Investigation of refracting flows for acoustic suppression

An experimental investigation to determine the possibility of using refracting flows for the suppression of aircraft inlet noise is described. Observations of wave refraction in duct flows and measurements of the increase in effectiveness of acoustic linings due to refraction have suggested methods for the design of engine inlet ducts which can either suppress noise internally or direct it to where it causes less annoyance

Inuit Seal Hunting in Canada: Emerging Narratives in an Old Controversy

Seal hunting in Canada is a historically controversial topic. Animal rights groups have campaigned that Atlantic Canadians inhumanely slaughter thousands of “baby” seals every year. The work of these animal rights groups has led to changes in national fisheries regulations and markets. The market changes have greatly affected the livelihoods of many Atlantic Canadians, but even more so of the Inuit who also hunt seals in Canada’s Arctic regions. Animal rights groups largely excluded and ignored the Inuit who depended on the larger Atlantic Canadian seal market. However, Inuit have recently mobilized though social media to reclaim the narrative surrounding seal hunting. Their campaign has helped change national policy. The Government of Canada has since created a scheme to increase market access to Inuit-harvested seals. Yet, little information is available for this scheme and its effectiveness needs to be further investigated.Au Canada, la chasse au phoque est un sujet qui porte à controverse depuis fort longtemps. Des groupes de défense des animaux ont mené une campagne soutenant que les Canadiens de la région atlantique massacrent inhumainement des milliers de « bébés » phoques chaque année. Le travail de ces groupes de défense des droits des animaux a mené à des modifications à la réglementation et aux marchés de la pêche au niveau national. L’évolution du marché a eu une grande incidence sur les moyens de subsistance de nombreux Canadiens de la région de l’Atlantique, mais encore plus sur les Inuits qui chassent également le phoque dans les régions arctiques du Canada. Les groupes de défense des animaux ne se sont à peu près pas préoccupés des Inuits qui dépendaient du marché canadien du phoque de la région atlantique dans son ensemble. Cependant, les Inuits se sont mobilisés récemment par l’intermédiaire des médias sociaux pour récupérer le récit entourant la chasse au phoque. Leur campagne a favorisé la modification de la politique nationale. Depuis, le gouvernement du Canada a créé un mécanisme visant à accroître l’accès au marché des phoques capturés par les Inuits. Cependant, il existe peu de renseignements au sujet de ce programme et son efficacité doit être examinée de plus près

Mission design for a ballistic slow flyby Comet Encke 1980

Preliminary mission analyses for a proposed 1980 slow flyby (7-9 km/s) of comet Encke are presented. Among the topics covered are science objectives, Encke's physical activity and ephemeris accuracy, trajectory and launch-window analysis, terminal guidance, and spacecraft concepts. The nominal mission plan calls for a near-perihelion intercept with two spacecraft launched on a single launch vehicle. Both spacecraft will arrive at the same time, one passing within 500 km from Encke's nucleus on its sunward side, the other cutting through the tail region. By applying a small propulsive correction about three weeks after the encounter, it is possible to retarget both spacecraft for a second Encke intercept in 1984. The potential science return from the ballistic slow flyby is compared with other proposed mission modes for the 1980 Encke flyby mission, including the widely advocated slow flyby using solar-electric propulsion. It is shown that the ballistic slow flyby is superior in every respect

Liquid rocket engine axial-flow turbopumps

The axial pump is considered in terms of the total turbopump assembly. Stage hydrodynamic design, pump rotor assembly, pump materials for liquid hydrogen applications, and safety factors as utilized in state of the art pumps are among the topics discussed. Axial pump applications are included

Changes in New Zealand pan evaporation since the 1970s,

ABSTRACT Several previous studies have reported declines in pan evaporation rate throughout the Northern Hemisphere of about 2-4 mm a −2 for various periods since the 1950s. A recent analysis of Australian pan evaporation reported a similar decline and raises the possibility that part of the phenomenon may be related to the greenhouse effect. To assess that possibility, one needs to know whether the decline in evaporative demand is happening in other parts of the Southern Hemisphere. As a first step to addressing the latter question, we examined the trend in pan evaporation at 19 New Zealand sites. We found statistically significant declines in pan evaporation rate at 6 of the 19 sites. There were no sites with statistically significant increases in pan evaporation. When averaged across all 19 sites, the decline in pan evaporation rate was roughly 2 mm a −2 (i.e. mm per annum per annum) since the 1970s. Over a 30-year period, this is equivalent to a decline of about 60 mm a −1 in annual pan evaporation. These results are generally consistent with those reported throughout the Northern Hemisphere and in Australia. We conclude that the trend for decreasing evaporative demand previously reported throughout the Northern Hemisphere terrestrial surface may also be widespread in the Southern Hemisphere. This may be, in part, a greenhouse-related phenomenon