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    Wyświetlanie 1-10 z 10
    Tytuł:
    Performance Evaluation of T-Shaped Noise Barriers Covered with Oblique Diffusers Using Boundary Element Method
    Autorzy:
    Monazzam, Mohammad Reza
    Abbasi, Milad
    Yazdanirad, Saeid
    Powiązania:
    https://bibliotekanauki.pl/articles/177090.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    noise barrier
    oblique diffuser
    T-shaped
    boundary element method
    Opis:
    One of the most effective designs to control the road traffic noise is the T-shaped barrier. The aim of this study was to examine the performance of T-shape noise barriers covered with oblique diffusers Rusing boundary element method. A 2D simulation technique based on the boundary element method (BEM) was used to compute the insertion loss at the center frequency of each one-third octave band. In designer barriers, the top surface of the T-shaped noise barriers was covered with oblique diffusers. The width and height of the barrier stem and the width of its cap were 0.3, 2.7, and 1 m, respectively. Angles of the oblique diffusers were 15, 30, and 45 degrees. The oblique diffusers were placed on the top surface with two designs including same oblique diffusers (SOD) and quadratic residue oblique diffusers (QROD). Barriers considered were made of concrete, an acoustically rigid material. The barrier with characteristics of QROD, forward direction, and sequence of angles (15, 30, and 45 degrees) had the greatest value of the overall A-weighted insertion loss equal to 18.3 to 21.8 dBA at a distance of 20 m with various heights of 0 to 6 m.
    Źródło:
    Archives of Acoustics; 2019, 44, 3; 521-531
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    2D Structural Acoustic Analysis Using the FEM/FMBEM with Different Coupled Element Types
    Autorzy:
    Chen, L.
    Zhao, W.
    Liu, C.
    Chen, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/176330.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    boundary element method
    finite element method
    discontinuous boundary elements
    acoustic fluid-structure interaction
    fast multipole method
    Opis:
    A FEM-BEM coupling approach is used for acoustic fluid-structure interaction analysis. The FEM is used to model the structure and the BEM is used to model the exterior acoustic domain. The aim of this work is to improve the computational efficiency and accuracy of the conventional FEM-BEM coupling approach. The fast multipole method (FMM) is applied to accelerating the matrix-vector products in BEM. The Burton-Miller formulation is used to overcome the fictitious eigen-frequency problem when using a single Helmholtz boundary integral equation for exterior acoustic problems. The continuous higher order boundary elements and discontinuous higher order boundary elements for 2D problem are developed in this work to achieve higher accuracy in the coupling analysis. The performance for coupled element types is compared via a simple example with analytical solution, and the optimal element type is obtained. Numerical examples are presented to show the relative errors of different coupled element types.
    Źródło:
    Archives of Acoustics; 2017, 42, 1; 37-48
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Acoustic Attenuation Performance Analysis and Optimisation of Expansion Chamber Coupled Micro-perforated Cylindrical Panel Using Response Surface Method
    Autorzy:
    Alisah, Mohamad Izudin
    Ooi, Lu Ean
    Ripin, Zaidi Mohd
    Yahaya, Ahmad Fadzli
    Ho, Kelvin
    Powiązania:
    https://bibliotekanauki.pl/articles/1945638.pdf
    Data publikacji:
    2021
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    micro-perforated cylindrical panel
    transmission loss
    boundary element method
    response surface method
    Opis:
    This paper describes the boundary element method (BEM) and the experimental and optimisation studies conducted to understand the potential of expansion chamber coupled micro-perforated cylindrical panel (MPCP) in enhancing the acoustic attenuation for in-duct noise control issues. Owing to the complex structure of the MPCP and to achieve the correct prediction of acoustic attenuation, BEM is adopted on the basis of the Simcenter 3D software to compute the sound transmission loss (TL), As the MPCP is cylindrical in shape with numbers of sub-milimeter holes, additive manufacturing-based 3D printing is utilised for the model prototyping to reduce current design limitation and enable fast fabrication. The TL measurement-based two-load method is adopted for model validation. Subsequently, parametric studies of the MPCP concerning the perforation hole diameter, perforation ratio and depth of air space are carried out to investigate the acoustic performance. Optimisation via response surface method is used as it allows for evaluating the effects of multiple parameters as required in this study. The model validation result shows that the error between the BEM and the measured values is relatively small and shows good agreement. The R-square value is 0.89. The finding from the parametric studies shows that a wider peak attenuation can be achieved by reducing the perforation hole diameter, and one way to increase the TL amplitude is by increasing the air cavity depth. Finally, the optimised MPCP model is adopted to the commercial vacuum cleaner for verification. The sound pressure level of the vacuum cleaner is significantly attenuated within the objective frequency of 1.7 kHz.
    Źródło:
    Archives of Acoustics; 2021, 46, 3; 507-517
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Isogeometric Fast Multipole Boundary Element Method Based on Burton-Miller Formulation for 3D Acoustic Problems
    Autorzy:
    Chen, Leilei
    Zhao, Wenchang
    Liu, Cheng
    Chen, Haibo
    Marburg, Steffen
    Powiązania:
    https://bibliotekanauki.pl/articles/177486.pdf
    Data publikacji:
    2019
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    isogeometric analysis
    boundary element method
    Burton-Miller method
    acoustic scattering
    fast multipole method
    Opis:
    An isogeometric boundary element method is applied to simulate wave scattering problems governed by the Helmholtz equation. The NURBS (non-uniform rational B-splines) widely used in the CAD (computer aided design) field is applied to represent the geometric model and approximate physical field variables. The Burton-Miller formulation is used to overcome the fictitious frequency problem when using a single Helmholtz boundary integral equation for exterior boundary-value problems. The singular integrals existing in Burton-Miller formulation are evaluated directly and accurately using Hadamard’s finite part integration. Fast multipole method is applied to accelerate the solution of the system of equations. It is demonstrated that the isogeometric boundary element method based on NURBS performs better than the conventional approach based on Lagrange basis functions in terms of accuracy, and the use of the fast multipole method both retains the accuracy for isogeometric boundary element method and reduces the computational cost.
    Źródło:
    Archives of Acoustics; 2019, 44, 3; 475-492
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Coupled Smoothed Finite Element-Boundary Element Method for Structural-Acoustic Analysis of Shell
    Autorzy:
    Tian, W.
    Yao, L.
    Li, L.
    Powiązania:
    https://bibliotekanauki.pl/articles/177260.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    SFEM
    smoothed finite element method
    FEM
    finite element method
    BEM
    boundary element method
    structural-acoustic analysis
    Opis:
    Nowadays, the finite element method (FEM) – boundary element method (BEM) is used to predict the performance of structural-acoustic problem, i.e. the frequency response analysis, modal analysis. The accuracy of conventional FEM/BEM for structural-acoustic problems strongly depends on the size of the mesh, element quality, etc. As element size gets greater and distortion gets severer, the deviation of high frequency problem is also clear. In order to improve the accuracy of structural-acoustic problem, a smoothed finite-element/boundary-element coupling procedure (SFEM/BEM) is extended to analyze the structural-acoustic problem consisting of a shell structure interacting with the cavity in this paper, in which the SFEM and boundary element method (BEM) models are used to simulate the structure and the fluid, respectively. The governing equations of the structural-acoustic problems are established by coupling the SFEM for the structure and the BEM for the fluid. The solutions of SFEM are often found to be much more accurate than those of the FEM model. Based on its attractive features, it was decided in the present work to extend SFEM further for use in structural-acoustic analysis by coupling it with BEM, the present SFEM/BEM is implemented to predict the vehicle structure-acoustic frequency response analysis, and two numerical experiments results show that the present method can provide more accurate results compared with the standard FEM/BEM using the same mesh. It indicates that the present SFEM/BEM can be widely applied to solving many engineering noise, vibration and harshness (NVH) problems with more accurate solutions.
    Źródło:
    Archives of Acoustics; 2017, 42, 1; 49-59
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Shape Optimisation of Multi-Chamber Acoustical Plenums Using BEM, Neural Networks, and GA Method
    Autorzy:
    Chang, Y.-C.
    Cheng, H.-C.
    Chiu, M.-C.
    Chien, Y.-H.
    Powiązania:
    https://bibliotekanauki.pl/articles/177780.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    boundary element method
    plenum
    centre-opening baffle
    polynomial neural network model
    group method of data handling
    optimisation
    genetic algorithm
    Opis:
    Research on plenums partitioned with multiple baffles in the industrial field has been exhaustive. Most researchers have explored noise reduction effects based on the transfer matrix method and the boundary element method. However, maximum noise reduction of a plenum within a constrained space, which frequently occurs in engineering problems, has been neglected. Therefore, the optimum design of multi-chamber plenums becomes essential. In this paper, two kinds of multi-chamber plenums (Case I: a two-chamber plenum that is partitioned with a centre-opening baffle; Case II: a three-chamber plenum that is partitioned with two centre-opening baffles) within a fixed space are assessed. In order to speed up the assessment of optimal plenums hybridized with multiple partitioned baffles, a simplified objective function (OBJ) is established by linking the boundary element model (BEM, developed using SYSNOISE) with a polynomial neural network fit with a series of real data – input design data (baffle dimensions) and output data approximated by BEM data in advance. To assess optimal plenums, a genetic algorithm (GA) is applied. The results reveal that the maximum value of the transmission loss (TL) can be improved at the desired frequencies. Consequently, the algorithm proposed in this study can provide an efficient way to develop optimal multi-chamber plenums for industry.
    Źródło:
    Archives of Acoustics; 2016, 41, 1; 43-53
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Nonsingular Meshless Method in an Acoustic Indoor Problem
    Autorzy:
    Brański, A.
    Prędka, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/177716.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    architectural acoustics
    meshless method
    radial bases functions
    impedance boundary condition
    Opis:
    An efficiency of the nonsingular meshless method is analyzed in an acoustic indoor problem. The solution is assumed in the form of the series of radial bases functions. The Hardy’s multiquadratic functions, as the bases, are taken into account. The room acoustic field with uniform, impedance walls is considered. The representative, rectangular cross section of the room is chosen. Practical combinations of acoustic boundary conditions, expressed through absorption coefficient values, are considered. The classical formulation of the boundary problem is used. It is established any coefficient in the multiquadratic functions depend on the number of influence points, the frequency and the absorption coefficient. All approximate results are calculated in relation to the exact ones. This way, it is proved that the meshless method based on the multiquadratic functions is simple and efficient method in the description of the complicated acoustic boundary problems for the low and medium ranges of frequency.
    Źródło:
    Archives of Acoustics; 2018, 43, 1; 75-82
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Selected Aspects of Meshless Method Optimization in the Room Acoustics with Impedance Boundary Conditions
    Autorzy:
    Prędka, Edyta
    Kocan-Krawczyk, Anna
    Brański, Adam
    Powiązania:
    https://bibliotekanauki.pl/articles/1953537.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    architectural acoustics
    meshless method
    radial basis functions
    impedance boundary condition
    Opis:
    Two optimization aspects of the meshless method (MLM) based on nonsingular radial basis functions (RBFs) are considered in an acoustic indoor problem. The former is based on the minimization of the mean value of the relative error of the solution in the domain. The letter is based on the minimization of the relative error of the solution at the selected points in the domain. In both cases the optimization leads to the finding relations between physical parameters and the approximate solution parameters. The room acoustic field with uniform, impedance walls is considered. As results, the most effective Hardy’s Radial Basis Function (H-RBF) is pointed out and the numer of elements in the series solution as a function of frequency is indicated. Next, for H-RBF and fixed n, distributions of appropriate acoustic fields in the domain are compared. It is shown that both aspects of optimization improve the description of the acoustic field in the domain in a strictly defined sense.
    Źródło:
    Archives of Acoustics; 2020, 45, 4; 647-654
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of the Room Acoustic with Impedance Boundary Conditions in the Full Range of Acoustic Frequencies
    Autorzy:
    Prędka, Edyta
    Brański, Adam
    Powiązania:
    https://bibliotekanauki.pl/articles/176668.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    architectural acoustic
    meshless method
    radial bases functions
    impedance boundary condition
    Opis:
    An efficiency of the nonsingular meshless method (MLM) was analyzed in an acoustic indoor problem. The solution was assumed in the form of the series of radial bases functions (RBFs). Three representative kinds of RBF were chosen: the Hardy’s multiquadratic, inverse multiquadratic, Duchon’s functions. The room acoustic field with uniform, impedance walls was considered. To achieve the goal, relationships among physical parameters of the problem and parameters of the approximate solution were first found. Physical parameters constitute the sound absorption coefficient of the boundary and the frequency of acoustic vibrations. In turn, parameters of the solution are the kind of RBFs, the number of elements in the series of the solution and the number and distribution of influence points. Next, it was shown that the approximate acoustic field can be calculated using MLM with a priori error assumed. All approximate results, averaged over representative rectangular section of the room, were calculated and then compared to the corresponding accurate results. This way, it was proved that the MLM, based on RBFs, is efficient method in description of acoustic boundary problems with impedance boundary conditions and in all acoustic frequencies.
    Źródło:
    Archives of Acoustics; 2020, 45, 1; 85-92
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Finite Element Modelling of a Flow-Acoustic Coupling in Unbounded Domains
    Autorzy:
    Łojek, Paweł
    Czajka, Ireneusz
    Gołaś, Andrzej
    Powiązania:
    https://bibliotekanauki.pl/articles/1953539.pdf
    Data publikacji:
    2020
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    linearised Euler equations
    LEE
    FEniCS
    finite element method
    non-reflective boundary
    conditions
    open source
    Opis:
    One of the main issues of design process of HVAC systems and ventilation ducts in particular is correct modelling of coupling of the flow field and acoustic field of the air flowing in such systems. Such a coupling can be modelled in many ways, one of them is using linearised Euler equations (LEE). In this paper, the method of solving these equations using finite element method and open source tools is decribed. Equations were transformed into functional and solved using Python language and FEniCS software. The non-reflective boundary condition called buffer layer was also implemented into equations, which allowed modelling of unbounded domains. The issue, influence of flow on wave propagation, could be adressed using LEE equations, as they take non-uniform mean flow into account. The developed tool was verified and results of simulations were compared with analytical solutions, both in one- and two-dimensional cases. The obtained numerical results are very consistent with analytical ones. Furthermore, this paper describes the use of the developed tool for analysing a more complex model. Acoustic wave propagation for the backward-facing step in the presence of flow calculated using Navier-Stokes equations was studied.
    Źródło:
    Archives of Acoustics; 2020, 45, 4; 633-645
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-10 z 10

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