Since the early 1970s, exchange rate fluctuations have characterised the behaviour of the external value of many currencies in both high- and low-income countries. Up-and-down movements in real exchange rates have been observed under fixed as we:ll as flexible arrangements. This is in spite of the fact that many less developing countries (until the 1980s), unlike the major industrialised countries, opted to retain relatively rigid exchange rate systems after the collapse of the Bretton Woods system. Exchange rate volatility has been a subject of much concern in government, business and academic circles because it has been associated with negative effects on the performance of developing economies. Consequences of these large swings in exchange rates have included uncertainty and delays in business decisions, resource misallocation, interest rate volatility and real exchange rate misalignments. For the period, froln1970 to 1996, this study investigates the phenomenon of real exchange rate disequilibrium in developing countries, with an empirical and econometric examination of South African data. Using the ordinary least squares and the EngleGranger cointegration techniques, this investigation found that government consumption of nontradables, the price of gold in rand, the overall terms of trade and the rate of depreciation are important determinants of the short-run behaviour ofthe real effective exchange rate in South Africa. With regard to the long-run the permanent componen1ts ofthe fundamentals - namely, technological or productivity improvement, trade policy, governm1ent consumption of nontradables, disposable income, capital flows, the terms of trade excluding gold and the rand price of gold -, were found to be significantly related to the equilibrium conduct of the real effective exchange rate. Instances of real exchange rate misalignment were found in both periods of fixed and flexible exchange rate management. / Thesis (M.Soc.Sci.)-University of Natal, Pietermaritzburg, 1999.

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The concept of tiny machines capable of selectively transporting particles between two compartments by Brownian motion dates back to the 19th century when James Clerk Maxwell pondered the significance of a hypothetical ‘sorting demon’ being able to perform such a task adiabatically. This thesis report the design, synthesis and operation of a compartmentalized molecular machine in which the distribution of a Brownian particle, the macrocycle in a rotaxane, is controlled by using the lightinduced transmission of information to lower a kinetic barrier according to the location of the particle. For an ensemble of such machines the particle distribution is driven further and further away from equilibrium, providing a non-adiabatic realization of Maxwell’s pressure demon in molecular form. The nanomachine does not break the Second Law of Thermodynamics because the energy cost of the information transfer is met by externally supplied photons. As the molecular structure can be understood in chemical terms, it is possible in this experimental system to pin-point precisely how information is traded for energy. Intriguingly, the chemical mechanism can also be understood in terms of game theory. This is the first example of a synthetic molecular machine designed to operate via an information ratchet mechanism, where knowledge of the object’s position is used to control its transport away from equilibrium.

The study of non-equilibrium physics is an area of interest since, unlike for their equilibrium counterparts, there exists no general framework for solving such systems. In this thesis I investigate the emergence of structure and front propagation in driven systems, a special type of system within the area of non-equilibrium physics. In particular I focus on three particular one-dimensional models each of which illustrate this in a different way. The Driven Asymmetric Contact Process (DACP) describes a system where activity is continuously generated at one end of a one-dimensional lattice and where this activity is allowed to spread in one direction along the lattice. In the DACP one observes a propagating wave of activity which appears to abruptly vanish as the system undergoes a phase transition. Using a modified Fisher equation to model the system reveals the continued existence of the propagating wave, now contained within a decaying envelope. Furthermore this establishes relations between properties of the travelling wave and Directed Percolation critical exponents. The Zero-Range Process (ZRP) is a much studied system exhibiting a condensation transition. In the ZRP individual particles hop along a lattice at rates which depend only on the occupancy of the departure site. Here I investigate a modi cation of the ZRP where instead the majority of the particles at a site depart during a single hopping event. For this, the Chipping model, a condensate which propagates along the lattice is observed. It is found that this condensation transition is present even for hop rates which fall foul of the condensation requirements of the normal ZRP. Further it is observed that, unlike for normal ZRP, condensation occurs even in the low-density limit. As a result I suggest a condensation mechanism which depends only on the hop rates of low occupancy sites. The Host-Solute-Vacancy model (HSV) is a three-species system designed to model electromigration in a circuit. As the parameter space is navigated the system undergoes what appear to be two separate phase transitions from a randomly distributed state to a condensed state with either of two structures. To investigate the model new measures for determining condensation are developed. These show that, again, condensation occurs in the low-density limit. By a reduction to a ZRP an effective hop rate of the system is measured. This effective hop rate is found to beta function of the occupancy of a site as a fraction of the total system size. To explain this behaviour I invoke a description whereby there is a step in the hop rate as a function of occupancy. Through these three examples I illustrate how minor modi cations to the dynamics of known systems can result in a new and rich phenomenology. I draw particular attention to the effect of asymmetry in the dynamics.

Many chaotic and complicated systems cannot be analysed by traditional methods. In 1987 P.Bak, C.Tang, and K.A.Wiesenfeld developed a new concept called Self-Organised Criticality (SOC) to explain the behaviour of composite systems containing a large number of elements that interact over a short range. In general this theory applies to complex systems that naturally evolve to a critical state in which a minor event starts a chain reaction that can affect any number of elements in the system. It was later shown that many complex phenomena such as flux pinning in superconductors, dynamics of granular systems, earthquakes, droplet formation and biological evolution show signs of SOC. The dynamics of complex systems in nature often occurs in terms of punctuation, or avalanches rather than following a smooth, gradual path. Extremal dynamics is used to model the temporal evolution of many different complex systems. Specifically the Bak-Sneppen evolution model, the Sneppen interface depinning model, the Zaitsev flux creep model, invasion percolation, and several other depinning models. This thesis considers extremal dynamics at constant flux where M>1 smallest barriers are simultaneously updated as opposed to models in the limit of zero flux where only the smallest barrier is updated. For concreteness, we study the Bak-Sneppen (BS) evolution model [Phys. Rev. Lett. 71, 4083 (1993)]. M=1 corresponds to the original BS model. The aim of the present work is to understand analytically through mean field theory the random neighbour version of the generalised BS model and verify the results against the computer simulations. This is done in order to scrutinise the trustworthiness of our numerical simulations. The computer simulations are found to be identical with results obtained from the analytical approach. Due to this agreement, we know that our simulations will produce reliable results for the nearest neighbour version of the generalised BS model. Since the nearest neighbour version of the generalised BS model cannot be solved analytically, we have to rely on simulations. We investigate the critical behaviour of both versions of the model using the scaling theory. We look at various distributions and their scaling properties, and also measure the critical exponents accurately verifying whether the scaling relations holds. The effect of increasing from M=1 to M>1 is surprising with dramatic decrease in size of the scaling regime.

This thesis extends the literature on trade-linked international environmental policy by quantifying the effects of collective taxes on polluting intermediate inputs under varying trade, market structure and labour market assumptions. Using a CGE model augmented to include emissions from intermediate inputs, I simulate the effects of coordinated and harmonized environmental taxes on output, trade, and market structure. The main objectives are to ascertain whether free trade improves regulatory policy outcomes, and to demonstrate how market structure and the relative size of trading partners affect policy responses. To this end, I consider three cases: (a) asymmetric regions competing under perfect competition (b) asymmetric regions competing under imperfect competition and (c) symmetric regions competing under imperfect competition. Using Canada-EU and NAFTA-EU trade to represent asymmetric and symmetric trade ties, the results reveal the following: When regions are asymmetric, free trade unambiguously improves regulatory outcomes for the EU, but yields mixed results for Canada. In addition, regulatory costs are lower when trading partners are symmetric. However, free trade can result in perverse outcomes. For asymmetric regions, output and market structure changes are stronger under imperfect competition, and in the presence of real wage unemployment. Results also suggest that aggregate trade flows are not very sensitive to environmental taxes but are sensitive to changes in border taxes. Finally, welfare effects do not follow a predictable pattern because they partly depend on market structure changes.

Despite the prevalence of computable general equilibrium (CGE) models applied to tax changes of varying types, little work has been done focusing on state level comprehensive tax reform or on tax reform in countries undergoing a regime change. This research develops and applies methodologies for analyzing fiscal policy changes under these two very different economic scenarios. The findings for each application are relevant to policy makers as they weigh the effects of tax reform. The models developed for the two scenarios offer guidance to future modelers in studying similar economies and the contrast of the two provides a framework for thinking about model design and application. Finally, the results, when compared to each other, allow us to see the relative effectiveness of the two tax reform policies given their very different economies.

This thesis concerns the nature and time-scale of bed morphological adjustments towards equilibrium in alluvial meandering streams. Following the prevailing approach, the stream centrelines are assumed to follow sine-generated curves, the banks are fixed, and the flow is turbulent and sub-critical. The movable bed is flat at time t = 0; at t = Tb, the bed reaches its equilibrium or developed state. The specific objectives of this thesis are: 1) to develop a predictive equation for the bed development time Tb; 2) to determine the rate of growth of pool-bar complexes in meandering streams; and 3) to determine whether or not the large-scale, curvature-induced erosion-deposition zones of developing beds migrate upstream or downstream throughout their development. This thesis builds on the preliminary work and experimental tests by Binns (2006). The duration of bed development is found to be proportional to the square of the flow width B and inversely proportional to the channel-averaged bed-load rate (qsb)av, the proportionality factor being a function of the initial deflection angle (i.e., stream sinuosity). The form of this function is revealed on the basis of an extensive series of experimental runs carried out in meandering channels of varying values of the initial deflection angle (i.e., 20, 45, 70 and 95 degrees). In the present tests, the temporal development of the bed from time t = 0 to t = Tb was monitored by periodically stopping the flow in order to measure changes in bed surface elevation. In all runs the bed was observed to deform rapidly during the early stages of the run and slow down considerably as the bed approached equilibrium conditions. Once formed, the location of the erosion-deposition zones remained invariant in flow plan with the passage of time. Results from the runs are used to provide insight into the nature of the deformed bed in meandering streams. An expression describing the temporal rate of growth of pool-bar complexes in meandering streams of varying sinuosity is also proposed. The practical application of the equation for Tb is illustrated with available field data. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2012-01-26 16:43:52.424

There has been an increasing focus on using nanoscale devices for various applications ranging from computer components to biomechanical sensors. In order to effectively design devices of this size, it is important to understand the properties of materials at this length scale and their relevant transport equations. At everyday length scales, heat transport is governed by Fourier’s law, but at the nanoscale, it becomes increasingly inaccurate. Phonon kinetic theory can be used to develop more accurate governing equations. We present the moment method, which takes integral moments of the phonon Boltzmann kinetic equation to develop a set of equations based on macroscopic properties such as energy and heat flux. The advantage of using this method is that transport properties in nanodevices can be approximated analytically and efficiently. A number of simplifying assumptions are used in order to linearize the equations. Boundary conditions for the moment method are derived based on a microscopic model of phonons interacting with a surface by scattering, reflection or thermalization. Several simple, one dimensional problems are solved using the moment method equation. The results show the effects of phonon surface interactions and how they affect overal properties of a nanoscale device. Some of these effects were observed in a recent experiment and are replicated by other modeling techniques. Although the moment method has described some effects of nanoscale heat transfer, the model is limited by some of its simplifying assumptions. Several of these simplifying assumptions could be removed for greater accuracy, but it would introduce non-linearity into the moment method. / Graduate

The equilibrium properties of a spherical drop are investigated using the penetrable-sphere model of a fluid. To estimate the surface tension, a new statistical mechanical formula, the extension of the Triezenberg-Zwanzig result for a planar surface, is derived. The density profiles for use in this are obtained from an integral equation expressing the constancy of chemical potential through the interface. Numerical solutions can be obtained and from these numerical estimates for the surface tension. They are in good agreement with estimates from an independent thermodynamic route. These routes, as well as a further, zero-temperature, exact, analytic one, show that the surface tension of this model increases with decreasing drop size. The planar surface of the model is also briefly investigated using a well-known integrodifferential equation. Two approximations are made for the direct correlation function, one a systematic improvement on the other. They yield solutions for the density profile of a limited range of temperatures below the critical point. When the direct correlation function of a Lennard-Jones fluid is approximated the resulting equation for the profile resists numerical solution.