Physical Sciences and Mathematics Commons^™

Localised Galvanic Corrosion Processes In Thermal Spray Coated/Cast Aluminium Alloy Systems, David Culliton, Tony Betts, David Kennedy

Conference Papers

Cast Aluminium Alloys, because of the propensity of aluminium to react with impurities and alloying elements, are prone to developing IM impurities during the solidification process. These IM phases can act, in some fluids, as initiation sites for localised corrosion processes, resulting in degradation phenomena, such as pitting. Whilst Thermal Spray coatings can improve the wear resistance of Cast Aluminium Alloys, their corrosion performance may be hampered by the presence of through porosity within the coating.

The present work details some preliminary studies of the localised corrosion processes occurring at the interface area between a Thermal Spray coating and a …

Structure Property Relationships In Organic Conjugated Systems, Luke O'Neill

Doctoral

A series of pi(п) conjugated oligomers containing 1 to 6 monomer units were studied by absorption and photoluminescence spectroscopies. The results are discussed and examined with regard to the variation of the optical properties with the increase of effective conjugation length. It was found that there was a linear relationship between the positioning of the absorption and photoluminescence maxima plotted against inverse conjugation length. The relationships are in good agreement with the simple particle in a box method, one of the earliest descriptions of the properties of one-dimensional organic molecules. Variations in the infinite chain limit band gap for a …

Hand-Held Flyback Driven Coaxial Dielectric Barrier Discharge: Development And Characterization, Victor J. Law, Vladimir Milosavljevic, Neil O’Connor, James F. Lalor, Steven Daniels

Articles

The development of a handheld single and triple chamber atmospheric pressure coaxial dielectric barrier discharge driven by Flyback circuitry for helium and argon discharges is described. The Flyback uses external metal-oxide-semiconductor field-effect transistor power switching technology and the transformer operates in the continuous current mode to convert a continuous dc power of 10–33 W to generate a 1.2–1.6 kV 3.5 μs pulse. An argon discharge breakdown voltage of ∼768 V is measured. With a 50 kHz, pulse repetition rate and an argon flow rate of 0.5–10 argon slm (slm denotes standard liters per minute), the electrical power density deposited in …

Development Of A Workflow For The Comparison Of Classification Techniques, Zanifa Omary

Masters

As the interest in machine learning and data mining springs up, the problem of how to assess learning algorithms and compare classifiers become more pressing. This has been associated with the lack of comprehensive and complete workflow depending on the project scale to provide guidance to its users. This means the success or failure of the project can be highly dependent on the person or team carrying it. The standard practice adopted by many researchers and experimenters has been to follow steps or phases from existing workflows such as CRISP-DM, KDD and SASSEMMA. However, as machine learning and data mining …

A Web-Based And Mobile Environmental Management System, James Carswell, Keith Gardiner, Michela Bertolotto, Andrea Rizzini, A Mandrak

Articles

This paper describes a Web-based and mobile system specifically developed to monitor fish species at risk. Such a system integrates spatial functionality to allow users not only to visualise maps and metadata of the area of concern but also to perform context-aware queries and updating of spatial datasets. The spatial datasets are provided by the Canadian Department of Fisheries and Oceans (DFO) and the prototype is customised to the specific needs of the Great Lakes Laboratory for Fisheries and Aquatic Sciences (GLLFAS) Fish Habitat Section requirements for fish species at risk assessment. Currently, researchers, habitat biologists and enforcement officers have …

Correlation Of Vibrational Intensity With Fluorescence Lifetimes In Π Conjugated Polymers, Luke O'Neill, Patrick Lynch, Mary Mcnamara, Hugh Byrne

Articles

A series of novel pi (p) conjugated polymers, originating from the archetypical Polyphenylene vinylene, in which the phenyl units are successively replaced by the larger naphthyl and anthryl acene units, were previously found to have a well-defined relationship between their relative fluorescence yields and their vibrational characteristics, as determined by Raman spectroscopy. In this study the Strickler–Berg equation is used to probe the influence of continual substitution of higher order acene units into the conjugated backbone in terms of the variation of the radiative and non-radiative rates. The deconvolution of the radiative and non-radiative rates enables the correlation of the …

An Integrated Approach To The Toxicity Evaluation Of Irish Marine Sediment - Chemical Assessment, Michelle Giltrap

Doctoral

This project was a collaborative project between the Marine Institute (MI) in Galway and Radiation and Environmental Science Centre (RESC) in the Technological University Dublin (DIT). In Ireland, at present, sediment quality assessments are generally reliant on chemical analysis alone with limited bioassay techniques available to further characterise the sediment. Some causative agents of toxicity to biological organisms are below analytical detection limits. Integration of bioassay data with chemical analysis is essential in order to complete a full ecotoxicological assessment of the quality of the marine environment. This project describes the chemical analysis of marine sediment for persistent pollutants from …

Langer's Method For The Calculation Of Escape Rates And Its Application To Systems Of Ferromagnets, Gerard Duff

Doctoral

This work is a study of the application of a theory proposed by J. S. Langer (J.S. Langer, Statistical Theory of the Decay of Metastable States, Annals of Physics 54, 258-275 (1969)) for the calculation of the decay rate (relaxation rate) of a metastable state. The theory is set in the context of statistical mechanics, where the dynamics of a system with a large number of degrees of freedom (order 1023) are reduced to N degrees of freedom, where N is small, when a steady state or equilibrium position is maintained by the entire system. In this thesis N equals …

Environmental Limits On The Nonresonant Cosmic-Ray Current-Driven Instability, Brian Reville, John Kirk, Peter Duffy, Stephen O'Sullivan

Articles

We investigate the so-called nonresonant cosmic-ray streaming instability, first discussed by Bell (2004). The extent to which thermal damping and ion-neutral collisions reduce the growth of this instability is calculated. Limits on the growth of the nonresonant mode in SN1006 and RX J1713.7-3946 are presented.

Some Rather Mechanical Reflections On Symmetry: In Art, Science, Engineering, Mathematics, Etc., Jim Mcgovern

Articles

This Inaugural Lecture consists of some of my rather mechanical, being an engineer, reflections on symmetry in diverse areas such as art, science, engineering, mathematics, etc. I explain what symmetry is to me, giving examples with lots of images and mentioning or at least barely referencing art, science, architecture, engineering, heritage, cosmology, bicycles, flight, invention, ingenuity, history, wallpaper, mathematics, typography, structures, regular shapes, coordinate systems, spacetime, thermodynamics and suchlike.

A Generic Approach And Framework For Managing Complex Information, Essam Mansour

Doctoral

Several application domains, such as healthcare, incorporate domain knowledge into their day-to-day activities to standardise and enhance their performance. Such incorporation produces complex information, which contains two main clusters (active and passive) of information that have internal connections between them. The active cluster determines the recommended procedure that should be taken as a reaction to specific situations. The passive cluster determines the information that describes these situations and other descriptive information plus the execution history of the complex information. In the healthcare domain, a medical patient plan is an example for complex information produced during the disease management activity from …

The Production Of High-Quality Video For E-Learning, Eugene Mcgovern, Audrey Martin, Roy Moore

Articles

As video capture, editing and transmission capabilities become more accessible, video is increasingly being considered when developing e-learning content. However, the skills required for video production are not commonly part of many e-learning developers backgrounds. This paper presents the experiences of academics from the spatial information sciences when developing high quality video content for an on-line e-learning module in Global Navigation Satellite Systems (GNSS). Video comprises one element of the module and is designed to, as far as possible, address the lack of ‘hands-on’ experience of GNSS equipment and observing procedures. The video element of the module was used by …

The Application Of Web 2.0 Technologies As An Experimental Method Of Teaching Remote Sensing At Dit, Ireland, Avril Behan

Conference Papers

This paper describes the implementation of an experimental method of delivery for a module of remote sensing material to second year students on the BSc (Hons) in Geomatics at the Dublin Institute of Technology. The project began as a reaction to poor levels of student engagement and unsatisfactory grades, as well as the requirement to focus more on real-world type problems due to the implementation of a work-placement semester for third year students. Both pedagogical considerations (movement towards formative feedback, interactivity and group-based work) and the effect of technological drivers, such as the popularity of the internet in general and …

An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance (Revised Version) 2008, Jim Mcgovern

Conference Papers

A particular discrete rhombohedral lattice consisting of four symmetrically interlaced cuboctahedral point lattices is described that is interesting because of the high degree of symmetry it exhibits. The four constituent cuboctahedral lattices are denoted by four colours and the composite lattice is referred to as a 4-colour rhombohedral lattice. Each point of the 4-colour lattice can be referenced by an integer 4-tuple containing only the positive non-zero integers (the counting numbers). The relationship between the discrete rhombohedral lattice and a discrete Cartesian lattice is explained. Some interesting aspects of the lattice and of the counting-number 4-tuple coordinate system are pointed …

Metrology And Proportion In The Ecclesiastical Architecture Of Medieval Ireland, Avril Behan, Rachel Moss

Conference Papers

The aim of this paper is to examine the extent to which detailed empirical analysis of the metrology and proportional systems used in the design of Irish ecclesiastical architecture can be analysed to provide historical information not otherwise available. Focussing on a relatively limited sample of window tracery designs as a case study, it will first set out to establish what, if any, systems were in use, and then what light these might shed on the background, training and work practices of the masons, and, by association, the patrons responsible for employing them.

An Exploration Of A Discrete Rhombohedral Lattice Of Possible Engineering Or Physical Relevance, Jim Mcgovern

Conference Papers

A particular discrete rhombohedral lattice consisting of four symmetrically interlaced cuboctahedral or cubic point lattices is described that is interesting because of the high degree of symmetry it exhibits. The four constituent lattices are denoted by four colours and the composite lattice is referred to as a 4-colour rhombohedral lattice. Each point of the 4-colour lattice can be referenced by an integer 4-tuple containing only the positive non-zero integers (the counting numbers). The relationship between the discrete rhombohedral lattice and a discrete Cartesian lattice is explained. Some interesting aspects of the lattice and of the counting-number 4-tuple coordinate system are …

Working Report On The Status Quo Of Nanomaterials Impact On Health And Environment, Harald Krug, Margarita Apostolova, Marite Arija Bake, Gordon Chambers, Horia Chiriac, Eva Herzog, Victoria Hand, Jürgen Höck, Peter Hoet, Nicoleta Lupu, Declan Mccormack, Maja Remskar, George Robillard, Jamila Smisterova, Jan Stetkiewicz, Speranta Tanasescu, Aris Tsatsakis, David Vaughn, Peter Wick, Jörg Wörle-Knirsch

Articles

Nanotechnology is regarded as one of the key technologies of the future and associated with high expectations by politics, science and economy. Artificially produced nanosized particles and nanoscale system components have new properties which are of importance for the development of new products and applications. Such new properties of materials and substances result from the special properties of surfaces and interfaces and in part, from the geometric shape of the material. In theory nanoparticles (NPs) can be produced from nearly any chemical; however, most NPs that are currently in use today have been made from transition metals, silicon, carbon (single-walled …

Photoactive Supramolecular Cyclodextrin Assemblies, Muath Atmeh

Doctoral

Ligands with a macrocyclic host unit attached to a photoactive metal core are of interest across a range of applications from luminescent or electrochemical sensors, light harvesting and energy-collection purposes. Their versatile properties and possibility of associating cyclodextrins with other molecules both covalently and non-covalently mean that these macrocyclic ligands can be employed in the design and the formation of supramolecular complexes. A particularly attractive proposition is to combine the selective inclusion capabilities of CD with luminophores which may act as reporters of binding or other interactions at the cyclodextrin cavity. Ruthenium, osmium, and iridium polypyridyl complexes are particularly attractive …

Targeted Drug Delivery Systems For Cancer Therapy, Antonio Clementi, Christine O'Connor, Mary Mcnamara, A. Mazzaglia, M. C. Aversa, A. Giuffrida

Conference Papers

The role of cyclodextrin’s (CD) in drug delivery has advanced in recent years and this may be attributed to its biocompatibility and well established synthesis. Chemical modification of CDs has shown to extend the physicochemical properties and the host capacity for a variety of drugs. β-CD has been widely used in the early stages of pharmaceutical applications because of its ready availability and its cavity size suitability for a wide range of drugs. Chemical modification of β-CD has proven to enhance aqueous solubilisation, microbiological stability and reduced toxicity in previous studies.1 Folate Receptors are over-expressed in several human cancers including …

The Transport Of Cosmic Rays In Self‐Excited Magnetic Turbulence, Brian Reville, Stephen O'Sullivan, Peter Duffy, John Kirk

Articles

The process of diffusive shock acceleration relies on the efficacy with which hydromagnetic waves can scatter charged particles in the precursor of a shock. The growth of self-generated waves is driven by both resonant and non-resonant processes. We perform high-resolution magnetohydrodynamic simulations of the non-resonant cosmic ray driven instability, in which the unstable waves are excited beyond the linear regime. In a snapshot of the resultant field, particle transport simulations are carried out. The use of a static snapshot of the field is reasonable given that the Larmor period for particles is typically very short relative to the instability growth …

Real-Time Plasma Controlled Chemistry In A Two-Frequency, Confined Plasma Etcher, Vladimir Milosavljevic, Albert R. Ellingboe, Cezar Gaman, John V. Ringwood

Articles

The physics issues of developing model-based control of plasma etching are presented. A novel methodology for incorporating real-time model-based control of plasma processing systems is developed. The methodology is developed for control of two dependent variables (ion flux and chemical densities) by two independent controls (27 MHz power and O2flow). A phenomenological physics model of the nonlinear coupling between the independent controls and the dependent variables of the plasma is presented. By using a design of experiment, the functional dependencies of the response surface are determined. In conjunction with the physical model, the dependencies are used to deconvolve the sensor …

Implications Of The Hall Effect For Turbulent Molecular Clouds, Turlough Downes, Stephen O'Sullivan

Conference papers

No abstract provided.

Numerical Modeling Of Weakly Ionized Plasmas, Stephen O'Sullivan, Turlough Downes

Conference papers

No abstract provided.

Metal Coordination And Cis-Trans Isomerisation Of Benzene Dihydrodiols, Catriona O'Meara

Masters

Abstract In this thesis, a viable route for conversion of arene cis-dihydrodiols to their trans isomers was investigated. The cis-dihydrodiols can be produced by large scale fermentation but their trans analogues are not accessible using this approach. The trans dihydrodiols are potentially important chiral building blocks in synthetic chemistry particularly because they have the advantage that they are more stable than the cis-isomers. The principal aim of this work was to carry out parallel studies to inform the development of the synthetic pathway under study by; (a) synthesis of organometallic and organic intermediates and products and, (b) investigation of the …

Quantification Of The Environmental Solar Ultraviolet Radiation Field At The Human Eye And The Investigation Of Peripherally Focused Rays., David P. Fleming

Doctoral

The increase of terrestrial solar ultraviolet radiation (UVR) due to the reduction of the ozone layer has promoted a variety of research into establishing the impact of this elevated potential dose of UVR on biological tissues. Anterior ocular tissues such as the cornea have been found to be susceptible to damage by terrestrial solar UVR and diseases such as pterygium are commonly thought to be a direct result of absorbed UVR at the nasal limbus. There is a need for more accurate quantification and localisation of incident UVR at the anterior ocular surface. A novel solar blind photodiode sensor array …

Waveguide Fabrication In Uv-Photocurable Sol–Gel Materials: Influence Of The Photoinitiating System, D.L. Versace, Mohamed Oubaha, R. Copperwhite, C. Croutxé-Barghorn, B.D. Maccraith

Articles

In this paper we identify and explain the different chemical interactions involved between a sol–gel matrix and photoinitiators used in the fabrication of optical waveguides. A well-established sol–gel matrix composed of 3-methacryloxypropyltrimethoxysilane, zirconium n-propoxide and methacrylic acid was developed, and two different photoinitiators (Irgacure® 819 and 1800) were added to the host matrix. Optical microscopy was used to characterise the structure of the waveguides as a function of the photoinitiator nature and concentration, and aging of the hybrid sol–gel material. It is clearly demonstrated that the width of the waveguides is strongly influenced by the sol aging. Furthermore, it is …

Knowledge Management For Disparate Etruscan Cultural Heritage, John Mcauley, James Carswell

Conference papers

This paper introduces the TARCHNA approach to managing and presenting contextualised heritage content. The system uses the CIDOC CRM ontology to consolidate a virtual repository of geographically disparate heritage databases and present a holistic view of a fragmented heritage. While previous approaches to presenting heritage collections have focused on the browse and search paradigm, the TARCHNA system uses narrative concepts as a means of presenting and re-using contextualised heritage artefacts within a broader cultural setting.

Interacting Jets From Binary Protostars, Gareth Murphy, Thibaut Lery, Stephen O'Sullivan, Daniel S. Spicer, Francesca Bacciotti, Alex Rosen

Articles

Aims. We investigate potential models that could explain why multiple proto-stellar systems predominantly show single jets. During their formation, stars most frequently produce energetic outflows and jets. However, binary jets have only been observed in a very small number of systems. Methods. We model numerically 3D binary jets for various outflow parameters. We also model the propagation of jets from a specific source, namely L1551 IRS 5, known to have two jets, using recent observations as constraints for simulations with a new MHD code. We examine their morphology and dynamics, and produce synthetic emission maps. Results. We find that the …

A Visual Indication Of Environmental Humidity Using A Colour Changing Hologram Recorded In A Self-Developing Photopolymer, Izabela Naydenova, Raghavendra Jallapuram, Vincent Toal, Suzanne Martin

Articles

A reflection hologram for visual indication of environmental humidity has been studied. The hologram is recorded in a self-developing photopolymer and changes colour when exposed to a change in humidity and is fully reversible. The range of colour change, reversibility and the response time of the hologram have been studied in a controlled humidity environment. Fully reversible holograms with response times from few seconds to tens of minutes have been designed. Extremely sensitive bright visual humidity indicators, capable of dramatic colour change within a few seconds of breathing on them are demonstrated.

Optimising Design Parameters Of Enzyme-Channelling Biosensors, Dana Mackey, Tony Killard

Conference Papers

Two mathematical models for an electrochemical biosensor are proposed and compared with a view to determining the ratio of two immobilized enzymes which maximizes the amperometric signal amplitude.