In-Plane Displacement Component Measurement Using Fourier Transform Filtering Technique

2021 ◽  
pp. 575-578
Author(s):  
Abhijit Ghosh ◽  
Rohit Kumar ◽  
Nishant Kumar ◽  
A. K. Nirala
Keyword(s):  
Fourier Transform ◽  
Displacement Component ◽  
Filtering Technique ◽  
Plane Displacement

scholarly journals Frequency adaptive sliding fourier transform for synchronizing VSI to the grid

2019 ◽  
Vol 10 (2) ◽  
pp. 1034 ◽  
Author(s):  
Osama M. Arafa ◽  
M. E. Abdallah ◽  
Ghada A. Abdel Aziz
Keyword(s):  
Fourier Transform ◽  
Phase Angle ◽  
Phase Detector ◽  
Spectral Leakage ◽  
Double Frequency ◽  
Harmonic Rejection ◽  
Three Phase ◽  
Stationary Reference Frame ◽  
Filtering Technique ◽  
Phase Setting

Sliding Discrete Fourier Transform (SDFT) is very efficient regarding computational load and it possesses a very fast phase angle detection with excellent harmonic rejection at nominal frequency. However, at off-nominal frequency, SDFT generates errors in both magnitude and phase angle due to spectral leakage. This paper introduces a workaround for Fourier Transform to handle this disability under off-nominal frequency while avoiding variable-rate sampling. Sliding Fourier Transform (SFT) is used as a phase detector for a phase-locked loop whose output frequency is used to drive the SFT. The paper revisits the mathematics of Fourier Transform (FT) in a three-phase setting via a time-domain approach to show a newly proposed filtering technique for the double-frequency oscillation just by summing the FT sine/cosine filter outputs of the three individual phases. Also, the analysis aims to determine and correct the phase and magnitude errors under offnominal frequency operation. The proposed technique (SFT-PLL) is tested in real time on dSPACE DS1202 DSP using voltage vectors that are pregenerated to simulate the most adverse grid conditions. The testing scenarios compare the performance of the SFT-PLL with that of the Decoupled Stationary Reference Frame PLL (dαβPLL). The results prove that SFT-PLL is superior to dαβPLL.

scholarly journals Evaluation of Clipping and Filtering-Based PAPR Reduction in OFDM System

2017 ◽  
Vol 1 (2) ◽  
pp. 18
Author(s):  
N. M. A. E. D. Wirastuti ◽  
N. Pramaita ◽  
I M. A. Suyadnya ◽  
D. C. Khrisne
Keyword(s):  
Fourier Transform ◽  
Orthogonal Frequency Division Multiplexing ◽  
High Speed ◽  
Average Power ◽  
Ofdm Systems ◽  
Ofdm System ◽  
Parallel Data ◽  
Serial Data ◽  
Filtering Technique ◽  
Clipping And Filtering

This paper investigates clipping and filtering techniques in reducing peak average power ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) system. The concept of OFDM is to split a high speed serial data into parallel data at a lower speed, then the parallel data carried by mutually orthogonal subcarriers. The high of PAPR is one of disadvantages of OFDM system. The high PAPR can damages the form of OFDM and reduces its performance. The purpose of this study is to reduce PAPR using simulation. OFDM was simulated with and without clipping filtering then compared.  The methods used to reduce PAPR was clipping and filtering technique. Clipping and filtering technique operates by clipping the output of inverse Fourier transform that exceed the threshold. Graphics PAPR vs. CCDF was used to evaluate the performance of OFDM systems. PAPR for OFDM system using Fourier transform when CCDF = 10-3 is 11,2 dB, with classical clipping PAPR was 4,1 dB and PAPR 4,6 dB when with deep clipping.

scholarly journals Damage accumulation near the cold-expanded hole due to high-cycle fatigue by crack compliance method

2021 ◽  
Vol 16 (59) ◽  
pp. 115-128
Author(s):  
Sviatoslav Eleonsky ◽  
Yuri Matvienko ◽  
Vladimir Pisarev ◽  
Michael Zajtsev
Keyword(s):  
Residual Stress ◽  
Fracture Mechanics ◽  
Damage Accumulation ◽  
High Cycle Fatigue ◽  
Initial Point ◽  
Displacement Component ◽  
Electronic Speckle Pattern Interferometry ◽  
Cycle Fatigue ◽  
Fatigue Damage Accumulation ◽  
Plane Displacement

The novel destructive method is implemented for quantitative assessment of fatigue damage accumulation in the stress concentration zone accompanied by residual stress due to cold expansion of the through-thickness hole. Damage accumulation is reached by preliminary cyclic loading of plane specimens with cold-expanded holes. Narrow notches, emanating from the hole edge at different stages of high-cycle fatigue, serve to manifest a damage level. These notches are inserted without applying external load. Deformation response to local material removing, caused by pure residual stress influence, is measured by electronic speckle pattern interferometry (ESPI) in terms of in-plane displacement components. Normalized values of the notch mouth open displacement (NMOD), in-plane displacement component at the initial point of the notch acting in the notch direction (U0), in-plane displacement component at the final point of the notch acting in the notch direction (U1) and the stress intensity factor (SIF) are used as current damage indicators. Numerical integration of curves, describing an evolution of each fracture mechanics parameter over lifetime, produces the damage accumulation function in an explicit form. It is established that all four fracture mechanics parameters give very close results.

scholarly journals Fourier-Transform-Based Surface Measurement and Reconstruction of Human Face Using the Projection of Monochromatic Structured Light

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2529
Author(s):  
Bingquan Chen ◽  
Hongsheng Li ◽  
Jun Yue ◽  
Peng Shi
Keyword(s):  
Fourier Transform ◽  
Structured Light ◽  
Surface Measurement ◽  
Human Face ◽  
Image Processing Algorithm ◽  
Optical Filtering ◽  
Linearly Polarized ◽  
Potential Applications ◽  
Filtering Technique ◽  
The Fourier Transform

This work presents a new approach of surface measurement of human face via the combination of the projection of monochromatic structured light, the optical filtering technique, the polarization technique and the Fourier-transform-based image-processing algorithm. The theoretical analyses and experimental results carried out in this study showed that the monochromatic feature of projected fringe pattern generated using our designed laser-beam-based optical system ensures the use of optical filtering technique for removing the effect of background illumination; the linearly-polarized characteristic makes it possible to employ a polarizer for eliminating the noised signal contributed by multiply-scattered photons; and the high-contrast sinusoidal fringes of the projected structured light provide the condition for accurate reconstruction using one-shot measurement based on Fourier transform profilometry. The proposed method with the portable and stable optical setup may have potential applications of indoor medical scan of human face and outdoor facial recognition without strict requirements of a dark environment and a stable object being observed.

scholarly journals Residual stresses near cold-expanded hole at different stages of high-cycle fatigue by crack compliance data

2021 ◽  
Vol 15 (56) ◽  
pp. 171-196
Author(s):  
Sviatoslav Eleonsky ◽  
Vladimir Pisarev ◽  
Mikhail Zajtsev ◽  
Mikhail Zichenkov ◽  
Marat Abdullin
Keyword(s):  
Residual Stress ◽  
High Cycle Fatigue ◽  
Low Cycle Fatigue ◽  
Speckle Pattern ◽  
Displacement Component ◽  
Electronic Speckle Pattern Interferometry ◽  
Cycle Fatigue ◽  
Residual Stress Field ◽  
Exit Surface ◽  
Plane Displacement

Experimental method for a characterization of high-cycle fatigue evolution of residual stress near cold-expanded hole is developed and implemented. The technique is based on simultaneous measurements of deformation response to narrow notch, inserted in residual stress field, on opposite specimen’s faces by electronic speckle-pattern interferometry (ESPI). Two-side measurements of notch opening displacements are performed when a single notch, emanating from cold-expanded hole edge, is inserted. The transition from in-plane displacement component to residual stress intensity factor (SIF) values follows from the relationships of modified version of the crack compliance method. The approach provides a difference in residual stress values referred to mandrel entrance and exit surface. Notches are inserted at different stages of low-cycle fatigue without applying external load. The results obtained describe fine nuances of residual stress evolution, which cannot be considered as monotonic relaxation.

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