Search Results (979)

Insulated concrete sandwich panels (ICSPs) are widely utilized in modern building structures due to their excellent combination of energy efficiency and structural load-bearing capacity. However, compared to their mechanical and thermal properties, the sound insulation characteristics of ICSPs remain insufficiently studied, presenting a scientific deficit. In practical engineering, insufficient consideration of these acoustic properties—particularly the “acoustic bridging” induced by connectors—often leads to unpredictable noise transmission, making it difficult for building envelopes to meet stringent modern acoustic codes. To further investigate their acoustic characteristics, this paper extends existing theories on infinite periodic ICSPs to study the airborne sound insulation performance of finite-sized ICSPs. First, analytical models for ICSPs under simply supported on all edges (SS) and clamped on all edges (CC) boundary conditions are derived, wherein the connectors are equivalently modeled as elastic media and discrete elastic springs, respectively. Subsequently, the accuracy and applicability of the analytical models are verified through finite element (FE) models and an airborne sound insulation experiment. Finally, based on the analytical models, a parametric study is conducted to explore the effects of the stiffness of connectors, boundary conditions, and the thickness of the core layer on the sound insulation performance of the ICSPs. The results indicate that connector stiffness has a non-monotonic influence on the sound insulation performance of ICSPs. As the connector stiffness increases, the R_w first decreases and then increases, and the sound insulation performance gradually stabilizes when the connector stiffness becomes sufficiently high. Boundary conditions have a significant effect on the acoustic response. For the reference ICSPs, changing the boundary condition from SS to CC increases the R_w from 49 dB to 62 dB, corresponding to an increment of 13 dB and an approximately 95.0% reduction in the equivalent sound transmission coefficient. When the total panel thickness is kept constant, reducing the core layer thickness from 80 mm to 40 mm increases the R_w from 49 dB to 55 dB under SS boundary conditions and from 62 dB to 66 dB under CC boundary conditions, corresponding to increments of 6 dB and 4 dB, respectively. These improvements are equivalent to reductions of approximately 74.9% and 60.2% in the sound transmission coefficient, though this must be weighed against the inevitable reduction in thermal insulation capacity. Although the sound insulation performance of ICSPs is inferior to that of solid concrete panels (SCPs) of equivalent thickness, with reasonable parameter optimization, their sound insulation indices can significantly exceed the latest requirements of current building codes. By fully accounting for boundary effects in practical engineering, this study provides an analytical basis for the acoustic performance prediction and engineering-oriented optimization of finite-sized ICSPs. Full article

Considering the issue of noise generated by equipment that requires high air permeability for operation, a louvered noise barrier was designed. In accordance with sustainability principles, hemp fiber was used in the louvers. The aim of this experimental research was to investigate the effectiveness of the louvered noise barrier in a semi-anechoic chamber and to evaluate the influence of the number of louvers, the angle of inclination of the louvers, and the hemp fiber density on the performance of the barrier. An investigation of the barrier in a semi-anechoic chamber was carried out, using the rotating microphone method. The louvers in the barrier were tilted at angles of 0, 15, 30, or 45 degrees, and the density of fiber used in the different structures was 50, 100, 150, or 200 kg/m³. The highest insertion loss (IL) of the barrier reached 18.13 dB, and the sound reduction index (R′) reached up to 23.0 dB. The highest determined weighted sound reduction index (R′w) was 14.1 dB, and the equivalent sound level loss (LAeq) reached 9.9 dB (A). Full article

Decarbonization of existing buildings is obstructed by the performance gap between intended and operational energy consumption. Smart energy management and monitoring of existing buildings through digital twins pose significant attributes towards decarbonization efforts. However, there is limited research that transforms digital twins’ monitored performance into actionable retrofitting strategies. Hence, this research develops a framework that bridges the digital twin concept with standards-based IEQ analytics, guiding retrofit decision-making in existing buildings. The framework offers a low-code workflow that uses Autodesk Tandem to develop a digital twin integrating indoor environmental quality (IEQ) data, including thermal comfort and air quality. IEQ is monitored since inefficient management of its parameters often results in excessive HVAC demand, contributing to the performance gap. The framework structures IEQ parameter evaluations against benchmarks guided by ASHRAE to identify deviations indicative of operational inefficiencies in energy consumption. The digital twin model positions live IEQ tracking and analysis as diagnostic measures, leading to targeted fabric-oriented retrofit prioritization. The framework was tested on a case study in a hot arid climate, where its results indicate that the integration of digital twin-based IEQ analysis with building characteristics effectively identified the need for targeted envelope improvements, including high-performance glazing, external shading elements, and sound isolation, as key factors for eliminating overheating and high noise levels. Validating the proposed retrofits’ effectiveness, energy simulations examines the whole building to find an 11.52% annual reduction in energy use intensity from 145.61 kWh/m²·year to 128.84 kWh/m²·year through shading elements and low-E films for glazing. Full article

In this work, an ultrasonic relaxation spectroscopic study of aqueous ammonium Fe(II) sulfate, aqueous ammonium Fe(III) sulfate and the corresponding ternary system has been undertaken. A variety of acoustic parameters including relaxation frequency, relaxation amplitude and speed of sound were determined as a function of solution concentration. In addition, the adiabatic compressibility and the molar volume change during the ionic association in ammonium Fe(II) sulfate and ammonium Fe(III) sulfate aqueous solutions were also estimated from the acoustic data. This approach facilitated a comprehensive characterization of the three systems across different concentrations. In the two binary systems, the presence of an ion association mechanism was identified involving the divalent and trivalent iron ions, with the sulfate anions, respectively. Furthermore, in the ternary system, an internal sphere oxidation–reduction mechanism occurred between the divalent and trivalent iron ions. All ions within each solution play an active role in shaping the structure of water molecules, owing to the prevailing kosmotropic characteristics specific to each solution. The results are examined within the context of the current phenomenological understanding in the field. Full article

Short-term captivity is widely used in experimental studies but may unintentionally alter host-associated microbiomes, potentially confounding biological interpretation of experimental outcomes. Here, we evaluated the effects of 35 days of captivity on the gut microbiome of Fundulus heteroclitus collected from Long Island Sound (Milford, CT, USA) using 16S rRNA gene sequencing. Comparisons between Field Control (FC) and short-term Captive Treatment (CT) groups revealed a marked reduction in microbial diversity under captive conditions. Observed richness decreased approximately five-fold (Field Control: 1026 features; Captive Treatment: 221 features), and Shannon diversity declined from 8.89 to 5.93. Beta diversity analyses based on UniFrac distances demonstrated clear separation between groups, indicating substantial shifts in community composition. Taxonomic profiling revealed reduced community complexity in captive fish, with increased dominance of Proteobacteria and loss of diverse environmental taxa. Predicted enrichment of pathways associated with stress response, altered respiration, and metabolic flexibility in captivity reflects inferred functional potential rather than direct functional activity. Given the use of pooled samples with limited biological replication, these findings should be interpreted as strong community-level patterns rather than population-level inference. Collectively, these results indicate that short-term captivity alters the F. heteroclitus gut microbiome. Full article

Background: The paediatric dentistry domain requires effective management of pain in children during invasive procedures such as the inferior alveolar nerve block (IANB). This study aimed to evaluate the effectiveness of Buzzy BEE^TM in reducing pain perception during IANB in children. Methods: This crossover study recruited 38 children aged 6–10 years scheduled for bilateral dental procedures requiring IANB. The washout period was 7 days, and two visits were scheduled for procedures on either side. Two randomly allocated groups received the study intervention, with each group receiving it alternately at each visit. Outcomes measured were pulse rate; subjective pain assessment using the Wong–Baker FACES Rating Scale (WBS); objective pain assessment using the Sound, Eyes and Motor (SEM) scale; and parental rating of observed pain on a scale of 1–10. Results: A statistically significant reduction in pulse rate after IANB was observed in the Buzzy BEE group at the first (p = 0.02) and second (p = 0.002) visits. At the second visit, the WBS scores (p < 0.001) and ‘eye’ (p = 0.004) and ‘motor’ (p = 0.002) scores on the SEM scale were significantly reduced in the Buzzy BEE group. The crossover analysis identified a significant treatment effect on pulse rate (p < 0.001) and significant carryover effects on WBS and SEM scores (p < 0.001). Conclusions: The use of Buzzy BEE reduced pulse rates during IANB, suggesting a positive impact on children’s anxiety. The carryover effects in the current study limit the consistency of improvements in subjective and objective pain perceptions. Further studies with a larger sample size and an extended washout period are recommended to evaluate the effectiveness of Buzzy BEE in reducing pain perception during IANB. Full article

The particle emissions from diesel engines are a major environmental problem due to their harmful effects on air quality and human health. This article investigates the underlying acoustic parameters that determine the efficiency of reducing the fine particles through agglomeration. The impact of a change in frequency and voltage on the acoustic waves through the excitation source is researched and analyzed. Three blends of rapeseed methyl ester and isopropanol (RME95I5, RME90I10, and RME80I20) are used for experiments to study the combined benefit of oxygen-rich blends. The exhaust particles are measured before and after the exposure to acoustic waves operated at a varying voltage and frequency ranges. The fine particle reduction with a simultaneous increase in 5–10 µm particles is found to be better at the lower frequency due to the severe acoustic attenuation at the higher frequency. With the increase in voltage to 200 V, the reduction in fine particles and the simultaneous increase in coarse particles are comparatively less. The change in voltage induces an increase in sound intensity, which slows down the growth of agglomerates. The study presents the critical information necessary to use acoustic waves to reduce particle pollution using conventional filters, including the mechanisms by which sound intensity affects particle size distribution and the effectiveness of this method in various environmental conditions. Full article

Low-frequency sound insulation remains a major challenge for conventional passive materials, as improved attenuation is usually achieved at the expense of increased thickness and mass. In this work, a smooth fixed third-order ring-curve fractal-maze acoustic metamaterial is proposed for compact low-frequency sound insulation, and a physics-guided long short-term memory–physics prediction surrogate network (LSTM–PPS-Net) tandem framework is developed for its full-spectrum inverse design. Different from conventional Hilbert-type, right-angled, or sharply folded labyrinthine structures, the proposed topology uses recursively arranged curved channels to extend the effective acoustic propagation path and enhance phase accumulation within a limited space. Based on this mechanism, four physically meaningful parameters, namely slit width d, characteristic radius R₃, wall thickness t_w, and inter-column spacing l_E, are selected to construct a low-dimensional design space. A COMSOL–MATLAB automated finite-element method (FEM) workflow is established to generate 1000 valid transmission-loss (TL) spectra over 100–1700 Hz with a 5 Hz interval. For forward prediction, PPS-Net is developed by integrating geometry encoding, frequency-conditioned spectral decoding, and peak-weighted learning. The proposed PPS-Net achieves the best prediction accuracy among the tested models, with a mean absolute error (MAE) of 0.75 dB, a root mean square error (RMSE) of 1.88 dB, and a coefficient of determination (R²) of 0.96, outperforming multi-layer perceptron (MLP), convolutional neural network (CNN) and Transformer models under the same dataset and training protocol. For inverse design, the LSTM encoder extracts frequency-ordered spectral features from the target TL curve, while the frozen PPS-Net decoder provides differentiable acoustic-response feedback, thereby addressing the non-unique mapping from acoustic response to structural parameters. Furthermore, a compactness-oriented optimization strategy is introduced to balance spectral consistency, peak alignment, bandwidth preservation, and occupied-area reduction. In two representative cases, the optimized designs reduce the occupied area by approximately 21% in both representative cases, while maintaining the target attenuation characteristics after FEM verification. These results demonstrate that the proposed framework provides an efficient and physically interpretable route for the full-spectrum inverse design and compact optimization of low-frequency acoustic metamaterials. Full article

The transition toward circular economy practices and CO₂ reduction goals is driving the development of new sound absorption technologies. Traditional absorbers made from mineral wool or foams provide broadband absorption; however, their production is associated with intensive energy consumption and non-renewable resources. This is why the focus has been shifting from the mere substitution of materials to integrated solutions that combine sustainability with structure. This paper reviews recent innovations in sustainable absorbers based on bio-based and recycled materials. The acoustic performance of porous materials depends on such factors such as pore structure, airflow resistivity and geometric parameters such as thickness, multi-layer structure and resonances. At the same time, additive manufacturing (AM) allows creating geometry-controlled absorbers providing advanced acoustic properties. Despite many sustainable absorbers demonstrating sufficient sound absorption properties at medium and high frequencies, their use at low frequencies remains challenging. Additionally, concerns regarding durability, flame retardance, and environmental consistency continue to limit their broader application. Yet, hybrid, multi-material strategies, particularly those combining geopolymer matrices with bio-based or recycled fillers, are identified as a promising route to address these limitations. This review outlines current trends and highlights key challenges and future directions in the design of sustainable sound-absorbing systems. Full article

Experiencing the forest landscape in its natural state is one of the factors that positively affect people, especially younger generations exposed to stress. The study assessed the impact of listening to nature sounds and observing forest landscapes on the mood and well-being of young adults exposed to a real forest environment. The experiment consisted of two sessions, allowing us to compare the regenerative effects of observing the forest with full engagement of the senses of sight and hearing, and by listening exclusively to the sounds of nature (birdsong, rustling leaves). The relaxation benefits were compared using psychological tests, including the Positive and Negative Affect Schedule (PANAS), Profile of Mood States (POMS), Restorative Outcome Scale (ROS), and Subjective Vitality Scale (SVS), administered before and after each exposure. The study involved 31 volunteers from Warsaw, the Polish capital (17 women and 14 men, with an average age of 25). A significant improvement in mood (as measured by the POMS) was observed, particularly through a reduction in Anger and Confusion. Both sessions (with and without a blindfold) significantly reduced negative affect (PANAS Negative) and increased restorative outcomes (ROS). However, no significant differences were found between full immersion (sight and hearing) and auditory-only exposure, suggesting that the acoustic layer of the forest environment plays a dominant role in the short-term psychological regeneration of young adults. In summary, these results suggest that both forms of exposure to nature have a relaxing effect on humans. However, full immersion, which involves being in the forest and viewing it, combined with listening to the sounds of nature, provides by far the most benefits for improving the well-being and mood of forest visitors. Full article

Background: Tinnitus is a prevalent auditory disorder associated with maladaptive cortical plasticity and aberrant neural synchronization across auditory and non-auditory brain networks. Acoustic desynchronization-based sound therapies, such as coordinated reset neuromodulation, aim to counteract pathological oscillatory patterns but commonly require prolonged daily listening sessions and specialized delivery formats, which may limit their accessibility and practicality in routine clinical settings. To address this limitation, a modified desynchronization protocol embedding therapeutic tones within music was developed to improve tolerability and engagement. This study aimed to evaluate the clinical effects of modified Music-Integrated Desynchronization Sound Therapy (mMIDST) on tinnitus severity in patients with chronic tinnitus. Methods: In this prospective, randomized, controlled, single-blind pilot trial conducted at the Otolaryngology Department of Hospital Clínico Universidad de Chile (Santiago, Chile) between July 2024 and July 2025, adults aged 18–75 years with chronic non-pulsatile tinnitus were assigned to receive either mMIDST or an active control intervention consisting of low-frequency stimulation (LFS) embedded within identical music tracks. Participants listened to personalized sound files for one hour daily, five days per week. Tinnitus severity was assessed using the Tinnitus Handicap Inventory (THI), with audiometric evaluations performed at baseline and after one, two, and three months. Between-group differences were analyzed using the Mann–Whitney U test. Results: Twenty-five participants completed the study (15 mMIDST, 10 LFS). Baseline audiometric thresholds and THI scores were comparable between groups. The mMIDST group showed significantly greater reductions in THI scores than the LFS group at two and three months of treatment (p < 0.05). Conclusions: mMIDST was associated with time-dependent improvements in tinnitus-related distress compared with an active control condition. Embedding desynchronization-based tonal stimulation within music may represent a promising and well-tolerated non-invasive approach for chronic tinnitus management. Full article

Aiming at the technical bottleneck that traditional porous structures can hardly achieve mechanical load-bearing and acoustic regulation simultaneously, this study designs and fabricates three implicit surface porous structures (Gyroid, Diamond, Lidinoid) based on the bionic principle of trabecular bone. Experimental characterization and numerical analysis of their mechano-acoustic coupling performance are systematically carried out. Selective Laser Melting (SLM) technology is employed to realize the integrated forming of 316L bionic structures. Quasi-static compression experiments and finite element simulations are conducted to reveal the progressive deformation mechanism and energy absorption characteristics of different topological configurations. The results indicate that the Diamond structure exhibits the optimal comprehensive performance in terms of load-bearing capacity, specific energy absorption and isotropy. On this basis, the sound absorption and sound insulation performances of the structures are evaluated via an acoustic impedance tube test. The results show that the Diamond structure possesses a remarkably higher sound absorption coefficient and sound insulation value in the high-frequency range than other configurations, demonstrating excellent acoustic energy dissipation and sound wave isolation capability. The research indicates that the synergistic optimization of mechanical and acoustic performances can be achieved by regulating the Triply Periodic Minimal Surface (TPMS) topological configuration. Benefiting from its efficient stress transfer paths and intricate sound wave propagation channels, the Diamond structure realizes the coupling of high load-bearing capacity, superior energy absorption and favorable acoustic performance. This work provides a theoretical basis and technical support for the design of bionic porous structures in multifunctional scenarios such as bone implants and protective noise reduction. Full article

This study proposes a rigorous methodology for the optimal placement of voltage regulators in the Guayacanes feeder of the Buena Fe substation, Ecuador, by integrating electrical feeder modeling, exhaustive search, and multi-criteria decision-making. The feeder was modeled in detail by incorporating its radial topology, nodal electrical parameters, and representative operating conditions under minimum- and maximum-load scenarios. Based on this model, a set of technical evaluation criteria was established to quantify the impact of regulator installation, including active power losses, reactive power losses, global voltage deviation, average voltage variation, and voltage imbalance. An exhaustive search strategy was then implemented to evaluate all feasible regulator-location alternatives over the candidate nodes, thereby ensuring a complete exploration of the solution space. The resulting alternatives were ranked using the Weighted Sum Method (WSM) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS), allowing the comparison of candidate locations from a multi-criteria perspective. The results indicate that node MTS 108932 provides the most technically favorable overall solution, achieving the greatest improvement in voltage profile quality and the most significant reduction in electrical losses. In addition, a sensitivity analysis was conducted by varying the weighting structure of the decision criteria, confirming the robustness of the selected alternative under different decision-maker preference scenarios. The proposed framework provides a technically sound decision-support methodology for voltage regulation planning in real radial distribution systems. Full article

This study investigates the coupling between flow dynamics, acoustic response, and convective heat transfer in a rectangular impinging jet striking on a heated slotted plate at two closely spaced Reynolds numbers (Re = 3550 and Re = 3750). Velocity fields were obtained using Particle Image Velocimetry (PIV), and coherent structures were analyzed using Proper Orthogonal Decomposition (POD) while acoustic measurements were used to characterize the tonal behavior. Infrared thermography was employed to determine local and mean Stanton numbers. The mean Stanton number increased by 6.6% when the Reynolds number increased from Re = 3550 to Re = 3750, while the sound pressure level decreased from 78 dB to 71 dB. At Re = 3550, the acoustic spectrum exhibited multi-tone behavior associated with distributed modal energy. In contrast, at Re = 3750, a single dominant frequency governed the flow dynamics. The energy of the first POD mode nearly doubled when passing from Re = 3550 to Re = 3750. The cross-correlation coefficients between the first POD mode and the acoustic field increase from 0.76 to 0.93 when changing from Re = 3550 to Re = 3750. These findings show that the dominant vortex mode which contains nearly 20% of the fluctuating energy (for Re = 3750), significant influences the energy transfer from the dynamic field to the acoustic field resulting in a strong noise reduction. Simultaneously, convective heat transfer increases, highlighting the key role of coherent flow organization on both acoustic and thermal behavior of the system. Full article

Meat from culled cows is characterized by increased toughness and limited processing suitability, yet the combined effects of microbial cultures and mechanical processing have not been sufficiently studied. The aim of this study was to evaluate the effect of Lactobacillus sakei (SafePro B-2, 10¹¹ CFU/g) in combination with vacuum massage on the physicochemical, structural, and functional–technological properties of culled cow meat, as well as to optimize the process using response surface methodology. It was found that the combined treatment led to a 25–35% reduction in shear force and a 12–18% increase in water-holding capacity compared to control samples. The pH value decreased from 6.2 to 5.6–5.8, indicating active lactic acid fermentation. Modeling using the response surface method demonstrated high predictive power of the models (R² = 0.91–0.96) and allowed for the determination of optimal process parameters (10⁷ CFU/g; 40 min of mixing), ensuring maximum softening and product stability. Analysis of the texture profile revealed a statistically significant (p < 0.05) decrease in hardness, stickiness, and chewiness, accompanied by an increase in cohesiveness, indicating a reorganization of the protein matrix at the microstructural level. Additionally, microstructural modifications and reorganization of the protein matrix were observed, accompanied by changes in amino acid composition, indicating a change in the state of proteins and their spatial distribution within the meat matrix. Overall, the combined use of Lactobacillus sakei and vacuum massaging effectively improves the functional, technological, and structural characteristics of low-grade beef raw materials. The proposed approach can be considered a scientifically sound strategy for optimizing processing parameters and increasing the efficiency of utilizing meat from culled cows. Full article