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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
201

Degradacao e estabilidade radiolitica do policarbonato

ARAUJO, ELMO S. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:37:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:30Z (GMT). No. of bitstreams: 1 02032.pdf: 2356043 bytes, checksum: a593207617f1975d8e81afa9455b3bff (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
202

Sintese do sesquinitreto de uranio e seu uso como catalisador da reacao de termodecomposicao da amonia

ROCHA, SORAYA M.R. da 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:40:52Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:28Z (GMT). No. of bitstreams: 1 02950.pdf: 4952382 bytes, checksum: 1dddfe6ca71077632e2bdf2d56006ba7 (MD5) / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
203

Degradacao e estabilidade radiolitica do policarbonato

ARAUJO, ELMO S. de 09 October 2014 (has links)
Made available in DSpace on 2014-10-09T12:37:24Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:30Z (GMT). No. of bitstreams: 1 02032.pdf: 2356043 bytes, checksum: a593207617f1975d8e81afa9455b3bff (MD5) / Tese (Doutoramento) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
204

\"Óxidos do tipo Perovskitas para reações de decomposição direta de NO e redução de NO com CO\" / \"Reduction of NO by CO and direct decomposition of NO on perovskite-type oxide\"

Eurico Yuji Tanabe 20 April 2006 (has links)
Uma tecnologia importante para reduzir a quantidade de poluentes atmosféricos lançados na atmosfera, é a utilização de catalisadores, que convertem os gases altamente poluentes como o NO, para outros gases inofensivos ao meio ambiente. Neste trabalho, os óxidos do tipo perovskitas La2CuO4, LaNiO3, LaMnO3, La1,4Sr0,6CuO4, La0,7Sr0,3NiO3 e La0,7Sr0,3MnO3 foram preparados através do método da co-precipitação, caracterizados por difração de raios-X, redução a temperatura programada, fisissorção de nitrogênio e análise química, e, posteriormente avaliados frente as reações de redução de NO com CO, e decomposição direta de NO. Ambas as reações foram testadas nas temperaturas de 400oC e 500oC e o tempo de reação foi de 7 à 10 horas. Através dos ensaios catalíticos verificou-se que o catalisador La2CuO4 apresentou a maior atividade para a reação de redução, e quando substituiu-se parcialmente o lantânio pelo estrôncio, houve uma melhora significativa para todos os catalisadores. As análises de DRX indicaram que, mesmo após os ensaios catalíticos, a estrutura cristalina dos catalisadores foi preservada. / A important technology to reduce the atmospheric pollution is the use of catalysts, to transform high pollutant as NO in other inoffensive gases to the environment. In this work, the perovskite oxides La2CuO4, LaNiO3, LaMnO3, La1,4Sr0,6CuO4, La0,7Sr0,3NiO3 e La0,7Sr0,3MnO3 were prepared through co-precipitation method and characterized by X-ray diffraction and temperature programmed reduction, nitrogen physsisorption and subsequent valued on the reduction of NO by CO and the direct decomposition of NO. These reaction were tested at 400oC and 500oC temperatures and times of reaction between 7 and 10 hours. Through the catalytic tests the La2CuO4 catalyst shown the best activity to the reduce reaction, and when the La is partially substituted by strontium all the catalyst showed a better significant for all the catalysts. The XRD analysis shown that the catalytic structure of the catalysts were preserved after the catalytic test yet.
205

[en] CONSIDERATIONS ON THE DECOMPOSITION OF LINEAR PROGRAMS / [pt] ASPECTOS DA DECOMPOSIÇÃO DE PROGRAMAS LINEARES

PAULO CESAR MARQUES VIEIRA 18 September 2009 (has links)
[pt] Neste trabalho é feito um estudo teórico das três estratégias de coordenação que são usadas nos algoritmos de decomposição em programação matemática: Preços, quotas e mista. São apresentadas as respectivas condições de coordenabilidade com uma discussão sobre o problema da descentralização das decisões no caso de programas lineares. O objetivo é mostrar que a coordenação mista é a alternativa mais viável para se obter a descentralização das decisões quando os subproblemas são lineares. / [en] This work presents a theoretical discussion about the three coordination mechanisms used on decomposition algorithms in mathematical programming: price-directive, resource-directive and mixed mechanisms. The coordenability conditions are developed around the decentralization of the decisions problem in linear programs. The goal is to suggest the mixed mechanism as the best way to get the decentralization whem the subproblems are linear programs.
206

Amines in Olefin Metathesis: Ligands and Poisons

Ireland, Benjamin January 2016 (has links)
Olefin metathesis is a powerful tool for assembly of carbon-carbon bonds. Amines and related N-donors are problematic functional groups in Ru-catalyzed olefin metathesis - a well- documented, but poorly understood problem. The first part of this thesis focuses on amine-induced deactivation pathways; two of which are described in depth. Alkylidene abstraction, a previously unknown reaction for nitrogen nucleophiles, was observed for smaller and less Bronsted-basic amines. Deprotonation of the metallacyclobutane intermediate formed during catalysis is prominent for highly Bronsted basic or sterically bulky N-donors. Monosubstituted (and, by extension unsubstituted) metallacyclobutanes are particularly vulnerable to deprotonation. For each pathway, the fate of the alkylidene Ru=CHR functional group proved key in determining the nature of deactivation. Both pathways have been detected during catalysis, as evidenced by formation of diagnostic amine (RCH2NR2’) or substituted propene products. A combination of quantitative NMR and GC-MS analysis was used to identify these species on loss of the Ru-alkylidene functional group. The second part of this thesis focuses on incorporating amines into catalyst design – an under-utilized strategy in the context of Ru-catalyzed olefin metathesis. A modified Grubbs-type catalyst was developed featuring a bulky, relatively non-basic biaryldiamine ligand. Metathesis activity for this catalyst was comparable, and in some cases superior to the most widely-used homogeneous catalysts currently available. Several new, related Ru-benzylidenes were also prepared and fully characterized in conjunction with the mechanistic studies described above. Progress toward development of N-anion-containing metathesis catalysts is also discussed. Synthesis of Ru-hydride complexes originally intended for this purpose allowed for a fundamental study of the coordination chemistry and reductive elimination chemistry of the NPh2– anion.
207

Regression test selection by exclusion

Ngah, Amir January 2012 (has links)
This thesis addresses the research in the area of regression testing. Software systems change and evolve over time. Each time a system is changed regression tests have to be run to validate these changes. An important issue in regression testing is how to minimise reuse the existing test cases of original program for modied program. One of the techniques to tackle this issue is called regression test selection technique. The aim of this research is to signicantly reduce the number of test cases that need to be run after changes have been made. Specically, this thesis focuses on developing a model for regression test selection using the decomposition slicing technique. Decomposition slicing provides a technique that is capable of identifying the unchanged parts of the system. The model of regression test selection based on decomposition slicing and exclusion of test cases was developed in this thesis. The model is called Regression Test Selection by Exclusion (ReTSE) and has four main phases. They are Program Analysis, Comparison, Exclusion and Optimisation phases. The validity of the ReTSE model is explored through the application of a number of case studies. The case studies tackle all types of modication such as change, delete and add statements. The case studies have covered a single and combination types of modication at a time. The application of the proposed model has shown that signicant reductions in the number of test cases can be achieved. The evaluation of the model based on an existing framework and comparison with another model also has shown promising results. The case studies have limited themselves to relatively small programs and the next step is to apply the model to larger systems with more complex changes to ascertain if it scales up. While some parts of the model have been automated tools will be required for the rest when carrying out the larger case studies.
208

Sensibilité d'un écoulement de rouleau compressé et des variations cycle à cycle associées à des paramètres de remplissage moteur / Sensitivity of the compressed tumble motion and of the cycle to cycle variations to engine’s air filling parameters.

Cao, Yujun 17 December 2014 (has links)
Ce travail concerne l’étude expérimentale de la sensibilité de l’écoulement du moteur et de ses variations cycle à cycle (VCC) à trois variations des conditions aux limitesliée à l’optimisation du remplissage moteur. Dans la configuration standard, l’écoulement tridimensionnel de rouleau (« tumble ») est décrit pendant les phases d’admission et de compression.Un phasage plus précoce de la loi de levée d’admission augmente le débit de masse aux soupapes et amplifie les fluctuations dès le début de l’admission. L’intensité du rouleau est beaucoup plus faible à phase mi-compression. L’énergie fluctuante au point mort haut est plus faible. Une course rallongée du moteur conduit, en fin de compression, à un basculement de l’écoulement moyen et à une évolution très différente des vitesses fluctuantes,due au confinement différent vue par l’aérodynamique du moteur. Enfin, la modification des conduits d’admission entraîne une variation de l’intensité et une structuration fondamentalement différente de l’écoulement. En outre, pour décrire le transfert vers la turbulence,deux méthodologies de classification des structures de l’écoulement en groupe par corrélation spatiale, puis par « clustering » sont adaptées. L’analyse statistique du contenu des différents groupes et des transitions entre groupes permet de montrer que les VCC sont associées à différentes trajectoires dans l’espace des groupes. Des statistiques conditionnelles sont calculées pour analyser les données de chaque groupe et permettent de définir une décomposition triple. Ces caractérisations plus précises des VCC sont très générales et applicables à des grandes bases de données expérimentales ou numériques. / This experimental work concerns a sensitivity study of the in-cylinder flow in aspark-ignition engine and of the cycle to cycle variations (CCV) by comparing three variationsof boundary conditions related to the optimisation of air filling conditions. In the reference case, the three dimensional tumble flow is characterized during the intake and compression phases. A earlier intake cam phase increases the mass flow rate at inlet valves and amplifiesthe fluctuations immediately after the start of intake phase. The tumble ratio is much lowerat mid-compression phase. The fluctuating energy at top dead center is reduced. A longerengine stroke leads, at the end of compression phase, to a shift of mean flow and to a verydistinct evolution of the fluctuating velocity, due to the different confinement from the pointof view of the engine internal flow. Finally, the modification of intake duct design changes theflow intensity and reorganizes in depth the flow structure. Moreover, to describe the transfer into turbulence, two methodologies of classification in groups of flow structures, by spatial correlation then by clustering, are proposed. A phase-averaged analysis of the statistics of group content and inter-group transitions shows that CCV can be associated with different sets of trajectories during the second half of the compression phase. The conditional statistics are computed to analyse the data in each group, which leads to a triple decomposition. It is important to point out that this more accurate evaluation of CCV is applicable to very large sets of experimental or numerical data.
209

Développement d'une approche innovante de modélisation de la cinétique de décomposition thermique des matériaux solides en espaces confinés sous-ventilés. Application aux incendies en tunnel / Development of an Innovative Modelling Approach of the Thermal Decomposition Kinetics of Solid Mateirals in Confined Under Ventilated Environments. Application to Tunnel Fires

Hermouet, Fabien 18 December 2015 (has links)
Les incendies de tunnels sont des phénomènes violents, à l’évolution rapide qui engendrent la plupart du temps des dommages importants aux personnes et aux biens. La sécurité incendie dans les tunnels routiers est basée sur l’utilisation de modèles empiriques très simplifiés de description de l’évolution de la cinétique de développement de l’incendie. Ces modèles ne prennent cependant pas en compte le type de combustible impliqués dans le phénomène, tels que les polymères constitutifs des enveloppes des véhicules routiers, ni leurs réactivité en phase solide (décomposition thermique). Dans l’optique de faire évoluer la description de l’incendie en fonction des conditions ambiantes caractéristiques d’un tunnel, un modèle prédictif de la décomposition thermique des matériaux a été développé. Ce modèle mathématique a été construit sur la base d’une approche expérimentale à petite échelle faisant intervenir le dispositif du cône calorimètre à atmosphère contrôlée couplé à un spectromètre infrarouge à transformée de Fourrier. Trois matériaux ont fait l’objet d’une étude approfondie de leur décomposition thermique, en fonction de deux paramètres clés influençant la décomposition des solides lors d’un incendie de tunnel : la concentration d’oxygène ambiante et l’éclairement énergétique imposé aux matériaux. Les résultats obtenus pour les trois matériaux choisis (une mousse Polyisocyanurate, un Ethylène Propylène Diène Monomère et un Acrylonitrile Butadiène Styrène) ont été utilisés pour la construction de régressions polynomiales multifactorielles, méthode également connue sous le nom de méthodologie des surfaces de réponses.Le modèle permet de définir la réponse de la cinétique de décomposition (variable expliquée) et son évolution, en fonction de la concentration d’oxygène locale et de l’éclairement énergétique imposé à la surface d’un matériau (variables explicatives). La comparaison des résultats numériques et expérimentaux a alors montré la pertinence de ce type d’approche / Tunnel fires are severe phenomenon whose evolution, usually very fast, can lead to important damages to persons and properties. Tunnel fire safety is based on the use of empirical models, very simplified that describes the evolution of the fire kinetic. Nevertheless, these models does not take into account neither the type of material that are involved in the phenomenon, such as constitutive polymers of road vehicles nor their reactivity in solid phase (thermal decomposition). In order to provide an evolution of the fire description, function of the conditions usually encountered in a tunnel, a predictive model aiming to describe materials’ thermal decomposition has been developed. This mathematical model has been established on the basis of an experimental approach, at small scale, using the Controlled Atmosphere Cone Calorimeter coupled to a Fourier Transform Infrared Spectrometer. The thermal degradation of three different materials (Polyisocyanurate foam, Acrylonitrile Butadiene Styrene and Ethylene Propylene Diene Monomer) has been thoroughly assessed function of key parameters that drives the decomposition process during fire: oxygen concentration and heat flux imposed to the materials. Obtained results for the three materials have then been used to construct multifactorial polynomial regressions, using the methodology known as surface response methodology. The model allows defining the response of the decomposition kinetics (explained variable), function of both the oxygen concentration and the heat flux received at the surface of the material (explanatory variable). Comparisons between numerical and experimental obtained results show the relevance of this approach.
210

The thermal decomposition of silver oxide

Herley, Patrick James January 1960 (has links)
[From Introduction]. The thermal decomposition of solids is characterized by the formation and growth of nuclei at sites on the surface of the solid or within the crystal lattice. Such nuclear formation is favoured by disorganisation of the crystal either by mechanical damage, or by the presence of impurities. Disorganisation results in positions which have a high thermodynamic instability. The nuclei are likely to be formed initially at the corners and the edges of the crystal since these are more prone to damage. Careful handling and storage in vacuo often leads to a large reduction in their number, while deliberate scratching of the surface facilitates their production. The number of potential sites for nuclear formation is also increased by pre-irradiation with ultra-violet light, though there are indications that a different type of nucleus may be produced. Nucleation can be facilitated by pre-irradiation with electrons, neutrons, X-rays, gamma-rays and atomic particles. The nature of the nuclei is not always clearly defined, but it is generally accepted that they are composed of solid reaction products e.g. in the decomposition of barium azide and silver oxalate, nuclei of metallic barium and silver, respectively, are formed.

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