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Cover of the Fall 2010 Annual Report issue
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FALL 2010
ANNUAL REPORT

COLLEGE DEPARTMENTS

Electrical and Computer Engineering

Eagle eye: Bioinspired optics provide new views of the body

Difeng Zhu and Hongrui Jiang. Photo by David Nevala.

Associate Professor Hongrui Jiang (right) with graduate student Difeng Zhu. Photo by David Nevela. view larger image

Inspired by the eyes of various animals, Associate Professor Hongrui Jiang and his collaborators are creating innovative optical technologies for surgical tools, surveillance and electronic devices. “Instead of just duplicating natural designs, we want to understand what features are beneficial in what way and combine those benefits to create something with even more functionality,” he says.

Image of a six-element microlens array

Image of a six-element microlens array on a dome with a diameter of 18 mm. Hongrui Jiang fabricated multiple liquid-based tunable-focus microlenses on a hemisphere, resultng in a large field of field of view. With dimensions in millimeter range, this curvilinear microlens array could have many surgical applications. view larger image

For example, current endoscopes have a fixed lens at the tip, giving the tool a limited range of vision. When a doctor performs a colonoscopy, the fixed lens makes it difficult to detect potentially cancerous polyps in the folds of the colon. Jiang and his team have developed a dome structure covered in lenses that resembles a dragonfly eye. Unlike the insect, each lens on Jiang’s dome is tunable, potentially giving the device more than 270 degrees of focused vision. This could reduce the rate of missed polyps and the overall time of the procedure.

Jiang and collaborators from the UW-Madison surgical department have received funding from the Wisconsin Institute for Discovery for the research. In addition to traditional endoscopes, the team is working to optimize laparoscopy tools and capsule endoscopes with tunable lenses. “We can have prototypes of these surgical tools in about five years,” he says.

Jiang also has received an Emerging Frontiers in Research and Innovation grant from the National Science Foundation to create intelligent micro optical imaging systems. With collaborators from UW-Madison, University of California, Davis, and University of Illinois at Urbana- Champaign, Jiang is creating a ball covered with small cameras, called multi-microcamera arrays. Partly inspired by eagle eyes, each of the small cameras can focus as needed, creating a device with multiple foveae (focus points) and 360 degrees of vision.

Additionally, this team is studying reflecting superposition compound eyes, like those of a lobster, to build three dimensional, microscale mirror- box structures on Jiang’s optical domes. The mirrors will increase image resolution and light intensity.

Smart tech for smart communications

Decorative photo - data

As smart phones and other wireless devices become ever more prevalent, the amount of data flowing through wireless networks is rapidly increasing. This data flow eventually connects back to the Internet, typically via cell towers that connect to base stations through fiber optic cables. As demand increases, bottlenecks in the base stations can occur and cause delays, but simply laying more cable isn’t always feasible. Instead, interest is growing in ways to send information at very high rates — tens or hundreds of gigabits per second — across high frequency (60-100GHz) microwave wireless links.

Professor Akbar Sayeed is developing a new type of this kind of wireless link. Along with Assistant Professor Nader Behdad, Sayeed is designing a hybrid analog-digital architecture for communicating information. Initial results suggest an order of magnitude improvement in power and bandwidth efficiency over current technologies.

Sayeed’s technology will combine the benefits of a variety of current antenna systems. The new architecture will take the form of a dish illuminated with feed antennae precisely controlled to send multiple beams containing multiple independent data streams, allowing for significantly increased data rates. Sayeed also will create a new kind of analog-digital interface to map the digital signal streams onto the dish surface to multiplex (combine) data in streams in various directions.

The new dishes could form a network of high bandwidth wireless links, which cannot be done with current technologies. This network could provide high bandwidth links to rural areas in the United States or developing countries. The technology also can route data to base stations with lower traffic, which would ease bottlenecks in metro areas, and take better advantage of the available electromagnetic spectrum.

Sayeed is committed to finding cost-efficient ways to develop the technology. The Wisconsin Alumni Research Foundation has provided initial funds for a prototype, which he anticipates will be complete in the next couple of years. Once a working prototype is ready, several companies associated with major service providers could partner with Sayeed to commercialize the technology.

Engineering the future of energy policy

Decorative photo - wires

Decorative photo - wires view larger image

On August 14, 2003, transmission lines in Ohio drooped into trees, causing a chain reaction that resulted in a record blackout across the Northeastern United States and part of Canada, affecting more than 50 million customers.

Prompted in part by the blackout, the U.S. Congress passed the Energy Policy Act in 2005, which included a statute that shifted responsibility for maintaining reliability in the electric grid from industry to the federal government. The legislation directed the Federal Energy Regulatory Commission, or FERC, to oversee reliability in the nation’s bulk power system.

However, the statute did not articulate which facilities actually make up the U.S. bulk power system and, therefore, which facilities fall under FERC jurisdiction. To address this basic policy question, the agency invited a group of researchers led by Associate Professor Bernard Lesieutre provide input.

The current rule of thumb for determining how important a facility is to the electric grid is guided by the voltage at the facility. Facilities with higher voltage levels are assumed to be more important to the electric grid.

Lesieutre’s team has developed an alternative, more nuanced model that evaluates how facilities are connected and the electrical properties of various networks. The new model generates a list that ranks power facilities in order of the effect on the overall electric grid if a particular facility goes offline. The team is working on the final report of its findings, which created grid-impact scenarios for more than 66,000 facilities located east of the Rocky Mountains, excluding facilities in Texas. “Even if FERC chooses not to adopt this approach, it’s a great project because we’re informing government by providing technical input. That’s what we as engineers should be doing,” says Lesieutre. “The structure of the electric energy industry has been going through fundamental changes in the last 20 years, and we need to be involved and cognizant of these changes.”

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