Function propagation through nested systems

Abstract

Concepts of function are central to design but statements about a device's functions can be interpreted in different ways. This raises problems for researchers trying to clarify the foundations of design theory and for those developing design support-tools that can represent and reason about function. By showing how functions relate systems to their sub-systems and super-systems, this article illustrates some limitations of existing function terminology and some problems with existing function statements. To address these issues, a system-relative function terminology is introduced. This is used to demonstrate that systems function not only with respect to their most local super-system, but also with respect to their more global super-systems.

A new model of conceptual design based on Scientific Ontology and intentionality theory. Part II: The process model

“…This is because the solution concepts of the NFPS model must exist in the objective world. For the design of social-technical systems, interested readers can find some valuable approaches and discussions in some recent research (e.g., Kroes et al, 2006;De Weck et al, 2011;Crilly, 2013).…”

A Comparative Case Study of Functional Models to Support System Architecture Design

“…The device-centric functions are the outcome of the deployment of the environment centric functions. Crilly [12] highlights the necessity of these two views to think of system's, in the context of nested systems. Tomiyama [5] identifies four major purposes of functional descriptions: (1) To represent the purpose of the artefact, (2) To explain the behavior, structure, (3) To capture customer requirements and (4) To illustrate the overview of the system.…”

Synthesis of Functional Models From Use Cases Using the System State Flow Diagram: A Nested Systems Approach

“…The interest for methodologies for conceptual and architecture analysis of complex multi-modal systems is well reflected by recent literature (see for example Liu et al 2013, and2015;Mokhtarian et al, 2017). Crilly's (2013Crilly's ( , 2015 model of the nesting structure of systems within super-systems and the role of function modelling to map the propagation of flows through nested systems, provided a reference framework for the research presented in this paper. Our analysis centred on the function modelling aspects, and identified two distinct tasks:…”

“…These approaches are currently limited by their architecture dependence through the use of physical simulation models; the need to evolve towards solution independent functional modelling has been recognised (see for example Huang et al, 2016). The approach behind the work presented in this paper is underpinned by the reference model of a complex system provided by Crilly (2015) which promotes the idea of multiple nested systems and the propagation of roles and functions through the nested systems (Crilly, 2013). Figure 1 provides an illustration of Crilly's nested systems concept and propagation of functions that supports the fulfilment of multiple roles in conjunction with other systems -all nested in a supersystem.…”

“…The System State Flow Diagram (SSFD) (Yildirim et al, 2017) is used as the reference function modelling methodology; this paper provides further insights for the SSFD based function modelling, emphasizing the strength of this framework for supporting topdown function modelling of complex multidisciplinary systems. The consideration of operation modes / use cases structure of systems analysis in this paper introduces new perspectives to the architecture-based concept of nesting of function models discussed by Crilly (2013 and2015). In this paper we consider three types of nesting of functional models in relation to the analysis of a complex system with multiple levels of decomposition, as follows:…”