Tag Archives: sustainability

More material

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In previous posts I have mentioned the need for ‘more material’ in order to reduce the probability of failure.  This is a little sloppy, since there are, at least, two options buried in these statements.  Namely, the simple one, which is to add a greater mass of material; and the alternative, which is to use a stronger but lighter material, i.e. a more sophisticated material, e.g. a composite.  These are usually also more expensive but can also provide opportunities to incorporate sustainability via bio-based recyclability [for information on bio-based composites see http://www.ag.ndsu.edu/bioepic/documents/symposium/NDS%20Bio-BasedMaterials-DRZAL-10-07-final.pdf%5D.

Model validation

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Front cover of ASME V&V 10-2006, Guide for verification and validation in computational solid mechanics, American Society of Mechanical Engineers, New York, 2006.

Why is validation important?  Validation of computational mechanics models is defined as ‘determining the degree to which a model is an accurate representation of the real world from the perspective of the intended uses of the model’, according to  ASME V&V 10-2006.  So, the validation of models of structural integrity for engineering design provides information about the degree to which the simulation results from the model can be believed.  This in turn helps in making decisions about how little material, and in what configuration, should be used to create elegant, sustainable designs that are unlikely to fail. So validation of computational mechanics models is an essential step in solving the ‘two earths’ dilemma (see post on August 13th, 2012).

Population crunch

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The current growth trends suggest that the global population will increase by a billion in the next few decades, with perhaps 500 million additional people in Africa and the same number in Asia [see http://www.un.org/esa/population/publications/longrange2/WorldPop2300final.pdf%5D.  Another observable trend is urbanisation.  Thus, taking these together it is not unreasonable to expect most of the population growth to occur in cities.  The typical size of cities in Africa is 0.5 million people and so we might expect to see 1000 new cities in Africa and perhaps around 500 in Asia where the average size is 1 million.

The challenge for engineers is to provide an acceptable quality of life in these cities.  This involves providing a built environment, food, energy, transport and health care using scientific advances in novel materials, information communication technology, biosciences, electronics and photonics.

Can it be done? Probably, but it will require a higher level of innovation than is the norm at the moment, otherwise the population crunch might take many forms.

Waste is unavoidable

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Image from http://www.nucleartourist.com/systems/ct.htm
Courtesy KKN Liebstadt NPP

If you read my previous post on perfect engines, then you might have thought a heat engine that did not discharge any heat would be more efficient.  However, this would contravene the second law of thermodynamics, which requires that every real process must generate an increase in disorder, in this case by the discharge of waste heat.  Thermodynamicists like to call this increase in disorder, an increase in ‘entropy’.

A consequence of the second law of thermodynamics is that the entropy, or disorder, of the universe is always increasing; but now I have strayed from engineering to physics.  Together with Bob Handscombe, I wrote a book on this topic called the ‘Entropy Vector: Connecting science and business’.  It was not a best-seller but it got some good reviews, see http://www.worldscientific.com/worldscibooks/10.1142/5365#t=reviews.