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91.
Crystallography Reports - The specific features of the transport of thermal-frequency phonons at liquid-helium (He) temperatures under the conditions of non-stationary measurements and thermal... 相似文献
92.
93.
We study the extended Korteweg-de Vries equation, that is, the usual Korteweg-de Vries equation but with the inclusion of an extra cubic nonlinear term, for the case when the coefficient of the cubic nonlinear term has an opposite polarity to that of the coefficient of the linear dispersive term. As this equation is integrable, the number and type of solitons formed can be determined from an appropriate spectral problem. For initial disturbances of small amplitude, the number and type of solitons generated is similar to the well-known situation for the Korteweg-de Vries equation. However, our interest here is in initial disturbances of larger amplitude, for which there is the possibility of the generation of large-amplitude "table-top" solitons as well as small-amplitude solitons similar to the solitons of the Korteweg-de Vries equation. For this case, and in contrast to some earlier results which assumed that an initial disturbance in the shape of a rectangular box would be typical, we show that the number and type of solitons formed depend crucially on the disturbance shape, and change drastically when the initial disturbance is changed from a rectangular box to a "sech"-profile. (c) 2002 American Institute of Physics. 相似文献
94.
G.A. Mourou N.J. Fisch V.M. Malkin Z. Toroker E.A. Khazanov A.M. Sergeev T. Tajima B. Le Garrec 《Optics Communications》2012,285(5):720-724
A new amplification method, weaving the three basic compression techniques, Chirped Pulse Amplification (CPA), Optical Parametric Chirped Pulse Amplification (OPCPA) and Plasma Compression by Backward Raman Amplification (BRA) in plasma, is proposed. It is called C3 for Cascaded Conversion Compression. It has the capability to compress with good efficiency kilojoule to megajoule, nanosecond laser pulses into femtosecond pulses, to produce exawatt-and-beyond peak power. In the future, C3 could be used at large-scale facilities such as the National Ignition Facility (NIF) or the Laser Megajoule (LMJ) and open the way to zettawatt level pulses. The beam will be focused to a wavelength spot size with a f#1. The very small beam size, i.e. few centimeters, along with the low laser repetition rate laser system will make possible the use of inexpensive, precision, disposable optics. The resulting intensity will approach the Schwinger value, thus opening up new possibilities in fundamental physics. 相似文献
95.
E. V. Charnaya C. Tien T. Y. Her S. N. Ivanov E. N. Khazanov 《Physics of the Solid State》2003,45(9):1672-1675
The spin-lattice relaxation time of 27Al nuclei residing in the octahedral and tetrahedral oxygen environment in Y3 ?xLuxAl5O12 mixed aluminum-yttrium garnets was measured by the NMR method for 0≤x≤3. A maximum in the concentration dependence of the relaxation time was observed for both crystallographic positions at x=0.75; this maximum correlates with the minimum in the NMR linewidth, indicating the ordering obtained as the yttrium and lutetium ions occupy the dodecahedral positions in the garnet lattice. 相似文献
96.
Methods for computing scalar and vector spectral characteristics of a polynomial matrix are proposed. These methods are based on determining the so-called generating vectors (eigenvectors and principal vectors) by using the method of rank factorization of polynomial matrices. The possibility of extending the methods to the case of two-parameter polynomial matrices is indicated. Bibliography: 4 titles. 相似文献
97.
V. B. Khazanov 《Journal of Mathematical Sciences》2004,121(4):2538-2545
Spaces of multiparameter rational vectors, i.e., of vectors whose components are rational functions in several variables, and polynomial bases of their subspaces are considered. The conjecture that any subspace in the space of multiparameter rational vectors possesses a free polynomial basis, i.e., a basis such that the associated basis multiparameter polynomial matrix has no finite regular spectrum, is disproved by an example. Some consequences of this fact are indicated. Simpler proofs of some properties of the singular spectra of basis polynomial matrices corresponding to the null-spaces of a singular polynomial matrix are presented. Bibliography: 5 titles. 相似文献
98.
Efim Pelinovsky Andrey V. Razin Elena V. Sasorova 《Waves in Random and Complex Media》1998,8(2):255-268
The problem of the propagation of small-amplitude surface gravity waves in a basin of constant mean depth with one- and two-dimensional bottom roughness is solved in the framework of the Berkhoff model by a mean-field method. In both cases the solutions obtained are compared with the solutions of sets of exact linearized equations of the hydrodynamics of an incompressible fluid. The comparison of the exact and approximate mean-field attenuation coefficients has shown that the Berkhoff approximation is appropriate for the solution of this problem in the case of shallow water for an arbitrary correlation length of bottom irregularities and in the case of arbitrary depth and large-scale irregularities. An explanation is given for the limits of applicability of the Berkhoff approximation which are connected with the weak variability of the vertical structure of the wave field in shallow water and in a basin with large-scale depth fluctuations. The mean-field attenuation coefficients reach their maximum values in the region koho≥1 (where ko is the wavenumber of the surface gravity wave in a basin of constant depth ho). The location of these maxima is practically independent of the correlation length of the bottom irregularities. For the case of one-dimensional irregularities the effect of bottom roughness on the surface gravity wave velocity is investigated. It is shown that the surface wave in a basin with an uneven bottom may propagate more slowly, as well as faster than the wave in a basin with an even bottom, depending on the relations between the wavelength, depth and correlation length of the bottom imperfections. 相似文献
99.
V. B. Khazanov 《Journal of Mathematical Sciences》1987,36(2):251-261
The investigation of spectral properties and characteristics of -matrices of general form is continued. The concept of a matrix solution is extended to the case of singular -matrices. The concept of reducing subspaces and the concepts of a block eigenvalue and a block eigenvector are generalized. Existence theorems are proved; spectral properties of matrix quantities associated with the concepts indicated and their generalizations are established.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 139, pp. 111–124, 1984. 相似文献
100.
Properties of the method of ΔW-q factorization of multiparameter polynomial matrices are analyzed. Modifications of the method,
used in solving spectral and other multiparameter problems of algebra, are discussed. Bibliogrhaphy: 11 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 309, 2004, pp. 154–165. 相似文献