Wyniki wyszukiwania - Biblioteka Nauki

1

Acoustic Attenuation Performance Analysis and Optimisation of Expansion Chamber Coupled Micro-perforated Cylindrical Panel Using Response Surface Method

100%

Alisah M. I. , Ooi L. E. , Ripin Z. M. , Yahaya A. F. , Ho K.

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2021

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tom Vol. 46, No. 3

507--517

EN

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.

2

Timber wolf optimization algorithm for real power loss diminution

100%

Lenin K.

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2020

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tom Vol. 14, No. 1

24--28

EN

In this paper Timber Wolf optimization (TWO) algorithm is proposed to solve optimal reactive power problem. Timber Wolf optimization (TWO) algorithm is modeled based on the social hierarchy and hunting habits of Timber wolf towards finding prey. Based on their fitness values social hierarchy has been replicated by classifying the population of exploration agents. Exploration procedure has been modeled by imitating the hunting actions of timber wolf by using searching, encircling, and attacking the prey. There are three fittest candidate solutions embedded as α, β and γ to lead the population toward capable regions of the exploration space in each iteration of Timber Wolf optimization. Proposed Timber Wolf optimization (TWO) algorithm has been tested in standard IEEE 14, 30 bus test systems and simulation results show the projected algorithm reduced the real power loss efficiently.

3

Effect of Emergence Angle on Acoustic Transmission in a Shallow Sea

88%

Lu Y. , Yang K. , Liu H. , Huang C. , Lu Y. , Yang K. , Liu H. , Huang C.

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nr 1

4

An Improved MSA Model for Evaluating the Sound Transmission Loss of a Rectangular Plate for Diffuse Field Incidence

88%

Kim M.-J. , Won K.-S. , Ri C.-S. , Kim M.-J. , Won K.-S. , Ri C.-S.

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5

Sensor Hop-based Energy Efficient Networking Approach for Routing in Underwater Acoustic Communication

88%

Kohli S. , Bhattacharya P. P.

Journal of Telecommunications and Information Technology

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2017

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tom nr 1

44--49

EN

Underwater Wireless Sensor Networks are deployed to explore the world under the water, measure different parameters and communicate the data to the surface, in the widespread applications. The main operating technology of these networks is the acoustic communication. The communication among the sensors and finally to the surface station requires a routing protocol. The sensors being battery limited and unfeasible to be replaced under the water requires an energy efficient routing protocol. Clustering imparted in routing is an energy saving technique in sensor networks. The routing may involve single or multi hop communication in the sensor networks. The paper gives a comparative study of the benchmark protocol multi-hop LEACH with the proposed Sensor Hop-based Energy Efficient Networking Approach (SHEENA) for the shallow as well as deep water in three dimensional Underwater Wireless Sensor Networks. The network energy model for the Underwater Wireless Sensor Networks is based among the different acoustic channel characteristics. The proposed approach is found to give better response.

6

Acoustic Attenuation Performance Analysis and Optimisation of Expansion Chamber Coupled Micro-perforated Cylindrical Panel Using Response Surface Method

88%

Alisah M. I. , Ooi L.-E. , Ripin Z. M. , Yahaya A. F. , Ho K. , Alisah M. I. , Ooi L.-E. , Ripin Z. M. , Yahaya A. F. , Ho K.

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7

Selection of Plate Components of Operator's Cabin Walls in Aspect of Thermal Insulation and Transmission Loss

88%

Dziechciowski Z.

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nr 1

8

Analysis of the Influencing Factors of the Acoustic Performance of the Muffler Considering Acoustic-structural Coupling

75%

Zhao B. , Li H.

Archives of Acoustics

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2022

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tom Vol. 47, No. 4

479--490

EN

In the calculation of the acoustic performance of mufflers, the walls of mufflers are usually treated rigidly without considering the acoustic-structural coupling, but the results so calculated differ significantly from the actual situation. Based on the basic equations, the article derives the finite element equations of the muffler system while considering the acoustic-structural coupling effect and theoretically analyses the connection between the acoustic-structural coupling system and the structural and acoustic modes. The structural and acoustic modes of the muffler are calculated and the reasons for the mutation of the transmission loss curve of the muffler when the acoustic-structural coupling is considered are analysed. The results show that the acoustic-structural coupling is the result of the interaction between the structure and the air inside the expansion chamber under acoustic excitation, which manifests mutations in the sound pressure inside the muffler in some frequency bands. Then, using a single-chamber muffler as an example, the transmission loss is used to characterise the performance of the muffler. The effects of different factors such as shell thickness, structure, porous media material lining, and restraint method on the acoustic-structural coupling effect of the muffler are analysed, and the structure of a double-chamber muffler is successfully optimised according to the conclusions.

9

Modelowanie izolacyjności akustycznej przegród jednorodnych

75%

Majkut L. , Olszewski R.

Autobusy : technika, eksploatacja, systemy transportowe

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2018

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tom R. 19, nr 12

553--556

PL

W artykule opisano podstawowe metody teoretycznego wyznaczania izolacyjności akustycznej właściwej przegród jednorodnych. W pracy autorzy rozważania ograniczyli do modeli opartych na wykorzystaniu impedancji mechanicznej przegrody. Przegrodę zamodelowano jako: bryła sztywna, odkształcalna płyta cienka (opisana modelem Kirchhoffa-Love’a) i gruba (model Mindlina–Reissnera). Wartości izolacyjności akustycznej uzyskane dla tak opisanych modeli porównano dla kilku materiałów stosowanych na obudowy maszyn.

EN

In the paper basic theoretical models of transmission loss calculation are described. Here only single homogeneous isotropic panels are analysed. Three impedance values of one rigid and two flexible body models of panel are described and analysed. As flexible models the thin plate (Kirchhoff-Love plate model) i thick (Mindlin-Reissner model) are analysed.

10

Local model of plane acoustic waves propagation in multilayered infinite sandwich structures

75%

Karczmarzyk S.

Archives of Mechanics

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2011

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tom Vol. 63, nr 5-6

573-573

EN

A local model for computing the coincidence frequencies and the transmission loss of multilayered infinite sandwich plates composed of isotropic layers is presented in the paper. The model is derived within the local theory of linear elastodynamics under assumption that only one component of the vector potential is equivalent to zero and after application of the Pythagorean theorem. Any simplifications concerning the structure have not been introduced. A passage from the acoustic model to some plate benchmark models is shown. Numerical results predicted by the model for homogeneous, three-layer sandwich and five-layer sandwich infinite-infinite plates are obtained and compared with the results predicted by other models existing in the literature. Both flexural and breathing waves are numerically analysed. Some conclusions of practical importance have also been formulated.

11

Transmission loss of absorptive mufflers lined with expanded clay granulates

75%

Kosała K.

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tom Vol. 33, nr 2

art. no. 2022216

EN

The article presents the results of tests on sound attenuation by two types of cylindrical absorptive mufflers with the same length and different diameters of chambers filled with expanded clay granulates. Using a laboratory stand for testing acoustic mufflers with an impedance tube, the transmission loss parameter was determined. To compare the effectiveness of sound attenuation, the transmission loss of mufflers without sound absorbing material was also determined. The results of these tests were compared to the results obtained with the use of a known calculation model for reflective mufflers. Using an impedance tube, the normal incidence sound absorption coefficients of the expanded clay granulates with thicknesses of material samples from 10 to 100 mm were determined. The dependence between the sample thickness and the first resonance frequency of the sound absorption coefficient was determined, which was then used in the proposed calculation model of the effectiveness of the cylindrical absorptive mufflers with expanded clay granulates. Using the proposed theoretical model, the results of transmission loss calculations, satisfactory for engineering applications, were obtained.

12

Analytical and Computational Acoustic Modelling of Side Outlet Muffler and Its Extension in the Modelling of Tapered Side Outlet Muffler

75%

Vishwakarma S. K. , Pawar J.

Archives of Acoustics

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2022

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tom Vol. 47, No. 4

491--499

EN

Mufflers are popular in the suppression of noise levels coming from various machinery. The most common parameters for the evaluation of the performance of mufflers are transmission loss, noise level, and insertion loss. The transmission loss is evaluated for tapered side outlet muffler using finite element analysis without considering the fluid-structure interaction. This study includes analytical modelling and acoustic modelling of the side outlet muffler and transmission loss is in excellent agreement with the reference paper. The feasibility of the acoustic model is also verified with the experimental work on simple expansion chamber muffler. The same finite element analysis is extended for the tapered side outlet muffler. The transmission loss of the tapered side outlet muffler in the given frequency range is found 8.96 dB better than the side outlet muffler. The acoustic pressure level and sound pressure level contours for the tapered side outlet muffler give a clear picture of wave propagation inside the muffler. The effect of the cut-off frequency on the transmission loss of the tapered side outlet muffler can be seen from the contours. This study can be helpful in the determination of the performance of the mufflers in terms of transmission loss, the performance of mufflers above cut-off frequency, and design improvements in the muffler to avoid the higher-order modes of the sound wave.

13

Analiza możliwości wykorzystania współczesnych metod transmisji danych w systemach łączności podwodnej

63%

Lasota H. , Kochańska I.

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tom Vol. 48, nr 9

53-56

PL

Postęp w telekomunikacji szerokopasmowej jest rezultatem rozwoju cyfrowych technik modulacji i kodowania, coraz lepiej wykorzystujących możliwości i przezwyciężających fizyczne ograniczenia przewodowych torów transmisyjnych i kanałów radiowych. Adaptacja metod transmisji danych do komunikacji podwodnej na falach akustycznych wymaga uwzględnienia specyficznych cech kanału hydroakustycznego, który łączy w sobie najtrudniejsze cechy kanałów telekomunikacyjnych. W celu pokazania możliwości wykorzystania w łączności podwodnej osiągnięć współczesnej telekomunikacji dokonano porównania istotnych własności kanałów radiowych, przewodowych i podwodnych. Wytypowano techniki modulacji stosowane w szybkich szerokopasmowych łączach telekomunikacyjnych, których aplikacja w łączności podwodnej wydaje się najbardziej uzasadniona.

EN

The progress in broadband telecommunications results from the development of digital modulation and coding techniques that are better and better matched to communication capabilities and physical limitations of cable and radio transmission channels. The adaptation of data transmission methods to underwater acoustic communications needs to consider specific features of hydroacoustic channels as they shear the most difficult features of telecommunication channels. A short comparison of radio, cable and underwater channels has been made for analysis of possibility of data transmission in underwater environment possibilities. Modulation techniques used in fast broadband telecommunication links, that seem to be suitable for underwater communications, has been indicated.

14

Muffler design with baffle effect and performations on transmission loss

63%

Kamarkhani S. , Mahmoudi Kohan A.

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2018

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tom Vol. 22, nr 4

1337--1343

EN

A typical sound generated by vibrational waves is usually based on the experience and design experience, which can be enhanced by optimizing the internal structure of the exhaust system. The use of baffles and perforations has a significant effect on reducing the transmission loss in a silencer exhaust system. In order to evaluate the response effect of a silencer, the effect of baffle and perforations, without baffles and perforations, was evaluated in COMSOL5.2 software. Which results in numerical results with close experimental results and the effect of buffaloes and perforations, have shown a good reduction in transmissibility, and their partial differences are due to the features of geometry design.

15

Design of Nonwoven Carpets to Upgrade Sound Isolation Features in Automobiles

63%

Atakan R. , Karakaş H. , Sezer S. , İpek S. , Aravi I. , Yıldırım C. , Şen E.

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2014

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tom Vol. 14, no. 4

270--280

EN

With the increases of the expected properties of textile products, better and advanced new designs are being created. Textiles used in vehicles are increasing, and the current performance of the expectations bar is determined by automobile manufacturers. While meeting the expectations of users in the vehicle mechanically, but also disturbing the user during operation of the mechanical properties of this ratio should be minimized. This study was intended to minimize sound transmission of nonwoven textile components, which are used in cars as silencer parts. For that purpose, four different models were developed in this study. First model consists of three designs for baggage carpets. Second model has six designs for floor coverings. Third model comprises two designs inner dash felt and finally fourth model includes two designs of hood liners. The acoustical absorption coefficients and transmission loss of these carpets were tested and evaluated in the frequency range of 16-6300 Hz. The measurements demonstrated that nonwoven layer is a very significant and effective part of a carpet due to its contribution in the sound isolation. With this study, it has been determined which layer has better performance on sound absorption and transmission loss among different carpet types. A combination of heavy layer and nonwoven layer carpets is found to be benefit for noise and sound insulation.

16

Analysis of the combustion engine exhaust system structure in aspect of shaping acoustic energy

63%

Gągorowski A.

Combustion Engines

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2023

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tom R. 62, nr 2

112--116

EN

The flow of exhaust gases is the source of many physical processes, including thermal, acoustic, mechanical and chemical phenomena with high dynamics of changes. The study analyzes the impact of the entire structure of the exhaust system on the formation of acoustic energy, determining the transmission loss characteristics of its individual components and the entire system. On the example of a structure based on a proprietary solution of an adjustable reactive muffler, the possibilities of shaping the flow of acoustic waves in the process of designing and selecting exhaust systems for internal combustion engines were determined. The study was carried out with the use of the CFD method and a specialized package for advanced simulations AVL AST.

17

Metody obliczania izolacyjności akustycznej struktur wielowarstwowych

63%

Bajdała P.

Czasopismo Techniczne. Mechanika

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2011

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tom R. 108, z. 3-M

3-11

PL

Istotnym elementem wpływającym na warunki pracy operatora maszyny roboczej jest rozkład pola akustycznego w kabinie. Decydujący wpływ będzie miała struktura ścian kabiny. W niniejszej pracy zajęto się problematyką określania izolacyjności akustycznej takich struktur. Obliczenia przeprowadzono zgodnie z algorytmem zaczerpniętym z literatury.

EN

A significant element which has influence on the workplace conditions comfort of the heavy duty machine operator is sound field distribution in the cabin. The wall cab structure has a crucial impact. This paper addresses the problem of determining the transmission loss of such structures. The calculation was provided according to algorithms from literature sources.

18

Transmission loss and pressure drop of selected range of helicoidal resonators

63%

Łapka W.

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tom Vol. 26

121--128

EN

The paper presents the numerical analysis of transmission loss and pressure drop of acoustic helicoidal resonators with constant pitch to cylindrical duct diameter ratio and different number of helicoidal turns n. The ducted system consists of a straight cylindrical duct of constant diameter d=0.125m. The ratio of helicoidal pitch s to cylindrical duct diameter d equals s/d=1,976. Other geometrical relationships of helicoidal resonator, as a mandrel diameter dm to duct diameter ratio dm/d=0.024 and thickness g of helicoidal profile g/d=0.0024, were constant as well. The investigated range of numbers of helicoidal turns n was analyzed in the range from 0 to 2.0 for transmission loss parameter and from 0 to 1.0 for pressure drop. The values of normal inflow velocity v [m/s] equals 1, 5, 10, 15 and 20.

19

Modelowanie izolacyjności akustycznej przegród warstwowych

63%

Majkut L.

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tom R. 20, nr 12

170--169

PL

W artykule, do wyznaczania izolacyjności akustycznej przegród warstwowych, wykorzystano podstawowe metody teoretycznego wyznaczania izolacyjności akustycznej właściwej przegród jednorodnych. Niezbędne do obliczeń wartości wielkości wykorzystywanych w modelach wyznaczono w wyniku homogenizacji. W pracy autor rozważania ograniczył do modeli opartych na wykorzystaniu impedancji mechanicznej przegrody. Przegrodę zamodelowano jako: bryła sztywna, odkształcalna płyta cienka (opisana modelem Kirchhoffa-Love’a) i gruba (model Mindlina-Reissnera).

EN

In the paper basic theoretical models of transmission loss calculation are described. Four different methods of homogenisation used for building of the simplified panel model are describeb. Simplified model is the single homogeneous isotropic plate panel. For this panel three impedance values of one rigid and two flexible body models of panel are described and analysed. As flexible models the thin plate (Kirchhoff-Love plate model) i thick (Mindlin-Reissner model) are analysed. All results are compared to results of 3D FEM model.

20

Sound insulation analysis of plates with piezoceramic elements

51%

Kozupa M. , Batko W. , Pietrzko S.

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2007

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tom Vol. 26, no. 4

169-173

EN

This paper represents general idea research to the possibilities of increasing sound insulation of plates by active control it’s vibration through piezoceramic elements placed on the plane. In the preliminary research a rectangular plate 455x560 mm made of steal was analyzed. Sound insulation measurement was executed on a specialized enclosure in reverberation chamber. A PZT piezoceramic was proposed to control vibration of the plate.

PL

Praca przedstawia ogólną koncepcję badań dotyczących analizy możliwości zwiększenia dźwiękoizolacyjności przegród poprzez aktywne sterowanie ich drganiami za pomocą elementów piezolektrycznych rozmieszczonych na ich powierzchni. We wstępnych badaniach analizowano zachowania przegrody w postaci płyty prostokątnej o wymiarach 455 x 560 mm, wykonanej z blachy stalowej. Pomiary dźwiękoizolacyjności wykonano na specjalizowanym stanowisku w komorze pogłosowej. Do sterowania drganiami przegrody zaproponowano elementy piezoceramiczne PZT-4D.