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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.
701

A comparative study of the simulation of daily streamflow sequences

Thambirajah, Percy Anandarajah January 1973 (has links)
Using three years of daily streamflow and meteorological data from the Similkameen watershed at Princeton, B.C., the model parameters of the existing deterministic UBC Budget Model are evaluated. With these model parameters and the available meteorological data, the synthetic streamflow sequences are generated for the other seven years for the Similkameen watershed. These are subsequently compared with the actual flows. A separate statistical stochastic model is developed by using the spectral analysis, and the three years of the same daily flows are decomposed into 30 sub-harmonics or Fourier coefficients. By interpolating the Fourier coefficients and by estimating the anticipated mean annual flows from the snowpack data at Blackwall Peak, the synthetic traces of the daily streamflow sequences are simulated for the other seven years. A first order Markovian model is used to explain the random component. The comparative study is then carried out between the actual daily streamflow sequences and those generated by the deterministic UBC Budget Model and the stochastic spectral model. In comparison with the stochastic spectral model, good fits are obtained with the fixed model parameters of the UBC Budget Model for the sequence of peaks for the simulated hydro-graphs of the intervening years. Since the winter melt factor in the UBC Budget Model was assumed to be a constant for this analysis, some errors occur between the actual and the generated cumulative volumes. With the deterministic periodic component of the spectral model, the reconciliation between the cumulative volumes is fairly well maintained. Since the role of operational hydrology is not concerned with the prediction of actual flows, the stochastic spectral model should be judged on its ability in presenting the designer with a series of synthetic traces that are likely to occur during the lifetime of a particular project. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
702

Development of a research watershed system and a streamflow prediction model

Kennedy, Gary Franklin January 1969 (has links)
Two independent hydrologic research projects, the development of (1) a research watershed system and (2) a streamflow prediction model, were carried out. The first project was primarily a field instrumentation task involving both design and implementation of a system of research watersheds. Two small (50 acre) research watersheds which may become either representative or experimental in nature were initiated within the University of British Columbia Research Forest. A larger research watershed system was described which could include the Alouette River Watershed. This system of watersheds when subjected to more rigorous experimental procedures should yield valuable, management and conservation design criteria for Pacific Coast forested regions. The second project was primarily analytic in nature, employing the use of multiple regression and a digital computer. A computer program was developed which models the snowmelt streamflow of large watersheds in a manner which makes short term prediction of the streamflow possible. The prediction variables were temperature recorded at a single centrally located station, time and streamflow recorded at the outlet from the watershed. The model predicted flood flow one to five days in advance of measured streamflow for the Fraser River Watershed (78,000 square miles in area) during the spring runoff period of 1955 and 1964. This model required calibration at the beginning of each spring runoff period. / Science, Faculty of / Resources, Environment and Sustainability (IRES), Institute for / Graduate
703

Coincidence methods for determining scintillation counter efficiency

Hepburn, John Duncan January 1967 (has links)
The efficiency of a 4" x 5" Nal(Tl) scintillation counter for detecting gamma-rays has been measured by a number of experimental techniques, and the results compared with the efficiencies predicted from total absorption cross sections. The experimental techniques involve coincidence measurements of the cascade gamma-rays from a Co-60 source (1.173 MeV and 1.333 MeV), and from the reaction B¹¹(pγγ)C¹² (4.43 MeV and 11.68 MeV). The Co-60 measurements also lead to knowledge of the absolute strength of the sources. For both cascades it was necessary to know the angular correlations between the radiations; for the reaction B¹¹ (pγγ)C¹² a separate investigation of this correlation was made using a 180 KeV accelerator. Computer programs were written to analyze the experimental data, and to calculate the theoretical efficiency estimates, taking into account the collimator and shield geometry. The results of this work define the efficiency of the scintillation counters to better than 5% for a number of gamma-ray energies and a specific geometry. On the other hand, the efficiencies based on the total number of counts in the observed spectra were 20 percent to 40 percent higher than the theoretical efficiencies. The departures from theory depend on the gamma-ray energy and the geometry of the shielding and collimators in such a way that it is not possible to provide a simple basis for relating theoretical efficiencies to the experimental data. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
704

A parametric study of rigid body-viscous flow interaction

Moorty, Shashi January 1987 (has links)
This thesis presents the numerical solution for two-dimensional incompressible viscous flow over a rigid bluff body which is elastically supported or alternately undergoing a specified harmonic oscillations. Solutions for the related associate flow in which the body is at rest in a two-dimensional incompressible time-dependent viscous flow have also been -obtained. This work is an extension of the work by Pattani [19] to include the effect of a steady far field flow on an oscillating body. The numerical model utilizes the finite element method based on a velocity-pressure primitive variable representation of the complete Navier-Stokes equations. Curved isoparametric elements with quadratic interpolation for velocities and bilinear interpolation for pressure are used. Nonlinear boundary conditions on the moving body are represented to the first order in the body amplitude parameter. The method of averaging is used to obtain the resulting periodic motion of the fluid. Three non-dimensional parameters are used to completely characterise the flow problem: the frequency Reynolds number Rω , the Reynolds number of steady flow Rℯ₁ and the Reynolds number for time-dependent flow Rℯ₂. Numerical results are obtained for a circular body, a square body and an equilateral triangular body. A parametric study is conducted for different values of the Reynolds numbers in the viscous flow regime. In all cases, results are obtained for streamlines, streaklines, added mass, added damping, added force and the drag coefficients. The limiting cases of steady flow over a fixed body and an oscillating body in a stationary fluid are checked with known results. Results for the associated flow are also obtained. The transformations derived, between the two associated flows are checked. Good agreement is obtained between the present results and other known results. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate
705

ESR and microwave conductivity studies in DEM(TCNQ) above room temperature

Cabañas, Francisco Xavier January 1981 (has links)
Two phase transitions have been found in DEM(TCNQ)₂ at 400(3) K and at 442(6) K to 453(6) K using ESR and measurements of the microwave conductivity. These temperatures are less than the values of 415 K and 483 K previously obtained from temperature dependent Guinier measurements. Below 400(3) K two ESR lines, I and II are observed corresponding to the two stacks, B and A, in DEM(TCNQ)₂. Above 400(3) K and below 453(6) K only one line remains with the same g value as line I. The angular dependence of the g value was fitted to g[sub=‖]² = g[sub=⊥] ²cos2θ + g²sinθ and values of g[sub=⊥] = 2.003551(14) and g[sub=‖] = 2.00273015) were obtained. Between 298 K and 442(6) K the conductivity was that of a semiconductor with an exitation energy E[sub=0] = 0.385(52) e.v. The -4k[sub=⌐] phase transition is postulated at 447(9) K. The phase transition at 400(3) K is due to a transfer of spin density from stack A to stack B, and has no effect on the total spin susceptibility or on the conductivity to within the experimental error. / Science, Faculty of / Physics and Astronomy, Department of / Graduate
706

Within Study Dependence in Meta-Analysis: Comparison of GLS Method and Multilevel Approaches

Unknown Date (has links)
Multivariate meta-analysis methods typically assume the dependence of effect sizes. One type of experimental-design study that generates dependent effect sizes is the multiple-endpoint study. While the generalized least squares (GLS) approach requires the sample covariance between outcomes within studies to deal with the dependence of the effect sizes, the univariate three-level approach does not require the sample covariance to analyze such multivariate effect-size data. Considering that it is rare that primary studies report the sample covariance, if the two approaches produce the same estimates and corresponding standard errors, the univariate three-level model approach could be an alternative to the GLS approach. The main purpose of this dissertation was to compare these two approaches under the random-effects model for synthesizing standardized mean differences in multiple-endpoints experimental designs using a simulation study. Two data sets were generated under the random-effects model: one set with two outcomes and the other set with five outcomes. The simulation study in this dissertation found that the univariate three-level model yielded the appropriate parameter estimates and their standard errors corresponding to those in the multivariate meta-analysis using the GLS approach. / A Dissertation submitted to the Department of Educational Psychology and Learning Systems in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2014. / November 6, 2014. / effect sizes, gls, meta-analysis, multilevel, multivariate / Includes bibliographical references. / Betsy Jane Becker, Professor Directing Dissertation; Fred Huffer, University Representative; Insu Paek, Committee Member; Yanyun Yang, Committee Member.
707

Spirometric and gas transfer measurements among normal adult South African men : an investigation into anthropoemtric, socio-economic, racial and environmental factors influencing lung function

Goldin, Jonathan Gerald 06 April 2020 (has links)
An investigation into anthropocentric, socio-economic, racial and environmental factors influencing lung function. In modern clinical practice the data derived from pulmonary function tests are an integral part of the evaluation of pulmonary disease states. Such data may shed light on the nature of the disease state, the extent (severity) of the disease and the degree of functional impairment that is present. It is generally recognized that there is a lack of consistent data regarding "normal" values in pulmonary function. Despite great progress in standardizing instrumentation, methodology and calculation of the lung function test, the interpretation of the test is complicated by the lack of standardized prediction values. The identification of race as a confounding variable is particularly important in an evaluation of appropriateness of currently used pulmonary function reference values. It has been pointed out that reference values for blacks, in particular, have deficiencies and that this issue demands urgent investigation. The study of differences in lung function in different race groups is complex. Race, itself, is a controversial concept and its close relationship to social stratification needs to be explored before differences may be attributed to race itself.
708

Using Partially Observed Markov Decision Processes (POMDPs) to Implement a Response to Intervention (RTI) Framework for Early Reading

Unknown Date (has links)
The dissertation explored the efficacy of using a POMDP to select and apply appropriate instruction. POMDPs are a tool for planning: selecting a sequence of actions that will lead to an optimal outcome. RTI is an approach to instruction, where teachers craft individual plans for students based on the results of screening test. The goal is to determine whether the plans crafted by a POMDP model in a RTI setting offer advantages over the current practice that uses simple cut score methods. Two simulated data sets were used to compare the two approaches; the model had a single latent reading construct and two observed reading measures: Phoneme Segmentation Fluency (PSF) for phonological awareness and Nonsense Word Fluency (NWF) for phonics. The simulation studies evaluated the POMDPs forecasts of the students' end-of-year reading performance, and the studies compared how the students were placed into instructional groups using the two approaches. The POMDP-RTI model forecasted the students PSF and NWF scores for the last time period based on their scores in the previous time period as well as a forecast standard deviation. In the study, 91% of PSF scores and 94% of NWF scores fell within two standard deviations. The assignment to tiers was very different (after the initial time block) with just over half the students assigned differently under the two models at the last time point. The growth was better under the POMDP-RTI approach with a difference in mean reading ability of .49 on a standardized scale. The gain is because the POMDP model can take into account past observations and instructional history in its forecasts. / A Dissertation submitted to the Department of Educational Psychology and Learning Systems in partial fulfillment of the Doctor of Philosophy. / Spring Semester 2016. / March 31, 2016. / MCMC, POMDP, POMDP-RTI, RTI / Includes bibliographical references. / Russell G. Almond, Professor Directing Dissertation; Young-Suk Kim, University Representative; Betsy J. Becker, Committee Member; Insu Paek, Committee Member.
709

Development, Evaluation and Refinement of a Body Mass Index Formula for Large Breed Canine Patients

Lodato, Dena Lynn 11 May 2013 (has links)
The current method of quantifying obesity in the veterinary patient is the subjective body condition score; however, scant research has focused on the development of an objective measurement. The present two part study evaluates the ability to create and refine an objective body mass index (BMI) formula for the large breed canine patient. In the first part of this study, seven morphometric measurements were obtained from seventy large breed dogs allowing the creation of five BMI formulas. In the second part of this study, computed tomography images were obtained from twenty-two dogs and the total percent body fat (TBF) was calculated. Results from the five formulas were compared to the calculated TBF to evaluate their accuracy. A final BMI formula was developed that has a very strong correlation with the TBF, and provides an objective measurement of obesity in the large breed canine patient.
710

Une combinaison des methodes electromagnetiques a cadres horizontaux "Slingram" et Turam.

Lavoie, Clermont January 1972 (has links)
No description available.

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