https://jvs.isav.ir/ Journal of Vibration and Sound en daily 1 Sun, 23 Aug 2026 00:00:00 +0330 Sun, 23 Aug 2026 00:00:00 +0330 https://jvs.isav.ir/article_736961.html Human activities in marine areas-particularly pile-driving operations and other industrial processes associated with the construction and operation of refineries-generate intense underwater sound sources that can exert significant impacts on marine habitats and aquatic species. The Persian Gulf, as a geographically and economically critical region for Iran, has not yet been subjected to a comprehensive soundscape assessment, and adequate information on the intensity and distribution of these acoustic sources in the country’s aquatic environments is lacking. This review article aims to introduce pile driving as a major anthropogenic sound source in the Persian Gulf and to examine its potential implications for the sustainability of marine ecosystems. The study underscores the importance of conducting systematic soundscape investigations in Iranian waters, especially in the Persian Gulf. Insufficient knowledge of anthropogenic acoustic profiles may hinder effective management and conservation of sensitive aquatic species. Ultimately, the paper emphasizes the urgent need for field-based surveys, frequency-domain acoustic analyses, and environmental impact assessments to inform the development of more effective conservation policies for this marine region. https://jvs.isav.ir/article_738336.html Vibration energy harvesting is one of the emerging approaches for supplying power to low‑power systems and has attracted considerable attention from researchers in recent years. In this study, vibration energy harvesting from a rotating circular plate equipped with a piezoelectric patch is investigated. The governing equations of the plate vibrations are derived by considering the effects of centrifugal force and electromechanical coupling, and the natural frequencies, generated voltage, and electrical power are analyzed. The equations are solved using the Generalized Differential Quadrature Method (GDQM), and the effects of parameters such as the size and thickness of the piezoelectric patch, its installation position, and the disk dimensions on the system performance are examined. The results indicate that the rotation of the plate has a significant influence on the dynamic characteristics and the harvested power. The maximum generated power density is obtained as approximately 3.45 μW/mm³. Finally, for validation purposes, the natural frequencies and system response are compared with finite element simulation results obtained using COMSOL software, showing good agreement. https://jvs.isav.ir/article_737156.html In this study, an algorithm for estimation vertical sound velocity profiles in water bodies based on acoustic tomography technology has been developed. Field measurements at the Letyan Dam have been used to demonstrate the performance of this algorithm. The algorithm for generating continuous sound velocity profiles in water bodies depth was developed based on ray tracing methods and inverse problem solving based on the adjusted Tikhonov method. Acoustic tomography data were collected in the Letyan Dam reservoir for approximately 24 hours and sound velocity was calculated in 5 separate vertical layers with a thickness of 7 meters. For accuracy assessment, the difference in sound velocity using acoustic tomography is examined by CTD data, with the lowest difference observed in the bottom layer of the reservoir (0.88 m/s) and the highest difference observed in the layered level (6.41 m/s). The results showed that the acoustic tomography technology, using the developed algorithm, is capable of estimation of the speed of sound at depth in deep water areas with acceptable accuracy for operational applications in acoustics. https://jvs.isav.ir/article_738784.html Leakage in buried water pipelines leads to increased water losses and reduced efficiency in distribution networks. Considering the limitations of surface and groundwater resources, specific geographical and climatic conditions, and the aging of urban water distribution systems, the issue of water leakage and its associated problems is becoming increasingly significant, especially within water supply networks. Moreover, the use of non-standard pipes and fittings further complicates leak control and detection. Consequently, the adoption of various methods for identifying and controlling water leakage has gained considerable importance. Today, advancements in science and technology allow for precise leak detection without the need for costly and time-consuming excavations, and without relying on visible surface indications. In many developed countries, online leak detection systems are employed as effective tools for managing water losses. Therefore, the performance and efficiency of these devices, which incorporate the latest global technologies, have been investigated and evaluated. In this study, leakage detection methods for pipe–soil systems are reviewed and compared. The findings highlight the necessity of selecting an appropriate leak detection technique based on the physical characteristics of the network. https://jvs.isav.ir/article_739059.html The acoustic quality of assembly halls is a key feature in the architectural design of such spaces. This challenge has long been a concern for architects of religious buildings. Due to the extensive mirror cladding covering the porticos of the Imam Reza (AS) Holy Shrine, designing a sound system for religious ceremonies in this space presents serious challenges and is highly complex. The Imam Khomeini (RA) Portico within the Imam Reza (AS) Holy Shrine is an acoustically highly complex environment, and given its special status in hosting programs at the Holy Shrine, conducting scientific research on its acoustic conditions is of great importance. In this study, an attempt has been made to first describe the acoustic conditions of the Imam Khomeini (RA) Portico, and then, based on simulation results, propose acoustic modifications to improve the existing conditions. Based on simulation results and field measurements, recommendations such as installing sound absorbers on side walls and behind the ceremony platform, as well as creating side corridors using decorative and sound-absorbing walls, were proposed, some of which were implemented. These modifications led to an improvement in the Speech Transmission Index (STI) from below 0.4 to approximately 0.6, and a reduction in reverberation time from about 10 seconds at frequencies below 500 Hz to less than 2.5 seconds—which is considered favorable for a hall with an approximate volume of over 60,000 m³ and fully mirrored surfaces. https://jvs.isav.ir/article_740957.html Unwanted mechanical vibrations at low frequencies, particularly in sensitive systems with space constraints, constitute one of the major challenges in vibration engineering. In this study, a vibration isolator exhibiting quasi-zero-stiffness (QZS) behavior is designed and analyzed. The proposed unit cell consists of a positive-stiffness element based on an eye-shaped geometry combined with initially curved beams acting as negative-stiffness elements. Unlike many conventional multi-component configurations, this integrated design is developed to reduce the required installation space while enabling adjustment of the mechanical response through variations in geometric parameters. Nonlinear static analysis performed in COMSOL shows that this geometric combination creates a region of near-zero effective stiffness in the vicinity of the equilibrium point. Furthermore, numerical investigation of the system’s dynamic response indicates a significant reduction in vibration transmission within the low-frequency range. The numerical results demonstrate that the proposed structure, while maintaining static stability, provides tunable isolation performance through variations in geometric parameters and can therefore be considered a suitable option for applications with limited installation space. https://jvs.isav.ir/article_741087.html This study presents the design, fabrication, and evaluation of a macro-scale atomic force microscope (AFM) aimed at providing a low-cost platform for educational and research applications. Unlike conventional atomic force microscopes, the proposed system does not employ a piezoelectric actuator or an optical sensor. Instead, simultaneous self-sensing and self-actuation are achieved through the interaction between a moving magnet and a coil based on the Hall effect. In this system, a cantilever beam, coil, and magnet are employed to generate and control the beam vibrations in amplitude-modulation mode. The mechanical and electromagnetic components of the system are designed using numerical analysis and simulation, followed by fabrication of a laboratory-scale prototype. After dynamic characterization of the system, an integral controller is implemented on an Arduino development board. The developed microscope is then calibrated using a reference sample, and its performance is evaluated through surface topography imaging. The results demonstrate that the microscope can detect surface variations with a lateral resolution of 1.1 mm and a vertical resolution of 0.2 mm. The findings indicate that, despite its low fabrication cost and simple structure, the proposed system provides a suitable platform for educational purposes, development of control methods, and further improvement of future generations of atomic force microscopes. https://jvs.isav.ir/article_739060.html In this study, vibrations of two bolted flange-connected cylindrical shells are investigated based on three-dimensional elasticity theory. In the semi-analytical model, a set of artificial linear springs—along longitudinal, circumferential, and radial directions—is placed between each pair of grid points employed in the generalized differential quadrature method, which are located on the corresponding flange surfaces. These springs are updated using a genetic optimization algorithm. The primary structure is modeled by dividing it into several shells and assembling them through direct imposition of displacement and stress continuity conditions. In addition, finite element simulations of bolted connections and experimental modal tests are developed to examine vibrational behavior more accurately. Modal analysis in finite element software is inherently linear. Thus, to simulate connections, static analysis results—including stresses from pre-tension torque, deformations, and changes in contact configuration—are used as initial conditions in the modal analysis, enabling simulation of mode shapes of the bolted structure. Natural frequencies obtained from the semi-analytical method, experimental modal testing, and finite element analysis are compared for two connection cases with ten and twenty bolts. The proposed model simulates vibrations of an ideally fabricated bolted flanged cylinder according to the presented procedure with satisfactory precision. However, alternative flange manufacturing methods that may introduce thermal residual stresses or modify mechanical properties warrant separate investigation https://jvs.isav.ir/article_741485.html This study presents an experimental and numerical investigation into the vibrational response of 3D-printed sandwich beams with three distinct core topologies: triangular, honeycomb, and a hybrid configuration combining both. The primary objective is to assess the influence of core topology on natural frequencies and modal damping ratios as key dynamic performance indicators. Specimens were fabricated using Fused Deposition Modeling (FDM) with Polylactic Acid (PLA) material, and impact hammer modal testing was conducted to extract the Frequency Response Functions (FRFs). Natural frequencies and damping ratios were subsequently derived using frequency-domain curve-fitting algorithms. For numerical simulations, a finite element model was developed in Abaqus and validated against the experimental data, yielding a relative error of less than 5%. The findings reveal that the hybrid core, despite having a nearly identical weight, consistently delivers the highest natural frequencies across all bending modes. Modal damping analysis indicates that while the honeycomb core exhibits superior energy dissipation behavior in the first mode, the hybrid core demonstrates a remarkable surge in damping at higher modes (fourth and fifth), which is attributed to the synergistic energy loss effects at the interface between the dissimilar topologies. The outcomes of this research confirm that the application of hybrid cores constitutes an efficient strategy for frequency spectrum engineering and damping control in lightweight sandwich structures. https://jvs.isav.ir/article_741896.html In this study, the performance of an acoustic metamaterial based on a membrane-coupled dual-Helmholtz resonator is investigated. This metamaterial has the potential to be applied in domains such as ventilation systems or household appliances, such as vacuum cleaners. A key feature of the proposed structure is that it attenuates sound without posing an obstruction to the airflow path. The main innovation of this research lies in investigating the direct correlation between the membrane mode shape, the volume variation of the Helmholtz resonator cavity, and the generation of sound transmission loss (STL) peaks within a dual-Helmholtz coupled membrane structure. Simulations were carried out using COMSOL software in two stages, consisting of a simplified model followed by a unit layer of the proposed structure. The results demonstrated that the peaks in the transmission loss curve predominantly occur at mode frequencies where the deformation of the membrane induces a volume change in the Helmholtz cavity; three effective modes of this type were identified in the simplified model, and five in the proposed structure. The frequency discrepancies between the STL peaks and their corresponding eigenfrequencies across the two stages were approximately 2% and 1.5%, respectively. Furthermore, calculating 55 eigenfrequencies in the range of 0 to 2000 Hz took 9 seconds, whereas the frequency-domain analysis with a 1 Hz step required approximately 630 seconds. Consequently, the eigenfrequency analysis provided acceptable accuracy for the targeted identification of sound transmission loss peaks while reducing computation time by roughly 70-fold. https://jvs.isav.ir/article_741837.html Aerodynamic noise generated by industrial fans and blowers remains a significant challenge in ventilation and cooling systems. Inspired by the silent-flight capability of owls, this study proposes and experimentally evaluates a novel non-uniform serrated blade modification for aeroacoustic noise reduction in a five-bladed blower. Unlike previous investigations that primarily employed uniform serration geometries, the present design adopts a physics-based biomimetic approach in which the serration dimensions vary along the blade span according to the distribution of vortex intensity identified in previous aerodynamic studies. This strategy aims to target dominant noise-generating regions and improve the effectiveness of passive flow control. The proposed zigzag attachments were installed separately on the leading and trailing edges of the blower blades, and acoustic measurements were conducted in an anechoic chamber in accordance with ISO 3745. The results showed that the leading-edge serration reduced the overall sound pressure level (OASPL) by 1.61 dB, with a maximum local reduction of 14 dB at 2 kHz. The trailing-edge configuration achieved a larger OASPL reduction of 2.58 dB and a maximum attenuation of 15 dB at 150 Hz. These improvements are attributed to the suppression of dominant vortex structures and the reduction of turbulent pressure fluctuations responsible for aeroacoustic noise generation. The findings demonstrate that combining biomimetic inspiration with flow-physics-based design provides an effective, low-cost, and industrially applicable solution for noise mitigation in rotating machinery, offering a promising pathway toward the development of next-generation low-noise aerodynamic systems. https://jvs.isav.ir/article_741897.html The main factors producing noise by marine vessels are the propulsion system and its floating propeller. Accordingly, reducing the noise of marine propellers a fundamental role in reducing the noise emitted from marine systems. One of the methods of reducing the noise of marine propellers is the use of Contracted and Loaded Tip propellers (CLT), In this study, the design of a submerged marine propeller was optimized with the aim of reducing its noise level by making geometric changes to the winglet blades and converting it into a CLT propeller. In order to optimize the winglet blade section, four parameters of Plate contraction, flap angle, Plate elongation and Plate Cutting Angle were used. Based on the Taguchi method, 9 design modes were proposed out of 81 modes and their sound pressure levels at the first and second blade frequencies were extracted. In order to find the optimal levels for the noise produced, it was determined that the flap angle has the greatest effect on reducing the noise level. Finally, by determining the most optimal design mode, the designed CLT propeller found a noise reduction of 1.9% at the first blade frequency and 1.65% at the second blade transition frequency compared to the reference propeller. https://jvs.isav.ir/article_742392.html For accurate measurement of acoustic properties using an impedance tube, the generated acoustic wave must propagate within the waveguide as a plane wave. In impedance tube standards, the dimensions of the waveguide are selected such that plane-wave propagation is ensured. Owing to the absence of a standard for impedance tubes operating in water and the closer acoustic impedance matching between water and the waveguide walls compared with air, it is necessary to investigate plane-wave propagation in water-filled waveguides. In this study, wave propagation inside a water-filled impedance tube and the corresponding mode shapes are simulated using the finite element method. Two impedance tube configurations in air and three configurations in water are analyzed, and the maximum deviation from plane-wave behavior is reported for all modes. Furthermore, the modes in which the wave departs from plane-wave propagation are identified, and their mode shapes are presented. Finally, a waveguide with optimized dimensions and a broader operating frequency range than those reported in previous studies is proposed. In addition, plane-wave propagation in the proposed waveguide is examined under three conditions: rigid walls, dimensions suggested in the literature, and increased wall thickness.