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    Wyświetlanie 1-13 z 13
    Tytuł:
    Effect of geometry and impedance variation on the acoustic performance of a porous material lined duct
    Autorzy:
    Masmoudi, A.
    Makni, A.
    Taktak, M.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/281635.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
    Tematy:
    cylindrical duct
    discontinuity effect
    transmission
    reflection
    acoustic attenuation
    Opis:
    In this paper, the effect of geometry and impedance on the acoustic behavior of wall and lined cylindrical ducts is investigated using a numerical model which enables one to compute the reflection and the transmission coefficients of such ducts using the multimodal scattering matrix. From this matrix, the acoustic power attenuation is deduced. By using these tools, the effect of duct diameter increase and duct diameter decrease of the wall or lined duct section is studied. The numerical results are obtained for two configurations of wall and lined ducts. Numerical coefficients of transmission and reflection as well as the acoustic power attenuation show the relative influence of each type of variation.
    Źródło:
    Journal of Theoretical and Applied Mechanics; 2017, 55, 2; 679-694
    1429-2955
    Pojawia się w:
    Journal of Theoretical and Applied Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Liner Characteristics on the Acoustic Performance of Duct Systems
    Autorzy:
    Othmani, C.
    Hentati, T.
    Taktak, M.
    Elnady, T.
    Fakhfakh, T.
    Haddar, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/176887.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    porous material
    perforated plate
    duct system
    scattering matrix
    acoustic attenuation
    Opis:
    Porous materials are used in many vibro-acoustic applications. Different models describe their performance according to material’s intrinsic characteristics. In this paper, an evaluation of the effect of the porous and geometrical parameters of a liner on the acoustic power attenuation of an axisymmetric lined duct was performed using multimodal scattering matrix. The studied liner is composed by a porous material covered by a perforated plate. Empirical and phenomenal models are used to calculate the acoustic impedance of the studied liner. The later is used as an input to evaluate the duct attenuation. By varying the values of each parameter, its influence is observed, discussed and deduced.
    Źródło:
    Archives of Acoustics; 2015, 40, 1; 117-127
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Design, Manufacture and Characterization of an Acoustic Barrier Made of Multi-Phenomena Cylindrical Scatterers Arranged in a Fractal-Based Geometry
    Autorzy:
    Casteneira-Ibanez, S.
    Rubio, C.
    Romero-Garcia, V.
    Sanchez-Perez, J. V.
    Garcia-Raffi, L. M.
    Powiązania:
    https://bibliotekanauki.pl/articles/176662.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    acoustic arrays
    acoustic attenuation
    acoustic wave absorption
    acoustic wave scattering
    phononic crystals
    acoustic barrier
    physical effect of sound
    Opis:
    In this work we present the design and the manufacturing processes, as well as the acoustics standard- ization tests, of an acoustic barrier formed by a set of multi-phenomena cylindrical scatterers. Periodic arrangements of acoustic scatterers embedded in a fluid medium with different physical properties are usually called Sonic Crystals. The multiple scattering of waves inside these structures leads to attenuation bands related to the periodicity of the structure by means of Bragg scattering. In order to design the acoustic barrier, two strategies have been used: First, the arrangement of scatterers is based on fractal geometries to maximize the Bragg scattering; second, multi-phenomena scatterers with several noise con- trol mechanisms, as resonances or absorption, are designed and used to construct the periodic array. The acoustic barrier reported in this work provides a high technological solution in the field of noise control.
    Źródło:
    Archives of Acoustics; 2012, 37, 4; 455-462
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of Physical Parameters of a Porous Material Located in a Duct by Inverse Methods
    Autorzy:
    Kani, Marwa
    Makni, Amine
    Taktak, Mohamed
    Chaabane, Mabrouk
    Haddar, Mohamed
    Powiązania:
    https://bibliotekanauki.pl/articles/2141708.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    porous materials
    inverse methods
    scattering matrix
    acoustic power attenuation
    Opis:
    Lined ducts with porous materials are found in many industrial applications. To understand and simulate the acoustic behaviour of these kinds of materials, their intrinsic physical parameters must be identified. Recent studies have shown the reliability of the inverse approach for the determination of these parameters. Therefore, in the present paper, two inverse techniques are proposed: the first is the multilevel identification method based on the simplex optimisation algorithm and the second one is based on the genetic algorithm. These methods are used of the physical parameters of a simulated case of a porous material located in a duct by the computation of its acoustic transfer, scattering, and power attenuation. The results obtained by these methods are compared and discussed to choose the more efficient one.
    Źródło:
    Archives of Acoustics; 2021, 46, 4; 657-665
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation on the Effects of Acoustic Liner Variation and Geometry Discontinuities on the Acoustic Performance of Lined Ducts
    Autorzy:
    Dhief, Raja
    Makni, Amine
    Taktak, Mohamed
    Chaabane, Mabrouk
    Haddar, Mohamed
    Powiązania:
    https://bibliotekanauki.pl/articles/177513.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    absorbent systems effect
    discontinuities effect
    scattering matrix
    acoustic power attenuation
    Opis:
    Noise reduction inside waveguide systems has gained momentum owing to a great interest in it. To attenuate the sound in a broad frequency range, this study aims to compare the effects of two acoustic liners, a perforated plate backed by an air cavity (PP-Air cavity), or by a porous material (PP-PM), on the acoustic behaviour of lined ducts using a numerical model to compute the multimodal scattering matrix. From this matrix, the reflection and the transmission coefficients are computed and therefore the acoustic power attenuation is deduced. Moreover, the effects of geometry of ducts with and without changes in the section are investigated. The numerical results are obtained for five configurations, including cases of narrowing and widening of a duct portion with sudden or progressive discontinuities. Accordingly, numerical coefficients of reflection and transmission as well as the acoustic power attenuation show the relative influence of acoustic liners in each type of configuration.
    Źródło:
    Archives of Acoustics; 2020, 45, 1; 49-66
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of the Acoustic Performance of Porous Materials Lined Ducts with Geometric Discontinuities
    Autorzy:
    Tounsi, Dhouha
    Taktak, Wafa
    Dhief, Raja
    Taktak, Mohamed
    Chaabane, Mabrouk
    Haddar, Mohamed
    Powiązania:
    https://bibliotekanauki.pl/articles/2141657.pdf
    Data publikacji:
    2022
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    geometric discontinuities in duct systems
    acoustic impedance
    porous materials
    perforated plate
    acoustic power attenuation
    Opis:
    Duct silencers provide effective noise reduction for heating, ventilation and air conditioning systems. These silencers can achieve an excellent sound attenuation through the attributes of their design. The reactive silencer works on the principle of high reflection of sound waves at low frequencies. On the other hand, the dissipative silencer works on the principle of sound absorption, which is very effective at high-frequencies. Combining these two kinds of silencers allowed covering the whole frequency range. In this paper, the effect of liner characteristics composed of a perforated plate backed by a porous material and geometry discontinuities on the acoustic power attenuation of lined ducts is evaluated. This objective is achieved by using a numerical model to compute the multimodal scattering matrix, thus allowing deducing the acoustic power attenuation. The numerical results are obtained for six configurations, including cases of narrowing and widening of a radius duct with sudden or progressive discontinuities. Numerical acoustic power attenuation shows the relative influence of the variation in the values of each parameter of the liner, and of each type of radius discontinuities of ducts.
    Źródło:
    Archives of Acoustics; 2022, 47, 2; 223-240
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of the Effect of Uncertainties on the Acoustic Behavior of a Porous Material Located in a Duct Element Using the Monte Carlo Method
    Autorzy:
    Hannachi, Hanen
    Trabelsi, Hassen
    Kani, Marwa
    Taktak, Mohamed
    Chaabane, Mabrouk
    Haddar, Mohamed
    Powiązania:
    https://bibliotekanauki.pl/articles/31339920.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    porous material
    physical parameters
    transmission loss
    acoustic power attenuation
    Monte Carlo
    method
    Opis:
    When studying porous materials, most acoustical and geometrical parameters can be affected by the presence of uncertainties, which can reduce the robustness of models and techniques using these parameters. Hence, there is a need to evaluate the effect of these uncertainties in the case of modeling acoustic problems. Among these evaluation methods, the Monte Carlo simulation is considered a benchmark for studying the propagation of uncertainties in theoretical models. In the present study, this method is applied to a theoretical model predicting the acoustic behavior of a porous material located in a duct element to evaluate the impact of each input error on the computation of the acoustic proprieties such as the reflection and transmission coefficients as well as the acoustic power attenuation and the transmission loss of the studied element. Two analyses are conducted; the first one leads to the evaluation of the impacts of error propagation of each acoustic parameter (resistivity, porosity, tortuosity, and viscous and thermal length) through the model using a Monte Carlo simulation. The second analysis presents the effect of propagating the uncertainties of all parameters together. After the simulation of the uncertainties, the 95% confidence intervals and the maximum and minimum errors of each parameter are computed. The obtained results showed that the resistivity and length of the porous material have a great influence on the acoustic outputs of the studied model (transmission and reflection coefficients, transmission loss, and acoustic power attenuation). At the same time, the other physical parameters have a small impact. In addition, the acoustic power attenuation is the acoustic quantity least impacted by the input uncertainties.
    Źródło:
    Archives of Acoustics; 2023, 48, 1; 81-91
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical analysis of pressure drop and acoustic attenuation performance of two helicoidal resonators arranged in parallel ducts with different rotation angles
    Autorzy:
    Łapka, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/128303.pdf
    Data publikacji:
    2016
    Wydawca:
    Politechnika Poznańska. Instytut Mechaniki Stosowanej
    Tematy:
    helicoidal resonator
    pressure drop
    acoustic attenuation
    parallel ducts
    flow distribution
    numerical analysis
    rezonator helikoidalny
    spadek ciśnienia
    tłumienność akustyczna
    rozkład przepływu
    analiza numeryczna
    Opis:
    The paper presents a numerical analysis of pressure drop and acoustic attenuation performance (transmission loss) of two identical acoustic helicoidal resonators arranged in parallel ducts with different rotation angles. The air stream is divided from one cylindrical duct of a diameter D=140mm to a two parallel cylindrical ducts of diameter d=125mm with two helicoidal resonators inside – one per one duct. The ratio of helicoidal pitch s of helicoidal resonators to a cylindrical duct diameter d equals s/d=1,976. Other geometrical relationships of helicoidal resonators, as a mandrel diameter dm to duct diameter ratio dm/d=0.024, thickness g of helicoidal profile g/d=0.0024, and the number of helicoidal turn n=0,695 for both resonators. The investigated range of rotation angles covered the three characteristic positions of helicoidal resonators gaps, when considering the air stream distribution from central large duct with diameter D. The value of normal inflow velocity v[m/s] equaled 1 for all investigated cases.
    Źródło:
    Vibrations in Physical Systems; 2016, 27; 237-244
    0860-6897
    Pojawia się w:
    Vibrations in Physical Systems
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determination of seismic wave attenuation based on acoustic full waveforms
    Autorzy:
    Święch, E.
    Wandycz, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/89003.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Wrocławska. Wydział Geoinżynierii, Górnictwa i Geologii. Instytut Górnictwa
    Tematy:
    attenuation
    acoustic full waveforms
    quality factor Q
    Opis:
    The loss of elastic energy to the medium can be quantified by the quality factor Q. Acoustic full waveforms log from Winna Góra1 borehole were used to estimate P-wave quality factor. Data used in this paper were analyzed with usage of GeoWin software. Interpretation of acoustic full waveforms was performed for the one pair of waveforms. The most important part in the interpretation of data is manual picking of P wave arrival, calculation of semblance function, and picking anomalies of P wave on amplitude spectrum. Using data from interpretation of acoustic full waveforms, we calculated quality factor. Based on provided analysis it is concluded that the highest attenuation ( so the lowest Q) is observed in Rotliegend strata.
    Źródło:
    Mining Science; 2015, 22; 55-63
    2300-9586
    2353-5423
    Pojawia się w:
    Mining Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    O zvukoizolacionnych svojstvach zvukopogloscauscich materialov, ispol’zuemych v mnogoslojnych ograzdauscich konstrukciach
    On the acoustic properties of sound-absorbing materials which are used in external partitions
    Autorzy:
    Gerasimov, A.
    Nikonova, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/2065402.pdf
    Data publikacji:
    2015
    Wydawca:
    Politechnika Częstochowska
    Tematy:
    izolacja akustyczna
    współczynnik tłumienia
    przegrody zewnętrzne
    acoustic insulation
    acoustic impedance
    attenuation factor
    Laplace operator
    wave parameters
    Opis:
    V stat’e rassmatrivaetsa svojstva izolacii vozdusnogo zvuka ograzdauscich konstrukcij s ucetom volnovych, fiziko-mechaniceskich i strukturnych parametrov materiala zapolnenia vozdusnogo prostranstva mezdu naruznymi sloami iz poristo-voloknistych materialov i mineral’nogo volokna ISOVER.
    The article considers the insulation properties of air sound enclosure structures subject to wave, physico-mechanical and structural parameters of the material filling the air space between the outer layers of porous fibrous material and the mineral wool ISOVER.
    Źródło:
    Budownictwo o Zoptymalizowanym Potencjale Energetycznym; 2015, 2 (16); 30--38
    2299-8535
    2544-963X
    Pojawia się w:
    Budownictwo o Zoptymalizowanym Potencjale Energetycznym
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Identification of Miocene gas deposits from seismic data in the southeastern part of the Carpathian Foredeep
    Autorzy:
    Pietsch, K.
    Jarzyna, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/2059893.pdf
    Data publikacji:
    2002
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Carpathian Foredeep
    seismics
    seismostratigraphy
    velocity model
    acoustic full wavetrain
    attenuation of seismic waves
    Opis:
    Seismic interpretations are normally made to help identify and locate structural and stratigraphic traps for oil. We focus on problems in interpreting seismic sections in sandy-shaly Miocene deposits which occur in the eastern part of the Polish Carpathian Foredeep. There, the structural picture yielded by the seismic section is not in good agreement with the known structure and a correct interpretation of the seismic wave field, based on seismic modelling, is needed to ensure proper location of exploratory and production wells. We show that the correct choice of petrophysical parameters in these deposits allows interpretation of the seismic image in terms of a multi-horizon gas body. A decrease in velocity, characteristic of gas-saturated beds, was not observed in velocity obtained from sonic measurements. Therefore, several versions of a seismogeological model were constructed based on the results of integrated log interpretation. A model using seismic wave velocity obtained from acoustic wave velocity and a quality factor Q, as a measure of attenuation of elastic waves, was of particular significance. In addition to the petrophysical parameters, the strata geometry necessary to construct a seismogeological model, was determined. Combining the interpreted geometry and information regarding depths of lithostratigraphic units an anticlinal structure was deduced in the gas-rich zone. A comparison of synthetic seismograms calculated using only sonic velocity and seismic velocity corrected for attenuation, with the recorded seismic traces, shows that the best agreement was obtained for a model which included the attenuation. Differences observed between the synthetic and field sections were a basis for determining local direct hydrocarbon indicators, which were then used to identify hydrocarbon deposits in the recorded seismic section.
    Źródło:
    Geological Quarterly; 2002, 46, 4; 449-462
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Active Transient Sound Radiation Control from a Smart Piezocomposite Hollow Cylinder
    Autorzy:
    Hasheminejad, S. M.
    Rabbani, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/177572.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    active structural acoustic control (ASAC) thick cylindrical shells
    exact elasto-acoustic analysis
    time-domain solution
    intelligent system
    sound field attenuation
    Opis:
    The linear 3D piezoelasticity theory along with active damping control (ADC) strategy are applied for non-stationary vibroacoustic response suppression of a doubly fluid-loaded functionally graded piezolaminated (FGPM) composite hollow cylinder of infinite length under general time-varying excitations. The control gain parameters are identified and tuned using Genetic Algorithm (GA) with a multi-objective performance index that constrains the key elasto-acoustic system parameters and control voltage. The uncontrolled and controlled time response histories due to a pair of equal and opposite impulsive external point loads are calculated by means of Durbin’s numerical inverse Laplace transform algorithm. Numerical simulations demonstrate the superior (good) performance of the GA-optimized distributed active damping control system in effective attenuation of sound pressure transients radiated into the internal (external) acoustic space for two basic control configurations. Also, some interesting features of the transient fluid-structure interaction control problem are illustrated via proper 2D time domain images and animations of the 3D sound field. Limiting cases are considered and accuracy of the formulation is established with the aid of a commercial finite element package as well as comparisons with the current literature.
    Źródło:
    Archives of Acoustics; 2015, 40, 3; 359-381
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analiza tłumienia prędkości fali podłużnej w elemencie żelbetowym z zarysowaniem
    Analysis of damping the speed of longitudinal wave in a reinforced concrete element with a scratch
    Autorzy:
    TEODORCZYK, Michał
    Powiązania:
    https://bibliotekanauki.pl/articles/455619.pdf
    Data publikacji:
    2012
    Wydawca:
    Uniwersytet Rzeszowski
    Tematy:
    fala sprężysta
    prędkość
    tłumienie
    emisja akustyczna
    obciążenie
    zarysowanie
    konstrukcja żelbetowa
    diagnostyka
    elastic wave
    velocity
    attenuation
    acoustic emission
    load
    scratch
    reinforced concrete structure
    diagnosis
    Opis:
    W pracy przedstawiono wpływ zarysowania na prędkość podłużnych fal akustycznych w elemencie żelbetowym pod obciążeniem. Badania przeprowadzono na belce o wymiarach 120 × 300 × 6300 mm wykonanej w zakładzie prefabrykacji. Pokazano, iż powstawaniu rys towarzyszy spadek prędkości propagacji fal nawet o ponad 50%. Analiza prędkości rozchodzenia się podłużnych fal akustycznych w elementach pod obciążeniem jest perspektywą opracowania metody nieniszczącej oceny stanu technicznego konstrukcji betonowych. Efektem pomiaru jest spadek prędkości fal do pewnego poziomu degradacji materiału.
    This paper presents effect of cracks formation on the velocity of longitudinal acoustic waves in reinforced concrete element under load. Experiments were carried out on 120 × 300 × 6300 mm prefabricated beams. It was found, that formation of cracks causes attenuation of elastic wave (acoustic) velocity of over 50%. Hence, analysis of the elastic wave velocity can be used for structures diagnosis. Research will be carried out to develop non-destructive method for evaluation of technical state of reinforced concrete structures, which is based on the of longitudinal wave velocity.
    Źródło:
    Edukacja-Technika-Informatyka; 2012, 3, 1; 303-308
    2080-9069
    Pojawia się w:
    Edukacja-Technika-Informatyka
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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