Tag Archives: Engineering

Aorta: structure to rupture

Decorative image from a video showing predicted flow through aortic valve and resultant stress in leaflets of valveRegular readers have probably already realised that I have very broad interests in engineering from aircraft and power stations [see ‘Conversations about engineering over dinner and haircut‘ on February 16th, 2022] to nanoparticles interacting with cells [see ‘Fancy a pint of science‘ on April 27th, 2022].  So, it will come as no surprise to hear that I gave a welcome address to a workshop on ‘Aorta: Structure to Rupture‘ last week.  The workshop was organised in Liverpool by one of my colleagues, with sponsorship from the British Heart Foundation, and I was invited to welcome delegates in my capacity as Dean of the School of Engineering.  It was exciting on two levels: speaking, for the first time in more than two years, to an audience who had travelled from around the world to discuss research. And because the topic was closely associated with cardiac dynamics, which is a field that I worked in for nearly twenty years until around 2006.  I was part of an interdisciplinary team modelling the fluid-structure interaction in the aortic valve as it opens when blood is pumped through it by the heart and then closes to prevent back flow into the heart.  The team dispersed after I moved to the USA in 2004.  So speaking to the workshop last week was something of a trip down memory lane for me and led me to look up our last publication in the field.  I was surprised to find it was cited seven times last year.

The image in the thumbnail is a snapshot from a video showing the predicted time-varying distribution of blood flow through the aortic valve and the resultant distribution of stress in the leaflets of the valve during a heart beat.  The simultation is described in our last publication in cardiac dynamics: Carmody, C. J., Burriesci, G., Howard, I. C., & Patterson, E. A.,  An approach to the simulation of fluid–structure interaction in the aortic valve. J. Biomechanics, 39(1), 158-169, 2006.

Exploiting complexity to help society adapt

photograph of a flower for decorative purposes onlyI am worried that engineering has become a mechanism for financial returns in an economic system that values profit above everything with the result that many engineers are unwittingly, or perhaps in a few cases wittingly, supporting the concentration of wealth into the hands of a few capitalists.  At the start of the industrial revolution, when engineering innovation started to make a difference to the way we live and work, very few engineers foresaw the impact on the planet of the large scale provision to society of products and services.  Nowadays most engineers understand the consequences for the environment of their work; however, many feel powerless to make substantial changes often because they are constrained by the profit-orientated goals of their employer or feel that they play a tiny role in a complex system.  Complex systems are often characterised by self-organisation in which order appears without any centralised control or planning and by adaptation to change and experience.  Such systems are familiar to many engineers and perhaps they do not, but should, think of the engineering profession as complex system capable of adaptation and self-organisation in which the actions and decisions of individual engineers will cause the emergence of a new order. Our individual impact might be tiny but by acting we influence others to act and the cumulative effect will emerge in ways that no one can predict – that’s emergence for you.

Diving into three-dimensional fluids

My research group has been working for some years on methods that allow straightforward comparison of large datasets [see ‘Recognizing strain’ on October 28th 2015].  Our original motivation was to compare maps of predicted strain over the surface of engineering structures with maps of measurements.  We have used these comparison methods to validate predictions produced by computational models [see ‘Million to one’ on November 21st 2018] and to identify and track changes in the condition of engineering structures [see ‘Out of the valley of death into a hype cycle’ on February 24th 2021].  Recently, we have extended this second application to tracking changes in the environment including the occurance of El Niño events [see ‘From strain measurements to assessing El Niño events’ on March 17th, 2021].  Now, we are hoping to extend this research into fluid mechanics by using our techniques to compare flow patterns.  We have had some success in exploring the use of methods to optimise the design of the mesh of elements used in computational fluid dynamics to model some simple flow regimes.  We are looking for a PhD student to work on extending our model validation techniques into fluid mechanics using volumes of data from measurement and predictions rather than fields, i.e., moving from two-dimensional to three-dimensional datasets.  If you are interested or know someone who might be interested then please get in touch.

There is more information on the PhD project here.

Intelligent openness

Photo credit: Tom

As an engineer and an academic, my opinion as an expert is sought often informally but less frequently formally, perhaps because I am reluctant to offer the certainty and precision that is so often expected of experts and instead I tend to highlight the options and uncertainties [see ‘Forecasts and chimpanzees throwing darts’ on September 2nd 2020].  These options and uncertainties will likely change as more information and knowledge becomes available.  An expert, who changes their mind and cannot offer certainty and precision, tends not to be welcomed by society, and in particular the media, who want simple statements and explanations.  One problem with offering certainty and precision as an expert is that it might appear you are part of a technocratic subset seeking to impose their values on the rest of society, as Mary O’Brien has argued.  The philosopher Douglas Walton has suggested that it is improper for experts to proffer their opinion when there is a naked assertion that the expert’s identity warrants acceptance of their opinion or argument.  Both O’Brien and Walton have argued that expert authority is legitimate only when it can be challenged, which is akin to Popper’s approach to the falsification of scientific theories – if it is not refutable then it is not science.  An expert’s authority should be acceptable only when it can be challenged and Onora O’Neill has argued that trustworthiness requires intelligent openness.  Intelligent openness means that the information being used by the expert is accessible and useable; the expert’s decision or argument is understandable (clearly explained in plain language) and assessable by someone with the time, expertise and access to the detail so that they can attempt to refute the expert’s statements.  In other words, experts need to be  transparent and science needs to be an open enterprise.

Sources:

Burgman MA, Trusting judgements: how to get the best out of experts, Cambridge: Cambridge University Press, 2016.

Harford T, How to make the world add up: 10 rules for thinking differently about numbers, London: Bridge Street Press, 2020.

O’Brien M, Making better environmental decisions: an alternative to risk assessment, Cambridge MA: MIT Press, 2000.

Walton D, Appeal to expert opinion: arguments from authority, University Park PA: Pennsylvania State University Press, 1997.

Royal Society, Science as an open enterprise, 2012: https://royalsociety.org/topics-policy/projects/science-public-enterprise/report/