VictorJuiz/thesis huggingface dataset:
Real-time digital simulation of switching power circuits

Sophisticated power electronic apparatus and their digital control systems are finding increasing applications in electric power systems at generation, transmission, distribution and utilization levels. It is essential to carry out rigorous performance evaluation of the power electronic equipment and their digital controllers prior to their commissioning on the host power system. The current trend to achieve that goal is to interface a real-time digital simulator representing the power electronic apparatus and the host power system with the digital controller. This thesis addresses the issue of synchronization between the output signals of the digital controller for firing power electronic switches and the discrete time-step of the real-time simulator. It is shown that lack of such synchronization can lead to severe inaccuracies in the simulation results. A novel real-time simulation algorithm is proposed for accounting incoming switching events in fixed step-size digital simulation. This algorithm relies on the registration of the timing of the switching events and a subsequent correction procedure to calculate the system state. Off-line time domain simulations of a Pulse Width Modulated (PWM) Voltage Source Inverter (VSI) system demonstrate a ten-fold improvement in accuracy of the proposed algorithm over the fixed step-size algorithm using the same step-size. Practical feasibility of the proposed algorithm is demonstrated by implementation on a digital computing platform comprising of a DSP and a FPGA. The hardware and software design process follows a modular approach which makes it amenable for implementation on next generation processors. A 5kVA experimental set-up of the PWM VSC system is used to verify the results of the real-time simulation.
Measurement of microvascular blood flow in skin and skeletal muscle using ultrasound contrast agents and a negative-bolus indicator-dilution technique

'Introduction'. Clinical measurement of blood flow at the capillary level remains a challenging problem. The introduction of microbubble contrast agents and their specific ultrasound detection schemes may make measurements at this vessel level possible. We describe a method for quantitative microvascular blood flow measurement, utilizing ultrasound imaging and microbubble contrast agents, with emphasis on application in reconstructive microsurgery. The method is tested in bench-top phantoms, and an in-vivo model of skin perfusion. 'Methods'. Microbubble agents are inherently susceptible to disruption by high-power ultrasound pulses. Disruption was combined with ultrasound imaging to measure flow based on indicator-dilution theory. Implementation on a clinical scanner allowed in-vitro testing in vessel phantoms (7mm and 100[mu]m diameter) while in-vivo measurements were done on a porcine skin model and compared to results obtained by radioactive microsphere injection. 'Results'. In-vitro, ultrasound flow measurement and actual flow were found to be well correlated ('r' = 0.98), while in-vivo good agreement was also found between the ultrasound technique and microsphere injection ('r' = 0.78).
Local conditions affecting the implementation of a school council governance plan

Mandating school councils by the school board under study signaled the introduction of significant change in its organizational structure from one predominantly characterized by central control over its schools, to one in which a higher degree of parental and community involvement was expected at the local level. This devolution can be compared to a process of emancipation, in that schools were expected to become more reliant on their own resources and less dependent on the established organizational superstructure, especially with regard to resolving issues put before them by their school and its community. The purpose of this study was to seek out conditions and key variables affecting school council policy implementation from the perspectives and performance of school council members and key informants and to explore the emancipation process which ensued. The study employed qualitative research methodology, in particular the case study method. Representative members from each of three selected school councils were interviewed and their activities observed during school council meetings in the period September 1995 to May 1996. The thirty-three participants included the school principal, at least two parents and two teachers, a non-teaching staff member, and usually, a representative from the community or parish from each school council under study. In addition, six school board key informant interviews were conducted. The conceptual framework which guided the study was the policy implementation model developed by Carl Van Horn and Donald Van Meter (1977). The study also included document analyses of the school board policy development and adoption processes. The findings revealed that in introducing the school council policy the school board affirmed the concept that professionals, parents and other community members could be actively involved in the education of children, a significant change from their current practice. The use of a steering committee, made up of school system representatives and the increased community participation at the school level, shaped a collegial model for system policy implementation, and identified the key role the principal plays in policy implementation. Generally, implementation was viewed as an evolutionary, contextual process contingent on local needs and resources. The evolution of the school councils examined in this study might have occurred more expeditiously and effectively if the concept, operation and role expectations specific to council members had been better understood prior to implementation. However, it became evident during this study that school council participants could accommodate to the changes they experienced during the investigative process. School council needs identified in the study were ongoing training, and sustained, appropriate membership. Areas of future study include a school council focus on school effectiveness and learning services so that student learning is improved; a focus for Catholic School Councils on the distinctiveness and continuance of Catholic education.
Employment and wage dynamics, estimating the impact of labour market institutions

This dissertation is comprised of two separate empirical projects that focus on the effect of changes in the institutional environment--in China, the movement to a "market economy" and in Canada, changes in the minimum wage legislation--on employment and wage dynamics. 'Part I: Wage and employment determination in Chinese state-owned enterprises, 1980-1994'. Labour market reforms in transitional economies are especially important to the restructuring of state-owned enterprises (SOEs) because they not only affect production efficiency, but also have potentially adverse social impacts on urban unemployment and income inequality. Using an extensive establishment-level panel data, Chapters 1 to 3 present some of the first empirical evidence on how Chinese SOEs have changed their employment and wage setting behaviour in response to gradual decentralization. Despite the deep-rooted egalitarian culture, I show that the link between workers' pay and enterprise performance strengthened between 1980 and 1994. However, the effect of reform on employment decisions appears to have been much weaker. Employment adjustment to demand shocks did not increase over the slow rates of the early 1980s. More importantly, I find that the central planning model provides a more consistent interpretation of the observed employment patterns. These results suggest that the decentralization in Chinese labour market is heavily skewed towards wage determination. The government continues to play an important role in employment decisions at least until the mid-1990s. 'Part II: Minimum wage legislations in Canada, 1988-1990 '. Previous U.S. panel estimates of minimum wages effects on youth employment have been criticized on the grounds that their identification rests on comparisons of 'low wage' and 'high wage' workers, who may differ in ways besides their pay. The institutional structure of minimum wage laws in Canada, whereby minimum wages vary across provinces, permits an evaluation of this objection. Using individual-level panel data for 1988-90, empirical results in Chapter 4 appear to vindicate the critics: the estimates based on exclusive samples of "low wage" workers are small and statistically insignificant. Low wage workers, however, are in turn a heterogeneous group. For 'transitory' workers with less than 3 quarters of low wage employment in the sample period, the minimum wage effects are virtually zero. Yet, there is a significant disemployment effect for the complementary group.
Parapegmata, or, astrology, weather, and calendars in the Ancient World, being an examination of the interplay between the heavens and the earth in the Classical and Near-Eastern cultures of antiquity, with particular reference to the regulation of agricultural practice, and to the signs and causes of storms, tempests, &c

I examine a set of texts and instruments, called 'parapegmata ', which were used in the classical world for tracking cyclical phenomena such as stellar phases, weather, hebdomadal cycles, lunar cycles, and more. I argue that these texts are primarily astrological rather than astronomical or calendrical. I trace the possible connection between parapegmata and calendrical cycles in Greece, Rome, and Babylon, but I maintain a sharp distinction between calendars and parapegmata: the parapegmata were not used for chronological purposes, but rather for the regulation of various activities, most prominently agriculture. Different types of parapegmata were used by the Greeks and Romans for tracking stellar and lunar phenomena, and these distinct phenomena were used by them as signs for the timing of various activities, partly in an attempt to align their actions with sympathetic forces in the Cosmos. In order to understand how the parapegmata were used, I devote a chapter to unraveling the modes of predictive signification in the parapegmata, showing how these texts and instruments eliminated the need for astronomical observation. I show that some similar astronomical phenomena were tracked by the Babylonians and Egyptians for similar purposes, although the parallels we find in these cultures show a much closer connection to other, more diverse types of omina than the classical texts do. The work includes a descriptive catalogue of all the parapegmata known to me.
Metallurgical and mechanical properties of Ni-based superalloy friction welds

Friction welding is a solid state joining process and can be used to successfully join similar and dissimilar Ni-based superalloy base materials. The objective of this project involves the optimization of welding parameters and post weld heat treatment procedures during similar Ni-base wrought alloy and dissimilar (Ni-base wrought alloy/Ni-base cast alloy) friction welding. Extensive microstructural analysis was carried using a combination of optical, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The application of a [re-solution + stabilization + precipitation] post weld treatment procedure produced the optimum balance of joint tensile strength and ductility properties in Ni-base wrought alloy friction joints. TEM analysis provided an insight concerning the various mechanisms that occur in friction welded joints, particularly with regard to changes in precipitate chemistry and in particle distributions.
The role of hydrogen peroxide in the resistance of tomato to penetration by Colletotrichum coccodes

The accumulation of reactive oxygen species and subsequent effects were investigated in the interaction between 'Colletotrichum coccodes', causal agent of anthracnose, and tomato cotyledons. After initiation of penetration the fungus enters a quiescent stage and does not immediately colonize the host. Hydrogen peroxide (H2O2), localized with diaminobenzidine, accumulated at sites of attempted fungal penetration. In contrast, superoxide was not detected at these sites as visualized by nitroblue tetrazolium. Injection of catalase or ascorbic acid into tomato cotyledons prior to inoculation, to reduce H2O2 accumulation, significantly increased the frequency of fungal penetration (48 hpi) by the pathogen 'C. coccodes ', but not the non-pathogen 'C. lagenarium'. In the host interaction, H2O2 accumulation was associated with cross-linking of cell wall proteins at sites of attempted penetration. Transcription and translation inhibitor treatments did not increase fungal penetration, supporting a role for oxidative cross-linking as a resistance mechanism in this interaction.
The relationships among the effect of carbohydrates on blood glucose, appetite, food intake, mood and memory

The hypothesis of this research was that there is a relationship between the effect of carbohydrates on blood glucose and their effects on appetite, food intake, mood and memory. Experiment 1 examined the effects of 300kcal preloads of sucrose, polycose, amylose and amylopectin on blood glucose over one hour. Experiment 2 examined the effect of the same treatments on appetite, food intake, mood and memory. The final experiment examined the relationships among the glycemic response to sucrose, polycose, glucose, fructose/glucose mixture and sucralose preloads and their effects on appetite, food intake, mood and memory. A relationship was observed between the high glycemic carbohydrates, sucrose, polycose and glucose and decreased mealtime energy intake at one hour. No relationship was found between the glycemic response to carbohydrates and mood and memory. Sucrose preloads were found to improve memory performance. It is concluded that the glycemic response to carbohydrates is associated with their effect on appetite and food intake but not mood and memory.
The influences of teacher leadership style on students' affective motivation

This study utilized students' perceptions to understand how teachers as managers of culturally diverse classrooms may utilize a leadership style that enhances students' affective motivation. Data was obtained from 68 students who came from 43 schools. Evidence from this study shows that teacher consideration, student learning self-concept, peer relations, student ethnicity, and the interaction effects of student ethnicity and teacher consideration are significant predictors of student affective motivation (R2 = 0.85). Students of Asian heritage perceived a teacher leadership style that was characterized as having the best teacher-student relationships and reported the highest levels of affective motivation. Conversely, students of African heritage perceived a teacher leadership style that was characterized as having the poorest teacher-student relationships and reported the lowest levels of affective motivation. The conclusion is that the use of a teacher leadership style that focuses on the development of good teacher-student relationships maybe an effective tool to enhance student affective motivation.
Proinsulin and changes in glucose tolerance in a native Canadian community experiencing an epidemic of type 2 diabetes mellitus

The objectives of this thesis were to (1) identify the distribution and determinants of proinsulin concentration in a Native Canadian population with high rates of obesity and glucose intolerance, and (2) assess the relationship between metabolic and lifestyle factors and change in glucose tolerance over a period of 4 years among individuals from this population who were at high risk for diabetes at baseline. High-risk subjects were defined as those with impaired glucose tolerance (IGT) or normal glucose tolerance (NGT) with an elevated post-challenge glucose concentration (>=7.0 mmol/l). The research was carried out using data from the cross-sectional (1993-1995) and prospective (1998) phases of a population-based study conducted in partnership with an isolated First Nation community in northern Ontario. In each phase, samples for glucose, insulin, C-peptide, lipids and proinsulin were drawn after an overnight fast, and percent (%) body fat, waist circumference and blood pressure were measured. Diabetes and IGT were diagnosed using standard criteria after a 75g oral glucose tolerance test. Information regarding parity and lifestyle risk factors was collected using standardized questionnaires. After adjustment for covariates including C-peptide, proinsulin concentration was significantly elevated in subjects with both diabetes and IGT compared to those with NGT, and proinsulin increased across the spectrum of NGT. Waist circumference and percent body fit were significantly positively associated with proinsulin concentration. In addition, both baseline and change in waist circumference were positively associated with follow-up concentrations and change in proinsulin. Nulliparity was associated with diabetes risk as well as insulin resistance and increased proinsuhn concentration. Proinsulin showed significant associations with concurrent concentrations of lipids in subjects with NGT. Further, elevated triglyceride and reduced high-density lipoprotein cholesterol concentrations were prospectively associated with follow-up and change in proinsulin concentration. Cigarette smoking, change in proinsulin and change in insulin resistance were prospectively associated with deterioration to diabetes. These results demonstrate that (1) proinsulin is an important indicator of the stage of diabetes pathophysiology, (2) proinsulin is associated with modifiable metabolic and lifestyle factors that may be indicative of elevated free fatty add concentrations, and (3) smoking and changes in beta cell function and insulin resistance are associated with diabetes risk.
Resource allocation and channel access control in multimedia wireless CDMA networks

Wireless communication networks have been growing rapidly in recent years. Future wireless networks will extend the services of existing wireless systems and provide a wide range of multimedia services to mobile users. Towards multimedia traffic transport over the shared radio channel, the choice of an appropriate Medium Access Control (MAC) protocol is of great importance. Future wireless networks will require a MAC protocol which allocates channel resources to multimedia services according to their Quality-of-Service (QoS) requirements. This thesis explores the issue of QoS provisioning for multimedia services in future wireless Code Division Multiple Access (CDMA) networks. Solutions to resource allocation and channel access problems are proposed which attempt to share radio resources among users in a fair and efficient manner. A framework is developed for QoS provisioning in CDMA systems in which the base station controls multiuser interference in each wireless cell. Using the concept of scheduling in Time Division Multiple Access (TDMA) systems, a hybrid CDMA/TDMA system is proposed in which access to channel resources in time and power domains is controlled by the base station. The resource allocation problem of the hybrid system is divided into power control and time scheduling problems. The power control problem is formulated and the optimum power level of each packet transmission is determined. The fair queueing concept is used to develop a resource allocation approach for the class of CDMA systems. A packet-based approximation of this approach is then presented as the time scheduling scheme of the hybrid system. The integration of time scheduling and power control schemes and the issue of service share assignment in the hybrid system are also addressed. Using the wideband CDMA technology, a system architecture is presented for the hybrid system. A MAC protocol is then developed for this system which employs a simplified version of our proposed scheduling scheme. Several signaling mechanisms are proposed which allow different mobiles to send scheduling-related control information to the base station. To demonstrate multimedia support capabilities of the hybrid system and examine the performance of proposed signaling mechanisms, simulations are performed with various mixes of multimedia services.
Behaviour of simple framing connections to partially concrete encased H section columns

Composite columns are increasing being used as the primary gravity load carrying elements in medium to high-rise construction. In an attempt to optimize the steel weight ratio there has been a new construction detail recently proposed, consisting of partially concrete encased steel WWF sections. The weak axis connection will be made to an end plate connecting the flange tips, and thus providing a terminus at the column face. This research examines the behaviour of simple framing connections to the weak axis of the proposed column. A total of 14 tests were conducted, with a variety of connection types and beam sizes. The main test variables included the connection type, the beam size and the size of the test column. Out of concerns for the stability of the columns during construction several tests were performed on the bare steel column to evaluate the influence of the locally introduced connection load on the overall column strength.
Anti-G suit inflation effects during low-intensity -/+ Gz maneuvers

'Purpose'. It was hypothesized that early initiation of G-suit inflation with increased pressure and rate would offer greater protection against the hypotensive response ("push-pull effect", PPE) resulting from -/+Gz transitions ("push-pull effect maneuver", PPEM) versus the existing inflation schedule. 'Methods'. Using a tilt table, subjects were rapidly tilted from HUT1 (15° from vertical; +1 Gz) to HDT (135°; -0.71 Gz for 15 secs) to HUT2 (15°, for 45 secs). Physiological measurements for 1 unprotected and 4 protection schedules were analyzed. 'Results'. All G-suit schedules maintained blood pressure suggesting inflation is an adequate protective measure during low-intensity PPEMs. Few statistically significant differences were observed between the protection schedules. 'Conclusions'. (1) G-suit inflation ameliorated the hypotensive response to the PPEM, (2) Results were not conclusive as to whether inflations of certain timing or pressure will further ameliorate this hypotensive response. An increased G-envelope and operationally proper inflation pressures are recommended for future investigations.