Direct determination of improved contraction coefficients by a least-squares approach

1981 ◽  
Vol 20 (S8) ◽  
pp. 63-71
Author(s):  
P. Graf ◽  
E. L. Mehler
Keyword(s):  
Least Squares ◽  
Direct Determination ◽  
Least Squares Approach

Effect of the Water Spectrum on the Determination of Dissolved Ammonia, Urea, and Chloride Concentrations by Raman Spectroscopy

1998 ◽  
Vol 52 (2) ◽  
pp. 240-249 ◽  
Author(s):  
Hsiaoling Wang ◽  
Chao Wang ◽  
Charles K. Mann ◽  
Thomas J. Vickers
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
The Other ◽  
Ammonium Salts ◽  
Ammonium Ion ◽  
Water Band ◽  
Chloride Concentrations ◽  
Better Than ◽  
Least Squares Approach

The effect of large, changing concentrations of electrolytes on the behavior of the OH stretching band of water have been investigated with the aim of developing methods for compensating for spectral interferences when solute NH bands are made the basis for mixture analyses. With the use of urea and ammonium salts as analytes, it was found that changing electrolyte concentrations affect the shape of the water band but do not appreciably affect the shapes of either the ammonium ion or urea Raman lines. Chlorides, nitrates, and mixtures of these were used as electrolytes. The identity of the anion had a significant effect on the shape of the OH band. Two methods of compensation were used. One involved factor analyzing the spectra of a set of solutions that contained chlorides and nitrates that are Raman inactive in the vicinity of the OH stretching band. The principal abstract factors were used in place of a water reference for a least-squares mixture analysis. The other method was application of partial least-squares. In addition to urea and ammonium ion, the concentration of KCl and the ionic strength of the system can be determined in the partial least-squares approach with limits of detection better than 0.1 M.

On: “A least‐squares approach to depth determination from gravity data” by O.P. Gupta (GEOPHYSICS, 48, 357–360, March 1983)

Geophysics ◽  
1990 ◽  
Vol 55 (3) ◽  
pp. 376-377 ◽  
Author(s):  
El‐Sayed M. Abdelrahman
Keyword(s):  
Nonlinear Equation ◽  
Least Squares ◽  
Gravity Anomaly ◽  
Gravity Data ◽  
Residual Gravity ◽  
Depth Determination ◽  
Residual Gravity Anomaly ◽  
Least Squares Approach

In the article by Gupta, the problem of depth determination of a buried structure from the residual gravity anomaly has been transformed into a problem of finding the solution of a nonlinear equation of the form f(z) = 0. Gupta begins his formulation of the problem with equation (1) from Mettleton (1942) Eq. (1) [Formula: see text]

scholarly journals High Precision Astrometry over Large Angular Scales with Closure Constraints: the Triplet 1803+784/1928+738/2007+777

1996 ◽  
Vol 175 ◽  
pp. 120-121
Author(s):  
E. Ros ◽  
J.M. Marcaide ◽  
J.C. Guirado ◽  
T.P. Krichbaum ◽  
R.A. Preston ◽  
...  
Keyword(s):  
Least Squares ◽  
High Precision ◽  
Radio Sources ◽  
Phase Cycle ◽  
Parameter Values ◽  
Precision Astrometry ◽  
Closure Constraints ◽  
Closure Constraint ◽  
Least Squares Approach

The technique of differential astrometry using the phase-delay VLBI observable promises fractional precisions of ≃2 × 10–9 in the determination of the separation of sources 5° or 6° apart on the sky (Guirado et al. 1995a; Lara et al. 1996). In our present research we seek further improvement in this technique through using triplets of radio sources, which provide a closure constraint in the determination of relative angular positions. This constraint not only eases the resolution of the phase-cycle ambiguities (a major problem in the least-squares approach to astrometry with phase delays), but it also strongly constrains the space of allowable parameter values.

Application of Mid-Infrared Transmission Spectrometry to the Direct Determination of Glucose in Whole Blood

1998 ◽  
Vol 52 (6) ◽  
pp. 820-822 ◽  
Author(s):  
R. Vonach ◽  
J. Buschmann ◽  
R. Falkowski ◽  
R. Schindler ◽  
B. Lendl ◽  
...  
Keyword(s):  
Least Squares ◽  
Partial Least Squares ◽  
Whole Blood ◽  
Direct Determination ◽  
High Water ◽  
Calibration Model ◽  
Infrared Transmission ◽  
Ir Transmission ◽  
Background Absorption

The capability of FT-IR transmission spectrometry was examined for the direct determination of glucose in whole blood without any sample preparation. For these investigations, the whole blood samples were automatically aspirated by a syringe pump into the transmission cell. Infrared spectra were recorded in the 1500–900 cm−1 range. Despite the high water background absorption and the complex blood matrix, significant spectral changes due to different glucose concentrations were observed. Chemometric (partial least-squares) models were applied for the determination of glucose. A standard error of calibration of 13.8 mg/dL was obtained by using a partial least-squares calibration model containing five ranks. The residues for an independent test set were less than 15 mg/dL.

Sign in / Sign up

Export Citation Format

Share Document