Effective atomic number of Mn–Co–Fe2O3 ternary alloys using the Rayleigh to Compton scattering ratio

The objective of this work is to determine effective atomic number (Zeff) of Fe2O3(0.2)–Mnx–Coy (x + y = 0.8) ternary alloys using scattering of gamma photons and to compare available methods used to calculate Zeff. For this purpose, we have developed a fitting equation using the ratio of Rayleigh (R) to Compton (C) scattering intensity, R/C for the calculation of effective atomic number of ternary alloy (i.e., Mn–Co–Fe2O3). R and C scattering intensities for the given materials have been measured using a mono-energetic beam of 59.54 keV gamma rays and a scattering angle of 130° (x = 4.36 Å−1). The R/C ratios of elements with 20 ≤ Z ≤ 30 were used to constitute the best fit equation. R/C scattering ratios, when plotted as a function of atomic number, results in a fitted equation, which is then used for derivation of Zeff of the alloys. Also, experimental R/C values were used to determine effective atomic number of the alloys by using interpolation procedure. For comparison, Zeff of alloys were also calculated using different methods. Maximum relative differences between Zeff for experimental and theoretical results were found to be ≤8.04% (exp. 1 (fitting) versus method 6) and were found to be ≤8.99% (exp. 2 (interpolation) versus method 7) indicating a good agreement for the chosen alloys.

Method of Adjustments versus Method of Constant Stimuli in the Quantification of Accuracy and Precision of Rendered Depth in Head-Mounted Displays

The utilization of head-mounted displays (HMDs) in high-end applications such as medical, engineering, and scientific visualization necessitates that the position of objects be rendered accurately and precisely. Accuracy and precision of rendered depth for near-field visualization were measured in a custom-designed bench prototype HMD. Experimental results were compared to theoretical predictions established from a computational model for rendering and presenting virtual images by Robinett and Rolland (1992). Such a theoretical model provided the necessary graphics transformations required so that rendered virtual objects be perceived at the rendered depth in binocular HMDs. Three object shapes of various sizes were investigated under two methodologies: the method of constant stimuli modified for random size presentation and the method of adjustments. Results showa2mm and an 8 mm performance for the accuracy and the precision of rendered depth in HMDs, respectively. Results of the assessment of rendered depth in HMDs for near-field visualization support employing the method of adjustments over the method of constant stimuli whether or not the method of constant stimuli is modified for random size presentation.