Engineering News (May 2018)

UK researchers literally squeeze more power from solar cells

Researchers led by Professor Marin Alexe at Warwick University, have demonstrated a way to produce more energy using Photovoltaic (PV) Solar Panels. The short explanation is that by deforming the crystals in the semiconductor materials by pressing on them – a process that utilises the PV’s anisotrophic properties –  the efficiency of the PV panel can be increased.

In traditional solar cells, that use the p and n  junction system, light is absorbed by the cell and the charge carriers are sent off in different directions along the semiconductors producing a current and a voltage. The new solar cells, using something Prof Alexe describes as a ‘Flexo-photovoltaic effect’, could boost the energy efficiency levels of the traditional p and n junction system upwards from around 26%, by causing what is essentially an asymmetry within the semi-conductors. In the ‘Flexo-photovoltaic cells system’, distorting the p n junctions by pressing on or shaping the semi-conductor introduces an asymmetry in the core, meaning the charge carriers are spontaneously split producing a higher current and voltage and thus a higher efficiency level.

The combination of the ‘traditional p and n junction’ structure and the introduction of the ‘pressing and shaping’ method (using the concept of the ‘bulk photovoltaic effect’) has been described as having the potential to increase the efficiency of commercial solar cells in years to come.

Graphene’s on a roll now

Graphene sheets are currently produced in small batches and have uses as membranes in desalination and biological separation processes. The hope is that one day, graphene membranes can be used in a more commercially viable way with further applications.

Researchers at MIT have created a technique for the fast manufacture of high quality, homogenous, and large continuous sheets of graphene. The graphene must be seamless and in quantities large enough to provide an effective membrane, sometimes on an industrial scale, with a reliable high performance level. Researchers have developed the manufacturing technique using a roll-to-roll spooling system, that ran successfully for almost 4 hours and created around 10 metres of continuous graphene. The speeds of the spooling and the amounts of methane and hydrogen gas used to manufacture the sheets can be manipulated to produce graphene sheets with slightly different properties as required.

Robot blobs now a reality

Research teams collaborating under the umbrella of the University of Houston have created a soft robot. This in itself is not new, but what is ground-breaking about this robot is that it is capable of sensing and adapting to its environment. The robot has amazing potential in the fields of surgery and search and rescue operations, after disasters and on battlefields; with the robots being used for applications such as ‘keyhole’ type surgery, and searching in rubble by entering fallen structures through small cracks.

The inspiration for the robot was the movement of the caterpillar and by using ultra-thin sensing electronics, actuators, temperature sensors and artificial muscles, these systems combine to make this highly flexible and adaptable robot. Later robots can be fitted with other sensors as required.

Doomwatch scenario comes true as Plastic Eater discovered

As our high streets and eateries discontinue the use of straws, cut down on packaging and charge for plastic bags, the issue of plastic pollution is certainly in prominence at the moment. The current practices of recycling plastics are not enough on their own and the use of plastics is having devastating physical effects on marine life in particular. The oceans are littered with huge flotillas of plastic waste.

Teams at the University of Portsmouth and the National Renewable Energy Laboratory (NREL) in the US have ‘accidentally’ created a synthetic PETase enzyme that breaks down PET (Polyethylene Terephalate) plastics. The synthetic PETase was engineered after researchers were studying a natural PETase that had naturally evolved in a Japanese recycling centre to discover its 3D structure and its mode of action. They took the natural PETase, and increased the size of the protein’s active site to enable the enzyme to digest more PET molecules at one time.

PET plastics can last for hundreds of years in the environment, so this is a great first step. Researchers are now using the techniques involved in protein engineering to improve the PETase structure further to work on larger volumes of substrate. This scenario was predicted nearly fifty years ago and brought to the fore in the early seventies by the BBC television science fiction series Doomwatch, when a plastic eating virus was discovered.

Maximising a small plot in London

Space in London is scarce and the needs of the city are burdensome. So, a more creative use of space is needed to meet the needs of all stakeholders, whilst ensuring environmental sustainability at a cost that is not prohibitive.

One such scheme that is currently under construction and meets many of these needs is The Dudley House Project in Westminster, London. The site previously contained council-owned housing, a public house, a church, offices and a café. The main contractors, Willmott Dixon, are working for Westminster City Council to produce a new mixed use development on the 28,000 sqft site in the Paddington Basin.  The contractors and architects, Child Graddon Lewis, have worked closely with the council, stakeholders and Highways England to plan the construction of a 22-storey residential tower, a 7-storey residential tower, a 4-form entry boys school, a church and a small scale retail space. In light of the Grenfell Tower tragedy, the cladding will be a lightweight terracotta, as stipulated by the planners.

The southern section of the plot will contain an 840-pupil school, providing a much needed permanent home for The Marylebone School for Boys. With no room for playing fields or a games space at ground level, the school will have a netted area on the roof for outside space. There is also a central atrium which will provide light and make most of the classrooms dual aspect.

The school and the re-provision of the Assembly of God Church space has been designed and will be built to achieve a BREEAM rating of ‘Very Good’, and the residential units are anticipated to achieve a Level 4 on the Code for Sustainable Housing. It has been calculated that the centralised CHP boiler installation and the use of PV’s will deliver as much as a 35% improvement on the maximum CO₂ emissions. The buildings have been designed to ensure low maintenance costs both internally and externally.

The constraints of the site are huge as it is being constructed i a small area surrounded by other buildings (both residential and commercial). Willmott Dixon are implementing the scheme in accordance with BIM Level 2, coupled with careful planning of deliveries of materials using the ‘Just In Time’ approach, and the removal of waste and plant to ensure the most efficient build and the least disruption possible in this busy area. Slip form concrete structures are helping to speed up the build time, whilst masts are used instead of scaffolding by and minimising so-called ‘wet trades’, are all  helping further with the space restrictions.

The build is due to be completed in May 2019 and many of the features in The Dudley House Project are likely to be repeated throughout London.

Not bad for an old bird

The 1941 WWII de Havilland Mosquito fighter bomber has been awarded an honourable Engineering Heritage Award for its ground-breaking fused complex design that we still see used today.

The aircraft was known as one of the fastest aircraft when it was first introduced to operational service in 1941. The presentation took place on Sunday, 1st April at the ceremony based at the De Havilland Aircraft Museum in Hertfordshire.

The two-seated unarmed light bomber was known for its high fasts flying manoeuvres was using throughout the Second World War to fly swiftly above territory that was occupied by the enemy was built using wooden components with its overall design remit focussing on speed and long flight range.

The aircraft boasted amalgamated precision packaging with aerodynamic shapes, high wing loading (at the time implementing a revolutionary reduction in wing area), and reaching high speeds with additional power from the two-supercharged liquid-cooled Rolls Royce V-12 Merlin engines.

Over the course of time, the Mosquito evolved, seeing some 30 separate prototype iterations that lead to its final shape which proved its excellence as a multi-purpose aircraft.  The 1948 de Havilland DH.98 Mosquito prototype had the ability to reach maximum speeds of 437 mph at an altitude of 29,000 feet.

The de Havilland DH.98 Mosquito Prototype had been the 117th recipient in line to win the award, preceding the E-Type Jaguar, Concorde and Alan Turing’s Bombe, all of which have also been awarded this prestigious award. The de Havilland however is amongst many previous aircraft related winners, which have included such aviation luminaries as the Short SC1 VTOL, an aircraft which had a vast  influence on future aeroplane design, the Rolls-Royce RB211 engine and the Vulcan Bomber XH558, known as the archetypal “last airworthy” member of the RAF’s V-bombing taskforce.

With the Mosquito’s structure being made from wood meant that the aircraft was easy to repair, and due to the war effort, furniture and piano factories based in England, Canada and Australia were utilised in the building of the aircraft. The aircraft was equally successful with its aerodynamics, and was able to fly higher than any aircraft due to the absence of heavy weaponry, indeed, many of its features were incorporated into the early jet fighters, such as the Hunter, the Canberra and V-bombers, such as the Vampire (pictured below).

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Engineering News – April 2018

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