Water wave transmission by an array of floating disks

An experimental validation of theoretical models of transmission of regular water waves by large arrays of floating disks is presented. The experiments are conducted in a wave basin. The models are based on combined potential-flow and thin-plate theories, and the assumption of linear motions. A low-concentration array, in which disks are separated by approximately a disk diameter in equilibrium, and a high-concentration array, in which adjacent disks are almost touching in equilibrium, are used for the experiments. The proportion of incident wave energy transmitted by the disks is presented as a function of wave period, and for different wave amplitudes. Results indicate that the models predict wave energy transmission accurately for small-amplitude waves and low-concentration arrays. Discrepancies for large-amplitude waves and high-concentration arrays are attributed to wave overwash of the disks and collisions between disks. Validation of model predictions of rigid-body motions of a solitary disk are also presented

Reflection and transmission of ocean wave spectra by a band of randomly distributed ice floes

A new ocean wave/sea-ice interaction model is proposed that simulates how a directional wave spectrum evolves as it travels through an arbitrary finite array of circular ice floes, where wave/ice dynamics are entirely governed by wave scattering effects. The model is applied to characterise the wave reflection and transmission properties of a strip of ice floes, such as an ice edge band. A method is devised to extract the reflected and transmitted directional wave spectra produced by the array. The method builds upon an integral mapping from polar to Cartesian coordinates of the scattered wave components. Sensitivity tests are conducted for a row of floes randomly perturbed from a regular arrangement. Results for random arrays are generated using ensemble averaging. A realistic ice edge band is then reconstructed from field experiments data. Simulations show a good qualitative agreement with the data in terms of transmitted wave energy and directional spreading. In particular, it is observed that short waves become isotropic quickly after penetrating the ice field

An idealised wave-ice interaction model without subgrid spatial and temporal discretisations

A modified version of the wave-ice interaction model proposed by Williams et al (2013a,b) is presented for an idealised transect geometry. Wave attenuation due to ice floes and wave-induced ice fracture are both included in the wave-ice interaction model. Subgrid spatial and temporal discretisations are not required in the modified version of the model, thereby facilitating its future integration into large-scaled coupled models. Results produced by the new model are compared to results produced by the original model of Williams et al (2013b).Comment: 8 pages, 3 figure

Lilac tractors : a novel ; and, Critical essay: intersections among psychiatry, madness, sexuality and feminism in \u27Lilac tractors\u27

This thesis comprises a novel, ‘Lilac Tractors’ and an essay, ‘Intersections among psychiatry, madness, sexuality and feminism in ‘Lilac Tractors’’. The novel focuses on the relationship of a married couple, Gary, a fly-in, fly-out rig worker, and Sharon, a mature-age university student studying psychology. They live together in Perth’s north at the turn of the twenty-first century, as the outer suburbs are beginning to sprawl. Gary has Obsessive Compulsive Disorder (OCD) and Sharon finds that her growing knowledge of the condition increases her annoyance with him, rather than her compassion. But mostly she is unhappy because Gary is too gentle and the relationship doesn’t provide the power differentiation she requires to feel sexually fulfilled. The novel explores the intersection between his psychiatric condition and their domestic lives while also investigating intergenerational relationships of mothers, fathers, sons and daughters, and complicated forms of inheritance. Various themes are explored in the novel, including the overarching idea that, in patriarchal societies, there is a common tendency towards control of that which is different or perceived as threatening: women, the mentally ill and the land. This is explored through the juxtaposition of masochistic sexual desire, psychosurgical treatment and the tractors that clear the land next door to Sharon and Gary’s house. The tractors provide a visual reminder of one way that humankind controls the environment. The critical essay discusses the inspiration for and genesis of ’Lilac Tractors’, which was developed first as a film script and progressed through many versions to become a novel. I discuss my stylistic choices and why I chose to write a work of general fiction that draws on and also violates some key conventions of ‘chick lit’. The essay also refers to relevant feminist theory and criticism to support a discussion on pornography and female sexuality, providing an explanation and rationale for the novel’s depiction of a masochistic relationship. ‘Lilac Tractors’ depicts ‘aberrant sexuality’ within a conventional suburban milieu, which some readers may find challenging or even iv troubling; however, fictional treatments of this kind are important and might potentially open space for frank and serious examination of power in relation to sexual desire. A key concern of the novel is psychiatry. The essay also discusses two aspects of psychiatry, with a focus in particular on the history and practice of psychosurgery and diagnostic and literary depictions of Obsessive Compulsive Disorder

A steady-state magneto-optical trap with 100 fold improved phase-space density

We demonstrate a continuously loaded $^{88}\mathrm{Sr}$ magneto-optical trap (MOT) with a steady-state phase-space density of $1.3(2) \times 10^{-3}$. This is two orders of magnitude higher than reported in previous steady-state MOTs. Our approach is to flow atoms through a series of spatially separated laser cooling stages before capturing them in a MOT operated on the 7.4-kHz linewidth Sr intercombination line using a hybrid slower+MOT configuration. We also demonstrate producing a Bose-Einstein condensate at the MOT location, despite the presence of laser cooling light on resonance with the 30-MHz linewidth transition used to initially slow atoms in a separate chamber. Our steady-state high phase-space density MOT is an excellent starting point for a continuous atom laser and dead-time free atom interferometers or clocks.Comment: 11 pages, 5 figure