Two-Dimensional Airborne Position and Velocity Measurements Using a Pair of Linear-Period-Modulated Ultrasonic Waves

2016 ◽  
Vol 102 (4) ◽  
pp. 688-695
Author(s):  
N. Thong-un ◽  
S. Saito ◽  
S. Hirata ◽  
Y. Orino ◽  
M. K. Kurosawa
Keyword(s):  
Ultrasonic Waves ◽  
Two Dimensional ◽  
Velocity Measurements ◽  
Linear Period

scholarly journals Three-dimensional position and velocity measurements using a pair of linear-period-modulated ultrasonic waves

2013 ◽  
Vol 34 (3) ◽  
pp. 233-236 ◽  
Author(s):  
Natee Thong-un ◽  
Shinnosuke Hirata ◽  
Minoru K. Kurosawa ◽  
Yuishiro Orino
Keyword(s):  
Three Dimensional ◽  
Ultrasonic Waves ◽  
Velocity Measurements ◽  
Linear Period

scholarly journals Analytic reconstruction of a two-dimensional velocity field from an observed diffusive scalar

2019 ◽  
Vol 871 ◽  
pp. 755-774
Author(s):  
Arjun Sharma ◽  
Irina I. Rypina ◽  
Ruth Musgrave ◽  
George Haller
Keyword(s):  
Velocity Field ◽  
Ocean Circulation ◽  
Incompressible Flows ◽  
Circulation Model ◽  
Scalar Fields ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Velocity Measurements ◽  
Ocean Circulation Model ◽  
Spatial Domains

Inverting an evolving diffusive scalar field to reconstruct the underlying velocity field is an underdetermined problem. Here we show, however, that for two-dimensional incompressible flows, this inverse problem can still be uniquely solved if high-resolution tracer measurements, as well as velocity measurements along a curve transverse to the instantaneous scalar contours, are available. Such measurements enable solving a system of partial differential equations for the velocity components by the method of characteristics. If the value of the scalar diffusivity is known, then knowledge of just one velocity component along a transverse initial curve is sufficient. These conclusions extend to the shallow-water equations and to flows with spatially dependent diffusivity. We illustrate our results on velocity reconstruction from tracer fields for planar Navier–Stokes flows and for a barotropic ocean circulation model. We also discuss the use of the proposed velocity reconstruction in oceanographic applications to extend localized velocity measurements to larger spatial domains with the help of remotely sensed scalar fields.

A study on nonlinear ultrasonic waves in bubbly media: One and two‐dimensional numerical experiments.

2010 ◽  
Vol 127 (3) ◽  
pp. 1985-1985
Author(s):  
Vanhille Christian ◽  
Campos‐Pozuelo Cleofé
Keyword(s):  
Numerical Experiments ◽  
Ultrasonic Waves ◽  
Two Dimensional ◽  
Nonlinear Ultrasonic

A Note on the Estimation of Average Pressures from Instantaneous Velocities in Unsteady Flow

1967 ◽  
Vol 71 (678) ◽  
pp. 440-440
Author(s):  
C. J. Wood
Keyword(s):  
Unsteady Flow ◽  
Boundary Layers ◽  
Data Reduction ◽  
Bluff Body ◽  
Wake Vortex ◽  
Two Dimensional ◽  
Experimental Check ◽  
Velocity Measurements ◽  
Periodic Disturbance ◽  
Oncoming Stream

In a recent paper, the author described some experiments in which the average base pressure on a two-dimensional bluff body was estimated from a random sample of instantaneous velocity measurements taken in the irrotational flow outside the separating boundary layers at the trailing edge. Although the oncoming stream was steady, the flow near the model was subject to a periodic disturbance emanating from the wake vortex street. An experimental check showed that the pressure estimates obtained by using the steady Bernouilli equation were reasonably accurate. This note points out that the method of data reduction used in ref. 1 is not an approximation; it is exact.

Theoretical Approach to Contrast Mechanism for U-AFM

2002 ◽  
Author(s):  
C. Miyasaka ◽  
B. R. Tittmann ◽  
T. Adachi ◽  
A. Yamaji
Keyword(s):  
Theoretical Analysis ◽  
Resonant Frequency ◽  
Atomic Force Microscope ◽  
Dynamic Theory ◽  
Beam Theory ◽  
Ultrasonic Waves ◽  
Two Dimensional ◽  
Atomic Force ◽  
Afm Imaging ◽  
Contrast Mechanism

When the Ultrasonic-Atomic Force Microscope (U-AFM) is used to form an image of a surface of a specimen having discontinuities, contrast of the specimen in the image is usually stronger than that of an image formed by a conventional Atomic Force Microscope (AFM). In this article, the mechanism of the contrast of the image obtained by the U-AFM was explained by theoretical analysis. A ceramic and metal jointed bar (Steel/Cu/Si3N4) was selected as a specimen for this study. The specimen was located on the surface of a disc transducer generating ultrasonic waves up to 500 KHz, and was vibrated, wherein its first resonant frequency was 133.43 kHz. Both stress and displacement of the specimen were analyzed by classical beam theory and the two-dimensional elasto-dynamic theory. Experimental U-AFM imaging analyses were also carried out to compare the results.

scholarly journals Doppler Velocity Estimation of Overlapping Linear-Period-Modulated Ultrasonic Waves Based on an Expectation-Maximization Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Natee Thong-un ◽  
Minoru K. Kurosawa
Keyword(s):  
Em Algorithm ◽  
Expectation Maximization ◽  
Pulse Compression ◽  
Moving Objects ◽  
Expectation Maximization Algorithm ◽  
Ultrasonic Waves ◽  
Velocity Estimation ◽  
Doppler Velocity ◽  
The Em Algorithm ◽  
Linear Period

The occurrence of an overlapping signal is a significant problem in performing multiple objects localization. Doppler velocity is sensitive to the echo shape and is also able to be connected to the physical properties of moving objects, especially for a pulse compression ultrasonic signal. The expectation-maximization (EM) algorithm has the ability to achieve signal separation. Thus, applying the EM algorithm to the overlapping pulse compression signals is of interest. This paper describes a proposed method, based on the EM algorithm, of Doppler velocity estimation for overlapping linear-period-modulated (LPM) ultrasonic signals. Simulations are used to validate the proposed method.

Experimental and theoretical investigations of focusing of ultrasonic waves by two‐dimensional flat phononic crystals

2008 ◽  
Vol 123 (5) ◽  
pp. 3281-3281 ◽  
Author(s):  
Alexey Sukhovich ◽  
John H. Page ◽  
Bassam Merheb ◽  
Jérôme Vasseur ◽  
Pierre Deymier
Keyword(s):  
Ultrasonic Waves ◽  
Phononic Crystals ◽  
Two Dimensional ◽  
Theoretical Investigations

Thermal switching of ultrasonic waves in two-dimensional solid/fluid phononic crystals

2019 ◽  
Vol 94 (12) ◽  
pp. 125705 ◽  
Author(s):  
Mehran Alinejad-Naini ◽  
Ali Bahrami
Keyword(s):  
Ultrasonic Waves ◽  
Phononic Crystals ◽  
Two Dimensional ◽  
Thermal Switching
Sign in / Sign up

Export Citation Format

Share Document