Saturday, November 24, 2012

Engineering Antifragile Systems

Antifragility in the context of engineered systems subject to extreme weather and climate change risks could be an important opportunity for engineers.  The word "antifragile" comes from Antifragile: Things that Gain from Disorder by Nassim Nicholas Taleb (Taleb is of "Black Swan" fame).  As we have seen recently along the New York and New Jersey coastline, a key engineering question is "What is the opposite of fragile?"  Most engineers would answer either "resilience" or "robustness."  Taleb feels "antifragile" is better - - if fragility means something that breaks (and numerous systems broke during Hurricane Sandy) under stress, its exact opposite means something that grows stronger under pressure.  Engineering doesn't have a word that captures this condition.

Taleb argues that in a world of increasing uncertainty, antifragility is a secret to our success.  It has always been a secret to our own collective well being.  Evolution is a process in which random events are turned into lasting advantage.  We respond well to pressure - - IQs increase with learning and testing; leg muscles get stronger with running and weight lifting.  Airplanes get safer after each crash and investigation.

In many engineering endeavors, long periods of stability allows risks to accumulate until their is a major disaster.  Volatility can mean that things and systems do not get too far out of kilter.  Disaster-resistant construction and retrofitting  existing building stock should have elements of antifragility thinking.  A significant  opportunity to reduce loss in future events and thus increase resilience is to strengthen and/or retofit the nation's existing building stock.  In the case of hurricanes, the new construction and retrofitting is relatively inexpensive and can include installation of exterior hurricane shutters or replacing windows with impact resistant glass, garage door bracing, strengthening soffits, and securing loose roof shingles.

Jo da Silva in Shifting Agendas: Response to Resilience has outlined characteristics of a resilient system.  It is important for engineering to incorporate antifragility thinking into these characteristics:
  1. Flexibility - the ability to change, evolve and adapt alternative strategies in either the short or longer term.  The favors "soft" rather than "hard" solutions.  Sounds very antifragile.
  2. Redundancy - superfluous/spare capacity to accommodate increasing or extreme/surge pressures/demands.  Redundancy includes diversity, multiple pathways and a variety of options.  I can see elements of antifragility - - diversity and multiple pathways.
  3. Safe Failure - this is related to the ability to absorb shocks and the cumulative effects of slow-onset challenges in ways that avoid catastrophic failure if thresholds are exceeded.  When a part of the system fails it does so progressively rather than suddenly, with minimal impact to other systems.  Failure itself is accepted.  Goes to the heart of antifragility and volatility.
  4. Resourcefulness - the capacity to visualize and act, to identify problems, establish priorities, mobilize resources when conditions exist that threaten to disrupt an element of the system.
  5. Responsiveness - the ability to re-organized, to re-establish function and sense of order following failure.  Re-organizing could be antifragile.
  6. Capacity to Learn - direct experience and failure plays a key role in triggering learning processes.  The systems should have the ability to learn from past experiences and failures, to avoid past mistakes and exercise in future decisions.  The is the heart of antifragile thinking.
  7. Dependency on Local Ecosystems - valuing the services provided by local and surrounding ecosystems (green and blue infrastructure), and taking steps to increase their health and stability.  These services (often undervalued) perform processes such as flood control, temperature regulation pollutant filtration, and local food production.

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