82,937 results

  • Ecological development of constructed wetlands built for treating mine tailings water at Tara Mines, Ireland

    O'Sullivan, A.D.; Murray, D.A.; Otte, M.L. (2003)

    Conference Contributions - Published
    University of Canterbury Library

    Mine associated wastewater is characteristically elevated in metals and other contaminants and has been conventionally treated with costly chemical applications. The development of passive treatment systems such as wetlands, which employ both biotic and abiotic processes, has been recognized as an economically feasible, ecologically acceptable treatment technology in the last decade. Not only can constructed wetlands provide an efficient facility for treating wastewater, they can also offer ancillary benefits such as ecological niches and therefore be of educational and often recreational value to society as well. Two experimental-scale treatment wetlands were constructed at an active lead/zinc mine near Navan, Ireland in 1997 to treat water enriched with sulfate and metals. Each system comprised three 12 m2 (2 m depth) in-series surface-flow cells viz., inflow, vegetated and outflow. Sulfate-reducing bacteria were indigenous in the anaerobic spent mushroom substrate used, where biological reduction of sulfate to sulfide occurred. Sulfide subsequently precipitated with metals from the water. The treatment efficiency of the wetlands was promising with concentrations of sulfate (up to 29 g m-2 day -1 (69%)), lead (6.6 mg m-2 day -1 (64%)) and zinc (70 mg m-2 day -1 (98%)) successfully removed from the wastewater. The ecological functioning of these constructed wetlands was also demonstrated with food webs, nesting niches and refuge sites afforded by colonizing communities of macroinvertebrates, macrophytes, microorganisms and other visiting wildlife. By 15 months following construction of the treatment wetlands, 30 species of macroinvertebrates were identified in system 1 and 21 species in system 2, while 3 plant species, 3 algae species and 1 moss had also colonized the ecosystems. Sulfate reducing bacteria genera included Desulfotomaculum, Desulfovibrio, Desulfococcus and Desulfobulbus. Annual dieback of planted species Typha latifolia and Phragmites australis contributed substantial amounts of biomass to the ecosystems, which led to a renewal of the carbon supply that drove the biologically mediated treatment process. It is speculated that the ecological diversity of the wetlands contributed to their treatment success based on inherent ecosystem complexity.

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  • Constructed Wetlands for Treating Processed Mine Water - an Irish Case Study

    O'Sullivan, A.D.; Murray, D.A.; Otte, M.L. (2003)

    Conference Contributions - Published
    University of Canterbury Library

    Mine wastewater is characteristically elevated in metals and sulfate and conventionally treated with costly chemical applications. The development of passive treatment systems, employing both biotic and abiotic processes, has been recognized as an economically feasible, ecologically acceptable technology in the last decade. However, to-date most of these passive systems have been applied to abandoned mine waters for the primary purpose of increasing pH and removing metals. Two experimental-scale treatment wetlands were constructed and monitored at an active lead/zinc mine (Tara Mines) in Ireland, to treat alkaline mine seepage with elevated sulfate (and also metal) levels. Each system comprised three 12 m² (2 m depth) in-series surface-flow cells viz., inflow, vegetated and outflow and contained spent mushroom substrate (SMS). Typical aqueous concentrations of 830 mg L⁻¹ sulfate, 0.15 mg L⁻¹ lead and 2.0 mg L⁻¹ zinc entered the treatment wetlands at a flow rate of c. 650 mL min⁻¹. Anaerobic substrates, in which sulfate-reducing bacteria were indigenous, were conducive to biological reduction of sulfate to sulfide. Sulfide subsequently precipitated with metal cations. Monitoring of these wetlands over a 2-year period showed successful (maximum) removal of sulfate (29 g m⁻² day ⁻¹ (69%)), lead (6.6 mg m⁻² day ⁻¹ (64%)), and zinc (70 mg m⁻² day ⁻¹ (98%)). These contaminants were somewhat associated with the vegetation roots but more significantly so with the substrates. The interacting processes within the wetland ecosystems responsible for decontamination of the wastewater are currently being elucidated and quantified using a systems dynamic model. The communities of colonizing macroinvertebrates, macrophytes, algae and microorganisms also contributed to development of diverse ecosystems and a successful alternative treatment process.

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  • Iron oxidation in net alkaline C02-rich mine waters

    Nairn, R.W.; O'Sullivan, A.D.; Coffey, J. (2002)

    Conference Contributions - Published
    University of Canterbury Library

    Iron oxidation and hydrolysis were examined in net alkaline mine waters exiting abandoned underground lead and zinc mines. It was hypothesized that degassing of excess CO2 would result in increased pH, and thus positively influence rates of iron oxidation, despite subsequent proton production during hydrolysis. It was also hypothesized that the addition of iron oxide solids would positively influence iron removal rates. The relative roles of CO2 degassing and iron solids additions were evaluated in a field microcosm experiment in June 2001. Five treatments were established in triplicate (closed, open, open + Fe, open + aeration, open + aeration + Fe). After 36 hours, greatest water quality changes were found in the open + aeration + Fe treatment. Dissolved oxygen was greater than 7.5 mg/L and pH was greater than 7.7, while alkalinity and Fe decreased to 52 and 0.81 mg/L, respectively. In non-aerated treatments, dissolved oxygen was less than 1.6 mg/L and pH was less than 6.2. Alkalinity decreased in all aerated treatments to less than 70 mg/L, but remained greater than 200 mg/L in all other treatments. Iron concentrations remained greater than 70 mg/L in non-aerated treatments. Aeration and the active degassing of excess CO2, coupled with the presence of iron oxide solids, resulted in the greatest changes in water quality.

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  • Bioremediation of alkaline mine effluent using treatment wetlands

    O'Sullivan, A.D.; Murray, A.D.; Otte, M.L. (2001)

    Conference Contributions - Published
    University of Canterbury Library

    Decommissioning of metal mine effluent traditionally involved costly chemical applications. Development of passive treatment systems, employing both biotic and abiotic components has been recognized as a cost-effective, ecologically favorable approach in the last decade. This paper documents construction of the first (experimental) treatment system in Ireland at a large lead-zinc mine, attempting to promote adoption of this innovative treatment alternative for future applications.

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  • Rehabilitating mine tailings water using constructed wetlands

    O'Sullivan, A.D.; Murray, D.A.; Otte, M. (2000)

    Conference Contributions - Published
    University of Canterbury Library

    Outukumpu Zinc-Tara Mines Ireland, located approximately 50 km north of Dublin, is Europe's largest producer of lead and zinc ores. Water used during extraction and purification of these ores is enriched with sulfate and heavy metals. Presently, this water together with suspended tailings, is pumped from the mine and stored in a large tailings settling pond. Two experimental artificial wetlands were built beside this settling pond to treat seepage. The primary strategy employed for treatment of the water is the reduction of sulfate to sulfide. The wetlands are maintained anaerobic to provide optimum conditions conducive to reduction reactions. This process is mediated by sulfate reducing bacteria, which are indigenous in the bedding substrate (spent mushroom compost) used. The alkaline nature of the mine tailings water (due to the strong buffering capacity of the prevailing limestone geology) facilitates the subsequent precipitation of metal sulfide complexes which form following reduction of sulfate. The constructed wetlands have been in operation for two years but have exhibited consistent removal of sulfate from water. Recent results suggest that algae, having spontaneously invaded the wetland ecosystems, also play a substantial role in the removal of heavy metals from the tailings water. To-date, this decontamination approach is showing to be efficacious and cost-effective.

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  • A Framework for Web-based E-Learning of Discrete Event Simulation Concepts

    Page, B.; Kreutzer, W. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper describes selected e-learning materials developed as part of a cooperative simulationsupported learning initiative for university courses on discrete event simulation. These materials include Java applets for teaching general simulation concepts, as well as a web tutorial and an Internet-hosted simulation laboratory which teaches how to use a simulation framework in Java.

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  • FluidStream 7.0 – User’s Guide

    Nokes, R. (2007)

    Authored Books
    University of Canterbury Library

    User Guide for FluidStream, a particle tracking velocimetry (PTV) system that processes digital images and produces two dimensional velocity fields.

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  • A stylized cartoon hair renderer

    Shin, J.; Haller, M.; Mukundan, R. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    This paper describes a new hair rendering technique for Anime characters. The overall goal is to improve current cel shaders by introducing a new hair model and hair shader. The hair renderer is based on a painterly rendering algorithm which uses a large amount of particles. The hair model is rendered twice: first for generating the silhouettes and second for shading the hair strands. In addition we also describe a modified technique for specular highlighting. Most of the rendering steps (except the specular highlighting) are performed on the GPU and take advantage of recent graphics hardware. However, since the number of particles determines the quality of the hair shader, a large number of particles is used which reduces the performance accordingly.

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  • Constructed wetlands for treatment of mine tailings at Tara Mines, Ireland

    O'Sullivan, A.D.; Murray, D.A.; Otte, M.L. (2000)

    Conference Contributions - Published
    University of Canterbury Library

    Natural and constructed wetlands can filter pollutants from water. Recently this property has been exploited in utilising wetlands for passive water treatment. Using relatively concentrated waste, wetlands have been shown to be effective in retaining in excess of 90% metals (MAY et al. 1993) and over 70% sulphate (WINTER & KICKUTH 1989). This approach to water quality improvement is more favourable than traditional treatment methods requiring intensive chemical and labour inputs. Experimental wetlands have been constructed on site at Tara Mines, County Meath, Ireland to facilitate a research project investi- gating the capacity of filter systems in retaining sulphate and metals from mine tailings water. It is expected that such systems, based on natural processes, will be efficient yet require little maintenance and will, therefore, be economically attractive.

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  • Biochip Multi-function Signal Generator

    Moore, C.P.; Blaikie, R.J.; Muys, J.J. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    The University of Canterbury recently developed a biochip, or “lab-on-a-chip” platform, which is used for the diagnosis and fast analysis of biological samples [1]. The biochip uses dielectrophoresis (DEP) to manipulate cells and other small particles [2]; this requires a.c. waveforms with well-defined frequency and amplitude. Hence, a dual-channel signal generator, capable of generating sine, square and triangle waveforms at frequencies up to 20 MHz and amplitudes up to 20 Vpp, was designed and built. A series of experiments using the signal generator and biochip demonstrated the effects of positive and negative DEP on polystyrene beads.

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  • Two Cultures - Joint Success

    Lawrence, J.; Bodger, P.S. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    For a future driven by technology and businesses built on knowledge and innovation, the role of R&D (Research and Development) between industry and academia plays a vital role in the way we do business. As a result, the function of project management in this area is of critical importance. Although inter industry-academia R&D is not a new concept, the guiding principles of project managing industry-academia R&D is by nature somewhat delicate and undefined. However, an organisation that has gained unique experience in this area is the Electric Power Engineering Centre (EPECentre).The EPECentre is an industry funded Centre of Excellence for electric power engineering, hosted within the University of Canterbury, in Christchurch. The experience of the EPECentre in R&D and lessons learned on the intricacies of inter industry-academia R&D project management has revealed ‘insider’ information on issues such as understanding cultural differences between industry and academia, allowing for contingency to operate in this environment, achieving realistic deliverables, etc., knowledge which could potentially add value to any organisation wishing to establish R&D links with academia and create win-win situations for both industry and academia – two cultures, joint success!

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  • Controlled Assembly of Gold Nanoparticles on Carbon Surfaces

    Downard, A.J.; Tan, E.S.Q.; Yu, S.S.C. (2006)

    Journal Articles
    University of Canterbury Library

    Citrate-capped gold nanoparticles are electrostatically assembled on amine films attached to carbon surfaces. Primary amines are covalently grafted to carbon surfaces by an electrochemically-assisted method which gives easy control of the number of amine functionalities on the surface, and hence the density of the nanoparticle assembly. Further control of nanoparticle assemblies can be gained by choice of the amine modifier, and by adjusting the nanoparticle concentration, assembly time and pH of the nanoparticle solution. This simple and versatile approach for preparation of tethered nanoparticle assemblies should be compatible with any conducting carbon substrate, giving new materials for applications ranging from catalysis to sensing.

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  • Factors Affecting Resilient Modulus

    Saleh, M.F.; Ji, S.J. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    Resilient modulus is an important property for asphalt concrete design and for mechanistic analysis of pavement response under traffic loading. This study investigates the different factors affecting the resilient modulus of hot mix asphalt. A fractional factorial design of experiment was carried out to investigate seven factors each factor was studied at two levels. These factors are: the maximum nominal aggregate size, specimen diameter and thickness, the load pulse form and duration, preset strain level and the compaction method. Two types of hot mix asphalts with different maximum aggregate sizes (10mm and 14mm) were studied. Gyratory and Marshall compaction methods were used to prepare the specimens. All mix specimens were compacted to the same air voids content (5.0±0.5%). Sinusoidal and triangular load pulse forms were used in the measurement of the resilient modulus. This study attempts to examine how the different factors interrelate to affect the resilient modulus. It was found that the most significant factor affecting the resilient modulus value is the maximum nominal aggregate size followed by the load duration period, specimen thickness, specimen diameter, compaction method and strain level, and then the interaction between specimen diameter and thickness, the interaction between aggregate size and thickness, aggregate size and compaction method. The effect of wave pulse form whether triangular or sinusoidal was found that it has no significant difference of the resilient modulus value.

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  • Advanced Flag-Shaped Systems For High Seismic Performance

    Kam, W.Y.; Pampanin, S.; Palermo, A.; Carr, A. (2006)

    Conference Contributions - Published
    University of Canterbury Library

    listed in poster section of abstracts book

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  • FluidStream 7.0 – System Theory and Design

    Nokes, R. (2007)

    Authored Books
    University of Canterbury Library

    System theory and design of FluidStream, a particle tracking velocimetry (PTV) system that processes digital images and produces two dimensional velocity fields.

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  • Accumulation and fate of contaminants (Zn, Pb, Fe and S) in substrates of wetlands constructed for treating mine wastewater

    O'Sullivan, A.D.; Moran, B.M.; Otte, M.L. (2004)

    Journal Articles
    University of Canterbury Library

    Substrates of treatment wetlands, which were constructed at an operational lead-zinc mining facility (Tara Mines) in Ireland, were analysed over a 5-year period for metal content. Lead, zinc, iron and sulphate were removed from wastewater passing though the treatment systems and were significantly retained in the substrates. The degree to which these contaminants are bio-available depends on the biogeochemical conditions of the substrates, namely the pH, redox potential, amount of organic carbon present and the contaminant loading. Various sediment fractions (water-soluble, exchangeable, carbonate-bound, organic matter-bound and residual) were also analysed in these treatment wetlands, in order to estimate the fate of metals and sulphur over time. Results showed that the majority of metals and sulphur were retained in immobile residual forms, principally as metal-sulphides. Furthermore, the neutral-alkaline pH and reducing biogeochemistry of the treatment systems suggest that metals are not toxic under these conditions.

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  • ImageStream 6.0 – System Theory and Design

    Nokes, R. (2007)

    Authored Books
    University of Canterbury Library

    System theory and design of ImageStream, an image processing program that supports a variety of image analysis algorithms. These algorithms are typically used for analyzing images captured with a laser induced fluorescence (LIF) system or other optically based experimental techniques.

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  • ImageStream 6.0 – User’s Guide

    Nokes, R. (2007)

    Authored Books
    University of Canterbury Library

    User guide for ImageStream, an image processing program that supports a variety of image analysis algorithms. These algorithms are typically used for analyzing images captured with a laser induced fluorescence (LIF) system or other optically based experimental techniques.

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  • A Contour Integration Method for the Computation of Zernike Moments of a Binary Image

    Mukundan, R. (1997)

    Conference Contributions - Other
    University of Canterbury Library

    Zernike moments are widely used in several pattern recognition applications, as invariant descriptors of the image shape. Zernike moments have proved to be superior than other moment functions in terms of their feature representation capabilities. The major drawback with Zernike moments is the computational complexity. This paper presents a fast algorithm for the computation of Zernike moments of a binary image. The Zernike moment integrals are evaluated along the object boundary points using a discrete version of the Green’s theorem. The real-valued Zernike radial polynomials are computed with the help of a recursive procedure. The performance of the algorithm based on contour integration is faster and more accurate than the moments evaluated using the whole image. Experimental results are presented for the image of a ellipse shape. The exact (analytically derived) values of the Zernike moments are compared with the numerically evaluated moments of the discretized image, using both the conventional direct sum method and the contour integration method.

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  • Improving Image Reconstruction Accuracy Using Discrete Orthonormal Moments

    Mukundan, R. (2003)

    Conference Contributions - Published
    University of Canterbury Library

    Several pattern recognition applications use orthogonal moments to capture independent shape characteristics of an image, with minimum amount of information redundancy in a feature set. Legendre, Zernike, and Pseudo-Zernike moments are examples of such orthogonal feature descriptors. An image can also be reconstructed from a sufficiently large number of orthogonal moments. Discrete orthogonal moments provide a more accurate description of image features by evaluating the moment components directly in the image coordinate space. This paper examines some of the problems associated with the computation of large order Tchebichef moments, and proposes an orthonormal version to improve the quality of reconstructed images.

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