Hasil untuk "Acoustics in engineering. Acoustical engineering"

Aurégan Yves

This paper investigates the acoustic behavior of a perforated pen cap, which acts as a compact self-sustained whistling system. Through experimental measurements and numerical simulations, we analyze the aeroacoustic interaction between jet flow dynamics and resonator geometry to identify conditions under which sound generation and amplification occur. The study highlights key aeroacoustic mechanisms and demonstrates pedagogical value, while suggesting practical implications for the design of flow-induced sound devices.

Baumann Katharina, Gharbi Sirine, Juliust Hessel et al.

While increased sound levels near the ground in downwind conditions are a well-studied topic, comparatively little attention has been given in the literature to increased sound pressure levels in upwind propagation. This increase, however, typically occurs only under specific conditions, including an elevated source location, a non-linear (e.g., logarithmic) wind or temperature profile, and a focus on particular distances within the upwind domain. These conditions are known to be responsible for the formation of caustics. Simultaneously, the sound level enhancement may be disturbed by diffraction, ground reflection, and its characteristics depend on the source structure, being most readily derivable for point sources. Consequently, investigations using models and comparisons with observations are challenging. This work uses two fundamentally different modelling approaches in their ability to capture such phenomena. The goal is to provide an intuitive understanding of the complex interactions involved in sound propagation under real atmospheric conditions, thereby supporting the interpretation of acoustic simulation and measurements in applied contexts.

H. Sinan Bank, Daniel R. Herber

The proliferation of data across the system lifecycle presents both a significant opportunity and a challenge for Engineering Design and Systems Engineering (EDSE). While this "digital thread" has the potential to drive innovation, the fragmented and inaccessible nature of existing datasets hinders method validation, limits reproducibility, and slows research progress. Unlike fields such as computer vision and natural language processing, which benefit from established benchmark ecosystems, engineering design research often relies on small, proprietary, or ad-hoc datasets. This paper addresses this challenge by proposing a systematic framework for a "Map of Datasets in EDSE." The framework is built upon a multi-dimensional taxonomy designed to classify engineering datasets by domain, lifecycle stage, data type, and format, enabling faceted discovery. An architecture for an interactive discovery tool is detailed and demonstrated through a working prototype, employing a knowledge graph data model to capture rich semantic relationships between datasets, tools, and publications. An analysis of the current data landscape reveals underrepresented areas ("data deserts") in early-stage design and system architecture, as well as relatively well-represented areas ("data oases") in predictive maintenance and autonomous systems. The paper identifies key challenges in curation and sustainability and proposes mitigation strategies, laying the groundwork for a dynamic, community-driven resource to accelerate data-centric engineering research.

Haimo Joehri

This paper gives an overview about aspects of mechanical engineering of undulators. It is based mainly on two types that are used in the SwissFEL facility. The U15 Undulator is an example of an in-vacuum type and the UE38 is an APPLE-X type. It describes the frame, the adjustment of the magnets with flexible keepers and the adjustment of the whole device with eccentric movers.

Welerson Kneipp, Antônio André Novotny, Bojan B. Guzina

This work presents a full-waveform reconstruction strategy to identify microseismic events in solid–fluid systems using multi-frequency acoustic pressure measurements collected in the fluid. The goal is to recover both the locations and seismic moment tensors of the events, motivated by applications such as monitoring reaction-induced fracturing in subsurface carbon storage formations. Microseismic sources are modeled as dipole and double-couple point forces embedded in the solid domain. The reconstruction is carried out via a topological derivative approach, in which the leading-order perturbation of a misfit functional is driven by the elastic energy released through the creation of an infinitesimal fracture at a trial location. The forward problem is formulated in the frequency domain, coupling elastodynamics in the solid and acoustics in the fluid. The inversion algorithm combines a discrete grid search, adaptive refinement strategies, and multi-frequency data assimilation. Numerical simulations in two dimensions demonstrate the ability to reconstruct multiple sources using a modest number of hydrophones. The results also highlight the interplay between spatial and spectral aperture, showing that limitations in one can, to a degree, be compensated by abundance in the other.

Reddi Eswari Sravya, S. Anand, Titti Mitesh kumar et al.

Abstract: In smart buildings, energy-efficient HVAC/light control, security and health-aware environments, human occupancy information is critical to these systems. Current methods of sensing human occupancy, such as Passive Infrared (PIR), Carbon Dioxide (CO₂), Radio Frequency (RF) and vision-based systems typically have limitations regarding privacy, visibility restrictions, and limited accuracy when an individual is stationary and expensive and complicated. In this paper, proposes and describe an alternate paradigm for detecting the occupancy of humans by utilizing and analysing low-frequency acoustic signals produced from natural breathing of an individual, micro-movement of the chest and/or body. The current state of the art in acoustic/non-intrusive presence sensing; the physiological properties and characteristics of signals related to bio-acoustics and the use of low-cost MEMS microphones and embedded microcontrollers to provide real-time human occupancy detection applications. Bio-acoustic sensing with traditional methods on several factors as privacy, cost, ability to detect a stationary person, environmental sensitivity. The paper concludes with identifying areas for future research which involve sensor integration, adaptive signal processing, and embedded real-time implementation. The paper concludes by supporting bio-acoustic detection as a feasible, low-cost, privacy-oriented method to detect the presence of people within smart buildings and homes. Keywords: Acoustic signals, Bio-acoustic sensing, Low-frequency, MEMS microphones

Xin‐Yu Cui, Xiu‐Zheng Liu, Peng Wu et al.

High‐precision dynamic manipulation of 3D acoustic fields is a challenge in acoustics, crucial for applications from high‐resolution imaging to targeted therapy. Conventional phased arrays (PAs), while inherently dynamic, are constrained by the size and number of piezo‐elements, which imposes a trade‐off among imaging resolution, aperture size, and system complexity due to the Nyquist sampling theorem. Acoustic lenses, by contrast, can provide subwavelength resolution but are intrinsically static. To reconcile these problems, here, a proposal is made to employ a steerable‐plane‐wave‐excited meta‐lens (SPWL) to combine plane‐wave steering and wavefront reshaping. In SPWL, an acoustic meta‐lens performs the intricate wavefront engineering, while a sparse PA is employed for flexible plane‐wave steering. The strategy circumvents the Nyquist sampling criterion, thereby mitigating severe spatial aliasing which is typically associated with sparse arrays and enabling a low‐cost system to achieve subwavelength focus scanning across both near and far fields. Its versatility is further demonstrated for spatial scanning of structured acoustic beams, including dual‐spot focusing and vortex. Uniting the high performance, tunability and reduced complexity, the proposed SPWL system paves a transformative route toward advanced ultrasonic devices for biomedical applications.

Fangchao Chen, Youhong Xiao, Liang Yu et al.

Accurate reconstruction of three-dimensional acoustic fields from sparse multi-frequency measurements is essential for engineering tasks such as cabin noise control, building-acoustics optimization, and machinery diagnostics. In this study, a frequency-domain physics-informed neural network (PINN) framework is presented, in which the inhomogeneous Helmholtz equation with an explicit monopole source term is embedded into the loss function so that phase-consistent and physically plausible predictions are enforced. To enhance broadband performance under sparse spatial sampling, a multi-branch network architecture with Fourier feature encoding is employed, by which frequency-specialized learning is enabled while model compactness is maintained. The proposed method is validated on a high-fidelity three-dimensional acoustic dataset under varying spatial sampling densities and frequency resolutions. Compared with both the homogeneous-PDE PINN and the purely data-driven baseline, our model reduces RMSE by up to 60 %. It also increases the correlation by 20-60 %across the evaluated frequencies and test sets. Results demonstrate that the PINN achieves superior reconstruction accuracy and generalization across the full frequency spectrum, significantly outperforming the baseline in sparse measurement scenarios. This study provides a data-efficient and physically consistent solution for broadband 3D acoustic field reconstruction.

Xianwu Ke, Xiaotian Shen, Tiechuan Li et al.

Droplet-based microfluidics have drawn much attention in recent years and have been successfully applied in biochemical analysis, material synthesis, and biomedical engineering. Precise and flexible manipulations of droplets are the basis of various applications. Numerous techniques have been introduced to achieve on-demand control of droplets, including electric, magnetic, acoustic, optical, and thermal methods. Among these, the combination of acoustics and microfluidics (termed acoustofluidics) has shown great potential and advantages in droplet manipulation as it is non-invasive, high-precision, low-cost, easily integrated, and biocompatible. Here, we summarize recent works on acoustofluidic manipulations of droplet-based microfluidics. This paper is structured into three main sections. First, the commonly used acoustic devices in acoustofluidics and their working principles are introduced. Such acoustic devices include interdigital transducers, Lamb wave resonators, and bulk acoustic resonators, and generate acoustic waves with frequencies ranging from kilohertz to gigahertz. Second, the forces and effects involved in droplet manipulations using acoustofluidics are analyzed. Third, the manipulation processes of droplet microfluidics using various acoustofluidic techniques are summarized and compared with other methods, including droplet generation, mixing, splitting, fusion, sorting, transportation, and internal particle patterning. Finally, current challenges and future prospects for acoustofluidic manipulation techniques for droplet-based microfluidics are discussed.

Fuyin Ma

Due to the sub-wavelength structural characteristics and excellent wave regulation ability, metamaterials have important application value regulating acoustic and elastic waves. After more than 20 years of continuous development, the achievements of acoustics and elastic metamaterials have become very abundant. Especially in recent years, with the increasingly close integration with engineering application scenarios, metamaterials have shown important application value in many fields, such as aviation, aerospace, ships, rail vehicles, automobiles, home appliances, and architecture. Therefore, in order to promote the development of metamaterials in applications, we have organized three special issues, attracted the attention of many scholars, and received more than 30 submissions. To provide better guidance for the subsequent application research of metamaterials, we will briefly introduce the main breakthroughs in metamaterial applications at present, including sound absorption, sound insulation, vibration absorption, vibration isolation, noise reduction with ventilation, and acoustic detection and communication.

S. Habibi

The acoustic design of multipurpose halls requires a careful balance between speech intelligibility and music clarity, necessitating precise control of reverberation time (RT), sound distribution, and clarity. This study examines the transformation of a multipurpose hall through architectural modifications that enhance performance for both speech and music. By integrating Sabine’s equation with parametric surface optimization, the study evaluates key acoustic metrics, including RT, initial-time delay gap (ITDG), clarity index (C80), and spatial perception factors such as eye position and viewing angle optimization. The results confirm that targeted geometric and material interventions effectively optimize acoustics, reducing RT for speech while maintaining adequate reverberation for musical performances. Unlike previous studies that focus primarily on either architectural design or acoustic engineering, this research demonstrates an integrated framework bridging both disciplines. While methodologies such as ODEON and CATT-Acoustic are widely used in room acoustics research, this study emphasizes a scalable and accessible approach tailored for architectural applications. By addressing the interplay between spatial design and acoustic performance, the findings contribute to a broader understanding of adaptive acoustic environments in multipurpose venues.

Yu Yicheng, Hopkins Carl

Multilayer elements, such as sandwich panels, are often used to form the roof of a building or car; hence validated prediction models are needed to determine the sound radiated by them during rainfall. To calculate the radiation efficiency of a sandwich panel formed from two plates and a porous material, the Finite Transfer Matrix Method (FTMM) has been used with an order-reduced integral equation and an additional term to account for nearfield radiation because, in comparison with homogeneous plates, sandwich panels tend to have high damping. Transfer mobility measurements on the sandwich panel showed that vibrational energy was concentrated near the point of excitation due to the panel being highly damped, and confirmed the validity of the limp porous material model for the foam that was used as the porous material. Experimental validation of the prediction models used artificial rain with drops impacting at approximately terminal velocity. This demonstrated that it was necessary to include the effect of nearfield radiation in the overall radiation efficiency. An assessment of existing empirical and semi-empirical models for the time-dependent force applied by liquid water drops showed that for this application of artificial rain in the laboratory it was reasonable to assume a dry surface when predicting the structure-borne sound power input.

Lincke Dorothea, Kawai Claudia, Pieren Reto

Auralization of outdoor sound propagation has become an important tool for studying noise perception in the contexts of aircraft, wind farm, and drone noise. To achieve high realism, these auralizations consider amplitude fluctuations caused by atmospheric turbulence. In a recent publication, a semi-empirical model was introduced which is applicable to relatively long outdoor sound propagation such as aircraft and wind farm noise, as it considers the saturation effect for amplitude fluctuations in the partially-saturated regime. This article presents a study applying the semi-empirical model for investigating the impact of turbulence-induced amplitude fluctuations on annoyance in auralized aircraft flyovers. For this, two 2-alternative-forced-choice listening experiments were conducted in a controlled laboratory setting: the first tested whether participants could reliably detect audible differences between aircraft flyovers under different meteorological conditions; the second assessed which condition was perceived as more annoying. The results show that strong differences in meteorological conditions and the respective atmospheric turbulence can lead to salient audible differences. Relative annoyance ratings tend to increase with stronger atmospheric turbulence. Further, the data suggest that amplitude fluctuations can interact with other characteristics of aircraft noise such as fan tones and alter the perceptual impact of these characteristics. Therefore, the study highlights the importance of modeling turbulence-induced amplitude fluctuations in realistic aircraft auralizations, and presumably also wind farm and drone noise auralization, as the perceptual impression can be affected in several ways.

Couineaux Audrey, Ablitzer Frédéric, Gautier François

The cristal Baschet is a musical instrument created during the 50’s by Bernard and Francois Baschet. It is composed of a large number of glass rods arranged in a chromatic scale. Frictional interaction between wet fingers and glass rods triggers self-sustaining vibrations of the resonator, assembly of metal parts and glass rod, which are transmitted to acoustic radiators. The instrument can be equipped with auxiliary elements to modify its timbre. In particular, long thin metal rods called whiskers are commonly added. They act as additional resonators that induce sound enrichment by emphasizing certain higher harmonics. As the manufacturing process of this instrument relies on empirical knowledge, the way whiskers should be tuned to achieve the desired effect is not well known. In this study, modal experimental analysis and numerical modeling are used to understand the dynamic behavior of whiskers and their interaction with the rest of the instrument. First, the simplified structure which is composed of one resonator and one whisker is studied. Experimental measurements are compared with time-domain simulations to gain insight into the role of whiskers and propose tuning guidelines. It is demonstrated that a slow oscillation of the whisker induces a modulation of some specific modes for which the longitudinal and flexural motions are strongly coupled. Such modulation of high order spectral components of the cristal’s sound induces an unusual and characteristic timbre.

Apalowo Rilwan Kayode, Abas Aizat, Chronopoulos Dimitrios

This study investigates the effects of tensile pre-stress, compressive pre-stress, and surface pressure loads on the vibroacoustic behavior of laminated composite panels using a wave-based Statistical Energy Analysis (SEA) framework. A Wave Finite Element (WFE) method is used to compute wave dispersion, which informs the calculation of modal density, acoustic radiation efficiency, and sound transmission loss (STL). The numerical framework is validated against benchmark experimental and numerical results, with maximum discrepancies below 10%. Results reveal that tensile pre-stress decreases dispersion and modal density while shifting the coincidence frequency downward – from 15.2 kHz (0 N) to 5.1 kHz (100 N). In contrast, compressive pre-stress increases modal density and raises the coincidence frequency, reaching 108.5 kHz at 400 N. Surface pressure primarily affects low-frequency dynamics, increasing dispersion and reducing modal density, with STL coincidence frequency shifting from 12 kHz (0.6 GPa) to 20 kHz (0 GPa). Under combined loading, the dynamic response is intermediate, with pre-stress modulating the out-of-plane stiffening effect of pressure. These results offer critical insight for tailoring vibroacoustic performance in lightweight composite structures, particularly in aerospace and transport systems subjected to operational loading.

Ana Arauzo

This lecture presents an overview of the basic concepts and fundamentals of Engineering Materials within the framework of accelerator applications. After a short introduction, main concepts relative to the structure of matter are reviewed, like crystalline structures, defects and dislocations, phase diagrams and transformations. The microscopic description is correlated with physical properties of materials, focusing in metallurgical aspects like deformation and strengthening. Main groups of materials are addressed and described, namely, metals and alloys, ceramics, polymers, composite materials, and advanced materials, where brush-strokes of tangible applications in particle accelerators and detectors are given. Deterioration aspects of materials are also presented, like corrosion in metals and degradation in plastics.

I. Melnyk

The psychological impact of the war in Ukraine has created an urgent and substantial need for effective mental health interventions, particularly psychotherapy. As offline therapy often requires deep engagement, the quality of the physical environment becomes paramount. This article addresses the critical issue of acoustic comfort in psychotherapy spaces, an essential factor for ensuring patient confidentiality, effective communication, and a conducive therapeutic atmosphere, yet one for which specific standards are currently lacking in Ukraine. Drawing on a review of the literature on post-war mental health needs and the influence of environmental acoustics on well-being and communication, combined with professional experience in engineering acoustics, this article identifies key acoustic parameters necessary for effective therapeutic settings. These include adequate sound insulation to guarantee privacy, controlled reverberation time for speech intelligibility, minimization of intrusive background noise from building systems, and consideration of electroacoustic methods to support individuals with hearing impairments. The analysis highlights that, while there are broader concepts of acoustic design, meeting the specific needs of psychotherapy requires adherence to fundamental principles of acoustic engineering. The article argues that the absence of acoustic standards customised for therapy spaces in Ukraine represents a significant challenge to providing high-quality mental healthcare. It concludes that establishing clear and measurable acoustic criteria is a vital infrastructure to support psychological recovery and lays the groundwork for developing such essential standards.

Shwetha A B

This research explores AcouWrite, a novel mobile handwriting recognition system leveraging acoustics and active acoustic sensing technologies. While conventional handwriting recognition systemstraditionally rely on visual orinertial sensors, these approaches often prove unsuitable in scenarios demanding privacy or hands-free interaction. AcouWrite innovatively employs short-time differential Channel Impulse Response (st-dCIR) combined with a Convolutional Neural Network-Gated Recurrent Unit (CNN-GRU) model to enable real-time, off-screen handwriting recognition. This paper provides an exhaustive account of AcouWrite's architecture, comprehensively compares it to signal- and gesture-based systems, and rigorously analyzes its accuracy, adaptability, and robustness across various devices. The conclusion presents an overview of existing challenges and potential future advancements within the burgeoning field of acoustic-based human-computer interaction.

C. S. Sumesh, M. V. Roshan, S. S et al.

Maroua Dahmani, Ilyas Antraoui, A. Khettabi et al.

This study investigates the complex dynamics of waveguides by analyzing periodic structures incorporating closed resonators. We have examined a specific configuration composed of N single resonators, with and without geometrical defects in the main waveguide. The approach adopted is based on the transfer matrix method, enabling detailed analysis of the defect impact and complete characterization of low-frequency resonance phenomena. Under optimal conditions, the structural periodicity of the system leads to the creation of an acoustic band gap where the wave cannot propagate in the structure. Moreover, the presence of a defect has a significant effect on the appearance of localized modes in the acoustic band gap. Increasing the defect guide leads to the generation of multiple resonant modes with high acoustic transmittance. The position of these modes was well controlled by varying the length of the defect. These results are very useful in the field of acoustics, and pave the way for innovative applications such as acoustic filters and high-resolution sensors. This study thus offers an innovative framework for exploiting the effects of defects in waveguide systems, contributing to the evolution of modern acoustic technologies.