Superconducting COSL building blocks for implementation in ultra-high speed logic circuits

Complementary output switching logic (COSL) is used to define building blocks for ultra-high speed (approx. 20 GHz) logic circuits. The family consists of the standard logic functions OR, NOR, AND, NAND and XOR. The building blocks include a new single gate inverter and various latch functions. Changes in the layout of the COSL gates are proposed to improve the uniformity of current distribution in the gates, which will, in turn, prevent unwanted field concentrations.Conference Pape

Multi-domain Gunn diodes with multiple hot electron launchers: a new approach to mm wave GaAs Gunn oscillator optimization

The optimization of millimeter wave Gunn oscillators comprises two avenues, namely the use of heterojunctions for hot electron injection and multi-domain operation Gunn diodes. A combination of these two techniques is proposed resulting in multiple hot electron launchers spaced throughout the diode. The results presented here suggest that this configuration proves to be a very promising option which warrants further investigation.Conference Pape

Non-destructive measurement of internal quality of apple fruit by a contactless NIR spectrometer with genetic algorithm model optimization

Spectrometric methods based on near infrared radiation (NIR) are commonly used effectively in the agricultural and food industry. However, these methods still face limitations whereby meeting requirements for application such as nondestructive quality testing of large fruits and automated sorting and grading is still a challenge. A Fourier transform (FT)-NIR spectrometer (emission head, EH mode of Matrix-F) that simulates on-line sample scanning (contactless, large sample size (100 mm)) was used to predict internal properties of apple fruit. The EH was compared to laboratory multipurpose analyzer (MPA) FT-NIR spectrometer using two contact-sample presentation modes with relatively smaller sample size (≤22 mm); namely, the integrating sphere (IS) and the solid probe (SP). Three apple cultivars (Golden Delicious, Granny Smith and Royal Gala) sourced from two retail stores (in Stellenbosch, South Africa) were used to constitute variability in the sample set. Partial least squares regression (PLSR) prediction models for internal quality (total soluble solids (TSS) and titratable acidity (TA)) were developed and validated on external test samples in various scenarios. Genetic algorithm (GA) based optimization of PLS models was used to produce optimal models prior to instrumental comparison.Model optimization using GA improved performance by a margin of 30% of the original root mean square error of cross validation for the contactless system bringing it closer to the performance of models from the MPA. The EH's performance makes it an attractive option for achieving on-line application of NIR spectroscopy for sorting apples based on internal quality. Keywords: FT-NIR, Calibration transfer, Model performance, Genetic algorithm, Apple qualit