Apparatus, systems and methods are provided for digital phase-locked loops. The method further including comparing the well data to the experience data set and developing an initial drilling tool assembly based on the comparing the well data to the experience data, wherein the drilling tool assembly is developed using the artificial neural network. The suspending device is formed of a frame arranged between the flue gas channel and the separator in connection with an upper circumference of the wall of the separator, and hanger rods or wires connecting the frame directly to the supporting structure. A driving circuit drives a switching transistor according to the pulse modulation signal SPM. Retaining through holes are defined in the holder plate, slidably retaining the ferrules. This time-series of mean values is subsequently analyzed to determine whether the signal is anomalous.