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961.
Effect of track stiffness on vibration levels in railway tunnels 总被引:1,自引:0,他引:1
The paper discusses the difficulties in comparing and drawing conclusions from vibration measurements made in different railway tunnels. A number of new measurements are presented, which have been made and analyzed on a consistent basis. The track stiffness has been determined for each of the measurements. Graphs are presented which indicate the level of rail and tunnel floor vibration likely to occur for different track stiffnesses. The variance in the measurement results also indicates the potential error in using the data to predict vibration levels in new situations. 相似文献
962.
Miroslav Ploščica 《Algebra Universalis》2003,49(1):1-12
963.
R. A. Sharipov 《Journal of Mathematical Sciences》2004,119(2):281-291
A construction of normal shift along trajectories of a Newtonian dynamical system in the case of an extremely singular initial hypersurface collapsing to a single point is considered. A new class of Newtonian dynamical systems is introduced: systems admitting normal blow-up of points. The class is described in terms of differential equations of normality. Bibliography: 20 titles. 相似文献
964.
We present a model that provides a plausible explanation of the effect of zero-resistance and zero-conductance states in two-dimensional electron systems subjected to a magnetic field and irradiated with microwaves observed in a number of experiments and of the effect’s main features. The model is based on the concept of absolute negative conductivity associated with photon-assisted scattering of electrons on impurities. It is shown that the main features of the effect can be attributed to the interplay of different electron scattering mechanisms. 相似文献
965.
S. K. Gorbatsevich I. A. Kaputskaya S. A. Maskevich S. Yu. Mikhnevich N. D. Strekal’ 《Optics and Spectroscopy》2004,97(2):238-243
The fluorescence of solid solutions of CdSe/ZnS quantum dots and the organic dye DODCI is investigated. It is shown that nonradiative transfer of electronic excitation energy to dye molecules, which with some probability lose their acceptor properties as a result of photoisomerization or photodegradation, is responsible for a significant increase in the fluorescence intensity of a donor. The degree of polarization of the donor fluorescence attains values exceeding 0.5, which is due to the difference in the fluorescence quantum yields of donors with different orientations of the oscillator with respect to the electric vector of an excitation light wave. A numerical simulation of the experimentally observed dependences is performed. 相似文献
966.
Transformations of chemical species formed by the reaction of gaseous BF3 with high pressure and silica preheated at 473 and 1093 K were studied with the use of infrared absorption spectrometry. The species containing -BF2 and the species containing >BF were transformed to each other on the highly-reacted silica depending on the pressure of BF3 in cell, and some of the species containing -BF2 were also desorbed without their transformations to the species containing >BF. H2O played important roles in these transformations. 相似文献
967.
968.
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970.
S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of the Ukraine. Translated from Prikladnaya Mekhanika, Vol. 31, No. 9, pp. 15–23, September, 1995. 相似文献