Conditional Wasserstein generative adversarial networks applied to acoustic metamaterial design

This work presents a method for the reduction of the total scattering cross section (TSCS) for a planar configuration of cylinders by means of generative modeling and deep learning. Currently, the minimization of TSCS requires repeated forward modelling at considerable computer resources, whereas deep learning can do this more efficiently. The conditional Wasserstein generative adversarial networks (cWGANs) model is proposed for minimization of TSCS in two dimensions by combining Wasserstein generative adversarial networks with convolutional neural networks to simulate TSCS of configuration of rigid scatterers. The proposed cWGAN model is enhanced by adding to it a coordinate convolution (CoordConv) layer. For a given number of cylinders, the cWGAN model generates images of 2D configurations of cylinders that minimize the TSCS. The proposed generative model is illustrated with examples for planar uniform configurations of rigid cylinders

Oscillating Foil Propulsion

In this thesis, an investigation on the use of oscillating foil propulsion for marine vehicle as an alternate effective propulsion system is presented. Three different oscillating foil propellers, namely: two-dimensional oscillating foil propeller; flexible fin propeller, and rotary foil propeller, have been studied. The thesis is made up of four parts: one related to each type of propeller and one on the application of oscillating foil propellers along with general conclusions. Two-Dimensional Oscillating Foil Propeller A review on the hydrodynamic forces and moments acting on a two-dimensional oscillating foil is presented. The equations for estimating the force system have been extended to cover different phase lags between heave and pitch and to calculate the force system at a particular instant of time within an oscillating cycle. The sensitivity of the propulsive thrust coefficient and the hydromechanical efficiency has been investigated for a range of different parameters. The operating condition for optimum performance is identified. Flexible Fin Propeller The theoretical model of the flexible fin propeller, which has been set up by combining linearised unsteady foil theory and large deflection beam theory, is described. Non-dimensional parameters are established to study the performance of this type of propeller. A flexible fin propeller model and its test rig was designed and built. The model was tested in the Hydrodynamics Laboratory at the Department of Naval Architecture and Ocean Engineering, the University of Glasgow. The performance of the propeller was examined at both forward and zero speeds. Results have been compared with theoretical predictions. Conclusions on the performance of the flexible fin propeller are drawn based on the theoretical predictions and experimental results. The stress acting on the flexible bar has been computed and discussed. The selection of material has been discussed and promising materials identified. The feasibility of using flexible fin propellers for wave propulsion to absorb wave energy and convert it into propulsive thrust has been studied. A one-fifth scale model of a three quarter ton racing yacht with a flexible fin propeller model mounted at the stem was tested. At a low Froude number, there is a significant reduction in the motion response and in the required thrust around the resonance zone, where the encounter wave length is equal to the ship length. Rotary Foil Propeller A three bladed propeller model with high-aspect ratio blades was tested in forward and reverse directions and zero speed conditions. The experimental results on the performance of the model at forward speed have been compared to that predicted by Bose [1987] using multiple stream tube theory and discussed. Application of Oscillating Foil Propeller and General Conclusions The practical application of three oscillating foil propellers and economic studies of their operation have been studied and discussed. Three ship examples with the same Froude number but different in sizes and a high speed craft have been used in these studies. Three types of oscillating foil propeller are designed for each ship example. The required stem hull form and the driving mechanism have been discussed. The application of the flexible fin propeller in wave propulsion has been demonstrated. The natural frequency of a full scale flexible fin propeller was calculated and found to be much higher than the optimum driving frequencies in the operating condition. The net present value method has been applied in the economic studies where breakeven conditions, different interest rates, fluctuation of oil price, and different additional maintenance costs have been considered. The main conclusions of this research have been drawn up and are presented. Recommendation on the design of these propeller are also made

Dynamics of confined water reconstructed from inelastic x-ray scattering measurements of bulk response functions

Nanoconfined water and surface-structured water impacts a broad range of fields. For water confined between hydrophilic surfaces, measurements and simulations have shown conflicting results ranging from “liquidlike” to “solidlike” behavior, from bulklike water viscosity to viscosity orders of magnitude higher. Here, we investigate how a homogeneous fluid behaves under nanoconfinement using its bulk response function: The Green's function of water extracted from a library of S(q,ω) inelastic x-ray scattering data is used to make femtosecond movies of nanoconfined water. Between two confining surfaces, the structure undergoes drastic changes as a function of surface separation. For surface separations of ≈9 Å, although the surface-associated hydration layers are highly deformed, they are separated by a layer of bulklike water. For separations of ≈6 Å, the two surface-associated hydration layers are forced to reconstruct into a single layer that modulates between localized “frozen’ and delocalized “melted” structures due to interference of density fields. These results potentially reconcile recent conflicting experiments. Importantly, we find a different delocalized wetting regime for nanoconfined water between surfaces with high spatial frequency charge densities, where water is organized into delocalized hydration layers instead of localized hydration shells, and are strongly resistant to `freezing' down to molecular distances (<6 Å)

Defining Classical Tenor Saxophone: performer identity, performance practice and contemporary repertoire

The tenor saxophone has gained prominence as a classical instrument for composers and performers during the last four decades. Interest in the instrument has inspired the creation of innovative works and tenor saxophonists are charged with preparing these works for performance. Performing new repertoire has impacted the way in which the classical tenor saxophonists explore the musical potential of their instrument and their role in a larger sense. The aim of this study is to identify important works in the contemporary classical tenor saxophone repertoire, establish how performers approach these works, and discover their perceptions of the instrument. Twenty-two professional saxophonists from Australia, Europe, the United Kingdom and the United States of America completed a questionnaire in which they identified significant contemporary classical tenor saxophone works and explained why the works were important to the instrument’s modern repertoire. Twelve saxophonists then participated in an interview in which they explored their perceptions of classical tenor saxophone performance, and gave insights into their experiences studying, performing and teaching the most significant repertoire. Three key works written between 1986 and 2011 were identified, all of which utilised the tenor saxophone’s extensive musical and technical capabilities. These works were all written in a contemporary style and featured strong influences from jazz/pop music. Saxophonists regarded the tenor saxophone as a versatile instrument remarkably suited to the classical idiom and unique in the saxophone family. These professionals employed novel technical and musical approaches in their performance of the contemporary tenor saxophone repertoire to create successful and authentic interpretations. They explained their common perceptions of the instrument and shared a collective musical identity as classical tenor saxophonists

An Olfactory Receptor Pseudogene whose Function emerged in Humans

Human olfactory receptor, hOR17-210, is identified as a pseudogene in the human genome. Experimental data has shown however, that the gene product of cloned hOR17-210 cDNA was able to bind an odorant-binding protein and is narrowly tuned for excitation by cyclic ketones. Supported by experimental results, we used the bioinformatics methods of sequence analysis, computational protein modeling and docking, to show that functionality in this receptor is retained due to sequence-structure features not previously observed in mammalian ORs. This receptor does not possess the first two transmembrane helical domains (of seven typically seen in GPCRs). It however, possesses an additional TM that has not been observed in other human olfactory receptors. By incorporating these novel structural features, we created two putative models for this receptor. We also docked odor ligands that were experimentally shown to bind hOR17-210 model. We show how and why structural modifications of OR17-210 do not hinder this receptor&#x27;s functionality. Our studies reveal that novel gene rearrangement that result in sequence and structural diversity in has a bearing on OR and GPCR function and evolution