Найдено 46
Digital-Twin of the National Collegiate Athletic Association Specified Energy Rebound Testing Device: Kinetic-Energy Absorption by a Basketball Rim and Backboard Modeled with ANSYS Workbench Finite Element Analysis
Winarski D., Nygren K.P., Winarski T.
Q2
MDPI
Vibration, 2025, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
This paper is the first to offer a digital-twin of the Energy Rebound Testing Device, which is specified by the National Collegiate Athletic Association for the sport of basketball. This digital-twin replicates the physical ERTD, which was previously studied empirically. This paper merges the original finite element analysis of a basketball rim and backboard with the finite element analysis of the Energy Rebound Testing Device, using the ANSYS Workbench 2024R2, student edition. The first modal model was of the ERTD in isolation in the Workbench Modal Analysis system, and the natural frequency modeled via finite element analysis, 12.776 Hz, compared favorably with the empirical modal analysis value of 12.72 Hz. The second modal model, also in the Workbench Modal Analysis system, was of the ERTD rotatably attached to a basketball rim and backboard. This second model was then imported into the Transient Structural Analysis system and first used to confirm the hypothesis that the ERTD did indeed transfer kinetic energy from its drop-mass to the basketball rim and backboard. Then, an energy transfer surface was used to confirm the hypothesis that this kinetic energy transfer was responsive to changes in rim and backboard stiffness via changes in the respective Young’s moduli. Finally, a second-generation ERTD was proposed, where the control box transmits its energy readings to “the cloud” via the WiFi capabilities of the Arduino UNO R4 WiFi.
Parameter Estimation of Nonlinear Structural Systems Using Bayesian Filtering Methods
Erazo K.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
This paper examines the performance of Bayesian filtering system identification in the context of nonlinear structural and mechanical systems. The objective is to assess the accuracy and limitations of the four most well-established filtering-based parameter estimation methods: the extended Kalman filter, the unscented Kalman filter, the ensemble Kalman filter, and the particle filter. The four methods are applied to estimate the parameters and the response of benchmark dynamical systems used in structural mechanics, including a Duffing oscillator, a hysteretic Bouc–Wen oscillator, and a hysteretic Bouc–Wen chain system. Based on the performance, accuracy, and computational efficiency of the methods under different operating conditions, it is concluded that the unscented Kalman filter is the most effective filtering system identification method for the systems considered, with the other filters showing large estimation errors or divergence, high computational cost, and/or curse of dimensionality as the dimension of the system and the number of uncertain parameters increased.
Analysis of Displacement Transmissibility and Bifurcation Behavior in Nonlinear Systems with Friction and Nonlinear Spring
Hur D.J., Hong S.C.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
In this paper, a nonlinear vibration system with friction and linear and nonlinear springs is modeled and analyzed. The analysis examined how the combination of nonlinear variables affects the displacement of the system using the slowly varying amplitude and phase (SVAP) method. The break-loose frequency at which relative motion begins was obtained as a function of the friction ratio, and it was found that the displacement transmissibility differed depending on the change in design parameters. The displacement transmissibility response showed a unique phenomenon in which bifurcation occurred in the front resonant branch before the maximum response point when the linear damping coefficient was small and the friction coefficient was large, and the displacement transfer curve was separated at a specific parameter value. This phenomenon can be divided into three parameter zones considering the bifurcation pattern and stability of the displacement transmissibility curve. In addition, a 3-D spatial zone of dimensionless parameters was presented, which can predict stability during the design process, along with the drawing method and procedure. This can be conveniently utilized in the process of setting the parameters of the isolators considering the stability of the response during the design. In the analysis and design process of vibration isolators with friction damping, this study has important implications for practical applications.
Modular Modeling of a Half-Vehicle System Using Generalized Receptance Coupling and Frequency-Based Substructuring (GRCFBS)
Hamedi B., Taheri S.
Q2
MDPI
Vibration, 2024, цитирований: 3,
open access Open access ,
PDF, doi.org, Abstract
This paper presents an advanced modular modeling approach for vertical vibration analysis of dynamic systems using the Generalized Receptance Coupling and Frequency-Based Substructuring (GRCFBS) method. The focus is on a four-DoF half-vehicle model comprising three key subsystems: front suspension, rear suspension, and the vehicle’s trimmed body. The proposed technique is designed to predict dynamic responses in reconfigurable systems across various applications, including automotive, robotics, mechanical machinery, and aerospace structures. By coupling the receptance matrices (FRFs) of individual vehicle modules, the overall system receptance matrix is efficiently derived in a disassembled configuration. Two generalized coupling methods, originally developed by Jetmundsen and D.D. Klerk, are employed to determine the complete vehicle’s receptance matrix from its subsystems. Validation is achieved by comparing the results with established methods, such as direct solution and modal analysis, demonstrating high accuracy and reliability for complex dynamic systems. This modular approach allows for the creation of reduced-order models focused on key measurement points without the need for detailed system representation. The method offers significant advantages in early-stage vehicle development, providing critical insights into system vibration behavior.
Rat-Tail Models for Studying Hand-Arm Vibration Syndrome: A Comparison between Living and Cadaver Rat Tails
Warren C.M., Xu X.S., Jackson M., McKinney W.G., Wu J.Z., Welcome D.E., Waugh S., Chapman P., Sinsel E.W., Service S., Krajnak K., Dong R.G.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
Over-exposure of the hand-arm system to intense vibration and force over time may cause degeneration of the vascular, neurological, and musculoskeletal systems in the fingers. A novel animal model using rat tails has been developed to understand the health effects on human fingers exposed to vibration and force when operating powered hand tools or workpieces. The biodynamic responses, such as vibration stress, strain, and power absorption density, of the rat tails can be used to help evaluate the health effects related to vibration and force and to establish a dose-effect relationship. While the biodynamic responses of cadaver rat tails have been investigated, the objective of the current study was to determine whether the biodynamic responses of living rat tails are different from those of cadaver rat tails, and whether the biodynamic responses of both living and cadaver tails change with exposure duration. To make direct comparisons, the responses of both cadaver and living rat tails were examined on four different testing stations. The transfer function of each tail under a given contact force (2 N) was measured at each frequency in the one-third octave bands from 20 to 1000 Hz, and used to calculate the mechanical system parameters of the tails. The transfer functions were also measured at different exposure durations to determine the time dependency of the response. Differences were observed in the vibration biodynamic responses between living and cadaver tails, but the general trends were similar. The biodynamic responses of both cadaver and living rat tails varied with exposure duration.
The Reduced-Order Modeling Approach for a Double-Damper Concept: A Comparison with a Single Damper for Comfort Analysis
Hamedi B., Shrikanthan S., Taheri S.
Q2
MDPI
Vibration, 2024, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
This paper explores the modeling and simulation of an innovative double-damper suspension system, evaluating its effectiveness through different test scenarios. The double damper integrates two individual dampers into a unified assembly. The modeling process involves representing the damper as two distinct dampers and a body block, accounting for the additional degree of freedom introduced by combining the two dampers. Simulink/MATLAB is employed for modeling the pressure, discharge, and force equations of the damper. A simplified quarter-car model is designed to conduct simulations for different road profiles, evaluating the efficacy of this double-damper model. The reduced-order modeling approach, suitable for complex systems like dampers, is utilized. Dedicated mathematical models are utilized to examine both single- and double-damper configurations, with the resulting non-linear equations solved using Newton’s iterative method. The equations derived for the single damper provide the basis for modeling the double-damper system. In this model, two separate dampers, each possessing similar properties, are simulated and considered to be rigidly linked at their connection point. Consequently, it is assumed that a portion of the force and velocity experienced by the lower damper is transmitted to the upper damper, and vice versa. Simulation results demonstrate that the innovative double-damper design outperforms a single passive damper in attenuating the oscillations of both the sprung and unsprung masses. Moreover, this innovative concept offers increased adaptability to balance between ride comfort and road holding, a feature previously limited to passive suspension systems.
Stability and Bandgap Characteristics of Periodic Marine Risers
Nikfarjam M., Baz A.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
This paper presents the concept of periodic marine risers, which is investigated in a comprehensive theoretical manner to establish tools for the design and prediction of the performance characteristics of this class of risers. The presented concept of periodic risers introduces an optimally placed and designed array of periodic inserts that reinforce the conventional riser to, on the one hand, enhance its elastic instability threshold to internal flows and, on the other hand, introduce stop/pass band characteristics that can trap the vortex shedding excitations in order to mitigate their effects. Such a concept has not been investigated in the literature. The effectiveness of the concept is investigated and demonstrated theoretically by modeling the dynamics of these risers using finite element analysis and developing their instability threshold to internal flows, as well as their bandgap characteristics by extracting the eigenvalues of the associated transfer matrices. Comparisons are established between the performance characteristics of these periodic risers and conventional risers to demonstrate the merits and limitations of the proposed concept.
Finite Element Analysis versus Empirical Modal Analysis of a Basketball Rim and Backboard
Winarski D., Nygren K.P., Winarski T.
Q2
MDPI
Vibration, 2024, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
The first goal of this research was to document the process of using the MODAL analysis system of the ANSYS 2024R1 student edition to create a finite element model of the modes and frequencies of vibration of one basketball rim and backboard design. This finite element model included the use of steel for the rim and its mount, a tempered glass backboard, and an aluminum frame behind the backboard. After a mesh was created, fixed support boundary conditions were applied to the four corners of the aluminum frame, followed by the theoretical modal analysis. The second goal was to validate this model by comparing the finite element calculated mode shapes and frequencies to the empirical modal analysis previously measured at the United States Military Academy at West Point, New York. Five mode shapes and frequencies agreed rather well between the theoretical finite element analysis and previously published empirical modal analysis, specifically where the rim was vibrating in the vertical direction, which was the direction that the accelerometer was aligned for the empirical modal analysis. These five modes were addressed from a finite element model validation standpoint by a 99.5% confidence in a 98.09% cross-correlation with empirical modal analysis data, and from a verification standpoint by employing a refined-mesh. However, three theoretical mode shapes missed by the empirical modal analysis were found where the vibration of the rim was confined to the horizontal plane, which was orthogonal to the orientation of our accelerometer.
Stick–Slip Suppression in Drill String Systems Using a Novel Adaptive Sliding Mode Control Approach
Zribi F., Sidhom L., Gharib M.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
A novel control technique is presented in this paper, which is based on a first-order adaptive sliding mode that ensures convergence in a finite time without any prior information on the upper limits of the parametric uncertainties and/or external disturbances. Based on an exponent reaching law, this controller uses two dynamically adaptive control gains. Once the sliding mode is reached, the dynamic gains decrease in order to loosen the system’s constraints, which guarantees minimal control effort. The proof of convergence was demonstrated according to Lyapunov’s criterion. The proposed algorithm was applied to a drill string system to evaluate its performance because such systems present variable operating conditions caused by, for example, the type of rock. The effectiveness of the proposed controller was evaluated by conducting a comparative study that involved comparing it against a commonly used sliding mode controller, as well as other recent adaptive sliding mode control techniques. The different mathematical performance measures included energy consumption. The proposed algorithm had the best performance measures with the lowest energy consumption and it was able to significantly improve the functioning of the drill string system. The results indicated that the proposed controller had 20% less chattering than the classic SM controller. Finally, the proposed controller was the most robust to uncertainties in system parameters and external disturbances, thus demonstrating the auto-adjustable features of the controller.
Analytical Study of Nonlinear Flexural Vibration of a Beam with Geometric, Material and Combined Nonlinearities
Madhuranthakam Y., Chakrapani S.K.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
This article explores the nonlinear vibration of beams with different types of nonlinearities. The beam vibration was modeled using Hamilton’s principle, and the equation of motion was solved using method of multiple time scales. Three models were developed assuming (a) geometric nonlinearity, (b) material nonlinearity and (c) combined geometric and material nonlinearity. The material nonlinearity also included both third and fourth nonlinear elasticity terms. The frequency response equation of these models were further evaluated quantitatively and qualitatively. The models capture the hardening effect, i.e., increase in resonant frequency as a function of forcing amplitude for geometric nonlinearity, and the softening effect, i.e., decrease in resonant frequency for material nonlinearity. The model is applied on the first three bending modes of the cantilever beam. The effect of the fourth-order material nonlinearity was smaller compared to the third-order term in the first mode, whereas it is significantly larger in second and third mode. The combined nonlinearity models shows a discontinuous frequency shift, which was resolved by utilizing a set of transition assumptions. This results in a smooth transition between the material and geometric zones in amplitude. These parametric models allow us to fine tune the nonlinear response of the system by changing the physical properties such as geometry, linear and nonlinear elastic properties.
Effects of In-Wheel Suspension on Whole-Body Vibration and Comfort in Manual Wheelchair Users
Neti A., Brunswick A., Marsalko L., Shearer C., Koontz A.
Q2
MDPI
Vibration, 2024, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
Frequent and prolonged exposure to high levels of vibration and shock can cause neck and back pain and discomfort for many wheelchair users. Current methods to attenuate the vibration have shown to be ineffective and, in some cases, detrimental to health. Novel in-wheel suspension systems claim to offer a solution by replacing traditional spokes of the rear wheels with dampening elements or springs. The objective of this study was to investigate the effects of in-wheel suspension on reducing vibration and shock and improving comfort in manual wheelchair users. Twenty-four manual wheelchair users were propelled over nine different surfaces using a standard spoked wheel, a Spinergy CLX, and Loopwheels while accelerometry data was collected at the footrest, seat, and backrest. Loopwheels lowered vibrations by 10% at the backrest compared to the standard and CLX wheels (p-value < 0.001) and by 7% at the footrest compared to the CLX (p-value < 0.05). They also reduced shocks by 7% at the backrest compared to the standard wheel and CLX (p-value < 0.001). No significant differences were found in comfort between the wheels. Results indicate that Loopwheels is effective at reducing vibration and shock, but more long-term testing is required to determine effects on health.
Assessing Ride Motion Discomfort Measurement Formulas
Klauder Jr L.T.
Q2
MDPI
Vibration, 2024, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
This article is about a framework for determining the degree of realism of any given passenger ride motion discomfort measurement formula. After providing some context and reviewing evidence of deficiency in currently popular ride motion discomfort measurement formulas, the article outlines the research program that needs to be carried out in order to establish such a framework. The research begins with gathering recordings of uncomfortable ride motion episodes encountered in a chosen type of passenger transport service. It then has test subjects compare the episodes via a ride motion simulator and adjust their amplitudes pair wise until they cause equal discomfort. It explains how to take the pair wise amplitude adjustments and determine amplitude adjustments that bring all of the motion episode recordings to a common level of discomfort so that they form a normalized set. Then, the lower the scatter of the scores assigned by any given discomfort measurement formula to the members of that set, the more realistic that formula will be for the chosen service.
Antihistamine Medication Blunts Localized-Vibration-Induced Increases in Popliteal Blood Flow
Needs D., Blotter J., Fellingham G.W., Cruse G., Gifford J.R., Johnson A.W., Feland J.B.
Q2
MDPI
Vibration, 2024, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
Localized vibration (LV) of the lower leg increases arterial blood flow (BF). However, it is unclear how LV causes this increase. Understanding the mechanisms of this response could lead to the optimized future use of LV as a therapy. One possible mechanism of LV-mediated BF is through histamine release by mechanosensitive mast cells. The purpose of this study was to measure the BF response of 21 recreationally active young adults (11 male, 10 female, mean age 22.1 years) after 47 Hz and 10 min LV to the calf, with and without antihistamine medication (180 mg Fexofenadine). Each participant received both control (no antihistamine) and antihistamine (treatment) conditions separated by at least 24 h. BF ultrasound measurements (mean and peak blood velocity, volume flow, popliteal diameter, and heart rate) were taken before LV therapy and periodically for 19 min post LV. Using a cell means mixed model, we found that LV significantly increased the control mean blood velocity immediately post LV but did not significantly increase the antihistamine mean blood velocity immediately post LV. Therefore, we hypothesize that a primary mechanism of LV increase in BF is histamine release from mechano-sensing mast cells, and that this response is force-dependent.
Free-Vibration Analysis for Truncated Uflyand–Mindlin Plate Models: An Alternative Theoretical Formulation
De Rosa M.A., Elishakoff I., Lippiello M.
Q2
MDPI
Vibration, 2024, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
Plates are flat structural elements whose thickness is small in relation to the size of the surface. Their use may include engine foundations, reinforced concrete bridge elements or parts of various floating structures. Consequently, knowledge of their mechanical behavior under static and dynamic loads is of primary importance in engineering applications and of interest from a structural point of view. As a result, numerous works existing in the literature have investigated the mechanical properties of plates using various plate models, such as Reissner’s theory, Levinson’s theory, Kirchhoff’s theory and Mindlin’s theory, and their static and dynamic behavior has been examined. In the present paper the truncated Uflyand–Mindlin plate equation is proposed. According to Uflyand–Mindlin theory, an alternative theoretical formulation is presented for the free-vibration analysis of plates, and the equations of motion and the general corresponding boundary conditions are derived. This paper develops the truncated Uflyand–Mindlin plate equation, i.e., without the fourth-order derivative, by means of the direct method and variational formulation. The first-order shear deformable plate theory developed by Elishakoff, which takes into account rotational inertia and shear deformation and does not include a fourth-order time derivative, is variationally derived here. This derivation complements that performed by Mindlin some 70 years ago. The innovative aspect of the suggested strategy is that variational and direct methods for studying plate dynamics are analogous. Finding the third equation of the reduced Uflyand–Mindlin equations, the accompanying boundary conditions and their mathematical resemblance are the goals of the presented formulations. In order to solve the dynamic equilibrium problem of a truncated Uflyand–Mindlin equation via a variational formulation, it is demonstrated that the differential equations and the corresponding boundary conditions have the same form as those found using the direct technique. This paper successfully completes this task. Finally, in order to validate the effectiveness and correctness of the proposed procedure, a numerical example of the case of a plate simply supported at all four ends is proposed.
Modes of Vibration in Basketball Rims and Backboards and the Energy Rebound Testing Device
Winarski D., Nygren K.P., Winarski T.
Q2
MDPI
Vibration, 2023, цитирований: 2,
open access Open access ,
PDF, doi.org, Abstract
Six mode shapes, including bending and torsion, were documented for five different basketball rims and backboards at the United States Military Academy, West Point, New York, NY, USA. The frequency and damping ratio of each mode shape were also determined. The empirical process began with the time-domain excitation and response of each rim-backboard system. The impulse of excitation came from an impact hammer separately applied sequentially to each node. The sinusoidal response was gathered from an accelerometer at a fixed location (node 1). Each time-domain excitation response was then converted to a frequency-domain Bode plot for each node by a Brüel & Kjær 2034 Signal Analyzer, giving transfer functions of output/input versus frequency. Structural Measurements System (SMS) StarStruc software was used to fit mode shapes to the Bode plots. Each of the six mode shapes was fitted to the Bode plots of each node at a specific modal frequency. Each of the six mode shapes was a function of the locations of the nodes, and the Bode plots gathered at each node. The first and second modes were critical for showing that the Energy Rebound Testing Device statistically correlated with the energy transferred to the rim and backboard. A known perturbation mass was selectively attached to the rim to help isolate the dynamic masses and spring rates for the rim and backboard and to ascertain that the kinetic energy transferred to the rim had a 95.67% inverse correlation with rim stiffness.
Usability and Vibration Analysis of a Low-Profile Automatic Powered Wheelchair to Motor Vehicle Docking System
Lee C.D., Daveler B.J., Candiotti J.L., Cooper R., Sivakanthan S., Deepak N., Grindle G.G., Cooper R.A.
Q2
MDPI
Vibration, 2023, цитирований: 0,
open access Open access ,
PDF, doi.org, Abstract
The QLX is a low-profile automatic powered wheelchair docking system (WDS) prototype developed to improve the securement and discomfort of wheelchair users when riding in vehicles. The study evaluates the whole-body vibration effects between the proposed QLX and another WDS (4-point tiedown system) following ISO 2631-1 standards and a systematic usability evaluation. Whole-body vibration analysis was evaluated in wheelchairs using both WDS to dock in a vehicle while riding on real-world surfaces. Also, participants rated the usability of each WDS while driving a wheelchair and while riding in a vehicle in driving tasks. Both WDSs showed similar vibration results within the vibration health-risk margins; but shock values below health-risk margins. Fifteen powered wheelchair users reported low task load demand to operate both WDS; but better performance to dock in vehicles with the QLX (p = 0.03). Also, the QLX showed better usability (p < 0.01), less discomfort (p’s < 0.05), and greater security compared to the 4-point tiedown while riding in a vehicle (p’s < 0.05). Study findings indicate that both WDS maintain low shock exposure for wheelchair users while riding vehicles, but a better performance overall to operate the QLX compared to the 4-point tiedown system; hence enhancing user’s autonomy to dock in vehicles independently.
Measurement and Analysis of Crowdsourced Vehicle Vibration Levels during Last Mile Delivery Segments for Parcel Shipments
Dunno K., Chavan P.
Q2
MDPI
Vibration, 2022, цитирований: 2,
open access Open access ,
PDF, doi.org, Abstract
Crowdsourced logistics has emerged as a delivery channel for many single-parcel packages. As a result, this logistics network has introduced personal passenger vehicles as a means to transport parcels during last mile delivery segments. To understand this network’s vibration levels and cargo capacity restraints, four vehicle types (a sedan, sports sedan, compact SUV and full-size SUV) commonly used in crowdsourced logistics deliveries were selected for measurement and analysis. This study shows that the vibration levels were significantly higher in the vertical axis and that the overall vibration energy increased as vehicle speed increased, except in the sedan. The sedan and SUV vehicles showed power spectral density peak frequencies in the low-frequency range, occurring at approximately 2 Hz, matching previous studies using similar vehicles. The vibration levels were greatest in the sports sedan and lowest in the sedan. The recorded vibration events showed a right-skewed heavy-tailed distribution and were non-Gaussian.
Speed-Dependent Eigenmodes for Efficient Simulation of Transverse Rotor Vibration
Kluger J., Crevier L., Udengaard M.
Q2
MDPI
Vibration, 2022, цитирований: 2,
open access Open access ,
PDF, doi.org, Abstract
Accurate, computationally efficient simulations enable engineers to design high-performing, cost-efficient, lightweight machines that can leverage models of predictive controls and digital twin predictive maintenance schedules. This study demonstrates a new speed-dependent eigenmode method for accurately and efficiently simulating shaft transverse vibrations. The method involves first independently computing shaft eigenmodes over a range of operating speeds, then correlating the eigenmodes across the different speeds during compilation, and finally adjusting modal properties gradually in accordance with a lookup method during simulation. The new method offers several distinct advantages over the traditional static eigenmodes and Craig-Bampton methods. The new method maintains accuracy over a large range of shaft rotation speeds whereas the static eigenmodes method does not. The new method typically requires fewer modal degrees of freedom than the Craig-Bampton method. Whereas the Craig-Bampton method is limited to modeling changes at the boundaries, the new method is suitable for modeling changing body properties as well as boundary-based changes. For this paper, a fluid-bearing-supported 10 MW direct-drive wind turbine drive shaft is tested virtually in a simulation model developed in Simscape™ Driveline™. Using the simulation statistics, this study compares the accuracy and computational efficiency of the speed-dependent eigenmode method to the traditional finite lumped element, static eigenmode, and Craig–Bampton methods. This paper shows that the new method simulates the chosen system 5 times faster than the traditional lumped mass method and 2.4 times faster than the Craig-Bampton method.
Prediction of Voice Fundamental Frequency and Intensity from Surface Electromyographic Signals of the Face and Neck
Vojtech J.M., Mitchell C.L., Raiff L., Kline J.C., De Luca G.
Q2
MDPI
Vibration, 2022, цитирований: 4,
open access Open access ,
PDF, doi.org, Abstract
Silent speech interfaces (SSIs) enable speech recognition and synthesis in the absence of an acoustic signal. Yet, the archetypal SSI fails to convey the expressive attributes of prosody such as pitch and loudness, leading to lexical ambiguities. The aim of this study was to determine the efficacy of using surface electromyography (sEMG) as an approach for predicting continuous acoustic estimates of prosody. Ten participants performed a series of vocal tasks including sustained vowels, phrases, and monologues while acoustic data was recorded simultaneously with sEMG activity from muscles of the face and neck. A battery of time-, frequency-, and cepstral-domain features extracted from the sEMG signals were used to train deep regression neural networks to predict fundamental frequency and intensity contours from the acoustic signals. We achieved an average accuracy of 0.01 ST and precision of 0.56 ST for the estimation of fundamental frequency, and an average accuracy of 0.21 dB SPL and precision of 3.25 dB SPL for the estimation of intensity. This work highlights the importance of using sEMG as an alternative means of detecting prosody and shows promise for improving SSIs in future development.
Deep Machine Learning for Acoustic Inspection of Metallic Medium
Jarreau B., Yoshida S., Laprime E.
Q2
MDPI
Vibration, 2022, цитирований: 3,
open access Open access ,
PDF, doi.org, Abstract
Acoustic non-destructive testing is widely used to detect signs of damage. However, an experienced technician is typically responsible for interpreting the result, and often the evaluation varies depending on the technician’s opinion. The evaluation is especially challenging when the acoustic signal is analyzed in the near field as Fresnel range diffraction complicates the data. In this study, we propose a Convolutional Neural Network (CNN) algorithm to detect anomalies bearing in mind its future application to micro-scale specimens such as biomedical materials. Data are generated by emitting a continuous sound wave at a single frequency through a metal specimen with a sub-millimeter anomaly and collecting the transmitted signal at several lateral locations on the opposite side (the observation plane) of the specimen. The distance between the anomaly and the observation plane falls in the quasi Fresnel diffraction regime. The use of transmitted signals is essential to evaluate the phase shift due to the anomaly, which contains information about the substance in the anomaly. We have developed a seven-layered CNN to analyze the acoustic signal in the frequency domain. The CNN takes spectrograms representing the change in the amplitude and phase of the Fourier transform over the lateral position on the observation plane as input and classifies the anomaly into nine classes in association with the lateral location of the anomaly relative to the probing signal and the material of the anomaly. The CNN performed excellently demonstrating the validation accuracy as high as 99.9%. This result clearly demonstrates CNN’s ability to extract features in the input signal that are undetectable to humans.
Vertical and Side-Alternating Whole Body Vibration Platform Parameters Influence Lower Extremity Blood Flow and Muscle Oxygenation
Lyons K.D., Parks A.G., Dadematthews O.D., McHenry P.A., Sefton J.M.
Q2
MDPI
Vibration, 2022, цитирований: 1,
open access Open access ,
PDF, doi.org, Abstract
This study directly compared blood flow and oxygenation during six treatment parameters used with vertical and side alternating whole body vibration (WBV). Twenty-seven healthy adults were randomized into the vertical or side-alternating (vibration type) WBV group. Participants completed three WBV sessions a week apart, 5 sets of 1 min on/off, at 3 conditions (Vertical: 30 Hz and 4 mm, 40 Hz and 2 mm, 45 Hz and 4 mm; Side-alternating: 10 Hz and 4 mm, 18 Hz and 3 mm and 26 Hz and 2 mm). Blood flow velocity and popliteal artery diameter, muscle oxygenation, skin temperature, heart rate and blood pressure were assessed. Muscle oxygenation was significantly increased for all vibration frequencies and types following two minutes of WBV (14.78%, p = 0.02) and continued until immediately after the cessation of WBV (24.7%, p < 0.001). WBV also increased heart rate (23.9%, p < 0.001) and systolic blood pressure (8.9%, p < 0.001) regardless of frequency and vibration type. Side-alternating and vertical WBV increased muscle oxygenation and heart rate in healthy participants completing an isometric squat. Muscle oxygenation was not increased until the second vibration set indicating the amount of time spent on the platform may have a significant effect on increases in blood flow.
Topological Acoustic Sensing Using Nonseparable Superpositions of Acoustic Waves
Lata T.D., Deymier P.A., Runge K., Clark W.
Q2
MDPI
Vibration, 2022, цитирований: 6,
open access Open access ,
PDF, doi.org, Abstract
We introduce a method, topological acoustic sensing, which exploits changes in the geometric phase of nonseparable coherent superpositions of acoustic waves to sense mass defects in arrays of coupled acoustic waveguides. Theoretical models and experimental results shed light on the origin of the behavior and sensitivity of the geometric phase due to the presence of mass defects. The choice of the coherent superposition of waves used to probe the defects as well as the mathematical representation determining the topological characteristics of its space of states are shown to be critical in maximizing the sensitivity of the topological acoustic sensing method.
Observer-Based H∞ Controller Design for High Frequency Stick-Slip Vibrations Mitigation in Drill-String of Rotary Drilling Systems
Riane R., Doghmane M.Z., Kidouche M., Djezzar S.
Q2
MDPI
Vibration, 2022, цитирований: 11,
open access Open access ,
PDF, doi.org, Abstract
The drilling process is among the most crucial steps in exploration and production activities in the petroleum industry. It consists of using mechanical mechanisms to crush rocks by the drill bit to pass through the different geological layers. The drill-string continuously transforms the rotational movement from the top drive motor to the drill bit through the drill pipes. Due to the strong interactions with the rocks, aggressive vibrations can arise in the drill-string in its three dimensions, and consequently, this may create three types of synchronous vibrations: axial, lateral, and torsional. The severe status of the latter is known as the stick-slip phenomenon, and is the most common in rotary drilling systems. Based on field observations, it has been inferred that the high frequency stick-slip vibrations may lead to drill-string fatigues and even to premature rupture. In the best case, it reduces the drilling efficiency by decreasing the rate of penetration, due to which the drilling operations become proportionally expensive. The main novelties of this research work are the design of an H∞ observer-based controller to mitigate the high frequency stick-slip vibrations, and the quantitative analysis of the vibrations’ severity for ten degrees of freedom model. The observer is designed to estimate the non-measurable rotational velocity of the drill bit due to the severity of the vibrations, while the controller is dedicated to suppressing the vibrations by using the top drive inputs. Thus, many scenarios have been considered to test and analyze the observer performance and the controller robustness. Furthermore, a comparison with the LQG observer-based controller has been conducted, where H∞ has demonstrated better efficiency in suppressing the stick-slip vibrations under unstructured perturbations.
Analysis of Whole-Body Vibration Using Electric Powered Wheelchairs on Surface Transitions
Candiotti J.L., Neti A., Sivakanthan S., Cooper R.A.
Q2
MDPI
Vibration, 2022, цитирований: 6,
open access Open access ,
PDF, doi.org, Abstract
Wheelchair users are exposed to whole-body vibration (WBV) when driving on sidewalks and in urban environments; however, there is limited literature on WBV exposure to power wheelchair users when driving during daily activities. Further, surface transitions (i.e., curb-ramps) provide wheelchair accessibility from street intersections to sidewalks; but these require a threshold for water drainage. This threshold may induce high WBV (i.e., root-mean-square and vibration-daily-value accelerations) when accessibility guidelines are not met. This study analyzed the WBV effects on power wheelchairs with passive suspension when driving over surfaces with different thresholds. Additionally, this study introduced a novel power wheelchair with active suspension to reduce WBV levels on surface transitions. Three trials were performed with a commercial power wheelchair with passive suspension, a novel power wheelchair with active suspension, and the novel power wheelchair without active suspension driving on surfaces with five different thresholds. Results show no WBV difference among EPWs across all surfaces. However, the vibration-dose-value increased with higher surface thresholds when using the passive suspension while the active suspension remained constant. Overall, the power wheelchair with active suspension offered similar WBV effects as the passive suspension. While significant vibration-dose-value differences were observed between surface thresholds, all EPWs maintained WBV values below the ISO 2631-1 health caution zone.
Nonintrusive Nonlinear Reduced Order Models for Structures in Large Deformations: Validations to Atypical Structures and Basis Construction Aspects
Wang X., Perez R.A., Wainwright B., Wang Y., Mignolet M.P.
Q2
MDPI
Vibration, 2022, цитирований: 5,
open access Open access ,
PDF, doi.org, Abstract
The focus of this investigation is on reduced order models (ROMs) of the nonlinear geometric response of structures that are built nonintrusively, i.e., from standard outputs of commercial finite element codes. Several structures with atypical loading, boundary conditions, or geometry are considered to not only support the broad applicability of these ROMs but also to exemplify the different steps involved in determining an appropriate basis for the response. This basis is formed here as a combination of linear vibration modes and dual modes, and some of the steps involved follow prior work; others are novel aspects, all of which are covered in significant detail to minimize the expertise needed to develop these ROMs. The comparisons of the static and dynamic responses of these structures predicted by the ROMs and by the underlying finite element models demonstrate the high accuracy that can be achieved with the ROMs, even in the presence of significant nonlinearity.
Cobalt Бета
ru en