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991.
In search of a noncontact underwater acoustic source 总被引:7,自引:0,他引:7
S. V. Egerev 《Acoustical Physics》2003,49(1):51-61
The history of studies of the photoacoustic effect in liquids and its applications to the development of a “virtual” source of underwater acoustic signals is briefly reviewed. The problem of the efficiency of the photoacoustic conversion is considered. The modes of laser generation of sound, i.e., the thermooptical, nonlinear surface, and nonlinear bulk modes of operation, are discussed taking into account the real features of the marine environment, the most important of them being the surface waves. A review of the publications concerned with the problem of a moving photoacoustic source is presented. Advances in the photoacoustic underwater remote sensing technology are described. 相似文献
992.
The kinetics of oxygen exchange are of primary importance for the application of titanates as fast resistive oxygen sensors.
The sensor’s conductivity is correlated with the oxygen partial pressure pO2 of the surrounding atmosphere: Due to oxygen surface transfer and subsequent diffusion of oxygen vacancies V
O
··
, a pO2 change gives rise to a conductivity change of the sample. While bulk diffusion usually occurs very fast, the surface transfer
reaction becomes the rate determining step for thin samples and for low temperatures. We have shown that in the case of acceptor
doped SrTiO3 the kinetics of the surface transfer reaction can be strongly influenced through stoichiometric changes brought about by
thin coatings of alkaline earth metal oxides (e.g. SrO). In contrast to the commonly used jump method (conductivity response
to a sudden pO2 change in the time domain), a model is presented which is based on the frequency-domain analysis of amplitude and phase shift
of the response signal obtained from a pO2 modulation in a fast kinetic measurement set-up. This method allows not only for measuring response times in the sub-millisecond
range but also for distinguishing between behaviour either controlled by volume diffusion or by surface transfer reaction.
Paper presented at the 9th EuroConference on Ionics, Ixia, Rhodes, Greece, Sept. 15 – 21, 2002. 相似文献
993.
I. Longo D. Cros N. Tosoratti 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,23(2):273-277
We present a numerical and experimental characterization of high-Q whispering gallery resonant modes excited in a fused quartz spherical shell operated in the 18-26.5 GHz band; easy coupling
and selection of modes is a most advantageous feature of the proposed structure with respect to ordinary bulk resonators.
The numerical results, based on a finite element algorithm, well match experimental data, which also show the capability of
our device to perform gaseous spectroscopy measurements.
Received 25 October 2002 Published online 4 February 2003 相似文献
994.
E. I. Ölmez D. Kut A. N. Bilge I. Ölmez 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):227-231
In ambient air, arsenic to selenium ratio (As/Se) is generally found to be less than 1, except in areas influenced by specific
point sources, such as Cu smelters. However, the annual average of this ratio is found to be much higher than unity in Turkey.
This finding is rather unique and may provide a marker for air masses influenced by the coal-related emissions in Turkey.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
995.
L. D. Popov 《Central European Journal of Mathematics》2004,2(1):76-86
For a linear complementarity problem with inconsistent system of constraints a notion of quasi-solution of Tschebyshev type
is introduced. It’s shown that this solution can be obtained automatically by Lemke’s method if the constraint matrix of the
original problem is copositive plus or belongs to the intersection of matrix classes P
0 and Q
0. 相似文献
996.
Here we prove a limit theorem in the sense of the weak convergence of probability measures in the space of meromorphic functions
for a general Dirichlet series. The explicit form of the limit measure in this theorem is given.
Partially supported by Lithuanian Foundation of Studies and Science 相似文献
997.
In the paper the asymptotics for Dirichlet polynomials associated to certain cusp forms are obtained.
Partially supported by Lithuanian Foundation of Studies and Science 相似文献
998.
E. V. Radkevich 《Journal of Mathematical Sciences》2004,123(5):4428-4455
The paper is devoted to the study of the asymptotic behavior of solutions to linearized systems of equations of the so-called nonequilibrium thermodynamic moments. 相似文献
999.
E. A. Sopkina 《Journal of Mathematical Sciences》2004,124(1):4832-4836
An invariant of a closed set that is equal to the sum of roots is introduced. For a closed subset in a root system, we describe symmetric and special parts and its stabilizer in the Weyl group by means of the sum of roots. We determine associated bases with respect to which the closed set has the simplest form. All possible values of the root sum are found. Bibliography: 9 titles. 相似文献
1000.
David E. Anderson 《Proceedings of the American Mathematical Society》2004,132(9):2517-2527
With an explicit example, we confirm a conjecture by Neumann and Wahl that there exist cusps with no Galois cover by a complete intersection. Some computational techniques are reviewed, and a method for deciding whether a given cusp has a complete intersection Galois cover is developed.