Vol. 60 No. 4 (2026)

Open Access

Article

Article ID: 1706

Prediction of heart sound using the xLSTM method for hypertrophic cardiomyopathy

by Shatiswaran Vigian, R Kanesaraj Ramasamy, Junaidi Abdullah

Sound & Vibration, Vol.60, No.4, 2026;

Heart disease has emerged as a major global public health concern, driven by poor dietary habits, unhealthy lifestyle choices, and limited health awareness. Accurate diagnosis of cardiac conditions remains challenging for hospitals and clinical institutions. Hypertrophic cardiomyopathy is an autosomal dominant disorder caused by mutations in sarcomere protein genes that affect the contractile function of cardiac muscle. With the growing adoption of digital health systems, large volumes of patient data are now collected and stored, providing opportunities for computational approaches to support clinical decision making. Machine learning methods have become increasingly important for analysing complex and nonlinear patterns in medical data. This study presents an ensemble-based approach for heart sound classification and introduces an Extended Long Short-Term Memory (xLSTM) model for the detection of cardiac abnormalities. The method was evaluated using acoustic features extracted from phonocardiogram recordings. The proposed model achieved 96.93% accuracy, 93.50% sensitivity, and 99.63% specificity, indicating strong performance in distinguishing normal and abnormal heart sounds. In comparison with previously reported techniques, the ensemble strategy and the xLSTM architecture provided improved accuracy. Model performance was assessed using accuracy, precision, recall, and F1 score, confirming the effectiveness of the proposed approach for automated heart sound analysis.

Open Access

Article

Article ID: 4028

A framework of structural health monitoring integrated with deep learning schemes to estimate the displacement of 3D LiDAR scanning on bridges

by Wael A. Altabey

Sound & Vibration, Vol.60, No.4, 2026;

In recent decades, the rapid development of transportation infrastructure safety, such as highways, bridges, and tunnels has greatly promoted the development of the regional economy. The structures with safety hazards and emergencies need continuous monitoring over time. The integrated artificial intelligence algorithms with sensor responses can provide real-time information for further analysis and decision-making for the transportation system, improving the circulation efficiency of the transportation network, ensuring the stability of road structures, and avoiding irreparable damage. This paper aims to develop an efficient and low-cost method to help detect early-stage transportation infrastructure damage through permanent or periodic monitoring. In this research, we used LiDAR scanning units (terrestrial LiDAR fixed on holders and movable units fixed on UAVs) integrated with a novel deep neural network (DNN) for structural monitoring of bridges based on the 3D mapping of bridge displacement compiled from LiDAR scanning over time. The monitoring model is based on a recurrent neural network with long short-term memory blocks (RNN-LSTM) since the LiDAR scanning datasets have a time-dependent and memory-dependent behavior. The response of the proposed DNN achieved a high accuracy rate, regression rate, and F-score equal to 96.43%, 93.77%, and 91.65%, respectively. A deep analysis of the confusion matrix and a side-by-side look at predicted and actual conditions highlight how well the model can tell apart different traditional methods to estimate the bridge displacement in literature. So, the data from LiDAR and DNN models can be combined to analyze the monitoring of transportation infrastructure.

Open Access

Article

Article ID: 4013

Complaint-guided robust optimization of highway noise barriers with hourly traffic variability

by Yogeesh Nijalingappa, Markala Karthik, Asokan Vasudevan, Mohammed Almakki, Zetty Pakir Mastan, Mayibongwe Tafara Mudzengi

Sound & Vibration, Vol.60, No.4, 2026;

Road-traffic noise is a daily problem in many fast-growing tier-2 cities. On busy corridors, mixed traffic and stop-go movement raise both exposure and public annoyance. This study presents an uncertainty-aware framework for optimizing roadside noise barriers by combining hourly traffic variability with community complaint signals. The NH-48 urban approach corridor in Tumakuru, Karnataka, was examined using a 7-day dataset at hourly resolution. A calibrated baseline model related hourly A-weighted equivalent sound levels to log-scaled traffic flow, mean speed, and heavy-vehicle fraction, with good agreement with measurements (overall MAE 2.3 dB(A), RMSE 3.1 dB(A)). Input uncertainty was represented through nested α-cut interval bands, and the measured hourly levels were increasingly captured as the bands widened (coverage from 0.66 at α = 0.8 to 0.92 at α = 0.2). Barrier design was posed as a multi-objective robust optimization problem that minimized conservative exceedance, complaint-weighted nuisance, and a normalized cost index. The evolutionary search produced a Pareto set with a clear cost-performance trade-off. The preferred solutions lowered robust exceedance and complaint-weighted objective values by up to 35% and 42%, respectively, relative to baseline candidates. Receptor-level exceedance hours fell by about 39–45%, and mean upper-bound levels dropped by as much as 3.9 dB(A) at near-road receptors. Overall, the results show that complaint signals can help identify perceptual hotspots, while the uncertainty-aware model maintains robust exposure reduction under day-to-day traffic variation.

Open Access

Article

Article ID: 4069

Parametric sensitivity analysis of impact-induced vibration in revolving cannon systems using the PCE surrogate model

by Junyu Shan, Ming Hu, Shuai Yue, Zhonghua Du, Zihao Wang

Sound & Vibration, Vol.60, No.4, 2026;

To solve impact vibration problems brought by impacts between sliding plates and rotating chamber structures when revolver shooting processes go on, a parameterized dynamic model which includes gas-driven mechanisms and curved chamber contact relations has been constructed. The accuracy of the model has been verified by means of chamber pressure measurement experiments and high-speed photography experiments. For overcoming the computation restriction problems of high-precision simulated experiments, a sparse polynomial chaos expansion method has been utilized by us for building a high-accuracy substitute model. In combination with the Sobol global sensitivity analysis method, this research has quantitatively carried out an evaluation of the influence that eight key geometric and physical parameters exert upon maximum collision forces. Our results have shown that the elliptical long axis of recoil chambers is the main parameter that contributes 67.2% to the main effect; what comes next is the elliptical minor axis and linear sections, which have contribution proportions of 17.1% and 10.3% separately. Other parameters have demonstrated influences which can be ignored. The optimization model which is gotten from sensitivity analysis has decreased maximum contact forces by 29.73%, thus its validation errors are under 1% via high-fidelity modeling. This study provides a theoretical basis and efficient analytical tools for structural optimization and impact vibration suppression of turret-mounted guns.

Open Access

Article

Article ID: 4221

Evaluating the impact of tire stiffness on dynamic load in three-wheel trucks

by Nguyen Van Tong Em, Le Phan Trong, Vo Thai Nguyen

Sound & Vibration, Vol.60, No.4, 2026;

The dynamic loads that are produced by the various modes of transportation while they are in motion have a significant impact on the dynamic safety of the bridge or road, as well as the vehicle. Load impacts, which also cause structural damage to transportation infrastructure, are responsible for the catastrophic deterioration of the road and bridge system. In addition to this, it has an effect on the safety of drivers as well as the durability of the components of the vehicle. One of the characteristics that is connected to load is the stiffness of the tire. In this article, the structure of the multi-body system is separated, and the Newton-Euler equation is applied in order to develop the oscillation equation system for the vehicle. The ISO 8608:2016 standard is utilized in order to investigate the impact that varying levels of tire stiffness have on the dynamic load of three-axle vehicles that are driven on class B roads. The findings of the study indicate that the dynamic load on the tire increases in a manner that is proportional to the tire's stiffness at travel speeds. At 90 km/h on a class B road, increasing tire stiffness by 1.5 times raises dynamic load at the front axle from 50,389 N to 50,758 N (1.92%), while reducing stiffness by 0.5 times decreases load to 50,045 N (0.69%). Similarly, rear axle load rises from 46,874 N to 47,626 N (1.64%), indicating tire stiffness's quantitative impact on dynamic load.

Open Access

Article

Article ID: 3977

Co-design of flow architecture and dynamic stability: A multi-objective topology optimization framework for high-performance, low-noise redox flow batteries

by Leila Abdelgader

Sound & Vibration, Vol.60, No.4, 2026;

 This work presents a mathematical framework for the analysis and control of coupled partial differential equations governing transport phenomena in porous vanadium redox flow battery electrodes. The model integrates Brinkman–Forchheimer equations for momentum transport, convection–diffusion–reaction equations for species distribution, and Butler–Volmer kinetics for electrochemical dynamics, forming a strongly coupled nonlinear PDE system with spatially heterogeneous coefficients. Well-posedness of the forward problem is established, and adjoint-based sensitivity analysis is developed for parameter dependence. The core innovation lies in formulating electrode design as an optimal control problem, where the spatially distributed permeability field  serves as the control variable optimized under manufacturing and pressure drop constraints. Using the Method of Moving Asymptotes within a topology optimization framework, biomimetic permeability architectures inspired by vascular networks are synthesized. Bifurcation analysis reveals critical thresholds (, ) where the system transitions from uniform to heterogeneous flow regimes, governing both mass transport efficiency and mechanical stability. Stochastic sensitivity analysis over  parameter variations confirms robust performance with output deviations below . The optimally controlled permeability field achieves a  reduction in concentration variance and a  enhancement in net system efficiency. Extending to flow-induced vibration, frequency-domain forced response analysis shows the optimized distribution suppresses vibration acceleration by  and reduces acoustic emission by  dB(A). This establishes a control-theoretic interpretation: the permeability field functions as an open-loop controller simultaneously optimizing electrochemical performance and passively damping mechanical excitation. The work bridges PDE-constrained optimization, bifurcation theory, and robust control with practical energy storage applications.

Open Access

Article

Article ID: 3848

Research on dynamic characteristics of reinforced concrete supported girder bridges strengthened by plate–truss combination

by Mulin Pang, Wenxin Gou, Xiaoli Xie, Donglin Meng, Feng Cao

Sound & Vibration, Vol.60, No.4, 2026;

Existing strengthening methods for reinforced concrete simply supported girder bridges are predominantly based on local reinforcement, which limits their effectiveness in improving global structural performance. To address this limitation, a novel strengthening approach, namely the Method of Plate–Truss Combination Reinforcement (MPTCR), is proposed to transform the structural force system. In this method, steel trusses and a bridge deck system are integrated with the existing girder through reliable connectors to form a plate–truss composite system (PTCS), thereby enhancing stiffness and redistributing internal forces. An engineering case study is investigated using finite element analysis and field dynamic load testing. The results show that the fundamental frequency increases by 31.5% after strengthening, while the deflection is reduced by 38.2%. The measured fundamental frequency (9.452 Hz) agrees well with the numerical result (8.883 Hz), with a relative error of 6.4%. Moreover, the measured impact coefficients are significantly lower than the code-based value, indicating improved dynamic performance. The findings demonstrate that the proposed method effectively enhances global stiffness, mitigates tensile stress in the original girder, and improves the dynamic behavior of the structure. This study provides a practical and efficient solution for the rehabilitation of aging girder bridges.

Open Access

Article

Article ID: 4256

Adaptive decomposition and energy-frequency characteristics of high-speed railway train vibration signals on the surface of shallow-buried tunnels

by Linli Zhou, Kenan Zheng, Baoxin Jia, Zhiyang Zhou, Sihao Ding

Sound & Vibration, Vol.60, No.4, 2026;

Vibration signals induced by high-speed railway trains on the surface above shallow-buried tunnels exhibit strong non-stationarity and high background noise due to the coupling of tunnel dynamic response and environmental noise. Traditional signal processing methods struggle to extract key wheel-rail vibration components accurately. To solve this issue, this study proposes an adaptive parameter optimization method for variational mode decomposition (VMD), termed SE-SSA-VMD, based on sample entropy (SE) and the sparrow search algorithm (SSA). By intelligently optimizing the mode number K and penalty factor α, the method improves decomposition objectivity and anti-noise robustness. Simulation results confirm that the method achieves accurate effective mode separation with an average center frequency error below 0.2 Hz at a signal-to-noise ratio of 5 dB. Measured data indicate that vibration energy is mainly concentrated in 35–60 Hz with a Gaussian unimodal distribution, and the adjusted R² of over 95% measuring points exceeds 0.8. Higher train speed significantly increases vertical vibration energy, while longer marshalling mainly strengthens lateral vibration energy; both cause a downward shift of the dominant frequency. Far-field vibration energy does not decay monotonically and shows slight local fluctuations, but remains at a low level owing to strong energy dissipation of overlying artificial fill, regardless of initial speed and near-field energy. This work provides an effective approach and theoretical support for vibration assessment and mitigation design in shallow-buried high-speed railway tunnel sections.

Open Access

Article

Article ID: 4268

Lifecycle cost optimization of vibration mitigation in rotating machinery: Integrating measured transmissibility, finite element modeling, and downtime cost scenarios

by Sulieman Ibrahim Mohammad, Naeema Darwish Khamis Al Maashari, Asokan Vasudevan, Wenya Wu, Mohammad Faleh Ahmmad Hunitie, Anber Abraheem Shlash Mohammad, Torki M. Al-Fawwaz

Sound & Vibration, Vol.60, No.4, 2026;

Rotation devices play a vital role in industrial plants, where vibrations significantly affect efficiency, reliability, and the overall cost of operation. Vibrations cause wear and tear, failures, and high maintenance time, but previous studies have focused on machine efficiency without including financial factors. This paper provides a solution to this problem by developing an integrated approach to optimizing lifetime cost through vibration reduction in rotation devices. A numerical approach was used to quantify and analyse the phenomenon, including experimental measurement, finite element (FE) modelling, and economic analysis. Transmissibility measurement was used to describe vibration dynamics and validate the FE model. The response of the system was correlated to wear and tear, failure rates, and downtime. These factors were then used to formulate a lifetime cost model. The results have shown that there is a strong non-linear connection between the transmissibility factor and the lifecycle cost, where the higher the levels of vibrations, the greater the extent of wear and tear and downtime. The process of optimizing identified the optimum operating point where there is a perfect compromise between the vibration performance and the cost effectiveness. The sensitivity analysis has revealed that the transmissibility is the most significant factor affecting the lifecycle cost.

Open Access

Article

Article ID: 3976

Co-design of flow fields and vibration control for vanadium redox batteries

by Jacer  Hamrouni, Leila  Abdelgader, Abdennaceur  Kachouri, Mounir  Baccar

Sound & Vibration, Vol.60, No.4, 2026;

Vanadium redox flow batteries (VRFBs) are promising candidates for grid-scale energy storage, yet their performance and operational reliability remain constrained by conventional flow field designs, such as serpentine and interdigitated architectures, which inherently trade-off between uniform reactant distribution, hydraulic efficiency, and mechanical stability under dynamic fluid loads. While previous optimization efforts have focused separately on electrochemical performance or pressure drop reduction, no integrated framework has addressed the coupled interaction between flow field topology, species transport, and flow-induced vibration, leaving a critical gap in achieving simultaneously high efficiency and long-term structural reliability. This study introduces a bio-inspired, co-design framework that integrates topology optimization, computational fluid dynamics, electrochemical reaction modeling, and structural dynamics analysis to concurrently optimize flow field architecture and mitigate pressure-induced vibration in VRFBs. The methodology employs a density-based optimization approach guided by Murray's Law and leaf venation principles, constrained by pressure drop limits and manufacturability, and validated through both high-fidelity numerical simulations and experimental prototype testing. The optimized biomimetic flow field achieves a 28% increase in volume-averaged reaction rate, a 27.6% reduction in pressure drop at 40 mL min⁻¹, and a 41% reduction in root-mean-square vibration acceleration compared to a conventional interdigitated design. Voltage efficiency improves by 5.2 percentage points, reaching 89.5% at 120 mA cm⁻², while active area utilization increases from 68% to 91%. These results demonstrate that the proposed co-design framework successfully decoupled the traditional trade-off between electrochemical performance and hydraulic-mechanical stability, providing a validated, nature-inspired pathway toward high-performance, reliable energy storage systems that address practical engineering challenges in noise, vibration, and durability.

Open Access

Article

Article ID: 4356

Physics-informed remaining useful life prediction of rolling bearings under variable speed using vibration envelope features and adaptive maintenance thresholds

by Suleiman Ibrahim Mohammad , Asokan Vasudevan, Seif Al Bustanji, Qian Chen , Jin Zhang , Ziyu Cai

Sound & Vibration, Vol.60, No.4, 2026;

The reliable estimation of remaining useful life (RUL) of rolling bearings plays a critical role in maintaining the reliability of modern industrial equipment and minimizing machine downtime. However, the conventional vibration-based prognostic methods tend to experience challenges in predicting the remaining useful life of rolling bearings in variable-speed operating environments due to issues with nonstationary signals and the lack of incorporation of physical degradation processes. This paper proposes a physics-informed approach for estimating the remaining useful life of rolling bearings using vibration envelope characteristics and accelerated life testing. The approach starts with the use of order tracking combined with envelope analysis to extract vibration envelope characteristics under variable speed conditions. A health index is constructed to represent the degradation process. The nonlinear degradation process is modelled using a physics-informed exponential degradation model. An ensemble prediction model is proposed for predicting RUL. The results demonstrate that the developed model was significantly more accurate in its predictions, with a maximum of 49% improvement in the RMSE compared to traditional models and consistent results under varied operational conditions. The use of physics-based modelling and envelope analysis increased the clarity and robustness of the model, and the acceleration of the life testing process contributed to better generalizability of the model. Moreover, the introduction of adaptive threshold values improved maintenance time prediction by over 50%, and uncertainty assessment confirmed the validity of the model.

Open Access

Article

Article ID: 3903

Active sound design and sound field equalization for electric vehicles using an order synthesis algorithm and IIR filter-based correction

by Xueqing Zhang, Jianjiao Deng, Jinliang Bi, Hao Li, Chao Li, Chengpeng Zhang

Sound & Vibration, Vol.60, No.4, 2026;

Active Sound Design (ASD) can enhance the driving experience. At present, the algorithms for synthesizing sound waves have problems of poor robustness and poor sound quality. This study overcomes these problems by introducing a vehicle active sound design order synthesis algorithm that is based on linear interpolation to define a model for the variation of amplitude and frequency with speed. An IIR filter-based sound field equalization and timbre correction method is used to perform frequency-domain correction of four seats in a vehicle to reduce phase interference phenomena. A hardware system based on Field-Programmable Gate Array (FPGA) and Advanced RISC Machines (ARM) was built to configure an electric vehicle sound system. Tone correction, feasibility and stability verification of algorithms, and subjective evaluation of active sound are performed through testing. The Frequency Response Standard Deviation (FRSD) of the four measurement points is used to measure the quality of tone correction, which is improved by 22.9%. The commissioning of the active sound waves based on the hardware system has a frequency response error rate of 5% between the simulated and measured data in the frequency band 0–6,000 Hz. The subjective evaluation of the sound based on four dimensions is used to measure the sound quality and scores 8 points.

Open Access

Article

Article ID: 4292

Possibility-based transfer-matrix optimization of a graded double-cavity micro-perforated partition with fuzzy parameters for broadband sound transmission loss

by Yogeesh Nijalingappa, Naeema Darwish Khamis Al Maashari, Asokan Vasudevan, Chethana N. S., Wenya Wu , Sulieman Ibrahim Mohammad, Mohammad Faleh Ahmmad Hunitie

Sound & Vibration, Vol.60, No.4, 2026;

This study proposes a possibility-based transfer-matrix optimization and assessment framework for fuzzy geometric parameters in a graded double-cavity micro-perforated partition. The system consists of a front limp panel, a first air cavity, a micro-perforated panel, a second air cavity, and a back limp panel. The two cavities are graded over three equal parallel strips, so the local depths of the two cavities differ from strip to strip. Fuzzy numbers model each uncertain design quantity as a triangular fuzzy number and propagate through alpha-cuts. The acoustic model consists of explicit transfer matrices, an area-averaged transmission coefficient, and normal-incidence sound transmission loss. The specific novelty is the direct use of exact alpha-cut corner propagation inside the graded strip-wise transfer-matrix objective, where guaranteed band-average sound transmission loss, guaranteed low-band minimum, and fuzzy width are evaluated together rather than only after a deterministic design is selected. A fuzzy width penalty and guaranteed band-average transmission loss with guaranteed low-band minimum transmission loss are included in the objective function. This is analyzed with a detailed numerical study from 250 Hz to 2,000 Hz. The selected graded design realizes a guaranteed average sound transmission loss of 78.085 dB and a guaranteed low-band minimum of 41.323 dB, while the central design gives 81.425 dB and 43.406 dB, respectively. Compared with a uniform-cavity reference evaluated under the same fuzzy setting, the graded design improves the guaranteed low-band average and minimum while maintaining a comparable uncertainty width. This study focuses on mathematical formulation, tabulated numerical output, and an accessible interpretation of design rather than a long theoretical discussion.

Open Access

Article

Article ID: 4175

Optimization design of fuel tank structure for a certain excavator based on finite element analysis

by Bowen Chen, Peigang Jiao, Guoqing Qi, Yanan Zhang

Sound & Vibration, Vol.60, No.4, 2026;

This study focuses on the fuel tank of a specific excavator model, employing CATIA for modeling and ANSYS Workbench for finite element analysis. Static strength, modal, and random vibration simulations were performed to address stress concentration, excessive deformation, and resonance risks caused by oil sloshing. An optimized design was proposed and experimentally validated. The original fuel tank was first simplified and modeled using Q235 material. A mesh convergence study determined a 10 mm element size, balancing accuracy and computational efficiency. Static analysis confirmed that maximum stress and deformation met material allowables. Modal analysis revealed a first natural frequency of approximately 67.40 Hz, significantly above the frame's excitation frequency of around 10 Hz, effectively avoiding resonance. Random vibration analysis indicated prominent Y-direction deformation and X-direction stress. An optimization scheme was developed: symmetrically lengthening the transverse anti-slosh baffles and adding rounded stiffening ribs at the bottom. Post-optimization, deformations and stresses decreased markedly in all directions, with X-direction stress reduced by over 60%. Bench strain testing agreed with simulation results to within 91%, verifying the reliability and safety of the optimized structure. Results demonstrate that combining anti-slosh baffles with stiffening ribs significantly enhances vibration resistance, reduces fatigue failure risk, and maintains controllable manufacturing processes and costs. This provides a reusable simulation and optimization methodology for lightweight, durable fuel tank design in construction machinery.

Open Access

Article

Article ID: 4376

Analysis and suppression of noise in manual gearbox for military equipment based on acoustic finite element simulation

by Tengyue Pan, Xinmin Shen, Wenqiang Peng, Jiaojiao Zhang, Xiaocui Yang, Chengming Jiang

Sound & Vibration, Vol.60, No.4, 2026;

To improve the acoustic stealth performance of military equipment, it is essential to analyze and suppress the radiation noise of the manual gearbox as a critical unit. Based on a three-dimensional model of a 5-speed synchromesh gearbox and analysis of its operating principle, the vibration characteristics are studied using multibody dynamics. The housing vibration obtained from the multibody simulation is then used as the acoustic boundary condition in a coupled acoustic-structural finite element simulation to compute the sound pressure level (SPL) of the radiated noise. Taking the SPL at microphones placed around the gearbox as the evaluation indicator, parametric analysis of gear level, input speed, and external load is conducted, and the feasibility of noise control using sound absorbing materials is verified. The results show that the SPL of radiated noise differs significantly in both frequency and spatial domains, and that gear level is the major influencing factor. The total average SPLs for the five gear levels are 137.91 dB, 134.11 dB, 131.83 dB, 124.86 dB, and 81.29 dB, respectively. Moreover, the noise suppression effect of the sound absorbing layer has directionality: the total average SPL at microphone positions M01/M09 is reduced from 139.96 dB to 122.75 dB for the third gear, and from 91.68 dB to 74.55 dB for the fifth gear.

Open Access

Article

Article ID: 4302

Hybrid analytical–numerical–experimental study of low-frequency transformer noise control using stacked Helmholtz resonator panels

by Suleiman Ibrahim Mohammad, Naeema Darwish Khamis Al Maashari, Asokan Vasudevan, Wenya Wu, Mohammad Faleh Ahmmad Hunitie, Anber Abraheem Shlash Mohammad, Torki M. Al-Fawwaz

Sound & Vibration, Vol.60, No.4, 2026;

Low frequency noise produced by electrical transformers is one of the most resilient problems, since such types of noises are highly resistant to standard techniques of noise suppression. Absorption panels do not provide sufficient protection below 500 Hz; hence, alternative techniques based on resonance have been developed in the field of passive acoustic control. This research considers stacked Helmholtz resonators as a possible method of attenuating low frequency noises produced by transformer equipment in the range from 20 Hz to 500 Hz. A combination of analytical, numerical, and experimental techniques is utilized to estimate the effectiveness of the proposed method. Experimental tests have shown that proper configuration of Helmholtz resonators can help to attenuate sounds up to 7.5 dB and provide 9.2 dB of transmission loss. The highest efficiency of attenuation has been estimated at 11.5%. Numerical estimates demonstrated a high level of correspondence with experiments, with an error margin of smaller than 3.2% for all tested configurations. An increase in the volume of cavities, neck lengths, and layering significantly increased the efficiency of low frequency attenuation. It can be concluded that the application of stacked Helmholtz resonator panels is one of the most energy-efficient ways to suppress noise in the considered low-frequency band.

Open Access

Article

Article ID: 1707

A Raspberry Pi-based digital stethoscope: Advancing real-time heart and lung sound diagnostics with IoT and machine learning integration

by Nurul Azwaani Salehuddin Haqe, R Kanesaraj Ramasamy, Sivasutha Thanjappan, Shamsuriani Md Jamal, Faizal Amri Hamzah, Venushini Rajendran

Sound & Vibration, Vol.60, No.4, 2026;

Digital transformation is reshaping auscultation by moving the stethoscope from a purely acoustic instrument to an intelligent, data-driven diagnostic platform. This review critically examines Raspberry Pi 3-based digital stethoscope technologies for heart and lung sound monitoring, with an emphasis on system architecture, sensor integration, signal acquisition, real-time processing, storage, playback, and connectivity. The paper synthesizes current designs and implementation strategies, highlighting how low-cost embedded platforms can improve the repeatability, accessibility, and objectivity of cardiopulmonary assessment compared with conventional acoustic stethoscopes. Particular attention is given to technical performance factors, including filtering, signal-to-noise ratio, latency, audio distortion, noise suppression, and time-frequency analysis, which are essential for detecting clinically significant acoustic features such as heart murmurs, crackles, and wheezes. The review also identifies key limitations affecting clinical translation, including power consumption, device portability, casing size, environmental noise, hardware constraints, and the need for robust validation in real-world settings. Future directions include optimized embedded processing, wireless and IoT-enabled tele-auscultation, cloud-assisted data management, and machine learning models for automated classification and decision support. Overall, Raspberry Pi 3-based digital stethoscopes represent a promising pathway toward affordable, scalable, and clinically meaningful cardiopulmonary monitoring, particularly for point-of-care, remote, and resource-limited healthcare environments. By integrating acoustic sensing, edge computing, and intelligent analytics, these systems can strengthen diagnostic workflows and support the next generation of connected digital healthcare.

Open Access

Article

Article ID: 4154

Study on influencing factors of ultrasonic testing for lead seal defects in high-voltage cables

by Peng He, Jian Cheng, Fengyin Zhang, Lianbing Wang, Cen Qian

Sound & Vibration, Vol.60, No.4, 2026;

Lead seals are critical sealing and protective components of high-voltage cable terminations, and their structural integrity directly determines the safe and stable operation of urban power transmission systems. Conventional non-destructive testing methods face inherent limitations such as low penetration depth and susceptibility to heat-shrinkable protective layers, making ultrasonic phased array technology a promising alternative for lead-seal defect detection. However, imaging quality is often severely degraded by practical factors encountered in complex field inspection environments. This study systematically investigates the effects of coupling condition, surface roughness, and surface curvature on ultrasonic imaging performance for lead-seal defects. Three groups of controlled comparative experiments were conducted using artificially fabricated lead-seal specimens with predefined internal defects, varying surface roughness levels, and different curvature radii. A dedicated ultrasonic phased array testing platform equipped with a 5 MHz, 16-element probe was established to quantitatively evaluate imaging quality through metrics including signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and bottom-wave amplitude. The results show that the improved flexible film coupling device provides significantly better imaging quality than the conventional rigid wedge, with 28.5% higher SNR and 27.8% higher CNR. In addition, increased surface roughness enhances diffuse reflection and reduces echo coherence, while surface curvature introduces spatial phase deviations that weaken bottom-wave response and increase defect interpretation difficulty. These findings provide essential experimental evidence and practical guidance for optimizing field inspection protocols and improving the reliability of ultrasonic testing for high-voltage cable lead seals.

Open Access

Article

Article ID: 4280

Nonlinear sloshing dynamics in rigid cylindrical shells under combined horizontal and vertical excitation

by Elena Strelnikova, Andrii Rusanov, Vasyl Gnitko, Kyrylo Degtyariov, Denys Kriutchenko, Andrii Kolodiazhnyi, Demyd Sinchenko

Sound & Vibration, Vol.60, No.4, 2026;

This paper presents the theoretical foundations for the nonlinear modelling of liquid sloshing dynamics in shells of revolution subjected to combined horizontal and vertical excitations. The proposed mathematical model integrates a spectral approach, the boundary element method (BEM), and a modal representation of the solution in generalized coordinates. This unified framework enables consistent analysis of both linear and nonlinear sloshing phenomena. The spectral boundary-value problem is reduced to a system of singular integral equations defined on the free and wetted surfaces of the shell. The 2π-periodicity of the integral operators is rigorously established, and the structure of the kernel singularities is identified. This ensures mathematical consistency and supports efficient numerical implementation. Natural sloshing modes and frequencies are computed using a BEM-based solver. Based on these eigenmodes, a modal expansion is constructed, leading to reduced-order systems of nonlinear ordinary differential equations. Governing equations are derived for both linear and nonlinear formulations, allowing detailed investigation of sloshing responses under simultaneous horizontal and vertical excitations. Rayleigh damping is incorporated into the modal system; its applicability and physical justification are discussed, along with its limitations in capturing energy dissipation in violent sloshing processes. Numerical results for rigid cylindrical shells illustrate the significant influence of nonlinear modal interactions and combined loading on free-surface elevation. The developed approach provides an effective tool for predicting complex sloshing behaviour beyond the capabilities of purely linear theory.

Open Access

Article

Article ID: 4311

Optimal design of a high-temperature ultrasonic vibration device

by Lanphuong Nguyen, Chinghua Hung

Sound & Vibration, Vol.60, No.4, 2026;

Ultrasonic vibration-assisted manufacturing has emerged as a transformative method for machining hard-to-machine advanced materials. However, implementing these systems in precision high-temperature manufacturing processes like hot glass embossing introduces significant technical challenges due to severe thermal frequency drift and a degradation in output displacement uniformity. This study addresses these issues by presenting a comprehensive multi-physics numerical optimization framework for a 35 kHz high-temperature ultrasonic vibration device. Utilizing a coupled-field Finite Element Analysis (FEA) methodology in ANSYS, the steady-state thermal profile and its corresponding thermo-structural impact on the system’s resonant frequencies and vibration characteristics were accurately modeled and verified. Shape optimization was executed through an automated coupling loop between the FEA workspace and the advanced numerical optimization platform, SmartDO. The results demonstrate that the optimization scheme successfully established a refined horn geometry that accommodates thermal degradation effects. Experimental validation conducted at an operating temperature of 500 °C confirmed that the optimized design maintained structural deviations within a narrow, manageable resonance window (84–99 Hz) while significantly improving output surface displacement distribution. The finalized device achieved an exceptional experimental amplitude uniformity of 8.20%, which matches the numerical simulation trend closely.

Open Access

Article

Article ID: 4010

Fuzzy–chaotic modelling for nonlinear vibration systems under parameter uncertainty

by Asokan Vasudevan, Yogeesh Nijalingappa, Soon Eu Hui, Zetty Pakir Mastan, Choo Wou Onn, Mohammed El Khider

Sound & Vibration, Vol.60, No.4, 2026;

Chaotic responses arise in many nonlinear dynamical systems and can strongly influence practical engineering decisions when measurements, parameters, or operating conditions are imprecise. This paper presents a vibration-oriented fuzzy-parameter uncertainty framework in which uncertain parameters and initial conditions are represented by fuzzy numbers and propagated through a Lorenz-type nonlinear model by means of α-cuts. The novelty claimed here is not the introduction of fuzzy uncertainty itself, but the use of a single workflow that links α-cut propagation, response envelopes, and the interpretation of chaos-sensitive indicators for uncertainty-aware nonlinear vibration analysis. Conventional dynamical descriptors such as phase portraits, stability trends, and bifurcation-related behavior are therefore interpreted as bounded families of trajectories rather than as a single deterministic path. A numerical workflow based on standard time integration is outlined to generate response envelopes that quantify the sensitivity of the dynamics to imprecise inputs. As a basic consistency check, the framework reduces to the classical deterministic model when the fuzzy spreads vanish. The approach provides a mathematically tractable route to uncertainty-aware nonlinear dynamics, with clear relevance to vibration and noise engineering, where nonlinear oscillators, self-excited responses, and test-data uncertainty often coexist. Practical considerations for calibration and validation are also summarized.

Open Access

Article

Article ID: 3979

A synergistic framework for high-fidelity redox flow battery design: Integrating biomimetic flow optimization, structural dynamics analysis, and experimental vibration mitigation

by Leila  Abdelgader

Sound & Vibration, Vol.60, No.4, 2026;

This study presents an integrated multiphysics framework for the co-design of flow field architectures in redox flow batteries, aiming to simultaneously optimize electrochemical performance and structural acoustic reliability. A high-fidelity numerical methodology is developed to couple electrolyte hydrodynamics, species transport, electrochemical kinetics, and flow-induced structural vibration, enabling a comprehensive assessment of both electrochemical and mechanical behavior. To overcome the trade-off between mass transfer uniformity and flow-induced noise, the framework employs biomimetically inspired channel topologies—derived from natural fluid transport systems—that enhance homogeneity of species distribution while inherently suppressing flow-induced vibration and acoustic emissions. As a result, both electrochemical polarization and mechanical excitation are reduced. The proposed designs are validated through comparative computational fluid dynamics (CFD) and structural dynamics analyses. Results demonstrate measurable gains in round-trip efficiency, reduced pumping losses, and improved operational stability compared to conventional flow field configurations. By bridging biomimetic fluidic design with rigorous dynamic structural analysis, this work provides an analytically sound and experimentally viable pathway toward next-generation grid-scale energy storage systems that are not only efficient and durable but also operate quietly with reduced mechanical fatigue. The framework thus addresses critical barriers to the widespread deployment of redox flow batteries, particularly in noise-sensitive or vibration-prone environments.

Open Access

Article

Article ID: 4135

Research on fatigue life calculation method of droppers in high-speed railway catenary

by Hongbo Kou, Yongming Yao, Haoshu Lu, Yunqian Ma

Sound & Vibration, Vol.60, No.4, 2026;

To address the problems that catenary droppers are prone to fatigue failure under the operating environment of high-speed trains and are faced with the shortage of load measurement samples, insufficient extrapolation accuracy, and large dispersion in life evaluation, an optimized fatigue load extrapolation method based on small multiples and multiple iterations is proposed. Firstly, a pantograph-catenary coupling system model is established. After verification, the load-time history of the dropper is obtained through dynamic simulation. Secondly, the rainflow counting method is used to statistically analyze the stress cycles. The bandwidth and range of non-parametric rainflow extrapolation are determined according to the extrapolation multiple, and the reliable load extrapolation to the target multiple is realized through a multi-iteration strategy, which is compared with the traditional amplification method and the large-multiple direct extrapolation method. Finally, the mean stress is corrected based on the Goodman model, and a standard fatigue load spectrum is constructed. Combined with the S-N curve and linear cumulative damage theory, a fatigue life prediction model for high-speed railway droppers is established. This study provides a theoretical basis and data support for life evaluation, maintenance schedule formulation, and reliability design of catenary droppers.

Open Access

Article

Article ID: 4065

Robust speech denoising using a parallel target-field non-causal WaveNet under stationary and non-stationary noise

by Jella Sandhya, Shafiq Ul Rehman, Shaik Mazhar Hussain

Sound & Vibration, Vol.60, No.4, 2026;

The presence of stationary or non-stationary noise substantially impairs speech intelligibility and its perceptual quality in present-day communication systems. Many existing spectral-domain methods like Wiener filtering and spectral subtraction rely on strong statistical assumptions about complex-valued data, while state-of-the-art neural models such as Conv-TasNet, DCCRN, and MetricGAN+ achieve remarkable performance gains for speech enhancement, but tend to suffer from heavy computational complexity and inference latency due to their complex architecture. In this paper, we present a new supervised non-causal WaveNet with parallel target-field prediction for efficient end-to-end speech denoising. The proposed model captures both past and future temporal context by enabling symmetric receptive fields and removing autoregressive dependencies. Traditional autoregressive WaveNet models generate samples one at a time, which require considerable redundant convolution operations due to the repetitive nature of their structures and tasks, while the presented method is capable of predicting a target field of samples in a single forward pass, allowing for parallel inference. We validate the proposed model on the NSDTSEA dataset for input SNR levels of 2.5 dB to 17.5 dB and under stationary as well as non-stationary noise types. We showcase experimental results that prove that the proposed framework consistently outperforms strong classical baselines, with over 1.22 dB gain in output SNR and 46% reduction in Mel Cepstral Distortion (MCD) under non-stationary noise. Moreover, when compared to state-of-the-art deep learning models such as Conv-TasNet, DCCRN, and MetricGAN+, the proposed method achieves a viable trade-off between performance, robustness, and computational efficiency.

Open Access

Article

Article ID: 4206

The analysis of vibration characteristics of rotor system with delay effects

by Yue Zhang, Zhihui Xue, Yuejuan Yang, Yangyang Yu, Guoying Pang

Sound & Vibration, Vol.60, No.4, 2026;

The rotor system, as the core component of rotating machinery, its dynamic characteristics directly affect the safe and stable operation of the equipment. The seal components ensure the sealing performance of the system, but the unsteady flow of gas in the sealing gap will induce delay-type nonlinear seal forces and affect the vibration characteristics. This paper studies the vibration characteristics of rotor systems with delay effects. Firstly, the complexity of the sealing structure causes air flow disturbances, resulting in displacement delay feedback excitation. Therefore, the rotor system dynamic model containing displacement delay feedback is established. Secondly, the stability operating boundaries are derived based on the eigenvalue analysis method, revealing the influence mechanism of delay parameters on the steady-state operation. It is obtained that the stability boundary undergoes periodic migration under the combined effect of delay and feedback intensity. Finally, the accuracy of the proposed model is verified through numerical simulation. The research shows that time delay induces nonlinear vibration characteristics. At a rotational speed of 1,000 rad/s, the time delay exceeding 0.24 s drives the system into a chaotic operating state, which is detrimental to stable operation. Furthermore, the value of the seal parameter  significantly affects the operating state of the rotor system. This work provides a theoretical basis for the dynamic modeling, stability analysis, and vibration control of rotor systems with delay effects, and has engineering significance for the reliable operation of high-speed rotating machinery.

Open Access

Article

Article ID: 4262

Co-design of mechanical and electrical parameters in wind turbine gearbox-generator systems

by Ruibo Chen, Zhonghua Wu, Jinwei Sun, Datong Qin, Chuanwei Zhao

Sound & Vibration, Vol.60, No.4, 2026;

Conventional design practices for wind turbine drivetrains commonly adopt a segregated workflow where the gearbox and electrical machine are developed independently. Such a decoupled strategy overlooks inherent electromechanical coupling constraints, thereby imposing fundamental limits on attainable power density and dynamic behavior of the entire transmission assembly. To mitigate these limitations, this work presents a hierarchical integrated parameter co-design framework for wind turbine gearbox–generator systems, which implements progressive optimization from system-level to component-level, while synchronously satisfying static performance and dynamic response requirements. In the first design stage, an integrated initial parameterization scheme is formulated via finite element analysis (FEA) and numerical computation, with objectives to elevate system power density and suppress amplitudes of internal dynamic excitations. The optimized parameters from this stage serve as baseline inputs for the second stage. An electromechanically coupled dynamic model is then established to quantify correlations between key mechanical structural parameters (gearbox bearings, hollow shafts, splines, ring gear bolt stiffness) and generator electromagnetic/structural parameters, as well as overall system dynamic characteristics. Sensitive design variables are identified via correlation analysis, and a Kriging surrogate model is constructed to approximate nonlinear input–output relationships efficiently. Multi-objective component optimization is subsequently performed using the surrogate model. Finally, vibration attenuation and load reduction performances of the baseline and optimized drivetrain configurations are systematically compared under rated and variable operating conditions.

Open Access

Article

Article ID: 4263

Tower dynamic response analysis of wind turbines during primary frequency regulation

by Yingwei Wang, Aolin Song, Tingxiang Zhang, Yilin Du

Sound & Vibration, Vol.60, No.4, 2026;

As wind turbines increasingly participate in Primary Frequency Regulation (PFR) to support grid frequency stability, the accompanying mechanical load variations pose a potential threat to structural reliability. However, the underlying aero-electro-mechanical coupling mechanisms by which PFR-induced power and torque fluctuations affect tower dynamics have not been fully clarified. This study develops a multidimensional analytical model of a wind turbine with PFR to reveal the transmission path from grid frequency deviations to generator torque variations and subsequently to tower side-to-side (SS) bending moments. Frequency-domain and time-domain analyses show that generator torque, rather than aerodynamic thrust, is the dominant excitation source for tower SS vibration during PFR. The results further indicate that this excitation is highly phase-sensitive: the amplification or suppression of tower vibration depends on the instantaneous phase alignment between the torque disturbance and the tower’s natural sway cycle. Therefore, identical PFR commands may lead to substantially different structural responses when activated at different instants. The analytical conclusions are validated using high-fidelity FAST co-simulations under stochastic wind and grid-disturbance scenarios. Quantitative fatigue evaluation shows that uncoordinated PFR may increase the tower SS Damage Equivalent Load (DEL) by up to 600% in low-wind-speed regimes. These findings demonstrate that future wind turbine PFR controllers should incorporate phase-aware coordination strategies to reduce structural resonance and fatigue risks while maintaining effective grid frequency support.

Open Access

Article

Article ID: 4345

Influence of spruce guitar resonance panel structure on acoustic vibration response characteristics

by Guanzheng Wan, Jinyi Chen, Yihang Ben, Siyuan Wang, Liang Zhang, Lan He, Yuanji Zhao, Haotian Cui, Zhenbo Liu

Sound & Vibration, Vol.60, No.4, 2026;

In recent years, the guitar manufacturing industry has faced a growing shortage of large-diameter, high-quality spruce wood resources. To address this issue, it is urgently necessary to conduct research on the structural design of guitar resonance panels. This study investigates three types of spruce guitar resonance panels with different structures, exciting them at various points, and using a multi-channel FFT analyzer to capture vibration signals and analyze their acoustic vibration response characteristics. The results show that in terms of root mean square (RMS) values indicating overall signal intensity and peak-to-peak values reflecting signal amplitude, the double-spliced resonance panel exhibits the highest vibration energy, followed by the quadruple-spliced resonance panel, while the triple-spliced resonance panel shows the lowest. Regarding spectral centroid and high-frequency energy—indicating richness of high-frequency content—and spectral flatness and kurtosis—reflecting uniformity of energy distribution—the triple-spliced resonance panel demonstrates the brightest tonal quality and the most even spectral energy distribution, followed by the quadruple-spliced panel. From raw material to finished panel, and from double-spliced to quadruple-spliced panels, both elastic modulus and shear modulus show an increasing trend. Compared to the double-spliced panel, multi-spliced panels exhibit higher specific dynamic elastic modulus and acoustic impedance, but lower acoustic radiation quality constant. Although individual parameters vary to some extent, the overall acoustic vibration performance of multi-spliced panels differs little from that of the double-spliced panel. These findings not only provide practical guidance for manufacturers but also offer theoretical support for improving the acoustic quality of guitars.

Open Access

Article

Article ID: 4222

System vibration characteristics and fault evolution evaluation based on multimodal data fusion

by Shasha Li, Wenjing Kong, Tiejun Cui

Sound & Vibration, Vol.60, No.4, 2026;

To address the problems of one-sided modal information, unclear fault evolution, and insufficient support for early fault diagnosis warning of complex systems, a method for evaluating system vibration characteristics and fault evolution based on multimodal data fusion is proposed. With multimodal data fusion, factor space mapping, fault evolution network modeling, and probabilistic evaluation as the core, the unified characterization of heterogeneous data to fault-influencing factors is realized through feature extraction and hierarchical mapping of multi-source data, including vibration, acoustic emission, and oil analysis. Based on the Space Fault Network (SFN), the topological relationship and probability transfer model of fault events are constructed. Combined with evolutionary entropy analysis, an evaluation system of failure probability-evolutionary entropy and a hierarchical early warning mechanism are formed. Taking the axle box bearing as an example, with thresholds determined by full-life cycle fault data fitting and engineering experience, the system fault is identified as the attention state at 80 hours and the high-risk state at 100 hours, which is consistent with the law of gradual fault evolution and engineering practicability. The proposed method forms a failure probability–evolutionary entropy dual-index evaluation system and a hierarchical early warning mechanism with strong physical interpretability, providing reliable technical support for reliability evaluation and predictive maintenance of complex mechanical systems.

(This article belongs to the Special Issue Vibration and System Fault Analysis)

Open Access

Review

Article ID: 4444

From track to stability: A review of vibration behavior, structural reliability, and dynamic performance in railway vehicles

by Yana Li, Yunxiao Chen

Sound & Vibration, Vol.60, No.4, 2026;

Railway vehicles operate under continuously changing wheel-rail contact, track geometry, loading, speed, and environmental conditions, making vibration behavior a direct driver of ride comfort, running safety, structural fatigue, and maintenance demand. Existing studies often examine vehicle vibration, structural reliability, and dynamic performance separately, which can obscure the causal path from track excitation to vehicle response, fatigue damage, performance degradation, and maintenance action. This review synthesizes these topics within an integrated life-cycle framework. It first examines major vibration excitation mechanisms, including track irregularities, wheel and rail defects, turnouts, transition zones, traction and braking forces, and aerodynamic disturbances. It then reviews modeling and analysis methods, including multibody dynamics, finite element analysis, vehicle–track coupled models, co-simulation, monitoring-based validation, and uncertainty analysis, with emphasis on their ability to connect dynamic loads with stress histories and fatigue reliability. Structural reliability is discussed as the mechanism by which vibration-induced loads become service risk, while dynamic performance is evaluated through ride comfort, running safety, hunting stability, vibration control, and multi-objective optimization. Furthermore, key limitations such as simplified contact assumptions, insufficient full-scale validation, weak coupling between monitoring data and fatigue models, limited interpretability of AI diagnosis and immature digital-twin implementation are identified in this review. Finally, future directions are proposed toward physics-informed modeling, uncertainty-aware reliability assessment, intelligent monitoring, adaptive vibration control and reliability-centered maintenance for safer, more durable, and sustainable railway vehicles.