Made available in DSpace on 2016-03-15T19:37:31Z (GMT). No. of bitstreams: 1 Rodrigo Cesar Ribeiro Miraglia.pdf: 2147088 bytes, checksum: 67087392fe4b03bb24d9a164fd92ceed (MD5) Previous issue date: 2010-08-20 / Fundo Mackenzie de Pesquisa / Sensors based on optical fibers are being increasingly used in hostile environments for measuring pressure, temperature, stress, chemical and biological parameters, etc. These sensors have the advantage of having reduced size and weight, immunity to electromagnetic interference, of being chemically inert, and also allowing the distributed measurement of the respective parameter along the fiber. Microstructured optical fibers have characteristics that are relevant to sensing applications, such as freedom of design of their internal structure obtained by varying the diameter of the holes and the distances between them, among other parameters, which is not applicable in conventional optical fibers. The present work aims to use a microstructured optical fiber as a distributed sensor for hydrostatic pressure, using the POTDR (Polarization Optical Time-Domain Reflectometry) and the OFDR (Optical Frequency-Domain Reflectometry) measurement techniques. The application of hydrostatic pressure on the fiber changes its birefringence and, consequently, the evolution of the states of polarization, which is the parameter monitored by the techniques. By monitoring the changes of these states, it is possible to infer the changes in applied pressure. The study is undertaken via simulations and analysis, both performed in the software MatLab. / Sensores baseados em fibras ópticas vêm sendo cada vez mais utilizados em ambientes hostis para medição de pressão, temperatura, stress, análise química e biológica, etc. Esses sensores têm a vantagem de possuírem tamanho e peso reduzidos, imunidade à interferência eletromagnética, de serem quimicamente inertes, e também permitirem a medição distribuída do parâmetro a ser analisado ao longo da fibra. As fibras ópticas microestruturadas possuem características relevantes na aplicação de sensoriamento, tal como a liberdade de construção de sua estrutura interna variando o diâmetro dos buracos e a distância entre eles, entre outros parâmetros, que não são aplicáveis em fibras ópticas convencionais. Este trabalho tem como objetivo estudar uma fibra óptica microestruturada como sensor distribuído de pressão hidrostática, utilizando as técnicas de medição POTDR (Polarization Optical Time-Domain Reflectometry) e OFDR (Optical Frequency-Domain Reflectometry). A aplicação de pressão hidrostática sobre a fibra altera sua birrefringência e, consequentemente, a evolução do seu estado de polarização, sendo este último o parâmetro monitorado pelas técnicas. Analisando-se a mudança deste estado, pode-se inferir a mudança de pressão aplicada. O estudo é realizado através de simulações e análises efetuadas no software MatLab.

Anal acoustic reflectometry (AAR) is a technique that is currently under investigation for the assessment of faecal incontinence. It uses reflected sounds waves to measure cross sectional area at different pressures leading to a profile of the anal canal, and in particular the high pressure zone of the anal sphincters. The cross sectional area from the high pressure zone is then plotted on a graph to give seven characteristic parameters. AAR has been shown to be reproducible and reliable, able to distinguish between continence and incontinence, correlate with the severity of incontinence and able to discriminate between the three patterns of incontinence (urge, passive and mixed). Opening pressure has been shown to be an independent predictor of success with peripheral nerve evaluation, the trial period before sacral nerve stimulation. This thesis aimed to validate AAR against manometry and explore its physiological and clinical potential. A retrospective analysis of 265 patients who had undergone AAR was undertaken in order to develop a surrogate marker for anal canal length. The surrogate marker did find the expected difference between men and women but this was not clinically significant. Furthermore, the surrogate marker was unable to differentiate between incontinence and continence. A technical limitation (Gibbs phenomenon) of AAR was subsequently shown to explain this unexpected result. Prior manometry could possibly interfere with the interpretation of AAR, and therefore a prospective randomised cohort study of 30 patients was conducted to assess two orders of data collection. Reassuringly it does not matter which one of these investigations is undertaken first. In order to test the hypothesis that the greater the challenge to the anal sphincter, the greater the response, the effect of two rates of anal canal stretch was investigated in a prospective randomised cohort study of 50 patients with faecal incontinence. No difference was found between normal or fast rates of AAR. This study has validated a faster method of AAR that can be used alongside manometry in any order. A pudendal nerve block was used to investigate whether AAR assesses primarily internal or external sphincter function in a prospective cohort study of 15 patients using both AAR and manometry. Bilateral pudendal nerve block reduced the function of the external anal sphincter but had no effect on the internal sphincter using both techniques. This study suggests that AAR at rest is predominately an investigation of the internal anal sphincter. A prospective study of 30 patients with faecal incontinence was carried out to establish if AAR can predict the outcome from posterior tibial nerve stimulation. Posterior tibial nerve stimulation improved rectal sensation, manometry squeeze pressures, quality of life, severity of incontinence and was more effective for patients with urge incontinence. A variety of demographic, clinical and physiological measures were unable to predict the success of posterior tibial nerve stimulation. The results presented in this thesis suggest that the full clinical potential of AAR has yet to be realised and it will be necessary to compare it with high resolution anal manometry in the future. Progress in this field would be greatly facilitated by establishing the normal values for this technique and the development of a robust AAR assessment of the external anal sphincter.

Diplomová práce nastiňuje problémy spojené s výrobou a analýzou tenkých vrstev DLC:H. Tyto vrstvy jsou ve středu zájmu mnoha vědeckých pracovníků již po několik desetiletí. V současné době existuje mnoho technik pro přípravu a analýzu. Příprava DLC vrstev má zásadní vliv na jejich vlastnosti a možnosti použití. Je zde mnoho kritérií jak vrstvy posuzovat. V této práci jsou studovány vlastnosti DLC:H vrstev připravených na substrát krystalického křemíku metodou RF-PECVD a následně jsou studovány mechanické, tribologické a optické vlastnosti. Jsou zde využity techniky jako XPS, Ramanova spektroskopie, reflektometrie, měření tvrdosti a adheze. Část práce se zabývá modelováním DLC z prvních principů. Pro tento účel je využito prvoprincipiálního programu Abinit který je šířen pod GPL. Je studována otázka přípravy vstupních dat s ohledem na konvergenci výsledků. Pozornost je také věnována výpočtu vibračních spekter ve středu Brillouinovy zóny ( bod) a celkové hustotě elektronových stavů clusteru DLC v supercele tvaru krychle. Tyto výsledky mohou být porovnány s experimentálně získanými daty z Ramanovy spektroskopie, respektive z XPS spektra valenčního pásu

The work deals with a technique of imaging spectroscopic reflectometry developed at The Institute of Physical Engineering, Brno University of Technology. The technique is well suited for characterization of samples non–uniform along their surfaces. The technique is primarily used for optical characterization of thin films. First part of the work is focused on basic physical principles of the technique and on ways in which measurement data are obtained. It contains a basic description of evaluating methods and a basic concept of an imaging spectroscopic reflectometer with a description of main parts of such a device. The main part of the work is focused on a description of two devices which were built at The Institute of Physical Engineering together with a description of some of upgrades which were implemented to these devices during their development. A description of measurements done with the two devices is also included. Last part of the work is then focused on further development of the technique. Intention of possible evolution of the technique to imaging spectroscopic ellipsometry is proposed.

[pt] Diante do crescimento do interesse pelos amplificadores Raman faz-se necessário um estudo mais detalhado destes. Uma técnica tradicionalmente já utilizada para analise de atenuação em enlaces, a reflectometria óptica no domínio do tempo, é empregada de maneira inovadora neste trabalho para a observação da amplificação Raman distribuída. O objetivo principal deste trabalho não é a analise de amplificadores Raman, mas sim a apresentação desta técnica como nova ferramenta observação do ganho Raman distribuído em fibras ópticas. / [en] Due to increased interest in Raman amplifiers, a more detailed study of them is required. A technique traditionally used for analysis of attenuation on optical links, time domain optical reflectometry, is used in an innovative way in this work for observation of distributed Raman amplification. The main objective of this work in not the analysis of Raman amplifiers, but the introduction of this technique as a new tool for the observation of distributed Raman gain in optical fibers.

The paper describes the Rossendorf Beamline (ROBL) built by the Forschungszentrum Rossendorf at the ESRF. ROBL comprises two different and independently operating experimental stations: a radiochemistry laboratory for X-ray absorption spectroscopy of non-sealed radioactive samples and a general purpose materials research station for X-ray diffraction and reflectometry mainly of thin films and interfaces modified by ion beam techniques. The radiochemistry set-up is worldwide an unique installation at a modern synchrotron radiation source.

ectroscopic reflectometry is measurement technique that enables the study of the thickness and refractive index of thin layers. This thesis deals with its use for the study of lubrication films within EHD contact and verifies a new approach suggested in recent publications. It is focused on the development of an optical arrangement and mathematical model for the lubrication film thickness measurement within the entire EHD contact. This technique brings the possibility to study the pressure distribution within the contact area through the evaluation of changes in lubricant refractive index.

Fosfoniumjonvätskor har tidigare studerats som potentiella nya avancerade smörjmedel på grund av sina unika fysikaliska egenskaper och fördelar jämfört med både traditionella smörjmedel och andra typer av jonvätskor. Dessa studier har uppvisat lovande resultat med avseende på reducering av nötning och friktion såväl som kontroll av dessa parametrar med en pålagd elektrisk potential. En multitud av frågor återstår dock att besvara om strukturering av jonarter i den skyddande gränssnittfilmen som bildas och kopplingen mellan strukturella drag i de involverade jonarterna och den skyddande funktionen av gränsnittsfilmen. I denna avhandling studeras ett flertal mono och dikatjon fosfoniumjonvätskor med icke halogena bis(oxalato)borat anjoner såväl som en binär blandning av dessa av intresse som nya avancerade smörjmedel och som additiv med neutronreflektometri vid ett elektrifierat elektrodgränssnitt med syfte att studera strukturella egenskaper av den gränsnittsfilmen som bildas samt elektroresponsiviteten av denna film. Resultaten av detta uppvisar egenskaper om både struktureringen av jonarterna och deras elektroresponsivitet av intresse för den fortsatta utvecklingen av avancerade smörjmedelslösningar med fosfoniumjonvätskor. / Phosphonium ionic liquids(ILs) has previously been investigated as advanced novel lubricants because of their physical unique properties and advantages compared to traditional lubricants and other ILs. These studies have showed promising results in wear and friction reduction as well as the tribotronic control of those properties. A multitude of questions however remain about the interfacial structuring of these protective films and the connection between structural features in the ionic species to the protective function of the interfacial film.In this thesis multiple non-halogenated mono- and di-cationic phosphonium ionic liquids with bis(oxalato)borate anion as well as a binary mixture of interest for advanced neat lubricants or additives has been studied by neutron reflectometry at an electrified electrode interface to investigate interfacial properties and electroresponsiveness of the species. The results elucidate properties of the structuring of key to the further development of phosphonium ILs for use in advanced lubrication formulations.

Here the nature of gas phase processes and their implications for flow and transport were examined using a pilot-scale, 2-dimensional, laboratory tank instrumented for direct, in situ trapped gas measurements. Experimental conditions mimicked an unconfined, homogeneous sand aquifer with horizontal flow. Key areas of investigation included i) trapped gas dissolution following a water table fluctuation; and ii) gas phase dynamics within a hydrocarbon plume experiencing dissolved gas production via biodegradation. In the first experiment, dissolution occurred as a diffuse, wedge-shaped front propagating down-gradient in the tank over time, with enhanced dissolution at depth. Front advancement at the deepest monitoring point was 4.1 - 5.7x faster. This dynamic, depth-dependent pattern was mainly attributed to increased dissolved gas solubility. An estimated 12% increase in quasi-saturated hydraulic conductivity (Kqs) also contributed to greater dissolution at depth. Overall, the dissolution front near the water table advanced 1 m down-gradient in 344 days, suggesting that gas trapped shallowly will likely persist for significant periods of time. The utility of total dissolved gas pressure sensors for simple in-well measurements to detect trapped gas and monitor its dissolution were also demonstrated. During the second experiment, biodegradation occurred under variable redox conditions, ranging from denitrification to methanogenesis. Significant in situ increases in trapped gas were observed within the tank over 330 days. Maximum gas saturations never exceeded 27% of pore volume even during continued dissolved gas production, indicating ebullition upon reaching a gas phase mobilization threshold. Consequently, associated reductions in Kqs were restricted to a factor of 2 or less, but still appeared to alter the groundwater flow field. While trapped gas increases within the biodegradation plume were expected, declines in gas saturations were also observed. Thus, the overall pattern of trapped gas growth exhibited high spatial and temporal variability. Influencing factors included changes in hydrocarbon inputs and microbial controls on redox zonation, in addition to ebullition and changes in groundwater flow; emphasizing that gas phase growth in contaminant plumes will be highly complex and dynamic in the natural systems. Given the impacts on hydraulic conductivity, and the fate and transport of volatile compounds, an improved understanding of quasi-saturated conditions will be beneficial for various groundwater applications, from recharge and paleoclimate studies to site characterizations and remediation strategies. / Dissertation / Doctor of Philosophy (PhD)

This dissertation proposes a learning-based, physics-aware soil moisture (SM) retrieval algorithm for NASA’s Cyclone Global Navigation Satellite System (CYGNSS) mission. The proposed methodology has been built upon the literature review, analyses, and findings from a number of published studies throughout the dissertation research. Namely, a Sig- nals of Opportunity Coherent Bistatic scattering model (SCoBi) has been first developed at MSU and then its simulator has been open-sourced. Simulated GNSS-Reflectometry (GNSS-R) analyses have been conducted by using SCoBi. Significant findings have been noted such that (1) Although the dominance of either the coherent reflections or incoher- ent scattering over land is a debate, we demonstrated that coherent reflections are stronger for flat and smooth surfaces covered by low-to-moderate vegetation canopy; (2) The influ- ence of several land geophysical parameters such as SM, vegetation water content (VWC), and surface roughness on the bistatic reflectivity was quantified, the dynamic ranges of reflectivity changes due to SM and VWC are much higher than the changes due to the surface roughness. Such findings of these analyses, combined with a comprehensive lit- erature survey, have led to the present inversion algorithm: Physics- and learning-based retrieval of soil moisture information from space-borne GNSS-R measurements that are taken by NASA’s CYGNSS mission. The study is the first work that proposes a machine learning-based, non-parametric, and non-linear regression algorithm for CYGNSS-based soil moisture estimation. The results over point-scale soil moisture observations demon- strate promising performance for applicability to large scales. Potential future work will be extension of the methodology to global scales by training the model with larger and diverse data sets.