Autocorrelation-function method of measuring film thicknesses

1986 ◽  
Vol 29 (5) ◽  
pp. 391-393 ◽  
Author(s):  
V. K. Grigor'ev ◽  
N. N. Solov'ev ◽  
O. I. Shvedova
Keyword(s):  
Autocorrelation Function ◽  
Function Method

Acoustic Sounder Observations of Atmospheric Turbulence Parameters in a Convective Boundary Layer

1993 ◽  
Vol 32 (8) ◽  
pp. 1433-1440 ◽  
Author(s):  
Frank Quintarelli
Keyword(s):  
Boundary Layer ◽  
Atmospheric Turbulence ◽  
Autocorrelation Function ◽  
Dissipation Rate ◽  
Function Method ◽  
Convective Conditions ◽  
Convective Boundary ◽  
Pulse Volume ◽  
Spectral Variance ◽  
Turbulence Parameters

Abstract Acoustic sounder observations of atmospheric turbulence parameters presented in this paper include estimates of the dissipation rate ε, estimates of turbulent scale lengths λ, and uncertainties in measurements of the variance of the vertical wind σ2w caused by pulse volume filtering. The calculations are mainly restricted to periods when the convective regime is well established. Two techniques are used to determine ε and λ. Structure functions and the spectral variance of the echo are used to determine ε. The spectrum of vertical velocities are used to calculate λm and the autocorrelation function is used to calculate λe. Estimates of ε obtained from the spectral variance of the echo compare favorably with estimates from the structure function during convective regimes but the agreement is poor in other regimes. The autocorrelation function method for obtaining length scales yields results more reliably than the spectral method. The ratio λm/λe compares favorably with values reported in the literature except at low heights where it is markedly lower. The effects of pulse volume filtering on measurements of σ2w were found to be significant. In convective conditions, σ2w deduced from the Doppler shift of the echo can be underestimated by up to 25% and by greater amounts in other conditions.

Model identification of durability degradation process of concrete material and structure based on Wiener process

2020 ◽  
pp. 105678952096143
Author(s):  
Zhenhao Zhang ◽  
Minhan Liu ◽  
Xin Liu ◽  
Xiao Wang ◽  
Yi Zhang
Keyword(s):  
Elastic Modulus ◽  
Reinforced Concrete ◽  
Wiener Process ◽  
Autocorrelation Function ◽  
Function Method ◽  
Concrete Structures ◽  
Degradation Process ◽  
Dynamic Elastic Modulus ◽  
Concrete Material ◽  
Verification Method

The degradation and damage of concrete material and structure during their service life are significantly characterized by randomness, so it is of great importance to establish a stochastic process model for the structural durability degradation. This study was based on Wiener process to identify the durability degradation of concrete structures. Firstly, two identification methods for Wiener process were introduced, including autocorrelation function method and probability statistics verification method. The former is a rough method for preliminary identification, and the latter is a strict method for accurate identification. According to the degradation processes and damage mechanisms of dynamic elastic modulus of concrete and section stiffness of reinforced concrete girder, and based on relevant data, autocorrelation function method and probability statistics verification method were used to identify whether the degradation processes of concrete dynamic elastic modulus and girder section stiffness conform to Wiener process. The results showed that the degradation process of concrete dynamic elastic modulus and the degradation process of section stiffness of reinforced concrete girder can be modeled with Wiener process. The conclusions contribute to the prediction of performance degradation and the maintenance for concrete structures in service.

Estimation of Stellar Metal Abundance. II. A Recalibration of the C[CLC]a[/CLC] [CSC]ii[/CSC] K Technique, and the Autocorrelation Function Method

1999 ◽  
Vol 117 (2) ◽  
pp. 981-1009 ◽  
Author(s):  
Timothy C. Beers ◽  
Silvia Rossi ◽  
John E. Norris ◽  
Sean G. Ryan ◽  
Thomas Shefler
Keyword(s):  
Autocorrelation Function ◽  
Function Method ◽  
Metal Abundance

Log-log scale roughness spectroscopy of surfaces

1993 ◽  
Vol 51 ◽  
pp. 224-225
Author(s):  
P. Fraundorf ◽  
B. Armbruster
Keyword(s):  
Power Spectrum ◽  
Autocorrelation Function ◽  
Power Spectra ◽  
Scanning Force Microscopy ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Scanning Force ◽  
Lateral Structure ◽  
Scale Roughness

Optical interferometry, confocal light microscopy, stereopair scanning electron microscopy, scanning tunneling microscopy, and scanning force microscopy, can produce topographic images of surfaces on size scales reaching from centimeters to Angstroms. Second moment (height variance) statistics of surface topography can be very helpful in quantifying “visually suggested” differences from one surface to the next. The two most common methods for displaying this information are the Fourier power spectrum and its direct space transform, the autocorrelation function or interferogram. Unfortunately, for a surface exhibiting lateral structure over several orders of magnitude in size, both the power spectrum and the autocorrelation function will find most of the information they contain pressed into the plot’s origin. This suggests that we plot power in units of LOG(frequency)≡-LOG(period), but rather than add this logarithmic constraint as another element of abstraction to the analysis of power spectra, we further recommend a shift in paradigm.

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