Journal articles: 'Pinning model'

1

Karmakar, S., and G. Parisi. "Random pinning glass model." Proceedings of the National Academy of Sciences 110, no. 8 (2013): 2752–57. http://dx.doi.org/10.1073/pnas.1222848110.

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Caravenna, Francesco, Rongfeng Sun, and Nikos Zygouras. "The continuum disordered pinning model." Probability Theory and Related Fields 164, no. 1-2 (2014): 17–59. http://dx.doi.org/10.1007/s00440-014-0606-4.

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3

Pan, A. V., S. V. Pysarenko, and S. Dou. "A pinning model and universal pinning regimes in YBa2Cu3O7 superconducting films." Physica C: Superconductivity and its Applications 470 (December 2010): S857—S859. http://dx.doi.org/10.1016/j.physc.2009.11.077.

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4

Torri, Niccolò. "Pinning model with heavy tailed disorder." Stochastic Processes and their Applications 126, no. 2 (2016): 542–71. http://dx.doi.org/10.1016/j.spa.2015.09.010.

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5

Kao, Hsien-Chung, Shih-Chang Lee, and Wen-Jer Tzeng. "Frenkel-Kontorova model with pinning cusps." Physica D: Nonlinear Phenomena 107, no. 1 (1997): 30–42. http://dx.doi.org/10.1016/s0167-2789(97)00055-9.

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6

Akasaka, Yasushi, Genji Nakamura, Kenji Shiraishi, et al. "Modified Oxygen Vacancy Induced Fermi Level Pinning Model Extendable to P-Metal Pinning." Japanese Journal of Applied Physics 45, No. 49 (2006): L1289—L1292. http://dx.doi.org/10.1143/jjap.45.l1289.

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7

Zablotskii, V., and T. Polyakova. "Flux pinning model and pinning pressure in superconductors with randomly distributed columnar defects." physica status solidi (b) 236, no. 2 (2003): 404–7. http://dx.doi.org/10.1002/pssb.200301690.

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8

ZHU, B. Y. "ANOMALOUS HALL EFFECT IN WEAK PINNING HIGH-Tc SUPERCONDUCTORS." Modern Physics Letters B 10, no. 25 (1996): 1227–36. http://dx.doi.org/10.1142/s0217984996001395.

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Taking into account both pinning and thermal fluctuation and employing the single flux flow model of Wang, Dong, and Ting (WDT), we have performed numerical study to investigate the flux motion in the weak pinning environment in the mixed-state of high-Tc superconductors. We find that there exist two kinds of weak pinning regime, one possesses low pinning concentration but strong individual pinning potentials, the other consists of high pinning concentration but weak individual pinning potentials for the double sign reversal of Hall resistivity ρxy. Moreover, our simulation and analysis suggest that the weak collective pinning effect may not be a good reason for the abnormal Hall effect. These results are well consistent with recent measurement of Bi2Sr2CaCu2O8 (BSCCO), Tl2Ba2CaCu2O8 (TBCCO) and HgBa2CaCu2O6 (HBCCO) and collective pinning theories for Hall effect.

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9

Dos Santos, Mickaël, and Oleksandr Misiats. "Ginzburg-Landau model with small pinning domains." Networks & Heterogeneous Media 6, no. 4 (2011): 715–53. http://dx.doi.org/10.3934/nhm.2011.6.715.

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10

Iron, David, and Michael J. Ward. "Spike pinning for the Gierer–Meinhardt model." Mathematics and Computers in Simulation 55, no. 4-6 (2001): 419–31. http://dx.doi.org/10.1016/s0378-4754(00)00303-7.

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11

NAYAK, SUHAS. "AN EQUILIBRIUM-BASED MODEL OF STOCK-PINNING." International Journal of Theoretical and Applied Finance 10, no. 03 (2007): 535–55. http://dx.doi.org/10.1142/s0219024907004287.

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We consider a model of the economy that splits investors into two groups. One group (the reference traders) trades an underlying asset according to the difference in realized returns between that asset and some evolving consensus estimate of those returns; the other group (hedgers) hedge options, namely straddles, on the underlying asset. We consider the cases when hedgers are long the straddle and when the hedgers are short the straddle. We numerically simulate the terminal distribution of the underlying asset price and find that hedgers that are long the straddle tend to push the underlying toward the strike, while hedgers that are short the straddle cause the underlying security to have a bimodal terminal probability distribution with a local minimum at the strike.

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12

Check, Erika. "Treasure island: pinning down a model ecosystem." Nature 439, no. 7075 (2006): 378–79. http://dx.doi.org/10.1038/439378a.

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13

Berger, Quentin, and Fabio Lucio Toninelli. "Hierarchical pinning model in correlated random environment." Annales de l'Institut Henri Poincaré, Probabilités et Statistiques 49, no. 3 (2013): 781–816. http://dx.doi.org/10.1214/12-aihp493.

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14

Li, Kai, Yao Shen, Da Yong Li, and Ying Hong Peng. "Phase Field Study of Second Phase Particles-Pinning on Strain Induced Grain Boundary Migration." Materials Science Forum 993 (May 2020): 967–75. http://dx.doi.org/10.4028/www.scientific.net/msf.993.967.

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A phase field model was presented to investigate the effect of particles-pinning on grain boundary migration in materials containing stored energy differences across the grain boundaries. The accuracy of the phase field framework was examined by comparing the simulated results with theoretical predictions. The pinning effects of coherent and non-coherent second phase particles on the boundary migration were studied in triple-grain models. 2D simulations with second phase particles of different sizes or different area fractions were performed. The effect of stored energy difference across the boundary on the particles-pinning was also investigated. The results showed that the pinning effect could be enhanced by the decrement of the particle size and the increment of particle area fraction. Increasing the stored energy difference across the grain boundary induced higher grain boundary migration velocity and weaker particles-pinning.

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15

Farmer, J. W., M. Kornecki, and D. L. Cowan. "Flux Pinning and Defects in As-Grown and Neutron Irradiated Y-123 Crystals." International Journal of Modern Physics B 12, no. 29n31 (1998): 3267–70. http://dx.doi.org/10.1142/s0217979298002441.

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A model of cooperative pinning where the pinning potential U(j) is inversely proportional to j accurately describes flux creep in high quality single crystals of Y-123 in the single fluxoid creep regime. In contrast, for strong pinning the pinning potential varies as (1-j/j max )3/2. Plots of the function S(j)=d ln (U)/d ln (j) provide a sensitive test for distinguishing between these two pinning mechanisms. Several crystals grown and annealed under different conditions have been analyzed. We find that we can prepare single crystals in either pinning class, depending on the growth and annealing process. It is suggested that strong pinning occurs when the growth and annealing processing lead to the formation of precipitates with nearly optimum size distribution. Strong pinning effects are also observed in fast neutron irradiated samples.

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16

Yoo, M. H., and C. T. Liu. "Effect of prestress on tensile yield strength of a Ni3Al alloy." Journal of Materials Research 3, no. 5 (1988): 845–47. http://dx.doi.org/10.1557/jmr.1988.0845.

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An experimental technique of prestressing and quenching was employed in order to elucidate the nature of pinning points responsible for the anomalous yield strength of Ni3Al. The apparent number density of pinning points at room temperature was found to be unaffected by the prestressing and quenching from elevated temperatures. This result is consistent with the crossslip-pinning (CSP) model in that cross-slipped segments act as pinning points on the leading superpartial dislocations.

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17

Shahandeh, Sina, and Matthias Militzer. "Modelling of Particle Pinning in Dual Scale Using Phase Field Method." Materials Science Forum 715-716 (April 2012): 764–69. http://dx.doi.org/10.4028/www.scientific.net/msf.715-716.764.

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Modelling the evolution of structures in polycrystalline materials with distributions of fine particles requires integration of multiple length scales. Grain boundaries interact with particles on the scale of the particle diameters. The particle pinning force controls the kinetics of grain growth. Grain diameters can be several orders of magnitude larger than particles. In this work, a methodology is proposed to combine two sets of phase field models at different length scales. At the smaller scale, the effect of particles on movement of a single grain boundary is modelled in a small domain with a high grid resolution. The interface moves in an array of particles with specified shape and size distributions. The average pinning force exerted by the particles, is calculated from the interface velocity. Then, an effective driving force model is developed to incorporate the obtained pinning force into the large scale where grain growth simulations are preformed. In this model, the particle pinning force is subtracted from the driving force in the phase field formulation. In this effective formulation, particles are not resolved in the calculation grid. Therefore, with the larger numerical mesh, modelling of larger systems is possible. Kinetics of grain growth was studied with 2 dimensional simulations. Keywords: Phase field modelling, particle pinning, grain growth

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18

Harun, Azmir, Mark A. Miodownik, Mike P. Clode, and Elizabeth A. Holm. "Modelling Zener Pinning: A Comparison of Different Computer Simulation Methods." Materials Science Forum 467-470 (October 2004): 1033–38. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.1033.

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We compare the ability of three different types of microstructural model to simulate particle pinning. The microstructural models are the Phase Field model, the Front Tracking model and the Monte Carlo Potts model. The same 3D test geometry is simulated using each method. This is an hexagonal network with spherical particles located at the centre of each hexagonal grain. The hexagonal grain network provides a constant driving force for a moving boundary and includes triple line and quadruple point motion. This geometry allows detailed investigation of the boundary/particle interaction. The pinning force acting on the migrating curved grain boundary is calculated and compared with theoretical predictions for each model.

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19

Zhou, Wen Quan, Ying Juna Gao, Yao Liu, Zhi Rong Luo, and Chuang Gao Huang. "Phase Field Model for Grain Growth with Second-Phase Particles of Stick Shape." Advanced Materials Research 741 (August 2013): 3–6. http://dx.doi.org/10.4028/www.scientific.net/amr.741.3.

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The phase field method was applied to study the effect of second-phase particles (SPP) with different geometric orientations and shapes on grain growth. The results show that, in the grain growth process, most of the spherical second-phase particles located at triple junctions, while the stick SPPs located at the grain boundaries along the grain boundary. The second-phase particles are of the strong pinning effect on grain boundary and the limiting grain radius can be expressed by Zener relations. In the condition of the second-phase particles area fraction and size remaining the same, the stick SPPs are of more effective pinning on grain growth than that for spherical SPPs, and the orientation of disk second-phase particles is also an influence factor for pinning effect. Stick second-phase particles with multiple orientations can make a better pining effect than those with only one orientation.

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20

Koblischka, Michael R., Anjela Koblischka-Veneva, Jörg Schmauch, and Masato Murakami. "Microstructure and Flux Pinning of Reacted-and-Pressed, Polycrystalline Ba0.6K0.4Fe2As2 Powders." Materials 12, no. 13 (2019): 2173. http://dx.doi.org/10.3390/ma12132173.

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The flux pinning properties of reacted-and-pressed Ba0.6K0.4Fe2As2 powder were measured using magnetic hysteresis loops in the temperature range 20 K ≤ T ≤ 35 K. The scaling analysis of the flux pinning forces ( F p = j c × B , with j c denoting the critical current density) following the Dew-Hughes model reveals a dominant flux pinning provided by normal-conducting point defects ( δ l -pinning) with only small irreversibility fields, H irr , ranging between 0.5 T (35 K) and 16 T (20 K). Kramer plots demonstrate a linear behavior above an applied field of 0.6 T. The samples were further characterized by electron backscatter diffraction (EBSD) analysis to elucidate the origin of the flux pinning. We compare our data with results of Weiss et al. (bulks) and Yao et al. (tapes), revealing that the dominant flux pinning in the samples for applications is provided mainly by grain boundary pinning, created by the densification procedures and the mechanical deformation applied.

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21

Berger, Quentin. "Influence of Disorder For the Polymer Pinning Model." ESAIM: Proceedings and Surveys 51 (October 2015): 74–88. http://dx.doi.org/10.1051/proc/201551005.

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22

Wlodarski, Z. "The Jiles-Atherton model with variable pinning parameter." IEEE Transactions on Magnetics 39, no. 4 (2003): 1990–92. http://dx.doi.org/10.1109/tmag.2003.812716.

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23

HARUN, A., E. HOLM, M. CLODE, and M. MIODOWNIK. "On computer simulation methods to model Zener pinning." Acta Materialia 54, no. 12 (2006): 3261–73. http://dx.doi.org/10.1016/j.actamat.2006.03.012.

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24

BERGER, SOPHIE, LIONEL FAVIER, REINHARD DREWS, JEAN-JACQUES DERWAEL, and FRANK PATTYN. "The control of an uncharted pinning point on the flow of an Antarctic ice shelf." Journal of Glaciology 62, no. 231 (2016): 37–45. http://dx.doi.org/10.1017/jog.2016.7.

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ABSTRACTAntarctic ice shelves are buttressed by numerous pinning points attaching to the otherwise freely-floating ice from below. Some of these kilometric-scale grounded features are unresolved in Antarctic-wide datasets of ice thickness and bathymetry, hampering ice flow models to fully capture dynamics at the grounding line and upstream. We investigate the role of an 8.7 km2 pinning point at the front of the Roi Baudouin Ice Shelf, East Antarctica. Using ERS interferometry and ALOS-PALSAR speckle tracking, we derive, on a 125 m grid spacing, surface velocities deviating by −5.2 ± 4.5 m a−1 from 37 on-site global navigation satellite systems-derived velocities. We find no evidence for ice flow changes on decadal time scales and we show that ice on the pinning point virtually stagnates, deviating the ice stream and causing enhanced horizontal shearing upstream. Using the BISICLES ice-flow model, we invert for basal friction and ice rigidity with three input scenarios of ice velocity and geometry. We show that inversion results are the most sensitive to the presence/absence of the pinning point in the bathymetry; surface velocities at the pinning point are of secondary importance. Undersampling of pinning points results in erroneous ice-shelf properties in models initialised by control methods. This may impact prognostic modelling for ice-sheet evolution in the case of unpinning.

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25

CAO, Z. S., Y. ZHANG, and Z. X. ZHAO. "INTRINSIC FLUX PINNING FORCE IN HIGH Tc OXIDE SUPERCONDUCTORS." Modern Physics Letters B 04, no. 19 (1990): 1227–36. http://dx.doi.org/10.1142/s0217984990001549.

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A phenomenological model concerning the intrinsic flux pinning in high transition temperature oxide superconductors was proposed. The coherence length of this type of superconductors is sufficiently short to enable the layer structure along the c-axis in crystal specimens to provide by itself the flux pinning centers which have the considerably large flux pinning force. The critical current density estimated from this mechanism is also large.

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26

GRADINARU, MIHAI, and SAMY TINDEL. "ON HOMOGENEOUS PINNING MODELS AND PENALIZATIONS." Stochastics and Dynamics 08, no. 03 (2008): 383–96. http://dx.doi.org/10.1142/s0219493708002366.

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In this note, we show how the penalization method, introduced in order to describe some nontrivial changes of the Wiener measure, can be applied to the study of some simple polymer models such as the pinning model. The bulk of the analysis is then focused on the study of a martingale which has to be computed as a Markovian limit.

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27

Cai, Zhi-Xiong, David O. Welch, and Girija S. Dubey. "Isothermal Elastic Constants of Flux-Line Lattice in Layered Superconductors." International Journal of Modern Physics B 12, no. 29n31 (1998): 2974–81. http://dx.doi.org/10.1142/s0217979298001897.

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A model of the effective interaction between the magnetic flux-lines in a layered superconductor is derived from the Lawrence–Doniach model. We show analytically that the intralayer interaction energy can be evaluated using the Ewald summation technique. The melting of flux line lattices is studied using Langevin dynamics simulation of the model with various values of interlayer coupling strength and pinning intensities. The thermal fluctuation terms of the isothermal shear modulus are found to increase sharply at the melting transition temperature for systems with or without pinning, while the structural order parameters were close to zero at all temperatures for systems with strong pinning. The melting of the pinned flux-line lattice is discussed in the context of its elastic properties.

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Celora, T., V. Khomenko, M. Antonelli, and B. Haskell. "The effect of non-linear mutual friction on pulsar glitch sizes and rise times." Monthly Notices of the Royal Astronomical Society 496, no. 4 (2020): 5564–74. http://dx.doi.org/10.1093/mnras/staa1930.

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ABSTRACT Observations of pulsar glitches have the potential to provide constraints on the dynamics of the high density interior of neutron stars. However, to do so, realistic glitch models must be constructed and compared to the data. We take a step towards this goal by testing non-linear models for the mutual friction force, which is responsible for the exchange of angular momentum between the neutron superfluid and the observable normal component in a glitch. In particular, we consider a non-linear dependence of the drag force on the relative velocity between superfluid vortices and the normal component, in which the contributions of both kelvin and phonon excitations are included. This non-linear model produces qualitatively new features, and is able to reproduce the observed bimodal distribution of glitch sizes in the pulsar population. The model also suggests that the differences in size distributions in individual pulsars may be due to the glitches being triggered in regions with different pinning strengths, as stronger pinning leads to higher vortex velocities and a qualitatively different mutual friction coupling with respect to the weak pinning case. Glitches in pulsars that appear to glitch quasi-periodically with similar sizes may thus be due to the same mechanisms as smaller events in pulsars that have no preferred glitch size, but simply originate in stronger pinning regions, possibly in the core of the star.

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29

Hasan, MN, and M. Muralidhar. "Investigation of Pinning Force Density F_p and Critical Current Density J_c of Nd_0.33Eu_0.33Gd_0.33Ba₂Cu₃O_y(NEG-123) Superconductors with Addition of 211 Phase Particles and Analysis with a Theoretical Evaluation Based on Flux Creep-Flow Model." Chittagong University Journal of Science 42, no. 1 (2021): 24–38. http://dx.doi.org/10.3329/cujs.v42i1.54236.

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The pinning force density Fp and the critical current density Jc were investigated in Nd0.33Eu0.33Gd0.33Ba2Cu3O(NEG-123) superconductors with addition of NEG-211 and EG-211 secondary phase particles of the volume fractions up to 10 mol% by analyzing experimental data of DC magnetization and compared with theoretical calculation based on flux creep-flow model taking the pinning parameter into account. The pinning parameters such that the number of flux lines in the flux bundle (g2), the most probable value of pinning strength (Am), distribution width (σ2), upper critical field (Bc2) were determined so that a good fit was obtained between theoretical and experimental results. The Chittagong Univ. J. Sci. 42(1): 24-38, 2020

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30

Still, Holly, and Christina Hulbe. "Mechanics and dynamics of pinning points on the Shirase Coast, West Antarctica." Cryosphere 15, no. 6 (2021): 2647–65. http://dx.doi.org/10.5194/tc-15-2647-2021.

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Abstract. Ice rises and rumples, sites of localised ice-shelf grounding, modify ice-shelf flow by generating lateral and basal shear stresses, upstream compression, and downstream tension. Studies of pinning points typically quantify this role indirectly, through related metrics such as a buttressing number. Here, we quantify the dynamic effects of pinning points directly, by comparing model-simulated stress states in the Ross Ice Shelf (RIS) with and without a specific set of pinning points located downstream of the MacAyeal and Bindschadler ice streams (MacIS and BIS, respectively). Because ice properties are only known indirectly, the experiment is repeated with different realisations of the ice softness. While longitudinal stretching, and thus ice velocity, is smaller with the pinning points, flow resistance generated by other grounded features is also smaller. Conversely, flow resistance generated by other grounded features increases when the pinning points are absent, providing a non-local control on the net effect of the pinning points on ice-shelf flow. We find that an ice stream located directly upstream of the pinning points, MacIS, is less responsive to their removal than the obliquely oriented BIS. This response is due to zones of locally higher basal drag acting on MacIS, which may itself be a consequence of the coupled ice-shelf and ice-stream response to the pinning points. We also find that inversion of present-day flow and thickness for basal friction and ice softness, without feature-specific, a posteriori adjustment, leads to the incorrect representation of ice rumple morphology and an incorrect boundary condition at the ice base. Viewed from the perspective of change detection, we find that, following pinning point removal, the ice shelf undergoes an adjustment to a new steady state that involves an initial increase in ice speeds across the eastern ice shelf, followed by decaying flow speeds, as mass flux reduces thickness gradients in some areas and increases thickness gradients in others. Increases in ice-stream flow speeds persist with no further adjustment, even without sustained grounding-line retreat. Where pinning point effects are important, model tuning that respects their morphology is necessary to represent the system as a whole and inform interpretations of observed change.

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31

DEMIREL, ALI IHSAN. "PINNING MECHANISM AND FLUX MOTION IN YBa2Cu3O7 THIN FILMS." International Journal of Modern Physics B 18, no. 07 (2004): 999–1006. http://dx.doi.org/10.1142/s0217979204024434.

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The flux creep phenomena and the J c characteristics have been investigated in the YBa 2 Cu 3 O 7 (YBCO) thin films grown by metal organics chemical vapor deposition (MOCVD) technique. The anisotropy of the current density (J c ) is discussed on the basis of the intrinsic pinning model and the anisotropic critical magnetic field (H c2 ). The properties of the high J c and the pinning energy are related with the fine precipitates observed by tunneling electron microscopy (TEM). The strong pinning mechanism affects the amount of the flux motion.

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Aftalion, Amandine, Etienne Sandier, and Sylvia Serfaty. "Pinning phenomena in the Ginzburg–Landau model of superconductivity." Journal de Mathématiques Pures et Appliquées 80, no. 3 (2001): 339–72. http://dx.doi.org/10.1016/s0021-7824(00)01180-6.

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33

Nakashima, Makoto. "The free energy of the random walk pinning model." Stochastic Processes and their Applications 128, no. 2 (2018): 373–403. http://dx.doi.org/10.1016/j.spa.2017.04.015.

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34

Bergqvist, Anders. "Magnetic vector hysteresis model with dry friction-like pinning." Physica B: Condensed Matter 233, no. 4 (1997): 342–47. http://dx.doi.org/10.1016/s0921-4526(97)00319-0.

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35

Ikeda, Harukuni, and Kunimasa Miyazaki. "Fredrickson-Andersen model on Bethe lattice with random pinning." EPL (Europhysics Letters) 112, no. 1 (2015): 16001. http://dx.doi.org/10.1209/0295-5075/112/16001.

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36

Agassi, Y. D. "Low-field vortex pinning model for undoped sintered MgB2powders." Superconductor Science and Technology 24, no. 11 (2011): 115003. http://dx.doi.org/10.1088/0953-2048/24/11/115003.

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37

Sudo, Masato, Takeshi Mifune, Tetsuji Matsuo, and Chikara Kaido. "A Simplified Domain Structure Model Exhibiting the Pinning Field." IEEE Transactions on Magnetics 49, no. 5 (2013): 1829–32. http://dx.doi.org/10.1109/tmag.2013.2245313.

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38

Yang, Huizhong, and Li Sheng. "Pinning control of a generalized complex dynamical network model." Journal of Control Theory and Applications 7, no. 1 (2009): 1–8. http://dx.doi.org/10.1007/s11768-009-7214-3.

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39

Sosnowski, J. "New model of the pinning potential barrier in layered HTc superconductors." Modern Physics Letters B 30, no. 31 (2016): 1650387. http://dx.doi.org/10.1142/s0217984916503875.

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New model of the pinning potential barrier in multilayered HTc superconductors is presented, based on geometrical approach to the capturing interaction of pancake-type vortices with nano-sized defects. Using the above model the transport current flow phenomena in these materials, especially the current–voltage characteristics and critical current density, have been considered. Details of theoretical analysis are given, including the derivation of basic mathematical equations describing the potential barrier as a function of transport current intensity and the initial position of captured pancake vortex. Computer simulation has been performed of the influence of transport current amplitude on the potential barrier height for various sizes of pinning centers and initial pancake vortex position as well as the influence of fast neutrons irradiation creating nano-sized defects on critical current of HTc layered superconductor.

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40

Sosnowski, Jacek. "Impact of the Magnetic Flux Penetrating Vortex Core on the Critical Current of the HTc Superconductors." Materials Science Forum 670 (December 2010): 28–37. http://dx.doi.org/10.4028/www.scientific.net/msf.670.28.

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New model of the capturing vortices in the HTc superconductors is presented, describing their electromagnetic properties, such as the critical current of these materials. Critical current of the superconductors, such as HTc tapes is dependent on the magnitude of the interaction magnetic vortices with pinning centers. This is in fact quantum effect since the magnetic flux in vortices is quantized. Capturing the vortices on the normal state nano-sized inclusions should lead to the modification of the flux distribution in the vortex core depending on the vortex position in the respect to the pinning center edge. These effects are considered in the paper and their influence on the critical current of the HTc materials, basing on the new model of the pinning interaction.

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41

Muller, K.-H., JC Macfarlane, BW Ricketts, and R. Driver. "Role of Flux Pinning in High Temperature Superconductors." Australian Journal of Physics 42, no. 4 (1989): 413. http://dx.doi.org/10.1071/ph890413.

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The critical state model with a pinning force independent of flux density is employed to interpret the meas.ured ac magnetic flux response and the weak critical current density of ceramic Y-Ba-Cu-O material. The intergranular (Josephson) vortex pinning is found to be about 108 times weaker than that in conventional type II superconductors.

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42

CARTER, BRANDON, and ELIE CHACHOUA. "NEWTONIAN MECHANICS OF NEUTRON SUPERFLUID IN ELASTIC STAR CRUST." International Journal of Modern Physics D 15, no. 09 (2006): 1329–58. http://dx.doi.org/10.1142/s0218271806009145.

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To account for pulsar frequency glitches, it is necessary to use a neutron star crust model allowing not only for neutron superfluidity but also for elastic solidity. These features have been treated separately in previous treatments of crust matter, but are combined here in a unified treatment that is based on the use of a Lagrangian master functon, so that the system is ensured coherence by the relevant Noether identities. Besides the model obtained directly from the variation principle, the same master function can provide other conservative alternatives, allowing in particular for the effect of perfect vortex pinning. It is also shown how such models can be generalized to allow for dissipative effects, including that of imperfect pinning, meaning vortex drag or creep.

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POP, A. V. "AC MAGNETIC SUSCEPTIBILITY INVESTIGATION OF THE INTERGRAIN VORTEX PINNING INVOLVING Er IONS IN BULK (Bi1.6Pb0.4)(Sr1.8Ba0.2)(Ca1-xErx)2Cu3Oy SUPERCONDUCTOR." Modern Physics Letters B 14, no. 12 (2000): 447–53. http://dx.doi.org/10.1142/s0217984900000550.

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Bulk superconducting samples with composition ( Bi 1.6 Pb 0.4)( Sr 1.8 Ba 0.2)( Ca 1-x Er x)2 Cu 3 O y (0 ≤ x ≤ 0.02 Er ) were prepared by conventional solid-state reaction. X-ray diffraction confirmed that with increasing Er concentration, the volume fraction of 2223 phase decreases. The intergranular vortex dynamics (and the effective pinning barrier) of the bulk system have been investigated by ac susceptibility as a function of temperature, frequency and ac field amplitude. The effect of Er ion on the intergrain vortex pinning was characterized quantitatively by using a flux diffusion model in which the effective pinning barrier depends nonlinearly on the current density.

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44

CHEON, MOOKYUNG, and IKSOO CHANG. "THE ORDERING KINETICS OF ISING SPINS ON THE HONEYCOMB LATTICE." International Journal of Modern Physics C 15, no. 06 (2004): 835–43. http://dx.doi.org/10.1142/s0129183104006261.

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We investigate the coarsening dynamics of the Ising model on the honeycomb lattice by Monte Carlo simulation. Although the domain growth law and the persistence exponent at nonzero finite temperature are consistent with the known values of the two-dimensional (2D) Ising model on the square lattice, the nonequilibrium relaxation behavior of this model however shows the interesting and different relaxation properties of two-step relaxation due to the pinning effect and the slow activation process at a low temperature. Multispin heat bath dynamics is used to remove such a pinning effect, which results in the same relaxation behavior of the 2D Ising model as on the square lattice.

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45

Thompson, G. S., J. M. Rickman, M. P. Harmer, and E. A. Holm. "The effects of particle size distribution and induced unpinning during grain growth." Journal of Materials Research 11, no. 6 (1996): 1520–27. http://dx.doi.org/10.1557/jmr.1996.0190.

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The effect of a second-phase particle size distribution on grain boundary pinning was studied using a Monte Carlo simulation technique. Simulations were run using a constant number density of both whisker and rhombohedral particles, and the effect of size distribution was studied by varying the standard deviation of the distribution around a constant mean particle size. The results of present simulations indicate that, in accordance with the stereological assumption of the topological pinning model, changes in distribution width had no effect on the pinned grain size. The effect of induced unpinning of particles on microstructure was also studied. In contrast to predictions of the topological pinning model, a power law dependence of pinned grain size on particle size was observed at T = 0.0. Based on this, a systematic deviation to the stereological predictions of the topological pinning model is observed. The results of simulations at higher temperatures indicate an increasing power law dependence of pinned grain size on particle size, with the slopes of the power law dependencies fitting an Arrhenius relation. The effect of induced unpinning of particles was also studied in order to obtain a correlation between particle/boundary concentration and equilibrium grain size. The results of simulations containing a constant number density of monosized rhombohedral particles suggest a strong power law correlation between the two parameters.

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46

Fujiyama, Naoto, and Akira Seki. "Austenite Grain Growth Simulation in Welding Heat-Affected Zone." Materials Science Forum 941 (December 2018): 620–26. http://dx.doi.org/10.4028/www.scientific.net/msf.941.620.

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To predict austenite grain growth behavior in the heat-affected zone (HAZ) in low alloy steels, a new calculation model is proposed herein. This model mainly considers the solute-drag effect and pinning effect, which restrain the austenite grain growth. To calculate the solute-drag effect, the grain boundary concentration of each element is obtained by Hillert’s Law. Calculations are performed by simulating the HAZ with a temperature gradient using the phase field method for two dimensions. This calculation demonstrates the possibility of quantitatively predicting the pinning force for welding heat inputs.

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47

Favier, L., O. Gagliardini, G. Durand, and T. Zwinger. "A three-dimensional full Stokes model of the grounding line dynamics: effect of a pinning point beneath the ice shelf." Cryosphere 6, no. 1 (2012): 101–12. http://dx.doi.org/10.5194/tc-6-101-2012.

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Abstract. The West Antarctic ice sheet is confined by a large area of ice shelves, fed by inland ice through fast flowing ice streams. The dynamics of the grounding line, which is the line-boundary between grounded ice and the downstream ice shelf, has a major influence on the dynamics of the whole ice sheet. However, most ice sheet models use simplifications of the flow equations, as they do not include all the stress components, and are known to fail in their representation of the grounding line dynamics. Here, we present a 3-D full Stokes model of a marine ice sheet, in which the flow problem is coupled with the evolution of the upper and lower free surfaces, and the position of the grounding line is determined by solving a contact problem between the shelf/sheet lower surface and the bedrock. Simulations are performed using the open-source finite-element code Elmer/Ice within a parallel environment. The model's ability to cope with a curved grounding line and the effect of a pinning point beneath the ice shelf are investigated through prognostic simulations. Starting from a steady state, the sea level is slightly decreased to create a contact point between a seamount and the ice shelf. The model predicts a dramatic decrease of the shelf velocities, leading to an advance of the grounding line until both grounded zones merge together, during which an ice rumple forms above the contact area at the pinning point. Finally, we show that once the contact is created, increasing the sea level to its initial value does not release the pinning point and has no effect on the ice dynamics, indicating a stabilising effect of pinning points.

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48

Favier, L., O. Gagliardini, G. Durand, and T. Zwinger. "A three-dimensional full Stokes model of the grounding line dynamics: effect of a pinning point beneath the ice shelf." Cryosphere Discussions 5, no. 4 (2011): 1995–2033. http://dx.doi.org/10.5194/tcd-5-1995-2011.

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Abstract. The West Antarctic ice sheet is confined by a large area of ice shelves, fed by inland ice through fast flowing ice streams. The dynamics of the grounding line, i.e. the line-boundary between grounded ice and the downstream ice shelf, has a major influence on the dynamics of the whole ice sheet. However, most of the ice sheet models use simplifications of the flow equations, i.e., they do not include all the stress components, and are known to fail in their mathematical representation of the grounding line dynamics. Here, we present a 3-D full Stokes model of a marine ice sheet, in which the flow problem is coupled with the evolution of the upper and lower free surfaces, and the position of the grounding line determined by solving a contact problem between the shelf/sheet lower surface and the bedrock. Simulations are performed using the open-source finite-element code Elmer/Ice within a parallel environment. The effect of a pinning point, inserted beneath the ice shelf, on the ice dynamics is studied to demonstrate the model's ability to cope with curved and multiple grounding lines. Starting from a steady state, the sea level is slightly decreased to create a contact point between a seamount and the ice shelf. The model predicts a dramatic decrease of the shelf velocities, leading to an advance of the grounding line until both grounded zones merge together, during which an ice rumple forms above the contact area at the pinning point. Finally, we show that once the contact is created, increasing the sea level to its initial value does not cease the interaction with the pinning point and has no effect on the ice dynamics, indicating a stabilizing effect of pinning points.

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49

Couturier, G., Claire Maurice, R. Fortunier, R. Doherty, and Julian H. Driver. "Finite Element Simulations of 3D Zener Pinning." Materials Science Forum 467-470 (October 2004): 1009–18. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.1009.

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An original model, based on a variational formulation for boundary motion by viscous drag, is developed to simulate single grain boundary motion and its interaction with particles. The equations are solved by a 3D finite element method to obtain the instantaneous velocity at each triangular element on the boundary surface, before, during and after contact with one or more particles. After validation by comparison with some simple, analytical and numerical cases, it is adapted to model curvature driven grain growth. For single phase material, the single grain boundary model closely matches the grain coarsening kinetics of a 3D multi boundary vertex model. In the presence of spherical incoherent particles the growth rate slows down to give a growth exponent of 2.5. When the boundary is anchored there is a significantly higher density, by a factor of 4, of particles on the boundary than the density predicted by the classic Zener analysis, and many particles exert less than this Zener drag force. As a result the Zener drag is increased by a factor of about 2.2. The limiting grain radius is compared with some experimental results.

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Miroux, A., Zacharias J. Lok, and Sybrand van der Zwaag. "Recrystallisation and Concurrent Precipitation in Hot Rolled AA3103." Materials Science Forum 467-470 (October 2004): 393–98. http://dx.doi.org/10.4028/www.scientific.net/msf.467-470.393.

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The recrystallisation kinetics experimentally measured on a supersaturated AA3103 after hot rolling is analysed using a numerical model. It is shown that temperature and nucleation inhibition due to precipitation on the subgrain structure are the two most important parameters in controlling the recrystallisation kinetics. On the opposite, particle pinning of recrystallised grain boundaries is negligible while pinning of subgrain boundaries during recovery and solute drag are relevant but second order effects.

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Journal articles on the topic 'Pinning model'

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