The translation of element attributes and attributes with classifications will be illustrated with ‘igntionType’
The element ignition type has 4 attributes, target, type, amount and units. These will be translated to the ontology ‘IgnitonType‘ class object using the ‘has property’ predicate as illustrated previously. The M and O are denoted in the annotation of each of these attribute properties (within the yellow ‘@’ as illustrated before).
The ‘target’ has somewhat of a required format as outlined in the description:
These are to be denoted by “p”, “T”, and the name of the species (e.g. OH), respectively. If the ignition delay is defined based on multiple physical properties, e.g., the product of the CO and O2 mole fractions, the target attribute should contain all names separated by semicolons.
However, at the moment, this is not reflected in the ontology. The attribute is free text.
In the attributes, a mandatory ignition ‘type‘ is given. The valid ‘type‘ values are given in a table in the specification. This is represented in a ‘classification’ object in the ontology (RespecthAttributeIgnitionType). The subclasses of this object are the valid types, one ontology object for each of the valid types. The label and the comments are transcribed from the table (see example for ‘d/dt max). Which of these valid ‘type’ values determine how the ‘amount’ and ‘units’ are treated. This results in three subclasses of ‘ignitionType’ (see below).
In the following explanation, it might be a bit confusing because ‘ignition type’ is actually used in three different contexts: as an element definition (‘ignitionType’), as an attribute definition (‘type’) and finally as the possible choices for the value of the ‘type’ attribute.
The valid ignition types from the specification are translated to a classification hierarchy in the ontology.
Amount and Ignition Type
Reading the description of ‘amount’ in the specification, it can be seen that there are three catagories of valid ignition types. These are reflected in the subclasses of ‘RespecthValidIgnitionTypes‘. Two categories deal with concentrations: those with absolute concentration (‘concentration type (absolute)’) and those with relative concentration (concentration type (relative)). The rest are in the category ‘Valid ignition type (non-concentration).
These three catagories mark the three classes of ‘Ignition Type’ (the ‘ignitionType’ element). Each of these point to their respective ‘RespecthValidIgnitionTypes’. So though there is only one attribute, ‘type’, in the specification, in the translation this ‘type’ is divided into three different attributes, each having different properties. It can be said that the single attribute ‘type’ in the specification corresponds to the ‘Ignition Type’ class which is the parent of the different translations in the ontology.
Thus the attribute points to (‘rdfs:isDefinedby‘) concentration type (relative)’. Note that the identifier is still ‘type’. So though the specification does not make this distinction, the translation to the ontology does. In the specification, this distinction is implicit and buried in the text. In the ontology, the meaning buried in the text is translated to an actionable/searchable entity. The semantic in the text has been translated into an ontology representation.
Relative Concentration/Increase ‘ignitionType’ element
In the top specification of the ignition type element, there are three attributes, ‘units’, amount’ and ‘target’. These are translated into the ontology objects, ‘Property Units’, ‘Amount’ and ‘Target’, respectively.
As explained previously, there are three types of attributes for ‘type’. The text above explains that depending on the type, the ‘amount’ and ‘units’ attributes are handled differently. However, for all three types, the ‘target’ value is the same. In the ontology this is reflected by having ‘Target’ an attribute (‘has property’) of the top class (‘Ignition Type Attribute’) and this is then inherited by each of the subclasses. It is in the subclasses where the treatment of ‘Property Units’ and ‘Amount’ are treated.
The description text above shows that if the type is ‘relative concentration’ or ‘relative increase’ type, then the ‘amount’ is a numerical value which reflects this concentration. In this case the ‘units’ should be ‘unitless’. In the ontology, this is reflected in inheriting the target from its parent class (‘Ignition Type Attribute’) and defining the attributes (‘has property’) for ‘Property Units’ and ‘Amount’. In the annotations of each of these links (the yellow ‘@’) is ‘mandatory’ specification. The ‘Property Units’ annotation has one extra annotation, namely that the ‘default value’ is ‘unitless’.
Absolute Concentration ‘ignitionType’ Element
For the ‘absolute concentration’ type, once again the ‘Target’ is inherited from the parent class and the two other attributes (linked with ‘has property’), ‘Amount’ and ‘Property Units’, are given in the ‘Ignition Type Relative Concentration’ element. Once again the annotation (yellow ‘@’) signifies ‘Mandatory’ for all the attributes. Note that for ‘absolute concentation’ the units are given.
Non-concentration ‘ignitionType’ element
For the ‘Ignition Type (non concentration)’ case, the ‘amount’ and ‘unit’ attributes are not needed. Thus no property link to ‘Amount’ or ‘Property Units’ is specified. However, the ‘Target’ (as with all cases) is inherited from the parent ‘Ignition Type’ class.
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