Bench test model of the human skull for testing the Variable Frequency Pulse Phase-Locked Loop Instrument
By:  Amy Diana Burin
Publisher: Naval Postgraduate School; Available from National Technical Information Service
Published: 1996
Place of publication: Monterey, Calif; Springfield, Va
Language: eng
Number of pages: 118
Description: The Variable Frequency Pulse Phase-Locked Loop (VFPPLL) instrument is currently being      used to non-invasively evaluate the human skull for increases in intracranial distances brought      about by increases in intracranial pressure. It is designed to determine distance changes, in the      sub-micron range, calculated from changes in frequency of an ultrasonic toneburst produced      by a transducer, traversed through the skull and received back by the transducer. A bench test      model of the human skull will calibrate the VFPPLL by comparing known distance changes to      the VFPPLL derived distance changes, and thereby verify the accuracy of the instrument.      Additionally, the bench test model will determine a broad range of operating limits on      temperature, pressure and elongation over which the VFPPLL can operate accurately. Each      of the three models made demonstrates a different effect on the frequency change based on      the different parameters, i.e. temperature, pressure or elongation. The Open Channel Model      compares closely approximated elongations with VFPPLL derived elongations, showing      favorable results for calibration of the VFPPLL instrument. Specifications for creating a bench      test model of the human skull for testing the VFPPLL instrument are established in this thesis.
Notes: Thesis advisor(s): Sandra L. Scrivener.

"December 1996."

Thesis (M.S. in Astronautical Engineering) Naval Postgraduate School, December 1996.

Includes bibliographical references (p. 115-116).

Approved for public release; distribution unlimited.

Also available online.

Mode of access: World Wide Web.

System requirements: Adobe Acrobat Reader.

US Navy (USN) author.

dk/dk cc:9116 6/11/97.