Intrusion Detection systems are now an essential component in the overall network and data security arsenal. With the rapid advancement in the network technologies including higher bandwidths and ease of connectivity of wireless and mobile devices, the focus of intrusion detection has shifted from simple signature matching approaches to detecting attacks based on analyzing contextual information which may be specific to individual networks and applications. As a result, anomaly and hybrid intrusion detection approaches have gained significance. However, present anomaly and hybrid detection approaches suffer from three major setbacks; limited attack detection coverage, large number of false alarms and inefficiency in operation. / In this thesis, we address these three issues by introducing efficient intrusion detection frameworks and models which are effective in detecting a wide variety of attacks and which result in very few false alarms. Additionally, using our approach, attacks can not only be accurately detected but can also be identified which helps to initiate effective intrusion response mechanisms in real-time. Experimental results performed on the benchmark KDD 1999 data set and two additional data sets collected locally confirm that layered conditional random fields are particularly well suited to detect attacks at the network level and user session modeling using conditional random fields can effectively detect attacks at the application level. / We first introduce the layered framework with conditional random fields as the core intrusion detector. Layered conditional random field can be used to build scalable and efficient network intrusion detection systems which are highly accurate in attack detection. We show that our systems can operate either at the network level or at the application level and perform better than other well known approaches for intrusion detection. Experimental results further demonstrate that our system is robust to noise in training data and handles noise better than other systems such as the decision trees and the naive Bayes. We then introduce our unified logging framework for audit data collection and perform user session modeling using conditional random fields to build real-time application intrusion detection systems. We demonstrate that our system can effectively detect attacks even when they are disguised within normal events in a single user session. Using our user session modeling approach based on conditional random fields also results in early attack detection. This is desirable since intrusion response mechanisms can be initiated in real-time thereby minimizing the impact of an attack.

Master of Engineering (Research) / Multiple antenna systems are an appealing candidate for emerging fourth-generation wireless networks due to its potential to exploit space diversity for increasing conveyed throughput without wasting bandwidth and power resources. Particularly, layered space-time architecture (LST) proposed by Foschini, is a technique to achieve a significant fraction of the theoretical capacity with a reasonable implementation complexity. There has been a great deal of challenges in the detection of space-time signal; especially to design a low-complexity detector, which can efficiently remove multi-layer interference and approach the interference free bound. The application of iterative principle to joint detection and decoding has been a promising approach. It has been shown that, the iterative receiver with parallel interference canceller (PIC) has a low linear complexity and near interference free performance. Furthermore, it is widely accepted that the performance of digital communication systems can be considerably improved once the channel state information (CSI) is used to optimize the transmit signal. In this thesis, the problem of the design of a power allocation strategy in LST architecture to simultaneously optimize coding, diversity and weighting gains is addressed. A more practical scenario is also considered by assuming imperfect CSI at the receiver. The effect of channel estimation errors in LST architecture with an iterative PIC receiver is investigated. It is shown that imperfect channel estimation at an LST receiver results in erroneous decision statistics at the very first iteration and this error propagates to the subsequent iterations, which ultimately leads to severe degradation of the overall performance. We design a transmit power allocation policy to take into account the imperfection in the channel estimation process. The transmit power of various layers is optimized through minimization of the average bit error rate (BER) of the LST architecture with a low complexity iterative PIC detector. At the receiver, the PIC detector performs both interference regeneration and cancellation simultaneously for all layers. A convolutional code is used as the constituent code. The iterative decoding principle is applied to pass the a posteriori probability estimates between the detector and decoders. The decoder is based on the maximum a posteriori (MAP) algorithms. A closed-form optimal solution for power allocation in terms of the minimum BER is obtained. In order to validate the effectiveness of the proposed schemes, substantial simulation results are provided.

Cette thèse a pour objet l'étude des oxydes lamellaires NaxVO2. Différentes phases ont été obtenues qui diffèrent dans l'empilement des feuillets [VO2] : O3-NaVO2, P'3-Na0.56VO2 et P2-Na0.73VO2. Ces trois matériaux ont fait l'objet d'une étude électrochimique en batterie sodium couplée à la diffraction des rayons X in situ afin de comprendre les transitions structurales qui se produisent en fonction de la composition. Une superstructure apparait à Na1/2VO2 pour les trois types d'empilements. Cette composition a pu être obtenue par synthèse potentiostatique. La caractérisation structurale montre qu’à cette composition les trois polytypes présentent une mise en ordre Na+/lacune et suggère la présence de clusters d'ions vanadium. De cette organisation particulière résulte un comportement inhabituel des propriétés physiques. Ce travail démontre les corrélations électroniques importantes dans cette famille de matériaux et ouvre la voie à de futures études en physique et chimie du solide. / This thesis is about the study of the lamellar oxides NaxVO2. Several phases have been obtained with different stacking of the [VO2] sheets: O3-NaVO2, P’3-Na0.56VO2 and P2-Na0.73VO2. These three materials have been the subject of an electrochemical study in sodium batteries coupled with in situ X-ray diffraction in order to understand the structural transitions taking place as a function of the composition. A superstructure appears at Na1/2VO2 for the three stackings. This composition has been obtained by potentiostatic synthesis. The structural characterization shows that at this composition the three polytypes present a Na+/vacancy ordering and suggests the presence of clusters of vanadium ions. An unusual behaviour of the physical properties is observed as a result of this peculiar organization. This work demonstrates the important electronic correlations in this family of materials and paves the path to future studies in solid-state chemistry and physics.

Novel solutions to offset thermal degradation of polyamide-6 (PA-6) and organoclay (organically modified layered silicates) nanocomposites during melt compounding have been investigated. In this research, a novel chain extender (Joncryl ADR 3400) has been used to improve thermal stability of PA-6 and PA- 6/organoclay nanocomposites during melt compounding. The materials were compounded using a linear twin extruder and various laboratory scale mixers. The effects of organoclay and chain extender were studied using both processing methods. In order to replicate large scale production used in industry, a comprehensive plan of experimental work was carried out under different processing conditions (extrusion temperature and screw speed), organoclay and chain extender loading using a linear twin screw extruder. Rheology, mechanical and thermal properties were analysed and selected samples were also characterised by TEM and FTIR. Process induced degradation of PA-6 during the melt compounding was found to have significant influence on the rheological and mechanical properties. Rheological and mechanical characterisation clearly showed showed that incorporation of the chain extender minimised thermal degradation of PA-6 and nanocomposites during melt processing. Visual analysis of selected nanocomposites using TEM confirmed that chain extender increased the dispersion of nanoclays in the PA- 6 matrix. The crystallinity of the PA-6 was slightly affected by addition of organoclay and chain extender. The samples obtained by linear twin screw extrusion showed higher rheological properties than the samples from laboratory scale mixers suggesting better mixing and less thermal degradation during extrusion.

Conventional yttria stabilized zirconia (YSZ) are widely used in the gas turbine to protect the substrate material from high temperature. But the common YSZ top coatings have limitations at higher temperature (above 1200 ℃) due to significant phase transformation and intensified sintering effect. Among the list of pyrochlores, gadolinium zirconate offer very attractive properties like low thermal conductivity, high thermal expansion coefficient and CMAS resistance. However, a lower fracture toughness than YSZ and tendency to react with alumina (thermal grown oxide) can lead to lower lifetime. Therefore, multi-layered thermal barrier coating approach was attempted and compared with single layer system. Single layer (YSZ) was processed by suspension plasma spraying (SPS). Double layer coating system comprising of YSZ as the bottom ceramic layer and gadolinium zir-conate as the top ceramic coat was processed by SPS. Also, a triple layer coating system with denser gadolinium zirconate on top of double layer system, was sprayed. Denser gado-linium zirchonate acts as the sealing layer and arrest the CMAS penetration. Isothermal oxidation performance of the sprayed coating systems including bare substrate and sub-strate with bond coat were investigated for a time period of 10hr, 50hr and 100hr at 1150℃ in air environment. Weight gain was observed in all the systems investigated. Microstruc-tural analysis was carried out using optical microscopy, SEM/EDS. Phase analysis was done using X-ray diffraction (XRD). Porosity measurement was made by water impregna-tion method. It was observed that multi-layered thermal barrier coating systems of YSZ/GZ and YSZ/GZ/GZ(dense) showed lower weight gain and TGO thickness than the single layer YSZ for all exposure time (10hr, 50hr & 100hr). The triple layer system had lower weight gain and TGO thickness compared to double layer system due to lower po-rosity content. Also, from the porosity measurement data, it could be seen that sintering effect is more dominant at 10 hr. of oxidation for all the coatings systems.

abstract: Understanding the temperature structure of protoplanetary disks (PPDs) is paramount to modeling disk evolution and future planet formation. PPDs around T Tauri stars have two primary heating sources, protostellar irradiation, which depends on the flaring of the disk, and accretional heating as viscous coupling between annuli dissipate energy. I have written a "1.5-D" radiative transfer code to calculate disk temperatures assuming hydrostatic and radiative equilibrium. The model solves for the temperature at all locations simultaneously using Rybicki's method, converges rapidly at high optical depth, and retains full frequency dependence. The likely cause of accretional heating in PPDs is the magnetorotational instability (MRI), which acts where gas ionization is sufficiently high for gas to couple to the magnetic field. This will occur in surface layers of the disk, leaving the interior portions of the disk inactive ("dead zone"). I calculate temperatures in PPDs undergoing such "layered accretion." Since the accretional heating is concentrated far from the midplane, temperatures in the disk's interior are lower than in PPDs modeled with vertically uniform accretion. The method is used to study for the first time disks evolving via the magnetorotational instability, which operates primarily in surface layers. I find that temperatures in layered accretion disks do not significantly differ from those of "passive disks," where no accretional heating exists. Emergent spectra are insensitive to active layer thickness, making it difficult to observationally identify disks undergoing layered vs. uniform accretion. I also calculate the ionization chemistry in PPDs, using an ionization network including multiple charge states of dust grains. Combined with a criterion for the onset of the MRI, I calculate where the MRI can be initiated and the extent of dead zones in PPDs. After accounting for feedback between temperature and active layer thickness, I find the surface density of the actively accreting layers falls rapidly with distance from the protostar, leading to a net outward flow of mass from ~0.1 to 3 AU. The clearing out of the innermost zones is possibly consistent with the observed behavior of recently discovered "transition disks." / Dissertation/Thesis / Ph.D. Physics 2012

L'utilisation de l'équation de Dirac/Weyl conduit à une simplification conceptuelle dans une description de la structure de la bande dans les solides à faible échelle d'énergie. En particulier, les excitations d'électrons-trous peuvent être considérées comme analogues au cas relativiste tel que conductivité optique linéaire, le suppression de backscattering ou la manifestation des arcs de Fermi et la chiralité des particules. En outre, la phase semi-métallique est également un élément crucial pour la classification des matériaux. La taille de le gap est affectée qualitativement par le type de dispersion d'énergie par un croisement continu des bandes linéaires à paraboliques. Cela peut être compris comme une limite classique ou ultra-relativiste du mouvement d'une particule massive.La spectroscopie infrarouge de la transformation de Fourier est une technique unique pour étudier les excitations optiques dans une large gamme d'énergies et représente en combinaison avec le champ magnétique élevé un outil puissant pour sondage de la structure électronique et surmonte le principal obstacle des systèmes sans gap qui est un dopage fort en raison de désordre structurel.La première partie du travail est consacrée à l'arséniure de cadmium, où nous élaborons une approche de distinction qualitative entre les systèmes Dirac et Kane qui ont été utilisés pour prouver sur la base de la réponse magnéto-optique observée la réalisation du modèle Kane presque sans gap avec une similitude frappante avec HgCdTe, en contradiction avec l'existence de cônes purement Dirac. La magnéto-réflectivité dans un champ magnétique à champ élevé la résonance cyclotron caractéristiques par un radical-B dépendance avec un comportement particulier dans la limite quantique. En revanche, la magnéto-transmission montrait des transitions de niveau Landau qui doit être interprétées que comme un type plat-à-cône afin de préserver une cohérence totale du modèle. Les cônes de Dirac prédits par la théorie sont susceptibles de coexister dans le modèle de Kane sous la forme d'une sous-structure décrite par le modèle de Bodnar qui se rapproche de la structure cristalline complexe par une simple cellule antifluorite qui permet d'utiliser la théorie du k.p classique.Dans la deuxième partie, nous nous concentrons sur le bismuth comme isolant topologique 3D archétype. Nous étudions une condition particulière obéie pour le BHZ-hamiltonien qui apporte des propriétés intriguantes comme une relation inhabituelle de spin gap et la résonance du cyclotron, l'épinglage spécifique entre les fancharts des sous-groupes Landau ou les g-facteurs compensés dans les bandes de conduction et de valence. Les mesures de photoluminescence ont montré une émission directgap, ce qui donne un nouvel aperçu de la structure largement acceptée à partir des données ARPES, où la “chameau structure” de la bande de valence doit être expliquée dans le confinement de surface et le point de Dirac de l'état de surface doit être repositionné par rapport aux bandes en bulk. La réponse magnéto-optique peut être pleinement expliquée dans une image classique du paramagnétisme de Pauli comme un simple effet d'occupation. Un tel comportement se manifeste dans la transmission en tant que fractionnement progressif du bord d'absorption interbande avec une saturation successive due à la polarisation spin partielle ou totale des électrons. Le dichroïsme relatif entraîne également une forte rotation de Faraday linéaire décrite par un modèle simple de la constante Verdet qui ne dépend pas sur le niveau de Fermi. / The use of the Dirac/Weyl equation leads to a conceptual simplification in a description of the band structure in solids at low energy scales. In particular, electron-hole excitations can be regarded as an analogue to the relativistic case with several expected phenomena to be observed in the condensed systems such as a suppressed back-scattering, linear optical conductivity or the manifestation of the Fermi arcs and particle's chirality. Moreover, the semimetallic phase also symbolizes a boundary between the trivial and topological insulators and thus play a crucial role for the material classification. The size of the gap qualitatively affects the type of the energy dispersion by a continuous crossover from the linear to parabolic bands. This fact can be easily understood as a classical or ultra-relativistic limit of the motion of a free massive particle.Infrared Fourier transform spectroscopy is a unique technique for studying optical excitations in a wide range of energies and it represents in combination with the high magnetic field a powerful tool for probing electronic structure and overcomes the main obstacle of the gapless systems that is a strong doping due to the structural disorder.The first part of the work is devoted to cadmium arsenide, where we elaborate an approach to qualitatively distinguish between the Dirac and Kane systems that was used to prove on the basis of the observed magneto-optical response the realization of the nearly gapless Kane model with a striking similarity to HgCdTe, contradicting the existence of purely Dirac cones. The magneto-reflectivity revealed a strong splitting of the plasma edge that turns into the cyclotron resonance characteristic by a squareroot-of-B dependence in the high magnetic field with a particular behaviour in the quantum limit independent on the initial Fermi level. In contrast, the magneto-transmission revealed interband Landau level transitions that could be only interpreted as a flat-to-cone type in order to preserve a full consistency of the model. The Dirac cones predicted by theory are feasible to coexist within the Kane model in the form of a substructure described by the Bodnar model that approximates the complex crystal structure by a simple antifluorite cell, which allows to use the conventional k.p-theory.In the second part, we focus on bismuth selenide entitled as an archetypal 3D topological insulator. We study a peculiar condition fulfilled for the BHZ-hamiltonian that brings intriguing properties such as an unusual relation of the spin gap and cyclotron resonance, the specific pinning between fancharts of Landau subsets or the compensated g-factors of the conduction and valence bands. The photoluminescence measurements showed a direct-gap emission, that gives a new insight to the widely accepted structure from ARPES data, where the declared camel-back structure of the valence band needs to be explained within the surface confinement and the Dirac point of the surface state should be repositioned with respect to the bulk bands. The magneto-optical response can be fully explained in a classical picture of the Pauli paramagnetism as a purely occupational effect. Such behaviour is evinced in the transmission as a gradual splitting of the interband absorption edge with a successive saturation due to the partial or total spin polarization of electrons. The related dichroism drives also a strong linear Faraday rotation described by a simple model of the Verdet constant that depends only on the Fermi level.

Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2016-09-05T17:55:13Z No. of bitstreams: 1 Dissertação (Fredson Santos Guimarães).pdf: 3047547 bytes, checksum: ab4e997db06f03d33d60e156a51abba1 (MD5) / Approved for entry into archive by Vanessa Reis (vanessa.jamile@ufba.br) on 2016-09-06T10:42:39Z (GMT) No. of bitstreams: 1 Dissertação (Fredson Santos Guimarães).pdf: 3047547 bytes, checksum: ab4e997db06f03d33d60e156a51abba1 (MD5) / Made available in DSpace on 2016-09-06T10:42:39Z (GMT). No. of bitstreams: 1 Dissertação (Fredson Santos Guimarães).pdf: 3047547 bytes, checksum: ab4e997db06f03d33d60e156a51abba1 (MD5) / CAPES / A hidrotalcita é um hidroxicarbonato de magnésio e alumínio que consiste em camadas do tipo brucita e ocorre na natureza como lâminas contorcidas e folheadas e/ou massa fibrosa. Quando Mg2+ e Al3+ são trocados completamente ou parcialmente com M2+ (M = Co, Ni, Cu, Zn, Fe) e M3+ (Cr e Fe) respectivamente, materiais cristalinos com estrutura hidrotalcita podem ser obtidos. A fórmula geral do LDH é [M2+1-xM3+x(OH)2]+(An-x/n)yH2O, onde M2+ e M3+ são respectivamente cátions metálicos di e trivalentes. Neste trabalho, pigmentos híbridos derivados de hidróxidos duplos lamelares (LDHs) com o corante vermelho congo (diazo) e o corante negro de eriocromo T (azo) foram preparados por dois métodos diferentes: i) adsorção de uma solução de corante sobre MgAl-LDH, previamente preparado por coprecipitação em pH = 11 empregando Na2CO3; ii) automontagem por coprecipitação em pH = 11 dos íons Mg2+ e Al3+ com NaOH em uma solução contendo o corante (self assembly). Análises de DRX mostraram que o espaçamento basal (d003) da matriz MgAl-LDH dos pigmentos preparados por adsorção não sofreu variação, sugerindo que as moléculas dos corantes estão adsorvidas na superfície externa dos cristais de LDH enquanto que os preparados pelo método self assembly revelaram que parte dos corantes azo encontra-se intercalada. Análises TG/DTG mostraram que as temperaturas de decomposição oxidativa dos corantes foram deslocadas para valores superiores, sugerindo que as moléculas do corante são termicamente mais estáveis na estrutura do LDH. As análises de microscopia eletrônica de varredura corroboraram os resultados de DRX, mostrando que os pigmentos preparados pelos métodos da adsorção e self assembly tem morfologia lamelar, típica de compostos tipo hidrotalcita ratificando os resultados das análises de DRX. Quando submetidos a testes de estabilidade em solventes de diferentes polaridades (água, etanol e acetonitrila), os pigmentos híbridos mostraram-se mais estáveis quando o solvente foi a água. Pode-se atribuir essa estabilidade a diferenças estruturais mais significativas na estrutura dos corantes com a molécula da água quando comparado com outros solventes. / Hydrotalcite is a hydroxycarbonate of magnesium and aluminium and occurs in nature in foliated and contorced plates and/or fibrous masses. When Mg2+. and Al3+. are replaced wholly or partially with M2+. (M.Co, Ni, Cu, Zn, Fe) and M3+. (M.Cr, Fe), respectively, crystalline materials with the hydrotalcite can be obtained. The general formula of LDH is [M2+1-xM3+x(OH)2]+(An-x/n)yH2O, where M2+ and M3+ are respectively metallic cations divalents and trivalents. In this work, hybrid pigments, derived from layered double hydroxides (LDHs) with the diazo dye congo red and azo dye eriochrome black t , were prepared using two different methods: i) adsorption of aqueous solution of congo red onto MgAl-LDH, previously prepared by coprecipitation at pH = 11, using Na2CO3; and ii) coprecipitation of Mg2+and Al3+ in a congo red containing solution, at pH = 11, using NaOH as precipitating agent (self assembly); iii) adsorption of aqueous solution of eriochrome black t onto MgAl-LDH, previously prepared by coprecipitation at pH = 11, using Na2CO3; and ii) coprecipitation of Mg2+and Al3+ in a eriochrome black t containing solution, at pH = 11, using NaOH as precipitating agent (self assembly). X-ray diffraction show in the samples prepared by adsorption no change in the basal space (d003) was observed, suggesting that intercalation of the anionic dye did not occur significantly. In the sample prepared by self-assembly, it was observed the formation of a LDH containing at least part of the dye in the interlayer region. In the thermogravimetric analysis TGA show the temperature of oxidation decomposition of the dyes occurs at a temperature higher, indicating that the thermal stability of pigment is enhanced by intercalation in the layered host. Scanning electron micrographs analysis shows the morphology of the hybrid pigments prepared by adsorption and self assembly show morphology characteristic of hydrotalcite materials which was observed for all samples. When to subdue the stability tests in solvents of polarity different (water, ethanol , acetonitrile), the hybrids pigments show higher stabily when the solvents is water.

108 f. / Submitted by Ana Hilda Fonseca (anahilda@ufba.br) on 2013-04-08T14:18:11Z No. of bitstreams: 1 Dissertação - Camila Santana Carriço.pdf: 3281348 bytes, checksum: a3b9881e9a61204bb28727d3345e0e1e (MD5) / Approved for entry into archive by Ana Hilda Fonseca(anahilda@ufba.br) on 2013-06-06T15:31:43Z (GMT) No. of bitstreams: 1 Dissertação - Camila Santana Carriço.pdf: 3281348 bytes, checksum: a3b9881e9a61204bb28727d3345e0e1e (MD5) / Made available in DSpace on 2013-06-06T15:31:43Z (GMT). No. of bitstreams: 1 Dissertação - Camila Santana Carriço.pdf: 3281348 bytes, checksum: a3b9881e9a61204bb28727d3345e0e1e (MD5) Previous issue date: 2012 / CAPES / O aproveitamento do glicerol excedente pela conversão catalítica a produtos de maior valor agregado vem sendo bastante estudado no sentido de dar um destino mais nobre a este coproduto, valorizando a cadeia produtiva do biodiesel. Dentre os processos de conversão catalítica do glicerol destaca-se a sua desidratação a acroleína, um produto de grande interesse da Química Fina, que pode ser utilizada como matéria-prima para a produção de ácido acrílico, polímeros superabsorventes produtos farmacêuticos, entre outros. Os zeólitos são catalisadores bastante ativos para a desidratação do glicerol a acroleína, devido às suas propriedades ácidas e texturais, mas sua principal limitação é a rápida desativação por formação de coque, como resultado da acidez excessiva e dos pequenos diâmetros de poros encontrados nestes materiais. Uma alternativa promissora é o uso de materiais derivados de zeólitos de precursores lamelares, que permitem ajuste das propriedades ácidas e texturais através de processos de pilarização e exfoliação. Neste trabalho, o precursor lamelar de estrutura MWW foi sintetizado nas razões molares SiO2/Al2O3 = 30, 50 e 80, e convertidos ao zeólito MCM-22 por calcinação, ao derivado pilarizado com SiO2, conhecido como MCM-36 e ao derivado exfoliado, denominado ITQ-2. As amostras foram caracterizadas por DRX, FTIR, TG/DTG, análise textural, MEV e TPD-NH3. Os materiais foram avaliados na reação de desidratação do glicerol à acroleína em fase gasosa e os parâmetros reacionais temperatura, tempo de contato (W/F) e concentração de glicerol foram ajustados com o zeólito MCM-22 na razão molar SiO2/Al2O3 = 30. As condições que favoreceram maiores conversões e seletividades foram empregadas para avaliar os materiais MCM-36 e ITQ-2. Os difratogramas de raios-X comprovaram que a síntese dos materiais foi bem sucedida, apresentando os picos característicos da topologia MWW. A análise textural mostra uma diminuição do volume de microporos e um aumento do volume de mesoporos, consistente com os processos de pilarização e exfoliação do precursor lamelar de estrutura MWW. O processo de exfoliação aumenta a acessibilidade aos sítios ácidos, enquanto a pilarização provoca o bloqueio dos sítios ácidos de natureza zeolítica e criação de novos sítios ácidos devidos aos pilares de SiO2. O melhor desempenho do MCM-36 na conversão de glicerol pode ser associado a sua dupla porosidade, a qual não permite que os canais/sítios ativos sejam obstruídos pela formação de resíduos carbonáceos, e consequentemente, permite que este material seja ativo por mais tempo, no entanto apresenta baixa seletividade a acroleína e formação de subprodutos gasosos. O ITQ-2 mostrou-se altamente seletivo a acroleína, resultado da maior densidade de sítios ácidos e maior acessibilidade aos sítios zeolíticos presentes nas semicavidades superficiais das lamelas. Em todos os materiais o aumento da razão molar SiO2/Al2O3 resulta num decréscimo da conversão do glicerol e da seletividade à acroleína. O principal mecanismo de desativação destes materiais é a formação de coque, que pode ser eliminado por tratamento em atmosfera oxidante a 500°C. O ITQ-2 apresentou uma boa recuperação em três ciclos reacionais / Salvador

A participação de líquidos magmáticos extraídos do manto, registrados sob a forma de intrusões dioríticas, gabroicas e de rochas máficas-ultramáficas, tem sido apontada como uma componente determinante na geração de magmas intermediários a ácidos, em ambientes orogênicos a pós-colisionais. Neste contexto, a colocação de líquidos basálticos hidratados na base da crosta também é considerada um importante marcador petrogenético, já que além de fornecer calor, pode ainda contribuir com líquidos residuais fracionados, essenciais à geração de magmas evoluídos. Além disso, magmas pouco diferenciados podem igualmente ascender e atingir níveis superiores da crosta, interagindo com câmaras magmáticas silicosas. Assim, estas rochas acabam por registrar tanto os processos de extração e transporte de magmas do manto, resultando na acresção vertical de material à crosta, quanto os processos de interação entre esses dois componentes. Na porção sudeste do Cinturão Dom Feliciano (RS), constituída majoritariamente por granitoides, ocorrem rochas dioríticas e gabroicas de extensão reduzida (1 a 7 km) e caráter dominantemente básico, na região compreendida entre os municípios de Pinheiro Machado e Pedro Osório. Nesta dissertação, por meio da caracterização geológica, mineralógica, petrográfica e geoquímica destas rochas, propõe-se a separação de duas associações principais. A “Associação I” (AI) engloba os corpos do Passo da Fabiana, Passo da Olaria, Arroio Santa Fé e Desvio Herval, constituindo-se por rochas gabroicas comumente cumuladas, por vezes estratificadas A “Associação II” (AII), diorítica a gabroica, compreende rochas isótropas a localmente foliadas, nas ocorrências do Alto Alegre, Passo dos Machados e Campo Bonito. As duas associações são subalcalinas, com afinidade cálcio-alcalina médio-K (AI) e médio a alto-K (AII), exibindo altos teores de alumina (Al2O3 > 17%), mesmo para os termos não cumulados. Maiores valores de CaO e Mg# na AI, e de álcalis, P2O5, Zr, Nb, Y, e total de ETR na AII, bem como padrões distintos de ETR, referendam a separação das associações. O controle no posicionamento das rochas básicas por descontinuidades litosféricas é sugerido pelas assinaturas magnéticas, que teriam possibilitado a ascensão e colocação destes magmas em níveis superiores da crosta. Como processos petrogenéticos, sugere-se a participação de líquidos derivados do manto em câmaras magmáticas supracrustais, seja como pulsos precursores do magmatismo associado aos granitoides, ou por eventos de reabastecimento destes reservatórios, como predominantes na AI. Já na AII, rica em anfibólio, processos envolvendo a colocação e evolução de magmas do manto nas DCHZ (deep crustal hot zones), originando líquidos hidratados, parecem ser mais expressivos. / The participation of mantle-derived melts, recorded as dioritic, gabbroic and mafic-ultramafic rocks, has been identified as a determinant component in the generation of intermediate to acid magmas, in orogenic to post-collisional settings. In this context, the emplacement of hydrous basaltic liquids at the base of the crust is also considered an important petrogenetic marker, not only providing heat, but also producing residual fractionated liquids, essential to the generation of evolved magmas. Furthermore, less differentiated magmas can also ascend and reach upper crustal levels, interacting with silicic magma chambers. Therefore, this rocks record both magma extraction and transport processes from the mantle, resulting in vertical material accretion to the crust, as well as the interaction between these two components. In the southeastern portion of Dom Feliciano Belt (RS), which is composed mainly by granitoids, minor dioritic and gabbroic rocks occur (1 to 7 km), with predominantly basic character, in the region between Pinheiro Machado and Pedro Osório. This thesis presents geological, mineralogical, petrographic and geochemical characterization of these rocks, proposing thus the separation of two main associations. The "Association I" (AI) comprises the bodies Passo da Fabiana, Passo do Olaria, Arroio Santa Fé and Desvio Herval, and is composed by gabbroic rocks, commonly as cumulates, sometimes in layered intrusions The "Association II" (AII), dioritic to gabbroic, comprises isotropic to locally foliated rocks, in the occurrences of Alto Alegre, Passo dos Machados and Campo Bonito. Both associations are subalkaline, with medium-K (AI) and medium to high-K (AII) calc-alkaline affinity, showing high-alumina contents (Al2O3 > 17%), even for the non-cumulated terms. Higher CaO and Mg# values in AI, and alkalis, P2O5, Zr, Nb, Y, and total REE in AII, as well as distinct REE patterns, support the proposed associations. The control on the emplacement of the basic rocks by lithospheric discontinuities is suggested by magnetic signatures, which would have enabled the ascent and emplacement of these magmas to upper crustal levels. As petrogenetic processes, the participation of mantle-derived liquids in supracrustal magma chambers is suggested, either as precursor pulses of the magmatism associated with the granitoids, or by replenishment events in these reservoirs, as prevalent in AI. In the AII, amphibole-rich, processes involving the emplacement and evolution of mantle-derived magmas in DCHZ (deep crustal hot zones), originating hydrous liquids, seems to be more expressive.