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Context: Soft tissue mobilization is frequently employed for delayed onset muscle soreness (DOMS) management. Foam roller and percussive massage are 2 popular soft tissue mobilization methods preferred by various professionals. However, their effects on DOMS symptoms are controversial and there are no studies comparing these 2 methods. The aim of the present study was to compare the acute effects of soft tissue mobilization with a foam roller or a percussive massage device on DOMS in young male recreational athletes. Design: A parallel, single-blinded, randomized controlled trial. Methods: Thirty-six participants (median [interquartile range 25/75]; age: 20.0 [19.3/21.0] y) were randomly allocated to percussive massage group (n = 12), foam roller group (n = 12), and control group (n = 12). First, a fatigue protocol targeting quadriceps femoris was performed. Then, participants received soft tissue mobilization with foam roller/percussive massage or rested for 10 minutes according to their groups. Pain and fatigue were evaluated by a visual analog scale, and the skin surface temperature of over the quadriceps femoris was measured with thermal camera imaging. Evaluations were performed at baseline, following fatigue protocol, at 24th hour, and at 48th hour. Changes from the baseline at 24th and 48th hours were compared between groups. Results: No significant between-group differences were observed at the assessments performed at 24th or 48th hour regarding the changes from baseline in pain (P value for 24th hour = .905, P value for 48th hour = .733), fatigue (P value for 24th hour = .895, P value for 48th hour = .606), or skin surface temperature measurements (P values for 24th hour = between .300 and .925, P values for 48th hour = between .311 and .750). Conclusions: Soft tissue mobilizations applied with foam roller or percussive massage device do not seem to be superior to passive resting in alleviating DOMS symptoms in recreational athletes. [ABSTRACT FROM AUTHOR]

One of the main limitations to increasing productivity in machining processes is the emergence of self-excited vibrations. In the turning of titanium alloys, due to its mechanical properties, the material presents low machinability and is prone to the appearance of chatter during processing. Therefore, for this purpose, the material is machined using moderate machining parameters, aiming for parts with a better surface finish and avoiding the appearance of chatter. Therefore, this work seeks to evaluate the influence of machining parameters, cutting speed, feed rate, and cutting depth on vibration during the process and on the roughness of the parts. For this, experiments were carried out varying these parameters, and then the influence of each of them was analyzed using the Taguchi method for planning experiments and signal-to-noise for analyzing the variability of the collected data. It was found that the cutting depth and feed have an influence on the vibration during, where the greater the parameter, the greater the RMS of the signal. And the roughness of the parts is influenced by the cutting speed, in which the higher the speed, the lower the roughness of the parts. [ABSTRACT FROM AUTHOR]

This paper presents a procedure for the application of a multifractal spectrum to analyse vibration signals obtained during static bending tests of selected fibre reinforced polymer matrix composite materials. The analyses were designed to determine the failure course of the composites tested under bending conditions. Non-stationary changes occurring in the signals include low- and high-energy symptoms of progressive damage in materials, which are difficult to identify and interpret, especially in the early stages. Determined using fractal leaders, the multifractal spectra of the vibration signals calculated for the different stages of the bending test allowed qualitative identification of the changes caused by progressive damage with different energy responses. In addition, the quantitative measures of change in the characteristics of the multifractal spectrum determined clearly indicated the changes occurring in the recorded signals. It can be concluded from the research that the proposed signal processing method based on a multifractal spectrum determined from non-stationary vibration signals is sensitive to changes occurring in these signals. [ABSTRACT FROM AUTHOR]

AbstractThe insulation and noise and vibration damping characteristics of complex systems used by humans, such as automobiles, airplanes and ships are becoming increasingly important from the early design stages to ensure an adequate level of comfort. Especially in the naval fields, the design of insulation plans is crucial to prevent the propagation of noise and vibrations on board of megayachts. Since it is quite complex to identify and correctly model the sources due to their deterministic and random nature, during the early design stage, the focus is on insulation rather than reducing the acoustic levels of the sources themselves. In this article, a method for analyzing sea trials on a superyacht will be proposed with the aim of analyzing how much the insulation materials can limit the levels of vibrational energy on board during the path between sources and receivers. A new a descriptor based on harmonic transmission energy through the structure is proposed for path insertion loss experimental identification. In particular, by using spectral analyses and synchronous averaging of sound levels in various areas of the superyacht, it will be possible to study the vibroacoustic insulation of structural materials and their damping coefficient. [ABSTRACT FROM AUTHOR]

AbstractAmong the diverse adhesive-bonded joining methods, the co-curing technique offers several advantages for fusing structural components. Co-curing technique effectively enhances specific strengths and ensures more equitable stress distribution. This research investigated the multi-walled carbon nanotubes (MWCNTs) incorporated with varying wt.% in carbon fibre-reinforced polymeric (CFRP) composite joints through co-cure bonding techniques. The effects of flexural and vibration behaviour in CFRP composite joints were evaluated using the three-point bending and free vibration tests. Experimental results revealed that the epoxy adhesive containing 0.5 wt.% nanofiller demonstrated the highest flexural strength and modulus. These values were significantly superior to pure epoxy adhesive, exhibiting increases of 270 and 120%, respectively. However, the 1.0 wt.% of nanofiller exhibited the maximum natural frequency under three vibration modes, which is 29, 17, and 14% higher than the pure epoxy adhesive. The statistical analysis of the results was examined using an ANOVA, ensuring the reliability of the findings. Optimisation and prediction were done with the Levenberg-Marquardt artificial neural network, further reinforcing the confidence in the outcomes. The overall coefficient (R) mean square error of 0.99844 is within the acceptable range, indicating that both outcomes are reliable and in agreement. [ABSTRACT FROM AUTHOR]

Introduction: This study evaluated the effects of localized vibration (LV) in 37 dogs with bilateral hip dysplasia (HD). HD is a common cause of lameness in dogs, and is a contributory factor to osteoarthritis, which can reduce the dog's overall quality of life. Materials and methods: This was a multi-center, prospective survey-based study of 37 dogs with bilateral HD and no prior history of surgical management. Dogs were given LV therapy daily for 14 consecutive days using the same commercially available handheld vibration device. Canine Brief Pain Index (CBPI) data was collected prior to the initiation of therapy, then for 14 days following daily LV therapy. The dogs' medications, supplements, additional rehabilitation modalities, and activity level were unchanged during the study period. Baseline CBPI pain severity and pain interference scores were compared to scores after 7 or 14 days of LV. Results: There were significant decreases in average pain severity and average pain interference CBPI scores in response to 7 and 14 days of therapy compared to baseline. When response to therapy was defined as a decrease in both pain severity score and pain interference score, 62% (23/37) of dogs responded to therapy at 7 days of treatment and 73% (27/37) responded at 14 days of treatment. Of the individuals that responded to treatment at 7 days, 91% (21/23) continued to respond at 14 days. Conclusion: Daily LV resulted in a significant reduction in CBPI scores in 73% of dogs with bilateral HD in this study. Randomized and blinded studies should be performed to further assess daily LV as a treatment modality for canine HD. [ABSTRACT FROM AUTHOR]

Dynamic testing of systems is most realistic of real-world conditions when multiple input and multiple output (MIMO) techniques are used. To replicate measured environmental conditions, a series of desired outputs (responses) on the system must be realized by inverting the frequency response functions (FRF) matrix for input estimation. System identification is dependent on the number of inputs and outputs, which affect the type of solutions. In input estimation, the auto spectra of the determined inputs are affected by both the auto spectra and cross spectra of the desired outputs. This research evaluates errors and investigates two sources in an experimental setting. The first significant error source is test-to-test variability in FRFs from system identification tests, quantified by magnitude variability from long-duration tests. The second significant error source is the realization of time histories from frequency domain inputs. The spectral content of the realized random process deviates from the desired content and is also quantified. The structure is a linear three-story frame fixed at the base; two inputs are provided uniaxially with the use of suspended electrodynamic shakers. The proposed model for error sources was found to be effective in predicting errors in a SISO (single-input single-output) and a square (2-input 2-output) MIMO test. [ABSTRACT FROM AUTHOR]

In this paper, attention was focused on identifying the components of the amplitude-frequency spectrum of pressure pulsations in a hydraulic system in which an external low-frequency mechanical vibration was subjected to a proportional hydraulic directional control valve. It was observed that an operating machine or device equipped with hydraulic valves is a source of mechanical vibrations with a wide frequency spectrum. The influence of these vibrations on the pressure pulsation spectrum was analyzed, identifying the components resulting from the forcing of the directional control valve spool. In addition, it was noted that the pressure pulsation spectrum includes components resulting from the pulsation of the displacement pump output feeding the hydraulic system. A description of these spectrum components was also made and, using the solution superposition method, the components of the pressure pulsation spectrum over a wide frequency range were identified. [ABSTRACT FROM AUTHOR]

Lahore is among the most important historical cities in Pakistan, and many cultural heritage structures, such as Shalamar Gardens and Lahore Fort, which are recognised as World Heritage Sites by UNESCO, are located there. The rapid increase in transit operations and infrastructure development in Lahore can increase the vulnerability of nearby heritage structures to ground-borne vibrations. In this study, a vibration vulnerability assessment of the heritage structures present in Lahore was performed with the help of the framework provided by the Federal Transit Administration (FTA), USA. A remote survey was carried out to gather valuable information regarding the distance between the heritage structures and potential vibrational sources, as well as the latitude and longitude of the heritage structures, via the web-based mapping tool Google Earth. A vibration vulnerability map of heritage structures was developed on the basis of a vibration vulnerability assessment to make it convenient for policymakers to visualise the present state of heritage structures with respect to vibration vulnerability. The performed vibration vulnerability assessment was validated by experimentally measuring vibrations at the Buddha's Tomb (Buddha Ka Awa) heritage structure. The study revealed that 17% of the heritage structures present in Lahore are vulnerable to vibrations at present, with potential vibrational sources such as road traffic, metro trains, and rail traffic. The vibration vulnerability assessment revealed that 72% of the vibrationally vulnerable heritage structures in Lahore are most influenced by vibrations from road traffic. The results of this study can aid policymakers in creating intervention packages for vibrationally vulnerable heritage structures in Lahore in relation to their respective needs, which will make it possible to achieve the sustainable conservation of heritage structures. [ABSTRACT FROM AUTHOR]

Flexoelectricity indicates a unique characteristic of insulators and dielectric materials that results in electrical polarization induction in response to the non-uniform strain gradient. The impact of this property is bolder on the microscale and nanoscale rather than the macroscale. This article is conducted to derive the governing equations of motion for a flexoelectric-multilayer structure and evaluate its vibrational behavior in response to various variable variations. The model includes a functionally graded (FG) porous core which is confined between two flexoelectricity-based face sheets at both sides and a Vlasov type of foundation. To gain the governing equations, the new type of power law for porous material beside Hamilton's principle (HP) and modified couple stress theory (MCST) is implemented. Capturing the effects of length scale parameter, different materials, aspect and thickness ratios, porosity index, foundation parameter and boundary conditions (B.C.s) on the normalized natural frequency (NNF) of such a multilayer model based on the novel FG porous material formulation serve as the main novelty of this article. According to the results, it is revealed that the lateral ratio enhancement causes NNF and stiffness reduction in the model. Furthermore, among all considered B.C.s, simply support (SSSS) and clamped support (CCCC) refer to the lowest and the highest NNF respectively. The content of the recent article serves as a good source to provide a better understanding of the vibrational response of high stiffness-to-weight ratio structures to different variable variations. [ABSTRACT FROM AUTHOR]

This paper dealt with the vibration characteristics of an auxetic rectangular plate under in-plane compression. Firstly, the equivalent bending stiffness matrix of a star-shaped auxetic plate was obtained using Castigliano's theorem and the homogenization technique. Then, employing the classical plate theory (CPT) in conjunction with the Rayleigh–Ritz method, the natural frequencies of auxetic plate were extracted. The chebyshev polynomial series has been selected to define the assumed displacement fields of the plate. Convergence study for the Rayleigh–Ritz method was conducted. The accuracy of the proposed mathematical model for the star-shaped auxetic plate was validated using the results from a finite element analysis (FEA). Effects of unit cell geometric parameters on the natural frequencies of the plate were examined. The auxeticity angle of star-shaped pattern had a significant effect on the natural frequencies. The present approach can be extended into other auxetic patterns, such as re-entrant bowtie auxetics. [ABSTRACT FROM AUTHOR]

Aim: This initial Norwegian study aimed to quantify the vibrations and sounds experienced by neonates when they were transported by helicopter in an incubator. Methods: Two neonatal manikins weighing 500 and 2000 g were placed in a transport incubator and transported in an Airbus H145 D3 helicopter during standard flight profiles. The vibrations were measured on the mattress inside the incubator and the sound levels were measured inside and outside the incubator. Results: The highest vibration levels were recorded during standard flight profiles when the lighter manikin was used. These ranged 0.27–0.94 m/s2, compared to 0.27–0.76 m/s2 for the heavier manikin. The measurements exceeded the action levels set by the European Union Vibration Directive for adult work environments. The sound levels inside the incubator ranged 84.6–86.3 A‐weighted decibels, with a C‐weighted peak level of 122 decibels. The sound levels inside the incubator were approximately 10 decibels lower than outside, but amplification was observed in the incubator at frequencies below 160 Hz. Conclusion: Vibrations were highest for the lighter manikin. The sound levels during helicopter transport were higher than recommended for neonatal environments and sounds were amplified within the incubator at lower frequencies. [ABSTRACT FROM AUTHOR]

Small hydro technology is playing a crucial role in advancing sustainable, clean energy policies as part of the global hydro development strategy. Its contribution to social and economic development is becoming more prominent, particularly in ensuring electricity access for rural communities and supporting industrial expansion. The main causes of bulb turbine failures under high operating conditions are frequently attributed to variations in pressure in the draft tubes, which are aggravated when a spinning vortex rope is formed under load operation. Different fluid injection techniques, namely compressed air and water jet injection, address these issues and reduce the negative results of cavitation. The investigation covers the flow visualization on the suction side of a single hydrofoil utilizing a cavitation tunnel and a bulb turbine. This study assesses the effectiveness of compressed air injection in reducing vibration generated by cavitation in bulb turbines. Positive results of the experimental studies suggest a decrease in noise and vibration by air injection that prevents oscillations of the vortex rope. This research also considers how the hydrofoil design of bulb runner blades influences flow characteristics. Hence, it provides knowledge on cavitation structures in diverse cavitation numbers. Different studies that compare the original and modified hydrofoil designs reveal remarkable improvements that may be due to changes in the key parameters of the hydrofoil, such as later cavitation initiation and reduced intensity. To obtain the optimal output of a bulb turbine by considering air injection for vibration reduction and hydrofoil design changes to limit the negative effect of cavitation, the Reynolds number and cavitation number are to be defined. This multidisciplinary approach possesses enormous potential to increase the reliability and efficiency of bulb turbines in challenging operating conditions. [ABSTRACT FROM AUTHOR]

The article combines the finite element method with the novel-type sinusoidal hyperbolic shear strain hypothesis to study the static bending response and dynamics of nanoplates subjected to simultaneous mechanical, thermal, and voltage loads. The plate equilibrium equation is developed from the concept of potential work, which takes into account the impact of the flexoelectricity effect. The formula for the electric field that is operating on the plate becomes more complicated when the new strain theory is used; nonetheless, its complexity adequately displays both the mechanical and electrical components, as well as the electromechanical components, that are acting on the nanoplate. The computational theory is also verified through comparison with previously published data. The article also investigates the influence of some material factors, temperature, and external voltage on displacement response and charge polarization of nanoplates in the case of subjecting to static and time-varying loads. The results demonstrate that the thermomechanical-electrical response of nanoplates is dependent on numerous factors, which serve as the foundation for the practical design and application of nanostructures. [ABSTRACT FROM AUTHOR]

This investigation presents a comparative accuracy and parametric study for analyzing the vibration characteristics of a bi-direction functionally graded (BDFG) beams. In this respect, two numerical techniques, harmonic differential quadrature (HDQ) and generalized differential quadrature (GDQ) method, are used to calculate the natural frequencies of the BDFG beam. Here, the material parameters are supposed to be varied continuously in the longitudinal and the thickness directions under an exponential rule. Hamilton's approach is employed to derive the equations of motion and corresponding end conditions. Four boundary conditions are taken in this study. The equations of motion are discretized using HDQ and GDQ techniques. The results obtained using HDQ and GDQ methods are compared with those obtained using the different numerical methods in the literature. Comparative analysis of the behavior of bi-Directional functionally graded beams using GDQ and HDQ is not available in the literature. The results show that HDQ and GDQ methods have good consistency. Moreover, the effects of exponent parameters, geometric parameters and boundary conditions on the natural frequency of BDFG beams are also examined. [ABSTRACT FROM AUTHOR]

In this study, computational modelling of an exponential functionally graded material (EFGM) beam is proposed to demonstrate the vibration characteristics of exponential functionally graded material (EFGM) beams subjected to general end conditions. The mechanical parameters of the beam vary exponentially in a longitudinal direction. The width of the beam varies by an exponential expression in the longitudinal direction. The four end conditions are employed in this analysis, i.e., clamped–clamped, clamped-simply supported (CS), simply supported-simply supported and clamped-free (CF). The finite element software based on the finite element method is used to calculate the eigenfrequencies. The effect of exponent parameters, thickness-to-length ratio and end condition is analyzed. It can be stated from the results that natural frequency decreases when the exponent parameters lie in the range from − 1 to 0. While it increases when the exponent parameters lie from 0 to 1 under the fixed end condition. The natural frequencies decrease for CS and CF end conditions when the exponent parameters lie from − 1 to 1. In a simply supported end condition, the natural frequency increases when the exponent parameters lie from − 1 to 0. While it decreases when the exponent parameters lie from 0 to 1 for the first mode. The natural frequency decreases for the second mode when the exponent parameters lie from − 1 to 0. While it increases when the exponent parameters lie from 0 to 1. [ABSTRACT FROM AUTHOR]

Microneedle transdermal administration and low-frequency ultrasound represent two important physical penetration-promoting methods for enhancing drug penetration. This article aims to investigate and compare the effects of drug penetration enhancement through transdermal administration using vibrating microneedles versus low-frequency sonophoresis. In Vitro permeation studies were conducted using Valia-Chien double chamber diffusion cells to evaluate the transdermal delivery of tetramethylpyrazine hydrochloride (TMPH). The TMPH concentration in the receiving compartment was determined using high-performance liquid chromatography (HPLC). Several combinations of microneedles and ultrasound settings were investigated, including different needle heights, vibration frequencies, exposure times, and assorted distances of ultrasound horn and skin. The results revealed the vibrating microneedle system as the most efficacious treatment to increase the TMPH permeability into the rat skin. The combination of a larger needle, higher frequency, and a 3-min exposure led to a 41.92-fold increase in cumulative permeability compared to the control group. The ultrasound treatment exhibited a moderate enhancement effect on TMPH skin penetration. Using a horn-to-skin distance of 3 mm and a 3-min exposure resulted in a 4.34-fold increase in TMPH cumulative permeation compared to the control group. It could be concluded that while both the vibrating microneedle and the low-frequency ultrasound systems act as penetration enhancers for promoting the TMPH permeation through the skin, the vibrating microneedle system notably demonstrates a more effective penetration-promoting effect. System illustrations and permeation effects between vibrating microneedle and low-frequency sonophoresis systems. [ABSTRACT FROM AUTHOR]

AbstractIn this research, the free vibration and supersonic flutter analyses of a cylindrical sandwich shell with a reinforced honeycomb core (RHC) integrated with piezoelectric face sheets are investigated. The core is a honeycomb structure enriched with fibers and carbon nanotubes (CNTs). The layers of the shell are modeled based on the Cooper-Naghdi shell theory and the continuity conditions between the layers are considered. The aerodynamic pressure of the supersonic flow is modeled using the linear piston theory. Hamilton’s principle is used to derive the governing equations. A semi-analytical solution is presented including an exact solution in the circumferential direction followed by a numerical solution in the longitudinal direction via the differential quadrature method (DQM). The effects of several parameters on the frequencies, the corresponding damping coefficients, and the critical aerodynamic pressure are investigated. It is concluded that improving the stiffness of the honeycomb core with the CNTs does not necessarily improve the aeroelastic stability of the shell. The presented results can be used in the design and analysis of aerospace structures. [ABSTRACT FROM AUTHOR]

BACKGROUND: Vibration environment can cause spinal injury, especially in patients with scoliosis. At present, there is no information about the inherent mode of the whole spine from T1 to the pelvis in scoliosis patients in the free state. OBJECTIVE: To analyze the dynamic characteristics of the whole spine in patients with scoliosis by the finite element method. METHODS: Based on CT scan images, a three-dimensional finite element model of the T1-pelvic total spine of an 11-year-old patient with thoracolumbar biflexion scoliosis was established, and the Cobb angles of thoracolumbar scoliosis were 36° and 24°, respectively. The mode analysis in the free state of the whole spine was carried out by the finite element method. RESULTS AND CONCLUSION: The fifteen-order free modes of the spine were extracted, and the dynamic characteristics of the scolio-curved spine were obtained. The resonance frequency distribution of the spine was concentrated. The thoracic vertebra was the most deformed in the whole spine model, and the amplitude of the thoracic vertebra was larger than that of the lumbar vertebra. Modal analysis was used to analyze the vibration characteristics of scoliosis patients in the vibration environment. It is of great significance to determine the natural frequency, vibration mode, and amplitude of scoliosis patients for analyzing the vibration characteristics of scoliosis. [ABSTRACT FROM AUTHOR]

The increasing deployment of wind turbines in technologically advanced nations underscores the need to enhance their reliability, extend their operational lifespan, and minimize failures. The current protection devices for wind turbine components do not sufficiently shield them from various external factors that degrade performance. This study addresses the environmental and technical challenges that disrupt wind turbine operations and reviews existing research and technical solutions for protecting individual components, supported by experimental findings. Using a decomposition method followed by the integration of protection components, we propose a combined protection system designed to improve the overall resilience of wind turbines. The proposed system aims to reduce incidents, extend service life, and increase reliability, addressing a critical gap in wind energy technology and contributing to its continued development and efficiency. [ABSTRACT FROM AUTHOR]

Paper presents an effective technique for developing reduced-order models to predict the dynamic responses of systems using the receptance coupling and frequency-based substructuring (RCFBS) method. The proposed approach is particularly suited for reconfigurable dynamic systems across various applications, like cars, robots, mechanical machineries, and aerospace structures. The methodology focuses on determining the overall system receptance matrix by coupling the receptance matrices (FRFs) of individual subsystems in a disassembled configuration. Two case studies, one with distributed parameters and the other with lumped parameters, are used to illustrate the application of this approach. The first case involves coupling three substructures with flexible components under fixed–fixed boundary conditions, while the second case examines the coupling of subsystems characterized by multiple masses, springs, and dampers, with various internal and connection degrees of freedom. The accuracy of the proposed method is validated against a numerical finite element analysis (FEA), direct methods, and a modal analysis. The results demonstrate the reliability of RCFBS in predicting dynamic responses for reconfigurable systems, offering an efficient framework for reduced-order modeling by focusing on critical points of interest without the need to account for detailed modeling with numerous degrees of freedom. [ABSTRACT FROM AUTHOR]

Background: Peripheral intravenous catheterization is frequently performed in emergency units, but it is a procedure which is difficult for healthcare professionals and painful for patients. The primary objective of the present study was to examine the effect on venous dilation, procedure duration and pain severity of local heat, cold and vibration applications performed on the intervention area before peripheral intravenous catheterization in adults. The second objective of the study was to examine the effects of age and gender variables on the participants' pain intensity levels. Methods: A single-blinded randomized controlled trial. The study included 120 adults who were randomly selected between March and August 2023. One application group (n = 30) received local heat application, one group (n = 30) received local cold application, and one (n = 30) received local vibration using the Buzzy® device. The applications, to the site of the peripheral intravenous catheterization, lasted one minute. The control group (n = 30) received standard peripheral intravenous catheterization application. The groups' vein dilation was assessed with the vein assessment scale, pain felt during catheterization with the visual analog scale, and the duration of the procedure with a chronometer. Results: It was found that the venous dilation of the cold application group was significantly higher (p = 0.010, p = 0.015 respectively) and procedure duration was shorter (p = 0.013, p < 0.001 respectively) than that of the heat and vibration application groups, and its pain severity was significantly lower (p = 0.002, p = 0.001 and p = 0.001 respectively) than that of the control group and the heat and vibration application groups. Conclusions: It was determined that local cold application for one minute to the area of peripheral intravenous catheterization increased venous dilation, shortened application time, and reduced pain. Trial registration: ClinicalTrials.gov ID NCT06378424, retrospectively registered 20/04/2024. [ABSTRACT FROM AUTHOR]

Changes in the surrounding environment, if transmitted to the electron microscope, are frequently perceived as noise that diminishes the quality of the images. However, in fact, ‘noises’ contain rich information about the environment. This work reports a very rare event where aberration‐corrected HAADF‐STEM images were acquired during the impact of seismic waves, resulted from a mild earthquake. By analysing these images, we found that the drift and vibration of the sample are detectable and quantifiable. Despite many potential challenges, this work demonstrates the utilisation of electron microscopes in detecting and monitoring seismic waves with high spatial resolution, which may lead to unique applications in the low‐frequency regime. [ABSTRACT FROM AUTHOR]

Finger joints are one of the most important and widely used joints in the wood and wood products industry. The design, type of construction, and the type of glue used, etc., are the most important things in this joint that determine its final quality. In this research, the effect of cellulose nanofiber and nanoclay in polyvinyl acetate (PVA) glue at levels of 0, 0.4, and 1.5% in finger joints with lengths of two fingers of 5 and 10 mm was investigated by the free vibration in free-free beam method. In joints without nanoparticles, finger joints with a finger length of 10 mm had better acoustic properties than joints with a finger length of 5 mm, except for the acoustic conversion efficiency factor. The results showed that by adding cellulose nanofiber (CNF) and nanoclay in both finger lengths of 5 and 10 mm at both 0.4% and 1.5% levels, the dynamic modulus of elasticity, elastic stiffness, acoustic coefficient, and acoustic conversion efficiency increased significantly, while the damping factor values showed a significant decrease. In general, the effect of CNF on the acoustic properties of both types of joints was better than that of nanoclay. [ABSTRACT FROM AUTHOR]

Diamond/aluminum composites have the advantages of high thermal conductivity and low density, making them ideal cooling materials for aerospace electronic devices. However, there is a lack of comprehensive research on the factors influencing the thermal conductivity of diamond/aluminum composites, as well as their reliability. In view of the above problems, spark plasma sintering method was utilized to prepare diamond/aluminum composites with a thermal conductivity of 462 W/(m·K). It considered the effects of sintering temperature, holding time, and diamond particle size combination. Additionally, the heat spreader reliability of this diamond/aluminum composite in high and low temperature and vibration environment was studied. The results demonstrated that the diamond/aluminum composite effectively reduced the heat source temperature by 13 °C compared to aluminum alloy when subjected to a heat flux of 70 W/cm². Furthermore, diamond/aluminum composites can maintain stable physical properties and structural reliability in the high and low temperature and vibration environment, effectively exerting their heat dissipation capacity. Overall, diamond/aluminum composites can be presented as a reliable solution for heat dissipation in aerospace electronic devices. [ABSTRACT FROM AUTHOR]

Impact-driven pipe piles are commonly used in offshore structures, but vibratory driving is becoming more popular due to advantages regarding noise emissions, material fatigue and installation time. In offshore practice, crane-guided vibratory driving is used for maximum control over the installation process. Regarding the load-bearing behaviour of piles, the influence of the installation method is currently subject to research. To contribute to this question, comparative scale model investigations were carried out on impact-driven, jacked and vibratory-driven piles in dense sand. The tests focused on variations of vibratory installation parameters, including crane-guided and free vibratory driving. Based on measurements at the pile and in the soil, the influence of dynamic pile motions on the soil stress development could be analysed. The well-known increase of radial effective soil stresses due to impact driving could be reproduced. The tests showed that the same effects could be evoked by free vibratory driving if certain vibration parameters were met. Increased soil stresses may be beneficial for the lateral or axial pile behaviour, but can cause problems regarding drivability. A sequential application of crane-guided and free vibratory driving may optimise both the installation process and the bearing behaviour. [ABSTRACT FROM AUTHOR]

The tapered pile is usually divided into finite segments along the vertical direction due to its variable cross-section when investigating its torsional dynamic characteristics. However, an annular projection would be formed at the contact surface of the adjacent pile segments due to the difference in radius, through which the surrounding soil will apply the circumferential support on the pile segment. In this study, the Voigt model is adopted to model the circumferential support of the surrounding soil acting on the annular projection. On this basis, an amended impedance function transfer method is established combined with the circumferential stress equilibrium equations and circumferential displacement continuity conditions at the contact surface of the adjacent pile segments. The shear complex stiffness transfer method is employed to consider the construction disturbance during pile installation. Then, an improved analytical solution for the torsional vibration of the tapered pile considering the circumferential support of the surrounding soil is established by solving the equations for the soil and pile. Based on the solution, the torsional vibration of the tapered pile is investigated and the influence of the circumferential support of the surrounding soil is revealed under different pile parameters and construction disturbance conditions. [ABSTRACT FROM AUTHOR]

A mechanism to explain pile shaft resistance during vibratory driving is discussed. One hypothesis is that horizontally oscillating stresses temporarily reduce shaft resistance. Vibration measurements were conducted in medium-dense to dense sand during vibratory driving. A large compaction probe was installed by a vibrator with variable frequency. The driving process and ground response were documented in detail. Geophones were installed on and below the ground surface. Horizontal ground vibrations were measured at three levels below the ground surface. The difference in vibration response of the ground during driving at a high frequency (27 Hz) and at the system resonance frequency (15 Hz) showed the effect of the vibrator operating frequency on penetration speed and emitted ground vibrations. Horizontal stress pulses are emitted along the probe shaft, which can temporarily reduce static horizontal stresses acting against it. This phenomenon can explain the temporary reduction of shaft resistance and efficiency of vibratory driving in granular soils. As a result of these pulses, the horizontal stresses are increased permanently. Using a monitoring and process control system, the system resonance frequency can be determined in the field – a critical parameter for vibratory driving resistance, emission of ground vibrations and vibratory compaction of granular soils. [ABSTRACT FROM AUTHOR]

This study focuses on the influence of the pile end soil on the torsional vibration of a pile based on a fictitious soil pile model considering stress diffusion. The pile end soil is simulated as a cone-shaped fictitious soil pile whose parameters remain the same as the soil. The dynamic equilibrium equations for the pile–soil system subjected to torsional dynamic loadings are developed and solved to obtain the corresponding analytical solution. Then, comparisons with other solutions are conducted to verify the reliability of the proposed solution. Finally, parametric analysis results are presented based on the proposed solution to portray the influence of the stress diffusion angle, thickness and shear wave velocity of the pile end soil. [ABSTRACT FROM AUTHOR]

This study proposes a piecewise high-order differential interpolation method with rapid convergence to construct an ultrasmooth high-speed cam profile. The proposed method enables a solution to be realized to manipulate the dynamic performance of a cam profile with C3 continuity during the whole working process. The reconstruction characteristics of the cam profile by the high-order differential interpolation method are compared with the most commonly used linear profile interpolation strategy. Thus, the proposed piecewise high-order differential interpolation method is validated as a feasible and effective methodology to design and reconstruct an ultrasmooth cam profile. [ABSTRACT FROM AUTHOR]

The present study analyzes the vibrations of a curved laminated beam with magnetostrictive layers and patches for vibration suppression. Hamilton's Principle is used to establish the equations of motion. An analytical solution examines a beam with simply-supported boundaries (H-H), while the finite element method (FEM) considers various boundary conditions (H-H, C-C, and C-F). The analytical solutions incorporate magnetostrictive layers as active controllers, while the FE formulation includes smart patches for wider application. The study also investigates the in-plane stress of a laminate composite layer. Finally, a parametric study demonstrates the accuracy and practicality of the derived formulations. [ABSTRACT FROM AUTHOR]

The reliability of electric vehicles (EVs) is crucial for the performance and safety of modern transportation systems. Electric motors are the driving force in EVs, and their maintenance is critical for efficient EV performance. The conventional fault detection methods for motors often struggle with accurately capturing complex spatiotemporal vibration patterns. This paper proposes a recurrent convolutional neural network (RCNN) for effective defect detection in motors, taking advantage of the advances in deep learning techniques. The proposed approach applies long short-term memory (LSTM) layers to capture the temporal dynamics essential for fault detection and convolutional neural network layers to mine local features from the segmented vibration data. This hybrid method helps the model to learn complicated representations and correlations within the data, leading to improved fault detection. Model development and testing are conducted using a sizable dataset that includes various kinds of motor defects under differing operational scenarios. The results demonstrate that, in terms of fault detection accuracy, the proposed RCNN-based strategy performs better than the traditional fault detection techniques. The performance of the model is assessed under varying vibration data noise levels to further guarantee its effectiveness in practical applications. [ABSTRACT FROM AUTHOR]

The work is devoted to the consideration of methods for determining the strain of objects using fiber Bragg gratings under a high-frequency vibration or pulsed mechanical action, which is difficult to perform using widespread methods and devices. The methods are based on numerical processing of the time dependence of the radiation power reflected from the fiber Bragg grating at various wavelengths, which makes it possible to measure strain parameters in a wide range of magnitude and frequencies. The efficiency of the proposed methods is demonstrated by numerical simulation. It is shown that it is possible to restore the strain dependence on time in the range ± 1000   μ ϵ or more from simultaneously measured power dependencies reflected by the fiber Bragg grating using common fiber-optic components. The case of sequential registration of reflected radiation power at different wavelengths to determine the probability density of the distribution of the strain values is also considered. The results of signal processing obtained both by numerical simulation and experimentally for the case of a linear vibration are presented. The technical problems of using the proposed methods are discussed. [ABSTRACT FROM AUTHOR]

This investigation reveals the reasons behind severe shear distortion of carbon fiber towpreg observed during a series of winding sequences involving a geometry consisting of a hyperbolic hyperboloid attached to two cylinders at its open sides. The roving severely distorts at the transition zones, tending to slip and lose track, while the robust winding machine undergoes noticeable and unexpected vibrations. The DO IT 2 root cause analysis problem-solving method is applied to understand the failure mechanism using flow and causal diagrams, along with CNC data analysis. The winding angle at geometric transitions is measured using photographs. Additional data analysis involves evaluating the limits of mathematical functions used to construct the mandrel meridian profile, along with analyzing winder kinematics. The results reported here reveal numerical singularities that adversely affect solutions at all levels by impacting the mathematical definition of the meridian profile. This explains the shear-type distortion of the towpreg, speed changes surpassing ISO 10816-1 standards on mechanical vibration, alongside peaks in acceleration and jerk. Moreover, it is suggested that Coulomb's friction law may surpass its limits due to a viscous and tacky interface promoted by the non-rigid nature of the stranded towpreg. Preventive actions involve meeting the requirements of the Theory of Curves and Surfaces for mandrel meridian profile construction. Additionally, incorporating observed viscoelastic and shear strength phenomena into theoretical approaches is advised, alongside addressing discrepancies in measuring the filament winding angle and validating numerical solutions against CNC data. [ABSTRACT FROM AUTHOR]

Background: Pain is a common non-motor symptom in patients with cervical dystonia (CD), severely impacting their quality of life. The pathophysiology of CD is incompletely understood but it involves altered processing of proprioceptive and pain signals. Objectives: The purpose of this proof-of-concept study was to determine if vibro-tactile stimulation (VTS)—a non-invasive form of neuromodulation targeting the somatosensory system—can modulate neck pain in people with CD. Methods: In a multi-center study, 44 CD patients received VTS to sternocleidomastoid and/or trapezius muscles for up to 45 min under 9 different stimulation conditions that either targeted a single or a pair of muscles. The primary outcome measure was a perceived pain score (PPS) rated by participants on a 100-point analogue scale. Results: During VTS, 29/44 (66%) of participants experienced a reduction in PPS of at least 10% with 17/44 (39%) reporting a reduction in pain of 50% or higher. After VTS cessation, 57% of participants still reported a 10% or higher reduction in PPS. Effects were significant at the group level and persisted for up to 20 min post-treatment. No distinct optimal stimulation profiles were identified for specific CD phenotypes. Clinical markers of disease severity or duration did not predict the degree of VTS-induced pain reduction. Conclusion: This proof-of-concept study demonstrates the potential of VTS as a new non-invasive therapeutic option for treating neck pain associated with CD. Further research needs to delineate optimal dosage and long-term effects. [ABSTRACT FROM AUTHOR]

In this paper, size-dependent static bending and also free and forced vibration analyses of composite microplates are studied based on the modified couple stress theory (MCST) and quasi-3D sinusoidal shear deformation theory. The composite microplate is composed of epoxy reinforced with functionally graded graphene nanoplatelets (GPLs). The governing equations are derived utilizing Hamilton's principle and are solved for simply supported microplate using Navier's approach. The accuracy of the presented solution is confirmed and the effects of various parameters on the static and dynamic deflections and natural frequencies of the microplate are investigated including material length scale parameter and surface area, thickness, mass fraction, and distribution pattern of the GPLs. Numerical results confirm that subjoining the GPLs to the polymer reduces the static and dynamic deflections of the microplates and increases the natural frequencies. It is concluded that to achieve the highest reduction in the static and dynamic deflections and the highest growth in the natural frequencies, it is more helpful to use the GPLs with the larger surface areas and put them as far as away from the neutral surface of the microplate. [ABSTRACT FROM AUTHOR]

This paper reexamines the linear and nonlinear free vibration responses of porous sandwich cylindrical shells with graphene platelet (GPL) reinforcements surrounded by an elastic medium under temperature conditions. The graphene platelets reinforced composite (GPLRC) core is assumed to be multilayers, and each layer may have different values of porosity coefficient to achieve a piece-wise functionally graded pattern. By introducing an inhomogeneous model instead of the equivalent isotropic model (EIM), the Young's moduli along with the shear modulus of porous GPLRC core are predicted through a generic Halpin–Tsai model in which the porosity is included. Thermo-mechanical properties of porous GPLRC core and metal face sheets are assumed to be temperature dependent. Motion equations of porous sandwich cylindrical shells reinforced by GPLs are formulated based on the Reddy's third order shear deformation theory. In the modeling, von Kármán nonlinear strain-displacement relationships, shell-foundation interaction and thermal effect are also taken into account. The analytical solution for the nonlinear vibration problem is obtained by applying a two-step perturbation approach. Numerical studies are performed to compare the results obtained from the present model and the EIM. The results reveal that, in most cases, the difference of the fundamental frequency between the two models is over 10% and in that case the EIM is not suitable for the linear free vibration analysis of porous sandwich cylindrical shells reinforced by GPLs, whereas for the nonlinear-to-linear frequency ratio curves, the difference between the two models is less than 2% when the non-dimensional vibration amplitude reaches 1.0 and in that case the EIM may be valid in the analysis for the same shell. [ABSTRACT FROM AUTHOR]

• A theoretical model for the dynamic and vibro-acoustic of three novel honeycomb sandwich panels is established. • The vibration and acoustic properties of three novel honeycomb sandwich panels are analyzed. • An improved constrained YDSE is proposed by introducing penalty functions, circle chaotic mapping, and levy flight. • Optimization of the vibrational and acoustic performance of three novel honeycomb sandwich panels is conducted. Utilizing the first-order shear deformation theory (FSDT) and Hamilton's principle, dynamic equations for tunable Poisson's ratio metamaterial honeycomb sandwich panels have been derived. These panels include petal-shaped, star-shaped, and butterfly-shaped designs. The acoustic response of these panels when subjected to plane harmonic sound waves has been formulated, treating them as fluid-structure interaction systems. To enhance the structural vibration and sound propagation attributes, traditional metallic aluminum has been replaced with graphene platelet-reinforced composites (GPLRC). Through computational analysis and finite element simulation data, the natural frequencies and sound transmission loss (STL) characteristics of the panels have been determined. An improved heuristic algorithm called the circle chaos mapping and levy flight enhanced Young's double-slit experiment optimizer (CLYDSE) has been introduced to optimize their vibrational and acoustic properties. This algorithm builds upon Young's double-slit experiment optimizer (YDSE) by incorporating circle chaos mapping for initializing a monochromatic light source and utilizing the levy flight principle for more accurate search results. These enhancements allow the CLYDSE algorithm to avoid local optima and improve convergence velocity. A penalty function method was employed to establish mass and equivalent elastic modulus as optimization constraints, aiming to achieve superior specific stiffness. Finally, structural optimization using the proposed CLYDSE method was conducted to enhance the vibrational and acoustic performance of the three types of honeycomb sandwich panels. The results validate the effectiveness of the theoretical model in predicting vibration and acoustic response, as well as the improved performance of the CLYDSE algorithm in terms of convergence velocity and optimization accuracy. This demonstrates the algorithm's efficacy in refining the acoustic and vibrational qualities of these advanced honeycomb structures. [ABSTRACT FROM AUTHOR]

Exploration rovers have difficulty moving underground because the drag force from the ground restricts their movement; this hinders underground exploration. This study aimed to address this challenge. We posit a hypothesis that the rover can move underground by imparting vibration to the ground and changing the drag force. To validate this hypothesis, a testbed that moves underground was developed, and the drag force when imparting vibration was investigated. The results revealed that the drag force while imparting vibration is smaller than that after imparting vibration, and we accordingly devised the operation for moving underground. The proposed operation causes bias of the drag force by imparting vibration to make the testbed move in the direction of the small drag force. The effectiveness of the proposed method was assessed through an experiment wherein the testbed was set to move underground. The experimental results demonstrate the superiority of the proposed method, as the movement distance achieved with vibration is considerably greater than that without vibration. The findings validate the hypothesis that using vibration for underground motion is effective in improving mobility and provides valuable insights into the design of robots for underground motion. [ABSTRACT FROM AUTHOR]

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bearing is the property of Bearing Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study evaluates the dynamic performance of a reference footbridge under human–structure interaction (HSI) effects using real-time hybrid simulation (RTHS). The footbridge, designed with precise multi-axial dynamic sensitivity, is tested under pedestrian gait velocities of 1.20, 1.50, and 1.80 m · s − 1 . The RTHS framework involves an analytical continuous model of the footbridge as a numerical substructure and real human gait loads as the experimental substructure. The results reveal significant dynamic coupling between pedestrian-induced loads and the responses of the structure. Lateral vibrations exhibit a fundamental frequency of approximately 1.0 Hz, whereas vertical vibrations peaked near 2.0 Hz. Dynamic synchronization, particularly at higher gait velocities, amplified the structural vibrations, with lateral loading increasing by up to 300% in the middle span. Vertical loads show substantial amplification and attenuation depending on gait velocity and footbridge location. Lateral accelerations display a dispersion of approximately 15.0%, whereas vertical accelerations showed higher variability, with dispersions reaching up to 20%. The RTHS technique demonstrates high fidelity and accuracy, with global errors below 2.95% and delays of less than 2.10 ms across all evaluated directions. These results emphasize the critical importance of accounting for HSI effects in the design of pedestrian footbridges because human-induced vibrations can significantly impact structural serviceability and user comfort. This study offers important insights into optimizing footbridge design to mitigate the risks of excessive vibrations and ensure both safety and functionality under typical pedestrian loads. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shanghai Jiaotong University (Science) is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The utilization of functionally graded graphene platelet-reinforced composites (FG-GPLRC) and honeycomb sandwich constructions is prevalent in the field of engineering. Therefore, it is crucial to investigate the buckling and vibration properties of these materials under heat circumstances. This paper specifically focuses on the vibration and thermal buckling characteristics of a novel multi-arc concave honeycomb sandwich plate (MACHSP) equipped with an adjustable positive-negative Poisson's ratio. The governing equations of motion for the system are derived based on the first-order shear deformation theory in conjunction with Hamilton's principle. The formulation of the system's characteristic equation involves the establishment of displacement functions that satisfy distinct boundary conditions. Using computational programming, natural frequencies, mode shapes, and critical buckling temperatures of MACHSP with three different FG-GPLRC distributions under thermal influences are determined. Subsequently, these results are compared with outcomes from finite element simulations and findings from previously published literature. Additionally, the amplitude-frequency response characteristics of the structure under harmonic excitation are analyzed, followed by a discussion of the impact of structural parameters on its buckling and vibration characteristics. The results indicate that the established theoretical model for predicting the buckling and vibration characteristics of MACHSP with FG-GPLRC distribution aligns well with simulation models and prior research. In contrast to solid plates, MACHSP not only achieves a substantial reduction in weight but also demonstrates a significant increase in natural frequency. Furthermore, graphene platelets have the potential to enhance the structure's natural frequency values and critical buckling temperatures. Lastly, various structural parameters exert a notable influence on the structure's performance. [ABSTRACT FROM AUTHOR]

Regarding the monitoring and control technology of pumped storage power stations, the monitoring methods for the operating parameters of the turbines in pumped storage power stations were first analyzed, including the monitoring locations and methods for pressure and vibration, as well as the analysis of the reasons for special operating conditions; Secondly, the operation monitoring and fault diagnosis system of pumped storage power stations was summarized and introduced, including the commonly used monitoring systems, fault diagnosis principles, and application situations. Finally, the development trend of turbine monitoring technology and fault diagnosis was discussed. [ABSTRACT FROM AUTHOR]