The study focuses on building a financial model for a telecommunications carrier to guide it towards profitable network investments. The model shows optimal access-network topography by comparing two broadband delivery techniques over fibre technology. The study is a scenario exploration of how a large telecommunication company deploying fibre will see its investment pay off in a Canadian residential market where cable operators are using competing technology serving the same bandwidth hungry consumers. The comparison is made at the last mile by studying how household densities, bandwidth demand, competition, geographic and deployment considerations affect the economics of fibre technology investment. Case comparisons are made using custom models that extend market forecasts to estimate future bandwidth demand. Market uptake is forecasted using sigmoid curves in an environment where competing and older technologies exist. Sensitivity analyses are performed on each fibre technology to assess venture profitability under different scenarios.

The study focuses on building a financial model for a telecommunications carrier to guide it towards profitable network investments. The model shows optimal access-network topography by comparing two broadband delivery techniques over fibre technology. The study is a scenario exploration of how a large telecommunication company deploying fibre will see its investment pay off in a Canadian residential market where cable operators are using competing technology serving the same bandwidth hungry consumers. The comparison is made at the last mile by studying how household densities, bandwidth demand, competition, geographic and deployment considerations affect the economics of fibre technology investment. Case comparisons are made using custom models that extend market forecasts to estimate future bandwidth demand. Market uptake is forecasted using sigmoid curves in an environment where competing and older technologies exist. Sensitivity analyses are performed on each fibre technology to assess venture profitability under different scenarios.

The cerebellum has historically been implicated solely in motor coordination. However, we now know it is a major associative center for sensory input. For example, the vestibulocerebellum (VbC) receives a large projection from retinal recipient nuclei in the Accessory Optic System and pretectum; these nuclei analyze visual optic flow information during self-motion and ultimately function in gaze stabilization. In birds, these nuclei project to the cerebellum directly, as mossy fibres, and indirectly as climbing fibres via the inferior olive. Therefore, there are parallel pathways carrying visual information to the cerebellum; these pathways show a remarkable modular organization. In fact, the pattern of cerebellar afferent and efferent connections, the physiological response properties of Purkinje cells, and a variety of molecular markers, all provide abundant evidence that the vertebrate cerebellum is organized into parasagittal zones. This modular organization exists across several different vertebrate species, suggesting that this basic principle of organization has been evolutionarily conserved and is necessary for fundamental information processing in the cerebellum. Although recent advances have increased our understanding of cerebellar organization, the relationship between these parasagittal patterns and the functional behavior of the cerebellum remains unknown. This dissertation seeks to tie together various features of the zonal organization of the cerebellum, using molecular, electrophysiological and neuroanatomical techniques, and to relate this organization to visual motion processing in the VbC. To investigate the parasagittal biochemical organization we use the molecular marker, zebrin (aldolase C), which is expressed by a subset of Purkinje cells, creating a striped appearance in the cerebellar cortex. We provide the first evidence of the zebrin parasagittal expression pattern in an avian species and then further elucidated the relationship between zebrin stripes and the visual afferent climbing fibre input, mossy fibre input, and the physiological zones in the VbC. There is a substantial, and growing, body of evidence that now suggests a more fundamental cerebellar architecture is built around arrays of parasagittal modules. By understanding the basic principles underlying this organization, we gain insights that may lead to a better understanding of the principles of modular organization in the central nervous system in general. / Neuroscience

Experiments in the study of transient aerodynamics typically require pressure measurements with a high spatial and temporal resolution. Existing commercial pressure transducers are expensive and they provide a spatial resolution only on the order of millimetres. The full bandwidth of commercial devices (which extends to around 200 kHz) can only be utilised by exposing the transducer to the flow environment with very little thermal or mechanical protection. If insufficient protection is provided, the expensive commercial devices are likely to be damaged. Inexpensive pressure sensors based on extrinsic Fabry-Perot fibre optic interferometry are capable of measurement with a high spatial and temporal resolution. Thermal protection or isolation for these sensors is still required, but they can be exposed directly to the flow if the sensors are disposable (low cost). Excessive thermal or mechanical protection is not required for these sensors because the damaging heat transfer and particle impacts that may occur in transient aerodynamic facilities generally occur after the useful test flow. In this dissertation, a variety of construction techniques for diaphragm-based Fabry-Perot fibre optic pressure sensors were investigated and the advantages and disadvantages of all techniques are compared. The results indicate that using a zirconia ferrule as the substrate, a liquid adhesive as the bonding layer, and a polished copper foil as the diaphragm provide the best results. It is demonstrated that a spatial resolution on the order of 0.1 mm and a bandwidth to more than 100 kHz can be achieved with such constructions. A variety of problems such as hysteresis, response irregularity, low visibility and sensor non-repeatability were observed. By using a thinner bonding layer, a larger bonding area, longer cavity length, increased calibration period, and applying load cycling to the diaphragm, the hysteresis was minimized. Sensor response irregularity was also minimized using a polished diaphragm. Visibility increased to about 90% using active control of the cavity length during the construction process. Non-repeatability was found to be a consequence of adhesive viscoelasticity and this effect was minimized using a thin layer of adhesive to bond the diaphragm to the substrate. Due to the effects of adhesive viscoelasticity, the pressure sensors indicate an error of up to 10% of mean value for the reflected shock pressure. This error could not be further reduced in the current sensors configuration. Some new configurations are proposed to decrease the effect of sensor non-repeatability. The effect of pretensioning the diaphragm was investigated analytically but the results do not indicate any considerable advantage for the levels of pretension likely to be achieved in practice. However, the results do indicate that pretension effects caused by an environmental temperature change can damage the sensor during storage. The effect of the initial diaphragm deflection on the sensor performance and temperature sensitivity was modelled and the results show that an initial diaphragm deflection can improve the sensor performance. The effect of the thermal isolation layer on the sensor performance was also investigated and the results show that for a shock tube diaphragm bursting pressure ratio up to 5.7, heat transfer does not contribute to sensor errors for the first millisecond after shock reflection. However, it was found that the use of a thin layer of low viscosity grease can protect the sensor for about 20 ms while only decreasing its natural frequency by typically 17%. The grease layer was also found to decrease the settling time of a low damping ratio sensor by 40%. The sensor was successfully employed to identify an acoustic disturbance in a shock tube.

Thesis (M.S.)--Texas State University-San Marcos, 2008. / Vita. Appendix: leaves 34-43. Includes bibliographical references (leaves 44-48). Also available on microfilm.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [86]-91).

Steam reforming of methanol and hydrocarbon are currently the processes of choice to produce hydrogen. Due to the endothermic nature of these reactions, zones of low temperature are commonly found in reformers. These zones can potentially damage the reformer through thermal stresses. Moreover, the response time and size of a reformer are controlled by the heat available to the reaction. The objective of this thesis is to demonstrate the feasibility of using fiber Bragg gratings as an alternative solution for temperature monitoring in methanol and methane steam reformers. To meet this objective, a sensor array containing seven gratings is placed in a metal-plate test reformer. First, temperature monitoring during methanol steam reforming is conducted in 12 different sets of conditions. The resulting profile of the temperature change along the length of the catalyst captures the zones of low temperature caused by the endothermic nature of the reaction. Several small changes in the temperature profile caused by increasing temperature and/or flow rates were captured, demonstrating the ability to use these gratings in methanol steam reforming. Similar experimental work was conducted to validate the possibility of using fiber Bragg gratings as temperature sensors in methane reforming. Using a regenerated grating array, data was collected for 13 operating conditions. The conclusions arising from this work are similar to those drawn from the methanol steam reforming work. The regenerated FBGs exhibited a behaviour that has not been reported in the literature which is referred to in this thesis as secondary erasure. This behaviour caused some instability in the grating signal and erroneous readings for some operating conditions. Despite this, the grating measurements captured the zones of low temperatures in the reformer and the small changes brought about by increasing the reforming temperature and lowering the steam to carbon ratio. / Graduate

D.Ing. (Electrical & Electronic Engineering Science) / The objective of the research performed in this thesis is to address the calibration process of Fiber-Optic Gyroscopes (FOGs) - a class of gyroscopes that make use of the Sagnac effect to determine rotational information from laser-light traveling in an optical fiber. The calibration process has traditionally been a time-consuming and therefore an expensive one due to the various environmental parameters that can influence the sensor under operation. Calibration is not a step that can be neglected as it is the process whereby the residual manufacturing errors in the sensor are characterized. If these measurement errors are not eliminated, the sensors would result in the host vehicle's assumed position rapidly diverging from its true position. Once the errors are characterized, they can be removed from the sensor output to improve the accuracy of the complete navigation system. The class of the sensor is determined by the amount of residual errors and the smaller the residual errors, the more expensive the sensor. The specific focus of the study is to determine whether it is possible to reduce the calibration cost of the Fiber-Optic Gyroscopes through the use of innovative calibration strategies. The use of neural networks are investigated as an alternative to the traditional calibration strategies which consists of the estimation of the constant error parameters through stochastic estimation strategies such as Kalman filters. The whole calibration problem is recast into the well-defined Systems Identification (SID) domain where the whole calibration problem is considered in terms of the systems identification design steps. The main contributions presented in this study are that the traditional calibration strategy is reviewed by casting the calibration problem into the Systems Identification domain; that a unified FOG error model is developed that combines a number of seemingly contradictory error models available in the technical literature; that computational intelligence techniques are used to perform gyro calibration; that a novel, non-linear gyro calibration strategy is developed; and that the sensors are calibrated under the simultaneous dynamic excitation of the full range of multi-dimensional environmental conditions. In the process of the development of this new calibration strategy the need for a problemspecific Criterion of Fit was observed. Such a Criterion of Fit was therefore developed and it acted as the core criterium whereby the accuracy of the new calibration strategy was assessed. One of the most important results obtained from the research presented in this thesis is that the new strategy significantly outperforms the traditional strategies and that, with the availability of high-performance embedded computational platforms, it has potential to be used within an operational environment as the gyro compensation strategy of choice.

The objective of this dissertation is to enhance the functionality of an existing simulation package that is used to simulate fiber optic networks. These enhancements include the capability to simulate protection mechanisms following link failure, which is a necessity in real-world optical networks to ensure the continued flow of information following a failure in a part of the network. The capability for network traffic to choose from additional paths is also an addition to the software. The enhanced, as well as the original simulation software, are open source: this allows anyone to freely modify and improve the source code to suit his or her requirements. This dissertation will focus on mesh-based optical network topologies, which are commonly found in regional optical backbone networks, but which are also increasingly found in metropolitan areas. The regional networks all make use of wavelength division multiplexing (WDM), which consists of putting multiple different wavelengths of light on the same physical fiber. A single fiber breakage will therefore disrupt multiple fiber-optic connections. A fiber-optic network designer has to satisfy various conflicting requirements when designing a network: it must satisfy current and predicted future traffic requirements, it must be immune to equipment failure, but it must also be as inexpensive as possible. The network designer therefore has to evaluate different topologies and scenarios, and a good network simulator will provide invaluable assistance in finding an optimal solution. Protection and restoration need to be looked at in conjunction with routing and wavelength assignment (RWA), to ensure that resources in a network are used at maximum efficiency. Connection restoration time will also be looked at: this should be minimised to ensure minimal network downtime and ensuing loss of revenue. The chosen alternate connection path should also be as short as possible to minimise use of resources and maximise the carrying capacity of the network. Blocking probability (the inability to establish a connection due to a congested network) is a crucial factor and is also investigated. The topologies investigated in this dissertation consist of various mesh based real-world regional WDM fiber-optic networks. The impact of various link failures, the addition of additional alternate paths, as well as the effect of a protection mechanism on these topologies are also investigated. The proposed goals were all successfully achieved. The capability of simulating single as well as multiple link failures was introduced to the simulation package. The blocking probability of various network topologies was compared to each other in the presence of link failures. Success was also achieved in the introduction of a third alternate path to the simulation package. / Dissertation (MEng(Electronic))--University of Pretoria, 2005. / Electrical, Electronic and Computer Engineering / unrestricted

We combine the evanescent field (EF) sensing mechanism with the fiber loop ringdown (FLRD) sensing scheme to create FLRD-EF sensors. The EF sensor heads are fabricated by etching the cladding of a single-mode fiber (SMF), while monitoring the etching process by the FLRD technique in real-time, on-line with high control precision. The effect of the sensor head dimensions on the sensors' detection sensitivity and response time are investigated. The EF scattering (EFS) sensing mechanism is combined with the FLRD detection scheme to create a new type of fiber optic index sensor. The detection limit for an optical index change is 3.2×10-5. This is the highest sensitivity for a fiber optic index sensor so far, without using any chemical-coating or optical components at the sensor head. A new type of index-based biosensor using high sensitivity FLRDEFS technique to sense deoxyribonucleic acid (DNA) and bacteria (Escherichia coli) is created.