Investigating Relationships and Semantic Sets amongst System Lifecycle Properties (Ilities)

Abstract

The ilities are properties of engineering systems that often manifest and determine value after a system is put into initial use (e.g. resilience, interoperability, flexibility). Rather than being primary functional requirements, these properties concern wider system impacts with respect to time and stakeholders. Over the past decade there has been increasing attention to ilities in industry, government and academia. Our research suggests that investigating ilities in sets may be more meaningful than study of single ilities in isolation. Some ilities are closely related and do in fact form semantic sets. Here, we use two methods to investigate over twenty ilities in terms of their prevalence and their interrelationships. We look for trends related to ilities of interest in relation to system type and an understanding of their collective use. First, we conducted a prevalence analysis of 22 ilities using both the internet as well as the Compendex/Inspec database as a source. We found over 1,275,000 scientific articles published between 1884 and 2010 and over 1.9 billion hits on the internet, exposing a clear prevalence-based ranking of ilities. Two questions we seek to address are: why and how are the ilities related to one another, and what can we do with this information. Initial steps to answer the first question include a 2-tupel-correlation matrix analysis that exposes the strongest relationships amongst ilities based on concurrent usage. Moreover, we conducted some preliminary experiments that indicate that a hierarchy of ilities with a few major groupings may be most useful. The overall objective for this research is to develop a formalframework and prescriptive guidance for effectively incorporating sets of ilities intothe design of complex engineering systems.