Phase shifting, spatial Fourier transform, and fringe tracking analysis of hypersonic flow field holographic interferograms

1993 ◽  
Author(s):  
Chris K. Karaguleff ◽  
Ronald A. Parker ◽  
James E. Craig
Keyword(s):  
Fourier Transform ◽  
Flow Field ◽  
Hypersonic Flow ◽  
Phase Shifting ◽  
Fringe Tracking

Multi-STFT for adaptive SCPS phase determination

2009 ◽  
Vol 17 (4) ◽  
Author(s):  
R. Sitnik
Keyword(s):  
Fourier Transform ◽  
Carrier Phase ◽  
Fringe Pattern ◽  
Phase Shifting ◽  
Shape Measurement ◽  
Step Method ◽  
Phase Determination ◽  
3D Shape Measurement ◽  
Phase Calculation ◽  
Carrier Phase Shifting

AbstractThis paper presents a fast and reliable approach for phase modulo 2π-calculation from a single fringe pattern. It calculates correct phase values even for very complex and variable shape gradients based on a locally variable fringe period determined for the entire image. In the paper, a new two-step method for wrapped phase calculation is proposed. It is performed through the use of a method based on a multiple local fast Fourier transform for estimation of a local fringes period map and a 5-point spatial carrier phase shifting (SCPS) formula for phase modulo 2π-calculation. The described approach is verified by a correct demodulation of a real fringe pattern taken by a 3D-shape measurement system.

Reduction of Selected Metal Oxides in a Thermal Plasma Produced by a Nontransferred ARC Torch

1987 ◽  
Vol 98 ◽  
Author(s):  
Brent A. Detering ◽  
James A. Batdorf ◽  
Chien M. Wai
Keyword(s):  
Thermal Decomposition ◽  
Fourier Transform ◽  
Flow Field ◽  
Emission Spectroscopy ◽  
Plasma Plume ◽  
Particle Morphology ◽  
Arc Plasma ◽  
Plasma Arc ◽  
Transform Method ◽  
Oxide Particles

ABSTRACTPlasma flow field temperatures are determined in a nontransferred arc plasma using emission spectroscopy. This technique is then utilized to identify thermal decomposition and reduction products produced in the plasma plume when metal oxide particles are injected into the plasma arc. The processed particles are then studied using AAS, SEM, EDS and XRD to characterize the chemical changes that have occurred in the particles. A Fourier transform method is used to study changes in particle morphology.

Generalized Phase-Shifting Phase Retrieval Approach Based on Time-Domain Fourier Transform

2015 ◽  
Vol 42 (9) ◽  
pp. 0908004
Author(s):  
张望平 Zhang Wangping ◽  
吕晓旭 Lü Xiaoxu ◽  
刘胜德 Liu Shengde ◽  
赵晖 Zhao Hui ◽  
钟丽云 Zhong Liyun
Keyword(s):  
Fourier Transform ◽  
Time Domain ◽  
Phase Retrieval ◽  
Phase Shifting

A uniformly valid solution for the hypersonic flow past blunted bodies

1968 ◽  
Vol 31 (2) ◽  
pp. 397-415 ◽  
Author(s):  
W. Schneider
Keyword(s):  
Flow Field ◽  
Hypersonic Flow ◽  
Local Thermodynamic Equilibrium ◽  
Density Ratio ◽  
Intersection Point ◽  
The Body ◽  
Boundary Values ◽  
Stagnation Region ◽  
Flow Past ◽  
Valid Solution

The plane and axisymmetric hypersonic flow past blunted bodies is investigated as an inverse problem (shock shape given). The fluid may behave as a real gas in local thermodynamic equilibrium. Viscosity and heat conduction are neglected. An analytical solution uniformly valid in the whole flow field (from the stagnation region up to large distances from the body nose) is given. The solution is based on two main assumptions: (i) the density ratio ε across the shock is very small, (ii) the pressure at a pointPof the disturbed flow field isnotvery small compared with the pressure immediately behind the shock in the intersection point of the shock surface with its normal throughP.TermsO(ε) are neglected in comparison with 1, but it is not necessary for the shock layer to be thin. The change of velocity along streamlines is taken into account. In order to calculate the flow quantities one has to evaluate only two integrals (equations (49) and (53) together with the boundary values (5) and (10)). The application of the solution is illustrated and the accuracy is tested in some examples.

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