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941.
A waveguide with a rectangular cross section of size and orientation slowly changing along the length of the waveguide is considered. Methods of the canonical perturbation theory are used to describe the ray dynamics in the waveguide. As the size and orientation of the cross section slowly change along the ray trajectory, certain resonance conditions may be satisfied. The phenomena of scattering on resonance and capture into resonance is studied. These phenomena lead to destruction of the adiabatic invariance in the system. Bibliography: 12 titles.__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 300, 2003, pp. 173–179 相似文献
942.
Role of the microstructure on the transport properties of Y-doped zirconia and Gd-doped ceria 总被引:1,自引:1,他引:0
Transmission electron microscopy characterizations and XPS analyses have allowed us to show the influence of the microstructure
and nanochemistry on the transport properties of Y2O3-(9 mol%)-stabilized zirconia (YSZ) and Gd2O3 (10 mol%)-doped ceria (GDC). The grain boundary electrical conductivity (σgb) and oxygen diffusion coefficient (Do) of conventional YSZ ceramics increase with the grain size, while an opposite behavior was found for GDC samples. This difference
was attributed to glassy precipitates present at YSZ grain boundaries. Furthermore, it was shown that kinetic demixing processes
take place during cooling, at the end of sintering. This causes important changes in the cationic species distribution at
interfaces and plays an important role on the transport properties of these two materials.
Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15 – 21, 2002. 相似文献
943.
944.
Nicholas I. M. Gould Dominique Orban Annick Sartenaer Phillipe L. Toint 《4OR: A Quarterly Journal of Operations Research》2005,3(3):227-241
In this paper, we examine the sensitivity of trust-region algorithms on the parameters related to the step acceptance and
update of the trust region. We show, in the context of unconstrained programming, that the numerical efficiency of these algorithms
can easily be improved by choosing appropriate parameters. Recommended ranges of values for these parameters are exhibited
on the basis of extensive numerical tests.
MSC classification:
65K05, 90C26, 90C30 相似文献
945.
V. B. Kobychev N. M. Vitkovskaya I. L. Zaitseva B. A. Trofimov 《Journal of Structural Chemistry》2004,45(6):940-944
The profiles of reactions leading to pyrrole anion N-adducts with CO2 and CS2 have been studied by the ab initio (RHF/6-31+G*, MP2/6-31+G*) and density functional (B3LYP/6-31+G*) methods. Addition of the pyrrole anion to the carbon disulfide molecule is accompanied by the appearance of a minimum corresponding to a pre-reaction complex. The transformation of the complex to the N-pyrrolyldithiocarboxylate anion occurs via a low activation barrier, which is due to repolarization of the C=S bonds. The profile of the reaction leading to the pyrrole anion N-adduct with CO2 does not contain any intermediate stationary points throughout the whole route from reagents to products.Original Russian Text Copyright © 2004 by V. B. Kobychev, N. M. Vitkovskaya, I. L. Zaitseva, and B. A. Trofimov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 6, pp. 990–993, November–December, 2004. 相似文献
946.
Savos'kin M. V. Yaroshenko A. P. Shologon V. I. Galushko L. Ya. 《Russian Journal of Applied Chemistry》2003,76(7):1179-1181
Petroleum sorption on expanded graphite prepared from residual graphite hydrosulfate at 300-900°C was studied as influenced by pretreatment of the sorbent with water. 相似文献
947.
The appearance of a steady current in a helical quantum wire under circularly polarized light is predicted. The effect is associated with the appearance of a travelling electromagnetic wave in the coordinate system related to the wire, the wavelength being determined by the period of the helix. The gyrotropy of a medium consisting of parallel quantum wires is considered. 相似文献
948.
Annihilation of positrons in hydrogen-saturated titanium 总被引:1,自引:0,他引:1
K. P. Aref’ev O. V. Boev O. N. Imas A. M. Lider A. S. Surkov I. P. Chernov 《Physics of the Solid State》2003,45(1):1-5
The effect of atomic hydrogen on the electronic structure of α-titanium samples is studied using the electron-positron annihilation methods. It is shown that different states of hydrogen atoms are manifested in different ways in the positron lifetime distribution spectrum. The results of theoretical calculations of the first component of the positron lifetime are in accord with the obtained experimental data. 相似文献
949.
Kurenkov V. F. Zhelonkina T. A. Ryabysheva N. A. Lobanov F. I. 《Russian Journal of Applied Chemistry》2003,76(8):1310-1314
The influence of single- and double-charged cations on degradation of metal 2-acrylamido-2-methylpropanesulfonate-N-vinylpyrrolidine copolymers in aqueous solutions in the presence of potassium peroxodisulfate, K2S2O8, at 50 and 70°C was studied by viscosimetry. 相似文献
950.
I. R. Martin V. D. Rodriguez M. Morales U. R. Rodriguez-Mendoza V. Lavin 《Journal of Applied Spectroscopy》1995,62(5):865-871
This work has been partially supported by Gobierno Autonomo de Canarias under contact number 226–265/93. 相似文献