Birds, beets, and morphing aircraft
The police officer’s face melts. His menacing gaze merges into molten runnels. In seconds, the man becomes a giant, liquid-silver slug, pouring through the shattered window of a helicopter and, just as quickly, resuming his original form in the pilot’s seat.
“Nothing about this scenario,” says Lisa Mauck Weiland, “violates the laws of physics.”
Shape-changing robots like the one in this scene from the film Terminator 2 don’t seem all that far-fetched to Weiland—her research at Pitt aims to move morphing technology out of science fiction and into the realm of possibility.
To explain her work, Weiland rummages through her desk for something smart. “I usually have some great examples,” she says apologetically. As she shifts stacks of paper, a small, silver airplane pendant around her neck swings in a suspended nosedive. Empty-handed, she thinks for a moment. “Okay, for example,” she says. “Silly putty.”
Weiland, assistant professor in Pitt’s Department of Mechanical Engineering, works with smart materials. “A smart material is any material that will do something extra beyond what you would expect,” she says. Silly putty isn’t a smart material because “if I push on it, it’s going to squish. We expect that. If it also lit up or generated an electric field, that would make it a smart material.”
Smart materials have been in use for years, appearing even in relatively primitive devices such as dot-matrix printers and record players. Now, Weiland is part of a national team using smart materials to pioneer the next generation of aeronautic technology for the U.S. Department of Defense—a shape-shifting airplane that behaves like a bird.
Imagine an eagle soaring high above a field. It spots movement in the grass below: potential prey. Instantly, it tucks its wings and dives toward its target. Now imagine a plane that could alter its shape to do the same thing—a broad-winged, high-altitude reconnaissance aircraft able to locate an enemy on the ground and morph into a sleek, maneuverable fighter jet to attack.
“If someone had told me before I joined this team that we’d be proposing what we have proposed, I would have replied that it was not physically possible,” says Weiland. But the team’s combined expertise led her to quickly change her belief.
Current airplane wings, with their rigid forms and sharp-angle hinges, are nowhere near as aerodynamic as their avian counterparts. “If you think about a bird of prey, when it dives, it pulls its wings back,” says Weiland. “Take an F-111 [a military fighter jet]. Its wings can sweep forward or pull back. But a bird does more than pull its wings forward and back. There are angle changes; there’s musculature that changes how fat the lead angle is on the wings.”
Aerospace engineers have figured out a number of ways to mimic a bird’s wings on an airplane, Weiland says. Now, she’s working on one of the biggest hurdles to developing a morphing aircraft: creating a skin for the plane. “The skin has to simultaneously be able to deform a lot but also be able to withstand tremendous loads. It has to be both flexible and tough,” says Weiland.
One possible solution comes from the vegetable world. Weiland’s team is investigating the use of cell parts derived from beets that, when affixed to a substrate, form the basis for a protean skin. They also are examining the use of a mesh of polymers that can become rigid or flexible with the application of an electric field, like a tightly woven net that can instantly stiffen or loosen.
Dominating Weiland’s lab is a massive, blue steel box in which she manipulates strips of smart material skin—resembling lengths of cloudy plastic—in variable humidity and temperatures ranging from –70 to 250 degrees Celsius, seeking a material that can function in extreme conditions. On the countertop nearby is a pile of twisted, stretched, and broken strips, a record of painstaking progress. Weiland guesses that the realization of a true morphing aircraft is at least 20 years away.
In the meantime, Weiland is not only working on developing smart material applications, but she’s also making sure that the next generation of researchers will be in on the effort. When students visit her lab, she often asks them, “What appeals to you more: morphing aircraft or saving the environment?” With smart materials, both are possible: Some of the same polymers that Weiland is using to develop morphing aircraft skin are used in pollutant-free fuel cell technology.
Just a little something extra beyond what you would expect. —Bo Schwerin
Decision-making with the head... and heart
A young Pitt law professor named Jules Lobel is writing briefs for a law firm representing the plaintiffs in the U.S. Supreme Court case of Regan v. Wald, which argues that U.S. citizens have the right to travel to Cuba. Lobel sees the case as a slam dunk because he believes that a citizen’s right to travel is protected by the Fifth Amendment. But in a 5-4 decision, the Supreme Court rules that the executive branch has the right to limit travel for foreign policy reasons.
The ruling took place in 1984 during the Cold War, when tensions between the United States and Cuba were particularly high. The case and the circumstances made Lobel wonder: Did emotion play a role in the high court’s decision?
Lobel has since examined the dynamic between deliberative decision-making and emotional response in the areas of economics, politics, and law. Together with George Loewenstein, economics and psychology professor at Carnegie Mellon University, Lobel fleshed out his observations in a paper titled “Emote Control: The Substitution of Symbol for Substance in Foreign Policy and International Law,” published in the Chicago-Kent Law Review last year.
Lobel and Loewenstein argue that all of us—individually and as collective societies—use two qualitatively different neural processes to make decisions. One is a carefully considered, purposeful process of weighing the costs and benefits to achieve well-defined goals—what the professors refer to as the “deliberative control” over behavior. In contrast, the second decision-making process, “emote control,” is fast, reflexive, and influenced by feelings such as fear, sadness, and anger.
According to Lobel, emote control is more likely to kick in when certain factors are present, such as time restraints, a decision-maker’s identification with a victim, or subjecting a decision-maker to vivid imagery like repeated news footage of a terrorist attack. The problem is, the professors say, that many situations—such as terrorist threats—that tend to evoke emote control are those that require deliberative control the most.
But this is not to say that deliberative and emote control are mutually exclusive.
“Human behavior is not under the sole control of emotion or deliberation but results from the interaction of these two processes,” Loewenstein says.
Politicians and other policy makers often use both their heads and their hearts when making decisions, Lobel says. He also notes that there are times when emote control needs to take over. If a country is attacked, for example, there may be no time for controlled deliberation.
“Emotional reactions aren’t bad,” Lobel says. “They can bring out the best as well as the worst in people. We just have to be aware of when they are influencing our behavior and understand they have pitfalls.” —Allison Schlesinger