106 results for Conference paper, ResearchSpace@Auckland

  • Flow-based resource allocation in a multiple-access wireless market-setting using an auction

    Roggendorf, Matthias; Beltran, Fernando (2006)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. This paper presents a flow-based, auction-driven approach to resource allocation. This approach allows mobile stations to simultaneously negotiate for resources from competing providers. We use an auction at each provider to decide on the resource allocation, based on the offers made by agents representing mobile nodes. All agents in the system try to maximise their utility gained from the total allocation of resources. The focus of this paper is on the bidding strategy of a mobile station when faced with the opportunity to obtain network resources from multiple sources. We support the proposed bidding strategy by simulation experiments, which show that the resulting allocation is efficient under the limited scope of the simulation setup.We also show that multiple-access can increase the allocation efficiency compared to the situation in which agents have access to only one network.

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  • A Paradigmatic and Methodological Examination of KM Research: 2000 to 2004

    Zining, Guo; Sheffield, Jim (2006)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. This study addresses a long-standing and well-recognized problem in KM research, namely the lack of a cumulative tradition. This problem is addressed by an intensive and critical review of the knowledge management literature that identifies gaps and recommends how these should be filled. KM articles are classified by research paradigm, research methodology, and research interest (technical, practical, and emancipatory). The survey methodology is intensive. Leading journals that publish significant knowledge management research are identified. All articles relevant to knowledge management, organizational learning, and organizational memory for the five-year period 2000-2004 are surveyed and classified by multiple reviewers. The key finding is that inquiry in KM is starkly unbalanced. Overuse of the positivist paradigm and its dominant research method (sample survey) prevents the exploitation of the highly relevant insights available via the use of the interpretivist and critical pluralist paradigms and the field study method.

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  • Design of heterogeneous embedded systems using DFCharts model of computation

    Radojevic, Ivan; Salcic, Zoran; Roop, Partha (2006)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Dataflow process networks have been successfully used for modeling signal processing systems which are data-dominated. In this family of models, the most popular one is synchronous dataflow (SDF). On the other hand, hierarchical concurrent finite state machines (HCFSM) have been successfully employed for control-dominated systems. Most complex embedded systems are heterogeneous, consisting of both control-dominated and data-dominated parts. In this paper, we introduce a new model of computation, called DFCharts, which targets heterogeneous embedded systems. It combines the HCFSM (with Argos semantics) and SDF models. It has a formal, operational semantics based on Boolean automata with variables.

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  • Numerical Simulation of Electrolyte Two-Phase Flow Induced by Anode Bubbles in an Aluminum Reduction Cell

    Zhou, Naijun; Xue, Yuqing; Chen , John; Taylor, Mark (2007)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. In the production process of aluminium reduction cells, the anode bubble laden layer has several important influences on the performance of the aluminium reduction cells. Especially for a “drained cathode cell”, without the agitating of movement of the melted metal, the bath flow field could be more important. In this paper, the electrolyte two-phase flow fields were studied by using numerically simulation method based on a two-phase turbulence model combining the k - model and the Discrete Random Walk model. The results show that: the motion of the bubbles mostly exists within a thin layer under the anode, which results in inducing local electrolyte to flow around the anode in various circulation flows; the flow field in the anode-cathode space can be divided into three regions with different characters; the results also show the Driving action of bubbles is closely related to the current density, inclination of anode and the anode-cathode distance. In general, the increasing in the current density increases the electrolyte velocity and the turbulent kinetic energy. The decrease in ACD significantly enhances the uniformity of the electrolyte flow field in the anode-cathode space. The increase in anode inclination angle increases the velocity of the electrolyte in the anode-cathode space, which would be beneficial to improving the diffusion and dissolution of the alumina and reducing the resistance between the anode and cathode.

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  • The thermo-hydrodynamics of a concentric ohmic heater for processing dairy fluids.

    Tham, H.J.; Chen, X.D.; Young, B.; Zhang, L.; Duffy, G. (2007)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. The thermo-hydraulic performance of a 300W concentric annular ohmic heater was investigated. To minimize possible electrochemical reactions and corrosion, a higher frequency was applied and factors of field strength and frequency were studied. 2D computer simulation solving momentum, thermal and electrical energy was performed using the FlexPDE software. A good agreement between experimental and analytical analysis of static heating was obtained. There were significant differences between calculated and measured wall temperature near the entrance. The calculated outlet temperature was however in reasonable agreement with the experiment value.

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  • Dirty Work

    McMeel, Dermott; Coyne, Richard (2005)

    Conference paper
    The University of Auckland Library

    Conference Details: Proc. W1 18th British HCI Group Annual Conference 6-10 September – Designer, User, Meaning Maker: Rethinking Relationships for a More Creative HCI. pp. 26-29. Leeds: Leeds Metropolitan University. This research explores the potency of dirt as a category for understanding digital communications. Our eventual target domain is communication in the construction industry, which is characterised by contractual formalities on the one hand (working documents, specifications, forms), and informal communications on the other (onsite instructions, scribbles on paper). Electronic communications (such as email and message boards) represent hybrid formal-informal media in the increasingly litigious workplace. On the way to understanding the untidiness of the construction site, we analysed the use of formal and informal communications in group working by students in the design and construction of an interactive digital art installation. Our research so far draws on the interesting relationship between dirt, authority, and human-computer interaction.

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  • Talking Dirty

    McMeel, Dermott; Coyne, Richard; Lee, John (2005)

    Conference paper
    The University of Auckland Library

    We analyse the emergence and use of formal and informal communication tools in group working to aid in understanding the complexity of construction projects. Our test case is the design and build of an interactive digital installation in an exhibition space, involving students. After the project we conducted focus group studies to elicit insights into the effective use of the digital communications available for the project. We recount key insights from the study and examine how digital messaging devices are contributing to or hindering creative discussion. Whereas the construction process is concerned with the removal of dirt and re-ordering, in this paper we reflect on construction’s ritualistic, contractual and unauthorized aspects, and dirt’s role within them. We draw on Bakhtin’s theories of the carnival in exploring ritual, and the mixing of the un-sanctioned (rumour) with the official (contractual). How does dirt impinge on issues of communication, open discussion, and the move towards “partnering” in construction practice? We conjecture that while physical dirt might be unpleasant, the removal of other forms of metaphorical dirt hampers construction as an efficient and creative process.

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  • Speech Enhancement by Multi-Channel Crosstalk Resistant Adaptive Noise Cancellation

    Zeng, Qingning; Abdulla, Waleed (2006)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. A novel Multi-channel Crosstalk Resistant Adaptive Noise Cancellation (MCRANC) algorithm is presented in this paper to enhance noise carrying speech signals. The algorithm would permit locating the microphones in close proximity as it cancels out the crosstalk effect. Results have indicated that this method outperforms the commonly used techniques in the sense of SNR improvement and speech intelligibility. A SNR improvement of 17.8dB using MCRANC keeping highly intelligible speech was achieved in our experiments versus 9.1dB using Multi-channel ANC (MANC) with far less speech quality.

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  • A Variable Inductor Based Tuning Method for ICPT Pickups

    James, Jason; Boys, John T.; Covic, Grant (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. A practical dynamic inductor-tuning circuit for a parallel resonant ICPT power pickup operating at 38.4kHz is described. The method controls the current through a tuning inductor by varying the turn on delay of two power switches. This varies the inductor current so that the tank may be maintained at resonance. Supporting mathematical analysis, circuit simulation and prototype measurements are included. Experimental results have verified the system behaviour.

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  • A soft decision output convolutional decoder based on the application of neural networks

    Berber, Stevan (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. The paper investigates BER characteristics of a new algorithm for decoding convolutional codes based on neural networks. The novelty of the algorithm is in its capability to generate soft output estimates of the message bits encoded. It is shown that the defined noise energy function, which is traditionally used for the soft decoding algorithm of convolutional codes, can be related to the well known log likelihood function. The coding gain is calculated using a developed simulator of a coding communication system that uses a systematic 1/2-rate convolutional code.

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  • E-books - essentials or extras? The University of Auckland Library experience

    Mincic-Obradovic, Ksenija (2004)

    Conference paper
    The University of Auckland Library

    The e-publishing industry is developing rapidly, providing new opportunities for libraries, but creating new challenges as well. Questions on how best to integrate e-books into the learning environment are pressing. In 2003, the University of Auckland Library provided access to nearly 80,000 e-books through the library catalogue only. This paper will explore some of the theoretical and practical issues of implementing e-books in the University of Auckland Library, covering such issues as: - Integration - Workflow - Differences in perception/acceptance of digital texts - Response from students and staff - User preferences and reasons for these

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  • Intrepid traveller: the University of Auckland Library on the e-book journey

    Mincic-Obradovic, Ksenija (2006)

    Conference paper
    The University of Auckland Library

    E-books continue to thrive with e-book technology companies developing a variety of solutions for libraries, many of which offer excellent support for teaching and learning. The objective of this paper is to present the University of Auckland Library’s experiences in integrating e-books into the learning environment. This is a complex issue and will be considered from different perspectives: selection, purchasing, providing access, cataloguing, and user support and satisfaction.

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  • Statistical modeling of speech feature vector trajectories based on a piecewise continuous mean path

    Thomson, Mark M. (1995)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. One of the key tasks in speech recognition based on statistical methods is the calculation of the class conditional probability density. This paper presents a new statistical model of the trajectories of speech feature vectors. In this model each vector is assumed to correspond to a point on a mean path that consists of a number of concatenated straight line segments. The model characterizes both the deviation of the trajectory from the mean path and the deviation from the mean rate at which the vectors move through the vector space in a way that avoids the conditional independence assumption implicit in hidden Markov modeling. The model is formulated using a state space approach in which the state vector consists of only two elements. These represent the position on the mean path corresponding to the present observation vector and the rate at which points on the mean path are moving through the vector space. A method for estimating the parameters of the model using the Expectation Maximization algorithm is presented

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  • A preliminary study of the effect of surface coating on the initial deposition mechanisms of dairy fouling.

    Ramachandra, S. S.; Wiehe, S.; Hyland, M. M.; Bansal, B. (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Modification of heat transfer surfaces to minimize the effects of fouling in the dairy industry is investigated in the current study. Special attention is given to the initial deposition mechanisms, which are believed to determine the fouling and cleaning performance of the surfaces studied. Preliminary results have been obtained for stainless steel and titanium nitride (TiN) surfaces fouled for 3 minutes with whey protein and calcium phosphate. Scanning Electron Microscopy (SEM) images of air-dried, whey protein fouled samples showed both TiN and stainless steel surfaces were covered with a thin layer of deposit, following the topography of the heating surface. X-ray Photoelectron Spectroscopy (XPS) spectra for the TiN surfaces fouled with whey protein showed carbon and oxygen as the main components present. XPS analysis of the stainless steel surfaces is currently underway. Calcium phosphate fouling on stainless steel and TiN surfaces resulted in formation of a crystal matrix on some parts of the surface, while other parts appeared to have no deposition. X-ray microanalysis of these crystals yielded a Ca/P ratio of 1.4. X-ray Diffraction (XRD) analysis is being undertaken to better identify the phases formed. Also in consideration is SEM analysis under cryogenic conditions, and XPS analysis of freeze-dried samples to eliminate changes taking place during air-drying. Future experiments will involve fouling of diamond-like carbon (DLC) surfaces. It is expected that altering the fouling behavior and therefore deposit adhesion, may influence cleaning performance, which will be tested in cleaning runs. At a later stage, similar investigations will be performed using milk solutions to study the combined effect of proteins and minerals.

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  • A Comparison of Multilevel Solvers for the Cardiac Bidomain Equations

    Austin, Travis; Trew, Mark; Pullan, Andrew (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Computing the extracellular potentials in a bidomain cardiac activation model is a computationally significant step in the solution process. Thus, using a fast solver can drastically reduce the overall time of simulation. Solving for the extracellular potentials involves inverting the matrix coming from the elliptic equation describing the extracellular-intracellular potential coupling. Elliptic equations are known to yield matrices that become progressively more ill-conditioned as the spatial resolution is increased. However, optimal multilevel solution methods are known to exist for these equations given enough effort is placed into developing the correct solution components. Two multilevel solvers that automatically perform much of this work are Black Box Multigrid (BOXMG) and Algebraic Multigrid (AMG). In this paper, we compare the performance of BOXMG and AMG as solvers for the elliptic component of the bidomain equations. Our investigation is with respect to simulations of reentry in two-dimensional cardiac tissue.

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  • Evaluation of the effect of postural and gravitational variations on the distribution of pulmonary blood flow via an image-based computational model

    Burrowes, Kelly; Hunter, Peter; Tawhai, Merryn (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. We have developed an image-based computational model of blood flow within the human pulmonary circulation in order to investigate the distribution of flow under various conditions of posture and gravity. Geometric models of the lobar surfaces and largest arterial and venous vessels were derived from multi-detector row x-ray computed tomography. The remaining blood vessels were generated using a volume-filling branching algorithm. Equations representing conservation of mass and momentum are solved within the vascular geometry to calculate pressure, radius, and velocity distributions. Flow solutions are obtained within the model in the upright, inverted, prone, and supine postures and in the upright posture with and without gravity. Additional equations representing large deformation mechanics are used to calculate the change in lung geometry and pressure distributions within the lung in the various postures - creating a coupled, co-dependent model of mechanics and flow. The embedded vascular meshes deform in accordance with the lung geometry. Results illustrate a persistent flow gradient from the top to the bottom of the lung even in the absence of gravity and in all postures, indicating that vascular branching structure is largely responsible for the distribution of flow.

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  • High Resolution 3D Imaging of Lung Tissue using Structured Light Microscopy

    Kvistedal, Yme; Tawhai, Merryn; Hunter, Peter; Nielsen, Poul (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. A 3D reconstruction microscope has been built in order to investigate the structural details of the airway tree and the vasculature of mouse lungs. The objective is to create an anatomically correct finite element model of a mouse lung in order to validate results from simulations obtained using an existing model of the human lung. The 3D reconstruction microscope consists of a fully automated scanning stage, a vibratome and a structured light optical microscope. Structured light microscopy is a new approach to optical sectioning of tissue and offers several advantages over confocal microscopy.

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  • A Replicated Comparison of Cross-Company and Within-Company Effort Estimation Models Using the ISBSG Database

    Mendes, Emilia; Lokan, Chris; Harrison, Robert; Triggs, Christopher (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Four years ago was the last time the ISBSG database was used to compare the effort prediction accuracy between cross-company and within-company cost models. Since then more than 2,000 projects have been volunteered to this database, which may have changed the trends previously observed. This paper therefore replicates a previous study by investigating how successful a cross-company cost model is: i) to estimate effort for projects that belong to a single company and were not used to build the cross-company model; ii) compared to a within-company cost model. Our within-company data set had data on 184 software projects from a single company and our cross-company data set employed data on 672 software projects. Our results did not corroborate those from the previous study, showing that predictions based on the within-company model were not significantly more accurate than those based on the cross-company model. We analysed the data using forward stepwise regression.

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  • 65 THz beat frequency observed from a scalar modulation instability experiment

    Kruhlak, Robert; Wong, Gordon; Clark, Heather; Leonhardt, Rainer; Harvey, John; Knight, J C; Wadsworth, W J; Russell, P St. J (2005)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. We have observed an optical modulation with a period of about 15 fs by beating the anti-stokes wave and the pump wave exiting a photonic crystal fibre. These results confirm the coherence of the sidebands generated by scalar modulation instability in the normal dispersion regime. Future experiments will be conducted to measure the beating of the stokes and the anti-stokes waves.

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  • A Java reuse repository for Eclipse using LSI

    Lin, Min Yang (Jerry); Amor, Robert; Tempero, Ewan (2006)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Software reuse is a concept that is frequently mentioned as a way to improve software developers' productivity. However, there are a number of issues that need to be addressed in order for software reuse to be adopted by developers. One of those issues is providing enough reusable artifacts. The Java Standard API has been quite successful in this, with the latest version having over 3000 classes available. However this raises the issue of finding the right artifact to reuse. With the Java API, this means trawling through the JavaDoc Web pages, which has the risk of not being able to find the right artifact, even though it is in the API. In this paper, we explore the use of latent semantic indexing as a means to index the Java API JavaDoc pages. Specifically, we describe Prophecy, an Eclipse plug-in that presents the Java API as a software repository.

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