Control of rotordynamic instability in a typical gas turbine's power system

The effect of rotor internal friction on the system's stability was studied when operated above the first critical speed. This internal friction is commonly caused by sliding press fits or sliding splines. Under conditions of high speed and low bearing damping, these systems will occassionally whirl at a frequency less than the shaft's rotational speed. This subsynchronous precession is a self excited phenomenon and stress reversals are created. This phenomenon was observed during engine testing. The reduction of spline friction and/or the inclusion of squeeze film damping have controlled the instability. Case history and the detail design of the squeeze film dampers is discussed

Responding to the risk of reducing resources: development of a framework for future change programmes in environmental health services

Environmental Health services in the UK have been subject to significant resource reduction over the last 5 years. It is suggested that services risk becoming unsustainable unless efficient and effective ways of working are employed. With this in mind this paper presents the findings of research into the experience of practitioners who are developing and delivering evolving Environmental Health services in English local authorities in the context of deep cutting budget reductions. The research explores the experience of change and identifies lessons learnt in the development and execution of new models of Environmental Health service delivery to mitigate against risks of unsustainable or undeliverable services. Interviews were carried out with the participants to capture their experience of change and the impact on service delivery. A range of service delivery models have been examined including outsourcing, shared services, regional delivery models and discussion of mutual arrangements and at various stages of development from planning through to full transformation. Field work was undertaken between 2014 and 2016. Thematic analysis of interview transcripts has identified six emergent themes of the experience of change: managing changes effectively; understanding the reasons for change; understanding the nature of Environmental Health; meaningful consultation; viability of the proposal; planning and timeliness. Environmental Health services undergoing transformation may benefit from taking into account the lessons learnt by organisations that have previously undergone significant change in their response to the risk of a reducing resource. Keywords: Environmental Health; austerity; regulation; emerging risk; outsourcing; managing change

Responding to the risk of reducing resource: a study of the evolution of English environmental health services

Environmental Health services in the UK have been subject to significant resource reduction over the last 3 years. It is suggested that services risk becoming unsustainable unless efficient and effective ways of working are employed. With this in mind this paper presents the findings of research into the experience of practitioners who are developing and delivering evolving environmental health services in English local authorities in the context of deep cutting budget reductions. The research aims to explore the experience of change and identify lessons learnt in the development and execution of new models of environmental health service delivery to mitigate against risks of unsustainable or undeliverable services. Participants were chosen from a range of local authority officers, managers, commissioners and leading members of the professional body who have been closely involved in the planning and delivery stages of environmental health service changes. Interviews were carried out with the participants to capture their experience of change and the impact on service delivery. A range of service delivery models have been examined including outsourcing, shared services, regional delivery models and discussion of mutual arrangements and at various stages of development from planning through to full transformation. Field work was undertaken between June 2014 and November 2015. Thematic analysis of interview transcripts has identified six emergent themes of the experience of change: managing changes effectively; understanding the reasons for change; understanding the nature of environmental health; meaningful consultation; viability of the proposal; planning and timeliness. Environmental health services undergoing transformation may benefit from taking into account the lessons learnt by organisations that have previously undergone significant change in their response to the risk of a reducing resource. The emergent themes are being developed to provide a framework of lessons learnt for environmental health services to consider when making changes to their model of service delivery

Large-scale wind-tunnel tests of descent performance of an airplane model with a tilt wing and differential propeller thrust

Wind tunnel tests of wing stall, performance, and longitudinal stability & control of large model v/stol tilt wing transport aircraf

Rotating Black Holes in Higher Dimensions with a Cosmological Constant

We present the metric for a rotating black hole with a cosmological constant and with arbitrary angular momenta in all higher dimensions. The metric is given in both Kerr-Schild and Boyer-Lindquist form. In the Euclidean-signature case, we also obtain smooth compact Einstein spaces on associated S^{D-2} bundles over S^2, infinitely many for each odd D\ge 5. Applications to string theory and M-theory are indicated.Comment: 8 pages, Latex. Short version, with more compact notation, of hep-th/0404008. To appear in Phys. Rev. Let

Opaque or transparent? A link between neutrino optical depths and the characteristic duration of short gamma-ray bursts

Cosmological gamma ray bursts (GRBs) are thought to occur from violent hypercritical accretion onto stellar mass black holes, either following core collapse in massive stars or compact binary mergers. This dichotomy may be reflected in the two classes of bursts having different durations. Dynamical calculations of the evolution of these systems are essential if one is to establish characteristic, relevant timescales. We show here for the first time the result of dynamical simulations, lasting approximately one second, of post--merger accretion disks around black holes, using a realistic equation of state and considering neutrino emission processes. We find that the inclusion of neutrino optical depth effects produces important qualitative temporal and spatial transitions in the evolution and structure of the disk, which may directly reflect upon the duration and variability of short GRBs.Comment: Accepted for publication in ApJ Letter

Information Flow in Entangled Quantum Systems

All information in quantum systems is, notwithstanding Bell's theorem, localised. Measuring or otherwise interacting with a quantum system S has no effect on distant systems from which S is dynamically isolated, even if they are entangled with S. Using the Heisenberg picture to analyse quantum information processing makes this locality explicit, and reveals that under some circumstances (in particular, in Einstein-Podolski-Rosen experiments and in quantum teleportation) quantum information is transmitted through 'classical' (i.e. decoherent) information channels.Comment: PostScript version now available: http://www.qubit.org/people/patrickh/Papers/InformationFlow.p