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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.
171

Projeto, construção e caracterização de câmaras de ionização especiais para monitoração de feixes de radiação X / Design, construction and characterization of special ionization chambers for X radiation beams monitoring

Maíra Tiemi Yoshizumi 25 October 2010 (has links)
Os equipamentos de radiação X, por estarem ligados à rede elétrica, podem apresentar flutuações na intensidade de seus feixes de radiação. Essas variações na intensidade, podem, por sua vez, modificar a taxa de kerma no ar produzida por este feixe de radiação. Em um laboratório de calibração de instrumentos, onde são realizadas calibrações de diversos equipamentos detectores de radiação, utilizados principalmente em clínicas ou hospitais, essa possível variação na intensidade do feixe de radiação pode causar um erro na determinação da dose absorvida. As câmaras de ionização monitoras são utilizadas para verificar a constância da intensidade de feixes de radiação, e fornecer uma correção para possíveis oscilações. Neste trabalho foram projetadas, construídas e caracterizadas câmaras de ionização monitoras para feixes de radiação X. As câmaras de ionização desenvolvidas possuem formato inovador, anelar, com eletrodos de alumínio ou de grafite. Essas câmaras de ionização anelares apresentam a vantagem de não interferirem no feixe direto de radiação. Foi ainda construída uma câmara de ionização com volume duplo e eletrodos de grafite, similar à câmara de ionização monitora comercial utilizada no Laboratório de Calibração de Instrumentos do Instituto de Pesquisas Energéticas e Nucleares. Essas câmaras de ionização foram testadas em diversos feixes de radiação padronizados e seus desempenhos foram comparados aos de câmaras de ionização comerciais. Os resultados obtidos mostram que duas dentre as quatro câmaras de ionização desenvolvidas apresentaram desempenho comparável ao das câmaras de ionização comerciais testadas. Além de apresentarem bons resultados, as câmaras de ionização desenvolvidas foram feitas artesanalmente e utilizando materiais de baixo custo, que são facilmente encontrados no mercado. / X radiation equipment may show fluctuations in the radiation beam intensity, as they are connected to the power net. These intensity variations can, in turn, modify the air kerma rate produced by this radiation beam. In a calibration laboratory, where radiation detectors (from clinics and hospital services) are calibrated, variations in the radiation beam intensity may cause an error in the absorbed dose determination. The monitor ionization chambers are used to verify the radiation beam intensity constancy, and to provide a correction for possible fluctuations. In this work, monitor ionization chambers for X radiation beams were designed, assembled and characterized. The developed ionization chambers have an innovative design, ring-shaped, with aluminium or graphite electrodes. These ring-shaped ionization chambers have the advantage of not interfering in the direct radiation beams. A double-volume ionization chamber with graphite electrodes was also developed. This ionization chamber is similar to the commercial monitor ionization chamber used in the Calibration Laboratory of the Instituto de Pesquisas Energéticas e Nucleares. All developed ionization chambers were tested in several standardized radiation beams and their performances were compared with those of commercial ionization chambers. The results show that two of the four ionization chambers developed showed performance comparable to that of the commercial ionization chambers tested. Besides presenting good results, the ionization chambers were designed and manufactured using low cost materials, which are easily found on the Brazilian market.
172

Empowering Nurses through Knowledge and Technology to Decrease Fall Rates

Nwaise, Ngozi Doreen 01 January 2017 (has links)
Falls are nurse-sensitive outcome which reflect the quality of nursing care. Nurses, therefore, have a major role to play in efforts to decrease fall rates. The objective of this project is to increase nurses' knowledge on the proper use of the CVVM as an attempt to effectively decrease fall rates. Pretest, post test, and course evaluation data were collected from 30 nurses. A descriptive analysis of the data was performed. Overall, the pretest evaluation showed that nurses had an average score of 43% in the combined assessment of their knowledge on fall prevention strategies, their use of the CVVM, and their knowledge about the hospital's policy on patient monitoring. The nurses' post test average score in the combined assessment of these measures increased to 89% after the educational training which included presentations, hands-on-training, and provision of reference materials and cheat cards on fall prevention strategies and the use of the CVVM surveillance system. Inadequate training, lack of knowledge on the utilization of CVVM surveillance, inadequate use of system resources, and noncompliance with hospital policies were the primary drivers of fall rates in this hospital. Main recommendations include training and periodic retraining of staff on fall prevention strategies; leadership involvement to ensure nurses' compliance with the use of CVVM technology and hospital policy on patient monitoring; provision of CVVM reference materials; and nursing responsibilities in patient monitoring. Social change implications of this project include that nurses are better equipped through training to prevent falls, therefore, lowering patient morbidity and mortality rates.
173

Lebanese Elementary Teachers' Perceptions about Metacognitive Skills for Students with Learning Disabilities

Bassous, Tassoula Semaan 01 January 2019 (has links)
Teachers in Lebanese schools are still using outdated traditional strategies for instructing students with learning disabilities (LD). The purpose of this qualitative exploratory case study was to understand Lebanese elementary teachers' perceived barriers to providing effective metacognition skills instruction and increase the understanding of how teachers are supporting students with LD to use metacognitive strategies to enhance their own learning. The conceptual framework used to ground the study was Flavell's metacognitive theory. The purposeful sample included 12 elementary special and regular education teachers selected from 6 different Lebanese schools in 5 areas in Lebanon. Each teacher participated in a semistructed interview and was observed while teaching in the classroom. Coding and thematic inductive approaches based on elements of the conceptual framework were used to analyze the data. Peer debriefing, member checking, and triangulation by region were used to ensure credibility and trustworthiness. The findings revealed that teachers were knowledgeable about how to teach metacognitive skills, but they were not explicitly instructing those skills to students with LD. Among the reported barriers to teaching these skills included lack of time, perceived nature of the LD students' disability, and cultural expectations. The findings were used to provide recommendations for Lebanese teachers to implement in day-to-day instruction for students with LD and for school leaders to build teachers' capacity to engage LD students in constructing their own learning. This study may affect positive social change by promoting instruction of metacognitive strategies for students with LD to help them build lifelong 21st century skills.
174

Investigation of exposure assessment methods and filtration of carbon nanotubes

Holder, Craig Alan 01 May 2017 (has links)
The research presented in this doctoral dissertation aimed to improve knowledge on methods to evaluate exposures to carbon-containing nanomaterials and to develop optimized respiratory filters properties to protect workers from these exposures while minimizing discomfort due to breathing resistance. In the initial study, a novel laboratory-based system generated aerosols of four carbon-containing powders (carbon black, a small-diameter (< 8 nm) multi-walled carbon nanotube (MWCNT), a large-diameter (50-80 nm) MWCNT, and a nickel-coated MWCNT) to evaluate the effectiveness of NIOSH Method 5040 for measuring masses as low as 1 μg. A targeted mass of a powder ranging from 1 to 30 μg was deposited on filters for gravimetric and elemental carbon (EC) analysis. The gravimetric mass was compared to the EC mass, and a regression model developed for each powder type. Additionally, the limit of detection (LOD) of the NIOSH Method 5040 for each powder type was determined. The regression models had significant slopes relative to zero for all powder types with all but carbon black demonstrating a statistical difference between the two methods. The LOD of NIOSH Method 5040 ranged from 4.5 for small-diameter MWCNTs to 31.8 μg for nickel-coated MWCNTs. Assuming a sample flow rate of 4.2 L/min and an 8-hour sample duration, the concentration-based LOD for NIOSH Method 5040 ranged from 2.2 μg/m3 for small-diameter MWCNTs to 15.8 μg/m3 for nickel-coated MWCNTs. These results indicate the analysis of EC is affected by the structure and elemental content of the CNTs. Additionally, based on the LOD determined for each powder type, the method may not be sufficient to assess exposures at and below the recommended exposure limit accurately without sampling durations longer than 8 hours. A second study used a laboratory-based system to evaluate an aethalometer response to carbon-containing nanomaterials including carbon black and MWCNTs. Concentrations ranging from 1 to 20 μg/m3 were generated to evaluate the device at concentrations expected in occupational settings. The concentration of the aerosol was measured by an aethalometer alongside a sample collected for EC analysis using NIOSH Method 5040. Additionally, NIOSH Method 7300 was used to determine the concentration of nickel during trials with a nickel-coated MWCNT to determine if the method along with the aethalometer can be used to assess metal-coated MWCNTs. A regression model was developed for each powder type, and the slopes for each were significant relative to zero. The LOD of the aethalometer ranged from 0.56 μg/m3 for nickel-coated MWCNTs to 7.2 μg/m3 for small-diameter MWCNTs. These results indicate the response of the aethalometer may be affected by particle structure and elemental content. NIOSH Method 5040 performed better than the aethalometer for all powder types except the nickel-coated MWCNT. Additionally, based on the LOD determined for each powder, an aethalometer may not be able to assess low-level exposures. In the third study, a mathematical model was used to predict the particle penetration and pressure drop of respirator filters with varying filter thickness, fiber diameter, solidity, and electrostatic charge. Particle penetration was determined experimentally for two different commercially available respirator filters against a sodium chloride aerosol using a scanning mobility particle sizer (SMPS). Optimized filter designs were developed using the model to minimize the pressure drop by adjusting the filter depth, fiber diameter, and solidity of the filter. The model and experimental data were used to maintain a 5% maximum penetration against nanoparticle exposures while minimizing breathing resistance. Model results indicated electrostatic charging played a significant role in improving collection efficiency of respirator filters while not increasing the breathing resistance of the filter. Filter thickness and solidity also played a key role in minimizing breathing resistance. Pressure drop decreased with decreasing solidity, however, the filter depth increased to maintain the collection efficiency of the filter. This increase in filter depth introduced a decision point of determining the practical implications of increased filter thickness on the end user. Filter depth increases dramatically as the solidity decreases below 0.20. The breathing resistance that corresponds to this design is heavily dependent on the face velocity and electrostatic charge of the filter. The electrostatic charge should be maximized during filter production as this was the dominant collection method for nanoparticle aerosols.
175

Företagens presentation av intellektuellt kapital : nu och då

Källman, Jennie, Arvidsson, Micaela January 2008 (has links)
<p> </p><p>Redovisningen är anpassad efter den gamla ekonomin och fyller därför inte dagens behov av redovisad information. Istället för att endast redovisa företagets materiella tillgångar behöver bland annat kunskapsföretag presentera osynliga tillgångar vilka utgör en stor del av företagens värde. Detta så kallade intellektuella kapital behöver framhävas i företagens finansiella rapporter för att intressenter ska kunna göra en rättvis bedömning av företaget. Problem uppstår vid värdering och redovisning av intellektuellt kapital eftersom begreppets definition är otydlig och därför uppfattas olika av olika personer. Problem uppstår även eftersom det inte finns några allmänt etablerade principer för hur värderingen och redovisningen ska gå till. Frågan är då hur olika företag har uppfattat begreppet och hur de har valt att presentera detta i sina rapporter. Syftet är att identifiera vilken information företag presenterar om intellektuellt kapital vid tre olika tidpunkter. Studien syftar också till att beskriva på vilket sätt företag valt att framhäva denna information. Resultatet visar att 17 av 32 företag inte har ändrat sin redovisningsteknik under en nioårsperiod. Bland resterande företag har valet av redovisningsteknik förändrats över tid. En skillnad är att de företag som år 1999 presenterade intellektuellt kapital genom en modell, har till år 2007 valt att ändra redovisningsteknik. Detta motiveras med att det antingen blivit för kostsamt för företaget eller att företaget fortfarande arbetar med modellen internt men har valt att inte presentera den i offentliga rapporter. Resultatet visar även att det är främst information om medarbetarna som presenteras i företagens rapporter. Det kan ses både vid jämförelse av företag sinsemellan och inom ett företag över tid. Att medarbetarna får ta störst plats kan bero på att de är grundstenen till de övriga delarna av det intellektuella kapitalet, och företagen vill därför framhäva att de innehar denna tillgång.</p><p> </p>
176

Företagens presentation av intellektuellt kapital : nu och då

Källman, Jennie, Arvidsson, Micaela January 2008 (has links)
Redovisningen är anpassad efter den gamla ekonomin och fyller därför inte dagens behov av redovisad information. Istället för att endast redovisa företagets materiella tillgångar behöver bland annat kunskapsföretag presentera osynliga tillgångar vilka utgör en stor del av företagens värde. Detta så kallade intellektuella kapital behöver framhävas i företagens finansiella rapporter för att intressenter ska kunna göra en rättvis bedömning av företaget. Problem uppstår vid värdering och redovisning av intellektuellt kapital eftersom begreppets definition är otydlig och därför uppfattas olika av olika personer. Problem uppstår även eftersom det inte finns några allmänt etablerade principer för hur värderingen och redovisningen ska gå till. Frågan är då hur olika företag har uppfattat begreppet och hur de har valt att presentera detta i sina rapporter. Syftet är att identifiera vilken information företag presenterar om intellektuellt kapital vid tre olika tidpunkter. Studien syftar också till att beskriva på vilket sätt företag valt att framhäva denna information. Resultatet visar att 17 av 32 företag inte har ändrat sin redovisningsteknik under en nioårsperiod. Bland resterande företag har valet av redovisningsteknik förändrats över tid. En skillnad är att de företag som år 1999 presenterade intellektuellt kapital genom en modell, har till år 2007 valt att ändra redovisningsteknik. Detta motiveras med att det antingen blivit för kostsamt för företaget eller att företaget fortfarande arbetar med modellen internt men har valt att inte presentera den i offentliga rapporter. Resultatet visar även att det är främst information om medarbetarna som presenteras i företagens rapporter. Det kan ses både vid jämförelse av företag sinsemellan och inom ett företag över tid. Att medarbetarna får ta störst plats kan bero på att de är grundstenen till de övriga delarna av det intellektuella kapitalet, och företagen vill därför framhäva att de innehar denna tillgång.
177

偷偷看嬰兒監視器創業計劃書 / Totokan Baby Monitor Business Plan

林佳樺, Lin, Shelley C.H. Unknown Date (has links)
Infant safety has always been a major concern for new parents and those with small children. Monitoring young infants while they are asleep with the dangers of Sudden Infant Death Syndrome (SIDS) or Apnea has always been a very important part of parenting. Not only are there a multitude of products that are designed and produced each year to ease the minds of new parents, but there are numerous laws and regulations with the focus of enforcing the safety of young children in moving vehicles. Many countries around the world have made strict laws enforcing rear facing car seats for young infants. This position is ensures that its precious cargo is in the safest position possible in the event of a car crash. Though safe, the rear facing position is not the most practical for parents to monitor their child while in the driver’s seat. It is difficult while in motion to check on your child to see if she has spit up, fallen asleep, or if her safety straps need to be readjusted while she is rear facing. This is where our product, Totokan Baby Monitoring Systems, can help ease the minds of parents. Designed for flexible usage and on-the-go parents; our product is wireless, portable, and durable. Totokan can be easily installed on the car head rest or attached wherever you need to monitor your child. Most importantly the image of your child is streamed directly to your smart phone. The convenience of this product allows this monitor to go where you go, whether it is a long road trip, a play date at a friend’s house, or a quick nap at the grandparents. The ultimate goal is for Totokan’s design to be easily portable and effortlessly set up for parents to take on-the-go.
178

Optimization of plastic scintillator thicknesses for online beta detection in mixed fields

Pourtangestani, Khadijeh 01 December 2010 (has links)
For efficient beta detection in a mixed beta gamma field, Monte Carlo simulation models have been built to optimize the thickness of a plastic scintillator, used in whole body monitor. The simulation has been performed using MCNP/X code and different thicknesses of plastic scintillators ranging from 150 to 600 um have been used. The relationship between the thickness of the scintillator and the efficiency of the detector has been analyzed. For 150 m thickness, an experimental investigation has been conducted with different beta sources at different positions on the scintillator and the counting efficiency of the unit has been measured. Evaluated data along with experimental ones have been discussed. A thickness of 300 um to 500 um has been found to be an optimum thickness for better beta detection efficiency in the presence of low energy gamma ray. / UOIT
179

IFMIF-LIPAc Beam Diagnostics. Profiling and Loss Monitoring Systems

Egberts, Jan 25 September 2012 (has links) (PDF)
The IFMIF accelerator will accelerate two 125mA continuous wave (cw) deuteron beams up to 40MeV and blasts them onto a liquid lithium target to release neutrons. The very high beam power of 10MW pose unprecedented challenges for the accelerator development. Therefore, it was decided to build a prototype accelerator, the Linear IFMIF Prototype Accelerator (LIPAc), which has the very same beam characteristic, but is limited to 9 MeV only. In the frame of this thesis, diagnostics devices for IFMIF and LIPAc have been developed. The diagnostics devices consist of beam loss monitors and interceptive as well as non-interceptive profile monitors. For the beam loss monitoring system, ionization chambers and diamond detectors have been tested and calibrated for neutron and γ radiation in the energy range expected at LIPAc. During these tests, for the first time, diamond detectors were successfully operated at cryogenic temperatures. For the interceptive profilers, thermal simulations were performed to ensure safe operation. For the non-interceptive profiler, Ionization Profile Monitors (IPMs) were developed. A prototype has been built and tested, and based on the findings, the final IPMs were designed and built. To overcome the space charge of accelerator beam, a software algorithm was written to reconstruct the actual beam profile.
180

Maintenance of the Quality Monitor Web-Application

Ponomarenko, Maksym January 2013 (has links)
Applied Research in System Analysis (ARiSA) is a company specialized in the development of the customer-specific quality models and applied research work. In order to improve the quality of the projects and to reduce maintenance costs, ARiSA developed Quality Monitor (QM) – a web application for quality analysis. QM application has been originally developed as a basic program to enable customers to evaluate the quality of the sources. Therefore, the business logic of the application was simplified and certain limitations were imposed on it, which in its turn leads to a number of issues related to user experience, performance and architecture design. These aspects are important for both application as a product, and for its future promotion. Moreover, this is important for customers, as end users. Main application issues, which were added to the maintenance list are: manual data upload, insufficient server resources to handle long-running and resource consuming operations, no background processing and status reporting, simplistic presentation of analysis results and known usability issues, weak integration between analysis back-ends and front-end. ­­­­­­­­­­­In order to address known issues and to make improvements of the existing limitations, a maintenance phase of QM application is initiated. First of all, it is intended to stabilize current version and improve user experience. It also needed for refactoring and implementation of more efficient data uploads processing in the background. In addition, extended functionality of QM would fulfill customer needs and transform application from the project into a product. Extended functionality includes: automated data upload from different build processes, new data visualizations, and improvement of the current functionality according to customer comments. Maintenance phase of QM application has been successfully completed and master thesis goals are met. Current version is more stable and more responsive from user experience perspective. Data processing is more efficient, and now it is implemented as background analysis with automatic data import. User interface has been updated with visualizations for client-side interaction and progress reporting. The solution has been evaluated and tested in close cooperation with QM application customers. This thesis describes requirements analysis, technology stack with choice rationale and implementation to show maintenance results.

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