Don’t get your wires crossed

We are all familiar with requests when flying not to use mobile phones or computers. But how can designers assess the safety implications when different electronic systems interact in a very complex environment such as an aircraft?

This question was addressed by KTN project partners at BAE Systems, the Motor Industry Research Association and the University of Nottingham. The technical name for such issues is Electromagnetic Compatibility (EMC), meaning the ability of different electronic circuits to operate correctly in the presence of their neighbours.

Electronic systems are now all around us: at home, at work and when travelling. All equipment has to be tested for EMC — and in some contexts this is a critical issue for safety purposes — but physical EMC testing is both expensive and time-consuming. Computational EMC testing is therefore an attractive alternative. The challenge then is that simple computational models lack accuracy and full computational electromagnetic simulations are not feasible if the problem is too large. Led by Dr Richard Tew and Prof Christos Christopoulos, postdoctoral researchers Catherine Tully and Ian Thompson have developed methods that help provide an efficient way to capture complex detail and variations in the system components. The results of their work will be incorporated as new elements in EMC software.

“This will enable engineers to assess how good their design is, make modifications throughout the design cycle, and so mitigate the risk of EMC test failure. If you fail the final EMC test and need to modify the product, costs can be huge if the start of production is delayed.” - Liz Davenport, BAE Systems.

It takes all sorts

Sortex Ltd, now part of the Buhler Group, is a world leader in the optical sorting of particulate foodstuffs such as rice, beans and dried fruit.

Its sorters combine high accuracy with throughputs of up to 36 tons/hour. Sorted product commands a considerably higher price than unsorted product. Accuracy of sorting reduces waste and increases profit, and so is a fundamental issue across the food industry.

The sorting methodology comprises, first, optical imaging, then pattern recognition, and finally the activation of air jets to remove unwanted product. These jets have a velocity of 20 metres per second and fire in bursts of up to 300 cycles per second. Under the guidance of Prof Frank Smith at University College London, postgraduate KTN Associate Paul Westwood has shown how careful mathematical modelling aids the design of the jet nozzles. The key issue is the interference between adjacent nozzles and consequent lack of sharpness of the jet boundaries. By modelling this interference, we can understand how the nozzle geometry determines the maximum sorting accuracy that can be achieved. This information is crucial when designing new nozzles.

“Such mathematical research has a number of benefits: we understand the fundamental physics of the sorting process; we understand the design trade-offs; we improve our next generation developments and we tend not to overdesign … we add design cost where we know we will gain performance benefits.” - Mark Honeywood, formerly Head of R&D, Sortex.

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