The mechanical properties of glassy poly (methyl methacrylate) have been examined by means of constant strain-rate tests at differing strain-rates and temperatures. Both fast-cooled and slow-cooled samples have been examined in order to determine the effect the rate of cooling has upon the mechanical properties. The ß and α’ relaxations were revealed in the experimental results. The difference in mechanical properties of fast- and slow-cooled samples could not be satisfactorily explained by the theory of Rusch.

The purpose of this research is the twofold one of attempting to answer some of the current problems in Engineering Hydrology and at the same time to provide analytical methods for the basic understanding of hydrologic systems. In order to design hydraulic structures such as spillways, dams, bridges, flood control and drainage schemes on a sound economic basis it is essential that accurate statistical data be available for the streamflow under consideration. Obtaining such data are: The two basic methods of (i) Statistical analysis of available streamflow records. (ii) Use of a deterministic catchment model together with statistical rainfall data.

Whole document restricted, see Access Instructions file below for details of how to access the print copy. / The stress-strain and strength properties of a residual soil sampled from the North Shore, Auckland, were investigated through stress and strain-controlled triaxial tests. Emphasis was placed on determining the behavioural characteristics of the soil under conditions of very low effective stress. The soil sampled was a silty clay, derived from the Waitemata Series, with the following average properties: natural water content 45.5%; initial bulk density l707 kg/m3; density of soil particles 2.63 t/m3; plastic limit 32; and liquid limit 60. The peak shearing resistance of the soil was observed to be accurately defined using the Mohr-Coulomb failure criterion, even at very low confining pressures. In addition, the Waitemata clay exhibited a measurable tensile strength of between 7.7 and 12.0 kPa. These results lead to the conclusion that the observed cohesion intercept for the soil could be relied upon for design purposes. The natural variation in void ratio of the Waitemata clay led to the use of total volumetric strain for improved stress-strain correlations. A modified critical state relationship for the soil was subsequently presented, with a unified soil model being used to predict the behaviour of the Waitemata clay. This model demonstrated the ability to replicate the general stress-strain and peak characteristics of the soil. The Waitemata clay did not display the yielding characteristics which are common to residual soils, rather the soil demonstrated continuous yielding behaviour. Anisotropy of the Waitemata clay was also found to be negligible. The use of volumetric strain in the calculation of consolidation properties required only simple modifications to existing consolidation formulae. Bender element tests enabled the small strain shear modulus of the soil to be evaluated. Comparisons of Gmax with the undrained shear strength produced a linear correlation (Gmax =284su) which was significantly lower than expected.

This thesis addresses the need for adaptability in vision systems that measure system state information in a sensory feedback role for the control and coordination of flexible discreteitem materials handling operations, such as those performed by a robotic palletising system. In addition, this thesis addresses the need for vision systems that are more easily configured by users, such as factory technicians and operators, who have lower skill levels than those generally required to (re-)configure a machine vision system. In response, a unique coupling mechanism and intuitive human-computer interface have been developed, hiding the complexity of image analysis from the end-user and simplifying the way that a machine vision system is configured. The mechanism couples machine vision-related "visual checks” to materials handling tasks in a generic framework of materials handling activities. Visual checks which define what control information is required are implicitly linked to image analysis functions which define how that information is extracted from digitised images of a materials handling system. Consequently, this research has developed a set of task - visual check "building blocks" that can be used in various combinations to define the sequence of actions and image analysis required to perform a variety of materials handling operations. In addition, a number of pre-defined task – visual check combinations and mechanisms for manipulating them have been developed, providing solution templates that can be used immediately or modified to suit application-specific requirements. These developments have been realised together with several aesthetic, ergonomic and functional features in a machine vision configuration interface, known as SlyVision. SlyVision's modularity, extensibility and upgradeability expressed to both the end-user and the system developer through its underlying object oriented architecture and intuitive user interface design make important contributions to its overall adaptability. Demonstrations involving a typical palletising and a de-palletising operation have shown how SlyVlsion is used to specify visual checks and configure the associated machine vision components without requiring the end-user to select or apply image analysis techniques or functions. In addition, the relative simplicity of the configuration process is demonstrated. Consequently, these developments assist people with limited understanding of machine vision technology to set up and maintain a vision system, thereby improving their ability to keep pace with frequent changes in their materials handling operations, while limiting the cost in time, money and effort required to (re-)configure a vision system. / Whole document restricted, but available by request, use the feedback form to request access.

This thesis describes the development of new semi-rigid joints for moment-resisting steel framed (MRSF) seismic-resisting systems. Intended as the weak link in the seismic-resisting system, in accordance with a strong column, weak joint philosophy, the joints and systems were designed and detailed to withstand the design level ultimate limit state (500 year return period) earthquake with minimum damage. To meet economic criteria, the joints and systems were also required to be cost-effective to design, fabricate and construct when compared with conventional MRSFS. Four joint systems between the beams and columns of a MRSF were considered. These were the: Ring Spring Joint (RSJ), where the beams are clamped to the columns with flush endplates and compressible ring spring elements Post-tensioned Tendon Joint (PTJ), where the beams are post-tensioned onto the columns with post-tensioning technology Flange Bolted Joint (FBJ), where the beams are bolted to the columns through flange and web plates that are designed and detailed to undergo dependable cyclic extension and compression under inelastic rotation demand Sliding Hinge Joint (SHJ), where the beam is pinned to the column at the top flange level and is connected at the bottom flange and the bottom of the web by a unique asymmetrical sliding shear detail The RSJ, FBJ and SHJ were developed through to the experimental stage, with large-scale tests on representative joints undertaken. The FBJ and SHJ were further developed, through small-scale static and dynamic testing, finite element and numerical integration time-history analyses into fully designed and detailed systems. Design procedures and detailing requirements for the two fully developed systems are presented, together with details of experimental testing, finite element analyses of joint components and numerical integration time-history analyses of complete structural systems. Design and detailing requirements for the joints and the frames are covered and fully worked design examples for the Flange Bolted and Sliding Hinge Joints are presented. The results demonstrate that the semi-rigid, strength-limited joints developed, when used in properly designed moment-resisting steel frames, have considerable advantages over conventional rigidly jointed frames for meeting strength, stiffness, ductility, damage-resistance and economic criteria. / There have been two amendments to the bolt design model developed in this research as a result of further development of the connection models developed in this work.

The motivation for this research is a proposed UHF surface wave communication system in which the waveguides are the stranded, overhead earth wires of Power System transmission lines. Attention is confined largely to an investigation of certain aspects which affect the overall surfaces wave transmission loss, a full-scale system having been set up in the laboratory for experimental purposes. For the prediction of transmission loss the stranded conductor is assumed to be equivalent to a solid conductor of the same diameter but with surface anisotropy in the form of two mutually orthogonal surface impedances the major reactive component of which is attributed to the effects of the helical stranding. This reactance is determined from a consideration of the fields which are assumed to exist within the cavities between the strands, and externally. From a comparison between experimental and theoretical loss characteristics there is sufficient inducement to accept the anisotropic model of the stranded conductor for practical design purposes. Approximate equations are developed to simplify the calculation of transmission loss and the notion of ‘capture cross-section’ is employed for the estimation of the efficiency of conical horn launchers. It is deduced from ‘sensitivity’ relationships that the horn loss is relatively insensitive to small changes in the fictitious surface reactance representing the effects of helical stranding, which tends to justify the assumptions upon which the anisotropic model is based. On the other hand, variations in the helix angle are shown to have a marked effect upon the calculated horn loss. This influences the choice of the stranded conductor used as the waveguide for the experimental verification of the model. The Author’s experimental research is described at length, the principal objective being to establish the anisotropic model as an acceptable theoretical substitute for the stranded conductor. To reduce the horn loss, dielectric sheaths are ted to the waveguide in the vicinity of the horn apertures. The discrepancies which then appear between theory and experiment are attributed both to the scattering of the surface wave by the boundary discontinuities at the ends of the sheaths and to the anomalous behaviour of commercial-grade PVC dielectric. Considering the increase in the transmission efficiency which may be realised by fitting dielectric sheaths to the conductor near the horn apertures it is concluded that a theoretical investigation of the scattering properties of the discontinuities s in order. Thus, the remainder of the Thesis is devoted, to this scattering effect as it may be encountered in the proposed scheme, the theoretical analysis following the lines of earlier documented research. A short-cut method is applied for the determination of certain ‘half-plane’ functions which appear in the expressions for the scattered power. Theoretical results are presented together with a discussion of some experimental measurements and a brief theoretical examination of the effects on the horn loss of varying the thickness of the dielectric sheaths. It is argued that the horn loss may be reduced if the dielectric thickness is graded in steps to a value at the horn apertures consistent with the desired ‘power capture’. The Thesis is concluded with an Addendum which outlines a number of topics suggested by the Author for future research.

Although the current thermoacoustic theory has so far proved successful in allowing us to analyse and understand thermoacoustic systems, there are inherent limitations associated with it. These are related to the fact that this theory is based on linear approximations. As designers search for ways to increase the efficiency and power density of thermoacoustic devices the accuracy of the linear theory decreases significantly, as a variety of non-linear effects start to become important. For example, when the pressure amplitude is increased, in order to increase the power density. This thesis concentrates on the non-linear effect of acoustic streaming. Acoustic streaming is a steady flow that is superimposed upon the acoustic Oscillations. An expression for the streaming velocity is developed for a parallel plate channel having an arbitrary gap width, so that the solution is valid for both thin and wide boundary layers. The solution includes thermal effects arising from the presence of an axial temperature gradient along the channel, and arbitrary phase between the pressure and velocity. An essential feature of the streaming velocity is the generation of circulating loops, which can cause heat to be convected within the channel. An expression for the transverse steady state temperature was also derived, for similar conditions as outlined for the streaming velocity. It was found that when an axial temperature gradient is present the magnitude of the transverse steady state temperature increases significantly as the width of the channel increases. The implication of this is that a significant amount of heat can be convected along the channel due to the action of the streaming velocity. When no axial temperature gradient is present, the transverse steady state temperature reduces to a small constant value outside the boundary layer. A numerical finite difference scheme was developed to model non-linear flow within the two-dimensional channel. The model solves for the conjugate fluid-solid problem enabling the temperature difference induced along the channel to be predicted. The model compared very well to experimental data. It was also found to be in excellent agreement with the analytical solutions for the streaming velocity and the transverse steady state temperature. The effect of streaming on the energy flux density was examined for a wide channel, having a temperature gradient along its length. A fourth-order expression was developed, which yielded a solution in terms of the transverse steady state temperature and second-order mass flux, which for certain conditions could be of a similar magnitude as the second-order terms. For a thermoacoustic core, it was proposed that a toroidal flow could form and convect heat from one heat exchanger to the other. To analysis this effect toroidal flow was incorporated into an expression for the temperature difference induced across a thermoacoustic couple. This result was found to be in excellent agreement with experimental data. The effect of toroidal streaming on the thermoacoustic core was also considered. In addition, a second-order expression for the work flux was derived that included a previously ignored term due to acoustic streaming.

This study is concerned with a theoretical, laboratory and in situ investigation of the propagation of seismic stress waves through soil media. Analyses are carried out to predict the surface response that results from earthquake motions being transmitted through the upper layers of the earth. The nature of the near surface geological layers affect to a marked degree the intensity of surface motion. The mathematical models presented are used in the evaluation of site response to earthquakes. The theoretical methods used depart from the traditional viscoelastic approach and use a nonlinear hysteretic soil model to describe the complex dynamic stress-strain relationships evident in soil response. The dynamic soil model is based on previous laboratory work carried out at this university. The theoretical solutions formulated are limited to one-dimensional situations. Three methods of analysis are presented for the propagation of seismic shear waves through nonlinear soil media and conclusions are drawn as to the best approach. The results of these analyses are generally significantly different from those obtained using a viscoelastic soil model. Seismic dilatational waves are also considered important and a method is presented to calculate the response of hysteretic soil media to these disturbances. The outcome from these dilatational and shear wave analyses is more accurate surface response spectra for use in aseismic structural design.

The design of rubble mound breakwaters is typically based on empirical formulae and physical modelling. One limitation of this approach is that different aspects of wave interaction with a breakwater, such as the elevation of the runup tip and armour stability, are treated separately. Therefore the development of a numerical model of wave runup on a rubble mound breakwater was the primary objective of the research described in this thesis. Because of the range of slope conditions encountered with rubble mound breakwaters and revetments, two types of armour layer are considered. The first is impermeable and so only the flow within the external region is modelled. The flow is assumed to be governed by the unsteady one-dimensional shallow water wave equations and only regular waves are considered. It is shown how the use of the finite element method with a mesh of isoparametric elements that deforms and is fitted to the runup tip has a number of advantages over the traditional use of the finite difference method with a fixed grid. Reasonably good results were obtained for the numerical modelling of wave runup on a riprap armoured l:3 impermeable slope indicating that the numerical model may, in conjunction with a physical model, be of practical use in the design of revetments. Wave runup on smooth and Dolos armoured 1:1.5 impermeable slopes was modelled poorly. Therefore the model is more appropriate for wave runup on a revetment than a rubble mound breakwater. The second type of armour layer is permeable and so the flow within the external region and armour layer is modelled simultaneously by coupling numerical models for the respective regions. It is concluded that this approach is unlikely to give acceptable results for the runup of regular waves on a steep, permeable armour layer unless it also accounts for the non-hydrostatic distribution of pressure within the external region. An experiment is described in which continuous time histories of wave runup and dynamic pressure due to regular waves on smooth and Dolos armoured 1:1.5 slopes were measured. The results are used to discuss the assumption of hydrostatic pressure. A method of assessing armour stability requirements which takes into consideration the effects of armour unit interaction is proposed. It is recommended that this is examined further.

A new theoretical characterisation is developed for the off-axis stiffness of FRP materials. The theoretical model treats an off-axis unidirectional ply as an inhomogeneous material, and considers the effect of rigid body rotations of the fibres within the matrix material. Linear analytical, and nonlinear finite element solutions are developed for the model. The differences between the new model and the traditional homogenous orthotropic characterisation are functions of both the strain level, and the relative modulus ratio (Ef/Em) of the constituent materials. For relative constituent moduli typical of most common FRP materials, there are significant differences between the new Rigid Body Motion (RBM) model and homogenous orthotropic characterisations at strains greater than 1%. In a 30° case with Ef/Em = 100 and a strain level of 2%, the RBM theory predicts a longitudinal modulus 11% higher than the linear orthotropic theory. At small strain levels the RBM theory reduces to the homogenous orthotropic approximation. A simple and reliable methodology is developed and verified for the experimental characterisation of off-axis tensile FRP specimens. The method applies a tensile load to a thin walled tubular specimen through a high strength, small diameter length of steel wire. The low torsional stiffness of the wire allows one end of the tube to rotate, thus preventing any torsional constraint. Analytical and experimental verifications both indicate that the required tensile load can be applied to tubular specimens without significant torsional constraint. The wire based testing method is used to measure the off-axis stiffness properties of carbon/epoxy tubular specimens at a range of fibre orientations.