Habitat Characteristics of Polar Bear Terrestrial Maternal Den Sites in Northern Alaska

Polar bears (Ursus maritimus) give birth to and nurture their young in dens of ice and snow. During 1999-2001, we measured the structure of 22 dens on the coastal plain of northern Alaska after polar bear families had evacuated their dens in the spring. During the summers of 2001 and 2002, we revisited the sites of 42 maternal and autumn exploratory dens and recorded characteristics of the under-snow habitat. The structure of polar bear snow dens was highly variable. Most were simple chambers with a single entrance/egress tunnel. Others had multiple chambers and additional tunnels. Thickness of snow above and below dens was highly variable, but most dens were overlain by less than 1 m of snow. Dens were located on, or associated with, pronounced landscape features (primarily coastal and river banks, but also a lake shore and an abandoned oil field gravel pad) that are readily distinguished from the surrounding terrain in summer and catch snow in early winter. Although easily identified, den landforms in northern Alaska were more subtle than den habitats in many other parts of the Arctic. The structure of polar bear dens in Alaska was strikingly similar to that of dens elsewhere and has remained largely unchanged in northern Alaska for more than 25 years. Knowledge of den structure and site characteristics will allow resource managers to identify habitats with the greatest probability of holding dens. This information may assist resource managers in preventing negative impacts of mineral exploration and extraction on polar bears.Les ourses polaires (Ursus maritimus) donnent naissance et nourrissent leurs petits dans des tanières de glace et de neige. De 1999 à 2001, on a mesuré la structure de 22 tanières situées sur la plaine côtière de l'Alaska septentrional après que les familles d'ours polaires eurent évacué leurs tanières au printemps. Au cours des étés de 2001 et de 2002, on s'est à nouveau rendus sur les sites de 42 tanières de mise bas et d'exploration automnale et on a mesuré les caractéristiques de l'habitat situé au-dessous de la neige. La structure des tanières d'ourses polaires variait considérablement. La plupart étaient de simples cavités qui possédaient un tunnel servant à la fois d'entrée et de sortie. D'autres comportaient plusieurs salles et des tunnels supplémentaires. L'épaisseur de la neige au-dessus et au-dessous des tanières était très variable, mais dans la plupart des cas, la couverture de neige était inférieure à 1 m. Les tanières étaient situées sur des reliefs prononcés ou y étaient associées (surtout les rives côtières ou les berges de fleuves, mais aussi le bord d'un lac et le remblai de gravier d'un champ pétrolifère abandonné), qui se détachent nettement du paysage alentour en été et qui retiennent la neige au début de l'hiver. Même si elles étaient facilement identifiables, les formes de relief propices à l'établissement de tanières dans l'Alaska septentrional étaient plus discrètes que les habitats de tanières situés dans bien d'autres régions de l'Arctique. La structure des tanières d'ourses polaires en Alaska offrait une ressemblance frappante avec celle des tanières creusées ailleurs et elle est restée largement inchangée dans le nord de l'Alaska pendant plus de 25 ans. Les connaissances sur la structure des tanières et les caractéristiques des sites permettront aux gestionnaires de ressources de distinguer les habitats qui sont le plus susceptibles d'abriter des tanières. Cette information peut aider ces gestionnaires à prévenir les retombées négatives sur l'ours polaire de l'exploration et de l'exploitation minières

Linear optimization of frequency spectrum assignments across systems

Development and acquisition of naval communication, data, and radar systems for ships is an almost entirely modular process. For this reason, virtually all existing systems have separate controllers, antennas, and transmitters. However, future systems could use existing planar antennas that operate across a range of frequencies and create a variety of complex waveforms, eliminating the need to develop separate antennas and transmitters. Additionally, frequency use plans are expensive in terms of time and effort to develop and change. The Integrated Topside (InTop) joint Navy industry open architecture study published in 2010 described the need for an integrated sensor and communication system that is modular, scalable, and capable of performing multiple functions. Such a system requires a scheduling and frequency deconfliction tool that is capable of representing the current antenna configuration and matches those capabilities with requests for frequency space and time. This thesis describes SPECTRA, an integer linear program that can prioritize and optimize the scheduling of available antennas to deconflict time, frequencies, systems and capabilities. It can be uniquely tailored to any platform including naval warships, aircraft, and ground sites.http://archive.org/details/linearoptimizati1094548520Outstanding ThesisLieutenant, United States NavyApproved for public release; distribution is unlimited

Conducting expeditionary operations in the contested littorals

Reissued 21 Oct 2015 to revise figure cross references in body text.The United States armed services have identified capability gaps in the areas of company-sized raid and sustainment operations in contested littoral environments. Multiple joint platform packages can be employed to provide the required mission capabilities to fill the gap. This thesis identifies the operational, functional, and physical architecture and effectiveness of mission packages necessary to provide capabilities associated with littoral sustainment operations. Physical architecture configurations are evaluated using discrete event modeling. Cost and performance estimates for the mission packages are presented in order to provide the decision maker tools for identifying which alternative provides the most cost-effective solution for the needs of a scenario’s stakeholders. This thesis report concludes by identifying potential assets that would provide cost-effective support of littoral operations. Feasible alternatives provide varying levels of effectiveness in terms of average deployment time and percentage of threats successfully affected.http://archive.org/details/conductingexpedi1094546910Approved for public release; distribution is unlimited