions that most effectively improve the frequency response function (FRF) and minimize thermal growth. The dynamic and thermal analyses were conducted using the receptance coupling substructure analysis (RCSA) and a reduced-order model of finite element model (ROM-FEM), respectively. The findings revealed that, for the considered design, the front stepped sleeve, spindle tail components, and the shaft’s central hole are the most sensitive elements that offer an opportunity to improve spindle performance after bearing optimization
From plant to polymers: micro-processing sisal fiber-reinforced PLA/PHA bio-LFTs at laboratory scale
No full textThis study explores the development of long fiber-reinforced thermoplastic (LFT) composites based on blends of poly(lactic acid) (PLA) and polyhydroxyalkanoate (PHA), reinforced with sisal fibers. A novel lab-scale LFT line was employed to fabricate the long fiber composites, effectively addressing the challenges associated with dispersing and processing high-aspect-ratio natural fibers. The rheological, mechanical, thermal, and morphological properties of the resulting bio-LFT composites were systematically characterized using FTIR, SEM, rotational rheology, mechanical testing, DSC, and TGA. The results demonstrated generally homogeneous fiber dispersion, although limited interfacial adhesion between the fibers and polymer matrix was observed. Mechanical tests revealed that sisal fiber incorporation significantly enhanced tensile strength and stiffness, while impact toughness decreased. Thermal analyses showed improved crystallinity and thermal stability with increasing PHA content and fiber reinforcement. Overall, this work highlights the potential of natural fibers to create high-performance, sustainable biocomposites and lays a solid foundation for future advancements in developing eco-friendly structural materials
Role of shock waves in materials processing: fundamentals and applications
Get PDFIn recent years, ultrasonic processing (USP) technology has led to some of the most promising scientific breakthroughs in the field of pharmaceutical, food, environmental and material sciences leading to advancements in manufacturing, process efficiency, and material performance. However, the industrial scalability of USP still remains a key challenge, largely due to the lack of awareness, standardization and predictive multiphysics models. Optimizing this technology necessitates a bottom-up approach, emphasizing fundamental understanding of the physical phenomena at play prior to scaling-up. Despite the advancements of opto-acoustic characterization tools, the underlying root-cause driving these technological innovations remains unexplored. This paper provides a comprehensive overview of our work carried out in the last 5 years to uncover the fundamental mechanism that governs the deployment of USP in areas related to metal casting, additive manufacturing, production of nanomaterials and composites by employing in-situ high-speed visualizations techniques and characterization of acoustic emissions. The results presented and discussed in this article offer a new perspective on the pivotal role of cavitation-induced shock waves, shifting the focus from being just a by-product, to a primary driver of material modification during USP
Equidistribution for random polynomials and systems of random holomorphic sections
No full textThis article addresses an equidistribution problem concerning the zeros of systems of random holomorphic sections of positive line bundles on compact Kähler manifolds and random polynomials on Cm in the setting of the weighted pluripotential theory. For random polynomials, we consider non-orthonormal bases and prove an equidistribution result which is more general than the ones acquired before for non-discrete probability measures. More precisely, our result demonstrates that the equidistribution holds true even when the random coefficients in the basis representation are not independent and identically distributed (i.i.d.), and moreover, they are not constrained to any particular probability distribution. For random holomorphic sections, by extending the concept of a sequence of asymptotically Bernstein-Markov measures introduced by Bayraktar, Bloom and Levenberg in their recent paper to the setting of holomorphic line bundles over compact Kahler manifolds, we derive a global equidistribution, variance estimate and expected distribution theorems related to the zeros of systems of random holomorphic sections for large tensor powers of a fixed holomorphic line bundle for any codimension k, generalizing a previous result of Bayraktar in his 2016 paper and giving also a positive answer to a question posed in the same paper, asking whether the equidistribution is true for non-projective manifolds. For both random holomorphic polynomials on Cm and systems of random holomorphic sections, the variance estimation method detailed in another paper of the author with Bojnik is significant
Analysis of functions of low differential uniformity in characteristic 2: a new approach (I)
No full textWe introduce a new concept, the APN-defect, which can be thought of as measuring the distance of a given function G : F2n → F2n to the set of almost perfect nonlinear (APN) functions. This concept is motivated by the detailed analysis of the differential behaviour of non-APN functions (of low differential uniformity) G using the so-called difference squares. Indeed, the insight into some structural qualities of S-boxes provided by this new approach is particularly useful in the light of recent refinements of differential cryptanalysis. We describe the relations between the APN-defect and other current concepts of similar nature. Values of APN-defect for several classes of functions of interest, including Dembowski-Ostrom polynomials are given. This enables one to identify the quasi-APN ones, i.e., those with favourable differential behavior. The difference square corresponding to a modification of the inverse function is determined, its APN-defect depending on n is evaluated, the partial quadruple system associated to it is described, and the implications are discussed. In the forthcoming second part of this work we further examine the APN-defect of modifications of the inverse function and address some questions concerning CCZ-equivalence. We also study modifications of classes of functions of low differential uniformity over infinitely many extensions of F2n and present quantitative results on their differential behaviour
Response time analysis of thin film based piezoresistive pressure sensor
No full textThis paper presents a timing analysis of a thin film based gauge piezoresistive pressure sensor, which is designed in COMSOL Multiphysics. In such sensor designs, sensitivity and response time are critical constraints, both of which are influenced by the geometric parameters of the sensor. Sensitivity analysis can be performed using a stationary solver, while response time can be evaluated through time dependent simulations. However, discrepancies may arise between these analyses. These mismatches can be observed by the displacement of the center of the membrane in the time domain. While the sensitivity constraint may meet the design requirements, it must also be achieved within the specified response time. The stationary study provides steady state results; however, reaching a steady state condition within the required response time may not always be feasible. Therefore, to ensure the manufacturability of the sensor, stationary and dynamic analyses must be performed. The findings of this study offer a potential solution to mitigate these mismatches before the manufacturing process
Widom factors in ℂn
No full textWe generalize the theory of Widom factors to the ℂn setting. We define Widom factors of compact subsets K⊂ℂn associated with multivariate orthogonal polynomials and weighted Chebyshev polynomials. We show that on product subsets K=K1×⋯×Kn of ℂn, where each Kj is a non-polar compact subset of ℂ, these quantities have universal lower bounds which directly extend one dimensional results. Under the additional assumption that each Kj is a subset of the real line, we provide improved lower bounds for Widom factors for some weight functions w; in particular, for the case w≡1. Finally, we define the Mahler measure of a multivariate polynomial relative to K⊂ℂn and obtain lower bounds for this quantity on product sets
Exploring the association between urinary incontinence and depression based on a series of large-scale national health studies in Türkiye
Get PDFBackground: Urinary incontinence (UI) and depression are prevalent conditions affecting millions globally and are significantly associated with various demographic, health, and socio-economic factors. This study examines the associations between UI and depression over a 14-year period using nationwide data. Methods: We analyzed cross-sectional data from the Turkish Health Studies Surveys conducted in seven different years between 2008 and 2022, including 125,276 participants aged 15 and older and excluding those with incomplete key health data. Variables included chronic conditions, BMI, depression severity (assessed by PHQ-8), socio-economic status, and lifestyle factors. Univariable and multivariable logistic regression models were used to investigate associations between UI and various risk factors over time. Results: The prevalence of UI and depression fluctuated over the 14 years, with a significant increase observed in 2014. Multivariate analysis confirmed a strong and consistent association between UI and depression across genders and age groups, even after adjusting for confounders. Higher depression severity increased the odds of experiencing UI. Age, multiple comorbidities, higher BMI, and lower socio-economic status were associated with an increased likelihood of UI. Obesity was a significant risk factor for UI in females but not in males. Urban living and higher education levels were inversely associated with UI. The simultaneous rise in UI and depression in 2014 may be linked to socio-economic changes during that period. Conclusions: The findings suggest a robust link between UI and depression, influenced by a complex interplay of health, demographic, and socio-economic factors, needing prospective studies to further investigate the causal pathway of these associations
Generating satisfiable benchmark instances for stable roommates problems with optimization
Get PDFWhile the existence of a stable matching for the stable roommates problem possibly with incomplete preference lists (SRI) can be decided in polynomial time, SRI problems with some fairness criteria are intractable. Egalitarian SRI that tries to maximize the total satisfaction of agents if a stable matching exists, is such a hard variant of SRI. For experimental evaluations of methods to solve these hard variants of SRI, several well-known algorithms have been used to randomly generate benchmark instances. However, these benchmark instances are not always satisfiable and usually have a small number of stable matchings if one exists. For such SRI instances, despite the NP-hardness of Egalitarian SRI, it is practical to find an egalitarian stable matching by enumerating all stable matchings. In this study, we introduce a novel algorithm to generate benchmark instances for SRI that have very large numbers of solutions, and for which it is hard to find an egalitarian stable matching by enumerating all stable matchings