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Subject = Applied Statistics;
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Displaying Results 1 - 15 of 15 on page 1 of 1
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A Stochastic Model for Wind Turbine Power Quality using a Levy Index Analysis of Wind Velocity Data
(2011)
Blackledge, Jonathan; Coyle, Eugene; Kearney, Derek
A Stochastic Model for Wind Turbine Power Quality using a Levy Index Analysis of Wind Velocity Data
(2011)
Blackledge, Jonathan; Coyle, Eugene; Kearney, Derek
Abstract:
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. After a brief review of the statistics of typical wind speed data, a non- Gaussian model for the wind velocity is introduced that is based on a Levy distribution. It is shown how this distribution can be used to derive a stochastic fractional diusion equation for the wind velocity as a function of time whose solution is characterised by the Levy index. A Levy index numerical analysis is then performed on wind velocity data for both rural and urban areas where, in the latter case, the index has a larger value. Finally, an empirical relationship is derived for the power output from a wind turbine in terms of the Levy index using Betz law.
https://arrow.dit.ie/engscheleart/146
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An Examination of the Neural Unreliability Thesis of Autism
(2016)
Butler, John; Molholm, Sophie; Andrade, Gizely; Foxe, John J
An Examination of the Neural Unreliability Thesis of Autism
(2016)
Butler, John; Molholm, Sophie; Andrade, Gizely; Foxe, John J
Abstract:
An emerging neuropathological theory of Autism, referred to here as “the neural unreliability thesis,” proposes greater variability in moment-to-moment cortical representation of environmental events, such that the system shows general instability in its impulse response function. Leading evidence for this thesis derives from functional neuroimaging, a methodology ill-suited for detailed assessment of sensory transmission dynamics occurring at the millisecond scale. Electrophysiological assessments of this thesis, however, are sparse and unconvincing. We conducted detailed examination of visual and somatosensory evoked activity using high-density electrical mapping in individuals with autism (N = 20) and precisely matched neurotypical controls (N = 20), recording large numbers of trials that allowed for exhaustive timefrequency analyses at the single-trial level. Measures of intertrial coherence and event-related spectral perturbation revealed no convincing evidence for an unreliabi...
https://arrow.dit.ie/scschmatart/223
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Analysing Domestic Electricity Smart Metering Data Using Self Organising Maps
(2012)
McLoughlin, Fintan; Duffy, Aidan; Conlon, Michael
Analysing Domestic Electricity Smart Metering Data Using Self Organising Maps
(2012)
McLoughlin, Fintan; Duffy, Aidan; Conlon, Michael
Abstract:
This paper investigates a method of classifying domestic electricity load profiles through Self Organising Maps (SOMs). Approximately four thousand customers are divided into groups based on their electricity demand patterns. Dwelling and occupant characteristics are then investigated for each group. The results show that SOMs are an effective way of classifying customers into groups in terms of their electrical load profile and that certain dwelling and occupant characteristics are significant factors in determining which group they end up in.
https://arrow.dit.ie/dubencon2/68
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Application of the Fractional Diffusion Equation for Predicting Market Behaviour
(2010)
Blackledge, Jonathan
Application of the Fractional Diffusion Equation for Predicting Market Behaviour
(2010)
Blackledge, Jonathan
Abstract:
Most Financial modelling system rely on an underlying hypothesis known as the Eficient Market Hypothesi (EMH) including the famous BlackScholes formula for placing an option. However, the EMH has a fundamental flaw: it is based on the assumption that economic processes are normally distributed and it has long been known that this is not the case. This fundamental assumption leads to a number of shortcomings associated with using the EMH to analyse financial data which includes failure to predict the future volatility of a market share value. This paper introduces a new financial risk assessment model based on Levy statistics and considers a financial forecasting system that uses a solution to a non-stationary fractional diusion equation characterized by the Levy index. Variation in the Levy index are considered in order to assess the future volatility of financial data together with the likelihood of the markets become bear or bull dominant thereby providing a solution to securing a...
https://arrow.dit.ie/engscheleart2/11
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Best practices for use of stable isotope mixing models in food web studies
(2014)
Jackson, Andrew
Best practices for use of stable isotope mixing models in food web studies
(2014)
Jackson, Andrew
Abstract:
Stable isotope mixing models are increasingly used to quantify consumer diets, but may be misused and misinterpreted. We address major challenges to their effective application. Mixing models have increased rapidly in sophistication. Current models estimate probability distributions of source contributions, have user friendly interfaces, and incorporate complexities such as variability in isotope signatures, discrimination factors, hierarchical variance structure, covariates, and concentration4dependence. For proper implementation of mixing models, we offer the following suggestions. First, mixing models can only be as good as the study and data. Studies should have clear questions, be informed by knowledge of the system, and have strong sampling designs to effectively characterize isotope variability of consumers and resources on proper spatio4temporal scales. Second, studies should use models appropriate for the question and recognize their assumptions and limitations. Decisions a...
http://hdl.handle.net/2262/71218
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Economic Risk Assessment using the Fractal Market Hypothesis
(2010)
Blackledge, Jonathan; Rebow, Marek
Economic Risk Assessment using the Fractal Market Hypothesis
(2010)
Blackledge, Jonathan; Rebow, Marek
Abstract:
This paper considers the Fractal Market Hypothesi (FMH) for assessing the risk(s) in developing a financial portfolio based on data that is available through the Internet from an increasing number of sources. Most financial risk management systems are still based on the Efficient Market Hypothesis which often fails due to the inaccuracies of the statistical models that underpin the hypothesis, in particular, that financial data are based on stationary Gaussian processes. The FMH considered in this paper assumes that financial data are non-stationary and statistically self-affine so that a risk analysis can, in principal, be applied at any time scale provided there is sufficient data to make the output of a FMH analysis statistically significant.
https://arrow.dit.ie/engscheleart/151
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Embodied Emissions Abatement: a Policy Assessment using Stochastic Analysis
(2011)
Duffy, Aidan; Acquaye, Adolf; Basu, Biswajit
Embodied Emissions Abatement: a Policy Assessment using Stochastic Analysis
(2011)
Duffy, Aidan; Acquaye, Adolf; Basu, Biswajit
Abstract:
Policymakers traditionally focus on regulating operational energy use in buildings, ignoring other life cycle components such as embodied energy even though this may account for a significant portion of life cycle emissions. Data relating to embodied energy and emissions in buildings is limited. However, stochastic techniques can be used to estimate the distribution of such emissions from buildings. This helps policymakers identify which instruments are appropriate for achieving emissions reductions. A primary aim of this paper is to demonstrate this approach using a sample of apartment buildings in Ireland. A Monte-Carlo simulation suggests that the average probability distribution of embodied greenhouse gases in a sample of Irish apartment buildings is characteristic of a Wakeby distribution with a long tail which can be targeted for improvement through the implementation of appropriate policies. Two policies are investigated: one regulatory whereby the embodied emissions of build...
https://arrow.dit.ie/engschcivart/13
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Encryption using Deterministic Chaos
(2010)
Blackledge, Jonathan; Ptitsyn, Nikolai
Encryption using Deterministic Chaos
(2010)
Blackledge, Jonathan; Ptitsyn, Nikolai
Abstract:
The concepts of randomness, unpredictability, complexity and entropy form the basis of modern cryptography and a cryptosystem can be interpreted as the design of a key-dependent bijective transformation that is unpredictable to an observer for a given computational resource. For any cryptosystem, including a Pseudo-Random Number Generator (PRNG), encryption algorithm or a key exchange scheme, for example, a cryptanalyst has access to the time series of a dynamic system and knows the PRNG function (the algorithm that is assumed to be based on some iterative process) which is taken to be in the public domain by virtue of the Kerchhoff-Shannon principal, i.e. the enemy knows the system. However, the time series is not a compact subset of a trajectory (intermediate states are hidden) and the iteration function is taken to include a ‘secret parameter’ - the ‘key’. We can think of the sample as being ‘random’, ‘unpredictable’ and ‘complex’. What do these properties mean mathematically and...
https://arrow.dit.ie/engscheleart2/15
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Exponential family mixed membership models for soft?clustering of multivariate data
(2016)
White, Arthur
Exponential family mixed membership models for soft?clustering of multivariate data
(2016)
White, Arthur
Abstract:
For several years, model-based clustering methods have successfully tackled many of the challenges presented by data-analysts. However, as the scope of data analysis has evolved, some problems may be beyond the standard mixture model framework. One such problem is when observations in a dataset come from overlapping clusters, whereby different clusters will possess similar parameters for multiple variables. In this setting, mixed membership models, a soft clustering approach whereby observations are not restricted to single cluster membership, have proved to be an effective tool. In this paper, a method for fitting mixed membership models to data generated by a member of an exponential family is outlined. The method is applied to count data obtained from an ultra running competition, and compared with a standard mixture model approach.
http://hdl.handle.net/2262/76841
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Multi-algorithmic Cryptography using Deterministic Chaos with Applications to Mobile Communications
(2008)
Blackledge, Jonathan
Multi-algorithmic Cryptography using Deterministic Chaos with Applications to Mobile Communications
(2008)
Blackledge, Jonathan
Abstract:
In this extended paper, we present an overview of the principal issues associated with cryptography, providing historically significant examples for illustrative purposes as part of a short tutorial for readers that are not familiar with the subject matter. This is used to introduce the role that nonlinear dynamics and chaos play in the design of encryption engines which utilize different types of Iteration Function Systems (IFS). The design of such encryption engines requires that they conform to the principles associated with diffusion and confusion for generating ciphers that are of a maximum entropy type. For this reason, the role of confusion and diffusion in cryptography is discussed giving a design guide to the construction of ciphers that are based on the use of IFS. We then present the background and operating framework associated with a new product - CrypsticTM - which is based on the application of multi-algorithmic IFS to design encryption engines mounted on a USB memory...
https://arrow.dit.ie/engscheleart2/29
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Rate of familial amyotrophic lateral sclerosis: a systematic review and meta-analysis.
(2011)
WALSH, CATHAL; BEDE, PETER; HARDIMAN, ORLA; MCLAUGHLIN, RUSSELL; WALTON, CLAIR
Rate of familial amyotrophic lateral sclerosis: a systematic review and meta-analysis.
(2011)
WALSH, CATHAL; BEDE, PETER; HARDIMAN, ORLA; MCLAUGHLIN, RUSSELL; WALTON, CLAIR
Abstract:
Background The population rate of familial amyotrophic lateral sclerosis (FALS) is frequently reported as 10%. However, a systematic review and meta-analysis of the true population based frequency of FALS has never been performed. Method A Medline literature review identified all original articles reporting a rate of FALS. Studies were grouped according to the type of data presented and examined for sources of case ascertainment. A systematic review and meta-analysis of reported rates of FALS was then conducted to facilitate comparison between studies and calculate a pooled rate of FALS. Results 38 papers reported a rate of FALS. Thirty-three papers were included in analysis and the rate of FALS for all studies was 4.6% (95% CI 3.9% to 5.5%). Restricting the analysis to prospective population based registry data revealed a rate of 5.1% (95% CI 4.1% to 6.1%). The incidence of FALS was lower in southern Europe. There was no correlation between rate of FALS and reported SOD1 mutation r...
http://hdl.handle.net/2262/53330
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Stochastic Hybrid Embodied CO2-eq Analysis: an Application to the Irish Apartment Building Sector
(2011)
Acquaye, Adolf; Duffy, Aidan; Basu, Biswajit
Stochastic Hybrid Embodied CO2-eq Analysis: an Application to the Irish Apartment Building Sector
(2011)
Acquaye, Adolf; Duffy, Aidan; Basu, Biswajit
Abstract:
Although embodiedCO2-eq analysis has seen recent developments as evident in the establishment of the ISO14040 and 14044 LCA standards, it is recognized that due to weaknesses in gathering data on product-related emissions,embodiedCO2-eq values are probabilistic. This paper presents a stochastic analysis of hybrid embodied CO2-eq in buildings to account for this weakness in traditional methods and, by way of example, applies it to an Irish construction-sector case study. Using seven apartment buildings, 70,000 results are simulated with Monte Carlo analysis and used to derive probabilistic and cumulative embodied CO2-eq intensity distributions for apartment buildings in Ireland. A Wakeby distribution with known statistical parameters and uncertainty was derived for the average embodied CO2-eq intensity of apartment building in Ireland. The mean hybrid embodied CO2-eq (ECO2-eq) intensity was estimated to be 1,636gCO2-eq/€ with an uncertainty of 73gCO2-eq/€ . The stochastic analysis he...
https://arrow.dit.ie/dubenart/46
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The effects of Flare Definitions on the Statistics of Derived Flare Distributions.
(2016)
WHITE, ARTHUR
The effects of Flare Definitions on the Statistics of Derived Flare Distributions.
(2016)
WHITE, ARTHUR
Abstract:
The statistical examination of solar flares is crucial to revealing their global characteristics and behaviour. Such examinations can tackle large-scale science questions or give context to detailed single-event studies. However, they are often performed using standard but basic flare detection algorithms relying on arbitrary thresholds. This arbitrariness may lead to important scientific conclusions being drawn from results caused by subjective choices in algorithms rather than the true nature of the Sun. In this paper, we explore the effect of the arbitrary thresholds used in the GOES (Geostationary Operational Environmental Satellite) event list and LYRA (Large Yield RAdiometer) Flare Finder algorithms. We find that there is a small but significant relationship between the power law exponent of the GOES flare peak flux frequency distribution and the flare start thresholds of the algorithms. We also find that the power law exponents of these distributions are not stable, but appea...
http://hdl.handle.net/2262/76840
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The Generation of Domestic Electricity Load Profiles through Markov Chain Modelling
(2010)
Duffy, Aidan; McLoughlin, Fintan; Conlon, Michael
The Generation of Domestic Electricity Load Profiles through Markov Chain Modelling
(2010)
Duffy, Aidan; McLoughlin, Fintan; Conlon, Michael
Abstract:
Micro-generation technologies such as photovoltaics and micro-wind power are becoming increasing popular among homeowners, mainly a result of policy support mechanisms helping to improve cost competiveness as compared to traditional fossil fuel generation. National government strategies to reduce electricity demand generated from fossil fuels and to meet European Union 20/20 targets is driving this change. However, the real performance of these technologies in a domestic setting is not often known as high time resolution models for domestic electricity load profiles are not readily available. As a result, projections in terms of reducing electricity demand and financial paybacks for these micro-generation technologies are not always realistic. Domestic electricity load profiles are often highly stochastic, influenced by many different independent variables such as environmental, dwelling and occupant characteristics that shape individual customer’s load across a single day. This pap...
https://arrow.dit.ie/dubencon2/9
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The Importance of Inhaler Technique in Measuring and Calculating Inhaler Adherence, and its Clinical Outcomes
(2017)
Sulaiman, Imran
The Importance of Inhaler Technique in Measuring and Calculating Inhaler Adherence, and its Clinical Outcomes
(2017)
Sulaiman, Imran
Abstract:
<p>Depending on the population studied, cross-sectional observational studies suggest that between 14%-90% of patients do not use their pressurized metered dose inhaler correctly, while 50-60% misuse a dry powder inhaler. This means that unless incorrect technique is acounted for a significant underestimation of how much medication the person actually obtained may be made.</p> <p>The aim of this thesis was to objectively determine the frequency and importance of inhaler technique errors and to combine these with inhaler use to provide an acurate method of calculating adherence. I then investigated different patterns of inhaler use, determinants of inhaler use and the impact of education directed at technique of inhaler use has on adherence and clinical outcomes.</p> <p>To assess inhaler adherence the INhaler Compliance Assessment (INCATM) device was used. This device records digital audio of a patient using their inhaler to provide information on time a...
https://epubs.rcsi.ie/phdtheses/191
Displaying Results 1 - 15 of 15 on page 1 of 1
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Institution
Dublin Institute of Technology (10)
Royal College of Surgeons i... (1)
Trinity College Dublin (4)
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