Tech Talk

Systems on the edge of failure sound funny. Ask the mechanic listening for the death-rattle of a dying U-joint or the doctor thumping a patient’s back.

And then there’s the deadly “click” of laminated surfaces coming unglued. Civil engineers have long used acoustic tests to find places where bridge and highway decks are delaminating, getting ready to flake off and fall away from their under layers. These test methods have been relatively slow, though, relying on carefully placed hammer blows, dropping steel ball bearings, or dragging heavy chains. The testers crawl down the road thump by painstaking thump at a top speed of less than two miles per hour.

Researchers at electronics and civil engineering departments of Brigham Young University have developed an elegantly simplified method for pounding the pavement, using the percussion of water droplets to find the weak spots.

They built a simple device (described in Non-Destructive Testing and Evaluation International) from off-the-shelf components: a water tank, a couple of lengths of 6-mm ID flexible tubing, a pump, a flow meter, a good array microphone, an acoustic sampling unit, and a reconfigurable I/O controller. The test rig dripped the droplets two meters onto a concrete floor (with a known weak spot from an earlier repair that didn’t quite take), and picked up the echoes from the impact with the microphone. (The microphone itself was raised well above the splash zone; a tubing “ear trumpet” put its ear to the ground in the splash zone and carried the noise back.)

Brian Mazzeo (he’s the one pouring water on the cracked floor in the photo), Anjali Patil, and W. Spencer Guthrie tested two droplet streams: a 22.5 milliliter-per-minute flow of 7-mm-diameter drops (weighing roughly 1/6 grams apiece) at about 2.3 drops per second, and a faster 94 milliliter-per-minute stream of smaller 3 mm droplets (just 1/70  grams each) at a “white noise” clatter of 110 or so impacts per second. The data—acoustic spectrograms of frequency over time—show clear, lower-frequency ghosting of echoes from buried structural discontinuities.

By adjusting the flow rate and drop volume, civil engineers may well be able to tune the device to reveal specific types of potential failures well before they occur. The method offers inexpensive components, easier clean-up (no BBs or buckshot to chase all over the roadway), and easier maintenance (no jammed hammers to re-set, no worn pivots to maintain).

There are a host of items to work out—finding the right drop-size and flow rates, of course, and coping with real-world wind and sub-freezing temperatures, just for starters—but it’s still fun to see something simple and useful improved by something even simpler.

The objective is to be able to drive a water-spraying test rig across a bridge or over a stretch of road at 25 or 30 miles per hour to detect structural flaws without long lane closures and traffic delays. And beyond that, water-impact acoustic testing could be expanded to quickly and cleanly detect spreading lesions in all sorts of materials, from airplane parts to fiberglass boat hulls.

Images: Brigham Young University

Don't expect to see Fukushima flounder on the menu anytime soon. Bottom-dwelling fish living near the coast of Fukushima prefecture are still contaminated with radioactive isotopes, according to a new analysis just published in the journal Science. The study suggests that the sea floor near Fukushima may be contaminated for decades to come. 

More than 19 months have passed since the Fukushima Dai-ichi nuclear power station lost power following a devastating offshore earthquake and tsunami, causing partial meltdowns in three of its reactors and a large release of radioactive materials into the air. Winds blew some of those radioactive materials out to sea, and rain carried them down into the ocean water. In addition, water used to cool the damaged reactors flowed from the coastal power plant into the ocean. In the weeks and months after the accident, plant owner TEPCO struggled to stop leaks of contaminated water into the sea and to create a closed loop for the cooling water. 

Ken Buesseler of Woods Hole Oceanographic Institution had previously studied radiation levels in the ocean waters near Fukushima, and has now turned his attention to fish. Buesseler analyzed data from Japan's fisheries agency, which has been testing fish and other sea life for radioactive isotopes since the accident. When Buesseler examined the data for fish off the coast of Fukushima, he found that 40 percent of bottom-dwelling fish (including flounder, skate, cod, halibut, and sole) had radiation levels that exceed the current safety standards in Japan. Surface-dwelling and open ocean fish didn't exceed those limits.

Buesseler told me that the most striking finding is that the radiation levels in these fish aren't going down. "I was struck by how they really haven’t changed over the last year," he said. He was looking specifically at the radioactive isotopes cesium-134 and cesium-137, both of which were released in the Fukushima Dai-ichi accident. "Since cesium doesn’t bioaccumulate to a significant degree, and in fact is lost when fish move to a less contaminated area, this implies that the cesium source is still there," he said. The bottom-dwelling fish are probably constantly re-contaminated by radioactive sediments layered on the seafloor, says Buesseler. And it may take decades for those sediments to be dispersed, and for the fishing area to be considered safe again. 

It's also very possible that the Fukushima Dai-ichi power station is still leaking radioactive water, says Buesseler. "It could be that they’re not recovering all that cooling water, there could be leaks in the basement," he says. "Even if they’re not putting new water out, the groundwater is still contaminated." 

TEPCO spokesman Yoshikazu Nagai says that the company has taken numerous actions to prevent further contamination of the ocean near the power plant. "We have covered the marine soil to prevent radioactive materials from being diffused into the ocean area near the power station and are currently in the process of building a water shielding wall to prevent groundwater flowing out of the power station site," he wrote in an email. That "water shielding wall" is a sunken barrier positioned between the reactor buildings and the coast.

Nagai wrote that TEPCO's ongoing monitoring of the ocean shows no increase in radiation levels. He did not directly respond when I asked whether TEPCO has information about leaks of contaminated water from the power station. 

Image: Ken Buesseler

My husband and I bought our first full-HD (1080P) TV set this weekend. Despite living in Silicon Valley and being immersed in technology, we’re not exactly early adopters. But we needed a new TV quickly (before the Sunday Giants game), so we made a fast shopping trip on Saturday and ended up with 1080P model. Personally, I see no difference between the 720P and 1080P resolutions in the 32-inch diagonal size we were in the market for, but my husband wanted “better” resolution, so we went for it.

He's happy with our new HDTV. So I don’t really have the heart to tell him that we’re about to fall behind the technology curve once again, because LG and Sony are both going to ship televisions with resolutions of 3840 by 2160 pixels in time for the holiday season. They had both been calling this resolution “4K”, but last week that moniker became dated when the Consumer Electronics Association (CEA) voted to tag this next generation of displays “Ultra High Definition”, or “UltraHD.” The CEA also announced that it expects to see a lot of product introductions in this resolution at the January 2013 Consumer Electronics Show.

These won’t be cheap. Sony’s 84-inch diagonal 4K TV (the company isn’t eager to embrace the UltraHD name) will cost about $25,000; LG’s model is a comparative bargain at about US $20 000.

What’s the point of UltraHD? In smaller screen sizes, there isn’t any; the technology will only be meaningful for extremely large TVs. And there’s not a lot to watch at home in this higher resolution. While movies for theaters are recorded in this higher resolution, so far, there have only been a few test broadcasts of television programming—for example, by the BBC during the Summer Olympics. So, for the time being they’ll be taking HD video signals and filling in the missing pixels by extrapolating from the existing ones.

Follow me on Twitter @TeklaPerry.

Photo: LG

Still basking in the Cerenkov glow of their Higgs boson papers, the folks at CERN (the European Organization for Nuclear Research) announced another international collaboration with a group equally famous for particle-acceleration experiments: Rovio, the Finnish company that launched a billion Angry Birds. (Rovio announced the billionth Angry Birds download last month.) Rovio and CERN will collaborate to bring modern physics into the Angry Birds Playground, yielding a learning program for elementary school-age kids.

“Modern physics has been around for 100 years, but it’s still a mystery to many people. Working together with Rovio, we can teach kids quantum physics by making it fun and easy to understand,” said CERN’s Head of Education, Rolf Landua, at an October Frankfurt Book Fair press event announcing the alliance.

I say, why should the physicists have all the fun?

Visions of sugar plums danced it my head (er, so to speak) and took the form of:

• Electrically charged birds that fly through magnetic fields to curve their trajectories and generate lightning bolts to fry evil swine.
• Spinning gyro-birds that twist and tumble when the pigs try to deflect them. (Note to self: Pseudotensors make the best toys.)
• Birds that diffract through double slits to mow down a whole phalanx of pigs in a hail of probability interference fringes.
• Birds with superposed states.
• Birds that tease Schroedinger’s cat.

When I started calculating that you could accelerate a six-ounce sparrow to three-quarters of the speed of light (and a relativistic mass of 9 ounces) if you could pull a surgical tubing slingshot out to 14 000 astronomical units…well, it was clear I was getting carried away. Fun calculation, limited game-play potential.

Clearly my ideas need a lot of work. While I continue to look for my battered paperback of George Gamow’s Mr. Tompkins in Wonderland ("Does one of the kids have it?" I thought late last night.), I'm hoping to find out what you think. What physical phenomena would you like to see in Angry Birds vs. the Higgs Boson (my title, not theirs)? CERN and Rovio are listening.

“We are planning to explore further possibilities to integrate a large amount of modern physics—in a playful and motivating way - into the various Rovio platforms,” CERN’s Landua told me via e-mail. “I would be really interested to see the proposals…most likely there would be many good ideas.”

I agree. I predict that you'll come up with amazing ideas—certainly be better than mine.

Over to you. If you’ve got an idea, please add a comment.

Like movie executives, hopeful entrepreneurs tend to describe their new companies in terms of successful ones that came before them. It’s not clear whether they do this because they’re hoping some of the magic pixie dust that turned a previous idea into gold will trickle down to them, or because they think an analogy is the best way to get the world’s attention, or because they didn’t have a original idea and are simply evolving an old one. But it’s so common it inspires parody, like youtube videos that pitch Pandora for cats, among other imagined technologies.

At this year’s DemoFall conference held earlier this month in Santa Clara, Calif., these mini-homages to successful startups were everywhere. There was OnCam, “the twitter of video chat;” Itography, “geocaching for shoes;” Flinja, the “Airbnb for college service providers” (college students who do freelance jobs); Omnicloud, “the Dropbox for apps;” Givit, one of several “Instagram for videos;” and Wiresurfer, the “Kayak for business telecom services.”

And then there was OrbitFront, a reviews site with a 14-year-old founder who decided one analogy was not enough and touted his startup as having “the community of Twitter, the expression of Youtube, and the profitability of Amazon.” 

Will any of these nascent companies turn into successful enterprises? It’s little early to tell, but the venture capitalists, analysts, and already-successful entrepreneurs critiquing the demos, while not so enthusiastic about geocaching for shoes, did seem to agree that the world is actually waiting for “Instagram for Video.” Today, while it’s easy enough to take videos with a mobile device, editing and sharing them isn't, and a company that takes away the pain and becomes a standard for video sharing could succeed. And while it’s not clear that any of the mobile video editing companies who presented their wares at DemoFall are going to replicate the sold-to-Facebook-for-$1-billion success of Instagram, that possibility is what keeps the startup energy flowing.

Follow me on Twitter @TeklaPerry.

Image: Author's mashup representing a geocaching Instagram for shoes.

Like so many others in the U.S., I was glued to the TV screen during this week’s presidential debate, even though I already have decided whom I’m voting for. My time, frankly, might have been better spent reading my ballot packet. Because I have yet to figure out how I’m going to vote in some of the local races. I’ve got the school board figured out, but haven’t tackled the governing board of the local community college district yet. Or chosen my candidates for my water district; I’m not entirely sure what a water district is. Selecting local candidates, these days, means pawing through the mailers arriving at my house, reading the local papers, and looking around at the yard signs of people I know I agree with on most issues to see how they are voting.

And indeed, looking at ads, reading reviews, and checking with friends is a reasonable way to make decisions—it’s how we decide what books to read and movies to watch. But today, we have another way to help us choose books and movies—recommenders, those computer programs, on websites like Amazon and Netflix, that watch our behavior and make suggestions based on their understanding of what we like and what people similar to us like.

The technology behind recommenders has been evolving quickly; the October issue of IEEE Spectrum reports on that evolution extensively in “Deconstructing Recommender Systems” by Joseph Konstan and John Riedl. And recommenders have starting being applied in areas beyond online shopping—helping university students identify courses, for example, and helping cell phone providers figure out which customers they are in danger of losing.

And, it turns out, as startup company ElectNext reported at DemoFall earlier this month; they are also useful in helping people make political choices.

OK, that sounds a little creepy at first glance—computer software that tells us how to vote? And it could be creepy if the company behind the software has an agenda. But ElectNext promises to stay non-partisan; it will never take advertising money or sell user data. Instead, it plans to sell itself as a service to news and other web sites interested in drawing traffic.

It starts by asking users to take a stand on ten issues and rate each one on whether or not it is important. Users don’t all see the same ten questions. After each question is answered, ElectNext’s recommenders determine which question to ask next. Then, based on the users' answers, the answers of people like them, and many of the other factors that book and movie recommenders consider, ElectNext will “suggest” candidates. ElectNext, like many good recommenders, is transparent; if a user wonders why a particular candidate is recommended, he can click through to an analysis of issues on which the user and the candidate are aligned and issues on which they differ.

In my test, the first ten issues didn’t get me any useful recommendations; my answers, it seemed, were all over the place. I took the option to look at more issues; going through four more seemed enough to allow ElectNext to find its recommendations. As ElectNext builds a wider and deeper database of user ratings, this process will likely become more efficient. The website has a few other glitches; for one, the only way to get back to the home page is to log out. But it has potential.

Between elections, ElectNext could track candidates and issues for users, sending an alert when a vote is coming up on an issue they care about, letting them know that it might be a good time to write some letters to their representatives.

Right now, ElectNext is focusing on national races; after November, the company plans to build its database of local candidates, using interest group ratings, campaign finance records to infer positions based on where a candidate’s support comes from, data points gathered by analyzing interviews, and data coming in from politicians themselves and ElectNext users. So for now, I'm going to have to figure out that water district election on my own.

To try out ElectNext, go to www.ElectNext.com.

This is the week for gazing up at the moon floating serenely in the night sky and imagining cataclysmic interplanetary collisions. Picture a Mars-sized planet slamming into the Earth about four-and-a-half billion years ago, injecting its iron core into our planet and sending a couple of quintillions of tons of vaporized mantle rock into orbit, where it forms a ring that re-condenses into the Man in the Moon.

Planetary scientists at the Washington University at St. Louis (WUSTL) and Scripps Institution of Oceanography have supplied a key piece of evidence supporting just that giant-impact scenario of lunar formation—continuing the evolution of a 1975 conference-room conjecture into the leading explanation of selenic cosmogony. (The 1975 date is a little artificial. The idea that the moon is an offspring of Earth has emerged many times over the centuries. The 1975 incarnation, though, sprang from the then-recent chemical analysis of Apollo moon rocks.)

Until now, supporting evidence has included orbital mechanics, lunar geology ("selenology," I guess), and crust chemistry, but one detail has been missing.

Yes, the angular momentum vectors of the Earth’s rotation and the moon’s orbit align closely, suggesting that Earth and moon were once part of a single spinning body. Yes, the entire lunar surface appears to have been molten at some fairly recent period, and its iron core is smaller than would have been expected if it had formed independently. And, yes, while rocks of the Earth, moon, and Mars seem to be drawn from the same primordial dust-ball, lunar rocks are relatively low in “moderately volatile” elements like manganese, sodium, potassium, zinc, sulfur and lead—as though a significant proportion of these elements had boiled off into space to be blown away by the solar wind.

If this geological distillation had taken place, however, we should be able to detect a skewing in the ratios of isotopes of these moderately volatile elements. The same wind that carried off little bit of the volatile elements should have carried off more atoms of these same elements’ light isotopes, leaving more of the heavy isotopes behind to gel into lunar rocks.

The researchers report (in Nature) that they have found exactly that: Moon rocks have consistently higher ratios of heavy zinc isotopes than do their cousins from Earth, Mars, or the asteroid belt. After an exhaustive analysis of lunar basalts (selected to reflect internal lunar composition), Martian meteorites, and igneous rocks from Earth, Randal C. Paniello, James M.D. Day, and Frederic Moynier have found the fingerprints of that early collision.

The measurements are exacting, because the differences in relative abundance ratios are small—about one part per thousand. But the moon rocks’ 0.07% to 0.17% excess of ⁶⁶Zn is consistent, distinct, and tightly clustered. Terran, Martian, and meteorite chondritic rock all have nearly identical ⁶⁶Zn/⁶⁴Zn ratios, differing only very slightly because volcanic processes produce small, local variations in heavy isotope concentrations. Moon rocks, on the other hand, stand away from the pack.

It may not be quite a smoking gun, but it welds another important supporting member into the giant-impact edifice.

Meanwhile, other scientists are also playing solar-system billiards.

Researchers at the Southwest Research Institute (SWRI) and Harvard University have shown how an even bigger impact might explain Earth/moon isotope ratios in a different way. And scientists at the University of California at Santa Cruz (UCSC) and the University of Bern suggest that Saturn’s giant moon, Titan, might also be the result of a massive impact event. (The two groups report their findings in Science.)

SWRI’s Robin Canup shows how a collision with an object even more massive than Mars might have produced a moon with chemical composition (especially oxygen composition) more like Earth’s; this model, though, produces an Earth-moon system that spins approximately twice as fast as we do. So the Harvard team of Matija Cuk and Sarah T. Stewart shows how gravitational interactions could have slowed that fast Earth to spin at the speed we see today.

And farther out in the solar system, suggest UCSC's Erik Asphaug and Bern's Andreas Reufer, Saturn’s giant moon, Titan, formed in its own consolidating smash-up, leaving shreds of its icy mantle scattered around in the form of Saturn’s minor moons. Titan is about twice the mass of Earth’s moon and a little bigger than the planet Mercury, with a highly eccentric orbit. Both its mass and eccentricity may, say Asphaug and Reufer, stem from the impacts that formed it. (The analysis is slated for publication in an upcoming issue of Icarus.)

Images: Planetary impact-- NASA/JPL-Caltech; lunar rock (cross-polarized light)—J. Day, Scripps Institution of Oceanography; protoplanet collision simulation—Southwest Research Institute.

Researchers have produced for the first time a three dimensional map of the underside of Antarctic sea ice, giving them a tool to measure the thickness of the ice in unprecedented detail. Accurate measurements of ice thickness are crucial for tracking the effects of climate change.

The scientists also measured the thickness of the snow and ice above the water using helicopters equipped with a scanning LiDAR (which uses light to image objects), high-resolution aerial photography, GPS, and a microwave radiometer. 

The combined data from above and below the ocean's surface allows researchers to produce an accurate measurement of the thickness of the ice—the holy grail of climate change tracking tools. The results also set a baseline to which researchers can compare changes in ice thickness over time, allowing them to better understand the effects of climate change. 

In the past, researchers have measured the thickness of Antarctic ice by taking drill line measurements or by observing the thickness of the ice while moving through it on a ship. Surface area is more easily measured, and has been for years using satellite images, but only offers limited clues to how much ice volume exists.

The inverted 3D map comes from a collaboration of 50 scientists from eight countries who are on a two-month voyage on Australia's research vessel Aurora Australis. The map is one project in a larger mission to investigate the relationship between sea ice environment and ocean ecosystems. The AUV, which launched from the Aurora, is operated in partnership with Woods Hole Oceanographic Institution based in Woods Hole, Massachusetts.

Photo: AUV team/Australian Antarctic Division

The exoplanet zoo just got a truly spectacular addition. Astronomers have found evidence for an Earth-mass planet in our own backyard, about 4.4 light years away in the Alpha Centauri system, the star system nearest to our own. 

The planet, which is at least 1.1 times the mass of the Earth, orbits Alpha Centauri B (α Cen B), one of two sun-like stars in the three-star system. With a year lasting just 3.2 days, the planet speeds around α Cen B in a scorching orbit, one that's far too close to be considered habitable. "If there are any inhabitants there, they're made of asbestos," SETI Institute astronomer Seth Shostak quipped in an interview with NPR. 

Still, the discovery has astronomers excited because low-mass planets often seem to come in groups. It may be that there is an Earth-like planet just waiting to be found in α Cen B's 'habitable zone', with temperatures in just the right range to support the presence of liquid water and life as we know it. 

That doesn't mean such a planet will be easy to find. This discovery was already pushing the limits of existing instruments. Xavier Dumusque, a Ph.D. student affiliated with the Geneva Observatory, and colleagues found the planet by scouring starlight coming from α Cen B using the High Accuracy Radial velocity Planet Searcher (HARPS) instrument, an ultra-precise spectrograph mounted on a 3.6-meter telescope at the La Silla Observatory in Chile. HARPS is designed to pick up tiny shifts in spectral lines that arise when planets tug on their host stars and cause them to move back and forth along the line of sight with Earth. 

Finding the stellar wobbles created by the planet around α Cen B required detailed modeling of stellar activity. Although α Cen B is a relatively calm star, it still has weather that can mask the presence of planets. In the end, the team uncovered a signal that, according to an article accompanying the team's paper, is just one third as strong as α Cen B's stellar activity. The signal is puny compared to previous finds, corresponding to stellar motion of just 50 centimeters per second, or about as fast as a baby crawls, according to a press release put out by the European Southern Observatory. That's about 1% the speed generated by the tug of 51 Peg b, a planet about half the mass of Jupiter that was discovered in 1995 (it was the first to be found orbiting an ordinary star). 

"The Geneva team has done something very difficult," says Debra Fischer, an astronomy professor at Yale University. "There is not a more exciting result for an individual star, even with the long line of spectacular results from the last 2 decades." Fischer has been conducting a search for planets around α Cen B using a new detector on the 1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile and says her team is well poised to follow-up on the HARPS measurements.

Finding habitable planets around α Cen B could be trickier. At a press conference on Tuesday, Dumusque said that, at its current sensitivity, HARPS could turn up a planet in the habitable zone of α Cen B with a mass as low as four times the mass of Earth. Finding a true Earth twin, an Earth-mass planet on an Earth-like orbit, would require measuring stellar motions of just 9 centimeters per second, says Nature News.

There is some hope that we'll get there. Astronomers are testing out new laser-based calibration systems that could help boost the sensitivity of HARPS and other such instruments by a factor of 10 (although astronomers will still have to contend with stellar activity). And there are other ways to detect planets. If the alignment is right, we could potentially see α Cen B planets as they pass in front of the star in the course of their orbit, temporarily blocking out a fraction of the light that reaches Earth. 

Either way, maybe it's time to start contemplating a mission to Alpha Centauri to see what there is to find. We'll probably want something a bit speedier than our interstellar pioneer, Voyager 1. If the spacecraft were headed in that direction, it would take more than 70,000 years to reach the system.

(Image: G. Hüdepohl/ESO)

A new type of ocean power generator could harvest the steady, reliable energy of deep ocean currents, and a group of companies are working together to place the first 1-megawatt system on the seafloor. The companies are currently raising money for the demonstration project and say they're investigating R&D funding from the U.S. Navy and the Department of Energy. 

The grid connections and system software are being designed by Eaton Corporation, a power management company with experience in linking renewable energy sources like wind and solar farms to the grid. The 1-MW turbine will come from Triton, a Florida-based company that primarily builds deep-ocean subs. Eaton representatives say the 1-MW demonstration project could easily be built up to a utility-scale current farm by adding more turbines. 

Deep ocean currents are generated by differences in the ocean's salinity and temperature around the continents. They run at a constant speed of about 3 to 5 knots (5.5 to 9 kilometers per hour), according to Eaton's Department of Defense account development manager Jim Spaulding. "You’d be amazed at how steady-state these deep ocean currents are," Spaulding told me. "That’s the appeal: It’s very, very consistent." 

The consortium hasn't picked out a spot yet for its demo, but Spaulding mentioned the waters off the coast of Florida as one attractive option. There, strong currents can be found within a couple of miles from shore and at relatively easy-to-reach depths of 30 to 150 meters, he said. Eventually, Eaton plans to build systems at depths of 300 to 500 meters. 

While the ocean energy industry is in its infancy, there's been a lot of excitement in recent years over new turbine technologies and demonstration projects. In the United States, the first tidal station began providing power to the Maine grid in September, and a wave power project is intended for Oregon's waters (although the installation of the wave power turbine was recently postponed until spring 2013). Outside the United States, companies like Pelamis Wave Power and OpenHydro are pursuing commercial-scale wave and tidal power stations, respectively.

Image: Triton Energy Systems, LLC