Scientists have designed a “skin” that senses when concrete structures are damaged

Image: Bittbox via Flickr, reproduced under creative commons.

Concrete is pretty great, isn’t it? It’s strong, it’s cheap, it’s easy to use. Let’s hear it for concrete!

On the downside, though, it’s also prone to cracking – if there are swift changes in temperature, for example, or if it’s bearing too much weight. Cracks in concrete structure are annoying at the best of times, but if said structure is holding, say, nuclear waste, they can also be disastrous.

So a team of scientists from North Carolina State University and the University of Eastern Finland have developed plans for a “skin” that would flag up cracks or damage to the concrete’s surface. Their idea involves installing electrodes at the edges of a structure, then applying electrically conductive copper paint across the concrete. The electrodes would emit a constant, low-level current across the surface of the painted “skin”, monitored by a computer. If the surface was weakened, cracked or damaged, the paint would become less conductive, and the computer would sense a change in the signal. You can even analyse the data to produce a map of the damage.

Here’s a cracked piece of concrete, alongside a computer rendering of the damage:

Image: Aku Seppänen.

So far, the researchers have only tried the method out on small, 1m long pieces of concrete, but they’re hoping to test on bigger areas. Dr Mohammad Pour Ghaz, one of the paper’s co-authors, said the team were keen to show the method could work on “real-world structures”.

 
 
 
 

Tweets of London: Which mayoral candidate is winning the social media battle?

Zac Goldsmith's campaign has denied rumours that he accidental overdosed on Skele-Gro as a child. Image: Getty.

In a blog last week we examined how what strategies the candidates to be mayor of London were employing in their tweeting – in terms of frequency, consistency and willingness to engage with the Twitter public.

This week, we’re take a look at how Twitter users have been responding to the candidate’s online campaigns.

By analysing the language Londoners use when they mention a candidate, we’ve categorised their tweets into “boos” and “cheers” – that is, people taking to Twitter to cheer on or support the candidates, or to call them out on failings and to hurl abuse. Over half of Londoners’ tweets which mentioned the candidates were emotionally charged in this way.


Digital boos and cheers

Unsurprisingly for anyone who has used twitter on a regular basis, “boos” aimed at candidates outnumber “cheers” four to one. Just 11 per cent of tweets sent at the candidates were cheers, compared to 44 per cent booing them. The remainder were neutral.

But who is Twitter most hostile towards? And who’s getting the most cheers?

When it comes to getting the digital thumbs up, Sian Berry leads the way, with 40 per cent of tweets mentioning her account cheering her on. Sadiq comes in second with 34 per cent, some way ahead of Zac Goldsmith’s 22 per cent. The relatively poor performance of the latter is surprising given the strong degree of consistency displayed in the use of the backzac2016  hashtag.

Least popular, perhaps surprisingly, is George Galloway – just 5 per cent of tweets mentioning George were classified as cheers, a real change in fortunes for one of the 2015 general election’s most popular politicians.

 

Most mentioned issues on Twitter

During the campaign, people have taken to Twitter to highlight the most pressing issues facing London. In total, around half of tweets mentioning the candidates were about housing, transport, health, Brexit and campaigning (that is, canvassing and campaign tactics).

It’s worth noting that despite being declared a “referendum on housing”, just 7 per cent of tweets to candidates have mentioned the issue.

The below table sets out the most frequently mentioned issues in tweets mentioning the Mayoral candidates.

Looking at these in more detail, we can show how which candidates are being referred to in relation to particular issues. The differences are striking:

As the table suggests, Caroline Pidgeon, the Liberal Democrat candidate, has been overwhelmingly featured in conversations about transport. The Green candidate, Sian Berry, has also been mentioned in relation to transport, although it is her housing policies which have received the most attention.

Sadiq Khan has received similar attention for his housing policies, with over half of tweets sent to him mentioning housing in London. Zac Goldsmith’s mentions also place housing as the most frequently mentioned issue by those tweeting him, although the margin is less clear.

Critics of Goldsmith have been vociferous in tying the Conservative candidate to his role in cutting disability benefit, which helps explain why the NHS and health are disproportionately represented in his mentions. The most retweeted tweet mentioning Goldsmith is in fact one referring to his position on disability benefit.

Brexit is a conversation tied to two candidates: UKIP’s Peter Whittle and Respect’s George Galloway. Both have shared a platform with Nigel Farage in the course of the campaign to discuss their pro-leave stance.

Who is winning the “boos and cheers” contest?

Applying the categorisation of ‘boos’ and cheers’ to each issue allows us to see which candidates are winning each topic. With the exception of Galloway, mentions of campaigning are generally positive, with Sian Berry, Caroline Pidgeon and Sadiq Khan performing particularly well. Notably, responses to Goldsmith’s campaign are more nuanced, perhaps indicative of the accusations that the candidate’s campaign against Sadiq Khan have been disingenuous at best – or downright Islamophobic at worst.

The trend reverses when we look at housing and transport – the two policy areas where the Mayor has the most power and influence. Responses are overwhelming negative, perhaps representing a tendency for supporters to attack the policies of rival candidates.

The policies of Caroline Pidgeon and Sian Berry have received the most support, with the proportion of tweets supporting Sadiq’s housing policy being twice that of Zac’s.  However, the Labour candidate has received serious stick online for his transport policies – most likely linked to his commitment to freeze Transport for London fares, arguably depriving the service of much needed investment.

With just under a week to go, our final blog will look in more detail at the two candidates, Zac Goldsmith and Sadiq Khan, looking at how they are targeting each other, and where online support for the two candidates is coming from.

On 4 May, we will also be hosting an event featuring highlights from our analysis by the authors, with a panel discussion including contributions from Jamie Bartlett (Director of CASM) and Ben Page (Director, Ipsos Mori). You can register your interest in attending here.

Kat Hanna is research manager at the Centre for London. Alex Krasodomski-Jones is a researcher at the Centre for Social Media Analysis at Demos.