Sample loading terms, plots

Information about relation among variables in samples belonging to a data set can be obtained from an examination of plots of the sample loading terms (ill i vs these plots... 

Creep is a measure of sample length as a function of time when the sample is subjected to a constant load. Normally, creep curves are obtained by plotting data in terms of sample length, strain, or compliance versus log (time), as illustrated in Figure 2. The basic nature of creep curves is explained at the molecular level as a distortion of bond... 

This condition is the zero creep point, when the surface forces represented by the terms on the right hand side of equation (4) are exactly balanced by the force due to the load imparted to the sample (Fq). Physically, there would be neither contraction nor elongation when this situation occurs. For this reason, the force at or approaching the zero creep point is difficult to measure directly. Therefore, the force at the zero creep point is determined by measuring the strains of several loaded samples and plotting these strains against the stress which caused them. The force at the zero creep point is determined by interpolation. 

A correlation between two variables can be either positive or negative. The interpretation of the factors in terms of patterns in the samples is the most difficult part and not always possible. However, a particular combination of m/z values in a mass spectrum can be indicative of the presence of a chemical compound in the sample. A tool for interpretation, similar to that utilized to interpret canonical variates, is the factor spectrum with intensities Si bij (where Si is the standard deviation of each column in the data matrix X). This spectrum, plotting the values Sj bij at m/z, shows the part of the intensity change described by the factor. In other words, such a spectrum will show those masses that contribute the most to the discrimination of the samples. Because the loadings b j generally can be either positive or negative, the factor spectrum exhibits positive and negative intensities. 

Creep tests are run by subjecting a grouted soil sample to a sustained load less than the short-term Unconfined Compression strength, until failure occurs. As the sustained load decreases in value, the time to failure increases. Data from such tests plot as shown in Fig. 11.22, and indicate an asymptote at what may be called a creep endurance limit. For acrylamides these values will range from as low as 20% Unconfined Compression for triaxial tests at low lateral pressure to as high as 40% for triaxial tests at at rest lateral pressures. (For silicates, values may be taken from Fig. 11.11.)... 

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