Molal Concentration Unit
Area Time Temperature Unit
All units about counts. Examples are Atomic Number, Number, Number per Year, Percent and Sample per Second.
Counting Unit
1
Photometry Unit
The linear charge density is the amount of electric charge in a line. It is measured in coulombs per metre (C/m). Since there are positive as well as negative charges, the charge density can take on negative values. [Wikipedia]
Electric Charge Line Density Unit
Respiratory Rate Unit
The symbol for a unit is a glyph that is used to represent the unit in a compact form. For example, the symbol for the US Dollar is $. This contrasts with unit:abbreviation, which gives a short alphanumeric abbreviation for the unit. (I.e. USD for US Dollar).
symbol
type prefix
The canonicall example of extrinsic curvature is that of a circle, which has curvature equal to the inverse of its radius everywhere. Smaller circles bend more sharply, and hence have higher curvature. The curvature of a smooth curve is defined as the curvature of its osculating circle at each point. The osculating circle of a sufficiently smooth plane curve at a given point on the curve is the circle whose center lies on the inner normal line and whose curvature is the same as that of the given curve at that point. This circle is tangent to the curve at the given point.
That is, given a point P on a smooth curve C, the curvature of C at P is defined to be 1/R where R is the radius of the osculating circle of C at P. The magnitude of curvature at points on physical curves can be measured in diopters (also spelled dioptre) — this is the convention in optics. [Wikipedia]
Curvature Unit
In physics, natural units are physical units of measurement based only on universal physical constants. For example the elementary charge e is a natural unit of electric charge, or the speed of light c is a natural unit of speed. A purely natural system of units is defined in such a way that some set of selected universal physical constants are normalized to unity; that is, their numerical values in terms of these units become exactly 1. Examples are Planck Units and Atomic Units. Atomic units (au or a.u.) form a system of natural units which is especially convenient for atomic physics calculations. There are two different kinds of atomic units, which one might name Hartree atomic units[1] and Rydberg atomic units, which differ in the choice of the unit of mass and charge. Planck units are unique among systems of natural units, because they are not defined in terms of properties of any prototype, physical object, or even elementary particle. [Wikipeda]
System of natural units
Length Unit
Power Per Area Unit
A type specification for all units that are not used in the SI standard.
Not Used With SI Unit
A DerivedUnit is a type specification for units that are derived from other units.
Derived Unit
UEM
When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion.
Different coefficients of thermal expansion can be defined for a substance depending on whether the expansion is measured by:
* linear thermal expansion
* area thermal expansion
* volumetric thermal expansion
These characteristics are closely related. The volumetric thermal expansion coefficient can be defined for both liquids and solids. The linear thermal expansion can only be defined for solids, and is common in engineering applications.
Some substances expand when cooled, such as freezing water, so they have negative thermal expansion coefficients.
For exactly isotropic materials, the volumetric thermal expansion coefficient is very closely approximated as three times the linear coefficient. [Wikipedia]
Volume Thermal Expansion Unit
element kind
A unit of measure, or unit, is a particular quantity value that has been chosen as a scale for measuring other quantities the same kind (more generally of equivalent dimension). For example, the meter is a quantity of length that has been rigorously defined and standardized by the BIPM (International Board of Weights and Measures). Any measurement of the length can be expressed as a number multiplied by the unit meter. More formally, the value of a physical quantity Q with respect to a unit (U) is expressed as the scalar multiple of a real number (n) and U, as Q = nU.
Unit
Magnetomotive force is any physical cause that produces magnetic flux. In other words, it is a field of magnetism (measured in tesla) that has area (measured in square meters), so that (Tesla)(Area)= Flux. It is analogous to electromotive force or voltage in electricity. MMF usually describes electric wire coils in a way so scientists can measure or predict the actual force a wire coil can generate. [Wikipedia]
This class contains the following instance(s): "Ampere turn", "Gilbert", "Oersted centimeter", "Unit pole".
Magnetomotive Force Unit
This class contains units of measure for specific heat capacity at a constant volume.
Specific Heat Volume Unit
1024
This property relates a unit system with a unit of measure that is not defined by or part of the system, but is allowed for use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.
allowed unit
Energy and work per mass amount of substance
Radiance Unit
The units of angular mass have dimensions of mass * area. They are used to measure the moment of inertia.
Angular Mass Unit
Physical Unit
conversion coefficient
Computing Unit
Provides a schema for describing Units of Measure
QUDT
Quantities, Units, Dimensions and Types (QUDT) Ontology Version 1.1
David Price
Daniel Mekonnen
http://qudt.org/schema/qudt
$Id: OSG_qudt-(v1.1).ttl 4989 2011-06-01 21:56:40Z RalphHodgson $
2011-01-06T09:30:49
Quantities, Units, Dimensions and Types
All disciplines
Basic treatment of quantities and units. No dimensional treatment in this graph.
Irene Polikoff
1.1
The QUDT, or 'Quantity, Unit, Dimension and Type' collection of ontologies define the base classes properties, and restrictions used for modeling physical quantities, units of measure, and their dimensions in various measurement systems. The goal of the QUDT ontology is to provide a unified model of, measurable quantities, units for measuring different kinds of quantities, the numerical values of quantities in different units of measure and the data structures and data types used to store and manipulate these objects in software. This OWL schema is a foundation for a basic treatment of units.
$LastChangedDate: 2011-06-01 14:56:40 -0700 (Wed, 01 Jun 2011) $
The QUDT Ontologies are issued under a Creative Commons Attribution Share Alike 3.0 United States License. Attribution should be made to NASA Ames Research Center and TopQuadrant, Inc.
Science, Medicine and Engineering
1
qudt
Ralph Hodgson
James E. Masters
Quantities, Units, Dimensions and Types (QUDT) - Level 1
Inverse Amount Of Substance Unit
Thermal Energy Unit
Electrochemistry Unit
100.00
basis element
Temperature per time unit
description
Electric Flux Density Unit
A reference to the unit of measure of a quantity (variable or constant) of interest.
unit
Volume Unit
An abbreviation for a unit is a short (usually 5 characters or less) string that is used in place of the full name for the unit in contexts where space is limited, or where using the abbreviation will enhance readability.
abbreviation
Radiology Unit
100
Molar Heat Capacity Unit
Mass Amount Of Substance Temperature Unit
Units that quantify energy per unit area.
Energy Per Area Unit
A system of units is coherent with respect to a system of quantities and equations if the system of units is chosen in such a way that the equations between numerical values have exactly the same form (including the numerical factors) as the corresponding equations between the quantities. In such a coherent system, no numerical factor other than the number 1 ever occurs in the expressions for the derived units in terms of the base units.
coherent unit system
Length Temperature Time Unit
A Dimensionless Unit is a quantity for which all the exponents of the factors corresponding to the base quantities in its quantity dimension are zero.
Dimensionless Unit
title
The linear, surface, or volume charge density is the amount of electric charge in a line, surface, or volume. It is measured in coulombs per metre (C/m), square metre (C/m^2), or cubic metre (C/m^3), respectively. Since there are positive as well as negative charges, the charge density can take on negative values. [Wikipedia]
Electric Charge Density Unit
The ratio of energy to electric charge arises repeatedly in electrodynamics. It is the dimensional equivalent to the electrostatic potential and electromotive force. In both cases, the SI unit is the volt, or newton meters per coulomb.
Energy per Electric Charge Unit
UB
1
A Non-SI unit. Typically an imperial measure.
Non SI Unit
Current Per Angle Unit
Units that measure energy density, i.e. energy per unit volume.
Energy Density Unit
Thermal Energy Length Unit
Thermal Resistivity Unit
Power Unit
The electric charge of an ion, equal to the number of electrons the atom has gained or lost in its ionization multiplied by the charge on one electron. This class contains the following instance(s): "atomic number".
Atomic Charge Unit
Capacitance is a measure of the amount of electric charge stored (or separated) for a given electric potential.
This class contains the following instance(s): "Abfarad", "Farad", "MicroFarad", "NanoFarad", "PicoFarad", "Statfarad".
Capacitance Unit
Magnetic flux is a measure of quantity of magnetism, taking into account the strength and the extent of a magnetic field. The SI unit of magnetic flux is the weber (in derived units: volt-seconds), and the unit of magnetic field is the weber per square meter, or tesla. [Wikipedia]
This class contains the following instance(s): "Maxwell", "Unit pole", "Weber".
Magnetic Flux Unit
Exposure Unit
The volume charge density is the amount of electric charge in a volume. It is measured in coulombs per cubic metre (C/m^3). Since there are positive as well as negative charges, the charge density can take on negative values. [Wikipedia]
Electric Charge Volume Density Unit
Luminous Intensity Unit
prefix unit
0.00
All units relating to specificaiton of angles.
Angle unit
coherent derived unit
reference thing
Magnetic Flux Density Unit
Angular Velocity Unit
dimension inverse
Linear Velocity units measure change of length per unit time. Examples include meters per second, miles per hour, knots, etc.
Linear Velocity Unit
1
This property relates a system of units with a unit of measure that is either a) defined by the system, or b) accepted for use by the system and is convertible to a unit of equivalent dimension that is defined by the system. Systems of units may distinguish between base and derived units. Base units are the units which measure the base quantities for the corresponding system of quantities. The base units are used to define units for all other quantities as products of powers of the base units. Such units are called derived units for the system.
system unit
rights
Quantity Kind Category
Prefixes are either binary or decimal.
Prefix Unit
When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion.
Different coefficients of thermal expansion can be defined for a substance depending on whether the expansion is measured by:
* linear thermal expansion
* area thermal expansion
* volumetric thermal expansion
These characteristics are closely related. The volumetric thermal expansion coefficient can be defined for both liquids and solids. The linear thermal expansion can only be defined for solids, and is common in engineering applications.
Some substances expand when cooled, such as freezing water, so they have negative thermal expansion coefficients.
For exactly isotropic materials, the area thermal expansion coefficient is very closely approximated as twice the linear coefficient.
Area Thermal Expansion Unit
A type specification for all units that are used in the SI standard.
Used With SI Unit
unit system
conversion offset
Mass Amount Of Substance Unit
Chemistry Unit
Linear Acceleration Unit
exact constant
Electrical resistance is a ratio of the degree to which an object opposes an electric current through it, measured in ohms. Its reciprocal quantity is electrical conductance measured in siemens.
This class contains the following instance(s): "Abohm", "Ohm", "Statohm".
Resistance Unit
This property relates a system of units to a unit of measure that is defined within the system in terms of the base units for the system. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.
derived unit
1
Rate Of Return Unit
Amount Of Substance Unit
Data Rate Unit
This property relates a unit of measure with the unit system that defines the unit.
defined unit of system
description
reference unit
Temperature Unit
UCPG
subject
creator
UAP
Communications Unit
This property associates a system of quantities with an enumeration that enumerates the base dimensions of the system in canonical order.
base dimension enumeration
Logarithmic units are abstract mathematical units that can be used to express any quantities (physical or mathematical) that are defined on a logarithmic scale, that is, as being proportional to the value of a logarithm function. Examples of logarithmic units include common units of information and entropy, such as the bit, and the byte, as well as units of relative signal strength magnitude such as the decibel.
Logarithmic Unit
Electric current is the flow (movement) of electric charge. The SI unit of electric current is the ampere, and electric current is measured using an ammeter. This class contains the following instance(s): "Abampere", "Ampere", "Biot", "Statampere".
Electric Current Unit
1
An SI unit
SI Unit
Area Angle Unit
Electric current density is a measure of the density of flow of a conserved charge. Usually the charge is the electric charge, in which case the associated current density is the electric current per unit area of cross section, but the term current density can also be applied to other conserved quantities. It is defined as a vector whose magnitude is the current per cross-sectional area. [Wikipedia]
In SI units, the electric current density is measured in amperes per square metre. This class contains the following instance(s): "Ampere per square meter".
Electric Current Density Unit
Thermal Diffusivity Unit
1
Thermal Conductivity Unit
UST
integer percentage
Video Frame Rate Unit
Energy And Work Unit
literal
base quantity kind of system
Atomic Physics Unit
Absorbed Dose Unit
UD
The currency exponent indicates the number of decimal places between a major currency unit and its minor currency unit. For example, the US dollar is the major currency unit of the United States, and the US cent is the minor currency unit. Since one cent is 1/100 of a dollar, the US dollar has a currency exponent of 2. However, the Japanese Yen has no minor currency units, so the yen has a currency exponent of 0.
currency exponent
Decimal Prefix Unit
Mass Temperature Unit
A magnetic field is a vector field that permeates space and which can exert a magnetic force on moving electric charges and on magnetic dipoles (such as permanent magnets). [Wikipedia] The strength of a magnetic field at a point in space is the magnitude of the field vector at that point.
This class contains the following instance(s): "Ampere per meter", "Ampere turn per inch", "Ampere turn per meter", "Oersted".
Magnetic Field Strength Unit
1
This property relates a unit system with a unit of measure that is defined by the system.
defined unit
This property relates a quantity kind to its generalization. A quantity kind, PARENT, is a generalization of the quantity kind CHILD only if
1. PARENT and CHILD have the same dimensions in every system of quantities;
2. Every unit that is a measure of quantities of kind CHILD is also a valid measure of quantities of kind PARENT.
generalization
When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion.
Different coefficients of thermal expansion can be defined for a substance depending on whether the expansion is measured by:
* linear thermal expansion
* area thermal expansion
* volumetric thermal expansion
These characteristics are closely related. The volumetric thermal expansion coefficient can be defined for both liquids and solids. The linear thermal expansion can only be defined for solids, and is common in engineering applications.
Some substances expand when cooled, such as freezing water, so they have negative thermal expansion coefficients. [Wikipedia]
Thermal Expansion Unit
1
Serum Or Plasma Level Unit
Molar Concentration Unit
Coefficient Of Heat Transfer Unit
USE
A positive change limit between consecutive sample values for a parameter. The Positive Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.
Positive delta limit
This property relates a unit of measure to the unit system in which the unit is derived from the system's base units with a proportionality constant of one.
derived unit of system
UFC
Units that measure time.
Time Unit
Activity Unit
Signal relative to an underlying signal
Signal Detection Threshold Unit
order
Heart Rate Unit
1
SI Derived Unit
Electric Flux Unit
float percentage
Acceleration Unit
Permittivity Unit
Mechanics Unit
Concentration Unit
Pressure or stress rate
unit for
vector magnitude
1
1
This class contains units of measure for specific heat capacity at a constant pressure.
Specific Heat Pressure Unit
string1024
The relative standard uncertainty of a measurement is the (absolute) standard uncertainty divided by the magnitude of the exact value.
relative standard uncertainty
quantity kind of system
The standard uncertainty of a quantity is the estimated standard deviation of the mean taken from a series of measurements.
standard uncertainty
Bending Moment Or Torque Unit
This property relates a unit of measure with a unit system that does not define the unit, but allows its use within the system. An allowed unit must be convertible to some dimensionally eqiuvalent unit that is defined by the system.
allowed unit of system
system base quantity kind
Force Per Electric Charge Unit
UF
prefix unit of system
UBM
A unit code is a numeric string that uniquely identifies a unit
code
system quantity kind
Absorbed Dose Rate Unit
Linear Momentum Unit
value for quantity
Mass Unit
1
Time Squared Unit
U
system dimension
Plane Angle Unit
A property to relate an observable thing with a quantity value (qud:QuantityValue)
value
Heat Flow Rate Unit
with attribution to
The solid angle subtended by a surface S is defined as the surface area of a unit sphere covered by the surface S's projection onto the sphere. A solid angle is related to the surface of a sphere in the same way an ordinary angle is related to the circumference of a circle. Since the total surface area of the unit sphere is 4*pi, the measure of solid angle will always be between 0 and 4*pi.
Solid Angle Unit
1
UH
Event Unit
Mass Per Volume Unit
1
Dose Equivalent Unit
Radiometry Unit
1
Frequency Unit
Velocity Unit
Momentum Unit
UTD
This property relates a quantity kind to its specialization(s). For example, linear velocity and angular velocity are both specializations of velocity.
specialization
Dynamic Viscosity Unit
Thermal Resistance Unit
1
Microbial Formation Unit
Atomic Mass Unit
An element of an enumeration
element
UCMN
Heat Capacity And Entropy Unit
1
Units which quantify specific energy, i.e. energy per unit mass.
Specific Energy Unit
1
Time Area Unit
Catalytic Activity Unit
1
numeric value
system derived quantity kind
Space And Time Unit
Turbidity is the cloudiness or haziness of a fluid caused by individual particles (suspended solids) that are generally invisible to the naked eye, similar to smoke in air.
Turbidity Unit
1
conversion multiplier
This class contains units that measure financial quantities, such as currency, transactions, rates of return, etc.
Financial Unit
All SI units are derived from the SI Base units
SI Base Unit
Force Unit
Angular Acceleration Unit
Luminance Unit
Thrust To Mass Ratio Unit
UCHM
Thermal Insulance Unit
A negative change limit between consecutive sample values for a parameter. The Negative Delta may be the encoded value or engineering units value depending on whether or not a Calibrator is defined.
negative delta limit
This class is for describing the enumerations themselves. Having an enumerated value is one concept. Having a way to descrive the set of enumerated valies is a distinct need. An enumeration is a collection of enumeration elements. In some cases it is necesaary to refer to the enumeration as opposed to one of its values.
Enumeration
This property relates a unit of measure with a system of units that either a) defines the unit or b) allows the unit to be used within the system.
unit of system
The ratio of power to electric charge is proportional to the rate of change of electric potential.
Energy per Electric Charge Unit
This class is for all enumerated and/or coded values. For example, it contains the dimension objects that are the basis elements in some abstract vector space associated with a quantity kind system. Another use is for the base dimensions for quantity systems. Each quantity kind system that defines a base set has a corresponding ordered enumeration whose elements are the dimension objects for the base quantity kinds. The order of the dimensions in the enumeration determines the canonical order of the basis elements in the corresponding abstract vector space.
Enumerated Value
Length Temperature Unit
The electric dipole moment (or electric dipole for short) is a measure of the polarity of a system of electric charges. [Wikipedia]
This class has the following instance(s): "Coulomb meter", "Debye".
Electric Dipole Moment Unit
Kinematic Viscosity Unit
Biomedical Unit
Volume per mass unit
Information Entropy Unit
Molar Energy Unit
Light Unit
A system of units is a set of units which are chosen as the reference scales for some set of quantity kinds together with the definitions of each unit. Units may be defined by experimental observation or by proportion to another unit not included in the system. If the unit system is explicitly associated with a quantity kind system, then the unit system must define at least one unit for each quantity kind.
System of Units
This property relates a system of units to a base unit defined within the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.
base unit
Science And Engineering Unit
exact match
UROY
This property relates a unit of measure to the system of units in which it is defined as a base unit for the system. The base units of a system are used to define the derived units of the system by expressing the derived units as products of the base units raised to a rational power.
base unit of system
units for measuring human resources
Human Unit
a property to relate an observable thing with a quantity (qud:Quantity)
quantity
Gravitational Attraction Unit
Mass Per Area Unit
Illuminance Unit
Area Unit
Mass Per Time Unit
The class of units used to measure the properties of electricity and magnetism.
Electricity And Magnetism Unit
Permeability Unit
A Resource Unit is a unit for measuring the amount of various types of resources.
Resource Unit
USI
Angular Momentum Unit
Luminous Efficacy Unit
Area Temperature Unit
When the temperature of a substance changes, the energy that is stored in the intermolecular bonds between atoms changes. When the stored energy increases, so does the length of the molecular bonds. As a result, solids typically expand in response to heating and contract on cooling; this dimensional response to temperature change is expressed by its coefficient of thermal expansion.
Different coefficients of thermal expansion can be defined for a substance depending on whether the expansion is measured by:
* linear thermal expansion
* area thermal expansion
* volumetric thermal expansion
These characteristics are closely related. The volumetric thermal expansion coefficient can be defined for both liquids and solids. The linear thermal expansion can only be defined for solids, and is common in engineering applications.
Some substances expand when cooled, such as freezing water, so they have negative thermal expansion coefficients. [Wikipedia]
Linear Thermal Expansion Unit
Luminous Energy Unit
quantity value
A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.
coherent unit of system
Binary Prefix Unit
A Base Unit is a unit adopted by convention for a base quantity.
Base Unit
contributor
Radiant Intensity Unit
Volume per Time Squared Unit
Force Per Length Unit
Linear Energy Transfer Unit
An electric current flowing around a circuit produces a magnetic field and hence a magnetic flux through the circuit. The ratio of the magnetic flux to the current is called the inductance, or more accurately self-inductance of the circuit. [Wikipedia]
This class contains the following instance(s): "Abhenry", "Henry", "Micro Henry", "Milli Henry", "Stathenry".
Inductance Unit
Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. Electrically charged matter is influenced by, and produces, electromagnetic fields. The interaction between a moving charge and an electromagnetic field is the source of the electromagnetic force, which is one of the four fundamental forces.
Electric Charge Unit
Electric Charge Per Amount Of Substance Unit
The default element in an enumeration
default
UMH
0
The strength of the electric field at a given point is defined as the force that would be exerted on a positive test charge of +1 coulomb placed at that point; the direction of the field is given by the direction of that force. Electric fields contain electrical energy with energy density proportional to the square of the field intensity. The electric field is to charge as gravitational acceleration is to mass and force density is to volume.
Electric Field Strength Unit
A "Space And Time" Unit with the following instance(s): "Cubic foot per minute", "Cubic foot per second", "Cubic inch per minute", "Cubic meter per second", "Cubic yard per minute", "Gallon per day", "Gallon per minute".
Volume Per Time Unit
Specific Heat Capacity Unit
A coherent unit of measurement for a unit system is a defined unit that may be expressed as a product of powers of the system's base units with the proportionality factor of one.
coherent unit
This property relates a unit of measure to the system of units in which it is defined as a derived unit. That is, the derived unit is defined as a product of the base units for the system raised to some rational power.
derived unit of system
Electrical conductance is the inverse of electrical resistance. It measures the ease with which electricity flows along a path through an electrical element.
This class contains the following instance(s): "Abmho", "Mho", "Siemens", "Statmho".
Conductance Unit
Mass Per Length Unit
Currency Unit
Electric Charge Area Density Unit
UNECE common code
RF-Power Unit
UPHS
quantity kind
Amount of substance temperature unit
derived quantity kind of system
Thermodynamics units are units that provide reference scales for quantifying the conversion of energy into work, as well as heat and its relation to macroscopic variables such as temperature and pressure.
Thermodynamics Unit
Luminous Flux Unit
Pressure Or Stress Unit