Wake dynamics and rotor-fuselage aerodynamic interactions

The unsteady loads experienced by a helicopter are known to be strongly influenced by aerodynamic interactions between the rotor and fuselage; these unsteady loads can lead to deficiencies in handling qualities and unacceptable vibratory characteristics of the rotorcraft. This work uses a vorticity-based computational model to study the governing processes that underpin this aerodynamic interaction and aims to provide greater understanding of the wake dynamics in the presence of a fuselage, as well as an appreciation of how the geometry of the wake affects the loading on the fuselage. The well-known experiments using NASA's ROBIN fuselage are used to assess the accuracy of the computations. Comparisons of calculations against results from smoke visualization experiments are used to demonstrate the ability of the model to reproduce accurately the geometry of the rotor wake, and comparisons with inflow data from the experiments show the method to capture well the velocity field near to the rotor. The fuselage model is able to predict accurately the unsteady fuselage loading that is induced by blade passage and also by the inviscid interaction between the main rotor wake and fuselage

Intrinsic parameter fluctuations in decananometer MOSFETs introduced by gate line edge roughness

In this paper, we use statistical three-dimensional (3-D) simulations to study the impact of the gate line edge roughness (LER) on the intrinsic parameters fluctuations in deep decananometer (sub 50 nm) gate MOSFETs. The line edge roughness is introduced using a Fourier synthesis technique based on the power spectrum of a Gaussian autocorrelation function. In carefully designed simulation experiments, we investigate the impact of the rms amplitude /spl Delta/ and the correlation length /spl Lambda/ on the intrinsic parameter fluctuations in well scaled, but simple devices with fixed geometry as well as the channel length and width dependence of the fluctuations at fixed LER parameters. For the first time, we superimpose in the simulations LER and random discrete dopants and investigate their relative contribution to the intrinsic parameter fluctuations in the investigated devices. For particular MOSFET geometries, we were able to identify the regions where each of these two sources of intrinsic parameter fluctuations dominates

Intrinsic fluctuations in sub 10-nm double-gate MOSFETs introduced by discreteness of charge and matter

We study, using numerical simulation, the intrinsic parameter fluctuations in sub 10 nm gate length double gate MOSFETs introduced by discreteness of charge and atomicity of matter. The employed "atomistic" drift-diffusion simulation approach includes quantum corrections based on the density gradient formalism. The quantum confinement and source-to-drain tunnelling effects are carefully calibrated in respect of self-consistent Poisson-Schrodinger and nonequilibrium Green's function simulations. Various sources of intrinsic parameter fluctuations, including random discrete dopants in the source/drain regions, single dopant or charged defect state in the channel region and gate line edge roughness, are studied in detail

Going the same 'weigh': spousal correlations in obesity in the UK

The obesity epidemic has received widespread media and research attention. However, the social phenomenon of obesity is still not well understood. Data from the 2004 and 2006 waves of the British Household Panel Survey (BHPS) show positive and significant correlations in spousal body mass index (BMI). This paper explores three mechanisms of shared individual characteristics, social influence and shared environment to explain this correlation. A number of econometric specifications are used to investigate the role of observed individual characteristics, own health, spouse health, social influence, contextual effects and unobserved individual effects on the influence of these three hypotheses on the correlation in spousal BMI. Results indicate that social influence and shared individual characteristics, which may arise through assortative matching, both contribute to correlation in spousal BMI

Out-of-pocket health care expenditure in Turkey: analysis of the household budget surveys 2002-2008

This paper analyses the prevalence of ‘catastrophic’ out-of-pocket health expenditure in Turkey and identifies the factors which are associated with its risk using the Turkish Household Budget Surveys from 2002 to 2008. A sample selection approach based on Sartori (2003) is adopted to allow for the potential selection problem which may arise if poor households choose not to seek health care due to concerns regarding its affordability. The results suggest that poor households are less likely to seek health care as compared to non-poor households and that a negative relationship between poverty and experiencing catastrophic health expenditure remains even after allowing for such selection bias. Our findings, which may assist policy-makers concerned with health care system reforms, also highlight factors such as insurance coverage, which may protect households from the risk of incurring catastrophic health expenditure

Strategic Behaviour of Firms in a Duopoly and the Impact of Extending the Patenting Period

This paper deals with strategic behaviour of firms in a duopoly, subsequent to the claim by one firm that it has reduced the unit cost of production. A variety of possible strategic equilibria are discussed in the context of a duopoly game between a multinational and a local firm. In the context of an extended uniform period of patenting, as finally agreed in the Uruguay round (1994), firms have increased incentive to take patents. In the presence of cost differences, the act of taking process-patents has implications for the equilibrium output strategies of the duopoly firms and sometimes may have a negative overall welfare effect for the local producer and consumers

Parallel semiconductor device simulation: from power to 'atomistic' devices

This paper discusses various aspects of the parallel simulation of semiconductor devices on mesh connected MIMD platforms with distributed memory and a message passing programming paradigm. We describe the spatial domain decomposition approach adopted in the simulation of various devices, the generation of structured topologically rectangular 2D and 3D finite element grids and the optimisation of their partitioning using simulated annealing techniques. The development of efficient and scalable parallel solvers is a central issue of parallel simulations and the design of parallel SOR, conjugate gradient and multigrid solvers is discussed. The domain decomposition approach is illustrated in examples ranging from `atomistic' simulation of decanano MOSFETs to simulation of power IGBTs rated for 1000 V

A geochemical drainage survey of the Fleet granitic complex and its environs

A regional geochemical drainage reconnaissance programme was undertaken over 900 km2 of south-west Scotland centred on the Fleet granitic complex. Rocks of Ordovician and Silurian age outcrop over the area, into which have been intruded the Fleet and Loch Doon plutons. Multi-element analysis of stream sediments and heavy mineral concentrates shows a number of patterns of trace element distribution related to different lithologies and to mineralisation. Broad scale patterns exhibited by some elements denote compositional variations within the Lower Palaeozoic sediments and within the Fleet and Loch Doon plutons. On thebasis of the drainage data the sedimentary rocks have been divided into eight distinct geochemical units each characterised by different element distribution patterns. The Fleet and Loch Doon plutons have been sub-divided on the same basis. Follow-up investigations of drainage anomalies led to the discovery of both structure-controlled and disseminated base metal mineralisation in the Penkiln drainage basin within the salthernaureole of the Loch Doon granite. The distribution of Cu, F’b and Zn to the south and south-west of the Fleet granite suggests a zonation of vein minerahsation, with Cu prominent adjacent to the granite contact and F’b and Zn having a wider dispersion away from the granite. Other anomalies delineate a mineralised lineament that follows the regional strike of the Lower Palaeozoic sediments, southeast of the Fleet granite

"Metal for the masses": or, will metal ever be mainstream again? (and why we should want it to be…)

Exploring the model of scene-based innovation and scarcity that characterised the 90s extreme metal underground, as eloquently outlined by Keith Kahn-Harris, this paper seeks to evaluate the extent to which its model of “eclipsed” symbolic capital accumulation is the key not to its success but relative failure to achieve innovation, development and change in metal music. Debating Lena and Peterson’s AgSIT model of genre trajectories, this paper argues such change in metal music have always been tied to the formation and demise of music “mainstreams.” The problem from this perspective is that NWOBHM, doom, power (including symphonic), thrash, grindcore, death and black metal did not mainstream enough (with the exception of some notable bands) to allow the next cycle of musical innovation to commence