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901.
S. P. Bautin 《Journal of Applied Mechanics and Technical Physics》2009,50(4):576-583
The Kuropatenko model for a multicomponent medium whose components are polytropic gases is considered. It is assumed that,
as x → ±∞, the multicomponent medium is in a homogeneous state with constant gas-dynamic parameters — velocity, pressure,
and temperature. For the traveling wave flows, conditions similar to the Hugoniot conditions are obtained and used to uniquely
determine the flow parameters for x → −∞ from the flow parameters x → +∞ and traveling wave velocity.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 4, pp. 39–47, July–August, 2009. 相似文献
902.
San-jun ZHANG Lotfi BERGUIGA Nicolas HUGO Thibault ROLAND Francoise ARGOUL Juan ELEZGARAY Wen-xueLI He-ping ZENG 《Frontiers of Physics》2009,4(4):469
This article reviews our recent advances in surface plasmon resonance (SPR) based biochips. It includes four issues, which are the preparation and characterization of high quality gold film, the preparation and characterization of self-assembled monolayer (SAM), dynamics of DNA adsorption on SAMs, and SPRbased microscopies. Numerous topics related to SPR, such as, the modeling of SPR by transmission matrix, effective medium theory, applications of SPR in biology, and SPR-based novel microscopies, are discussed. A novel electrochemical technique, which is extremely useful for the preparation and characterization of high quality SAMs, is also discussed. 相似文献
903.
This research addresses the investigation of an elastic wave field in a homogeneous and isotropic porous medium which is fully
saturated by a Newtonian viscous fluid. A new methodology is developed for describing the wave field in the medium excited
by multiple energy sources. To quantify the relative displacements between the fluid and solid of the medium, the governing
equations of the elastic wave propagation are derived in the form of displacements specially. The velocities and attenuation
of the waves are considered as functions of viscosity and frequency. Making use of the Hankel function and the moving-coordinate
method, a model of the wave motion with multiple cylindrical wave sources is built. Making use of the model established in
this research, the relative displacement between the fluid and the solid can be quantified, and the wave field in the porous
media can then be determined with the given energy sources. Numerical simulations of cylindrical waves from multiple energy
sources propagating in the porous medium saturated by viscous fluid are performed for demonstrating the practicability of
the model developed. 相似文献
904.
The steady mixed convection boundary-layer flow over a vertical impermeable surface in a porous medium saturated with water
close to its maximum density is considered for uniform wall temperature and outer flow. The problem can be reduced to similarity
form and the resulting equations are examined in terms of a mixed convection parameter λ and a parameter δ which measures
the difference between the ambient temperature and the temperature at the maximum density. Both assisting (λ > 0) and opposing
flows (λ < 0) are considered. A value δ0 is found for which there are dual solutions for a range λc < λ < 0 of λ (the value of λc dependent on δ) and single solutions for all λ ≥ 0. Another value of δ1 of δ, with δ1 > δ0, is found for which there are dual solutions for a range 0 < λ < λc of positive values of λ, with solutions for all λ≤ 0. There is also a range δ0 < δ < δ1 where there are solutions only for a finite range of λ, with critical points at both positive and negative values of λ, thus
putting a finite limit on the range of existence of solutions. 相似文献
905.
Extending the polarization saturation model [Gao et al., 1997. Local and global energy release rates for an electrically yielded crack in a piezoelectric ceramic. J. Mech. Phys. Solids 45, 491-510] and the dielectric breakdown (DB) model [Zhang et al., 2005. The strip dielectric breakdown model. Int. J. Fract. 132, 311-327] in piezoelectric materials, the Strip Electric-Magnetic Breakdown (SEMB) model is proposed for electrically and magnetically impermeable crack in a magnetoelectroelastic medium to study the effect of the nonlinear character of electric field and magnetic field on fracture of magnetoelectroelastic materials. In the SEMB model, the electric field in the strip of the electric breakdown zone ahead of the crack tip is equal to the electric breakdown strength, while the magnetic filed in the strip of the magnetic breakdown zone is equal to the magnetic breakdown strength. By using the extended Stroh formalism and the extended dislocation modeling of a crack, the Griffith crack problem under the electrically and magnetically elastic-plastic condition in a magnetoelectroelastic medium is reduced to a set of dual integral equations. The sizes of the electric breakdown zone and the magnetic breakdown zone, the extended intensity factors and the local J-integral are obtained. The effect of the combined mechanical-electric-magnetic loadings on the local J-integral is studied. 相似文献
906.
Ibrahim A. Abbas Abo-el-nour N. Abd-alla 《Archive of Applied Mechanics (Ingenieur Archiv)》2008,78(4):283-293
Thermoelastic interactions in an infinite orthotropic elastic medium with a cylindrical cavity are studied. The cavity surface
is subjected to ramp-type heating of its internal boundary, which is assumed to be traction free. Lord–Shulman and Green–Lindsay
models for the generalized thermoelasticity theories are selected since they allow for second-sound effects and reduce to
the classical model for an appropriate choice of the parameters. The temperature, radial displacement, radial stress, and
hoop stress distributions are computed numerically using the finite-element method (FEM). The results are presented graphically
for different values of the thermal relaxation times using the three different theories of generalized thermoelasticity. Excellent
agreement is found between the finite-element analysis and analytical and classical solutions. 相似文献
907.
采用室温溅射加后续退火工艺制备了ZnO∶ Al透明导电薄膜.研究了热处理工艺对薄膜微观结构和光电性能的影响.研究表明:退火有助于减小Al~(3+)对Zn~(2+)的取代造成的晶格畸变,消除应力,促进晶粒长大,有效提高电子浓度和迁移率,降低电阻率;当溅射功率为80 W、退火温度为320 ℃时,薄膜的电阻率可低至8.6×10~(-4) Ω·cm;退火气氛对薄膜的导电性能有较大影响,真空退火可使吸附氧脱附,大大降低薄膜的方块电阻.而退火温度和退火气氛均对ZnO∶ Al薄膜的透光率没有明显影响,薄膜的透光率在86;以上. 相似文献
908.
We consider the problem of finding the transversely isotropic elasticity tensor closest to a given elasticity tensor with
respect to the Frobenius norm. A similar problem was considered by other authors and solved analytically assuming a fixed
orientation of the natural coordinate system of the transversely isotropic tensor. In this paper we formulate a method for
finding the optimal orientation of the coordinate system—the one that produces the shortest distance. The optimization problem
reduces to finding the absolute maximum of a homogeneous eighth-degree polynomial on a two-dimensional sphere. This formulation
allows us a convenient visualization of local extrema, and enables us to find the closest transversely isotropic tensor numerically.
相似文献
909.
α decay energies of 323 heavy nuclei with Z≥82 are evaluated with a macroscopic-microscopic model.In this model,the macroscopic part is treated by the continuous medium model and the microscopic part consists of shell and pairing corrections based on the Nilsson potential.α decay half-lives are calculated by Viola-Seaborg formula.The results of α decay energies and half-lives are compared with experimental values and satisfactory agreement is found.The recoiling effect of the daughter nucleus on α decay half-life is also discussed. 相似文献
910.
M. K. PARTHA 《应用数学和力学(英文版)》2010,31(5):565-574
In this paper, the natural convection in a non-Darcy porous medium is studied using a temperature-concentration-dependent density relation. The effect of the two parameters responsible for the nonlinear convection is analyzed for different values of the inertial parameter, dispersion parameters, Rayleigh number, Lewis number, Soret number, and Dufour number. In the aiding buoyancy, the tangential velocity increases steeply with an increase in the nonlinear temperature parameter and the nonlinear concentration parameter when the inertial effect is zero. However, when the inertial effect is non-zero, the effect of the nonlinear temperature parameter and the nonlinear concentration parameter on the tangential velocity is marginal. The concentration distribution varies appreciably and spreads in different ranges for different values of the double dispersion parameters, the inertial effect parameter, and also for the parameters which control the nonlinear temperature and the nonlinear concentration. Heat and mass transfer varies extensively with an increase in the nonlinear temperature parameter and the nonlinear concentration parameter depending on Dacry and non-Darcy porous media. The variation in heat and mass transfer when all the effects, i.e., the inertial effect, double dispersion ef- fects, and Soret and Dufour effects, are simultaneously zero and non-zero. The combined effects of the nonlinear temperature parameter, the nonlinear concentration parameter and buoyancy are analyzed. The effect of the nonlinear temperature parameter and the nonlinear concentration parameter and also the cross diffusion effects on heat and mass transfer are observed to be more in Darcy porous media compared with those in non- Darcy porous media. In the opposing buoyancy, the effect of the temperature parameter is to increase the heat and mass transfer rate, whereas that of the concentration parameter is to decrease. 相似文献