Medium density fiberboard (MDF) production uses thermomechanically refined fiber processed under shear with high pressure steam. The industry evaluates fiber quality with visual and tactile inspection, emphasizing fiber dimensions, morphology, and bulk density. Considering wood reactivity, the hypothesis is that a variety of chemical and physical changes must occur that are not apparent in visual/tactile inspection. An industry/university cooperation, this work studies effects of refining energy (adjusted by refiner-plate gap) on fiber: size, porosity, surface area, surface and bulk chemistry, fiber crystallinity and rheology, and fiber interaction with amino resins. The intention is to reveal novel aspects of fiber quality that might impact MDF properties or process control efficiency, specific to a single industrial facility. In cooperation with a North American MDF Douglas fir plant, two refining energies were used to produce resin and additive-free fibers. Refining reduced fiber dimensions and increased bulk density, more so at the highest energy. Thermoporosimetry showed increases in sub-micron scale porosity, greatest at the highest energy. Mercury intrusion porosimetry (MIP) revealed porosity changes on a higher dimensional scale. Brunauer-Emmett-Teller gas adsorption and MIP showed that refining increased specific surface area, more so at the highest energy. Inverse gas chromatography showed that the lowest refining energy produced surfaces dominated by lignin and/or extractives. The highest energy produced more fiber damage, revealing higher energy active sites. A novel rheological method was devised to study fiber compaction and densification; it did not distinguish fiber types, but valuable aspects of mechano-sorption and densification were observed. Refining caused substantial polysaccharide degradation, and other degradative effects that sometimes correlated with higher refining energy. Lignin acidolysis was detected using nitrobenzene oxidation, conductometric titration of free phenols, and formaldehyde determination. Formaldehyde was generated via the C2 lignin acidolysis pathway, but C3 cleavage was the dominant lignin reaction. Observations suggested that in-line formaldehyde monitoring might be useful for process control during biomass processing. According to rheological and thermogravimetric analysis, lignin acidolysis was not accompanied by repolymerization and crosslinking. Lignin repolymerization must have been prevented by the reaction of benzyl cations with non-lignin nucleophiles. This raises consideration of additives that compete for lignin benzyl cations, perhaps to promote lignin crosslinking and/or augment the lignin network with structures that impart useful properties. Fiber/amino resin interactions were studied with differential scanning calorimetry (DSC) and X-ray diffraction (XRD). All fiber types, refined and unrefined, caused only a slight increase in melamine-urea-formaldehyde (MUF) resin reactivity. Generally, all fiber types decreased the enthalpy of MUF cure, suggesting fiber absorption of small reactive species. But DSC did not reveal any dependency on fiber refining energy. According to XRD, all fiber types reduced crystallinity in cured MUF, more so with refined fiber, but independent of refining energy. The crystallinity in cured urea-formaldehyde resin was studied with one fiber type (highest refining energy); it caused a crystallinity decrease that was cure temperature dependent. This suggests that resin crystallinity could vary through the thickness of an MDF panel. / PHD / Medium density fiberboard (MDF) is a wood-based composite which is widely used for making kitchen cabinets and furniture. In the process of making MDF, wood particles are softened under steam pressure and under high temperature and pressure, inside a refiner, mechanically cut into wood fibers. Wood fibers are then mixed with adhesive and additives then hot-pressed and form the final board. In the MDF industry, wood fiber quality has significant effect on final board properties and is evaluated based on visual and tactile inspections. The research hypothesis is that, during the refining, a variety of chemical and physical changes must occur that are not apparent in visual/tactile inspection. An industry/university cooperation, this work studies effects of refining energy (adjusted by refiner-plate gap) on fiber: size, porosity, surface area, surface and bulk chemistry, fiber crystallinity and rheology, and fiber interaction with adhesive. The intention is to reveal novel aspects of fiber quality that might impact MDF properties or process control efficiency, specific to a single industrial facility. It was found that refining had significant effect on wood fiber properties: increased surface area, porosity, and changed the surface energy; and also on wood fiber chemistry: significant degradation in wood fiber main chemical components: poly saccharides and lignin. These changes also had effect on fiber/adhesive interaction. Therefore the hypothesis was confirmed that MDF fiber quality must involve more than a simple visual/tactile evaluation and the effect of refining can be detected on other fiber quality aspects. However more research needs to be conducted to test and find feasible new methods for fiber quality evaluation.

Most galaxies are either actively forming stars or quenched, but there is a small number of galaxies in transition from one population to the other. These galaxies are "quenching" if they are in the process of becoming quenched or "rejuvenating" if they are returning to the star-forming main sequence after a period of being quenched. Quenching occurs when a galaxy’s limited cold gas supply is heated or removed, halting star formation, while rejuvenation refers to any process that reintroduces cold gas to quenched galaxies, reigniting star formation. Rejuvenating galaxies, which are significantly rarer and less well-studied than quenching galaxies, can offer valuable insights into galaxy evolution processes. This thesis investigates the properties of transitional galaxies, with a focus on their gas content, to explore the mechanisms driving quenching and rejuvenation. We employ a recent classification method using GALEX NUV and Sloan Digital Sky Survey H-alpha measurements to identify transitional galaxies and analyze the derived gas properties of those in the xGASS and xCOLD GASS surveys. We find that rejuvenating and quenching galaxies have intermediate gas fractions compared to actively star-forming and quenched galaxies, and that rejuvenating and quenching galaxies have similar depletion times to star-forming and quenched galaxies, respectively. We also find that the rejuvenating population, particularly at lower stellar mass, is efficient at converting its atomic gas supply to molecular hydrogen, which could be attributed to their high gas-phase metallicities at low stellar mass. / Thesis / Master of Science (MSc)

Title from accompanying document. / Digitized by Kansas Correctional Industries

This study aimed to examine and describe the perceptions of English-medium instruction of tertiary &ndash / level students in a private university in Turkey. The scale which consists of a demographic inventory, a questionnaire, and a semi-structured interview were used by the researcher. The results of the questionnaire were analyzed through SPSS 15.0. This data gathering instrument was implemented on 233 students studying at three different faculties at Atilim University which offer English-medium instruction. In analyzing the data, descriptive statistics as frequency, percent, and standard deviation and inferential statistics such as one sample t-test and Pearson Product Moment Correlations were used. As the second scale of the present study, semi-structured interviews were conducted with 10 students studying at three different faculties at Atilim University which offer English-medium instruction (EMI). The results of the interviews were analyzed through content analysis. The results of the study revealed that students support EMI at tertiary level and they hold positive attitudes towards EMI in terms of the improvement of language skills in English / nevertheless, they experience some difficulties in the learning of the content delivered in English. Results also showed that there is a positive relationship between students&rsquo / proficiency levels and perceptions towards EMI regarding the learning of the subject matters. Moreover, it was found that there is also a positive relationship between students&rsquo / attitudes towards EMI regarding the learning of the subject matters and their academic success.

Martin Streda is a one-act monodrama for baritone and an ensemble of eight instrumentalists. The libretto was written by the composer. The drama concerns Martin Streda, a Czech political prisoner in a solitary confinement cell of a communist concentration camp on the eve of his death. The opera has a duration of approximately 30 minutes and is divided into four main parts. The analytical essay describes the development and operation of Mar-sys, a collection of twenty pitch aggregates derived from intervalic cells, rhythmic cells drawn from the Morse code alphabet, and other pitch organization systems.

The objectives of this study were to investigate existing theory regarding the conceptual learning of young learners and to determine what core concepts Grade 5 learners need to learn. An empirical investigation as to whether these learners were familiar with the mother tongue words for the identified core concepts in syllabuses and textbooks, and to investigate whether they could recede these concepts into English (the medium of instruction in their classrooms) was also undertaken. The role of conceptual awareness in learning was discussed based on Piaget's, Vygotsky's and Clark's theory. They explain how concepts and knowledge are acquired and also how language affects this process. Learners are required to know the concepts of what they learn and should recede the information or concepts into the language used for a specific learning task. In the case of this study it was English. The study revealed that many learners who were investigated in this study did not possess the knowledge to encode many of the core or broader concepts in Tshivenda, their mother tongue. Learners also seemed to learn some concepts and the English encoding for them simultaneously. The findings showed, however, that most learners in Grade 5 could not recede many of the concepts that they possessed in L1 into English the Mol. It was clear that many learners in this study were not ready to switch from mother tongue instruction to English Mol in Grade 5. Their lack of conceptual awareness coupled with the lack of adequate English proficiency to learn the subjects in English may have been influenced by a number of possible reasons. Some reasons that were suggested were the following: a lack of prior knowledge of concepts that occur in Grade 5 syllabuses and textbooks; poorly trained teachers who are unable to assist learners to create links between existing knowledge and new knowledge; poor socio-economic circumstances and illiteracy and teachers who may lack English proficiency and cannot teach all subjects confidently in English. Some implications for the findings were suggested such as the following: if teachers are aware of the demands made on the conceptual framework of learners and the possible limitations that• they have regarding their conceptual readiness to learn, intervention is possible. Much can be done regarding the strategies that teachers may employ to enrich, expand, reconstruct, revisit or adapt concepts for learning. Such strategies include visual scaffolding, an enriched conceptual and language programme and a planned and structured approach to teaching language across the curriculum. / Thesis (M.A. (Applied Language and Literary Studies))--Potchefstroom University for Christian Higher Education, 2001

The objectives of this study were to investigate existing theory regarding the conceptual learning of young learners and to determine what core concepts Grade 5 learners need to learn. An empirical investigation as to whether these learners were familiar with the mother tongue words for the identified core concepts in syllabuses and textbooks, and to investigate whether they could recede these concepts into English (the medium of instruction in their classrooms) was also undertaken. The role of conceptual awareness in learning was discussed based on Piaget's, Vygotsky's and Clark's theory. They explain how concepts and knowledge are acquired and also how language affects this process. Learners are required to know the concepts of what they learn and should recede the information or concepts into the language used for a specific learning task. In the case of this study it was English. The study revealed that many learners who were investigated in this study did not possess the knowledge to encode many of the core or broader concepts in Tshivenda, their mother tongue. Learners also seemed to learn some concepts and the English encoding for them simultaneously. The findings showed, however, that most learners in Grade 5 could not recede many of the concepts that they possessed in L1 into English the Mol. It was clear that many learners in this study were not ready to switch from mother tongue instruction to English Mol in Grade 5. Their lack of conceptual awareness coupled with the lack of adequate English proficiency to learn the subjects in English may have been influenced by a number of possible reasons. Some reasons that were suggested were the following: a lack of prior knowledge of concepts that occur in Grade 5 syllabuses and textbooks; poorly trained teachers who are unable to assist learners to create links between existing knowledge and new knowledge; poor socio-economic circumstances and illiteracy and teachers who may lack English proficiency and cannot teach all subjects confidently in English. Some implications for the findings were suggested such as the following: if teachers are aware of the demands made on the conceptual framework of learners and the possible limitations that• they have regarding their conceptual readiness to learn, intervention is possible. Much can be done regarding the strategies that teachers may employ to enrich, expand, reconstruct, revisit or adapt concepts for learning. Such strategies include visual scaffolding, an enriched conceptual and language programme and a planned and structured approach to teaching language across the curriculum. / Thesis (M.A. (Applied Language and Literary Studies))--Potchefstroom University for Christian Higher Education, 2001

Lorsque la création d'une image se fait grâce à l'utilisation, la manipulation d'un appareil, il arrive un moment où celui-ci devient central et le sujet de tous les questionnements. La pratique de la photographie m'a amenée à ce type d'interrogation. Comment photographier devient soudain une question aussi récurrente qu'essentielle. Une réflexion critique sur ce que l’on croit être une simple technique et que l'on emploie pour faire une image photographique, libérée alors de toutes fascinations, devient possible. Mais comment procéder à l'analyse de l'appareillage photographique? C'est en considérant l'appareil comme un ensemble global, un paradigme, participant pleinement à la création et la conditionnant en même temps, qu’il paraît possible de mener une réflexion sur cette place particulière qu'occupe l'appareillage photographique dans la réalisation d'image ou (/ et) d'installation de celle-ci. Cette interrogation peut dès lors être étudiée à travers une mise à plat de l'appareil photographique dans une définition plus élargie de ce dernier que la simple considération de l’appareil de prise de vue afin de savoir ce qu’il est par nature mais aussi dans ses usages, et alors de découvrir sa poïétique propre ainsi qu’un rapport singulier au réel. Cette méthodologie s'apparente à une déconstruction, puis une monstration, voire une mise en excès pour eux-mêmes des éléments premiers et fondamentaux de l'appareil producteur d'image photographique (grain, brûlure, planéité, obscurité...) ; ce qui le constitue et en fait sa particularité. D'une autre manière, le conditionnement qu'opère l'appareillage photographique dans la réalisation d'images peut se penser par une mise en évidence du procès : une mise en valeur, une exhibition du processus du faire, de la démarche, de la méthode qui permet à l'image d'être. Cette démarche et cette recherche recontextualisent le faire, l'expérimentation, la poïétique à l'oeuvre dans chaque réalisation plastique d'image photographique. / When creating a picture is done by using and operating a camera there comes a time when this device becomes essential and a subject for all kinds of questioning. Photography brings this type of questioning to my mind. How to take a picture all of a sudden happens to be an essential as well as recurring question. Then a critical appreciation free from fascination may be undertaken on what we consider as a mere technique that is used to take a picture. But how to proceed to the analysis of the photographic medium ? Considering the medium as a global set a paradigm taking full part in the creation and conditioning it at the same time allows the carrying out of an appreciation on this particular part taken by the photographic medium in the realization (or installation) of a picture. From that moment this appreciation can be studied by examining all the elements of the camera in a wider definition of the latter than a mere consideration of the camera itself in order to know not only what it is but also how to use it and thus to find out its own “poïétique” as well as its unique connection to reality. This method relates to a deconstruction then a bringing forward of the primary and fundamental elements of a photographic medium (grain, burn, flatness, darkness…) ; what it is made of and makes it unique . In a different way, the conditioning that the photographic equipment operates in the realization of pictures can be considered as a disclosure of the process : an emphasis on the process, the approach, the method that allows the picture. This approach and this research make it possible to recontextualize the process the « poïétique » at work in each artistic creation of photographic pictures.

L'objectif de cette thèse est de proposer une modélisation du rayonnement thermique dans un réacteur nucléaire au cours d'un accident grave conduisant à la dégradation des crayons combustibles. Un réacteur étant refroidi par de l'eau, le rayonnement se fait en présence de vapeur et de gouttes d'eau. Le modèle de rayonnement est construit à partir d'expériences de dégradation de crayons fossiles, réalisées sur le réacteur expérimental PHEBUS.Les configurations géométriques accidentelles de grappes de 21 crayons dégradés ont pu être caractérisées en trois dimensions à partir d'images issues de tomographies. Les propriétés radiatives homogénéisées de ces configurations ont été complètement caractérisées à partir de la fonction de distribution cumulée d'extinction Gext et de la fonction de phase de diffusion p. Ces fonctions ont été précisément calculées par une méthode de Monte Carlo. Gext, qui n'est pas de type exponentiel, ne suit pas la loi de Beer. p dépend fortement des angles d'incidence et de diffusion. A partir de l'équation de transfert radiatif généralisée à des milieux non Beeriens, introduite par Taine et al., un tenseur des conductivités radiatives a été déterminé par une méthode de perturbations, en supposant dans une première étape la phase fluide transparente. Les conductivités radiatives axiales et radiales ont été exprimées avec précision en fonction de la porosité, de la surface spécifique et de l'absorptivité locale du milieu poreux. Dans une deuxième étape, une équation de transfert radiatif à trois températures a été établie. Dans ce modèle, les effets de la phase fluide sur le rayonnement ont été couplés aux effets des parois. Les propriétés radiatives de la vapeur et des gouttes d'eau sont calculées en utilisant respectivement le modèle CK et la théorie de Mie, dans les conditions thermohydrauliques typiques des accidents de réacteur. Les flux radiatifs s'expriment en fonction de flux conductifs couplés caractérisés par des conductivités radiatives associées aux champs de températures de chaque phase. Les puissances volumiques échangées par rayonnement entre les phases sont aussi calculées à partir de ce modèle. / This work aims at modelling thermal radiation in a nuclear reactor, in the course of a severe accident leading to its degradation. Because the reactor coolant is water, radiative heat transfer occurs in presence of steam and water droplets. The 3D geometry of a fuel bundle with 21 damaged rods has been characterized from tomography images. The degradation of the rods has been simulated in the experimental small-scale facility PHEBUS.The homogenized radiative properties of the considered configurations with a transparent fluid phase have been completely characterized by both the extinction cumulated distribution function Gext and the scattering phase functions p. Gext strongly differs from the exponential function associated with the Beer law and p strongly depends on both the incidence and the scattering directions. By using the radiative transfer equation generalized for non Beerian porous media by Taine et al. the radiative conductivity tensor has been first determined with a transparent fluid phase, by a numerical perturbation method. Only the diagonal radial and axial components of this tensor are not equal to zero. They have been fitted by a simple law only depending on the porosity, the specific area and the wall absorptivity. In a second step, a radiative transfer equation based on three temperatures is established. This model takes into account a semi transparent fluid phase by coupling the radiative properties of fluid and solid phases. The radiative properties of water steam and droplets are calculated respectively with the CK approach and Mie theory, in typical thermal hydraulics conditions of reactor accidents. The radiative fluxes verify the Fourier law and are characterized by radiative coupled conductivity tensors associated with the temperatures of each phase. The radiative powers exchanged between phases per unit volume are also calculated from this model.

This Master Thesis is focused on the topic of internationalization of small and medium-sized enterprises (SMEs). The main goal of this thesis was to find out if the czech SMEs are able to participate in international trade, how can they achieve that and if the provided support of SMEs is sufficient. The theoretical part describes the term small and medium-sized enterprises, its specifics, significance and the evolution of the SME sector in Czech Republic. The theoretical part further deals with particular aspects of internationalization and with the quality of the provided support of SMEs in Czech Republic. The practical part was realized in the form of semistructured interview with a owner of Simplejohn, inc and the main goal of it was to verify the conclusions reached in the theoretical part.