Nos sistemas de distribuição de alta e média tensão tem-se aumentado a utilização de linhas de distribuição de energia subterrâneas ou cabos subterrâneos. A ocorrência de faltas nas linhas afeta negativamente a qualidade da energia e o correto funcionamento da rede. O processo que leva a uma falta nos cabos é gradual e está caracterizado por uma série de subciclos de faltas incipientes associadas a uma tensão de arco. Estas, muitas vezes, passam despercebidas e, eventualmente, resultam em uma falta permanente. Os métodos clássicos de localização de faltas como as metodologias baseadas no cálculo da impedância aparente, as baseadas na inteligência artificial e as baseadas nas ondas viajantes são, habitualmente, aplicadas ao sistema depois de uma falta permanente acontecer e precisam de um ou mais ciclos do sinal para entregar uma resposta razoável. No entanto, as faltas nos cabos são um processo gradual, de curta duração (entre ¼ e ½ ciclo do sinal) e seria desejável localizar a falta incipiente antes de tornar-se permanente. Nesse contexto, esta pesquisa aborda o problema de localização de faltas incipientes. Assim, nesta tese propõe-se uma nova técnica de localização de faltas incipientes usando medições em um terminal, no domínio do tempo e que utiliza componentes de fase. Desta forma, são desenvolvidas duas novas formulações do modelo elétrico do sistema de distribuição com cabos subterrâneos durante uma falta incipiente. A abordagem proposta considera simultaneamente na sua formulação características da falta incipiente e dos sistemas de distribuição de energia, como a tensão de arco, o modelo Π nominal de parâmetros concentrados do cabo subterrâneo, o desequilíbrio do sistema e a condição da carga. A estimativa da distância da falta, junto com os parâmetros da falta incipiente, é obtida a partir da solução de um sistema sobredeterminado de equações lineares pela aplicação do método de mínimos quadrados ponderados não negativos. As formulações propostas permitem estimar a distância da falta em termos da reatância da linha até a falta. Além disso, é proposto um processo de compensação de corrente para estimar a corrente de falta; é aplicado um pré-processamento dos dados de entrada para suavizar o efeito do ruído que pode conter o sinal e, é aplicado um pós-processamento dos resultados para refinar e entregar a melhor estimativa obtida durante o processo de localização da falta. O desempenho da técnica proposta é avaliado mediante estudos de casos simulados em um circuito real de distribuição no Alternative Transients Program (ATP/EMTP) considerando análises de sensibilidade e comparativa. Também, o modelo da falta incipiente foi programado utilizando a ferramenta de MODELS do ATP/EMTP. Os resultados obtidos, considerando faltas incipientes simuladas que avaliam a influência da variação da magnitude de tensão de arco, do ruído aleatório inserido na tensão de arco, da distância da falta, da taxa de amostragem, do carregamento do sistema, do modelo de tensão de arco e de incertezas nas medições, indicam claramente que a abordagem proposta possui validade como técnica de localização de faltas incipientes, apresentando erros médios globais de 1,60% e 0,93%, respectivamente para cada formulação proposta. / The use of underground power distribution lines or underground cables in the high and medium voltage distribution systems has increased dramatically in recent years. The fault occurrence in the distribution lines negatively affects the power quality and the correct network operation. The process which leads to a fault in underground cables is gradual and is characterized by a series of sub-cycles of incipient faults associated with an arc voltage. These often are unnoticed and, eventually, results in a permanent fault. Classical fault localization methods such as the based-impedance, the based on artificial intelligent and the based on traveling waves are, usually, applied to the system after a permanent fault occurrence and need one or more signal cycles for providing a reasonable response. However, the faults in cables are a gradual process, with short duration (between ¼ to ½ of signal cycle) and would be desirable to locate the fault before this becomes a permanent fault. In this context, this research approaches the incipient faults location problem. Thus, in this thesis is proposed a new incipient fault location technique using single-end terminal measurement, in time-domain and employing phase components. In this way, two new formulations of the electrical model of the distribution system with underground cables during an incipient fault are developed. The proposed approach considers simultaneously in its formulation, incipient fault type and power distribution systems characteristics as arc voltage, unbalanced operation, load conditions and complete line model. The fault distance estimation, together with the incipient fault parameters, it is obtained from the solution of an overdetermined linear system of equations by the application of the non-negative weighted least squares estimator method. The proposed formulations allow estimating the fault distance in terms of the line reactance up to the fault. In addition, a load current compensation strategy is proposed to reduce its effect in the fault current estimation; an input data pre-processing is applied to smooth out the noise effect and a post-processing of the results is performed for estimation refinement and to provide the best estimate obtained during the fault location process. The proposed technique performance is evaluated through simulated cases studies in a real-life distribution network with underground cable data in the Alternative Transients Program (ATP/EMTP) considering sensitivity and comparative analyzes. Also, the fault model was programmed using the MODELS tool of ATP/EMTP. The obtained results, considering simulated incipient faults, which evaluate the influence of variations in the arc voltage magnitude, random noise percentage inserted in the arc voltage, fault distance, sampling rate, load dynamics, the arc voltage model and uncertainties in measurements, indicate clearly that the proposed approach is valid as incipient faults location technique, showing overall average errors of 1,60% and 0,93%, respectively for each proposed formulation.

Orientador: Edevar Luvizotto Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-05T20:04:30Z (GMT). No. of bitstreams: 1 Palhares_JulianaBarbosa_M.pdf: 1136611 bytes, checksum: 85a62466425d6655acb5af5bcc414c66 (MD5) Previous issue date: 2005 / Resumo: Nos sistemas de transporte de fluido líquido, têm-se a preocupação em combater às fugas ou vazamentos. Dessa fonna, este trabalho tem como objetivo aperfeiçoar o método de detecção de fugas em tubulações pelo método de resposta nos domínios fteqüência e tempo, utilizando como ferramentas matemáticas o Método da Matriz Transferência / Resposta em Freqüência e o Método das Características / Transfonnada Rápida de Fourier, sendo demonstradas as vantagens e desvantagens de cada método. E, como contribuição original, propõe um método de detecção de fugas através da análise de pulso de Alta Freqüência, localizando as fugas através da detenninação do tempo que um pulso emitido pela válvula leva para percorrer toda a tubulação e retomar à esta, denominado como Pulso Refletido / Abstract: In liquid fluid transport systems, there is a concem about avoiding leaks. Thus, this work has as objective to improve the leak detection method in pipes by úequency and time domains response method, being used as mathematical tools the method ofTransfer-Matrix / by úequency response and the Method of Characteristics / the Fast Fourier Transform, being demonstrated the advantages and disadvantages of each method. And, as new contribution, propose a leak detection method through the analysis of high frequency pulse, detecting the leaks through determination of time that a pulse produced by the valve takes to go through all pipe and come back, is denominated as a reflected pulse / Mestrado / Recursos Hidricos / Mestre em Engenharia Civil

Made available in DSpace on 2016-08-17T14:52:58Z (GMT). No. of bitstreams: 1 Jose Henrique Alves da Silva Filho.pdf: 1319180 bytes, checksum: 239eab8502370b1d91b48872e6bdc009 (MD5) Previous issue date: 2005-03-18 / This work proposes ONTOCADE (Ontology-based Environment for Computer- Aided Domain Engineering), an ontology-based CASE environment for analysis and design in Multi-Agent Domain Engineering. Success in Multi-Agent Domain Engineering, the process of creating reusable software abstractions for the development of a set of multi-agent software applications in a domain or problem-solving area, depends on the availability of appropriate methodologies and tools providing adequate support for ontologies, communications, mobility, and autonomy, among others central topics of agent-based systems. ONTOCADE supports the application of the phases of MADEM, a methodology for Multi-Agent Domain Engineering. According to the rules of integration for composing an environment, its tools use a shared data model and incorporate the knowledge of methods for coordinating and guiding the execution of the phases of the software development lifecycle. For that, ONTOCADE is based on ontologies, structures particularly appropriate for representing knowledge and high-level software abstractions, because they present clear and unambiguous terminology. ONTOCADE uses a generic ontology, ONTOMADEM, for guiding the user in modeling tasks. To define ONTOMADEM, it was used the MADEM knowledge to generate a semantic network with the representation of the concepts of the methodology. For its design, the ONTOMADEM was generated by mapping the semantic network to an ontology represented by a hierarchy of classes. To function as a runtime environment, it was chosen Protégé, an extensible platform for creating knowledge-based applications. ONTOMADEM is an extension of the meta-ontology of Protégé. In this way, ONTOCADE executes as a plugin, that is, an aggregated component, which takes advantages of all the functionalities provided by Protégé and offers specifics functions, such as domain and architectural modeling. / Este trabalho propõe ONTOCADE (Ontology-based Environment for Computer- Aided Domain Engineering), um ambiente CASE baseado em ontologias para análise e projeto na Engenharia de Domínio Multiagente (EDMA). O sucesso da Engenharia de Domínio Multiagente, processo para criação de abstrações de software reutilizáveis para a construção de sistemas multiagentes em um domínio ou área de solução de problemas, depende da disponibilidade de metodologias e ferramentas que ofereçam adequadamente suporte para ontologias, comunicações, mobilidade, autonomia e outros tópicos centrais relacionados aos sistemas baseados em agentes. ONTOCADE fornece suporte à aplicação das fases da MADEM, uma metodologia para EDMA. De acordo com as regras de integração para a constituição de um ambiente, as ferramentas que o compõem utilizam um modelo de dados compartilhado e incorporam o conhecimento de métodos para coordenar e guiar a execução das fases do ciclo de desenvolvimento de software. Por esta razão, o ambiente ONTOCADE é baseado em ontologias, estruturas particularmente apropriadas para representar conhecimento e abstrações de software de alto nível, pois apresentam terminologia clara e não ambígua. ONTOCADE utiliza uma ontologia genérica, a ONTOMADEM, para guiar o usuário na realização da modelagem. Na definição da ONTOMADEM é utilizado o conhecimento da MADEM para gerar uma rede semântica com a representação dos conceitos da metodologia. No projeto, a ONTOMADEM é construída mapeando a rede semântica a uma ontologia representada por uma hierarquia de classes. Como ambiente de execução do ONTOCADE, foi escolhido o Protégé, uma plataforma extensível para a criação de aplicações baseadas em conhecimento. A ONTOMADEM é uma extensão à meta-ontologia do Protégé. Desta forma, o ONTOCADE executa como um plugin, ou seja, um componente agregado ao Protégé, que se serve de todas as funcionalidades providas pela plataforma e oferece suas funções específicas, tais como modelagem de domínio e modelagem arquitetural.

The finite element method (FEM) is a widely-used numerical tool in the fields of structural dynamics, acoustics and electromagnetics. In this work, our goal is to develop robust FEM strategies for solving problems in the areas of acoustics, structures and electromagnetics, and then extend these strategies to solve multi-physics problems such as magnetohydrodynamics and structural acoustics. We now briefly describe the finite element strategies developed in each of the above domains. In the structural domain, we show that the trapezoidal rule, which is a special case of the Newmark family of algorithms, conserves linear and angular momenta and energy in the case of undamped linear elastodynamics problems, and an ‘energy-like measure’ in the case of undamped acoustic problems. These conservation properties, thus, provide a rational basis for using this algorithm. In linear elastodynamics variants of the trapezoidal rule that incorporate ‘high-frequency’ dissipation are often used, since the higher frequencies, which are not approximated properly by the standard displacement-based approach, often result in unphysical behavior. Instead of modifying the trapezoidal algorithm, we propose using a hybrid FEM framework for constructing the stiffness matrix. Hybrid finite elements, which are based on a two-field variational formulation involving displacement and stresses, are known to approximate the eigenvalues much more accurately than the standard displacement-based approach, thereby either bypassing or reducing the need for high-frequency dissipation. We show this by means of several examples, where we compare the numerical solutions obtained using the displacementbased and hybrid approaches against analytical solutions. We also present a monolithic formulation for the solution of structural acoustic problems based on the hybrid finite element approach. In the area of electromagnetics, since our goal is to ultimately couple the electromagnetic analysis with structural or fluid variables in a ‘monolithic’ framework, we focus on developing nodal finite elements rather than using ‘edge elements’. It is well-known that conventional nodal finite elements can give rise to spurious solutions, and that they cannot capture singularities when the domains are nonconvex and have sharp corners. The commonly used remedies of either adding a penalty term or using a potential formulation are unable to address these problems satisfactorily. In order to overcome this problem, we first develop several mixed finite elements in two and three dimensions which predict the eigenfrequencies (including their multiplicities) accurately, even for non-convex domains. In this proposed formulation, no ad-hoc terms are added as in the penalty formulation, and the improvement is achieved purely by an appropriate choice of the finite element spaces for the different variables. For inhomogeneous domains, ‘double noding’ is used to enforce the appropriate continuity conditions at an interface. Although the developed mixed FEM works very accurately for all 2D geometries and regular Cartesian 3D geometries, it has so far not yielded success for curved 3D geometries. Therefore, for 3D harmonic and transient analysis problems, we propose and use a modified form of the potential formulation that overcomes the disadvantages of the standard potential method, especially on non-convex domains. Electromagnetic radiation and scattering in an exterior domain traditionally involved imposing a suitable absorbing boundary condition (ABC) on the truncation boundary of the numerical domain to inhibit reflection from it. In this work, based on the Wilcox asymptotic expansion of the electric far-field, we propose an amplitude formulation within the framework of the nodal FEM, whereby the highly oscillatory radial part of the field is separated out a-priori so that the standard Lagrange interpolation functions have to capture a relatively gently varying function. Since these elements can be used in the immediate vicinity of the radiator or scatterer (with few exceptions which we enumerate), it is more effective compared to methods of imposing ABCs, especially for high-frequency problems. We show the effectiveness of the proposed formulation on a wide variety of radiation and scattering problems involving both conducting and dielectric bodies, and involving both convex and non-convex domains with sharp corners. The Time Domain Finite Element Method (TDFEM) has been used extensively to solve transient electromagnetic radiation and scattering problems. Although conservation of energy in electromagnetics is well-known, we show in this work that there are additional quantities that are also conserved in the absence of loading. We then show that the developed time-stepping strategy (which is closely related to the trapezoidal rule) mimics these continuum conservation properties either exactly or to a very good approximation. Thus, the developed numerical strategy can be said to be ‘unconditionally stable’ (from an energy perspective) allowing the use of arbitrarily large time-steps. We demonstrate the high accuracy and robustness of the developed method for solving both interior and exterior domain radiation problems, and for finding the scattered field from conducting and dielectric bodies. In the field of magneto-hydrodynamics, we develop a monolithic strategy based on a continuous velocity-pressure formulation that is known to satisfy the Babuska-Brezzi (BB) conditions. The magnetic field is interpolated in the same way as the velocity field, and the entire formulation is within a nodal finite element framework. Both transient and steady-state formulations are developed for two- and three-dimensional geometries. An exact linearization of the monolithic strategy ensures that rapid (quadratic) convergence is achieved within each time (or load) step, while the stable nature of the interpolations used ensure that no instabilities arise in the solution. Good agreement with analytical solutions, even with the use of very coarse meshes, shows the efficacy of the developed formulation.

L’énergie solaire photovoltaïque concentré (CPV) est une solution de remplacement prometteuse aux structures solaires conventionnelles. Ce type de structure modulable doit être optimisé afin d’être compétitif par rapport aux autres types de production d’énergie. Les forces de vent demeurent la première préoccupation dans la conception de la structure porteuse en acier d’un tel système. L’objectif principal de cette recherche est d’assembler des outils numériques et analytiques afin de prédire les caractéristiques de sa réponse dynamique sous charges de vent turbulent. La maîtrise de cette étape est essentielle afin d’étudier d’une façon plus générique des solutions d’optimisation de la structure support par rapport à sa réponse dynamique sous charges de vent. Pour ce faire, la méthodologie principale de cette étude est composée en trois parties : (i) étude expérimentale à grandeur nature de la réponse globale sous les conditions réelles du vent ; (ii) développement des modèles d’analyse numérique dans lesquels les caractéristiques de structures réelles et des modèles de forces aérodynamiques adéquates sont prises en compte ; (iii) application des outils développés dans une étude paramétrique pour évaluer plusieurs solutions à partir de cas d’étude dans le contexte d’une conception préliminaire. Cette thèse est présentée sous forme de deux articles qui ont été soumis dans des revues évaluées par des comités de lecture ainsi que d’un article soumis et présenté dans un congrès international qui démontrent les contributions de cette recherche pour améliorer les pratiques de calcul des charges de vent sur des structures de concentration solaire non conventionnelles. Ces articles sont présentés comme suit (a) Étude expérimentale à échelle réelle de la réponse d’un prototype de concentrateur solaire sous charges de vent. Ce premier article a permis la validation de calcul des coefficients de forces aérodynamiques statiques et la révision des hypothèses de l’application du code ASCE 7-10 pour prédire les forces maximales agissant sur la structure dans la direction du vent ; (b) l’analyse temporelle de la réponse dynamique d’une structure de concentrateur solaire sous charges de vent. Cette étude a montré que le modèle et la méthode d’analyse développés selon des hypothèses simplifiées permettaient de prédire correctement les caractéristiques statistiques de la réponse dynamique mesurée en cohérence avec la méthode spectrale stochastique ; (c) Étude des effets des configurations structurales et des paramètres de vent sur l’optimisation de structure solaires sous charges de vent. Cette étude paramétrique a mis en évidence l’importance de l’effet des paramètres structuraux et ceux définissant le vent sur l’optimisation de la conception structural pour ce type de structure. Des recommandations pour optimiser l’action dynamique dans une phase de conception préliminaire ont été proposées. Ce projet de recherche a démontré finalement l’importance d’étudier d’une façon juste et pratique la réponse dynamique sous charges de vent qui mène à résoudre des préoccupations d’optimisation liées à différents types de structures d’énergie solaire en adoptant des hypothèses pratiques pour les ingénieurs. / Abstract : Concentrated Solar Photovoltaic (CPV) is a promising alternative to conventional solar structures. These solar traking structures need to be optimized to be competitive against other types of energy production. Wind action is the main concern in the design of the steel support structure of such movable system. The main purpose of this research is to assemble advanced numerical and analytical tools that allows realistic dynamic study of structures under wind loading. This help to study accurately optimized alternative in term of selecting structural and wind site conditions parameters. The methodology of the present study involves three main steps : (i) experimental full-scale study of the global response under real life wind conditions ; (ii) numerical modeling that captures the characteristics of the real structures and include the aerodynamic force models to conduct time-domain dynamic analyses ; (iii) preliminary design application that include the study of the effect of stuctural and wind parameters in optimizing the dynamic wind action and consequently the steel support structure. The thesis is presented as an ensemble of three articles written for refereed journals and a conference that showcase the contributions of the present study to thoroughly understand the wind load effect on these nonconventionnel structures. The articles presented are as follow (a) full-scale measurement of the response of a CPV tracker structure prototype under wind load. The results presented in this first article help design engineers to evaluate the use of the aerodynamic force coefficients for calculating wind load on similar structures and to apply properly the ASCE7-10 in evaluating the maximum design wind force using the equivalent static approach ; (b) time-domain analysis of solar concentrator structure under gust wind. This study showed that the developed time-domain model using simplified hypothesis could successfully predict the statistical parameters of the measured dynamic response in coherence with the stochastic spectral approach ; (c) effect of structure configurations and wind characteristics on the design of solar concentrator support structure under dynamic wind action. This parametric study highlighted the importance of selecting structural and wind parameters in order to minimize the dynamic action and the steel support structure. Recommendations for optimizing dynamic wind action in a preliminary design phase were proposed. The present research project has shown the need to study accurately wind response to solve optimization concerns related to different type of solar system structures. In addition, this study proposes simplified methods that are useful for practical engineers when there is the need to solve similar problems.

The finite strip method (FSM) is a very efficient numerical method employed for performing the structural analysis of slender structures, such as cable-stayed bridges; the strip discretization of the model allows for the usage of a lower number of degrees of freedom, in comparison with the finite element method (FEM), while, as it will be discussed in the current research, the results obtained from both methods are in relatively good agreement. Moreover, to address the latest developments in the area of smart construction materials used for long-span bridges, the fiber reinforced polymer (FRP) composites were implemented for the bridge deck modeling, as part of a hybrid composite FRP cable-stayed bridge, and an extend laminate integrated finite strip method (LFSM) was applied for estimating the static structural performance of the hybrid composite FRP long-span cable-stayed bridge under several concentrated and uniformly distributed loadings. The free vibrations analysis was conducted for the Kap Shui Mun Cable-stayed Bridge model, and the natural frequencies were compared with the ones obtained from an FE model of the same bridge. One of the advantages of using the integrated finite strip method is that number of vibration modes, which can be included in the dynamic analysis when the effect of a sweeping sinus and a seismic loading are investigated when a conventional FE analysis would fail to converge. The outcomes of this research will set the stage for the hybrid long-span cable-stayed bridges modeling by the laminate integrated finite strip method (LFSM) which is more efficient and straightforward than the finite element analysis, for performing the static, free vibration, time domain, and frequency domain analyses.

Tato práce se zabývá analýzou power-bus struktur využitím metody založené na formulaci problému 2D hraniční integrální rovnicí ve frekvenční oblasti. Uvedená metoda byla implementována v Matlabu. Program umožňuje analyzovat obecné polygonální power-bus struktury s možností nastavení parametrů substrátu a libovolného počtu a umístění budících portů. Výstupem programu je frekvenční závislost rozložení elektrického pole mezi deskami struktury, vztahy mezi porty struktury vyjádřené např. impedanční maticí a vyzařovací diagram. Dále byla implementována možnost převodu výsledné impedanční matice do tzv. Touchstone formátu, pomocí něhož je možné modelovat analyzované struktury jako obecné N-porty (např. v ANSOFT Designeru), což umožňuje analýzu power-bus struktur s dalšími obvodovými prvky. Výsledky byly ověřeny pomocí existujících analytických vztahů pro jednoduché obdélníkové struktury, využitím komerčního simulačního programu a praktickým experimentem.

This thesis aims to examine how the domain Assyriology can be analyzed with bibliometrics. It uses the domain analytic perspective by Birger Hjørland and Hanne Albrechtsen. The metadata was collected through the Web of Science and the dataset covers the years 2016-2020 from the journals Akkadica, Journal of Near Eastern Studies, Ancient Near Eastern studies, Journal of Ancient Near Eastern Religions and Zeitschrift für Assyriologie und Vorderasiatische Archäologie. The domain was studied by analyzing citations, the documents, languages, place of publication, the age of references and the authors by visualizing patterns in figures and tables. Co-authorship analysis was used to display collaboration between countries. The content was analyzed with co-citation analysis of references and co-word analysis of title words to visualize the knowledge structures within the domain. The study found that Co-word analysis did give a general idea of different knowledge patterns but there were few clear structures. The co-citation analysis was found to reveal more clear structures though the references had a low citation rate and so might not be representative of the whole domain. It was found to be effective to use tables and figures to visualize certain aspects and patterns within the domain. In conclusion, bibliometrics was found to be effective to gain knowledge about the domain Assyriology. This is a two years master's thesis in Library and Information Science. / Den här uppsatsen ämnar att analysera hur domänen assyriologi kan analyseras med hjälp av bibliometri. Uppsatsen använder ett domänanalytiskt perspektiv av Birger Hjørland and Hanne Albrechtsen. Metadatan har samlats in från Web of Science och datasetet består material från tidsperioden 2016-2020 från tidskrifterna AkkAncient Near Eastern studies, adica, Journal of Near Eastern Studies, Journal of Ancient Near Eastern Religions and Zeitschrift für Assyriologie und Vorderasiatische Archäologie. Domänen studerades genom att analysera citeringar, materialet, språken, vart materialet publicerades, åldern på referenserna och författarna genom att visualisera mönster i figurer och tabeller. Forskningssamarbeten analyserades för att visa samarbeten mellan länder. Innehållet analyserades med en cociteringsanalys av referenser och en cowordanalys av titelord för att visualisera kognitiva strukturer inom domänen. Studien fann att cowordanalys gav en generell bild av olika kongnitiva strukturer men det fanns få tydliga strukturer. Cociteringsanalysen hittade fler tydliga strukturer men referenserna hade få citeringar och det är därmed möjligt att det inte representerar hela domänen. Det var effektivt att använda sig av tabeller och figurer för att visualisera olika aspekter inom domänen. Sammansfattningsvis, bibliometri var användart för att få nya kunskaper om domänen assyriologi.

The purpose of this Master’s thesis is to contribute to knowledge of what author-assigned keywords add to the indexing of Swedish dissertations in literature. This study had two research questions: 1) What types of keywords do the authors choose? 2) How do the author-assigned keywords compare to the cataloger-assigned subject headings from the controlled vocabulary Svenska Ämnesord (SAO) regarding types of terms, exhaustivity and specificity? Theoretical perspectives for this study come from Domain analysis which is a core paradigm within the research area Knowledge Organization (see e.g. Smiraglia 2015). Within Domain analysis the focus for indexing is the domain, and it is the needs of the domain that shall direct the indexing practice. The dataset of the study contained 34 dissertations in literature published in the Swedish university repository DiVA between 2012 and 2022, that had both author-assigned keywords in Swedish and were assigned sao-subject headings in the Swedish national catalogue Libris. In total 431 author keywords and 195 sao-subject headings were analysed using a modified version of thematic analysis as described by Braun & Clark (2006). The results reveal that the author-assigned keywords show more themes than the subject headings, and indicates higher exhaustivity and specificity. For example, one main theme for the keywords were discipline-related terms, that were often connected to theory/methodology for the dissertations, but the subject headings were lacking this as a main theme. Also names of philosophers and theorists formed a theme for the keywords, but the subject headings did not have this theme. Furthermore the findings show that the subject headings tended to be more general in character than the keywords. From the point of view of Domain analysis it is problematic if the indexing used in the university library databases does not meet the needs of the academic domains. Therefore it is argued in this thesis that either the author-assigned keywords should be better utilised within the national catalogue Libris, or that the policy for professional indexing should be adjusted to better meet the needs of the academic domains.

Metamaterials are typically described as materials with ’unusual’ wave propagation properties. Originally developed for electromagnetic waves, these materials have also spread into the field of acoustic wave guiding and cloaking, with the most relevant of these ’unusual’ properties, being the so called band-gap phenomenon. A band-gap signifies a frequency region where elastic waves cannot propagate through the material, which in principle, could be used to protect buildings from earthquakes. Based on this, two relevant concepts have been proposed in the field of seismic engineering, namely: metabarriers, and metamaterial-based foundations. This thesis deals with the development of the Metafoundation, a metamaterial-based foundation system for the seismic protection of fuel storage tanks against excessive base shear and pipeline rupture. Note that storage tanks have proven to be highly sensitive to earthquakes, can trigger sever economic and environmental consequences in case of failure and were therefore chosen as a superstructure for this study. Furthermore, when tanks are protected with traditional base isolation systems, the resulting horizontal displacements, during seismic action, may become excessively large and subsequently damage connected pipelines. A novel system to protect both, tank and pipeline, could significantly augment the overall safety of industrial plants. With the tank as the primary structure of interest in mind, the Metafoundation was conceived as a locally resonant metamaterial with a band gap encompassing the tanks critical eigenfrequency. The initial design comprised a continuous concrete matrix with embedded resonators and rubber inclusions, which was later reinvented to be a column based structure with steel springs for resonator suspension. After investigating the band-gap phenomenon, a parametric study of the system specifications showed that the horizontal stiffness of the overall foundation is crucial to its functionality, while the superstructure turned out to be non-negligible when tuning the resonators. Furthermore, storage tanks are commonly connected to pipeline system, which can be damaged by the interaction between tank and pipeline during seismic events. Due to the complex and nonlinear response of pipeline systems, the coupled tank-pipeline behaviour becomes increasingly difficult to represent through numerical models, which lead to the experimental study of a foundation-tank-pipeline setup. Under the aid of a hybrid simulation, only the pipeline needed to be represented via a physical substructure, while both tank and Metafoundation were modelled as numerical substrucutres and coupled to the pipeline. The results showed that the foundation can effectively reduce the stresses in the tank and, at the same time, limit the displacements imposed on the pipeline. Leading up on this, an optimization algorithm was developed in the frequency domain, under the consideration of superstructure and ground motion spectrum. The advantages of optimizing in the frequency domain were on the one hand the reduction of computational effort, and on the other hand the consideration of the stochastic nature of the earthquake. Based on this, two different performance indices, investigating interstory drifts and energy dissipation, revealed that neither superstructure nor ground motion can be disregarded when designing a metamaterial-based foundation. Moreover, a 4 m tall optimized foundation, designed to remain elastic when verified with a response spectrum analysis at a return period of 2475 years (according to NTC 2018), reduced the tanks base shear on average by 30%. These results indicated that the foundation was feasible and functional in terms of construction practices and dynamic response, yet unpractical from an economic point of view. In order to tackle the issue of reducing the uneconomic system size, a negative stiffness mechanism was invented and implemented into the foundation as a periodic structure. This mechanism, based on a local instability, amplified the metamaterial like properties and thereby enhanced the overall system performance. Note that due to the considered instability, the device exerted a nonlinear force-displacement relationship, which had the interesting effect of reducing the band-gap instead of increasing it. Furthermore, time history analyses demonstrated that with 50% of the maximum admissible negative stiffness, the foundation could be reduced to 1/3 of its original size, while maintaining its performance. Last but not least, a study on wire ropes as resonator suspension was conducted. Their nonlinear behaviour was approximated with the Bouc Wen model, subsequently linearized by means of stochastic techniques and finally optimized with the algorithm developed earlier. The conclusion was that wire ropes could be used as a more realistic suspension mechanism, while maintaining the high damping values required by the optimized foundation layouts. In sum, a metamaterial-based foundation system is developed and studied herein, with the main findings being: (i) a structure of this type is feasible under common construction practices; (ii) the shear stiffness of the system has a fundamental impact on its functionality; (iii) the superstructure cannot be neglected when studying metamaterial-based foundations; (iv) the complete coupled system can be tuned with an optimization algorithm based on calculations in the frequency domain; (v) an experimental study suggests that the system could be advantageous to connected pipelines; (vi) wire ropes may serve as resonator suspension; and (vii) a novel negative stiffness mechanism can effectively improve the system performance.