Dissertations / Theses on the topic 'Physics Hydrostatics'

This thesis describes an experimental investigation of the photoluminescence emissions from firstly, bulk In0.53 Ga0.47 As and secondly, InGaAs\InP and AlAs\GaAs quantum well structures, as a function of hydrostatic pressure. Two high pressure systems have been developed and successfully used in the course of this work, an 8kbar piston and cylinder system and a miniature diamond anvil cell. From the high pressure measurements on the bulk InGaAs, both at room anti liquid nitrogen temperatures, it is shown that the pressure dependence of the direct band-edge luminescence is non-linear and independent of temperature. Using an empirical equation of state and making some assumptions as to the value of the bulk modulus, it is found that the band-edge luminescence is linearly dependent upon the lattice constant and may be described by a band-edge deformation potential of -8.25 +/- 0.1eV. Theory compares favourably with this value. From low temperature measurements of both quantum well systems it has been possible to deduce a quantitative description of how the conduction and valence band-edge discontinuities vary as a function of the applied pressure. It is shown that the band-offset ratio changes with pressure. This work constitutes the first observation of this phenomenon which had previously been thought either too small to be of consequence, or simply ignored. It is found that the conduction-band discontinuity in InGaAs\InP quantum wells decreases at -2.3 +/- 0.6meV/kbar while its valence-band discontinuity remains constant. The valence-band discontinuity in the AlAs\GaAs superlattice is directly measured to increase at +1.1 +/- 0. ImeV/kbar. An analysis of reported data for A1 Ga As/GaAs quantum wells shows that the pressure coefficient of the X l-x valence-band discontinuity is linearly dependent upon the alloy composition x. Theories of band-offset ratios and in particular the "model-solid" theory of Van de Walle and Martin (Van de Walle 1987), agree exceedingly well with these experimental findings. It is suggested that such agreement lends weight to the assumption that heterojunction band-edge discontinuities are intrinsic to the bulk properties of the host materials.

Thesis (Ph.D.)--University of Missouri-Columbia, 2006.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (February 28, 2007) Vita. Includes bibliographical references.

The research for this thesis led to the development of two environmental detectors, whose function was to identify predetermined threshold levels of the analyte. The research centred onto two types of analyte; immiscible and dissolved, both occurring in water based locations. The first detector was developed to detect the accumulation of oil within an oil/water interceptor. Pollution from oil spillages is a major contaminate of water systems and the control of this potentially hazardous material has legal obligations. This liquid, which naturally separates from water, accumulates within the interceptor enclosure and can be removed once the quantity of oil reaches the desired level. However, the often unpredictable nature of oil leaks and spillages means that the accumulation of oil within an interceptor is an irregular occurrence. Interceptor detectors based upon electrical techniques already exist. This research specifically developed a detection system that operated without any electrical devices within the interceptor. The research explored several possible avenues, eventually pursuing a technique based upon pressure change, based on the density differential between water and oil. The final system was capable of identifying when the oil had reached a depth of 200 to 250 mm within the interceptor. The second detection system, a portable microfluidic fluorimeter, was intended for placement in locations for the direct analysis of water. Glutathione was chosen as a model analyte, associated with a sex pheromone and prior to the onset of spawning may be found in high concentrations. The system that has been developed is capable of selectively sensing glutathione to below 10 μM. However, the threshold concentration in the proximity of its release as a pheromone is greater than 100 μM and within this range the fluorimeter produced a linear response. The fluorimeter used an LED light source with a PMT detector. An analysis could be made every seven minutes, using 150 μL each of analyte and reagent for every cycle. Through assessment of a pre-made standard, the viability of the microfluidic system could be assured with regards to blockages or other malfunctions of the system.

This work proposes a Teaching Unit following the principles of the Potentially Meaningful Teaching Units (PMTU) proposed by Moreira (2011), having as a guiding axis the teaching of density and pressure content. The theoretical reference used is that of Significant Learning Theory. The data collected from the application of the PMTU in the classroom will be treated in a qualitative approach based on the case study analysis of the proposed activity in its context, in order to determine or test the elements that define a potentially significant material in a first year of high school. An initial questionnaire will be carried out initially to identify the students' previous knowledge. Next, the preparation and implementation of the PMTU in the classroom will be carried out and finally, a final questionnaire will be applied to verify signs of significant learning and conceptual evolution of the students. It is expected, from the implementation of the PMTU, to identify evidence of significant student learning throughout the teaching and learning process.
Esse trabalho propõe uma unidade de ensino seguindo os princípios da Unidade de Ensino Potencialmente Significativa (UEPS) proposta por Moreira (2011), tendo como eixo norteador o ensino dos conteúdos densidade e pressão. O referencial teórico utilizado é o da Teoria da Aprendizagem Significativa. Os dados coletados a partir da aplicação da UEPS em sala de aula serão tratados numa abordagem qualitativa a partir da análise de estudo de caso da atividade proposta em seu contexto, de forma a determinar ou testar os elementos que definem um material potencialmente significativo, em uma turma de primeiro ano do ensino médio. Será realizado inicialmente um questionário inicial para identificação dos conhecimentos prévios dos estudantes. Em seguida, será realizado a elaboração e aplicação da UEPS em sala de aula e por último, será aplicado um questionário final para verificar indícios de aprendizagem significativa e evolução conceitual dos estudantes. Espera-se, a partir da aplicação da UEPS, identificar indícios de aprendizagem significativa dos estudantes durante todo o processo de ensino e aprendizagem.
São Cristóvão, SE

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This work presents a study on the teaching and learning of concepts related to the hydrostatic principles for basic education in a meaningful learning perspective, according to a pedagogical approach based on the history of science as a means of contextualization and in experimental practices in an investigative approach for knowledge constructing. Participants are twenty one students from the second grade of a public high school. This study aims to evaluate limits and possibilities for the learning and the teaching practice of these contents in an investigative approach based on experimentation and the history of science. The instruments of data collection are observation, focus group, protocols of activities and open questionnaire. The conclusion obtained suggests that the teaching methodology adopted was considered innovative and promoting of learning due to interest, dialogue and argumentation in the classroom, helping to make the student an active actor in the process of learning, in addition to making this process enjoyable for both students and for the teacher. However, the teaching methodology used in this study did not include the participation of students in the planning and execution of experiments, according to the participants themselves, which points to future directions of teaching practices which consider in planning teaching some assignments for students as autonomy and responsibility with their own learning.
Este trabalho apresenta um estudo sobre o ensino e a aprendizagem de conceitos relacionados aos princípios da hidrostática para a educação básica na perspectiva de aprendizagem significativa, segundo uma abordagem pedagógica baseada na história da ciência, como forma de contextualização, e em práticas experimentais investigativas para a construção de conhecimentos. Os participantes são vinte e um estudantes da segunda série do ensino médio de uma escola pública. Este estudo tem como objetivo conhecer limites e possibilidades para a aprendizagem e a prática docente desses conteúdos em uma abordagem investigativa baseada na experimentação e na história da ciência. Os instrumentos de coleta de dados são observação direta, grupo focal, fichas de acompanhamento e questionário aberto. A conclusão obtida aponta que a metodologia de ensino adotada foi considerada inovadora e facilitadora da aprendizagem, por promover o diálogo, o interesse e a argumentação em sala de aula, auxiliando a tornar o estudante um ator ativo no processo de aprendizagem, além de tornar este processo agradável para os estudantes e para o professor. No entanto, a metodologia de ensino utilizada neste estudo não incluiu a participação dos estudantes no planejamento e execução dos experimentos, de acordo com os próprios participantes, o que aponta para direções de futuras práticas pedagógicas as quais consideram no planejamento didático algumas atribuições para os estudantes como a autonomia e responsabilidade com sua própria aprendizagem.

Verankerte Polymere können die Funktionalität einer Oberfläche beeinflussen. Der Schwerpunkt dieser Arbeit liegt auf der Untersuchung von Polymerbürsten aus Polyacrylsäure (PAA) und Poly(N,N-dimethylaminoethyl methacrylat) (PDMAEMA). Auf Oberflächen, die mit PAA Bürsten beschichtet sind, können Proteine im nativen Zustand immobilisiert werden. Für PDMAEMA ist eine Reaktion auf externe Reize bekannt. So kann dessen untere kritische Lösungstemperatur (LCST) zur Einstellung der Hydrophobizität von Oberflächen verwendet werden. Erstmalig im Rahmen dieser Arbeit wurde untersucht, wie sich hydrostatischer Druck von bis zu 1000 bar auf die Funktionalität der verwendeten Polymerbürsten auswirkt. Aus Diblock-Kopolymeren wurden Langmuir-Filme unterschiedlicher Ankerdichte mit der Langmuir-Schäfer Technik auf feste Substrate übertragen. Die Funktionalität der PAA Bürsten wurde vor und nach der Adsorption von Rinderserumalbumin (BSA) in gepufferter D2O-Lösung mit Hilfe der Neutronenreflektometrie (NR) bei 1 bar und 900 bar an der fest-flüssig Grenzfläche untersucht. Es wurden Volumenfraktionsprofile der PAA Bürste und adsorbierten BSA extrahiert, woraus sich eine lineare Abhängigkeit zwischen Ankerdichte und Menge an adsorbiertem Protein feststellen ließ. Erhöhung des hydrostatischen Druckes auf 900 bar veränderte weder die PAA Volumenprofile noch die Immobilisierung von BSA. Die PDMAEMA Bürsten wurden mittels NR bei Temperaturen von 20-60 °C und Drücken von 1-1000 bar untersucht. Zur Analyse der Daten wurde ein neuartiges Dichteprofil-Modell verwendet. Temperaturerhöhung führt zur stetigen Abnahme der Bürstendicke. Dies lässt sich durch den LCST induzierten Phasenübergang der Polymere vom hydrophilen in einen hydrophoben Zustand erklären. Es wurde gefunden, dass eine Erhöhung des hydrostatischen Druckes diesem Prozess entgegenwirkt. Strukturänderungen der Polymerbürsten bei Erhöhung der Temperatur um 10 K ließen sich durch Erhöhung des Druckes um 1000 bar rückgängig machen.
The functionality of an interface can be modified by polymer brushes. The focus of this work is on brushes of either polyacrylic acid (PAA) or poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). PAA brushes provide a soft interface that prevents the denaturation of adsorbed proteins. PDMAEMA is known to respond to external stimuli. The lower critical solution temperature (LCST) of PDMAEMA can be used to tune the hydrophobicity of the interface with temperature. For the first time, the effect of elevated hydrostatic pressure, up to 1000 bar, on the functionality of these systems is investigated. Planar PAA and PDMAEMA brushes are prepared from precursor diblock copolymer Langmuir layers with varied grafting density utilizing the Langmuir-Schäfer transfer technique. For solvent-swollen PAA brushes, neutron reflectivity (NR) measurements are conducted at the solid-liquid interface after incubation in buffered D2O and after the adsorption of bovine serum albumin (BSA) from the aqueous liquid phase at 1 bar and 900 bar. Detailed volume fraction profiles of the PAA brush and adsorbed BSA proteins are extracted. The amount of adsorbed BSA is found to scale linearly with grafting density. An elevated hydrostatic pressure of 900 bar is found to have no impact on the structure of the PAA brush and its capability to bind BSA proteins. The PDMAEMA brushes are investigated by NR at the solid-liquid interface in a temperature range of 20 to 60 °C for hydrostatic pressures from 1 to 1000 bar. A novel theoretical model of the brush density profile is used to fit the experimental NR data. Increasing the temperature causes a continuous decrease of the polymer brush thickness due to a hydrophobic coil to globule transition of the polymer chains when crossing the LCST. Hydrostatic pressure is found to act antagonistic to temperature. The hydrophobic collapse of the PDMAEMA brush caused by a temperature increase of 10 K is counterbalanced by a pressure increase of 1000 bar.

Le retrait de la pâte de ciment est souvent à l'origine de nombreuses fissurations observées dans les structures en béton. Dans le cadre de cette étude nous nous sommes intéressés uniquement à l'étude du retrait endogène aux jeunes âges, ses effets sur la microstructure, les paramètres qui influencent sa cinétique, l'amplitude et l'origine de ce type de retrait. Le retrait endogène, conséquence de la contraction "Le Chatelier", est un phénomène bien connu de l'industrie cimentière. Dans les bétons confectionnés avec un rapport E/C de l'ordre de 0. 5, les effets de ce retrait sont inexistants. Le développement et l'utilisation de plus en plus fréquente des bétons à hautes et à très hautes performances posent de nouveaux problèmes sur l'apparition et la mesure du retrait endogène. Dans les premier et second chapitres, nous avons examiné la littérature concernant la structuration de la pâte de ciment à différentes étapes, les mécanismes d'hydratation, les différents types de retraits, les techniques de mesure associées et les facteurs qui influencent ce dernier. Dans le troisième chapitre, nous avons présenté une méthode que nous avons mise au point. Elle permet de mesurer les variations volumiques dès la fin du gâchage et sur une période de temps allant jusqu'à trois jours. Dans ce mémoire, nous présentons les résultats obtenus à partir d'une formulation de mortier à ultra hautes performances (UHP) et des résultats obtenus à partir de pâtes de ciment et de mortiers. Dans le quatrième chapitre, des analyses microstructurales, chimiques, minéralogiques, et physiques sont également présentées. Elles permettent de donner quelques indices sur l'origine du retrait endogène. Parallèlement nous avons présenté des résultats obtenus sur l'effet d'ajout de C3A dans un clinker, l'effet de la finesse Blaine et finalement les résultats de l'étude comparative entre différentes catégories de ciment.

SILVA, José Gláucio da. Propriedades Vibracionais do Dipeptídeo L-Alanil-Alanina submetido a deformações homogêneas. 2015. 131 f. Tese (Doutorado em Física) - Programa de Pós-Graduação em Física, Departamento de Física, Centro de Ciências, Universidade Federal do Ceará, Fortaleza, 2015.
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The dipeptide L-Alanyl – L-Alanine crystal was studied through polarized Raman scattering submitted to homogeneous deformations. The crystals were grown by slow evaporation technique from an aqueous supersaturated solution of the crystal powder. Rays-x diffractions measurements were realized to confirm a crystalline structure of the crystal. Polarized Raman scattering measurements were performed at room temperature, as well as the analysis of the group theory to the C4 factor group and a tentative assignment of the vibrational modes of crystal. Raman scattering measurements in the crystals as a function of temperature were realized between two intervals of temperature: first, at low temperature between 300 K and 11 K e 11 K and 300 K, and second, at high temperature between 300 K e 520 K and 520 K e 300 K, in the spectral range of 50 cm-1 to 3400 cm-1. From the results of low temperature measurements, it was possible to conclude that the crystal undergoes a second-order phase transition between 80 K and 60 K, from a tetragonal structure with C4 factor group to a monoclinic structure with C2 factor group, maintaining the same number of the molecules per primitive cell. The suggested mechanism to explain the phase transition is the occupation of non-equivalent sites by CH3 molecular groups present at Ala-Ala molecule. On the other hand, the crystal remained stable in the high temperature range studied, and the changes observed in the Raman spectra showed no evidence that the Ala-Ala crystal undergone phase transition or changes in molecule conformation. In those experiments were observed only quantitative changes in frequency and widths of the Raman modes, which are normal for any material subjected to variations in temperatures around 220 K. Raman scattering measurements in the crystals as a function of pressure in the pressure range between 0,1 GPa and 6,3 GPa, in compression and of 6,3 GPa and 0,1 GPa, in decompression, in the spectral region between 100 cm-1 and 3400 cm-1 showed two ranges where several qualitative changes occurred; the first, in low pressure interval between 1.7 GPa and 2.3 GPa and the second, at high pressure interval, between 4.5 GPa and 4.9 GPa. Between 1.7 GPa and 2.3 GPa, it was observed qualitative changes as well as the disappearance of an external mode around of 130 cm-1 and the anomalous behavior of other external mode around of 110 cm-1 for pressures of the order of 1,7 GPa. These qualitative changes suggest that the crystal exhibits a second order structural phase transition. Qualitative changes also were observed in others regions of the Raman spectrum through of special reorientation of the molecular groups CO2, CH3 and NH3. These qualitative changes characterize a structural second order phase transition. The mains qualitative changes observed between 4,5 GPa and 5,2 GPa were the disappearance of the external modes and the an large increasing of the width of the Raman modes, suggesting that the crystal exhibits a structural disorder in the crystalline structure when undergoes a phase transition for high pressures, possibly a amorphization. When performing decompression of the sample, the Raman spectrum returns to its initial form relative to pressure of 0,1 GPa indicating reversibility of phase transitions.
O cristal dipeptídeo L-Alanil-L-alanina (Ala-Ala) foi estudado através da técnica de espalhamento Raman polarizado submetido a deformações homogêneas. Os cristais foram crescidos pela técnica de evaporação lenta a partir de uma solução aquosa supersaturada do pó do cristal. Medidas de raios-x foram realizadas para confirmar a estrutura cristalina do cristal. Foram realizadas medidas de espalhamento Raman polarizado a temperatura ambiente, bem como análise da teoria de grupos para o grupo fator C4 juntamente com uma classificação exploratória dos modos normais de vibração do cristal. As medidas de espalhamento Raman foram realizadas em baixas temperaturas, entre 300 K e 11 K e 11 K e 300 K, e altas temperaturas, entre 300 K e 520 K e 520 K e 300 K, na região espectral de 50 a 3300 cm-1. Da análise dos resultados das medidas de baixas temperaturas foi possível concluir que o cristal exibe uma transição de fase de segunda ordem, entre 80 e 60 K, passando continuamente da estrutura tetragonal com grupo fator C4 para uma estrutura monoclínica com grupo fator C2 mantendo o mesmo número de moléculas na célula primitiva. O mecanismo proposto para explicar a transição de fase é a ocupação de sítios de simetria C1 não equivalentes pelos íons moleculares CH3 numa estrutura monoclínica pertencente ao grupo fator C2. O cristal manteve-se estável em todo o intervalo de alta temperatura estudado. Nestas experiências foram observadas apenas mudanças quantitativas nas frequências e larguras de linha dos modos Raman estudados, que é normal para qualquer material submetido a variações de temperaturas da ordem de 220 K. Medidas de espalhamento polarizado no cristal de Ala – Ala no intervalo de pressão entre 0,1 GPa e 6,3 GPa, na compressão, e de 6,3 GPa e 0,1 GPa, na descompressão, na região espectral de 100 cm-1 a 3400 cm-1 mostraram dois intervalos de pressão em que ocorrem diversas mudanças qualitativas; o primeiro entre 1,7 GPa e 2,3 GPa e o segundo entre 4,5 GPa e 4,9 GPa. Entre 1,7 GPa e 2,3 GPa foram observadas mudanças qualitativas significantes na região dos modos externos, tais como, o desaparecimento de um modo da rede em torno de 130 cm-1 e o comportamento anômalo de outro modo da rede em torno de 110 cm-1 para pressão de 1,7 GPa. Estas mudanças qualitativas sugerem que o cristal exibe uma transição de fase estrutural de segunda ordem. As outras regiões do espectro Raman do cristal apresentaram diversas mudanças qualitativas continuas no comportamento dos modos Raman das unidades que participam diretamente das pontes de hidrogênio, indicando que o cristal apresenta reorientações espaciais dos grupos moleculares CO2, CH3 e NH3. Estas mudanças qualitativas caracterizam uma transição de fase estrutural de segunda ordem. As principais mudanças qualitativas observadas entre 4,5 GPa e 5,2 GPa são o desaparecimento dos modos externos e, quantitativamente, um grande aumento na largura de linha dos modos Raman indicando que o cristal exibe uma desordem na estrutura cristalina durante a transição de fase de altas pressões, possivelmente uma amorfização. Na descompressão da amostra os espectros Raman são quase que totalmente recuperados na sua forma inicial indicando que o cristal apresenta transições de fase reversíveis.

Les régions d'interface du Soleil de la photosphère à la chromosphère et au delà de la basse couronne ont été étudiées depuis longtemps à partir des spectres éclairs obtenus durant les éclipses totales de Soleil. Les éclipses sont les plus adaptées à ce type d'observation, car l'occultation a lieu en dehors de l'atmosphère terrestre et sont exemptes de lumière parasite provenant du " disque occulteur " (c'est-à-dire la Lune), une propriété de grande importance lorsqu'on observe très près du limbe. La résolution temporelle des premiers spectres éclairs ne permettait pas de résoudre les basses couches de la région de transition et étaient dégradés par des effets non-linéaires qui affectaient les films photographiques. Les images Extrême-UV des régions du limbe obtenues récemment dans l'espace sont analysées avec des modèles hydrostatiques à une dimension, comme les modèles VAL, mais cette méthode ne tient pas compte du phénomène d'émergence du champ magnétique, associé au réseau chromosphérique qui est responsable de: i) les spicules et le milieu interspiculaire, ii) les jets coronaux et macrospicules, et iii) l'ovalisation de la chromosphère. Les composants de la région d'interface sont dynamiques et différents types d'ondes et de reconnexions magnétiques sont supposées agir. Un saut de température de 0.01 à 1 MK est observé autour de 2 Mm d'altitude plus loin, et produit plus loin le flot du vent solaire permanent. Le processus de chauffage responsable du saut de température et la source du vent solaire ne sont pas encore compris. Dans cette thèse, nous traitons ces problèmes à partir de spectres éclairs récents réalisés avec les technologies actuelles de détecteurs CCD rapides, images d'éclipse en lumière blanche et des images EUV obtenues avec des instruments de missions spatiales. Nous illustrons les mécanismes des émissions des raies à faible potentiel de première ionisation (FIP) présents dans les basses couches de l'atmosphère solaire. Nous identifions plus précisément les raies associées aux éléments low FIP à la fois à l'intérieur et en dehors des protubérances. Nous caractérisons en détail les enveloppes d'hélium dans les interfaces. Méthodes: 1) technique des spectres éclairs sans fente avec imagerie CCD rapide (éclipses 2006, 2008, 2009, 2010 et 2012). 2) Analyses des spectres du continu entre la myriade de raies d'émission au delà du limbe solaire et construction de courbes de lumière de quelques raies d'émission low FIP et high FIP. 3) Evaluations d'inversions d'intégrales d'Abel pour déduire des échelles de hauteurs et discussion de variations de température et de densité. 4) Analyse d'images EUV obtenues aux mêmes instants depuis AIA/SDO, SWAP, SOT/Hinode des missions spatiales, images en lumière blanche pour discuter des constituants de la couronne. Principaux résultats: i) Le bord du Soleil et la bifurcation de température : le vrai continu à partir du spectre observé aux altitudes de 400 à 600 km au dessus du limbe dans le contexte de de mesures de diamètre solaire et processus d'émission. ii) raies d'émission visibles dans les régions d'interface comprenant les raies He I et surtout la raie He II Pα visible à partir de 800 km au dessus du limbe, produite par photo-ionisation, montrant des enveloppes autour du Soleil et permettant le sondage de l'interface protubérance-couronne. iii) La contribution de structures de petite taille comme les spicules et macrospicules commençant à 1 Mm au dessus du limbe et montrant que les modèles hydrostatiques stratifiés 1D ne sont pas adaptés pour les couches supérieures. Nous montrons que les raies low FIP sont sur-abondantes dans l'interface photosphère-chromosphère, que la couronne solaire est alimentée en permanence par ces éléments. Le titane est un élément abondant dans le milieu interspiculaire, et une analogie sur les gradients de température entre les interfaces photosphère-chromosphère et protubérance-couronne peut être établie.

碩士
國立清華大學
動力機械工程學系
105
A cyber physical system (CPS) is an integration of computers and physical systems. In a CPS, the physical system is integrated with sensing, communication, and computing components. This research aims at constructing a framework for the cyber physical system, including a virtual system as well as a physical system. To demonstrate the capability of the constructed cyber physical system, we designed an experiment platform of a hydrostatic linear stage as the real physical system. Within the virtual system, we constructed the simulation model for each component, which was able to characterize the feature of the physical system. To reduce the complexity, the system model of each component was categorized into four major properties: static, dynamic, tolerancing design, and sensing & controlling. Then, we established the corresponding module to describe each property. The static module included properties, for example, the geometries, materials and loading parameters, while the dynamic module stated the derived dynamic performance of the corresponding static properties. The tolerancing module predicted the final performance after considering manufacturing uncertainty. The sensors, actuators, and controller were included in the fourth module to communicate between the virtual and physical systems. Using the CPS, we predicted the performance of the linear stage while designing, controlling, and maintaining the physical system after manufacturing. We will closely look into the extensibility of the framework; other advanced options may be added in the future.