Occurrence and Detection of Killer Yeasts on Chenin Blanc Grapes and Grape Skins

Two hundred and thirty killer yeast strains were selectively isolated from Chenin blanc grapes and grape skins collected from six wineries. The killer yeasts were divided into nine groups based on their colony morphology and colour on modified Wallerstein laboratory nutrient agar. All strains fermented Chenin blanc grape must (pH 3,5; 40 mg/ I free SO, and 5% (v/v) ethanol) at l4°C. Existing techniques in which methylene blue are used were evaluated to detect killer yeasts, to determine interactions between different killer phenotypes, and to determine the sensitivity of commercial strains to the killer toxins

A PC-BASED MODEL FOR EVALUATION OF INVESTMENT IN MANUFACTURING EQUIP:MENT

<p>ENGLISH ABSTRACT: The investment in advanced manufacturing equipment must be evaluated on two levels, ie. a general technical investigation, and an in-depth technical and economical analysis if necessary. This is especially true for a country like South Africa where new technologies like robotics are relatively untried . It is therefore important to choose a suitable framework for both technical and economic analyses. This framework forms the foundation of the discussed evaluation model. For practical use, the evaluation and choice process is programmed for use on a PC.</p><p>AFRIKAANSE OPSOMMING: Belegging in toerusting vir gevorderde vervaardiging word gewoonlik op twee vlakke geevalueer, nl. 'n algemene tegniese ondersoek en 'n deeglike tegniese en ekonomiese ontleding, indien vereis. Dit is veral waar in 'n land soos Suid-Afrika waar nuwe ontwikkelings soos robotika nag relatief onbekend is. Dit is dus belangrik om 'n gepaste raamwerk te kies vir beide die tegniese en die ekonomiese ontledings. Hierdie raamwerk is die basis van die ontledingsmodel wat bespreek word. Om toepassing te vergemaklik, word die ontledings- en keuseprosesse geprogrammeer vir 'n mikrorekenaar.</p&gt

MASJIENVISIE AS OUTOMATISERINGSOPSIE VIR SUID-AFRIKAANSE NYWERHEDE

<p>ENGLISH ABSTRACT: Indien Automation can effectively improve productivity. A recent shift from hard to flexible automation boosted the robotics and machine vision technology as options for implementation.<br />The principle of machine vision is still new in South Africa and it was therefore neccessary to create a conceptual base which includes aspects of image capturing, image analysis, image interpretation and calibration.<br />The final step of this research program was to investigate the application and justification of vision in various fields.</p><p>AFRIKAANSE OPSOMMING: Indien Suid Afrika sy produktiwiteit wil verbeter, is outomatisasie 'n werkbare opsie. Die klemverskuiwing van harde na aanpasbare outomatisasie het veroorsaak dat die tegnologie rondom robotika en masjienvisie in belangrikheid toeneem.<br />Omdat die masjienvisiekonsep nog relatief onbekend in Suid Afrika is, was dit ncdig om eers die beginsels rondom die konsep neer te Ie. Dit sluit aspekte soos beeldverkryging, beeldanalise, beeldinterpretasie en kalibrasie in.<br />As 'n finale stap is gekyk na die toepassing van masjienvisie in verskeie velde asook die regverdiging daarvan.</p&gt

On placing the reflection plane in numeric inductance calculations of thin-film superconducting structures using the method of images

Determining the inductance of thin film superconducting structures accurately is extremely important in sub-Terahertz superconducting logic circuits. For numeric analysis, both the structure and ground plane need to be sufficiently segmented. The method of images significantly reduces the number of segments, but the selection of the position of the reflection plane is critical. The influence of the position of the reflection plane on inductance is investigated, and results presented. A study of segmentation and filamentation is also made, and these results used to calculate the inductance of a complex three-dimensional structure.Conference Pape

A single-clock asynchronous input COSL set-reset flip-flop and SFQ to voltage state interface

Although published research in COSL has stagnated, it remains a useful logic family for interfacing the much faster RSFQ family to hot-logic circuits. COSL has always been plagued by the absence of latches, and previous attempts at implementing such latches were clumsy. A new COSL Set-Reset flip-flop is discussed here, and results shown. This asynchronous input latch, which can also be configured as a T flip-flop, can function on a single-phase clock. It was also adapted to convert SFQ output pulses from RSFQ logic circuits to voltage state levels that can be viewed on standard laboratory oscilloscopes. Due to the asynchronous nature of the inputs, the RSFQ-COSL converter is also more reliable than earlier DRO-to-COSL elements. © 2005 IEEE.Conference Pape

Comparison of genetic algorithms to other optimization techniques for raising circuit yield in superconducting digital circuits

Novel logic devices in the RSFQ and COSL superconducting logic families are most often sub-optimal. Before such devices can be incorporated into physical designs, they have to be optimized for high theoretical yield, and preferably for highest possible yield. Even simple logic gates can contain numerous inductors, resistors and Josephson junctions. During optimization, it is often needed to adjust all the element values. The search space is therefore very large, and genetic algorithms have been used with success to optimize such gates. The conversion of circuit file to genome for the genetic algorithms is discussed, as well as fitness evaluation through Monte Carlo analysis. Results with both novel and existing logic gates are presented. Other optimization techniques are also discussed in comparison to genetic algorithms.Conference Pape

On using genetic algorithms to optimize high frequency superconducting digital circuits for optimal yield

Even simple superconducting logic gates can contain tens of inductors, resistors and Josephson junctions. In order to increase the yield and reliability of such circuits to acceptable levels, it is often needed to adjust all the element values. The search space is therefore very large, and genetic algorithms have been used with remarkable success to optimize such gates.Conference Pape

Modeling superconducting components based on the fabrication process and layout dimensions

A procedure is described where the mask dimensions of superconducting components are used in SPICE simulations to predict the performance of a device. Thickness tolerances of the fabrication process, as well as mask bias offsets and mask tolerances are included in the component models. This makes it possible to predict circuit yield by Monte Carlo analyses, which are based on the fabrication process design rules. Model descriptions of all the components used in a standard superconductor multilayer process are given, and the accuracy of the models are verified. The superconducting components that are modeled include microstrip transmission lines, coupled transmission lines, resistors and Josephson junctions. The usefulness of this procedure is demonstrated by simulation results of a stack amplifier, where the yield of the circuit is calculated for the lumped element model and the proposed model, which includes parasitic elements.Conference Pape

Ultra high-speed superconducting RSFQ (Rapid Single-Flux-Quantum) digital switching logic

The simulation of existing and newly developed RSFQ components is discussed, and the results interpreted. These components represent data with picosecond voltage pulses. Amongst superconducting logic families, RSFQ promises to be the fastest. Theoretical operational limits are predicted as 300 GHz, 100 times faster than conventional semiconducting logic.Conference Pape