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Technological University Dublin

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2014

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Articles 1 - 30 of 98

Full-Text Articles in Physical Sciences and Mathematics

Diffractive Optical Elements With A Large Angle Of Operation Recorded In Acrylamide Based Photopolymer On Flexible Substrates, Hoda Akbari, Izabela Naydenova, Lina Persechini, Sean Garner, Pat Cimo, Suzanne Martin Dec 2014

Diffractive Optical Elements With A Large Angle Of Operation Recorded In Acrylamide Based Photopolymer On Flexible Substrates, Hoda Akbari, Izabela Naydenova, Lina Persechini, Sean Garner, Pat Cimo, Suzanne Martin

Articles

A holographic device characterised by a large angular range of operation is under development. The aim of this study is to increase the angular working range of the diffractive lens by stacking three layers of high efficiency optical elements on top of each other so that light is collected (and focussed) from a broader range of angles. The angular range of each individual lens element is important, and work has already been done in an acrylamide-based photosensitive polymer to broaden the angular range of individual elements using holographic recording at a low spatial frequency.This paper reports new results on the …


Antimicrobial Properties Of Nano-Silver: A Cautionary Approach To Ionic Interference, Kate Sheehy, Alan Casey, Anna Murphy, Gordon Chambers Dec 2014

Antimicrobial Properties Of Nano-Silver: A Cautionary Approach To Ionic Interference, Kate Sheehy, Alan Casey, Anna Murphy, Gordon Chambers

Articles

Hypothesis: Metallic nanoparticles such as nano-silver have found many applications as alternative antimicrobials in recent years. However methods for determining their proposed antimicrobial activity have received little attention to date. The disk diffusion assay is commonly used as a demonstration of antimicrobial properties and is a regular feature in synthetic nanoparticle papers. The aim of this study was to assess its effectiveness in demonstrating the ‘‘nanoparticle specific’’ antimicrobial properties in the absence of ionic contributions from unreacted reducing agents and or impurities. Experiments: The disk diffusion assay was carried out on a range of silver nanoparticles, both in-house synthesised and …


Competitive Evaluation Of Data Mining Algorithms For Use In Cassification Of Leukocyte Subtypes With Raman Microspectroscopy, Adrian Maguire, I. Vega-Carrascal, Jane Bryant, Lisa White, Orla Howe, Fiona Lyng, Aidan Meade Dec 2014

Competitive Evaluation Of Data Mining Algorithms For Use In Cassification Of Leukocyte Subtypes With Raman Microspectroscopy, Adrian Maguire, I. Vega-Carrascal, Jane Bryant, Lisa White, Orla Howe, Fiona Lyng, Aidan Meade

Articles

Raman microspectroscopy has been investigated for some time for use in label-free cell sorting devices. These approaches require coupling of the Raman spectrometer to complex data mining algorithms for identification of cellular subtypes such as the leukocyte subpopulations of lymphocytes and monocytes. In this study, three distinct multivariate classification approaches, (PCA-LDA, SVMs and Random Forests) are developed and tested on their ability to classify the cellular subtype in extracted peripheral blood mononuclear cells (T-cell lymphocytes from myeloid cells), and are evaluated in terms of their respective classification performance. A strategy for optimisation of each of the classification algorithm is presented …


Thermal Comfort, Energy Usage And Fuel Poverty In A Sample Of Older Person’S Households In Dublin, Eugene Monahan Dec 2014

Thermal Comfort, Energy Usage And Fuel Poverty In A Sample Of Older Person’S Households In Dublin, Eugene Monahan

Masters

This research was conducted in twenty nine Dublin City Council senior citizen sheltered housing dwellings. Temperature (°C) and relative humidity (% RH) was recorded inside all dwellings using data loggers over two separate monitoring periods of four months between December and March of 2011-2012 and 2012-2013. Energy usage including gas and electricity was also recorded for each dwelling during both monitoring periods. Outside ambient temperature data for both periods was acquired from Met Eireann. A dwelling occupant questionnaire was completed to obtain relevant technical, social and behavioural data, and to establish the prevalence of fuel poverty amongst the sample. The …


Raman Microspectroscopy For The Early Detection Of Pre-Malignant Changes In Cervical Tissue, Nosheen Rashid, Haq Nawaz, Kelvin W. Poon, Franck Bonnier, Salih Bakhiet, Cara Martin, John O'Leary, Hugh Byrne, Fiona Lyng Dec 2014

Raman Microspectroscopy For The Early Detection Of Pre-Malignant Changes In Cervical Tissue, Nosheen Rashid, Haq Nawaz, Kelvin W. Poon, Franck Bonnier, Salih Bakhiet, Cara Martin, John O'Leary, Hugh Byrne, Fiona Lyng

Articles

Cervical cancer is the third most common cancer affecting women worldwide. The mortality associated with cervical cancer can, however, be significantly reduced if the disease is detected at the pre-malignant stage. The aim of this study was to evaluate the potential of Raman microspectroscopy for elucidation of the biochemical changes associated with the pre-malignant stages of cervical cancer. Formalin fixed paraffin preserved tissue sections from cervical biopsies classified as negative for intraepithelial lesion and malignancy (NILM), low grade squamous intraepithelial lesion (LSIL) or high grade squamous intraepithelial lesion (HSIL) were analysed by Raman spectral mapping. Raman mapping, with K-Means Cluster …


An Agile Implementation Within A Medical Device Software Organisation, Martin Mchugh, Fergal Mc Caffery, Garret Coady Nov 2014

An Agile Implementation Within A Medical Device Software Organisation, Martin Mchugh, Fergal Mc Caffery, Garret Coady

Conference papers

Three surveys conducted over a 6 year period revealed that medical device software organisations have difficulties in the area of requirements management, namely accommodating changes in requirements. Medical device software is traditionally developed in accordance with a plan driven software development lifecycle (SDLC). These SDLCs are rigid and inflexible to changes once the requirements management stage has been completed. Agile methods are gaining momentum in non-regulated industries but as of yet, the adoption of these methods in regulated industries such as the medical device software domain remains low. This study presents an implementation of agile methods within a medical device …


Online Resource Platform For Mathematics Education, Marisa Llorens, Edmund Nevin, Eileen Mageean Oct 2014

Online Resource Platform For Mathematics Education, Marisa Llorens, Edmund Nevin, Eileen Mageean

Conference papers

Engineering education is facing many challenges: a decline in core mathematical skills; lowering entry requirements; and the diversity of the student cohort. One approach to confronting these challenges is to make subject content appropriate to the communication styles of today’s student. To achieve this, a pedagogical shift from the traditional hierarchical approach to learning to one that embraces the use of technology as a tool to enhance the student learning experience is required. By including the student as co-creator of course content, a greater sense of engagement is achieved and a change to one where students become agents of their …


Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick Cullen, Paula Bourke Sep 2014

Quantitative Assessment Of Blood Coagulation By Cold Atmospheric Plasma, Caitlin Heslin, Daniela Boehm, Vladimir Milosavljevic, Michelle Laycock, Patrick Cullen, Paula Bourke

Articles

Cold atmospheric plasma (CAP) is produced by ionizing a chosen gas, thereby creating charged and reactive species. The reactive species generated are capable of inducing a range of biomedically relevant interactions including blood coagulation. However, the underlying biochemical processes of plasma-assisted blood coagulation are largely unknown, and data quantifying blood clot formation or the impact of system parameters on the intensity of the blood clot are scarce. In this study, blood coagulation was quantified by measuring hemoglobin absorbance. System parameters of the kINPen plasma jet were investigated and compared, including treatment time, distance from the plasma source and gas flow …


What Is Nanoscience?' - A Hermeneutic Phenomenological Study Of Nanoscience Researchers' Experiences, Deepa Chari Sep 2014

What Is Nanoscience?' - A Hermeneutic Phenomenological Study Of Nanoscience Researchers' Experiences, Deepa Chari

Doctoral

Nanoscience and nanotechnology have been described as a research area that integrates many scientific and engineering disciplines. However, the integration of disciplines is so complex that the disciplinarity of nanoscience and nanotechnology remains undefined. As a result, the nanoscience and nanotechnology area is viewed as multidisciplinary, or interdisciplinary science, or even as a separate discipline and there is no consensus regarding its disciplinarity. The previous studies conducted in order to describe the disciplinarity associated with this area have focused mainly on political, institutional and external factors while the cognitive aspects of disciplinarity of nanoscience and nanotechnology are still less understood. …


An Assessment Of The Energy Generation Potential Of Photovoltaic Systems In Cameroon Using Satellite-Derived Solar Radiation Datasets, Lacour Ayompe, Aidan Duffy Sep 2014

An Assessment Of The Energy Generation Potential Of Photovoltaic Systems In Cameroon Using Satellite-Derived Solar Radiation Datasets, Lacour Ayompe, Aidan Duffy

Articles

Cameroon like most developing countries does not have a reliable network of surface observation stations for collecting weather data. This has been a major drawback for accurate assessment of the energy generation potential of photovoltaic systems in Cameroon. A viable alternative is to obtain site-specific solar irradiation from satellite-derived datasets. In this paper, the energy output, capacity factor and performance ratio of photovoltaic systems in 33 locations spread around ten regions in Cameroon have been evaluated using monthly average daily global horizontal solar irradiation from long-term satellitederived data available in Solar GIS software. An economic assessment revealed that a simple …


The Role Of Emotional And Facial Expression In Synthesised Sign Language Avatars, Robert G Smith Sep 2014

The Role Of Emotional And Facial Expression In Synthesised Sign Language Avatars, Robert G Smith

Other Resources

This thesis explores the role that underlying emotional facial expressions might have in regards to understandability in sign language avatars. Focusing specifically on Irish Sign Language (ISL), we examine the Deaf community’s requirement for a visual-gestural language as well as some linguistic attributes of ISL which we consider fundamental to this research. Unlike spoken language, visual-gestural languages such as ISL have no standard written representation. Given this, we compare current methods of written representation for signed languages as we consider: which, if any, is the most suitable transcription method for the medical receptionist dialogue corpus. A growing body of work …


Dressing Method And Quadratic Bundles Related To Symmetric Spaces: Vanishing Boundary Conditions, Tihomir Valchev Sep 2014

Dressing Method And Quadratic Bundles Related To Symmetric Spaces: Vanishing Boundary Conditions, Tihomir Valchev

Articles

We consider quadratic bundles related to Hermitian symmetric spaces of the type SU(m+n)/S(U(m) x U(n)). The simplest representative of the corresponding integrable hierarchy is given by a multi-component Kaup-Newell derivative nonlinear Schroedinger equation which serves as a motivational example for our general considerations. We extensively discuss how one can apply Zakharov-Shabat's dressing procedure to derive reflectionless potentials obeying zero boundary conditions. Those could be used for one to construct fast decaying solutions to any nonlinear equation belonging to the same hierarchy. One can distinguish between generic soliton type solutions and rational solutions.


A Soft Condensed Matter Approach Towards Mathematical Modelling Of Mass Transport And Swelling In Food Grains, Michael Chapwanya, N. Misra Aug 2014

A Soft Condensed Matter Approach Towards Mathematical Modelling Of Mass Transport And Swelling In Food Grains, Michael Chapwanya, N. Misra

Articles

Soft condensed matter (SCM) physics has recently gained importance for a large class of engineering materials. The treatment of food materials from a soft matter perspective, however, is only at the surface and is gaining importance for understanding the complex phenomena and structure of foods. In this work, we present a theoretical treatment of navy beans from a SCM perspective to describe the hydration kinetics. We solve the transport equations within a porous matrix and employ the Flory–Huggin’s equation for polymer–solvent mixture to balance the osmotic pressure. The swelling of the legume seed is modelled as a moving boundary with …


One-Dimensional Weakly Nonlinear Model Equations For Rossby Waves, David Henry, Rossen Ivanov Aug 2014

One-Dimensional Weakly Nonlinear Model Equations For Rossby Waves, David Henry, Rossen Ivanov

Articles

In this study we explore several possibilities for modelling weakly nonlinear Rossby waves in fluid of constant depth, which propagate predominantly in one direction. The model equations obtained include the BBM equation, as well as the integrable KdV and Degasperis-Procesi equations.


The Social And Economic Impact Of Refractive Error In Mozambique, Stephen James Thompson Aug 2014

The Social And Economic Impact Of Refractive Error In Mozambique, Stephen James Thompson

Doctoral

The purpose of this thesis is to investigate potential key determinants of the success, or otherwise, of endeavours to address avoidable Visual Impairment (VI) by addressing Uncorrected Refractive Error (URE) in Mozambique and the wider region of sub-Saharan Africa by providing optometric services. It includes a Cost Benefit Analysis (CBA) of a higher education optometry training programme, barriers that might prevent the realisation of overarching goals despite a successful training programme, and a Willingness to Pay (WTP) analysis to inform the pricing structure and to determine the financial sustainability of the system. Methods A standard CBA methodology was applied to …


Multi-Valued Argumentation Frameworks, Pierpaolo Dondio Aug 2014

Multi-Valued Argumentation Frameworks, Pierpaolo Dondio

Conference papers

In this paper we explore how the seminal Dung’s abstract argumentation framework can be extended to handle arguments containing gradual concepts. We allow arguments to have a degree of truth associated with them and we investigate the degree of truth to which each argument can be considered accepted, rejected and undecided by an abstract argumentation semantics. We propose a truth-compositional recursive computation, and we discuss examples using the major multi-valued logics such as Godel’s, Zadeh’s and Łukasiewicz's logic. The findings are a contribution in the field of non-monotonic approximate reasoning and they also represent a well-grounded proposal towards the introduction …


Developments Of Cobalt Ferrite Nanoparticles Prepared By The Sol–Gel Process, M. Sajjiaa, Mohamed Oubaha, M. Hasanuzzaman, A.G. Olabi Jun 2014

Developments Of Cobalt Ferrite Nanoparticles Prepared By The Sol–Gel Process, M. Sajjiaa, Mohamed Oubaha, M. Hasanuzzaman, A.G. Olabi

Articles

In the phase of the study reported, the sol–gel technique was followed in the preparation of cobalt ferrite amorphous powder following the same procedure which was selected as the best approach as described in a previous study. It was assumed that there must be a correlation between the heat treatment operational parameters and the structural properties of the material being synthesized. Similarly, it was understood that some heat treatment is necessary to completely decompose the organic and nitrate contents present in the amorphous powder. Having ensured that the heat treatment parameters could be changed without producing a material with poorer …


Entropy, Information, Landauer’S Limit And Moore’S Law, Paul Tobin, Jonathan Blackledge Jun 2014

Entropy, Information, Landauer’S Limit And Moore’S Law, Paul Tobin, Jonathan Blackledge

Conference papers

In this paper we explore the link between information and entropy by considering the infamous Maxwell demon thought experiment. A non-rigorous mathematical solution by Le´o Szil´ard established this link for the first time, as did Claude Shannon nineteen years later. In 1961, Rolf Landauer’s mathematical solution resulted in the Landauer limit, which is still being hotly debated, but here we discuss the implication of this limit on Moore’s law and future growth in computing power. A workaround the limit is proposed using an Analogue Artificial Neural Network (AANN). Here, we mimic the action of a human brain synapse formed from …


Work In Progress: Online Resource Platform For Mathematics Education, Marisa Llorens, Edmund Nevin, Eileen Mageean Jun 2014

Work In Progress: Online Resource Platform For Mathematics Education, Marisa Llorens, Edmund Nevin, Eileen Mageean

Conference papers

Mathematics is intrinsic to engineering and as such plays an integral role in the education of engineers. New challenges are being faced in higher education particularly in the areas of student motivation, engagement and attainment. As a result mathematics is often the focus of engineering education research. Traditional methods of delivery such as lectures and tutorials need to evolve to counter these challenges with new pedagogical approaches explored including the use of new technologies. Today’s students are immersed in an increasingly technological world and are willing to adapt to new technological advances. This paper describes a study being undertaken in …


Studies On The Synthesis Of Orthogonally Protected Azalanthionines, And Of Routes Towards B-Methyl Azalanthionines, By Ring-Opening Of N-Activated Aziridine-2-Crboxylates, Keith O'Brien, Keith Ó Proinsias, Fintan Kelleher Jun 2014

Studies On The Synthesis Of Orthogonally Protected Azalanthionines, And Of Routes Towards B-Methyl Azalanthionines, By Ring-Opening Of N-Activated Aziridine-2-Crboxylates, Keith O'Brien, Keith Ó Proinsias, Fintan Kelleher

Articles

Orthogonally protected azalanthionines were successfully synthesised by the ring-opening of N-activated aziridine-2-carboxylates with protected diaminopropanoic acids (DAPs). The required DAPs were also prepared by ring-opening of N-activated aziridine-2-carboxylates with para-methoxybenzylamine, but it was found that the choice of aziridine protecting groups dictated both the success of the reaction as well as the regioselectivity of the isolated products. Attempts to extend the methodology to the preparation of the more sterically demanding b-methyl azalanthionines have, so far, been unsuccessful.


Free Energies In A General Non-Local Theory Of A Material With Memory, Giovambattista Amendola, Mauro Fabrizio, John Murrough Golden Jun 2014

Free Energies In A General Non-Local Theory Of A Material With Memory, Giovambattista Amendola, Mauro Fabrizio, John Murrough Golden

Articles

A general theory of non-local materials, with linear constitutive equations and memory effects, is developed within a thermodynamic framework. Several free energy and dissipation functionals are constructed and explored. These include an expression for the minimum free energy and a functional that is a free energy for important categories of memory kernels and is explicitly a functional of the minimal state. The functionals discussed have a similar general form to the corresponding expressions for simple materials. A number of new results are derived for them, most of which apply equally to both types of material. In particular, detailed formulae are …


Metal-Organic Frameworks Based On Pyridyl-Tetrazole Ligands Containing Ester Or Carboxylate Pendant Arms, Ursula Sheridan, John Gallagher, Morten Bjerrum, Adrienne Fleming, Fintan Kelleher, John Mcginley May 2014

Metal-Organic Frameworks Based On Pyridyl-Tetrazole Ligands Containing Ester Or Carboxylate Pendant Arms, Ursula Sheridan, John Gallagher, Morten Bjerrum, Adrienne Fleming, Fintan Kelleher, John Mcginley

Articles

The coordination of pyridyl-tetrazole derivatives containing ester substituents, at either the N-1 or N-2 position of the tetrazole ring, with copper(II) chloride results in the formation of either 1:1 or 1:2 copper to ligand complexes, depending on the ligand. However, when the ester functionality is changed to a carboxylate group, the resulting complexation reactions yield metal-organic frameworks. The resulting structures vary dramatically in pore size, depending on both reaction solvents and position of carboxylate group on the tetrazole ring. Despite the presence of sodium cations in the reaction mixtures, no sodium incorporation was ever observed in any of the complexes. …


Free Energies For Materials With Memory In Terms Of State Functionals, John Murrough Golden May 2014

Free Energies For Materials With Memory In Terms Of State Functionals, John Murrough Golden

Articles

Abstract The aim of thiswork is to determinewhat free energy functionals are expressible as quadratic forms of the state functional It which is discussed in earlier papers. The single integral form is shown to include the functional wF proposed a few years ago, and also a further category of functionals which are easily described but more complicated to construct. These latter examples exist only for certain types of materials. The double integral case is examined in detail, against the background of a newsystematic approach developed recently for double integral quadratic forms in terms of strain history, which was used to …


Development Of A Novel Hybrid Aluminum-Based Sol-Gel Materials: Application To The Protection Of Aa2024-T3 Alloys In Alkaline Environment, Mohamed Oubaha, Padinchare Covilakath Rajath Varma, Brendan Duffy, Zuhair Mattoug Gasem, Steven J. Hinder May 2014

Development Of A Novel Hybrid Aluminum-Based Sol-Gel Materials: Application To The Protection Of Aa2024-T3 Alloys In Alkaline Environment, Mohamed Oubaha, Padinchare Covilakath Rajath Varma, Brendan Duffy, Zuhair Mattoug Gasem, Steven J. Hinder

Articles

Extensive research on environmentally complaint sol-gel coatings is currently underway for a wide range of applications. Sol-gel technology combines the synergistic properties of inorganic and organic components to design nanostructured coating materials with advanced physical properties. Through a judicious choice of precursors and additives improved performances, such as chemical resistance or pH stability, it can be achieved. This is of particular interest for copper rich AA 2024-T3 aluminium alloys used on aircraft, where increase in local pH occurs at corrosion sites. This work focuses on improving the alkaline stability and anticorrosion properties of such a sol-gel coatings on AA2024-T3 by …


Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper May 2014

Selection Of The Process Parameters For The Mass Plating Of Discrete Electronic Components, Ann Hopper

Articles

The miniaturisation of electronic components coupled with requirements for high temperature lead free soldering has forced the improvement of the termination finish of surface mount components to meet the critical demands of the electronic industry. In the present work the processing parameters necessary to plate miniature multilayer varistors (MLV’s) have been explored. The tooling selected was a “Rotary flow-thru’ plater” which achieved high volume plating with


Dynamic Estimation Of Rater Reliability Using Multi-Armed Bandits, Alexey Tarasov May 2014

Dynamic Estimation Of Rater Reliability Using Multi-Armed Bandits, Alexey Tarasov

Doctoral

One of the critical success factors for supervised machine learning is the quality of target values, or predictions, associated with training instances. Predictions can be discrete labels (such as a binary variable specifying whether a blog post is positive or negative) or continuous ratings (for instance, how boring a video is on a 10-point scale). In some areas, predictions are readily available, while in others, the eort of human workers has to be involved. For instance, in the task of emotion recognition from speech, a large corpus of speech recordings is usually available, and humans denote which emotions are present …


Adopting Agile Practices When Developing Software For Use In The Medical Domain, Martin Mchugh, Fergal Mccaffery, Valentine Casey May 2014

Adopting Agile Practices When Developing Software For Use In The Medical Domain, Martin Mchugh, Fergal Mccaffery, Valentine Casey

Articles

Non-safety critical software developers have been reaping the benefits of adopting agile practices for a number of years. However, developers of safety critical software often have concerns about adopting agile practices. Through performing a literature review, this research has identified the perceived barriers to following agile practices when developing medical device software. A questionnaire based survey was also conducted with medical device software developers in Ireland to determine the barriers to adopting agile practices. The survey revealed that half of the respondents develop software in accordance with a plan driven software development lifecycle and that they believe that there are …


Economic, Energy And Ghg Emissions Performance Evaluation Of A Whispergen Mk Iv Stirling Engine Μ-Chp Unit In A Domestic Dwelling, Gerry Conroy, Aidan Duffy, Lacour Ayompe May 2014

Economic, Energy And Ghg Emissions Performance Evaluation Of A Whispergen Mk Iv Stirling Engine Μ-Chp Unit In A Domestic Dwelling, Gerry Conroy, Aidan Duffy, Lacour Ayompe

Articles

This paper presents an assessment of the energy, economic and greenhouse gas emissions performances of a WhisperGen Mk IV Stirling engine μ-CHP unit for use in a conventional house in the Republic of Ireland. The energy performance data used in this study was obtained from a field trial carried out in Belfast, Northern Ireland during the period June 2004 - July 2005 by Northern Ireland Electricity and Phoenix Gas working in collaboration with Whispertech UK. A comparative performance analysis between the µ-CHP unit and a condensing gas boiler revealed that the µ-CHP unit resulted in an annual cost saving of …


Microfiber Coupler Based Label-Free Immunosensor, Lin Bo, Christy Charlton O'Mahony, Yuliya Semenova, Niamh Gilmartin, Pengfei Wang, Gerald Farrell Apr 2014

Microfiber Coupler Based Label-Free Immunosensor, Lin Bo, Christy Charlton O'Mahony, Yuliya Semenova, Niamh Gilmartin, Pengfei Wang, Gerald Farrell

Articles

Optical microfibers and related structures which incorporate large evanescent field and minimal size offer new opportunities for biosensing applications. In this paper we report the development of an immunosensor based on a tapered microfiber coupler embedded in a low refractive index polymer. Biomolecules adsorbed on the microfiber coupler surface modify the surrounding refractive index. By immobilizing antigens on the surface of the sensing area, the microfiber coupler was able to operate as a label-free immunosensor to detect specific antibodies. We experimentally demonstrated for the first time the sensing ability of this sensor using a fibrinogen antigen-antibody pair. By monitoring the …


Euler-Poincar´E Equations For G-Strands, Darryl Holm, Rossen Ivanov Mar 2014

Euler-Poincar´E Equations For G-Strands, Darryl Holm, Rossen Ivanov

Conference papers

The G-strand equations for a map R×R into a Lie group G are associated to a G-invariant Lagrangian. The Lie group manifold is also the configuration space for the Lagrangian. The G-strand itself is the map g(t,s):R×R→G, where t and s are the independent variables of the G-strand equations. The Euler-Poincar'e reduction of the variational principle leads to a formulation where the dependent variables of the G-strand equations take values in the corresponding Lie algebra g and its co-algebra, g with respect to the pairing provided by the variational derivatives of the Lagrangian. We review examples of different G-strand …