Category Archives: Engineering

Digital twins that thrive in the real-world

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Windows of the Soul II [3D video art installation: http://www.haigallery.com/sonia-falcone/%5D

Digital twins are becoming ubiquitous in many areas of engineering [see ‘Can you trust your digital twin?‘ on November 23rd, 2016].  Although at the same time, the terminology is becoming blurred as digital shadows and digital models are treated as if they are synonymous with digital twins.  A digital model is a digitised replica of physical entity which lacks any automatic data exchange between the entity and its replica.  A digital shadow is the digital representation of a physical object with a one-way flow of information from the object to its representation.  But a digital twin is a functional representation with a live feedback loop to its counterpart in the real-world.  The feedback loop is based on a continuous update to the digital twin about the condition and performance of the physical entity based on data from sensors and on analysis from the digital twin about the performance of the physical entity.  This enables a digital twin to provide a service to many stakeholders.  For example, the users of a digital twin of an aircraft engine could include the manufacturer, the operator, the maintenance providers and the insurers.  These capabilities imply digital twins are themselves becoming products which exist in a digital context that might connect many digital products thus forming an integrated digital environment.  I wrote about integrated digital environments when they were a concept and the primary challenges were technical in nature [see ‘Enabling or disruptive technology for nuclear engineering?‘ on January 28th, 2015].  Many of these technical challenges have been resolved and the next set of challenges are economic and commercial ones associated with launching digital twins into global markets that lack adequate understanding, legislation, security, regulation or governance for digital products.  In collaboration with my colleagues at the Virtual Engineering Centre, we have recently published a white paper, entitled ‘Transforming digital twins into digital products that thrive in the real world‘ that reviews these issues and identifies the need to establish digital contexts that embrace the social, economic and technical requirements for the appropriate use of digital twins [see ‘Digital twins could put at risk what it means to be human‘ on November 18th, 2020].

Hot air is good for balloons but cold air is better for cars

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photograph of a MDI Airpod 2.0Cars that run on air might seem like a fairy tale or an April Fools story; but it is possible to use air as a medium for storing energy by compressing it or liquifying it at -196°C.  The MDI company in Luxembourg has been developing and building a compressed air engine which powers a small car, or Airpod 2.0 and a new industrial vehicle, the Air‘Volution.  When the compressed air is allowed to expand, the energy stored in it is released and can be used to power the vehicle.  The Airpod 2.0 weighs only 350 kg, has seats for two people, 400 litres of luggage space and an urban cycle range of 100 to 120 km at a top speed of 80 km/h.  So, it is an urban runabout with zero emissions and no requirement for lithium, nickel or cobalt for batteries but a limited range.  A couple of years ago I tasked an MSc student with a project to consider the practicalities of a car running on liquid air, based on the premise that it should be possible to store a higher density of energy in liquified air (about 290 kJ/litre) than in compressed air (about 100 kJ/litre).  His concept design used a rolling piston engine to power a family car capable of carrying 5 passengers and 346 litres of luggage over a 160 km.  So, his design carried a bigger payload for further than the Airpod 2.0; however, like the electric charging system described a few weeks ago [see ‘Innovative design too far ahead of the market’ on May 5th, 2021], the design never the left the drawing board.

Certainty is unattainable and near-certainty unaffordable

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The economists John Kay and Mervyn King assert in their book ‘Radical Uncertainty – decision-making beyond numbers‘ that ‘economic forecasting is necessarily harder than weather forecasting’ because the world of economics is non-stationary whereas the weather is governed by unchanging laws of nature. Kay and King observe that both central banks and meteorological offices have ‘to convey inescapable uncertainty to people who crave unavailable certainty’. In other words, the necessary assumptions and idealisations combined with the inaccuracies of the input data of both economic and meteorological models produce inevitable uncertainty in the predictions. However, people seeking to make decisions based on the predictions want certainty because it is very difficult to make choices when faced with uncertainty – it raises our psychological entropy [see ‘Psychological entropy increased by ineffective leaders‘ on February 10th, 2021].  Engineers face similar difficulties providing systems with inescapable uncertainties to people desiring unavailable certainty in terms of the reliability.  The second law of thermodynamics ensures that perfection is unattainable [see ‘Impossible perfection‘ on June 5th, 2013] and there will always be flaws of some description present in a system [see ‘Scattering electrons reveal dislocations in material structure‘ on November 11th, 2020].  Of course, we can expend more resources to eliminate flaws and increase the reliability of a system but the second law will always limit our success. Consequently, to finish where I started with a quote from Kay and King, ‘certainty is unattainable and the price of near-certainty unaffordable’ in both economics and engineering.

Innovative design too far ahead of the market?

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computer rendering of street with kerbstones fitted for chraging electric vehiclesThe forthcoming COP26 conference in Glasgow is generating much discussion about ambitions to achieve net zero carbon emissions. These ambitions tend to be articulated by national governments or corporate leaders and there is less attention paid to the details of achieving zero emissions at the mundane level of everyday life. For instance, how to recharge an electric car if you live in an apartment building or a terraced house without a designated parking space. About six years ago, I supervised an undergraduate engineering student who designed an induction pad integrated into a kerbstone for an electric vehicle.  The kerbstone looked the same as a conventional one, which it could replace, but was connected to the mains electricity supply under the pavement.  A primary coil was integrated into the kerbstone and a secondary coil was incorporated into the side skirt of the vehicle, which could be lowered towards the kerbstone when the vehicle was parked.  The energy transferred from the primary coil in the kerbstone to the secondary coil in the vehicle via a magnetic field that conformed to radiation safety limits for household appliances.  Payment for charging was via a passive RFID card that connected to an app on your mobile phone.  The student presented her design at the Future Powertrain Conference (FCP 2015)  where her poster won first prize and we discussed spinning out a company to develop, manufacture and market the design.  However, a blue-chip engineering company offered the student a good job and we decided that the design was probably ahead of its time so it has remained on the drawing board.  Our technopy, or technology entropy was too high, we were ahead of the rate of change in the marketplace and launching a new product in these conditions can be disastrous.  Maybe the market is catching up with our design?

For more on technopy see Handscombe RD and Patterson EA ‘The Entropy Vector: Connecting Science and Business‘, World Scientific, Singapore, 2004.