Research Horizons Issue 1 2016: Harvesting a Bountiful Energy Future by Georgia Institute of Technology

ISSUE 1 2016

Shape Shift BY LAURA DIAMOND

POWER GENERATION

Harvesting a Bountiful Energy Future A dozen emerging energy technologies provide power from sources you might never expect. Page 24

Road to Autonomy BY RICK ROBINSON

Cool Chips BY JOHN TOON

Growing Success BY PÃ&#x2030;RALTE C. PAUL

VERY QUIET ROOM The Georgia Tech Research Institute (GTRI) operates an indoor compact range used for radar cross section measurements and antenna testing. The facility is shielded against electromagnetic interference and used for both internal research and collaborations with industry. The range is 18 feet high, 24 feet wide, and 60 feet long. It can test at frequencies ranging from two gigahertz to 100 gigahertz, and that range can be extended down to 200 megahertz to accommodate UHF antenna testing. Shown under test is a Skywalker X8 airframe that is being used as a test bed for swarming UAV research. The aircraft is undergoing antenna pattern characterization as part of an investigation into inter-aircraft communications. Photo by Rob Felt.

EXHIBITA

GRAVITATIONAL WAVES Georgia Tech is a partner in the scientific collaboration for the Laser Interferometer Gravitational-wave Observatory (LIGO) and operates a mock-up LIGO control room on campus. In February, the LIGO Scientific Collaboration announced that it had confirmed the detection of gravitational waves at both LIGO detectors, located in Livingston, Louisiana, and Hanford, Washington. The LIGO observatories are funded by the National Science Foundation, and were conceived, built, and are operated by Caltech and MIT. Photo by Rob Felt R E S E A R C H H O R I ZO N S 3

EXHIBITA

TEST RANGE The Georgia Tech Research Institute (GTRI) operates a far-field antenna test range at its facility in Cobb County, Georgia. The range consists of two multistory signal towers — source and receive — located 1,300 feet apart. The facility features a heavyduty, three-axis positioner capable of handling antennas up to 30 feet in diameter and weighing up to 30,000 pounds. The range’s massive towers ensure extreme mechanical precision and stability. Photos by Rob Felt.

R E S E A R C H H O R I ZO N S 5

ISSUE 1 2016

CONTENTS

D E PA R T M E N T S 1

Exhibit A Unseen facilities help power Georgia Tech research.

Cross Talk Autonomy and energy research help meet future needs.

56 Glossary Explanations for terminology used in this issue.

FRONT OFFICE 11 Profile Melanie Quiver focuses on genetic risks of alcoholism.

24 Power the Future 34 Rolling Robots 42 Cooler Runnings 50 Manufacturing Success

Georgia Tech researchers use emerging technologies to generate energy from sources both large and small. Research helps anticipate and avoid roadblocks on the journey toward an autonomous vehicle revolution. Ever-more-powerful mobile devices, computers, and data centers require new approaches to thermal control. The Georgia MEP helps companies statewide compete in world markets through growth and process improvement.

STAFF Editor John Toon Art Director Erica Endicott Writers T.J. Becker, Laura Diamond, Jason Maderer, Rick Robinson, John Toon, Lance Wallace Photographers Rob Felt, Fitrah Hamid Copy Editor Margaret Tate COVER Photo illustration by Rob Felt and Melanie Goux. Back cover: Georgia Techâ&#x20AC;&#x2122;s campus electric substation. Photo by Fitrah Hamid. ADDRESS CORRECTIONS Please send address corrections to John Toon (jtoon@ gatech.edu) or 404-894-6986. POSTMASTER Please send address changes to: Research News & Publications Georgia Institute of Technology 177 North Avenue NW Atlanta, Georgia 30332-0181â&#x20AC;&#x201E;USA REPRINTS Articles from this magazine may be reprinted with credit to Georgia Tech Research Horizons.

16 Visualization Understanding bacteria cells exposes vulnerabilities.

18 Expertise Stealth sculpture pushes concrete to the limit.

Georgia Tech Associate Professor Baratunde Cola measures the power produced by converting green laser illumination to electricity using a carbon nanotube optical rectenna. F I L E , C O L A : R O B F E LT; E X P E R T I S E : F O R M AT I O N S T U D I O

N16C10206

14 File Microelectronics goes to nanotechnology in 30 years.

Research Horizons magazine is published to communicate the results of research conducted at the Georgia Institute of Technology.

CROSS TALK

School of Mechanical Engineering Assistant Professor Shannon Yee (in the dark jacket) leads a “super” research team dedicated to several of Georgia Tech’s groundbreaking energy projects, highlighted in article on page 24.

POWERING, COOLING AND MOVING GEORGIA TECH DEVELOPS NEW ENERGY, THERMAL, AND AUTONOMOUS VEHICLE TECHNOLOGIES

Steve Cross is Georgia Tech’s executive vice president for research.

FITRAH HAMID

Georgia Tech is developing the next generation of energy technologies that could help power everything from the tiniest of wireless sensors to ultra-efficient homes and businesses. Harvesting energy from mechanical motion and converting heat from the environment are among the strategies, but researchers are also collecting energy from nuclear waste and gathering electricity from radio and television broadcasts. Other research projects are developing smaller heat pumps and better supercapacitors — and examining supercritical carbon dioxide to replace steam in power plants. Putting electricity into computer devices generates heat that must be removed. Georgia Tech researchers are working on new approaches for that, from developing more thermally efficient integrated circuits and water cooled chips to optimizing the design of data centers. Their work could result in more powerful and efficient mobile devices and lower energy costs for the data centers that make cloud computing possible. Also in this issue, you will learn about the many challenges that are slowing the introduction of autonomous vehicles. Operating a driverless car on a smooth highway is one thing; dealing with unpredictable terrain, vehicles that still have drivers, and potential system uncertainty is quite another thing. Georgia Tech researchers are addressing the autonomy issues that will have

to be resolved before we’ll be able to sit back and watch a movie while our autonomous car drives us to work. Finally, this issue of Research Horizons describes the work of the Georgia Manufacturing Extension Partnership, a federally supported program operated at Georgia Tech to assist the state’s manufacturers. The program, which serves Georgia through a statewide network of regional offices, helps companies boost efficiency, improve quality, and serve their customers better. Georgia Tech powers an impressive innovation ecosystem that facilitates transformative opportunities, strengthens collaborative partnerships, and maximizes the economic and societal impact of the Institute’s research. Our goal is to conduct leading-edge research and then transition the results of that research into use. As you read this issue of Research Horizons, you’ll see how we’re leveraging these collaborative partnerships to create game- changing solutions to society’s most challenging problems. We truly are creating the next generation of autonomous vehicles, energy technologies, and thermal control for electronic devices. As always, I welcome your feedback. Enjoy the magazine! Steve Cross Executive Vice President for Research April 2016 R E S E A R C H H O R I ZO N S 7

Juvenile Lake Malawi cichlids in the laboratory of Todd Streelman at Georgia Tech.

Research Technician Teresa Fowler examining jaw structures in the fish.

When a Lake Malawi cichlid loses a tooth, a new one drops neatly into place as a replacement. Why can’t humans similarly regrow lost teeth? Working with hundreds of these colorful fish, researchers are beginning to understand how the animals maintain their teeth throughout their adult lives. By studying how structures in embryonic fish differentiate into either teeth or taste buds, the researchers hope to one day be able to turn on the tooth regeneration mechanism in humans — who, like other mammals, get only two sets of teeth. The work, which also involved a study of dental differentiation in mice, shows that the structures responsible for growing new teeth may remain active for longer than previously thought, suggesting that the process might one day be activated in human adults. “We have uncovered developmental plasticity between teeth and taste buds, and we are trying to

understand the pathways that mediate the fate of cells toward either dental or sensory development,” said Todd Streelman, a professor in Georgia Tech’s School of Biology. “The potential applications to humans makes this interesting to everybody who has dealt with dental issues at one time or another in their lives.” To understand more about the pathways that lead to the growth and development of teeth, Streelman and first author Ryan Bloomquist, a D.MD./Ph.D. student at Georgia Tech and Augusta University, studied how teeth and taste buds grow from the same epithelial tissues in embryonic fish. The research, which also involved scientists from King’s College in London, was reported in the journal Proceedings of the National Academy of Sciences. It was supported by the National Institute of Dental and Craniofacial Research of the U.S. National Institutes of Health. — John Toon

R O B F E LT

LONG IN THE TEETH

FRONTOFFICE

BINARY BLACK HOLE: MATT KINSEY, KARAN JANI, AND MICHAEL CLARK; KOTTKE: CANDLER HOBBS

RIGHT AGAIN, EINSTEIN For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. Georgia Tech scientists collaborated on the discovery, which confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the merger of two black holes to produce a single, more massive spinning black hole. The gravitational waves were detected on September 14, 2015, by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington. The LIGO observatories are funded by the National Science Foundation (NSF) and were conceived and built, and are operated, by Caltech and MIT. The discovery is reported in the journal Physical Review Letters. Twelve Georgia Tech faculty members, postdoctoral researchers, and students are currently involved in the LIGO Scientific Collaboration. The team is led by School of Physics Associate Professor Laura Cadonati, who also chairs the LIGO Data Analysis Council. — Jason Maderer

Visualization of the binary black hole coalescence that is believed to have produced the gravitational waves observed by LIGO.

CAPILLARY CONTROL WITH POLYMER HYDROGEL Georgia Tech Senior Research Engineer Peter Kottke adjusts the optics used in a study of how hydrogel coatings affect capillary action in a narrow glass tube.

Coating the inside of glass microtubes with a polymer hydrogel dramatically alters the way capillary forces draw water into the tiny structures, researchers have found. The discovery could provide a new way to control microfluidic systems, including popular lab-on-a-chip devices. Capillary action draws water and other liquids into confined spaces such as tubes, straws, and wicks, and the flow rate can be predicted using a simple hydrodynamic analysis. But a chance observation by Georgia Tech researchers could change those predictions for conditions in which hydrogel films line the tubes carrying water-based liquids. “In hydrogel-coated tubes, rather than moving according to conventional expectations, water-based liquids slip to a new location in the tube, get stuck, then slip again — and the process repeats over and over again,” explained Andrei Fedorov, a professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering. “Instead of filling the tube at a rate that slows with time, the water propagates at a nearly constant speed into the hydrogel-coated capillary.” When the opening of an ordinary thin glass tube is exposed to a droplet of water, the liquid begins to flow into the tube, pulled by a combination of surface tension and adhesion between the liquid and the walls of the tube. Leading the way is a meniscus, a curved surface of the liquid at the leading edge of the water column. An ordinary borosilicate glass tube fills by capillary action at a gradually decreasing rate with the speed of meniscus propagation slowing as a square root of time. But when the inside of a tube is coated with a very thin layer of a so-called “smart” polymer, everything changes. Water entering a tube coated on the inside with a dry hydrogel film must first wet the film and allow it to swell before it can proceed farther into the tube. The wetting and swelling take place not continuously, but with discrete steps in which the water meniscus first sticks and its motion remains arrested while the polymer layer locally deforms. The meniscus then rapidly slides for a short distance before the process repeats. This “stick-slip” process forces the water to move into the tube in a step-by-step motion. The findings resulted from research sponsored by the Air Force Office of Scientific Research (AFOSR) through the BIONIC center at Georgia Tech, and were reported in the journal Soft Matter. — John Toon

R E S E A R C H H O R I ZO N S 9

FRONTOFFICE

COMING SOON: CLIMATE CHANGE IMPACTS

Military Training Anywhere 10

for addressing the causes will themselves change, the paper’s authors warn. “Our argument is that if you want to do something, you’d better do something now because over time, you are going to lose the ability to have an impact,” said Juan Moreno-Cruz, an assistant professor in Georgia Tech’s School of Economics and one of the paper’s co-authors. “If we delay action on climate change, the likelihood of doing something will be reduced because the damages will be accelerating. The incentives to address it are going to disappear as more damage occurs.” Climate change impacts are often assumed to increase steadily with global temperature increases, but that’s not true for all impacts. The scaling of many impacts with temperature may have a nonlinear sigmoidal pattern, with a dramatic initial impact followed by a leveling off as warming continues, said the paper’s authors at Georgia Tech, the Carnegie Institution for Science at Stanford, and the Pottsdam Institute of Climate Impact Research. — John Toon

The Virtual Electronic Combat Training System (VECTS) provides U.S. aircrews with inflight electronic warfare (EW) training by simulating realistic threats on an aircraft’s built-in EW warning system. Developed at the Georgia Tech Research Institute, VECTS’ advantages include the ability to test equipment functionality and aircrew readiness under many different threat scenarios, along with the convenience and cost savings of not requiring a ground range to perform EW test simulations. A new version called VECTS+ includes full multiship functionality — the ability for two or more aircraft to train together realistically regardless of their physical locations. — Rick Robinson

GOOGLE EARTH

Juan Moreno-Cruz is an assistant professor in Georgia Tech’s School of Economics. He is working with other scientists to understand the economic issues involved in climate change impacts.

For the 70,000 residents of the Marshall Islands, global climate change isn’t a theoretical concern with far-off consequences. The island nation is no more than 6 feet above the Pacific Ocean, and because sea levels are already rising, the nation’s leaders have made plans to move the entire population to higher ground in the Fiji Islands. Some impacts of global climate change will appear much sooner than others with only moderate increases in global temperature. For example, while rising sea level may one day threaten the subway lines of New York City, it will have effects much sooner in other parts of the world. Rising temperatures may one day make parts of the globe uninhabitable, but smaller temperature changes have already begun to decimate Pacific coral reefs. Only immediate and aggressive efforts to mitigate the effects of climate change can head off these accelerating near-term impacts, argues a commentary paper published in the journal Nature Geoscience. As more impacts occur, the incentives

PROFILE

Melanie Quiver, a Ph.D. student in Georgia Tech's School of Biology, studies human population genetics and evolutionary genomics to assess the genetic risk of alcoholism.

HUMAN FACTORS Melanie Quiver, a Ph.D. student in Georgia Tech’s School of Biology, is a member of the Lachance Lab, which studies human population genetics and evolutionary genomics. Quiver’s research focuses on the genetic risk of alcoholism in modern populations.

WHERE ARE YOU FROM? I’m from a small town called Kayenta, on the Navajo reservation in northern Arizona. I am of the Tangle People clan, born for the San Felipe Pueblo Fox clan. My maternal grandfather was of the Deer Springs People clan and my paternal grandfather was of the Bitter Water People clan. WHAT BROUGHT YOU TO GEORGIA TECH? I attended Northern Arizona University for my undergrad, where I also worked at the Center for Microbial Genetics and Genomics. I graduated with a B.S. in biology in 2014. Graduate school was never part of the plan, but my mentor, Jeff Foster, encouraged me to apply to the FOCUS R O B F E LT

program. The three-day event at Georgia Tech is designed to raise awareness of graduate education among underrepresented students. I attended the program in January 2014 and that experience is why I’m here today. The amount of information and support I received was so overwhelming that it didn’t take me long to become confident in my ability to be a successful Ph.D. student here.

WHAT IS THE FOCUS OF YOUR RESEARCH? Broadly, I’m interested in whole-genome sequences and their application in understanding how human population movement has shaped disease risk in terms of genetics. My current goal is to explore the effects of rapid reductions in human population sizes throughout history (genetic bottlenecks) and how this might have shaped genetic differences in the risk of alcoholism. For example, our most recent paper inferred historic population sizes using X-chromosome and autosomal data from 11 global populations. Findings from this work include evidence of a

male-biased migration out of Africa, which could help lead to important insight in the selective constraint of X-linked diseases. This research topic is near and dear to my heart, as I’m from a population that has experienced both genetic bottlenecks and a severe public health burden involving alcohol addiction.

IT SEEMS AS THOUGH YOUR INTEREST AND PASSION IN BIOLOGY IS INTERWOVEN INTO YOUR BACKGROUND. It’s primarily because of where I grew up. The Navajo reservation is prevalent with addiction in various forms, such as alcohol, drugs, and gambling. This has affected the mindset of our youth. We have the lowest (college) enrollment numbers in history, and I think that introduces an opportunity for improvement. It’s my hope that I contribute to that improvement and inspire indigenous youth to go after their passion as well. Graduate school can be challenging, but that doubt disappears the second I remember who I’m doing it for: my community. — Laura Diamond R E S E A R C H H O R I ZO N S 1 1

FRONTOFFICE

Location, Location, Location

Biomedical engineers have demonstrated a proof-of-principle technique that could give women and their oncologists more personalized information to help them choose options for treating breast cancer. Thanks to diagnostic tests, clinicians and patients can already know the type of breast cancer they’re up against, but one big question remains: How likely is it that the cancer will invade other parts of the body? Answering that question could help guide treatment selection: from aggressive and difficult therapies, such as prophylactic mastectomy, to more conservative ones. By studying chemical signals from specific cells that are involved in helping cancer invade other tissues in each woman’s body, researchers have developed a predictive model that could provide an invasiveness index for each patient. “We want women to have more information to make a personal decision beyond the averages calculated for an entire population,” said Manu Platt, an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “We are using our systems biology tools and predictive medicine approaches to look at potential markers we could use to help us understand the risk each woman has. This would provide information for a more educated discussion of treatment options.” Platt’s research team is examining chemical signals produced by the macrophages that can help aggressive tumors invade new tissues. Macrophages normally clean up foreign particles and harmful microorganisms in the body, but aggressive tumors can enlist macrophages in helping them metastasize. Tumor-associated macrophages contribute significantly to tumor invasion, with cysteine cathepsin proteases — enzymes that break down proteins in the body — important contributors. The research, supported by Georgia Research Alliance funds and the Giglio family donation, has been reported in the journal Scientific Reports. Beyond breast cancer, the technique could offer similar decision-making assistance for men with prostate cancer, where treatment also requires making difficult choices about the risk of metastasis. — John Toon

Manu Platt is an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. He studies tissue remodeling in regenerative medicine and micro-environmental cues modulating stem cell signaling networks.

This super-resolution fluorescence microscopy image of HyPer-Tau shows the microtubular structure of a human (HeLa) cancer cell. The image was made using the new super-resolution microscope in the Georgia Tech Institute for Bioengineering & Bioscience (IBB).

C A N C E R : I STO C K P H OTO ; H Y P E R -TAU : E M I L I E WA R R E N

AN 'INVASIVENESS INDEX' FOR BREAST CANCER

By attaching a hydrogen peroxide reporter protein to cellular microtubule structures, researchers have developed the first sensor able to map the location of the key cellular signaling chemical inside living cells with high resolution over time. Until development of the new sensor, hydrogen peroxide sensors could only tag certain components of cells, or show that the cells were globally oxidized. To understand the role of hydrogen peroxide in signaling, researchers needed time-resolved location information. The HyPer-Tau sensor was developed by researchers who have already demonstrated several applications for its ability to spatially resolve the chemical’s presence inside cancer and immune cells that are actively responding to environmental cues. “The chemistry of cells, unlike more traditional chemistry in test tubes, is highly dependent on where a chemical reaction is occurring,” said Christine Payne, an associate professor in Georgia Tech’s School of Chemistry and Biochemistry and one of the paper’s senior authors. “We needed a tool that could discriminate between locations to provide more than a whole readout of oxidation,” said Melissa Kemp, an associate professor in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University. “With very specific spatial information, we will be better informed about how cellular processes or antioxidant therapies are going to operate.” Other researchers had already created variants of the commercially available HyPer reporter protein, which alters its fluorescence properties in the presence of hydrogen peroxide. Here, the researchers added a tubulin-binding protein known as Tau that anchors the protein to microtubule structures that crisscross cells like railroad tracks. Fluorescence microscopy then allows them to observe the real-time change as oxidation occurs. The work was supported by the National Institutes of Health and reported in the journal Scientific Reports. — John Toon

FRONTOFFICE

ANALYTICAL CHEMISTRY OFFERS EARLY WARNING Metabolic Profiles Distinguish Early-Stage Ovarian Cancer

John McDonald is a professor in Georgia Tech’s School of Biology and director of its Integrated Cancer Research Center.

R O B F E LT

Facundo Fernández is a professor in the Georgia Tech School of Chemistry and Biochemistry.

Studying blood serum compounds has led scientists to a set of biomarkers that may enable development of a highly accurate screening test for early-stage ovarian cancer. Using advanced liquid chromatography and mass spectrometry techniques coupled with machine-learning computer algorithms, researchers have identified 16 metabolite compounds that provided unprecedented accuracy in distinguishing 46 women with early-stage ovarian cancer from a control group of 49 women who did not have the disease. While the set of biomarkers is the most accurate reported thus far for early-stage ovarian cancer, more extensive testing is needed to determine if the diagnostic accuracy will be maintained across a larger group of women. “This work provides a proof of concept that using an integrated approach combining analytical chemistry and learning algorithms may be a way to identify optimal diagnostic features,” said John McDonald, a professor in Georgia Tech’s School of Biology and director of its Integrated Cancer Research Center. “We think our results show great promise and we plan to further validate our findings across much larger samples.” Ovarian cancer has been difficult to treat because it typically is not diagnosed until after it has spread to other areas of

the body. Researchers have been seeking a routine screening test that could diagnose the disease while it is confined to the ovaries. Working with cancer treatment centers in the U.S. and Canada, the researchers obtained blood samples from women with stage one and stage two ovarian cancers. They separated out the serum, which contains proteins and metabolites — molecules produced by enzymatic reactions in the body. The serum samples were analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS), two instruments joined together to better separate samples into their individual components. The researchers decided to look only at the metabolites. “People have been looking at proteins for diagnosis of ovarian cancer for a couple of decades, and the results have not been very impressive,” said Facundo Fernández, the professor in Georgia Tech’s School of Chemistry and Biochemistry who led the analytical chemistry part of the research. “We decided to look in a different place for molecules that could potentially provide diagnostic capabilities.” The research was reported in the journal Scientific Reports. — John Toon

Samples are shown ready for testing in an ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) instrument in the laboratory of Facundo Fernández at Georgia Tech. The UPLC-MS technique was used to help identify 16 metabolites associated with early-stage ovarian cancer.

R E S E A R C H H O R I ZO N S 1 3

FILE

MICROELECTRONICS GROWS INTO NANOTECHNOLOGY Researchers work in a clean room space of the Marcus Nanotechnology Building at Georgia Tech. The facility is part of the Institute for Electronics and Nanotechnology.

In 1983, largely on the strength of Georgia Tech, Georgia became a finalist to headquarter the Microelectronics and Computer Technology Corporation (MCC), a pioneering consortium of technology companies. Though Georgia lost out to Austin, Texas, the economic potential of microelectronics was a lesson learned by the state’s economic development community. In the Summer 1986 issue of Research Horizons, plans were announced for a new Microelectronics Research Center, which was envisioned as a $10 million facility funded by the Georgia General Assembly to boost microelectronics research in Georgia. The facility, which became the Joseph M. Pettit Microelectronics Research Center, replaced a smaller facility in the basement of the Van Leer Building, which then hosted the work of some 35 researchers, according to the magazine’s archives. Pettit, Georgia Tech’s president from 1972 until 1986, had promoted microelectronics research and played a key role in the effort to win MCC. Today, the Pettit Building is part of the Institute for Electronics and Nanotechnology (IEN), anchored by the new Marcus Nanotechnology Building. IEN supports the work of some 200 Georgia Tech faculty members, who conduct more than $150 million in total sponsored research. IEN operates approximately 80,000 square feet of clean room, research, fabrication, and characterization laboratories that, in addition to being used by Georgia

Tech faculty and students, are shared by users from more than 70 academic institutions, companies, and government agencies engaged in microelectronics and nanotechnology research. In total, more than 700 users benefit from the IEN fabrication and characterization facilities on an annual basis. IEN is a member of the NSF-funded National Nanotechnology Coordinated Infrastructure (NNCI) and has shared user equipment valued at nearly $250 million. The equipment is used for a broad range of technologies, including nanomaterials and structures; compound and next-generation semiconductors; processing and device fabrication; optoelectronic and photonic devices; micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS); high-speed electronics and wireless systems; interconnect technology; system integration and packaging; and energy harvesting and storage. “Electronics and nanotechnology are essential to all facets of today’s economy, from traditional electronics to new areas in health care and renewable energy,” said Oliver Brand, executive director of IEN. “The original vision for microelectronics has expanded into so many other areas, and just recently to include the manufacturing of therapeutic cells, an innovation that could not have been envisioned with the concept of a shared user facility back in the early 1980s.” — John Toon

R O B F E LT

FRONTOFFICE

Tweeting Etiquette

Georgia Tech Graduate Student Pamela Grothe installs temperature and salinity logging devices on a Christmas Island coral reef to monitor conditions through the 2015-2016 El Niño event.

CO R A L : A LY S S A AT WO O D

DEAD IN THE WATER El Niño conditions in the Pacific Ocean have seriously damaged coral reefs, including those on Christmas Island, which may be the epicenter for what could be a global coral bleaching event. Georgia Tech researchers who visited the island reported that 50 to 90 percent of corals they saw were bleached and as many as 30 percent were dead at some sites. “This El Niño event is driving one of the three largest global-scale bleaching events on record,” said Kim Cobb, a professor in Georgia Tech’s School of Earth and Atmospheric Sciences who has studied long-term El Niño conditions. “Ocean temperatures exceeded the threshold for healthy corals back in the summer.” Bleaching is an outward sign of stress in the corals, which release the symbiotic algae that normally help provide them with energy to sustain their metabolism. The loss of these algae turns the coral colonies white and makes them more vulnerable to disease and death. Bleached corals can recover if water temperatures return to normal. Cobb and other researchers measured water temperatures of 31 degrees Celsius (88 degrees Fahrenheit), well above normal water temperatures of 27 degrees Celsius (81 degrees Fahrenheit). “There’s an astounding amount of warming at this particular site,” Cobb said. “These reefs are under dramatic stress, which is leading to severe coral loss. It will take years for these reefs to recover.” Cobb said the disaster could provide a unique opportunity for studying the long-term ecological impacts of major bleaching events, which could become more frequent as the Earth warms. The El Niño Southern Oscillation (ENSO) is a cycle of warm and cold temperatures that occurs naturally in the central Pacific approximately every two to seven years. By studying fossil coral records from Christmas Island, Cobb and her research team have seen evidence of these cycles dating back at least 7,000 years. However, there is increasing evidence that El Niño events have changed in the past few decades. The research was supported by the National Science Foundation. — John Toon

Kim Cobb is a professor in the School of Earth and Atmospheric Sciences. Her research focuses on bio-geochemistry, the dynamics of weather and climate, oceanography, and paleoclimate.

Despite all the shortened words and slang seen on Twitter, it turns out that people follow many of the same communication etiquette rules on social media as they do in speech. When tweeters use hashtags — a practice that can enable messages to reach more people — they tend to be more formal and drop the use of abbreviations and emoticons. But when they use the @ symbol to address smaller audiences, they’re more likely to use nonstandard words such as “nah” or “cuz.” And when people write to someone from the same city, they are even more likely to use nonstandard language — often lingo that is specific to that geographical area. Jacob Eisenstein, an assistant professor in Georgia Tech’s School of Interactive Computing, led a team that sifted through three years of tweets — a pool that included 114 million geotagged messages from 2.77 million users. He says the study, published in the journal American Speech, helps explain a puzzle about language in social media. “Since social media facilitates conversations between people all over the world, we were curious why we still see such a remarkable degree of geographical differentiation in online language,” Eisenstein said. “Our research shows that the most geographically differentiated language is more likely to be used in messages that will reach only a local audience and, therefore, will be less likely to spread to other locations.” For example, while the emoticon “:)” is used everywhere, the alternative “;o” is significantly more popular in Los Angeles. “People want to show their regional identity or their tech savviness, using Twitter-specific terms, to their close social network ties,” said Umashanthi Pavalanathan, a Georgia Tech graduate research scientist who worked on the study. — Jason Maderer

R E S E A R C H H O R I ZO N S 1 5

VISUALIZATION

MODELING BACTERIA

This detailed model shows how proteins interact with the cell membranes of gram-negative bacteria such as E. coli, N. gonorrhoeae and Salmonella. The goal is to find new ways to attack these microorganisms with antibiotics compounds.

Antibiotic resistance in bacteria is among the most critical public health threats today. As more existing antibiotics lose their ability to battle bacteria, there’s pressure to develop new drugs that can attack the bugs in different ways. Key to that effort is understanding how bacteria operate so new compounds can be developed to attack the microorganisms at their weakest points. Georgia Tech researchers are modeling gram-negative bacteria such as E. coli, N. gonorrhoeae, and Salmonella to find gaps in their cellular defenses — specifically, their outer cell membranes. Having detailed models of these structures can help experimentalists understand what their research is showing and point to new areas of investigation. “One of the helpful things about modeling is that often just having a detailed picture of the system shows you what questions you should be asking,” said J.C. Gumbart, a professor in Georgia Tech’s School of Physics. “It’s really important that we have very accurate models to understand how different bacteria interact with the immune system and with potential drugs in diverse ways.” The bacteria that Gumbart studies are unusual in that they have two outer membranes, one on each side of the cell wall. These membranes are very different from those of other cells, and they have special features that may provide avenues for pharmaceutical attack. But even the best experiments can’t show all of the factors involved in the membranes’ functions, which is why models can be useful. The models, which run on high-performance computers both locally and at national supercomputing centers such as the one at Oak Ridge National Laboratory, combine experimental data with basic principles of biophysics. “We have effectively infinite resolution, and we can present dynamic, atomistic resolution views of the processes going on there,” Gumbart said. Georgia Tech researchers are working with colleagues at the National Institutes of Health, Caltech, Emory University, and other institutions to understand bacteria, including the critical protein BamA, which is responsible for protein insertion into the membrane and could therefore be a target for new antibiotics. — John Toon

CURTIS BALUSEK, HYEA HWANG, JAMES C. GUMBART

FRONTOFFICE

CELLULAR NEW YEAR’S EVE PARTY

H A R V E S T E R S : R O B F E LT; C E L L : E D M O N D C H O W

Energy Harvesters Get Standards More than 60 research groups worldwide are developing variations of the triboelectric nanogenerator (TENG), which converts ambient mechanical energy into electricity for powering wearable electronics, sensor networks, implantable medical devices, and other small systems. To give researchers and developers a way to select the best energy-harvesting nanogenerator for each specific application, the Georgia Tech research group that pioneered the TENG technology has now proposed a set of standards for quantifying device performance. The proposed standards evaluate both the structural and materials performance of the four major types of TENG devices. “Triboelectric nanogenerators are a new energy technology that has shown phenomenal potential,” said Zhong Lin Wang, a Regents Professor in Georgia Tech’s School of Materials Science and Engineering. “Here, we have proposed standards by which the performance of these devices can be quantified and compared. These standards will be useful for academic researchers developing the devices and for future industrial applications of the nanogenerators.” Triboelectric nanogenerators use a combination of the triboelectric effect and electrostatic induction to generate small amounts of electrical power from mechanical motions such as rotation, sliding, or vibration. The triboelectric effect takes advantage of the fact that certain materials become electrically charged after they come into moving contact with a surface made from a different material. The electricity generated by TENG devices could replace or supplement batteries for a broad range of potential applications. Developed over the past several years, the technology has advanced to the point where it can power small electronic devices — potentially enabling widespread sensing and infrastructure systems — as well as wearable consumer devices. The proposed standards were described in the journal Nature Communications. — John Toon

Using large-scale computer modeling, researchers have shown the effects of confinement on macromolecules inside cells — and taken the first steps toward simulating a living cell, a capability that could allow them to pose “what-if” questions impossible to ask in real cells. The work could help scientists better understand signaling between cells and provide insights for designing new classes of therapeutics. For instance, the simulations showed that particles within crowded cells tend to linger near cell walls, while confinement in the viscous liquid inside cells causes particles to move about more slowly than they would in unconfined spaces. The research is a collaboration between Edmond Chow, an associate professor in Georgia Tech’s School of Computational Science and Engineering, and Jeffrey Skolnick, a professor in Georgia Tech’s School of Biology. Their goal is to develop and study models for simulating the motions of molecules inside a cell, and also to develop advanced algorithms and computational techniques for performing large-scale simulations. Skolnick compared the interior of a living cell to a large New Year’s Eve party. “It’s kind of like a crowded party that has big people and little people, snakes — DNA strands — running around, some really large molecules,

and some very small molecules,” he said. “It’s a very heterogeneous and dense environment with as much as 40 percent of the volume occupied.” While the simulations didn’t include the DNA strands or metabolite particles also found in cells, they did include up to a half-million objects. Using physics principles, Skolnick and Chow considered what the particles would do in a cell just a few microns in diameter. “From the results of the computer simulations, we can measure things that we think might be interesting, such as the diffusion rates near the walls and away from the walls,” Chow said. Supported by the National Science Foundation, the results were reported in the journal Proceedings of the National Academy of Sciences. — John Toon

NEGATIVE SCIENCE

Alexander Oettl is an assistant professor in Georgia Tech’s Scheller College of Business.

The number of times academic articles are cited by subsequent publications is among the measures used to assess scholarly standing. But not all citations are positive ones, and a paper published in the journal Proceedings of the National Academy of Sciences found that as many as one in 50 citations in a top immunology journal were critical in nature. Negative citations may point out limitations, inconsistencies, or flaws in previous work. The study found that these negative citations tended to originate from scholars who were close to the authors of the original articles in academic discipline — but at least 150 miles away geographically. The research, by authors at Georgia Tech, the University of Toronto, and the Massachusetts Institute of Technology, may be the first to systematically quantify and examine negative citations. “Given that we rely so heavily on these citation metrics as measures of quality, it’s important to note that the intent of these citations isn’t homogeneous,” said Alexander Oettl, an assistant professor in Georgia Tech’s Scheller College of Business. — John Toon

R E S E A R C H H O R I ZO N S 1 7

EXPERTISE

SHAPE-SHIFTING SCULPTURE

F I N I S H E D S C U L P T U R E : R O B F E LT; C O N S T R U C T I O N : F O R M AT I O N S S T U D I O

TRISTAN AL-HADDAD’S STEALTH PUSHES CONCRETE BEYOND ITS CONVENTIONAL USES Tristan Al-Haddad has transformed a nondescript stretch of concrete jungle in midtown Atlanta with a 33-foot-tall monolithic sculpture. The award-winning piece, Stealth, is a series of interlocking anamorphic projections that create a folded three-dimensional form. From the perspective of a viewer walking around the work — which comprises a rectangle and an elongated hexagon in projection — it both expands and collapses in space. Al-Haddad, an assistant professor in Georgia Tech’s School of Architecture, worked on the piece for more than two and a half years and went through more than 200 iterations of 3-D modeling to get the design just right. While the piece gleams as if it were steel, it is made from concrete. “We were able to produce highly plastic, very thin forms of concrete,” Al-Haddad said. “When you demonstrate that it can be done in an effective and ubiquitous way, you can start to impact the way in which people imagine concrete can be used. That opens new and exciting design opportunities for everyone.” A general rule when using concrete is not to go below an inch of thickness. But Stealth goes down to just one-eighth of an inch in some areas, Al-Haddad said. He worked with Sinclair Construction Group and design engineering firm Uzun & Case to build the sculpture, which was commissioned by Cousins Properties. The sculpture weighs about 70,000 pounds. The structural framework was built in Al-Haddad’s studio and cast-in-place in front of the Promenade Tower. The concrete was poured in 4-foot vertical increments. Eight tons of steel reinforcing bar were cut by hand, bent, and placed in position. Al-Haddad worked with chemists from Thomas Concrete Group for two years to develop the concrete mix. It had to have high strength, while still maintaining the ability to flow into the structure’s sharply angled shapes. Both the coarse and fine aggregate for the concrete were from a blue-black Adairsville granite quarried in North Georgia. The mix included iron oxide and carbon pigments for coloring and synthetic macro fibers for crack control. After casting, the sculpture was diamond-honed to remove any imperfections, and each section was wet polished to give Stealth a sheer, reflective bluish-black finish. The real technical impact of Stealth, Al-Haddad said, could be that it eliminates the fear and risk of what others may try in the future. “This is a demonstration of going beyond the limits of conventional practice,” he said. “When you demonstrate that it can be done, you bring the designers and builders closer together.” — Laura Diamond

(Left) Stealth looms large in the heart of midtown Atlanta. It is located on 15th Street across from the Woodruff Arts Center on Peachtree Street. (Above) The sculpture was cast in place, using a structural framework constructed in the studio.

R E S E A R C H H O R I ZO N S 1 9

FRONTOFFICE

SOL-GEL OFFERS RECORD CAPACITOR ENERGY STORAGE

Building 3-D Nanobridges Researchers have demonstrated a new process for rapidly fabricating complex three-dimensional nanostructures from a variety of materials, including metals. The technique uses nanoelectrospray to provide a continuous supply of liquid precursor, which can include metal ions that are converted to high-purity metal by a focused electron beam. The new process generates structures — such as nanobridges — that would be impossible to make using gas-phase focused electron beam-induced deposition (FEBID) techniques, and allows fabrication at rates up to 5,000 times faster than with the gas-phase technique. And because it uses standard liquid solvents, the new process could take advantage of a broad range of precursor materials. “By allowing us to grow structures much faster with a broad range of precursors, this technique really opens up a whole new direction for making a hierarchy of complex three-dimensional structures with nanoscale resolution at the rate that is demanded for manufacturing scalability,” said Andrei Fedorov, a professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering. In the established FEBID process, an electron beam is used to write structures from molecules adsorbed onto a solid surface that provides support and nucleation sites. The precursors are introduced into the high-vacuum electron microscope chamber in gas phase. High-energy electrons in the beam interact with the substrate to produce the low-energy secondary electrons, which dissociate the adsorbed precursor molecules, resulting in deposition of solid material on the substrate surface. Fedorov and his collaborators have accelerated the original gas-phase process by introducing electrically charged liquid-phase precursors directly into the high vacuum of the electron microscope chamber. The research was supported by the U.S. Department of Energy’s Office of Science and reported in the journal Nano Letters. — John Toon

Joseph Perry is a professor in Georgia Tech’s School of Chemistry and Biochemistry and associate director of the Center for Organic Photonics and Electronics.

Samples of the new hybrid solgel material are shown placed on a clear plastic substrate for testing.

NANOBRIDGES: JEFFREY FISHER; SOL-GEL: JOHN TOON

Illustration shows the 3-D nanoscale deposit fabricated via bridging “arch” connection between two adjacent nanopillars.

Using a hybrid silica sol-gel material and self-assembled monolayers of a common fatty acid, researchers have developed a new capacitor dielectric material that provides an electrical energy storage capacity rivaling certain batteries. If the material can be scaled up from laboratory samples, devices made from it could surpass traditional electrolytic capacitors for applications in electromagnetic propulsion, electric vehicles, and defibrillators. The new material is composed of a silica sol-gel thin film containing polar groups linked to the silicon atoms and a nanoscale self-assembled monolayer of an octylphosphonic acid, which provides insulating properties. The bilayer structure blocks the injection of electrons into the sol-gel material, providing low leakage current, high breakdown strength, and high energy extraction efficiency. “Sol-gels with organic groups are well-known, and fatty acids such as phosphonic acids are well-known,” noted Joseph Perry, a professor in the School of Chemistry and Biochemistry at Georgia Tech. “But to the best of our knowledge, this is the first time these two types of materials have been combined into high-density energy storage devices.” The need for efficient, high-performance materials for electrical energy storage has been growing along with the demand for electrical energy in mobile applications. Dielectric materials can provide fast charge and discharge response, high energy storage, and power conditioning for defense, medical, and commercial applications. But it has been challenging to find a single dielectric material able to meet all of the material needs. Hybrid sol-gel materials had shown potential for efficient dielectric energy storage because of their high orientational polarization under an electric field, so Perry’s research group decided to pursue these materials for the new capacitor applications. The research, supported by the Office of Naval Research and the Air Force Office of Scientific Research, was reported in the journal Advanced Energy Materials. — John Toon

GTRI Research Engineer Paul Robinette adjusts the emergency guide robot.

HELPING ROBOTS FALL GRACEFULLY

G U I D E R O B OT: R O B F E LT; FA L L I N G R O B OT: I S TO C K P H OTO

TRUST A ROBOT IN A FIRE?

In emergencies, people may trust robots too much for their own safety, a new study suggests. In a mock building fire, test subjects followed instructions from an “Emergency Guide Robot” even after the machine had proven itself unreliable — and after some participants were told that the robot had broken down. The research was designed to determine whether or not building occupants would trust a robot designed to help them evacuate a high-rise in case of fire or other emergency. But the researchers were surprised to find that the test subjects followed the robot’s instructions even when the machine’s behavior should not have inspired trust. “People seem to believe that these robotic systems know more about the world than they really do, and that they would never make mistakes or have

any kind of fault,” said Alan Wagner, a senior research engineer in the Georgia Tech Research Institute (GTRI). “In our studies, test subjects followed the robot’s directions even to the point where it might have put them in danger had this been a real emergency.” The research, believed to be the first to study human-robot trust in an emergency situation, was presented at the 2016 ACM/IEEE International Conference on Human-Robot Interaction (HRI 2016). The work was sponsored by the Air Force Office of Scientific Research and also involved Research Engineer Paul Robinette from GTRI, Professor Ayanna Howard from Georgia Tech’s School of Electrical and Computer Engineering, and Georgia Tech Fire Marshal Larry Labbe. — John Toon

Miss Georgia tripped in the final round of the 2015 Miss America Pageant. Jennifer Lawrence stumbled on the way to accepting her Oscar. Rock stars, world leaders, and presidential candidates have all fallen in front of crowds. And robots can too. Now, researchers have identified a way to help robots fall with grace — and without serious damage. This is important now that costly robots have become more common in manufacturing and are sought for health care or domestic tasks. Georgia Tech Ph.D. graduate Sehoon Ha and Professor Karen Liu have developed a new algorithm that tells a robot how to react to a wide variety of falls — from taking a single step to recover from a gentle nudge, to going into a rolling motion to break a high-speed fall. By learning the best sequence of movements to slow their momentum, robots can minimize the damage or injury they might cause to themselves or others while falling. The algorithm has been validated in physics simulation and experimentally tested on a BioloidGP humanoid robot. “A fall can potentially cause damage to the robot and enormous cost to repair,” said Ha, now a postdoctoral associate at Disney Research Pittsburgh. “We believe robots can learn how to fall safely. Our work unified existing research about how to teach robots to fall by giving them a tool to automatically determine the total number of contacts (how many hands shoved it, for example), the order of contacts, and the position and timing of those contacts. All of that impacts the potential of a fall and changes the robot’s response.” The latest finding builds upon Liu’s previous research that studied how cats modify their bodies in the midst of a fall. Liu knew from that work that one of the most important factors in a fall is the angle of the landing. Armed with that information, the two researchers used the robots’ silicon brains to optimize the sequence of motions that take place during a fall. “From previous work, we knew a robot had the computational know-how to achieve a softer landing, but it didn’t have the hardware to move quickly enough like a cat,” said Liu, an associate professor in Georgia Tech’s School of Interactive Computing. “Our new planning algorithm takes into account the hardware constraints and the capabilities of the robot, and suggests a sequence of contacts so the robot gradually can slow itself down.” The research was presented at the IEEE/RSJ International Conference on Intelligent Robots and Systems in Hamburg, Germany. — Jason Maderer R E S E A R C H H O R I ZO N S 2 1

FRONTOFFICE

THE SOUND OF NANOSCALE MATERIALS

A LIGHT TOUCH Having a light touch can make a hefty difference in how well animals and robots move across challenging granular surfaces such as snow, sand, and leaf litter. New research shows how the design of appendages — legs or wheels — affects the ability of robots as well as animals to traverse weak and flowing surfaces. Using an air-fluidized bed trackway filled with poppy seeds or glass spheres, researchers systematically varied the stiffness of the surface to mimic everything from hard-packed sand to powdery snow. By studying how running lizards, geckos, crabs — and a robot — moved through these surfaces, the researchers correlated variables such as appendage design with performance across the range of surfaces. What the scientists learned from this study might help future robots avoid getting stuck in loose soil on some distant planet.

“You need to know systematically how ground properties affect your performance with wheel shape or leg shape, so you can rationally predict how well your robot will be able to move on the surfaces where you have to travel,” said Dan Goldman, a professor in Georgia Tech’s School of Physics. Goldman compares the trackway to wind tunnels used for aerodynamic studies. “By varying the air flow, we can create ground that is very, very weak, so that you sink into it quite easily, like powdery snow, and we can have ground that is very strong, like sand,” he explained. “This gives us the ability to study the mechanism by which animals and robots either succeed or fail.” Reported in the journal Bioinspiration & Biomimetics, the research was supported by National Science Foundation, Army Research Laboratory, and the Burroughs Wellcome Fund. — John Toon

Making solar energy more cost effective The cost of installing photovoltaic systems on buildings stems from three main components: the photovoltaic panels, the racking system that holds the panels, and the labor to affix the panels and racking system to the building or structure. The way the panels are attached to structures is called the “balance of system” for the solar panel. Researchers from the Georgia Tech Research Institute (GTRI) and Georgia Tech’s College of Architecture have been working together to help address balance of system costs, making solar energy a more cost-effective option. “Photovoltaic cells are going to be mainstream,” said Francisco Valdes, a GTRI research engineer. “They will be part of the building. We started with 140 concepts and narrowed it down to five products, two of which are now in production.” The Georgia Tech team developed two solutions for attaching the panels — Quad Pod and Anaconda. The Quad Pod is a canopy solution, while Anaconda is a method of attaching the panels to a flat roof. Both systems have been installed in the Atlanta area, and design improvements are underway as the projects transition into the hands of private companies. — Lance Wallace 22

Understanding where and how phase transitions occur is critical to developing new generations of materials for use in high-performance batteries, sensors, energy-harvesting devices, medical diagnostic equipment, and other applications. But there was no good way to study and simultaneously map these phenomena at the relevant length scales — until now. Researchers from Georgia Tech and Oak Ridge National Laboratory (ORNL)

Schematic represents the atomic force microscope interacting with the material surface in research on investigating phase changes in nanoscale materials.

have developed a new, nondestructive technique for investigating these material changes by examining their acoustic response at the nanoscale. This approach has been used in ferroelectric materials but could also have applications in ferroelastics, solid protonic acids, and materials known as relaxors. “We have developed a new characterization technique that allows us to study changes in the crystalline structure and in materials’ behavior at substantially smaller length scales with a relatively simple approach,” said Nazanin Bassiri-Gharb, an associate professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering. Sponsored by the National Science Foundation and the Department of Energy’s Office of Science, the research was reported in the journal Advanced Functional Materials. — John Toon

C U R I O S I T Y: N A S A / J P L- C A LT E C H / M S S S ; N A N O S C A L E : R A M A VA S U D E VA N , O R N L ; S O L A R : G E O R G I A T E C H

Curiosity on the surface of Mars in 2012. Research being conducted in the School of Physics could help design locomotion structures for future extraplanetary robot explorers.

FRONTOFFICE

NEWSPAPER: LIBRARY OF CONGRESS; U.S. NEWSMAP: COURTESY GTRI

WORD GETS AROUND Populist presidential candidate William Jennings Bryan electrified the 1896 Democratic National Convention with a speech in which he called for a new currency standard based on silver rather than gold. Over the next few years, his “Cross of Gold” idea spread across the country, with thousands of newspaper mentions. But it took 120 years and a collaboration between Georgia Tech data scientists and University of Georgia historians to see exactly how that idea spread. Researchers tracked Cross of Gold using U.S. News Map, a database of more than 10 million newspaper pages that is helping researchers see history with spatial information that hadn’t been available before. “Every historical development has a spatial component to it, and often one that is central to explaining the ‘how’ and the ‘why,’” noted Claudio Saunt, chair of the Department of History at the University of Georgia. “With this new search engine, we now have the ability to see where newspapers were writing about a subject, and how interest in that subject changed over time. It’s a powerful tool for historians, and one that can shed new light on the past.” A free service, the database is available at www.usnewsmap. com. It is based on data from nearly 2,000 U.S. newspapers published between 1836 and 1924 that were scanned by U.S. universities with support from the U.S. Library of Congress. Each word of that text was then indexed for use in the database, explained Trevor Goodyear, a research scientist in the Georgia Tech Research Institute (GTRI). In U.S. News Map, each instance of a term that appeared in the newspapers is represented with a dot, and lighter dots indicate multiple mentions. Users can move a slider to see how terms pop up in different cities and follow a link to images of the newspaper pages. “We’ve placed the data onto a map of the United States that allows users to view how the term moved across the country over time,” Goodyear explained. “You can navigate through time to see how each term was used in different locations. You really get a sense for how ideas went viral during that time in history.” — John Toon

(Top) This newspaper article is among those accessible in the Library of Congress collection, now indexed through U.S. News Map. (Below) The project allows historians and others to track how ideas moved across the United States between 1836 and 1924.

R E S E A R C H H O R I ZO N S 2 3

EXTREME ENERGY

EMERGING TECHNOLOGIES that may help

THE

The world human population is already more than 7 billion — a number that could exceed 11 billion by 2100, according to projections from the United Nations. This rising populace, coupled with environmental challenges, puts even greater pressure on already strained energy resources. Granted, there’s no silver bullet, but Georgia Tech researchers are developing a broad range of technologies to make power more abundant, efficient, and eco-friendly. This feature provides a quick look at a dozen unusual projects that could go beyond traditional energy technologies to help power everything from tiny sensors to homes and businesses.

BY T.J. BECKER PHOTO ILLUSTRATIONS BY ROB FELT & MELANIE GOUX

R E S E A R C H H O R I ZO N S 2 5

NA-TECC: WORTH ITS SALT Shannon Yee, an assistant professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering, is developing a technology that leverages the isothermal expansion of sodium and solar heat to directly generate electricity. Affectionately known as “Na-TECC” (an acronym that combines the chemical symbol for sodium with initials from “Thermo-Electro-Chemical Converter” and also rhymes with “GaTech”), this unique conversion engine has no moving parts. A quick rundown in geek speak: Electricity is generated from solar heat by thermally driving a sodium redox reaction on opposite sides of a solid electrolyte. The resulting positive electrical charges pass through the solid electrolyte due to an electrochemical potential produced by a pressure gradient, while the electrons travel through an external load where electric power is extracted. Bottom line, this new process results in improved efficiency and less heat leaking out, explained Yee. The goal is to reach heat-to-electricity conversion efficiency of more than 45 percent — a substantial increase when compared to 20 percent efficiency for a car engine and 30 percent for most sources on the electric grid. The technology could be used for distributed energy applications. “A Na-TECC engine could sit in your backyard and use heat from the sun to power an entire house,” Yee said. “It can also be used with other heat sources such as natural gas, biomass, and nuclear to directly produce electricity without boiling water and spinning turbines.” Funded by the Department of Energy’s (DOE) SunShot Program, the research is being conducted in collaboration with Ceramatec Inc.

In another project, Yee’s group is using nuclear waste to produce electricity — minus the reactor and sans moving parts. Funded by the Defense Advanced Research Projects Agency (DARPA) and working in collaboration with Stanford University, the researchers have developed a technology that is similar to photovoltaic devices with one big exception: Instead of using photons from the sun, it uses high-energy electrons emitted from nuclear byproducts. Betavoltaic technology has been around since the 1950s, but researchers have focused on tritium or nickel-63 as beta emitters. “Our idea was to revisit the technology from a radiation transport perspective and use strontium-90, a prevalent isotope in nuclear waste,” Yee said. Strontium-90 is unique because it emits two high-energy electrons during its decay process. What’s more, strontium-90’s energy spectrum aligns well with design architecture already used in crystalline silicon solar cells, so it could yield highly efficient conversion devices. In lab-scale tests with electron beam sources, the researchers have been achieving power conversion efficiencies of between 4 and 18 percent. With continued improvements, Yee believes the betavoltaic devices could ultimately generate about one watt of power continuously for 30 years — which would be 40,000 times more energy dense than current lithium ion batteries. Initial applications include military equipment that requires low-power energy for long periods of time or powering devices in remote locations where changing batteries is problematic.

SHANNON YEE Assistant Professor, George W. Woodruff School of Mechanical Engineering

Flexible Generators Yee’s group is also pioneering the use of polymers in thermoelectric generators (TEGs). Solid-state devices that directly convert heat to electricity without moving parts, TEGs are typically made from inorganic semiconductors. Yet polymers are attractive materials due to their flexibility and low thermal conductivity. These qualities enable clever designs for high-performance devices that can operate without active cooling, which would dramatically reduce production costs. The researchers have developed P- and N-type semiconducting polymers with high performing ZT values (an efficiency metric for thermoelectric materials). “We’d like to get to ZT values of 0.5, and we’re currently around 0.1, so we’re not far off,” Yee said. In one project funded by the Air Force Office of Scientific Research, the team has developed a radial TEG that can be wrapped around any hot water pipe to generate electricity from waste heat. Such generators could be used to power light sources or wireless sensor networks that monitor environmental or physical conditions, including temperature and air quality. “Thermoelectrics are still limited to niche applications, but they could displace batteries in some situations,” Yee said. “And the great thing about polymers, we can literally paint or spray material that will generate electricity.” This opens opportunities in wearable devices, including clothing or jewelry that could act as a personal thermostat and send a hot or cold pulse to your body. Granted, this can be done now with inorganic thermoelectrics, but this technology results in bulky ceramic shapes, Yee said. “Plastics and polymers would enable more comfortable, stylish options.” Although not suitable for grid-scale application, such devices could provide significant savings, he added.

YEE: FITRAH HAMID

New Breed of Betavoltaics

“A NA-TECC ENGINE COULD SIT IN YOUR BACKYARD AND USE HEAT FROM THE SUN TO POWER AN ENTIRE HOUSE.”

R E S E A R C H H O R I ZO N S 2 7

“[THE TRIBOELECTRIC SYSTEM] REALLY BROADENS THE NUMBER OF POSSIBLE APPLICATIONS.” ZHONG LIN WANG Regents Professor, School of Materials Science and Engineering

Recycling Radio Waves Researchers led by Manos Tentzeris have developed an electromagnetic energy harvester that can collect enough ambient energy from the radio frequency (RF) spectrum to operate devices for the Internet of Things (IoT), smart skin and smart city sensors, and wearable electronics. Harvesting radio waves is not brand new, but previous efforts have been limited to short-range systems located within meters of the energy source, explained Tentzeris, a professor in Georgia Tech’s School of Electrical and Computer Engineering. His team is the first to demonstrate long-range energy harvesting as far as seven miles from a source. The researchers unveiled their technology in 2012, harvesting tens of microwatts from a single UHF television channel. Since then, they’ve dramatically increased capabilities to collect energy from multiple TV channels, Wi-Fi, cellular, and handheld electronic devices, enabling the system to harvest power in the order of milliwatts. Hallmarks of the technology include:

PICKIN’ UP GOOD VIBRATIONS In another energy harvesting approach, researchers in Georgia Tech’s School of Mechanical Engineering are making advances with piezoelectric energy — converting mechanical strain from ambient vibrations into electricity. Scientists have been exploring this field for more than a decade, but technologies haven’t been widely commercialized because piezoelectric harvesting is very case and application dependent, explained Alper Erturk, an assistant professor of acoustics and dynamics who leads Georgia Tech’s Smart Structures and Dynamical Systems Laboratory. Current piezoelectric energy harvesters rely on linear resonance behavior, and to maximize electrical power, the excitation frequency of ambient sources must match the resonance frequency of the harvester. “Even a slight mismatch results in drastically reduced power output, and there are numerous scenarios where that happens,” Erturk said. In response, Erturk’s group has been

pioneering nonlinear dynamic designs and sophisticated computations to develop wideband piezoelectric energy harvesters that operate over a broad range of frequencies. In fact, one of their recent designs, an M-shaped harvester, can achieve milliwatt level output even for tiny milli-g level vibration inputs — a 660 percent increase in frequency bandwidth compared to linear counterparts. “The nonlinear harvesters also have secondary resonance behavior,” Erturk said, “which could enable frequency up-conversion in MEMS harvesters that suffer from device resonance being higher than ambient vibration frequencies.” Although electrical output from vibration energy harvesters is small, it is still enough to power wireless sensors for structural health monitoring in bridges or aircraft, wearable electronics, or even medical implants. “Piezoelectric harvesting could eliminate the hassle of replacing batteries in many low-power devices — providing cleaner power, greater convenience, and meaningful savings over time,” Erturk said.

R O B F E LT

Power Rubbed the Right Way Triboelectricity enables production of an electrical charge from friction caused by two different materials coming into contact. Although known for centuries, the phenomenon has been largely ignored as an energy source because of its unpredictability. Yet researchers led by Zhong Lin Wang, a Regents Professor in Georgia Tech’s School of Materials Science and Engineering, have created novel triboelectric nanogenerators (TENGs) that combine the triboelectric effect and electrostatic induction. By harvesting random mechanical energy, these generators can continuously operate small electronic devices. The first TENG debuted in 2012. Powered by foot tapping, it generated enough alternating current to power banks of LEDs. Since then the researchers have been pushing the envelope on their technology and have developed a self-charging system that not only converts alternating current to direct current but also features a power management unit that adapts to the variability in human movement. Behind these recent milestones is a two-stage design: First the TENG

Ultra-wideband antennas that can receive a variety of signals in different frequency ranges. Unique charge pumps that optimize charging for arbitrary loads and ambient RF power levels. Antennas and circuitry, 3-D inkjet-printed on paper, plastic, fabric, or organic materials, that are flexible enough to wrap around any surface. (The technology uses principles from origami paper-folding to create “smart” shape-changing complex structures that reconfigure themselves in response to incoming electromagnetic signals.) The researchers have recently adapted the harvester to work with other energy-harvesting devices, creating an intelligent system that probes the environment and chooses the best source of ambient energy to collect. What’s more, it combines different forms of energy, such as kinetic and solar, or electromagnetic and vibration. Although some work remains to scale the printing process, commercialization of the National Science Foundation-supported research could happen within two years.

charges a small capacitor. Then energy is transferred to a final storage device (a larger capacitor or battery) that matches the impedance of the generator’s output and provides appropriate voltage and constant output. Five seconds of palm tapping generates enough current to operate a wireless car door lock. “The power management circuit is key to boosting efficiency,” said Simiao Niu, a graduate student and lead author on a paper recently published in the journal Nature Communications. “Without the circuit, charging efficiency is below 1 percent, but with it we’ve been able to demonstrate efficiencies of 60 percent.” “This really broadens the number of possible applications,” Wang said, pointing to temperature sensors, heart rate monitors, pedometers, watches, scientific calculators, and RF wireless transmitters. Although the self-powered system was initially developed to capture human biomechanical energy, the researchers have created four different modes to convert other ambient sources of mechanical energy, such as ocean waves, wind blowing, keyboard strokes, and tire rotation. R E S E A R C H H O R I ZO N S 2 9

A carbon nanotube optical rectenna converts green laser light to electricity in the laboratory of Baratunde Cola at Georgia Tech.

Researchers led by Baratunde Cola, an associate professor in Georgia Tech’s School of Mechanical Engineering, have developed the first known optical rectenna — a technology that could be more efficient than today’s solar cells and less expensive. Rectennas, which are part antenna and part rectifier, convert electromagnetic energy into direct electrical current. The basic idea has been around since the 1960s, but Cola’s team makes it possible with nanoscale fabrication techniques and different physics. “Instead of converting particles of light, which is what solar cells do, we’re converting waves of light,” he explained. Key to this technology are antennas small enough to match the wavelength of light (about one micron) and a super-fast diode — achieved in part by building the antenna on one of the metals in the diode. Cola describes the process: Carbon nanotubes are grown vertically off a substrate. Using atomic layer deposition, the nanotubes are coated with aluminum oxide to serve as an insulator. Extremely thin layers of calcium and aluminum metals are placed on top to act as an anode. As light hits the carbon nanotubes, a charge moves through the rectifier, which switches on and off to create a small direct current. The metal-insulator-metal-diode structure is fast enough to open and close at a rate of 1 quadrillion times per second. From a performance perspective, the devices currently operate just under 1 percent efficiency. Yet because theory matches lab experiments, Cola hopes to increase broad-spectrum efficiency to 40 percent (which compares to 20 percent efficiency for silicon solar cells). Other important benefits: The optical rectenna works at high temperatures, and mass production should be inexpensive. The technology also can be tuned to different frequencies, so the rectenna can be used as a detector or in energy harvesting. The researchers are now focused on lowering contact resistance and growing the nanotubes on flexible substrates for applications that require bending. The work has been supported by DARPA, the Space and Naval Warfare Systems Center, and the Army Research Office. 30

Pulp Energy Although fossil-fuel emissions may be the poster child for global warming, there is also growing concern over environmental harm from discarded electronics. Researchers at Georgia Tech’s Center for Organic Photonics and Electronics (COPE) and Renewable Bioproducts Institute are developing paper-based electronics — organic solar cells, organic light-emitting diodes (OLEDs), and organic field-effect transistors (OFETs) — fabricated on cellulose-based substrates that can be recycled easily. Use of paper for substrates has generated considerable buzz among researchers, but its high porosity and surface roughness pose challenges. Today’s organic electronic components use very thin carbon-based semiconductor layers — about 1,000 times thinner than the average human hair. “Because they are so thin, you need nearly atomically flat substrates where the surface is down to a nanometer,” explained Bernard Kippelen, director of COPE and a professor in Georgia Tech’s School of Electrical and Computer Engineering. To address this, Kippelen’s team is using cellulose nanocrystals (CNCs), a type of wooden wunderkind material, to develop new semiconductor devices, demonstrating that CNCs are a viable alternative to traditional plastic substrates — while offering new environmental benefits. Devices made on these substrates can be easily dissolved in water, allowing semiconducting materials and metal layers to be filtered and recycled. Applications will depend on economics and performance. For CNCbased solar cells, the researchers have achieved power conversion efficiencies of 4 percent. Efficiencies could be increased to 10 percent but would require more expensive materials, Kippelen said. So instead of paper-based solar farms becoming the norm, he predicts low-power applications, such as computer covers and mousepads, for CNC-based solar cells. Cellulose-based OLEDs, which have performance comparable with current devices, show greater potential for market adoption. “The trend in flat-panel displays is larger size and higher resolution,” Kippelen said. “Glass substrates, however, pose manufacturing and transportation problems because of their rigidity and breakability. And plastic has problems at the end-of-product lifecycle.” Yet with the low cost and flexibility of paper-based OLEDs, flat panel displays could be the size of a wall.

R O B F E LT

OPTICAL RECTENNA

“THIS NEW BREED OF SUPERCAPS COULD REPLACE BATTERIES.”

MEILIN LIU

Fuel from the Sky

Regents Professor, School of Materials Science and Engineering

In another intriguing project, researchers led by Peter Loutzenhiser are leveraging solar energy to reverse the combustion process and produce synthesis gas (mixtures of hydrogen, carbon monoxide, and small amounts of carbon dioxide), which can be converted into fuels such as kerosene and gasoline. “Instead of using fossil resources to create fuel, we are using the byproducts of combustion (water and carbon dioxide) to re-energize the system with the sun,” explained Loutzenhiser, an assistant professor at Georgia Tech’s School of Mechanical Engineering. HELLO The researchers are studying a twostep process using metal oxides that can split water and carbon dioxide. The first step, which occurs between 1100 and 1800 degrees Celsius, thermally reduces or “pulls off” oxygen from the metal oxide material. Then at temperatures of about 300 to 900 degrees Celsius, either water or carbon dioxide is introduced in the second step. These lower temperatures are favorable for re-oxidation, which enables the metal oxide to take back oxygen from either the water or carbon dioxide, resulting in hydrogen or carbon monoxide. “The two steps are important — otherwise the oxygen would recombine with either the carbon monoxide or hydrogen, resulting in the release of heat that would then be lost,” Loutzenhiser said. The researchers have demonstrated that the technology works with zinc oxide, but they are searching for materials that can speed up the reactions and reduce the temperature of the first step. “You want something that can reduce at the lowest possible temperature in the high-temp stage and is capable of taking the oxygen from the carbon dioxide or the water vapor in the second step,” Loutzenhiser explained. Recently, the group achieved promising results with mixed ionic electronic conducting materials. Now they are trying to tune these materials to break apart either the CO2 molecules or the water vapor molecules at lower temperatures. If commercialized, the technology could transform desert areas into fuel farms, Loutzenhiser said: “Instead of pulling fuel out of the ground, we could pull carbon dioxide from the air and use the sun to convert it with water into a long-term storage medium that could be shipped and used around the world without changes to transportation infrastructure.”

GRAPHENE SUPERCAPS, GOOD-BYE BATTERIES?

FITRAH HAMID

Used in everything from military applications to elevators and cars, supercapacitors are attractive sources for clean energy because they quickly charge and discharge and have long cycling lives. But there’s one big drawback: low energy density. “Today’s supercapacitors have only one-tenth the energy density of lithium-ion batteries,” pointed out Meilin Liu, a Regents Professor in Georgia Tech’s School of Materials Science and Engineering. “For the device to give you the same electrical energy, the device would have to be much bigger.” Working with C.P. Wong, another Regents Professor, Liu is developing graphene-based supercapacitors that offer significantly increased energy density while maintaining high power and long operational life. The research is funded by ARPA-E. Graphene is a two-dimensional material that conducts electricity better than copper and is both lighter than steel and 100 times stronger. Yet graphene has a tendency to stack together and form graphite. To prevent this, the researchers place molecular spacers between the graphene sheets, creating a 3-D porous structure that demonstrates a capacitance of 400 Faradays per gram — four times higher than current supercaps. The researchers have also improved capacitance by dispersing transition

metal compounds into the graphenebased structure. Graphene alone can only produce a capacitance of about 400 Faradays per gram of material. In contrast, transition metal compounds have higher energy density (2,000 to 3,000 Faradays per gram), but poor electronic connectivity, which slows down the flow of electrons required for charging and discharging. Yet by combining the metal compounds with the 3-D porous graphene, which scores high marks for connectivity, the researchers have achieved capacitance of about 1,500 Faradays per gram while maintaining superior cycling. The researchers are also improving energy density by broadening voltage using two different electrode materials (one positive and one negative). “Each redox material has its own operating window of potential, and we optimize the nanostructure to achieve their highest energy density,” Liu explained. With these new developments, the researchers are approaching supercaps that can be as small as batteries, but charged and discharged faster and cycled for much longer, Liu said. “This new breed of supercaps could replace batteries, providing cleaner, safer, and more robust power for many applications, from portable electronics to electric vehicles and smart grids.”

R E S E A R C H H O R I ZO N S 3 1

MONOLITHIC MICROSCALE HEAT PUMPS

No synthetic refrigerants are used, and less fluid is required, which further lowers costs and increases safety. No compressor is needed and there are few moving parts, decreasing noise and increasing reliability. Modular design allows units to be configured to generate anywhere from a few watts to tens of kilowatts of cooling or heating. Since unveiling a proof-of-concept unit in 2009, the researchers have developed heat pumps with cooling capacities of one and two refrigerant tons. (Capacity of current residential units ranges from one to four refrigerant tons.) Efficiency has been

Next-gen Power Plants

T.J. Becker is a freelance writer based in Michigan. She writes about business and technology issues. 32

substantially improved, and fabrication techniques have also been improved to enable mass production. “Although initial cost to consumers might be higher than traditional heat pumps, lifecycle costs should be comparable because of lower operating costs,” Garimella said, noting that field tests are slated for late this year, and the technology might be ready for commercialization by 2017. The researchers have also adapted the technology to provide cooling using waste heat from diesel-driven generators at military bases, where ambient temperatures are extremely high. “Not only is diesel fuel very expensive to transport, there are also risks to humans in delivering the fuel,” Garimella said. “Using the energy in the diesel fuel to the fullest extent by providing power as well as cooling through these units, without consuming additional prime energy, will lower overall costs and increase personnel safety.” The research has been supported by ARPA-E, Department of Energy, U.S. Army, Naval Facilities Engineering Command, Georgia Research Alliance, and Atlanta Gas Light.

Researchers in Georgia Tech’s School of Mechanical Engineering are working on major makeovers for power plants, introducing innovations that range from revamped power cycles to new infrastructure materials. In one project, steam is being replaced with supercritical carbon dioxide (SCCO2 ) as the working fluid to operate turbines and produce electricity. SCCO2 results when carbon dioxide is subjected to pressure above 7.4 megapascals and temperatures above 31 degrees Celsius. This magical state, somewhere between a liquid and a gas, provides high fluid density, thermal conductivity, and heat capacity. SCCO2 is currently used in environmentally friendly dry cleaning and coffee decaffeination. In energy applications, its high density and compressibility would enable generators to extract more power from turbines, explained Devesh Ranjan, an associate professor of fluid mechanics. “Equipment could be made from top-notch materials, yet dramatically smaller, which would reduce production costs.” Another plus: the unique cooling properties of SCCO2 . “Most power plants are near a lake or river because they need lots of water to cool them,” Ranjan said. “Because the heat transfer coefficient is very high with SCCO2 , you can do dry cooling in an arid environment such as the desert, which is best for solar collection.” Using SCCO2 in concentrated solar plants could push thermal efficiencies from 45 to 60 percent, enough to be competitive

with fossil fuel, said Asegun Henry, an assistant professor of heat transfer, combustion, and energy systems. “Yet this requires higher operating temperatures — 800 degrees Celsius compared to current temperatures below 600 degrees — and current heat exchangers literally can’t take the pressure.” To resolve this, Henry and Ranjan are working with Purdue University researchers to develop a new breed of heat exchanger that can withstand extremely high temperatures and pressures, a project supported by DOE SunShot funding. Ken Sandhage, a former Georgia Tech professor now at Purdue’s School of Material Engineering, has developed a process for inexpensively fabricating a high-temperature composite material into complicated 3-D shapes. In addition to making solar power more competitive, the heat exchangers could also be used with SCCO2 to boost efficiency in fossil fuel power plants. “More efficiency means less carbon dioxide emissions per kilowatt produced,” Henry said.

COURTESY SRINIVAS GARIMELLA

Proving that good things come in small packages, researchers led by Srinivas Garimella have developed a novel textbook-sized cooling system that operates on waste heat rather than electricity. The underlying technology has been used in very large-scale installations, such as hospitals and university campuses, explained Garimella, a professor in Georgia Tech’s School of Mechanical Engineering. Yet his team takes the science to a new level by working at the micro scale and creating a self-contained unit. How it works: Extremely small passages are etched into thin sheets of metal with different areas representing different components. Working fluids flow in the same order as they would in a larger system, albeit in one space. The minimization of plumbing inlets and outlets translates into greater compactness — and lower price tags. Other advantages:

“BECAUSE THE HEAT TRANSFER COEFFICIENT IS VERY HIGH WITH SCCO2 , YOU CAN DO DRY COOLING IN AN ARID ENVIRONMENT.” DEVESH RANJAN Associate Professor, George W. Woodruff School of Mechanical Engineering

GARY MEEK

R E S E A R C H H O R I ZO N S 3 3

ROLLING ROBOTS RESEARCHERS WORK TO AVOID POTHOLES AND PITFALLS ON THE ROAD TO AUTONOMOUS VEHICLES

BY RICK ROBINSON â&#x20AC;¢ ILLUSTRATION BY TAVIS COBURN

R E S E A R C H H O R I ZO N S 3 5

ogy campus, researchers monitor a scale-model autonomous car as it drifts around corners at a blistering eight meters per second — equivalent to 90 miles per hour in a full-size vehicle. Pushing this car to its limits could help make full-size driverless vehicles more stable in risky road conditions. This unique one-fifth-scale device is just one of many research efforts aimed at helping the autonomous vehicle revolution happen successfully and safely. Self-driving cars are unquestionably coming, guided variously by radar, lidar, motion sensors, cameras, GPS, and plenty of onboard computation. Already, semi-autonomous prototypes are operating under controlled conditions in California, and speculation about future autonomy includes visions of commuters napping through drive-time, high-speed convoys of networked big-rigs, and a huge drop in accidents as robotic vehicles take over from impaired and distracted humans. Yet these are only visions, where generalizations rule and few facts are established. At Georgia Tech, research focuses on the elusive but critical details of this phenomenon, as investigators from disciplines as diverse as industrial systems, design, engineering, computing, and psychology are developing a roadmap to robotic vehicles. Researchers at Georgia Tech generally agree that a long period of adjustment, including generations of semi-autonomous vehicles, will be needed to reach completely autonomous transport on a large scale. Estimates of the time required vary from a couple of decades to more than half a century. “Fully autonomous transport will require absolutely reliable navigation systems, major changes in highway infrastructure, and traffic control that’s synched to the vehicle, plus new fueling, insurance, financing, and manufacturing paradigms,” said Vivek Ghosal, a professor in Georgia Tech’s School of Economics, who studies the automotive industry. “Yes, we have prototypes, but the operationalizing of autonomy is still far away.” A four-level model of the vehicular-automation process is now widely accepted. Level one denotes today’s driver-dependent cars; level two involves intelligent cruise and lane control with some automatic braking; level three indicates semi-autonomous vehicles that drive themselves but cede control to a human when conditions demand; and level four means fully autonomous with no driver controls. Researchers at Georgia Tech, focusing on the gritty details, have spotlighted a list of complications that include:

Human-machine interaction issues. Costly highway infrastructure changes. Unpredictable traffic effects. Conflicts between self-driving and human-driven vehicles. Guidance system reliability concerns. Vehicle ownership, liability, and business model shifts. Potential for major changes to the urban landscape.

This article takes a look at some of the research currently underway at Georgia Tech related to self-driving vehicles. 36

At the Georgia Tech Autonomous Racing Facility, researchers are studying a onefifth-scale autonomous vehicle as it traverses a dirt track. The work will help the engineers understand how to help driverless vehicles face the risky and unusual road conditions of the real world.

R O B F E LT

AT A DIRT TEST TRACK near the Georgia Institute of Technol-

CAR-DRIVER COOPERATION Many researchers believe semi-autonomous vehicles will dominate during the years or decades needed to sort out the complexities of fully autonomous transport. One key question: How can a semi-autonomous car or truck share driving responsibilities with people smoothly and safely? At Georgia Tech’s Sonification Laboratory, Professor Bruce Walker pursues studies on the use of sound to convey information to people whose eyes are otherwise engaged — a surgeon focused on a procedure or a firefighter hampered by smoke. Walker, who serves jointly in the School of Psychology and School of Interactive Computing with a focus on engineering psychology, is testing interface approaches that would allow a human riding in a semi-autonomous car to search the Web or read a book while also staying reliably informed about vehicle operation. One key research area focuses on situational awareness, explained Walker, a member of Georgia Tech’s GVU Center as well as its Institute for People and Technology. Drivers of conventional cars must be constantly aware just to stay in a lane, but in a semi-autonomous vehicle with features like advanced lane control, occupants could work and play without much regard for the road or other drivers. “Inevitably, however, there are going to be situations where the autonomous processes — the computer vision, the guidance smarts, the GPS signal — will fail and control has to be handed off to a human,” he said. “The system needs to be able to keep the driver informed of any potential problems — my contention is that we can never let the driver lose situational awareness.” Critical to maintaining this shared awareness is developing ways for a semi-autonomous guidance system to monitor itself — essentially, to maintain confidence in its own ability to handle what’s ahead. Under this approach, when a guidance system’s self-confidence falls below a certain point, the vehicle will alert the driver to take over. To achieve effective vehicle-human communication, Walker’s team is

R E S E A R C H H O R I ZO N S 3 7

shouldn’t be so aggressive that they alarm the occupants, or so passive that people become frustrated.”

In the Human- Machine Interface Laboratory, Researcher Wayne Li is building a driving simulator to investigate the role of interior components in the critical task of autonomous-vehicle control.

MODELING MIXED-FLEET CONFLICTS Michael Hunter, an associate professor in Georgia Tech’s School of Civil and Environmental Engineering, uses computer models to study the management and operation of future roadways. His work is looking at a variety of possible traffic scenarios as semi-autonomous and fully autonomous vehicles become a reality. Hunter directs both the University Transportation Center, a research effort sponsored by the U.S. Department of

R O B F E LT

testing a wide variety of background sounds. The researchers are weighing different approaches for conveying escalating levels of concern, from “all systems go” to “intervention needed.” The goal is to keep drivers in the loop without alarming them. To assess how test subjects interact with multiple scenarios, the team is using three driving simulators, including a miniSim testbed devised by the National Advanced Driving Simulator group at the University of Iowa. This realistic setup combines advanced software with full-size control pedals and steering wheel, multiple plasma screens, and even a genuine car seat. Eye-tracking equipment and physical response monitors track a user’s interactions with the visual driving routines. Panasonic Automotive, currently a dominant producer of automotive control systems such as cruise control, has been paying close attention to Walker’s work. John Avery, engineering group manager for the Panasonic Innovation Center in Georgia Tech’s Technology Square, acknowledges such research could be relevant to the company’s future activities in advanced driver assistance systems. “It’s important that semi-autonomous cars drive in a way that makes humans comfortable,” Avery said. “Their driving style

DEVELOPING CONTROL LANGUAGE Driving simulators are valuable tools for autonomous vehicle research. In the Human-Machine Interface Laboratory, Wayne Li is investigating the role of interior components in the critical task of autonomous-vehicle control. He wants to know how control language — what people see, feel, and touch inside a vehicle — can make users confident even when they don’t have conventional full control. Li is working with a Georgia Tech-built testbed consisting of parts of a 2010 Chevy Malibu mounted on a highly adjustable aluminum frame. The setup uses special software along with multiple screens and eye-tracking sensors to gauge user reactions. The system, installed at the College of Architecture, is a joint effort of Georgia Tech’s School of Industrial Design, where Li is the Oliver Endowed Professor of Practice, and the School of Mechanical Engineering, School of Interactive Computing, and School of Psychology. The project is funded by General Motors Corp. “Our work involves exploring the different types of control schema that will function best as we move toward level three semi-autonomous and level four autonomous cars,” Li said. “Maybe at level three there’s no steering wheel anymore — maybe it’s a joystick — and maybe there’s no speedometer or instrument cluster either, since a semi-autonomous car would automatically obey speed limits.” The Human-Machine Interface group cooperates with Bruce Walker’s Sonification Lab, sharing assessment tools and expertise. Both labs use miniSim software from the National Advanced Driving Simulator group to help support their testbeds’ simulation and evaluation capabilities. Li envisions cars with semi-transparent windshields that give a view of the road while also providing important vehicle information along with email, Web pages, and video. If the windshield images suddenly disappear, it could be a signal to the person in the driver’s seat to prepare to take over. “The automatic transmission, which first appeared about 1950, was a terrible design, and it took decades for it to improve to the point where in the U.S. it has almost full acceptance,” Li said. “Autonomy is going to be the same way — acceptance will be gradual. But 60 years or so from now cars will really drive themselves, and we’ll just lounge around doing what we want.”

Transportation that involves Georgia Tech and three partner universities; and the Georgia Transportation Institute, which helps coordinate transportation research with the Georgia Department of Transportation. His work has thus far turned up concerns that include: Disruption and danger: The presence of autonomous cars on roadways could disrupt traffic flow for a number of reasons. Robotic cars, programmed to prioritize safety, would give way to aggressively driven conventional cars. That could become a big problem at rush hour, for example, as drivers entering a highway may find they can cut off the distinctive-looking self-driven vehicles, creating shockwaves that slow or stop traffic. Worse, irresponsible drivers or pedestrians, knowing how autonomous vehicles are programmed, might play dangerous games that involve physically challenging the robots to make them swerve away. Surface street bottlenecks: Multiple studies forecast that highly responsive autonomous technology will increase traffic flow on main arteries, with cars and trucks traveling in tight, high-speed formations that respond instantly to changes in speed or conditions. But one result could be gridlock when this greater volume of vehicles hits city streets that still use conventional traffic signals. Legislative gridlock: The potential problems between autonomous and driven vehicles could someday spark legislative efforts to ban driven cars, a move that’s sure to be controversial. “I am highly doubtful that any government entities would ban human beings from driving for the foreseeable future,” Hunter said. “This is not going to be a shortterm transition. A mixed fleet of human-driven and robotic vehicles — with any number of issues and challenges — is going to be the long-term state of the system.”

AUTONOMOUS RACING TEST TRACK A collaborative research team is using scale-model racing cars to explore methods for keeping an autonomous car under control — or rather to help it keep itself under control. At the Georgia Tech Autonomous Racing Facility, researchers from the School of Interactive Computing (IC) and the Daniel Guggenheim School of Aerospace Engineering (AE) are racing, sliding, and jumping these one-fifth-scale cars at the equivalent of 90 mph. The goal: to develop maneuvering techniques that can keep an autonomous vehicle on the road and its occupants safe. James Rehg, a professor in IC, is collaborating on the race track studies with Professor Panagiotis Tsiotras and Assistant Professor Evangelos Theodorou, both of AE. The work is sponsored by the U.S. Army Research Office. Two cars — custom built by the team — use powerful graphics processing units (GPUs) onboard to supply the computation necessary for autonomous navigation and data capture. Using GPS-based guidance, multiple parallel GPUs employ advanced mathematical techniques to provide the real-time functionality needed for autonomous control at high speeds. Inertial measurement sensors provide additional velocity data. “Our vehicles are unique because they’re fully autonomous — there’s no tether, no radio connection, and all data processing is done on the vehicle,” said Rehg, who is a member of the Institute for Robotics and Intelligent Machines at Georgia Tech. “We know of studies that are using full-size racing cars and human drivers, but there are some clear advantages to being smaller — we can

maneuver our cars very aggressively, and if we crash, no one’s hurt and it’s easy and low-cost to replace the components.” Computers, he added, can readily convert the information collected from these small cars, so that their performance data becomes comparable to the performance expected from a fullsize vehicle. Designing and building the project’s vehicles was a complex undertaking. Challenges included integrating the onboard computer, sensors, actuators, and software so they work together seamlessly and robustly. The team used gasoline engines at

“THE AUTOMATIC TRANSMISSION, WHICH FIRST APPEARED ABOUT 1950, WAS A TERRIBLE DESIGN, AND IT TOOK DECADES FOR IT TO IMPROVE TO THE POINT WHERE IN THE U.S. IT HAS ALMOST FULL ACCEPTANCE. AUTONOMY IS GOING TO BE THE SAME WAY —

ACCEPTANCE WILL BE GRADUAL.” first, but later turned to electric motors that combine small size with plenty of power. In one series of experiments, the researchers utilized maneuvers used by rally car drivers to control vehicles during a jump. The team was able to program these techniques — which control landings by spinning or slowing a vehicle’s wheels in mid-air — into the guidance systems of its autonomous cars. Other efforts include vision-based control for autonomous vehicles to augment GPS guidance, and the ability for vehicles to anticipate deadly T-bone collisions before impact and then maneuver automatically to better protect occupants. “An autonomous vehicle should be able to handle any condition, not just drive on the highway under normal conditions,” said Tsiotras, an expert on the mathematics behind rally car racing. “One of our principal goals is to infuse some of the expert techniques of human drivers into the brains of these autonomous vehicles.”

EXPLOITING THE ELECTRIC GRID The autonomous vehicles of the future may be powered largely by electric engines, which offer energy advantages in stop-and-go urban driving. If so, the presence of millions of high-capacity car batteries could have major implications for the U.S. electric grid. Valerie Thomas, who researches renewable energy, is studying the interplay between electric vehicles and the grid. She notes that plugging in a host of electric vehicles could increase the U.S. system’s flexibility. Electric vehicles are often plugged in when not in use, allowing them to charge with under-utilized R E S E A R C H H O R I ZO N S 3 9

IMPROVING DRIVER ASSISTANCE Many driver-controlled cars are now equipped with sensors — including cameras, radar, and laser proximity devices — that detect nearby vehicles and other aspects of the environment. These level-two driver-assistance systems log vast quantities of data on active cruise control, automatic braking, lane changes, and other performance elements. Byron Boots, an assistant professor in Georgia Tech’s School of Interactive Computing, is performing statistical analysis on sensor data from a large fleet of level-two vehicles with driver-assistance capabilities. Working with sponsor BMW AG, Boots and his team are investigating the cars’ ability to predict when a potentially hazardous event is imminent and then effectively communicate the situation. Driver assistance, Boots said, is getting a lot of attention from many car makers. Companies are exploring the theory that advising the driver of impending danger could result in a better driving experience than having control suddenly — and alarmingly — wrested away. “For example, you may be entering a near-miss situation where another vehicle is about to merge into your lane, cutting you off,” Boots said. “If your car can perceive the other vehicles on the road and use machine learning to predict the dangerous situation before it happens, it could instantly advise the driver of the hazard rather than just taking over control. That approach may not just help to make transportation safer, but also help convince people that automation really is able to protect them.” BRIEFING THE GOVERNMENT The advent of autonomous transport has the attention of government. Sebastian Pokutta, who is David M. McKenney Family Assistant Professor in Georgia Tech’s School of Industrial & Systems Engineering, recently co-authored a white paper for the Computing Community Consortium that was presented to White House representatives and others at a National Science Foundation workshop. “Many automakers believe that by 2020 we can have fully functional autonomous vehicles on the road,” Pokutta said. “But for that to happen, there have to be legislative and policy decisions that address a number of critical technology, infrastructure, and other issues.” Some of the key points in Pokutta’s analysis include: High-speed platooning of cars and trucks could translate into faster commute times. That in turn could add to urban sprawl 40

as people move farther out into the hinterlands. Moreover, car sharing could mean that vehicles will be continually in use, lowering demand for parking and potentially changing urban land use. Self-driving prototypes rely heavily on special physical and mapping infrastructure. Extensive investment will be required to bring those kinds of infrastructure changes to the whole nation or to find other ways to overcome these limitations. Even then, self-driving cars may lose their bearings in unexpected situations such as construction, detours, road closures, or unusual weather conditions. The GPS-dependent mapping systems that guide autonomous vehicles must be made 100 percent reliable. If signals cut out in bad weather, under bridges, or inside buildings and tunnels, serious problems could ensue. “One huge benefit from self-driving vehicles could be a major reduction in traffic accidents. Every year 40,000 people die on U.S. roads, and drunk driving results in an estimated $200 billion in costs,” Pokutta said. “Autonomous systems taking control away from impaired or deranged operators — in trains and aircraft as well as motor vehicles — could save many lives and a great deal of money.”

PLANNING FOR FREIGHT-VEHICLE AUTONOMY Increasing automation won’t affect only cars. Freight vehicles of every type, from tractor-trailers to delivery trucks, will also be changed by autonomy in ways that aren’t yet known. A team led by Catherine Ross, Harry West Professor in Georgia Tech’s School of City and Regional Planning (SCaRP), and Tim Welch, an assistant professor in SCaRP, is investigating what may happen as freight vehicles adopt technology that lets them communicate with one another. They could start to drive in tightly packed groups — including high-speed convoys on interstate roads — and follow more efficient routes based on real-time road conditions. “Eventually the entire human aspect of many freight deliveries — or at least the travel part of them — could become autonomous,” Welch said. “We’re studying what that development may look like in the next five, 10, or 15 years.” Planners will have to develop new approaches to make current road systems more adaptable to autonomous traffic movement. And policies and legislation will be needed to enable the construction of new highway and street infrastructure to accommodate the coming changes over the long term. The team is working under a grant from the Transportation Research Board, which is part of the National Academies of Science under the National Cooperative Highway Research Program. The project, a joint effort with Booz Allen Hamilton Inc., is a national research effort. “The time horizon for a fully autonomous fleet of any vehicles, passenger or freight, is going to be a pretty long one,” Welch said. “Managing that entire process over the long term is going to be a challenging task.” ANTICIPATING MARKET CHANGES Vivek Ghosal believes that once the autonomous revolution becomes established, the economic world that underpins wheeled transport will never be the same. Ownership, liability, and manufacturing paradigms could all change in major ways. And, like others, he believes the conversion process will be costly and that both government and industry will have to

The presence of millions of high- capacity car batteries could have major implications for the U.S. electric grid. Valerie Thomas, who researches renewable energy, is studying the interplay between electric vehicles and the grid.

FITRAH HAMID

power — late at night as demand goes down, or when wind power is high, or on sunny days with high solar power. By using the excess power of the grid, the presence of myriad electric vehicles could result in lower electricity costs, said Thomas, who is Anderson Interface Professor of Natural Systems in Georgia Tech’s H. Milton Stewart School of Industrial & Systems Engineering and has a joint appointment in Georgia Tech’s School of Public Policy. “Some have argued that electric vehicles’ flexibility means they’ll be consuming mostly ‘dirty’ power such as low-cost coal-generated power,” Thomas said. “But our studies have found the opposite — these vehicles’ flexibility lets them take advantage of renewable electricity when it is available, and to a large degree can solve the problem of the intermittency of wind and solar.” And if charged car batteries could send some electricity back into the grid when required, smoothing out power crunches, there could be additional cost savings for all electricity users.

pick up a very large bill. Whether cars are semi-autonomous or fully autonomous, electric or fuel cell powered, they’ll require wide-scale improvements in roads, traffic signals and controls, road markings, and signage. They’ll also need a vast charging/ fueling infrastructure that today barely exists. “Even if you could let level-four autonomous cars out on the streets right now, there would be serious problems,” said Ghosal, an auto industry specialist who is Richard and Mary Inman Professor in Georgia Tech’s School of Economics. “Major infrastructure investments are needed to operationalize this technology.” Observations from Ghosal’s research include: Ownership of cars could be substantially reduced under an autonomy-centered paradigm. Even today, car-sharing markets in Europe are expanding quickly, and major car makers there are scrambling to compete with Car2Go, Zipcar, and others. The combination of quickly available level-four cars and extensive car sharing will likely produce lower demand for personally owned automobiles. Changes in ownership patterns will likely propel current automotive, lending, and insurance markets into unmapped

territory, as consumers gradually learn to regard cars as a transportation service rather than a purchase. Self-driving vehicles are essentially information technology-enabled devices, a fact that software companies realize. Ghosal believes the autonomous prototypes being developed by companies like Google and Apple aren’t aimed at starting new car manufacturing corporations but are instead focused on developing definitive operating systems for autonomous control. This proprietary software could become a costly necessity for established automotive manufacturers as they evolve driverless vehicles. Said Ghosal: “This is perhaps the most significant disruption in this industry since the invention of the assembly line by Ford.” One thing is certain: The self-driving revolution is on its way. What isn’t known is what form it will take as it becomes a reality. Georgia Tech research teams will continue to study and develop effective real-world approaches as the transformation continues. Rick Robinson is a science and technology writer in Georgia Tech’s Institute Communications. He has been writing about defense, electronics, and other technology for more than 20 years. R E S E A R C H H O R I ZO N S 4 1

cooler runnings INNOVATION ADDRESSES RISING THERMAL CHALLENGES IN MOBILE DEVICES, COMPUTERS, AND DATA CENTERS BY JOHN TOON

Georgia Techâ&#x20AC;&#x2122;s data center simulator uses lasers, wireless sensors, and other equipment to study air flow and cooling in server racks. Shown is Yogendra Joshi, a professor in Georgia Techâ&#x20AC;&#x2122;s School of Mechanical Engineering. R O B F E LT

R E S E A R C H H O R I ZO N S 4 3

to improve the performance of mobile devices such as smartphones, extending battery life is just one part of the effort. System designers must increasingly worry about removing heat, an unwanted byproduct of watching a YouTube video, shooting a selfie, or updating a Facebook page. In the same way that physical limits on the size of transistors may throttle the performance growth promised by Moore’s Law (the expectation that computer processing power will double about every two years), the challenge of removing heat from eversmaller transistors also poses a threat to continued efficiency improvements. The resulting tradeoffs will affect everything that relies on integrated circuits — from mobile phones and tablets all the way up to high-performance computers and data centers the size of football fields. At Georgia Tech, researchers are addressing these thermal challenges in broad and bold ways. Their efforts include designing chips that operate with less power, providing new forms of cooling, and optimizing data center operations. “The challenges on the small scale are very different from the challenges at the large scale,” said Yogendra Joshi, a professor in Georgia Tech’s George W. Woodruff School of Mechanical Engineering, whose research group studies thermal challenges in a comprehensive way. “Everyone wants more capabilities in the devices they are using, but there are tradeoffs to be made at each level.”

DESIGNING CHIPS FOR THERMAL MANAGEMENT

The whirring fan of a laptop computer is the closest most consumers come to the challenge of thermal management in electronic devices. But the issue really begins much deeper in whatever system they are using, with the design of integrated circuits. In these ICs, billions of transistors carry out computer operations using electrical charges, producing heat that must be removed. Designers must prevent chip temperatures from going beyond levels that can cause a silicon meltdown. But even temperatures below the damage threshold can cause current leakage and reduce performance, so thermal issues have become a critical component of modern IC design. “Until recently, whenever transistors became smaller, they required correspondingly less energy, so you could double the number of transistors on an integrated circuit and the power density remained roughly constant,” noted Sudhakar Yalamanchili, a Regents Professor in Georgia Tech’s School of Electrical and Computer Engineering. “Around the middle part of the last decade, this changed for reasons rooted in physics and technology. Now, as we double the number of transistors, the on-chip power density increases. This is not sustainable because eventually we will get to the point where we cannot cool the devices.” The world’s information technology industry has grown accustomed to continual performance increases that boost productivity. Researchers like Yalamanchili are looking at new computing techniques to continue that beneficial trend. 44

“There is only so much heat that you can extract from a device cost-effectively, and that is how much power you can burn in that much volume,” he said. “The amount of power you can burn, in turn, determines how much the transistors can consume, which controls how many transistors you can operate concurrently. And the number of active transistors determines how much performance you can get.” There are strategies for getting the most out of the available energy. One is increasing the use of special-purpose accelerators that are more efficient than general-purpose chips for certain applications; for example, rewriting code to use graphics processing units (GPUs), the more energy-efficient processors originally developed to handle graphics. Another is reducing the movement of data on chips, a strategy of special interest to Yalamanchili. “Moving a data bit will soon take more energy than the computing operations performed with it,” he explained. “We have to minimize data movement, and this will be a fundamental shift in how computing is done. To continue performance scaling with Moore’s Law, we are going to have to redesign systems to be centered around data and memory systems rather than the CPU.” Other strategies may involve implementing alternative computing models such as neural networks, inspired by our understanding of how the brain operates. Also, new materials and devices such as conducting films and carbon nanotubes may replace traditional complementary metal oxide semiconductorbased systems. Ultimately, the future of computing will depend on a different set of tradeoffs, with energy use — governed by cooling — an increasingly important driver. “It’s now an interdisciplinary research need,” Yalamanchili said. “You have to be able to understand the characteristics of devices, the design of architectures, the demands of applications, and the physics of the overall environment. Industry wants to keep that performance scaling going, and to do that, we are going to have to be more cross-disciplinary.”

COOLING MOBILE DEVICES

It seems there’s now a smartphone in nearly every pocket or purse. These handheld computers can run basic business applications, shoot video, give directions, play games, browse the Web, gather weather updates, send email — and even make phone calls. Battery life for these mobile devices can be a major issue for heavy users, but addressing the power challenge is much more complex than it seems. Smartphones and tablet computers have only the most rudimentary passive cooling capabilities: Heat flows to the case, where it dissipates to the environment — or to the user’s body. So having more battery power won’t necessarily translate into more performance. “The thermal management options for these small devices, both phones and tablets, are extremely limited,” Joshi noted. “You can’t have a fan and you can’t have a heat sink. There are some real physical limits on what you can do related to the amount of physical space available and how tightly the components are packed. That limits the performance you can get.”

“WE HAVE TO MINIMIZE DATA MOVEMENT, AND THIS WILL BE A FUNDAMENTAL SHIFT IN HOW COMPUTING IS DONE.” Sudhakar Yalamanchili, a Regents Professor in Georgia Tech’s School of Electrical and Computer Engineering, is studying how design can address thermal issues in integrated circuits. FITRAH HAMID

In the struggle

R E S E A R C H H O R I ZO N S 4 5

“WHAT WE HAVE DONE SO FAR IS TO SHOW THAT THERE IS A PATHWAY FOR BRINGING MICROFLUIDICS INTO THIS MOBILE COOLING ENVIRONMENT.” Georgia Tech researchers have achieved what is believed to be the first microfluidic cooling of a commercial system-onchip for a mobile device. The liquid cooling reduced energy use by 15 to 20 percent.

The temperature of the device case must be kept low enough — less than about 45 degrees Celsius — to avoid alarming users, while internal temperatures have to remain low enough to avoid damage. Only a few watts of power can heat phones to those limits. One possible solution has been developed in a laboratory led by Joshi and Saibal Mukhopadhyay, where then-Ph.D. students Wen Yueh and Zhimin Wan have achieved what is believed to be the first microfluidic cooling of a commercial system-on-chip for a mobile device. Using deionized water circulated by a tiny piezoelectric pump, the experimenters showed that liquid cooling could reduce energy use by 15 to 20 percent — even after accounting for the pump power — by keeping the chip running cooler. Though the cooling system isn’t yet fully integrated within the device case, it is serving as a test bed for liquid cooling in mobile platforms, said Mukhopadhyay, who is a professor in Georgia Tech’s School of Electrical and Computer Engineering. “For the first time, we were able to show that cooling a mobile processor does help it with overall energy efficiency,” he said. “It helps in terms of performance, and in total power consumed. This fully-controlled system can help us understand how active cooling can help with small devices.” Beyond the performance measures, the cooling system also provided reliability benefits. By controlling the processor operating temperature, the technique kept the chip from shutting down or scaling back its performance even during the highest operational loads. Maintaining lower temperatures should also provide better longterm reliability, Mukhopadhyay said. Among future challenges are miniaturizing the cooling system, developing a control system to turn it on and off, and understanding the implications of using liquids in small electronic devices. Cost issues, however, could slow the transfer of this technology into consumer devices such as smartphones. “What we have done so far is to show that there is a pathway for bringing microfluidics into this mobile cooling environment, but there is a tremendous amount of improvement left to be done,” Mukhopadhyay added. Beyond mobile devices, the work could have implications for robotic vision systems, drones, and other devices that use power-constrained chips in systems with small form

factors. The research was supported by Sandia National Laboratories, the Semiconductor Research Corporation, and Qualcomm.

LIQUID COOLING FOR FPGA CHIPS

R O B F E LT

Graduate student Thomas Sarvey demonstrates an experimental setup that provided liquid cooling directly on an operating high-performance CMOS chip. He worked with School of Electrical and Computer Engineering Professor Muhannad Bakir to implement the technology on a stock field-programmable gate array (FPGA) device.

Using microfluidic passages cut directly into the backs of field-programmable gate array (FPGA) devices, another Georgia Tech research team has put liquid cooling just a few hundred microns from where the transistors are operating. The new technology could allow development of denser and more powerful integrated electronic systems that would no longer require heat sinks or cooling fans on top of the integrated circuits. Working with 28-nanometer FPGA devices, the researchers demonstrated a monolithically cooled chip that can operate at temperatures more than 60 percent below those of similar air-cooled chips. In addition to enabling more processing power, the lower temperatures can mean longer device life and less current leakage. The cooling comes from simple deionized water flowing through microfluidic passages that replace the massive air-cooled heat sinks normally placed on the backs of chips. “We believe we have eliminated one of the major barriers to building high-performance systems that are more compact and energy efficient,” said Muhannad Bakir, a professor in Georgia Tech’s School of Electrical and Computer Engineering. “We believe that reliably integrating microfluidic cooling directly on the silicon will be a disruptive technology for a new generation of electronics.” Supported by the Defense Advanced Research Projects Agency (DARPA), the research is believed to be the first example of liquid cooling directly on an operating high-performance CMOS chip. To make their liquid cooling system, Bakir and graduate student Thomas Sarvey removed the heat sink and heat-spreading materials from the backs of stock Altera FPGA chips. They then etched cooling passages into the silicon, incorporating silicon cylinders approximately 100 microns in diameter to improve heat transmission into the liquid. A silicon layer was then placed over the flow passages, and ports were attached for the connection of water tubes. With a water inlet temperature of approximately 20 degrees Celsius, the liquid-cooled FPGA operated at a temperature of less than 24 degrees Celsius, compared to an air-cooled device that operated at 60 degrees Celsius. R E S E A R C H H O R I ZO N S 4 7

In a one-story brick building in Georgia Tech’s North Avenue Research Area, cooling fans in banks of computer servers whine as a large air-conditioning system blows cool air into the raised floor below them. The cooled air rises through servers and into an air return built into the ceiling. This data center simulator operates much like the massive facilities that host cloud operations for companies such as Facebook or Microsoft, as well as for innumerable smaller organizations. But as much as half of the power consumed by such data centers doesn’t go to operate computers. Instead, it’s consumed by the huge air-conditioning systems that carry off the heat generated by the computers. Depending on utility rates and other factors, annual energy bills for such facilities can total several million dollars, providing a research agenda for scientists like Joshi, who studies a broad range of data center energy issues. “Air flow management is a very important issue inside these facilities,” he noted. “We are studying how air comes up from the perforated tile floor, where it goes, and how we can change that direction. Our simulator allows us to study the critical air flow issues.” In theory, cooled air is supposed to flow up from the floor through perforated floor tiles, into the server cabinets and then up into the ceiling. Cold air is supposed to be separated from warm air, and each machine is supposed to be kept within a certain range of operating temperatures. “In reality, you get all sorts of problems with short-circuiting, in which hot air ends up in the cold aisle,” Joshi noted. “We use laser diagnostic equipment, wireless sensors, and other techniques to study how to minimize that with careful air flow control. Using that information, we’re developing techniques for improved air-flow management.” Most commercial data centers use air cooling, and big data center operators use a range of techniques to cut their energy bills, including locating facilities in cold climates such as Chicago or Buffalo, where outside air can replace air conditioning for significant parts of the year. Unfortunately, the need to provide rapid response — critical to many business applications — dictates that data centers be located close to where the data is needed, so Joshi and others are studying how to use these cooling dollars most effectively. Development of high-performance computer centers, with their growing appetite for energy, adds urgency to that effort. “I expect to see a segmented marketplace,” Joshi said. “There is going to be a large class of applications where people will just use air cooling. They may not be the most efficient from the perspective of energy use, but they will be simple. You will also see facilities designed for high-performance computing that will look very different and include liquid cooling and advanced air cooling.”

CO -DESIGN OF COMPUTING, S O F T WA R E , A N D C O O L I N G

Computer servers, system software, and cooling equipment are now designed independently and brought together in the data center. Ada Gavrilovska would like to change that. A senior research faculty member in Georgia Tech’s College of Computing and the Center for Experimental Research in Computer Systems (CERCS), Gavrilovska sees integration as the

way to control energy costs, especially as more high-performance computing systems come online and computing continues its move to the cloud. Only about 5 percent of data centers are operated by companies such as Google, which can carefully control operating conditions to boost efficiency through advanced cooling solutions or because they know their equipment and what’s being processed. Other data centers still have tremendous overhead associated with cooling. Plus, they often serve multiple clients, run many highly dynamic applications, and don’t know what’s generating heat inside the server racks. “Traditionally, on the system side, we only focused on managing the compute allocation, the storage allocation, and the provisioning of different services in the data center,” Gavrilovska said. “The primary driver was optimizing the utilization of the machines and guaranteeing performance. In many cases, there was so much focus on performance that it didn’t matter how much it cost for cooling.” On today’s commercial websites, a single click — a search for a specific product, for example — can generate hundreds or even thousands of actions. A page is displayed with a database operation, while an algorithm suggests related products, information about user interests is aggregated, and fraud detection software is launched. Modeling being done by Gavrilovska and her colleagues focuses on how thermal needs fluctuate based on operations like these, the software stack in use, the time of day, and other factors. But cooling now tends to be allocated without accounting for those factors, meaning as much as 30 percent of energy expenditures may be unnecessary. Addressing that issue will require more communication between data center operators and tenants — and better modeling. “We’ve been building a fine-grain, closed-loop system that brings in a lot of data from different levels, including the hardware, the system software stacks, and the applications,” Gavrilovska explained. “We are also building a metering capability so we can account for the overall energy implications of individual applications.” Server cooling must be allocated to prevent sporadic heavy-use “hot spots” from overheating machines, so excess cooling is often provided. System designers can help by distributing workload among servers to avoid these hot spots, and by consolidating operations where possible, allowing unused machines to be shut down. Still, Gavrilovska pointed out, there is a lot of opportunity to further close the gap through better understanding of the workload and its implication for energy use, heat generation, and cooling demand so that energy-saving decisions can lead to benefits with minimized risks. The research is supported by the National Science Foundation, the U.S. Department of Energy, and several companies with interest in data centers. With the growing demand for high-performance computing, such coordination and integration can’t come soon enough, Gavrilovska said. “The cost of energy is becoming very significant,” she said. “If we don’t change the way we are doing things, a simple loop operation on an exascale computer could require megawatts of power. Computing at this scale will very quickly become impractical.” John Toon is editor of Research Horizons magazine and director of research news at Georgia Tech.

“AIR FLOW MANAGEMENT IS A VERY IMPORTANT ISSUE INSIDE THESE FACILITIES. WE ARE STUDYING HOW AIR COMES UP FROM THE PERFORATED TILE FLOOR, WHERE IT GOES, AND HOW WE CAN CHANGE THAT DIRECTION.” In Georgia Tech’s data center simulator, researchers study air flow as part of efforts to reduce energy consumption. Cooling can account for as much as half of the energy data centers consume.

R O B F E LT

COOLING MASSIVE D AT A C E N T E R S

R E S E A R C H H O R I ZO N S 4 9

MANUFAC SUCCESS GEORGIA MEP HELPS MANUFACTURERS COMPETE AND GROW STORY BY PÃ&#x2030;RALTE C. PAUL PHOTOS BY ROB FELT

TURING

R E S E A R C H H O R I ZO N S 5 1

he challenge was clear enough for John Anker. He wanted to increase operational efficiencies in his company, AnkerPak, the manufacturing and packaging company he founded in 2004, based in Columbus, Georgia. “We’re a young company and costs are critical,” he said. Competing against other manufacturing and packaging companies, particularly from Mexico and China, adds even more pressure, he added. “We’re always looking for ways to reduce our costs, increase efficiency, and implement strategies that result in a real and meaningful monetary tangible return, and I think that’s most important to a young company, tangible returns such as cash flow.” So Anker did what most executives in his situation would do: Seek the advice of an outside consultant. The first organization he worked with was a firm based in Chicago, but it wasn’t exactly a good fit. Sharing his situation with fellow entrepreneurial CEOs in Columbus, he asked for recommendations. “I said, ‘Who have you used that showed they cared about your business and gave you a good result,’ ” Anker recounted. “Somebody in that peer group said, ‘You really ought to talk to Derek Woodham at Georgia Tech.’ ” Woodham serves West Georgia as a region manager for the Georgia Manufacturing Extension Partnership (GaMEP). A federally funded program of Georgia Tech’s Enterprise Innovation Institute, GaMEP is part of the National MEP network and is supported by the National Institute of Standards and Technology. GaMEP’s mission since it was established at Georgia Tech in 1960: To be a resource and partner available to help manufacturers across Georgia, said Karen Fite, GaMEP’s director. According to the U.S. Census Bureau, Georgia is home to about 7,300 manufacturers. “Our goal is to be able to help them grow and remain competitive,” Fite said. “For us, that means we want to meet them where they are, we want to understand what their current needs are, and we also want to help them look beyond their immediate challenge in order to think strategically not only about operational excellence, but organizational excellence.” Manufacturing is an important component of Georgia’s economy; in fact, it’s the second-largest private business industry after agribusiness. Manufacturing employs 365,000 people across the state and accounts for about 11 percent of Georgia’s $493 billion economy.

‘A GREAT RESOURCE’ Anker, the Columbus business owner, had two initial goals he hoped Woodham could help him with: One was to increase operational efficiencies and productivity in the manufacturing plant. The other was to plan the layout of AnkerPak’s separate packaging facility to maximize utilization of the space in that building. That Woodham lives in the Columbus area (all GaMEP region managers reside in the communities they serve) was a critical difference, Anker said. He saw it as reflective of a deeper commitment toward a partnership. After he laid out the operational challenges he wanted GaMEP to address, Anker said, the results were immediate. Morning meetings with senior managers at the plant changed and were structured in a way that allowed for more individual accountability and reduced the extra labor costs connected to planning and setting up on the plant floor. “It was more fluid communication,” Anker said, adding that the changes saved money — a tangible result — but they led to other benefits, as well. “The changes in morale led to better productivity. That saved us money and that money is real,” he said. “Because of that relationship we started building with the MEP, the barriers were lower and results were higher on my side. It’s a great resource to have — a great university with representatives living and working in the regions they represent.” KAREN FITE is director of the Georgia Manufacturing Extension Partnership (GaMEP) at Georgia Tech.

‘IT’S A PARTNERSHIP’ Fite, GaMEP’s director, stresses that the organization’s approach is collaborative. “The people in MEP are passionate about serving. Everyone here wants to serve manufacturers and help them grow,” she said. “When we go into companies, we’re not just going there to provide a solution, we want to create a long-term, meaningful relationship. It’s a partnership.” That’s how Scott Bunn views GaMEP’s work with his company, Groov-Pin Corp. in Newnan, Georgia. The company manufactures threaded inserts, groov-pins, and engineered fasteners and components. R E S E A R C H H O R I ZO N S 5 3

Following efficiency recommendations from GaMEP, GROOV-PIN CORP. in Newnan, Georgia, encourages employees to come up with ideas — such as this organized tools tray that is placed near each machine — to increase efficiencies.

Bunn, who is operations manager at Groov-Pin, said the company first approached GaMEP about six years ago to incorporate some lean manufacturing processes — methods designed to reduce operational waste. “They started looking at our issues internally,” Bunn said. Key areas of focus included scheduling, cutting the lead-time between orders, and shipping on time to customers. “We immediately saw results,” Bunn said. “Our on-time performance had been in the 78 to 85 percent range. Just last year, our average on-time performance was 95 percent.”

‘CHALLENGED TO EXCELLENCE’ From there, Groov-Pin tackled cutting the lead time between customers’ orders and actual shipping. The company incorporated a number of practices using the “kaizen” model, which encourages cross-functional teams within companies to continually look for areas of operational improvement and efficiency. “Our lead time was 45 days prior to implementing kaizen. After that, it was in the 20-day range. It was a significant improvement and had a big impact on sales,” Bunn said. The company also looked at creating more opportunities for staff — particularly those on the shop floor — to share their ideas. That led to regular brainstorming sessions where employees were encouraged to submit ideas to improve operations. “It was a way to empower the people on the shop floor. There’s now a microphone for them to get their ideas out,” Bunn said. Staffers now receive a $5 gift card just for submitting an idea and an additional $50 if it is implemented. The company posts all the ideas in the staff break room for visibility. “We’ve come up with some great ideas,” Bunn said. For example, one staff suggestion involved changing the tap welding process. Prior to the change, employees had to walk from their 54

workstations to another part of the plant to fuse the materials. Another employee designed a special wrench to make faster adjustments to some machines on the shop floor. “We like working with the staff from GaMEP,” Bunn said. “They challenged us. No matter what we come up with, they continually say, ‘What can we do that’s better than that?’ They would challenge our capabilities and push us to come up with the best solutions.”

SCOTT BUNN is operations manager at Groov-Pin in Newnan, Georgia.

WHERE WE ARE

The Georgia Manufacturing Extension Partnership (GaMEP), part of Georgia Tech’s Enterprise Innovation Institute, serves all of Georgia, as illustrated by this map. In 2015, GaMEP worked with 1,929 Georgia manufacturers to create or retain 2,149 jobs, save more than $25.3 million, invest $160 million back into their plants, and generate sales of more than $205 million.

‘EXACTLY WHAT I NEEDED’ Though GaMEP is primarily focused on Georgia, occasionally its efforts with in-state manufacturers lead to select projects in neighboring states. In Murphy, North Carolina, just north of the Georgia state line, Moog Components Group is part of a multinational manufacturing conglomerate that spans a number of sectors, ranging from medical devices and defense to aircraft and industrial components. Moog, which also has an engineering office in Kennesaw, Georgia, has worked with GaMEP for the past two years to improve its product development and innovation management systems. “We were working on a major product with our largest customer,” said Terry Martin, general manager of the Murphy operations. The project centered on high-performance medical motor/blowers, and to secure the order, his team needed to map out a plan to meet critical deadlines.

“The reason why I engaged with GaMEP and Georgia Tech was to help us meet this deadline,” Martin said. “If we hadn’t met the date, we wouldn’t have been awarded this large order. “I sent an email to Bob Wray, the GaMEP project manager, and he had exactly what I needed. He gave us the lean product development tools that were needed to expedite this project.” Martin said Moog scrapped its traditional method of having a project manager go to everyone involved to get updates. Instead, with GaMEP’s guidance, the team created a deliverables road map, which allowed everyone on the team to see what each member was responsible for and the areas where potential snags might occur. “Now, we had everyone in the same room, everyone could see their own little bit of the puzzle,” Martin said. “The deliverables road map is not just a rolling action item list. It’s very visual, and by looking at the timeline, you see what each person on the team has to do and how the project is supposed to move forward. They really just broke open the bottlenecks for planning the project.” With time being a critical component, the team also adopted 15-minute standup meetings, which kept members focused on the project, helped them make decisions quickly, and empowered them to take action. The changes freed up project managers to take on more responsibilities, Martin said. “We are adopting that as our standard product development project process, and we have other groups within our sector that are starting to do this as well,” he added.

‘KEEP JOBS IN THE PLANT’ As manufacturers look to GaMEP to help them create efficiencies and manage and maximize operations, the result often is overall increased productivity, Fite said. “Process improvement efforts help keep jobs in the plant,” she said. “What GaMEP does is work with manufacturers to identify and maximize their capacity. We help them cut their costs, but by doing so, they increase capacity, so that they can grow.” Indeed, the changes implemented at Groov-Pin increased productivity and efficiencies to a level where the company had to create new positions to meet growing demand. “In some areas we tackled, our productivity increased 30 to 40 percent,” Bunn said. “It’s allowed us to add some jobs, because when you do things efficiently, you improve your margins.” Those savings not only led to new jobs and equipment purchases, they allowed Groov-Pin to be competitive with others in the sector, particularly during the economic downturn. “We have been able to remain competitive by matching pricing with our domestic and off-shore competitors,” Bunn said. “That’s one of the things that sustained us during the downturn. We were able to continue based on the efficiency levels we were able to attain, which gave us a competitive advantage.” Anker, the Columbus manufacturing and packaging plant owner, said another competitive advantage of GaMEP is its structure. The fact that it is part of an internationally recognized research institution that is committed to the state is a business differentiator, he said. “I believe having it attached to Georgia Tech does make a difference,” Anker said. “That means a lot. It’s not a sales approach; the GaMEP isn’t coming to me trying to woo me. “I valued that I had someone in my community — a neighbor — with the expertise and experience in manufacturing plants to come in and say, ‘I want to help you dig deeper roots here and have more success in our state. How can we help?’ ” Péralte Paul is a business and technology writer in Georgia Tech’s Institute Communications and the Enterprise Innovation Institute. He is a former newspaper reporter. R E S E A R C H H O R I ZO N S 5 5

GLOSSARY

Nanogenerators PAGE 24, EXTREME ENERGY

Nanogenerators produce small amounts of electricity by harvesting mechanical energy from the environment. Georgia Tech researchers are working on piezoelectric generators, which harvest electricity from the movement of piezoelectric structures such as zinc oxide, and triboelectric generators, which harvest electrical charges from friction between two different materials and from electrostatic induction.

Vehicle Automation PAGE 34, ROLLING ROBOTS

Vehicle automation is measured in four levels. Level one denotes today’s driver-dependent cars; level two involves intelligent cruise and lane control with some automatic braking; level three indicates semi-autonomous vehicles that drive themselves but cede control to a human when conditions demand; and level four means fully autonomous with no driver controls.

Georgia Tech students Olivia Meek and Akanksha Menon adjust a prototype thermoelectric generator in the laboratory of Shannon Yee.

PAG E 2 4 , E X T R E M E E N E R GY

Thermoelectric Generators (thər-mō-i-ˇlek-trik)

Thermoelectric generators (TEGs) are solid-state devices that convert heat directly to electricity without moving parts. These generators are often made of inorganic semiconducting materials. Georgia Tech researchers are evaluating the use of polymers in TEGs, taking advantage of the material’s flexibility and low thermal conductivity to create TEGs that may be more efficient than conventional devices.

Microfluidic Cooling PAGE 42, COOLER RUNNINGS

Microfluidic cooling uses small quantities of a liquid, often deionized water, to remove heat from devices such as integrated circuits. The liquid is circulated using a low-power electric pump. Georgia Tech researchers are studying the use of microfluidic cooling for commercial high-performance CMOS chips and mobile devices.

GaMEP

PAGE 50, MANUFACTURING SUCCESS

The Georgia Manufacturing Extension Partnership (GaMEP) has been serving Georgia manufacturers since 1960. It offers solution-based approaches through coaching and education designed to increase top-line growth and reduce bottom-line cost. GaMEP is a program of Georgia Tech’s Enterprise Innovation Institute and is a member of the National MEP network supported by the National Institute of Standards and Technology (NIST). GaMEP has offices in 10 regions across Georgia.

FITRAH HAMID

CONNECT WITH GEORGIA TECH RESEARCH From discovery to development to deployment, Georgia Tech is leading the way and “creating the next” in scientific and technological progress. Let us introduce you to our internationally recognized experts and help you make meaningful connections with our talented students. The people listed on this page are responsive, well-connected, and ready to help you tap into everything Georgia Tech has to offer. Find out what’s new, and what’s next. Contact us today.

ONLINE RESEARCH CONTACT FORM www.research.gatech.edu/contact GENERAL INQUIRIES AND OFFICE OF THE EXECUTIVE VICE PRESIDENT FOR RESEARCH

Get all the Georgia Tech research news as it happens. Visit www.rh.gatech. edu/subscribe and sign up for emails, tweets, and more.

GAIL SPATT Program Manager Office of the Executive VP for Research 404-385-8334 spatt@gatech.edu

INDUSTRY COLLABORATION AND RESEARCH OPPORTUNITIES

CORPORATE RELATIONS AND CAMPUS ENGAGEMENT

DON MCCONNELL Vice President, Industry Collaboration 404-407-6199 donald.mcconnell@gtri.gatech.edu

CAROLINE G. WOOD Senior Director, Corporate Relations 404-894-0762 caroline.wood@dev.gatech.edu

CORE RESEARCH AREA CONTACTS BIOENGINEERING AND BIOSCIENCE

ENERGY AND SUSTAINABLE INFRASTRUCTURE

CYNTHIA L. SUNDELL Director, Life Science Industry Collaborations Parker H. Petit Institute for Bioengineering and Bioscience 770-576-0704 cynthia.sundell@ibb.gatech.edu

SUZY BRIGGS Director of Business Development Strategic Energy Institute 404-894-5210 suzy.briggs@sustain.gatech.edu

DATA ENGINEERING AND SCIENCE SRINIVAS ALURU Co-Director Data Engineering & Science Initiative 404-385-1486 aluru@cc.gatech.edu TRINA BRENNAN Senior Research Associate Institute for Information Security & Privacy 404-407-8873 trina.brennan@gtri.gatech.edu ELECTRONICS AND NANOTECHNOLOGY DEAN SUTTER Associate Director Institute for Electronics and Nanotechnology 404-894-3847 dean.sutter@ien.gatech.edu

MICHAEL CHANG Deputy Director Brook Byers Institute for Sustainable Systems 404-385-0573 chang@gatech.edu

RENEWABLE BIOPRODUCTS NORMAN MARSOLAN Director Renewable Bioproducts Institute 404-894-2082 norman.marsolan@ipst.gatech.edu PEOPLE AND TECHNOLOGY RENATA LEDANTEC Assistant Director Institute for People and Technology 404-894-4728 renata@ipat.gatech.edu

MANUFACTURING, TRADE, AND LOGISTICS

PUBLIC SERVICE, LEADERSHIP, AND POLICY

TINA GULDBERG Director, Strategic Partnerships Georgia Tech Manufacturing Institute 404-385-4950 tina.guldberg@gatech.edu

JENNIFER CLARK Director Center for Urban Innovation 404-385-7224 jennifer.clark@gatech.edu

MATERIALS

ROBOTICS

JUD READY Lead Liaison, Innovation Initiatives Institute for Materials 404-407-6036 jud.ready@gatech.edu

GARY MCMURRAY Associate Director of Industry Institute for Robotics and Intelligent Machines 404-407-8844 gary.mcmurray@gtri.gatech.edu

NATIONAL SECURITY MARTY BROADWELL Director, Business Strategy Georgia Tech Research Institute 404-407-6698 marty.broadwell@gtri.gatech.edu

R E S E A R C H H O R I ZO N S 5 7

Research News & Publications Office Georgia Institute of Technology 177 North Avenue Atlanta, Georgia 30332-0181 USA

CHANGE SERVICE REQUESTED

www.rh.gatech.edu Volume 33, Number 1 Issue 1, 2016

Nonprofit Organization U.S. Postage PAID Atlanta, GA 30332 Permit No. 587