7,498 research outputs found
Purification of 2,3,6,7,10,11-hexamethoxytriphenylene and Preparation of hexakiscarbonylmethyl and hexakiscyanomethyl derivatives of 2,3,6,7,10,11-hexahydroxytriphenylene
Exploration of an oculometer-based model of pilot workload
Potential relationships between eye behavior and pilot workload are discussed. A Honeywell Mark IIA oculometer was used to obtain the eye data in a fixed base transport aircraft simulation facility. The data were analyzed to determine those parameters of eye behavior which were related to changes in level of task difficulty of the simulated manual approach and landing on instruments. A number of trends and relationships between eye variables and pilot ratings were found. A preliminary equation was written based on the results of a stepwise linear regression. High variability in time spent on various instruments was related to differences in scanning strategy among pilots. A more detailed analysis of individual runs by individual pilots was performed to investigate the source of this variability more closely. Results indicated a high degree of intra-pilot variability in instrument scanning. No consistent workload related trends were found. Pupil diameter which had demonstrated a strong relationship to task difficulty was extensively re-exmained
Karl Löwith. Meaning in history. The theological implications of the philosophy of history Published 1949. Third impression 1955. The University of CChicago Press. 254 páginas.
Design, Fabrication and Test of Composite Curved Frames for Helicopter Fuselage Structure
Aspects of curved beam effects and their importance in designing composite frame structures are discussed. The curved beam effect induces radial flange loadings which in turn causes flange curling. This curling increases the axial flange stresses and induces transverse bending. These effects are more important in composite structures due to their general inability to redistribute stresses by general yielding, such as in metal structures. A detailed finite element analysis was conducted and used in the design of composite curved frame specimens. Five specimens were statically tested and compared with predicted and test strains. The curved frame effects must be accurately accounted for to avoid premature fracture; finite element methods can accurately predict most of the stresses and no elastic relief from curved beam effects occurred in the composite frames tested. Finite element studies are presented for comparative curved beam effects on composite and metal frames
An approach to developing the market for space shuttle payloads: Business/public policy issues and international marketing considerations
The business and public policies were assessed that were determined to be important for NASA to consider in the design of a program for stimulating use of the space transportation system (STS) among potential users in the U.S. private sector and in foreign countries, in preparation for operations of the space shuttle in the early 1980's. Salient factors related to international cooperation in space are identified for special consideration in the development of user potential of the STS
Phylogeography and Postglacial Dispersal of Smallmouth Bass (Micropterus dolomieu) into the Great Lakes
Refugia and dispersal routes of smallmouth bass (Micropterus dolomieu) into the Great Lakes were identified using 427 mitochondrial sequences from across their native range. Overall, smallmouth bass accessed the Great Lakes via long-distance dispersal from multiple refugia, and the distribution of genetic variation reflected the consequences of vicariant, dispersal, and paleogeological events. Proximity of lakes to glacial outlets had a greater predictive power on the resulting distribution of mitochondrial diversity relative to interbasin migration. Populations in the Eastern and Interior Highlands contained the most divergent and oldest haplotypes, reflecting their role as glacial refugia and subsequent high incidence of endemicity. Lake Superior, Lake Michigan, and northern Lake Huron were colonized by bass of a single mitochondrial clade that accessed the Brule–Portage (Mississippi and St. Croix rivers) and Chicago (Illinois and Fox rivers) outlets. Lakes Huron and Erie contained admixed mitochondrial lineages in part due to numerous access points, including the Fort Wayne (Wabash and Maumee rivers), Lower Peninsula of Michigan (Grand River valley), and Kirkfield (Kawartha Lakes) outlets. In contrast, populations in Lake Ontario, Georgian Bay of Lake Huron, and the St. Lawrence River were monomorphic, indicating a single but unidentified source. These patterns were consistent with many examples from the North American freshwater ichthyofauna
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