Digital Commons Network^™

A New Algorithm For Piecewise Affine System Identification And Its Application To A Mems Switch, Niel Canty

Theses

Over the past ten years, hybrid systems, and piecewise affine (PWA) systems in particular have been viewed as viable option for modelling nonlinear systems. Many methods have been developed to cater for the identification of a PWA model from input/output data. This thesis focuses on the clustering based identification approach. This method uses a Least Squares (LS) identification algorithm which, in this thesis, is shown to perform poorly in practice. The clustering based algorithm is also limited by the number of initialisation parameters that need to be chosen. These parameters have a significant influence on the resulting PWA model accuracy, …

Examining Student Severe Weather Behavior During A Hypothetical Tornado Scenario, C Martin Leavitt

Theses

No abstract provided.

A Study Of Density Fluctuations For Flow Over A Flat Plate Using A Hybrid Reynolds-Average Navier-Stokes Large Eddy/Simulation Approach, John Price

Theses

The objective of this thesis is to study the density fluctuations due to turbulent flow structures generated within a spatially developing boundary layer using a hybrid Reynolds-Averaged Navier-Stokes/Large Eddy Simulation approach. For this study, a flat plat configuration was used. A planar mixing inflow boundary condition was used to add large-scale fluctuations to the flow field. Computations were performed using the Wind-US 3.0 computational fluid dynamics code and the Nichols/Nelson multiscale hybrid RANS/LES approach as implemented in the Wind-US code [7]. The study showed that the normalized density profile normal to the flat plate is sensitive to spanwise grid spacing, …

Three-Dimensional Model Of A Plasma Railgun Using Smoothed Particle Hydrodynamics, Lloyd M. Jackson

Theses

Pulsed plasma accelerators are utilized for in-space propulsion and drivers for inertial fusion concepts. Theoretical models are necessary to assist in diagnostic analysis and for developing scaling laws. SPFMax is a new 3D code which uses smoothed particle hydrodynamics (SPH) to simulate fluid flow, and has been designed specifically for modeling plasmas produced by these pulsed devices. A set of gasdynamic test cases were established and utilized to verify the accuracy of SPFMax for modeling the gas dynamics in a railgun. The free expansion confirmed that the gas expands supersonically without exceeding the predicted maximum value. With the square wave …

Factors That Contribute To The Establishment Of Marine Protected Areas In Western Australia, Andrew Hill

Theses

Five Marine Protected Area (MPA) establishment processes undertaken between 1998 and 2012 in Western Australia were reviewed using a case study approach to identify factors affecting establishment. While three MPAs were legally created, two were not, despite significant investment in planning, research and public participation. Processes were generally influenced by complex local and strategic planning issues that were significant barriers to legal establishment.

Planning and public participation processes were generally successful at addressing local concerns, deriving consensus and building ownership but ineffectual at addressing key strategic issues. MPA establishment was primarily influenced by the social, economic and political influences rather …

Analysis Of The Current Public Relations Practices Within The Irish Luxury Hotel Sector And The Importance Of These Practices To The Industry., Aoife Ducatta Lohse

Theses

The purpose of this study was to investigate the current knowledge, importance and application of public relations within Irish Luxury Hotels. Another aim was to find out how the public relations theories of relationship management, strategic management and communications are used in the sector.

The research methodology in this study used a mixed method approach. Quantitative research was used in the form of an online questionnaire and qualitative research was used in the form of semi-structured interviews. The online questionnaire was distributed to all luxury four star and five star properties with an online presence in Ireland with an aim …

A Decision Making Tool For Sustainable Design In Construction, Enda Collins

Theses

This report defines sustainability and sustainable development before any research is carried out. This is necessary so that the research carried out further in the report makes sense and there is a reason for including such items in this report. The need for this project and what the project aims to achieve is also highlighted in the introduction of this report.

Sustainability is made up of three equal parts; social, economic and environmental. This report goes through each item and gives examples of each type of development. Having discussed sustainability in a broad sense the report then focuses on Legislation …

A Novel Waveform For Emergency Services Mobile Ad-Hoc Networks : The Link Layer Perspective, Sebastian Helmle

Theses

Existing wireless communication systems of emergency services mainly enable ordinary unicast or broadcast voice communications. The increasing demand for data services such as messaging, file transfer, maps, etc requires those long-range communication systems to provide higher data rates while maintaining robustness against link failures. In this thesis, various aspects of a link layer design specifically for narrowband mobile ad-hoc networks (MANETs) that are targeted at emergency services are investigated.

The major aspect of this thesis is the optimisation of a time division multiple access (TDMA) design considering both efficient and reliable multicast resource reservation. An approach to mathematically describe a …

Achieving ‘Net Zero Energy’ Performance Through Retrofitting Of Residential Buildings In Ireland., M. Alan Costello

Theses

A Net Zero Energy Building (nZEB) is a residential or commercial building that consumes net zero energy over a set period of time, usually taken as one year. In short, for every unit of energy the building consumes over a year, it must generate a unit of energy to maintain an overall net balance. This is achieved by reducing the operational energy usage to a very low level through energy efficient design, and then providing renewable generation technologies on site to cater for the remaining energy demand.

Energy use in all sectors of society is under scrutiny at present, largely …

Investigation Of Pyrrolizidine Alkaloids In Foods Using Liquid Chromatography Mass Spectrometry, Caroline Griffin

Theses

Pyrrolizidine Alkaloids (PAs) are known plant toxins which can cause hepatic veno-occlusive disease (HVOD) in both humans and livestock when ingested. Although PAs are primarily known for their hepatotoxicity they also induce genotoxicity, carcinogenicity and pneumotoxicity. PAs are consumed through plants as food, for medicinal purposes, or as contaminants of agricultural crops. Aside from ingesting the plants directly PA exposure may occur through the consumption of honey produced by bees that visit PA-containing plants or by drinking milk produced by animals that have consumed PA-containing plants. Possible PA contamination in our food chain is a potential health risk.

To assess …

The Development Of Liquid Chromatography Mass Spectrometry Methods For The Analysis Of Cyanobacterial Toxins In Environmental Freshwaters, Brian Anthony Dineen

Theses

Cyanobacteria, also known as blue-green algae, are a common component of many freshwater and marine ecosystems and have a potential to produce several different classes of biotoxins. The most common class of cyanobacterial toxins are the microcystins (MCs) and cylindrospermopsins (CYLs). MCs are cyclic heptapeptides that display potent hepatotoxicity and are tumour promoters. CYLs are alkaloids that are cytotoxic and can cause illness and display hepatotoxic effects in animals and humans. Worldwide, these toxins have caused fatal poisonings to animals, birds and fish. Several incidents of human intoxications have been reported and the presence of these toxins in environmental waters …

Perceptions Of Leaders, Teachers, Students And Parents In High Performing West Australian Catholic Secondary Schools Within The Context Of Tertiary Entrance Examinations, Michael O'Neill

Theses

As for most of the developed world, Australia is no different in its scrupulous evaluation of school performance data. Annually much attention is given to data surrounding the performance of students, teachers and schools in high stakes Tertiary Entrance Examinations as students seek to qualify for a variety of university programs. So called ‘league tables’ are produced measuring school performance on a number of criteria which differ marginally from state to state. Such tables identify both successful and less successful schools. Notwithstanding the limitations of such comparisons and the fact that success is a relative term there is a great …

Focal Stacking Of Microscopic Images Using Modified Harris Corner Response Measure, Madhu Sudan Sigdel

Theses

Automated image analysis of microscopic images such as protein crystallization images and cellular images is one of the important research areas. For proper analysis of the microscopic images, it is necessary to have images where all objects are in good focus. If objects in a scene (or specimen) appear at different depths with respect to the camera's focal point, objects outside the depth of field usually appear blurred. It is not possible to get all objects in focus simultaneously by changing the focal point of a lens of camera. Therefore, scientists capture a collection of images with different depths of …

Twisting Algorithm For Controlling F-16 Aircraft With Performance Margins Identification, Akshay Kulkarni

Theses

A Twisting algorithm based second order sliding mode controller is designed for tracking of command angles for nonlinear flight dynamics of an F-16 aircraft, before and after the battle damages. The high frequency switching controller is designed in terms of control derivative so that the actual control function is continuous. The practical robustness performance margins are identified in terms of maximal additional gain (Practical Gain Margin) and phase lag (Practical Phase Margin) added to the frequency characteristic of the linear part of the open loop system that yield acceptable loss of command angle tracking performance in terms of admissible parameters …

Software Component Metadata For Selecting And Verifying Model Compositions In Semi-Automated Forces Systems, Konstantinos Prapiadis

Theses

Research into a framework or methodology able to facilitate the integration or composition of existing software components into a new software system has a long history, both in software engineering in general and in modeling and simulation in particular. The potential benefits from the reuse of previously developed software components are well-known; they include reduction in both the cost and the time needed to develop a new system. In this thesis a methodology for the implementation of new simulation software systems using previously developed software components is developed and tested. The methodology is focused on semi-automated forces systems, an important …

Analysis Of Bi-Directional Reflectance Distribution Functions Of Structured Rough Surfaces, Amanda Black Clark

Theses

Details of experimental and modeled Bi-directional Reflectance Distribution Functions (BRDFs) for rough aluminum surfaces are contained in this document. High energy lasers are of interest to the military for intersepting incoming threats. An issue with using high energy lasers in this way is that reflectance from the threat surface can irradiate objects not in the direct path of the laser and cause damage. BRDFs can be used to propagate reflected energy in any given geometrical scenario to determine irradiance on areas of interest. A gonioreflectometer was used to collect reflectance data from 6061 aluminum alloy sanded and structured machined samples. …

Efficient Particle-In-Cell Simulation Of Auroral Plasma Phenomena Using A Cuda Enabled Graphics Processing Unit, Stephen Sewell

Theses

This thesis introduces a software framework that effectively utilizes low-cost commercially available Graphic Processing Units (GPUs) to simulate complex scientific plasma phenomena that are modeled using the Particle-In-Cell (PIC) paradigm. The software framework that was developed conforms to the Compute Unified Device Architecture (CUDA), a standard for general purpose graphic processing that was introduced by NVIDIA Corporation. This framework has been verified for correctness and applied to advance the state of understanding of the electromagnetic aspects of the development of the Aurora Borealis and Aurora Australis. For each phase of the PIC methodology, this research has identified one or more …

Design Of Experiment To Analyze Effect Of Input Parameters On Thermal Stress And Deformation In Overhanging Part Features Created With The Slm Additive Manufacturing Process, Albert E. Patterson V

Theses

Selective laser melting (SLM) is a very advanced and promising additive manufacturing process which is beginning to take root in the US manufacturing scene. Unfortunately, it is not fully developed as of yet and still suffers from problems; the most serious of these is the tendency of the process to trap residual stresses within the parts during the process. Overhanging and delicate features suffer particularly from this. A full-factorial experiment was designed and performed as a tool to explore this problem and provide insight into ways to deal with this problem in engineering design. The experiment utilized a simple simulation …

Incorporating Size Effect Into A Micromechanical Model For Brittle Materials, Wm. Patrick Roush

Theses

This research addresses computational modeling of the size effect in brittle materials, a phenomenon commonly seen in laboratory tests but has not been adequately accounted for in computational models for such materials. Size effect is accounted for in this research by extending a damage model for brittle materials (the DCA model), which is based on the consideration of micromechanics of defects in the materials. In particular, the statistical distribution of the defects in a brittle material is assumed to vary with the size of the material sample under consideration. The idea has been numerically implemented in the DCA model and …

Analytic Model To Estimate Thermonuclear Neutron Yield In Z-Pinches Using The Magnetic Noh Problem, Rachael Agnew

Theses

The objective was to build a model which could be used to estimate neutron yield in pulsed z-pinch experiments, benchmark future z-pinch simulation tools and to assist scaling for breakeven systems. To accomplish this, a recent solution to the magnetic Noh problem was utilized which incorporates a self-similar solution with cylindrical symmetry and azimuthal magnetic field (Velikovich, 2012). The self-similar solution provides the conditions needed to calculate the time dependent implosion dynamics from which batch burn is assumed and used to calculate neutron yield. The solution to the model is presented. The ion densities and time scales fix the initial …

Modal Analysis And Acoustic Transmission Through Offset-Core Honeycomb Sandwich Panels, Adam Dustin Mathias

Theses

The work presented in this thesis is motivated by an earlier research that showed that double, offset-core honeycomb sandwich panels increased thermal resistance and, hence, decreased heat transfer through the panels. This result lead to the hypothesis that these panels could be used for acoustic insulation. Using commercial finite element modeling software, COMSOL Multiphysics, the acoustical properties, specifically the transmission loss across a variety of offset-core honeycomb sandwich panels, is studied for the case of a plane acoustic wave impacting the panel at normal incidence. The transmission loss results are compared with those of single-core honeycomb panels with the same …

Transverse And Compressional Hydromagnetic Waves In The Earth's Magnetosphere, Jinlei Zheng

Theses

Hydromagnetic waves, especially those of frequencies in the range of a few milli-Hz to a few Hz observed in the Earth's magnetosphere, are categorized as Ultra Low Frequency (ULF) waves or pulsations. They have been extensively studied due to their importance in the interaction with radiation belt particles and in probing the structures of the magnetosphere. We developed an approach in examining the toroidal (transverse) standing Alfvén waves in a background magnetic field by recasting the wave equation into a Klein-Gordon (KG) form along individual field lines. The eigenvalue solutions to the system are characteristic of a propagation type when …

Fabrication And Characterization Of Thermoelectric Nanolayer Thin Films Modified By Mev Si Ions, Muhammed E. Gulduren

Theses

Thermoelectric generators convert heat to electricity. A low thermal and a high electrical conductivity are characteristics of thermoelectric materials and devices. The efficiency of thermoelectric materials and devices is quantified by dimensionless figure of merit ZT=TS^2&sigma/&kappa where S is the Seebeck coefficient, &sigma is the electrical conductivity, T is the absolute temperature in Kelvin, and &kappa is the thermal conductivity. Multilayer thin films with 100 alternating layers of SiO2/SiO2+Ge, 50 alternating layers of Si/Si+Sb, and 40 alternating layers of Si/Si+Ge superlattice thin films have been prepared by using ion beam-assisted deposition (IBAD) and DC/RF Sputtering in order to study thermoelectric …

Modeling Stock Return Volatility In Mongolian Stock Market, Munkhtsog Altankhuu

Theses

This paper is one of the first research works to examine the stock index volatility in the Mongolian Stock Exchange. The study utilizes the Generalized Autoregressive Conditional Heteroscedasticity (GAR CH) models to estimate volatility of stock market return of the Mongolian Stock Exchange. A number of prior research work demonstrated that ARCH and GARCH models are fruitful models for modeling volatility of time series data. However, they recommend using different versions of GARCH-type models for different distributions (Normal, Student's t, Skewed Student's t and Generalized Error Distribution) for emerging markets or developing markets. This paper compares the GARCH(l, 1) model …

The "Globesity" Trend: Exploring The Ethical Concerns Of Registered Nurses Caring For Bariatric Surgery Patients, Casey L. Lowden-Crook

Theses

Obesity is a major global health problem. The comorbidities associated with obesity (for example: diabetes mellitus type 2 and cardiovascular disease) are multisystem and require continual medical management which places a great strain on the healthcare system. Australia is ranked the 5th most obese population in the world and deaths associated with obesity and obesity related illnesses are estimated at 7,200 per year (Medibank, 2010). This lifestyle disease is now the leading cause of premature death in Australia. The obesity epidemic is blamed on changes in the social, economic and physical environment (obesogenic environments) which have influenced people to over-consume …

Multiple Intelligences And Therapeutic Alliances: Counsellors' Experiences Of Incorporating A Multiple Intelligence Approach To Counselling, Mark Pearson

Theses

Counselling clients display many ways of reflecting and communicating within therapy. Gardner’s theory of multiple intelligences (MI), while applied widely in the field of education, has only recently been applied to the field of counselling, and has the potential to support flexible responses to client’s different styles. In this study, counsellor experiences with introducing a MI approach to counselling are investigated. A focus on the impact of MI on therapeutic alliances is highlighted as therapeutic connection has been shown to contribute significantly to positive therapy outcomes. Recent research highlights the positive impact from modifying treatment in response to individual client …

Heat Misconceptions Among 11th Grade Students, Amnah Mohamed Abdullah Al Kaabi

Theses

This study explores the misconception of the female students at 11^thgrade about the heat concepts (e.g., latency, conduction, equilibrium, boiling point, etc.) the study targets to i – classifying the misconception nature, and ii- distinguishing the heat misconception from point of the lack of knowledge and lucky guess. A sample of 230 female students at 11^th grade randomly selected from five secondary schools in the Emirates of Fujairah; northern UAE. The heat misconception test (HMT), a three –tier diagnostic instrument comprising of ten question is used as data collection tool. The study raises the three research questions. …

Discovering Real-World Usage Scenarios For A Multimodal Math Search Interface, Keita Del Valle Wangari

Theses

To use math expressions in search, current search engines require knowing expression names or using a structure editor or string encoding (e.g., LaTeX) to enter expressions. This is unfortunate for people who are not math experts, as this can lead to an "intention gap" between the math query they wish to express, and what the interface will allow. m_in is a search interface that supports drawing expressions on a canvas using a mouse/touch, keyboard and images. We designed a user study to examine how the multimodal interface of m_in changes search behavior for mathematical non-experts, and discover real-world …

Feed Rate Effects In Freeform Filament Extrusion, Omkar Rishi

Theses

3D printing technologies have evolved drastically in the last decade. Professional grade 3D printers produce very high quality parts largely because they have been optimized for use with just a few different materials and do not allow the user to change process parameters. Conversely, Freeform Filament Extrusion (FFE) is a technology that has emerged as a favorite of hobbyists due to widespread availability of low cost open architecture machines that permit extensive experimentation with any number of materials. The FFE 3D printing process operates by feeding thermoplastic filament through a heated nozzle while the nozzle "draws" the desired pattern one …

Using Delay-Differential Equations For Modeling Calcium Cycling In Cardiac Myocytes, Ryan Thompson

Theses

The cycling of calcium at the intracellular level of cardiac cells plays a key role in the excitation-contraction process. The interplay between ionic currents, buffering agents, and calcium release from the sarcoplasmic reticulum (SR) is a complex system that has been shown experimentally to exhibit complex dynamics including period-2 states (alternans) and higher-order rhythms. Many of the calcium cycling activities involve the sensing, binding, or diffusion of calcium between intracellular compartments; these are physical processes that take time and typically are modeled by “relaxation” equations where the steady-state value and time course of a particular variable are specified through an …