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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Reflex?es quanto ? import?ncia das Constru??es Geom?tricas no ensino da Geometria Plana / Reflections about the importance of Geometric Constructions in teaching Plane Geometry

SALGADO, Jacymar de Almeida 16 August 2013 (has links)
Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2017-08-04T19:01:18Z No. of bitstreams: 1 2013 - Jacymar de Almeida Salgado.pdf: 1091711 bytes, checksum: f0ed1cc320f0c803135d5f30b832917e (MD5) / Made available in DSpace on 2017-08-04T19:01:18Z (GMT). No. of bitstreams: 1 2013 - Jacymar de Almeida Salgado.pdf: 1091711 bytes, checksum: f0ed1cc320f0c803135d5f30b832917e (MD5) Previous issue date: 2013-08-16 / The present work was carried out in three stages, which are the theoretical, research with professionals of education (mathematics teachers from public schools in the metropolitan region of Rio de Janeiro) and performing diagnostic and educational activities at the Municipal School Cruzeiro do Sul, Mesquita, Rio de Janeiro, with students from the 6th grade of elementary school. The work has shown promise in identifying a strong tendency of mathematics teachers in this region promote their practice in teaching Plane Geometry, highly influenced by a process algebrization this science and its teaching. This study aimed to promote reflection on the current teaching of Plane Geometry in elementary school in the metropolitan area of Rio de Janeiro, as well as provide a strong tool to minimize disability in its teaching. It is speculated, with strong evidence, that the abandonment occurred in Brazil, particularly in the region where the study was promoted, the use of Geometric Constructions in teaching plane geometry is, perhaps, the main factor that affects the teaching and learning of this discipline. / O presente trabalho foi realizado em tr?s etapas, que s?o parte te?rica, pesquisa com profissionais de educa??o (professores de matem?tica da rede p?blica da regi?o metropolitana do Rio de Janeiro) e realiza??o de atividades diagn?sticas e pedag?gicas na Escola Municipal Cruzeiro do Sul, Mesquita, Rio de Janeiro, com alunos do 6? ano do ensino fundamental. O trabalho mostrou-se promissor ao identificar uma forte tend?ncia dos professores de Matem?tica dessa regi?o em promoverem sua pr?tica pedag?gica, no ensino da Geometria Plana, altamente influenciados por um processo de algebriza??o desta ci?ncia e do seu ensino. Este trabalho teve como objetivo promover reflex?es sobre o atual ensino da Geometria Plana no ensino fundamental da regi?o metropolitana do Rio de Janeiro, bem como apresentar uma forte ferramenta para minimizar a defici?ncia no ensino da mesma. Especula-se, com forte ind?cio, que o abandono ocorrido no Brasil, em particular da regi?o no qual o estudo foi promovido, do uso das Constru??es Geom?tricas no ensino da Geometria Plana ?, talvez, o principal fator que afeta o ensino e aprendizagem desta disciplina.
322

The Development of Unique Focal Planes for High-Resolution Suborbital and Ground-Based Exploration

January 2019 (has links)
abstract: The development of new Ultra-Violet/Visible/IR range (UV/Vis/IR) astronomical instrumentation that use novel approaches for imaging and increase the accessibility of observing time for more research groups is essential for rapid innovation within the community. Unique focal planes that are rapid-prototyped, low cost, and provide high resolution are key. In this dissertation the emergent designs of three unique focal planes are discussed. These focal planes were each designed for a different astronomical platform: suborbital balloon, suborbital rocket, and ground-based observatory. The balloon-based payload is a hexapod-actuated focal plane that uses tip-tilt motion to increase angular resolution through the removal of jitter – known as the HExapod Resolution-Enhancement SYstem (HERESY), the suborbital rocket imaging payload is a Jet Propulsion Laboratory (JPL) delta-doped charge-coupled device (CCD) packaged to survive the rigors of launch and image far-ultra-violet (FUV) spectra, and the ground-based observatory payload is a star centroid tracking modification to the balloon version of HERESY for the tip-tilt correction of atmospheric turbulence. The design, construction, verification, and validation of each focal plane payload is discussed in detail. For HERESY’s balloon implementation, pointing error data from the Stratospheric Terahertz Observatory (STO) Antarctic balloon mission was used to form an experimental lab test setup to demonstrate the hexapod can eliminate jitter in flight-like conditions. For the suborbital rocket focal plane, a harsh set of unit-level tests to ensure the payload could survive launch and space conditions, as well as the characterization and optimization of the JPL detector, are detailed. Finally, a modification of co-mounting a fast-read detector to the HERESY focal plane, for use on ground-based observatories, intended to reduce atmospherically induced tip-tilt error through the centroid tracking of bright natural guidestars, is described. / Dissertation/Thesis / Doctoral Dissertation Exploration Systems Design 2019
323

ASSESSMENT OF DISAGGREGATING THE SDN CONTROL PLANE

Adib Rastegarnia (7879706) 20 November 2019 (has links)
Current SDN controllers have been designed based on a monolithic approach that integrates all of services and applications into one single, huge program. The monolithic design of SDN controllers restricts programmers who build management applications to specific programming interfaces and services that a given SDN controller provides, making application development dependent on the controller, and thereby restricting portability of management applications across controllers. Furthermore, the monolithic approach means an SDN controller must be recompiled whenever a change is made, and does not provide an easy way to add new functionality or scale to handle large networks. To overcome the weaknesses inherent in the monolithic approach, the next generation of SDN controllers must use a distributed, microservice architecture that disaggregates the control plane by dividing the monolithic controller into a set of cooperative microservices. Disaggregation allows a programmer to choose a programming language that is appropriate for each microservice. In this dissertation, we describe steps taken towards disaggregating the SDN control plane, consider potential ways to achieve the goal, and discuss the advantages and disadvantages of each. We propose a distributed architecture that disaggregates controller software into a small controller core and a set of cooperative microservices. In addition, we present a software defined network programming framework called Umbrella that provides a set of abstractions that programmers can use for writing of SDN management applications independent of NB APIs that SDN controllers provide. Finally, we present an intent-based network programming framework called OSDF to provide a high-level policy based API for programming of network devices using SDN. <br>
324

Investigation of Out-of-Plane Properties of Interlocking Compressed Earth Block Walls

Herskedal, Nicholas Anthony 01 December 2012 (has links)
Interlocking compressed earth blocks (ICEBs) are cement stabilized soil blocks that allow for dry stacked construction. The incomplete understanding of the inelastic performance of ICEB building systems limits widespread acceptance of this structural system in earthquake prone areas. This thesis presents results from an experimental program designed to explore the behavior of ICEB walls, built according to current design practice in Indonesia and Thailand, and subjected to out-of-plane loading. A total of five reinforced and grouted ICEB walls were constructed and tested. Results from experimentation show the current masonry design code, ACI 530, adequately predicts the yield strength of these walls. However, ACI 530 grossly over-predicts the ICEB wall stiffness. All tests showed flexural behavior and failure, except for one wall. A brittle failure was observed in one wall before reaching the predicted flexural strength, prompting a suggested maximum shear tie spacing. The testing results provide useful data for developing analytical models that predicts the seismic behavior of ICEB walls under out-of-plane loading. A moment-curvature relationship was developed that accurately predicts the behavior of these walls in the elastic range as well as the inelastic range. By comparing the data provided by two walls of similar sizes, one including a pilaster and one without a pilaster, insight into stiffener elements was gained. Analysis of these two walls provides a limit on the length and height of ICEB walls without stiffener elements to prevent significant structural damage during a seismic event. In all, conclusions based on experimental data from ICEB out-of-plane loading tests are aimed to provide suggestions for ICEB construction in areas of high-seismicity.
325

Spatial multivariate design in the plane and on stream networks

Li, Jie 01 December 2009 (has links)
In environmental studies, measurements of interest are often taken on multiple variables. The results of spatial data analyses can be substantially affected by the spatial configuration of the sites where measurements are taken. Hence, optimal designs which result in data guaranteeing efficient statistical inferences need to be studied. We study optimal designs on two large classes of spatial regions with respect to three design criteria, which were prediction, covariance parameter estimation, and empirical prediction. The first class of regions includes those in the plane, where Euclidean distance is used. The performance of the optimal designs is compared to that of randomly chosen designs. Optimal designs for a small example and a relatively large example are obtained. For the small example, complete enumeration of all possible designs is computationally feasible. For the large example, the computational difficulty in searching for the optimal spatial sampling design is overcome by a simulated annealing algorithm. The second class of spatial regions includes streams and rivers, where the distance is defined as distance along the stream network. A moving average construction is used to establish valid covariance and cross-covariance models using stream distance. Optimal designs for small and large examples are obtained. An application of our methodology to a real stream network is included. We discuss the impact of asymmetry in the cross covariance function on the spatial multivariate design. The relationship between multivariate optimal design and univariate optimal design if the multivariate design is restricted to be completely collocated is studied. The efficiency lost if we consider the design that is optimal within the class of collocated designs is discussed.
326

Fabrication and testing of off-plane gratings for future X-ray spectroscopy missions

DeRoo, Casey T 01 August 2016 (has links)
Soft X-ray spectroscopy is a useful observational tool, offering information about high-temperature (10⁶ -- 10⁷ K) astrophysical plasmas and providing useful characterizations of a number of energetic systems, including accreting young stars, cosmic filaments between galaxies, and supermassive black holes. In order to yield high resolution spectra with good signal-to-noise, however, soft X-ray spectrometers must realize improvements in resolving power and effective area through the development of high performance gratings. Off-plane reflection gratings offer the capability to work at high dispersions with excellent throughput, and are a viable candidate technology for future X-ray spectroscopy missions. The off-plane geometry requires a customizable grating meeting distinct fabrication requirements, and a process for producing gratings meeting these requirements has been developed. These fabricated gratings have been evaluated for performance in terms of resolution and diffraction efficiency. Furthermore, these gratings have been conceptually implemented in a soft X-ray spectrometer, the Off-Plane Grating Rocket Experiment (OGRE), whose optical design provides a template for future missions to achieve high performance within a small payload envelope.
327

Spherical wave AVO response of isotropic and anisotropic media: Laboratory experiment versus numerical simulations

Alhussain, Mohammed January 2007 (has links)
A spherical wave AVO response is investigated by measuring ultrasonic reflection amplitudes from a water/Plexiglas interface. The experimental results show substantial deviation from the plane-wave reflection coefficients at large angles. However there is an excellent agreement between experimental data and full-wave numerical simulations performed with the reflectivity algorithm. By comparing the spherical-wave AVO response, modeled with different frequencies, to the plane-wave response, I show that the differences between the two are of such magnitude that three-term AVO inversion based on AVA curvature can be erroneous. I then propose an alternative approach to use critical angle information extracted from AVA curves, and show that this leads to a significant improvement of the estimation of elastic parameters. Azimuthal variation of the AVO response of a vertically fractured model also shows good agreement with anisotropic reflectivity simulations, especially in terms of extracted critical angles which indicated that (1) reflection measurements are consistent with the transmission measurements; (2) the anisotropic numerical simulation algorithm is capable of simulating subtle azimuthal variations with excellent accuracy; (3) the methodology of picking critical angles on seismograms using the inflection point is robust, even in the presence of random and/or systematic noise.
328

Preparation of Clay-dye pigment and its dispersion in polymers

Jamuna, Sivathasan, jsivathasan@yahoo.com January 2008 (has links)
This thesis is concerned with an experimental study of clay intercalation by organic dye molecule which is crucial for the successful development of a stable clay-dye pigment with combined advantages of organic dye and inorganic clay. Clay-dye pigments were prepared by two different methods. Two different organic dyes were used with unmodified clay and modified clay to study the intercalation. Characteristics of clay-dye pigment have been investigated using X-Ray Diffraction, Thermo-gravimetric Analysis and Transmission Electron Microscopy. In this thesis it is shown that the absorption of cationic dye by unmodified clay in aqueous medium mainly takes place in the interlayer clay surface. More likely the dye molecules with aromatic quaternary ammonium cation intercalate the clay layer and strongly interacts with the clay interlayer oxygen plane, where solvent dye (which is hydrophobic in nature) adsorption by unmodified clay mainly takes place on outer surface of the clay. Dye molecules are weakly interacted with outer surface oxygen plane by hydrogen bonding or Vander Waals forces. Modified clay enabled the solvent dye to intercalate inside the clay interlayer surface with the suitable non-aqueous medium (because of its expanded structure). The modified clay suspension in the selected non-aqueous medium shows only partial desorption of alkyl ammonium molecule from the clay layer with the presence of both cationic dye and solvent dye. Therefore the penetrated dye molecules must have weakly interacted with the interlayer oxygen plane as well as the remaining alkyl ammonium molecule present inside the clay layer. It is believed that the thermal and UV stability of organic dye can only be facilitated by a specific interaction (Ĉ-interactions) between aromatic alkyl ammonium cation of organic dye molecule and the interlayer oxygen plane of clay minerals. This interaction possibly enables the high thermal energy or the energy of the UV radiation to transmit immediately into the clay layer. Therefore organic dye molecules are protected from high energy loading and hence thermal and UV stability are improved.
329

INFLUENCE DES ORIENTATIONS CRISTALLINES SUR LA LOCALISATION EN BANDE DE CISAILLEMENT DANS DES ALLIAGES Al-Mg SOUMIS A COMPRESSION PLANE

Chapelle, David 18 December 2002 (has links) (PDF)
L'objet de l'étude est d'appréhender le rôle des orientations cristallines sur l'apparition de la localisation en bandes de cisaillement lorsqu'elle se forme au sein du grain puis lorsqu'elle franchit le joint de grains. La démarche expérimentale s'appuie sur l'exploitation de techniques aujourd'hui classiques –toutefois le couplage l'est moins-, simulation du laminage par channel-die, acquisition d'orientations cristallines par EBSD et mesure de la déformation locale par corrélation d'images sur microgrilles (Bornert [1996]). Sur le plan théorique, la localisation est introduite sous forme de bifurcation, perte d'unicité de la solution, (Hill [1962], Rice [1976]) dans un cristal c.f.c. rigide plastique, se déformant par glissement simple sur les plans de haute densité atomique suivant la loi de Schmid, et dans le cadre de l'hypothèse de Taylor. La cinématique du monocristal est écrite avec le formalisme des grandes transformations (Sidoroff [1982]) sous forme d'une loi constitutive incrémentale linéaire par morceaux. Le bon accord entre observation et modélisation est nettement marqué et deux modes de localisation en bande de cisaillement prédominent : l'un par combinaison de deux systèmes coplanaires, l'autre par combinaison de deux systèmes codirectionnels. Par ailleurs, des phénomènes de germination ont été mis en évidence dans les bandes, signe d'un échauffement dû à de grandes vitesses de glissement.
330

Identification des lois de comportemement élastoplastiques par essais inhomogènes et simulations numériques

Khalfallah, ali 14 February 2004 (has links) (PDF)
Le sujet de thèse que nous abordons concerne l'identification des lois de comportement élastoplastiques anisotropes en vue de leur utilisation pour la simulation numérique des procédés de mise en forme par déformation plastique de tôles minces métalliques d'emboutissage. Nous avons essentiellement contribué à la définition et à la mise en oeuvre de stratégies et techniques d'identification des lois de comportement à partir d'essais expérimentaux. Les essais classiquement utilisés pour l'identification des modèles : la traction simple dans les axes et hors axes, la traction plane et le gonfelement hydraulique sont présentés et analysés du point de vue homogénéité des déformations pour aboutir à la relation contrainte-déformation à partir des mesures globales force-déplacement. L'identification des modèles de comportement à partir des essais inhomogènes nécessite une simulation numérique couplée avec une méthode d'optimisation (méthode du Simplexe) pour minimiser l'écart entre les résultats expérimentaux et la réponse du modèle calculée par une méthode d'élements finis. Nous avons identifié des lois de comportement élastoplastiques anisotropes avec écrouissage isotrope. Ces lois sont basées en particulier sur le choix d'une ou deux fonctions "contrainte équivalente" définissant le critère de plasticité et le potentiel plastique (cadre de la normalité non associée) ayant la même structure que la fonction seuil. Plusieurs critères quadratiques et non quadratiques sont alors utilisés. Nous avons développé une technique spécifique d'analyse de sensibilité des essais par rapport aux differents paramètres à identifier de la loi de comportement. Cette technique est mise en oeuvre sur des exemples pratiques.

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