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81.
I.IntroductionAnidealplanarsurroundsoundsystemshouldreproduceanaturalanddistinctimageandshouldnothavetheeffectofAnagepositi9ndistortion.Itshouldalsohaveagoodeffectoverawidelisteningarea)agoodcompatibilitywith8tereosystem.ItshouldnotrequiremanytransInissionchannels.InthispaPeritisproposedthataseriesofplanarsurroundsoundsystemstomeetaboverequlremellts.II-ThereproductionsignalsoftheperfectplanarsurroundsoundsystemFirstthecharacteristicsofaperfectplanarsurroundsoundsystemareanalysed.There-prod… 相似文献
82.
Precision densities and sound velocities for solutions of selected univalent electrolytes and nonelectrolytes in DMSO have been measured at 25°C, and apparent molar isentropic compressibilities and volumes evaluated. The data were extrapolated to infinite dilution to obtain standard state partial molar quantities, K
s,2
°
, and V
2
°
. Values of V
2
°
and K
s,2
°
for alkali metal halides in DMSO are very similar to those in water. The results confirm conclusions derived from data in water and other nonaqueous solvents that K
s,2
°
and V
2
°
for alkali metal halides are strongly dependent on solvent compressibility. K
s,2
°
becomes more negative and V
2
°
decreases as solvent compressibility increases. Attempts to determine ionic K
s,2
°
values suggest that a significant dissymmetry exists between 4P+ and 4B– in DMSO, whereas in water and MeOH, these large ions appear to behave similarly. Ionic V
2
°
values support this conclusion. Steric hindrance in the DMSO molecule is believed to be responsible for this dissymmetry. 相似文献
83.
声速综合测量仪的设计与应用 总被引:1,自引:0,他引:1
本文分析了声压驻波原理,介绍了声速综合测量仪的设计方法,并给出了较精确的测量结果。 相似文献
84.
85.
在驻波法测定声速实验中,根据发射器和接收器之间合成声场的位移波动方程和声压波动方程,用matlab程序模拟了声场和声压的振幅和初相位分布,并对模拟结果进行了分析和讨论。 相似文献
86.
Leppington F. G.; Broadbent E. G.; Butler G. F. 《IMA Journal of Applied Mathematics》2006,71(6):940-955
** Email: f.leppington{at}ukonline.co.uk
Two thin elastic plates, which may have different physical parameters,occupy the parallel regions 0 < x < a, 0 < y < b,z = d and 0 < x < a, 0 < y < b, z = 0, ina Cartesian coordinate system, where the separation distanced is much less than the dimensions a and b. The plates are simplyconnected to a structure that occupies the rest of the region d < z < 0. The side walls (x = 0 or a, 0 <y < b, d < z < 0 and y = 0 or b, 0 < x <a, d < z < 0) are taken to be acoustically soft;the surfaces z = d and z = 0, outside the rectangularregions occupied by the plates, are taken to be acousticallyhard. Light compressible fluid (air) is in each of the half-spacesoutside the plates and in the rectangular region between them.A sound field is induced by a high-frequency plane wave. Allowanceis made for a small element of damping in the fluid trappedbetween the plates, as well as damping in the plates. Estimatesare derived for the transmitted power, averaged over a frequencyband and with respect to all incidence directions, in the asymptoticlimits of small fluid loading and high frequency. For the casewhere the two plates have identical physical properties, detailedasymptotic estimates are given for the form of the peaks inthe transmitted power, at a discrete set of operating frequencies,both above and below the plates' coincidence frequency. 相似文献
87.
A.S. Bonnet-Ben Dhia J.F. Mercier S. Pernet 《Journal of Computational and Applied Mathematics》2010,234(6):1868-1875
This paper concerns the finite element simulation of the diffraction of a time-harmonic acoustic wave in the presence of an arbitrary mean flow. Considering the equation for the perturbation of displacement (due to Galbrun), we derive a low-Mach number formulation of the problem which is proved to be of Fredholm type and is therefore well suited for discretization by classical Lagrange finite elements. Numerical experiments are done in the case of a potential flow for which an exact approach is available, and a good agreement is observed. 相似文献
88.
The Thomas–Fermi approximation gives the Grüneisen parameter γ=γ∞=1/2 for all materials at extreme compression (P→∞ or V→0). After re-analyzing the existing experimental data of volume dependence of Grüneisen parameter γ of hexagonal close-packed (HCP) iron, we find that γ=1/2+a(V/V 0)1/3+b(V/V 0) n , where a, b and n are constants. Based on this new form of γ, the second Grüneisen parameter q, the Debye temperature θD and the shear sound velocity v s of HCP iron are discussed in the present work. It is found that the zero pressure second Grüneisen parameter q 0=0.654, which is consistent with the previously determined value of HCP iron for Earth's core physics from Dubrovinsky et al. The calculations for the Debye temperature and the shear sound velocity are also found to be in good agreement with the experimental data. 相似文献
89.
Belkacem Said-Houari 《Applicable analysis》2013,92(2):424-440
In this article, we investigate the decay properties of the linear thermoelastic plate equations in the whole space for both Fourier and Cattaneo's laws of heat conduction. We point out that while the paradox of infinite propagation speed inherent in Fourier's law is removed by changing to the Cattaneo law, the latter always leads to a loss of regularity of the solution. The main tool used to prove our results is the energy method in the Fourier space together with some integral estimates. We prove the decay estimates for initial data U 0?∈?H s (?)?∩?L 1(?). In addition, by restricting the initial data to U 0?∈?H s (?)?∩?L 1,γ(?) and γ?∈?[0,?1], we can derive faster decay estimates with the decay rate improvement by a factor of t ?γ/2. 相似文献
90.
Marié Grobbelaar-Van Dalsen 《Applicable analysis》2013,92(9):1419-1449
In this article we are concerned with the strong stabilization of models for the Reissner–Mindlin plate equations with second sound, that is, models that include thermal effects described according to Cattaneo's law of heat conduction instead of Fourier's law in classical thermoelasticity. Two models will be considered which are distinct with respect to the property of compactness or non-compactness of the resolvent of the generator of the underlying semigroup. In accordance with the compactness or non-compactness of the resolvent operator, a different criterion for strong stability is implemented to achieve the strong stabilization of each model. In the compact resolvent case we avail ourselves of a result given by Benchimol [C.D. Benchimol, A note on weak stabilizability of contraction semigroups, SIAM J. Control Optim. 16 (1978), pp. 373–379] and in the non-compact case we resort to a stability criterion Tomilov [Y. Tomilov, A resolvent approach to stability of operator semigroups, J. Operator Theory 46 (2001), pp. 63–98]. 相似文献