Fourier Descriptors for Improved Analysis of Distortion Transfer and Generation

2017 ◽  
Author(s):  
Marshall W. Peterson ◽  
Steven E. Gorrell ◽  
Michael G. List
Keyword(s):  
Phase Shift ◽  
Fourier Analysis ◽  
Phase Change ◽  
Fourier Descriptors ◽  
Total Amplitude ◽  
Flow Physics ◽  
Profile Shape ◽  
Compressor Design ◽  
Modal Amplitude ◽  
Low Distortion

For fan/compressor design, quantifying distortion transfer and generation bladerow by bladerow through a fan/compressor is important to understand the flow physics and predict performance. What is needed are descriptors capable of describing distortion profiles with both high and low distortion content and account for the reshaping of distortion profiles. Four key parameters were identified as desirable to quantitatively capture distortion transfer, generation and effects on performance: distortion magnitude, shape, severity and phase. A set of distortion descriptors based on Fourier analysis are shown to quantitatively capture distortion magnitude, shape and phase change across bladerows. These Fourier descriptors are modal amplitude, total amplitude, and phase shift. When used together, these Fourier descriptors can be used to qualitatively describe any conceivable profile shape for any parameter.

Measuring technique of a phase shift based on Fourier analysis of differential interferograms

2015 ◽  
Vol 118 (6) ◽  
pp. 971-977 ◽  
Author(s):  
G. N. Vishnyakov ◽  
G. G. Levin ◽  
V. L. Minaev
Keyword(s):  
Phase Shift ◽  
Fourier Analysis ◽  
Measuring Technique

Phase Shift Measurement of a Retarder Based on Fourier Analysis

2008 ◽  
Vol 28 (1) ◽  
pp. 105-109
Author(s):  
赵廷生 Zhao Tingsheng ◽  
李国华 Li Guohua ◽  
彭捍东 Penh Handong ◽  
周文平 Zhou Wenping
Keyword(s):  
Phase Shift ◽  
Fourier Analysis ◽  
Shift Measurement

scholarly journals Buoyancy Driven Turbulent Heat Transfer Characteristics in Enclosure Filled with Phase Change Materials

2020 ◽  
Vol 9 (1) ◽  
pp. 717-721
Keyword(s):  
Heat Source ◽  
Phase Change ◽  
Phase Change Materials ◽  
Transient Flow ◽  
Turbulent Heat Transfer ◽  
Convection Flow ◽  
Turbulent Heat ◽  
Navier Stokes Equation ◽  
Flow Physics ◽  
Turbulent Characteristics

The exponentially growing computing capabilities of electronic circuits require effective and efficient heat sink designs to control the temperature inside the system. To achieve the desired temperature for efficient working of electronic devices, phase change materials are widely used. In the present study we discuss the complex flow physics of a phase change material filled in a cubical enclosure in the turbulent flow regime with a local heater mounted on the enclosure bottom wall. The thermal properties of local heat source are that of silicon at a working temperature of 330 K. The walls of the enclosure other than the heat source are considered as adiabatic. The turbulent natural convection flow is modeled by the computational fluid dynamics (CFD) approach using Reynolds averaged Navier-stokes equation (RANS) with Lambremhorst k-ε turbulence model. A finite difference method is used to discretize the governing equations and an in-house CFD code is developed for simulating the turbulent characteristics. The flow physics of three different phase change materials (n-Octadecane, PEG900, Paraffin (RT60)) has been analyzed with Groshof number being fixed for all three phase change materials. The transient flow characteristics are investigated by plotting the stream function, velocity and temperature contours of the phase change materials..

A low-current and low-distortion wideband amplifier using 0.2-μm gate MODFET fabricated by using phase-shift lithography

2000 ◽  
Vol 48 (5) ◽  
pp. 771-776 ◽  
Author(s):  
H. Ishida ◽  
K. Miyatsuji ◽  
T. Tanaka ◽  
H. Takenaka ◽  
H. Furukawa ◽  
...  
Keyword(s):  
Phase Shift ◽  
Wideband Amplifier ◽  
Low Distortion

The LDE-Type Flare Occurrence (1969-1993)

1994 ◽  
Vol 144 ◽  
pp. 279-282
Author(s):  
A. Antalová
Keyword(s):  
Time Series ◽  
Fourier Analysis ◽  
Sunspot Cycle ◽  
List Type ◽  
Type Number ◽  
Solar Cycles ◽  
Type Iv ◽  
Long Duration ◽  
Cycle Maximum ◽  
Flare Index

AbstractThe occurrence of LDE-type flares in the last three cycles has been investigated. The Fourier analysis spectrum was calculated for the time series of the LDE-type flare occurrence during the 20-th, the 21-st and the rising part of the 22-nd cycle. LDE-type flares (Long Duration Events in SXR) are associated with the interplanetary protons (SEP and STIP as well), energized coronal archs and radio type IV emission. Generally, in all the cycles considered, LDE-type flares mainly originated during a 6-year interval of the respective cycle (2 years before and 4 years after the sunspot cycle maximum). The following significant periodicities were found:• in the 20-th cycle: 1.4, 2.1, 2.9, 4.0, 10.7 and 54.2 of month,• in the 21-st cycle: 1.2, 1.6, 2.8, 4.9, 7.8 and 44.5 of month,• in the 22-nd cycle, till March 1992: 1.4, 1.8, 2.4, 7.2, 8.7, 11.8 and 29.1 of month,• in all interval (1969-1992):a)the longer periodicities: 232.1, 121.1 (the dominant at 10.1 of year), 80.7, 61.9 and 25.6 of month,b)the shorter periodicities: 4.7, 5.0, 6.8, 7.9, 9.1, 15.8 and 20.4 of month.Fourier analysis of the LDE-type flare index (FI) yields significant peaks at 2.3 - 2.9 months and 4.2 - 4.9 months. These short periodicities correspond remarkably in the all three last solar cycles. The larger periodicities are different in respective cycles.

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