Aircraft development programmes generally involve collaboration in engineering between different organisations, in order to develop innovative products efficiently, to involve necessary skills from the supply chain, and to spread risks and costs among the partners. The size and complexity of the programmes, the market demands and the contexts of competition all require the collaboration to be effective and efficient. Advances in information technology provide new capabilities to support collaborative design but a step change is needed to harness and coordinate this support to be effective and efficient. The extended enterprises in which the collaborative engineering activities take place span the partner organisations. Engineers wishing to cooperate are however facing security constraints. For example, technical security measures such as firewalls and proxy servers hamper smooth exchange of engineering data and seamless execution of collaborative workflows. The restrictions assist organisations in protecting their assets and in remaining compliant with legislation and regulations. From a programme technical point of view, effective and efficient collaboration in this world full of security and the resulting connectivity constraints is a major challenge. This paper describes the usefulness, necessity and challenges of collaboration between multi-disciplinary specialists in aerospace engineering. It presents the ‘Brics’ technology that supports the realisation of cross-organisation collaborative workflows. The technology supports aircraft manufacturers and their supply chains in facing the challenges and in performing analyses of innovative aircraft designs collaboratively. This technology has emerged from past research projects, and has been further developed and successfully demonstrated in the Thermal Overall Integrated Conception of Aircraft project, a research and technology development project carried out in the Seventh Framework Programme funded by the European Union. The developed technology is illustrated in the context of a multi-partner analysis and optimisation study, which has been conducted as part of a pylon design that is subject to thermal constraints.
Classical Cepheids are essential objects in the study of stellar evolution and cosmology; however, we know little about their magnetic properties. We report the detection of Stokes V features interpreted as Zeeman signatures in four classical Cepheids using high-resolution spectropolarimetric observations obtained with ESPaDOnS at the Canada–France–Hawaii Telescope. Eight observations of η Aql were acquired in 2017 covering its 7.2 d pulsation period, and single observations of Polaris, ζ Gem, δ Cep, and RT Aur were obtained in 2020 as part of our ongoing systematic survey. We use mean circular polarization Stokes V profiles generated using the least-squares deconvolution procedure to diagnose Zeeman signatures and measure mean longitudinal field strengths 〈Bz〉. We detect magnetic signatures across all pulsation phases of η Aql (−0.89 ± 0.47 G$\, \lt \langle B_{z}\rangle \lt 1.27\pm 0.40$ G), as well as in the single observations of Polaris (0.59 ± 0.16 G), ζ Gem (0.41 ± 0.16 G), and δ Cep (0.43 ± 0.19 G). The Stokes V profile of Polaris is detected at extremely high signal-to-noise ratio and implies a complex magnetic field topology. It stands in stark contrast to all other detected Stokes V profiles, which show unusual approximately unipolar positive circular polarization lobes analogous to those observed in some Am stars.
Vinyl chloroformate (1) reacts with silver acetate in chlorobenzene at 60°to give 17% vinyl acetate (2) and 65% divinyl carbonate (3). Under the same conditions 1 reacts with silver trifluoroacetate to give 77% vinyl trifluoroacetate (4). The latter reaction is shown on the basis of 180 labeling to proceed with retention of the carbon-oxygen bond and is considered to involve a carbonate intermediate. In the presence of tetramethylurea, vinyl chloroformate reacts with silver hexafluoroantimonate in chlorobenzene to give 0-(carboxyvinyl )tetramethyluronium hexafluoroantimonate (7) in 80% yield. The reaction of phenyl chloroformate with silver hexafluoroantimonate in chlorobenzene at 100°in the presence of tetramethylurea to give phenyl N,N-dimethyl carbamate is suggested to involve a uronium salt 9 similar to 7. The oxime chloroformates of benzophenone, fluorenone, and syn-and oníf-4-methylbenzophenone react with silver tetrafluoroborate to give amides by the normal Beckmann rearrangement. Cationic intermediates with sp-sp8-hybridized carbon and nitrogen do not appear to be involved in these reactions.
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