检索结果-内蒙古大学图书馆

Thermal properties of structurally balanced systems on diluted and densified triangulations

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Woloszyn, Maciej Malarz, Krzysztof AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland

The dynamics of social relations and the possibility of reaching the state of structural balance (Heider balance) are discussed for various networks of interacting actors under the influence of the temperature modeling the social noise level. For that purpose, two main types of lattices are considered. The first is created by removing some links from a regular triangular lattice to produce a diluted triangular lattice, and the second by adding more links to create an enhanced triangular lattice. In both those cases, the full range of possible graph densities is discussed, limited by the extreme cases of networks which consist of a small number of separated triads and fully connected networks. It is shown that the existence of the balanced state is not possible if the average node degree is too close to the value characterizing the regular triangular lattice. Otherwise, both balanced (or partially balanced) and imbalanced states are possible, depending on the temperature. However, only for graphs which are dense enough a phase transition of the first kind is observed, while less enhanced networks (and all diluted) indicate a smooth cross-over between the two states. The crossover temperatures are size-independent only for the diluted triangular lattices and depend on the size of the system for the enhanced triangular lattices, as is the case also for the critical temperatures of the phase transition observed in denser enhanced lattices. © 2021, CC BY.

关键词： Hadrons

Coexisting magnetic structures and spin reorientation in Er0.5Dy0.5FeO3: Bulk magnetization, neutron scattering, specific heat, and density functional theory studies

学校读者我要写书评

暂无评论

Physical Review B 2022年第21期105卷 214436-214436页

作者： Sarita Rajput Padmanabhan Balasubramanian Ankita Singh Françoise Damay C. M. N. Kumar W. Tabis T. Maitra V. K. Malik Department of Physics Indian Institute of Technology Roorkee Roorkee 247 667 India Department of Physics Graphic Era University Dehradun Uttarakhand 248 002 India Laboratoire Léon Brillouin CEA-CNRS CEA/Saclay 91191 Gif-sur-Yvette France Institute of Solid State Physics Vienna University of Technology Wiedner Hauptstrasse 8-10 1040 Vienna Austria AGH University of Science and Technology Faculty of Physics and Applied Computer Science 30-059 Kraków Poland

The complex magnetic structures, spin reorientation, and associated exchange interactions have been investigated in Er0.5Dy0.5FeO3 using bulk magnetization, neutron diffraction, specific heat measurements, and density functional theory calculations. The Fe3+ spins order as G-type antiferromagnet structure depicted by Γ4(Gx, Ay, Fz) irreducible representation below 700 K, similar to its end compounds. The bulk magnetization data indicate occurrence of the spin-reorientation and rare-earth magnetic moments' polarization below ∼75 K and 10 K, respectively. The neutron diffraction studies confirm an “incomplete” Γ4→ Γ2(Fx, Cy, Gz) spin-reorientation initiated ≤75 K. Although the relative volume fraction of the two magnetic structures varies with decreasing temperature, both coexist even at 1.5 K. Below 10 K, the polarization of Er3+/Dy3+ moments in a cyR arrangement develops, which gradually increases with decreasing temperature. At 2 K, magnetic structure associated with czR arrangement of Er3+/Dy3+ moments also appears. At 1.5 K, while the rare-earth magnetic moments show a cyR+czR-type arrangement, the Fe3+ spins are represented by a combination of a Γ2+Γ4 (Gz,Gx) arrangement. A clear signature of the magnetic structure with Γ1(Gy) representation, symmetrically compatible with the czR-type arrangement of rare-earth moments, is not confirmed from the refinement of the neutron diffraction data. The observed Schottky anomaly at 2.5 K suggests that the “rare-earth ordering” is induced by polarization due to Fe3+ spins. The Er3+−Fe3+ and Er3+−Dy3+ exchange interactions, obtained from first principle calculations, indicate that these interactions primarily cause the complicated spin reorientation and cyR rare-earth ordering in the system, respectively, while the dipolar interactions between rare-earth moments result in the czR type rare-earth ordering at 2 K.

关键词： Antiferromagnetism Exchange interaction Magnetic interactions Magnetic order Magnetism Density functional calculations Magnetization measurements Neutron diffraction Specific heat measurements X-ray diffraction

Reaction-diffusion transport into core-shell geometry: Well-posedness and stability of stationary solutions

学校读者我要写书评

暂无评论

arXiv 2023年

作者： de Jong, Thomas Geert Prokert, Georg Sterk, Alef Faculty of Mathematics and Physics Institute of Science and Engineering Kanazawa University Kanazawa Japan Faculty of Mathematics and Computer Science Center for Analysis Scientific Computing and Applications Eindhoven University of Technology Eindhoven Netherlands Bernoulli Institute for Mathematics Computer Science and Artificial Intelligence University of Groningen Groningen Netherlands

We investigate a nonlinear parabolic reaction-diffusion equation describing the oxygen concentration in encapsulated pancreatic cells with a general core-shell geometry. This geometry introduces a discontinuous diffusion coefficient as the material properties of the core and shell differ. We apply monotone operator theory to show well-posedness of the problem in the strong form. Furthermore, the stationary solutions are unique and asymptotically stable. These results rely on the gradient structure of the underlying *** Codes 92C50, 35K55, 34K20 Copyright © 2023, The Authors. All rights reserved.

关键词： Asymptotic stability

Transverse Field Dependence of the Ground State in the Z2 Bose-Hubbard Model

学校读者我要写书评

暂无评论

arXiv 2025年

作者： Watanabe, Yuma Watabe, Shohei Nikuni, Tetsuro Department of Physics Tokyo University of Science Shinjuku Tokyo162-8601 Japan Faculty of Engineering Computer Science and Engineering Shibaura Institute of Technology 3-7-5 Toyosu Koto-ku Tokyo135-8548 Japan

The study of interaction between the particle and lattice degrees of freedom is one of the central interests in the quantum many-body systems. The Z2 Bose-Hubbard model has been proposed to describe ultracold bosons in a dynamical optical lattice. This model introduces the lattice degrees of freedom by placing half-spins on the bonds between neighboring lattice sites. In this study, we investigate the effect of spin fluctuations on the ground state by using the density-matrix renormalization group method. By calculating the spin structure factor and the compressibility, we show that there is a phase transition between two spatially nonuniform states. We also discuss the ground state in the strong transverse magnetic limit. © 2025, CC BY.

关键词： Hubbard model

Recent results on central exclusive production with the STAR detector

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Sikora, Rafal Faculty of Physics and Applied Computer Science AGH University of Science and Technology 30 Mickiewicza Ave. Kraków30-059 Poland

We present results on the Central Exclusive Production of charged particle pairs h+h− (h = π, K, p), pp → p + h+h− + p, obtained with the STAR experiment at RHIC in proton-proton collisions at a center-of-mass energy of ps = 200 GeV. All final-state particles were reconstructed, including forward-scattered protons detected in the Roman Pot system. As a result, the Double Pomeron Exchange (DPE) events were selected and the non-exclusive backgrounds were efficiently rejected. Differential fiducial cross sections were measured as functions of observables related to the central hadronic final state and to the forward-scattered protons. The measured cross sections were compared to phenomenological model predictions based on the DPE. We also present preliminary results on the measurement of the same physics process at higher collision energy √s = 510 GeV. The data demonstrate features similar to those observed at √s = 200 GeV. Copyright © 2021, The Authors. All rights reserved.

关键词： Stars

Percolation thresholds on triangular lattice for neighbourhoods containing sites up-to the fifth coordination zone

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Malarz, Krzysztof Agh University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland

We determine thresholds pc for random-site percolation on a triangular lattice for all available neighborhoods containing sites from the first to the fifth coordination zones, including their complex combinations. There are 31 distinct neighbourhoods. The dependence of the value of the percolation thresholds pc on the coordination number z are tested against various theoretical predictions. The newly proposed single scalar index ξ = Σizir2i=i (depending on the coordination zone number i, the neighbourhood coordination number z and the square-distance r2to sites in i-th coordination zone from the central site) allows to differentiate among various neighbourhoods and relate pcto ξ. The thresholds roughly follow a power law pc∝ ξ-γwith γ ≈ 0.710(19). © 2021, CC BY.

关键词： Percolation (fluids)

Towards the Heider balance - A cellular automaton with a global neighborhood

学校读者我要写书评

暂无评论

arXiv 2021年

作者： Krawczyk, Malgorzata J. Kulakowski, Krzysztof Burda, Zdzislaw AGH University of Science and Technology Faculty of Physics and Applied Computer Science al. Mickiewicza 30 Kraków30-059 Poland

We study a simple deterministic map that leads a fully connected network to Heider balance. The map is realized by an algorithm that updates all links synchronously in a way depending on the state of the entire network. We observe that the probability of reaching a balanced state increases with the system size N. Jammed states become less frequent for larger N. The algorithm generates also limit cycles, mostly of length 2, but also of length 3, 4, 6, 12 or 14. We give a simple argument to estimate the mean size of basins of attraction of balanced states and discuss symmetries of the system including the automorphism group as well as gauge invariance of triad configurations. We argue that both the symmetries play an essential role in the occurrence of cycles observed in the synchronous dynamics realized by the algorithm. Copyright © 2021, The Authors. All rights reserved.

关键词：

Non-Gaussian behavior in fractional Laplace motion with drift

学校读者我要写书评

暂无评论

Physical Review E 2025年第3期111卷 034121-034121页

作者： Wei Wang Yingjie Liang Aleksei V. Chechkin Ralf Metzler Institute of Physics and Astronomy University of Potsdam 14476 Potsdam Germany College of Mechanics and Engineering Science Hohai University 211100 Nanjing China Faculty of Pure and Applied Mathematics Hugo Steinhaus Center Wrocław University of Science and Technology 50-370 Wrocław Poland German-Ukrainian Core of Excellence Max Planck Institute of Microstructure Physics Weinberg 2 06120 Halle Germany Asia Pacific Centre for Theoretical Physics Pohang 37673 Republic of Korea

We study fractional Laplace motion (FLM) obtained from subordination of fractional Brownian motion (FBM) to a gamma process in the presence of an external drift that acts on the composite process or of an internal drift acting solely on the parental process. We derive the statistical properties of this FLM process and find that the external drift does not influence the mean-squared displacement, whereas the internal drift leads to normal diffusion, dominating at long times in the subdiffusive Hurst exponent regime. We also investigate the intricate properties of the probability density function (PDF), demonstrating that it possesses a central Gaussian region whose expansion in time is influenced by FBM's Hurst exponent. Outside of this region, the PDF follows a non-Gaussian pattern. The kurtosis of this FLM process converges toward the Gaussian limit at long times insensitive to the extreme non-Gaussian tails. Additionally, in the presence of the external drift, the PDF remains symmetric and centered at x=vt. In contrast, for the internal drift this symmetry is broken. The results of our computer simulations are fully consistent with the theoretical predictions. The FLM model is suitable for describing stochastic processes with a non-Gaussian PDF and long-ranged correlations of the motion.

关键词： Probability density function

Spectroscopic properties of lead-silicate glasses with MoO3 admixture and rare earth dopants

学校读者我要写书评

暂无评论

Spectroscopic properties of lead-silicate glasses with MoO3 ...

International Conference on Transparent Optical Networks

作者： K. Wisniewski M. Środa K. Naveenkumar P. Syam Prasad P. Płóciennik A. Zawadzka Institute of Physics Faculty of Physics Astronomy and Informatics Nicolaus Copernicus University Grudziadzka 5 Torun Poland Centre for Modern Interdisciplinary Technologies Nicolaus Copernicus University in Torun Wilenska 4 Torun Poland Faculty of Material Science and Ceramics AGH University of Science and Technology A. Mickiewicza 30 Krakow Poland Department of Physics National Institute of Technology Warangal Warangal Telangana State India Institute of Engineering and Technology Faculty of Physics Astronomy and Informatics Nicolaus Copernicus University in Torun ul. Grudziadzka 5 Torun Poland

ISBN: (数字)9798350377323

ISBN: (纸本)9798350377330

The spectroscopic properties of lead-silicate glass containing $2 \mathrm{~mol}_{2} \mathrm{MoO}_{3}$ and rare earth dopants were investigated in detail. Three glass series were prepared, varying the concentrations of $\mathrm{Pr}, \mathrm{Nd}$, and Er from 0.5 to $1.5 \mathrm{~mol} \%$ each. The addition of MoO 3 was found to have a significant impact on the optical properties of the glass, manifesting in an elevation of the refractive index and a reduction in dispersion [1, 2]. The influence of molybdenum ions and rare earth dopants was examined through absorption, excitation, and luminescence spectra analyses [3]. Luminescence decay times were measured under both ambient conditions and within a temperature range spanning from 10 K to 350 K. Preliminary luminescence data for the glasses at room temperature are illustrated in Fig. 1.

关键词： Temperature measurement Temperature distribution Particle beam optics Refractive index Glass Luminescence Lead