QUDT.org is a 501(c)(3) public charity nonprofit organization founded to provide semantic specifications for units of measure, quantity kind, dimensions and data types.
QUDT is an advocate for the development and implementation of standards to quantify data expressed in RDF and JSON.
Our mission is to improve interoperability of data and the specification of information structures through industry standards for Units of Measure, Quantity Kinds, Dimensions and Data Types.
QUDT.org operates thanks to volunteers, but we do have infrastructural costs of course. If you value the QUDT ontologies as a resource available to all, please consider a
DONATION
of any amount (tax deductible in the USA). That will allow us to keep going and growing.
Why QUDT.org
QUDT.org exists to make the QUDT Ontologies, derived models and vocabularies available to the public.
Originally, QUDT models were developed for the NASA Exploration Initiatives Ontology Models (NExIOM) project, a Constellation Program initiative at the AMES Research Center (ARC).
Use Cases Benefitting From QUDT
QUDT is more than a set of vocabularies representing the various quantity and unit standards. It can be used to solve problems. Some of the associated use cases are itemized below:
Conversion between single and complex unit types
Dimensional analysis of equations
Finding out equivalent units in different systems of units
Finding out equivalent quantity kinds in different systems of quantities
Current Activities
Please see our
Announcements Page
on GitHub
QUDT BaseURIs
The DOI reference for citations of QUDT is:
QUDT is comprised of several linked ontologies. The core design pattern of the QUDT ontology is shown here:
The table below provides the Base URIs for these ontologies.
Ontology
Base URI
Main QUDT Ontology
QUDT Datatype Ontology
QUDT Units Vocabulary
QUDT QuantityKinds Vocabulary
QUDT DimensionVectors Vocabulary
QUDT Physical Constants Vocabulary
QUDT Systems of Units Vocabulary
QUDT Systems of Quantity Kinds Vocabulary
Governance
QUDT is governed by a board of directors from different organizations.
This work is licensed under a
Creative
Commons Attribution 4.0 International License
QUDT Resources
QUDT Catalog Latest Release
QUDT Incoming Reference Explorer
QUDT Catalog Release 2.1
GitHub Public Repository
Introduction to QUDT slide presentation
Introductory User Guide
QUDT Wiki
Unit Vocabulary Submission Guide
QUDT Wiki
QUDT EDG environment
QUDT SPARQL Endpoint
Community Resources
QUDTLib: Java Unit Conversion Library based on QUDT
jQUDT (Another Java QUDT Unit Conversion Library)
occam-qudt (A Java library for math operations using QUDT)
QUDTLib: Javascript Unit Conversion Library based on QUDT
Loop3d Profile and Vocabulary of Units
Searcheable QUDT Units browser
Key References
The NIST Guide for the use of the International System of Units
International Vocabulary of Metrology – Basic and General Concepts and Associated Terms
SI Brochure, 9th Edition
Dimensional Analysis, Percy Williams Bridgman, Yale University Press (1922)
QUDT In The News
The ABCs of QUDT - Blackwood
The QUDT System for Dimensional Analysis and Unit Conversions - Winston
Semantic Web for the Working Ontologist - Allemang, Hendler, Gandon