Abstract The research described in this article can be described as an explorative study that focused on obtaining and analysing perceptions and attitudes of public sector officials in Pretoria regarding the possible introduction of teleworking in their working environment. The term teleworking was understood in the sense of using computers to work from home or working at a distance away from the office. The research question that was posed was: What perceptions and attitudes exist among public sector officials in Pretoria that could contribute to, or impede, the acceptance of teleworking in South African government departments? Specific attention was given to perceptions of possible benefits or other impacts of teleworking, indications of public sector officials' ability to use computers for teleworking purposes, attitudes toward computers and teleworking, and the behavioural intention to use teleworking in future. The questionnaire and results were structured along the lines of the Technology Acceptance Model (TAM) of Davis. It was found that there was firm support among the officials for public sector teieworking - especially in terms of those views and perceptions that served as indicators for relevant TAM constructs such as 'perceived ease of use regarding teleworking', 'perceived usefulness of teleworking', 'attitude toward teleworking' and 'intention to use teleworking'.

This thesis explores the role of unequal power relationships between business enterprises in the UK brewing sector and how these asymmetries shape the dynamic and direction of changei n patternso f geographicailn dustrialisation.P ower has,t o date,r emaineda largely neglected concept in economic relationships as considered in economic geography. A new model of geographical industrialisation is developed in this thesis that focuses on capital: capital relations, incorporates the dynamic nature of enterprises and the networks of relations within which they are embeddedt,h e asymmetryo f power relations within and betweene nterprisesa ndt he dynamicc hangesin markets tructured uring periodso f recession and restructuring. It further seeks to explore the relationship between stability and instability in the derivation of emerging patterns of geographical industrialisation. The model is based on the concept of circuits of power (Clegg, 1989) which has been successfully applied to economic geography over recent years (Taylor, 1995,1996; Taylor and Hallsworth, 1996,1999; Taylor eta!, 1995). In this model inequalities in power between enterprisese stablishesth e basesu pon which competition can take place and go on to create the context within which social relationships are established and can develop. However, as currently specified this approach neglects the collective agency of enterprises inherent in segmented economic sectors (Taylor and Thrift, 1982a, 1982b, 1983). By the incorporation of appropriate insights from the study of complexity, collective agency, the element of process within the circuits of power framework, can be more fully understood. In this way those processes that create instability and flux in enterprises, but which at the same time lead to periodic stabilisations, can be identified. The thesis is divided into four parts. Part I. makes explicit the limitations of current theories of geographical industrialisation (Chapters 1 and 2) and proposes a new model (Chapter 2), incorporating the concepts of circuits of power and complexity, that addresses these limitations. Part II of the thesis (Chapters 3,4 and 5) tests the model against historical trajectories of change in the UK brewing sector identifying six cycles of change since 1700. For each cycle, by applying the model, the processes that have instigated and promulgated change are made explicit. Distinct enterprise segmentations, associated with each period of relative stability during these cycles, are also identified. Part III of the thesis, through a questionnaire survey (Chapter 6) and a series of semistructured interviews (Chapter 7), uses the model to examine the state of the UK brewing sector at the present time. Chapter 6 identifies contemporary enterprise segments active within the sector and the differential action of pressures upon these segments. In doing so the path dependent trajectories ofchange ofenterprise segments, and the limitations imposed upon such trajectories, are made explicit. Chapter 7 considers, through the model, the day to day interactions of enterprise segments and how these interactions reinforce the negotiated inequalities inherent in asymmetrical power relations. Coping strategies adopted by enterprises during a period of instability are identified and the relationship between the market and interpersonal relationships are made explicit. It is concluded that the model proposed in this thesis provides for a more realistic interpretation of changing patterns of geographical industrialisation than previous models

The thesis draws on historical and social policy perspectives to examine the factors influencing development and change in alcohol treatment policy between 1950 and 1990. The study uses data from primary and secondary documentation and from taped interviews. Three themes are highlighted as particularly relevant to an examination of policy trends. The first of these is the emergence and evolution of a `policy community'. Spearheaded by psychiatrists in the 1960s, the `policy community' broadened to include other professional groups and the voluntary sector by the 1990s. The second theme concerns the role of research in influencing the nature and direction of treatment policy. The study indicates increasing use of research as the rationale for policy and illustrates the move towards a `contractor' relationship between research workers and policy makers. The final theme deals with the influence on policy of ideological frames and changing conceptualisations of the alcohol problem. Two major shifts were important for treatment, the re-discovery of the disease concept of alcoholism in the 1950s and the emergence of a new public health model of alcohol problems in the 1970s. Within these broad themes, the study includes an examination of tensions - between different professional perspectives, between government departments with differing responsibilities, between different ideologies - and of moves to secure consensus in the formulation and implementation of treatment policy. The final chapter addresses shifts in thinking from the re-emergence of a `disease' model of alcoholism in the 1950s, to a `consumptionist' (population-based) model in the 1970s, towards a `harm reduction' approach to alcohol problems management in the 1990s. The thesis concludes that over the past forty years competing paradigms of the alcohol problem have emerged and gained policy salience within particular historical-social contexts in the search for policy consensus to manage the problematic aspects of alcohol consumption.

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This thesis consists of five essays on non-Walrasian economics. There are two essays on rational conjectural equilibrium, RCE, two on repeated games and one on general equilibrium with price-making firms and increasing returns to scale. The first two essays consider rational conjectural equilibrium from a game theoretic perspective. It is shown that (i) in general there is a continuum of RCE. (ii) Some interesting price behaviour, such as kinked demand behaviour and mark-up pricing can be supported as a RCE in a partial equilibrium model. (iii) Conjectural models can be regarded as a static representation of either a repeated game story with adjustment cost, or an instantaneous response repeated game, and that the rationality condition (in the 'correctness' sense) on conjectures amounts to sub-game perfectness in the super-game. In the third essay the solutions to repeated games with bounded memory are considered. It is shown that the Folk Theorem of repeated games (multiplicity of equilibria) can be extended to repeated games with one-period memory either if the action space of each player at each stage of the repeated game contains 'many elements' or if there is uncertainty. In the fourth essay the solutions to anonymous repeated game with a large but finite number of players are considered. In the fifth essay a General Equilibrium model with oligopolistic firms is developed (the model is based on my results in earlier chapters). Each oligopolistic firm is assumed to perceive (correctly) a kinked demand curve. I shall prove the existence of an equilibrium for such an economy without excluding increasing returns to scale or assuming concave revenue functions for the oligopolists.

Finite element simulation of metal cutting processes offers a cost-effective method to optimize the cutting conditions and to select the right tool material and geometry. A key input to such simulations is a constitutive model that describes material behavior during severe plastic deformation. However, the vast majority of material models used in prior work are phenomenological in nature and are usually obtained by fitting a non-physically based mathematical equation to the macro-scale stress-strain response of the material. Moreover, the deformation range covered by the stress-strain response used in the model calibration process usually falls short of the ranges typically observed in metal cutting. This thesis seeks to develop a unified material model that explicitly incorporates microstructure evolution into the constitutive law to describe the macro-scale plastic deformation response of the material valid over the range of strains, strain rates and temperatures experienced in machining. The proposed unified model is based on the underlying physics of interactions of mobile dislocations with different short and long range barriers and accounts for various physical mechanisms such as dynamic recovery and dynamic recrystallization. In addition, the inclusion of microstructure evolution into the constitutive model enables the prediction of microstructure in the chip and the machined surface. In this study, the unified material model is calibrated and validated in the severe plastic deformation regime characteristic of metal machining and is then implemented in finite element simulations to evaluate its ability to predict continuous and segmented chip formation in machining of pure metals such as OHFC copper and commercially-pure titanium (CP-Ti). Due to the physical basis of the proposed unified material model, the continuous chip formation observed in orthogonal cutting of OFHC copper is shown to be successfully predicted by the finite element model utilizing a version of the unified material model that explicitly accounts for microstructure evolution as well as dislocation drag as a plausible deformation mechanism applicable at the high strain rates common in metal cutting operations. The segmented or shear localized chip formation in orthogonal cutting of CP-Ti is also shown to be successfully simulated by the unified model after incorporating the inverse Hall-Petch effect arising from the ultrafine grain structure within the shear band. For both metals, the model is experimentally validated using flow stress data as well as machining data including cutting and thrust forces and relevant chip morphology parameters. Machining simulations carried out using the unified material model also yield useful insights into the microstructure evolution during the machining process, which is shown to be consistent with the available experimental data and the known physical understanding of severe plastic deformation behavior of the metals.

Electrochemical impedance spectroscopy (EIS) is a powerful technique that can be applied in-situ to deconvolute the various loss mechanisms in the polymer electrolyte fuel cell (PEFC) that occur at different rates. The frequency response of a PEFC that results from EIS is in essence characterised by energy dissipating and energy storing elements of the cell. It can be represented by an equivalent circuit that is composed of resistors and capacitors respectively. By understanding the arrangement and magnitude of the electrical components in the equivalent electrical circuit, it is possible to generate a deeper understanding of how and where the electrical energy that is generated due to the redox reaction is being dissipated and retained within the real physical system. Although the use of equivalent circuits is often an adequate approach, some electrochemical processes are not adequately described by electrical components. In which case, it is necessary to adopt a more rigorous approach of describing processes through the use of differential equations to describe the physics of the electrochemical system at the frequency domain. Studies in the literature have attempted to construct mathematical models to describe the impedance response of the cathode catalyst layer (CCL) based on conservation equations describing the electrochemical and diffusion processes. However this has resulted in a complicated mathematical analysis which in turn results in complicated solutions. The resulting equations cannot be easily validated against real-world EIS measurements and only analytical results have been reported. In this thesis a mathematical model to describe the impedance response of the CCL has been developed. This model is derived from fundamental electrochemical theory describing the physics of the CCL. The mathematical treatment is simplified by taking into account some considerations based on the EIS theory. The resulting model can be easily applied to real-world EIS measurements of PEFCs and presents parameters commonly known in the electrochemical area. The scientific contribution of this doctoral thesis is mainly divided in two sections: Modelling and Application. The first step of the modelling section develops an equation describing charge conservation in the CCL and together with Ohm s Law equation accounting for ionic conduction, predicts the impedance response of the CCL at low currents. The second step includes the change of oxygen concentration during the oxygen reduction reaction (ORR) into the equation accounting for CCL low current operation. The study of mass transport in the CCL is very complex; the literature has treated it with simplifications and approximations. The finite diffusion distance for oxygen to reach the reaction sites in the CCL forms a complicated network of multi-phase parallel and serial paths and can change in dimension at different operating conditions (flooding, drying). In the mathematical treatment of this doctoral thesis the finite diffusion distance and surface concentration of oxygen in the CCL are considered to be independent of the thickness of the CCL. EIS reflects only bulk measurements based on the total CCL thickness. Even though this results in an over-simplification for the oxygen diffusion in the total CCL, this approach simplifies the mathematical treatment to predict the impedance response of the CCL at high current operation, and as result it can be successfully validated against real-world EIS measurements. In the application section the model is applied with real-world EIS measurements of PEFCs. First the model is applied with EIS measurements presenting inductive effects at high frequencies. The model reveals mechanisms masked at high frequencies of the impedance spectrum by inductance effects. The results demonstrate that the practice of using the real part of the Nyquist plot where the imaginary part is equal to zero to quantify the ohmic resistance in PEFCs can be subject to an erroneous interpretation due to inductive effects at high frequencies. Secondly the model is applied to cathode impedance data obtained through a three-electrode configuration in the measurement system and gives an insight into the mechanisms represented at low frequencies of the impedance complex-plot. The model predicts that the low frequency semicircle in PEFC measurements is attributed to low equilibrium oxygen concentration in the CCL-gas diffusion layer (GDL) interface and low diffusivity of oxygen through the CCL. In addition the model is applied with simultaneous EIS measurements in an Open-Cathode PEFC stack. The factors that limit the performance of the PEFC stack are evaluated with simultaneous EIS measurements and the model. The results show that the change in impedance response of individual cells within the stack is attributed to oxygen limitations, degradation in membrane electrode assemblies (MEAs) and temperature distribution. This EIS knowledge enables an assessment of the state of health in operational fuel cell stacks. In the last section of the application section, the mathematical model translated in the time domain via reverse Laplace Transform predicts the current distribution through the CCL. This provides information to improve the performance of the CCL as well as determine the uptake of product water in the membrane. Finally the conclusions and future work are presented. This doctoral thesis has established a backbone understanding of how the electrochemical and diffusion mechanisms relate to the electrochemical impedance spectra of PEFCs. The goal of a future work is to develop this EIS knowledge into a real-time EIS system for non-intrusive diagnostics of degradation in operational PEFCs. This implies a modification of the model to consider oxygen transport through the CCL thickness as part of a multi-species mixture using mass transport theory including concentrated solution theory to fuel cell engineering.

The discounted cash flow model and relative valuation models are ever-increasingly prevalent in today’s investment-heavy environment. In other words, theoretically inferior models are used in practice. It is this paradox that has lead us to compare the discounted cash flow model (DCFM), discounted dividend model (DDM), residual income-based model (RIVM) and the abnormal earnings growth model (AEGM) and their relative accuracy to observed stockprices. Adding to previous research, we investigate their performance in relation to the OMX30 index. What is more, we test how the performance of each model is affected by an extension of the forecast horizon. The study finds that AEGM outperforms the other models, both before and after extending the horizon. Our analysis was conducted by looking at accuracy, spread and the inherent speculative nature of each model. Taking all this into account, RIVM outperforms the other models. In this sense, one can question the rationale behind investor’s decision to primarily use the discounted cash flow model in equity valuation.

Subcontractors perform the majority of the work on commercial construction projects. However, only limited research has focused on subcontractors’ practical needs. In response, this research discovered and documented subcontractor needs through data collections and extended these findings with development of an information model and tool. This research significantly enlarges detailed understanding of subcontractor management practices, in particular around resource allocation across multiple projects. While existing research has shown the importance of multi-project management, exploration of details of this process has largely been limited to overviews of policies. Rich details that allow for specific critiques of existing methods and tools have been missing. This research provides such details, including specific limitations and recommendations to existing information standards, commercial applications, and assignment algorithms. In particular, contributions of this research focus on support for what-if analysis under extreme frequency of resource reallocation, a limitation of existing tools and methods that make them unsuitable for most subcontractors. / text

Wind energy is one of the fastest growing sources of renewable energy in the world. There has been a lot of research, development, and investment in wind energy in recent years. Offshore sites offer stronger winds and low turbulence, along with fewer noise and visual impacts. Establishing large turbines at deepwater sites offers promising opportunities for generating high power output while utilizing the favorable environmental conditions. Researchers at Sandia National Laboratories (SNL) have developed a very large wind turbine model with a 13.2 MW rating that has 100-meter long blades; this turbine is designated as the SNL100 13.2 MW wind turbine. With a hub height of 146 meters and a rotor diameter of 205 meters, such a large turbine is best suited for offshore sites. Developing a wind turbine model for an offshore site requires that a platform model be developed first. Of the various kinds of floating platforms, a moored semi-submersible platform supporting the wind turbine, which offers stability by virtue of the intercepted water-plane area, is an appropriate choice. The goal of this study is to develop a semi-submersible platform model to support the 13.2 MW wind turbine, while keeping loads and deflections within safe limits. The platform is developed based on work completed as part of the Offshore Code Comparison Collaboration Continuation (OC4) Phase II project, which involved a 5 MW wind turbine supported by a semi-submersible platform. The present study focuses on three important topics: (i) development of the combined offshore wind turbine system model with the 13.2 MW wind turbine, a floating semi-submersible platform, and a mooring system; (ii) the entire procedure involved in modeling and analyzing first-order hydrodynamics using two codes, MultiSurf and WAMIT; and (iii) assembling of the integrated aero-hydro-servo-elastic model considering hydrodynamics in order to verify the steady-state and stochastic response of the integrated wind turbine system. / text