Conference papers

Practical Analysis of Key Electrical Interfaces for Wave Energy Converter Arrays

Fergus Sharkey et al. — Thu, 10 Jan 2013 02:12:04 PST

The authors have previously outlined a proposed path for the development of electrical networks for deepwater wave farms. This path broadly followed that of offshore wind farms as the least cost solution. The main differences between wind farm and wave farm electrical networks were identified as the method of installation and maintenance and the components at the WEC interface with the electrical network. Components such as dynamic cables, submarine connectors, submarine switchgear all form part of these interfaces. This paper examines the key electrical interfaces for WEC arrays such as the dynamic cable to WEC interface, dynamic cable to static cable interface, and the WEC medium voltage switchgear interface. The cost and functionality of these interfaces are evaluated for a variety of options. The paper also looks at array electrical configurations beyond radial under the same criteria. The paper concludes with an optimised solution for the key interfaces between the WEC and the electrical which minimises cost but maintains important functionality of the electrical network within the array. The preferred solution uses a combination of permanent cable joints, mateable connectors, and onboard switchgear. The paper outlines the challenge to get the electrical systems to a cost level that will be competitive with other renewable sources, particularly offshore wind.

Voltage Flicker Evaluation for Wave Energy Converters – Assessment Guidelines

Fergus Sharkey et al. — Thu, 10 Jan 2013 02:12:02 PST

Voltage flicker is a power quality problem caused by regularly oscillating active and reactive power either from a load or generator. The regular power oscillations induce a voltage change at the grid connection which is proportional to the amplitude of the power oscillation and at the same frequency. The impedance of the grid (grid strength) at the point of connection is a factor in the amplitude of the voltage oscillation. The frequency band of interest for flicker evaluation is from 0.01-20Hz, and is most severe at 8.8Hz. The frequency of the primary resource for wave energy converters lies within this range. Therefore the coupling of the input resource to the output power of a wave energy converter will cause voltage flicker at the point of connection. This is particularly true for ‘direct drive’ wave energy converters. This paper serves to establish the flicker effects of wave energy converters on the grid voltage. The paper outlines some working guidelines for the evaluation of flicker from a device. The paper concludes that wave energy converters may exceed flicker emission limits, particularly in weak grid areas and suggests some strategies for overcoming this problem.

Facilitating Intellectual and Personal Skills Development in Engineering Programmes

Gavin Duffy — Mon, 03 Dec 2012 09:43:21 PST

Engineering graduates are under increasing pressure to demonstrate high levels of personal skills. The accreditation criteria of professional bodies such as the Accreditation Board for Engineering and Technology (ABET) in the US, Engineers Ireland and Engineers Australia, to name but a few, now include the development of a broad range of personal skills (ABET, 2008; Engineers Australia, 2011; Engineers Ireland, 2007). Evidence of a ‘strong contribution’, a term used by Engineers Ireland, to the development of teamwork, lifelong learning, ethics, communication and self-direction is required in the programme to satisfy the accreditation criteria. Numerous anecdotes of intensive probing for personal skills are relayed by graduates applying for their first job. Many employers devote significant time to assessing the level of personal skills during the recruitment process. Government reports on skills needs often call for greater attention to be paid to the development of critical thinking, creativity and innovation in engineering programmes (Forfás, 2009). Today’s engineering students are experiencing the effects of curricula changing in response to this new outlook of graduate attributes. Achievement of high levels of many personal skills is greatly facilitated by a concurrent growth in intellectual development – autonomy in learning, commitment to ethics, willingness to lead and display initiative are hallmarks of the relativistic thinker. The engineer whose intellectual development has not yet passed the dualistic and multiplistic stages and is still reliant on authority for direction and decision making will not score highly on personal skills, will be unattractive to employers, and has yet to realise his/her potential. Personal skills development will be facilitated by an engineering curriculum that promotes growth in intellectual development. Attention should be paid to the intellectual development of the students throughout the programme to optimise their progression from dualistic to relativistic thinking. Process facilitated student-centred learning can support this growth. Evidence of strong contribution to programme outcomes related to design and personal skills should also come from measurements of levels of intellectual development among students.

Improving Engineering Students’ Design Skills in a Project-Based Learning Course by Addressing Epistemological Issues

Gavin Duffy et al. — Mon, 03 Dec 2012 08:17:29 PST

A novice designer is prone to making premature decisions. Rather than explore issues and research information and options, he may quickly jump to posing solutions and view design as a linear, step-by-step process. Instead of testing a variety of ideas, a beginning designer often becomes mesmerized by his initial ideas. An experienced designer, on the other hand, is much more likely conduct research and delay making decisions until the challenge has been fully explored [1]. She uses a variety of techniques to generate ideas, test them, and see how they inter-relate, sees design as an iterative process, has a variety of approaches, integrates feedback and reflects on the design process. She uses rational inquiry to cross-reference and integrate ideas, information, and personal experience. Such behaviour reflects beliefs about knowledge and its creation and such actions are hallmarks of the relativistic thinker [5] who can set goals, reflect on thinking, identify what is needed and understand why it is necessary. Although the individual seeks new experiences and multiple views, she also seeks to achieve well-integrated solutions that are simple (as opposed to simplistic). This person is able to confront discontinuities and paradoxes, ask key questions, resolve key dilemmas, and generate new insights. According to Belenky et al. [7], such a person is inherently reflective, passionate about knowing, and willing to struggle to achieve balance. The novice and expert enact very different personal epistemologies, in particular how they view themselves as sources of knowledge, how they justify decisions and view knowledge as fixed or tentative[1].

In this study, we explore how personal epistemology influences the design process in the context of a project-based learning (PBL) module in which students are asked to design, build and test simple measurement systems to create a weather station. The curriculum is largely traditional in nature but has seen a small but significant increase in the amount of PBL in the last few years. Many, often competing, decisions must be made by the students throughout this module, for example when designing the signal conditioning circuits or choosing the variables, and many can rush through this process, failing to justify their choices and making decisions for arbitrary reasons. Were they to pay more attention to the decision making process the students, with little extra work, could engage more fully with the module, produce better artifacts and achieve higher grades. In this paper we argue prior knowledge and motivation, other key drivers of the learning process along with epistemology [2], are not the reasons why some students lacked independence and failed to justify many of their decisions in this module.

[1] S. Chance discusses these topics in greater detail in another paper included in this set of proceedings.

A Quality Control System using Texture Analysis in Metallurgy

Jonathan Blackledge et al. — Fri, 23 Nov 2012 06:58:05 PST

Object detection, recognition and texture classification is an important aspect of many industrial quality control systems. In this paper, we report on a system designed for the inspection of surfaces which has a range of applications in the area of metallurgy. The approach considered is based on the application of Fractal Geometry and Fuzzy Logic for texture classification and, in this paper, focuses on the manufacture of rolled steel. The manufacture of high quality metals requires automatic surface inspection for the assessment of quality control. Quality control systems are required for several tasks such as screening defected products, monitoring the manufactures process, sorting information for different applications and product certification and grading for end customers. The system discussed in this paper was developed for the Novolipetck Iron and Still Corporation in Russia and tested with images captured at a rolling mill with metal sheets moving at speed of up to six meters per second and inspected for several defect classes. The classification method used is based on the application of a set of features which include fractal parameters such as the Lacunarity and Fractal Dimension thereby incorporating the characterisation of surface surfaces in terms of their texture. The principal issues associated with texture recognition are presented which includes fast segmentation algorithms. The self-learning procedure for designing a decision making engine using fuzzy logic and membership function theory is also presented and a new technique for the creation and extraction of information from a membership function considered. The methods discussed, and the system developed, have a range of applications in ‘machine vision’ and automatic inspection. However, in this publication, we focus on the development and implementation of a surface inspection system that can be used in a iron and steel manufacture by non-experts to the automatic recognition system operators.

Multi-Channel Audio Information Hiding

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:46:31 PST

We consider a method of hiding many audio channels in one host signal. The purpose of this is to provide a ‘mix’ that incorporates information on all the channels used to produce it, thereby allowing all, or, at least some channels to be stored in the mix for later use. After providing an overview of some recently published audio water marking schemes in the time and transform domains, we present a method that is based on using a four least significant bits scheme to embed five MP3 files into a single 16-bit host stereo WAV file without incurring any perceptual audio distortions in the host data. The hostWAV file is taken to be the final mix associated with the original data before applying ‘lose MP3’ compression or alternatively an arbitrary host audio signal into which other multichannel audio data is hidden. Further, the embedded information can be encrypted and/or the embedding locations randomized on a channel by channel basis depending on the protocol desired by the user. The method is illustrated by providing example m-code for interested readers to investigate and reproduce the results obtained to date and as a basis for further development.

Cable Heating Effects due to Harmonic Distortion in Electrical Installations

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:46:30 PST

The increasing use of non-linear loads in electrical installations has exacerbated the problems of harmonic distortion in industrial and commercial electrical systems. In the UK the current practice to determine the cable size for an electric circuit is to use BS7671. However, previously the 16th edition IEE Wiring Regulations only dealt with situations where cables attain the conductor temperature generated by sinusoidal currents at the fundamental power frequency. This paper outlines the methods available to determine the minimum size of line conductors for protection against overload currents, taking into account the harmonic content of the load current, and explains the harmonic rating factor Cf introduced in 2008 for cables that are under significant harmonic influences. Since the effect of harmonic currents is to increase the joule losses in a cable, the ampacity of the cable will need to be corrected to ensure the maximum conductor operating temperature is not exceeded. An experiment on how cable temperature can be measured under harmonic influence is described, and several sets of measurements taken on a typical cable are analysed. The paper concludes that direct usage of the BS7671 rating factor for harmonics appears to be rather conservative and could lead to over-sizing of the line conductors for three-phase circuits, but is deemed beneficial in the long run.

Wind Turbine Power Quality Estimation Using a Lévy Model for Wind Velocity Data

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:46:29 PST

The power quality of a wind turbine is determined by many factors but time-dependent variation in the wind velocity are arguably the most important. In this paper a non-Gaussian model for the wind velocity is introduced that is based on a Lévy distribution. It is shown how this distribution can be used to derive a stochastic fractional diffusion equation for the wind velocity as a function of time whose solution is characterised by the Lévy index. A numerical method for computing the L´evy index from wind velocity time series is introduced and applied to example wind velocity data for both rural and urban areas where, in the latter case, the index is observed to have a larger value. Finally, an empirical relationship is derived for the power output from a wind turbine in terms of the Lévy index using Betz law.

Magnetic Resonance Image Processing using Levy

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:41:27 PST

We consider the physical nature of the self-diffusion of water molecules in tissue and explore how (Nuclear) Magnetic Resonance (MR) imaging may be used as a means of measuring the rate of diffusion in vivo. A discussion is presented on how these techniques may be implemented as a non-invasive means of assessing the response of tumours to novel therapeutics including some of the basic advantages and disadvan- tages when compared to other methods. The physical basis and mathematical models for diffusion are considered together with models for the distribution of the diffusion co- efficient including a Lévy distributed model. Using a Lévy distributed diffusion model, we develop a novel algorithm for the purpose of improving the signal-to-noise ratio of MR images.

Predicting Currency Pair Trends using the Fractal Market Hypothesis

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:41:26 PST

This paper reports on the results of a research and development pro- gramme concerned with the analysis of currency pair exchange time series for Forex trading in an intensive applications and services environment. In particular, we present some of the preliminary results obtained for Forex trading using MetaTrader 4 with a new set of trend indicators deigned using a mathematical model that is based on the Fractal Market Hypothesis. This includes examples of various currency pair exchange rates considered over di erent time intervals and use of the indicators in a live trading environment to place a buy/sell order.

Forex Trading using MetaTrader 4 with the Fractal Market Hypothesis

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:41:25 PST

This paper reports on the results of a research and development programme concerned with the analysis of currency pair exchange time series for Forex trading in an intensive applications and services environment. In particular, we present some of the preliminary results obtained for Forex trading using MetaTrader 4 with a new set of trend indicators deigned using a mathematical model that is based on the Fractal Market Hypothesis. This includes examples of various currency pair exchange rates considered over different time intervals and use of the indicators in a live trading environment to place a buy/sell order.

On the Applications of Deterministic Chaos for Encrypting Data on the Cloud

Jonathan Blackledge et al. — Fri, 23 Nov 2012 04:41:23 PST

Cloud computing is expected to grow considerably in the future because it has so many advantages with regard to sale and cost, change management, next generation architectures, choice and agility. However, one of the principal concerns for users of the Cloud is lack of control and above all, data security. This paper considers an approach to encrypting information before it is ‘place’ on the Cloud where each user has access to their own encryption algorithm, an algorithm that is based on a set of Iterative Function Systems that outputs a chaotic number stream, designed to produce a cryptographically secure cipher. We study cryptographic systems using finite-state approximations to chaos or ‘pseudo-chaos’ and develop an approach based on the concept of multi-algorithmic cryptography that exploits the properties of pseudo-chaos. Although such algorithms can be taken to be in the public domain in order to conform with the Kerchhoff-Shannon principal, i.e. the enemy knows the system, their combination can be used to secure data in a way that is unique to each user. This provides the potential for users of the Cloud to upload and transfer data in the knowledge that they are encrypting their data in a way that is algorithm as well key dependent, thereby defeating a known algorithm attack. This paper reports on one application of this approach called Crypstic in which the encryption engine is mounted on a USB memory stick and where the key is automatically generated by the characteristics of the plaintext/ciphertext file.

Surveying First-Year Students Prior Conceptual Understanding of Direct Current Resistive Electric Circuits: an Update

Aidan O'Dwyer — Fri, 23 Nov 2012 02:26:55 PST

There is an increasing diversity of educational background of students entering Level 7 and Level 8 programmes in engineering in Irish third level education. Student reasoning about basic electricity concepts often differs from accepted explanations. The paper reports, analyses and reflects on the results of a multiple-choice diagnostic test to assess student understanding of such concepts (developed by Engelhardt and Beichner (2004) for U.S. high school and college students) taken by four cohorts of students, on the same DIT Level 7 engineering programme, from 2008-12 (n=106) and two cohorts of students, on the same DIT Level 8 engineering programme, from 2010-12 (n=64). This paper updates a previous contribution (O’Dwyer, 2009) which described the application of the test to two cohorts of Level 7 students in the 2008-9 academic year.

Comparison of Examination Performance in Mathematics, Physics and Electricity of First Year, Level 7 Student Cohorts in Electrical Engineering

Aidan O'Dwyer — Mon, 11 Jun 2012 09:49:48 PDT

This contribution reports on the highly statistically significant relationship (p < 0.001) established in student examination performance in the three central scientific subjects in a Level 7, Year 1 engineering programme at Dublin Institute of Technology. A range of data is taken over seven academic years (from 2005-12 inclusive). Recommendations for learning and teaching as a result of this analysis are proposed.

A Comparison of Studies Conducted in Wales and Ireland on Issues Affecting Uptake of Micro-Generation Training

Alan E. Harrison et al. — Thu, 15 Mar 2012 07:57:21 PDT

In 2007 Irvine and Stafford [1] surveyed the attitude to the need for enhanced renewable education within groups of Electricians, Architects and Chemists in Wales. Similar groups were surveyed in Ireland in 2008. In comparing the attitudes of students in these two countries the principal differences are governmental support for microgeneration, the quantity of installed microgeneration and the year of the survey. The two countries are broadly similar in terms of geography, climate, population size, ethnicity, broadcast media, educational achievements, economy and income spread.

In Ireland there is greater support for governmental intervention and for increased levels of installation. This could be a reaction to the very low level of activity that prevails in Ireland. The rapid changes during 2008 in economic outlook and in Climate Change consensus may have impacted on the responses. In many areas addressed in the survey the disciplines adopted a consensus position that superseded the national differences.

Observations of the Wind Resource Across the Dublin Urban Area

Keith Sunderland et al. — Wed, 25 Jan 2012 02:25:18 PST

This paper presents an investigation of wind observations made at three (of a network of ten) stations in Dublin. Two of the stations are located over different parts of the urbanized landscape and one is located at Dublin Airport, which exemplifies a typical meteorological station. The purpose of the analysis is to evaluate the nature of the wind resource in the urban area. The potential output of a range of commercially available micro wind turbines at one of the stations is considered. At this location, an anemometer is mounted in a similar manner to international examples of building mounted domestic installations of micro wind turbines. Finally, the paper investigates the relevancy of the Weibull and Rayleigh probability density functions as a means to represent urban wind power density for this Network.

The Role of Micro Wind Generation in Ireland’s Energy Future

Keith Sunderland et al. — Wed, 25 Jan 2012 01:44:25 PST

This paper defines the current position for micro-generation, with particular reference to the potential for micro-wind units, in the Irish electricity supply system. A network model is developed using the Distflow method of load flow analysis and is applied to consider the appropriate level of micro-generation penetration.

The Probabilistic Integration of Demand-Side Load and Generation in a Representative Irish Distribution Network

Keith Sunderland et al. — Wed, 25 Jan 2012 01:36:57 PST

This paper introduces a methodology for investigating the behaviour of a distribution network incorporating both load variations and variable micro-wind generation output. The probabilistic methodology is applied to a representative model of the Irish Distribution Network. Application of a selection of commercially available micro-wind turbines to the model is investigated for a range of load and generation scenarios based on a standard load profile and varying mean wind speed. Analysis of the results of the analysis forms the basis for defining the limitations of the methodology but also presents the opportunities for future work.

Estimating the Yield of Micro Wind Turbines in an Urban Environment: A Methodology

Keith Sunderland et al. — Wed, 25 Jan 2012 01:28:32 PST

Micro wind turbines currently have the majority share of micro (electricity) generation installations in Ireland. These technologies are being installed predominantly in rural environments, and current applications to the Distribution Services Operator (DSO) for connection of all types of micro generator stand at less than 500. Poor market dissemination of information and research findings compounded with poor options for spill payment - as well as onerous planning restrictions do not –it appears - create a platform conducive to encouraging development in this market.

This paper outlines the complexities associated with evaluating the wind resource within an urban environment and investigates the means to ‘estimate’ wind regimes in an urban environment based on an extrapolation of a reference wind speed from a rural environment into the urban area. Methodologies for estimating the wind speed in such circumstances are considered with modeled wind data – benchmarked against wind data acquired from a site in the city centre - being applied to a set of commercially available wind turbines.

On the Applications of Deterministic Chaos for Encrypting Data on the Cloud

Jonathan Blackledge et al. — Fri, 28 Oct 2011 06:10:10 PDT

Cloud computing is expected to grow considerably in the future because it has so many advantages with regard to sale and cost, change management, next generation architectures, choice and agility. However, one of the principal concerns for users of the Cloud is lack of control and above all, data security. This paper considers an approach to encrypting information before it is ‘placed’ on the Cloud where each user has access to their own encryption algorithm, an algorithm that is based on a set of iterated function systems that outputs a chaotic number stream, designed to produce a cryptographically secure cipher. We study cryptographic systems using finite-state approximations to chaos or ‘pseudo-chaos’ and develop an approach based on the concept of multi-algorithmic cryptography that exploits the properties of pseudo-chaos. Although such algorithms can be taken to be in the public domain in order to conform with the Kerchhoff-Shannon principal, i.e. the enemy knows the system, their combination can be used to secure data in a way that is unique to each user. This provides the potential for users of the Cloud to upload and transfer data in the knowledge that they are encrypting their data in a way that is algorithm as well key dependent, thereby defeating a known algorithm attack. This paper reports on one application of this approach called Crypstic in which the encryption engine is mounted on a USB memory stick and where the key is automatically generated by the characteristics of the plaintext/ciphertext file.