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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

Experimental and numerical investigation of high viscosity oil-based multiphase flows

Alagbe, Solomon Oluyemi 05 1900 (has links)
Multiphase flows are of great interest to a large variety of industries because flows of two or more immiscible liquids are encountered in a diverse range of processes and equipment. However, the advent of high viscosity oil requires more investigations to enhance good design of transportation system and forestall its inherent production difficulties. Experimental and numerical studies were conducted on water-sand, oil-water and oilwater- sand respectively in 1-in ID 5m long horizontal pipe. The densities of CYL680 and CYL1000 oils employed are 917 and 916.2kg/m3 while their viscosities are 1.830 and 3.149Pa.s @ 25oC respectively. The solid-phase concentration ranged from 2.15e-04 to 10%v/v with mean diameter of 150micron and material density of 2650kg/m3. Experimentally, the observed flow patterns are Water Assist Annular (WA-ANN), Dispersed Oil in Water (DOW/OF), Oil Plug in Water (OPW/OF) with oil film on the wall and Water Plug in Oil (WPO). These configurations were obtained through visualisation, trend and the probability density function (PDF) of pressure signals along with the statistical moments. Injection of water to assist high viscosity oil transport reduced the pressure gradient by an order of magnitude. No significant differences were found between the gradients of oil-water and oil-water-sand, however, increase in sand concentration led to increase in the pressure losses in oil-water-sand flow. Numerically, Water Assist Annular (WA-ANN), Dispersed Oil in Water (DOW/OF), Oil Plug in Water (OPW/OF) with oil film on the wall, and Water Plug in Oil (WPO) flow pattern were successfully obtained by imposing a concentric inlet condition at the inlet of the horizontal pipe coupled with a newly developed turbulent kinetic energy budget equation coded as user defined function which was hooked up to the turbulence models. These modifications aided satisfactory predictions.
22

An Evaluation of the Implementation of a CALL Program in a Pilot Curriculum at the Provo LDS Missionary Training Center

Betteridge, Amberly Patch 05 August 2011 (has links)
The current study examines the implementation of one computer-assisted language learning program (CALL) called Technology Assisted Language Learning (TALL) in a pilot language curriculum at the LDS Missionary Training Center. Because CALL implementation is determined in large part by how successfully users are able to use the computer program to learn language, a primary purpose of this study was to investigate which implementation issues affected the language learning success of the missionaries that used TALL in the pilot curriculum. A survey was, therefore, designed and administered to 86 missionaries from French, Spanish, German, and Mandarin language areas in order to determine which CALL user characteristics were predictive of TALL user success. Through a regression analysis , this study found that the most highly predictive factors on TALL user success were (a) a high indication of pro-activity on the part of the learners in figuring out how to use TALL to their advantage, (b) a high indication of goal-orientation in approaching TALL use with a specific purpose in mind, and (c) a high indication of interaction with the TALL program through frequent use of the electronic glossary feature, the "listen to your voice" feature, and the strategy of repeating out loud the words and phrases encountered while working on TALL. The missionary survey was also analyzed descriptively, and results from this analysis revealed that missionaries in the pilot curriculum felt that more training on how to use TALL effectively would have helped them to be more successful. Focus groups with the missionaries were also conducted in order to better understand their experiences with the TALL program. The analysis of these focus groups revealed that although many missionaries reported liking TALL, there were many who did not sufficiently understand how to successfully use it within the pilot curriculum; a lack of training seemed to be a big contributor to this lack of user success. Additionally, focus groups found that missionaries believed the TALL listening activities to be the most helpful TALL activities. A teacher survey was also designed and administered to the 19 teachers who taught missionaries in the pilot curriculum. Results of the teacher survey revealed a desire for more formal training on how to train missionaries to use the TALL program effectively. In conclusion and based on evidence in the literature and from this study, suggestions are provided for more effective teacher and learner training on TALL.
23

L'approche bayésienne pour l'évaluation médico-économique : Méta-analyse bayésienne en réseaux et la calibration bayésienne / Bayesian approach in health economic evaluation : Mixed treatment comparison and Bayesian calibration

Neine, Mohamed El Moctar 17 December 2015 (has links)
Les objectifs de ma thèse étaient d'analyser les avantages et les inconvénients de l'approche bayésienne et développer leur utilisation dans le contexte de l'évaluation médico-économique. Deux projets ont été développés en utilisant l'approche bayésienne. Le premier projet était une revue systématique de la littérature et méta-analyse en réseaux pour estimer l'efficacité et la tolérance mirabegron 50 mg par rapport aux autres traitements anti-muscarinique dans la gestion de l’hyperactivité vésicale. Une revue de littératures a permis d’identifier les données puis des modèles à effet fixes et effet aléatoires ont été utilisés. Le deuxième projet est le développement de la méthode de calibration bayésienne pour estimer les probabilités de transition d’un modèle de Markov dans la maladie de Parkinson. Une étude de simulation a été effectuée pour comparer les résultats de l'approche bayésienne et l'approche classique. Toutes les analyses ont été effectuées en utilisant les logiciels libres WinBUGS et R. Résultats: La méta-analyse bayésienne en réseaux est un outil très utile pour gérer la comparaison directe et indirecte de traitements. la calibration Bayésiennes, les résultats de l’approche bayésiens sont distribués de façon similaire par rapport aux résultats de l'étude de référence.Conclusion: En comparaison avec l’approche classique, l’approche bayésienne à une meilleure base mathématique et philosophique, offre une plus grande flexibilité, et fournit des résultats sous une forme plus naturelle et intuitive. L'utilisation de l'approche bayésienne devrait se poursuivre et se développer dans le domaine de l'économie de la santé. / The objectives of this thesis were to review and develop the use of Bayesian approach in the context of heath economic evaluation. Methods: Two projects of health economics were developed to assess the benefit of Bayesian approach in health economics. The first project was a systematic literature review and mixed treatment comparison to estimate the relative efficacy and safety of mirabegron compared to antimuscarinics treatments in the management of over active bladder (OAB). The second project was the development of Bayesian calibration method to estimate the transition probabilities from cost-effectiveness model. A simulation study was performed to compare the results of Bayesian approach and classical approach. All the analyses were performed using free software WinBUGS and R.Results: The Bayesian approach is widely used in health economic evaluation and it is accepted tool to analyse the data from most of health technology agencies (e.g. HAS, NICE). The Bayesian mixed treatment comparison found to be a very useful framework to handle the comparison of treatments using the information from direct and indirect treatment comparison. The Bayesian calibration method provided results similarly distributed compared to the results of reference study (i.e. simulation study). Conclusion:Bayesian approach has better mathematical and philosophical foundation, offers greater flexibility, and provides results in a more natural and intuitive form. The use of Bayesian approach is expected to continue and grow in the field of health economics and outcomes research, because failing of frequentist to reply to some difficult question and due to the development of high-power computers.
24

Experimental and numerical investigation of high viscosity oil-based multiphase flows

Alagbe, Solomon Oluyemi January 2013 (has links)
Multiphase flows are of great interest to a large variety of industries because flows of two or more immiscible liquids are encountered in a diverse range of processes and equipment. However, the advent of high viscosity oil requires more investigations to enhance good design of transportation system and forestall its inherent production difficulties. Experimental and numerical studies were conducted on water-sand, oil-water and oilwater- sand respectively in 1-in ID 5m long horizontal pipe. The densities of CYL680 and CYL1000 oils employed are 917 and 916.2kg/m3 while their viscosities are 1.830 and 3.149Pa.s @ 25oC respectively. The solid-phase concentration ranged from 2.15e-04 to 10%v/v with mean diameter of 150micron and material density of 2650kg/m3. Experimentally, the observed flow patterns are Water Assist Annular (WA-ANN), Dispersed Oil in Water (DOW/OF), Oil Plug in Water (OPW/OF) with oil film on the wall and Water Plug in Oil (WPO). These configurations were obtained through visualisation, trend and the probability density function (PDF) of pressure signals along with the statistical moments. Injection of water to assist high viscosity oil transport reduced the pressure gradient by an order of magnitude. No significant differences were found between the gradients of oil-water and oil-water-sand, however, increase in sand concentration led to increase in the pressure losses in oil-water-sand flow. Numerically, Water Assist Annular (WA-ANN), Dispersed Oil in Water (DOW/OF), Oil Plug in Water (OPW/OF) with oil film on the wall, and Water Plug in Oil (WPO) flow pattern were successfully obtained by imposing a concentric inlet condition at the inlet of the horizontal pipe coupled with a newly developed turbulent kinetic energy budget equation coded as user defined function which was hooked up to the turbulence models. These modifications aided satisfactory predictions.
25

Impact of Extended DRX Cycles on Battery Lifetimes and UE Reachability

Cholaraju Narasaraju, Vignesh January 2016 (has links)
Several UE energy consumption optimization techniques have been proposed for Machine Type Communication (MTC) devices. Extended Discontinuous Reception (eDRX) in idle mode is one such technique wherein an UE in idle mode wakes up only during its Paging Occasion (PO) to monitor paging messages from eNodeB (eNB). The PO is located within a Paging frame (PF). The PF is a function of System Frame Number (SFN) cycle of eNB. The paging messages may be sent asynchronously from multiple eNBs to a UE. Due to asynchronous operation of eNBs, SFN takes on different values at a given point in time and therefore a paging message is transmitted at different points in time from different eNBs. Due to this SFN misalignment between eNBs, an idle mode UE might receive and respond to the same paging message from different eNBs and/or miss a PO and thus the paging message. Due to this spread in time of SFN and PO, the actual handling of paging message by the UE becomes inefficient leading to increased UE energy consumption and decreased reachability. These issues, resulting from paging handling, will get amplified further if DRX period is extended longer (eDRX). In this study, we investigate the impact of eDRX cycles and mobility related parameters such as UE speed, cell size and size of SFN misalignment between eNBs on UE energy consumption, use of network resources and UE reachability. Receiving and responding to the same paging message results in increased energy consumption for UE and increased signaling between UE and the network. Missing a PO results in delayed paging reception and hence decreases UE reachability. As the DRX cycle lengths are increased from existing maximum of 2.56 seconds to 10.24 seconds and beyond, we see a reduction in UE energy consumption by more than 90%, but the network signaling and the delay to reach the UE increases linearly as a function of the DRX cycle length. We observe that the number of duplicate paging message receptions/missed POs is minuscule for DRX cycle lengths below 10.24 sec. At DRX cycle length of 10.24 seconds, UEs travelling across 500 m cell radius at speeds of 3, 50, 100 km/h the percentage of duplicate paging receptions are 0.07, 0.11, and 0.15 respectively. This duplicate paging message reception increases the UE energy consumption by 2.31, 6.15 and 12 percent of the total energy units respectively. Similarly, UE misses nearly 0.34, 0.39, and 0.405 percent of the total POs respectively. Depending on the number of consecutive PO misses, the UE reachability decreases. But by reducing the size of SFN misalignment between eNBs, we see that it’s possible to increase the reachability for UEs in eDRX. Further we have proposed solutions based on our analytical study to avoid duplicate paging message reception by UE, increase UE reachability and also reduce UE energy consumption using a windowing technique. We conclude that when a UE is configured with eDRX cycles, the tradeoff between battery lifetimes and UE reachability is based on mobility characteristics and service requirements.
26

Konvertor synchronizačního kódu MTC a LTC / MTC and LTC Sync Code Converter

Miškařík, Vít January 2018 (has links)
Converter of sync codes MTC to LTC is very important device to synchronize all devices which are being used for editing and other work with audio and video. Most of digital equipment can sync to MTC but LTC timecode is recorded od audio or videotape. Therefore this converter is needed to sync all connected devices to recorded timecode. This thesis is about designing and constructing the converter between these timecodes.
27

Investigating the Correlation Between Freeway Service Levels and Freeway Service Patrol Assists

Chin, Nora 01 September 2015 (has links) (PDF)
The Bay Area Metropolitan Transportation Commission’s (MTC) Freeway Service Patrol’s highway motorist response service is reporting a reduction in their service levels. We analyze the relationship between the reduction in the Bay Area Freeway Service Patrol’s (FSP) motorist assists and changes in vehicle miles traveled (VMT), California Highway Patrol (CHP) reported incidents, and cover research on the impact of new and old vehicle fleet turnover. VMT and CHP incidents have differential effects on FSP assists. Although incidents occurring on freeways with high traffic flows tend to cause more congestion, the trend in local VMT along Bay Area freeway corridors does not share a strong correlation with FSP assists. Through a chi-square test, bivariate correlation and cross tabulation, we can see a relationship and pattern between FSP assists, incidents and VMT. Further analysis into the dispersion of assists, incidents and VMT show that the distribution of the FSP assists over CHP reported incidents is not perfectly equal. By analyzing VMT, CHP reported incidents and research around new vehicle fleet turnover affecting FSP assisted-incidents, Metropolitan Transportation Commission staff can systematically improve the FSP operational model; strategize ways to improve service on needier freeway corridors, while reducing unnecessary service in other regions.
28

Výzkum spolehlivé komunikace pro IoT aplikace v bezdrátových sítích využívajících technologie Multi-RAT LPWAN / Research on Reliable Low-Power Wide-Area Communications Utilizing Multi-RAT LPWAN Technologies for IoT Applications

Štůsek, Martin January 2021 (has links)
Předkládaná disertační práce je zaměřena na „Výzkum spolehlivé komunikace pro IoT aplikace v bezdrátových sítích využívajících technologie Multi-RAT LPWAN“. Navzdory značnému pokroku v oblasti vývoje LPWA technologií umožňující masivní komunikace mezi zařízeními (mMTC), nemusí tyto technologie výkonnostně dostačovat pro nově vznikající aplikace internetu věcí. Hlavním cílem této disertační práce je proto nalezení a vyhodnocení limitů současných LPWA technologií. Na základě těchto dat jsou nevrženy nové mechanismy umožňující snazší plánování a vyhodnocování síťového pokrytí. Navržené nástroje jsou vyladěny a validovány s využitím dat získaných z rozsáhlých měřících kampaních provedených v zákaznických LPWA sítích. Tato disertační práce dále obsahuje návrh LPWA zařízení vybavených více komunikačními rozhraními (multi-RAT) které mohou umožnit překonání výkonnostních limitů jednotlivých LPWA technologií. Současná implementace se zaměřuje zejména na snížení spotřeby zařízení s více rádiovými rozhraními, což je jejich největší nevýhodou. K tomuto účelu je využito algoritmů strojového učení, které jsou schopné dynamicky vybírat nejvhodnější rozhraní k přenosu.
29

Medical tax benefits to South African taxpayers : an overview

Moosa, R. 09 1900 (has links)
This study presents an overview of the medical expenditure allowed to taxpayers in the South African Income Tax Act, 58 of 1962 (hereafter the “Income Tax Act”). The study traces the changes made to the allowed expenditure over time. Changes made to the Income Tax Act, illustrating the effect of qualifying medical expenses on the income of persons with disabilities in terms of the Income Tax Act, are described. Certain provisions of the Income Tax Act, as well as other legislation dealing with persons with disabilities, were analysed. Furthermore, the research shows the effect of moderate to severe limitations on a person’s ability to claim qualifying medical expenses. In particular, the change over from the medical tax deduction system (section 18 of the Income Tax Act) to the medical tax rebate system (sections 6A and 6B of the Income Tax Act) to redress the inequality between high income and low income earners, was analysed. Case studies were used to illustrate that the medical tax deduction system (section 18 of the Income Tax Act) favoured high income earners over low income earners. Finally, the change over from the medical tax deductions (section 18 of the Income Tax Act) system to the current system of medical tax rebates (sections 6A and 6B of the Income Tax Act) was analysed. Except for a very small group of taxpayers, the medical tax rebate system (sections 6A and 6B of the Income Tax Act) was found to be financially more favourable to all taxpayers. / Taxation / M. Compt. (Taxation)

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