Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Assessing the quality of fruit has become vitally important for farmers and
growers. With retailers placing ever stricter requirements on fresh produce,
growers have to spend a greater amount of time and effort sorting and grading
their harvest. Increasingly, vendors are placing requirements not only on
external factors like colour, and firmness, but on internal quality factors such
as sugar content and acidity, because, although consumers buy fruit based on
their external appearances, the taste of the fruit is what determines whether
the consumer will buy again. Different techniques exist that probe the internal
quality of fruit non-destructively. The technique most widely used today
is Near Infrared Spectroscopy. This technique is powerful, but has certain
limitations such as poor reliability and the need for constant recalibration.
This thesis suggests an alternative method for evaluating internal fruit quality
based on low-field nuclear magnetic resonance detected by superconducting
quantum interference devices. It introduces the theory of SQUIDs and NMR,
and evaluates the use of SQUID detected NMR spectroscopy as a method
for determining the internal quality of fruit. The fabrication techniques and
processes are explained in detail and a design for a SQUID detected NMR
spectrometer is given. Relevant simulations and simulation results are also given. No working SQUID could be fabricated and, as such, no working NMR
spectrometer was demonstrated. This thesis serves as a reference work for
future research. / AFRIKAANSE OPSOMMING: Bepaling van die gehalte van vrugte het vir boere uiters belangrik geword.
Met kleinhandelaars wat al strenger vereistes plaas op vars produkte moet
boere meer tyd en inspanning bestee met die sortering en gradering van hul oes.
Handelaars plaas nie net vereistes op eksterne kwaliteitsfaktore soos kleur en
fermheid nie, maar begin al hoe strenger vereistes plaas op interne kwaliteitsfaktore
soos suikerinhoud en suurgehalte, want, hoewel verbruikers vrugte koop
op grond van hul eksterne kwaliteitsfaktore, is dit die smaak van die vrug wat
bepaal of die verbruiker weer die vrug sal koop. Verskillende tegnieke bestaan
wat die interne kwaliteit van vrugte op ’n nie-destruktiewe manier kan bepaal.
Die mees algemene tegniek is Naby Infrarooi Spektroskopie. Hierdie tegniek is
kragtig maar het sekere beperkings soos swak betroubaarheid en die noodsaaklikheid
van konstante herkalibrasie. Hierdie tesis stel ’n alternatiewe metode vir
die evaluering van interne vrugkwaliteit gebaseer op lae-veld kernmagnetiese
resonans waargeneem deur supergeleidende kwantum inmenging toestelle voor.
Dit stel die teorie van SKWITs en KMR bekend, en evalueer die gebruik van
SKWIT-bespeurde KMR spektroskopie as ’n metode vir die bepaling van die interne kwaliteit van vrugte. Die fabrikasie tegnieke en prosesse word in detail
verduidelik en ’n ontwerp vir ’n SWKIT opgevangde KMR spektrometer word
gegee. Toepaslike simulasies en simulasie resultate word ook gegee. Geen werkende
SKWIT kon vervaardig word nie en as gevolg daarvan kon geen werkende
KMR spektrometer gedemonstreer word nie. Hierdie tesis dien as ’n naslaan
werk vir toekomstige navorsing.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5208 |
| Date | 12 1900 |
| Creators | Van Zyl, Derrick Steven |
| Contributors | Perold, W. J., University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 275 p. : ill. |
| Rights | University of Stellenbosch |
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