106 results for Conference paper, ResearchSpace@Auckland

  • A simulation model for the dynamic allocation of network resources in a competitive wireless scenario

    Beltran, Fernando; Roggendorf, Matthias (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. Next-generation wireless networks will enable the usage of different network technologies fully transparent to the user. Applications will be able to dynamically adapt to the conditions and technical constraints of the network. This vision requires a dynamic allocation of scarce network resources to different users. This paper presents simulation results from a model of admission control and dynamic resource allocation in wireless networks, in a two-provider, multiple-user scenario. The access allocation and connection procedure is implemented using an efficient (welfare maximizing) incentive mechanism for capacity allocation at both providers.

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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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  • Feedback model for an insect circadian clock

    Lewis, Robert D. (1988)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Hemideina thoracica is a nocturnal orthopteran insect which exhibits clear circadian locomotor rhythmicity in constant conditions. Analysis of the free-running rhythms leads to the hypothesis that the underlying clock mechanism has two major interacting components, one responsible for the overt locomotor rhythm, and another whose output is not directly related to locomotor activity. A model comprising two linked populations of feedback oscillators accounts for much of the free-run liability seen in the real data.

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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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  • Aging gracefully? Reviewing and enhancing Information Commons services at the University of Auckland

    Chidlow, Rachel; Mountifield, Hester (2010)

    Conference paper
    The University of Auckland Library

    Conference programme and links to all papers http://www.vala.org.au/vala2010/prog2010.htm The University Library’s Information Commons Group services and facilities have continued to thrive and improve student life and learning since the opening of the Kate Edger Information Commons in April 2003. The IC Group has a strong strategic focus on continuous improvement in areas of management, staff development, operations, space design, technology, resource development and client services. The IC Group collaborates with ITS in offering and improving electronic campus services for students. This paper outlines the “how” and “why” behind changes and improvements in the IC Group. The benefits to staff and students will also be demonstrated. This paper also briefly discusses the reengineering of the original service model to accommodate changes in learning, technology and student needs.

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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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  • Interaction of whey protein with modified stainless steel surfaces.

    Premathilaka, S. S.; Hyland, M. M.; Chen, Z. D.; Watkins, L. R.; Bansal, B. (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. Modified stainless steel surfaces were fouled with whey protein solutions to study the deposition mechanisms and the effects of surface modification. Stainless steel samples were coated with diamond-like carbon (DLC) and titanium nitride (TiN). These surfaces are expected to present different surface chemistries to stainless steel in terms of their functional groups and hydrophobic or hydrophilic nature. Thus, it is expected that foulant-surface interactions will differ for the various fouled surfaces. The substrates were exposed to a flowing whey protein solution in a fouling rig designed to achieve laminar flow. X-ray Photoelectron Spectroscopy (XPS) was used to study the initial protein-surface interactions of samples fouled for 1 minute at 75°C. Ellipsometry was used to study the fouling and cleaning performance of samples fouled at 75°C and 85°C for up to 30 minutes followed by ultrasonic caustic cleaning of selected samples. XPS showed the presence of similar protein functional groups on all fouled surfaces. The bonding mechanisms during fouling of DLC is different to the stainless steel and TiN surfaces. The peptide link played a more active role at the deposit-surface interface for the non-polar DLC surface, while it was less significant for the two polar surfaces. Ellipsometry revealed that for the three surfaces, fouling increased in the order DLC<DLC. Furthermore, the nature of the surface influenced the structure of the deposit after the initial protein layer was formed. It was concluded that the surface chemistry can influence the deposition mechanisms in terms of the orientation of protein functional groups as well as the amount of fouling, the structure of the deposit and hence the deposit removal behaviour.

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  • Modelling the pelvic floor for investigating difficulties during childbirth

    Li, XS; Kruger, JA; Chung, JH; Nash, MP; Nielsen, PMF (2008)

    Conference paper
    The University of Auckland Library

    Research has suggested that athletes involved in high-intensity sports for sustained periods have a higher probability of experiencing prolonged second stage of labour compared to non-athletes. The mechanism responsible for this complication is unknown but may depend on the relative size or tone of the pelvic floor muscles. Prolonged training can result in enlargement and stiffening of these muscles, providing increased resistance as the fetal head descends through the birth canal during a vaginal birth. On the other hand, recent studies have suggested an association between increased muscle bulk in athletes and higher distensibility. This project aims to use mathematical modelling to study the relationship between the size and tone of the pelvic floor muscles and the level of difficulty during childbirth. We obtained sets of magnetic resonance (MR) images of the pelvic floor region for a female athlete and a female non-athlete. Thirteen components of the pelvic floor were segmented and used to generate finite element (FE) models. The fetal head data was obtained by laser scanning a skull replica and a FE model was fitted to these data. We used contact mechanics to simulate the motion of the fetal head moving through the pelvic floor, constructed from the non-athlete data. A maximum stretch ratio of 3.2 was induced in the muscle at the left lateral attachment point to the pubis. We plan to further improve our modelling framework to include active muscle contraction and fetal head rotations in order to address the hypotheses that there is a correlation between the level of difficulty and the size or tone of the pelvic floor muscles.

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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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  • Internet Applications for Computational Biology, the CMISS Web Browser Extension and and Use in Education

    Stevens, Carey; Blackett, Shane; LeGrice, Ian; Hunter, Peter (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 internet is becoming increasingly accessable and new technologies are enabling the delivery of more features to end users. It is therefore increasingly compelling to develop technology to facilitate the delivery of educational content and computational tools via the internet. Here we report on the internet enabling of the CMISS package as a web browser extension, and its use in a custom online teaching application for medical students.

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  • Controlling Inrush Currents in Inductively Coupled Power Systems

    Boys, John T.; Chen, C.I.; 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. In an Inductively Coupled Power Transfer (ICPT) system, a multiplicity of (moving) loads take power from an elongated conductive loop (track) excited by a current in the range of 15-125A by magnetic induction at a VLF frequency of between 5-50kHz. In this application, the track performs the same function as a distribution line in a power system. However, frequency deviations cannot be tolerated in ICPT systems and therefore there are difficulties with inrush power surges as loads switch on. In severe cases, the inrush surge may compromise the security of the whole system. This paper proposes a solution to this problem using an ICPT pickup controller with input shaping where the poles that can cause an inrush are not excited. The paper is supported by theoretical analysis and experimental measurements and is applicable across a wide range of ICPT sizes and applications. The solution reduces the inrush effects to 10% of an uncontrolled system.

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  • Reuse of Components in Formal Modeling and Verification of Distributed Control Systems

    Vyatkin, Valeriy; Hanish, Hans-Michael (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. This paper describes formal modeling and verification of automation systems ftom the system engineering point of view. Reuse of model components is the key issue in order to bring the scientific modeling methodology into engineering practice. The reuse is achieved by the combination of modular modeling of automation systems with object-oriented description of models in UML style. This allows to benefit from advantages of both worlds: efficiently manage highly hierarchical complex models with UML tools and end up with efficiently executable models with distributed states that are compatible also with IEC61499 function block specifications. The approach is supported by the tool framework that is described in the contribution.

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  • Using CellML in Computational Models of Multiscale Physiology

    Nickerson, David; Hunter, Peter (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 computational modeling framework is presented which enables the integration of multiple physics and spatial scales in models of physiological systems. A novel aspect of the framework is the use of CellML to specify all model and simulation specific mathematical equations including cellular models and material constitutive relationships. Models of cardiac electromechanics at cellular, tissue, and organ spatial scales are used to illustrate the developed and implemented framework and other applications are discussed.

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  • Qualitative spatial reasoning under uncertainty in geographical information systems

    Loerch, Ute; Guesgen, Hans W. (1997)

    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 capability of geographical information systems (GIS) to display images and analyse them is one of the most powerful features, because people have a very consistent ability to reason about visual features according to their own knowledge model. Usually the abilities of GIS are restricted in dealing with quantitative data only, so that they fail whenever exact matches cannot be found. A solution to this problem is not only to allow the quantitative information, but also qualitative one. Proximity factors such as `close to' and `far from' are included. The qualitative approach offers a more natural way for the user of the system to specify what he actually wants, by using the proximity operators. This paper is an attempt of integrating qualitative spatial reasoning into geographic information systems. The idea is to associate qualitative information with fuzzy sets and to use the values of these fuzzy sets for spatial reasoning. The authors are concerned with the problem of image interpretation, which stands for the geometric and semantic recognition of the objects contained in one image

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  • Processing temporal aggregates in parallel

    Ye, Xinfeng; Keane, John A. (1997)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Temporal databases maintain past, present and future data. TSQL2 is a query language designed for temporal databases. In TSQL2, the GROUP BY clause has the temporal grouping property. In temporal grouping, the time line of each attribute value is partitioned into several sections, and aggregate functions are computed for each time partition. This paper describes two approaches to parallelising an algorithm for computing temporal aggregates. The two approaches have been implemented on an SGI PowerChallenge SMP parallel system. The experimental results show that the performance of the two approaches depends on data skew ratio and the number of processors used in the computation

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  • Petri net-based visual language for specifying GUIs

    Li, Xiaosong; Mugridge, Warwick B.; Hosking, John G. (1997)

    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 describe PUIST, a visual language for graphical interface specification and prototyping. PUIST uses a Petri net notation, with a declarative means of defining nets which have complex, yet regular interconnections. This significantly improves the understandability of large specifications, permitting PUIST to be used for complex interface component specification and prototyping

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  • Petri net-based environment for GUI design

    Li, Xiaosong; Mugridge, Warwick B.; Hosking, John G. (1997)

    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 describe PUIST, a visual environment for graphical user interface specification and prototyping. PUIST uses a Petri net notation, with a declarative means of defining nets which have complex, yet regular interconnections. This significantly improves the understandability of large specifications, permitting PUIST to be used for complex interface component specification, analysis and prototyping

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