Tidal modulation of two-layer hydraulic exchange flows

International audienceTime-dependent, two layer hydraulic exchange flow is studied using an idealised shallow water model. It is found that barotropic time-dependent perturbations, representing tidal forcing, increase the baroclinic exchange flux above the steady hydraulic limit, with flux increasing monotonically with tidal amplitude (measured either by height or flux amplitude over a tidal period). Exchange flux also depends on the non-dimensional tidal period, ?, which was introduced by by Helfrich (1995). When tidal amplitude is characterised by the barotropic flux amplitude, exchange flux is a monotonic function of ? as predicted by Helfrich (1995). However, the relationship between the (imposed) free surface amplitude and flux amplitude is complicated by reflections within the channel and by the baroclinic response of the two layer system, leading to a non-monotonic relationship between the height amplitude and ?

Lloyd's Coppice Landslip Study Phase 1 : design of site investigation programme

This report, commissioned by Telford and Wrekin Council, provides a strategy for investigating the instability of the Lloyd's Coppice landslip, near Ironbridge. Recommendations are given for a drilling programme that will assist in modelling the geological sequence exposed in the sides of the Coppice, and form a basis for a stability assessment. The recommendations are based on a limited desk study using information provided by the Council, and a one day walkover survey

The Energetics of Southern Ocean Upwelling

The ocean’s meridional overturning circulation is closed by the upwelling of dense, carbon-rich waters to the surface of the Southern Ocean. It has been proposed that upwelling in this region is driven by strong westerly winds, implying that the intensification of Southern Ocean winds in recent decades may have enhanced the rate of upwelling, potentially affecting the global overturning circulation. However, there is no consensus on the sensitivity of upwelling to winds or on the nature of the connection between Southern Ocean processes and the global overturning circulation. In this study, the sensitivity of the overturning circulation to changes in Southern Ocean westerly wind stress is investigated using an eddy-permitting ocean–sea ice model. In addition to a suite of standard circulation metrics, an energy analysis is used to aid dynamical interpretation of the model response. Increased Southern Ocean wind stress enhances the upper cell of the overturning circulation through creation of available potential energy in the Southern Hemisphere, associated with stronger upwelling of deep water. Poleward shifts in the Southern Ocean westerlies lead to a complicated transient response, with the formation of bottom water induced by increased polynya activity in the Weddell Sea and a weakening of the upper overturning cell in the Northern Hemisphere. The energetic consequences of the upper overturning cell response indicate an interhemispheric connection to the input of available potential energy in the Northern Hemisphere

Irreversible and reversible modes of operation of deterministic ratchets

We discuss a problem of optimization of the energetic efficiency of a simple rocked ratchet. We concentrate on a low-temperature case in which the particle's motion in a ratchet potential is deterministic. We show that the energetic efficiency of a ratchet working adiabatically is bounded from above by a value depending on the form of ratchet potential. The ratchets with strongly asymmetric potentials can achieve ideal efficiency of unity without approaching reversibility. On the other hand we show that for any form of the ratchet potential a set of time-protocols of the outer force exist under which the operation is reversible and the ideal value of efficiency is also achieved. The mode of operation of the ratchet is still quasistatic but not adiabatic. The high values of efficiency can be preserved even under elevated temperatures

Integrating Western and non-Western cultural expressions to further cultural and creative tourism: a case study

The term cultural industries was coined more than half a century ago, but at the beginning of the twenty-first century, the broader concept of creative industries, covering a wide range of cultural, design and digital activity, captured the imagination of public policymakers at national and city levels. Paralleling these developments has been the recognition of the phenomenon of cultural tourism and, more recently, the emergence of the idea of creative tourism, that is, tourism programmes designed to engage tourists actively in cultural activity. This paper presents a case study of a creative tourism event which took place in 2012 in the City of Manchester in the UK. The festival, which celebrated West African culture, utilised existing cultural institutions of the city and drew on the talents of local and visiting members of West African community to engage not only tourists but also indigenous and Black and Minority Ethnic (BME) residents of Manchester in a variety of cultural activities. It thus used the focus of creative tourism to seek to foster community and cultural development as well as tourism

Effects of sea level rise on salinity and tidal flooding patterns in the Guadiana Estuary

Sea level rise is a worldwide concern as a high percentage of the population accommodates coastal areas. The focus of this study is the impact of sea level rise in the Guadiana Estuary, an estuary in the Iberian Peninsula formed at the interface of the Guadiana River and the Gulf of Cadiz. Estuaries will be impacted by sea level rise as these transitional environments host highly diverse and complex marine ecosystems. The major consequences of sea level rise are the intrusion of salt from the sea into fresh water and an increase in flooding area. As the physical, chemical, and biological components of estuaries are sensitive to changes in salinity, the purpose of this study is to further evaluate salt intrusion in the Guadiana Estuary caused by sea level rise. Hydrodynamics of the Guadiana Estuary were simulated in a two-dimensional numerical model with the MOHID water modeling system. A previously developed hydrodynamic model was implemented to further examine changes in salinity distribution in the estuary in response to sea level rise. Varying tidal amplitudes, freshwater discharge from the Guadiana River and bathymetries of the estuary were incorporated in the model to fully evaluate the impacts of sea level rise on salinity distribution and flooding areas of the estuary. Results show an overall increase in salinity and land inundation in the estuary in response to sea level rise.info:eu-repo/semantics/publishedVersio

Exploring the structure of glass-forming liquids using high energy X-ray diffraction, containerless methodology and molecular dynamics simulation

High energy X-ray diffraction can be combined with containerless techniques to provide information on the atomic arrangements in glass-forming liquids in stable and metastable regimes. The high incident energies provide bulk diffraction data to high values of scattering vector which enables significantly more robust analysis of the local and medium-range order that influences important physical properties such as viscosity and crystal nucleation. These combined techniques have been applied to a range of oxide liquids. In this contribution we illustrate addition of further dimensions to phase space by controlling the partial pressure of oxygen that permits the study liquids containing iron. The advantages of rapid data acquisition are also demonstrated in a study of tellurite glass-forming systems where a transition from ergodic to non-ergodic regimes in the deeply supercooled liquid is shown. Finally we demonstrate how descriptions of the liquid structure can be developed by combining HEXRD with molecular dynamics simulations

Exploring the structure of glass-forming liquids using high energy X-ray diffraction, containerless methodology and molecular dynamics simulation

High energy X-ray diffraction can be combined with containerless techniques to provide information on the atomic arrangements in glass-forming liquids in stable and metastable regimes. The high incident energies provide bulk diffraction data to high values of scattering vector which enables significantly more robust analysis of the local and medium-range order that influences important physical properties such as viscosity and crystal nucleation. These combined techniques have been applied to a range of oxide liquids. In this contribution we illustrate addition of further dimensions to phase space by controlling the partial pressure of oxygen that permits the study liquids containing iron. The advantages of rapid data acquisition are also demonstrated in a study of tellurite glass-forming systems where a transition from ergodic to non-ergodic regimes in the deeply supercooled liquid is shown. Finally we demonstrate how descriptions of the liquid structure can be developed by combining HEXRD with molecular dynamics simulations