Tag Archives: Engineering

Out and about

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butterfly-with-branched-scrolls-vaseI have been away from Liverpool a lot in the last few weeks. Teaching in Manchester and London but also visiting Taiwan. In the capital, Taipei they have yellow cabs and a succession of black limos pick up visitors from the airport. I even saw a baseball pro shop but despite the strong American influence, the culture is definitely Chinese so ordering meals and buying train tickets is a challenge if you don’t speak or read Mandarin. I am a Visiting Professor at the National Tsing Hua University and was there to meet with some PhD students and participate in a research workshop on computational modelling [see my post on Can you trust your digital twins?on November 22nd, 2016]. It wasn’t my first trip to Taiwan [see my post entitled ‘Crash in Taipei: an engineer’s travelogue?’ on November 19th, 2014] but I visited a high school for the first time. I spent half a day meeting teachers and pupils at the Taipei European School. I gave a talk based on my post entitled ‘Happenstance, not engineering?’ [see my post on November 9th, 2016] to several groups of science pupils in an attempt to explain what engineers do. The reception was enthusiastic and we had some good question and answer sessions. It was a first for me to do this in any school and the first time in the memory of the teachers that a professional engineer had visited the school. A while ago I wrote about nurturing the spirit through the exchange of gifts in the form of knowledge [see my post entitled ‘Knowledge spheres’ on March 9th, 2016]. My spirits were lifted by talking to the pupils and maybe one or two of them will have been persuaded to think about becoming an engineer. We also exchanged material gifts so that I have a beautiful vase to stand on my shelf and remind me of an enjoyable visit and hopefully prompt me to go again. Lots of young people have no idea what engineers do and are looking for a career that will allow them to contribute to society, so they are surprised and excited when they realise engineering offers that opportunity. So, we should get out more and tell them about it.

Can you trust your digital twin?

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Author's digital twin?

Author’s digital twin?

There is about a 3% probability that you have a twin. About 32 in 1000 people are one of a pair of twins.  At the moment an even smaller number of us have a digital twin but this is the direction in which computational biomedicine is moving along with other fields.  For instance, soon all aircraft will have digital twins and most new nuclear power plants.  Digital twins are computational representations of individual members of a population, or fleet, in the case of aircraft and power plants.  For an engineering system, its computer-aided design (CAD) is the beginning of its twin, to which information is added from the quality assurance inspections before it leaves the factory and from non-destructive inspections during routine maintenance, as well as data acquired during service operations from health monitoring.  The result is an integrated model and database, which describes the condition and history of the system from conception to the present, that can be used to predict its response to anticipated changes in its environment, its remaining useful life or the impact of proposed modifications to its form and function. It is more challenging to create digital twins of ourselves because we don’t have original design drawings or direct access to the onboard health monitoring system but this is being worked on. However, digital twins are only useful if people believe in the behaviour or performance that they predict and are prepared to make decisions based on the predictions, in other words if the digital twins possess credibility.  Credibility appears to be like beauty because it is in eye of the beholder.  Most modellers believe that their models are both beautiful and credible, after all they are their ‘babies’, but unfortunately modellers are not usually the decision-makers who often have a different frame of reference and set of values.  In my group, one current line of research is to provide metrics and language that will assist in conveying confidence in the reliability of a digital twin to non-expert decision-makers and another is to create methodologies for evaluating the evidence prior to making a decision.  The approach is different depending on the extent to which the underlying models are principled, i.e. based on the laws of science, and can be tested using observations from the real world.  In practice, even with principled, testable models, a digital twin will never be an identical twin and hence there will always be some uncertainty so that decisions remain a matter of judgement based on a sound understanding of the best available evidence – so you are always likely to need advice from a friendly engineer   🙂

Sources:

De Lange, C., 2014, Meet your unborn child – before it’s conceived, New Scientist, 12 April 2014, p.8.

Glaessgen, E.H., & Stargel, D.S., 2012, The digital twin paradigm for future NASA and US Air Force vehicles, Proc 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference, AIAA paper 2012-2018, NF1676L-13293.

Patterson E.A., Feligiotti, M. & Hack, E., 2013, On the integration of validation, quality assurance and non-destructive evaluation, J. Strain Analysis, 48(1):48-59.

Patterson, E.A., Taylor, R.J. & Bankhead, M., 2016, A framework for an integrated nuclear digital environment, Progress in Nuclear Energy, 87:97-103.

Patterson EA & Whelan MP, 2016, A framework to establish credibility of computational models in biology, Progress in Biophysics & Molecular Biology, doi: 10.1016/j.pbiomolbio.2016.08.007.

Tuegel, E.J., 2012, The airframe digital twin: some challenges to realization, Proc 53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference.

Will it all be over soon?

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milkywayNASAAs you may have gathered from last week’s post [Man, the Rubbish-Maker on October 26th, 2016], I have been reading Italo Calvino’s Complete Cosmicomics.  In one story, ‘World Memory’ the director of a project to document the entire world memory in the ‘expectation of the imminent disappearance of life on Earth’ is explaining to his successor that ‘we have all been aware for some time that the Sun is halfway through its lifespan: however well things went, in four or five billion years everything would be over’.  The latter is one of the scientific conclusions around which Calvino weaves these short stories and this one put into perspective the concerns expressed by some of my students on both my undergraduate course and MOOC in thermodynamics the prospect of a cosmic heat death resulting from the inevitable consequences of the second law of thermodynamics [see my post ‘Cosmic Heat Death‘ on February 18th, 2015].  The second law requires ‘entropy of the universe to increase in all spontaneous processes’.   Entropy was defined by Rudolf Clausius about 160 years ago as the heat dissipated in a process divided by the temperature of the process.  The dissipated heat flows into random motion of molecules from which it is never recovered.  So, as William Thomson observed, this must eventually create a universe of uniform temperature – an equilibrium state corresponding to maximum entropy where nothing happens and life cannot exist.   Entropy has been increasing since the Big Bang about 13.5 billion years ago.  And as Calvino writes, the sun is about halfway through its life – it is expected to collapse into a white dwarf in 4 to 5 billion years when its supply of hydrogen runs out.  These are enormous timescales: the first human cultures appeared about 70,000 years ago [see my post ‘And then we discovered thermodynamics‘ on February 3rd, 2016]  and history would suggest that our civilization will disappear long before the sun expires or cosmic heat death occurs.  A more immediate existential threat is that our local production of entropy on Earth destroys the delicate balance of conditions that allows us to thrive on Earth.  See my post on Free Riders on April 6th, 2016 for thoughts on avoiding this threat.

Sources:

Italo Calvino, The Complete Cosmicomics, London: Penguin Books, 2002.

 

Revisiting closed systems in nature

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milkywayNASA

It is the beginning of the academic year and once again I am teaching introductory thermodynamics to engineering undergraduate students and my MOOC entitled ‘Energy: Thermodynamics in Everyday Life‘ is running in parallel.  Last week after my lecture on thermodynamic systems, a student approached me to ask whether the universe is a closed and isolated system.  It’s an interesting question and the answer is depends on the definition of universe.   In thermodynamics, we usually define a boundary to delineate the system of interest as everything inside the boundary and everything else are the surroundings.  The system and surroundings taken together are the universe (see my post ‘No beginning or end‘ on February 24th, 2016).  If the universe is defined as the system then there are no surroundings; hence the system cannot exchange energy or matter with anything which is the definition of a closed and isolated system.

Physicists often refer to the observable universe, or define the universe as everything we can observe.  We are aware that we cannot observe everything.  Hence, it is reasonable to suppose that the observable universe exchanges energy and matter with the unobservable space beyond it, in which case the observable universe is an open system.  We could also consider the concept that we are part of multiverse and our universe is only one of many, in which case it seems likely that is not isolated, i.e. it can exchange energy, and perhaps it is open, i.e. it can exchange both energy and matter with other parts of the multiverse.

This is not really thermodynamics in everyday life.  However, the occurrence of closed systems in nature appears to interest a lot of people to judge from the visits to my previous posts on this topic.  See ‘Closed Systems in Nature?‘ on  December 12th, 2012; Is Earth a closed system? Does it matter? on December 10th, 2014; and ‘No Closed Systems in Nature‘ on August 12th, 2015. For more about system boundaries, see my post entitled ‘Drawing Boundaries‘ on December 19th, 2012.