On October 18 the Electrical and Computer Engineering Department held its 2013 Ph.D. Poster Session, in which Akshaya Shanmugam won first place and also received the “Special Tang Award,” sponsored by the Shirley and Ting-wei Tang Endowment. Shanmugam’s faculty advisor was Christopher Salthouse, and the winning poster was entitled “Lensless Fluorescence imaging with height calculation.” The second place poster, entitled “Forest stand height inversion using spaceborne repeat-pass L-Band INSAR correlation,” was created by Yang Lei. Matthew Conte won third place with his poster entitled “Down-conversion frequency mixer implementation strategies.”

As Shanmugam explained her winning project, “Flow cytometers are laboratory instruments used to measure populations of cells. They are an essential part of treating AIDS patients and widely used in research laboratories around the world. They would be an invaluable tool for a point of care diagnostics, but traditional instruments are large, expensive, and fragile. The technique of lensless fluorescence imaging promises to make disposable flow cytometers a reality, but the strong effect of sensor-sample separation has been seen as a major hurdle. In this work, we demonstrate that this effect can be removed using straight forward image processing.”

She went on to describe her project by writing that “In this work, a phantom formed of agarose gel and fluorescent microspheres (beads) was created to represent fluorescently labeled cells at different heights. The height of each bead was then measured by shadow imaging. Next, the lensless fluorescence image was captured. Both sets of data were processed to find a correlation between the height of the bead and the shape of the fluorescence image. Finally, cells were imaged with the lensless fluorescence method.”

Lei’s advisor was Paul Siqueira and the poster dealt with spaceborne missions with Synthetic Aperture Radar (SAR) onboard, which are remarkably useful for mapping the global biomass distribution and monitoring climate change.

“In this work,” as Yang wrote, “a simplified scattering model is developed to relate the repeat-pass Interferometric SAR (InSAR) correlation magnitude to vegetation height. The dominant source of error, known as temporal decorrelation, is compensated. The inversion approach is validated utilizing JAXA’s ALOS/PALSAR (L-band SAR) data against NASA’s LVIS (LiDAR) data over the Howland forest in central Maine. A state mosaic map of forest stand height is generated for Maine through the use of an automatic mosaicking algorithm.”

Conte, whose advisor was Joe Bardin, explained that “Mixers play an important role in Radio Frequency (RF) system architectures. In most contemporary receiver systems, a gain block precedes the mixer in order to set the receiver noise floor. However, for extremely wide band integrated systems, this gain block can limit the linearity of the system. We seek to analyze the technology space and evaluate contemporary mixer implementations with an emphasis on noise figure, conversion gain, linearity, and input-referred third-order intercept point (IIP3) metrics.” (November 2013)