Department of Materials Science and Metallurgy: Recent submissions
Now showing items 201-220 of 648
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Uniqueness of the Kerr-de Sitter spacetime as an algebraically special solution in five dimensions
(SpringerCommunications in Mathematical Physics, 2015-08-20)We determine the most general solution of the five-dimensional vacuum Einstein equation, allowing for a cosmological constant, with (i) a Weyl tensor that is type II or more special in the classification of Coley et al., ...
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The structure and stability of vortices in astrophysical discs
(University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2015-10-06)This thesis finds that vortex instabilities are not necessarily a barrier to their potential as sites for planetesimal formation. It is challenging to build planetesimals from dust within the lifetime of a protoplanetary disc ...
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On the meaning of mixing efficiency for buoyancy driven mixing in stratified turbulent flows
(Cambridge University PressJournal of Fluid Mechanics, 2015-09-17)The concept of a mixing efficiency is widely used to relate the amount of irreversible diabatic mixing in a stratified flow to the amount of energy available to support mixing. This common measure of mixing in a flow is ...
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A multi-timescale analysis of phase transitions in precessing black-hole binaries
(APSPhysical Review D, 2015-09-14)The dynamics of precessing binary black holes (BBHs) in the post-Newtonian regime has a strong timescale hierarchy: the orbital timescale is very short compared to the spin-precession timescale which, in turn, is much ...
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On the initial value problem in general relativity and wave propagation in black-hole spacetimes
(University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2014-11-11)The first part of this thesis is concerned with the question of global uniqueness of solutions to the initial value problem in general relativity. In 1969, Choquet-Bruhat and Geroch proved, that in the class of globally ...
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Inclined gravity currents filling basins: The influence of Reynolds number on entrainment into gravity currents
(AIPPhysics of Fluids, 2015-09-17)Gravity currents of dense fluid feed basins in many important natural and industrial systems, such as lakes fed by dense rivers and auditoria supplied with cooled air by ventilation systems. The entrainment into these ...
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Geometric capture and escape of a microswimmer colliding with an obstacle
(Royal Society of ChemistrySoft Matter, 2015-03-09)Motivated by recent experiments, we consider the hydrodynamic capture of a microswimmer near a stationary spherical obstacle. Simulations of model equations show that a swimmer approaching a small spherical colloid is ...
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Geometric pumping in autophoretic channels
(Royal Society of ChemistrySoft Matter, 2015-05-07)Many microfluidic devices use macroscopic pressure differentials to overcome viscous friction and generate flows in microchannels. In this work, we investigate how the chemical and geometric properties of the channel walls ...
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Interpreting a CMS excess in lljj+missing-transverse-momentum with the golden cascade of the minimal supersymmetric standard model
(American Physical SocietyPhysical Review D, 2015-06-29)The CMS experiment recently reported an excess consistent with an invariant mass edge in opposite-sign same flavor (OSSF) leptons, when produced in conjunction with at least two jets and missing transverse momentum. We ...
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Strictly continuous extension of functionals with linear growth to the space BV
(Oxford University PressThe Quarterly Journal of Mathematics, 2015-06-24)In this paper, we prove that the integral functional F[u]: BV(Ω;ℝ^m) → ℝ defined by F[u] := ∫_Ω f(x,u(x),∇u(x))dx + ∫_Ω ∫_1^0 f^∞ (x, u^θ (x), (d D^s u)/(d |D^s u|) (x) is continuous over BV(Ω;ℝ^m), with respect to ...
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Discrete gravitational approaches to cosmology
(University of CambridgeDepartment of Applied Mathematics and Theoretical PhysicsTrinity College, 2015-06-30)Exact solutions to the Einstein field equations are notoriously difficult to find. Most known solutions describe systems with unrealistically high degrees of symmetry. A notable example is the FLRW metric underlying ...
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Light Sparticles from a Light Singlet in Gauge Mediation
(APSPhysics Review D, 2015-07-10)We revisit a simple model that combines minimal gauge mediation and the next-to-minimal supersymmetric standard model. We show that one can obtain a 125 GeV Standard Model-likeHiggs boson with stops as light as 1.1 TeV, ...
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On the generation of waves during frontogenesis
(University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2015-06-30)Density fronts are ubiquitous features of the ocean and atmosphere boundary layers. Boundary layers are characterised by strong surface fluxes of heat, water and momentum, and exhibit intense eddy fields that are associated ...
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Non-parametric Image Registration of Airborne LiDAR, Hyperspectral and Photographic Imagery of Wooded Landscapes
(IEEEIEEE Transactions on Geoscience and Remote Sensing, 2015-06-02)There is much current interest in using multisensor airborne remote sensing to monitor the structure and biodiversity of woodlands. This paper addresses the application of nonparametric (NP) image-registration techniques ...
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Metachronal waves in the flagellar beating of Volvox and their hydrodynamic origin
(Royal Society PublishingJournal of the Royal Society Interface, 2015-06-03)Groups of eukaryotic cilia and flagella are capable of coordinating their beating over large scales, routinely exhibiting collective dynamics in the form of metachronal waves. The origin of this behaviour—possibly influenced ...
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Spin alignment and differential accretion in merging black-hole binaries
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2015-06-29)Interactions between a supermassive black-hole binary and the surrounding accretion disc can both assist the binary inspiral and align the black-hole spins to the disc angular momentum. While binary migration is due to ...
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Thin-sheet flow between coalescing bubbles
(Cambridge University PressJournal of Fluid Mechanics, 2015-05-20)When two spherical bubbles touch, a hole is formed in the fluid sheet between them, and capillary pressure acting on its tightly curved edge drives an outward radial flow which widens the hole joining the bubbles. Recent ...