Comparison of Structural Concepts for Transport Aircraft with a Tail Cone Turbine

An evaluation of three structural concepts for an advanced aircraft design with a tail cone turbine is presented. Structural models were developed using an innovative rapid finite element modeling tool called Conceptual Design Shop (CDS). CDS is an attempt to fill a gap in current finite element modeling software to automatically connect wings and tails to the fuselage with sufficient support structure in airframe models. For comparison with actual aircraft structures, a model of a transport aircraft design developed using CDS is compared with published structural weight data for a Boeing 737-200. A method for computing aerodynamic stability parameters from an MSC/NASTRAN finite element analysis output deck is also discussed. Finally, the weight effects for using a tail cone turbine in an advanced transport aircraft design are evaluated by comparing three composite structural models, for which component thicknesses and cross-sections are sized by the Hypersizer software

Water-Conserving Attitudes and Landscape Choices in New Mexico

Water Conservation, Residential Landscape, Urban Water Use, Municipal Water Program, Resource /Energy Economics and Policy, Q25, Q48,

SWINE PRODUCERS ADD A MARKETING DEPARTMENT

Livestock Production/Industries, Marketing,

YIELD RESPONSE AND PRODUCTION RISK: AN ANALYSIS OF INTEGRATED PEST MANAGEMENT IN COTTON

Production uncertainty is commonly believed to be an impediment to the adoption of less pesticide-intensive methods in agriculture such as integrated pest management (IPM). To investigate the effects of pest control inputs on yields and yield variability, data from a cross-section of San Joaquin Valley cotton producers were analyzed in a heteroskedastic production model. The results suggest that yields are increasing with soil quality, crop rotation, frequency of field monitoring, and the use of independent pest control advisors. Yield variability was not found to be significantly affected by production inputs, including pesticides and IPM practices with the exception of frequent contact with extension farm advisors which was found to contribute to reduced yield variability.Production Economics, Risk and Uncertainty,

Time-delayed operation of a telerobot via geosynchronous relay

Operation of a telerobot is compromised if a time delay of more than a few hundred milliseconds exists between the operator and remote manipulator. However, the most economically attractive way to perform telerobotic functions such as assembly, maintenance, and repair in Earth orbit is via geosynchronous relay satellites to a ground-based operator. This induces loop delays from one-half to two seconds, depending on how many relays are involved. Such large delays makes direct master-slave, force-reflecting teleoperated systems infeasible. Research at JPL on a useful telerobot that operates with such time delays is described

The assessment of present, past and future climatic variability in the americas from tree-line environments

In this note we introduce one of 14 Collaborative Research Networks (CRN) funded by the Inter-American Institute for Global Change Research. It was established in 1999 and involves 15 principal investigators from 13 institutions in Canada, USA, Mexico, Bolivia, Chile and Argentina. The primary goals of the project are (i) to develop a network of tree-ring chronologies from climatically-sensitive treeline sites in the western American Cordillera and (ii) to use these data to reconstruct and compare regional interannual to decadal climate variability along the PEP-1 transect from Alaska to Tierra del Fuego. The project also seeks to enhance the development and utilization of dendrochronology for tropical mountain tree species and expand collaboration, training and the application of paleoenvironmental science within Latin America to address the issues of climate variability and change.Fil: Luckman, Brian H.. University of Western Ontario; CanadáFil: Boninsegna, Jose Armando. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin