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141.
A novel theoretical approach is applied to predict the propagation and transformation of transient nonlinear waves on a current. The problem was solved by applying an eigenfunction expansion method and the derived semi-analytical solution was employed to study the transformation of wave profile and the evolution of wave spectrum arising from the nonlinear interactions of wave components in a wave train which may lead to the formation of very large waves. The results show that the propagation of wave trains is significantly affected by a current. A relatively small current may substantially affect wave train components and the wave train shape. This is observed for both opposing and following current. The results demonstrate that the application of the nonlinear model has a substantial effect on the shape of a wave spectrum. A train of originally linear and very narrow-banded waves changes its one-peak spectrum to a multi-peak one in a fairly short distance from an initial position. The discrepancies between the wave trains predicted by applying the linear and nonlinear models increase with the increasing wavelength and become significant in shallow water even for waves with low steepness. Laboratory experiments were conducted in a wave flume to verify theoretical results. The free-surface elevations recorded by a system of wave gauges are compared with the results provided by the nonlinear model. Additional verification was achieved by applying a Fourier analysis and comparing wave amplitude spectra obtained from theoretical results with experimental data. A reasonable agreement between theoretical results and experimental data is observed for both amplitudes and phases. The model predicts fairly well multi-peak spectra, including wave spectra with significant nonlinear wave components. 相似文献
142.
Maria Aldona Augustyniak-Jabłokow Yurii V. Yablokov Bartłomiej Andrzejewski Wojciech Kempiński Szymon Łoś Krzysztof Tadyszak Mikhail Y. Yablokov Valentin A. Zhikharev 《Physics and Chemistry of Minerals》2010,37(4):237-247
The X-band EPR and magnetic susceptibility in the temperature range 4.2–300 K study of the shungite-I, natural nanostructured
material from the deposit of Shunga are reported. Obtained results allow us to assign the EPR signal to conduction electrons,
estimate their number, N
P, and evaluate the Pauli paramagnetism contribution to shungite susceptibility. A small occupation (~5%) of the localized
nonbonding π states in the zigzag edges of the open-ended graphene-like layers and/or on σ (sp
2+x
) orbitals in the curved parts of the shungite globules has been also revealed. The observed temperature dependence of the
EPR linewidth can be explained by the earlier considered interaction of conduction π electrons with local phonon modes associated
with the vibration of peripheral carbon atoms of the open zigzag-type edges and with peripheral carbon atoms cross-linking
different nanostructures. The relaxation time T
2 and diffusion time T
D are found to have comparable values (2.84 × 10−8 and 1.73 × 10−8 s at 5.2 K, respectively), and similar dependence on temperature. The magnetic measurements have revealed the suppression
of orbital diamagnetism due to small amount of large enough fragments of the graphene layers. 相似文献