Performance of a single liquid column damper for the control of dynamic responses of a tension leg platform

Tuned liquid column dampers have been proved to be successful in mitigating the dynamic responses of civil infrastructure. There have been some recent applications of this concept on wind turbines and this passive control system can help to mitigate responses of offshore floating platforms and wave devices. The control of dynamic responses of these devices is important for reducing loads on structural elements and facilitating operations and maintenance (O&M) activities. This paper outlines the use of a tuned single liquid column damper for the control of a tension leg platform supported wind turbine. Theoretical studies were carried out and a scaled model was tested in a wave basin to assess the performance of the damper. The tests on the model presented in this paper correspond to a platform with a very low natural frequency for surge, sway and yaw motions. For practical purposes, it was not possible to tune the liquid damper exactly to this frequency. The consequent approach taken and the efficiency of such approach are presented in this paper. Responses to waves of a single frequency are investigated along with responses obtained from wave spectra characterising typical sea states. The extent of control is quantified using peak and root mean squared dynamic responses respectively. The tests present some guidelines and challenges for testing scaled devices in relation to including response control mechanisms. Additionally, the results provide a basis for dictating future research on tuned liquid column damper based control on floating platforms.

Chemical approaches for doping nanodevice architectures

Advanced doping technologies are key for the continued scaling of semiconductor devices and the maintenance of device performance beyond the 14 nm technology node. Due to limitations of conventional ion-beam implantation with thin body and 3D device geometries, techniques which allow precise control over dopant diffusion and concentration, in addition to excellent conformality on 3D device surfaces, are required. Spin-on doping has shown promise as a conventional technique for doping new materials, particularly through application with other dopant methods, but may not be suitable for conformal doping of nanostructures. Additionally, residues remain after most spin-on-doping processes which are often difficult to remove. In-situ doping of nanostructures is especially common for bottom-up grown nanostructures but problems associated with concentration gradients and morphology changes are commonly experienced. Monolayer doping (MLD) has been shown to satisfy the requirements for extended defect-free, conformal and controllable doping on many materials ranging from traditional silicon and germanium devices to emerging replacement materials such as III-V compounds but challenges still remain, especially with regard to metrology and surface chemistry at such small feature sizes. This article summarises and critically assesses developments over the last number of years regarding the application of gas and solution phase techniques to dope silicon-, germanium- and III-V-based materials and nanostructures to obtain shallow diffusion depths coupled with high carrier concentrations and abrupt junctions.

Portfolio of compositions with commentaries 2012-2015

This writing forms part of a portfolio of works which gathers together notations and recordings made between 2012 and 2015. The writing divides into four chapters. The first chapter undertakes an examination of abstraction. From the proposition obtained therein, that it is possible to extend within abstraction beyond a correspondence between its terms and concrete manifestations, I ask in what way abstraction may be considered to function therefrom. The second chapter performs an analysis of radical music notations from the nineteenth, twentieth, and twenty-first centuries. The central analysis identifies what is essentially an evolution of what I call ''figuration'' throughout three non-chronological phases of Christian Wolff's notations. The chapter closes by questioning what form of understanding might yet be pursued in respect of this work given (a) its nature, and (b) the nature of our inquiry. The third chapter reflects on some of the philosophical problematics raised in the preceding chapters, at the same time as it prepares for those that follow in the final chapter. The final chapter is a record of the development of my thought appertaining to my compositional work. It sets out two case studies (prepared piano and postcard notations) before proceeding to a selected set of commentaries. Finally, the notion of the functioning of written and acoustical ''marks'' developed in the preceding commentaries is generalised as I develop an aesthetics of scriptural experience.