Description:
Thermophysical and thermochemical property data represent
a key foundation for development and improvement of all chemical
process technologies. These data are also critical for support of
fundamental research in Physics, Chemistry, Biology, and Material
Science. An unprecedented growth of the number of custom-designed
software tools for various engineering applications has created
an interoperability problem between the formats and the structure
of the thermodynamic data files and required input/output structure
designed for various application software products. This problem
is reflected in the extremely time- and resource-consuming efforts
to collect the data within a particular data management environment
using numerous data sources of different nature. The development
of standards for thermodynamic data storage and exchange is the
only principal solution of this problem.
Within the last 20 years this problem has become a major obstacle
for development of efficient process design software tools requiring
generation of extensive thermophysical and thermochemical property
data packages. The major objective of this project is to establish
an international standard for thermophysical/thermochemical data
storage and exchange to provide a practical solution of this problem.
The development of a standardized XML-based dictionary is the most
powerful instrument to provide an interoperability solution for
interpretation and use thermodynamic data. This dictionary has to
be able to describe the complete set of thermophysical and thermochemical
properties (more than 120), their uncertainties and related metadata.
XML (Extensible Markup Language) avoids common pitfalls in language
design: it is extensible and platform-independent. Since XML files
are essentially textual files, they can be easily analyzed without
the use of specific customized software products and can be read
by a variety of text editors.
The developed XML-based structure will represent a balanced combination
of hierarchical and relational elements. It will explicitly incorporate
structural elements related to basic principles of phenomenological
thermodynamics: thermochemical and thermophysical (equilibrium and
transport) properties, state variables, system constraints, phases,
and units. Meta- and numerical data records will be grouped into
'nested blocks' of information corresponding to data sets. The metadata
records will precede numerical data information, providing a robust
foundation for generating 'header' records for any relational database
where XML-formatted files could be incorporated. The structural
features of the metadata records will ensure unambiguous interpretation
of numerical data as well as data-quality control based on the Gibbs
Phase Rule. Implementation of the Gibbs Phase Rule would provide
users with an indication of inconsistencies in thermodynamic data
before the data are deposited into a data-storage facility. Moreover,
some detailed information included in the metadata records could
serve as a background for independent assessment of uncertainties,
which could be propagated into uncertainties of physical parameters
for reaction streams, and consequently, provide an opportunity for
quantitative characterization of the quality of a chemical process
design.
Commonly accepted IUPAC-based terminology will be used as the foundation
for metadata and numerical data tagging. In addition, the self-explanatory
approach and very limited use of abbreviations will minimize the
time necessary for users to understand the schema and to convert
the XML- formatted data with customized software or commercial XML
parsers.
The dictionary will be designed to take advantage of the modular
nature of XML schemas. In particular, the emphasis will be made
to ensure compatibility with the schema currently being developed
under the scope of the IUPAC project
2002-022-1-024 "Standard XML data dictionaries for chemistry".
By design, there will be only one unit selected for each property
covered by the dictionary. These units will be SI-based, however,
for a number of properties the selected units might be multiples
of SI units to ease interpretation of numerical values. Unit tagging
will be explicitly propagated to every numerical data point as a
part of each property name, thus minimizing the possibility of unit
misinterpretation.
Various methods of numerical data representation commonly used
in publication of experimental property data (e.g., direct, difference
from values at a reference state, ratio of the value to that at
a reference state, etc.) are planned to be incorporated into the
schema.
The developed dictionary will provide elements for storage and
exchange of experimental, critically evaluated, and predicted data.
The schema will have provisions for the expressions of various measures
of the thermodynamic data uncertainties such as standard uncertainty,
combined standard uncertainty, combined expanded uncertainty, and
different types of the precision (repeatability, deviation from
the fitted curve, device specifications). Definitions and descriptions
of all quantities related to the expression of uncertainty in the
dictionary will conform to the Guide to the Expression of Uncertainty
in Measurement, ISO (International Organization for Standardization),
October, 1993.
The developed schema will be validated extensively with data records
managed by the SOURCE Data System, the largest experimental thermodynamic
data storage facility in the world. In addition, validation will
include data files corresponding to publications of experimental
and critically evaluated data in major journals in the field such
as the Journal of Chemical and Engineering Data and the Journal
of Chemical Thermodynamics. The necessary arrangements with the
Editors and Publishers of the journals have been made. To expedite
and automate the process of schema validation, software tools guiding
the process of data capture and generation of XML-formatted files
will be developed on the basis of the formulated dictionary.
Establishment of the XML-based standard for storage and exchange
of the thermodynamic data will provide an easy-to-use and extremely
efficient pipeline to transport data from data producers to data
users, serving as a hub tool and assuring interoperability between
various data management systems and operation platforms.
The project will be conducted in close cooperation with industry
(Design Institute for Physical Properties, DIPPR, combining thermophysical
data activities for more than 40 major companies worldwide).
Progress:
"ThermoML" is reserved namespace for the XML-based IUPAC
standard for experimental and critically-evaluated thermodynamic
property data storage and capture
> www.iupac.org/namespaces/ThermoML/
On 29 January 2004, the project task group
met at the ESDU International plc, London, U.K > See report published
in Chem.
Int.
July-Aug 2004
A manuscript is being prepared for publication
in Pure Appl. Chem. A final document was submitted to public
review comments until 31 January 2006.
A
one-day symposium on ThermoML: Purpose, Structure, and
Applications will be held on Monday, 27 March 2006
in Atlanta, GA ... more
|
Project completed - IUPAC Recommendations published in Pure
Appl. Chem.
78(3), 541-612, 2006
+ Supporting Information (zip file
- 38KB)
> update 18 Dec 2006: In case
of minor
differences between the text describing ThermoML (Pure Appl.
Chem., 2006, 78, 541-612) and the ThermoML schema (ThermoML.xsd),
the schema should always be considered normative.
Last update: 19 December 2006
<project announcement published
in Chem.
Int.
Jan 2004>