Showing papers by "Defence Science and Technology Laboratory published in 1995"
01 Feb 1995
TL;DR: In this article, the authors analyzed the effect of additive noise on the sensitivity of the intensity measure to texture changes, described in terms of relative variance, and compared the performance of a variety of texture measures with respect to the bias in the estimated order parameter for absolute classification and relative variance for texture segmentation.
Abstract: The paper addresses the characterisation of high resolution radar image textures in the presence of additive noise, which is inevitably present in the system. Two possible goals are analysed. In the first, the authors consider absolute texture description and identify the extent to which noise degrades performance by introducing a bias. The second is concerned only with segmenting the texture into locally different regions and discusses the effect of the noise on the sensitivity of the measure to texture changes, described in terms of relative variance. Initially, the authors demonstrate that estimates of the mean, normalised log and contrast of the intensity approximate a sufficient statistic for K-distributed clutter. They then compare the performance of a variety of texture measures in terms of the bias in the estimated order parameter for absolute classification and the relative variance for texture segmentation. A normalised log measure is shown to have the best sensitivity overall. However, with additive noise an amplitude contrast measure yields a much smaller classification error with only slightly reduced sensitivity.
27 citations
TL;DR: The nucleotide sequence of the NS5 gene from Banzi virus was determined and the predicted amino acid sequence was elucidated and it was suggested thatBanzi virus is most closely related to the mosquito-borne flaviviruses and, in particular, yellow fever virus.
Abstract: Banzi is a mosquito borne flavivirus which belongs to the Uganda S serocomplex. No nucleotide sequence data have previously been reported from any virus of this serocomplex. We have determined the nucleotide sequence of the NS5 gene from Banzi virus and the predicted amino acid sequence was elucidated. Previously identified conserved RNA polymerase, methyltransferase and flavivirus NS5 amino acid motifs were present in the Banzi virus NS5 protein. These data add to the evidence for the functional importance of the regions. The encoded amino acid sequence was compared with the predicted amino acid sequence of other flavivirus NS5 proteins. Analysis of these sequences suggested that Banzi virus is most closely related to the mosquito-borne flaviviruses and, in particular, yellow fever virus. This pattern of similarity is in accordance with the previously suggested serological classification of flaviviruses.
9 citations
TL;DR: In this article, the effect of interference on the Seraphin coefficients of the alloy layer is shown to be the cause of the line shape variation, which justifies the use of Aspnes' low field theory in the analysis.
Abstract: Photoreflectance spectra have been obtained both from uncapped epilayers of strained Si1−XGex and from epilayers buried under a Si cap for 0·06 < × < 0·26. Fitting with Lorentzian line shapes yields E1 and E1 + ∆1/E0′ critical point transition energies in good agreement with those obtained by fitting to differentiated dielectric function spectra. This justifies the use of Aspnes' low field theory in the analysis. A previously reported discontinuity in oscillator strength for 0 < × < 0·09 is confirmed and attributed to a crossing in the E0′ and E1 + ∆1 transitions. Samples having a buried alloy layer exhibit a dominant Si peak not observed for the uncapped epilayers and a variation in SiGe line shape across a sample. The effect of interference on the Seraphin coefficients of the alloy layer is shown to be the cause of the line shape variation. The associated critical point transition energies, however, show a variation of <1% in equivalent Gefraction across a sample wafer.MST/3296
2 citations