This paper presents the methods of predicting the steady-state two-phase flow (steam and water) pressure drop across the restrictions of annular geometries formed when tubes extend through circular holes in tube support plates. Two approaches are discussed and a detailed sample calculation of the one selected is presented. The major areas of discussion are the orientation of tubes-to-tube support plate holes, and the thickness of tube support plate. Finally, the conclusion gives a comparison of methods and recommendations for future investigations.

The flow patterns of an air-water mixture at atmospheric pressure were visually observed through a simulated vertical steam generator tube support plate of circular hole and trefoil designs. Flow oscillations with a period on the order of 0.4 seconds were observed in both support plates at similar mass flow rate combinations. The oscillation consisted of a period of rapid surging followed by a low flow or stagnation period on the order of 0.1 seconds. Reverse (downward) flow was also observed for part of the oscillation cycle in the trefoil support plate. The flow oscillations that exist in one tube support plate are coupled to the oscillation phase that exists in the preceding tube support plate. The operation of a steam generator in a region where this flow oscillation occurs could result in reduced to steam generator life due to increased corrosion.

This thesis is missing page vi and is not in any of the copies. -Digitization Centre / The specific heat of (Mg1-xMnx) 2P2O7 was measured in the vicinity of the alpha-beta phase transition for 0 < x < 0.04. The temperature and character of the phase transition were found to depend on the composition of the sample and the method of preparation. The results are discussed with relation to the crystal structures of Mg2P2O7 and Mn2P2O7 . / Thesis / Master of Science (MS)

The vapour-phase reaction of 2-methyl-tetrahydropyran and 2-ethyltetrahydropyran with aniline over an activated alumina catalyst has been studied. The product, in each case, consisted of a mixture of an N-arylpiperidine, an N-arylpyrrolidine formed by ring contraction, and two N-alkenylanilines formed by ring opening. The structures of the nitrogen heterocyclic compounds were established by independent syntheses involving the reaction of the appropriate dibroinoalkane with aniline. The N-alkenylanilines were characterised by hydrogenation to known N-alkylanilines and by identification of the osonolysis products. / Thesis / Master of Science (MS)

In this thesis, the design of a voltage-source inverter (VSI)-based three-phase impedance analyzer's perturbation injection unit (PIU) is described including all relevant power stage and control design. Both series and shunt injection are examined from .1 Hz to 1000Hz. Both types of injection are performed using only energy from the system under test stored in a DC link capacitor. Sinusoidal, square (pulse), and chirp perturbation waveforms are explored. Results from a constructed realization of the design are presented, and the limits of the device characterized. The maximum achievable perturbation power is 10 kW in shunt and 8 kW in series on a 460 V, 100 kW bus. Using the same conditions, maximum power is achievable from 10Hz to 100Hz, at .1Hz, .72 kW is achievable, and at 1000Hz, 6.0 kW is achievable. / Master of Science

International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / The architecture of the High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA’s Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an overview of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

No description available.

A new instrument, the liquid crystal point diffraction interferometer (LCPDI), has been developed for the measurement of phase objects. This instrument maintains the compact, robust design of Linnik's point diffiaction interferometer (PDI) and adds to it phase stepping capability for quantitative interferogram analysis. The result is a compact, simple to align, environmentally insensitive interferometer capable of accurately measuring optical wavefronts with very high data density and with automated data reduction. This dissertation describes the theory of both the PDI and liquid crystal phase control. The design considerations for the LCPDI are presented, including manufacturing considerations. The operation and performance of the LCPDI are discussed, including sections regarding alignment, calibration, and amplitude modulation effects. The LCPDI is then demonstrated using two phase objects: a defocus difference wavefront, and a temperature distribution across a heated chamber filled with silicone oil. The measured results are compared to theoretical or independently measured results and show excellent agreement. A computer simulation of the LCPDI was performed to verify the source of observed periodic phase measurement error. The error stems from intensity variations caused by dye molecules rotating within the liquid crystal layer. Methods are discussed for reducing this error. Algorithms are presented which reduce this error; they are also useful for any phase-stepping interferometer that has unwanted intensity fluctuations, such as those caused by unregulated lasers. It is expected that this instrument will have application in the fluid sciences as a diagnostic tool, particularly in space based applications where autonomy, robustness, and compactness are desirable qualities. It should also be useful for the testing of optical elements, provided a master is available for comparison.

Ce travail est effectué dans le cadre d'une thèse Conventions Industrielles de Formation par la Recherche (CIFRE) entre l’entreprise Sophia Antipolis Énergie Développement (SAED) à Valbonne et l'Institut Matériaux Microélectronique Nanosciences de Provence (IM2NP) – CNRS – Université du Sud Toulon-Var.L’objectif de cette collaboration est l’évaluation du potentiel technico-économique de divers matériaux pour le stockage de l’énergie thermique par chaleur latente, adapté aux niveaux de température des capteurs solaires développés par SAED. En effet, le stockage de l’énergie est un des principaux verrous technologiques reconnus pour les procédés ayant recours à des énergies renouvelables intermittentes et en particulier pour les centrales héliothermodynamiques.Après une introduction sur le potentiel et l’intérêt des centrales solaires thermodynamiques à basse température, un bref état de l’art des principaux types de stockage de l’énergie est présenté. Le deuxième chapitre aborde plus en détail le principe du stockage thermique par chaleur latente et recense une centaine de matériaux sélectionnés dans la littérature pour leur changement de phase dans la gamme de température 70 - 140°C. Les critères de sélection retenus y sont exposés.Des analyses thermiques par calorimétrie différentielle à balayage sont effectuées de façon systématique sur les différents Matériaux à Changement de Phase (MCP) sélectionnés. Les résultats de ces mesures, présentés dans le chapitre III, caractérisent avec précision le comportement de ces matériaux au chauffage. La transformation au refroidissement est étudiée au moyen d’un dispositif conçu spécifiquement pour représenter au mieux les conditions imposées dans une enceinte industrielle. Cette étude, présentée dans le chapitre IV, permet d’affiner la sélection des MCP pour ne garder que ceux dont la réversibilité du changement d’état est compatible avec une utilisation industrielle en tant que milieu de stockage de l’énergie thermique. Les chapitres V et VI permettent d’étudier plus en détails les spécificités de deux types de MCP que sont les polyols et les mélanges eutectiques de nitrates.Le dernier chapitre est consacré à la modélisation des échanges thermiques au sein d’une cuve de stockage contenant un MCP encapsulé. L’objectif est de disposer d’un outil de prédiction des performances d’une unité de stockage par chaleur latente, afin d’analyser l’influence des différentes solutions envisagées sur le productible d’une centrale thermodynamique solaire et leur impact sur le coût du kWh électrique produit. / This work of thesis is done within the framework of industrial agreements research training, between the company Sophia Antipolis Energie Développement (SAED) in Valbonne, and the Institut Matériaux Microélectronique Nanosciences de Provence (IM2NP) – CNRS – University Sud Toulon-Var.The aim of this collaboration is to investigate the technical and economic potential of various materials for thermal energy storage by latent heat, suitable for temperature levels of the solar collectors developed by SAED. Indeed, energy storage is a major technological barrier to the process resorting to intermittent renewable energies and especially for thermodynamic solar power plants.After an introduction on the potential and interest of solar power plants working at low temperature, a brief state of art of the main types of energy storage is presented. The second chapter addresses in detail the principle of thermal storage by latent heat and identifies a hundred of selected materials from the literature for phase change in the temperature range 343 - 413 K. The selection criteria are exposed.Thermal analyses by differential scanning calorimetry are carried out systematically on the various selected Phase Change Materials (PCMs). The results of these measurements, presented in chapter III, accurately characterize the material behavior when heated. The transformation on cooling is studied using a device specifically designed in order to be more representative of conditions found in an industrial enclosure. This study, presented in chapter IV, allows refining the selection of PCMs retaining only those whose phase change reversibility is compatible with an industrial use as medium for thermal energy storage. Chapters V and VI are used to study in further detail the specifics of two types of MCP, respectively polyols and eutectic mixtures of nitrates.Final chapter deals with the modeling of heat transfer into a storage tank containing encapsulated PCM. The aim is to provide a tool for predicting the performance of a latent heat storage unit, in order to analyze the influence of different options on the solar power plant energy yield and their impact on the kWh cost.

Ces dernières années, la physique de la matière condensée a connu une profonde révolution de concepts par la découverte de nombreuses phases de la matière qui ne sont pas classifiables à la Landau, c’est à dire par leur groupe de symétrie. Si les premiers travaux remontent à ceux des effets Hall quantiques (entier et fractionnaire), ce n’est que récemment, avec l’avènement du graphène et des isolants topologiques que les physiciens ont réalisé que ces phases de la matière ne nécessitent, dans l’absolu, ni champ magnétique, ni basse température, par opposition aux effets Hall quantiques précédemment cités. Ces nouveaux états de la matière sont caractérisés non pas par la géométrie du problème mais plutôt par la topologie. Ici donc, la forme précise du spectre électronique n’est pas importante, seules certaines caractéristiques, comme la présence ou l’absence d’un gap, le sont. De manière similaire à la classification de Landau des groupes de symétries, il est possible de classifier ces nouveaux systèmes par l’intermédiaire de groupes topologiques. La branche mathématique invoquée est celle de la topologie algébrique. A travers les invariants qu’elle génère, il est possible de classer les états topologiquement non-triviaux. De plus, les transitions entre des états à topologies distinctes sont aussi accessibles par cette théorie. Les travaux réalisés dans le cadre de cette thèse s’intéressent aux effets topologiques dans la structure de bandes de matériaux bi-dimensionnels. Après une présentation du formalisme mathématique général, un premier chapitre s’intéressera à la topologie locale, c’est à dire pour une portion restreinte de la première zone de Brillouin, des points de croisements de bandes, dits points de Dirac. Un effort sera porté vers la classification de ces systèmes et des transitions associées. Le chapitre suivant mettra en lumière un moyen efficace de mesurer les effets de la topologie des électrons en deux dimensions. Il s’agit de l’étude des niveaux de Landau qui résultent de l’application d’un champ magnétique 5transverse au plan des électrons. Les points de Dirac se transmutent alors en niveaux à énergie nulle topologiquement stables, c’est à dire peu ou pas influencés par les diverses perturbations. L’étude des différents modèles justifiera la discrimination entre la physique à champ magnétique faible et celle à champ magnétique fort, faible ou fort étant très dépendant du système étudié. Enfin, dans un dernier chapitre plus prospectif on s’intéressera à la topologie globale, c’est à dire pour l’ensemble de la première zone de Brillouin. Ce type d’étude est surtout caractérisé par l’existence d’états de bords robustes. On en fera l’expérience d’une double manière. D’abord par l’étude un modèle à un électron, puis par celle d’un système en forte interaction de N électrons. A travers les différents exemples étudiés, on s’attachera à démontrer la puissance de l’outil topologique pour les problèmes de la matière condensée, phénomène qui devrait s’accentuer les prochaines années. / During the last few decades, condensed matter physics has witnessed a deep refoundation of its paradigms, through the discovery of many systems that the usual symmety classification à la Landau cannot handle properly. Although the first major breaktroughs were realized at the time of discovery of integer and fractional quantum Hall effects, only recently physicists have agreed that these peculiar phases of matter require neither a magnetic field nor low temperature. Those new states of matter cannot be caracterized by the geometric aspects of the model but rather by topological ones. The precise shape of the electronic spectrum is no longer relevant, but only particular features are, such as the presence or the absence of a gap. Similarly to the Landau classification scheme, one can achieve a construction through extensive use of topological groups. This is the realm of algebraic topology. Related generated topological invariants can hold a classification of non-trivial topological states, as well as of the accompanying transitions. This thesis focusses on peculiar topological features of two-dimesnsional electronic band structures. After a technical introduction to the underlying formalism, the first chapter is devoted to local topology, that is for a restricted piece of the first Brillouin zone, of band crossing points, also known as Dirac points. Special care is taken to classify these points and related transitions. The next chapter sheds some light on a particularly efficent way of measuring topology for two-dimensional electrons. This is achieved through measurements of Landau levels that are generated by a magnetic field applied perpendicular to a plane. Dirac points then generate zero Landau levels that are topologically stable, i.e. almost not influenced by perturbations at all. Distinctions between low and high magnetic fields will prove to be relevant, although very system-dependant. Through the several models studied, we particularly stress out the importance of the topological tool for condensed matter physics, past present... and future.