Using forward scattering from a rippled sand/water interface to determine its flat surface reflection coefficient: Validation via simulation and use in testing sediment models

2006 ◽  
Vol 120 (5) ◽  
pp. 3180-3180
Author(s):  
Kevin Williams
Keyword(s):  
Reflection Coefficient ◽  
Flat Surface ◽  
Forward Scattering ◽  
Water Interface ◽  
Surface Reflection

scholarly journals Enhanced propagation of motile bacteria on surfaces due to forward scattering

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Stanislaw Makarchuk ◽  
Vasco C. Braz ◽  
Nuno A. M. Araújo ◽  
Lena Ciric ◽  
Giorgio Volpe
Keyword(s):  
Biofilm Formation ◽  
Flat Surface ◽  
Experimental Studies ◽  
Forward Scattering ◽  
Bacterial Motility ◽  
Complex Environments ◽  
Natural Habitats ◽  
Near Surface ◽  
Propulsion Mechanism ◽  
Motile Bacteria

Abstract How motile bacteria move near a surface is a problem of fundamental biophysical interest and is key to the emergence of several phenomena of biological, ecological and medical relevance, including biofilm formation. Solid boundaries can strongly influence a cell’s propulsion mechanism, thus leading many flagellated bacteria to describe long circular trajectories stably entrapped by the surface. Experimental studies on near-surface bacterial motility have, however, neglected the fact that real environments have typical microstructures varying on the scale of the cells’ motion. Here, we show that micro-obstacles influence the propagation of peritrichously flagellated bacteria on a flat surface in a non-monotonic way. Instead of hindering it, an optimal, relatively low obstacle density can significantly enhance cells’ propagation on surfaces due to individual forward-scattering events. This finding provides insight on the emerging dynamics of chiral active matter in complex environments and inspires possible routes to control microbial ecology in natural habitats.

Sea Surface Reflection Coefficient Estimation

2013 ◽  
Author(s):  
Okwudili C. Orji ◽  
Walter Sollner ◽  
Leiv J. Gelius
Keyword(s):  
Reflection Coefficient ◽  
Sea Surface ◽  
Surface Reflection ◽  
Coefficient Estimation

Trial for Monitoring the Water Temperature Utilizing the Frequency Dependence of Reflection Coefficient of Ultrasound Passing Through Thin Layer

2019 ◽  
Vol 2 (2) ◽  
Author(s):  
Hironori Tohmyoh ◽  
Shu Terashima
Keyword(s):  
Thin Film ◽  
Reflection Coefficient ◽  
Thin Layer ◽  
Water Temperature ◽  
Acoustic Impedance ◽  
Amplitude Spectrum ◽  
Acoustic Resonance ◽  
Water Interface ◽  
Amplitude Spectra ◽  
The Difference

This paper describes a new concept to monitor the temperature of water utilizing the acoustic resonance, which occurs when ultrasound passes through a thin layer. In the ultrasonic transmission system that comprises of the reflection plate, thin film, and water, the reflection coefficient of the ultrasound at the plate/film/water interface depends on the frequency and takes its minimum value at the resonant frequency. Notably, this is closely related to the acoustic impedance of the water; moreover, it is a known fact that the acoustic impedance of the water demonstrates temperature dependence. Against this background, the present study aims to develop a technique in order to monitor the temperature of water utilizing the aforementioned correlation between the reflection coefficient and water temperature. First, a theoretical model was developed to determine the acoustic impedance of water from the difference in the amplitude spectra of echoes reflected at the back of the plate in the cases both with and without the film. It was found that the ratio of the amplitude spectrum of the echo recorded in the case with the film to that in the case without the film clearly decreased with a drop in water temperature. From this, we obtained the equation for determining water temperature experimentally. Finally, the temperature of water, which was brought down by air or ice cooling, was monitored by the proposed method. It was found that the behavior of temperature determined by the proposed method was congruent with that which was measured by a thermocouple.

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