Fourier-based techniques

These sorted data can then be analysed using the power spectrmn of the output. This latter analysis forms the standard hack-end procedure of the Fourier-based techniques. 

Fourier-based techniques. For these methods, the input parameter realisations have to fulfil special frequency properties. Then a fi quency decomposition of the output maps different frequencies attributed to the input factors to different fractions of the variance of the output. Different frequency selection schemes have been developed, named Fourier Amplitude Sensitivity Test (FAST), Extended FAST (EFAST), and Random Balance Design (RBD). They can estimate first and/or total effects. 

Critten D.L. (1996) Fourier-based techniques for the identification of plants waA weeds. Journal of Agricultural Engineering Research, 64 149-154. 

Future development of spectroscopic structure-determination methods will depend on the availability of more powerful photon and particle sources as well as advances in photon and particle detectors. Impressive progress has been made in molecular structure determinations based on advances in computation power and in computational algorithms, such as fast Fourier-transform techniques, for nearly every form of spectroscopy and diffraction analysis. Hajdu and co-work-... 

Because chemical and structural properties of natural and artificial gems are very similar in this case, the possibilities of Raman and LIBS methods are rather limited. It was found that another laser-based techniques could be very effective for rapid spectroscopic discrimination between natural and synthetic emeralds, rubies, and alexandrite (Armstrong et al. 2000a,b). The first one is DRIFTS (Diffuse Reflectance Fourier Transformed Infra-Red Spectroscopy)... 

The foregoing has been a brief introductory discussion of NMR which has concentrated on some basic principles that are very useful in understanding the technique. The actual practice of NMR today is much more advanced. The incorporation of Fourier transform techniques has revolutionized NMR spectroscopy. All types of pulse sequences and two-dimensional (2D) techniques have been developed to provide even greater structural detail than has been discussed above. A discussion of such techniques belongs in a more specialized text, but it must be remembered that while these techniques are faster, more sensitive, and much more sophisticated, they are still largely based on the principles presented here, as is the interpretation of the results. 

Fourier transform techniques are used throughout the whole spectroscopic region, particularly in the infrared and visible. As we pass from the microwave region to the far-infrared, Fourier transform methods are still used, but based now on interferometry rather than pulsed methods. Perhaps this region of the spectrum will, in... 

Fourier transform technique Lewis acid catalysis Schiff base measurement... 

Several N2-N2 intermolecular potentials were examined with respect to their herringbone transition temperature under otherwise identical conditions based on canonical Monte Carlo simulations with 900 classical N2 molecules [217]. The simulations were performed in strictly two dimensions and the centers of mass were fixed on a triangular lattice. No finite-size extrapolations whatsoever were performed so that the transition temperatures obtained from the heat capacity maxima are only of a qualitative nature. The N2-graphite interaction was modeled by the first-order Fourier expansion technique [324, 326, 327] and is included only for the realistic atom-atom... 

Infrared-based techniques are used to identify molecules on the surface. IR radiation is used to excite vibrational modes in molecules in the gas phase or adsorbed on a surface. The transmitted or reflected IR spectrum can be analyzed in a spectrometer. Considerable improvement in the sensitivity can be achieved by use of Fourier transform infrared (FTIR) spectroscopy. Attenuated total reflection (the ATR-FTIR method) inside a crystal (germanium) of high refractive index can be used to further enhance the surface sensitivity (using the evanescent field). 

FTIR is similar to Raman spectroscopy in that it also uses molecular bond vibration for chemical species identification. In particular, though, in EUR the resonant frequency of bond vibration after exposure to infrared radiation is detected as an identifier for the species under examination. Fourier transform techniques are based on measurement of... 

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