Artykuły w czasopismach: „Vibrations-Acoustics”

1

Richardson, Bernard E. "Good vibrations (musical acoustics)". Physics Education 25, nr 1 (1.01.1990): 35–40. http://dx.doi.org/10.1088/0031-9120/25/1/006.

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Festa, Maurizio, Frank Stalter, Arm Tavornmas i Frank Gauterin. "Human Response to Vehicle Vibrations and Acoustics during Transient Road Excitations". Vibration 4, nr 2 (8.04.2021): 357–68. http://dx.doi.org/10.3390/vibration4020023.

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Driving over rising and falling edges on roads and pavements, rails, manhole covers, or transverse joints can influence the driving impression regarding the driver’s perception of vibrations and acoustics. To be able to describe this, objective parameters are used to make the subjective ride comfort measurable and scalable. Previous studies have already contributed to the investigation of the subjective perception regarding the interaction of vibrations and acoustics. However, the results were individual. Aimed at improving the quality of objective analysis methods, driving maneuvers were performed in a real vehicle to investigate the interaction of vibrations and acoustics due to transient road excitations. For this purpose, a sound reproduction system was used, which could provide the acoustic environment for the driver to adapt to while driving. With this method, subjective ratings by varying vibrations and acoustics were collected and with reference to objective parameters statistically evaluated. The results showed that both tactile and audible vibrations under transient influences had no significant interactive effects on the driver’s perception.

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Jasinski, Christopher M., i Robert D. Celmer. "Effective educational practices, assessment, and applications in acoustics and vibration at the University of Hartford". Journal of the Acoustical Society of America 152, nr 1 (lipiec 2022): 633–39. http://dx.doi.org/10.1121/10.0012697.

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The University of Hartford is home to two unique undergraduate engineering majors in acoustics, both sharing a core course layout of acoustics, vibrations, and projects. The Bachelor of Science in Mechanical Engineering with an Acoustics Concentration and the Bachelor of Science in Engineering in Acoustical Engineering and Music programs allow for two complementary tracks within the acoustics field, providing cohesive plans of study on many facets of listening and design. All Mechanical Engineering majors (regardless of concentration) are required to take Vibrations I and a course in Engineering and Environmental Acoustics. The department philosophy for this inclusion is that acoustics and vibration design considerations are an essential component for the development of the complete mechanical engineer. This paper outlines program educational goals and outcomes, along with pedagogical adjustments made based on continuous assessment and evaluation of select courses, including recent changes to adapt to measured deficiencies. The paper also details the historical development of the acoustics program, components of the Vibrations I and Engineering & Environmental Acoustics courses, and example research and design projects based on work in these courses. Among the included projects are modal analysis, community room acoustics assessment, and an open access computational room acoustics simulator for use and collaboration with colleagues in acoustics education.

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Newland, David E. "Harmonic wavelets in vibrations and acoustics". Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences 357, nr 1760 (wrzesień 1999): 2607–25. http://dx.doi.org/10.1098/rsta.1999.0451.

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Ginsberg, Jerry H. "Fifty five years following a long and winding road through structural acoustics and vibrations". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A209. http://dx.doi.org/10.1121/10.0018678.

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Being an academic at institutions that did not have a dedicated mission in acoustics allowed me to pursue diverse research topics. Probably because of the challenge presented by structural acoustics and vibrations, my efforts were primarily focused in those areas. They proceeded from nonlinear shell theory, to pipeline instability, to nonlinear vibrations, to nonlinear acoustics, to variational methods for acoustic radiation, to shock response of submarines, to experimental modal analysis, to coupled acoustic-structure resonance of a flying telescope with an open cavity. I will attempt to attempt to explain what led me to this progression, and to place these efforts in the context of communal efforts.

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Ginsberg, Jerry. "Hot topics in structural acoustics and vibrations". Journal of the Acoustical Society of America 88, S1 (listopad 1990): S69. http://dx.doi.org/10.1121/1.2029116.

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Hambric, Stephen A. "Structural Acoustics Tutorial—Part 1: Vibrations in Structures". Acoustics Today 2, nr 4 (2006): 21. http://dx.doi.org/10.1121/1.2961142.

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Kaster, Theo, Heinrich Kostyra i Torsten Treyde. "Acoustics and vibrations on steering and braking systems". ATZ worldwide 107, nr 9 (wrzesień 2005): 12–14. http://dx.doi.org/10.1007/bf03224761.

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Tournat, Vincent. "Graduate studies in acoustics and wave physics at Institut d’Acoustique - Graduate School, Le Mans, France". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A125. http://dx.doi.org/10.1121/10.0015766.

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This poster presents the graduate studies in Acoustics at Le Mans (France) offered at the “Institut d’Acoustique - Graduate School”. Graduate studies in Acoustics at Le Mans University have been awarded in 2018 the excellence label “École Universitaire de Recherche” among 28 other reference centers for all fields of Science, through a highly selective national call. Our master and engineering school programs range from physical acoustics, environmental acoustics, acoustics and vibrations to international masters on electro-acoustics and on wave physics. The education through research is carried out at the LAUM, UMR CNRS, one of the largest acoustics laboratory in the world. Several details, objectives, student feedbacks and contact informations on the graduates studies will be given on the poster.

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Shariff, Yasir M. "Acoustics Vibrations to Enhance Flow Boiling in Micro Channels". International Journal of Thermal and Environmental Engineering 2, nr 1 (15.12.2010): 19–25. http://dx.doi.org/10.5383/ijtee.02.01.003.

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Feit, D., i A. D. Pierce. "Acoustics 1994: Vibrations and acoustical response of fuzzy structures". Journal of the Acoustical Society of America 97, nr 1 (styczeń 1995): 705. http://dx.doi.org/10.1121/1.412296.

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Jasinski, Christopher M. "Early development of a vibrations concept inventory for undergraduate acoustics education". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A147. http://dx.doi.org/10.1121/10.0018456.

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Vibrations I is a required course for all mechanical engineering majors at the University of Hartford (including those in the Acoustics concentration). This builds upon a mechanics sequence from the second-year curriculum including Statics and Dynamics. While the current course layout has proven successful in achieving the program’s intended outcomes for accreditation, some non-Acoustics majors have been observed to be missing some important concepts that are not routinely evaluated in exam questions. In order to understand these issues more clearly, a concept inventory for vibrations is being developed. A concept inventory is a multiple-choice assessment designed to evaluate students’ understanding of the underlying concepts regarding course material. The assessment is designed in such a way that the student is challenged to determine the outcome of a scenario related to course material, and many questions will specifically target common misconceptions held by students in mechanical engineering programs. This type of assessment has been used frequently since the original Force Concept Inventory from Hestenes et al. (1985). This presentation will describe some of the initial work towards developing this inventory, discuss alternative assessments, and will welcome input from the Education in Acoustics community on how to best move forward with this idea.

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RIOU, HERVÉ, PIERRE LADEVEZE i BENJAMIN SOURCIS. "THE MULTISCALE VTCR APPROACH APPLIED TO ACOUSTICS PROBLEMS". Journal of Computational Acoustics 16, nr 04 (grudzień 2008): 487–505. http://dx.doi.org/10.1142/s0218396x08003750.

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An approach, called the "Variational Theory of Complex Rays," was proposed recently for calculating the vibrations of slightly damped elastic structures in the medium-frequency range. One key feature of this approach is the use of a new variational formulation of the vibration problem which allows the shape functions to be discontinuous across element boundaries, thus giving this strategy great flexibility and robustness. This method was fully developed for structural vibrations. In this paper, we apply it to acoustics problems. Examples of two-dimensional Helmholtz problems show that this method is very robust and accurate yet requires much less computational effort than the finite element method, which enables one to use it up to much higher frequencies.

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McDaniel, James G. "Historical development of damping models in structural acoustics and vibrations". Journal of the Acoustical Society of America 144, nr 3 (wrzesień 2018): 1862. http://dx.doi.org/10.1121/1.5068186.

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Weaver, Richard. "Random matrix theory and complexity in structural acoustics and vibrations". Journal of the Acoustical Society of America 141, nr 5 (maj 2017): 3907. http://dx.doi.org/10.1121/1.4988808.

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Wixom, Andrew S. "Generalized polynomial chaos based surrogate models for acoustics and vibrations". Journal of the Acoustical Society of America 152, nr 4 (październik 2022): A135. http://dx.doi.org/10.1121/10.0015798.

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This work explores generalized polynomial chaos (GPC) surrogate models and their effectiveness for general acoustics and vibration applications. GPC is primarily known as an uncertainty quantification (UQ) technique and in that context the underlying polynomial-based model has been shown to be effective in mapping input probability distributions to the corresponding output probability distributions. In this study, GPC surrogate models – including those generated by both quadrature and regression methods – are evaluated for their effectiveness in non-UQ focused analyses. As points of comparison, Krylov subspace and other more traditional reduced order modeling techniques are demonstrated and compared to GPC models so that the differences may be better understood. Example problems with several different levels of complexity are used to show how the computational burden as well as the overall effectiveness of the method changes as the number of input variables that must be considered grows.

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Xi, Jinxiang, Mohamed Talaat, Xiuhua Si i Haibo Dong. "Flow Dynamics and Acoustics from Glottal Vibrations at Different Frequencies". Acoustics 4, nr 4 (28.10.2022): 915–33. http://dx.doi.org/10.3390/acoustics4040056.

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Glottal vibration is fundamental to breathing-related disorders and respiratory sound generation. However, responses of the flow and acoustics to glottal vibrations of different frequencies are unclear. The objective of this study is to numerically evaluate the influences of glottal vibration frequencies on inspiratory airflow dynamics and flow-induced sound signals; this is different from normal phonation that is driven by controlled expiratory flows. A computational model was developed that comprised an image-based mouth–throat–lung model and a dynamic glottis expanding/contracting following a sinusoidal waveform. Large Eddy simulations were used to solve the temporal and spatial flow evolutions, and pressure signals were analyzed using different transform algorithms (wavelet, Hilbert, Fourier, etc.). Results show that glottal vibrations significantly altered the flows in the glottis and trachea, especially at high frequencies. With increasing vibration frequencies, the vortices decreased in scale and moved from the main flow to the walls. Phase shifts occurred between the glottis motion and glottal flow rates for all frequencies considered. Due to this phase shift, the pressure forces resisted the glottal motion in the first half of contraction/expansion and assisted the glottal motion in the second half of contraction/expansion. The magnitude of the glottal flow fluctuation was approximately linear with the vibration frequency (~f0), while the normal pressure force increased nonlinearly with the frequency (~f01.85). Instantaneous pressure signals were irregular at low vibration frequencies (10 and 20 Hz) but became more regular with increasing frequencies in the pressure profile, periodicity, and wavelet-transformed parameters. The acoustic characteristics specific to the glottal vibration frequency were explored in temporal and frequency domains, which may be used individually or as a combination in diagnosing vocal fold dysfunction, snoring, sleep apnea, or other breathing-related diseases.

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Hambric, Stephen. "Practical Tutorial on cylindrical structure vibro-acoustics Part 1 - Vibrations". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, nr 7 (1.02.2023): 140–49. http://dx.doi.org/10.3397/in_2022_0026.

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The mathematics which describe the vibroacoustic behavior of cylindrical structures are imposing to say the least. Part 1 of this practical tutorial demystifies cylindrical shell vibration theory by using measured data from actual shells and pipes to explain key concepts. For any shell, you can estimate frequency ranges where shells behave like simple beams and flat plates, greatly simplifying calculations of modes of vibration and mobilities. The key is first calculating the ring frequency - the frequency where membrane waves can propagate fully around the shell circumference. Simple infinite structure theory may then be used to compute mean mobilities for beam, shell, and flat plate behavior. Modes of vibration for a cylinder depend on both longitudinal and circumferential harmonics, or a helical wavenumber. Cremer's simple approximate resonance frequency formula is used to show examples for a large diameter short shell and a small diameter long shell (a pipe). Finally, the measured modal densities of an elbowed pipe are compared to estimates from an empirical expression for modal density of a shell. In all cases in this tutorial, measurements and simple estimates agree well, showing that cylindrical shell vibrations may be estimated without difficult math or complex computer models.

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Ryan, Teresa J., Diego Turo, Joseph F. Vignola i John A. Judge. "Using acoustics and vibrations to teach experimental concepts and technical communications". Journal of the Acoustical Society of America 137, nr 4 (kwiecień 2015): 2289. http://dx.doi.org/10.1121/1.4920356.

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French, R. M. "Mechanics of Vibro-Acoustics Series. USING GUITARS TO TEACH VIBRATIONS AND ACOUSTICS. ARTICLE 4: PSYCHOACOUSTICS AND SOUND QUALITY". Experimental Techniques 29, nr 2 (marzec 2005): 47–48. http://dx.doi.org/10.1111/j.1747-1567.2005.tb00214.x.

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Koch, Robert M. "Trends in the 40 + -year development of advanced structural acoustic and vibration computational modeling". Journal of the Acoustical Society of America 153, nr 3_supplement (1.03.2023): A208. http://dx.doi.org/10.1121/10.0018676.

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Over the course of the past 40-45 years of computational modeling in the fields of structures, structural acoustics, and vibrations, there have been extreme advancements made in numerous areas that have greatly increased and improved the size, accuracy, efficiency, and complexity of numerical solutions possible. Most of this progress has been made through a combination of improvements in the distinct areas of computer processing approaches/speed and available memory, primarily evolutionary enhancements in detailed numerical material and continuum mechanics models, development of entirely new physics-based numerical vibroacoustic modeling approaches, etc. This paper presents a historical review of the detailed progress made in computational structural acoustics and vibration from the “early days” in the 1980s through current state-of-the-art advanced numerical approaches, much of which would not have been dreamed possible back four decades ago! While most of the examples utilized in this talk are pulled from the speaker’s specific technical area of undersea vehicle/ system structural acoustics, the overall trends presented are certainly represented across the broad spectrum of vibro-acoustics modeling applications.

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Rillig, Matthias C., Karine Bonneval i Johannes Lehmann. "Sounds of Soil: A New World of Interactions under Our Feet?" Soil Systems 3, nr 3 (14.07.2019): 45. http://dx.doi.org/10.3390/soilsystems3030045.

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Soils are biodiversity-dense and constantly carry chemical flows of information, with our mental image of soil being dark and quiet. But what if soil biota tap sound, or more generally, vibrations as a source of information? Vibrations are produced by soil biota, and there is accumulating evidence that such vibrations, including sound, may also be perceived. We here argue for potential advantages of sound/vibration detection, which likely revolve around detection of potential danger, e.g., predators. Substantial methodological retooling will be necessary to capture this form of information, since sound-related equipment is not standard in soils labs, and in fact this topic is very much at the fringes of the classical soil research at present. Sound, if firmly established as a mode of information exchange in soil, could be useful in an ‘acoustics-based’ precision agriculture as a means of assessing aspects of soil biodiversity, and the topic of sound pollution could move into focus for soil biota and processes.

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Feit, David, Murray Strasberg i Eric E. Ungar. "History of structural acoustics and vibrations in the Acoustical Society of America". Journal of the Acoustical Society of America 111, nr 5 (2002): 2405. http://dx.doi.org/10.1121/1.4778194.

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Ducceschi, Michele, i Stefan Bilbao. "Linear stiff string vibrations in musical acoustics: Assessment and comparison of models". Journal of the Acoustical Society of America 140, nr 4 (październik 2016): 2445–54. http://dx.doi.org/10.1121/1.4962553.

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Echeverria‐Villagomez, Salvador, i Alfredo Elias‐Juarez. "Elements for a conformity assessment system in acoustics, vibrations and ultrasound in Mexico". Journal of the Acoustical Society of America 112, nr 5 (listopad 2002): 2411–12. http://dx.doi.org/10.1121/1.4779851.

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Pierce, Allan D., i Martin G. Manley. "Ray acoustics models for sound radiation from vibrations of fluid‐loaded circular shells". Journal of the Acoustical Society of America 87, S1 (maj 1990): S49—S50. http://dx.doi.org/10.1121/1.2028249.

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Allen, John S., Rafsan Rabbi, Akihito Kiyama i Tadd Truscott. "Acoustics of Drop Impact on Hydrophobic Surfaces and Liquid Pools". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A62. http://dx.doi.org/10.1121/10.0010660.

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Drop impact on surfaces has been studied comprehensively as it has a wide range of fundamental and practical implications. The splash, spreading, and rebound have been investigated with respect to substrate interfaces with hydrophobic surfaces being of particular interest. However, impact on wetted substrates is less understood for the hydrophobic surfaces. Also the associated acoustics of the drop impact has not be explored in terms of air entrainment and substrate vibrations. We investigate the impact of water drops (∼2–10 mm diameter) from heights 100–400 cm upon hydrophilic– and hydrophobic–coated solid surfaces as well as free floating liquid pools (0.15–0.45 ml). A contact microphone coated with the Glaxco water repellant provides a hydrophobic surface upon which impact vibrations can be quantified. An air microphone is synchronized to a high-speed Phantom camera for sound recording and optical visualization of the impact and rebound phases. Cross-correlation of the two microphones reveals distinct differences between the two solid substrates. The initial rebound and subsequent jet break-up are found in an analysis of the signal’s amplitude and phase. These results are compared to those from gel spheres and discussed for applications of non-contact coating monitoring.

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Citarella, Roberto, Luigi Federico i Mattia Barbarino. "Aeroacustic and Vibroacoustic Advancement in Aerospace and Automotive Systems". Applied Sciences 10, nr 11 (1.06.2020): 3853. http://dx.doi.org/10.3390/app10113853.

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This Special Issue highlights the latest enhancements in the abatement of noise and vibrations of aerospace and automotive systems. The reduction of acoustic emissions and the improvement of cabin interior comfort are on the path of all major transportation industries, having a direct impact on customer satisfaction and, consequently, the commercial success of new products. Topics covered in this Special Issue deal with computational, instrumentation and data analysis of noise and vibrations of fixed wing aircrafts, satellites, spacecrafts, automotives and trains, ranging from aerodynamically generated noise to engine noise, sound absorption, cabin acoustic treatments, duct acoustics and vibroacoustic properties of materials. The focus of this Special Issue is also related to industrial aspects, e.g.,: numerical and experimental studies have been performed for an existing and commercialized engine to enable design improvements aimed at reducing noise and vibrations; moreover, an optimization is provided for the design of low vibroacoustic volute centrifugal compressors and fans whose fluids should be strictly kept in the system without any leakage. Existing procedures and algorithms useful to reach the abovementioned objectives in the most efficient way are illustrated in the collected papers.

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Krylov, V. V. "Spectra of Low-Frequency Ground Vibrations Generated by High-Speed Trains on Layered Ground". Journal of Low Frequency Noise, Vibration and Active Control 16, nr 4 (grudzień 1997): 257–70. http://dx.doi.org/10.1177/026309239701600404.

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Increase in speeds of modern railway trains is usually accompanied by higher levels of generated ground vibrations. In the author's earlier paper [V.V. Krylov, Applied Acoustics, 44, 149–164 (1995)], it has been shown that especially large increase in vibration level may occur if train speeds v exceed the velocity of Rayleigh surface waves in the ground cR., i.e., v > cR. Such a situation might arise, for example, with French TGV trains for which speeds over 515 km/h have been achieved. The present paper investigates the effect of geological layered structure of the ground on ground vibrations generated by high-speed trains. It is shown that, since Rayleigh wave velocities in layered ground are dispersive and normally increase at lower frequencies associated with deeper penetration of surface wave energy into the ground, the trans-Rayleigh condition v > cR may not hold at very low frequencies. This will cause a noticeable reduction in low-frequency components of generated ground vibration spectra. Theoretical results are illustrated by numerically calculated frequency spectra of ground vibrations generated by single axle loads travelling at different speeds and by TGV or Eurostar high-speed trains.

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Lucas, M., A. Gachagan i A. Cardoni. "Research applications and opportunities in power ultrasonics". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 223, nr 12 (21.10.2009): 2949–65. http://dx.doi.org/10.1243/09544062jmes1671.

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The first applications in power ultrasonics were largely focused on ultrasonic cleaning baths, which rely on generating inertial cavitation, and the incorporation of ultrasonic excitation in manufacturing processes such as joining of plastics and metals. Since the early days of power ultrasonics there has been a rapid growth in the number of applications, and the diversified range of applications, from microwelding to ultrasonic osteotomy, has been made possible by a combination of advances in experimental techniques for characterizing low ultrasonic frequency vibrations and acoustics, and advances in computational modelling. This article highlights just some of the research in power ultrasonics that aims to exploit the benefits of low ultrasonic frequency high ultrasonic amplitude vibrations. This article reports current research and suggests future opportunities in three different application areas that have seen significant recent advances: joining and shaping of metals, surgical devices, and cavitation cells.

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Bischof, Wolfgang, Florian Draeger, Martin Hennen i Ralph Kennel. "Operating Point Adaptation for NVH-Optimization of Induction Machines". World Electric Vehicle Journal 9, nr 1 (7.06.2018): 10. http://dx.doi.org/10.3390/wevj9010010.

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Inverter-fed drive systems are mostly optimized to operate at the best efficiency, neglecting the possibility of acoustic optimization. The chosen operating point can lead to undesired harmonics involving vibrations and noises of the electrical drive. In order to optimize the system with respect to acoustics, the given operating point for best efficiency is left and a noise, vibration and harshness (NVH)-optimized operating point is chosen. This paper shows the influence of the operating point on NVH, describes an NVH-optimized control and draws a comparison between simulation and measurement.

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Echeverría‐Villagomez, J. S. "Traceability of acoustics and vibrations standards at the National Center of Metrology in Mexico". Journal of the Acoustical Society of America 96, nr 5 (listopad 1994): 3271. http://dx.doi.org/10.1121/1.410951.

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Saleh, Yusuf, Muhammad Sani Yahya i Aliyu Bukar Dala. "Vibro-Acoustics for Reli-ability Modeling of Un-derwater Pipeline using Wireless Sensor Network (WSN), with Minimum Energy Consumption". International Journal of Engineering & Technology 7, nr 3.36 (6.05.2018): 118. http://dx.doi.org/10.14419/ijet.v7i3.36.29090.

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WSN is a network of clusters of sensors nodes which sense the parameter and communicates to a server. Target is to develop underwater pipeline monitoring system remotely with lower energy consumption. Reliability maintenance will effectively give optimum performance of pipeline system operation. Reliability ensures optimum performance in the range of operation based on the behavior of the system. Validation of the mathematical model for the flow in pipeline system is used to study vibrations as elements that affect the reliability of the pipeline. In this, the focus is to validate and model the reliability for the pipeline system from the vibrations for predictive maintenance and optimum performance. Subsequently, vibro-acoustics will be used to model the reliability equation. A software can be developed for simulating the reliability model for pipeline system behavior from the vibration factors and use for predictive maintenance. Reliability factors of mean time to failure, repair and others will be put in to use to develop the original model for the pipeline. A hypothesis of 90% predictive model from the reliability under pipeline system behavior will be developed.

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Kasess, Christian H., Thomas Maly, Piotr Majdak i Holger Waubke. "Effects of rumble strip parameters on acoustics, vibration, and perception". Acta Acustica 5 (2021): 54. http://dx.doi.org/10.1051/aacus/2021047.

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Rumble strips aim to alert the driver of dangerous situations via acoustic and tactile stimulation. They can, however, also lead to increased noise in the surroundings. Strip parameters and the vehicle type determines the size of these acoustic and vibratory effects. In our work, 16 rumble strip types (including strips with irregular spacing) were evaluated with respect to their effects on acoustics, vibration, and perception. Interior and exterior emissions caused by controlled pass-overs of a car and a truck were recorded. Annoyance, urgency, and reaction time of 16 listeners were tested in a laboratory experiment and models mapping acoustics to perception were developed. Steering wheel and seat vibrations were acquired. Our results show a high correlation of interior and exterior noise. The loudness level was the best predictor of perceived annoyance and urgency. Irregular spacing reduced the tonality at the cost of a difficult production process. While a large variety of strip types produced a sufficient acoustic effect in the passenger car, the acoustic response was lower in the truck. Combined with the low vibration levels found in the truck, an identification of an optimal strip type for both vehicle types turns out to be difficult.

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Berthelot, Yves H. "Hot topics in structural acoustics: Optical imaging of surface vibrations—Some new developments and applications". Journal of the Acoustical Society of America 109, nr 5 (maj 2001): 2424. http://dx.doi.org/10.1121/1.4744584.

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Duda, Tobias, Christoph Mülder, Georg Jacobs, Kay Hameyer, Dennis Bosse i Martin Cardaun. "Integration of electromagnetic finite element models in a multibody simulation to evaluate vibrations in direct-drive generators". Forschung im Ingenieurwesen 85, nr 2 (30.03.2021): 257–64. http://dx.doi.org/10.1007/s10010-021-00472-z.

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AbstractThis paper introduces a novel electromechanical model for calculating electromagnetic excited structural vibrations and structure borne acoustics for gearless wind turbines. Therefore, the wind turbine model structure is explained and a drivetrain model is derived to investigate the drivetrain decoupled from the aerodynamic excitations. The drivetrain model is fed with results from an electromagnetic finite element model of the generator considering air gap width changes and the wind turbine torque and speed characteristics. Furthermore, an exemplary ramp-up of the drivetrain is simulated. It can be seen, that generator structure oscillations are excited during certain rotational speeds, which may be relevant for the acoustic behavior of the turbine.

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Jasinski, Christopher M., i Robert Celmer. "Acoustics and vibrations as an integral part of the engineering curriculum at the University of Hartford". Journal of the Acoustical Society of America 150, nr 4 (październik 2021): A291. http://dx.doi.org/10.1121/10.0008326.

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Hodges, C. H., J. Power i J. Woodhouse. "The use of the sonogram in structural acoustics and an application to the vibrations of cylindrical shells". Journal of Sound and Vibration 101, nr 2 (lipiec 1985): 203–18. http://dx.doi.org/10.1016/s0022-460x(85)81216-5.

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Zechmann, Edward. "Advancing support for cause-and-effect models by estimating the kurtosis statistic using fractional-octave-band filters". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 264, nr 1 (24.06.2022): 247–58. http://dx.doi.org/10.3397/nc-2022-725.

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This paper presents a preliminary method for estimating signal processing parameters that optimally satisfies accuracy and resolution requirements for the sound pressure level and kurtosis level. The kurtosis statistic has long been studied and more recently used for applications in acoustics and vibrations such as architectural acoustics, hearing loss, noise exposure, and accelerated material and structural life testing. The temporal and spectral characteristics of many quantities are evident by time-frequency analysis including hearing, finger sensation, sound diffusion, and reverberation. Some research has conditioned on frequency content while other research has not. Simpson's reversal may potentially adversely affect the models if frequency content is not considered. Modeling techniques which relate cause-and-effect are more likely to result in successful models. Models of human hearing are particularly sensitive to the frequency content because the tonotopic organization of the cochlea induces a cause-and-effect relationship from sound incident on the ear to the basilar membrane. The fractional-octave-band filters specified in ANSI S1.11 and IEC 61260-1 are well developed for conditioning on frequency bands. This paper provides details of the process for optimizing the filter parameters. Additional optimization and testing is described for developing a faster and more accurate method with better support for causal inference.

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40

Guan, Shane, i Samuel L. Denes. "Acoustic impact studies and assessments by Bureau of Ocean Energy Management on offshore wind development". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A238—A239. http://dx.doi.org/10.1121/10.0011184.

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The U.S. Bureau of Ocean Energy Management (BOEM) manages the exploration and development of offshore energy resources, including offshore wind development, on the U.S. Outer Continental Shelf. Construction, operation, and decommissioning of offshore wind facilities generate intense or long-lasting underwater sounds and vibrations that may be detrimental to marine life. This presentation will provide an overview of the activities that BOEM is in engaging in to address these impacts. BOEM’s Environmental Studies Program (ESP) has been developing funding and managing numerous studies to understand sound field characteristics and sound propagation from pile driving and geophysical surveys related to offshore wind development, as well as marine species responses to these activities. In addition, BOEM established the Center for Marine Acoustics (CMA) to strengthen its role as a driving force within the regulatory community on sound in the marine environment and provides acoustical expertise within the environmental permitting process. The CMA continues to provide guidance on the development of best practices for the use of acoustics in the evaluating the effects of offshore wind on marine fauna. This presentation will highlight the relevant acoustic studies and explain how BOEM is using the science to better manage noise impacts on the ocean environment.

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41

Johns, D. J. "Proceedings Review : VIBRATIONS IN BUILDINGS Institute of Acoustics, St. Albans, UK Vol. 12, Part 7 1990, 12, $21.70". Shock and Vibration Digest 23, nr 4 (1.04.1991): 14. http://dx.doi.org/10.1177/058310249102300405.

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Bodaghi, Dariush, Qian Xue, Xudong Zheng i Scott Thomson. "Effect of Subglottic Stenosis on Vocal Fold Vibration and Voice Production Using Fluid–Structure–Acoustics Interaction Simulation". Applied Sciences 11, nr 3 (29.01.2021): 1221. http://dx.doi.org/10.3390/app11031221.

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An in-house 3D fluid–structure–acoustic interaction numerical solver was employed to investigate the effect of subglottic stenosis (SGS) on dynamics of glottal flow, vocal fold vibration and acoustics during voice production. The investigation focused on two SGS properties, including severity defined as the percentage of area reduction and location. The results show that SGS affects voice production only when its severity is beyond a threshold, which is at 75% for the glottal flow rate and acoustics, and at 90% for the vocal fold vibrations. Beyond the threshold, the flow rate, vocal fold vibration amplitude and vocal efficiency decrease rapidly with SGS severity, while the skewness quotient, vibration frequency, signal-to-noise ratio and vocal intensity decrease slightly, and the open quotient increases slightly. Changing the location of SGS shows no effect on the dynamics. Further analysis reveals that the effect of SGS on the dynamics is primarily due to its effect on the flow resistance in the entire airway, which is found to be related to the area ratio of glottis to SGS. Below the SGS severity of 75%, which corresponds to an area ratio of glottis to SGS of 0.1, changing the SGS severity only causes very small changes in the area ratio; therefore, its effect on the flow resistance and dynamics is very small. Beyond the SGS severity of 75%, increasing the SGS severity, leads to rapid increases of the area ratio, resulting in rapid changes in the flow resistance and dynamics.

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43

Ysmagul, R. S., i А. Е. Nurgeldina. "METHODS FOR SOLVING FREDHOLM INTEGRAL EQUATIONS". BULLETIN Series of Physics & Mathematical Sciences 69, nr 1 (10.03.2020): 174–78. http://dx.doi.org/10.51889/2020-1.1728-7901.29.

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The article deals with integral equations that are widely used in various sections of physics (theory of waves on the surface of liquids, quantum mechanics, problems of spectroscopy, crystallography, acoustics, analysis and diagnostics of plasma, etc.), Geophysics (problems of gravimetry, kinematic problems of seismics), mechanics (vibrations of structures), etc. When the physics introduced aftereffect, it is not enough ordinary differential equations or partial differential equations, otherwise the initial data would determine the future state. To take into account the continuous sequence of previous States, we need to use integral and integro-differential equations, where the sign of the integral appears functions of parameters that characterize the system, which depend on time for some period preceding the moment under consideration. In this article we have considered the solution of Fredholm integral equations of the second kind by the method of successive approximations and the method of iterated nuclei.

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Liu, Ting-Wei, Chun-Tat Chan i Rih-Teng Wu. "Deep-Learning-Based Acoustic Metamaterial Design for Attenuating Structure-Borne Noise in Auditory Frequency Bands". Materials 16, nr 5 (24.02.2023): 1879. http://dx.doi.org/10.3390/ma16051879.

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In engineering acoustics, the propagation of elastic flexural waves in plate and shell structures is a common transmission path of vibrations and structure-borne noises. Phononic metamaterials with a frequency band gap can effectively block elastic waves in certain frequency ranges, but often require a tedious trial-and-error design process. In recent years, deep neural networks (DNNs) have shown competence in solving various inverse problems. This study proposes a deep-learning-based workflow for phononic plate metamaterial design. The Mindlin plate formulation was used to expedite the forward calculations, and the neural network was trained for inverse design. We showed that, with only 360 sets of data for training and testing, the neural network attained a 2% error in achieving the target band gap, by optimizing five design parameters. The designed metamaterial plate showed a −1 dB/mm omnidirectional attenuation for flexural waves around 3 kHz.

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Walters, Gage, Andrew Wixom i Sheri Martinelli. "Comparison of quadrature and regression based generalized polynomial chaos expansions for structural acoustics". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, nr 6 (1.08.2021): 863–74. http://dx.doi.org/10.3397/in-2021-1670.

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This work performs a direct comparison between generalized polynomial chaos (GPC) expansion techniques applied to structural acoustic problems. Broadly, the GPC techniques are grouped in two categories: , where the stochastic sampling is predetermined according to a quadrature rule; and , where an arbitrary selection of points is used as long as they are a representative sample of the random input. As a baseline comparison, Monte Carlo type simulations are also performed although they take many more sampling points. The test problems considered include both canonical and more applied cases that exemplify the features and types of calculations commonly arising in vibrations and acoustics. A range of different numbers of random input variables are considered. The primary point of comparison between the methods is the number of sampling points they require to generate an accurate GPC expansion. This is due to the general consideration that the most expensive part of a GPC analysis is evaluating the deterministic problem of interest; thus the method with the fewest sampling points will often be the fastest. Accuracy of each GPC expansion is judged using several metrics including basic statistical moments as well as features of the actual reconstructed probability density function.

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Smadi, Mahmoud M., i Mahmoud H. Alrefaei. "New extensions of Rayleigh distribution based on inverted-Weibull and Weibull distributions". International Journal of Electrical and Computer Engineering (IJECE) 11, nr 6 (1.12.2021): 5107. http://dx.doi.org/10.11591/ijece.v11i6.pp5107-5118.

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The Rayleigh distribution was proposed in the fields of acoustics and optics by lord Rayleigh. It has wide applications in communication theory, such as description of instantaneous peak power of received radio signals, i.e. study of vibrations and waves. It has also been used for modeling of wave propagation, radiation, synthetic aperture radar images, and lifetime data in engineering and clinical studies. This work proposes two new extensions of the Rayleigh distribution, namely the Rayleigh inverted-Weibull (RIW) and the Rayleigh Weibull (RW) distributions. Several fundamental properties are derived in this study, these include reliability and hazard functions, moments, quantile function, random number generation, skewness, and kurtosis. The maximum likelihood estimators for the model parameters of the two proposed models are also derived along with the asymptotic confidence intervals. Two real data sets in communication systems and clinical trials are analyzed to illustrate the concept of the proposed extensions. The results demonstrated that the proposed extensions showed better fitting than other extensions and competing models.

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Weaver, Richard. "Localization, Scaling, and Diffuse Transport of Wave Energy in Disordered Media". Applied Mechanics Reviews 49, nr 2 (1.02.1996): 126–35. http://dx.doi.org/10.1115/1.3101886.

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The Anderson localization literature in structural acoustics has to date been concerned largely with applications to the vibrations of one dimensional structures, whether mono-coupled or multi-coupled, and to steady state responses in such systems. This paper presents a brief tutorial on the theory of wave localization in one and higher dimensions with an emphasis on the scaling theory of localization. It then reviews the acoustic and optical literature on wave localization with an emphasis on diffuse time domain responses to transient loads. Numerical and laboratory experiments demonstrating localization in higher dimensions and investigating the time-domain behavior of such systems are discussed. Scaling theory is shown to provide predictions for localization lengths in weakly disordered multi-coupled systems, and for localization lengths in weakly disordered two-dimensional systems as well. Theoretical arguments for rates of diffuse transport are contrasted with the experimental evidence. The paper concludes with a discussion of wave energy confinement in non-localizing disordered systems.

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Gimeno, Encarnación, i Augusto Beléndez. "Rational-Harmonic Balancing Approach to Nonlinear Phenomena Governed by Pendulum-Like Differential Equations". Zeitschrift für Naturforschung A 64, nr 12 (1.12.2009): 819–26. http://dx.doi.org/10.1515/zna-2009-1207.

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This paper presents a new approach for solving accurate approximate analytical solutions for nonlinear phenomena governed by pendulum-like differential equations. The new approach couples Taylor series expansion with rational harmonic balancing. An approximate rational solution depending on a small parameter is considered. After substituting the approximate solution into the governing differential equation, this equation is expanded in Taylor series of the parameter prior to harmonic balancing. The approach gives a cubic equation, which must be solved in order to obtain the value of the small parameter. A method for transforming this cubic equation into a linear equation is presented and discussed. Using this approach, accurate approximate analytical expressions for period and periodic solutions are obtained. We also compared the Fourier series expansions of the analytical approximate solution and the exact one. This allowed us to compare the coefficients for the different harmonic terms in these solutions. These analytical approximations may be of interest for those researchers working in nonlinear physical phenomena governed by pendulum-like differential equations in fields such as classical mechanics, vibrations, acoustics, electromagnetism, electronics, superconductivity, optics, gravitation, and others

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Kim, Cheol Hong, Young Jin Park i Jong-Myon Kim. "Erratum: “Improving mp3 capability of mobile phones by linking acoustics information with vibrations” [J. Acoust. Soc. Am. 126(4), 2185 (2009)]". Journal of the Acoustical Society of America 126, nr 6 (grudzień 2009): 3360. http://dx.doi.org/10.1121/1.3257648.

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García A., Carlos, Nicolas Dauchez i Gautier Lefebvre. "Radiation of thin complex plates estimated with the landscape of localisation theory". Journal of the Acoustical Society of America 151, nr 4 (kwiecień 2022): A167. http://dx.doi.org/10.1121/10.0010996.

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The landscape of localisation is a practical tool that enables the prediction of the geographical localisation of localized modes and helps us to understand the transition between localized and delocalised states. Moreover, approximations based on the Rayleigh quotient and on a variant of Weyl’s law are employed to predict the eigenfrequencies for the Schro ¨ dinger operator in quantum mechanics, but they are also valid for the Laplace and biharmonic operators, which characterize the behaviour of most dynamical systems in acoustics and vibrations. When studying the acoustic radiation from a vibrating structure, three global parameters are key indicators: the mean squared velocity, the acoustic radiated power, and the radiation efficiency. The literature on this subject is very vast for the plate case, where for simple geometries, it is still possible to derive analytical solutions or, at least, very useful approximations. For more complex structures, numerical simulations seem to be appropriate for lack of a simpler solution. In this context, this work aims to give some light to create a direct relationship between these global parameters and the landscape of localisation function, based on the multipolar radiation behaviour presented by localized modes and estimated by geometrical means.

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