Σκοπός της εργασίας είναι να εξακριβώσει αν το φαινόμενο των μικρών εταιριών εμφανίζεται και εξηγείται από τις αποδόσεις σε χαρτοφυλάκια ελληνικών μετοχών, εταιριών εισηγμένων στο Χρηματιστήριο Αξιών Αθηνών (Χ.Α.Α.) την περίοδο 2005-2010. Δηλαδή να δούμε αν και σε ποιο βαθμό το μέγεθος της κεφαλαιοποίησης των επιχειρήσεων επηρεάζει τη διαμόρφωση των αποδόσεων των μετοχών τους. / The purpose of this study is to determine whether the phenomenon of small firms appears and explained by Greek yields portfolios of shares of companies listed on the Athens Stock Exchange (ASE) over the period 2005-2010. That is to see if and to what extent the size of the market capitalization of the company influence the formation of their stock returns.

The aim of this thesis is to design, implement and evaluate an experiment that verifies the influence the size effect on selected parameters of the surface integrity. For the experiment were used highly productive reaming head MT3 made by HAM-FINAL. Evaluation of the surface integrity was done in terms of the characteristics of the surface roughness, geometric tolerances and changes in microstructure. Furthermore, the influence of the depth of chips evaluated for changes in the feed force, cutting torque and changes in specific cutting energy. The theoretical part deals with the description of the size effect, characteristic reaming, surface integrity, preparation of material and identification of highly productive MT3 reaming head.

<p> New metal-rich Gd5T4 magnetocaloric phases (T - p-element) were designed, synthesized and characterized. These phases exhibit a close relationship between the valence electron count, size effect, crystal structure and physical properties. The targeted cleavage of the interslab T-T dimers was achieved in the Gd5Si4-xPx, Gd5Si4-xSbx and GdsSi4_xBix systems. While in the Gd5Si4-xPx system only a change in the valence electron count was employed for the desired structural transformations, in the Gd5Si4-xSbx and Gd5Si4-xBix systems both the valence electron count and size effect were used to break the interslab dimers. Incorporation of large Bi atoms into the Gd5Si4 phase resulted in the complete cleavage of the interslab T-T bonds and lead to novel slab stacking sequences accompanied by stacking faults. </p> <p> The Gd5Si4_xPx and Gd5Si4-xSbx phases undergo ferromagnetic transitions within a wide temperature range. Values of the corresponding magnetic entropy changes indicate the presence of a conventional magnetocaloric effect. This is likely due to the temperature stability of the structures with the broken dimers which hinders first-order coupled magnetostructural transitions. </p> <p> Metal-rich ferromagnetic phases of the RE5NixT3-x composition with RE = Gd, Dy, Lu, T = Sb, Bi were derived from the parent RE5T3 binaries. Incorporation of nickel stabilizes the orthorhombic Yb5Sb3-type structures at 800 °C. The Gd5Ni0.96Sb2.04, Gd5Ni0.71Bi2.29 and Dy5Ni0.66Bi2.34 phases show relatively low values of magnetocaloric effect. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

The idea underlying the present study was to apply twisting in order to introduce different levels of transverse pressure. The modified structure affected both the bonding level and the evolution of the damage in the yarn. In order to isolate this effect in a broader context, additional parameters were included in the experiment design, namely effects of loading rate, specimen length and filament diameter (directly linked to the fineness of the yarn). These factors have been studied in various contexts by several authors. Some related studies on involved factors will be briefly reviewed.

Nanoindentation has become a widely used technique to measure the mechanical properties of materials. Due to its capability to deform materials in micro- and nano-scale, nanoindentation has found more applications in characterizing the deformation behavior and determining the mechanical properties of thin films and coatings. This research deals with the characterization of samples received from Center for Advanced Microstructures and Devices (CAMD) and Integran Technologies Inc., Toronto, Canada and the objective of this investigation was to utilize the experimental data obtained from nanoindentation to determine the deformation behavior, mechanical properties of thin films on substrates and bulk materials, and the effect of geometrically different indenters (Berkovich, cubecorner, and conical). X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) analysis were performed on these materials to determine the crystal orientation, grain size of the material, and also to measure any substrate effects like pile-up or sin-in respectively. The results indicate that indentation size effect (ISE) strongly depends on shape of the indenter and less sensitive to penetration depth where as the hardness measurements depends on shape of indenter and depth of penetration. There is a negligible strain rate dependency of hardness at deeper depths and a significant increase in the hardness due to the decrease in grain size and results also indicate that there is no significant substrate effect on thin films for 10% and 20% of film thicknesses. Nanocrystalline material could not validate a dislocation based mechanisms deformation for indentation made by cubecorner and conical indenters in depths less than 1mm.

Martensitic phase transformation in NiTi shape memory alloys (SMA) occurs over a hierarchy of spatial scales, as evidenced from observed multiscale patterns of the martensitic phase fraction, which depend on the material microstructure and on the size of the SMA specimen. This paper presents a methodology for the multiscale tracking of the thermally induced martensitic phase transformation process in NiTi SMA. Fine scale stochastic phase field simulations are coupled to macroscale experimental measurements through the compound wavelet matrix method (CWM). A novel process for obtaining CWM fine scale wavelet coefficients is used that enhances the effectiveness of the method in transferring uncertainties from fine to coarse scales, and also ensures the preservation of spatial correlations in the phase fraction pattern. Size effects, well-documented in the literature, play an important role in designing the multiscale tracking methodology. Molecular dynamics (MD) simulations are employed to verify the phase field simulations in terms of different statistical measures and to demonstrate size effects at the nanometer scale. The effects of thermally induced martensite phase fraction uncertainties on the constitutive response of NiTi SMA is demonstrated.

This paper aims to examine if firms listed on Nasdaq Stockholm with dividend exposure yield higher risk-adjusted returns than firms without dividend exposure. Using a data set consisting of observations between 2000-2017 we test the difference in mean risk-adjusted return, measured by the Sharpe ratio, between securities with different levels of dividend exposure. We divide our sample into portfolios, categorized in the first stage independently of investment style, size and book-to-market ratio, and in the second stage on dividend exposure, that are regrouped annually. We measure the performance in terms of the geometric mean monthly returns, the risk as standard deviation of returns and the risk-adjusted performance measured with the Sharpe ratio. Following our empirical study, we find indications of a value effect in the Swedish capital market and draw upon three main conclusions. First, for all but one portfolio, the risk decreases with an increased degree of dividend exposure. Second, securities with high-dividend exposure tend to yield higher risk-adjusted returns relative to securities with no-dividend exposure. Third, the effect of dividend exposure on risk-adjusted performance appears to be most significant on mid firms and growth firms

Este estudo analisa a influência do porte empresarial no retorno das ações do mercado brasileiro, lidando com a sobreposição aparentemente existente entre porte da empresa e liquidez das ações e buscando elucidar qual variável é dominante na determinação de retornos acionários. Para tanto, utiliza-se uma análise de dados em painel como ferramenta econométrica para a obtenção de resultados significativos. Os modelos tradicionais de precificação de ativos, notadamente o CAPM, partem de algumas premissas que possuem pouca aderência à realidade dos mercados acionários. Há evidências de que, no Brasil, o CAPM tem sido ineficaz em explicar os retornos do mercado acionário. Por essa razão, algumas variáveis são comumente adicionadas ao modelo original, sendo que o porte empresarial se encontra no topo da lista. Contudo, a legitimidade do porte empresarial reduzido como fator de risco a ser remunerado ao acionista não é consensual em mercados mais maduros como o americano tampouco no mercado brasileiro. O estudo leva em conta um intervalo de tempo de 16 anos (de 1995 até 2011) e analisa a influência dessas variáveis no retorno das ações com diferentes defasagens de tempo entre as variáveis (de 1 a 5 anos). O trabalho conclui que há uma significativa influência do porte empresarial nos retornos das ações. A relação estatística é negativa, isto é, empresas de menor porte tendem a ter custo de capital próprio mais alto. Esse resultado está alinhado com a pesquisa internacional sobre o assunto. O modelo quantitativo sugere que a cada variação de uma unidade logarítmica no porte há uma variação de 4,03% no retorno esperado da ação. Em relação à liquidez não foi encontrada, de forma consistente, relação estatística de que essa variável afeta o retorno das ações quando controlada pelo porte empresarial no mercado brasileiro. / This study analyses the influence of company size in stock returns in Brazilian market, dealing with the apparent superposition between company size and stock liquidity and searching to elucidate which variable is dominant in determining stock returns. With that purpose, panel data analysis has been used as econometric technic, searching to obtain significant results. Traditional pricing models, mainly CAPM, are based on certain premises which have little in common with the stock markets. There is evidence that, in Brazil, CAPM has been unable to explain stock returns properly. For this reason, some variable are commonly added to the original model and the company size is at the top of the list. However, the legitimacy of the size effect as a risk factor to be paid off to the stockholder is neither consensual in more mature markets, as the American one, nor in the Brazilian market. The study takes into account a time span of 16 years (from 1995 to 2011) and analyses the influence of these variables in stock returns with different delays among variables (from 1 to 5 years). The work concludes that there is a significant size effect in stock returns. The statistical relation is negative, that is, smaller companies tend to have higher cost of equity. This result is aligned with the international research on the subject. The quantitative model suggest that for a logarithmic unit variation in company size there is a 4,03% additional cost of equity. Concerning liquidity, it has not been found, consistently, statistical relation that this variable affects stock returns when controlled by company in Brazilian market.

No trabalho estuda-se o crescimento de trincas em carga monotônica e cíclica nos casos de materiais quase-frágeis, introduzindo uma lei de dano cíclico. Revisam-se conceitos sobre modelos coesivos, leis de carga-descarga, leis de evolução de dano e efeito de escala. É seguido o modelo coesivo irreversível proposto por Wang e Siegmund (2006). Em particular se dá ênfase aos efeitos de escala não estatísticos. O modelo de zona coesiva irreversível apresenta uma formulação de dano e considera carregamento em fadiga. Quando o tamanho estrutural é reduzido (ou as trinca se extendem), a fratura por fadiga não mais ocorre por propagação de trinca, mas sim por uma decoesão uniforme. O objetivo desde trabalho é implementar este modelo e verificar sua potencialidade na captura de efeitos de escala, comparando com experimentos e dados disponíveis na literatura. / At present work is intended to study crack growth in cyclic and monotonic loading in the case of quasi-brittle materials, introducing a damage mechanism, is reviewed concepts of cohesive models, loading-unloading laws, damage evolution laws and effect of scale. The irreversible cohesive zone model proposed by Wang e Siegmund (2006) is followed. In particular emphasizes in the not statistical size effects. The irreversible cohesive zone model, presents a damage formulation and considers fatigue loading. It is demonstrated in this study that, when the structure size is reduced (or extend cracks), the fatigue fracture no longer occurs by crack propagation, then occurs by uniform decohesion . The objetive of this work is implementing this model and verify its capability to capture the scale effect compared with experiments and data available in literature.