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F. G. Wilson B. R. Knott C. D. Desforges 《Metallurgical and Materials Transactions A》1978,9(2):275-282
Several alloys based on Fe-25Cr-6Al and Fe-25Cr-11Al (wt pct) with additions of yttrium, Al2O3, and Y2O3 have been prepared by mechanical alloying of elemental, master alloy and oxide powders. The powders were consolidated by
extrusion at 1000°C with a reduction ratio of 36:1. The resulting oxide contents were all approximately either 3 vol pct or
8 vol pct of mixed Al2O3-Y2O3 oxides or of Al2O3. The alloys exhibited substantial ductility at 600°C: an alloy containing 3 vol pct oxide could be readily warm worked to
sheet without intermediate annealing; an 8 vol pct alloy required intermediate annealing at 1100°C. The 3 vol pct alloys could
be recrystallized to produce large elongated grains by isothermal annealing of as-extruded material at 1450°C, but the high
temperature strength properties were not improved. However, these alloys, together with some of the 8 vol pct materials, could
be more readily recrystallized after rod (or sheet) rolling; sub-stantially improved tensile and stress rupture properties
were obtained following 9 pct rod rolling at 620°C and isothermal annealing for 2 h at 1350°C. In this condition, the rup-ture
strengths of selected alloys at 1000 and 1100°C were superior to those of competitive nickel-and cobalt-base superalloys.
The oxidation resistance of all the alloys was ex-cellent.
F. G. WILSON and C. D. DESFORGES, formerly with Fulmer Re-search Institute 相似文献
636.
The cost of handling and storing materials are important elements in the total cost of inventory. Existing models do not appear to address these elements in a suitable way. This paper considers the special problem of unit handling, where the appropriate method is selected with respect to different inventory cost models. A computer program has been developed which can be used to carry out the required calculations and both the method and the computer program are illustrated by a numerical example. 相似文献
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Maxon V. Knott Laura B. Ngwenya Erika A. Correll Judy Bohnert Noah J. Ziemba Emily Allgire Tracy Hopkins Jennifer L. McGuire 《International journal of molecular sciences》2021,22(15)
Traumatic brain injury (TBI) affects over 69 million people annually worldwide, and those with pre-existing depression have worse recovery. The molecular mechanisms that may contribute to poor recovery after TBI with co-morbid depression have not been established. TBI and depression have many commonalities including volume changes, myelin disruption, changes in proliferation, and changes in glutamatergic signaling. We used a well-established animal model of depression, the Wistar Kyoto (WKY) rat, to elucidate changes after TBI that may influence the recovery trajectory. We compared the histological and molecular outcomes in the hippocampal dentate gyrus after experimental TBI using the lateral fluid percussion injury (LFPI) in the WKY and the parent Wistar (WIS) strain. We showed that WKY had exaggerated myelin loss after LFPI and baseline deficits in proliferation. In addition, we showed that while after LFPI WIS rats exhibited glutamate receptor subunit changes, namely increased GluN2B, the WKY rats failed to show such injury-related changes. These differential responses to LFPI helped to elucidate the molecular characteristics that influence poor recovery after TBI in those with pre-existing depression and may lead to targets for future therapeutic interventions. 相似文献
639.
An algorithm for converting the boundary representation of a CAD model to its octree representation 总被引:2,自引:0,他引:2
S. Anand Assistant Professor
Kenneth Knott
Professor 《Computers & Industrial Engineering》1991,21(1-4):343-347Present CAD systems store the solid model of an object using a convenient representation. Boundary models and CSG (Constructive Solid Geometry) models are the most frequently used representations. Based on recent research findings, octree representation of an object presents a promising approach in solving problems in the areas of Computer Graphics, Manufacturing and Robotics. The most notable use of octree representations is in CAD-based robotic path planning problems. Octree models have also been used in fast rendering of 3-D solid models using ray tracing methods. This paper presents an algorithm for converting the boundary representation of polyhedral models to its octree representation. Such an algorithm would provide the link between an object generated using a solid modelling system and the application involving an octree representation of an object. The algorithm is demonstrated by converting a polyhedral boundary model of a sample object to its octree representation. 相似文献
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