Hakkari Üniversitesi Akademik Veri Yönetim Sistemi
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THE EFFECT OF ANNEALING POLY(LACTIC ACID) PRODUCED BY ADDITIVEMANUFACTURING AT DIFFERENT TEMPERATURES ON ITS MECHANICALPROPERTIES
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Flux Pinning and Levitation Stability in SiC-Doped MgB₂ Superconductors Prepared by Spark Plasma Sintering
No full textIn this study, MgB₂ bulk superconductors doped with 0–20% wt SiC were synthesized via in‑situ Spark Plasma Sintering (SPS), and their physical and magnetic properties were systematically investigated. Resistivity–temperature (ρ–T) and H–T phase diagram analyses revealed that while increasing SiC content reduces the transition temperature (Tc) and broadens the transition width (ΔTc), it simultaneously enhances flux pinning and magnetic stability through a dual mechanism. Specifically, partial decomposition of SiC at 850 °C leads to carbon substitution in the MgB₂ lattice, increasing electron scattering and creating effective lattice distortions, while residual SiC nanoparticles and Mg₂Si secondary phases act as volumetric and intergranular pinning centers. Critical current density (Jc) and normalized pinning force (Fp/Fp,max) analyses confirmed strong pinning performance, particularly at 10–15% wt doping levels, where both Jc and Hirr were maximized. Vertical and lateral levitation force measurements under zero‑field‑cooled (ZFC) and field‑cooled (FC) conditions further demonstrated that the 15% wt sample exhibited the most stable flux trapping capacity, maintaining strong magnetic response even near the superconducting transition. Notably, the sample with 5% wt SiC addition exhibited the highest critical current density of 1.08 × 106 A/cm2 at 20 K under self-field, confirming the effectiveness of optimized doping for high-performance applications.These results confirm that controlled SiC doping and SPS processing effectively tailor MgB₂ bulk superconductors for high‑performance magnetic and levitation applications
Coupled fermion-antifermion pairs within a traversable wormhole
No full textThis study investigates the dynamics of fermion-antifermion (f-f) pairs within a traversable wormhole (TWH) spacetime by solving the two-body covariant Dirac equation with a position-dependent mass m→m(r)In the context of a static, radially symmetric (2+1)-dimensional TWH characterized by a constant redshift function and a given shape function, we explore two Lorentz scalar potentials: (i) a Coulomb-like potential and (ii) an exponentially decaying potential. The Coulomb potential leads to positronium-like binding energies, with the ground state (n=0) Ebn≈−mec2α2/4≈−6.803 eV. On the other hand, the exponential potential establishes critical mass thresholds, mc=(n+1/2)ℏ/(2cλc), at which the energy approaches zero, causing the system to cease to exist over time. Stability is maintained when n+1/2<2 resulting in oscillatory behavior, while n+1/2 >2 leads to decay. The energy spectrum reveals essential features of the system, and the wavefunction reflects the influence of the wormhole’s throat, shaping spatial configurations and probability distributions. This work enhances our understanding of quantum phenomena in curved spacetimes and establishes connections to condensed matter physics.This study investigates the dynamics of fermion-antifermion (f-f) pairs within a traversable wormhole (TWH) spacetime by solving the two-body covariant Dirac equation with a position-dependent mass m→m(r)In the context of a static, radially symmetric (2+1)-dimensional TWH characterized by a constant redshift function and a given shape function, we explore two Lorentz scalar potentials: (i) a Coulomb-like potential and (ii) an exponentially decaying potential. The Coulomb potential leads to positronium-like binding energies, with the ground state (n=0) Ebn≈−mec2α2/4≈−6.803 eV. On the other hand, the exponential potential establishes critical mass thresholds, mc=(n+1/2)ℏ/(2cλc), at which the energy approaches zero, causing the system to cease to exist over time. Stability is maintained when n+1/2<2 resulting in oscillatory behavior, while n+1/2 >2 leads to decay. The energy spectrum reveals essential features of the system, and the wavefunction reflects the influence of the wormhole’s throat, shaping spatial configurations and probability distributions. This work enhances our understanding of quantum phenomena in curved spacetimes and establishes connections to condensed matter physics.</p
ÖĞRETMEN GÖRÜŞLERİ BAĞLAMINDA YENİLİKÇİ ÖĞRETİM YÖNTEMLERİNE YÖNELİK TUTUMLAR, UYGULAMALAR VE KARŞILAŞILAN ZORLUKLAR: NİTEL BİR ARAŞTIRMA
No full textEvaluation of the Interview System Applied in 2024 Teacher Appointments from the Perspective of Branch Teachers Participating in this Process
No full textDielectric properties and polarization mechanisms of the DLC-interlayered Schottky structures under low-moderate and high-temperatures
No full textThe primary objective of this study is to elucidate the temperature-dependent polarization mechanisms of the diamond-like carbon (DLC) interlayered Schottky structures (SSs). The capacitance/conductance data were obtained for the temperature range of 80–410 K to achieve this objective, and the impedance spectroscopy method was utilized to ascertain the fundamental dielectric parameters, encompassing dielectric constant, dielectric loss, loss tangent, ac-conductivity, and electric modulus. Consequently, a significant behavioral disparity was observed by the parameters across three distinct temperature ranges, and these regions were classified as low (LTs), moderate (MTs), and high temperatures (HTs). The experimental findings have also demonstrated that various polarization mechanisms were either collectively or individually effective for the specific temperature regions. To elaborate further, it was understood that dipole polarization and trapping mechanisms were predominant in LTs, while Maxwell-Wagner mechanisms predominate in MTs. It has also been determined that space charge and Maxwell-Wagner polarizations were dominant mechanisms in HTs
The effect of social anxiety on student interactions in asynchronous online discussion forums as mediated by social presence and moderated by anonymity
No full textPervasive internet use in higher education has rendered social anxiety a lesser problem in circumventing interactions. However, the attenuation of vitality in interactions still remains a contentious issue, especially in asynchronous online discussions. This study aims to elucidate how anonymity and social presence affect the relationship between avoidance of interaction and peer and content interaction in online discussions. In the true experimental study, we recruited 123 first-year university students, of which 62 were randomly assigned to the anonymous group, and 61 to the identified group. This paper adopts a moderated mediation model, in which anonymity and social presence are included as moderator and mediator, respectively. We revealed that the “straightforward” relationship between avoidance of interaction and peer and content interaction is actually highly complex. The results substantiate a full mediation of social presence and moderation of anonymity in favor of disclosed identity. This study accentuates the critical role of social presence in fostering interactions. The results also suggest that disclosing discussants’ identities might be useful during asynchronous interactions in online discussions for increasing social presence only if their avoidance of interaction is low; in the case of a high avoidance of interaction, anonymity should be preferred
