Packing hundreds of sensors into a single optical fiber for use in harsh environments

By fusing together the concepts of active fiber sensors and high-temperature fiber sensors, a team of researchers at the University of Pittsburgh has created an all-optical high-temperature sensor for gas flow measurements that operates at record-setting temperatures above 800 degrees Celsius.

This technology is expected to find industrial sensing applications in harsh environments ranging from deep geothermal drill cores to the interiors of nuclear reactors to the cold vacuum of space missions, and it may eventually be extended to many others.

The team describes their all-optical approach in a paper published today in The Optical Society's (OSA) journal Optics Letters. They successfully demonstrated simultaneous flow/temperature sensors at 850 C, which is a 200 C improvement on an earlier notable demonstration of MEMS-based sensors by researchers at Oak Ridge National Laboratory.

The basic concept of the new approach involves integrating optical heating elements, optical sensors, an energy delivery cable and a signal cable within a single optical fiber. Optical power delivered by the fiber is used to supply energy to the heating element, while the optical sensor within the same fiber measures the heat transfer from the heating element and transmits it back.

"We call it a 'smart optical fiber sensor powered by in-fiber light'," said Kevin P. Chen, an associate professor and the Paul E. Lego Faculty Fellow in the University of Pittsburg's Department of Electrical and Computer Engineering.

The team's work expands the use of fiber-optic sensors well beyond traditional applications of temperature and strain measurements. "Tapping into the energy carried by the optical fiber enables fiber sensors capable of performing much more sophisticated and multifunctional types of measurements that previously were only achievable using electronic sensors," Chen said.

In microgravity situations, for example, it's difficult to measure the level of liquid hydrogen fuel in tanks because it doesn't settle at the bottom of the tank. It's a challenge that requires the use of many electronic sensors -- a problem Chen initially noticed years ago while visiting NASA, which was the original inspiration to develop a more streamlined and efficient approach.

"For this type of microgravity situation, each sensor requires wires, a.k.a. 'leads,' to deliver a sensing signal, along with a shared ground wire," explained Chen. "So it means that many leads -- often more than 40 -- are necessary to get measurements from the numerous sensors. I couldn't help thinking there must be a better way to do it."

It turned out, there is. The team looked to optical-fiber sensors, which are one of the best sensor technologies for use in harsh environments thanks to their extraordinary multiplexing capabilities and immunity to electromagnetic interference. And they were able to pack many of these sensors into a single fiber to reduce or eliminate the wiring problems associated with having numerous leads involved.

Source: Sciencedaily.com

EPA, eco groups at odds in climate change case

Who has the right to make the rules: the government agency or a federal court?

WASHINGTON — The Obama administration and environmental interests generally agree that global warming is a threat that must be dealt with.

But they're on opposite sides of a Supreme Court case over the ability of states and groups such as the Audubon Society that want to sue large electric utilities and force power plants in 20 states to cut their emissions.

The administration is siding with American Electric Power Co. and three other companies in urging the high court to throw out the lawsuit on grounds the Environmental Protection Agency, not a federal court, is the proper authority to make rules about climate change. The justices will hear arguments in the case Tuesday.

The court is taking up a climate change case for the second time in four years. In 2007, the court declared that carbon dioxide and other greenhouse gases are air pollutants under the Clean Air Act. By a 5-4 vote, the justices said the EPA has the authority to regulate those emissions from new cars and trucks under that landmark law. The same reasoning applies to power plants.

The administration says one reason to end the current suit is that the EPA is considering rules that would reduce carbon dioxide emissions from power plants. But the administration also acknowledges that it is not certain that limits will be imposed.

At the same time, Republicans in Congress are leading an effort to strip the EPA of its power to regulate greenhouse gases.

'The ultimate backstop' 

The uncertainty about legislation and regulation is the best reason for allowing the case to proceed, said David Doniger, a lawyer for the Natural Resources Defense Council, which represents Audubon and other private groups dedicated to land conservation.

"This case was always the ultimate backstop," Doniger said, even as he noted that the council would prefer legislation or EPA regulation to court decisions. The suit would end if the EPA does set emission standards for greenhouse gases, he said.

The legal claims advanced by six states, New York City and the land trusts would be pressed only "if all else failed," he said.

When the suit was filed in 2004, it looked like the only way to force action on global warming. The Bush administration and the Republicans in charge of Congress doubted the EPA's authority to regulate greenhouse gases.

Federal courts long have been active in disputes over pollution. But those cases typically have involved a power plant or sewage treatment plant that was causing some identifiable harm to people, and property downwind or downstream of the polluting plant.

Global warming, by its very name, suggests a more complex problem. The power companies argue that any solution must be comprehensive. No court-ordered change alone would have any effect on climate change, the companies say.

"This is an issue that is of worldwide nature and causation. It's the result of hundreds of years of emissions all over the world," said Ed Comer, vice president and general counsel of the Edison Electric Institute, an industry trade group.

Read full story at http://on.msnbc.com/eOg487

Russia bans polar bear hunt this year

MOSCOW — Russia has banned the hunting of polar bears this year, thanks to a group with close ties to Prime Minister Vladimir Putin, a longtime defender of large endangered animals.

A Russian-U.S. commission last year agreed to restrict polar bear hunting to 29 animals per year for each country. But The Polar Bear program, established under Putin's patronage, said this week that Russia had waived its quota for bear hunting.


Although the polar bear is an endangered animal, officials in Russia and the U.S. have said hunting is vital for the indigenous people in Alaska and in far-eastern Russia across the Bering Strait.

The Polar Bear program, which said U.S. officials had long been reluctant to introduce the cap on hunting, said around 100 polar bears a year have been killed in Alaska in recent years.

"Measures taken by Russia will ensure that the United States will be killing at least 70 polar bears fewer than before, which, according to Russian specialists, will help to sustain and boost the population of this beautiful Arctic animal," the group said in a statement posted on Putin's official website.

Putin last year helped scientists put a tracking collar on a sedated male polar bear. Before leaving the bear, he patted the animal affectionately, shook his paw and said "take care."

He also joined scientists last year in studying the gray whale off Russia's Pacific Coast, firing darts from a crossbow to collect skin samples from a whale swimming near their small boat.

Putin also has championed the cause of endangered big cats. In 2008, he was given a 2-month-old female Siberian tiger cub for his birthday, which he later gave to a zoo in southern Russia.

Source: msnbc.com