The metrics of squared Laplace image (3 ms), Mendelsohn and Mayall (3 ms), Riemann tensor (5 ms), steepness (8 ms) and maximal gradients (13 ms) have been tested.
(4) Steepness: this measure shows quickly the sense scores drop across labels.
Therefore S4 (steepness) was selected as a reliable indicator for aberration correction during PIV measurements.
Except S4 (steepness) all other metrics exhibit a double-peak behavior whose maxima metric values do not correspond to sharp images.
The current model consists of many parameters: 39 weight values (for one option: k = i = 1): ω i, a time step size: Δt, slow and fast speed factors: γ, 17 steepness: σ i, and 17 threshold: τ i.
A beam splitter (BS) reflects the modulated light which is focused by a lens (L) to a CCD camera Table 1 Sharpness metric calculation time for a single image Metric Type Calculation time S1 Squared Laplace image 3 ms S2 Mendelsohn and Mayall 3 ms S3 Riemann tensor 5 ms S4 Steepness 8 ms S5 Maximal gradients 13 ms.
The models have been designed using results of the set of steady numerical simulations computed by k–∊ V2F turbulence model for various configurations defined by selection of ratio H/λ in range from 0.6 to 1.4, steepness ratio λ/a in range from 20 to 200 and bulk velocity Ub in range of Reynolds number Re= HUb/ν from 3830 to 89,366.
By looking at the astigmatism behavior, which should give zero amplitude value for Z5 and Z6 (Fig. 4(b) and (c)) it turns out that only metric S4 (steepness) performs well since the other metrics detect two symmetric Z5 and Z6 values as optimum that do not correspond to sharp images.
We also calculated steepness, based on normalized David's scores [Gammell et al., 2003], which measures the degree to which individuals differ in their ability to win contests [de Vries et al., 2006]: steepness can vary from 0 (no average difference) to 1 (maximum average difference).
Table 2 Optical properties of ZnS Mn Optical properties ZnS Mn (4 %) Band gap from PL 3.50 eV Band gap from absorption spectrum 3.00 eV Urbach energy 121 meV Steepness parameter 0.29.
