  We examine the problem of weaknesses in frameworks of conceptual modeling for
handling certain aspects of the system being modeled. We propose the use of a
flow-based modeling methodology at the conceptual level. Specifically, and
without loss of generality, we develop a conceptual description that can be
used for controlling the maintenance of a physical system, and demonstrate it
by applying it to an existing electrical power plant system. Recent studies
reveal difficulties in finding comprehensive answers for monitoring operations
and identifying risks as well as the fact that incomplete information can
easily lead to incorrect maintenance. A unified framework for integrated
conceptualization is therefore needed. The conceptual modeling approach
integrates maintenance operations into a total system comprising humans,
physical objects, and information. The proposed model is constructed of
(abstract) machines of things connected by flows, forming an integrated whole.
It represents a man-made, intentionally constructed system and includes
technical and human things observable in the real world, exemplified by the
study case described in this paper. A specification is constructed from a
maximum of five basic operations: creation, processing, releasing,
transferring, and receiving.
