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Tytuł:
Modeling the propagation of ultrasonic guided waves in a composite plate by a spectral approximation method
Autorzy:
Zitouni, Ismaine
Rhimini, Hassan
Chouaf, Abdelkerim
Powiązania:
https://bibliotekanauki.pl/articles/38896621.pdf
Data publikacji:
2023
Wydawca:
Instytut Podstawowych Problemów Techniki PAN
Tematy:
guided waves
spectral method
dispersion curves
graphite epoxy composite
acoustic power
normalized displacement.
Opis:
Graphite-epoxy composites have been able to meet the multiple requirements of the space industry. However, the radiation from the spatial environment and non-perfect adhesion between the fibers and the matrix can lead to the appearance of imperfections. To handle this, we use non-destructive testing by ultrasonic guided waves known for its high accuracy in detecting defects. In this article, we study the propagation of ultrasonic guided waves in a graphite-epoxy composite plate by the spectral method. First, the mathematical formalism is explained for modeling guided waves in the composite material. Next, we plot the dispersion curves of the composite plate in different orientations of the fibers with a MATLAB program and the results are compared with those of the DISPERSE software. These give us information on the modes that propagate in the structure. We elaborate and explain a technique based on displacement symmetry to distinguish between the different modes. A discussion based on time-saving and accuracy is established to show the advantages of the method. The second part of our paper consists in giving a physical meaning to the spectral displacements normalized in amplitude. We propose to normalize the spectral eigenvectors by the acoustic power. We plot the displacement and stress profiles of the guided modes and we compare our results to the analytical ones. Perfect correspondence is found, indicating the accuracy of the approach developed. In addition, a study of the vibrational state in the composite plate is established for Lamb and horizontal shear modes at a specific frequency.
Źródło:
Engineering Transactions; 2023, 71, 2; 213-227
0867-888X
Pojawia się w:
Engineering Transactions
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lokalizacja źródeł fal radiowych na podstawie sygnałów odbieranych przez ruchomy odbiornik pomiarowy
Location of radio waves sources on the basis of the received signals by mobile measurement receiver
Autorzy:
Ziółkowski, C.
Rafa, J.
Kelner, J. M.
Powiązania:
https://bibliotekanauki.pl/articles/208542.pdf
Data publikacji:
2006
Wydawca:
Wojskowa Akademia Techniczna im. Jarosława Dąbrowskiego
Tematy:
radiokomunikacja ruchoma
efekt Dopplera
lokalizacja źródeł fal radiowych
mobile communications
Doppler effect
location of radio waves sources
Opis:
W artykule przedstawiono oryginalną metodykę wyznaczania współrzędnych położenia źródeł promieniowania fal elektromagnetycznych, wykorzystującą pomiar częstotliwości chwilowej sygnału odbieranego przez poruszający się odbiornik. Podstawę opracowanej metodyki stanowi zależność analityczna opisująca wartość dopplerowskiego przesunięcia częstotliwości jako funkcja parametrów ruchu, parametrów generowanego sygnału oraz współrzędnych uwarunkowanych wzajemnym położeniem źródła i odbiornika sygnału. Przedstawiona analiza umożliwia ocenę wpływu różnych parametrów na zasięg prowadzenia lokalizacji źródeł fal radiowych funkcjonujących w systemach radiokomunikacyjnych i radiotechnicznych, wykorzystujących emisje sygnałów o stałej częstotliwości nośnej.
In this paper an original methodology of the position calculation of electromagnetic waves sources is introduced. This methodology applies measurement of the frequency temporary value of the received signal over moving receiver. The basis of worked out methodology is the analytic dependence, which describes Doppler's frequency shift as a function of motion parameters, generated signal and mutual position of a signal source and receiver. The described analysis ensures assessment of different parameters influence on the range of radio wave sources location. The issues presented here concern radio engineering and communication systems applying the emissions with constant carrier frequency.
Źródło:
Biuletyn Wojskowej Akademii Technicznej; 2006, 55, sp.; 67-82
1234-5865
Pojawia się w:
Biuletyn Wojskowej Akademii Technicznej
Dostawca treści:
Biblioteka Nauki
Artykuł
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
Artykuł
Tytuł:
Evaluation of geometrical influence on the hydrodynamic characteristics and power absorption of vertical axisymmetric Wave Energy Converters in irregular waves
Autorzy:
Zhang, Wanchao
Zhu, Yang
Liu, Shuxu
Wang, Jianhua
Zhang, Wentian
Powiązania:
https://bibliotekanauki.pl/articles/32920981.pdf
Data publikacji:
2023
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
vertical axisymmetric
ring-shaped stepped surface
boundary approximation
constringent
geometrical shape
Opis:
To obtain the mechanical energy of waves from arbitrary directions, the vibration absorbers of wave energy converters (WEC) are usually vertically axisymmetric. In such case, the wave-body interaction hydrodynamics is an essential research topic to obtain high-efficiency wave energy. In this paper, a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped stepped surfaces based upon the boundary approximation method (BAM) is introduced and examined. The hydrodynamic loads and parameters, such as the wave excitation forces, added mass and radiation damping of the vertical axisymmetric oscillating buoys, can then be achieved by using the new boundary discretisation method. The calculations of the wave forces and hydrodynamic coefficients show good convergence with the number of discretisation increases. Comparison between the constringent results and the results of the conventional method also verifies the feasibility of the method. Then, simulations and comparisons of the hydrodynamic forces, motions and wave power conversions of the buoys with series draught and displacement ratios in regular and irregular waves are conducted. The calculation results show that the geometrical shape has a great effect on the hydrodynamic and wave power conversion performance of the absorber. In regular waves, though the concave buoy has the lowest wave conversion efficiency, it has the largest frequency bandwidth for a given draught ratio, while in irregular waves, for a given draught ratio, the truncated cylindrical buoy has the best wave power conversion, and for a given displacement of the buoy, the concave buoy shows the best wave power conversion ability.
Źródło:
Polish Maritime Research; 2023, 2; 130-145
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of incidence angle varying from 0 rad to Π/2 rad and intensity of radio waves on the performance of a silicon solar cell
Autorzy:
Zerbo, I.
Zoungrana, M.
Saria, M.
Ouedraogo, A.
Bathiebo, D. J.
Powiązania:
https://bibliotekanauki.pl/articles/102585.pdf
Data publikacji:
2017
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
conversion efficiency
incidence angle
radio waves
shunt resistance
solar
cell
Opis:
In this work, a one dimensional approach is presented for modelling the effect of the incidence angle, varying from 0 rad to π/2 rad, and the intensity of radio waves on the performance of a polycrystalline silicon solar cell under constant multispectral illumination. By solving the continuity equation in steady state, we derived the expression of the density of excess minority carriers, the photocurrent density, the photovoltage, the electric power and their dependence on the incidence angle and the intensity of the electromagnetic field is analyzed. Using the electric power curves versus junction dynamic velocity we determined the electric power lost at the junction, the maximum electric power and we calculated the conversion efficiency for various incidence angle and intensity of the electromagnetic field. The leakage photocurrent density, deduced from the photocurrent density curves versus junction dynamic velocity, and the electric power lost at the junction allowed us to calculate the shunt resistance of the solar cell according to the incidence angle and the intensity of the electromagnetic field. The numerical data show the negative effect of radios waves on the performance of a silicon solar cell.
Źródło:
Advances in Science and Technology. Research Journal; 2017, 11, 4; 68-75
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cztery fale ewangelizacji. Refleksja o. Raniera kard. Cantalamessy na temat głoszenia kerygmatu w historii Kościoła
The four waves of evangelization. Father Raniero Cardinal Cantalamessa’s reflection on the proclamation of the kerygma in the history of the Church
Autorzy:
Zborowski, Michał
Powiązania:
https://bibliotekanauki.pl/articles/11826380.pdf
Data publikacji:
2023-03-31
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
Cantalamessa
kerygmat
ewangelizacja
keryks
kerygma
evangelization
keryx
Opis:
Ojciec kardynał Raniero Cantalamessa przedstawia cztery okresy ewangelizacji, które miały miejsce w historii Kościoła. Nazywa je „falami ewangelizacji”, wskazując, że te niezwykłe okresy ewangelizacji są przypomnieniem początków Kościoła. Ich pojawienie się wiąże się z pojawieniem się nowej grupy odbiorców niezaznajomionych z przesłaniem Ewangelii. Analiza Cantalamessy wskazuje, że faktyczną przekazywaną im treścią jest kerygmat. Odpowiedniej refleksji duszpasterskiej wymaga także wybór keryksu, który ma skutecznie docierać do odbiorców z orędziem zbawienia. Cztery „fale ewangelizacji” są zdaniem włoskiego teologa powrotem do ewangelizacji kerygmatycznej.
Father Raniero Cardinal Cantalamessa presents four periods of evangelization that have taken place in the history of the Church. He refers to them as „waves of evangelization”, indicating that these extraordinary periods of evangelization are reminiscences of the beginnings of the Church. Their appearance is related to the emergence of a new group of recipients unfamiliar with the message of the Gospel. Cantalamessa’s analysis indicates that the actual content conveyed to them is the kerygma. Appropriate pastoral reflection is also required by the choice of a keryx who is to effectively reach the recipients with the message of salvation. The four „waves of evangelization” are, according to the Italian theologian, a return to kerygmatic evangelization.
Źródło:
Annales Missiologici Posnanienses; 2022, 27; 7-24
1731-6170
Pojawia się w:
Annales Missiologici Posnanienses
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Contactless ultrasonic method for determining knitted fabrics tension
Autorzy:
Zashchepkina, N. M.
Zdorenko, V. G.
Markin, M. O.
Barilko, S. V.
Shipko, D. O.
Powiązania:
https://bibliotekanauki.pl/articles/2172163.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Komputerowej Nauki o Materiałach i Inżynierii Powierzchni w Gliwicach
Tematy:
tension of textile fabric
amplitude of ultrasonic waves
contactless control
through pores of the material
interfibre porosity
naprężenia
tkanina tekstylna
amplituda
fale ultradźwiękowe
sterowanie
matariał porowaty
porowatość włókna
Opis:
Purpose The values of the measured amplitudes of ultrasonic vibrations that have passed the controlled material have been obtained. These values were compared with the amplitude of the waves passing through the fabric sample when the initial tension was applied to it. After that, the total current value of the tension of each sample of the knitted fabric in its three zones was determined. The distribution of the total tension in different zones of the sample material was also determined. Design/methodology/approach It has been established that the amplitude of ultrasonic waves passing through different zones of the textile material can be used to determine the tension of the knitted fabric over the entire width of its fabric. Findings The possibility and expediency of determining the fabric tension on knitting equipment by using the ultrasonic contactless method has been shown. The tension of the knitted fabric in its manufacture is the main technological parameter, the value of which determines the physical, mechanical and consumer properties of the finished fabric, especially basis weight. The use of operational technological control of the tension of knitted fabrics directly during their production will improve the quality of finished products, and, accordingly, the reliability of use in personal protective equipment, in particular in body armour. It has been proposed to determine the tension of knitted fabrics in their production on knitting equipment by changing the amplitude of ultrasonic waves passing through the material under the action of tension, which also changes during the movement of the process equipment. The proposed contactless method is quite promising, since it has a number of significant advantages over the existing contact methods. In the course of the research, experimental measurements of the amplitude of ultrasonic waves have been carried out. These waves passed through samples of fabric of various materials while stretching. The samples of knitted fabrics were irradiated with an ultrasonic pulse signal with a wave frequency of 40 kHz. The samples of knitted fabrics from 58x2 Tex Kevlar threads and high molecular weight 44x3 Tex polyethylene yarns with double weave 1x1 elastic have been taken as a basis for the research. Research limitations/implications For textile fabrics, the structure of which does not allow stretching through pores under the action of tension, it is necessary to additionally adjust the contactless sensors in frequency and capacity depending on the corresponding sample. Practical implications The values of the measured amplitudes of ultrasonic vibrations that have passed the controlled material have been obtained. These values were compared with the amplitude of the waves passing through the fabric sample when the initial tension was applied to it. After that, the total current value of the tension of each sample of the knitted fabric in its three zones was determined. The distribution of the total tension in different zones of the sample material was also determined. Originality/value The dependences of the amplitude of ultrasonic waves, transmitted through the textile material in its different zones, on the value of the total tension, and on the value of the distribution of the tension of the fabric over its entire width were obtained. The deviations δP of the tension display between the determination of this parameter by the standard and ultrasonic methods are shown. The deviations δU between the amplitudes of waves passing through different zones of the controlled fabric are also determined.
Źródło:
Journal of Achievements in Materials and Manufacturing Engineering; 2022, 112, 1; 13--24
1734-8412
Pojawia się w:
Journal of Achievements in Materials and Manufacturing Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On the study of ion cyclotron waves in a cylindrical magnetized plasma
Autorzy:
Zaki, N. G.
Powiązania:
https://bibliotekanauki.pl/articles/146676.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electrostatic ion cyclotron (EIC) waves
cylindrical magnetized plasma
ion acoustic wave
torsional and compressional Alfvén waves
Opis:
In this work, a general dispersion relation of waves in the region of ion cyclotron frequency in the cylindrical magnetized plasma is derived. The waves are assumed to be cylindrically symmetric oscillations of small amplitude. Analytical calculations are performed to find the plasma dielectric tensor for the plasma consisting of hot electron and multi-component cold ions fluid. The special case of a three component plasma with hot electrons in a strong magnetic field may be interesting, e.g., in the context of fusion plasma containing D+, T+ and He2+. The general dispersion relation is simplified in two solutions. Firstly, E1 wave (E2 = 0) which has an electrostatic character, and secondly E2 wave (E1 = 0) which has an electromagnetic character. The dispersion relations for both waves are described and identified as the ion acoustic and electrostatic ion cyclotron (EIC) waves for E1 wave and the torsional Alfvén, i.e. ion cyclotron (IC) waves and the compressional Alfvén wave for E2 wave. These waves are studied due to their importance in the heating of plasmas.
Źródło:
Nukleonika; 2011, 56, 2; 179-184
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Manipulation of the supercontinuum energy distribution based on the positive chirp in photonic crystal fiber
Autorzy:
Yang, H.
Tong, X.
Zhao, S.
Huang, Y.
Powiązania:
https://bibliotekanauki.pl/articles/174604.pdf
Data publikacji:
2018
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chirp
dispersive waves
solitons
Opis:
The effect of initial frequency chirp is numerically investigated to obtain high-efficient supercontinuum radiation in photonic crystal fibers with two closely spaced zero-dispersion wavelengths. Our results show that the positive chirp can significantly improve the probability of energy transferred from the soliton to the dispersive wave. And with the increase of the chirp, the energy increases obviously. At the same time, the intensity of the dispersive wave is proportional to the chirp value. Especially, solitons will not appear when the chirp value exceeds 3.9. Therefore, choosing an appropriate positive chirp, we can regulate the energy of the dispersive wave and solitons in photonic crystal fibers.
Źródło:
Optica Applicata; 2018, 48, 1; 75-85
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dynamics of the FKT system with different mooring lines
Autorzy:
Wu, Jo-Ti
Chen, Jiahn-Horng
Hsin, Ching-Yeh
Chiu, Forng-Chen
Powiązania:
https://bibliotekanauki.pl/articles/258986.pdf
Data publikacji:
2019
Wydawca:
Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Tematy:
ocean current energy
floating turbine system
mooring line
system dynamics
surface waves
Opis:
To harness the endless hydrokinetic energy of the Kuroshio current, the joint research team of the National Taiwan University and the National Taiwan Ocean University has developed a floating Kuroshio turbine (FKT) system in Taiwan. In normal operation, the system floats at a certain small depth from the ocean surface to reduce the wave effects and take advantage of faster current speeds. In the present study, the effect of the mooring line on the system dynamics is investigated computationally. Two different auxiliary mooring line designs and, for each design, three different common mooring lines (polyester ropes of neutral buoyancy, iron chains, and 6×19 wires ropes with wire core) are examined. The study makes use of several commercial and in-house packages, integrated to find various coefficients. It is found that the mooring line, the auxiliary mooring line design, and the gravity centre can have a significant effect on system fluctuations in normal operation if the combination of these factors is not properly matched.
Źródło:
Polish Maritime Research; 2019, 1; 20-29
1233-2585
Pojawia się w:
Polish Maritime Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Śmierć ćmy
Death of the Moth
Autorzy:
Woolf, Virginia
Powiązania:
https://bibliotekanauki.pl/articles/1533590.pdf
Data publikacji:
2013-01-01
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
experimental prose
The Waves
To the Lighthouse
Jacob’s Room.
Opis:
The image of moths gathering around a source of light recurs in Woolf’s private writings and becomes an import motif also in her novels and essays. It is most probably the description of moths in her sister’s letter that become an initial inspiration for writing of The Waves, Woolf’s most radical experiment in novelistic form, where she strives to create a subject-less perspective. On the other hand The Death of The Moth, a 1927 essay, whose first translation into Polish comes together with the present commentary from the translator, is a crystal-clear description of the world as seen by the writer/narrator at her desk, surrounded by exuberant life but witnessing death. 
Źródło:
Poznańskie Studia Polonistyczne. Seria Literacka; 2013, 21; 179-185
1233-8680
2450-4947
Pojawia się w:
Poznańskie Studia Polonistyczne. Seria Literacka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulations of Alfv´en waves in the solar atmosphere with the PLUTO code
Autorzy:
Wołoszkiewicz, P.
Murawski, K.
Musielak, Z. E.
Mignone, A.
Powiązania:
https://bibliotekanauki.pl/articles/205850.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
MHD
Alfv´en waves
Opis:
With an adaptation of the PLUTO code, we present a 2.5-dimensional Cartesian magnetohydrodynamic model with the invariant (∂/∂z = 0) coordinate z of propagating magnetohydrodynamic- gravity waves in the solar atmosphere, permeated by curved magnetic field and constant gravity field g = −gˆy. This code implements second-order accurate Godunov-type numerical scheme and MPI for high level of parallelization. We show that the inhomogeneous grid, originally built in the code, resolves well the system dynamics, resulting from the localized pulse initially launched in the transverse component of velocity Vz. We consider two cases for background magnetic field Be = [Bex,Bey,Bez] with its transverse component: (a) Bez = 0 and (b) Bez 6= 0. In case (a), the initial pulse triggers only Alfv´en waves, described solely by Vz. These waves drive by ponderomotive forces the magnetoacoustic waves, associated with perturbations in Vx and Vy. As a result of Bez 6= 0, in the (b) case, Alfv´en waves are coupled to their magnetoacoustic counterparts and all three velocity components are perturbed. We show that in this case the PLUTO code is accurate, its order being 1.97 and the numerically induced flow is of magnitude ≈ 0.1 km s−1, i.e. by a factor of at least ≈ 103 lower than the characteristic (Alfv´en) speed of the system. The errors, associated with the selenoidal condition, are low with the max |∇ ・ B| ≈ 1.3 ・ 10−10 Tesla km−1. We conclude that the PLUTO code copes well with resolving all spatial and temporal scales that appear in this numerically challenging system.
Źródło:
Control and Cybernetics; 2014, 43, 2; 321-335
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Architektura współczesna w świetle uwarunkowań radiestezyjnych - mity a rzeczywistość
Contemporary architecture in the light of dowsing conditioning - myths and reality
Autorzy:
Wojtkun, G.
Powiązania:
https://bibliotekanauki.pl/articles/369629.pdf
Data publikacji:
2010
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
różdżkarstwo
strefy destrukcyjnego oddziaływania
fale Schumanna
dowsing
zones of the destructive influence
waves of Schuman
Opis:
W niniejszym artykule podjęta została problematyka kształtowania przestrzeni architektonicznej w odniesieniu do tak zwanej geotroniki. Autor starał się dociec w jakim aspekcie powinny być rozpatrywane przez projektantów architektury wskazania radiestetów? Czy powyższe może stanowić istotny wkład również do osiągnięć geologii i klimatologii?
This article includes issues of shaping the architectural space in the reference to socalled geotronics. The author tried to investigate in what aspect dowsers' guidelines should be taken into consideration by architects? Is it also the essential contribution to achievements of geology and climatology?
Źródło:
Przestrzeń i Forma; 2010, 14; 311-318
1895-3247
2391-7725
Pojawia się w:
Przestrzeń i Forma
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of experimental results and numerical calculations of ultrasonic waves scattering on a model of the artery
Autorzy:
Wójcik, J.
Trawiński, Z.
Powałowski, T.
Powiązania:
https://bibliotekanauki.pl/articles/331649.pdf
Data publikacji:
2008
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
ultrasonic waves
artery model
transmitted ultrasound
Opis:
The aim of this paper is to compare the results of the mathematical modeling and experimental results of the ultrasonic waves scattering in the inhomogeneous dissipative medium. The research was carried out for an artery model (a pipe made of a latex), with internal diameter of 3, 5 and 8 mm and wall thickness of 0.75, 1.25 and 2 mm. The numerical solver was created for calculation of the fields of ultrasonic beams and scattered fields under different boundary conditions, different angles and transversal displacement of ultrasonic beams with respect to the position of the arterial wall. The investigations employed the VED ultrasonic apparatus. The frequency of the transmitted ultrasound was 6.75 MHz. The good agreement between the numerical calculation and experimental results was obtained. The numerical solver is used for verified proposed methods for determining of the IMT in the artery walls.
Źródło:
Hydroacoustics; 2008, 11; 449-458
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Theoretical results and numerical study on the nonlinear reflection and transmission of plane sound waves
Autorzy:
Wojcik, J.
Gambin, B.
Litniewski, J.
Powiązania:
https://bibliotekanauki.pl/articles/332766.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
theoretical and numerical model
continuity conditions
non-linear waves
lossy media
Opis:
The comparison between theoretical and numerical solutions of the reflection/transmission problem for the acoustic plane wave normally incident on the discontinuity surface between two nonlinear lossy media was presented. Numerical calculations made under the assumption that the two media have the same impedance, allow to single out the effect of nonlinearities in the description of the reflection and transmission phenomena, so they agreed with theoretical predictions. It was shown that theoretically obtained and numerically calculated results mutually confirmed themselves.
Źródło:
Hydroacoustics; 2015, 18; 181-192
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 321

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