The purpose of this work was to develop an automated method of measuring fiber diameters of electrospun scaffolds from scanning electron microscopy images of these scaffolds. Several automated methods were developed and evaluated by comparison to known values and data obtained via the standard manual method. Simulated images with known diameters were used as test images to evaluate the accuracy of each measurement technique. Eight scanning electron microscopy images were also used for the evaluation of the automated methods compared to the standard manual method. All diameter measurements were made in pixels. Five new automated methods coded in MATLAB were developed. The five methods varied the approach of identifying edges of fibers as well as assigning edges to single fibers and calculating the distance between edges assigned to the same fiber. One-way analysis of variance and the Tukey-Kramer tests were performed for comparison of all methods per image. The Custom Canny Slopes automated method was shown to accurately approximate the mean diameters in ten simulated images as well as microscopy image of real scaffolds (p<0.05).

The purpose of this study was to construct a flowmeter that could accurately measure the hydraulic permeability of electrospun fibrinogen scaffolds, providing insight into the transport properties of electrospun scaffolds while making the measurement of their topographical features (fiber and pore size) more accurate. Three different concentrations of fibrinogen were used (100, 120, and 150mg/ml) to create scaffolds with three different fiber diameters and pore sizes. The fiber diameters and pore sizes of the electrospun scaffolds were analyzed through scanning electron microscopy and image analysis software. The permeability of each scaffold was measured and used to calculate permeability-based fiber diameters and pore sizes, which were compared to values obtained through image analysis. Permeability measurement revealed scaffold permeability to increase linearly with fibrinogen concentration, much like average fiber diameter and pore size. Comparison between the two measurement methods proved the efficacy of the flowmeter as a way to measure scaffold features.

Student Number : 9104308Y - Msc Eng research report - School of Mining Engineering - Faculty of Engineering and the Built Environment / African Explosives Limited (AEL) is involved with the Hybrid Stress Blast Model (HSBM) project in the characterisation of its bulk explosives and part of this involves the collection of unconfined detonation velocities (VoD). Historical methods of unconfined VoD measurements and earlier measurements taken for the HSBM project did not attribute significance to the strength of the light containment media used, which was either cardboard or PVC, in various wall thicknesses. The main focus of this exercise was to investigate this significance and to make recomendations to the HSBM on the choice of pipes for future tests. ANFO was used in order to avoid complexities of manufacturing and density variation, which arise with emulsion explosives. Plastic sleeves were used as a control in defining a medium of negligible confinement in order to compare the results in PVC and cardboard pipes. The cardboard pipes selected had wall thicknesses of 2mm and 4mm, while the PVC pipes had pressure ratings of 4 Bar and 9 Bar with wall thicknesses from 1.5mm to 8.5mm. The inner diameters ranged between 45mm and 253mm. The following findings have been made in this report. - Plastic sleeves were not effective in comparing the effects of confinement, but the results suggests that thin walled carboard pipes are probably very close to unconfined, even near the critical diameter. - PVC pipes affect VoD more than cardboard pipes and the confinement provided by both types of pipes increases with their wall thickness. - Critical diameter increases with weaker confinement and vice versa. - VoDs in the different types of confinement converge as diameter increases. - Future unconfined VoD tests should take cognisance of the findings of this project. A similar confinement investigation would be benificial to determine whether similar trends prevail with Emulsion and Emulsion-ANFO blend explosives. However if such an evaluation is not conducted, the minimum requirements for further tests should be to apply the confinement and diameter relationships as determined for ANFO during this investigation.

Oligonucleotides may become a new class of therapies with the potential of curing many today untreatable diseases. Oligonucleotides becomes increasingly more difficult to separate with an increase in length since the relative difference in retention of these very similar compounds becomes increasingly smaller. Therefore, coelution of impurities formed during synthesis may result in insufficient purity, which is necessary for therapeutic treatments. Oligonucleotides are also relatively large biomolecules, possibly consisting of hundreds of nucleotides. As a result, oligonucleotides may have limited diffusion through the stationary phase pores which affects separation performance. Surprisingly few studies have be published in this research area and a wider knowledge in how this affects separation is needed. In this master thesis, separation of deoxythymidine oligonucleotides with 5-30 mers in length were separated with 60, 100, 200 and 300 Å pore size reversed phase C4 columns. It was concluded that pore size resulted in more restricted diffusion if insufficient pore size was used. Poor peak performance was also observed with too large pore sizes which lead to less efficient separations.

Este trabalho teve por objetivo avaliar modelos de taper para Corymbia citriodora com 55 meses de idade no Sul do estado do Tocantins. Foram utilizadas 35 árvores amostras cubadas com a obtenção dos diâmetros com e sem casca nas posições 0,2 m, 0,4 m, 0,7 m, 1,3m, 2,7 m e, a partir deste ponto em diante a cada 2 metros até um diâmetro em torno de 1,0 cm com casca. Para avaliação dos modelos utilizou-se as seguintes estatísticas: coeficiente de determinação ajustado, erro padrão da estimativa, distribuição gráfica dos resíduos, média dos desvios absolutos, desvio padrão das diferenças, soma dos quadrados dos resíduos relativos, média dos desvios percentuais, raiz quadrada do erro médio, viés e coeficiente de correlação múltipla. Além disso, avaliou-se a viabilidade da utilização da variável binária “Tx” no ajuste simultâneo para dados com e sem casca. Concluiu-se, portanto, que o modelo de Muhairwe I obteve os melhores resultados para as estatísticas utilizadas, bem como a confirmação da viabilidade em se obter o ajuste diamétrico com uma só equação através da inclusão da variável Tx. / The objective of this study was to evaluate taper models for Corymbia citriodora at 55 months of age in the southern state of Tocantins. Thirty-five trees were used to obtain the diameters with and without bark at the positions 0.2 m, 0.4 m, 0.7 m, 1.3 m, 2.7 m and from this point forward every 2 meters to a diameter of about 1.0 cm in bark. For the evaluation of the models, the following statistics were used: adjusted coefficient of determination, standard error of the estimate, graphical distribution of the residuals, mean absolute deviations, standard deviation of the differences, sum of the squares of relative residues, mean of the percentage deviations, square root of mean error, bias and multiple correlation coefficient. In addition, we evaluated the feasibility of using the binary variable "Tx" in the simultaneous adjustment for data with and without shell. It was concluded, therefore, that the Muhairwe I model obtained the best results for the statistics used, as well as the confirmation of the feasibility in obtaining the diametric adjustment with a single equation through the inclusion of the variable Tx.

Several Arctic council reports conclude that oil spills are the most significant threat to the Arctic ecosystem. Some studies have shown that in-situ burning (ISB) of oil spills over water can remove more than 90% of the oil, and is the most promising technology for an efficient response to oil spills in the Arctic region. The definition of "In situ" is intentional, controlled burning of oil in place (i.e., without extracting or removing the oil first). Earlier studies [Bellino (WPI 2012), Farahani, (WPI 2014)] have investigated burning behavior of crude oil on ice, similar to what one would expect in sea-ice or bare lake ice conditions. The focus of the current study is to investigate the burning behavior of crude oil in snow, similar to oil spills in snow-covered land, or in snow covered sea ice in the Arctic. Understandably, due to the difference in packing density between ice/water and snow, the parameters that influence burning behavior of oil in snow are different compared to burning oil in the sea or ice conditions. The current experimental study shows that the snow behaves as a porous medium, and depending on the porosity and volume of the oil spill, two extreme behaviors are exhibited. In the case of an oil spill on snow with low porosity, the oil sinks easily to the bottom, and the burning involves, significant thermo capillary effects enabling the oil to rise up and burn. On the other hand, if the snow is less porous, most of the oil layer remains on the surface, approaching the case of an ice bed. However, the melting of snow due to flame heat flux causes a circulating flow pattern of the oil, whereby the hot layer at the surface moves down and comes back up due to capillary action. These processes, which have not been observed in the earlier studies, are physically explained in this study. The implications to overall efficiency of the burning process, which represents the amount of crude oil left in the snow after the burning process is discussed. The results will ultimately improve the strategies and the net environmental benefit of, and by it the success of, oil clean-up after an accidental spill on snow.

Cette thèse a pour objectif d'apporter un regard nouveau sur les principales caractéristiques physiques du Soleil. Avant le développement de l'astrophysique, l'étude d'un astre concernait surtout ses propriétés géométriques. La mesure précise du diamètre du Soleil a été entreprise dès l'antiquité et représente un des plus vieux problèmes en astrophysique. Une partie de cette thèse est consacrée à l'étude du diamètre solaire et de ses variations au cours du temps. Un des objectifs est de déterminer si le diamètre du Soleil varie en fonction de l'activité solaire. Les données acquises par les instruments de la mission PICARD ont été utilisées afin d'essayer de répondre à cette question. Cette thèse porte aussi sur la détermination absolue de l'aplatissement solaire et de ses variations au cours du cycle 24. Cette étude s'est basée sur l'exploitation des mesures acquises par deux télescopes spatiaux (PICARD/SODISM et SDO/HMI). Les mesures de l'aplatissement solaire sont importantes et permettent de valider les hypothèses physiques mises en œuvre dans les modèles du Soleil. Cette thèse consiste aussi à déterminer la valeur absolue de l'éclairement solaire total et de sa variabilité au cours du temps. L'éclairement solaire total représente une entrée essentielle pour tous les modèles climatiques. Sa détermination précise est donc fondamentale. La valeur absolue de l'éclairement solaire total a été obtenue à partir des mesures réalisées par le radiomètre PICARD/SOVAP. Le dernier chapitre de cette thèse est dédié à l'étude de l'éclairement solaire dans l'ultraviolet et de ses variations au cours du cycle 24. Cette étude s'appuie sur les mesures réalisées par le spectromètre SOLAR/SOSLPEC à bord de la station spatiale internationale. La variabilité du rayonnement ultraviolet au cours d'un cycle solaire (environ 10% à 200 nm) est beaucoup plus élevée que celle de l'éclairement solaire total (environ 0.1%). La détermination précise de la variabilité ultraviolet est donc très importante. Il est aussi de plus en plus évident que les variations de l'éclairement solaire dans l'ultraviolet jouent un rôle significatif au niveau de la chimie de l'atmosphère et du climat de la Terre. Les résultats obtenus au cours de cette thèse montrent l'intérêt de réaliser des mesures précises dans l'ultraviolet au cours d'un cycle solaire de 11 ans. / This thesis aims to highlight a new vision on the main physical characteristics of the Sun. Before the development of astrophysics, the study of a star mainly concerned its geometrical properties. The accurate measurement of the solar diameter was carried out since the antiquity and represents one of the oldest problems in astrophysics. Part of this thesis is devoted to the study of the solar diameter and its variation over time. One of the objectives is to determine whether the diameter of the Sun varies with the solar activity. Data acquired by the PICARD mission instruments were used to try to answer this question. This thesis also deals with the absolute determination of the solar oblateness and its variation during the cycle 24. This study was based on the use of the measurements acquired by two space-based telescopes (PICARD/SODISM and SDO/HMI). The solar oblateness measurements are important and allow to validate the physical hypotheses implemented in the solar models. This thesis also consists to determine the absolute value of the total solar irradiance and its variability over time. The total solar irradiance is an essential parameter for all climate models. Its accurate determination is therefore fundamental. The absolute value of the total solar irradiance was obtained from the measurements carried out by the PICARD/SOVAP radiometer during the solar cycle 24. The last chapter of this thesis is devoted to the study of the solar irradiance in the ultraviolet and its variation during the solar cycle 24. This study is based on the measurements carried out by the SOLAR/SOSLPEC spectrometer on board the International Space Station. The variations of the ultraviolet radiation during a solar cycle (10% at 200 nm for a strong solar cycle) are much higher than the variations of the total solar irradiance (0.1%). The accurate determination of the ultraviolet solar irradiance is therefore very important. It is also increasingly evident that the variations of the solar irradiance in the ultraviolet play a significant role in the chemistry of the Earth's atmosphere and climate. The results obtained during this thesis show the interests to perform accurate measurements in the ultraviolet during a solar cycle of about 11 years. Through this work, we bring a new perspective with respect to the absolute value of the main solar parameters.

Este trabalho apresenta um estudo experimental acerca da influência da razão de espaçamento e da intensidade de turbulência no escoamento biestável. É estudado o escoamento sobre dois cilindros dispostos lado a lado, para o canal aerodinâmico com intensidade de turbulência inferior a 1%, para o canal aerodinâmico com grade promotora de turbulência com intensidade de turbulência de 8 a 7%, e para uma seção do canal aerodinâmico sem paredes laterais. A técnica experimental aplicada consiste na medição das flutuações de velocidade no canal aerodinâmico utilizando a técnica da anemometria de fio quente. As medições são realizadas com duas sondas, uma fixa e outra móvel que foi posicionada em seis pontos diferentes do escoamento. Os dados medidos são tratados através de ferramentas estatísticas, análise espectral e transformadas de ondaletas. Os resultados confirmam a existência do fenômeno da biestabilidade e mostram como o fenômeno sofre alterações quando exposto às condições de maior intensidade de turbulência e redução da razão de bloqueio pela retirada das paredes laterais em uma seção do canal. Para a condição de maior intensidade de turbulência, os resultados mostram que as trocas de modo se intensificam, e em alguns dos pontos de medição os sinais referentes à sonda móvel não apresentam características de biestabilidade. Para o caso sem paredes laterais, os sinais apresentam características de biestabilidade até o momento em que as paredes são removidas. / This work presents an experimental study, about the influence of the pitch to diameter ratio and the turbulence intensity on a bistable flow. The flow through two cylinders side-by-side is studied in an aerodynamic channel with turbulence intensity lower than 1%, in an aerodynamic channel with a turbulence grid, that increased the turbulence intensity to about 8 to 7%, and a section of the aerodynamic channel without lateral walls. The experimental technique consists in the measurements of the fluctuating velocities in the aerodynamic channel, using hot wire anemometry. The measurements are performed with two probes, one static, and one movable, positioned in six different points of the flow. The acquired data are analysed through statistical, spectral and wavelet tools. The results confirmed the occurrence of the bistable phenomenon and shows how it behaves when exposed to different conditions of turbulence intensity, and reduction of the blockage ratio aspect due to removal of the lateral walls of a channel section. The results for the higher turbulence intensity condition shows that the switches are intensified, some data resulting of the measurements of the second probe, do not show bistable characteristics. In the no-walls section case, the signals showed bistable features, until the moment the walls were removed.

A armazenagem em fazenda necessita ser expandida de modo a propiciar um melhor equilíbrio de fluxos e funções entre as etapas da rede armazenadora. No Brasil, embora não se disponha de números exatos, sabe-se que armazenagem na fazenda é mínima, sendo estimada em torno de 4% a 7%, dependendo da região. Em geral, os silos utilizados para a armazenagem em fazenda apresentam baixa relação entre a altura do silo e o seu diâmetro ou lado (0,75 a 1,5) e fundo plano. Podem ser construídos com os mais diversos materiais, como concreto, madeira, argamassa armada etc., mas a predominância é a utilização de silos metálicos em chapa de aço ondulada. Apesar da intensa utilização destas unidades em todo o mundo, e serem as mais produzidas pela indústria, a previsão das pressões devidas ao produto armazenado é ainda divergente entre os pesquisadores e normas existentes. Este trabalho foi realizado em duas etapas: teórica e experimental. Na parte teórica, deu-se ênfase à análise comparativa das principais teorias e normas estrangeiras. Na parte experimental, foram feitos ensaios diretos em um silo protótipo com relação h/d=0,98 e um silo piloto para relações h/d=0,98, 1,25 e 1,49, ambos de chapa de aço ondulada, para obtenção das pressões horizontais na parede e verticais no fundo plano. Com base nos resultados experimentais propõe-se modelos empíricos para a determinação das pressões horizontais e verticais no fundo plano do silo para esse tipo de unidade armazenadora. Também determinou-se experimentalmente o valor do parâmetro K, concluindo-se que a formulação de Hartmann é a mais indicada para silos metálicos de chapa de aço ondulada. / The farm storage must be expanded in order to offer a better balance of flows and functions among the stages of the storage system. In Brazil, it is known that storage in the farms is only about 4% to 7%, depending on the region. In general, the silos used for farm storage presents low ratio between the height of the silo and its diameter or side (0,75 to 1,5) and flat bottom. They can be built with different structural materials, as concrete, wood, ferrocement, etc., but the material predominance is corrugated steel. In spite of the intense use of these units all over the world, and its industry production, the pressures due the stored product is still divergent between the researchers and existent codes. This work was accomplished in two stages: theoretical and experimental. The theoretical part corresponds to the comparative analysis of the main theories and foreign codes. The experimental part corresponds to load tests using pressure cells in a silo prototype of relationship h/d=0,98 and a pilot silo for relationships h/d=0,98, 1,25 and 1,49, both of corrugated steel, for obtaining of the horizontal wall pressures and vertical pressures in the flat bottom. Based in the experimental results empiric models for the determination of the horizontal and vertical pressures in the bottom are proposed. The value of the parameter K, was also experimentally determined and the results showed that the formulation of Hartmann is the most suitable for metallic silos of corrugated steel plates.

The soil-structure interaction models associated with laterally loaded deep foundations have typically been based on load tests involving relatively small diameter foundations. The lateral soil resistance for larger diameter foundations has been assumed to increase linearly with diameter; however, few, if any load tests have been performed to confirm this relationship. To better understand the lateral resistance of large diameter deep foundations in sand, a series of full scale, cyclic, lateral load tests were performed on two 1.2 m diameter drilled shafts and a 0.324 m diameter steel pipe pile in sand. Although the tests involve two different foundation types, the upper 2.4 m of the profile, which provides the majority of the lateral resistance, consists of sand compacted around both foundation types. Therefore, these test results make it possible to evaluate the effect of foundation diameter on lateral soil resistance. The drilled shafts were first loaded in one direction by reacting against a fifteen-pile group. Subsequently a load test was performed in the opposite direction by reacting against a 9-pile group. The soil profile below the 2.4 m-thick layer of compacted sand consisted of interbedded layers of sand and fine-grained soil. For the drilled shaft load tests, pile head deflection and applied load were measured by string potentiometers and load cells, respectively. Tilt was also measured as a function of depth with an inclinometer which was then used to calculate deflection and bending moment as a function of depth. For the pipe pile, deflection and applied load were also measured; however, bending moment was computed based on strain gauges readings along the length of the pile. The lateral response of the drilled shafts and pipe pile were modeled using the computer programs LPILE (Reese et al., 2000), SWM6.0 (Ashour et al., 2002), and FB-MultiPier Version 4.06 (Hoit et al., 2000). Comparisons were made between the measured and computed load-deflection curves as well as bending moment versus depth curves. Soil parameters in the computer programs were iteratively adjusted until a good match between measured and computed response of the 0.324 m pipe pile was obtained. This refined soil profile was then used to model the drilled shaft response. User-defined p-multipliers were selected to match the measured results with the calculated results. On average very good agreement was obtained between measured and computed response without resorting to p-multipliers greater than 1.0. These results suggest that a linear increase in lateral resistance with foundation diameter is appropriate. LPILE typically produced the best agreement with measured response although the other programs usually gave reasonable results as well. Cyclic loading generally reduced the lateral resistance of the drilled shafts and pile foundation by about 20%.