Peaks, triangular shaped

The blast load is modeled as a triangular-shaped overpressure time curve. The blast overpressure rises instantaneously to the peak overpressure, B, then decays linearly with a blast pressure duration, T. The pressure is uniformly distributed over the surface of the plate and is applied perpendicular to the pane. 

In order to use the dynamic response charts based on a triangular shaped load, the bilinear pressure-time curve shown in Figure 3.7 can be simplified to an equivalent triangle. This equivalent load is computed by equating the impulse for each load shape and using the same peak pressure, Pt. The impulse, I, under the bilinear pressure-time curve is ... 

As columns are overloaded for preparative work, peak shape often deviates from the Gaussian shape typical of analytical work. In preparative work, the peaks can assume a triangular shape because the adsorption isotherm is nonlinear. A typical isotherm is shown in Figure 6-37, where CM is the concentration of sample in the mobile phase and Cs is the concentration of sample in the stationary phase. At low concentration of sample (CM) there is a linear adsorption isotherm which results in Gaussian peak shapes. At a point when either the sample adsorption in the stationary phase or the sample solubility in the mobile phase becomes limited, the isotherm becomes nonlinear, assuming either a convex or a concave shape. Convex isotherms are the most common and result in peak tailing. Conversely, concave isotherms cause fronting of the peaks. 

The spectra obtained for ice Ih, LDA and HDA, using the TFXA spectrometer at 10K [53] is shown in Fig. 11. Ice Ih is the most common and readily obtainable phase of ice which has now been well studied [14,15,48,49]. Its spectrum has a very simple structure, the translational modes below 40 meV are well separated from the librational modes (or hindered rotations) in the energy region between 65-125 meV (very few system shows similar behaviour and this is due to the large mass difference between O and H). The observed acoustic phonon peak is at 7 meV. The two sharp peaks at 28 and 37 meV are the optic-phonon bands and have an unusual triangular-shape. In contrast, only a single feature appears in the IR spectrum, at 27 meV, and the Raman spectrum has an additional shoulder at 36 meV (see Fig. 10). 

In fig. 19 results for the valence PES spectra of the Ce pnictides are shown (Gunnarsson and Schonhammer 1985b). The off-resonance spectra of the pnictides show spectra with a peak at — 2eV. For simplicity we have therefore used a simple triangular shape for V eY as shown in the insert. The figure shows results for both U = CO and for a finite U. In this case the finite U effects have a small influence on the spectra. The weight of the Kondo peak is also negligible. In these cases the hybridization effects dominate. The same conclusion was reached by Sakai et al. (1984). 

Although the bulk properties of 5f-electron heavy fermions are entirely similar to those of 4f-electron heavy fermions (see, for example, Stewart 1984), the respective photoelectron spectra appear substantially different (an excellent review of the early work is given by Allen 1992). Unlike the triple-peaked 4f spectra in Ce compounds (the /° and / states within the SIM interpretation), measurements at the 6d absorption edge where the 5f signal is enhanced, generally yield a rather broad, triangular shaped spectrum... 

If too much of analyte is injected, its peak can be distorted into a triangular shape exceeding the... 

The first symptom of mass overload is seen as a broadening of the chromatographic peak as the mass of sample is increased. This is measured as a lowering of the efficiency (reduction in the number of theoretical plates) and increase in peak asymmetry, but as mass load is increased it often results in triangular shaped peaks which show typically a peak maximum at a reduced retention time and a tail which extends to the retention time of a peak resulting from an analytical load. Other, much more bizarre peak shapes can also be found. These represent cases where special interactions between the solute molecules and the stationary phase, the mobile phase or each other occur. 

In a well-tuned (adjusted) instrument, the shape of a mass spectral peak is approximately triangular (Figure 44.7a), but, in an instrument that is poorly tuned the peak will appear misshapen (Figure 44.7b). Usually, the cause of the skewing of the peak arises from incorrectly adjusted... 

Knox and Piper (13) assumed that the majority of the adsorption isotherms were, indeed, Langmuir in form and then postulated that all the peaks that were mass overloaded would be approximately triangular in shape. As a consequence, Knox and Piper proposed that mass overload could be treated in a similar manner to volume overload. Whether all solute/stationary phase isotherms are Langmuir in type is a moot point and the assumption should be taken with some caution. Knox and Piper then suggested that the best compromise was to utilize about half the maximum sample volume as defined by equation (15), which would then reduce the distance between the peaks by half. They then recommended that the concentration of the solute should be increased until dispersion due to mass overload just caused the two peaks to touch. 

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