A l-D tidally resolving hydrodynamic model of the Tweed Estuary has been encoded using the Estuarine Contaminant Simulator, ECoS. The model results of axial and time series variations in water elevation, salinity and turbidity are compared to field data recorded during the LOIS survey programme. The organic and inorganic controls on estuarine pH have also been investigated by encoding a new template to predict the effect of changing salinity and temperature on the pH of estuarine water. The template has been coupled to the hydrodynamic model to predict pH variations in the estuary. The model results have shown conservative behaviour of the inorganic carbon system through out the majority of the estuary, but also identified an area of potentially high photosynthetic activity near the limit of saline intrusion during periods of low summer flows. Low (< 2 ^g 1"') concentrations of chlorophyll a in the water column and increases in pH correlated with tidal inundation of the river estuary banks imply that benthic photosynthetic process are important water chemistry in the upper estuary. The effects of salinity, turbidity and pH on Kd(Cd) and K<i(Zn) has been investigated using radiotracer incubation experiments and analytically determined measurements. The results show a reduction in IQ with increased salinity, but that the K<iS determined analytically are an order of magnitude higher than those measured when radiotracers are used. Analytically determined K<iS are reduced with increasing SPM concentration and increased at higher pH. Although no photosynthetically mediated control of radiotracer uptake was identified partitioning was significantly reduced (> 90 %) when a metabolic inhibitor was added. The Kd has been encoded as an exchange transfer and used to predict axial distributions and the flux of these metals from the riverine catchment to the sea. Model results indicate that the partition coefficients determined fi-om the radiotracer studies can not fully account for the analytically determined distribution between phases. It is hypothesised that colloids and Fe-Mn oxides precipitates play a significant role in trace metal transpon in low turbidity, high pH conditions. The results have implications for the measurement and modelling of chemical fluxes in low turbidity systems.

This research concentrates on damage ship stability and means for assessing dynamic ship performance in this state. A consolidation of many approaches for tackling damage ship dynamics has been undertaken, culminating in the development of a numerical tool for simulating ship behaviour while accounting for progressive flooding and the ensuing effects of floodwater motion. General features that have been accounted for in a new purposely developed numerical program PROTEUS3 include the following: Linear concepts regarding intact ship hydrodynamics based on strip theory and Rankine source method (RSM). These are further utilised by convolution and spectral transformations in deriving relevant time domain force realisations. Non-linear excitation/restoring forces calculated from pressure integration up to the instantaneous undisturbed wave profile. Non-linearities in hydrodynamic properties arising from variation of mean underwater geometry due to occurrence of non-stationary asymm etries in mass distribution are taken into account by a database approach. Forward speed in arbitrary heading. Progressive flooding through a ship with any internal subdivision and floodwater motion simulations based on free-mass-on-potential-surface (FMPS) model. Non-linear treatment of the effects of cargo shift or floodwater motions on the overall ship dynamic behaviour. The underlying modelling has been explained by rigorous derivation of all the relevant equations from first principles. Validity of the model has been tested comprehensively through comparison with available physical model tests data. A thorough investigation on the new effects of modelling advancements concerning the accuracy of the developed model has been undertaken and the results are presented and discussed. Despite the introduction of simplifying assumptions concerning floodwater behaviour, the predictions show consistency with physical experimental data. It is believed that this pragmatic approach constitutes a very efficient tool for predictions of vessel performance in extremely adverse conditions. This effectiveness has been demonstrated by undertaking forensic analysis of two of the most controversial accidents of the last two decades, namely the loss of MV Derbyshire and the NW Estonia disaster.

No description available.

The explosion of massive stars involves the formation of a shock wave. In stars that develop iron cores, this shock wave stalls on its way out due to neutrino emission and the breakup of heavy nuclei flowing through the shock. For the explosion to succeed, a fraction of the gravitational binding energy of the collapsed core that is radiated in neutrinos needs to be absorbed by the material below the shock. How much energy is needed depends on the interplay between non-spherical hydrodynamic instabilities, neutrino heating, and nuclear dissociation. This thesis seeks to understand this interplay through numerical experiments that model the key physical components of the system and separate them out to examine their individual effects. Specifically, one- and two-dimensional time-dependent hydrodynamic simulations are performed to study the effects of non-spherical shock oscillations, neutrino-driven convection, and alpha particle recombination on the dynamics of the system and the critical heating rate for explosion. We find that nuclear dissociation has a significant effect on the linear stability and saturation amplitude of shock oscillations. At the critical neutrino heating rate for an explosion, convection due to a negative entropy gradient plays a major role in driving dipolar shock motions. One dimensional explosions are due to a global instability involving the advection of entropy perturbations from the shock to the region where the accretion flow cools due to neutrino emission. Large scale shock expansions in two-dimensions are due to a finite amplitude instability involving the balance between buoyancy forces and the ram pressure of the flow upstream of the shock. During these expansions, a significant amount of energy is released when nucleons recombine into alpha particles, constituting a significant last step in the transition to explosion. The critical neutrino heating rate for an explosion depends sensitively on the starting radius of the shock relative to the radius at which the binding energy of an alpha particle is comparable to the gravitational binding energy.

No description available.

xi, 178 leaves : ill., maps, charts (some fold.) ; 28 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1975)--University of Adelaide, Dept. of Applied Mathematics, 1975

vi, 110 leaves : ill. ; 30 cm / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1980

Thesis (Ph.D.)--Tufts University, 2001. / Adviser: Mark Cronin-Golomb. Submitted to the Dept. of Electrical Engineering. Includes bibliographical references (leaves 16-18). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (MScIng)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.