Xu, Yuanping (2009) The exploration of a category theory-based virtual Geometrical product specification system for design and manufacturing. Doctoral thesis, University of Huddersfield.

In order to ensure quality of products and to facilitate global outsourcing, almost all
the so-called “world-class” manufacturing companies nowadays are applying various
tools and methods to maintain the consistency of a product’s characteristics
throughout its manufacturing life cycle. Among these, for ensuring the consistency of
the geometric characteristics, a tolerancing language − the Geometrical Product
Specification (GPS) has been widely adopted to precisely transform the functional
requirements from customers into manufactured workpieces expressed as tolerance
notes in technical drawings. Although commonly acknowledged by industrial users as
one of the most successful efforts in integrating existing manufacturing life-cycle
standards, current GPS implementations and software packages suffer from several
drawbacks in their practical use, possibly the most significant, the difficulties in
inferring the data for the “best” solutions. The problem stemmed from the foundation
of data structures and knowledge-based system design. This indicates that there need
to be a “new” software system to facilitate GPS applications.
The presented thesis introduced an innovative knowledge-based system − the
VirtualGPS − that provides an integrated GPS knowledge platform based on a stable
and efficient database structure with knowledge generation and accessing facilities.
The system focuses on solving the intrinsic product design and production problems
by acting as a virtual domain expert through translating GPS standards and rules into
the forms of computerized expert advices and warnings. Furthermore, this system can
be used as a training tool for young and new engineers to understand the huge amount
of GPS standards in a relative “quicker” manner.
The thesis started with a detailed discussion of the proposed categorical modelling
mechanism, which has been devised based on the Category Theory. It provided a
unified mechanism for knowledge acquisition and representation, knowledge-based
system design, and database schema modelling. As a core part for assessing this
knowledge-based system, the implementation of the categorical Database
Management System (DBMS) is also presented in this thesis. The focus then moved
on to demonstrate the design and implementation of the proposed VirtualGPS system.
The tests and evaluations of this system were illustrated in Chapter 6. Finally, the
thesis summarized the contributions to knowledge in Chapter 7.
After thoroughly reviewing the project, the conclusions reached construe that the
entire VirtualGPS system was designed and implemented to conform to Category
Theory and object-oriented programming rules. The initial tests and performance
analyses show that the system facilitates the geometric product manufacturing
operations and benefits the manufacturers and engineers alike from function designs,
to a manufacturing and verification.

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