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Near infrared hyperspectral image analysis has been used to classify individual wheat grains representing 24 different Australian varieties as sound or as being discoloured by one of the commercially important blackpoint, field fungi or pink stains. The study used a training set of 188 grains and a test set of 665 grains. The spectra were smoothed and then standardised by dividing each spectrum by its mean, so that the analysis was based solely on spectral shape. Penalised discriminant analysis was first used for pixel classification and then a simple rule for grain classification was developed. Overall classification accuracies of 95% were achieved over the 420-2500 nm wavelength range, as well as reduced ranges of 420-1000 nm and 420-700 nm.

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A rigorous formulation is used to calculate the transmission properties of a thin, perfectly conducting biperiodic capacitive mesh on a dielectric boundary. The formulation is analogous to the well-known modal method used for inductive meshes, with the modal electric fields replaced by modal currents. Measurements made at submillimeter wavelengths are presented for square capacitive meshes on a crystal quartz substrate (n = 2.1). These measurements are shown to be in good agreement with the theory. The applicability of simple equivalent circuit models is investigated and the variation of the equivalent circuit parameters with the refractive index of the substrate is discussed. A modified expression of Babinet's principle is presented which is valid in the nondiffracting region for thin meshes on a dielectric interface.

Arrays of both annular and square annular slots in a conducting sheet on a dielectric substrate have been fabricated photolithographically. The structures are shown to behave as bandpass filters in the far infrared, with a resonant wavelength slightly larger than the average circumference or perimeter of the slot. The measured far-infrared transmittance of the annular array is approximately 76% of that predicted by theory, while its resonant frequency agrees with theory to within 5%.