| 1. |
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| 2. |
- Anderson, D., et al.
(författare)
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Modulational instabilities within the thermal wave model description of high energy charged particle beam dynamics
- 1999
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 258:4-6, s. 244-248
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Tidskriftsartikel (refereegranskat)abstract
- Within the thermal wave model (TWM) description, an investigation was made of the longitudinal instability properties of a coasting high energy charged particle beam, where the interaction between the beam and its surroundings is characterized in terms of a complex impedance. The analysis is shown to correctly reproduce the characteristic features of the coherent instability as obtained previously by conventional techniques based on the Vlasov equation for the beam distribution. The results further validate the TWM approach as a consistent alternative description for analyzing the dynamics of high energy charged particle beams.
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| 3. |
- Andersson, Ove, et al.
(författare)
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Reorientational relaxation in C60 following a pressure induced change in the pentagon/hexagon equilibrium ratio
- 1995
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Ingår i: Physics Letters A. - : Elsevier Science B.V.. - 0375-9601 .- 1873-2429. ; 206:3-4, s. 260-264
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Tidskriftsartikel (refereegranskat)abstract
- The orientational structure of C60 depends on pressure and temperature. Pressurization below the glass transition temperature Tg can freeze in non-equilibrium orientational structures. The relaxation of such structures on heating through Tg has been studied through thermal conductivity measurements and the effects observed are explained in a simple model.
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| 4. |
- Basylko, S. A., et al.
(författare)
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Coulomb glass in the restricted random phase approximation
- 2002
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 298:06-maj, s. 416-421
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Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional model of N/2 electrons localized on N randomly distributed donor sites of density n and with the acceptor charge uniformly smeared on these sites, -e/2 on each. has been considered in the restricted random phase approximation (RRPA) which uses the set of 3N Fourier components of the local charge density as the independent collective variables. The energy e(T) per site and the density of one-site excitation energy (DOSE) g(epsilon) are shown to he, respectively, in excellent quantitative and in good qualitative agreement with the Monte Carlo simulation data in the whole temperature region 0.1 < T < 100, where these simulations were performed (e(2)n(1/3)/k(B) being the temperature scale). The pair correlator for the one-site energies g(epsilon,+/-epsilon, r) is found to have the slow decoupling law similar to(+/-1/r) for T less than or similar to 1 and r much greater than r(d) (r(d), Debye screening radius). The status of the commonly accepted asymptotic g(epsilon) similar to (epsilon - mu)(d-1) (d and mu being, respectively, the spatial dimension and the Fermi energy) is discussed. The deduction of this asymptotic is shown to be based on the strong and questionable conjecture about decoupling of correlations between one-site excitation energies in the vicinity of mu.
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| 5. |
- Basylko, S. A., et al.
(författare)
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Ground-state study of a donor-acceptor model with finite charge-transfer energy
- 2000
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 271:02-jan, s. 134-138
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Tidskriftsartikel (refereegranskat)abstract
- A donor-acceptor model with randomly distributed N donor and N acceptor sites and with finite charge transfer energy Delta is investigated at zero temperature by means of computer simulations on two-dimensional samples of different sizes, We demonstrate that the density of one-electron excitations g(epsilon) for accepters in the vicinity of the Fermi energy mu depends essentially on the size of the sample investigated and that g(epsilon) further away from mu exhibits a size-independent power-law with the non-universal exponent decreasing with increasing Delta. Rigorous relations for mu and for the mapping of g(epsilon) for donors into g(epsilon) for accepters are also given.
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| 6. |
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| 7. |
- Bonnaud, Etienne L., et al.
(författare)
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Inertia and damping effects on the damage-dependent burst size distribution of fiber bundles
- 2001
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 290, s. 261-269
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Tidskriftsartikel (refereegranskat)abstract
- Distributions of simultaneous fiber failures—bursts—in loaded fiber bundles are studied considering inertia and damping. Resulting burst size distributions have universal properties: all approach the power law DΔΔ−2.5 for larger burst sizes Δ. Momentary burst size distributions evolve with increasing damage and do not follow power laws but are still universal. Finally, it is briefly outlined how to use distribution progression to assess damage state.
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| 8. |
- Brown, Harvey R., et al.
(författare)
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Remarks on identical particles in de Broglie-Bohm theory
- 1999
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 251:4, s. 229-235
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Tidskriftsartikel (refereegranskat)abstract
- It is argued that the topological approach to the (anti-) symmetrisation condition for the quantum state of a collection of identical particles, defined in the "reduced" configuration space, is particularly natural from the perspective of de Broglie-Bohm pilot-wave theory.
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| 9. |
- Dimitrevski, K., et al.
(författare)
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Analysis of stable self-trapping of laser beams in cubic-quintic nonlinear media
- 1998
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Ingår i: Physics Letters A. - : Elsevier. - 0375-9601 .- 1873-2429. ; 248:5-6, s. 369-376
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Tidskriftsartikel (refereegranskat)abstract
- A numerical and analytical analysis of two-dimensional laser beam propagation in cubic-quintic nonlinear optical media demonstrates the existence of stable stationary radially symmetric modes. By means of a variational method, involving super-Gaussian trial functions and Ritz optimization, approximate stationary solutions are obtained, showing very good agreement with numerical results, even in the strongly non-linear, almost saturated, regime. The stability of the stationary modes are verified by analytical analysis and by direct numerical simulations.
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| 10. |
- Dyakonov, V., et al.
(författare)
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Spin-wave resonance in the La0.7Mn1.3O3-delta film
- 2000
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Ingår i: Physics Letters A. - 0375-9601 .- 1873-2429. ; 268:3, s. 202-207
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Tidskriftsartikel (refereegranskat)abstract
- The spin-wave resonance (SWR) spectra have been observed in the (001) oriented La0.7Mn1.3O3-delta epitaxial films. The spectra consist of a series of well-resolved spin-wave modes clearly seen in the: perpendicular external field configuration. It is shown that the spins are completely pinned on both sides of the film surface. Based on a study of the SWR spectra the value of the spin-wave exchange constant, D, is found to be 150 meV Angstrom(2). This value of. D correlates well with this one determined for all known until now manganites.
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