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Glacial erosional systems exhibit a complex, highly scaledependent phenomenology. Some aspects of modelling the development of glacial erosional landforms in response to glacial erosional processes acting over a wide range of scales are considered. The physics of ice at the glacier sole is discussed. A simple ice-water mixture theory is proposed. A method for finding the solution of the equations of motion of ice at the glacier sole based on the finite element velocities-pressure formulation is shown, which includes novel formulations for the sliding boundary condition, compression of ice and flow of water between ice and bedrock. These finite element formulations are used to simulate flows at the ice-rock interface. The use of the Laplace equation in simulating uni-axial flow is also considered, and further simulations are carried out using this equation. The results from these finite element simulations are used to consider erosional processes occurring at the glacier bed. The processes of abrasion are considered, and previous models are shown to be physically inconsistent. Cavitation, transiency and heterogeneity are shown to have an effect on clast-bed contact forces, and the local viscosity of ice is identified as being a further controlling variable on abrasion. These results are used to consider the likely development of hummocks of bedrock. A mass-balance analysis of basal debris is carried out and shown to have an important effect on erosional patterns. The equations describing the movement of a surface normal to itself are considered. Various solution techniques for these equations are tested, and requirements for the persistence of form under lowering are given. The modelling strategy used in this thesis is a nested hierarchy, with the various hierarchical levels corresponding to different scales. The effect of this hierarchisation on the modelling is discussed with respect to the generic properties of the systems, explanation and testability.

No description available.

The basal ice of temperate-type glacier Nigardsbreen is described in terms of a sediment facies model-after Lawson (1979). The ice is characterised using data obtained from sedimentological, chemical and stable isotopic analyses. These indicate that ice nearest the glacier bed is distinguishable from the ice above descriptively and genetically. In particular, the measurement of paired Oxygen and Hydrogen isotope contents, in accordance with theory proposed by Jouzel and Souchez (1982), provides a means of separating the basal facies ice component, formed by subglacial/basal regelation processes, from ice formed by 'normal' non-fractionating firnification processes. In the latter case the basic isotope content is close to that of the original precipitation whilst in the former this precipitation (meteoric) relationship is modified when ice is subjected to more or less predictable levels of fractionation during regelation. Some 1-1.5m of the basal ice, both early and late in the melt season, was found to originate from regelation. Within the basal facies ice, both stratified debris-laden layers comprising fine gravel-dominated debris up to concentrations of 1kg/l (c30% by volume) and clear intercalated ice types, reflect the regelation processes involved in debris entrainment and the freezing on of water. Thick (up to 40cm) layers of clean macrocrystalline 'regelation1 ice are considered to have been recrystallised. Coisotopic analysis may be used to highlight the fact that mixing of waters of differing origins occurs at the ice-bed interface and that the prediction of the extent of refreezing proposed by Jouzel and Souchez appears untenable. Major cation chemical analysis, undertaken to obtain data for use in the Souchez and Tison (1981) model of basal ice formational processes, which purports to discriminate between ice formed from water squeezed through the basal ice and water flowing, or ponded, at the bed, proved inconclusive. It appears that considerable desorption from clay minerals occurs and that squeezing of basal waters through the stratified facies may occur. In the absence of a clear statement of mineralogical composition in the basal debris clay fraction, which was attempted at Nigardsbreen, the Souchez and Tison model is seen to require development before it will reveal new information about basal processes. Measurements of temperature, sliding velocity and strain within subglacial cavities, in conjunction with observations on changes in sedimentological and isotopic conditions throughout the basal facies zone, are used to test and vindicate a descriptive model of the character, origin and evolution of the basal ice. The model is in turn proposed for further test.

Threaded connectors have been used in a variety of engineering structures for hundreds of years. Although stress analysis of threaded connectors has been performed since the early 1900's, there are still areas that are not fully understood. The way in which eccentricity affects the fatigue performance and stress distribution is one such area, and is the main area of research described in this thesis. The techniques of photoelasticity and fatigue testing were used to determine the effect of eccentricity on the stresses and fatigue performance of bolts. The results show that eccentric loading has a significant effect on the fatigue performance, but that this effect can be quantified if the local stress amplitude is considered. The photoelastic analysis results show the eccentricity slightly increases the stress intensity factors at the crack tip. A number of two-dimensional and three-dimensional finite element models were created to detennine the salient characteristics of the models. The models were validated against the resuh from the photoelastic analysis and the results agreed well. Accurate results can be obtained from a two-dimensional model, but the information obtained is limited unless many models are created. However, if a three-dimensional model is created more information can be obtained, but the nut thread run-out must be accurately modelled to obtain the correct stress distribution. The shape of cracks occurring in cyclically loaded steel bolts and the effect of crack shape on the stress distribution was also investigated. The photoelastic analysis of cracked bolts failed to predict the shapes of cracks occurring in cyclically loaded bolts. It is suggested that the inability of photoelasticity to model plasticity is the cause of this failure and this is supported by results from an elastic-plastic finite element model.

No description available.

The use of dough moulding compound (DMC) as a structura~ material will be feasible as more information on mechanlcal properties becomes available. In this investigation, room temperature tensile and fatigue properties were determined prior to the testing and evaluation of simple joints in DMC. The DMC was supplied in the form of compression moulded sheets. Tensile tests were conducted to British Standards specification to obtain the mechanical properties and to identify possible sources of variability in properties. Differences in tensile strength due to sheet-to-sheet variability and specimen orientation within a sheet were significant but there was no significant variation due to the cross-head speed over the range O.05mm/min to 300mm/min. Tensile fatigue tests were conducted to British Standards specification. The scatter of fatigue lives was found to be greater than that for other reinforced plastics, but was adequately described by both the Log-Normal and Weibull distributions. In tensile and fatigue tests on larger specimens there was no size effect on tensile strength, but the fatigue strength at a given life and probability of failure was reduced ,slightly. When specimens contained bolt holes, the tensile strength decreased marginally, but the fatigue strength was not affected. Transverse compressive stresses due to a bolt load had little effect on the fatigue behaviour and changes in the cyclic-or static stress did not significantly alter the bolt load relaxation. Cyclic stress was found to cause greater bolt load relaxation than the corresponding mean stress. In tensile and fatigue tests on single shear lap joints, benditig wa~ the main cause of failure and the joint efficiency was low, 43% in tension and 51% in fatigue. By loading the specimens through the bolts at one end, bending was eliminated and the joint efficiency increased to 62% in tension and to 78% in fatigue

When radio echo sounding polar ice sheets weak stratified reflections are visible deep inside the ice sheets. These reflections are often called internal layers. Previously it has been suggested as a result of glacier flow models that these reflections can be treated as surfaces of equal age. In order for a reflection to be related to a single age feature in an ice sheet a one dimensional wave model must be adequate to model the propagation of a wavelet down to the feature and back to the surface. In this thesis four different one dimensional models are constructed each including different physics. It is shown that for the frequencies of interest to radio echo sounding it is sufficient to use the non-dispersive high frequency values of permittivity and conductivity for the ice in the models. The models are used on data from two drill sites. The first site is Berkner Island where I constructed an instrument to measure the electrical conductivity of the 181 metre long ice core. The second site is the Greenland Ice Core Project (GRIP) site at Summit of length 3028 metres. For both sites permittivity and conductivity profiles inside the ice sheet are calculated and put into the models with an estimate of the transmitted wavelet to produce expected radio echo profiles at the sites. For Berkner despite altering many parameters no match between model result and radar data was obtained. For GRIP a satisfactory match was obtained between model result and radar data. It is concluded that the weak, specular (plane like), st Ratified reflections at depth can be treated as isochrones. The strong reflections at shallow depths are a result of a combination of spherical reflection surfaces and interference between many closely spaced layers and cannot necessarily be treated as isochrones.

Introduction: The point of departure in this thesis is that women live longer than men, while men have more power, influence and resources, and probably better health-related quality of life, than women. In order to judge and act from this situation, the classical idea that both facts and values are needed for conclusion is adopted. The diverse positions of the sexes are mainly assumed to depend on the gender system, i.e. the societal structure organising human activities and relations, ultimately privileges and burdens, by sex. Hence, abolition of gender is held to be associated with decreased differences in health. The handling of facts and values is divided into two principal questions: 1) how to compare women and men within a particular state of the world, and 2) how to choose from their positions between states. Aims: The overall aim is to propose a public health framework for judging fairness and change from the positions of women and men. The specific aims are to: illustrate how the choice of normative approach affects judgements on fairness and resource allocation (I), explor public health views regarding various ethical principles (II), study the relationship between aspects of gender equality in public/domestic and health (III), estimate costs, savings and health gains, associated with the Swedish parental insurance reform (IV). Methods: The methods used are: ethical analysis based on the normative theories of welfarism, extrawelfarism, egalitarianism, and feminism; and the notions of justice by separate spheres, equity as choice and attainment/shortfall principles (I), survey among public health workers regarding within-state and between-states ethical views (II), epidemiologic study on death and sickness leave among traditional, equal, and untraditional Swedish couples who had their first child in 1978 (III), cost-effectiveness analysis based on men who took paternity leave 1978-1979 (IV). Results: The selected normative theories are likely to claim different opinions on fairness regarding women and men, and different proposals on resource allocations (I). Most public health workers support the idea of judging fairness by separate spheres, end-points, and shortfall equity. The rejection of health maximisation, and support for equality in life span and income, are convincing; although females and males differ significantly in judging societal change (II). In comparison to being equal in the public sphere, traditional women have lower risks of death and sickness, while traditional men tend to have higher risks. Being equal in the domestic sphere seems to be associated with lower risks among both sexes (III). Men who took paternity leave run significant lower death risks than other men. Base case cost-effectiveness of the reform is 6,000 EUR, and worst case 40,000 EUR, per gained QALY (IV). Conclusions: A public health framework for judging fairness and reform by women and men could look as follows: 1) identify facts at present and from past, 2) ask whether the situation is fair by within-state rules, 3) claim or refuse change, 4) identify consequences from reform, 5) consider whether the change was satisfying by between-states rules. The gains from more ethical analyses of public health based on sex/gender should overcome the many tricky issues involved. Since there is no common understanding on how to judge fairness and change from female/male differences in health and wealth, added research and exchange of views are called for. At Swedish state of gender (in)equality, it seems public health relevant to support further similarity in child-care. Provided an effective fraction of 25 percent, the entitlement to paternity leave is probably approved of by common welfarist, egalitarian, and feminist goals.

This study examines the effects of various rib properties and reinforced section geometries on the splitting force distribution around tensile lapped splices. The study makes use of a test specimen which idealizes the situation that exists in a tensile lapped splice between adjacent lateral cracks. The test specimen always failed by a longitudinal splitting of the concrete cover along a predefined failure plane. During the study the Influence of relative rib area, rib profile, amount of secondary link reinforcement, lateral pressure and bar spacing within the lap on the ultimate bond strength of the lap were examined. It was found that, for hot rolled (untwisted) deformed bars with crescent shaped ribs the orientation of the ribs to the splitting plane significantly affected the ultimate bond strength of the test specimen and, whilst the relative rib area was a good measure of a deformed bars performance In bond, it could not distinguish between the different orientations used. Further, since the maximum percentage Increase In ultimate bond stress for the same bar between orientations was of a similar magnitude to that observed for a doubling of a bars relative rib area the author recommends that bar orientation be taken into account when detailing tensile lapped splices. The presence of link steel perpendicular to the splitting plane did not significantly influence the ultimate bond strength of the model test specimen although the presence of lateral pressure did. The stress in the links at the occurrence of a full length splitting crack was less than 100 N/mm2. The finite element method was used to examine the two fundamental hypotheses describing the bond action of deformed reinforcing bars and to examine the implications of the assumption that the splitting forces around the circumference of a reinforcing bar are distributed proportionally to the rib height. The finite element analysis was also used to study the effect of varying the distance between the lapped bars on the spitting force distribution around the lapped bars. The results of a linear elastic analysis showed that both rib profile and bar spacing had a significant effect on the distribution of splitting forces around a tension lapped splice