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61.
V. Ya. Shur G. G. Lomakin E. L. Rumyantsev O. V. Yakutova D. V. Pelegov A. Sternberg M. Kosec 《Physics of the Solid State》2005,47(7):1340-1345
The polarization switching is experimentally investigated in hot-pressed PLZT-x/65/35 ceramics with a lanthanum content from 5 to 12 at. %. The specific features in the temperature dependence of the polarization switching in a heterophase state are interpreted by analyzing the change in the switched charge measured over wide ranges of fields and temperatures. Particular emphasis is placed on the role of depolarization fields induced by interphase boundaries. A model of the evolution of polydomain nanostructures with a change in the temperature and in the response to an external field is considered. It is assumed that the low-temperature dielectric anomaly and the temperature hysteresis are associated with the loss of stability of a large-scale domain structure and its transformation into a nanodomain state. 相似文献
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The author presents a revised and detailed version of his theorem on the existence of Feller's extensions of Markov chains; to this end the broader notion of quasi-Feller extension is used. The existence of Markov chains dual to the chains with Borel space of states is derived from this result. Chains irreducible in the Orey sense are studied in most detail. For example, we prove that for such chains the quasi-Feller extension can be chosen recurrent or Liouville if the original chains possess these properties. 相似文献
65.
The Large-Eddy Simulation (LES) numerical system established since 2002 for jet-noise computation is first evaluated in terms of recent gains in accuracy with increased computer resources, and is then used to explore the relatively new “microjet” noise-reduction concept (injection of high-pressure microjets in the vicinity of the main jet nozzle exit), which currently attracts attention in the aeroacoustic community. The simulations, which are carried out with an emulation of the microjets by specially designed distributed sources of mass, momentum, and energy in the governing equations, are found to capture the essential features of the flow/turbulence and the far-field noise alteration by the microjets observed in experiments, and to reveal the subtle flow features responsible for the effect of injection on noise. They also confirm the experimental observation that in static conditions microjets provide a noise reduction comparable with that from chevrons in the low-frequency range, and probably have a less pronounced high-frequency penalty. This positive evaluation of the microjets concept is, however, mitigated by the far less favorable results of simulations in flight conditions, which were never studied experimentally. The latter results, which are awaiting an experimental verification, make a practical use of the concept in its current form rather unlikely. 相似文献
66.
We study the sensitivity of the steady-state electron transport that occurs within bulk wurtzite zinc oxide to variations in the non-parabolicity coefficient. An ensemble semi-classical three-valley Monte Carlo simulation approach is used for the purposes of this analysis. We find that for non-parabolicity coefficient selections beyond 0.4 eV −1, very few transitions to the upper energy conduction band valleys occur. This sensitivity to variations in the non-parabolicity coefficient has implications in terms of the form of the resultant velocity-field characteristics. 相似文献
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A. V. Talyzin U. Jansson A. V. Usatov V. V. Burlakov V. B. Shur Y. N. Novikov 《Physics of the Solid State》2002,44(3):506-508
Raman spectra from the first Ti fullerene complex Cp
2Ti(η2-C60) · C6H5CH3 are presented. Compared to spectra of pure C60, the spectra of the Ti complex exhibit a number of new peaks due to the symmetry lowering for C60. The A
g(2) mode is downshifted by 12 cm−1 compared to C60, which corresponds to a charge transfer of one electron per Ti-C60 bond. This value (6 cm−1 for one transferred electron) is identical to the downshift of the A
g(2) mode in alkali metal fullerides with ionic bonding. The spectra of Cp
2Ti(η2-C60) · C6H5CH3 were compared to the spectra of evaporated TixC60 films. The A
g(2) mode in Ti4C60 showed a downshift of about 25 cm−1 compared to pure C60, which corresponds to a charge transfer of one electron per Ti atom; this is similar to the ionic alkali metal fullerides
and different from η2-C60-type bonding.
From Fizika Tverdogo Tela, Vol. 44, No. 3, 2002, pp. 483–485.
Original English Text Copyright ? 2002 by Talyzin, Jansson, Usatov, Burlakov, Shur, Novikov.
This article was submitted by the authors in English. 相似文献
69.
M. G. Shur 《Mathematical Notes》1996,60(1):89-93
The theorem on the asymptotic equidistribution of the convolution powers of a symmetric probability measure given on a unimodular
group [1] deals with a measure whose convolution powers, starting from one of them, load an arbitrary prescribed nonempty
subset of the group. In the present note, we indicate the modifications that arise under the replacement of the above condition
by the requirement that the smallest closed subgroup (of the group considered) generated by the support of this measure coincide
with the group itself.
Translated fromMatematicheskie Zametki, Vol. 60, No. 1, pp. 120–126, July, 1996.
This research was partially supported by the International Science Foundation under grant No. 3J000. 相似文献
70.