Foundations of Systems Engineering
Part 2 is a guide to knowledge associated with systems , particularly knowledge relevant to systems engineering (SE). Part 2 elaborates on the underlying systems ideas upon which the following parts of the SEBoK are based, thus providing a foundation for the remainder of the SEBoK. Part 2 also defines the key principles of a Systems Approach, which will be referred to directly in explaining the practices of SE.
To download a PDF of Part 2, please click here.
Knowledge Areas in Part 2: Systems
Part 2: Systems, contains the following knowledge areas:
- Systems Thinking
- System Science
- Representing Systems with Models
- Systems Approach
- Systems Challenges
Scope of Part 2
Part 2 of the SEBoK contains a guide to knowledge about systems, which is relevant to a full understanding of SE. As such, it deals with both abstract concepts about systems and practical principles which guide the use of these concepts to underpin the understanding, creation, management, and use of (socio-technical) engineered systems .
- Concepts are sub divisions of knowledge that describe a single idea or property of things.
- Principles are statements which guide the way we might think or act in a given situation as a consequence of one or more concepts.
For example, the concept of openness states that some systems must exchange energy, information or material with their environment to exist and function. Principles based on this concept include that an open system can only be fully understood in its environment , or that changes to the environment may change how a system behaves.
The following diagram summarizes the way in which the knowledge in SEBoK Part 2 is organized.
The aim of this model is to provide a guide to the major aspects of systems knowledge in such a way that it can be useful to SE in 2 ways:
- To define an underlying theory for SE standards and descriptions; and
- To describe a fundamental way of thinking about complex situations as systems, which should guide the way in which people apply SE practices to best effect.
Each part of this diagram is explained in more detail below. The model is divided into four sections, each describing how we have treated systems knowledge in the SEBoK.
- The System Science Knowledge Area provides an overview of the most influential movements in systems science. This section explores the chronological development of systems knowledge and discusses some of the different approaches taken in applying it to real problems. This is useful background knowledge of general interest to systems engineers, in particular those involved in development of SE standards and descriptions.
- The Systems Thinking Knowledge Area describes key concepts shared across systems research and practice and organizes them as a system of related ideas. Understanding this way of thinking should be a key competence for anyone undertaking systems research or practicing SE.
- The Representing Systems with Models Knowledge Area considers the key role that abstract models play in both the development of system theories and the application of system thinking.
- The Systems Approach Knowledge Area defines a structured problem or opportunity discovery, as well as exploration and resolution approaches that can be applied to all engineered systems , which is based on systems thinking. This KA provides principles that map directly to SE practice.
It should be noted that, while the knowledge presented in this part of the SEBoK has been organized into these four areas to facilitate understanding, the intention is to present a rounded picture of research and practice based on system knowledge. These four knowledge areas are tightly coupled and should be seen together as a system of ideas for connecting understanding, research, and practice, based on system knowledge which applies to all types of domains and underpins a wide range of scientific, management, and engineering disciplines.
Systems Thinking
The origins of systems thinking began in attempts to better understand complex situations in biology, organizations, control, etc. From these attempts come a set of fundamental concepts defining the idea of an open system and associated principles such as holism, emergence, etc. which have become the foundations of system thinking.
Over time, systems thinking has been extended and refined by the creation of a set of abstract system models and a system of systems-concepts, which apply to all systems, independent of their domain.
System science is a community of research and practice which is based on systems thinking, and which adds to and evolves the systems thinking body of knowledge.
Systems Thinking stands alone as a way of thinking which “Systems People” can use to gain a fuller understanding of any situation and through this, guide a wide range of human activity.
Checkland (1999) discusses the use of systems thinking as a way to both understand and intervene in a problem situation. Lawson (2010) defines three related contexts in which systems thinking can be used:
- to better understand a current real world situation by defining an abstract Situation System;
- to describe the Respondent System that might be used to understand, use, manage, sustain or change the situation system;
- to understand how one or more system assets needs be acquired, modified, or created to achieve the purpose of the respondent system.
Systems Science
systems science is an interdisciplinary field of science that studies the nature of complex systems in nature, society, and science. It aims to develop interdisciplinary foundations, which are applicable in a variety of areas, such as engineering, biology, medicine and social sciences. This systems science is practiced by a community of system researchers who perform research based on systems thinking.
Many systems science practitioners also develop system methodologies that provide a framework of concepts and principles for tackling specific aspects of system problems.
These methodologies are grouped around a set of paradigms which define particular world views or ways of thinking about systems, e.g., hard systems, soft systems, system dynamics, etc.
Another output of system science is the emergence of a theory of problem solving (also referred to as a theory of engineering, design, intervention, etc.). Some of this theory is published, and some is embedded in the methodologies.
The work of system science expands the shared understanding of systems and is used to evolve the body of knowledge of systems thinking, both in expanding the system-concepts, and in creating new models or modeling notations.
Systems science should be conducted by researchers who are themselves competent in systems thinking. As discussed above, this will include understanding the situation system under study, creating a research resolution system, and understanding any needed research system assets.
Systems Approach
SE lifecycle and process definitions, standards, and guides are underpinned by aspects of systems science and make use of system methodologies, but this is often not done in a rigorous or consistent way. Those conducting SE are often simply following process definitions and are not aware of the fundamentals and relevance of systems thinking.
A Systems Approach can be defined, synthesizing elements of Systems Science to create:
- A framework of activities that can be applied to complex situations requiring engineered system based solutions.
- System principles within each activity that relate back to the systems thinking models and concepts.
The activities and principles of the systems approach can be mapped onto the processes of SE to increase the system science foundations of SE.
This mapping will provide guidance on which system-concepts should be considered when applying a process and which system models can be used to support process activities.
SE should be practiced by those who are themselves competent in systems thinking. As discussed above, this will include understanding the problem or opportunity situation of a system, creation of a respondent system, and the understanding of life cycle management any system products or services assets.
References
Works Cited
Checkland, P B. 1999. Systems Thinking, Systems Practice. Chichester, England, UK: John Wiley and Sons.
Lawson, H. 2010. A Journey Through the Systems Landscape. London, UK: College Publications, Kings College, UK.
Primary References
Checkland, P. B. 1999. Systems Thinking, Systems Practice. Chichester, UK: John Wiley & Sons Ltd.
Lawson, H. 2010. A Journey Through the Systems Landscape. London, UK: College Publications, Kings College, UK.
Additional References
MITRE Corporation. 2011. Systems Engineering Guide: Comprehensive Viewpoint. Accessed 2/28/2012 at http://www.mitre.org/work/systems_engineering/guide/enterprise_engineering/comprehensive_viewpoint/
MITRE Corporation. 2011. Systems Engineering Guide: Systems Thinking. Accessed 2/28/2012 at http://www.mitre.org/work/systems_engineering/guide/enterprise_engineering/comprehensive_viewpoint/systems_thinking.html
Senge, P. M. 1990. The Fifth Discipline: The Art & Practice of the Learning Organization. New York, NY: Doubleday Business.
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