5.25.2 Ontology5.2OntologyOntologyOntology ConstructionConstructionConstructionConstruction andand ModellingandandModellingModellingModelling TechnologyTechnologyTechnologyTechnology
To meet the demands of the mobile information system for the collaborative product
design, an ontology-based description model is proposed to present in order to
manage and deploy the distributed design resources, this research used Protégé by
Stanford University for constructing the ontology, but capturing the concepts and
describing the relations between the concepts is still a difficult problem.
5.2.1 5.2.1
5.2.15.2.1 BuildBuildBuildBuild OWLOWLOWLOWL OntologyOntologyOntologyOntology
With the help from ADMEC members, author used the available documents in the
first iteration of the building phase. A simple class hierarchy was built, but it was
difficult to derive relations, constraints, and axioms from the documents; so after the
document analysis, the focus was switched to the other knowledge sources, such as
Email and Telephone with the Employers of the companies. The resulting ontology
Chapter 5
The
Application of Semantic Web technology into Mobile Collaborative DesignDocument, Product and Requirement. The most general classes are illustrated in Figu
re 5.1 through a screen-shot from Protégé 4.0. (Companies’ detail will be described
in chapter 8)
Figure Figure Figure
Figure 5.15.15.15.1 Top-levelTop-levelTop-levelTop-level classesclassesclassesclasses andandandand relationsrelations withinrelationsrelationswithinwithinwithin ProtProtProtProtééééggggéééé 4444
The resulting ontology contains some major parts, as can be seen in Figure 5.1, the
figure shows a small part of the ontology and some details are hidden to increase
readability. Despite this, the division of the ontology into subject areas can be noted.
For example, under the root class “Product”, “part” is a (ISA) subclass of software,
and “part” has the child-class “bolt”, which denotes the product provided by the
company; and if the user wants to analyse and check bolt quality, they could refer to
Chapter 5
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Application of Semantic Web technology into Mobile Collaborative Design5.2.2 5.2.2
5.2.25.2.2 OntologyOntologyOntologyOntology ModelingModelingModelingModeling usingusing ProtusingusingProtProtProtééééggggéééé 4444
OWL ontologies have similar components to Protégé frame based ontologies. Below
is the descripton of Building OWL Ontology using Protégé 4 for the mobile system.
� OWLOWLOWLOWL ClassesClassesClassesClasses are interpreted as sets that contain individuals in Figure 5.2.
They are described using formal (mathematical) descriptions that state precisely
the requirements for membership of the class. For example, the class “Product”
would contain all the individuals that are product in the domain of interest.
Classes are organised into a superclass-subclass hierarchy, which is also known
as taxonomy. Subclasses specialise their superclasses. For example consider the
classes “Product” and “Bolt”: “Bolt” might be a subclass of “Product” (so
“Product“is the superclass of “Bolt“). That means that all “Bolts“are “Product“;
Chapter 5
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Application of Semantic Web technology into Mobile Collaborative Design C A D C A D C A D C A D FigureChapter 5
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Application of Semantic Web technology into Mobile Collaborative Design� PropertiesPropertiesPropertiesProperties: They are also known as relations in Unified Modelling Language
(UML) and other object oriented notions. For example, the property “Produce”
might link the individual “Bolt Factory” to the individual “Bolt” (“Bolt
Factory” Produce “Bolt”), or the property “Produced_By” might link the
individual “Bolt” to the individual “Bolt Factory”, Properties can have inverses.
Figure 5.3 is the Property of “A_Class_Hex_Bolt_M10”.
Figure Figure Figure
Chapter 5
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Application of Semantic Web technology into Mobile Collaborative Design� Individuals,Individuals,Individuals,Individuals, represent objects in the domain. OWL does not use the Unique
Name Assumption (UNA) that means two different names could actually refer
to the same individual. Figure 5.4 shows a representation of the individuals in
the domain.
Figure Figure Figure
Chapter 5
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Application of Semantic Web technology into Mobile Collaborative Design5.2.3 5.2.3
5.2.35.2.3 OntologyOntologyOntologyOntology ModellingModellingModellingModelling forfor ShaftforforShaftShaftShaft DesignDesignDesignDesign
Based on ADMEC previous parametric design research in SolidWorks [6-8], the
key concept for the new product design model in OWL is presented in the following
way:
� Every concept in SolidWorks is a class. Thus, Cylinder, Keyway, Chamfer are defined as classes.
� Every Class has its instance. Thus, Cylinder has its own instance, for example, in GearBox design, bearing, cover and gear are all the instances of different
classes.
� Every instance has its own property. Such as Base, Precision and Array property.
� Based on the OWL relationship, the system also has four relationships, such as part-of, kind-of, instance-of and attribute-of.
In the ontology modelling design, the author has divided the product into different
components first, then described the classes and properties of each instance, and
created the relations among them together with the domain expert. Below is to show
the ontology utilized in the shaft design of Gearbox by OWL. Figure 5.5 is a shaft
drawing with specific dimensions to be decided.
Figure Figure Figure
Chapter 5
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Application of Semantic Web technology into Mobile Collaborative DesignThe shaft has the following classes, properties and instances:
� Base Classes: Cylinder, Keyway, Chamfer and Fillet.
� Instance: the instance of the Classes, for example, the longest cylinder is the instance of object Cylinder.
� Cylinder: has their property, such as length, radius, coordinate. � Keyway: has their property, such as length, coordinate.
� Fillet: has their property, such as length, coordinate. � Chamfer: has their property, such as radius, coordinate.
� Base Property: Base coordinate, the keyway centre line and the cylinder centre line.
(Steps of CAD drawing) Established the base coordinate system for the Shaft; took
the centre cylinder base frame as a basic coordinate, built the partial coordinate
system, which had the relations with each other. Figure 5.6 is the ontology model of
the shaft in OWL.
C hamfer R adius: flo at C oordinate : instance F illet R adius : flo at C oordinate : instance Precision attribute R adius : flo at C oordinate : instance B ase attribute C oordinate =0.0 0 .0 C ylinder R adius: flo at C oordinate : instance H eight: flo at F ilet R adius: flo at C oordinate : instance C hamfer R adius : flo at C oordinate : instance Longest clylinder R adius : flo at C oordinate : instance Second cylinder R adius : flo at C oordinate : instance Third cylinder R adius : flo at C oordinate : instance K eyw ay R adius: flo at C oordinate : instance W id th : flo at L en g th : flo at A ttribute of Instance of Instance of Instance of A ttribute of Part of Figure Figure
Chapter 5
The
Application of Semantic Web technology into Mobile Collaborative DesignAfter mobile system builded OWL Ontology using Protégé 4; Semantic Similarity
method will be used to rank the search result and Jena could provide services for
model representation, parsing, database persistence, querying and some
visualization.