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Electrical and Computer Engineering

Thomas Jahns, Giri Venkataramanan, and Chris Demarco

Professors Thomas Jahns (left), Giri Venkataramanan (center), and Chris DeMarco; Associate Professor (right), Bernie Lesieutre; and Atmospheric & Oceanic Sciences Assistant Professor Ankur Desai are participating in a partnership between UW-Madison and Vestas, the world’s largest manufacturer of wind turbines. (large image)

Vestas partnership powers wind energy research

A recent partnership between the College of Engineering and Vestas, the world’s largest manufacturer of wind turbines, promises to propel wind energy research and education at UW-Madison. Under the partnership, which began in spring 2009, Vestas will provide funding to support as many as 10 graduate and undergraduate students working on wind technology projects. The company also is establishing a research and development office in Madison that will enable its researchers to work with faculty and students to conduct sponsored research projects and assist with technology transfer.

“Wind energy is a rapidly growing source of new power generation around the world,” says Professor Thomas Jahns, who co-directs the Wisconsin Electric Machines and Power Electronics Consortium and helped establish the partnership. “Key partnerships such as this one provide win-win opportunities for our faculty, students and industry partners to accelerate the development of advanced wind power technology.”

Vestas plans to support professorships at UW-Madison that will encourage innovative research and development of new curriculum materials in the alternative energy field. The ultimate objective is to use this new partnership as a foundation for launching a new multidisciplinary research center focused on integrating wind power and other renewable energy sources into the electric utility grid.

The Vestas/UW-Madison partnership already yielded a major grant from the U.S. Department of Energy for developing a new wind energy curriculum. In addition to Jahns, Professors Chris De Marco and Giri Venkataramanan, and Associate Professor Bernie Lesieutre and Atmospheric & Oceanic Sciences Assistant Professor Ankur Desai are participating in this initiative.

“The Vestas partnership is an exciting addition to the range of energy research and education at the college,” says Dean Paul Peercy. “Once we solve energy storage issues, wind power could supply as much as 20 percent of the nation’s energy needs by 2030. Our students will be highly motivated to participate in this growth industry.”

New framework yields robust circuits

New generations New generations of powerful integrated circuits, which drive most electronic devices, are produced every few years, and in each generation, the circuit components become smaller and smaller. The ever-decreasing size of components presents new design challenges for developers that can result in fabrication imperfections, especially as circuit components approach the nanoscale and become less tolerant of these imperfections. The low tolerance may mean the variations in the performance level could be too significant, making the circuits difficult to mass-produce and send to market for use in products ranging from computers and cell phones to television sets and cars.

Correcting imperfections is difficult because circuits include as many as billions of tiny components that may execute billions of commands per second — meaning developers are challenged to pinpoint exactly where and when imperfections occur. It is important, then, to prevent manufacturing imperfections early in the design process.

Assistant Professor Azadeh Davoodi has developed a mathematical framework for fabricating integrated circuits that are robust with respect to manufacturing imperfections. The framework gives developers a chance to prevent some imperfections before even creating a prototype, which could improve the integrated design process overall. Her framework is unique because it requires very little information about the manufacturer’s processes to make robust predictions. Often, manufacturers do not keep or release detailed data on their processes, and the new framework will allow designers to create circuits with fewer manufacturing errors — without knowing details about those errors.

In the next year, Davoodi plans to expand her research to creating “debugging” tools that could reduce the number of circuit prototypes developers have to create. Davoodi will research the root causes of component failures and generate predictions about future failures. This work could help developers more quickly advance circuit designs to mass fabrication. A grant from the National Science Foundation supports Davoodi’s research.

Curved photodetectors sharpen images

Professor Zhenqiang (Jack) Ma, Erwin W. Mueller and Bascom Professor of Materials Science and Engineering Max Lagally and University of Michigan Professor Pallab Bhattacharya have developed a flexible light-sensitive material that could revolutionize photography and other imaging technologies.

When a device records an image, light passes through a lens onto a photodetector array — a light-sensitive material like the sensor in a digital camera. However, a lens bends the light and curves the focusing plane. In a digital camera, the point where the focusing plane meets the flat sensor is in focus, but the image becomes more distorted the farther it is from that focal point. That’s why some photos can turn out looking like images in a funhouse mirror. High-end digital cameras correct this problem by incorporating multiple panes of glass to refract light and flatten the focusing plane. However, such lens systems — like the mammoth telephoto lenses sports photographers use — are large, bulky and expensive. Even high-quality lenses stretch the edges of an image somewhat.

Inspired by the human eye, Ma’s curved photodetector could eliminate that distortion. In the eye, light enters though a single lens, but at the back of the eye, the image falls upon the curved retina, eliminating distortion. “If you can make a curved imaging plane, you just need one lens,” says Ma. “That’s why this development is extremely important.”

The team creates curved photodetectors with specially fabricated nanomembranes — extremely thin, flexible sheets of germanium, a very light-sensitive material often used in high-end imaging sensors. Researchers then can apply the nanomembranes to any polymer substrate, such as a thin, flexible piece of plastic. Currently, the group has demonstrated photodetectors curved in one direction. Ma plans next to develop hemispherical sensors.

University of Wisconsin-Madison College of Engineering University of Wisconsin-Madison