Abstract: An energy harvesting circuit is disclosed and comprises one or more electrical loads that consume direct current (DC) power, a rectifier, and a hybrid acoustic absorber. The rectifier comprises one or more active switching elements that are driven by a gate drive voltage. The hybrid acoustic absorber comprises a diaphragm and a voice coil. The diaphragm is constructed at least in part of a piezoelectric material. The piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm. The diaphragm voltage is at least equal to the gate drive voltage to drive the one or more active switching elements of the rectifier. The voice coil is attached to the diaphragm and configured to generate a voice coil voltage that is less than the gate drive voltage of the one or more active switching elements.

Abstract: A testing system for monitoring a machine under test is disclosed and includes one or more high frequency sensors configured to generate a sensor signal that is representative of an operating parameter of the machine. The high frequency sensors have a required high frequency sampling rate. The testing system also includes a notification device configured to generate a notification indicating the operating parameter monitored by the high frequency sensors has exceeded a predefined threshold value and a data acquisition control module configured to monitor the high frequency sensors at a first sampling rate. The testing system also includes a monitoring control module in electronic communication with the notification device. The monitoring control module is configured to monitor the high frequency sensors at a second sampling rate that is greater than the first sampling rate and at least equal to the required high frequency sampling rate.

Abstract: An energy harvesting circuit is disclosed and comprises one or more electrical loads that consume direct current (DC) power, a rectifier, and a hybrid acoustic absorber. The rectifier comprises one or more active switching elements that are driven by a gate drive voltage. The hybrid acoustic absorber comprises a diaphragm and a voice coil. The diaphragm is constructed at least in part of a piezoelectric material. The piezoelectric material is configured to generate a diaphragm voltage in response to sound waves deforming the diaphragm. The diaphragm voltage is at least equal to the gate drive voltage to drive the one or more active switching elements of the rectifier. The voice coil is attached to the diaphragm and configured to generate a voice coil voltage that is less than the gate drive voltage of the one or more active switching elements.

Abstract: A testing system for monitoring a machine under test is disclosed and includes one or more high frequency sensors configured to generate a sensor signal that is representative of an operating parameter of the machine. The high frequency sensors have a required high frequency sampling rate. The testing system also includes a notification device configured to generate a notification indicating the operating parameter monitored by the high frequency sensors has exceeded a predefined threshold value and a data acquisition control module configured to monitor the high frequency sensors at a first sampling rate. The testing system also includes a monitoring control module in electronic communication with the notification device. The monitoring control module is configured to monitor the high frequency sensors at a second sampling rate that is greater than the first sampling rate and at least equal to the required high frequency sampling rate.