No abstract

The National Institute of Standards and Technology (NIST) has a suite of research projects addressing risk reduction in Wildland Urban Interface (WUI) communities. The NIST WUI Team was invited by California Department of Forestry and Fire Prevention (CAL FIRE) to collect post incident data from the California October 2007 fires. Early on, the NIST WUI Team initiated a case study within the Witch Fire perimeter. The case study is focused on the Trails development at Rancho Bernardo, north of the city of San Diego. There were 270 homes in the Trails community, with 242 within the fire perimeter. Of these, 74 homes were completely destroyed and 16 were partly damaged. Field measurements included structure particulars, specifically roof type, proximity of combustibles to the structure, and damage to wildland and residential vegetation. Documentation included over 11 000 digital images. The data collected and the data analysis are divided into two papers. The first paper, NIST TN 1635 addressed the event timeline reconstruction and general fire behavior observations. This second paper investigates the effect of structure attributes, landscaping characteristics, topographical features and potential wildland fire exposure on structure survivability.

No abstract

29the Communication Research Centre Canada, in close collaboration with the University of Ottawa. Since then, the concept has been applied to the design of ultra-thin lenses having comparable effi ciency to a shaped dielectric lens, the leading conventional technology. In this paper, we fi rst provide a brief historical review of lenses and related technologies, from soon after World War II to the present. We then present the phaseshifting surface concept and its implementation, followed by a selection of prototypes that we have developed to demonstrate phase-shifting surface performance and capabilities. The paper ends with a general discussion presenting the current and future challenges of phase-shifting surface development, fol lowed by a conclusion. Historical ReviewMicrowave collimating lenses fi rst used as antenna elements were made from homogeneous dielectric material, and were based on the transposition of optical lenses in the microwave frequency range [3]. Despite providing a high aperture effi ciency, they suffered from major physical drawbacks: they were thick, heavy, bulky, and expensive to fabricate. AbstractPhase-shifting surfaces (PSSs) developed in recent years are reported. Research and development on these phaseshifting surfaces are set in the historical context of prior-art free-standing lensing devices, as well as in the context of recent studies performed by other research groups. In addition, initial work on a phase-and amplitude-shifting surface (PASS), an extension of the phase-shifting surface, is demonstrated in a beam-shaping application.

No abstract