Above ground steel storage tanks are used worldwide for the storage of various liquids. EN 14015:2005, which has traditionally been used to design the tanks, does not necessarily fulfil the requirements of the Swedish Building Code. This has been underlined by hand calculation models in EN 1993-1-6:2007, EN 1993-4-2:2007 and numerical analysis using Finite Element Method (FEM). Therefore, this thesis investigates the differences between these design models and, preliminarily, the use of high-strength steel in tank shells. A 10600 m3 cylindrical steel tank of diameter 26 m and height of 21 m located in Gothenburg, Sweden is studied. The study is limited to the assessment of the stress in the shell courses due to the hydrostatic pressure from the fluid action of a filled tank, and the buckling behaviour of the shell courses of an empty tank subjected to self-weight, snow and wind loads. Particularly, models of the tank shell with a yield strength of 355 MPa are investigated in detail, while the results of the 700 MPa model are considered as preliminary study, since the material is currently not used for tank shells. An analysis of the fluid action on the tank shell courses in each of the three hand calculation models, showed that the EN 14015 model utilizes thicker courses than both Eurocodes. One benefit of the Eurocode models is that they do not limit the thickness of the shell courses, but it is still necessary to have thicker courses in the upper part of the tank in order to achieve sufficient resistance against buckling. EN 14015:2005, on the other hand, limits the minimum thickness to 6 mm for the investigated tank. Furthermore, only EN 1993-1-6 is applicable to the models with a yield strength of 700 MPa as per EN 1993-1-12 and this resulted in a uniform shell thickness of 6 mm. However, an increase in yield strength has no buckling benefits whatsoever.  Buckling is the most critical aspect as observed in this study. EN 14015 has no specific buckling calculations but uses the approach of determining the number of stiffening rings which are deemed adequate against buckling. In this study, 3 secondary stiffening rings were found to be adequate. In comparison, the results of EN 1993-4-2 are very conservative and lead to a very high and uneconomical number of stiffening rings, ranging from 30 to 52 stiffening rings depending on the reliability class. EN 1993-1-6 resulted in 6-17 stiffening rings, for reliability classes 1-3 and fabrication classes A-C. Therefore, the so-called analytical models in the Eurocodes result in a much denser spacing of stiffening rings than 14015:2005.  The buckling stresses due to the design loads were found to be lower than the yield strength of the tank shells for both hand calculation and FEM models. This means that the tank shells failed in buckling before the yield strength of the material was reached. Based on the parametric study of the EN 1993-1-6 (355 MPa) model regarding reliability class 1 and fabrication class A using FEM, the spacing of the stiffening rings can be increased up to 60 % (from 3825 mm to 6120 mm) with the variable loads also increased simultaneously up to 3.8 times before the shell buckles. Therefore, the design of future tanks using numerical analysis guarantee’s more reliability than all the aforementioned standards.  The design for buckling according to EN 14015 is only valid for a design snow load and under-pressure ≤ 1.2 KN/m2. However, according to the standard itis possible to agree to use it for larger actions or use another design model for buckling.

This dissertation collects three essays which deal with financial development in emerging markets. Owing to the appliance of different econometric methods on several data sets, insights in the behavior of and the impacts from financial markets are generated. Usually, the financial markets in emerging countries are characterized by the presence of credit constraints. In the first chapter it is shown that the financial development in 19th century Germany generally affected the economy in a positive way. Additionally, when different economic sectors are under investigation, it is revealed that the reaction due to financial development is not homogeneously across the sectors. A structural vector autoregression (VAR) framework is applied to a new annual data set from 1870 to 1912 that was initially compiled by Walther Hoffmann (1965). With respect to the literature, the most important difference of this analysis is the focus on different sectors in the economy and the interpretation of the results in the context of a two-sector growth model. It is revealed that all sectors were affected significantly by shocks from the banking system. Interestingly, this link is the strongest in sectors with small or non-tradable-goods-producing firms, such as construction, services, transportation and agriculture. In this regard, the growth patterns in 19th century Germany are reminiscent to those in today's emerging markets. The second chapter deals with the integration of the stock markets of mainland China with those of the United States and Hong Kong. Market integration and the resulting welfare gains as risk sharing, increasing investment and growth benefits has become a central topic in international finance research. This chapter investigates stock market integration after stock market liberalization which is assessed by spillover effects from Hong Kong and the United States to Chinese stock market indices. Dividing the sample in pre- and post-liberalization phases, causality in variance procedure is applied using four mainland China stock market indices, two indices of the stock exchange in Hong Kong and the Dow Jones Industrials index in the main part. Evidence of global and regional integration is found, but no evidence for increasing integration after the partial opening of the Chinese stock markets, neither with Hong Kong nor with the United States. Based on the idea presented in the first chapter, the third chapter examines one of today's emerging markets. As China is experiencing remarkable economic growth in the recent decades, it is analyzed if and to what extent the ongoing deregulations in the financial system contribute to this development. Structural VARs for gross domestic product as well as for sectoral output data in conjunction with two different bank lending variables are applied. It is indicated that China is positive affected by financial development and that all sectors benefit from domestic bank lending enlargements but to different degrees. Especially in the sectors where mainly state-owned enterprises are represented - such as construction, trade and transportation - shocks in bank lending have a strong positive influence while sectors where private enterprises are prevalent, seem to be more credit constrained.

The conduct of effective economic policy faces a multiplicity of macroeconomic challenges, which requires a wide scope of theoretical and empirical analyses. With a focus on the European Union, this doctoral dissertation consists of two parts which make empirical and methodological contributions to the literature on forecasting real economic activity and on the analysis of business cycles in a boom-bust framework in the light of the EMU enlargement. In the first part, we tackle the problem of publication lags and analyse the role of the information flow in computing short-term forecasts up to one quarter ahead for the euro area GDP and its main components. A huge dataset of monthly indicators is used to estimate simple bridge equations. The individual forecasts are then pooled, using different weighting schemes. To take into consideration the release calendar of each indicator, six forecasts are compiled successively during the quarter. We find that the sequencing of information determines the weight allocated to each block of indicators, especially when the first month of hard data becomes available. This conclusion extends the findings of the recent literature. Moreover, when combining forecasts, two weighting schemes are found to outperform the equal weighting scheme in almost all cases. In the second part, we focus on the potential accession of the new EU Member States in Central and Eastern Europe to the euro area. In contrast to the discussion of Optimum Currency Areas, we follow a non-standard approach for the discussion on abandonment of national currencies the boom-bust theory. We analyse whether evidence for boom-bust cycles is given and draw conclusions whether these countries should join the EMU in the near future. Using a broad range of data sets and empirical methods we document credit market imperfections, comprising asymmetric financing opportunities across sectors, excess foreign currency liabilities and contract enforceability problems both at macro and micro level. Furthermore, we depart from the standard analysis of comovements of business cycles among countries and rather consider long-run and short-run comovements across sectors. While the results differ across countries, we find evidence for credit market imperfections in Central and Eastern Europe and different sectoral reactions to shocks. This gives favour for the assessment of the potential euro accession using this supplementary, non-standard approach.

The presented paper deals with a theoretical analysis of the ultimate limit state. The results of experimental research carried out at the Institute of Metal and Timber Structures headed by Assoc. Prof. Karmazinová and Professor Melcher were applied. The geometrically and materially nonlinear solution based on the Timošenko’s solution is verified by the FEM model in the computer programme system ANSYS. The random influence of initial imperfections is taken into consideration. The FEM model also includes the influence of residual stress. In the parametric study, the influence of residual stress on the cross-section plastification is researched into, its influence on the load carrying capacity limit is, together with the influence of other imperfections, the subject of the stochastic analysis, applying the Latin Hypercube Sampling (LHS). Further on, the study proves a direct effect of the concrete part of the cross-section (combination of materials steel-concrete) on the decrease of load carrying capacity limit of the beam caused by influence of the residual stress of steel. With regard to the importance of time dependent phenomena of the concrete creep for the load carrying capacity, the studies given in the Ph.D. thesis are oriented in this respect. The parametric studies of the influence of the concrete creep having applied the Standard Eurocode 2 provide both a comparison of load carrying capacity limits when using common and high-strength concrete types, and also the variability of load carrying capacities. It follows from the comparison of the statistical analysis outputs according to the design reliability conditions of the Standard EN1990 and of the approach of Eurocode 4 that the Eurocode 4 can be recommended for dimensioning of this member type. According to the studies which we carried out, the design in compliance with Eurocode 4 can be evaluated as the reliable one. A larger set of experimental data is necessary to determine the economy.

There are several reasons for using non-Cartesian k-space sampling methods in Magnetic Resonance Imaging (MRI). Such a method is radial sampling, which includes the advantage of continuous coverage of the k-space center which results in higher robustness to motion. On the other hand, radial imaging does have some limitations that must be considered. The method is more sensitive to gradient imperfections, such as eddy currents and gradient delays, resulting in inconsistencies between the nominal and actual gradient waveforms. This leads to distortions in the sampling trajectory, also called trajectory errors, yielding reconstructed images with artifacts caused by the gradient imperfections. The aim of this project was therefore to implement a method that takes these errors into account and perform a correction of the trajectory errors to yield images with reduced artifacts. Various methods have been proposed for correction of the gradient errors, some more effective than others. The method implemented in this project was based on the gradient impulse response function (GIRF) which characterizes the gradient system responses. When GIRF was acquired, the actual gradient waveforms played-out during the imaging measurement could be predicted by first modeling the nominal gradient waveforms and then performing a convolution with the corresponding GIRF for each gradient axis. The imaging experiments involved measurements on two different resolution phantoms and in-vivo measurements to note possible differences in correction performance. The used pulse sequences for imaging were FLASH and bSSFP. The results showed that the applied method using GIRF did reduce the artifacts caused by gradient imperfections in the reconstructed images taken with the FLASH sequence. On the other hand, the results for the bSSFP sequence were not as successful due to incomplete modeling of the gradient waveforms. The conclusion to be drawn is that the GIRF-correction does adequately compensate for the trajectory errors when using a radial sampling trajectory for the FLASH sequence and hence yield images with almost eliminated artifacts. A suggestion for future work would be to further investigate the bSSFP sequence modeling to obtain better bSSFP-images. / Det finns flera anledningar till att använda icke-Kartesiska k-space samplingsmetoder i magnetisk resonanstomografi. En sådan metod är radiell sampling, som har fördelen att kontinuerligt samla in mätdata från mittpunkten av k-space, vilket resulterar i lägre rörelsekänslighet under bildtagningstillfället. Radiell sampling har dock begränsningar som måste tas i beaktande, som gradient imperfektioner och gradientfördröjningar. Dessa leder till förvrängningar i samplingspositioneringen i k-space, även känt som trajektoriefel, vilket ger upphov till artefakter vid bildrekonstruktion. Syftet med projektet är att korrigera för dessa trajektoriefel så att den rekonstruerade bilden innehåller färre artefakter. Olika metoder har föreslagits för korrektion av gradientfel. Metoden som användes i detta projekt baseras på gradient impulsresponsfunktionen (GIRF), som karaktäriserar gradient systemet. För att estimera de verkliga samplingspositionerna i k-space beräknades de förvrängda gradientvågformerna efter varje mätning. Detta gjordes genom att först modellera de nominella gradientvågformerna och därefter utföra en faltning med GIRF. De utförda experimenten under projektets gång bestod av bildtagning av två fantomer och ett antal in-vivo mätningar för att identifiera eventuella skillnader i de rekonstruerade bilderna. Pulssekvenserna som användes under projektet var FLASH och bSSFP. Resultaten visade att GIRF-korrektionen reducerade artefakter orsakade av gradient imperfektioner i de rekonstruerade bilderna tagna med FLASH-sekvensen. Erhållna resultat med bSSFP-sekvensen var å andra sidan inte lika lyckade på grund av inkomplett modellering av gradientvågformerna. Slutsatsen som kan dras är att GIRF-korrektionen kompenserar för trajektoriefel i radiell sampling för FLASH-sekvensen och ger rekonstruerade bilder där artefakterna nästan eliminerats. Ett förslag för framtida arbeten är att vidare undersöka modelleringen av bSSFP-sekvensen för att erhålla bättre bilder.

For the stability assessment of members and structures according to EN 1993-1-1 the equivalent member method, the geometrical nonlinear calculation with equivalent geometrical imperfections or the GMNIA analysis with geometrical imperfections and residual stresses can be used alternatively. The second possibility requires a corresponding model for the cross-section resistance. For the verification of lateral torsional buckling, bow imperfections e0 out of plane are defined, which lead in combination with the given loading in plane and the geometrical non-linear analysis to bending Mz and torsion of the members. The amplitudes of the imperfections are highly dependent on the nature of the approach (e.g., scaling of the buckling shape, assumption of bow imperfections) and the resistance model for the members. Within the framework of the scientific work supervised by the TU Dresden and the TU Darmstadt [1], extensive parameter studies were carried out to calibrate imperfections for lateral torsional buckling based on the GMNIA. After determining the nature of imperfections and the design models for section resistance, this paper presents results of these parameter studies and shows the calibration of imperfections for a standardisation proposal based on EN1993-1-1. The evaluation of the data in combination with the necessary simplifications for the design practice leads to appropriate definitions of imperfection values e0,LT and the necessary differentiations.

For the stability assessment of members and structures according to EN 1993-1-1, the equivalent member method, the geometrical non-linear calculation with equivalent geometrical imperfections or the GMNIA analysis with geometrical imperfections and residual stresses can be used alternatively. The second possibility requires a corresponding model for the cross-section resistance. For the verification of lateral torsional buckling, bow imperfections e0 out-of-plane are defined, which lead in combination with the given loading in-plane and the geometrical non-linear analysis to bending moments Mz and torsion of the members. The amplitudes of the imperfections are highly dependent on the nature of the approach (e.g., scaling of the buckling shape, assumption of bow imperfections) and the verification method for the members. Within the framework of the scientific work supervised by the TU Dresden and TU Darmstadt, extensive parametric studies were conducted to calibrate imperfections for lateral torsional buckling based on the GMNIA. After determining the nature of imperfections and the design models for section resistance, this article presents results of these parametric studies and shows the calibration of imperfections for a standardisation proposal based on EN1993-1-1. The evaluation of the data in combination with the necessary simplifications for the design practice leads to appropriate definitions of imperfection values e0,LT and the necessary differentiations.

Adaptive antenna systems (AAS's) are traditionally of interest only in radar and sonar applications. However, since the onset of the explosive growth in demand for wireless communications during the 1990's, researchers are giving increasing attention to the use of AAS technology to overcome practical challenges in providing the service. The main benefit of the technology lies in its ability to exploit the spatial domain, on top of the temporal and frequency domains, to improve on transceiver performance. This thesis presents a unified study on two classes of preprocessing techniques for uniform circular arrays (UCA's). UCA's are of interest because of their natural ability to provide a full azimuth (i.e. 360') coverage found in typical scenarios for sensor array applications, such as radar, sonar and wireless communications. The two classes of preprocessing techniques studied are the Davies transformation and the interpolated array transformations. These techniques yield a mathematically more convenient form - the Vandermonde form - for the array steering vector via a linear transformation. The Vandermonde form is useful for different applications such as direction-of-arrival (DOA) estimation and optimum or minimum variance distortionless response (MVDR) beamforming in correlated signal environment and beampattem synthesis. A novel interpolated array transformation is proposed to overcome limitations in the existing interpolated array transformations. A disadvantage of the two classes of preprocessing techniques for UCA's with omnidirectional elements is the lack of robustness in the transformed array steering vector to array imperfections under certain conditions. In order to mitigate the robustness problem, optimisation problems are formulated to modify the transformation matrices. / Suitable optimisation techniques are then applied to obtain more robust transformations. The improved transformations are shown to improve robustness but at the cost of larger transformation errors. The benefits of the robustification procedure are most apparent in DOA estimation. In addition to the algorithm level studies, the thesis also investigates the use of AAS technology with respect to two different third generation (3G) mobile communications systems: Enhanced Data rates for Global Evolution (EDGE) and Wideband Code Division Multiple Access (WCDMA). EDGE, or more generally GSM/EDGE Radio Access Network (GERAN), is the evolution of the widely successful GSM system to provide 3G mobile services in the existing radio spectrum. It builds on the TDMA technology of GSM and relies on improved coding and higher order modulation schemes to provide packet-based services at high data rates. WCDMA, on the other hand, is based on CDMA technology and is specially designed and streamlined for 3G mobile services. For WCDMA, a single-user approach to DOA estimation which utilises the user spreading code and the pulse-shaped chip waveform is proposed. It is shown that the proposed approach produces promising performance improvements. The studies with EDGE are concerned with the evaluation of a simple AAS at the system and link levels. / Results from, the system and link level simulations are presented to demonstrate the effectiveness of AAS technology in the new mobile communications system. Finally, it is noted that the WCDMA and EDGE link level simulations employ the newly developed COST259 directional channel model, which is capable of producing accurate channel realisations of macrocell environments for the evaluation of AAS's.

Dans le cadre des systèmes de communications radio mobiles de la 4ème génération, on s'est intéressé aux systèmes combinant les techniques d'étalement par les codes et de transmission à porteuses multiples.<br />La thèse consiste à étudier en premier lieu les performances des différents types de combinaisons de l'OFDM et du CDMA, appelées sous le nom générique « OFDM-CDMA », dans un environnement parfaitement synchronisé dans une liaison descendante avec les mêmes conditions de transmission : charge du système, constellation, rendement du codage.<br />Une fois la comparaison des différents systèmes établie dans un contexte parfaitement synchronisé, on traitera le problème des imperfections de transmission : erreurs des synchronisation, imperfections Radio Fréquences (RF), estimation du canal, effet Doppler.<br />Les différents types d'erreurs de synchronisation étudiés dans le manuscrit sont la synchronisation de la fenêtre temporelle, la synchronisation des fréquences porteuse, et d'échantillonnage.<br />Les imperfections RF étudiées consistent en le bruit de phase et la gigue d'horloge.<br />Les sensibilités de l'OFDM-CDMA à ces erreurs sont évaluées en fonction du Rapport Signal à Interférence plus Bruit (RSIB) en sortie du détecteur en tenant compte de l'orthogonalité entre les codes d'étalement.<br />Finalement, on s'intéresse à évaluer les performances de ces systèmes en terme du Taux d'Erreur Binaire (TEB) en sortie du décodeur et à faire le lien entre le RSIB en sortie du détecteur et le TEB en sortie du décodeur.<br />En conclusion de ce travail, on peut tirer des limites tolérées sur les imperfections de transmission de ces systèmes ainsi qu'une comparaison entre leurs performances.

Submitted by RODRIGO DE HOLANDA SCHMIDT (rodrigohs1979@gmail.com) on 2018-01-17T18:29:25Z No. of bitstreams: 1 PROJETO Posdefesa Versão FINAL.pdf: 1906537 bytes, checksum: 3b5e67507ea1b0d7bda550480252ae26 (MD5) / Approved for entry into archive by Janete de Oliveira Feitosa (janete.feitosa@fgv.br) on 2018-01-18T18:30:52Z (GMT) No. of bitstreams: 1 PROJETO Posdefesa Versão FINAL.pdf: 1906537 bytes, checksum: 3b5e67507ea1b0d7bda550480252ae26 (MD5) / Made available in DSpace on 2018-01-30T12:08:34Z (GMT). No. of bitstreams: 1 PROJETO Posdefesa Versão FINAL.pdf: 1906537 bytes, checksum: 3b5e67507ea1b0d7bda550480252ae26 (MD5) Previous issue date: 2017-11-30 / Purpose – The aim of this study was to comprehend the main determinant factors for vertical integration in the pulp and paper sector in Brazil, from a perspective of pulp manufacturers. Design/methodology – The research adopted a qualitative approach, through a multiple case study with three of the main companies in the pulp and paper sector in Brazil. The data collection was done through semi-structured interviews of executives of the selected companies. Findings – The main competitive advantage arises from the vertical integration backward, of the pulp mill towards the forestry. The main factors for this are the exercise of the market power of oligopoly by the pulp companies, assurance of supply of their main input, the wood, asset specificity of site, shortening the distance between the forest and the pulp mill, and mitigation of uncertainty. There is tapered integration of pulp mill and forestry, mainly due the use of advantages of site specificity of forest producers near the mill, the need to mitigate social risks and to develop a mature market for the commercialization of wood in the country. Research limitations – The main limitation of this work is the fact that the pulp sector is a concentrated oligopoly, with few companies, which restricts the diversity and number of respondents. Practical implications – The results can be applied to organizations in the pulp and paper sector, as well as to other capital-intensive industries with high dependence on a particular raw material. Originality– To our knowledge, this is the first study about vertical integration in the pulp and paper sector in Brazil. / Objetivo – Este estudo pretende compreender os principais determinantes para a integração vertical no setor de papel e celulose no Brasil, a partir de uma perspectiva das fabricantes de celulose. Metodologia – A pesquisa seguiu uma abordagem qualitativa, por meio de estudo de casos múltiplos com três das principais empresas do setor de papel e celulose do Brasil. A coleta de dados foi feita por meio de entrevistas semiestruturadas de executivos das empresas selecionadas. Resultados – A principal vantagem competitiva verificada se deu na integração vertical realizada à montante pela fábrica de celulose, em direção à produção florestal. Os principais fatores para isso foram o exercício do poder de mercado de oligopólio pelas empresas de celulose, a garantia de fornecimento do seu insumo principal, a madeira, a especificidade de local dos ativos, dada pela proximidade necessária entre a floresta e a unidade de celulose, e a mitigação da incerteza. A integração vertical entre fábrica de celulose e produção florestal é realizada de forma parcial, principalmente devido ao aproveitamento de vantagens de localização de produtores florestais próximos à fabrica, à necessidade de mitigar riscos sociais e de desenvolver um mercado maduro de comercialização de madeira no país. Limitações – A principal limitação deste trabalho é o fato do setor de celulose ser um oligopólio concentrado, com poucas empresas, o que restringe a diversidade e o número de entrevistados. Aplicabilidade do trabalho – Os resultados obtidos podem ser aplicados às organizações do setor de papel e celulose, bem como a outras indústrias de capital intensivo e com alta dependência de uma matéria-prima em especial. Originalidade – Pelo que conhecemos, é o primeiro trabalho sobre integração vertical no setor de papel e celulose no Brasil.