Technology Trending: Solar railways, brain inspired computing, propellors for e-planes

Solar PV to ‘carpet’ railway tracks, brain-inspired computing for more energy efficient devices and optimised propellor design to make future electric aircraft quieter are in this week’s technology radar.

Solar to carpet railways

With pressures on land availability for solar PV and lots of open space on railways, the Swiss start-up Sun-Ways has come up with the idea of ‘carpetting’ the space between the railway tracks with PV panels.

Although not the first to the concept – Germany’s Deutsche Bahn and the British company Bankset Energy have been testing solar cells attached to sleepers in railways in Saxony – Sun-Ways claim to be the first with a patented system for rapid installation and mechanical removal both to facilitate the work of installers but also to allow for necessary railway maintenance.

With a special train travelling along the rails, the panels can be laid and locked in place as it goes, just like “the unrolling of a carpet”, the company is quoted as saying.

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Sun-Ways suggests three ways to use the renewable electricity produced – injected into the railway company’s LV network to supply infrastructure such as switches and signalling, injected into the electricity network of the nearest DSO or injected into the traction energy network that supplies the locomotives, for which latter initiatives are underway in Switzerland.

Likewise trains can carry a cylindrical brush for cleaning the panels as they pass over them.

Subject to final approval Sun-Ways expects to pilot its PV system near Buttes station in the west of Switzerland in May.

Brain-inspired computing for more energy efficient devices

The human brain is highly energy efficient, able in computing terms to perform the equivalent of an exaflop mathematical operations per second with just 20W of power. In comparison, one of the most powerful supercomputers in the world, the Oak Ridge Frontier, recently demonstrated exaflop computing but needed 20MW – a million times more power – to achieve this feat.

With this background, a group of researchers at the US National Institute of Standards and Technology are looking to the brain as a guide in developing a powerful yet energy efficient computer circuit design.

The challenge, the researchers say, is that energy efficiency has emerged as the predominant factor limiting the creation of more powerful computer chips. The approach being pursued by the researchers is what is dubbed ‘race logic’, in which signals race against each other with the timing telling something about the solution to the problem.

At a practical level an example would be barn owls, which have been verified to use the difference in the arrival times of a sound to each ear to locate their prey.

In computing terms, race logic is about reducing the activity in the circuits. In conventional digital computers problems are solved by sending bits of information – 0s and 1s – on wires through a circuit. During circuit operation, bits regularly flip their values from 0 to 1 and vice versa, with each bit flip consuming energy. Race logic reduces the activity by encoding information in the timing of those bit flips.

The researchers are exploring mathematical techniques and practical technologies to make this concept even more efficient.

Propellor design for future electric aircraft

Electric planes of the future will be much quieter than their current counterparts – except for the noise of the rotating propellors, which could be obtrusive both for passengers on the planes and for those on the ground.

Considering this fact, and that the initial main focus of e-aviation will be on short-haul national and regional propellor driven aircraft, researchers at Chalmers University of Technology in Sweden have been exploring the noise that occurs at the tip of the propeller blades – the ‘tip vortices’ – and report being able to fully understand its role in relation to other noise sources generated by the blades.

Out of this has emerged a propeller design method adjusting a range of parameters, such as pitch angle, chord length and number of blades.

What the researchers found is that the more blades a propeller has, the lower the noise emissions, but also the efficiency and thus the range of the plane reduces.

“Modern aircraft propellers usually have two to four blades, but we’ve found that by using six blades designed using our optimisation framework, you can develop a propeller that’s both relatively efficient and quiet,” says Hua-Dong Yao, associate professor and researcher in fluid dynamics and marine technology at Chalmers University.

He explains that the propeller achieves a noise reduction of up to 5-8 dBA with only a 3.5% thrust penalty, compared to a propeller with three blades.

“That’s comparable to the noise reduction of someone going from speaking in a normal conversation voice to the sound you would perceive in a quiet room.”