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Articoli di riviste sul tema "Energies surface anisotropie"

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Autore: Grafiati
Pubblicato: 1 giugno 2024

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1

Vidyasagar, A., S. Krödel e D. M. Kochmann. "Microstructural patterns with tunable mechanical anisotropy obtained by simulating anisotropic spinodal decomposition". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, n. 2218 (ottobre 2018): 20180535. http://dx.doi.org/10.1098/rspa.2018.0535.

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The generation of mechanical metamaterials with tailored effective properties through carefully engineered microstructures requires avenues to predict optimal microstructural architectures. Phase separation in heterogeneous systems naturally produces complex microstructural patterns whose effective response depends on the underlying process of spinodal decomposition. During this process, anisotropy may arise due to advection, diffusive chemical gradients or crystallographic interface energy, leading to anisotropic patterns with strongly directional effective properties. We explore the link between anisotropic surface energies during spinodal decomposition, the resulting microstructures and, ultimately, the anisotropic elastic moduli of the resulting medium. We simulate the formation of anisotropic patterns within representative volume elements, using recently developed stabilized spectral techniques that circumvent further regularization, and present a powerful alternative to current numerical techniques. The interface morphology of representative phase-separated microstructures is shown to strongly depend on surface anisotropy. The effective elastic moduli of the thus-obtained porous media are identified by periodic homogenization, and directionality is demonstrated through elastic surfaces. Our approach not only improves upon numerical tools to simulate phase separation; it also offers an avenue to generate tailored microstructures with tunable resulting elastic anisotropy.
2

SCHMIDT, W. G., J. L. FATTEBERT, J. BERNHOLC e F. BECHSTEDT. "SELF-ENERGY EFFECTS IN THE OPTICAL ANISOTROPY OF GaP(001)". Surface Review and Letters 06, n. 06 (dicembre 1999): 1159–65. http://dx.doi.org/10.1142/s0218625x99001281.

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We calculate the reflectance anisotropy for GaP(001)(2×4) surfaces using a real-space multigrid method and ab initio pseudopotentials. Our results obtained within DFT-LDA show good qualitative agreement with recent experiments. This holds in particular for the stoichiometric trends. A strong negative anisotropy at low photon energies is linked to the formation of Ga–Ga bonds along the [110] direction. There are discrepancies, however, with respect to the line shape and the energetic positions of characteristic peaks. Substantial improvement is achieved by using a numerically efficient GW approach with approximations for local-field effects and dynamical screening. We find that the spectral features related to transitions between surface perturbed bulk wave functions are more strongly affected by self-energy corrections than anisotropies directly linked to surface electronic states.
3

Kido, Eiji. "Current status of the TAx4 surface detectors". EPJ Web of Conferences 283 (2023): 06003. http://dx.doi.org/10.1051/epjconf/202328306003.

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Telescope Array (TA) is the largest ultrahigh-energy cosmic-ray (UHECR) observatory in the northern hemisphere. It explores the origin of UHECRs using a surface detector (SD) array, covering approximately 700 km2, and a fluorescence detector (FD) stations viewing the skies above the array. TA has found evidence for a cluster of cosmic rays with energies greater than 57 EeV known as a HotSpot. Recently, TA has obtained additional evidence for an excess of cosmic rays with energies above 1019.4 eV and also found implications of spectrum anisotropy. An expanded SD array and FD stations called TAx4 experiment was designed to increase the data collection rate at the highest energies to confirm the anisotropies with more data. We have constructed and deployed more than half of the SDs for the TAx4 experiment and began stable data taking operations. We present TAx4 SD’s current status.
4

HE, L., Y. W. LIU, W. J. TONG, J. G. LIN e X. F. WANG. "SURFACE ENERGY ENGINEERING OF Cu SURFACE BY STRAIN: FIRST-PRINCIPLES CALCULATIONS". Surface Review and Letters 20, n. 06 (dicembre 2013): 1350054. http://dx.doi.org/10.1142/s0218625x13500546.

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Surface energies of strained Cu surfaces were studied systematically using first-principles methods. Results showed that the strain-stabilization of Cu surface was anisotropic and strongly related to the strain distribution. This strain-induced approach could be used as an effective way to engineer the surface energies of metals.
5

Filimonov, Sergey N. "Ab Initio Calculations of Absolute Surface Energies of Clean and Hydrogen Covered 3C-SiC(001), (110) and (111) Surfaces". Materials Science Forum 821-823 (giugno 2015): 363–66. http://dx.doi.org/10.4028/www.scientific.net/msf.821-823.363.

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The absolute surface energies of three major low index surfaces of cubic silicon carbide (3C-SiC) are determined by first-principles density functional theory calculations. Calculations show that among clean 3C-SiC surfaces the Si-terminated 3C-SiC(001)-(3x2) surface has the lowest energy. The second and third lowest energy surfaces are the Si-terminated 3C-SiC(111)-(√3x√3) surface and the nonreconstructed 3C-SiC(110) surface. Hydrogen passivation greatly reduces both the absolute surface energies of the low index 3C-SiC surfaces and the surface energy anisotropy. In particular, the surface energies of fully passivated 3C-SiC(110) and (111) surfaces become indistinguishable at hydrogen-rich deposition conditions.
6

Семина, М. А., А. А. Головатенко, Т. В. Шубина e А. В. Родина. "Локализация носителей в квантовых точках с одноосной анизотропией формы и состава". Физика твердого тела 61, n. 4 (2019): 636. http://dx.doi.org/10.21883/ftt.2019.04.47405.335.

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AbstractThe electronic and hole states in quantum dots (QD) of cubic II–VI semiconductors with a spheroidal shape and uniaxial anisotropy have been studied theoretically. The smooth potential energy profiles simulated by the Gauss function in all three spatial directions are considered. The energy level lowering and the energy splitting of the hole state from the valence band top Γ_8 by momentum 3/2 into the states with projections ±3/2, ±1/2 on the anisotropy axis are analyzed. The QD anisotropies of three types are considered: the QD size anisotropy, the QD potential barrier anisotropy, and the combined anisotropy. In the first case, flattened quantum dots, in which the characteristic size in the structure plane is larger than the size along the anisotropy axis, are considered. In the second case, QDs, in which the potential barrier height in the plane is lower than that along the anisotropy axis, are considered. In the third case, flattened quantum dots with the anisotropy of the size and the potential barrier are considered. The conditions of the charge carrier localization inside QD have been found, and the influence of the form and composition anisotropies on the energies of exciton transitions in the structures with Cd_ x Zn_1 – _ x Se quantum dots are discussed.
7

Palmer, Bennett. "Stable closed equilibria for anisotropic surface energies: Surfaces with edges". Journal of Geometric Mechanics 4, n. 1 (2012): 89–97. http://dx.doi.org/10.3934/jgm.2012.4.89.

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8

Suomijärvi, T. "The AugerPrime upgrade of the Pierre Auger Observatory". Journal of Physics: Conference Series 2429, n. 1 (1 febbraio 2023): 012010. http://dx.doi.org/10.1088/1742-6596/2429/1/012010.

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Abstract Operating since 2004, the Pierre Auger Observatory has yielded several important results. The suppression of the flux around 5×1019 eV is now confirmed without any doubt, a large-scale dipole anisotropy has been found for energies above 8×1018 eV, as well as an indication for some intermediate-scale anisotropy at the highest energies. Furthermore, strong limits have been placed on ultra-high-energy photons and neutrinos. In order to elucidate the origin of the flux suppression at the highest energies and search for composition-enhanced anisotropies, the Auger Collaboration is currently upgrading the Observatory. In the framework of the upgrade, called AugerPrime, the array of 1660 water-Cherenkov detectors is equipped with plastic scintillators, allowing us to enhance the composition sensitivity. The station electronics is also upgraded, including better timing with up-to-date GPS receivers, higher sampling frequency, and increased dynamic range. Currently, more than 40% of the surface detectors have been upgraded, and the commissioning studies are well advanced. In this paper, the design of the AugerPrime surface detectors will be presented, and the performance obtained from the analysis of the first data will be discussed.
9

Elsey, Matt, e Selim Esedoḡlu. "Threshold dynamics for anisotropic surface energies". Mathematics of Computation 87, n. 312 (19 ottobre 2017): 1721–56. http://dx.doi.org/10.1090/mcom/3268.

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10

Stinner, Björn. "Multi-phase field systems with anisotropic surface energies". PAMM 7, n. 1 (dicembre 2007): 1150101–2. http://dx.doi.org/10.1002/pamm.200700476.

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11

Bonzel, H. P., e K. Dückers. "Correlation between anisotropies of surface energies and surface core level shifts". Surface Science 184, n. 3 (giugno 1987): 425–33. http://dx.doi.org/10.1016/s0039-6028(87)80367-9.

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12

Bonzel, H. P., e K. Dückers. "Correlation between anisotropies of surface energies and surface core level shifts". Surface Science Letters 184, n. 3 (giugno 1987): A217. http://dx.doi.org/10.1016/0167-2584(87)90355-0.

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13

Francis, Andrew J., e Paul A. Salvador. "Crystal orientation and surface morphology of face-centered-cubic metal thin films deposited upon single-crystal ceramic substrates using pulsed laser deposition". Journal of Materials Research 22, n. 1 (gennaio 2007): 89–102. http://dx.doi.org/10.1557/jmr.2007.0014.

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Cu, Pt, Ag, and Au were deposited on (100)-oriented ceramic substrates (SrTiO3, LaAlO3, and MgO). Over a wide range of temperatures (room temperature to 600 °C), Cu films were (100)-oriented and exhibited cube-on-cube epitaxy. Epitaxial Pt(100) films were obtained only at high temperature; oriented Pt(111) films were obtained at lower temperatures. Ag and Au were never obtained as purely (100)-oriented samples, although the amount of (100)-film increased with increasing temperature. Three-dimensional islands formed for all metals at higher temperatures, while flatter film surfaces developed at lower temperatures. At any given temperature, the surface roughness of films on SrTiO3(100) increased in the order Pt < Cu < Au < Ag. The variations in film structural characteristics are described well by considering the metals’ (i) surface/interfacial energies, (ii) surface energy anisotropies, and (iii) surface diffusion coefficients. Flat, epitaxial growth is promoted by low-energy interfaces, low surface energy anisotropies, and slow surface diffusion.
14

Fonseca, Irene, Nicola Fusco, Giovanni Leoni e Vincent Millot. "Material voids in elastic solids with anisotropic surface energies". Journal de Mathématiques Pures et Appliquées 96, n. 6 (dicembre 2011): 591–639. http://dx.doi.org/10.1016/j.matpur.2011.07.003.

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15

Hu, Yuehua, Zhiyong Gao, Wei Sun e Xiaowen Liu. "Anisotropic surface energies and adsorption behaviors of scheelite crystal". Colloids and Surfaces A: Physicochemical and Engineering Aspects 415 (dicembre 2012): 439–48. http://dx.doi.org/10.1016/j.colsurfa.2012.09.038.

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16

Zhang, W., P. Sachenko e I. Gladwell. "Thermal grain boundary grooving with anisotropic surface free energies". Acta Materialia 52, n. 1 (gennaio 2004): 107–16. http://dx.doi.org/10.1016/j.actamat.2003.08.033.

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17

Mamonova M. V., Makeev M. Y., Kalinin D. S. e Zenova A. A. "First-principle calculations of the magnetic anisotropy of Fe and Co films separated by an interlayer of non-magnetic metals". Physics of the Solid State 63, n. 13 (2022): 1653. http://dx.doi.org/10.21883/pss.2022.13.52072.03s.

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This paper presents the results of numerical calculations of the magnetic characteristics of Co and Fe monolayer films on Cu and Pt surfaces using the VASP software package. The values of the difference between the total energies of the antiferromagnetic and ferromagnetic configurations are calculated depending on the convergence parameters and the thickness of the nonmagnetic material. The values of the magnetic anisotropy and magnetic moment of atoms in the structures of Co/Cu/Co, Fe/Pt/Fe, Co/Pt/Co, Pt/Co/Cu/Co/Pt are determined depending on the orientation of the surface face. For the (110) and (111) faces, the phenomenon of reorientation in the Co/Cu/Co structure is confirmed, when the anisotropy of the cobalt films parallel to the surface plane is replaced by the perpendicular anisotropy due to the introduction of an ultrathin platinum film into the structure. Keywords: Magnetic anisotropy, ultrathin magnetic films.
18

Шеин, И. Р. "Механическая и динамическая стабильность комплектного и нестехиометрического 3C-Si-=SUB=-x-=/SUB=-C-=SUB=-y-=/SUB=- из ab initio расчетов". Физика твердого тела 60, n. 10 (2018): 1969. http://dx.doi.org/10.21883/ftt.2018.10.46525.090.

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AbstractThe energies of formation of vacancies in the carbon and silicon sublattices, the independent elastic constants, the all-round compression, shear and Young’s moduli, and the anisotropy coefficients are determined for the complete and nonstoichiometric cubic phases of 3 C -Si_ x C_ y ( x , y = 1.0–0.75) by ab initio methods of the band theory. In the formalism of the density functional perturbation theory (DFPT), the phonon dispersion dependences are obtained for these phases (the comparison with the experiment is given for the complete phase). It is shown that the mechanical characteristics of the phases become strongly anisotropic upon the transition from 3 C -SiC_0.875 to 3 C -SiC_0.75. It is established from the analysis of the phonon dispersion curves that the 3 C -SiC_0.875 and 3 C -SiC_0.75 phases, in contrast to the complete 3 C -SiC phase, are dynamically unstable at T = 0 K.
19

Мамонова, М. В., М. Ю. Макеев, Д. С. Калинин e А. А. Зенова. "Первопринципные расчеты магнитной анизотропии пленок Fe и Co, разделенных прослойкой немагнитных металлов". Физика твердого тела 63, n. 11 (2021): 1787. http://dx.doi.org/10.21883/ftt.2021.11.51577.03s.

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This paper presents the results of numerical calculations of the magnetic characteristics of Co and Fe monolayer films on Cu and Pt surfaces using the VASP software package. The values ​​of the difference between the total energies of the antiferromagnetic and ferromagnetic configurations are calculated depending on the convergence parameters and the thickness of the nonmagnetic material. The values ​​of the magnetic anisotropy and magnetic moment of atoms in the structures of Co / Cu / Co, Fe / Pt / Fe, Co / Pt / Co, Pt / Co / Cu / Co / Pt are determined depending on the orientation of the surface face. For the (110) and (111) faces, the phenomenon of reorientation in the Co / Cu / Co structure is confirmed, when the anisotropy of the cobalt films parallel to the surface plane is replaced by the perpendicular anisotropy due to the introduction of an ultrathin platinum film into the structure.
20

Bonacini, Marco. "Epitaxially strained elastic films: the case of anisotropic surface energies". ESAIM: Control, Optimisation and Calculus of Variations 19, n. 1 (1 marzo 2012): 167–89. http://dx.doi.org/10.1051/cocv/2012003.

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21

Searcy, Alan W. "Driving Force for Sintering of Particles with Anisotropic Surface Energies". Journal of the American Ceramic Society 68, n. 10 (ottobre 1985): C—267—C—268. http://dx.doi.org/10.1111/j.1151-2916.1985.tb11526.x.

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22

Koiso, Miyuki, e Bennett Palmer. "Equilibria for anisotropic surface energies with wetting and line tension". Calculus of Variations and Partial Differential Equations 43, n. 3-4 (21 aprile 2011): 555–87. http://dx.doi.org/10.1007/s00526-011-0423-x.

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23

Min, Donghong, e Harris Wong. "Grain-boundary grooving by surface diffusion with asymmetric and strongly anisotropic surface energies". Journal of Applied Physics 99, n. 2 (15 gennaio 2006): 023515. http://dx.doi.org/10.1063/1.2159082.

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24

Floro, J. A., C. V. Thompson, R. Carel e P. D. Bristowe. "Competition between strain and interface energy during epitaxial grain growth in Ag films on Ni(001)". Journal of Materials Research 9, n. 9 (settembre 1994): 2411–24. http://dx.doi.org/10.1557/jmr.1994.2411.

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Epitaxial Grain Growth (EGG) is an orientation-selective process that can occur in polycrystalline thin films on single crystal substrates. EGG is driven by minimization of crystallographically anisotropic free energies. One common driving force for EGG is the reduction of the film/substrate interfacial energy. We have carried out experiments on polycrystalline Ag films on Ni(001) substrates. The orientation dependence of the Ag/Ni interfacial energy has been previously calculated using the embedded atom method. Under some conditions, EGG experiments lead to the (111) orientations calculated to be interface- and surface-energy-minimizing. However, when Ag films are deposited on Ni(001) at low temperature, EGG experiments consistently find that (111) oriented grains are consumed by grains with (001) orientations predicted to have much higher interface and surface energy. The large elastic anisotropy of Ag can account for this discrepancy. Strain energy minimization favors growth of (001) grains and can supersede minimization of interfacial energy if sufficient strain is present and if the film is initially unable to relieve the strain by plastic deformation.
25

Zhang, Wen, e Ian Gladwell. "Evolution of two-dimensional crystal morphologies by surface diffusion with anisotropic surface free energies". Computational Materials Science 27, n. 4 (giugno 2003): 461–70. http://dx.doi.org/10.1016/s0927-0256(03)00047-8.

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26

Ramamurthy, Sundar, Brian C. Hebert e C. Barry Carter. "Non-equilibrium silicate glass in contact with faceted {1010} α-Al2O3 surface: a SEM study". Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 agosto 1995): 340–41. http://dx.doi.org/10.1017/s0424820100138075.

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Perhaps the most striking feature about α-A12O3 lies in the anisotropy of its crystal structure. Surface energies, γ, (relaxed and unrelaxed) have been theoretically calculated for different low-index planes in alumina. As an example to illustrate the anisotropy, the reported values of γ for two unrelaxed planes ( {100} and {102} ) vary by a factor of about 2 while the factor is only about 15% between {110} and {111} planes in a fcc metal. Among the low-index planes in α-Al2O3, the {100} plane has been reported to have the largest value of γ. Experimental observations of heat-treated {100} surfaces indicate a breakdown of the surface into an array of facets containing inclined steps. This faceting behavior has also been observed when the surface is in contact with calcium aluminosilicate glass at 1600°C. The {100} surface was found to be replaced by two sets of facets parallel to the {101} and {102} planes respectively. In that study the glass was a near-anorthite (CaAl2Si2O8) composition which is in equilibrium with A12O3 at 1600°C in air.
27

Yue, Jeffrey, Xu Chuan Jiang e Ai Bing Yu. "Theoretical Study of Growth Mechanism of Goethite in the Presence of Surfactants". Materials Science Forum 654-656 (giugno 2010): 1658–61. http://dx.doi.org/10.4028/www.scientific.net/msf.654-656.1658.

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Goethite (α-FeOOH) nanorods could be prepared by a surfactant directed approach in aqueous solution at ambient conditions. In this approach, it is observed that the surfactants (e.g, cetyltrimethylammonium bromide (CTAB) and tetraethylamine chloride (TEAC)) play a key role in the growth of goethite nanorods under the reported conditions. The molecular dynamics (MD) method is used to understand the underlying principle governing particle formation and growth through the analysis of the interaction energies between the crystal surfaces and the surfactant molecules. The findings will be useful for understanding the growth mechanism of anisotropic particles and their surface coatings with heterogeneous materials for desired functional properties.
28

Abbarchi, Marco, Takaaki Mano, Takashi Kuroda, Akihiro Ohtake e Kazuaki Sakoda. "Polarization Anisotropies in Strain-Free, Asymmetric, and Symmetric Quantum Dots Grown by Droplet Epitaxy". Nanomaterials 11, n. 2 (10 febbraio 2021): 443. http://dx.doi.org/10.3390/nano11020443.

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We provide an extensive and systematic investigation of exciton dynamics in droplet epitaxial quantum dots comparing the cases of (311)A, (001), and (111)A surfaces. Despite a similar s-shell exciton structure common to the three cases, the absence of a wetting layer for (311)A and (111)A samples leads to a larger carrier confinement compared to (001), where a wetting layer is present. This leads to a more pronounced dependence of the binding energies of s-shell excitons on the quantum dot size and to the strong anti-binding character of the positive-charged exciton for smaller quantum dots. In-plane geometrical anisotropies of (311)A and (001) quantum dots lead to a large electron-hole fine interaction (fine structure splitting (FSS) ∼100 μeV), whereas for the three-fold symmetric (111)A counterpart, this figure of merit is reduced by about one order of magnitude. In all these cases, we do not observe any size dependence of the fine structure splitting. Heavy-hole/light-hole mixing is present in all the studied cases, leading to a broad spread of linear polarization anisotropy (from 0 up to about 50%) irrespective of surface orientation (symmetry of the confinement), fine structure splitting, and nanostructure size. These results are important for the further development of ideal single and entangled photon sources based on semiconductor quantum dots.
29

BARRETT, JOHN W., HARALD GARCKE e ROBERT NÜRNBERG. "Finite-element approximation of coupled surface and grain boundary motion with applications to thermal grooving and sintering". European Journal of Applied Mathematics 21, n. 6 (21 luglio 2010): 519–56. http://dx.doi.org/10.1017/s0956792510000203.

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We study the coupled surface and grain boundary motion in bi- and tricrystals in three-space dimensions, building on previous work by the authors on the simplified two-dimensional case. The motion of the interfaces, which in this paper are presented by two-dimensional hypersurfaces, is described by two types of normal velocities: motion by mean curvature and motion by surface diffusion. Three hypersurfaces meet at triple-junction lines, where junction conditions need to hold. Similarly, boundary conditions are prescribed where an interface meets an external boundary, and these conditions naturally give rise to contact angles. We present a variational formulation of the flows, which leads to a fully practical finite-element approximation that exhibits excellent mesh properties, with no mesh smoothing or remeshing required in practice. For the introduced parametric finite-element approximation we show well posedness and, in general, unconditional stability, i.e. there is no restriction on the chosen time-step size. Moreover, the induced discrete equations are linear and easy to solve. A generalisation to anisotropic surface energies is straightforward. Several numerical results in two- and three-space dimensions are presented, including simulations for thermal grooving and sintering. Three-dimensional simulations featuring quadruple junction points, non-standard boundary contact angles and fully anisotropic surface energies are also presented.
30

ZHOU, CHUNFENG, PENGTAO YUE e JAMES J. FENG. "The rise of Newtonian drops in a nematic liquid crystal". Journal of Fluid Mechanics 593 (23 novembre 2007): 385–404. http://dx.doi.org/10.1017/s0022112007008889.

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We simulate the rise of Newtonian drops in a nematic liquid crystal parallel to the far-field molecular orientation. The moving interface is computed in a diffuse-interface framework, and the anisotropic rheology of the liquid crystal is represented by the Leslie–Ericksen theory, regularized to permit topological defects. Results reveal interesting coupling between the flow field and the orientational field surrounding the drop, especially the defect configuration. The flow generally sweeps the point and ring defects downstream, and may transform a ring defect into a point defect. The stability of these defects and their transformation are depicted in a phase diagram in terms of the Ericksen number and the ratio between surface anchoring and bulk elastic energies. The nematic orientation affects the flow field in return. Drops with planar anchoring on the surface rise faster than those with homeotropic anchoring, and the former features a vortex ring in the wake. These are attributed to the viscous anisotropy of the nematic. With homeotropic anchoring, the drop rising velocity experiences an overshoot, owing to the transformation of the initial surface ring defect to a satellite point defect. With both types of anchoring, the drag coefficient of the drop decreases with increasing Ericksen number as the flow-alignment of the nematic orientation reduces the effective viscosity of the liquid crystal.
31

Baxter, Rodney J. "The bulk, surface and corner free energies of the anisotropic triangular Ising model". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 476, n. 2234 (febbraio 2020): 20190713. http://dx.doi.org/10.1098/rspa.2019.0713.

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We consider the anisotropic Ising model on the triangular lattice with finite boundaries, and use Kaufman’s spinor method to calculate low-temperature series expansions for the partition function to high order. From these, we can obtain 108-term series expansions for the bulk, surface and corner free energies. We extrapolate these to all terms and thereby conjecture the exact results for each. Our results agree with the exactly known bulk-free energy and with Cardy and Peschel’s conformal invariance predictions for the dominant behaviour at criticality. For the isotropic case, they also agree with Vernier and Jacobsen’s conjecture for the 60 ° corners.
32

SOHEYLI, S., H. NOSHAD e M. LAMEHI-RACHTI. "MEASUREMENT OF FISSION FRAGMENT ANISOTROPIES FOR PROTON-INDUCED FISSION OF TWO PRE-ACTINIDE NUCLEI AT SEVERAL ENERGIES". International Journal of Modern Physics A 22, n. 05 (20 febbraio 2007): 1027–37. http://dx.doi.org/10.1142/s0217751x07034428.

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The angular distribution of fission fragments has been measured for proton-induced fission of 197 Au and 209 Bi nuclei at several energies between 25 and 30 MeV using surface-barrier detectors. The measured anisotropies are found to be in agreement with the predictions of the standard saddle-point statistical model. The measured anisotropies for neither of the nuclei show any anomalous behavior as a function of both energy and entrance channel mass asymmetry. The fission cross sections of 197 Au and 209 Bi nuclei were also measured and compared with that of the previous works.
33

AL, Selgin. "Investigations of Physical Properties of XTiH3 and Implications for Solid State Hydrogen Storage". Zeitschrift für Naturforschung A 74, n. 11 (26 novembre 2019): 1023–30. http://dx.doi.org/10.1515/zna-2019-0184.

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AbstractThis study adopts density functional theory to predict and thoroughly investigate new types of perovskite compounds for solid state storage of hydrogen. CaTiH3 and MgTiH3 perovskite hydrides are chosen and investigated using density functional theory in terms of ground state properties, electronic, mechanical, and thermodynamic properties for solid state storage of hydrogen. Stability of compounds are verified by calculating formation energies. Several crucial parameters; elastic constants, bulk, Young, Shear modulus, and Cauchy pressures are computed and analysed in great detail. Mechanical stability evaluation indicated that both compounds are mechanically stable whereas MgTiH3 is ductile whilst CaTiH3 is a brittle material. In addition, mechanical anisotropy is analysed using 2D surfaces. Both compounds showed anisotropic behaviour in all directions except for linear compressibility. Electronic band structures and their corresponding density of states of compounds are obtained. The results indicate that both compounds have metallic nature. From the results presented here, it can be predicted that MgTiH3 is a better material for hydrogen storage with a gravimetric density of ∼4.01 wt %.
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Lisunova, Milana O. "Assembly Controlled by Shape". MRS Advances 4, n. 22 (14 novembre 2018): 1261–65. http://dx.doi.org/10.1557/adv.2018.606.

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ABSTRACTTo research the impact of the shape on the assembly of the natural objects (protein, virus, bacteria, living cells) the polymer microcapsules with similar surface chemistry and different by shape (spherical, cubical and tetrahedral) had been synthesized. It was found that the energetically favourable face-to-face attachment of anisotropic microcapsules drives the formation of stable and compacted assembly while isotropic microcapsules assembly is mobile and chain-like structures with a point like a contact area. The difference in assembling behaviour of anisotropic (cubic, tetrahedral) and isotropic (spherical) microparticles is related to the fact that the interfacial hydrophobic energies between the anisotropic microparticles are 6-4 orders of magnitude higher than that for the isotropic microparticles due to the significantly higher contact area of anisotropic microparticles. Such mimicking of the natural objects by polymer microcapsules and research their interaction driven by shape explains the arrangements of isotropic and anisotropic cells in bacteria and its mobility.
35

Lai, Chang Quan, Carl V. Thompson e Wee Kiong Choi. "Uni-, Bi-, and Tri-Directional Wetting Caused by Nanostructures with Anisotropic Surface Energies". Langmuir 28, n. 30 (16 luglio 2012): 11048–55. http://dx.doi.org/10.1021/la301956q.

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Kim, Jihyun, Dmitri Ivanov, Kazumasa Kawata, Hiroyuki Sagawa e Gordon Thomson. "Updates on the Hotspot and the Perseus-Pisces supercluster Excess Observed by the Telescope Array Experiment". EPJ Web of Conferences 283 (2023): 03005. http://dx.doi.org/10.1051/epjconf/202328303005.

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The Telescope Array (TA) experiment, the largest observatory studying ultra-high energy cosmic rays in the northern hemisphere, has reported evidence for two medium-scale anisotropies. The first, known as the TA hotspot, is an excess in the arrival direction distribution for events with energies greater than 5.7 × 1019 eV. More recently, an additional excess of events with energies greater than 1019.4 eV appearing in the direction of the Perseus-Pisces supercluster has been named the PPSC excess. In this presentation, we will update the status of the TA hotspot and the PPSC excess results using the most recent data measured by the TA surface detector array.
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Huang, Weicong, Hu Shi, Hongguang Liu e Clémence Corminboeuf. "The influence of external electric fields on charge reorganization energy in organic semiconductors". Chemical Communications 55, n. 16 (2019): 2384–87. http://dx.doi.org/10.1039/c8cc09680e.

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BARTOŠ, I., e W. SCHATTKE. "SURFACE SENSITIVITY OF VERY LOW ENERGY ELECTRONS". Surface Review and Letters 06, n. 05 (ottobre 1999): 631–33. http://dx.doi.org/10.1142/s0218625x99000603.

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The surface sensitivity of electron diffraction and of electron spectroscopies is determined by the imaginary component of the electron self-energy. In crystals, the energy and direction dependence of the electron attenuation and of the escape depth should be taken into account at very low energies. Strong anisotropy of the electron attenuation has been obtained around 20 eV from peak shapes in VLEED intensity profiles from (111) transition metal surfaces. Extension of the local density approximation in the density functional formalism provides quantitative description of the electron self-energy. The one-step model of angular resolved photoemission incorporating the self-energy predicts a strong energy and angle dependence of the escape depth of low energy photoelectrons emitted from GaAs(110).
39

Суетин, Д. В. "Структурные, упругие, электронные свойства и межатомные взаимодействия серии металлических тетраборидов MB-=SUB=-4-=/SUB=- (M=Ru, Rh, Pd, Os, Ir, Pt), полученные из FLAPW-GGA-расчетов". Физика твердого тела 61, n. 1 (2019): 22. http://dx.doi.org/10.21883/ftt.2019.01.46890.185.

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AbstractThe report presents the results of systematic first-principle FLAPW–GGA calculations of a series of metallic tetraborides MB_4 (where M = Ru, Rh, Pd, Os, Ir, and Pt) with space groups Pmmn , Immm , R -3 m , and Pnnm . Their equilibrium structural parameters, cohesion and formation energies, elastic constants, anisotropies, Vickers microhardnesses, Debye temperatures, sound velocities, as well as electronic properties and interatomic interactions are estimated and analyzed as compared to each other and the available theoretical data.
40

Smith, John R., e Amitava Banerjea. "New Approach to Calculation of Total Energies of Solids with Defects: Surface-Energy Anisotropies". Physical Review Letters 59, n. 21 (23 novembre 1987): 2451–54. http://dx.doi.org/10.1103/physrevlett.59.2451.

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41

Bao, Weizhu, Wei Jiang, Yan Wang e Quan Zhao. "A parametric finite element method for solid-state dewetting problems with anisotropic surface energies". Journal of Computational Physics 330 (febbraio 2017): 380–400. http://dx.doi.org/10.1016/j.jcp.2016.11.015.

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42

De Philippis, Guido, Antonio De Rosa e Francesco Ghiraldin. "Rectifiability of Varifolds with Locally Bounded First Variation with Respect to Anisotropic Surface Energies". Communications on Pure and Applied Mathematics 71, n. 6 (28 agosto 2017): 1123–48. http://dx.doi.org/10.1002/cpa.21713.

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43

Doi, Tomotaka, e Takatoki Yamamoto. "Optical Etching to Pattern Microstructures on Plastics by Vacuum Ultraviolet Light". Materials 13, n. 9 (11 maggio 2020): 2206. http://dx.doi.org/10.3390/ma13092206.

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We proposed and demonstrated an optical dry etching method for transferring a pattern on a photomask to a surface of plastics by decomposing the irradiated area using the high energy of vacuum ultraviolet light (VUV) at room temperature and pressure. Two kinds of wavelengths of 160 nm and 172 nm were used as the vacuum ultraviolet light, and the patterning performances for polymethyl methacrylate (PMMA) and polycarbonate (PC) were compared. As a result, it was revealed that proportional relationships were obtained between the etching rate and the irradiation dose for both wavelengths, and the cross-sectional profiles were anisotropic. In addition, both PMMA and PC were etched at a wavelength of 160 nm, whereas PC could not be etched at a wavelength of 172 nm, suggesting that it correlates with the bond dissociation energies of the molecular bonds of the materials and the energies of the photons. Furthermore, by combining this method with the optical bonding method that we had previously developed to bond surfaces irradiated with VUV, we have demonstrated a method for fabricating microfluidic devices by irradiating only with VUV. This paper shows that this technique is a new microfabrication method suitable for simple and mass production of plastic materials.
44

GARCKE, HARALD, BRITTA NESTLER, BJÖRN STINNER e FRANK WENDLER. "ALLEN–CAHN SYSTEMS WITH VOLUME CONSTRAINTS". Mathematical Models and Methods in Applied Sciences 18, n. 08 (agosto 2008): 1347–81. http://dx.doi.org/10.1142/s0218202508003066.

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We consider the evolution of a multi-phase system where the motion of the interfaces is driven by anisotropic curvature and some of the phases are subject to volume constraints. The dynamics of the phase boundaries is modeled by a system of Allen–Cahn type equations for phase field variables resulting from a gradient flow of an appropriate Ginzburg–Landau type energy. Several ideas are presented in order to guarantee the additional volume constraints. Numerical algorithms based on explicit finite difference methods are developed, and simulations are performed in order to study local minima of the system energy. Wulff shapes can be recovered, i.e. energy minimizing forms for anisotropic surface energies enclosing a given volume. Further applications range from foam structures or bubble clusters to tessellation problems in two and three space dimensions.
45

Petrera, Sergio. "Recent results from the Pierre Auger Observatory". EPJ Web of Conferences 208 (2019): 08001. http://dx.doi.org/10.1051/epjconf/201920808001.

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In this paper some recent results from the Pierre Auger Collaboration are presented. These are the measurement of the energy spectrum of cosmic rays over a wide range of energies (1017.5 to above 1020 eV), studies of the cosmic-ray mass composition with the fluorescence and surface detector of the Observatory, the observation of a large-scale anisotropy in the arrival direction of cosmic rays above 8 × 1018 eV and indications of anisotropy at intermediate angular scales above 4 × 1019 eV. The astrophysical implications of the spectrum and composition results are also discussed. Finally the progress of the upgrade of the Observatory, AugerPrime is presented.
46

Li, Xiang, Xiaojuan Zhu, Dong Pan, Yan Xue, Qingqing Jia, Fang Liu e Zhenghua Li. "Magnetic domains characterization of crystalline Fe3O4 under DC and AC magnetic field". Microscopy 68, n. 4 (29 aprile 2019): 310–15. http://dx.doi.org/10.1093/jmicro/dfz018.

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Abstract Fe3O4 nanoparticles with crystallite sizes around 10 nm were synthesized by an emulsion method. X-ray diffractometer (XRD) shows that nanocrystalline Fe3O4 possesses face center cubic structure. The magnetic characteristics are investigated by magnetic force microscopy (MFM). Magnetic field directions were applied parallel and perpendicular to the Fe3O4 sample surface for magnetic measurements. Under the perpendicular magnetic field, the phase images of most magnetic nanoparticles exhibit bright or dark MFM contrast. In comparison, the parallel field phase images display a bright–dark dipole MFM contrast, with in-plane magnetic domain configurations. Furthermore, the investigation of strip domains inside Fe3O4 particles under altering magnetic fields indicates the existence of magnetic anisotropy energies, dipole energies as well as inter-grain coupling energies inside the clusters. This approach for probing magnetic responses on nanoscale magnetic domains can be further extended to the analysis of local physical features.
47

Mu, Yan, Andrew Houk e Xueyu Song. "Anisotropic Interfacial Free Energies of the Hard-Sphere Crystal−Melt Interfaces†". Journal of Physical Chemistry B 109, n. 14 (aprile 2005): 6500–6504. http://dx.doi.org/10.1021/jp046289e.

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48

Iglesias, José A. "Symmetry and scaling limits for matching of implicit surfaces based on thin shell energies". ESAIM: Mathematical Modelling and Numerical Analysis 55, n. 3 (maggio 2021): 1133–61. http://dx.doi.org/10.1051/m2an/2021018.

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In a recent paper by Iglesias et al. [Found. Comput. Math. 18 (2018) 891–927] a variational model for deformations matching a pair of shapes given as level set functions was proposed. Its main feature is the presence of anisotropic energies active only in a narrow band around the hypersurfaces that resemble the behavior of elastic shells. In this work we consider some extensions and further analysis of that model. First, we present a symmetric energy functional such that given two particular shapes, it assigns the same energy to any given deformation as to its inverse when the roles of the shapes are interchanged, and introduce the adequate parameter scaling to recover a surface problem when the width of the narrow band vanishes. Then, we obtain existence of minimizing deformations for the symmetric energy in classes of bi-Sobolev homeomorphisms for small enough widths, and prove a Γ-convergence result for the corresponding non-symmetric energies as the width tends to zero. Finally, numerical results on realistic shape matching applications demonstrating the effect of the symmetric energy are presented.
49

Amelchakov, M. B., A. G. Bogdanov, A. Chiavassa, A. N. Dmitrieva, K. G. Kompaniets, S. S. Khokhlov, R. P. Kokoulin et al. "Cosmic-Ray Anisotropy Study by Means of Detection of Muon Bundles". Astrophysical Journal 945, n. 2 (1 marzo 2023): 123. http://dx.doi.org/10.3847/1538-4357/acb1fc.

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Abstract In this work, we use muon bundles, which are formed in extensive air showers and detected at the ground level, as a tool for searching for anisotropy in high-energy cosmic rays. Such choice is explained by the penetrating ability of muons that allows them to retain the direction of primary particles with good accuracy. In 2012–2022, we performed long-term muon-bundle detection with the coordinate-tracking detector DECOR, which is a part of the Experimental Complex NEVOD (MEPhI, Moscow). To search for cosmic-ray anisotropy, muon bundles arriving at zenith angles in the range from 15° to 75° in the local coordinate system are used. During the entire period of data taking, about 14 million of such events have been accumulated. In this paper, we describe some methods developed in the Experimental Complex NEVOD and implemented in our research, including: the method for compensating for the influence of meteorological conditions on the intensity of muon bundles at the Earth’s surface, the method for accounting for the design features of the detector and the inhomogeneity of the detection efficiency for different directions, as well as the method for estimating the primary energies of cosmic rays. Here we present the results of the search for the dipole anisotropy of cosmic rays with energies in the PeV region and also compare them with the results obtained at other scientific facilities.
50

Deij, M. A., J. H. Los, H. Meekes e E. Vlieg. "On the determination of step energies. Theoretical considerations and application to an anisotropic Kossel model". Journal of Applied Crystallography 39, n. 4 (15 luglio 2006): 563–70. http://dx.doi.org/10.1107/s0021889806017857.

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Steps on surfaces are important in crystal growth theory, as the step free energy determines the two-dimensional nucleation rate, island growth, step flow and spiral growth. In this paper, it is illustrated that in general in lattice models the step energy of a single step cannot be determined directly by counting broken bonds. A new method is proposed that uses the geometry of a step together with the bonding topology, allowing for a straightforward determination of single-step energies for any case. The method is applied to an anisotropic Kossel model.

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