Fig. 1 Schematic of the IoT/Fog laboratory-scale system developed to collect spindle health information for training and validating AI/ML classifiers More

Fig. 2 Equipment for laboratory-scaled spindle condition-based monitoring sensing system: (1) spindle, GDZ-80-1.5 C; (2) vibration sensor-wired, Willcoxon 789 A—thread mount (Vib-2); (3) vibration sensor-wireless smart sensor, TE8911—thread mount (Vib-1/TC-1); (4) acoustic pressure sensor (SND-1),... More

Fig. 3 Spectrum overall, g comparison in spindle operation modes at various rpm More

Fig. 4 Enveloping RMS comparison in spindle operation modes with various rpm More

Fig. 5 Skewness comparison in spindle operation modes with various rpm More

Fig. 6 Averaged Kurtosis comparison in spindle operation modes with various rpm More

Fig. 7 Crest indicator comparison in spindle operation modes with various rpm More

Fig. 8 Averaged spectrogram in various failure modes, spindle operating at 6000 rpm, normal operation (top left), imbalance (top right), ingression (bottom left), and crashed (bottom right) More

Fig. 9 Data from the smart sensor (TE8911) for various failure modes. Spindle operated at 6000 rpm. Normal operation (top left), imbalance (top right), ingression (bottom left), and crashed (bottom right). More

Fig. 10 Example of tracing the optimization, hyperparameters, and accuracy result with the grid method. The top 5% results are displayed. Possible activation functions were ReLU (0), LeakyReLU (1), or tanh (2). More

Fig. 1 Plan view of X-ray log scanners: ( a ) orthogonal scanning and ( b ) oblique scanning More

Fig. 2 Knot model reference diagram: 1 = plan view, 2 = axial view, and 3 = side view More

Fig. 3 Geometric parameters defining the location of a knot within a log More

Fig. 4 Schematic representation of a knot within an oblique scan: ( a ) plan view of the scanning arrangement and ( b ) axial view More

Fig. 5 Schematic representation of a knot observed in a radiograph More

Fig. 6 Scans from two orientations 90 deg apart with separate X-ray sources and detectors More

Fig. 7 Scanning apparatus used for data collection: ( a ) schematic cross section showing interaction between X-ray source and detector and ( b ) constructed cart used for data collection More