Department of Materials Science and Metallurgy: Recent submissions
Now showing items 341-360 of 648
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The mean value theorem and Taylor’s theorem for fractional derivatives with Mittag–Leffler kernel
(SpringerAdvances in Difference Equations, 2018-12-01)We establish analogues of the mean value theorem and Taylor’s theorem for fractional differential operators defined using a Mittag-Leffler kernel. We formulate a new model for the fractional Boussinesq equation by using ...
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Experimental exploration of fluid-driven cracks in brittle hydrogels
(Cambridge University PressJournal of Fluid Mechanics, 2018-06-10)Hydraulic fracturing is a procedure by which a fracture is initiated and propagates due to pressure (hydraulic loading) applied by a fluid introduced inside the fracture. In this study we focus on a crack driven by an ...
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Leading-order Stokes flows near a corner
(OUPIMA Journal of Applied Mathematics (Institute of Mathematics and Its Applications), 2018-07-25)Singular solutions of the Stokes equations play important roles in a variety of fluid dynamics problems. They allow the calculation of exact flows, are the basis of the boundary integral methods used in numerical computations, ...
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Quantized Skyrmions from SU(4) weight diagrams
(Physical Review C, 2018-03-06)© 2018 authors. Published by the American Physical Society. Starting from solutions of the lightly bound Skyrme model, we construct many new Skyrmion solutions of the standard Skyrme model with tetrahedral or octahedral ...
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Spiral density waves and vertical circulation in protoplanetary discs
(Oxford University PressMonthly Notices of the Royal Astronomical Society, 2018-06-01)Spiral density waves dominate several facets of accretion disc dynamics – planet-disc interactions and gravitational instability (GI) most prominently. Though they have been examined thoroughly in two-dimensional simulations, ...
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Lattice QCD calculation of the B-(s) -> D-(s)* lv form factors at zero recoil and implications for vertical bar V-cb vertical bar
(PHYSICAL REVIEW D, 2018-03-09)© 2018 authors. We present results of a lattice QCD calculation of B→D∗ and Bs→Ds∗ axial vector matrix elements with both states at rest. These zero recoil matrix elements provide the normalization necessary to infer a ...
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Quasi-periodic oscillations and the global modes of relativistic, MHD accretion discs
The high-frequency quasi-periodic oscillations (HFQPOs) that punctuate the light curves of X-ray binary systems present a window onto the intrinsic properties of stellar-mass black holes and hence a testbed for general ...
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An analytically-based method for predicting the noise generated by the interaction between turbulence and a serrated leading edge
(ElsevierJournal of Sound and Vibration, 2018-05-26)This paper considers the interaction of turbulence with a serrated leading edge. We investigate the noise produced by an aerofoil moving through a turbulent perturbation to uniform flow by considering the scattered pressure ...
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Rough surface reconstruction at grazing angles by an iterated marching method.
(Optical Society of AmericaJournal of the Optical Society of America. A, Optics, image science, and vision, 2018-04)An iterated marching method is presented for reconstruction of rough perfectly reflecting 1-dimensional surfaces from scattered data arising from a scalar wave at grazing incidence. This is based on coupled inte- gral ...
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Large-scale stability and astronomical constraints for coupled dark-energy models
(American Physical SocietyPhysical Review D, 2018-02-26)The physics of the dark energy and the dark matter is still an open issue in cosmology. The dark energy occupies about 68.5% of the total energy density of the universe today [1], and is believed to accelerate its observed ...
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Testing linear marginal stability in stratified shear layers
We use two-dimensional direct numerical simulations of Boussinesq stratified shear layers to investigate the influence of the minimum gradient Richardson number Rim on the early time evolution of Kelvin–Helmholtz instability ...
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On nonrelativistic 3D spin-1 theories
We describe non-relativistic limits of the 3D Proca and $\sqrt{\rm Proca}$ theories that yield spin-1 Schroedinger equations. Analogous results are found by generalized null reduction of the 4D Maxwell or complex self-dual ...
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Horizontal locomotion of a vertically flapping oblate spheroid
(Cambridge University PressJournal of Fluid Mechanics, 2018-04-10)We consider the self-induced motions of three-dimensional oblate spheroids of density $\rho_s$ with varying aspect ratios $AR=b/c \leq 1$, where $b$ and $c$ are the spheroids' centre-pole radius and centre-equator radius ...
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Seven lessons from manyfield inflation in random potentials
(IoPJOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2018-01)We study inflation in models with many interacting fields subject to randomly generated scalar potentials. We use methods from non-equilibrium random matrix theory to construct the potentials and an adaption of the ‘transport ...
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Connection between nonlinear energy optimization and instantons.
(American Physical SocietyPhysical review. E, 2018-01)How systems transit between different stable states under external perturbation is an important practical issue. We discuss here how a recently developed energy optimization method for identifying the minimal disturbance ...
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Interaction between the Blasius boundary layer and a free surface
(Cambridge University PressJournal of Fluid Mechanics, 2018-03-25)We consider the steady, supercritical flow of a fluid layer. The layer is bounded above by a free surface and below by a rigid no-slip base. The base is in two parts: the downstream part of the base is stationary, while ...
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New integrable models and analytical solutions in f(R) cosmology with an ideal gas
(American Physical SocietyPhysical Review D - Particles, Fields, Gravitation and Cosmology, 2018-01-23)In the context of f(R)-gravity with a spatially flat FLRW metric containing an ideal fluid, we use the method of invariant transformations to specify families of models which are integrable. We find three families of f(R) ...
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Twistor description of spinning particles in AdS
(Springer NatureJournal of High Energy Physics, 2018-01-01)The two-twistor formulation of particle mechanics in D-dimensional anti-de Sitter space for D=4,5,7, which linearises invariance under the AdS isometry group Sp(4;K) for K=R,C,H,, is generalized to the massless N-extended ...
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A possible failure of determinism in general relativity
(American Physical SocietyPhysics, 2018-01-17)Is the future predictable? If we know the initial state of a system exactly, then do the laws of physics determine its state arbitrarily far into the future? In Newtonian mechanics, the answer is yes. Similarly in ...
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A lower bound on the positive semidefinite rank of convex bodies
The positive semidefinite rank of a convex body $C$ is the size of its smallest positive semidefinite formulation. We show that the positive semidefinite rank of any convex body $C$ is at least $\sqrt{\log d}$ where $d$ is ...
