8,686 research outputs found
A piecewise exponential model for three-dimensional analysis of sandwich panels with arbitrarily graded core
Open Access funded by Engineering and Physical Sciences Research Council Acknowledgements Financial support of this research by the EPSRC (Engineering and Physical Sciences Research Council) (EP/P503299/1, EP/P503930/1), United Kingdom, is gratefully acknowledged.Peer reviewedPublisher PD
Performance of functionally graded plates under localised transverse loading
AbstractThis paper presents a study of the bending of an isotropic functionally graded plate under localised transverse load through a combination of analytical and computational means. The analytical modelling is based on the recently developed three-dimensional elasticity solution, expanded to cover different loading types, whilst the Finite Element model uses graded isoparametric elements. The plate under consideration is assumed to be simply supported, with Youngās and shear moduli varying exponentially through the thickness and the Poissonās ratio constant. Comparative analysis of stress and displacement fields in functionally graded and homogeneous plates subjected to uniformly distributed and patch loadings is carried out
Three-dimensional elasticity analysis of sandwich panels with functionally graded transversely isotropic core
Open Access via Springer Compact Agreement. Financial support of this research by the EPSRC DTA is gratefully acknowledgedPeer reviewedPublisher PD
Impact of single nucleotide polymorphisms in leptin, leptin receptor, growth hormone receptor, and diacylglycerol acyltransferase (DGAT1) gene loci on milk production, feed, and body energy traits of UK dairy cows
Three-dimensional elastic deformation of functionally graded isotropic plates under point loading
Acknowledgement Financial support of this research by The Royal Society (UK) under grant number JP090633 is gratefully acknowledged.Peer reviewedPostprin
A Proposed Method for Monitoring U.S. Population Health: Linking Symptoms, Impairments, and Health Ratings
We propose a method of quantifying non-fatal health on a 0-1 QALY scale that details the impact of specific symptoms and impairments and is not based on ratings of counterfactual scenarios. Measures of general health status are regressed on health impairments and symptoms in different domains, using ordered probit and ordinary least squares regression. This yields estimates of their effects analogous to disutility weights, and accounts for complex non-additive relationships. Health measures used include self-rated health status on a 5-point scale, EuroQol 5D (EQ-5D) scores, and ratings of current health using a 0-100 rating scale and a time-tradeoff. Data are from the nationally representative Medical Expenditure Panel Survey (MEPS) year 2002 (N=34,615), with validation in an independent sample from MEPS 2000 (N=21,067) and among 1420 adults age 45-89 in the Beaver Dam Health Outcomes Study. Decrement weights for symptoms and impairments are used to derive estimates of overall health-related quality of life, laying the groundwork for a detailed national summary measure of health. To purchase a copy of the earlier version of this paper, please contact the Working Papers department directly at (617) 588 1405.
Convectiveāreactive nucleosynthesis of K, Sc, Cl and p-process isotopes in OāC shell mergers
Ā© 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. We address the deficiency of odd-Z elements P, Cl, K and Sc in Galactic chemical evolution models through an investigation of the nucleosynthesis of interacting convective O and C shells in massive stars. 3D hydrodynamic simulations of O-shell convection with moderate C-ingestion rates show no dramatic deviation from spherical symmetry. We derive a spherically averaged diffusion coefficient for 1D nucleosynthesis simulations, which show that such convective-reactive ingestion events can be a production site for P, Cl, K and Sc. An entrainment rate of 10-3Mās-1features overproduction factors OPsā 7. Full O-C shell mergers in our 1D stellar evolution massive star models have overproduction factors OPm> 1 dex but for such cases 3D hydrodynamic simulations suggest deviations from spherical symmetry. Ī³ - process species can be produced with overproduction factors of OPm> 1 dex, for example, for130, 132Ba. Using the uncertain prediction of the 15Mā, Z = 0.02 massive star model (OPmā 15) as representative for merger or entrainment convective-reactive events involving O- and C-burning shells, and assume that such events occur in more than 50 per cent of all stars, our chemical evolution models reproduce the observed Galactic trends of the odd-Z elements
Laser-like X-ray Sources Based on Optical Reflection from Relativistic Electron Mirror
A novel scheme is proposed to generate uniform relativistic electron layers
for coherent Thomson backscattering. A few-cycle laser pulse is used to produce
the electron layer from an ultra-thin solid foil. The key element of the new
scheme is an additional foil that reflects the drive laser pulse, but lets the
electrons pass almost unperturbed. It is shown by analytic theory and by 2D-PIC
simulation that the electrons, after interacting with both drive and reflected
laser pulse, form a very uniform flyer freely cruising with high relativistic
gamma-factor exactly in drive laser direction (no transverse momentum). It
backscatters probe light with a full Doppler shift factor of 4*gamma^2. The
reflectivity and its decay due to layer expansion is discussed.Comment: 5 pages, 3 figures, submitted, invited talk on the workshop of
Frontiers in Intense Laser-Matter Interaction Theory, MPQ, March 1-3, 2010
Octahedral Tilt Instability of ReO_3-type Crystals
The octahedron tilt transitions of ABX_3 perovskite-structure materials lead
to an anti-polar (or antiferroelectric) arrangement of dipoles, with the low
temperature structure having six sublattices polarized along various
crystallographic directions. It is shown that an important mechanism driving
the transition is long range dipole-dipole forces acting on both displacive and
induced parts of the anion dipole. This acts in concert with short range
repulsion, allowing a gain of electrostatic (Madelung) energy, both
dipole-dipole and charge-charge, because the unit cell shrinks when the hard
ionic spheres of the rigid octahedron tilt out of linear alignment.Comment: 4 page with 3 figures included; new version updates references and
clarifies the argument
Study of the volume and spin collapse in orthoferrite LuFeO_3 using LDA+U
Rare earth (R) orthoferrites RFeO_3 exhibit large volume transitions
associated with a spin collapse. We present here ab initio calculations on
LuFeO_3. We show that taking into account the strong correlation among the
Fe-3d electrons is necessary. Indeed, with the LDA+U method in the Projector
Augmented Wave (PAW), we are able to describe the isostructural phase
transition at 50 GPa, as well as a volume discontinuity of 6.0% at the
transition and the considerable reduction of the magnetic moment on the Fe
ions. We further investigate the effect of the variation of U and J and find a
linear dependence of the transition pressure on these parameters. We give an
interpretation for the non-intuitive effect of J. This emphasizes the need for
a correct determination of these parameters especially when the LDA+U is
applied to systems (e.g in geophysical investigations) where the transition
pressure is a priori unknown
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