Engineering Complex Systems & Complex Systems Engineering: Lessons and Tools for Sustainability

Scientific breakthroughs occur at the edges of disciplines. Often ideas originating in one field find successful applications in others, sometimes leading to revolutionary shifts. Complexity is regarded by many to be such an example. The word ?complex,? signifying ?composed of parts,? comes from a French word, ca. 1650; its meaning as an adjective, ?not easily analyzed,? is first recorded in 1715. Both meanings come close to how we define complex systems today. Complex systems can be identified by what they do ? display organization without a central organizing principle (emergence), and also by how they may or may not be analyzed ? decomposing the system and analyzing subparts does not necessarily give a clue as to the behavior of the whole.

Various aspects of these ideas appear in sociology; physical, biological and chemical sciences; computer science; mathematics; and many branches of engineering. The extended toolkit for complexity includes statistical mechanics, nonlinear dynamics, network theory, and agent based modelling. New tools lead to new applications, often blurring traditional boundaries across domains and disciplines.

Yet the transitions among domains are far from trivial. Consider engineering. The hallmarks of complex systems are adaptation, self-organization, and emergence. No single designer designed the web or the metabolic processes within a cell. Engineering is not about letting things be; engineers engineer. Engineering is about making things happen, about consistency of design, about convergence. Engineering has typically dealt with complicated systems as opposed to complex ones. In complicated systems parts have to work in unison to accomplish a function. One key defect (in one of the many critical parts) brings the entire system to a halt. This is why redundancy is built into designs when system failure is not an option.

Yet engineering can undoubtedly benefit from the adoption of complex systems tools to its standard toolkit. The resulting changes can be profound. Ecological systems, supply chains, and materials self-assembly can be seen in a new light. Complex systems tools represent an opportunity for a significant leap across areas, potential paradigm shifts in established research areas, and even the creation of new disciplines.

Examples of application problems cover the range of engineered systems, such as concerns about the robustness of power grids, telecommunication networks, to organizational systems, supply chains, and transportation networks. But they also include the understanding of various types of environmental and ecological systems. The field of sustainability requires a confluence of a wide range of disciplines and a system of systems viewpoint. And one of the enabling capabilities should be the application of complex problems tools.

References

J.M. Ottino, Complex systems, AIChE Journal, 49, 292-299 (2003).

J.M. Ottino, Engineering complex systems, Nature, 427, 399 (2004).

L.A.N. Amaral and J.M. Ottino, Complex networks: Completing the framework for the study of complex systems, European Physics Journal, 38, 47-162, (2004).