Asymptotic expansions for small Strouhal number, valid for arbitrary subsonic Mach number, are derived for the solution of a simple problem of the interaction between an acoustic wave, a jet flow and a pipe, based on Munt's [ l ] exact formal solution. These expansions relate to the pressure and velocity fluctuations in the jet flow and in the far field, and to the reflection coefficient, end-i...

An ultrasonic reflected wave at oblique incidence by porous medium with rigid frames is considered using equivalent fluid model. The viscous and thermal losses of the medium are described by two susceptibility kernels which depend on the viscous and thermal characteristic lengths. Analytical derivation of reflection coefficient is given in frequency domain. The simulated reflected wave is obtai...

We have studied niobium superconducting thin wires deposited onto a SrTiO3 substrate. By measuring the reflection coefficient of the wires, resonances are observed in the superconducting state in the 130 MHz to 4 GHz range. They are interpreted as standing wave resonances of one-dimensional plasma modes propagating along the superconducting wire. The experimental dispersion law, omega versus q,...

We study the scattering of an incident wave by a composite medium with periodic microstructure in a slab geometry. We compute the expansion on the wave field in powers of the parameter = d/λ, where d is the characteristic scale of the microstructure and λ is the wavelength. For ε = 0 this corresponds to homogenization theory. Here, we focus on the correction terms for ε > 0 and compute the freq...

In this study, a sandwich beam with periodic multiple dissipative resonators in the sandwich core material is investigated for broadband wave mitigation and/or absorption. An analytical approach based on the transfer matrix method and Bloch theorem is developed for both infinite and finite sandwich structures. Wave attenuation constants are theoretically obtained to examine the effects of vario...

BACKGROUND Elevated blood pressure is the leading modifiable risk factor for cardiovascular disease (CVD) and premature death. The blood pressure waveform consists of discrete hemodynamic components, derived from measured central pressure and flow, which may contribute separately to risk for an adverse outcome. However, pressure-flow measures have not been studied in a large, community-based sa...

acetylation is a chemical modification of wood to enhance its properties. ir-spectroscopy is a useful technique for proofing chemical bondings in wood and the at-tenuated total reflection (atr) infrared spectroscopy technique was applied as an eas-ier technique over other ir-spectroscopies. in this research, different degrees of acetyla-tion, weight percentage gains (wpgs) in beech and pine min...

By means of the Kedem-Katchalsky thermodynamic description of active transport, a relationship has been derived between the apparent reflection coefficient and the Staverman reflection coefficient for passive transport of a solute which is both actively and passively transported. The relationship between volumetric flow and its driving forces, containing the Staverman reflection coefficient, wa...

An estimate is derived for the error committed by the introduction of artificial boundaries and corresponding artificial boundary conditions when solving wave equations on unbounded domains. The estimate has two terms. One is proportional to the largest reflection coefficient for the artificial boundary condition, the maximum taken only on those rays which appear in the computation. The second ...