IfcConversionBasedUnitWithOffset

IfcConversionBasedUnitWithOffset

实体定义
IfcConversionBasedUnitWithOffset是通过应用转换因子和偏移量从另一个单位转换而来的单位。
IFC4中的新实体。
示例：温度单位华氏度基于温度单位开尔文，如下所示：

 

f = k · 1.8 – 459.67

 

其中k是以开尔文表示的绝对温度，f是以华氏度表示的相同温度。以下实体实例将华氏温度作为一个单位：

 

IfcConversionBasedUnitWithOffset(
    IfcDimensionalExponents(0, 0, 0, 0, 1, 0, 0),
    THERMODYNAMICTEMPERATUREUNIT,
    'Fahrenheit',
    IfcMeasureWithUnit(
        IfcThermodynamicTemperatureMeasure(1.8),
        IfcSiUnit(THERMODYNAMICTEMPERATUREUNIT, ?, KELVIN)),
    -459.67);

 

 

Attribute inheritance

#	Attribute	Type	Cardinality	Description	C
IfcNamedUnit
1	Dimensions	IfcDimensionalExponents	[1:1]	The dimensional exponents of the SI base units by which the named unit is defined.	X
2	UnitType	IfcUnitEnum	[1:1]	The type of the unit.	X
IfcConversionBasedUnit
3	Name	IfcLabel	[1:1]	The word, or group of words, by which the conversion based unit is referred to.	X
4	ConversionFactor	IfcMeasureWithUnit	[1:1]	The physical quantity from which the converted unit is derived.	X
	HasExternalReference	IfcExternalReferenceRelationship @RelatedResourceObjects	S[0:?]	Reference to external information, e.g. library, classification, or document information, which is associated with the conversion-based unit.	X
IfcConversionBasedUnitWithOffset
5	ConversionOffset	IfcReal	[1:1]	A positive or negative offset to add after the inherited ConversionFactor was applied.	X

 

 

 

EXPRESS Specification

ENTITY IfcConversionBasedUnitWithOffset
 SUBTYPE OF (IfcConversionBasedUnit);
  ConversionOffset : IfcReal;
END_ENTITY;

 

 

 

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