other issues that should be considered in the life-cycle cost analysis and evaluation of millimeter-wavelength/terahertz imaging systems:

  • Installation—time, footprint, and skill requirements for installation personnel;

  • Integration—interconnectivity and interoperability implementation costs;

  • Reliability—expected lifetime before replacement, MTBF (mean time before failure) statistics, and unscheduled downtime costs;

  • Scheduled downtime—calibration or scheduled maintenance costs;

  • Repairs—MTTR (mean time to repair) statistics, availability of repair parts, warranty, onsite or offsite, and skill requirements;

  • Environmental—Occupational Safety and Health Administration requirements; and

  • Training—initial and update training, operator skill-level requirements.

A valid life-cycle cost analysis needs sound data input. These data (1) can be developed using widely acceptable reliability predictor models, or (2) be gathered from operations of similar systems and complete logs maintained during the pilot demonstration phase of system deployment. Industrial experience has shown that initial cost may comprise only 10 to 15 percent of the total cost.5


J.T. Bailey and S.R. Heidt. 2003. Why Is Total Cost of Ownership (TCO) Important? If You Want to Know Where Your Money Goes, Get Ready to Master the Concept of TCO. Available at http://www.darwinmag.com/read/110103/question74.html. Accessed August 28, 2006.

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