Hasil untuk "Acoustics in engineering. Acoustical engineering"

Monsalve Jorge M., Schenk Hermann A. G.

The acoustic fields within the microchannels of an in-plane electrostatic ultrasound transducer are analysed in this work by means of the Low Reduced Frequency (LRF) approximation of the Navier–Stokes equations. This device is composed primarily of two kinds of structures that can be described in rectangular coordinates – a prismatic slit and a cavity with curved walls –, for which a solution of the LRF equations is presented. The interaction between these two elements in an actual device is solved by an approximate model whereby the propagation modes are transmitted from one component to the other without energy losses. The solution of the LRF equations in the isolated components offered results that were in good agreement with equivalent finite-element simulations of the Full Linearised Navier–Stokes (FLNS) equations, whereas the approximate model of the complete structure slightly overestimates the output pressure in comparison to the corresponding simulation. The predictions of the analytic and finite-element models of the device were compared against an actual measurement, finding an approximate correspondence, although certain effects remain to be predicted by a more accurate analysis of the radiation pattern of the device.

Satoshi Hoshika, Takahiro Iwami, Akira Omoto

This study proposes a framework for incorporating wavenumber-domain acoustic reflection coefficients into sound field analysis to characterize direction-dependent material reflection and scattering phenomena. The reflection coefficient is defined as the amplitude ratio between incident and reflected waves for each propagation direction and is estimated from spatial Fourier transforms of the incident and reflected sound fields. The resulting wavenumber-domain reflection coefficients are converted into an acoustic admittance representation that is directly compatible with numerical methods such as the Boundary Element Method (BEM), enabling simulation of reflections beyond simple specular components. Unlike conventional extended reaction models, the proposed approach avoids explicit modeling of the material interior. This significantly reduces computational cost while allowing direct use of measured data, empirical models, or user-defined directional reflection characteristics. The validity of the proposed formulation was previously demonstrated by the authors through two-dimensional sound field simulations, in which accurate reproduction of direction-dependent reflection behavior was confirmed. In the present work, the framework is extended to three-dimensional analysis, demonstrating its applicability to more realistic and complex acoustic environments. The proposed approach provides a practical and flexible tool for simulating direction-dependent acoustic reflections and scattering, with potential applications in architectural acoustics, material characterization, and noise control.

K. Mahesh, S. K. Ranjith, R. Mini

Carlos Ezio Garciamendez-Mijares, David S Rendon Ruiz, Xiao Kuang et al.

Bioprinting has facilitated tissue engineering by enabling the fabrication of biologically and physiologically relevant 3D constructs. However, conventional bioprinting techniques often lack precise control over the spatial organization of cells within bioprinted structures. Acoustics, on the other hand, offers a powerful tool for non‐contact, label‐free, high‐precision cell manipulation but is inherently limited in its ability to create complex volumetric architectures. The integration of these two technologies, termed acoustic bioprinting, holds significant promise for advancing biofabrication. In this review, the synergistic potential of acoustics in enhancing three primary bioprinting modalities—droplet, light‐polymerization, and extrusion—is analyzed. The ways in which acoustic fields can improve cell patterning, alignment, and bioink‐manipulation—leading to more biomimetic constructs with enhanced physiological properties—are dicussed. Additionally, novel ultrasound‐polymerization‐based bioprinting technologies that leverage cavitation, sono‐thermal effects, and liposome‐mediated polymerization to enable deep penetration biofabrication, expanding the scope of bioprinting beyond conventional methods, are explored. By leveraging the strengths of both bioprinting and acoustics, this review highlights emerging strategies that can shape the next generation of biofabrication, offering innovative solutions for tissue engineering and regenerative medicine.

A. Chen, Yifei Xia, Zhao Chen et al.

High‐precision dynamic sound manipulation remains a fundamental challenge in acoustics, crucial for diverse applications. Phased arrays (PAs), widely applied for real‐time sound control, are limited in resolution and complexity. Recently‐emerged acoustic metamaterials (AMs) significantly simplify high‐precision wavefront engineering, yet remain passive with fixed functionalities or have complicated active control systems to enhance resolution. To break through the above limitations, here a metamaterial‐empowered PA (MPA) that achieves dynamic sound manipulation with a diffraction limit‐approaching resolution using only wavelength‐scale transducers is proposed and experimentally demonstrated. It is analytically proven that acoustically shrinking each element by designed AMs substantially eliminates the aliasing effects and enhances the spatial precision of sound manipulation. Thanks to the uniformity of metamaterial units attached one‐by‐one to PA elements, the produced sound field can be reformed in real time without structural modifications. The unique performance of the MPA is showcased via two typical examples of high‐quality programmable focusing and real‐time imaging with subwavelength resolution, which is beyond attainable relying solely on current PAs or AMs. The proposed mechanism offers an integrated and low‐cost solution to the long‐standing challenge of dynamic and high‐precision wave manipulation and has far‐reaching impacts from biomedical imaging to nondestructive evaluation.

Jiaxin Zhong, Jun Ji, X. Xia et al.

Significance Recent advancements in digital signal processing and loudspeaker array design have enabled us to experience immersive spatial audio in virtual/augmented/extended reality environments in our daily lives. However, further development in audio engineering is impeded by physical constraints stemming from the diffraction of long-wavelength audio waves. This study introduces an approach to address this issue by showcasing the creation of ultrabroadband (125 Hz to 4 kHz) and highly localized remote audio spots, referred to as audible enclaves. By marrying local acoustic nonlinearity with inaudible self-bending ultrasonic beams, the proposed technique overcomes the physical limits in linear acoustics, paving the way for possibilities in future audio engineering.

Jianhua Lin, Weike Li, Rengui Bi et al.

Rainbow trapping and the frequency separation of elastic waves in topological phononic metamaterials hold significant promise for information processing. However, a shared acoustic channel for frequency separation complicates acoustics signal processing. In this paper, we constructed a unit cell by etching curved slots into an aluminum plate and analyzed its topological properties using two-dimensional polarization techniques. By adjusting the structural parameters and creating three gradient structures, we achieved rainbow trapping and frequency separation across a dual frequency band. This allows waves of different frequencies to be split and directed to various locations, while other frequencies can be output from different ports. This study offers an effective approach for separating and capturing acoustic signals, with potential applications in engineering and technology.

E. Kaselouris, Vassilis M. Dimitriou

The integration of Finite Element Method (FEM) simulations with laser-based techniques has significantly advanced acoustic research by enhancing wave measurement, analysis, and prediction in complex solid media. This review examines the role of the FEM in laser-based acoustics for wave propagation, defect detection, biomedical diagnostics, and engineering applications. FEM models simulate ultrasonic wave generation and propagation in single-layer and multilayered structures, while laser-based experimental techniques provide high-resolution validation, improving modeling accuracy. The synergy between laser-generated ultrasonic waves and FEM simulations enhances defect detection and material integrity assessment, making them invaluable for non-destructive evaluation. In biomedical applications, the FEM aids in tissue characterization and disease detection, while in engineering, its integration with laser-based methods contributes to noise reduction and vibration control. Furthermore, this review provides a comprehensive synthesis of FEM simulations and experimental validation while also highlighting the emerging role of artificial intelligence and machine learning in optimizing FEM models and improving computational efficiency, which has not been addressed in previous studies. Key advancements, challenges, and future research directions in laser-based acoustic applications are discussed.

Middleton Michael, Murphy Damian T., Savioja Lauri

A method of solving the 2D acoustic wave equation using Fourier Neural Operator (FNO) networks is presented. Various scenarios including wave superposition are considered, including the modelling of multiple simultaneous sound sources, reflections from domain boundaries and diffraction from randomly-positioned and sized rectangular objects. Training, testing and ground-truth data is produced using the acoustic Finite-Difference Time-Domain (FDTD) method. FNO is selected as the neural architecture as the network architecture requires relatively little memory compared to some other operator network designs. The number of training epochs and the size of training datasets were chosen to be small to test the convergence properties of FNO in challenging learning conditions. FNO networks are shown to be time-efficient means of simulating wave propagation in a 2D domain compared to FDTD, operating 25 × faster in some cases. Furthermore, the FNO network is demonstrated as an effective means of data compression, storing a 24.4 GB training dataset as a 15.5 MB set of network weights.

Bucur Voichita

The aim of this article is to describe the development of the ultrasonic non-destructive velocity method for applications in Wood Science and Forestry. A key question addressed was the mechanical characterisation of wood on an increment core of 5 mm diameter bored from a standing tree. Theoretical considerations were studied for the characterisation of wood as an orthotropic solid. Acoustic invariants were introduced to characterise wood anisotropy. Wave propagation phenomena were related to macroscopic and microscopic particularities of wood structure. The mechanical characteristics of wood species for violins have been thoroughly studied. The detection of wood degradation by biological agents producing decay (fungi, bacteria), using the ultrasonic velocity method combined with X ray densitometry was studied. The ultrasonic velocity method was also applied to quality assessment of some wood-based composites. For applications in Forestry, it was demonstrated that on increment cores of 5 mm diameter bored from standing trees, it was possible to determine three stiffnesses and three shear moduli of wood and to assess the mechanical wood quality of standing trees. Other factors (the slope of the grain, pruning) affecting the quality of wood of standing trees were detected with the velocity method. In Forestry, seeds are important products. The capacity of the germinability of acorns was detected with the ultrasonic velocity method.

Fritz Claudia, Stoppani George, Igartua Unai et al.

Violin makers and acousticians have long sought correlations between sound qualities, construction parameters and vibroacoustic measurements. This is challenging for three main reasons: it is difficult to build violins reliably enough to ensure that the change in the sound is only a result of the intended change of construction parameters; no clear link has been found so far between measurements and perceived qualities; and when listening to violins being played, differences tend to be smoothed out by the players who adapt very quickly. Therefore, while we have previously preferred using players in our experiments to maximise ecological validity and account for the complexity of the interaction between the player and the instrument, in this study we test whether other methods that reduce the player's influence, though more artificial, may be useful for exploring the impact of certain construction parameters on the sound. In the context of a set of violins built with controlled thickness variations in their plates, we conducted two listening tests, based on real recordings of a player and a bowing machine, along with synthesised sounds created from an excerpt recorded with piezo sensors by convolution with radiation measurements in an anechoic chamber. The hybrid synthesis was found to be the most effective of the three in highlighting instrument differences, capturing properties perceived in the actual instruments, and correlating with radiation measurements.

Türüdü Soner, Koelewijn Thomas, Araiza-Illan Gloria et al.

Introduction: To investigate the effects of frequently used variations of the Digits-in-Noise (DIN) test on speech reception threshold (SRT) for onsite and online implementations. Methods: We tested various DIN test implementations in a within-subject design on 30 normal-hearing adults onsite, with 22 of them also online. We varied three parameters: (1) sound presentation, diotic or antiphasic; (2) starting signal-to-noise ratio (SNR), 0 or −16 dB; and (3) mixing method, with fixed presentation level of the speech, the noise, or the speech and noise mix (tested onsite only). Results: Antiphasic presentation yielded significantly lower DIN SRTs than diotic by around 6 dB. The effects of starting SNR and mixing method were significant but small, around 1−2 dB. These effects seemed more pronounced with antiphasic presentation. Overall, onsite and online DIN test results were comparable, with the largest observed difference being 1.30 dB. Conclusion: The selection of diotic or antiphasic sound presentation seems important, and antiphasic presentation may result in a more sensitive test. In contrast, the effects of the other parameters were small. The comparable onsite and online outcomes indicate that online testing via the internet could be a viable option for making the DIN test available to large populations.

Fernando Ayach, Vitor Lameirão, Raul Leão et al.

Proto-personas are commonly used during early-stage Product Discovery, such as Lean Inception, to guide product definition and stakeholder alignment. However, the manual creation of proto-personas is often time-consuming, cognitively demanding, and prone to bias. In this paper, we propose and empirically investigate a prompt engineering-based approach to generate proto-personas with the support of Generative AI (GenAI). Our goal is to evaluate the approach in terms of efficiency, effectiveness, user acceptance, and the empathy elicited by the generated personas. We conducted a case study with 19 participants embedded in a real Lean Inception, employing a qualitative and quantitative methods design. The results reveal the approach's efficiency by reducing time and effort and improving the quality and reusability of personas in later discovery phases, such as Minimum Viable Product (MVP) scoping and feature refinement. While acceptance was generally high, especially regarding perceived usefulness and ease of use, participants noted limitations related to generalization and domain specificity. Furthermore, although cognitive empathy was strongly supported, affective and behavioral empathy varied significantly across participants. These results contribute novel empirical evidence on how GenAI can be effectively integrated into software Product Discovery practices, while also identifying key challenges to be addressed in future iterations of such hybrid design processes.

Alexandra Mazak-Huemer, Christian Huemer, Michael Vierhauser et al.

With the increasing significance of Research, Technology, and Innovation (RTI) policies in recent years, the demand for detailed information about the performance of these sectors has surged. Many of the current tools are limited in their application purpose. To address these issues, we introduce a requirements engineering process to identify stakeholders and elicitate requirements to derive a system architecture, for a web-based interactive and open-access RTI system monitoring tool. Based on several core modules, we introduce a multi-tier software architecture of how such a tool is generally implemented from the perspective of software engineers. A cornerstone of this architecture is the user-facing dashboard module. We describe in detail the requirements for this module and additionally illustrate these requirements with the real example of the Austrian RTI Monitor.

Jannatul Bushra, Md Habibor Rahman, Mohammed Shafae et al.

Reverse engineering can be used to derive a 3D model of an existing physical part when such a model is not readily available. For parts that will be fabricated with subtractive and formative manufacturing processes, existing reverse engineering techniques can be readily applied, but parts produced with additive manufacturing can present new challenges due to the high level of process-induced distortions and unique part attributes. This paper introduces an integrated 3D scanning and process simulation data-driven framework to minimize distortions of reverse-engineered additively manufactured components. This framework employs iterative finite element simulations to predict geometric distortions to minimize errors between the predicted and measured geometrical deviations of the key dimensional characteristics of the part. The effectiveness of this approach is then demonstrated by reverse engineering two Inconel-718 components manufactured using laser powder bed fusion additive manufacturing. This paper presents a remanufacturing process that combines reverse engineering and additive manufacturing, leveraging geometric feature-based part compensation through process simulation. Our approach can generate both compensated STL and parametric CAD models, eliminating laborious experimentation during reverse engineering. We evaluate the merits of STL-based and CAD-based approaches by quantifying the errors induced at the different steps of the proposed approach and analyzing the influence of varying part geometries. Using the proposed CAD-based method, the average absolute percent error between simulation-predicted distorted dimensions and actual measured dimensions of the manufactured parts was 0.087%, with better accuracy than the STL-based method.

Bilkent Samsurya

Accurate sound propagation simulation is essential for delivering immersive experiences in virtual applications, yet industry methods for acoustic modeling often do not account for the full breadth of acoustic wave phenomena. This paper proposes a novel two-dimensional (2D) finite-difference time-domain (FDTD) framework that simulates sound propagation as a wave-based model in Unreal Engine, with an emphasis on capturing lower frequency wave phenomena, embedding occlusion, diffraction, reflection and interference in generated impulse responses. The process begins by discretizing the scene geometry into a 2D grid via a top-down projection from which obstacle masks and boundary conditions are derived. A Python-based FDTD solver injects a sine sweep at a source position, and virtual quadraphonic microphone arrays record pressure field responses at pre-defined listener positions. De-convolution of the pressure responses yields multi-channel impulse responses that retain spatial directionality which are then integrated into Unreal Engine's audio pipeline for dynamic playback. Benchmark tests confirm agreement with analytical expectations, and the paper outlines hybrid extensions aimed at commercial viability.

Allysson Allex Araújo, Marcos Kalinowski, Matheus Paixao et al.

[Background] Emotional Intelligence (EI) can impact Software Engineering (SE) outcomes through improved team communication, conflict resolution, and stress management. SE workers face increasing pressure to develop both technical and interpersonal skills, as modern software development emphasizes collaborative work and complex team interactions. Despite EI's documented importance in professional practice, SE education continues to prioritize technical knowledge over emotional and social competencies. [Objective] This paper analyzes SE students' self-perceptions of their EI after a two-month cooperative learning project, using Mayer and Salovey's four-ability model to examine how students handle emotions in collaborative development. [Method] We conducted a case study with 29 SE students organized into four squads within a project-based learning course, collecting data through questionnaires and focus groups that included brainwriting and sharing circles, then analyzing the data using descriptive statistics and open coding. [Results] Students demonstrated stronger abilities in managing their own emotions compared to interpreting others' emotional states. Despite limited formal EI training, they developed informal strategies for emotional management, including structured planning and peer support networks, which they connected to improved productivity and conflict resolution. [Conclusion] This study shows how SE students perceive EI in a collaborative learning context and provides evidence-based insights into the important role of emotional competencies in SE education.

Manuj Yadav, Jungsoo Kim, Valtteri Hongisto et al.

Open-plan offices are well-known to be adversely affected by acoustic issues. This study aims to model acoustic dissatisfaction using measurements of room acoustics, sound environment during occupancy, and occupant surveys (n = 349) in 28 offices representing a diverse range of workplace parameters. As latent factors, the contribution of $\textit{lack of privacy}$ (LackPriv) was 25% higher than $\textit{noise disturbance}$ (NseDstrb) in predicting $\textit{acoustic dissatisfaction}$ (AcDsat). Room acoustic metrics based on sound pressure level (SPL) decay of speech ($L_{\text{p,A,s,4m}}$ and $r_{\text{C}}$) were better in predicting these factors than distraction distance ($r_{\text{D}}$) based on speech transmission index. This contradicts previous findings, and the trends for SPL-based metrics in predicting AcDsat and LackPriv go against expectations based on ISO 3382-3. For sound during occupation, $L_{\text{A,90}}$ and psychoacoustic loudness ($N_{\text{90}}$) predicted AcDsat, and a SPL fluctuation metric ($M_{\text{A,eq}}$) predicted LackPriv. However, these metrics were weaker predictors than ISO 3382-3 metrics. Medium-sized offices exhibited higher dissatisfaction than larger ($\geq$50 occupants) offices. Dissatisfaction varied substantially across parameters including ceiling heights, number of workstations, and years of work, but not between offices with fixed seating compared to more flexible and activity-based working configurations. Overall, these findings highlight the complexities in characterizing occupants' perceptions using instrumental acoustic measurements.

It is with great pleasure and a sense of accomplishment that we present the proceedings of the 2024 3rd International Conference on Acoustics, Fluid Mechanics and Engineering (AFME 2024). This event has once again brought together leading scholars, researchers, and industry experts from around the globe to share their latest findings, discuss emerging trends, and foster collaborations in the fields of acoustics, fluid mechanics, and engineering. The conference attracted about 100 experts, scholars, researchers, enterprise representatives and relevant personnel from all over the world, showing wide international influence. They shared the latest research results, exchanged technical experiences and explored cooperation opportunities at the event, jointly fostering research and development in acoustics and fluid mechanics engineering. The conference agenda mainly included keynote speech, oral presentation, poster presentation, academic discussion, among others, all of which together fostered an environment conducive to understanding academic trends, broadening research horizons, strengthening academic discourse, as well as promoting the industrialization of research outcomes. During the event, Professor Liang Yu from Northwestern Polytechnical University presented a report titled “Advanced Acoustic Testing Techniques for Aerospace Machinery Equipment,” showcasing cutting-edge achievements in the field of acoustic testing for aerospace machinery. Subsequently, Associate Professor Pan Gao from Shanghai Maritime University provided attendees with in-depth insights into numerical simulations of rotor sail aerodynamic performance. Last but not the least, Researcher Haiqiang Niu from the Institute of Acoustics of the Chinese Academy of Sciences showcased his research which introduces machine learning techniques into the field of underwater acoustic source localization. An impressive array of speakers delivered insightful and inspiring presentations on different topics. The proceedings of AFME 2024 encompasses a broad range of topics that encapsulate the essence of acoustics, fluid mechanics, and engineering. These include, but are not limited to, Acoustic Materials, Ultrasonics, Hydrodynamic Acoustics, Nonlinear Mechanical Wave Dynamics, Fluid Sound Radiation, Vibration and Noise Analysis and Control, Gas Dynamics, Engineering Fluid Mechanics, etc. Each paper, after meticulous peer-review by a panel of esteemed experts, has been selected for inclusion based on its novelty, completeness, and potential impact in the fields. The authors, hailing from prestigious universities, research institutions, and industry worldwide, have presented their findings in a clear and concise manner, making this collection a valuable resource for scholars, students, and practitioners alike. In the final foreword, we would like to thank all the speakers, authors, reviewers, and all the people involved in the conference. We also appreciate the members of technical program committee for giving such an opportunity for all of us to share scientific ideas and new developments at the conference. Last but not the least, our special acknowledgement also goes to the editors of IOP Press-Journal of Physics: Conference Series, for their preparation and assistance in publishing this paper volume. The Committee of AFME 2024

E. Riva, Federico Bellinzoni, Francesco Braghin

Extreme localization in engineered lattices is paramount for wave manipulation and robust signal guidance. Yet, an experimental demonstration of flat-band-induced compact localized states (CLS) and boundary modes in acoustic Kagome lattices has remained elusive, a gap we address herein. Compact localized states populate singular dispersion bands characterized by band crossing, where a quadratic and a flat dispersion coalesce into a singularity. The strength of this singularity is quantified using the Hilbert-Schmidt quantum distance, providing a bulk-boundary correspondence. This condition gives rise to states extremely localized in the plane and protected by dispersion flatness, characterized by broadband and sustained confinement over time. The analysis is extended to a system of coupled acoustic waveguides, where sound propagates out-of-plane within tightly localized in-plane sites, either at the boundaries or within the interior of the lattice. This framework opens avenues for the manipulation and transport of sound waves, with potential applications in communication, signal processing, and sound isolation, expanding the reach of flat-band lattice physics within acoustics. Kagome lattices have become a popular platform to investigate exotic electronic and optical phenomena but they can also be adapted to mechanical and acoustic systems. Here, the authors numerically and experimentally demonstrate flat band-induced compact localized states in an acoustic 2D Kagome lattice, which have potential applications for acoustic sensing and transport.