Scientific Units in the Electronic Age Stuart J. Chalk, Department of Chemistry University of North Florida CINF Paper 49 – 251 st ACS Meeting Spring 2016 #ACSCINFDataSummit

 Why Do Computers Need to Know About Units?  What Do We Need?  Unit Systems  Implementation of Units for Computers  Text Units  XML Units  Semantic Units  What We Really Need  Things To Do  Conclusion Outline From:

 Computers are used to represent data  Data is not useful unless it has a context – meaning  Part of the context of data is its unit of measure  Publication of scientific data – it needs definitive units! Why do Computers Need to Know About Units? From:

What Do We Need?  A way to uniquely identify and give meaning to units…  …and dimensions, quantities, properties(?)  A way to uniquely identify and give meaning to fundamental constants and conversion factors  Must describe the semantics of prefixes  Must accommodate all languages (spoken and computer)  Must be usable at different levels of technology  Must be unit system agnostic  Must be as future-proof as possible (extensible/adaptable)

What Do We Need?  A standards organization to host a platform providing unambiguous representations of any unit of measure  Tools/services to allow identification of units that can be used to represent the same quantity  Tools/services to allow systems to interconvert units and provide a mechanism to document the conversion  Must be compliant with the tools/services supporting big data and the semantic web

From:

 International System of Units (SI)  Including CGS and MKS  UK Imperial System  US Customary Units  Burmese  Indian  Astronomical Units  Troy (mass) Units  Historical/Obsolete Units and Unit Systems Unit Systems

Implementations of Units for Computers  Text String  XML (Tagged Text)  Semantically (URI)

 International Virtual Observatory Alliance (IVOA)  Standardization of string representations of unit labels (“VOUnits”) in the astronomy community Text String Representation From:

 MathML (  Presentation of Units  Unit Symbols in Content MathML  Conversion of Units XML Representation cm s cm s kyn cm s cm s kyn

 Geographic Markup Language (GML)  Provides  Unit References (“unitOfMeasure” element)  Unit Definitions (“unitDefinition” element)  “BaseUnit”, “DerivedUnit”, and “ConventionalUnit” XML Representation cubic metre Volume cubic metre Volume

 Scientific, Technical, and Medical Publishing (STTML) Part of the Chemical Markup Language (CML) XML Representation The SI unit of time The SI unit of force kg. An imperial measure of length The SI unit of time The SI unit of force kg. An imperial measure of length

 UnitsML  NIST Project – intended to be published as a standard under OASIS  Fundamental representation of dimensions, units, quantities  UnitsDB a symbiotic project (internal to NIST)  Never formally standardized under OASIS… …and NIST ran out of funding XML Representation

From:

XML Representation From:

XML Representation <units xmlns=" xmlns:q=" xmlns:usym=" SI meter metre mètre m … <units xmlns=" xmlns:q=" xmlns:usym=" SI meter metre mètre m …

XML Representation length l L mega L Θ length l L mega L Θ

 “Semantics” - the branch of linguistics and logic concerned with meaning  Rather than just identify a unit, indicate the meaning of a unit  Resource Description Framework (RDF)  Subject-Predicate-Object “triples”  RDF-XML (  JSON-LD (JSON for Linked Data)  Ontological Definitions Semantic Representation

 Units of Measure Ontology (UO) Semantic Representation

 Semantic Web for Earth and Environmental Technology (SWEET)  “SWEET 2.3 is highly modular with 6000 concepts in 200 separate ontologies.” Semantic Representation

 Quantities, Units, Dimensions and Data Types Ontology (QUDT)  Version  Version  Space Time Vocabulary  Physical Chemistry and Molecular Physics Vocabulary molecular-physics.html molecular-physics.html Semantic Representation

Semantic Units Model From:

Semantic Units Model From:

Semantic Units Model From:

 A Metrology Ontology! What Do We Really Need? From:

Official Metrology Definitions From:

 Write up a summary of current state of units  Develop a proposal to implement units in computers based on best features of existing work  Development of a metrology ontology (33 results on google – none are a general ontology for metrology)  Evaluate support technology needed to implement the ontology  Identify specific use cases and implement solutions  Formalize as a standard, with use cases and example implementations  Applicable for text, XML, and Semantic formats… ...databases, ELNs, instrument software, Things To Do

  Phone:  Skype: stuartchalk  LinkedIn/Slidehare:  ORCID:  ResearcherID: Questions?