Showing papers by "University of Canterbury published in 1978"

Seismic response of structures free to rock on their foundations

Abstract: SUMMARY The possibility of foundation rocking of shear wall structures designed to NZS 4203 is discussed. Theory developed by Housner for the free rocking of a rigid block is compared with experimental results from a simple structural model with a number of different foundation conditions. A simple design method for assessing maximum rocking displacements, using equivalent elastic characteristics and a response-spect ra approach is proposed, and compared with results from simulated seismic excitation of the model using an electro-hydraulic shake-table. A typical design example is included.

The Rapid Synthesis and Destruction of Photoreceptor Membrane by a Dinopid Spider: A Daily Cycle

Abstract: The receptive segments of the posterior median eyes of Dinopis subrufus are hexagonal in transverse profile, and each of the six faces is composed of a rhabdomere. Supportive cell processes are reduced to strands at the junction of the rhabdoms, and each of the six rhabdomeres, therefore, is contiguous with the rhabdomere of a different receptive segment; this arrangement allows the possibility of both optical and electrical coupling between cells. During the day, receptive segments are short, and rhabdomere membrane occupies only a small proportion of their volumes. At nightfall, the segments lengthen, and novel membrane is added in a rapid burst of synthesis almost to fill them. At dawn, the sequence is reversed, and membrane is removed as pinocytotic vesicles which are assembled into multivesicular bodies and lysed in the inter-rhabdomeral cytoplasm and in the swollen receptor axons which underlie the retina. Synthesis and destruction of membrane are shown to be controlled in part by immediate states of retinal illumination, superimposed upon a daily rhythm. It is argued that the evolution of this metabolically extravagant system is unlikely to be primarily concerned with the manipulation of states of adaptation, and some alternative hypotheses are proposed to account for it.

Graph theoretic heuristics for the plant layout problem

Abstract: The plant layout problem is an important industrial problem that remains unsolved. Seppanen and Moore considered an important subproblem: that of the optimal specification of which facilities are to be adjacent in the final layout without regard to the area or shape of the individual facilities. They present a string processing heuristic which relies on using a test for graph planarity. This paper further develops their graph theoretic formulation of the problem. This development is used to present two procedures which usually yield near-optimal solutions. The procedures circumvent the considerable difficulty of graph planarity testing by working entirely within a family of graphs known to be planar and also to contain the solution. Ways of improving suboptimal solutions are discussed. Computational experience in using the methods on a variety of problems suggests that the methods are efficient.

Static power conversion from self-excited induction generators

Abstract: Schemes based on synchronous generators and high-voltage d.c. transmission are often used to exploit remote natural energy resources. However, unless the provision of synchronous power at the sending end is essential, such schemes are unnecessarily complex. The paper describes an alternative solution using self-excited induction-generator/controlled-rectifier units, which eliminate the problems of voltage and frequency variations inherent in self-excited induction machines. Theoretical and experimental results are provided showing that the self-excited induction generator can operate in the linear region of the magnetisation curve while feeding a variable d.c. load at constant voltage. It is also shown that the unit can be used to feed controllable power into an existing a.c. network through a d.c. transmission link.

Dispersive Sources in Uniform Ground-Water Flow

Abstract: Solutions are given for instantaneous, continuous, and steady-state sources of pollution in uniform ground water flow. Then these solutions are used to determine how long a continuous source must be in place before steady-state conditions are approached, to determine the effect of a finite aquifer depth upon solutions for an infinite aquifer depth, to calculate maximum concentrations for instantaneous sources, and to determine the time required for solutions for a point source and a source of finite size to approach each other.

Tardigrada of New Zealand

Abstract: This paper treats the biosystematics of 55 species of Tardigrada found in New Zealand and its offshore islands. The genera Oreella, Echiniscus, Pseudechiniscus, Hypsibius, Macrobiotus, Limmenius n.gen., and Milnesium are represented. Areas sampled included Campbell Island, the Chatham Islands, D'Urville Island, the North Island, the Open Bay Islands, the South Island (and small islands in Fiordland), The Snares islands, Stewart Island, and the Three Kings Islands. There were 1354 collections comprising algae, bryophytes, fungi, lichens, and marine, freshwater, litter, and soil samples. Tardigrades were recovered from 577 terrestrial and semi-terrestrial habitats; no marine tardigrades were found. The systematics section includes keys to the taxa, illustrations, diagnoses, and descriptions of species. The following new species and subspecies are described - Echiniscus (Echiniscus) nigripustulus, E. (E.) porabrus, E. (E.) viniculus, E. (E.) zetrotrymus, Hypsibius (Hypsibius) allisoni, H. (Isohypsib...

The macroinvertebrate fauna of a New Zealand forest stream

Abstract: The distribution, abundance, and life histories of benthic invertebrates were investigated in a small, Nothofagus forest stream in North Canterbury, South Island, New Zealand. The fauna was dominated by Trichoptera and Plecoptera; Mollusca and fish were absent. Large particle detritivores and scrapers were the predominant functional groups found. Larval Philopotamidae (Trichoptera) were the only abundant filter feeders. Nymphs of the stonefly Spaniocerca zelandica and of mayflies, Deleatidium spp., were the most abundant animals on plant detritus; Deleatidium spp. were abundant on stones also. The distribution of invertebrates in riffles, loose stones, pools, and plunge pools was examined using mesh colonisation trays lifted in September, November, February, and May after respectively 88, 69, 98, and 94 days in situ. Most species were widely distributed, and sample densities of the more abundant insect species showed weak positive correlations with the biomass of detritus present in trays in most...

The Rhabdomere organization of some nocturnal pisaurid spiders in light and darkness

Abstract: The retinae of the posterior eyes of pisaurid spiders in the genus Dolomedes are described.They resemble those of Lycosidae, but the receptors are much larger, and proximal to the strips of tapetum upon which they rest the receptor axons are grossly dilated. Each receptive segment contains two rhabdomeres, and pairs of rhabdomeres belonging to adjacent receptors are contiguous. Prolonged (6 h) illumination at physiological levels causes the rhabdomeres to diminish in volume by loss of membrane which is restored on return to darkness. W hen spiders are kept in darkness for 4-5 d, the rhabdomeres grow by the orderly addition of membrane to the microvilli until they completely fill the receptive segments, and such novel membrane is subsequently disassembled when the retina is illuminated. It is proposed that under normal conditions there is a balance maintained between the growth and destruction of rhabdomere membrane. The paired rhabdomeres are flanked by the processes of supportive cells which exhibit much membrane amplification, and the supportive cell system extends below the tapetum completely to ensheath the swollen receptor axons, which are some 70-80 pm long. In dark-adapted retinae the supportive processes are shrunken; illumination causes them to swell, and the extracellular space between the interdigitations fills with electron-dense material derived from the breakdown of rhabdom ere membrane. The material is passed basally and reintroduced into the receptor axons via an extensive system of endocytotic pleats. The tips of pleats often enclose pigment granules from the supporting system, and identical granules in various states of lysis are found within the axoplasm after exposure to light, thus implying that the pleats burst rather than merely transport material across their membranes. There is evidence that pleats may become detached. Exposure of retinae to infrared radiation also evokes breakdown of rhabdomere membrane, but the extracellular route is not employed. The swollen axons are filled with whorls of rough endoplasmic reticulum, abundant Golgi bodies, and mitochondria. After long periods of darkness, all these systems are depleted, and the space they occupied becomes highly vacuolated. Light adaptation from dim light on a normal diurnal cycle evokes dilation of the cisternae of the endoplasmic reticulum, which pinch off smooth vesicles, and the Golgi bodies become highly active and produce coated vesicles in abundance. The relations between smooth vesicles and microvilli are ambiguous; precedents exist for supposing that smooth vesicles in the inter-rhabdom eral cytoplasm are pinocytotic and have been pinched off from the bases of the microvilli, but in Dolomedes there is some evidence to suggest that they may be identical with those manufactured by the endoplasmic reticulum and are also fusing with rhabdomere membrane. Multivesicular and multilamellar bodies are the product of membrane fragments which have broken off from the rhabdomeres during light adaptation, and of coated vesicles produced by pinocytosis; they are transported within the receptors to the swollen axons where they undergo lysis. It is proposed that in Dolomedes the role of the endoplasmic reticulum is to synthesize materials for the repair of rhabdomere membrane, and that the bulk of precursors to sustain this process is obtained by recycling the products of rhabdom ere breakdown via the supportive cell system. The hypothesis is discussed in terms of current information about invertebrate retinae, and analogous processes which are well established for those of vertebrates. Dolomedes do not move retinal pigment granules to modulate the shielding of their receptors, and it is likely that manipulation of the properties of photoreceptor membrane is the only strategy of adaptation available to them.

Studies on the photoreceptors of Anchoa mitchilli and A. hepsetus (Engraulidae) with particular reference to the cones

Abstract: Photoreceptors of anchovies Anchoa mitchilli and A. hepsetus consist of normal rods and two unusual kinds of cones. The latter lie in single vertical rows, and the rods lie between them. Both participate in photomechanical movements, and movement of the cones is closely coordinated with that of pigment cell processes. There are long cones having a cuneate outer segment and short cones having a bilobed outer segment. Long and short (bifid) cones alternate within a row and are staggered between adjacent rows. Both kinds possess calycal processes; long cones have a lateral sac or accessory outer segment. The long and short cones are associated to form a structure called a cone unit, which consists of the outer segment and ellipsoid of a long cone joined to two outer segment lobes of two adjacent short cones. The lobes of the latter are partly enclosed by the ellipsoid of the long cone. A cone row consists of a row of cone units isolated from each other by processes of the pigment epithelium containing stacks of guanine crystals which form a tapetum. Dorsal and ventral faces of inner segments have contact zones characterized by subsurface cisternae. Lamellae in the cone outer segments are arranged longitudinally with respect to the cell axis and short and long cone lamellae are perpendicular to each other; lamellae of the rods are transverse. Long cone lamellae are perpendicular to the cone row, and in the central retina are almost horizontal to the long axis of the body. Some vesicular/tubular structures also occur in the cone outer segments. Outer and inner segments of cones are joined by a broad connecting structure containing a stalk and root portion corresponding to a modified and reduced cilium shaft and centriole, respectively. The rod has a typical connecting stalk. Mitochondria of cone ellipsoids have expanded perimitochondrial spaces between outer and inner membranes. The organization of the anchovy cones is compared with that of other vertebrates. It is suggested that the cone unit may be a two channel analyser for the detection of plane polarized light and function in conjunction with the overlying reflector of regularly arranged platelets.

Fast-decoupled three-phase load flow

Abstract: Using as a reference the single-phase fast-decoupled algorithm, this paper describes the modifications required to produce an efficient three-phase fast-decoupled load flow. The compound-coil concept is used in the representation of power-system components, and the effect of automatic voltage regulators is modelled as part of the reactive-power Jacobian-matrix equation. It is shown that the three-phase modified fast-decoupled load flow displays all the characteristics of the original single-phase version.

A Place for Plastic Space

Abstract: Circumstances on the surface of the earth, for various more or less accidental reasons, suggest conceptions which turn out to be inaccurate, although they have come to seem like necessities of thou...

Global capacity reduction and schizophrenia.

Abstract: This paper reviews the evidence for a specific deficit in the flow of information through the schizophrenic processing system. It is suggested that there is little to support the notion of a single defective mechanism underlying schizophrenic cognitive dysfunction. The lack of a valid and reliable metric for measuring degree of difficulty across tasks and a lack of concern with matching tasks for attentional processing load, detracts from the usefulness of available results. The applicability of a global limited capacity model of selective attention to schizophrenic information processing is discussed as the most appropriate means of systematizing the wealth of published empirical data.

Hermaphroditism as a reproductive strategy for metazoans; some correlated benefits

Abstract: The concept of hermaphroditism is examined, the terminology is reviewed, and several new terms are proposed: EUHERMAPHRODITISM for the occurrence together of eggs and sperm in the individual that produced them; TEMPORARY HERMAPHRODITISM for the few instances where euhermaphroditism is a brief transitional phase between sexes in protandry and protogyny, and opsiautogamy to designate the condition where sperm saved from an early male phase are used to fertilise eggs produced in a later female phase. An animal that functions successively in the different sex roles is considered to be quite distinct from one that functions as both male and female simultaneously. Further, the circumstances in which these different sexual modes are appropriate and the advantages that accrue from them are quite different. For this reason protandry, protogyny, and consecutive sexuality are not considered to be part of hermaphroditism, but rather aspects of labile gonochorism. A major idea advanced in this paper is that h...

A rate-type constitutive model for soil with a critical state

Abstract: A continuum representation for soil which incorporates the concepts of hypoelasticity and critical state theory is proposed. General, three-dimensional constitutive equations are formulated to relate specific volume, stress, rate of deformation and rate of change of stress, resulting in a mathematical material model which exhibits phenomenological features typical of soil response. The general constitutive equations are specialized to represent the particular cases of isotropic compression, constant, volume deformation, uniaxial compression and biaxial deformation. Methods are suggested for determining the model parameters to represent a specific soil using conventional triaxial test data. Comparisons of stress-strain response with published experimental data are shown.

Relative pollen representation in relation to vegetation composition, Westland, New Zealand

Abstract: Moss cushions were collected at six localities near Harihari, South Westland, and analysed for their pollen content. Basal area data were compiled for all plants over 1.5 m tall at each locality. Comparison of vegetation and pollen data indicates that Coprosma, Phyllocladus, and Cyathea are over-represented; Dacrydium cupressinum, Quintinia, Pennantia, and Dicksonia are more-or-less proportionately represented; and Weinmannia, Dacrycarpus, Metrosideros, Podocarpus ferrugineus, P. spicatus, and Dacrydium colensoi are under-represented. Limited application was found for R-values in this study.

Narmada-Son Lineament of India Traced into Madagascar

Abstract: An extension of the Narmada-Son lineament of peninsular India can be traced across northern Madagascar, the lineament having been continuous in Gondwanaland. The Indian section, now a narrow seismicrift, appears to be a deep fault. It influenced Precambrian and Phanerozoic sedimentation and is the locus for post-Deccan Trap carbonatite and fluorite occurrences. The Malagasy section shows comparable unusual rocks. Postulated sinistral movement along the Indian section of about 450 km culminating at 750 Ma BP was associated with volcanism, plutonism and base metal mineralisation. The structure may not then have been in existence in Madagascar.

Fluid Dynamic Lift on a Bed Particle

Abstract: Direct measurement of lift forces acting on an exposed sphere at the boundary of a fluid flow shows that the lift force may be negative (i.e., directed toward the boundary) if the grain-size Reynolds number R* is less than about 5. The graphs presented strongly suggest that in a Newtonian fluid the dimensionless lift force is a function only of R*, in which case the results obtained can be expected to apply to exposed grains at the bed of a loose boundary flow if similarity of R* obtains. The onset of negative lift in such a situation as R* decreases through about 5 coincides with well-documented changes in bedform (from dunes to ripples) and in incipient motion conditions. It is suggested that the change of sign of lift force is a significant factor in these behavioral characteristics; physical mechanisms capable of effecting the observed changes are considered in qualitative terms.

A consideration of P-delta effects in ductile reinforced concrete frames

Abstract: The likely effects of secondary moments due to the gravity load, which is being laterally displaced during inelastic seismic storey drift, upon ductile reinforced concrete frames is examined. Existing building code recommendations and design procedures relevant to the phenomenon are briefly reviewed. The probable effect of P-delta moments on inelastic dynamic frame response is discussed. With the aid of illustrations various design considerations are presented. It is suggested that if strength demand due to P-delta effects exceeds 15% of the ideal lateral load carrying capacity of a subframe, this strength demand should be met. From the comparison of the elastic and inelastic deformations of a frame due to earthquake loading, recommendations are made for the estimation of critical inelastic drifts in the lower half of the frame. This is subsequently used to quantify the problem with the aid of the "stability index". The quantitative evaluation of P-delta effects for an 18 storey frame is illustrated in the appendix.

Protandry in the freshwater shrimp, Paratya curvirostris (Heller, 1862) (Decapoda: Atyidae), with a review of the phenomenon and its significance in the Decapoda

Abstract: Paratya curvirostris (Heller, 1862) (Decapoda: Atyidae) is the first member of its family found to be protandrous. Reappraisal of published information on Atya bisulcata, Atya serrata and Caridina richtersi indicates that they are also protandrous. The occurrence and biology of protandry in the Decapoda is reviewed. Analysis of available data suggests that protandry has no adaptive value and its frequency in these Crus:tacea is a result of the ease with which decapod reproductive physiology can be modified to produce the phenomenon.

Binaural Sensory Aid: Case Studies of Its Use by Two Children:

Abstract: The adaptation of the binaural sensory aid for use by blind children is discussed in the context of a pilot study carried out with two blind children; one an intellectually competent 6-year-old gir...

Plankton swarms and their predators at the Snares Islands (note)

Abstract: At times two species of euphausiids (Nictyphanes australis and N. capensis) and three species of hyperiid amphipods (Hyperia luzoni, Parathemisto gandichaudii, and P. gracilipes) occur in swarms close to the shores of the Snares Islands. Four species of birds (Daption capense, Diomedea bulled, Lams novaehollandiae, and Puffinus griseus) and six species of fish, including four reef fish (Latris lineata, Mendosoma lineatum, Notothenia angustata, N. microlepidota, Pseudolabrus cinctus and P. fucicola), were observed feeding on these Crustacea. These swarms seem to be important to the Snares Islands ecosystem as food for the large populations of petrels breeding there.

The sexual behaviour and genital mechanics of three species of Mynoglenes (Araneae: Linyphiidae)

Abstract: The sexual behaviour and genital mechanics of three species of Mynoglenes Simon 1905 are described, and compared with those of other species of Linyphiidae. A brief courtship is followed by sperm-web building and palpal induction by the male, the latter processes resembling those of Erigoninae. No intromissions are performed prior to induction. Courtship comprises elements common to both Erigoninae and Linyphiinae. The male palpal organ is simple, with a small curved paracymbium, an undivided suprategulum continuous with the tegulum, a large funnel-shaped conductor derived from the duct membrane, a radical component continuous with a filiform embolus, and lacks a lamella, terminal apophysis or other accessory processes of the embolic division: it is erigonine in character. The vulva comprises a well-developed scape of linyphiine type, and large atria which lead to spiral bursae terminating in small receptacula. Locking of the genitalia is achieved by the suprategulum catching in a socket on the ventral surface of the scape while the conductor lodges in the corresponding atrium so that suprategulum and conductor grip the vulva like callipers. Locking is sustained, and during its course the embolus is thrust through the channel formed by the conductor deep into the vulva and withdrawn many times. The mechanics of this unusual form of intromission are discussed, and shown to require three separate stages of haematodochal expansion; the first precedes locking, which is achieved by a backwards stab of the partially-expanded palp. The subocular secretory sulci present in both sexes play no role in sexual behaviour and are not used to engage the chelicerae of either partner, despite aggressive interactions in the early stages of courtship. The comparative aspects of these observations are discussed, with particular reference to the mixture of erigonine and linyphiine characters shown by Mynoglenes. It is argued that Mynoglenes and its allies, including the central African genera Afroneta and Trachyneta, constitute a relict group which preserves some ancestral linyphiid characters, and that subocular sulci may have been re-located in the course of evolution to provide the post-ocular sulci of male Erigoninae. In some genera, the latter are known to be gripped bv the females' chelicerae during copulation.

Occurrence of helical thickenings in the vessels of new zealand woods

Abstract: SUMMARY Helical thickenings were observed on the vessel walls of ninety woods indigenous to New Zealand. They were not observed in a further eighty-eight species. Four types of thickenings are described: faint striations, light helical thickenings sometimes merging with the vessel wall, prominent helical thickenings and very prominent close helical thickenings. These types are illustrated with scanning electron micrographs. Although the helical winding orientation was predominantly in the S-direction, considerable variation was observed in the helical winding angle both between adjacent vessel members of similar dimensions, and also within individual cells. Vestures were observed adhering to the helical thickenings in three species.

Dynamic Modelling of Single Generators Connected to HVDC Convertors

Abstract: The transient behaviour of 'unit-type' schemes consisting of HVDC convertors connected to isolated synchronous generators is analysed using state space theory and a numerical solution suitable for digital computation is described. Examples of computed results are illustrated including normal and disturbed operating conditions. These show that 'unit-type' schemes can operate satisfactorily with or without A. C. harmonic filters.