Materials under extreme conditions

Illustration of a sample being compressed and sheared in a rotational diamond anvil cell
Illustration of a sample being compressed and sheared in a rotational diamond anvil cell

Search for new materials and phases under high pressure and large plastic shear

When you look at the properties and strength of a diamond, which is created under intense heating and pressure, it’s clear there’s value in understanding how it’s synthesized. Phase transformations under high pressure, like when graphite is formed into a diamond, are at the heart of the theoretical work Valery Levitas has been conducting throughout his extensive international career.

Levitas, Iowa State’s Schafer Professor and faculty member of aerospace engineering and of mechanical engineering, conducts fundamental research to predict and discover new phases of materials under high pressure. His work can be translated into engineering applications, including synthesizing superior materials for new technologies and products.

A significant part of his research investigates ways to retain high-pressure phases after pressure is released. To do this, he uses plastic shear, or an irreversible deformation that is applied with a rotational diamond anvil cell (DAC). He explains that plastic deformation not only changes the shape of a sample, it also changes the sample’s microstructure and generates new defects and phase transformations.

More importantly, the shear drastically decreases the pressure necessary to create desired phase transformations. “Near the defects we create, there are regions with concentrations of large stresses, which can be considered as pressures in different directions,” he says. “Instead of applying external high pressure, we apply a lower value of pressure coupled with large plastic shear to generate new defects.”

Using a rotational DAC in place of a traditional DAC has required Levitas to develop a new multiscale theory to explain the interactions between phase transformations and plastic flow under pressure. He says this is because unlike traditional high-pressure physics, which operates with the single parameter of pressure, he has to understand the effect of six components of stresses and six components of plastic strains, as well as the effect of evolving defects.

The corresponding analytical and computational approaches he developed to support his theory explain mechanisms of strain-induced phase transformations at the nanoscale as well as the complex behavior of a sample in rotational DAC.

His research group has been able to predict and confirm new phenomena through experiments. Notably, the team has proven the possibility to reduce transformation pressure by an order of magnitude to transform boron nitride from graphite-like to superhard, which may serve as a precursor of new technologies. Experiments have also revealed a new amorphous phase of silicon carbide that may shed a light on how armor ceramics are damaged under projectile penetration.

Levitas began his work in Kiev, Ukraine, and brought his high-pressure theories and technology to the U.S. in 1999. It took him eight years to obtain his first federal grant on this topic from the Defense Threat Reduction Agency, but now this work is supported by the Defense Advanced Research Projects Agency, National Science Foundation and Army Research Office.

“As the only team in the world working on this topic theoretically and the only one in the U.S. performing experiments with rotational DAC, I’m encouraged to see interest growing,” Levitas says. “Having an understanding of materials, including how they behave in natural and technological processes like earthquakes, friction and wear, surface treatment, military applications, and mechanochemical processes like ball milling, will lead to ways of controlling these processes and creating even greater materials.”

Easing traffic headaches

HallmarkInTrans performs need-based research to improve transportation infrastructure

Since Iowa State’s Institute for Transportation (InTrans) first began as the Local Transportation Information Center in 1983, researchers have transformed the surface transportation landscape through innovative methods, materials and technologies.

Now, with specialization in areas that range from work zone safety and traffic engineering to sustainable pavement and integrated earthworks operations, there are nearly 200 students, professional staff and faculty working within the 16 centers and programs that make up InTrans.

The research happening within the institute focuses on developing practical and applied solutions that can be quickly implemented to improve roadways, making the traveling experience better and safer for everyone.

Take for instance InTrans’s Center for Transportation Research and Education, which is leading three of 11 research teams under the Federal Highway Administration’s SHRP2 Implementation Assistance Program. Securing these projects involved working with three state department of transportation partners to identify priorities and pull proposals together.

The teams are working on identifying driver characteristics and roadway features that play the most significant role in road departure crashes (Iowa DOT); evaluating the roles of speed and driver distraction in work zone crashes (Minnesota DOT); and determining the effects of distracted driver behavior and speed limit enforcement on crashes (Michigan DOT in partnership with Wayne State University).

Shauna Hallmark, director of InTrans and professor of civil, construction and environmental engineering, says the ability to work with transportation agencies locally and nationally, as well as private-sector and university affiliates, has been a large part of InTrans’s success.

“We offer a unique range of expertise that is in high demand as the country addresses major issues within transportation infrastructure. These relationships help speed up improvements to roadways through knowledge sharing and thorough investigation,” she adds.

As Iowa State University’s primary resource for promoting transportation education, research and extension activities, InTrans is also improving the learning environment of students, faculty and staff.

A new Traffic Operations Lab features real-time connectivity to data and system performance directly from the field to researchers and students. “The lab extends traditional training for students and gives them an opportunity to be a part of using technology to improve systems performance and safety. The lab’s big data provides opportunities to blend transportation and computer science techniques toward developing unique front- and back-end solutions for public agencies and the transportation research community,” Hallmark adds.

InTrans is also home to Iowa State’s master of science in transportation, an interdisciplinary degree with supporting academic programs in the colleges of engineering, design and business.

Educating the next generation of transportation practitioners reaches beyond those enrolled at the university through InTrans’s GO! magazine. The online publication combined with other outreach activities help K-12 students understand the variety of career needs in the transportation industry.

“The educational component of InTrans is crucial for our institute,” Hallmark explains. “We’ve spent countless hours creating programs and activities that address everything from policy to maintenance to make the transportation system more durable, reliable, safe and sustainable. We have to prepare others to keep the momentum moving forward.”

That momentum includes more than $13.6 million research dollars secured in 2014 from federal, state and private funding. “The increase we’ve seen in high-profile projects shows that we’re a talented team of researchers dedicated to delivering results. We’re excited to continue assembling and supporting world-class teams through new projects.”

A faster way to optimal solutions

Flow streamlines in a large commercial building modeled using a turbulence model
Flow streamlines in a large commercial building modeled using a turbulence model

Using simulation and modeling to improve sustainable buildings

Insurmountable data is no match for Baskar Ganapathysubramanian. In fact, he says the more data, the better. That way he’s sure to evaluate every possible scenario within the models he creates.

Ganapathysubramanian, associate professor of mechanical engineering, uses mathematical techniques and computational tools to solve a variety of real-world phenomena.

He’s especially interested in applying this technology to energy and the environment, like he’s doing with a project that studies how energy is utilized in buildings.

He says he was initially inspired to research the topic after reading the National Academy of Engineering’s Grand Challenge to restore and improve urban infrastructure. “When I saw that approximately 45 percent of the national energy budget is used to heat and cool buildings, I knew that even the smallest improvements in energy efficiency could have a substantial impact in terms of saving costs and use of nonrenewable resources.”

Ganapathysubramanian uses modeling and simulations to investigate ways to improve design for new sustainable buildings as well as to augment existing building controls. His end goal is to improve the use of natural flows within these structures.

So far, his group has spent time understanding how beehive-shaped mud houses in Harran, Turkey, control internal temperature without any powered conditioning. Additionally, the team has looked at Iowa State University’s solar-powered Interlock House to determine the best ways to allow for natural ventilation. Another project has researchers evaluating ideal locations for air quality sensors.

“Performing this work without a computational framework requires a great deal of time and painstaking measurements to explore a select few scenarios,” he explains. “In our case, however, after we create a model of a building, we can make endless changes to our settings to determine how to make it more sustainable. The ideas we are generating, once implemented, are going to have a substantial impact on the building design and energy market.”

Creating these models is no easy task. Modeling fluid flows, such as natural ventilation, is incredibly difficult, and it often results in various levels of approximations because of the complexity of the flows.

Ganapathysubramanian says an intersection of unique developments at Iowa State supports the mathematics behind his work and has led to even better results for his research. He is also thankful for the various collaborative activities that ISU enables and supports.

Most of the building research is in collaboration with Ulrike Passe, associate professor in architecture, who is interested in leveraging mathematical models to understand and design sustainable buildings.

Collaborating with Ming-Chen Hsu, assistant professor of mechanical engineering, Ganapathysubramanian has created a framework for modeling natural flows in complex geometries. Hsu is currently looking at incorporating his immersed-modeling method that takes a complex geometry and immerses it in a cube, thus allowing the team to explore a variety of complex geometries in a straightforward way.

Umesh Vaidya, associate professor of electrical and computer engineering, helps with understanding how to control and sense the flow physics. Together with Ganapathysubramanian, they have created a rigorous framework for rapid (real-time) contaminant analysis and sensor placement strategies.

These mathematical methods and tools also have utility in other areas of energy and sustainability. Ganapathysubramanian works with ISU agronomists (like Pat Schnable and Asheesh Singh) to apply similar tools to improving agricultural productivity.

Ganapathysubramanian adds that the tools and methods are the foundation to significant improvements in science. “As we use these technologies across disciplines, we’ll see that having more time available to spend on analyzing a wide range of scenarios leads to superior end products.”

Customized products, processes

Frank Peters, interim department chair and associate professor of IMSE, in the Wind Energy Manufacturing Lab
Frank Peters, interim department chair and associate professor of IMSE, in the Wind Energy Manufacturing Lab

Delivering advanced manufacturing technology ready for commercialization

Researchers in Iowa State’s industrial and manufacturing systems engineering (IMSE) department are major players in the country’s goal to strengthen the resurgence of manufacturing in America.

With their projects to be supported by three of the recent federal manufacturing research centers – America Makes, the Institute for Advanced Composite Manufacturing Innovation and the Digital Manufacturing and Design Innovation Institute – they are working to solve unique manufacturing problems.

“Creating a product involves a great deal of reasoning and planning by individuals, which can lead to unwanted variation,” explains Matt Frank, associate professor of IMSE. “We reduce that variation through automation solutions that generate high-quality products at a competitive cost all while using fewer resources.”

But the group isn’t working in the typical factory setting. Researchers explore complex, difficult-to-make components, like wind turbine blades and one-of-a-kind replacement products.

“It’s tough to justify applying conventional automation technologies for products that aren’t high volume,” explains Frank Peters, associate professor of IMSE. “Instead, we like to partner with companies with interesting problems and create specific solutions that can be commercialized to improve the manufacturing system.”

That’s exactly what’s happening at Iowa State’s Wind Energy Manufacturing Laboratory (WEML). The lab is partnering with the National Renewable Energy Laboratory to incorporate advanced composites, specifically carbon fiber, into wind blade manufacturing. Using carbon fiber in place of fiberglass allows for lighter blades and may have the potential to lower the cost of wind energy.

Peters says WEML has been investigating composites for some time, and the connection with collaborators expedites getting the technology into industry.

In another area, researchers generate customized replacement parts – whether it’s a human bone or tractor part – with rapid manufacturing. Frank’s lab features reconfigured traditional manufacturing technologies that act like 3D printers. From there, he’s able to produce components using materials with preferred properties.

Matt Frank, associate professor of industrial and manufacturing systems engineering, in the Rapid Manufacturing and Prototyping Laboratory
Matt Frank, associate professor of industrial and manufacturing systems engineering, in the Rapid Manufacturing and Prototyping Laboratory

The group is also working on a project to connect metal 3D printers with a subtractive finishing process. “If we can implement this rapid manufacturing process in such a way that it will create extraordinarily customized products in an affordable way, it’s going to make a big impact for consumers in the United States,” Frank says.

Other projects include an automated system to produce patterns for large metal castings used in industry and military. The team has worked with the Defense Advanced Research Projects Agency to make manufacturability analysis software with the goal of reducing the design-to-build time frame. “The software analyzes proposed design ideas, giving feedback about everything from how difficult parts will be to machine, cast or weld, to what aspects within the design will drive up costs,” Peters explains. “

As the country continues to look for ways to manufacture products within a variety of fields, our engagement with industry on relevant and applied solutions are an example of how that can happen,” Frank says.

Wind characterization leads to new innovations

Expanding wind energy volume takes an interdisciplinary perspective

Hui Hu, professor of aerospace engineering
Hui Hu, professor of aerospace engineering

Aerospace engineering and atmospheric sciences are joining forces and technology at Iowa State to better understand airflow and wind shear on wind farms.

Using computer models, wind and icing tunnel experiments, and field measurements, the researchers say their work can depict individual turbine dynamics, turbine-to-turbine interaction and ultimately how wind farms impact regional wind profiles.

“The projects we’re leading give insight into how much wind energy is harvested and also the lifetime of turbines, providing an overall sense of how well a wind farm is operating,” said Hui Hu, professor of aerospace engineering. “From there, we want to figure out ways to increase efficiency, keeping cost effectiveness a priority.”

One way the team is working on improving wind farm productivity involves creating a dual-rotor wind turbine. The project, which was recently funded by the National Science Foundation, features a second rotor that fits into the larger, less aerodynamic section of the main rotor. The smaller rotor is designed to extract energy from wind that initially passes by the main rotor.

Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow
Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow

“This setup can also help in mixing out the wake, or disturbances that occur in the atmosphere from the wind turbine, replenishing the energy in the wind before it gets to the next turbine on a farm,” explained Anupam Sharma, assistant professor of aerospace engineering and Walter W. Wilson Faculty Fellow.

For this project, Hu runs experiments in the wind tunnel while Sharma develops analytical and numerical models. The combination offers a complementary environment where details can be thoroughly investigated, giving the researchers an exact picture of what would happen in the field.

But at Iowa State, the research goes one step further. Bringing in Gene Takle, professor of agronomy and geological and atmospheric sciences, the aerospace engineers can confirm their data using on-site measurements to come up with optimal solutions.

Gene Takle, professor of agronomy and geological and atmospheric sciences
Gene Takle, professor of agronomy and geological and atmospheric sciences

Takle’s research group has access to power generation data for large wind farms across the state of Iowa. And the group actively measures wind activity on different sites as well. His team looks at several factors, including wind direction, shear and speed, as well as atmospheric stability at different elevations. While his work is primarily investigating how wind turbines affect crops and soil, the information he has can be applied to the research of Hu and Sharma.

Takle says one of the most interesting things the researchers have worked on has been identifying the changes in wind flow as it goes through a large field.

“While Anupam has substantiated our observations of changing wind patterns with numerical models, we have yet to determine the implications,” Takle said. “For example, as warm, moist air is pushed up, there’s potential for it to lead to clouds and eventually rain. We want to know the larger scale impact of this phenomena and if in fact wind farms can influence weather conditions.”

As the researchers explore and expand these and other projects—like turbine blade positioning and de-icing, ideal terrain conditions and turbine alignment on farms, turbine noise signatures, and even wind forecasting—they plan to continue collaborating with one another and add insights from others on campus.

Wake simulation of dual-rotor wind turbine
Wake simulation of dual-rotor wind turbine

“The wind energy field is such that we need input from many disciplines, and the fact that we are able to bring it all together here at Iowa State makes us one of the very few places that can carry out work in such great magnitude,” Sharma said. “We’re tackling the problem the way it’s supposed to be tackled.”

Taking cyberinnovation to the farm

Ratnesh-KumarData from soil sensors gives researchers and farmers insight into sustainable agricultural practices

Maintaining soil health by protecting land suitable for growing crops continues to be a priority as the world’s population rises. Issues like managing the nitrogen cycle, which is also one of the 14 Grand Challenges identified by the National Academy of Engineering, are becoming an increasingly important part of sustainable agriculture.

Ratnesh Kumar, professor of electrical and computer engineering, says being in Iowa gave him fertile ground to expand his domain expertise beyond cyberphysical and embedded control systems (where he has earned recognition as an IEEE Fellow) and apply cyber practices to farming.

Kumar, Robert Weber, professor emeritus of electrical and computer engineering, and Ph.D. student Gunjan Pandey have developed a portable, wireless, low-cost network analyzer that can be buried beneath crop fields. The sensor measurements are intended to provide a deeper understanding of fertilizer inputs and the nitrogen cycle, both of which are a major source of water quality impairment and also result in greenhouse emissions.

The nitrogen level that has increased from things like fertilizer and certain crops that are produced, like soybeans, ought to be rebalanced, according to Kumar. He adds that plants don’t necessarily use all the fertilizer put on them, and that has been causing significant problems such as hypoxia in coastal waters. “With the data from our sensors, we want to be able to determine the adequate amounts of fertilizer to apply as well as uncover ways to improve irrigation practices.”

The sensors Kumar and his team have designed collect information about water levels and soil nutrients, gathering details at a wide range of frequencies through measurements of complex impedance. This detail includes capacitance (how an electrical charge is stored) affected by moisture and conductance (how easily an electric current passes) affected by nutrients present in their ionic forms.

A key feature to the sensors is a first-of-its-kind wireless interface. Kumar says such an interface allows the sensors to be used in-situ, so researchers can actively gather information without interfering in any agricultural operations. The design was inspired from “meta-materials” that feature electromagnetic properties not found in natural materials.

“The sensors also have an inbuilt calibration mechanism so they don’t need to be manually calibrated each time conditions, such as temperature, change,” he added.

The group is also working with agronomists, specifically soil scientists and crop scientists, to develop sensor-driven models for soil- and crop-growth dynamics. Kumar says such understanding is crucial to the management of soil nitrogen and other nutrients as well as soil health.

His research has been supported by the National Science Foundation through two prior grants and was recently awarded a $1 million, four-year grant from NSF under the CyberSEES program. Additionally, the sensors component has one pending U.S. Patent.

Kumar says he has even more advancements in his sights. “Going forward, we will be thinking about the entire system of soil, plant and air. They all must be monitored simultaneously to assess the soil, plant and air attributes relevant for soil, water and air health toward sustainable agriculture.” Electronic microchips send frequencies out in the ground to detect movement amongst other things.

Shifting the paradigm of biorenewable chemicals

shanksCBiRC focuses on platform technologies and new chemicals from biomass feedstocks to replace petrochemicals

When the National Science Foundation Engineering Research Center for Biorenewable Chemicals (CBiRC) was founded in 2008, its approach of combining biology and chemistry to develop sustainable biobased chemicals was a novel idea.

“At the time, we were trying decide if there was value in having people from the biological area—those who work in enzymes, proteins and microbial systems—in the same center with classical chemical conversion researchers,” explained CBiRC’s director Brent Shanks.

Six years later, it seems the partnership was indeed a good strategy.

CBiRC has more than 25 faculty researchers, numerous graduate students and 35 industry partners focused on changing the chemical industry.

One of the biggest challenges to CBiRC’s mission is that there are hundreds of products made from petroleum-based chemicals.

“A lot of organizations working on biorenewable chemicals will focus on one or two products, but it’s hard to justify the cost and time it takes to develop such a small number of products when you are dealing with a market that is so diverse,” explained Shanks, who is also Iowa State’s Mike and Jean Steffenson Professor of Chemical and Biological Engineering. “We are striving to break away from that lone end-product mindset.”

Instead, CBiRC wants to develop a platform technology—one that can be developed and then simply exploited to make a range of different products.

Shanks says novel biological intermediates give CBiRC the opportunity to make this technology a reality.

“We are using biological conversions to get to unique intermediate molecules. From there, we use chemical conversion to go to a range of different chemical products, essentially creating a star diagram, where an intermediate molecule from fermentation can make a whole range of different molecules,” he added.

One such intermediate molecule is triacetic acid lactone, which can be created through biological conversion and converted to a variety of products. An example end product created by CBiRC researchers from this platform is pogostone—an antimicrobial that has a great deal of potential but has been difficult to synthesize in the past. By starting with triacetic acid lactone, pogostone was developed in one step.

While CBiRC’s approach seems subtly different, it’s incredibly important. That one intermediate molecule can lead to solutions for high-value, specialty products as well as large-volume, low-value commodity products.

“With our technologies, we can get to families of molecules that people generally haven’t ever considered and start to examine the efficacies of these molecules to come up with some interesting options,” Shanks said.

As CBiRC researchers publish their work and get patents on technologies, the center is inspiring spin-off companies to help to move the technology forward.

There are currently six start-up companies working on a range of biorenewable chemical products. One example is Glucan Biorenewables, which is exploring how to best make organic furanic compounds such as furfural. And the other companies have similar missions—making a promising product available and accessible.

“There’s evidence this platform-technology approach will work, giving the biorenewable chemical industry a foundation for building many products. It’s exciting to consider just how much of an impact this could make,” Shanks said. CBiRC researchers develop novel biocatalysts in the interdisciplinary Biorenewables Research Laboratory.

Changing cancer treatment

lab work
Katie Bratlie (right), assistant professor of materials science and engineering and chemical and biological engineering and Rachel Philph, senior in materials science and engineering and Goldwater Scholar work together in Bratlie’s lab.

Polymer science advances drug-delivery mechanisms to better break down cancerous tumors

The National Cancer Institute has indicated that in 2014, “it is estimated that there will be 1,665,540 new cases of all cancer sites and an estimated 585,720 people will die of this disease.”

That’s why Katie Bratlie, an assistant professor of materials science and engineering and chemical and biological engineering at Iowa State University, wants to create a more effective and efficient way to treat the disease. And so she is developing biodegradable polymers to improve chemoimmunotherapy—a type of chemotherapy that works with the immune cells to remove cancerous cells.

The immune cells she’s working with are white blood cells called macrophages. Found all across the human body, macrophages are considered the “first responders” to bodily injuries, removing bacteria and debris.

Despite being good for the rest of the body, macrophages in tumors make the prognosis for cancer patients much worse. That’s because these cells promote blood vessel growth, bringing nutrients to the tumor and helping it grow.

macrophage
White blood cells called macrophages are considered “first responders” to bodily injuries, removing bacteria and debris

“Once those blood vessels are established, the tumor cells have a place to metastasize across the body,” explained Bratlie. Macrophages offer an advantage in that they take up drugs relatively easily, making them a great resource for Bratlie, who is determined to find a way to utilize the proprieties of tumor-associated macrophages for treating cancer.

She and her team are looking at a variety of chemical characteristic groups to uncover a functional group that will alter macrophage secretion profiles, essentially reprogramming the macrophage cells to act in a pro-inflammatory capacity, fighting off the tumor rather than promoting its growth.

When she finds the ideal polymer, she plans to integrate it into a hydrogel that will encapsulate a cancer-treating drug. Her technique would allow the medicine to be delivered directly to a growing tumor without impacting surrounding cells.

“Using this approach, the drugs used to treat a cancer will attach to a malignant cell and signal to macrophages and other white blood cells that the cancerous cells should be phagocytosed, or digested,” she explained.

As the team is analyzing cells and studying their responses to polymers in petri dishes in the lab, it is looking for apoptosis, or cell death, to ensure the treatment is effective in killing cancerous cells. The group is also conducting animal trials and collaborating with researchers who have expertise in animals and humans to explain tumors and physiology.

The ultimate dream, while likely many years down the road, is to bring the research to clinical trial. Bratlie says some day it may also be possible to personalize the macrophage response based on cancer stage and other factors, making for a more individualized approach to this combination cancer therapy.

Her research is also applicable in other areas, as macrophages are being studied across Iowa State’s campus, including their role in vaccines and parasitic diseases.

“Some diseases, like tuberculosis, actually reside inside the macrophage, so it doesn’t get destroyed. Instead it divides and stays. It’s a persistent infection,” she said. “If we could do something inside the microphage to remove the infection or attack it, that would be a great advancement.” Katie Bratlie (right), assistant professor of materials science and engineering and chemical and biological engineering, and Rachel Philiph, senior in materials science engineering and Goldwater Scholar, work together in Bratlie’s lab. White blood cells called macrophages are considered “first responders” to bodily injuries, removing bacteria and debris.

A new kind of solar cell

vik-dalalImproving the performance of organic, thin-film materials with perovskites to make solar energy more affordable and accessible

With the sun providing most forms of energy, whether indirectly or directly, it’s no wonder Vikram Dalal has spent more than 40 years working on better ways to access its energy.

But it’s the potential to provide the developing world with a more reliable source of energy that most inspires him.

Dalal, Whitney Professor of Electrical and Computer Engineering, says cost-effective solar energy could be a consistent source of electricity for parts to the world that typically rely on diesel generators or kerosene for energy.

“If we could accomplish this, it would mean clean drinking water, refrigeration to keep vaccines cold and electricity at night. All positive things that could drastically improve people’s way of life.”

And so, Dalal is working on a new class of solar cell. His research, which is currently funded by the National Science Foundation as well as the Iowa Energy Center, joins organic and perovskite solar cells with thin films of silicon.

Perovskites are a new system of materials that are increasingly efficient at converting solar energy into electricity. When perovskites are combined with thin-film silicon cells, which use amorphous silicon that is only a few hundred nanometers (a billionth of a meter) thick, or organic solar cells that are applied to a semi-transparent panel to absorb sunlight, there is potential for these cells to convert 20 percent of the light they absorb into electric energy.

That would match the efficiency of conventional solar panels, something that has yet to be done with newer technology. In addition, these cells would be more cost-effective, requiring less expensive material than the silicon crystals currently in use.

A major problem facing both organic and perovskite cells is that they degrade rapidly in performance due to environmental factors such as moisture and light exposure. Not much is known about the fundamental physics of why these cells degrade, so Dalal’s research is working to understand these phenomena. Over time, he will then design new materials and device structures that are much more stable with the goal of reaching a 20-year life for these cells.

“We have many challenges to overcome, both in improving efficiency and achieving much better stability. That’s why we’ve begun working with several disciplines, including chemistry and physics, and we are forming new partnerships, like that with Nazarbayev University, a new university in Kazakhstan’s capital city of Astana,” he says. Dalal adds that bringing together experts in organic and perovskite solar cell research will help advance the technology.

“Making solar energy better and cheaper will allow solar to penetrate the large-scale utility market as well as be widely utilized in developing countries. It’s something I’ve been working on for a long time, and these new cells could be the solution.”

Advancing production in large-scale industries

Calling for a multidisciplinary, value-driven philosophy for systems engineering

Energy. Transportation. Civil infrastructure. Aerospace. These and many other large-scale, complex industries are critical to the security and prosperity of our nation. And they are in need of some serious attention.

That’s where Christina Bloebaum says she can make a difference. Bloebaum, the Dennis and Rebecca Muilenburg Professor of Aerospace Engineering at Iowa State, is investigating a new educational and technological framework to improve the way these systems and related products are developed.

Christina BloebaumThe implication of her work is a more efficient use of valuable resources, like time and money, while making an end product better suited for specific purposes.

Her approach, which uses integrated research in social sciences and engineering, emphasizes a value-driven design process. This requires each decision to be tied back to a value function, such as maximizing profit or mission success, which is established at the beginning of a project.

“We also want to explore the use of serious games to enable research as well as educate the future workforce about how these complex products and systems are designed and delivered,” she adds. “Gamification offers an immensely powerful yet largely unexplored approach to enable a paradigm shift in practice, as well as training, in systems engineering.”

As the former NSF program director of both the engineering and systems design program and the system science program, Bloebaum has seen a need for this sort of research firsthand, noting the current approaches used aren’t keeping pace with technological advancements.

Her own accounts are supported by the National Academies’ Rising Above the Gathering Storm, Revisited report, which describes how America is falling behind on the technology front and suggests that drastic measures need to be taken.

Bloebaum knows a change in systems engineering at the highest of levels involves a lot of different ideas coming together. Her experience with informed decision support through work on multidisciplinary design optimization will prove useful. And she’s gathering other ideas through interdisciplinary research teams coordinated to pursue grants related to her overarching idea.

“There are so many different components that need to be addressed in what we are proposing to do—from what type of widget to use to how communication flows through organizations—and we need to analyze a great deal of information to determine what changes can have the biggest impact,” she says.

Visualization technology will help support the process. She has used the technology to capture decisions made by end users of a complex product as well as to provide a representation of how the systems engineering process flows, identifying how changes in one area affect other areas.

Because her framework will mean altering long-standing processes, Bloebaum wants to provide demonstrations of success by partnering with larger agencies, such as NASA.

“Once we can prove we have a low-risk, incredibly high pay-off proposition, we can show others the benefits of our approach,” she says. “Along the way, students will have learned this framework through our educational outreach, and the result is a self-sustaining solution to a serious problem.”

Revolutionizing disease prevention and treatment

balajiUsing a systems approach coupled with nanoscale technology to develop next-generation vaccines

For more than a decade, Balaji Narasimhan has been determined to improve vaccine deliveryand availability, a mission that’s especially important for parts of the world where access to such life-saving, preventative medicine isn’t always practical or even possible.

One project includes searching for ways to boost the effectiveness of vaccines through experiments with the chemical composition and size of polymer-based nano particle adjuvants used to deliver antigens that trigger the body’s immune response, tailoring these to be released over an extended period of time. Another looks at using nanoparticles to load vaccine components and delivering them “needle free” to improve patient compliance.

Now, Narasimhan, Vlasta Klima Balloun Professor of Chemical and Biological Engineering, is leading a collaborative effort in vaccine development with 43 investigators from five universities, two national labs, three research institutes and five companies. The group will be seeking large-scale funding to launch a national center on nanoscale technologies to develop next-generation vaccines.

The project, entitled “Systems Design of Nanovaccines,” will receive up to $1.5 million over three years as part of Iowa State’s Presidential Initiative for Interdisciplinary Research, a program launched by President Steven Leath to support research efforts that could lead to major advances, discoveries and technologies.

The research group plans to use a systems approach for vaccine development. Different from the current step-by-step method, the systems perspective frames the development of new and improved vaccines as a supply chain and considers all the steps—ranging from conceptualization to testing to global distribution and everything in between—as early as possible with built-in feedback at each step.

“The result is a better product made in a shorter period of time because you don’t have to wait for one step to be done to start the next. It could potentially shorten the time it takes to develop new vaccines from 10 years to about 5 years,” Narasimhan says.

Building on his existing research in nanotechnology, Narasimhan adds that formulating the vaccines into nanosized particles is effective because the immune cells the vaccines are trying to activate typically do a good job of internalizing, or taking up, the smaller particles.

Many viruses, such as H1N1 influenza and SARS, are also nanosized. “We are trying to mimic some of those pathogens using synthetic, man-made degradable polymer particles containing proteins specific to the pathogen to essentially trick the immune system into thinking it’s dealing with those pathogens so it mounts a potent immune response,” Narasimhan explains.

In the end, Narasimhan hopes the group’s efforts make vaccines more accessible. That might mean single-dose vaccines that can be self-administered. Or it could be vaccines that don’t have to be refrigerated, which would cut costs in half. Or maybe it’s a combination of those things and more.

“For these sorts of advancements to be made, we really need to operate in a cross-disciplinary setting,” Narasimhan says. “We need to be open to embracing ideas from other fields, as collaborating with experts gives us an advantage to develop better vaccines and with more efficiency.”

Reducing the cost of wind energy

laflammeSensing skin monitors structural health of wind turbine blades, giving insight into needed repairs

An inexpensive polymer that can detect damage on large-scale surfaces could be pivotal in making wind energy a more affordable alternative energy option.

The material, which is made into 3-inch square pieces, is a nanocomposite elastomeric capacitor fabricated from a dielectric layer sandwiched between two painted conductive layers. When the skin is placed on a surface, engineers can measure its capacitance, or stored electrical charge, to make inferences about any changes in geometry taking place on that surface.

Simon Laflamme says using this material on large-scale structures, such as wind turbines, could mean making less expensive, condition-based repairs when small cracks and other deformities appear instead of incurring the high cost of maintenance on a fixed time interval or after a breakdown, which may necessitate the replacement of huge components, like an entire turbine blade.

Laflamme, assistant professor of civil, construction and environmental engineering, has been developing the sensing skin since he was a student at MIT. While he didn’t originally plan on the skin being used on wind turbines, he says it’s a great application.

That’s because current structural health monitoring of wind turbine blades can’t be done in real-time on a continuous basis. “The turbines have to be physically inspected, and this usually happens only once or twice a year. By the time inspectors get to a blade, it could have sustained too much significant damage to do minor repairs,” Laflamme explains.

Once it’s adhered to a surface, the sensing skin would act as an indicator, automatically telling engineers to inspect a blade if something unusual happens. Over time, a pattern of how blades deteriorate emerges, providing insight into better maintenance plans for wind turbines, which could extend the life of the blades, as well as provide new ideas for future blade designs.

All of these factors come together in what is called an automated condition assessment. “The sensing skin is integral in capturing the entire lifecycle of blades as changes happen rather than through the reverse inspection that is used today,” Laflamme adds.

His research has become truly multidisciplinary. The skin itself is produced in collaboration with the materials science and engineering department, but it also has ties with electrical and computer engineering for designing cost-effective data acquisition systems. Additionally, various efforts have been undertaken with aerospace engineering and several centers on Iowa State’s Campus, including the Center for Nondestructive Evaluation and the Bridge Engineering Center.

Laflamme says an approach that brings in different ideas is absolutely necessary. “It’s the way modern problems are going to have to be solved. We have to share insight to create the best solution,” he explains.

He adds that he appreciates being able to bring this perspective to the undergraduate and graduate students working on the research project. “We have at least 12 students who are getting a sense of how valuable multidisciplinary engineering is, and they are truly enjoying the experience,” Laflamme says. “Integrating the concept into their education means it becomes a natural way of thinking for the next wave of engineers in industry, and that’s going
to mean big things for what’s to come.”

A smarter power grid

Manimaran GovindarasuCyber-physical testbed gives realistic platform for power grid security research

With the nation’s security and economic vitality in his sights, Manimaran Govindarasu is setting out to make the power grid infrastructure more resilient against evolving and continuous cyberattacks.

These attacks could result in anything from compromised data within utility companies to significant blackouts across the country.

“Our current power grid is designed to manage randomly occurring faults from things like devastating storms, but it doesn’t have the same capacity when it comes to malicious cyberattacks,” explains Govindarasu, Mehl Professor of Electrical and Computer Engineering.

Competing with these attacks and developing defensive and mitigative strategies requires a safe, realistic place to configure and simulate compromises to the grid. That environment is exactly what Govindarasu is creating with a cyber-physical security testbed.

The testbed, which integrates industry standard control software, communication protocols, and field devices combined with real-time power system simulators, provides an accurate representation of cyber-physical grid interdependencies.

Researchers, including faculty and graduate and undergraduate students, use the testbed to assess vulnerabilities and risks, analyze system impacts, and validate and evaluate countermeasures.

Govindarasu also incorporates the testbed into the coursework of a senior/graduate-level course on cybersecurity as well as in senior capstone design projects. Additionally, he offers the technology to outreach programs, giving people outside the university a chance for hands-on experience with power grid and cybersecurity.

“Not only are we studying the impact of these attacks, we are gaining insight into how to prevent them from happening in the first place,” Govindarasu says. “It’s a great opportunity for all those involved—the students get to learn technical skills, and their projects provide more data to incorporate into our research.”

The system he has created is unique on a university campus, but Govindarasu feels it’s the best place for such a technology.

“We are uniquely positioned at Iowa State because we have strong industry-university collaborative programs in information assurance and power engineering. Taken together, we can incorporate all these ideas in one place and really start doing something about the problem,” he says.

While the testbed is operational, Govindarasu is working on enhancing it by scaling it up, federating it with complementary testbeds and adding remote access capability. These advancements require creative solutions, but they would also allow for more partnerships to form within the project.

“Other universities and national labs want to be able to access the testbed to run different scenarios and collect results. We want to create a web interface that would allow for this work and also add to the functionality of the technology,” he says.

The testbed was first funded by a strategic research initiative within the electrical and computer engineering department. Later, the college added funds when the project showed promise. Now, it has support from the U.S. National Science Foundation and in-kind donations.

“It has taken some time to develop a full system that functions so well, and it has been a synergistic group effort with my colleagues Dr. Ajjarapu and Dr. Jacobson and our students,” Govindarasu says. “We definitely have more work and collaborating to do, but it’s exciting to be part of something that is so timely and can have such an important impact.”

Study results from Iowa State University broaden understanding of control engineering

Current study results on Control Engineering have been published.

News originating from Ames, Iowa, by VerticalNews correspondents, says the research paper, “presents a methodology, motivated by aerospace applications, to use second-order cone programming to solve non convex optimal control problems. The non convexity arises from the presence of concave state inequality constraints and nonlinear terminal equality constraints.”

The paper concluded, “Applications in highly constrained spacecraft rendezvous and proximity operations, finite-thrust orbital transfers, and optimal launch ascent are provided to demonstrate the effectiveness of the methodology.”

 

Levitas uses basic statics principles to solve long-standing problem in interface science formulated by Gibbs

Levitas-Web-Version
Valery Levitas

Valery Levitas, Schafer Professor and faculty member of aerospace engineering and mechanical engineering, found a strict and simple solution to the classical problem in the interface and surface science formulated by J. W. Gibbs in the 19th century. Namely, he uncovered a way to define the position of a dividing surface.

The Gibbsian view of a dividing surface, or sharp interface, is a mathematically constructed thin layer between two phases. Not knowing the position of a dividing surface creates numerous problems when defining properties of nonequilibrium interfaces, in particular, interface energy and stresses.

For more than a century, there was no defined way to determine the dividing surface. Surprisingly, Levitas uncovered the solution from a completely different discipline – statics, and more specifically, the principle of static equivalence (Levitas V.I., Physical Review B, 2014, DOI: 10.1103/PhysRevB.00.004100).

Combining his expertise in phase transformation research with this statics principle, Levitas determined that the dividing surface is statically equivalent to a nonequilibrium finite-width interface with distributed tensile stresses if it has (a) the same resultant force equal to interface energy and (b) the same moment, which reaches zero (or equal to zero) about dividing surface.

Ironically, even if these two conditions were found, they may be potentially inconsistent with each other. So, Levitas utilized some new results within the phase field approach and a corresponding analytical treatment to demonstrate that these conditions are actually consistent.

The results of his study are applicable to all types of interfaces, including those between different phases in multiphase and composite materials, grain and twin boundaries, and external surfaces.

“If I did not teach undergraduate statics, I would not have formulated this interface science problem as a simple statics problem and would not have solved it,” said Levitas. “While it only took a few hours to solve the problem, it took more than a century to formulate it in such a way that it could be solved.”

Levitas plans to include this problem in his statics class, continuing his trend of incorporating nontraditional problems, like high-pressure physics, reaction of nanoparticles, and material synthesis under high pressure and shear problems, in the course. He says these concepts are important to show students because they demonstrate a broad application of statics in science and engineering.

March 26, 2014 by Jessi Strawn

Iowa State, Italy Researchers Collaborate on Structural Health Monitoring

Iowa State researchers meet with University of Perugia (Italy) researchers in Italy, summer 2013.
Iowa State researchers meet with University of Perugia (Italy) researchers in Italy, summer 2013.

Two cultures collaborate to develop novel structural detection methods.

Researchers from Iowa State University and University of Perugia (Italy) compare U.S. patented soft elastomeric surface sensors with Italian cement-based embeddable sensors. Both of these technologies are being developed as novel nanocomposite solutions to dynamic structural monitoring. The goal is to provide cost-effective solutions for locally monitoring large-scale structures.

“We are contributing ideas to each other’s projects to make both technologies work,” said Simon Laflamme, assistant professor of civil, construction and environmental engineering (CCEE) at Iowa State.

The Iowa State researchers include Laflamme, CCEE Associate Professor Halil Ceylan, and structural engineering doctoral student Hussam Saleem. Researchers from the University of Perugia include Associate Professor Gianluca Cerni, doctoral student Alessandro Corradini, postdoctoral research associate Antonella D’Alessandro, laboratory technician Massimo Mancinelli, Professor Annibale Luigi Materazzi, Assistant Professor Filippo Ubertini, and Assistant Professor Luca Valentini.

Ubertini is the main Italy contact on this project. He has been a faculty member in University of Perugia’s civil engineering course (U.S. equivalent to “program”) since 2008, where he currently teaches bridge design and theory.

Their work has been summarized in a journal article, “Novel Nanocomposite Technologies for Dynamic Monitoring of Structures: a Comparison between Embedded and Surface Sensors,” published in March 2014 in Smart Materials and Structures. Further journal papers, a graduate student exchange, and other activities will be formed from this partnership.

The partnership also allowed CCEE graduate student Hussam Saleem to meet and conduct research with students from a foreign university. “I broadened my perspective on research to an international level, rather than what can only be accomplished in the U.S.,” Saleem said. He also enjoyed the cultural tours; his favorites being the historically preserved Assisi, Italy, and of course, the best pizza he’s ever eaten. “The pizza there tasted better than anything I ever had.” In addition to Iowa State, the Jordan native also has researched at University of Strathclyde in Glasgow, U.K.

The Iowa State University-University of Perugia collaboration received funding from the Iowa State University International Grants Program for 2013. The ISU Council on International Programs, based out of the Senior Vice President and Provost’s Office, sponsored the grants program. The goal is to emphasize global learning, discovery and engagement as outlined in the university’s strategic plan.

March 6, 2014 by Chris Neary

Iowa State’s Icing Wind Tunnel Blows Cold and Hard to Study Ice on Wings, Turbine Blades

Iowa State's Hui Hu examines ice on a test model taken from the university's Icing Research Tunnel.  The refurbished tunnel, which has been fully functional for a few weeks, is in the background.  Photo by Bob Elbert.
Iowa State’s Hui Hu examines ice on a test model taken from the university’s Icing Research Tunnel. The refurbished tunnel, which has been fully functional for a few weeks, is in the background. Photo by Bob Elbert.

From somewhere back behind the Iowa State University Icing Research Tunnel, Rye Waldman called out to see if Hui Hu was ready for a spray of cold water.

The wind tunnel was down to 10 degrees Fahrenheit. A cylindrical model was in place inside the 10-inch-by-10-inch test section. The wind was blowing through the machine at 60 mph. So yes, said Hu, an Iowa State professor of aerospace engineering, turn on the water.

Waldman, a post-doctoral research associate, hit the controls and three spray nozzles threw a fine mist up into the wind. The tiny water droplets circulated through the tunnel, hit the model and started freezing. Within minutes, the frozen droplets distorted the model’s smooth and regular shape.

That ice is the result of a three-year project to fully refurbish a 20-year-old icing wind tunnel donated to Iowa State by the Goodrich Corp. (now UTC Aerospace Systems). The wind tunnel can operate at minus 20 degrees Fahrenheit with wind speeds as high as 220 mph. It can create everything from frozen fog to wet glaze ice. It has been fully functional for a few weeks.

“We’re trying to understand how the ice builds up on aircraft wings and wind turbine blades,” Hu said. “We want to understand the underlying physics. And when we understand the physics, we can develop better models to simulate and predict when and how ice will build up on cold days.”

Ice can build up “to quite ugly things” that are dangerous and costly, Hu said.

Ice changes the geometry and balance of wings and blades. That can rob aircraft wings of lift and cause crashes. It can reduce the efficiency of wind turbine blades tremendously, cutting the power harvest from winter’s strong winds. It can also throw off the balance of a wind turbine’s spinning blades, putting tremendous forces on shafts and machinery, leading to failures or shut-downs. Thawing ice on turbine blades can also be thrown hundreds of yards, potentially hitting people, buildings or vehicles.

With a better understanding of the icing problems, Hu said engineers could develop better solutions.

Hu said there are only a few icing wind tunnels in the country, and the ISU Icing Research Tunnel is the only one on a university campus.

Rye Waldman, Hui Hu, and Kai Zhang, left to right, work with the Iowa State University Icing Research Tunnel.  Photo by Bob Elbert.
Rye Waldman, Hui Hu, and Kai Zhang, left to right, work with the Iowa State University Icing Research Tunnel. Photo by Bob Elbert.

Hu will use the tunnel as part of a $663,000 grant from NASA to study icing of aircraft wings, part of a $360,000 grant from the National Science Foundation to study icing of wind turbine blades and part of a $20,000 seed grant from Iowa State’s Institute for Physical Research and Technology to develop new technology to study aircraft icing. He’s working on the projects with Alric Rothmayer, an Iowa State professor of aerospace engineering; Kai Zhang, a doctoral student; and Waldman.

They’re using cameras and lasers to take advanced flow measurements, including particle image velocimetry, molecular tagging thermometry and digital image projection.

“In the past, there haven’t been many quantitative experiments to let people see the underlying physics of wing and turbine blade icing,” Hu said. “This is what’s really needed.”

Hu’s experiments, for example, show everything from the thickness of ice as it flows over a wing, the heat transfer of individual water droplets as they freeze, the irregular speed of freezing droplets on a wing or blade and the finger-like patterns of ice formation.

Though they share similar airfoil shapes, Hu said icing on aircraft wings and wind turbine blades can be quite different.

That’s because wings are typically made of metal, have very smooth surfaces and are good heat conductors. Turbine blades are typically a composite such as fiberglass, have rougher surfaces and don’t conduct heat very well. Wings also operate under drier conditions when they’re at altitude; turbine blades near the surface are in the middle of winter sleet and snow.

“All of that makes a huge difference,” Hu said.

So far, most of the data about airfoil icing is related to aircraft.

“But the anti-icing strategies that work for aircraft might not be best for a wind turbine,” he said.

Now that Iowa State’s icing wind tunnel is up and running and looking brand new, Hu said Iowa State engineers will be gathering more and more data about all kinds of icing issues.

February 11, 2014 by Mike Krapfl

Iowa State Engineers Upgrade Pilot Plant for Better Studies of Advanced Biofuels

Marty Haverly, top left, and Lysle Whitmer, bottom right, inspect recent upgrades to Iowa State University's pilot-scale fast pyrolysis equipment. - Photo by Bob Mills of the Bioeconomy Institute
Marty Haverly, top left, and Lysle Whitmer, bottom right, inspect recent upgrades to Iowa State University’s pilot-scale fast pyrolysis equipment. – Photo by Bob Mills of the Bioeconomy Institute

Lysle Whitmer, giving a quick tour of the technical upgrades to an Iowa State University biofuels pilot plant, pointed to a long series of stainless steel pipes and cylinders. They’re called cyclones, condensers and precipitators, he said, and there’s an art to getting them to work together.

The machinery is all about quickly heating biomass (including corn stalks, switchgrass or wood chips) without oxygen to produce solid biochar and liquid bio-oil. The former can fertilize crops; the latter can power the economy.

The process is called fast pyrolysis. It’s a thermochemical way to break down plants for the production of advanced biofuels. Whitmer, the senior research engineer for Iowa State’s Bioeconomy Institute, and other Iowa State engineers have been studying the process at the pilot-plant scale for more than 15 years.

And so they have a good understanding of the science and technology of the process.

Now, machinery upgrades supported by $75,000 from the state-supported Leading the Bioeconomy Initiative at Iowa State will help engineers develop an even better understanding of the art of fast pyrolysis.

“The science of pyrolysis is what you can read in a book,” said Robert C. Brown, an Anson Marston Distinguished Professor in Engineering, director of Iowa State’s Bioeconomy Institute and the Gary and Donna Hoover Chair in Mechanical Engineering. “The art of pyrolysis is actually being able to make it work in continuous, pilot-scale reactors. This entails a lot of know-how in addition to book learning.

“The support from the Leading the Bioeconomy Initiative to upgrade our pilot-scale pyrolyzer gives us an edge over our colleagues whose experience is often limited to bench-top reactors in the lab.”

Jordan Funkhouser, Lysle Whitmer and Marty Haverly, left to right, helped redesign and rebuild Iowa State's fast pyrolysis pilot plant. - Photo by Bob Mills of the Bioeconomy Institute
Jordan Funkhouser, Lysle Whitmer and Marty Haverly, left to right, helped redesign and rebuild Iowa State’s fast pyrolysis pilot plant. – Photo by Bob Mills of the Bioeconomy Institute

Whitmer said the upgrades are “from the ground up” and have created “Pyrolyzer 2.0” at Iowa State’s BioCentury Research Farm just west of Ames.

A team of graduate and undergraduate engineering students redesigned the machine to improve its efficiency, instrumentation, data collection, reliability and maintenance, Whitmer said. A major focus was making it easier and faster to clean and switch the machine from one experiment to the next. The engineers also wanted to improve the machine’s reliability over long and continuous production runs.

Whitmer said the improvements have bumped the pyrolyzer’s processing rate from 7 kilograms of biomass per hour to 10 kilograms per hour.

One way the engineers expect to increase production is by tweaking how the machine separates and collects fractions of the bio-oil produced by fast pyrolysis. Bio-oil is a complex mix of chemicals and compounds and Whitmer said it’s much easier to process when the heavier fractions are separated from the lighter ones. And now the pilot plant is collecting six fractions instead of five.

“That increases the overall yield of bio-oil and improves the quality of each fraction for recovery of more valuable chemicals like sugars, asphalt-like phenolic oligomers and acetic acid,” Brown said.

Last July, an Iowa State research team led by Brown was awarded a patent for the fractioning process. The technology has been exclusively licensed to Avello Bioenergy Inc., a startup company established by three Iowa State graduates.

Brown said a pilot plant that incorporates what Iowa State engineers have learned about fast pyrolysis could spark even more economic development for Iowa.

“Fast pyrolysis is a pathway to advanced renewable fuels from cellulosic biomass like corn stover, which Iowa has a lot of, and switchgrass, which is well suited to Iowa’s climate and soils,” he said. “What we learn in the lab can help companies commercially develop these Iowa resources.”

January 28, 2014 by Mike Krapfl

A Search Engine for Code

Kathryn Stolee
Kathryn Stolee

Writing software is kind of like solving a puzzle,” said Kathryn Stolee, the Harpole-Pentair Assistant Professor of Software Engineering.

Any programmer who has suffered long hours in search of missing code can attest to this analogy. But now, thanks to Stolee’s research and development of Satsy, a new code-specific search engine, digging up those final missing pieces has become easier than ever.

“I wanted to find a way to help programmers reuse existing code so they don’t have to re-invent the wheel.” said Stolee, who added that much of the programming code we write today has likely been written in the past. “I also wanted to assist novice programmers who don’t have much experience or formal training. I think that’s who will find the most value; people who know what they want to do, but aren’t quite sure how to do it.”

The first thing Stolee did was conduct a survey of programmers and their code searching habits to understand their needs and how to meet them. She gathered information on how often they search for code, what information they were looking for, and what tools they used.

After analyzing data from the survey, Stolee was not only surprised to learn just how frequently programmers searched for code, but she also was surprised to find out where they were searching for it. The survey revealed that Google search was the most frequently used tool among programmers, despite the numerous code-specific search engines available.

“It’s surprising, because Google wasn’t designed specifically for code search,” said Stolee. “It was designed for general search, and although it currently serves as the best tool, I think that for certain types of searches, we can do better.”

The survey results seemed to show a demand for a code-specific search engine that is accurate, efficient, and able to give Google a run for its money.

This is where Satsy comes in.

Satsy is the program that Stolee developed to help programmers search for code quickly and efficiently. Unlike Google where you search using a question or phrase, Satsy utilizes input values and output values to locate source code that best matches the programmer’s needs. By eliminating the textual query, Satsy is able to search by using the behavior of a function, rather than by the way the function is written into a search bar.

“You provide concrete examples of inputs and concrete examples of outputs for your desired code. Then, Satsy uses a constraint solver to find existing functions that satisfy the examples,” said Stolee. “It’s not easy, which may be why it hasn’t been done before, but it is more intuitive than a textual search and can achieve higher precision. By using a constraint solver, we also can find code that approximately or partially matches the examples when an exact match does not exist.”

The science behind Satsy (click to enlarge)
The science behind Satsy (click to enlarge)

Satsy scans through a library of source code called a repository, and pulls out any and all functions that satisfy the user’s initial values using an SMT solver to determine if a function matches the provided examples. A ranking system is then applied to these functions to determine which ones are most likely to satisfy the programmer’s needs.

After developing her approach, the next step in Stolee’s research was to evaluate how Satsy would hold up in practice when compared to the competition; in this case, Google and a pre-existing code-specific search engine called Merobase. Stolee gave programmers simple tasks that required them to run searches using each tool. Afterward, she collected data to determine which search engine provided the most satisfying results from the programmer’s standpoint.

Stolee’s evaluation was promising, showing that Satsy out-performed Merobase in providing relevant search results. While Google still provided the most relevant search results of three tools, the results were competitive.

When the evaluation was complete, Stolee began looking at areas to improve. One area she hopes to tweak is the ranking system used in Satsy. By increasing the accuracy and effectiveness of the ranking system, Stolee believes it could match Google.

“Google wouldn’t be as effective as it is if it didn’t have such an effective ranking system,” said Stolee. “Without a good ranking system, it’s hard for programmers to find what they want to use.”

Now, as Stolee looks toward the future, she has identified multiple “next steps” that she plans to take toward improving Satsy to make it more helpful and effective. Most importantly, she hopes to gain more knowledge about what the programmer already knows, and what information they are looking for when conducting code searches.

Stolee also is working with a senior design team to create an interface that will make Satsy more user-friendly and efficient. Once the program is fully developed, further tests can be run and measured more accurately.

Looking ahead five years, Stolee hopes to make Satsy publicly available to programmers everywhere. She also hopes that it can be adopted and used in practice by students and professionals alike.

January 8, 2014 by Brock Ascher