Engineering Commons^™

Development Of Holographic Recording Material For Fabrication Of Solar Concentrators For Micro Satellites, Brian Rogers

Doctoral

Holographic solar concentration has been a topic of increasing interest over recent years because of the lightweight and physically compact nature of holograms, which gives them an advantage over other, conventional concentration methods. As holographic recording materials develop further, their characteristics prove to meet the demands required of them to make more effective holographic solar concentrators. The development of photovoltaics in tandem with holographic materials has led to a host of solar concentrating device designs that take advantage of the unique properties of diffractive optics. Compared to refractive optics, holographic devices are more lightweight and compact. This makes holographic devices …

A Two-Level Information Modelling Translation Methodology And Framework To Achieve Semantic Interoperability In Constrained Geoobservational Sensor Systems, Paul Stacey

Doctoral

As geographical observational data capture, storage and sharing technologies such as in situ remote monitoring systems and spatial data infrastructures evolve, the vision of a Digital Earth, first articulated by Al Gore in 1998 is getting ever closer. However, there are still many challenges and open research questions. For example, data quality, provenance and heterogeneity remain an issue due to the complexity of geo-spatial data and information representation.

Observational data are often inadequately semantically enriched by geo-observational information systems or spatial data infrastructures and so they often do not fully capture the true meaning of the associated datasets. Furthermore, data …

The Study Of Reconfigurable Antennas And Associated Circuitry, Kansheng Yang [Thesis]

Doctoral

This research focuses on the design of pattern reconfigurable antennas and the associated circuitry. The proposed pattern reconfigurable antenna designs benefit from advantages such as maximum pattern diversity and optimum switching circuits to realise 5G reconfigurable antennas. Whereas MIMO based solutions can provide increased channel capacity, they demand high computational capability and power consumption due to multiple channel processing. This prevents their use in many applications most notably in the Internet of Things where power consumption is of key importance. A switched-beam diversity allows an energy-efficient solution improving the link budget even for small low-cost battery operated IoT/sensor network applications. …

On The Application Of Pspice For Localised Cloud Security, Paul Tobin

Doctoral

The work reported in this thesis commenced with a review of methods for creating random binary sequences for encoding data locally by the client before storing in the Cloud. The first method reviewed investigated evolutionary computing software which generated noise-producing functions from natural noise, a highly-speculative novel idea since noise is stochastic. Nevertheless, a function was created which generated noise to seed chaos oscillators which produced random binary sequences and this research led to a circuit-based one-time pad key chaos encoder for encrypting data. Circuit-based delay chaos oscillators, initialised with sampled electronic noise, were simulated in a linear circuit simulator …

A Two-Level Identity Model To Support Interoperability Of Identity Information In Electronic Health Record Systems., Xu Chen

Doctoral

The sharing and retrieval of health information for an electronic health record (EHR) across distributed systems involves a range of identified entities that are possible subjects of documentation (e.g., specimen, clinical analyser). Contemporary EHR specifications limit the types of entities that can be the subject of a record to health professionals and patients, thus limiting the use of two level models in healthcare information systems that contribute information to the EHR. The literature describes several information modelling approaches for EHRs, including so called “two level models”. These models differ in the amount of structure imposed on the information to be …

Enhanced Quality Of Experience Based On Enriched Network Centric And Access Control Mechanisms, Andreas Roos

Doctoral

In the digital world service provisioning in user satisfying quality has become the goal of any content or network provider. Besides having satisfied and therefore, loyal users, the creation of sustainable revenue streams is the most important issue for network operators [1], [2], [3]. The motivation of this work is to enhance the quality of experience of users when they connect to the Internet, request application services as well as to maintain full service when these users are on the move in WLAN based access networks. In this context, the aspect of additional revenue creation for network operators is considered …

A Remote Capacity Utilization Estimator For Wlans, Yi Ding

Doctoral

In WLANs, the capacity of a node is not fixed and can vary dramatically due to the shared nature of the medium under the IEEE 802.11 MAC mechanism. There are two main methods of capacity estimation in WLANs: Active methods based upon probing packets that consume the bandwidth of the channel and do not scale well. Passive methods based upon analyzing the transmitted packets that avoid the overhead of transmitting probe packets and perform with greater accuracy. Furthermore, passive methods can be implemented locally or remotely. Local passive methods require an additional dissemination mechanism in order to communicate the capacity …

Non-Negative Matrix Factorization Based Algorithms To Cluster Frequency Basis Functions For Monaural Sound Source Separation., Rajesh Jaiswal

Doctoral

Monophonic sound source separation (SSS) refers to a process that separates out audio signals produced from the individual sound sources in a given acoustic mixture, when the mixture signal is recorded using one microphone or is directly recorded onto one reproduction channel. Many audio applications such as pitch modification and automatic music transcription would benefit from the availability of segregated sound sources from the mixture of audio signals for further processing. Recently, Non-negative matrix factorization (NMF) has found application in monaural audio source separation due to its ability to factorize audio spectrograms into additive part-based basis functions, where the parts …

Grid Voltage Unbalance And The Integration Of Dfig’S, Joseph Kearney

Doctoral

Double-fed induction generators (DFIG’s) became the predominant generator installed for wind generation applications in the mid 1990’s. Issues pertaining to the operation and control of DFIG’s subsequently became apparent, particularly in weak areas of the grid network. Ironically weak areas of the grid tend to be where the average wind speed is high and the usual location of wind farms. One of the issues that emerged was the quality of the voltage in the network at the point of common coupling (PCC) with the DFIG’s. An important issue is the question of voltage unbalance at the PCC. As part of …

Advanced Circularly Polarised Microstrip Patch Antennas, Adam Z. Narbudowicz

Doctoral

The thesis describes outcomes of research on advanced circularly polarised antennas. The proposed designs are intended for integration into small mobile devices, therefore low profile and easy manufacturability are key parameters, along with good CP radiation properties. The designs were validated by simulation and measurement, and are also backed by theory and design guidelines. The primary focus is on the development of planar omnidirectional circularly polarised antennas, which are fabricated using multilayer PCB techniques and thus are lightweight and cost-efficient. Unlike in classical microstrip patch antenna designs, the groundplane of the proposed antenna was substantially reduced. This helps to achieve …

Development Of Novel Fiber Optic Humidity Sensors And Their Derived Applications, Jinesh Mathew

Doctoral

The main focus of this thesis is on the design and development of novel fiber optic devices for relative humidity (RH) sensing with emphasis on high sensitivity, a wide humidity range, low temperature dependence, fast response time and good stability.
Novel RH sensors based on fiber bends are fabricated by coating the surface of the buffer stripped bent fiber with selected hygroscopic materials such as Polyethylene oxide or Agarose. It is shown that the Polyethylene oxide coated device has a high sensitivity in a narrow RH range while the Agarose coated fiber bend shows a linear RH sensitivity in a …

Characterising Domestic Electricity Demand For Customer Load Profile Segmentation, Fintan Mcloughlin

Doctoral

The aim of this research was to characterise domestic electricity patterns of use on a diurnal, intra-daily and seasonal basis as a function of customer characteristics. This was done in order to produce a library of representative electricity demand load profiles that are characteristic of how households consume electricity. In so doing, a household’s electricity demand can be completely characterised based solely on their individual customer characteristics.

A number of different approaches were investigated as to their ability to characterise domestic electricity use. A statistical regression approach was evaluated which had the advantage of identifying key dwelling, occupant and appliance …

Power Quality Improvement Of Distributed Generation Integrated Network With Unified Power Quality Conditioner., Shafiuzzaman Khan Khadem

Doctoral

With the increased penetration of small scale renewable energy sources in the electrical distribution network, maintenance or improvement of power quality has become more critical than ever where the level of voltage and current harmonics or disturbances can vary widely. For this reason, Custom Power Devices (CPDs) such as the Unified Power Quality Conditioner (UPQC) can be the most appropriate solution for enhancing the dynamic performance of the distribution network, where accurate prior knowledge may not be available. Therefore, the main objective of the present research is to investigate the (i) placement (ii) integration (iii) capacity enhancement and (iv) real …

A Study Of Integrated Uwb Antennas Optimised For Time Domain Performance, Antoine Dumoulin

Doctoral

Antennas for impulse radio ultra-wideband based portable devices are required to be compact and able to transmit or receive waveforms with minimal distortion in order to support proximity ranging with a centimetre-scale precision. The first part of thesis characterises several pulse types for use in the generation of picosecond-scale signals in respect to the regulatory power and frequency standards while the principles of antenna transient transmission and reception are stated. The proximity effect of planar conductors on the performance of an ultra-wideband antenna is investigated in both spectral and temporal domain demonstrating the relationship between the antenna-reflector separation and the …

Monitoring And Regression Based Modelling Of End Winding Vibration In Large Synchronous Generators, David Shally

Doctoral

This research project was set up to monitor, on an ongoing basis, the condition of the end windings and their support structures of a 288 MVA 2-pole synchronous generator with a known end winding vibration problem
Excessive vibration at the end windings was caused by the natural frequencies of individual end bars (local) and of the entire end winding structure (global) being at or close to the magnetic forcing frequency of 100 Hz. Resonant vibration such as this has been a cause of major failures in machines of the same type in the past, resulting in significant down time ranging …

A Novel Qos-Aware Mpeg-4 Video Delivery Algorithm Over The Lossy Ieee 802.11 Wlans To Improve The Video Quality, Tanmoy Debnath

Doctoral

Video traffic is bursty in nature and has different network requirements compared to other types of traffic (e.g. voice, data) in terms of bandwidth, delay, jitter, and loss etc. So it becomes important to manage video traffic on a WLAN carefully to achieve acceptable levels of Quality of Service (QoS). The unique contribution of this work is that it presents experimental and simulation studies of the performance of real video content streamed over WLAN networks. Under various test scenarios the performance of the WLAN network in terms of delay, loss, throughput etc. is analysed in the presence of background traffic. …

Liquid Crystal Devices For Optical Communications And Sensing Applications, Sunish Mathews

Doctoral

This thesis is focussed on the design and development of liquid crystal based tunable photonic devices for applications in optical communications and optical sensing, with an emphasis on all-fiber device configuration. The infiltration of liquid crystals into photonic crystal fiber provides a suitable common platform to design and fabricate simple and compact all-fiber tunable photonic devices which can be easily integrated with optical fiber networks and sensing systems. Based on the infiltration of liquid crystals – materials with high dielectric anisotropy, into photonic crystal fibers a common platform is developed to address the need for electronically tunable photonic devices with …

Antennas For Portable Communications In The Uwb And Gps Spectra., Giuseppe Ruvio

Doctoral

The thesis describes a study of antennas for solutions in emerging systems. An account of the fundamental principles of these antennas is given together with an outline of the basic electromagnetic theory on which the designs are based. While the main focus is on antennas for Ultra Wideband (UWB) systems, some additional work was carried out on enhancing performance of circularly polarised antennas for satellite navigation systems. The study focussed on the design of highly efficient broadband antennas with particular requirements for size compactness, gain stability, phase-linearity, and the use of low-cost materials. These requirements are particularly important for UWB …

Drop Photometer Design., Kevin Tiernan

Doctoral

The tensiograph drop analyser, operating in the mode of ultraviolet-visual absorption photometer, was re-engineered to improve measurement accuracy. As well as instrumentation re-design, the other objective of the research was to analyse tensiograph signals to explore how their features are defined by drop properties. Using fibre optic technology, the tensiograph emits a light beam into a growing pendant drop whereupon it undergoes a number of internal reflections. A portion of the reflected light energy is coupled to a photodiode producing a proportional current that is electronically processed and transferred to a computer for analysis. The signal produced, known as the …