Hasil untuk "Acoustics in engineering. Acoustical engineering"

Le Liu, Long-Xiang Xie, Weichun Huang et al.

Sound absorption is important for room acoustics and remediation of noise. Acoustic metamaterials have recently emerged as one of the most promising platforms for sound absorption. However, the working bandwidth is severely limited because of the strong dispersion in the spectrum caused by local resonance. Utilizing the coupling effect among resonators can improve the absorbers' performance, but the requirement of collecting coupling effects among all resonators, not only the nearest-neighbor coupling, makes the system too complex to explore analytically. This Letter describes deep learning based acoustic metamaterials for achieving broadband sound absorption with no visible oscillation in a targeted frequency band. We numerically and experimentally achieve an average absorption coefficient larger than 97% within the ultra-broadband extending from 860 to 8000 Hz, proving the validity of the deep learning based acoustic metamaterials. The excellent ultra-broadband and near-perfect absorption performance allows the absorber for versatile applications in noise-control engineering and room acoustics. Our work also reveals the significance of modulating coupling effects among resonators, and the deep learning approach may blaze a trail in the design strategy of acoustic functional devices.

Mahmut Biçer, K. Balram

Guiding and manipulating GHz frequency acoustic waves in $\mu \text{m}$ -scale waveguides and resonators open up new degrees of freedom to manipulate radio frequency (RF) signals in chip-scale platforms. A critical requirement for enabling high-performance devices is the demonstration of low acoustic dissipation in these highly confined geometries. In this work, we show that gallium nitride (GaN) on silicon carbide (SiC) supports low-loss acoustics by demonstrating acoustic microring resonators with frequency-quality factor ( $\textit {fQ}$ ) products approaching ${10}^{{13}}$ Hz at 3.4 GHz. The low dissipation measured exceeds the $\textit {fQ}$ bound set by the simplified isotropic Akhiezer material damping limit of GaN. We use this low-loss acoustics platform to demonstrate spiral delay lines with on-chip RF delays exceeding $2.5 ~\mu \text{s}$ , corresponding to an equivalent electromagnetic delay of $\approx 750$ m. Given GaN is a well-established semiconductor with high electron mobility, this work opens up the prospect of engineering traveling wave acoustoelectric interactions in $\mu \text{m}$ -scale waveguide geometries, with associated implications for chip-scale RF signal processing.

Zhuhao Wu, Lingyu Sun, Hanxu Chen et al.

The controllable manipulation and transfer of droplets are fundamental in a wide range of chemical reactions and even life processes. Herein, we present a novel, universal, and straightforward acoustic approach to fabricating biomimetic surfaces for on-demand droplet manipulations like many natural creatures. Based on the capillary waves induced by surface acoustic waves, various polymer films could be deformed into pre-designed structures, such as parallel grooves and grid-like patterns. These structured and functionalized surfaces exhibit impressive ability in droplet transportation and water collection, respectively. Besides these static surfaces, the tunability of acoustics could also endow polymer surfaces with dynamic controllability for droplet manipulations, including programming wettability, mitigating droplet evaporation, and accelerating chemical reactions. Our approach is capable of achieving universal surface manufacturing and droplet manipulation simultaneously, which simplifies the fabrication process and eliminates the need for additional chemical modifications. Thus, we believe that our acoustic-derived surfaces and technologies could provide a unique perspective for various applications, including microreactor integration, biochemical reaction control, tissue engineering, and so on.

Vivek Ahuja, Daniel S. Little, J. Majdalani et al.

This study focuses on the integration of established acoustic prediction techniques directly into a surface-vorticity solver. The main objective is to enhance an aircraft designer's ability to characterize the acoustic signatures generated by urban air mobility (UAM) vehicles in general, and Distributed Electric Propulsion (DEP) concepts in particular, including Unmanned Aerial Vehicles (UAVs). Our solver consists of a reliable, surface-vorticity panel code that incorporates viscous boundary-layer corrections. It thus offers a computationally efficient commercial tool for conceptual design and preliminary aerodynamic analysis. By implementing the Farassat F1A acoustics formulation directly into the solver, a new intuitive capability is achieved, which is both conversive with modern engineering tools and efficient in setup and speed of execution. Besides its application to the X-57 High-Lift Propeller and the Revolutionary Vertical Lift Technology (RVLT) Tiltwing electric Vertical Take-Off and Landing (eVTOL) vehicle by the National Aeronautics and Space Administration (NASA), this capability is systematically demonstrated using three particular case studies. These consist of both single- and six-propeller Joby S4 eVTOL as well as a small eight-propeller Kittyhawk KH-H1 DEP vehicle. Whereas the details of this tool and underlying equations are showcased in this article, the acoustic metrics that can be effectively used to characterize the noise level generated by a UAM in flight are described in a companion article. By embedding this assortment of insightful metrics into a simple and user-friendly flow solver, a much improved flow-acoustic analysis capability is thereby provided to support the design of future aircraft.

B. Schultz, A. Vogel

PURPOSE The human voice changes with the progression of neurological disease and the onset of diseases that affect articulators, often decreasing the effectiveness of communication. These changes can be objectively measured using signal processing techniques that extract acoustic features. When measuring acoustic features, there are often several steps and assumptions that might be known to experts in acoustics and phonetics, but are less transparent for other disciplines (e.g., clinical medicine, speech pathology, engineering, and data science). This tutorial describes these signal processing techniques, explicitly outlines the underlying steps for accurate measurement, and discusses the implications of clinical acoustic markers. CONCLUSIONS We establish a vocabulary using straightforward terms, provide visualizations to achieve common ground, and guide understanding for those outside the domains of acoustics and auditory signal processing. Where possible, we highlight the best practices for measuring clinical acoustic markers and suggest resources for obtaining and further understanding these measures.

Haesang Yang, Keunhwa Lee, Youngmin Choo et al.

: Underwater acoustics that is the study of the phenomenon of underwater wave propagation and its interaction with boundaries, has mainly been applied to the fields of underwater communication, target detection, marine resources, marine environment, and underwater sound sources. Based on the scientific and engineering understanding of acoustic signals/data, recent studies combining traditional and data-driven machine learning methods have shown continuous progress. Machine learning, represented by deep learning, has shown unprecedented success in a variety of fields, owing to big data, graphical processor unit computing, and advances in algorithms. Although machine learning has not yet been implemented in every single field of underwater acoustics, it will be used more actively in the future in line with the ongoing development and overwhelming achievements of this method. To understand the research trends of machine learning applications in underwater acoustics, the general theoretical background of several related machine learning techniques is introduced in this paper.

W. Zhu, W. Shen, Emre Barlas et al.

Zhaoju Yang, Fei Gao, Yahui Yang et al.

C. Erbe

Papatya Nur Dokmeci Yorukoglu, Jian Kang

S. Bilbao

H. Schmalle, Dirk Noy, S. Feistel et al.

M. Åbom

William Bergeron-Mirsky, Jason Lim, John Gulliford et al.

Ronald A. Roy

Y. Bahei-El-din, M. Tawfik

Research in advanced materials is progressing on many fronts with significant developments in composite, smart and nano-scale materials. Industrial applications have also benefited from advances in material science and engineering. Substantial work, however, lies ahead to integrate advanced materials in engineering applications. One such application which has significant impact on both the economy and quality of life is acoustics and vibrations of materials and mechanical systems. Generally, however, materials and dynamics are considered by different groups with little or no interaction. The purpose of the International Conference on Advanced Materials for Application in Acoustics and Vibration (AMAAV)—held in Cairo, Egypt from January 4 to 6, 2009—was to bridge the gap between research and application in the significant field of dynamics, with emphasis on materials, by bringing together regional and international researchers and engineers to present and discuss recent developments in utilizing advanced materials in applications related to acoustics and vibration. It provided a forum for disseminating the latest research findings in material development, modeling, and testing under service loads and environments, derived from real life applications in which acoustics and vibrations play a major role in their design and performance. This special issue of Advances in Acoustics and Vibration contains papers contributed to AMAAV conference. The contributions contained in this issue address both purely dynamic problems and dynamics of/advanced materials. In the latter category, Buonsanti et al. investigate detection of defects in carbon/epoxy composites using ultrasonic testing, and Eldalil and Baz study active control of cylindrical shells subjected to internal pressure pulse using piezoelectric materials. Vibration problems are investigated in four contributed papers; Buonsanti et al. considered the effect of railway-induced vibrations on buildings; Di Mino et al. also considered vibrations caused by railways and investigated the role of open trenches in their reduction; Eldalil and Baz studied the effect of periodic stiffeners on the dynamic stability of cylindrical shells subjected to internal pressure pulse; Patwari et al. presented amethod for dynamic characterization of vertical machining. In acoustics, Ivansson considered the design of acoustic frequency insulators using phononic crystals. The time and effort spent by the authors in participating in the meeting and preparing the manuscripts for this special issue is greatly appreciated.

J. Cipolla

Denzil Taylor Smith

Peter Theobald, S. Robinson, A. Thompson et al.

K. Jensen, E. Arens, L. Zagreus