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Updates from Georgia Tech

Researchers Boost Efficiency and Stability of Optical Rectennas
By John Toon – The research team that announced the first optical rectenna in 2015 is now reporting a two-fold efficiency improvement in the devices — and a switch to air-stable diode materials. The improvements could allow the rectennas – which convert electromagnetic fields at optical frequencies directly to electrical current – to operate low-power devices such as temperature sensors.

Optical rectennas operate by coupling the light’s electromagnetic field to an antenna, in this case an array of multiwall carbon nanotubes whose ends have been opened. The electromagnetic field creates an oscillation in the antenna, producing an alternating flow of electrons. When the electron flow reaches a peak at one end of the antenna, the diode closes, trapping the electrons, then re-opens to capture the next oscillation, creating a current flow.

The switching must occur at terahertz frequencies to match the light. The junction between the antenna and diode must provide minimal resistance to electrons flowing through it while open, yet prevent leakage while closed.

“The name of the game is maximizing the number of electrons that get excited in the carbon nanotube, and then having a switch that is fast enough to capture them at their peak,” Baratunde Cola, explained. “The faster you switch, the more electrons you can catch on one side of the oscillation.” more>

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Updates from Georgia Tech

Imaging Technique Unlocks the Secrets of 17th Century Artists
By John Toon – The secrets of 17th century artists can now be revealed, thanks to 21st century signal processing. Using modern high-speed scanners and the advanced signal processing techniques, researchers at the Georgia Institute of Technology are peering through layers of pigment to see how painters prepared their canvasses, applied undercoats, and built up layer upon layer of paint to produce their masterpieces.

The images they produce using the terahertz scanners and the processing technique – which was mainly developed for petroleum exploration – provide an unprecedented look at how artists did their work three centuries ago. The level of detail produced by this terahertz reflectometry technique could help art conservators spot previous restorations of paintings, highlight potential damage – and assist in authenticating the old works.

Beyond old art, the nondestructive technique also has potential applications for detecting skin cancer, ensuring proper adhesion of turbine blade coatings and measuring the thickness of automotive paints.

Without the signal processing, researchers might only be able to identify layers 100 to 150 microns thick. But using the advanced processing, they can distinguish layers just 20 microns thick. Paintings done before the 18th century have been challenging to study because their paint layers tend to be thin, Citrin said. Individual pigments cannot be resolved by the technique, though the researchers hope to be able to obtain that information in the future. more>

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Updates from Georgia Tech

Daydreaming is Good. It Means You’re Smart
By Jason Maderer – A new study from the Georgia Institute of Technology suggests that daydreaming during meetings isn’t necessarily a bad thing. It might be a sign that you’re really smart and creative.

“People with efficient brains may have too much brain capacity to stop their minds from wandering,” said Eric Schumacher, the Georgia Tech associate psychology professor who co-authored the study.

Schumacher says higher efficiency means more capacity to think, and the brain may mind wander when performing easy tasks.

How can you tell if your brain is efficient? One clue is that you can zone in and out of conversations or tasks when appropriate, then naturally tune back in without missing important points or steps.

“Our findings remind me of the absent-minded professor — someone who’s brilliant, but off in his or her own world, sometimes oblivious to their own surroundings,” said Schumacher. “Or school children who are too intellectually advanced for their classes. While it may take five minutes for their friends to learn something new, they figure it out in a minute, then check out and start daydreaming.” more>

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Updates from Georgia Tech

Driving Cassini: Doctoral Student Controls Spacecraft in Mission’s Final Days

By Jason Maderer – When the Cassini spacecraft plunges into Saturn on September 15 to end a nearly two-decade mission, Georgia Tech student Michael Staab will have a front row seat. It’s almost literally the driver’s seat.

Staab is working at NASA’s Jet Propulsion Laboratory (JPL) in California while pursuing his aerospace engineering doctoral degree in the distance learning program. He’s a Cassini Spacecraft Flight Controller, which means he’s one of only three people authorized to tell the machine what to do and where to go as it orbits Saturn.

The job is almost finished. Just before 8 a.m. (Atlanta time) on Friday, Staab will hear Cassini’s signal for the final time before it dives into the planet’s atmosphere, becoming a part of Saturn.

Prior to attending Georgia Tech, I was a flight test engineering intern at NASA’s Armstrong Flight Research Center at Edwards Air Force Base in California and, later, a test requirements and analysis engineer for Boeing in St. Louis. I had a lot of control room and operations experience, which is exactly what JPL was looking for.

The duty of a flight controller at JPL is fairly straight-forward; we possess absolute command and control authority of the spacecraft when tracking it through the Deep-Space Network. more> https://goo.gl/aAU76G

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Updates from Georgia Tech

You and Some ‘Cavemen’ Get a Genetic Health Check
By Ben Brumfield – Heart problems were much more common in the genes of our ancient ancestors than in ours today, according to a new study by geneticists at the Georgia Institute of Technology, who computationally compared genetic disease factors in modern humans with those of people through the millennia.

Overall, the news from the study is good. Evolution appears, through the ages, to have weeded out genetic influences that promote disease, while promulgating influences that protect from disease.

But for us modern folks, there’s also a hint of bad news. That generally healthy trend might have reversed in the last 500 to 1,000 years, meaning that, with the exception of cardiovascular ailments, disease risks found in our genes may be on the rise. For mental health, our genetic underpinnings look especially worse than those of our ancient forebears. more> https://goo.gl/txQhqU

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Updates from Georgia Tech

Smart Cities
By T.J. Becker – Cities have been around for thousands of years, so urbanization is hardly a new phenomenon — but it’s happening now at an unprecedented pace.

In 1950 about 30 percent of the world’s population lived in cities, a number that shot up to nearly 55 percent by 2016 and is expected to hit 60 percent by 2030, according to United Nations statistics. This dramatic growth brings challenges on a variety of fronts, transforming “smart cities” from a catchy phrase into a critical endeavor.

“Smart cities is a highly complex area, encompassing everything from resiliency and environmental sustainability to wellness and quality of life,” said Elizabeth Mynatt, executive director of Georgia Tech’s Institute for People and Technology (IPaT) and distinguished professor in the College of Computing, who is co-chairing the new council. “Although Georgia Tech has been working in this area for some time, we’re organizing research so we can be more holistic and have combined impact.”

“Instead of discrete projects, we’re moving into a programmatic approach,” agreed Jennifer Clark, associate professor of public policy and director of Georgia Tech’s Center for Urban Innovation. “Smart cities research touches on everything from computing and engineering to the social sciences. It’s a different way of thinking about technology — not just in the private sector but also the public sector — so we make cities more efficient and economically competitive places.” more> https://goo.gl/DtKr9K

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Updates from Georgia Tech

Researchers Create 3-D Printed Tensegrity Objects Capable of Dramatic Shape Change
By Ke Liu, Jiangtao Wu, Glaucio H. Paulino, and H. Jerry Qi – A team of researchers from the Georgia Institute of Technology has developed a way to use 3-D printers to create objects capable of expanding dramatically that could someday be used in applications ranging from space missions to biomedical devices.

The new objects use tensegrity, a structural system of floating rods in compression and cables in continuous tension. The researchers fabricated the struts from shape memory polymers that unfold when heated.

“Tensegrity structures are extremely lightweight while also being very strong,” said Glaucio Paulino, a professor in Georgia Tech’s School of Civil and Environmental Engineering. “That’s the reason there’s a heavy amount of interest right now in researching the use of tensegrity structures for outer space exploration. The goal is to find a way to deploy a large object that initially takes up little space.” more> https://goo.gl/bVJHjf

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Updates from Georgia Tech

Decades of Data on World’s Oceans Reveal a Troubling Oxygen Decline
By Takamitsu Ito, Shoshiro Minobe, Matthew C. Long and Curtis Deutsch – A new analysis of decades of data on oceans across the globe has revealed that the amount of dissolved oxygen contained in the water – an important measure of ocean health – has been declining for more than 20 years.

The majority of the oxygen in the ocean is absorbed from the atmosphere at the surface or created by photosynthesizing phytoplankton. Ocean currents then mix that more highly oxygenated water with subsurface water. But rising ocean water temperatures near the surface have made it more buoyant and harder for the warmer surface waters to mix downward with the cooler subsurface waters. Melting polar ice has added more freshwater to the ocean surface – another factor that hampers the natural mixing and leads to increased ocean more> stratification.

Falling oxygen levels in water have the potential to impact the habitat of marine organisms worldwide and in recent years led to more frequent “hypoxic events” that killed or displaced populations of fish, crabs and many other organisms. more> https://goo.gl/3F17TB

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Updates from Georgia Tech

Surprising twist in confined liquid crystals: A simple route to developing new sensors
By Karthik Nayani, Jinxin Fu, Rui Chang, Jung Ok Park, and Mohan Srinivasarao – To answer some fundamental questions pertaining to the material’s phase behavior, the researchers used the microscopes to observe the molecules’ textures when they were confined to droplets known as tactoids.

“Surprisingly, we found a configuration that hasn’t been seen before in the 70 years that people have been studying liquid crystals,” said Mohan Srinivasarao, a professor in the Georgia Tech School of Materials Science and Engineering. “Historically, liquid crystals in tactoids conform to what is known as a bipolar and a bipolar configuration with a twist. At lower concentrations, we found that these liquid crystals arrange in a concentric fashion, but one that appears to be free of a singular defect.”

The researchers then used a simple model of the aggregation behavior of these molecules to explain these surprising results. Further, spectroscopic experiments using polarized Raman microscopy were performed to confirm their findings.

These new findings add to the growing understanding of how chromonic liquid crystals could be used in sensing applications, Srinivasarao said. more> https://goo.gl/YVq0TE

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Updates from Georgia Tech

New Projects Create a Foundation for Next-Gen Flexible Electronics
By Josh Brown – Four projects set to move forward at the Georgia Institute of Technology aim to lay the groundwork for manufacturing next-generation flexible electronics, which have the potential to make an impact on industries ranging from health care to defense.

Researchers at Georgia Tech are partnering with Boeing, Hewlett Packard Enterprises, General Electric, and DuPont as well other research institutions such as Binghamton University and Stanford University on the projects.

Flexible electronics are circuits and systems that can be bent, folded, stretched or conformed without losing their functionality. The systems are often created using machines that can print components such as logic, memory, sensors, batteries, antennas, and various passives using conductive ink on flexible surfaces. Combined with low-cost manufacturing processes, flexible hybrid electronics unlock new product possibilities for a wide range of electronics used in the health care, consumer products, automotive, aerospace, energy and defense sectors.

“Flexible electronics will make possible new products that will help us address problems associated with food supply, clean water, clean energy, health, infrastructure, and safety and security,” said Suresh Sitaraman, a professor in the George W. Woodruff School of Mechanical Engineering, who is leading Georgia Tech’s flexible electronics activities. more> https://goo.gl/qjx3UT

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