Applied sciences

Archives of Acoustics

Content

Archives of Acoustics | 2015 | vol. 40 | No 2 |

Abstract

This work presents a simulation of the response of packets of microbubbles in an ultrasonic pulse-echo scan line. Rayleigh-Plesset equation has been used to predict the echo from numerically obtained radial dynamics of microbubbles. Varying the number of scattering microbubbles on the pulse wave form has been discussed. To improve microbubble-specific imaging at high frequencies, the subharmonic and second harmonic signals from individual microbubbles as well as microbubbles packets were simulated as a function of size and pressure. Two different modes of harmonic generation have been distinguished. The strength and bandwidth of the subharmonic component in the scattering spectrum of microbubbles is greater than that of the second harmonic. The pressure spectra provide quantitative and detailed information on the dynamic behaviour of ultrasound contrast agent microbubbles packet.
Go to article

Abstract

This study investigates several factors that have not been specified in the standard for dynamic stiffness, compressibility, and long-term deformation; these factors can be used to evaluate the acoustic and physical performances of resilient materials. The study is intended to provide basic data for deriving the factors that need to be additionally reviewed through the standards. Since magnitude of dynamic stiffness changes with an increase in loading time, it is necessary to examine the setting of the loading time for a load plate under test conditions. Samples of size 300×300 mm, rather than 200×200 mm, yielded more reliable results for compressibility measurement. Since the test to infer long-term deformation of resilient materials after a period of 10 years in some samples showed variation characteristics different from those specified in the standards, it is recommended that the test method should be reviewed through ongoing research.
Go to article

Abstract

The main aim of this paper is to examine the variability of some dynamic properties of concrete composite panels to in-plane eccentric compression loads via static and dynamic impact testing. First, experimental tests were performed in order to obtain the dynamic and static properties of concrete composite panels. In-plane eccentric loads were statically applied to a couple of panels in ten uniform steps. For each step, dynamic impact testing was performed and the modal damping, peak amplitude and natural frequencies obtained. Second, a ‘hybrid’ model, based on the concepts of modal analysis and the Finite Element Method, was developed in order to obtain the natural frequencies and corresponding normal modes of the composite panels within the frequency range 0–200 Hz. For this model, an initial warp of the panel middle surface was incorporated into the formulation in order to represent the applied flexural moment provoked by the eccentric in-plane loads. The accuracy of the ‘hybrid’ model was verified by comparison with the experimental results. Third, comparison is made between predictions (using on the ‘hybrid’ model) and experimental results.
Go to article

Abstract

The paper formulates some objections to the methods of evaluation of uncertainty in noise measurement which are presented in two standards: ISO 9612 (2009) and DIN 45641 (1990). In particular, it focuses on approximation of an equivalent sound level by a function which depends on the arithmetic average of sound levels. Depending on the nature of a random sample the exact value of the equivalent sound level may be significantly different from an approximate one, which might lead to erroneous estimation of the uncertainty of noise indicators. The article presents an analysis of this problem and the adequacy of the solution depending on the type of a random sample.
Go to article

Abstract

This paper describes a Deep Belief Neural Network (DBNN) and Bidirectional Long-Short Term Memory (LSTM) hybrid used as an acoustic model for Speech Recognition. It was demonstrated by many independent researchers that DBNNs exhibit superior performance to other known machine learning frameworks in terms of speech recognition accuracy. Their superiority comes from the fact that these are deep learning networks. However, a trained DBNN is simply a feed-forward network with no internal memory, unlike Recurrent Neural Networks (RNNs) which are Turing complete and do posses internal memory, thus allowing them to make use of longer context. In this paper, an experiment is performed to make a hybrid of a DBNN with an advanced bidirectional RNN used to process its output. Results show that the use of the new DBNN-BLSTM hybrid as the acoustic model for the Large Vocabulary Continuous Speech Recognition (LVCSR) increases word recognition accuracy. However, the new model has many parameters and in some cases it may suffer performance issues in real-time applications.
Go to article

Abstract

This article discusses a system of recognition of acoustic signals of loaded synchronous motor. This software can recognize various types of incipient failures by means of analysis of the acoustic signals. Proposed approach uses the acoustic signals generated by loaded synchronous motor. A plan of study of the acoustic signals of loaded synchronous motor is proposed. Studies include following states: healthy loaded synchronous motor, loaded synchronous motor with shorted stator coil, loaded synchronous motor with shorted stator coil and broken coil, loaded synchronous motor with shorted stator coil and two broken coils. The methods such as FFT, method of selection of amplitudes of frequencies (MSAF-5), Linear Support Vector Machine were used to identify specific state of the motor. The proposed approach can keep high recognition rate and reduce the maintenance cost of synchronous motors.
Go to article

Abstract

This article presents an efficient method of modelling acoustic phenomena for real-time applications such as computer games. Simplified models of reflections, transmission, and medium attenuation are described along with assessments conducted by a professional sound designer. The article introduces representation of sound phenomena using digital filters for further digital audio processing.
Go to article

Abstract

The aim of the study was to determine the configuration of pathologic audiograms in patients with excessive noise exposure, and to calculate the frequency of notches in the audiogram in patients with and without excessive noise exposure by avoiding the effect of age-related hearing loss. We have analyzed 514 audiograms of 257 patients aged between 20 to 50 years: 240 patients (mean age of 38.7 years) with excessive noise exposure and 17 patients (mean age of 41.2 years) with notches in the audiogram, but without a history of excessive noise exposure. For statistical data analysis we have used the Chi-square test and Fisher exact test with the level of significance p < 0.05. Pathologic audiograms were classified into five different types: Slope at 4000 Hz (0.8%), Slope at 2000 Hz (15.1%), Notch at 4000 Hz (67.4%), Notch at 2000 Hz (0.8%), Flat (8.9%), and 7% were out of this classification. A total of 190 (79.2%) patients with excessive noise exposure had a notch in the audiogram. Left ear notches were the most common. Among the patients with notched audiograms, 91.8% had a history of excessive noise exposure, either occupational or nonoccupational, and 8.2% did not report any excessive noise exposure.
Go to article

Abstract

Applying rigorous analytical methods, formulas describing the sound radiation have been obtained for the wedge region bounded by two transverse baffles with a common edge and bottom. It has been assumed that the surface sound source is located at the bottom. The presented formulas can be used to calculate the sound pressure and power inside the wedge region. They are valid for any value of the wedge angle and represent a generalization of the formulas describing the sound radiation inside the two and three-wall corner region. Moreover, the presented formulas can be easily adapted for any case when more than one sound source is located at the bottom. To demonstrate their practical application, the distribution of the sound pressure modulus and the sound power have been analyzed in the case of a rectangular piston located at the wedge’s bottom. The influence of the transverse baffle on the sound power has been investigated. Based on the obtained formulas, the behaviour of acoustic fields inside a wedge can be predicted.
Go to article

Abstract

The present study was conducted in the lobbies of 16 Taiwanese urban hospitals to establish what contributes to the degree of noisiness experienced by patients and those accompanying them. Noise level measurements were then conducted by 15 min equivalent sound pressure levels (LAeq, 15m, dB) during daytime hours. The average LAeq itself was found to be poorly related to perceived noisiness. Levels variations were better correlated, more continual noise may actually be perceived as noisier. According to the findings of a multiple linear stepwise regression model (r = 0.91, R2 = 0.83), the 3 independent variables shown to have the largest effects on perceived noisiness were 1) 1/(L5 − L95), 2) effective duration of the normalized autocorrelation function (τe, h), of all LAeq, 15m over 9–17, and 3) percentile loudness, N5, 15m. These results resemble previous studies that had assumed that a larger fluctuation of noise level corresponds to less annoyance experienced for mixed traffic noise studied in a laboratory situation. As an advanced approach, for hospital noise that consisted of 12 audible noise events, subjective noisiness were evaluated by the noise time structure analyzed by autocorrelation with loudness and levels variation.
Go to article

Abstract

It is convenient to have a device and a method of generating single cut-on modes in cylindrical hard-walled waveguides or at least in laboratory models of such systems. This allows to examine, among other things, properties of various active and/or passive elements inserted in a cylindrical duct by testing them in conditions when the incident (input) wave comprises only one cut-on mode and determining the reflection and transmission coefficients for single selected incident modes. As it has been already demonstrated by the present authors, it is possible to generate single cut-on modes in a circular duct using a small (although increasing with mode order) number of acoustic monopoles arranged properly on a duct cross-section and driven with appropriate acoustic volume amplitudes and phases. Laboratory models of such sources are proposed in this paper and results of tests verifying their directional properties are presented. The other technical issue relating to practical utilization of the proposed method is the possible error introduced by the apparatus used for scanning the acoustic field inside the duct model. It is shown that insertion of the measuring probe changes the total energy radiated into the free space only by a fraction of a decibel.
Go to article

Abstract

In this paper, the MFC sensor and actuators are applied to suppress circular plate vibrations. It is assumed that the system to be regulated is unknown. The mathematical model of the plate was obtained on the base of registration of a system response on a fixed excitation. For the estimation of the system’s behaviour the ARX identification method was used to derive the linear model in the form of a transfer function of the order nine. The obtained model is then used to develop the linear feedback control algorithm for the cancellation of vibration by using the MFC star-shaped actuator (SIMO system). The MFC elements location is dealt with in this study with the use of a laser scanning vibrometer. The control schemes presented have the ability to compute the control effort and to apply it to the actuator within one sampling period. This control scheme is then illustrated through some numerical examples with simulations modelling the designed controller. The paper also describes the experimental results of the designed control system. Finally, the results obtained for the considered plate show that in the chosen frequency limit the designed structure of a closed-loop system with MFC elements provides a substantial vibration suppression.
Go to article

Abstract

The paper presents the results of the noise propagation analysis in ship structures tested in a number of AHTS (Anchor Handling Tug Supply) vessels. Statistical Energy Analysis (SEA) based on numerical model developed specially for the purpose of this numerical investigation were conducted. This numerical model enabled the analysis of both the structural elements and the acoustic spaces. For the detailed studies 47 points fixed at various ship locations were selected. Prediction results with use of the numerical model were compared with the experimental results carried out in six identical AHTS vessels. Experimental studies were performed in accordance with the requirements of the International Maritime Organization (IMO) Resolution A.468 (XII). As a result one presented a comparison of the model analysis and experimental tests results.
Go to article

Abstract

This paper presents a theoretical study of the propagation behaviour of surface Love waves in nonhomogeneous functionally graded elastic materials, which is a vital problem in acoustics. The elastic properties (shear modulus) of a semi-infinite elastic half-space vary monotonically with the depth (distance from the surface of the material). Two Love wave waveguide structures are analyzed: 1) a nonhomogeneous elastic surface layer deposited on a homogeneous elastic substrate, and 2) a semi-infinite nonhomogeneous elastic half-space. The Direct Sturm-Liouville Problem that describes the propagation of Love waves in nonhomogeneous elastic functionally graded materials is formulated and solved 1) analytically in the case of the step profile, exponential profile and 1cosh2 type profile, and 2) numerically in the case of the power type profiles (i.e. linear and quadratic), by using two numerical methods: i.e. a) Finite Difference Method, and b) Haskell-Thompson Transfer Matrix Method. The dispersion curves of phase and group velocity of surface Love waves in inhomogeneous elastic graded materials are evaluated. The integral formula for the group velocity of Love waves in nonhomogeneous elastic graded materials has been established. The results obtained in this paper can give a deeper insight into the nature of Love waves propagation in elastic nonhomogeneous functionally graded materials.
Go to article

Abstract

The main objective of this study is to improve the ultrasound image by employing a new algorithm based on transducer array element beam pattern correction implemented in the synthetic transmit aperture (STA) method combined with emission of mutually orthogonal complementary Golay sequences. Orthogonal Golay sequences can be transmitted and received by different transducer elements simultaneously, thereby decreasing the time of image reconstruction, which plays an important role in medical diagnostic imaging. The paper presents the preliminary results of computer simulation of the synthetic aperture method combined with the orthogonal Golay sequences in a linear transducer array. The transmission of long waveforms characterized by a particular autocorrelation function allows to increase the total energy of the transmitted signal without increasing the peak pressure. It can also improve the signal-to-noise ratio and increase the visualization depth maintaining the ultrasound image resolution. In the work, the 128-element linear transducer array with a 0.3 mm pitch excited by 8-bits Golay coded sequences as well as one cycle at nominal frequencies of 4 MHz were used. The comparison of 2D ultrasound images of the phantoms is presented to demonstrate the benefits of a coded transmission. The image reconstruction was performed using the synthetic STA algorithm with transmit and receive signals correction based on a single element directivity function.
Go to article

Editorial office

Editorial Board
Editor-in-Chief
Andrzej Nowicki (Institute of Fundamental Technological Research PAN, Warszawa)
Deputy Editor-in-Chief
Barbara Gambin (Institute of Fundamental Technological Research PAN, Warszawa)
Associate Editors
Genaral linear acoustics and physical acoustics
• Wojciech P. Rdzanek (University of Rzeszów, Rzeszów)
• Anna Snakowska (AGH University of Science and Technology, Kraków)
Architectural acoustics
• Tadeusz Kamisiński (AGH University of Science and Technology, Kraków)
Musical acoustics and psychological acoustics
• Andrzej Miśkiewicz (The Fryderyk Chopin University of Music, Warszawa)
• Anna Preis (Adam Mickiewicz University, Poznań)
Underwater acoustics and nonlinear acoustics
• Grażyna Grelowska (Gdańsk University of Technology, Gdańsk)
Speech, Computational acoustics and signal processing
• Ryszard Gubrynowicz (Polish-Japanese Institute of Information Technology, Warszawa)
Ultrasonics, transducers and instrumentation
• Krzysztof Opieliński (Wrocław University of Technology, Wrocław)
Electroacoustics
• Jan Żera (Warsaw University of Technology, Warszawa)
Noise control and environmental acoustics
• Jan Adamczyk (AGH University of Science and Technology, Kraków)
• Mirosław Meissner (Institute of Fundamental Technological Research PAN, Warszawa)
• Janusz Kompała (Central Mining Institute, Katowice)
Secretary
• Izabela Ewa Mika

Contact

Archives of Acoustics
Institute of Fundamental Technological Research
5b Pawińskiego Str.,
02-106 Warszawa, Poland
Phone: (48) (22) 826 12 81 ext. 206
Fax: (48) (22) 826 98 15
Email: akustyka@ippt.gov.pl

Support Contact
Paweł Witkowski
Email: intools@intools.pl

Instructions for authors

Author Guidelines
• Manuscripts intended for publication in Archives of Acoustics should be submitted in pdf format by an on-line procedure.
• Manuscript should be original, and should not be submitted either previously or simultaneously elsewhere, neither in whole, nor in part.
• Submitted papers must be written in good English and proofread by a native speaker.
• Basically, the papers should not exceed 40 000 typographic signs.
• Postal addresses, affiliations and email addresses for each author are required.
• Detailed information see Article Requirements.
• Manuscript should be accompanied by a cover letter containing the information:
o why the paper is submitted to ARCHIVES OF ACOUSTICS,
o suggestion on the field of acoustics related to the topic of the submitted paper,
o the statement that the manuscript is original, the submission has not been previously published, nor was sent to another journal for consideration,
o 3–5 names of suggested reviewers together with their affiliations, full postal and e-mail addresses; at least 3 suggested reviewers should be affiliated with other scientific institutions than the affiliations of the authors,
o author’s suggestion to classification of the paper as the research paper, review paper or technical note.

Article Requirements
1. At submission time only a PDF file is required. After acceptance, authors must submit all source material (see information about Figures). Authors can use their preferred manuscript-preparation software. The journal itself is produced in LaTeX, so accepted articles will be converted to LaTeX at production time.
2. The title of the paper should be as short as possible.
3. Full names and surnames should be given.
4. The full postal address of each affiliation, including the country name should be provided. Affiliations should contain the full postal address, as well as an e-mail address of one author designated as corresponding author.
5. The text should be preceded by a concise abstract (less than 200 words).
6. Keywords should be given.
7. The formulae to be numbered are those referred to in the paper, as well as the final formulae.
8. All notations should be written very distinctly.
9. References in the text (author(s) and year of publication) are to be cited between parentheses.
Items appearing in the reference list should be complete, including surname and the initials of the first name of the author, the full title of the paper/book in English followed by the information on the original paper language. In case of a book, the publisher's name, the place and year of publication should be given. In case of a periodical, the full title of the periodical, consecutive volume number, current issue number, pages, and year of publication should be given. All references in the bibliography should be cited in the text, and arranged in alphabetical order by authors' last name.
For more information on references see http://acoustics.ippt.gov.pl/public/Instructions.pdf.
10. Figures must be of publication quality. Each figure should be saved in separate file and captioned and numbered so that it can float. After acceptance, Authors will need to submit the original source files for all photos, diagrams and graphs in manuscript.
For diagrams and graphs vector EPS or vector PDF files are the most useful. Make sure that what you're saving is vector graphics and not a bitmap. Please also include the original data for any plots. This is particularly important if you are unable to save Excel-generated plots in vector format. Saving them as bitmaps is not useful; please send the Excel (.xls) spreadsheets instead.
Photographs should be high-quality – with resolution no lower than 300 dpi.
Pack all figure files into a single archive (zip, tar, rar or other format) and then upload on the magazine web site.

This page uses 'cookies'. Learn more