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1

Deagglomeration and Coagulation of Particles in Liquid Metal Under Ultrasonic Treatment

Kudryashova Olga, Vorozhtsov Alexander, Danilov Pavel

Archives of Acoustics

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2019

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Vol. 44, No. 3

543--549

EN

Ultrasonic processing in the cavitation mode is used to produce the composite materials based on the metal matrix and reinforcing particles of micro- and nano-sizes. In such a case, the deagglomeration of aggregates and the uniform distribution of particles are the expected effects. Although the particles can not only fragment in the acoustic field, they also can coagulate, coarsen and precipitate. In this paper, a theoretical study of processes of deagglomeration and coagulation of particles in the liquid metal under ultrasonic treatment is made. The influence of various parameters of ultrasound and dispersion medium on the dynamics of particles in the acoustic field is considered on the basis of the proposed mathematical model. The criterion of leading process (coagulation or deagglomeration) has been proposed. The calculated results are compared with the experimental ones known from the scientific literature.

2

The Acoustic Field Distribution Inside the Ultrasonic Ring Array

Staszewski W., Gudra T., Opieliński K. J.

Archives of Acoustics

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2018

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Vol. 43, No. 3

455--463

EN

This paper presents and analyses the results of a simulation of the acoustic field distribution in sectors of a 1024-element ring array, intended for the diagnosis of female breast tissue with the use of ultrasonic tomography. The array was tested for the possibility to equip an ultrasonic tomograph with an additional modality - conventional ultrasonic imaging with the use of individual fragments (sections) of the ring array. To determine the acoustic field for sectors of the ring array with a varying number of activated ultrasonic transducers, a combined sum of all acoustic fields created by each elementary transducer was calculated. By the use of MATLAB software, a unique algorithm was developed, for a numerical determination of the distribution of pressure of an ultrasonic wave on any surface or area of the medium generated by the concave curvilinear structure of rectangular ultrasound transducers with a geometric focus of the beam. The analysis of the obtained results of the acoustic field distribution inside the ultrasonic ring array used in tomography allows to conclude that the optimal number of transducers in a sector enabling to obtain ultrasound images using linear echographic scanning is 32 ≤ n ≤ 128, taking into account that due to an increased temporal resolution of ultrasonic imaging, this number should be as low as possible.

3

Testing the Acoustic Silencers

Pierchała M.

Archives of Acoustics

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2018

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Vol. 43, No. 2

313--321

EN

Problems associated with designing silencers are presented. Results of direct tests of silencers for cooperation with systems of axial fans, as well as results of numerical tests of a two stage acoustic silencer, are given. The numerical tests enabled determining the distribution of acoustic field inside the silencer and in the surrounding area. In those tests A sound insertion losses for different variants of installation inside the silencer, as well as for two different types of absorbing material used to fill the silencer walls, were determined. Impact of design features of silencers on effectiveness of noise reduction is described. Also, a technical sketch of a universal silencer with significant noise reduction (DipS = 39:1 dB) which can be successfully used in many ventilation systems is presented.

4

Zastosowanie radialnych funkcji bazowych do analizy pola akustycznego wnętrz pojazdów

Majkut L.

Autobusy : technika, eksploatacja, systemy transportowe

|

2016

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R. 17, nr 12

1183--1187

PL

W artykule opisano możliwości zastosowania jednej z tzw. metod bezsiatkowych do analizy pola akustycznego wnętrza pojazdu. Do analizy wybrano metodę kolokacyjną z bazą globalnych funkcji radialnych. W kolejnych punktach pracy opisano wykorzystywaną metodę analizy i jej zastosowanie do wyznaczenia częstości drgań własnych i charakterystyk amplitudowo-częstotliwościowych wnętrza przykładowego pojazdu. Charakterystyki wyznaczono w dwóch układach źródła: jedno źródło zlokalizowane na środku przedniej części pojazdu (układ siso) i dwa źródła umieszczone po bokach pojazdu (układ miso). Wartości częstości własnych porównano z analizą Metodą Elementów Skończonych.

EN

The work concerns the in acoustics of an vehicle interior with the Radial Based Functions. The collocation method was used for determination eigenvalues and frequency response functions of the car interior. All eigenvalues were compared with Finite Element Analysis results. All results indicate that using of multiquadric (MQ) RBF provide a results with very high accuracy in comparison to numerical results in acoustic analysis of 3D close domain.

5

Modeling of acoustic field for a parametric focusing source using the spheroidal beam equation

Yu L., Li J., Shi C.

Polish Maritime Research

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2015

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S 1

43--47

EN

A theoretical model of acoustic field for a parametric focusing source on concave spherical surface is proposed. In this model, the source boundary conditions of the Spheroidal Beam Equation (SBE) for difference frequency wave excitation were studied. Propagation curves and beam patterns for difference frequency component of the acoustic field are compared with those obtained for Khokhlov-Zabolotskaya-Kuznetsov (KZK) model. The results demonstrate that the focused parametric model of SBE is good valid for a large aperture angle in the strongly focused acoustic field. It is also investigated that high directivity and good focal ability with the decreasing of downshift ratio and the increasing of half-aperture angle for the focused parametric model of SBE.

6

The method of mapping of acoustic field, emitted by sources of sound in the environment, with implementation of the MEMS IMU unit and laser devices

Kompała J., Motyka Z., Szade A., Świder J.

Measurement Automation Monitoring

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2015

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Vol. 61, No. 3

68--71

EN

During the course of the research, a methodology of measurement of sources of noise was developed, along with measurement models and measurement sets. The latter were equipped with microphones, acoustic pressure level meters, devices determining spatial orientation of the measurement (laser rangefinder, inertial measurement unit 3D IMU) and software processing the data, obtained including final spatial mapping of the acoustic field. The system has been successfully tried in large indoor areas.

7

Wpływ oprzyrządowania pomiarowego na rozkład pola akustycznego

Olszewski R.

TTS Technika Transportu Szynowego

|

2013

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R. 20, nr 10

1117--1124, CD

PL

Artykuł dotyczy badań modelowych wpływu oprzyrządowania pomiarowego na pole akustyczne w którym się znajdują. Przedstawiono wyniki dla dwóch obiektów różniących się kształtem, które są wymieniane jako możliwe do wykorzystania w charakterze urządzenia pozwalającego przemieszczać elementy toru pomiarowego.

EN

The paper concerns a model based research of an impact of a measurement equipment on the acoustic field it is located in. The results for the two objects that differ in shape, and both are possible to use as a device allowing to move the measurement path elements, are presented.

8

Numerical modeling of transient acoustic field using finite element method

Koudela L., Jansa J., Karban P.

Poznan University of Technology Academic Journals. Electrical Engineering

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2013

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No. 73

155--160

EN

Numerical solution of acoustic wave equation in the time domain is performed. The appropriate mathematical model is described by the partial differential wave equation supplemented with appropriate boundary conditions. The goal is to obtain the time evolution of the distribution of acoustic pressure, which can serve as the basis for the solution of various subsequent problems. The paper discusses the results of the numerical analysis of a semicircular acoustic diffuser in a free field, realized by a fully adaptive higher-order finite element method implemented in our own codes Agros2D and Hermes. The results are compared with the data obtained by the commercial code Comsol Multiphysics.

9

A simple model of sound in enclosures with a low frequency harmonic excitation

Błażejewski A., Krzyżyński T.

Vibrations in Physical Systems

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2012

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Vol. 25

77--82

EN

In the paper the problem of a room with a sound source inside is investigated. The effect, an acoustic field inside is affected by two factors: the shape and the boundaries of the enclosure. In order to evaluate the acoustic field, modal analysis assumption has been applied to describe the room's pressure distribution. Thus, the sum over a set of the room's eigenfunctions and proper time components represents the values of the acoustic field. Eigenfunctions can be obtained by solving the Helmholtz equation for rigid walls. Time components can be determined applying Green’s theorem. This approach allows boundary conditions to be adjoined to time components and thereafter obtain a set of ordinary differential equations for each specified time component correlated with corresponding eigenfunction. Assuming a harmonic excitation, time components are harmonic as well. Therefore, the values of coefficients of each time component (i.e. the modal amplitudes) are required. Directly, one can evaluate the modal amplitudes by solving simple algebraic equations. As a result of this calculation, the finite set of eigenfunctions of an enclosure and modal amplitudes has been obtained. In this case of an additional assumption of high enough boundary impedance, the modal coupling can be neglected and consecutive formula reduction is possible. Under frequency limitation, the modal approach to a room's acoustic field modelling, involves much less computational effort than the alternative, for instance applying Finite Element Method (FEM) or Boundary Element Method (BEM).

10

Analiza rozkładu pola akustycznego w środowisku wybranych obiektów energetycznych

Augustyn A.

Maszyny Górnicze

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2009

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R. 27, nr 2

30-34

PL

Hałas jest czynnikiem niezwykle szkodliwym, którego konieczność ograniczania wynika z negatywnych skutków, jakie on wywołuje. Wytyczne w zakresie ograniczania ponadnormatywnej emisji hałasu zawarto w obowiązujących wymaganiach formalno- prawnych. Istotnymi źródłami przekroczeń dopuszczalnych poziomów dźwięku są obiekty energetyczne, których jedną z najbardziej charakterystycznych cech jest występujące na ich terenie pole akustyczne o cechach pola silnie dyfuzyjnego. Tak skonstruowana charakterystyka źródła utrudnia prowadzenie zarówno badań doświadczalnych, jak i badań modelowych. Niniejszy artykuł jest próbą przybliżenia aktualnie stosowanych metod identyfikacji znaczących źródeł hałasu, jak również określania rozkładu pola akustycznego. Zaproponowano alternatywną w stosunku do klasycznej metodę prowadzenia analiz rozkładu pola akustycznego obiektów energetycznych. Przeprowadzono również walidację obowiązujących metod badań, udowadniając ich niską przydatność w analizach obiektów energetycznych. Wydaje się, iż dotychczas rzadko stosowana metoda natężeniowa jest jednym ze środków pozwalających na ograniczenie znacznej części błędów pomiarowych, jak również identyfikację zakłóceń akustycznych.

EN

Noise is extremely harmful factor and the need of its reduction results from negative effects it causes. Guidelines as regards reduction of over-standard noise emission were included in formal requirements which are in force. Power objects are significant sources in exceeding of permissible noise level. Acoustic field of strongly diffusive field features, which is present in the area of power objects, is one of the most characteristic features of power objects. Characteristics of source, which is designed in such way, makes it difficult to carry out both experimental tests and model tests. The paper is an attempt of approaching currently used methods of identification of significant noise sources, as well as determination of acoustic field distribution. A method of conducting the analyses of acoustic field distribution of power objects, which is alternative to classical method, was suggested. A validation of testing methods, which are in force, was also conducted, proving their low usefulness in analyses of power objects. It seems that intensity method, which was rarely used so far, is one of means, which enable reduction of significant part of measuring errors, as well as identification of acoustic disturbances.

11

Metoda wizualizacji pola akustycznego mis dźwiękowych

Meyer A., Portalska H., Portalski M., Konieczka A., Balcerek J.

Elektronika : konstrukcje, technologie, zastosowania

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2009

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Vol. 50, nr 3

29-34

PL

W artykule przedstawiono wielomikrofonowe stanowisko pomiarowe do badania dźwięku mis dźwiękowych. Podano metodę komputerowej generacji obrazu przedstawiającego przestrzenny rozkład energii dźwięku mis oraz przykładowe obrazy tego rozkładu. Potwierdzono obserwowaną przez terapeutów zmienność w czasie i anizotropię pola akustycznego mis, a także wirowy charakter tego pola.

EN

In this paper multimicrophone measurement post to test of special sound bowls is presented. The method of digital image generations showing spatial distribution of bowls' sound energy and image of energy distribution examples are given. The influence of bowl's acoustic field on time and space both and circular character of this acoustic field are confirmed.

12

Determination of the sound power of a machine inside an industrial room by the inversion method

Piechowicz J.

Archives of Acoustics

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2009

|

Vol. 34, No. 2

169-176

EN

Utilisation of the substitute sources system consisting of monopole sound sources is one of the methods of sound sources modelling in the industry. The knowledge of the actual acoustic pressure distribution around industrial sound sources is necessary for determination of the parameters of such models. In order to satisfy requirements, the distribution of acoustic pressure amplitudes as well as the distribution of phase shift angles between acoustic signals are to be determined. The presented investigations constitute a part of the research program related to the application of inversion methods in the assessment of acoustic parameters of machines operating under industrial conditions, as well as to the comparative analysis of the hereby obtained results with the results obtainable by other methods of testing.

13

Analysis of Dome Home Hall theatre acoustic field

Gołaś A., Suder-Dębska K.

Archives of Acoustics

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2009

|

Vol. 34, No. 3

273-293

EN

The modelling of compartment in simulation software enables determination of acoustic parameters' distributions in a virtual compartment. The elementary question is how much the simulations reflect the actual state in a room. Analysing the acoustics of dome-shaped compartments, i.e. for instance various basilicas, a conclusion can be drawn that the acoustics of these objects is very good. Therefore the authors decided to analyse the influence of a dome shape on acoustic parameters of the compartment.

14

Acoustic energy distribution in space around the pipe outlet

Weyna S.

Archives of Acoustics

|

2007

|

Vol. 32, No. 2

387-397

EN

Visualization system, by serving a dual role as a provider of exploration and exposition capabilities, have became indispensable to the analysis of computational fluid dynamics (CFD) results. In the acoustical practice, up until the last two decades, the study of vectors acoustic fields and noise flow visualisation are rather seldom. But direct measurement of the flow intensity sound as the energetic fields and graphically description of the results, can explain a diffraction and scattering phenomena occur on the real noise sources and solved in practical way a lot of engineering problems. Based on the research with intensity technique and using selected visualizations methods, in the publication are demonstrate in graphical form the sound intensity effects in the space around outlet region of cylindrical pipe. The duct model have a partly square and barrel shaped cross-section. The outlet research space was scanning with intensity probe measured the x, y and z components of sound intensity vector. Direct measurement of the acoustic power flow around outlet can explain all diffraction and scattering phenomena occur in this region and the noise generated by inside flow and around outlet of duct is an environmental concern in engineering practice.

15

Essentials of assessment of acoustic efficiency of complex mechanical structures

Golec M., Golec Z., Tabaszewski M.

Vibrations in Physical Systems

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2006

|

Vol. 22

123--128

16

FEM amd BEM computing costs for acoustical problems

Bolejko R., Dobrucki A.

Archives of Acoustics

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2006

|

Vol. 31, No. 2

193-212

EN

FEM and BEM computing costs are compared for acoustical problems. The cost analysis was carried out for bounded areas of simple shapes for objects with acoustical losses (e.g. with sound absorbing materials). BEM's variational-collocative scheme (DBEM) and its variational scheme (IBEM) were considered. Computing costs were calculated, taking into account main matrix composition costs and main system of equations solution costs. The costs were calculated for the type of adopted discrete elements and the order of quadrature used. Analytical relations for calculating main matrix composition costs for BEM have been derived. The analysis shows that FEM computing costs can be lower than BEM computing costs. Moreover, BEM computing costs are strongly dependent on the order of the quadrature used. The presented results provide a basis for the choice of the most cost-effective method depending on the size of an acoustical problem.

17

Numerické modelování šířeni hluku

Biskup M.

Zeszyty Naukowe Katedry Mechaniki Stosowanej / Politechnika Śląska

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2002

|

z. 19

13-16

EN

This paper is concerned in modeling of noise propagation of a small end-fixed plate. The excitation was harmonic in range of audibility region. The modeling of noise propagation is made in MATLAB r.6. The noise propagation is calculated in ANSYS 5.7 because of comparing. The analysis of size of acoustic field in effect on a sound pressure level in case of model without boundary elements in the border of acoustic field is made.

18

Ocena pola akustycznego wokół dróg w warunkach polskich

Lebiedowska B.

Izolacje

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2000

|

R. 5, nr 2

59-62

PL

Transport należy do głównych źródeł uciążliwości dla ludzi i środowiska naturalnego poprzez emisję spalin i hałasu. Wielkość zagrożonego terenu tymi uciążliwościami szacuje się na około 17% powierzchni naszego kraju (przy 21% dla wszystkich źródeł hałasu). Zagrożeniami, wynikającymi z nadmiernej emisji gazów oraz ołowiu, związanymi z transportem obarcza się około 30% emisji pochodzących ze wszystkich źródeł.