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10th Anniversary of Applied Sciences-Invited Papers in Acoustics and...
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10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Acoustics and Vibrations".

Deadline for manuscript submissions: closed (31 March 2021) | Viewed by 15412

Special Issue Editor

Prof. Dr. Dimitrios G. Aggelis

E-Mail Website
Guest Editor
Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
Interests: structural health monitoring (shm); non-destructive evaluation (nde); acoustic emission (ae); ultrasonic testing (ut); scattering; dispersion; attenuation; material evaluation; concrete
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Applied Sciences is going to reach a remarkable milestone by publishing its 10th volume, and in celebration of this special occasion, we have taken the initiative to launch a Special Issue from the Acoustics and Vibrations section called "10th Anniversary of Applied Sciences: Invited Papers in Acoustics Field". The issue will publish invited high-quality original research and review articles related to all aspects and applications of acoustics and elastic waves, as well as vibrations both in their active and passive form.

Since 2014, when Applied Sciences received its first impact factor, the review quality significantly improved; hence, in 2018, 2703 manuscripts were published from 9757 submissions, with an acceptance rate below 28%. This gave the journal an impact factor jump from 1.484 in 2014 to 2.217 in 2018. We have also reduced the manuscript turnaround time; presently, the median publication time is only 37 days, which will be further reduced in the coming months, and we hope to increase the impact factor above 3.0 by the end of 2019. Among all sections of Applied Sciences, the Acoustics and Vibrations section strongly contributes to this success; 655 articles have been published so far, along with 68 Special Issues (data as of 3 December 2019). On this occasion, we would like to thank our all Editorial Board Members, Managing Editors, Reviewers, and Authors for their great contributions and continued support. Please join the celebration of our 10th anniversary and submit your (review) article to the Anniversary Edition.

Prof. Dimitrios G. Aggelis
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Applied Sciences is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (6 papers)

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Research

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17 pages, 5831 KiB  
Article
Adaptive Deterministic Vibration Control of a Piezo-Actuated Active–Passive Isolation Structure
by Feng Li, Shujin Yuan, Fanfan Qian, Zhizheng Wu, Huayan Pu, Min Wang, Jiheng Ding and Yi Sun
Appl. Sci. 2021, 11(8), 3338; https://doi.org/10.3390/app11083338 - 08 Apr 2021
Cited by 7 | Viewed by 2268
Abstract
With the improvement of the performance of optical equipment carried by on-orbit spacecraft, the requirements of vibration isolation are increasing. Passive isolation platforms are widely used, but the ability to suppress the low-frequency deterministic vibration disturbance is limited, especially near the system’s natural [...] Read more.
With the improvement of the performance of optical equipment carried by on-orbit spacecraft, the requirements of vibration isolation are increasing. Passive isolation platforms are widely used, but the ability to suppress the low-frequency deterministic vibration disturbance is limited, especially near the system’s natural frequency. Therefore, an active vibration control strategy is proposed to improve passive isolation performance. In this paper, a Youla parameterized adaptive active vibration control system is introduced to improve the isolation performance of a piezo-actuated active–passive isolation structure. A linear quadratic Gaussian (LQG) central controller is first designed to shape the band-limited local loop of the closed-loop system. Then, the central controller is augmented into a Youla parameterized adaptive regulator with the recursive least square adaptive algorithm, and the Youla parameters (Q parameters) can be adjusted online to the desired value to suppress the unknown and time-varying multifrequency deterministic vibration disturbance. In the experiment, the residual vibration with respect to the combination of multiple frequencies is effectively suppressed by more than 20 dB on average, and a quick response time of less than 0.3 s is achieved when the deterministic residual vibration changes suddenly over time. The experimental results illustrate that the proposed adaptive active vibration control system can effectively suppress the low-frequency deterministic residual vibration. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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18 pages, 9415 KiB  
Article
On the Influence of Reference Mahalanobis Distance Space for Quality Classification of Complex Metal Parts Using Vibrations
by Liangliang Cheng, Vahid Yaghoubi, Wim Van Paepegem and Mathias Kersemans
Appl. Sci. 2020, 10(23), 8620; https://doi.org/10.3390/app10238620 - 02 Dec 2020
Cited by 4 | Viewed by 1520
Abstract
Mahalanobis distance (MD) is a well-known metric in multivariate analysis to separate groups or populations. In the context of the Mahalanobis-Taguchi system (MTS), a set of normal observations are used to obtain their MD values and construct a reference Mahalanobis distance space, for [...] Read more.
Mahalanobis distance (MD) is a well-known metric in multivariate analysis to separate groups or populations. In the context of the Mahalanobis-Taguchi system (MTS), a set of normal observations are used to obtain their MD values and construct a reference Mahalanobis distance space, for which a suitable classification threshold can then be introduced to classify new observations as normal/abnormal. Aiming at enhancing the performance of feature screening and threshold determination in MTS, the authors have recently proposed an integrated Mahalanobis classification system (IMCS) algorithm with robust classification performance. However, the reference MD space considered in either MTS or IMCS is only based on normal samples. In this paper, an investigation on the influence of the reference MD space based on a set of (i) normal samples, (ii) abnormal samples, and (iii) both normal and abnormal samples for classification is performed. The potential of using an alternative MD space is evaluated for sorting complex metallic parts, i.e., good/bad structural quality, based on their broadband vibrational spectra. Results are discussed for a sparse and imbalanced experimental case study of complex-shaped metallic turbine blades with various damage types; a rich and balanced numerical case study of dogbone-cylinders is also considered. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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11 pages, 1503 KiB  
Article
Dental Condition as A Factor Modifying the Transmission of the Sound Vibration in the Skull Bones
by Slawomir Balinski, Monika Morawska-Kochman, Romuald Bolejko, Krzysztof Dudek and Marek Bochnia
Appl. Sci. 2020, 10(18), 6478; https://doi.org/10.3390/app10186478 - 17 Sep 2020
Viewed by 1950
Abstract
Dental deficiencies coexist with hearing loss, and dental treatment can improve hearing acuity. To prove that different dentition affects the transmission of acoustic vibrations through bone conduction, we prepared six dry human skulls to reconstruct teeth and soft tissues. We measured the transmission [...] Read more.
Dental deficiencies coexist with hearing loss, and dental treatment can improve hearing acuity. To prove that different dentition affects the transmission of acoustic vibrations through bone conduction, we prepared six dry human skulls to reconstruct teeth and soft tissues. We measured the transmission of vibrations from the maxilla to the cochlea, in the toothless jaw (TJ), jaw with lateral defects with frame dentures (FD), toothless jaw with complete dentures (CD), and jaw with reconstructed dentition (RD). Each skull was flexibly suspended. The maxilla was stimulated with the bone vibrator Radioear B71. The vibrations of the pyramid were measured perpendicularly using the Polytec PSV-400-M2 scanning vibrometer. Characteristics of frequencies differed simultaneously on the left (l) and right (r) side of each skull. In all states (from 234 Hz to 5 kHz), we identified 10–21 resonant (R) and 9–21 antiresonant (AR) frequencies unilaterally (+/− 5%). In about 30% of cases, they were each time inconsistent with the “physiological” state-RD. In the 500 Hz–2 kHz frequency range (necessary for understanding speech), the effective vibrations velocities vRMS (mm/s) near cochlea were significantly lower in RD than in tree states, where (depending on the dentures) the least energy reached cochlea in FD and the most in TJ. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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23 pages, 7818 KiB  
Article
Development of Ultrasonic Techniques for Measurement of Spatially Non-Uniform Elastic Properties of Thin Plates by Means of a Guided Sub-Sonic A0 Mode
by Rymantas Jonas Kazys, Liudas Mazeika and Justina Sestoke
Appl. Sci. 2020, 10(9), 3299; https://doi.org/10.3390/app10093299 - 09 May 2020
Cited by 6 | Viewed by 1916
Abstract
Air-coupled ultrasonic guided A0 mode is already used for material characterization. By measuring the phase velocity of the A0 mode the elastic properties, such as the Young’s modulus, can be determined. The objective of this work was the development of measurement [...] Read more.
Air-coupled ultrasonic guided A0 mode is already used for material characterization. By measuring the phase velocity of the A0 mode the elastic properties, such as the Young’s modulus, can be determined. The objective of this work was the development of measurement methods and corresponding signal processing procedures enabling the acquisition of spatial distributions of non-uniform elastic properties of thin films and plates. Those methods are based on the excitation of a slow sub-sonic A0 Lamb wave mode in a plate, the measurement of normal displacements at different distances from the source, the formation of the B-scan, and processing the collected signals. Two different signal processing methods were proposed and investigated. In the first method the all zero-crossing instants of the ultrasonic signals at different distances are found and from them spatial distributions of the A0 mode velocity are determined. According to the second method 2D spatial-temporal spectrum of the B-scan is calculated and propagating A0 modes with different velocities are identified. Efficiency of the proposed methods was evaluated theoretically and experimentally using thin mineral MICA paper samples, which is used in the electrical and aerospace industries as an insulating material. The zones with different A0 mode phase velocities (95 ± ∆3 m/s and (106 ± ∆6 m/s) at the frequency 47 kHz were identified. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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12 pages, 2099 KiB  
Article
On the Use of Linear and Nonlinear Controls for Mechanical Systems Subjected to Friction-Induced Vibration
by Baptiste Chomette and Jean-Jacques Sinou
Appl. Sci. 2020, 10(6), 2085; https://doi.org/10.3390/app10062085 - 19 Mar 2020
Cited by 8 | Viewed by 2701
Abstract
Friction-Induced Vibration and noisE (FIVE) is still a complex and nonlinear physical phenomenon which is characterized by the appearance of instabilities and self-sustained vibrations. This undesirable vibrational phenomenon is encountered in numerous industrial applications and can cause major failures for mechanical systems. One [...] Read more.
Friction-Induced Vibration and noisE (FIVE) is still a complex and nonlinear physical phenomenon which is characterized by the appearance of instabilities and self-sustained vibrations. This undesirable vibrational phenomenon is encountered in numerous industrial applications and can cause major failures for mechanical systems. One possibility to limit this vibration phenomenon due to the appearance of instabilities is to add a controller on the system. This study proposes to discuss the efficiency but also limitations of an active control design based on full linearization feedback. In order to achieve this goal, a complete study is performed on a phenomenological mechanical system subjected to mono or multi-instabilities in the presence of friction. Transient and self-excited vibrations of the uncontrolled and controlled systems are compared. More specifically, contributions of linear and nonlinear parts in the control vector for different values of friction coefficient are investigated and the influence of the control gain and sensitivity of the controller to the signal-to-noise ratio are undertaken. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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Review

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44 pages, 4182 KiB  
Review
Dynamic Viscosity and Transverse Ultrasonic Attenuation of Engineering Materials
by Kanji Ono
Appl. Sci. 2020, 10(15), 5265; https://doi.org/10.3390/app10155265 - 30 Jul 2020
Cited by 9 | Viewed by 3204
Abstract
In this paper, ultrasonic attenuation of the transverse waves of engineering materials is evaluated, covering metals, ceramics, polymers, fiber-reinforced plastics, and rocks. After verifying experimental methods, 273 measurements are conducted and their results are tabulated. Fifty of the tests are for the longitudinal [...] Read more.
In this paper, ultrasonic attenuation of the transverse waves of engineering materials is evaluated, covering metals, ceramics, polymers, fiber-reinforced plastics, and rocks. After verifying experimental methods, 273 measurements are conducted and their results are tabulated. Fifty of the tests are for the longitudinal mode. Attenuation behavior is determined over broadband spectra. The attenuation spectra are characterized in four patterns, with 2/3 of the tests showing linear frequency dependence and another ¼ linear spectrum plus Rayleigh scattering (Mason-McSkimin relation). The longitudinal and transverse damping factors varied from 0.004 to 0.065, which are 1/3 to 5 times those of polymethyl methacrylate, suggesting that almost all the engineering materials tested may be viscoelastic. The present test results make the term dynamic viscosity more appropriate for exploring the underlying processes. The observed results were compared between the longitudinal and transverse modes and among similar material types. In more than a half of the tests, the transverse attenuation coefficients were higher than the corresponding longitudinal attenuation coefficients by 1.5× or more. Some material groups had similar attenuation coefficients for the two modes. Since the physical basis for viscous damping is hardly understood, especially in hard solids, further studies from new angles are keenly desired. This collection of new attenuation data will be of value for such works. Practically, this will assist in materials selection and in designing structural health monitoring and non-destructive inspection protocols. Full article
(This article belongs to the Special Issue 10th Anniversary of Applied Sciences-Invited Papers in Acoustics and Vibrations Section)
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