African University of Science and Technology: Recent submissions

Now showing items 621-640 of 4790

  • Efficient mixing in stratified flows: experimental study of a Rayleigh-Taylor unstable interface within an otherwise stable stratification 

    Davies-Wykes, Megan S; Dalziel, Stuart Bruce (Cambridge University PressJournal of Fluid Mechanics, 2014-09-09)
    Boussinesq salt-water laboratory experiments of Rayleigh–Taylor instability (RTI) can achieve mixing efficiencies greater than 0.75 when the unstable interface is confined between two stable stratifications. This is much ...

  • On the thermodynamic boundary conditions of a solidifying mushy layer with outflow 

    Rees, Jones David W; Worster, Michael Grae (CUPJournal of Fluid Mechanics, 2014-11-27)
    The free-boundary problem between a liquid region and a mushy layer (a reactive porous medium) must respect both thermodynamic and fluid dynamical considerations. We develop a steady two-dimensional forced-flow configuration ...

  • A physically based parameterization of gravity drainage for sea-ice modelling 

    Rees, Jones David W; Worster, Michael Grae (Wiley on behalf of the American Geophysical UnionJournal of Geophysical Research: Oceans, 2014-09-02)
    We incorporate a physically derived parameterization of gravity drainage, in terms of a convective upwelling velocity, into a one-dimensional, thermodynamic sea- ice model of the kind currently used in coupled climate ...

  • Vortex rings impinging on permeable boundaries 

    Mujal-Colilles, Anna; Dalziel, Stuart Bruce; Bateman, Allen (Physics of Fluids, 2015-01-17)
    Experiments with vortex rings impinging permeable and solid boundaries are presented in order to investigate the influence of permeability. Utilizing Particle Image Velocimetry, we compared the behaviour of a vortex ring ...

  • Redshifting of cosmological black bodies in BSBM varying-alpha theories 

    Barrow, John David; Magueijo, João (APSPHYSICAL REVIEW D, 2014-12-04)
    We analyse the behaviour of black-body radiation in theories of electromagnetism which allow the electron charge and the fine structure constant to vary in space and time. We show that such theories can be expressed as ...

  • Higher order corrections and unification in the minimal supersymmetric standard model: SOFTSUSY3.5 

    Allanach, Benjamin Christopher; Bednyakov, A; Ruiz, de Austri R (ElsevierComputer Physics Communications, 2014-12-18)
    We explore the effects of three-loop minimal supersymmetric standard model renormalisation group equation terms and some leading two-loop threshold corrections on gauge and Yukawa unification: each being one loop higher ...

  • Minimal Massive 3D Gravity Unitarity Redux 

    Arvanitakis, Alex S; Townsend, Paul Kingsley (IOPClassical and Quantum Gravity, 2015-02-26)
    A geometrical analysis of the bulk and anti-de Sitter boundary unitarity conditions of 3D “Minimal Massive Gravity” (MMG) (which evades the “bulk/boundary clash” of Topologically Massive Gravity) is used to extend and ...

  • Limits on a Gravitational Field Dependence of the Proton{Electron Mass Ratio from H2 in White Dwarf Stars 

    Bagdonaite, J; Salumbides, EJ; Preval, SP; Barstow, MA; Barrow, John David; Murphy, MT; Ubachs, W (American Physical SocietyPhysical Review Letters, 2014-09-18)
    Spectra of molecular hydrogen (H2) are employed to search for a possible proton-to-electron mass ratio (μ) dependence on gravity. The Lyman transitions of H2, observed with the Hubble Space Telescope towards white dwarf ...

  • Explaining the CMS eejj Excess With R−parity Violating Supersymmetry and Implications for Neutrinoless Double Beta Decay 

    Allanach, Benjamin Christopher; Biswas, Sanjoy; Mondal, Subhadeep; Mitra, Manimala (American Physical SocietyPhysical Review D, 2015-01-28)
    The recent CMS searches for the right handed gauge boson WR reports an interesting deviation from the Standard Model. The search has been conducted in the eejj channel and has shown an excess around meejj ~ 2 TeV. In this ...

  • Resonant slepton production yields CMS eejj and epTjj excesses 

    Allanach, Benjamin Christopher; Biswas, Sanjoy; Mondal, Subhadeep; Mitra, Manimala (APS, 2015-01-13)
    Recent CMS searches for dileptoquark production report local excesses of 2.4σ in an eejj channel and 2.6σ in an epTjj channel. Here, we simultaneously explain both excesses with resonant slepton production in R-parity ...

  • Maximum Tension: with and without a cosmological constant 

    Barrow, John David; Gibbons, Gary William (OUPMonthly Notices of the Royal Astronomical Society, 2014-12-04)
    We discuss various examples and ramifications of the conjecture that there exists a maximum force (or tension) in general relativistic systems. We contrast this situation with that in Newtonian gravity, where no maximum ...

  • Quantum theory from the perspective of general probabilistic theories 

    Al-Safi, Sabri Walid (University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2015-03-03)
    This thesis explores various perspectives on quantum phenomena, and how our understanding of these phenomena is informed by the study of general probabilistic theories. Particular attention is given to quantum nonlocality, ...

  • Multiple solutions in supersymmetry and the Higgs 

    Allanach, Benjamin Christopher (The Royal Society PublishingPhilosophical Transactions of the Royal Society A, 2014-11-24)
    Weak-scale supersymmetry is a well-motivated, if speculative, theory beyond the Standard Model of particle physics. It solves the thorny issue of the Higgs mass, namely: how can it be stable to quantum corrections, when ...

  • Jordan-Wigner formalism for arbitrary 2-input 2-output matchgates and their classical simulation 

    Jozsa, Richard; Miyake, Akimasa; Strelchuk, Sergii (Rinton PressQuantum Information and Computation, 2015-05-01)
    In Valiant's matchgate theory, 2-input 2-output matchgates are 4 4 matrices that satisfy ten so-called matchgate identities. We prove that the set of all such matchgates (including non-unitary and non-invertible ones) ...

  • The convective desalination of sea ice 

    Rees Jones, David (University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2014-07-01)
    This thesis aims to improve our understanding of the fundamental processes affecting the growth of sea ice in the polar oceans in order to improve climate models. Newly formed sea ice contains a significant amount of salt ...

  • Asymptotic approximations for the sound generated by aerofoils in unsteady subsonic flows 

    Ayton, Lorna Jane (University of CambridgeDepartment of Applied Mathematics and Theoretical PhysicsChurchill College, 2014-10-07)
    This thesis considers the sound generated by unsteady perturbations interacting with solid aerofoils in background steady flows, in an attempt to further develop analytic models for the noise generated by blades within ...

  • Secondary instability and tertiary states in rotating plane Couette flow 

    Daly, CA; Schneider, Tobias M; Schlatter, Philipp; Peake, Nigel (Cambridge University PressJournal of Fluid Mechanics, 2014-11-14)
    Recent experimental studies have shown rich transition behaviour in rotating plane Couette ow (RPCF). In this paper we study the transition in supercritical RPCF theoretically by determination of equilibrium and periodic ...

  • Shearing waves and the MRI dynamo in stratified accretion discs 

    Donnelly, Cara (University of CambridgeDepartment of Applied Mathematics and Theoretical Physics, 2014-01-07)
    Accretion discs efficiently transport angular momentum by a wide variety of as yet imperfectly understood mechanisms, with profound implications for the disc lifetime and planet formation. We discuss two different methods ...

  • CLEANING OF VISCOUS DROPS ON A FLAT INCLINED SURFACE USING GRAVITY-DRIVEN FILM FLOWS 

    Landel, Julien R; McEvoy, Harry; Dalziel, Stuart Bruce (ElsevierFood and Bioproducts Processing, 2014-10-07)
    We investigate the fluid mechanics of cleaning viscous drops attached to a flat inclined surface using thin gravity-driven film flows. We focus on the case where the drop cannot be detached from the surface by the mechanical ...

  • Cleaning of Viscous Droplets on an Inclined Planar Surface Using Film Flows 

    Landel, JR; Thomas, AL; McEvoy, H; Dalziel, Stuart Bruce (Australian Fluids Mechanics SocietyProceedings of the Nineteenth Australasian Fluid Mechanics Conference, 2014)
    We investigate the fluid mechanics of cleaning viscous drops attached to a flat inclined surface using thin gravity-driven film flows. We focus on the case where the drop cannot be detached from the surface by the mechanical ...