Parameter Concept

Within ChemConnect, parameter specifications (ParameterSpecification object) and parameters (ParameterValue object) are important descriptors in the knowledge base. Parameter specifications are can be used, for example, in specifying a complete observation (ObservationSpecification object) which defines the set of (matrix) data that makes up a complete observation. Parameter values are used, for example, to specify the list of attributes describing a catalog object. ParameterValue has as a super class ParameterSpecification. Parameter values have not only the specification, but also the value and uncertainty value associated with the particular instance.

ParameterSpecification in a Catalog object

A ObservationSpecification contains a set of ParameterSpecification concepts to define the list of individual parameters needed to make up a complete observation. This set of specifications can be though of as characterizing each column of a matrix. The matrix itself is a representation of a specific observation.

For example, the time versus pressure observation is a two column matrix. The ObservationSpecification of this observation specifies two ParameterSpecification concepts, one for the time and one for the pressure.

ParameterValue in a catalog object

A ParameterValue is used when a specific attribute of an object needs to be defined. For example, attributes describe a device, subsystem, device component or sensor (SubSystemDescription object).

ParameterSpecification Concept Properties

The ParameterSpecification contains the information needed to describe a parameter (apart from the actual value of the parameter). In ChemConnect, the properties (owl:onProperty) associated with the parameter specification concept are:

• elementType: This defines the type of parameter that is being
• hasPurpose: A concept keyword that represent the purpose of the parameter.
• concept: A concept keyword given an adding context to the parameter, beyond the position within the hierarchy of the parameter.
• unitSystem: The unit class of the parameter.

ParameterValue Concept Properties

The ParameterValue has three parts (using dcterms:hasPart) pointing to three concepts:

• ParameterSpecification: The specification of the parameter.
• ValueAsString: This is the value of the parameter (in the specified units as defined by the specification)
• ValueUncertainty: This is the uncertainty. The actual value used depends on the uncertainty type defined in the specification.

elementType

There are two element types that determine the naming of the parameter:

• FixedParameter: The name of the parameter is standardized being the name of the concept. For example, when the parameter is a column in a data matrix, the standardized name of the parameter is the concept name.
• DynamicParameter: This represents a class of parameters, where the naming is dynamic, meaning it is determined by the data at input. A typical dynamic parameter is species related information, the name

hasPurpose

concept

unitSystem