Vol. 26 No. 1
January-February 2004

XML-Based IUPAC Standard for Experimental and Critically Evaluated Thermodynamic Property Data Storage and Capture

IUPAC has approved a project to develop an XML-based IUPAC standard for thermodynamic data communications as one of the activities of the Committee on Printed and Electronic Publication. 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.

The unprecedented growth in the number of custom-designed software tools for various engineering applications has created an interoperability problem between the formats and the structures of the thermodynamic data files and required input/output structures of different software products. This problem is reflected in the extremely time- and resource-consuming efforts required to collect the data within a particular data management environment using numerous data sources of different types. Within the last 20 years this problem has become a major obstacle to developing efficient process-design software tools, requiring generation of extensive thermophysical and thermochemical property data packages. The major objective of this project is to provide a practical solution to the problem by establishing an international standard for thermophysical/thermochemical data storage and exchange.

A standardized XML-based dictionary will provide the most powerful, interoperability solution for interpretation and use of thermodynamic data. Such a 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 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. 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. 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 precision (e.g., repeatability, deviation from the fitted curve, or device specifications).

Establishment of the XML-based IUPAC standard will provide an easy-to-use and extremely efficient pipeline for transferring data from data producers to data users. The standard will serve as a hub tool and assure interoperability between various data management systems and operation platforms.

For more information, contact the Task Group Chairman Michael Frenkel <[email protected]>.

www.iupac.org/projects/2002/2002-055-3-024.html