[pt] Escoamentos bifásicos no regime de golfadas são caracterizados pela alternância de pacotes de líquido e grandes bolhas de gás na tubulação, sendo associados a altas perdas de carga, além de trazer uma indesejada intermitência aos escoamentos. O desenvolvimento do regime de golfadas em tubulações horizontais se dá a partir do escoamento estratificado em decorrência de dois fatores: do crescimento natural de pequenas perturbações (por um mecanismo de instabilidade do tipo Kelvin-Helmholtz) ou devido à acumulação de líquido causada por mudanças de inclinação no perfil do duto. O presente trabalho consiste da simulação numérica do surgimento das golfadas em ambas as situações descritas acima, assim como do subseqüente desenvolvimento do escoamento neste padrão para um regime estatisticamente permanente. A previsão do escoamento é obtida utilizando-se uma formulação unidimensional baseada no Modelo de Dois Fluidos. Parâmetros médios das golfadas (comprimento, velocidade e freqüência) são comparados com estudos numéricos e experimentais da literatura, obtendo-se uma concordância bastante satisfatória, especialmente dada a simplicidade de uma formulação unidimensional. / [en] Slug flow is a two-phase flow pattern which is characterized by the periodic presence of packs of liquid and long bubbles in the tube, associated with high pressure-drops and an often undesired intermittency in the system. The development of the slug pattern in horizontal pipes is caused by two reasons: the natural growth of small disturbancies at the interface (by a Kelvin-Helmholtz instability mechanism) or the liquid accumulation at valleys of hilly terrain pipelines with sections of different inclinations. The present work consists of the numerical simulation of the onset of slugging in both situations, as well as the subsequent development of statistically steady slug flow in the pipe. The prediction of the flow is obtained through a one- dimensional formulation based on the Two-Fluid Model. Averaged slug parameters (length, velocity and frequency) are compared with previous numerical studies and experimental correlations avaiable in the literature, and a very satisfactrory agreement is obtained, specially given the simplicity of a one dimensional formulation.

A nacionalização dos hidrocarbonetos pelo presidente boliviano Evo Morales, em maio de 2006, provocou a mais séria crise na política externa brasileira durante o primeiro mandato presidencial de Lula. A decisão prejudicou os interesses da Petrobras, na época a maior empresa instalada na Bolívia, com presença em todos os ramos da atividade petroleira. O conflito foi amplificado pela existência de uma relação de interdependência entre os dois países com base no gasoduto de 3.150 quilômetros, que transporta quase a metade do gás natural consumido pela indústria no Brasil. Com a nacionalização sem expropriação, segundo a fórmula adotada por Morales, as empresas estrangeiras foram autorizadas a permanecer na Bolívia, mas tiveram de renegociar seus contratos, aceitando a ampliação da receita fiscal (government take) obtida pelo governo a partir da produção petroleira. Essa decisão do governo boliviano expôs as contradições da política do Brasil para a América do Sul. Lula, pressionado pela oposição conservadora, intercedeu em defesa dos lucros da Petrobras, mas ao mesmo tempo reconheceu a nacionalização como expressão do direito soberano da Bolívia em legislar sobre seus próprios recursos naturais, abstendo-se de represálias. A tese explora a ambigüidade do comportamento regional do Brasil, que tenta conciliar um discurso de solidariedade em relação aos vizinhos menos desenvolvidos com uma política de expansão das empresas brasileiras e de proteção dos investimentos no exterior. O conflito em torno do gás boliviano abalou os planos brasileiros de liderança regional sul-americana e tornou mais difícil a integração energética, uma das prioridades da política externa de Lula. / The nationalization of hidrocarbons by Bolivian president Evo Morales, in May 2006, has provocated the most serious crisis in Brazilian foreign policy during Lulas first presidential term. The decision has damaged the interests of Petrobras, then the biggest corporation in Bolivia, operating in all branches of oil activities. The conflict was amplified by the interdependent relationship between the two countries through a 3.150 kilometers gasoduct, which carries almost half the natural gas consumed by Brazilian industry. By nationalization without expropriation, according to Morales formula, foreign oil corporations were allowed to stay in Bolivia, but were forced to renegociate their contracts, increasing the government take on oil and gas production. Bolivian governments decision has exposed the contradictions of Brazilian foreign policy towards its South American neighbors. Lula, under pressure from conservative opposition, has acted on behalf of Petrobras profits, but at the same time he recognized Bolivian right to set the rules on its own natural resources, and has not taken any reprisal. The thesis explores the ambiguities of Brazilian regional behavior, trying to conciliate a discourse of solidarity to lesser developed neighbors with the international expansion of Brazilian companies and investment protection abroad. The conflict about Bolivian gas has shattered Brazilian plans for regional leadership and turned more difficult energy regional integration, one of the priorities of Lulas foreign policy.

The pipelines used to transport oil and gas from the wellheads to the distribution and refining sites can be subjected to high levels of pressure and temperature. Under such conditions, the pipelines tend to expand, but, if the expansion is inhibited, a significant compressive axial force can arise, leading to their buckling, which can occur in the horizontal or vertical plane. In this context, the objective of the present work is to analyze the upheaval buckling of pipelines, considering the internal pressure to which they are subjected during the transportation of oil and gas as its only triggering. Using the concept of effective axial force, it aims at discussing two different approaches for considering the internal pressure in buckling problems: distributed loads dependent on pipeline curvature and equivalent compressive axial forces with follower and non-follower characteristics. It also discusses the influence of using static or dynamic analysis for such approaches. Concerning the upheaval buckling itself, the work intends to analyze and compare the influence of the soil imperfection amplitudes to the influence of the friction between the pipeline and the ground in the critical loads and in the post-buckling configurations of the pipeline. Besides theoretical research, the objectives are achieved through the development of various numerical models, since geometrically-simple models, without the consideration of the interaction between the pipeline and the ground, until more complex models, with the use of contact models to detect the ground and its imperfections. The models are developed in Giraffe (Generic Interface Readily Accessible for Finite Elements) using geometrically-exact finite element models of beams, undergoing large displacements and finite rotations. Through the research, it is concluded that there is an equivalence between the application of the internal pressure as a distributed load dependent on pipeline curvature and the application of the internal pressure as a follower compressive axial force. Besides this, it is demonstrated that the type of the analysis (static or dynamic) depends on the nature of the physical system analyzed. With the aid of results presented in terms of internal pressure, classical results about the influence of the imperfection amplitudes and of the friction between the pipeline and the ground in buckling are confirmed. It is also showed that the imperfection amplitudes analyzed play a more important role in the post-buckling configurations of the pipeline than the friction. / Os dutos utilizados para transportar petróleo e gás natural das reservas até os locais de distribuição e refino podem estar submetidos a elevados níveis de pressão e temperatura. Sob tais condições, os dutos tendem a se expandir, porém, se a expansão é inibida, uma força axial de compressão significativa pode surgir nos dutos, ocasionando a flambagem lateral ou vertical dos mesmos. Dentro desse contexto, o objetivo do presente trabalho é analisar a flambagem vertical de dutos, considerando a pressão interna à qual eles estão submetidos durante o transporte de petróleo e gás natural como o único parâmetro desencadeador da flambagem. Usando o conceito de força axial efetiva, o trabalho objetiva discutir duas abordagens diferentes para considerar a pressão interna nos problemas de flambagem: carregamentos distribuídos dependentes da curvatura do duto e forças axiais de compressão equivalentes à pressão com caráter seguidor e não seguidor. O trabalho também discute a influência de usar a análise estática ou dinâmica para analisar essas abordagens de carregamento. Com relação à flambagem vertical propriamente dita, o trabalho pretende analisar e comparar a influência das amplitudes das imperfeições presentes no solo com a influência do atrito entre o duto e o solo nas cargas críticas e nas configuração pós-críticas do duto. Além de pesquisa teórica, os objetivos são atingidos através do desenvolvimento de vários modelos numéricos, desde modelos geometricamente simples, sem a consideração da interação entre o duto e o solo, até modelos mais complexos, com o uso de modelos de contato para detectar o solo e suas imperfeições. Os modelos são desenvolvidos no Giraffe (Generic Interface Readily Accessible for Finite Elements) usando elementos finitos geometricamente exatos de viga, sujeitos a grandes deslocamentos e rotações finitas. Através da pesquisa, conclui-se que existe uma equivalência entre a aplicação da pressão interna como um carregamento distribuído dependente da curvatura do duto e a aplicação da pressão interna como uma força axial de compressão seguidora. Além disso, demonstra-se que o tipo de análise (estática e dinâmica) depende da natureza do sistema físico analisado. Com a ajuda de resultados apresentados em termos de pressão interna, os resultados clássicos sobre a influência das amplitudes das imperfeições e do atrito entre o duto e o solo são confirmados. Também é mostrado que as amplitudes das imperfeições analisadas desempenham uma maior influência nas configurações pós-críticas do duto do que o atrito.

Os aços para tubos API 5L X80 são aços de alta resistência e baixa liga (ARBL) usados na fabricação de tubos para o transporte de gás e petróleo conduzidos através de dutos. Os tubos API 5L X80 se caracterizam por terem excelentes propriedades mecânicas como resistência à tração, tenacidade, ductilidade e resistência à corrosão, além de boa soldabilidade. Estes tubos trazem muitos benefícios como, por exemplo, o fator econômico já que ao ter boa resistência mecânica estes tubos podem ser fabricados com espessuras de parede menores. Estas reduções nas espessuras diminuem os custos de transporte, construção, soldagem e instalação. Além disso, estes tubos podem ser fabricados com grandes diâmetros, permitindo o transporte de grandes quantidades de fluidos a elevadas pressões e vazões. A tenacidade confere ao material a propriedade de ser resistente à fratura frágil, uma vez que estes tubos em sua maioria trabalham em condições ambientais severas. O objetivo deste trabalho é simular fisicamente e estudar as propriedades mecânicas de regiões da zona afetada pelo calor (ZAC) produzidas por diferentes ciclos térmicos, que ocorrem quando o tubo é fabricado e o duto montado. A ideia foi estudar a ZAC produzida no tubo fabricado pelo processo UOE (solda longitudinal) e a solda feita no campo quando o tubo é montado (solda circunferencial) além da ZAC na intersecção entre a soldagem longitudinal e circunferencial. Foram usinados corpos-de-prova nas orientações L-T e T-L e com o cordão de solda longitudinal do tubo no centro. Estes corpos-de-prova foram submetidos a quatro ciclos térmicos únicos com temperaturas máximas de 650, 800, 950 e 1300 °C e ciclos térmicos multipasse 950-800 e 950-800- 650 °C. Estes corpos-de-prova foram submetidos a diferentes ensaios e caracterizações. Foram feitos ensaios de impacto a 0 °C, as superfícies fraturadas foram analisadas no MEV e mediu-se a expansão lateral produzida pelo ensaio de impacto. Mediu-se a dureza da microestrutura por meio do ensaio Vickers com 300g de carga. A microestrutura da ZAC foi caracterizada por microscopia óptica, com ataque convencional e ataque colorido Klemm, e microscopia eletrônica de varredura. Metalografia quantitativa foi usada para obter a quantidade de perlita na matriz dos corpos-de-prova. A trajetória da fratura na microestrutura dos corpos-de-prova simulados, provocada pelo ensaio Charpy, foi analisada com microscopia óptica e eletrônica de varredura. Os resultados mostraram que as energias absorvidas no ensaio de impacto pelos corpos-de-prova simulados cumprem com os requisitos exigidos pela norma API 5L para o metal base sem simulação e que as microestruturas observadas variam segundo o tipo de ciclo térmico aplicado a cada posição do tubo. / API 5L Grade X80 steel are high strength low alloy steels (HSLA) used in the manufacture of pipes for transporting oil and gas by pipelines. API 5L X80 pipes are characterized by having excellent mechanical properties such as tensile strength, toughness, ductility, corrosion resistance, and good weldability. These pipes bring many benefits, for example, the economic factor related to the good mechanical strength of these tubes which can be produced with smaller wall thicknesses. This reduction in thickness lowers costs for transportation, construction, welding and installation. In addition, these tubes can be fabricated with large diameters, allowing the transport of large amounts of fluids at high pressures and flow rates. The toughness gives, to this material, the characteristic of being resistant to brittle fracture, since these tubes mostly work in aggressive environmental conditions. The objective of this work is to physically simulate and study the mechanical properties of regions of the heat affected zone (HAZ) produced by different thermal cycles, which occur when the duct pipe is manufactured and assembled. The idea was to study the HAZ produced in the pipe manufactured by the UOE process (longitudinal weld) and the welding done in the field when the tube is mounted (HAZ beyond the intersection between the longitudinal and circumferential welding). Charpy V samples were machined in the L-T and T-L orientations and in the longitudinal weld in the center of the tube. These samples were subjected to single thermal cycles with maximum temperatures of 650, 800, 950 and 1300°C and multipass thermal cycling with maximum temperatures of 950-800 and 950-800-650°C. The samples were subjected to different tests and characterizations. Impact tests were made at 0°C, measured the lateral expansion produced and the surface fracture were examined under SEM. Vickers 300g microhardness was also measured in the simulated HAZ region. The microstructure of the HAZ was characterized by optical microscopy with conventional etching and Klemm colorful etching, and scanning electron microscopy. Quantitative metallography was used to obtain the amount of pearlite in the matrix of samples. The Charpy V fracture propagation path trajectory in the simulated microstructure was analyzed with optical microscopy and scanning electron microscopy. The results showed that the Charpy V absorbed energy by the simulated samples complies with the requirements of the API 5L standard for the base metal without simulation and the HAZ observed microstructures vary according to the thermal cycle type applied to each tube position.

L’étude se situe dans le cadre de la recherche de gains de performance de structures d’isolations passives pour l’offshore profond. Le travail proposé a pour support des analyses expérimentales et numériques de tubes revêtus par des matériaux isolants utilisés en eau profonde pour transporter du fluide chaud. Le raboutage des tubes en acier, préalablement revêtus en atelier, nécessite un dégagement du revêtement aux extrémités pour réaliser l'opération d'assemblage (généralement par soudure). La partie dégagée est ensuite recouverte par un nouveau matériau pouvant être appliqué sur site. Ainsi l’isolation de cette partie du tube (Field Joint), qui est soumise à des chargements thermomécaniques en service, doit être optimisée pour assurer une durée de vie compatible avec les contraintes de l’exploitation offshore en eau profonde. Le travail comporte principalement quatre parties : - la modélisation du comportement thermique pour analyser l’évolution en temps et en espace de la température du matériau au cours de la fabrication, de la pose et en service sachant que pour les matériaux d’isolation le comportement mécanique est fortement dépendant de la température,- une partie expérimentale pour l’analyse du comportement des matériaux isolants en fonction de la température et en fonction de la pression hydrostatique qui est le principal chargement mécanique de ces structures en service,- la modélisation du comportement mécanique des isolants,- et une partie modélisation et simulation du comportement en service d'assemblages multi-matériaux de type industriel, avec prise en compte du comportement non-linéaire des constituants. / Ultra deep offshore oil exploitation presents new challenges to offshore engineering and operating companies. Such applications require the use of pipelines with an efficient thermal protection. Passive insulation materials are commonly used to guarantee the thermal performance of the pipes, and syntactic foams are now the preferred material for this application. The mechanical behaviour of such insulation materials is quite complex, associating time-dependent behaviour of polymers with damage behaviour of glass microspheres. In order to allow an optimisation of such systems, while ensuring in-service durability, accurate numerical models of insulation materials are thus required. During the service life in deep water, hydrostatic pressure is the most important mechanical loading of the pipeline, so this study aims to describe the mechanical behaviour of the material under such loading. Using a hyperbaric chamber, the analysis of the evolution of the volumetric strain with time, with respect to the temperature, under different time-evolutions of the applied hydrostatic pressure is presented in this paper. Such experimental results associated with the mechanical response of the material under uniaxial tensile creep tests, allow the development of a thermo-mechanical model, so that representative loadings can be analysed.

Made available in DSpace on 2016-04-25T20:19:53Z (GMT). No. of bitstreams: 1 Paulo Baltazar.pdf: 12348587 bytes, checksum: 62c8227228c6a07eedab0e1866fa84fa (MD5) Previous issue date: 2010-05-31 / Fundação Ford / In the 1980s, several government-sponsored projects were directed at improving the relationship between the Terena people and the white population. The most recent of those projects the construction of a gas pipeline running from Bolivia to Brazil served as a test case in that relationship. The negotiations around the implementation of the project brought to the surface the contrast between the decision making process which is characteristic of the Terena people and that of the non-indigenous authorities and their organizations in question. Up until then, the Terena leadership had never been consulted or invited to participate in the planning stage of projects aimed at the indigenous population. As a consequence, most of those projects and public policies have failed, due to the fact that they had been decided in the offices of the bureaucrats without the input of the receptors. The highlight of the gas pipeline project negotiations happened during a meeting between the representatives of the national and international agencies involved in the project, on the one hand, and the Terena leadership, on the other, whose venue was in Campo Grande, the capital of the State. On that occasion, the Terena clashed with the white representatives who proposed using the geographical distance between the Terena settlements and the actual pipeline as the sole factor in the financial compensation for the impact which the project would have on the indigenous territory and population. The argument advanced by the Terena leadership, at the time, was that the criterion proposed was contrary to their traditional decision making process. The Terena make their group decisions on the basis of the interaction between the extended family groups as well as the reciprocity of interests within their communities. The present study describes and analyzes negotiation which took place around the gas pipeline project vis-à-vis the features of the decision-making process which is characteristic of the Terena people. The chronology of the negotiation process is given as well as the attending results which derived from the entire process itself / Na década de 1980 vários foram os projetos de políticas publicas destinados aos Terena no Distrito de Taunay, com objetivo de facilitar a relação dos povos indígenas com o mundo do branco. O projeto mais recente foi a construção do Gasoduto Bolivia-Brasil que passa nas proximidades das terras indígenas, servindo de marco revelador no processo de negociação e de decisão das lideranças Terena. Até então as lideranças Terena nunca foram convidadas e nem tão pouco consultadas para participar na elaboração dos projetos destinados as populações indígenas. Como conseqüência, a maioria dos projetos de políticas publica fracassaram em decorrência de serem construídos em gabinetes, sem a participação da parte interessada. O fator mais importante nesta construção do Gasoduto foi a reunião que aconteceu, em Campo Grande-MS, entre os representantes institucionais nacionais e internacionais envolvidos no projeto e as lideranças indígenas. As lideranças Terena reprovaram a metodologia apresentada na reunião que usava a distancia como critério empregado pela empresa responsável na construção do Gasbol. As lideranças Terena argumentaram que o critério de distancia não faz parte do processo decisório dos Terena, que se baseia na interação entre grupos familiares extensas, bem como a reciprocidade no interesse comum e que são povos unidos independente de distancia. Passados dez anos, a implantação do Gasoduto, os recursos aplicados nas aldeias em sua maior parte não trouxeram resultados desejados. A explicação de certos fracassos tem como matriz a desvalorização e desconhecimento do processo decisório do Terena

Made available in DSpace on 2016-04-26T14:52:33Z (GMT). No. of bitstreams: 1 Paulo Baltazar.pdf: 12348587 bytes, checksum: 62c8227228c6a07eedab0e1866fa84fa (MD5) Previous issue date: 2010-05-31 / Fundação Ford / In the 1980s, several government-sponsored projects were directed at improving the relationship between the Terena people and the white population. The most recent of those projects the construction of a gas pipeline running from Bolivia to Brazil served as a test case in that relationship. The negotiations around the implementation of the project brought to the surface the contrast between the decision making process which is characteristic of the Terena people and that of the non-indigenous authorities and their organizations in question. Up until then, the Terena leadership had never been consulted or invited to participate in the planning stage of projects aimed at the indigenous population. As a consequence, most of those projects and public policies have failed, due to the fact that they had been decided in the offices of the bureaucrats without the input of the receptors. The highlight of the gas pipeline project negotiations happened during a meeting between the representatives of the national and international agencies involved in the project, on the one hand, and the Terena leadership, on the other, whose venue was in Campo Grande, the capital of the State. On that occasion, the Terena clashed with the white representatives who proposed using the geographical distance between the Terena settlements and the actual pipeline as the sole factor in the financial compensation for the impact which the project would have on the indigenous territory and population. The argument advanced by the Terena leadership, at the time, was that the criterion proposed was contrary to their traditional decision making process. The Terena make their group decisions on the basis of the interaction between the extended family groups as well as the reciprocity of interests within their communities. The present study describes and analyzes negotiation which took place around the gas pipeline project vis-à-vis the features of the decision-making process which is characteristic of the Terena people. The chronology of the negotiation process is given as well as the attending results which derived from the entire process itself / Na década de 1980 vários foram os projetos de políticas publicas destinados aos Terena no Distrito de Taunay, com objetivo de facilitar a relação dos povos indígenas com o mundo do branco. O projeto mais recente foi a construção do Gasoduto Bolivia-Brasil que passa nas proximidades das terras indígenas, servindo de marco revelador no processo de negociação e de decisão das lideranças Terena. Até então as lideranças Terena nunca foram convidadas e nem tão pouco consultadas para participar na elaboração dos projetos destinados as populações indígenas. Como conseqüência, a maioria dos projetos de políticas publica fracassaram em decorrência de serem construídos em gabinetes, sem a participação da parte interessada. O fator mais importante nesta construção do Gasoduto foi a reunião que aconteceu, em Campo Grande-MS, entre os representantes institucionais nacionais e internacionais envolvidos no projeto e as lideranças indígenas. As lideranças Terena reprovaram a metodologia apresentada na reunião que usava a distancia como critério empregado pela empresa responsável na construção do Gasbol. As lideranças Terena argumentaram que o critério de distancia não faz parte do processo decisório dos Terena, que se baseia na interação entre grupos familiares extensas, bem como a reciprocidade no interesse comum e que são povos unidos independente de distancia. Passados dez anos, a implantação do Gasoduto, os recursos aplicados nas aldeias em sua maior parte não trouxeram resultados desejados. A explicação de certos fracassos tem como matriz a desvalorização e desconhecimento do processo decisório do Terena

Made available in DSpace on 2014-12-17T15:41:49Z (GMT). No. of bitstreams: 1 ErileideCR_DISSERT.pdf: 2520187 bytes, checksum: cbaac2eaf2812c34709374f87564cb10 (MD5) Previous issue date: 2010-07-12 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Corrosion is an important phenomenon that frequently occurs in the oil industry, causing surface ablation, such as it happens on the internal surfaces of oil pipes. This work aims to obtain new systems to reduce this specific problem. The surfactants SDS, CTAB, and UNITOL L90 (in micellar and microemulsionated systems) were used as corrosion inhibitors. The systems were obtained using a C/S ratio of 2, butanol as cosorfactant, kerosene as oil phase and, as water phase, NaCl solutions of 0.5M with pH = 2, 4, and 7. Microemulsion regions were found both for direct and inverse micelles. SDS had the higher microemulsion region and the area was not dependent of pH. The study of micellization of these surfactans in the liquid-gas interface was carried out via the determination of CMC from surface tension measurements. Regarding microemulsionated systems, in the case of CTAB, CMC increased when pH was increased, being constant for SDS and UNITOL L90. Concerning micellar systems, increase in pH caused decrease and increase in CMC for SDC and CTAB, respectively. In the case of UNITOL L90, CMC was practically constant, but increased for pH = 4. The microemulsionated systems presented higher CMC values, except for UNITOL L90 L90. The negative values of free energy of micellization indicated that the process of adsorption was spontaneous. The results also indicated that, comparing microemulsionated to systems, adsorption was less spontaneous in the case of SDS and CTAB, while it did not change for UNITOL L90. SAXS experiments indicated that micelle geometry was spherical, existing also as halter and flat micelles, resuting in a better inght on the adsorption at the liquid-solid interface. Efficiency of corrosion inhibition as determined by electrochemical measurements, from corrosion currents calculated from Tafel extrapolation indicuting heat showed surfactants to be efficient even at low concentrations. Equilibrium isotherm data were fitted to the Freundlich model, indicating that surfactant adsorption occurs in the form of multilayers / A corros?o ? um fen?meno presente em diversos seguimentos da ind?stria do petr?leo, causando desgastes em superf?cies de equipamentos met?licas, como exemplo a corros?o interna nos oleodutos. Este trabalho visa obter novos sistemas qu?micos para diminuir tal problema. Os tensoativos utilizados como inibidores de corros?o foram o SDS, CTAB e UNITOL L90 em sistemas micelares e microemulsionados. Para obten??o dos sistemas microemulsionados utilizou-se uma raz?o C/T=2, butanol como cotensoativo, querosene como fase ?leo e como fase aquosa utilizou-se solu??es de NaCl 0,5M nos pH s 2, 4 e 7. As regi?es de microemuls?o encontradas para os tr?s tensoativos s?o formadas por micelas diretas e inversas. A ?rea se mant?m constante com a varia??o do pH, o SDS tem maior regi?o de microemuls?o. O estudo da miceliza??o destes tensoativos na interface l?quido-g?s foi realizado a partir de medidas de tens?o superficial obtendo os valores de c.m.c, os quais foram particamente constantes para os sistemas microemulsionados com os tensoativos SDS e UNITOL L90 L90, e aumentaram para o CTAB quando elevou-se o pH. Os valores de c.m.c para os sistemas micelares com os tensoativos SDS e CTAB diminu?ram e aumentaram, respectivamente, quando aumentou-se o pH. J? o UNITOL L90 apresentou valores praticamente constantes, por?m foi maior em pH 4. Os sistemas microemulsionados apresentaram valores de c.m.c maiores, exceto para o tensoativo UNITOL L90. Os valores negativos de energia livre de miceliza??o indicaram que o porcesso de adsor??o ? espont?neo. Os resultados mostraram que os sistemas microemulsionados para os tensoativos SDS e CTAB foram menos espont?neos comparados ao sistema micelar, enquanto o UNITOL L90 apresentou valores praticamente constantes. Experimentos com SAXS mostraram que as geometrias das micelas foram esf?ricas, existindo ainda na forma de halteres ou de micelas achatadas, o que facilitou a compreens?o do estudo de adsor??o na interface l?quido-s?lido. As efici?ncias de inibi??o ? corros?o foram determinadas mediante medidas eletroqu?micas, a partir das correntes de corros?o encontradas atrav?s da extrapola??o de Tafel. Os tensoativos estudados se mostraram eficientes mesmo em baixas concentra??es. Os dados experimentais de ajustaram ao modelo da isoterma de Freundlich, indicando que a adsor??o dos tensoativos ocorre em multicamadas

The ability to backfill leadership positions has become a key focus of business leaders since 2005 when the baby boom workforce started to age. An aging workforce threatens the capability of business leaders to develop leadership pipelines to ensure business success. Grounded by the social exchange theory, the purpose of this qualitative single case study was to explore successful strategies that technology services managers used to align core business objectives to improve succession planning at a technology services organization located in Dallas, Texas. Data collection and triangulation included semi structured telephone interviews with 12 technology services managers, company documents, and archival information. Data analysis included the examination of rich text data, coding, and classification of themes using Yin's 5-step approach. Four themes emerged, revealing that these managers (a) created and sustained a leadership talent pipeline for high potential employees for future leadership roles; (b) sourced internal candidates with core leadership competencies; (c) remediated leadership skills gaps through developed relationships and documented processes; and (d) re-engineered the replacement planning process for the internal leadership talent pipeline. Implications for positive social change include the potential for technology services managers to implement effective succession planning strategies that could increase employee morale, enhance profitability and growth, and promote healthy community partnerships.

School-Wide Positive Behavioral Interventions and Supports (SWPBIS) is a school disciplinary framework seen as an effective tool to replace school disciplinary practices that contribute to the school to prison pipeline (STPP). While evidence suggests that SWPBIS can help improve school discipline and lower suspension/expulsion rates, it has not been shown to consistently decrease racial disciplinary disparities. This study thematically analyzed semi-structured interviews of educational staff at one high school at the outset of SWPBIS implementation to understand their perceptions of school discipline and the potential for SWPBIS to address root causes of racial disciplinary disproportionality. Using a critical race theory analytical lens to center issues of race and racism, the findings revealed a school that is deeply structured in Whiteness. Participants described the school as “two schools in one”—one that is largely White, affluent, and high-achieving and another that is predominantly Black, economically disadvantaged, and achieving at lower levels. Educators were open to key elements of SWPBIS, such as positive discipline and school-wide consistency in disciplinary practices. And while many participants identified systemic barriers to achieving equity, they simultaneously relied on discursive strategies that upheld Whiteness. These findings suggest that SWPBIS has the potential to be an alternative to punitive school discipline, but faces multiple barriers in addressing disciplinary disproportionality. The segregated and stratified school structure raises questions about whom SWPBIS is for and who will bear the burden of implementation.