scholarly journals Analysis of Vibration Monitoring Data of Flexible Suspension Lifting Structure Based on Time-Varying Theory

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6586
Author(s):  
Qifeng Peng ◽  
Peng Xu ◽  
Hong Yuan ◽  
Haixia Ma ◽  
Jianghong Xue ◽  
...  
Keyword(s):  
Transverse Vibration ◽  
Longitudinal Vibration ◽  
Low Frequency ◽  
Elastic Interaction ◽  
Vibration Monitoring ◽  
Test Results ◽  
Longitudinal Vibrations ◽  
High Frequency Region ◽  
Power Spectral ◽  
Short Time

An elevator is a typical flexible lifting machine. In order to monitor the vibration of elevator structure, the vibration characteristics of an elevator with a traction ratio of 1:1 has been tested experimentally. Sensors were arranged on the platform frame, car roof, and hoist rope to test the vibrations of the elevator in both ascending and descending conditions. The transverse, longitudinal, and coupled transverse-longitudinal vibrations were compared and analyzed. Further, the short-time Fourier transform (STFT) method was used to examine the power spectral density (PSD) of the test results, and the main frequency distribution and influencing factors of the vibration of elevator components were investigated. The results revealed that the transverse and longitudinal vibrations of the platform frame were low-frequency vibrations, which was attributed to the elastic interaction between the platform frame and the car frame. The form and amplitude of longitudinal vibration of the car frame were basically consistent with those of the platform frame, but PSD of the transverse vibration had an obvious peak in the high-frequency region. The transverse and longitudinal vibration frequencies of the hoist rope were higher. Furthermore, the peak PSD value of transverse vibration of the hoist rope was 421 times larger than that of the car frame, so a small disturbance at the end of the rope could lead to a huge disturbance in the center of the rope. Overall, this study provides useful insights on designing an elevator monitoring sensor and relevant data processing.

On the Assignment and Directional Dispersion of Polar Phonon Modes in K3Cu(CN)4 and K3Ag(CN)4

1974 ◽  
Vol 29 (7) ◽  
pp. 1011-1016
Author(s):  
W. Nitsch ◽  
H. J. Falge ◽  
R. Claus
Keyword(s):  
Light Scattering ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Region ◽  
Longitudinal Vibrations ◽  
Phonon Modes ◽  
High Frequency Region ◽  
Single Crystalline ◽  
Scattering Measurements ◽  
Stretching Vibrations

Polar phonon modes in single crystalline K3Cu(CN)4 and K3Ag(CN)4 have been experimentally studied by light scattering. Measurements at 293, 82 and 6 K made possible assignments in the low frequency region from 0 to about 700 cm-1 and the high frequency region from 2030 to about 2100 cm-1 originating from the C≡N stretching vibrations. Directional dispersion due to the anisotropy of K3Cu(CN)4 has been studied and allowed the identification of the transversal and longitudinal vibrations in the high frequency region. IR-reflectivity measurements, partly on the basis of the ATR-method, have been used in order to support the assignments in this region.

A Standing Wave Ultrasonic Motor Using Longitudinal Vibration Transducers

2011 ◽  
Vol 474-476 ◽  
pp. 661-665
Author(s):  
Jun Kao Liu ◽  
Tao Xie ◽  
Wei Shan Chen ◽  
Chang Hua Jia
Keyword(s):  
Standing Wave ◽  
Longitudinal Vibration ◽  
Ultrasonic Motor ◽  
Test Results ◽  
Longitudinal Vibrations ◽  
Bending Vibration ◽  
Harmonic Vibrations ◽  
Fem Method ◽  
New Type ◽  
Working Principle

A new type standing wave ultrasonic motor is proposed in this study. In this design, three longitudinal vibration transducers are clamped on the inner side of a ring with driving teeth by screws. Bending standing wave can be generated in the ring by the longitudinal vibrations of the transducers. Thus, oblique linear simple harmonic vibrations are formed on the teeth, which can drive the rotor by frictional force. The structure and working principle of the proposed design are introduced. The motor is designed and analyzed by using FEM method. A standing wave is gained after the degeneration between the bending vibration of the ring and the longitudinal vibration of the transducer. The test results of the prototype motor verify the feasibility of the proposed design.

scholarly journals On the longitudinal vibration of the railway bogie

2019 ◽  
Vol 290 ◽  
pp. 08008
Author(s):  
Mădălina Dumitriu ◽  
Marius Alin Gheţi
Keyword(s):  
Coupling Effect ◽  
Longitudinal Vibration ◽  
Longitudinal Motion ◽  
Vertical Acceleration ◽  
Vibration Modes ◽  
Vibration Level ◽  
Longitudinal Vibrations ◽  
Power Spectral ◽  
Track System ◽  
Vertical Displacements

This paper examines the influence of the rebound longitudinal motion of the bogie upon the vibration behaviour in the bogie. The analysis is based on the results of the numerical simulations developed on the basis of a general model with a nine-degree freedom of the bogie-track system, which takes into account the rigid vibration modes of the bogie – bounce, pitch and rebound, vertical and longitudinal displacements of the wheels, vertical displacements of the rails, and the wheel-rail contact elasticity, and a simplified model that does not consider the bogie longitudinal vibrations of rebound. The bogie vibration behaviour is assessed based on the power spectral density of the vertical acceleration and root mean square of vertical acceleration. It is highlighted the increase of the vibration level of the bogie due to the coupling effect between the pitch and rebound longitudinal vibrations, which, however, does not exceed 3-4% in terms of acceleration.

scholarly journals Electromagnetic power of lightning superbolts from Earth to space

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
J.-F. Ripoll ◽  
T. Farges ◽  
D. M. Malaspina ◽  
G. S. Cunningham ◽  
E. H. Lay ◽  
...  
Keyword(s):  
Low Frequency ◽  
Optical Emission ◽  
High Energy ◽  
Very Low Frequency ◽  
Electromagnetic Power ◽  
Power Spectral ◽  
High Energy Tail ◽  
Van Allen Probes ◽  
Long Time ◽  
Low Frequency Waves

AbstractLightning superbolts are the most powerful and rare lightning events with intense optical emission, first identified from space. Superbolt events occurred in 2010-2018 could be localized by extracting the high energy tail of the lightning stroke signals measured by the very low frequency ground stations of the World-Wide Lightning Location Network. Here, we report electromagnetic observations of superbolts from space using Van Allen Probes satellite measurements, and ground measurements, and with two events measured both from ground and space. From burst-triggered measurements, we compute electric and magnetic power spectral density for very low frequency waves driven by superbolts, both on Earth and transmitted into space, demonstrating that superbolts transmit 10-1000 times more powerful very low frequency waves into space than typical strokes and revealing that their extreme nature is observed in space. We find several properties of superbolts that notably differ from most lightning flashes; a more symmetric first ground-wave peak due to a longer rise time, larger peak current, weaker decay of electromagnetic power density in space with distance, and a power mostly confined in the very low frequency range. Their signal is absent in space during day times and is received with a long-time delay on the Van Allen Probes. These results have implications for our understanding of lightning and superbolts, for ionosphere-magnetosphere wave transmission, wave propagation in space, and remote sensing of extreme events.

scholarly journals Modelling of Amplitude Modulated Vocal Fry Glottal Area Waveforms Using an Analysis-by-Synthesis Approach

2021 ◽  
Vol 11 (5) ◽  
pp. 1990
Author(s):  
Vinod Devaraj ◽  
Philipp Aichinger
Keyword(s):  
Voice Quality ◽  
Low Frequency ◽  
Voice Disorder ◽  
Support Vector ◽  
Svm Classifier ◽  
Power Spectral ◽  
Analysis By Synthesis ◽  
Simple Support ◽  
Frequency Modulations ◽  
Synthesis Approach

The characterization of voice quality is important for the diagnosis of a voice disorder. Vocal fry is a voice quality which is traditionally characterized by a low frequency and a long closed phase of the glottis. However, we also observed amplitude modulated vocal fry glottal area waveforms (GAWs) without long closed phases (positive group) which we modelled using an analysis-by-synthesis approach. Natural and synthetic GAWs are modelled. The negative group consists of euphonic, i.e., normophonic GAWs. The analysis-by-synthesis approach fits two modelled GAWs for each of the input GAW. One modelled GAW is modulated to replicate the amplitude and frequency modulations of the input GAW and the other modelled GAW is unmodulated. The modelling errors of the two modelled GAWs are determined to classify the GAWs into the positive and the negative groups using a simple support vector machine (SVM) classifier with a linear kernel. The modelling errors of all vocal fry GAWs obtained using the modulating model are smaller than the modelling errors obtained using the unmodulated model. Using the two modelling errors as predictors for classification, no false positives or false negatives are obtained. To further distinguish the subtypes of amplitude modulated vocal fry GAWs, the entropy of the modulator’s power spectral density and the modulator-to-carrier frequency ratio are obtained.

Fish Attraction with Pulsed Low-Frequency Sound

1968 ◽  
Vol 25 (7) ◽  
pp. 1441-1452 ◽  
Author(s):  
Joseph D. Richard
Keyword(s):  
Acoustic Stimulus ◽  
Low Frequency ◽  
Reef Fishes ◽  
Test Site ◽  
Acoustic Signals ◽  
Commercial Fisheries ◽  
Test Results ◽  
Potential Applications ◽  
Predatory Fishes ◽  
Underwater Television

A series of tests were conducted to determine the effectiveness of pulsed low-frequency acoustic signals for attracting fishes. The acoustic signals were contrived to simulate the hydrodynamically generated disturbances normally associated with active predation. Underwater television was used to observe fish arrivals during both control and test periods. Demersal predatory fishes were successfully attracted although they habituated rapidly to the acoustic stimulus. Members of the families Serranidae, Lutjanidae, and Pomadasyidae were particularly well represented among the fishes attracted. Sharks were also attracted in considerable numbers. Herbivorous reef fishes, although common around the test site, were not attracted. Possible relationships between the test results and the hearing capabilities of fishes are discussed. It is concluded that acoustic attraction techniques have potential applications in certain existing commercial fisheries.

Shock Test and Acceleration Analysis Methods of Marine Diesel Engines to Underwater Explosions

2013 ◽  
Vol 345 ◽  
pp. 64-67
Author(s):  
Jian Hua Zhao ◽  
Rui Bo Zhang ◽  
De Bin Zhu ◽  
Hong Bin Gao
Keyword(s):  
Diesel Engine ◽  
Low Frequency ◽  
Vibration Signal ◽  
Test Methods ◽  
Shock Acceleration ◽  
Test Results ◽  
Shock Test ◽  
Marine Diesel ◽  
Reduction Methods ◽  
Acceleration Analysis

Shock test of marine diesel engine is the important content for ship anti-shock research. Plentiful shock tests of equipments have been carried out abroad, but there is no detailed test methods of diesel engine. According to simulation results, 8-channel acceleration test points are determined. Because diesel engine is working, the measured shock acceleration is interfered by vibration signal. Orthogonal wavelet decomposition and wavelet noise reduction methods are used to separate shock component from test results. The seperated shock component consists of two parts. One is the low-frequency part caused by the shock from diesel foundation and then attenuation through the isolator, the other is the high-frequency part caused by the secondary shock of the retainer.

Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 919-924
Author(s):  
M.S. Jogad ◽  
V.K. Shrikhande ◽  
A.H. Dyama ◽  
L.A. Udachan ◽  
Govind P. Kothiyal
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Low Frequency ◽  
Frequency Region ◽  
Dc Conductivity ◽  
Frequency Range ◽  
High Frequency Region ◽  
Dc Conductivities ◽  
Conductivity Variation ◽  
Different Temperatures

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.

Sleep Stage Assessment Using Power Spectral Indices of Heart Rate Variability With a Simple Algorithm

2012 ◽  
Vol 15 (3) ◽  
pp. 264-272 ◽  
Author(s):  
Keiko Tanida ◽  
Masashi Shibata ◽  
Margaret M. Heitkemper
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Sleep Stage ◽  
Sleep Onset ◽  
Low Frequency ◽  
Simple Algorithm ◽  
Sleep Stages ◽  
Spectral Indices ◽  
Current Form ◽  
Power Spectral

Clinical researchers do not typically assess sleep with polysomnography (PSG) but rather with observation. However, methods relying on observation have limited reliability and are not suitable for assessing sleep depth and cycles. The purpose of this methodological study was to compare a sleep analysis method based on power spectral indices of heart rate variability (HRV) data to PSG. PSG and electrocardiography data were collected synchronously from 10 healthy women (ages 20–61 years) over 23 nights in a laboratory setting. HRV was analyzed for each 60-s epoch and calculated at 3 frequency band powers (very low frequency [VLF]-hi: 0.016–0.04 Hz; low frequency [LF]: 0.04–0.15 Hz; and high frequency [HF]: 0.15–0.4 Hz). Using HF/(VLF-hi + LF + HF) value, VLF-hi, and heart rate (HR) as indices, an algorithm to categorize sleep into 3 states (shallow sleep corresponding to Stages 1 & 2, deep sleep corresponding to Stages 3 & 4, and rapid eye movement [REM] sleep) was created. Movement epochs and time of sleep onset and wake-up were determined using VLF-hi and HR. The minute-by-minute agreement rate with the sleep stages as identified by PSG and HRV data ranged from 32 to 72% with an average of 56%. Longer wake after sleep onset (WASO) resulted in lower agreement rates. The mean differences between the 2 methods were 2 min for the time of sleep onset and 6 min for the time of wake-up. These results indicate that distinguishing WASO from shallow sleep segments is difficult using this HRV method. The algorithm's usefulness is thus limited in its current form, and it requires additional modification.

scholarly journals Spiral Sound Wave Transducer Based on the Longitudinal Vibration

Sensors ◽  
2018 ◽  
Vol 18 (11) ◽  
pp. 3674 ◽  
Author(s):  
Wei Lu ◽  
Yu Lan ◽  
Rongzhen Guo ◽  
Qicheng Zhang ◽  
Shichang Li ◽  
...  
Keyword(s):  
Sound Wave ◽  
Longitudinal Vibration ◽  
Three Dimensional ◽  
Low Frequency ◽  
Sound Field ◽  
Field Measurements ◽  
Sound Waves ◽  
Underwater Sound ◽  
Three Dimensional Finite Element ◽  
Wave Transducer

A spiral sound wave transducer comprised of longitudinal vibrating elements has been proposed. This transducer was made from eight uniform radial distributed longitudinal vibrating elements, which could effectively generate low frequency underwater acoustic spiral waves. We discuss the production theory of spiral sound waves, which could be synthesized by two orthogonal acoustic dipoles with a phase difference of 90 degrees. The excitation voltage distribution of the transducer for emitting a spiral sound wave and the measurement method for the transducer is given. Three-dimensional finite element modeling (FEM)of the transducer was established for simulating the vibration modes and the acoustic characteristics of the transducers. Further, we fabricated a spiral sound wave transducer based on our design and simulations. It was found that the resonance frequency of the transducer was 10.8 kHz and that the transmitting voltage resonance was 140.5 dB. The underwater sound field measurements demonstrate that our designed transducer based on the longitudinal elements could successfully generate spiral sound waves.

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