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991.
We consider a degenerate abstract wave equation with a time-dependent propagation speed. We investigate the influence of a strong dissipation, namely a friction term that depends on a power of the elastic operator.We discover a threshold effect. If the propagation speed is regular enough, then the damping prevails, and therefore the initial value problem is well-posed in Sobolev spaces. Solutions also exhibit a regularizing effect analogous to parabolic problems. As expected, the stronger is the damping, the lower is the required regularity.On the contrary, if the propagation speed is not regular enough, there are examples where the damping is ineffective, and the dissipative equation behaves as the non-dissipative one. 相似文献
992.
We consider the Cauchy problem in R n for strongly damped Klein‐Gordon equations. We derive asymptotic profiles of solutions with weighted L1,1( R n) initial data by a simple method introduced by the second author. Furthermore, from the obtained asymptotic profile, we get the optimal decay order of the L2‐norm of solutions. The obtained results show that the wave effect will be relatively weak because of the mass term, especially in the low‐dimensional case (n = 1,2) as compared with the strongly damped wave equations without mass term (m = 0), so the most interesting topic in this paper is the n = 1,2 cases to compare the difference. 相似文献
993.
The dependence of the damping characteristics of axisymmetric tri-sectional flight vehicles executing plane oscillations about the zero angle of attack on their geometric parameters is investigated on the supersonic range of uniform oncoming air flow Mach numbers. Systematic data are obtained using the least laborious approach, namely, by calculating the steady-state inviscid flow past equivalent bodies determined from the principle of the local similarity of force interaction. Ranges of the vehicle design parameters on which the dependence of the damping moment coefficient in pitch on the length of the conical or cylindrical-conical stabilizer of the vehicle is nonmonotonic are found. Typical viscosity effects on the characteristics under study are estimated using a method based on the assumptions of the linear theory for finite-thickness bodies. It is established that the damping coefficient increases monotonically with decreasing Reynolds number; moreover, even transition to oscillation antidumping regimes is possible when the sign of the damping coefficient changes.Translated from Izvestiya Rossiiskoi Academii Nauk, Mekhanika Zhidkosti i Gaza, No. 6, 2004, pp. 153–162. Original Russian Text Copyright © 2004 by Antonets and Shmanenkov. 相似文献
994.
995.
Treating a black hole as a relativistic gas of microblack holes (planckions) which have fermionic character, expressions for
some thermodynamic quantities are obtained. These have the same structure as those obtained by Hawking by other considerations. 相似文献
996.
From the results of an analysis of the viscoelastic characteristics of semi-interpenetrating polymer networks (semi-IPNs)
that are based on a crosslinked polyurethane and a linear polystyrene and are formed in the presence of compatibilizing additives
(oligourethane dimethacrylate and ethylene glycol monomethacrylate), their damping ability is est mated. Such parameters as
the tangent of mechanical loss (tan δ) at the glass-transition temperature, the temperature interval of effective damping
(where tan δ > 0.3), and the loss area under the loss modulus vs. temperature plots are used as the criteria of damping ability.
It is shown that the introduction of the compatibilizing additives to the semi-IPNs extends the interval of their effective
damping temperature. By varying the composition of the material and the amount of the compatibilizing additives, it is possible
to realize a purposeful selection of vibration-damping materials for solving specific technological problems.
__________
Translated from Mekhanika Kompozitnykh Materialov, Vol. 42, No. 4, pp. 545–558, July–August, 2006. 相似文献
997.
在相对论连续谱Hartree Bogoliubov(RCHB)理论框架下,在质子数Z=100—140和中子数N=Z+30—2Z+32等偶偶核中进行了超重球形双幻核的探索.采用的有效相互作用为NL1,NL3,NLSH,TM1,TW 99,DD ME1,PK1和PK1R.基于对双核子分离能(S2p和S2n)、双核子能隙(δ2p和δ2n)、壳修正能量(Epshell)、对能(Eppair和Enpair)和有效对能隙(Δp和Δn)等物理量和能shell和En级结构的分析,预言了可能的质子幻数和中子幻数,并观察到在超重核区壳的弱化现象. The magic proton and neutron numbers are searched in the superheavy region with proton number Z=100 —140 and neutron number N=(Z+30) — (2Z+32) by the relativistic continuum Hartree-Bogoliubov (RCHB) theory with interactions NL1, NL3, NLSH, TM1, TW99, DD-ME1, PK1, and PK1R. Based on the two-nucleon separation energies S_(2p )and S_(2n) , the two-nucleon gaps δ_(2p) and δ_(2n), the shell correction energies E~p_(shell) and E~n_(shell), the pairing energies E~p_(pair) and E~n_(pair), and... 相似文献
998.
V.F. Radantsev V.V. Kruzhaev 《Physica E: Low-dimensional Systems and Nanostructures》2006,34(1-2):340
The Rashba spin–orbit splitting of 2D electron gas in gated HgCdTe surface quantum wells on n-HgCdTe is studied experimentally (by the magneto-capacitance spectroscopy of Landau level method) and theoretically with emphasis on the peculiarities of spectrum at surface densities Ns corresponding to the onset of 2D subbands occupancy, where the regime of kinetic binding is realized. Although the spin–orbit splitting in kinetic confinement regime is small, the “Rashba polarization” Δn/n can achieve 100% because of strong difference in values of cutoff wave vector kc for different spin-split sub-subbands. 相似文献
999.
Self-affine multiplicity scaling is investigated in the framework of a two-dimensional factorial mo-ment methodology using the concept of the Hurst exponent (H). Investigation of the experimental data of medium-energy knocked-out target protons in SaKr-AgBr interactions at 1.7 AGeV reveals that the best power law behavior is exhibited for H = 0.4, indicating a self-affine multiplicity fluctuation pattern. Multifractalit yamong the knocked-out target protons is also observed in the data. 相似文献
1000.
Jong Uhn Kim 《Applied Mathematics and Optimization》2008,58(1):29-67
We discuss an initial boundary value problem for the stochastic wave equation with nonlinear damping. We establish the existence
and uniqueness of a solution. Our method for the existence of pathwise solutions consists of regularization of the equation
and data, the Galerkin approximation and an elementary measure-theoretic argument. We also prove the existence of an invariant
measure when the equation has pure nonlinear damping. 相似文献