Engineering Commons^™

Investigating The Effects Of Network Dynamics On Quality Of Delivery Prediction And Monitoring For Video Delivery Networks, Obinna C. Izima

Doctoral

Video streaming over the Internet requires an optimized delivery system given the advances in network architecture, for example, Software Defined Networks. Machine Learning (ML) models have been deployed in an attempt to predict the quality of the video streams. Some of these efforts have considered the prediction of Quality of Delivery (QoD) metrics of the video stream in an effort to measure the quality of the video stream from the network perspective. In most cases, these models have either treated the ML algorithms as black-boxes or failed to capture the network dynamics of the associated video streams.

This PhD investigates …

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 …

Towards The Development Of A Balanced Legislative Framework For Consumer Data Protection In Electronic Commerce: The Case Of The Sultanate Of Oman, Talib Al Kharusi

Doctoral

This research aims to investigate whether the law as it currently stands in Oman provides adequate legal protection for personal data, to determine the current obstacles facing the electronic commerce sector, and to identify ways of overcoming such challenges. The empirical focus of this study will be electronic commerce transactions between companies and consumers. In this regard, the research will explore the perceptions of the main stakeholders towards privacy regulation and what implications these have for the growth of electronic commerce in Oman. The privacy that this research aims to explore is a complex issue since it concerns human feelings …

Investigation Of Domestic Level Ev Chargers In The Distribution Network: An Assessment And Mitigation Solution, Arsalan Hussain Zaidi

Doctoral

This research focuses on the electrification of the transport sector. Such electrification could potentially pose challenges to the distribution system operator (DSO) in terms of reliability, power quality and cost-effective implementation. This thesis contributes to both, an Electrical Vehicle (EV) load demand profiling and advanced use of reactive power compensation (D-STATCOM) to facilitate flexible and secure network operation. The main aim of this research is to investigate the planning and operation of low voltage distribution networks (LVDN) with increasing electrical vehicles (EVs) proliferation and the effects of higher demand charging systems. This work is based on two different independent strands …

Long-Term Durability Of Rooftop Grid-Connected Solar Photovoltaic Systems, Chibuisi Chinasaokwu Okorieimoh

Doctoral

Compared to their initial performance, solar photovoltaic (PV) arrays show long-term performance degradation, resulting in lower like-for-like efficiencies and performance ratios. The long-term durability of polycrystalline silicon (p-Si) solar PV modules in three roof-top grid-connected arrays has been examined. Electrical output, ambient temperature, cell temperature, solar irradiance, solar irradiation, and wind speed data were collected at hourly intervals from 2017 to 2021 from three 50 kWp PV installations in Northern Ireland. The results show the extent to which higher PV temperatures associated with more intense solar radiation decrease efficiency, fill factor and maximum power output for PV arrays in a …

Time-Resolved Method For Spectral Analysis Based On Linear Predictive Coding, With Application To Eeg Analysis, Jin Xu

Doctoral

EEG (Electroencephalogram) signal is a biological signal in BCI (Brain-Computer Interface) systems to realise the information exchange between the brain and the external environment. It is characterised by a poor signal-to-noise ratio, is time-varying, is intermittent and contains multiple frequency components. This research work has developed a new parameterised time-frequency method called the Linear Predictive Coding Pole Processing (LPCPP) method which can be used for identifying and tracking the dominant frequency components of an EEG signal. The LPCPP method further processes LPC (Linear Predictive Coding) poles to produce a series of reduced-order filter transfer functions to estimate the dominant frequencies. …

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 …

Inter-Microgrid Operation: Power Sharing, Frequency Restoration, Seamless Reconnection And Stability Analysis, Sandipan Patra

Doctoral

Electrification in the rural areas sometimes become very challenging due to area accessibility and economic concern. Standalone Microgrids (MGs) play a very crucial role in these kinds of a rural area where a large power grid is not available. The intermittent nature of distributed energy sources and the load uncertainties can create a power mismatch and can lead to frequency and voltage drop in rural isolated community MG. In order to avoid this, various intelligent load shedding techniques, installation of micro storage systems and coupling of neighbouring MGs can be adopted. Among these, the coupling of neighbouring MGs is the …

Optical Fiber Sensors For In-Situ Detection Of Solid-Liquid Phase Change For N-Octadecane, Wei Han

Doctoral

In the past few decades solid-liquid phase change materials (PCMs) have gained an increasingly important role in thermal energy storage applications due to their ability to absorb or release large amounts of energy during melting or solidification. The precise phase change temperature varies with different conditions, such as external pressure, small variations in the PCM composition in the case of multi-component mixtures and/or material purity. In order to achieve better energy efficiency for the energy storage process, it is necessary to be able to accurately detect the solid-liquid phase changes in the bulk of a PCM.

Optical fiber sensors allow …

Mode Analysis And Applications Of Three-Layer Step-Index And Depressed-Core Optical Fibers, Xiaokang Lian

Doctoral

Optical fibersplay important roles in telecommunication, imaging, sensing, lasers and amplifiers. The rapid development of fiberopticsover the past decades has beenunderpinnedbyvarious designs of the optical fibers and bythe rapid improvement of the understanding of the waveguiding mechanismsand associated models. According to the cross-section refractive index distribution, optical fibers can be generally classified into four basic types: two-layer step-index fiber, three-layer step-index fiber, three-layer depressed-core fiber and hollow-core fiber.Among these four basic fibertypes,the modeproperties and the applications of the three-layer step-index and depressed-core fibers have notbeensufficiently investigated. This thesis presents a detailedmode analysis in three-layer step-index and depressed-core fibers and their …

Phase Resolved Partial Discharge Evaluation At Dc Voltage, Tobias Dezenzo

Doctoral

Partial discharge diagnostics are common for the condition assessment of high voltage alternating current (ac) and direct current (dc) equipment. For ac applications the phase resolved partial discharge evaluation method has prevailed [1]. Even though, numerous methods for dc partial discharge diagnostics have been proposed no agreed standard exists. This is primarily because of the fact that these methods are not as easily applicable as the well-known, intuitive, pattern based phase resolved method. Due to the often assumed unavailability of a useable phase angle information [2]–[4] this method has never been transferred to dc partial discharge diagnostics. However, as a …

Investigation Into Photovoltaic Distributed Generation Penetration In The Low Voltage Distribution Network, Shivananda Pukhrem

Doctoral

Significant integration of photovoltaic distributed generation (PVDG) in the low voltage distribution network (LVDN) could potentially pose threats and challenges to the core activity of distribution system operators (DSO), which is to transport electrical energy in a reliable and cost-effective way. The main aim of this research is to investigate the active planning and operation of LVDNs with increased PVDG integration through steady state power system analysis. To address the impacts of voltage profile fluctuation due to power flow modification, this research proposes a probabilistic risk assessment of power quality (PQ) variations and events that may arise due to significant …

Dynamic Power System Training Simulation Platform And Tools For The Operational Management Of Smart Grids In The Liberalized Energy Market, Darlus France Mengapche

Doctoral

The major changes in distribution networks (medium and low voltage networks) over recent decades led to new challenges and issues in the operational management of these networks. Amongst others, issues such as load flow problems (power flow reversal, overloading of network equipment, network congestions), voltage problems (voltage limit violations, voltage increases and decreases, harmonics), power schedule management problems, network state estimation and problems with the operation of protection equipment could be encounterd. Besides, the control center staff which is confronted with new complex tasks, challenges and responsibilities, must be prepared and trained for the operational management of the future distribution …

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. …

High Sensitivity Optical Fiber Interferometric Sensors, Dejun Liu

Doctoral

Optical fiber interferometers have been widely employed and investigated for monitoring the changes in both physical and chemical parameters, with the advantages of compact size, light weight, immunity to electromagnetic interference, high sensitivity, capability to work in harsh environments and remote operation capabilities. Among the different kinds of fiber sensors based on interferometry, singlemode-multimode-singlemode (SMS) structures has attracted considerable interest due to their inherent advantages of high sensitivity, ease of fabrication and interconnection to other fiber systems and low cost. However, the challenge is that the sensitivity of the traditional SMS based fiber structure is not sufficient in some cases, …

Whispering-Gallery Mode Microsphere Resonators For Applications In Environmental Sensing, Arun Mallik

Doctoral

Humidity, temperature and volatile organic compounds (VOCs), particularly ammonia, are key environmental conditions that have a major impact on human comfort, well-being and productivity, as well as on agriculture, food processing and storage, electronic manufacturing and many other industries. This results in the urgent need for the development of sensing technologies allowing rapid detection and accurate measurement of these environmental parameters. Over the past decades many electrical as well as optical sensors have been proposed and demonstrated for environmental applications. However, challenge always exists for these sensors in terms of sensitivity, selectivity, detection limit, speed of response and robustness, where …

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 …

Spatial Thinking In The Engineering Curriculum: An Investigation Of The Relationship Between Problem Solving And Spatial Skills Among Engineering Students., Gavin Duffy

Doctoral

Long considered a primary factor of intelligence, spatial ability has been shown to correlate strongly with success in engineering education, yet is rarely included as a learning outcome in engineering programmes. A clearer understanding of how and why spatial ability impacts on performance in science, technology, engineering and mathematics (STEM) subjects would allow educators to determine if spatial skills development merits greater priority in STEM curricula. The aim of this study is to help inform that debate by shedding new light on the role of spatial thinking in STEM learning and allow teaching practice and curriculum design to be informed …

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 …

Hvdc Systems Fault Analysis Using Various Signal Processing Techniques, Benish Paily

Doctoral

The detection and fast clearance of faults are important for the safe and optimal operation of HVDC systems. In HVDC systems, various types of AC faults (rectifier & inverter side) and DC faults can occur. It is therefore necessary to detect the faults and classify them for better protection and diagnostics purposes. Various techniques for fault detection and classification in HVDC systems using signal processing techniques are presented and investigated in this research work. In this research work, it is shown that the wavelet transformation can effectively detect abrupt changes in system signals which are indicative of a fault. This …

Tapered Optical Microfibre Based Structures For Sensing Applications, Lin Bo

Doctoral

There has been an increasing demand in recent years from a wide variety of industries for sensors which combine high sensitivity, fast response, compact size and low power consumption. Tapered optical microfibres can generate easily accessible evanescent fields with a large intensity and short decay distance which make microfibres very suitable candidates as the basis of sensors to suit a variety of application areas. In this thesis, experimental research is presented concerning the development of sensors using structures based on tapered optical microfibres, with a particular emphasis on biochemical sensing applications. Light propagation along an optical microfibre depends on its …

Offshore Electrical Networks And Grid Integration Of Wave Energy Converter Arrays - Techno-Economic Optimisation Of Array Electrical Networks, Power Quality Assessment, And Irish Market Perspectives, Fergus Sharkey

Doctoral

Wave energy is an emerging industry and faces many challenges before commercial wave energy converter (WEC) arrays are installed. One of these challenges is the grid integration of WEC arrays. This includes offshore electrical networks, grid compliance, and access to electrical markets. This must be achieved in a technically viable manner and also at an acceptable cost. As electrical networks are expected to make up a large proportion of the overall WEC array CAPEX, perhaps up to 25%, this area is critical to the long term competitiveness of wave energy.

The objectives of this thesis are to develop technically and …

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 …

On A New Method For Interior Lighting Design, James Duff

Doctoral

In 2009, Christopher Cuttle began to challenge the suitability of the metrics contained within current lighting design standards and guidance. In short, Cuttle proposed a move away from providing an amount of light that relates to the difficulty of a visual task and instead, providing an amount of light that relates to the brightness of a space. This sense of brightness would be estimated by a new lighting metric, Mean Room Surface Exitance. The research presented in this thesis strove to examine, critically evaluate, analyse and investigate the merit of changing indoor lighting standards to include Mean Room Surface Exitance. …

Study Of Uhf And Vhf Compact Antennas, Abraham Loutridis

Doctoral

This thesis presents and describes designs of small antennas that operate in UHF and VHF frequency bands. The proposed antennas are designed for integration into small volumes, therefore low profile, compact size and good radiation properties are the key parameters in this work. A further investigation on miniaturization techniques, as well as the ground plane effects on the general performance, is also made. The main objective is the design of novel compact sized geometries, lightweight and cost efficient, operating in the lower UHF and VHF frequency bands. The groundplane size and the antenna position with respect to it, are two …

A Study Of The Impact Of Various Geometric Factors On The Capacity Of Short Range Indoor Mimo Communications Channels, Anthony Grennan

Doctoral

MIMO antenna array systems have been proposed as a means of increasing the spectral efficiency of wireless systems. However, their performance is likely to be sub-optimal if typical uniform antenna array structures are arbitrarily positioned; as they depend on spatial multiplexing. This is particularly true for indoor environments in which transmission ranges are short resulting in a strong correlation of the main propagation paths, especially the line-of-sight components. This makes it difficult to achieve successful spatial multiplexing which depends on a decorrelated set of signal components. Thus, the physical propagation channel and geometry of the antenna arrays, especially the inter-element …

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 …

Multimodal Wearable Sensors For Human-Machine Interfaces, Mark Nolan

Doctoral

Certain areas of the body, such as the hands, eyes and organs of speech production, provide high-bandwidth information channels from the conscious mind to the outside world. The objective of this research was to develop an innovative wearable sensor device that records signals from these areas more conveniently than has previously been possible, so that they can be harnessed for communication. A novel bioelectrical and biomechanical sensing device, the wearable endogenous biosignal sensor (WEBS), was developed and tested in various communication and clinical measurement applications.

One ground-breaking feature of the WEBS system is that it digitises biopotentials almost …