On the correlation theory of the back-scattering field in a magnetically active plasma

Acoustic methods belong to contactless measurement means, possess high spatial and time resolution. Thus, the use of multifrequency allows directly profile both concentration and granulometric structure of the suspended substances. In 2008 in the Big Wave Flume (Hanover, Germany) by efforts of the Russian and German scientists there have been carried out the experiment on studying the bottom material suspension laws under the influence of irregular waves. The Aquascat 1000 acoustic back scattering sensor (ABS) manufactured by British company Aquatec (www.aquatecsubsea.com), equipped by a three-frequency transmitter with frequencies 1,0, 2,0 and 3,84 MHz, has been set on distance of 0,75 m from the bottom and 111 m from wave generator at the total depth of 3,2 m. Several dozen series of measurements at various parameters of surface waves have been carried out. The general picture of suspension is so that the external dynamic influence (currents, wave movements, turbulence, gravitation forces) creates a non-uniform field (gradient) of the suspended particles and in most cases due to this the average size of particles undergoes to the spatial-time variations. For this reason while defining the mass concentration of suspended sediment, using the single frequency transmitter there is necessity for numerous definition of the suspension granulometric structure what by isn’t always possible. If two and more frequencies are used the observed results comparison can give the information on average diameters of particles and on that basis the calculation of suspended sediment concentration is possibleLet's emphasize the basic advantages of back scattering acoustic gauges usage: – Obtaining the particles sizes and concentration distribution profiles is possible; – The initial granulometric structure of bottom sediments can be unknown (at use of several frequencies). The following can be referred to some lacks of the device: – The system should be calibrated in laboratory conditions; – In a positive feedback conditions the iterative computing process can converge to zero or to infinity. In this case experiments with a variation of carrier frequencies chosen for the analysis allow partially solve the problem (say experiments with different frequencies pairs, as 2/1 of MHz or 4/2 MHz).

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The study of acoustic scattering from a single sound-permeable sphere

Multiphase Systems ◽

10.21662/mfs2018.4.012 ◽

2018 ◽

Vol 13 (4) ◽

pp. 79-91 ◽

Cited By ~ 1

Author(s):

E.Sh. Nasibullaeva

Keyword(s):

Speed Of Sound ◽

Numerical Technique ◽

Acoustic Scattering ◽

Computer Time ◽

Physical Parameters ◽

Fast Method ◽

Scattering Field ◽

Permeable Sphere ◽

Test Verification ◽

Good Agreement

The paper presents a generalized mathematical model and numerical investigation of the problem of acoustic scattering from a single sound-permeable sphere during the passage of two types of waves - spherical from a monopole radiation source and a plane one. In solving the Helmholtz equation, a numerical technique based on the fast method of multipoles is used, which allows achieving high accuracy of the results obtained at the lowest cost of computer time. The calculations are compared with known experimental data and a good agreement is obtained. The formulas for calculating the main characteristic of the scattering field (the total scattering cross section) for a sound-permeable sphere are generalized. The effect on this characteristic of the physical parameters of media outside and inside the sphere, such as the density and speed of sound, is shown. A numerical parametric analysis of the pressure distribution around a single sound-permeable sphere for different values of the wave radius, density, and speed of sound of the outer and inner medium of the sphere is carried out. The obtained results will later be used for test verification calculations for the numerical solution of the generalized problem of acoustic scattering of a set of sound-permeable spheres (coaxial or arbitrarily located in space).

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Color Etching for Characterization the Grain Orientation in Spheroidal Graphite Cast Iron

Materials Science Forum ◽

10.4028/www.scientific.net/msf.537-538.389 ◽

2007 ◽

Vol 537-538 ◽

pp. 389-396 ◽

Cited By ~ 2

Author(s):

Ibolya Kardos ◽

Zoltán Gácsi ◽

Péter János Szabó

Keyword(s):

Cast Iron ◽

Crystallographic Orientation ◽

Grain Orientation ◽

Test Material ◽

Spheroidal Graphite ◽

Metallic Materials ◽

Additional Information ◽

Spheroidal Graphite Cast Iron ◽

Graphite Cast Iron ◽

Back Scattering

Color etching is a widely used technique for visualizing different phases in metallic materials. Its advantage to the traditional etching techniques is that it gives additional information within one phase, namely, the color shade of a given phase can change in a certain range. This paper demonstrates that, due to the physics of the color etching, the shade of a phase also depends on the crystallographic orientation of the investigated grain. As a test material, spheroidal graphite cast iron was used, and individual grain orientation was identified by automated electron back scattering diffraction (EBSD). Results showed that there is a strong correlation between grain orientation and the shades obtained by color etching.

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Studies of inhomogeneous substances by ultrasonic back-scattering

Ultrasound in Medicine & Biology ◽

10.1016/0301-5629(76)90037-5 ◽

1976 ◽

Vol 2 (3) ◽

pp. 195-198 ◽

Cited By ~ 12

Author(s):

B. Fay ◽

K. Brendel ◽

G. Ludwig

Keyword(s):

Back Scattering

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