10,436 results for ResearchCommons@Waikato

  • The six days and the deluge: some ideas on earth history in the Royal Society of London 1660-1775

    Stokes, Evelyn (1969)

    Journal article
    University of Waikato

    The influence of the biblical story of Creation and the Deluge on ideas of earth history during the period 1660-1775 is examined with particular reference to papers on the subject published in the Philosophical Transactions of the Royal Society of London. Topics examined in more detail include the controversies over the origin of marine fossils and bones of prehistoric animals, ideas on natural causes of the Deluge and its role in shaping landforms, and the age of the earth. Despite the inhibiting effect of the Genesis account, there was considerable flexibility in interpretation of both the Creation and Deluge stories in terms of current scientific knowledge. The later papers display a good deal of uniformitarian thinking within the framework of a catastrophic deluge hypothesis.

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  • A simplified levelling instrument: the A-frame

    Riley, S.J. (1969)

    Journal article
    University of Waikato

    A levelling instrument has been developed which permits work in a high degree of detail without field assistance.

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  • Soil crusting in Western Samoa. Part I - Some examples of crusting and methods of control

    Reynolds, S.G. (1971)

    Journal article
    University of Waikato

    The problems and effects of soil crusting in Western Samoa are discussed. Illustrations of typical crust features include the glazed or 'frosted' surface of certain crusts, and dispersion mosaics. Surface mulches and fine wire mesh frames were investigated as control measures to dissipate the considerable kinetic energy of falling raindrops before they reach the soil surface. Soil crusting was much reduced by these control methods. Mulching increased the germination percentage of dwarf beans, and frames the germinating percentage of lettuce and cabbage over untreated plots; the yield of dwarf beans was increased by 80 per cent using a mulch of coconut fronds.

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  • The age of quaternary surfaces at Waihi Beach

    Selby, Michael J.; Pullar, W.A.; McCraw, J.D. (1971)

    Journal article
    University of Waikato

    The Waihi Beach surfaces were originally mapped and correlated with European surfaces of similar altitude by Kear and Waterhouse (1961). Exposures along the edges of the surfaces indicate that they are covered with volcanic ashes, the younger of which are of known age. It is the sub-ash surface which should be used for height correlations, and it is the most seaward ash-covered part of the surface which is preferred as the reference point for altitude studies. The heights of the surfaces may not correlate with positions of sea-level at the ages indicated by the ash beds.

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  • Mass movement in Tangoio conservation reserve northern Hawkes Bay

    Eyles, R.J. (1971)

    Journal article
    University of Waikato

    In a random sample of 52 valley-side profiles at Tangoio, mass movements are shown to occur preferentially on profiles with a northerly aspect, which are long, or steeply sloping. Detailed measurements of 27 debris slide and two slump scars dating from a storm in May 1971 enable an estimate of the rate of erosion of loess and volcanic ash from valley-sides to be made. Valley-side slopes are changing from a convexo-concave equilibrium form under the original forest towards a new, more rectilinear equilibrium form under grass.

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  • Book reviews and Book notices

    Waikato Geological Society (1971)

    Journal article
    University of Waikato

    Book reviews and Book notice from Volume 5, Number 2, 1971 of Earth Science Journal.

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  • Coverpage and Contents

    Waikato Geological Society (1971)

    Journal article
    University of Waikato

    Coverpage and Contents from Volume 5, Number 1, 1971 of Earth Science Journal.

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  • The origin of beach sediments on the North Queensland coast

    Bird, E.C.F. (1971)

    Journal article
    University of Waikato

    Petrographic and granulometric analyses of North Queensland beach sediments indicate their affinity with sediments delivered to the coast by rivers, and it is shown that the beaches are largely derived from fluvial sediment reworked, sorted and distributed by the dominant south-easterly waves in coastal waters. Beach sediments are generally quartzose, with subordinate felspars and admixtures of coralline sediment near fringing reefs and lithic material near river mouths and rocky shore sectors. The prevailing northerly drift of shore sediment is reduced, and locally reversed, on sectors sheltered from the dominant south-easterly waves by headlands, reefs and islands. Variations in beach sediment are related to wave conditions, distance from river-mouth sources, and patterns of drift. Four Mile Beach, near Port Douglas, is identified as anomalous in its morphological and sedimentological characteristics. It has been cut off from former sources of sediment, both fluvial and longshore, as a result of reef extension around the mouth of Mowbray River, and is now essentially a relict beach system attaining sedimentological maturity.

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  • Origin and distribution of mineral species in limestone caves

    Broughton, Paul L. (1971)

    Journal article
    University of Waikato

    More than 80 mineral species are known to result from secondary chemical reactions in solutional limestone caverns. These minerals are transitional and end-products of carbonate wall rock interactions with ground water and organic residue. Bacteria are often critical in fixing various ions in these reactions. Ultimate source of metallic ions is usually the sulphide minerals weathering in overlying strata, and brought to the cave environment by circulating ground waters. Hydrothermal solutions may bring heavy metallic ion concentrations from deeper strata. About one-third of the known cave mineral species occur in stalactitic form.

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  • Pared-down landscapes in Antarctica

    Cotton, C.A.; Wilson, A.T. (1971)

    Journal article
    University of Waikato

    The frigid-arid climate that now prevails in ice-free parts of Victoria Land, Antarctica, inhibits glacial erosion. If certain landscapes, more or less remote from the great troughs of outlet glaciers, have been glaciated in the past, as seems very probable, landforms that resulted from glaciation have been replaced by surfaces of different origin. A widespread landscape glaciation was probably contemporaneous with the excavation of large cirques which still survive in mountain summit areas. Replacement of glaciated landforms by others, in a general paring down of the land surface to forms of moderate relief, seems to have resulted from the process of gravity removal of debris from precipitous rock outcrops that were retreating because of disintegration by salt weathering and were eventually eliminated, in most cases, so that the landscape became a mosaic of smooth denudation slopes inclined at 33° to 350. In the Darwin Mountains ice-free area (80ºS) an advanced stage of such denudation with respect to a base level some 400 m above the present level of surrounding glaciers has produced some pyramidal landforms. Just above the present ice level, however, narrow Richter denudation slopes that border weathering rock faces are at only a juvenile stage of development. Thus the ice level appears to have stood alternately at about its present position and 400 m higher in Pleistocene interglacials and glacial ages respectively. The higher ice levels must have been due to extensions of the ice sheet seaward caused by groundings of the shelf ice during low glacio-eustatic stands of sea level

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  • Soil crusting in Western Samoa. Part II - Experimental investigation of factors influencing crust formation

    Reynolds, S.G. (1971)

    Journal article
    University of Waikato

    The Alafua Penetrometer was used to measure relative differences in soil crust strength. Crust strength and thickness were shown to increase with increases in rainfall amount, drying time, droplet size, kinetic energy and soil clay and silt content. The investigations were designed to illustrate some of the factors influencing crust formation to a diploma level soil conservation class.

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  • Further comments-Waihi Terrace and Hamilton Ash Ages

    Kear, David; Waterhouse, B.C. (1971)

    Journal article
    University of Waikato

    The authors of the previous paper (Selby et al. 1971) kindly allowed us to see their manuscript, prior to publication. They have made a significant contribution to Bay of Plenty late Quaternary stratigraphy in recognising established ash beds in the coastal terrace sequence at Waihi Beach (Kear & Waterhouse, 1961). This brief note acknowledges their work, and uses their data to produce an alternative age interpretation, that implies broad dates for the formation of each of the coastal terraces and for the Hamilton Ash.

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  • Volcanic studies by members of the Royal Society of London 1665 - 1780

    Stokes, Evelyn (1971)

    Journal article
    University of Waikato

    Late seventeenth century ideas about volcanic activity were largely derived from classical sources. The Philosophical Transactions of the Royal Society of London provided a vehicle for publication of information about volcanoes where many ancient notions were refuted and new hypotheses suggested. Volcanic studies by members included detailed field reports, eyewitness accounts of eruptions as well as expeditions to extinct or dormant volcanic peaks, experiments with volcanic rocks, and speculation on the nature of subterranean "fires" and causes of eruptions. The development of theories concerning the formation of the columnar basalts of the Giant's Causeway is also traced. By the 1770's there appeared a general acceptance among members of the Royal Society of the igneous origin of basalt, the existence of ancient extinct volcanoes and the implications of past geologic change.

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  • The significance of vegetation, fire and man in the stabilisation of sand dunes near the Warburton Ranges, Central Australia

    Conacher, A.J. (1971)

    Journal article
    University of Waikato

    The vegetation cover of sand dunes and sandplain country in a part of Central Australia is aperiodically destroyed by fire, caused by lightning and Aboriginal activities. Subsequent mobilisation, transportation and redeposition of sand by wind suggests that these vegetated sand dunes are currently unstable.

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  • Hydrological factors influencing sediment concentration fluctuations in small drainage basins

    Imeson, A.C. (1971)

    Journal article
    University of Waikato

    Although sediment concentrations measured in two contrasting streams in East Yorkshire fluctuate in response to similar hydrological factors, the effectiveness of these factors reflects the environmental characteristics of the drainage basins. Consequently, regression relationships used to predict sediment concentrations in individual streams are not directly applicable outside the region in which they were developed. The sensitivity of sediment concentration variations to environmental conditions makes long term estimates of denudation of limited value.

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  • Tensile Properties and Fracture Behaviour of Induction Sintered Ti and Ti-6Al-4V (wt %) Powder Compacts

    Raynova, Stiliana (Stella) Rousseva; Zhang, Deliang; Polo, D.; Gonthier, L.; Egea, W.; Nadakuduru, Vijay Navaratna (2011)

    Journal article
    University of Waikato

    Induction heating of powder compacts could be a very effective method for metal powder consolidation to get the final product or as an intermediate consolidation step to produce feedstock for metal powder forging or extrusion. Our study has proven that only a few minutes of induction heating, of Ti and Ti-6Al-4V (wt %) powder compacts, increases their density dramatically and causes a significant sintering effect, as evidenced by the formation of interparticle diffusion bonding and reflected by the tensile properties of the induction sintered powder compacts. This paper presents and discusses the results of a study on the tensile properties and fracture behaviour of the Ti and Ti-6Al-4V powder compacts sintered under a variety of induction heating conditions. Keywords: Titanium alloys, powder consolidation, powder compact sintering, induction heating.

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  • A study of polyvinyl butyryl based binder system in titanium based metal injection moulding

    Thavanayagam, Gnanavinthan; Zhang, Deliang; Pickering, Kim L.; Raynova, Stiliana (Stella) Rousseva (2012)

    Conference item
    University of Waikato

    Metal injection moulding (MIM) is an innovative injection moulding technique widely used to produce complex shaped components from feedstock composed of metal powders and thermosetting or thermoplastic binders. In MIM, binder selection and formulation are considered as critical processes since binder characteristics dictate the success of MIM. The purpose of this study is to determine the feasibility of polyvinyl butyryl (PVB) based binder system in Ti-6Al-4V(wt.%)/binder feedstock, as well as to understand the effects of key parameters, such as powder loading and mixing conditions on the rheological properties of a feedstock. In this study, PVB, polyethylene glycol (PEG), and stearic acid (SA) were chosen to formulate a multi-component binder system to prepare Ti-6Al-4V based feedstock with the aid of three types of mixers: a compounder, a modified mechanical mixer and a twin screw extruder. Further, morphological analysis was performed using optical microscopy and scanning electron microscopy. Thermal analysis was performed using simultaneous differential thermal analysis and thermogravimetric analysis. Results showed that binder formulation was reasonably successful with the aid of both mechanical mixer and a twin screw extruder under certain mixing conditions, and the critical powder loading was 68 vol.%, resulting in an optimum powder loading of 63 vol.%.

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  • A question of scale: How turbulence around aerial roots shapes the seabed morphology in mangrove forests of the Mekong Delta

    Mullarney, Julia C.; Henderson, Stephen M.; Norris, Benjamin K.; Bryan, Karin R.; Fricke, Aaron T.; Sandwell, Dean R.; Culling, Daniel P. (2017)

    Journal article
    University of Waikato

    Mangrove forests are highly productive ecosystems that provide many physical, societal, and ecological services in tropical and subtropical regions. Accurate prediction of the morphological evolution for these areas, in the face of global sea level rise and changes in sediment supply, requires understanding of interactions between vegetation growth, water flows, and sediment transport. Data presented from a waveexposed mangrove forest in the Mekong Delta, Vietnam, include unique measurements that resolved water flows in and around the aerial mangrove roots (known as pneumatophores) over scales from a few millimeters to hundreds of meters. Highly turbulent flow levels were as high as those measured in surf zones. These energetic processes appear to stir up sediments, with small scour pits observed around individual pneumatophores, and larger-scale scour around clusters of pneumatophores. The vegetation fringe (the boundary between forest and mudflat) was a particularly dynamic area, with elevated turbulence levels, greater vegetation densities, coarser sediments, and occasional wave breaking. Intense turbulent dissipation at the fringe then reduces the energy of shoreward-propagating waves, sheltering the forest interior. The small-scale processes appear to be linked with forest-wide patterns of sediment transport and deposition. We discuss these links in the context of the biophysical interactions that control the changing shapes of deltas worldwide.

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  • New public management and employee share ownership plan in Fiji’s public sector

    Sharma, Umesh Prasad; An, Yi (2013)

    Conference item
    University of Waikato

    This article provides insights into the implementation of new public management (NPM) practices in Fiji Telecom and whether the use of the employee share ownership scheme was helpful in the organisational change process. The NPM practices were influenced by the World Bank and International Monetary Fund who were the lenders to Fiji government. The adoption of NPM practices was part of a political, economic and public sector reforms introduced after 1989. The paper discusses the background and obstacles of the reform and how the employee share ownership scheme practice at a privatised Telecom Company assists employees to assimilate commercial business norms. The authors finally make recommendations for policy-makers in Fiji and other developing nations.

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  • Accuracy assessment of land surface temperature retrievals from Landsat 7 ETM + in the Dry Valleys of Antarctica using iButton temperature loggers and weather station data

    Brabyn, Lars; Zawar-Reza, Peyman; Stichbury, Glen; Cary, S. Craig; Storey, Bryan; Laughlin, Daniel C.; Katurji, Marwan (2013)

    Journal article
    University of Waikato

    The McMurdo Dry Valleys of Antarctica are the largest snow/ice-free regions on this vast continent, comprising 1 % of the land mass. Due to harsh environmental conditions, the valleys are bereft of any vegetation. Land surface temperature is a key determinate of microclimate and a driver for sensible and latent heat fluxes of the surface. The Dry Valleys have been the focus of ecological studies as they arguably provide the simplest trophic structure suitable for modelling. In this paper, we employ a validation method for land surface temperatures obtained from Landsat 7 ETM + imagery and compared with in situ land surface temperature data collected from four transects totalling 45 iButtons. A single meteorological station was used to obtain a better understanding of daily and seasonal cycles in land surface temperatures. Results show a good agreement between the iButton and the Landsat 7 ETM + product for clear sky cases. We conclude that Landsat 7 ETM + derived land surface temperatures can be used at broad spatial scales for ecological and meteorological research.

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