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Submission + - echolocation by smartphone possible. batman phones all around! (ieee.org)

Submitted by jehan60188
jehan60188 writes: FTA:

Submarines, bats, and even humans can echolocate, but they need high-end acoustic gear, brainpower, or training in order to do it. Now electrical engineer Ivan Dokmani, of the École Polytechnique Fédérale de Lausanne (EPFL), in Switzerland, could bring that capability to smartphones. He has used echolocation combined with a simple algorithm and off-the-shelf microphones to map part of a complex structure—the Lausanne Cathedral. Used in reverse, this kind of technology could one day help smartphones find their location inside buildings.

Echolocation at its most basic consists of sending a sound toward an item of interest and timing its return. If you know the medium, you also know how fast it will carry the sound. Solve a simple equation and you have the distance to the item.

But mapping even the simplest room, let alone a cathedral, is more complex. The first sound reflects from all the room’s surfaces, flooding the listener with signals from many directions. Even after passing the microphone the first time, those first sound waves can reflect on opposing walls and return to the microphone a second time, adding secondary reflections to the already confusing signal. “You need somehow a way to tell, ‘This group of echoes corresponds to one wall, and another group of echoes corresponds to another wall,’ ” Dokmani says.

Some solutions involve sending sound from multiple known locations at different times. Other solutions involve using multiple microphones. Dokmani, who says he has a taste for simplicity, once tried to calculate a hypothetical room’s geometry using just one sound source and one microphone [PDF]. This system worked on paper for some kinds of rooms in noiseless environments, but in the real world, noise is everywhere. “Maybe you’ll have some spurious spikes in your signal,” Dokmani says, “so you also need a way to discard these.”

Dokmani’s method, published online this week in the Proceedings of the National Academy of Sciences, uses a mathematical tool called a Euclidean distance matrix, which helps sort the reflected sounds along a timeline. But he conceded a point to complexity and used multiple microphones—although only one sound source.

Electrical engineering researcher Flavio P. Ribeiro, of Microsoft’s Applied Sciences Group, in Redmond, Wash., calls this application of Euclidean distance matrices “useful” but notes that Dokmani’s algorithm assumes tidier environments than exist in the real world, such as rooms with no furniture or other clutter that might complicate the sound signal. Such clutter creates “sound shadows” that would require more computing power to untangle.

Other algorithms, including one created by electrical engineer Sakari Tervo of Aalto University, in Finland, and a colleague, seek to reconstruct a room’s geometry even in the absence of some of the initial sound reflections, although these algorithms rely on multiple microphones. Dokmani’s latest system assumes he has captured all the first reflections before he can filter out the secondary reflections and noise.

Tervo also worries that Dokmani’s algorithm will not translate to more complex settings. In their paper, Dokmani and his colleagues note that their map of the cathedral is imperfect due to reflections from figurines, columns, and curved surfaces. They were unable to distinguish between some of the smaller walls and the secondary reflections from bigger walls, he says. They achieved much better accuracy when they mapped a simple classroom with a fifth wall made of stacked tables.

Even so, the experiments inspired Dokmani to explore hiring a developer who could help create smartphone applications using his algorithm. In a room with known dimensions, a pair of sound-emitting devices might be able to calculate their positions in the room, he suggests. The algorithm might also help improve teleconferencing sound quality. Electrical engineer Fabio Antonacci at Politecnico di Milano, in Italy, says he and others aim to improve teleconferencing too. They presented a paper last year in which they tried to identify sound sources at multiple locations in order to focus the listening devices on all of them at once, in much the same way that recent experimental cameras allow users to focus on light images at multiple depths.

Achieving those goals will take “smarter algorithms,” Dokmani says, but after this experiment, he is optimistic: “It is kind of surprising that you can do it with so little infrastructure.”

No word yet on funding from Wayne industries

Submission + - Automakers meet rules with 'compliance cars' (asme.org)

Submitted by jehan60188
jehan60188 writes: FTA:

Automakers are in the uncomfortable position of building mostly at a loss a class of small electric cars that garner a lot of attention but few sales just to satisfy rules imposed by one state, California.

As a result, they've acquired the name "compliance cars."

They include electric versions of such familiar models as the Chevrolet Spark, Honda Fit and Toyota RAV4.

Most are being produced primarily or solely to meet California's mandate that large automakers sell a percentage of zero-emission cars in order to sell traditional cars in the state. Hybrids and natural gas cars aren't considered good enough, and hydrogen fuel-cell cars are still a ways off, so battery cars are the quickest way to comply.

Though automakers have held splashy unveilings of these electrics, they often are selling by the hundreds in an industry where tens of thousands determine profitability.

Limiting losses on the cars, not making a profit, has become the carmakers' initial goal. The state requires them not just to make but to sell the cars, and that has meant taking losses to bring down sale or lease prices on the relatively pricey cars to move them.

Last month, Chrysler Group CEO Sergio Marchionne said his company would limit production of the electric Fiat 500e because it will lose $10,000 on each. "Doing that on a large scale would be masochism to the extreme," he said.

The Fiat 500e, at $32,500 before subsidies, is almost twice the price of the base model of a conventional base Fiat 500, but the company has discount-lease and other plans to add to government subsides and cut the final cost.

Like many of the other such cars, the 500e will be sold only in California when it rolls out this summer.

The California rules apply to automakers that sell at least 60,000 vehicles a year in the state, which means the Detroit makers, plus Toyota, Honda and Nissan.

Analisa Bevan, sustainable-technology chief for California's Air Resources Board, says 10 other states also will adopt California's zero-emission mandate.

Hybrids, CNG cars and clean-burning gas engines don't count. "They don't get us far enough" to meet air quality and climate-change goals like electrics, she says.

The compliance cars stand in contrast to the electric Nissan Leaf or Tesla Model S, which are being promoted nationwide with the goal of commercial success.

Some automakers are trying to straddle the line. Ford says, for instance, that its $39,200 Focus electric is being sold at select dealers in all states except Wyoming and West Virginia. Even at that, Ford sold 566 through April this year, compared with 84,455 conventional Focuses.

A service of YellowBrix, Inc.

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