Wszystkie pola: The Waves - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Nonlinear Excitation of the Non-Wave Perturbations by the Magnetoacoustic Waves in the Non-Isentropic Plasma
Autorzy:: Perelomova, A.
Powiązania:: https://bibliotekanauki.pl/articles/177449.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: magnetoacoustic waves
dynamics of plasma
nonlinear acoustics
Opis:: Nonlinear excitation of slow modes by the planar magnetosonic perturbations in a plasma is discussed. Plasma is an open system due to radiation and external heating. This may stipulate enhancement of wave perturbations and hence the acoustical activity of plasma. Plasma is assumed to be a homogeneous ideal gas with infinite electrical conductivity. The straight magnetic field is orthogonal to the velocity of fluid’s elements. Nonlinear excitation of the non-wave modes (that is, the Alfvén and the entropy modes) by periodic and aperiodic planar magnetoacoustic perturbations, is discussed. The sawtooth wave and the small-magnitude harmonic wave are considered as examples of periodic in time perturbations. The conclusions concern acoustically active and thermally unstable flows as well.
Źródło:: Archives of Acoustics; 2018, 43, 1; 21-29
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: New Surface-Plasmon-Polariton-Like Acoustic Surface Waves at the Interface Between Two Semi-Infinite Media
Autorzy:: Kiełczyński, Piotr
Powiązania:: https://bibliotekanauki.pl/articles/31340115.pdf
Data publikacji:: 2022
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:: shear horizontal acoustic waves
surface plasmon polaritons
phase velocity
group velocity
Poynting vector
Opis:: This paper presents theory of new shear horizontal (SH) acoustic surface waves that propagate along the interface of two semi-infinite elastic half-spaces, one of which is a conventional elastic medium and a second one an elastic metamaterial with a negative and frequency dependent shear elastic compliance. This new surface waves have only one transverse component of mechanical displacement, which has a maximum at the interface and decays exponentially with distance from the interface. Similar features are also shown by the acoustic shear horizontal Maerfeld-Tournois surface waves propagating at the interface of two semi-infinite elastic media due to the piezoelectric effect that should occur in at least one semi-space. The proposed new shear horizontal acoustic surface waves exhibit also strong formal similarities with the electromagnetic surface waves of the surface plasmon polariton (SPP) type, propagating along a metal-dielectric planar interface. In fact, the new shear horizontal elastic surface waves possess a large number of properties that are inherent for the SPP electromagnetic surface waves, such as strong subwavelength concentration of the wave field in the proximity of the guiding interface, low phase and group velocity etc. As a result, the new shear horizontal acoustic surface waves can find applications in sensors with extremely high sensitivity, employed in measurements of various physical parameters, such as viscosity of liquids, as well as in biosensors, chemosensors, or a near field acoustic microscopy (subwavelength imaging) and miniaturized devices of microwave acoustics.
Źródło:: Archives of Acoustics; 2022, 47, 3; 363-371
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: A Numerical Study of The Heat Transfer Intensification Using High Amplitude Acoustic Waves
Autorzy:: Rulik, S.
Wróblewski, W.
Powiązania:: https://bibliotekanauki.pl/articles/177492.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: cavity noise
sound wave cooling
flow over a cavity
transient cooling
blade cooling intensification
Opis:: The current practice in the efforts aiming to improve cooling conditions is to place emphasis on the application of non-stationary flow effects, such as the unsteady jet heat transfer or the heat transfer intensification by means of a high-amplitude oscillatory motion. The research presented in this paper follows this direction. A new concept is put forward to intensify the heat transfer in the cooling channels with the use of an acoustic wave generator. The acoustic wave is generated by a properly shaped fixed cavity or group of cavities. The sound generated by the cavity is a phenomenon analysed in various publications focused on the methods of its reduction. The phenomenon is related to the feedback mechanism between the vortices flowing from the leading edge and the acoustic waves generated within the cavity. The acoustic waves are generated by the interaction between the vortices and the cavity walls. Strong instabilities can be observed within a certain range of the free flow velocities. The investigations presented in this paper are oriented towards the use of the phenomenon for the purposes of the heat transfer process intensification. The first part of the work presents the numerical model used in the analysis, as well as its validation and comparison with empirical relations. The numerical model is constructed using the commercial CFD Ansys CFX-16.0 commercial program. The next part includes determining of the relationship between the amplitude of the acoustic oscillations and the cooling conditions within the cavity. The calculations are performed for various flow conditions.
Źródło:: Archives of Acoustics; 2018, 43, 1; 31-47
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Technique for Measuring Spatial Distribution of the Surface Acoustic Wave Velocity in Metals
Autorzy:: Mokryy, O.
Tsyrulnyk, O.
Powiązania:: https://bibliotekanauki.pl/articles/177231.pdf
Data publikacji:: 2016
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: ultrasound
surface acoustic waves
acoustic wave velocity
spatial resolution
Opis:: In this paper a possibility of determining a local velocity of the surface acoustic Rayleigh waves using a transducer, with the rigidly connected emitting and receiving parts, is considered. A problem on spatial resolution of such a transducer for investigation of inhomogeneous specimens is also examined. A high spatial resolution can be obtained due to the transducer displacement by a value less than the distance between the emitting and receiving parts. It is shown that in this case it is not necessary to measure the transducer displacement with a high accuracy for precise determination of the velocity. Such an effect is obtained through measuring the velocity of surface waves in one local region of the specimen with respect to the other. The criterion for optimal spatial resolution selection during spatially inhomogeneous specimens study is also proposed. The proposed criterion use is illustrated on the example of the determination of spatial distribution of the surface acoustic velocity in a steel specimen subjected to inhomogeneous plastic deformation.
Źródło:: Archives of Acoustics; 2016, 41, 4; 741-746
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Noise Control Transmission Methods of the Combustion Engine by Means of Reduction of the Vibration
Autorzy:: Žiaran, S.
Chlebo, O.
Powiązania:: https://bibliotekanauki.pl/articles/176754.pdf
Data publikacji:: 2016
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: combustion engine
low frequency waves
transmission
health
measures
silnik spalinowy
fale niskiej częstotliwości
skrzynia biegów
zdrowie
środki
Opis:: Transmission of vibroacoustic energy from an internal combustion engine (ICE) to its surroundings largely depends on how it is mounted, on available transmission paths and on the construction of the vehicle body and/or its surrounding structures. This is especially true in low speed engines in enclosed areas which generate perceptually weak noise, but strong low-frequency waves which energy has a negative impact on human health, comfort and driving safety especially in prolonged exposure to the source. The primary aim of the article was to analyse components of the ICE unit which had a determining impact on the reduction of low-frequency waves. Thus, the structurally transmitted noise from the ICE to its surrounding structure (body of the passenger vehicle) was analysed. The results of the vibroacoustic measurements were compared to modal analysis in order to determine possible resonance sources in the vehicle body and/or for assessing the influence of the vehicles safety gear on the generated vibroacoustic energy transfer into the cabin area of the passenger vehicle. Measurements were made for a passenger vehicle at rest and operating in its most common operational speed as well as for the stationary ICE of a cogenerate unit (CGU). Measurements and FFT analysis were used for the detection of the vibroacoustic energy sound pressure level (noise) and mechanical vibration. Firstly, the low-frequency noise sources were determined and their direct effects on the human body were investigated. Finally, this paper suggests some measures which may contribute to the reduction of undesirable vibroacoustic energy in enclosed areas.
Źródło:: Archives of Acoustics; 2016, 41, 2; 277-284
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Standing Waves in One-Dimensional Resonator Containing an Ideal Isothermal Gas Affected by the Constant Mass Force
Autorzy:: Perelomova, A.
Powiązania:: https://bibliotekanauki.pl/articles/177416.pdf
Data publikacji:: 2017
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: acoustic resonator
non-uniform media
standing waves
Opis:: The study is devoted to standing acoustic waves in one-dimensional planar resonator which containing an ideal gas. A gas is affected by the constant mass force. Two types of physically justified boundary conditions are considered: zero velocity or zero excess pressure at both boundaries. The variety of nodal and antinodal points is determined. The conclusion is that the nodes of pressure and antinodes of velocity do not longer coincide, as well as antinodes of pressure and nodes of velocity. The entropy mode may contribute to the total field in a resonator. It is no longer isobaric, in contrast to the case when the external force is absent. Examples of perturbations inherent to the entropy mode in the volume of a resonator are discussed.
Źródło:: Archives of Acoustics; 2017, 42, 2; 263-271
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Dispersion of Rayleigh Waves in a Microstructural Couple Stress Substrate Loaded with Liquid Layer Under the Effects of Gravity
Autorzy:: Sharma, V.
Kumar, S.
Powiązania:: https://bibliotekanauki.pl/articles/947783.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: couple stress theory
Rayleigh waves
gravity
characteristic length
liquid loading
Opis:: Bone loss is one of the serious health issues in bedridden patients or young generation due to lack of physical activities. Mechanical forces are exerted on the bones through ground reaction forces, liquid loadings and by other contraction activities of the muscles. We are assuming an isotropic half-space with mechanical properties equivalent to that of bone exhibiting microstructures. Consistent couple stress theory introduces an additional material parameter called characteristic length which accounts for inner microstructure of the material. Dispersion relations for leaky Rayleigh waves are derived by considering a model consisting of couple stress half space under the effects of gravity and loaded with inviscid liquid layer of finite thickness or a liquid half space. Impact of the gravity, liquid loadings and microstructures of the material are investigated on propagation of leaky Rayleigh type waves. Phase velocity of leaky Rayleigh waves is studied for five different values of characteristic length parameter which are of the order of internal cell size of the considered material. Variations in phase velocity of leaky Rayleigh waves are also studied under the effect of gravity parameter and thickness of liquid loadings.
Źródło:: Archives of Acoustics; 2018, 43, 1; 11-20
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Investigation of the Acoustic Properties of Viscosity Standards
Autorzy:: Kazys, R.
Voleisis, A.
Sliteris, R.
Powiązania:: https://bibliotekanauki.pl/articles/176493.pdf
Data publikacji:: 2016
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: viscosity standard
longitudinal and shear waves
ultrasound velocity
Opis:: Longitudinal and shear ultrasonic wave velocities were measured versus temperature in the viscosity standards of Paragon S8000S, N30000S and Cannon N2700000. The measurements were performed by the through-transmission method at the frequency of 2 MHz. Ultrasonic pulses were sent via polymethyl methacrylate (PMMA) waveguides between the tips of which a small amount of the particular standard liquid was placed. The velocities of longitudinal and shear waves were determined to depend on the viscosity of the liquid and increase with the viscosity.
Źródło:: Archives of Acoustics; 2016, 41, 1; 55-58
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Estimation of the Crushed Ore Particles Density in the Pulp Flow Based on the Dynamic Effects of High-Energy Ultrasound
Autorzy:: Morkun, V.
Morkun, N.
Powiązania:: https://bibliotekanauki.pl/articles/176809.pdf
Data publikacji:: 2018
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: concentration
high-energy ultrasound
bulk-mode ultrasonic waves
particle size distribution
pulp characteristics
Opis:: The method of automatic measurement of the ore particles density in the pulp flow by measuring the amount of high-frequency volume ultrasonic oscillations attenuation, which have passed a fixed distance in the test medium under the influence of high-energy ultrasound dynamic effects is considered. The results of ultrasonic field parameters calculation and spatial simulation of high-energy ultrasound radiation pressure effect on the pulp flow, as well as the results of modeling the trajectory of ore particles displacement of three fractions in the pulp flow under the influence of high-energy ultrasound radiation pressure are presented.
Źródło:: Archives of Acoustics; 2018, 43, 1; 61-67
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Transmission of Ultrasonic Waves Via Optical Silica Glass Fiber Doped by 7.5% of TiO2 with the Use of Power Sandwich Transducer
Autorzy:: Muc, S.
Gudra, T.
Powiązania:: https://bibliotekanauki.pl/articles/177364.pdf
Data publikacji:: 2011
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: ultrasounds
transmission of acoustic wave in an optical waveguide
Opis:: The possibility of acoustic wave propagation in optical waveguides creates new prospects for simultaneous transmission of laser beams and ultrasonic waves. Combined laser-ultrasonic technology could be useful in e.g. surgical treatment. The article presents the results of experimental studies of transmission of ultrasonic wave in optical fibres, the core of which is doped by 7.5% of TiO2, using a sandwichtype transducer. It also presents amplitude characteristics of an ultrasonic signal propagated in the optical fibre. Authors studied the effect which the length of the fibre has on the achieved output signal amplitudes. They presented the relation of the output signal amplitude from a capacitive sensor to the power applied to the sandwich-type transducer. The obtained results were compared with the results produced when using an optical fibre with a core doped by 3% of GeO2, in order to select optical fibre suitable for simultaneous transmission of ultrasonic waves and laser rays.
Źródło:: Archives of Acoustics; 2011, 36, 1; 141-150
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 11.

Tytuł:: Evaluation of the Sedimentation Process in the Thickener by Using the Parameters of Longitudinal Ultrasonic Oscillations and Lamb Waves
Autorzy:: Morkun, Vladimir
Morkun, Natalia
Tron, Vitalii
Serdiuk, Oleksandra
Haponenko, Alona
Powiązania:: https://bibliotekanauki.pl/articles/31339774.pdf
Data publikacji:: 2023
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:: thickener
ultrasound
automatic control
modeling
parameter estimation
Opis:: Water is widely used in the mining industry, particularly in mineral enrichment processes. In the process of magnetic separation or flotation of crushed ore, a concentrate (an enriched product), and tailings (a product with a low content of a useful component) are obtained. One of the main tasks of enrichment processes is the efficient use of water resources. This is achieved by reclaiming and subsequent reusing water contained in ore beneficiation products by extracting it in industrial thickeners. Optimizing this process makes it possible to reduce water usage in the mining industry, reduce costs of mineral enrichment processes, and address extremely urgent environmental protection problems. To evaluate the process of sedimentation of the solid phase in the pulp within the thickener, measurements of parameters of longitudinal ultrasonic oscillations and Lamb waves that have traveled a fixed distance in the pulp and along the measuring surface in contact with it are used. The proposed approach allows for the consideration of pulp density, particle size of the solid phase in the ore material and the dynamics of changes in these parameters in the thickener at the initial stage of the sedimentation process. Based on the obtained values, adjustments can be made to the characteristics of its initial product, leading to reduced water usage and minimized loss of a useful component.
Źródło:: Archives of Acoustics; 2023, 48, 4; 539-548
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 12.

Tytuł:: Numerical and Experimental Analysis of the Response of a SAW Structure with WO₃ Layers on Action of Carbon Monoxide
Autorzy:: Hejczyk, T.
Urbańczyk, M.
Pustelny, T.
Jakubik, W.
Powiązania:: https://bibliotekanauki.pl/articles/176885.pdf
Data publikacji:: 2015
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: gas sensor
carbon monoxide (CO)
piezoelectric substrate
numerical modeling
surface acoustic waves
acoustoelectric effects
Ingebrigtsen's formula
Opis:: The paper presents the results of an analysis of gaseous sensors based on a surface acoustic wave (SAW) by means of the equivalent model theory. The applied theory analyzes the response of the SAW sensor in the steady state affected by carbon monoxide (CO) in air. A thin layer of WO₃ has been used as a sensor layer. The acoustical replacing impedance of the sensor layer was used, which takes into account the profile of the concentration of gas molecules in the layer. Thanks to implementing the Ingebrigtsen equation, the authors determined analytical expressions for the relative changes of the velocity of the surface acoustic wave in the steady state. The results of the analysis have shown that there is an optimum thickness of the layer of CO sensor at which the acoustoelectric effect (manifested here as a change in the acoustic wave velocity) is at its highest. The theoretical results were verified and confirmed experimentally.
Źródło:: Archives of Acoustics; 2015, 40, 1; 19-24
0137-5075
Pojawia się w:: Archives of Acoustics
Dostawca treści:: Biblioteka Nauki

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