Masters

Monitoring and Regression Based Modelling of End Winding Vibration in Large Synchronous Generators.

David Shally — Wed, 13 Feb 2013 03:47:41 PST

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 from a few weeks to a number of months, with the obvious implications in terms of cost, generator availability and revenue loss. The project covers the installation of an end winding vibration monitoring system, subsequent analysis and testing in order to attempt to lower peak vibration levels, a low tune modification of the end winding support structure (carried out by the OEM) in order to remedy the natural frequency issue, subsequent data analysis and development of regression models to allow the prediction of vibration levels based on plant data and the implementation of the models on PI ACE (Advance Computing Engine). A webpage, available to all plant personnel via the company intranet was then created to display the actual measured vibration data against the model predicted values and other relevant plant data. With the issue of excessive vibration due to resonance having been remedied by the Original Equipment Manufacturer (OEM) the focus of the project shifted somewhat towards providing an easily interpreted, easily accessible method of monitoring the condition of a now relatively healthy machine well beyond the conclusion of this project. The development of the regression models and web page was seen as the best way of achieving this.

Probabilistic Analysis of Indeterminate Highway Bridges Considering Material Nonlinearity

Liam McCarthy — Wed, 12 Dec 2012 02:53:03 PST

With ever-reducing maintenance budgets and ever-deteriorating bridge infrastructure, th assessment of existing bridges is vital. Reliability analysis techniques are becomin increasingly popular in the structural safety assessment of existing bridge structures Commonly, a component based approach is used in reliability analysis techniques Traditional reliability procedures often employ a conservative definition of failure, in that th component is deemed to have failed when the strength capacity has been exceeded at a singl cross section. As a result, the component's degree of redundancy and ductility is ignored giving an often conservative estimate of the load carrying capacity of the bridge component Therefore, this dissertation is focused on the development of a reliability analysis procedur which accounts for material behaviour for indeterminate beams. The structural safety of a representative group of steel composite bridge beams is examined The material response of each beam subjected to a combination of both dead load and liv load is assessed using a one-dimensional nonlinear finite element analysis (NFEA) model The Response Surface Method (RSM) is then used to replace the NFEA model with a approximated explicitly-known polynomial function. This allows a First Order Reliabilit Method (FORM) analysis to be performed. The developed procedure is compared to th traditional approach with regard to three limit states. These limit states are defined as elasti member failure, first formation of a plastic hinge and ultimate failure. Ultimate failure occur when a collapse mechanism has formed. The live load on each structure consists of annua maximum traffic loading events determined from Monte Carlo Simulation (MCS) of Weigh in Motion (WIM) data. The modelling of realistic live loads highlights the practicality of th procedure developed. This procedure may act as a foundation for the development of a evaluation method accounting for material nonlinearity for existing bridge structures.

The Unprecedented Assimilation of Mobile Telephony in Ireland- a Phenomenon of the Celtic Tiger Era or a Result of Cultural Traits?

Andreas Scheibelhut — Wed, 14 Nov 2012 02:55:46 PST

Following the universal acceptance of mobile telephony the once elitist gadget has become an indispensable democratic tool of everyday communications over the last three decades. Controversially, this thesis illustrates that its level of both adoption and usage did not develop in a similar homogenous pattern in selected OECD countries. In particular, the Irish performance is rather astonishing given the speed of adoption as well as the exceptional high revenue figures achieved by the wireless operators. Consequently, this work determines a selection of factors that drive and encourage both the adoption and usage of cellular telephony in Ireland. The Irish experience is examined in the light of Rogers‘ theory of adoption and diffusion of innovation and demonstrates that domestic socio-economic factors such as the traditional Irish family structure helped the adoption process as did its young demography following the launch of prepaid services. Similarly, historic events such as emigration and the policy of attracting overseas companies to settle in Ireland created traits of a cosmopolite and open economy society whereas the civil war and governmental policies hindered the adequate rollout of the PSTN which resulted in a migration towards cellular telephony. Significantly, by deploying a linear regression model this thesis showed that Hofstede‘s cultural dimension of uncertainty avoidance correlates the most with mobile telephony adoption. Controversially, while this dimension is generally link with protestant cultures this finding is rather contradictive when recalling Ireland‘s tradition of Catholicism and puts a long-cherished stereotype associated with Ireland into question. It was further demonstrated that the Irish benefited from their selection of the global TACS standard that promised economies of scale and subsequently reasonable-priced equipment. Due to this selection the incumbent establish some form of international roaming, which was a novelty outside the NMT system sphere at the time. With regard to the exceptional revenue figures which were seen as a result of a ‗rip-off‘ policy by the wireless carriers this thesis found proof that they were in fact a consequence of the Irish‘s enthusiastic mobile phone usage rather than a product of over-charging. It was further demonstrated that the stereotype of the talkative Irish is profound in their legacy of story-telling as well as a consequence of the British suppression when the mother tongue was used to both conserve and keep their culture alive. Following the independence from their occupiers this regained freedom can easily be observed by the extensive rate of speech and ‗pirate‘ radio broadcastings. Altogether, it was shown that the Irish society resonate most fortune with the adoption of an innovation such as mobile telephony. Therewith, underpinning the relevance of cultural and social factors in addition to traditional solely economic and marked-orientated models.

Automatic Musical Instrument Identification

Joseph McKay (Thesis) — Mon, 10 Sep 2012 05:55:27 PDT

The increased availability of digital repositories of music coupled with the increase in demands of Music Information Retrieval (MIR) has spawned a growth in content-based multimedia retrieval systems. On a commercial level consumers demand more intelligent systems to satisfy their digital music requirements. Areas of MIR, which includes musical transcription, similarity, segmentation and classification would benefit significantly from efficient musical instrument classification technology. Many instrument classification systems have attempted to meet this challenge, yet most state-of-the-art systems are restricted to the monotimbral classification task. When faced with the real-world scenario of classifying polytimbral stereo musical mixtures, these systems lack the capability of performing the sophisticated processing required. Research has identified as desirable the reduction of the polytimbral classification task to that of classification of individual instrument sources which have been separated prior to the instrument classification process by way of sound source separation (SSS) algorithms. Such a system would prove powerful in MIR. The principal aim of this research is to establish a ground truth of the capabilities of the SSS algorithm ADRess as a preprocess to instrument identification in polytimbral musical signals. A thorough review of the instrument identification literature is provided which identifies the need for the capabilities of ADRess. Most popular digital music is in stereo format. Ground truth experiments using basic acoustic features with two common classifiers, k-Nearest Neighbour and Gaussian Mixture Model, succeed in identifying the ADRess separated sources from a synthetic polytimbral mixture of five non-percussive instruments. This novel contribution to the field of musical instrument identification opens the door to new possibilities/alternatives in the classification of stereo polytimbral signals. Polytimbral classification has been reduced to a simpler task. Current state-of-the-art systems can use ADRess as a preprocessing step and continue with their current timbre modelling approaches. However, ADRess does have its limitations. It is subject to artifacts distorting classification findings as a result of resynthesis of sources with overlapping harmonic partials. It is also at the mercy of the sound engineers who choose to position instruments across the stereo spectrum. However, instrument identification is no longer subject to the restrictions of current polytimbral approaches and ADRess oers a better alternative to SSS as a preprocessing step than current algorithms such as Independent Component Analysis and DUET.

Chemical-free Iron Removal and Disinfection Unit of Drinking Water for Single House Application

Michael O'Hehir (Thesis) — Wed, 02 Nov 2011 07:36:09 PDT

The supply of safe drinking water is a major worldwide problem. In the developed world the frequency of water related problems are increasing The shortage of fresh water supply is as a result of pollution from industrial, agricultural and natural disasters. To make water suitable for human consumption, it must first be treated. However, consumers do not always receive potable water even after public treatment. In some cases the consumer must treat the water being supplied to them, or have to source their own water from private wells and treat it prior to use. The purpose of this research was to develop a water treatment unit, that may be used for re-treating "mains" supplied water or water abstracted from private wells. In the case of re-treating water, the unit reedisinfects the water. This ensures that all pathogenic bacteria has been neutralised. In the case of treating well water, the main focus of this work is the removal of dissolved iron, followed by disinfection. The main application for this unit is mainly for single house operation under following parameters, That the treatment is carried out without the use of chemicals It is simple to maintain It can be constructed from readily available components It is inexpensive to build and operate It is small and compact Prior to designing and building the prototype test unit samples of ferruginous and bacteriologically contaminated water were first sourced. These samples were aerated to oxidise the dissolved iron out of solution to form solid particles, which could then be filtered out. Testing of various types of granular filter media was then carried out to ascertain their suitability, these tests were carried out in different filter body configurations in order to quantify flow rates of the water. This information was then used as a tool to aid the design of suitable filter units. Typically these samples were used directly from the source, in the case of ferruginous contamination. Samples of The bacteriologically contaminated water were taken from the source, some were processed through the treatment system, while the remainder were left untreated. The samples were delivered to the testing laboratories, as "before and afier treatment" within the specified time limit, generally delivered within 3-4 hours. Activated carbon filters were also used to remove the taste and odour associated with ferruginous water. The final stage of the treatment was disinfection, carried out by the use of ultraviolet radiation. Based on results obtained for various treatments undertaken, the water treatment unit developed for this research has proven to be a satisfactory method of producing potable water for domestic drinking and use. While the design of this unit concentrates on single dwelling application, it is possible that the unit could be expanded to treat small groups of dwellings.

Blind Single Channel Sound Source Separation

Mark Leddy (Thesis) — Wed, 02 Nov 2011 06:57:34 PDT

In recent years source separation has become an increasingly popular area of research in the signal processing community. The subject has found applications in a variety of fields such as medical imaging, sound and audio, econometrics and geophysics. This document will discuss the application of source separation techniques to the area of audio. Sound source separation is the process of observing a mixture signal made up of a number of sources, and from this mixture estimating the individual source signals. Audio source separation techniques may be crudely split into the following areas; techniques that utilise attributes of the sources, and that mimic methods used by the human auditory system to perform separation; and statistical, mathematical methods which do not necessarily take advantage of the attributes of sources. A further division is also possible whereby techniques utilise prior knowledge of sources, and those that do not, known as blind separation techniques. The novel work presented in this document discusses an approach for performing blind separation on a single channel mixture. The technique utilises attributes of the environment in which the the signal was recorded, and combined with the ADRess source separation algorithm, a novel process for source separation is presented.

Wood Chip Heating for Commercial Buildings in Ireland: An Analysis of Supply Methods and Financial Viability

Ciaran Berkeley (Thesis) — Wed, 02 Nov 2011 04:48:38 PDT

Ireland has three central issues regarding the supply and use of fuel and energy: import dependency; competitiveness; and greenhouse gases emissions. Ireland is ranked as one of the most import dependent states in the EU, with over 90% of its fuel sourced fiom abroad [IAEA, 20051. Combined with rapidly fluctuating oil and gas wsts and uncertainty with future supply, it is essential that Ireland find a more secure and sustainable alternative to fossil hels. Wood chip represents one such alternative energy source since it is locally produced and considered to be carbon-neutral. The main objective of this research is to assess the financial and environmental feasibility of wood chip as a heat source in Irish commercial buildings. The commercial range of boilers, finm 50kW up to 400kW, offers a good range of potential feasible and non-feasible arrangements that will provide important information regarding correct sizing and use. Secondary objectives include optimising production supply chains and heating system wnfigurations as well as commenting on relevant national policies. The swpe of the research covers all aspects of wood chip production and use for wmmercial applications in Ireland. Key methodologies employed include cost versus value techniques to examine supply chain efficiencies; mathematical modelling of energy balances; and net present value models to analyse the financial viability of wood chip heating systems. Results indicate that wood chip is an economically feasible replacement for oil and gas as a heat source in commercial buildings. Drying wood fuel both increases value and minimises supply costs. This increases the net present values of wood chip heating systems as they rewup their high initial capital wsts with the increased savings finm a cheaper fuel. Energy balance models show that installing wood chip boilers at part load offers more savings than boilers at full load, and that economic viability is highly sensitive to changes in fuel prices. Findings suggest that the regulation of wood fuel quality and the introduction carbon taxes will increase wood fuel uptake in the commercial sector.

Development of a Quality of Service Framework for Multimedia Streaming Applications

Stuart Wallace (Thesis) — Tue, 30 Aug 2011 08:09:09 PDT

By the year 2012, it is expected that the majority of all Internet traffic will be video content. Coupled with this is the increasing availability of Wireless Local Area Networks (WLANs) due to their ease of deployment, flexibility and reducing roll out costs. Unfortunately the contention based access mechanism utilised by IEEE 802.11 WLANs does not suit the non-uniform or bursty bandwidth profile of a video stream which can lead to a reduced quality of service (QoS) being experienced by the end-user. In 2005, the IEEE 802.11e protocol was ratified in an attempt to solve this emerging problem. It provides for an access prioritization mechanism based upon four separate traffic classes or access categories (ACs). Each AC is characterised by a set of access parameters that determine its level of access priority which is turn determines the amount of bandwidth available to it. Computer simulation studies have shown that AC prioritisation can yield significant improvements in the QoS delivered over a WLAN. However, these studies have been based upon the use of static access parameters for the ACs. In practice, this is not a viable solution owing to the dynamic and unpredictable nature of the operating conditions on WLANs. In this thesis, an experimental study of AC prioritisation based upon adaptive tuning of the access parameters is presented. This new approach to bandwidth provisioning for video streaming is shown to yield significant improvements in the QoS under a wide range of different operating conditions. For example, it is shown that by adaptively tuning the access control parameters in response to the network conditions, the number of video frames delivered that satisfy QoS requirements is more than doubled.

MeshScan: a Fast and Efficient Handoff Scheme for IEEE 802.11 Wireless Mesh Networks

Yin Chen (Thesis) — Wed, 23 Feb 2011 09:00:35 PST

As a next generation network solution, Wireless Mesh Networks (WMN) provides fast Internet access to a large area, which is from university campus to city scale. In order to provide an uninterrupted Internet experience to a mobile client, a process called handoff is required to maintain the network connection from one Mesh Node (MN) to another MN. Ideally, handoff should be completely transparent to mobile users. A critical application like VoIP will require a handoff capability that transfers a call from one mesh node (MN) to another in less than 50 msec. However the current IEEE 802.11 standards do not address the handoff well. Studies have revealed that standard handoff on IEEE 802.11 WLANs incurs a latency of the order of hundreds of milliseconds to several seconds. Moreover, the discovery step in the handoff process accounts for more than 99% of this latency. The study addresses the latency in the discovery step by introducing an efficient and powerful client-side scan technique called MeshScan which replaces the discovery step with a unicast scan that transmits Authentication Request frames to potential MNs. A prototype of MeshScan has been developed based on the MadWifi WLAN driver on Linux operating systems. The feasibility of MeshScan to support fast handoff in WMNs has been demonstrated through extensive computer simulations and experiments under same given conditions. The results from the simulations and experiments show that the latency associated with handoff can be reduced from seconds to a few milliseconds by using the MeshScan technique. Furthermore, it is shown that MeshScan can continue to function effectively even under heavy traffic loads.

An Experimental Analysis of the Call Capacity of IEEE 802.11b Wireless Local Area Networks for VoIP Telephony

Brian Keegan (Thesis) — Fri, 14 Jan 2011 07:27:22 PST

The use of the Internet to make phone calls is growing in popularity as the Voice over Internet protocol (VoIP) allows users to make phone calls virtually free of charge. The increased uptake of broadband services by domestic users will further increase the use of VoIP telephony. Furthermore, the emergence of low cost wireless networks (namely IEEE 802.11a/b/g WLANs) is expected to bring wireless VoIP into the mainstream. As the number of wireless hotspots increases more users will want to use VoIP calls wherever possible by connecting to open access points (AP). A major concern with VoIP is Quality of Service (QoS). In order for VoIP to be truly successful users must enjoy a similar perceived QoS as a call made over a traditional telephone network. There are many factors that influence QoS which include: throughput, packet delay, delay variation (or jitter), and packet loss. This thesis is an experimental study of the call capacity of an IEEE 802.11b network when using VoIP telephony. Experiments included increasing the number of VoIP stations and also increasing the level of background traffic until network saturation occurs. Results show that the network is capable of supporting at least 16 VoIP stations. Due to the operation of the IEEE 802.11 medium access control (MAC) mechanism, the AP acts as a bottleneck for all traffic destined for wireless stations, in that significant delays can be incurred by VoIP packets which can lead to a poor perceived QoS by users. Consequently the performance of the AP downlink is the critical component in determining VoIP call capacity.

Feasibility of Using Passive Monitoring Techniques in Mesh Networks for the Support of Routing

Chenzhe Zhang (Thesis) — Tue, 02 Nov 2010 07:52:53 PDT

In recent years, Wireless Mesh Networks (WMNs) have emerged as a promising solution to provide low cost access networks that extend Internet access and other networking services. Mesh routers form the backbone connectivity through cooperative routing in an often unstable wireless medium. Therefore, the techniques used to monitor and manage the performance of the wireless network are expected to play a significant role in providing the necessary performance metrics to help optimize the link performance in WMNs. This thesis initially presents an assessment of the correlation between passive monitoring and active probing techniques used for link performance measurement in single radio WMNs. The study reveals that by combining multiple performance metrics obtained by using passive monitoring, a high correlation with active probing can be achieved. The thesis then addresses the problem of the system performance degradation associated with simultaneous activation of multiple radios within a mesh node in a multi-radio environment. The experiments results suggest that the finite computing resource seems to be the limiting factor in the performance of a multi-radio mesh network. Having studied this characteristic of multi-radio networks, a similar approach as used in single radio mesh network analysis was taken to investigate the feasibility of passive monitoring in a multi-radio environment. The accuracy of the passive monitoring technique was compared with that of the active probing technique and the conclusion reached is that passive monitoring is a viable alternative to active probing technique in multi-radio mesh networks.

Production and Storage of Hydrogen

Michael Muller (Thesis) — Mon, 19 Jul 2010 08:24:41 PDT

The Faculty of Electrical Engineering and Information Technology at the University of Applied Science in Darmstadt runs several hydrogen-related experiments at their fuel cell laboratory. In cooperation with the Dublin Institute of Technology (DIT), a new project was started in 2007. The aim of this project was to develop an energy storage system, which would work with hydrogen as a high quality energy storage. This system was developed for using the electricity of solar panels in order to run an electrolyser. Hydrogen is produced and afterwards stored in an adequate storage tank. Once the hydrogen has been stored, it can be used by a fuel cell to produce electricity again, anytime energy is needed. The main difficulty of this project consists in storing the maximum amount of hydrogen with the minium loss of the energy needed for the periphery (cleaning, drying, storing).

Thermal testing of innovative building insulations

Eoghan Frawley (Thesis) — Wed, 18 Nov 2009 09:15:44 PST

The main objective of this research was to design and develop a Hot Box to test the thermal properties of Eco-quilt multi-foil insulation. This work began by gaining an understanding into how multi-foil works, how it is installed and examining different variations of this insulation. It was clear at an early stage that there were two conflicting opinions on the thermal performance of multi-foils. One set of tests claimed that the insulation had a thermal resistance of approximately 5 m2oC/W. These tests were carried out in real weather conditions, where temperatures were fluctuating, although one laboratory test achieved similar results. The second types of tests were based on standardised EN ISO test methods and the results were in general agreement that the thermal resistance of multi-foils was approximately 1.7 m2oC/W. The results of initial tests conducted on multi-foil with a basic testing facility were in general agreement with the results of the EN ISO test methods. It was noted that this initial testing facility had certain limitations and it was decided to build a more advanced test rig to conduct further tests on Eco-quilt. Research was conducted into three types of Hot Box testing apparatus and a new testing facility, based on a Guarded Hot Box, was designed and constructed. A comparative test method was employed to evaluate Eco-quilt. This involved comparing insulation, with known thermal properties, directly with Eco-quilt while keeping the test conditions, for each test, as similar as possible. The results were in good agreement with the tests that found the thermal resistance equal to 1.7 m2oC/W. Other tests conducted showed that the performance of multi-foil is reduced when manufacturers’ installation procedures are not followed. It was found that the testing facility produced repeatable and meaningful results and could be used in the future to offer a good indication of the thermal performance of new insulations being developed.

A mobile ECG monitoring system with context collection

Jin Peng Li (Thesis) — Mon, 26 Jan 2009 09:01:58 PST

An objective of a health process is one where patients can stay healthy with the support of expert medical advice when they need it, at any location and any time. An associated aim would be the development of a system which places increased emphasis on preventative measures as a first point of contact with the patient. This research is a step along the road towards this type of preventative healthcare for cardiac patients. It seeks to develop a smart mobile ECG monitoring system that requests and records context information about what is happening around the subject when an arrhythmia event occurs. Context information about the subject’s activities of daily living will, it is hoped, provide an enriched data set for clinicians and so improve clinical decision making. As a first step towards a mobile cardiac wellness guidelines system, the focus of this work is to develop a system that can receive bio-signals wirelessly, analyzing and storing the bio-signal in a handheld device and can collect context information when there are significant changes in bio-signs. For this purpose the author will use a low cost development environment to program a state of the art wireless prototype on a handheld computer that detects and responds to changes in the heart rate as calculated form the interval between successive heart beats. Although the general approach take in this work could be applied to a wide range of bio-signals, the research will focus on ECG signals. The pieces of the system are, A wireless receiver, data collection and storage module An efficient real time ECG beat detection algorithm A rule based (Event-Condition-Action) interactive system A simple user interface, which can request additional information form the user. A selection of real-time ECG detection algorithms have been investigated and one algorithm was implemented in MATLAB [110] and then in Java [142] for this project. In order to collect ECG signals (and in principle any signals) the generalised data collection architecture has also been developed utilizing Java [142] and Bluetooth [5] technology. This architecture uses an implementation of the abstract factory pattern [91] to ensure that the communication channel can be changed conveniently. Another core part of this project is a “wellness” guideline based on Event-Condition-Action (E-C-A) [68] production rule approach that originated in active databases. The work also focuses on design of a guideline based expert system which an E-C-A based implementation will be fully event driven using the Java programming language. Based on the author’s experience and the literature review, some important issues in mobile healthcare along with the corresponding reasons, consequences and possible solutions will be presented.

Noise abatement and night deliveries

Hugh Finlay (Thesis) — Fri, 16 Jan 2009 08:21:47 PST

ABSTRACT The hypothesis is tested that – Acoustic materials are available or can be developed and applied to Heavy Goods Vehicles and ancillaries, which effectively and economically abate the noise caused by night deliveries The MPhil is a part of a wider innovation research partnership that aimed to develop sustainable solutions for the growing trend to night deliveries in Dublin city centre. The methodology involves; a review of international best practice for urban traffic noise abatement: a social and commercial justification for developing low noise products and procedures: field trials of kerb-side deliveries to city centre shops to identify the “peak” noise events and their associated signature frequencies: an identification of the HGV components and ancillaries to which noise attenuation solutions might best be applied: the selection, matching and pre-screening of suitable acoustic coatings for application to HGV trailer bodies and tail lifts: the development and evaluation of a hush-kit for easy retro-fitting to steel roll-cages. Laboratory and field experiments and special test equipment were designed to support and to validate the research. The research concentrates on bringing forward two sets of solutions (a) the application of an acoustic coating to the HGV trailer unit and tail-lift platform and (b) the development of a hush-kit for the steel roll-cages. The focus is on attenuating the identifiable peak impact noises by matching these with a coating and materials that can dampen the characteristic high frequency sounds. Recommendations are made for further research to optimise the performance of the prototypes developed. ABSTRACT The hypothesis is tested that – Acoustic materials are available or can be developed and applied to Heavy Goods Vehicles and ancillaries, which effectively and economically abate the noise caused by night deliveries The MPhil is a part of a wider innovation research partnership that aimed to develop sustainable solutions for the growing trend to night deliveries in Dublin city centre. The methodology involves; a review of international best practice for urban traffic noise abatement: a social and commercial justification for developing low noise products and procedures: field trials of kerb-side deliveries to city centre shops to identify the “peak” noise events and their associated signature frequencies: an identification of the HGV components and ancillaries to which noise attenuation solutions might best be applied: the selection, matching and pre-screening of suitable acoustic coatings for application to HGV trailer bodies and tail lifts: the development and evaluation of a hush-kit for easy retro-fitting to steel roll-cages. Laboratory and field experiments and special test equipment were designed to support and to validate the research. The research concentrates on bringing forward two sets of solutions (a) the application of an acoustic coating to the HGV trailer unit and tail-lift platform and (b) the development of a hush-kit for the steel roll-cages. The focus is on attenuating the identifiable peak impact noises by matching these with a coating and materials that can dampen the characteristic high frequency sounds. Recommendations are made for further research to optimise the performance of the prototypes developed. ABSTRACT The hypothesis is tested that – Acoustic materials are available or can be developed and applied to Heavy Goods Vehicles and ancillaries, which effectively and economically abate the noise caused by night deliveries The MPhil is a part of a wider innovation research partnership that aimed to develop sustainable solutions for the growing trend to night deliveries in Dublin city centre. The methodology involves; a review of international best practice for urban traffic noise abatement: a social and commercial justification for developing low noise products and procedures: field trials of kerb-side deliveries to city centre shops to identify the “peak” noise events and their associated signature frequencies: an identification of the HGV components and ancillaries to which noise attenuation solutions might best be applied: the selection, matching and pre-screening of suitable acoustic coatings for application to HGV trailer bodies and tail lifts: the development and evaluation of a hush-kit for easy retro-fitting to steel roll-cages. Laboratory and field experiments and special test equipment were designed to support and to validate the research. The research concentrates on bringing forward two sets of solutions (a) the application of an acoustic coating to the HGV trailer unit and tail-lift platform and (b) the development of a hush-kit for the steel roll-cages. The focus is on attenuating the identifiable peak impact noises by matching these with a coating and materials that can dampen the characteristic high frequency sounds. Recommendations are made for further research to optimise the performance of the prototypes developed. ABSTRACT The hypothesis is tested that – Acoustic materials are available or can be developed and applied to Heavy Goods Vehicles and ancillaries, which effectively and economically abate the noise caused by night deliveries The MPhil is a part of a wider innovation research partnership that aimed to develop sustainable solutions for the growing trend to night deliveries in Dublin city centre. The methodology involves; a review of international best practice for urban traffic noise abatement: a social and commercial justification for developing low noise products and procedures: field trials of kerb-side deliveries to city centre shops to identify the “peak” noise events and their associated signature frequencies: an identification of the HGV components and ancillaries to which noise attenuation solutions might best be applied: the selection, matching and pre-screening of suitable acoustic coatings for application to HGV trailer bodies and tail lifts: the development and evaluation of a hush-kit for easy retro-fitting to steel roll-cages. Laboratory and field experiments and special test equipment were designed to support and to validate the research. The research concentrates on bringing forward two sets of solutions (a) the application of an acoustic coating to the HGV trailer unit and tail-lift platform and (b) the development of a hush-kit for the steel roll-cages. The focus is on attenuating the identifiable peak impact noises by matching these with a coating and materials that can dampen the characteristic high frequency sounds. Recommendations are made for further research to optimise the performance of the prototypes developed.

Investigation of dynamic and steady state calculation methodologies for determination of building energy performance in the context of the EPBD

Mervin Dean Doyle (Thesis) — Fri, 12 Dec 2008 04:13:01 PST

The aim of this thesis was to investigate the ability of a dynamic and a quasi-steady state calculation methodology to capture the heating and cooling aspects of a buildings energy performance in the context of the requirements of the EU Energy Performance of Buildings Directive (EPBD). Chapters 1 and 2 provide a general background review and description of the implementation of the directive’s requirements in Ireland. Chapter 3 established the usefulness and relevance of building energy benchmarks, traditional approaches to building energy performance calculation methodologies. Chapter 4 established the ability of a sample of simplified and dynamic calculation tools to deal with the requirements set out in the directive and the extent the requirements are dealt with. This investigation observed that the underlying calculations and assumptions vary across different calculation tools; resulting in a variety of energy performance solutions. Chapter 5 investigated the ability of a dynamic methodology (IES) and simplified quasi-steady state methodology (SBEM/ prEN 13790) to capture the effects of variation of key parameters of a building design in order to generate an improvement in energy performance. The investigation analysed the sensitivity of both methodologies to the variation of design parameters and their effect in terms of the annual energy performance calculation. In addition, the calculation algorithms of both IES and SBEM were summarised and analysed to account for the difference in results obtained. This investigation established that a dynamic methodology rewards design improvements with greater magnitude than a quasi-steady state methodology.

Numerical prediction of primary and secondary flows in a Ranque-Hilsch vortex tube

Ronan Oliver (Thesis) — Mon, 15 Sep 2008 07:10:55 PDT

The primary aim of this project is to obtain a fundamental understanding of the fluid dynamics and thermodynamics of the primary and secondary flows in a Ranque-Hilsch Vortex Tube (RHVT). These flows are highly complex and are three dimensional, compressible and viscous in nature. To obtain an understanding of these, a state of the art Computational Fluid Dynamics (CFD) software package is applied for flow prediction with advanced turbulence models, and is employed to predict the primary and secondary flows in a RHVT. The models that are used include : the k-e model, the SST model by Menter, and the Reynolds Stress Model. The results from the turbulence modes are analysed and compared to establish how accurate they are at computing this type of flow field. In this CFD study of the RHVT, the flow fields and temperature outputs are investigated. This study begins with the appropriate selection of experimental results from a range of authors for similar vortex tubes. These results are collated and a three dimensional model of a similar experimental RHVT is drawn, upon which an unstructured tetrahedral mesh is developed using the CAD and meshing facilities of the CFD package respectively. This model is developed in such a way that components of the RHVT could be easily adjusted in size in order to carry out small scale parametric studies of the vortex tube. The analysis moves on to the correct stipulation of suitable and accurate boundary conditions. Once a set of appropriate and realistic boundary conditions is established, the flow fields within the RHVT are captured. Initially the k –e turbulence model is utilised to perform a mesh element density convergence study with the cold static and total temperature outputs of the RHVT as the measured criteria. Once mesh independent results are established, additional turbulence models such as the SST model by Menter and the Reynolds Stress model are run on this mesh to ascertain the performance of each turbulence model. When the optimum turbulence model is ascertained and investigation was carried out into the source of heat migration in the RHVT. This began by varying the tube geometry, i.e. the cold outlet diameter, and analysing its influence on the presence of secondary flow and therefore the influence of secondary flow on the heat transfer within the RHVT. An additional analysis of the work due to friction within the vortex tube is also performed in order to verify the presence of such work within the RHVT. Finally a recommendation is made within the conclusion of this thesis as to a method of how to take the study of work due to friction within the vortex tube forward for further analysis.

Development of probalistic techniques for network assessment with significant wind generation

Asim Mumtaz (Thesis) — Wed, 10 Sep 2008 05:56:23 PDT

Due to increasing awareness of global warming and high energy costs, more electrical power is being generated by using renewable sources. However some of these sources are not as predictable as conventional generation and they also lack the ability to be dispatched in the same way. The increase in the amount of wind power connected to transmission networks has been significant in some countries. But due to the stochastic nature of wind power, it is difficult to predict exactly how much power can be generated at any given time. This variable nature of wind power can cause line overloading and high voltage problems. To overcome these problems transmission networks can be upgraded but the cost of upgrade can make it uneconomical to accommodate wind power. Although wind turbines have very high availability rates, their ability to generate wind power depends on the wind speed. Most wind farms have capacity factors in the range of 30%-40%. The probability of wind farms operating at their rated output is quite low. As most techniques used to analyse new connections to transmission grids are based on conventional generation, these techniques can not be used for wind generation as they do not consider the variable nature of wind power. Probabilistic techniques have been used particularly in deregulated power systems where more than one company is involved in transmission system operation. Ireland has very high potential for wind generation due to its geographical location. But its transmission network is weak in some of the areas suitable for wind generation and the network has a low level of interconnection with other networks. Having a high level of wind generation can create significant reliability problems. To accommodate more wind generation, different analysis techniques have to be used to consider the variable nature of wind speed. The purpose of this research is to study and develop these probabilistic techniques and to investigate how these techniques can be used in Ireland to identify possible line overloading problems due to wind generation. Different cases with wind generation where probabilistic methods can be used or have been used are studied. A small part of the Irish transmission network with a significant level of wind generation connected is chosen for probabilistic analysis. Deterministic approaches are generally used to investigate the performance of the network. In this study, it is shown how probabilistic techniques can be used to give a clear picture of wind generation effects on transmission line overloading. The Line Flow Sensitivity Factor (LFSF) method is used to speed up the probabilistic analysis. By using probabilistic techniques for different periods of the year, analysis based on line overloading and reverse power flow are carried out. The amount of Expected Energy Not Produced (EENP) is calculated for different periods of the year. Based on the EENP, it can be decided whether it is economical to upgrade the transmission network or to curtail wind power during high wind production periods.

Design and development of a respiratory monitoring device to be used in conjuction with MRI scanners

Aidan McNally (Thesis) — Wed, 27 Aug 2008 07:32:23 PDT

The aim of this project was to design and manufacture a respiratory monitoring device that operates in conjunction with MRI scanners to produce higher quality images. The resultant quality of many MRI images depends on how well the patient can control their breathing activity. This research has been successful in designing and manufacturing a device that can be used to teach patients how to hold their breath correctly prior to scanning and also provide them with feedback about their breathing activity during the scan The project involved research into MRI technology and the materials that can still be used in the MRI environment. This heavily influenced the design of the transducer for monitoring breathing and the design of the feedback systems for providing the patient with information about their breathing activity during the scan. The system for breath monitoring is a rubber bladder, which is strapped to the chest of the patient, and is connected to a pressure transducer. This bladder is a low design compared to similar transducers already on the market and tests have shown similar performances between all of them. A number of different feedback systems have been designed that can work together or separately as required. These include a visual method where information is transmitted from a bar graph LED display via polymer optical fibres to the patient. Software was also written to generate a graphical display of the breathing activity and to produce a corresponding audio tone. A requirement of the respiratory monitoring device was for it to be compact and ergonomically designed. Various manufacturing processes were investigated and researched in order to produce a suitable housing for the device. An initial rapid prototype model was made from which new ideas were obtained. It was finally decided to use a vacuum forming process to make the housing from ABS plastic. The European Union Medical Devices Directive was consulted and examined and its rules followed to ensure that the device is in compliance with medical standards. The necessary documentation for CE Making of the finished product has also been prepared. The entire device has been tested within the MRI environment with positive results.

The computerised design of prestressed concrete slabs

Ronan Hogan (Thesis) — Tue, 26 Aug 2008 06:27:42 PDT

This thesis was aimed at the development of a finite element based software package for the analysis and design of prestressed concrete slabs. Many of the existing packages used in this area carry out a simplified two dimensional analysis of the slab which does not account for the secondary stresses set up by the presence of openings and notches in the slab. In an attempt to overcome this particular weakness, a finite element analysis package was written to help produce a more rigorous analysis of the stresses developed in prestressed concrete. The aims of the research were the examination of prestressed concrete theory, the identification of a suitable finite element model and the implementation of both theory and model through a purpose written software package. A combination of two finite element models, plate bending and plane stress, were used to simulate the effect of the axial stress imparted to the concrete by the strands and the moment applied to the section due to the eccentricity of the strands. The stresses encountered at transfer and during service conditions were examined in the software. Good programming practices such as minimised storage structures and the development of an efficient matrix solver were integral to the development of an effective software tool. Finally, the results produced by the software were examined and compared with those calculated using an established finite element analysis package. Ansys was chosen for this purpose as it has the flexibility to be applied to this particular package. The process of writing the software showed that an extensive amount of work was involved in debugging the code. An understanding was developed of the stages of evolution through which software of this type passes before completion. The software produced results that were broadly in line with those predicted by Anysys. However, the arduous task of setting up the model in Ansys showed that software tailored for use in the prestressed concrete field that would produce reasonably accurate results would have a place in industry.