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891.
We start with a stochastic flow of diffeomorphisms of the space. Particles enter the space at random times and places. Each particle is carried by the flow for some random amount of time. We examine the point process formed by the particles at a fixed time, on the evolution of that point process as time varies, and on the equilibrium law of the point process. 相似文献
892.
The last decade has seen increasing interest in techniques for the enhancement of digital speech signals. Significant gains have been made in terms of signal-to-noise ratio (SNR) and quality, but few techniques have produced improvements in intelligibility. A method for speech enhancement based on nonlinear expansion of the spectral envelope is presented. The expansion is consistent with both the long-term spectrum of the speech and with the probability that speech is present in a given sample. Objective SNR measures are used to compare this algorithm with the well-known spectral subtraction method, with an alternative expansion scheme, and with limiting SNRs resulting from perfect recovery of the amplitude spectrum. For the purpose of intelligibility assessments, a simplified version of the algorithm has been implemented on a Texas Instruments TMS320-C25 system. Listening trials with this real-time system, conducted using a modified rhyme test, have produced small, but consistent, improvements in articulation scores. 相似文献
893.
H. Ohmori S. Tomiyoshi H. Yamauchi H. Yamamoto 《Journal of magnetism and magnetic materials》1987,70(1-3):249-251
The compound Mn3Sn shows an interesting magnetic behavior. A triangular screw spin structure has been observed below 250 K, whose period is independent of temperature. The screw structure is sensitive to heat treatment, alloy composition and impurity content. 相似文献
894.
A. A. Chistyakov I. L. Martynov K. E. Mochalov V. A. Oleinikov S. V. Sizova E. A. Ustinovich K. V. Zakharchenko 《Laser Physics》2006,16(12):1625-1632
The optical properties of CdSe/ZnS semiconductor nanocrystals with the core-shell structure are studied upon visible-laser excitation in a wide range of flux densities. It is demonstrated that the dimensional quantization effect is preserved in the films with a limiting high concentration of nanocrystals. A strong bathochromic shift of the absorption and luminescence peaks relative to the peak positions in the corresponding spectra of nanocrystals in films with a relatively low concentration of nanocrystals and solutions is caused by a high concentration of nanocrystals and the dipole moment related to the asymmetry of the nanoparticles. The shift is varied from 35 to 50 nm depending on the film thickness. The luminescence spectra of the films remain unchanged upon an increase in the laser intensity to 1 × 106 W/cm2. The laser action on the nanoparticle films is studied at intensities (5 × 106?1 × 109 W/cm2) higher than the damage threshold. 相似文献
895.
Approximate Conditions and Passage to the Limit in Sobolev Spaces over Thin and Composite Structures
S. E. Pastukhova 《Journal of Mathematical Sciences》2006,133(1):931-948
Approximate properties of variable measures compose a base of the two-scale convergence method with respect to a variable
measure, which is used in averaging on periodic thin and composite structures. The paper gives a survey of methods for verifying
approximate properties. The main focus is on studying composite measures, which have been little studied.
__________
Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 16, Partial
Differential Equations, 2004. 相似文献
896.
A. Borgschulte R. Gremaud S. de Man R.J. Westerwaal J.H. Rector B. Dam R. Griessen 《Applied Surface Science》2006,253(3):1417-1423
The optical properties, the switching kinetics and the lifetime of hydrogen switchable mirrors based on Mg-Ni alloys are determined with particular regard to the composition of the optically active metal-hydride layer in combination with the thickness of the catalytic capping layer. For this, a high-throughput experiment is introduced. The switching kinetics and the reversibility of switchable mirrors are strongly thickness dependent, though the details hinge on the fine structure of the clustered capping layer. Therefore, the kinetics is correlated with the surface structures of Pd on MgyNi1−y as investigated by scanning tunneling microscopy. The results are explained by the so-called strong metal-support interaction (SMSI) state, characterized by a complete encapsulation of the capping layer clusters by oxidized species originating from the support. The SMSI-effect is less important with increasing Pd-layer thickness, and is suppressed by a good wetting of the Pd-clusters on the optically active film. This explains the critical thickness for the catalyzed hydrogen uptake observed in many switchable mirror systems. Moreover, the degradation of the kinetics during cycling is found to depend on the Pd-layer thickness and on the gas environment. Only films, covered with at least 15 nm Pd, show small degradation caused by the SMSI-effect. The SMSI-effect is partly reversible: after changing the gas environment from hydrogen to oxygen, the oxide on the Pd-clusters can be partly removed. 相似文献
897.
The influence of additives such as TiO2, Al2O3 and their mechanical mixture as well as aluminium oxide, the surface of which contains phosphorous and titanium-oxide nanostructures, on the combustibility of foam plast (trade mark PEN-I), produced on the basis of epoxide novolak block-copolymers, was studied. It was stated that the incorporation both phosphorous-containing and titanium-containing oxides in the composition results in significant (in two to five times) decreasing of the samples’ combustibility. The probable mechanism of inhibition of burning process for those combustion retarders was discussed. 相似文献
898.
899.
900.