Papers by Keyword: Fast Fourier Transform (FFT)

Abstract: Effective condition monitoring is crucial for maintaining industrial rotating machinery. This study investigates a predictive maintenance approach to diagnose and resolve excessive vibration in a refinery’s centrifugal pump. Vibration analysis using Fast Fourier Transform (FFT) and phase difference diagnostics identified a dynamic imbalance caused by contaminant accumulation on the impeller, resulting in vibration spikes of 11.61 mm/s with a dominant FFT spectrum at 1X RPM. To mitigate this issue, dynamic balancing was performed in accordance with ISO 1925 and ISO 1940-1 standards, successfully reducing the vibration to 3.59 mm/s. The results validate vibration-based diagnostics as a proactive maintenance tool, minimizing downtime and improving reliability. This study demonstrates how predictive maintenance strategies can enhance the performance of rotating machinery, with potential applications in other industrial systems.

Abstract: New techniques for the analysis of complex images were advanced by the example of asurface microrelief of the Fe70Cr15B15 alloys, obtained by the melt-spinning at different linearvelocity of a quenching roller. Proposed techniques are based on the fast Fourier transform of theimage using digital signal processors. The degree of morphological ordering/disordering of ribbonswas determined due to the parameterization of mode spectra by entropy functionals. The best glassforming ability for alloys of the studied composition was obtained at 30 m/s.

Abstract: The three phase induction motor is a popularly used machine in many of the industries, which is well known for its robustness, reliability, cost effectiveness, efficient and safe operation. The unnoticed manufacturing failure, mistakes during repair work, exceeding life time may be some of the causes of the induction motor failure, which may lead to the unknown shut down time of the industry. The condition monitoring plays important role as it has the influence on the production of materials and profit. In our work, the induction motor is modelled using stationary reference frame and analysed for single phasing stator fault. The techniques used in detecting the single phasing (open circuit) failures are Park’s vector approach and Fast Fourier Transform (FFT). Park’s vector approach is used for detecting the faults occurring at various phases and FFT is used for detecting the faults of the induction motor working under no load and varying loading conditions.

Abstract: on the basis of discussing virtues and defects of traditional ocean wave spectrum modeling method, this paper proposes a new method for accurate real-time ocean wave simulation. It builds the basic ocean wave model based on improved Gerstner wave. To resolve contradiction between accuracy and real time, it deduces discrete FFT algorithm model of ocean wave, and acquires parameters needed in ocean wave FFT model by sampling wave vector spectrum. The result of simulation proves this method is feasible and effective.

Abstract: The inter-harmonic spectrum of an electrical voltage or current from discrete Fourier transform can not only be caused by genuine inter-harmonic components, but can also be caused by other system disturbances. Therefore, the existence determination of genuine inter-harmonic s from the spectrum becomes the premise for further calculation of inter-harmonic parameters. From the theoretical perspective, this paper firstly analyzes and points out that the waveform difference among each cycle in the analysis window is the cause of the existence of inter-harmonic spectrum, and then presents a method to determine the existence of genuine inter-harmonic components, which is based on inter-harmonic time-frequency contour chart and the component appearance rate. The presented method firstly performs continuous discrete Fourier transform on the captured signal with certain duration and obtains the corresponding absolute time-frequency matrix, and then the genuine inter-harmonics can be distinguished based on the component appearance rate of the matrix and the criterion threshold. The method is easy to implement with clear principle, it can distinguish the genuine inter-harmonic s from the measured signal. The analysis on several data groups from real measurements verifies the effectiveness and the practicability of the method.

Abstract: The research studies the characteristics of the vertical flow past a finite-length horizontal cylinder at low Reynolds numbers (Re_D) from 250 to 1080. The experiments were performed in a vertical closed-loop water tunnel. Flow fields were observed by the particle tracer approach for flow visualization and measured by the Particle Image Velocimetry (P.I.V.) approach for velocity fields. The characteristics of vortex formation in the wake of the finite-length cylinder change at different regions from the tip to the base of it. Near the tip, a pair of vortices in the wake was observed and the size of the vortex increased as the observed section was away from the tip. Around a distance of 3 diameters of the cylinder from its tip, the vortex street in the wake was observed. The characteristics of vortex formation also change with increasing Reynolds numbers. At X/D = -3, a pair of vortices was observed in the wake for Re_D = 250, but as the Re_D increases the vortex street was observed at the same section. The vortex shedding frequency is analyzed by Fast Fourier Transform (FFT). Experimental results show that the downwash flow affects the vortex shedding frequency even to 5 diameters of the cylinder from its tip. The interaction between the downwash flow and the Von Kármán vortex street in the wake of the cylinder is presented in this paper.

Abstract: In allusion to the problem of launching precision, it carried on the research of the effect of shipborne missile launch position based on the spectrum analysis technology. A rigid-flexible coupling integrative model of ship movement and missile launch was built by use of virtual prototype technology. Simulation analyses on a variety of conditions were automatic conducted by launch time parameterized scripting language, and missile muzzle attitude parameters of different launch position were gained. By using of spectrum analysis which is based on FFT, the missile dynamic responsive was analyzed, and the relationship between launch position and accuracy was established. Then the position of the weapon system can be designed according to the specific motion characteristics of ship. The research result is also constructive to the selecting of suitable launch position.

Abstract: Using the MCU STC12C5A60S2 as the main control unit, in which the internal integration of 10 8 road A/D converter, which has high data processing speed, rich resources, can meet the requirements of general control. The development process is as follows: first to initialize A/DC, A/DC interrupt occurs for signal acquisition and the interrupt service subroutine, data stored in the specified array. The data after the acquisition, called FFT (Fast Fourier transform) spectral transform and analysis functions, and stored in corresponding array, through the LED display the collected data are displayed.

Abstract: How to improve the frequency resolution, especially in the low frequency bands, is an important problem for many applications. A novel approach based on sparse representation was proposed for this problem. In this work, we first discussed the design of the over-completed dictionary with the high frequency resolution, and then Matching Pursuit was advised to perform sparse decomposition using Matching Pursuit Tool Kit. Next, the frequency information was extracted from the code book of the results of Matching Pursuit. Finally, the experiments demonstrated the improvement of the frequency resolution for the proposed approach.

Abstract: With wider deployments of smart meters, smart grids, and distributed generation, power quality monitoring has become increasingly important. It is well known that fast Fourier transform (FFT) is a powerful tools for power signal harmonic analysis, but leakage effect, picket fence effect, and aliasing effect make FFT suffer from specific restrictions. In this paper, we proposed a new method for power signal harmonic analysis. The major components of this method are a frequency and phasor estimating algorithm, a real time procedure and an adaptive monitoring. To verify this method, we provided the comparisons of this method with FFT.