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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

ALTERNATE FUELS FOR ON-ROAD ENGINES AND IMPACT ON REDUCING CARBON FOOTPRINT

Vrushali Satish Deshmukh (11198994) 02 August 2021 (has links)
Variable valve actuation remains one of the most studied technologies for diesel engines for fuel benefits, efficiency improvements and emission control. The same can be implemented on natural gas engines however presence of throttle valve in the spark ignited natural gas engine leads to different set of challenges and outcomes. In this document, focus is on GT power led analyses for a mid-range natural gas engine and the VVA strategy applied is modulation of intake valve closure timing. The simulations are run for early intake valve closure and late intake valve closure, both applied independently and run for steady state conditions. The focus is on the low torque range to study the impact of IVC modulation on throttling losses for low torque region. The simulation studies showed that IVC strategies both early as well as late IVC do benefit in terms of thermal efficiency improvements by up to 3% and reduction in brake specific fuel efficiency by up to 13%.It also showed considerable reduction in pumping loop and increase in open cycle efficiency when IVC modulation is applied. Validating the model further with real on-engine data and then calibrating the existing GT power with the on-engine data to validate the conclusions drawn would be the next set of goals for this project.<div><br></div><div>Second part of this document is focused on real life testing of soy biodiesel fueled heavy duty on-road engine with modern exhaust aftertreatment system with SCR. Soybean based biodiesel remains one of the most sought-after alternate fuel and biofuel to be used in on-road engines. Burning biodiesel leads to a cleaner exhaust compared to conventional diesel as the biofuel is oxygenated fuel leading to more complete combustion and lower amount of emission species such as CO, CO2and PM in the exhaust. The experiments discussed in this document consisted of developing torque curve envelopes and steady state tests (RMC set points). Three soy biodiesel blends were studied which included B20-20% biodiesel, B50 –50% biodiesel and B100 –100% biodiesel. NOx emissions were observed to be considerably higher for B100 at engine outlet by up to80% as well as at tailpipe outlet increased by up to380%, compared to that of conventional diesel which is attributed to the thermal mechanism of NO production. The exhaust gas temperatures were observed to be lower by up to40-degreeC while the urea dosing was considerably higher by up to83% when using biodiesel blend B100.Thisresearch paves the way to testing further using varying biodiesel blends for regulation certification trials, for tuning the diesel engines for different biodiesel blends and for developing the control strategy for the existing diesel engines to accommodate biodiesel.<br><div><br></div></div>
32

A Mixed-Methods Study of Alternate-Route Teachers' Effect on Student Learning

Spearman, Cassandra Faye 01 January 2017 (has links)
Due to teacher shortages at the study site, teaching positions in the state that is the focus of this study are filled by alternate route (AR) teachers, who earned bachelor degrees in the fields that were not related to education and received teacher certification through alternative teacher education programs. Because there is limited information about the preparation and performance of AR teachers at the site of this study, the purpose of this sequential mixed methods project study was to explore AR teachers' preparation and their effect on student learning as measured by Northwest Evaluation Association's Measures of Academic Progress/Discovery Education Assessments. Guided by Mezirow's experiential learning theory and Dewey's educational philosophy, this project study investigated the relationship between the alternate route teachers' field experiences and years of experience, and teachers' effect on student learning. Data collection included a survey of 36 K-12 AR teachers selected through convenience sampling, document analysis of their student assessment scores, and 6 structured interviews with purposefully selected high performing AR teachers. Data were triangulated and cross-analyzed. Findings indicated that when AR teachers engage in field experiences prior to teaching, their students have higher levels of achievement as evidenced in their assessment scores. There was no correlation between AR teachers' years of teaching experience and their student assessment scores. Analysis of AR teachers' interview responses revealed a need for professional development, which was then created to address those needs. This study may contribute to social change by offering the targeted professional development of AR teachers and improving the design of AR preparation programs to better influence student learning.
33

Genetic and morphological comparisons within the orthopteran family Pneumoridae

Laubscher, Maxine January 2019 (has links)
>Magister Scientiae - MSc / Bladder grasshoppers belong to the order Orthoptera, ancient family Pneumoridae and Superfamily Pneumoroidea. This small group of grasshoppers are sound producing, nocturnal, herbivorous grasshoppers endemic to the coastal regions of southern Africa. Very little genetic work has been done on these grasshoppers, and there is some taxonomic confusion regarding the validity of some species descriptions. The aim of this study was to provide much needed clarity on the true taxonomic diversity and polymorphic attributes within the Pneumoridae, focusing on selected taxa of uncertain status. Bladder grasshoppers show distinct discontinuous polymorphism, resulting in two clearly different male morphs utilizing two different mating strategies. Primary males make use of acoustic communication for mate location. Secondary males (alternate males) are significantly smaller and employ a “sneaker” or satellite strategy where they exploit the calling between duetting couples to locate the females before the primary male. Three species of bladder grasshoppers have been described (Parabullacris vansoni, Paraphysemacris spinosus and Pneumoracris browni) that only have an alternate male morph. The validity of these species descriptions has come into question with the discovery of alternate male morphs in at least three other species (Bullacris discolor, B. membracioides and B. obliqua). Thus, the species described by Dirsh (1963) may simply be alternate males of existing species. However, to date there have been no studies looking at the genetics of alternate males, which would definitively establish whether they are conspecific with primary males.
34

The response of river bar topography to the hydrological flow regime

Carlin, Mattia 21 July 2021 (has links)
Alternate bars are large-scale bedforms characterised by an ordered sequence of scour zones and depositional diagonal fronts alternating along channel banks, which are typical of straight channelized rivers. Due to their high relief and migration properties, they represent a problem in river management, because they affect navigation, increase the flooding risk and interact with instream structures. For this reason, in the last decades many studies took the challenge of defining suitable criteria able to describe their morphometric properties. Theoretical, experimental and numerical works have clearly demonstrated that bar occurrence is a threshold process governed by the width-to-depth ratio of the channel, β. If this parameter exceeds a critical threshold, βcr, an instability mechanism amplifies the riverbed perturbations occurring due to the effect of the turbulent flow on the cohesionless riverbed, leading to the spontaneous growth of finite amplitude bars. Under steady flow conditions, alternate bars achieve an equilibrium configuration, whose amplitude value is related to the difference β-βcr. Much less information is available to describe bar characteristics under variable flow conditions, when the width-to-depth ratio changes in time and the amplitude of bars evolves depending on the duration and the shape of the hydrograph. The effect of a single idealized flood on bar amplitude evolution was successfully described by the weakly nonlinear model of Tubino (1991), which was able to capture the trajectory of bar amplitude during different stages of the flood. Supported by experimental results, he found that the response of bars crucially depends on the ratio between the flood duration and the bar-growth timescale. Nevertheless, the effect of a complex flow regime, characterised by a sequence of flow events, is to a large extent unexplored. Specifically, (i) the definition of a criterion to predict the average response of alternate bars in a river reach subject to an hydrological flow regime and (ii) the quantification of bar amplitude evolution due to a complex flow regime are still to a large extent unexplored. The goals of this work are: (i) to investigate the dependence of bar properties to variable discharge conditions; (ii) to analyse the effect of flow unsteadiness in terms of duration and sequencing of flood events and derive the main hydrological characteristics that primarily control the average response of bar amplitude; (iii) to determine the long-term bar geometry and define the "bar-forming'' discharge, which is the theoretical discharge that if maintained indefinitely would produce the same long-term bar response as the natural hydrograph; (iv) to analyse the effect that a sequence of flood events composing a complex flow series has on the evolution of bar amplitude. To pursue these purposes, we adopted a methodology primary based on theoretical models, then supported and validated through the analysis of laboratory experiments and field data. The methodology and the key results for the different parts of this thesis can be summarized as follows: 1. First, the response of bar topography to different flow stages has been investigated both theoretically and through the analysis of experimental data, observing the dependence of alternate bars to peculiar threshold conditions. The validity of weakly nonlinear model of Colombini et al. (1987), originally defined in the neighborhood of the critical condition βcr, has been extended taking into account the emersion of bars for low flows. 2. Subsequently, the average response of bars to idealized flow series has been analysed, exploring their dependence on the duration and sequencing of flood events. The probability density function has been found to be the essential hydrological information of the flow series required to determine the long-term response of bar amplitude, while the integral scale of flow sequence is a suitable metric to quantify the unsteadiness of a flow regime. 3. Then, an innovative approach has been introduced to define an occurrence criterion for alternate bars in straightened river reaches that accounts for the hydrological regime, and to determine the average bar state, with the corresponding "bar-forming'' discharge. The key novelty with respect to the classical methods adopted so far to predict the long-term equilibrium channel geometry is that in this case the morphodynamical work acted on river bars by relatively low-flow stages enhancing their formation can be reversed by high-flow stages that suppress them. Therefore, both the occurrence criterion and the average state are found from a balance between the cumulative effects of bar-forming and bar-suppressing events. 4. Finally, the weakly nonlinear model of Colombini et al. (1987), originally defined to predict the evolution of bars under steady flow conditions, has been extended to reproduce a natural flow series by considering the basic flow varying in time. This approach allows us to (i) statistically investigate the effect of flood magnitude and duration on the variations of bar amplitude and (ii) to simulate the morphological response of a river to alterations of the hydrological regime.The long-term analysis of bar amplitude, as such as its evolution subject to the hydrological flow regime, have been applied to four different study cases, each of them characterised by a distinctive average bar response: two reaches of the Alpine Rhine River, upstream and downstream the confluence of the River Ill (Switzerland), respectively, the Adige River near Trento (Italy) and the Isère River near Montmèlian (France). The theoretical model is able to capture both qualitatively and quantitatively the observed bed response. Specifically, it predicts the occurrence of high-relief bars for the upstream reach of the Alpine Rhine River and for the Isère River, while a plane configuration is predicted for the Adige River. Also the intermediate response of the downstream reach of the Alpine Rhine River is reproduced, showing a predominant flat bed morphology with sporadic low-relief bars.
35

Early retention in rural schools: Alternate route teachers' perspectives

Jordon, Autumn K 09 August 2019 (has links)
The purpose of this qualitative study was to examine teachers' perspectives of the key factors contributing to the retention of rural teachers who entered teaching through an alternate route certification program in Mississippi. It was specifically the goal of this study to understand how alternatively certified teachers perceive their own characteristics (e.g., teacher preparation, personal experiences), school conditions (e.g., students, administration), and compensation (e.g., salary, benefits) to be related to their decision to remain in the profession. In this study, 9 rural alternate route teachers were interviewed from 8 schools in Mississippi. The research questions were: (1) How do rural alternate route teachers who stay describe their decision to continue teaching in terms of teacher characteristics?; (2) How do rural alternate route teachers who stay describe their decision to continue teaching in terms of school conditions?; and (3) How do rural alternate route teachers who stay describe their decision to continue teaching in terms of compensation? Sher's (1983) rural retention 3 C's framework provides a model for understanding retention. Sher proposed that attracting and retaining teachers in rural schools is a function of 3 C's: teacher characteristics, school conditions, and compensation. The data revealed that for teacher characteristics teacher preparation that included practice teaching combined with coursework was important, and participants valued experience working/teaching children. Data also revealed school conditions factors as student were a source of satisfaction for teachers, most teachers had little induction and mentoring support, teachers lacked administration and collegial support, and teachers found networks of support outside the school setting. The data revealed that the relationship between compensation and retention is complex, and that compensation was less important than intangible benefits. Although the study failed to find a simple and direct cause of retention, these findings do provide further insight into teacher retention. The findings of the study suggest implications for teacher preparation, school districts, and policy.
36

Simulation Evaluation of Measurement-based Automatic Dependent Surveillance -Broadcast

Vana, Sudha 12 June 2014 (has links)
No description available.
37

Design of a Configurable Alternate Fuel Injection Controller

Dagenais, Kevin 03 May 2005 (has links)
<p> This thesis presents a strategy for documenting real-time control systems, and the work products that result from its application to the development of an alternate fuel injection controller. In doing so, this document contributes technically to the areas of automotive control, and control systems documentation. The strategy was not developed independently of the control system, but in a manner which reflects its size and complexity.</p> <p> The controller is used to generate and transmit appropriately timed and sized pulses to an alternative fuel injector array, and switch auxiliary devices including a fuel heater, and an injector lock-off. Such a controller, when used to inject natural gas or propane into a gasoline burning engine, provides a reduction in both engine operating costs and harmful engine emissions.</p> <p> The controller stores a fuel map that relates the amount of energy released by the combustion of petroleum to that released by the combustion of an alternate fuel, over a range of varying environmental conditions. The fuel map is used to calculate the length of alternate injection pulses. These maps have been designed by, and are the property of Cosimo's Garage Ltd. and thus will not appear in this document.</p> <p> At present, nearly all large engine car conversion technology is more rigid than the solution provided here. Conversion costs are often prohibitive and problems requiring professional service are frequent. Should the controller described here, help to curb conversion costs and reduce the need for frequent service as is expected, the controller will be a viable candidate for production and sale.</p> / Thesis / Master of Applied Science (MASc)
38

THE CHALLENGE OF ALTERNATE LEVEL OF CARE (ALC) FACING OLDER ADULTS IN ONTARIO: IMPLICATIONS FOR GOVERNMENT AND POLICY MAKERS USING A DESCRIPTIVE DATA ANALYTICS APPROACH

Ahmed, Didi January 2019 (has links)
Introduction: Alternate Level of Care (ALC) patients are those who are kept hospitalized although they are medically well enough to be discharged. Those patients wait in acute care because they cannot access an appropriate alternative level of care outside the hospital. ALC leads to the improper consumption of valuable resources that are needed for patients waiting in other departments such as emergency rooms. This reflects poor quality outcomes of the healthcare system and represents a significant economic burden. Moreover, particularly when it concerns older adults, longer stay in hospital results in worsening their health outcomes, declining their functional status and increasing their needs for long-term care. Therefore, ALC is costly from both patient and health care system perspective. Objectives: The main objective of this study was to assess the impact of the Home First strategy on the incidence of ALC. Moreover, the study addressed both the specialized clinical needs (such as dialysis, chemotherapy and mechanical ventilation) and socioeconomic status of ALC patients in order to unveil their association with the ALC length of stay. Methods: This study involved a secondary analysis of data from the Institute for Clinical Evaluation (ICES). The analyzed dataset included a cohort of 6,059,033 hospitalization records of Ontario citizens, aged 65 years and older, who were admitted to an acute care facility between April 2004 and March 2017. The study involved descriptive analytics grouping the dataset into ALC and non-ALC subsets and examined the percentage of ALC hospitalizations, ALC days and reported odds ratios across several patients' characteristics. Results: From 2004 until 2016, ALC patients waited to access an appropriate destination for 10.7 million days. Those numbers represented 19.7% of all hospitalization days across Ontario. ALC was more likely among seniors aged 75-84 (OR 1.36, 95% CI 1.35-1.36), aged 85-94 (OR 2.16, 95% CI 2.15-2.17), aged 95+ (OR 2.46, 95% CI 2.40-2.50), females (OR 1.37, 95% CI 1.35-1.36), those who were hospitalized 90 days prior to their current admission (OR 1.22, 95% CI 1.21-1.22), and those who were admitted to hospital through Emergency Department (OR 2.64, 95% CI 2.62-2.67). Moreover, ALC was 10 times more likely in the subgroup of patients who were discharged to long-term care (LTC) (OR 9.71, 95% CI 9.66-9.77). For the socioeconomic characteristics, this study showed that patients were more likely to have ALC days when they lived in urban areas, had a lower income, and were highly unstable and dependent. Furthermore, patients with special clinical needs spent from 10% to 25% of their total hospitalization length of stay waiting to be discharged to an appropriated alternative level of care. Finally, the study revealed that although the implementation of a Home First strategy resulted in a 26% reduction of ALC hospitalizations and a 13% decrease in ALC days, the percent of patients discharged to LTC did not change. For the subgroup having the highest percentage of ALC hospitalizations (53.4%) and ALC days (40.3%), this reflects a partial failure of the Home First strategy in achieving its main objective of facilitating the discharge of patients to their homes. Conclusions: Policy makers and health care practitioners may benefit from the findings of this study by considering the needs of the ALC patients while planning, allocating resources, and developing polices for discharge, LTC and community care. However, more work is required to quantify the impact of the ALC determinants suggested in this study and assess the efficiency of the current policies and procedures. Introduction: Alternate Level of Care (ALC) patients are those who are kept hospitalized although they are medically well enough to be discharged. Those patients wait in acute care because they cannot access an appropriate alternative level of care outside the hospital. ALC leads to the improper consumption of valuable resources that are needed for patients waiting in other departments such as emergency rooms. This reflects poor quality outcomes of the healthcare system and represents a significant economic burden. Moreover, particularly when it concerns older adults, longer stay in hospital results in worsening their health outcomes, declining their functional status and increasing their needs for long-term care. Therefore, ALC is costly from both patient and health care system perspective. Objectives: The main objective of this study was to assess the impact of the Home First strategy on the incidence of ALC. Moreover, the study addressed both the specialized clinical needs (such as dialysis, chemotherapy and mechanical ventilation) and socioeconomic status of ALC patients in order to unveil their association with the ALC length of stay. Methods: This study involved a secondary analysis of data from the Institute for Clinical Evaluation (ICES). The analyzed dataset included a cohort of 6,059,033 hospitalization records of Ontario citizens, aged 65 years and older, who were admitted to an acute care facility between April 2004 and March 2017. The study involved descriptive analytics grouping the dataset into ALC and non-ALC subsets and examined the percentage of ALC hospitalizations, ALC days and reported odds ratios across several patients' characteristics. Results: From 2004 until 2016, ALC patients waited to access an appropriate destination for 10.7 million days. Those numbers represented 19.7% of all hospitalization days across Ontario. ALC was more likely among seniors aged 75-84 (OR 1.36, 95% CI 1.35-1.36), aged 85-94 (OR 2.16, 95% CI 2.15-2.17), aged 95+ (OR 2.46, 95% CI 2.40-2.50), females (OR 1.37, 95% CI 1.35-1.36), those who were hospitalized 90 days prior to their current admission (OR 1.22, 95% CI 1.21-1.22), and those who were admitted to hospital through Emergency Department (OR 2.64, 95% CI 2.62-2.67). Moreover, ALC was 10 times more likely in the subgroup of patients who were discharged to long-term care (LTC) (OR 9.71, 95% CI 9.66-9.77). For the socioeconomic characteristics, this study showed that patients were more likely to have ALC days when they lived in urban areas, had a lower income, and were highly unstable and dependent. Furthermore, patients with special clinical needs spent from 10% to 25% of their total hospitalization length of stay waiting to be discharged to an appropriated alternative level of care. Finally, the study revealed that although the implementation of a Home First strategy resulted in a 26% reduction of ALC hospitalizations and a 13% decrease in ALC days, the percent of patients discharged to LTC did not change. For the subgroup having the highest percentage of ALC hospitalizations (53.4%) and ALC days (40.3%), this reflects a partial failure of the Home First strategy in achieving its main objective of facilitating the discharge of patients to their homes. Conclusions: Policy makers and health care practitioners may benefit from the findings of this study by considering the needs of the ALC patients while planning, allocating resources, and developing polices for discharge, LTC and community care. However, more work is required to quantify the impact of the ALC determinants suggested in this study and assess the efficiency of the current policies and procedures. / Thesis / Master of Science (MSc)
39

Breaking the Time Barrier: Algebra Instruction in an Alternate-Day Block Schedule

Wright, Vella S. 30 April 1998 (has links)
Over half of the high schools in Virginia utilized a block schedule in 1996-97. With an extended block of time, teachers have the opportunity to vary instruction to incorporate a range of strategies to enhance student engagement and increase student achievement. The purpose of this study is to provide a detailed description of algebra instruction in an extended alternate-day block schedule. Using case study methodology, data were gathered from six algebra teachers' classrooms. Data sources included multiple classroom observations, teacher interviews, surveys, and a review of students' final algebra grades. A case record was developed for each teacher and cross-case matrices were used to analyze the degree of teacher satisfaction with the block, teacher readiness to teach algebra in the block, the types of instructional strategies utilized in algebra lessons, the level of student engagement and achievement, and advice to others. Findings indicate that teachers viewed the planning process prior to implementation of the block schedule as inadequate. Teachers have utilized strategies including cooperative learning, student projects, and problem-solving with applications. They advise other algebra teachers confronting a block schedule for the first time to engage in activities prior to implementation, including researching alternative teaching strategies, designing and planning projects for students, finding applications, redesigning homework assignments, and purchasing hands-on materials and software. Teachers are concerned about student learning, especially for ninth graders, students who are math-anxious, or students who are frequently absent. It was concluded that, although the teachers had not actively participated in the decision to change to a block schedule, they have adjusted to the new schedule. Some now enjoy the block and others continue to be dissatisfied. Although the block offers time to incorporate a range of activities, the algebra teachers typically use a familiar three-part model of instruction (including a prompt focus, explanation with modeling, and time for practice and summarization.) Homework remains an essential feature of algebra lessons and teachers routinely allow students to use graphing calculators. Students' grades in algebra have not improved; the percentage of students failing algebra has increased slightly in the alternate-day block schedule / Ed. D.
40

A Standalone Wire Database for Routing and Tracing in Xilinx Virtex, Virtex-E, and Virtex-II FPGAs

Steiner, Neil Joseph 19 September 2002 (has links)
Modern FPGAs contain routing resources easily exceeding millions of wires. While mainstream design flows and place-and-route tools make very good use of these routing resources, they do so at the cost of very significant processing time. A well established alternative scheme is to modify or generate configuration bitstreams directly, resulting in more dynamic designs and shorter processing times. This thesis introduces a complete set of alternate wire databases for Xilinx Virtex, Virtex-E, and Virtex-II FPGAs, suitable for standalone use or as an addition to the JBits API. The databases can be used to route or trace through any device in these families, and can generate the necessary bitstream configurations with the help of JBits or an independent bitstream interface. / Master of Science

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