935 results for 2000

  • Inverse problems in astronomical imaging

    Johnston, Rachel Anne (2000)

    Doctoral thesis
    University of Canterbury Library

    The imaging of astronomical objects is limited by atmospheric turbulence, which consists of layers of varying refractive index surrounding the earth. These refractive index fluctuations are a direct consequence of the warming and cooling of air and water vapour in the atmosphere. Wavefronts entering the atmosphere acquire phase distortions, which when propagated result in amplitude fluctuations known as scintillation. Hence the practical manifestation of the atmosphere is a degradation of the signals passing through it, for example it severely limits the resolution of images captured by ground-based telescopes. A variety of solutions, or inverse problems, have been proposed and trialed in the attempt to obtain the best possible images from astronomical telescopes. An orbiting telescope (for example the Hubble space telescope) is one solution. In this case light is captured before it is distorted by the atmosphere. Less expensive ground-based solutions include the post processing of short exposure images and real-time compensation using adaptive optics, both of which are investigated in this thesis. However, the success of an inverse problem lies in the accurate modelling of the processes that give rise to the corresponding forward problem, in this case the random refractive index fluctuations that characterise the atmosphere. Numerical simulation of atmospheric turbulence is achieved using phase screens in which the assumption of Kolmogorov statistics is often made. A previously presented method for modelling Kolmogorov phase fluctuations over a finite aperture, the midpoint displacement method, is both formalised and improved. This enables the accurate generation of atmospheric speckle images for the development and testing of post processing methods. Another aspect of the forward problem is the accurate simulation of scintillation, resulting from the propagation of phase distorted wavefronts. Commonly used simulation methods achieve this by assuming periodic boundary conditions. A technique for the accurate modelling and simulation of scintillation from an aperiodic Kolmogorov phase screen is presented. The more physically justifiable assumption of smoothness is shown to result in a propagation kernel of finite extent. This allows the phase screen dimensions for an accurate simulation to be determined and truncation can then be used to eliminate the unwanted spectral leakage and diffraction effects usually inherent in the use of finite apertures. Deconvolution methods are popular for the post processing of atmospheric speckle images to compensate for the effects of the atmosphere. Conventional deconvolution algorithms are applied when the distortion is known or well-characterised, whereas, blind deconvolution algorithms are used when the distortion is unknown. Conventional deconvolution techniques are not often directly applied to astronomical imaging problems as the distortion introduced by the atmosphere is unknown. However, their extension to blind deconvolution is straightforward and hence their development is valuable. The ill-conditioning of the deconvolution problem requires the addition of prior information, such as positivity, to enable its solution. It is shown that the conventional deconvolution problem can be reformulated as an equivalent quadratic programming problem. Consequently, an accelerated quadratic programming approach is applied and shown to be an improvement to an existing method used for enforcing positivity in deconvolution applications. The main algorithmic differences of the new method are implementation via the fast Fourier transform (FFT) and guaranteed convergence to the constrained minimum. Blind deconvolution is also an interesting problem that may arise in many fields of research. It is of particular relevance to imaging through turbulence where the point spread function can only be modelled statistically, and direct measurement may be difficult. The extension of the quadratic programming method to blind deconvolution, combined with Tikhonov-Miller regularisation (energy constraints), smoothness constraints, penalty terms and statistical priors produced a series of new algorithms. The performance of these algorithms is illustrated on simulated astronomical speckle images. Ground-based adaptive optics (AO) technologies are an alternative to post processing methods and aim to compensate for the distortion introduced by the atmosphere in real-time. Knowledge of the vertical structure of the atmosphere combined with AO provides the potential for compensation over a wide field of view. However, the continually changing nature of atmospheric turbulence places strict requirements on techniques for determining the turbulence structure. The remote sensing of scintillation data to estimate this information is known as scintillation detection and ranging (SCIDAR). Application of SCIDAR methods to the capture and analysis of experimental data, as demonstrated in this thesis, highlighted a number of problems with the technique. Methods for overcoming these difficulties are discussed and demonstrated. Finally, alternative approaches to the estimation of atmospheric turbulence profiles and a proposed new technique are investigated.

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  • "Have-nets and have-nots" - what determines internet access in New Zealand

    Smythe, M. (2000)

    Conference item
    Christchurch Polytechnic Institute of Technology, Te Wānanga Ōtautahi

    Internet access and social issues: Various commentators overseas have speculated that access to the Internet is a dynamic force for social good, improving communication, education, employment, medical care, and political participation. This has come about due largely to the opportunities the Internet and other technologies seemingly represent to empower individuals. In addition there is an increasing amount of information becoming available only on the Internet. Consequently, issues of access to Information Technology and the Internet are becoming of increasing concern to policy-makers both in NZ and overseas, where terms such as “digital divide” and “information haves and have-nots” are appearing regularly in various media. At a recent Unesco conference is was stated that “Unesco could use its mandate of promoting access to information ...to define a universal right of access to the Internet with which member states would have to comply”(Pullar-Strecker, 1998).

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  • 80% of what? - a preliminary investigation of tutors' understanding of the 80% pass mark for DipBC modules

    Kennedy, D.; Ross, J. (2000)

    Conference item
    Christchurch Polytechnic Institute of Technology, Te Wānanga Ōtautahi

    “I don’t take an awful lot of notice of the 80% thing” Tutor comment. As new people are recruited to join the many teams of NDBC teaching staff throughout the country, “old timers” attempt to explain the concept of mastery that is supposed to form the basis of assessment procedures in the various modules. The concept is described in the NZQA approved document, commonly known as the Bluebook, which details the NDBC, and other, qualification requirements. In that document, a figure of 80% is suggested as a guideline pass mark for assessments which concern knowledge-based modules. This paper focuses on the meaning of that 80% guideline since, for many, both the explanation and the practice of assessing mastery provide a hurdle with an element of mystery. We attempt to unravel some of the mystery by examining what the current practice is in one Polytechnic and to suggest that our methods may be forcing a dumbing down of assessments which target the comprehension sections of modules. The descriptors for the diploma modules categorise the learning required for each module using the RCAP model. It seems that even with Recall sections some tutors have trouble relating the 80% to the assessment. The Application and Problem Solving areas have largely become the things we assess using assignments. This paper examines how the 80% pass mark is being applied to assignments and to the comprehension elements of various courses, for it is in these areas of cognitive processing that competency (or 80%of competency) is harder to establish particularly in areas of original, creative thought. The paper raises the question of honesty of assessment practices in terms of marking guides and suggests that we should be insisting on using both appropriate tools for generating valid evidence and appropriate means of judging student performance against a course’s learning outcomes, rather than trying to force pass marks to add up to 80%.

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  • Database design and the reality of normalisation

    Kennedy, D. (2000)

    Conference item
    Christchurch Polytechnic Institute of Technology, Te Wānanga Ōtautahi

    What is normalisation all about? Why do we teach it? How do we teach it? How can we explain normalisation to our students so that they will understand it? This paper presents a method of teaching normalisation that, experience has shown, students can understand. The paper also considers the broader questions of: ¨ Why is normalisation important? ¨ Where does it fit in the process of database design? ¨ How important is it in the “real world”? Database design can be done using an entity relationship diagram (ERD) - a top down approach or by normalisation of sets of data - a bottom up approach The question is, What do real database designers do? ¨ What methodologies do they use? ¨ How important is normalisation? ¨ What normalisation rules do they use i.e. how far do they take it? ¨ How important is denormalisation? This paper presents a summary of findings, from interviews with database designers, that should help us in our teaching of Database design.

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  • Aptitude testing as a predictor of success: the Christchurch experience

    Ross, J. (2000)

    Conference item
    Christchurch Polytechnic Institute of Technology, Te Wānanga Ōtautahi

    Christchurch Polytechnic has used an aptitude test to aid selection of students since 1975 and its usefulness as a predictor of success has been informally debated regularly since that time. In recent years, it has been used to assist in the selection process but achievement of a poor test result has not necessarily been used to exclude a student from beginning study. This paper examines the results of aptitude tests over a period of three years, and the subsequent performance of those students who joined the Certificate in Business Computing (CBC) programme for full-time study. Aptitude Test results are examined by section (pattern matching, mathematical reasoning, logic, words) in an attempt to find out if any one section provides a better indicator of success than the rest. The measure of success used is based on achievement of passes in the nine modules undertaken by new CBC students in their first semester of study. Trends which are observed in this analysis suggest that at the Pass mark which has been used so far, the test does not give a valid indication of success or otherwise. Whether or not a student succeeds in their first semester is not significantly dependent on whether or not they Passed the Aptitude Test. When a higher pass mark is considered, then there is a small level of correlation between achievement of that mark in the test and subsequent success in CBC study. Results in the logic section of the test provide the best indicator but the figures show that many students who did not score well in that section were still able to succeed in their study. The ability to predict success or otherwise in CBC study by using scores achieved in the Aptitude Test as a critical indicator remains inconclusive.

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  • Workplace assessment: balancing the needs of student and organisation

    Wieck, M (2000)

    Conference item
    Christchurch Polytechnic Institute of Technology, Te Wānanga Ōtautahi

    This paper compares the needs of the student and employer as they undertook a cooperative education project, completed during the last six months of a fulltime, three-year degree in business computing. Some apparent conflicts of interest were examined and ways to resolve these conflicts were explored using Alexander’s patterns framework. The study derives from experiences with the first two cohorts of the Bachelor of Business Computing (BBComp) at Christchurch Polytechnic, where students apply the knowledge and skills gained on the course to real challenges and opportunities presented to them by companies in a business computing environment. The respective outcomes are negotiated between student and employer before the project begins. The student must in addition meet the academic requirements of the Polytechnic; they submit a number of assessments both during and after the project’s completion. The employer’s focus is on producing a commercial product subject to typical constraints such as budget, quality and time. Conflict may arise when - despite the agreed outcomes - the exigencies of the commercial environment force changes upon the student, deflecting them from their original intent. The author has responsibility for the coordination of the student project and acts as arbiter for both parties.

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  • The politics of privatizing water services : in theory and practice.

    Treliving, Victoria (2000)

    Masters thesis
    University of Canterbury Library

    Since the early 1980s, the phenomenon of privatization has quickly spread worldwide, changing the balance between the state and the market in favour of the latter. Its adoption questions and replaces the traditional roie of the state in providing and controlling certain public services. One formerly predominantly public service to be affected by privatization is piped water services, as it is commonly argued that private suppliers stimulate greater efficiencies and innovations than public suppliers. Most of those writing on this subject tend to focus narrowly on comparisons of public and private water companies in an attempt to argue that one or the other is best. Alternatively, some concentrate on the policy process through which privatization found favour. However, the thesis takes a very different approach to the analysis of privatizing water supplies, contributing to an area that has attracted little attention: its theoretical context and its implications for democratic politics. The aim of the thesis is to concentrate on, and extend, the types of assumptions - efficiency and innovation - inherent in arguments for privatization, thus providing a wide-ranging theoretical context in which to locate the privatization of water services. After discussing at some length exactly what comprises privatization, the thesis examines the theoretical foundations from which the policy originates. With reference to two case studies of privatization - Britain and Wales, which privatized water services in 1989, and New Zealand, which has not fully privatized its water, but is increasingly favouring more commercial practices - the thesis then illustrates how the theories have informed privatization in practice. The thesis concludes that privatizing water supplies . is an inappropriate extension of these theories because, first, they do not recognize the inherently non-commercial nature of water services and, second, because their implications for citizenship, and therefore democratic politics, are potentially very damaging.

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  • Privacy and the Internet : how to rescue the fly from the tangled web?

    Alderdice, Joanna. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Efficacy of the Broadcasting Standards Authority in determining privacy complaints

    Baber, Catherine Hannah. (2000)

    Scholarly text
    Victoria University of Wellington

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  • The Press Council : is it an effective control on New Zealand print media

    Basile, Janine Alexandria. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Information meetings : a perspective for New Zealand : a study on the New Zealand Family Court, children and their adaptation to family changes

    Auerbach, Ines. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Archives, copyright and film : an analysis of copyright for film archives

    Burton, Warwick. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Ratification under the Companies Act 1993 : an analysis of section 177 of the Companies Act 1993 with reference to the ratification of breaches of directors' duties

    Murray, Brian, 1948- (2000)

    Scholarly text
    Victoria University of Wellington

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  • Unilateral misuse of market power : Section 36 of the Commerce Act 1986

    Horan, John K. (2000)

    Scholarly text
    Victoria University of Wellington

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  • The good faith concept in the Employment Relations Act 2000 : possible effects on the individual employment relationship

    Oberwinter, Jens Wilhelm. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Cyberporn : investigatory and prosecutorial issues relating to child pornography in the New Zealand context

    Jefferson, Judith. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Immigration policy and the children born to illegal immigrants : do they stay or do they go?

    Walker, Rachael. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Big gains from small claims : the patentability of expressed sequence tags

    Des Tombe, Michael. (2000)

    Scholarly text
    Victoria University of Wellington

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  • The search for principle : the government's liability in negligence for the careless exercise of its statutory powers

    Geuther, Thomas. (2000)

    Scholarly text
    Victoria University of Wellington

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  • Civil liability for prospectus misstatements : should the Fair Trading Act apply?

    Giles, Brendon Daniel. (2000)

    Scholarly text
    Victoria University of Wellington

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