Wind loads on a house roof

CER72-73KJD-JEC22.March 1973.Includes bibliographical references (pages 40-42).Prepared under National Bureau of Standards Contract No. NBS 273-70.Circulating copy deaccessioned 2020.The wind loads on the roof of a house were experimentally investigated by placing a 1:50 scale model house in a wind tunnel capable of generating thick, turbulent shear flows. The effects of roof geometry and wind direction were isolated by making the wind-tunnel flow representative of natural winds over very flat, open terrain. This flow simulation was accomplished by placing vortex generators at the entrance to the wind-tunnel test section. Mean pressures, root-mean-square values of the fluctuating pressures, and instantaneous peak pressures were measured at 11 preselected locations on the model's roof for 24 wind directions. A secondary purpose of the study was to determine the effects of an upwind fence on the roof pressures

Population response of triploid grass carp to declining levels of hydrilla in the Santee Cooper Reservoirs, South Carolina

Approximately 768,500 triploid grass carp ( Ctenopharyngodon idella Valenciennes) were stocked into the Santee Cooper reservoirs, South Carolina between 1989 and 1996 to control hydrilla ( Hydrilla verticillata (L.f.) Royle). Hydrilla coverage was reduced from a high of 17,272 ha during 1994 to a few ha by 1998. During 1997, 1998 and 1999, at least 98 triploid grass carp were collected yearly for population monitoring. Estimates of age, growth, and mortality, as well as population models, were used in the study to monitor triploid grass carp and predict population trends. Condition declined from that measured during a previous study in 1994. The annual mortality rate was estimated at 28% in 1997, 32% in 1998 and 39% in 1999; however, only the 1999 mortality rate was significantly different. Few (2 out of 98) of the triploid grass carp collected during 1999 were older than age 9. We expect increased mortality due to an aging population and sparse hydrilla coverage. During 1999, we estimated about 63,000 triploid grass carp system wide and project less than 3,000 fish by 2004, assuming no future stocking. management, population size Ctenopharyngodon idella, Hydrill