scholarly journals On the acoustic disturbances produced by small bodies in plane waves transmitted through water, with special reference to the single-plate direction finder

1921 ◽  
Vol 100 (704) ◽  
pp. 261-288
Keyword(s):  
Special Reference ◽  
Plane Waves ◽  
Maximum Amplitude ◽  
Sound Waves ◽  
Small Bodies ◽  
Acoustic Disturbances ◽  
Sense Of Direction ◽  
Single Plate ◽  
Direction Finder ◽  
Metal Diaphragm

The experiments to be described were carried out for the Board of Invention and Research, under the direction of Sir William Bragg, between October 1916 and February 1917, on the Cullaloe Reservoir, near Aberdour, Fifeshire, and are now published with the permission of the Admiralty. A form of directional hydrophone has already been described by Sir William Bragg. It consists of a metal diaphragm, A, about four inches in diameter, mounted in a heavy ring, B, and open to the water on both sides ( vide Chart 9). In the centre of the diaphragm is a small metal box, C, carrying a carbon granule microphone of the button type. The microphone is connected into an ordinary telephone circuit. If the instrument is rotated about a vertical diameter in water through which sound waves are passing the sound heard in the receivers passes through a number of maxima and minima. When the diaphragm is turned “edge-on” to the source of sound it is obvious that the pressure pulses will reach the two faces of the diaphragm symmetrically and the diaphragm will fail to vibrate. As, however, either face is turned toward the source this symmetry ceases to exist and the diaphragm is thrown into vibration, which reaches a maximum amplitude when the instrument is “broad-side” on to the source. The instrument, therefore, indicates the line of propagation of the sound, but owing to the existence of two positions of maximum or minimum its indications are ambiguous as regards the sense of direction.

Sound Propagation in Dilute Polyatomic Gases

1972 ◽  
Vol 27 (4) ◽  
pp. 583-592
Author(s):  
H. Moraal ◽  
F. Mccourt
Keyword(s):  
Pressure Range ◽  
Sound Propagation ◽  
Plane Waves ◽  
Point Of View ◽  
Perturbation Function ◽  
Sound Waves ◽  
Polyatomic Gas ◽  
Measured Pressure ◽  
Theory And Experiment ◽  
Good Agreement

Abstract Sound propagation in dilute pure gases, both monatomic and polyatomic, has been considered from the point of view of the Waldmann-Snider equation. It is shown that the commonly employed assumption that sound propagation in gases is equivalent to the propagation of plane waves is valid only in the region where collisions restore equilibrium faster than it is perturbed by the sound waves. A systematic truncation procedure for an expansion of the perturbation function in irreducible Cartesian tensors is introduced and then illustrated in solutions for three specific kinds of molecules, helium, nitrogen and rough spheres. The agreement between theory and experiment is rather good for sound absorption in the region where the ratio of the collision and sound frequencies is greater than 1.5. The agreement in the case of dispersion is good over the whole measured pressure range. One useful result obtained is to show the polyatomic gas calculations in second approximation have as good agreement with experiment as the calculations for noble gases in third approximation. This can be related to the possession by the polyatomic gas of a bulk viscosity which dominates in sound propagation.

scholarly journals Optical incoherent direction finder as a part of a fault-tolerant complex for landing onto small bodies of the Solar System

2020 ◽  
Vol 1615 ◽  
pp. 012016
Author(s):  
A A Lobanov ◽  
A N Alpatov ◽  
G A Mozharov ◽  
I P Torshina ◽  
V I Troitsky
Keyword(s):  
Solar System ◽  
Fault Tolerant ◽  
Small Bodies ◽  
Direction Finder

Used in Acoustic Projects Calculation of Reflection Coefficient for End Opening of Channel without Flange

2017 ◽  
Vol 6 (3) ◽  
pp. 34-41
Author(s):  
Владимир Тупов ◽  
Vladimir Tupov ◽  
А. Миронова ◽  
A. Mironova
Keyword(s):  
Reflection Coefficient ◽  
Error Analysis ◽  
Plane Waves ◽  
Computational Error ◽  
Sound Waves ◽  
Computer Approach ◽  
Coefficient Of Reflection ◽  
Plane Sound ◽  
Opening Channel

The computational error analysis for coefficient of reflection of plane sound waves at the end of opening channel without flange performed by means of formulas commonly used in practice has demonstrated their unacceptability for accurate acoustic calculations, and limitations of the Helmholtz numbers’ range, where these formulas are applicable. In this work have been proposed calculated dependences, convenient for practical usage and enabling more accurately calculate by computer approach the considered quantity’s values in a whole range of existence of the plane waves in the channel.

Interaction of sound waves. Part I: Basic equations and plane waves

1987 ◽  
Vol 82 (4) ◽  
pp. 1425-1428 ◽  
Author(s):  
Jacqueline Naze Tjo/tta ◽  
Sigve Tjo/tta
Keyword(s):  
Plane Waves ◽  
Sound Waves ◽  
Basic Equations

BEHAVIOR OF SOUND WAVES IN SHEPHERD FLUTE ON THE BASIS OF QUANTUM THEORY OF INDIVIDUAL PHONONS

2010 ◽  
Vol 24 (17) ◽  
pp. 3439-3452
Author(s):  
SONJA KRSTIĆ ◽  
VJEKOSLAV SAJFERT ◽  
BRATISLAV TOŠIĆ
Keyword(s):  
Quantum Theory ◽  
Hyperbolic Equation ◽  
Plane Waves ◽  
Sound Waves ◽  
High Frequencies ◽  
Schrödinger’S Equation ◽  
Schrödinger's Equation ◽  
Theory And Experiment ◽  
Good Agreement

Using the linearized Hamiltonian of individual phonon, it was shown that Schrödinger's equation of individual phonon is by form identical with classical hyperbolic equation. It was also shown that damper in shepherd's flute is reflexive for high frequencies and transparent for low ones. This result was experimentally tested by authors and good agreement of theory and experiment was found. The propagation of sound in parallelopipedal and cylindrical shepherd's flute was investigated. It turned out that parallelopipedal sound propagates in z-direction, only, while in cylindrical one besides plane waves in z-direction the damped waves in x, y plane appear.

scholarly journals On the propagation of waves through a stratified medium, with special reference to the question of reflection

1912 ◽  
Vol 86 (586) ◽  
pp. 207-226 ◽  
Keyword(s):  
Special Reference ◽  
Finite Thickness ◽  
Plane Waves ◽  
Stratified Medium ◽  
Negative Wave ◽  
Positive Direction ◽  
Negative Direction ◽  
Principal Problem ◽  
Propagation Of Waves ◽  
The Waves

The medium is supposed to be such that its properties are everywhere a function of but one co-ordinate x , being of one uniform quality where x is less than a certain value x 1 , and of another uniform quality (in general, different from the first) where x exceeds a greater value x m -1; and the principal problem is the investigation of the reflection which in general ensues when plane waves in the first medium are incident upon the strati-fications. For the present we suppose the quality to be uniform through strata of finite thickness, the first transition occurring when x = x 1 , the second at x = x 2 , and the last at x = x m -1. The expressions for the waves in the various media in order may be taken to be ϕ 1 = A 1 e i [ ct + by - a 1 ( x - x 1 )] + B 1 e i [ ct + by + a 1 ( x - x 1 )] , ϕ 2 = A 2 e i [ ct + by - a 2 ( x - x 1 )] + B 2 e i [ ct + by + a 2 ( x - x 1 )] , ϕ 3 = A 3 e i [ ct + by - a 3 ( x - x 2 )] + B 3 e i [ ct + by + a 3 ( x - x 2 )] , and so on, the A's and B's denoting arbitrary constants. The first terms represent the waves travelling in the positive direction, the second those travelling in the negative direction; and our principal aim is the determina­tion of the ratio B 1 /A 1 imposed by the conditions of the problem, including the requirement that in the final medium there shall be no negative wave.

scholarly journals Measurement of absorbing power of materials by the stationary wave method

1930 ◽  
Vol 127 (804) ◽  
pp. 89-110 ◽  
Keyword(s):  
Plane Waves ◽  
Stationary Wave ◽  
Small Samples ◽  
Wave System ◽  
Pressure Amplitude ◽  
Wave Method ◽  
Sound Waves ◽  
Reflected Waves ◽  
Velocity Amplitude ◽  
The Difference

The stationary wave method of determining the absorption coefficient of a material employs plane waves of sound at perpendicular incidence. It requires the use of only small samples of material and provides a rapid and convenient means of obtaining useful information. The principle of the method has been previously described, so that a brief outline is sufficient. A long pipe is provided with a source of sound at one end and is closed at the other by the test specimen. Sound waves from the source travel down the pipe and are reflected by the specimen to an extent depending on its absorbing power. The superposition of the incident and reflected waves gives rise to a stationary wave system, and the pressure amplitude varies continuously along the pipe, going through a series of maximum and minimum values. The same description applies to the velocity amplitude, with the difference that the pressure maxima coincide in position with the velocity minima and vice versa .

A new approach to problems of shock dynamics Part I Two-dimensional problems

1957 ◽  
Vol 2 (2) ◽  
pp. 145-171 ◽  
Author(s):  
G. B. Whitham
Keyword(s):  
Wave Propagation ◽  
Mach Number ◽  
Mach Reflection ◽  
Linear Equations ◽  
Plane Waves ◽  
Propagation Speed ◽  
Approximate Theory ◽  
Two Dimensional ◽  
Sound Waves ◽  
Mathematical Techniques

In this paper, two-dimensional problems of the diffraction and stability of shock waves are investigated using an approximate theory in which disturbances to the flow are treated as a wave propagation on the shocks. These waves carry changes in the slope and the Mach number of the shock. The equations governing the wave propagation are analogous in every way to the non-linear equations for plane waves in gas dynamics, and their solutions can be deduced by the same mathematical techniques. Since the propagation speed of the waves is found to be an increasing function of Mach number, waves carrying an increase in Mach number will eventually break and form what we may call a ‘shock’, corresponding to the breaking of a compression wave into a shock in the ordinary plane wave case. Such a ‘shock’ moving on the shock is called ashock-shock.The shock-shock is a discontinuity in Mach number and shock slope, and it must be fitted in to satisfy the appropriate relations between these are interpreted as the trace of cylindrical sound waves in the flow behind the shock. In particular a shock-shock is the trace of a genuine shock in the flow behind, and thus corresponds to Mach reflection.The general theory of the wave propagation is set out in § 2. The subsequent sections contain applications of the theory to specific problems, including the motion of a shock along a curved wall, diffraction by a wedge, stability of plane shocks and the instability of a converging cylindrical shock.

scholarly journals Функциональные возможности электромагнитно-акустических преобразований в токовом режиме в металлическом расплаве

2021 ◽  
Vol 57 (6) ◽  
pp. 60-71
Author(s):  
В. Н. Цуркин ◽  
◽  
А. В. Иванов ◽  
Keyword(s):  
Acoustic Field ◽  
Discharge Current ◽  
Source Parameters ◽  
Good Reason ◽  
Skin Layer ◽  
Magnetic Pressure ◽  
Sound Waves ◽  
Entire Volume ◽  
Frequency Spectra ◽  
Acoustic Disturbances

The paper deals with a symmetric problem on the base of physically substantiated estimates of the processes of electromagnetic-acoustic transformations (EMAT) of energy during the flow of an electric current through a melt, the key parameters of the open problem of the system "Power source parameters – Parameters of the magnetic field and magnetic pressure of the skin layer – Parameters of acoustic disturbances". It was shown that the key parameter when formulating the EMAT problem in technological applications is the geometry of the container with the object of processing and the material of the form. And when solving the problem, they are the parameter of the skin layer and the time dependence of the discharge current. It was established that a part of energy during the formation of the magnetic pressure in the skin layer from the amount of the energy stored in the capacitor bank of the pulse current generator is on the order of 10-4–10-2. The value of this part depends on the period of the discharge current and is proportional to the T1/2. When acoustic disturbances propagate in a melt, the main share of energy losses is determined by the difference in the acoustic stiffness of the melt and the shape of materials. The frequency spectra of the pressure of sound waves at the parameters selected for the analysis can cover the range of up to hundreds kHz, which is a good reason for the realization of resonance effects and the active formation of dissipative structures. Attention is focused on the fact that EMAT effects are manifested in the melt not only under the influence of an acoustic field, but also under that of an electromagnetic one in the skin layer. They are separated in time, but the acoustic field can occupy the entire volume of the melt and its effect is longer in time.

scholarly journals Development and Utilization of a Modified Resonator Tube Apparatus for Sound Wave Experiments

2013 ◽  
Vol 13 (1) ◽  
Author(s):  
Alwielland Q. Bello
Keyword(s):  
Speed Of Sound ◽  
Physical Phenomenon ◽  
Normal Modes ◽  
Maximum Amplitude ◽  
Acoustic Resonance ◽  
Resonance Phenomenon ◽  
Harmonic Number ◽  
Sound Waves ◽  
Minimum Amplitude ◽  
Open Pipe

Acoustic resonance is a physical phenomenon in which in-phase sound wavescombine together to produce maximum amplitude; on the other hand, out-of-phasesound waves cancel each other to produce minimum amplitude. The purpose of thisstudy is to investigate and demonstrate this phenomenon with the use of a reliabledevice. This study requires a modified resonator tube apparatus to be developed andfabricated from locally-available materials for the purpose of demonstrating resonanceand normal modes of sound waves. Air column length versus harmonic number (Lvs n) and frequency versus harmonic number (f vs n) experiments were performedtogether with open-pipe and stopped-pipe procedures. For L vs n experiments,deduced value of speed of sound is 337.79±0.94 m/s at 760 Hz for open-pipe takenat 29°C; and 357.72±9.34 m/s at 412 Hz for stopped-pipe taken at 25°C. For f vsn experiments, deduced value of speed of sound is 337.09±5.98 m/s at 2.30 m foropen-pipe taken at 25°C; and 345.92±5.55 m/s at 1.60 m for stopped-pipe takenat 30°C. Results had shown that the modified resonator tube apparatus is accurateand precise within 5% margin of error. Therefore, the apparatus is a reliable devicein demonstrating acoustic resonance phenomenon in the physics classroom setting.Keywords: Physics, Sound Waves, Resonance, Normal Modes, ExperimentalMethod, Philippines

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