✍ Scribed by Michael Sjögren; Hang Li; Ulf Rannug; Roger Westerholm
No coin nor oath required. For personal study only.
Ten different diesel fuels were tested for 26 physical and 45 chemical parameters. Principal components analysis (PCA) was used for statistical analysis of the physical and chemical data separately and combined. Physically, these and similar fuels may be described in a few general terms, such as viscosity, boiling residue, cetane number and density. With three PCs, 88% of the variation in physical terms was accounted for.
Only one fuel remained poorly described by the model. The most descriptive chemical components include I-methylphenanthrene as representative of a major fraction of the polycyclic aromatic hydrocarbons (PAH). With three PCs, all fuels were well accounted for, with 80% of the variation in chemical parameters explained. Although PCA does not provide a means of deriving causal relations, it may be used to find patterns of intercorrelated variables. With both chemical and physical parameters included in a final PCA, relations between chemical contents and physical characteristics were observed for e.g. PAH/olefins/naphthenes and viscosity.
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Kernel number, individual kernel weight, individual kernel volume, crude fat, crude protein, reducing sugars, starch content, amylose/amylopectin ratio and fatty acid composition were determined for six popcorn hybrids, grown in Colorado or Nebraska and harvested in 1997. The popcorn hybrids were A3
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