Applied Mechanics Commons^™

Development Of A Dynamic Cfd Model For Offshore Oscillating Water Columns With Non-Linear Interactions, Ken O'Connell

Theses

This thesis focuses on the development of a state of the art modelling technique for offshore Oscillating Water Column (OWC) type Wave Energy Converters (WEC) using Computational Fluid Dynamics (CFD). Current literature indicates a limited amount of work has been completed on studying these devices containing non-linear time dependent flow phenomenon. Initially, a 2D Numerical Wave Tank (NWT) is studied to reduce discretisation error in order to reproduce accurately propagating waves. Further development into a 3D domain permits the geometrical requirements of an OWC type spar buoy to be included.

In parallel, a single Degree of Freedom (DOF) model is …

Carbon Dioxide Absorption And Channelling In Closed Circuit Rebreather Scrubbers, Shona Cunningham

Theses

Closed Circuit Rebreathers (CCRs) are a type of Self Contained Underwater Breathing Apparatus (SCUBA) used predominantly by the diving community. CCR technologies have become prevalent within the commercial, military and technical diving communities over recent years. CCRs work by recycling breathing gas, by-passing the gas through a carbon dioxide (CO₂) chemical scrubber and topping the resultant scrubbed gas up with pure oxygen to maintain the oxygen content at a level which supports life. One of the main dangers currently faced by divers using this equipment is the risk of CO₂ poisoning if the scrubber fails. This failure …

The Design And Development Of A Substitution Device For The Visually Impaired., Kieran John O'Callaghan

Theses

Current sensory substitution systems for the visually impaired are limited in terms of their spatial and depth resolution capabilities. They are unable to relay real-time 3D spatial information regarding objects in the direct path of the user. Recent advances in 3D imaging technology have presented new opportunities to develop improved sensory substitution systems to compensate for visual sensory loss. The present study established the design criteria, designed, manufactured and evaluated the performance of a real-time vision substitution device called VisionRE.

Knowledge obtained from a literature review of Human Machine Interfaces (HMIs), feedback from visually impaired focus groups and 3D electrode …

Design Of A Smart System For Monitoring Concrete Curing And Structural Health, William Quinn

Theses

Structural Health Monitoring (SHM) is a rapidly growing sector of the construction industry. Automated monitoring methods arc mainly limited to global monitoring and the application of local monitoring methods has not gained widespread application due to the fact that currently technology requires that the systems are wired to data acquisition devices. This thesis presents a fully embeddable wireless sensor node for the local monitoring of structural concrete. It presents the first reported wireless embedded system implementation of the electromechanical impedance method using both resonant and antiresonant sensors for this purpose.

The first section of this thesis examines the feasibility of …

An Investigation On The Dynamic Behavior Of An Overhead Valve Actuating Mechanism, Michael Noonan

Theses

This project involves the measurement and simulation of the dynamic performance of a pushrod valvetrain, in particular that of the outer valve spring. The engine was donated by S&S Cycle Wisconsin. A motoring test rig was constructed to obtain high speed camera footage of the spring coils motion. Individual static spring coil displacement measurements were taken, and their stiffness studied. Spring and pushrod natural resonant frequencies were measured. All data acquisition and analysis was carried out with Labview programs written during the project. Programs were written to model individual static coil stiffness using the close coil, open coil, and theories …

System Identification Of A Pasteurisation Process: A Comparison Of Direct And Indirect Methods, Niel Canty

Theses

The primary focus of this research is to identify a linear model for a direct steam injection (DSI) pasteurisation process which is a component of a large-scale pilot evaporation process widely used in the dairy industry. The pasteurisation process has been identified as a key component of the evaporation process. The author believes that no previously published work has focused on identifying models for a DSI pasteurisation process which makes this work an original contribution to the area. The pasteurisation process can be modelled as a single-input, single-output (SISO) process with a measurable disturbance. Thus two transfer functions were required …

Analytical And Fea Analysis Of Silicon Micro-Machined Capacitive Pressure Sensor, Eoghan O'Donoghue

Theses

This thesis is concerned with the electro-mechanical characterisation of MEMS capacitive pressure sensors and the determination of models to describe their behaviour.

The finite element software package ANSYS is validated as a tool for the examination of the electro-mechanical behaviour of capacitive pressure sensors. It is then used to incorporate the effects of applied load, voltage and residual stress into a model of the sensor structure. The capacitive pressure sensor is modelled both in 3D and also in 2D axis-symmetric modes. The error between the 2D and 3D models is quantified.

The behaviour of structures under electrostatic actuation is investigated. …

Virtual Reality Modelling Of A Cnc Machine, Damian O'Sullivan

Theses

The increasing importance of training and upgrading skills has led to the use of new interactive technologies in the development of more effective training tools. Previous techniques for training Computer Numerical Control (CNC) machine operators, while excellent for their time, varied from brief inexpensive tutorials to expensive on the job training. A CNC machine uses a computer to perform the functions of the machine using a part program stored in the memory of the computer. This thesis describes a Virtual Reality (VR) model of a CNC milling machine, implemented within a VR environment representing a CNC workshop. Its development and …

An Investigation Using The Finite Element Method Into Bowing & Lean Of The 3rd Stage Turbine Blade Of The Pratt & Whitney Jt8d Gas Turbine Engine, Kevin O'Donoghue

Theses

Following a recent series of failures of overhauled third stage turbine blades in the JT8D- 15A gas turbine engine, new inspection criteria have been introduced by the engine manufacturer Pratt & Whitney. One such inspection checks for airfoil bowing and lean. A blade will bow or lean towards the suction face of the airfoil as a result of creep during engine operation. Third stage turbine blades from the JT8D low pressure turbine have been observed with as much as two millimetres of deflection measured at mid-span. In a geometrically correct T3 blade, the tensile centrifugal load due to engine rotation …

Development Of A Geothermal Heat Pump Test Facility, Chris Collins

Theses

Current environmental concerns have led to large scale research and development in the area of alternative energy supplies. The alternative energy system of interest in this study is the heat pump. Heat pumps extract heat from a variety of sources such as air, water and the earth, upgrade and transmit it to the required location. The aim of this thesis is to develop mathematical and experimental models to evaluate the performance of a heat pump which uses the earth as its thermal source. These models will then form the basis of design aids for installers sizing closed loop collection systems …