106 results for The University of Auckland Library, Conference paper

  • 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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  • 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 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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  • 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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  • 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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  • 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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  • ION architecture for robot learning

    Qualtrough, Paul (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. It is claimed that one of the main reasons why the development of intelligent robots has been slower than expected is that machine learning has been seen as an “add on” feature-one to be placed in the higher and later-developed levels of robot architectures. A case is made for incorporating machine learning at the earliest possible stage, and relying on it as the primary method of developing robot controllers. An architecture is proposed to support this approach

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  • Adaptive fuzzy control

    Li, Han-Xiong (1996)

    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 this paper, adaptive fuzzy logic control (FLC) will be designed by using a simple reference model. This design approach is based on our new methodology “design rule base qualitatively and data base quantitatively”. If the linear rule base is used, the model of FLC can be obtained. It is actually a nonlinear function with only three scaling gains need to be designed and tuned. The conventional control theory can thus be used. This model reference adaptive fuzzy control (MRAFC) requires less restriction on the reference model, but often achieves a more robust performance than its classical counterpart

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  • Efficient word-graph parsing and search with a stochastic context-free grammar

    Waters, C.J.; MacDonald, B.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. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher.

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  • Recovery effect in cellular radio systems

    Carter, L.J.; Maclean, T.S.M. (1990)

    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 expression for the attenuation of a radio wave propagating over a mixed land-sea path successfully predicts the recovery of field strength over the sea path. An initial series of measurements has been made in the Auckland area to determine whether the recovery effect is a significant factor at cellular radio frequencies. The results presented are limited by the fact that they were taken in a real environment, rather than in controlled laboratory conditions. It is therefore difficult to eliminate unwanted variables, particularly the effects of clutter. Nevertheless, the results do show consistently that signal enhancement occurs over a sea-water path at cellular radio frequencies

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  • Implications of propagation modeling on the design of a DS-CDMA in-building mobile communication system

    Butterworth, K.S.; Sowerby, K.W.; Williamson, A.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. This paper investigates the implications of propagation modeling on the design of a DS-CDMA in-building mobile communication system. Two modeling approaches are considered, namely a floor-averaged propagation model and a localised area model that considers individual propagation paths for a range of potential mobile user locations. Results (measured at 1.8 GHz) show that overall system performance estimates are heavily dependent on the model used to describe the building's propagation characteristics and suggest that the former approach leads to a rather pessimistic prediction of system performance when compared with the later. This suggests that unnecessarily conservative design would be likely if the former approach was utilised as part of a system planning process

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  • Feasibility of spectrum sharing between DS-CDMA mobile radio systems and microwave point-to-point links

    Marshall, P.J.; Sowerby, K.W.; Shafi, M. (1996)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Radio spectrum allocated for many second and third generation mobile radio systems in the 1-3 GHz frequency bands (e.g. USA PCS, DCS1800 and FPLMTS) is currently used in many countries for fixed point-to-point microwave links. General techniques are presented to investigate the feasibility of spectrum sharing between an indoor DS-CDMA mobile radio system with vertical frequency reuse and a fixed point-to-point microwave link. Using a range of system parameters, the limitations of spectrum sharing are estimated. The results indicate that, for the systems considered, spectrum sharing will be difficult to implement without sufficient geographical isolation between the two systems. It is also apparent that the feasibility of spectrum sharing depends largely on the propagation characteristics between the two systems. The feasibility of spectrum sharing depends on the mutual and self-interference that will be received in the fixed and mobile systems. General techniques for characterising this interference and determining the feasibility of spectrum sharing are outlined

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  • Self synchronising T-codes to replace Huffman codes

    Higgie, Gavin R. (1993)

    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 recent work on the T-Codes, which are a new class of variable length codes with superlative selfsynchronizing properties. The T-Code construction algorithm is outlined, and it is shown that in situations where codeword synchronization is important the T-Codes can be used instead of Huffman codes, giving excellent self-synchronizing properties without sacrificing coding efficiency

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  • Public-sector vs. private-sector R&D in India: a comparative analysis of two R&D teams

    Sankaran, Jayaram K.; Suchitra, Mouly V. (1996)

    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 subject of this paper is a comparative analysis of two Indian R&D teams with similar objectives and activities. The team which we first studied (team A) was located in a public-sector electrical power research institute. The second team (team B) was the R&D unit of a private-sector company which manufactures and sells electrical equipment such as motors, generators, and transformers. Using qualitative methodology, we developed a process model of the ineffectiveness of team A. This model served as an interpretive framework with which to study team B and compare it with team A

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  • IMECO: A reconfigurable FPGA-based image enhancement co-processor framework

    Salcic, Z.; Sivaswamy, J. (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. This paper presents a way to improve the computational speed of image contrast enhancement using low-cost FPGA-based hardware primarily targeted to X-ray images. The enhancement method considered here consists of filtering via the high boost filter (HBF), followed by histogram modification using histogram equalisation (HE). An image enhancement co-processor (IMECO) concept is proposed that enables efficient hardware implementation of enhancement procedures and hardware/software co-design to achieve high-performance, low-cost solutions. The co-processor runs on an FPGA prototyping ISA-bus board. It consists of two hardware functional units that implement HBF and HE and can be downloaded onto the board sequentially or reside on the board at the same time. These units represent an embryo of virtual hardware units that form a library of image enhancement algorithms. In trials with chest X-ray images performance improvement over software-only implementations was more than two orders of magnitude, thus providing real-time or near real-time enhancement

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  • Multicast primitive for mobile hosts

    Ye, Xinfeng; Keane, John A. (1996)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Due to network latency and the mobility of the host, many existing group communication protocols are limited to a static environment. This paper presents a multicast primitive for delivering multicast messages to mobile hosts. The primitive has the total ordering property which guarantees the ordering of message delivery. The protocol also guaranteed that the messages are delivered to the mobile hosts exactly once. Sequence numbers and message buffers are used to cope with message duplication and message loss

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  • Fuzzy exposure model

    Rajkumar, T.; Guesgen, Hans W. (1996)

    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 fuzzy exposure model which deals with the uncertainties involved in analysing prolonged (chronic) chemical exposure for humans in risk assessment. The imprecise input information for the exposure model is expressed as fuzzy sets using linguistic variables such as high, low and constant. The risk assessor can extend these fuzzy sets with respect to the data availability. The result obtained from the calculations is a fuzzy number that indicates the life average daily exposure (LADE) to human beings. A case study is illustrated to present the methodology

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  • Detecting termination in static and dynamic systems

    Ye, Xinfeng; Keane, John A. (1996)

    Conference paper
    The University of Auckland Library

    An open access copy of this article is available and complies with the copyright holder/publisher conditions. Distributed termination detection concerns detecting the termination of a distributed computation spread across a set of processors. Most solutions to the problem are not intended for dynamic systems where processes can be created and destroyed during the computation. In this paper, a termination detection algorithm which can be applied to both static and dynamic systems is proposed. The scheme can be applied to any kind of connection topology. The number of control messages is lower than some previous approaches

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