Sanwu received a MSME (1991) and a BSME (1987) degree from Xi'an Jiaotong University, one of the top 5 universities of China in engineering. He worked as a mechanical engineer for 8 years in China (structure design, finite element analysis, vibration test and modal analysis). In 1985, he won the first-prize of Advanced Mathematics Competition of Universities in Shaanxi State. In 1983, he won the first-prize of National Mathematics Competition of China.
In 1995, Sanwu started his PHD program at UCSD.In 1997, he had a summer job at Quantum Corp. (Shrewsbury, MA) and gained experience with the DLT tape drive. Now, he is working on the magnetic head/media interface at the Center for Magnetic Recording and Research at UCSD. Sanwu passed his Candidacy Exam in 1998. He will finish his PHD at the end of 1999.
Recent Publications:
Abstract--A new tape looper has been installed at CMRR which is capable of working with 1/4", 1/2", 3/4" and 8 mm tape. The tape speed, tape tension and tape wrap angle is controlled by a PC. Various tape heads and metal particle tapes are used for recording experiments. Mechanical and magnetic calibration of the system has been done and initial study show good agreement between mechanical surface roughness correlation length and magnetic correlation length. Future work includes in-depth analysis of correlation between tape surface roughness and medium noise, and comparison of the head/tape spacing from both mechanical and magnetic measurements, etc.
Abstract-- The nano- and macro-wear characteristics of calcium titanate, single crystal and polycrystalline Mn-Zn ferrite was investigated using nano-scrath and wear tests. The microstructure of test specimens was analyzed using Scanning Electron Microscope and X-ray diffraction. Nano-indentations were made to determine the nano-hardness. Nano-scratch tests were used to evaluate relative nano-wear rates. The macro-wear characteristics of the head materials was investigated using wear bars mounted in a DLT tape drive. A simplified method was used to calculate the wear volume. Different metal particle tapes and different tape speeds were used in the wear bar tests. The methods for nano- and macro-wear test were analyzed and the results were compared. Micro-indentation method was also applied for measuring wear of a DLT tape head.
Abstract--Head/tape spacing and asperity compliance of magnetic tapes are measured using three-color interferometry. The contact spacing obtained from asperity compliance measurements are found to correlate with the head/tape spacing very well and can be used to estimate the isolated asperity limited head/tape spacing. The local surface roughness measured by AFM does not correlate with the head/tape spacing very well due to the ignorance of the long wavelength isolated asperities.
Abstract--The spacing of the head/tape interface in a digital linear tape (DLT) drive was measured using replica glass heads and three-color interferometry. A modified load-unload method was used to calibrate the light intensity. Glass heads with different island widths and zero and nine-degree skew angles were used to investigate the effect of head contour on the head/tape spacing. In addition, thin and thick metal particle tapes were evaluated to study the effect of tape compliance, tape speed and tape tension. "Tape tenting" was observed for heads with a narrow center island.
Abstract--Three-color interferometry was used to investigate the deformation of asperities on flexible medium surfaces. Elastic asperity compliance curves were obtained to evaluate changes in surface roughness due to burnishing, determine mechanical properties of flexible medium and analyze differences between single layer and dual layer metal particle tapes. Asperity compliance curves were obtained for metal particle tapes with different substrate properties and substrate thickness. A power function was used to fit the asperity compliance measurements and to calculate the contact pressure at the head/medium interface.
Last updated: July 1, 1999
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