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

Fragmentation dynamics of the ethyl bromide and ethyl iodide cations: a velocity-map imaging study

The photodissociation dynamics of ethyl bromide and ethyl iodide cations (C2H5Br+ and C2H5I+) have been studied. Ethyl halide cations were formed through vacuum ultraviolet (VUV) photoionization of the respective neutral parent molecules at 118.2 nm, and were photolysed at a number of ultraviolet (UV) photolysis wavelengths, including 355 nm and wavelengths in the range from 236 to 266 nm. Time-of-flight mass spectra and velocity-map images have been acquired for all fragment ions and for ground (Br) and spin–orbit excited (Br*) bromine atom products, allowing multiple fragmentation pathways to be investigated. The experimental studies are complemented by spin–orbit resolved ab initio calculations of cuts through the potential energy surfaces (along the RC–Br/I stretch coordinate) for the ground and first few excited states of the respective cations. Analysis of the velocity-map images indicates that photoexcited C2H5Br+ cations undergo prompt C–Br bond fission to form predominantly C2H5+ + Br* products with a near-limiting ‘parallel’ recoil velocity distribution. The observed C2H3+ + H2 + Br product channel is thought to arise via unimolecular decay of highly internally excited C2H5+ products formed following radiationless transfer from the initial excited state populated by photon absorption. Broadly similar behaviour is observed in the case of C2H5I+, along with an additional energetically accessible C–I bond fission channel to form C2H5 + I+ products. HX (X = Br, I) elimination from the highly internally excited C2H5X+ cation is deemed the most probable route to forming the C2H4+ fragment ions observed from both cations. Finally, both ethyl halide cations also show evidence of a minor C–C bond fission process to form CH2X+ + CH3 products

On the variability of I(7620 Å)/I(5577 Å) in low altitude aurora

International audienceAn auroral electron excitation model, combined with simple equilibrium neutral and ion chemistry models, is used to investigate the optical emission processes and height profiles of I(5577 Å) and I(7620 Å) in the 90 to 100 km altitude region. It is shown that the apparent discrepancies between ground-based and rocket-borne auroral observations of the I(7620 Å)/I(5577 Å) ratio are due to the extreme height variation of this intensity ratio in the 90 to 100 km region

Testing a Grassroots Citizen Science Venture Using Open Design, “the Bee Lab Project”

The Bee Lab project applies Citizen Science and Open Design to beekeeping, enabling participants to construct monitoring devices gathering reciprocal data, motivating participants and third parties. The presented approach uses design workshops to provide insight into the design of kits, user motivations, promoting reciprocal interests and address community problems. This paper signposts issues and opportunities in the process of designing Citizen Science tools for communities using Open Design to solve individual problems, including: downloadable design for social/local change, laypeople creating technology and repairable kits

Building the foundations of collaboration: From housing development to community renewal

While collaborative governance and planning are seen as an improvement on technocratic “top-down” approaches, they are often criticized for exacerbating power imbalances, failing to be inclusive and/or impartial, and for ignoring historical conflict. This paper aims to investigate how strong foundations for collaborative housing renewal may be built so as to facilitate broader community renewal ambitions. Using qualitative methods and based on two case studies of housing renewal projects in communities described as “deprived”, we found the informal but foundational phase was critical in mitigating contextual and historical factors that had often led to marginalization during more formal negotiations. The foundations for the housing renewal work involved building trust and credibility, collective community capability, a “grounded” agenda and a mandate. We argue that these foundations should not be seen as informal and therefore optional; rather they fundamentally shape formal processes of collaboration and can be used to address tensions between participative and representative democracy

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