2,186 results for 1980

  • Stress : strain relationships for confined concrete : rectangular sections

    Scott, Bryan D. (1980)

    Masters thesis
    University of Canterbury Library

    An experimental investigation into the behaviour of square, confined, reinforced concrete columns was undertaken. Thirty 450 mm square, 1200 mm high units were cast with varying amounts of longitudinal and lateral steel. These were subjected to concentric or eccentric axial loads to failure at slow or dynamic loading rates. Confinement requirements of reinforced concrete columns are discussed and the results and analyses of experimental work presented. Results include an assessment of the significance of loading rate, eccentricity, amount and distribution of longitudinal steel, and the amount of confining steel. A general stress-strain curve for rectangular concrete sections loaded at seismic rates is proposed and compared with existing curves based on previous static loading tests.

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  • Engineering geological roading aggregate investigations of the Wakatipu Basin

    Watts, C. R. (1988)

    Masters thesis
    University of Canterbury Library

    The Wakatipu Basin lies within the Otago Schist belt, and aggregates derived from the schist do not meet New Zealand basecourse specifications. This study comprises engineering geological investigations of the roading aggregate with the objective of identifying potential aggregate source areas which comply with specifications. Five aggregate sources, two glacial and three post-glacial, have been identified, and their geology related to aggregate quality. A survey of existing aggregate quarries confirmed the sub-specification quality of schist derived roading aggregate, and that the highest quality roading aggregate of the Basin is produced from exotic glacial transported graywacke. A graywacke rich aggregate source area of Kame terraces was investigated. Investigations included mapping at scales of 1:10 000 and 1:1 500, and the excavation of test pits. A geotechnical testing programme concluded that the Kame terrace source area was capable of producing roading aggregate for basecourse, and is comparable with the highest quality roading aggregate of the Wakatipu Basin. Subsequently, the Queenstown - Lakes District Council has developed an aggregate quarry within the Kame terrace source area.

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  • The palynology of the Ohai coalfield, Southland

    Warnes, Malcolm D. (1988)

    Masters thesis
    University of Canterbury Library

    The Upper Cretaceous Morley Coal Measures in the Ohai Coalfield are one of three non-marine formations constituting the Ohai Group. In the past, seam correlation has generally been carried out using lithological criteria, however due to dramatic thinning and splitting of seams, associated faulting, and abrupt facies changes uncertainties in coal seam correlation have frequently arisen. In order to minimize lithostratigraphic uncertainties Couper (1964) pioneered a palynological zonation which demonstrated the potential of palynology for coal seam correlation. However, Couper's early work has proved unreliable and is in need of further refinement. Recent drillholes incorporating almost fully cored sequences of the Morley Formation have permitted further palynological examination of the coal measures. Nine drillholes were selected and 140 samples taken, at 10 metre intervals, for palynological analyses. The Morley Coal Measures are unconformably overlain by the Beaumont Coal Measures. This important boundary, though difficult to detect lithologically, is readily defined on palynological grounds. Biostratigraphic subdivision of the Morley Coal Measures was investigated by the application of three quantitative techniques. These entailed the construction and analysis of: (1) Standard pollen diagrams based on relative abundances of selected taxa and groups of taxa; (2) Pollen diagrams zoned by the numerical method of cluster analysis; (3) Ratios of selected taxa of recurrent and variably high frequency. Technique (1), involving relative abundance patterns of key taxa and groups of taxa was successful in providing a basis for subdivision of the Morley Coal Measures into three pollen zones, two interzonal units and two unzoned units. The three pollen zones were, in stratigraphically descending order: The Nothofagus kaitangata acme zone, the SPPA assemblage zone, and the Tricolpites reticulatus acme zone. Techniques (2) and (3) were, in all practicality, unproductive, although results suggested that, with refinement, cluster analysis could aid the zonation of pollen diagrams.

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  • Code optimisation for the NZTAB Pascal compiler

    Douthwaite, Ian M. (1983)

    Discussion / Working Papers
    University of Canterbury Library

    The aim of this project was optimisation of the code produced by the NZTAB Pascal compiler. This compiler is used for almost all the code in the TAB's nationwide betting system. The desire to improve the performance of the code was prompted by two reasons: * Certain heavily-used parts of the code are presently written in assembler for efficiency. For maintainability, it would be better to have all code written in Pascal. * The performance of the betting system is significantly affected by certain system control functions. The TAB wished to pursue the adding of an optimisation stage to the compiler so that performance might be improved in that way. The task of this project, then, was to consider the problem of adding optimisation to the TAB compiler, assessing possible optimisation techniques, and implementing the best of these. There are several aspects to this project and the structure of this report reflects that. This does not mean, however, that each aspect represents a chronological phase. The first section deals with the problem and with the constraints placed on possible optimisation methods. Section two briefly presents various kinds of optimisations that are often done and reviews the main methods available for doing them. In section three there is an analysis of the nature of the code currently produced by the TAB compiler and the implications of this for optimisation. Fourthly, various optimisation strategies that were considered are presented with their problems and advantages. Section five deals with two strategies for which some implementation was done, with the problems that arise in their implementation, and with their potential benefits. Finally, in section six, some questions are posed that are relevant to if and how the project should proceed and some recommendations are given. Naturally, the ideal result of such a project would have been the completion of an optimiser that performed sufficiently well for the earlier goals to be realised: this has not been achieved. One should remember though that this project can viewed in two ways. In one way it can be seen as being required to add some form of optimisation to a Pascal compiler. At the other level, however, it can be seen as ryeeding to provide optimisation that is sufficient for the goals given at the start of this introduction, and that is obtained in a way that is acceptable to the TAB environment. This latter goal is far more difficult but it is towards this goal that the efforts of this project have been directed.

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  • Packet flow analysis in X.25 public data networks : a simulation tool

    Reynolds, Paul (1984)

    Discussion / Working Papers
    University of Canterbury Library

    This report describes a Simula program designed to model the behaviour of X.25 Public Data Networks and produce statistics on various performance indices of the network. These include such indices as: - packet transfer times for each pair of nodes - time spent in each node - line utilisations - wait times for each line - buffer utilisations The user describes the network by suppling the model with information on each node and the lines that connect the nodes. This allows a large variety of X.25 network configurations to be studied.

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  • Jack McCullough : workers' representative on the Arbitration Court

    Nolan, Melanie (1985)

    Masters thesis
    University of Canterbury Library

    This biography of Jack McCullough is also the chronicle of the Canterbury Trades and Labour Council coterie he helped to organize at the turn of the century. This group of class conscious unionists attempted to persuade the nascent trade union movement to adopt their socialist objectives. This thesis examines the opposition that McCullough's coterie faced. It experienced difficulty, first, in distinguishing itself from an 'advanced' Liberal establishment in Christchurch which assiduously cultivated its working class power base. Organized Labour in Christchurch divided into Lib-Lab and Independent Labour factions. The Independent Labour unionists' attempt to use the arbitration system to rebuild class conscious unions was also vigorously opposed locally by a new managerial elite which attempted to control relations in the workplace and who had their own expectations of the Arbitration Court. McCullough's coterie's objectives were also challenged from the left by the militant Red Feds. Ultimately, however, McCullough's ideal ran aground. It was the victim not so much of the employers or the Red Feds as of a groundswell of more moderate Labour opinion which found its home in the Labour Party formed in July 1916. McCullough's coterie eventually failed in its attempt to create a democratic socialist revolution in its own lifetime based on either the trade union movement or the Labour Party. McCullough himself was thus left with his role as Workers' Representative on the Arbitration Court. Increasingly, he was to find this role impossible to sustain and resigned. His resignation and his entire career as workers' representative before the Court illustrates the difficulties faced by socialist reformers who chose to attempt to bring about reform from within the apparatus of the capitalist state.

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  • The earthquake resistance of reinforced concrete structural walls of limited ductility

    Mestyanek, J. M. (1986)

    Masters thesis
    University of Canterbury Library

    This thesis presents the results of an experimental study of three 1/3 to 1/2 scale model walls failing in shear under reversed cyclic loading. The main test parameter was the wall aspect ratio (height over length) . The following characteristics of response were considered: strength, displacement ductility, energy dissipation, and damageability. Recommendations are made for the design of future walls of limited ductility and the assessment of the likely seismic performance of existing walls that may respond primarily in a shear rather than flexural mode.

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  • Stratigraphy, structure and geological history of mid-Cretaceous sedimentary rocks across the Torlesse-like/non Torlesse boundary in the Sawtooth Range-Coverham area, Marlborough.

    Ritchie, D. D. (1986)

    Masters thesis
    University of Canterbury Library

    This thesis describes the geology of an approximately 100km2 area lying between the Clarence River and Kekerengu. The objectives were to determine the relationship of the "Torlesse-like" sawtooth Group to the late Early Cretaceous Coverham Group; to determine the relationship between the coeval Split Rock and Burnt Creek Formations within the Coverham Group; and to investigate the nature of Cretaceous events which led to the traditional differentiation into older Torlesse type "basement" and younger Cretaceous "cover". Geological mapping indicates the presence of three packets (Glencoe, Pikes and Coverham Blocks) of sedimentary rocks separated by the major Ouse and Pikes Faults. These packets comprise probable submarine fan flysch, massivE? sandstone, massive siltstone, acid tuffs and conglomerate of Sawtooth Group (Torlesse-like Urutawan - Motuan) unconformably overlain by probable slope basin flysch, massive siltstone, Inoceramus shellbed, and conglomerate of Coverham Group (non-Torlesse). The unconformity is most commonly angular but in a few places is a more subtle paraconformity. A further minor unconformity occurs at the base of the Ouse Member within the Split Rock Formation of the Coverham Group and is thought to reflect the presence of the growing Ouse Anticline. The Coverham Group rocks have similar Motuan - Teratan ages on each side of the Ouse Fault. The Split Rock Formation, previously used only for rocks in the middle Clarence Valley, has been extended to the Coverham area and used for rocks west of the Ouse Fault. The partly coeval Burnt Creek Formation east of the Ouse Fault was probably deposited some distance from the Split Rock Formation in a different basin separated by a structural high. They were juxtaposed by low angle reverse movement on the Fault in the Late Cretaceous. structural/deformation characteristics cannot be used as criteria for separating the Torlesse-like rocks from non-Torlesse rocks in the study area. It is dangerous to assume that 'Torlesseness' is a certain and particular state of deformation. Both the Torlesse (Sawtooth) and Coverham Group rocks exhibit a whole spectrum of deformation from 'broken formation' to more or less undisturbed beds. The pattern of deposition and deformation suggests an accretionary prism setting for these rocks. Sawtooth Group rocks are likely to represent 'younger' Pahau Terrane rocks which were deformed by a single intra-Motuan event either tectonic or perhaps a huge submarine slide, creating widespread unconformity between them and the Coverham Group slope deposits. Continuing instability is likely to have led to growing folds and further minor unconformities. The termination of the Rangitata Orogeny occurred in a progressive and evolutionary way representing a mid-Late Cretaceous change from a compressional subduction regime to a tensional rifting regime. Andesitic-rhyolitic volcanism was common in the late Early Cretaceous.

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  • Orbital characteristics of meteoroids

    Steel, Duncan (1984)

    Doctoral thesis
    University of Canterbury Library

    The bulk of meteoroidal particles follow pseudo-random orbits and are termed sporadic meteoroids. These are thought to be derived from the correlated streams of particles released by comets, although the mechanisms by which their orbits are dispersed have been the subject of some confusion. By developing techniques to compute the frequency of close encounters with each of the planets, and also the gross outcome of such events, it is shown that most sporadic orbits are a result of gravitational scattering by the giant planets. Jupiter plays the major role. Although catastrophic impacts with smaller particles limit the lifetimes of meteoroids, this mechanism is not responsible for the bulk of the stream disruption. With a simple model of the zodiacal cloud, the method is also used to find the collisional lifetime of meteoroids including for the first time the dependence upon inclination. The rate of meteoroid depletion by planetary collisions and hyperbolic ejections resulting from close approaches is calculated. It is found that for Jupiter-crossing meteoroids these losses are as rapid as those due to the PoyntingRobertson effect. This theory is also applied to six peculiar asteroids, including Hidalgo and Chiron. These prove to have extremely short-lived orbits: large orbital variations occur on a timescale of only ~10³ years. It is also shown that Pluto exists in its Neptune-crossing orbit solely because of the stable resonance which prohibits approaches between the two in the present epoch. The collision rate between the Apollo-Amor-Aten asteroids and each of the terrestrial planets is calculated using all 76 known objects. The result using this new procedure (4-6 Earth impacts per million years) is somewhat higher than previous estimates, indicating that these asteroids do not represent a steady-state population.

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  • Seismic resistant design of base isolated multistorey structures

    Andriono, Takim (1989)

    Doctoral thesis
    University of Canterbury Library

    The Base Isolation technique and its benefits in reducing the transmitted earthquake energy into a structure has gained increasing recognition during the last two decades. This recognition is indicated by the application of Base Isolation systems to a large number of bridges, several multistorey buildings and some power plants in countries which have high seismic risk. Unfortunately, the currently available design procedures, especially for multistorey structures, seem inadequate and too restrictive and as a result present practice still relies upon a series of deterministic time history analyses which are not only impractical for design purposes but appear unable to give the designer a clear insight into the seismic behaviour of the multistory structure. This research is carried out to investigate in more detail the effects of various structural parameters and ground motion characteristics on the seismic response of Base Isolated multistorey structures. It also reviews the shortcomings of the current design methods. The results are then used to develop two simplified analysis methods for practical design. The first method which is called the Code-Type approach can be used to accurately estimate the inertia forces, not only at the level of the isolation devices but throughout the height of the multistorey structure. It is recommended for use as a preliminary design tool or even a final design tool for simple Base Isolated multistorey structures. The second procedure which is based on the Component Mode Synthesis method is suggested for final design purposes of more complex Base Isolated multistorey structures. This method enables the designer to evaluate the effects of the isolation devices on the contribution of each mode of vibration to the total response of the structure.

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  • Blind deconvolution and phase retrieval

    Lane, Richard George (1988)

    Doctoral thesis
    University of Canterbury Library

    Theoretical and practical aspects of identifying and deconvolving a convolution in more than one-dimension are presented. In contrast to conventional techniques which require knowledge of the blurring function, this thesis describes techniques for "blind" deconvolution. The techniques introduced differ from previous work in the field of blind deconvolution because they do not require an ensemble of similarly blurred images, i.e. they can be effectively employed upon a single convolution. The first method for blind deconvolution introduced relies on the analytic properties of the Fourier spectrum of a compact image. Rather than deal with continuous images, a discrete approximation is employed. It is argued, however, that approximation of the Fourier spectrum by a finite order polynomial model is a logical response to the practical constraints posed by limited a.mounts of noisy data. Since the convolution of two images is equivalent to a multiplication of their Fourier spectra, deconvolution is consequently equivalent to factorisation of their Fourier spectra. In one dimension it is always possible to factorise a polynomial, even when it is of infinite order. These factors correspond to isolated points, in the complex plane into which the Fourier spectra are analytically continued, where the spectra are zero. Since these points are distinct there are a large number of factors and hence there is usually a large number of ways of deconvolving a one-dimensional image. By contrast the analytically continued Fourier spectrum of a two-dimensional image exists in a four-dimensional space and is zero on a two-dimensional analytic surface, here called a zero-sheet. Because of the analytic nature of the zero-sheet it is not possible, in general, to factorise a two-dimensional spectrum or equivalently partition its zerosheet into separate analytic surfaces. The major exception is when the true image is a convolution in which case the zero-sheet is, in fact, the union of the zero-sheets of the components of the convolution. As a result the zero-sheet of a convolution can be partitioned into two zero-sheets which can be used to recover, to within a complex constant, the components of the convolution. The addition of noise is shown to link the zero-sheets of the components of the convolution. Consequently it is no longer possible to partition the zero-sheet without isolating and correcting these "bridges" between the zero-sheets of the components. The Fourier phase problem forms a special subclass of the blind deconvolution problem, one in which the true image and the blurring function are conjugate mirror images of each other. The data in the Fourier phase problem comprises the oversampled magnitude of the Fourier transform of the true image. Consequently, it is necessary to reconstruct the Fourier phase before an estimate of the true image can be formed. It is shown that a solution exists and the accuracy of the solution can be empirically related to the amount of noise present in the Fourier magnitude data. It is shown that a unique solution to the Fourier phase problem in more than one dimension exists except when the spectrum is the Fourier transform of a convolution. In this case, the number of solutions to the Fourier phase problem is related to the number of component images which have been convolved to produce the convolution. The second technique for deconvolution introduced in this thesis uses these multiple solutions to the Fourier phase problem to recover information about the phase of the spectra of the components of the convolution. The Fourier phase is, however, only recovered modulo π. The problems encountered in the modified magnitude problem, as it is called in this thesis, are analysed and techniques for overcoming these difficulties are described. A final result presented herein is an extension to an existing technique for blind deconvolution of ensembles of two-dimensional speckle images. It is shown that comparing the zero-sheets of the speckle spectra leads to a useful new approach to speckle imaging.

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  • An examination of selected novels by Graham Greene : with reference to the Teilhardian concept of the world and salvation

    Clark, Anthony Raymond (1980)

    Masters thesis
    University of Canterbury Library

    In this thesis I have applied some of Teilhard de Chardin's concepts about the world, man and salvation to selected works by Graham Greene. Having found strong similarities between the subject matter and attitudes of the two writers, I believe that the comparison helps to demonstrate more clearly a systematic unity of theme and purpose in those novels I have selected, as well as offering some new insights into Greene's doctrine. I have made use of selected writings by Teilhard, in particular Le Milieu Divin and The Phenomenon of Man, as well as critical writings on these and his other works. Besides various critical writings on Greene and his works' I have selected for particular study the following novels: It's a Battlefield, Brighton Rock, The Power and the Glory; The Heart of the Matter and The End of the Affair. In Chapter 1, I examine the interest of both writers in Peguy and compare Teilhard's main ideas on the world and salvation with the way these matters are dealt with by Greene in general. The remaining 6 chapters deal with the five novels individually and provide a summary and conclusion. While the question of any positive influence of Teilhard's writings on Greene's own work is at present difficult to establish with certainty, there is such similarity between the concepts of Teilhard on the one hand and their fictional presentation in Greene's work on the other, that a more than coincidental link is suggested.

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  • Hari Hari : a study of land use and a community

    Maturin, Susan E. (1981)

    Masters thesis
    University of Canterbury Library

    A multi-disciplinary approach was used to study land use, and the associated community of Hari Hari. Land use decisions concerning forestry and agriculture, were placed in the context of social and economic needs of the human system and ecological requirements of the natural system. Data was collected from interviews with 17% of the Hari Hari community. The needs of the community were identified, from a detailed study of the Hari Hari people. Past and present land uses were studied in detail to determine the suitability of each land use, and its ability to work within the constraints imposed by the natural system. Future land use options and their social, economic and ecological implications were outlined. The most appropriate options were selected, according to their ability to satisfy the needs of the community, and ecological requirements of the natural systems. Appropriate options for agriculture included the following: a. continuing as at present; and, b. increasing farm management efficiency; and, c. diversification into opossum and deer farming. These options met ecological requirements and would contribute to community needs. The most appropriate option for forestry was found to be; immediate cessation of production logging until the natural constraints are identified and a logging system which works within these constraints is identified. This option conflicts with the social need to maintain employment. However the study found that closure of the sawmill would have little impact upon the Hari Hari community, other than a reduction in employment. Possible options for establishing alternative employment activities were suggested. These included a fur industry, an out-door pursuits centre, cottage industries, and ventures which would promote community self-sufficiency. As a whole, this study emphasised the value of a multi-disciplinary approach to land use planning.

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  • The mineralogy, geochemistry and origin of Lower Tertiary smectite-mudstones, East Coast deformed belt, New Zealand.

    Fergusson, Linda Jan (1985)

    Masters thesis
    University of Canterbury Library

    Marine smectite-mudstones of Lower Tertiary age (Teurian to Runangan) occur throughout the East Coast Deformed Belt of New Zealand. In Marlborough, Marl lithofacies of the Amuri Limestone comprise calcareous, siliceous smectite-mudstone alternating with biomicrite. In Wairarapa, the Kandahar Formation consists of calcareous smectite-mudstone, micritic limestone beds and mass-flow greensand beds. Calcareous smectite-mudstone is also a minor interbedded lithology in the Mungaroa Limestone of Wairarapa. The Wanstead Formation in Hawkes Bay comprises uncemented smectite-mudstone with interbedded mass-flow greensands. Lower Tertiary sequences throughout the East Coast Deformed Belt are typically disrupted by thrust faults and associated shear/mélange zones which have developed in the weak smectite-mudstone lithology. Insoluble clay fractions of the smectite-mudstones are composed of well crystallised smectite + illite ± quartz (chert). Both the smectite and illite clays are discrete phases with no interstratification suggestive of post-sedimentary transformation of smectite to illite. From detailed phase analysis, the smectite clay overall is a montmorillonitic species, but with varying interstratification of other dioctahedral smectite species and varying layer charge. No distinct stratigraphic trends in clay fraction mineralogy or smectite mineralogy are apparent. Sand fractions of the mudstones are dominated by authigenic or non-volcanic detrital minerals. Average smectite + illite structural formulas calculated from chemical analyses are commonly non-ideal, with deficiencies in aluminium particularly apparent. The dominant exchangeable cations are calcium in Marlborough mudstones and sodium in Hawkes Bay mudstones. Trace element geochemistry of the smectite-mudstones is similar to that of typical shale and carbonate rocks. Variations in trace element abundances·reflect the lithological character of the mudstones and do not appear to be a useful tool for regional stratigraphic correlation. Combined sedimentological, mineralogical and geochemical features of the smectite-mudstones indicate a non-volcanic origin. They did not form by in-situ alteration of ash-falls and are unlikely to have formed from transported/reworked ash. Previous use of the term 'bentonite' for the smectite-mudstones implies such a mode of genesis and should be discontinued. Hemipelagic sedimentation and/or mass-flow redeposition of detrital or neoformed clay in an open oceanic, relatively deep water environment is proposed as the origin of the smectite-mudstones.

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  • An evaluation of the validity of multidimensional scaling methods : for the representation of cognitive processes

    Fraser, Christopher O (1980)

    Doctoral thesis
    University of Canterbury Library

    This study is an evaluation of the issues involved in providing a meaningful psychological interpretation of multidimensional scaling solutions, for example to regard them as valid representations of the cognitive processes involved in generating the data. The various metatheoretic approaches that have been developed to define appropriate procedures for the quantification of psychological attributes are discussed and evaluated. It is argued that much current psychological research is based on an inappropriate paradigm. In particular it is argued that the emphasis on magnitude estimation to generate psychological data is misplaced and scales derived from weak-ordered judgements are much to be preferred. Extending these arguments to the multidimensional case, it is argued that most applications of multivariate methods in psychology have shown insufficient recognition of the theoretical implications of using a particular technique. The application of any method of data analysis such as multidimensional scaling is only appropriate if it can be shown that the assumptions implicit in the scaling model are satisfied for that set of empirical data. In addition some variations in the scaling model, such as subjective metrics scaling, involve additional assumptions which need to be explicitly formulated and tested. These metatheoretic limitations, as well as evidence on the frequent occurrence of violations of its basic assumptions suggest that multidimensional scaling configurations can at best be attributed with only a limited degree of psychological significance. It is suggested that such value as it does possess is limited to the evaluation of non-dimensional structural hypotheses derived from some prior substantive theory. An empirical example is presented demonstrating that even when there appears an obvious and intuitive interpretation of the dimensions of a MDS configuration, the solution may be completely inappropriate as a model of the underlying cognitive processes. A second example however describes a more appropriate and successful application of multidimensional scaling methodology. A theoretical interpretation of emotion labelling based on Guttmans (1957 ) facet theory, was shown to be substantially confirmed in the structure of a MDS configuration.

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  • Regulation of microbial production in intertidal mudflats : the role of Amphibola crenata, a deposit feeding gastropod

    Juniper, S.K. (1982)

    Doctoral thesis
    University of Canterbury Library

    Interactions between the deposit feeding gastropod Amphibola crenata and the microbial community in intertidal mudflats were studied in laboratory and field experiments in two New Zealand estuaries. The study was mainly designed to reveal the effect of deposit feeding on bacterial and microalgal production and assess the importance of these microorganisms to the nutrition of the snail. The secondary aim was to compare the influence of Amphibola to external factors which regulate microbial production on the mudflat. Short-term effects of deposit feeding on bacterial production were examined by monitoring the recolonisation of Amphibola faeces by bacteria. Long-term effects on bacterial production were studied in artificial enclosures in the field where the effect of snail density on bacterial numbers and activity was monitored. These same enclosures were also used to study the effect of grazing by the snail on standing crop and productivity of the epibenthic algae. Assimilation of bacterial carborn by Amphibola was experimentally measured, and the contribution of bacterial and microalgal carbon to the snail’s carbon budget was estimated. The effect of microbial biomass on the feeding behaviour of Amphibola was also examined. It was found that a pulse in bacterial production occured during the recolonisation of Amphibola faeces by bacteria. This appeared to be similar in magnitude to the amount of bacterial biomass consumed by the snail - approximately 4. 5 mg C/m²/day. Amphibola also had a minor long-term influence on bacterial numbers and activity, but no clear effect on productivity was apparent. Grazing by Amphibola caused a substantial reduction in microalgal standing crop and productivity and affected the species composition of the microalgal community. Both the bacteria and microalgae serve as significant sources of carbon for the snail, but a large additional input of carbon is required to meet its nutritional needs. Other possible sources of carbon for the snail include meiofauna and non-living organic material. Amphibola was also found to alter its feeding rate in response to changes in microbial biomass, in a manner which may improve the return for feeding effort. In overview, it appears that Amphibola and the sediment bacteria similarly influence the other 's productivity while Amphibola has a greater effect on the microalgae than the microalgae have on Amphibola. Ultimate control of microbial productivity was concluded to be external to these relationships, with the snail acting only to modify seasonally determined levels of productivity.

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  • Phase manipulation of speech using FIR digital filters

    Stephen, R. D. C. (1987)

    Doctoral thesis
    University of Canterbury Library

    Three related investigations involving the fields of FIR digital filters, phase manipulation of speech, and speech coding via bandwidth compression are reported. The first investigation is aimed at providing a means of generating the impulse response coefficients of a non-linear phase FIR digital filter. Existing methods of designing linear-phase filters are discussed and compared from a defined common comparison base. The methods available for designing non-linear phase filters are examined. An existing linear phase design method is extended to the non-linear phase case and shown to be useful. The required impulse response length in the presence of non-linear phase is studied. Particular emphasis is placed on "random phase" filters and their generation because they are required by the second investigation. The second investigation examines in detail the ramifications of phase randomising a speech signal. The analytic zero representation of speech which forms the underlying base on which the discussion, and answers, are based is elucidated. The technique of using a non-linear phase FIR filter is shown to be feasible and as a minimum, offers at least the same level of performance as a very early reported technique. Significant differences in the behaviour of male and female speech is demonstrated. The third and final investigation reports some early and incomplete experiments on a radically different approach to achieving band width compression and expansion of a signal. The technique is referred to as "phase unwrapping". It is based on the application of a linear phase FIR digital filter in an adaptation of the traditional convolution relation. The motivation and validity of the basic idea is outlined and justified via application of the procedure to simple sinusoids and one experiment using real speech. The fundamental problem to be overcome is identified and the basis of a possible means of solution indicated.

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  • Ashmon : a monitoring package for prime 50 series machines

    Ashton, Paul (1984)

    Discussion / Working Papers
    University of Canterbury Library

    A major objective for all interactive systems is to provide adequate response time performance for terminal users. The best way to find the causes of inadequate response is to examine the behaviour of the components of response time plotted against workload. (Examples of components are : time running or waiting for the CPU, and time spent waiting for IO transfers). This report describes the development of ASHMON, a monitoring package designed to produce such plots for Prime 50 series computers. In addition to software performance monitors, the package includes data interpretation programs which produce performance summaries and plots, a program which combines data from a number of monitoring sessions, and a program to configure the package on any Prime 50 series machine (apart from the P850). The report also includes discussion of experiments done to validate measurements obtained by the monitors.

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  • A digital logic simulator for the Apple Macintosh

    Wild, Michael (1985)

    Discussion / Working Papers
    University of Canterbury Library

    The aim of this project was to design a digital logic simulator to run on the Apple Macintosh. It was envisaged that users would be able to design a network of gates, flip-flops and signal sources interactively, then simulate the operation of the circuit. If the circuit did not behave as expected, it could be changed and a simulation run on the updated circuit.

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  • A Simulation Model to study the performance of the HDLC protocol.

    McAuley, Bruce J. (1984)

    Discussion / Working Papers
    University of Canterbury Library

    The aim of this project was to produce a Simula program that will model the ISO HDLC Asynchronous Balanced Mode (ABM) protocol. This program can be used firstly to provide a tool for performance evaluation of the HDLC controlled data links and secondly, to provide more insight into how the various parameters of an HDLC implementation and the data channel characteristics influence the performance.

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