A coupled tide-wave model for the NW European shelf seas

Understanding the interaction of tides and waves is essential in many studies, including marine renewable energy, sediment transport, long-term seabed morphodynamics, storm surges and the impacts of climate change. In the present research, a COAWST model of the NW European shelf seas has been developed and applied to a number of physical processes. Although many aspects of wave�current interaction can be investigated by this model, our focus is on the interaction of barotropic tides and waves at shelf scale. While the COWAST model was about five times more computationally expensive than running decoupled ROMS (ocean model) and SWAN (wave model), it provided an integrated modelling system which could incorporate many wave�tide interaction processes, and produce the tide and wave parameters in a unified file system with a convenient post-processing capacity. Some applications of the model such as the effect of tides on quantifying the wave energy resource, which exceeded 10% in parts of the region, and the effect of waves on the calculation of the bottom stress, which was dominant in parts of the North Sea and Scotland, during an energetic wave period are presented, and some challenges are discussed. It was also shown that the model performance in the prediction of the wave parameters can improve by 25% in some places where the wave-tide interaction is significan

Experimental status of quaternionic quantum mechanics

Analysis of the logical foundations of quantum mechanics indicates the possibility of constructing a theory using quaternionic Hilbert spaces. Whether this mathematical structure reflects reality is a matter for experiment to decide. We review the only direct search for quaternionic quantum mechanics yet carried out and outline a recent proposal by the present authors to look for quaternionic effects in correlated multi-particle systems. We set out how such experiments might distinguish between the several quaternionic models proposed in the literature.Comment: 8 pages, no figures, revtex. An update of paper appearing in journal reference given below, with minor amendments and latest additional reference

Effect of waves on the tidal energy resource at a planned tidal stream array

Wave�current interaction (WCI) processes can potentially alter tidal currents, and consequently affect the tidal stream resource at wave exposed sites. In this research, a high resolution coupled wave-tide model of a proposed tidal stream array has been developed. We investigated the effect of WCI processes on the tidal resource of the site for typical dominant wave scenarios of the region. We have implemented a simplified method to include the effect of waves on bottom friction. The results show that as a consequence of the combined effects of the wave radiation stresses and enhanced bottom friction, the tidal energy resource can be reduced by up to 20% and 15%, for extreme and mean winter wave scenarios, respectively. Whilst this study assessed the impact for a site relatively exposed to waves, the magnitude of this effect is variable depending on the wave climate of a region, and is expected to be different, particularly, in sites which are more exposed to waves. Such effects can be investigated in detail in future studies using a similar procedure to that presented here. It was also shown that the wind generated currents due to wind shear stress can alter the distribution of this effect

Термопружний стан шаруватих термочутливих циліндрів і куль за конвективно-променевого теплообміну

Розроблено методику розв’язування одновимірних статичних задач термопружності для шаруватих циліндрів і куль за конвективно-променевого нагрівання з урахуванням лінійної залежності коефіцієнтів теплопровідності та довільного характеру залежності інших фізико-механічних характеристик від температури. Задачі теплопровідності зведено, незалежно від кількості шарів, до розв’язування системи двох нелінійних алгебричних рівнянь. У задачах термопружності неперервні в межах кожного шару коефіцієнти рівнянь апроксимовано кусково-сталими функціями. Проведено числовий аналіз температурних полів і напружень у двошарових тілах.The method for solving one-dimensional static thermoelasticity problems is developed for layered cylinders and spheres under convective and radiation heating, taking into account linear dependence of heat conductivity coefficients and arbitrary character of dependence of other physical and mechanical characteristics on a temperature. Problems of heat conductivity have been reduced to the system of two nonlinear algebraic equations regardless of the number of layers. In the thermoelasticity problems the continuous within every layer coefficients of equations are approximated by piecewise constant functions. The numerical analysis of the temperature fields and stresses is conducted for two-layered bodies.Разработана методика решения одномерных статических задач термоупругости для слоистых цилиндров и сфер при конвективно-лучевом нагреве с учетом линейной зависимости коэффициентов теплопроводности и произвольного характера зависимости других физико-механических характеристик от температуры. Задачи теплопроводности сведены, независимо от количества слоев, к решению системы двух нелинейных алгебраических уравнений. В задачах термоупругости непрерывные в пределах каждого слоя коэффициенты уравнений аппроксимированы кусочно-постоянными функциями. Проведен численный анализ температурных полей и напряжений в двухслойных телах

Распределение металлической фазы в синтетических алмазах типа «карбонадо»

Studying of a structural structure synthetic «carbonado» is spent by a method of electronic scanning microscopy. It is established, that the surface «carbonado» is covered by the large diamond crystals reaching 200 microns, having obviously expressed structure of growth. On a surface of these crystals observed drops of metal-catalyst (nickel) of a submicronic range. It is established, that the structure synthetic «carbonado» represents interpenetrating skeletons from diamond and ceramic-metal phases

Resonant Raman scattering off neutral quantum dots

Resonant inelastic (Raman) light scattering off neutral GaAs quantum dots which contain a mean number, N=42, of electron-hole pairs is computed. We find Raman amplitudes corresponding to strongly collective final states (charge-density excitations) of similar magnitude as the amplitudes related to weakly collective or single-particle excitations. As a function of the incident laser frequency or the magnetic field, they are rapidly varying amplitudes. It is argued that strong Raman peaks should come out in the spin-density channels, not related to valence-band mixing effects in the intermediate states.Comment: Accepted in Physical Review

Projecting the future: modelling Australian dialysis prevalence 2021–30

To project the prevalence of people receiving dialysis in Australia for 2021–30 to inform service planning and health policy. Methods. Estimates were based on data from 2011 to 2020 from the Australia & New Zealand Dialysis & Transplant (ANZDATA) Registry and the Australian Bureau of Statistics. We projected dialysis and functioning kidney transplant recipient populations for the years 2021–30. Discrete-time, non-homogenous Markov models were built on probabilities for transition between three mutually exclusive states (Dialysis, Functioning Transplant, Death), for five age groups. Two scenarios were employed – stable transplant rate vs a continued increase – to assess the impact of these scenarios on the projected prevalences. Results. Models projected a 22.5–30.4% growth in the dialysis population from 14 554 in 2020 to 17 829 (‘transplant growth’) – 18 973 (‘transplant stable’) by 2030. An additional 4983–6484 kidney transplant recipients were also projected by 2030. Dialysis incidence per population increased and dialysis prevalence growth exceeded population ageing in 40–59 and 60–69 year age groups. The greatest dialysis prevalence growth was seen among those aged ≥70 years. Conclusion. Modelling of the future prevalence of dialysis use highlights the increasing demand on services expected overall and especially by people aged ≥70 years. Appropriate funding and healthcare planning must meet this demand.Dominic Keuskamp, Christopher E. Davies, Georgina L. Irish, Shilpanjali Jesudason and Stephen P. McDonal

Small punch fatigue testing of a nickel superalloy

Miniaturised mechanical test approaches, specifically small punch testing, are now widely recognised as a means of obtaining useful mechanical properties to characterise the creep, tensile and fracture characteristics of numerous material systems from a range of industrial applications. Limited success has been found in replicating fatigue properties through the use of a small punch disc. This paper will discuss the ongoing research and progress in developing a novel small punch fatigue testing facility at the Institute of Structural Materials at Swansea University. Experiments have been performed on the nickel superalloy C263 at ambient room temperature, investigating three different alloy variants; two orientations produced through additive manufacturing and the cast equivalent. Fractographic analysis has been completed to interpret the complex damage mechanisms in the test method along with the differences in performance amongst the alloy variants