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Desacoplamento de perturbações por realimentação dinâmica regular para sistemas não-lineares afins. / Distrubance decoupling by regular dynamic feedback for nonlinear affine systems.Paulo Sergio Pereira da Silva 28 April 1992 (has links)
Neste trabalho, consideramos o problema de desacoplamento de perturbações por realimentação dinâmica regular do estado para sistemas não lineares afins. Utilizando a abordagem geométrica-diferencial, estabelecemos condições necessárias e suficientes de solução de tal problema. Mostramos que tais condições são baseadas na geometria de um sistema estendido, obtido pela colocação de integradores em série com as entradas do sistema original. Quando tal problema e solúvel, mostramos também que o algoritmo de extensão dinâmica permite a construção do compensador solução. Como um subproduto de tais técnicas, obtemos uma forma geométrica de determinação da estrutura algébrica no infinito, através da geometria do sistema estendido. / In this work we consider the Problem of Disturbance Decoupling by Regular Dynamic Feedback for the class of affine nonlinear systems. We use the so-called Differential Geometric Approach to derive the necessary and sufficient conditions for this problem\'s solution. We show that the solvability of this problem is governed by the geometry of an Extended System obtained by putting integrators in series with the inputs of the original system. When the necessary conditions are satisfied, we show that the well known dynamic extension algorithm can be used to construct a solution. We also show that the algebraic structure at infinity can be computed by geometric methods with the aid of the Extended System.
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The organization of universities through the lens of Academic Workload Model : actors and higher education system / L'organisation de l'université au prisme du dispositif de l'Academic Workload Model : acteurs et système de l'enseignement supérieurAri Ragavan, Neethiahnanthan 13 December 2016 (has links)
Cette thèse engagée à partir des enjeux de la transformation du paysage international de l’éducation supérieure et ses implications au niveau local et national de l’organisation des universités. Basé dans une approche néo-rationaliste des interactions entre acteurs et les systèmes d’enseignement supérieure, le concept gigogne d’arènes académiques et les processus de couplage/découplage, l’analyse se focalise sur le cas d’étude du développement, implantation et ajustement d’un dispositif de calcul des services d’enseignant-chercheur. La méthodologie est basée sur une observation participante de longue durée, l’action-recherche et la méthode d’étude de cas. L’analyse quantitative relative à la transformation de la structure et de la performance des enseignants-chercheurs avec les accomplissements de l’université est combinée avec l’analyse qualitative de données collectées par des entretiens individuels et de groupes conduits avec des enseignants-chercheurs, des membres de la direction de l’université ainsi qu’avec des experts de l’enseignement supérieur malaisien et international. Les analyses conduites démontrent – au niveau de l’organisation universitaire – la capacité de négociation des académiques et du management par rapport à leurs rôles et conditions d’avancement de carrière est central dans l’instrumentation du dispositif de calcul des services. Au niveau national, les analyses soulignent la complémentarité entre institutions d’éducation supérieure privées et publiques. Au niveau international, les analyses soulignent la capacité d’ajustement du système universitaire et des politiques malaisiennes relatives à l’enseignement supérieur et à la recherche pour la régulation de leurs positions dans l’arène académique internationale. / This thesis is based on issues concerning the changing landscape of higher education globally and its implication at the local and national levels of the organization of universities. Drawn from the neo-rationalism perspective on the interactions between actors and higher education systems, the ‘gigogne’ concept of the academic arenas and coupling / decoupling processes, the analysis focuses on the case study of the development, implementation and adjustment of academic workload model. The methodology applied is based on long-term participant observation, action research and case study approaches. It is mixing quantitative analysis of the transformation of the academics’ performance and structure with the university’s achievement. On the other hand, this quantitative approach is complimented with the qualitative analysis of data gathered through formal interviews and focus groups, conducted with academics, senior management of the university and as well as experts of the higher education system in Malaysia and globally.Conclusions from the findings demonstrate – at the organizational level of the university - the capability of negotiation of the academics and senior management with regards to their roles and conditions of career advancement is central in the instrumentation of the academic workload system. At the national level, it highlights the complementary action between public and private higher education institutions. At the international level, it stresses on the capability of adjustment of the university organization system and the Malaysian higher education policy to redefine itself in regulating its position at the arenas of international bodies in higher education.
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Refining the chemical and kinetic decoupling description of thermally produced dark matterBinder, Tobias 13 March 2019 (has links)
No description available.
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Analyse et commande de systèmes multivariables. Application à un turbopropulseur. / Analysis and control of multivariable processes – Applied to a turboprop engineLe Brun, Christophe 26 June 2015 (has links)
Les travaux entrepris au cours de cette thèse ont permis de concevoir des stratégies de commande de systèmes multivariables (outils d’analyse et méthodes de synthèse) en vue de leur application au développement de lois de commande d’un turbopropulseur.D’un point de vue fonctionnel, un turbopropulseur est un système multivariable comprenant deux grandeurs de commande : le débit carburant à injecter dans la chambre de combustion et le pas de l’hélice, ainsi que deux grandeurs de sortie : la puissance délivrée par l’hélice et sa vitesse de rotation. Ces variables sont fortement couplées, ce qui signifie que des variations de l’une entraînent des écarts sur l’autre. L’objectif de ces travaux est de synthétiser des lois de commande facilement ajustables, permettant de respecter des spécifications classiques en Automatique (temps de réponse, dépassement, erreur statique) et de réduire les couplages entre les différentes grandeurs régulées. Dans ce contexte industriel, les approches décentralisées sans et avec découplage sont envisagées. La stratégie décentralisée pure met en œuvre un correcteur diagonal, ce qui revient à asservir un système par plusieurs boucles monovariables indépendantes. Bien que relativement facile à synthétiser et à implanter, la stratégie décentralisée ne permet pas d’atteindre les performances souhaitées en présence d’interactions importantes. Dans ce cas, il est possible de l’associer à des compensateurs permettant de diminuer les interactions.Une part importante de ces travaux de recherche concerne le développement méthodologique de ces stratégies. La définition d’une stratégie de commande est la première étape. Pour cela, la quantification du niveau d’interaction dans un système se révèle importante. Celle-ci peut être réalisée à l’aide de différentes méthodes et indicateurs qui s’appuient sur les réponses fréquentielles ou temporelles du système, ou encore sur les grammiens de commandabilité et d’observabilité. Une procédure systématique d’analyse des interactions a été proposée afin de déterminer la stratégie de commande la plus adaptée en fonction des interactions. Dans le cas où l’analyse des interactions conduit à adopter une stratégie décentralisée, les régulateurs peuvent être synthétisés à l’aide de méthodes monoboucles ou multiboucles. Les premières ne prennent pas en compte les interactions tandis que les secondes, plus élaborées mais également plus complexes à mettre en œuvre, permettent de les prendre spécifiquement en compte. A la suite de l’analyse de ces méthodes, une étude récapitulative présentant les méthodes préconisées en fonction du procédé et des objectifs, est finalement proposée. Dans le cas où l’analyse des interactions montre un niveau de couplage trop important, il est possible d’associer des compensateurs à la régulation décentralisée. Les compensateurs ont pour but de découpler les commandes vis-à-vis des sorties du procédé. Différentes méthodes et structures de découplage ont été étudiées et comparées. Une procédure de découplage, composée des méthodes considérées comme les plus efficaces a finalement été mise en place. / In this Ph.D. thesis, we explore the different steps of designing a decentralized control applied on a turboprop engine.From the control point of view, the turboprop engine is a TITO (Two-Input Two-Output) process. The fuel flow is used to control the shaft power while the blade pitch angle is used to control the propeller speed. The turboprop presents important couplings between manipulated variables and controlled variables. When the fuel flow changes, the propeller speed is impacted. Similarly, when controlling the blade pitch angle to change the propeller speed to another level, the shaft power is affected, particularly during the transient states. The main objective of this research thesis is to design control laws for the turboprop. Beside technical specifications like response time and overshoot, couplings between loops have to be reduced as much as possible and control laws have to be robust to model uncertainties. For this industrial environment a decentralized strategy (with or without compensators) has been chosen. The decentralized strategy consists in designing monoloop controllers in order to drive the multivariable system. The decentralized strategy presents important benefits, such as flexibility as well as design simplicity, but is not efficient in presence of heavy couplings. In that case, it is possible to use compensators that reduce existing process interactions before designing the monoloop controllers.An important part of this work focuses on the development of these different strategies.The first step is the choice of the control structure, which strongly depends on the level of interaction. Despite the availability of different metrics - based on frequential responses, temporal responses, or Gramian – it is not easy to know which one is the most appropriate. Based on the analysis of couplings with different metrics, a procedure is proposed in order to choose the structure and the controllers design method.If the coupling analysis leads to adopt a decentralized strategy, the controllers can be designed using monoloop or multiloop methods. The first ones are simple but do not take couplings into account, whereas multiloop methods take specifically couplings into account but are more complicated. These tuning methods have been studied and recommendations have finally been made to choose the most appropriated method depending on the process and the requirements.In cases where the couplings analysis reveals a high couplings level, compensators can be associated with the decentralized strategy. The objectives of the compensators are to reduce couplings in the system and to facilitate the design of monoloop controllers. Several decoupling structures have been studied and compared. A decoupling procedure has then been proposed.These methodological studies have been applied to the turboprop engine. Following the coupling analysis, a decentralized strategy with decoupling has been chosen. After following the decoupling procedure and trying different solutions, the inverted decoupler has been adopted. Considering the dynamics of the system and the total decoupling provided by the inverted decoupler, PI controllers have been used and a monoloop tuning method has been chosen. In order to guarantee the desired performances over the whole flight envelope, control laws have been interpolated, using a gain scheduling technique. The structured singular value approach has then been used to demonstrate the robustness of the control laws with model uncertainties. Control laws have finally been implemented in the control software and simulation results have illustrated their good performances.
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Decentralized state-space controller design of a large PHWRKhan, Nafisah 01 November 2009 (has links)
The behaviour of a large nuclear reactor can be described with sufficient accuracy using a
nodal model, like the spatial model of a 540 MWe large Pressurized Heavy Water
Reactor (PHWR). This model divides the reactor into divisions or nodes to create a
spatial model in order to control the xenon induced oscillations that occur in PHWRs.
However, being such a large scale system, a 72nd-order model, it makes controller design
challenging. Therefore, a reduced order model is much more manageable. A convenient
method of model reduction while maintaining the important dynamics characteristics of
the process can be done by decoupling. Also, due to the nature of the system,
decentralized controllers could serve as a better option because it allows each controller
to be localized. This way, any control input to a zone only affects the desired zone and
the zones most coupled with, thus not causing a respective change in neutron flux in the
other zones.
In this thesis, three decentralized controllers were designed using the spatial model of a
540 MWe large PHWR. A decoupling algorithm was designed to divide the system into
three partitions containing 20, 27, and 25 states each. Reduced order sub-systems were
thus created to produce optimal decentralized controllers. An optimal centralized
controller was created to compare both approaches. The decentralized versus centralized
controllers’ system responses were analyzed after a reactivity disturbance. A fail-safe
study was done to highlight one of the advantages of decentralized controllers. / UOIT
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Timing and Characterization of the Change in the Redox State of Uranium in Precambrian Surface Environments: A Proxy for the Oxidation State of the AtmospherePollack, Gerald D. 08 December 2008 (has links)
The redox-sensitive geochemical behavior of uranium permits the use of Th/U ratios as a geochemical proxy for the oxidation state of the atmosphere and oceans during sedimentary processes. Due to the effects of post-depositional uranium mobility on Th/U ratios during events involving oxygenated fluids, direct measurements of Th/U ratios are often misleading, but the whole rock Pb isotope composition may be used to determine a sample¡¦s apparent time-integrated Th/U ratio (ƒÛa) and the timing associated with the onset of the U-Th-Pb geochemistry. Rare earth element (REE) concentrations were determined by isotope dilution mass spectrometry to evaluate the influence of multiple provenance components and potential mobility of Th, U, and Pb during post-depositional processes on the Th/U ratio. The Pb isotope compositions and REE concentrations were determined for six Paleoproterozoic sedimentary sequences, which were the focus of previous studies involving the timing of the rise of atmospheric oxygen. The Mount McRae Shale, Huronian Supergroup, and Zaonezhskaya Formation have been interpreted as experiencing post-depositional alteration (perhaps associated with orogenic events) due to Pb-Pb ages that are younger than the likely depositional age and observed fractionation of REE in chondrite normalized REE patterns and interelement REE ratios (e.g. La/Nd, La/Yb, Eu/Eu*). Similar geochemical proxies have been interpreted as sedimentary geochemical features of the Timeball Hill Formation, Hotazel Formation, and Sengoma Argillite Formation. This study of Paleoproterozoic sedimentary units constrains the onset of U-Th decoupling, most likely due to the onset of oxidative weathering conditions, began by 2.32 Ga, the latest.
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Bankers etiska riktlinjer, frikopplade i praktiken? : En kvalitativ undersökning om de anställdas förhållningssätt till bankens etiska riktlinjer / Code of ethics in banks, decoupled in practice? : A qualitative survey of employees' approach to the Bank's ethical guidelinesJohnsson, Rebecca, Johnsson, Jacob January 2018 (has links)
Under de senaste åren har det gjorts flertalet ansatser till att skapa etiska koder som ska bidra till att öka det etiska handlandet i organisationer. Etik kan kommuniceras och tolkas på olika sätt, och forskningslitteraturen har beskrivit olika perspektiv och förklaringar till varför medarbetarnas förhållningssätt till ett företags etiska riktlinjer är som det är. Tidigare forskning inom frikopplingsteorin har i stor utsträckning åskådliggjort både orsaker och konsekvenser av frikoppling på organisationsnivå. Men det finns en brist på forskning som undersöker hur enskilda organisationsmedlemmars förhållningsätt påverkar frikopplingen. Det deskriptiva syftet är att undersöka skillnader mellan bankers etiska riktlinjer och medarbetarnas förhållningssätt. Det teoretiska syftet med uppsatsen är att identifiera möjliga förklaringar till varför förhållningssättet är som det är. Undersökningen har en kvalitativ kundskapsansats där insamlad data består av primär data ifrån intervjuer och sekundär data ifrån bankernas etiska riktlinjer. Empirin visar på att det finns skillnader i de anställdas förhållningssätt till de etiska riktlinjerna, och resultaten visar att det förekommer frikoppling i alla tre banker. De skillnader som studien påvisar är att medarbetarnas förhållningssätt till de etiska riktlinjerna skiljer sig beroende på de etiska riktlinjernas struktur. Olika perspektiv på strukturen ger olika faktorer som påverkar de anställdas förhållningssätt och ger en frikoppling mellan handling och de etiska riktlinjerna. Studien har begränsningar då resultatet inte kan generaliseras, detta på grund av att forskningsmetoden är en kvalitativ fallstudie samt att urvalet av respondenter är relativt lågt. Tidigare forskning inom frikopplingsteori har fokuserat på hur organisationen väljer att frikoppla struktur och handling, medan vår studie beskriver hur frikoppling uppstår på mikronivå, individnivå där de anställda frikopplar de etiska riktlinjerna olika beroende på riktlinjens struktur. Detta förklarar den variation som finns i frikopplingen och som ger olika orsaker till att frikoppling sker. Vi har i denna studie visat på att tidigare forskning med motstridiga studier har haft rätt i sina argument, men att detta beror på i vilken struktur av de etiska riktlinjer som studierna applicerats på. / In recent years, several efforts have been made to create ethical codes that will help to increase ethical behavior in organizations. Ethics can be communicated and interpreted differently and previously research literature has described different perspectives and explanations as to why employees' approach to corporate ethical guidelines is as it is. Previous research in decoupling theory has largely given significant light on both causes and results of decoupling at the organization level, but there is a lack of research that investigates individual organizational members and how their approaches affect the decoupling. The descriptive purpose is to study differences between banks' ethical guidelines and employee approaches. The theoretical purpose of the paper is to identify possible explanations as to why the attitude is as it is. The research method of the study has a qualitative approach where data consists of primary data from interviews and secondary data from the banks' ethical guidelines. The empirical data shows that there are differences in employee approach to the ethical guidelines, and the results show that there are decoupling in all three banks. The differences that the study shows is that employees' approach to the ethical guidelines differs depending on the structure of ethical guidelines. Different perspectives on the structure provide different factors that affect employee approaches and provide a decoupling between action and the ethical guidelines. The study has limitations as the result cannot be generalized, due to the fact that the research method is a qualitative case study and that the sample of respondents is relatively low. Previous research in decoupling theory has focused on how the organization chooses to decouple structure and action while our study describes how decoupling occurs at the micro level, individual level, where employees decouple the ethical guidelines depending on the structure of the guideline. This explains the variation in the decoupling and the causes for decoupling. We have shown in this study that previous research with contradictory studies is all right in their arguments but which of the study that can be applied depends on the structure of the ethical guidelines that the studies apply to.
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Evolução geoquímica do manto litosférico subcontinental do Vulcão Agua Poca, Província Basáltica Andino-Cuyana, Centro-Oeste da ArgentinaJalowitzki, Tiago Luis Reis January 2010 (has links)
O campo vulcânico Patagônico é composto pelo vulcanismo datado do Quaternário ao Cretáceo e está amplamente distribuído no ambiente geotectônico de extra back-arc continental. Onze vulcões associados à ocorrência de xenólitos mantélicos estão situados dos 36°13’S aos 44°52’S. Estes vulcões são dominantemente compostos por basanitos e a basaltos alcalinos, que são divididos em dois grupos com base em aspectos petrográficos, geoquímicos e isotópicos. (Grupos I e II). Estes Grupos estão relacionados a fontes mantélicas similares, mas foram submetidos a diferentes processos metassomáticos. Os Grupos I e I foram gerados a partir de baixas taxas de fusão a partir de uma fonte mantélica do tipo OIB na zona de estabilidade da granada, mas o Grupo II tem características de manto enriquecido (EMII) possivelmente herdadas de um agente metassomático relacionado à zona de subducção, enquanto que o Grupo I demonstra assinatura geoquímica de magmas tipo OIB relacionados a fontes mantélicas ricas em flogopita. Os basaltos alcalinos do vulcão Agua Poca (37º01’S - 68º07’W) pertencem ao Grupo II e são traquibasaltos. O vulcão Agua Poca é definido é piroclástico monogenético, é composto por intercalações de camadas de spatter e cinder, hospeda xenólitos mantélicos e está localizado a oeste da Província de La Pampa, no extremo norte da Argentina. As amostras de xenólitos mostram textura protogranular, protogranular a porfiroclástica, porfiroclástica e porfiroclástica a equigranular e são compostos por olivina (fosterita), ortopiroxênio (enstatita), clinopiroxênio (diopsídio) e espinélio (sp). Os xenólitos estudados são peridotitos da fácies espinélio e piroxenitos anidros em basaltos alcalinos do Pleistoceno com #Mg em rocha total de 89 a 91. As assinaturas geoquímicas desses xenólitos mostram correlação negativa entre os principais óxidos quando dispostos contra o #Mg e estão empobrecidos em elementos incompatíveis em relação ao manto primitivo (MP). Os xenólitos do vulcão Agua Poca são caracterizados pelo empobrecimento de ETRP e ETRM normalizados para o MP e pelo fracionamento de ETRL em relação aos ETRP (CeN/YbN = 0,15-0,5), com exceção da amostra HAP10 (1,46). Esse comportamento indica que os xenólitos do terreno Cuyania são o resultado de 1 a 10% de fusão do DMM (Manto Depletado) ou de 8 a 17% do MP (Manto Primitivo). Em geral, os peridotitos mostram anomalias positivas de Ba, U, Ta, Pb, Zr e Ti; e anomalias negativas de Rb, Th, Nb, La e Y, enquanto que os piroxenitos mostram anomalias positivas de Ba, U, Ta e Pb; e anomalias negativas de Th, Nb, La, Zr, Hf, Ti e Y. Curvas de mistura calculadas para o resíduo de fusão do MP/DMM com a composição de fluídos/sedimentos derivados de ambientes de subducção indicam interação do manto com até 3% de fluídos/sedimentos. As razões 87Sr/86Sr (0,702874 - 0,704999, com média de 0,704035) são muito similares àquelas definidas para peridotitos com fonte tipo OIB. Agua Poca tem razões 87Sr/86Sr, que estão abaixo daquelas definidas para peridotitos metassomatizados (usualmente >0,705). As razões de Nb/Ta sugerem a presença de um reservatório eclogítico refratário subductado fusão parcial gerando líquidos alcalinos com razões Nb/Ta supercondríticas. / The Patagonian Volcanic Field composed of late Cretaceous to Quaternary volcanism is widely distributed in a continental extra back-arc geotectonic environment. Eleven monogenetic volcanoes accompanied with ultramafic xenoliths are situated from 36°13′S to 44°52′S. These volcanoes are dominantly composed of basanite to alkaline basalt, which are divided into two groups, based on mineralogy, geochemical and isotope compositions (Groups I and II). These Groups are originated from the similar subcontinental mantle sources, but were undergone to different metasomatism processes. Groups I and II were generated from low melting degrees of an OIB-like garnet peridotite, but the Group II has enriched mantle (EMII) characteristics possibly inherited from on-going subduction related metasomatism, while Group I demonstrates the OIB-like signature, which might result from phlogopite-bearing in the subcontinental lithosphere. The alkaline basalts from Agua Poca volcano (37º01’S - 68º07’W) belong to the Group II and are trachybasalts. The Agua Poca volcano is a monogenetic pyroclastic volcano composed by intercalation of spatter and cinder layers, host ultramafic mantle xenoliths and is located in the West of the La Pampa Province, Northernmost of Argentine Patagonia. The xenoliths show protogranular, protogranular to porphyroclastic, porphyroclastic and porphyroclastic to equigranular textures, and are composed of olivine (fosterite), orthopyroxene (enstatite), clinopyroxene (diopside) and spinel (sp). The studied xenoliths are anhydrous spinel-bearing peridotite and pyroxenite xenoliths in Pleistocene alkali basalts with whole rock Mg# from 88 to 91. Geochemical signatures of the mantle xenoliths show negative correlation between main oxides against Mg# and depletion in incompatible elements compared to primitive mantle (PM). Agua Poca mantle xenoliths are characterized by flat Sun & McDonough (1989) primitive mantle (PM) normalized HREE and MREE patterns, and depletion of LREE compared to HREE (CeN/YbN = 0.15-0.5), with exception of the HAP10 (1.46) sample. These characteristics suggest that partial melting event is the main process responsible for the generation of these xenoliths. Model calculations suggest that the xenoliths are the result of 1 to 10% of DMM (Depleted Mantle MORB) or 8 to 17% of PM partial melting. Peridotite samples show positive anomalies of Ba, U, Ta, Pb, Zr and Ti; and negative anomalies of Rb, Th, Nb, La and Y, while the pyroxenite samples show positive anomalies of Ba, U, Ta and Pb; and negative anomalies of Th, Nb, La, Zr, Hf, Ti and Y. Mixing curves calculated to mixtures of melting residue of PM/DMM and fluid or sediment compositions related to subduction tectonic setting end members suggest up to 3% of interaction of the fluid sediment on the depleted mantle residue. 87Sr/86Sr ratios (0.702874 - 0.704999, with average of 0.704035) are similar to those defined to peridotites with OIB source (87Sr/86Sr = 0.70244 to 0.70502), being close to Depleted Mantle (DM; 87Sr/86Sr = 0.7023 to 0.7032) values. Nb/Ta ratios suggest that Agua Poca xenoliths were undergone to partial melting processes that generated alkaline magmas with superchondritic Nb/Ta ratios.
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Evolução geoquímica do manto litosférico subcontinental do Vulcão Agua Poca, Província Basáltica Andino-Cuyana, Centro-Oeste da ArgentinaJalowitzki, Tiago Luis Reis January 2010 (has links)
O campo vulcânico Patagônico é composto pelo vulcanismo datado do Quaternário ao Cretáceo e está amplamente distribuído no ambiente geotectônico de extra back-arc continental. Onze vulcões associados à ocorrência de xenólitos mantélicos estão situados dos 36°13’S aos 44°52’S. Estes vulcões são dominantemente compostos por basanitos e a basaltos alcalinos, que são divididos em dois grupos com base em aspectos petrográficos, geoquímicos e isotópicos. (Grupos I e II). Estes Grupos estão relacionados a fontes mantélicas similares, mas foram submetidos a diferentes processos metassomáticos. Os Grupos I e I foram gerados a partir de baixas taxas de fusão a partir de uma fonte mantélica do tipo OIB na zona de estabilidade da granada, mas o Grupo II tem características de manto enriquecido (EMII) possivelmente herdadas de um agente metassomático relacionado à zona de subducção, enquanto que o Grupo I demonstra assinatura geoquímica de magmas tipo OIB relacionados a fontes mantélicas ricas em flogopita. Os basaltos alcalinos do vulcão Agua Poca (37º01’S - 68º07’W) pertencem ao Grupo II e são traquibasaltos. O vulcão Agua Poca é definido é piroclástico monogenético, é composto por intercalações de camadas de spatter e cinder, hospeda xenólitos mantélicos e está localizado a oeste da Província de La Pampa, no extremo norte da Argentina. As amostras de xenólitos mostram textura protogranular, protogranular a porfiroclástica, porfiroclástica e porfiroclástica a equigranular e são compostos por olivina (fosterita), ortopiroxênio (enstatita), clinopiroxênio (diopsídio) e espinélio (sp). Os xenólitos estudados são peridotitos da fácies espinélio e piroxenitos anidros em basaltos alcalinos do Pleistoceno com #Mg em rocha total de 89 a 91. As assinaturas geoquímicas desses xenólitos mostram correlação negativa entre os principais óxidos quando dispostos contra o #Mg e estão empobrecidos em elementos incompatíveis em relação ao manto primitivo (MP). Os xenólitos do vulcão Agua Poca são caracterizados pelo empobrecimento de ETRP e ETRM normalizados para o MP e pelo fracionamento de ETRL em relação aos ETRP (CeN/YbN = 0,15-0,5), com exceção da amostra HAP10 (1,46). Esse comportamento indica que os xenólitos do terreno Cuyania são o resultado de 1 a 10% de fusão do DMM (Manto Depletado) ou de 8 a 17% do MP (Manto Primitivo). Em geral, os peridotitos mostram anomalias positivas de Ba, U, Ta, Pb, Zr e Ti; e anomalias negativas de Rb, Th, Nb, La e Y, enquanto que os piroxenitos mostram anomalias positivas de Ba, U, Ta e Pb; e anomalias negativas de Th, Nb, La, Zr, Hf, Ti e Y. Curvas de mistura calculadas para o resíduo de fusão do MP/DMM com a composição de fluídos/sedimentos derivados de ambientes de subducção indicam interação do manto com até 3% de fluídos/sedimentos. As razões 87Sr/86Sr (0,702874 - 0,704999, com média de 0,704035) são muito similares àquelas definidas para peridotitos com fonte tipo OIB. Agua Poca tem razões 87Sr/86Sr, que estão abaixo daquelas definidas para peridotitos metassomatizados (usualmente >0,705). As razões de Nb/Ta sugerem a presença de um reservatório eclogítico refratário subductado fusão parcial gerando líquidos alcalinos com razões Nb/Ta supercondríticas. / The Patagonian Volcanic Field composed of late Cretaceous to Quaternary volcanism is widely distributed in a continental extra back-arc geotectonic environment. Eleven monogenetic volcanoes accompanied with ultramafic xenoliths are situated from 36°13′S to 44°52′S. These volcanoes are dominantly composed of basanite to alkaline basalt, which are divided into two groups, based on mineralogy, geochemical and isotope compositions (Groups I and II). These Groups are originated from the similar subcontinental mantle sources, but were undergone to different metasomatism processes. Groups I and II were generated from low melting degrees of an OIB-like garnet peridotite, but the Group II has enriched mantle (EMII) characteristics possibly inherited from on-going subduction related metasomatism, while Group I demonstrates the OIB-like signature, which might result from phlogopite-bearing in the subcontinental lithosphere. The alkaline basalts from Agua Poca volcano (37º01’S - 68º07’W) belong to the Group II and are trachybasalts. The Agua Poca volcano is a monogenetic pyroclastic volcano composed by intercalation of spatter and cinder layers, host ultramafic mantle xenoliths and is located in the West of the La Pampa Province, Northernmost of Argentine Patagonia. The xenoliths show protogranular, protogranular to porphyroclastic, porphyroclastic and porphyroclastic to equigranular textures, and are composed of olivine (fosterite), orthopyroxene (enstatite), clinopyroxene (diopside) and spinel (sp). The studied xenoliths are anhydrous spinel-bearing peridotite and pyroxenite xenoliths in Pleistocene alkali basalts with whole rock Mg# from 88 to 91. Geochemical signatures of the mantle xenoliths show negative correlation between main oxides against Mg# and depletion in incompatible elements compared to primitive mantle (PM). Agua Poca mantle xenoliths are characterized by flat Sun & McDonough (1989) primitive mantle (PM) normalized HREE and MREE patterns, and depletion of LREE compared to HREE (CeN/YbN = 0.15-0.5), with exception of the HAP10 (1.46) sample. These characteristics suggest that partial melting event is the main process responsible for the generation of these xenoliths. Model calculations suggest that the xenoliths are the result of 1 to 10% of DMM (Depleted Mantle MORB) or 8 to 17% of PM partial melting. Peridotite samples show positive anomalies of Ba, U, Ta, Pb, Zr and Ti; and negative anomalies of Rb, Th, Nb, La and Y, while the pyroxenite samples show positive anomalies of Ba, U, Ta and Pb; and negative anomalies of Th, Nb, La, Zr, Hf, Ti and Y. Mixing curves calculated to mixtures of melting residue of PM/DMM and fluid or sediment compositions related to subduction tectonic setting end members suggest up to 3% of interaction of the fluid sediment on the depleted mantle residue. 87Sr/86Sr ratios (0.702874 - 0.704999, with average of 0.704035) are similar to those defined to peridotites with OIB source (87Sr/86Sr = 0.70244 to 0.70502), being close to Depleted Mantle (DM; 87Sr/86Sr = 0.7023 to 0.7032) values. Nb/Ta ratios suggest that Agua Poca xenoliths were undergone to partial melting processes that generated alkaline magmas with superchondritic Nb/Ta ratios.
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Framing Sustainability : A Qualitative Study of the Translation of the 2030 AgendaWallén, Camilla, Kardell, Kristina January 2018 (has links)
Following the increase of transnational organisations, global governance today is mainly relying on voluntary standards. One standard is the UN’s 2030 Agenda for Sustainable Development. This motivates a need to understand how such an idea unfolds within organisations and what impact global CSR standards have, leading to the research question: How are CSR standards deriving from global ideas translated into organisations and influencing sustainability activities? Based on a literature review of Scandinavian institutionalism, soft rules and standards, CSR, traveling of ideas, translation, identity and image, decoupling and aspirational talk, five assumptions were formulated as to what implications the standard might have. These are examined qualitatively through multiple case studies in the Swedish food industry using semi-structured interviews and examining CSR reports. The analysis find partial support for all assumptions. Main findings include the use of the 2030 Agenda mainly as a communication tool, constituting a common sustainability language and a platform for collaborations. The standard is thus interpreted as being symbolically translated. This open up possibilities for future research regarding the translation of standards and the implications of an facilitated way of framing sustainability work, adding the concept of symbolic translation to translation theory.
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