423 results for Conference item, 2010

  • Very low frequency supercapacitor techniques to improve the end-to-end efficiency of DC-DC converters based on commercial off the shelf LDOs

    Kularatna, Nihal; Fernando, Jayathu; Kankanamge, Kosala; Tilakaratna, L. (2010)

    Conference item
    University of Waikato

    Given the advantages of linear regulator techniques, low dropout regulator ICs are frequently used in portable consumer electronics. Only disadvantage in linear regulators, low efficiency, can be overcome by a very low frequency supercapacitor energy recovery technique to achieve efficiencies similar to common switching regulator techniques. This technique was successfully applied in a 12 V to 5 V regulator. The article provides some generalized theoretical background and different supercapacitor circulating options which can be applied to different cases of linear regulators.

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  • Investigation of failure patterns of desktop computer power supplies using a lightning surge simulator and the generation of a database for a comprehensive surge propagation study

    James, Sisira; Kularatna, Nihal; Steyn-Ross, D. Alistair; Pandey, A.; Künnemeyer, Rainer; Tantrigoda, D. (2010)

    Conference item
    University of Waikato

    According to the International Technology Roadmap for Semiconductors (ITRS) future VLSI devices of gigahertz capability are expected to have feature sizes below 45 nm with DC power supply requirements with sub 1V and the equivalent noise voltages close to the DC rail values. This scenario makes the surge resist capability of processor type loads and the associated power conversion interfaces with lot of power semiconductors, seriously vulnerable to lightning and other power transients. In a major research project to predict the propagation of transients within the power conversion interfaces using wavelet transform, it was necessary to develop an experimental database of surge failures in power electronic subsystems. This paper highlights the results of destructive testing of desk top PC power supplies using a lightning surge simulator which will be used for comparing experimental data with analytical/simulated results.

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  • Developing usability studies via formal models of UIs

    Bowen, Judy; Reeves, Steve (2010)

    Conference item
    University of Waikato

    Developing usability studies to evaluate software is a task requiring a wide variety of skills. For software developers who are not used to taking a user-centred approach to development it is often easier and more convenient to dismiss the use of user evaluation as too time-consuming or too hard. This is even more likely to be the case for developers who take a formal approach to software development, which is generally not focused on interface or usability concerns. In this paper we present an early investigation into the use of formal models of user interface designs as the basis for designing software evaluation studies. We have undertaken a comparison study to find out whether a useful study can be derived in this way and whether or not further investigation into this is worthwhile, and we present the results here.

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  • Surge endurance capability testing of supercapacitor families

    Kularatna, Nihal; Fernando, Jayathu; Pandey, A. (2010)

    Conference item
    University of Waikato

    Supercapacitors are usually low voltage, high capacity devices with milliohm order equivalent series resistances. They usually have time constants from fractional seconds to seconds. Due to these long time constants, compared to the time durations of power line transients in the range of few microseconds to several 100 microseconds, these devices may be able to withstand short duration surges with energy values specified in IEEE C62-41 series and IEC 61400-4-5 and similar standards. However there is little or no manufacturer data sheet information on these aspects. The paper provides the details of a test procedure to test the surge withstand capability of supercapacitors. In addition, essential details of a customized tester interface required for a lightning surge simulator and surge-endurance test results for three supercapacitor families are also presented.

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  • Organizing self-organizing teams

    Hoda, Rashina; Noble, J; Marshall, S (2010)

    Conference item
    The University of Auckland Library

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  • Perceptual Training of Tinnitus

    Jepsen, K; Sanders, Michael; Searchfield, Grant; Kobayashi, Kei (2010)

    Conference item
    The University of Auckland Library

    It is currently believed that the majority of tinnitus is a consequence of changes in the central auditory pathways following peripheral injury. This change in brain function is known as plasticity. Another form of plasticity occurs as a process of learning or training. The basis of perceptual training is that by exposure to sensory stimuli we learn, usually improving perceptual skills. Perceptual training usually requires the listener to be actively involved in listening and responding to training sounds, unlike sound therapy used in masking or habituation therapies where listeners are passively exposed to sounds. In this paper various forms of perceptual training are introduced before describing Frequency Categorisation Training (FCT) and Frequency Discrimination Training (FDT) and their effects on Tinnitus and late Auditory Evoked Potentials (AEP). Twenty participants underwent assessment and training. Assessment of tinnitus handicap rating and the P1-N1-P2 AEP complex (64 channel BioSemi EEG system) at pitch match, one octave below pitch match and at 750 Hz were undertaken before and after participants completed FCT or FDT for 21 training sessions over 3 weeks. Auditory training was carried out daily in the participants own home using a Palm Tungsten E2 PDA. The THI score reduced by 5.11 points following FDT. Ability to ignore tinnitus improved by 1.36 points following FCT on a ten point rating scale. An increase in average absolute N1 amplitude was seen following FCT, compared to decrease seen following FDT. Similar changes were not observed for the P2 waveform. The results of this study suggest that short-duration perceptual training can contribute to a reduction in tinnitus perception and that these perceptual changes can be observed as changes in auditory evoked potentials.

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  • Knowing Our Place: Critical Multicultural Science Education

    Stewart, Georgina (2010)

    Conference item
    The University of Auckland Library

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  • Testing of unreinforced masonry walls seismically retrofitted with ECC shotcrete

    Lin, Yi-Wei; Ingham, Jason; Lawley, Derek (2010)

    Conference item
    The University of Auckland Library

    Engineered Cementitious Composite (ECC) is a type of strain-hardening cement composite that was sprayed onto unreinforced masonry (URM) walls in order to determine the suitability of using this method of application as a seismic retrofitting technique for URM buildings. From studies considering the mix design of ECC it was determined that sand is a crucial component influencing the strain-hardening behaviour. Following improvement of the sand used, an ECC with an ultimate tensile strain capacity of 2% was obtained and three brick high prism samples with ECC sprayed onto one face were tested in axial compression and found to exhibit five times the energy absorption of the non-retrofitted prisms when using 10 mm of ECC reinforcement. Retrofitted masonry wallettes were tested to determine their diagonal in-plane response and results showed that ECC had successfully modified the brittle behaviour of non-retrofitted samples, to instead exhibit ductile behaviour. Finally, two 4.1 m high walls were constructed to test out-of-plane response. It was determined that 30 mm of ECC was able to increase the out-of-plane load capacity of the wall by a factor of 13.2 when sprayed on the tension surface and increased the load capacity of the wall by a factor of 1.6 when applied on the compression surface. It is concluded that ECC is an effective material for both in-plane and out-of-plane seismic retrofitting of URM buildings

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  • Sentiment knowledge discovery in Twitter streaming data

    Bifet, Albert; Frank, Eibe (2010)

    Conference item
    University of Waikato

    Micro-blogs are a challenging new source of information for data mining techniques. Twitter is a micro-blogging service built to discover what is happening at any moment in time, anywhere in the world. Twitter messages are short, and generated constantly, and well suited for knowledge discovery using data stream mining. We briefly discuss the challenges that Twitter data streams pose, focusing on classification problems, and then consider these streams for opinion mining and sentiment analysis. To deal with streaming unbalanced classes, we propose a sliding window Kappa statistic for evaluation in time-changing data streams. Using this statistic we perform a study on Twitter data using learning algorithms for data streams.

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  • Speeding up and boosting diverse density learning

    Foulds, James Richard; Frank, Eibe (2010)

    Conference item
    University of Waikato

    In multi-instance learning, each example is described by a bag of instances instead of a single feature vector. In this paper, we revisit the idea of performing multi-instance classification based on a point-and-scaling concept by searching for the point in instance space with the highest diverse density. This is a computationally expensive process, and we describe several heuristics designed to improve runtime. Our results show that simple variants of existing algorithms can be used to find diverse density maxima more efficiently. We also show how significant increases in accuracy can be obtained by applying a boosting algorithm with a modified version of the diverse density algorithm as the weak learner.

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  • Fast perceptron decision tree learning from evolving data streams

    Bifet, Albert; Holmes, Geoffrey; Pfahringer, Bernhard; Frank, Eibe (2010)

    Conference item
    University of Waikato

    Mining of data streams must balance three evaluation dimensions: accuracy, time and memory. Excellent accuracy on data streams has been obtained with Naive Bayes Hoeffding Trees—Hoeffding Trees with naive Bayes models at the leaf nodes—albeit with increased runtime compared to standard Hoeffding Trees. In this paper, we show that runtime can be reduced by replacing naive Bayes with perceptron classifiers, while maintaining highly competitive accuracy. We also show that accuracy can be increased even further by combining majority vote, naive Bayes, and perceptrons. We evaluate four perceptron-based learning strategies and compare them against appropriate baselines: simple perceptrons, Perceptron Hoeffding Trees, hybrid Naive Bayes Perceptron Trees, and bagged versions thereof. We implement a perceptron that uses the sigmoid activation function instead of the threshold activation function and optimizes the squared error, with one perceptron per class value. We test our methods by performing an evaluation study on synthetic and real-world datasets comprising up to ten million examples.

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  • 10Gb/s Error Free Transmission through Micro-Structured Multimode Polymer Optical Fibers

    Provo, Richard; Murdoch, Stuart; Harvey, John; Lwin, R; Large, M (2010)

    Conference item
    The University of Auckland Library

    We demonstrate for the first time 10Gb/s error-free transmission through two differently micro-structured-multimode polymer fibers. Results show excellent transmission characteristics for these fibers and demonstrate that micro-structuring can significantly improve the bandwidth of multimode-polymer fibers.

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  • Social Networking Technologies to Implement Adaptive Business Networks

    Zeng, B; Dong, Ching-Shen; Srinivasan, Ananth (2010-10)

    Conference item
    The University of Auckland Library

    In this paper we present a proposal for the utilization of social network technologies to implement adaptive business networks. Organizations are increasingly reliant on models of coordination and cooperation. Traditional approaches to defining and implementing business processes are deficient in addressing cross organizational models. We propose that such models can be usefully supported by social networking technologies that have rapidly grown to be effective platforms for collaboration among individuals.

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  • Experimental Demonstration of Phase Matching Curve for Bragg Scattering in a Positive Beta 4 Fiber

    Provo, Richard; Murdoch, Stuart; Harvey, John; M??chin, D (2010)

    Conference item
    The University of Auckland Library

    We experimentally demonstrate the phase matching curve for the Four-Wave-Mixing effect of Bragg Scattering in two Highly-Nonlinear-Fibers with opposite sign 4th order dispersion coefficients. The experimental results are fitted to theoretical predictions with good agreement.

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  • Leveraging bagging for evolving data streams

    Bifet, Albert; Holmes, Geoffrey; Pfahringer, Bernhard (2010)

    Conference item
    University of Waikato

    Bagging, boosting and Random Forests are classical ensemble methods used to improve the performance of single classifiers. They obtain superior performance by increasing the accuracy and diversity of the single classifiers. Attempts have been made to reproduce these methods in the more challenging context of evolving data streams. In this paper, we propose a new variant of bagging, called leveraging bagging. This method combines the simplicity of bagging with adding more randomization to the input, and output of the classifiers. We test our method by performing an evaluation study on synthetic and real-world datasets comprising up to ten million examples.

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  • Enhanced spatial pyramid matching using log-polar-based image subdivision and representation

    Zhang, Edmond Yiwen; Mayo, Michael (2010)

    Conference item
    University of Waikato

    This paper presents a new model for capturing spatial information for object categorization with bag-of-words (BOW). BOW models have recently become popular for the task of object recognition, owing to their good performance and simplicity. Much work has been proposed over the years to improve the BOW model, where the Spatial Pyramid Matching (SPM) technique is the most notable. We propose a new method to exploit spatial relationships between image features, based on binned log-polar grids. Our model works by partitioning the image into grids of different scales and orientations and computing histogram of local features within each grid. Experimental results show that our approach improves the results on three diverse datasets over the SPM technique.

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  • Improving Bag-of-Words model with spatial information

    Zhang, Edmond Yiwen; Mayo, Michael (2010)

    Conference item
    University of Waikato

    Bag-of-Words (BOW) models have recently become popular for the task of object recognition, owing to their good performance and simplicity. Much work has been proposed over the years to improve the BOW model, where the Spatial Pyramid Matching technique is the most notable. In this work, we propose three novel techniques to capture more re_ned spatial information between image features than that provided by the Spatial Pyramids. Our techniques demonstrate a performance gain over the Spatial Pyramid representation of the BOW model.

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  • Resourcing a research culture: the roles of the library and the research assistant at Whitireia Community Polytechnic

    Parker, Ailsa (2010-01-08)

    Conference item
    Whitireia Community Polytechnic

    In 1994 the New Zealand Qualifications Authority granted Whitireia Community Polytechnic approval for a nursing degree and in the year 2000, the School of Computing introduced a Bachelor of Information Technology. The granting of these degrees, with their research component, has meant that a research culture has had to be developed. Characteristics of productive research environments have been identified as including resources, particularly human resources. Since staff teaching on a degree programmes have to be actively engaged in research, there is increasing pressure to teach as well as research. As with many tertiary institutions, this demand often puts staff in an unbalanced situation, unable to find the time for research given a sometimes heavy teaching load. The institution has reacted to this pressure and new patterns of support are emerging. A case study approach, using organisational role theory, is used to examine Whitireia Community Polytechnic's strategies of resourcing research and researchers. Documentary sources such as reports and policy documents and participant-observations are used to analyse the roles of the research assistant and of library services. The primary function of these supporting roles is to be of practical and academic assistance and to ensure that the staff are properly channeled through the necessary research processes and networks that could help them. The efficacy of these roles at Whitireia Community Polytechnic is discussed in terms of research literature and role theory. Both roles, in different ways, were found to be contributing to a productive research environment. Suggestions are made for future research.

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  • Library website accessibility: a case study

    Parker, Ailsa (2010-01-08)

    Conference item
    Whitireia Community Polytechnic

    Libraries devote considerable time and expense to ensuring that disabled users can physically access the library. Is the same amount of thought, however, going into Web page development. Do sites provide support for technologies such as audio readers? Are they compliant with the W3C Web Accessibility Initiative standards? This presentation discusses Bobby, a free software that can quickly check for compliance; shares research results of testing the Web pages of New Zealand polytechnic libraries with Bobby; and compares the results with overseas research.

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  • Where are beginning teachers' stories about learning to teach in culturally and socially diverse secondary school classrooms?

    Patrick, Rachel (2010-01-11)

    Conference item
    Whitireia Community Polytechnic

    This paper reviews the literature related to an in-depth, narrative study currently being carried out on how beginning secondary teachers in culturally and socially diverse classrooms in New Zealand shape their professional knowledge and practice. Recent governmental reports from New Zealand, Australia and the UK highlight ongoing concern about beginning teacher retention and about the variability of the quality of new teacher induction programmes. The literature explored in this paper also discusses the issues for teachers arising from recent social and technological changes and the development of new teachers' professional knowledge. Little research has been found, to date, about the perspectives of the beginning teachers. This paper argues for the need to find out, from beginning teachers themselves, how they experience and represent the professional, political, social and cultural issues they face. This is presented as necessary if we are to understand better how to harness their expertise and commitment in schools, and prepare teachers who have a positive impact on the quality of outcomes for diverse students.

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