Projects, graphic representations analysis

The most important method for exploratory analysis of multivariate data is reduction of the dimensionality and graphical representation of the data. The mainly applied technique is the projection of the data points onto a suitable plane, spanned by the first two principal component vectors. This type of projection preserves (in mathematical terms) a maximum of information on the data structure. This method, which is essentially a rotation of the coordinate system, is also referred to as eigenvector-projection or Karhunen-Loeve- projection (ref. 8). 

The graphical representation of AE data that has been localized in 3D is a very important aspect of acoustic emission analysis. There are several ways to visually represent the data. A common approach is to draw projections of the x/y, y/z or x/z planes. The representation in a 3D coordinate system, as shown in Fig. 5.15, can lead to useful insights when the graphical data is animated - such features are implemented in most modem AE data analysis software. Representing 4D data (three coordinates of the sources and the time of occurrence of all events) using print media, however, is difficult. 

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