Thesis (M.Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 111-125) Also available in print.

Thesis (M. Phil.)--University of Hong Kong, 1998. / Includes bibliographical references (leaves 111-125).

Thesis (M.A.)--Brock University, 2005. / Includes bibliographical references (leaves 196-219). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (M.A.)--Brock University, 2005. / Includes bibliographical references (leaves 196-219)

D.Ing. / The technique of using a live power cable to simultaneously transport a communication signal, has been practiced since the early 1900’s. In most cases, power-line communications has been implemented as a retrofit technology, with its main benefit being the utilization of a ‘free’ existing network. This driving force of power-line communications is typical for high-, medium-, and low-voltage distribution networks, as well as intra-building networks currently targeted for home automation and home networking. Researchers have thus focused on the optimum use of these existing power-line channels, often accepting the inherent drawbacks of this hostile communication channel. Apart from unpredictable noise sources, two main disadvantages of the low-voltage powerline network as a communication channel, are i) the unknown power cable characteristics and topology and ii) time-dependent fluctuation of the power-line impedance level as loads are unpredictable switched into, and out of the network. These two factors have obscured the requirements for proper coupling and impedance adaptation to the degree that most researchers and manufacturers have merely accepted this typical ≈ 20-dB coupling loss as one of the inherited disadvantages of the power-line channel. Most researchers and manufacturers have thus defaulted to a guessed power-line impedance level, and have used one fixed coupler winding ratio under all circumstances, regardless of power-line conditions. This study has shown that proper coupling and impedance adaptation can yield significant transmission gains even with limited (qualitative) knowledge of a power-line channel and its topology. After formulating design steps for an impedance-adapting coupler that facilitates bidirectional transmission, the impact of the fluctuating power-line impedance on coupler bandwidth was investigated. Next, impedance adaptation strategies were considered and the tradeoff between series cable requirements and parallel load requirements was explored. A model of sufficient simplicity was developed to facilitate qualitative description and classification of power outlets – functioning as communication nodes. Very interesting simulation results were obtained and these were verified using a laboratory setup of characterized power cables and calibrated loads. Next, these simulation results were employed to improve power-line transmission over a live, uncharacterized 220-V residential network by means of i) classifying typical residential rooms qualitatively in order to choose proper coupler winding ratios and ii) using an innovative dual coupler for dedicated on-off switching with harsh loads, thereby mitigating the fluctuating impact of said loads on low-voltage power-line communications.

Access to adequate liquidity to finance future investments is an essential element of financial management. The two main questions that this dissertation attempts to answer are (i) what is the net valuation effect of LoC? and (ii) if LoC create value, what are the sources of this value? To answer these questions, I constructed a sample of 85,232 firm-years spanning from 1993 to 2016, with credit line data obtained from Capital IQ and Bloomberg. I investigated the valuation effects of LoC with a methodology extensively used in the analysis of the valuation implications of cash. I used this methodology because cash and LoC are two alternatives to manage liquidity and estimated the changes in shareholders' value associated with changes in existing LoC undrawn balances and on new LoC agreements. The results from this analysis demonstrates a positive association between increases in LoC capacity and shareholder's value. These findings are also obtained in univariate and event study analyses. The results also suggest that LoC create more value for firms that are rich in cash, indicating the LoC and cash are complementary liquidity management tools. I then focused on the sources of the value created by credit lines. I examined whether information asymmetry plays a role in LoC valuation by analyzing the association between firm value and LoC for firms with high- and low-information asymmetric. I also studied whether LoCs reduce agency problems by comparing firm value and LoC capacity in both poorly and well-governed firms. Furthermore, I examined whether firms benefit from an increase in financial flexibility provided by access to credit lines. I found results consistent with LoC being more valuable for firms with higher levels of informational asymmetries. The analysis also suggests that LoCs with longer maturity create more value than those with shorter maturity. Surprisingly, I find limited support for the hypothesis that shareholders place a higher value on LoCs in increasing financial flexibility. Moreover, I found no support for the role of credit lines in reducing agency problems.

M.S.

Transverse radiopaque lines, often referred to as transverse lines (TL's), are a type of hard-tissue pathology which develop in subadult long bones after episodes of nonspecific stress such as nutritional or metabolic insult. This pathology is well documented in archaeological contexts and is used as a tool for making paleo demographical inferences about the general health of populations. Stable isotope studies have suggested that early modern humans were exploiting a wide range of dietary resources by the mid-Upper Paleolithic, while Neandertals appear to have utilized a narrower spectrum of resources, expending more energy on large game. This may have been a significant factor in differential survival success, frequency of transverse line formation, and age of initial transverse line formation. Because archaic humans may have been more susceptible to seasonal resource fluctuations, they may have suffered increased nutritional and metabolic stress compared to early modern humans. This study evaluates differences in the frequency and timing of initial transverse line formation among archaic, early modern human, and recent human (Holocene) subadult populations. Radiographs of the tibial distal shafts of 200 archaic, early modern humans, and recent modern humans were scored as displaying or not displaying TL's. TL's were counted, and age-at-formation was calculated. Kruskal-Wallis nonparametric tests were used to compare the frequency of occurrence of TL's and age-at-formation among the three groups. Results indicate that both archaic and early modern humans exhibited less transverse lines than the recent human group. This may be related to sampling bias in the recent human dataset. There is no difference in the number of transverse lines among the recent human samples, and it seems possible that all three of the recent human populations sampled for this study were experiencing high levels of stress. Thus, it seems that for the archaic and early modern human groups, transverse line formation may have been more closely related to differences in subsistence strategies, while transverse line formation in the recent human group may have been more closely related to high frequencies of metabolic diseases and poor diet. Further analysis revealed that archaic humans developed their first transverse lines earlier in life than both early modern and recent modern humans. The age at first line formation is frequently related to weaning age in studies of archaeological population, and this (and other possible explanations) are evaluated relative to Late Pleistocene Neanderthals and early modern humans.

published_or_final_version / Electrical Engineering / Master / Master of Science in Engineering

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