Propulsion system study for Small Transport Aircraft Technology (STAT)

Propulsion system technologies applicable to the generation of commuter airline aircraft expected to enter service in the 1990's are identified and evaluated in terms of their impact on aircraft operating economics and fuel consumption. The most promising technologies in the areas of engine, propeller, gearbox, and nacelle design are recommended for future research. Each item under consideration is evaluated relative to a modern baseline engine, the General Electric CT7-5, in a current technology aircraft flying a fixed range and payload. The analysis is presented for two aircraft sizes (30 and 50 passenger), over a range of mission lengths (100 to 1100 km) and fuel costs ($264 to$396 per cu m)

Wind tunnel balance

A flow-through balance is provided which includes a non-metric portion and a metric portion which form a fluid-conducting passage in fluid communication with an internal bore in the sting. The non-metric and metric portions of the balance are integrally connected together by a plurality of flexure beams such that the non-metric portion, the metric portion and the flexure beams form a one-piece construction which eliminates mechanical hysteresis between the non-metric and the metric portion. The system includes structures for preventing the effects of temperature, pressure and pressurized fluid from producing asymmetric loads on the flexure beams. A temperature sensor and a pressure sensor are located within the fluid-conducting passage of the balance. The system includes a longitudinal bellows member connected at two ends to one of the non-metric portion and the metric portion and at an intermediate portion thereof to the other of (1) and (2). A plurality of strain gages are mounted on the flexure beams to measure strain forces on the flexure beams. The flexure beams are disposed so as to enable symmetric forces on the flexure beams to cancel out so that only asymmetric forces are measured as deviations by the strain gages

Shorebird Breeding Biology in Wetlands of the Playa Lakes, Texas, USA

Wetlands in the Playa Lakes Region of Texas are important habitats for North American wintering waterfowl and migrant shorebirds. However, shorebird breeding biology has been overlooked in characterizing the region’s ecological importance. In 1998 and 1999, American Avocet (Recurvirostra americana), Black-necked Stilt ( Himantopus mexicanus ), Killdeer (Charadrius vociferous), and Snowy Plover (C. alexandrinus) breeding ecology were studied in playas, saline lakes, and riparian wetlands in the Playa Lakes Region of Texas. Chronology of nest initiation, clutch sizes, and hatching success for 298 Snowy Plover, 111 American Avocet, 43 Killdeer, and 26 Blacknecked Stilt clutches were measured. All four species nested in saline lakes, American Avocet and Killdeer also nested in playas, and Snowy Plover nested on riparian wetlands. American Avocet had higher hatching success in 1999 (52%) than 1998 (8%), because of more suitable hydrological conditions and lower predation. Hatching success was higher in 1998 than 1999 for Killdeer (1998, 63%; 1999, 21%) and Snowy Plover (1998, 47%; 1999, 33%) due to failures caused by flooding and hail in 1999. In other regions, clutch predation limits shorebird productivity, but hatching success in the Playa Lakes Region appears to be limited by unpredictable precipitation patterns and wetland hydroperiod. As such, breeding shorebird conservation and management should focus upon maintaining wetland hydrological integrity

Management Systems in Secondary Reading Classrooms

One outcome of federal, state or district funding of reading programs has been the development of a competency based curriculum with the inclusion of a classroom management system. This management system is the structure for the implementation of the goals, guidelines and behavioral objectives of the program. Each program with its management system is developed and written by teachers In consultation with school and/or district level cooperation

Shorebird Habitat Use and Nest-site Selection in the Playa Lakes Region

Wetlands in the Playa Lakes Region (PLR) provide important habitats for wintering waterfowl, cranes, and both migrant and breeding shorebirds. Playa Lakes Region wetlands experience naturally fluctuating hydroperiods but are exposed to anthropogenic stresses, which are exacerbated during summer and may influence PLR wetland occupancy and selection by breeding shorebirds. We examined wetland-scale habitat use and nest-site selection of the 4 dominant shorebirds (American avocets [Recurvirostra americana], black-necked stilts [Himantopus mexicanus], killdeer [Charadrius vociferus], snowy plovers [C. alexandrinus]) nesting in playas, saline lakes, and in both created and riparian wetlands in the PLR of Texas, USA. All 4 species nested in saline lakes. Only avocets and kill deer nested in playas, and snowy plovers nested in riparian wetlands. No nests were found in created wetlands. Wetland habitat changed (P \u3c 0.001) during the breeding season, while water habitats generally decreased. Used (i.e., shorebirds found nesting) wetlands had more (P \u3c 0.05) mudflats than non-used (i.e., shorebirds not found nesting) wetlands, which had more (P \u3c 0.05) dry habitats. Used and non-used wetlands had similar (P \u3e 0.05) amounts of water habitats. Nests were located close to vegetation on bare dry ground and dry ground with vegetation. Because water is ephemeral in PLR wetlands, shorebirds must select—in a somewhat predictive manner upon arrival—wetlands with suitable nest-site and brood-rearing habitat. Although surface water is necessary for nesting, its presence is not adequate for delineating suitable PLR wetland habitat for breeding shorebirds. Our findings that created wetlands cannot compensate for regional wetland losses in habitat or function highlights the need for conservation of natural PLR wetlands

Breeding Biology of an Interior Least Tern (Sterna Antillarum Athalassos) Colony in Childress County of North Texas

This study documented nest success, nest initiation chronology and nest site selection for interior least terns (Sterna antillarum athalassos) along the Prairie Dog Town Fork of the Red River in Childress County, Texas during 1998. Terns experienced a 65% nest success rate (Mayfield estimate 71 %) and clutch sizes ranged from 1 3 eggs (x = 2.25) for 20 nests. Seventy percent of all nests were initiated during the first 20 days of June, which coincided with the highest number of adult terns observed on the study site. All nests were found on gravel/sand bars in the river basin; 25% were placed on gravel and 75% were placed on sand. Sixty-five percent of tern nests were located within 15 cm of driftwood and/or rocks, but nests were not more frequently associated with objects than random sites (P \u3e 0.05). Nests were generally \u3e 10 m from vegetative cover and 200 m from surface water. However, habitat variables (i.e., distances to upland, mudflat, water and vegetative cover) did not vary (P \u3e 0.05) between nests and random sites nor between successful and nonsuccessful nests. This colony of interior least terns was last documented in the mid-1980s and evidently has some degree of stability. Conservation efforts should focus on protecting, restoring and enhancing riparian wetland habitats in the High and Rolling Plains of Texas for this endangered species

Model of real-time automation and control systems for combined sewers

CER72-73WB-CBW-GLS41.Includes bibliographical references (page 79).Supported by OWRR grant number 14-31-0001-3410, project no. C-2207 from funds provided by the U.S. Dept. of Interior as authorized under the Water Resources Act of 1964, Public Law 88-379, as amended.Supported by OWRR grant number 14-31-0001-3410, project no. C-2207