Dissertations / Theses on the topic 'Mixing or multiple addition'
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Tusche, Marco. "Empirical processes of multiple mixing data." Thesis, Tours, 2013. http://www.theses.fr/2013TOUR4033/document.
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Cette thèse étudie la convergence en loi des processus empiriques de données à mélange multiple. Son contenu correspond aux articles : Durieu et Tusche (2012), Dehling, Durieu, et Tusche (2012), et Dehiing, Durieu et Tusche (2013). Nous suivons l’approche par approximation introduite dans Dehling, Durieu, et Vo1n (2009) et Dehling and Durieu (2011), qui ont établi des théorèmes limite centraux empiriques pour des variables aléatoires dépendants à valeurs dans R ou RAd, respectivement. En développant leurs techniques, nous généralisons leurs résultats à des espaces arbitraires et à des processus empiriques indexés par des classes de fonctions. De plus, nous étudions des processus empiriques séquentiels. Nos résultats s’appliquent aux chaînes de Markov B-géométriquement ergodiques, aux modèles itératifs lipschitziens, aux systèmes dynamiques présentant un trou spectral pour l’opérateur de Perron-Frobenius associé, ou encore, aux automorphismes du tore. Nous établissons des conditions garantissant la convergence du processus empirique de tels modèles vers un processus gaussienThe present thesis studies weak convergence of empirical processes of multiple mixing data. It is based on the articles Durieu and Tusche (2012), Dehling, Durieu, and Tusche (2012), and Dehling, Durieu, and Tusche (2013). We follow the approximating class approach introduced by Dehling, Durieu, and Voln (2009)and Dehling and Durieu (2011), who established empirical central limit theorems for dependent R- and R”d-valued random variables, respectively. Extending their technique, we generalize their results to arbitrary state spaces and to empirical processes indexed by classes of functions. Moreover we study sequential empirical processes. Our results apply to B-geometrically ergodic Markov chains, iterative Lipschitz models, dynamical systems with a spectral gap on the Perron—Frobenius operator, and ergodic toms automorphisms. We establish conditions under which the empirical process of such processes converges weakly to a Gaussian process
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Bishop, Allen J. "Confined Mixing of Multiple Transverse Jets." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/894.
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The mixing performance of multiple transverse jets has been evaluated experimentally. Measurement techniques included laser Doppler velocimetry and planar laser induced fluorescence. Basic findings are consistent with results presented in literature for single jet mixing behavior. Mixing performance has been compared to literature for the single jet case and the Holdeman parameter has been re-evaluated for effectiveness at low jet numbers. A single jet in a confined crossflow was found to have a local minimum at B(d⁄D) = 0.721. Results for two jets indicate monotonically decreasing unmixedness for the range of conditions tested, with no local optimum apparent. Data for three jets indicate a local optimum at B(d⁄D) = 0.87and relatively flat range of mixing performance in the range of 0.75 < B(d⁄D) < 1.5. Six jets indicate a minimum unmixedness near B(d⁄D) = 0.5, but exhibited poorer mixing performance than all other configurations at the highest values of B(d⁄D)tested. The most optimum configuration tested was six jets at B(d⁄D) = 0.5, resulting in an unmixedness of 0.0192. This value was 76% lower than the next lowest configuration (three jets) at the same B(d⁄D).Total momentum was found to collapse the data well, as configurations more closely matched a historical correlation for second moment of a single confined jet more closely.
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Yassawi, Reem. "Multiple mixing of local rank group actions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0015/NQ44636.pdf.
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Yassawi, Reem Adel. "Multiple mixing of local rank group actions." Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=35655.
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Suppose G is a countable, Abelian group with an element of infinite order and let X be a mixing finite rank (rank r) action of G on a probability space, or let X be a mixing beta-local rank action of G with beta > 1/2. Suppose further that the Folner sequence { Fn } indexing the towers of the beta-local X satisfies a "bounded intersection property": there is a constant p such that each Fn can intersect no more than p disjoint translates of itself. If X is finite rank, we also suppose that the cardinalities of the r Folner sequences Fin ri=1 are comparable. We show that X is mixing of all orders. When G = Z, this extends the results of Kalikow and Ryzhikov to a large class of "funny" rank one transformations. We follow Ryzhikov's joining technique in our proof: the main theorem follows from showing that any pairwise independent joining of k copies of X is necessarily product measure. This method generalizes Ryzhikov's technique.
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Cases, Amat Montserrat. "Single and multiple addition to C60. A computational chemistry study." Doctoral thesis, Universitat de Girona, 2003. http://hdl.handle.net/10803/8025.
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Des del seu descobriment, a la molècula C60 se li coneixen una varietat de derivats segons el tipus de funcionalització amb propietats fisicoquímiques específiques de gran interès científic. Una sel·lecció de derivats corresponents a addicions simple o múltiple al C60 s'ha considerat en aquest treball d'investigació. L'estudi a nivell de química computacional de diversos tipus d'addició al C60 s'han portat a terme per tal de poder donar resposta a aspectes que experimentalment no s'entenen o són poc clars.Els sistemes estudiats en referència a l'addició simple al C60 han estat en primer lloc els monoiminoful·lerens, C60NR, (de les dues vies proposades per la seva síntesi, anàlisis cinètic i termodinàmic han ajudat a explicar els mecanismes de formació i justificar l'addició a enllaços tipus [5,6]), i en segon lloc els metanoful·lerens i els hidroful·lerens substituits, C60CHR i C60HR, (raons geomètriques, electròniques, energètiques i magnètiques justifiquen el diferent caràcter àcid ente ambdós derivats tenint en compte una sèrie de substituents R amb diferent caràcter electrònic donor/acceptor). Els fluoroful·lerens, C60Fn, i els epoxid ful·lerens, C60On, (anàlisi sistemàtic dels seus patrons d'addició en base a poder justificar la força que els governa han aportat dades complementàries a les poques que existeixen experimentalment al respecte).
Since the discovery of C60 molecule a large number of derivatives molecules have been described with a great scientific interest of their specific physical and chemical properties. A selection of single and multiple addition products has been considered in this investigation. Study at Computational Chemistry level for this selected derivatives have been carried out in order to give answer to several points that experimentally are not understandable or not enough clear.
As single addition derivatives, firstly were studied the monoiminofullerenes, C60NR, (two routes of synthesis have been considered, kinetic and thermodynamic analysis have help to explain formation mechanisms and justify the possible addition at [5,6]-type bonds), and secondly the methanofullerenes and the substituted hydrofullerenes, C60CHR and C60HR, (geometric, electronic, energetic and magnetic reasons justify the different acid character between both series of derivatives taking care on the influence of R substituents with different donor/acceptor character). The fluorofullerenes, C60Fn, and the epoxide fullerenes, C60On, have been studied as multiple addition derivatives (systematic analysis of the addition pattern have been performed in the way to find reasons to justify the driving force of the multiple addition process).
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Thompson, John Russell. "Multiple four-wave mixing processes in single-mode optical fiber." Diss., Georgia Institute of Technology, 1991. http://hdl.handle.net/1853/30955.
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Ali, Md Shahjahan. "Mixing of a non-buoyant multiple jet group in crossflow." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B29485587.
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Whitton, M. J. "Gas liquid mixing in tall vessels fitted with multiple impellers." Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312190.
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Zhang, Qing. "Multiple recurrence and mixing properties for actions of amenable groups /." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487759436328088.
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Rodgers, Thomas Lawrence. "Multiple-scale approach to understanding formulated product production." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/multiplescale-approach-to-understanding-formulated-product-production(a0de5c77-1bb7-4d7b-af3a-8ccb44a80f42).html.
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Consumer- and pharmaceutical-based products are a major component of the chemical industry. In the personal care industry, formulations often consist of a mixture of surfactants and fatty alcohols. The addition of surfactants aids the stability of the formulation. The formulated product microstructure depends upon the preparation conditions as well as the ingredients. Controlling which microstructures form during the production of a formulated product is important as different microstructures can have wildly different physical properties, making some far more favourable than others. This thesis examines several of the processes undertaken in the manufacture of formulated products. The dissolution of a surfactant in a bulk water phase is examined. This is examined in a number of ways; firstly, the dissolution times of the surfactants are measured using electrical resistance tomography. It is found that the dissolution time varies with the agitation rate, agitator size, and addition method. The dissolution is also examined using dissipative particle dynamics to gain insight into the dissolution on a molecular scale. It is found that the surfactant breaks into wormlike micelles on dissolution. If an oil is added to the initial bulk then the dissolution process is modified so that long cylinders are produced with some spherical micelles. Finally, the break-up rate is predicted using a breakage model based on the agitator shear rate and a network-of-zones model. This produces good results. The production and post-shear processing of a sample formulated product, hair conditioner, is examined. Firstly, the mixing in a vessel is examined with electrical resistance tomography. Problems are encountered when the production method involves the use of distilled water as the conductivity is very low; however, the mixing time of the final product in the vessel can be determined. It is also shown that the majority of the structural changes in the post-shearing process are caused by the in-line rotor-stator mixer. The viscosity of the product increases in a linear fashion with the shear rate, while the conductivity increases as a function of the shear rate and the recycle rate. This allows the monitoring of the post-shearing process to be carried out using electrical resistance tomography. This thesis also looks at the possibility of producing a multiple frequency electrical resistance tomography device to monitor formulated product production; however, it has been shown that the conductivity does not vary with the voltage frequency over a usable range. This meant that no further effort was put into developing this, as it gave no advantage over the traditional single frequency technique. Nevertheless, important advances towards better understanding of mixing processes resulted due to the investigations carried out.
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Luettgen, Christopher O. "An Investigation of the role of mixing conditions during polymeric retention aid addition on the adsorption homogeneity." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/5787.
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Smith, Elwyn D. J. "Noise limits due to light mixing in optical code-division multiple-access systems." Thesis, University of Canterbury. Electrical and Electronic Engineering, 1998. http://hdl.handle.net/10092/5742.
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This thesis is concerned with the performance limits arising in optical code-division multiple-access (OCDMA) networks due to the mixing of light from the independent sources of each user. The scheme of spectral-amplitude OCDMA is shown here to be significantly limited by the phase-induced intensity noise arising from such mixing, and the corresponding signal-to- noise ratio and network capacity limits are of the same order as those arising in coherence-multiplexing systems, also due to such noise. Mixing can only occur between spatially coherent light, and this typically takes place through the combination of the signals into a single-mode fibre. The use of multimode fibre instead of single-mode can thus significantly reduce the levels and effects of phase-induced intensity noise, and this is experimentally demonstrated.
It is shown that in general, assuming independent sources, there are only four possible ways in which to alleviate or eliminate noise limits of the form found for spectral-amplitude OCDMA. These are to separate the signals from each user in either the temporal, spectral, or spatial domains, or else to coherently despread the received signal. Neither spectral separation nor coherent de spreading are practical for spectral-amplitude OCDMA, but spatial separation via multimode fibre may be applied. The use of pulse-position modulation (PPM) with spectral-amplitude OCDMA is shown to be able to improve the performance beyond the limits found earlier, and this is because of the temporal separation it introduces. However, unlike the direct reduction of source duty cycle, PPM signalling can be applied without increasing, relative to the bit rate, the modulation or detection bandwidths, nor the dispersion sensitivity. Such PPM signalling and the associated decoding can also be applied to other similarly limited systems, including those based upon coherence multiplexing.
If an OCDMA system is incoherent, has independent sources of the same spectrum, and has only a single-mode fibre to and from each user, then it can only avoid the significant noise limits found for spectral-amplitude OCDMA by the temporal separation of the signals from each user. This is the case for incoherent unipolar OCDMA systems, since the sparse codes of these systems rely on such temporal separation. Bipolar codes are not sparse, and in bipolar systems there is ordinarily no significant temporal separation between the signals from each user. Consequently, assuming sole single-mode-fibre paths and independent sources with identical spectra, every incoherent bipolar OCDMA system must encounter performance limits at least as bad as those found for spectral-amplitude OCDMA. These worst-case limits are identified for each of the incoherent bipolar OCDMA proposals to date.
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Heeb, Thomas Gregory. "Examination of turbulent mixing with multiple second order chemical reactions by the statistical analysis technique /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487267024995615.
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Tani, Yosuke. "Catalytic Addition of Functionalities across Carbon-Carbon Multiple Bonds with Carbon Dioxide and Related Electrophiles." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199321.
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Gattobigio, Giovanni Luca. "Manipulation of a large magneto-optical trap : application to four-wave mixing." Nice, 2008. http://www.theses.fr/2008NICE4022.
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Casey, Timothy. "The aerodynamic losses with the addition of film cooling in a high-speed annular cascade." Honors in the Major Thesis, University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/1375.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Engineering and Computer Science
Mechanical Engineering
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Gattobigio, Giovanni Luca. "Manipulation of a Large Magneto-Optical Trap:application to Four-Wave Mixing." Phd thesis, Université de Nice Sophia-Antipolis, 2008. http://tel.archives-ouvertes.fr/tel-00312718.
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Dans cette thèse, nous présentons une recherche expérimentale détaillée des lois caract érisant la taille et la densité atomique de grands pièges magnéto-optiques contenant typiquement 10^10 atomes. Il est bien connu que les interactions induites par laser, produites par la diffusion multiple, y constituent la limitation principale à l'obtention de densités atomiques élevées. Pour contourner cette limite, nous avons réalisé un piège magnéto-optique 'noir' combiné un piège dipolaire. Les forces de répulsion assistées par la lumière ont ainsi pu être considérablement réduites et une augmentation de près de deux ordres des grandeur sur le densité (jusqu'à 10^12 atm/cm^3) a été corrélativement observée. Nous avons proposé également un modèle qualitatif pour rendre compte de la densité atomique (et également pour la taille) o`u nous avons introduit les interactions mécaniques induites par les photons du laser repompeur quand son épaisseur optique devient importante. Ce travail fait partie d'un projet de recherche qui vise à terme à observer la localisation d'Anderson de la lumière dans des nuages d'atomes froids, mais pour laquelle des densités de l'ordre (10^13-10^14 atm/cm^3) sont requises. Pour des densités inférieures, des mécanismes de gain peuvent toutefois être mis à profit pour amplifier des modes pre-localisés. Nous avons, ainsi, mis en place une technique pompe-sonde pour la création d'un gain dans l'échantillon atomique. La configuration des pompes a autorisé l'observation du signal de mélange a quatre ondes. Une analyse détaillée de ses propriétés et de ses caractéristiques a été présentée. En particulier, une asymétrie rouge-bleu dans le spectre, pour des intensités élevées des faisceaux pompes, a été mise en évidence. Cette asymétrie a pu tre expliquée en tenant compte du regroupement des atomes dans les noeuds ou dans les ventres de l'onde stationnaire des faisceaux de pompe.
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Azizoglu, Suha Alp. "Time Domain Scattering From Single And Multiple Objects." Phd thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12609413/index.pdf.
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The importance of the T-matrix method is well-known when frequency domain scattering problems are of interest. With the relatively recent and wide-spread interest in time domain scattering problems, similar applications of the T-matrix method are expected to be useful in the time domain. In this thesis, the time domain spherical scalar wave functions are introduced, translational addition theorems for the time domain spherical scalar wave functions necessary for the solution of multiple scattering problems are given, and the formulation of time domain scattering of scalar waves by two spheres and by two scatterers of arbitrary shape is presented. The whole analysis is performed in the time domain requiring no inverse Fourier integrals to be evaluated. Scattering examples are studied in order to check the numerical accuracy, and demonstrate the utility of the expressions.
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Suberg, Lavinia A. "Investigations of the variability of tidal mixing fronts and their importance for shelf-sea ecosystems across multiple trophic levels." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/400389/.
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Tidal mixing fronts establish during the summer months over shelf-seas, and separate tidally-mixed from stratified water masses. They play an important part in shelf-sea bio-physical processes, including volume transport and facilitation of primary productivity. Frontal hydrodynamics provide the physical necessities for prey aggregations to develop, holding the potential for biodiversity hotspots. However, there is limited knowledge on long-term variability of tidal mixing fronts and its effect on associated ecosystems, due to a lack of adequate datasets. Such information would greatly benefit spatial conservation efforts and improve our understanding of ecosystem dynamics on the continental shelf. Satellite-derived frontal maps and extensive biological datasets (from 1990-2010) are employed here to investigate spatio-temporal variability of tidal mixing fronts and their significance for shelf-sea biology from zooplankton tomegavertebrates in the Celtic Sea. In addition, this study assesses the suitability and limitations of satellite-derived frontal metrics for quantitative analyses and employs innovative technology (submarine gliders) to fill data gaps in species-environment interactions. This research provides guidance on the use of frontal metrics in quantitative analysis, such as the need to account for data variability over the years and the careful consideration of the employed frontal metric. This thesis furthermore, represents the first description of long-term temporal variability of tidal mixing fronts on the European shelf and highlights a potential sensitivity to climate change due to positive correlations with rising temperatures. Consequences could include extension of the frontal season and intensification of the frontal density gradient with knock-on effects on associated biota. The density gradient of tidal mixing fronts was shown to act as a direct distribution boundary for plankton between different shelf-sea domains. Climate-change-driven shifts in the seasonality of these fronts may have a direct impact on dispersal of passive floating organisms, habitat connectivity and adult populations of species with planktonic larvae, including commercially important fish and the benthos. Apart from a barrier function, fronts were also found to be important foraging areas for specialist megavertebrates, which were strongly associated with persistent frontal areas, whereas generalist feeders were not. Tidal mixing fronts represent suitable conservation areas for sensitive species in shelf-seas. The underlying mechanisms leading to bio-aggregations at these sites require more research. High-resolution data, simultaneously collected across multiple trophic levels can be obtained by autonomous robotic fleets in the near future.
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Hinch, Garry Dale. "Effect of ligand addition and substitution on metal-metal multiple bonds: Direct electronic structure comparisons via gas phase photoelectron spectroscopy." Diss., The University of Arizona, 1990. http://hdl.handle.net/10150/185132.
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Several series of complexes containing metal-metal and metal-heteroatom multiple bonds have been examined via gas-phase photoelectron spectroscopy to study the electronic structure effects resulting from simple ligand addition or substitution. Two types of complexes containing metal-metal multiple bonds form the basis of this study: complexes containing the M₂X₄P₄ core (where M = Mo, Re; X = halogen, Me; and P₄ = (PMe₃)₄ or [R₂P(CH₂)ₓPR₂]₂) and the dinuclear cyclopentadienyl metal carbonyl complexes [CpM(CO)ₓ]₂ (where M = Cr, Mo, W and x = 2,3). In the M₂X₄P₄ dimers two basic substitutions were examined. One involved changing the degree of rotation between the metal centers by varying the chelating phosphine ligand bridging the two centers. The other substitution involved varying the X ligand among Cl, Br, I, and Me on Mo₂ and Re₂ complexes with a monodentate phosphine, PMe₃. The synthesis and characterization of Re₂I₄ (PMe₃)₄, a previously unreported member of this series, is also described. For both of these substitutions, only very small changes were seen in the energy of the ionizations from orbitals involved in the metal-metal multiple bond. In the chelating phosphine complexes, changes in bandshape of the metal-based ionizations can be explained through the reduction in symmetry caused by placing the metals in a "staggered" configuration. For the monodentate phosphine complexes, the direction of the energy shifts which do occur indicate that changes in π-donor capability of the X ligand affect the metal-metal bonding to a greater extent than the changes in σ-donor capability. The effects of ligand addition to a metal-metal multiple bond (as in (CpM(CO)₂)₂) were examined, first by addition of one CO/metal, and then by insertion of a heteroatom into the multiple bond. In both cases, substantial energy shifts occur in related metal-based ionizations upon ligand addition. With CO addition, the M-M σ ionization is destabilized by ca. 1-2 eV, correlating with the longer M-M distances and increased reactivity in the (CpM(CO)₃)₂ systems. With the insertion of a chalcogen (S,Se) atom into the M-M triple bond of (CpCr(CO)₂)₂, the π-donor capability of the chalcogen results in M-heteroatom multiple bond character, though the PE spectra suggest that a full triple bond is not present.
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Martinez, Jorge L. "Revealing groundwater-surface water exchanges and recharge processes with multiple tracers and hydrochemistry." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/110526/1/Jorge_Martinez_Thesis.pdf.
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For effective resource management and to establish groundwater and surface water interactions, an innovative range of hydrological tracers and hydrochemical techniques have been applied to a total catchment in southeast Queensland. Stable and radioisotopes, carbon-14, radon-222, noble gases and SF6 were analyzed to characterize and quantify recharge sources. Statistical methods were also combined with inverse geochemical and three-dimensional geological modelling techniques, to develop regional conceptual models of groundwater movement and interaction with rivers.
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Yapici, Kerim. "Numerical Investigation Of Stirred Tank Hydrodynamics." Master's thesis, METU, 2003. http://etd.lib.metu.edu.tr/upload/1302140/index.pdf.
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A theoretical study on the hydrodynamics of mixing processes in stirred tanks is described. The primary objective of this study is to investigate flow field and power consumption generated by the six blades Rushton turbine impeller in baffled, flat-bottom cylindrical tank both at laminar and turbulent flow regime both qualitatively and quantitatively. Experimental techniques are expensive and time consuming in characterizing mixing processes. For these reasons, computational fluid dynamics (CFD) has been considered as an alternative method. In this study, the velocity field and power requirement are obtained using FASTEST, which is a CFD package. It employs a fully conservative second order finite volume method for the solution of Navier-Stokes equations. The inherently time-dependent geometry of stirred vessel is simulated by a multiple frame of reference approach. The flow field obtained numerically agrees well with those published experimental measurements. It is shown that Rushton turbine impeller creates predominantly radial jet flow pattern and produces two main recirculation flows one above and the other below the impeller plane. Throughout the tank impeller plane dimensionless radial velocity is not affected significantly by the increasing impeller speed and almost decreases linearly with increase in radial distance. Effect of the baffling on the radial and tangential velocities is also investigated. It is seen that tangential velocity is larger than radial velocity at the same radial position in unbaffled system. An overall impeller performance characteristic like power number is also found to be in agreement with the published experimental data. Also power number is mainly affected by the baffle length and increase with increase in baffle length. It is concluded that multiple frame of reference approach is suitable for the prediction of flow pattern and power number in stirred tank.
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Cooper, James Roger. "A Multi-Wilkinson Power Divider Based Complex Reflection Coefficient Detector." Scholar Commons, 2010. https://scholarcommons.usf.edu/etd/1603.
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In the field of applied electromagnetics, there is always a need to create new methods for electrical characterization of materials, systems, devices, etc. Many applications need small and/or inexpensive equipment in performing these characterizations. The current method for making measurements of electrical properties at frequencies above 300 MHz, the transmission/reflection method, has severe limitations in these areas due large size and high price of the necessary equipment for making them. Therefore, presented herein is the conceptualization, design and analysis of a complex reflection coefficient detector which is relatively small, lightweight, and inexpensive.
A reflection coefficient detector is a device designed to isolate and compare a driving signal against a reflected signal. The reflection of the second signal is caused by a mismatch between the device's output impedance and a load's input impedance. By comparing the driving, or transmitted, signal and the reflected signal, the reflection coefficient at the boundary can be calculated. This coefficient can be used to calculate a load's input impedance, or a material's permittivity when combined with an attached probe's characteristics.
The reflection coefficient detector presented is built using microstrip and surface mount components. This makes the device comparably cheap. Its design is based upon five Wilkinson Power Dividers which lends itself to be scaled down for implementation in on-chip, and other micro- and nano- scale systems.
The accuracy and functionality of the device will be demonstrated through the use of S-Parameters measurements and CAD simulations. Through this, it will be shown that the device is a practical form of making measurements in applications which are otherwise restricted to certain limitations. In closing, applications, alternative designs and future advancements of the complex reflection coefficient detector will be discussed.
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Ernst, Romuald. "Dynamique des opérateurs sur les Grassmanniennes." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00949228.
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Les travaux présentés dans cette thèse concernent la dynamique d'opérateurs pour des sous-espaces. Nous étudions principalement deux notions de dynamique pour des sous-espaces qui sont la n-supercyclicité et la forte n-supercyclicité. Dans une première partie, nous étudions l'existence de tels opérateurs dans le cadre des espaces de dimension finie et nous exhibons les indices de supercyclicité admissibles pour des espaces réels de dimension finie. Dans une deuxième partie, nous étudions en détail les opérateurs fortement n-supercycliques en exhibant leurs propriétés spectrales et en donnant des caractérisations pour certaines classes d'opérateurs. Nous détaillons ensuite une nouvelle notion de dynamique pour des sous-espaces de codimension finie et nous étudions les propriétés de tels opérateurs, en particulier le lien "dual" avec les opérateurs fortement n-supercycliques. Enfin, nous terminons avec une caractérisation des opérateurs chaotiques sur certains types d'espaces de suites sans base inconditionnelle, un critère de supercyclicité pour des opérateurs non-bornés et une condition suffisante pour obtenir un opérateur multiple mélangeant de tout degré.
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Hajjar, Redouane. "RMN de l'interaction quadripolaire au second ordre d'un solide en rotation : théorie, simulation et application du MQMAS aux catalyseurs solides." Paris 6, 2007. http://www.theses.fr/2007PA066614.
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L’objectif de cette thèse est l’étude de l’interaction quadripolaire en RMN et l’application de la spectroscopie haute résolution MQMAS (Multiple Quantum Magic Angle Spinning) à des matériaux catalytiques. Nous avons mis au point des feuilles de calcul MATHEMATICA qui déterminent de façon automatique les expressions analytiques des tenseurs sphériques V(2,0), W(2,0) et W(4,0) du gradient de champ électrique. Puis nous avons également mis au point des feuilles de calcul pour simuler l’intensité d’une cohérence donnée d’un spin I demi-entier dans un solide (statique ou en rotation MAS) et excité par une impulsion ou par une séquence MQMAS. Nous avons mené une étude par simulation et une autre expérimentale pour éclaircir la différence dans la littérature sur les phases de la troisième impulsion de la séquence SPAM (Soft Pulse Added Mixing). Cette séquence (en particulier la séquence SPAM tronquée) et sa variante Multiplex augmentent nettement le rapport S/B en MQMAS. Nous avons appliqué des séquences MQMAS aux noyaux quadripolaires (27Al et 51V) dans des matériaux catalytiques (Al-SBA-15 et Vx-SiBEA) et nous avons montré l’intérêt d’une part des cohérences 5Q et d’autre part celui du cyclage de phase Multiplex.
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Baillot, Maxime. "Mélange à quatre ondes multiple pour le traitement tout-optique du signal dans les fibres optiques non linéaires." Thesis, Rennes 1, 2017. http://www.theses.fr/2017REN1S068/document.
Full textAbstract:
Le mélange à quatre ondes est un effet non linéaire sensible à la phase qui suscite de nombreux intérêts dans le domaine de la génération de peignes de fréquences et du traitement tout optique du signal par exemple. Un peigne de fréquences peut en effet s'obtenir par effet de mélange à quatre ondes 1en cascade. Dans ce cas, un nombre N d'ondes interagissent entre elles via l'effet Kerr et la modélisation d'un tel processus doit tenir compte de tous les couplages possibles entre les ondes. Au cours de mes travaux de thèse, je me suis intéressé, dans un premier temps, à la modélisation du mélange à quatre ondes dit multiple pour lequel un nombre quelconque N d'ondes interagissent entre elles. J'ai proposé une formulation générale permettant d'identifier simplement tous les termes de mélange à quatre ondes issus de toutes les combinaisons possibles de couplage entre les ondes et leur désaccord de phase associé. J'ai validé cette approche en proposant une étude théorique et expérimentale d'un processus de mélange à quatre ondes multiple dans une fibre optique non linéaire. Dans une deuxième partie, j'ai proposé, grâce au modèle élaboré précédemment, une étude théorique du phénomène de conversion de fréquence sensible à la phase, permettant la décomposition des composantes en quadrature d'un signal optique. Dans la littérature, cette expérience fut démontrée initialement avec quatre ondes pompes et dans plusieurs types de composants non linéaires. J'ai pu démontrer, au cours de mes travaux, que trois pompes étaient suffisantes pour réaliser l'expérience et j'ai déterminé des relations analytiques simples permettant de choisir les paramètres expérimentaux (notamment l'amplitude et la phase des pompes) rendant possible la décomposition des composantes en quadrature d'un signal. J'ai validé cette étude par la démonstration expérimentale d'un convertisseur de fréquence sensible à la phase avec uniquement trois pompes et j'ai étudié théoriquement les effets de la dispersion chromatique sur les performances du convertisseur de fréquence. Enfin, dans une dernière partie, j'ai caractérisé des fibres optiques microstructurées en verre de chalcogénure fabriquées dans le cadre d'une collaboration avec Perfos, l'Institut des Sciences Chimiques de Rennes et SelenOptics. Dans ce cadre, j'ai mis en place un banc de mesure de la dispersion chromatique et du coefficient non linéaire des fibres optiques basé sur le mélange à quatre ondesFour-wave mixing is a phase-sensitive nonlinear effect that arouses interest, particularly in the fields of frequency comb generation and all-optical signal processing. As an example, frequency combs can be produced thanks to a cascaded four-wave mixing process. In this case, N waves can interact with each other through the optical Kerr effect, and one has to take into account all the possible interactions to be able to adequately model the process. During my PhD thesis, I was interested in modeling the so-called multiple four-wave mixing process, in which any number N of waves can interact with each other. I proposed a general formulation that allows to easily identify all the four-wave mixing terms originating from all the possible combinations of wave coupling and their associated phase-mismatch terms. I validated this approach through the theoretical and experimental study of a multiple four-wave mixing process in a nonlinear optical fiber. Thanks to the developed model, I then proposed a theoretical study of the phase-sensitive frequency conversion process, which permits to demultiplex the quadrature components of an optical signal. In the literature, this process was first experimentally demonstrated in several nonlinear devices using four pump waves. I demonstrated that only three pump waves were required to successfully perform the experiment, and I determined the simple analytical relations from which the adequate experimental parameters (namely, the amplitudes and phases of the pump waves) could be deduced. I finally validated this study by experimentally demonstrating a phase-sensitive frequency conversion process with only three pump waves, and I theoretically studied the influence of chromatic dispersion on the performance of this frequency converter. Finally, I characterized some chalcogenide microstructured optical fibers that were fabricated in the framework of a collaboration with Perfos, the Institut des Sciences Chimiques de Rennes, and SelenOptics. I set up a test bench based on the four-wave mixing process in order to measure the chromatic dispersion and nonlinear coefficient of some optical fibers
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Jamet, Sophie. "Effet photoréfractif dans l'InP:Fe : étude comparative en fonction de la température à plusieurs longueurs d'onde." Rouen, 1995. http://www.theses.fr/1995ROUES002.
Full textAbstract:
Cette étude porte sur l'effet photoréfractif dans le phosphure d'indium dopé au fer (InP:Fe). Les gains optiques mesurés en absence de champ électrique appliqué et à la longueur d'onde de 1,06 micromètre sont plus faibles que les valeurs calculées avec un modèle qui tient compte d'un seul niveau d'énergie (celui du fer) dans la bande interdite. Nous contribuons à déterminer l'origine de cette réduction qui est attribuée dans la littérature, soit aux transitions indirectes liées à l'état excité du fer soit à d'autres niveaux superficiels. Dans un premier temps, nous mettons en évidence la nécessité d'effectuer des mesures en fonction de la température et à plusieurs longueurs d'onde (1,06 ; 1,32 et 1,535 micromètre) afin d'établir les rôles respectifs des différents niveaux d'énergie dans les échantillons étudiés où l'effet photoréfractif est dominé par les trous à température ambiante. L'étude de la constante de temps d'effacement du réseau a permis de déterminer les concentrations en ions Fe2+ et Fe3+. Nous comparons ensuite les courbes du gain mesuré pour les trois longueurs d'onde en fonction de la température et du pas avec les simulations effectuées à partir des différents modèles comprenant soit le niveau excité du Fe2+*, soit un second niveau placé près de la bande de conduction puis, près de la bande de valence. Dans les échantillons étudiés, ces différentes comparaisons ont montré qu'à basse température l'effet photoréfractif est influencé par un second niveau situé près de la bande de valence alors qu'à température ambiante il faut à la fois tenir compte du second défaut et de l'état excité du fer
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Sarrazin-Baudoux, Christine. "Etude du mixage ionique dans un système à grande limite de solubilité : cas du Cuivre-Nickel, caractérisation de l'adhérence de ces revêtements sur substrat acier." Poitiers, 1987. http://www.theses.fr/1987POIT2305.
Full textAbstract:
Elaboration de la technique de melange ionique associant l'evaporation de couches minces successives et l'implantation ionique. Etude du melange ionique des multicouches cu-ni. Mise en evidence de deux phenomenes principaux de diffusion en fonction de la temperature. Analyse des phases formees lors du melange ionique. Application de la technique de melange ionique comme procede de depot
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Jaouen, Christiane. "Etude des mécanismes des transformations de phase induites par irradiation aux ions dans les systèmes métalliques." Poitiers, 1987. http://www.theses.fr/1987POIT2019.
Full textAbstract:
Etude par mesure de conductivite electrique, par retrodiffusion rutherford et par microscopie ionique en transmission des differents aspects du melange ionique dans le systeme mt/al (mt=fe, co, ni) et fe-mg. Analyse des differents facteurs controlant la formation d'une phase et celle d'une phase amorphe. Analyse des mecanismes de transformation cristal-amorphe de l'alliage ni::(50)al::(50) en couche mince. Influence des parametres d'irradation sur cette transformation
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Kokkalis, Efstratios. "Fluid dynamic assessments of spiral flow induced by vascular grafts." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/5b96492f-983f-4baa-8e48-20da6939e65c.
Full textAbstract:
Peripheral vascular grafts are used for the treatment of peripheral arterial disease and arteriovenous grafts for vascular access in end stage renal disease. The development of neo-intimal hyperplasia and thrombosis in the distal anastomosis remains the main reason for occlusion in that region. The local haemodynamics produced by a graft in the host vessel is believed to significantly affect endothelial function. Single spiral flow is a normal feature in medium and large sized vessels and it is induced by the anatomical structure and physiological function of the cardiovascular system. Grafts designed to generate a single spiral flow in the distal anastomosis have been introduced in clinical practice and are known as spiral grafts. In this work, spiral peripheral vascular and arteriovenous grafts were compared with conventional grafts using ultrasound and computational methods to identify their haemodynamic differences. Vascular-graft flow phantoms were developed to house the grafts in different surgical configurations. Mimicking components, with appropriate acoustic properties, were chosen to minimise ultrasound beam refraction and distortion. A dual-beam two-dimensional vector Doppler technique was developed to visualise and quantify vortical structures downstream of each graft outflow in the cross-flow direction. Vorticity mapping and measurements of circulation were acquired based on the vector Doppler data. The flow within the vascular-graft models was simulated with computed tomography based image-guided modelling for further understanding of secondary flow motions and comparison with the experimental results. The computational assessments provided a three-dimensional velocity field in the lumen of the models allowing a range of fluid dynamic parameters to be predicted. Single- or double-spiral flow patterns consisting of a dominant and a smaller vortex were detected in the outflow of the spiral grafts. A double- triple- or tetra-spiral flow pattern was found in the outflow of the conventional graft, depending on model configuration and Reynolds number. These multiple-spiral patterns were associated with increased flow stagnation, separation and instability, which are known to be detrimental for endothelial behaviour. Increased in-plane mixing and wall shear stress, which are considered atheroprotective in normal vessels, were found in the outflow of the spiral devices. The results from the experimental approach were in agreement with those from the computational approach. This study applied ultrasound and computational methods to vascular-graft phantoms in order to characterise the flow field induced by spiral and conventional peripheral vascular and arteriovenous grafts. The results suggest that spiral grafts are associated with advanced local haemodynamics that may protect endothelial function and thereby may prevent their outflow anastomosis from neo-intimal hyperplasia and thrombosis. Consequently this work supports the hypothesis that spiral grafts may decrease outflow stenosis and hence improve patency rates in patients.
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Hitchcock, Yvonne Roslyn. "Elliptic curve cryptography for lightweight applications." Thesis, Queensland University of Technology, 2003. https://eprints.qut.edu.au/15838/1/Yvonne_Hitchcock_Thesis.pdf.
Full textAbstract:
Elliptic curves were first proposed as a basis for public key cryptography in the mid 1980's. They provide public key cryptosystems based on the difficulty of the elliptic curve discrete logarithm problem (ECDLP) , which is so called because of its similarity to the discrete logarithm problem (DLP) over the integers modulo a large prime. One benefit of elliptic curve cryptosystems (ECCs) is that they can use a much shorter key length than other public key cryptosystems to provide an equivalent level of security. For example, 160 bit ECCs are believed to provide about the same level of security as 1024 bit RSA. Also, the level of security provided by an ECC increases faster with key size than for integer based discrete logarithm (dl) or RSA cryptosystems. ECCs can also provide a faster implementation than RSA or dl systems, and use less bandwidth and power. These issues can be crucial in lightweight applications such as smart cards. In the last few years, ECCs have been included or proposed for inclusion in internationally recognized standards. Thus elliptic curve cryptography is set to become an integral part of lightweight applications in the immediate future. This thesis presents an analysis of several important issues for ECCs on lightweight devices. It begins with an introduction to elliptic curves and the algorithms required to implement an ECC. It then gives an analysis of the speed, code size and memory usage of various possible implementation options. Enough details are presented to enable an implementer to choose for implementation those algorithms which give the greatest speed whilst conforming to the code size and ram restrictions of a particular lightweight device. Recommendations are made for new functions to be included on coprocessors for lightweight devices to support ECC implementations Another issue of concern for implementers is the side-channel attacks that have recently been proposed. They obtain information about the cryptosystem by measuring side-channel information such as power consumption and processing time and the information is then used to break implementations that have not incorporated appropriate defences. A new method of defence to protect an implementation from the simple power analysis (spa) method of attack is presented in this thesis. It requires 44% fewer additions and 11% more doublings than the commonly recommended defence of performing a point addition in every loop of the binary scalar multiplication algorithm. The algorithm forms a contribution to the current range of possible spa defences which has a good speed but low memory usage. Another topic of paramount importance to ECCs for lightweight applications is whether the security of fixed curves is equivalent to that of random curves. Because of the inability of lightweight devices to generate secure random curves, fixed curves are used in such devices. These curves provide the additional advantage of requiring less bandwidth, code size and processing time. However, it is intuitively obvious that a large precomputation to aid in the breaking of the elliptic curve discrete logarithm problem (ECDLP) can be made for a fixed curve which would be unavailable for a random curve. Therefore, it would appear that fixed curves are less secure than random curves, but quantifying the loss of security is much more difficult. The thesis performs an examination of fixed curve security taking this observation into account, and includes a definition of equivalent security and an analysis of a variation of Pollard's rho method where computations from solutions of previous ECDLPs can be used to solve subsequent ECDLPs on the same curve. A lower bound on the expected time to solve such ECDLPs using this method is presented, as well as an approximation of the expected time remaining to solve an ECDLP when a given size of precomputation is available. It is concluded that adding a total of 11 bits to the size of a fixed curve provides an equivalent level of security compared to random curves. The final part of the thesis deals with proofs of security of key exchange protocols in the Canetti-Krawczyk proof model. This model has been used since it offers the advantage of a modular proof with reusable components. Firstly a password-based authentication mechanism and its security proof are discussed, followed by an analysis of the use of the authentication mechanism in key exchange protocols. The Canetti-Krawczyk model is then used to examine secure tripartite (three party) key exchange protocols. Tripartite key exchange protocols are particularly suited to ECCs because of the availability of bilinear mappings on elliptic curves, which allow more efficient tripartite key exchange protocols.
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Hitchcock, Yvonne Roslyn. "Elliptic Curve Cryptography for Lightweight Applications." Queensland University of Technology, 2003. http://eprints.qut.edu.au/15838/.
Full textAbstract:
Elliptic curves were first proposed as a basis for public key cryptography in the mid 1980's. They provide public key cryptosystems based on the difficulty of the elliptic curve discrete logarithm problem (ECDLP) , which is so called because of its similarity to the discrete logarithm problem (DLP) over the integers modulo a large prime. One benefit of elliptic curve cryptosystems (ECCs) is that they can use a much shorter key length than other public key cryptosystems to provide an equivalent level of security. For example, 160 bit ECCs are believed to provide about the same level of security as 1024 bit RSA. Also, the level of security provided by an ECC increases faster with key size than for integer based discrete logarithm (dl) or RSA cryptosystems. ECCs can also provide a faster implementation than RSA or dl systems, and use less bandwidth and power. These issues can be crucial in lightweight applications such as smart cards. In the last few years, ECCs have been included or proposed for inclusion in internationally recognized standards. Thus elliptic curve cryptography is set to become an integral part of lightweight applications in the immediate future. This thesis presents an analysis of several important issues for ECCs on lightweight devices. It begins with an introduction to elliptic curves and the algorithms required to implement an ECC. It then gives an analysis of the speed, code size and memory usage of various possible implementation options. Enough details are presented to enable an implementer to choose for implementation those algorithms which give the greatest speed whilst conforming to the code size and ram restrictions of a particular lightweight device. Recommendations are made for new functions to be included on coprocessors for lightweight devices to support ECC implementations Another issue of concern for implementers is the side-channel attacks that have recently been proposed. They obtain information about the cryptosystem by measuring side-channel information such as power consumption and processing time and the information is then used to break implementations that have not incorporated appropriate defences. A new method of defence to protect an implementation from the simple power analysis (spa) method of attack is presented in this thesis. It requires 44% fewer additions and 11% more doublings than the commonly recommended defence of performing a point addition in every loop of the binary scalar multiplication algorithm. The algorithm forms a contribution to the current range of possible spa defences which has a good speed but low memory usage. Another topic of paramount importance to ECCs for lightweight applications is whether the security of fixed curves is equivalent to that of random curves. Because of the inability of lightweight devices to generate secure random curves, fixed curves are used in such devices. These curves provide the additional advantage of requiring less bandwidth, code size and processing time. However, it is intuitively obvious that a large precomputation to aid in the breaking of the elliptic curve discrete logarithm problem (ECDLP) can be made for a fixed curve which would be unavailable for a random curve. Therefore, it would appear that fixed curves are less secure than random curves, but quantifying the loss of security is much more difficult. The thesis performs an examination of fixed curve security taking this observation into account, and includes a definition of equivalent security and an analysis of a variation of Pollard's rho method where computations from solutions of previous ECDLPs can be used to solve subsequent ECDLPs on the same curve. A lower bound on the expected time to solve such ECDLPs using this method is presented, as well as an approximation of the expected time remaining to solve an ECDLP when a given size of precomputation is available. It is concluded that adding a total of 11 bits to the size of a fixed curve provides an equivalent level of security compared to random curves. The final part of the thesis deals with proofs of security of key exchange protocols in the Canetti-Krawczyk proof model. This model has been used since it offers the advantage of a modular proof with reusable components. Firstly a password-based authentication mechanism and its security proof are discussed, followed by an analysis of the use of the authentication mechanism in key exchange protocols. The Canetti-Krawczyk model is then used to examine secure tripartite (three party) key exchange protocols. Tripartite key exchange protocols are particularly suited to ECCs because of the availability of bilinear mappings on elliptic curves, which allow more efficient tripartite key exchange protocols.
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Tavares, Lucas Alves. "O envolvimento da proteína adaptadora 1 (AP-1) no mecanismo de regulação negativa do receptor CD4 por Nef de HIV-1." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/17/17136/tde-06012017-113215/.
Full textAbstract:
O Vírus da Imunodeficiência Humana (HIV) é o agente etiológico da Síndrome da Imunodeficiência Adquirida (AIDS). A AIDS é uma doença de distribuição mundial, e estima-se que existam atualmente pelo menos 36,9 milhões de pessoas infectadas com o vírus. Durante o seu ciclo replicativo, o HIV promove diversas alterações na fisiologia da célula hospedeira a fim de promover sua sobrevivência e potencializar a replicação. A rápida progressão da infecção pelo HIV-1 em humanos e em modelos animais está intimamente ligada à função da proteína acessória Nef. Dentre as diversas ações de Nef está a regulação negativa de proteínas importantes na resposta imunológica, como o receptor CD4. Sabe-se que esta ação resulta da indução da degradação de CD4 em lisossomos, mas os mecanismos moleculares envolvidos ainda são totalmente elucidados. Nef forma um complexo tripartite com a cauda citosólica de CD4 e a proteína adaptadora 2 (AP-2), em vesículas revestidas por clatrina nascentes, induzindo a internalização e degradação lisossomal de CD4. Pesquisas anteriores demonstraram que o direcionamento de CD4 aos lisossomos por Nef envolve a entrada do receptor na via dos corpos multivesiculares (MVBs), por um mecanismo atípico, pois, embora não necessite da ubiquitinação de carga, depende da ação de proteínas que compõem os ESCRTs (Endosomal Sorting Complexes Required for Transport) e da ação de Alix, uma proteína acessória da maquinaria ESCRT. Já foi reportado que Nef interage com subunidades dos complexos AP-1, AP-2, AP-3 e Nef não parece interagir com subunidades de AP-4 e AP-5. Entretanto, o papel da interação de Nef com AP-1 e AP-3 na regulação negativa de CD4 ainda não está totalmente elucidado. Ademais, AP-1, AP-2 e AP-3 são potencialmente heterogêneos devido à existência de isoformas múltiplas das subunidades codificadas por diferentes genes. Todavia, existem poucos estudos para demonstrar se as diferentes combinações de isoformas dos APs são formadas e se possuem propriedades funcionais distintas. O presente trabalho procurou identificar e caracterizar fatores celulares envolvidos na regulação do tráfego intracelular de proteínas no processo de regulação negativa de CD4 induzido por Nef. Mais especificamente, este estudo buscou caracterizar a participação do complexo AP-1 na modulação negativa de CD4 por Nef de HIV-1, através do estudo funcional das duas isoformas de ?-adaptina, subunidades de AP-1. Utilizando a técnica de Pull-down demonstramos que Nef é capaz de interagir com ?2. Além disso, nossos dados de Imunoblot indicaram que a proteína ?2-adaptina, e não ?1-adaptina, é necessária no processo de degradação lisossomal de CD4 por Nef e que esta participação é conservada para degradação de CD4 por Nef de diferentes cepas virais. Ademais, por citometria de fluxo, o silenciamento de ?2, e não de ?1, compromete a diminuição dos níveis de CD4 por Nef da membrana plasmática. A análise por imunofluorêsncia indireta também revelou que a diminuição dos níveis de ?2 impede a redistribuição de CD4 por Nef para regiões perinucleares, acarretando no acúmulo de CD4, retirados por Nef da membrana plasmática, em endossomos primários. A depleção de ?1A, outra subunidade de AP-1, acarretou na diminuição dos níveis celulares de ?2 e ?1, bem como, no comprometimento da eficiente degradação de CD4 por Nef. Além disso, foi possível observar que, ao perturbar a maquinaria ESCRT via super-expressão de HRS (uma subunidade do complexo ESCRT-0), ocorreu um acumulo de ?2 em endossomos dilatados contendo HRS-GFP, nos quais também detectou-se CD4 que foi internalizado por Nef. Em conjunto, os resultados indicam que ?2-adaptina é uma importante molécula para o direcionamento de CD4 por Nef para a via ESCRT/MVB, mostrando ser uma proteína relevante no sistema endo-lisossomal. Ademais, os resultados indicaram que as isoformas ?-adaptinas não só possuem funções distintas, mas também parecem compor complexos AP-1 com diferentes funções celulares, já que apenas a variante AP-1 contendo ?2, mas não ?1, participa da regulação negativa de CD4 por Nef. Estes estudos contribuem para o melhor entendimento dos mecanismos moleculares envolvidos na atividade de Nef, que poderão também ajudar na melhor compreensão da patogênese do HIV e da síndrome relacionada. Em adição, este trabalho contribui para o entendimento de processos fundamentais da regulação do tráfego de proteínas transmembrana no sistema endo-lisossomal.The Human Immunodeficiency Virus (HIV) is the etiologic agent of Acquired Immunodeficiency Syndrome (AIDS). AIDS is a disease which has a global distribution, and it is estimated that there are currently at least 36.9 million people infected with the virus. During the replication cycle, HIV promotes several changes in the physiology of the host cell to promote their survival and enhance replication. The fast progression of HIV-1 in humans and animal models is closely linked to the function of an accessory protein Nef. Among several actions of Nef, one is the most important is the down-regulation of proteins from the immune response, such as the CD4 receptor. It is known that this action causes CD4 degradation in lysosome, but the molecular mechanisms are still incompletely understood. Nef forms a tripartite complex with the cytosolic tail of the CD4 and adapter protein 2 (AP-2) in clathrin-coated vesicles, inducing CD4 internalization and lysosome degradation. Previous research has demonstrated that CD4 target to lysosomes by Nef involves targeting of this receptor to multivesicular bodies (MVBs) pathway by an atypical mechanism because, although not need charging ubiquitination, depends on the proteins from ESCRTs (Endosomal Sorting Complexes Required for Transport) machinery and the action of Alix, an accessory protein ESCRT machinery. It has been reported that Nef interacts with subunits of AP- 1, AP-2, AP-3 complexes and Nef does not appear to interact with AP-4 and AP-5 subunits. However, the role of Nef interaction with AP-1 or AP-3 in CD4 down-regulation is poorly understood. Furthermore, AP-1, AP-2 and AP-3 are potentially heterogeneous due to the existence of multiple subunits isoforms encoded by different genes. However, there are few studies to demonstrate if the different combinations of APs isoforms are form and if they have distinct functional properties. This study aim to identify and characterize cellular factors involved on CD4 down-modulation induced by Nef from HIV-1. More specifically, this study aimed to characterize the involvement of AP-1 complex in the down-regulation of CD4 by Nef HIV-1 through the functional study of the two isoforms of ?-adaptins, AP-1 subunits. By pull-down technique, we showed that Nef is able to interact with ?2. In addition, our data from immunoblots indicated that ?2- adaptin, not ?1-adaptin, is required in Nef-mediated targeting of CD4 to lysosomes and the ?2 participation in this process is conserved by Nef from different viral strains. Furthermore, by flow cytometry assay, ?2 depletion, but not ?1 depletion, compromises the reduction of surface CD4 levels induced by Nef. Immunofluorescence microscopy analysis also revealed that ?2 depletion impairs the redistribution of CD4 by Nef to juxtanuclear region, resulting in CD4 accumulation in primary endosomes. Knockdown of ?1A, another subunit of AP-1, resulted in decreased cellular levels of ?1 and ?2 and, compromising the efficient CD4 degradation by Nef. Moreover, upon artificially stabilizing ESCRT-I in early endosomes, via overexpression of HRS, internalized CD4 accumulates in enlarged HRS-GFP positive endosomes, where co-localize with ?2. Together, the results indicate that ?2-adaptin is a molecule that is essential for CD4 targeting by Nef to ESCRT/MVB pathway, being an important protein in the endo-lysosomal system. Furthermore, the results indicate that ?-adaptins isoforms not only have different functions, but also seem to compose AP-1 complex with distinct cell functions, and only the AP-1 variant comprising ?2, but not ?1, acts in the CD4 down-regulation induced by Nef. These studies contribute to a better understanding on the molecular mechanisms involved in Nef activities, which may also help to improve the understanding of the HIV pathogenesis and the related syndrome. In addition, this work contributes with the understanding of primordial process regulation on intracellular trafficking of transmembrane proteins.
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Hasbullah, Hasbullah. "Alleviating the negative effect of salinity on soil respiration by plant residue addition: effect of residue properties, mixing and amendment frequency." Thesis, 2015. http://hdl.handle.net/2440/102766.
Full textAbstract:
Salinity is a major constraint to crop production and also contributes to land degradation, particularly in arid and semiarid regions. Salinity has negative effects on soil microorganisms, reducing soil respiration, microbial biomass and microbial diversity. One of the main reasons for the negative impact of salinity is the low osmotic potential induced by high salt concentrations in the soil solution which reduces water uptake into cells and can cause water loss from cells. Some microorganisms can adapt to salinity by accumulation of osmolytes which is a significant metabolic burden. Rapidly decomposable plant residues contain high concentrations of easily available compounds which can be utilised by many soil microbes. Slowly decomposable residues on the other hand contain complex compounds which can only be utilised by few microbes, those capable of releasing specialised enzymes to break down these compounds. If salinity inhibits or kills some microbes, the decomposition of rapidly decomposable residues may be less affected than that of slowly decomposable residues because the loss of sensitive microbes can be compensated by a larger number of microbes with the former compared to the latter. If this is true, microbial activity after addition of slowly decomposable residues (high in lignin content and C/N ratio and low in water soluble carbon) should decrease more strongly with increasing salinity than after addition of rapidly decomposable residues. However, most previous studies on respiration in saline soils only used one or two types of plant residues (e.g. cereal or legume shoots). A further factor that may influence the impact of salinity on soil respiration is the frequency of residue addition. Frequent residue addition may provide soil microbes with a continuous supply of nutrients and therefore improve salinity tolerance compared to a single addition where easily available compounds are rapidly depleted. These two assumptions have not been systematically investigated.
The aim of this project was to investigate the effect of the chemical composition of added residues, mixing of residues and addition frequency on soil respiration and microbial biomass in soils with different salinity. Three studies were carried out to address the aims in non-saline soil and naturally saline soils with different salinity levels. The aim of the first study was to investigate the impact of salinity on respiration in soil amended with residues differing in chemical composition (lignin concentration, water soluble organic carbon and C/N ratio). Three incubation experiments were conducted in this study. In the first experiment various residue types (shoots of wheat, canola, saltbush and kikuyu, saw dust, eucalyptus leaves) differing in C/N ratio, lignin and water extractable organic carbon concentration, were applied at 2% w/w to a non-saline soil (EC₁﹕₅, 0.1 dS m⁻¹) and three naturally saline soils with EC₁﹕₅ 1, 2.5 and 3.3 dS m⁻¹. Cumulative respiration decreased with increasing salinity but the negative effect of salinity was different among residues. Compared to non-saline soil, respiration was decreased by 20% at EC₁﹕₅ 0.3 dS m⁻¹ when slowly decomposable residues (saw dust or canola shoots) were added, but at EC₁﹕₅ 4 dS m⁻¹ when amended with a rapidly decomposable residue (saltbush). In the second experiment, the influence of residue C/N ratio and lignin content on soil respiration in saline soils was investigated. Two residues (canola and saw dust) with high C/N ratios but different lignin content were used. The C/N ratio was adjusted to between 20 and 80 by adding ammonium sulfate. Increasing salinity had smaller impact on cumulative respiration after addition of residues with C/N ratio 20 or 40 compared to residues with higher C/N ratio. In the third experiment, the effect of the concentration of water-soluble organic C (WEOC) of the residues was determined. WEOC was partially removed by leaching from two residues with high WEOC content (eucalypt leaves and saltbush shoots). Partial WEOC removal decreased cumulative respiration in saline soil compared to the original residues, but increased the negative effect of salinity on respiration only with saltbush shoots. The second study was conducted using the four soils from the first study (EC₁﹕₅, 0.1, 1, 2.5 and 3.3 dS m⁻¹) to compare the impact of single and multiple additions of residues that differ in decomposability on the response of soil respiration to increasing salinity. Two residues with distinct decomposability were used; kikuyu with 19 C/N ratio (rapidly decomposable) and canola with 82 C/N ratio (slowly decomposable). Both residues were added once or 2-4 times (on days 0, 14, 28 and 42) with a total addition of 10 g C kg⁻¹ soil and incubated for 56 days. Compared to a single addition, repeated addition of the rapidly decomposable residue reduced the negative effect of salinity on cumulative respiration, but this was not the case with slowly decomposable residues. The third study was carried out to investigate the effect of the proportion of rapidly and slowly decomposable residues in a mixture on the impact of salinity on soil respiration. This study included two experiments with two residues differing in decomposability (slowly decomposable saw dust and rapidly decomposable kikuyu grass). In the first experiment, both residues were added alone and in mixtures with different ratios into four soils having EC₁﹕₅ 0.1, 1.0, 2.5 and 3.3 dS m⁻¹. The addition of 25% of rapidly decomposable residues in mixture with slowly decomposable residues was sufficient to decrease the negative impact of salinity on cumulative respiration compared to the slowly decomposable residue alone. In the second experiment, three soils were used (EC₁﹕₅ 0.1, 1.0 and 2.5 dS m⁻¹), residues were added once or 3 times (on days 0, 14 and 28) to achieve a total of 10 g C kg⁻¹ soil either with sawdust alone, kikuyu alone or both where final proportion of kikuyu was 25%, but the order in which the residues were applied differed The negative effect of salinity on cumulative respiration was smaller when the rapidly decomposable residue was added early, that is when the soil contained small amounts of slowly decomposable residues. Salinity reduced soil respiration to a greater extent in treatments where rapidly decomposable residue was added to soil containing larger amounts of slowly decomposable residues. It is concluded that rapidly decomposable residues can alleviate salinity stress to soil microbes even if they make up only a small proportion of the residues added. By promoting greater microbial activity in saline soils and providing nutrients, rapidly decomposable residues could also improve plant growth through increased nutrient availability.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Agriculture, Food and Wine, 2015.
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Yeh, Pin Wei, and 葉品維. "Shuffle-Mixing Random Number Generator with Circular Shift Addition Technique." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/89umg7.
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Ju, Shr-Liang, and 朱士亮. "Effect of Cu Addition on 316L Stainless Steel by Mixing TiC Strengthening Phase." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/79404531081446947089.
Full textAbstract:
碩士國立屏東科技大學
機械工程系所
100
Added appropriate amount of TiC powder to 316L stainless steel (the best amount to add was 2wt%) during the press molding of powder metallurgy (PM for short) as well as transferred the atmosphere control from H2 to 50%H2 plus 50%N2 at the moderate temperature when sintering(the wonderful atmosphere transferable temperature was 1200℃), and gained the conclusive result that the grain growth was under control, the phase was reinforced, the content of Nitrogen reached the maximum, and the most of the mechanical properties of 316L stainless steel were enhanced. On the other hand, also found the ductility and corrosion resistance of the matrix became lower for the reason that some chemical compound precipitated on the grain boundary bringing hard and brittle phases. Therefore, Cu is added in this new experiment in hope of improving the sintering property between 316L stainless steel and TiC, decreasing the hard and brittle phases and enhancing the ductility and corrosion resistance. Four groups of specimens are made for this experiment: specimen A(316L stainless steel+2 wt%TiC), specimen B(316L stainless steel+2 wt%TiC plated with Cu of 0.5wt%), specimen C(316L stainless steel+2 wt%TiC plated with Cu of 1.5wt%) and specimen D(316L stainless steel+2 wt%TiC plated with Cu of 3wt%). The experimental results show that there is hardly precipitation on the grain boundary due to the effect of copper, thus reaching the target of decreasing the hard and brittle phases. There is also apparent improvement in density, ductility &; corrosion resistance. The hardness, wear resistance and strength become slightly weaker as the amount of copper plated is raised but is still within the acceptable range.
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"Single and multiple addition to C60. A computational chemistry study." Universitat de Girona, 2003. http://www.tesisenxarxa.net/TDX-0225104-131052/.
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Lee, Yen-Fei, and 李彥霏. "Effects of flour type, mixing water content and gum addition on the properties of noodles." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/70078741846259440192.
Full textAbstract:
碩士靜宜大學
食品營養學系
89
The purpose of this study is to investigate the effects of the variety of wheat, the mixing water content, the milled fraction of flour, and the addition of gum on the properties of noodle. The noodles were mixed in reduced pressure condition (160-180mmHg). The rheological behaviors (storage modulus, G’ and loss modulus, G”) and the enthalpy of noodle during cooking were monitored as a function of varieties of wheat flour (Australian hard wheat, AHW; Canadian western red spring, CWRS; dark north spring, DNS and hard red winter, HRW), mixing water content (35, 37.5, and 40% mb), milled fractions of wheat flour (F-1 and F-2), and gums (Tamarind seed gum A and S type, Psyllium seed gum, Xanthan gum). The hardness, the tensile strength, and the tensile distance of re-cooked frozen cooked noodle made from the factors above-mentioned were compared. In terms of the effect of wheat variety of flour, the rheological behaviors (G’ and G”) of raw noodle made from the variety, AHW, are higher than CWRS and DNS. The storage modulus and loss modulus of raw noodle made from HRW were the lowest among the four varieties. After cooked, G’ and G” of noodle made from CWRS was the highest, while the noodle from HRW had the lowest values. The storage modulus and loss modulus of noodle made from AHW decreased rapidly during cooking, this indicated that the noodles made from AHW were more sensitive to cooking. According to the result of the enthalpy, the rate of calculated extent of gelatinization of noodles made from HRW was the rapidest. The hardness of the re-cooked frozen cooked noodle made from HRW was the most sensitive to decreasing with the cycles of freeze-thaw increasing, this indicated that the resistance to freeze-thaw treatment of the frozen cooked noodle made from HRW was the lowest. The first frozen treatment was the more important treatment to decrease the hardness of frozen cooked noodles than the cycles of freeze-thaw treatment. In terms of the effect of mixing water content, the raw noodles made with lower mixing water content showed lower G’ and G”. The G’ and G” of noodle made with 37.5 and 40% mixing water content were more stable than made with 35% during cooking. The hardness of frozen cooked noodle made with different mixing water content decreased with frozen storage time increasing. The frozen stability of noodle made with 35% mixing water content was less than 37.5 and 40%. In terms of the effect of milled fraction of flour, the raw noodles made from DNS F-2 flour showed higher G’ and G” than the raw noodles made from DNS F-1 flour. The wheat variety, HRW, showed the contrary result to DNS. The noodles made from F-1 flour showed higher G’ than the noodle made from F-2 flour, even the water contents of noodle after cooking were similar. Freeze-thaw treatment and frozen storage time affected the hardness and the tensile strength of frozen cooked noodle made from F-2 flour more than made from F-1 flour. Such results implied that the frozen stability of the noodle made from F-2 flour was worse than made from F-1 flour. In terms of the effect of gum addition, Xanthan gum addition promoted the stability of the noodles during cooking. Tamarind seed gum type A addition promoted the frozen stability.
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Chou, Cheng-Hsueh, and 周承學. "Process optimization of an aluminum etching mixing system with multiple quality characteristics." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/44044338447768603523.
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Lin, Chun-Min, and 林忠民. "A Numerical Study of Multiple Jets of Mixing in a Sequential Burner." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/89552752746981940843.
Full textAbstract:
碩士逢甲大學
機械工程學系
89
A numerical study is presented for the mixing with multiple jets into a sequential burner by using the equation turbulence model and the control-volume integration formula for finite difference and SIMPLEST algorithm to find more information of the various mixing configurations of the transverse jets. The mixing rate is increasing up for an opposite geometry of H/D=10 and S/D=6. On the same jets conditions (J≧40), the offset geometry has better mixing rate than the opposite geometry. For the staggered geometry at J≧20, the mixing rate is always higher than the opposite geometry. The optimum mixing location of the y-z plane is investigated in this paper. The staggered geometry could obtain a high mixing rate of 80﹪∼90﹪to burn on the y-z plane at X/D=0.5 as J≧40. For J=50, the mixing rate could reaches 70﹪on the y-z plane at X/D=0.25. From the numerical investigation, we can find the best mixing configuration and the cross-flow mixing conditions at the geometry of H/D=10 and S/D=6. It not only can reduce the burner size but also shows how the cross-flow development making the burner to have a long working time. Keywords: model, momentum flux ratio, mixing rate, sequential burner
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Jeganmohan, Masilamani, and 捷格默罕. "Palladium-Catalyzed Addition Reactions of Electrophiles and Nucleophiles into Carbon-Carbon Multiple Bonds." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/90664295131001883864.
Full textAbstract:
博士國立清華大學
化學系
93
The thesis delineates the palladium catalyzed addition reactions of electrophiles and nucleophiles into carbon-carbon multiple bonds. This thesis is divided into four chapters. First chapter explains the synthesis of 1,7-enyne derivatives, the second chapter describes synthesis of 1,6-enynes, 1,6-enallenes and 1,6-dienes, the third chapter deals with the synthesis of substituted 2-arylallylgermanes, cyclicallylgermanes and cyclicallylsilanes and chapter 4 explains (E)-vinylicsilanes having allylstannanes in brief way. Chapter 1 describes palladium catalyzed propargylallylation reactions of activated olefins. The three component addition reaction of allylic chlorides and allenylstannaes with activated olefins in the presence of palladium catalyst affords 1,7-enyne derivatives with high regio-, stereo and chemoselectivity in good to excellent yields. The reaction proceeds with various substituted activated olefins. Furthermore, the reaction was successfully extended to an activated dienes. A plausible mechanism based on ��1-allenyl ��3-allyl palladium intermediate is proposed to account for the catalytic three-component reaction. Chapter 2 demonstrates the addition reactions of allylalkynyl, allylallenyl and allylalkenyl to benzynes in the presence of palladium catalyst. The reactions of allylic chlorides and alkynylstannanes into benzynes in the presence of palladium catalyst gave various 1-allyl-2-alkynylbenzenes in excellent yield. The reaction proceeds with various substituted benzyne precursors, allylic chlorides and alkynyl, allenyl and alkenylstannanes. This method allows an efficient synthesis of various 1-allyl-2-alkynylbenzenes, 1-allyl-2-allenylbenzenes and 1-allyl-2-alkenylbenzenes in good to excellent yields. Furthermore, the utility of 1-allyl-2-alkynylbenzenes in organic synthesis were successfully demonstrated with the synthesis of multiple rings. A possible mechanism for the present catalytic reaction is proposed. Chapter 3 describes the synthesis of substituted 2-arylallylgermanes in a highly regio-, stereo- and chemoselective fashion involving a three-component assembly of allenes, aryl iodides and stannylgermane catalyzed by phosphine-free palladium complexes. The present catalytic reaction is highly regioselective in which aryl group and metal add to the middle and unsubstituted terminal carbon of the allene moiety, respectively. In addition, the reaction is highly stereoselective to give Z-isomer as an exclusive product. Furthermore, the catalytic reaction was successfully extended into partially intermolecular version to give cyclic metal reagents with excellent yields. The high chemoselectivity of the present reaction is due to a favorable SE2 cyclic pathway involved in transemetalation step. The mechanism involving a face-selective coordination of allenes is proposed to account for the high stereoselectivity. Chapter 4 explains a highly regio- and stereoselective silylstannation of allenes using phosphine free palladium complexes. The addition reaction of trimethy(tributylstannyl)silane with allenes in the presence of phosphine-free palladium catalyst provided (E)-vinylicsilane having allylstannane moieties in excellent yield. The vinylic silanes and allyl stannanes present in these products allow for a large variety of chemical modifications. The nature of the ligand on the palladium complexes has a tremendous influence on the regio- and stereochemistry of present reactions.
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Liu, Charng Hing, and 劉常興. "Addition of Acetylenees to Bicyclic Alkenes. Multiple Carbon- carbon Bond Formation Promated by palladium Complexes." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/28544260812987450500.
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Beyers, Frederik Johannes Conradie. "A Hilbert space approach to multiple recurrence in ergodic theory." Diss., 2004. http://hdl.handle.net/2263/30545.
Full textAbstract:
The use of Hilbert space theory became an important tool for ergodic theoreticians ever since John von Neumann proved the fundamental Mean Ergodic theorem in Hilbert space. Recurrence is one of the corner stones in the study of dynamical systems. In this dissertation some extended ideas besides those of the basic, well-known recurrence results are investigated. Hilbert space theory proves to be a very useful approach towards the solution of multiple recurrence problems in ergodic theory. Another very important use of Hilbert space theory became evident only relatively recently, when it was realized that non-commutative dynamical systems become accessible to the ergodic theorist through the important Gelfand-Naimark-Segal (GNS) representation of C*-algebras as Hilbert spaces. Through this construction we are enabled to invoke the rich catalogue of Hilbert space ergodic results to approach the more general, and usually more involved, non-commutative extensions of classical ergodic-theoretical results. In order to make this text self-contained, the basic, standard, ergodic-theoretical results are included in this text. In many instances Hilbert space counterparts of these basic results are also stated and proved. Chapters 1 and 2 are devoted to the introduction of these basic ergodic-theoretical results such as an introduction to the idea of measure-theoretic dynamical systems, citing some basic examples, Poincairé’s recurrence, the ergodic theorems of Von Neumann and Birkhoff, ergodicity, mixing and weakly mixing. In Chapter 2 several rudimentary results, which are the basic tools used in proofs, are also given. In Chapter 3 we show how a Hilbert space result, i.e. a variant of a result by Van der Corput for uniformly distributed sequences modulo 1, is used to simplify the proofs of some multiple recurrence problems. First we use it to simplify and clarify the proof of a multiple recurrence result by Furstenberg, and also to extend that result to a more general case, using the same Van der Corput lemma. This may be considered the main result of this thesis, since it supplies an original proof of this result. The Van der Corput lemma helps to simplify many of the tedious terms that are found in Furstenberg’s proof. In Chapter 4 we list and discuss a few important results where classical (commutative) ergodic results were extended to the non-commutative case. As stated before, these extensions are mainly due to the accessibility of Hilbert space theory through the GNS construction. The main result in this section is a result proved by Niculescu, Ströh and Zsidó, which is proved here using a similar Van der Corput lemma as in the commutative case. Although we prove a special case of the theorem by Niculescu, Ströh and Zsidó, the same method (Van der Corput) can be used to prove the generalized result. Copyright 2004, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. Please cite as follows: Beters, FJC 2004, A Hilbert space approach to multiple recurrence in ergodic theory, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://upetd.up.ac.za/thesis/available/etd-02222006-104936 / >Dissertation (MSc (Applied Mathematics))--University of Pretoria, 2007.
Mathematics and Applied Mathematics
unrestricted
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Yang, Ting-Yi, and 楊庭懿. "Investigation on Sintering and Electrical Conductivity of Ceria-based Materials by Addition of Multiple Metal Oxides." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/pn46b6.
Full textAbstract:
碩士國立臺灣大學
材料科學與工程學研究所
107
Ceria-based electrolyte materials are synthesized by an EDTA-citric acid method. Two samples, Ce0.9Sm0.1O2 (ST00) and Ce0.9Sm0.09Fe0.005Mn0.005O2 (S9HH) are prepared and sintered to single cubic fluorite structure and still kept within solution limit. The microstructure and electrical properties are analyzed, showing S9HH having >99% theoretical density (T.D.) observed by SEM after sintered at 1250 ℃ for 5 hr, and suitable for an electrolyte of solid oxide fuel cell. Bulk electrical conductivity of S9HH and ST00 is a liner relationship to the reverse of the temperature (1/T). The bulk electrical conductivity of S9HH samples is 7.15*10-2 S•cm-1 higher than that of ST00 samples 2.60*10-2 S•cm-1 at 800 ℃. Both of the activation energy of ceria-based materials are around 1.10-1.20 eV, indicating the same conductivity mechanism by oxygen vacancy/ion exchange and diffusion. After an aging treatment at 650 ℃ for a holding time of 500 h, the electrical conductivity of S9HH reduces to 3.11*10-2 S•cm-1, but still higher than that of ST00 1.60*10-2 S•cm-1 at 800 ℃. The electrical conductivity degradation in long-term aging is because of the formation of continues Sm-rich fluorite sub-micro grains.
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ZHUANG, SHU-HAO, and 莊書豪. "Kinetic theory approach of the multiple plane jets turbulent mixing, combustion and HF chemical laser analysis." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/44002686814203450808.
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Pao-Min, Tseng, and 曾保閔. "Computerized multiple-choice and constructed response items the effectiveness of cognitive diagnosis- Elementary fraction addition and subtraction unit." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/16712316358095813719.
Full textAbstract:
碩士國立臺中教育大學
教育測驗統計研究所
100
ABSTRACT Cognitive diagnostic testing is very important at a teaching scene. And whether testing results can represent students’ true abilities is even more important. Currently, most computer diagnostic tests are composed of mainly multiple-choice questions. However, students may guess correct answers, influencing accuracy of tests. This study designed two test papers with the “score adding and subtracting” section. One test paper contains all multiple-choice questions and the other contains constructed-response questions. Also an automatic analysis mechanism for constructed-response questions was developed to automatically analyzing testing results to reduce teachers’ burdens of reading and correcting students’ test papers. The DINA and DINO models were applied to perform analyses on the data from testing. Some improvement was made regarding the issue of influences of guessing and carelessness of multiple-choice questions. And the accuracy of cognitive concept and error type estimations was increased. Then through different test paper generation methods, the 5 constructed-response questions were categorized into 6 methods, including superordinate concept, subordinate concept, most single item concept, least single item concept, most wrong answers for a single item, and least wrong answers for a single item. The multiple-choice questions were transformed into constructed-response questions in order to improve analysis accuracy. The final goal was to create a best test paper with accuracy and time efficiency. The research findings include: 1. When the study designed the constructed-response questions and the diagnostic model testing, it was found that there was a wrong answer type different from multiple-choice questions in the sample, meaning this diagnostic testing could diagnose students’ diversified abilities. 2. The accuracy of the constructed-response question automatic analysis model developed by this study to diagnose wrong answer types was averagely 92.53%, meaning the performance of this testing diagnostic model was outstanding. 3. This study applied the DINA and DINO models to perform estimation and was able to efficiently increase the accuracy of computer diagnoses. 4. The test paper with the best performance was test paper #5. The accuracy was improved from 77.39% to 81.36%.
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Chi-Te, Wu, and 吳啟得. "Computerized Multiple Choice Items and Performance Assessment for the Fifth Grade Math "Different Denominator Fraction Addition and Subtraction," Unit." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/86165924084336449907.
Full textAbstract:
碩士亞洲大學
資訊工程學系碩士在職專班
99
The study of fifth grade to "cross-denominator fraction addition and subtraction" unit for the scope of the study, according to the teaching objectives, sub-skills, the type of error, so as to Bayesian inference network as a tool to establish a set of Bayesian network to computer-based diagnostic tests national minority subjects, the diagnosis of students' error types, provide teaching reference. The results are as follows: First analysis of "cross-denominator fraction addition and subtraction, "the teaching materials, the establishment of the concept of proposition from proposition based on the concept of a computerized diagnostic test, sampling by using Bayesian network as a post-analysis tools, inference and sub-types of errors the students skills. The results are as follows: 1. The self of the fifth grade of elementary school mathematics "different denominator fraction addition and subtraction,"unit test questions, the test of Cronbach's α value of 0.737, with questions of this study showed good reliability. 2. Students of computer-based diagnostic expert identification of the type of error and the correct type of error rates were 95.3333%, 95.3333%, 93%, 89%, construction problems of diagnosis the average correct response rate of 93.1667%. 3 Four models of sub-skills to identify the type of error rate and pattern of the overall average recognition rate were 90%, display mode helps to enhance the recognition rate.
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HsinChen and 陳昕. "Quantification of Catechol Estrogen Modification on Serum Proteins by Multiple Reaction Monitoring and Standard Addition Using Liquid Chromatography-Mass Spectrometry." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/72ffhu.
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Clemens, Karen E. "Along-coast variations of Oregon beach-sand compositions produced by the mixing of sediments from multiple sources under a transgressing sea." Thesis, 1987. http://hdl.handle.net/1957/27779.
Full textAbstract:
Heavy mineral compositions of sands from Oregon beaches,
rivers and sea cliffs have been determined in order to examine the
causes of marked along-coast variations in the beach-sand
mineralogy. The study area extends southward from the Columbia
River to the Coquille River in southern Oregon. The heavy-mineral
compositions were determined by standard microscopic
identification with additional verification by X-ray diffraction
analyses. Initially the beach-sand samples were collected as single
grab samples from the mid-beachface, but significant selective
sorting of the important heavy minerals prevented reasonable
interpretations of the results. Factor analysis of multiple samples
from the same beach yielded distinct factors which correspond with
known mineral sorting patterns. The effects of local sorting were
reduced by the subsequent use of large composite samples,
permitting interpretations of along-coast variations in sand
compositions. Four principal beach-sand sources are identified by
factor analysis: the Columbia River on the north, a Coastal Range
volcanic source, sands from the Umpqua River on the south-Oregon
coast, and a metamorphic source from the Klamath Mountains of
southern Oregon and northern California. The end members identified
by factor analysis of the beach sands correspond closely to
river-source compositions, the proportions in a specific beach-sand
sample depending on its north to south location with respect to those
sources. During lowered sea levels of the Late Pleistocene, the
Columbia River supplied sand which was dispersed both to the north
and south, its content decreasing southward as it mixed with sands
from other sources. The distributions of minerals originating in the
Klamath Mountains indicate that the net littoral drift was to the
north during lowered sea levels. With a rise in sea level the
longshore movement of sand was interrupted by headlands such that
the Columbia River presently supplies beach sand southward only to
the first headland, Tillamook Head. At that headland there is a
marked change in mineralogy and in grain rounding with angular,
recently-supplied sands to the north and rounded sands to the south.
The results of this study indicate that the present-day central
Oregon coast Consists of a series of beaches separated by headlands,
the beach-sand compositions in part being relict, reflecting the
along-coast mixing at lower sea levels and subsequent isolation by
onshore migration of the beaches under the Holocene sea-level transgression. This pattern of relict compositions has been modified
during the past several thousand years by some addition of sand to
the beaches by sea-cliff erosion and contributions from the rivers
draining the nearby Coastal Range.Graduation date: 1987
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Mohebbi, Hamid Reza. "Parametric Interaction in Josephson Junction Circuits and Transmission Lines." Thesis, 2011. http://hdl.handle.net/10012/5973.
Full textAbstract:
This research investigates the realization of parametric amplification in superconducting circuits and structures where nonlinearity is provided by Josephson junction (JJ) elements. We aim to develop a systematic analysis over JJ-based devices toward design of novel traveling-wave Josephson parametric amplifiers (TW-JPA). Chapters of this thesis fall into three categories: lumped JPA, superconducting periodic structures and discrete Josephson transmission lines (DJTL).
The unbiased Josephson junction (JJ) is a nonlinear element suitable for parametric amplification through a four-photon process. Two circuit topologies are introduced to capture the unique property of the JJ in order to efficiently mix signal, pump and idler signals for the purpose of signal amplification. Closed-form expressions are derived for gain characteristics, bandwidth determination, noise properties and impedance for this kind of parametric power amplifier. The concept of negative resistance in the gain formulation is observed. A design process is also introduced to find the regimes of operation for gain achievement. Two regimes of operation, oscillation and amplification, are highlighted and distinguished in the result section. Optimization of the circuits to enhance the bandwidth is also carried out.
Moving toward TW-JPA, the second part is devoted to modelling the linear wave propagation in a periodic superconducting structure. We derive closed-form equations for dispersion and s-parameters of infinite and finite periodic structures, respectively. Band gap formation is highlighted and its potential applications in the design of passive filters and resonators are discussed. The superconducting structures are fabricated using YBCO and measured, illustrating a good correlation with the numerical results.
A novel superconducting Transmission Line (TL), which is periodically loaded by Josephson junctions (JJ) and assisted by open stubs, is proposed as a platform to realize a traveling-wave parametric device. Using the TL model, this structure is modeled by a system of nonlinear partial differential equations (PDE) with a driving source and mixed-boundary conditions at the input and output terminals, respectively. This model successfully emulates parametric and nonlinear microwave propagation when long-wave approximation is applicable. The influence of dispersion to sustain three non-degenerate phased-locked waves through the TL is highlighted.
A rigorous and robust Finite Difference Time Domain (FDTD) solver based on the explicit Lax-Wendroff and implicit Crank-Nicolson schemes has been developed to investigate the device responses under various excitations. Linearization of the wave equation, under small-amplitude assumption, dispersion and impedance analysis is performed to explore more aspects of the device for the purpose of efficient design of a traveling-wave parametric amplifier.
Knowing all microwave characteristics and identifying different regimes of operation, which include impedance properties, cut-off propagation, dispersive behaviour and shock-wave formation, we exploit perturbation theory accompanied by the method of multiple scale to derive the three nonlinear coupled amplitude equations to describe the parametric interaction. A graphical technique is suggested to find three waves on the dispersion diagram satisfying the phase-matching conditions. Both cases of perfect phase-matching and slight mismatching are addressed in this work. The incorporation of two numerical techniques, spectral method in space and multistep Adams-Bashforth in time domain, is employed to monitor the unilateral gain, superior stability and bandwidth of this structure. Two types of functionality, mixing and amplification, with their requirements are described. These properties make this structure desirable for applications ranging from superconducting optoelectronics to dispersive readout of superconducting qubits where high sensitivity and ultra-low noise operation is required.