Pressure‐amplitude reflection coefficients of active impedance tube terminations and their relationships to energy‐related quantities of adjacent sound fields

2000 ◽  
Vol 108 (5) ◽  
pp. 2513-2513
Author(s):  
Timothy W. Leishman
Keyword(s):  
Reflection Coefficients ◽  
Pressure Amplitude ◽  
Impedance Tube ◽  
Sound Fields ◽  
Active Impedance ◽  
Amplitude Reflection

scholarly journals Electromagnetic Reflection from Multi-Layered Snow Models

1975 ◽  
Vol 14 (72) ◽  
pp. 501-515 ◽  
Author(s):  
William I. Linlor ◽  
George R. Jiracek
Keyword(s):  
Water Resource Management ◽  
Plane Waves ◽  
Electromagnetic Response ◽  
Effective Dielectric Constant ◽  
Reflection Coefficients ◽  
Snow Layer ◽  
Flood Prediction ◽  
Incident Plane ◽  
Simplifying Assumptions ◽  
Amplitude Reflection

The remote sensing of snow-pack characteristics with surface installations or an airborne system could have important applications in water-resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multi-layered snow models is analyzed in this paper. Normally incident plane waves at frequencies ranging from 106 to 1010 Hz are assumed, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice layers. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the variations of reflection coefficient as a function of frequency.

scholarly journals Electromagnetic Reflection from Multi-Layered Snow Models

1975 ◽  
Vol 14 (72) ◽  
pp. 501-515
Author(s):  
William I. Linlor ◽  
George R. Jiracek
Keyword(s):  
Water Resource Management ◽  
Plane Waves ◽  
Electromagnetic Response ◽  
Effective Dielectric Constant ◽  
Reflection Coefficients ◽  
Snow Layer ◽  
Flood Prediction ◽  
Incident Plane ◽  
Simplifying Assumptions ◽  
Amplitude Reflection

The remote sensing of snow-pack characteristics with surface installations or an airborne system could have important applications in water-resource management and flood prediction. To derive some insight into such applications, the electromagnetic response of multi-layered snow models is analyzed in this paper. Normally incident plane waves at frequencies ranging from 106 to 1010 Hz are assumed, and amplitude reflection coefficients are calculated for models having various snow-layer combinations, including ice layers. Layers are defined by a thickness, permittivity, and conductivity; the electrical parameters are constant or prescribed functions of frequency. To illustrate the effect of various layering combinations, results are given in the form of curves of amplitude reflection coefficients versus frequency for a variety of models. Under simplifying assumptions, the snow thickness and effective dielectric constant can be estimated from the variations of reflection coefficient as a function of frequency.

Reflection Coefficients at Collagen Interfaces in Soft Tissues

1979 ◽  
Vol 1 (4) ◽  
pp. 346-355 ◽  
Author(s):  
Avtar S. Ahuja
Keyword(s):  
Normal Tissue ◽  
Elastic Moduli ◽  
Soft Tissues ◽  
Reflection Coefficients ◽  
Body Model ◽  
The Matrix ◽  
Correlation Parameters ◽  
Tissue Matrix ◽  
Amplitude Reflection

For the purpose of ultrasonic imaging, soft tissue has been modeled as a viscoelastic (Voigt) composite material consisting of collagen fibers (as the inhomogeneity) embedded in a continuum tissue (as the matrix). It is known that infarction enhances the collagen content in myocardial tissues. The published in vitro attenuation data in normal and infarcted myocardial tissues have been correlated with the Voigt body model. From the correlation parameters and mixture laws for the elastic moduli of tissue components, the bulk modulus of collagen has been estimated to be about 50–55% higher than that of the normal tissue. From a knowledge of the bulk moduli and mass densities of collagen and tissue matrix, amplitude reflection coefficients at collagen interfaces have been computed. The amplitude reflection coefficient at the saline-collagen or at the collagen-myocardium interface is about 6 times that at the saline-myocardium interface.

Nonlinear dynamics of a shell encapsulated microbubble near solid boundary in an ultrasonic field

2020 ◽  
Vol 14 (3) ◽  
pp. 7235-7243
Author(s):  
N.M. Ali ◽  
F. Dzaharudin ◽  
E.A. Alias
Keyword(s):  
Oscillation Amplitude ◽  
Ultrasonic Field ◽  
Dynamical Behaviour ◽  
Ultrasound Contrast Agents ◽  
Chaotic Behaviour ◽  
Solid Boundary ◽  
Driving Frequency ◽  
Pressure Amplitude ◽  
Radial Expansion ◽  
Therapeutic Delivery

Microbubbles have the potential to be used for diagnostic imaging and therapeutic delivery. However, the transition from microbubbles currently being used as ultrasound contrast agents to achieve its’ potentials in the biomedical field requires more in depth understanding. Of particular importance is the influence of microbubble encapsulation of a microbubble near a vessel wall on the dynamical behaviour as it stabilizes the bubble. However, many bubble studies do not consider shell encapsulation in their studies. In this work, the dynamics of an encapsulated microbubble near a boundary was studied by numerically solving the governing equations for microbubble oscillation. In order to elucidate the effects of a boundary to the non-linear microbubble oscillation the separation distances between microbubble will be varied along with the acoustic driving. The complex nonlinear vibration response was studied in terms of bifurcation diagrams and the maximum radial expansion. It was found that the increase in distance between the boundary and the encapsulated bubble will increase the oscillation amplitude. When the value of pressure amplitude increased the single bubble is more likely to exhibit the chaotic behaviour and maximum radius also increase as the inter wall-bubble distance is gradually increased. While, with higher driving frequency the maximum radial expansion decreases and suppress the chaotic behaviour.

Predictability of Deterministic Underwater Sound Fields

1993 ◽  
Author(s):  
Michael G. Brown ◽  
Frederick D. Tappert
Keyword(s):  
Underwater Sound ◽  
Sound Fields
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