Evaluation of a stable non-aqueous coupling medium for transcranial ultrasonic stimulation and sonogenetics.

Extreme weather events, such as tropical storms, can pose profound disruption to nearshore marine environments. Although coastal ecosystems are particularly vulnerable to storm impacts, research describing the response of marine taxa to extreme weather remains limited, especially for highly mobile marine predators. In this study, we use acoustic telemetry to investigate the behavioral responses of juvenile white sharks (Carcharodon carcharias) at a Southern California nursery aggregation site to Tropical Storm Hilary in 2023. To aid in these efforts, we developed a novel occupancy modeling approach to statistically account and correct for temporal variations in acoustic receiver performance during disruptive storm conditions. Using detection data from synchronization transmitters, we first estimated the effects of key environmental factors on transmitter detection efficiency, with ambient noise, receiver tilt, and the density of animal transmitters present inside the receiver array emerging as particularly influential predictors. We then leveraged these estimated effects to inform a Bayesian state space model designed to investigate nursery occupancy dynamics, including environmental drivers of nursery emigration. Our results provide evidence of partial nursery evacuation, with over half of tagged sharks temporarily leaving monitored nearshore habitats in response to peak storm conditions. However, most emigrations were short-lived, with all but one shark returning to the aggregation site within three weeks of the storm. Evacuations from nursery habitats were best predicted by falling sea surface temperatures, although increased wave height, declining barometric pressure, and drops in salinity may have served as important secondary flight cues. Our efforts provide a rare opportunity to document the storm response behaviors of a recovering top predator, while also presenting tangible analytical solutions to commonly encountered technical challenges in the field of acoustic telemetry.

Porous AlPO4 ceramic with high strength and good acoustic performance prepared by direct foaming and gel-casting

Sustainable gellan gum/microcrystalline cellulose foams: Preparation, characterization, and acoustic performance.

This study presents a single-case multi-sensor experimental study of thermal loading and emission variation in a high-mileage gasoline engine operating at idle under deliberately impaired cooling until mechanical failure. A production vehicle equipped with a naturally aspirated gasoline engine with a displacement of 1600 cc was operated under relatively steady-state conditions at idle, while gaseous emissions (CO, CO2, HC, NOx, and O2), air–fuel ratio λ, particle number (PN), oil temperature, infrared thermal indicators, and acoustic performance variation were continuously monitored. The results are interpreted primarily in terms of their dependence on the engine oil temperature. They show that despite stable conditions of the air–fuel ratio and an almost constant amount of residual oxygen in the exhaust gases, progressive thermal loading leads to pronounced changes in the behavior of the emissions emitted by the engine during its operation. Hydrocarbon emissions show increased variability and escalation at elevated engine oil temperatures, while nitrogen oxides show a strong temperature-dependent increase, consistent with thermally driven formation mechanisms. The most significant response is observed in the particle number (PN) emissions, which go from low and stable levels to a rapid, multi-step increase in a narrow temperature range preceding mechanical failure. Under the tested cooling impairment scenario, emission behavior was dominated by cumulative thermal stress rather than mixture composition effects. In the investigated case, particle number emissions emerged as a sensitive indicator of system-level thermal instability. The findings provide experimentally documented insight into the system-level progression toward thermal runaway under impaired cooling conditions and its measurable impact on emission behavior in the tested engine.

Architectural textiles also known as Architextiles is a multi-disciplinary intersection of textile science and architectural design where lightweight, flexible and high-performance built environments are achieved. Architectural textiles are based on the combination of architecture and textiles, and can be used as structural and non-structural items, acting as facades, roofing systems, shading systems, interior, and energy-generating building skins. The paper focuses on the review of materials, structures, properties, and emerging technologies that relate to architextiles, which have become increasingly significant in the sustainable and innovative architectural practices. The research considers a broad spectrum of fibres, which is natural fibres, synthetic fibres, high-performance fibres, metallic fibres, woven fabrics, knitted fabrics, braided fabrics, nonwoven fabrics, and spacer fabrics, among others that have been used in architectural work. This is done in relation to the coating that is used like PVC, PTFE, silicone and PVDF or fibre reinforced composite like structural efficiency, durability, weatherability, and fire resistance. The architextiles performance requirements (tensile and tear strength, flexibility, UV and fire, light transmission, thermal and acoustic performance and energy efficiency) are examined with references to the recent experimental studies. Moreover, the paper discusses various uses of architextiles such as tensile and pneumatic buildings, facades, shading systems, roofing, green textile roofs, interior textile systems, acoustic and thermal insulation, landscape architecture and cheap and living solutions. New possibilities of nanotechnology, phase change materials, biomimicry, and energy-harvesting textiles are critically considered with an emphasis on the possibilities to improve the performance and sustainability of buildings. Durability issues, cost, lifespan, as well as complexity of installation are discussed as well. Comprehensively, the paper highlights the role of architextiles as a revolutionary material system capable of supporting adaptive, energy-saving, and expressive buildings, which makes them one of the primary constituents of the sustainable building industry and intelligent building construction in the future.

The Royal Festival Hall (RFH) in London, opened in 1951, is renowned architecturally but has long-standing acoustic challenges affecting clarity, warmth, and reverberation. This study investigates the hall’s acoustic performance and evaluates interventions to improve its auditory qualities other than pursuing the idea of changing theatre chairs since the focus has been on this topic. Acoustic measurements of existing theatre chairs were conducted using a Microflown sensor, and the data were incorporated into a geometrical acoustics model to simulate the effects of a sustainable plant-based leather (Piñatex) covering. Simulations considered both unoccupied and occupied conditions, alongside modifications to architectural elements, including curtains on balconies, ceiling reflectors, and increased floor and wall mass. Results show that Piñatex improves reverberation time at mid and high frequencies under unoccupied conditions but has negligible effect when the hall is fully occupied. Additional architectural interventions enhance reverberation and other parameters, including clarity (C50, C80) and strength (G), although low-frequency response remains limited. This study highlights that the hall’s shallow and wide form constrains acoustics, suggesting that structural adjustments or reinforcement sound systems are necessary for an optimal room’s response.

<div>The increasing demand for quiet and efficient electric vehicles has highlighted the importance of understanding vibration and noise characteristics of motor stators. Previous studies have extensively modeled electromagnetic excitation and laminated structures, but there has been little experimental evidence clarifying how different interlaminate fastening methods affect vibration modes under comparable conditions. This knowledge gap limits the ability to optimize fastening strategies for noise and vibration control in practical motor design. In this study, laminated stator cores were fabricated with different fastening conditions—bolting, clinching, and welding—and subjected to vibration testing and experimental modal analysis. Natural frequencies, damping ratios, and mode shapes were identified for torsional, circumferential, and breathing modes. The results revealed that the in-plane torsional natural frequencies increase with bolt axial force, while clinching provides additional resistance to interlaminate movement but shows only a minor dependence on the number of clinching points. In contrast, the circumferential modes and the breathing-type (0,0) mode remain largely unaffected by these fastening variations. Welding points did not exhibit a consistent trend across the tested conditions, indicating that their influence on the modal properties is less systematic compared with bolting and clinching. The findings contribute not only to fundamental understanding of laminated stack vibration behavior but also to practical guidelines for designing fastening strategies that enhance vibration robustness and acoustic performance in automotive electric motors.</div>

In the field of cultural architecture design, the deep impact mechanisms of wooden material design perception on users’ psychological experiences have not yet been fully elucidated. The interior environmental design of concert halls, as venues for immersive artistic experiences, especially the use of natural materials such as wood, is considered a key factor shaping audience perception and experience. However, existing research has largely focused on the acoustic performance of or visual preferences for wooden materials, while there remains a lack of mechanistic explanations for how wooden design perception systematically enhances users’ overall satisfaction through a series of internal psychological processes. Based on the “stimulus–organism–response” theoretical framework, this study proposes a chain mediation model aimed at exploring how perception of wooden design in concert halls enhances user satisfaction by promoting users’ flow experience and subsequently strengthening their place attachment. Through a cross-sectional survey of 1017 audiences with actual experience in wooden concert halls and analysis of the data using covariance-based structural equation modeling, the findings reveal that: (1) perception of wooden design has a significant direct positive effect on user satisfaction; (2) both flow experience and place attachment independently mediate the influence of wooden design perception on user satisfaction; (3) there exists a significant chain mediation path: “perception of wooden design → flow experience → place attachment → user satisfaction”. This study validates, from an architectural psychology perspective, the role of flow and place attachment as consecutive psychological mechanisms. The research provides empirical evidence for architects to use wood as a psychological intervention tool in cultural spaces, transforming material selection from an aesthetic consideration into a systematic design strategy with measurable psychological outcomes.

In the present investigation, the temperature-dependent elastic, mechanical, thermal and acoustic features of terbium monopnictides (TbX; X [Formula: see text] As, Sb, Bi) in rock-salt (B1) structure have been theoretically investigated. The second-order elastic constants were calculated to assess mechanical stability and anisotropy. Key mechanical parameters — Young’s modulus, shear modulus, bulk modulus, Poisson’s ratio and compressibility — have been evaluated and visualized in 2D and 3D to investigate elastic anisotropy. Ultrasonic velocities (longitudinal, transverse and average), Debye temperature, thermal conductivity and thermal relaxation time were also estimated to understand the phonon transport and acoustic performance of the selected TbX. The results reveal significant thermal sensitivity in elastic and thermomechanical responses, with systematic trends across the pnictogen series. These findings highlight the potential of TbAs, TbSb and TbBi for high-temperature and high-frequency applications, including thermoelectric energy conversion, advanced microelectronics and thermal management systems.

The current global context, characterized by climate change and increased indoor occupancy, has necessitated prolonged daily operating hours for ventilation systems. Coupled with rising living standards, these factors have elevated occupants’ expectations for Indoor Environmental Quality (IEQ), driving a demand for quieter equipment which is a significant challenge for HVAC engineering. This study evaluates the acoustic attenuation performance of various casing constructions to quantify the impact of sheet metal stiffness compared to insulation thickness. Experimental measurements of the Radiated Sound Power Level (LwA) were conducted on a heat recovery unit across octave bands from 63 Hz to 16,000 Hz, ensuring a measurement uncertainty within ±0.5 dB as per ISO 3741 precision requirements. The methodology involved testing multiple enclosed configurations against a reference open-top unit, varying mineral wool insulation thickness from 40 mm to 100 mm (with optional 25 mm linings) and inner sheet metal thickness between 0.8 mm and 2.0 mm. The results indicate that enclosing the unit significantly reduced radiated sound power levels compared to the exposed reference. While the standard configuration with 50 mm insulation yielded 49.8 dBA, modifying the casing structure generated superior attenuation. Notably, a configuration utilizing a 2.0 mm inner sheet resulted in a radiated sound power level of 46.9 dBA, a result found to be statistically significant (p < 0.05) when compared to the baseline. This performance is statistically comparable to the 46.7 dBA recorded for the maximum insulation assembly, confirming the validity of structural stiffening as an equivalent alternative to bulk insulation. Consequently, the increased panel stiffness achieved approximately 94% of the attenuation efficiency provided by the thickest insulation option. The data demonstrates that increasing panel stiffness effectively reduces transmission, offering performance levels comparable to significantly thicker insulation layers. The study concludes that optimizing casing stiffness represents a superior strategy for noise control in high-density residential applications, as it decouples acoustic performance from the unit’s external dimensions, offering a high-attenuation solution that preserves a compact spatial footprint.

Statement of Problem. The increasing demand for sustainable and energy-efficient materials has prompted the evaluation of lightweight fibre-reinforced concrete, which exhibits notable acoustic and mechanical performance. The work aims to study the mechanical and acoustic properties of hemp fibre integrated as a natural reinforcement and perlite granules as a lightweight aggregate. Five mixed proportions are developed with a conventional mix and others with 7 % perlite replacement and hemp fibre addition of (0.5, 1.0, and 1.5 % by volume). Mechanical behaviour, density and water absorption are evaluated to evaluate the effect of material modification. An impedance test is conducted to determine the sound absorption coefficient at frequencies of 250, 500, 1000, and 2000 Hz. Result. Results showed that compressive strength decreased with increasing fibre and perlite content, attributed to increased porosity and disrupted matrix compaction. The density decreased gradually with the material of altered proportions, and the reason was to use lightweight concrete. Sound absorption was increased reaching a peak of 0.35 at 1000Hz with a 1.5 % addition of hemp. Conclusion. The study introduces the efficacy of the mixture of hemp fibres and perlite granules and powder together to improve the acoustic performance and strength to be applicable in non-structural sound-sensitive conditions. The results are used in the creation of environmentally-friendly, acoustic materials that are lightweight and designed to meet the contemporary construction demands.

The multilayer sound absorber (MSA) is typically a composite structure that consists of a micro-perforated panel (MPP) with circular perforations, a layer of porous material, and an air gap. This combination enhances the sound absorption coefficient (SAC) across a broad frequency range. However, the sound absorption mechanisms of the MSA when incorporating polygonal cross-section perforations have not been thoroughly investigated. In this paper, the acoustic impedance of MPP with square or equilateral triangular cross-section perforations is simply given based on a complex density function and the radiation impedance in short tubes with square cross-sections. Theoretical acoustic impedance models are established for three configurations: CMSA (circular perforations), SMSA (square perforations), and EMSA (equilateral triangular perforations), using the transfer matrix method (TMM). To validate these models, SAC measurements were conducted via an impedance tube, showing good agreement with theoretical predictions. Further analysis of the acoustic performance revealed that the SMSA configuration exhibits a higher resonance peak and a broader absorption band. Finally, a simple optimization of the hole diameter and air gap was performed using an oppositional Runge Kutta optimizer with cuckoo search (OCRUN). The results demonstrate that the EMSA achieves quasi-perfect sound absorption within specific frequency bands using a smaller air gap compared to both CMSA and SMSA.

ABSTRACT This study investigates the acoustic performance of multilayer bio‐based composites composed of alternating layers of Luffa Cylindrica (LC) and electrospun cellulose acetate/polyvinylpyrrolidone (CA/PVP) blended microfibers. A principal outcome is that the incorporation of CA/PVP microfibers markedly enhances the sound absorption behavior of the composites. Compared with PVP‐free (CA‐only) counterparts, the LC/CA‐PVP multilayer configuration enables more efficient acoustic wave dissipation and produces a shift of the sound absorption coefficient peak toward lower frequencies, together with a slight increase in average sound absorption. This shift toward lower frequencies is particularly relevant, as traffic and urban noise typically contain a substantial proportion of low‐frequency acoustic energy. Overall, the integration of CA/PVP electrospun microfibers into LC‐based multilayer composites improves functional acoustic performance without compromising the bio‐based nature or lightweight characteristics of the materials. From an application standpoint, these results highlight the potential of the proposed multilayer composites for sustainable noise control, especially in urban and traffic‐related settings where effective low‐frequency noise attenuation is required. Moreover, the ability to tailor absorption characteristics through the composition of microfibrous layers demonstrates the flexibility and practical relevance of the proposed design strategy.

This study presents a detailed investigation of the acoustic performance of roller shutter boxes in the extended position, comprising porous and heavy mass layers. Such configurations are of particular relevance, as roller shutter boxes often represent weak points in the façade sound insulation of residential and office buildings. The Finite Transfer Matrix Method (FTMM) is first employed to model the system, providing a robust description of its acoustic properties, with numerical predictions validated against laboratory measurements. A two-step global sensitivity analysis is then performed to identify the dominant parameters. The Morris method is initially applied to screen mechanical, acoustic, and geometric variables, followed by the computation of Sobol indices to quantify the influence and interactions of the retained parameters. Given the high computational cost of Sobol analysis for complex models, several metamodeling techniques are evaluated, including Polynomial Chaos Expansion, Kriging, and Polynomial Chaos Kriging (PCK). Among these, PCK is shown to provide the most accurate and efficient framework for estimating sensitivity indices. Finally, an optimization procedure based on a genetic algorithm is conducted on the micro-macro model of polyurethane foams, focusing on controllable material parameters. The results emphasize the critical role of the reticulation rate in enhancing the sound transmission loss of extended roller shutter boxes.

Achieving continuous high absorption at low frequencies remains a persistent challenge in acoustics. Conventional sound-absorbing structures struggle to mitigate low-frequency noise within limited spatial constraints. To address this, we propose an acoustic metasurface based on coupled acoustic coils, which is capable of customized absorption bandwidth performance in the low-frequency range. Each acoustic coil incorporates porous material linings on its inner walls, whose thickness can be tuned to precisely modulate damping properties, resulting in perfect absorption. By arranging multiple coils in parallel, the metasurface generates continuous absorption peaks across low frequencies, and the parameters such as the truncation ratio enable precise band customization. A theoretical model grounded in double porosity theory is established to analyze the acoustic performance of the proposed metasurface. The complex frequency plane analysis method is employed to characterize the system damping behavior. Results demonstrate that adjusting the thickness of the porous linings can readily induce critical damping behavior and perfect absorption. Parametric studies of entrance length and truncation ratio confirm the exceptional tunability of the coils. This leads to a coupled absorber achieving near-perfect absorption α>0.9 at frequencies as low as 295–355 and 229–264 Hz with a compact thickness of 45 mm. The proposed structure and its design methodology are expected to advance the development of acoustic metasurfaces.

Amid increasing demand for energy efficiency and reduced CO2 emissions in the building sector, natural fibres such as sheep wool are gaining attention as a sustainable raw material for low-impact insulation materials. This review summarises the current state of research on the thermal and acoustic properties of sheep wool-based composites and their applications in low-carbon construction. The fibre structure, thermal conductivity, hygroscopicity, heat storage capacity, and sound absorption coefficient are discussed, highlighting the competitiveness of sheep wool compared to conventional synthetic and mineral materials. The review also addresses the use of wool fibres in cement composites, insulation panels, sound-absorbing materials, and sorption mats, emphasising their potential in humidity regulation, acoustic comfort, and circular economy strategies. A literature analysis indicates that utilising sheep wool waste can reduce environmental impact, lower the carbon footprint of building materials, and enhance local agricultural value. The review provides an overview of current knowledge on sustainable sheep wool-based insulation materials and focuses on an interdisciplinary and quantitative approach to the thermal, acoustic, and environmental performance of composites based on waste sheep wool, combined with an analysis of their applicability in low-carbon construction and circular economy frameworks. Future research should focus on assessing long-term durability, material ageing under real service conditions, and standardised life cycle assessment (LCA) methodologies to enable reliable comparison with conventional insulation materials.

The demand for high-performance filters in next-generation wireless communication systems underscores the limited electromechanical coupling of aluminum nitride-based film bulk acoustic resonators. Scandium incorporation enhances piezoelectricity but is hindered by crystallinity degradation and polarity inversion. Theoretical modeling reveals the polarity inversion interface between aluminum nitride and scandium-doped aluminum nitride as a key cause of piezoelectric degradation. This work proposes a dual-optimization strategy that improves crystalline alignment and eliminates polarity mismatch. A single-crystalline aluminum nitride seed layer promotes high c-axis oriented scandium-doped aluminum nitride films, yielding resonators with a maximum quality factor of 736. Subsequent seed layer removal eliminates the polarity inversion interface, raising the effective electromechanical coupling coefficient of resonators from 6.0% to 13.2%. Filters fabricated with this strategy achieve a center frequency of 6.4 GHz, a 3 dB bandwidth of 740 MHz, and out-of-band rejection above 40 dB, indicating potential for Sub-7 GHz communication systems.

This study employed an integrated experimental–computational methodology to investigate the critical role of the layer-stacking sequence in the acoustic performance of multi-layer porous materials for vehicle NVH applications. The acoustic properties of four distinct single-layer materials were first characterized via impedance tube measurements. A finite element simulation model based on the Johnson–Champoux–Allard (JCA) theory was subsequently developed in COMSOL Multiphysics 6.2 and rigorously validated. Leveraging this validated model, a systematic analysis was conducted on six different layer sequences under a fixed total thickness of 30 mm. The simulation results showed excellent agreement with experimental data, with a root-mean-square error (RMSE) below 5%. It was demonstrated that the stacking sequence significantly governed the mid-to-high frequency sound absorption behavior, which was strongly correlated with the modulation of the real and imaginary parts of the normalized surface acoustic impedance. This study thus demonstrated that the layer sequence—a previously underexplored design factor—critically determines the absorption performance of multi-layer materials at a fixed total thickness. A full design-space analysis revealed that performance shifts are governed by changes in interfacial acoustic impedance. This physics-driven insight provides a practical framework for tailoring absorbers to specific frequency bands, offering a viable path toward lightweight acoustic solutions for electric vehicle applications.

Aeroacoustic metastructure: Toroidal propeller with enhanced acoustic and aerodynamic performance