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981.
Resonance Raman scattering by exciton polaritons in crystals of CuGaS2 under excitation with the 4880 and 4765 Å lines of an Ar+ laser at 9 K is studied. Lines of one-and two-phonon scattering of excitonic polaritons are found and studied. It is shown that the 1LO and 2LO phonons are arranged in accordance with their energies as the Stokes shifts move farther away from the excitation energy. 相似文献
982.
The normal form of certain polynomial matrices is found.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova Akademii Nauk SSSR, Vol. 175, pp. 63–68, 1989. 相似文献
983.
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
984.
985.
M. Waris 《Applied Surface Science》2006,252(20):7327-7330
This work demonstrates anodic bonding of Zerodur glass having very low co-efficient of thermal expansion (CTE) to Si, Zerodur glass to thermally grown silicon dioxide on silicon and Pyrex glass to Ge. Bonding results, using point cathode contact and plate cathode contact configurations, are discussed. Bonding parameters, i.e. applied dc voltage, temperature and bonding time were determined. Heating and cooling rates for crack-free bonding of Zerodur glass were also determined. 相似文献
986.
M. Olivares-Marín C. Fernández-González V. Gómez-Serrano 《Applied Surface Science》2006,252(17):5980-5983
Using cherry stones, the preparation of activated carbon has been undertaken in the present study by chemical activation with potassium hydroxide. A series of KOH-activated products was prepared by varying the carbonisation temperature in the 400-900 °C range. Such products were characterised texturally by gas adsorption (N2, −196 °C), mercury porosimetry, and helium and mercury density measurements. FT-IR spectroscopy was also applied. The carbons prepared as a rule are microporous and macroporous solids. The degree of development of surface area and porosity increases with increasing carbonisation temperature. For the carbon heated at 900 °C the specific surface area (BET) is 1624 m2 g−1, the micropore volume is 0.67 cm3 g−1, the mesopore volume is 0.28 cm3 g−1, and the macropore volume is 1.84 cm3 g−1. 相似文献
987.
E. E. Shalygina V. V. Molokanov M. A. Komarova 《Journal of Experimental and Theoretical Physics》2002,95(3):511-516
Magnetooptical investigation of the micromagnetic structure of Co69Fe4Si12B15 amorphous microwires 10–50 μm in diameter is carried out. The existence of domains with transverse circumferential magnetization is experimentally demonstrated in the near-surface region of microwires. The dependence of the width of circular domains on the length and diameter of wires is obtained. It is shown that the near-surface micromagnetic structure of amorphous wires is changed under a stretch-induced stress. It is proved that the magnetization reversal of microwires in a longitudinal magnetic field occurs due to the rotation of local magnetization vectors in circular domains. 相似文献
988.
989.
990.
We study networks of coupled phase oscillators and show that
network architecture can force relations between average
frequencies of the oscillators. The main tool of our analysis is
the coupled cell theory developed by Stewart, Golubitsky, Pivato,
and Torok, which provides precise relations between network
architecture and the corresponding class of ODEs in RM and
gives conditions for the flow-invariance of certain polydiagonal
subspaces for all coupled systems with a given network
architecture. The theory generalizes the notion of fixed-point
subspaces for subgroups of network symmetries and directly extends
to networks of coupled phase oscillators. For systems of coupled phase oscillators (but not generally for ODEs in RM, where M ≥ 2), invariant polydiagonal subsets of
codimension one arise naturally and strongly restrict the network
dynamics. We say that two oscillators i and j coevolve if the polydiagonal θi = θj is flow-invariant, and show that the average frequencies of these
oscillators must be equal. Given a network architecture, it is shown that coupled cell theory
provides a direct way of testing how coevolving oscillators form
collections with closely related dynamics. We give a
generalization of these results to synchronous clusters of phase
oscillators using quotient networks, and discuss implications for
networks of spiking cells and those connected through buffers that
implement coupling dynamics. 相似文献