Template:— conditional_availability (cnd_avl)
Context:— UK_Defence

Date: 2010/03/18 14:17:12
Revision: 1.9

Cover Contents Description Bus. obj.Model diags.Input params.Ref. params.Instantiation path Instance diags.Characterizations Issues in situ

This section specifies the template conditional_availability.

NOTE The template has been defined in the context of UK_Defence. Refer to the business context for details of related templates.

NOTE An explanation of a template and the associated instantiation path is provided in the Template overview section.

Description

This template describes how to represent the availability requirements for a PSE constituent within a defined role.

Business object definition

The definition of Conditional Availability is part of the definition of a required_pse_constituent_usage_role object, in that it is used to represent; achieved availability, inherent availability and operational availability. The availability is represented as a property (probability) under one of the conditions provided.

Conditional Availability is not an object, in its own right, but provides the the functionality of several attributes required as part of the required_pse_constituent_usage_role object. The figure below is provided for reference purposes only.

Figure 1 — Graphical Representation for Conditional Availability taken from the Business Object required_pse_constituent_usage_role.

The attributes of the Conditional Availability requirements are tabled below.

Attribute name	Attribute description	Attribute type	Optionality
Availability Context	This is the description of the context for which the availability is defined.	Relationship to required_pse_constituent_usage_role	Mandatory
Availability Type	This is the type of availability; e.g Achieved, Inherent, Operational.	intrinsic	Mandatory
Availability Condition	This is the CLASS that describes the required probability that the item will operate satisfactorily when required. E.g. 'Under nominal conditions'.	intrinsic	Mandatory
Availability Value	This is the probability that the condition will occur.	Numeric	Mandatory

Table 1 — Conditional Availability requirement details

Model diagrams

The EXPRESS-G diagram in Figure 2 shows the templates and EXPRESS entities that are required to represent the template "conditional_availability". The text highlighted in blue shows the template parameters.

Figure 2 — An EXPRESS-G representation of the Information model for conditional_availability

The graphic for the template to be used in other EXPRESS-G diagrams is shown in Figure 3 below.

Figure 3 — The graphical representation of the conditional_availability template

Input parameters

The following input parameters are defined for this template:

availability_context (Type= 'ENTITY (Task_method_version)' )

The context in which the availability is defined.

availability_type (Type='CLASS')

This is the required probability that the item will operate satisfactorily when required.

The following classes and their sub-classes can be used:

classifications: [achieved]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml
[inherent]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml
[operational]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml

availability_condition (Type='CLASS')

This is the required probability that the item will operate satisfactorily when required.

The following classes and their sub-classes can be used:

classifications: [under_nominal_conditions]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml
[with_all_required_resources]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml
[including_standby_and_preventive_maintenance_downtime]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml
[excluding_downtime_due_to_supply_and_administration]

Error RDL4: The URI urn:plcs:rdl:uk_defence is not listed in dexlib/data/refdata/rdl_index.xml

availability_value (Type= 'TYPE (any_number_value)' )

This is the probability that the condition will occur. NOTE: The value represents the analyst's judgement as to the conditional probability that the loss will occur, and is quantified in general accordance with the following Availability Values;

Actual: 1.00
Probable: 0.10 to 1.00
Possible: 0.00 to 0.10
None: 0.00

Reference parameters

The following reference parameters are defined for this template:

conditional_availability(Type='ENTITY (Condition)')

Allow the Condition entity instantiated in this path to be referenced when this template is used.

Note: The Condition entity can be referenced in a template path by:

%^target = $conditional_availability.conditional_availability%

where target is the parameter to which the Condition is bound.

property(Type='ENTITY (Assigned_property)')

Allow the Assigned_property entity instantiated in this path to be referenced when this template is used.

Note: The Assigned_property entity can be referenced in a template path by:

%^target = $conditional_availability.property%

where target is the parameter to which the Assigned_property is bound.

Instantiation path

The instantiation path shown below specifies the entities that are to be instantiated by the template.

A description of templates and the syntax for the instantiation path is provided in the Templates Help/Information section.

-- availability_value
/assigning_product_property(
    described_element=@availability_context,
    property_class_name='Normalized_numeric_probability',
    property_ecl_id='urn:plcs:rdl:std')/

-- assign ref parameters
%^property = $assigning_product_property.property%

-- Probability numeric value
/product_property_numeric(
    value=@availability_value,
    unit='Probability_numeric',
    unit_ecl_id='urn:plcs:rdl:std',
    si_unit='.F.',
    context='Numerical_representation_context',
    context_ecl_id='urn:plcs:rdl:std',
    property=^property)/

-- availability_type
/assigning_reference_data(
    items=^property,
    class_name=@availability_type,
    ecl_id='urn:plcs:rdl:UK_Defence')/

-- create condition
%^condition = Condition%
^condition.name = '/IGNORE'
Condition_assignment
Condition_assignment.assigned_condition -> ^condition
Condition_assignment.item -> ^property

-- availability_condition
/assigning_reference_data(
    items=^condition,
    class_name=@availability_condition,
    ecl_id='urn:plcs:rdl:UK_Defence')/

The following entities are instantiated with attributes as specified:

Entity in path	Value	Inherited from
Condition.name	'/IGNORE'	—

Instance diagrams

The instance diagram in Figure 4 shows an example of the EXPRESS entities and templates that are instantiated by the template:

/conditional_availability(availability_context='@84', availability_type='operational', availability_condition='under_nominal_conditions', availability_value='ANY_NUMBER_VALUE(0.75)')/

(an illustration of the consolidated conditional_availability template is shown in Figure 5 below.)

Figure 4 — Entities instantiated by conditional_availability template

The instance diagram in Figure 5 shows the graphic symbol for the template that is to be used in other instance diagrams. The example template is:

/conditional_availability(availability_context='@84', availability_type='operational', availability_condition='under_nominal_conditions', availability_value='ANY_NUMBER_VALUE(0.75)')/

Figure 5 — Instantiation of conditional_availability template

Characterizations

No common characterizations of the template conditional_availability have been identified. However, the ISO 10303-239 EXPRESS model may enable other assignments to the entities instantiated by the template.