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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.
21

Reflectivity Measurement System Development and Calibration

Peng, Tao January 2007 (has links)
Accurate assessment of road luminance provided by overhead streetlights helps to optimize the visibility of objects on the road and therefore promotes driver safety, while minimizing energy consumption. To calculate road luminance, the road surface reflectivity has to be known. Odyssey Energy Limited has developed a prototype system that has the potential to determine the road reflectivity properties at high speed. In this thesis, an investigation into the prototype system has been conducted and further enhancement and redesign has been done. A portable on-site road surface reflectivity measurement system that complies with the Commission Internationale de I' Eclairage (CIE) standard was developed. The road test of this new system has been carried out on a series of Hamilton city roads. It proved that the new system is capable of measuring the road surface reflectivity and classifying the road into its appropriate R class according to the CIE standards specified in street lighting design criteria. Later the OEL prototype system was calibrated against the new system to find out the correlation between the two systems.
22

Linking Theory to Practice: Understanding How Two Reading Recovery Teachers' Reflections Inform their Teaching Practices

Mays, Lydia Criss 17 August 2009 (has links)
Using a grounded theory approach to investigate the multidimensional reflections of two Reading Recovery teachers, this inquiry responds to calls for research on reflection and provides information for the field of education in understanding the nature of teachers’ reflections and how they inform teaching practices. Reading Recovery is a progressive intervention program which brings the lowest performing readers and writers to average levels of achievement in twelve to twenty weeks through daily, thirty minute one-on-one tutoring sessions that follow the same lesson pattern daily. Reading Recovery teachers are carefully trained to use reflection to design, implement, and observe children’s reading and writing practices to accelerate their reading and writing skills. To investigate the nature of participants’ reflections and how those reflections informed their teaching practices the data sources, collected over eight weeks, for each participant included field notes from seventeen observations, two semi-structured interview transcripts, thirty-six course documents, and two member checks transcripts. Open coding, memoing, and axial coding were used to examine all data sources. Further, each of the three dimensions of reflection, time, type, and context, were accounted for to fully explore participants’ reflections. Three interrelated major themes connected to the nature of Reading Recovery teachers’ reflectivity and practice were identified: (1) participants’ reflections are situated within the contextual framework of Reading Recovery and inform practices by serving as a roadmap to scaffold individualized instruction and examine personal philosophies of teaching and instructional assumptions; (2) Teacher identity as a reflective practitioner is a natural outcome participants and fosters the interconnectedness of practice and automaticity in their reflective practices; and (3) Systematic observations of the child during instruction focus on actions of the child and themselves as a teacher and serve as a trigger for reflection in a data-driven response sequence linking theory to practice. This study offers insight into how reflective practices of teachers of reading may be fostered through teacher education and into their own teacher development by linking their theoretical perspectives to their teaching practices.
23

Hydrologic Validation of Real-Time Weather Radar VPR Correction Methods

Klyszejko, Erika Suzanne January 2006 (has links)
Weather radar has long been recognized as a potentially powerful tool for hydrological modelling. A single radar station is able to provide detailed precipitation information over entire watersheds. The operational use of radar in water resources applications, however, has been limited. Interpretation of raw radar data requires several rigorous analytical steps and a solid understanding of the technology. In general, hydrologists’ lack of meteorological background and the persistence of systematic errors within the data, has led to a common mistrust of radar-estimated precipitation values. As part of the Enhanced Nowcasting of Extreme Weather project, researchers at McGill University’s J.S. Marshall Radar Observatory in Montreal have been working to improve real-time quantitative precipitation estimates (QPEs). The aim is to create real-time radar precipitation products for the water resource community that are reliable and properly validated. The validation of QPEs is traditionally based on how well observed measurements agree with data from a precipitation gauge network. Comparisons between radar and precipitation gauge quantities, however, can be misleading. Data from a precipitation gauge network represents a series of single-point observations taken near ground surface. Radar, however, estimates the average rate of precipitation over a given area (i.e. a 1-km grid cell) based on the intensity of reflected microwaves at altitudes exceeding 1 km. Additionally, both measurement techniques are susceptible to a number of sources of error that further confound efforts to compare the two. One of the greatest challenges facing radar meteorologists is the variation in the vertical profile of reflectivity (VPR). A radar unit creates a volumetric scan of the atmosphere by emitting microwave beams at several elevation angles. As a beam travels away from the radar, its distance from ground surface increases. Different precipitation types are sampled at a number of heights (i.e. snow above the 0º C elevation and rain below it) that vary with range. The difficulty lies in estimating the intensity of precipitation at the Earth’s surface, based on measurements taken aloft. Scientists at McGill University have incorporated VPR correction techniques into algorithms used to automatically convert raw radar data into quantitative hydrological products. This thesis evaluates three real-time radar precipitation products from McGill University’s J.S. Marshall Radar Observatory in the context of hydrological modelling. The C0 radar product consists of radar precipitation estimates that are filtered for erroneous data, such as ground clutter and anomalous precipitation. The C2 and C3 radar products use different VPR correction techniques to improve upon the C0 product. The WATFLOOD hydrological model is used to assess the ability of each radar product to estimate precipitation over several watersheds within the McGill radar domain. It is proposed that using a watershed as sample area can reduce the error associated with sampling differences between radar and precipitation gauges and allow for the evaluation of a precipitation product over space and time. The WATFLOOD model is run continuously over a four-year period, using each radar product as precipitation input. Streamflow hydrographs are generated for 39 gauging stations within the radar domain, which includes parts of eastern Ontario, south-western Quebec and northern New York and Vermont, and compared to observed measurements. Streamflows are also modelled using distributed precipitation gauge data from 44 meteorological stations concentrated around the Montreal region. Analysis of select streamflow events reveals that despite the non-ideal placement of precipitation gauges throughout the study area, distributed precipitation gauge data are able to reproduce hydrological events with greater accuracy and consistency than any of the provided radar products. Precipitation estimates within the McGill radar domain are found to only be useful in areas within the Doppler range (120-km) where the radar beam is unobstructed by physiographic or man-made features. Among radar products, the C2 VPR-corrected product performed best during the greatest number of the flood events throughout the study area.
24

Hydrologic Validation of Real-Time Weather Radar VPR Correction Methods

Klyszejko, Erika Suzanne January 2006 (has links)
Weather radar has long been recognized as a potentially powerful tool for hydrological modelling. A single radar station is able to provide detailed precipitation information over entire watersheds. The operational use of radar in water resources applications, however, has been limited. Interpretation of raw radar data requires several rigorous analytical steps and a solid understanding of the technology. In general, hydrologists’ lack of meteorological background and the persistence of systematic errors within the data, has led to a common mistrust of radar-estimated precipitation values. As part of the Enhanced Nowcasting of Extreme Weather project, researchers at McGill University’s J.S. Marshall Radar Observatory in Montreal have been working to improve real-time quantitative precipitation estimates (QPEs). The aim is to create real-time radar precipitation products for the water resource community that are reliable and properly validated. The validation of QPEs is traditionally based on how well observed measurements agree with data from a precipitation gauge network. Comparisons between radar and precipitation gauge quantities, however, can be misleading. Data from a precipitation gauge network represents a series of single-point observations taken near ground surface. Radar, however, estimates the average rate of precipitation over a given area (i.e. a 1-km grid cell) based on the intensity of reflected microwaves at altitudes exceeding 1 km. Additionally, both measurement techniques are susceptible to a number of sources of error that further confound efforts to compare the two. One of the greatest challenges facing radar meteorologists is the variation in the vertical profile of reflectivity (VPR). A radar unit creates a volumetric scan of the atmosphere by emitting microwave beams at several elevation angles. As a beam travels away from the radar, its distance from ground surface increases. Different precipitation types are sampled at a number of heights (i.e. snow above the 0º C elevation and rain below it) that vary with range. The difficulty lies in estimating the intensity of precipitation at the Earth’s surface, based on measurements taken aloft. Scientists at McGill University have incorporated VPR correction techniques into algorithms used to automatically convert raw radar data into quantitative hydrological products. This thesis evaluates three real-time radar precipitation products from McGill University’s J.S. Marshall Radar Observatory in the context of hydrological modelling. The C0 radar product consists of radar precipitation estimates that are filtered for erroneous data, such as ground clutter and anomalous precipitation. The C2 and C3 radar products use different VPR correction techniques to improve upon the C0 product. The WATFLOOD hydrological model is used to assess the ability of each radar product to estimate precipitation over several watersheds within the McGill radar domain. It is proposed that using a watershed as sample area can reduce the error associated with sampling differences between radar and precipitation gauges and allow for the evaluation of a precipitation product over space and time. The WATFLOOD model is run continuously over a four-year period, using each radar product as precipitation input. Streamflow hydrographs are generated for 39 gauging stations within the radar domain, which includes parts of eastern Ontario, south-western Quebec and northern New York and Vermont, and compared to observed measurements. Streamflows are also modelled using distributed precipitation gauge data from 44 meteorological stations concentrated around the Montreal region. Analysis of select streamflow events reveals that despite the non-ideal placement of precipitation gauges throughout the study area, distributed precipitation gauge data are able to reproduce hydrological events with greater accuracy and consistency than any of the provided radar products. Precipitation estimates within the McGill radar domain are found to only be useful in areas within the Doppler range (120-km) where the radar beam is unobstructed by physiographic or man-made features. Among radar products, the C2 VPR-corrected product performed best during the greatest number of the flood events throughout the study area.
25

Optical and Mechanical Properties of Thin Film Metallic Glasses

Hu, Ting-ting 23 July 2012 (has links)
This study is separated into two parts. Firstly, the Ag thin film was deposited on substrates with different average roughness by sputtering to examine the effect of substrate roughness on optical reflection. The results exhibit 10 percent difference of reflectivity within several nanometer changing in average roughness, indicating the reflectivity is easily affected by surface roughness. Secondly, optical reflectivity and electrical resistivity of multi-component AgMgAl alloys, both crystalline and amorphous, were measured. The crystalline alloys exhibit high reflection in infrared region but a steeper drop in visible and ultraviolet regions. By contrast, amorphous alloys show a lower but relatively uniform reflectivity in the visible and infrared regions. In both cases, the reflectivity was observed to scale with the square root of electrical resistivity. The scaling law was explained based on classical reflection theory. The different scaling factors for crystalline and amorphous alloys could be rationalized by the difference in the mean free time of charge carriers. Moreover, the mechanical properties of crystalline and amorphous thin film alloys, including hardness and modulus, were measured by nanoindentation. The hardness of thin film metallic glasses (TFMGs) is obviously higher than crystalline metals, while the modulus of TFMGs is similar to crystalline metals.
26

Study on The Application of FLOW-3D for Wave Energy Dissipation by a Porous Structure

Chen, Chun-Ho 11 September 2012 (has links)
Wave is one of the most common dynamic factors in marine engineering. This is the major affecting factor in the design of structures and coastal engineering that wave affect the structure or the coast, so there are many topics about wave absorbing issues. In this paper, FLOW-3D modeling is implemented for wave interaction with porous structures, and comparing with experiment. This is very different between the results of models using the proposed method by the FLOW-3D User Manual to set drag coefficients of porous media and the results of experiments. Therefore, to discuss the setting drag coefficients of porous media is one of this research project. Configuration of this study, four different types of porous structures to explore the interaction with wave, the major categories: single, double and three-tier (two forms). FLOW-3D simulations of wave boundary in this article is to simulate the wave plate to manufacture wave, FLOW-3D simulations of wave with the previous studies are different with its built-in wave boundary. The results of simulation compare with experiment, and obtain water depth data both of them, and then programmatically wave analysis explore the differences between simulation and experiment. The simulation results show that stroke set by the analog wave board need to reduce 10 percent of the original settings, and the simulation results are similar to experiment results. The differences between simulation and experiment are smaller when porous media parameter ¡¥b¡¦ setting formula adjust to 0.03/D ( D is the particle diameter)and parameter ¡¥a¡¦ setting formula changeless. Reducing wave of the four porous structures relate to the wave period. The wave period is bigger and more difficult to wave absorption, and the reflectivity is proportional to wave period.
27

A study of the selective reflection properties of some liquid crystalline cellulose derivatives

Rodden, Gillian Isabella January 2001 (has links)
No description available.
28

Polymer Nanocomposite Analysis and Optimization for Renewable Energy and Materials

Henry, Nathan Walter 01 December 2011 (has links)
Polymer nanocomposites are an important research interest in the area of engineering and functional materials, including the search for more environmentally materials for renewable energy and materials. The ability to analyze and optimize morphology is crucial to realizing their potential, since the distribution of materials in the composite strongly influences its properties. This dissertation presents research into three different polymer nanocomposite systems with three different applications that underscore the need to understand and control the composite morphology to succeed. The first project details work on development of a copolymer compatibilizer to enhance the dispersion of the plant-derived biopolymer lignin in composite blends with polystyrene. The copolymer was designed with hydroxyl functionality that can form hydrogen bonds with lignin, and the effect of modulating the density of these groups was investigated, both on bulk dispersion and interfacial mixing. The second project presented concerns resolving the interfacial morphology of composite bulk heterojunction organic photovoltaic devices based on a polythiophene-based photoactive polymer and a modified carbon fullerene, which are archetypical of the highest performing cells yet produced. Neutron reflectivity was extensively employed to probe the interfacial width and degree of intermixing between the components to elucidate the morphological impact on device performance. The final project involves modifying nanoscale cellulose crystallites, dubbed nanowhiskers, by replacing a portion of the hydroxyl groups with acetate groups to improve their dispersion in polymethyl methacrylate. Neutron reflectivity was again employed to probe the interface between the two materials to observe and quantify intermixing.
29

As consequências previstas e não antecipadas da ação na análise funcional dos grupos de Robert K. Merton / The known but unanticipated consequences of action in the group functional analysis from Robert K. Merton

Batista, Marcos Antonio Rehder 16 August 2018 (has links)
Orientador: Gilda Figueiredo Portugal Gouvêa / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Filosofia e Ciências Humanas / Made available in DSpace on 2018-08-16T02:23:23Z (GMT). No. of bitstreams: 1 Batista_MarcosAntonioRehder_M.pdf: 1684627 bytes, checksum: 2fe52795396c836bfa1c547d56e25bef (MD5) Previous issue date: 2010 / Resumo: O presente trabalho é estudo sobre a revisão feita por Robert K. Merton da analise funcional clássica, tomando por base a leitura e crítica sobre o sociólogo norte-americano feita por Anthony Giddens. Tentou-se responder os principais questionamentos apresentados pelo sociólogo britânico e demonstrar-se que a distinção entre funções manifestas e latentes pode superar o problema do papel do ator na mudança social. Um outro objetivo foi extrair da teoria dos grupos de referência a forma com que um líder rearranja os conflitos entre grupos para conseguir poder / Abstract: This present work is a study about the Robert K Merton?s revision of the classical functional analysis, using the lecture and critic writhed by Anthony Giddens about this American sociologist. It?s try to answer mains questions asked from the british sociologist and demonstrate in the distinction manifest and lantent function can overcame the trouble of the actor role in the social change. One other subject is extract from theory of reference group the way that a leader organizes the conflict between groups to give power / Mestrado / Teoria Sociológica / Mestre em Sociologia
30

Determination of Sensors Characteristics of Curb and Development of Surrogate Curb for the Evaluation of Vehicle Active Safety Systems

Pandey, Seeta Ram 05 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Over the years, car driving experience has evolved drastically. Many new and useful technologies have emerged, which have enhanced safety and reliability measures. The Automotive world is now trying to build capabilities for driverless or vehicle assisted driving. Building capabilities for driverless cars practically means first developing training methods, then training the machine, evaluating the test results, and then based on testing results; develop a confidence interval for trusting the machine. One of the critical models is the model adopting the Road Departure Assisting Techniques (RDAT). These techniques are primarily the standards for alleviating the risk of roadside fatalities. The different models developed or proposed for RDAT falls under “The Road Departure Mitigation System” (RDMS). But, almost every RDMS to date has over-reliance on the presence and the quality of the lane markings. In the absence of lane markings or of proper lane markings, these RDMS are unreliable. Therefore, RDMS requires new references such as roadside objects and road edges for detecting road departures. This new system should propose and establish a standard for RDMS testing with roadside objects. As the foremost task, this new system requires the creation of a testing environment consisting of soft, robust, and reusable surrogates. Critically, these surrogates must have comparable sensors characteristics to those of real roadside objects from various commonly used object detection sensors on the vehicles such as camera, radar, and LIDAR. One of such everyday roadside objects is the curbs. For developing a surrogate for the curb, the first step is to recognize what the roadside objects should look like concerning different sensors, and the next step is to design and develop a surrogate curb that successfully follows the properties of the real roadside objects. This thesis first demonstrates and proposes the methods for extracting the color, Radar reflectivity, and the LiDAR reflectance properties of real roadside curbs. That is, the study deals with what all color combinations and patterns represent the US roadside curbs, what should be the range of Radar reflectivity values, and LiDAR reflectance bounds that a surrogate curb should satisfy. The later part of the thesis illustrates methods and steps on how to mimic the extracted properties, design a surrogate curb as per federal standards, and then develop a surrogate curb. Finally, the surrogate curbs were subjected to crash tests for testing their robustness.

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