Hasil untuk "Acoustics in engineering. Acoustical engineering"

Ducasse Éric, Rodriguez Samuel, Bonnet Marc

For the ultrasonic inspection of bounded elastic structures, finite-duration imaging functions are derived in the Fourier–Laplace domain, where efficient computational tools exist for solving problems in linear elasticity. The signals involved are exponentially windowed, so that early reflections are taken into account more strongly than later ones in the imaging methodology. Applying classical approaches to the general case of anisotropic elasticity, we express the Fréchet derivatives of the relevant data-misfit functional with respect to arbitrary perturbations of the mass density and stiffnesses in terms of forward and adjoint solutions. Their definitions incorporate the exponentially decaying weighting. The proposed finite-duration imaging functions are then defined on that basis. As some areas of the structure are less insonified than others, it is necessary to define normalized imaging functions to compensate for these variations. Our approach in particular aims to overcome the difficulty of dealing with bounded domains containing defects not located in direct line of sight from the transducers and measured signals of long duration. In this preliminary and methodological work, we demonstate the potential of the proposed approach on a two-dimensional test case featuring the imaging of mass and elastic stiffness variations in a region of a bounded isotropic medium that is not directly visible from the transducers. The results show that the early-reverberation imaging (ERI) method allows for mapping anomalies in masked regions of a structure with reasonable computational efforts.

Oleksandr Kosenkov, Ehsan Zabardast, Jannik Fischbach et al.

Implementing privacy by design (PbD) according to the General Data Protection Regulation (GDPR) is met with a growing number of requirements engineering (RE) approaches. However, the question of which RE method for PbD fits best the goals of organisations remains a challenge. We report our endeavor to close this gap by synthesizing a goal-centric approach for PbD methods assessment. We used literature review, interviews, and validation with practitioners to achieve the goal of our study. As practitioners do not approach PbD systematically, we suggest that RE methods for PbD should be assessed against organisational goals, rather than process characteristics only. We hope that, when further developed, the goal-centric approach could support the development, selection, and tailoring of RE practices for PbD.

Ghiringhelli Elisa, Lasaygues Philippe, Guivier-Curien Carine et al.

Pulsed focused ultrasound (p-FUS) are gaining interest across a range of applications, such as regenerative medicine, neurostimulation and targeted drug delivery, offering a non-invasive therapeutic approach. In order to gain insight into the hydrodynamic effects potentially induced by p-FUS in biological tissues, the present acoustofluidic study investigates the ability of focused ultrasound to generate acoustic streaming in a viscous fluid confined in a microchannel. Through micro-particle image velocimetry (μPIV) measurements, it analyses the flow patterns induced by p-FUS in a rectangular cross-section microchannel, corresponding to half of the ultrasonic wavelength. The analysis confirmed good repeatability across replicates, despite minor variations introduced by manual assembly. It is shown that the flow patterns reach the equilibrium within seconds and that the average streaming velocity varies quadratically with the duty cycle characterizing p-FUS. Moreover, the results indicate that the streaming velocity magnitude depends on the amount of acoustic energy delivered to the channel. Interestingly, the induced flow exhibits a strongly three-dimensional structure, revealing spatial dynamics that, to our knowledge, have not been previously observed in microscale acoustic streaming studies. These results lay the foundation for understanding the interaction of p-FUS with a confined fluid at the microscale, opening new avenues for investigating more complex networks and porous media representing biological tissues.

Szwarcberg Nathan, Colinot Tom, Vergez Christophe et al.

The Transfer Matrix Method is a practical approach for modeling plane wave propagation in one-dimensional waveguides. Its simplicity makes it especially attractive for accounting for viscothermal losses, enabling realistic simulations of complex waveguides such as wind instruments. Another strength of this method lies in its fully analytical formulation of wave propagation. Modal parameters naturally arise as by-products of the model, obtained by numerically solving analytical expressions. In this work, the analytical potential of the method is extended by deriving the sensitivity of modal parameters to changes in the geometry of the resonator. These analytical gradients are applied in the context of wind instrument design. A simplified model of a soprano saxophone is used to investigate how octave harmonicity can be optimized through small geometric adjustments. The proposed approach enables predictive adjustments of geometry and offers valuable insight for both sound synthesis and instrument making.

Jamois Alexis, Dragna Didier, Zieliński Tomasz G. et al.

Prediction of the acoustic performance of 3D printed materials is investigated at normal and grazing incidence. A direct numerical (microscopic) simulation that solves the full set of Navier–Stokes equations is used as a reference. It is compared with a macroscopic approach in which the material is represented by an equivalent fluid. The materials have a periodic microstructure, consisting either of a single network of spherical or cubic cavities connected by cylindrical channels or of a double-nested network. The samples are printed using the stereolithography technique and are tested using an impedance tube and a duct test bench. For single network geometries, the results of sound absorption at normal and grazing incidence predicted using the equivalent fluid approach are in good agreement with those obtained by the microscopic approach. Comparisons with impedance tube measurements confirm that both approaches can accurately predict the absorption coefficient of the samples. For the in-duct liner configuration, the transmission loss measurements and predictions show similar evolution with frequency change, despite the discrepancy in amplitude. For the double network geometry, the equivalent fluid approach cannot exactly reproduce the results obtained with the direct numerical simulation. Finally, while the predictions with the microscopic approach provide a good match with the impedance tube measurements, only a poor agreement is obtained using the duct testing bench.

Yang Shuai, Yin Jia-Hao, Zhu Xiao-Jing et al.

This study investigates the properties of band gaps of circular core filling fractal phononic crystals (CCFFPCs), specifically focusing on the impact of different filling positions on the frequency of band gaps. The research demonstrates that core filling at the central positions significantly influences the formation and widening of low-frequency band gaps, while filling at corner edges predominantly affects mid-frequency band gaps, and filling at edge centers effectively opens and broadens high-frequency band gaps. These results reveal the relationship between filling positions and band gap tuning, providing a theoretical foundation for precise band gap control across a full frequency range. Moreover, this study is the first to systematically clarify the impact of core filling positions on band gap frequencies, expanding the design strategies for band gaps in fractal phononic crystals. Furthermore, this study employs genetic algorithm optimization to achieve the maximum band gap width at different frequencies, enhancing the practical value of fractal phononic crystals in engineering applications. This research deepens theoretical understanding and provides valuable guidance for optimizing their use in broadband acoustic control and energy harvesting applications.

Zhang Zhihao, Ye Renchuan, Ji Ming et al.

The Classical Plate Theory (CPT), First-order Shear Deformation Theory (FSDT), and Third-order Shear Deformation Theory (TSDT) have been widely applied in analyzing the Sound Transmission Loss (STL) of composite laminates. However, there are no accurate criteria or formulas to determine the convergence criterion in the process of sound transmission loss analysis. The current method for determining convergence is based on assessing a few typical frequencies to judge convergence across the entire frequency range, resulting in inaccuracies in the high-frequency region and wasting significant computational resources. To address this issue, this paper proposes a new convergence criterion and formula based on CPT, FSDT, and TSDT. These formulas provide a precise framework for determining the optimal number of modes required for convergence, ensuring computational efficiency and accuracy in STL calculations for composite laminates across all frequency ranges.

Sebastian Baltes, Florian Angermeir, Chetan Arora et al.

Large Language Models (LLMs) are now ubiquitous in software engineering (SE) research and practice, yet their non-determinism, opaque training data, and rapidly evolving models threaten the reproducibility and replicability of empirical studies. We address this challenge through a collaborative effort of 22 researchers, presenting a taxonomy of seven study types that organizes the landscape of LLM involvement in SE research, together with eight guidelines for designing and reporting such studies. Each guideline distinguishes requirements (must) from recommended practices (should) and is contextualized by the study types it applies to. Our guidelines recommend that researchers: (1) declare LLM usage and role; (2) report model versions, configurations, and customizations; (3) document the tool architecture beyond the model; (4) disclose prompts, their development, and interaction logs; (5) validate LLM outputs with humans; (6) include an open LLM as a baseline; (7) use suitable baselines, benchmarks, and metrics; and (8) articulate limitations and mitigations. We complement the guidelines with an applicability matrix mapping guidelines to study types and a reporting checklist for authors and reviewers. We maintain the study types and guidelines online as a living resource for the community to use and shape (llm-guidelines$.$org).

Jiaqin He, Max Malyi, Jonathan Shek

Environmental licensing related to underwater acoustic emissions represents a critical bottleneck for the commercial deployment of marine renewable energy. This study presents a control engineering framework to mitigate acoustic risks from tidal current converters without compromising project viability. A MATLAB/Simulink model of a tidal current converter was utilised to evaluate two distinct mitigation tiers: (1) architectural modification, comparing a geared induction generator against a direct-drive permanent magnet synchronous generator, and (2) operational control, analysing the impact of switching frequencies and maximum power point tracking coefficient tuning. Results indicate that lowering switching frequencies is ineffective, increasing power electronic losses by over 2000% with negligible acoustic benefit. Conversely, the direct-drive permanent magnet synchronous generator architecture reduced sound pressure levels, effectively eliminating mechanical tonal noise. For existing geared systems, de-tuning the maximum power point tracking coefficient by a factor of 1.2 reduced the probability of exceeding temporary threshold shift limits for marine mammals, with a quantified energy yield reduction of 3.58%. These findings propose a hierarchical mitigation strategy: selecting direct-drive topologies for acoustically sensitive sites, and utilising maximum power point tracking coefficient based power curtailment as a transient operational mode during critical biological migration periods.

Allysson Allex Araújo, Marcos Kalinowski, Maria Teresa Baldassarre

In recent years, Software Engineering (SE) scholars and practitioners have emphasized the importance of integrating soft skills into SE education. However, teaching and learning soft skills are complex, as they cannot be acquired passively through raw knowledge acquisition. On the other hand, hackathons have attracted increasing attention due to their experiential, collaborative, and intensive nature, which certain tasks could be similar to real-world software development. This paper aims to discuss the idea of hackathons as an educational strategy for shaping SE students' soft skills in practice. Initially, we overview the existing literature on soft skills and hackathons in SE education. Then, we report preliminary empirical evidence from a seven-day hybrid hackathon involving 40 students. We assess how the hackathon experience promoted innovative and creative thinking, collaboration and teamwork, and knowledge application among participants through a structured questionnaire designed to evaluate students' self-awareness. Lastly, our findings and new directions are analyzed through the lens of Self-Determination Theory, which offers a psychological lens to understand human behavior. This paper contributes to academia by advocating the potential of hackathons in SE education and proposing concrete plans for future research within SDT. For industry, our discussion has implications around developing soft skills in future SE professionals, thereby enhancing their employability and readiness in the software market.

Christoph Treude, Marco A. Gerosa

Artificial intelligence (AI), including large language models and generative AI, is emerging as a significant force in software development, offering developers powerful tools that span the entire development lifecycle. Although software engineering research has extensively studied AI tools in software development, the specific types of interactions between developers and these AI-powered tools have only recently begun to receive attention. Understanding and improving these interactions has the potential to enhance productivity, trust, and efficiency in AI-driven workflows. In this paper, we propose a taxonomy of interaction types between developers and AI tools, identifying eleven distinct interaction types, such as auto-complete code suggestions, command-driven actions, and conversational assistance. Building on this taxonomy, we outline a research agenda focused on optimizing AI interactions, improving developer control, and addressing trust and usability challenges in AI-assisted development. By establishing a structured foundation for studying developer-AI interactions, this paper aims to stimulate research on creating more effective, adaptive AI tools for software development.

Jonathan Ullrich, Matthias Koch, Andreas Vogelsang

With the advent of generative LLMs and their advanced code generation capabilities, some people already envision the end of traditional software engineering, as LLMs may be able to produce high-quality code based solely on the requirements a domain expert feeds into the system. The feasibility of this vision can be assessed by understanding how developers currently incorporate requirements when using LLMs for code generation-a topic that remains largely unexplored. We interviewed 18 practitioners from 14 companies to understand how they (re)use information from requirements and other design artifacts to feed LLMs when generating code. Based on our findings, we propose a theory that explains the processes developers employ and the artifacts they rely on. Our theory suggests that requirements, as typically documented, are too abstract for direct input into LLMs. Instead, they must first be manually decomposed into programming tasks, which are then enriched with design decisions and architectural constraints before being used in prompts. Our study highlights that fundamental RE work is still necessary when LLMs are used to generate code. Our theory is important for contextualizing scientific approaches to automating requirements-centric SE tasks.

Maarten Vlaswinkel, Duarte Antunes, Frank Willems

Decarbonization of the transport sector sets increasingly strict demands to maximize thermal efficiency and minimize greenhouse gas emissions of Internal Combustion Engines. This has led to complex engines with a surge in the number of corresponding tunable parameters in actuator set points and control settings. Automated calibration is therefore essential to keep development time and costs at acceptable levels. In this work, an innovative self-learning calibration method is presented based on in-cylinder pressure curve shaping. This method combines Principal Component Decomposition with constrained Bayesian Optimization. To realize maximal thermal engine efficiency, the optimization problem aims at minimizing the difference between the actual in-cylinder pressure curve and an Idealized Thermodynamic Cycle. By continuously updating a Gaussian Process Regression model of the pressure's Principal Components weights using measurements of the actual operating conditions, the mean in-cylinder pressure curve as well as its uncertainty bounds are learned. This information drives the optimization of calibration parameters, which are automatically adapted while dealing with the risks and uncertainties associated with operational safety and combustion stability. This data-driven method does not require prior knowledge of the system. The proposed method is successfully demonstrated in simulation using a Reactivity Controlled Compression Ignition engine model. The difference between the Gross Indicated Efficiency of the optimal solution found and the true optimum is 0.017%. For this complex engine, the optimal solution was found after 64.4s, which is relatively fast compared to conventional calibration methods.

Zihan Ding, Francesco Aletta

Kunqu Opera, hailed as the “ancestor of all Chinese operas”, plays a crucial role in preserving cultural identity and collective memory in the Jiangnan region. This research examines the acoustical traditions of Kunqu. Through expert interviews and thematic analysis, the study explores key acoustic elements, including vocal techniques and musical structures, and their symbolic and emotional impact. Five central themes emerged, including Kunqu’s role in collective memory, its function as a cultural symbol, the evolution of its transmission, the emotional resonance of its acoustic elements, and the modern challenges and opportunities for preservation. The findings highlight the importance of maintaining Kunqu’s cultural identity within acoustical heritage, while also recognizing the need for innovation in its transmission. This research contributes to the broader discussion on intangible cultural heritage and provides insights into how traditional art forms like Kunqu can be preserved amidst modernization.

Oberfeld Daniel, Fischenich Alexander, Ponsot Emmanuel

Non-uniform temporal weights (TWs) are often reported regarding the perceptual evaluation of dynamic auditory and visual information, such as perceptual judgments of the overall intensity of time-varying stimuli. In particular, primacy effects, i.e., a stronger influence of early compared to later stimulus information on the perceptual decision, have been observed across a large number of studies. Yet, it is not clear whether these non-uniform patterns of TWs result from sensory or attentional processes that coincidentally produce similar time-courses, or whether they reflect the common signature of supra-modal and subject-specific decision-making processes. The present study addresses the hypothesis that TWs in loudness (perceived auditory intensity) and brightness (perceived visual intensity) judgments result from a common supramodal evidence-integration process. In Experiment 1, we compared TWs for loudness and brightness judgments in the same participants, with task difficulty matched individually. The observed average temporal weighting profiles differed substantially between the two modalities. In Experiment 2, we assessed the additional contribution of modality-specific sensory and attentional processes to the observed differences between TWs by measuring intensity resolution at different temporal positions in the auditory and visual stimuli. We observed a significantly different dependence of sensitivity on temporal position in the two modalities, but these sensitivity differences only partially accounted for the temporal weighting differences observed in Experiment 1. The collective findings indicate that the TWs observed for loudness and brightness judgments cannot be attributed to a supramodal evidence-integration process alone. Instead, our results suggest that both sensory and decision-making processes shape patterns of TWs.

Müller Leon, Kropp Wolfgang

Electric vehicles (EVs) typically emit little noise at low driving speeds, which increases the risk of accidents for vulnerable road users such as pedestrians. To reduce this risk, regulations demand that newly sold EVs have to be equipped with an acoustic vehicle alerting system (AVAS), which radiates artificial warning sounds. Developing AVAS sounds that provide a sufficient warning capability while limiting traffic noise annoyance requires laboratory listening experiments; such experiments need accurate auralization methods. Even though several auralization tools are already established in the research field, those frameworks require additional data to simulate EVs. This paper presents an electric vehicle auralization toolchain combined with an open-access database, including AVAS measurements, synthesis algorithms, and numerically calculated sound source directivities for three different electric passenger cars. The auralization method was validated numerically and in a listening experiment, comparing simulated EV passages to binaural in-situ recordings. The results of this perceptual validation indicate that stimuli generated with the presented method are perceived as slightly less plausible than in-situ recordings and that they result in a similar distribution of annoyance ratings but a higher perceived vehicle velocity compared to the reference recordings.

Ikoga Shiryu, Onomata Tatsuki, Tabata Ryoya et al.

Recent numerical studies showed that the foot of flue organ pipes closed at one end acts as a Helmholtz resonator and influences the acoustic oscillation in the pipe. Namely, the relative phase of oscillations between the pipe and foot changes depending on the resonance frequency of the foot. This fact can be explained by the theory of forced harmonic oscillators, in which the pipe works as a force driving the foot. However, in the damping-controlled regime, in which the resonance frequency of the foot, fH, is nearly equal to the frequency of acoustic oscillation, fa, the amplitude of the acoustic oscillation is smaller than those in the mass-controlled regime fH < fa and the stiffness-controlled regime fH > fa, even though the pressure oscillation in the foot lags behind that in the pipe by π/2. In this paper, to investigate this problem and to explore the role of the foot in detail, using a three-dimensional model of a closed flue organ pipe, we numerically investigate the relative phases among the pressure oscillation in the pipe, that in the foot and the jet velocity. We conclude that total balance among them is crucial for sustaining acoustic and fluid oscillations in the sound generation process. The oscillating jet drives the pipe with appropriate timing to sustain the acoustic oscillation for the stiffness-controlled and mass-controlled regimes. In contrast, the jet inefficiently drives the pipe with inappropriate timing for the damping-controlled regime.

Haydar Aygun

A computational and theoretical investigation of acoustical and vibrational properties of rigid thin fiberglass material was carried out for different boundary conditions. Fiberglass materials could be applied in industries varying from the aircraft and automotive sectors to the built environment and construction sectors. Plate vibration and acoustic radiation were applied to predict the deflection of the thin fiberglass material and sound radiation efficiency at different locations on its surface, while a study-controlled equation of motion known as the Kirchhoff thin plate theory was applied for a COMSOL simulation of the thin material to determine the deflection of the plate and to obtain stress distribution, velocity contour, displacement, and acoustic pressure at the first resonance of the material. The results of this paper show that thin fiberglass material could be applied to sandwich building elements to form panels for reducing airborne noise and to lessen the sound transmission of structural borne noise, to cover noise barriers to make them more sustainable and weather resistant, to dampen the vibration of machines, and to reduce the structural vibration of buildings.

Emeralda Sesari, Federica Sarro, Ayushi Rastogi

Software practitioners discuss problems at work with peers, in-person and online. These discussions can be technical (e.g., how to fix a bug?) and social (e.g., how to assign work fairly?). While there is a growing body of knowledge exploring fairness problems and solutions in the human and social factors of software engineering, most focus has been on specific problems. This study provides fairness discussions by software practitioners on Stack Exchange sites. We present an exploratory study presenting the fairness experience of software practitioners and fairness expectations in software teams. We also want to identify the fairness aspects software practitioners talk about the most. For example, do they care more about fairness in income or how they are treated in the workplace? Our investigation of fairness discussions on eight Stack Exchange sites resulted in a list of 136 posts (28 questions and 108 answers) manually curated from 4,178 candidate posts. The study reveals that the majority of fairness discussions (24 posts) revolve around the topic of income suggesting that many software practitioners are highly interested in matters related to their pay and how it is fairly distributed. Further, we noted that while not discussed as often, discussions on fairness in recruitment tend to receive the highest number of views and scores. Interestingly, the study shows that unfairness experiences extend beyond the protected attributes. In this study, only 25 out of 136 posts mention protected attributes, with gender mainly being discussed.

Yvonne Dittrich, Johan Bolmsten, Catherine Seidelin

Action research provides the opportunity to explore the usefulness and usability of software engineering methods in industrial settings, and makes it possible to develop methods, tools and techniques with software engineering practitioners. However, as the research moves beyond the observational approach, it requires a different kind of interaction with the software development organisation. This makes action research a challenging endeavour, and it makes it difficult to teach action research through a course that goes beyond explaining the principles. This chapter is intended to support learning and teaching action research, by providing a rich set of examples, and identifying tools that we found helpful in our action research projects. The core of this chapter focusses on our interaction with the participating developers and domain experts, and the organisational setting. This chapter is structured around a set of challenges that reoccurred in the action research projects in which the authors participated. Each section is accompanied by a toolkit that presents related techniques and tools. The exercises are designed to explore the topics, and practise using the tools and techniques presented. We hope the material in this chapter encourages researchers who are new to action research to further explore this promising opportunity.