Local Vibration Research Articles

A single exposure to prolonged flexor carpi radialis muscle vibration increases sensorimotor cortical areas activity.

Prolonged local vibration (LV) is thought to promote brain plasticity through repeated Ia afferents discharge. However, the underlying mechanisms remain unclear. This study therefore aimed at determining the acute after-effects of 30-min LV of the flexor carpi radialis muscle (FCR) on sensorimotor (S1, M1) and posterior parietal cortex (PPC) areas activity. Sixteen healthy participants were tested before and immediately after 30 min of FCR LV. Electroencephalographic signals were recorded during isometric submaximal wrist flexions. Time-frequency analyses were performed at source levels during contraction preparation, contraction initiation, force plateau and relaxation. After LV, the results showed an increase in alpha and beta desynchronizations in the source activity for the estimated M1, S1 and PPC during contraction preparation (p ≤ 0.05) and contraction initiation (p ≤ 0.05; except for PPC in the beta band: p = 0.07), as well as a greater alpha desynchronization in M1, S1 and PPC (p < .01) during force plateau. No LV-induced changes were observed during relaxation. Prolonged LV on the upper limb could increase estimated cortical activity within M1, S1 and PPC areas during subsequent isometric contractions. This could be due to LV-induced Ia afferents inputs projecting onto cortical areas through proprioceptive pathways, and likely triggering brain use-dependent plasticity.

Frequency-independent damping models for a high-rise building with simultaneous horizontal and vertical seismic motions

Recent seismic analyses indicate that the structural damping ratio should be considered frequency-independent, for safe and accurate estimations. In response, damping models like the Wilson–Penzien (WP) damping model, that is one of the modal damping, provide frequency independence across all modes; however, these models require considerable computational resources, especially for large-scale models. While Rayleigh damping is computationally efficient, it maintains a nearly constant damping ratio only within a limited frequency range. To address these limitations, several alternative damping models have been introduced, such as uniform (UN), causal hysteretic (CH), and extended Rayleigh (ER). We use the factor Wξ to represent the frequency range where the damping ratio remains approximately constant, defined as the ratio of maximum to minimum frequencies (fmax/fmin), within a specified tolerance of the target damping ratio. For Rayleigh damping, Wξ = 3.7, while the CH and ER models achieve Wξ values greater than 20. Although the UN model achieves a high Wξ, it demands large computational resources in the implicit analyses, commonly used for seismic response studies. In this study, we address the simultaneously inputting horizontal and vertical seismic motion into a large-scale dynamic analysis model of a high-rise building. In this analysis, horizontal, vertical, and local beam vibration modes spanning a wide frequency range appeared. Considering that these modes require the same damping ratio, damping models with Wξ values of 50 or higher are desirable. However, this threshold considerably exceeds Wξ values achievable with the existing models, rendering these models unsuitable for the intended application. Therefore, we propose and validate the efficiency of two new damping models (ER-W and CH19) that meet this requirement by improving existing models. Using these damping models, it is possible to analyze the horizontal and vertical modes and local vibration modes of the beam, assuming a simultaneous horizontal and vertical input to a high-rise building.

Long-Range Anion Correlations Mediating Dynamic Anharmonicity and Contributing to Glassy Thermal Conductivity in Well-Ordered K2Ag4Se3.

Herein an extremely low (0.32‒0.25 Wm-1K-1) and glassy temperature-dependence (300-600K) of lattice thermal conductivity (κlat)in a monoclinic K2Ag4Se3 is reported. It is found that the effective carrier delocalization, contributed by the perfect p-d* hybridization paradigm, can efficiently facilitate the spatial transfer of electron cloud perturbations induced by the anisotropic thermal vibrations of Ag4 atoms, thereby favoring long-range Se‒Se correlations. The localized rattling-like vibration of Ag4 atoms induce short phonon lifetimes, large scattering phase space, and then a low particle-like propagation. While the correlated interactions mediated competitive expressions between bubble diagrams and loop diagrams can suppress the generation of wavelike phonons from off-diagonal coupling. Ultimately, the AgSe3 structural units can enable the dual confinement of both the particle-like propagation of phonons and wavelike tunneling of coherence. The study highlights that the correlated AgSe3 coordination units can simultaneously target particle-like and wavelike phonons and then reduce their contribution to the κlat by mediating long-range transfer of charge polarization. These fundamental advances will advance the design of crystalline materials with tailored thermal properties.

Control of the Wetting Ability of a Material by Local Vibration on the Interfacial Layer

The possibility of controlling the wetting ability of a material synthesized in the interfacial layer of a heterogeneous liquid/liquid system by local vibration has been shown. The influence of the nature of the organic acid, metal and solvent on the contact angle of the interfacial layer material adhering to various substrates was studied. It has been established that with local vibration, a material with a more ordered structure, with higher roughness and lower water content, and, as a consequence, with a higher contact angle, is synthesized. On the studied substrates, hydrophobic coatings with contact angles of 100–163° were obtained, which retained their water-repellent properties under atmospheric conditions for a long time.

Localized Vibrations and Bound Exciton Mediated Emission in 2D Dion–Jacobson Perovskites

AbstractHerein, the emission characteristics of diammonium N,N,N′,N′‐tetramethyl‐1,4‐phenylenediammonium (TMPDA) are investigated based on lead iodide (TMPDA)PbI4 perovskite single crystals correlated with the localized lattice vibrations. Dual emission characteristics are ascribed to the existence of free exciton and bound exciton. The photoluminescence spectra as a function of excitation power and temperature show that structural distortion and exciton‐phonon coupling impact emission characteristics substantially. The coupling strength between excitons and phonons in (TMPDA)PbI4 is estimated as γac = 308.96 µeV and γLO = 62.3 meV, which is much higher than inorganic semiconductors. Further, bound exciton band recombination is significantly suppressed at lower temperatures due to increased localization of carriers. Specific heat deviation from the Dulong–Petit law indicates strong coupling in the lattice. The Debye‐Einstein model reveals multiple low‐energy localized independent vibrations, leading to phonon coupling with bound excitons. This interplay, along with Bosonic features, significantly influences emission properties. Further, it is observed that photocurrent as a function of the incident intensity follows a law ∝ I0α with α = 0.54, attributed to substantial bimolecular recombination of carriers. The findings of the study provide an in‐depth understanding of emission characteristics, lattice distortion, and interplay of electron‐phonon coupling in DJ phase 2D perovskite system.

Investigation on the characteristics of flow-induced vibration and noise of acoustic window with embedded compound acoustic black holes

In recent decades, acoustic black hole (ABH) structures have shown significant potential for suppressing structural vibrations and noise radiation. However, the ABH structure has not been applied to panel–cavity noise control under heavy fluid loading. In this study, a hybrid numerical approach was used to analyse the vibro-acoustic response suppression mechanism of a compound acoustic black hole (CABH) acoustic window under turbulent boundary layer (TBL) excitation. Both sides of the acoustic window interact with the water. The results show that the local vibration modes of the CABH lead to a strong interaction between the structure and damping material. The amplitude of the high-order modal wavenumber spectra of the CABH was small, which weakened the spatial coupling between the TBL pressure and the structure. The coupling strength between the CABH acoustic window and the internal sound field was reduced, causing noise suppression inside the cavity. To further examine the noise reduction performance of the CABH panel cavity system, a flow-induced experiment with a large-scale CABH acoustic window was carried out in a large cavitation channel, and the results showed significant hydrodynamic self-noise reduction.

Computer vision-based substructure isolation method for localized damage identification

In recent years, vision-based structural damage identification techniques have garnered significant attention due to their simplicity and cost-effectiveness. Nevertheless, dynamic response-based vision methods face challenges related to the limitations of the field of view (FOV), i.e., the extent of the FOV is often sacrificed in order to ensure sufficient monitoring accuracy, which reduces the amount of data available for structural health monitoring (SHM). This study presents a solution to this problem by employing the substructure isolation method (SIM), which focuses on local vibrations of the structure and enables local damage identification by isolating the area of interest. Additionally, a method combining kernelized correlation filter (KCF) with sub-pixel template matching is used to extract vibration information recorded by visual sensor. This strategy balances both the efficiency and accuracy of displacement extraction. In numerical simulations, the performance of the SIM based on acceleration response and displacement response is compared, demonstrating the potential compatibility of visual sensors with the SIM. Finally, the effectiveness of the proposed vision-based local damage identification method is validated through vibration testing of a shear frame model.

Vibration optimization methods of dredger engine room

Abstract Due to the large number and heavy weight of equipment, as well as the high center of gravity in the cabin area of dredgers, the concentrated arrangement of equipment is prone to local vibration problems in the cabin area. Additionally, there are many devices that need to be placed under the deck in the cabin area, which imposes significant constraints on the placement of supports. Using the finite element method to analyze the vibration problem of a certain dredger, we studied the influence of different equipment arrangements and structural reinforcement methods on vibration. This allowed us to summarize the characteristics of vibration under different improvement methods, providing feasible solutions for improving the vibration problem in the cabin area of dredgers. After adjusting the equipment layout and reinforcing local structures, the vibration in the dredger’s cabin area ultimately meets the design requirements satisfactorily.

Harmonic analysis of phase-sensitive optical time-domain reflectometer

This study innovatively proposes a method of using harmonics to mitigate the influence of fading noise in Phase-Sensitive Optical Time-Domain Reflectometer (Φ-OTDR). Numerical modeling was conducted to investigate the behavior of the Φ-OTDR. A section optical fiber is coiled around a PZT (piezoelectric transducer). By applying a signal to the PZT, it emulates an external vibration. The response of the simulated vibration was extracted using phase demodulation algorithm. In the response spectrum of the vibration, the fundamental frequency may be submerged because of the fading noise, causing the useful information to be obscured. However, the region impacted by fading noise in the fundamental frequency is unaffected in certain harmonic components. Thus, information from the harmonics can be used to compensate for the missing information in the fundamental frequency. By analyzing multiple harmonic components, the accuracy of vibration detection and localization can be improved. Experiment was performed to corroborate the findings, and the results demonstrated good consistency with the simulated data. Both the simulation and the experiment proved that considering harmonics can enhance the measurement accuracy of Φ-OTDR. This discovery provides new insights and methods for the application of Φ-OTDR.

Atomic-scale visualization of defect-induced localized vibrations in GaN.

Phonon engineering is crucial for thermal management in GaN-based power devices, where phonon-defect interactions limit performance. However, detecting nanoscale phonon transport constrained by III-nitride defects is challenging due to limited spatial resolution. Here, we used advanced scanning transmission electron microscopy and electron energy loss spectroscopy to examine vibrational modes in a prismatic stacking fault in GaN. By comparing experimental results with ab initio calculations, we identified three types of defect-derived modes: localized defect modes, a confined bulk mode, and a fully extended mode. Additionally, the PSF exhibits a smaller phonon energy gap and lower acoustic sound speeds than defect-free GaN, suggesting reduced thermal conductivity. Our study elucidates the vibrational behavior of a GaN defect via advanced characterization methods and highlights properties that may affect thermal behavior.

Comparative assessment of neurotrophic proteins in vibration disease

Introduction. The problem of health impairment due to the impact of physical factors, including vibration disease (VD), retains medical and social relevance due to the significant specific gravity in the structure of occupational morbidity and high prevalence. Under vibration exposure, the acid-base equilibrium, immune status are disturbed, rheological properties and properties of the neurohumoral system, as well as functional indices of the central and peripheral nervous system change. Neurotrophins are known to play an important role in regulating the development and functioning of the central and peripheral nervous systems. In this regard, research is needed to determine in VD patients the levels of neurospecific proteins, which may serve as one of the markers for tracing changes in the nervous system in workers. The aim of the study was to identify the peculiarities of changes in neurospecific proteins (BDNF, S100β, and MBP) in the serum of patients with VD of different genesis. Materials and methods. Serum concentrations of neurotrophic proteins: brain neurotrophic factor – BDNF, S100β protein and myelin basic protein (MBP) were studied by solid-phase enzyme-linked immunoassay. Results. There was an increase in serum BDNF, S100β protein, and MBP concentrations in persons with VD due to combined exposure to local and general vibration, and an increase in MBP was observed in patients with VD due to exposure to local vibration. Limitations. The limitations of this work are small groups of employees. Conclusion. As a result of studies, it can be assumed that in VD due to exposure to combined vibration, changes are observed in the peripheral and central parts of the nervous system, and in VD due to local vibration, disorders seem to be mainly associated with the peripheral nervous system. The general pattern of the revealed disorders in the content of MBP lies in the neurodestructive processes occurring in the nerve fibers in patients with VD, regardless of genesis. Summarizing the above mentioned, the validity of studying the concentration of neurospecific proteins in vibration disease occurring with damaging processes in the nervous tissue should be recognized.

The effect of three different nonpharmacological methods on cannulation success during peripheral intravenous catheter placement in the emergency unit: a randomized controlled trial

BackgroundPeripheral 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.MethodsA 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.ResultsIt 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.ConclusionsIt 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 registrationClinicalTrials.gov ID NCT06378424, retrospectively registered 20/04/2024.

A Study on the Mast Structure Vibration Limits considering the Operating Time of Naval Ships

The mast structure of a naval ship has a lot of expensive equipment attached and is easily exposed to strong vibration due to its structural characteristics, so it is necessary to manage vibrations well to prevent equipment failure and increase operating time. Since September 2015, the Navy has been managing the vibration of the ship's mast structure with a separate tolerance standard from the local vibration, but this standard is set at 1/2 of the vibration limits for mast-mounted equipment without any engineering basis. So the establishment of new vibration limits based on the operating conditions of naval ships is required. In this study, the mast structure vibration limits were reviewed considering the actual operating time of naval ships, and the results were compared with the standards of major overseas classification societies and the actual measurements of a ship that had mast structure vibration problems.

Acute effects of local vibration inducing tonic vibration reflex or illusion of movement on maximal wrist force production.

Local vibration (LV) mainly stimulates primary afferents (Ia) and can induce a tonic vibration reflex (TVR) and an illusion of movement. This study aimed to evaluate the effect of these two phenomena on maximal voluntary isometric contraction (MVIC) capacity. LV (80 Hz) was applied to the wrist flexor muscles in two randomized experiments for 6 min. LV conditions were adjusted to promote either TVR (visual focus on the vibrated wrist) or ILLUSION [hand hidden, visual focus on electromyographic activity of the flexor carpi radialis muscle (FCR)]. Mechanical and electromyographic (EMG) responses of the FCR and extensor carpi radialis muscles were recorded during MVIC in flexion and extension and during electrically evoked contractions at supramaximal intensity. Measurements were performed before (10 min and just before) and after (0 and 30 min) LV protocol. An increase in FCR EMG was observed during LV in the TVR condition (+340%) compared with the illusion condition (P = 0.003). In contrast, the movement illusion was greater in the ILLUSION condition (assessed through subjective scales) (P = 0.004). MVIC was reduced in flexion only after the TVR condition ([Formula: see text], all P < 0.034). Moreover, the decrease in force was correlated with the amount of TVR recorded on the FCR muscle (r = -0.64, P = 0.005). Although potentiated doublets of each muscle did not evolve differently between conditions, a decrease was observed between the first and the last measure. In conclusion, when conducting research to assess maximal strength, it is necessary to have better control and reporting of the phenomena induced during LV.NEW & NOTEWORTHY The maximal force production of the vibrated muscle is reduced after 6 min of LV only in TVR condition. Furthermore, the amount of TVR is negatively correlated with this force decrease. When measuring the effects of LV on maximal force production, it is important to control and report any phenomena induced during vibration, such as TVR or movement illusion, which can be achieved by recording EMG activity of vibrated muscle and quantifying illusion.

Control over the Wettability of a Material by Local Vibration on the Interfacial Layer

Control over the Wettability of a Material by Local Vibration on the Interfacial Layer

Simultaneous low-frequency vibration isolation and energy harvesting via attachable metamaterials

In this study, we achieved energy localization and amplification of flexural vibrations by utilizing the defect mode of plate-attachable locally resonant metamaterials, thereby realizing compact and low-frequency vibration energy suppression and energy harvesting with enhanced output performance. We designed a cantilever-based metamaterial unit cell to induce local resonance inside a periodic supercell structure and form a bandgap within the targeted low-frequency range of 300–450 Hz. Subsequently, a defect area was created by removing some unit cells to break the periodicity inside the metamaterial, which led to the isolation and localization of the vibration energy. This localized vibration energy was simultaneously converted into electrical energy by a piezoelectric energy harvester coupled with a metamaterial inside the defect area. Consequently, a substantially enhanced energy harvesting output power was achieved at 360 Hz, which was 43-times higher than that of a bare plate without metamaterials. The proposed local resonant metamaterial offers a useful and multifunctional platform with the capability of vibration energy isolation and harvesting, while exhibiting easy handling via attachable designs that can be tailored in the low-frequency regime.

Optimization analysis of vibration reduction for aeroengine multistage blade-disk system

In order to reduce the vibration localization of multistage blade-disk system of aeroengine compressor, the integral model and substructure model of multistage blade-disk system are established by using substructure modal synthesis method, and the dynamic characteristics of two models are analyzed and the accuracy of the substructure model is verified by comparison. Based on the substructure model, two optimization algorithms of the random wear mass and the snake optimization are proposed. The results show that the vibration amplitudes of the two models are in good agreement in the first 200 modes, and the substructure model meets the requirement of analysis accuracy. Both optimization algorithms can effectively reduce the degree of the vibration localization of the mistuned blade-disk system. The random wear mass algorithm can quickly reduce the amplitude of the blade. The snake optimization algorithm can find the global optimal solution with enough iterations. The results show that the maximum vibration amplitude and the vibration localization factor after optimization are reduced by 5.72 % and 12.0 % respectively by using the random wear mass algorithm, and that of 9.13 % and 16.7 % respectively by using the snake optimization algorithm. The analysis method presented in this paper takes into account the analysis efficiency and analysis precision, it can be used for dynamic analysis and vibration reduction optimization of large power machinery such as aeroengine and gas turbine, and provides a basis for further improving the reliability and service life of aircraft.

Hygienic assessment of the protective properties of personal hand protection equipment during vibration testing

Introduction. In industrial environments, at the workplaces of hand tool operators, it is not always possible to completely eliminate increased levels of vibration exposure. The power and speed characteristics of modern hand-held machines are constantly increasing. The impact of local vibration on a person has a negative effect on his body. When working with hand tools, personal protective equipment is used. The purpose of personal hand protection against vibration is to reduce the vibration impact on a person. Materials and methods. Bench tests were carried out on hand protection products consisting of damping materials of various shapes and locations in the product. The vibration sensor was installed and fastened in places where the operator’s hands came into contact with vibration and on the forearm. The effectiveness of protection was determined by the difference in measurement levels. Results. During the tests, vibration levels were recorded on the handle of the vibration stand, the palmar surface, the fingers, and the operator’s forearm. In the low-frequency region of the spectrum, vibration attenuation is minimal, and as the frequency range increases, the attenuation increases. Across all areas of the spectrum, performance levels for mittens are higher than for gloves. In places where the fingers come into contact with vibration, the efficiency is less than when in contact with the hand, and in the low-frequency region of the spectrum a negative efficiency of up to 0.8 dB is noted. Vibration measurements on the operator’s forearm showed vibration levels in the forearm to be lower than in the hand. Limitations. The study was conducted over a period of one year, in laboratory conditions, and was limited to two thousand measurements. Conclusion. Hygienic assessment of the effectiveness of the protective properties of personal protective equipment for hands was carried out in accordance with developed laboratory test methods when installing and securing a vibration sensor on the handle, hand, and forearm of the operator. Determining the effectiveness of the entire product model should be considered when designing and manufacturing new hand protection against vibration.

Assessment of the long-term trend in angiodystonic syndrome of the upper extremities in stage I vibration disease using the ultrasound method

Introduction. Diseases of the upper extremities caused by exposure to local vibration at the workplace are a ubiquitous problem. These diseases occur or are aggravated by exposure to vibration at the workplace when using vibration-hazardous equipment. Purpose of the study – is to identify the features of upper limb angiodystonic syndrome in vibration disease at stage I, depending on work experience. Materials and methods. Ultrasound scanning of the arteries of the upper extremities was performed in seventy patients. Spectral and velocity indices such as resistance index (RI), diastolic blood flow rate (V ED), systolic (pulse) blood flow rate (V PS) and pulsation index (PI) were measured in the distal part of the forearm. Results. Upon contact with a vibration tool, for each year of work experience, the systolic (pulse) blood flow rate (V PS) in the radial and left ulnar arteries significantly were found to decrease by an average of 0.57–0.58 (p&lt;0.05). In the ulnar artery, PI increases on average by 0.03–0.062, but the changes are not statistically significant (p&gt;0.05). With an increase in the length of service by 1 year, the RI in the left radial and ulnar arteries significantly increases by 0.0003–0.0012 (p&lt;0.05). Limitations of the study. The main disadvantages of ultrasound are the long-term and operator-dependent method. Conclusion. With an increase in work experience, the indices characterizing angiodistonic disorders: pulsation index (PI), resistance index (RI) – significantly increase with each year of experience when exposed to local vibration. This can be used for differential diagnosis of peripheral angiodistonic upper limb syndrome of occupational etiology, in particular, vibration disease associated with exposure to local vibration at stage 1. With an increase in work experience, the indices characterizing angiodistonic disorders: pulsation index (PI), resistance index (RI) – significantly elevate with each year of experience when exposed to local vibration. As part of the ultrasound screening study, scanning of the arteries of the upper extremities in patients at the clinic of occupational pathology can be performed at the preclinical stage to prevent prolonged chronic ischemia of the upper extremities. This diagnostic method can be especially valuable in differentiating peripheral angiodistonic upper limb syndrome of occupational etiology, in particular, vibration disease at the stage 1.

A Proof-of-Concept Study of Stability Monitoring of Implant Structure by Deep Learning of Local Vibrational Characteristics

This study develops a structural stability monitoring method for an implant structure (i.e., a single-tooth dental implant) through deep learning of local vibrational modes. Firstly, the local vibrations of the implant structure are identified from the conductance spectrum, achieved by driving the structure using a piezoelectric transducer within a pre-defined high-frequency band. Secondly, deep learning models based on a convolutional neural network (CNN) are designed to process the obtained conductance data of local vibrational modes. Thirdly, the CNN models are trained to autonomously extract optimal vibration features for structural stability assessment of the implant structure. We employ a validated predictive 3D numerical modeling approach to demonstrate the feasibility of the proposed approach. The proposed method achieved promising results for predicting material loss surrounding the implant, with the best CNN model demonstrating training and testing errors of 3.7% and 4.0%, respectively. The implementation of deep learning allows optimal feature extraction in a lower frequency band, facilitating the use of low-cost active sensing devices. This research introduces a novel approach for assessing the implant’s stability, offering promise for developing future radiation-free stability assessment tools.