Showing papers on "Occupancy published in 1989"

Using occupancy grids for mobile robot perception and navigation

Abstract: An approach to robot perception and world modeling that uses a probabilistic tesselated representation of spatial information called the occupancy grid is reviewed. The occupancy grid is a multidimensional random field that maintains stochastic estimates of the occupancy state of the cells in a spatial lattice. To construct a sensor-derived map of the robot's world, the cell state estimates are obtained by interpreting the incoming range readings using probabilistic sensor models. Bayesian estimation procedures allow the incremental updating of the occupancy grid, using readings taken from several sensors over multiple points of view. The use of occupancy grids from mapping and for navigation is examined. Operations on occupancy grids and extensions of the occupancy grid framework are briefly considered. >

Environmental evaluation of the Portland East Federal Office Building preoccupancy and early occupancy results

Abstract: This report describes the results of the preoccupancy and early first year occupancy tests of the Portland East Federal Building. The Nation^ Institute of Standards and Technology installed a diagnostic center in the newly constructed federal office building in Portland OR. The diagnostic center was used to determine the building’s air infiltration and ventilation rates, the building envelope tightness, interzone air movement, and the levels of indoor contaminants. The indoor contaminants measured included carbon dioxide, carbon monoxide, respirable particulates, formaldehyde, radon and volatile organic compounds.

Co-occupancy of a den by a pair of Great Basin black bears

Abstract: —An adult male and an adult female black bear (Ursus americanus) were found in the same den in the Carson Range of the Sierra Nevada in Nevada. Co-occupancy of dens is very rare, and such behavior has never been previously reported for adult bears of opposite sex. Black bears are solitary animals except when mating, accompanied by cubs, or investigating areas of abundant, clumped food sources such as garbage dumps. They den almost exclusively as solitary individuals except for females accompanied by newborn cubs or yearlings (Beecham et al. 1983, Johnson and Pelton 1979, Lecount 1983, Rogers 1987, Schwartz et al. 1987, Tietje and Ruff 1980); however, Schwartz et al. (1987) reported unusual cases of co-occupancy of black bear dens. They found four instances of mothers denning with twoand four-year-old daughters and an additional case in which a mother and her yearling male denned with a two-year-old female that was not her offspring. Two reports of cannibalism on adult female bears by larger bears (Rogers 1987: 54, Tietje et al. 1987) suggest that group denning should be avoided, especially by adult members of the opposite sex. Adult males are usually much larger than adult females and thus more capable ofcannibalism. In this report we describe co-occupancy of a den by an adult male and an adult female black bear. As part of an ecological study of black bears in the Carson Range of the Sierra Nevada in Nevada, we entered dens in February and March 1988. On 21 February 1988 we found a four-year-old, 41-kg, transmitter-equipped female bear in the same den with an eightyear-old, 118-kg male (ages were determined by the cementum annuli technique [Stoneberg and Jonkel 1966]). Radio locations indicated that the female occupied the den all winter. There were no tracks in the snow to indicate that the male had recently entered the den, and deep snow (1-2 m) would have made travel to the den difficult after December 1987. Regardless of the date of entry by the male, follow-up radio locations indicated that the pair remained at the den site together until the end of April. The den was under a large boulder at about 2,471 m in elevation and appeared to be partially excavated. There were two entrances, one open and the other blocked by snow. The floor of the den, approximately 4 m , was covered by a large amount of brush in which each bear had a separate depression or nest 80 cm