Physical Sciences and Mathematics Commons^™

Combining Outputs From The North American Regional Climate Change Assessment Program By Using A Bayesian Hierarchical Model, Emily L. Kang, Noel Cressie, Stephan R. Sain

Faculty of Informatics - Papers (Archive)

We investigate the 20-year-average boreal winter temperatures generated by an ensemble of six regional climate models (RCMs) in phase I of the North American Regional Climate Change Assessment Program. We use the long-run average (20-year integration) to smooth out variability and to capture the climate properties from the RCM outputs. We find that, although the RCMs capture the large-scale climate variation from coast to coast and from south to north similarly, their outputs can differ substantially in some regions. We propose a Bayesian hierarchical model to synthesize information from the ensemble of RCMs, and we construct a consensus climate signal …

Theory Of Gaussian Variational Approximation For A Poisson Mixed Model, Peter Hall, J T. Ormerod, M P. Wand

Faculty of Informatics - Papers (Archive)

Likelihood-based inference for the parameters of generalized linear mixed models is hindered by the presence of intractable integrals. Gaussian variational approximation provides a fast and effective means of approximate inference. We provide some theory for this type of approximation for a simple Poisson mixed model. In particular, we establish consistency at rate m^−1/2 +n⁻¹, where m is the number of groups and n is the number of repeated measurements.

Statistical Analysis Model Predicting Computer Use In Mathematics, Rebecca Hudson, Anne Porter, Mark Nelson

Faculty of Informatics - Papers (Archive)

This paper is a report of a doctoral thesis that investigated the factors that were associated with the use of computers in secondary mathematics teaching, the choices made by teachers and learning theories guiding their teaching. Mixed methods approaches were used to triangulate the results of the study. The study was divided into three stages, the first a questionnaire completed by 114 teachers, the second was examination of current accredited courses in teacher preparation for mathematics teaching to identify what learning theories were included in subjects, and the third were interviews with 8 teachers in training and 6 experienced teachers. …

Asymptotic And Numerical Results For A Model Of Solvent-Dependent Drug Diffusion Through Polymeric Spheres, Scott Mccue, Mike Hsieh, Timothy J. Moroney, Mark I. Nelson

Faculty of Informatics - Papers (Archive)

A model for drug diffusion from a spherical polymeric drug delivery device is considered. The model contains two key features. The first is that solvent diffuses into the polymer, which then transitions from a glassy to a rubbery state. The interface between the two states of polymer is modeled as a moving boundary, whose speed is governed by a kinetic law; the same moving boundary problem arises in the one-phase limit of a Stefan problem with kinetic undercooling. The second feature is that drug diffuses only through the rubbery region, with a nonlinear diffusion coefficient that depends on the concentration …

A Mathematical Model For The Biological Treatment Of Industrial Wastewaters In A Cascade Of Four Reactors, Annette L. Worthy, Mark I. Nelson, Rubayyi Turki Alqahtani

Faculty of Informatics - Papers (Archive)

Many industrial processes, particularly in the food industry, produce slurriesor wastewaters containing high concentrations of biodegradable organicmaterials. Before these contaminated wastewaters can be dischargedthe concentration of these pollutants must be reduced. A method which has beenextensively employed to remove biodegradable organic matter is biologicaltreatment. In this process the wastewater (or slurry) is passed through abioreactor containing biomass which grows through consumption of thepollutants.The industrial treatment of wastewaters typically employs a reactor cascade.In a reactor cascade of n reactors the effluent stream from the ith reactor inthe cascade acts as the feed stream for the (i+1)th reactor, i.e. the nextreactor. The …

A Preliminary Investigation Of Complex Adaptive Systems As A Model For Explaining Organisational Change Caused By The Introduction Of Health Information Systems, Kieren Diment, Ping Yu, Karin Garrety

Faculty of Informatics - Papers (Archive)

This paper documents the preliminary development of a framework for evaluating organisational change processes during the implementation of an electronic nursing documentation system in residential aged care facilities. It starts with a brief outline of organisational change processes. This is followed by a more detailed exposition of the principles underlying complex adaptive systems (CAS) theory, where we explain how mathematical concepts can be used to illuminate qualitative research approaches. Finally we present some preliminary findings on the facilitators and barriers for the introduction of the electronic documentation system, explained with reference to the CAS theory, based on analysis of interviews …

An Assessment Tool For E-Government System Performance: A Citizen-Centric Model, Shatha A. Al-Haddad, Peter Hyland, Geoffrey Hubona

Faculty of Informatics - Papers (Archive)

Governments worldwide have, increasingly, implemented e-government initiatives for their potential significant benefits; among which, delivering better services to citizens through increasing citizens' convenience, satisfaction, and independence; and saving their time, effort, and cost. Achieving each benefit is an objective to these governments and fulfilling each objective is considered a critical success factors. Hence, governments need to assess the extent to which they were able to obtain their preset goals. This study merely focuses on the citizens' perspective of the evaluation. However, the literature seems to lack studies that propose such a sufficient evaluation tool that has been reliably validated. Therefore, …

Using Singularity Theory To Analyse A Spatially Uniform Model Of Self-Heating In Compost Piles, Thiansiri Luangwilai, Harvinder Sidhu, Mark Nelson, Xiao Dong Chen

Faculty of Informatics - Papers (Archive)

Fires at industrial composting facilities, such as those storing industrial waste products like municipal solid waste (NSW) and landfills are fairly common. In most cases these are manageable and such incidents are not destructive enough to attract attention beyond these facilities. However, over the years there have been a few notable devastating fires at such facilities.

In each of these industrial processes there is an inherent increase in temperature as a consequence of the biological activity. Indeed such a temperature increase is one of the goals of the composting waste. Elevated temperatures of the order of 70-90 degrees celsius have …

Pbtrust: A Priority-Based Trust Model For Service Selection In General Service-Oriented Environments, Xing Su, Minjie Zhang, Yi Mu, Kwang Mong Sim

Faculty of Informatics - Papers (Archive)

How to choose the best service provider (agent), which a service consumer can trust in terms of the quality and success rate of the service in an open and dynamic environment, is a challenging problem in many service-oriented applications such as Internet-based grid systems, e-trading systems, as well as service-oriented computing systems. This paper presents a Priority-Based Trust (PBTrust) model for service selection in general service-oriented environments. The PBTrust is robust and novel from several perspectives. (1) The reputation of a service provider is derived from referees who are third parties and had interactions with the provider in a rich …

Dynamic Trust Model For Federated Identity Management, Hao Gao, Jun Yan, Yi Mu

Faculty of Informatics - Papers (Archive)

The goal of federated identity management is to allow principals, such as identities and attributes, to be shared across trust boundaries based on established policies. Since current Single Sign-On (SSO) mechanism excessively relies on the specifications of Circle of Trust (CoT), the need for service collaboration from different domains is being addressed on CoT. For the motivating issue of the cross-domain SSO mechanism, we need an emergent dynamic trust list for calculating the trust parties, thus, the CoT specifications require an initial effort on enrolling members automatically to adapt to the dynamic open environment. In this paper, we propose a …

Estimation In A Multiplicative Mixed Model Involving A Genetic Relationship Matrix, Alison M. Kelly, Brian R. Cullis, Arthur R. Gilmour, John A. Eccleston, Robin Thompson

Faculty of Informatics - Papers (Archive)

Genetic models partitioning additive and non-additive genetic effects for populations tested in replicated multi-environment trials (METs) in a plant breeding program have recently been presented in the literature. For these data, the variance model involves the direct product of a large numerator relationship matrix A, and a complex structure for the genotype by environment interaction effects, generally of a factor analytic (FA) form. With MET data, we expect a high correlation in genotype rankings between environments, leading to non-positive definite covariance matrices. Estimation methods for reduced rank models have been derived for the FA formulation with independent genotypes, and we …

Hierarchical Model Building, Fitting, And Checking: A Behind-The-Scenes Look At A Bayesian Analysis Of Arsenic Exposure Pathways, Peter F. Craigmile, Catherine A. Calder, Hongfei Li, Rajib Paul, Noel Cressie

Faculty of Informatics - Papers (Archive)

In this article, we present a behind-the-scenes look at a Bayesian hierarchical analysis of pathways of exposure to arsenic (a toxic heavy metal) using the Phase I National Human Exposure Assessment Survey carried out in Arizona. Our analysis combines individual-level personal exposure measurements (biomarker and environmental media) with water, soil, and air observations from the ambient environment. We include details of our model-building exercise that involved a combination of exploratory data analysis and substantive knowledge in exposure science. Then we present our strategies for model fitting, which involved piecing together components of the hierarchical model in a systematic fashion to …

Generalised Linear Mixed Model Analysis Via Sequential Monte Carlo Sampling, Y Fan, D S. Leslie, M P. Wand

Faculty of Informatics - Papers (Archive)

We present a sequential Monte Carlo sampler algorithm for the Bayesian analysis of generalised linear mixed models (GLMMs). These models support a variety of interesting regression-type analyses, but performing inference is often extremely difficult, even when using the Bayesian approach combined with Markov chain Monte Carlo (MCMC). The Sequential Monte Carlo sampler (SMC) is a new and general method for producing samples from posterior distributions. In this article we demonstrate use of the SMC method for performing inference for GLMMs. We demonstrate the effectiveness of the method on both simulated and real data, and find that sequential Monte Carlo is …

Implementation Of Artificial Intelligence Technique To Model Arc Furnace Responses, A.M.O Haruni, Michael Negnevitsky, M.E Haque, Kashem Muttaqi

Faculty of Informatics - Papers (Archive)

Random variations of the bus voltage and power consumption of an electric arc furnace (EAF) have a significant impact on power generation equipment, transient stability of the power system network and power quality to other interconnected loads. Therefore, an accurate representation of the load's dynamic behaviour under various system disturbances is very important. This paper presents an arc furnace model using adaptive neuro-fuzzy inference system (ANFIS) in order to capture random, non-linear and time-varying load pattern of an arc furnace. To evaluate the performance of the proposed model, several case studies are presented where the outputs of the proposed model …

Autoignition Of Hydrocarbons In A Batch Reactor: Analysis Of A Reduced Model, Mark I. Nelson, E Balakrishnan

Faculty of Informatics - Papers (Archive)

n the late 1960s Gray and Yang developed the first reduced kinetic model for the oxidation of hydrocarbon fuels that qualitatively described many features observed experimentally. Since then a number of reduced kinetic models have been proposed in the literature. In this contribution we analyse the steady-state behaviour of one such scheme. The chemical component of the model contains four chemical species undergoing six reactions. By making a pool-chemical approximation this system is reduced to three coupled non-linear differential equations: a temperature equation and equations for two reactive chemical intermediates. It is shown that any steady-state solution of this model …

A Numerical Model For Multiphase Flow Based On The Gmpps Formulation, Part I Kinematics, Song-Ping Zhu, Frank Bierbrauer

Faculty of Informatics - Papers (Archive)

The CFD modeling of two dimensional multiphase ows is a useful tool in industry, although accurate modeling itself remains a difficult task. One of the difficulties is to track the complicated topological deformations of the interfaces between di erent phases. This paper describes a marker-particle method designed to track fluid interfaces for fluid ows of at least three phases. The interface-tracking scheme presented in this paper is the first part of a series of papers presenting our complete model based on a one-field Godunov marker-particle projection scheme (GMPPS). In this part, we shall focus on the presentation of the interface-tracking …

Application Of Semistructured Data Model To The Implementation Of Semantic Content-Based Video Retrieval System, Lilac A. E. Al-Safadi, Janusz R. Getta

Faculty of Informatics - Papers (Archive)

Semantic indexing of a video document is a process that performs the identification of elementary and complex semantic units in the indexed document in order to create a semantic index defined as a mapping of semantic units into the sequences of video frames. Semantic content-based video retrieval system is a software system that uses a semantic index built over a collection of video documents to retrieve the sequences of video frames that satisfy the given conditions. This work introduces a new multilevel view of data for the semantic content-based video retrieval systems. At the topmost level, we define an abstract …

Analysis Of A Model For The Treatment Of Wastewater By The Activated Sludge Process, Simon D. Watt, Harvinder S. Sidhu, Mark I. Nelson

Faculty of Informatics - Papers (Archive)

We investigate a model for the treatment of wastewater in the activated sludge process. This process is based on the aeration of waste water with flocculating biological growth, followed by the separation of treated waste water from biological growth. Part of this growth is then wasted, and the remainder is returned to the system. The wastewater reactor is assumed to be well mixed, so the mathematical formulation for this process can be represented by a continuously stirred tank reactor with recycle. This system is analysed by combining steady-state analysis with path-following techniques. In practice, wastewater is treated by a sequence …

The Analysis Of Crop Cultivar Breeding And Evaluation Trials: An Overview Of Current Mixed Model Approaches, A B. Smith, Brian R. Cullis, R Thompson

Faculty of Informatics - Papers (Archive)

The analysis of series of crop variety trials has a long history with the earliest approaches being based on ANOVA methods. Kempton (1984) discussed the inadequacies of this approach, summarized the alternatives available at that time and noted that all of these approaches could be classified as multiplicative models. Recently, mixed model approaches have become popular for the analysis of series of variety trials. There are numerous reasons for their use, including the ease with which incomplete data (not all varieties in all trials) can be handled and the ability to appropriately model within-trial error variation. Currently, the most common …

Nonlinear Sigma Model For Odd-Frequency Triplet Superconductivity In Superconductor/Ferromagnet Structures, J E. Bunder, K B. Efetov

Faculty of Informatics - Papers (Archive)

No abstract provided.