Incorporating general race and housing flexibility and deadband in rolling element bearing analysis

Methods for including the effects of general race and housing compliance and outer race-to-housing deadband (clearance) in rolling element bearing mechanics analysis is presented. It is shown that these effects can cause significant changes in bearing stiffness characteristics, which are of major importance in rotordynamic response of turbomachinery and other rotating systems. Preloading analysis is demonstrated with the finite element/contact mechanics hybrid method applied to a 45 mm angular contact ball bearing

Ceramic regenerator systems development program

The DOE/NASA Ceramic Regenerator Design and Reliability Program aims to develop ceramic regenerator cores that can be used in passenger car and industrial/truck gas turbine engines. The major cause of failure of early gas turbine regenerators was found to be chemical attack of the ceramic material. Improved materials and design concepts aimed at reducing or eliminating chemical attack were placed on durability test in Ford 707 industrial gas turbine engines late in 1974. Results of 53,065 hours of turbine engine durability testing are described. Two materials, aluminum silicate and magnesium aluminum silicate, show promise. Five aluminum silicate cores attained the durability objective of 10,000 hours at 800 C (1472 F). Another aluminum silicate core shows minimal evidence of chemical attack after 8071 hours at 982 C (1800 F). Results obtained in ceramic material screening tests, aerothermodynamic performance tests, stress analysis, cost studies, and material specifications are included

Inflammation and endothelial function: Direct vascular effects of human C-reactive protein on nitric oxide bioavailability

Background - Circulating concentrations of the sensitive inflammatory marker C-reactive protein (CRP) predict future cardiovascular events, and CRP is elevated during sepsis and inflammation, when vascular reactivity may be modulated. We therefore investigated the direct effect of CRP on vascular reactivity. Methods and Results - The effects of isolated, pure human CRP on vasoreactivity and protein expression were studied in vascular rings and cells in vitro, and effects on blood pressure were studied in rats in vivo. The temporal relationship between changes in CRP concentration and brachial flow-mediated dilation was also studied in humans after vaccination with Salmonella typhi capsular polysaccharide, a model of inflammatory endothelial dysfunction. In contrast to some previous reports, highly purified and well-characterized human CRP specifically induced hyporeactivity to phenylephrine in rings of human internal mammary artery and rat aorta that was mediated through physiological antagonism by nitric oxide (NO). CRP did not alter endothelial NO synthase protein expression but increased protein expression of GTP cyclohydrolase-1, the rate-limiting enzyme in the synthesis of tetrahydrobiopterin, the NO synthase cofactor. In the vaccine model of inflammatory endothelial dysfunction in humans, increased CRP concentration coincided with the resolution rather than the development of endothelial dysfunction, consistent with the vitro findings; however, administration of human CRP to rats had no effect on blood pressure. Conclusions - Pure human CRP has specific, direct effects on vascular function in vitro via increased NO production; however, further clarification of the effect, if any, of CRP on vascular reactivity in humans in vivo will require clinical studies using specific inhibitors of CRP. © 2005 American Heart Association, Inc

Galvanostatic Intermittent Titration Study of the Positive Electrode of a Na|Ni(Fe)-Chloride Cell

The response to open-circuit interrupts of porous mixed iron-nickel cathodes operating in NaCl-buffered, molten NaAlCl4 electrolyte has been characterized as a function of state of charge (SOC) for different iron loadings and different charge and discharge rates. After discharge, the open-circuit potential (OCP) can evolve in time from the iron plateau to the nickel plateau, and this behavior can be explained by galvanic interactions between iron metal and Ni2+. Characteristic times of the OCP transients depend on SOC and can be large. When the OCP has converged on a steady state during discharge, its value may provide an estimate of the mole fraction of NiCl2 at the interface of the triclinic (Ni,Fe)Cl2 film that resulted from metal oxidation. Detailed analyses of the experiment require modeling of the galvanic conversion rates, which depend on both charge-transfer and mass-transfer phenomena

Galvanostatic Intermittent Titration Study of the Positive Electrode of a Na|Ni(Fe)-Chloride Cell

The response to open-circuit interrupts of porous mixed iron-nickel cathodes operating in NaCl-buffered, molten NaAlCl4 electrolyte has been characterized as a function of state of charge (SOC) for different iron loadings and different charge and discharge rates. After discharge, the open-circuit potential (OCP) can evolve in time from the iron plateau to the nickel plateau, and this behavior can be explained by galvanic interactions between iron metal and Ni2+. Characteristic times of the OCP transients depend on SOC and can be large. When the OCP has converged on a steady state during discharge, its value may provide an estimate of the mole fraction of NiCl2 at the interface of the triclinic (Ni,Fe)Cl2 film that resulted from metal oxidation. Detailed analyses of the experiment require modeling of the galvanic conversion rates, which depend on both charge-transfer and mass-transfer phenomena

Embodied uncertainty: living with complexity and natural hazards

In this paper, we examine the concept of embodied uncertainty by exploring multiple dimensions of uncertainty in the context of risks associated with extreme natural hazards. We highlight a need for greater recognition, particularly by disaster management and response agencies, of uncertainty as a subjective experience for those living at risk. Embodied uncertainty is distinguished from objective uncertainty by the nature of its internalisation at the individual level, where it is subjective, felt and directly experienced. This approach provides a conceptual pathway that sharpens knowledge of the processes that shape how individuals and communities interpret and contextualise risk. The ways in which individual characteristics, social identities and lived experiences shape interpretations of risk are explored by considering embodied uncertainty in four contexts: social identities and trauma, the co-production of knowledge, institutional structures and policy and long-term lived experiences. We conclude by outlining the opportunities that this approach presents, and provide recommendations for further research on how the concept of embodied uncertainty can aid decision-making and the management of risks in the context of extreme natural hazards

Thrust tectonics, crustal thickening, hydrocarbon and ore deposits in northern Central Andes

Thanks to numerous studies realized in cooperation with Peruvian institutions, we propose for the first time in the northern Peruvian Andes a crustal-scale balanced cross-section through the entire orogen to better understand structural architecture, crustal thickening and hydrocarbon-ore deposits genesis. Abundant industrial seismic data provided by Perupetro S.A. allowed to properly constrain the geometry of the forearc and retro-foreland basins (Calderon et al., 2017; Prudhomme et al., in press). Deep crustal structures and Moho geometries are constrained by a recent teleseismic receiver function study (Condori et al., 2017). The restoration, calibrated from new geochronological data and basins analysis, highlight an intermediate stage between the Incaic (late Cretaceous-early Eocene) and Andean (Neogene) orogenies corresponding to a phase of tectonic relaxation and extension. Shortening budgets established from surface and sub-surface data in the upper crust, and from crustal thickening in the middle-lower crust, make it possible to discriminate between the importance and role of each orogeny in the mountain building. The present stage of the balanced cross-section highlights a double-verging orogen, which could result from a total amount of shortening of 180 km fairly distributed between the Incaic and Andean orogenies. Important hydrocarbon and ore deposits located along the balanced cross-section are related to the geodynamic evolution of the successive Incaic and Andean thrust systems. In the forearc (Tumbes-Salaverry) and retro-foreland (Huallaga-Marañon) basins, 2D petroleum modellings have been done using sequential restorations in order to better target exploration. In the Western and Eastern cordilleras and the Subandean zone, significant ore deposits (Cu, Pb, Zn, Au, Ag…) are concentrated in sedimentary reservoirs of Incaic and/or Andean thrust anticlines. We explore and develop an innovative hypothesis, i.e., that there are strong interactions between mineralizing fluids (of both magmatic and sedimentary origin) and petroleum systems (oil shales and reservoirs). Indeed, both ore and oil types of deposits can be found in the same basins, with similar fluid migration and storage processes in sedimentary reservoirs