Grad Profile

Skydiving into a PhD

Jeff Zehnder — Thu, 16 Oct 2025 18:28:30 +0000

Skydiving into a PhD Jeff Zehnder Thu, 10/16/2025 - 12:28

Jeff Zehnder

Harris at the Phononics 2023 conference in
Manchester, England.

Adam Harris is advancing the frontiers of aerodynamics as a non-traditional student, finishing up a doctoral program in which he never expected to enroll.

“I’m writing computational fluid dynamics and finite element codes to study flow control by phononic materials and structures. A phonon is the quantum of vibrational energy, a quasi-particle that could give birth to a whole new species of technology,” Harris said.

A PhD student in the materials science and engineering program, Harris began his college journey in 2012 as a psychology major, but his time at CU ��ý�� did not last long.

“I didn’t show up to classes and just really didn't care. I was placed on academic probation my first semester and academic suspension my second,” Harris said.

A native of Miami, he elected to stay in ��ý��, working in construction and landscaping. In 2014, Harris enrolled at Front Range Community College for an associate’s degree in business.

Skydiving Hobby

Harris also started skydiving as a hobby, hanging out at Vance Brand Airport in Longmont, making up to 10 jumps a day. Eventually, he was hired there for a paid ground crew position.

“I was surrounded by people who were monitoring weather, maintaining aircraft, and discussing flight mechanics. I started teaching myself basic aerodynamics, watching TED talks and physics documentaries online. It all became more and more interesting to me,” he said.

After finishing at Front Range, Harris decided to continue onto a four-year business degree at CU ��ý��. Because of his past suspension, enrolling required an appointment with an admissions advisor. The meeting would change the direction of his life.

Changing Gears

“I told her about all the science, engineering, and physics I was being exposed to. She looked at me suspiciously and said, ‘Are you sure you want to study business?’ Nope, put me down for physics,” Harris said.

He steamrolled through his courses, earning As and Bs in subjects where he had previously shown little interest. In the five years since his first stint at CU ��ý��, Harris had grown significantly.

“Turns out I really love math. I think my success was a product of motivation and how much I enjoyed where I was, the people around me, what I was learning, and relevance to my passions. I have a GPS in my skydiving helmet and I would always try to connect course concepts to data acquired from wingsuit flights,” he said.

As he was completing his bachelor’s, a connection with Mahmoud Hussein, a professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences, opened the door to graduate school.

Graduate School

“I was still enjoying classes but I paid for undergrad myself, so I didn’t want to continue accumulating debt. I started talking to Mahmoud, and when I learned engineering PhD programs cover tuition and living expenses, there was no question. What an opportunity,” Harris said.

Hussein became his graduate advisor as Harris earned two master’s degrees – in aerospace and materials science. He expects to finish his PhD in materials science next spring.

His dissertation is centered on phononic subsurfaces (PSubs), which could lead to radical increases in fuel economy for jet aircraft and hypersonic vehicles. It has been a focus of Hussein’s lab for 15 years, beginning at the theoretical level and now approaching the applied stage, thanks in part to a major Office of Naval Research grant awarded last year.

“This started with purely computational work and now we’re 3D printing PSubs. We can validate the PSub’s tuned frequency response with a laser vibrometer, and we have candidate prototypes that yield the response we expect. We’re going to begin the first wind tunnel tests in collaboration with the Experimental Aerodynamics Laboratory at CU ��ý�� very soon,” Harris said.

What's Next?

As he writes his dissertation, Harris’s research background offers a wealth of career opportunities, but he is hoping for a particular dream job that would combine fluid dynamics and computational modeling with his love of skydiving.

It may sound like a fantasy. It is not.

“There’s a company in California that builds parachutes used for space craft atmospheric re-entry,” Harris said. “The job description is everything I’m doing at CU ��ý��, plus a requirement of parachute rigging experience, which I have.”

Wherever Harris lands, he is a long way from his beginnings in ��ý�� as an 18-year-old psych major.

“I think this is where I was supposed to be all along,” Harris said. “I just wasn’t aware of it back then. The synchronicity is really cool.”

Additional Photos

Harris BASE jumping in La Mousse, Switzerland.

Gliding into a canyon

Harris skydiving over Vance Brand Airport in Longmont.

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Countering space radiation materials damage with machine learning

Jeff Zehnder — Tue, 24 Jun 2025 21:11:30 +0000

Countering space radiation materials damage with machine learning Jeff Zehnder Tue, 06/24/2025 - 15:11

Jeff Zehnder

Jason Rivas is researching materials at the atomic level to improve reliability and resistance of electronics to space radiation.

A PhD student in materials science and engineering at the ��ý��, Rivas is tackling a problem that faces any technology that goes beyond the confines of Earth’s atmosphere: damaging bursts of radiation from our sun and other stars.

“We’ve gotten good at shielding electronics,” he said. “But we’re not good at making things radiation hard by design. You can shield anything if you put enough iron, steel and lead around it, but if you add that to a satellite, how many millions of dollars extra is it to launch that weight?”

Working with his PhD advisor, Associate Professor Sanghamitra Neogi, Rivas has earned a major graduate fellowship from the Draper Laboratories in Cambridge, Massachusetts. Through the program, he intends to use computational materials modeling expedited by machine learning to advance the science of space hardened electronics.

The fellowship provides four years of funding for his PhD, as well as access to scientists and engineers at Draper Labs.

“We want to make this research faster and cheaper. Currently the testing requires physically using a neutron beam in a radiation environment. It’s expensive. We think we can change that using with machine learning,” Rivas said.

Developing computational models to map out the effects of ionizing radiation on materials requires exploring the problem at the level of individual atoms.

“We want to determine how much degradation a transistor can stand. It’s called displacement damage. If radiation hits an atom in a material, it displaces that atom, which hits another atom, which hits another atom. How well can that material then return to its original form,” he said.

Tackling the challenges of radiation at an atomic level requires analysis using supercomputers, like CU ��ý��’s Alpine system. If the work is successful, it could aid researchers across the spectrum of engineering fields. That prospect is appealing to Rivas, and part of why he chose to pursue a PhD in materials science and engineering: the interdisciplinary nature of the work.

“It’s this intersection of all these different needs. Materials are everywhere. It’s problem solving that means something to the real world,” he said.

Rivas has long been interested in math and science. As a child, he was encouraged by positive teachers and through exploring YouTube channels like 3Blue1Brown, which outlines math problems visually.

“I had a really good calculus teacher in high school. She inspired me. Calculus is just beautiful. Math tells you how the world works,” Rivas said.

Rivas earned his bachelor’s in physics and computer science from Austin Peay State University, which is located near where he grew up in Tennessee. After completing his undergraduate degree, he was drawn to earn a PhD by the prospect of becoming an educator and to break new ground in science.

That eventually led him to ��ý�� and the materials science and engineering program.

“I want to teach in a college setting. You sort of need a PhD to do that,” Rivas said. “The jobs that come with it are also pretty interesting. Doing research, the problems are self-defined. I get bored doing the same thing everyday.”

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Grad student researching 3D printing and ultrasound for medicine

Jeff Zehnder — Thu, 13 Feb 2025 21:05:50 +0000

Grad student researching 3D printing and ultrasound for medicine Jeff Zehnder Thu, 02/13/2025 - 14:05

Jeff Zehnder

Lily Mortensen is advancing research at the leading edge of biomedicine, working on new ways to improve human health.

A materials science and engineering PhD student at the ��ý��, Mortensen is investigating ways to combine 3D printing and ultrasound technology to benefit individuals suffering from certain medical conditions.

The eventual goal is to be able to inject a liquid polymer into the body and then use ultrasound frequencies to harden the material without cutting open the skin.

“Repairing a hole in the heart right now requires surgery,” Mortensen said. “What if you could inject something and repair it at a distance? Ultrasound is so cool because you can use it through a barrier like skin. Instead of cutting a patient open, we could inject a small amount of 3D printed material as a liquid and repair a defect in place.”

It is still very early research, but is the subject of investigation by scientists and engineers across the United States because of its great potential.

“We can choose polymers and components which are bio inert/compatible, so the body doesn’t attack it,” Mortensen said. “And the properties of ultrasound that make it good for noninvasive human examination, to see something under the skin, make it good for this too.”

It is still early research, with Mortensen testing various types of polymer inks and experimenting with the ultrasound parameters to determine the best compounds and intensities to cure the materials in place.

"It’s very hands-on. One of the issues I’m trying to solve is ultrasound printing has acoustic streaming, where the ultrasound force is so intense it causes the liquid to flow, but if it flows out of the area you want, that’s not giving us good resolution or focal size. We’ve made some progress, but it’s definitely difficult,” she said.

Mortensen utililizing ultrasound-induced polymerization to 3D print the CU ��ý�� Ralphie Logo through a clear barrier.

Working at the forefront of a research area presents unique challenges – notably that there is limited published research to fall back on.

“I’m building off other people's work, but branching into areas where I have to figure it out myself because nobody has figured it out yet,” she said.

Now in the third year of her PhD program, Mortensen did not always envision herself earning an advanced degree. After completing her bachelor’s in materials science at the University of Idaho, she found a job at a semiconductor company in upstate New York. It was engaging work, but Mortensen realized she wanted more.

“I learned a lot there, and I liked it, but I realized the work that I found really interesting was the research and development projects, and they were all handled by PhDs. So I applied to PhD programs,” she said.

She was drawn to CU ��ý�� by the variety of faculty research in the materials science program, the university’s culture, and the Rocky Mountains.

“Certain institutions are not known for treating their PhD students well. CU ��ý�� has a really good culture, and ��ý�� has great outdoor access and lots of interesting people,” she said.

Mortensen is currently finalizing her first research paper as lead author, on new types of inks that will enable ultrasound 3D printing of hydrogels. She is also hopeful her current work will lead to a patent application.

“This is a really cool technology, but there’s always the possibility it won’t work out,” she said. “That’s a chance with any research, but it’s where I want to be. Working in research and finding the next new thing.”

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