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Thursday, April 4, 2013
Wednesday, April 3, 2013
Ionic thrusters generate efficient propulsion in air
Apr. 3, 2013 ? Thrusters powered by ionic wind may be an efficient alternative to conventional atmospheric propulsion technologies. When a current passes between two electrodes -- one thinner than the other -- it creates a wind in the air between. If enough voltage is applied, the resulting wind can produce a thrust without the help of motors or fuel.
This phenomenon, called electrohydrodynamic thrust -- or, more colloquially, "ionic wind" -- was first identified in the 1960s. Since then, ionic wind has largely been limited to science-fair projects and basement experiments; hobbyists have posted hundreds of how-to videos on building "ionocrafts" -- lightweight vehicles made of balsa wood, aluminum foil and wire -- that lift off and hover with increased voltage.
Despite this wealth of hobbyist information, there have been few rigorous studies of ionic wind as a viable propulsion system. Some researchers have theorized that ionic thrusters, if used as jet propulsion, would be extremely inefficient, requiring massive amounts of electricity to produce enough thrust to propel a vehicle.
Now researchers at MIT have run their own experiments and found that ionic thrusters may be a far more efficient source of propulsion than conventional jet engines. In their experiments, they found that ionic wind produces 110 newtons of thrust per kilowatt, compared with a jet engine's 2 newtons per kilowatt. The team has published its results in the Proceedings of the Royal Society.
Steven Barrett, an assistant professor of aeronautics and astronautics at MIT, envisions that ionic wind may be used as a propulsion system for small, lightweight aircraft. In addition to their relatively high efficiency, ionic thrusters are silent, and invisible in infrared, as they give off no heat -- ideal traits, he says, for a surveillance vehicle.
"You could imagine all sorts of military or security benefits to having a silent propulsion system with no infrared signature," says Barrett, who co-authored the paper with graduate student Kento Masuyama.
Shooting the gap
A basic ionic thruster consists of three parts: a very thin copper electrode, called an emitter; a thicker tube of aluminum, known as a collector; and the air gap in between. A lightweight frame typically supports the wires, which connect to an electrical power source. As voltage is applied, the field gradient strips away electrons from nearby air molecules. These newly ionized molecules are strongly repelled by the corona wire, and strongly attracted to the collector. As this cloud of ions moves toward the collector, it collides with surrounding neutral air molecules, pushing them along and creating a wind, or thrust.
To measure an ion thruster's efficiency, Barrett and Masuyama built a similarly simple setup, and hung the contraption under a suspended digital scale. They applied tens of thousands of volts, creating enough current draw to power an incandescent light bulb. They altered the distance between the electrodes, and recorded the thrust as the device lifted off the ground. Barrett says that the device was most efficient at producing lower thrust -- a desirable, albeit counterintuitive, result.
"It's kind of surprising, but if you have a high-velocity jet, you leave in your wake a load of wasted kinetic energy," Barrett explains. "So you want as low-velocity a jet as you can, while still producing enough thrust." He adds that an ionic wind is a good way to produce a low-velocity jet over a large area.
Getting to liftoff
Barrett acknowledges that there is one big obstacle to ionic wind propulsion: thrust density, or the amount of thrust produced per given area. Ionic thrusters depend on the wind produced between electrodes; the larger the space between electrodes, the stronger the thrust produced. That means lifting a small aircraft and its electrical power supply would require a very large air gap. Barrett envisions that electrodynamic thrusters for aircraft -- if they worked -- would encompass the entire vehicle.
Another drawback is the voltage needed to get a vehicle off the ground: Small, lightweight balsa models require several kilovolts. Barrett estimates a small craft, with onboard instrumentation and a power supply, would need hundreds or thousands of kilovolts.
"The voltages could get enormous," Barrett says. "But I think that's a challenge that's probably solvable." For example, he says power might be supplied by lightweight solar panels or fuel cells. Barrett says ionic thrusters might also prove useful in quieter cooling systems for laptops.
"Efficiency is probably the number one thing overall that drives aircraft design," Barrett says. "[Ionic thrusters] are viable insofar as they are efficient. There are still unanswered questions, but because they seem so efficient, it's definitely worth investigating further."
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The above story is reprinted from materials provided by Massachusetts Institute of Technology. The original article was written by Jennifer Chu.
Note: Materials may be edited for content and length. For further information, please contact the source cited above.
Journal Reference:
- K. Masuyama, S. R. H. Barrett. On the performance of electrohydrodynamic propulsion. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2013; 469 (2154): 20120623 DOI: 10.1098/rspa.2012.0623
Note: If no author is given, the source is cited instead.
Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.
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High-skilled visa requests likely to exceed supply
WASHINGTON (AP) ? The Homeland Security Department expects applications for high-skilled immigration visas to outpace the available supply in a matter of days, one of the fastest runs on the much-sought-after work permits in years and a sign of continued economic recovery amid new hiring by U.S. technology companies.
The urgent race for such visas ? highly desired by Microsoft, Apple, Google and other leading technology companies ? coincides with congressional plans to increase the number available to tech-savvy foreigners.
The race to secure one of the 85,000 so-called H-1B visas available for the 2014 budget year started Monday and requests will be accepted through at least Friday. If petitions outpace the availability in the first week, U.S. Citizenship and Immigration Services ? for the first time since 2008 ? will use a lottery to pick which companies get visas to award to prospective employees.
"It will be a frenzy, because the cap ... is nowhere near high enough to meet demand," said Robert Holleyman, president and CEO of the Software Alliance, a trade group for technology companies.
Citizenship and Immigration Services spokesman Christopher Bentley said the agency won't know for certain whether a lottery is necessary until next week.
"We just won't know until we answer the mail each day," Bentley said.
The agency warned businesses about the anticipated crush of applications last month.
Each year 65,000 visas are awarded to companies looking to hire high-skilled workers from around the world; 20,000 more visas are available specifically for foreign workers who have earned a master's or another advanced degree from a U.S. university.
Even if applications don't exceed the availability this week, immigration attorneys and other experts predicted they would be snatched up faster than in recent years. It took 10 weeks to hit the cap in the 2013 budget year that began last October and more than 33 weeks to dole out all the available visas the year before.
A growing economy is contributing to the rush this year, but the scramble is also a sign that demand for the visas exceeds the available supply. Proposals to increase the number of available visas have been supported by lawmakers and political candidates in recent years and are now considered a key part of immigration reform plans in Congress.
"Our current immigration laws do not prioritize immigrants based on the skills and education they bring to our country," said Rep. Bob Goodlatte, R-Va., chairman of the House Judiciary Committee. He said the U.S. selects only about 12 percent of legal immigrants on the basis of their special skills.
Improving the system for foreign workers has been a sticking point among lawmakers. In November, the Republican-controlled House passed a bill to make green cards available to foreign students graduating from U.S. universities with advanced degrees in science and math while eliminating the government's Diversity Visa Lottery Program. That program randomly awards 55,000 visas to immigrants from countries with historically low rates of immigration to the United States. Democrats have largely supported the diversity lottery, and the bill was blocked in the Senate.
Holleyman of the Software Alliance said immigration reform and improvements to education in science, technology, engineering and math for U.S. students are the best ways to make sure U.S. employers have enough skilled workers.
The rush for these visas will be another signal to Congress that an overhaul of the program is needed as part of a broader immigration plan, said Neil Ruiz, an associate fellow at the Brookings Institution's Metropolitan Policy Program.
"Once Congress comes back next week," Ruiz said, "they will say, 'Ah-ha, we need this and we need to do this now.'"
___
Follow Alicia A. Caldwell on Twitter at www.twitter.com/acaldwellap
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This Raspberry Pi-Powered Backup Camera Sounds the Alarm Before You Hit Something
You can see a brief demo of the system in the video above, and you'll definitely need to be a little familiar with electronics to make this one yourself, but that shouldn't be a problem for you, right? The best part of the whole thing is that you don't need specifically crazy parts to make this work. Jeremy Blythe, the man behind the build, used a Raspberry Pi, a 2.2" LCD from Adafruit, a Sharp distance sensor, and a Microsoft Lifecam camera (which connects to a USB port on the board) to put the whole thing together. He documents the build and includes the code you'll need to get the whole thing up and running at the link below.
Raspberry Pi Parking Camera with Distance Sensor | Jeremy's Blog via Hack a Day
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Tuesday, April 2, 2013
Too early for 2016? Not for Hillary Clinton's fans
FILE - In this Dec. 7, 2009 file photo, then-Secretary of State Hillary Rodham Clinton stands with Vice President Joe Biden in the Oval Office of the White House in Washington. As Hillary Rodham Clinton?s supporters urge her to run for president in 2016, the former first lady/senator/secretary of state makes her first public appearance since leaving government. Many Democrats see Clinton as the party?s early front-runner, and some want her to signal her interest soon to lock down donors and supporters. Fueling the 2016 chatter: Vice President Joe Biden, another possible candidate, will speak at the same awards ceremony. (AP Photo/Susan Walsh, File)
FILE - In this Dec. 7, 2009 file photo, then-Secretary of State Hillary Rodham Clinton stands with Vice President Joe Biden in the Oval Office of the White House in Washington. As Hillary Rodham Clinton?s supporters urge her to run for president in 2016, the former first lady/senator/secretary of state makes her first public appearance since leaving government. Many Democrats see Clinton as the party?s early front-runner, and some want her to signal her interest soon to lock down donors and supporters. Fueling the 2016 chatter: Vice President Joe Biden, another possible candidate, will speak at the same awards ceremony. (AP Photo/Susan Walsh, File)
WASHINGTON (AP) ? Hillary Rodham Clinton stayed on safe political ground Tuesday, advocating women's rights globally in a 12-minute speech, but that was enough to excite fans imploring the former first lady, senator and secretary of state to run again for president three years from now.
Clinton, perhaps as popular as ever in her 22 years in national politics, said she has "unwavering faith in the untapped potential of women and girls." She spoke at the Vital Voices Global Leadership Awards, at Washington's Kennedy Center. The event, highlighting efforts such as expanding education for girls and fighting domestic violence worldwide, marked her first public speech since ending her much-praised stint as secretary of state.
As members of the group Ready for Hillary cheered outside, the 2016 political buzz was inevitable. Vice President Joe Biden ? another potential Democratic candidate ? spoke later at the same event.
If Clinton has any jealousy, she didn't show it. She praised Biden effusively, especially for his role in Congress' recent renewal of the Violence Against Women Act.
Biden returned the compliment a half-hour later, after Clinton had left the stage, telling the mostly female audience of more than 2,000 that "there's no woman like Hillary Clinton."
Biden said Clinton's declaration in China nearly two decades ago ? "Women's rights are human rights," she said at the time ? "still echoes forcefully around the world." Women everywhere, he said, "are entitled to every single opportunity that any man is."
Clinton, 65, has said she has no plans for a second presidential bid, but she hasn't ruled it out. Democrats argue among themselves whether she has the desire and energy to go through the grueling campaign process she knows so well. But many see her as a prohibitive favorite whose head start would be so big that other potential candidates might starve for funds and attention.
A Washington Post-ABC News poll in January found that 67 percent of Americans held a favorable view of Clinton. That's her highest rating since the poll began measuring her popularity in the 1990s. It spans her eight years in the Senate.
"It's hard to overstate the breadth and depth of enthusiasm for a Hillary run," said Doug Hattaway, a former Clinton campaign aide and now a Washington-based consultant. She built a national base of supporters in 2008, when she lost a hard-fought nomination fight to Barack Obama, and she's widely respected after her turn heading the State Department, Hattaway said.
"A lot of donors, volunteers and potential campaign workers will wait to hear what she decides before committing to other candidates," he said, although "anyone with their eye on 2016 is already working on it."
Mo Elleithee, a top spokesman for Clinton's 2008 campaign, said it's much too early to press her for an answer.
"My advice to everyone is to chill out," Elleithee said. "There's no need for all this breathless anticipation at this point," he said, and political activists should focus on next year's mid-term elections.
Noting that Clinton said she has no intention of running, he said, "I think that's where her head is." But he said he shares "the enthusiasm" for a Clinton candidacy.
There may be no one in America with a clearer view of what it takes to run for president.
Clinton was a highly visible adviser and defender of her husband, Bill, then the Arkansas governor, when he was elected president in 1992 in 1996. Her eight years as first lady included the excruciating Monica Lewinsky scandal and her husband's impeachment.
On the same day her husband's successor was elected, Clinton handily won a Senate seat from New York. She breezed to re-election in 2006 and was the early favorite for the 2008 presidential nomination.
But Obama used his early opposition to the Iraq war, plus a keen understanding of how to win small states' delegates, to outmaneuver the Clinton team. Obama promptly tapped his former rival to be secretary of state, assuring Clinton another prime post at the center of national policy and politics.
Some Democrats want the party to look to younger candidates, noting that Clinton will turn 69 shortly before Election Day 2016, and Biden will turn 74 soon after. Those drawing notice include New York Gov. Andrew Cuomo, 55, and Maryland Gov. Martin O'Malley, 50.
As runner-up in the 2008 Democratic primary, Clinton arguably is the party's heir apparent. Republicans, not Democrats, typically nominate the next-in-line contender.
With the early GOP presidential picture wildly scrambled, it's possible that Republicans will tap a newer, younger nominee while Democrats consider one of the nation's best-known figures, and certainly the most high-profile female politician.
Clinton is scheduled to speak Friday at the Women in the World Summit in New York.
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DARPA working on low-cost robot hands, aims to make yours even more idle (video)
In a bid to crush those typically high robot-making costs, DARPA and its business partners (including iRobot) reckon they can now build high-end robot hands for under $3,000, down from what was once a $10,000 premium. According to The New York Times, the government, specifically the Pentagon, is looking to craft robot mitts that are able to detect improvised explosive devices by touch alone -- something that DARPA's worked on before. To demonstrate the progress it's made so far, the department's released a clip of one of its robots stripping a car tire -- you'll find it after the break. Now it just needs to figure out how to get it back on to the wheel.
Via: The Verge
Source: The New York Times
Source: http://feeds.engadget.com/~r/weblogsinc/engadget/~3/8M8tWTPjRRc/
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