This paper describes an investigation into the accuracy with which values on n, k and d for a thin film may be determined assuming a given accuracy in the measurement of the photometric parameters Rp, Rs, Tp and Ts. It was observed that, in all cases, there was a considerable volume of uncertainty in n, k, d space round the true point, this volume being in the form of a long parallelepiped. These conclusions were tested by processing the experimental data by a number of numerical iteration processes.
The results of investigation of the variation of radio signal strengths during the solar eclipse on July 22, 2009 are reported in this paper. Observations of the radio signals transmitted from different radio stations at different frequencies and received at a particular observing site indicate a distinct change in signal strength around the time the eclipse umbra passes the propagation paths. The three types of variations in the eclipse day and particularly during its peak period are different from propagation under normal condition. The phenomena of signal variations, the noted "Inverted U-shape" at one of the frequencies before the occurrence of the eclipse and 13 to 15 minutes time difference between the enhancement of the signal strength and the onset of eclipse are some interesting characteristics. The results are interpreted by ionospheric D-layer behavior at such times.
A modified form of the Nelder and Mead simplex hill-climbing technique has been applied to the calculation of n, k and d for thin metallic films from measurements of Rp, Rs, Tp and Ts. In order to obtain consistent results it was found necessary, in addition, to include an error term in the objective function so that the known approximate value of d could be used in the calculations.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.