Vibration最新文献_第7页

Unsteady Aerodynamic Lift Force on a Pitching Wing: Experimental Measurement and Data Processing 俯仰机翼非定常气动升力的实验测量和数据处理

Vibration Pub Date : 2023-01-04 DOI: 10.3390/vibration6010003

P. Z. Csurcsia, M. F. Siddiqui, M. Runacres, T. De Troyer

{"title":"Unsteady Aerodynamic Lift Force on a Pitching Wing: Experimental Measurement and Data Processing","authors":"P. Z. Csurcsia, M. F. Siddiqui, M. Runacres, T. De Troyer","doi":"10.3390/vibration6010003","DOIUrl":"https://doi.org/10.3390/vibration6010003","url":null,"abstract":"This work discusses the experimental challenges and processing of unsteady experiments for a pitching wing in the low-speed wind tunnel of the Vrije Universiteit Brussel. The setup used for unsteady experiments consisted of two independent devices: (a) a position control device to steer the pitch angle of the wing, and (b) a pressure measurement device to measure the aerodynamic loads. The position control setup can pitch the wing for a range of frequencies, amplitude, and offset levels. In this work, a NACA-0018 wing profile was used with an aspect ratio of 1.8. The position control and the pressure measurement setups operate independently of each other, necessitating advanced signal processing techniques to synchronize the pitch angle and the lift force. Furthermore, there is a (not well-documented) issue with the (sampling) clock frequency of the pressure measurement setup, which was resolved using a fully automated spectral analysis technique. The wing was pitched using a simple harmonic sine excitation signal at eight different offset levels (between 6° and 21°) for a fixed amplitude variation (std) of 6°. At each offset level, the wing was pitched at five different frequencies between 0.1 Hz and 2 Hz (that correspond to reduced frequencies k ranging from 0.006 to 0.125). All the experiments were conducted at a fixed chord-based Reynolds number of 2.85 × 105. The choice of operating parameters invokes the linear and nonlinear behavior of the wing. The linear unsteady measurements agreed with the analytical results. The unsteady pressure measurements at higher offset levels revealed the nonlinear aerodynamic phenomenon of dynamic stall. This confirms that a nonlinear and dynamic model is required to capture the salient characteristics of the lift force on a pitching wing.","PeriodicalId":75301,"journal":{"name":"Vibration","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-01-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43007959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Bearing Fault Diagnosis Based on Multi-Scale CNN and Bidirectional GRU 基于多尺度CNN和双向GRU的轴承故障诊断

Vibration Pub Date : 2022-12-30 DOI: 10.3390/vibration6010002

Taher Saghi, D. Bustan, S. S. Aphale

引用次数: 3

Vibration Characteristics Control of Resonance Point in Vehicle: Fundamental Considerations of Control System without Displacement and Velocity Information 车辆共振点振动特性控制：无位移和速度信息控制系统的基本考虑

Vibration Pub Date : 2022-12-26 DOI: 10.3390/vibration6010001

K. Ikeda, J. Kuroda, Daigo Uchino, K. Ogawa, A. Endo, T. Kato, H. Kato, T. Narita

{"title":"Vibration Characteristics Control of Resonance Point in Vehicle: Fundamental Considerations of Control System without Displacement and Velocity Information","authors":"K. Ikeda, J. Kuroda, Daigo Uchino, K. Ogawa, A. Endo, T. Kato, H. Kato, T. Narita","doi":"10.3390/vibration6010001","DOIUrl":"https://doi.org/10.3390/vibration6010001","url":null,"abstract":"The deterioration of ride comfort in ultra-compact vehicles has recently become an increasing concern. Active seat suspension was proposed to improve the ride comfort of ultra-compact vehicles. An active seat suspension is a vibration control device that is easily installed. The general vibration control system of the active seat suspension is fed back to the displacement and velocity by integrating the measured seat acceleration. This control has problems, such as control delay and deviation by integration. In this study, we focused on vibration control using acceleration directly. First, we established a control model that feeds back the acceleration to terminate the error occurring in the integral process and investigated the change in vibration characteristics in the case where the feedback gain of acceleration was changed. Second, the control system was analyzed to investigate the performance of the control based on the frequency characteristics. As a result, it was confirmed that the frequency response changes when the feedback gain is changed. In acceleration feedback control, ride comfort was improved by selecting a proper feedback gain because the characteristics of frequency were changed by the gain.","PeriodicalId":75301,"journal":{"name":"Vibration","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45717365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Vibration Characteristics of Flexible Steel Plate on Proposed Magnetic Levitation System Using Gravity 柔性钢板在重力磁悬浮系统中的振动特性

Vibration Pub Date : 2022-12-18 DOI: 10.3390/vibration5040054

A. Endo, Rintaro Itoyama, J. Kuroda, Daigo Uchino, K. Ogawa, K. Ikeda, T. Kato, T. Narita, H. Kato

{"title":"Vibration Characteristics of Flexible Steel Plate on Proposed Magnetic Levitation System Using Gravity","authors":"A. Endo, Rintaro Itoyama, J. Kuroda, Daigo Uchino, K. Ogawa, K. Ikeda, T. Kato, T. Narita, H. Kato","doi":"10.3390/vibration5040054","DOIUrl":"https://doi.org/10.3390/vibration5040054","url":null,"abstract":"Flexible steel plates are generally transported by rollers; however, the contact between the rollers and the steel plate degrades the surface quality of the plate. To solve this problem, noncontact transportation of steel plates using electromagnetic force has been proposed. However, ultrathin flexible steel plates can easily fall owing to deflection. A magnetic levitation system using electromagnets installed in the horizontal direction has also been proposed to improve the levitation performance of a conventional system. However, it is difficult to control vibrations with such a system because flexible steel plates are elastically deformed into complex shapes by gravity. Therefore, an electromagnetic levitation system was proposed, wherein electromagnets were installed near the edge of the steel plate such that it could be controlled with noncontact grip, such as by allowing one side of the steel plate to hang. This system is expected to improve levitation stability because the moment of inertia increases with vertical levitation and simplifies the control system. In addition, this system actively uses gravity acting on a steel plate to decrease its deflection. The use of gravity to suppress deflection is novel. In this study, the feasibility of magnetic levitation using the proposed system was investigated using magnetic field analysis. Its usefulness was investigated experimentally using a constructed magnetic levitation system. In addition, it was found that a magnetic levitation system that maintains the standing position generates a peculiar vibration.","PeriodicalId":75301,"journal":{"name":"Vibration","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43774912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Free Vibrations of Multi-Degree Structures: Solving Quadratic Eigenvalue Problems with an Excitation and Fast Iterative Detection Method 多自由度结构的自由振动:用激励和快速迭代检测方法求解二次特征值问题

Vibration Pub Date : 2022-12-18 DOI: 10.3390/vibration5040053

Chein-Shan Liu, C. Kuo, Chih‐Wen Chang

{"title":"Free Vibrations of Multi-Degree Structures: Solving Quadratic Eigenvalue Problems with an Excitation and Fast Iterative Detection Method","authors":"Chein-Shan Liu, C. Kuo, Chih‐Wen Chang","doi":"10.3390/vibration5040053","DOIUrl":"https://doi.org/10.3390/vibration5040053","url":null,"abstract":"For the free vibrations of multi-degree mechanical structures appeared in structural dynamics, we solve the quadratic eigenvalue problem either by linearizing it to a generalized eigenvalue problem or directly treating it by developing the iterative detection methods for the real and complex eigenvalues. To solve the generalized eigenvalue problem, we impose a nonzero exciting vector into the eigen-equation, and solve a nonhomogeneous linear system to obtain a response curve, which consists of the magnitudes of the n-vectors with respect to the eigen-parameters in a range. The n-dimensional eigenvector is supposed to be a superposition of a constant exciting vector and an m-vector, which can be obtained in terms of eigen-parameter by solving the projected eigen-equation. In doing so, we can save computational cost because the response curve is generated from the data acquired in a lower dimensional subspace. We develop a fast iterative detection method by maximizing the magnitude to locate the eigenvalue, which appears as a peak in the response curve. Through zoom-in sequentially, very accurate eigenvalue can be obtained. We reduce the number of eigen-equation to n−1 to find the eigen-mode with its certain component being normalized to the unit. The real and complex eigenvalues and eigen-modes can be determined simultaneously, quickly and accurately by the proposed methods.","PeriodicalId":75301,"journal":{"name":"Vibration","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49104830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Fourier Series Approximation of Vertical Walking Force-Time History through Frequentist and Bayesian Inference 基于频率和贝叶斯推断的垂直行走力时程的傅立叶级数逼近

Vibration Pub Date : 2022-12-09 DOI: 10.3390/vibration5040052

A. Peters, V. Racic, S. Z̆ivanović, J. Orr

{"title":"Fourier Series Approximation of Vertical Walking Force-Time History through Frequentist and Bayesian Inference","authors":"A. Peters, V. Racic, S. Z̆ivanović, J. Orr","doi":"10.3390/vibration5040052","DOIUrl":"https://doi.org/10.3390/vibration5040052","url":null,"abstract":"The increased ambition of architects coupled with advancements in structural materials, as well as the rapidly increasing pressure on civil engineering sector to reduce embodied carbon, have resulted in longer spans and more slender pedestrian structures. These structures often have one or more low natural frequencies in the range of human walking accompanied with low modal masses and damping ratios. Thus, they are prone to excessive and often resonant vibrations that may compromise the serviceability limit state. Principally the uncertainty in prediction of the vibration serviceability limit state mainly originates from unreliable estimates of pedestrian loading. The key rationale behind this situation is the limited mathematical characterisation featuring in current design codes and guidelines pertinent to pedestrian-induced loading. The Fourier approximation is typically used to describe individual walking forces. Historically, such models are based on limited experimental data and deterministic mathematical descriptions. Current industry used load models featured in design codes and guidelines have been shown to incorporate inherent bias through limited intra-subject variation and poor correlation with real walking loads. This paper presents an improved Fourier model of vertical walking force across multiple harmonics, presented in a Bayesian and Frequentist statistical parameterisation. They are derived using the most comprehensive dataset to date, comprising of over ten hours of continuous vertical walking force signals. Dissimilar to previous Fourier models, the proposed models attempt to encapsulate the surround energy leakage around harmonic integers with a singular value. The proposed models provide consistently lower force amplitudes than any previous model and is shown to be more representative of real walking. The proposed model provides a closer approximation of a structural acceleration than any other similar Fourier-based model. The proposed model provides further evidence to combine the so called high and low frequency load models.","PeriodicalId":75301,"journal":{"name":"Vibration","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49128749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Seat-To-Head Transmissibility Responses of Seated Human Body Coupled with Visco-Elastic Seats 粘弹性座椅下人体座椅对头部传递率的响应

Vibration Pub Date : 2022-12-05 DOI: 10.3390/vibration5040051

K. Dewangan, Yu-Ta Yao, S. Rakheja

引用次数: 2

Prediction of Voice Fundamental Frequency and Intensity from Surface Electromyographic Signals of the Face and Neck. 基于面部和颈部肌电信号的声音基频和强度预测。

Vibration Pub Date : 2022-12-01 Epub Date: 2022-10-13 DOI: 10.3390/vibration5040041

Jennifer M Vojtech, Claire L Mitchell, Laura Raiff, Joshua C Kline, Gianluca De Luca

{"title":"Prediction of Voice Fundamental Frequency and Intensity from Surface Electromyographic Signals of the Face and Neck.","authors":"Jennifer M Vojtech, Claire L Mitchell, Laura Raiff, Joshua C Kline, Gianluca De Luca","doi":"10.3390/vibration5040041","DOIUrl":"https://doi.org/10.3390/vibration5040041","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":75301,"journal":{"name":"Vibration","volume":"5 4","pages":"692-710"},"PeriodicalIF":0.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9592063/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"40651187","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Linear Matrix Inequality Approach to Designing Damping and Tracking Control for Nanopositioning Application 用于纳米定位应用的阻尼和跟踪控制设计的线性矩阵不等式方法

Vibration Pub Date : 2022-11-29 DOI: 10.3390/vibration5040050

A. K. Babarinde, S. S. Aphale

引用次数: 0

Experimental Consideration on Suppression Effect of Elastic Vibration in Electromagnetic Levitation System for Flexible Thin Steel Plate with Curvature 弯曲柔性薄板电磁悬浮系统弹性振动抑制效果的实验研究

Vibration Pub Date : 2022-11-17 DOI: 10.3390/vibration5040048

K. Ogawa, Riku Miyazaki, Yamato Uchida, I. Kobayashi, J. Kuroda, Daigo Uchino, K. Ikeda, T. Kato, A. Endo, T. Narita, H. Kato

引用次数: 3