National Academies Press: OpenBook

Extraordinary Engineering Impacts on Society: Proceedings of a Symposium (2023)

Chapter: 4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society

« Previous: 3 People Who Brought About Extraordinary Engineering Impacts on Society
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

4

NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society

The third of the symposium’s four sessions considered NSF’s Engineering Research Centers. It featured accounts of the research conducted at ERCs, discussions of the funding processes that enabled this research, and stories from women and men whose work at ERCs resulted in extraordinary engineering impacts. As session moderator Theresa Maldonado, systemwide vice president for research and innovation at the University of California’s Office of the President, pointed out, the ERC program has been a hallmark of the Directorate for Engineering and is a model of excellence for NSF as a whole. Since 1985—only four years after the launch of the Directorate—the ERCs have played a central role in producing far-reaching impacts, launched whole new industries, brought stakeholders together to achieve collective impact, developed partnerships with industry, and prepared students for lifelong careers. Furthermore, they have acted as models for other NSF center programs, including the Science and Technology Centers, Industry-University Cooperative Research Centers, Earthquake Engineering Research Centers, and Nanoscale Science and Engineering Centers.

THE ERC PROGRAM: AN OVERVIEW

Kon-Well Wang, Stephen P. Timoshenko Collegiate Professor of Mechanical Engineering at the University of Michigan, gave the lead-off presentation for the session. In his overview of the ERC program, he identified three challenges/opportunities for engineering, all of which the program is meant to address. The first is addressing the grand challenges of engineering through emerging and convergent research. “To do that, we need to build a strong core in engineering, but at the same

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

time we need to reach out and cross boundaries and absorb new emerging areas within engineering and also outside of engineering, including the natural sciences and social sciences.” This requires respecting, welcoming, and encouraging the participation of people “with different backgrounds, different training, different cultures, even different ideologies, so we can work together to tackle the grand challenges and have an impact on society.”

The second challenge, said Wang, is globalization, which entails both international competition and collaboration. “We have a smaller, flatter world, so it gives US engineers an opportunity to look beyond first-world problems and engineer for the global good and greater impact.”

The third challenge is enhancing education and workforce development, not only at the collegiate level but in preK–12 education and personalized learning and lifelong learning as well. Engineers need many skills to work in diverse and convergent environments, including leadership, communication, and teamwork skills. New technologies such as artificial intelligence and virtual learning also have shown great promise in building the future workforce.

Since its launch in 1985, based largely on guidelines proposed by the NAE (1983), the ERC program has been evolving to take on these challenges and opportunities, said Wang. Its goal has been to improve engineering research so that US engineers will be better prepared to contribute to engineering practice and to assist US industry to become more competitive in world markets. Its high-level guidelines are:

  • Promote cross-disciplinary basic research.
  • Translate research discovery to innovative products.
  • Strengthen the competitiveness of the United States.
  • Firmly link research and education and prepare the next generation of leaders.

ERCs are focused on engineering systems, with large-scale and long-term programs that span the gamut from transformative basic research to technology. A successful ERC usually receives 10 years of NSF support with the goal that the center will subsequently become self-sustaining and continue to be impactful and active in the community. Funding for those 10 years had previously been set at a maximum of $4 million per year, but in 2020 this was elevated to a maximum of $6 million per year.

Over the program’s history, there have been four generations of ERCs. Generation 1 (1985–90) aimed for interdisciplinary, transfor-

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

mational research at a single host university with industry engagement. Generation 2 (1994–2006) required the lead university to engage with multiple partner universities, develop strategic plans showing the pathway from fundamental research through enabling technologies to systems integration, increase diversity at all levels and include a minority-serving institution, and expand the educational mission and establish outreach programs to precollege educational institutions. Generation 3 (2008–17) sought to transform engineering systems, develop a globally competitive and diverse engineering workforce, and provide cross-cultural, global research and educational experience through partnerships with foreign universities and other means. And Generation 4 (2019–), which is discussed in more detail below, saw its first cohort of centers in 2020.

Over the program’s history to date, NSF has supported 79 ERCs. These programs have generated over 25,000 peer-reviewed journal publications and books; more than 800 patents, 1,300 licenses, and 2,500 invention disclosures; more than 240 spinoff companies; more than 14,400 bachelor’s, master’s, and doctoral degrees to ERC students; and many research outcomes enabling new technologies. All ERCs are required to plan their centers with three interconnected planes: a systems plane, an enabling technologies plane, and a fundamental knowledge plane.

As examples of successful ERCs, Wang cited the development of a microbial process for inexpensively producing the antimalarial drug artemisinin by the Synthetic Biology ERC (SynBERC; 2006–16), which was passed through a spinoff company from SynBERC to a major firm for scale-up and delivery to malaria-afflicted areas in Africa. Another example was the development of distributed collaborative adaptive sensing Doppler radar networks by the Collaborative Adaptive Sensing of the Atmosphere ERC (CASA; 2003–13), which has been saving lives by enabling the communication of fast and more accurate information of severe weather to help people make critical decisions.

In 2015 NSF charged the National Academies with reviewing the ERC program and developing future visions for the program. The resulting report, A New Vision for Center-Based Engineering Research (NASEM, 2017), noted that “it is important to build upon the existing strengths of the ERCs by framing them to address the biggest challenges society faces both today and in the decades to come.” Based on this report, an NSF working group developed the Generation 4 (Gen-4) ERC program with an emphasis on convergent research and

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

innovation through inclusive partnerships and workforce development. NSF also implemented a pilot planning grant opportunity to enhance convergent team formation. NSF requires the centers to demonstrate integration of the fundamental components of convergent research, workforce development, diversity and cultural of inclusion, and innovation ecosystems, in order to eventually achieve high societal impact, engaging all stakeholders, including students, faculty, staff, leadership, management, industry, innovation partners, and end users. In fiscal year 2020, NSF announced the funding of four new Gen-4 ERCs: Advancing Sustainability Through Powered Infrastructure for Roadway Electrification (ASPIRE), Advanced Technologies for Preservation of Biological Systems (ATP-Bio), Center for Quantum Networks (CQN), and Internet of Things for Precision Agriculture (IoT4Ag). For fiscal year 2022, it announced an additional four new ERCs focused on agriculture, health, manufacturing, and smart cities.1

“The ERC program is always looking for good teams of eminent scholars, as well as passionate movers and shakers, who care about making a difference in research, education, and, very importantly, societal impact,” said Wang. “This program, along with the others supported by NSF, can contribute to the community and society starting from very basic research, to technology, to how to form a team—and especially a diverse team with a culture of inclusion—to achieve great things for our society and humanity.”

BRINGING VISION TO THE BLIND

Mark Humayun, university professor of biomedical engineering and ophthalmology at the University of Southern California (USC), described the Biomimetic Microelectronic Systems (BMES) ERC. Three universities were involved—USC, the California Institute of Technology, and the University of California, Santa Cruz—and the ERC had three testbeds. The first was to create direct high-density interfaces with the human nervous system to restore lost function of sight. The second was to develop a system to restore cognitive function such as the formation of new memories. The third was initially to reanimate paralyzed limbs but later changed to create a cellular testbed to develop a photoactivated cellular

___________________

1 These are, respectively, ERCs for Advancing Sustainable and Distributed Fertilizer Production, Hybrid Autonomous Manufacturing Moving from Evolution to Revolution, Precision Microbiome Engineering, and Smart Streetscapes (NSF, 2022).

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

switch to impart light sensitivity to neurons. The center was organized along the lines of the balanced three-tier approach characteristic of ERCs (and described later in this chapter), with feedforwards and feed-backs among fundamental research, enabling technologies, and testbeds.

Humayun described the center’s efforts specifically to research and develop a biomimetic microelectronic system to restore the capacity for reading and facial recognition to the blind. “Professionally, this was very challenging and exciting for me,” he said. “And on a personal note, it was also of extreme interest to me because my grandmother, who raised me, went blind from diabetic retinopathy.”

The ERC faced many challenges, such as how to “preserve and protect these microelectronics when they were in probably the most corrosive environment that they can experience, which is the warm, saltwater environment of our human body.” To develop an artificial retina, the ERC had to devise a camera system, a way to attach it to the body, and a means of providing power to devices. In the first generation, a camera was worn in glasses to capture images. The information from the camera was sent wirelessly to an implanted integrated circuit, and this information was then transmitted via a flexible electrode array to stimulate the retina. “By having this implantable device connect to a wearable device, you jump-start an otherwise blind eye or blind retina to send information into the brain.”

A key variable, noted Humayun, is the number of electrodes inside the eye. In 2002, when the ERC grant was awarded, the number of electrodes was just 16, and they were contained in a rudimentary device that took seven or eight hours of surgery to implant. Through the ERC, the number of electrodes rose to 60, and now 240-electrode devices are being developed, “which really does start to improve the vision and the number of people we can help.”

The device developed by the ERC is the first FDA-approved implanted device to treat adults with advanced retinitis pigmentosa. Humayun showed a video of a patient with retinitis pigmentosa who was able to recognize letters projected on a screen using one of the devices and of a blind grandmother shooting baskets with her grandson. Such demonstrations “are an exciting moment for us to be able to show that this device provides not only the ability to see light and dark but much more.”

The BMES ERC has been a model of university-industry collaboration, with five outreach universities, 17 industrial partners, and the involvement of six national laboratories. Humayun listed 14 disciplines

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

that were involved, from materials engineering, including ceramics and textiles, to aerospace, aeronautical, and astronomical engineering. Eight startup companies emerged from the ERC, and it generated hundreds of patents, invention disclosures, and publications. It also developed 14 new courses and conducted outreach programs to more than 2,000 K–12 students, teachers, and families over the course of eight years.

Once NSF funding ended, the ERC transitioned into the Ginsburg Institute for Biomedical Therapeutics, which remains very active. For example, it is working on a camera that can be implanted in the eye instead of having to be worn on glasses. With federal, state, philanthropic, and commercial funding, the center and now the institute have been converting technologies into therapies and training the workforce needed to engineer and commercialize these technologies. This work could restore neural function “to potentially millions of patients for whom there’s no foreseeable cure,” said Humayun.

ENGINEERING NANO-REINFORCED POLYMER COMPOSITES IN SOUTH TEXAS

Born in Monterrey, Mexico, Karen Lozano, who is now Julia Beecherl Endowed Professor in the Mechanical Engineering Department at the University of Texas Rio Grande Valley (UTRGV), had no engineering role models growing up. Starting when she was 11, she began selling door to door dresses that her mother had made and later worked as a waitress. But when she began college at the University of Monterrey, she thought mechanical engineering would be a good major. Her mother asked if it was illegal for women to pursue engineering, but Lozano replied, “It’s not illegal, but women are just not there.” Her mother responded, “Well, how about if you pursue the path less traveled,” and, according to Lozano, “the adventures started.”

When she graduated and began looking for a job, many of the job postings announced that only men would be considered. But two professors from Rice University traveled to Monterrey to start a collaboration with her university, and they gave her an opportunity to join a research team in Houston. She earned her PhD at Rice in 1999 and then received a job offer from the University of Texas–Pan American in Edinburg, which is now the University of Texas Rio Grande Valley. Some of her professors urged her to go elsewhere because UTRGV was a teaching university at the time and she would not be able to do much research,

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

but a classmate told her, “Go to a place where you can make a difference,” so she accepted the job.

More than 90 percent of UTRGV students are Hispanic and from the local area, more than half are the first member of their family to attend college, and more than three-quarters receive financial aid. The surrounding Rio Grande Valley is 148th among the top 150 metro areas in Texas in education.

“Can I be an agent for change?” Lozano asked herself. As the first-ever female professor in the Department of Mechanical Engineering, she began writing grant proposals, despite having very little knowledge of the process, and the proposals started being funded. A Major Research Instrumentation grant from NSF enabled her to buy equipment that has attracted hundreds of students to her laboratory, which specializes in work on nano-reinforced polymer composites. An NSF CAREER award subsequently enabled her to create a “NanoTeam” that enabled research projects that prompted students to be positively engaged with their academic careers. And a Partnership for Research and Education in Materials (PREM) award permitted many more students to pursue research. Several hundred mostly Hispanic students have come through the program with 100 percent retention and graduation and a female representation that is well above national averages. The program has resulted in more than 200 peer-reviewed journal publications, 85 percent with an undergraduate coauthor, and more than 20 patents or patent applications. Furthermore, many of the students who went through the program have gone on to graduate school.

Lozano pointed out, though, that the gender gap in engineering has remained steady for about the past 30 years, with only about 20 percent of bachelor’s degrees going to women and even less in mechanical engineering. Hispanic representation in recently awarded bachelor’s degrees in engineering is low: only about 8 percent go to Hispanic men, and only about 3 percent to Hispanic women. At the master’s and PhD levels, the numbers are far worse—Hispanic representation is only about 1 percent. “There is an imperative need to further engage women and underrepresented minorities in engineering,” she said, and “the Rio Grande Valley is an area with vast potential.”

The PREM program offers a sense of belonging, holistic development, pathways to success, clarification of educational and career goals, work experiences, and the development of soft skills—“discipline, responsibility, persistence, determination, everything that a person needs to be very successful in life.” Most important, “the recipe to achieve a

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

100 percent retention and graduation rate is based on students playing active roles in research,” said Lozano. “It’s establishing that deep connection with a project and their studies and more so with a faculty member that guides and cares for their success”—a connection that persists long after graduation, since faculty members stay in touch with former students for years.

The PREM program has also created a culture of achievement, where students learn and conform to the norms and standards of the team, while discovering their potential and inner talents. They work on projects that have been strategically developed not to be too easy but also to be realistic.

Nanofibers, which are used in filtration, smart materials, tissue engineering, drug delivery, cancer diagnostics, batteries, and many other technologies, offer abundant opportunities for research and commercial applications. The standard way of making nanofibers was electrospinning, which has a very small output. But one day Lozano was eating cotton candy with her sons and realized that her students were very familiar with eating fibers made through centrifugal spinning. “We created a company and tackled the challenge of making nanofibers with centrifugal spinning, and we found a visionary entrepreneur and a great group of engineers, many recently graduated from our own center, and they were hired to design the industrial systems. This industrial system is now producing hundreds of meters of nanofibers per minute.” FibeRio Technologies Corporation, founded in 2009, drew the attention of chief executive and technology officers, technology scouts, and others, and received notable international technology awards. It was later acquired by the technology firm Parker Hannifin Corporation.

The NanoTeam also conducts large-scale outreach to K–12 students. “We want to be the pathway for underrepresented minorities for all the centers out there, [and] we need to plant seeds to recruit students to join our center, so we have to do lots of outreach.” The NanoTeam hosts summer camps, visits to schools, and even a regional science and engineering fair. More recently, through an Advancing Informal STEM Science (AISL) NSF grant, the NanoTeam obtained funding to migrate to South Texas the Energy & U/La Energía y Tu show originally developed at the University of Minnesota. Because of the COVID-19 pandemic, the show was adapted for video. It has been watched by over 20,000 young students and was awarded a Lone Star EMMY in 2022.

Since Lozano came to UTRGV, NSF has invested about $20 million in her center. She conservatively estimated that the 500 or so students

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

who have benefited from the center are collectively earning about $40 million a year. If they pay about 20 percent of their income in taxes, governments make about $8 million a year from them, far more than the grants her center has received—definitively a high return on investment. But, more important, she said, “the societal impact of our center is priceless. You cannot measure it with a number. And now we are ready to explore bigger and better opportunities to further catalyze engineering impacts on society. We have proven that we can do it.”

FROM STRUCTURES TO CITIES IN EARTHQUAKE ENGINEERING

Engineers have often had to build structures with incomplete understanding of how they will behave in an earthquake, observed Gregory Deierlein, J.A. Blume Professor at Stanford University. The 1933 Long Beach, California, earthquake did heavy damage to masonry structures, including many school buildings. The 1971 San Fernando and 1994 Northridge earthquakes revealed vulnerabilities in reinforced concrete structures, houses, and other facilities. “As engineers and scientists, we’re always learning from our experience and observations, combining that with theory and analysis,” said Deierlein. “Nowadays, that’s increasingly through large-scale computational analysis and also experimentation.”

The Pacific Earthquake Engineering Research (PEER) Center, a generation-2 ERC whose mission has been to advance performance-based earthquake engineering, approached this problem through the development of a performance-based engineering framework. The framework knits together the causes and impacts involved in an earthquake, from the intensity of ground shaking to structural responses to building damage to associated consequences such as collapse, casualties, direct financial losses, and facility downtime. In addition, the center has increasingly focused on resilience, or how communities can recover from earthquakes. It is a very multidisciplinary approach, involving earth scientists, geotechnical engineers, construction professionals, economists, and sociologists. One result, said Deierlein, is new confidence in remarkable designs, such as that of the 181 Fremont building in San Francisco, which features ductile steel braces and oil dampers to dissipate seismic energy.

This approach also has been applied to more modest structures. The 1994 Northridge earthquake demonstrated the vulnerability of many houses in California and other places where strong shaking is possible.

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

Keeping housing intact is a key factor in resilience, which is true both for new and existing houses that are vulnerable to earthquake shaking. One project undertaken at the PEER Center was the development of a technique known as seismic-based isolation, in which sliding dish insulators between a house and its foundation prevent the superstructure from being subjected to large accelerations and displacements. This technique was tested in part at the large outdoor shake table at the University of California, San Diego (discussed in chapter 3). “This was an important test to be a proof of concept to validate the design concepts and the analysis models that we were able to do.”

The center has also looked at cost-effective techniques to retrofit many older vulnerable houses, such as retrofits to foundations. It worked with the California Earthquake Authority, which regulates insurance in the state and provides funds and incentives for homeowners to retrofit their houses to make them more seismically resilient. Studies demonstrated that retrofitting was cost effective, said Deierlein, and the California Earthquake Authority has been conveying information to homeowners about how to avoid large costs by retrofitting their houses.

Recently, the center has shifted its focus from individual buildings to regions. For example, it has worked with groups at the Lawrence Liver-more National Laboratory on simulation of a magnitude 7 earthquake along the Hayward fault, which runs through the East Bay. Computer models covering almost 2 million buildings in the Bay Area showed the damage and repair costs that would occur in specific areas, which makes it possible to go beyond engineering an individual house to working with communities to engineer cities. As a specific example, the center looked at the question of how much of downtown San Francisco would be affected by damage to tall buildings that might jeopardize buildings near a still-standing but damaged skyscraper.

As a final example of the work done at the center, Deierlein noted that the world is rapidly urbanizing, with growing numbers of people moving to cities. As a result, earthquake risks will grow in the future, and “this is where we, as engineers, could start to work with urban planners, sociologists, economists, and [others], to gauge what the risk is in the future and to see what steps we could take through better building codes to retrofit policies through land use rules and so forth to help minimize the risk to future generations.”

In response to a question, he noted that multidisciplinary work speaks to the importance of remaining curious. An understanding of fields other than engineering, whether economics, art, architecture, or

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

literature, can enable an engineer to talk with others and “find commonalities with what other people are interested in,” he said. “That’s really what makes this fun. I mean, the technical part of drilling into our models is fun. But it’s the human engagement in interacting with other folks on problem solving in a very large scale that’s really fun and challenging.”

IMAGING AND THE THREE-LEVEL APPROACH

Michael Silevitch, the Robert D. Black distinguished professor in the Department of Electrical and Computer Engineering at Northeastern University, elaborated on the three-level approach that has been pioneered by the NSF ERCs and explained how it can be applied in a variety of settings. The three-level approach boils down to a set of pointed questions, he observed: So what/who cares? What are we doing this for? What is the impact of what we’re trying to do? What is the central vision? Why is it compelling? What grand challenges must be addressed? “This is a way of thinking about disruptive, integrative, transformative, and systemic technology development,” he said.

The three-level approach enables a logical development of complex initiatives. Once the system goals are identified at level 3, one seeks to identify the barriers that must be overcome. This leads to the program at level 1, which identifies the research thrusts to address those barriers. In turn, the research thrusts need to be integrated, testbeds at level 2 must be developed to validate research, and the real-world applications that emerge from the testbeds can validate the vision, leading back to level 3. Additionally, ERCs must foster an innovation ecosystem and industry involvement, motivate students, and stimulate educational programs. ERCs are thus similar to multidivision small companies, Silevitch said.

As an example, Silevitch described the NSF Gordon Center for Subsurface Sensing and Imaging Systems (Gordon-CenSSIS). The goal of the center was to develop common tools to probe hidden regions in general, with the hypothesis of “diverse problems–similar solutions,” the idea being to validate the hypothesis with testbeds in biological/cellular systems, medical imaging, underground regions, and underwater habitats. The specific (multi) sensors used to explore the regions differ but the processing algorithms and data management tools are common. Biological probes might, for example, use some combination of ultrasound and optics; breast imaging uses X-rays, ultrasound, and optics; underwater probes use sonar and infrared; and underground probes

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

use radar and acoustics. The underlying idea was to develop a unifying way of utilizing processing methods for exploring regions so that each application builds on and contributes to the others.

The testbeds, level 2, sought to validate the principle that diverse problems have similar solutions. The fundamental science, level 1, had three interlocking thrusts: subsurface sensing and modeling, physics-based signal processing and image understanding, and image and data information management. The system applications, level 3, emerging from the testbeds were built around important real-world problems: the 3D imaging of cellular structure to understand the development of a mouse egg into a healthy mouse (which, if successful, “would completely revolutionize the in vitro fertilization industry,” said Silevitch), 4D image-guided therapy of cancer tumors so that movements during treatment do not damage a healthy part of the body, 3D multimode imaging of breast cancer tumors, remote assessment of coral reefs underwater, and underground assessment of buried waste.

Silevitch went into more detail with the imaging of breast cancer tumors. The idea was to fuse several imaging modalities—impedance imaging, optical imaging, microwave imaging, and elastography—to get a much more reliable prediction of breast cancer structure. For example, data from optical imaging could be combined with X-ray data to determine how photons scatter, which then could be used to more precisely image the tumor. This can be done in near real time, which has allowed the process to become a standard approach to the treatment of breast cancer.

After NSF’s funding for CenSSIS ended, the center continued to work on the problems it had identified. Then the Department of Homeland Security announced a new competition for centers, to defeat explosive-related threats. “A tumor in the body, a bomb in a suitcase—there is no difference in terms of the tools that you can deploy. This is an example of diverse problems–similar solutions.” CenSSIS had never worked on explosive-related threats or with the Department of Homeland Security, but it won the competition. Again, the three-level approach enabled the creation of a coherent strategy of operations, with the level 3 systems goals being comprehensive defense against explosive threats and the level 1 research thrusts encompassing explosives properties, trace detection, bulk detection, and signature analysis. More recently, the Department of Homeland Security funded the center on Soft-Target Engineering to Neutralize the Threat Reality (SENTRY) at Northeastern, which has the goal of preventing or mitigating attacks on

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

soft targets like places of worship, stadiums, and schools. “Again, the three-level approach is what gave us that edge in creating a systemic, transformative, and sustainable effort,” said Silevitch.

Silevitch has also worked on applying the three-level approach in other domains. One is the goal of encouraging much broader participation in engineering, “so that when our grandchildren are in the workforce, they’re in a workforce that is diverse and representative of our country.” As part of NSF’s INCLUDES program his university proposed the Engineering PLUS (Partnerships Launching Underrepresented Students) Alliance. This $10M, 5-year effort is aimed at the goal of having an annual graduation rate of 100,000 women and underrepresented minorities at the bachelor’s level in engineering per year and 30,000 per year at the master’s and PhD levels. This level 3 vision requires working with institutional change as much as working with individual students. In turn, level 2 enables the scaling of best practices and the building of capacity, and level 1 performance strategies focus on partnerships, regional hubs, and sustainability. “The NSF three-level approach can be used to grapple with almost any major societal problem,” concluded Silevitch.

MANAGING CHRONIC DISEASES WITH WEARABLE DEVICES

The ERC for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) is a partnership among North Carolina State University (NCSU; the lead partner), Florida International University, Pennsylvania State University, and the University of Virginia, with other schools involved in strategic partnerships in areas like medicine. The vision of the center, said Veena Misra, distinguished professor in the NCSU Department of Electrical and Computer Engineering, has focused on the management of chronic disease, which is a critical problem in America. Six in 10 Americans have a chronic disease such as diabetes, heart disease, Alzheimer’s, or lung disease, and four in 10 have two or more chronic diseases. The COVID-19 pandemic made the problem even worse, with mortality rates from COVID higher for people with chronic diseases.

The center is working to develop continuous monitoring of a variety of important health parameters through self-powered wearable devices as a way of managing chronic disease. These devices would be powered by the human body itself, whether by body heat, motions, or some other

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

mechanism. The devices would have physiological, biochemical, and environmental sensors. They would be wearable, wireless, and comfortable and would generate informative and continuous data. “With all of this information combined, we wanted to explain, influence, and even predict health outcomes and gain fundamental insight into disease.”

For the ASSIST ERC, the level 2 testbeds were selected and defined based on the needs of chronic disease use cases chosen in consultation with clinicians: asthma, atrial fibrillation, diet management, wound healing, and medical detection. These testbeds drove research to overcome existing barriers. ASSIST’s engineered system consists of components that enable self-powered operations, ultra-low-power electronics that are able to function with the amount of energy that is available from the body, multimodal sensors to make the system intelligent, and antennas and radios that can relay information to a base station or smartphone using very little power.

To reduce risks and gain early wins, researchers divided the engineered system into two tracks: a sensors track and an energy track. “We wanted to get more and more energy from the body so that we could get bigger and bigger in terms of a sensing capability. At the same time, we wanted to have more and more sophisticated sensors, with the goal that at the end of our 10 years we’ve been able to combine these two tracks to build self-powered multimodal systems.” This approach has succeeded in meeting and demonstrating all the roadmap milestones mapped by the center, such as a cardiac monitoring shirt, a cardiac armband, and a self-powered biochemical platform. The center has also developed an asthma platform and a wound monitoring platform. “The only testbed that we weren’t able to demonstrate to date is one that required some fundamental understanding of what’s released in sweat when it comes to medication, and that has taken a separate route for advancement.” Many of the testbeds and wearable systems have been deployed to industrial partners and clinical labs.

As an example, Misra described a battery-free, electrocardiogram (ECG) monitoring shirt powered by body heat. The back of the shirt contains all the ultra-low-power custom electronics and sensor electronics. Textiles were used that can accommodate dry electrodes to provide both a good signal and user comfort. State-of-the-art thermal electric harvesters had to be flexible but still provide adequate power. Customized radios needed to be built to transmit real-time data on a person’s cardiac status, along with a flexible antenna that operated efficiently when placed on the human body. Super-high-energy-density capacitors

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

store the charge generated by the thermal electrics. For people who do not want to constantly wear a shirt, ASSIST has also built an armband for ECG monitoring.

Other research-enabled testbeds include some of the highest-performing thermal electrics and some of the lowest-power-consuming electronic circuits in existence, a sweat collection platform that works even without the person having to generate sweat, new enzymes for harvesting energy from human sweat, and microelectromechanical systems that can deliver power to sensors implanted in the body.

“The ERC is a great platform for bringing together multidisciplinary teams, multiple institutions, and also a pipeline of students,” said Misra. It has graduated more than 90 PhDs, generated over 650 publications, spun out 10 companies, produced 82 inventions, and received multiple awards. The connections between the center’s principal investigators have become increasingly dense even with disciplines as varied as medical sciences, the social sciences, and the humanities being involved. The center has developed a translational engineering skills program for undergraduate and graduate students, because many of the skills they need are not necessarily taught in courses. And it has generated a pipeline of K–12 students by bringing them to ERC programs at partner schools where they are exposed to challenges that allow them to build wearable devices that have particular functionalities.

Students involved with the program have been finding employment in industry and producing major impacts. One, for example, was instrumental in winning FDA clearance for the Apple Watch’s detection of irregular heart rhythms. An industry program involves companies from the entire value chain, from materials to electronic components to data and medical devices, and companies spun off from the center have been getting startup funding and are making fast progress.

Finally, Misra emphasized the program’s commitment to culture and diversity. “In our center, we have the opportunity to not only bring in individuals from underrepresented groups but to work on use cases that affect underrepresented groups.” As she noted on her final slide, “If you do not intentionally, deliberately, and proactively include, you unintentionally exclude.”

SECURING INFORMATION TECHNOLOGIES

S. Shankar Sastry, professor of electrical engineering and computer science at the University of California, Berkeley, led an NSF Science and

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

Technology Center (STC) called the Team for Research in Ubiquitous Secure Technology (TRUST), with the universities of Cornell, Carnegie Mellon, Vanderbilt, Stanford, and San Jose State as partners. He was accompanied in his presentation by TRUST executive director Larry Rohrbough.

The vision of TRUST was to radically transform the ability of organizations to design, build, and operate trustworthy information systems for cyber infrastructure. In the early 2000s, “there was a sense that we were falling behind in all aspects of cybersecurity,” Sastry said. “We realized that it was a question of [not only] new technologies but also economics, privacy policy, and law, so we thought it was important to put this together.”

The STCs were meant to be somewhat more upstream in the research process than the ERCs, but the two kinds of programs had considerable overlap, Sastry said. Both involve tight integration of research with education, outreach, and knowledge transfer to industry and to government agencies. Specifically, the TRUST approach involves research projects addressing pressing security and privacy issues of national importance, education/diversity programs to broaden participation and improve teaching and workforce development, and outreach activities to position TRUST as a leader engaging with and influencing the broader community.

The research projects had three strategic areas of focus—financial infrastructures, health infrastructures, and physical infrastructures. With financial infrastructures, a major challenge is that different systems are not in control of one organization and are rapidly evolving. One approach the center took was to focus on browsers, which now have a number of built-in protections such as password authentication systems that resulted from this work.

With healthcare infrastructures, the center took advantage of the fact that Vanderbilt University Medical Center was just launching a patient medical portal called My Health, and the central issue became how to encode privacy provisions such as those contained in the Health Insurance Portability and Accountability Act (HIPAA) into those frameworks. That required converting the legal requirements into formal specifications, which was a challenge because the legislation has contradictory mandates, Sastry observed. Various federal agencies were involved in subsequent efforts to make the laws consistent so they could be embedded in healthcare information technology.

With physical infrastructure, attention focused on the Internet of

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

Things. For example, supervisory control and data acquisition and distributed control systems help control the energy, transportation, water, and other infrastructures but also open these systems to attack. Novel sensor networking technologies for control and maintenance, secure control and intrusion resilience, and privacy-preserving demand response systems were among the center’s approaches to enhancing security.

In general, TRUST has been working to develop a science of security, which has been taken up as a priority by the National Security Agency and other federal agencies. One example is the modeling of complex interdependencies among different infrastructures, including those supporting the power, healthcare, and financial industries. Other research areas span the human-computer interface, identity theft, online tracking, data disaggregation, economic incentives, public policy levers, and technical standards. For instance, when the center started, utilities were not encoding smart meter data, and criminal groups were accessing these data, disaggregating them, and using the information to determine when a house was unoccupied and could be targeted for a break-in. “The very first thing we managed to succeed in doing is to get all these utility companies to encode the data.”

This work has generated “a huge amount of interest,” said Sastry, with many new research programs, centers, and partnerships as a result. Organizations involved have included the US Air Force, Intel Corporation, foreign governments, and various philanthropies. Other federal agencies such as the Department of Health and Human Services and the Department of Defense also have been involved in the center’s work, with research projects on security for pervasive computing, trusted computing technologies, wireless security, sensor network security, and intrusion detection and monitoring. Spinoff companies were generated and bought by larger companies, and a variety of training and education initiatives were undertaken by the center, including a summer enrichment program for early-career women faculty, new and expanded courses and other forms of curriculum development, graduate specializations in security, professional master’s and certificate programs, and summer programs for high school students and middle school girls, with a focus on broadening participation of underrepresented minorities.

“In 10 years, you can build partnerships that last a lifetime,” said Sastry. Funding from NSF was extremely useful for leveraging other forms of support, with a $40 million investment from the agency over 10 years bringing in more than $150 million from universities, industry partners, philanthropic organizations, and the federal government and

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

international agencies. The resulting long duration of funding “enables people to come in behind you and continue to invest in these programs.”

THE IMPORTANCE OF SUSTAINED FUNDING

Moderator Theresa Maldonado opened the session’s roundtable discussion by inviting comments on the value of sustained funding for the ERCs and other centers. “Ten years…gives you enough time to take your testbeds and get some data on them with your demonstration so that you can build on those partnerships,” said Misra. “You need that initial time to incubate and mature them so that you can capitalize on the investment made in those early testbeds.” As Humayun said, the overarching vision of the ERCs is to be transformative, and “it takes that much time…if you’re trying to get something going that’s truly transformative.”

Supporting students and workforce development is also a long-term investment, added Wang. “In fact, many industry partners tell us the most valuable thing they got from us as researchers is our students, because the students naturally transfer all of these technologies to industry.”

Partnerships among stakeholders become more valuable over time, observed Silevitch. “We are still working with many of the same people that we worked with in the year 2000. That’s a very powerful and cohesive force that these 10-year center-oriented programs will foster.”

Furthermore, students eventually become leaders, commented Deierlein. “I was at a meeting yesterday…where many of the speakers were students who had come through the PREM center, and now they’re leaders. By working with each other, everything amped up.” Lozano also commented on this sense of belonging to a group and a mission. “That has been very important to all of our students, feeling that they belong, that they speak that language, and that all of them are going toward the same goal through different paths—it’s very important.”

Sastry elaborated on his earlier remarks, commenting that the centers are aimed at changing societal systems, which are the slowest to change: changes in policies, laws, or attitudes take much longer than do changes in technologies or companies. Rohrbough agreed that extended funding was essential to the TRUST center’s success. “We wouldn’t have been as successful if we had three to five years to do this. We would have just been ramping up at that point.”

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

FOSTERING MULTIDISCIPLINARY WORK

In response to a question about how best to enable multidisciplinary work, Wang pointed out that one of the major challenges when working together as a convergent team is differing cultures. Changing the culture, whether for research or for furthering diversity and inclusion, can be one of the most challenging problems an ERC faces. But “that’s one thing that ERCs do well, because ERCs are long term, and many of their objectives are to advance the culture.”

Humayun recommended developing a common dictionary of terms. “We found very early on that there were two different languages being spoken.” Developing a glossary of terms and definitions and making it available to all faculty members and students made it possible for everyone to use the same words and understand their meaning.

Rohrbough pointed out that TRUST took an interdisciplinary approach from the beginning. “We brought in social scientists, we brought in policy experts, we brought in law people,” he said. “Some of the more innovative and impactful results of the center came from people who were, say, a student who was getting a joint PhD in computer science and a JD from the law school. They brought a unique perspective to addressing some of these problems.”

Lozano noted that problems look very different from the forefront regardless of the disciplinary framework one applies. “You understand fully what’s needed…. The situation brings a totally different perspective. We need more people working at the forefront to enable change in our community.”

FOSTERING PARTNERSHIPS

In response to a question about how research-intensive universities can partner with minority-serving institutions, Lozano said that the size of a grant can make a big difference. Preparation of small grants takes “a lot of precious time that you could otherwise spend working with students and mentors.” When UTRGV got its first PREM grant for $3 million for five years, she thought, “Okay, now we can do something.” Subsequent grants for comparable amounts created even more opportunities. Moreover, larger grants of longer duration permitted the formation of stronger bonds with students. “We work one on one with the students, and the students become attached to the team. After they graduate, 10 years later, 15 years later, they come back and want you to

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×

be part of their dissertation committee.” It also allows students to build longer-term relationships with industrial partners, which is particularly important to UTRGV—in part because SpaceX has been building a new development and production facility for its Starship rockets nearby.

On that note, Sastry observed that a large amount of manufacturing now takes place just south of the US-Mexico border. “This notion of having centers of excellence and engineering expertise close to the Mexican border is part of an industrial imperative…. I’ve encouraged NSF to think about US-Mexico partnerships in that lens.”

Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 43
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 44
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 45
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 46
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 47
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 48
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 49
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 50
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 51
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 52
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 53
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 54
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 55
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 56
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 57
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 58
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 59
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 60
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 61
Suggested Citation:"4 NSF Centers That Catalyzed Extraordinary Engineering Impacts on Society." National Academies of Sciences, Engineering, and Medicine. 2023. Extraordinary Engineering Impacts on Society: Proceedings of a Symposium. Washington, DC: The National Academies Press. doi: 10.17226/26847.
×
Page 62
Next: 5 NSF Processes That Fostered Extraordinary Engineering Impacts on Society »
Extraordinary Engineering Impacts on Society: Proceedings of a Symposium Get This Book
×
 Extraordinary Engineering Impacts on Society: Proceedings of a Symposium
Buy Paperback | $23.00 Buy Ebook | $18.99
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

On August 18-19, 2022, the National Academy of Engineering (NAE) held a symposium to explore how support of fundamental engineering and engineering education research by the National Science Foundation (NSF) has led to positive societal and economic impacts. The symposium - which was sponsored by the NSF Directorate for Engineering - was held to provide input to the NAE Committee on Extraordinary Engineering Impacts on Society as part of a larger effort to develop clear, compelling narratives for the public about the sources and effects of engineering innovations. Speakers at the symposium shared their personal stories and provided insights on how engineers influence not only technology and the national infrastructure but the economy, population health, manufacturing, disaster resilience, and many other aspects of daily life. This publication summarizes the presentations and discussion of the symposium.

READ FREE ONLINE

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    Switch between the Original Pages, where you can read the report as it appeared in print, and Text Pages for the web version, where you can highlight and search the text.

    « Back Next »
  6. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  7. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  8. ×

    View our suggested citation for this chapter.

    « Back Next »
  9. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!