By the end of 1994, the papers and books of engineering professor Thomas Graedel, a specialist in industrial ecology, had been cited more than 2,200 times, placing his citation record among the top 1 percent of all active scientists.

Thus it was hardly surprising when the National Academy of Engineers elected Graedel and fellow Yale professor A. Stephen Morse — a noted scholar of electrical engineering and computer science — to join its ranks, honoring their seminal contributions to their respective fields.

“I’m surprised they haven’t [elected Graedel] before,” said chemical engineering professor Gary Haller, who doubles as the master of Jonathan Edwards College. “He’s the father of industrial ecology.”

Election to the academy, whose main mission is to provide advice to the federal government on engineering issues, is one of the highest accolades in the field of engineering.

Academy membership honors those who have made “important contributions to engineering theory and practice” and those who have demonstrated “unusual accomplishment in the pioneering of new and developing fields of technology,” according to the academy’s Web site.

The election of Graedel and Morse — who are among only 74 engineers nationally to be selected this year — brings Yale’s membership from three to five. The other three academy members at Yale are electrical engineering professor Jerry Woodall, professor Katepalli Sreenivasan of the Mechanical Engineering Department, and Paul Fleury, the dean of the Faculty of Engineering.

Graedel joined the Yale faculty in 1997 and was one of the first professors in the United States to study what is now called industrial ecology.

“What we call industrial ecology is the science and technology of sustainability,” he said. “What we study is how to accomplish the activities that society that would like to have happen, like the heating and cooling of a home, while minimizing the impact on the environment.”

His environmental assessment matrix, developed after a successful 27-year career with AT&T Bell Laboratories, is now a standard industrial tool for assessing the environmental characteristics of products, processes and facilities.

“We try to understand how we use materials and how we might think about addressing our whole technological structure to maximize use and reuse of materials, rather than our present practice of ‘dig it up, use it and throw it away,'” Graedel said.

As well as publishing several foundational works in the area of industrial ecology, Graedel edits the Journal of Industrial Ecology, the premier journal in the burgeoning field.

While Graedel works to protect the environment in the School of Forestry and Environmental Sciences, on the other side of campus, Morse develops unmanned craft to explore some of the Earth’s most remote parts.

Morse has been a member of Yale’s electrical engineering faculty since 1970. His most recent work has focused on the coordination and control of the large grouping of mobile autonomous agents.

Three years ago, the Institute of Electrical Engineers and Engineering presented Morse with the Control Systems Award for his work in the area of automatic control. The award is the highest in the field of control systems.

“I’ve know professor Morse for a very long time, and I know that his work has been very well regarded,” said Werner Wolf, a physics and engineering professor.

Three professors from Princeton, one foreign, and another from the University of Pennsylvania were also elected this year.