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.

Understanding the mechanical properties and deformation characteristics of nanoscale metallic nanopillars and wires is a significant concern for designing reliable small devices that must resist loads in service. This thesis aims to extend understanding of the size dependent behaviour of nanopillars and wires in compression and tension by investigating their mechanical properties and deformation characteristics. Single crystal bcc pillars were fabricated by focussed ion beam (FIB) machining from Fe, Nb, V, Ta, Mo, W and Cr, as well as the ferrite (bcc) and austenite (fcc) components of a duplex stainless steel (DSS). These were tested in compression over a range of test temperatures from 193 K to 393 K using various types of nanomechanical devices. The effect of sample size (pillar diameter) on the strength was investigated and found to increase with decreasing pillar size. In bcc metals, the yield or flow stress, 􀀂􀀖, is inversely proportional with some power of the pillar diameter, d. In bcc metals tested, the power-law exponent, n, were found in the range of between -0.23 to -0.63, showing a less pronounced size effect than found for fcc pillars. The power-law exponent for bcc pillar deformation is also temperature dependent and was found to scale with the ratio of test temperature, Ttest to the critical temperature for screw dislocation mobility, Tc, of the bcc metal (T*= Ttest / Tc). It is notable that the size effect exponent weakens (approaches 0) as T* decreases. However, when the experiments are carried out at temperatures close to or just above Tc, the power-law exponents approaches the value reported in the literature for a range of fcc metals (-1 < n < -0.6). The variation in the power-law exponent observed for bcc metals can be explained by the change in mobility of thermally activated screw dislocations. Their mobility can be modelled by a threshold or lattice friction stress. If this friction stress is introduced into the empirical equation that relates the strength of fcc metal pillars to their diameter, a strong correlation between size effect exponent, the normalised test temperature (T*) and friction stress is obtained. It was found that the friction stress values (Fe, Nb and V) increase as Ttest decreases from 296 to 193 K. When the pillar diameter decreases, the friction stress would be more easily overcome due to the increase in surface-to-volume ratio. The contribution of lattice friction stress on the strength is higher at larger pillars than those for nanopillars. Thus, the divergence between best fit lines has become more apparent at micron-sized pillars, resulting in weaker size effects. Furthermore, the transition in deformation morphology from localized to wavy deformation was only found in Fe pillars, as the Ttest decreased from 296 to 193 K, further revealing that temperature has also strong influence on deformation behaviours of bcc pillars.

The Value investment and Growth investment are investment strategies of choosing stocks. These two methods are adopted by international financial investment institutions and mutual fund managers. The study is aim to learn when we classify value stock and growth stock by market-to-book ratio and price-earning ratio, if the investment return would be higher than TSEC weighted index. In addition, we seek for a better investment strategy to improve investment performance further. The study also looks into market abnormal effects , such as January effect, size effect¡Ketc, and also discuss about the variables of stocks holding period and debt ratio. The monthly and yearly investment return rates are used to calculate 1, 2, 3, 4, and 5 year accumulated abnormal stock return ratio and evaluate if these variables affect investment performance of value stock and growth stock. The results are as following: 1. When classification of market-to-book ratio are adopted, the investment return of value stock is higher than growth stock. 2. When classification of market-to-book ratio are adopted, the investment return of low debt ratio stock is higher than high debt ratio stock. However, when classification of price-earning ratio are adopted, it is not obvious. 3. When bull market is formed in Taiwan stock market whose index is still low, invest in value stock could get a good long term investment performance. 4. Regarding the evaluation of risk, the vibration of growth stock is more than value stock. The vibration of TSEC weighted index is the least. 5. The January effect exists in Taiwan stock market. However, the size effect is not obvious. 6. TSEC weighted index and the Dow Jones Industrial index affect the investment return of value stock and growth stock; the TSEC weighted index, value stock and growth stock are positively correlated. The Dow Jones Industrial Index, value stock and growth stock are negatively correlated.

This paper examines whether the phenomena of price drift around quarterly earnings re-leases exist among firms listed on the large cap. list at the Stockholm Stock Exchange for a time period ranging from the first quarter of 2003 to the second quarter of 2006. It fur-thermore examines the ability of the variables forecast error, relative to analyst’s estimates, and firms’ size to explain the variation in price drift among firms. A sample of some 30 firms were drawn in the first three quarters of each year between 2003 and 2005, for the year of 2006 only the fist two quarters were included in the study. For each quarter all firms were classified into three different portfolios on the basis of earnings deviations relative to mean analyst’s estimates (forecast error). The returns for each firm in all portfolios were investigated during 20 days post- and pre quarterly earnings release date, resulting in an event window totaling 41 days. In order to clear out effects from general market movements the Capital Asset Pricing Model, CAPM, was used in which betas were estimated for all firms each quarter. The findings from this study indicate that price drift, measured by cumulative abnormal re-turn, occur for firms with both negative forecast error as well as positive. For firms with positive error, statistically significant positive price drift was found for both the pre- and post period. As for the firms with earnings below analyst’s mean estimates, negative prean-nouncement drift was statistically supported. The ability of firms size and forecast error to explain the variation in price drift on a stock level was very weak, R2 measures of below 5% was reported. However, forecast error was a strongly significant independent variable in the context of the regressions run for both pre- and post-announcement drift. The firms below the lower market cap. quartile in the sample show, on average, lower pre-announcement drift than the firms belonging in the largest quartile. Concerning market efficiency among the large cap. firms the price drift found is an indica-tion of market inefficiency both it terms of the semi strong and the strong form. However, care should be taken before generalizing the results from this study but. Possible misspeci-fication of the equilibrium return model will skew the price drift measurement. Moreover, speculation is not explicitly controlled for in this test. Finally, this study is done within a li-mited time span; hence generalization over time is not possible

<p>This dissertation shows that the architecture of steam generators, steam turbines and heat exchangers for power plants can be predicted on the basis of the constructal law. According to constructal theory, the flow architecture emerges such that it provides progressively greater access to its currents. Each chapter shows how constructal theory guides the generation of designs in pursuit of higher performance. Chapter two shows the tube diameters, the number of riser tubes, the water circulation rate and the rate of steam production are determined by maximizing the heat transfer rate from hot gases to riser tubes and minimizing the global flow resistance under the fixed volume constraint. Chapter three shows how the optimal spacing between adjacent tubes, the number of tubes for the downcomer and the riser and the location of the flow reversal for the continuous steam generator are determined by the intersection of asymptotes method, and by minimizing the flow resistance under the fixed volume constraints. Chapter four shows that the mass inventory for steam turbines can be distributed between high pressure and low pressure turbines such that the global performance of the power plant is maximal under the total mass constraint. Chapter five presents the more general configuration of a two-stream heat exchanger with forced convection of the hot side and natural circulation on the cold side. Chapter six demonstrates that segmenting a tube with condensation on the outer surface leads to a smaller thermal resistance, and generates design criteria for the performance of multi-tube designs.</p> / Dissertation