23,853 research outputs found
Determination of the Gyrotropic Characteristics of Hexaferrite Ceramics From 75 to 600 GHz
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Joint research into the behaviour of driven piles
Large driven piles are used widely in both onshore and offshore construction. Predicting their limiting capacities and load-displacement behaviour under a range of static and cyclic, axial, lateral and moment loading conditions is critical to many engineering applications. This paper reviews relevant recent joint research by groups at Imperial College London (ICL) and Zhejiang University China (ZJU). Two tracks of enquiry are outlined: (i) assembling and analysing a major and open database of high quality load tests conducted on industrial scale piles at well characterised sites; and (ii) modelling the effective stress regime developed around piles driven in sands. Both avenues of research are vital to enabling scientifically well-founded and yet industrially credible improvements to practical pile design methods. The scope of future joint research is also outlined
Water quality and water availability variations in an upland Galloway loch with special reference to dissolved organic matter and the distribution of benthic diatoms
Upland waters in acid sensitive regions of Scotland are vulnerable to several disturbance
processes that most importantly include atmospheric pollution and climate change as well as
to local land use. Monitoring in the Round Loch of Glenhead (RLGH) since 1988 has shown
that both water acidity and sulphate concentration have declined while the concentration of
dissolved organic matter (DOM) has steadily increased. Currently, it is unclear if increasing
DOM reflects climate change effects or relief from acid pollution. This report concerns recent
research at the RLGH on relating seasonal changes in water supply and coloured dissolved
organic matter (cDOM) to the distributions of benthic algae (diatoms). Diatoms are primarily
limited by light which in turn varies according to season, water depth and water transparency.
cDOM in lake water strongly influences water transparency and our central hypothesis is that
benthic diatom distributions are influenced by changes in cDOM concentrations and light
availability
Nonequilibrium Forces Between Neutral Atoms Mediated by a Quantum Field
We study all known and as yet unknown forces between two neutral atoms,
modeled as three dimensional harmonic oscillators, arising from mutual
influences mediated by an electromagnetic field but not from their direct
interactions. We allow as dynamical variables the center of mass motion of the
atom, its internal degrees of freedom and the quantum field treated
relativistically. We adopt the method of nonequilibrium quantum field theory
which can provide a first principle, systematic and unified description
including the intrinsic field fluctuations and induced dipole fluctuations. The
inclusion of self-consistent back-actions makes possible a fully dynamical
description of these forces valid for general atom motion. In thermal
equilibrium we recover the known forces -- London, van der Waals and
Casimir-Polder forces -- between neutral atoms in the long-time limit but also
discover the existence of two new types of interatomic forces. The first, a
`nonequilibrium force', arises when the field and atoms are not in thermal
equilibrium, and the second, which we call an `entanglement force', originates
from the correlations of the internal degrees of freedom of entangled atoms.Comment: 16 pages, 2 figure
A simultaneous confidence band for sparse longitudinal regression
Functional data analysis has received considerable recent attention and a number of successful applications have been reported. In this paper, asymptotically simultaneous confidence bands are obtained for the mean function of the functional regression model, using piecewise constant spline estimation. Simulation experiments corroborate the asymptotic theory. The confidence band procedure is illustrated by analyzing CD4 cell counts of HIV infected patients
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