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- Beličev, P.P., et al.
(författare)
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On localized modes in nonlinear binary kagome ribbons
- 2015
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- One of the attractive two-dimensional [2D] lattice configurations is characterized by kagome geometry. The specific arrangement of its elements, i.e. waveguides, in the form of periodic hexagons renders completely flat the first energy band in linear case. As a consequence, the localized ring-like eigenmodes belonging to the lowest energy state propagate without diffraction through the system [1, 2]. Here we study kagome ribbon [3], which can be interpreted as one-dimensional counterpart of the standard 2D kagome lattice, and can be fabricated by dint of the direct femtosecond laser inscription [4, 5].The existence, stability and dynamical properties of various localized modes in binary kagome ribbon with defocusing Kerr type of nonlinearity have been explored, both numerically and analytically. We derived the corresponding dispersion relation and the bandgap spectrum, confirmed the opening of mini-gaps in it and found several types of stable ring-like modes to exist: staggered, unstaggered and vortex. Beside these nonlinear mode configurations occurring in a semi-infinite gap, we investigated features of "hourglass" solutions, identified in [3] as interesting structures when kagome lattice dimensionality is reduced to 1D. In nonlinear binary kagome ribbon dynamically stable propagation of unstaggered rings, vortex modes with certain topological charge and hourglass solutions are observed, while the staggered ring solutions are destabilized. In addition, we examined possibility to generate stable propagating solitary modes inside the first mini-gap and found that these mode patterns localize within sites mutually coupled by smaller coupling constant. The last feature is opposite to the nonlinear localized solutions found in the semi-infinite gap.REFERENCES[1] R. A. Vicencio, C. Mejía-Cortés, J. Opt. 16, 015706 (2014).[2] R. A. Vicencio, M. Johansson, Phys. Rev. A 87, R061803 (2013).[3] M. Molina, Phys. Lett. A 376, 3458 (2012).[4] K. Davies et al., Opt. Lett. 21, 1729 (1996).[5] K. Itoh et al., MRS Bulletin 31, 620 (2006).
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| 2. |
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| 3. |
- Johansson, Magnus, et al.
(författare)
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Comment on "localized vortices with a semi-integer charge in nonlinear dynamical lattices"
- 2002
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 66:4, s. 048601-
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In a recent paper by Kevrekidis, Malomed, Bishop, and Frantzeskakis [Phys. Rev. E 65, 016605 (2001)] the existence of localized vortices with semi-integer topological charge as exact stationary solutions in a two-dimensional discrete nonlinear Schrödinger model is claimed, as well as the existence of an analog solution in the one-dimensional model. We point out that the existence of such exact stationary solutions would violate fundamental conservation laws, and therefore these claims are erroneous and appear as a consequence of inaccurate numerics. We illustrate the origin of these errors by performing similar numerical calculations using more accurate numerics.
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| 5. |
- Knutsson, Axel, et al.
(författare)
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Early stage spinodal decomposition and microstructure evolution in TiAlN : A combined in-situ SAXS and phase field study
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper describes in detail the microstructure and phase evolution in Ti0.33Al0.67N and Ti0.50Al0.50N coatings during isothermal annealing, studied by in-situ small angle x-ray scattering (SAXS), in combination with phase field simulations. We show that the isostructural spinodal decomposition occurs in two stages. During the initial stage, the phase segregation proceeds with a constant size of AlN- and TiN-rich domains with an experimentally measured radius of ~0.7 nm for 5 and 20 min at 900 and 850 °C respectively in the Ti0.50Al0.50N alloy. The length of the initial stage depends on temperature as well as metal composition, and is shorter for the higher Al-content coating. After the initial stage, the coherent cubic AlN- and TiN-rich domains coarsen. The coarsening process is kinetically limited by diffusion, which allowed us to estimate the diffusivity and activation energies of the metals to 1.4·10-7 m2s-1 and 3.14 eV at-1 respectively.
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| 8. |
- Risacher, C., et al.
(författare)
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A 279-381 GHz SIS Receiver for the APEX Telescope
- 2006
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Ingår i: Proceedings of the 16th International Symposium on Space Terahertz Technology, Chalmers University of Technology, Gothenburg, Sweden, May 2-4, 2005. ; , s. 432-437
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Sobolev, A.M., et al.
(författare)
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Methanol masers in star forming sites of the perseus spiral arm
- 2007
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Ingår i: Proceedings of "Millimeter wave astronomy and star formation", ed. I. Zinchenko, Nizhny Novgorod, Russia, August 2007, Inst. of Applied Physics RAS. ; , s. 61-67
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Yalamanchili, Kumar, et al.
(författare)
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Influence of microstructure and mechanical properties on the wear behavior of reactive arc deposited Zr-Si-N coatings
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Zr-Si-N coatings were grown over WC-Co substrates by an industrial reactive arc deposition technique. Si content of the coatings was varied between 0.2 and 6.3 at. % to cause a microstructural transition from a columnar to an equiaxed nanocomposite microstructure resulting in alterations of the mechanical properties such as hardness, elastic modulus, and fracture resistance. A reciprocating sliding wear test with a counter material of WC-Co shows a systematic change in wear rate as a function of Si content of the coatings. A maximum wear rate of 1.4x10-5 mm3/Nm is seen for the coating with 1.8 at. % Si (columnar microstructure), which then gradually decreases to 0.6x10-5 mm3/Nm at 6.3 at. % Si (nanocomposite structure). Electron microscopy observations of the wear track reveal tribooxidation as the dominating wear mode. The growth rate of the tribo-oxide layer is the wear rate determining mechanism. Higher growth rate of tribo-oxide layer in the columnar structured coating leads to layer delamination and high wear rate. While the lower growth rate of tribo-oxide layer in the nanocomposite coating results in reduced wear rate of the coatings. Nanocomposite coatings show superior resistance to both static and tribo-oxidation compared to the columnar structured coatings.
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