Determination of linear and nonlinear absorption of metallic colloids using photothermal lens spectrometry

2011 ◽  
Vol 28 (2) ◽  
pp. 281 ◽  
Author(s):  
A. Marcano O. ◽  
F. Delima ◽  
Y. Markushin ◽  
N. Melikechi
Keyword(s):  
Nonlinear Absorption ◽  
Linear And Nonlinear

Near-IR Spectroscopic Determination of NaCl in Aqueous Solution

1992 ◽  
Vol 46 (12) ◽  
pp. 1809-1815 ◽  
Author(s):  
Jie Lin ◽  
Chris W. Brown
Keyword(s):  
Aqueous Solution ◽  
Temperature Effects ◽  
Continuous Monitoring ◽  
Principal Component Regression ◽  
Principal Component ◽  
Standard Errors ◽  
Near Ir ◽  
Linear And Nonlinear ◽  
Ir Spectroscopic

The concentrations of NaCl in aqueous solutions have been determined with the use of near-IR spectra between 1100 and 1900 nm. Models expressing the concentration of NaCl are developed with linear and nonlinear regression with the use of the absorbances at selected wavelengths and with principal component regression (PCR) using entire spectra. Temperature perturbations on water bands interfere with the measurement of NaCl but can be removed by linear or nonlinear regressions using the absorbances at the wavelengths where the temperature effects are zero, or they can be accounted for by PCR. Standard errors of 5 mM and a detection limit of IS mM are obtained for NaCl. This technique can be applied for quantitative analysis of NaCl in the laboratory or can be readily adapted for continuous monitoring in process control.

Application of the cepstrum method for processing iridology television signals

2021 ◽  
Author(s):  
Keyword(s):  
Dynamic Range ◽  
Video Signal ◽  
Signal Power ◽  
Television System ◽  
Digital Correction ◽  
Linear And Nonlinear ◽  
Reading Beam

The questions of the cepstrum method application for the processing of iridology television signals are considered. A cepstrum method for processing a delayed video signal of an aerospace television system is proposed. The application of the method greatly facilitates the determination of the delay and expands the dynamic range of the corrected signal. An expression for determining the power cepstrum at different apertures of the reading beam is received and a suboptimal model of an ideal corrector is designed. Keywords aperture correction; digital correction; linear and nonlinear correctors; cepstrum method; aperture; Gaussian aperture; exponential aperture; signal power cepstrum

scholarly journals First-Principles Determination of the Polarizabilities of Carbon Tubules as a Function of Length

1994 ◽  
Vol 349 ◽  
Author(s):  
Andrew A. Quong ◽  
Mark R. Pederson
Keyword(s):  
First Principles ◽  
Density Functional ◽  
Valence Electron ◽  
Local Density ◽  
Density Approximation ◽  
Functional Theory ◽  
Size Dependent ◽  
The Density Functional Theory ◽  
Linear And Nonlinear

ABSTRACTWe use the local-density-approximation to the density-functional theory to determine the axial polarizabilities of fullerene tubules as a function of length and winding topologies. Specifically, we present linear polarizabilities for tubules of composition C12H24, C36H24, C40H20 and C60H24. The size-dependent variation in the dipole-coupled gaps between pairs of occupied and unoccupied levels leads to enhancements in the polarizability per valence electron as the length of the tubule increases. The results are compared to recent densityfunctional based calculations of the linear and nonlinear polarizabilities for fullerene and benzene molecules.

A Mixed Linear/Nonlinear Least-Squares Method for Determining Line Parameters from Noisy Spectra

1989 ◽  
Vol 43 (3) ◽  
pp. 558-566 ◽  
Author(s):  
Amedeo Premoli ◽  
Maria Luisa Rastello
Keyword(s):  
Raman Spectroscopy ◽  
Least Squares Method ◽  
Nonlinear Least Squares ◽  
Direct Analysis ◽  
Measured Data ◽  
Line Profiles ◽  
Linear And Nonlinear ◽  
Nonlinear Least Squares Method ◽  
Ir And Raman

The determination of the parameters characterizing line profiles embedded in a noisy spectrum is an important task in IR and Raman spectroscopy. A direct analysis from an inspection of the spectrum is often difficult in the presence of overlapped profiles and/or considerable background. This paper presents an algorithm based on alternate stages of linear and nonlinear optimization for extracting Lorentzians or Gaussians from the measured data, taking into account the presence of a frequency-dependent background superimposed onto white noise. The analysis of several experimental spectra shows the capability of the algorithm in discriminating noisy and partially overlapped profiles.

Linear and nonlinear absorption studies of polymethine, squaraine and tetraone dyes

2007 ◽  
Author(s):  
Scott Webster ◽  
Jie Fu ◽  
Olga V. Przhonska ◽  
Lazaro A. Padilha ◽  
David J. Hagan ◽  
...  
Keyword(s):  
Nonlinear Absorption ◽  
Absorption Studies ◽  
Linear And Nonlinear
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