Integrated generic resource: Material and other engineering properties ISO 10303-45:2008(E)
© ISO

Cover page
Table of contents
Copyright
Foreword
Introduction
1 Scope
2 Normative references
3 Terms, definitions and abbreviations

4 Material property definition
   4.1 Introduction
   4.2 Fundamental concepts and assumptions
   4.3 Material property definition type definitions
   4.4 Material property definition entity definitions
   4.5 Material property definition function definitions
5 Material property representation
   5.1 Introduction
   5.2 Fundamental concepts and assumptions
   5.3 Material property representation entity definitions
6 Qualified measure
   6.1 Introduction
   6.2 Fundamental concepts and assumptions
   6.3 Qualified measure type definition
   6.4 Qualified measure entity definitions

A Short names of entities
B Information object registration
C Computer interpretable listings
D EXPRESS-G diagrams
E Technical discussion
Bibliography
Index

6 Qualified measure schema

The following Express declaration begins the qualified_measure_schema and identifies the necessary external references.

EXPRESS specification:

*)
SCHEMA qualified_measure_schema;

REFERENCE FROM mathematical_functions_schema    --  ISO 10303-50
  (maths_value);

REFERENCE FROM measure_schema    --  ISO 10303-41
  (measure_with_unit,
   unit);

REFERENCE FROM representation_schema    --  ISO 10303-43
  (representation_item);

REFERENCE FROM support_resource_schema    --  ISO 10303-41
  (label,
   text,
   bag_to_set);
(*

NOTE 1   The schemas referenced above are specified in the following part of ISO 10303:

mathematical_functions_schema ISO 10303-50
measure_schema ISO 10303-41
representation_schema ISO 10303-43
support_resource_schema ISO 10303-41

NOTE 2   See Annex D for a graphical representation of this schema.

6.1 Introduction

The qualified_measure_schema specializes the resource constructs from the measure_schema and the maths_function_schema to allow quantities to be qualified, i.e. further characterized as to their type, precision, uncertainty and reliability.

6.2 Fundamental concepts and assumptions

A physical quantity may have several aspects other than its value and units. The value may be uncertain because of the variability in the measurement procedure, leading to a lack of reproducibility. The value of a datum may be labelled as being approved for design, for example, or otherwise characterized as to its type and status. This schema supports the addition of these concepts.

The concept of uncertainty on a measured value used in this part of ISO 10303 is taken from Clause 2.2 of ISO/IEC Guide 98-3:2008. In general, the result of a measurement, y, is only an approximation or estimate of the value of the specific quantity that is the subject of the measurement (the measurand), Y. The uncertainty of the result of a measurement reflects the lack of exact knowledge of the measurand and thus the result is complete only when accompanied by a quantitative statement of its uncertainty. The uncertainty generally consists of several components which may be grouped into two categories according to the method used to estimate the numerical values of the components:

Each component of uncertainty that contributes to the uncertainty of a measurement result is represented by an estimated standard deviation, termed standard uncertainty, ui, and equal to the positive square root of the estimated variance. The procedures for evaluating the standard uncertainty for both of the above categories are described in Clause 4 of ISO/IEC Guide 98-3:2008.

The standard uncertainty of the results of a measurement, when that result is obtained from the values of a number of other quantities, is termed the combined standard uncertainty, uc. It is the estimated standard deviation associated with the result and is equal to the positive square root of the combined variance, obtained by summing all variance and covariance components, however evaluated. The procedure for combining the variance and covariance components is described in Clause 5 of ISO/IEC Guide 98-3:2008. This schema provides the means for representing either the standard uncertainty or the combined standard uncertainty.

NOTE    The number of measurements that have been used to derive the uncertainty of a measured value can be specified by use of the data_environment associated with the value (See Clause 5).

Although the combined standard uncertainty is used to express the uncertainty of many measurement results, what is often required is a measure of uncertainty that defines an interval about the measurement result within which the value of the measurand can be confidently asserted to lie. The measure of uncertainty intended to meet this requirement is termed the expanded uncertainty, U, and is obtained by multiplying uc(y) by a coverage factor, k. Thus U = kuc(y) and it can be confidently asserted that: y – U <=Y <= y + U, which is usually written as Y = y ± U. In general, the value of k is chosen on the basis of the desired level of confidence to be associated with the interval defined by U = kuc. Typically, k is in the range of 2 to 3. When the normal distribution applies to the results and uc has a negligible uncertainty, then k = 2 defines an interval having a level of confidence of approximately 95 percent and k = 3 defines an interval having a level of confidence greater than 99 percent.

6.3 qualified_measure_schema type definition

6.3.1 value_qualifier   EXPRESS-G

The value_qualifier type is a list of alternate data types. It provides a mechanism to refer to an instance of one of these data types.

EXPRESS specification:

*)
TYPE value_qualifier = SELECT
   (precision_qualifier,
    type_qualifier,
    uncertainty_qualifier);
END_TYPE;
(*

6.4 qualified_measure_schema entity definition

6.4.1 descriptive_representation_item   EXPRESS-G

A descriptive_representation_item is a type of representation_item. A descriptive_representation_item is a text element of product data that participates in one or more representations or contributes to the definition of another representation_item.

A descriptive_representation_item contributes to the definition of another representation_item when it is either paired with another representation_item in a representation that has only two representation_items or when the representation that contains a descriptive_representation_item is related to another representation through a representation_relationship.

EXPRESS specification:

*)
ENTITY descriptive_representation_item
  SUBTYPE OF (representation_item);
  description : text;
END_ENTITY;
(*

Attribute definitions:

description: the value of the representation in textual form.

6.4.2 expanded_uncertainty   EXPRESS-G

An expanded_uncertainty is a type of standard_uncertainty. An expanded_uncertainty specifies the coverage factor of an uncertainty.

EXPRESS specification:

*)
ENTITY expanded_uncertainty
  SUBTYPE OF (standard_uncertainty);
  coverage_factor : REAL;
END_ENTITY;
(*

Attribute definitions:

coverage_factor: the multiplier of the uncertainty of the value.

6.4.3 maths_value_qualification   EXPRESS-G

A maths_value_qualification is an association of one or more qualifiers with a maths_value_with_unit.

EXPRESS specification:

*)
ENTITY maths_value_qualification;
  name : label;
  description : text;
  qualified_maths_value : maths_value_with_unit;
  qualifiers : SET[1:?] OF value_qualifier;
WHERE
  WR1: SIZEOF(QUERY(temp <* qualifiers | 'QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp))) < 2;
  WR2: NOT ('REPRESENTATION_SCHEMA.REPRESENTATION_ITEM' IN TYPEOF(SELF\maths_value_qualification.qualified_maths_value));
END_ENTITY;
(*

Attribute definitions:

name: the word or group of words by which the maths_value_qualification is referred to.

description: a narrative description of the maths_value_qualification.

qualified_maths_value: the maths_value_with_unit that is to be qualified.

qualifiers: the further characterisation of the maths_value_with_unit.

Formal propositions:

WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier.

WR2: The entity shall not be used to associate qualifiers with a measure that is used in a complex entity instantiation along with a representation_item.

6.4.4 maths_value_representation_item   EXPRESS-G

A maths_value_representation_item is a type of representation_item and maths_value_with_unit where a particular mathematical function is represented.

EXPRESS specification:

*)
ENTITY maths_value_representation_item
  SUBTYPE OF (representation_item, maths_value_with_unit);
END_ENTITY;
(*

6.4.5 maths_value_with_unit   EXPRESS-G

A maths_value_with_unit is a quantitative value to be specified by mathematical function and to have the unit defined.

EXPRESS specification:

*)
ENTITY maths_value_with_unit;
  value_component : maths_value;
  unit_component : unit;
END_ENTITY;
(*

Attribute definitions:

value_component: the reference to the specification of the mathematical function.

unit_component: the reference to the unit quantity for the value_component.

6.4.6 measure_qualification   EXPRESS-G

A measure_qualification is an association of one or more qualifiers with a measure_with_unit.

EXPRESS specification:

*)
ENTITY measure_qualification;
  name : label;
  description : text;
  qualified_measure : measure_with_unit;
  qualifiers : SET[1:?] OF value_qualifier;
WHERE
  WR1: SIZEOF(QUERY(temp <* qualifiers | 'QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp))) < 2;
  WR2: NOT ('REPRESENTATION_SCHEMA.REPRESENTATION_ITEM' IN TYPEOF(SELF\measure_qualification.qualified_measure));
END_ENTITY;
(*

Attribute definitions:

name: the word or group of words by which the measure_qualification is referred to.

description: a narrative description of the measure_qualification.

qualified_measure: the measure_with_unit that is to be qualified.

qualifiers: the further characterization of the measure_with_unit.

Formal propositions:

WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier.

WR2: The entity shall not be used to associate qualifiers with a measure that is used in a complex entity instantiation along with a representation_item.

6.4.7 measure_representation_item   EXPRESS-G

A measure_representation_item is a type of representation_item and measure_with_unit where a particular numerical value and its unit is represented.

EXPRESS specification:

*)
ENTITY measure_representation_item
  SUBTYPE OF (representation_item, measure_with_unit);
END_ENTITY;
(*

6.4.8 precision_qualifier   EXPRESS-G

A precision_qualifier is the number of significant figures in the representation of a value.

EXPRESS specification:

*)
ENTITY precision_qualifier;
  precision_value : INTEGER;
END_ENTITY;
(*

Attribute definitions:

precision_value: the number of significant figures of the value.

6.4.9 qualified_representation_item   EXPRESS-G

A qualified_representation_item is a type of representation_item for which qualifiers are defined to describe its reliability and/or uncertainty.

EXPRESS specification:

*)
ENTITY qualified_representation_item
  SUBTYPE OF (representation_item);
  qualifiers : SET[1:?] OF value_qualifier;
WHERE
  WR1: SIZEOF(QUERY(temp <* qualifiers | 'QUALIFIED_MEASURE_SCHEMA.PRECISION_QUALIFIER' IN TYPEOF(temp))) < 2;
END_ENTITY;
(*

Attribute definitions:

qualifiers: the further characterization of the representation_item.

Formal propositions:

WR1: At most one of the elements of the qualifiers attribute can be a precision_qualifier.

6.4.10 qualitative_uncertainty   EXPRESS-G

A qualitative_uncertainty is a type of uncertainty_qualifier. A qualitative_uncertainty specifies the uncertainty of a value by comparison.

EXPRESS specification:

*)
ENTITY qualitative_uncertainty
  SUBTYPE OF (uncertainty_qualifier);
  uncertainty_value : text;
END_ENTITY;
(*

Attribute definitions:

uncertainty_value: the qualitative uncertainty of the value.

EXAMPLE    Expected values for uncertainty_value include: 'low', 'medium', 'high'.

6.4.11 standard_uncertainty   EXPRESS-G

A standard_uncertainty is a type of uncertainty_qualifier. A standard_uncertainty may be an expanded_uncertainty.

EXPRESS specification:

*)
ENTITY standard_uncertainty
  SUPERTYPE OF (expanded_uncertainty)
  SUBTYPE OF (uncertainty_qualifier);
  uncertainty_value : REAL;
END_ENTITY;
(*

Attribute definitions:

uncertainty_value: the quantitative uncertainty of the value.

6.4.12 type_qualifier   EXPRESS-G

A type_qualifier is the specification of a type of a datum.

NOTE    Legal values and constraints for the attribute are specified in application protocols. Typical values for the attribute may include: 'measured', 'calculated', 'nominal', 'maximum', 'minimum', 'theoretical', 'remainder', 'design-allowable', 'combined', 'A-basis statistical', 'B-basis statistical' and 'arithmetic mean'.

EXPRESS specification:

*)
ENTITY type_qualifier;
  name : label;
END_ENTITY;
(*

Attribute definitions:

name: the word or group of words by which the type or reliability of the value is referred to.

6.4.13 uncertainty_qualifier   EXPRESS-G

A uncertainty_qualifier is the uncertainty of a value. A uncertainty_qualifier may be either a standard_uncertainty or a qualitative_uncertainty.

EXPRESS specification:

*)
ENTITY uncertainty_qualifier
  SUPERTYPE OF (ONEOF (standard_uncertainty,
                       qualitative_uncertainty));
  measure_name : label;
  description : text;
END_ENTITY;
(*

Attribute definitions:

measure_name: specifies the kind of measure for which the entity defines the uncertainty.

EXAMPLE    Expected values for measure_name include: 'distance uncertainty', 'angular uncertainty', 'curvature uncertainty'.

description: the description of the uncertainty of the value.



*)
END_SCHEMA;  -- qualified_measure_schema
(*


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