scholarly journals An idea for roughly estimating tonal audibility by FFT analysis

2022 ◽  
Vol 43 (1) ◽  
pp. 69-72
Author(s):  
Tomohiro Kobayashi ◽  
Sakae Yokoyama
Keyword(s):  
Fft Analysis

Dectection of early thrombus formation in LVAD by accoustic fast fourier transformation (FFT) analysis. A novel approach for monitoring

2014 ◽  
Vol 62 (S 01) ◽  
Author(s):  
P. von Samson-Himmelstjerna ◽  
A. Meyer ◽  
T. Müller ◽  
N. Zießnitz ◽  
J. Garbade ◽  
...  
Keyword(s):  
Fourier Transformation ◽  
Thrombus Formation ◽  
Fast Fourier Transformation ◽  
Novel Approach ◽  
Fft Analysis

METHODOLOGY OF OBJECTIVE EVALUATION OF THE QUALITY BEARINGS BY VIBRO-ACOUSTICS AND ITS COMPARISON WITH A SUBJECTIVE METHOD

Akustika ◽  
2020 ◽  
pp. 58-66
Author(s):  
Stanislav Žiaran ◽  
Ondrej Chlebo ◽  
Ĺubomír Šooš
Keyword(s):  
Dynamic Load ◽  
Subjective Evaluation ◽  
Objective Evaluation ◽  
Living Environment ◽  
Working Environment ◽  
Subjective Method ◽  
Auditory Organ ◽  
Objective Methodology ◽  
Fft Analysis

The quality of bearing production has an impact not only on their reliability and lifetime, but also on the dynamic load of the working and living environment by excessive vibration and thus also noise. The intensity of the noise emitted by a bearing which is perceived by man characterizes the quality of its production. Reducing the dynamic load of mechanical systems and their components is reflected in the working environment by reducing noise emissions and immissions. The article proposes an objective method of bearing quality assessment based on measuring vibro-acoustic parameters of dynamic load of a new bearing using FFT analysis and the magnitude of the amplitude of bearing vibration acceleration and compares it with a subjective method that also uses the human auditory organ to assess bearing quality. The results of vibro-acoustic measurements were analysed in terms of vibration intensity and the noise of the produced bearings. The proposed objective methodology was compared with the subjective evaluation of the quality of bearings and the results of this methodology matched. The proposed methodology is applicable to all types of bearings, and it is possible to automate this methodology in the production process.

scholarly journals Implications of Self-Potential Distribution for Groundwater Flow System in a Nonvolcanic Mountain Slope

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Tada-nori Goto ◽  
Kazuya Kondo ◽  
Rina Ito ◽  
Keisuke Esaki ◽  
Yasuo Oouchi ◽  
...  
Keyword(s):  
Groundwater Flow ◽  
General Trend ◽  
Flow System ◽  
Ground Surface ◽  
Mountain Slope ◽  
Infiltration Process ◽  
Groundwater Flow System ◽  
Self Potential ◽  
Sp Anomaly ◽  
Fft Analysis

Self-potential (SP) measurements were conducted at Mt. Tsukuba, Japan, which is a nonvolcanic mountain, to infer groundwater flow system in the mountain. Survey routes were set around the northern slope, and the reliability of observed SP anomaly was checked by using SP values along parallel survey routes; the error was almost within 10 mV. The FFT analysis of the spatial SP distribution allows us a separation of raw data into two components with shorter and longer wavelength. In the shorter (altitudinal) wavelength than ∼200 meters, several positive SP peaks of more than 100 mV in magnitude are present, which indicate shallow perched water discharges along the slope. In the regional SP pattern of longer wavelength, there are two major perturbations from the general trend reflecting the topographic effect. By comparing the SP and hydrological data, the perturbation around the foothill is interpreted to be caused by heterogeneous infiltration at the ground surface. The perturbation around the summit is also interpreted to be caused by heterogeneous infiltration process, based on a simplified numerical modeling of SP. As a result, the SP pattern is well explained by groundwater flow and infiltration processes. Thus, SP data is thought to be very useful for understanding of groundwater flow system on a mountain scale.

Interference fiber ring perimeter with FFT analysis

2011 ◽  
Author(s):  
Vladimir Vasinek ◽  
Jan Vitasek ◽  
Stanislav Hejduk ◽  
Jiri Bocheza ◽  
Jan Latal ◽  
...  
Keyword(s):  
Fiber Ring ◽  
Fft Analysis

FFT Analysis Using LabView as a Part of Vibration and Preventive Maintenance Class for Senior Level MET students

2005 ◽  
Author(s):  
Aniruddha Mitra ◽  
Sahana Sen
Keyword(s):  
Preventive Maintenance ◽  
Laboratory Experiments ◽  
Vibration Signal ◽  
Engineering Technology ◽  
Technology Program ◽  
Student Activities ◽  
Labview Software ◽  
Vibration Data ◽  
Set Up ◽  
Fft Analysis

An existing senior level elective course on vibration in Mechanical Engineering Technology program at Georgia Southern University has been modified significantly. Two major components have been added to this course. Those are theoretical topics on preventive maintenance and laboratory experiments. As a part of laboratory experiments, Fast Fourier Transform (FFT) was introduced as a possible tool for vibration analysis for the purposes of machine diagnosis. Utilizing the current laboratory set up for the data acquisition systems, LabView software has been used for FFT analysis of signals from various sources. Four different modules were developed and implemented. The modules are as follows: random variation in acceleration of a toy cart due to roughness of the track and pulley, regular uniform wave signal which is generated by the lateral vibration of a cantilever beam at its natural frequency, signal generated by the imported raw data from other sources (e.g. MATLAB) and vibration signal of a shaft mounted on ball bearings in order to detect the defects in the bearing. Each of these modules is illustrated in this paper with suitable examples and suggested student activities and involvements. The results from FFT analysis have been cross checked using other methods and observations. As a follow up, students have been taken to a local industry where significant amount of emphasis is given to preventive maintenance of machineries by vibration data analysis using FFT. Future possible projects include the analysis of vibration data gathered from actual machine shop. This project opens the scope for greater collaborative effort between local industries and classroom activities.

scholarly journals Decoupling of ground level pressures observed in Italian volcanoes: are they driven by space weather geo-effectiveness?

2014 ◽  
Vol 57 (3) ◽  
Author(s):  
Paolo Madonia ◽  
Paolo Romano ◽  
Salvatore Inguaggiato
Keyword(s):  
Space Weather ◽  
Atmospheric Pressure ◽  
Pressure Field ◽  
Ground Level ◽  
Total Solar Irradiance ◽  
Weather Parameters ◽  
Sun Activity ◽  
Fft Analysis ◽  
Sunspot Groups

<p>Investigations on correlation drops between near-ground atmospheric pressures measured at sea level and at higher altitudes on Italian volcanoes have been carried out. We looked for perturbations of the atmospheric pressure field driven by volcanic activity, but not excluding possible external triggers for the observed anomalies. Decorrelations between atmospheric pressures measured at Stromboli Island in stations located at different altitudes (years 2002-10) have been analysed and compared with data from other volcanic (Vesuvius) and non volcanic (Mt. Soro) orographic structures. We investigated as their possible triggers volcanic, meteorological and space weather parameters, with particular attention to Total Solar Irradiance (TSI), Kp index and Forbush decreases. Pressure decorrelations seems to be driven by astronomic cycles, with maxima in summer and minima in winter. A further contribution was found, seemingly assignable to TSI anomalies, with correlation minima occurring 12 hours after these but only during phases of high Sun activity. Moreover, during the same phases a main periodicity of about 27 days in pressure decorrelations was revealed by FFT analysis. This period is the same of the Sun Carrington rotation, expressing the periodic reappearance of sunspot groups on Sun’s surface. The strong similarity between recurrences of sunspot number and atmospheric pressure anomalies further supports the role of the former as a possible trigger for the latter.</p>

Model of Noise Source for HF Interference Calculation in a Converter Station

2007 ◽  
Vol 8 (6) ◽  
Author(s):  
Quanrui Hao ◽  
Zheng Xu
Keyword(s):  
Empirical Model ◽  
Noise Source ◽  
Equivalent Model ◽  
Basic Principles ◽  
Operating Modes ◽  
Snubber Circuit ◽  
Power Line Carrier ◽  
Actual Spectrum ◽  
Physical Quantities ◽  
Fft Analysis

For high-frequency (HF) interference in an HVDC converter station, the modeling of the noise source which causes interference with the power line carrier (PLC) remains a problem. Based on the profound analysis of the basic principles on which HF noise in PLC band is produced during the commutation process, the equivalent model of the HVDC valve with a snubber circuit is applied to the simulation of the GUI-GUANG HVDC project in PSCAD/EMTDC. Then spectrum plots of the noise source in the frequency domain are obtained by FFT analysis of the voltage waveforms gained from the simulation. Through analyzing the spectrum characteristics of the noise source in various operating modes, the main factors influencing the level of HF noise are found. Furthermore, a modified empirical model used to calculate the level of the noise source is introduced, with particular explanation of the physical quantities used in the model. The spectra of the noise source gained from the modified empirical model and from the simulation are compared with an actual spectrum based on the GUI-GUANG HVDC project. The results show that the modified empirical model can meet the requirement of HF interference calculation.

scholarly journals Endocardial activation during ventricular fibrillation in normal and failing canine hearts

2000 ◽  
Vol 279 (4) ◽  
pp. H1737-H1747 ◽  
Author(s):  
Gordon L. Pierpont ◽  
Sumeet S. Chugh ◽  
John A. Hauck ◽  
Charles C. Gornick
Keyword(s):  
Ventricular Fibrillation ◽  
Balloon Catheter ◽  
Three Dimensional ◽  
Left Ventricular ◽  
Multielectrode Array ◽  
Three Dimensional Model ◽  
Centroid Frequency ◽  
Rapid Ventricular Pacing ◽  
Fft Analysis ◽  
Endocardial Activation

Because congestive heart failure (CHF) promotes ventricular fibrillation (VF), we compared VF in seven dogs with CHF induced by combined myocardial infarction and rapid ventricular pacing to VF in six normal dogs. A noncontact, multielectrode array balloon catheter provided full-surface real-time left ventricular (LV) endocardial electrograms and a dynamic color-coded display of endocardial activation projected onto a three-dimensional model of the LV. Fast Fourier transform (FFT) analysis of virtual electrograms showed no difference in peak or centroid frequency in CHF dogs compared with normals. The average number of simultaneous noncontiguous wavefronts present during VF was higher in normals (2.4 ± 1.0 at 10 s of VF) than in CHF dogs (1.3 ± 1.0, P < 0.005) and decreased in both over time. The wavefront “turnover” rate, estimated using FFT of the noncontiguous wavefront data, did not differ between normals and CHF and did not change over 5 min of VF. Thus the fundamental frequency characteristics of VF are unaltered by CHF, but dilated abnormal ventricles sustain fewer active wavefronts than do normal ventricles.

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