DSpace Community:http://hdl.handle.net/2440/2992018-01-22T06:14:45Z2018-01-22T06:14:45ZOn the calculation of normal modes of a coupled ice-shelf/sub-ice-shelf cavity systemMeylan, M.Bennetts, L.Hosking, R.Catt, E.http://hdl.handle.net/2440/1102272018-01-09T23:48:32Z2017-01-01T00:00:00ZTitle: On the calculation of normal modes of a coupled ice-shelf/sub-ice-shelf cavity system
Author: Meylan, M.; Bennetts, L.; Hosking, R.; Catt, E.
Abstract: A corrected solution method is presented for a mathematical model of wave motions in a coupled ice-shelf/sub-iceshelf water-cavity system. The method is used to calculate the periods of the system’s normal modes, and the longest periods are shown to be significantly larger than those calculated using an existing method containing errors. Highly accurate approximations of the normal-mode periods are obtained for a model involving a single non-spectral physical parameter - the shelf/cavity length.2017-01-01T00:00:00ZOn the generalized reward generator for stochastic fluid models: a new equation for ΨSamuelson, A.O Reilly, M.Bean, N.http://hdl.handle.net/2440/1101372018-01-07T22:37:50Z2017-01-01T00:00:00ZTitle: On the generalized reward generator for stochastic fluid models: a new equation for Ψ
Author: Samuelson, A.; O Reilly, M.; Bean, N.
Abstract: We construct a generalized reward matrix Z(s), which is an extension of the fluid generator Q(s) of a stochastic fluid model (SFM). We consider the generators that are projections of Z(s), including the generator Q(s), and discuss the application of the resulting generators in different contexts. One such projection, Z⁺(s), is used to define a matrix M, which records the expected number of crossings of level 0. We use the elements of M and its physical interpretation to derive an explicit equation for the matrix ψ, which is a key building block to many other performance measures. Work on algorithmic techniques to efficiently compute M are in progress.2017-01-01T00:00:00ZDetection of coherent structures in photospheric turbulent flowsChian, A.Rempel, E.Aulanier, G.Schmieder, B.Shadden, S.Welsch, B.Yeates, A.http://hdl.handle.net/2440/1100882018-01-02T22:07:40Z2014-01-01T00:00:00ZTitle: Detection of coherent structures in photospheric turbulent flows
Author: Chian, A.; Rempel, E.; Aulanier, G.; Schmieder, B.; Shadden, S.; Welsch, B.; Yeates, A.
Abstract: We study coherent structures in solar photospheric flows in a plage in the vicinity of the active regionAR10930 using the horizontal velocity data derived from Hinode/Solar Optical Telescope magnetograms. Eulerian and Lagrangian coherent structures (LCSs) are detected by computing the Q-criterion and the finite-time Lyapunov exponents of the velocity field, respectively. Our analysis indicates that, on average, the deformation Eulerian coherent structures dominate over the vortical Eulerian coherent structures in the plage region. We demonstrate the correspondence of the network of high magnetic flux concentration to the attracting Lagrangian coherent structures (aLCSs) in the photospheric velocity based on both observations and numerical simulations. In addition, the computation of aLCS provides a measure of the local rate of contraction/expansion of the flow.2014-01-01T00:00:00ZModelling the floating ladder track response to a moving load by an infinite Bernoulli-Euler beam on periodic flexible supportsHosking, R.Milinazzo, F.http://hdl.handle.net/2440/1099942017-12-14T22:32:43Z2012-01-01T00:00:00ZTitle: Modelling the floating ladder track response to a moving load by an infinite Bernoulli-Euler beam on periodic flexible supports
Author: Hosking, R.; Milinazzo, F.
Abstract: An infinite Bernoulli-Euler beam (representing the “combined rail” consisting of the rail and longitudinal sleeper) mounted on periodic flexible point supports (representing the railpads) has already proven to be a suitable mathematical model for the floating ladder track (FLT), to define its natural vibrations and its forced response due to a moving load. Adopting deliberately conservative parameters for the existing FLT design, we present further results for the response to a steadily (uniformly) moving load when the periodic supports are assumed to be elastic, and then introduce the mass and viscous damping of the periodic supports. Typical support damping significantly moderates the resulting steady deflexion at any load speed, and in particular substantially reduces the magnitude of the resonant response at the critical speed. The linear mathematical analysis is then extended to include the inertia of the load that otherwise moves uniformly along the beam, generating overstability at supercritical speeds - i.e. at load speeds notably above the critical speed predicted for the resonant response when the load inertia is neglected. Neither the resonance nor the overstability should prevent the safe implementation of the FLT design in modern high speed rail systems.2012-01-01T00:00:00Z