Polarization techniques for mitigation of low grazing angle sea clutter

Maritime surveillance radars are critical in commerce, transportation, navigation, and defense. However, the sea environment is perhaps the most challenging of natural radar backdrops because maritime radars must contend with electromagnetic backscatter from the sea surface, or sea clutter. Sea clutter poses unique challenges in very low grazing angle geometries, where typical statistical assumptions regarding sea clutter backscatter do not hold. As a result, traditional constant false alarm rate (CFAR) detection schemes may yield a large number of false alarms while objects of interest may be challenging to detect. Solutions posed in the literature to date have been either computationally impractical or lacked robustness. This dissertation explores whether fully polarimetric radar offers a means of enhancing detection performance in low grazing angle sea clutter. To this end, MIT Lincoln Laboratory funded an experimental data collection using a fully polarimetric X-band radar assembled largely from commercial off-the-shelf components. The Point de Chene Dataset, collected on the Atlantic coast of Massachusetts’ Cape Ann in October 2015, comprises multiple sea states, bandwidths, and various objects of opportunity. The dataset also comprises three different polarimetric transmit schemes. In addition to discussing the radar, the dataset, and associated post-processing, this dissertation presents a derivation showing that an established multiple input, multiple output radar technique provides a novel means of simultaneous polarimetric scattering matrix measurement. A novel scheme for polarimetric radar calibration using a single active calibration target is also presented. Subsequent research leveraged this dataset to develop Polarimetric Co-location Layering (PCL), a practical algorithm for mitigation of low grazing angle sea clutter, which is the most significant contribution of this dissertation. PCL routinely achieves a significant reduction in the standard CFAR false alarm rate while maintaining detections on objects of interest. Moreover, PCL is elegant: It exploits fundamental characteristics of both sea clutter and object returns to determine which CFAR detections are due to sea clutter. We demonstrate that PCL is robust across a range of bandwidths, pulse repetition frequencies, and object types. Finally, we show that PCL integrates in parallel into the standard radar signal processing chain without incurring a computational time penalty

Using self-management to control seizures

The aim of this study was to develop, deliver and evaluate the impact of an education intervention regarding lifestyle self-management in the control of seizures, health related quality of life (HRQoL), satisfaction with life and resilience for adults with epilepsy

Five Design Challenges

PLEASE NOTE: Where applicable, the audio has been removed from this file due to copyrighted material. The garments shown here represent the Classes of \u2713, \u2712 and \u2711 . The garments were created in response to the following five design challenges: Sophomores, Class of \u2713: Re-Innovative Design: explore the properties of recycled materials other than fabric while creating a wearable piece. Print Design Project create a garment that makes optimal use of printed fabric designed by a RISD Textiles student. Juniors, Class of \u2712: Knitwear Design: explore the properties of knits and design cut-and-sew and machine-knit garments. Tailoring Project: interpret traditional tailoring techniques to create a look with a jacket. Seniors, Class of \u2711: Cocktail Collection: design a collection of contemporary cocktail apparel in collaboration with the current RISD Museum exhibition Cocktail Culture: Ritual and Invention in American Fashion, 1920-1980