scholarly journals Vibration Induced by Subway Trains: Open-Trench Mitigation Analysis in the Time and Frequency Domains

2018 ◽  
Vol 2018 ◽  
pp. 1-16 ◽  
Author(s):  
Wenbo Yang ◽  
Ran Yuan ◽  
Juan Wang
Keyword(s):  
Numerical Simulations ◽  
Frequency Domain ◽  
Frequency Domain Analysis ◽  
Soil Response ◽  
Physical Model Tests ◽  
Frequency Domains ◽  
Trench Isolation ◽  
Open Trench ◽  
Isolation Performance ◽  
Time And Frequency Domains

In this paper, we analyse the mitigation effects of open trenches on the vibrations induced by subway trains. The study is performed by using both physical model tests and numerical simulations. The effectiveness is evaluated by calculating the frequency response function (FRF) and the vibration acceleration peak (VAP) in both time and frequency domains. The experimental and numerical results demonstrate that the open trench has clear effects on the dynamic soil response. Both time and frequency domain results suggest that the dynamic response of the soils beyond the open trenches could be significantly affected, due to the existence of the open trench. According to the frequency domain analysis, the inclusion of open trenches could effectively reduce the soil response in a higher frequency range. Due to reflection effects at the boundaries of the trench, an amplification of the soil response in front of the open trench is observed. Parametric study by means of numerical simulations is also performed. The width of the open trench demonstrates negligible effects on the dynamic soil response, whilst the trench depth exhibits a large influence on the trench isolation performance. With an increase in the trench depth, the isolation performance is significantly improved. It is concluded that the open trenches perform well as an isolation barrier, in mitigating the vibration induced by subway trains.

scholarly journals Analyses of Countermovement Jump Performance in Time and Frequency Domains

2021 ◽  
Vol 78 (1) ◽  
pp. 41-48
Author(s):  
Zhanxin Sha ◽  
Zhaoxian Zhou ◽  
Boyi Dai
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Frequency Component ◽  
Frequency Domain Analysis ◽  
American Football ◽  
Jump Height ◽  
Jump Performance ◽  
Additional Information ◽  
Frequency Domains ◽  
Time And Frequency Domains

Abstract This study aimed to analyze counter-movement jump (CMJ) performance in time and frequency domains. Fortyfour Division I American football players participated in the study. Kinetic variables were collected from both dominant and non-dominant legs using two force plates. Normalized peak power, normalized net impulse, and normalized peak force significantly correlated with jump height (r = .960, r = .998, r = .725, respectively with p < .05). The mean frequency component was significantly correlated with CMJ performance (r = .355 with p < .05). The reliability of the frequency variables was higher than the time domain variables. Frequency domain variables showed weaker correlations with jump height compared with time domain variables. Frequency domain analysis provides frequency components, which represent the rate of energy transmission from the eccentric phase to the end of the push-off phase. Frequency component information may provide additional information for the analyses of CMJ performance for athletes.

Effect of Time and Frequency Manipulation on Syllable Perception in Developmental Dyslexics

1997 ◽  
Vol 40 (4) ◽  
pp. 912-924 ◽  
Author(s):  
Ken I. McAnally ◽  
Peter C. Hansen ◽  
Piers L. Cornelissen ◽  
John F. Stein
Keyword(s):  
Frequency Domain ◽  
Time Domain ◽  
Developmental Dyslexia ◽  
Stop Consonant ◽  
Stop Consonants ◽  
Systematic Improvement ◽  
Frequency Domains ◽  
The Time Domain ◽  
Time And Frequency Domains

Many people with developmental dyslexia have difficulty perceiving stop consonant contrasts as effectively as other people and it has been suggested that this may be due to perceptual limitations of a temporal nature. Accordingly, we predicted that perception of such stimuli by listeners with dyslexia might be improved by stretching them in time—equivalent to speaking slowly. Conversely, their perception of the same stimuli ought to be made even worse by compressing them in time—equivalent to speaking quickly. We tested 15 children with dyslexia on their ability to identify correctly consonant-vowel-consonant (CVC) stimuli that had been stretched or compressed in the time domain. We also tested their perception of the same CVC stimuli after the formant transitions had been stretched or compressed in the frequency domain. Contrary to our predictions, we failed to find any systematic improvement in their performance with either manipulation. We conclude that simple manipulations in the time and frequency domains are unlikely to benefit the ability of people with dyslexia to discriminate between CVCs containing stop consonants.

Dynamic Performance of Shoe Centerless Grinding

2002 ◽  
Author(s):  
Hong Zhang ◽  
Junghsen Lieh ◽  
David Yen
Keyword(s):  
Numerical Simulations ◽  
Dynamic Performance ◽  
Critical Parameters ◽  
Grinding Process ◽  
Mass System ◽  
Frequency Domains ◽  
Single Mass ◽  
Centerless Grinding ◽  
The Stability ◽  
Time And Frequency Domains

In this paper, the dynamic performance of shoe centerless grinding is presented. The model is a single-mass system in time and frequency domains. Based on the model, the stability and the critical parameters of the grinding process were studied. Numerical simulations were conducted in order to evaluate key parameters for the grinding process. The model was verified by experiments from real grinding trials.

Study on the vibration isolation performance of an open trench–wave impedance block barrier using perfectly matched layer boundaries

2020 ◽  
pp. 107754632097696
Author(s):  
Fengxi Zhou ◽  
Zhixiong Zhou ◽  
Qiang Ma
Keyword(s):  
Frequency Domain ◽  
Vibration Isolation ◽  
Ground Vibration ◽  
Perfectly Matched Layer ◽  
Wave Impedance ◽  
Vibration Source ◽  
Absorbing Boundary ◽  
Open Trench ◽  
Vibration Isolation Performance ◽  
Isolation Performance

One of the problems associated with vibration pollution is ground vibration. In view of the isolation of objects protected from ground-transmitted vibrations, a novel type of vibration isolation barrier, an open trench–wave impedance block, is proposed. Based on the perfectly matched layer absorbing boundary, the two-dimensional finite element method in the frequency domain is used to investigate the vibration isolation performance of the open trench–wave impedance block barrier system for reducing the vibration generated by a vibration source. Firstly, the governing equation of the perfectly matched layer absorbing boundary is established in the frequency domain by using complex coordinate stretching. Secondly, using Galerkin approximation technology, the calculation formula of the second-order non-splitting perfectly matched layer with the displacement as the basic unknown quantity is given for the finite element method in the frequency domain. Finally, the influence of the physical parameters (modulus ratio between ground and wave impedance block), geometric parameters (dimension and layout of an open trench–wave impedance block barrier, including embedded length and width) and the load parameters (exciting frequency of the vibration source) on its vibration isolation performance is researched. The results show that the open trench–wave impedance block barrier system can provide a more flexible and efficient isolation barrier for ground vibration control.

A Design of Comfortable Dental Treatment Sound Based on Chord-forming in Time and Frequency Domains

2015 ◽  
Vol 135 (12) ◽  
pp. 1565-1573
Author(s):  
Yoshitaka Ohshio ◽  
Daisuke Ikefuji ◽  
Yuko Suhara ◽  
Masato Nakayama ◽  
Takanobu Nishiura
Keyword(s):  
Dental Treatment ◽  
Frequency Domains ◽  
Time And Frequency Domains

Fuzzy Extreme Analysis in Time- and Frequency Domains

2011 ◽  
Vol 57 (4) ◽  
Author(s):  
Włodzimierz Pogribny ◽  
Marcin Drzycimski ◽  
Zdzisław Drzycimski
Keyword(s):  
Frequency Domains ◽  
Time And Frequency Domains

scholarly journals A phase-locked loop using ESO-based loop filter for grid-connected converter: performance analysis

2021 ◽  
Author(s):  
Baoling Guo ◽  
Seddik Bacha ◽  
Mazen Alamir ◽  
Julien Pouget
Keyword(s):  
Performance Analysis ◽  
Frequency Domain ◽  
Low Frequency ◽  
Experimental Tests ◽  
Frequency Measurement ◽  
Phase Locked Loop ◽  
Frequency Domain Analysis ◽  
Loop Filter ◽  
Control Stability ◽  
Unbalanced Grid

AbstractAn extended state observer (ESO)-based loop filter is designed for the phase-locked loop (PLL) involved in a disturbed grid-connected converter (GcC). This ESO-based design enhances the performances and robustness of the PLL, and, therefore, improves control performances of the disturbed GcCs. Besides, the ESO-based LF can be applied to PLLs with extra filters for abnormal grid conditions. The unbalanced grid is particularly taken into account for the performance analysis. A tuning approach based on the well-designed PI controller is discussed, which results in a fair comparison with conventional PI-type PLLs. The frequency domain properties are quantitatively analysed with respect to the control stability and the noises rejection. The frequency domain analysis and simulation results suggest that the performances of the generated ESO-based controllers are comparable to those of the PI control at low frequency, while have better ability to attenuate high-frequency measurement noises. The phase margin decreases slightly, but remains acceptable. Finally, experimental tests are conducted with a hybrid power hardware-in-the-loop benchmark, in which balanced/unbalanced cases are both explored. The obtained results prove the effectiveness of ESO-based PLLs when applied to the disturbed GcC.

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